Steve Hodges <shodges@wantree.com.au> writes: > Christiane Roh wrote: > > > > If one were doing the math (anyone ?) > > Yes? Surely the simples way to understand what's going on is as follows: As you change the aperture, various details of the image change (depth of field, marginal aberration effects, etc.) but the overall form of the image does not change at all. If you stop the lens down far enough, it is indistinguishable from a pinhole. But a pinhole simply works by straight-line projections, and if you move the film plane closer or further from the pinhole the image simply scales up or down in size, without any overall change. (<ot>This is the universal projection onto a flat plane: there is only one way of doing it, so despite claims that people "invented" "central projection", actually they were just *discovering* successive approximations to correct projection.</ot>) But as you move the pinhole in and out, this corresponds to different lens focal lengths. Therefore the focal length of the length cannot grossly change the form of the image. (Er, was that mathematical enough?) Brian Chandler ---------------- geo://Sano.Japan.Planet_3 http://imaginatorium.org/
