UV filter

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See also: UV water disinfection

UV filters are individual compounds or mixtures to prevent ultraviolet (UV) light from coming through. UV filters used in sunscreens to protect skin or in photography to reduce haziness or fogginess created by ultraviolet light.

A UV filter in photography is transparent to visible light, and so can be left on the lens for nearly all shots. UV filters are among the least expensive filters, so many people use them as protection for their lenses, although this may not be effective. See controversy. For this purpose they are preferred over other kinds of filters which are more intrusive, such as neutral density filters.

The UV filter absorbs ultraviolet rays without changing the exposure. With most images, people will not see a difference when a UV filter is used. However, UV filters (in particular filters lacking coating) may introduce flaring and have negative impact on contrast and sharpness, especially when a strong light source is present.