To understand fully, you first need to know that different light sources have different colours. This is called colour temperature.
For the time being you need only know the basics of colour temperature.
1. Daylight or flash has a colour temperature of around 5500K (Kelvins). This is what your camera will be set to if you choose to shoot in daylight WB and will give accurate results when shooting in bright sunlight or under flash.
2. Light with low colour temperatures will give a red/orange/yellow colour cast.
3. Any light with higher colour temperatures will give progressively bluer casts.
4. You can combat the effects of colour temperature using filters on your camera or simply by amending your camera settings.
Tip: when shooting in conditions where you cant be absolutely sure of the appropriate white balance setting, always shoot in RAW format; this will give you the ability to amend your settings in post-process.
A few basic colour temperatures are shown below together with the effects that the light would have on daylight white balance.
Tungsten lamp: 3200K (orange/yellow tint)
Sunrise: 3800K (yellow tint)
Daylight: 5500K (no colour cast; accurate)
Overcast sky: 7000K (light blue tint)
Clear blue sky: 12000K (darker blue tint)
So how to combat the casts?
Well, this is where your white balance settings come in. Let’s take a look at the pre programmed settings:
Auto:
This setting will let the camera assess the scene and choose the appropriate setting. Generally results will be good but don’t rely on it.Tunsgten:
Used when shooting under normal light bulbs (tungsten). This setting will combat the orange/yellow hues.Fluorescent:
Fluorescent light is green/blue in colour. This setting will compensate for this.Daylight:
Use this setting in good daylight conditions.Cloudy:
Cloudy days can create slightly clue casts. This setting will make your colours more accurate in cloud.Flash:
This setting makes the image slightly more yellow to combat the slight blue cast created by flash.Shade:
Light in shade will be bluer in colour. This settingups the yellow to combat this.These pre-sets should give you fairly accurate results, but most DSLRs will give you the option to use a custom white balance setting.
To do this you will need to ‘show’ your camera something white so it can take a reading and decide what colour temperature to set to. You can buy white balance cards which can be used specifically for this task or alternatively, choose something else that is white.
Example:
This test is performed under tungsten (normal light bulb) light using a Canon EOS 5D:
Step 1:
Set your camera to AWB (Auto white balance) and take a photograph.
As we can see, the image has a yellow cast to it from the tungsten light.
Step 2:
Get something white (I’ve used a piece of white copy paper). Compose your image so the ‘white’ covers most of the frame (the spot metering circle must be covered). Capture the photograph. This will be used as the cameras reference point.
Step 3:
Go into your Menu and select Custom WB and press SET.
Step 4:
Select the image of your white card and press SET. The image’s white balance data will be imported and the menu will reappear with a message telling you to set your white balance to the custom setting.
Step 5:
Exit the menu, then press the AF*WB button then turn your dial to select
(custom white balance setting)
Step 6:
Retake your original photograph and you should find your colour rendition is more accurate.
NOTE: If your white test image is under or over exposed, you may not get accurate results.
So that’s it for now. Have a look through your camera’s manual to familiarise yourself with the white balance functions and give it a go.
