From: "Giles" <cnocbui@xxxxxxxxxxxxx>
I think too much is being made of OTF. In reality, only relatively
few exposures
utilise OTF - those 1/60th in duration or longer. Those with
shorter exposures have
the exposure based off the shutter curtain prior to the exposure.
My understanding is that OTF always works the same way, real-time,
never "prior to the exposure," regardless of speed.
In fact, I believe that even a 1/60th exposure will get half the
exposure measurement from the shutter curtain, as it takes 1/60th for
the first curtain to open, and 1/60th for the second curtain to close.
Well, I guess you're "sort of" right, in that changes in light that
occur after the second curtain is released will not change the
exposure. Thus if there is a bright light that causes the second
curtain to release 1/2,000th after the first curtain, and that light
goes away after, say, 1/600th of a second, the second curtain isn't
going to stop or slow down to even the exposure across the frame, and
9/10ths of the frame will be underexposed.
I occasionally use memory with OTF, but I agree with Giles that if I
feel the need for memory, I'm more likely to use one or more spots
first.
: Jan Steinman <mailto:jans@xxxxxxxxxxx>
: 19280 Rydman Court, West Linn, OR 97068-1331 USA
: +1.503.635.3229
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