Lighting
Why is lighting important?
Lighting terminology – what is and isn’t relevant?
Lighting terminology – what is and isn’t relevant?
The wavelength, measured in nanometers (nm), of a particular light defines how it interacts with the surfaces it hits. For example light of 660nm is perceived as red when it hits a human eye, and is absorbed when it hits a blue coloured surface. Some light (including white) is made up of a number of different wavelengths mixed together. The visible spectrum for humans is roughly 400-700nm, but there is varying sensitivity within that range. For example a green light will look brighter than a blue light even if they are of the same radiant flux (W). It is important to note that other species will have different visible spectra and sensitivities.
A spectrum graph is a visual representation of the mix of wavelengths in a light source (both in the visible spectrum and beyond). This is very important to consider because of the variation between the way human's experience light when compared to other animals. We might be able to see well under a light that is very dim to a particular animal species, or vice versa. For example pigs can’t see red light at all, so a white light that emits a large amount of red (e.g. an incandescent bulb) will seem dim to a pig, but bright to a human. Furthermore certain wavelengths may be important due to their biological effects on structures such as the pineal gland (affecting circadian rhythm), so this should be considered when specifying. Spectrum is also important when dealing with plants because although plants do not experience attenuated light to the same extent as fish, different plant species have different spectral requirements and some wavelengths will be more important than others at different stages of development.