These adapaters are for lenses made for the ordinary bayonet mount on Contax cameras with manual focus, not the auto-focus Contax G cameras. First adapter from rainbowimaging on eBay is labeled "Contax/Yashica--m4/3" and works with one small exception: one of my lenses is a bit loose, although it appears to work fine, no loss of focus. Because of the loose play with one lens, I bought a second adapter from fotogearhk on eBay, labeled "CY-G1." All my lenses fit tight. First test shots were out of focus. I discovered that the distance scales on the lenses are wrong with this adapter. A 50mm lens will do infinity focus but at approximately the 25-foot mark. A 28mm lens will do infinity focus at approximately the 12-foot mark. This adapter is 2-3mm shorter than the first one. Have taken only a few test shots. Am I likely to find more problems?