UV radiation is invisible to human sight, but in photography it turns out to be disturbing for the image quality. An UV filter is transparen’t to visible light, and so can be left on the lens for nearly all shots. The UV filter absorbs ultraviolet rays without changing the exposure. With most images, most people will not see a difference when a UV filter is used.
UV sensitivity seems to vary from one digital camera to the next, but most digital cameras seem to be substantially less UV-sensitive than film. In fact, few digital cameras are UV-sensitive enough to reap a noticeable optical benefit from UV filtration, even in the most extreme UV conditions-at very high altitude (well over 10,000 feet) or in very long shots over water.
UV Filter reduces unwanted ultra-violet light and haze. Due to its multi-coated feature, it allows nearly full light transmitting into the lens which produces sharper contrast and well balanced color. 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.
UV and skylight filters generally require no exposure compensation, but haze filters may need a small correction. Since uniform coverage of the entire field of view is usually the intent, round UV filters make perfect sense.
Also, UV (Multi-Coated) filter protects your lens from dust, moisture & fingerprints. Actualy, this is the UV Filter most important real function.
Jay Scott explains:
Each CCD pixel has little color filter on it. These are dye filters, not dichroic, so with exposure to light-especially UV-they will gradually fade or discolor. A UV filter might possibly prolong the life of your CCD. I suspect that fading is not an issue until after the camera is obsolete, though, and it’s likely that other components will fail earlier.
More technical information after a test by photo.net:
# The Tiffen Haze-1 is best. It’s a neutral filter so color balance is unaffected.
# Next is the Tiffen 812. Good UV blocking if you also want a warming filter
# The Hoya 81B is very similar to the Tiffen 812.
# The Hoya UV filter comes next, neutral, but with 2 stops of UV blocking.
# The B+W KR1.5 gives about 1.5 stops of UV blocking with slight warming.
# The B+W and Hoya 1B aren’t very good UV blockers. The 1B is slightly warming
And the conclusion of the test is that not everyone wants a warming filter, so the clear winner for a neutral filter that really bocks UV is the Tiffen Haze-1, though the Hoya UV should also be pretty effective.
[tags]uv filter, uv multicoated filter, photo filter, camera protection, camera filter, digital camera filter, hoya, tiffen, tiffen haze[/tags]