Lighting Plot Symbols

Why This Matters

Lighting plots are the universal language of theatrical lighting—they're how your design moves from imagination to reality. When you hand a plot to an electrician, master electrician, or touring crew, those symbols communicate exactly what fixtures go where, how they're circuited, and what they're meant to do. You're being tested not just on recognizing symbols, but on understanding why specific fixtures serve specific purposes: beam quality, control capabilities, and practical applications.

The key to mastering lighting plot symbols is thinking in categories: conventional versus intelligent fixtures, hard-edged versus soft-edged light, and fixture versus accessory versus documentation. Don't just memorize what each symbol looks like—know what lighting problem each fixture solves and when you'd choose one over another. That conceptual understanding is what separates a designer from someone who just hangs lights.

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Hard-Edged Fixtures

These fixtures produce crisp, defined beams that can be shaped, shuttered, and focused to precise edges. The key mechanism is a gate (or aperture) at the focal point of the optical system, which allows for sharp pattern projection and beam shaping.

Ellipsoidal Reflector Spotlight (ERS)

• Symbol: elongated hexagon or "football" shape—the most common fixture symbol you'll encounter on plots, often with a line indicating barrel length
• Produces sharp, controllable beams with four shutters for precise shaping—ideal for isolating performers or architectural elements
• Accepts gobos and templates at the gate, making it the go-to fixture for texture, pattern projection, and specials

Followspot

• Symbol: similar to ERS but often with an operator notation—indicates manual operation from a designated position
• Tracks moving performers with adjustable iris, color boomerang, and intensity control—essential for soloists and star entrances
• Requires a trained operator and dedicated sight lines, so plot placement must account for throw distance and angle

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Soft-Edged Fixtures

Soft-edged fixtures create diffused, blendable light without harsh boundaries. The optical design—whether a stepped Fresnel lens or a simple reflector—scatters light rays to eliminate defined edges.

Fresnel

• Symbol: circle with a small rectangle (lens housing) attached—represents the distinctive stepped-lens design
• Produces soft, blendable light with adjustable spot-to-flood focus via a sliding lamp-and-reflector assembly
• Ideal for backlight and side wash where you need coverage without visible beam edges—the workhorse of area lighting

PAR (Parabolic Aluminized Reflector)

• Symbol: circle with parallel lines indicating beam orientation—lines show the oval beam's long axis direction
• Delivers punchy, intense output from a sealed-beam lamp with fixed focus—originally borrowed from aircraft landing lights
• Beam shape is oval, not round, controlled by rotating the lamp within the housing; available in various spreads (CP60, CP61, CP62)

Strip Light

• Symbol: long rectangle with multiple cells indicated—represents the linear array of lamps or LEDs
• Provides broad, even washes across wide areas—typically used for cyc lighting, border positions, or footlights
• Individual cells can be circuited separately for color mixing when using primary gel colors (R, G, B, or R, G, B, A)

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Intelligent and Moving Fixtures

These fixtures contain onboard motors and electronics for remote control of multiple parameters. DMX protocol allows the console to control pan, tilt, color, gobo, and intensity—all from a single data cable.

Moving Light

• Symbol: circle with crosshairs or directional indicators—often includes a notation for fixture type (spot vs. wash)
• Offers pan, tilt, color, gobo, and effects from a single unit—replaces dozens of conventional fixtures in flexible designs
• Requires careful plotting of home position and range of motion—ensure no physical obstructions limit pan/tilt travel

LED Fixture

• Symbol: varies by manufacturer but often includes "LED" notation—may use traditional fixture shapes with added identifier
• Color mixing via additive RGB, RGBA, or RGBW arrays—no gel changes needed, infinite color palette from one fixture
• Low heat output and energy efficiency make them ideal for positions near performers, scenery, or heat-sensitive materials

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Specialty Fixtures and Positions

These fixtures serve specific scenic or atmospheric purposes beyond general illumination. Their plot symbols often reflect their unique mounting or function.

Cyclorama Light

• Symbol: asymmetric reflector shape or dedicated cyc notation—indicates the specialized throw pattern for even backdrop coverage
• Asymmetric reflector design throws light across tall cyc surfaces from close mounting positions without hot spots
• Typically deployed in groundrow and overhead positions to create seamless top-to-bottom color washes on backdrops

Practical

• Symbol: often a unique icon or "PRAC" notation—represents any visible, onstage light source
• Part of the scenic design, including table lamps, chandeliers, candles, or neon signs—must appear realistic to the audience
• Usually dimmed separately and may require special circuiting for prop handling and actor safety

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Accessories and Modifiers

These aren't fixtures themselves but modify how light behaves. Plot symbols for accessories typically appear within or adjacent to the fixture symbol they modify.

Gobo

• Symbol: "G" or gobo number notation within the fixture symbol—indicates a pattern template at the gate
• Projects patterns, textures, or images by blocking portions of the light beam—breakups, windows, leaves, abstract shapes
• Steel gobos for simple patterns; glass gobos for detailed images—rotation and indexing possible in intelligent fixtures

Color Scroller

• Symbol: "S" or scroller notation attached to fixture—indicates a motorized color-changing device
• Holds a string of gel colors that scroll past the lens opening on command—typically 16-32 colors per string
• Adds color flexibility to conventional fixtures without the expense of intelligent lights—ideal for repertory or touring

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Control and Documentation Symbols

These symbols don't represent fixtures but provide essential information for installation and programming. Accurate documentation prevents costly errors during load-in and tech.

Dimmer

• Controls intensity by varying voltage to conventional fixtures—essential for fades, cues, and atmospheric shifts
• Plotted as a number or notation associated with each fixture, indicating which dimmer rack channel powers it
• Modern systems use digital dimming protocols, but the concept remains: one dimmer controls one or more fixtures at matched intensity

Circuit Number

• Identifies the physical electrical path from dimmer to fixture—critical for troubleshooting and load balancing
• Appears as a number near the fixture symbol on the plot, often in a distinct location from channel numbers
• Must match the actual cable runs installed in the venue—errors here mean fixtures that won't light

Channel Number

• The control address assigned in the lighting console—what you call up when programming cues
• Appears prominently on the plot, often circled or boxed for quick reference during focus and programming
• Allows grouping of multiple fixtures under one channel for unified control, or individual addressing for precise manipulation

Focus Point

• Notation indicating where the fixture aims—may be a letter, number, or area designation on the plot
• Critical for the focus call when electricians adjust each fixture to hit its intended target
• Documented in focus charts that accompany the plot, ensuring consistent recreation of the design

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Quick Reference Table

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Self-Check Questions

1. Which two fixtures both produce hard-edged beams but differ in their ability to track movement? What makes each appropriate for different staging situations?

2. A designer needs soft, blendable light for an acting area wash. Compare the Fresnel and PAR—which offers more flexibility in beam adjustment, and why might you still choose the other?

3. You're reading a plot and see both a circuit number and a channel number for the same fixture. Explain what each represents and why both are necessary for a successful load-in.

4. Compare how a gobo and a color scroller modify light output. If an FRQ asks you to create texture and atmosphere in a forest scene, which would you specify and why?

5. An LED fixture and a conventional PAR with a color scroller can both produce multiple colors. What are two advantages of the LED approach, and when might the PAR/scroller combination still be preferred?