Giles writes:
<< How about using spot or multispot metering - which is probably more acurate
anyway -
then activate the memo function to lock the exposure - no wasted exposure.
Or, if you really want centre weighted, switch to manual, meter, recompose
and
shoot.
That's two ways of locking the exposure without wasting film and if it
wasn't for
the off-composition requirement you would have three ways to lock the
exposure.
Come on, how many ways do you want?
Giles >>
I agree, but just for thought, here is what a Pentax list member says about
spot metering: "Well, actually you can meter the spot you want only when its
reflectance is 18ame as standard gray card - because the
meter is so calibrated And therein lies a huge problem. If the spot being
read is not neutral gray, then your reading is guaranteed inacurate. I only
know of one (well 2
actually, one analog, the other digital) spotmeter that is colour linear.
Let us use as an example, you are photographing a scene with a red barn, and
blue sky. Maybe there is a field of green wheat in the forground. There are
no neutral colours to meter. If your meter is a typical cell, then it has a
colour bias. It will not give an accurate reading of anything in the scene.
That red barn will be out by 2 stops if you read it, the blue sky will be
out by at least a stop, and the wheat field will also be inaccurately
exposed. Unfortunately, it is also impossible to predict the bias without
extensive trial and error, metering and photographing a sample of everything
you might want to photograph, and making notes of the colour induced
exposure innacuracy. A daunting task to say the least. Add to that, the fact
that once you have metered a particular spot, you also must decide what zone
it falls into and set the exposure accordingly. I remember seeing an add for
the Olympus OM-4. They were bragging about its ability to take 8 spot
readings and then average it into the "correct" exposure. Only an
advertising executive could have come up with that! Lets take 8 readings
that are inaccurate, then average them together using some arcane algorithm,
and come up with an exposure that is even reasonably close to accurate? I
think not. And having to take a grey card into the field kind of negates the
whole idea of a spot meter, which is to be able to take an accurate reading
of a small portion of the scene from a distance. If you can walk into the
scene and read a grey card, you don't need the spot meter anyway. Far better
to use the center weighted meter that at least has a hope of giving the
correct exposure by the colour value averaging method (red barn + blue sky +
green field = colour neutral exposure).
Bill".
Gee, I wonder how any of us are able to make good images with our OM-2sp &
OM-3's & 4's.
Regards, Paul Connet
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