Leprecon LP-3000 Series - Manual (Page 86)

82 Chapter Seven Moving Light Controller—Overview
LP-3000 Users Manual
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Intensity—The brightness of the beam, usually controlled by a mechanical
dimmer in a moving light.
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Focus—The position of the beam and sharpness or definition of the beam
edge.
All effects produced by modern moving lights are based on these four properties.
The following list details the elements that are present in most moving lights.
Color (Color Property)
Color effects in a moving light are generally produced by placing a color media in
the path of the beam. Dichroic filters are the media of choice. Usually a disc with
several filters is placed so that rotating the disc will move one of the filters into
position. Some fixtures have the ability to spin the color wheel continuously for an
entertaining effect.
Color Mixing (Color Property)
Some advanced instruments use the combination of three-color media to produce a
wide range of colors. Usually referred to as CYM or color mixing, three channels are
used to set the relative saturation of the component colors. This also allows fading
from one color to another without the abrupt change that is characteristic of a
rotating color wheel.
Gobo (Beam Property)
A gobo is a cut out pattern that is inserted into the beam so as to project a pattern
on the stage. Scholars have traced the term “gobo” to the Italian term for an idiot,
translated as “dim bulb”. We are unsure of the significance of this fact. Suffice to
say that the gobo has been around about as long as instruments with lenses.
As with color wheels, gobo wheels are positioned in the light beam and can be
rotated to the proper position on cue. Some gobo sizes are standardized which
allows custom gobo patterns to be fabricated and inserted into the gobo wheel for
specific effects.
Shutter (Beam Property)
To produce a fast blackout, a mechanical shutter is used that blocks all light output
very quickly. Opening and closing the shutter rapidly is used as a strobe effect.
Iris (Beam Property)
The iris of a Moving Light is identical to any other iris—a clever multi-leaf element
that produces a variable sized round aperture. As the iris size changes, the intensity
of the remaining beam remains constant.
Rotating and Indexed Gobos (Beam Property)
Another special effect is the ability to rotate a gobo pattern. This is not to be
confused with spinning the entire wheel. Still another stepper motor is used to
rotate the individual gobo in its position on the gobo wheel. Usually another control
channel is used to set the rate and direction of the rotation. An associated effect
allows the gobo to be precisely oriented, or indexed. This is important when the
pattern is projected, such as a corporate logo.