White Balance: definition and settings

The human eye achieves an impressive dynamic range, automatically adjusting for the lighting conditions so we can see in very bright light as well as in gloomy locations. The eye and brain in partnership can also correct colour casts so that a white piece of paper, for example, is perceived as white, regardless of the ambient light.

Unfortunately, digital cameras are not so clever. They record the scene as they see it, within their limitations. This is why, in tricky lighting conditions, we have to set the white balance to ensure the result we want. It is also why we sometimes have to tell the camera the colour temperature of the light falling onto the scene.

What does this mean? In simple terms, light is made up of the three primary colours − red, green and blue. In theory, an equal intensity of all three produces white light, but in practice these colours are present in different proportions in light from different sources. For example, tungsten-filament lights produce illumination with more red than fluorescent lights, which create greener light. Of course, natural light also varies according to the conditions, so that colours appear warmer (more red) at sunset and cooler (more blue) at midday. This varying proportion of colours can be expressed as the colour temperature, which is measured on the Kelvin scale (more about this shortly).

If you are shooting images in any format other than RAW, the camera will post-process the image to make the colours in the scene as accurate as possible. However, this is not always as easy as it seems − the colour temperature of the light falling onto the scene affects the way the camera sees the colours and, unlike our brains, it does not automatically correct it. For example, with no correction, a white wall photographed under tungsten lighting will appear very yellow, and under a fluorescent light will look very green. This is why all digital EOS cameras have the option to set the white balance to suit the ambient light.

If you shoot RAW files, you have complete control over colour in post-processing, so the white balance need not concern you at the time the exposure is made, although it can be useful to get things close to the final image because this will enable you to properly assess the images you're capturing.

Canon cameras have several white balance settings, and your choice of these depends on the type of light you are shooting in.

All these settings still rely on the camera doing some calculations to obtain the correct colour balance. However, there are two further settings which give you total control.

It is possible to use the Auto White Balance setting for all your shots and let the camera sort out the light, or to select the white balance symbol appropriate to the lighting conditions. However, no matter how good these settings are, they won't produce the perfect white balance in all situations.

Instead, use the following procedure and you will end up with images that are properly white-balanced – but bear in mind that if you're outdoors, the light changes constantly, and you need to repeat the procedure whenever lighting conditions change or you move to a new scene.

You need a sheet of white paper, or a mid-tone grey card. With your scene and lighting arranged, place the paper or card in the scene. Making sure that the white card covers at least the centre circle marked in the viewfinder, take a shot. The autofocus may have trouble focusing on the flat card, so focus on the edge of the card and then recompose, or switch to manual focus.

Next, select Custom WB in the main menu. From the Custom White Balance screen, find and select the image you shot in the previous step. The white balance data from the image will be imported.

Exit the menu, then select Custom White Balance from the white balance settings. The pictures you shoot will now be balanced to your test image.

On the EOS-1 series cameras, the menu is slightly different. Within the Set Custom WB screen there are options to Select image on card (the same as above) or to Record and register WB – this assumes you have not yet captured an image to take a Custom White Balance reading from. If you select the second option, then take a picture, the camera will immediately read the image and set the white balance accordingly.

In 2021, the Canon EOS R3 introduced an additional method of setting a Custom White Balance in Live View, which was then rolled out to the EOS R5 and EOS R6 with firmware updates to v.1.50.

This new procedure reduces the number of steps required and is easier to follow in tricky situations such as when shooting underwater or in tight spaces. As with earlier cameras, it still requires a neutral white balance target.

The first step is to select the Custom White Balance icon in the Quick menu, which you access by pressing the Q button on the back of the camera. On the EOS R3, now press the Set button and use the Quick Control Dial on the back of the camera to select the number (1 to 5) that you want to assign to the white balance setting. On the EOS R5 and EOS R6, omit this step. Then, on all three cameras, point the camera towards your white balance target and press the Delete button. At this point, you'll see the effect of the new white balance setting.

Finally, press the shutter release button to complete the process. The camera will show you a reference image, histogram and confirmation that the Custom WB has been registered.

On the EOS R3, if several Custom White Balance settings have been set and assigned different numbers, you can select the one that you want to use via the White Balance settings in the main menu. Alternatively, select the Custom White Balance icon in the Quick menu, press the Set button, use the Quick Control Dial to select the number (1 to 5), and then press either the Set button or shutter release button.

If you find you still cannot get the perfect colour balance in-camera, then EOS digital cameras from 2003 onwards have a white balance auto bracketing function. This allows you to bracket the white balance setting in the same way that you can bracket exposures. You can select the level of change between the images up to ±3 steps in full-step increments. The images are then recorded in this sequence: 1 = set colour temperature, 2 = cooler/bluer colour, 3 = warmer/redder colour.

With all these options, it is possible to obtain a completely neutral tone in most shooting situations. However, this may not always produce the most attractive images. At a carnival, for example, there is likely to be a diverse mix of light sources − tungsten giving a yellow glow, fluorescent adding some green, and lots of neon lights. Even if you were able to balance all the light sources present, the result could end up looking very clinical and fail to convey the fun, warmth and atmosphere of the show. So do not always assume neutral is best − and don't worry too much about getting white balance spot-on in-camera especially if you are shooting RAW.

If you've set your camera to save JPEGs, the camera applies the white balance settings as it processes the image, before saving it to your memory card. Although you can adjust colour in your image editing software afterwards to some extent, the WB setting is "baked in" and strong colour casts are difficult to remove. By shooting in RAW format, you avoid this in-camera processing, and the image saved on the memory card is exactly as captured by the CMOS sensor. It is then up to you to adjust the white balance in your RAW processing software.

Canon's Digital Photo Professional (DPP) software offers a range of powerful options for doing this. You can use the Click White Balance eyedropper to click on an area of the image that should be white or a neutral grey, and the colours will be adjusted with reference to that; you can use the Colour Temperature slider or specify the colour temperature in degrees Kelvin; you can adjust the Blue-Amber and Magenta-Green balance using sliders. Similar tools are widely available in other RAW processing software.

One of the advantages of shooting RAW files is that you can apply different white balance settings to the image in order to see which give the most natural, or most attractive, results. The original RAW file remains unchanged. This means you can return to the RAW file and try again if the initial results are not what you want, or produce variants of the image with different feel and atmosphere.