Polarizers let you deepen and intensify blue skies, achieve vibrant color saturation, reduce or eliminate glare and reflections from non-metallic objects and glass surfaces, and minimize haze in both color and black-and-white photography. They can be rotated to determine the amount of reflection to be removed. Rotate the polarizer to change blue sky densities from light to dark blue. Create dramatic contrast between blue skies and white clouds.
Standard linear polarizers are used with many cameras, while the circular polarizer is used on cameras with beam splitting metering systems commonly found on automatic SLR and autofocus cameras. Check your camera manual for the metering system employed. A circular polarizer can be effectively used with all cameras.
You can, in all cases, see the effect through the filter.