UV filter
- See also: UV water disinfection
UV filters are individual compounds or mixtures to prevent ultraviolet (UV) light from getting through. UV filters are used in sunscreens to protect skin or in photography to reduce the level of ultraviolet light that strikes the recording medium.
A typical UV filter in photography is transparent to visible light while filtering out shorter ultraviolet wavelengths. Historically, some photographic films were sensitive to UV light, which caused haziness or fogginess, particularly with a blue hue. However, newer photographic film and digital cameras are highly insensitive to UV wavelengths. UV filters are sometimes referred to as L37 or L39 filters, depending on the wavelength of light that they filter out; an L37 filter removes ultraviolet light with a wavelength shorter than 370nm, whereas an L39 filter eliminates light with a wavelength shorter than 390nm.
Many photographers still use UV filters as protection for their lenses, due to their low cost and lack of effect on the exposure of the shot. However, UV filters (in particular filters lacking optical coating) may introduce lens flare and have an adverse impact on contrast and sharpness, especially when a strong light source is present.[1]
[edit] See also
[edit] References
- ^ Thom Hogan. "Filtration 101". bythom.com. http://www.bythom.com/filters.htm. Retrieved 13 October 2009. However, in photography, the term "UV filter" can be also mean a filter that passes UV light while blocking other wavelengths in the light spectrum, in the same way the term "IR filter" is used. The is a very rare and specialized area in photography.
[edit] External links
- Analysis of Camera Filters | Camera Filters.biz
- UV filters test - Description of the results and summary - Lenstip.com
- UV filters test - supplement - Introduction - Lenstip.com
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