I'm making a 4x5 pinhole camera and I want to go as wide as possible. I'm looking for suggestions on what's the shortest focal length that will cover to the corners and also what size to make the pinhole to optimize sharpness out to the corners. At this point I think making the pinhole slightly bigger than the Rayleigh formula recommends might be a good start, but I'm unsure just how short of a focal length is practical. I think if I use Tmax and expose properly I will be able to burn in the center enough to conquer tonality from falloff, but I am more worried about sharpness.