Two photos of the same subject showing colour cast and adjustment. The left hand photograph has a strong colour cast from an overhead incandecent light bulb. The second photograph compensates for the cast adjusting to daylight tones.
Colour Casts
Colour casts are caused by the main light source creating a coloured light resulting in an odd colour mix. Common colour casts are a blueish hue created by Tungsten bulbs; greenish/yellow created by fluorescent lights and reddish tinge caused by very hot bulbs or light sources. A whole series of variations of these exist.
We notice these colour casts in the image or on the screen at the back of the camera. They appear odd to us because we don’t see them when we look directly at the same scene. Our eye-brain system compensates for the colour cast in a sophisticated way that cameras cannot.
If you have a colour cast in a picture you can adjust for it in editors like photoshop and others. However, it is better to compensate for these casts in-camera. Then you can get a shot that is ‘daylight adjusted’, reflects the prevailing light conditions or is how you want the shot to come out. In other words you control the colour cast.
White Balance Settings
In modern digital cameras there is a setting group called ‘White Balance’. This normally provides the following settings…
- Auto WB;
- Daylight;
- Shade;
- Cloudy Day;
- Tungsten;
- Fluorescent;
These settings adjust your picture to compensate for a colour cast. White balance controls compensate for colour casts. You choose what you want to control by picking the appropriate setting. However, most digital photographers never use this setting often content to use Auto WB (white balance). The latter setting allows the camera to apply a setting according to its presets. Most digital cameras are pretty good at adjusting for the most common colour casts particularly for standard shots.
Experienced photographers tend to use RAW files – the image-file format that retains all data captured by the camera. RAW files can be adjusted in post-shoot processing to compensate for any colour issues. In this case the auto white balance setting is adequate because it can be adjusted later.
If you use another file format – most commonly .jpg – you should consider taking more control over your white balance. The .jpg format discards much of the data in the image. The reduced data makes later adjustment difficult and limited. To get the best from .jpg you should maintain full colour-control in the camera. This means carefully managing white balance.
The Settings – and some advice
Picking a white balance setting (other than auto) tells the camera what light source you will be working under. The camera has presets for these conditions. Here is an interpretation of these settings and how to use them…
- Auto WB. The camera senses light colour and the type of source. It compensates for you. It is usually effective. Test shots are advisable.
- Daylight – To be used in normal daylight, but intensifies the blueish tones so skies and similar blues are not washed-out.
- Shade – Compensates for the slightly blue cast seen under shady conditions. The setting increases the red tones to warm the shade slightly. This is a good setting to use on cloudy days or under shady conditions. This is a stronger warmth than the ‘cloudy’ setting.
- Cloudy – Warms up the cooler tones under a cloudy sky, but not as much as the Shade setting. It promotes an ‘afternoon’ warmth feeling. It is worth considering using this setting even on a sunny day. The tones tend to flatter most outdoor scenes and flesh colours. Sometimes worth using indoors too – especially in natural light coming indoors.
- Tungsten – Compensates for the reddish tones from indoor tungsten lighting. The setting adds bluish tones which will iron out the reds creating neutral tones.
- Fluorescent – Compensates for the greenish/sickly-yellowish tones created by fluorescent lights. As various fluorescent bulbs produce different types of light be wary of this setting. Sometimes you might get some really unexpected results. Always check your camera screen. It is not reliable with modern fluorescent variations.
- Custom – Allows you to precisely adjust your camera for the prevailing light conditions. You adjust white balance against a neutral grey colour-card. (T0 be the subject of another tutorial).
Practice
Get to know these settings. Understanding colour casts helps you learn to recognise what sort of light you are working with. This helps you appreciate the effects you see in your final picture. It will help you to research lighting methods as you will be familiar with the terms and the actual colours you see.
Practice makes perfect! So take some standard practice shots in different types of light. Keep the shot the same while you try different settings. This will help you see the effects of the different light on the picture.
By Damon Guy (author and Photokonnexion editor)
Damon Guy (Netkonnexion)
See also: Editors ‘Bio’.
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