Nippon-Kogaku Nikkor 1:3.5 f=5cm Nr.502xxx

This appears to be the last, and rare variation of using the original 50xxx serial number block. These lenses are the first to feature a screw mount for Canon J rangefinders. The mount is similar to the 39mm Leica screw mount, but the thread has 24 turns per inch instead of 26 turns per inch, so they are not compatible.
Related: Previous | Next | 5cm 1:2 Regno | More at Pacific Rim | Home