Hi there,
Oh My God!!!
Ole, you just quoted the anti-Christ, the devil incarnate, the heretic William Mortensen;-)
"David, with a 450mm lens and 800mm extension the face-lens distance will be about 1030mm - far enough to avoid the "bignose effect". One meter is a reasonable distance to see other people from - it's when you get closer than that, that it looks "wrong"."
How can that be???
All joking aside, the idea of this thread, using shorter lenses for portraits, has me confused. If you use a shorter lens, you have to move in closer to get the same composition. If you do that, the focus spread is greater and you have to use an even smaller aperture to get the needed depth, then longer exposure and/or brighter lighting, both uncomfortable for the sitter.
300mm lens eyes=100%, nose=90%, ears=120%=30%
600mm lens eyes=100%, nose=95%, ears=110%=15%
The longer lens uses a wider aperture, lower lighting, more comfortable for the sitter. I think the antiques knew what they were doing when they made and used the extremely large 'brass cannons'. Slightly longer than normal still makes more sense to me.
Just a thought.