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Message: <blockquote data-quote="ronh" data-source="post: 1649203" data-attributes="member: 55514">Ron,I am impressed at your IPD investigation. Since you obviously might care, I'd like to share my way of setting IPD for infinity viewing. You need a well lit fair sized room with a good mirror (I don't think anything better than a normal dressing mirror is required). Viewing through the binocular, look at and focus upon your own reflection. You will see your pupils, nearly filling/just filling/not quite filling the objective lenses, depending on the illumination. You need to adjust the illumination so your pupils appear slightly smaller than the objectives, so it will be easy to center them in the objectives. A mount or solid brace is needed for the actual adjustment. Closing your left eye, move your right eye so that its pupil appears centered in the objective. Now, without moving your head, close the right eye and look with the left, and adjust the IPD until both pupils, viewed in turn, appear centered in their objectives. I claim that in order for this condition to be successfully reached, 1)the binocular line of sight must be perpendicular to the mirror and 2) both eyes must be centered behind the eyepieces, a claim against which I would appreciate criticism.Also look out for the creepy effect of the enormously enlarged eye pupils, real monster movie stuff. This brings home the power of optical aid in a unique way!Ron</blockquote>