At 15:38 6/12/02, Tom Trottier wrote:
Different films also cause different auto vs manual exposures on the slower
speeds since they reflect differently. See
http://www.markcassino.com/essays/ttlflash.htm and
An interesting article. It cites a TTL-OTF metering problem I've *never*
encountered with an OM-2S and OM-4, both with and without a T-20, T-32, and
Metz 40MZ-3i (with SCA 321), all in TTL-Auto when using:
Kodachrome 25
Kodachrome 64
Ektachrome 100 EPN
Ektachrome E100S
Ektachrome E100VS
Ektachrome E200
Ektachrome 400X
Ektachrome 64T
Ektachrome 160T
Portra 160 NC
Portra 160 VC
Portra 400 NC
T400CN
TMax 100
TMax 400
TMax P3200 (EI 1600/Push 1)
Tri-X Pan
Fuji Astia
Fuji Provia 100F
Fuji Sensia 400
Fuji Provia 1600 (EI 1600/Push 2)
Agfa Scala 200X
Ilford XP-2
(whew! I think I listed them all)
More seriously, be cautious if doing an experiment with measuring
reflectivity of a film leader. Film emulsion *does* change color when
exposed to daylight, and its reflectivity *will* shift as a result. How
much it does for any particular film I do not know.
I won't make claim there's no difference in emulsion reflectivity as I
haven't measured it, but all botched exposures have *clearly* been my
doing, not the TTL metering system's. Some of these films, such as
Kodachrome, are not very forgiving of exposure error. I make no
compensation for normal lighting conditions! Both the OM-2S and OM-4 seem
to be very robust in center-weighted TTL-OTF unless there's very strong
back-lighting over a fairly large area of the frame with a shaded/shadowed
subject. Must be something wrong with my OM-2S and OM-4 TTL metering.
:-)
-- John
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