Originally Posted by nzeeman
i know it very well-perspective of for example 25 lens is distorted and that is why people used short tele for portraits because it keeps facial features closest to real ones.. if they could use 50mm and just crop it - they would surely do it without need to buy 70mm.. but face looks narrower on 50mm not to mention 35 and wider focal lenghts.. focal length is not same as field of view-you seem to mix those two.. even if you put 50mm lens on point and shoot camera you will keep all 50mm characteristics just will have cropped small portion of it...
You're wrong. For instance a 35 on APS-C and a 50 on FF give the same image, if we leave depth of field out of it. Exactly because
"focal length is not same as field of view". Please do try it empirically. Easy to do if you have two lenses of different FLs or a zoom, and can make a crop. Or try this simulator: https://imaging.nikon.com/lineup/lens/simulator/