The Leica M3
1954 to 1966
Leica’s first M-mount camera combined a bright viewfinder and rangefinder in one window, with frame lines for each lens and a quick bayonet mount.
How it began
The screw-mount Leicas that followed the Leica I had a separate rangefinder and viewfinder, and lenses screwed in slowly. In 1954 Leitz showed the M3, a new design with a bayonet mount, the M.
How it works
The rangefinder image sits in the middle of a large, bright viewfinder. When a lens is mounted, the camera shows a matching frame line, which also corrects for parallax as you focus. Lenses lock in with a quarter turn.
Why it mattered
Its finder was the brightest and most accurate of its time. The M3 sold more than 220,000 units and was used for some of the best-known reportage of the 1950s and 60s. It reportedly persuaded some Japanese makers to turn from rangefinders to SLRs, where they could compete.
Limits and what replaced it
Rangefinders cannot show exactly what long or close-up lenses see. The SLR, led by the Nikon F, took over professional work in the 1960s, but the M line continues.
Today
The M mount is still in use on Leica’s digital M cameras, more than 70 years later.