MTO's 1000 1000mm f/10 — a classic compact Soviet M42 catadioptric mirror super-telephoto.
The MTO-1000 1000mm f/10 is a Soviet catadioptric mirror telephoto lens made in M42 and other mounts. A well-known Soviet super-telephoto, it used a Maksutov-type mirror design to fit a 1000mm focal length into a barrel far shorter than any refractive equivalent, for very distant subjects at modest cost.
This is a manual-focus M42 screw-mount catadioptric lens with a 1000mm focal length and a fixed effective aperture of f/10. As a mirror lens it has no adjustable diaphragm, so exposure is set by shutter, ISO or filters, and focus is by hand. It is a stout lens for such reach. Exact weight and element figures are not asserted here beyond the verified focal length and aperture.
At 1000mm the lens reaches extremely distant wildlife, the moon and far landscape detail in a comparatively compact form. The central mirror obstruction produces the ring-shaped out-of-focus highlights typical of catadioptric lenses. The very long focal length and fixed aperture require a sturdy tripod and careful technique for sharp results.
Used copies are affordable relative to refractive super-telephotos and valued for their portability at this reach. Inspect the mirror optics and front glass for haze, fungus and coating issues, confirm smooth focus, and check the mount and the essential tripod fitting. There is no aperture to test. An M42 adapter allows use on mirrorless with a solid support.