The really quite inexpensive Nikon-to-EOS adapters sold by many vendors on eBay have allowed me to mount most of my Nikkor lenses on my EOS 20D body,with good results. Of course, the best lenses for adaptation to EOS bodies have mechanical aperture rings, which means Ai, Ai-S,AF, or AF-D, or non-G AF-S Nikkor lenses. The G-series Nikkors are almost useless on EOS cameras,since they have no aperture ring and stop down to minimum aperture....the view thru the 20D at f/22 is really QUITE dim! However, it's no big thing to shoot at f/1.4 or f/2 or f/2.8 or f/4 or even f/5.6 in good light with the lens already stopped down to shooting aperture. I know Nikkors are not Contax lenses, but there are some very useful lenses outside the EOS system and they work well on Canon digital bodies!