"Cyclo" <cyclo@mmic.net> wrote...

Polarizers need approximately 1-1/2 to 2 stops exposure compensation,
usually without regard to rotational orientation or subject matter. Certain
camera optical systems employ internal surfaces that themselves polarize
light.  Using a standard (linear) polarizer will cause the light to be
further absorbed by the internal optics, depending on the relative
orientation.  A Circular Polarizer is a linear one to which has been
added,on the side facing the camera, a quarter wave "retarder."  This
"corkscrews" the plane of polarization, effectively depolarizing it,
eliminating the problem.  The Circular Polarizer otherwise functions in the
same manner

minimum effect? I assume you mean facing the sun - or backlit
situations?

Answer1 - yes - yes because the polarizer no longer does anything for
you when facing the sun - hence, the same as no filter at all - the
idea situation for a CP is having the sun at your back, but you still
get partial effect with the sun at 90 degrees - or at your shoulder. So
it's the same as no filter at all in one respect - nothing is
accomplished.

Answer2 - No - not the same because all filters lose some amount of
stops - not sure how much for a CP loses but they are dark filters so
I'm sure the other poster was close with 1.5 - 2 stops - so it would be
better to not use the CP in that it is accomplishing nothing for you,
and it is lowering the light that gets to the film and less glass is
better than more.

My experience is no...not the same.
rgds
Ken

Try here.  Still argued, but I think you can make the image worse or
better..

http://groups.google.com/group/alt.photography/browse_frm/thread/3722d8b68f0e2c6/