The M mount
In 1954, Leica launched the M3 rangefinder camera, which featured a new bayonet lens mount, a high magnification viewfinder, as well as an improved film transport. This was the beginning of the M System we know today. The Leica IIIg, which was launched in 1957, was the last thread mount camera that Leica offered.
However, it is important to note that the new M mount did not spell an end to the now ubiquitous Leica Thread Mount (LTM) lenses. Instead of being an obsolete system, LTM lenses can be mounted on M mount cameras via thread to M mount (LTM to M) adapter rings.
The M system evolved from the initial 3 frame lines to the current 6 frame lines (28, 35, 50, 75, 90 and 135mm) found on most 0.72 magnification rangefinder cameras. Like their thread mount counterparts, all focal lengths beyond these frame lines require the aid of external viewfinders. Subsequent innovations allowed photographers to choose cameras with higher (0.85) or lower (0.58) magnification to suit their requirements. Accessories like viewfinder magnifiers were also available to allow users to further customize their viewing preference and to improve focusing accuracy.
Leica’s exclusivity to the M mount ended when their patent expired in 1998 – the year the M6 TTL was introduced. In the following year, Konica launched the Hexar RF, an impressive M mount camera with all the bells and whistles not found on the M6. The Hexar RF featured all that was on the M6, plus, Automatic Exposure with AE Lock, motorized film advance and rewind, and a wider shutter speed range (due to the improved electronic metal curtain). Till today, the Hexar RF is still very much sought after by photographers. It wasn’t until the M7 was introduced in 2002 that Leica offered AE on their rangefinder cameras. The Minolta CLE is another great little M mount camera with AE, but it does not have frame line compatibility like other M cameras.
The Voigtlander Bessa T was Cosina’s first M mount offering in 2001. It had an integrated rangefinder with high magnification, but it did not have a viewfinder! You would have needed to use an external viewfinder for every lens you owned. The M mount Bessa R2 was introduced in the following year, replacing the Thread Mount Bessa R, which was introduced in 2000. Incidentally, Cosina also introduced the R2 in the defunct Nikon S mount and Contax C mount. Of interest to note is the Bessa R4A and R4M, which featured framelines from 21 to 50mm, including 25, 28 and 35mm. No other rangefinder cameras offer such wide-angle viewfinders on the camera which are coupled to the focusing cam.
Whilst prime lenses dominated rangefinder photography, there are a few variable focal length lens options available. Most notable are the 2 Tri-Elmar offerings from Leica, which offered 16-18-21mm and 28-35-50mm focal lengths on a single lens. Konica also have a dual focal length lens featuring the 21 and 35mm in one neat package. Other notable M mount lenses include the fastest 35mm lens – Voigtlander Nokton 35mm f/1.2 Aspherical, and the fastest 21mm lens – Leica Summilux-M 21mm f/1.4 ASPH.
Text and Picture by Benny Ng.