Lighting Instruments


J. Michael Gillette. Theatrical Design and Production, 4th edition. Mountain View, CA: Mayfield Publishing Company. 1999. Chapter 14: Lighting Production

1. What is the difference between a floodlight and a spotlight?

A floodlight produces a large, almost uncontrollable wash of light; a spotlight, on the other hand, produces a small (8' to 12' diameter), highly controlled pool of light. Floodlights are generally used to light the backdrop while spotlights are used to light the actor.

2. Which units are spotlights?

  1. Ellipsoidal Reflector Spotlight
  2. Fresnel Lens Spotlight
  3. PARcan
  4. Automated Fixture
  5. Follow Spot

    and which are floodlights?

  1. Ellipsoidal Reflector Floodlight
  2. Border Light

Ellipsoidal Reflector Spotlight

Source 4- 26°
6" Ellipsoidal Reflector Spotlight
The six inch, Ellipsoidal Reflector Spotlight, often referred to as an Ellipsoidal, Leko (Pronounced: Lee-kO), ERS or Profile Spot, is the work horse of the commercial theatre. The instrument produces a hard edged, highly controlled pool of light. In academic and community theatres it is primarily found Front-Of-House in the Ceiling Cove, and on the Balcony Rail and Box Booms. Most commercial productions are lit almost entirely with the ETC Source 4 Ellipsoidal. The size of the pool of light is determined by the throw distance and which of the nine available lens chains the designer chooses. (Cost of an ETC Source 4 Ellipsoidal (50° to 19°) with a 575w lamp: $ 386 at StageTechnology)

ETC Source 4 Ellipsoidal Reflector Spotlight
at 40' throw
Factor (MF)
with 750w HPL
90° 75' 1.88 7 fc @ 40' throw
70° 56' 1.4 14 fc @ 40' throw
50° 38' .95 22 fc @ 40' throw
36° 25' .63 51 fc @ 40' throw
26° 18' .45 99 fc @ 40' throw
19° 13' .32 180 fc @ 40' throw
14° 10.4' .26 265 fc @ 40' throw
10° 8' .19 523 fc @ 40' throw
5' .12 854 fc @ 40' throw

Multiplication Factor = Diameter of pool / Throw distance
Diameter of pool = Throw distance * Multiplication Factor

3. What type of lens system is used in an Ellipsodal Reflector Spotlight?

Most Ellipsoidals use a lens chain composed of two plano-convex lenses arranged in a belly-to-belly configuration. Lenses are specified by their diameter and focal length. A 6x9 lens is 6 inches in diameter and has a 9 inch focal length.

4. What type of reflector?

An ellipsoidal shaped reflector. An ellipse has two focal points. The filament of the lamp is placed at one focal point and the shutters or gobo is placed near the second. The second focal point is also the focal point of the lens chain.

5. Which instrument, a 36° (6x9) or a 26° (6x12), should be used for a longer throw?

The 26° (6x12).

6. What range (wattage) of lamps are used in the 6" Ellipsoidal?

The traditional Ellipsoidal was designed for the 500, 750, and 1000 watt lamp. The ETC Source Four and Altman Shakespeare ellipsoidals use a new highly efficient 575 (or 750) watt lamp.

7. How large a pool of light would be produced by a 26° (6x12) Ellipsoidal with a 20' throw?

The diameter would be 9'.
There are three ways to determine the size of a pool of light--
  1. Graphically with a protractor, straight edge and scale,
  2. Mathematical: Size of pool = multiplication factor * throw distance, or with a
  3. Computer software program such as BeamWright, a small calculator program bundled with LightWright.
Using the mathematical approach: 20 foot throw * .45 multiplication factor (for a 26°) = 9.4 feet

Below is a simple JavaScript program which will calculate
Beam Diameter and Intensity for an ETC Source4 ERS.

Choose the Instrument, Enter the Throw Distance and Click the Calculate button.

Choose Instrument:

Enter Throw Distance: feet.

Beam diameter = feet.

Intensity = foot candles with a 750 watt HPL lamp.

Link to Sean Hennessy's BeamCalc, an online calculator similar to John McKernon's BeamWright.

8. How do you shape the pattern of light from an Ellipsoidal?

You can shape (actually frame or square-off) the pattern of light with the four shutters.

9. What is a "gobo" pattern?

A pattern (or template) which can be dropped into the "gate" of an Ellipsoidal creating a crude slide projector. A gobo can be used to project either a realistic image, such as a leaf pattern, or simply create a textured light.

9a. What is a Zoom Ellipsoidal?

A "Zoom Ellipsoidal" is an ellipsoidal reflector spotlight with a variable beam angle. There are two Source 4 Zooms-- one has a 15° to 30° beam angle and the other has a 25° to 50° beam angle. The obvious advantage of using a zoom ellipsoidal is that these two fixtures could replace four -- 19°, 26°, 36° and 50° -- traditional units. The major disadvantage is that the Zoom is more expensive ($570), heavier (17 lbs) and larger (23" long) than the conventional light.

10. In what mounting position are Ellipsoidals traditionally hung?

Front-of-house-- Balcony rail, Cove, Box Booms, FOH Pipe, Booth Pipe

Fresnel Lens Spotlight

6" Fresnel Lens Spotlight (Fresnel)
The 6 inch, 750 watt Fresnel (Pronounced fraa-nel, the 's' is silent) is a soft edged, variable beam instrument which is primarily used in the educational and community theatre. It is normally used on stage for area lights and general washes. The size of the pool of light is determined by the throw and the position of the focus knob: Spot to Flood. (Cost of an Altman 6" Fresnel with a 750w lamp: $ 158 at StageTechnology)

Altman 6" Fresnel Lens Spotlight
Focus Diameter at 20' Intensity with 750 watt lamp
Spot 6' (MF=.3) 230 fc @ 20' feet
Flood 28' (MF=1.4) 22 fc @ 20' feet

8" Fresnel Lens Spotlight (Fresnel)
The 8 inch, 1000 to 2000 watt Fresnel is a soft edged, variable beam lamp which provides a greater punch than its 6 inch brother. It is primarily used on stage for strong washes of side and back light or when the throw is too long for a 6 inch unit. The size of the pool of light is determined by the throw and the position of the focus knob: Spot to Flood. (Cost of an Altman 8" Fresnel with a 1000w lamp: $ 334 at Stage Technology)

Altman 8" Fresnel Lens Spotlight
Focus Diameter at 30' Intensity with 1000 watt lamp
Spot 6' (MF=.2) 189 fc @ 30' feet
Flood 25' (MF=.83) 22 fc @ 30' feet

The PARNel is an ETC Source4 PAR with a "patented wave lens system." It is a newly created fixture with the flexability of a 6" fresnel and the performance of a Source4 PAR. Like the fresnel, the PARNel has a soft edge and a variable (25° to 45°) beam angle. It is normally used on stage for area lights and general washes. The size of the pool of light is determined by the throw and the position of the focus knob: Spot to Flood. (Cost of an Source4 PARNel with a 575w lamp: $ 274 at StageTechnology)

ETC Source4 PARnel
Focus Diameter at 20' Intensity with 575 watt lamp
Spot 8.2' (MF=.41) 328 fc @ 20' feet
Flood 15.6' (MF=.78) 81 fc @ 20' feet

11. What is a Fresnel lens?

The Fresnel lens, developed in 1822 (for use in light houses) by Augustin Fresnel (1788-1827), is a less massive form of the more common plano-convex lens.

12. How does it differ from a plano-convex lens?

Augustin Fresnel reduced the mass of the plano-convex lens (B) by converting the convex side of the lens into a series of concentric prismatic rings (A). From the front, a Fresnel lens looks like a bulls-eye. For more information go to

13. What are the two commonly available sizes of theatrical Fresnels?

6 inch and 8 inch

14. What range of lamps (wattage) does each use?

6 inch: 500 and 750 watt.
8 inch: 1000, 1500, and 2000 watt.

15. What is the field angle of a 6" Fresnel at spot focus? At flood focus?

Spot focus: 16°
Flood focus: 70°.

16. How do you change a Fresnel from a spot to flood focus?

By sliding the focus knob from the back (spot position) of the light to the front (flood position) of the light.

17. How large a pool of light would be produced by a 6" Fresnel at spot focus with a 30' throw? At flood focus?

Spot: 9 feet.
Flood: 42 feet
Math for Spot Focus: 30 foot throw * .3 multiplication factor = 9 feet

18. How do you shape the pattern of light from a Fresnel?

The pattern of light from a Fresnel can be shaped with a barn door.

19. What device can be used to cut down the spill from a Fresnel?

The spill from a Fresnel can be reduced with a top hat or funnel.

20. In what mounting positions are Fresnels traditionally hung?

Fresnels are generally hung back stage behind the proscenium arch .


The PAR Can is designed as a holder and "top hat" for the 8 inch, 1000 watt PAR64 lamp. These rugged and efficient lamps, which gained popularity in the concert field, are typically used backstage for strong washes of down and back light. The size of the pool of light is determined by the throw and which of the four lamps the designer chooses. The VNSP (Very Narrow Spot) produces a strong visible shaft of light which can be used to simulate shafts of sun or moon light or create a Finger of God effect. (Cost of an Altman PARCan with a 1000w PAR64 lamp: $ 142 at StageTechnology)

Altman PARcan with 1000w PAR64 lamps
Lamp Beam Description Pool at 20' Intensity
FFN VNSP:Very Narrow Spot 3 1/2' x 8 1/2' 1000 fc
FFP NSP: Narrow Spot 5' x 9' 825 fc
FFR MFL: Medium Flood 7 1/2' x 16' 313 fc
FFS WFL: Wide Flood 12' x 18' 100 fc

21. What is a PAR lamp?

PAR stands for Parabolic Aluminized Reflector. It is a self contained, sealed-beam lamp which includes a parabolic reflector, a filament, and a lens.

22. What sizes (wattages) of PAR lamps are used in the theatre?

  1. 150 watt: PAR38. (Normally found in low budget community theatres.).
  2. 300 watt: PAR56.
  3. 500 watt: PAR56(Q) and PAR64.
  4. 1000 watt: PAR64(Q).
    (The PAR56(Q) and PAR64(Q) are tungsten-halogen (or "quartz") lamps.)

23. What is the shape of the pool of light from a PAR64?

The shape of both the PAR56 and PAR64 is oval. The long axis is approximately twice the length of the short axis.

24. What is the diameter of the "lens" of a PAR64?

8 inches. The diameter of the bulb of an American lamp is specified in 1/8s if an inch. A PAR38 is 4 3/4" in diameter, a PAR56 is 7" and a T20 has a tube shaped bulb which is 2 1/2 inches across.

25. What four beam angles are available in 1000w/PAR64 lamps?

  1. VNSP: Very Narrow Spot. (MF= .17 x .42)
  2. NSP: Narrow Spot. (MF= .25 x .45)
  3. MFL: Medium Flood. (MF= .375 x .8)
  4. WFL: Wide Flood. (MF= .6 x .9)

26. Which of these lamps do we use at JFAC? Why?

WFL: Wide Flood. Why? Because the Wide FLood will produce a pool large enough to cover the width (approximately 10 feet) between two on-stage electric pipes.

27. How large a pool of light would be produced by a PAR64/WFL with a 24' throw?

14' -5" x 21' -7".
Math: 24' throw * .6 multiplication factor = 14.4' = 14' -5" .
24' throw * .9 multiplication factor = 21.6' = 21' -7"

28. In what part of the entertainment industry are PARCans the primary light source?

The PARCan was first used in the 1970's to light the large scale Rock Concerts staged in hockey arenas.

29. Where, and how, are PARCans used in the theatre?

PARCans are normally used back stage to create strong washes of back and down light.

30. What is a StarPar or Source4 PAR?

Source 4 Par
Both Altman (StarPar) and ETC (Source 4 Par) have developed a 575 watt unit using a parabolic reflector to gather and focus the light. Like the PAR64, these instruments come with four interchangeable lenses -- VNSP (MF=.25), NSP (MF=.3), MFL (MF=.35x.5) and WFL (MF=.55x1). (Cost of an ETC Source 4 Par with a 575w lamp: $ 206 at StageTechnology)

    What is a PinSpot?

A PinSpot or RainLight is a PARCan with a built in transformer (120 volt to 6 volt) designed to hold a low voltage 4 1/2" PAR lamp. Typically it uses a 30 watt, 6 volt PAR36 VNSP with a 5° beam angle. This lamp produces a 2' diameter, 76 foot-cnadle pool of light with a 24' throw. (Cost of a PinSpot with a 30watt, 6 volt lamp: $ 20 at StageTechnology)

Automated Fixtures

31. What is an automated fixture?

An automated fixture -- also known as a moving light, intelligent light or "wiggle" light -- can be remotely focused (or refocused, colored, shaped...) from the control console.

32. What was the first "practical" moving light? When was it introduced?

Although Century Lighting (now part of Strand Lighting) included a "Remote Control Spotlight" in their 1960 catalogue, the first practical moving light, the Vari*Lite's VL1, was introduced by the English band: Gensis at their Abacab Concert in September 1981. Even though only 44 units were used at that first performance, the Vari*Lite soon became a standard feature in the light plots for the major touring artists of the '80 -- David Bowie, Linda Rondstadt, The Who, Diana Ross, Barry Manilow...

33. When did they move from the touring concert field to the theatre stage?

Eight years later (September 1989) English designer David Hersey introduced moving lights to the London West End when he used 19 Vari*Lites-- a combination of 9- VL2 (Spot) and 10- VL4 (Wash) fixtures -- on producer Cameron Mackintosh's Miss Saigon at the Theatre Royal Drury Lane. This production arrived at New York's Broadway Theatre in 1991.

Today most large Broadway musicals use automated fixtures. The Hairspray (August 2002) plot, for example, includes 496 conventional units (120 with Wybron Coloram II scrollers) and 56 moving lights from Martin Professional, Vari*Lite and High End Systems. Thirteen of these 56 units were hung front-of-house. Three on the Far FOH Truss, 6 on the Near FOH Truss, and 2 on each Near Box Boom.

34. What is the difference between a spot fixture and a wash fixture?

A spot fixture, such as the VL2 (or StudioSpot), generally includes a gobo wheel and produces a hard edged pool of light -- much like an ellipsoidal. A wash unit, such as a the VL4 (or StudioColor), produces a soft edged pool of light -- much like a PAR lamp or fresnel.

The StudioSpot is the hard-edged companion to the StudioColor® wash light. It projects a clean crisp image which will cut through a color wash. The unit features (1) 10 gobos (which are installed into the two gobo wheels), (2) 35 colors (through subtractive color mixing using two color wheels), (3) an 18º fixed beam angle lens system, (4) a variable speed iris, (5) mechanical-optical dimming and (6) precision focusing. With the normal 18º lens and a 30' throw, the StudioSpot produces a 270 foot candle, 9.5' pool of light .The unit weighs 59 lbs, uses a 575 watt (9000 lumen) discharge lamp and requires 24 DMX control channels plus a 110v power supply. (Cost of a StudioSpot (with lamp): $ 6,700 at Stage Technology)

Using the Cyan-Magenta-Yellow subtractive color mixing system, the High End System StudioColor 575 wash light provides the designer with (1) a virtually unlimited choice of colors, (2) mechanical-optical dimming, (3) an 8º to 22º selectable beam angle lens system and (4) precision focusing. The unit weighs 57 lbs, uses a 575 watt (9000 lumen) discharge lamp and requires 16 DMX control channels plus a 110v power supply. (Cost of a StudioColor 575: $ 6,000 at StageTechnology)

35. How are moving lights typically used in a theatrical production?

In the theatre, moving lights are typically used as refocusable and regellable specials. One automated fixture replacing perhaps as many as ten conventional lights. Designer Steven Haworth estimated that renting 8- StudioColor 575s saved him approximately 80 ellipsoidals, 60 circuits and 60 dimmers on his production of the Zion Passion Play. He used 4 Vari*Lite VL5s (a wash fixture) on a 1996 high school production of The Music Man saving him between 20 and 30 ellipsoidals plus related circuits and dimmers. Link to Haworth Associates web page on the Zion Passion Play

36. What are some of the problems associated with automated fixtures?

They are expensive (from 6 to 9,000 dollars, heavy, require a huge amount of time to program and need a console capable of handling a large number of control channels. For example, adding 6- StudioColor® 575s to our inventory would cost about $ 36,000, require an additional 98 control channels and another 342 pounds of counter-weight.

37. Are there less expensive alternatives to a Vari*Lite or StudioColor?


w/ ColorScroller
City Theatrical has developed the AutoYoke which will convert a conventional ETC Source4- 19º to 50º ellipsoidal into a moving light. City Theatrical accessories include the AutoIris and AutoFocus. The AutoYoke with a Source4 PARNel will create an inexpensive wash fixture. Seven DMX channels are need per light: 4 for the AutoYoke, 1 each for the AutoIris and AutoFocus and 1 for dimmer. The cost of the AutoYoke with a Source4 ellipsoidal, AutoIris and AutoFocus is about $3900. A color scroller will add an additional $600 (plus power supply) to the cost and an additional DMX channel to the hookup.

Rosco has developed the I-Cue Intelligent Mirror which allows the designer to focus (or refocus) the beam of light from a Source4 ellipsoidal from the control console. Only 4 DMX channels are required to position the mirror. The cost of the I-Cue is $745 (plus power supply).

All automated fixtures, including color scrollers, need a DMX feed from the lighting control console as well as a non-dim power feed to the lighting fixture or power supply.

Ellipsoidal Reflector Floodlight

Ellipsoidal Reflector Floodlight (or Scoop)
The 1000 watt, 16 inch Ellipsoidal Reflector Floodlight (or Scoop) is generally used to light the backdrop (or cyc) and/or provide a general wash of light over the entire stage. (Cost of an Altman 16" Scoop with a 1000w lamp: $ 317 at Stage Technology)
Altman 16 inch, Ellipsoidal Reflector Floodlight
with 1000 watt lamp
Throw distance 5' 20'
Pool diameter 10' 40'
Intensity 1120fc 70fc

38. What are the two commonly available sizes of theatrical Ellipsoidal Reflector Floodlights (or Scoops)?

Twelve and sixteen inch.

39. What wattage lamps are used in each?

  1. 12 inch: 500 watt
  2. 16 inch: 1000 watt

40. Where, and how, are Scoops traditionally used in the theatre?

Scoops are generally used to light the back drop (or cyc), provide a wash of down light over the entire stage or work lights for the load-in and load-out.

Border Lights

Border (or Strip) Light
Four to six sections of 6' (12 lamp) or 7 1/2' (15 lamp) Border (or Strip) Lights, using 120w or 300w R40 lamps, are generally used to light the backdrop (or cyc) and/or provide a general wash of light over the entire stage. (Cost of an Altman 6', 12 lamp, 3 circuit Striplight w/ 12- 300w R-40 lamps: $ 557 at StageTechnology)

Altman 6' Border Light with a 24 foot throw.
Size of "Pool" Intensity
300w R40/FL 31' x 24' 21fc / circuit
300w R40/SP 17.5' x 10' 73fc / circuit

41. What are the two standard lengths of a Border Strip?

Six foot, 12 lamp and eight foot, 16 lamp.

42. What type of lamps are used in Strip lights today?

Either Reflector lamps (such as the 120 or 300watt R-40FL) or PAR lamps.

43. How many circuits are in the traditional Border light?


44. How, and where, are Strip lights used in the theatre?

Like scoops, Strip lights are generally used to light the back drop (or cyc), provide a wash of down light over the entire stage or work light for the load-in and load-out. In 2009, I used 9- 1000w scoops (5 Blue & 4 White) to light the cyc from above and 3- 6' strip lights (White, Blue & Amber) to light it from below for Northern's production of Light in the Piazza.

Follow Spot

Follow Spot
The follow spot, a large, heavy, and expensive high intensity variable beam angle (zoom) spot light, is traditionally used to high light (spot) the lead performer, or performers, in a musical or dance production. The light should have an internal iris, a color-changer, a douser, and should be able to produce a sharp edged, head spot, from the back of the auditorium. Most musicals require a minimum of two lamps. (Cost of an Altman 1000Q FollowSpot with a 1000w lamp: $ 1547 at StageTechnology)

Altman Follow Spots
Altman 1000Q with 1000watt FEL lamp 64fc @ 80'
Altman Comet with 360watt FLE lamp 125fc @ 80'
Altman Satellite-1 with 575watt HMI (Metal Halide) lamp 375fc @ 80'
Each unit is set at the tightest beam angle.

45. What is the function of a Follow Spot?

Isolate the major performer (star) in a pool of light. There are two basic approaches to the use of a Follow Spot. In a Broadway Show the star (or stars) is usually spotted from the moment he makes his entrance to the moment he leaves the stage. In an academic or community production, the soloist is usually only spot lighted during the musical numbers.

46. What light source is used in the MainStage follow spot?

A 1000 watt "quartz" lamp, an FEL. Our unit is similar to the Altman 1000Q.

47. What internal devices are used to shape the light beam?

An iris and a chopper. The iris, which can change the size of the pool of light from a head spot to full body is used more frequently than the chopper.

48. How many colors are commonly held in the color boomerang?

Six. For a musical or ballet I would include (1) a "no color pink," (2) a "warm lavender," (3) a "very pale blue" and (4) a "light frost." The frost can be used to soft edge the pool of light, giving it a more subtle and less theatrical look.

49. How are these colors identified?

By their location, slot number, in the color boomerang. Both lamp and color are assigned numbers. A follow spot cue might sound like "Warning: Lamp 1 in color 2 on Dolly -- Go."

50. What is the minimum number of Follow Spots necessary to light a musical? Why

Two. Because the plot of a typical American musical is a love story, there will undoubtly be a duet ("Tonight") between the pair of young lovers (Tony and Maria in West Side Story).

50a. Where are the follow spots typically located?

In the rear of the balcony. For the past several musicals, we have located the follow spots (2 Source4 19° Ellipsoidals with a circle template) in the center of the ceiling Cove. This is a better position because it keeps the light off of the backdrop.

51. What are the standard warnings given to a new operator?

  1. Keep the light off the front of the stage.
  2. Keep the light off the act curtain.
  3. Learn to "sight" the lamp so you can "open" on the performer.
  4. Know where the edge of your beam falls.
  5. Don't let the performer slip out of the light.
  6. Include the entire body. Remember sometime they move unexpectedly.
  7. Don't let the beam get too big. The light should be a little larger than the performer.
  8. Don't jiggle.

Link to Instrument Selection Problem

Illustrations and photometric data are from the manufacturer's web pages.
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Revised: November 26, 2010
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