The term "temperature of light" means, of course, not the real temperature, but the color of light, or otherwise - the color gamut of light, the predominance of red or blue spectra in it.
Why do you need to know
It is important to know about color temperature for those who directly work with light, such as designers and photographers. Like no one else, they can confirm that the right color scheme of light can both completely transform everything (whether it be a person in the frame or an interior) or ruin it.
Perfect black body
The temperature of the light source is measured in degrees Kelvin. It is calculated according to Planck's formula: the temperature at which a completely black body will emit light of the same color tone, this will be the desired value.
Thus, the definition of color temperature occurs by comparing the desired light source with a completely black body. An interesting pattern: the higher the temperature of the latter, the more the blue spectrum prevails in the light.
The easiest way to follow in practice: the color temperature of an incandescent lampwith warm white light - 2700 K, and with a daylight fluorescent lamp - 6000 K. Why? An absolutely black body can be compared to iron, which is heated in a forge. We all remember that a metal that is red-hot, but still at a rather low temperature, has a red light, and the expression "white-hot" is often found in the literature - that is, to a much higher temperature. Similarly, a black body emits light in this order of colors from red, orange and white, and ends in white and blue. That is, the lower the temperature of the light, the warmer it is.
Some values
The visible spectrum of a red-hot body, the same "red-hot" metal, starts from 800 degrees Kelvin. It is a dull, dark red glow. The yellow light of a flame is already twice that temperature, from 1500 to 2000 K. The lamps that are commonly used in filming give out readings of about 3250 degrees. The sun, leaning towards the horizon, shines with a temperature of 3400 K, and the temperature of daylight is almost 5000 K. The color temperature of the flash light is 5500-5600 degrees. Lamps with multilayer phosphor, depending on the bin of light, have indicators from 2700 to 7700 K.
Interesting paradoxes
Thus, the word "temperature" here acts as a color determinant. At first, it will be difficult to get used to the fact that the temperature of a clear blue sky (12,000 K) is ten times (!) Higher than the temperature of the flames of a fire (1200 K). And in the region of the poles the sky is still"warmer" - about 20,000 K! Sunlight temperature fluctuates throughout the day from 3,000 to 7,000 K.
It is also noteworthy that different shades have different luminous intensity, that is, they spread differently. It would be incorrect to cite a candle flame as an example, illuminating only a small fraction of the space around it, and a white LED, which is much brighter, but you can compare two identical yellow and white LEDs. Despite the identical size and power, the yellow LED is dimmer, and the red one illuminates even worse.
Gradations
Often we see shades of the same color. In lighting technology, these are most often white gradations: cold, neutral and warm. In fact, even such slight changes in the nature of the gamma affect an instrument as delicate and precise as the human eye. These shades of white not only convey the color of the illuminated objects differently, but also behave differently in different weather conditions, and the range of their light beam also differs.
All of the above features are taken into account by modern manufacturers when creating certain lighting devices, but to understand the difference with colors, you need to enter one more important parameter.
Color rendition
The light temperature of lamps is not the only thing to know. Another of the fundamental terms in lighting engineering is color rendering. Surely everyone has had to make sure more than once that, depending onlighting, we can perceive the same color in different ways. Yes, the names of colors are just an agreement between people to designate a certain wavelength that we perceive with a certain word. In fact, our eye distinguishes about ten million different shades, but we see most of them in daylight, sunlight. He was accepted as the standard.
Thus, color rendering, or the degree of overall color rendering index, is the correspondence of a light source to a standard or the ability to convey the color of an illuminated object in the same way as in sunlight. Measured in Ra, the term color rendering index is also used - CRI, color rendering index.
The reference has a value of 100 Ra (or CRI), and the lower this value is for a lamp or flashlight, the worse this light conveys the natural shade of the object.
Best Options
Temperature, light, humidity are the most important indicators of comfort in any room, so it is important to choose the right shade for lighting. The temperature of lamps and LED lights with cold white light ranges from 5000 to 7000 K. Cool white, as it is called according to the manufacturer's markings, has a fairly low color rendering index, only about 60-65, that is, in such light the human eye perceives colors differently: perhaps, everyone noticed how everything changes in the "lifeless" pale blue light. However, among all the shades, it has the highest contrast, which means it is indispensable when lighting is required for objects that have a dark color.color (for example, wet asph alt, earth). Another feature is its efficiency at a long distance, so usually the shade "cool white" is used in long-range flashlights (flux range - about 200 m).
Neutral white LED - neutral white - has a temperature ranging from 3700 to 5000 K. Its CRI is about 75, which means that compared to a cold bin, the color rendering is an order of magnitude higher. However, the range of the light beam is lower, so lights with neutral white light have a much shorter distance, but are more comfortable for the eyes.
The temperature of warm light (warm white) is from 2500 to 3700 K. The color perception index is even higher, about 80, but the range is even less than that of a neutral bin. However, warm and neutral shades have an advantage over cold white if lighting is necessary in conditions of high smoke, humidity (rain, fog), as well as under water if there is a suspension in it (for example, in ponds). In such situations, cool white does not illuminate the object itself much more, but the space before it, forming a tube of light.
For diodes
If for incandescent or fluorescent lamps you can stop only at the value of color temperature, then for LEDs it is not enough, therefore the so-called division into bins appeared. In diodes, a predominance of blue (green) or pink shades is possible, so if you need several light sources, you must choose the same characteristics. The division into bins is different for some manufacturers, this shouldtake into account if, for example, in the office, you need to change the lamps.
In progress
Typically, warm shades of light are good for creating a warm, cozy atmosphere. It is used in restaurants, cafes, boutiques, hotel lobbies, and residential areas.
White light is more familiar to the eye, suitable if you need to create a friendly, individual, but at the same time working, not relaxing atmosphere. It is good to read in this light, which is why such lamps are installed in libraries, as well as in shops and office premises.
Neutral white gives the effect of a friendly, safe and welcoming atmosphere. In addition to office space, it is used in showrooms and bookstores.
Cold light creates a clear, clean and productive environment. It is he who is advised for classrooms, supermarkets, hospitals, office space.
Daylight lamps with temperatures up to 5000 K emphasize the colors of objects, the atmosphere in this light appears bright and slightly disturbing. Such lighting would be appropriate in a hospital examination room, gallery, museum and jewelry store, because in these areas it is very important that the human eye perceives objects in their natural light.
Photos & Videos
Knowing the temperature of light is especially important for photographers and cameramen, as well as for people involved in photo and video correction. Since the camera shoots everything in unnatural light in cold lighting, this must be taken into account in further processing.
In the days of film, things were much more complicated. Negative and slide versions were producedonly for shooting in daylight (about 5700 K) or for warm yellow light (2500-2700 K, so-called evening film). Only in this way it was possible to obtain an adequate display of colors, without the use of additional correction or filters.
Masked negative color films were produced already at an average temperature of 4500 K.
Into the digital age
No one shoots film these days. Modern digital cameras have color correction in the settings, it can be either automatic or manual. This feature is called "white balance". It is best to make adjustments while shooting. You can correct it in the finished file, but this often leads to loss of quality, incorrect display of colors, and sometimes noise may appear in the picture. You can edit the color gamut without losing quality only if the file is recorded in digital RAW format (in Nikon cameras - NEF).
