Pre-War Zeiss Sonnar 5cm/2 on a Bessa T

[raid]

I have a pre-war Zeiss Sonnar 5cm/2 lens that had focusing problems, so I sent the lens to DAG for adjustments. Here is a link for my first test roll. Either I am not focusing well or the lens focuses slightly behind what I am trying to fosuc on (in some photos). What is your experience with a Sonnar (pre-war_ lens?

http://www.photo.net/photodb/folder?folder_id=543939

 

[raid]

Maybe I should clarify more; why do you think my photos seem to be slightly out of focus? Is it the lens or the RF or me? Can the photos reveal something about the source(s) of error here? Somehow, nobody seems to be interested in contributing a reply here. Oh well.

 

[richard_l]

I don't think they look out of focus. The definition is very good, but contrast is moderate to low, and there is a hint of flare here and there. A medium yellow filter might help occasionally, and always use a shade if you are not already doing so.

Okay, I took another look, and the focus does seem to be off on some of the people shots, as if it may be focussing a little behind the subject. I would try to use a smaller apertue if posssible, and let DOF take care of it.

 

[Gabriel M.A.]

It's hard to judge whether they're out of focus or not; we don't know what were the points of focus on each one of these photos.

I'm going to assume that you've taken photos with this camera before with another 50mm f/2 lens, and you never saw an out of focus picture, until you started using this lens, is that correct?

 

[FrankS]

Not too many folks around here have a pre-war Zeiss Sonnar in LTM! 🙂

 

[raid]

I don't think they look out of focus. The definition is very good, but contrast is moderate to low, and there is a hint of flare here and there. A medium yellow filter might help occasionally, and always use a shade if you are not already doing so.

Okay, I took another look, and the focus does seem to be off on some of the people shots, as if it may be focussing a little behind the subject. I would try to use a smaller apertue if posssible, and let DOF take care of it.

I used Ilford XP2 film, so most likely, I had the lens on F11. I just want to make sure it is not the lens that is the cause.

 

[raid]

It's hard to judge whether they're out of focus or not; we don't know what were the points of focus on each one of these photos.

I'm going to assume that you've taken photos with this camera before with another 50mm f/2 lens, and you never saw an out of focus picture, until you started using this lens, is that correct?

If you look at the photos showing my daughter, the point of focus was her face, her eyes. I see the results as soft (not unpleasant though). As for the Bessa T, I got it about 3 months ago and had no such problems.

 

[raid]

Not too many folks around here have a pre-war Zeiss Sonnar in LTM! 🙂

I expect Sonnars from the same time period to be similar in performance, even if not in LTM. I should have clarified this point. The LTM part is just the mount.

 

[richard_l]

If you look at the photos showing my daughter, the point of focus was her face, her eyes. I see the results as soft (not unpleasant though). As for the Bessa T, I got it about 3 months ago and had no such problems.

I assume you've tried the lens on a Leica M, preferably an M3 with a carefully calibrated rangefinder?

 

[Gabriel M.A.]

I see what you're saying. It does seem the focus is farther away from the camera than what you seemingly intended the focus plane to be. Somehow I'm not sure whether subject movement may contribute to perceived lack of sharpness; the last two seem to be right on.

I would try another body, and shoot this lens alongside another 50mm lens which you know is "right".

I've heard of miscalibrated lenses, but I would tend to point the finger at the camera, not the lens. The Telemetro (Bessa-T) does have a high magnification, which is then allowing you to be more precise in your focusing, and therefore, bringing out its misalignment with more accuracy (?).

 

[raid]

I see what you're saying. It does seem the focus is farther away from the camera than what you seemingly intended the focus plane to be. Somehow I'm not sure whether subject movement may contribute to perceived lack of sharpness; the last two seem to be right on.

I would try another body, and shoot this lens alongside another 50mm lens which you know is "right".

I've heard of miscalibrated lenses, but I would tend to point the finger at the camera, not the lens. The Telemetro (Bessa-T) does have a high magnification, which is then allowing you to be more precise in your focusing, and therefore, bringing out its misalignment with more accuracy (?).

In the last two shots I had the camera steadied on some pier posts (like a tripod) and maybe that's why it looks sharp. I may have to do some tests with the M3 and maybe also a Canon VI-L. Maybe the RF in the Bessa is not perfect.

 

[raid]

My bedtime is pretty early, and I had my car worked on yesterday.

This is going to happen with a Zeiss lens on a Leica body. The Zeiss focal lenght is 52.3mm, the Leica RF is calibrated for 51.6mm. The Helical goes straight to the RF cam, no conversion like on a wide-angle or telephoto lens. The trick is to shim the lens so the focus is somewhere in the middle, then DOF covers the short and long distance. I suspect your lens needs to have a different shim. I just corrected a J3 that was focussing more than a foot behind the subject and changed the 0.4mm shim to 1.2mm. Works well close-up, loses at infinity. On a Nikon S2, I added 0.5mm to the spacers used to set the film-flange distance to focus a Sonnar 5cm F1.5. Set the focus to be exact at 8', the DOF covers it at 3' and for distance.

Set the shutter to "T" (or "B" with a cable release locked down), put a film strip with sometging to focus on at the film gate, and use a loupe to check focus. On the J3's, I unscrew the lens from the focus mount to attain correct focus. This is the amount that has to be made up with by the new shim.

This is a shot with a 13.5cm F3.5 telephoto made for the Contax being used on the Nikon S2, wide-open.
http://www.rangefinderforum.com/photopost/showphoto.php?photo=1418&cat=3204

Brian: First, the photo you posted is beautiful. Thanks for your detailed input. I think, you found the problem. DAG added a shimming, but he may not have added the right one. I am sure that he will take the lens back and re-adjust it.

 

[Peter Klein]

Raid: The easiest way to test focus is to put the camera on a tripod, and focus on an inch mark in the middle of a ruler or yardstick that is set at 45 degrees to the lens axis. Take several shots, refocusing the camera each time. Shoot B&W negative film or slides (NOT color neg) and examine the film with a loupe. You can then do a "statistical evaluation" on the photographs--if most of them are correct, your lens is probably OK at near distances. If the lens focuses slightly too far away, it needs a thicker shim. If too close, a thinner shim.

You can test medium distance focus (about 10 feet) by lining up three people, each one slightly to one side and behind the other. Focus on the middle person's eyes. Again, shoot several pictures, refocusing each time. And again, see where the sharpest focus is in the majority of the pictures.

In these tests, it may help to shoot some pictures at f/2.8 or even f/4 rather than wide open. I've noticed that with Sonnar-type lenses it is sometimes difficult to tell where the exact point of focus is wide-open, because it is a broad, slightly soft "hump" rather than a sharp "peak." The focus gets much sharper even one stop down from wide open.

Brian's point about the Zeiss vs. Leica focal lengths is interesting. I have never heard that Zeiss LTM lenses had a focusing problem on Leicas, despite the actual focal length difference. After all, they were actually meant to be put on Leicas, and the cam could have been machined at a slight angle to compensate for the focal length difference. Marc James Small is the authority on such matters, and he wrote a book on non-Leitz LTM lenses. I have it, but it's at home. I'll check it for you tonight. You could contact Marc via the LUG (Leica User's Group) or the Rollei Users Group.

Russian lenses are notorious for this focus problem, however. They use the LTM mount, but were not really designed to be compatible with Leicas. And many lenses that say "Sonnar" on them are actually Jupiter-8 or Jupiter-3 lenses that have been counterfeited by the Kopykats of Kharkov. DAG told me that it is impossilble to get fast Russian lenses to focus correctly at all distances on Leicas. You can get them perfect either near or far, but not both. Shimmed to a compromise in the middle and stopped down, they may be OK.

Hope this is helpful,
--Peter

 

[raid]

Peter: Thanks for your detailed comments above. DAG asked me today to send him back the lens for another inspection.

 

[raid]

Looking at the pictures, the focus mount of the LTM Zeiss Sonnar's looks exactly like the J-3 that copies it. The lens is a double-helical, so the rim that get picked up by the RF wheel of the body does not rotate. I have not used one, would love to get my hands on one, but do not think it is cammed to correct the 52.3mm vs 51.6mm difference. It is possible that the front/rear groups were positioned to narrow the difference, or the lens was made to the different focal length.

Anybody have one?


http://cgi.ebay.com/Carl-Zeiss-Jena...ryZ30063QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Brian: Here is a link to an earlier discussion of Zeiss lenses in LTM. maybe you ahve seen it already, but it does have photos of the lens I am referring to. It is not as nice as the photo of the 50/1.5 Sonnar seen in the ebay ad you have a link to above.

 

[furcafe]

I do, & it does not exhibit any focusing problems w/any of my LTM or M bodies, either close-up & wide-open or @ infinity w/smaller apertures (e.g., http://www.flickr.com/photos/furcafe/tags/carlzeissjena5cm15sonnarltmc194243/). I did have DAG CLA it because the focus helical was stiff, but AFAIK, he did not have to make any optical adjustments. So, based on my limited 1-item sample, I agree w/Peter that, unlike the Soviet/post-Soviet Jupiters, the LTM Sonnars were made to focus properly w/Leica bodies.

Yes, the LTM Sonnars have the same type of helicals as the later Ukrainian Jupiters, but that doesn't create focus problems by itself nor the difference in focal length, it's the distance the helical moves the optical unit. If anyone hasn't seen it, Dante Stella has a good discussion of the issues involved:

http://www.dantestella.com/technical/compat.html

IMHO, I would assume that any regular civilian technician (1 not encumbered w/the concerns & constraints of the Soviet optical industry as discussed in Stella's article) would convert a Contax RF Sonnar to LTM using a proper Leica focus helical, i.e., 1 calibrated for the 51.6mm-v.-52.3mm focal length difference. I would think this would be particularly true for Raid's lens, as it appears (IIRC) to have been made using a focus unit from a Leica/Leica-compatible lens.

Also, if I read Dante's article & its citation of Michael Darnton's test results correctly, the S/PS lenses focus *in front* of the desired focus distance when mounted on a Leica body, not behind it:

"[T]o achieve an indicated lens distance setting of 1.5 meters for a subject at a distance of 1.5 meters it is necessary to focus on an object roughly 2.5 inches behind the desired point of focus (i.e., subject)."

Anybody have one?


http://cgi.ebay.com/Carl-Zeiss-Jena...ryZ30063QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

[furcafe]

I agree w/you re: the optics. However, it is my understanding (& experience) that the helicals used on the Zeiss LTM Sonnars do "translate" the 0.7mm focal length difference so that they focus properly on the Leica bodies. Per Stella's article, the Soviets did not do the same for the Jupiter lenses (which are calibrated for use on the Fed & Zorki bodies).

A simple lens with a longer focal length has to be farther away from the film plane to be at focus at any given distance when compared with a lens of shorter focal length. The Sonnar when mounted on the Nikon S2 focussed about 1" behind the subject at 36". Moving the focus mount out 0.5mm brought things into good agreement. The Russian lenses are all over the place, my J3 originally had a 0.4mm shim and was off by 1' at 4' with the Canon 7. Adding 0.8mm for a total of 1.2mm of shim fixed it.

 

[raid]

Here is the link to an earleir discussionwith some photos.

http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00AwhI

 

[raid]

Raid,

Looking at the photo's and reading the discussion, it looks like the lens module from a collapsible pre-war Sonnar 5cm F2 was mounted into the focus module of an older Elmar. The DOF at F2 should cover and residual error caused by the difference in focal lenght. You can convince yourself by using the lens up-close and wide-open. I did this test with a spider-web at an angle before I re-shimmed the Nikon S2. The focus was 1" behind where the RF indicated at closest focus. The DOF at F1.5 is ~0.7" at 36".

Zeiss Sonnar 5cm F2, uncoated. Wide-open on the Contax IIIa:
http://www.rangefinderforum.com/photopost/showphoto.php?photo=2337&cat=3204

Brian: You could be quite right here. The lens appears to be put togethera s you described above. I mailed the lens back yesterday to DAG for another inspection./adjustment. So far, I have paid about $350 for lens and adjustment. I hope it is worth it in the end. At the very least, there is a good chance that this lens is "rare" and not an imposter.

 

[raid]

I have an update on the Sonnar lens. DAG informed me that the shimming attached to this lens has moved somehow and that he will now use superglue to attach it to the lens mount. This should improve the focusing hopefully.