----- Original Message ----- From: "Paul Prober" <pro...@silcom.com>
The problem experimenting with different pinhole sizes is that unless we are making exposures of resolution targets http://www.???????/resources/articles/Young/images/fig5.jpg the results will be always subjective to each viewer, scene, image contrast, whether subject is at close or far from the camera, angle of view, etc, and/or a combination of the above. > I have not experimented to find the optimum pinhole size. Chris Patton > has, and his conclusion was that the Prober-Wellman Formula is a practical > values to use for f/stop to pinhole size for reasonable Circles of > Confusion. > See http://www.stanford.edu/~cpatton/phcalc3.htm which uses the > Prober-Wellman Formula. Patton actually uses a different formula or maybe I should say different "constant" as all formulas since Lord Rayleigh (1890's) are basically the same. Patton actually has found that bigger pinholes than what most of the rest of us consider "optimum", gives him sharper images. OTOH, you have Larry Bullis going the oposite way, that is, he finds that smaller pinholes give him sharper results. Myself, my eyes, rather, are more inclined to align with Larry than with Patton. > or > http://www.huecandela.com/hue-x/pin-pdf/Prober-%20Wellman.pdf for the > white paper study. > Also the formula can correct for pinhole to subject distances, for Close-up > and Micro pinhole pictures. The Prober-Wellman Formula is exactly what science has been telling us the optimal pinhole formula should be D= SQRT (2.44 * Lambda * F) , the SQRT(1 / M+1 ) factor is a sort of "bellows factor" as I explained it in a post back in Oct last year: http://www.pairlist.net/mailman/private/pinhole-discussion/2001-October/0042 23.html Guillermo
