There have been several threads which deal with this issue in more detail than I can. Suffice to say that the Nikon lenses are extremely highly regarded. However, while the lens mounts on the "S" series of rangefinders and the Contaxes are the same, the lenses for each are not the same. There is a difference in focusing between the Nikon "S's" and the Contaxs. Nikon made some lenses for the Contax, but most for the Nikons. The wide angle lenses and in my experience the "normal" 50mm lenses have been satisfatory on both my Contax IIa and my Nikon S2 and SP, and, for that matter on my Kiev 4a and 4am. The longer lenses are supposed to exhibit the focusing difference, so that a Nikon lens built for a Nikon will not focus correctly on the Contax or Kiev, and visa versa. Again, I don't see a problem when I use my 85mm Jupiter, designed for a Contax, on my Nikon, but the general wisdon is that I should. Perhaps I am not particular enough. In any case, as the focal length of the lens increasing, the focusing problems also increase. For a fuller and better technical discusion of the point, see Steve Gandy's "Cameraquest" site. Dave
