UV filter

UV filter (actually UV blocking filter ) are in photography special filters that block ultraviolet light. You see clear or very weak from yellowish colored.

Application

Photographic film, but also the sensors of digital cameras (such as CCD) are not only sensitive to the visible spectrum of light, but also for the invisible ultraviolet content. The UV light can have two disturbing effects when photographing essentially:

• Conventional camera lenses are corrected only for a certain range of visible light, a high percentage of UV light due to chromatic aberration lead to blur;
• Sunlight is scattered by the molecules of the air, is the maximum intensity of the scattered light in the UV range ( Rayleigh scattering). This particular " blue -heavy " scattered light (see picture) can cause a bluish cast in color films.

Through the use of UV blocking filters, these effects can be effectively suppressed, the photographs become more contrast and sharpness and color errors. A correction of the exposure settings is not required for UV - blocking filters.

In modern cameras with the multi-element, coated lenses, the use of these filters is not required because the total thickness of the glass of the lenses ultraviolet blocking radiation already sufficient. If any other color filter or a polarizing filter is used, an additional UV filter is redundant and only reduces the imaging performance of the lens.

Many photographers see the main task of a UV blocking filter therefore is (similar to the skylight ) in the protection of the lens against mechanical damage, especially scratches as a filter to replace not only easier than the front lens of an objective, but also much cheaper. However, UV - cut filter, like all optical converter lenses, the disadvantage that they can reflect back into the lens and thus lead to unsightly spots of light for backlit light that is reflected from the front lens. To protect the front lens therefore Lens hoods are more suitable.