Light rays which are reflected by any surface become polarized and Polarizing
Filters are used to select which light rays enter your camera lens. They allow
you to remove unwanted reflections from non-metallic surfaces such as water,
glass etc. They also enable colors to become more saturated and appear clearer,
with better contrast. This effect is often used to increase the contrast and
saturation in blue skies and white clouds.
Polarizers do not affect the overall color balance of a shot. It is important
that you choose the correct version of polarizer for your camera. Many of
today's cameras use semi-silvered mirrors or prisms to split the light entering
the viewfinder in order to calculate exposure and focusing distance. Polarizing
filters can sometimes interact with these items to give unpredictable exposure
It is recommended that you choose a circular polarizer such as this one from
Promaster unless you have a manual focus camera which has no beam splitter. If
you will be using your Polarizing filter on a lens which has a focal length of
28mm or wider (on a 35mm camera), we recommend that you use a Wide Circular
Polarizer to avoid a possible vignette effect.