Date: Sat Apr 14 18:01:15 2007

Author: Urs Lauterburg

Subject: Re: [Phys-l] pinhole camera

Post:
>I presume that everyone knows that a "pinhole image" is NOT an image.

Dick,

Well a painting is an image too and so are maybe
even my thoughts and visions psychologically, but
admittedly not physically ;-).

However a pinhole camera image is indeed a very
complex phenomena of light. There is the easy
explanation where rays from all points of the
objects pass straight through this tiny hole to
the back of the black box to form an inverse
replica of the illuminated world outside of the
box. It's an almost philosophical arrangement and
no wonder many photographers have liked to play
with pinhole cameras ever since there was
photography.

When taking a closer look at how the camera
works, things quickly get complex. The question
about the best size hole takes you to diffraction
effects, the Schwarzschild effect and then does
the hole have to be round? A good example for a
simple thing like a black box with a hole being a
temptation of the ignorant to ignore the true
complexity involved.

It always strikes me how geometric optics is
commonly perceived as something very precise, yet
everything is just based on approximations....
well approximations which enabled the optics
industry to develop some very fine equipment for
imagery.

Well so much my 0.0001 worth of a comment on tap-l about pinhole camera

Urs

Urs Lauterburg
Physics demonstrator
Physikalisches Institut
University of Bern
Switzerland



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