Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lighting designers and those involved in technical production need to have a thorough working knowledge of both electricity and electronics
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lenses
Double Plano-Convex Lens Train
This consists of two plano-convex lenses placed with their convex surfaces toward each other
This double configuration provides the same optical properties as a single lens of greater thickness and curvature, and the total thickness of the two lenses is less than the thickness of the optically comparable single lens
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lenses
Step Lens
A step lens retains the optical characteristics and shape of a plano-convex lens, but the glass on the flat side is cut away in steps
The stepping process gives the lens the optical properties of a thick, short-focal-length, plano-convex lens while eliminating its negative characteristics
Finishing the edges of the steps with a flat-black ceramic coating eliminates the spectral breakdown
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lenses
Fresnel Lens
The Fresnel lens is a type of step lens with the glass cut away from the convex face of the lens instead of its plano side
The advantages of this lens include reduction of the thickness of the lens, which allows more light transmission and lessens the chance of heat fracture
Fresnel lenses are primarily used in Fresnel spotlight
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lamps
Incandescent Lamp
The standard incandescent lamp contains a tungsten filament that is place in an inert gas environment inside the lamp bulb
The average life expectancy of a regular incandescent lamp used in stage lighting is 50-200 hours
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lamps
Tungsten-Halogen Lamp
The T-H lamp is primarily the same as the standard incandescent lamp except that the atmosphere inside the bulb is a halogen, or chemically active, gas instead of inert gas
Many T-H lamps designed for stage lighting are rated from 150-2,000 hours
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lamps
Arc Sources
An electronic arc that produces brilliantly blue white light is created when an electric current jumps the air gap between two electrodes
An arc is used as the source of some followspots
Neither arc nor encapsulated arc sources can be dimmed, so they are normally not used in nonautomated stage-lighting instruments
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lamps
Color Temperature
All the standard light sources appear to be white; however, they are actually a variety of colors
These colors can be identified using the color-temperature scale
The color-temperature scale is measured in Kelvin (K)
The higher the light output of a lamp, the higher its color temperature and shorter its rated life
Instruments that are “gelled” are generally equipped with lamps of the same color temperature
Gel—to put a color filter into a color frame and place it in the color-frame holder of a lighting instrument
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lamps
Lamp Structure
All lamps are composed of three basic parts
Bulb—the Pyrex or synthetic quartz envelope that encases the filament and acts as a container for the gas-filled atmosphere of the lamp
Base—the lamp base secures the lamp in the socket and provides the electrical contact points between the socket and the filament
Filament—for stage lighting, the lamps are make of a tungsten-wire, tightly coiled, and strung in one of the general configurations
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lamps
MR16 Lamps
Small-diameter, low-voltage, low-wattage lamps that integrate a small, coiled-filament tungsten-halogen lamp into a focusing mirrored reflector
It is available in a variety of voltages and wattages as well as several beam-angle widths from very narrow to flood
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lamps
Light Output of Lamps
The light output of an incandescent lamp is primarily a function of the size and composition of the filament
This output is measured in lumens
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lamps
Light Output of Lamps
Color Media
Plastic—the majority of filters used in theatrical lighting are made of either Mylar or polyester because of the rugged, long-lasting, heat-resistant qualities of these plastics
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lamps
Light Output of Lamps
Color Media
Glass
These filters are used infrequently because they are heavy, expensive, and shatter if dropped
They are most often used in roundels, the glass filters used with striplights
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lamps
Light Output of Lamps
Color Media
Dichroic
They are a relatively new addition to theatrical color media
While plastic and glass filters allow their color to pass through the filter while absorbing the undesired color, dichroic filters reflect the unwanted colors
To produce a particular color, you use the filter to remove its complementary
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lighting Instruments
Ellipsoidal Reflector Spotlight
This light has a narrow beam width and is capable of traveling long distances
Known as a Leko, the quality of light produced is hard edged with little diffusion
The shape of the light is controlled by internally mounted shutters
The spill from an ERS is minimal
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lighting Instruments
Ellipsoidal Reflector Spotlight
Accessories
Color frame — a lightweight metal holder for plastic colored media
Gobo—a lightweight metal cutout that turns the ERS into a pattern projector
Iris—a device with movable overlapping metal plates used to change the size of the circular pattern of light
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lighting Instruments
Fresnel Spotlight
This spotlight produces a soft, diffused, luminescent light
The standard Fresnel spotlight is equipped with a Fresnel lens producing a circular beam of light
Oval-beam Fresnel lenses produce an oval beam of light
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lighting Instruments
Fresnel Spotlight
Accessories
Barn door—movable flippers swung into the beam to control the spotlight
Funnel—masks the beam to create a circular pattern, also called a snoot or top hat
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lighting Instruments
Striplight
This light is used to create a smooth wash of light
It resembles a long trough with a series of lamps inside
The individual lights within the instrument are wired in parallel to form three or four circuits, allowing for mixing and blending of color
Striplights are primarily used to light background drops and cycloramas
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lighting Instruments
Cyc Light
The cyc light is superior to the striplight for creating a smooth wash of light over the expanse of a cyc or drop
The cyc light emits a much smoother light than does the stripight and is equiped with a color-frame holder so the light can be colored as desired
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lighting Instruments
Ellipsoidal Reflector Floodlight
Also known as the scoop, this light is used to light drops and cycloramas
It is a lensless instrument that provides a wide, smooth wash of light
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lighting Instruments
PAR Can
The parabolic aluminized reflector (PAR) is a sealed-beam lamp similar to the headlight of an automobile
The PAR can performs no function other than safely holding the lamp and its color media
It is used in dance and concert light and is finding increased usage in the theatre
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Lighting Instruments
Followspot
The followspot is used when a high-intensity, hard-edged beam of light is required to follow a moving performer
Portions of the system can be adjusted to focus the light and adjust the crispness of the edge of the beam
Some followspots are equipped with a dimming device called a “douser”
Followspots are also equipped with a color boomerang to control color
Douser—a dimming device that can be used to achieve a slow fade-in or out of the light
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Specialty Instruments
Low-Voltage Sources
A number of specialty lamps use a voltage lower than the 120 output volts of most stage dimmers
A number of lighting instruments and projectors have been designed to take advantage of the properties of low-voltage lamps
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Specialty Instruments
Intelligent or Kinetic Instruments
Moving light fixtures provide punch, emphasis, and focus
Kinetic fixtures and digital control equipment provide the LD with the capabilities to create the in-your-face lighting that supports the production concepts and mood of many concert productions
Kinetic fixture beams pan the stage, zoom in and out, change shape, change color, diffuse and sharpen, gobos materialize, spin around, and change patterns
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Specialty Instruments
Color Changers
Color changing is accomplished with either a color scroller or a dichroic color changer
The color scroller is used with an ERS, Fresnel, PAR, ,or any other instrument that doesn’t have internal color changing abilities
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Dimmers
Dimmer-Control Techniques
Mechanical Dimmer Control
Older types of dimmers require direct mechanical manipulation of an axle running through the central core of the dimmer to adjust the intensity of a lamp
This method of dimmer control is awkward
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Dimmers
Dimmer-Control Techniques
Electronic Dimmer Control
When you move a controller to increase or decrease the intensity of lights connected to an electronic dimmer, you are using a low-voltage control circuit to manipulate the high-voltage output of that dimmer
Until recently, analog control systems were the only method available, now digital is the standard
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Dimmers
Dimmer-Control Techniques
Autotransformer Dimmer
These dimmers increase or decrease lamp intensity by varying the voltage within the circuit
This type of dimmer is only rarely used to control stage lights, but houselights in some theatres are controlled this way
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Dimmers
Dimmer-Control Techniques
Silicon-Controlled Rectifier Dimmer
The SCR dimmer is the most reliable and efficient unit
The SCR dimmer operates on a gating principle, which is a rapid switching on and off of the power
These properties result in a dimmer that is rugged, long lived, compact, relatively lightweight, moderate in cost, and reasonably quiet in operation
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Dimmers
Dimmer-Control Techniques
Insulated Gate Bipolar Transistor Dimmer
The IGBT dimmer is the latest in the continuing line of dimmer development
The IGBT dimmer is lighter and quieter in operation than the SCR
It has a relatively slow power ramp which reduces the amount of filament hum of an y lamp being dimmed by it
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Dimmers
Dimmer-Control Techniques
Control Consoles
Group Master—individual dimmers are controlled by a submaster, which is subsequently controlled by a grand master
Preset—allows you to keep ahead of the onstage action by presetting the intensity levels for each dimmer before it is needed
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Dimmers
Dimmer-Control Techniques
Control Consoles
Combination—a fusion of the previous two, each dimmer channel has an associated switch capable of assigning the dimmer to preset, group-master, or independent control
Computer Memory—the standard for the industry, the computer electronically stores the levels of all dimmers on each cue
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Cables and Connectors
Electrical Cable for Stage Use
The National Electrical Code (NEC) stipulates that the only electrical cables approved for temporary stage wiring are types S, SO, ST, STO
These cables have stranded copper conductors and are insulated with rubber or thermoplastic
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Cables and Connectors
Wire Gauge
The American Wire Gauge (AWG) system rates wire according to the amount of current that a conductor of a particular size and composition can safely carry
The NEC stipulates that receptacles used to supply incandescent lamps on stage must be rated at not less than 20 amperes and must be supplied by wires of not less than 12 gauge
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Cables and Connectors
Connecting Devices
Several different styles are used in stage lighting
Twist-lock connectors
Pin connectors
Grounded pin connectors
The Edison, or parallel blade, plug
The NEC stipulates that each plug should be equipped with an effective cable-clamping device to secure the connector to the jacket of the cable
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Cables and Connectors
Extension Cables
Extension cables can be purchased or made in the electrical shop in any reasonable length
A two-fer is used to connect two instruments to the same circuit
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Circuiting
Permanent Wiring
The simplest method is to permanently wire the instruments to the dimmers
To operate the system, you just turn on the dimmers
Although this method is easiest to operate, it provides little flexibility and does not allow for much creativity
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Circuiting
Spidering
Also known as direct cabling, it involves running a cable from each lighting instrument directly to the dimmer to which it is assigned
Used extensively in Broadway theatres and on tour, it provides the greatest flexibility because it allows the designer to put an instrument wherever it is needed
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Circuiting
Connecting Strips and Patch Panels
Two advantages:
The light plot can be hung and circuited quite rapidly
The system provides a great deal of flexibility by enabling you to patch any circuit into any dimmer
Theatrical Design and Production
Chapter 14: Lighting Production
© 2006 McGraw-Hill. All right reserved.
Circuiting
Dimmer per Circuit
The dimmer-per-circuit configuration combines the efficiency in hanging and circuiting of the connecting strip with the ease of operation of the permanently wired system
The onstage end of each circuit terminates in an outlet on a connecting strip
The other end is directly wired to a dimmer