Wiliam wrote:
> I am affraid there is more bad news to add to the good news. I believe
> Polarisers can only handle refelections from non-metallic
> surfaces. I have
> no idea however why this is so.
>
Just to clarify (hopefully) what I said on this subject yesterday. A
metallic (electrically conductive) surface does not alter the polarisation
of the incident light, this has to do with the free electrons in a
conductor. OTOH a dielectric substance (glass, plastic, etc.) will alter
the polarisation of the incident light. When unpolarised light is incident
on a dielectric surface it will be reflected with some degree of
polarisation the amount of polarisation being dependent on the dialectic
properties of the material and the angle of incidence.
So what might be the benefit of using polarised light to photograph metal
surfaces ? If the incident light is polarised in the same direction as the
polariser over the lens then most of the light from that source (T10 ?) will
reach the film, excluding to a large extent any extraneous light from other
sources. If the incident light is polarised at 90 degrees to the polariser
over the lens then very little of the incident light will reach the film but
the same amount of extraneous light will reach the film as previously.
HTH ?
Wayne Harridge
Ivanhoe, Victoria, Australia
http://www.geocities.com/wayneharridge/
< 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 >
|