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Thread: Lens flare? Bright corners

  1. #1

    Lens flare? Bright corners

    Hi,
    I've got a problem with bright corners on negatives and I'd like to find out what's causing it. I'm pretty sure, but not absolutely certain that there should've been no direct sunlight falling on the lens taking any of these pictures, and especially the third one I clearly recall the sun being behind the camera. Here are links to the pictures.
    Picture 1
    Picture 2
    Picture 3
    I actually took two nearly identical pictures like the third one, the second with filtration, and both show the same pattern or bright corners, the top right corner being especially bright. Also the whole right edge in #1 and #2 is clearly brighter. I'd like to know whether this is just bad shading or something else. If it should likely be bad shading, the lens has to be real picky.
    It's a Schneider-Kreuznach Tele-Xenar 1:5,5 270mm objective with a compur shutter. I checked the lens serial on the manufacturer's website and it's from the '50s and has a red triangle on it, which I was told means coated lenses. With all of the images above, unlike with vignetting, I couldn't see the effect on ground glass, but maybe I just wasn't looking carefully enough. The deal I've got with the very kind guy I purchased two objectives from was that he knew one of the six I chose from had some kind of problem, but he couldn't recall which it was and could it be fixed. So can this lens be fixed and for about how much? The deal went that I'd be able to change the objectives for the others he had, if there were problems. I'd be able to change this for a Tele-Xenar 5,5/360mm for little extra cost.Thanks a bunch for all answers!

  2. #2

    Join Date
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    Lens flare? Bright corners

    Um, er, ah, a negative with lighter corners than center received less exposure in the corners than in the center. That's vignetting, not flare, the lens doesn't cover the format.

  3. #3

    Lens flare? Bright corners

    That's why I included the pictures. Forgot to mention they're taken of negatives though. They're denser at the corners, so brighter as in more light passed onto the negative near edges.

  4. #4

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    Lens flare? Bright corners

    Looks like light leak in the camera. Either a problem with a detachable bellows, or light leak around the lens or lens board. Doesn't look like film holder fogging or fogging in the box.

  5. #5
    Abuser of God's Sunlight
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    Lens flare? Bright corners

    does this problem only happen with that one lens? it doesn't look like flare to me.

  6. #6
    Resident Heretic Bruce Watson's Avatar
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    Lens flare? Bright corners

    I'm with Graham. Looks like light leaks around where the bellows attaches to the rear standard.

    Bruce Watson

  7. #7

    Join Date
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    Lens flare? Bright corners

    This doesn't look at all like lens flare to me. In some of these it doesn't even look like you were exposing in direct sun. I think Bruce and Graham have given good suggestions for where to look first. Also, if they're right, that would explain why you don't see the issue on the ground glass, especially if you are covering the problem with the dark cloth when composing. Even a very dim leak (which you couldn't see when composing) can expose the film over the time the dark slide is removed. Put a new sheet of film in the camera in the sun with this lens on it, pull the slide so that the film is open to the supposedly dark inside of the camera for a minute or two, DON'T TAKE A PICTURE, develop it and see if you get density. My hunch is you will. That would eliminate lens flair. Try the same thing with a different lens on a different lens board. If it doesn't happen that time, look at lens board fit, possible pin holes, etc. that are peculiar to this lens and board.

  8. #8

    Lens flare? Bright corners

    I just checked and I can't see a leak, and yet the leaks should be quite apparent since the negative's in place without a darkslide only so long and gets exposed around the edges like that right? It's a tele objective, and the three pictures above have been shot focuse almost at infinity, which means the bellows are less extended than they are in the position you fold the camera in. The camera's new and I checked it for light leaks when I got it and just now, though with a poorer test setup - nothing. I checked with the lens attached and there's no light coming through at the lensboard that I could see. Could this be due to a film holder put in poorly? I tried with a holder and at least this one didn't leak when viewed through the front standard, so maybe I've just put them in poorly? How likely is that, if you suppose you take some care doing it?
    Here're three pictures I've taken with the other objective I've got, a 90mm Angulon. At infinity the bellows are quite compressed, so you wouldn't necessarily see the leak, but these three were taken close to the subject, bellows almost fully extended. You'd suppose if there was a light leak near the rear standard, it would be very evident here, right? The first of these (no.4) has a clearly similar effect with the first three, but on the latter two I would disagree, as the digital camera I took the pictures with has some fall off around the edges too, and if you compare these to the first three, the pattern in the first three is rather particular (especially the top right corner of the negatives).picture 4&nbsp&nbsppicture 5&nbsp&nbsppicture 6
    Especially taking the particular pattern of the leaks or whatever they are into account, you'd think this has to do with the particular objective/lensboard, right? The first three pictures were taken with the lens fully stopped down (f/32) if that may count for anything.

  9. #9

    Lens flare? Bright corners

    Problem found, thanks for the suggestions, I'm not sure if I would've found it without them.
    It's indeed a light leak at the lensboard . I didn't know it would be that elusive; I actually had to let my eyes adapt a while to see that it leaks very slightly basically aroung the whole shutter. The next thing is I need to figure out how to fix it. Generally, can you just mount the lens better on the same lensboard, or does it take a more snug fit lensboard to fix these leaks?

  10. #10

    Lens flare? Bright corners

    Check to see that your lens does not have one of those little grub screws for preventing twisting of the shutter on the board. If it does, remove the screw, tighten up the retaining ring and you should be all set.

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