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  1. #11

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    Pinhole shape has a big influence. You can use that creatively (see Renner's book) or you can go for a laser-cut pinhole to optimize image quality. I can offer a contact at the University of Munich, Germany who can laser-cut pinholes into thin brass plates for you at a reasonable price. he made all of mine.[/QUOTE]

    Hi,
    I am "new" to piholes,as I have not done it in several years. And even when I was trying to do it I was nowhere near the leval of accuracy that people on this Forum are about. But it seams to me that one cannot speak of pinhole diameter and ignore thickness of the material used.
    One gentleman,on another thread, talks about hammering,filing,over and and over,until microscopic inspection shows perfect roundness and a very thin wall.
    Laser drilling will leave a wall the same thickness as the thickness of the original foil.
    Regards to all,
    Bill

  2. #12

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    Thanks for the advice guys. I'm really not too worried about the wavelength and pinhole diameter stuff. I'm just kinda curious about the physics and reasoning for doing what I'm doing, even though I'm not the best mathmatician in the world
    "Gotta little problem with personal space, and I've been pounding the Jager. My breath and behavior have been driving the patrons away" -"Whipped Cream" by Ludo


    My photography blog: http://silver-light0.blogspot.com/

  3. #13
    Romary's Avatar
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    Quote Originally Posted by RalphLambrecht View Post
    I have it somewhere and will take a look.
    Thanks Ralph.

    Just in case you do not know this one : http://inside.mines.edu/~mmyoung/PHCamera.pdf

  4. #14
    Romary's Avatar
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    Quote Originally Posted by wildbillbugman View Post
    But it seams to me that one cannot speak of pinhole diameter and ignore thickness of the material used.

    Bill

    I totally agree, I strongly believe (= I have not done any trial or calculation, which is not scientific) the thickness is one of first order parameter.

    You can find here a work (sorry in French) made by a gentleman call Claude Boutet. He concludes, what intiutively looks logical, that the thiner the material is the better it is. The only proble that a infitively thin material does not exist. And from what I can see mathematical approach usually assume an infinitively fine material.

  5. #15
    Steve Smith's Avatar
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    Quote Originally Posted by wildbillbugman View Post
    Laser drilling will leave a wall the same thickness as the thickness of the original foil.
    Depending on the laser used, it may be possible to laser etch the area around the hole so that the area local to the hole is much thinner than the rest of the material - like a lasered counter-bore.

    My laser cutter at work cannot cut metal but I do this with plastic materials.


    Steve.
    Last edited by Steve Smith; 01-05-2010 at 08:59 AM. Click to view previous post history.

  6. #16
    Steve Smith's Avatar
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    Something else has just come into my mind (always dangerous!).

    The company I work for does precision industrial screen printing. It would be possible to print an opaque layer of ink onto an optically clear material such as glass or polyester with a small opening. This would effectively make a pinhole in an 8 micron thick material (cured ink) bonded to a clear support. I might even get round to trying it one day!


    Steve.
    Last edited by Steve Smith; 01-05-2010 at 09:00 AM. Click to view previous post history.

  7. #17
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    Quote Originally Posted by Romary View Post
    I totally agree, I strongly believe (= I have not done any trial or calculation, which is not scientific) the thickness is one of first order parameter.

    You can find here a work (sorry in French) made by a gentleman call Claude Boutet. He concludes, what intiutively looks logical, that the thiner the material is the better it is. The only proble that a infitively thin material does not exist. And from what I can see mathematical approach usually assume an infinitively fine material.
    I'm sure, the thinner the better. My pinholes are laser cut into a 0.04 mm foil, which means the hole/thickness ratio is about 10:1. With this ratio, thickness has little influence. As the material gets thicker, light rays bouncing off the hole inner walls will cause optical disturbances and thickness (and the smoothness of the inner walls) become a factor. But this is not an issue if the hole diameter increases by the same factor, because the ration is important. As far as I know, there is little research on this topic.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  8. #18
    RalphLambrecht's Avatar
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    Quote Originally Posted by Steve Smith View Post
    Something else has just come into my mind (always dangerous!).

    The company I work for does precision industrial screen printing. It would be possible to print an opaque layer of ink onto an optically clear material such as glass or polyester with a small opening. This would effectively make a pinhole in an 8 micron thick material (cured ink) bonded to a clear support. I might even get round to trying it one day!


    Steve.
    This is how zone plates and photon sieves are made.
    Attached Thumbnails Attached Thumbnails Pinholes.jpg  
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  9. #19
    RalphLambrecht's Avatar
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    Quote Originally Posted by wildbillbugman View Post
    ...Laser drilling will leave a wall the same thickness as the thickness of the original foil...
    Looking at the hole under the microscope, I cannot detect that with my pinholes, but I saw it once. I returned it and got a clean replacement. Attached is a picture of my 0.25 mm pinhole.
    Attached Thumbnails Attached Thumbnails LaserCut.jpg  
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  10. #20

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    My film came in today, along with some powdered fixer and a bulb for my safelight. I'll probably mix the fixer up today and try to take a few shots tomorrow after work.

    I bought a 25 pack of 5x7 HP5+, and a bit intimidated by the size of it. The largest film I've shot so far has been 4x5, and that was back in 2007, so it's going to take me a while to get used to this large format thing. I think I can handle it, though. Hopefully I'll have some prints to show in a few days
    "Gotta little problem with personal space, and I've been pounding the Jager. My breath and behavior have been driving the patrons away" -"Whipped Cream" by Ludo


    My photography blog: http://silver-light0.blogspot.com/

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