Colour is a surprisingly complex topic in photography. Different light sources (e.g. candle light, direct sunlight, street lighting, etc) create lights of different colours. Our eyes and brain normally correct this for us so we don’t usually notice this effect (although you can think of the difference between the very harsh white or blue light from street lights compared to the much yellower and warmer light from a candle). For a camera to make the same corrections it needs to make some assumptions about the light source, and these assumptions are labelled “white balance”.
A DSLR camera will by default try to automatically find the white balance. If it gets this wrong it can result in photographs that are tinted yellow or blue. This means that parts of the image that in reality are pure white will instead appear slightly yellow or blue. The images below show the dramatic effects that changing colour temperature can have on the appearance of an image.
In truth, choosing the best white balance to use is partly an artistic choice. However, there should exist a white balance setting that will make the image appear natural, as our eyes would see the scene. As mentioned before, this white balance setting depends on the source of the lighting in the image. Outdoors this will usually be the sky – either the Sun on a clear day or clouds on an overcast day (the clouds don’t create light, but they do reflect and scatter light, so we can think of them as a light source). At night the source is usually artificial lighting – perhaps candles, a street light, neon lighting, or an incandescent bulb. Indoors we may have shade, lamps, or fluorescent lighting. We may also use a light source from the camera itself, the flash.
These light sources differ in their colour temperature. A source with a higher colour temperature will create light tinted green or blue, and one with a lower temperature will create more yellow or red light. The table below gives some common light sources and their light temperatures (colour temperature is measured in Kelvin (K), where 0°K = -273C = -460F). Be aware that colour temperature is not very closely related to the actual temperature. We may feel colder on an overcast day, but you will find that the colour temperature from clouds is actually higher than that from midday sunlight.
|Light Source||Colour Temperature||Colour|
|Incandescent Light Bulb||
|Morning or evening sunlight||
Although cameras usually have some facility to automatically guess which white balance settings to use, they usually also have some pre-set white balance modes that you can manually apply. On a typical camera you may find the settings listed below.
- Incandescent. This setting will apply a colour temperature around 3000K. This temperature is useful when shooting indoor areas lit by incandescent light bulbs. This setting will also work for newer LED bulbs, as they have a similar colour temperature to the older incandescent bulbs.
- Fluorescent. Sets a colour temperature slightly higher than incandescent mode, at around 4000K. This setting can be used for indoor areas lit by fluorescent tube lighting, such as offices.
- Direct Sunlight. Applies a colour temperate around 5500K, and can be used outdoors on sunny days.
- Overcast. This setting is useful for outdoor photography on cloudy or overcast days. Applies a colour temperate around 6000K.
- Shade. Good for photography in shady conditions, for example indoors with no artificial lighting. Applies a colour temperate around 7000K.
When reviewing and editing photograph you will normally view it on a computer monitor. It is important to be aware that computer monitors have their own colour settings, and this can vary from one monitor to another. As a result, the colours you see on your monitor may not be the same colours that someone else with a different monitor will see. You can get around this problem by correctly calibrating your display, something that can be done with a specialised piece of equipment called a colorimeter.
If you do have a correctly calibrated display (or even if not, but you are feeling brave…) then you can manually adjust the white balance in post processing. To correct a yellow tint you need to increase the temperature, and to correct a blueish tint you need to decrease the temperature. This is normally something that can be done quite easily, but obviously the exact process depends on the software you use. If you do want to play around with white balance I also recommend shooting in RAW format, as this strips out the cameras automatic attempts at setting the white balance and leaves it entirely up to you.
Beyond the technical understanding of what white balance is and how to set it in your camera, it is also possible to use the white balance creatively. Typically we perceive lower colour temperatures as warmer, softer and happier tones, while higher colour temperatures can appear cold, hard and more distant. Compare the warmth of the two photographs below – the only difference is in the colour temperature.
Once you know the correct white balance for the light conditions you are photographing in you can start to be creative by adjusting the white balance to be slightly lower or higher. Alternatively you may find it easier to do this in post processing once you start shooting in RAW.