UV filters are probably the most common filters used. Not because they are necessary, but because they protect the lens from scratches and whatnot. Let’s face facts; it’s far cheaper to replace a $5 filter than to replace a $300 lens, now isn’t it? UV filters DO, in fact, serve a purpose.
The first thing you have to understand is what UV light is and why you would even WANT to block it. Most of us know that UV light is what causes sunburns and suntans. We know that we use sun screen to block UVA and UVB light. Well that knowledge is great, and immensely important for your health, and the health of your skin, but it doesn’t do you a lick of good as a photographer, now does it?
Light is actually a spectrum of colors. It runs from red, to violet (anyone remember the “ROY G BIV” acronym from school?). Red has the longest wave lengths, and violet has the shortest. Anything that has a longer wavelength than red is called “infrared” and anything that has a wavelength shorter than violet is called “ultra violet.” When it comes to color film, you must realize that color film works because it has different layers, each of which is sensitive to a different color of light. On the blue level, with a lot of ultra violet light, that level gets more exposure, and the photo takes on a distinctly bluish tint.
Now in reality, there is not a lot of UV light at or near sea level. Most of the UV light has been scattered by the atmosphere. At higher altitudes, UV light may be more of a problem, and using a UV filter will help to eliminate a bluish cast on your photos.
The fact of the matter is, at average altitudes, a UV filter might help some, but it won’t hurt anything. It will help to protect your lenses though, so I guess to make a long story short, it would be a wise investment to go out and buy a UV filter to fit all of your lenses, and keep it on the lens at all times; as long as you are aware that the UV filter will be unlikely to actually change your pictures much, if at all. Always remember that no filter is a quick fix for serious errors!