Why do different sized cameras result in different angles of view with the same size lens?
Lens length is the distance from the focal node to the film plane. So with a 50mm lens, the focal node of the lens is, you guessed it, 50mm from the film plane. So with our standard Rhino viewport (and a SLR camera) the resulting view angle in plan view would be 39.6 o: Now, if we pop that same 50mm lens onto a motion picture camera, the film plane size changes to 24mm (this format is called Super35): So although you are keeping the same lens length, by changing your film size, you change your field of view.
