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Message: <blockquote data-quote="OPTIC_NUT" data-source="post: 3172561" data-attributes="member: 121951">Ah, that's sort of an even more holistic view of the confusion I am having.I believe Henry is concentrating on the spherical aberration because he assume it's dominant.                 That assumption seems about right.ElkCub:   you were questioning doing things like star-splitting with binoculars.      The makes sense given the lower powers and the eye's acuity .... seems like it's in the wrong ballpark.      Things like 'seeing' also seem mostly beneath relevance.      If we look at the actual resolution of most binoculars, it almost always finishes up      well inside the apparent angle for most people's acuity, so it's clear the total aberration is OK.      I think many binoculars push that limit by reducing the length as much as possible.      Low power is a defining feature for binoculars, but so is compact length.Henry:  As I read more and more, I realize my fuss over the shape of the MTF doesn't mean much   in general and for portable sporting optics especially.   Thank you so much for your patience.   I do think it can't be too alarming if actual binoculars have sub-human-acuity resolution anyway. An interesting topic creeps in as I look at your graph and the measured graph, though:   the outer fringes of the MTF have consequences on contrast.   I hadn't realized that   before, but it does show up for reflectors, as one example. I worry about that more,   the accumulation of all the fringes of all objects with the MTF.</blockquote>

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