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Message: <blockquote data-quote="brocknroller" data-source="post: 3240541" data-attributes="member: 665">To expand on this point... besides the advantages of larger exit pupils, which allow you to see more detail in low light (provided your entrance pupils open wide enough to match the bin's exit pupils) and the fact that the larger exit pupils keep veiling glare out of the way, the advantages of the longer focal length of a 50mm bin vs. a 42mm vs. a 32mm can be seen when the the 50mm is "stopped down" by your pupils contracting from exposure to sunlight. The daytime view through a 10x56 SLC might be even better due to its longer focal length. Henry Link explains how the longer focal length 8x56 FL makes the daytime view exceptionally clear: <a href="http://www.birdforum.net/showthread.php?t=81438" target="_blank">World's Best 8X42: The Zeiss 8X56FL</a>He sums it up: The point of all this is to show that the 8x56 really has no better (perhaps slightly worse) optics than the 8x42 when they are compared at full aperture, but when the 8x56 is stopped down to 42mm and below it shows significantly lower aberrations than the 8x42 (at the same aperture) simply because the 8x56 focal length is longer. If the 8x42 had the same focal length it would certainly perform just as well.</blockquote>