Zenit SLR M39 lens to rangefinder L39 via extension tube?

[glaebhoerl]

I recently bought a silver Helios 44 at a flea market. As I discovered afterwards, it has the curious Russian M39 mount for some Zenit SLRs, which is physically compatible with the usual rangefinder leica thread (screw?) mount, but with a much longer register distance (based on some internet research most likely 45.2mm, whereas the "usual" distance for rangefinders is 28.8mm).

Now what I was wondering is - for use with a digital mirrorless camera, of course I could try to look for a special Zenit M39-M42 adapter which I believe exists, but wouldn't it perhaps be simpler to just add an extension tube to the LTM adapter I already have, to make up for the missing distance?

In fact I found a listing on eBay for a tube with precisely the right length (28.8+16.4=45.2).

I just want to make sure before I click the buy button: is there any reason this wouldn't work?

[newst]

I have a MIR-1 and Helios 44 with the same issue. M39 thread mount but not Leica compatible. The solution on mine was to get a simple m39-m42 step up ring and use a standard M42 adapter.

[tb_a]

Both versions will work. Actually the mid size ring of the standard Russian 3 ring set M39 is exactly the right ring (16,4mm) to use M39/Zenit lenses on a M39/LTM camera as e.g. the Zorki or any other RF camera in Leica standard.
I've just checked that with my MIR-1 on the GXR-M.
Especially the smallest ring of that set (7mm) is very usable for closer focus with LTM lenses as their minimum focus distance is rather long.
My ring set comes from FED.

Here would be the right one (actually 4 ring set): http://www.ebay.at/itm/FED-Macro-Extension-Tubes-Set-of-4-rings-with-M39-screwmount-FED-Zorki-Leica-NEW-/391058600385?pt=LH_DefaultDomain_0&hash=item5b0ce8b1c1

Cheaper than your offer.

[philslizzy]

I made my own. But you can get one in a set of adapters such as this - cheaper too Click here to see on Ebay

[TAo2]

Helios 44 register's 45.5mm...

[blotafton]

I have a mir 1 and jupiter 11, and also stack m39- m42 and m42- eos adapters. The mir 1 works great but the jupiter 11 miss infinity by a hair, focus is about 20-30 meters out. What to do?

[tb_a]

[glaebhoerl]

According to what I've read, Russian M39 SLRs and lenses were made with both 45.2mm and 45.5mm register distances. I have reason to believe that mine is 45.2mm (it came attached to a body which is purported to have that specification:). It seems easily conceivable that adapting a 45.2mm lens to M42 (which is 45.5mm) will cause it to fall just short of infinity focus - although some M42 adapters seem to be deliberately shorter than the spec (at least on mine, all of my lenses focus past infinity), so it's possible that with some luck, the two would cancel out and it would work out fine. But this is another reason why the extension tube solution is more appealing to me: it seems like less of a gamble. Thanks for the comments!

[blotafton]

Yes the m42 - eos adapter might indeed be the issue. A helios 44-2 can just barely overshoot infinity on it. Thanks.