25.08.2025 Reality beckons. Optics for sale.

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  Monday 25th.

  My lifetime passion for telescope making is finally at an end. 

 I have demolished my entirely self-built, 2 storey observatory. The loss of a permanent mounting means lifting heavy OTAs is equally at an end. My sturdy, DIY dome supported several pulley systems. To aid lifting my telescopes into place above head height. 

 I am 78 and don't seem to be getting any younger. At least not according to the bathroom mirror. Which I believe is perfectly normal. The mirror, not the old man reflected there. 

 I have some interesting optics. Which might well interest others. The problem is where to advertise them. 

 Stargazer's Lounge has a European small ads forum. With only a small number of ads. Compared to the huge number of ads in the UK section. Does anybody read the European list? Who knows?

 I am banned from Cloudy Nights due to the mention of modified and self-built, solar telescopes. 

 Denmark has a tiny population and therefore far fewer amateur astronomers than the UK. A small ad in one of the general, online, small ads websites under "telescopes" is unlikely to be seen by many potential buyers. 

 Facebook has online ads but who knows the geographical coverage? The largest market is the US. With some parcel services currently suspended due to Chump tariffs. There is also the problem of import taxes. Which can make purchase limited to those seeking a particular item which exactly matches their needs. Currency exchange, heavy postal charges and ensuring payment is also an issue.

 Listing my items here is unlikely to reach many amateur telescope makers. International postage of large telescope tubes is impossible or hideously expensive. So only the objectives [an focusers] can be sent. Which further limits interest in buying for some amateur astronomers. 

 Few have access to the tools or the necessary skill to build a complete OTA from scratch. Though it is remarkably easy if you have access to the straight seamed, thin steel ducting I use. Not the ugly spiral seamed tube. The straight seamed ducting is intended for dust extraction in furniture factories. Where fire is a serious, potential risk. Being galvanized and intended to be exposed for decades. It is attractive and an ideal material IMO. At 0.3mm thickness it is certainly no heavier than aluminium tube. Which must be thick enough not to bend under its own weight. I never saw any rust on the tubes I selected from the vast heap outside the local furniture factory. Usually for the small price of a contribution to Friday cake day.   

 Some of the items I want to part with include:

 A signed 10" f8 [250mm] Lockwood parabolic [planetary] mirror 1/30th wave in original packaging. Lockwood's optics are very well known and respected in US astronomy circles. Though he is usually too busy to make smaller mirrors these days. I was able to effortlessly view several small craterlets in Plato on the Moon. Sadly I was never able to build an OTA of low enough weight to match my decreasing strength.  

 Such an OTA could be mounted as a Dobsonian Alt-azimuth on rollers for concrete. Or a stable trolley with wheelbarrow wheels? My sky is far too blocked by trees now. To use one in my own garden. I'd have to travel at least 120m just to escape the absent neighbour's hedge.    

 An iStar 7" F12 R35 [180mm] refractor objective in its collimatable cell. I mounted this in an 8" diameter steel [ducting] tube with a 3.5" Starlight Feather Touch focuser with slow motion.   

 I also built a folded version. Using two, superb quality optical flats of 3"&4" imported from the USA. All of this can be read about and is heavily illustrated in the earlier posts here on my blog. From around 2015. Where did the time go?

  An iStar 6" f/10 [150mm] H-alpha corrected refractor objective in its collimatable cell. I also have a matching Baader 160mm D-ERF full aperture Solar blocking filter. Mounted in a Telescope Express aluminium cell. It has [had?] a 2.5" Feather Touch focuser with slow motion of course. The Starlight Instruments focusers are superb and well worth the price over mere pretenders. 

 This makes a large aperture, solar refractor for high resolution imaging. But only with the necessary etalon and blocking filter. Or a Quark? You'd have to buy your own filters. Or dismantle a smaller H-alpha telescope. To obtain these vital parts. I posted lots of successful H-alpha images on various Astro Forums and here on my blog. Both objectives can be used for white light, lunar and planetary imaging of course.

 Do not fool yourself that any of these optics can be mounted on a flimsy equatorial on a lightweight tripod. The resulting telescopes need very adequate support. I doubt my home made, massive equatorial mounting holds any interest. Except for those with the skill and tools to complete it to their own standards. Even my heavily reinforced [Beacon Hill] worm housings simply flexed too much for accurate GoTos. Though it tracked very nicely for many hours once it was centered on the sun or Moon. And often did! 

 

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8.08.2025 Lunt LS60MT repaired! 😊

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   My Lunt 60MT has been returned by Bresser. The Lunt distributors for Europe. They had replaced the blue and the UV/IR filters free of charge under guarantee.

 The telescope is back to normal and tunes in H-alpha near the start of the thread. It was rather cloudy at first but thinned. Enough to be able to make out lots of nicely sharp proms and surface detail. I tried a variety of Meade 4000 Plossls. Ending up with the 9.7mm for ~43x. 

 I cannot honestly confirm whether the telescope is better or worse performing than before. I so rarely used it visually. The etalon and BF were mostly used for imaging in the 6" f/10 and that was over three years ago. 

 I completely lost interest in everything after my wife died. Only now am I rebuilding my enthusiasm for solar. To the tune of ordering a cheap zoom eyepiece. An Omegon Magnum 8-24mm and a Lunt Sol Searcher sight. I don't currently own any equatorial mounts. My huge and heavy DIY equatorial has been dismantled. 

 I tried my TE binoviewers in the 60MT but was unable to reach focus. With the 1.25" TE star diagonal in place there wasn't sufficient inward focus. I tried with a Shorty 2x Barlow and a 2.6x GPC but no. The problem is the star diagonal. It adds too much to the light path. The sun was far too high to use the telescope without the star diagonal. 

 I already owned a straight through, Lunt B1200S2 blocking filter. So did not order a Lunt Solar BF diagonal containing a blocking filter. When I ordered the 60MT telescope. For its much bigger etalon than the Coronado PST. Which I had been using previously for high resolution imaging. 

 I understand from users online. That binoviewers can reach focus with the BF diagonals and a Barlow or GPC. Though there are binoviewers with 1x power and zero light path. Which have received rather mixed reviews. They are also quite expensive. Making the potential purchase a costly exercise in folly if they should not suit me. 

 Besides, I prefer much closer views than the LS60MT can manage alone. The problem is finding a mounting which could cope with my long and heavy 6" f/10 H-alpha refractor. I need to be highly portable to be able to see the sun for most of the day. Due to all the trees and hedges around my home. Which probably means a strain-wave mounting. Which may not be able to easily manage my 6". Whatever the manufacturer's load capacity claims. 

 The mounting has to be properly supported. Depending on the telescope load applied. Its length, weight and accessories. Which means a tripod has to be carried as well. The lightest carbon fiber tripod might not be ideal. Now, as I approach 80 I have to consider the risks of dropping very expensive equipment. It is no longer a matter of climbing up to my second storey observatory and simply opening the shutters. 

 I could use a smaller, shorter refractor. Say a 100mm f/7 to better suit the 60MT etalon. The 6" iStar objective, with its expensive, front mounted D-ERF, would have to be sold. To help to finance a much more portable set-up.

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6.08.2025 Near 100% cloud cover.

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  Wednesday the 6th Bresser has returned my Lunt 60MT solar telescope form their repair department. With the blue and UV/IR filters replaced free of charge under guarantee. 

 I quickly dragged my Manfrotto CF tripod outside and mounted the telescope. There were a few blue patches between the clouds and some of them crossed the sun. Often briefly, as Storm Floris moves ever away.

 I was able to sharply focus several group of sunspots but no sign of any other details. I unscrewed the pressure tuning knob completely to zero to atmospheric air pressure. Then began to screw it gently back in. 

 Just as I reached the fully inwards position I was rewarded with sharply defined prominences. Though still no surface detail on the sun. This coincided with 100% cloud cover! So it all had to come back indoors again. 

 It occurs to me that the tuning pressure could be increased with a taller piston. Which means the same thing as adding something to displace air volume above the piston inside the brass cylinder. This would achieve tuning with the tuning knob further out for exactly the same pressure. 

 Which might be useful where the knob must be screwed fully in to tune to H-alpha. Whatever I use to boost the piston volume should have a central hole. To allow the compressed air to freely enter the etalon housing. There is no need for the packing piece to be fixed. Because it cannot escape. 

 Though it must be made to match the cylinder bore with some clearance. If it were much smaller it might jam between the piston and cylinder face. Before the necessary compression is achieved. It must be made of some reasonably dense material. Like metal or plastic. To avoid it simply absorbing air as it is compressed in the cylinder. So foam, for example, would be a poor choice.

 There were fleeting moments of sunshine in the afternoon. I tried again and was able to tune with the knob well unscrewed. Unfortunately the sun was never truly clear of cloud. So I was denied a sharp view in H-alpha. Though it did look promising. With lighter areas clearly defined in better moments. I tried taking a few snaps with my phone but the sun was completely overexposed. 

 

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