The M3 introduced several features to the Leica, among them the combination of viewfinder and rangefinder in one bright window, like on the Contax II, a bayonet lens mount, and rapid film advance lever.

[3] The M3 has a high magnification factor of 0.91×, which is useful in critical focusing, and especially with long lenses (subsequent Leicas would use 0.85×, 0.72× or 0.58×).

This full parallax compensation is limited to one metre; closer distances require special "Leica glasses" as described above.

For fear of tearing the film, early M3s had a double stroke advance lever, like the Neoca 2s would.

Loading of the film is done by removing the bottom plate, like on the Leica II and III series.

A door flap on the rear of the camera can be raised, allowing for easier access to the film, thereby overcoming a problem associated with these earlier screw-lens-type Leicas.

The film is inserted from the bottom of the camera after the user has pre-attached the leading end to the take-up spool.

The Leica 24x27 was a camera with neither rangefinder nor viewfinder, made for the postal service to photograph electricity meters.