"My Russian lens focuses correctly on a Leica" - Oh no it doesn't

[wlaidlaw]

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It never fails to amaze me that some folks still insist that "Their" Soviet period LTM lens focuses perfectly at all distances wide open on a Leica body camera. They will produce small thumb nail images to prove this, all taken with undisclosed apertures at a single distance. Why won't they believe that this is just physically impossible, unless the RF cam has been expensively built up and reground. This is for the very simple reason that historically, going back to the 1920-30 period, when Zeiss assisted with technical advice to the nascent Soviet camera lens industry, the Soviets opted to use the Zeiss focusing helicoid thread pitch. This is different to the helicoid thread pitch, which Leica have used, since they first made LTM (39mm x 26 t.p.i.) removable lenses in the 1920's. If you look at the back of a Soviet era RF coupled LTM mount lens, you will see that the rotating RF cam is curved, not flat like the Leica rotating cam on their single helicoid lenses, e.g any of the Summicron 50 lenses series 1 LTM to series V M mount. For those of a technical bent, Dante Stella explains this at some length but very clearly here: https://www.dantestella.com/technical/compat.html .

I have referred people to this article and they come back still believing that their Soviet lens is different. I can only assume this is a form of self delusion and not wanting to admit, even to themselves, they have bought the wrong lens for their camera. Yes they may be in focus at certain distances and may work acceptably when well stopped down but that is all. I always tell people looking for a "cheap" lens for a Leica camera - buy Japanese. The Japanese camera industry opted to use the Leica helicoid thread pitch on RF demountable lenses, even for the Nikon Contax type RF mount, which is, of course, why the Nikon lenses do not focus correctly on a German Contax RF camera body. These Japanese LTM lenses focus perfectly on Leica and Leica type bodies, LTM and M mount with an adapter ring but not on Soviet LTM bodies. 

The only exceptions to the above are the recent re-issues of classic Russian Jupiter lenses by Lomography. They have now been optimised to focus correctly on Leica and other similar bodies (Voigtlander, Konica Hexar, Zeiss ZM, etc). Conversely, these new lenses will not now focus correctly on a period Russian body (FED, Zorki, etc). 

Wilson

[Pyrogallol]

Very interesting and informative. I have just read this immediately after posting my latest experiences matching my non-standard Elmar with a similarly non-standard FED body. 

Edited August 17, 2019 by Pyrogallol

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[Jerry Attrik]

Thank you Wilson.

A timely piece of advice.  My 3f is 'away for c.l.a.' and I don't expect to see for at least 3 months; 6 months when I sent it.

I have been toying with buying a stand-in body and have been reading up on Fed with a view to using my Leitz lenses.

I do have a second 3f but that has colour neg. in it. The one away I use for mono.

I might just keep on mooching and humming until my own returns.  Saves me a penny or two.

D.Lox

Edited August 17, 2019 by Jerry Attrik
trying to reduce the line spacing ???how?

[jerzy]

interesting article, indeed. Will need some time to read and understand :-)

But in one thing he is not quite correct: when Leica made the dual-range Summicron, it made focusing mounts for several different actual focal lengths. Then optical units could be matched with the mounts that would focus them the most accurately.

It was much earlier, already Elmar 5cm had different mounts for different focal length - focal length group stamped beneath the focus tab

 

 

[Stacey]

Part of the issue likely is the "sled" on the focus arm rather than a roller. The distance between the pivot and the contact point of the rangefinder arm stays the same with a roller. With the flat slider, the distance between the arm pivot and the contact point on the lens cam changes, which has been calculated in the soviet camera/lens combo. This is all interesting to me because I have a 50mm f1.5 Jupiter 3 that when used on a Sony A7 was one of the sharpest of the 50mm LTM lenses I tested. But used on my Leica IIIc, it was horribly soft wide open up close but seemed much better at infinity. I have a zorki that works well and think I will give it a try on that body.

[tranquilo67]

Fully agree. My only point here is that nowadays there is a culture of "good enough". Today we consider that things like rebooting from time to time is acceptable and, even more, that such device is working.

So, unfortunately, as per today standards they work. Of course, when you compare them with the real thing that really work, where the precision is everything, adjusted and tested one by one, the difference is amazing.

I have a few Soviet lenses and cameras (some early samples as well as some samples from right after WWII) and they can have some interest but let's keep in mind that they are what they are. They even not screw properly in the mount of a Leica screw.

So once more, fully agree but I'm afraid it's a lost war.

Best regards

Edited August 28, 2019 by tranquilo67

[wlaidlaw]

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I believe some Russian M39 lenses are 1mm thread pitch rather than 26 threads per inch. 1mm thread is equivalent to 25.4 threads per inch. If both the "Leica" camera body and Russian lens are well worn, these lenses may mount OK, otherwise they will often bind after about two turns. The LHSA and I did some research about 9 months ago on the origin of the 26 threads per inch on the Leica M39mm lens mount, when a 1mm thread pitch might have seemed more logical. It is probably due to the fact that Leica were a microscope and attendant lens maker, long before they were a camera maker. Firstly it was a convention (still applicable today) that microscope objective lenses use imperial threads (26tpi was in common use) and secondly the machinery to cut those threads was often made in Great Britain with no metric thread capability (127 tooth change gear needed). It is believed that the thread cutting machinery in use by Leica in the mid 1920's, was not metric. 

Wilson

[wlaidlaw]

I have just had a quick look on a couple of auction sites, a Japanese one and eBay. There are 35mm Canon LTM lenses for sale in considerable numbers and various apertures. There are some at less than £200. IMHO a far better buy than a Russian to use on a Leica or Leica compatible body. 

I have just had a look at the latest Wetzlar auction catalogue and I see they are expecting high prices for early Russian FED and  Chinese Zhongi cameras. That will teach those people who converted them into Leicas 😀

Wilson

[david strachan]

Hi Wilson

Agree with you regarding Canon ltm's from Japan.  I have quite a few and always buy from Japan.  The dealers present their lenses immaculately and usually truly represented. Very good lenses with lovely build.

...

[Stacey]

And as far as a backup body for a Leica, I would also recommend buying a camera made in Japan. Honestly am not super impressed with the Canon Barnack clones (but the later ones are OK/better than any russian models), and the Minolta isn't any better. But the later Canon L1 (and some of the other models from that time) is a jewel of a camera. While not as compact as a Barnack style, has a built in rotating finder feature that allows it to natively work with both 35mm and 50mm lenses, as well as zoom in for focusing. The back opens for loading like a film SLR which is also very nice. For a Barnack clone, look at the Tower/Nicca LTM models. Very solid camera and some of the later ones were made with a lever wind. The model 5 even has a back door like an M to make the bottom loading easier. I recently picked up a Tanack which is off for a CLA. I haven't used it yet but this also feels like a solid Barnack style camera, but has an opening back like a film SLR, which makes loading so much easier.

[BrianS]

On 8/17/2019 at 6:57 AM, wlaidlaw said:

It never fails to amaze me that some folks still insist that "Their" Soviet period LTM lens focuses perfectly at all distances wide open on a Leica body camera.

Wilson

MY Jupiter-3 focuses perfectly on my Leica at all distances when used wide-open.

 

https://static1.squarespace.com/static/5baa8b54a9ab95602839e52f/5bab8361ee97cc8dac6f07a0/5bab8357ee97cc8dac6efd18/1537966935425/Jupiter-3-Focal-Length-Adjustment.pdf?format=original

 

https://static1.squarespace.com/static/5baa8b54a9ab95602839e52f/5bab8361ee97cc8dac6f07a0/5bab8357ee97cc8dac6efd1a/1537966935427/Jupiter-3-Shimming-Instructions.pdf?format=original

 

https://static1.squarespace.com/static/5baa8b54a9ab95602839e52f/5bab8361ee97cc8dac6f07a0/5bab8357ee97cc8dac6efd15/1537966935422/Jupiter-3-Exploded-and-Labelled.pdf?format=original

 

https://static1.squarespace.com/static/5baa8b54a9ab95602839e52f/5bab8361ee97cc8dac6f07a0/5bab8357ee97cc8dac6efd13/1537966935417/Jupiter-3-Clean-Lube.pdf?format=original

 

So do my Sonnars.

 

https://static1.squarespace.com/static/5baa8b54a9ab95602839e52f/5bab8361ee97cc8dac6f07a0/5bab8357ee97cc8dac6efd1c/1537966935430/Jupiter-3-Contax-to-Leica-Conversion.pdf?format=original

 

I've taken apart some 300 Jupiter-3, Jupiter-8, and Zeiss 5cm F2 and F1.5 lenses. Most require adjusting the shim for close-up and wide-open use, stop down to F2.8 for Infinity where Sonnar focus shift brings it into sharp focus. You can adjust the focal length by moving the rear group in.

 

Interesting- the Summarit actual focal length is shorter than the RF calibration, the 5 that I've taken apart were all scribed "51.1". They are optimized for wide-open at F2.8. I moved the rear section out on mine to increase the focal length to optimize for wide-open/close-up.

Edited October 6, 2020 by BrianS

[BrianS]

One more "Piece to the Jupiter Puzzle", I found this data sheet a few years back. It lists the focal length and allowed deviation.

52.4mm +/- 1%. That gives a range of ~51.9mm to 52.9mm.

Lenses on the short end of the range are going to focus across range on a Leica, well within the DOF. Those on the long end need the focal length reduced. Those in the middle- increase the shim 0.1mm, and use F2.8 for infinity where the focus shift moves actual focus towards infinity.

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[wlaidlaw]

1 hour ago, BrianS said:

One more "Piece to the Jupiter Puzzle", I found this data sheet a few years back. It lists the focal length and allowed deviation.

52.4mm +/- 1%. That gives a range of ~51.9mm to 52.9mm.

Lenses on the short end of the range are going to focus across range on a Leica, well within the DOF. Those on the long end need the focal length reduced. Those in the middle- increase the shim 0.1mm, and use F2.8 for infinity where the focus shift moves actual focus towards infinity.

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Not quite correct. The problem is not mainly that of the focal length or flange focal distance. It is that the pitch of the focusing helicoid is different for Leica compatible and Russian lenses. So whereas you can set them up to be in optical and RF convergent focus at one particular distance, at distances shorter or longer than that, it is just not possible for the lenses to be in perfect focus using RF image convergence. The Russian lenses are designed to operate with a curved RF cam and a flat plate RF operating lever with a curved contact surface. The Leica compatible lenses have a flat RF cam, whose plane is at right angles to the optical axis and are designed to interact with a roller on the RF operating lever. The reason for using the different helicoid thread pitch is historical. At the end of the 1920's, it was Zeiss who helped the Soviets with setting up their nascent camera lens industry. This is evidenced by even the pre-war Russian lenses strongly showing Zeiss ancestry. The focus pitch helicoid is the same as Zeiss used at the time. The reverse situation applies to Nikon RF cameras and lenses, where Nikon used the Leica helicoid thread pitch, so that although the Nikon lenses will mount on Contax RF cameras (and vice versa), they will not focus correctly. Interestingly with a view to selling more of their lenses in the west, Lomo have recently re-issued the 50/1.5 Jupiter 3 (Zeiss Sonnar based design) modified to be fully Leica compatible. I don't know if they have done this with a specially shaped RF cam or have adopted the Leica helicoid thread pitch.

Wilson

[BrianS]

The movement of the RF cam to the optical block is 1:1. The absolute travel distance does not make any difference for actual focus to the RF.

The distance scale of the focus ring will not agree with measured distance. So- if you focus by using a measuring tape, the focus will beoff.

The actual focus of the lens and the RF will agree. As the movement of the helical is farther on the J-3, you can focus slightly closer once the helical is calibrated for infinity.

Take apart  couple hundred of these lenses, and you learn some things. The pitch of the helicoid makes no difference, the travel of the RF cam is the important factor.

 

The Jupiter-3+ is built to the Leica focal length, it uses 1:1 travel for the optical block to motion of the cam. I have two. I have 12 J-3's. All focus perfectly on my Leicas.

 

The Nikon S-Mount has less travel than the Contax mount. The pitch of the helicoid is the same between both cameras, the rotation of the helical on the Nikon is about 10degrees less than the Zeiss.

 

Dante sent me his J-3 to set straight.

 

I've taken a lot of actual measurements on these lenses,  worked out the math for shimming them to work on a Leica and moving the elements to work on a Leica. I don't argue with the Laws of Physics- just try to find the actual measurements for the equations. Feel free to post your measurements and your math.

Edited October 6, 2020 by BrianS

[BrianS]

Jupiter-3 on my Leica M9, distance shot.

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[BrianS]

Same Jupiter-3, on the Leica M9, same visit to Gunston Hall.

Wide-Open, close-up. Focused using the RF on the camera, 1.25x magnifier.

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Edited October 6, 2020 by BrianS

[BrianS]

1963 ZOMZ J-3, on the Leica M9.

A little farther distance shot.

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[BrianS]

The Test pictures with Dante's lens after I rebuilt it, all at F1.5.

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[BrianS]

For anyone interested in having a Jupiter-3 adjusted for their Leica, or having a CZJ 5cm Sonnar converted to Leica mount- Skyllaney in the UK now offers this service professionally.

I read Dante's article when he first published it, and wanted to investigate first hand. I bought 7 J-3's, took them apart and made some measurements. Offering to adjust Jupiters on RFF gave me access to a lot of them. Skyllaney does this professionally, has a real shop to do it. The point is: yes, the Jupiters are made to the Zeiss standard. The equations for back focus and focal length yield the answers for using these lenses on a Leica. I have Eight CZJ 5cm F1.5 Sonnars and Twelve Jupiter-3's that all focus like these samples show. The equations and measurements are in the links in my first post.

Edited October 6, 2020 by BrianS

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[BrianS]

I recently converted two 1930s Carl Zeiss Jena 5cm F2 Sonnars to Leica mount for a friend of mine, have the full resolution images uploaded to Flickr. Had been a few years since the last conversion. I used my M9 and M Monochrom to test the two lenses. The optimization for the M Monochrom accounts for using a deep color contrast filter, which shifts focus towards infinity.

 

Full-resolution JPEGS are uploaded to the Flickr albums, links here bring up the albums. I use a Jupiter-8 focus mount and move the Zeiss optics barrel into it. Each of these represents about a full day of work. I'm not doing these anymore, and refer people to Skyllaney. I can respect the work that goes into converting them. I've converted about 50 Zeiss Sonnars to Leica mount. The hardest part of doing this is packing them up and sending them to a new owner.

 

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Edited October 8, 2020 by BrianS