The 80 series of filters are blue they are used to balance daylight film under artificial tungsten or standard household incandescent lighting this filter measures 130 x 170mm and only fits the cokin x pro series holder filter factor 2 1 stop 80 series color conversion chart 80a increases color temperature from 3200 5500 degrees kelvin commonly used with 3200k lamps 80b increases color temperature from 3400 5500 degrees kelvin commonly used with photoflood lamps 80c increases c