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Message: <blockquote data-quote="Omid" data-source="post: 3631936" data-attributes="member: 16724">Hi Ed,Thank you for the tip! There is another book (which I think you introduced to me in 2015) titled "Binocular Vision, Foundations and Applications" by R. W. Reading. It has the same drawing shown on page 288. Reading's book and the one you mentioned both cite a 1952 paper by K. N. Ogle called "Distortion of the image by ophthalmic prisms". Do you have access to this original paper by any chance? I understand that the distortions caused by the prisms (color separation, astigmatism and some field curvature) need to be considered and mitigated. But this is no more difficult than doing same with distortions caused by lenses or other optical elements used in binoculars. The color separation can be easily solved by using an achromatic prism. Astigmatism and field curvature can be reduced by slightly tilting the prism or by using a prism in reverse orientation at the ocular side of the binoculars! As you and Bill mentioned, we can also rely upon human eye/brain adaptation. Another note: When I suggest positioning prisms in front of the objective, the "bending" required is in the order of just 1 degree. This is far less than the bending used in ophthalmic applications. So, the distortions caused are far less..Thanks again,-Omid</blockquote>