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Hugh - or maybe someone else -- mentioned both umbra and penumbra
cones. One converges and the other diverges. For a finite sized sun
including rays not totally radial or totally parallel - won't BOTH
of these produce a pinhole 'image'.
At 7:42 PM -0400 9/21/03, Bob LaMontagne wrote:
Hugh Haskell wrote:far
Doesn't the size of the spot from a pinhole camera depend on how
that theaway from the aperture you place the receiver? I would guess
beclearest image would occur somewhere near the point where the
"umbral" rays cross. If you take the image size at that point to
thethe diameter of the penumbra, it will necessarily be larger than
theyaperture in the case where the rays are slightly converging, as
1/2are from the sun.
The pinhole spot, as well as the image from any lens used, subtends
degree, same as the sun itself. As you get further from thepinhole, or
use a longer focal length lens, the image gets larger, but still
subtends 1/2 degree.
Bob at PC
--
Chuck Britton Education is what is
left when
britton@ncssm.edu you have forgotten
everything
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(919) 416-2762 Albert Einstein,
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