Severi
> What am I missing:
What are we missing?
> The magnification of Canon's EF 2.8/100mm macro at 31cm (the closest
focus
> distance) is 0.48, or 1:2.1
No, it is 1:1
Where did you get the 1:2.1 from?
Out of a book or did you calculate it yourself?
If you calculated it, what focal length did you use?
Where did you find the internodal distance (D) information?
(Remember, 31cm if that is a correct quote is from the film plane. It
includes U, V and a bit "D"in between ...)
At a marked 1:1 my Canon 100 gives 1:1 on film: I wasted a shot on an
engineering rule and checked the negatives ;o)
> So what is the point I'm not seeing? Canon macro is supposed to give
1:1 (I
> don't know the english word - ratio?). How can that be possible if
it can focus
> no closer than 31 cm?
It focusses much closer than 31 cm to the entrance pupil.
Bob
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