At 06:24 7/7/01, Andrew Fildes asked:
A question occurs. Seeing that circular pols. work with everything and
linear/top pols. are limited, why do the top manufacturers like B+W and
Heliopan continue to make linears? Is it just for economy - they're about
30 heaper - or is there a situation where a linear is actually better?
AndrewF
There are still many cameras that don't need them (circulars), including
all the current high end RF's. A linear has one less piece of glass in it
making it very slightly cleaner for those who have a distaste for puting
anything in front of their lens unless they must. A circular is a linear
with a quarter-wave plate cemented to the back of the polarizing
element. In other words it's two elements in one group. A linear doesn't
have the quarter-wave plate; one element in one group.
Note:
The quarter-wave plate converts the linearly polarized light passing
through the polarizer to circularly polarized light. This is the
equivalent (not identical, but equivalent) of randomly polarized light to a
half-silvered reflex mirror.
-- John
< 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 >
|