On Apr 19, 23:36, Tony Duell wrote: use that Hi-res 35mm is probably better than that. Kodachrome certainly is; it can resolve a couple of thousand lines per *millimeter* under ideal conditions. Even fairly conventional fine-grain black-and-white films have been able to manage 1000 lines per mm since the 1940s. That means if you take the full height of a 35mm image, and enough of the width to match the typical aspect ratio of a digital camera (lets say 3:4), the image could resolve the equivalent of 24000 x 32000 = 768M pixels! It's not quite as simple or dramatic as that, of course. It's not just the resolving power of the film that affects the image quality, there are irradiation and halation effects to consider, as well as graininess, lens quality ("the diameter of the circle of confusion" is a phrase I will never forget). On the other hand, there are digital artefacts like edge effects to think about too. Even if you take a normal fine-grain silver halide image, under average conditions, you'd have about 15M pixels (I found that in a few references on the web). That's about 5 times more than a 3.1M pixel digital image -- except they're analogue pixels, in a sense; the size and colour are infinitely variable, not variable in discrete steps. Moreover, 3.1M pixels in the camera aren't 3.1M pixels in the final image. It depends how they're used, but in the camera, you typically need three pixels, one for each of R, G, and B, to get one RGB pixel in the image. Some techniques use even more (the Bayer algorithm uses 4). -- Pete Peter Turnbull Network Manager University of York