Rollei 2.8D question regarding taking lens assembly

Discussion in 'Medium Format Cameras and Accessories' started by hmzimelka, May 1, 2013.

  1. hmzimelka

    hmzimelka Member

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    Hi all.

    I really hope someone here can help me figure something out...

    I have a Rolleiflex 2.8D, with a Schneider Xenotar 2.8/80 lens.
    I'm experiencing a fair share of inward running field curvature from the centre to the outside of my frame.

    My 2.8D is not pristine, and it had some work done on it...
    Part of my question is, should there be a thin flat washer behind the front lens assembly. ie the part one can screw off the front to access the shutter blades.
    I'm talking a very thin washer, if thats even the right term for it.

    I haven't seen it on my other Rollei, be it a 3.5 Tessar lens. My friend, who fiddles with Rolleis, doesn't recall there being one either.
    Taking the thing out doesn't really make a difference.

    Example of the washer bellow...
    photo.JPG

    I have yet to develop the film where I have screwed the front lens out a fraction ( about 0,5mm or less), just to see if there is any difference in the curvature.

    I have originally calibrated my centre focus using a split screen and high magnifying loupe to get the centre right, which is sharp, no doubt about it.... however, the edges always focus in front of where the centre is focused.

    Please visit a folder (LINK) on my ftp server, where I have two 1600ppi scans from my Imacon showing the effects.
    Both images are focused behind infinity, and images were shot at f/5.6.

    I live in Namibia now, a place even more backwards than South Africa, which is where I moved from (Cape Town more specifically). There are no decent or reputable repair shops around, and South Africa is filled with plenty of camera butchers. I don't really want to send my camera in. It's just not worth it. I'de rather try and find another Rollei at some point...

    Can anyone confirm what the deal is with the washer, and whether it belongs there or not, and if it does belong, what the appropriate thickness may be.
    The repair guy who cleaned and serviced my shutter a few years back, admitted to having lost the original ring, and replaced it with a new one. Whether or not the thickness correlates or not is my concern, and whether it is responsible for this curvature of field...

    Anyways. Thanks in advance for the help.
     
  2. Dan Daniel

    Dan Daniel Subscriber

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    I've not seen such a washer on my 2.8C Xenotar. Or behind a 2.8A Tessar, or behind a variety of 3.5 Tessars and Xenars. No washer behind the front lens group on any Minolta Autocords or YashicaMats, either. Or Zeiss Ikonta Tessars.

    Have you simply removed the washer, screwed the front element back in as far as it will go, and then made shots? Every lens I have ever disassembled that goes on a leaf shutter like a Synchro-Compur has the front and back blocks simply screw onto the shutter body without any washers or spacers. Proper lens spacing is designed in to the mounting, not adjusted by washers or such.

    That washer looks like one that would go behind the shutter. I'd have to dig out some notes, but I think that there is usually a brass one to the front side of the lens board and a blued steel one to the back side of the lens board captured by the rear retaining ring/light shield (you can see this as a ~15mm(?) tall tube inside the camera).

    There are repair people out there who would probably give you a simple yes or no answer with some better photos and explanations of where you found the washer. Most of the ones I have dealt with are helpful people who would understand your location and problems with shipping and might provide a simple yes/no answer as to whether they have ever seen such a washer in the position you describe.
     
    Last edited by a moderator: May 2, 2013
  3. hmzimelka

    hmzimelka Member

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    Thank you Dan.

    Your reply already helps a lot. I have removed the washer, and have tightened up the front element.
    I have taken test shots, which I hope will be good enough to see any variations in curvature. Some shots done with the lens rotated out a fraction, and some with the front element screwed in completely without a washer. I also tried to compensate for the shift in focus due to the adjustments, so I'm hoping I did it correctly, and within usable margins. Time will tell.

    As far as I know, the camera has not had the lens assembly completely disassembled. However, I'm not skilled enough to disassemble the Rollei and put it back together, so I couldn't tell you about the state of washers behind the shutter.

    The scans will hopefully settle my curiosity as to how the position of the front element affects the curvature of field, if at all... If I cannot see any differences, then I need to either live with the curvature, or find myself another Rollei, which is near impossible down here... Its just a complete pain in the but to deal with the curvature for landscape shooting, especially if the problem isn't largely corrected for by stopping down to f/8.
     
  4. ic-racer

    ic-racer Member

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    My 20 year experience with a 2.8f leads me to the following suggestions:
    Many 120 rollfilm cameras don't always hold the film flat in the middle, but the edges are held in place. That slight bulge in the middle makes the center focus farther away than the edges. This is probably what you are experiencing.
    Indeed, a shim on the front cell will change curvature by making the perimeter of the field focus farther away and having not much effect on the rays near the center of the optical path. However, without using the Rolleiflex glass plate accessory to hold the film flat, your results of testing lens spacing will be subject to errors.

    I'd just put the shim back where you found it.
     
  5. Dan Daniel

    Dan Daniel Subscriber

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    The washers behind the shutter are not critical to the functioning of the camera. As long as the film wind and shutter cocking works, I wouldn't worry. If any of the washers are shims for lens infinity setting, there are other ways to achieve this. Your primary issue is to get rid of the softness in the center of your images. The Xenotar should NOT be giving you images like your links.

    Take out the washer and tighten the front lens group into place, finger tight is fine. No 'fraction' out or such. 0.5mm is not a small amount in optical systems!! Rollei's spec for alignment of the lens board to the film plane is 0.05mm (1/20thmm, one-half of one-tenth of a millimeter, .002 inch) maximum difference between the four corners of the film plane, and it is this large because you are dealing with depth of field and such. And this large a number assumes a precise optical/shutter assembly, which comes about from machine work, not random washers and shims.

    Once you get the shutter block properly assembled and giving you relatively flat focus plane, correcting for infinity focus isn't hard, and getting the viewing and taking lens in alignment isn't hard. But none of that is worth much if the lens is giving you poor images.
     
  6. hmzimelka

    hmzimelka Member

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    Ic-racer, thank you for your comment.

    The issue of film not lying flat had crossed my mind. However, the Rollei infrared film, and also some of the other Rollei films, are films that have the least curl I know of. Both vertical and horizontal. The horizontal curl is often such that the emulsion would, if anything, tend to curl in the opposite direction to the lens, pushing the centre into the backing paper. I've had a warping issue once with Tri-X, but thats the only time I observed the effects of in-camera film warping. My other Rollei doesn't display any strange or strong filed curvature issues. Somehow, I tend to think it can't just be the film. I have shot many different brands, PET or triacetate, thick and thin emulsions... on the 2.8D, the behaviour has always been the same.

    Regarding what you said about the front element position; Do I understand you correctly, that moving the element away from the shutter, that the perimeter will focus further towards infinity while the centre will largely be unchanged? ... In my case, mitigating the curvature I'm experiencing? I don't understand enough about optics to imagine the result of moving one element or group of a lens.
     
  7. TheFlyingCamera

    TheFlyingCamera Membership Council

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    I'm wondering if one of your lens elements (or groups) is installed incorrectly. Look up lens diagrams and check that everything is installed in the proper order, in the proper alignment. You mentioned camera butchers in SA - I wonder if one of them got their hands on it in the past and switched something around that they shouldn't have.
     
  8. hmzimelka

    hmzimelka Member

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    Dan, the viewing lens is fairly well calibrated to the taking lens, in that I get the centre sharp when I need to. The examples were simply deliberately back focused to emphasise the relation of the centre to the edges.

    I have removed and stored the thin washer/shim from the lens. The front element is seated securely. I can't draw any conclusions from my test image, and I will have to shoot a few rolls and see. By the test image HERE,
    [​IMG]
    It seems it may be slightly better now, or I may be imagining things. Differences between centre and edges are still visible at f/5.6, and the differences appear to be symmetrical.
    (the mountain's edge is further away on the right than the focused centre) The skew light pole is about a meter behind the white wall on the left.
     
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  9. hmzimelka

    hmzimelka Member

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    I'm afraid I'm not sure how to determine if the order is correct or not, as I cannot disassemble my Rollei without fearing that I may never be able to put it back together again.

    Under correction, the camera has only had it's focus screen modified, which was done by someone with two left hands, and I had it's shutter serviced. This focus screen installation was probably a DIY attempt by the previous owner. Besides the focus screen and the repair chap who cleaned the shutter, I don't think the lens assembly has seen any disassembly. No paper trail to back that up, so anything is possible :sad:
     
  10. TheFlyingCamera

    TheFlyingCamera Membership Council

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    The lens cells would have to be removed to access the shutter for servicing, so it is possible they were put in wrong. If you're that concerned about it, I'd ship it off to someone in the US or the EU to have it properly serviced (even with the shipping cost, it will be worth doing, as the camera seems to otherwise be functioning). I have a 2.8E that I bought in well-worn condition that needed a major overhaul. The servicing cost me almost $400 USD, but now I have a camera that will last me another 20 years. When you spread that cost out over the life of the camera, it comes down to pennies a day. Very economical.
     
  11. Dan Daniel

    Dan Daniel Subscriber

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    A real cleaning of a shutter involves removing it from the lens board. This allows for thorough cleaning and maintenance.

    Typical removal ofthe lens blocks would involve simply unscrewing the front block en masse and the rear block masse. There is no breakdown of the front or back lens groups needed. Of course this doesn't mean that it didn't happen. Sometimes the front retaining ring, for example, is actually retaining the front lens element, not the front lens block.

    I am not certain about your sample image above- so many sloping surfaces, hard to know what is what. this is where the infamous brick wall shows it usefulness. My first impression is that it doesn't have the curved focal plane of previous shots you showed?

    My thinking is that whoever worked on the shutter removed it from the lens board. this means undoing the retaining ring/tube on the back of the lens, inside the film chamber. Underneath this ring is a washer that look amazingly like the one you show. I bet whoever put the camera back together forget where that washer went, or simply had it left over when he thought he was done. So he put it on the first place it fit- the back of the front lens group. The washer isn't serving any functional purpose on the back of the lens board, it's just your standard 'best practices' approach to tightening down assemblies.

    Try for beter test shots. Try with and without the washer. Let's hope it was what I think, because you will be done shortly if so. But then again, other things such as people have mentioned might be the cause.

    Oh, I haven't even given much attention to the back lens block. You can take a small screwdriver and very lightly see if it can be spun out by putting the screwdriver tip in one of the retaining ring slots. And see if it can be tightened down any. Be very very VERY VERY careful here- metal and glass are a nasty combination if you slip. There are other ways to check this- I save wooden chopsticks from takeout to whittle safer tools for things like this. All you are doing is checking for looseness.
     
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  12. ic-racer

    ic-racer Member

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    My error it is the other way around, too late to change my post above.
    In terms of film bulge, on 120 SLRs you can check this with "B" and press the tip of a pencil on the film to see if it indents. You know the film can never bulge backwards behind the pressure plate unless your pressure plate is bent. So even if the film has a curve to it, when it gets squeezed between the film gate and the pressure plate it can only bulge in one direction...toward the lens. I will say that I have not had a camera that did it consistently with all films, so you may have a lens issue as others have pointed out.
     
  13. jochen

    jochen Member

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    Hello,
    the Planar/Xenotar was a remarkable improvement of field curvature against the Planar/Xenar. The problem of 120-film of not being flat in the camera is as old as this film. Carl Zeiss made investigations of this problem and found that the best flatness is immediately after transport. The film remains flat for about 15 minutes and than the curvature comes back. So it is best to transport only immediately before the exposure is made. The Rollei service had special non flat matted screens for testing the focus into which the average curvature of film had been grounded. The Rollei service also had exploded views of the lenses and how to center and adjust them. In this views you could see whether and where there should be a washer or not. Testing of focus was made with a so called autocollimator and they had very close specifications for measurement of the alignment of the front plate and the focus.
    The best would be to give the camera to a real expert with appropriate equipment.
     
  14. Richard S. (rich815)

    Richard S. (rich815) Subscriber

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    Did you mean Tessar/Xenar?
     
  15. elekm

    elekm Member

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    I think that "washer" was a spacer and probably used to set/achieve infinity focus.

    Depending on the construction of the lens, there might not be a free-standing middle element or group. However, when a middle lens element is placed in the camera backward, the impact on image quality is very obvious. I don't think that is your issue here.

    I have some theories, but without seeing the camera, it's difficult to say whether they might apply to your camera.
     
  16. sangetsu

    sangetsu Member

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    I have never seen a spacer used to calibrate the lens on a Rolleiflex camera. The washer shown does resemble the washer used between the shutter and the front standard, but the aperture assembly would not work properly and the shutter assembly would be loose if the washer were ommitted. The Xenotar lens does not have many elements, and installing them in the wrong order or in the wrong direction is highly unlikely. Ommitting a spacer between elements would either allow the unspaced element to rattle around, or break when the retaining ring was screwed on. Most likely the front and rear groups are mismatched, and the rear half is from a Planar.
     
  17. Ian Grant

    Ian Grant Subscriber

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    Maybe the spacer was added to optimise the lens for close focussing, seem fine without it. You may also be expecting too much of f5.6

    I wouldn't draw too many conclusions from those images. It needs testing more objectively.

    Ian
     
  18. Dan Daniel

    Dan Daniel Subscriber

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    There is also another washer behind the lens board, between the lens board and the shutter retaining ring/light baffle piece. This is where I think the washer came from. It being left out won't affect any mechanical systems.
     
  19. jochen

    jochen Member

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    Sorry, off course I ment the former used 4-lens types Tessar and Xenar. If you increase the distance between the front lens group and the rear lens group by inserting a washer, I think besides poorer image quality and increased aberrations you will get a change in the reproduction scale. It is something like a front lens focussing.
     
  20. Ian Grant

    Ian Grant Subscriber

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    That's correct. More importantly that's introduces distortion when a lens is then used at or near infinity.

    One of the long CZJ Tessars has quite a large spacer like a small extension tube for close up work where its used as a process lens, this needs to be removed for normal work. G-clarons are also optimised this way.

    Ian
     
  21. hmzimelka

    hmzimelka Member

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    Thank you for all the replies. I have been away for the weekend, so i haven't had the chance to check in and reply!


    Thank you Dan. I'll definitely go for better test shots. During the week, I don't have much time to do test shots in good light. I'll have to see what I can do over one weekend. It may be that the curvature is better. The mountain slope, which is sharp in the centre, is a good 100 meters away from the camera. The wall can't be more than 25 or 30 meters away. Even that skew light pole is sharper at its base than at the top. Will try and find a flatter target.

    I'll check the rear lens group when I can. At the moment, I have a roll of film in the camera...



    OK, thanks.


    Interesting. Thanks. It has always been my habit to advance the transport prior to taking my image. Seems like a good habit :smile:
    It will be best to give the camera to an expert, however, it's not the easiest option for me right now... I'll do this when I have a friend going to and coming from the USA, but first I'de need to get my other Rollei working (Automat MX EVS). Seems she has gotten herself a new problem. The film advance doesn't stop at the frame numbers when a film is in the camera.



    Interesting. Hopefully I can have it looked at by a qualified repair man. Perhaps I could simply buy a new Rollei. A 2.8E or something reasonably priced.



    Yeah, definitely needs more testing. However, I have seen on some of my images, that even at f/11 or f/16, that the problem can still be seen, but to a lesser degree of course.
     
  22. TheFlyingCamera

    TheFlyingCamera Membership Council

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    A quick fix for the film advance problem on your Automat- put a single layer of cellophane tape on the sensor roller (the one you thread the paper leader under when loading the camera). That should solve it.
     
  23. hmzimelka

    hmzimelka Member

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    Thanks. I gave that a try, but it didn't work. That click sound the camera makes, which sounds when the film starts under the backing paper, is heard even without the added tape.
    I tried normal thin tape, and also a thicker gaffer tape. The numbers roll through without stopping. Wonder what the problem is. Everything happens in threes... what is next? :tongue:
     
  24. hmzimelka

    hmzimelka Member

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    So, for those interested, here is the update...

    I found some RPX 400 in the fridge, which, in my opinion, is not a nice film when Rodinal is the only developer around.
    So, the only use it has for me is test film...

    I screwed the front taking lens group outward until the black ring was aligned with the silver ring sitting around it. This is about 0,55mm outward from it's most tightened position.
    I took some shots with bracketed focus to compensate for the change in focus.

    I then shot an image of the same composition but with the front group screwed all the way in.

    Surprisingly, the images taken with the front group screwed outward, showed the best results. The far edges still focused inward compared to the centre, but not nearly as much as with the front group screwed in.

    Bellow are the links to the images. Please note, the tree is not the focus point. I focused for the hills, at infinity. Shot at f/3.5

    Front group screwed out and Front group screwed in
     
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