What is the color temperature of the light source?

Color temperature (colo(u)r temperature) is a measure of light color of light source, and the unit is K (Kelvin). Color temperature represents the most common index of spectral quality of light source. Color temperature is defined as absolute black body. When the radiation of the light source is exactly the same as that of the absolute blackbody in the visible region, the temperature of the blackbody is called the color temperature of the light source. Low color temperature light source is characterized by relatively more red radiation in energy distribution, which is usually called "warm light"; After the color temperature rises, the proportion of blue radiation in the energy distribution increases, which is usually called "cold light". The color temperature of some common light sources is: standard candle light is 1930K (Kelvin-day); Tungsten lamp 2760-2900K；; The fluorescent lamp is 3000 k; Flash 3800 k; The sunshine at noon is 5400 k; Electronic flash 6000 k; The blue sky is 12000- 18000K.

How to accurately locate the color temperature? This requires the use of a "color temperature table". Under normal circumstances, from noon 10 to 2 pm, when there is no cloud and direct sunlight in clear Wan Li, the standard sunlight is about 5200 ~ 5500 K, and the color temperature of news photography lamp is 3200 K; ; Generally, the color temperature of tungsten lamp and ordinary bulb lamps used in tungsten lamp and photo studios to take black and white photos is around 2800 K; ; Because of the low color temperature, the photos taken in this case will feel yellow after printing. The color temperature of ordinary fluorescent lamps is about 7200~8500 K, so the photos taken under fluorescent lamps will be cyan. This is because the color temperature of the shooting environment and the color temperature set by the shooting machine are different. Generally, it can be adjusted on the printer. But if there are fluorescent lights and tungsten lamp in the shooting scene, we become a mixed light source, and this film is difficult to adjust.