Like HowStuffWorks on Facebook!

How UV Filters for Cameras Work


Cool Camera Stuff Image Gallery With a UV filter, those faraway mountains won't fade to white in your photo. See more pictures of cool camera stuff.
EyesWideOpen/Getty Images

Even the most sophisticated camera can't adjust to the nuances of light like the human eye and brain can. That's why it's such a shock when a photo image looks completely different from the image you've retained in your mind. Why does that finely-chiseled backdrop of mountains you admired with your eyes disappear into the off-white haze of the horizon in your photo?

The culprit is UV radiation, which is outside the range of visible light but still can affect photographic images by lowering their overall contrast. Don't despair. You can overcome the problem by using a UV filter. By reducing the amount of UV light, you can capture a photographic image that more closely resembles the image in the light table of your mind. If you're artistically minded, you can use a filter to subtly convey emotion, evoke memories and summon up other feelings that embellish and shape the way we see the world [sources: Sholik, Hoddinott].

When you look through a UV filter, the thin, clear piece of glass inside a plastic or metal ring doesn't seem to block any light at all. That's because you can't see UV, the sort of light that it filters, which has a shorter wavelength than visible light. The filtering occurs at the subatomic level. The particular arrangement of electrons in the atoms that make up the filter allows most frequencies of light to get through. But it hinders part of the UV range, which includes everything below 400 nanometers in wavelength [source: Chemistry Department, Michigan State University].

Some photography blogs and manuals argue that UV filtering isn't really needed as much as it once was, because of advances in both film and digital imaging. But UV filters also perform another valuable function. Because you can leave them on your camera pretty much all of the time, the filter protects your lens from being contaminated with dust or scratched while you're out on a shoot. Unlike a camera lens, which can cost hundreds of dollars, you can buy a UV filter for $20 or less, so it's much more expendable -- though, with a little care, it's fairly durable, as well [source: Hoddinott].

In this article, we'll discuss how UV filters work and which different varieties of UV filters are available, and we'll also give you some tips on how to use them and take care of them.