On Thu, 26 May 2005 22:52:43 GMT, "Tom Gardner"
wrote:



OBTW, you're using a small aperature as the pin-hole effect produces an
image upside-down.

It's both.

A pinhole can form an image like a lens, but unlike a lens it doesn't
have a focal distance. It'll form an image at any distance, larger
and dimmer for greater distances from the image plane.

A lens, including the one in your eye, forms an image by converging
various rays coming from each part of an object into a corresponding
part of the image plane or retina. The pinhole eliminates all but a
very few rays from each part of the object, so no convergence is
necessary. Therefore, the eye's lens doesn't have to focus, and
aberrations have no effect.