on 5/1/02 4:48 PM, Winsor Crosby at wincros@xxxxxxxxxxxxx wrote:
>
> Is there even one film that was tested in 1979 that exists unchanged
> today? You might find it interesting to look at this URL:
>
> http://www.markcassino.com/essays/ttlflash.htm , which discusses the
> issue and has a picture of the the different colors and shades of
> unprocessed film. It also mentions a problem with the light color of
> Kodachrome resulting in the underexposure of flash pictures.
>
> I tend to use the spot meter too, but I was concerned about those who
> use the center weighted auto exposure. It would also affect the use
> of TTL flash.
> --
> Winsor Crosby
> Long Beach, California
>
> ?
Remember that the *color* of the film' appearance won't matter if the
meter's sensor cell ("silicon blue cell"?) has a wide range of spectral
sensitivity. The color of the light reflectance of the film surface won't
cause a problem so long as the meter sensor cell is fairly linear across
light wavelengths.
The film surface textures probably make more difference, although unless
someone is consistently experiencing exposures that are off enough to be
noticable it probably doesn't matter. As only slide film would have narrow
enough latitude that 1/3 to 2/3 stops reflectance difference would matter,
the films to test should all be slide films... and if there are problems, we
should be hearing from someone that "Every time I use Velvia on automatic in
my 4T I get consistently dark exposures, and when I bracket the 2/3 over is
the correct exposure." I suppose that would be the appropriate adjustment
anyway... just correct the effective film speed for the reflectance
variance. For a given film, the reflectance should be consistent anyway.
--
Jim Brokaw
OM-1's, -2's, -4's, (no -3's yet) and no OM-oney...
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