Apparent Depth of field with Canon 20D

snip

" IAE, tho, I suspect it's the proper working of the human eye in play
here....."

--
John McWilliams

That's an interesting idea, John, you may be on to
something there. As you know each human eye is
different, with a unique sweet spot of focus. Too far off
and you need glasses or a dipodic correction to bring
images into ideal focus. For example binoculars have
a built-in adjustment for individual eye focus. Of course
the human eye also has it's own focus mechanism that can
physically squeeze the lens of the eye for ideal focus.
Perhaps when looking through the viewfinder with
abnormal vision the ideal focus was shifted off a little,
resulting in a plane of focus that was different than
perceived by the eye at the eyepiece... I can't say
I have ever noticed this but it seems possible.

Dave