Part 1: A 12" Fullerscopes Newtonian-Cassegrain reflector.

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My contact in the UK has been in correspondence with a gentleman in Australia who has been restoring a large Fullerscopes reflector. The pride of the Fullerscopes catalogue: A 12" Newtonian-Cassegrain on a driven MkIV mounting. The combination provided a convertible instrument. One which could provide high powers for planetary work via the Cassegrain optics. Or, with a change from a small convex secondary mirror to a flat diagonal: Provide the wider views normally associated with the Newtonian.

It must be remembered that the Fullerscopes era was prior to such large instruments becoming almost commonplace. A 12" was considered a large instrument when this one was manufactured.

The instrument is housed in a very attractive, rotating fibreglass dome. The protective enclosure may simply be a secure resting place prior to installation. Its present situation would seem to limit the view of the sky to high altitudes.

The view inside the dome proves how large the protective enclosure must be in practice. The following images are pror to restoration.

The sheer scale of the instrument is obvious from the way it makes the already-large, MkIV mounting seem small. Mounted on top of the OTA is a 3" classical refractor. The adjustable guide rings allow the smaller instrument to be used as a guide telescope for photography. It can be moved, relative to the main telescope, to point on any nearby star or object. The main instrument field of view would not be available during photography due to the film cameras used at this time. A very long focus guide telescope would allow high magnifications with low power eyepieces. The photographer could use the star in the field of view to make small corrections to the drives. Allowing the main instrument and its camera to remain fixed precisely on the object being photographed.

The view of the instrument from the other side. The smaller, finder (telescope) is of ample proportions in itself. A small finder on such a large instrument is pointless. It would mean that objects in the field of view of the finder would be so much dimmer than the main instrument. It would thus be difficult to home in on dimmer objects which are easily within the grasp of the 12". 

A closer view of the MkIV showing the AWR drive motors. These are a later addition. They provide not only greater power over the original synchronous motors but tighter control of the instrument's movements. Slewing may even be possible. A feature which eludes the slow change of speed of the original motors. The Fullerscopes paddle and VFO control unit only allowed very modest changes to the sidereal drive speed.

Another view of the telescope on its mounting. Note the poor condition of the original black paintwork. It has faded to a dull grey in the time it has been housed in the observatory. Perhaps UV light can penetrate the dome despite the white paint applied over the translucent GRP dome.  

The white paint seems to have held up better than the black over the decades. The original black paint would presumably have been Fullerscopes hallmark, black wrinkle paint. Its texture added a hint of luxury to their instruments. Though Fullerscopes did not use it exclusively. Charles Frank used black wrinkle paint as well and may well have inspired Fuller to use it in turn.

The large and heavy instrument is counterbalanced by a number of weights. Showing exactly how heavy the instrument really is. Having the finder and guide telescope beyond the main tube only adds to the counterweights needed to balance the instrument.

The telescope's main tube is fitted with a so-called "slip ring". This would allow the entire instrument to be rotated in the massive, felt-lined mounting rings. The slip ring merely stopped the tube from sliding straight through the mounting rings.

I am most grateful to the gentleman in Australia for these fine images. Also to my contact in the UK for taking the time and trouble to forward the images and technical details. My thanks go to both.

This concludes the images and description of the instrument "as found" in its dome. In the interests of keeping my blog posts user friendly I shall end here and begin another post on the restoration. A large number of images can take a while to download on a slower internet connection. To avoid such users losing patience I shall break this project into several posts. The problem with doing so is that later posts appear first. Showing the finished restoration before you will see the posts with the instrument in its original state. 

Click on any image for an enlargement.

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