The neutral protective filter Hoya Pro 1 D is just perfect! It never leaves my goal. As well expresses its name, it is used to protect the front lens against blows (better a broken filter 30/50 euros target), dust, sand, fingerprints and other dirt. I opted for a neutral filter (range 'Protector' in Hoya) as the UV filter is useless on recent objectives already treated anti-UV.