I seem to be in a finder scope mode at the moment. Here is my build of a 60mm RACI finder /spotting scope, using
U.S.S.R. built 60mm f/4.5 achromat lens (which I'm taking to be a cemented doublet lens).
Back in the 1980s, I obtained around eight of these lenses. All but two pieces have now been sold, but I'm keeping my last
pair until death. The lenses were made at Zagorsk optical and mechanical plant (ZOMZ) where they were used for the
20 x 60mm binocular and monocular that the plant manufactured. These really are a superb piece of glass, from their striking
purple lens coatings that still mesmerize the eye after 36 years, while the views are so sharp you could shave wth them.
Over the last couple of decades a story has developed that Zomz made some samples of the binocular purely for the
U.S.S.R. market and that they had better glass than the ones exported to the west. The story might have come about
by a tenuous link to the optical company Lomo. When I purchased my samples, two of them came with protective hard lens
coverings onto which was written the name Lomo. On the covering there was also the Lomo name and logo in embossed relief.
I tested this two lenses along with my other samples and could not see one jot of difference between them. All of them were
truly superb little achromat lenses. What was going on at the time is anybodys guess, and after nearly 40 years will we ever know?
Mybe someone out there got a set of optics with the Lomo logo on, and a story developed from that.
Or mybe someone got a pair that had better than average built eyepieces, who knows. For me the eyepieces also seemed the
poor relation in the optical path.
Onto the build. The tube is made from PVC drain pipe and a straight in-line drain pipe connector. To make a lens cell, I had to
machine some of the internal surface from the pipe, this then allowed the pipe to be pushed onto the metal lens cell.
The focus tube is made from a metal tube which slides in internal rings machined from 6mm plastic. On the side of the main tube
is a set screw which stops the tube from moving after focus is obtained. All parts are simply push fit. I even machined a 50mm
aperture mask, as I would like to do some side by side testing with some 50mm finder scopes at some point.
In use, this lens gives really, really good views. As a finder I get 5.5 degrees. The lens takes magnification well. Observing the
moon at 108x, there is a very slight pencil thin line of deep purple on the limb of the moon.
The scope is easy to hold in one hand (even for quite long periods of time), yet it has a very solid feel about it even though it's
made from PVC pipe. These little lenses really are a very nice piece of glass.
Here are some photos.