i'm currently shooting my exterior landscape photos on program mode, iso 200. on nice, sunny, blue-skied days i'm getting a more "gray" sky than blue. any suggestions on how i can "Blue" up the sky without post editing? i use an xt with a tokina 12-24mm with no filter. i also sometime use my 50mm 1.4 with no filter. do i need filters? if so, what kind?