Drew, while I am all for hands-on experience (Try it!, as Fred Picker would exclaim), and I practice with such matters as often as able (I just read about a focusing technique on this forum and was out practicing in hours); and while I would be extremely unlikely to use a 135 at 3' to make a portrait in attempting to get more DOF than my 210 would allow at 5', I was inquiring here about operant principle explaining the difference between what has been stated by some accomplished authors and what the calculator showed. Really, that's all.
If we understand a principle, we can apply it, e.g., the three variables determining DOF. My question here was a derivative, which it seems to me I managed to explain reasonably clearly in my OP.
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