The Industar-50 was a screw-mount lens for 35mm rangefinder cameras. The lenses were made since 1959 by KMZ, mainly as M39 39mm screw-mount standard lens for the Zorki camera series. Older variants (ancient Leica lens style) were made by LZOS. An M42 variant Industar-50-2 for SLRs was available. This variant is popular for use as "pan-cake" lens on modern SLR bodies by means of an M42 screw-mount adapter.
The Industar-50 was a 50mm f3.5 lens, derived from Zeiss's Tessar 4-element lens. It was nicknamed the "Eagle's eye". Its brand name Industar was used for all similar 4-element/3-group lens constructions of the whole soviet photo-optical industry.