hi everyone, i went to the fuji website and had a look at fuji FP100B B&W . the film image size is 3 1/2 ish X 4 1/2 ish. do they make a 4x5 'full size' instant film or is this the closest? i'm a bit confused because i'm using this polaroid back - one that slides in like a fat darkslide (hence i thought 4x5) , and the image size it yields is approx 3 1/2 x 4 1/2. thanking you all in advance!