What thread mount did sovjet rangefinder cameras u

I have tried to find information about the thread mount on pre war FEDs and postwar FEDs and Zorkis.
True Leica LTM is 39 mm x 26 tpi Whitworth. I have read that the pre war FEDs to uses M39 x 1 mm DIN.
There is a slight difference between these two mounts (26 tpi = 0,976 mm). So mounting a M39 x 1 mm on a Leica can give problems.
But what happened after the war ? What mount did FED and KMZ use for their rangefinder cameras ? Still the M39 x 1 mm - or the true Leica LTM mount ? Did they use the same mount ? Some sources says that FED used a true Leica LTM after the war. Help appreciated. . .

Hi!

At first read I was wandering, wasn't there a warning that prewar Feds tend to have LTM and later became everything metric M39x1? I wasn't sure, don't have a pitch meter, so I gave it a try, look what I've found out:

I took my Leica(III), Zorki, Zorki-4, Fed, Fed-4, Zenit-C and their lenses (Elmar, rigid Industar-22, Jupiter-8, Fed, zebra Industar-61, Industar-50 + a later Helios-44, and out of curiosity an Industar-69 from a Chaika II) and cross-mounted them.

The result: every lens did mount on every other camera without any problems, EXCEPT the Fed and Elmar, which were a bit harder (though not impossible) to mount on the Zenit-C!

Any thoughts?

Hello,
Normally, you can cross mount all these lenses on any LTM body (Leica, Fed, Zorki...), even if screwing is not very easy. It is often useful to clean the screw because of old grease...

But beware: it is said that prewar Feds are not really standardized as lenses and bodies were adapted one by one at the factory (even if I cross mounted some of these lenses and never had any problem).
More important: some Helios and Industar were made by KMZ for the first Zenit. So you can put them on a Fed or Zorki, but the 28,8mm distance will not be respected.

Amitiйs. Jacques.
PS: about prewar metallurgy: the screw of one of my very early Fed lens was sawn to fit exactly the body . Certainly, it is original...

Hello,
I have just found a very interesting list with the soviet lens specifikation:
http://www005.upp.so-net.ne.jp/chatvert/soviet/svlens.html

According to this list the early prewar FED lenses had FTM mount (FED Thread Mount, M39 x 1 mm ???), and only after the WWII - LTM.


Regards, Alexander

I got the opportunity to measure the threads on 14 different 'LTM'
lenses on a profile projector at the Technical University here in
Copenhagen.

The results are quite clear.

ALL russian LTM lenses (and also a couple of Zeiss lenses where the
mount has been changed to LTM) I measured use 39 x 1 mm.

All Leitz lenses and a couple of Cosina LTM lenses (Voigtlдnder)i measured use 39
mm x 26 TPI (= 0,977 mm)

There are slight variations of course - and measuring on just 2 - 3
threads is not always easy.

Thanks for that very valuable information, Frede. Confirms what I had long suspected, but been unable to prove. It also confirms that it is a VERY bad thing to mix Russian lenses and Leica cameras, even if they appear to fit!

I just bought a FED lens (50mm f3.5, old aperture marks, uncoated, serial no. 5337) for my mu4/3 E-P2
I'll report back how does it fit my m39 adapters.
I assume I'll have to shave the adapter for correct focusing; my Kazan Industar 22 can't reach infinity unless the barrel is unlocked and moved backwards by a hair, so I planned to shave a couple of adapters anyway.

When I have the three lenses (FED, Kazan I-22 and 1952 KMZ I-22) I'll send any useful data to the relevant databases.