From: "Rune Tallaksen" <tall...@alfanett.no>
Mount the pinhole sheet in a slideframe, place it in a slideprojector.
Then by measuring the distance from the pinhole in the slideframe and to
the
projector screen and the diameter of the projected pinhole on the screen,
by
means of a formula it was possible to find the exact pinhole size. Anybody
out there that know which formula (s) to use??
Do this:
Mount your pinhole in a slideframe and project it, focus your projector and
measure the pinhole projected diameter.
Without altering your projector set up, find the Magnification your
projector is set for: mount an empty slideframe in the projector (do not
touch the focus) and measure its projected size.
Remove the empty slideframe and measure its size. The magnification will be
given by:
Magnification = Projected slideframe size / Actual slideframe size
Your pinhole diameter will be given by:
Pinhole diameter = Pinhole projected diameter / Magnification
NOTE: use the same units of measure in all the steps.
Guillermo
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