The M39

lens mount A lens mount is an interface – mechanical and often also electrical – between a photographic camera body and a lens. It is a feature of camera systems where the System camera, body allows interchangeable lenses, most usually the rangefinder ...

is a

screw thread A screw thread is a helical structure used to convert between rotational and linear movement or force. A screw thread is a ridge wrapped around a cylinder or cone in the form of a helix, with the former being called a ''straight'' thread and t ...

mounting system for attaching lenses to 35 mm cameras, primarily

rangefinder A rangefinder (also rangefinding telemeter, depending on the context) is a device used to Length measurement, measure distances to remote objects. Originally optical devices used in surveying, they soon found applications in other fields, suc ...

(RF) Leicas. It is also the most common mount for Photographic enlarger lenses. True Leica Thread-Mount (LTM) is 39 mm in diameter and has a thread of 26 turns-per-inch or threads-per-inch (tpi) (approximately 0.977 mm pitch) of Whitworth thread form. Whitworth threads were then the norm in microscope manufacture. The Royal Microscopical Society (RMS) thread, also known as ''society thread'', is a special 0.8" diameter x 36 tpi Whitworth thread used for microscope objective lenses and Leitz was a major manufacturer of microscopes, so the tooling at the plant was already set up to produce the Whitworth thread form. The Soviets in the 1930s produced their early FED cameras in M39×1 (39 mm by 1 mm

DIN DIN or Din or din may refer to: People and language * Din (name), people with the name * Dīn, an Arabic word with three general senses: judgment, custom, and religion from which the name originates * Dinka language (ISO 639 code: din), spoken ...

thread). Early

Canon Canon or Canons may refer to: Arts and entertainment * Canon (fiction), the material accepted as officially written by an author or an ascribed author * Literary canon, an accepted body of works considered as high culture ** Western canon, th ...

cameras also used a different M39 × 24 tpi thread mount, called "J-mount". True LTM lenses have a

flange focal distance For an interchangeable lens camera, the flange focal distance (FFD) (also known as the flange-to-film distance, flange focal depth, flange back distance (FBD), flange focal length (FFL), back focus or register, depending on the usage and source ...

of 28.8 mm, though this is of little importance for lenses used on bellows enlargers. The Soviets later adopted the LTM mount for their Zenit single-lens-reflex (SLR) cameras, though with the longer optical registration of 45.2 mm, required to allow the mirror room to flip out of the focal path when a picture was taken. The mount was developed by

Oskar Barnack Oskar Barnack (Nuthe-Urstromtal, Brandenburg, 1 November 1879 – Bad Nauheim, Hesse, 16 January 1936) was a German inventor and photographer who built, in 1913, what would later become the first commercially successful 35mm still-camera, sub ...

at Leica to provide a system that would allow for the exchange of lenses on their new small film cameras (Leica Type 1 and Leica Type 2), as

Zeiss Ikon Zeiss ( ; ) is a German manufacturer of optical systems and optoelectronics, founded in Jena, Germany, in 1846 by optician Carl Zeiss. Together with Ernst Abbe (joined 1866) and Otto Schott (joined 1884) he laid the foundation for today's mu ...

had indicated that their forthcoming Contax rangefinder cameras would have interchangeable lenses. The LTM system was tested at the request of Leitz on lenses manufactured in small batches by Hugo Meyer in Germany and marketed with a run of Leitz cameras by A. O. Roth in London. The test marketing program was a success, so regular production with Leitz camera bodies and lenses was introduced on the Leica II, and featured on the Leica Standard and Leica III. Until the 1950s the 39 mm mount was the norm for exchangeable lenses in

rangefinder camera A rangefinder camera is a camera fitted with a rangefinder, typically a split-image rangefinder: a range-finding focusing mechanism allowing the photographer to measure the subject distance and take photographs that are in sharp focus. Most v ...

s. The high cost of quality lenses led to the dual use camera/enlarger of the lenses, hence the fact that

enlarger An enlarger is a specialized transparency Image projector, projector used to produce Photography, photographic prints from film or glass Negative (photography), negatives, or from reversal film, transparencies. Construction All enlargers consist ...

s also accept 39 mm lenses. Currently,

Cosina is a manufacturer of high-end Optics, optical glass, optical precision equipment, cameras, video and electronic related equipment, based in Nakano, Nagano, Nakano, Nagano prefecture, Nagano Prefecture, Japan. History Cosina is the successor ...

in Japan — many of whose recent products are marketed under the

Voigtländer Voigtländer () was a significant long-established company within the optics and photographic industry, headquartered in Braunschweig, Germany, and today continues as a trademark for a range of photographic products. History Voigtländer was fo ...

brand — and FED in Ukraine continue to produce camera bodies using a true Leica thread-mount. Adaptors are available to use M39 lenses with mirrorless digital cameras, such as the Canon EF-M, Sony E or Nikon Z mounts.

References

Sources

Leica vs. Soviet mounts & focus
*

*

* Marc James Small. Non-Leitz Leica Thread-Mount Lenses: a 39mm Diversity. Rita Wittig, 1995. {{DEFAULTSORT:M39 Lens Mount Lens mounts Leica thread-mount lenses

See also

References

Sources