The Hoya range of high-grade filters have coatings applied to both surfaces to suppress reflection and increase light transmission. There are a few exceptions in the special effects range which, due to the special materials used in construction, do not have coatings applied.
Absorbs the ultraviolet rays which often makes outdoor photographs hazy and indistinct. A multi-purpose fine-weather filter for color as well as black and white films. Also serves as a permanent lens protector.