Originally posted by disconnekt UV filters are are mainly used when shooting film, not really usefull on digital that much (if at all).
I have never used UV filters for their intended (or advertised) purpose - even with film. I shot test scenes with and without and couldn't see any difference in normal use. However, I alway use a UV filter on all my lenses for the aforementioned reason of lens protection. I am sure to use filters with good coatings, and haven't seen any excessive flaring from such filters, though it can happen.
Each time a lens is cleaned, its front coating can incur small microscratches, especially if grit has been transferred to the lens. Over time, these are additive and can contribute to a degradation of the lens. Of course, there have to be quite few lens cleanings to have this happen. With a filter in place, it's not only easier to clean the flat surface, but if it becomes degraded, it can be easily replaced. It also serves as impact prevention and has saved my front lens element on a couple of occasions.
To sum up, film or digital makes no difference since it isn't the optical effect I'm after, but rather the mechanical use of giving a longer life to the lens behind it. If it does block UV, that's just icing on the cake.