Stage lighting is not an exact science. Rules are few, if indeed there are any. Provided that the lighting works with the other elements in the production to enable author and actors to communicate with their audience, virtually anything goes. But even when that going is done by a particularly extreme anything, the resultant lighting will usually be a specific combination of certain possible roles that light can play in a production.
What can lighting contribute to a production? What are our aims when we employ light on the stage?
Communication between actor and audience depends on sound and sight. Actors’ complete bodies, but especially eyes and mouth, are their means of communication and must be clearly visible if a character is to be projected. Everything in theatre interacts and light is closely related to sound: actors who are difficult to see will usually be difficult to hear.
So the first basic requirement of stage lighting is sufficient illumination to achieve positive visibility. But how bright is that? Light is a measurable quantity but photometric measurements have little place on the stage: one of the indications of the approach of theatrical doomsday will be the appearance of a lighting designer with a photometer.
Theatre is much too much of an interplay of mind and matter to be reduced to precise physical measurements. We must have confidence in the judgments of our senses: if it looks right then it is right.
Unless the auditorium is very small, perhaps up to about ten rows, the amount of light cannot be ideal for all seats. If there is enough light for the front row, there will be insufficient for the back; if the amount is correct for the back row, it will be over-bright at the front.
This assumes that all members of the audience have identical eyesight: which they certainly do not! The amount of light required will vary with the brightness that has gone before.
The human eye contains a mechanism, the iris, to adjust eye sensitivity to varying light conditions. This iris mechanism is not immediate in response and so the amount of light needed when the curtain goes up will vary with the brightness of the auditorium lights that have just gone out: the stronger the houselighting, then the stronger must be the opening stage lighting.
An overture played with the houselights low or out and some light to dress the curtain —or dress the stage if there is no curtain —gives an opportunity not only to prepare audience sound sensitivity but to adjust their light responses to the scale of the production’s audio-visual palette.
Once the performance gets under way, the required quantity of light remains related to what has gone before. A change from relative brightness to relative darkness must take into account the time-scale of the change.
A dark night scene which the audience have been watching for several minutes may be quite visible, but plunge them into such a night from a bright sunny scene and they will require a positive measure of time to readjust —and in that time, communication may be lost and the magic theatrical spell broken.
Within each stage picture, the amount of light is also relative. If one actor is brighter than another, it must be for a dramatic purpose. The 7-foot tenor in the chorus who always gets his head in the light becomes the unfortunate brightness reference point for the whole stage.
The usual solution is not an increase of the overall stage intensity to match the bright point, but a reduction of this over-bright part to balance with the rest of the stage.
In a two-actor scene, it is often better to balance by reducing A rather than by increasing B.
Balance is the key to the amount of light required; brightness is relative rather than absolute.If the balance is good, plotting the lighting from a mid-point in the auditorium will ensure an acceptable level for both front and back rows; but the wise lighting designer will use dress rehearsals to try seats in all parts of the house. Light quantity is only the very beginning of the stage lighting story.
In a conventional proscenium theatre where the audience sit in a block facing a picture-framed stage, there is a tendency for the stage picture to appear rather flat with only two dominant dimensions (width and height).
The third dimension (depth) is, of course, present but less obvious. This tendency towards apparent flatness increases as the size of the auditorium increases and a larger proportion of the audience is seated further away from the stage.
Indeed this is a major reason for enthusiasm for alternative theatre forms where the stage thrusts into the audience or even, as in theatre-in-the-round, becomes surrounded by the audience.
Director, designer and actor use many techniques to stress the third dimension and restore apparent depth to the production. The spacing of scenic pieces relative to one another and the use of exaggerated perspective are fundamental design techniques.
Directors, often using several levels, group the actors to emphasise stage depth. But lighting designers can kill all such effort with one tiny wave of their magic wand. By pumping light flat onto the stage from the front —particularly from a low, near horizontal, angle —the stage picture can be given an appearance of total flatness. Under flat lighting, actors’ noses will not stick out and their eyes will not recede; dancers’ limbs will pirouette in squashed ovals rather than true circles. But, with sympathetically angled light, actors can be presented as natural three-dimensional humans rather than as the pasteboard cut-out figures which can be the inevitable product of proscenium staging. So we must strive for a sculpturally lit actor.
If the lighting is flat, there is little point in designing sculptural scenery. Scenic wings receiving equal frontal light will appear to run together, solid chunks will appear flat and lumps of physical texturing will just not be visible. Solidity only becomes apparent when contrasts of light and shade are created by directional lighting. So we must strive for a sculpturally lit scene.
But a sculpturally modelled actor in a sculpturally modelled environment is not the end of the dimensional story. There can still be a tendency for such an actor to merge with the background. By use of light, partly from the sides but especially from the back, it is possible to enhance the illusion of depth in this relationship of actor to background. It is a technique much used in the television studio where lighting makes a major contribution to restoring picture depth within the two-dimensional screen.
The use of backlight streaming over actors’ shoulders may be difficult to justify on smaller stages where there is a shortage of equipment for the more basic requirements. Nevertheless, one chunky back lighting instrument can make all the difference to the illusion of stage depth.