I've been coming across a bunch of wierd "advice" regarding exposure these
days. I guess it's because I've been reading. People get pretty crazy
regarding how they "rate" their films. "I always shoot Velvia at ASA
32..." for instance. Or how about this gem (figuritive): "I rate TMax 400
at 200 and exposure compensate -1 stop to prevent the highlights from going."
I had gotten sucked into the compensation war years ago by rating K-64 at
100 and Kodacolor 100 at 200. One day I realized that my images were flat,
lifeless and dull. I thought that I'd try actually using the film at the
rated speed. My meters were calibrated so I knew that there wasn't any
problems with my cameras. Fifteen years later I still use the
manufacturers ratings with excellent results. Sure, I've adjusted Velvia
at times, but it has been more because of subject contrast than film.
In the B&W world I am finding exposure techniques that are downright scary.
Most advice I've seen says to underrate the film by as much as a whole
stop (overexposing the film). But in the same breath they recognize that
grain size is best when underexposed so it becomes extremely important to
meter your zone 1-2 for your minimum exposure. Even "Saint Adams" proposed
this same thought process--probably originating it for everybody else to
follow.
My technique is to "know your film." Probably the biggest reason why I
have yet to break from my Velvia/Provia usage and go Kodak which changes
Ektachrome emulsions about as often as a hillbilly buys chew. Know the
exposure latitude of the film and know exactly where shadow detail is lost
and where the highlights burn out. Instead of playing games with film
speed ratings, I exposure compensate based on the scene being photographed.
Cameras with metering systems such as the OM-4/4T make this really easy.
In manual mode, spot meter your darkest subject that you wish to retain
detail in and the brightest. Adjust the aperature/shutter speed until the
two dots are within the exposure latitude of the film. Of course this
technique works best with print films, as slide films really require
middle-toned subjects to be exposed properly. In addition to the two spot
meter readings of the extremes, you might also want to spot meter a middle
toned object for reference purposes to make sure it doesn't get too far out
of kilter.
Film speed ratings are based on "averaging" meters and average subjects.
Before automatically compensating the film speed in all of our
cameras/meters we must determine if it is our metering technique that is
the culprit. When going from one metering system to another do you rate
the film differently?
Ken Norton
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