When I first got this lens, which I don't even remember where and when, I thought it was some sort of disassembled part of a lens, because it has no focusing ring. It's like an enlarger lens. Turns out that this is a rangefinder lens used on some Russian rangefinders and is also compatible with the Contax rangefinder mount. The focusing part of the lens is on the camera body.
There are adapter specifically made for this lens and the NEX/M4/3 but they are pretty expensive at over $100. It's much cheaper to mount it on the helicoid and use it that way. With the 17-32mm helicoid, it's just barely short enough for the lens to focus to infinity. Unfortunately, the Chinese made 17-32mm helicoid is very badly made and it has some play between the parts of the helicoid when new. And now it's basically unusable. I used this lens on the 12-17mm helicoid. Though works, but the minimum focus distance is a lot longer and it has the same problem with its longer brother - bad workmanship. In contrast, the Vivitar 2X macro teleconverter is smooth and solid.
School Bus -- NEX-5N & Jupiter-8M 50mm f2. Click for larger size.
Tiger Lily -- NEX-5N & Jupiter-8M 50mm f2. Click for larger size.
Streetcar -- NEX-5N & Jupiter-8M 50mm f2. Click for larger size.
