CPL Filters

A polarizing filter (also known as camera polarizer lens, CPL filter), used for both color and black-and-white photography, is colorless and does not affect color balance, but filters out light with a particular direction of polarisation. The polarizer reduces oblique reflections from non-metallic surfaces, darkens the sky in color photography (in monochrome photography color filters are more effective), and saturates the image more by eliminating unwanted reflections. Linear polarising filters, while effective, can interfere with metering and auto-focus mechanisms when mirrors or beam-splitters are in the light path, as in the digital single-lens reflex camera; a circular polarizer is also effective and does not affect metering or auto-focus.