>Do all Canon EOS lenses pass distance information back to the camera to use
>with flash exposure?
No. See following link.
http://photonotes.org/articles/eos-flash/
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"A combat photographer should be able to make you see the
color of blood in black and white"
David Douglas Duncan
Speaking on why in Vietnam
he worked only in black and white
http://www.hrc.utexas.edu/exhibitions/online/ddd/