Hello all! I am constructing a 6' x 10' camera obscura out of an enclosed cargo trailer and I need a little help. Essentially it is a big pinhole camera and I need assistance determining the optimum aperture, figuring out focal length, and how to optimize the plane of focus so that it falls on the back wall instead of in front of it or behind it. While I wouldn't mind playing around with some lens element construction, my primary aim is to use it as a pinhole. I may also put a second hole in the side so there are two distances that images project--one that goes ten feet from aperture to back and one that is six feet from aperture to the back. Any and all advice and assistance gratefully appreciated!