When purchased, I was told that one shortcoming of my Sinar X was that it was limited to the 4X5 size. (I have never really thought of this as a shortcoming since I bought it for 4X5 work and had a studio full of other cameras - including multiple 8X10). A while back, I was told by someone who claimed that he knew -- that It WAS possible to do format changes (ie: 5x7 or 8x10) but it took a little doing and Sinar wasn't about to tell you how! Oddly - time did not permit , and the guy in question did not tell me how either. Now, I am retired - with time on my hands (Don't tell my wife -- she will have projects for me!) and these puzzles keep my mind spinning -- anybody know for sure about format changing a Sinar X??