> Not really. The fact that the 50 has a field of view more like a 75 is > created by cropping, not optical zooming. In effect, the > less-than-24x36 image sensor size means that there's a permanently > enabled digital zoom feature on the camera. > > All you're doing is cropping. The perspective-flattening effects of > longer optics aren't going to come into play (or will they? maybe I'm > the confused one).
Well, perhaps. The fact is, you could say the same thing about any smaller format. You could say that "all you're doing" with rollfilm is cropping the field of view of 4x5 film, and "all you're doing" with 35mm film is cropping the field of view of the rollfilm. A 300mm is normal on an 8x10 camera, moderately telephoto on a 4x5, long portrait length on a 6x7, and long telephoto on 35mm. As far as PERSPECTIVE is concerned, it doesn't change with focal length anyway. If you took a picture on 8x10 film with a 300mm lens, then cut out a tiny 36mm x 24mm piece from the middle of it, that little piece would have exactly the same perspective as would a piece of 35mm film aimed at the same target with a 300mm 35mm lens. No, the pictures wouldn't look exactly the same, because the smaller camera would resolve better. But in terms of "flattening" they'd be the same. So, yes, the 50mm lens on an APS sized sensor would have the same angle of view, d.o.f. at same aperture, perspective, and "flattening" effect as a piece of 35mm film cropped. But so would a 75mm lens on a full-sized piece of 35mm film. Hope this is clear. This is one of those perennial questions in photography--it just always comes up again and again and again. --Mike
