Fabian Chow wrote:
>
> I have an OM-4. At present, I am wondering whether I should continue using
> my existing two Hoya "ordinary" Polarisers, or purchase the often
> recommended "circular" one (PL-CIR). I believe (even though I can't seem to
> find it in the manual) that the spot metering system that measures through
> the reflex mirror is affected by the conventional polarised light from the
> conventional polarisers. My multi-spotted exposures on slide film so far
> has not brought out any major abnormalities when using the normal
> polarisers. Am I missing something out here? Any ideas anyone? Thanks.
>
> Fabian.
>
Hi Fabian,
You definitely need a circular polarizer to get reliable spot meter
readings. Average metering is also affected in manual mode. Only the OTF
system used for auto is unaffected.
Try a simple experiment: Find a subject with little or no polarized light,
e.g. a lamp. Keep an eye on the exposure indicator while turning
the polarizer. The indicated exposure will vary about one f-stop over a
90 degree turn when using a simple polarizer.
BTW, I think I can even see the variation in the viewfinder. When the
meter reads low the finder is bright and vice versa, as should be expected.
Another matter: You may have circular polarizers without knowing it. Try
combining the two polarizers. Circular polarizers will not have a position
where the combined filters turn black (unless they are placed face to face).
Regards
Lars
--
Lars Haven <mailto:lhaven@xxxxxxxxxxxxx> aka <lhaven@xxxxxxxxxxxx>
"When writing about women, one must dip one's pen in a rainbow"
D. Diderot
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