White Balancing and watch photography
Posted by Paul Delury on January 07, 2002 at 21:07:21:
TZ Classics Forum Number: 1886
Posted from Host: (18.104.22.168)
Light can have different colour temperatures, although the human eye/mind combination effectively compensates for the colour differences and we don’t “see” them (although when you move quickly from inside to outside on a sunny day you may experience the colour difference for a short time before the mind takes over). For example, sunlight has a blue colour cast, incandescent globes are reddish/orange, and fluorescent lighting is yellow/green. Colour temperature is measured in degrees Kelvin, and light from different parts of the visible spectrum has varying energy.
Digital/Video cameras and film do not have the same ability as the human mind to compensate for varying light sources. They record whatever colour is actually there, if steps are not taken to correct he colour cast. The White Balance feature on a digital or video camera is a means of compensating, or biasing, for the different nature of light. When you White Balance for outdoor sunlight, the camera’s programme will sample the light and filter it to remove the blue colour cast, so that whites in the picture will look white, rather than a sickly bluish-white. The same occurs for indoor lighting, with filtering being applied to the red/orange, or yellow/green part of the signal, depending on the lighting used. Digital cameras generally allow you to balance for at least the 3 main forms of lighting – sunlight, incandescent, and fluorescent.
Here is a visual representation of how a picture may look if not white balanced correctly.
Incandescent light gives a red/orange colour cast
Fluorescent light gives a green/yellow colour cast
White balanced to eliminate colour cast