theatrical design and production chapter 14: lighting production © 2006 mcgraw-hill. all right...

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




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




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




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




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




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




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




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




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




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




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




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




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




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




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





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





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





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





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





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





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





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





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




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





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





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




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




Dimmers


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




Dimmers


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




Dimmers


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




Dimmers


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




Dimmers


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




Dimmers


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




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





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





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





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




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




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




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




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

theatrical design and production chapter 14: lighting production © 2006 mcgraw-hill. all right...

Documents

lighting production

production chapter

theatrical lighting

theatrical design

lamps incandescent lamp

lighting instrument

lamps lamp structure

lamps color temperature