Marumi CPL 55mm
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   Light rays which are reflected by any surface become
  polarised and polarising filters are used to select which light rays enter
  your camara lens. PL (Linear Polarising) and PL-CIR (Circular Polarising)
  filters have the same effect, but it is important that you choose the correct
  version for your camera. They allow you to remove unwanted reflections from
  non-metallic surfaces such as water, glass etc. They also enable colors to
  become more saturated and appear clearer, with better contrast. This effect
  is often used to increase the contrast and saturation in blue skies and white
  clouds. Marumi`s polarising filters do not affect the overall color balance
  of a shot.  | 
 
How to select the correct Polarising filter:
Many of today`s cameras use semi-silvered mirrors or prisms to split the light
entering the viewfinder in order to calculate exposure and focusing distance.
PL (Linear Polarising) filters can sometimes interact with these items to give
unpredictable exposure or focusing. So we recommend that you choose a PL-CIR
filter unless you have a manual focus camera which has no beam splitter.
                        