Short history (2/3) In 1931 a screw collar with 39mm was introduced. This allowed to interchange (adjusted) lenses to a designated body (latest 3 numbers of lens and body where equal). With the Leica I (Modell C) a fixed flange focal distance of 28,8mm (between screw collar and film plane) was introduced. To differentiate from the predecessors a “0” was engraved in the screw collar and the lens body. From this point in time lenses with the “True Leica Thread Mount” (LTM) could be interchanged among all bodies. Already in 1932 the Leica II was introduced. It had the first time the revolutionary split image range finder incorporated.

Leica II with 50mm Elmar 1932