There is an engraved black 'C' on the barrel of the Nikkor lenses made for Contax. The 5cm F1.4 will focus 1" too close at 36", either correct for this by focussing a little far. By F2 the DOF should cover the difference. The 3.5cm F2.5 is fine on either camera, DOF covers the error. The mode common Nikkors for 'C'ontax are the 8.5cm f2, 10.5cm F2.5, and 13.5cm F3.5.