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  1. #11
    Joe VanCleave's Avatar
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    I have some experience with this sort of thing, as I've made a 4x5 wooden pinhole camera. It appears to me that the rear walls of the box around the sides of the film holder are too shallow, permitting too much light to leak into the camera. This is evident in the light leak along the bottom of the portrait-oriented image corresponding to the top of the camera (images in cameras are inverted at the film plane), where you'd expect sunlight most easily to strike that portion of the camera. In my camera design I made a deeper flange, with walls that extended beyond the rear of the film holder, helping to protect the light trap against leaks.

    As a fix, you could make L-shaped pieces from thick black scrap book paper, taped together with black gaffer's tape, secured along the edges of the camera so as to fold down behind the film holder. Holes in two sides would permit the knobs to still be attached to the camera.

    Also, I've gotten into the habit of using a dark cloth (or old black shirt) over the camera when pulling the dark slide, as an added insurance.

    For the third image from the left, it appears the darkening of the sky may be from improper agitation (or too much agitation in too small of a developing tray?)

    And the last image shows mottling in the sky that could be from either improper agitation or too short of a developing time.

    Keep at it, I look forward to more images as you make progress. This can be fun, and addictive.

    ~Joe

  2. #12

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    Feb 2009
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    Quote Originally Posted by Joe VanCleave View Post
    It appears to me that the rear walls of the box around the sides of the film holder are too shallow, permitting too much light to leak into the camera.~Joe
    Thanks, Joe. True, the rabbet cut in the inside edge of the rear of the body is only about 1/4" deep, which is about half the thickness of the film holder, and therein may lie the problem. I have a decently equipped shop, and could easily cut it deeper with a small router to allow the film holder to fit approximately flush with the back of the camera body. That would reduce the focal length from 79mm to around 72mm, which should be of little consequence since it would just make it a bit wider angle camera than it is now.

    However, since the current focal length is a little too wide for my taste anyway, I might just build a simple extension (maybe 75mm) for the back that would fit tightly in place of the film holder, a la the Zero Images 4x5. That would give me the option of either 72mm or 150mm, and narrow the field of view more to my liking. At 150mm I should be at around f/295 with the camera's current 0.020" pinhole. Even with Plus-X that would still keep most exposures below 2 minutes, and I suppose I also could go to 400 film if necessary for lower light situations.

  3. #13

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    Feb 2009
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    Well, I think I've met the enemy, and as usual it is me. I dropped a small high-intensity LED lamp inside the camera, inserted a film holder, turned out the darkroom lights and took a careful look. I should have done this when I first received the camera, but of course I was in a hurry to try it out. The (or at least a) problem was immediately apparent, namely operator error. I've been inserting the FH in all the way until it bottoms out, then tightening down the hold-down nuts. That seemed like the right way to ensure a solid fit and repeatable framing. But not so fast, my friend... That method caused the plastic ridge across the top of the FH (which is supposed to act as a locating ridge and fit exactly into a narrow groove across the top) to go PAST its mating groove by about 1/8". Since the locating ridge on the FH wasn't dropping into the groove for it, the ridge was actually holding the FH slightly away from a light-tight fit at the top.

    After further careful inspection I also found that one of the plastic FH's I had set aside to use for this camera to be slightly warped. Not much, just a few thousandths, but then it doesn't take much. I don't think that was THE problem because the light leak happened with several different film holders, but since I have plenty of FH's that one has been trashed.

    Will shoot and develop a few today and with luck will report the problem's been solved.

    ====================================

    Ok, test complete, before and after images attached. I made no mods to the camera, just properly seated the film holder this time. I see I also managed to get my shadow in the foreground, too. Sorry to have taken up bandwidth with this silly problem, but I do appreciate the thoughts and help on solving it.
    Attached Thumbnails Attached Thumbnails Gazebo2.jpg   fp4+ 2-sec.jpg  
    Last edited by picker77; 01-12-2011 at 01:44 PM. Click to view previous post history.

  4. #14
    Sirius Glass's Avatar
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    Quote Originally Posted by picker77 View Post
    The (or at least a) problem was immediately apparent, namely operator error.
    Ah, the old Operator Assisted Failure [OAF]. As in the oaf did this or the oaf did that.

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  5. #15
    DWThomas's Avatar
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    Glad you got it sorted out, and that you reported back. It's always good to see these diagnoses confirmed.

  6. #16

    Join Date
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    Quote Originally Posted by Sirius Glass View Post
    Ah, the old Operator Assisted Failure [OAF]. As in the oaf did this or the oaf did that.
    Steve
    Yeah, can't understand it... that's the first time in 50 years of fooling around with cameras that I've had an operator error. Not!

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