From The Keppler Files: November, 1966

There is no absolutely foolproof way of evaluating optical ability except by actually taking pictures and looking at them. There are too many variables: sharpness, contrast, coloration, flare are only a few of the optical ingredients and each one of these must be broken down into the sub-ingredients. Couple this to the whole mess of variations in films, processing and viewing, and you can see just what chaos optical science is up against.