Why? Because 99.99 percent of all viewers are not aware of... nor do they care about... what distance the photographer intended them to view their photos. It's not about what you're "missing" in your photos. It's about not "connecting" with everyone else and "accepting" that they don't "analyze" perspective as you do. They see what they see and feel what they feel. In the grand scheme of things, this is all that matters.
Then why do you bother applying the principle?
Originally Posted by Old-N-Feeble
Don't forget to consider head/camera positioning which can either enhance or subdue particular features. Also, don't forget to consider the feel of the final image. It's a combination of subject, distance and desired final effect. I do have a rule of thumb for "very" tight head shots though... I quadruple the diagonal of the usable film size. For 135, if cropped to 8x10, the diagonal is about 38mm so I'd probably use something near 150mm. But this is if I'm actually cropping the hair out of the frame right to the face. If I'm including all the hair and a bit of shoulder (straight on and not to the arms) then I might start with a 105mm. These are just averages... for me. A long nose or chin requires different posing and lenses... subdue those features by shooting them straight on with longer lenses... or accentuate those same features, as one would when "characterizing" someone like Jay Leno, by doing the opposite.
Mark Barendt, Beaverton, OR
"We do not see things the way they are. We see things the way we are." Ana´s Nin