> The way it makes the most sense to me is to think in terms of the film > moving. You've got a cone coming out of the back. The further back the film > plane the wider the lens. > > > > > x > x x > x x > x x > x x > x x > x x > > > Your piece of film needs to fiit inside that cone. So if you only change the > film size the same lens can go from very long to wide.
Nick, That's a good way to put it. --Mike
