Help with marking on summar

[John Shriver]

The exact start point of the threads on the lens and mount isn't well-controlled. As they wear, the lenses screw on "further".

I think the source (for different pitch) was the post-war military report on the Leica factory. Can't find it at the moment.

 

[ChrisLivsey]

I think the source (for different pitch) was the post-war military report on the Leica factory. Can't find it at the moment.

This is the report, part 1 link to part 2 at the bottom:

http://www.angelfire.com/biz/Leica/page26.html