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Lighting Terms & Definitions

TERMS & DEFINITIONS

Fixture – A device or enclosure hold a bulb or lamp.

Throw – The distance a fixture is designed to concentrate light.

Beam – The size of the throw of the light.

Spot – A fixture and/or bulb designed to give a concentrated light beam sometimes with a very define edge.

Flood or fill – A fixture and/or bulb designed to give a soft and wide beam of light whose edges and defuse (not well defined).

Focus – The ability of a fixture to define the edges of a beam or to change from spot to flood (or fill).

Barn doors – An accessory when installed on the front of a fixture can act like a set of blinders on a horse and prevent light from shining into an area.

Gel – A colored piece of high temperature cellophane which “colors” the light from a fixture.

Gel frame – A metal holder for Gels.

Gobo – A stencil that is inserted into certain types of lights and projects the images that are etched on the Gobo.

Safety – A cable that is required to keep a light from fall in case to becomes detached from it's mounting.

Bar – A pipe either suspended or raised from a stand to hold lights and/or speakers. Tree – A “T” shaped set of bars to hold light fixtures.

Truss – A grid like triangular or square structure that can be suspended or held up with vertical pieces of truss.

Grid – A system of trusses either suspended or held up by vertical trusses that contain lighting and/or sound equipment.

Prerig – A truss that has lighting already installed.

Dimmer(s) – A device that adjusts the voltage in order to adjust the intensity of light(s).

Dimmer packs – A set or array of dimmers controlled by a light control board.

Light Control Board – A central control panel that can be manual or programmable.

Control Cable – Any cable that is used to control either dimmer packs and/or intelligent light(s).

DMX Cable – A style of control cable (also used in audio).

TYPES OF LIGHTS

Par or Par Can – A fill or spot type of light. The “can” holds the bulb. The style of light depends upon the lamp installed, either flood or spot.

Fresnel (Firnel) – A fixture with a lens. Some Fresnel are adjustable from flood to spot. The light even when set to spot and a defuse (soft) edge. Can use both gels and barn doors with this light.

Ellipsoidal (Lico) – A spot light with both a lens and well defined beam edge. This type of light comes with in many variations. Some have a fixed beam, others have interchangeable lens in order to adjust the size of the beam. These lights can use barn doors, gel and Gobos.

Follow Spot – A manned light with features similar to ellipsoidal's but controllable by the operator. This type of light normally has multiple gel, a shutter to close the light, an iris to shrink the size of the beam. These lights normally have a focus to sharpen or defuse the edges of the light beam.

Intelligent Light – A general category for lights that have multiple functions and are controlled (or programmed) remotely.

SAFETY

Exit signs – A sign either directing or indicating an exit from a structure or tent. Sign are also required to have a battery backup incase of power outage.

Emergency Lighting – A set of lights which energize when their is a power outage. These lights work on a backup battery.

DISCUSSION ON ADEQUATE LIGHTING

Ellipsoidal – Gobo chart

DISTANCE	VERY WIDE 50		WIDE 36		MEDIUM 26		NARROW 19
IN FEET	BEAM	GOBO	BEAM	GOBO	BEAM	GOBO	BEAM	GOBO
10	9.6	6.0	6.3	4.5	4.5	3.3	3.2	2.7
15	14.4	9.0	9.4	6.8	6.7	5.0	4.8	4.1
20	19.2	12.0	12.5	9.0	8.9	6.6	6.3	5.4
25	24.0	15.0	15.7	11.3	11.2	8.3	7.9	6.8
30	28.8	18.0	18.8	13.5	13.4	9.9	9.5	8.1
35	33.6	21.0	21.9	15.8	15.6	11.6	11.1	9.5
40	38.4	24.0	25.0	18.0	17.8	13.2	12.6	10.8
45	43.2	27.0	28.2	20.3	20.1	14.9	14.2	12.2
50	48.0	30.0	31.3	22.5	22.3	16.5	15.8	13.5
55	52.8	33.0	34.4	24.8	24.5	18.2	17.4	14.9
60	57.6	36.0	37.5	27.0	26.7	19.8	18.9	16.2
65	62.4	39.0	40.7	29.3	29.0	21.5	20.5	17.6
70	67.2	42.0	43.8	31.5	31.2	23.1	22.1	18.9
75	72.0	45.0	46.9	33.8	33.4	24.8	23.7	20.3