hkr4627@acf4.UUCP (Hedley K. J. Rainnie) (02/20/85)
I have a question about shutter priority. It seems that shutter priority
does require a lot of extra features on both the body and lens, but that
program mode does not. For example, the Nikon FA, a Nikon that includes
shutter speed priority, requires the new line of AI-S lenses (or E-series
lenses) for shutter priority while program mode (at least on the FG) does
not require such a lens.
It seems that program mode is performing both the tasks of altering the
shutter speed and aperture. Perhaps the program cameras first stop down
roughly to the selected aperture and then a shutter measurement is taken,
much as in standard aperture priority. The roughness of the aperture
selection is absorbed by the accurate shutter speed. If the shutter speed
were fixed, the aperture stop down would have to be more accurate. I'm
not at all sure.
Rei Shinozuka
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