No actually, it can be done without the mechanism, because even though
you do not know the actual aperture you are using, when you stop down it
gives you a meter reading, and when you are full open, you have another
meter reading. The ratio between the two tells you how much you need to
compensate for when the light changes.
rg
Adam Maas wrote:
That requires a linear aperature mechanism, which only A and later
lenses have (That's one of the major changes between K/M and A lenses)
-Adam
Gonz wrote:
See my earlier post:
"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
Shel Belinkoff wrote:
How might the "green button" be improved?
Shel
[Original Message]
From: Gonz
I'm glad Pentax implemented the green button though of course, but
they could have done a better job of it.
