Canon Serenar - compatibility?

[connloyalist]

I would appreciate some help. I vaguely remember reading somewhere that Canon M39 / L39 lenses that are marked "Serenar" are not quite compatible with L39, and that the Canon M39 lenses that are not marked Serenar are compatible. Something about the threads being a slightly different pitch (is that the right word)?

Regards, C.

[visualopsins]

https://forum.mflenses.com/please-help-me-understand-the-versions-of-m39-mo-t81977.html

[DrBB]

I'm using Serenar 5cm f2 on my M4/3 cameras and its working with "standard" LTM39 adapters . From what i see, all cheap adapters have some "wiggle" space (focusing past infinity) so this info is not 100%

[connloyalist]

[kathala]

I can only speak from my own research, not actual experience, but the latter only mentions this issue with the VERY early lenses, i.e. the late 1940s' 50/3.5 Seiki Kogaku -> Seiki Kogaku Serenar -> Canon Serenar, and states it was done for fear of patent violations.
I remember reading that this fear abated eventually, and now, when looking at the production years, I also realise why: by the late 40s, all German patents had been annected and voided by the US invaders. Canon's fear of patent violation in question would have been being sued by Leica. That was no longer a concern, and they adopted M39.
But I will stress that from actual experience, I can only speak to post-Serenar lenses.
You might find this of help? https://docs.google.com/spreadsheets/d/1XHrXeijkKB_ULZxcgJK_v4iPBbxAfOuuo-VuP5ESDvA/edit?gid=0#gid=0

[Huffy49]

I own three Serenar lenses: 50mm f/1.9, 85mm f/2.0. and 35mm f/3.5.
All have standard LTM mounts and function normally on My Leica IIIA, my Canon 7, and my Leningrad.

[connloyalist]

I found this:

Source: https://mikeeckman.com/2022/02/canon-original-hansa-1935/

[John Shriver]

Canon didn't start making cameras with Leica-style rangefinder coupling to the lens until 1946, when all German patents were invalidated worldwide as a war reparation. The earlier rangefinder cameras used a very strange mount with the helical part of the camera.

They did make some non-rangefinder J-mount lenses during the war.

I think they were just bamboozled by Leica's deliberate obfuscation of the LTM mount. It's 39mm thread diameter, but with 26 turns per inch. Mixed units. The J-mount is 1mm thread pitch, which is 25.4 threads per inch.

The threads-per-inch of the mount isn't something Leica could patent. But the cam on the lens pushing a roller on the camera was patented. That's why the Zeiss Contax cameras used rotation of the in-built helical as the rangefinder coupling, a much more obtuse design. (The patents remained in force in Germany after the war.) The very complicated Contax shutter was also a dodge of Leica's patents.

For a few years after Canon switched to the correct 26 threads/inch, they cut the threads on the camera mounts loose enough to accept lenses with either thread pitch.