J. C. O'Connell wrote:
Secondly while its true stop down metering CAN BE more accurate
in sufficient light but if the tolerances of the lens apertures
are kept within design parameters and the cam sensor as well , the wide
open metering can work with more than enough accuracy for even
narrow latitude slide films. That is why the entire photo industry
abandoned stop down metering about 30 years ago. Think about this
if stop down meter is "better" than why doesn't the camera stop
down meter with A, F, and FA lenses too with no open aperture
option?
Its done for convenience. You can see your shutter speed real time and
can make adjustments if its too fast/slow. Pentax could have had a
pseudo-AE mode if they wanted to with just one press of the green button
per aperture selection if they wanted to. By taking two measurements,
one wide open, one with the aperture down, a simple ratio could be used
for all future calculations using the future wide open measurement. If
you changed the aperture, you pressed the green button again.
rg
