P3D Notorious Fuji?

["Gary Nored" <gnored@xxxxxxx>]

Karen Obusek writes:


> and Velvia 50 is ISO 32?
> Certainly a little underexposure would saturate color but I think this
> statement is a stretch.

To which I can only say, "yup!" 32 is just about right for Velvia. The last
time I dared to make this assertion I was thoroughly flamed, but I continue
to give this advise to new users of Velvia, and I continue to be thanked for
the suggestion. The problem with ISO numbers is that you can't really use
them as much more than a starting point for determining your own exposure
ratings; moreover, most ISO numbers make film look a little faster than it
really is, presumably because "faster is better."

ISO numbers define the amount of light it takes for films to reach specific
density threshold. But the human visual system does not base its brightness
interpretations on the same criteria. It decides brightness on the basis of
several factors, including shadow-to-highlight ratios, midtone placements,
representation of known values etc. Velvia's response characteristics make
it measure out at ISO 50, but shooting it at that speed makes it difficult
to avoid black eye-sockets, cherry-red caucasian skin tones, pitch black
shadows and exagerated colors in the highlights. Opening up a little tames
most of these problems and makes this emulsion useful in a much wider range
of contexts than would otherwise be possible.

For further confirmation of this figure, check out a few nature photography
magaines. The most common spped figure you will see there is ISO 40. This
represents a 1/3rd stop underexposure from the 32 speed I recommend as a
starting point; nature photographers routinely "underexpose" pictures in
this manner to improve the color saturation.

Fuji isn't playing with the numbers ... but a single number cannot
adequately describe a film's behavior to the full range of tones we
experience in a finished photograph. You have to experiment and then
practice using an emulsion to determine ratings that are useful for your
equipment, your photographic habits, and your preferences.

Now I shall put on my asbestos underwear for surely the flames will
follow...

Gary Nored


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