Hi, I'm confused about film sizes! I have recently acquired a lovely condition Busch Pressman Model C camera - but I'm totally confused about the size of film it takes - 6x9, 6.5x9, 2x3, 2.25 x 3.25... and so on. Can anybody help? I really want to use this camera, but I want to get the right size for the film holders too! Many thanks, David.