> > So, - the question is - is this lens really 5.6
>at the long end and not
>6.7
> > like Tokina says it is? Or am I lucky to get the
...snip...
Actually, I suspect it's the LENS that's reporting the
f-stop incorrectly, and that it's doing it on purpose.
If the lens accurately reported f6.7, all EOS' but
the 1v and 3 would shut off AF. That wouldn't be a
great selling feature for the lens.
------------
And when you change the aperture selector to 6.7 the lens
*has* to stop down because the camera body expects it to
do so (stop down 1/2 a stop).
I just wonder how do these lenses - which are e.g. f6.7
but report f5.6 to camera to keep AF - behave with smaller
aperture settings?
If camera thinks the lens is f5.6 (but in fact is 6.7)
and user stops down say 2 stops, thus to f11, shouldn't
the lens really stop down two stops, thus to f13, to keep
the exposure right?
So all the time the lens would be stopping down half a stop
more than what user/camera asks it to.
Unless:
if the EOS bodies - during shutter release - check the
exposure also AFTER shutting down the aperture then the lenses
actually could use real f-values because the camera body could
compensate the ill-behaviour of the lens by using half a stop
shorter shutter time.
Anyone understand what I mean?
Vesa
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