How Do We Control?

A Basic Theatrical Lighting System

In order for artists in the theatre to begin to manipulate light, they have come up with different lighting systems.  A lighting system can be as simple as a lamp being plugged into the wall or a light being switched on by a singular light switch.  However, if you want to be able to control all of the properties above you will need something a little more sophisticated.  Let us look at what comprises a basic theatrical lighting system.  Remember, that since there has been a long evolution of equipment in the past few decades each theatre will be different.  Theatres are usually under budgetary stress and cannot upgrade every time a better piece of technology comes out.

Most lighting systems will include:

The Hanging Location

Where you locate the light. This establishes what direction the light beam is coming from.  In established theatres these are generally permanent locations.  In other venues you may very well setup your hanging location on the spot and where every you need and have access to.  For more information, see Where to Put the Lights.

The Lighting Unit

The actual instrument that produces light. Here you can change the color, shape and sharpness. Most fixtures accommodate color filters to change the color. The reflector creates the shape of the light. The shape can be adjusted via shutters, irises and barn doors. The sharpness can be changed with different relationships between lenses and reflectors.  For more information, see Lighting Units.

Power Distribution

The light needs power. This is how the electricity gets from the dimmer to the light. It can be as simple as a lighting cable (heavy-duty extension cord) from the dimmer to the light, or as complicated as a patch bay that assigns circuits to chosen dimmers.  A power distribution system may also include raceways, which permanently place circuitry throughout the theatre.  For more information, see Lighting Cable & Electrical Distribution.

Intensity Control – Dimmers for Conventional lights and Built In Intensity Control for LED units.

The dimmers are controlled by the control board (light board) and are the physical units that either let all of the electricity get to the light, causing it to go to full, or restrict the electricity to the light, causing it to dim.  Dimmers are used for conventional lighting units, not LED units.  For LED units the intensity control is built into the unit.  You send a control cable with the control signal from the light board to the LED fixture.  With more and more LED units being used, it is very common to split the control signal with data splitters.  This way, the cabling doesn’t get too crazy.  It is also very common to send a signal line to each hanging location, and then have the control signal daisy chain (hold hands) from unit to unit.  For more information, see Dimmers.

Control

The control is the brains of the system. The light board, whether manual or memory, is controlled by the human. Once the control board knows what should happen it sends a signal through control wires, or wireless signals, to the dimmers and other controlled devices.  The most common control signal today is DMX-512.  It is a digital signal that connects all devices that receive control information. For more information, see Controllers.

The Flow of a Lighting System

The basic flow of a lighting system is:

For a conventional light with intensity controlled by a dimmer…

Control board > Control signal transporter > Dimmer > Electrical cable > Lighting unit

For a LED light…

Control board > Control signal transporter> LED unit (with constant power provided)

For a mixed system with conventional and LED units together…

Control board > Control signal transporter > Control signal splitter sending a signal to dimmers and then also to the LED unit > then continue on to the lights as listed above.

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