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H
HALOGEN CYCLE
Chemical process occurring in Tungsten Halogen lamps which makes them
possible. During the lamps life, Tungsten evaporates from the filament, and
would normally deposit itself on the glass wall of a Tungsten lamp, causing
it to blacken, and causing the output of the lamp to reduce until it finally
blew. In a Tungsten Halogen lamp, the Tungsten combines with the Halogen gas
elements present in the lamp envelope and is re-deposited back onto the
filament. This process needs a very high temperature to operate, so Tungsten
Halogen lamps are able to be a lot smaller, and run a lot hotter, than their
Tungsten equivalents.
HANG
The "hang" is the American equivalent of the lighting rigging session in the
UK - the time when the lighting equipment is rigged.
HARMONY
Range of 1000W lanterns produced by Rank Strand (now Strand Lighting) in the
UK.
HEADS
The top lantern on a lighting boom.
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
1) General term for theater communication equipment.
2) 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.
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 (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.
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