Leprecon LP-X24 Manual v3.2 - Manual (Page 88)

84 Chapter Four Moving Light Programming
LP-X24 and LP-X48 Users Manual
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.
Effects: Prisms and Frost (Beam Property)
The number of elements that can be introduced into the optic path is limited only by the
imagination of instrument designers and the budgets of the users. Besides the standards
of gobo and color, several popular instruments incorporate another general-purpose
wheel for effects. These can include prisms to split the beam, color correction filters and
diffusion media or “frost”. The exact features that are loaded in an effects wheel can vary
widely.
Zoom and Focus (Beam Property)
Because Moving Lights are used for their static properties as well as their ability to
move, manufacturers have added motor controls to the optics. The results are the ability
to control the “sharpness” or definition of the beam edge (focus) and the size of the
projected beam (zoom). Controlling the beam size with the iris maintains the intensity as
the area of coverage changes. Zooming the fixture concentrates the light into a larger or
smaller area with a corresponding change in illumination.
Dimmer (Intensity Property)
The high-performance Moving Lights of today usually utilize discharge lamps as a light
source. These arc lamps are compact, efficient and have a high color temperature. On
the down side, they require a large and heavy ballast and cannot be dimmed electrically.
As a result, the dimming system usually consists of a mechanical element such as a disk
with progressively narrower slots.
Mirror (Focus Property)
The positioning of the mirror is responsible for the “focus” or position of the beam.
Generally, stepper motors are used to set the mirror position, with an XY axis for pan
and tilt. Some instruments use a single 8-bit value for mirror position; other instruments
use a 16-bit value. This information is significant only for ensuring that the LP-X set-up
for an instrument is correct.