White balance
White balance is one of the settings of digital cameras, directly influencing color rendering (except in RAW, but we will come back to that). In 90% of cases, the automatic adjustment works well, but when it does not work you have to act and it's quite simple.
So not to deprive yourself of it! We can't talk about white balance without talking about the temperature of the light. But if you want to skip the next paragraph, you can.
Color temperature
I will, here and voluntarily, make a succinct and operational presentation of the color temperature. If you want to get a more complete approach to color temperature, I recommend reading the Wikipedia article on the subject.
Color temperature (CT) characterizes a light source. It is not the actual temperature of the source (for example the sun or a flash) but the temperature of an ideal black body emitting light only by the effect of heat. It is expressed in degrees Kelvin, denoted K.
For the record: 1 degrees K = 1 degrees Celsius and the conversion formula is x ° K - 273.15 = y ° C.
So, as shown in the image below, a black body heated to around 6500K produces white light. If the temperature is lower the light turns red, otherwise it turns blue.
Color of the radiation of a black body between 800 and 12,200 K, for an observer in daylight D65.
- The sun, at its zenith, produces a light with a temperature of about 5800 K, therefore slightly yellow.
- A candle produces a light with a temperature of about 1850 K, so red / orange.
- An electric arc produces a light with a temperature of about 9000 K, therefore bluish.
The table below represents different color temperatures for common natural and artificial light sources:
TemperatureSource1700 KMatch flame, low pressure sodium lamps (LPS/SOX)1850 KCandle flame, sunset/sunrise2400 KStandard incandescent lamps2550 KSoft white incandescent lamps2700 K"Soft white" compact fluorescent and LED lamps3000 KWarm white compact fluorescent and LED lamps3200 KStudio lamps, photofloods, etc.3350 KStudio "CP" light5000 KHorizon daylight5000 KTubular fluorescent lamps or cool white / daylight
compact fluorescent lamps (CFL)5500 – 6000 KVertical daylight, electronic flash6200 KXenon short-arc lamp6500 KDaylight, overcast6500 – 9500 KLCD or CRT screen15,000 – 27,000 KClear blue poleward sky
White balance
White balance is a setting to compensate for the color temperature of the main light source. Your brain automatically compensates based on different benchmarks and knowledge. So when a room is lit by a wood fire or candles, you don't assume that the walls are yellow or orange, your brain knows the walls are white. It automatically compensates for its white balance.
In a camera, the white balance is adjusted in the "White balance" or "WB" menu.
Default setting is AWB (Auto White Balance). The camera automatically corrects the white balance.
However, it may happen that this correction is not good, the result on the display screen is final, the photos are bluish, orange or even reddish.
In these different cases, you have to take the picture again (except in RAW) by changing the white balance setting. There are, in general, two adjustment modes.
Automatic modes
Automatic modes, represented by fairly obvious pictograms:
Day light5200 KCloudy6000 KShady7000 KIncandescent light3200 KFluorescent light4000 KFlash6000 K
These modes allow you to quickly choose the situation that most closely resembles the context of the shooting.
Manual modes
Manual modes allow you to either choose the color temperature yourself, for example when a light manager on a fashion show gives you the temperature of his spots, or to use a gray chart to determine the color temperature.
Color temperature2000 - 10000 KGray chart2800 - 10000 K
Step by step adjustments
Now let's see how and when to operate to adjust the white balance. Two scenarios arise:
- Either you shoot in RAW
- Either you shoot in JPG (or other image formats)
In RAW
If you're shooting RAW, you don't need to worry about white balance when shooting. When you process your images with your favorite software (Photoshop, Affinity, Lightroom, etc …) you will be able to determine the color temperature and the tint correction.
In JPG
If you shoot in an image format like JPG, you must check your image after shooting. If it is too blue or too orange, you have to change the balance manually to get the correct shade and retake the photo.