Light, Science & Magic, 4th edition. By Fil Hunter, Steven Biver, Paul Fuqua.
Published by Focal Press, Taylor & Francis Group.
Further reading:
Basics Photography 02 Lighting, 07 Exposure. By David Prakel.
03 Capturing Colour by Phil Malpas. Published by AVA Publishing.
Normal un-coloured light will appear through our eyes to be white.
Light is in fact made up of a range a colours which can be seen through a prism or in a rainbow. All of which mixed together makes white as we see it. The three primary colours of light that can between them make up the full spectrum of colours are Red, Green, Blue (RGB) as used by monitor screens, digital cameras and even our own eyes.
In photography white light is described using a colour temperature scale called Kelvin. The idea is that a substance heated in a vacuum changes colour the hotter it gets, starting from a dark red at it’s coolest moving through yellow, white to blue at it’s hottest.
Kodak, set the bench-mark for early colour film photography by choosing the kelvin temperature measurement of 5500 as a standard white balance for daylight film. Since then two additionally standards for white balanced film has been adopted for use with tungsten lighting: 3200 and 3400.
Colour film images can easily be tainted by a colour cast created by a light source that the film has not been formulated for. Therefore, the right choice of colour balanced film should be considered and loaded before shooting or / and additional coloured filters should be considered and fitted to the end of the lens of the camera to correct for the colour cast that the light source is expected to create.
In digital photography this problem still persists but can be easily corrected by either simply selecting a white balance option from the camera’s menu system of pre-programmed choices or if photographing in RAW by altering the white balance later-on using photo editing software on a computer.
However, it is best practice to always set white balance on your camera before shooting as will save time later on in post editing.
On most DSLRs there is an option to create custom white balance by taking a measurement from a 18% grey-card and on some professional cameras a specific temperature value can be set.
shaun512659 