Light rays which are reflected by any surface become polarised and polarising filters are used to select which light rays enter your camara lens.  They allow you to remove unwanted reflections from non-metallic surfaces such as water, glass etc. They also saturate colors and increase contrast and are threaded on both -sides. -Creates dramatic sky/cloud contrast. -Saturates colors without changing color balance. Mount rotates to control amount of effect. Increases contrast equally well with black & white film.

Creates dramatic sky/cloud contrast.