In photography a diffuser is any device that diffuses light. Put simply diffusers make hard light soft. They are usually made up of translucent materials and are placed between the light source and the subject photographed.
|Diffusers used in photography to soften light|
Diffusers affect the light in two ways
It softens the light reducing harshness and there by produces soft shadow edges which appear like a gradient rather than like defined edges. The contrast of the shadow region will also be less. Diffusers alter the size of the light source (this is the reason for softened light). When a diffuser is placed between the light source and the subject; the diffuser becomes the new light source. As a result there are two changes that happens to light, one is the distance from the light source to the subject is reduced. And second is the size of the light source is altered. The diffusers size is the size of the light source now.
A larger light source placed even closer to the subject will be proportionately much bigger than the original configuration and hence much softer lighting. There are also opaque diffusers that work on the reflective principle. Unlike translucent diffusers they are not placed between the light source and the subject; instead the light source is placed between the diffuser and the subject pointed towards the diffuser. The light emitted from the light sources bounces off the diffuser to reach the subject.
How large or how small a diffuser should be is relative to the size of the subject being photographed and also the resultant looks you wish to achieve as a creative artist. Diffusers need not be highly expensive commercially produced ones, thermocol sheets, white bed sheets, shower curtains, butter paper etc. make excellent diffusive materials.
In the next article we will discuss about Photographic Lighting Accessories - Clamp