Due to its light pink color, the Hoya Skylight (1B) reduces the bluish cast of daylight and produces a pleasing, warmer picture tone. Wise initial investments, they help protect your lens from dust, moisture and scratches, which can lead to costly repairs. If desired they can be left on at all times for protection. Skylight filters provide additional benefits of correction for Ultraviolet(UV) light which can register on film and videotape as a bluish cast and can obscure distant details. Also used to reduce the bluish cast common with some electronic flash units.