As I see it the camera is looking out of the little hole and the hole is
like the camera is squinting, the tighter the squint the sharper the
image.... Naw, I don't think so.
Actually I don't know what the scientific explanation is but one can
logically see how it works though I am not sure how the infintite depth of
field is explained. If one imagines being in the camera with an eye moving
about on the image plane, one can only see a small portion of the world
outside from any infinitely small point on the image plane. Now imagine
looking out the left side of the pinhole from exactly the same position on
the film plane and one would see a smaller part of the world, and the same
for the right and the up and the down, etc etc. Now the small parts that
can be seen are really almost the same since the hole is so small and so
what happens is that from any part of the image plane one will see an
blending of the image from the right, left, up, down, etc of the pinhole.
Since the image is almost the same, but not quite there will be some
bluring. One could imagine a round 4 foot window as being a pinhole, but
since the images (infitnite in number really} from the up, down, right and
left are so different from each other, the integration is so radical, that
the blending is for all purposes complete and so you really get a white
patch of light. I suspect in theory a window actually casts some extremely
blurry and faint image that is probably impossible to measure.
The further you are away from the pinhole the less on could see of the
outside world through the pinole so this would explain why a largeish hole
in a darkened room would cast a recognizable image on the wall.
I guess the infinite depth of filed can be explained by just applying this
to any point inside the camera and forgetting about the image plane in a
film plane paradigm.
The best I can do for now.
Dick Sullivan
Bostick & Sullivan
PO Box 16639, Santa Fe
NM 87506
505-474-0890 FAX 505-474-2857
http://www.bostick-sullivan.com