You might look for an old Kodak 3A. They used postcard size film, something like 3.5"x5.5". I got one in terrible condition in a box of cameras. Took the lens/shutter off and mounted in a board for my 4x5. The lens is a 173mm f7.7 I think. Covers 4x5 with room to spare. Different models of the 3A had different lens/shutter combos. Some had very nice dial set shutters, some just had the simple ball bearing shutter like the one I have.