me@myplace.to writes: [snip] > A reply to my post appeared, differing with mine, and I answered with a > suggestion of a simple exercise and almost simultaneously felt the pain of > a kidney stone as it moved into a new and interesting location in my right > kidney. ... Aha! See http://www3.yomogi.or.jp/chandler/pics/14stn1.jpg > To get right to it, I'm sure most people know the gist of the replies to my > statement above. With two exceptions I've seen it all before. The main > thrust is that the only way to change apparent spacial relationships is to > change the observers position. The argument got a bit long, and I got a bit lost, but do you accept this bit? That is, do you think that jiggling the zoom lens can allow you to see around corners? > This ignores the fact the formula for finding the > focal length for a given pinhole is diameter of pinhole times itself times > 750 so the FL of a .4mm pinhole is 120mm. It is? How would you calculate that? How would you account for the fact that with a pinhole of "focal length" 3 ells, a film 7.4 attoparsecs >from the film, and a subject ranging from 3 mm to 4 miles distant everything is equally "in focus" modulo diffraction effects? Can you draw some sort of diagram explaining the paths traced by light rays in arriving at a point of focus of a pinhole? > This shows just how sharp a pinhole shot can be if it is exposed at the > proper focal length for the size of the pinhole. When you move a pinhole > back and forth you are NOT changing the focal length, you are just moving > it in and out of focus. This does seem to be counter both to theory and practice... ??? > Every lens has a "normal" format and every format has a "normal" lens. It does? And how do you calculate this "normal" lens/format? Can it be empirically determined? Or just looked up in an old book? Sorry, too many questions? Brian Chandler ---------------- geo://Sano.Japan.Planet_3 http://imaginatorium.org/
