OKC1, 50mm f2.0. It is a very rare Soviet cine lens, predecessor of OKC1-50-1. It has an M42 mount that works on Sony A7 with the slim adapter. It covers APS-C sensor (25X17mm). The helicoid is original. The glass is basically clean and transparent. There are very few dust particles inside. I do not see cleaning marks, or just only few that can be barely seen. There is no scratches or haze. There is no oil on the aperture blades (there are 8 blades). The focus ring is smooth an easy. The aperture ring works normally with nice very well audible clicks. The lens is very sharp and contrasty with nice tonal transitions and with a unique bokeh at close distances. The lens hood is build in.
Have a look at my other announcements, too.