M42 lens mount
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The M42 lens mount is a screw thread mounting standard for attaching lenses to 35 mm cameras, primarily single-lens reflex models. It is more accurately known as the M42 × 1 mm standard, which means that it is a metric screw thread of 42 mm diameter and 1 mm thread pitch. It was first used in Zeiss' Contax S of 1949; this East German branch of Zeiss also sold cameras under the Pentacon name; after merger with other East German photographic manufacturers, the name Praktica was used. M42 thread mount cameras first became well-known in Japan under the Praktica brand, and thus the M42 mount is known as the Praktica thread mount there. Since there were no proprietary elements to the M42 mount, many other manufacturers used it; this has led to it being called the Universal thread mount or Universal screw mount by many. The M42 mount was popularized in the United States by Pentax; thus, it is also known as the Pentax thread mount, despite the fact that Pentax did not originate it.
Most SLR camera using a bayonet lens mount are compatible with M42 lenses with the aid of adapter. As of today the use of lenses with M42 mounts is popular on Digital SLR. Digital SLRs made by Canon, Pentax, Nikon, Konica Minolta, Olympus, and other brands are now able to use lenses with M42 mounts provided that they are mounted on adapters. M42 lenses are controlled manually, and some Digital SLRs come equipped with an autofocus indicator that beeps once the lens is manually focused on its subject.
The Tamron T2 mount also uses a 42mm thread, but the pitch is finer at 0.75mm
[edit] Specifications
- Thread: M42x1
- Flange to film: 45.46 mm (front of mount to film plane)
