Leica M Lenses

Leica M rangefinder bayonet, introduced in 1954 | 35 mm rangefinder and full-frame digital M bodies

Leica M replaced the earlier thread mount with a faster bayonet interface and frame-line coupling, beginning with the M3 in 1954. It kept the short rangefinder register that makes compact wide and normal lenses possible, while improving handling for professional reportage, documentary work, and street photography.

The mount's constraints are as defining as its freedoms. Lenses must work with rangefinder coupling, viewfinder frame lines, and limited close-focus travel, but they can avoid SLR mirror clearance and do not need autofocus motors or electronic aperture mechanisms.

That combination produced many famously compact Summicron, Summilux, Elmarit, Noctilux, and APO-Summicron designs. In the catalog, M-mount formulas are especially useful for studying how high correction, small size, and mechanical rangefinder usability compete within a long-lived 35 mm system.