Ambient light is the available light in a scene, or “natural” light. Photos taken in natural light use are lit just by the the existing light sources – for example, the low sunlight coming through the window. All three pictures below were taken by William Eggleston with ambient lighting.
You use Artificial light when you want more light, different light, or more creative control over the lighting in the scene. Artificial lighting is adding light to a scene where you can control the strength, direction and quality of the light. The photos below are taken with staged lighting and therefore look like a film set.
Diffused light is soft light, a good example of this is the natural lighting on an overcast day – the sun has been blocked by clouds and only a minimal amount is making its way through and onto the subject. To achieve soft light you must have a large light source, this makes the shadows softer and harder to define, and that is the definition of diffused/soft light.
Hard light is the opposite of soft/diffused light; a small, bright, pointed light source, that hit the subject and cast sharp, defined shadows. Lots of artistic photos taken with hard light are shot in black and white.
Coloured light is used in cinematography to tell a story and create a mood. It’s also quite commonly used in fashion photography. Coloured lights/gels are shone on and around the subject to give it a glow the same colour of the light.
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