For your amusement, I have done a little article that covers the following. I think Michael Darnton is right, and that Soviet lenses are incompatible with Leica bodies for the same reason that Nikon lenses don't go on Contaxes. This also has some basic information that discusses how RF couplings work. Here are the sections:

Main link

(1) How rangefinder cams transmit distance to a lens

(2) Why Nikon and Contax RFs stuff is not mix-and-match< br>
(3) Why Soviet and Leica (Canon/Cosina/Hexar) RF stuff is probably not mix-and-match< br>

-- Dante Stella (dante@dantestella.com), June 06, 2002

Answers

Dante; Interesting web article..

The origin of the Leica cam movement is from the first leica lens; the lens cam moves with the lens block as one assembly...An old Leica Rep showed this to me 40 years ago....For a telephoto lens; or wide angle; ie a non "52"mm lens requires a double helix..All my Nikon; leica & Russian telephotos have this....Long ago each Leica lens was measured for the exact focal length ; and slightly different pitch lens mounts were made for each focal length group.....In the 50mm group they were one set of groups for the 50mm Elmar; and another set for the other 50mm lenses...

My personal opinion is that the Russians never did anything like this; this is pure opition as an Optical Mechanical Engineer...

I posed the question of sorting focal lengths to custom helical mounts to a Russian camera board and got alot of flak; like it is really easy to produce exact focal length lenses...

I have measured the lens mounting flange to rear lens cam surfaces on many of my LSM lenses...I measure them at the infinity and 3 meter setting....I am working on a test fixture with a dial indicator to make the job easier....

This is an interesting aeaa; the Russian lenses....; and non Leica optics

A Russian camera maybe setup to focus at infintity to closeup the same as a Leica..this is because it has the infinity adjustment and the closeup adjustment also (the length of the cam arm determines the gain; just like my Leica M3......In fact some of my favorite Russian cameras are setup to match my M3.......

If one has an off tolerance lens; the camera maybe setup to match that one lens......But this creats a freak body which will not track with my leica M3....................

The Jupiter-9 is my favorite good/bad soviet lens...Many have been regreased and reassembled wrong,, the darn things are like the rubic cube....3 multithread helixes to muff up! many on ebay are goofed up Jupiter -9's ( 85mm F2 ) I bought 3 and have one that is ok.........

All my good lenses are from Ebay sellers in the Ukraine or Mother Russia....The USA sellers tend to sell their crap that does not focus correctly.........My not so hot photos of the Jupiter-3's performance ruffled a few feathers on the Russian camera board....The design is similar to the 50mm F1.5 Xenon or Summarit; which Erwin Puts stated " The performance of the lens at full aperture is however barely acceptable for its intended use." - from Leica Lens Compendium.........My test shots for the two Russian J3's at F1.5 show their performance on my M3.....The sharpest area on the negative is the test chart and negative; there is not focus or cam problem here................But my test shot of my Industar -50 F3.5 rigid is fantastic.........Kelly

-- Kelly Flanigan (zorki3c@netscape.net), June 07, 2002.

Kelly: I don't doubt that the 50/3.5 works well - but that lens doesn't require a very accurate focusing cam, or even a very accurate rangefinder mechanism. And a 50/3.5 lens design is pretty well known. The 50/1.5 and the 85/2 are the consistent poor performers (by the way, the 50/1.5 is a copy of a Sonnar, which has fundamentally different - and if properly executed, superior - design than a Summarit or a Xenon).

-- Dante Stella (dante@dantestella.com), June 07, 2002.

The ultimate test of the correctness of the focus mount is to take the glass out of the question. Put your camera on a tripod and focus your leica lens on something at exactly one meter, making sure the lens reads exactly on the one meter mark. Then do the same with the Russian lens. Do the numbers read the same? None of mine do--all of my Russian lenses focus several inches back. The pictures from them show the same thing. No engineering opinions on what the Russians might or might not have bothered themselves to do are necessary. :-)

As Dante says, a 50/3.5 isn't much of a test. That's why they supplyed rangefinderless pocket cameras with them. As for correct assembly--the order of error we're discussing here is not that of a displaced helix, nor does it appear at infinity, as an assembly problem would.

I doubt very much that American Russian sellers sell only their crap. From the stuff I've gotten from them it appears that they don't even look at what they sell more than enough to confirm they're putting the right thing in the box--these are $50 lenses, after all, and the sellers aren't Zeiss. What are they doing with the good stuff-- sending it back to Russia so you can buy it? :-)

-- Michael Darnton (mdarnton@hotmail.com), June 07, 2002.

I've never been very fond of the "Russians are incompetent" line of logic for this question, by the way. It obscures the possibility of looking for intent and reason with a pat insult, and the result gets the search for a solid answer nowhere.

-- Michael Darnton (mdarnton@hotmail.com), June 07, 2002.

Blaming problems on QC, carlessness or incompetence seems to be a fairly common tactic among Leicaphiles. I tend to think that the difference is by design, since it is the rare exceptional Soviet lens that works like a gem on a Leica body. It kind of blows the theory about QC being a problem, since in that case bad QC could be leading to a more usable lens!

A 50/3.5 has huge depth of focus and much wider depth of field than a 50/1.5. A 50/3.5, by its optical properties, can mask problems in rangefinder alignment, back focus, and even some manufacturing tolerances. And it's not a challenging lens to build.

-- Dante (dante@dantestella.com), June 07, 2002.

What is interesting to me is that my ancient 50mm F3.5 @f3.5 Industar- 50 is sharper than my 1000+ dollar new Summicron LTM 50mm F2 @f2...

Both lenses are sharper that my 2700dpi scanner; thus unless I really need the F2 aperture; I am better off using my Industar-50 on my M3; and leave the expensive F2 on the shelf....My M3's rangefinder was recently adjusted at close and far distances; using my Noctilux ..It took 5 iterations to get the cam arm length spot on.........Later the lens test photos were shot....If the Industar tracks focus at all distances; I fail to see why there are opinions that the Russian lenses are built to different "nominal" standards.......The increased DOF @f3.5 is not going to be enough to mask a missfocus error when focused at 2 meters or 1 meter..

The shot with the Summicron @f4 and the Industar-50 @f4 are similar.....I showed the results to some unbiased people at work that do not know cameras...they picked the Industar 5 to 7 over the Summicron.......The Summicron was beat by a 25 dollar Industar- 50...............Maybe I got a lucky lens.....

The LSM lenses I own have been measured for the lens cam position versus lens rear flange distances..This is at the infinity focus position; and 3 meters.....I have measured Canon,Nikon,Bessa,Leica,Steinheil, & Russian lenses.......The dimensions vary abit on each; but the Russian lenses are centered around the non Russian LTM dimensions; with more scatter.........The one with the largest offset from the group is the Canon 50mm F1.2 LTM...Old worn out Russian lenses tend to be short a mil or two; the soft aluminum wears; or is dented (watchout for this!)......

Since the mechanical dimensions of the Russian lenses cam surface dimensions average out to be in the middle of the other lenses; I must conclude as an Optical Mechanical Engineer that the Russian lenses cam is built to the same nominal specs as the other LTM lenses.....

The Russian lenses that alot of people use are off because they were not shimmed correctly in assembly or after relubing...There is a shim that sets the lens block in the lens helical mount........One Jupiter -9 85mm f2 I bought was off a mighty 0.6mm; the duffus probably mixed up the shims with another serial number lens during relubing .........Typically relubed Russian lens are reassembled wrong; then they are sold on Ebay...the best Russian lenses I own are the ones that have never been disassembled...These work correctly on my Leica M3 at close and far distances...The ones that have been relubed tend to have focus problems..Their lens blocks are set in the lens mount at the wrong position.......This is not a Leica versus Russian body problem; but a BAD LENS; do to poor assembly at the factory to start; or BAD relubing/rebuild........

MANY of the Ebay sellers get boxes of the dead Russian Jupiters that are too stiff to use......They used a bogus grease that went bad too quickly....They pay some old retired guys in the Ukraine to relube the lenses.....Some of them like the Jupiter-9 are like rubic cube to reassemble; I have taken apart three of them......They can be a nightmare to reassemble correctly.................Thus the Russian lens quality varies alot due to poor QC in the shiming area of the lens block....

As a practical matter; I would prefer to use my Industar-50 on my M3; and my Noctilux if I really need extra firepower...The Industar-50 meets or beats my new 50mm F2 Summicron from F3.5 to smaller apertures......Too many Leica nuts have their egos such they cannot use a non leica lens on their camera....If my Russian lens will beat the leica; I am going to use it alot....

When you find a russian lens that works well on your camera; maybe you might use it too if it beats the Summicron.....it weights alot less and looks plain; one gets better shots; people think it is just a toy....Kelly

-- Kelly Flanigan (zorki3c@netscape.net), June 07, 2002.

but dante -- even assuming youar rite, only the normal uses the built in helical. all of the other lenses have their own focus helical. if these are rite at infinity, they certainly wouldn't care which body they are on. since nikon made separate nikon and contax versions of many of its lenses, thus acknowledging a difference accross the board (i.e. not just with the 50 that used the built-in helical), there must be a nother difference. and that difference has to be helical pitch.

-- roger michel (michel@tcn.org), June 07, 2002.

to state it differently -- and perhaps more simply -- even assuming that the built in helical in a nikon is geared for a different focal length than the contax (a very reasonable assumption since no nominal 50 is really a 50 in my experience), why would that in ANY way affect the use of other contax lenses on nikon RFs (or vice versa) since they have their own buolt in helicals AND DO NOT RELY ONTHE BUILT IN 50 HELICAL IN ANY WAY. as you note, the back focus distance is the same. this is all that matters. the only answer is that there is a difference in pitch for ALL of the lenses. this is why nikon had to make different versions for all focal lengths.

-- roger michel (michel@tcn.org), June 07, 2002.

No - infinity focus is not the only thing that matters. If that were true, you could always mix and match Contax and Nikon. And you can't.

It is the pitch of the rangefinder helix. A rangefinder helix imitating a 51.6mm lens moves less as you go from infinity to 1m than one set up to imitate a 52.3mm. Using the built-in helix does not help when mixing and matching because you are now combining a helix for a 51.6mm lens (the Nikon built-in helix) with an optical unit whose focal length is 52.3mm (Contax). 50mm lenses don't present no problem - just a different one than wides and teles.

-- Dante Stella (dante@dantestella.com), June 07, 2002.

And with wides and teles, even with built-in helicoids, the translation gets screwed up. When you put a Contax wide or tele lens on a Nikon body, the rangefinder helix (simulating a 52.3mm lens) moves forward too much. Vice-versa, the Nikon lens moves forward too little. This gets covered up with wideangles, where accurate focusing is a little less important. < P>Roger, the incompatibility between Contax and Leica is not conjecture: Nikon specifically mentions it on their site, and the incompatibility, especially with normals and teles, is well known in the field.

-- Dante Stella (dante@dantestella.com), June 07, 2002.

Dante; the Kiev / Contax / Nikon is yet another weird can of worms!..regards Kelly

-- Kelly Flanigan (zorki3c@netscape.net), June 07, 2002.

dante -- if you agree that the pitch is different then we are in perfect agreement. and i am well aware of the incompatbility contax/leica!!

-- roger michel (michel@tcn.org), June 07, 2002.