Question re Schneider Kreuznach Tele Xenar 180mm f5.5

[yoyomaoz]

I originally posted this on a thread over at this Board's Sony NEX forum but this Lens forum seems more appropriate to the question I have so I have therefore copied the full text from that other forum to make it easier for people to find and respond to it.

"I recently bought a Schneider Tele Xenar 180mm f5.5 in Exakta mount. Variants of this lens were made for both medium format cameras and for 35mm film cameras. Mine is for the 35mm system. However I found when I received it that the lens will not focus to infinity. At first I concluded that most likely someone had disassembled the lens for cleaning (the helicals are unusually smooth for a lens of its age so this fact points in that direction) but if so then it seems likely that the helicals have then been reassembled incorrectly affecting its ability to focus at infinity. This still seems a strong possibility and I have negotiated a refund with the seller who seems like a very reasonable and nice guy. We both realize that if this is the problem, then fixing it without skills (I know next to nothing about working on Schneider lenses, personally) is likely to be difficult especially if the helicals have been reassembled incorrectly - we would all be aware of the long involved trial and error required to correct this when it happens.

But as an after thought and on examining the lens more closely I also found that the Exakta mount on the base of this lens is actually a removable after-market adapter marked "Telesar Japan". It mounts onto a L39/M39 thread mount on the end of the lens barrel. It therefore looks very much as if an after-market Exakta mount has been screwed onto the lens at some point perhaps in the mistaken (??) belief that this was designed to be an Exakta lens. At least this is a possibility and it is that which I am trying to get some clues about. I have tried to mount the lens on a standard LTM L39 to M4/3 adapter and place it on an M4/3 digital camera but again the lens will still not focus to infinity. This gives rise to the possibility that the lens was designed not for a Leica mount camera (which is unlikely in any event given that this lens lacks the rangefinder actuator that should be found on such a lens if it were designed for a Leica) but instead it may have been designed for a Zenit camera which many here would understand uses the same 39mm diameter mount as the Leica Thread Mount but has a different lens register distance (i.e. 28.8mm register for the LTM and 45.2 register for the Zenit). The difference is 16.4mm as discussed in the original thread to which I am attaching this post - you can see a picture in the thread i refereed to above. (see here: http://forum.mflenses.com/using-zenit-m39-mount-lenses-on-sony-a7ii-t76767.html) Clearly such adapter / spacer rings are or were available but there is little point in me trying to hunt one down if in fact Schneider never even made lenses for the Zenit system.

So, before going to the time and trouble of hunting the internet for a 16.4mm adapter ring to allow a Zenit lens to be mounted on a standard LTM to M4/3 adapter with correct infinity focus I want to ask this question: Does anyone here know if Schneider Kreuznach made lenses for the Zenit system. I cannot find anything confirming or denying this on the internet but if the answer seems to be "no they never did" then it will not seem to be useful for me to hunt for such adapters on the internet.

PS I also just found this thread (below) which indicates that other L39/M39 variants exist too. Is it possible that the Schneider lens may have been made for one of these systems instead of Zenit? (Again I would discount any rangefinder system since this Schneider lens lacks the rangefinder actuator which means it was more likely for an SLR or mirror box such as the Visoflex if not the Zenit. I should also add that when I screwed this lens onto the normal L39 to M4/3 adapter (that I also use for my Leica thread mount glass when mounting onto digital cameras) it screwed on quite comfortably, with no evident looseness or binding even though some of the L39/M39 variants listed below have slightly different thread pitch and or teeth per inch.

https://fotodiox.freshdesk.com/support/solutions/articles/17000083341-m39-l39-ltm-lsm-whats-what-

[kypfer]

Trying to establish what was available for the Zenit 39mm mount can be very long-winded. My first SLR was a Zenit 3m and I distinctly remember having a 28mm Lithagon for it, and very proud of it I was too, but the lens went with the camera when I "upgraded" and I've not been able to find reference to a Lithagon in that fitting anywhere, but I know they existed!

As for the Schneider, I'd anticipate, if it's "natively" 39mm thread, it's possibly for a Braun Paxette, but there were one or two other German cameras that seem to have been produced primarily for the home market that used a 39mm fitting that wasn't the same as "Leica-39mm" or "Zenit-39mm", even though the screw-thread itself is similar, the distance from the lens mount to the film plane differs.

Good luck

[dickb]

So if I understand your question correctly you are asking how much extension you need to get the correct infinity focus. Well, that is fairly easy to determine, just put the lens in front of your camera plus adapter and move the lens until you get far away things in focus and then measure the gap between lens and adapter. This is the distance you need to bridge with a new adapter, or extension rings, a helicoid or bellows.

I have seen Schneider Tele Xenars in M39 used on Novoflex bellows, but those were 180/4.5. Maybe the 5.5 was used as well.

[yoyomaoz]

[yoyomaoz]

I am still struggling to understand what this lens could have been made for and to some extent the mystery deepens. I stumbled recently on a list of serial numbers and the corresponding manufacture dates for Schneider lenses and found that the number on my lens corresponds to a manufacture date of 1937. On the face of it this means it would not have been made for Paxette - these cameras came out in 1951 and as I understand it the early Paxette cameras had fixed lenses - interchangeable lenses came a few years later. So this specific lens is perhaps 20 years too old to have been designed for that make of camera.

But on close examination of this lens, compared with other Schneider tele Xenars of similar build type, the others I have observed have all have a characteristic lens mount. Quite apart from the fact that the one on mine is M39 and others I have looked at tend to be Exakta mount lenses the style of the mount on others is different- they have a silver chrome ring fitted to the base of the lens by small screws. (See the photo in my post immediately above in which you can see more or less what I am talking about though its a small image) Whereas on my lens the mount is an m39 thread which looks as if it screws directly into the base of the lens barrel almost without any join being visible. It looks to me as if someone who may have owned this lens in prewar days and perhaps used it on an Exakta had it modified by a skilled machinist for a Paxette after the war by removing the standard Exakta mount and replacing it with one having a fabricated M39 ring. At least that is my working hypothesis as it would be an easy task for a machinist requiring simply that the lens barrel be cut at the correct length, threads turned into it to allow a new mount to be fitted and a new M39 mount be turned such that it screws into the base of the lens barrel at the correct distance. I have tried to unscrew this mount by hand to test this but its very tight though there is a tiny hair thick gap where the barrel and the new M39 mount join.

To get to the bottom of this the following is my plan. As the flange focal distance for a Paxette is only about 1.5mm less than that for an M42, one cheap and quick way to get a handle on this question is for me to buy a cheap ($2) m39 - M42 adapter ring thread and use that to mount my lens on a cheap M42 to M4/3 adapter. As this thread adapter goes inside the M42 thread effectively to turn it into an M39 thread, and does not sit on top of the m42 adapter it does not add any thickness to the adapter stack. When mounted this way on an M42 adapter my Schneider lens as currently configured will almost, but not quite be at the correct distance from the sensor if my hypothesis is correct - it will still be 1.5 mm more or less too far out. This will mean that infinity will not be reached given the 1.5mm difference in flange focal distance between a Paxette's requirement and that for an M42, but if the lens was modified for a Paxette as I now suspect, it should never the less at least give me enough evidence to confirm that the lens is intended for a Paxette. If I am satisfied, then its a matter of me turning approx 1.5mm off the M42 to M4/3 adapter to see if that provides full infinity focus. This need not involve machining as such - as cheap adapters are just aluminium which is comparatively soft, it can be done with coarse abrasive / emery paper glued onto flat surface and lots and lots of rubbing of the face of the adapter against the flat abrasive face.

That perhaps will not be the end of it. If it works and I am happy with the lens but unhappy with the mounting arrangement or work involved to use a modified M42 mount adapter, ultimately I may actually buy a more permanent solution in the form of an M39 to M39 adjustable helical extension ring and mount this on an M39 to M4/3 camera adapter. This set up would allow me to finesse the adapter thickness to whatever ultimately is required to make it work correctly at infinity. But it's not especially cheap as a solution as the requisite M39-M39 helical costs about $55 including postage. In any event we will see.

[luisalegria]

Schneider made lenses for many systems.

Possibly this is set up for the Visoflex, or similar. That is the Leica reflex system. There were many copycats in the 1950s-early 60s. Originally they were M39, but with a much deeper back focus of course.

Quite a lot of lenses were set up for Visoflex or similar systems by default. Kilfitt and Komura to name two.
At one time the long lenses from both came in M39, with a series of adapters for other mounts.

These reflex adapters did not all have the same back focus, I have found. The Visoflex is rather deeper than Komuras own reflex system, commonly sold with Canon rangefinders. On an original Leica Visoflex the Komuras don't reach infinity.

[yoyomaoz]

luisalegria wrote:

Schneider made lenses for many systems. Possibly this is set up for the Visoflex, or similar. That is the Leica reflex system. There were many copycats in the 1950s-early 60s. Originally they were M39, but with a much deeper back focus of course. Quite a lot of lenses were set up for Visoflex or similar systems by default. Kilfitt and Komura to name two. At one time the long lenses from both came in M39, with a series of adapters for other mounts. These reflex adapters did not all have the same back focus, I have found. The Visoflex is rather deeper than Komuras own reflex system, commonly sold with Canon rangefinders. On an original Leica Visoflex the Komuras don't reach infinity.

Yes I meant to mention that I had considered the Visoflex mount as a possibility. But when I researched it I quickly discounted this as the first version of the Visoflex (the one which uses the M39 mount) has a flange focal distance (FFD) which is quoted in tables of FFD I have read of 91.3mm which is far longer than my rough estimates of the FFD of my Schneider - Yesterday I "eyeballed" the FFD on my Schneider lens by mounting a jury rigged extension ring on an M39 to Micro 4/3 camera adapter to see if I could estimate the FFD when hand holding the lens at or near the front face of the extension ring (it cannot actually mount the lens as the front of the extension ring has the wrong lens mount). So far as I can see it appears to be around that of the M42 mount plus a few millimetres (??? - its hard to judge when hand holding lenses in this manner but in any event a Visoflex is far longer so I did mentally discount it).

But I am still a bit "stumped" as to what mount system using M39 as its base could have an FFD slightly longer than M42 i.e. 45.46mm. Leica R (47mm FFD) might be possible but this would assume that some kind of M39 to Leica R adapter was available back in the day so the two could be mounted together. (Some are available on the internet today and given M39 was used to mount lens heads on bellows systems etc way back then this may have been the kind of thing was going on here - i.e. someone has converted a Schneider Exakta(?) lens to M39 mount in order to mount it on a Leica R camera using a convenient and commercially available M39 - Leica R adapter ??????)

While I discounted the Visoflex system, I had not considered similar mirror box systems existed for "copycat" systems as you say. Though now that I come to think of it I seem to recall at Canon for example had a mirror box for its rangefinder system at some stage. Do you have any ideas about the FFD of alternative mirror box systems that might help.

I think I have a new persona for myself - Hercule Poirot

[jamaeolus]

39mm is surprisingly easy and cheap to get infinity. Get a Nex m42 close adapter. The m39 to m42 rings are like a dollar and a half. Then with the m42 m42 helicoids (which come in many ranges) and m42 extension rings (as necessary) you can easily get infinity. The lens is most likely for the paxette system IMHO.

[yoyomaoz]

If you read my posts in this thread it is about a Schneider Tele Xenar 180mm f5.5 that I bought on eBay. On inspection the lens mount is not the standard Exakta mount - it is an M39 mount with an M39 to Exakta mount adapter screwed onto it. This looks like someone modified the lens mount for some reason.

I have found I cannot get proper focus with the lens at all ranges. My first hypothesis was that the lens had been opened up, serviced (the helicals are very smooth which suggests a recent CLA) but reassembled incorrectly. I then decided that I thought it possible that the lens had been adapted for a camera (or mirror box) with a larger flange distance as the original Exakta lens mount has been replaced with an M39/L39 mount. Interestingly though as stated above, there is also an M39 to Exakta mount adapter also present - which raises a question - why change a lens in this way? I have tried various options to test the idea that the lens was adapted to another camera but cannot find anything that looks likely (and works). Possibly the lens mount was damaged and this is the reason the mount was changed. In any event I am now therefore reverting to hypothesis number one till I work out what in the heck is going on.

I tested the infinity focus using the trick of pointing the lens at the sun (while focused at infinity) and placing a target behind the lens to gauge the distance at which the rays seem to converge / focus. The point of maximum focus seems to be very close to the lens mount - too close to make sense as the distance is shorter than any flange distance I know, which suggests something is wrong and the entire optical block is too far away from where it should be inside the lens. (A symptom sometimes associated with helicals assembled incorrectly).

I tested the lens further on a camera, using the Exakta mount / adapter and found that using this arrangement I can get good sharp images at ranges of 2-3 metres but it is impossible to get focus at any distance much beyond this (so at worst I may be able to use this as a portrait lens). In fact the sharpness of images at that shorter distance looks very good. This is further evidence that seems to reinforce the thought that the source of this problem is that the lens has been serviced and the helicoids have been incorrectly reassembled (which is probably why the lens was sold - though I must say that in my case the seller was excellent and returned my purchase and mailing cost while allowing me to keep the lens).

I then also tested the lens on a camera using its M39 mount and found that I can get infinity focus (just - everything closer is way out of focus) but only when the lens is racked out to its MINIMUM focusing distance. I found this confusing given that when the lens is mounted with its Exakta adapter it behaves as if the lens elements are too far away from the sensor. It still confuses me (perhaps someone has an explanation).

The lens I am referring to is very like the 105mm f3.5 version by Schneider (a lens I also own and which I like very much) depicted below.



My question is this: does anyone here have experience in opening these specific lens designs for servicing or repair? They both look as if the lens head / forward optical block should just screw off (as indeed they do with say a Leica Elmarit 90mm f2.8 and many others) . But when I try this (the silver ring immediately below the focusing ring looks to be where it should unscrew) I have found that either it is screwed on ultra tightly or something else is going on. I do not wish to force it in case some damage is done - I have been down that path with another lens and do not wish to repeat it. Both lenses are equally tight in this respect. There are no obvious grub screws / locking screws on this ring point although there are some on the focusing ring which is immediately above - these seem serve another purpose. According to references, some Schneider Tele Xenars of this design do have a removable lens head for use in enlargers etc - but references I have found make no mention of whether this is one of them. I should have thought they all do however, given they are all of a common virtually identical design.

Does anyone have any ideas and in particular experience they could pass along?

many thanks Peter

PS I find these tele xenars to be lovely for portraits. They exhibit the characteristic sharpish but not too sharp / round look that is classic for good lenses from this era. They represent the type of lens I enjoy using most of all as they do the job nicely without the clinical look of modern lenses.

[kiddo]

I've found a xenar 150mm 5.5 in Exa mount, but can't find any info about it. It's a multi blades early version, black and chrome serial number starting 3222...,
Wonder if it's got anything to do with your 180mm lens? Do you have any pics taken with yours ? Thanks

[iangreenhalgh1]

In the 40s and 50s it was common to see large format lenses repurposed for smaller formats by having them mounted in tubes, the qualty of the work varies from 'done on someone's kitchen table' to 'as good as from the factory'.

[Pancolart]

This Schneider is usually found on Reflex-Korelle. Mount can be removed and replaced with all variations described above.

[paulhofseth]

Fellow experimenters:

My theory is that this Schneider lens may have been made to fit the VP-Exakta which has a peculiar screw thread and dates from jjust that pre -WW2 period well before Braun made any Paxettes.

Looking at the Tessar 75mm of my Kodak Vest-Pocket film device, the thread is definitely not Leicadimensioned 39mm but i do not have my measuring device at hand.and leave to other tinkerers to confirm.

p.

[kiddo]

[kiddo]

Is this exakta mount?

[iangreenhalgh1]

Yes and a fairly common lens too:

https://mwclassic.com/product/schneider-150mm-f5-5-tele-xenar-coated-chrome-manual-focus-exakta-mount-lens-caps-leather-case/