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Lighting

Basics

The main purpose of lighting is to make the talent visible! But lighting is also useful in setting mood, creating special effects, and even creating images.

It is important to remember that the lights are called Fixtures or Instruments. In theater we do not say light bulbs, we refer to them as Lamps.

        [Never touch a lamp with direct skin contact, whether hot or not. The oils from skin will rub off on it, then when the light turns on the oil will cook and the lamp will explode!!]

--And always remember that any fixture hanging overhead must have a safety cable attaching it to the structure or batten, so that if the clamp fails the fixture doesn't fall.

Another thing to keep in mind when deciding which light to put up is the Throw. This refers to the distance and angle the light needs to reach. Wider angle lights have less punch and cover wider areas than narrower lights.

Instruments can be hung from the pre-made Electrics in a theater, which are battens rigged with electrical boxes specifically for lights. Bumpers are large rings that can hung from the electrics to avoid what is playfully called "carpenter focus", which means a nearby fly-line struck a light in travel and changed the direction it was pointed. Instruments can also be hung from normal battens, trusses, or fixed pipes. Over-stage light is typically used for Back-light or Top-light.

At Front of House, there are Catwalks or Coves hanging over the audience. From these we hang instruments for Front Light.

There is also a Followspot Booth (at the PCC there is a rail on either side of that booth from which lights are hung called the Spot Rail) and the Balcony Rail.

Box Booms are typically at a 45 degree angle from the stage, over "opera boxes".

Lighting theory is mostly based on the McCandless 45 degree rule. This states that optimal lighting happens when the actor is lit from front, back and sides at 45 degree angles. This not only makes the actor easily visible, but gives him/her a three dimensional look. This theory is only a guideline of course; every show calls for a new creative ideas.

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Color

When discussing pigment, we are talking about mixing color through subtractive means. The more colors you add together, the darker it gets: less light. The three basic colors of pigment are red, blue and yellow.

But when we are discussing light, color mixing is (mostly) additive. The three basic colors of light are blue, red and green. If you add light of all colors together, you get white light, which is the brightest.

Hue refers to what color you are looking at. Saturation refers to how much of that color is in the light - is it a very pale pink or a very deep pink?

Color Temperature is a temperature figure, given in degrees Kelvin, that describes the "whiteness" of near-white light. The higher the color temperature, the "cooler" the light. Lower color temperatures have "warmer" light. Lamps (not bulbs) of the same kind can have different color temperatures, and this is often a result of the age of the lamp.

Color can be achieved a few ways in lighting.

The most common way is add colored filters called Gels to the fixture. (Gels used to be made from gelatin, but are now made from heat-resistant plastics.)

Gel comes in hundreds of colors from various companies, and the more saturated the color, the quicker it will absorb heat - therefore melt or lose saturation. "Frost" Gel is a way to spread and soften a fixture's beam. Remember that when loading a color and a frost into a fixture, make sure the light will pass through the frost before the color. When done in reverse, the color can bleed into and stain the frost.

A dichroic filter, which is a thin-film filter, is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors. By comparison, dichroic mirrors and dichroic reflectors tend to be characterized by the colors of light that they reflect, rather than the colors they pass.

The method that is quickly becoming the most common is LED (light emitting diode) lighting. LED's put out light at a specific wavelength for the color desired. They are very electrically efficient, put out little heat, and have a relatively long life.

Types of Fixtures

Types of Lights

The three primary categories of lights are Conventionals, Intelligents, and Follow-Spots.

Conventionals (and most follow-spots) only require power cabling. Intelligent lights require running both power and data cables to them.

Conventionals:

Wash Light

Produces a soft edged beam which looks quite natural. Beam size can normally be adjusted and multiple sources blend together easily. There are a few sub-categories of these; fresnels, prism-convex and pebble-convex. The Fresnel is probably the most widely used of these.

Beam Light

The Beam Light is a little different as all the optics (reflector, lens, etc) are contained in the lamp (aka bulb). This brings the cost of the fixture down but the lamps are a little more expensive. The most common example of this fixture is the Parcan. These lamps produce a very intense beam of light which can be very effective although there is no control over the beam and the spread is a little uneven. Used extensively in Rock'n'Roll due to the intensity of the light which works well with strong colours.

Spot Light

Also known as a Leko, Ellipsoidal (due to the shape of the reflector inside), or Profile Spot. These have a more complex lens assembly and allow you to focus the beam so that you can have a soft edged beam like the wash light or a hard edged one. The shutters on the sides of the ellipsoidal light allow you to cut the light off of scenery or to just produce a simple box of light (remember that the reflector causes the shutters to go opposite of what you would guess). Most Profile spots allow you to insert a Gobo - a metal disc with cut-outs - to breakup the light or to project shapes and images. This can produce a variety of effects. They also have swap-able barrels so that you can choose the spread of the beam to fit your needs. Higher degree barrel means wider spread of beam.

Flood Light

Last, but not least, the flood light. This has no adjustable controls and produces a very wide spread of light. It is normally only used to illuminate backdrops. Cyc lights, sometimes called the Ground Row or strip lights, are examples of these.

Intelligents:

Intelligent lights can include various types of wash, including pars, strips, and beam lights.

The category also includes digitally controlled moving lights.

In addition to power, these require a data cable which uses a language called DMX to tell the lights what to do.

Follow-spot Lights:

There is a wide variety of types of Follow-spots and which ones you'll see depend on the needs of the venue - primarily how much throw is needed.

"Robo-spots" are becoming more common as replacements for truss-mounted follow-spots. These are operated remotes on the floor.

Fixtures are often stored on what we call "meat racks" for long term storage or transportation.

Any fixture hanging in the air should have a Safety Cable securing it to the pipe it hangs from.

 

Before letting an electric go out, double check that your wrench is not sitting on it!

Common Cables

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Cable Runs

As stated above, all conventionals require only power, which is provided by the Dimmer. It is called a dimmer because it has the electrical ability to provide a range of power between 1% and 100%, to allow a light to vary in intensity and transition smoothly.

But the board operator doesn't want to control every single light individually, that would be too time consuming for a show. Two or three lights can be circuited together on the same dimmer using a cable called a Two-Fer.

Once the lights are Hard-Patched into the dimmers, the light board takes control and the operator can Soft-Patch the lights to the channels desired. By having multiple lights in the same channel, the board-op can control many combinations of them. Channels can then be Grouped together or put onto Submasters to control even larger sets using faders.

Here is a diagram of patching lights, from hard-patch to soft-patch.

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Addressing

Each dimmer is an Address in the light board. Light boards work with Universes, each universe can handle 512 addresses. If you have more than 512 dimmers, you have to use a second universe.

But intelligent lights have to do more than just go on and off. Each intelligent light has information for intensity, color, and possibly beam and focus. So each intelligent light has multiple addresses.

This is where Digital Multiplexing or DMX comes into play. DMX can be jumped from one fixture to another until you have used up all of the addresses in one universe. The DMX signal goes to the first fixture and tells it to pay attention to the signal for addresses 1-10 for example. Then the signal continues down to the next fixture, which it gives information that pertains to addresses 11-20. And so on for the entire Daisy Chain.

It is sometimes a good idea to input a "terminator" cable at the end of the DMX run to tell the signal to stop, avoiding confusion in the chain.

When chaining fixtures together, the cables between lights are called Jumpers, and the cables that run back to the source of power or data are called Home Runs.

Home runs go to the dimmer racks, which are located, believe it or not, at dimmer beach, often stage right.

In the light board, this set of addresses for each intelligent is given a channel and a profile for the make and model of the instrument. This way the board knows which address pertains to which attribute of the fixture.

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Feeder Cable
is used to connect to the main power supply from the venue.

 

Large amounts of power are fed from the building into the touring dimmer racks by the feeder cable runs. This power is extremely dangerous and should only be connected by qualified stagehands (i.e. the head electrician).

But feeder jumpers will often be run and connected by stage hands.

It is important to note that the Ground wire (green connector) is the first line of defense in electricity. It provides a path for excess electricity to travel safely away from personnel.

Thus, anytime anything is plugged in, the ground must be first. And vice-versa when it is being unplugged.

The Neutral (white) is next, because it also provides a path for the power to leave. The three Hot-Legs (usually blue, red, and black) send high voltage into the building, and therefore should always be connected last and disconnected first.

To be clear: The order to connect is always  Ground, Neutral, Hot, Hot, Hot.

The order to disconnect is Hot, Hot, Hot, Neutral, Ground.

Of course, these should never be energized when making or breaking connections, so always confirm this with the head-electrician.

Electrics Load-In

  1. First we arrange the Power Distro and Dimmer Racks in Dimmer Beach.

  2. We run feeder to the power distro, and jump that power to the dimmer racks.

  3. We set up trusses/electrics battens with the fixtures. Types of trusses and fixtures vary; follow instructions and ask questions.

  4. We run power and data cables to the fixtures. Sometimes these will be individual cables, but often they will be in Looms or sets taped together.

  5. The Head Electrician makes sure the lights work, and then flies the lights to Trim.

  6. The riggers help with picking the cables out of the way from the pick-rails.

  7. Next will be the lighting Focus, which involves making sure every light is pointed the direction it needs to be for the show.
    Focus involves both climbing up to the coves and using the Genie-lift to focus overhead lights onstage.

  8. The final step will involve clean-up of all cables, empty cases and equipment onstage

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