It reduces UV. To be pedantic, a good brand may reduce UV. In practice, if it's a good brand, it will cut through haze a little (cameras see a little more haze than people do), take away a little blue tinge, and increase contrast. You may or may not observe these effects. It's typically used to protect the front glass, for those who like protecting the glass.
A polarizer is a very different animal, looks very dark, and has a front ring that rotates. It's used for controlling the sky and reflections (see posts passim).
Your filter, if it's the 72mm CF7037UV, retails for $10-$14, it would appear. The DF7037UV is around $16-22. Not to say it's a bad filter, 'cos that's what they all sell for.
Re lens noise, not much at all. I can't listen at the moment because the lens is loaned out.
Last edited by Bushfiva; 5th August 2009 at 09:00.
Reason: Lens noise