The front ring rotates with the polarization visible in the viewfinder or on your LCD screen. When shooting on a bright day, this means you can control the “blueness” of the sky as well as having control of how distinct you want the cloud formations. For the outdoor shooter, this filter is a must since it is the only way to make a blue sky bluer.
In addition, when shooting into water or glass, you can minimize or eliminate the reflections often associated with landscape or scenic photography. Therefore, if you’re shooting a store window or inside a museum into a showcase, glass obstructions will no longer be a problem. A polarizer tends to have its maximum effect when used at right angle to the sun. A polarizing filter, along with a UV filter should be a part of everyone’s gear.