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Message: <blockquote data-quote="ronh" data-source="post: 3425229" data-attributes="member: 55514">Henry,Thanks for the excellent work, photographic and observational. I know nothing of the difficulties of photographing a resolution chart in a meaningful way, but if you say these photos are good, then I believe you. This hard data supports your previous observational finding that in daylight, due to the shrunken eye pupil, when only the sweet central path through the optics is used, the 8x56 FL beats all comers. Congrats!Very likely, I would guess, to you the 8x56 beats all comers in all conditions or you wouldn't like it so much.  But to me, my 8x30 Fujinon is the "subjectively sharpest" of a bunch of such good binoculars that I'm inclined to take the effect seriously and wonder about it.  Your measurement (the tape method is impressive in its economy and simplicity) of your own pupils at the binocular being 2.5mm viewing bright conditions, and 4.5mm in the shade, supports my contention.I suppose my eyes are significantly aberrational at wider pupil widths. In this way, I hardly feel like the Lone Ranger, as it is the reason for eye resolution peaking around 3mm rather at larger openings where theoretical resolution should be better.  It is often mentioned in astronomy discussions, which relate to fully open eye pupils, that smaller binocular exit pupils result in the impression of smaller sharper stars, and the above assumption of mine is commonly understood as the reason for the night time effect. I guess the day time effect is smaller, but similar, and noticeable in small doses to experienced observers whose eyes are thus plagued. It is reasonable that you should measure "binoculars", which one hopes achieve a good degree of uniformity, and give the hope of completely objective data, also keeping eyes out of it makes measurement possible for the amateur investigator.  A random lot of eyes undoubtedly vary in quality many times more than a lot of Zeiss FLs!   Even so, there is so much evidence of the exit pupil/sharpness effect at night, and sufficient evidence of it by day as well, that I fear the selection of the sharpest binocular becomes a very personal matter, and binoculars with large exit pupils may not always win the apparent sharpness contest. Not that apparent sharpness is everything.  Eye positioning issues with my 8x30 drive me nuts, and its image is rather colorless as well, problems both addressed by a larger exit pupil.  It is not my favorite binocular by any means, just weird in this one way.Ron</blockquote>

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