natural light: project 41
June 26, 2010
your eye’s sensitivity to colour
The images below, taken from projects 32 and 33, are arranged in such a way to illustrate their order within the spectrum. Also, the curve formed by the images illustrates the eye’s sensitivity to colour – the colours that are darker are lower within the graph and those which are lighter are higher.
Radio waves, x-rays, radar and light are all electromagnetic radiation that are invisible to the eye with the exception of light which (because of the sensitivity of the human eye) is visible. Radiation is defined by wavelength and visible wavelengths are the colours of the spectrum.
Mixing all these colours together ( which our eyes do ) results in white light. Sunlight is the standard not only for brightness, but for colour. In the middle of the day sunlight seems colourless and we call it white light. Light becomes colour when some parts of the spectrum are missing. An example of this is when the sun is setting. On a clear day and dependant on the weather conditions as the sun starts to get lower in the sky it becomes yellow, lower still and it becomes orange. The best of sunsets are red when touching the horizon. The reason for this is that all the particles in the atmosphere scatter some of the light – and there is more atmosphere between you and the sun at sunset. The shorter wavelengths get scattered more easily leaving the longer ones visible. It is the blue that gets scattered, so what remains looks orange or reddish. The blue wavelengths that have been scattered makes the sky away from the sun look blue.
The possible colours of daylight can be red, white and blue. Photographic manufacturers make filters to alter the colour of light in order to achieve the desired colour of daylight.
The colour of the sun from white to red can be given a figure ( in degrees of temperature ) which is useful for calculating what filters to use. This is called the Kelvin Scale – starting at the lowest possible temperature called absolute zero.
What I have learnt
The awarness of the variety of outdoor light.
