John Austin wrote:
> They would all be "correct". The purpose of the test was to determine the
> correct ASA/ISO setting to give neutral results with that body. Load a roll
> of your favorite slide film and take pictures of a familiar object. A Kodak
> or McBeth color chart would probably provide the most objective results, but
> is by no means a necessity. Vary each exposure by changing the ASA/ISO
> setting on the camera (yes, you could also just dial in + and - exposure
> compensation). Make sure you keep very accurate records as to which frame
> number was exposed at which ASA/ISO. When the film is developed, carefully
> check the slides to determine which one represents the object correctly.
> That is the ASA/ISO setting that you should always use for THAT particular
> film in THAT particular camera. The test will need to be repeated for each
> camera body you own. A pain, yes, but each body can vary. If you're fussy
> about correct exposure with slide film, it would seem to be a necessary test
> to perform. I don't have the book in front of me, but if I recall correctly,
> it was necessary for John Shaw to rate Velvia at 32, 40, 50, and 80,
> depending on which N*k*n F4 camera body he used. These four different
> settings would all produce exactly the same results. The differences were in
> the camera metering systems. As you pointed out, plus and minus 1/2 stop is
> acceptable accuracy from a repair standpoint. And I imagine that other
> repair persons might not be as meticulous as you are and the differences
> could be even greater. Testing will solve this whole problem.
Ideally the procedure should be done by switching same roll of film
between bodies to eliminate variations in film and processing. This way
only the bodies change.
At a minimum the test shall be performed with films from the same
batch and the films processed together.
Lars Haven <mailto:lhaven@xxxxxxxxxxxxx> aka <lhaven@xxxxxxxxxxxx>
"When writing about women, one must dip one's pen in a rainbow"
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