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  1. #31

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    Feb 2008
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    2F/2F - Thanks heaps! That was exactly what I was after!
    If there was a reputation function on this forum, I'd have positive rep'd you for that post! ha ha.
    I didnt know how f'Stops etc were calculated nor had I heard of a nanometer for measuring lightwaves.
    Will be printing your post for future reference!

    Yeah I have Pinhole Designer installed already and have had a bit of a play around with it, but it doesnt help me with understanding the maths behind pinhole design.
    Once I'm comfortable with the formula's, I'll probably get lazy and start using that instead...

  2. #32
    bowzart's Avatar
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    May 2008
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    fast shutter

    Quote Originally Posted by NathanBell View Post
    Almost all of my applications would require a high shutter speed (of say 1/125) so I'm wondering if decent exposure at this high shutter speed is possible?

    I'm just woried that with such a high shutter speed that it wont expose the negative enough.
    I was thinking of using Ilford HP5 400asa 5x7 Sheet film. Pushed if nessessary.

    Is this at all possible?
    Sure, if you are using a lot of flash! A LOT of flash. Or, it would be more likely to be successful if you were simply to move up to the planet Mercury, which is a lot closer to the sun than we are.

    Otherwise, I doubt seriously that you can do it. I won't say you can't (you know, never say never) but actually, I know I couldn't do it. Sounds like endless frustration and disappointment to me.

    Here's another possibility. Use a zone plate. Ready made ones are available from Pinhole resource for $20, or you can make one yourself if you want a custom size. For your 5x7, either the 210mm or the 240 mm would be close to normal. You would gain a couple stops over what you'd have with the pinhole, and the images the zp makes can be really wonderful.

    The shorter your "focal length" (pinholes don't focus, but zone plates do) the more advantage you have in speed. The f/number is related to the square of the distance from the optic to the film, so the longer the distance from the hole/zp to the film, the higher the number (smaller the aperture).

    Why not get a short focal length zp AND move to Mercury? That might just do it!

    I don't believe in smilies, but if I did, they would appear in a couple places here. No derision intended, just my feeble attempt to appear as though I could possibly have a sense of humor!

  3. #33
    bowzart's Avatar
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    fast shutter

    I just got a copy of Eric Renner's book _American Disguise_. In it, he's included a pinhole image of the atomic bomb going off. That was bright enough!

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