When buying DC, I often say that I need to take a blank sheet of paper, saying that it is a white balance. What's the use?

First of all, white balance doesn't need much consideration for ordinary photographers. It is recommended to go to the forum to see the shooting effect of your favorite model before purchasing the machine. I think this is much more useful than dry goods data such as ISO, white balance and photometry. Of course, you still have to consider many aspects comprehensively, so I won't go into details here.

The so-called white balance is the restoration of white objects by the camera. When we look at the world with naked eyes, we feel the same color under different light. For example, when the sun rises in the morning, we look at a white object and think it is white. And when we see a white object in the dim light at night, we think it is still white. This is because the human brain has adapted to the color reproduction of objects in different light during its growth after birth. But as a camera, it has no adaptability to human eyes. Under different illumination conditions, due to the imbalance of ccd output, the color of the camera is distorted: the image is either blue or red.

In order to understand white balance, we must understand another important concept: color temperature. The so-called color temperature, in short, is to use Kelvin temperature to quantitatively represent color. When an object is heated to a certain temperature by an electric lamp or the sun, it will emit certain light, which contains not only brightness components, but also color components. The higher the color temperature, the more blue components and the bluer the image. Conversely, the lower the color temperature, the more red components, and the image will be reddish. Therefore, if the light that illuminates an object changes, its reflected color will also change, and this change will be reflected in the camera, which will produce different color reduction phenomena under different light. The following table shows the color temperature under some light.

Color temperature of light source (k)

Candle 2000

Tungsten lamp 2500-3200

Carbon rod lamp 4000-5500

Fluorescent lamp 4500-6500

Daylight (average) 5400

Cloudy sunshine 6500-7000

Cloudy sunshine 12000- 18000

As can be seen from the above, the color temperature varies greatly under different light, which leads to different color reproduction of the camera under different light. In order to solve this problem, all current cameras have the function of white balance correction to compensate different color temperatures, so as to truly restore the color of the subject.

Now all cameras have the functions of automatic white balance and manual white balance. Automatic white balance enables the camera to automatically correct the white balance within a certain color temperature range, which is between 2500 K and 7000 K. Beyond this range, the camera will not be able to automatically correct the color of the shooting picture, so the manual white balance function should be used to correct the white balance.