Wayne Culberson wrote:
>
> > Remember that none of the numbers we use are exact. Film speed varies
> > from batch to batch, with age, with temperature, with length of
> > exposure. Most lenses list their speed as approximate f-stops and say
> > nothing about their actual T (transmission) 'stop'. Less light gets to
> > the lens from a complex lens with many elements than from a simple lens.
>
> I noticed this the other day when trying to get enough light. I took off a
> vivitar short zoom lens, and put on a Zuiko 50/1.8, and gained a full stop
> of shutter speed (both at 50mm obviously, both at same f stop, same scene)
>
> Wayne
>
That may not be different between T-stop and F-stop, it could be the
error (or high tolerance) on third party lens. I found the Tokina
28-70 3.5-4.5 SD is over exposed at least 2/3 stops if I use it in
manual, so for this lens I will stick to auto and use exposure
compensation dial if need. No problem found on other Zuikos (may be
except the 28-48, which also seems to have some problem in this area).
C.H.Ling
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