Industar-50 was a very successful Soviet made lens. It was a standard or optional lens on practically every Zorki camera, from Zorki-S in the mid 50's to Zorki-4K in the mid 70's. The lens was also made in a 39 and 42 mm SLR mount and was installed (standard or option) on every Zenit model as well, from Zenit-S to Zenit-E. It came in different shapes and finishes, from a chrome collapsible Elmar-style lens to a black "flat" Zenit lens. The optical formula was always the same, the lens produced sharp and contasty images.
This Industar-50 is the newer, rigid barrel design used on the Zorki-4, Zorki-5, Zorki-6 and Mir.
The lens was made in 1959 by KMZ plant.
* Focal length: 50 mm, coated glass, chrome finish.
* Maximum aperture - 1:3.5 (settings from 3.5 to 16).
* The lens couples with a RF of any threadmount Leica or Leica copy.
(Source: www.fedka.com)