Is it possible to use an Industar 22(50) 3,5/50mm lens with digital cameras? Of course, yes! You will need an adapter from M39 thread to your camera mount . For example m39 to Sony Nex adapter.

Industar 22 (50) installed on Sony Nex 7 using M39 to Sony E bayonet

Industar 22 (50) installed on Sony Nex 7 using M42 to Sony E bayonet, extensions tubes, m39 to m42 ring

Below some samples, first picture - only with lens installed on camera, 2&3 - macro images of motherboard, taken with extension tubes.