Check that the Finger type cam follower does not slip below the Cam of the adapter. The RF Cam on FSU lenses such as the J-3 is thick. The RF cam of this adapter is not, and it is made to work with a Wheel type pickup. It will NOT work on my Zorki 3M, the Cam follower slips below the RF cam and Jams.Thanks. If I will adjust my fed-2 camera rangefinder focus on this sonnar 50mm 1.5 lens will it work properly?