Cheap Astronomy – Blast From The Eighties: 60 / 900 Refractor With EQ-2 Mount

I could not resist it, I had to buy another cheap scope… :-) The scope was incomplete, and I bought it mainly for the EQ-2 mount – but it might turn out to be a nice entry level scope.

Some data:

• Bresser Art. Nr. 45-1200 
• Labelled "Circle T" (which means it came from the Japanese Towa company)
• No indication in which country it was actually manufactured (Japan? Taiwan? China?)
• Achromatic doublet refractor (commonly referred to as "Fraunhofer-type")
• The nominal aperture is 60mm
• The nominal focal length is 900mm
• This comes out to a long focal ratio of f/15
• Silver OTA
• The eyepiece size is 0.965 inch
• Came with an EQ-2 mount
• 6x30 finderscope with cross-hairs
• Focuser has "dual action": Rack-and-pinion and "pirate scope" sliding drawtube
• Almost everything is made from metal

The scope seems to be very similar to what has been (during the same time) sold under the Tasco Meade brandname in the USA. As far as I can see it is very similar to the Meade model 291 refractor. As far as I can see the 291 were made by Towa as well, though I could be mistaken. The silver series was supposedly the "slightly better" one from Bresser back then.

The scope came with the OTA, an EQ-2 mount without tripod legs, one prism diagonal, one "Porro" erecting prism for terrestrial use, a 6x30 finderscope with bracket and all of the little screws and most of the caps (plus the packaging from a similar "Apollo" telescope). What was not included were eyepieces, nor were there any tripod-legs, the eyepiece tray or light for the tray (but the tripod legs from my EQ-1 fitted somewhat, so I borrowed them). Missing as well was the counterweight-rod and control cables for the EQ-2 mount (again, borrowed from my EQ-1), as well as one nut for closing the OTA-bracket.

Both the scope and the mount seemed like they have been seldom (if ever) used, though there was some wear on the finderscope and the prism diagonal. There is even still the protective foil on a scale of the mount and on the knobs of the focuser!

Granted, the aperture is small, but the focal length is long, so I should be able to try higher magnifications for planetary viewing on Saturn or Jupiter with my still limited selection of eyepieces.

And of course, when one buys a scope, the weather turns bad. So I made only some preliminary tests. The chromatic aberration seems very small, as should be expected from a f/15 focal ratio. During the daytime I could increase the magnification so far (with my cheap 3x Barlow) that I started to see dust on my Ortho10mm, and started to see some floaters and other crud in my eyes with my H6mm.

Some of the things I noticed:

• OTA outer diameter is 63mm
• The counterweight-rod for EQ-2 mount has probably an UNC 1/2"-13 thread, (unlike the M12 thread on my EQ-1)
• The counterweight-bar of the EQ-2 rotates with the scope (unlike the EQ-1)
• The tension of the "pirate scope" focuser is maintained by cardboard – obviously this cardboard has deteriorated over the years, and the focuser has lost tension. So I needed to take the focuser apart, put one carefully placed piece of electrical tape on the cardboard (not on the circumflex, but along the length of the cardboard) and reassemble it all. Now it is a bit too firm, but that is OK.
  [Update] I had to completely remove the cardboard from the drawtube, it was getting loose again and adding tape made it worse. I put three strips of "textile" tape in there, padded it with several layers of electric tape and topped it of with thin "aluminium tape" – now it seems good. And what's more, it is easy to add tension by adding layers of aluminium tape. [/Update]
• Little pieces of the cardboard (from inside the focuser) had found its way on the rear surface of the lens. And there were some defects in coating of the rear surface, probably caused by the rotting cardboard pieces. But after removing the dirt, the damage seems benign.    
• The finderscope seems OK.
• The finderscope's bracket is of "single ring" type, with three set-screws – and adjusting it is impossible without modification, as the end (opposite of the set-screws) is too wide for the finderscope. After I put a layer of electrical tape around the finderscope (opposite the set-screws) I could adjust the finderscope reasonably well (and when tightened down all screws a bit, the finderscope seems to stay in alignment – everything is metal, after all).
• The 60/900 is much lighter than my 76/700 Newton – the one counterweight I have (which is just about enough for the Newton) is too much for the 60/900!
• The OTA and focuser seem to be properly baffled. The baffles inside the focuser's drawtube are small, however both a rough estimate and a visual inspection confirm that the baffles are very well placed. (Only minor point is that both baffles inside the drawtube are not painted black, but instead have their "natural" metal brass?/galvanized? finish)
• [Update] The focuser had some shifting, and I when I dismantled it to remove the cardboard, I removed the single piece of textile tape that was put there in the focuser – focuser shifting is awful at an telescope and most of the time it would be completely avoidable during production with some simple measures. But one can make a simple DIY solution: Instead of the single piece of tape, I put two "rails" from flocking material in the focuser (as I did in the 70/300). That greatly reduced focuser shifting, but there is still some. I will have to improve the "rails" at least once more, but I'm confident that I can remove the shifting almost completed within two iterations. [/Update]

I'm going to play around with a bit, and ask a friend to make me make myself some simple wooden tripod-legs for it. And then I need to get another counterweight rod and something as counterweight.

It seems like a nice scope.

[Update 2013-08-14]
Today I tried solar projection using an Carl Zeiss Jena microscope-eyepiece (Huygens 35.7mm) and I must say this scope (with its small aperture, long focal ratio and metal baffles) is well suited for observation of sunspots. As long as we still have observable sunspots, that is.

An image made today (14th August 2013) by the SDO solar space observatory captured in the 4500Å continuum. The image shows the two medium sized sunspot groups (or rather several groups), which I could spot as well with my 60mm/900mm refractor by using eyepiece projection.