It's easy to tell when a polariser is "circular."
Looking thru it from the lens' viewpoint, rotating the filter will
enhance/reduce reflections from glass, water, etc.
Looking thru it from the subject's viewpoint, there is no effect from
rotating the filter.
This is because the Circular Polariser is a sandwich of two layers. The
front is a regular linear polarising filter. The back de-polarises the
light so it will pass thru the OM 4 & 3 semi-mirrors evenly.
Light reflected from non-metallic surfaces is polarised. A polarising
filter will enhance or reduce the light intensity. Rainbows are also
polarised, and polarisers will enhance or reduce their intensity
depending how the filter's turned.
Interestingly, the depolarising layer will improve the accuracy of the
meter, since it won't be mis-measuring light from the subject that
comes thru the lens polarised in one direction or another!
Tom
> Date: Mon, 31 May 1999 19:40:58 GMT
> From: Frank van Lindert <Frank.van.Lindert@xxxxxxx>
> Subject: Re: [OM] Olympus POL filter linear?
>
> On Mon, 31 May 1999 15:49:19 +0200, "Hans van Veluwen"
> <mail@xxxxxxxxxxxxxxxx> wrote:
> >Saturday I aquired a nice priced ($20) used 49mm original Olympus POL
> >filter. Am I correct that these filters are linear, and thus probably not
> >the best partner for the OM-3/4?
> >Hans
>
> Hi Hans.
> If it doesn't explicitly say circular, then it is linear.
> Olympus have only made circular POL's in 49 and 55mm, AFAIK.
> My latest _dealer_ price guide (1997) says they cost $75 and $100,
> respectively (these are net prices in europe).....
> Frank van Lindert
> Utrecht NL
------------------
From: Tom Trottier, President, ACT Productions Inc.
infoanim@xxxxxx http://www.act.ca
+1 613 594-4829 fax +1 613 594-8944
199 Holmwood Ave, Ottawa, Ontario, Canada K1S 2P3
"Make it as simple as possible, but no simpler" - Einstein
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|