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Message: <blockquote data-quote="Surveyor" data-source="post: 1531565" data-attributes="member: 50720">Kevin, To get a better idea of what John is describing put a bino on a tripod and look through them backwards. Since the image will be the inverse of the power, i.e. 0.125x instead of 8x, you need to find a very high contrast target, such as a dark building edge against the sky, and align one edge of the field stop with that edge, then rotate the binocular, while paying attention to the amount of rotation, until the other edge of the field stop aligns with the high contrast edge. You should have rotated the bino about 50 or 60 degrees. If you use a large protractor or have a tripod head marked in degrees you can get a pretty good idea of the AFOV. I use this method, but with the bino attached to a survey instrument, to get better readings at longer distances than John describes to minimize the distance errors, typically a kilometer or more. Hope this description is clear, if not I can attach pictures later. Best.Ron</blockquote>