STAGE CREW
Lighting Training
Manual
Level 2:
Understanding & Using
Light
USSU Stage Crew
Level 2A Training Manual
Revision Record:
This document is only to be reissued in its entirety.
Issue
0.1
0.2
Revision Comment
Initial Draft
Updated for first use
2
Revised By
R. White
R. White &
P. Budd
Issue Date
Dec 2008
February
2010
USSU Stage Crew
Level 2A Training Manual
CONTENTS
1. INTRODUCTION ..........................................................................................................................4
2. OBJECTIVES OF STAGE LIGHTING .........................................................................................5
2.1 VISIBILITY ................................................................................................................... 5
2.2 NATURALISM (and MOTIVATION)............................................................................. 5
2.3 COMPOSITION ........................................................................................................... 5
2.4 MOOD .......................................................................................................................... 5
3. USING LIGHT AND IT’S PROPERTIES ......................................................................................6
3.1 INTENSITY (and BRIGHTNESS) .................................................................................... 6
3.2 FORM AND DISTRIBUTION ........................................................................................... 6
3.3 DIRECTION AND MOVEMENT ...................................................................................... 7
3.3.1 DIRECTION .............................................................................................................. 7
3.3.2 REFLECTIONS....................................................................................................... 11
3.3.3 MOVEMENT ........................................................................................................... 12
3.3.4 SURFACE TRANSPARENCY (GAUZES) ................................................................. 12
3.4 COLOUR ....................................................................................................................... 14
3.4.1 COLOUR PROPERTIES ........................................................................................ 14
3.4.2 COLOUR MIXING................................................................................................... 15
4. GETTING TO KNOW LIGHTS .................................................................................................. 18
4.1 TYPES OF LIGHT SOURCE ........................................................................................ 18
4.2 COMPONENTS OF A LIGHTING FIXTURE................................................................. 20
4.2.1 LAMPS .................................................................................................................... 20
4.2.2 REFLECTORS........................................................................................................ 14
4.2.3 LENSES .................................................................................................................. 15
4.2.4 SHUTTERS AND IRISES ....................................................................................... 17
4.2.5 GOBOS ................................................................................................................... 18
4.2.6 GELL FRAMES & HOLDERS ................................................................................. 20
4.2.7 BARN DOORS........................................................................................................ 21
4.3 PHOTOMETRICS ......................................................................................................... 22
5. CARING FOR YOUR LIGHTS .................................................................................................. 23
5.1
CHANGING LAMPS ............................................................................................... 23
5.2
CARING FOR OPTICS .......................................................................................... 23
5.3
CLEANING LAMP BODIES ................................................................................... 23
5.4
ELECTRICAL CHECKS ......................................................................................... 24
6 BUILDING YOUR LIGHTING RIG ............................................................................................. 25
6.1 RIGGING ................................................................................................................... 25
6.2 FOCUSING ................................................................................................................ 26
7 DIMMERS ................................................................................................................................... 28
7.1 CONTROL INPUT ..................................................................................................... 28
7.2 CONTROLLED OUTPUT .......................................................................................... 28
7.3 OUTPUT PATCHING ................................................................................................ 28
8 CONTROL DESKS..................................................................................................................... 30
8.1 WHAT THE KNOBS DO ............................................................................................ 30
8.2 LIGHTING DESK OUTPUT ....................................................................................... 31
8.3 INTELLIGENT LIGHTING DESKS ............................................................................ 33
9. INTELEGENT FIXTURES ......................................................................................................... 34
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1. INTRODUCTION
Stage lighting is no longer a matter of simple illumination as it was less than 100
years ago. Today, lighting designers are expected to be a master of art, science,
psychology, and communications.
The stage designer quickly learns that things are not always what they appear to be.
A director, who asks for 'more light' on an actor, probably doesn't mean that at all.
Instead he really just wants 'to see the actor better'. So the lighting designer also has
to be a good listener, a careful interpreter and a skilled crafts person.
Ultimately the lighting designer must be an artist! They must understand style,
composition, balance, aesthetics and human emotions. He must also understand the
science of light, optics, vision, the psychology of perception and lighting technology.
When it's good lighting design you alone will know.
When it's bad lighting design everyone will tell you!
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2. OBJECTIVES OF STAGE LIGHTING
"Stage lighting may be defined as the use of light to create a sense of VISIBILITY,
NATURALISM, COMPOSITION and MOOD, (or ATMOSPHERE)" ('A Syllabus of
Stage Lighting' by Stanley McCandless.)
2.1 VISIBILITY
VISIBILITY is often considered to be the most basic and fundamental function of
stage lighting. What we don't see, we seldom clearly understand. Visibility is
dependent on far more than just the intensity of light. Other factors such as; contrast,
size, colour and movement all can influence visibility. Distance, age and the condition
of the eye also play important roles in visibility. "Good visibility is essentially selective.
Its purpose is to reveal things selectively in terms of degrees of acuity". (S.
McCandless, 1933).
2.2 NATURALISM (and MOTIVATION)
NATURALISM provides a sense of TIME and PLACE. Stage settings may be highly
realistic or completely abstract, absurd, or stylized. If time of day is important or the
place is realistic, then MOTIVATION is often provided by sunlight, moonlight, firelight,
lamplight, or other naturalistic stage sources. Style concepts include: naturalistic,
realistic, surrealistic, futuristic, minimalistic, impressionistic.
2.3 COMPOSITION
COMPOSITION refers to the overall pictorial aspect of the stage, as influenced by
the lighting. Composition also deals with the FORM of an object. A stage scene may
be broadly flooded with soft, even lighting, revealing every object equally, or it may
be illuminated by highly localized lighting on the actors only or anything in between.
So, composition in lighting must reveal actors, objects and scenery in proportion to
their importance, by building a visual picture.
2.4 MOOD
MOOD considers the basic psychological reactions of the audience. If other lighting
elements have been properly applied, the result is a specific MOOD, created by the
lighting design. Lighting can cause an audience to feel a wide range of different
emotions. Feelings of 'happy, sad, content, horrified, excited, (and often 'bored'), all
depend on a wide number of psychological and physiological factors. This is also true
in respect to how the audience interprets naturalistic or atmospheric moods, such as
sunny, cloudy, rainy, lightning, etc. The stage lighting designer rapidly learns that:
"Things are not what they are; things are what they appear to be.”
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3. USING LIGHT AND IT’S PROPERTIES
3.1 INTENSITY (and BRIGHTNESS)
INTENSITY typical refers to the 'strength' of a light source. Intensity of a source
exists independent of its distance.
ILLUMINATION refers to amount of light falling on a surface. The old term for
illuminance was 'illumination'.
BRIGHTNESS refers to the visual sensation caused by a light source when it
interacts with an object and then the eye. Brightness depends on the intensity of the
source, on the distance to the object and on the reflective properties of the object.
Example: In theatre when we change the dimmer setting of a
lighting fixture, we are changing the output INTENSITY of the
source. This results in a change of ILLUMINANCE (light falling on
the stage) that is perceived by the eye as a change in
BRIGHTNESS.
VISIBILITY depends on many factors, not just the intensity of a source or the
brightness of an object. Colour, contrast, distance, movement and the conditions of
the eye and visual system all play an important role towards visibility. Objects of
higher brightness generally draw attention on stage. Light attracts! Conversely,
darkness conceals but may also put the audience to sleep. One of the prime jobs of
the lighting designer is to actually keep the audience awake. This is not as funny as
you may think when you consider what we do to an average audience member.
Usually late, after dinner and a few drinks we seat the audience in comfortable chairs
and then turn off all the lights! The lighting designer must use the power of light to
keep the audience awake and direct their attention to the stage by providing proper
visibility, interest and selective focus.
3.2 FORM AND DISTRIBUTION
Light provides objects with a sense of FORM. The eye is able to recognize objects in
terms of shape, size and position. Our binocular vision assists with this process by
providing DEPTH. "By means of controlling the distribution of light and creating
patterns and compositions of light and shade, it is possible to produce sensations on
the retina that will be interpreted as forms in space." (A Syllabus of Stage Lighting, S.
McCandless 1964).
Form as applied to light is rather complex. It is everything that intensity, colour,
movement and direction are not. Yet form is caused and influenced by these other
qualities of light. Form has to do with the DISTRIBUTION of light or how light strikes
a surface and reveals an object. We typically discuss form in terms of clarity and
recognition of shapes. Form and distribution can be discussed on two levels. First,
we can discuss form as applied to the stage setting in respect to how objects appear.
A stage might be evenly, softly and flatly illuminated from a low front angle.
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Alternately, the same stage might be unevenly dappled with tight circular pools from
a high overhead angle.
As in nature, stage light sources may produce either soft diffused shadowless light or
hard shadow producing light, or anything in between. The edge of a lighting beam
may also range from a soft almost invisible edge to a hard, sharply defined edge. A
beam of light may also have a broken, uneven distribution, as in the case of a gobo
or template pattern projection.
3.3 DIRECTION AND MOVEMENT
3.3.1 DIRECTION
The direction of light is one of the most important attributes in stage lighting design.
All light has direction. A bare candle radiates light in all directions. A spotlight
radiates light in a very specific direction. In nature most light comes from the sky,
from above.

In theatre lighting this is also generally true as most lighting positions are
above the stage or audience. Low front lighting is often considered to be 'flat'.

Very high lighting angles may cause shadows on the actor's faces.

Lighting from more than one direction can add dimension to an actor.

Lighting from the 'balcony rail' can fill in shadows on the actor's face however
this position can also cause shadows on upstage backdrops or scenery.

Very low lighting angles have always been associated with rather unnatural
lighting and are usually used for effect lighting only.

Footlights, once common in many theatres are seldom used today. Clearly
the lighting designer must chose the direction of light very carefully.

In theatre, like in nature the 'floor' reflects some light from below, usually
filling in shadows.
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Lighting from the front:
A vertical beam is the most selective light possible. The lit area of stage, and the
shadow cast upon it, need be no wider than the widest part of the actor. However,
the actor's eyes will be black pools and a highlighted nose will shade the mouth. If
the light comes from a little forward of the actor, it will start to reach the eyes and
mouth.
However, the lit area, and shadow cast, starts to extend. As the lighting comes
increasingly from the front, the actor's eyes and teeth receive more light. But the area
lit extends further and further upstage, reducing the selectivity and increasing the
likelihood of the actor's shadow hitting the scenery. As the light becomes more and
more frontal, the actor's features become flattened (and so also does three
dimensional scenery). The lit area and the actor's shadows increase until, when the
light is horizontal, there is a lit corridor for the entire depth of the stage, and the actor
shadows become actor length, rising and falling as she moves towards and away
from the light source. When this is the only lighting angle, the effect on the face is not
at all natural. But a little from below, usually just reflected light can help to soften the
harshness of light from above.
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Lighting from the back and side:
A light source behind the actor does not illuminate the face, but it helps to give depth
to the stage by separating the action from the scenery through creating a haze and
highlighting head and shoulders. The shadow of the actor is cast forward, helping the
selection of areas. Since the light does not fall on the face, strong colours can be
used. If the light comes from a little to one side of the actor it will start to reach the
eyes and mouth on that side. The area lit, and the shadows cast, will extend along
the stage floor on the other side.
Add a second light source from the other side, and both sides of the face will receive
light. However, there is now a second shadow and the selected area of stage floor
extends to both sides of the actor. As the side lighting comes from an increasingly
lower angle, the shadows will lengthen to both sides of the actor and a larger corridor
will be selected across the stage.
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As the face is lit from a lower angle, more light will fall onto the eyes and teeth,
although there will still be a tendency towards a central dark line where the beams
meet down the centre of the face. As the angle lowers, sidelight has an increasingly
modelling effect on the actor's face and body. This is particularly important in dance.
When the light becomes horizontal there will be a lighting corridor across the whole
stage. By focusing just clear of the floor, it is possible to lose shadows into the wings,
and the light will only be apparent when an actor stands in it.
Finding the compromise:
We normally seek to light an actor for maximum visibility and maximum modelling,
with minimum shadow. The basic compromise that has long been the standard
approach is a pair of beams crossing on to the actor (one for each side of the face)
from positions that are both forward and to the side of the actor. The suggested angle
is often around 45 degrees in both directions - i.e. midway between vertical and
horizontal and midway between front and side. However to restrict the shadows cast
and to give a better 'join', the lights are often positioned closer to the vertical and to
the centre. A backlight added to the basic crossed pair brings depth to the scene and
generally enhances the 'look' of the actor. The backlight can be used for strong
atmospheric colour if required, while the crossed pair maintains a more natural tint on
the actor's skin tones.
The problem with 'crossed pair' lighting is the extent of the spread of light on floor
and scenery beyond the area where the actor's head is lit. Although a single beam
can be flat it can also be quite tight. Adding a backlight can enhance this flatness
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quite considerably - and the selectivity is still a tightly controlled upstage/downstage
corridor without side spillage. For modelling, sidelights can be added and, although
they will spread, the lit area, they can be at quite steep angles since they do not need
to make a major contribution to visibility.
3.3.2 REFLECTIONS
There are four types of reflection:

Specula Reflection changes the direction of a beam of light without otherwise
appreciably altering the nature of beam. A mirror is a specula reflector.

Diffuse Reflection occurs when the beam of light is completely dispersed. The
light bounces off the reflector in all directions. Example: flat paint.

Spread Reflection is similar to diffuse reflection, except that a greater
percentage of the light is reflected along the angle of reflection than along any
other line. Example: crumpled up aluminium foil.
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Mixed Reflection is a mixture of diffuse and specula reflections. Examples: a
doorknob/ shiny wood floor /gold watch
3.3.3 MOVEMENT
Movement in light is generally taken to mean any change in INTENSITY, COLOR,
FORM or DIRECTION. Dynamic changes in all of these qualities take place in nature
on a regular basis.
Movement may also include the physical movement of a source, such as; a search
light, police beacon, colour wheel, special optical effect, moving projections, mirror
ball, etc. Movement may be rapid or very subtle, slow and unperceivable. Such may
be the case of a designer that provides a slow shift in sunlight from one side of the
stage to the other throughout the duration of a play. The audience may not notice the
shift, however they often may 'feel' the result of the change emotionally. A sunrise or
sunset might also change so slowly that the movement in light is unperceivable and
the audience may only feel the result and not actually see it.
3.3.4 SURFACE TRANSPARENCY (GAUZES)
It should be noted that materials behave differently to different light sources. On of
the best examples of this it the use of a material called Gauze. Gauze is a woven
mesh like material used on stage for effects like reveals.
When the front face is lit at an acute angle and no back light, the material reflects the
light and appears opaque. However when an object is placed behind the gauze is lit
and the front light on the gauze removed, the material then appears translucent to
anyone looking from the front.
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Many other materials will give interesting effects when they are lit in different ways.
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3.4 COLOUR
3.4.1 COLOUR PROPERTIES
All light is coloured. White light is simply a mixture of all visible wavelengths
(colours). The human eye is most sensitive to light in the yellow-green portion of the
visual spectrum (about 550 nanometres), than it is to red or blue at the ends of the
spectrum. Colour is usually discussed in terms of HUE, VALUE and CHROMA.
HUE: the classification of a colour that the eye sees as red, green amber, etc.
VALUE: indicates lightness or darkness of a colour.
CHROMA: indicates the purity or saturation of the colour.
The PRIMARY colours of light are RED, GREEN and BLUE. These three colours can
mix together to produce any other colour, including white. (The primary colours of
pigments are RED, YELLOW and BLUE.)
The SECONDARY colours of light are formed when any 2 primary colours are
combined. The 3 secondary colours are MAGENTA (red & blue), YELLOW (red &
green) and CYAN (blue and green).
THE COMPLEMENTARY colours are any combination of a primary and a secondary
colour that mixed together make white light. Examples of complementary colours are.
MAGENTA & GREEN, YELLOW & BLUE, and CYAN & RED).
When white light is passed through a colour filter only the wavelengths corresponding
to the colour are transmitted. All other wavelengths are absorbed. This is referred to
as SUBTRACTIVE filtering. When 2 or more coloured beams of light combine to
illuminate a surface, they mix together through ADDITIVE mixing.
Stage lighting fixtures produce coloured light using high temperature plastic filters.
There are hundreds of different colours available from several manufacturers. These
filters TRANSMIT their own colour and ABSORB all others. Sometimes glass filters
are also used. Conventional glass filters generally come in a limited range of colours
however they are useful for high temperature applications or where prolonged life of
the filter is required.
Dichroic glass filters are also sometimes used for entertainment lighting applications
where 'vibrant' colours are needed that will not fade over time. Dichroic filters are
made with thin film technology, tuned to specific wavelengths. These filters transmit a
specific colour and REFLECT all others. (Unlike conventional filters that absorb not
reflect unwanted wavelengths.)
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3.4.2 COLOUR MIXING
There are two ways to mix colours in lighting:

Additive mixing happens when two or more differently coloured lights are
aimed at the same surface.

Subtractive mixing happens when a single light source shines through
differently coloured filters. Each filter allows certain colours to pass while
blocking or absorbing other colours.
In additive mixing, primary colours are those three colours which, when aimed at the
same place at the same intensity, theoretically form white light ("theoretically",
because in practice, this is limited by the imperfections of colour filters and light
sources). These colours are red, green, and blue.
The secondary colours in additive mixing are those colours which can be created by
evenly mixing two primaries. These colours are:



Cyan (blue and green)
Magenta (blue and red)
Amber (red and green.)
Additive Mixing:
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Subtractive Mixing:
In subtractive mixing, the primary colours are those which can be created by evenly
mixing two secondary colours, as shown in the drawing above. In the example on the
right, a white light is altered by inserting a cyan filter, which absorbs the red part of
the spectrum and passes (or "transmits") blue and green light. The resulting cyan
light is then passed through a yellow filter. This filter absorbs blue light, but transmits
any red or green that may be present. Since there is no red (because we've already
blocked it with the cyan filter) all that is transmitted is green.
Subtractive mixing is often found in automated fixtures. The act of inserting a colour
filter in front of a light is a very simple form of subtractive mixing.
Complementary colours are those colours directly across from each other on the
colour wheel:
For example: yellow and blue are complementary to each other, as are green and
magenta.
As you can see, the complementary of any primary colour is the secondary colour
formed by mixing the two remaining primaries.
Complementary colours, when combined additively on a neutral surface, form (in
theory) white light.
Complementary colours, when used adjacently, reinforce each other; each makes
the other appear to be more vibrant.
Choosing Colours
Typically it is obvious when colour combinations do not work well, however there are
some basic rules of thumb that can be followed when choosing colours:
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 Green Especially as front lighting makes people look sick.
 Green and green-blues do not work well with dark skin due to the amount of
absorbed light.
 Too much white light will make people look washed out.
 Red colours interfere with cameras. This is important to consider for photos,
recordings and live video.
 Different colours will change the brightness of a fixture. Eg. more purple than
red may be needed in a rig to cope with the difference in brightness.
 Consider how the colour is going to be used in the show two colours next to
one another may give a strong contrast which may not be desirable if a
subtle change is required.
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4. GETTING TO KNOW LIGHTS
This section gives a basic overview of types of light source, their components and
how to use them.
4.1 TYPES OF LIGHT SOURCE
There are a number of different common categories of lights the intention of this
section is to provide an introduction to them.
Profile
A Profile is a type of light designed to focus. They can be used with gobos to project
and image. They are very usefull for picking out the area of a stage.
Fresnel
A Fresnel is a type of light designed to wash an area. They provide limited focusing
and are commonly used with barn doors to avoid spill.
Pebel Convex
A pebel convex light provides a soft edged beam with a slightly narrower focus than a
Fresnel.
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Flood
Flood are very simple they use a reflector to reflect the light forwards. They provide
no focus. They come with symmetrical or asymmetrical reflectors.
Asymmetrical Reflector
Symmetrical Reflector
PAR Can
PAR Cans are very basic very cheap lights, as a consequence of this they are widely
used. The lamp reflector and lens come as one unit as a consequence the beam
angle is selected by the beam angle of the lamp.
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4.2 COMPONENTS OF A LIGHTING FIXTURE
4.2.1 LAMPS
There are quite literally hundreds of different types of lamps used within the
entertainment industry. These vary is size, shape, style, base/connections, voltage,
wattage, chemistry, etc. Most lamps used in the industry were designed for other
purposes and where then stolen by the industry.
LAMP – GIVES OUT LIGHT WHEN
SUPPLIED WITH ELECTRICITY
BULB - GIVES OUT DAFFODILS
WHEN WATERED AND DOESN’T
FIT IN A LAMP HOLDER VERY WELL
Most lamps we use consist of a Quartz Envelope encapsulating a tungsten filament
in an inert gas. This capsule is then mounted in a ceramic connector which allows it
to be plugged into the lamp holder in a lighting fixture. Lap bases, the connectors,
vary greatly in style. Most of the one we use are Bi-pin, i.e. they have two pins to
connect with. On a lot of lamps these pins are usually different size so you need to
make sure they are fitted the right way are you will irreparably damage the lamp
older.
Some lamps have built in reflectors, some don’t.
into the case.
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IT IS VERY IMPORTANT THAT WHEN CHANGING QUARTZ LAMPS
YOU DO NOT TOUCH THE QUARTZ GLASS AS THE GREASE FROM
YOUR FINGERS REDUCES THE LAMP LIFE AND MAY CAUSE THE
LAMP TO SHATTER IN USE. ALWAYS HOLD LAMPS BY THE
CERAMIC BASS OR IN A CLEAN DRY CLOTH.
USSU Stage Crew currently recycles it dead lamps. Dead lamps should be placed,
without smashing into the dead lamps bin in the workshop. Do not place smashed
lamps in this bin. Some lamps are delicate, and some are very heavy just because
the heavy lamp survived the lamp you dropped it on may not have.
4.2.2 REFLECTORS
Why do we use reflectors in stage lights? If we didn't, the only light we'd get out of a
stage lighting fixture would be the light radiated from the lamp in the direction of the
stage. Since our goal is to achieve the highest level of efficiency, reflectors enable us
to capture and use light beams which would otherwise be lost.
Stage lighting fixtures use several types of reflectors. Almost all use specula
reflection. These are the most common:

ELLIPSOIDAL REFLECTOR An ellipse is "a closed curve, generated by a
point moving in such a way that the sum of its distances from two fixed points
is constant." An ellipsoid is a 3dimensional ellipse. An ellipsoidal reflector has
two focal points; light rays originating at one focal point converge at the other.
An ellipsoidal reflector is actually ½ of an ellipsoid.

SPHERICAL REFLECTOR Spherical reflectors reflect all beams which strike
the reflector from or through the centre of curvature back through the centre
of curvature. This is indicated by the red lines and arrows in the drawing
below. The focal point is at 1/2 the radius of the sphere. As with parabolic
reflectors (see the section below), any beam that passes through the focal
point and strikes the mirror will be reflected out in parallel rays. This is
indicated by the amber lines and arrows in the drawing below.
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PARABOLICREFLECTOR Parabolic reflectors reflect all beams which strike
the reflector from or through the focal point out parallel to each other in a
beam of light approximately the diameter of the reflector.
4.2.3 LENSES

PLANO-CONVEX LENS: A lens curved on one side and flat on the other. The
more pronounced the curvature of the convex side, the closer to the lens will
be the point at which light rays entering the lens from the convex side will
converge. The distance from the lens to this point is called the focal length.
A plano-convex lens is described by its diameter and focal length. For
example, a 6"x9" lens will have a diameter of 6" and a 9" focal length. The
shorter the focal length, relative to the diameter of the lens, the wider the
beam of light; thus, a 6"x12" lens will emit a beam of light 3/4 the width of the
6"x9" lens. When two plano-convex lenses are used "belly-to-belly", their
effective combined focal length is halved. For example, two 6"x9" lenses
belly-to-belly will have an effective focal length of 4½". Fixtures using planoconvex lenses typically project sharp edged images:
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STEP LENS: Plano-convex lenses with the flat side cut away in steps. Step
lenses are optically similar to plano-convex lenses, but lighter and less prone
to cracking from the heat. The light from a step lens is usually not as even as
that from a plano-convex lens.
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FRESNEL LENS: Fresnel lenses, as opposed to step lenses, are cut away
from the front. They are extremely thin and therefore efficient and less likely
to crack from heat. Unlike step lenses, each of which has a single focal
length, each concentric ring of a Fresnel lens has a different diameter and a
slightly different focal length. Fixtures using Fresnel lenses project softedged
images.
4.2.4 SHUTTERS AND IRISES
Both shutters and irises are used to control the beam shape of a light.
SHUTTERS – These are metal blades (usually four) positioned within the optical path
of a spot light. They are used to block parts of the beam and therefore shape the
light coming out of the fixture. They are typically adjusted by handles protruding from
the fixture. Due to the optics of the fixture the blade position is the reverse of the
effect it has on the light. The blade at the top of the fixture will shutter the bottom
edge of the beam, the bottom blade shutters the top edge of the beam, the left blade
shutters the right edge of the beam and the right blade shutters the left edge of the
beam.
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IRISES – Irises are mechanical devises made of many interlocking fingers that mimic
the action of the iris in the eye. The fingers can be adjusted to open or close the
diameter of the aperture though which the light passes. By adjusting the iris in a light
the resulting bean width of the light leaving the fixture maybe reduced. Irises are
often an option that can be inserted into a light in a similar manor to a gobo holder.
Larger lights such as follow spots usually come with a non removable iris fitted.
4.2.5 GOBOS
The gobo, one of the oldest stage lighting effects, is still one of the best, cheapest
and most versatile even today. A gobo is traditionally a piece of metal, with shaped
holes cut into it that produces a pattern of light. The design of the pattern can be
anything, from abstract shapes to a sign or logo, and mounted in a holder which is
inserted into a spotlight at the focal centre (known as the “gate“) between the lamp
and the lenses.
TYPES OF GOBO:
METAL GOBO – The traditional stage lighting gobo is made from sheet metal that is
cut out to produce the gobo pattern. The metal gobo masks out areas of the
spotlights beam and are held in place in the spotlight using a gobo holder. Gobo
manufacturers are able to cut very intricate designs out of the metal although some
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areas of a pattern design have to be connected by a small tag. Metal gobos are the
cheapest way of producing patterns in stage lighting and, when used well, still look
great.
GLASS GOBO – These gobos are made from glass with the gobo pattern etched
using aluminium or other coating to mask out the light. This means that even more
complex images, with no metal tags, can be projected. Glass gobos are fitted in
special gobo holders and are extremely fragile. They are only designed to be used
facing one way in the spotlight so when you buy one, tell the vendor the make of light
so that the image is projected correctly. Glass gobos can crack in use if not heated
up gently in the spotlight or if the beam is focussed with a “hot spot” in the centre.
FULL COLOUR AND DICHROIC GOBOS – These gobos are made out of special
glass and use a variety of techniques to enable partial colour or even full colour
images to be projected. They are quite expensive and fragile so care needs to be
taken when using them.
GOBO DESIGNS
Gobos are available in a multitude of designs. Some are abstract patterns while
others include text, logos and graphic designs. A popular and effective theatre stage
lighting effect is to use “break up” gobos, blotchy patterns that produce a random
texture of light, and leafy patterns to suggest the light coming through a tree canopy.
Other natural gobo designs such as clouds, water and even a moon are useful.
More pictorial gobo designs such as light from windows, street signs and even
“happy birthday” (can’t say I have ever used that!) are sometimes required and gobo
manufacturers such as DHA or Rosco have a massive stock of gobo designs
available “off the shelf”.
Custom Gobos
If you can’t find exactly what you want then you need a custom gobo. A gobo
manufacturer will take your design and create one or more gobos to suit you in the
size that you require
Useful Things You Might Not Know About Gobos:

When trying to get a gobo image REALLY sharp, try to get the light source as
close as possible to 90 degrees to the surface you are projecting onto and
use a narrow spotlight.

You can improve a blurry gobo image by tweaking the lamp tray of you your
spotlight. If you adjust the lamp so it is not so hot in the centre, the image will
improve.

The wider the angle of your spotlight is, the less chance you have of getting a
sharp image all the way across the pattern. Any spot wider that about 30
degrees and you will only ever get one part of the gobo image to sharpen up.
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
If you are projecting breakup or clouds you won’t care about a sharp image.
Focus a zoom profile spotlight as small as you can get away with (this makes
sure you get the most light possible out of it) and sharpen the gobo image
using the rear lens. When you are happy with the image size, experiment with
“blowing” the focus to either side of pin sharp to get your desired look.

Break Up gobos and leafy patterns look even better using split colour gels.
Use a diagonal 4-way split with two or more colours and experiment with the
focus.

Fixed (single lens) spotlights will always focus a gobo better than a zoom (two
lenses) but you won’t be able to adjust the image size. All zoom profiles have
an optimum focal length where your gobo looks really great, often at it’s
medium beam angle.

When using glass gobos, try not to peak the lamp with centre hot spot as it
can crack the gobo as it heats up. Also, when you dim up a glass gobo for
focussing, don’t just stick in at 100%. If you don’t run a glass gobo at full and
heat it up gently in should not crack. During your show you can always pre
heat the gobo at 20% – 30% just to keep it warm until you need it.

If you have ever wondered what the little notches around one side of a metal
gobo are, they are for rotational adjustment. The gobo is supposed to be
mounted in gobo holder with the notches pointing up to the gate opening.
Using a screwdriver it is possible to slightly rotate the gobo in it’s holder for
better image alignment. Most stage lighting spotlights these days have
rotating lens tubes which make this unnecessary.
4.2.6 GELL FRAMES & HOLDERS
Gel or filter is the most common method used to colour light. It is a thin plastic sheet.
The sheet on its own is difficult to attach to fixture. We therefore use GEL FRAMES
to hold the sheet of gel (See bellow) and then mount the frame in the fixture. With
most lights the gel frame mounts on the front of the light in specially designed slots
referred to as gel runners. Some lights, for example follow spots, will typically
replace a single gel frame with a magazine of frames which mounts on the gel
runners and allows an operator to change the light colour during a performance.
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Some lights have multiple runners to allow both a gel frame and other accessory, i.e.
barn doors (see bellow), to be mounted to the light. A second gel runner may also be
used to hold a special heat shield (a plastic sheet similar to gel but optically
transparent to visible light which reduces the transmission of heat from the fixture
onto the gel sheet in front.) Heat shield is often used on up-lighters or highs with
dark gels which are more prone to heat damage.
It is often practice in theatre environments to use Gel Scrollers. These are remotely
controllable magazines that contain a sloop of multi colours gel. The gel is wound by
motor from one spool to the other to place different gel colour in the beam of light.
USSU Stage Crew does not own scrollers and it is unlikely you will use them with us..
4.2.7 BARN DOORS
Barn doors attach to the front of a Fresnel type lights in a similar manor to a gel
frame. They are a set of four leaves, two larger and widening on the outside, two
smaller and getting narrower towards the outside. They allow the beam of light from
the fixture to be shaped, and prevent the distinctive scatter of light created by the
Fresnel lens from spilling into areas where it is not wanted, such as the eyes of
audience members.
Barn doors are generally not used with "profile" or "ellipsoidal reflector" spotlights
such as the Source Four because they have internal shutters which work more
effectively. Barn doors are sometimes used on PAR lights, to shape the field of light,
although often a narrower lamp would be a better way to do this.
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4.3 PHOTOMETRICS
Photometrics is the broad term used to describe the measurement of the properties
of light, with specific attention being paid to the intensity of light. In general terms as
far as we are concerned you need to be aware to two relative effects.

The further a light source is from the object, or surface, it is lighting (the longer
the throw of light) the less intense the light is when it reaches the object. If you
double the throw you will quarter the intensity of the light.

The further a light source is from the object, or surface, it is lighting the wider the
beam spread will be when it reaches the object.
The spread of the beam of light may be calculated for a given throw distance if you
know the beam angle of the light. This is easy to calculate using some very basic
trigonometry but is beyond the scope of this training.
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5. CARING FOR YOUR LIGHTS
This section gives a basic guide to cleaning and maintaining your lights so you get
the best performance out of them. All the following tasks should be completed with
the fixture unplugged and when it is cold.
5.1 CHANGING LAMPS
Always allow a lamp to cool before changing it. Make sure the fixture is unplugged
before replacing a lamp. Remove to original/failed lamp from its holder. Design of
fixture varies so gaining access to the lamp in different fixture will vary but is usually
fairly obvious. Equally types of lamp holders vary greatly, but most lamps we use
have a bi-pin style base and simple push into the holders. Hold lamps by the
ceramic bases were applicable. If you have to hold the glass/quarts capsule of the
lamp, do it with a clean cloth and not your fingers. Grease from you fingers on the
lamp capsule will dramatically reduce the lamps life and may even cause a lamp to
explode as it heats up. Only put the type of lamp in a fixture that the fixture was
designed to take. Lamp types vary both dramatically and subtlety and the wrong
lamp may have many undesirable effects ranging from no useful light being emitted
up to the more significant fire risk. If you do unintentionally touch the glass capsule
of a quartz lamp clean the capsule with mentholated spirits or industrial alcohol to
remove the any grease.
5.2 CARING FOR OPTICS
Only clean the optics of a lamp when the unit is cold. Applying cold cleaning
materials to a set of hot optics can easily cause to optics to shatter. Lenses can be
cleaned by wiping with standard glass cleaner and a soft cloth. Do not apply
cleaning products to lamps as this will damage to lamps. If cleaning products are
accidently applied to a lamp the lamp should be cleaned with alcohol as described in
the previous section. Always allow a lamp to completely dry after cleaning before
plugging in and using the fixture.
5.3 CLEANING LAMP BODIES
Lamp bodies may be cleaned simple with a damp cloth when the unit is cold. It
should not require anything more abrasive to clean a lighting fixture as it is usually
only a build up of dust that is needed to be removed. As part of cleaning a light, any
moving parts that require lubrication should be lubricated with a suitable high
temperature lubricant. The service technician/ Technical manager should be
consulted before applying any lubricant to a light.
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5.4 ELECTRICAL CHECKS
The following basic check should always be carried out before using an item. They
are the same as for any other appliance. The following points should serve as a
reminder.






Check the condition of the fixture (look for cracks or damage).
Examine the cable supplying the item, looking for cuts, abrasions, cracks etc.
Check the cable sheath is secure in the plug and the appliance.
Look for signs of overheating.
Check that it has a valid label indicating that it has been formally inspected and
tested.
Decide if the item is suitable for the environment in which it is to be used.
If all these checks prove satisfactory, check that the light is working correctly. If you
feel that the equipment is not satisfactory, it must be switched off, removed from the
supply, labeled `Not to be used' or words to that effect.
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6 BUILDING YOUR LIGHTING RIG
So you have your lights and you know how to use them. You know what you are
lighting and how you intend to light it. Now for the easy bit, Put it all together and
light your subject.
6.1 RIGGING
This is largely cover by other training given by USSU Stage Crew and reference
should be made to this additional training. The following points are a brief reminder
of the key components to rigging lights:

Hanger or Clamp: Hanger should be used to hang lights. Clamps should be
used to attach lights in any other orientation. Always do clamps by hand
making sure they are tight and make sure they are attached to the lights
correctly as well.

Safeties: Always safety lights and accessories.

Make sure things are done up: Not just clamps and hangers but make sure
accessories are firmly attached and light are in a serviceable state and there
are no loose components

Cables come out of the bottom of lights: Always rig lights with the cable
entries at the base of the light. This reduces heat damage to the wiring. Also
ensure there is enough slack in the lamps cable to enable it to be focused.

Cable safety: Try and avoid excessive lengths of cable and coils of cable in
roofs. Were possible excess cable should be on the ground, but were there is
no option cable should be secured in the roof so that it will no fall from the rig.

Accessories: Treat accessories in the same way you treat the lights. The
same rules apply to both lights and accessories (i.e. barn doors, gel frames,
gobo holders, etc).

Make life easy: Make sure accessories are in lights before you put them in
the roof. Make sure lights are gelled when they are still on the floor Make
sure the shutters on a light are opened before you put the light in the roof.
Save your self time and effort and think about what you doing. Why walk up a
ladder three times when you only need to do it once if you think about it first?
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6.2 FOCUSING
6.2.1 POINTING OF LIGHTS
Focusing is probably the most important part of the whole lighting operation. Not
even the most sophisticated marvel of a microprocessor control desk can fill in that
dark spot where the lights have not been properly overlapped. Nor can a hard edge
be softened or a disturbing spill on to a border be shuttered off. Focusing involves
tricky ladder work so that there is every incentive to get it right first time - although,
inevitably, it will be necessary to get at the odd spotlight between rehearsals for a
little fine adjustment.
If you stand with your back to the light that you are focusing, (you will avoid being
blinded and you will be able to see what the actor's light is doing to the scenery)
1) No clear shadow of head, therefore the head is not lit.
2) Clear shadow of head, therefore the head is lit
3) If the lighting designer is shorter than the actor, make an allowance – check
by raising hand.
6.2.2 ADJUSTING LIGHTS
What can we adjust?
1. Position (ie left/right, up/down)
2. Beam Size (ie Bigger/Smaller)
3. Beam Shape
Most profiles have an adjustment whereby the light can be adjusted so that it is either
smooth across the whole spread of the beam, or 'peaked' to be brighter in the middle
with the amount of light falling off towards the edge. For most purposes it is easier to
light with an even brightness across the beam and so it is recommended that anyone
beginning to work with light should use an even beam until through experience they
discover a need for a 'peaky' beam.
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7 DIMMERS
For traditional lighting, i.e. incandescent lamps, the lighting dimmer is one of the most
significant control tools. A dimmer is a device that varies the output of a filament light
source.
7.1 CONTROL INPUT
There are many types of control input used, the most common are analogue and
DMX.
 Analogue control was for many years the only way of operating dimmers and
early intelligent fixtures. One core of cable is required for every channel. This
method is perfectly good over a limited number of channels, as intelligent
lights became popular rigs grew to hundreds or thousands of channels. The
main advantage of analogue control is the dimming is instant. IMPORTANT:
Analogue kit is not always intercompatible, common ranges are 0-10V (most
common), 0- -10V, 0-15V and 0- -15V. All USSU kit is 0 – 10V.
 DMX is a standard created in 1986. It allows up to 512 channels to be
transmitted over a pair of cores. Its biggest advantage is that it reduces the
amount of cabling. The main disadvantage of this technique is that there is a
slight delay between the desk and the light coming on. Common compatible
protocols involve using a three pin XLR or swapping the hot and cold pin
(phase reversing)
A number of other standards have been developed and are used (e.g. ART-NET,
RDM). These are either proprietary or aren’t widely supported.
7.2 CONTROLLED OUTPUT
The output of the dimmer is a non-linear increase in voltage. Most dimmers have a
pre-heat to warm the lamp element so it doesn’t suddenly go on get very hot and
break. As a result just because a light isn’t on it does not mean it is safe to go inside
it.
7.3 OUTPUT PATCHING
A lot of dimmers allow you to patch the output. This means that you can decide
where you want the light to appear. This has two purposes. In analogue desks
especially it allows you to decide what order you want the lights in on the desk. This
is less important as that can be changed on the desk. The second and more
important purpose is to phase balance the output.
Many dimmers work using 3 phases. You want to avoid putting all your lights on the
first phase then nothing on the second or third phase. This is most important for
generators as they require the current draw to be even across the 3 phases to work
nicely. Below is a list of hints for patching and phase balancing:
 Think about what lights you are going to turn on:
o If you have a number blinders which are going to be turned on
simultaneously spread them across the three phases. That moment
you initially turn them on will draw a lot of current this might be above
the maximum on one of the phases but spread out will be perfectly
happy.
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o



You will often find yourself turning lights of the same colour on
simultaneously, don’t put all lights of the same colour on a single
phase.
Different lights require different amounts of power. Make sure you have some
idea of the power requirements of your lights before patching. USSU own lots
of parcans, but some of these are 300W some are 500W and some are
1000W etc. If I patch 300W to phase 1 500W to phase 2 and 1000W to phase
3. It is obvious phase 1 has less on it than phase 3.
You can put more lights in your rig than you have power for. This is a
perfectly legitimate thing to do. Just don’t turn all the lights on at once. If you
end up using someone else’s lighting rig never turn all the lights on at once
without checking this is possible!
All cables are delicate, this is especially true of patch leads. While plugging in
and unplugging patch leads don’t just pull on the flex. Take hold of the plug /
socket.
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8 CONTROL DESKS
The lighting control desk is the key part of any stage lighting set up. Using the lighting
desk that an operator is able to control the lighting equipment. This can range from
adjusting the “levels” on stage lighting dimmers to controlling complex intelligent lighting
fixtures and media servers. Although there are many different types of lighting control, a
great deal of the features are common to most.
8.1 WHAT THE KNOBS DO
Lighting desk vary from model to model and between manufacturers, but all desks
follow a few simple layouts and methods of control. Some common features are
outlined bellow. Generally the best way to find out what a lighting desk can do it to
read the manual. Yes I know this is usually the last resort, but as far as lighting
desks are concerned this is something that is well worth doing as you will probably
discover just how powerful a desk is and how simple it can make your life.
8.1.1 Channel or Preset Controls
Even the most basic lighting desk has a degree of channel control. This enables the
operator to adjust the “level” (sometime expresses as a percentage – 0% – 100%) of
a “control channel”. A lighting desk controls this channel which can be used to adjust
a range of lighting equipment, traditionally, the intensity of a stage light via a dimmer.
A modern lighting desk controls these “channels” using different input methods such
as faders/sliders for intensity, numeric keypad (where you type in a value) and
wheels. These wheels give the operator the ability to adjust parameters and levels,
particularly in the control of intelligent lighting. Where lighting intensity is controlled by
faders, an additional “flash button” is useful for quick flashes of each channel.
8.1.2 Master Controls
The master control faders on a stage lighting desk adjust the output channels levels
on a global scale. The Sub Masters, or Memories, can control different groups of
lighting channels while the Grand Master adjusts the intensity of every channel as it
leaves the lighting desk. It is worth remembering that, on a lighting desk with
intelligent lighting control, the Master control faders only actually adjusts lighting
intensity level channels and not other effects channels.
8.1.3 Playback
“Playback”, is a term used to describe the “playing back” of different scenes, looks or
states during the show. At it’s simplest, playback is simply setting the channel faders
on the desk to a given level and then fading up the relevant Master Control so that
the result appears on stage. Lighting desk’s that have two set of preset faders
(channel faders) with enable you to set your next scene up on another set of channel
controls and then cross fade that scene in when required. More sophisticated lighting
desks have a number of playback features:
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Memory Playback – Stack Control
Even simple lighting desks have often a degree of Memory Playback which enable
the operator to record “memories” of different scenes and their channel levels and
then play them back using a fader. These scenes can be faded in and out using a
prerecording time or timed manually by the opperator. Some lighting desks, more
commonly theatre desks, play back scenes using “sequence control”, also known as
a “theatre stack”. In a “theatre stack”, each scene is played back in numbered order
every time the “go” button is pressed and, as the name suggests, this system is
common in theatre shows where the cue sequence should be the same every night.
Memory Playback – Sub masters
An alternative way to playback lighting scenes is to use Sub masters. Each sub
master on the lighting desk can have a memory recorded “onto” where the scene can
be faded in and out using the sub master and even added to the output of another
sub master memory. This gives the lighting operator better control and ability to mix
and match the lighting states on the fly. The number of actual physical sub master
faders on a lighting desk is often increased by using multiple pages of subs that each
contains a different lighting state. There are quite a few lighting desks that have sub
masters in addition to stack control and a “Go” button and these can be useful for
manually operating some cues such as houselights/tab warmers etc.
Effects Control
Effects Control is a feature of a lighting desk that has some kind of automated
generation of lighting effects. This can be simple chases or complex generation of
intelligent lighting effects that would be time consuming to produce by traditional
programming. Chase effects can be triggered by a sound signal, as well as altered
using different timing and chase patterns. Lighting desks with effects control often
use one or more separate master faders for overall control of the effects output.
8.2 LIGHTING DESK OUTPUT
How a lighting desk controls your rig depends on what kind signal it outputs to the various
bits or equipment that it “talks” to. Some basic dimmers use varying analogue voltages to
interpret their channel “levels” right up to high end professional desks that use an
Ethernet network like a PC.
The standard in stage lighting control is the DMX512 protocol. Digital Multiplex
(DMX) was developed as a standard digital theatre lighting control which replaced
the older analogue systems that were used to control the dimmers in a stage lighting
rig. Despite the advance in use of Ethernet networking at the top of the professional
lighting industry, DMX is still the best answer for most lighting control applications.
DMX had the advantage in that a total of 512 (hence the name DMX512) dimmer
channels could be controlled using only a 2core and Ground signal cable. The other
plus point to DMX was (and still is) the fact that a signal cable could be daisy chained
from one DMX unit to the next and the next until all the lighting equipment was
connected by one single chain of signal cables. This is particularly important when
controlling moving lights as it minimises the cable required.
Information about each DMX Channel (in the old days, a dimmer number) and it’s
level (0 – 100%) is transmitted down the DMX Universe cable and each DMX stage
lighting fixture, moving light or smoke machine listens for it’s own part of the signal
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stream and ignores everything else. The signal is then transmitted over and over in
packets, giving a regularly updated stream for the rig to obey. The lighting console
receives no information in this one-way street.
In order for all the DMX stage lighting fixtures to have their own part of the signal
stream, each one has it’s own address which is set on the fixture using buttons or
switches. If a dimmer channel has a DMX address of 001 then it listens for the 001
part of the DMX signal then obeys the channel level value, 75% for instance. Once all
intelligent lighting fixtures, dimmers and accessories are connected up and
addressed the lighting desk can control each part of the rig individually using their
own unique DMX address.
Back when we only controlled dimmers using DMX, life was simple. 1 DMX Channel
= 1 Dimmer No. Then we started to use more complicated fixtures, moving lights and
intelligent lighting that needed more than 1 DMX channel per fixture. This means that
fixtures are assigned a DMX start address which is the first channel in a sequential
batch that the fixture listens to. If your fixture uses 6 DMX channels and you set it to
a start address of 001 then it listens to channels 001,002,003,004,005 and 006. Your
next free address for another fixture is then 007 because if you set it to 006 then the
channel overlap would create a conflict of control. Setting fixtures to the same start
address can be useful some circumstances and is a common method of DMX fault
finding.
With many DMX moving lights requiring the use of 20 or more channels, those 512
don’t look too many now, huh? A few moving lights, 100+ Dimmers, Strobes and a
couple of smoke machines and you’ve run out of channels already! The solution to
this problem is to connect and address some of your equipment on a second DMX
universe, a different signal stream with even more cables. Many lighting control
desks have more than one DMX output these days and the principles of fixture
addresses and channel numbers apply to this, and subsequent, universes. The first
DMX channel on a second universe is also 001 and each DMX universe is a totally
separate stream, independent of each other.

It does NOT matter which order you connect up all the fixtures in a DMX
chain, so long as they all have a signal going to them.

A DMX signal cannot be split into two using a Y-split cable. A DMX
splitter/buffer is required.

If does not matter which order your fixtures are addressed in just as long as
they are unique and don’t overlap.

Make sure you find out how many DMX channels each of your fixture uses for
control.

A DMX chain will usually work without a termination resistor although it is
recommended by the equipment manufacturers and can solve some tricky
problems with a complex rig.

The “DMX received” indicator on a piece of equipment does not necessarily
mean that all is well with your DMX signal.

You can set two pieces of DMX equipment to the same start address on the
same universe without problems. They will both do exactly the same thing.
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8.3 INTELLIGENT LIGHTING DESKS
Intelligent lights, moving or not, can have a large number of parameters that must be
controlled. Although it is possible to control a DMX intelligent lighting fixture using the
simplest manual DMX desk, it is not desirable. This is largely due to the fact that the
complex features that an intelligent light has to offer cannot be best used running a
lighting desk with no intelligent control interface. The user interface makes
programming a chore and command of large numbers of fixtures becomes difficult
particularly for the beginner. The other reason that makes controlling intelligent
lighting using a traditional “generic” lighting desk is the way that cues are played
back. Simple conventional lighting desks use Highest Takes Precedence (HTP)
playback that is ideal for controlling dimmers and light intensity. Intelligent lighting
parameters such as position, colour, gobo etc. benefit from being played back on a
Latest Takes Precedence (LTP) basis which makes for better control of cues and
scenes. So, having established that we need some specialised intelligent lighting
desk control in order to effectively program and playback intelligent lighting cues,
there are some common features to all lighting desks designed for this purpose.
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9. INTELLIGENT FIXTURES
Intelligent fixtures are being increasingly used in lighting rigs, and in some cases
exclusively used. An intelligent fixture on the hole is just a way of packaging a lot of
the features seen in other types of light in one convenient box. So instead of
powering my light, adjusting the focus putting in a gobo or shuttering it. I can power
up my light and control these features from the lighting desk. It also provides
flexibility, where I might have required four lights to pick out four different areas of the
stage at different times, this can now be done with a single light which moves
between these places and focuses for each one.
As a result of this there is the possibility to find many creative ways of using
intelligent lights.
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