Is it mandatory to put UV filters on every single lens? i just bought a Sony 50mm SAL50M28 and was wondering if i needed to put UV filter on it. heres a link to it: http://www.sonystyle.ca/commerce/se...Id=1002947&navigationPath=32090n100269n100356 All my other lenses Sigma 28-200mm , Sigma 10-20mm, Sony 17-35mm have UV filters for protection. But since the 50mm lens is deep down inside the body, is there a need to put one? Thanks!