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Message: <blockquote data-quote="henry link" data-source="post: 1533480" data-attributes="member: 6806">Ron,I'm assuming that the AFOV measurement using the tripod scale method includes distortion because I can see the distortion as I swivel the binocular. I'd never realized before trying this method that the distortion visible when looking through a binocular backwards is the exact reverse of the distortion seen in normal use, so a binocular with pincushion in normal use will show exactly the same amount of barrel distortion when looked through backwards. Of course this makes perfect sense because the distortion is caused by changes in magnification toward the edge of the field so, looking backward, you see the same change in minus magnification reversed. In the group of Nikon binoculars I tested the EII's showed obvious barrel distortion when looked through backwards while the Astroluxe looked just as free of rectilinear distortion from either direction.Henry</blockquote>