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Message: <blockquote data-quote="henry link" data-source="post: 3252616" data-attributes="member: 6806">David,Very interesting. This image of the circles indicates a compound distortion of exactly the opposite kind from the Swaro. The three left circles show very slight positive AMD. I measure the ratio of vertical to horizontal of those circles as 1.03, 1.04, and 1.02. Then the last circle switches to negative AMD with a ratio of .94. Just as you say this indicates slightly less pincushion than required to fully correct AMD until an abrupt increase in pincushion at the periphery results in overcorrection of AMD near the edge.I hate to ask you to do more, but just as a check of the phone camera's distortion you might try making a couple of photos of a circle centered in both the binocular and the camera fields where there should be no distortion of the shape. Make one photo with the camera axis parallel to the binocular and the other with the camera tilted the same way it's tilted for these photos. That should tell us whether tilting the camera affects distortion.Henry</blockquote>