Colour Temperature & White Balance

We recognise colours for what they are regardless of the lighting conditions, but different kinds of light have different colours or 'colour temperature' - describes the proportion of primary colours (RGB) that exist in a particular light source. High colour temperature light contains more blue while low colour temperature light contains more red. Digital cameras make automatic adjustments to the red, blue & green in order that the image appears more natural, using the white in the subject as the basis for the adjustment. This is handled by the automatic white balance (AWB) setting mostly, but manual options are available to provide better control.

- paraphrased from Hedgecoe & Canon camera manual

AWB

Tungsten

Ordinary bulbs tend to give an orange glow to a shot - the second shot was taken with the WB set to Tungsten to compensate for this. Not sure if I prefer this or not (looks a bit green to me) but you can see what's going on. Both images 1/25s, f/5.6, ISO 400.