This Fotodiox lens mount adapter is made with high standard precision. The leaf spring design in the adapter holds the lens tight to the camera body ensuring there is no play between the camera and the lens. The adapter allows Contax / Yashica (C/Y) Mount Lenses to fit on a Canon EOS Digital camera body.Although the lens will fit physically, automatic diaphragm, auto-focusing, or any other functions will not operate correctly while using this adapter. In this case "stop-down mode" will need to be used when metering since the lens does not have the ability to have its aperture controlled by the camera body. You can shoot with manual mode or aperture priority mode. Infinity focusing is allowed.Compatible Cameras (including, but not limited to): Canon 1d/1ds, Mark II, III, IV, X, C, 5D, 5D Mark II/III, 7D, 10D, 20D, 30D, 40D, 50D, 60D, 60Da, Rebel xt, xti, xs, xsi, t1i, T2i, T3, T3i, T4, 300D, 350D, 400D, 450D, 500D, 550D, 1000DIncompatible LensesAlthough this adapter will fit any lens with a C/Y (Contax/Yashica) mount on it; some lenses are not recommended to be used with the Canon 5D series as that camera has a larger than normal mirror which may hit the rear of the lens during use. Reportedly the following adapted Contax lenses are not compatible with the EOS 5D series:? 18mm f/4? 85mm f/1.2? 135mm f/2There have been conflicting reports on the Contax 28mm f/2.8, perhaps suggesting unreported lens variations. Lens mount variations have been reported on the 28mm f/2.8 and the 35-70mm lenses. These lenses may require about 1mm to be filed from the end of the brass locking latch, before the lenses will lock on the adapter. Take note that if you do this modification, the adapter may or may not lock on other Contax lenses.Actual product packaging and contents may differ from image shown due to packaging or product updates by manufacturer.