I'm with Sam on the filter thing! I do have clear UV filters for my lenses, but if I use them, it's only for protection, and not while I'm actually shooting pics. I just suck up the annoyance of taking the lenscap off and on and off and on.
If you do use the filter while actually shooting, make sure it's pristine and doesn't have smudges, dust, etc. I have some great cleaning brushes & clothes that I use to make sure my lenses are clean.
Most lenses these days have coatings & UV protection actually built INTO the lens itself, so you don't technically *need* it from an extra filter (at least for shooting at normal non-mountain, non-aerial conditions.) For ME, at least, I find that having the UV lens on there means more dirt & smudges to clean, so I don't use it.
If I had to shoot with water splashing, though, or dust flying, I would probably reconsider...in those situations, I'm sure the UV filter would be a Godsend!