The ultraviolet (UV) filter is clear & neutral.
Ultra-violet (or UV) radiation is invisible to the human eye, but can be seen by bees and butterflies, and most photographic film and digital camera's sensors are sensitive to it. It is found in the electromagnetic spectrum next to visible blue wavelengths.
Ordinary glass absorbs much of the ultra-violet range, but its longest wavelengths (called the near-UV, because they are near the shortest visible blue wavelengths in the spectrum) can be transmitted through uncoated glass lenses to be recorded on film or on a digital sensor. It actually records on a different focal plane from that of visible light. UV registers on color film as an unsharp, undesirable blue or even as a magenta tint on portions of the image. If the UV is weak, it often can’t be detected in an image, but if it is strong, the out-of-focus ghost image it registers on film or digitally can make a picture look unsharp.
Sunlight contains a good deal of UV radiation, which would normally make it a concern in outdoor photography except that the atmosphere at ground level absorbs so much of it that the UV content of normal daylight is negligible and of little consequence. But, at higher altitudes, where the atmosphere is thinner and absorbs less UV radiation than at lower levels, there is more of it to contend with, making it a particular concern for aerial and alpine photographers. The effects of UV can be exaggerated by atmospheric haze over great distances, which tends to scatter it and make it more pronounced, particularly when looking towards the light.
Many flash units also emit a good deal of ultraviolet light that can cause a picture to be bluer than the scene appeared when photographed. Most manufacturers, however, build an ultraviolet filter into the glass that covers the flash tube (called UV-corrected flash) that absorbs the UV radiation, preventing it from striking the subject.
The skylight filter is a UV filter with a pale rose tinge to it.
THE UV FILTER
Ultra-violet radiation can easily be controlled through the use of a UV or skylight filter that absorbs ultra-violet wavelengths. The UV filter is almost always a clear, neutral filter, having no effect on visible colors, although a pale yellow filter is sometimes also referred to as a UV filter (which it's not). Its use in eliminating the effects of UV radiation is more suitable to black and white photography than to color film.
SKYLIGHT FILTER (THE UV FILTER FOR SLIDE FILM)
The skylight filter is a UV filter with a pale rose tinge to it to warm images up. It is intended for use only with daylight-type color slide films to reduce excess bluishness. It is not needed with color negative film since any excess of blue can be controlled in color prints during the printing process.
BLACK AND WHITE FILM
Even though black and white film can record UV, its effect on black and white images is minimal and not of great concern. When using black and white film, the use of a yellow filter will effectively absorb UV light along with the visible blue.
When shooting in black and white, a yellow filter will effectively absorb UV light along with the visible blue.
IS THERE REALLY A NEED FOR UV FILTERS TODAY?
The answer is yes, even though many modern lenses are coated to screen out UV light waves, making a UV filter redundant. As UV-coated lenses come more and more into use, the UV filter will find less usage, and will only be needed for older, uncoated lenses.
But, because there are so many quality, older lenses in use and there probably will be for a long while (and because not every new lens is UV coated), the UV filter will stick around as a usable accessory.
The UV filter also serves another purpose for many photographers - that of protecting the lens from damage. Click here or on the UV filter as a lens protector link below to learn how. You will also learn how a UV filter can affect your photography with a digital camera.
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