Vignetting is a darkening of the corners. Since the spot meter is directly
in the middle of the frame, vignetting can not possibly be the reason for
the meter's inaccuracy.
To answer your question, no, you don't have to compensate. You have to find
another way to take a meter reading. The factory itself says the spot meter
is "unreliable". The word "unreliable" means that there is an element of
chance (luck) involved in using the Spot meter. It may not give the same
result twice and it may not agree with a similar camera. It is not an
accurate way to take a light reading, according to Olympus itself.
In short, what we have learned is "Do not use the spot meter with any focal
length other than 50mm."
Lama
From: "Thomas Müller" <thomu@xxxxxxxxxxxxx>
Thanks to all for your input.
So, it appears to be a systematic problem with wide lenses and spot
meter. I still do not quite understand why the two cameras I tested
behaved differently (the center-weighted and spot reading in my
OM4Ti/2-13 weere identical, but not in OM4/2-4). But, could be.
Vignetting could be a reason for the observed behaviour, but one
fStop difference between center-weighted and Spot reading seems a bit
too much vignetting (I did my test at f5.6).
Be it as it is, question is, can I use the Spot meter with wide angle
lenses at all, do I have to compensate?
Gruesse, thomas
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