From: Joe Smigiel (jsmigiel@kvcc.edu)
Date: 12/17/02-11:36:21 PM Z
Darryl,
This is the only time I've ever used anything from that trigonometry course I attended at U of M-Flint. You can determine the exact distance the pinhole would have to be located from the film based on the angle of entry of the light rays through the pinhole. The thickness of the material will limit the angle of view, i.e., the angle which light passes through the hole.
Picture that 1/4" thick sheet with a pinhole diameter of 1/32". The sheet reduces the angle of entry 'cause light hits the wall of the sheet. Now if you reduce the thickness of the sheet to say 1/64", some trig or a simple sketch will show you that the angle of view will increase. Just figure out the vignetting based on shim thickness and that will tell you where to put the film to get a circle rather than full coverage on the negative.
sine-ing off,
Joe
<<< dbaird@umflint.edu 12/17 10:44p >>>
Joe wrote:
>In terms of pinhole cameras, I believe the limiting factor on whether the camera is actually a "wide angle," etc., has to do with the thickness of the pinhole shim. You could drill a small hole in a 1/4" thick piece of aluminum to use on a camera, but that pinhole would have a very narrow angle of view compared to the identical diameter hole drilled into a piece of aluminum foil, regardless of the focal distance of the camera.
>
Wow this is very interesting, can you and anyone else pick up on this
idea. I'm working on a new design for a polaroid pinhole camera that I
want to control the circle of confusion to be very "round" on the
negative. (PPN 665).
thanks
btw, what a great thread folks...
Darryl
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