What is the formula for caluclating the depth of field for a given lens focused at a given distance at a given aperture? I don't mean the hyperfocal distance. I need to be able to figure d-o-f for macro work as well as for work at more no rmal subject distances. I now I've seen this somewhere, maybe in of of Adams' b ooks, but I haven't been able to find it. I also recall encountering a web page feature somewhere that would calcucate d-o-f hwne you plugged in lens, aperture and distance data but I can't find that either. Thanks.