Rubinar's MC 500mm f/5.6 — a compact Soviet M42 catadioptric mirror telephoto.
The MC Rubinar 500mm f/5.6 is a Soviet, later Russian, catadioptric mirror telephoto lens made in M42 and other mounts. Using a mirror-lens design based on Maksutov principles, it packed a 500mm focal length into a short, compact barrel, offering long reach at a fraction of the size of a refractive telephoto.
This is a manual-focus M42 screw-mount catadioptric lens with a 500mm focal length and a fixed effective aperture of f/5.6. As a mirror lens it has no adjustable diaphragm, exposure being controlled by shutter and ISO or filters. Focus is by hand. It is a short, stout lens for its reach. Exact weight and element figures are not asserted here beyond the verified focal length and aperture.
At 500mm the lens reaches distant wildlife, sport and landscape details in a remarkably compact form. Mirror lenses render out-of-focus highlights as characteristic rings or doughnuts owing to the central obstruction, a distinctive look. The fixed aperture and manual focus suit deliberate long-lens work, ideally on a tripod for sharp results.
Used copies are affordable relative to refractive 500mm lenses and valued for their portability. Inspect the mirror optics and front glass for haze, fungus and coating issues, confirm the focus is smooth, and check the mount and any tripod fitting. There is no aperture to test. An M42 adapter allows compact long-lens use on mirrorless with a support.