The bayonet mount allowed lenses to be changed more quickly and made the fitting more secure.

Other innovations introduced by the M3 included a single window for the viewfinder (for composition) and the rangefinder (for focusing).

The M3 was followed by many other M mount cameras, released over 40 years, with many of the basic concepts remaining in these designs.

These lenses are divided by Leica based on their maximum aperture number (also known as f-number).

They are distinguished by their names:[2] • 220,000 produced in Germany • Around 1,500 produced in Canada • Introduction of the "red dot" • Versions: Leica MDa, Leica M4-2, Leica M4-P • First M mount with electronic Through-the-lens metering (TTL) • Leica M6 (1984–1998) • Leica M6 TTL (1998–2002): Better viewfinder and electronic flash capability • Electronic shutter control and semi-automatic mode • Removal of the "red dot" • Manual exposure only • 3936 x 2630 max resolution • 2.5″ inch screen • 5212 x 3472 max resolution • 2.5″ inch screen • 5212 x 3472 max resolution • 2.5″ inch screen with sapphire crystal LCD glass • 3″ inch screen • Capable of capturing Full HD 1080p video • 5952 x 3976 max resolution • 3″ inch screen with sapphire crystal LCD glass • Capable of capturing Full HD 1080p video • 3″ inch screen • Wi-Fi capability • 5952 x 3992 max resolution • 3″ inch screen • Wi-Fi capability • 3″ inch screen • No removable bottom plate • 64Gb of internal memory • 2.5″ inch screen • 3″ inch screen • 3″ inch screen • Capable of capturing Full HD 1080 video • 2.5″ inch screen • Black-and-white version of the M9 • 3″ inch screen with sapphire crystal LCD glass • Black-and-white version of the M (Typ 240) • Capable of capturing Full HD 1080 video • 3" inch screen TFT LCD monitor • Black-and-white version of the M10 • Dedicated ISO dial with ISO 160 to ISO 100.000 • The only control on the body is via the shutter speed and ISO dials • No Rear LCD Screen • The only control on the body is via the shutter speed and ISO dials Mechanical | Mechanical TTL |   Electronic Controlled Shutter TTL Digital types: M = Professional | ME = Entry level | MM = Monochrom | MD = No display MR = Increased resolution CCD sensor  | CMOS sensor  | Video capabilities