Hoya 52mm C2 BLUE COOLING

Hoya 52mm C2 BLUE COOLING

The Hoya 52mm C2 BLUE COOLING is a colour correction filter designed to adjust the white balance of your image. Blue Cooling filters correct reddish and orange casts in shots taken outdoors or indoors under artificial or fluorescent lighting. By reducing red and orange tones, blue tones are indirectly enhanced. Blue Cooling filters are available in the grades C2, C4, C8 and C12, which refer to a mired shift of -20, -40, -80 and -120 respectively. The lower the mired value, the less orange and red light enters 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 worked 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 you need to reduce the mired value by -26. Using this formula, you can calculate which filter is most suitable — in this case, the C2 filter with a mired value of -20 is the best choice.