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  1. #1

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    Pinhole size recomemndation

    Hello all.

    I am preparing to try some pinhole work on my 8x10 and I'm not sure what size to start with. I have the option of the following plate/focal length to begin: 16mm, 35mm, 48mm, 73mm, 88mm, 118mm, 151mm, 184mm, 233mm, 288mm, 352mm & 473mm.

    As I mentioned I will be using this primarily on 8x10 and 5x7 and I know nothing yet as to coverage (if an issue) with pinhole. I will also be using this landscape and some still life.

    Recommendations? Pinhole is new to me so I have much to learn.

    Thanks in advance.


    Tim
    www.ScottPhoto.co

  2. #2

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    You could try Mr. Pinhole.just do a google search under that name. Which has a calculator that will help with what size
    I hole you will need. Also I would think that in 8x10 or5x7 a focal length less that 125mm would be as wide as you would want to go. Good luck.

  3. #3
    DWThomas's Avatar
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    Here is my 8x10 pinhole camera, with various parameters listed. I did a little work with paper negatives back at the end of April for WPPD, and picked up some 8x10 Green Xray film early this summer, but have been too busy with other stuff to experiment further.

    The pinhole constant (1.65) and f/22 multiplier are related to the use of Pinhole Designer, a Windoze based utility. The pinhole constant is a magic input typically ranging from 1.4 to 1.9 or so. The "f/22 exp multiplier" is used for metering. You read the exposure time for f/22 and then multiply it by that multiplier to get the actual exposure at the tiny pinhole aperture. (There can still be issues of reciprocity failure which may need to be dealt with.)

  4. #4
    SMBooth's Avatar
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    For a first up 810 I would build something in the 140 - 200mm range, and use a .5mm pinhole. Maybe .4 at the 140mm end. For your second camera, you will build a second one I would play around with 80-100mm range. You won't go wrong following DWT post above.

  5. #5

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    The formula I use is D= .0015 SQRT(F) where D is the diameter of the pinhole in inches and F is the focal distance in mm. For a 100mm focal distance the SQRT of 100 is 10, and the pinhole diameter is .015 inches. I use an old set of spark plug gap gauges (the wore kind) to measure the pinholes. If I get below .015 I use fine wires as the gauge.

    If you get below a focal distance of 100mm you will probably see some fall off at the edges of your image with the 8x10, not so much at 5x7.

  6. #6

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    Thanks all! Super helpful. Looks like I'm starting with a 151mm and 288mm. Almost time to play.

    Tim
    www.ScottPhoto.co


    Tim
    www.ScottPhoto.co



 

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