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Message: <blockquote data-quote="elkcub" data-source="post: 1356252" data-attributes="member: 14473">Ronh,Adding to Henry's comment, however, I do think you've put your finger on an important point, namely, that the observer's perceptions don't always have (perhaps most often) directly measurable physical counterparts.  I mean, in particular, those perceptions that we have a phrase for, but for which we struggle to find a unique physical index.  Try to find an index of beauty, for example — even a complicated one.    So, in this case we have physical optics, and we also have visual perceptions, which, at the end of the day, underly our overall appreciation of the "view."  In this instance, visual depth of field is a mental construct that results from a large number of sensory cues and personal variables.   Optical depth of field has a specific theoretical meaning (or a limited number, anyway:^) ), but doesn't conveniently correspond with the overall perception.  In fact, it my be only a small part of the perception.  We always need to know, therefore, which domain is being discussed, and should probably say "visual" DOF or "optical" DOF, if the context doesn't make it clear.  I must admit to being somewhat complicit in this conflation of terms, particularly with regard to advertisements suggesting that advances have been made in optical DOF.  For those who are confused, however, there is no question but that the same optical parameters that affect DOF in a camera also apply to binoculars, i.e., f, f/#, and A.  The only difference is that other than contributing a scaling factor based on magnification, the parameters all belong to the observer's eye not the components of the binocular.  (Conditioned on the exit pupil being smaller than the eye's pupil.)EdPS.  Thanks for the Gordon & Lord paper.  At first blush I suspect they are using a different definition of DOF.  Keep in mind that astro observations are all made at optical infinity, and the eye is a completely different instrument when dark adapted.</blockquote>

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