The hoya 81 series of filters controls the bluish coloration that affects daylight film they can also remove excessive blue from the effects of electronic flash the hoya hmc 81a filter is a light balancing filter used to decrease the colour temperature slightly for a warmer redder tone multicoated to minimize reflection at the filter surfaces which reduces flare and ghosting good for general scenics when the photographer wishes to remove the bluish cast from open shade or just add w