Re: Viewing angle> (TECH-3D digest 221)

[T3D Bob Howard <bobh@xxxxxxxxxxxxxxxxxx>]

RE: John B. asks about "twice diagonal" as viewing distance of print. 
This is a rule of thumb I suppose to prevent "grain sniffers" who 
view 8x10 with loupe. I think the 7 lpm for reading distance if based 
on the 1 min of arc.
Canon has stated in their "Lens Book" that 100mm is the lens that 
equals human vision e.g. central attention, most of our field of view 
is awareness until we move our eyes to center on the object of 
interest. The idea of using 85/90/100 mm lenses for 35mm portraiture 
is to force head size at a decent distance to get a good perspective.
Of course modern news shot with 24mm lens three feet away gives hands 
as big as heads if toward camera! BobH


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