The distance between fixture and target, used with the beam or field angle to work out pool size and with the inverse square law to estimate brightness. Long-throw positions, such as a theater's front-of-house balcony rail or a stadium's catwalk, need narrow-angle fixtures, while short-throw positions use wider ones. Catalogs and photometric tools list fixtures by the throw distance they suit.
Throw from the balcony rail is 22 meters, so the 26 degree lekos will be too big, swap them for 14s.
Also heard as
- throw distance
Related terms
Beam angle
The angle across a light's beam at which intensity has fallen to 50 percent of its center value.
Field angle
The angle across a light's beam at which intensity falls to 10 percent of its peak, marking the usable edge of the light.
Inverse square law
The rule that illuminance from a point source falls with the square of distance, so double the distance gives a quarter of the light.
Followspot
A powerful, manually aimed spotlight that an operator keeps on a moving performer throughout a scene.