How are the values of warm light and cold light divided?

Cold light and warm light are mainly determined by the color temperature of the light source.

cold light means that when the color temperature exceeds 5K, the color is blue, giving people a cold feeling, so it is called cold light.

when the color temperature is below 3K, the light color will be reddish, giving people a warm feeling. So it's called warm light.

The artificial light source was originally an incandescent lamp invented by Edison, which uses blackbody radiation. The incandescent lamp not only radiates 276-29K visible light, but also radiates a lot of infrared rays. This kind of lamp has low luminous efficiency (visible light).

At the beginning of the 2th century, low-pressure mercury vapor was used to irradiate halogen powder with ultraviolet rays during the discharge process, so that the fluorescent powder can emit visible light again. Since most of the electric energy consumed by halogen powder lamps is used to generate ultraviolet rays, the luminous efficiency of halogen powder lamps is much higher than that of incandescent lamps, so it is called electro luminescent.

Extended information:

Method for accurately locating color temperature:

Generally, from 1: noon to 2: pm, in a clear and cloudless sky, without direct sunlight, the standard sunlight is about 52 ~ 55 K; The color temperature of news photography lamp is 32 K; Generally, the color temperature of tungsten lamp, tungsten lamp used by photo studios to take black-and-white photos and ordinary bulb light is about 28 K; Because the color temperature is low, the photos taken in this case will feel yellow after being printed.

The color temperature of ordinary fluorescent lamps is about 72~85K, so the photos taken under fluorescent lamps will be blue.

This is all because the color temperature of the shooting environment is different from the color temperature set by the shooting machine. Generally, it can be adjusted on the printer. However, if there are fluorescent lamps and tungsten lamp in the shooting scene, we call it a mixed light source, which is difficult to adjust.

to sum up, it is very important to consider, set and adjust the color temperature during shooting. Whether you use traditional cameras, digital cameras and video cameras.

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