Roger writes:
> Can anyone indicate a source for the OM4Ti that addresses this
> kind of technical information?
I posted lots of data here on the variation in film surface reflectance for a
variety of popular films. And I'm heartened to see Buddy (who also tested his
favorite films) has taken that variation into account with his exposure
practices. I wasn't sure that anyone cared that OTF metering no longer met
the original design assumption of having the film within 1/3 stop of 18%
reflectance. Given the variation that Buddy and I found, it leads to OTF
exposures that are outside tolerance limits for the metering system!
To me, OFT was a fine idea dependent on an assumption that is no longer valid.
When OTF metering was first introduced, one of the American photography
magazines determined that film surface relectance was near to 18 0.000000or all
major types. Today, reflectance is all over the board.
Take home lesson here is to either choose a film that is close to 18%
reflectance, chose one that is off by dial in an exposure compensation, or do
flash photography manually (like I do with my macro work) or with the sensor
in the flash (which assumes 18% average reflectance of ALL the subject
matter).
Gary Reese
Las Vegas, NV
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