Toronto. The 35mm cameras were off and running in the late 1920s. Leitz touted their Leica as a precision camera and set out to compete with the physically far bigger cameras of the day, claiming that a small negative could produce a suitable big print.
By 1930, Leitz bent to the suggestion to make its minicam with interchangeable lenses. One problem. Leitz had yet to standardize the film to lens flange distance which risked lenses that while interchangeable, would not necessarily focus to infinity.
This was solved by insisting any added lenses only be sold when the camera was sold. The lens serial number was engraved to match the camera serial number (first all 5 digits, and later the last 3 digits). By the following year the film – flange distance was standardized at 28.8 mm and the letter”O” was embossed at the top front of the flange to indicate a standard mount.
Then on any Leitz lens would fit any Leica. The lens shown in this post is an f/4.5 135mm Elmar made in early 1931 for a Leica camera with a serial number ending in 134. The lens design was possibly for a far bigger camera since the coverage far exceeds that needed for a 35mm camera. The special serial was engraved on the lens head mount and hidden by the focussing mount.