Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: Camera obscura

On Saturday, Aug 16, 2003, Bob Sciamanda wrote:

. . . some of the low priced web cameras on
the market today use a pinhole in lieu of a lens.

That is new to me. It can be a good topic to
discuss in a class. Knowing how small pixels
are, and other geometric parameters, one
would suspect this to be impossible. The
pinhole providing a single-pixel geometrical
resolution is likely to be so small that the
diffraction would prevent the expected
resolution. I am probably wrong; in the past
I did take good pinhole camera pictures on a
film. But that film was 35 cm from the pinhole.
The web cameras are probably several times
shorter.

The issue is worth addressing numerically, for
example, as a problem in a textbook, or in class.
Keep in mind that a pinhole too small for light
is not necessarily too small for X-rays.
Ludwik Kowalski