The Sigma 82mm EX DG Circular Polarising Filter reduces the glare & reflections from glass & water & other non-metallic surfaces. It deepens blue skies, & saturates the colours. The Sigma circular PL filter is designed to give best performance with AF Cameras. The Sigma wide multi coated circular polarising filter is very thin, so it does not cause vignetting with wide-angle lenses. You can monitor the changes at different angles through the viewfinder as you rotate this filter.