Normally a lens matched to the non-standardized Leica C is engraved with the last three numerals of the camera serial number. The illustrations show a 3.5cm Elmar engraved 585 on camera 53585. Camera 49107 is fitted with a 5cm Hektor engraved 107.
The earliest non-standardized Leica C is occasionally fitted with a lens engraved with the entire camera number. Lens 37309 is fitted to camera 37309. Lens 39910 was mounted to camera 39910 (present whereabouts unknown).
The non-standardized Leica C evolved into the standardized model to be followed by the Leica D in early 1932.