The Essentials of Automated Lighting Design
This article is excerpted from the author’s “Automated Lighting, 3rd Edition,” published by Routledge and available here.
We eat light, drink it in through our skins. With a little more exposure to light, you feel part of things physically. I like feeling the power of light and space physically because then you can order it materially. Seeing is a very sensuous act; there’s a sweet deliciousness to feeling yourself see something.– James Turrell, artist known for his use of light in art
Designing with automated lighting is really not much different than designing with conventional fixtures. The same design goals typically apply, the techniques are very similar if not the same, and the results, if the designer has met the goals of the design, can be similar. The difference is that the capabilities are greater, the possibilities virtually limitless, and the results can be more spectacular.
The flip side of the coin is that indiscriminate use of automated lighting can be utterly disastrous. Since automated lighting first became commercially available, the same adage about using automated lights or some variation of it has been uttered many times.
The way Anne Militello of Vortex Lighting expressed it was, “Just because it can move doesn’t mean that it has to move.” The corollary to that might be that all movement and color change isn’t necessarily good; use them with purpose and discretion.
No one would begin a journey without first knowing where they want to go. The same applies to lighting design. Before beginning a new lighting design project, you should know exactly what your goals and objectives are and how you’re going to achieve them.
Before ever putting pen to paper or laying out a plot, you should have a list of priorities. Some of the more common lighting design criteria are outlined in the following sections.
Visibility is one of the most important goals of a lighting design. If you’re lighting a stage with a band or an actor, then the subject(s) should be illuminated sufficiently for the audience to see (Figure 1).
In some instances, facial features and expressions are very important, and in other instances the designer may choose not to reveal too much about the subject. Visibility should be quantified in terms of illuminance in lux or foot-candles (fc).
During the course of a show, it’s natural for people’s attention to drift. By keeping the stage and the subjects on it well-lit and keeping the peripheral areas at lower illuminance levels, more attention will be focused on the subjects (Figure 2).
Focusing attention is as much a function of lighting contrast, or the difference in illumination levels between the areas of interest and the areas of less importance, as it is a function of overall illuminance levels.
If everything in a space is lit to 300 fc, the eye has no focal point and there’s nothing to draw the eye or compel it to stay focused on the subject. If, on the other hand, the subject is lit to 150 fc and the rest of the room is lit to 25 fc, then the eye is more likely to stay focused on the well-lit subject rather than wander around a darker room.
Many shows are reinforced with live video, either in the form of image-magnification (I-mag) or “B roll,” which is pre-produced content for playback (Figure 3). If the show you’re lighting has video, then the lighting requirements could change dramatically.
The light levels, uniformity, color temperature, and direction of lighting are all subject to critique and debate by the video crew. It’s best to communicate with the video director before beginning the lighting design to find out their requirements and expectations. Find out about their expectations for light levels on the subject and on the set.
Modern video cameras are capable of producing good results with lower light levels but higher lighting levels still produce less grain in the picture. One of the biggest issues to deal with when video is involved is the uniformity of light across the stage, particularly if the subject moves around a lot or if there are many subjects spread across the stage.
If the light level varies from subject to subject or from one position to the next on stage, the video engineer will have to “ride the iris” or “shade the cameras” to correct the exposure levels every time the camera moves, and chances are they won’t be happy about it.
One of the main objectives of lighting design is to give form and definition to the subject by “modeling” it with light. That simply means to accentuate the shape, texture, and form of a subject by lighting it from different angles and carefully controlling the intensity of the various lights to reveal information about the subject.
Lighting an object only from the front tends to make it look flat and two-dimensional. It does little to give the subject definition and depth and bring out the features of the subject.
A video camera tends to accentuate shadows and sometimes they can make them look unnatural. A video camera also has the ability to zoom tightly on the subject and magnify the intensity of shadows. For those reasons, a lighting designer might choose to light a subject more flatly if video is involved.
But if we’re lighting primarily for an audience, then we can model the subject, illuminate its distinguishing characteristics, and make it look more natural from a distance.
Lighting can also create depth and give the appearance of space. By controlling the intensity of the foreground, mid-ground, and background, we can give the stage spatial reference and definition. This prevents objects and people from looking as if they’re on top of each other or right next to each other. We can also create depth by using backlight to highlight the form and shape of a subject.
Aesthetics and Mood
By using color, patterns, and projections, we can change the aesthetics and influence the mood of the audience (Figure 4). This is one of the areas where automated lighting excels. It can be bright and cheery, dark and moody, or simply paint a picture with an interesting aesthetic appeal.
Although any two people may or may not agree on what’s “aesthetically pleasing,” there are certain guiding principles. For example, the combination of blue and yellow creates a strong contrast. There are many other principles of colors and color combinations that are very useful as a starting point in lighting and scenic design.
Most lighting design is a combination of some or all of these objectives. The job of the lighting designer is to prioritize the goals of the project and make the best use of the tools to meet those objectives. In the end, the final result is often a compromise between what’s desired and what’s possible given the technology, expertise, creativity, and budget.
Once the design goals are decided, the task of laying out a lighting plot to meet those goals comes next. Any or all of these goals can be met using a three- or four-point lighting system.
A three-point lighting system uses three lights to illuminate each “acting area” on a stage. An acting area is a section of the stage, typically 8 to 10 square feet (2.5 to 3 square meters ) delineated by the lighting designer for the purpose of breaking down the task of lighting the stage into smaller areas with better control over the illuminance of a subject and the foreground, mid-ground, and background (Figure 5).
A lighting plot typically begins with a scale drawing of the stage and/or space in which the production will take place. By marking off a grid on the drawing of the stage, the designer can treat each of the acting areas to be lit as a single entity.
The three lights that light each acting area include the key light, fill light, and back light. The key light is the strongest light of the three and it represents the dominant source of light such as the sun or artificial light in a room.
In a three-point lighting system the key light is located 45 degrees above the horizon and 45 degrees to the left of the center line (as seen from the stage – Figure 6). The purpose of the key light is to provide visibility and to model the subject. The 45-degree angles provide enough shadow to help define the characteristics of the subject such as the nose, chin, and eye sockets.
The fill light is also located 45 degrees above the horizon and 45 degrees to the right of the center line. Its purpose is to help ameliorate the intensity of the shadows produced by the key light and control the contrast between light and dark. By adjusting the intensity of the fill light the depth of the shadows can be controlled and the amount of modeling can be adjusted.
The back light should be located directly behind the subject or acting area and it can be anywhere from 45 to 60 degrees or more above the horizon. The purpose of the back light is to bring out the shape of the subject and create depth.
If the luminaire/lens combination for each lighting position is carefully chosen and the plot is carefully constructed, then the peak illumination at the center of the beam will correspond with the center of each acting area, and the adjacent beams will overlap at 50 percent of the center beam intensity.
The point in the beam profile where the intensity is 50 percent of the peak is defined as the edge of the “beam” (Figure 7). The angle of the beam, therefore, is defined by the two points in the beam profile where the intensity is 50 percent of the peak. The beam angle is often given in the literature provided by the manufacturer or can be found in the specifications of the fixture online.
When two adjacent fixtures overlap at the edge of the beam, it should result in approximately the same illuminance where the two beams overlap as the center of a single beam because 2 x 50% = 100%. But it requires that the selection of lenses provides the right beam width at the throw distance chosen by the designer and meets the illuminance target of the design. After the key, fill, and back lights are selected and properly placed, the set can be duplicated for every acting area.
If the design is carried out properly, then at least three things will be accomplished:
- the light level anywhere on the stage will be high enough to create good visibility;
- the lighting across the entire stage from stage right to stage left and from downstage to upstage will be relatively uniform; and
- the lighting designer will have complete control over which acting areas can be lit or unlit.
The key lights and fill lights should be soft-edge fixtures like a Fresnel or a PC spot so that when they overlap with the adjacent key and fill light, respectively, they will blend well. The profile of a fixture is the cross-sectional plot of light intensity. When the profile is peaked and looks like half of a cosine wave form then the fixture has a “cosine beam profile.”
Two fixtures with a cosine beam profile will produce maximum uniformity when they overlap at the point in the beam profile where the intensity is 50 percent of the peak (Figure 8). A cosine beam profile is sometimes referred to as a blending distribution.
It’s important that there should be some means of controlling light spill to keep stray light off of set pieces, walls, the fascia of the stage, video display surfaces, the cyc, and any other surface that shouldn’t be lit by the stage wash. Some
automated lights have motorized barn doors or framing shutters that can be used for that purpose.
Toning a Three-Point Lighting System
In a three-point lighting system, the subject is typically lit with a warm/cool color contrast. The key light can be warm or cool light and the fill light should be the opposite of the key light.
The amount of color depends on the application. For a live audience the color contrast can be stronger, but video and I-mag strong contrast on opposite sides of a subject’s face can look peculiar.
If a production involves the use of video or film, a three-point lighting system may produce too much contrast between the light and dark areas. In those instances, a four-point or a multi-point lighting system, sometimes called a jewel lighting system, may produce better results.
In a four-point lighting system, the key light is moved directly in front of the subject and two fill lights are placed on either side of the subject. The back light remains in the same position as in the three-point lighting system.
Because the key light, which is a front light, projects directly onto the subject, it looks flat to the human eye, making it harder to distinguish features. But to the camera it looks more natural by de-emphasizing the shadows on the face.
In a concert touring system, the key light is typically provided by followspots. Many times there are at least two followspots for each band member, so the lighting is often a five-point system. If there are no followspots available, then the front light or key light is often provided by Fresnels, PAR cans, or Lekos, since they’re much more affordable compared to automated lighting.
The exceptions are when the cost of labor is very high, as in a convention space, or when time is very short.