What is white balance?

Most of the time, most of the people set their cameras to automatic white balance and forget about it and sure enough, for most of the people this seems to suffice and they get decent enough pictures to suit their purpose. This is due to the great advances in technology that we seem to have made over the past few years. If you want real control over the kind of pictures that you take, you have to stop relying on technology and what the camera asks you to do. To take pictures where the colour is finely controlled by you and nobody else you have to master some basic techniques. White balance is one of them.

White balance (WB) is the process of balancing the colour in your photographs, so that objects which appear white in person are also white in your photographs. Our eyes are very good at judging what is white under different lighting conditions - like the yellow light emitted from our bulbs at home or the white light emitted from the tube lights we use, but digital cameras often have difficulty in "seeing" under these lighting conditions. Even daylight for that matter changes its colour at different times of the day. You definitely must have noticed that sunlight has a warm glow in the morning and evening which is missing during the day. The sunlight appears quite bright, harsh and white during midday. To understand this better let us figure out what is the difference between warm, cool and neutral tones.

Understanding tones

WARM TONE IN A PHOTOGRAPH

Any photograph that has red or orange tones on it is said to be "warm". This is usually due do some warm light - like a bulb or the evening sunlight falling on the subject.

COOL TONE IN A PHOTOGRAPH

If a photograph has a bluish tint to it, it is said to be "cool". This usually happens if you photograph subjects in shade, away from the sun or after sunset during the evening.

NEUTRAL TONE IN A PHOTOGRAPH

If a photograph is neither warm nor cool, it is said to be neutral. An important point about neutral photographs is that the colours in it are true. They appear to exactly the way they are, in real life.

The color temperature of a light source is the temperature of an ideal black-body radiator that radiates light of comparable hue to that of the light source. Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, manufacturing,astrophysics, horticulture, and other fields. In practice, color temperature is only meaningful for light sources that do in fact correspond somewhat closely to the radiation of some black body, i.e., those on a line from reddish/orange via yellow and more or less white to blueish white; it does not make sense to speak of the color temperature of, e.g., a green or a purple light. Color temperature is conventionally stated in the unit of absolute temperature, the Kelvin, having the unit symbol K.

• Most DSLRs have a colour temperature range of between 2500k and 10000K
• In your camera, the lesser the number (closer to 2500K) the cooler your photograph will be and the larger the number (closer to 10000K), the warmer your photograph will be. Absolutely white light  is measured at 5600K.

In my opinion, pure white light does not exist naturally. It can only be seen from man made light sources like professionally made HMI lights like they use on film sets or from flash(strobes) used in photography or LEDs. Natural light sources always have a tone to them.

How to set white balance on your camera?

There are three ways that you can set white balance on your camera.

1. Auto white balance: As said earlier, auto white balance or AWB gets the job done 90% of the time and in the newer cameras it is pretty accurate or even amazing at times but with the camera set to auto white balance (or AWB) — your photographs can end up looking slightly blue, orange, or even green.
2. Using the built-in settings: This involves figuring out what kind of light your are shooting under and matching it with the appropriate setting in the camera. So if you are shooting in sunlight, you choose the "sunlight" white balance setting on the camera (symbolised by a "sun") and if you are shooting in cloudy lighting conditions, then you use the cloudy settings and so on. This method too works well - but just barely. It is not very accurate and differs between camera brands and models.
3. Using a custom white balance or preset white balance:  This is the most accurate method of making sure that you get an absolutely neutral photograph and true colours.White balance or  setting colour temperature is you telling the camera that under these lighting circumstances which colour it is to assume is “true white". Once you tell the camera that under these lighting circumstances, THIS is white- the camera is smart enough to make the necessary adjustments to render all other colours the way they are.The easiest way of doing this usually involves putting the camera in custom white balance mode and "showing" the camera a white sheet of paper and then taking a picture with it. What this does, is that it tells the camera that  - "this is white" under these lighting conditions. Once the camera understands that, it makes all the other adjustments accordingly and all your colours come out looking just the way they should.  You can use a device like Expodisc too, instead of the paper which will make the results more accurate.

If you shoot RAW, you can also, take your photographs to Adobe Lightroom or Photoshop and make corrections to the colour temperature in these programs. You can watch the video below to understand more about white balance and how to set it correctly. You can also read the articles (links under the video) on how to white your Nikon or Canon specifically.

Important

While understanding white balance can help you avoid these unnatural tones and improve your photos under any lighting condition. It is not a rule that you must have absolutely neutral tones for each and every photograph you take. You might prefer a warm or cool tone and that is perfectly alright. In fact, skin does look better in a slightly warm tone and many photographers deliberately "warm up" their photographs to make their subjects look better.

https://youtu.be/buex57O_Q5U

Also see:

How to  set custom white balance on Canon DSLRs

and

How to set preset white balance on Nikon DSLRs