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C
COLOR TEMPERATURE
A measure of the "warmth" or "coolness" of light sources and colors.
Measured in degrees Kelvin. A higher color temperature light source will
appear whiter (colder). The human brain automatically compensates for
different color temperatures - a film or video camera cannot, and thus what
we see as white may appear to have a blue or green tint when no color
correction is used for video. Most video cameras have a "White Balance"
control to make color temperature adjustments, to ensure white looks white
on camera.
Daylight is approximately 5600°K, Tungsten Halogen is approx. 3200°K and
standard incandescent lamps are 2800°K. Many discharge light sources are in
use in modern theatrical productions using discharge followspots or moving
lights - color correction filters are used to balance the color
temperatures.
COMPLEMENTARY COLORS
Pairs of colors which, when additively mixed, combine to produce white
light. Examples are red + cyan, green + magenta, and yellow + blue.
CONCAVE
Lens shape. Edges are wider than the center of the lens. Useful to remember
that "caves" go inward.
CONDENSER LENS
Loosely applied to any spotlight lens which condenses diverging rays into a
beam, but more correctly to the short focus combination of two or more
lenses in a jacket used for illuminating a slide or effect disc. Also used
in some profile lanterns and followspots to produce a smoother light
(especially for gobo work).
CONDUIT
Metal or plastic pipe used to carry electrical conductors as part of a
permanent electrical installation.
CONTROL ROOM
Room at the rear of the auditorium (in a proscenium theater) where lighting
and sometimes sound is operated from. Known in the US as the BOOTH. The
stage manager calling the cues is very often at the side of the stage
(traditionally stage left) but in some venues he/she may be in the control
room also. The control room is usually soundproofed from the auditorium so
that communications between operators cannot be heard by the audience. A
large viewing window is obviously essential, as is a "show relay" system so
that the performance can be heard by the operators. Obviously if sound is
being mixed, the operator should be able to hear the same as the audience,
so some control rooms have sliding or removable windows, or a completely
separate room for sound mixing. Where possible, the sound desk is moved into
the auditorium so that the operator can hear the same as the audience.
CONVEX
Lens shape. Edges are thinner than the center of the lens.
COVE
US for front of house catwalk lighting positions. Also "Balcony Rail".
CP
Lighting Industry Forum code which identifies the (original) recommended
usage of different lamp types. CP coded lamps are for Film, Television and
Photographic studio use and have a color temperature of 3200°K.
CRACKED OIL
A smoke effect which creates a haze in the air to make light beams visible.
This effect is rarely used now, because it has been found to be
carcinogenic.
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