I'm building an 8X10 camera, and am presently putting together the ground glass back. In order to get the glass in the correct position, I need to know the corr ect film holder depth. Is there a standard film holder depth for 8X10? If so, wh at is it? Does anyone have any input on which brands of used 8X10 film holders t o buy, and which to avoid? Any advice would be greatly appreciated.