http://forums.dpreview.com/forums/read.asp...message=5664775
"My 10D + 70-200IS backfocuses about 8 units (in green or white light - which is a mix of 3 wavelengths R-G-B on LCD), so relative to this "zero", the focusing offsets for different wavelengths are:
Red=-8
Green=0
Blue=+8 "
(where a unit is one tick in the ruler he uses). Check out the thread. It's interesting, except for the moron/troll factor that is so prevalent in dpreview forums.



