on 4/6/07 6:40 PM US/Central, George Brock-Nannestad at [log in to unmask]

> There are several factors involved in good stereoscopy. First of all, each
> image must obey the rules of perspective, which means that the angle
> subtended by an object must be close to the natural angle of observation. For
> an ordinary telephoto image that means that you must see it from such a long
> distance that you really do not draw it closer, and a wide-angle image must
> be seen with an eye so close to the image plane that you may not be able to
> focus and hence you need to use a lens - usually called a magnifier. All of
> this makes for some simple geometrical calculations.

While I'm sure this is especially true for stereo images, isn't this also
true for other images?

I recall calculating many years ago that the most accurate perspective for
enlargements made from 35mm negatives and slides, when held by hand at a
normal viewing distance, was achieved with lens focal lengths of 35mm for
enlargements made at 8"x10" and 28mm for enlargements made at 11"x14",
respectively. I rounded these figures to readily available lens focal
lengths and print sizes.

Parker Dinkins
MasterDigital Corporation
Audio Restoration + CD Mastering