After working on a camera one needs to make a test, especially if a lens has been exchanged or the camera is not a view camera. I have a large black piece of foam core with a US Air Force test target, a large sheet test target with 3 bars running in every direction and size, a Color Checker, a Kodak step gray scale and an 18% grey card on it. The question is this: Is there an optimal distance from the lens to test performance for comparitive reasons? I think I have read that 100 times the focal length of the lens is standard. Close and filling the frame certainly reveals barrel and pincushion but doesn't tell much about real life situations. What I really want to decide is, after all my modification is "this" better than "that" and unless the "test" compares only one different thing, ie: the lens etc. then I'm back to subjective comparisons. Discuss, shoot holes, badmouth, call me a fool, advise, etc.