----- Original Message ----- From: "Zami Schwartzman" <zami...@netvision.net.il>
> the buurs on the oposit side had to be very carefuly treated with no. 400 > sandpaper to get a perfect hole . Although not a sraight forward job , I can > get perfect holes as small as 0.05 mm diameter FYI, such small pinhole would be "optimum" for a camera with a 1.85mm focal length!! A bit impractical, if you ask me!! > I experimented with a 0.1 mm hole , got some good close up pictures well > exposed with Kodak gold 400 ASA( using f: 120 on the light meter ) but the > results are quite " out of focus " on 10x15 prints . -Your f/stop should be f/280 and not f/120. -f/stop is given by dividing the focal length by the pinhole diameter (28/0.1 = 280) -As pointed out by erick...@hickorytech.net, you should be using a pinhole 0.00784" which is equivalent to 0.2mm. The 0.1mm pinhole is producing too much diffraction. -If you want relatively "sharp" 10x15 size results, I would suggest you shoot medium format or larger. > I wander if going further to a 0.05 hole will worth the panelty in the f > number . Only if you could mount that pinhole about 2mm from the film plane. The resulting image, BTW, would be a circular image no bigger than some 10mm in diameter. > Is there an optimun hole size for best sharpness ? or is it the smaller > the better. Take a look to this http://members.rogers.com/penate/pinsize.htm Guillermo
