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Message: <blockquote data-quote="henry link" data-source="post: 3193881" data-attributes="member: 6806"><p>I think I detect some confusion about the effect of diverging fields. The divergence illustrated in post #1 of this thread does not require the eyes to toe outward in order to merge objects. An object at an infinite distance like a star in the left field is shifted off-center toward the right side of the field and and the same object is shifted off-center toward the left in the right field. Merging the two images into one object requires the eyes to toe inward just as they do when examining close objects in any binocular. So, we already deal with this kind of displacement all the time when using binoculars for birding. For instance, we see about a 20% divergence of the fields every time we look at an object at a distance of about 5m through an 8x Porroprism binocular with a 60º AFOV. IMO, the most troublesome optical effect of this kind of displacement is that an object cannot be well centered in both sides simultaneously. In the case above a "centered" object is viewed about 6º off-axis in both sides. If this same amount of displacement is built into the binocular design then the displacement of a centered object at 5m would be doubled to 12º off-axis in both sides.</p></blockquote><p></p>