I like to start all theatre lighting workshops by going outside and looking at the lighting that is occurring, which is being influenced by the weather, location, time of day.
The basic properties of light that I consider that influence stage lighting are: DISCM
Direction
Intensity
Shape
Colour
Movement
The Direction that light comes from is important in determining how we reveal or hide people and objects. It also helps to determine the time of day and location an event is occurring. If we go outside, the direction that natural and artificial light comes from needs to be observed, so we can recreate it on stage.
The Intensity of natural light depends on the time of day, the weather conditions and the location. We can control the Intensity of conventional theatre lighting by varying the current through the lamp with a dimmer, or by using neutral density filters. We can control the intensity of discharge lamps such as those used in moving lights by using a mechanical dimmer or shutter.
The Shape of the light is determined by what influences the parallel beams of light arriving from the sun for natural light or by the emitting source for artificial light.
If something is obstructing the beam of light such as a tree, we may see the shape of leaves on the ground underneath the tree.
The Colour of light sets the scene in our mind and impacts on our brains emotions.
There are two methods of changing the Wavelength or Colour of light, Subtractive and Additive.
The Subtractive method uses a lighting filter or gel to only allow a narrow spectrum of light pass through the filter, the remaining parts of the light spectrum is dissipated as heat in the filter. The subtractive method was developed for conventional lighting. With the development of moving lights the subtractive method used Cyan, Magenta and Yellow dichroic filters or flags.
The Additive method uses the output of different coloured emtters to make up a desired colour. Initially there was Red, Green and Blue colours used, then White was added to get soft pastels for theatre and Amber was added to get strong saturated colours for musicals and bands.
Movement of natural light is perceived, such as a person walking underneath a tree where we see the dappled sunlight producing a sense of movement, or when sunlight is relfected off rippling water.
page updated 14 October 2022