> > But in ordinary 35mm photographic applications 50-60 lines per millimetre on > the film is great ... and good enough for nice big prints; which will not > show more than about a tenth of this anyway.
A slight exaggeration. An 8x12 print from a 35mm original is about 8x enlargement. So if the image on the film is 60 lines/line pairs per mm, and we don't lose too much in the printing process, we could get theoretically something approaching 7.5 lines/mm, or almost 200 lines/inch. We *do* lose something in the printing, of course. But I've got 8x10 prints where it is quite easy to see detail at better than 3 lines/mm - closer to 50% than 10%, even assuming I managed to get 60 lines/mm onto the film.
