View Full Version : Polarizer

11-10-2003, 02:27 PM
Hi all, I have a question regarding polarizing filters:
I've been always told that with linear polarizes the auto focus won't work, so when I switched from manual to auto/digital I forgot the lin pol and I bought a circular pol.
Now I’m changing from my beloved E-20 to a D-60 and since the lenses has different filter diameters I’m going to buy new filters from my new lenses (mainly for the Canon 17-35).
I've started reading some sites to choose the filter manufacturer and in some sites is advised that for auto focus only cir pol are working in some other sites this is labelled as a "mith".
Since I prefer more the linear pol rather than the c pol and since I don't want to trash money in testing the 2 filters (BIG LENSES !!! ) I’m asking your opinions/experience.

Thanks, Besr Regards.

Sorry for my awfoul english.

11-10-2003, 08:34 PM
What I've heard, and what I've observed tends to make me believe that it's a fact rather than a myth.

Most modern cameras use a beam-splitter to perform AF and exposure duties. Somehow or other (this is the only part I'm a little hazy on) a linear polariser interferes with the function of the beam splitter.

The reason I believe it true then? My DSC-F505V has problems focussing with a linear polariser, and is fine when used in the same situation with a circular one. Couldn't initially work out why the focus was often wrong when I was using the polariser (from my old non-AF camera) then it dawned on me. Buying the circular polariser did improve it, and my testing has proved it (to my satisfaction at least).