Talk:M39 lens mount

LTM 26 tpi versus RMS thread 36 tpi

Why did Barnack choose 26 tpi when the RMS specification was for 36 tpi? 26 tpi is very close - 0.977mm - to a metric 1mm pitch. Would a 39mm x 26 tpi and a 39mm x 1mm be interchangeable? David.Boettcher 11:24, 16 July 2012 (UTC) — Preceding unsigned comment added by Fsbr1908 (talk • contribs)

The LEICA optics thread is not an M 39. A metric thread with an imperial pitch doesn’t exist. The nominal diameter of the LEICA thread is 1.535 inch, a size common with microscope setups. Leitz was a big player in microscopy equipment, not the biggest and not the first, though. So we have to speak of the 1.535"-26 thread which is only 0,011 mm or 0.000433" smaller than 39 mm. The rest is history. --Filmtechniker (talk) 06:58, 9 April 2022 (UTC)

Soviets

"The Soviets in the 1930's failed to understand this and so produced their early FED cameras in M39 (39 mm by 1 mm DIN thread), a mistake made again after the War in Japan by Canon on their early RF cameras." -- Don't think that the Soviets and the Japanese were an idiots... KengRu (talk) 18:02, 11 February 2009 (UTC)

The Soviets defenitely used the 1mm winding. It was the kind of "optimisation" of very-close-to 1mm winding of original non-DIN thread. To top this: Soviets had to different back focal plane distances with this mount: the original Leica one for rangefinder cameras and an increased one for SLR. See, e.g. [1], [2]. — Preceding unsigned comment added by 137.248.75.191 (talk) 13:25, 30 November 2011 (UTC)