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H
HEADS ON STAGE
A shouted warning (often just "Heads !") for staff to be aware of activity above them. Also used when an object is being dropped from above.
HEADSET
- General term for theater communication equipment.
- A headphone and microphone combination used in such communications systems with a beltpack.
HEATSHIELD
Made by Rosco, Heat Shield is a special clear gel which when placed between a lamp and a colored gel, dissipates a large amount of heat to give the gel a longer life. There must be an air gap between the Heat Shield and the gel, or it will not be effective.
HID (HIGH INTENSITY DISCHARGE)
High intensity discharge lamp: an electric lamp that produces light directly from an arc discharge under high pressure. Metal halide, high pressure sodium, and mercury vapor are types of HID lamps. A type of lamp such as a mercury or sodium vapor lamp that produces light by causing an inert gas to discharge photons. HID lamps find special uses in entertainment lighting and make good UV sources. HID lamps require special ballasts and are generally not dimmable.
HIGH PRESSURE SODIUM LAMP
An HID lamp in which radiation from sodium vapor under high pressure produces visible light, characterized by a golden-yellow color.
HIGHEST TAKES PRECEDENCE
Abbreviated to HTP, this is the standard by which some lighting desks operate.
If there is more than one control on the desk affecting a particular channel, then the highest level of the controls will take priority and affect the output of the desk and the dimmers. This system is universal on manual lighting desks, but there are problems with the control of moving lights, scrollers etc.
HMI (HALIDE METAL INERT GAS)
A double ended short arc lamp which creates light by causing an electrical current to jump between two electrodes within an inert gas atmosphere. HMI lamps produce many lumens per watt making them many times more efficient
than incandescent sources. HMI lamps typically burn at around 5600 Kelvin.
HMI (Hydragyrum Medium arc-length Iodide)
A mercury-halide discharge lamp with a color temperature of 5600K (daylight).
HOOK CLAMP
- A clamp with a wing bolt for hanging a lantern on a horizontal lighting bar.
- Introduced in the UK in 1959 by Strand, replacing the 2-bolt and 2-nut L Clamp.
HOOK UP
A Hook Up is paperwork generated by the Lighting Designer for a show. It lists connections or layouts between number systems. For example, a Channel Hook Up lists the channel numbers used on the lighting plan alongside the dimmer numbers into which they're connected, and a brief text description of that channels function.
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