Light rays which are reflected by any surface become polarized and
Promaster 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. Promaster polarizers do not affect the overall color
balance of a shot.
It is important that you choose the correct version of
Promaster 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 or
focusing.
So we recommend that you choose a circular polarizer 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, we recommend that you use a Wide Circular Polarizer to avoid
a possible vignette effect.