Ysset writes: > Karl, > > Then does it follow from here that > 1-The ONLY reason we loose resolution when we blow up an image on the > film is because of the grain and other impurities of the film itself, yes.. > and > 2-The resolution power of the optical system (lens) is infinite. the quality will fall away progressively the greater the enlargment, so no. There is no perfect lens, there will aways be some physical constraint which limits resolution. Lets look at an 8x10 image made with a low res 8x10 camera on 100ASA film. The image will look good and the grain will not be the limiting factor to the sharpness or quality of the image. Typically, large format lenses are _not_ high quality compared to smaller formats because traditionally there has been no need for them to be fantastic - the images are usually enlarged less than with smaller formats. An image made with a 35mm enlarged to 8x10 (also 100 ASA) will show the grain as it magnified more. modern 35mm lenses are far superior in optical quality to medium format, and medium format are superior to large format lenses (so sticking that lovely 47mm Schneider Super Angulon on a 35mm camera is pointless, the quality simply ain't there!) but there is a limit. Take a picture with a 35mm fitted with a 50mm (normal lens) of a fly from across the room and enlarge it and it's head will be an indistinct blob, barely discernable from every other blob that forms the image as the film resolution cannot cope with that degree of enlargement. If we had a really huge format like say 24x36 inch and a half decent 'normal' lens (1100mm) then we'd get a better image and we _would_ be able to see the flie's head. it would be no different from using a 1100mm lens on a 35mm camera - only the format of the film has changed. karl
