Safeguard your lens and absorb UV light. Film and video are more sensitive to UV light than our eyes are. This often shows up as a bluish cast in images, especially shots from high altitudes and long distances, particularly over water. The pink cast of the filter gives a slight warming effect for more pleasing images. Tiffen filters are manufactured using ColorCore technology, a closely guarded proprietary process that entails permanently laminating the filter material in between two pieces of optical glass that are ground flat to tolerances of a ten-thousandth of an inch, then mounting them in precision metal rings. The ColorCore process allows us to control the color and density of Tiffen filters, and the characteristics of special effects filters with much greater accuracy than typical dyed-in-the-mass filters, which usually exhibit color and density .