Possibly the first time you started to notice white balance is when you picked up your digital camera and came across symbols such as AWB, cloudy, flash, fluorescent on the display when you messed with the controls.
Chances are like many you left the setting on auto white balance (AWB) as your knowledge and experience of this subject was not up to speed. Hence this short article.
Typical camera symbols for white Balance settings:
What is white balance and colour temperature?
|The Kelvin scale (simplified) K
If we saw through the ‘eyes’ of a digital camera we would soon discover that subjects lit under household lamps (tungsten lighting) would appear orange/red, under office lighting (fluorescent strip lamps) green/blue and with flash, blue. This is because the imaging sensor or conventional film can't automatically correct for different coloured light sources. Additionally, early and late times of the day, or when its cloudy or sunny, also have a profound effect on colour despite the sun being a single light source. These changes of hue from warm to cold are represented in the form of a scale brought to the attention in the early 1800’s by a Irish physicist William Thomson, later known as Lord Kelvin. His research into this area led to many uses including that for photography to ensure we have the correct white balance under different lighting conditions, from candle light to a clear blue sky.
Setting white or the grey balance is not a new thing. Videographers and TV crews have always needed to set colour balance, usually manually, especially if several cameras are used for the same scene or actor, otherwise a colour shift would be noticed when cutting from one camera to another.
Film photographers also would consider tungsten balanced film for use for stage plays, internal sets or when using photofloods for portraiture. It was designed specifically for correct colour lighting at approx 2500K, if used in daylight all subjects would have a pronounced blue cast.
Alternatively, to changing film type, you can apply filters in front of your lenses, here is a FLD (fluorescent daylight) mauve filter for correcting strip lighting.
For our DSLR’s we want accurate colour for all our images, we want our whites to be white, not a bluey or browny white. We also know if we have a perfect white, it means all other colours will be accurately displayed too. Colour balance is a global thing.
To achieve this, our cameras have a system where they correct colour either automatically or we can activate presets in the white balance menu such as flash, cloudy, tungsten etc. to match the light source as closely as possible. Internally, all the digital camera is doing is ‘applying’ correction filters. So when you are shooting under household lamps it adds a blue filter which counters the red tone.
Example of ‘Colour Filter’s’ used for cloudy or tungsten lighting conditions to achieve a fresh white:
For dull or cloudy days the image needs to be warmed and under tungsten it needs to be cooled. Without this correction cloudy days take on a blue cast and indoors using household lamps, subjects will appear red or orange.
If you want the best or most accurate white balance it is usually an advantage to take it off AWB and select an appropriate preset or better still if you have time, shoot first a grey or pure white subject under identical lighting, then use this as the source image for the ‘Custom’ white balance feature found on may DSLR’s.
Representation of a white balance selection panel on a DSLR camera monitor. It can be displayed either through the menu or via short cut keys.
I have found as an alternative to AWB is to use the daylight setting for most shots – it appears to produce better colours more of the time and if your particular camera as a problem with colour shifts it normally corrects it in an instant.
If you shoot RAW files you will have the ability to change the white balance after the shot was taken – an absolute boon for serious photographers. You can fiddle to your heart’s content and get the colours just as you like them.
Alternatively, you can use a colour meter to indicate the correct white balance but these can be very expensive. Most meter manufacturers offer one in their range.
Sekonic Colour temperature meter
It is worth getting to know about your white balance so experiment a little and scope it out for yourself. Try all the different settings and see what you think to the changes it makes.
Here are a few examples of its use in real shooting situations:
Here are 11 images of the same Snow Leopard taken recently on one of our Big Cat Experience days. What they show is the dramatic changes in colour that occur by selecting different white balance settings on the camera. Interestingly, If you do not view the cat but concentrate only on the darkest green leaf just to the right of its head it is then difficult to see the colour changes!
The day was slightly overcast so you would imagine that the cloudy setting would be optimum but you may consider it too warm. The most ‘accurate’ colour image is the one where I have taken a reading from a white part of the cat’s coat, labelled white point. This may not necessarily mean it’s the most pleasing to the eye. Which one would you choose and why?
Another factor to consider when viewing these images is the accuracy of the website’s own colour management, your camera, computer display monitor and your interpretation of what is good colour. This is why many photographers are starting to consider more about colour management which is another subject in itself.
Remember, if you are able to shoot RAW you can change the white balance at will afterwards to pick out the best shots for you.
Visit David Hemmings' website
for more details.