Lights

STAGE LIGHTING GUIDE

STAGE LIGHTING GUIDE

A GUIDE TO LIGHTING

Whatever the scale of a production - amateur or professional - lighting like other design processes is based on a sequence of logical decisions plus a good measure of creative inspiration.

This brief guide offers a sequence of step-by-step decisions to form the basis of a lighting process for the smaller scale production. It has been prepared by a lighting designer with experience of working on productions of all types and sizes. We hope that it will be especially helpful to amateur groups, small touring companies and educational theatre.


TYPES OF LIGHT
Floods
Soft Spots
Profile Spots
Beamlights
CHOOSING LIGHTING POSITIONS
Lighting from the front
Lighting from the back and side
Finding a compromise
DIVIDING THE STAGE
Dividing by area
Area planning for a play
Area planning for a musical
Colour planning for a play
Colour planning for a musical
THE DECISION PROCESS
Example plan for a play
Example plan for "In the round"
Example plan for a musical
DECIDING WHICH LIGHTS TO USE
THE RIG PLAN
LISTS
FOCUSING
Focussing in comfort
What can we adjust?
GLOSSARY

Types of Light

How do we choose which type to use in each position? As lighting equipment is so robust choice is further complicated, in that in addition to the range in today's catalogue, many earlier models are still in use. However lighting instruments group into families and it is convenient to consider our requirements in terms of what each family offers in terms of beam size, beam shape, and beam quality.

Floods

Floodlights are the simplest of all theatre luminaires, comprising of little more than a lamp and reflector in a box that can be panned from side to side and tilted up and down. As they have no lenses, the output characteristics of the floodlight are determined solely by the reflector and lamp type. The light is therefore suitable for lighting skies and cloths, it is not selective enough for lighting actors.

Floodlights are available in two variations - symmetric and asymmetric

Optical system of a modern symmetric stage floodlight

Traditional symmetrical theatre floods use 'domestic' shaped lamps in a bowl shaped reflector, giving a uniform distribution of light in all directions. Most modern theatre floodlights use linear quartz halogen lamps with a symmetrical half-pipe shaped reflector. The light is distributed equally above and below the horizontal axis of the lamp and, to a much lesser extent, equally to each side of the lamp.



Optical system of a modern asymmetric stage cyclorama light

Asymmetric floods, often called Cyc {Cyclorama} lights are a special type of the floodlight, used for illuminating back drops and scenery. They use a specially shaped asymmetric reflector in order to produce a light beam that spreads much further in one direction than the other relative to the horizontal axis of the lamp. This allows for a more even spread of light down the cyc cloth or back drop, or up the cloth if the cyc light is used as a groundrow. Like floodlights, there is also some light distributed to the sides of the lamp.


Floodlights may be single units, or grouped into 3s or 4s to produce a battern, used for colour mixing.

Focus Spots - Fresnels and PCs
Fresnel spots Profile and section of a fresnel lens from a stage spotlight

The fresnel (pronounced: 'fren-el') lens is unique in its design and is easily identified by the stepped concentric rings that form the surface of the lens.

The fresnel lens is named after its inventor Augustin Fresnel (1788-1827) who developed the lens for use in lighthouses to solve the problems presented by the basic plano-convex lens which was less efficient, too heavy and prone to cracking.

The fresnel lens has since become one of the most popular lenses used in luminaires for stage lighting, largely for the same reasons.


Optical system of a fresnel stage light

The fresnel luminaire is easily identified by looking at the lens from the outside of the luminaire where the concentric rings are easily seen.

Fresnel luminaires produce a soft edged beam of light that is brightest in the centre and gradually darkens toward the edges. This characteristic makes blending the light beams between adjacent fresnel luminaires into a continuous pool of light of even brightness quite easy.

The fresnel luminaire is the workhorse of all theatre luminaires. Fresnels are very versatile luminaires that are often used for stage colour washes, as well as for selective highlighting. The ease of blending the light beam from one fresnel with that of an adjacent fresnel makes them quick to point and focus onto the stage ready for use.



PC Spots Profile and section of a plano convex lens from a stage spotlight

Plano-Convex (PC) lenses are flat on the back (plano) and curve outward (convex) on the front.

The glass may be completely clear or the flat side may have a textured surface, the latter sometimes being called pebble-convex lenses. The textured surface softens the beam a little to improve the overall beam quality.

Older PC lenses tended to produce a rainbow around the edge of the light beam and project the filament outline in the centre of the light beam. Their glass was also prone to cracking. Modern PC lenses have largely eliminated these problems.


Optical system of a PC stage light

PC luminaires produce a light beam with a 'crisp' well defined edge with less light scatter than the softer edged fresnel luminaires.

The light beam characteristics of the PC spotlight make it ideal for dramatic highlights when focused to a narrow spot or for more general colour washes when focused as a wider flood.

Adding a light diffuser, such as Rosco 114 Hamburg Frost, changes the light beam to make it soft much like the light beam of a fresnel.

PC luminaires are ideal for use as tightly focused specials for highlights such as when you want to pick out a single performer for dramatic effect. They are also suitable for use in front of house positions.


Typical beam spread of a focus spot

Plano-Convex (PC) and Fresnel luminaires belong to the same family of "focus spots" with the only difference between the two being the type of lens that is fitted. Both types use a spherical reflector which, in conjunction with the single lens, provides a low cost optical system albeit a little less efficient than the more complex optical systems used in profile luminaires. The beam angle of focus spots is adjustable over a wide range, typically from a narrow spot of 4-10 degrees to a flood of 60-65 degrees. This adjustment is achieved by moving the lamp and reflector relative to the lens which is fixed in position on the body of the luminaire. Some models achieve this movement by means of a locking knob at the bottom of the luminaire that you loosen then slide back or forward while other models have a screw thread system with a knob at the back and/or front of the luminaire that is rotated to move move the lamp tray. Moving the lamp closer to the lens increases beam width towards its widest flood setting while moving it away from the lens reduces the beam width towards its narrowest spot setting.

An accessory called a barndoor is usually fitted to the front of focus spots to provide a means of controlling the edges of the beam.

Profile Spots
Fixed beam profile spots Optical system of a base down Fixed Beam Profile stage light

In a profile spot, the lamp and the reflector remain stationary while the lens is movable (whereas in the focus spot, the lens is stationary and it is the lamp and reflector that move). The lens movement in a profile spot controls the beam quality; the lenses are capable of producing a very hard precise edge which can be gradually softened by progressive movement of the lens tube. Control of beam size and shape in standard profile spots is achieved by adjustments at the central point of the optical system known as the gate. At this point, all profile spots have four shutters which can be used to make any size of four sided shape. There is a slot with runners which accept either an iris diaphragm to give a full range of circular beam sizes, or a metal mask to produce any required beam shape.

The profile spot is so called because it will project a profile of whatever two-dimentional shape is placed in the gate runners; and that profile can be projected to any required degree of hardness/softness by movement of the lens. A mask for use in the gate is known as a GOBO and because of the intense heat at this point in the lantern, gobos must be made from heat resistant material.

Moving the lens to adjust the edge quality also produces some variation in beam size, and so alternate adjustment of the shutters/iris and lens is often required to achieve the best performance from the spotlight. The development of subtle diffusers, such as Rosco 119 'Light Hamburg Frost', Rosco 132 'Quarter Hamburg Frost' and Rosco 140 'Subtle Hamburg Frost' allow lenses to be set for a hard edge and then softened with a filter. This is faster than softening with lenses, and makes more efficient use of the spotlights optics.

Most profile spots also have an adjustement allowing subtle changes to be made to the positioning of the lamp within the reflector. This allows the beam to be finely tuned between peak, where the centre of the beam is more intense, or flat where the beam has an even intensity.

The shuttering and masking devices in profile spots convert a lot of the unused light to heat and so shutters should be used to trim the beam edge rather than cut it down to size. This means selecting an instrument with the appropriate lens for the throw distance from the stage. Modern fixed beam profiles are available in beam angles such as :-

19deg - projected beam diameter will be approximately quarter of the throw distance
26deg - projected beam diameter will be approximately half the throw distance
36deg - projected beam diameter will be approximately equal to the throw distance
50deg - projected beam diameter will be approximately twice the throw distance
Zoom profile spots Optical system of an axial zoom Profile stage light

Zoom Profiles are profiles that utilise a precision optical system that comprises of an ellipsoidal reflector and two or more lenses to provide a light beam that can be focused to a soft or hard edge, zoomed from a wide flood to a narrow spot, and accurately shaped by framing shutters inserted into the gate. In a zoomspot two lenses are adjustable in relation to the lamp and to each other to enable the beam width and focus to be adjusted. The beam width is at its widest when the lenses are closest together and at its narrowest when they are at their furthest apart.

Fixed beam profile spots usually have only one lens, although some designs use two lenses, but in either case only the beam focus is adjustable and the lenses are optimised for the specified beam width.

To maximise their efficiency zoom profiles are designed to be used within a certain range of beam angles typical ranges are 25-50 degrees or 18-32 degrees.

Zoom Profiles vs Fixed Beam Profiles

Zoom profiles allow the size of the light beam to be readily set to the size needed for any particular purpose, minimising the light and energy wastage that may otherwise result from large shutter cuts. This also eliminates the need for lighting designers to calculate the exact beam angles required for each luminaire so the appropriate luminaires can be rigged for each show. The down-side is that the extra lenses and variable beam width makes zoom profiles a little less efficient. The wider the zoom range the less optimal the optical system becomes. This is why manufacturers make a series of zoom lens systems with limited zoom ranges rather than a single lens system that zooms all the way from pin spot to wide flood. When luminaires are routinely moved to different positions within a theatre, or toured to different theatres, the versatility of zoom profiles makes them the obvious and popular choice for multi-purpose venues and schools.

Fixed beam luminaires allow the manufacturer to optimise the optical system to achieve the best performance from the luminaire, at the specified beam width, to provide a more efficient luminaire with superior light beam characteristics that is simpler to use. When the luminaires are permanently rigged at the same positions in a theatre the need to calculate beam angles from one show to another is largely eliminated making it practical to select luminaires based more on efficiency and light quality than versatility.

Axial profile spots Optical system of an axial zoom Profile stage light Optical system of an axial zoom Profile stage light

Many of the latest profile spotlights use an axial mounted lamp rather than the traditional 'base down' design. Compact filament lamps such as the HPL575 used in conjunction with a coated glass reflector that can remove much of the infra-red energy from the beam, produces a highly efficient spotlight. These spotlights are often called 'coolbeam' spotlights and can provide the light output equal to a conventional 1000W spotlight using only a 600W lamp. The efficient heat management from the glass reflector, provides a cooler gate temperature, providing increased life to shutters, iris and gobos.

Beamlights and Parcans

Most lighting instruments produce a conical beam so that the spread widens as the throw increases. Beamlights use a parabolic reflector to produce a near parallel beam which is more intense than a lens spotlight of the same wattage.

In the parcan the optics are fully contained within the glass envelope of the lamp. Various Lamps providing angles of a squashed near-parallel beam are available. The intensity produces a depth-enhancing haze in the air, so intense that it is effective even with deep colours. The basis of most rock lighting today.

LED Technologies

The lighting families that we have already discussed (floods, focus spots, profile spots and beamlights) have assumed the use of traditional incandescent lamps as the source of illumination. Recent developments in LED {Light Emitting Diode} technology, have permitted these devices to be bright enough to be used as lighting sources.

LED lights used for stage lighting all fall into the same families as their traditional incandescent counterparts, the only signigicant difference been changes to the light source and reflector design.


CHOOSING
LIGHTING
POSITIONS

Lighting from the front

Consider the effect of a light starting as a vertical downlight on an actor then moving in a frontal plane until its beam becomes horizontal and then carries on to light from below. How visible will be the actor's face, particularly eyes and teeth? To what extent will face and body be modelled or flattened? Whatarea of stage will be selected and what will be the size and direction of shadows cast on floor and scenery?

Actor lit from above spotlight hung vertically

A vertical beam is the most selective light possible. The lit area of stage, and the shadow cast upon it, need be no wider than the widest part of the actor. However, the actor's eyes will be black pools and a highlighted nose will shade the mouth.

Actor lit from above spotlight angled 30 degrees to the front

If the light comes from a little forward of the actor, it will start to reach the eyes and mouth (provided that she keeps her chin up and is not defeated by a hat brim!). However, the lit area, and shadow cast, starts to extend upstage from the actor - i.e. the light is slightly less selective

Actor lit from above spotlight angled 45 degrees to the front

As the lighting comes increasingly from the front, the actor's eyes and teeth receive more light. But the area lit extends further and further upstage, reducing the selectivity and increasing the likelihood of the actor's shadow hitting the scenery

Actor lit from above spotlight angled 90 degrees to the front

As the light becomes more and more frontal, the actor's features become flattened (and so also does three dimensional scenery). The lit area and the actor's shadows increase until, when the light is horizontal, there is a lit corridor for the entire depth of the stage, and the actor shadows become actor length.

Actor lit from above spotlight angled 120 degrees to the front

Light from below projects an actor shadow that looms above the actor rising and falling as she moves towards and away from the light source. When this is the only lighting angle, the effect on the face is not at all natural. But a little from below, usually just reflected light can help to soften the harshness of light from above.

Lighting from the back and side

Now consider a light from behind. Then a light or lights from a series of side angles (i.e. lights at right angles to those considered above). Once again the criteria is visibility, modelling, selectivity and shadows.

Actor lit from behind spotlight angled 30 degrees to the rear

A light source behind the actor does not illuminate the face, but it helps to give depth to the stage by separating the action from the scenery through creating a haze and highlighting head and shoulders. The shadow of the actor is cast forward, helping the selection of areas. Since the light does not fall on the face, strong colours can be used.


Actor lit from one side only spotlight angled 30 degrees to the left

If the light comes from a little to one side of the actor it will start to reach the eyes and mouth on that side. The area lit, and the shadows cast, will extend along the stage floor on the other side.

Actor lit from both sides spotlights angled 30 degrees

Add a second light source from the other side, and both sides of the face will receive light. However, there is now a second shadow and the selected area of stage floor extends to both sides of the actor.

Actor lit from both sides spotlights angled 45 degrees

As the side lighting comes from an increasingly lower angle, the shadows will lengthen to both sides of the actor and a larger corridor will be selected across the stage. As the light hits the

face from a lower angle, it will light more into the eyes and teeth, although there will still be a tendency towards a central dark line where the beams meet down the centre of the face.

Actor lit from both sides spotlights angled 90 degrees

As the angle lowers, sidelight has an increasingly modelling effect on the actor's face and body. This is particularly important in dance. When the light becomes horizontal there will be a lighting corridor across the whole stage. By focusing just clear of the floor, it is possible to lose shadows into the wings, and the light will only be apparent when an actor stands in it.

Finding a compromise

We normally seek to light an actor for maximum visibility and maximum modelling, with minimum shadow. Additionally in many productions, we need to select as tight an area as possible. Which combination of angles offers the optimum compromise?

Actor lit by a pair of crossed spotlights from the front angled at 30 degrees

The basic compromise that has long been the standard approach is a pair of beams crossing on to the actor (one for each side of the face) from positions that are both forward and to the side of the actor. The suggested angle is often around 45 degrees in both directions - i.e. midway between

vertical and horizontal and midway between front and side. However to restrict the shadows cast and to give a better 'join', the lights are often positioned closer to the vertical and to the centre.

Actor lit by a three crossed spotlights providing front and rear illumination

A backlight added to the basic crossed pair brings depth to the scene and generally enhances the 'look' of the actor. The backlight can be used for strong atmospheric colour if required, while the crossed pair maintain a more natural tint on the actor's skin tones. Note: The actor is now It by three beams with a 120 separation between them.

Actor lit by single spotlight can by very selective

The problem with 'crossed pair' lighting (with or without a backlight) is the extent of the spread of light on floor and scenery beyond the area where the actor's head is lit (remember that head is usually about five feet above the floor). Although a single beam can be flat it can also be quite tight.


Actor with back lighting to reduce flatness

Adding a backlight can enhance this flatness quite considerably - and the selectivity is still a tightly controlled upstage/downstage corridor without side spillage.

Actor lit by four spotlights for modeling

For modelling, sidelights can be added and, although they will spread the lit area, they can be at quite steep angles since they do not need to make a major contribution to visibility. Note: Four beams now light the actor with a 90 separation between them

SPECIALS

The major proportion of a stage lighting rig is focused to form a palette of areas and colours whose various combinations will provide the desired fluidity of selectivity and atmosphere. However there are certain lights whose function is so 'special' that they cannot make a significant contribution when mixing the basic palette.

For the Actor

Specials usually consist of spotlights set so tightly that the spaces they light cannot be considered as areas. They are often for moments when an actor has to be picked' out (perhaps only head and shoulders) on an otherwise blacked-out stage. They need to be listed in a priority order for close scrutiny and reduction to essentials.

For Special Effects

There may be a request for equipment to produce clouds, flames, water, lightning, etc. When listing it is always prudent to remember that such effects can draw attention away from the actor rather than positively support a performance. And if the effect is essential, then the effect of light reflected from fire or water is often more telling than a pictorial representation of the actual fire or water.

For the Scenery

The proportion of the rig focused on the scenery will be very small. With the exception of skies and back or front cloths, scenery normally gets sufficient general wash from the reflected light bouncing off the stage floor from the lights that have been set for the actors. Indeed, as discussed in the following pages, many of the basic problems of lighting design arise from difficulties in stopping actor light hitting directly on the scenery Successful lighting of scenery depends on augmenting the diffuse reflected general light by selective highlighting of chosen scenic elements, or parts of these elements. This can vary from bold gashes to soft emphasis. Again, to be listed and reduced to essentials after a debate based on priorities and available resources..


DIVIDING THE STAGE

Dividing by Area

Once decisions have been made about the kind of contribution that we expect lighting to make to the production that we are planning - and these contributions have been put into some sort of order of priority - we need to break down the stage area into the segments over which we require independent selective control. The required breakdown may be symmetrical, in which case the stage plan will be divided into something that resembles a series of areas of different sizes corresponding to the placing of the action. Of course it could well be that there is no need for division into what it is useful to call production areas: all the stage may be in use all the time. In this case a simple division into centre and sides will allow balancing for maximum 'enhancement' of the look of the scene. Note: Adjoining areas overlap - both side to side and back to front. And remember to remember that these are areas where an actor's head is to be lit - they ore unlikely to be the some as the light patterns on the floor

Area planning for a play

In this naturalistic play -possibly but not necessarily in a box set -the areas are determined to a considerable extent by the positions of furniture and doors. And the lighting is expected to make some logic in terms of practical light fittings (table lamps, wall brackets, etc.) and the natural sunshine and moonlight coming through windows (including those in the audience's 'fourth wall'). In this particular example, we have a play where it is desirable to focus attention at various times on the sofa, the armchair, the table (with that essential tool of modern drama, a telephone) and the doors. These doors are tremendously important in any drama: some of the key appearances and speeches are made there. But for a long intimate scene on the sofa, it is useful to concentrate on that sofa and loose peripheral areas like the doors. Consider the seven areas shown here in terms of possible combinations: the area palette gives the director a wide range of selectivity of audience vision - whether a subconscious fluidity (slow cues that are not obvious) or an area selection obviously linked to the switching of the practical lamps

Area planning for a musical Musicals tend to have many scenes and many selective and atmospheric light changes within these scenes. Therefore, unless there are many - very many - lights available, the breakdown into areas has to be very general. In this example the breakdown is symmetrical because, as in so many musical productions, the settings consist of a symmetrical series of wings leading to a backcloth, possibly a skycloth. With the addition of cloths and scenic pieces, the method of staging gives a flexible masked acting area with the possibility of sufficient open space for dancing and lots of entrances for a large chorus to get on and off quickly In most musicals the big moments are staged in the downstage areas: to help both musical balance and the 'putting across' of numbers to the audience. For the same reasons, much of the essential action takes place centre stage. The most common selective lighting cue is to 'concentrate centre', usually downstage centre, by 'losing the edges'. This suggests a minimum of three areas across the stage - certainly at the front of the stage, and probably also midstage. However, it is often quite practical to consider the whole width of the rear of the stage as one area. This provides a seven area combination that offers an area palette giving the director considerable selectivity with the possibility of progressive tightening from back to front and from sides to middle.

Colour planning for a play

In a naturalistic play, colour is often used to create a fluid atmosphere that can shift from warm cheerfulness to cool sadness. If an area is lit with some lights in warm tones and some in cools, the dimmers of the control board can be used to achieve a whole series of options from an extreme of the warm colour alone, through the neutrality of both together, to the other extreme of cool colour alone. Which (if any) of the areas need to have this kind of 'double cover' of colour tones? In this example, discussion with the director has established that such a colour palette seems necessary around the central areas and the desk, whereas the upstage corners and downstage right can manage on a warm tint only - although perhaps one that is a little closer to a compromise neutral than the warms in the mixable areas. In such a naturalistic production the actual colour tints chosen are likely to be quite subtle.


Colour planning for a musical

The dialogue scenes of a musical require the subtle colour tones that are appropriate for a naturalistic play However, the musical numbers, particularly when solo singers can be given isolating visibility from tightly focused follow spots, usually call for strongly atmospheric colouring. And many dance sequences, where the body is relatively more expressive than the face,

respond well to positive use of quite strong colour This example shows a much used technique where the colour is applied in rather broader washes than the areas selected for scene location. The front half of the stage is divided into three areas, each lit from above in rather saturated colours: a hot and cold rather than a warm and cool. The rear half is treated as one area, also with a hot and cold from above. From the side comes further washes, probably in slightly less saturated hues. These may divide the stage into bands: in this case an upstage band and a downstage band, possibly splitting the stage into left and right but just as likely covering the full width. With relatively neutral colour from the front, saturated colours from above and intermediate colours from the side, we have a colour palette that offers considerable scope.


THE DECISION PROCESS

So how does one decide where to put the spotlights? On many stages and in many auditoria there is not much choice: but, to make the best use of the positions available, it is necessary to start from an ideal and compromise that ideal to fit reality. By WHERE, we mean where to put the light and where to point it. Traditional advice involves a lot of crossing of light beams - partly to help model/sculpture the actor by introducing a partially side-light angle and partly because lighting diagonally across a stage provides a bigger spread of light from each lamp: an important bonus when equipment is in short supply. Crossing the beams opens out the area lit but can cast excessive shadows on side wall or masking. And so, with spotlights becoming increasingly versatile as to beam width, there is every reason to consider using the traditionally discredited method of lighting the actor with light coming straight in from the front. Of course if this is the only light, yes it will be flat. (And if the available positions are so low that an actor shadow will be thrown on to the sky, then better to come diagonally - priorities again!) But with the addition of some backlight (even if it is nearly vertical) and some sidelight, the front-lit actors will come alive and the areas/ shadows brought more under control. There need not be precise side lighting for every area: it can often be quite general since it is frequently more important in the big wide areas than in smaller tighter areas (more important, that is, in priority terms!). In the examples shown here, the traditional crossing method has been used for the play, while the actors in the musical are lit' flat frontal'. But it could be vice versa. Whichever way, the next stage in the planning is to establish where the lights go and where they point.

Example plan for a play

For each area of our play we need two lights. One for each side of the actors' faces. When an area requires a full colour control of cool and warm, the number will double to four spots - a crossed pair in warm and a pair in cool. A spot bar immediately behind the proscenium arch will give a suitable angle for lighting the upstage areas, but for the downstage areas a position in the auditorium is necessary Red and blue have been used to indicate warm and cool filters in the spots. Green indicates more neutral washes that have been added from back and sides. Not enough equipment? Well, do we really need all these areas? And so many of them with both warm and cool? (Back to priorities?)

Or rather than a pair, we could use a single straight in - but if so, we must make it really straight in because a single crossing beam does not do much for the other side of the face!

Example plan for "In the Round"

For staging in the round, light needs to come from all sides. And it should be evenly balanced to avoid favouring one segment of audience to an extent that is not really permissible in a staging form so democratic as theatre-in-the-round. To avoid hitting into audience eyes, light has to come from both within the acting area and from outside it. Angles can be closer to the vertical than in other forms of staging because the audience is closer to the actors and thus visibility is 'easier'. Example plan for a musical

In this musical the actors' visibility light is provided by spots in a neutral colour hitting straight in. The front areas are covered from the auditorium, the midstage areas from a bar just inside the proscenium, and the upstage areas from a midstage bar If the stage is very wide, two or more lamps may be required for each area as indicated. Strong colour comes from near vertical backlights and medium colour from the wings (on stands, booms or ladder-frames to be discussed under 'rigging).

Note: For clarity these plans only include actor lights. The play would require light outside the window and on the door backings, while the musical is likely to need a colour mix for the backcloth and possibly specials for elements of scene.


DECIDING WHICH LIGHTS TO USE

Deciding which instrument to use obviously depends to a large extent on what is available - meaning another exercise in listing priorities. For 'FOH' (front of house) throws of any distance in the auditorium, profiles are essential, both to avoid undesirable lighting up of the auditorium from scatter light, and to allow sufficiently precise control of the beam to prevent spillage on to the proscenium. However in a small hall there is a lot of merit in considering fresnels or PCs (well barndoored) at close range when a lot of spread is possible from a few lamps. For onstage use, Fresnels and PCs come into their own with fast-to-set soft edges - profiles are the most versatile instruments but they inevitably take longer to focus. For backlight, fresnels and beamlights are favourite, while floods are to be thought of only for wide expanses of scenery. (Use for actor light only in situations of extreme desperation). For theatre-in-the-round, barndoored fresnels give the required smoothness and spread. Existing installations in most theatres and halls are likely to be based on fresnels and profiles: anyone buying new equipment should look seriously at including a goodly proportion of the new generation PCs giving smooth soft-edge beams without stray scatter light and at the versatility of the variable beam profiles.

This plan shows instruments being allocated to our play in a very orthodox way: profiles for the front-of-house and fresnels for onstage. If a couple of PCs were available, they would be a useful alternative on the ends of the stage spot bar: this is a position where any scatter light shows up badly on the side walls of the set. Whether 500 or 1000W units are required will depend mainly on length of throw, perhaps with the changeover around 6 to 8 metres. However, it is important always to remember that the actual level of light intensity is not so important as the BALANCE.

Fresnels have been allocated everywhere because they have a good smooth spread (profile edges can be very difficult in small theatres in the round). Every spot must have a barndoor to contain spill from the audience eyes. Each become a pair of spots since this is the only way that it is possible to light fully to the sides of the acting area. Too many-spots? Then perhaps just one cover in a neutral shade (thereby halving the number on the plan) and utilising a couple of pairs of straight downlighters to add colour toning in warm or cool.

The actor face lights are profiles from the front and fresnels onstage, with the second bar being less powerful units - face light is rarely important upstage in a musical. The backlights are fresnels, although parcans would be nice if available. For the sidelighting, profiles have been used downstage to contain the light in a tight corridor across the front - often advisable when front cloths or running tabs are in use. Midstage sidelighting use fresnels for a good spread, while the optional upstage sidelight again uses profiles to keep the light clear of the skycloth.


THE RIG PLAN

THE PLAN is the kernel of any lighting design. It shows, at minimum:

  1. The POSITION of each light.
  2. The TYPE of light in each position.
  3. Any ACCESSORIES, such as barndoors or gobo, required by any particular light.
  4. The DIMMER that will control each light.

An example of a Rig Plan

The plan should be drawn to scale (1" to 1 ' or 1:25). This helps accurate indication of light positions. And if scale symbols are used for these lights, there is a check on space problems: if it can be drawn on the plan, there will be room for it on the stage. Any shapes may be used to indicate lights, but plans are more easily read if the symbol resembles the outline shape of the light. Either way, the plan should certainly include a key showing the type of lighting instrument represented by each symbol. Colour and dimmer are indicated by number: the usual convention is to write the colour number inside the symbol and the dimmer number alongside the symbol. Lights fixed to horizontal bars are easy to show in plan: the bar can be drawn in the position that it will occupy over the stage and its height indicated by a note (such as + 14') written at the end of the bar. Lights fixed to vertical bars, or stacked on a series of brackets, are more difficult to draw - they must be indicated diagrammatically FOH lights in the auditorium are usually drawn much closer to the stage than their scaled real distance which would make the plan inconveniently large. The easiest method is to work on tracing paper over a ground plan of the scenery and stage.

A good procedure is:

  1. Establish all lighting positions with Xs
  2. Convert these Xs to symbols of available (and/or acquirable) lighting instrument types, drawing them pointing in the approximate direction of proposed light travel.
  3. Write colour numbers inside symbols.
  4. Add dimmer numbers alongside symbols.
  5. Trace through key features of the set and stage - it is usually possible to trace through (in spaces clear of lighting drawing) enough to relate the positions of lights to the geography of the setting and stage.

This will bring the plan to a point where it can be used to prepare and rig the equipment. The lighting designer's own copy will grow many extra markings to indicate precisely where the lights are to be pointed - markings so detailed that they would only confuse if included on all copies of the plan.

LISTS

From the plan, lists are prepared of the required number of:

  1. Types of Light
  2. Length of cable.
  3. Accessories.
  4. Colour Filters.
  5. Section Drawings.

Section through stage showing the masking of lights by the borders

Will there be borders to mask the lights (and other things) hanging above the stage? If so, draw a section to check that all the light beams will be able to reach all desired parts of the actors and the scenery. Usually (but not always) the heights of the borders and lighting bars can be adjusted. Only a section will determine what these relative heights should be, and only a section will determine how effective the masking arrangements will be for an audience eye in the front row.


FOCUSING

Focusing is probably the most important part of the whole lighting operation. Not even the most sophisticated marvel of a microprocessor control desk can fill in that dark spot where the lights have not been properly overlapped. Nor can a hard edge be softened or a disturbing spill on to a border be shuttered off. Focusing involves tricky ladder work so that there is every incentive to get it right first time - although, inevitably, it will be necessary to get at the odd spotlight between rehearsals for a little fine adjustment.

Focussing in comfort

If you stand with your back to the light that you are focusing, (1) You will avoid being blinded (2) You will be able to see what the actor's light is doing to the scenery

Focusing with back to the light (A)

No clear shadow of head, therefore head is not lit.

Clear shadow of head, therefore head is lit

Focusing with back to the light (B)

Focusing with back to the light (C)

If the lighting designer is shorter than the actor, make an allowance - check by raising hand

What can we adjust?
ON ALL LIGHTS

Left/Right & Up/Down

ON SOFT SPOTS

Bigger/Smaller

with optional Barndoor rough shaping (& control of spill)

ON PROFILE SPOTS
Round size by optional iris

Shape size by shutters

Texture by optional GOBO

Beam edge quality by lens differential movement of two lenses

Shape by shutters

The most difficult types of light are the basic Profile Spots since there is an interaction between shutters (or iris) and lens movement. Although adjusting the lens is principally a means of making the edge of the beam harder or softer, it will also change the size. Therefore it is usually necessary to adjust shutters and lens alternately to get the desired combination of size and edge quality

Most profiles have an adjustment whereby the light can be adjusted so that it is either smooth across the whole spread of the beam, or 'peaked' to be brighter in the middle with the amount of light falling off towards the edge. For most purposes it is easier to light with an even brightness across the beam and so it is recommended that anyone beginning to work with light should use an even beam until through experience they discover a need for a 'peaky' beam.

SOFT SPOT
Controls on a Fresnel spot
VARAIBLE ANGLE PROFILE SPOT
Controls on a zoom profile spot
FIXED ANGLE PROFILE SPOT
Controls on a fixed beam profile spot

GLOSSARY

Backlight
Light coming from behind scenery or actors to sculpt and separate them from their background.
Bar
Horizontal metal tube of scaffolding diameter for hanging lights (pipe in America)
Barndoor
Four-shutter rotatable device which slides into the front runners of fresnel and PC focus spots to shape the beam and reduce stray scatter light.
Battens
Lengths of overhead lighting floods arranged in 3 or 4 circuits for colour mixing.
Beam angle
Angle of the cone of light produced by a spotlight.
Beamlight
Lensless spotlight with parabolic reflector giving intense parallel beam
Board
Contraction of switchboard or dimmerboard. The central control point for the stage lighting.
Boom
Vertical pole, usually of scaffolding diameter, for mounting spotlights.
Boom arm
Bracket for fixing spotlights to a boom.
Build
An increase in light intensity.
Channel
A control circuit, identified by number, from the 'board' to a light.
Channel access
The method (levers, pushes, keyboard, etc) in a memory system by which individual channels are brought under operator control.
Check
Decrease in light intensity.
Colour call
A listing of all the colour filters required in each lighting instrument.
Colour temperature
A method of measuring (in Kelvin units) the spectral content of 'white' light.
Control Surface
Any device such as lever, push, wheel, rocker, mouse, pen, cursor, etc, used as an interface between an operator's fingers and a processing system which activates dimmers or motors controlling lighting instruments.
Cross-fade
Lighting change where some of the channels increase in intensity while other channels decrease.
Cue
The signal that initiates a change of any kind. Lighting cue is a change involving light intensity alterations.
Cyclorama
Plain cloth extending around and above the stage to give a feeling of infinite space. Term is often rather loosely used for any blue skycloth, either straight or with a limited curve at the ends.
Dead
1) The plotted height of a piece of suspended scenery or bar of lights.
2) Discarded items of scenery.
Dichroic
Colour filters which work by reflecting unwanted parts of the spectrum rather than absorbing them in the manner of traditional filters.
Diffuser
A filter, often called a frost, which softens a light beam, particularly its edge.
Dimmer
Device which controls the amount of electricity passed to a light and therefore the intensity of that light's brightness.
Directional diffuser
A filter which not only softens the beam but spreads it along a chosen axis. Also known as a silk
Director
Has the ultimate responsibility for the interpretation of the script through control of the actors and supporting production team.
Discharge lamps
Special high powered light sources whose use is normally restricted to follow spots and projection because of difficulties in remote dimming by electrical means. includes C.S.I., C.I.D. and H.M.I lamps.
Downstage
The part of the stage nearest to the audience.
Ellipsoidal
Strictly a type of reflector used in many profile spots but extended in North America to cover all profile spots.
Flood
Simple instrument giving fixedspread of light.
Flys
Area above the stage into which scenery can be lifted out of sight of the audience.
Focusing
Strictly speaking, theadjustment of lights to give a clearly defined image; but usually used to cover the whole process of adjusting the direction and beam of spotlights in which the desired image may be anything but clearly defined.
FOH
All instruments which are 'front of house', i.e. on the audience side of the proscenium.
Follow spot
Spotlight with which an operator follows actors around the stage.
Fresnel spot
Spotlight with soft edges due to fresnel lens which has a stepped moulding on the front and a textured surface on the back.
Frost
A diffuser filter used to soften a light beam.
FUF
Full-up-finish. An increase to bright light over the last couple of bars of a musical number.
Gate
The optical centre of a profile spot where the shutters are positioned and where an iris or gobo can be inserted.
Gauze
Fabric which becomes transparent or solid under appropriate lighting conditions.
Gobo
A mask placed in the gate of a profile spotlight for simple outline projection. Also used, with softened focus, to texture the beam.
Groundrow
A low piece of scenery standing on the stage floor. Also lengths of lighting placed on the stage floor.
Group
A subdivision, temporary or permanent, of the channels in a control system.
Hook clamp
A clamp for fixing an instrument to a horizontal bar, usually of scaffolding diameter.
Houselights
The decorative lighting in the auditorium.
Instrument
A stage lighting unit, such as a spotlight or flood. An American term coming into increasing international use.
Iris
An adjustable circular diaphragm to alter the gate size in a profile spot. Also the muscleoperated diaphragm in the human eye which adjusts the eye's aperture to changing light intensities.

Kilowatt
see wattage
Ladder
Framework in the shape of a ladder for hanging side lighting.
Lamps
The light source within an instrument, but sometimes used as an alternative to the word instrument.
Lantern
A lighting unit designed or adapted for stage use. A traditional word now being overtaken by 'instrument'.
Linear flood
A flood using a long thin double-ended halogen lamp, allowing the reflector to be designed for an increased beam spread.
Load
The lights controlled by an individual dimmer and limited by the rating of that dimmer.
Master
A lever or push which overrides (or 'masters') a complete preset, or group within a preset or selected memory.
Memory
Lighting control systems where channel intensities for each cue are filed automatically in an electronic store.
Multiplexing
Passing control instructions, particularly to dimmers or remotely focusable lights, by sending all information in digital format along a single pair of screened wires.
Pan
Horizontal (left/right) movement of an instrument.
Parcan
The simple instrument which holds a par lamp and therefore does not require any optical system of lenses or reflectors.
Par Lamp
A sealed beam lamp with the filament contained within the same glass envelope as an optical system producing a near parallel beam.
Patching
A sort of central 'telephone exchange' where channels can be connected to dimmers and/or dimmers connected to socket outlets.
PC [Plano Convex] Spotlight
A lens with one flat surface and one curved surface. This 'PC' lens and the fresnel lens are the alternatives normally used in stage spotlights.
Pipe ends
Spotlights on the ends of lighting bars, crosslighting to model dancer's bodies.
Playback
The part of a memory system where memorised lighting states are recalled to control the light on stage via master levers or pushes.
Practical
Light fitting which is not merely decorative but is wired to light up.
Preset
Anything which is positioned in advance of its being required --such as props placed on the stage before the performance. A control system where each channel has more than one lever to allow intensity levels to be set (i.e. preset) in advance of a cue.
Profile Spot
A spotlight which projects the outline (i.e. the profile) of any chosen shape and with any desired degree of hardness/softness.
Profiled Cue
Lighting change where the rates of increasing and decreasing intensities accelerate or decelerate during the progress of the change.
Rating
The maximum and minimum power in kilowatts that can be controlled by a circuit or dimmer channel.
Record
Plotting a cue state by filing it in the electronic data storage of a memory board.
Resistance dimmer
An older mechanical form of dimmer which reduces the flow of electricity to a light by progressively converting the surplus into heat.
Rigger's control
A remote portable hand-held control unit which allows channels or groups to be switched from the stage for focusing when the control room is unmanned.
Scatter
Low intensity light cast outside the main beam of an instrument.
Scrollers
Colour changer where a roll of filters are taped together and positioned by a very fast motor activated by digital signals from a control system which includes a memory facility.
Shin Busters
Low level lights at stage floor level, used mainly for dance.
Sightlines
Lines drawn on plan and section to indicate limits of audience vision from extreme seats, including side seats, front and back rows, and seats in galleries.
Silks
Diffusion filters which stretch the light in a chosen direction.
Spigot
An adapter screwed to the hanging bolt of an instrument to enable it to be mounted on a floor stand.
Spill
Stray or scatter light outside the main beam.
Spotlight
An instrument giving control of the angle of the emerging light beam and therefore of the size of area lit.
Strobe
Device giving a fast series of very short light flashes under which action appears to be frozen.
Theatre-in-the-Round
A form of staging where the audience totally encircle the acting area.
Throw
Distance between a light and the actor or object being lit.
Thrust
Form of stage which projects into the auditorium so that the audience are seated on at least two sides.
Tilt
Vertical (up/down) movement of an instrument.
Tungsten lamps
Older type of lamps (the stage types are high wattage versions of standard domestic lamps) whose tungsten filaments gradually lose the brightness of their light output.
Tungsten halogen lamps
Newer lamps (now virtually standard in professional theatre) which maintain their initial brightness of light output throughout life.
Upstage
The part of the stage furthest from the audience.
UV
Ultra violet light (from which harmful radiation have been filtered out) used to light specially treated materials which fluoresce in an otherwise blackened stage.
Variable bean profile
Profile spotlight using a type of zoom (q.v.) arrangement where the differential movement of two lens allows wide variations in both beam size and quality.
Wattage
The power of consumption of a lamp, or the maximum available power from a dimmer. A kilowatt is 1,000 watts.
Ways
The number of channels in a control system.
Zoom
A differential movement of two lenses in an optical system. In a simple zoom, the lenses are moved independently, but in more complex forms a single movement alters the size of the beam while the image remains in constant focus. Used in advanced profile spots and scene projectors.

Download the handbook to the stage lighting guide

Download the original Stage Lighting Guide as a printable Acrobat PDF file.

Download the original Stage Lighting Guide as a printable Acrobat PDF file.


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Revised and updated - April 2017