Protects your lens
Crutchfield Customer Review (What's this?)
82mm is quite a bit of surface area for a lens. I bought this with a new lens and saw dust, smudges, and other crud on it in days. A filter will give you peace of mind that this isn't happening on the front element of the lens. Camera's images look good and crisp to me so I never find myself wondering whether the filter is flaring or causing image degradation.