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Message: <blockquote data-quote="Alexis Powell" data-source="post: 1355942" data-attributes="member: 5327">Hmm....your comments help clarify for me that I appreciate the sharing of opinions about things that are matters of opinion, but that for technical topics I much prefer thoughts and speculations that have been tempered/honed by familiarity with the hard-won accumulated knowledge of others (the understanding the community, one's predecessors, the "scientific" record).  I don't see that there need be any conflict between use of mathematics/optical equations and "facts" acquired through observation/empiricism, and I like for discussions to include both approaches used together.  For sure, for sure, but discussions of apparent depth of field will be much more useful if commentators are aware of all these factors, have some sense of the role that they play, and discuss the effects of these factors rather than their subjective composite impression of the amount of DOF a bino has.  Example 1: It is common for reviewers to conclude that binos with fast focusing ratios have a narrow DOF.  By recognizing the basis for the illusion, one can learn to turn the focus knob more slowly and avoid overshooting the point of best focus--magically, the bino now has normal DOF!  What it looks like can thus be strongly affected by knowledge of what it is.Example 2: Reviewers 1 and 2 evaluate the DOF in a binocular with strong field curvature, but neither is aware of its influence.  Reviewer 1 looks at a prairie landscape and notices that when centered on the distant horizon that the scene seems quite sharp from very close in the foreground all the way to the horizon and sums up the experience with the conclusion that the bino has tremendous DOF (in comparison to another model, with a flatter field, tested against it).  Reviewer 2 looks at a bird and notices that when focused on its head in the upper part of the FOV, that its tail, which extends into the distance, is very blurry as seen in the lower part of the FOV, and concludes that the bino has very shallow DOF (in comparison to another model, with a flatter field, tested against it). Because of these sorts of confusions, unless the circumstances of testing are described in detail, comments on DOF tend to be meaningless and of no practical use.--AP</blockquote>

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