Stray light around the edges of a beam, through gaps in shielding or off the back of a luminaire. On stage, spill lands on scenery or masking and is cut with shutters, barn doors or a top hat; on film sets it is controlled with flags; outdoors it becomes light trespass when it crosses a property line. Designers talk about spill when a beam or optic wastes light beyond its target.
There's spill from the box boom hitting the proscenium, cut it with the top shutter before the run tonight.
Also heard as
- spill light
- stray light
Related terms
Light trespass
Unwanted light that crosses a property line or falls where it is not needed, such as into a neighbor's window.
Flag
A black fabric panel on a frame used on film sets to block light from hitting part of a scene or the lens.
Beam angle
The angle across a light's beam at which intensity has fallen to 50 percent of its center value.
Cutoff
The angle above which a luminaire emits little or no light, used to classify glare and light pollution control.