Quote Originally Posted by Dovaras View Post
Ok.. at the risk of being laughed at... please see attached picture. This is also a Leica 50mm/2 Summicron. Look at the inner copper ring, you can see it through the nickel colored bayonet curve. This is not true on my lens (see photos in 1st post). The inner copper cylinder on my lens seems to have been shaved down. I'm not talking about the machined curve in the lens mount, i'm talking about the copper colored ring behind it. The copper ring in this photo appears to be the same height all the way around, on mine it's shaved down to follow the curve of the mount.
I noticed the same is true on my Type 2 Rigid Summicron. The Leica Rangefinder is calibrated for 51.6mm. The focal length of individual lenses may deviate slightly, and most manufacturers just leave the RF cam flat. The Leica cam is milled to take the deviation into account. By the looks of my RF Cam, the difference is about 0.1mm. The cam is milled to correct for the slight deviation in the focal length of this particular lens from 51.6mm. I suspect this was required when the minimum focus of Leica lenses was brought in to 0.7m from the old 1m standard of the M3 generation lenses.