I just completed a 6x9 camera and was interested in building one that was either 6x12 or 17. When I built the first camera it originaly had a frame size of 6x11, first negatives indicated that due to viginetting the image circle was closer to 6x8. I have been using the Mr. Pinhole download for determining focal length , pinhole size etc. In doing so I have not been able to determine a pinhole/focal length that would provide negative coverage for a 6x17 unless my focal length was 90mm plus. I have seen a number of cameras on various sites that seem to do this without having the 90-100mm focal length. The camera I built was 29mm and uses a pinhole of 0.010. Any suggestions?