The Rubin-1 is a zoom lens based on the Zoomar formula. Maximum aperture is f/2.8 and it has a focal length range from 37mm to 80mm (slightly less than the Zoomar at 36mm to 82mm). The Rubin-1 has 14 elements in 11 groups. It is the standard lens supplied with the Zenit-6 camera. A second version of the lens, in photos 3 and 4 has an added tripod bush and strap lugs. This version was possibly made for the Zenit-5.

David Tomlinson.