Whats wrong with my pinhole?

Discussion in 'Exposure Discussion' started by starvingjack, Jun 12, 2012.

  1. starvingjack

    starvingjack Member

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    Could anyone please tell me whats wrong with my pinhole camera?
    It seems that I cannot expose for the full image.
    :sad:

    pinhole1.jpg

    pinhole2.jpg
     
  2. daleeman

    daleeman Subscriber

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    Post some photos of your camera and some details. Is this a new camera you made, never used before, just became a troubled camera after years of service?

    On thought is the hole is not right, miss shapped but I thing more clues are needed.

    Maybe move this to the pinhole threads.
     
  3. SMBooth

    SMBooth Member

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    Mechanical vignetting, make the hole the pinhole sits behind bigger diameter. Yes post a photo of camera.
     
  4. jeffreyg

    jeffreyg Subscriber

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    I just started using an Ilford Titan and love it. So far the results have been great. I'm not up on the math relating to the relation of the size of the hole and the distance to the film plane but that information is available. From the examples it also looks like the pinhole might not have sharp edges.

    http://www.jeffreyglasser.com/
     
  5. DWThomas

    DWThomas Subscriber

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    Yes, more details are needed. Dimensions such as pinhole to film distance and film size, etc. Is the pinhole in paper-thin material? I've never tried a pinhole in a thick sheet, but those look like what I might expect if I drilled a small hole through a thick piece of stock.

    It is surprising how easily vignetting can occur, especially if the camera is set up for a wide angle of view.

    (Been there, done that, etc.)
     
  6. Toffle

    Toffle Member

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    What's amazing is that the Zero Image 45 can cover 4x5 at 25mm without vignetting. I forget the specifics of the angle of view, but it is quite extreme. That is quite a feat of design. I found out the hard way in trying to mimic their design.

    Cheers,
    Tom
     
  7. starvingjack

    starvingjack Member

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    Thank you all for your help. I shall post more images of the camera tml.
    Yes it is hand made. I have a small piece of wood (5mm thick, laser cut a hole), and a foil with a pinhole right behind the wood.
    As far as i can tell, the hole in the wood piece and the foil is the same size.
     
  8. E. von Hoegh

    E. von Hoegh Member

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    There's your problem. It isn't a pinhole, it's a smallbore tunnel.

    Cut a hole the size of a quarter, put the foil pinhole behind - or in front - of that.
     
  9. DWThomas

    DWThomas Subscriber

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    I agree with E. van Hoegh. (It looks like my original guess was on the right track.)

    The ideal pinhole is a perfectly round hole in an infinitesimally thin opaque sheet; e.g., a knife edge around the hole. All the supporting structure needs to be totally out of the light path.

    I have more than you may want to see on line of the 4x5 'box camera' I made last year. The holes the pinhole plate mounts against were at least 3/8 of an inch in diameter. In addition, the surfaces away from the pinhole plate were counter bored at about 7/8 inch diameter to about half the thickness of the 1/4 inch plywood pieces. That camera uses a dimple-and-sand pinhole in 0.001 inch brass shim stock (and may be the best I've made so far).
     
  10. Ronald Moravec

    Ronald Moravec Member

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    I believe Pinhole Resource sells remade pin on brass sheets.

    I made mine from my 4x5Zone VI camera so I had full view camera movements. I have to site along side and top as the image can not be viewed on glass.