+1 for Larry's comment--I have used 85 mm, 135, 50 and 53 mm Russian lenses on my Contax IIIa. The 53 mm Helios is a new acquisition and I haven't developed the test roll of film for that yet, so I don't know how accurate focusing will be. The 35 mm Jupiter 12 is a close copy of the pre WW II Zeiss Biogon and won't fit the post war bodies. Nikon RF wide angles ( I have a 35 mm f/2.5 and 28 mm f/3.5) should fit and focus accurately enough on a Contax. For 85, 105 and 135 Nikkors, look for ones with a "C" on the focusing ring for accurate focusing on a Contax.