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Thread: lefthand side of image unfocused/lense problem?

  1. #1

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    lefthand side of image unfocused/lense problem?

    I have been using this site as a valuable source of information for a long time. Now I finally have a reason to register: The following problem has been troubling me for a while and I hope someone can help me:

    Last month I exchanged my Sinar to a Linhof Thechnikardan and had to get my Rodenstock Grandagon-N 75/4.5 changed from a Sinar to a Linhof lenseboard. The guy in the shop mounted it to a Toyo-View lenseboard instead, claiming that it should still work. It sits quite loosly in the camera, but I thought I will give it a try.

    Last week I used the camera with this lense for the first time and I have noticed that the lefthand side of the image is somewhat unfocused.
    Since then I have been doing numerous testshots (of a carpet hanging flat on a wall)
    - with 10mm shift to the left
    - with 0mm shift
    - with 10mm shift to the right

    The lefthand side of the image is always blurry (a strip of about 2cms) !

    The guy in the shop claims I am too close to the edge of the image circle. But I doubt that! I have been doing some wild shifting with that lense when I still used the Sinar, It gave me black corners every now and then but never any blurriness!

    Do I have a
    camera problem
    a problem with the lenseboard
    or a problem with depth of field (aperture 22.5 for a flat, perpendicular object)????

    Please help, any comment much appreciated.

    Thanks,

    K. Mayer

  2. #2

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    Re: lefthand side of image unfocused/lense problem?

    Sounds like an alignment issue, but without being able to see the camera, my thought is a shot in the dark.
    When I grow up, I want to be a photographer.

    http://www.walterpcalahan.com/Photography/index.html

  3. #3
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    Re: lefthand side of image unfocused/lense problem?

    Did he remove the little indexing pin on the back if the shutter before mounting it on the lens board?

    If not, the lens might be mounted with a slight tilt.

    Some lens boards have a recessed area where that pin fits. The new lens board might not have one. Removing the pin will solve the problem.

  4. #4

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    Re: lefthand side of image unfocused/lense problem?

    my guess is that the ground glass might not be shimmed correctly or is somehow out of alignment. If the image is in focus at all points on the ground glass and then it doesnt translate to the final image on film- then the positioning of the film holder would appear to be different from the focussed image on the glass. I would look into that first with a reputable repair facility. the second thing I would look at is the loosely mounted lens- that's not a good thing either.

  5. #5

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    Re: lefthand side of image unfocused/lense problem?

    I use this lens all the time. It is very sharp and has decent coverage for a 75mm, plenty for 10mm of shift/rise. A small amount of swing or tilt induced by miss mounting or the lens board not sitting snugly would not produce blur at f22.5, in this type of test. Are we talking about blur or slight soft focus?

    Does the same side blur/soft focus when you apply tilt/swing that would normally bring that area into sharper focus? If it remains blurred you might have some type of internal problem.

    If it's not the pin issue Gem mentioned, perhaps one of the lens elements is cross threaded, most likely the rear element as you do not remove the front element to change a lens board. You can test this very easily, just unscrew the rear element slightly and see if it turns smoothly. It should be tight at first and then turn very easily and smoothly (righty tighty - lefty loosey). If its not cross threaded then you need to do further testing or send it to SK Grimes.
    Will Wilson
    www.willwilson.com

  6. #6
    Whatever David A. Goldfarb's Avatar
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    Re: lefthand side of image unfocused/lense problem?

    Alignment is more critical with wide lenses. Do you have other lenses you can test on this camera? Have you checked the alignment of the camera? If it's a Technika-style Toyo lensboard, it shouldn't be so far out of alignment as to cause this sort of problem and shouldn't fit loosely, though it might not be quite as tight a fit as a Linhof board.

    The 75/4.5 Grandagon-N has plenty of coverage for 4x5". I use it on 6x17cm.

    Another possibility--are your filmholders seated properly in the back? If not, that would cause the problem you are describing, and it would be very obvious with any lens.

  7. #7

    Re: lefthand side of image unfocused/lense problem?

    The first question that comes to my mind: Is the image sharp when you view it on the ground glass with a loupe? If it's sharp on the ground glass but fuzzy on the film, you've got a misalignment between the ground glass and the film. Your ground glass may be in the wrong place (shimmed improperly, for example), or your film holder(s) may not be seating properly in the camera back.

    One other possibility: Are you sure that the problem is that the edge is fuzzy, and not that it's exposed differently than the rest of the sheet? I ask this only because I thought I had an edge that was fuzzy on a negative once when I first glanced at it, but when I actually stopped and looked at it I realized that the edge was slightly underexposed. It's a long shot, but worth checking if nothing else is working out.

    Best of luck.

  8. #8

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    Re: lefthand side of image unfocused/lense problem?

    thanks for the answers, it gives me some things to try out.
    I did also suspect that it much be some kind of alignment problem.

    To answer some of the questions:
    it is in fact more of a soft focus rather than a blur
    I have tried with other lenses (115, 250) and don't have the same problem
    the lensboard can be moved a 1,2 millimeters each way in line with the camera
    the image is also out of focus on the ground glass

    Could I have an alignment problem that is always there but only shows when I use the wideangle but not with the other lenses?

  9. #9
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    Re: lefthand side of image unfocused/lense problem?

    It's sounding more and more like the lens was mounted without removing the tiny index pin that screws into the back of the shutter. I have a few Sinar boards that have a recess for the pin. I have also used Toyo boards in the past that did not have a recess.

    You stated that the lens worked fine when it was mounted on your former Sinar Lens board.

    If a shutter is mounted with no recess for the pin, it will tighten down on the lensboard but the shutter will be slightly tilted. The problem will show up as you have described- a mis-alignment on the GG- unable to focus the entire image sharply.

    Have the tech un-mount the shutter and check to see if the index pin is still there.

  10. #10

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    Re: lefthand side of image unfocused/lense problem?

    As David mentioned before alignment is more critical with wide lenses. So you can swing the back and look if the blur vanishes. If so back and front standard are not parallel in the zero position and the camera has to be aligned in the factory.

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