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B

BIRDIE
A compact low voltage display luminair containing a Par 16 or MR16 lamp. So called because it is similar to, but much smaller than, the Parcan, and is hence "one under Par". (It's a golfing reference). Requires a 12 Volt external transformer, but is ideal for concealing in pieces of set or as downstage uplights.

BLACK HOLE
Accidentally unlit portion of the stage.

BLACKBODY
A temperature radiator of uniform temperature whose radiant exitance in all parts of the spectrum is maximum obtainable from any temperature radiator of the same temperature; Correlated color temperature (CCT) correlates with the apparent color of a blackbody radiator at a given temperature.

BLACKLIGHT
Lighting fixture producing ultra violet light that makes luminescent material glow in the dark.

BLACKOUT (B.O., B/O)

• A lighting design term referring to a light cue which takes the stage quickly into darkness. A blackout is often abbreviated B/O.
• Complete absence of stage lighting. Blue working lights backstage should remain on and are not usually under the control of the board, except during a Dead Blackout (DBO), when there is no onstage light. Exit signs and other emergency lighting must remain on at all times. The act of turning off (or fading out) stage lighting.

BLACKWRAP
Thin black aluminum product which is used to temporarily mask light coming out of a luminair's body, or to control spill. A self-adhesive tape version is also available.

BLEECON
Trade name for a type of low voltage 8 pin connector which is similar to the audio DIN plug. Used most often for carrying signals from analog lighting control desks to dimmers or to demux boxes. Originally manufactured by Belling and Lee, hence BLEEcon (for connector).

BLEED THROUGH
Transformation from a scene downstage of a gauze to another scene upstage, by slowly crossfading lighting from downstage to upstage. If a gauze is lit steeply, or from the sides, it will appear solid. If this light is turned off and light added to the set upstage of it, it will disappear.