Protects the lens from fingermarks and scratches. Unlike the eye, film (and to a lesser extent, digital) is sensitive to ambient UV, and it shows as a misty cast on distance shots especially in seascapes and mountains The UV HAZE filter absorbs this UV giving a clearer result. It will NOT penetrate visible haze which is atmospheric particles rather than UV. A UV filter is clear. Skylight is similar to UV, but is slightly pink in colour to counteract the blue colour cast which is also evident in conditions of high ambient UV.