Tuesday 18 September 2007

UV Filter

UV, skylight and haze filters all block ultraviolet (UV) light to varying degrees. UV filter nomenclature is a bit confusing. The term "UV filter" by itself usually refers to a neutral (untinted) filter blocking the shorter wavelength UV-B (320-280 nm) and UV-C (10-280 nm) bands while letting a good bit of the UV-A (320-400 nm) through. Haze and skylight filters are UV variants that often carry a tint. Haze filters block more UV-A than regular UV filters but also take a bite out of visible blue. Skylight filters also cut some blue but are no more effective in the pesky UV-A band than regular UV filters.

The optical role for UV filters in digital photography relates to an artifact known as "purple fringing". Purple fringing is most commonly seen in digital images but also occurs in film images. It typically appears as a multipixel band of bright purple surrounding the peripheral edges of dark objects cast against a bright background. Central edges are spared. Backlit leaves set against a bright sky are a common purple fringing scenario.

Besides, you can use this filter full time in order to protect the front element of your lens from scratches and dust.

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