Fullerscopes Telescope Mountings

MV80 V Philips webcam.

2012-02-10T08:01:00.000-08:00

Feb 10th 2012

I had bought a tiny MV80 video camera as a supermarket cheap offer. Twice the price after buying a micro memory card. 8GB Class 6 Silicon Power.

Used as a webcam the MV80 exceeds the image quality of my Philips SPC230NC webcam. This is quite noticeable on full screen on my 23" Philips LCD monitor. Both claim a 640x 480 resolution. I used the supplied MV80 webcam (Amcap) software for both cameras. I have no idea if this favoured the mV80. The Philips software seemed not to improve matters over the Amcap.

I have never tried webcam astro imaging due to a lack of a laptop computer. So I am limited to the length of a long USB cable.

The MV80 Spycam beside a USB stick. It has a tiny lens which better suits digiscoping compared with many digital cameras. Fitting it to the digiscoping adaptor should not be difficult.

Two planets and the Moon are south at the moment so I might just be able to capture something through an upstairs window. The recent winter weather has been harsh. With lying snow, winds and very low temperatures at night. Down to at least -2F, -19C. Foolishly low for observing out on the open lawn.

Click on any image for an enlargement.

26.1.12

2012-01-26T10:30:00.000-08:00

Another attempt with the Digiscoping adapter. This time on the low, winter sun. The temperature was just below freezing with a 30mph gale blowing! Thanks to the frost the ground was hard enough to bear the weight of the castors of my massive pier which supports the MkIV. I dragged it around the outside of the obscuring house to reach the last shaft of sunlight between the neighbour's trees. It is always a problem to have the house on the southern border of one's plot!

I fitted the 6" refractor with the Baader solar filter in place. Then put the digiscoping adaptor with my old Sony P71 camera onto a 26mm eyepiece. Though I had previously focused visually the results seemed to be out of focus. With no sign of the clearly visible sun spots at the centre of the sun's disk. The sun sank below the trees all too rapidly in the very difficult conditions so I packed everything away again.

The moon stood almost directly south when I glanced out later. With the wind still blowing a gale and the temperature at -2C I shall wait until a better moment!

Digiscoping adapter review.

2012-01-13T10:46:00.000-08:00

The digiscoping adaptor had arrived a week earlier but I had no chance to use it until tonight. I carried out my 6" F:8 Celestron refractor and put it on the MkIV mounting. The drive box was attached and connected to the mains. After a quick peek at Venus and a quick but poor "snap" I concentrated on Jupiter. Which was very bright and quite high overhead to the South at about 50 degrees altitude. It traversed above the roof of my house as the evening wore on.

Having centred Jupiter I clamped the drives and started playing with the digi-scoping adaptor. I used a 2" star diagonal throughout. The MkIV had to be dragged across the lawn to be able to see Venus. So it wasn't more than roughly aligned on the Pole. It was also well out of level. This meant that the mounting did not track Jupiter as well as usual. Small adjustments had to be made to recentre it at regular intervals.

While it seems like a logical design and has adjustments in all planes the adapter is not at all easy to align properly. The camera lens and eyepiece should be on the same axis and as close to each other as possible when extended. The camera should also be firmly clamped and square to the eyepiece. Not an easy task in practice.

Short eyepieces have no length to mount the rather broad eyepiece clamp. The clamp is padded to avoid damage to eyepieces. It should be admitted that the adapter is primarily designed for use with spotting scopes. These tend to have longer eyepieces compared with astro telescopes. Using a Barlow lens allowed longer eyepieces to be used but with higher powers. So there was no real disadvantage.

The camera must be mounted on the rather slippery, perforated plastic support plate. While simultaneously placing the lens at the correct distance from the eyepiece. A sheet of rubber glued to the top surface of the camera support plate would probably help here. Though it was not difficult to lock the camera firmly once it was finally aligned.

There is a danger that the leverage provided by the adapter, once clamped, will unscrew an eyepiece barrel. This occurred a number of times.

The adapter slide adjustments are rather sloppy too. With the vertical adjustment particularly difficult. Because the adjustment wheel is blocked by the adapter casting foot. Had the wheel been larger this would not have been such a problem. I shall see if I can't modify this aspect of the adapter by fitting a larger wheel. I'm not sure it can be dismantled.

A locking knob at the back of the adjustable slides is supposed to clamp the lateral and vertical adjustments once the camera is centred. I found that this tended to put out the adjustments already made.

In the end, I used a white wall lit by an outside light to centre the out of focus, bare eyepiece circle in the camera screen. Then locked the adapter slides with the knob. Further adjustments were then made and the adapter relocked. The adapter was then carried complete with camera and 20mm eyepiece to the telescope.

However, once the adapter is in place one can no longer look through the eyepiece! If I took off the adaptor assembly complete with camera and eyepiece I could not guarantee something hadn't moved in the meantime. Or the planet had drifted out of the field of view! After some fiddling, I found it best to remove the eyepiece complete with camera and adapter. Another eyepiece was then substituted in the focuser until the planet was properly centred. Had I set up the mounting properly I could have saved some time.

I spent quite some time trying to find Jupiter on the camera screen. Eventually, I lifted off the adaptor assembly (as above) and then centred Jupiter in a wider angle eyepiece. Back on with the adapter and clamped eyepiece and still no sign of the planet on the screen! Eventually, after a lot of nudging the telescope I found the bright dot and could keep it centred. I had previously adjusted the finder telescope to ensure it was on axis with the main telescope.

The problem was seeing whether Jupiter was on the unlit cross-hairs. I am not a great fan of the sprung mounting on the 9 x 50mm finder. Though optically it seems very good. I have several small astro refractors of 60mm and 70mm aperture which could be fitted into home made finder rings with a good stand-off distance. Not to mention further forward of the eyepiece than the supplied finder. Having the finder and telescope eyepieces in the same plane is often a real nuisance when using a star diagonal. They always seem to get in each others way!

First I tried the Panasonic Lumix TZ7 camera. Results were not very good at all. I tried various eyepieces and degrees of camera zoom. Back indoors with the images copied to Picasa 3 I was rather surprised to see how many stars I had captured! The planet itself was an overexposed blob with 3 moons visible! The camera is capable of Ev adjustment but I'll try that another time.

Then I tried my old Sony P71 camera. I had more luck with this but the results are still hardly worth sharing. The resolution is much lower and cropping to increase image scale only exaggerates the graininess. The Jovian moons were soon lost with the slightest adjustment of contrast or gamma.

These are two of the best images from the P71 but are still barely recognisable:

The adapter obviously needs some practice to make the most of it. The Moon would offer a far better target for such practice. But it doesn't rise until much later tonight. Being a morning object at present.

I'm really not too disappointed with the digi-scoping adapter. It held the camera still and on axis far better than my usual hand-held efforts ever could. I would often take 50 shots hand-held and discard most of them due to off-centre flare. Once the planet was centred in the camera screen on thr adaptor I could easily adjust zoom and focus. The MkIV then kept everything nicely still while I snapped away. No need for a camera, cable release with the massive MkIV on its very heavy pier.

I think I'll go back out now and enjoy some casual, visual observing instead. Orion was quite low in the South East but well worth a look at the nebula with various powers. It seemed very clear with wings and indentations. The Trapezium was easily seen. Thought the stars were not particularly small or round. Some adjustment to the telescope alignment may be due after stripping it down to clean the back of the objective. I tried my Cheshire alignment eyepiece but there wasn't enough light to see anything useful.

I stared at Jupiter too with every eyepiece I had in the box but couldn't see much more than two broad, rather smudgy belts. There was no real detail at any power. My feet were getting rather cold by 10pm so I packed everything away.

Click on any image for an enlargement.

Digiscoping adaptor

2011-12-21T05:10:00.000-08:00

I have bought a digiscoping adapter from eBay. Until I receive it I shall use the vendor's excellent pictures.

He is being remarkably communicative with email updates of order acceptance and despatch. It is supposed to be coming from Germany so there is hope for an early delivery. Possibly even before Christmas? I doubt it.

It was long overdue that I stopped my hand-held snapping away at astro objects through the eyepiece. I did use an eyepiece clamp and camera plate for the Venus transit. But, it was so incredibly awkward to use with the telescope pointing high up that I never used it again!

I couldn't see the camera focusing screen hidden underneath the camera body without crawling on my knees. Or lying on the wet grass on my back! Even if I did, I couldn't focus my own eyes with my glasses having the reading section at the bottom of the lenses. (as is perfectly normal of course)

I wanted to use my star diagonal but my home made clamp was for my 2" draw-tube. My star diagonal (at that time) only accepted (normal) 1.25" eyepieces! I now have a 2" star diagonal but it is massively oversized for my 2" clamp. Grrr. So I really needed a universal camera platform which clamped onto the outside of my 1.25" eyepieces. One which could be (hopefully) set and forgotten.

I went to the city (Odense) and dashed about between milling Christmas shoppers. But I failed to find an adaptor in any of the local camera or hunting shops. (Hunting shops stock spotting telescopes)

So I tried eBay. I missed a secondhand one. This went higher than I wanted to pay for a used one including international postage.

So I paid a "Buy it Now" price for half what it would cost me from an online Danish vendor. (Including their ridiculous postal charges!)

The eBay vendor claimed their stock is in Germany. Right next door to Denmark. Their international postal charges are still lower than within Denmark. I will name the vendor on receipt if their service is good enough.

I'll leave this note until it arrives. Then I can take my own pictures with my camera fitted to an eyepiece. Hopefully the device will improve my astro snaps. I shall write a proper review when I can examine the adapter for myself. Hopefully with some decent lunar images taken with its help.

Click on any image for an enlargement.

Dec 10th 2011 partial lunar eclipse.

2011-12-10T08:14:00.001-08:00

As usual (for me) the partial eclipse was very low and blocked by clouds. The eclipse was already under way as the moon rose. Though it was completely invisible behind the clouds. When it did become visible I took a few snaps with my Panasonic TZ7. The camera was resting on a garden tool handle.

Full zoom with a variety of settings. Night landscape, Normal picture and various AF (auto focussing) settings. Had it been more worthwhile I could have got out my video tripod or even a telescope at low power. As can be seen here the Moon was almost behind the garden hedge. The clouds only added to the drama.

These are only for a record of the event. I have cropped some of them to bring out the moonlit clouds.

Click on any image for an enlargement.

December 2nd 2011

2011-12-02T11:02:00.001-08:00

Another clear evening with occasional plates of cloud passing over. Half moon to the south. Jupiter rising steeply in the east.

6" F:8 Celestron CR150HD refractor on Fullerscopes MkIV mounting. Stopped down to 4" F:12. Afocal image using 20mm no-name Plossl. Sony P71 camera hand-held to eyepiece. No drives running. Cropped, Contrast and Gamma adjusted in PhotoFiltre to bring out detail away from the terminator. 37F. Heavy dew. Thermal effects clearly visible. Moon just above house roof and chimney.

I fitted the black foam into the extended dewshield to kill internal reflections.

Still struggling with dewing of the back of the objective.

The Panasonic TZ7 camera is still failing to capture decent images. This is a snap using a 15mm Meade Plossl. Heavy vignetting, tiny field of view and too high a contrast. Heavily cropped and adjusted in PhotoFiltre. I found a description online of this problem being related to using wide angle camera lens settings. Using a slight amount of zoom may help.

Guy's MkIII thrust bearing.

2011-11-25T03:47:00.001-08:00

Guy has fitted a thrust bearing to his MkIII. A very neat job it is too!

Here is Guy's MkIII mounting after a tidy up and repaint. Note the screwed declination shaft. Suggesting a later model. As does the clarity of the Fullerscopes logo cast directly onto the polar axis castings and the pot base. Guy has fitted a longer pier pipe to raise the mounting for his refractor use. Originally this MlkIII held an 8" Fullerscopes reflector. The brass ring houses the ball, thrust bearing and protects it from the elements. The slow motion drives and motors, shown in an earlier post, have yet to be fitted in this image.

The polar axis is slightly withdrawn here to show the bearing assembly.

The thrust bearing with deep groove steel races and caged balls.

The brass bearing housing with the lower bearing slightly protruding to rest on the polar axis casting. Normally a MkIII would have a PTFE (Teflon) washer sandwiched between the castings to take thrust (end) loads. For lower friction with a heavier instrument the thrust bearing is a useful modification. The thrust bearing adds very little height to the polar axis so will not affect stability. The declination axis "T" rests on the upper brass face.

The MkIII on its new, taller pier.

The "legs" are Fullerscopes Heavy Duty in cast iron. Offering greater stability than the lighter, alloy model.

The MkIII stripped and ready for a repaint on its original, shorter, "reflector" pier.

The MkIII before restoration with its reflector.

An assortment of Fullerscopes parts and accessories. Including a threaded weight, finder/guide scope and VFO drive parts.

Click on any image for an enlargement.

Comments moderation

2011-11-16T05:21:00.001-08:00

I have finally discovered how to have comments notifications sent to me by email. Blogspot had made it so difficult that I had completely missed several comments made on older posts.

If anybody has not had a response to their comments feel free to have another try. I have set all comments to be moderated. I will then be notified automatically whenever comments are posted on any of my blogs.

New Dewshield:

The new plastic dewshield in place on the 6". It is 3 x aperture in length from the cell shoulder. Thanks to its light weight it does not make the tube any more nose heavy than it already was. It looks a bit long but this is due to the short length of the F:8 OTA. It slips over the original, metal dewshield. Which provides support and security.

The material is not stiff enough, on its own, to stay in place with only a small overlap on the lip of the objective cell. Nor could the telescope stay safely parked "on its nose" without the tough, metal dewshield. So the plastic dewshield is removed after use and stored upright on a shelf. It keeps its cylindrical shape well and has a smart, lightly textured finish. I will have to make a long one for the Vixen now. It too has a rather short dewshield for optimum protection on dewy and frosty nights.

The CR150HD6 F:8 beside the Vixen 90M F:11 on the Fullerscopes MkIV.

I now stand on an old beer crate to reach the cradle more easily. The extra weight of the Vixen would otherwise be a bit of a struggle. When set horizontal the cradle is well above head height. Probably 7' above the ground due to the tall but massive stand/pier. Thanks to the beneficial geometry the hinged, open rings accept the main tube and hold it safely without any risk of slipping out or falling. I lock the wormwheel clutches to fit and remove the OTA.

The pictures aren't great but it was a heavily overcast day and almost dusk. I shall take some better pictures when conditions allow.

The polar axis is far too long but I am still deciding whether to add a taper roller or axial thrust ball bearing races at the bottom. The MkIV provides low friction with such light telescopes. Though friction does rise when large and heavy OTAs are fitted.

My idea was to add a screwed collar to the polar casting. Which would allow fine adjustment of end loads on the Polar Axis via a thrust bearing.You can't just add a collar and spring to the shaft itself. Or it would pull even harder on the thrust surfaces.

Some mountings have had a single steel ball taking thrust loads on the end of the polar axis. Because of the very small surface area of contact it reduces friction considerably. One still needs the thrust faces because they offer improved damping and stability over plain shafts.

I have removed a 10lb weight and replaced it with a larger one of 14lb. This compensates nicely for the extra weight of the Vixen. Releasing the wormwheel clutches and swinging the OTAs (gently) produces a similar momentum in both directions. By watching how soon the tubes stop in their rotation (in each direction) about the axes one can soon tell if a reasonable balance has been achieved.

Though not impossible, it is difficult to add the 90mm Vixen to the already mounted CR150HD. There is simply not enough room between the cradle and the tube of the 6" refractor. The Vixen's rings will not pass through this space without releasing the 6" tube from each ring in turn. Suitable packing pieces between the hinged rings of the 6" and the cradle would easily solve this problem. Being able to add the Vixen later would save lifting the pair of OTAs onto the MkIV together.

I managed to find a couple of A3 sheets of the matt black, thin foam to kill internal reflections inside the new dewshield. I may reduce the length of the dewshield to 2.5x aperture. This would give a more balanced look to such a short F:8 instrument. Hopefully without compromising its shielding ability against dew and stray light.

I spent a couple of hours observing Jupiter again. Though beautifully clear at first plates of cloud kept crossing over. There was also a breeze which made my eyes water. Jupiter wasn't high enough to get a really sharp view. I left the scope out while I had dinner. Then found it fully clouded over when I went out again. To finish off the evening I fell headlong over the stand in the dark! Fortunately I wasn't carrying anything at the time. No ill effects.

Click on any image for an enlargement.

November 15-11

2011-11-15T13:24:00.001-08:00

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Dewshield:

I found a coiled tube of pre-curved, black, plastic sheet in a supermarket. Designed as a bin bag support for gardeners. It looked ideal for making an extension dewshield for the 6". Which has always suffered from objective dewing due to its ridiculously short dewshield length. The objective also projects well forward of the shoulder on which the dewshield is fitted. (by friction) Further increasing its exposure to dewing.

The plastic cut easily with scissors provided I held it flat with weights. It had a strong curling tendency. In fact it wanted to coil into a neat 4" diameter cylinder. Ideal for my purpose!

I slid the Celestron dewshield back into the middle of my new, smaller cylinder and taped the lengthways cut edges neatly on he outside with black gaffer tape. Then I removed the metal dewshield and taped the inside. I made the plastic cylinder 18" long overall. It now slides easily over the original dewshield but stays firmly in place.

I put the 6" onto the MkIV mounting and after several hours the lens was still dry. Though everything else was dripping wet with dew. So the dewshield extension is working as intended.

The inside of the plastic is a bit shiny but the dew matted it down. I intend to line the new dewshield with thin, matt black foam from a toy/model shop. I'll post some pictures of the dewshield when it is light enough for photography.

Jupiter:

Having fitted the dewshield I spent the evening trying to take better images of Jupiter. I'd take a dozen images. Then go back indoors to see if I was making progress by viewing them in Picasa3. After each photo session I would take a snap of the monitor to separate the images into groups. Otherwise they all looked so similar it was hard to see where each sequence started and finished.

The TZ7 failed to capture a single image worth keeping. My old Sony DSCP71 produced something useful with almost every exposure!

As usual, I simply held the camera up to the eyepiece and centred it by touch. I took an exposure when there was a bright blob visible on the camera screen.

The images which had potential were put through PhotoFiltre. I played endlessly with Gamma, Contrast, Dust Removal and Colour to bring out as much detail as possible. The four visible moons were captured but lost in the processing.

None of these is particularly good but satisfying enough considering the crude methods I used. The Great Red Spot is just visible on the lower belt, left limb on my screen. I doubt it shows on the blog images. The third image shows it best. The Sony camera has captured all that I could see visually.

I tried a number of eyepieces and even the 2x Barlow and moved the Baader "Fringe Killer" filter across to each new option.

I tried all sorts of settings on the TZ7. Including spot metering and zoom but nothing helped show any belts. Though the moons were well captured as were a few background stars. The trend was always overexposure.

The evening session ended when the inside surface of the objective dewed up. The front surface was still dry. I had swung over to the rising Moon to see if the seeing was any good that low. It was then that I discovered the misted lens surface. The telescopes are parked nose down so the 6" may have collected some fluff on the back surface. I'll have to take the objective cell off and clean the glass.

November dew

2011-11-10T13:32:00.001-08:00

A first clear night for ages pushed me into having a look at a rapidly rising Jupiter in the East. The brilliant full Moon was hanging nearby slightly further to the north east. It was so bright I had no need of a torch when selecting eyepieces from my box.

I had to drag out the massive, welded stand supporting the MkIV. The wheels had sunk into the lawn since the last time I was observing. The pier legs are too big to allow the car to turn safely. So the whole thing has to be pushed out of the way each time I pack up for the night.

My original observing position became completely pointless as trees grew (and grew) around our garden. Ironically the view is clear all round in the drive just beyond the gate. But our neighbours are all afraid of the dark and need multiple bright lights on all night or they cannot sleep.

Somehow I had loosened the drive worm housings so the control paddle had no effect. The worm housings were moving around the wormwheels instead of the wormwheels being driven. I couldn't see this at first despite the bright moonlight. A 13mm spanner to the hex headed screw holding the housings soon solved that problem. The mounting then responded to the paddle controls.

Full moon TZ7, 20mm no-name Plossl, 6" F:8 refractor.
PhotoFiltre improved! Gamma reduction and contrast increase.

I was concentrating on Jupiter. Meanwhile everything was dripping wet with dew. Once, when I glanced through the telescope without the eyepiece and the objective was completely misted over! I broke with convention and mopped the front face with a clean handkerchief.

I have a long, tubular, foam, slip-over dewshield extension but it was hiding somewhere in the shed. It is nothing fancy. Just a roll of black camping mattress and a rubber band. It works amazingly well compared with the stumpy, original, metal dewshield which came with the Celestron CR150HD.

Jupiter proved far more difficult to capture. No visible markings even in the "best" of my hand-held, afocal snaps. I literally held the camera up to the eyepiece and snapped away every time I could see a bright blob on the camera screen. Two belts were clearly visible visually but I completely failed to capture them. I also lost a moon while reducing gamma in PhotoFiltre! This is a heavily cropped shot with considerable gamma reduction to kill flare. Had I the patience I could have gone through the endless TZ7 menus and found spot metering. But I didn't. I had slightly more success with older digital cameras when photographing the planets in this crude way in the past.

What I really need is a sleeve on the focussing mount to give the camera lens something to locate into. This would ensure centring on the eyepiece and also help with squaring-on.

I am always afraid to use a simple camera clamp to the focussing mount. Because the zoom lens might strike the eyepiece under power on camera switch-on. The lens seems to automatically extend for about an inch (25mm) each time the camera is switched on. This gives a fixed clamp no leeway to avoid direct camera lens to eyepiece contact.

These are my best images of Mars using simple hand-held, afocal methods.

A run through PhotoFiltre to enlarge, then adjust gamma and contrast has helped to bring out detail and reduce flare and false colour on the limb.

Each image shows a different face of Mars.

A magnifying lens on the centre of the focussing screen would be useful for astronomy. I can't easily wear my reading glasses at the telescope just to enable me to monitor the camera screen.

I don't own a laptop so can't try my webcam at the telescope. Without a camera clamp or lens, "nose socket" I can't take decent HD astro videos either.

Fullerscopes drives

2011-10-15T08:20:00.000-07:00

I had a recent contact from France, enquiring about the drives on his MkIII. This has prompted me into publishing some details.

To follow the stars, the polar axis on an equatorial telescope mounting should be made to rotate in slightly less than 24 hours . In fact 23Hours : 56Minutes : 04Seconds is the desired period of rotation. The so-called Sidereal Day. A star will pass the same point on the night sky in this time. The polar axis is required to rotate once in 1436 minutes.

A clock running at Sidereal time runs slightly faster than a normal clock. The latter is based on 24 hours per day. Or one revolution of the polar axis in 1440 minutes. 24 x 60 = 1440.

A 24 hour telescope drive is usually close enough. Because a variable frequency oscillator (VFO) will easily allow the motor to be sped up a little. Just enough to follow the stars more accurately.

The Fullerscopes MKIII mounting uses 144 tooth, bronze, worm wheels of about 82mm diameter. The 144:1 gear ratio requires a drive of one revolution in ten minutes on the worm. Or 1/10th rpm.

The MkIV mountings used much larger 6" worm wheels with 359 teeth. A difference of 2.5:1 compared with the MkIII mounting. The MkIV used much faster final drive speeds on their synchronous, drive motors. My own motor is rated at 1/4 rpm. Or one final drive shaft revolution to the worm in four minutes.

The polar axis worm drive is usually provided by a geared, Crouzet, mains, synchronous motor. The motor requires 240Volts @ 50Hz mains supply in Europe.

Some basic MkIII mountings would have only a hand wheel or flexible stalk for a rather laborious hand drive to the worm. As seen in this image of a dual hand and motor drive (above). A slipping clutch in the bronze bush on the left of the worm housing allows the two drives to act independently. The clutch is a simple nylon plug pressing against the worm shaft.

A much better drive option than manual on the MkIII was a tiny, synchronous, gearbox motor. (even without any means of variation to drive speed) This still provided all that was needed for visual observation. (see image) This tiny motor lasted for decades before the internal wiring broke away flush with the motor housing.

I have no idea if any Fullerscopes were exported to lands with alternative voltages or frequencies. They certainly called their best instruments their "Export" models.

The Crouzet motor backplates are always clearly marked with their power requirements and usually their final drive speed on the gearbox output shaft.

The declination axis was also supplied with an identical worm wheel and a reversible motor drive at extra cost when ordering.

Guy's MkIII mounting motors. The RA on the left and the reversible Dec motor on the right.

Only photography really requires greater accuracy in drive speed than a simple motor. The eye can easily forgive an object drifting slowly off-centre in the field of view. The telescope can be easily nudged to bring it back to centre again. While a camera will produce only fuzzy pictures if there is any "wandering" of the image being recorded. Long exposure photographs, particularly with long focus optics, are the most demanding of all!

Modern digital cameras can take very reasonable "snaps" of the Moon and planets. Provided, of course, that there is a drive to keep the object adequately centred in the eyepiece.

Fullerscopes could provide variable frequency oscillator drive boxes with control paddles. These VFOs changed over time. They usually consisted of a large, black box with various sockets and a hand-held, control paddle. The paddle and drive motors would be plugged into the sockets on the box via flexible leads furnished with a variety of "DIN" type plugs.

'Guy's complete VFO drive system with Hz indicator box. The paddle has a rear frequency control knob. Unlike mine which is on the front.

The Fullerscopes VFO box isolated the outputs with relays and transformers to ensure safety at the telescope. It would still be a good idea to provide an earth spike close to the telescope. To earth the pier and mounting together. A wooden tripod would need to be bypassed and an earth taken direct to the mounting.

The "Sync" light flashes at the frequency rate supplied by the VFO. Giving a handy confirmation that it is actually working. The flashing rate can change from a steady glow to rapid flashing when the VFO is set to maximum on the paddle control knob.

Reverse on the Polar Axis motor is simply an off switch. It just relies on the sky overtaking the now-stationary mounting. The VFO cannot provide enough over-speed to achieve meaningful slewing. So it does not attempt to.

Internal components of the VFO box. The two transformers isolate the output. Ensuring no heavy currents can flow in the event of a fault in the motor wiring.

My Own VFO box has 3 and 5 pin motor connection sockets.

In the UK it is common practice to use an RCD device on the mains lead to any electrical equipment which is used outside. Some European countries have only 2-pin plugs without any earth lead at all. Talking to a qualified electrician might be advisable. Particularly when considering the often damp nature of everything when observing under the night sky. Dew and icing is almost always a problem in some places. I have tried a simple test screwdriver on my mounting but it did not "light up".

A scan of an old, 1970s, Fullerscopes catalogue describing the "Skytracker" and MkIV mounting details.

A cropped and enlarged image of the Skytracker text.

Click for an enlargement.

Fullerscopes used the name "Skytracker" for their VFO drive systems. The one illustrated is a MkIV. This has nothing to do with which particular mounting it was used with. The 9 pin socket is for the paddle lead.

The mains socket has a lift up tab concealing the fuse. Do not be tempted to uprate the fuse if it blows! It is there for your safety and that of the electronics.

My MkIV mounting RA motor.

The colour codes for the connecting wires are: Orange to Live and grey to Neutral from the Skytracker lead.The Earth wire is earthed to a motor fixing screw.

These leads are from the output sockets of the Skytracker. Not the mains lead going into the Skytracker box.

My reversible, MkIV mounting, Declination drive synchronous motor.

Here, the central Earth wire from the Skytracker box is connected to the purple motor wires.

The Live and Neutral Skytracker wires are connected to the motor's brown and white wires respectively.

The connecting lead from the Skytracker box to the Declination motor is pre-coiled. This allows the much greater movements typical of the Declination axis.

My control paddle seems less sophisticated than Guy's in some respects.

His has lights to indicate in which direction the drive is being corrected. This gives direct confirmation that something is happening. Which is not always obvious through the eyepiece. Sometimes without a considerable delay.

The large knob on the front of my paddle adjusts the drive frequency up and down on either side of 50Hz. Judging by the flashing light on the large VFO box the top frequency is well over 100hz. It really is very rapid. The light stays steady when I have an exact 50Hz setting.

Push buttons provide a red light for use when the observer's eyes are dark adapted at the telescope.

The other button brings the base frequency of the Skytracker back to 50hz.

Internal view of the control paddle.

Here is Guy's superb website:

http://astronomiedelangrola.pagesperso-orange.fr/index.html

Click on any image for an enlargement.

Lunar eclipse Jun 2011

2011-06-15T23:51:00.000-07:00

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A front was forecast to cross southern Denmark after an earlier promise of clear skies. At 55N the totality was taking place before moonrise. The eclipse would also be shorter than from viewpoints further south.

I spent a frustrating hour standing and staring at a strip of cloud travelling slowly across a very low moon. It was actually hovering between trees on the horizon for the first half hour. At times it was completely clear over much of the sky except where the invisible moon should have been! Only after 3/4 of an hour was there anything to see. Though I was determined not to miss any clearing. By the time it actually cleared only the last of the Earth's shadow was still covering the moon.

The low line of sight was bound to put a lot more atmosphere (clouds) between the moon and my viewpoint compared with anything overhead. The eclipse was more than half over by the time I was able to recognise and capture the true disk of the moon. Until then it was just an occasional dim glow. Or oddly-shaped lighter blobs seen through gaps in the darker clouds. None of the images taken in the first 3/4 of an hour were worth sharing here. The later ones are bad enough!

23:48

23:49

23:52

23:54

23:55

23:58

At midnight the Moon clouded over again so I went to bed. The last shot above was adjusted to bring out the clouds. All the previous shots were gamma reduced to minimise the clouds and the flare they caused.

All Images taken with a Panasonic Lumix TZ7 digital compact camera on Auto2. Usually resting on a fence post to help with the long exposures. Mostly at full, or near full optical zoom. The images were then heavily cropped to get more image scale. The cloud and very low lunar altitude made it a complete waste of time to get any of the telescopes out. Most of the eclipse took place behind a neighbour's tree. So I would have had to drag a heavy mounting the length of the drive. Then have no mains power for the drives.

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May Moon

2011-05-10T14:09:00.000-07:00

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One of those rare occasions when I dragged myself outside to take a few snaps of The Moon. I should have done it last night but didn't. Tonight was cloudy. Last night was not.

The ammoniacal stench of pig shit from the surrounding fields made me breathless. Requiring that I discard my clothes in the hallway at the end of my photographic session at the telescope. Until it rains or they stop overloading the fields with industrial quantities of liquid pig manure nothing will change.

There has been a drought so the weekend pig farmers seem to want to irrigate with foul-smelling slurry and cheap scent instead. We daren't open any windows or the whole house will stink. Our clothes stink just from going outside for a few minutes. We don't even live near a pig farm! The pass us from opposite directions to spread their filth all around us. Welcome to the reality of industrialised, EU taxpayer subsidised, Danish Bacon!

It was this cloudy but still worth persevering for the clearer and brighter moments. There were obvious thermal effects in the image from the hot roof lying beneath the moon. It had been sunny all day with a 72F high. Warmest day this year. I could have moved the mounting but it is very hard work.

I started off with my old Sony P71 for its reliable astro snaps. Simply hand held up to the eyepiece and centred as usual. I used the 2" star diagonal, turned sideways, to help cope with the high altitude of the moon.(otherwise I couldn't see the camera's viewing screen)

Two images cropped and turned to B&W to kill the false colour. I was using my 6" F:8 refractor on the MkIV with the drives running. A Baader Fringe Killer filter was screwed into the eyepiece. (A 26mm Meade 4000 Plossl)

Second image using the Sony P71 on auto.

Now the Panasonic DSC TZ7. I haven't previously had much luck with this camera hand held to the eyepiece. Tonight it seemed to work but the field of view was very small. I tried all sorts of zoom settings without success. Centring the image in the viewfinder screen was much more difficult than with the old Sony. I folded down the rubber eye shield, of course.

Another shot using the TZ7 and a different crop to make the most of the best part of the image. All images were simply processed through PhotoFiltre to improve contrast and detail. Away from the terminator things were always totally overexposed. Increasing gamma and contrast usually made things much worse. Reducing them improved detail on the terminator but made everything much darker.

These were the best from a batch of about 40 snaps. Most of which were relatively useless. It was worth persevering to obtain a couple of fairly decent shots between the clouds.

I'm not particularly proud of these images but wanted to remind myself that fair results were possible using simple means. The MKIV is massive and steady so allows the luxury of hand held snaps without camera shake. The visible detail was exquisite compared with these rather soft, much enlarged shots. Any attempt to use a 15mm eyepiece was usually wasted. I even tried the "Shorty" 2x Barlow but things went very soft indeed. Perhaps I need to try a 2" eyepiece?

Here's the result of further attempts the following night. Still using the TZ7 on auto 2. 20mm no-name Plossl with the Baader Fringe Killer filter. It clouded over at intervals while I experimented with different camera settings for a couple of hours. (including EV adjustment) I have cheated and added a touch of sharpening to these images to make them appear more crisp.

These images are slightly darker than I would have liked. I found that any adjustment to brighten immediately lost all detail in the brighter parts of the moon's surface away from the terminator.

It was a waste of time doing photography while the sky was still bright because it just fogged the image. At this time of year the sky is still fairly light at 10pm. (55N) Still plenty of thermal effects even though I had moved the MkIV to clear the heat rising from the roof. Though the moon had moved well over the roof ridge by the time I called it a night at 11pm.

It shows how light the sky was because I only noticed Saturn a little to the East just before I packed up. It seemed very small and the seeing was rather mobile. A few of its moons were visible. I didn't spend much time on it but the rings looked quite sharp without the Cassini Division being the usual easy target. I was using 60X at the time but going up to 120x didn't help in the poor seeing.

This Danish amateur's observatory is looking smart with a new coat of paint. It enjoys an enviable situation overlooking a lush green valley. Entirely home built the dome contains a home-made 10" reflector. (including the mirror)

After Google had lost my update, in their own update fiasco, I found it cached online and copied and pasted it back. The missing post has not been restored.

Click on any image for an enlargement. Back click to return to the text.

January 11 eclipse.

2011-01-04T01:57:00.000-08:00

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It didn't look promising. It was so totally overcast it was actually getting darker by the minute instead of brighter! Then my wife spotted some brightness through an upstairs window. I grabbed my TZ7 compact camera and ran along the drive to get a clear shot:

This image, believe it or not, was taken on zoom macro setting. I had been playing with macro the evening before. With hindsight I should have taken a solar foil filter but I didn't have time to think about anything but clearing the foreground obstructions. The window of opportunity was less than five minutes before the overcast descended again. Probably just as well because my hands were freezing in the wind.

Cropped from a full optical zoom image. One of only a couple of shots which were not badly overexposed. Reworked in PhotoFiltre to bring out the sun at the expense of the clouds. Without the clouds I'd have obtained no useful images at all. I was watching several British TV news programmes and nobody seemed to be enjoying clear skies.

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Spring has sprung the Moon is riz...

2010-04-22T22:27:00.000-07:00

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Clear skies and improving temperatures brought me outside again with the CR150 6" F8 refractor on the MkIV mounting. The image still looked nicely sharp at 160x though I couldn't see any craterlets within Plato.There were some thermal, rippling effects. Probably because I was looking straight over the roof which had been warmed by almost continuous sun all day.

Here are some hand held snaps taken last night with my old Sony P71 set to infinity. I simply held up the camera to a 15mm Meade SP 4000 EP with the rubber eye cup rolled down. Then aligned the camera to get the maximum field of view on the tiny viewing screen.The telescope had already been sharply visually focussed and the Vixen 2" focuser locked. The drives on the MkIV were running. I normally wear reading glasses so there may be some slight loss of perfect focus for the camera.

A cropped shot of the one above. Plato is the large, dark-floored crater near the top. The sharp eyed will notice a slight greeny-yellow fringe at top left. This is a colour photograph, after all, despite the monochromatic appearance of the lunar surface. A Baader "Fringe Killer" filter was fitted in the eyepiece but visually I could still see violet on the limb at 160x. Though not in the lunar shadows. Quite a pleasing shot for a simple hand-held snap. I chose the best of about twenty shots then downsized it in PhotoFiltre for the blog. Click on the image for a 140kB enlargement.

Occasional vignetting is possible when using hand-held cameras at the eyepiece.

My attempts to use my much more sophisticated Panasonic Lumix TZ7 in the same way as the Sony was a total disaster, yet again. I'm wondering whether there is a setting which equates to infinity lock in the complex camera menus. Or some way of neutralising AF. I can't even get a reasonable image on the 3" focussing screen. Let alone a usable image to upload to the computer.

I must try to persevere with solving this problem because the TZ7 can manage very much higher resolution than the old Sony. It also has IS (Image Stabilisation) I tried several pre-programmed "modes" on the TZ7 but it made no difference. There is no need to experiment with the Lumix at the telescope in the dark. I can more easily try different settings on terrestrial objects with a small telescope on a fixed tripod.

Meanwhile, Venus was a very bright colourful blob just dipping between the local larch trees. Mercury was already out of sight. Mars was just a tiny colourful blob but Saturn was much better. Being slightly higher than last time. The thin black line was even more sharply defined and several moons could be seen. The rings were more obviously open rather than a straight skewer piercing Saturn. The moons were not at all sharp or even continuously visible.
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Near Harvest Moon

2010-04-21T22:27:00.000-07:00

A shot of the moon at full zoom 12x on a hand-held Lumix TZ7 to check the IS. I have no idea what that fuzzy object is at the lower limb of the moon. Probably just a wisp of cloud, but you never know? ;-))

I watched "Local Hero" on TV recently and was surprised to see a Fullerscopes reflector on a MkIV mounting. The instrument was supposedly in the possession of an astronomy-obsessed character played by Burt Lancaster. I would guess the instrument was one of their 10" Export Newtonians with a white painted tube. An interesting choice considering Mr Lancaster's character was supposed to be American and the filthy rich owner of an oil company in America.

I see Skylight Telescopes has another Fullerscopes telescope for sale. This time a 10" F:5 De-luxe reflector on a rather smart MkIII mounting with original pedestal stand:

http://skylight.myshopify.com/collections/frontpage/products/fullerscopes-10-f-5-deluxe

Buyer collects.

And another: An 8" F:6 on a MkIII again on a pedestal stand:

http://skylight.myshopify.com/products/fullerscopes-8-34-deluxe-newtonian

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12" Cass on a MkIV

2010-04-19T03:04:00.000-07:00

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I had an email from the President of the Kent University Space Society seeking advice about an instrument in their possession. The instrument is a rather impressive 12" Fullerscopes, Cassegrain-Newtonian reflector on a MkIV with electric drives and large, Fullerscopes, plastic setting circles. The telescope appears to be housed in a high quality fibreglass dome.

The classical Cassegrain telescope uses a 'fast' concave paraboloid and a hyperboloid convex secondary to provide a long effective focal length in a fairly compact instrument. Fullerscopes used to offer a convertible Newtonian/Casegrain to make the instrument more flexible in application. This particular also appears to have a Newtonian focussing mount. The Cassegrain focuser is also visible behind the primary mirror cell. A simpler form of Cassegrain, known as a Dall-Kirkham, used the same optical layout of concave primary and convex secondary mirrors using simpler curves but could not be used (so well) as a Newtonian.

This instrument has fallen out of regular use and repair due to a lack of skilled personnel to carry out the necessary running adjustments and new observer training. Not an uncommon circumstance in the education field where there is a regular turnover of staff.

I was asked whether they should sell the complete instrument to purchase something newer. My advice was to start with the local astronomical society(s) in search of someone suitably experienced in a variety of telescopes. Hopefully they could offer expert advice free of charge or even make the necessary adjustments if the optical coatings were still usable.

An alternative to selling the whole instrument would be to keep the MkIV to carry a new OTA. Perhaps a compact Schmidt Cassegrain OTA from one of the popular US companies. No doubt savings could be made by buying a secondhand OTA which had been independently inspected prior to purchase. The existing Fullerscopes, hinged, tube rings could easily be replaced with those required for a new instrument.

The complete instrument may be up for sale but would be subject to cancellation if their plans should change. I recommended the UK Astro Buy and Sell small ads website if they wanted to reach the largest interested audience for their sale.

U.K. Astronomy Buy & Sell

It is difficult to see what all the wires and cables do from a photograph but there is a paddle and drives to both axes. The typical MkIV, bronze, 365 fine-toothed, slow motion wormwheels are clearly visible in the images. As are the Fullerscopes white plastic setting circles. A far more useful, if slightly less attractive, addition compared with finely engraved circle mounted on a slip ring on the RA wormwheel. The graduations of which require a powerful magnifying glass and reasonable light to read! The latter should be avoided in any astronomical observatory normally used at night.

If anyone in the Kent area has the real expertise to help with their instrumental problems they might like to get in touch with my contact: howard (at) phillips.fm

Note: I see this instrument and mounting are now both listed (seperately) on UK Astrobuysell seeking offers closing on the 14.9.09 no reserve. Be quick if you want a bargain. Collection only from Kent.

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Rebuilding my 5" F:15 refractor:

2010-04-18T13:15:00.000-07:00

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I had wanted to rebuild my 5" F:15 refractor achromat into a telescope for some time. I made the lens probably three decades ago but it had lain dormant for probably the last half of those years. It needed a new tube, objective cell, mounting rings and a new focuser. The plywood original parts had disintegrated over time. The all brass replacement parts had proved far too heavy for me to lift above my head onto the MkIV mounting. Don't use recycled, artillery shell casings except for a permanently set up instrument!

Once the decision had been made to try again I quickly found a length of 6" galvanised steel, spiral ventilation tubing locally. This proved to be quite lightweight but very stiff though it lacked the flawless beauty of an aluminium tube. Then I made some plywood baffles with dowel stringers while I looked for a pair of modern, hinged tube rings online. I doubled up on 3/4" birch plywood to attach the push-pull cell. I also did a scale drawing to work out the spacing and diaphragm aperture diameters for the baffles. These I sawed out by hand using a fretsaw to rings marked with a screw bow compass. Only light sanding was required to tidy up the cuts.

This telescope has been a bit of an uphill struggle ever since and is taking far longer than I had anticipated thanks to postal and dealer delays. The tube size is not matched by any readily available (or affordable) tube rings. I find this completely unbelievable. Why is there such a big gap in the mass-produced "Skywatcher" type ring sizes just where one would assume a whole range of tube diameters would lie?

I quickly made a crude lash-up of 3/4" plywood just to be able judge the beauty of a long tube on the MkIV. I tried moving it around and took a couple of pictures.

Then I found a pair of 182mm hinged rings for sale on the "UK Astronomy BuySell" free ads website. Lined with thick, black, foam, self-adhesive tape these rings should match my needs nicely. The thick foam liners will absorb the spiral seam of the main tube.

The 182mm hinged tube rings have arrived. Now to find some thick, black, self-adhesive foam.

After struggling for years to insert ring screws into mountings and tighten wing nuts while supporting the OTA in mid air I will never go back to them again. Hinged rings are the only sensible way to go if dovetail wedges aren't available. These old Fullerscopes have nice long (and strong) cradles to carry the tube rings. So it's just a matter of dropping the bare OTA into the permanently attached rings and tightening the screw clamps. The tube is safely resting in the well-spaced rings while the captive clamp screws are tightened. What is more the clamping screws can be loosened slightly to allow rebalancing or rotation of the OTA.

My 90mm Vixen Custom 90 has captive, non-hinged rings fixed onto a matching dovetail. I still prefer to use hinged rings rather than fiddle with long screws through the MkIII cradle. An equatorial mounting cradle with rings already attached just needs to be pointed East/West to give a nice resting place for the OTA while the ring clamping nuts are tightened. I'm really not convinced a short dovetail and declination wedge is the equivalent of a long cradle attached directly to the declination axis for stiffness. The short dovetail on the Declination axis of a modern mounting must be under considerable local stress. This must lead to flexibility limiting the mountings usefulness with long telescope tubes. So the telescope manufacturers build ever shorter instruments despite their optical "difficulties". And so it goes round and around and around.

Meanwhile back at the 5" rebuild:

Now I needed a focuser. My original, 50 year-old, RAS threaded, push pull, brass focussing mount was bought with my paper round money when I was still an impoverished young teenager. (child slave labour was still acceptable back then) The brass focuser was bought for the first telescope I ever built. That one used a 1/2 diopter (2 meter focus) 60mm spectacle lens and some battens to make an "aerial" telescope. So it was about the finished length of my intended 5" F:15 once it has its dewshield added.

Fifty years later I really hadn't a clue what to look for in a focuser. They had already been fitted to the few OTAs I had bought so I had never been in the market for a commercial focuser. I knew I wanted 2" capability and a matching 2" dielectric star diagonal. The latter could share duties on my 6" CR150HD6 Celestron refractor. A (Japanese) Vixen 2" R&P focuser was mounted on my 6" Celestron refractor when I bought it secondhand. Though I wasn't sure if I wanted to move it over to the 5". The Vixen appears below and a big, rugged lump it is too. It's 80mmm (~3.25") focus travel has the capability to be fine tuned via tiny grub screws almost hidden in equally small holes in the main casting. The 2" dielectric star diagonal shown attached was remarkably cheap at £72 + P&P. I just hope it lives up to its promise. The fat end of the Vixen, where it fits the telescope tube tailpiece casting, is ~112mm (~4 3/8") in diameter.

Vixen 2" refractor focuser. (at full extension)

Now I had to look for a modern, commercial focuser and preferably an upgrade without any real idea what to look for. I began to search the many online astronomy equipment dealer's websites and was mazed how many 2" Chinese made Crayfords were available. The prices varied enormously but they all looked much the same with a few expensive exceptions. There were also a number of high end American eyepiece focusing mounts with mouthwatering finishes and claims but they would have run to many hundreds of £s by the time VAT and freight and customs had all been added to the inevitable range of upgrade options.

So I read the glowing reviews of the more affordable options on the popular amateur astronomy forums and was completely taken in. How could something so simple as a Crayford focuser go wrong? A tube, an axle and four bearings? I placed my order for one of the least expensive, 2" Crayford refractor focusers on the online market. Eventually, this is what turned up:

Inexpensive Crayford focuser sans skirt.

The finish was very impressive indeed for the price but the large, fine, ~3" thread on the bottom had me completely stumped. I had been told by the dealer that this large thread fitted a number of commercial refractors and popular SCT rear ends. It was years since I last saw an SCT and almost as long since I looked at an astronomy magazine. The actual focus travel of 56mm wasn't even close to the claimed 68mm either so I wasn't very happy. The GSO refractor focuser had a claimed 98mm of travel which is rather more useful for refractor use. Particularly when Barlow lenses and star diagonals are constantly being added or removed. This compact Crayford focuser certainly seemed smooth enough and the knobs did what they should. Though it would hardly carry loads which the 2" R&P Vixen would simply shrug off.

I spent the whole of the next two days searching online for a matching 3" female threaded adapter to fit the thread on the bottom of this focuser. How was I to know such a thing didn't exist? I emailed various companies without success and trawled endless websites. The images on the commercial websites were always too poor to recognise anything and the descriptions even worse.

Finally I found a well illustrated web page by somebody doing a lube and rebuild of a 2", slow motion GSO Crayford which looked just like mine. Except that it had a removable base to fit a telescope tube. That was the only clue I needed after two days of fruitless searching on the computer. My base was simply missing. That big, fine thread fitted nothing but the unknown manufacturer's own bases!

GSO Focuser

I almost placed an order for a suitably sized base from eBay but I had just emailed the owner of the website to thank him for his very useful article. Fortunately he was a knowledgeable enthusiast and immediately asked me for an image of my new focuser. He recognised my focuser was not a GSO but a cheaper Chinese copy. And what is more no GSO tube adaptor would ever fit it! The GSO has a plain cylindrical stub base which fits into the many different bases and adapters which match all the various commercial telescope tube sizes. I had been sold a "refractor focuser" with a rather short focus travel but without its refractor base. Luckily the dealer had a SCT cylindrical base which I will plug into a turned aluminium adapter flange/backplate of my own making to match my main telescope tube. Now I'm waiting on the post yet again for the SCT skirt. I shall use a 2" fitting drawtube to make up for the lack of focus travel.

The SCT skirt has arrived. The matching threads are shown above. Beautiful CNC work and very nicely finished. Sorry about my fingerprints!

The Crayford focuser now respectably dressed with an SCT skirt.

The 50mm (~2") SCT threaded end of the useful skirt is 82mm Ø. (OD) It offers a perfect flange to attach it to a turned backplate via small screws.

The finish is slightly shinier than the focuser body, but who cares? All I have to do now is turn an adapter ring to match the external diameter of the SCT skirt to the inside ø of my spiral steel main tube. Luckily I found a 24" length of solid 7" diameter aluminium bar in a scrap metal bin a couple of years ago. Equally fortunately I can get this huge bar neatly sawn into useful slices on a band saw by a local engineering firm. I'd hate to have to hacksaw a slice off the bar by hand!

A comparison of scale. 2" Crayford with 1.25" star diagonal & Vixen 2" R&P with 2" star diagonal.

This chapter will be updated regularly as the build progresses. In the meantime I have placed wanted ads online for another 2" Japanese Vixen refractor focuser. Until I find one this little Crayford focuser will probably do fine.

I have turned the adaptor ring in my lathe to a perfect fit in the main tube. (rubber mallet tight!) I was careful to take just enough material from the central stopped hole to obtain a wring tight fit on the SCT skirt. Both ring and focuser would probably stay in place indefinitely without fixing screws. Though I shall drill and thread some holes for fixing screws just to ensure they don't suddenly fall out on a very cold night! Differential expansion of the different metals involved might have this unexpected and undesirable effect.

The new tube rings temporarily fixed in place on the 24" long cradle are show above. It is amazing how the scale of the MkIV shrinks with a long OTA attached. Moving the tube around is very easy, with so much extra leverage, compared with the stumpy 6" f:8.

The black, ring-lining sponge I cut from an old camping mattress was a little too thin to get a really good grip on the telescope tube. So the tube tends to slide through them when it is pointed high in the sky! I didn't much like the look of white, double-sided tape I used either. I'm just going to have to look for some thicker, black, high quality, self-adhesive, sponge strip at the builders merchants. Closed cell foam would be best if I can get it.

Well, finding suitable self-adhesive foam strip proved impossible. So a search began for raw materials from which to cut suitable strips. Eventually I found a cheap garden kneeling mat in dense black foam at a supermarket.

Trials proved that 10mm (~1/2") strip was a suitable thickness to get a snug fit on the tube. After sanding my knife-cut strips, to ensure uniformity all round, I used a high quality, water based, contact adhesive on the foam and rings. I had already removed the original fibrous ring lining material with oil-based, house paint thinners. Which proved an easy and safe solvent. The idea was to expose clean, painted metal to ensure a good surface for the glue to adhere to. Trying to glue to the fibrous ring liner would have greatly increased the chance of the foam liners separating from the ring. The thickness of the new foam inserts easily absorbs the spiral seam of the ventilation tubing.

Now I need to turn an adjustable, push-pull cell for my 5" objective lens. I had better get a slice or two cut from the 7" diameter aluminium bar so I have something to work with. Brass is nice but would make the OTA as nose heavy as a modern Chinese refractor. I'm still not sure whether I want to add a larger diameter dewshield. A proper dewshield looks better than an extended tube of the same diameter. The difference between lens size and tube ID makes the choice optional. I had better make a decision before I start turning an inch or more off the outside of the 7" bar. In the meantime I shall use a plywood cell to speed things up. I have had to shorten the tube by another 10" (250mm) as the dewshield overhang was over 2 feet long once I had achieved focus with a star diagonal in place.

A shot of the 5" F:15 (now with 12" dewshield overhang) alongside the 6" F:8. The extra length of the 5" makes it much more unwieldy to carry around and getting it safely into storage. Conversely, the 6" seems to weigh twice as much as the 5"! You either accept or hate the spiral wound tubing. I prefer it to square sided box, plywood tubes. You make your own choice. I liked the low price compared with buying new, aluminium alloy tubing for this humble rebuild experiment.

Here are a couple of snaps taken with a digital still camera hand held to the 15mm Meade 4000 eyepiece. (no drives running on the MkIV so I couldn't lock the clutches)

The colour correction is excellent and the visual image far sharper than these images would suggest. The Moon was sailing along just above the ridge of the roof which has been heated by hot sunshine all day. The objective has been quickly aligned as has the focuser. Neither are fixed with screws yet. Both could do with more tweaking as there are obvious comatic/astigmatic images on bright stars. The spiral steel tube is slightly oval just where I want the objective cell and this is making alignment unnecessarily difficult. The Cheshire eyepiece showed multiple images no matter how I tried to push the plywood cell around at arm's length inside the tube! I didn't trust myself to try and align with the cell's push pull screws working blind. So I was nudging the cell with my fingertips against the tightness of the oval tube.

This alignment problem will be sorted out in daylight once the parts are safely fixed with screws. A shiny new aluminium tube is beginning to look very attractive right now! The popular irrigation tubing used in the USA isn't available in Denmark. So a new tube will have to be bought from a metal stockholder.

The inside of the tube, the adapter rings and baffles have not even been painted matt black yet. The rings of Saturn, despite the planet being quite low in the sky, were nicely sharp. With the rings in front of the planet a thin, hard black line. Needless to say I am very pleased with the results so far. Except for the focuser. Which fails to move no matter how much I adjust the screws. So it has to be pushed in and out by hand! You get what you pay for. Cheap crap in this case!

I did paint the baffles black but the new, aluminium, objective cell is still clamped in the lathe chuck.The drive belt keeps slipping so I can't get enough torque for a plunge cut.

I haven't done much practical astronomy this winter. It has been the coldest and longest, with the most snow, I can remember. Snow has been lying from before Christmas when we had 16". It lay for 3 months in all! Permanently overcast day and night seems to be the norm. It has hardly risen above freezing for over two months! I can't even reach my telescope stand and couldn't move it through the deep, hard-frozen snow even if I could reach it. My workshop has plummeted to a steady -6C so there's not much going on in there either!

Click on any image for an enlargement. Back click to return to the blog.

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Alejandro's MkIII with GOTO

2010-04-17T04:44:00.000-07:00

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Alejandro is working hard on his MkIII to add GOTO using stepper motors.

He has also added some clever mechanical additions to aid fine alignment of his mounting on its pier. These fine adjustments will aid the precision of his telescope pointing and the accuracy of his drives.

The overall view showing original bronze wormwheel slow motions. The worms in their housings and what I presume to be a stepper motor resting on the workbench beside the mounting

Here Alejandro has used turnbuckles to allow fine adjustment of the polar axis altitude angle.

Some gears are also visible in this image. Presumably these will allow the slow motion worms to be driven by the stepper motors. He talks about pulleys so he may be using toothed belts between the stepper motors and worms.

Here is Alejandro's clever fine adjustment of mounting azimuth by finger power alone. I like the sheer style and neat simplicity of his approach.

Alejandro tells me in his emails that he is working on the electronic circuit board which will allow GOTO using popular sky mapping software. This is an exciting possibility which I wouldn't mind having on my own Fullerscopes mountings. I hope the complications of the circuit board are manageable by a relative novice at such things. We shall see.

I look forward to hearing more details as he makes further progress. No doubt more images will follow when he has the stepper motors in place on the mounting.

Anybody else who has applied GOTO to a Fullerscopes mounting is very welcome to get in touch so that the information can be shared with a wider audience: If anybody just wants to share an image or two of their own Fullerscopes telescope or mounting they are welcome to contact me.

Image size is of no importance since I can easily resize to match the needs of the blog. Since the Windows image resizer toy only worked with XP I am presently using the free VSO Image Resizer with Vista.

Many of these telescopes and mountings date back over 30 years so the present generation of amateur astronomers probably haven't much knowledge of this manufacturer or their products. Patrick Moore had a 15" made by them and there was an 18" German equatorial mounted Fullerscopes Newtonian at Charterhouse in the Mendips in the English West Country.

You can leave a comment on the blog or email me at chris.b (at) mail.dk with any information on Fullerscopes or images of their instruments.

AN UPDATE:

Alejandro has been in touch again and provided some excellent images and fascinating videos of his modified MkIII.

Here the telescope is mounted on the modified MkIII. That is a substantial concrete pier.

A close-up of the MkIII showing the worm gear and toothed belt reduction drive from the stepper motor.

The modified MkIII seen from the south.

A short video showing the toothed belt driving the worm.

And another video showing the mounting moving in both axes to the software control.

Click on any image for an enlargement. Back click to return to the text.

Another 3" Fullerscopes Refractor

2010-04-16T14:27:00.000-07:00

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Yet another 3" Fullerscopes refractor on a MkIII mounting. This one has the optional cast tripod base with the long wooden legs fitted. Note the height of the eyepiece. No grovelling on your knees with this one. Not like the "modern" refractors which assume you are a dwarf or have a dry moat dug around your mounting. The combination of black wrinkle paint and polished brass would look good in a drawing room. Yet it would be be very easy to carry it outside to examine a bright planet, the Moon or even the Sun when fitted with a safe solar filter over the objective lens. Eyepiece solar filters are extremely dangerous and may explode when exposed to the focussed heat of the sun. If the shattering glass of the filter does not instantly blind the observer then the focussed beam from the objective falling on the unprotected retina certainly will.

A general view of the instrument on its sturdy MkIII mounting and tall, braced tripod.

Look at the beautiful proportions! The length of the dewshield is appropriate and will offer protection on a night of heavy dew. The main tube is of classical length rather than the stumpy examples common to more modern instruments.

The all brass finder and focussing mount are classical touches. Note the excellent stand-off from the main tube of the finder in its tall, cast finder rings with centring thumbscrews. No squinting along the tube with your nose or cheek pressed against freezing cold metal required here. A glance at any of the fine refractors made by the greatest makers show similar finder rings. Many modern instruments could learn much from studying this instrument and others from a bygone age.

The original bronze slow motion wormwheels and steel worms are provided with flexible wands to allow easy centring of an object in the field of view from the eyepiece. The sturdy MkIII mounting would offer very stable viewing at the highest magnifications this instrument can manage. It is probably capable of upwards of 150x or 50x per inch of aperture.

The all brass focussing mount is furnished with an internal rack and a beautiful brass focussing wheel in classical refractor style reminiscent of instruments made one hundred years earlier. A star diagonal is fitted into the brass focussing tube for comfortable viewing at high angles of altitude.

The original black wrinkle paint is in superb condition. This particular MkIII even has its own model and the manufacturer's name resplendent on the polar casting. Letters also appear on the tripod base. My guess is that it also reads "Fullerscopes".

The three inch aperture, long focus, achromatic objective in its brass or gunmetal cell. A lens with a classical focal ratio will offer sharp images almost free of false colour.

Despite its age this instrument is still very desirable and would make an excellent solar telescope when fitted with a full aperture solar filter. The star diagonal will offer sharp, upright views but mirror reversed.

Once again I must thank Richard at Skylight Telescopes for these superb images.

www.skylightelescopes.co.uk

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Staying warm:

2010-04-14T02:29:00.000-07:00

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Much of the following may seem patronising to those used to cold climates. As with all things you are completely free to ignore my advice. I have decades of experience in walking, climbing, cycling and camping in winter so I have learned the hard way. I started out by making my own mountain jackets and winter sleeping bags out of my old, Terylene wadding, summer, sleeping bags. Prices for serious winter gear were beyond my pocket back then. The downside was the the sheer weight and bulk of my kit and the unbelievable size of my rucksack! Now many sports clothes shops seem to sell high quality down-filled clothing and sleeping bags.

Temperatures are very subjective and only meaningful to the person experiencing the conditions. -3C with a biting wind in the UK is kid's stuff compared with Continental Europe or parts of the USA. That doesn't mean that the UK observer doesn't feel the cold and probably needs advice on dressing appropriately more than any other nationality. It does seem to be a native blind spot. While those blessed with Arctic conditions every year know exactly how to dress properly to match their own conditions.

Many amateur astronomers complain about being cold at the telescope. Yet there is absolutely no reason why they can't be toasty warm down to -10C with very little effort or expense. It's no use going out in a pair of jeans and a denim jacket expecting to be comfortable in cold conditions. Staying warm means you need both both insulation and protection from the wind. Insulation needs lots of thickness to function well by trapping still air. Still air is an excellent insulator. Moving air will chill you faster than much lower temperatures in still air thanks to something called the wind chill factor.

Wind proofing is best when it isn't also completely waterproof. Waterproofing usually means a high risk of condensation on the coated inner surface of the nylon shell if you so much as move a muscle. You aren't likely to be daft enough to try and observe during heavy rain so the idea is to insulate yourself with thick wadding or down within a light windproof shell. The shell is usually damp proofed, very finely woven, nylon cloth. Most down jackets I have come across seem to have a decent enough outer shell without adding another windproof jacket on top. Wearing anything tight or heavy on top of down clothing will compress it. Robbing you of its superb insulating power.

If you smoke you will soon regret wearing "proper" winter clothing. Because sparks from your cigarette or pipe will burn neat holes through the thin cloth like a hot knife through butter. Your precious down will start to leak rapidly through the holes you've made unless you patch them well and immediately. Good luck with that! So if you do smoke you'd better put a light cotton jacket over your expensive nylon shell. Did you know that smoking spoils and slows dark adaptation? Thought not. The flash of a match is unlikely to help you see faint fuzzies either.

Down filling has the advantage of allowing free and easy movement however thick the insulation. It also compresses really well. Down to almost nothing if you need to store or carry it. Thick wadding is often too stiff when you want to lift your arms to reach up to focus or make other adjustments. I won't give a wadding jacket house room any more. It's down every time. Smokers should seriously consider wearing wadding filled clothing to avoid the inevitable down loss from self-inflicted damage.

Down is usually very much lighter than most kinds of wadding and snuggles naturally around you. Being so flexible and compressible one can wear one down jacket inside another if conditions demand it. The advantage here is that even more still air is trapped between the two garments. The necessary seams to keep the down under control and evenly distributed are also very unlikely to overlap. So two thinner and lighter jackets can be as warm as a good single jacket.

The two jackets will be heavier and stiffer than a top quality mountain jacket but still offer superb warmth and flexibility in temperature control. The same goes for a down waistcoat under a down filled jacket. This is a really cosy combination I use a lot of the time. The problem with these superbly insulated clothes is staying cool enough if you exert yourself. Thankfully most observing means standing or sitting around for long periods with stable but comfortable temperatures inside your clothing.

Being a lifelong recycler and now living in a cold winter climate I keep my eye out for good used examples of down clothing in charity shops. I rarely need to pay more than £5-7 ($10-15US? Or equivalent) for superbly warm down filled jackets in clean, as-new condition. Having collected together a great variety of down jackets, insulated trousers and waistcoats I now have a wide choice. I dress depending on outside temperatures, wind strength and my subjective need for warmth. All of which vary widely.

Who cares about the slightly loose fit or the bright colour of the down/duvet jacket I'm wearing when I'm standing completely alone out on the lawn in my pitch dark, rural garden? Do I care that I look like the Michelin Man? No, I don't and nor should you. Dressed appropriately you will actually begin to enjoy the cold crisp nights and cool evenings at the telescope. You will spend more time observing. Instead of staying indoors to commiserate with other people complaining about the cold on the astronomy forums!

Thank goodness duvet jackets are now a common fashion garment thanks to their widespread use in the USA. When I started wearing my first, fat, down, mountain jacket in my youth people would stare at me on the bus. Remember the Back to the Future reference to the "life saver" when the hero was wearing a down waistcoat! A fashion garment in the wrong time period? My jacket was actually so warm that I usually had to take it off to stop myself from sweating buckets before I reached my destination. I was always experimenting with thermal underclothing back then to avoid the chilling effect of sweating indoors then going outdoors into the cold. It is actually far easier to simply take the jacket off indoors then put it back on when it is really needed! You can't argue with simple physics.

Down choice: Look for the vital garment label: Sometimes inside the collar or usually low down in the side the body lining under a sleeve position.

Given a free choice look for pure, thick, goose down rather than duck down of the same thickness. Goose down is warmer than duck for the same thickness. Look for wall quilting. Or double, overlapping quilting. Much better than the cheap sewn-through panels which are cold at the seams you see on cheap, fashion jackets. Look for high percentages of down to feather. Or pure down if you can find it. Feathers are very poor insulators compared with pure down. The feathers can easily be felt through the cloth shell with poor quality fillings. Squeeze the garment between your fingers to check for stiff quills. I wouldn't buy a lumpy filling like this at any price.

Pure goose down is very expensive when new but you should be able to find a good but very affordable jacket if you regularly monitor a number of charity shops in your area. People get fed up with the colour or the style and just give them away to charity shops. Students are fond of them so if you live in a university town you might have more luck in your search. Or more competition for the good stuff!

Older down jackets tend to start losing down from the seams which will cling to your black fleece wear. This may explain the large number of jackets I see in charity shops. Who cares if you look like you've been rolling in the snow as long as you are warm at the telescope? Give a secondhand down jacket a shake to see if it is shedding down badly before you decide that you can't live without it. One or two bits of down floating about is okay. A cloud of down is just not worth the trouble.

Beware that the law in some countries allows quite high percentages of feathers to down to be still called down on the label. Down has the unique ability to expand as it warms from body temperature. The superb insulation of pure down actually grows thicker when worn. Wadding just does what it does and slowly gets thinner from repeated compressions.

A down filled duvet is a superb choice on your bed at home compared with the stiff slab of wadding which falls off onto the floor all night. The down filled duvet wraps itself cosily around you. Closing off those chilling air gaps without weight. The same goes for down sleeping bags.

I managed to tempt my wife out of doors in a light frost to take the posed photograph below. No, I'm not the invisible man wearing a pink rubber glove! I deliberately obscured my face to maintain my privacy. Under all that down gear I'm as slim and as handsome as you are.

If you can't or wont buy at a charity shop and live in an area where there are climbing shops you could check out the down jackets there. Price tends to follow quality and lightness. The absolute best, super quality down fillings, light but incredibly tough shell and the way the filling pockets are arranged inside the jacket walls are inevitably expensive. These jackets have to withstand high altitudes, very low temperatures, very high winds, tearing and abrasion from climbing rock, ice and ice axes, crampons and ropes while allowing complete freedom for the wearer.. Things you hopefully won't concern yourself with on the back lawn. (where you usually have the choice of going back indoors to live another day!)

Compare prices at the climbing/outdoor shops with the rather heavier jackets sold at the high street fashion/sports shops. See if you can manage without the top quality mountain gear which always attracts a premium in price. Your wallet will obviously dictate your choice. Just don't buy anything too tight however rich you are! You need room for lots of clothes (or at least down waistcoat) underneath on the very coldest nights. Nowadays you can shop online but be sure of your sizing or ensure you can return goods which are too tight. A tight down jacket is worthless and will actually self-destruct as the seams are constantly stretched by your movements. You should hardly know you are wearing a good down jacket as it so light, snug, warm and comfortable.

I always wear a floppy Thinsulate (tea cosy) hat while observing because it is light and non-allergenic. It also stays on my head even if bend down to pick something up. Wool hats make me itchy. A soft hat can be adjusted to cover cold ears when it isn't quite cold enough for a balaclava. A lot of heat is lost from the human head in cold conditions. A baseball cap is a real nuisance at the telescope at night. It isn't remotely warm and the peak is always knocking against the finder. If you reverse it, street-cred style, the peak lifts the cap off your head as you tip your head back to look through the eyepiece. Save the baseball cap for solar observation where it offers some shade.

A balaclava is one of the warmest additions to your observing wardrobe in cold, breezy weather. Balaclavas can be pulled down to protect the neck and ears or worn rolled up into a floppy tea cosy. Sometimes I wear mine with the Thinsulate hat as well for extra warmth. Or both under the thick, down-filled hood of one of my duvet jackets if it is really biting cold and windy. Flexibility is the key. If you find yourself getting too warm while carrying your equipment across the garden to a new spot you can quickly remove your headgear for a rapid temperature loss without chilling your body.

Forget all about cold jeans even with thermal longjohns underneath. Fleece jogging trousers (or track suits) are available in many thicknesses and are far warmer. You can wear two pairs if sized appropriately. A slim, snug pair under a baggy pair offers superb warmth and windproofing without limiting your movements.

Then there are the light, wadding-insulated, over-trousers to wear on top of your long fleece pants. I'm not sure if these are intended for hardy golfers but I have accumulated several pairs to swap around depending on conditions on the night. Loose and baggy is best with these and it isn't a fashion parade anyway. They usually have elasticated waists so stay up even when bought deliberately oversized to fit over fleece trousers. Down filled trousers can be very warm but are easily compressed when sitting. Wadding is more resistant to compression and can be bunged in the washing machine without second thought. Down needs far more care in washing.

I have several down waistcoats which are valuable for extra warmth and offer great flexibility in heat control. I can open my jacket if I get too warm and the waistcoat maintains body heat. Or I can open the waistcoat as well to cool off rapidly when necessary. I can keep eyepieces in the waistcoat pockets if conditions are leading to rapid misting. The eyepieces are then rotated through my right jacket or waistcoat pockets. My compact digital camera always sits in the big left hand jacket pocket to avoid internal condensation. Developing habits like this ensure nothing expensive gets broken by dropping several things at once into a deep pocket.

Gloves are a complete pain in the "wotsits" because they deny fine dexterity for tightening those daft little draw tube or star diagonal eyepiece clamping screws! I am usually warm enough to do without gloves because I protect my core temperature properly. A warm body does not draw heat away from the extremities to survive. So your hands and feet usually stay nice and warm. Beware of very cold metal welding itself to the bare skin of your fingers though! A little moisture is the danger here. Plastic focussing knobs are actually far more practical in winter than fancy, expensive metal ones! Rubber sleeves on the focussing knobs no doubt help here but why bother when plastic is so superior? Down jackets usually have large hand warmer pockets anyway once you have the object centred in the field of view.

Hiking boots are better than ordinary shoes and far better than trendy trainers. You need plenty of room for thick winter socks so don't buy boots that are too tight. It's not a fashion parade alone in the pitch dark. Rubber Wellington boots aren't ideal but may be useful in deep snow. I find them too cold.

Staying comfortable is the trick. Get too warm and you'll sweat too easily under all that insulation. Which means it will feel like an ice cold bath when your own sweat suddenly condenses against your skin through your wet vest or t-shirt. If you feel yourself getting too warm you must open up your jacket, take off your hat or lose heat somehow. Don't ignore the first feelings of getting too warm or you will suffer far more than simply being too cold.

Going back indoors to download your camera, or to look at a star map, will cause you to rapidly overheat. Make a habit of taking off the jacket and hat or you'll feel really cold when you go back out again. If you start to feel cold when outside do some exercises in small doses until you feel pleasantly warm but never hot. You must avoid sweating at all costs so your undergarments stay dry and warm.

Keeping the telescope comfortable:

I find anything below about -10C begins to make life difficult at the telescope. Many plastic insulated cables stiffen up in the cold. The slightest breeze rapidly increases the wind chill factor. This is where observatories score highly against standing out on an exposed lawn or yard because they offer shelter from the wind. A dome reduces your own radiation to the night sky and offers the most wind protection. They also have thermal issues from boy heat escaping through the open slit. Just where you are trying to look through with your telescope!

A roll-off is better still and provides shelter from the wind. Even a slight breeze increases the wind chill factor dramatically. If you have a permanent site in the open garden it would be worth putting up a few fence panels and strong posts to shelter you from the prevailing wind. Hedges take too long to grow into a decent shelter belt and are poor windbreaks in winter anyway. I know this because my garden is surrounded by tall trees and tall hedges and it is often still very windy out there.

Cold eyepieces may steam up from the moisture of your eye. Or dew up from your breath if you don't deliberately direct it away. When you are breathing through a balaclava it isn't so easy to keep the eyepiece clear of dew. I pull my balaclava down under my chin and breathe downwards through my mouth to avoid fogging the glass. Keeping eyepieces in a pocket allows your body warmth to keep them far warmer than in an open box or rack. On dewy bights an open rack or box will soon get very wet.

Residual moisture inside the OTA can fog up a refractor objective inside where it can't easily be reached with an electric hair drier. This has ended a couple of my very cold observing sessions in the past. A good long dew shield helps to keep the glass just above the ambient air temperature. Most modern refractors have woefully inadequate dewshields. I'm sure they are styled like this just to make them look short and stubby like the ultra-expensive Apos. (Apochromatic refractors)

Just roll some black, closed cell, camping mattress around the original dewshield to double its length and hold it in place with a bungee, string or even thick rubber bands. The foam will act as an insulator as well as improving your telescope by having a proper light and dew shield. I'm often surprised how my neighbour's security lights will fog the field of view. Even when the telescope is pointing away by quite a large angle. The matt black paint inside the skimpy, Chinese dewshield of my Celestron 6" refractor is obviously not all it should be! Thin, black, closed cell foam from craft shops is good value when used as an anti-reflection surface inside the dewshield . No doubt contrast could be further improved by applying it elsewhere inside the OTA.
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A 3" Fullerscopes refractor.

2010-04-13T09:33:00.000-07:00

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Here is another Fullerscopes telescope. A 3" refractor sitting on a sturdy MkIII. The mounting has the optional cast pot base fixed on a tall pipe pier fitted with the standard, light-alloy, Fullerscopes, cast pedestal feet. Ready to use in an instant without any cooling down required. No grovelling on your knees to reach the eyepiece when the telescope points at high altitudes. No wobbly, undersized, aluminium tripods designed by somebody who has never seen a real telescope. Let alone actually used one. Those who have designed the inadequate mountings and tripods of the 1990s should be forced to use them as penance for their utter ignorance of what really matters under the night sky. Rock steady stability, easy pointing and following are the only the most desirable features. What about the eyepiece always being comfortably placed for the observer regardless of the position of the object under scrutiny? One hundred years of nightly use of their pathetic wares is punishment enough for those churning out today's astronomical tat. Do they think there is nothing above 30 degree altitude worth looking at? A star diagonal is a vital component with any refractor but assumes you can still reach the eyepiece. And do so without silly contortions or constantly muddy knees! Listen to ignoramuses on the astronomy forums telling you that refractors are neck wrenchers. You'll instantly recognise the owner of a modern instrument.

This size of telescope was a very desirable instrument in my youth. A 3" refractor was considered the minimum size for a serious astronomical instrument. Yet a remarkable amount of serious work was carried out with instruments of this size and smaller apertures in the 18th and 19th and well into the 20th Century. Smaller apertures were often used in the days before Chinese mass production brought aperture fever and relative affordability to the ordinary amateur astronomer.

The vast majority of these older instruments were of a so-called "classical" focal ratio. Meaning that they had a very long focal length relative to aperture. F:15 was considered normal. F:18 not that rare. Some instruments ran to much longer focal lengths with F:Ratios well beyond 20:1. The aim was to improve the image quality by reducing the natural false colouration of achromatic aberration. This cannot be avoided in an ordinary flint and crown doublet achromats. Only special dispersion glasses like the so-called ED glasses and the costly Fluorite can remove false colour almost completely. The "slower" the optical system (using the photographic term) and the smaller the aperture the less false colour would be seen in the image by the visual observer using an ordinary achromat. Photography was not a serious pastime with such instruments and the field of view was very small anyway. Film was much too slow or too grainy to capture the relatively dim images on extended objects like the Moon and planets. So they were used visually almost exclusively. Usually they perched on a tall, sturdy, well-designed, wooden tripod. Often fitted with an altazimuth, offset fork rather than an equatorial mounting. The latter was usually reserved for the larger instruments. Which were not so easy to move about and so needed and enjoyed a stable cast iron base for their heavy steel, tin or brass tubes of the time.

What most of these refractors had in common was the ability to push the magnification to the maximum possible for the aperture without the image "breaking down" into a fuzzy ball of light. 50 magnifications (power) per inch of aperture is considered a reasonable maximum for most instruments. A good, long focus refractor might be pushed to 100x per inch of aperture and sometimes well beyond on a good night when the air is perfectly still. The best objective lenses were slowly polished on pitch using the finest optical rouge to obtain a flawless, highly transparent, spherical surface. No doubt the Chinese objectives of today are polished at the highest possible speeds using paper, fibre or cloth laps and rapid but coarse cerium oxide polishing compounds. Thus leaving a much rougher surface due to surface heating effects. I'm a bit out of touch on modern, mass production optical fabrication. So I may be completely wrong.

I watched elderly optical workers just before their retirement back in the 60's and was amazed at their skill and dexterity. They knew by instinct when a surface was no longer spherical or was growing too short or long in radius of curvature and adjusted accordingly. Their movements were precise and entirely automatic with absolutely no excessive gestures or wasted energy. It used to be said that optical workers could be followed home by the trail of red rouge they left in their path. These highly skilled gentlemen were already using Cerium Oxide by then.

Smaller apertures have another serious advantage over larger instruments. They look though narrower "beam" of thermally unstable air than a larger instrument. This makes the image more stable and able to be used with higher powers in inferior "seeing". Which might even make a larger instrument unusable on some nights. For double and variable star work these small instruments were, and are, still fine. Stars do not change in size depending on the size of the telescope. No matter how large you make the telescope or how much they magnify. These small refractors could give a nice view of the moon or the planets. Though it takes a bit more aperture to get really large, sharp images for the illusion of hovering above the Moon's surface. For double stars the high magnification was necessary to split close doubles with such a small aperture. The telescope can magnify the separation between double stars but not the size of the stars themselves. There is a limit on how close a double a particular instrument aperture can manage. Fuzzy star images make separation more difficult because the stray light blurs and bleeds into each separate star. Closing the gap between them. Instead of a nice clean separation with distinct stars and inky blackness between them. Experts still use selected double stars to confirm the optical quality of telescopes under test.

Just look at the length of that dew shield! It fits on the front of the objective cell where it should be. Not hiding the cell half way down the dewshield. As is very common of many commercial refractors today. They do this just to give the illusion that the telescope is shorter than it really is. Perhaps even suggesting it might be an expensive APO? What a total con! What a cheap conjuring trick! The objective gets covered in dew within half an hour of going outside. Believe it or not, specialist firms now make real dewshields to properly protect the glass. By making them long enough and light enough to actually do their intended job. How pathetic is that? A dewshield which isn't anything of the kind? Some dewshields are made of steel which is heavy and unbalances the telescope tube. Making it look as if it has slipped through the rings to finally stop at the cell before it could slip right through onto the ground. Have a look at my 6" F:8 Celestron on the MkIV if you want to see a perfect example of this horribly ugly imbalance. Now look at the 3" and 4" Fullerscopes refractors show here. They stand tall and proud on their mountings like the giant refractors at the great observatories. The shorter the overhang at the eyepiece end of a refractor the smaller distance it covers as the telescope moves through the entire visible hemisphere of the sky. That is worth having because you don't need to keep shifting yourself around the mounting. Wearing out the grass over a large circle. The shorter the overhang at the business end the lower the pier or tripod can be without the eyepiece "scraping on the ground". So the modern refractor is not only a double sales con to impress the beginner. It shoots itself in both left feet. Or all three if you prefer. By making the eyepiece far too low for comfort, dewing up rapidly and making the telescope look downright ugly instead of incredibly impressive. Everybody loves a tall refractor soaring high into the air. It looks like a real astronomical telescope is supposed to look. How does yours look?

Manual slow motions are fitted to both axes on this mounting. Only the polar axis has a flexible control. These universal "stalks" are easily available from astro-equipment vendors if it was thought desirable to add one to the declination axis. Note the solid bronze slow-motion wormwheels. You'll be lucky to find hard-wearing bronze wormwheels on any mounting made today that doesn't cost much the same as a new car!

A small synchronous motor could easily be fitted to the polar worm shaft to enjoy relaxed viewing. I find a motor drive makes observing so much more enjoyable. Instead of having to move the telescope by hand all of the time. Particularly at high magnifications. When an object is rapidly crossing the field of view it is difficult to keep it on the "sweet spot" in the centre of the field of view. You don't even get a chance to focus your eye on the object to see the fine detail before it has gone right out of the edge of the field. A motor also allows you to leave the telescope to follow an object while you do something else. Like downloading your latest images into your computer from your digital camera to check your results so far and warm up a bit indoors. My MKIII drive motor died recently just as I wanted to use the mounting to record a partial solar eclipse. I was amazed to have caught anything with my digital camera while constantly having to turn the slow motion control by hand. Or even nudge the tube between taking my hand-held "snaps". The results of my solar eclipse photographic endeavours can be seen in another chapter under "Transits and eclipses".

The instrument looks beautiful in black wrinkle paint with polished brass fittings. Fullerscopes used to offer an "Export" model of each of their telescopes in this very desirable finish. The brass focussing knob on this 3" has been moved to the lower part of the main tube. A popular position on many classical refractors from the golden days of "brass and glass". I'm not sure about the length of the Polar Axis on this instrument. Perhaps the shaft has been swapped for a better one? It loks as long as the Declination shaft ought to be. My own MkIV has an over-long polar shaft because I haven't cut it in case I need the extra length for something.

The brass finder telescope in its tall, cast, adjustable mounting rings sets off the instrument perfectly. None of your modern spring-loaded finders flopping about as the main instrument is moved. Plenty of room to use the finder wherever it ends up relative to the main instrument as it is moved around the sky on its German equatorial mounting. Modern finder rings are often far too close to the instrument and lose their view simply by being blocked by the mounting. Or cause such gyrations of the neck that it might as well not be there. A good stand-off distance is essential for finder comfort and practical functionality. Look at the great refractors of the observatories and see how tall the finder rings are on those beauties. With two matching finder rings you can also set-off the finder to a nearby star. For example when you want to photograph a dim object which is invisible in the smaller finder.

White gloss painted tubes seem to have become the latest fashion in telescopes. I suppose it makes them easier for the clumsy to miss them in the dark. My tastes are from a period when black wrinkle paint was a sign of luxury. The manufacturer showed he was going the extra mile instead of using plain gloss paint. Wrinkle paint does not show fingerprints, scratches or chips so readily either. It was hard baked on and lasts better than gloss. (or Hammerite for that matter)

This MkIII is fitted with the original, large, white, plastic, setting circles. An excellent combination of clarity, longevity and nice, big graduations. No magnifying glass and bright torch required here to point the telescope at an object using the Right Ascension and Declination coordinates. Look at the size of those setting circles compared with the microscopic graduations seen on small bands fitted as an afterthought to many a modern mounting. Notice the size of the shafts and massive yet lightweight castings compared with the tiny things on offer with many telescopes today. I wonder how many modern mountings will be valued as useful bases for telescopes in 20 or 30 or 50 years time. There is simplicity and strength here allied with function. Many modern mountings suggest the triumph of appearance over functionality and stability. You'll not find the owner having to modify a Fullerscopes mounting just to make it stable enough to use with the usual oversized instruments sold today. Sand filling short, wobbly, aluminium legs and removing useless Chinese grease is not required.

Set up on a tall pier a refractor makes perfect sense in the observer comfort stakes. How many forum threads have you read about adding weights to the eyepiece end of a modern refractor OTA? Just to be able to look through the instrument without having to empty the swimming pool or goldfish pond. Or digging a deep hole. Anything to bring the observer to a lower position so they could actually look through the eyepiece without lying flat on their back on the wet grass. And they call this progress? Don't moan to me about your wobbly knee-high, aluminium tripods. While simultaneously sneering at tall wooden tripods as being "too old fashioned". Nobody can see you observing in the dark whatever your tripod material. Anybody using a tall pier or tripod is going to be doing a heck of lot more astronomy than you with your highly-polished, metallic jelly. And how much did they charge you for that crappy tripod anyway? You could build a decent, tall tripod out of quality hardwood for a fraction of the price. Or sink a simple pipe pier into the lawn. Get yourself an adjustable height chair and you can observe in perfect comfort for hours on end sitting down. You'll need a properly balanced refractor fitted with a star diagonal of course. You wouldn't be daft enough to buy something you couldn't actually use on the whole sky, would you? That wouldn't be an astronomical refractor. It would be a terrestrial. Or a common or garden bird watching telescope but with an inverted image. Wouldn't it? That's what I thought too.

Protected from the elements a refractor and Fullerscopes mounting will give decades of enjoyment exploring the night skies. It becomes an heirloom instead of an irritating burden to be discarded as soon as the doting grandparent goes off into the old people's home. No need to cover and worry about dew and scratches on delicate aluminised reflective surfaces with a refractor. A refractor will last virtually forever without deterioration. The glasses used varied a bit but only slight yellowing occurs over the centuries with some of the the older glasses. They tended to be designed to achieve best focus more towards the yellow. Instead of the yellow green of today's computer-optimised prescriptions. We may be spoiled rotten by cheap APOs and large achromats these days but the sharpness of the image seen through a fine, small refractor is well worth seeing. Perfect star images on either side of focus with textbook diffraction rings are to be expected. A lightweight, compact tube to carry out to the pier or tripod. Where the mounting is already set up and aligned on the Pole Star for instant use. Open the rings. Pop in the telescope, tighten down gently on the thumbscrews and you can start observing immediately.

The images in this chapter were kindly supplied by Richard Day at Skylight Telescopes of London. A vendor of collectible, quality instruments for the discriminating observer who is not fooled by this year's glossy, full-colour advertising spread in the popular magazines. I'm beginning to sound like an advertising man myself. As well as an opinionated, old .. observer.

www.skylightelescopes.co.uk

BTW: The beautiful instrument illustrated here has been sold.

The images in this chapter are not yet clickable for enlargement. Patience will be rewarded.

Fullerscopes 4" Refractor.

2010-04-12T05:05:00.000-07:00

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Here is a complete 4" Fullerscopes refractor on a MkIV mounting sitting on a heavy pipe pier with original cast iron "heavy duty" feet.

Fullerscopes usually offered their 4" refractor on the MkIII. This one enjoys the great pondus, stability and sheer class of the timeless MkIV.

A closer look at the 4" OTA (Optical Tube Assembly) on the MkIV. This achromatic refractor is longer than many of the Chinese offerings of today. Theoretically this provided sharper images with less chromatic aberration and coma. Another advantage with long focal lengths is the ability to use comfortably long focal length eyepieces while still enjoying high powers. This in turn offered increased eye relief without one's eyelashes smearing the surface of the eye lens or obscuring the edges of the field of view.

Now there's a nice point of view! Lots of polished and lacquered brass and black wrinkle paint. Fullerscopes made the classical rack and pinion focussing mount in the same style as the great 19th Century makers. The heyday of brass and glass when makers vied with each other to produce microscopes and telescopes for those who could afford them. The upper and middle classes were the only customers who could afford such luxuries back then. Beautiful refractors like that shown here would grace stately homes and doctors, lawyers and bankers detached, country homes. This may not have been strictly true of Fullerscope's products but they still required a considerable investment for that time. Prices for refractors have fallen dramatically in recent years as Chinese products overwhelmed home markets for these instruments.

These much earlier instruments could also be found in the fee paying (public) schools of the wealthy. The telescopes were often housed in domes like the one shown above which protected a 5" classical refractor in the grounds of a public school. An all brass 6" refractor was stored at the same school but had suffered a broken crown element in the objective lens. The workmanship of the entire instrument was of the quality which only the very best makers could manage. With lots of intricate brass and bronze castings all skilfully hand finished and deep gold, hot lacquered to maintain the superb finish for a lifetime and well beyond.

Another view fr0m the business end of the 4" Fullerscopes refractor. The counterweight might be improved to be more in keeping with the perceived quality of the instrument by fitting a simple, cylindrical, bored turning in steel or iron. A few minutes work for anybody with a lathe and the raw materials.

A closer view of the mounting showing the 6" bronze wormwheels and slip-ring RA circle with metal pointer. These are presumably of a later date than my own MkIV. The main castings were designed to maximise stability by using widely spaced sleeve bearings supplemented by large surface areas on the thrust faces. PTFE sheet was used to reduce friction between these faces. Offering a light, buttery smooth motion without backlash provided the telescope is not too massive. The MkIV could carry up to 15" reflectors but friction may have increased beyond the comfort level when fine pointing the telescope by hand. These castings look rather rough suggesting that they have been cleaned up with a very coarse file by somebody in a hurry.

The large plastic knob jutting from the declination casting actuates a simple clutch via a long screwed rod. This forces a nylon plug against the inside of the relevant wormwheel. There are two knobs. One for each axis. The slow motion worm housings look rather later than my own and these seem to have evolved over time.

The beautifully tapered main castings are strictly to the book. Maximum stiffness where the loads are highest. Reducing in diameter where the loads are least. Russell W Porter, the brilliant designer of the 200" Hale Telescope, suggested this arrangement in his designs for the castings of telescope mountings used prior to the erection of the Hale Observatory. These (and others) were shown in the classic three volumes of "Amateur telescope Making" published by Ingalls around the middle of the last century and earlier. These books can probably still be found in major libraries and specialist bookshops. Particularly those with online search facilities. They are now rather dated but full of useful information for the creative amateur astronomer. Particularly one who likes to build and make things for themselves.

The lacquered, adjustable brass cell showing the first surface of the achromatic objective. (below) It is believed that Wildey was responsible for Fullerscope's refractor objectives. His work is legendary and, if he really was the maker, probably resulted in a very fine lens.

The massive cross sections of the MkIV mounting provide the stiffness and resistance to flexure so essential to real telescope mountings. The eye may be quite forgiving of wobbly mountings but can these cope with photography or imaging? No problem here.

An unconventional view of the instrument. Perhaps the one seen after one has just fallen off a high stepladder while trying to view something near the horizon? ;-)

What is there not to like about this classical refractor on a sturdy, well-designed mounting?

My gratitude for all the images above goes to Richard at Skylight Telescopes of London. I have enlarged his original images in Photofiltre to allow closer views. Any faults in the enlarged images are entirely my own. Richard is a specialist vendor and restorer of quality, older instruments. His website is well worth a visit for those with an interest in instruments of the last century and beyond.

www.skylightelescopes.co.uk

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Transits and eclipses

2010-04-11T06:51:00.000-07:00

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Click on any image for a larger version. Back click to return to the text.

Mercury transit. Flat batteries caught me out. The brand new, cheaper, rechargeable batteries I had just bought wouldn't hold a charge! Never trust a battery you haven't recharged at least once before the big event. Mercury is the tiny rather fuzzy speck at 8 o'clock at ~2/3 radius away from the centre of the Sun. I only managed a few images and then the camera went dead with no more batteries in the house! I think there is too much penumbra in the small sun spot rather than it being Mercury out of focus.

But Note: My computer hard drive crashed recently and lots of my images were lost. I'm wondering whether that speck isn't just a small sunspot. I shall have to dig deeper because the image date and transit date don't match by about a month. If that is mercury it isn't very sharp even by my standards.

Just to add to the confusion I recently found the image above matched the transit date of May 7 2003. High cloud obviously added to the misery of running out of batteries! The Mercury suspect is arrowed. I used Photofiltre to try and sharpen up the image a little.

Venus transit of 6 June 2004 captured with my old Sony P71 digital camera simply hand held to the eyepiece of my 6" F8 Celestron refractor. Full aperture Baader Solarfilm filter. Probably using my 15mm Meade 4000 Super Plossl eyepiece. Notice the lack of sun spots and suggestion of limb darkening. The strong pink colour suggests that this event was before I'd bought the Baader Fringe Killer minus violet filter. Which tends to whiten the pink solar image of the Solarfilm alone by adding a slight yellow tint. Not a bad result which even stands up to enlargement.

31 May 2003 at 4:20 in the morning found me standing on an ancient hill waiting for the clouds to clear. I had dragged my 90mm f:11 Vixen refractor, with video tripod and pan and tilt head up the steep and muddy path, past the standing stones from the car park far below. A couple of other people stood around waiting. A young chap had set up his SLR camera with a long telescopic lens mounted on a tripod nearby. Total silence reigned except for a distant dog barking and the odd cow in the fields below greeting the dawn. Unfortunately my view of the dawn from my garden is blocked by a low hill. So I had chosen the highest hill on Fyn to observe and record this eclipse. I could not take my usual mountings with me or I would have had a much more stable base to work from.

Eventually the sun rose out of the low clouds and I was able to take some hand held images through the 90mm Vixen refractor using the 26mm Meade 4000 eyepiece. The Sun was so dull and low that I did not need the Baader Solarfilm filter for the early shots. This one captured a sunspot. Quite pleasing considering the difficulty of holding the camera to the eyepiece with the telescope on my Bogen 3040 video tripod with pan-and-tilt head.

Local maximum obscuration with a thin veil of cloud. Well worth the effort of such an early rise.
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Home made kit:

2010-04-10T03:21:00.000-07:00

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An all brass 2" Crayford focussing mount:

I though this might amuse those with experience in working with brass. The original idea was to make a very heavy focuser for my 6" refractor. The intention was to help the balance of the telescope tube which is very nose heavy.

I threw the whole thing together entirely from brass sections found in my workshop scrap bin. This eyepiece focussing mount weighs a ton but offers smooth movement. When I first made it the focussing tube tended to roll downwards under its own weight. So I fitted a length of plastic fuel tube on the drive axle for more grip. This quickly grew flats so had to be removed. Further tightening of the spring adjusting screws eventually solved the problem once I fitted the flared brass plugs which sit in the end of the springs. These threaded plugs are self locking to the springs allowing the screws to be adjusted without slip and without removing the focussing mount from the OTA.

I copied the form of the hand-wheels from an old brass microscope using a home made radius bar with round nosed cutting tool in the lathe. The knurling wasn't a huge success and should have been straight cut rather than the diagonally crossed pattern the borrowed knurling wheels actually produced. I couldn't get remotely enough pressure to make a clean and deep imprint on the yellow brass.

The focuser has been knocking about in my unheated workshop for ages so has lost much of its original shine. The 2" Vixen rack and pinion focuser fitted to my 6" refractor has served its purpose well enough. Though I would have preferred an alignment adjustment in its supporting baseplate. Not a difficult task. Just another of those roundtoit jobs.

Here's a 5" (125mm) achromat doublet which I made many years ago. It uses BK7-F2 (crown and flint) in an approximately equi-convex crown element design. The fourth surface is slightly convex. It was used oiled and taped. I wrote my own BBC Basic ray tracing design software to optimise the colour and spherical correction. The orange stain of the Cerium oxide polishing powder is still visible on the edges of the lens. I also made mirrors from 4" up to 16" back then on various simple reciprocating grinding and polishing machines. It would have been far quicker and quite possibly better to have worked entirely by hand but I liked building and using my machines. Far more than getting slowly dizzy walking round and around a barrel or water filled oil drum.

My old spherometer has recently been upgraded with a Mitutoyo digital head bought from eBay to replace the old Imperial and Metric mechanical dial gauge heads I used back then. The lens really deserves a new cell and tube. The original tube was rolled from aircraft ply around a series of turned baffles. Beautifully light and stiff, it survived for years until the damp eventually got into the laminations. The push-pull cell was made from simple rings of plywood with aluminium rings front and back. All sawn out and smoothed with hand tools.

Here's an old snap of the 5" achromat in a 6" PVC drainage tube behind a 12" which I also made around that time. Both use Dobsonian mountings. Named after John Dobson, who popularised these mountings, they were a relatively new concept back then. They used tabs of PTFE (Teflon) riding on Formica sheet for their azimuth bearings. PVC pipe and spaced strips of PTFE were used for altitude bearings. These mountings provided incredibly stable, buttery smooth movement at very low cost compared with even the very cheapest commercial mountings.

I made the entire 12" at cost for a friend of a friend under heavy pressure to finish it. The plate glass mirror was far from perfect under the knife edge test but gave a decent view of the moon before I parted with the completed instrument. It taught me that one shouldn't waste time on plate glass mirrors in my unheated workshop. Nor try to make a living from telescope making.

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Partial solar eclipse 1/8/08

2010-04-09T04:11:00.000-07:00

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Today's partial solar eclipse started at 10.30 CET, maximum obscuration of 27% was at 11.33 and the Moon finally cleared the Sun at 12.30.

My Vixen 90M [90mm f/11] refractor was fixed to my Fullerscopes MkIII. Note the tiny counterweight needed for this small instrument.

I can't easily use the original Vixen tube rings to attach the OTA to the saddle of the MKIII mounting because of the blind screw holes. So I used inexpensive opening rings instead. A full aperture DIY Baader Solarfilm filter was pushed over the Vixen's dewshield. The filter foil is mounted and taped onto a handy-sized, plastic bottle with the neck cut off. The body of the bottle slips snugly over the dewshield with no risk of it sliding off. I was careful to remove all ragged edges from the bottle to avoid damaging the foil. The complete filter sits in a clear plastic kitchen food container when not in use to preserve it from physical damage for as long as possible. It has served me well. Transits of both Venus and Mercury and a dawn solar eclipse have been enjoyed thanks to this inexpensive yet safe solar filter. It is a revelation to use such a filter visually after decades of using eyepiece projection.

Note the use of my stable and very heavy portable workbench in the background to keep my accessories safe and to hand. I tried a tall table once but it was too unstable when I was fumbling about in the dark trying not to lose my dark adaptation. I enjoy pitch black skies in winter thanks to a complete lack of street lights within several miles. The nearest lights are hidden behind a hill and some woods.

The images below were taken through a 26mm Meade Super Plossl 4000 eyepiece using a Canon Ixus 860IS compact digital camera simply hand held to the eyepiece. A dirt cheap 1.25" star diagonal was used for comfortable viewing and easy camera pointing.

Note the whiteness of the solar image using the Baader solar foil and Fringe Killer filter combination. The lack of chromatic aberration in these images is a remarkable result for such a small outlay. Almost anybody could afford a small refractor and take very similar images to those below. There is an advantage of great stability from the Fullerscopes mounting and its massive, all-welded, stainless steel tripod. Though a steel post in the ground would probably make a better base for one of these old mountings if a clear sky is possible from a fixed point.

I missed the first few minutes of the eclipse thanks to a rusted synchronous motor and worm. Subsequently I had to guide by hand throughout. Which was a shame because the old motor had previously offered very easy guiding during previous solar observations. The protection offered to my old mounting by a tarpaulin was obviously not enough to protect the slow motions from rust. I can see stainless steel worms and a new motor on the horizon.

The first two, slightly bluish, images shown were taken without the Baader Fringe Killer filter in place. All later images used this filter and were all just under 1 Meg in size. The camera was set to auto and zoomed to its widest angle. Image quality was set to Largest and Superfine to obtain the highest possible resolution. I tried more powerful eyepieces now and then but it was too difficult to keep the Sun in the centre of the field of view without the drive running.

The sky was clear throughout except for thin high cloud and vapour trails. It was so hot in the brilliant sunshine that I repeatedly went indoors to download the latest images to avoid overheating. I hope I haven't been sunburnt. The whole affair lasted so long I was very relaxed and even managed to enjoy morning coffee and toasted rolls beside the telescope just before the maximum. There lies the advantage of being able to observe from one's own back garden. The last eclipse demanded a trek to a local hill because the Sun was so low early in the morning.

The following images were selected from approximately 150 x 1 Meg originals to show the motion of the Moon across the Sun. These have been downsized in Windows "Resizer" to "Large".

Gone! 12.30 CET and 28-9Centigrade in the shade. Too hot for me!

By fast scrolling you may be able to make a simple moving image effect. Note the complete lack of sunspots. These would have shown clearly had any been present. We are at a solar minimum at the moment.
Left click for larger images. Back click to return to the text and standard sized images.

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MkIV drives.

2010-04-08T08:33:00.000-07:00

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My own MkIV was equipped with 359 tooth 6" bronze wormwheels and geared electric motor drives without manual slow motions. Later MkIVs apparently had 7" RA wormwheels but they were never illustrated in the Fullerscopes catalogue for years after their announcement.

The Skytracker, variable frequency, MkIV drive box and control paddle were also included. The Declination drive has a reversible 240V motor. The RA drive has a non-reversible, 240V synchronous, drive motor. Which, when switched off with the control paddle, allows objects to drift across the field of view rather than offering a true reverse.

Once the RA drive is mechanically coupled to the polar axis (via the simple screwed rod clutch with attached knob) the telescope cannot be easily slewed by hand. Attempting to slew will make the worm jump noisily out of the teeth of the wormwheel. It is possible to find a middle position on the clutch which allows hand slewing with continuous electric drive but it requires some care in adjustment and careful balancing of the telescope.

(The hex head screw with locknut in the image above is to hold the new, stainless steel, polar axis shaft safely in the polar casting)

The RA drive motor with protective brass can removed.

The reversible Declination drive motor exposed.

The Declination motor drive, gearbox (without its brass protective can) and stainless steel worm driving the wormwheel:

Both motors are by Crouzet which supplied small geared motors for a whole range of timing devices. Washing machines often had a cam drum programmer with the contacts opened and closed mechanically by one or more of these little geared synchronous motors.

The motors and built-on gearboxes are enclosed in simple brass cans soldered together and a push fit onto the worm support base castings. Despite the push fit they seem to work well in protecting the motors.

NB: Later models seem to have a fine screw thread on the brass case so take great care if you are tempted to try and remove a drive motor can from a MkIV! Unscrewing would seem the safest option where any doubt exists. The motor case is made from very thin brass so use rubber gloves to get a really good grip rather than permanently disfiguring the motor can with any kind of gripping tool!

My own mounting has a stainless steel Declination worm but only a plain steel RA worm. The RA worm is very prone to rust and I would like to make (or have professionally made) a stainless steel replacement worm.

The worm brackets are held against the relevant mounting castings with a large bolt and flexible rubber washer. Small, socket head, grub screws offer adjustment of mesh between worm and wormwheel.

Here, an owner of a MkIV has sent me images of his mounting driven by stepper motors and a smart Meade "Autostar" control paddle. No doubt the overall gear ratio can be adjusted for in the device software to achieve the correct drive rate. A really smart and modern update. This MkIV looks almost as good as new.

GOTO is also available from a specialist British company called AWR Technology. There are images of their heavy duty intelligent drives fitted to a MkIV on their website. Scroll down to the middle of the page in the following link:

http://www.awrtech.co.uk/gallery.htm

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MkIV: Fixing Fullerscope's botched workmanship!

2010-04-07T03:35:00.000-07:00

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The plain steel original shafts had been a constant problem with rust forming overnight. This was unsightly and made my previous restoration work look worthless. I had gained previous experience in replacing the MkIII's shafts. So I decided to file away the paint at suitable points on the MkIV castings to find the expected cross pins or shaft fixing screws. Once exposed I simply drilled out the pins and removed the old shafts. New, larger metric screwthreads were cut in the original holes in the castings and socket head fixing screws with exposed heads were fitted to allow easy shaft removal in future.

While dismantling the mounting to fit the new shafts I noticed some serious alignment problems between the base and the polar castings. When I put a straight bar through the base casting's altitude pivot holes I discovered that the holes did not line up by a full half an inch! The same went for the threaded altitude pivot screw holes in the polar casting! The whole base assembly was badly skewed thanks to the appalling workmanship in drilling these holes. Normally this would not be noticed because the polar axis would not allow a bar to pass right through because the polar axis shaft is in the way. Can one assume that complete amateurs were allowed into the Fullerscopes workshops without skilled supervision? Who was responsible for the truly awful standard of workmanship seen in my MkIV? The holes were diagonally incorrect. Their centres needed 'moving', both along and across, relative to their castings to achieve anything remotely like true alignment.

I decided to file the holes in the castings in the direction indicated by my straight test bar. Once the holes were "moved over" to a better position with a large, coarse, round file I could drill the holes truly round to a larger size. The same work had to be applied to the polar axis casting. Larger metric threads were then cut in the new, larger holes.

The new, oversize, stainless steel, polar altitude, pivot screws look much smarter than the old rusty ones. I also fitted larger washers under the heads of the pivot screws to spread the crushing loads on the "ears" of the base casting. I also fitted very large, galvanised steel, thick, square, roofing washers as packing between the base casting ears and the polar casting. The base cast ears are actually rather thin for the heavy loads they carry. There was already sign of deformation of the flat areas where the big pivot screws had crushed the soft metal slightly. The polar altitude pivot screws now pass through the big square washers into the threaded polar casting. These packing washers were a real struggle to fit because of the concealing flanges on the casting ears. The washers had to be poked gently into place with thin strip of steel and lot of patience with the mounting lying first on one side and then on the other.

Only much later did I realise that I had denied the base casting "ears" their normal levels of friction which they applied to the polar casting. So my modifications made the polar axis sag in altitude when the OTA was removed. I just did not trust the small, altitude locking screws to hold fast in the soft castings. So I could not tighten them with full confidence that they would hold without stripping their fine metric threads. In the end I added a cheap turn-buckle and this has proved ideal. Polar angle can now be adjusted with the fingertips and stays where it is left. No more tools and no need to over-tighten the altitude pivot or locking screws. It might have been simpler to have fitted much large washers under the heads of the altitude pivot screws. Though I would not have the micro altitude adjustment offered by the turn-buckle.

By sheer luck I found an old 62mm, folded steel, car exhaust clamp amongst my junk. This is tightened onto the lower end of the polar axis casting. A fixing hole was drilled and threaded in the steel pier at a suitable point for a strong screw eye. The galvanised turn-buckle is fitted in tension between the two. I think it looks rather neat and it works perfectly for very little effort or expense. The modification cost less than £3 ($5-6 equiv.) in total and took only ten minutes to complete. Smarter stainless steel turn-buckles are available from boating shops but would probably be more difficult to adjust with just the fingertips. Click on the image below for a closer view of the turn-buckle in place.

The image above shows earlier attempts to balance the mounting with multiple OTAs and when the OTAs were removed. I simply added heavy counterweights on the over-long, polar shaft. This proved fruitless. The polar angle still moved up and down and polar axis friction increased far too much for easy pointing with only the leverage available with the short 6" refractor. Normally, when carrying the 6" F/8 refractor alone, the MkIV mounting has the just enough friction to allow easy pointing without the telescope drifting. This is still true even without the slow motion clutches being tightened.

Here is a simple aluminium alloy disk turned in my lathe to house a 1.25" bore ball bearing (shown inserted). The intention is to use countersunk screws to hold the disk onto the top of the polar casting to take the lateral loads. Hopefully with reduced friction compared with the existing bronze sleeve bearing. (which will be removed to allow more clearance) The worm housing will have to be moved upwards and a suitable clutch designed since the wormwheel itself will be moved upwards by the thickness of the light alloy disk.

The 1.25" bore, taper roller thrust bearing (sitting on top of the alloy disk) will probably be fixed at the bottom end of the polar casting in a simple housing to reduce the friction from end loads on the polar axis. I just happened to come across these bearings in a garage sale. A fortunate coincidence. A wash out with paraffin and they run as smoothly as new. Given the very low rotational speeds involved in telescope mountings there should be no bearing problems provided the bearings are well protected from the weather to avoid rust. I have since obtained some thin, flat, ball thrust bearings which are much more compact. I am still trying to work out how best to use these bearings without altering the mounting permanently.

Click on any image for a larger view. Back click to return to the blog.
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The Fullerscopes MkIII

2010-04-06T03:30:00.000-07:00

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The MkIII is/was a simple, solid, German, equatorial mounting employing 1" (25.4mm) solid steel shafts and Oilite bronze sleeve bearings. It offers silky movement and stable support for up to an 8" reflector or classic 4" F/15 refractor. It cheerfully supported my 6" F/8 refractor until I obtained the MkIV. When supporting the lighter load of my 90mm F/11 Vixen refractor it leaves nothing to be desired except (perhaps) GOTO. Any mounting which allows a digital camera to be held up to the eyepiece without camera shake is well worth having. I took lots of images this way with the MkIII on the massive welded, stainless steel tripod shown below.

The MkIII Fullerscopes mounting carrying a 90mm F:11 Vixen refractor. An easy load for such a robust mounting.

Originally the MkIII was provided with a great many different options. The cast base was available as a hollow pot with radial fixing screws to fit on a pipe or pier. Alternatively a flat base was offered to screw down to a post or home made tripod. The third base option had cast tabs to accept simple wooden legs for a tripod. The base shown above is the pot option with three thumbscrews for fixing firmly to any pipe of suitable diameter. The welded tripod shown above is almost too heavy to lift comfortably. I use a sack truck and a plank beneath two of the feet to move it around the garden. The base of the MkIII can be swivelled around a central screw and polar altitude adjustment is easy after loosening the pivot screw with a spanner.

This particular MkIII has the optional cast setting circles, synchronous drive in RA and manual slow motions. The large black plastic knobs are for secure locking of the axes by hand to allow mounting of the telescope tube or adjusting the counterweights. The motor body has suffered an injury over the years but still works well. Note the solid bronze, slow motion wormwheels.

Note: There is a high risk of shock given the usually damp conditions when observing out of doors at night in heavy dew.

With a 240Volt mains motor the mounting must be properly earthed and an RCD safety device placed at the source of the mains supply cable safely indoors.

en.wikipedia.org/wiki/Residual-current_device

Click on any image for a larger version. Back click to return to the text.

I have now replaced my original shafts with polished, stainless steel 1" bar. Due to the serious risks involved in swapping shafts I have omitted the exact details here. You either have the necessary manual and technical skills to swap shafts or you do not. Carrying out the work badly might easily lead to your death or very serious injury if a shaft should come loose unexpectedly. Particularly when observing alone after dark. The risk is just not worth it and you could permanently ruin your mounting or smash a valuable telescope!

If you absolutely must fit stainless steel shafts to your mounting then I strongly suggest you approach a professional engineering workshop to have the work done properly. The shafts are held by cross-pins or screws hidden beneath the paint. On my particular MkIII there was one hammered in pin on one shaft. With a sawn off screw in the other. Getting these out takes luck, some manual skill and reasonable tools. All the screws on these mountings are old imperial sizes which are hard to match in these times of universal metric threads. The alloy used for these castings is very soft and re-cutting metric threads to fit modern stainless steel screws is very risky. So if you do manage to swap your rusty shafts for stainless steel you may not get a strong fixing. Imagine you are up a ladder, in the dark, in a hard frost, looking through your priceless APO refractor and one of the mounting shafts just drops out onto the ground! On a cold night you could get hypothermia if you lie there unconscious for very long. If you live alone you could lie there forever in a secluded rural garden!

Even obtaining 1" Imperial round bar stock in stainless steel is not very easy these days.

Metric 25mm bar is completely useless for this task! It certainly won't fit the original castings and your slow motion wormwheels, setting circles, counterweights and fixing collars will all become too loose and dangerous! So don't even think about using metric bar. You must use 1" Imperial bar.

Warning: Getting the original shafts out of the castings could have been a serious problem thanks to the incredibly poor workmanship by the Fullerscopes workshops. The declination shaft was so loose in the badly drilled (or bored) saddle casting that they had butchered the shaft end into a tighter fit by hammering it into a mushroom! This is totally unacceptable workmanship by any standards. Had I not recognised the problem I could have cracked the saddle casting by removing the shaft by the "shortest route". Instead I had to drive the saddle carefully down the full length of the shaft using a block of wood to protect the soft casting. Believe it or not; the other shaft had been roughly knurled to get a fit in the T-shaped declination casting! It seems Fullerscopes did not even own a usable 1" drill! So you have been warned! Don't do a shaft swap unless you have the necessary skills.

The lack of skill in the machining doesn't usually show and doesn't affect the MkIII's performance, solidity or safety. Given the usually low cost of obtaining one of these Fullerscopes mountings secondhand I really wouldn't worry about it. Just don't pay a lot for one. Particularly one in poor condition or without basic slow motions. Nor in the mistaken belief that Fullerscopes is a classic antique from the great age of hand-finished brass and glass. The MkIII is a cheap, simple, solid, slightly agricultural, telescope mounting and nothing more. Charles Frank and AE mountings were far better built and finished in comparison with the simpler and probabpy cheaper Fullerscopes mountings. But these other makes probably fetch more and are usually much more difficult to find in the online astro ads or the backs of the astronomy magazines.

The dreadful Fullerscopes workmanship carries over to the MkIV which I will discuss next.

You may find the following link interesting as an insight into Fullerscopes at the "height" of their manufacturing activities:

http://www.brayebrookobservatory.org/BrayObsWebSite/HOMEPAGE/forum/So%20Called%20Telescope%20Makers.html
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The Fullerscopes MkIV.

2010-04-06T02:39:00.000-07:00

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Basic restoration of the Fullerscopes MkIV: I stared at the fuzzy images of the Fullerscopes MkIV in their catalogues for years. The catalogues never changed much but they were free until much later on when they used to send only a poorly illustrated price list to enquirers.

When the MkIV packages arrived in Denmark just before lunch I did a hasty assembly before going back to work. Having owned the MkIII for some time I was very impressed by the sheer size and weight of the MkIV as it sat on my el cheapo collapsible workbench. The 6" bronze wormwheels looked huge and the 1.25" shafts added enough gravitas to make it quite a difficult lift even without counterweights. I was delighted to finally own one despite the obvious need for a face-lift. Restoration would be half the fun even if it occasionally interrupted observing.

At this time I had yet to discover a source for black wrinkle paint so it looked like Hammerite was the best option. I stripped the layers of old paint off and as it wasn't very warm outside I pre-warmed the castings in the greenhouse prior to applying Hammerite's own special primer.

I was looking for a more modern appearance at first instead of the dowdy black gloss. The light blue Hammerite I tried first was too awful for words! So it was back to the shop for some dark blue after much discussion with the Head Gardener. I value my wife's insight in matters of taste. These are the castings painted in the dark blue, hammer finish drying in the sunshine. It seems I had also upgraded my folding workbench by this time.

The colour darkens over time and I think you will agree that it looks rather smart in an understated way. The tiny counterweights were supposed to allow my little Vixen 90mm refractor to sit on the mounting but it was total overkill and there was a little too much friction.

Here's a before and after image of the brass motor cans. I simply chucked them from the inside in the 3 Jaw chuck in my lathe and then polished with ultra fine abrasive paper then lacquered them. Quite an improvement I think.

The tarnished setting circles were also re-polished in the lathe using home made emery sticks and then silvered and lacquered using antique clock dial silvering methods.

Black wrinkle paint.

2010-04-05T04:30:00.000-07:00

*A bare MkIV belonging to an English amateur astronomer in original black wrinkle paint. The cast pot base rests in the foreground. This gave the option of a drilled flange fitting direct to the base or a pot to fit on top of a heavy wall pipe.

Wrinkle paint should not be confused with crackle paint. The latter is more typically a finish on wood. The original black wrinkle paint used on these mountings is not much used commercially these days. Though it was once used for a wide range of commercial objects. Optical instruments, radios, clocks, electrical items including humble electric room heaters were commonly coated with this baked-on finish. I have been told that the original wrinkle paint was rather toxic to those who worked with it.

Wrinkle paint can now be obtained in aerosol cans from motorcycle customisers. As it is a popular finish on custom Harley Davidsons. I was advised by my supplier that warmth is necessary to achieve a good wrinkle effect. Heat should be applied immediately after painting on a reasonably thick coat. I imagine an electric heat gun would be ideal for this "heat treatment".

As I had already used Hammerite paint on my MkIV I have never tried the wrinkle paint which I bought after a very long search. I understand some car accessory shops have wrinkle paint but I never found any at those I tried. There is still some of the original wrinkle paint remaining on the slow motions power supply box and control paddle: This looks like a lack of primer combined with years of sweaty hands.

Opinions seem to vary on the best finish for these old mountings. Some people detest Hammerite and want to see the original wrinkle finish. I am not so sure that very exposed mountings suit the wrinkle paint. In a proper observatory offering excellent protection then wrinkle paint would be the ideal choice for those seeking originality. It can look absolutely superb contrasting with highly polished and lacquered brass and bronze. I have to admit my first attempt at light blue Hammerite was a mistake. It looked horribly cheap and nasty! So I tried the dark blue and am still reasonably happy. I don't like black Hammerite so that wasn't an option. I have had to retouch the Hammerite repeatedly over the years despite careful application of the correct Hammerite primer on the aluminium castings. On the steel pier it seems to offer no better protection than primer and gloss oil paint. On perfectly clean steel rust has broken through in a number of places despite two thick coats of Hammerite four years ago. It also seems rather subject to chipping when knocked.

Here is an image I downloaded from a European amateur astronomer's website showing a MkIV in its original black wrinkle paint finish.

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Mk IV Restoration.

2010-04-04T05:02:00.000-07:00

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An early view of my MkIV mounting shortly after initial restoration. It shouldn't take long to restore these simple but robust mountings to an acceptable level of smartness and functionality. Both mountings suffer from their original choice of plain steel shafts and slow motion worms. Rust was, and still is, a problem with the mountings standing permanently out of doors with only a tarpaulin for protection. I have since replaced the axis shafts on both mountings with polished stainless steel bar. Most of the MkIV bolts and screws have also been replaced with slightly larger metric, stainless steel fixings. All the original screw threads were very tired after long decades of use and metric sizes were readily available. I also had suitable taps to cut the new threads. Unfortunately metric threads are too fine to get a good grip in such soft aluminium alloy castings. The originals screws were of a coarse threaded, Imperial type.

I welded the stand together myself from heavy steel pipe. It is far too heavy to lift but can be moved around (with great difficulty) by using a pneumatic tired sack truck using a plank spanning two of the 'feet'. The stand is then carefully tilted towards the truck and supported on my shoulder as I struggle to push it around the garden. To give some idea of scale the pillar pipe is 7" (175mm) in diameter and 5 feet tall to the massive steel flange. The heavy galvanised screwed rods rest on thick, round, concrete slabs resting on gravel sunk into the lawn to allow easy mowing.

Because there are so many trees obscuring the sky around my garden I have since modified the stand by fitting heavy duty castors (with castor locking brakes) on the rubber tired wheels. These have proved too small for use on wet or frozen lawn or my gravel drives and parking spaces. Though they would be ideal for hard paving or tarmac I have no such smooth surfaces. So it just means I have to push hard to get it all moving but it is not too difficult to reach a place where I can get a clear view of the sky. The wheels are certainly an improvement on the sack truck and plank. Ironically I have only to push the stand outside the garden to have the whole sky exposed. This however makes the passing headlights on the nearby road too bright for comfort once I have dark adapted.

Fullerscopes tried to overcome rusting problems with hard chrome plated shafts and worms but this was not always entirely successful in my own experience. Stainless steel can safely be left exposed to the weather for years without worry. Iron fittings will stain it and rust themselves fast but they can usually be freed with a block of wood and gentle taps with a hammer. Greasing the component before sliding it onto the shaft helps. A rust-stained, stainless steel shaft can be re-polished with very fine emery paper or even fine wire wool where thought desirable.

Another MkIV being spruced up with a coat of black paint. There is something about dark paint which emphasises the brightness of brass parts. Like gold jewellery set against black velvet. Or beautiful old microscopes. Here the clutch control knobs are clearly seen on both axes.

These two images were kindly provided by Richard at Skylight Telescopes. The later chapter on the 4" Fullerscopes refractor shares his images of yet another MkIV.

www.skylightelescopes.co.uk

Click on the image for a larger picture. Back click to return to the text.
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Show and tell.

2010-04-03T07:17:00.000-07:00

*My MkIV Fullerscopes mounting and 6" F:8 Celestron refractor seeing in the New Year 2004 in heavy frost. Look at the rust on those shafts! More on this later.

Click on any image for a larger view. Back click to return to the text.

I had a couple of Fullerscopes websites from a few years ago which became inaccessible for updating due to two changes of ISP. Agent Orange has now deleted them. I'd like to thanks those who have emailed me with images, ideas and questions regarding their own Fullerscopes mountings after visiting my old Freeserve websites. I thought I'd start a blog on my Fullerscopes mountings to share my progress in restoring and modifying them. The blog format offers great flexibility in updating and a wonderful freedom to post lots of (enlargeable) images completely free of charge.

Why should I bother with two websites and a blog about these 30-40 year-old mountings? Simply because I find they offer a rock solid, reliable, stable telescope support at relatively low cost compared with most of the mountings available today. The modern approach seems to be deliberate complexity and light weight. Usually at the expense of something which shimmers for long seconds every time the telescope is touched or the breeze blows. With axes clamped and drives engaged I can literally thump the telescope tube with my fist and continue viewing without interruption. More importantly for me I can just hold a digital camera up to the eyepiece and take quite decent astronomical "snaps" without visible camera shake. This is lasting value of the solid gold variety but at remarkably low cost compared with many new mountings.

An image of a modern HEQ5 mounting kindly sent to me by an English amateur astronomer. Note the comparison in casting cross sections with the Fullerscopes mountings. What about the skinny legs of the tripod and the even skinnier axis shafts? Then there's the considerable overhang of the Declination casting before it meets the saddle. Where the very short wedge is supposed to carry the entire weight of the OTA and any off axis loads placed on it by the observer or the wind. (OTA=Optical Tube Assembly or more simply: telescope tube) Note the tiny setting circles and the tiny wormwheels hidden away within the tiny main castings. The Meade LXD55 looks very similar in appearance. Ask yourself why it was built this way.

Now look at the solid shafts and castings of the MkIV. Designed to carry the loads properly distributed by the use of carefully shaped conical castings. The tube cradle is 24" (60cm) long and has a massive collar fixed directly to the declination shaft with reinforcing webs running the entire length of the casting. The mounting base is bolted down to a flange supported by a heavy 7" diameter pipe pier carrying the loads and any vibration directly down and into the ground. There are no obvious weaknesses or bottlenecks anywhere in the design. All the loads of the OTA are carried through stiff casting cross sections and heavy shafts. The axes are further reinforced by duplicated 6" diameter flat bearing surfaces to further avoid flexure. The largest cross sections are at high stress points while weight and material has been sensibly saved at lower stress points. The 6" wormwheels literally dwarf those seen in most modern Chinese mountings. Compare the cross sections of the castings.

Which of these two mountings was designed by an engineer with experience in amateur astronomy? Why was so much forgotten about stability in the intervening decades? The MkIV castings themselves actually weigh very little without the heavy shafts. The MkIV mounting could be easily modernised. Possibly by using much larger diameter stepped tubular axes with opposed conical roller thrust bearings (or angular contact ball bearings) for lower friction with considerable weight reduction. (if it was really thought desirable to lighten the mounting to make it more portable) An aluminium pier of similar construction to my welded steel one would save a lot of weight if the equipment had to be stored indoors and only brought out for observing. Lockable wheels and hard surfaces would make any weight reduction superfluous if the pier and mounting were safely housed in a garage. Or the pier pipe cast into a concrete block in the ground with the mounting permanently set up and protected by a secure, waterproof cover. Thereby allowing the amateur astronomer to attach the OTA at a few moments notice and begin observing.

Here's a typical wide-field, hand-held shot of the Moon taken through my 6" F:8 refractor. The digital camera was simply held to the rubber eyepiece shield and the object centred in the camera screen. The camera used here was an old Sony P71 with a tiny screen. The image is still quite pleasing to my eyes. It has simply been downsized in Windows to "Large" from a half meg original size. No other processing was involved. The slight colour on the lunar limb is due to a lack of minus violet filter. From memory the eyepiece used was a dirt cheap 20mm no-name eyepiece. I normally use a cheap no-name 1.25" star diagonal to avoid neck wringing just to be able to see the camera screen. From long experience with this star diagonal I cannot see any difference in image quality compared with not using one at all. I have repeatedly observed the planets and the Moon "straight through". Then fitted the diagonal. I simply cannot see any difference in detail. Perhaps I was just lucky to get a good one. The reason for owning these cheap things was not abject poverty. Just that the distant vendor/wholesaler I visited could not accept credit cards. So my purchases were limited to the cash I had in my wallet!

Here's a typical image example showing the solidity of these old Fullerscopes mountings. The Moon captured with a hand held digital camera simply pointed through a no-name, 10mm Plossl eyepiece fitted into a no-name star diagonal in the focussing mount of a secondhand Chinese 6" F:8 refractor on a 40 year-old MkIV mounting. Not even a minus violet filter was used here as can be seen by the slight overall wash of violet in the shadows. (if you left click for enlargement)

I hadn't even managed to centre the image in the camera so there was also some assymetric vignetting. So I had to crop the image a bit to hide my clumsiness. This is just the price one pays for owning a digital camera with a tiny 1" focussing screen at that time. Close inspection suggests many tiny craters lost in the "grain". How I wish I had set the camera to a higher resolution back in those days. It was just that the Sony took so long to reset after taking a high resolution image that I became very impatient standing there in the cold at the telescope.

This image, for all its faults, speaks volumes for the quality of these rather fast [F:8] Chinese 6" refractors. With more care in optical alignment and better accessories and filters this telescope could be pushed to achieve far better lunar images. Fixing my latest Canon compact digital camera at the eyepiece would no doubt work wonders in improving image quality. I just wanted to show what was possible 5 years ago using low tech on a tight budget without getting involved in webcams, laptops and image stacking software. Or multi-thousand pound/dollar/Euro apochromatic refractors and GOTO mountings for that matter.

If you can afford over £10k for a telescope mounting then surely you don't need to keep moving it? So why make it ultralightweight if it will never move from its observatory or garden pier? Perhaps you are one of those people who like to go to star parties? Fair enough, but most of us observe from our back gardens or yards. Perhaps you can't afford an observatory so set up from scratch each time? This would require considerable enthusiasm for the hobby of telescope equipment assembly rather than observational astronomy. Just waiting for the instrument to cool down would put me off observing in no time at all. Far better to store the mounting outside on an immovable pier and bring the OTA out from unheated accommodation. A couple of minutes from making the decision to go outside I have fitted the OTA into the rings (or wedge) and I am observing or taking pictures. Can you say the same for your own set-up?

Here's a comparison between the MkIII Fullerscopes in the foreground against the much larger MkIV.

I purchased the MkIII mounting first from a gentleman in England. Later I bought a MkIV online from an astronomical society also from England. The MkIV had once carried a large reflector but had been retired and placed in storage. The price I offered and which was accepted was quite modest despite the problems of getting the heavy mounting to me in several large and heavy parcels. I let them keep the counterweights as I could easily make my own to match my own lesser balancing needs. I was delighted to discover that this particular MkIV had variable speed electric motor drives to both axes with control box and paddle. The engraved slip-ring setting circle mounted directly on the RA slow motion worm wheel was a nice feature. The Declination circle is fixed on the rim on an alloy casting. Obtaining originals of these items secondhand would have been a impossible given the considerable age of most of these old Fullerscopes mountings.

All of my 5-year-old Freeview websites have now been deleted by Orange. Those old websites were put together just after obtaining my very own Fullerscopes mountings. I had dreamed of owning one of these mountings since I obtained the first Fullerscopes catalogue back in the late 60s. Despite the hours spent poring over the illustrations and descriptions there was no way I could reasonably afford one back then. I have always had far too many other hobbies so there always seemed to be too many other more pressing demands on my income. I had instead built many different mountings and telescopes (and their optics) over the years. I never did own any astronomical equipment from Fullerscopes. So the original dream had taken all of 35 years to become reality. Obviously I can't have been too disappointed or I would not be writing this blog. If nothing else I have re-discovered the importance of stability and ease of use. Some of my own mountings were anything but user friendly.

Commercial refractors have now replaced my own DIY optics and OTAs. I find them easier to use and rather more likely to be used thanks to their reasonable size and ease of setting up. Anything which stops me sitting at my computer has to be worth making the effort to go out in the freezing cold! I find my refractors light enough to handle and very easy to put away without having to worry about dewing and optical deterioration. I simply leave an eyepiece in the focussing mount and leave the telescopes standing on their noses in secure but unheated accommodation. The OTAs are often put away plastered in ice or heavy dew. Fortunately refractor dewshields are usually large enough in diameter and tough enough to offer plenty of stability provided one doesn't own a cat, a dog or a toddler with access to the telescope storage area. Cat's have a habit of rubbing themselves against anything they pass. I wouldn't trust a free-standing refractor to remain upright after a brush with our feline friends. I suppose suitably-sized, hinged tube rings could be screwed to the wall to support the top end of refractor OTAs in complete safety. An eyepiece should always be left in the focussing mount to stop dirt and dropped objects from gloing straight through the open draw tube.

A slight downside of nose-down storage of refractors is that the back of the lens may accumulate dust and condensation over time. Focussing mounts are rarely perfectly sealed. Usually the objective cell is screwed onto the main tube though it often takes some considerable effort to separate the cell and tube. Don't use gripping tools or you'll ruin the finish or damage the telescope.

It is not recommended that one remove the glass objective itself unless one has considerable experience and the knowledge to do it properly. It is all to easy to get the glass slightly twisted in the cell. Then to break large chunks out of the vital, precision optical surfaces in the struggle to remove the glass. Far better to use soft tissues to gently clean the exposed lens surfaces as the glass sits safely in its cell.
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