another pinhole size question!

Discussion in 'Pinhole Photography' started by youwattom, Feb 14, 2010.

  1. youwattom

    youwattom Member

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    what tool do you measure the pinhole diameter with?
    the gap between the pinhole and the film is?
    could you use colour filters with a pinhole?
    I struggle to understand f/stops any simple description?
    Sorry for my simpleness.
    1.23mm= 1.23mm or 1.23cm?!
     
  2. FM2N

    FM2N Member

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    Pinhole diameter is based on focal length of camera. The finished pinhole can be measured using a flatbed scanner or buying a pre-made pinhole for your camera focal length.
    Gap between pinhole and film is called the focal length.
    Not sure about color filters with pinhole photo's but I have used B&W filters with my pinhole cameras and they work.
    F/stop is pinhole size divided by focal length or visa versa.
    1.23mm is 1.23mm
    1.23cm is 12mm give or take.
    Here is a great link. The program can be downloaded and it will tell you everything you need to know about what focal length and pinhole size to use plus f/stop size and eposure times-

    http://www.pinhole.cz/en/pinholedesigner/

    Do you have any pre-made pinholes? What size camera are you thinking of building? Please feel free to contact me with any questions you might have.
    Arthur, NYC
     
  3. youwattom

    youwattom Member

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    Nice one Arthur! My focal lenght is 40mm i used a pin for the pinhole to give a diameter of about 0.9mm how on earth can you manage to make and measure the hole any smaller?! If i used a flat bed scanner to measure then it would just scan in actual size? or then do I enlarge. I guess im better of just to buy some. what does the focal lenght effect? NYC... you lucky man!
     
  4. DWThomas

    DWThomas Subscriber

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    There are many ways to get there! The Worldwide Pinhole Photography Day folks have a resource page on line that links to many sources of information. Off the top of my head, 0.9 mm sounds like a rather large hole for a 40mm focal length, but one can over-analyze this stuff too! I have the good fortune of owning a small 50x microscope with a direct measuring scale in an internal reticle. With patience I can measure to about 0.001 inch with that. I believe somewhere in those links is an article that goes into making a pinhole and measuring it with a scanner.

    A common do-it-yourself method for a pinhole is to press a small dimple into a sheet of thin brass shim stock and then sand the dimple with fine wet-or-dry sandpaper, used wet. This results in a pinhole with a desirable knife edge. I have made several that way. They may not quite live up to the commercial laser cut items, but they work.

    It's fun stuff and there's almost no limit to the possibilities.
     
  5. DWThomas

    DWThomas Subscriber

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  6. RalphLambrecht

    RalphLambrecht Subscriber

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    I have this to offer:

    http://www.waybeyondmonochrome.com/WBM2/TOC_files/PinholePhotographyEd2.pdf

    If you have an enlarger (or slide projector), put your pinhole and a piece of paper of known length into the negative holder, rack it up, focus and measure the size of both. The piece of paper will tell you about the magnification,and the measured pinhole diameter divided by it will tell you its size.
     
  7. FM2N

    FM2N Member

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    From what i can remember. Scan the pinhole at at least 1400dpi or larger if possible. Then use the measuring tool that you have in photoshop to get size. If you use the 1400dpi, if my math is right then if 11 dots fit inside the pinhole it is a .25mm hole.
    The focal length= a very specific pinhole size. If not the image will be more soft then you may want. A focal length of 40mm needs a pinhole of about .3mm.
    When making a pinhole first get a clean soda can and cut out a 1 inch square.
    Then find or purchase the smallest needle set you can find. Inset loop end of smallest needle in eraser of pencil(gives you something to hold on to while you rotate the needle).
    You will aslo need some 400-600 grit sand paper.
    The key to making a good small hole is to alow the needle to make a dimple in the bottom of the metal. Then work the dimple with the sand paper until a hole opens up. Working this way should give you a nice small .2-.3mm hole.
    What kind of camera are you making? What type of film?
    I hope this helps
    Arthur
     
  8. youwattom

    youwattom Member

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    You guys are idols, ive manged to make a wooden one to take 35mm but with no photography knowledge just a fasination of the topic its fun but tricky, ive been leaving the shutter open for 35sec+ no wonder i havent been gettin any results!
     
  9. RalphLambrecht

    RalphLambrecht Subscriber

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    I'm glad it worked. Pinhole is a lot of fun!
     
  10. FM2N

    FM2N Member

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    Most likely over exposing the film. Try, in the sun, a 1,2,3,5,7,9,15 second exposure to see what works with the camera and pinhole you have made.
    thanks
    Arthur
     
  11. little golan

    little golan Member

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    well! when I started to want to be a wee bit more precise about my pinhole boxes, and concentrated on the pinhole, it seemed that this, the quality and size of it seems to be the thing. I used a micrometre to measure my sewing needles and was amazed at how most of them were way too big! at least for the tins and boxes I have. But the ones measuring .026, and .028 ( in inches) seem to be the most useful.