circular polarizer
 

I respect that this is a "darkroom" forum. Where can I ask a question about
a circular polarizer? I checked out alt.photography and well, it's pretty
bad,

Thanks,

Nat

circular polarizer
 

nat spake thus:

I respect that this is a "darkroom" forum. Where can I ask a question about
a circular polarizer? I checked out alt.photography and well, it's pretty
bad,

Try rec.photo.equipment.[plug in your format here].

(Two of the formats are .large-format and .35mm.)


--
Second, Scientologists are like computers trying to run an emulation
of another computer. It can be done, but the performance is awful.
Scientologists are trying to run a bad copy of LRH.

- Keith Henson, from alt.religion.scientology

circular polarizer
 

"nat" wrote in message
...
I respect that this is a "darkroom" forum. Where can I ask
a question about a circular polarizer? I checked out
alt.photography and well, it's pretty bad,

Thanks,

Nat
Probably not quite on-topic here but what is your
question?
Briefly, a circular polarizer is a linear polar filter
with the addition of a "retarder" plate consisting of a
bi-refringent l/4 wave plate. The plate essentially undoes
the polarizing on one side of the filter. This kind of
filter works like a standard linear polarizer but delivers
non-polarized light to whatever follows it. In photography
circular polarizers are necessary for many cameras with
through the lens exposure metering because the metering
system may be sensitive to the polarity of the light coming
in. Most makers of polarizing filters offer both linear and
circular models.
See
http://www.fas.harvard.edu/~scdiroff...arization.html
for a pretty good explanation of how they work.

If you have a polarizer and don't know which type it is,
hold it up to a mirror. A circular polarizer will look gray
on one side and black on the other, a linear polarizer will
look gray on both sides.



--
---
Richard Knoppow
Los Angeles, CA, USA