There are two schools of thought on having a UV filter on the front of your lens. Some people saying it's definitely worthwhile, as it'll protect the lens, while other people claim it's a waste of time, that the UV filter just serves to provide a false sense of security, and will degrade the quality of your images.

I have always had a UV filter on each of my lenses, to provide some protection to the front lens element from scratches, fingerprints, and other damage.

58mm Hoya UV filter on Canon 100mm f/2.8 macro lens

Earlier this week, the camera bag containing my Canon 350D and 17-85mm IS lens was dropped. I didn't think much of it at the time, and it was only later that I noticed the damage. The UV filter on the front of the lens had completely shattered.

However, after carefully unscrewing the broken UV filter, and using a blower to remove the tiny shards of glass on the front of the lens, an inspection of the lens' front element indicated no damage to the glass element, or to the filter thread on the front of the lens.

The UV filter had protected the lens from any damage. In addition to protecting the glass front element of the lens, the filter also provided protection of the filter thread on the front of the lens. If the glass element had been scratched, it would result in artifacts in any photos taken with that lens, and if the lens' filter thread had been damaged, I wouldn't be able to mount any filters to the front of the lens (ie, circular polarising filter, Cokin Z-Pro ND Grads, etc).

It's much cheaper to replace a UV filter, than it is to replace the front element on a lens! I certainly intend to keep a UV filter on the front of each of my lenses after this incident.

I recently purchased a Cokin Z-Pro U960 ND Grad kit for my camera and some adapter rings, and I'm looking forward to using the filters on my camera.

Cokin Z-Pro U960 ND Grad Kit

mounted on a Canon 10-22mm lens

I wanted the Z-Pro kit primarily so I could use Neutral Density and Neutral Density Graduated filters (often referred to as "ND" and "ND Grad" filters) on my camera.

The purpose of an ND (neutral density) filter is to reduce the amount of light getting to the camera's sensor, without affecting the colour balance, contrast or colour temperature. ND filters are useful for allowing longer shutter speeds to be used (ie, for "smoothing" out water when taking photos of rivers and waterfalls). An ND Grad filter is a graduated ND filter, and has half the filter darkened, and half the filter clear. This allows you to darken a bright sky, to ensure both the sky and the subject are better exposed.