Ultraviolet rays can cause a bluish cast in photos as well as increase the effect of atmospheric haze. The filter blocks ultraviolet rays, which adversely affect both B&W and colour films. It is considered a necessity for the scenic photographer. It can also be left on at all times to protect the lens. BAF - Black matt aluminium satin finish almite frame reduces reflections. LPF: Ultra think low profile frames to help avoid vignette on super wide angle lenses. BRG: Black rimmed glass reduces light reflections around the filter edge. KEF: Equipped with a knurling edge for easy attachment and removal. DVC: Digital multicoated filters greatly reduce lens flare and ghosting caused by reflections. Glass manufactured by AGC Corporation Japan.