Polarizer-224x120Here's a good video from Dave Dugdale on the what a Circular Polarizer filter can (and can't) do. Polarizers are terrific for very specific conditions -- deepening blue skies, reducing glare on reflective surfaces like water or glass -- but they're less universal than an ND filter (or, as I mention in the guide, a variable ND). Check out the polarizer filter in action, shot with a Canon T2i:

[via FilmmakerIQ]