To install click the Add extension button. That's it.

The source code for the WIKI 2 extension is being checked by specialists of the Mozilla Foundation, Google, and Apple. You could also do it yourself at any point in time.

Kelly Slayton
Congratulations on this excellent venture… what a great idea!
Alexander Grigorievskiy
I use WIKI 2 every day and almost forgot how the original Wikipedia looks like.
Live Statistics
English Articles
Improved in 24 Hours
Added in 24 Hours
Show all languages
What we do. Every page goes through several hundred of perfecting techniques; in live mode. Quite the same Wikipedia. Just better.

M39 lens mount

From Wikipedia, the free encyclopedia

Leitz Summicron 50mm M39 3798.jpg
Leitz Summicron 50 mm in M39 lens mount
External diameter39 mm
Inner diameterN/A
Flange28.8 mm
ConnectorsTelemeter coupling

The M39 lens mount is a screw thread mounting system for attaching lenses to 35 mm cameras, primarily rangefinder (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 thread).[citation needed] Early Canon cameras also used a different M39 × 24 tpi thread mount,[1] called "J-mount".

True LTM lenses have a flange focal distance 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 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 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 1970s the 39 mm mount was the norm for exchangeable lenses in rangefinder cameras. The high cost of quality lenses led to the dual use camera/enlarger of the lenses, hence the fact that enlargers also accept 39 mm lenses.

Detail of the mounting of a Leica IIIf
Detail of the mounting of a Leica IIIf

Currently, Cosina in Japan — many of whose recent products are marketed under the Voigtländer brand — and FED in Ukraine continue to produce camera bodies using a true Leica thread-mount. These give amateurs the rare chance of having a very professional camera by combining a used Leica lens with an M39 body at a price well below a real Leica combination. On the other hand, one has to be careful as there are some issues with some bodies not using the same focusing system. Adaptors are available to use M39 lenses with modern digital cameras, such as the Canon EF-M and Sony E mounts.

YouTube Encyclopedic

  • 1/3
    4 395
    129 734
    14 857
  • Vintage Leica Rangefinder lens thoughts
  • Adapting Lenses to Micro 4/3
  • Fuji Secrets: $50 ~ $100+ AWESOME lenses for your Fuji. WHY aren't you considering it?


See also


  1. ^ [1]. Canon Camera Museum


This page was last edited on 30 April 2020, at 11:41
Basis of this page is in Wikipedia. Text is available under the CC BY-SA 3.0 Unported License. Non-text media are available under their specified licenses. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc. WIKI 2 is an independent company and has no affiliation with Wikimedia Foundation.