The Colour of Light

Different light sources emit at different wavelengths, which we see as colour. The diagram below shows the colour temperature of a wide range of natural and artificial sources of illumination. High colour temperatures are at the blue end of the scale, and low colour temperatures shift to the red end. The human brain, however, in conjunction with the eye has the remarkable ability to 'filter' these variances so that all sources of light are seen pretty much as 'white light'. Cameras cannot do this - they require different filtration for each type of light whether it be physical - a screw on filter, or electronic - the White Balance setting on digicams.

Colour Temperature/Filter Chart

Condition

Temperature (Kelvins)

Colour Correction Filter

Domestic lightbulb

2900

80A + 82B

Tungsten Halogen/Photolamps

3200

80A

Photofloods

3400

80B

Early morning/late afternoon

5400

82C

Noon daylight

5500

None

Overcast sky

6500

81B

Heavy overcast

7500

81C

Shade under blue sky

8500

85C

Download a copy of an excellent program to digitally replicate Kodak Wratten Filters - recommended!

Knowing what the colur temperature of a scene's lighting is can become extremely important when colour accuracy is required.With the E-10, this can be achieved in five ways: using the fixed WB settings, taking a manual WB reading (from a white surface), relying on Auto WB (a bit 'hit and miss'), using a front-of-lens filter, or combinations of all five.Why bother, you ask? Well, the E-10s' WB settings are incremented at 3000k, 3700k, 4000k, 4500k, 5500k, 6500k and 7500k; and as you can see from the colour temperature chart above, they don't quite match some of the key temperatures - a problem if total accuracy is called for. Manual WB is very good, but can still be fooled - and do you always have a totally flat-white object to hand? Experimentation is the key here, and without the burden of film costs - why not? Photoshop or similar image manipulation packages can do much to offset these colour cast problems, but I always prefer to have the original image as accurate as possible - any digital manipulation can adversely affect the integrity of the image projected by the lens. This is one of the key reasons why the E-10 has a RAW image capture mode, is it not?

Article Sections:

Light

Harmony in the hand

Hold pointer over buttons for destination - click to go there!