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Message: <blockquote data-quote="typo" data-source="post: 3481648" data-attributes="member: 83808">Adhoc,Apologies for jumping in again. I've found a number of published articles relating to this topic which do show quite large (~40%) improvements in tests relating to disease conditions (eg. Low contrast targets) , but the consensus seems to be that for healthy individuals in good light the average binocular (two eye) advantage is around 10%. One interesting point made in the introduction to the attached paper is that the advantage decreases with the complexity of the target. This only relates to acuity of course, the are other quantitative and qualitative differences, of which stereopsis is probably best understood here.Those tests were obviously done without the aid of binoculars or telescopes and I can't find anything published on the topic. In my own tests with binoculars using line charts, 10% improvement was my most common result but there were repeated occasions when I could get up to 25%, but I can't really explain the reason for that variation. I think the magnification illusion I mentioned before isn't relevant to acuity, but I'm sure for most the one eye vs. two eye advantage is pretty obvious. Stereopsis is measurable, and so is contrast but how that perceptually improves object identification, 'as if' the magnification was higher is beyond me and I've not seen anything published on the subject. I've found different binoculars give different results but I don't think George's numbers would be too far adrift as a guide to the perceptual advantage.David</blockquote>

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