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Message: <blockquote data-quote="elkcub" data-source="post: 3305526" data-attributes="member: 14473">Right on.  :t:  My preferred instrument is the SLC-HD (original), not the SV.  However, leaving my personal grail aside, the reasoning goes as follows:I've added some notations in red to Fig. 1 from Daniel Vukobratovich's classic paper, Binocular performance and design, published by the SPIE in 1989.  As can be seen, theoretical (or ideal) efficiency increases 1:1 with magnification.  However, all real binoculars are compromised by various factors, a very important one being hand tremble.  Without being supported, the asymptotic efficiency level of handheld binoculars is approx. 7.0.  In other words, no matter how large the magnification the efficiency never exceeds about 7.0 — unless the binocular is supported, i.e., by a tripod.  Otherwise stated, handheld binoculars don't perform better than ideal x7 binoculars.With maximum support, which eliminates tremble, efficiency is still not theoretically perfect, but a significant improvement is realized.  For example, a 10x binocular improves from about 5.5 to 8.8, an increase of (8.8-5.5)/5.5= .6 or 60%.  My guess is that the support provided by an IS mechanism, like the Canon's, might not be quite as effective, perhaps only improving the binocular by 40-50%, let's say for an efficiency of 7.5.It should be evident from the graph, therefore, that a 15x or 20x handheld binocular may be expected to perform arguably worse than a stabilized 10x, and in that respect it replaces them with one instrument.Kimmo seems to be on to something important!  :smoke:Ed</blockquote>

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