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Message: <blockquote data-quote="ronh" data-source="post: 1534065" data-attributes="member: 55514">Are we on the same wavelength? Ed,I don't want to try too hard to pass the web forum limit of exactness, but to tell the truth I don't understand what you mean about color fringing. Perhaps, that minimizing fringing is a visual focus criterion? Or perhaps that fringing softens the image enough that truly sharp focus becomes impossible, thus the eye/brain plays a new game and becomes more tolerant of defocusing in an image that is essentially flawed in the first place? I'm sorry if I have it all wrong. Still it is sort of stimulating the way you and Jean-Charles are running advanced concepts by!But I'll try to clarify what I meant. First, I believe that a bright-light-responsive closed down eye perceives a greater DOF. This is partly due to the increased effective focal ratio in the bino from the exit pupil stopdown, similar to the effect in photography. It is partly due to a similar effect in the eye, which also acts like a camera. But, I think that there is a concurrent effect with bright light, which works on DOF in the opposite direction. Brighter light allows one to see better, enabling more critical focus, and making one less tolerant of poor focus. This tends to diminish the apparent (hey, the only kind!) DOF in bright light. I really shouldn't belabor this idea, since the first effect is dominant. Just spoutin' off!Ron</blockquote>