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Message: <blockquote data-quote="elkcub" data-source="post: 3452554" data-attributes="member: 14473">Hi Omid,In general, visual perception theory assumes that magnification has that effect (in the ideal case), recognizing that atmospheric effects diminish its influence.  An excellent geometric explanation of this can be found in S. S. Stevens "Handbook of Experimental Psychology" (1962) by C. H. Graham. (p. 888).  Used handbooks can be found on ABEbooks for < $20, which is an amazing bargain.  The Graham chapter alone is well worth the price.A current (more pricey) book entitled <a href="http://www.cambridge.org/us/academic/subjects/physics/optics-optoelectronics-and-photonics/eye-and-visual-optical-instruments" target="_blank">"The Eye and Visual Optical Instruments"</a> by George Smith and David A. Atchison (1997) also goes into expanded explanations of this and many other topics you would be interested in.  One that's rarely if ever discussed is 'pupil shearing' with eye rotation, which goes a long way to justifying the larger exit pupils associated with full-sized binoculars, like 7x42, 8x42 or even 8x56.  Other topics that are discussed include the effect of eyeglass prescriptions on properties of the coupled instrument system, and, of course, the wisdom of employing instrument convergence.  I agree with you, incidentally, that small brightness increases, per se, are hardly important given the adaptation range of the eye.  Much more important is the reduction in light scatter within the system and contrast enhancement.  But I have also felt for some time that improved transmission also makes color fringes more conspicuous, as an unintended consequence, which may have provided the impetus for improvements to control CA with HD glass.  Full ergonomic treatment, I think, should probably take both head and eye rotations into account, lateral and vertical.  Yes?Ed</blockquote>

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