Bill, you claim:
I disagree with two points (which means, just so you don't get confused - both of them!): 1) "Every musician" has not learned that a capo causes detuning - the pros and semi pros (and heck, most of the students) I work with are smart enough to know how to use one so that it DOES NOT cause tuning problems - simply place it, as you would a fingertip, as close to the fret as possible and use only enough pressure to fret the notes. Your example of bending behind the nut is an invalid comparison - behind the fret you have perhaps a few 64ths of an inch from fret crown to fretboard, while behind the nut you have 1/8" -1/2" or more. You CAN'T duplicate the behind the nut bend unless you go *sideways*. I realize you mention that it IS a larger "bend" - but bringing it up at all invalidates your premise. 2) In that your entire basis for comparison/testing is invalid (apples vs oranges) there can be no "common sense deduction" (and I know of no one BUT you that thinks this "issue" is common sense).He's having a problem accepting what every musician has learned, and for some unknown reason refuses to accept a common sense deduction.
To add to the poor example you gave - not only are the "bending" distances different, with a capo you don't press the strings down to the fretboard anyway - your press them only *to the fret* - unless you don't know how to use one.
Make call to Rick Shubb or Raul Reynoso at Shubb,or call John Pearse, r maybe Tony Rice - I'm sure any of them would be more than happy to educate you in the proper use of a capo. Or go to a bluegrass festival, watch, and learn.
Your explanation demonstrated, as I expected, improper use of the device. And perhaps you have one, but it's one of the old elastic-band types that are rarely, if ever, used anymore - and those, if just slightly off the back of the fret, might be equivalent to excessive finger pressure and affect your tuning by a nearly inaudible amount. If so, let me know and I'll mail you a modern one with instructions for use. No charge.
The only "common sense deduction" that can be taken from your original statement regarding capos and your explanation is that you do not know how to use one correctly.
Glad we cleared THAT up.
Oh - and to go full circle, I think folks listening to player using a capo cranked down midway between a pair of high-crowned frets would not comment "he's pretty good" - because he'd be out of tune due to misuse of his equipment.