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Message: <blockquote data-quote="Omid" data-source="post: 3622086" data-attributes="member: 16724">Hi Ed,Yes, there will be some dispersion and a small amount of astigmatism to deal with. But these have well-known solutions: For dispersion, the prisms can be made <a href="http://taylortechassoc.com/?page_id=1344" target="_blank">achromatic</a>.  Or one can use low-dispersion glass. Also, both dispersion and astigmatism can be corrected by having prisms in front of the objectives and after the eye pieces such that a) they produce deviations in opposite direction and b) the power of the prisms after the eyepieces are N-times larger than those in front of the objective. N here is the magnification of binoculars.Other techniques can  be used to correct for errors as well.</blockquote>