Polarizers are commonly used to control glare on water and to allow the camera to see below the surface. They are also used to reduce glare on car bumpers and to control reflections on plate-glass windows. Polarizers are so versatile that they can perform the opposite functions as well. Some cinematographers use polarizers to increase or enhance reflections, simply by changing the filter’s setting.
There is virtually no limit to the new ways Directors of Photography find to use effective polarizers. Virtually any subject involving glare or reflections, or that is illuminated with specular light, can be improved through the skillful use of a quality polarizing filter.