Home
SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

FED / Zorki M39 rangefinder - flange focal distance?
View previous topic :: View next topic  


PostPosted: Wed May 10, 2017 8:50 pm    Post subject: FED / Zorki M39 rangefinder - flange focal distance? Reply with quote

Folks, firstly my apologies - I'm sure this must have been asked many times before, but a quick Google search brought up no obvious answers...

Can I ask, what is the flange focal distance for FED, Zorki and other Soviet rangefinder cameras? I understand that for Leica's L thread mount it's 19mm, but I've read that the Soviet cameras use a similar yet very slightly different distance.

The reason for my question is that I have a few Soviet M39 rangefinder lenses that seem as if they're just about to reach infinity focus on my A7II + adapter, but maybe they don't quite. It's difficult (for me!) to tell for sure, but it feels like they're just not quite there. I'm wondering if the Soviet cameras' flange focal distance is ever-so-slightly less than Leica L... if not, then perhaps it's my adapter at fault (or perhaps the lenses *are* reaching infinity focus and I need to learn to trust that!), although I get similar results from two different manufacturer's adapters. Hmmm.

Any info would be much appreciated!

Thanks in advance Smile


PostPosted: Wed May 10, 2017 9:25 pm    Post subject: Reply with quote

The M39 rangefinder cameras from FED and Zorki use the same flange focal distance as Leica M39/LTM: 28.8mm
https://en.wikipedia.org/wiki/Flange_focal_distance
Do not confuse with M39/Zenit SLR cameras where it is 45.2mm.

Edit: Corrected the typo in the FFD for Zenit.


Last edited by tb_a on Thu May 11, 2017 7:39 am; edited 1 time in total


PostPosted: Wed May 10, 2017 11:54 pm    Post subject: Reply with quote

tb_a wrote:
The M39 rangefinder cameras from FED and Zorki use the same flange focal distance as Leica M39/LTM: 28.8mm
https://en.wikipedia.org/wiki/Flange_focal_distance
Do not confuse with M39/Zenit SLR cameras where it is 42.2mm.


Thanks Smile

I'm aware of the difference between rangefinder and SLR M39 mount distances and lenses (I use both successfully with the relevant adapters). But, I also see some Russian rangefinder lenses advertised as being unable to infinity focus on Leica rangefinder bodies, or requiring adjustment to do so Confused


PostPosted: Thu May 11, 2017 4:05 am    Post subject: Reply with quote

BigMackCam wrote:
I also see some Russian rangefinder lenses advertised as being unable to infinity focus on Leica rangefinder bodies, or requiring adjustment to do so Confused


That's actually new for me though I have most of those Russian RF M39/LTM lenses made for the FED and Zorki cameras. However, I only use them on digital (mainly on my Ricoh GXR-M with M39/LTM to Leica M adapter) and there is no problem with infinity focus whatsoever.


PostPosted: Thu May 11, 2017 11:31 am    Post subject: Reply with quote

tb_a wrote:
That's actually new for me though I have most of those Russian RF M39/LTM lenses made for the FED and Zorki cameras. However, I only use them on digital (mainly on my Ricoh GXR-M with M39/LTM to Leica M adapter) and there is no problem with infinity focus whatsoever.


Thanks, Thomas Smile

I think part of the problem is actually me... I have difficulty trusting that infinity focus is correct. If the lenses went past infinity and I could rock the focus back and forth to find the sharpest point, I think I'd have more confidence in it.

I may sand down one of my adapters slightly, just to see if I can improve on it - but, otherwise, I'll just learn to trust my lenses Smile


PostPosted: Mon May 15, 2017 7:28 pm    Post subject: Re: FED / Zorki M39 rangefinder - flange focal distance? Reply with quote

BigMackCam wrote:


Can I ask, what is the flange focal distance for FED, Zorki and other Soviet rangefinder cameras? I understand that for Leica's L thread mount it's 19mm, but I've read that the Soviet cameras use a similar yet very slightly different distance.

The reason for my question is that I have a few Soviet M39 rangefinder lenses that seem as if they're just about to reach infinity focus on my A7II + adapter, but maybe they don't quite.
Any info would be much appreciated!

Thanks in advance Smile


The Soviet lenses have the same flange distance of 28.8mm as the Leica, but the focal length is made to the Contax RF 52.4mm standard. For the Soviet lens to focus correctly wide-open and close-up on a Leica, typically a thicker shim needs to be used, most often 0.1mm thicker. The lens will reach infinity when stopped down as "focus shift" is towards infinity.


PostPosted: Thu May 18, 2017 9:04 pm    Post subject: Re: FED / Zorki M39 rangefinder - flange focal distance? Reply with quote

fiftyonepointsix wrote:
The Soviet lenses have the same flange distance of 28.8mm as the Leica, but the focal length is made to the Contax RF 52.4mm standard. For the Soviet lens to focus correctly wide-open and close-up on a Leica, typically a thicker shim needs to be used, most often 0.1mm thicker. The lens will reach infinity when stopped down as "focus shift" is towards infinity.


Excellent info, and very much appreciated! Thank you! Smile