Schneider-Kreuznach Unknown Wartime Thread Mount

[Ox Bird]

I have run into a thread mount that I have not (knowingly) observed before. Lens is a 1941 or 1942 Schneider 150mm, Serial Number 1775528. I thought that it would turn out to be a 39mm mount.....but is smaller than that. Seems to measure approx. 37mm, although this measurement is not likely to be exact.

Lens is smaller than either M39 or M42. It is, therefore, also smaller than lens mount for the Reflex-Korelle.

I have photographed this lens next to a lens of similar age and focal length for comparison. Comparable lens has an Exakta mount.

I cannot find any information about this lens mount anywhere.....

What sort of thread mount do I have???

[Ox Bird]

After more thinking, I decided to see if this lens would actually screw into a Leica thread-mount body......and it does. Also threaded onto a Ploot's mount.

At the same time, my trusty Micro 4/3 adapter's threads will not engage this lens' threads at all......nor will the threads of a pre-war factory back lens cap engage the threads of this lens. So...............I am still a little bit puzzled over the way this mount is behaving with my various M39 stuff....???????

[kryss]

M37?

[Ox Bird]

What early 1940's creation would an M37 mount fit???

I just tried an M39 to M42 ring adapter on this lens..........It is completely loose and does not engage threads at all. The same adapter has been used on several different Soviet M39 mount lenses which need to be mounted on an M42 adapter to do infinity......and they fit to that adapter perfectly. Seems that either the tolerances are way off......or there is something else that I do not understand. ?????? This is driving me crazy.

[Lloydy]

If you put the lens on a M39 mount - is the register distance the same as M39?

[Ox Bird]

The register distance seems to be appropriate with a regular M39 adapter on my Micro 4/3 Lumix. So far, the best indication of this has resulted from simply holding the lens in front of the sensor and varying the distance to the sensor to determine the potential of infinity focus at the various positions of the lens vs. the sensor......

It seems strange that this Schneider will thread onto my Leica IIIF and will also thread onto a Ploot reflex housing mount. It will absolutely NOT engage threads with the same Chinese M39 adapter that accepts the Summitar lens which normally occupies the mount of the same Leica IIIF body. I tried another Leica lens (200mm 1937 Telyt) in this mix with identical results. The Schneider's threads will solidly engage with an old "Exlei" M39 adapter.......which is the only way that I have been able to mount it to my Lumix, thus far.......so........I have concluded that there are tolerance issues on both the lens and the Chinese adapter.

I have ordered a new M39 to Micro 4/3 adapter.....and will give that a try. With as many M39 lenses as I own, I could probably use another one regardless.

I wish this lens could talk. A 1941 or 1942 build year would indicate a military use of some sort, I suppose.....????

[luisalegria]

Looks like its got finer pitch than M39x1
You can thread finer pitch thread on coarser, for a few turns anyway, before it binds. It does depend on tolerances also.
You sure it's got Leica RF back focus ?

[Ox Bird]

luisalegria.....I believe that you may be correct about the threads being finer.......and compared to a Leica lens, the threads of the Schneider lens have a longer shank depth....several more turns.

As far as back focus is concerned.....the only way I know how to test this lens and get an immediate result is to put an M39 adapter on my Lumix body.....hold the lens against the adapter.......and see what the image looks like......and it is too dark out right now to test infinity. I was able to focus it reasonably across the room, though.......I will test it tomorrow.

I am wondering it this lens is some sort of weird movie camera mount.....???......or an odd military lens of some sort. The age of this lens makes it suspect for this sort of original job. My optics collection is growing to include a bunch of Leitz, S-K and Zeiss glass with wartime serial numbers.......and none of the camera lenses have military engravings. The German Government of that time did not cut off consumer goods production as severely as was the case in the U.S., but it surprises me how much of this stuff is on the market right now. I see tons of it on eBay.

[Lightshow]

If those lenses are of similar construction, it looks close to the Exakta lens on the right, which is far from a RF lens registration, but does seem to mount on a shorter mount than it

http://www.graphics.cornell.edu/~westin/misc/mounts-by-register.html
https://en.wikipedia.org/wiki/Lens_mount
Wrayflex M41.2×26tpi (But you say it's smaller than M39)
Argus 38mm thread
Robot M26×0.5 thread (My vote)
Asahiflex M37x1 (post war, so rules it out?)
Early Tamron T mount, M37 x .75 (post war, so rules it out?)
I couldn't find a matching one here: http://collectiblend.com/Lenses/Schneider/

[Ox Bird]

I can tell you that on my Ploot (early Visoflex), it becomes basically a macro. At the same time, held flush against the M39 adapter, it won't focus to infinity.

Almost seems like it is a Reflex-Korelle lens.......but the mount is way too small.

This lens was made to fit something.......but the question is WHAT????? I am totally puzzled. Such a pretty lens as this one must find it's purpose!!!

[iangreenhalgh1]

That thread mount clearly isn't original otherwise it would be plated like the Exakta mount. Painted brass suggests an aftermarket conversion job which was very common back then - lots of skilled machinists around and a shortage of new equipment meant a lot of older things were reworked.

[exaklaus]

It might have an adapter screwed on the original mount? Did you check, if the black painted part will unscrew?
Maybe a lens for Praktiflex (M42) or Exakta (should have a hole for the fixing screw)?

[casualcollector]

Peter Dechert's book on Canon rangefinder camera's explores compatibility issues. He claims that early Japanese efforts assumed the the Leica Thread Mount was 39mm diameter by 1mm pitch. He concluded that in reality the LTM diameter is 39mm but the thread pitch is 26 threads per inch, very slightly finer than the 25.4x that equals 1mm. Threads made to precise tolerances will bind, threads made to loose tolerances will screw in further.

[luisalegria]

Well, its not Korelle or any other medium format slr because the back focus seems to be @4-5mm shallower than Exakta. That would not permit any mf mirror box. I had a Korelle mount 18cm Schneider Tele Xenar and it was much shorter than your two.
It looks like a straight conversion or variant of the Exakta SLR lens.

I'm thinking there might be a good argument for it being a conversion for some specialized purpose.

A possibility is it may have been adapted to a front mount on a leaf shutter for some reason. The back focus would not be relevant in such a case but the image circle would be. I doubt it would cover any mf format in such a long tube plus a leaf shutter behind. A specialized 35mm camera would work though.

Mounting on a lensboard on a rangefinder mf camera with a focal plane shutter is another possibility. Like a Speed Graphic. I am not too confident it would cover mf formats though, even with no leaf shutter behind.
Then there is the cine lens idea.

[pdccameras]

I agree with Ian and others that the mount definitely looks after market. I have a few of these in several mounts, and all are plated nicely. Perhaps it was a homemade adaptation to LTM and the machinist just missed when chasing the threads on his lathe, or perhaps it was designed for a better fit on the aforementioned Canon body that had a slightly different thread pitch. You can rule out Robot II - at 26mm, that is much smaller. The original Praktiflex had a 40mm X 1mm Pitch screw mount which is close, but that wouldn't explain why it has an LTM back focus.

Interesting lens!

Paul

[Ox Bird]

In order to give a better view of the subject lens, I have photographed it at a couple of different angles. Gives a little better idea of the nature of the thread mount, which is quite professionally rendered and firmly affixed to the rest of the lens barrel.

I do not doubt the potential of the machine shops of the day to create a beautiful adaptation for a specific purpose. I am simply curious as to what that purpose might be.......and wish to obtain appropriate adapters for current purposes. That said, I am mainly a collector and this lens will spend most of the time enshrined in the paradise that is my lens cabinet.

Next to the lens in the first photographs is Schneider-Kreuznach 180mm Tele-Xenar #1196266, which is a 1937 vintage unit for the Reflex-Korelle. Schneider-Kreuznach 135mm Xenar #156444 is a ca. 1926 lens, also fitted for the Reflex-Korelle or another camera with an identical mount. I am showing these lenses next to the subject lens in order to illustrate similarities in finishes and materials.....especially in the use of brass and enamel in near proximity to other finishes.

[Ox Bird]

See above post....