The 3M-5SA 500 mm f/ 8.0 (Russian: "3М-5СА") is a mirror lens with an apochromatic multicoating. It features a constant aperture.
The lens is equipped with a mount for interchangeable Type A adapter rings (KP-A/N, KP-A/M42, etc.). It was supplied with M42 and M39 bayonet mounts.
It came in two modifications:
- 3M-5A from1976 to 1987
-3M-5SA from 1983 to 1991.
The SA variant differs from the former in smaller size and weight. It is not equipped with a built-in hood and a tripod socket, either. The lens came complete with a set of 72 mm filters: N-4х, O-2.8х, ZhZ-2х, UF-1х.
The A variant features different parameters: filter diameter - 77 (!) mm, diameter - 94 mm, weight - 1225 gm. It is equipped with a telescopic hood and two 1/4" and 3/8" tripod sockets. The lens came complete with a set of 77 mm filters: NS-8, OS-12, ZhZS-9, ZhS-0.
Angle of view - 5° Resolution: 40 lpmm at the center, 20 lpmm at the edges Coefficient of transparency - 0.7 Scattering coefficient - 0.03
Retail price of both lenses - 200 Soviet rubles (1985)
The 3М-5SA 500 mm f/ 8.0 is one of the lightest, most convenient and compact 500 mm lenses.
Roman Napreyev remarks: "I was very surprised to find out that the 3М-5SA was not equipped with a tripod socket.
When I purchased the lens, I was so happy and didn't pay attention to that. Besides, the rest of its merits were present. So, no sooner had I mounted the Tourist-FL ocular attachment to test its visual performance than I found out that the lens had no socket. In fact, I had bought this lens to observe the eclipse. Astronomical observations are the first thing that occurs to you when you deal with a focal distance like that, but the absence of tripod ... The lens produced shaky images even when lying still on a balcony railing. To make it suitable for astronomical observations it was necessary to invent and make a dedicated tripod socket collar.
Nevertheless, its optical performance was equal to that of a good telescope with the same parameters. For example, it covered more details than did my modern German 60 mm apochromatic telescope of very high quality which was much better than any Tourist telescope produced at the LZOS. (They both featured a 50x magnification.) In addition, even the apochromatic lens did not manage to produce so crystal-clear image free of any chromatic aberrations as did the mirror optical scheme designed by Maksutov..."
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Posted by: Sergei Borodin Date of publication: 02.08.2010
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