i am not sure how hard it is...but my B+W UV filter have multi-resistant coat...which means not so easily scratched...
anyway, the UV filter is very cheap compare with the cost of my Carl Zeiss lens...so it is good to have one to protect it.
I recommend B+W MRC UV filter especially if you are using expensive DC....cos the filter will be on the camera at all time...so it is justify to use the best filter
Oops, found out the price of the uv filter on another site here. Sigh, I think I kena "tok". Bought a "PL" brand UV filter for the oly 3020 at $30.:dunno: I must join one the SEED expeditions someday.