Remove unwanted reflections and increase saturation
Polarisers are universally popular filters and their main use is to eliminate unwanted reflections from surfaces such as water and glass. They also make images appear clearer, with better contrast and increased colour saturation, without altering the overall colour balance. Polarising filters will also darken blue sky and enhance detail in clouds.
Polarisers are available as Linear (PL) and Circular (CPL) and need approximately 2 stops of exposure compensation. Linear Polarisers can cause errors with TTL light meters and auto-focus systems, whereas Circular Polarisers do not. CPL filters are designed specifically for use with auto focus and TTL metering of SLRs.