Measured edge to edge across the beam at the points where intensity has fallen to 10 percent of the peak. It describes how far the visible light extends beyond the bright core described by beam angle, and is the figure stage lighting catalogs use to size ellipsoidal fixtures, such as 19, 26, 36 and 50 degree lens tubes. The gap between beam and field angle shows how hard or soft the beam edge is.
Field angle on the 36 degree lens covers the whole downstage area from the first electric, the beam angle alone wouldn't.
Also heard as
- field spread
Related terms
Beam angle
The angle across a light's beam at which intensity has fallen to 50 percent of its center value.
Leko
Theater slang for an ellipsoidal reflector spotlight, the hard-edged fixture with shutters and a gobo slot.
Throw
The distance from a lighting fixture to the surface or subject it lights, which sets beam size and intensity.
Spill
Light that falls outside the area it is aimed at, onto walls, ceilings, audiences or neighbors.