The FED 1:3.5 F=50 m/m (Russian: ФЭД 1:3,5 F=50м/м) is a normal prime lens for 35 mm rangefinder cameras with the M39 screw mount.
The lens was manufactured in the 1930's under the name FED 3.5/50 for the prewar FED and Sport cameras with retractable (tube for rangefinder cameras) and rigid barrel. The design had been borrowed from the German «Leitz Elmar». The optical elements are not coated. The lens came as a kit under the trade mark Industar-10 for the postwar FED cameras. (contributed by nondaturis)