I think its a bad idea to think of it as a magnification factor, as its really cropping the edges. One thing that annoys me is that even though a 50mm becomes the right length for a portrait lens, its not as flattering as really having an 85mm focal length on the camera. Also my standard lens is a 24mm lens and using this lens as a 38mm (i'm using a 10d) the images are no where near as compressed as they would be with a 35mm or 40mm lens on 35mm file.
Regards, Paul
