I'm a student at NAU, and I have a two teachers with conflicting views on crop sensors and their effect on focal lengths. One teacher insists that because the sensor is smaller, it works much like going from 35mm to 4x5. So an 85mm lens is a telephoto on a 35mm frame, though it's quite short on a 4x5 camera. The other teacher insists that an 85mm lens is an 85mm lens, regardless. So the perspective from an 85mm lens is the same, no matter what. This concerns me because I've been using a 50mm lens (80mm on a crop sensor body) as a portrait lens. Now I'm concerned that I'm not getting the perspective I want for my portraits. So which is it, anybody?