Hoya 55mm C12 BLUE COOLING

Hoya 55mm C12 BLUE COOLING

The Hoya 55mm C12 BLUE COOLING is a colour correction filter designed to adjust the white balance of the image. The Blue Cooling filters correct reddish and orange tones when shooting outdoors or indoors under artificial or fluorescent lighting. By reducing red and orange tones, blue tones are indirectly enhanced. The Blue Cooling filters are available in grades C2, C4, C8 and C12 which refer to a mired shift of -20, -40, -80 and -120. The lower the mired value, the less orange and red light penetrates the lens.

Mired, derived from the term Micro Reciprocal Degree, is a unit of measurement used to express colour temperature. The Mired value is calculated using the following formula: Mired = 1,000,000K/T, where K stands for kelvins and T for colour temperature. A calculation example: The actual light condition is 4800K; 1,000,000/4800K = 208.3. Your desired colour temperature is 5500K; 1,000,000/5500K = 182. The difference between the mired values is 26, which means that you must reduce the mired value by -26. With this formula you calculate which filter is suitable, in this case the C2 filter with -20 mired value is the best choice.