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Thread: LF pinholes?

  1. #1

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    LF pinholes?

    How do you manufacture a nice pinhole for 4x5 or 8x10? How is desired focal length accounted for (I know a pinhole doesn't have a focal length per se, but I've heard there's an optimum diameter for a given focal length).

    I'd like it to give a well defined image with only a little bit of that pinhole softness. It should have full 4x5 coverage & ultra wide angle. After losing out on a 65mm on ebay ($500 was my max, wishful thinking I might add) I've figured the only way to reasonably afford to go very wide on my LF is to make a pinhole.

    Any tips would be great. I've looked at some of the pinhole resources but they don't usually give a simple straightforward answer to these things nor indicate how to get reasonably detailed ('sharp') images.

    I'd almost buy a nice laser-drilled precise plate if needed. Where would I get one suitable for LF?
    The universe is a haunted house. -Coil
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  2. #2

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    When I grow up, I want to be a photographer.

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

  3. #3
    Jim Noel's Avatar
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    I believe Calumet still lists a set of 4 or 5 laser drilled pinholes for around $20-25.
    [FONT=Comic Sans MS]Films NOT Dead - Just getting fixed![/FONT]

  4. #4

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    Quote Originally Posted by Jim Noel View Post
    I believe Calumet still lists a set of 4 or 5 laser drilled pinholes for around $20-25.
    Do you know if there are any requirements (with regards to, for example, the thickness of the material it's drilled in) to ensure coverage for 4x5 or 8x10?
    The universe is a haunted house. -Coil
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  5. #5

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    Walter,

    there is a whole forum on pinhole cameras on Apug.

    Read it.

    tim in san jose
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  6. #6

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    Thanks tim.
    The universe is a haunted house. -Coil
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  7. #7
    Murray@uptowngallery's Avatar
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    f295.org also
    Murray

  8. #8
    Stephen Frizza's Avatar
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    A client of mine has a 20x24" pinhole camera they built themselves out of a car boot hehehehehe.

  9. #9
    Murray@uptowngallery's Avatar
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    Sounds like you have a bellows, so you make a pinhole in accordance with any of the best practices (I don't believe the laser ones are any better in practice compared to well made hand-done ones).

    You can measure it by scanning it at high res and viewing on screen, then scaling the scan resolution to the monitor resolution (SVGA is 96 dpi, not 72 as people keep saying - that was plain VGA decades ago).

    Then, regardless of what your odd size pinhole ends up being, you can set the bellows accordingly.

    Ask in the Pinhole forum here or f295 and the list of nuisance-like steps will become quite manageable.
    Or buy one as you said. There is also someone selling sets of apertures in 0.001" stainless steel for $30 on eBay.

    One person told me they were laser-drilled, but I only saw the words 'micro-drilled', which is not the same, to me.

    Hand-bored ones can have a knife edge, resulting in thinner apertures. I have seen some laser-drilled ones that had 'slag' around the hole, making it far thicker than intended.

    I'm not sure why roundness is claimed to be so important, as a square hole works too. The math model for diffraction is different for a square or slit vs a round aperture, but so what?

    The nice thing about the bellows cam is you can alter the distance and recalculate the exposure far easier than making holes exactly the size you thought you needed.
    Murray

  10. #10
    John Bartley's Avatar
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    Lee Valley tools sells numbered drill bits in a set (quite cheap) that go as small as about 0.020" (iirc). When I made my 4x5 pinhole camera, I just put a bit of brass shimstock between two pieces of thin wood, clamped tight and drilled thru'. It gave a nice clean hole in the brass and gave a fairly nice picture.

    cheers eh?

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