You're speaking of the R2C? I have one. Just like an R2 except for mount and added frontpiece that incorporates the focusing mechanism controlled by the wheel. My complaint is that the focusing action is too easy. When I try to change f-stops on the lens, the resistance on the lens is much greater than the focusing resistance. This means that every time I rotate the f-stop ring, the whole lens rotates instead. This means that I either have to put the lens at infinity, or hold the focus wheel. This is a bit irksome. Maybe this is the reason why the f-stop dial on the CV 25mm that I have is sooooooo free. I don't have this whole problem on my Contax IIa. Otherwise, my Zeiss Opton 50mm fits fine in the mount and the RF focusing is spot-on. My 25mm CV in Contax mount fits and works fine using the outer bayonet mount. My 85mm "C" Nikon, however, is very loose in the mount compared to when I mount the same lens on my Contax IIa. The R2C is obviously much more practical to use since it's got a built-in light meter. The shutter clunks loudly compared to the IIa. The IIa is much more stealthy in that regard.