Hoya 49mm 80C Color Conversion (HMC) Multi-Coated Glass Filter has been discontinued, here are some related products you might like:
The 80 series of filters are blue. They are used to balance daylight film under artificial, tungsten or standard (household) incandescent lighting.
Multicoated to minimise reflection at the filter surfaces which reduces flare and ghosting.
Filter factor 2 (+1 stop)
** 80 Series Colour Conversion Chart **
80A increases colour temperature from 3200-5500 degrees Kelvin (commonly used with 3200K lamps)
80B increases colour temperature from 3400-5500 degrees Kelvin (commonly used with photoflood lamps)
80C increases colour temperature from 3800-5500 degrees Kelvin (commonly used with flashbulbs)
80D increases colour temperature from 4100-5500 degrees Kelvin (commonly used to remove extreme orange or red)