Lighting considerations for the bathroom

Bathroom lighting is an integral part of the home lighting considerations. Unless you live in a studio flat, where the bath and shower unit are then subsumed within the living area, then the demands on lighting the separate bathroom will require some additional thought.

The first point to note is that bathroom lighting requires a mixture of ambient lighting and spot lighting. You need a certain level of ambient lighting to brighten the whole area, unless you are the sort that prefers to have a shower in the dark, surrounded by candles, every time you use the bathroom! You just need a small amount of general lighting so that you are able to see what you do. It is a good idea to use lights that do not require much electricity, so that the running costs are minimised. Some people simply have a ceiling light running on a energy saving bulb, and find that it suffices for them. Energy saving bulbs, however, take a bit of time to warm up to produce the required wattage of light, and if you were merely doing a quick visit to the bathroom you might find you might even exit it before the light is sufficiently bright, when it is still in the firing up process. For some people, however, they find this minor inconvenience negated by the fact that the running costs will be lower compared to a normal bulb.

You also need a bit of spot lighting in certain areas, particularly around the mirror. Why? It is so that when you are getting ready in the morning, you can see your face clearly in the mirror as the light falls on it to brighten it up. The light around the mirror should be of higher intensity than the ambient lighting provided by the ceiling light, so that the image in the mirror is more visible compared to the background. It is likely that without the mirror lights, your reflection in the mirror would be darker, because the light from the ceiling light would cast your shadow into the mirror.

Ideally, the mirror lights should be either above or to the side of the mirror, and angled slightly towards the middle, so the reflected light off the subject is diverted across to the other side of the face. If the mirror light is directly in front then it was cause direct glare; it is similar to watching a concert performance and having a backlight shoot right into your vision.

It is unavoidable that the mirror light be sites in close proximity to the user so it might also be a good idea to use translucent fixtures around the lamp so that the direct glare is cushioned.

If your bathroom is larger enough and you have certain decorative objects you wish to emphasise – or perhaps it is the bath itself – you may wish to focus some spotlights on these points of focus. These should be small focussed lights with higher lumens.

Bathroom lighting follows the same principles as other areas of the house. Consider the general lighting demands in addition to task specific lighting, and highlight points of interest. Consider also the light levels increased by reflective surfaces and glare as a result of siting. Selecting the fixtures for these may depend on the running costs. But if you get the balance right, your bathroom will be the perfect blend of function and design.

Lighting for the theatre: spot, flood and fresnel lighting

Lighting is used in the theatre and the stage lighting can really make a significant impact on not just the effectiveness of the scene, but in the production in general. There are many types of lighting and they vary according to the function within the scene.

Spot lighting is a way of focusing the audience’s attention on a character or object. We often see spot lighting used to bring out the characters in a scene, you will notice that they are bathed in brighter lights than the background, or perhaps in larger scenes, those who have parts will be spot lighted while the others work in general illuminance.

But you do not necessarily spot light the actors who have speaking parts in the scene. You spot light those who have impact on the scene. For example, if a group of characters are investigating a crime and are examining the evidence, while behind them the responsible criminal is slinking away, the latter will also be spot lit as he withdraws. If some people are hunting for an object hidden in the background, the object gets subtly spot-lit too.

Flood lighting is another kind of lighting seen in the theatre. As the name itself suggests, the lighting is used to illuminate a wide area strongly. If a scene requires characters to be simultaneously brought out, such as if they are in group conversation, flood lighting is used. But if one of these characters leaves the group and walks to a corner of the stage, then he is picked out by spot lighting which follows him around until he returns to the group.

How can lighting influence our views subtly? Imagine this scene on stage. A man is leaving the family home against the wishes of the elders. If we use a spotlight of lower intensity on him, and flood light the rest of his family, we influence the audience into thinking the decision is wrong. But if we spot light him in higher illumination, it makes him out to be heroic, brave and influences the audience to support him.

What happens if you want to illuminate a large area but without the brilliance? That is to say, you want to softly illuminate a large area. If that is the case, you use what is known as Fresnel lighting. Fresnel lighting covers a wide area, but in soft focus. For this reason Fresnel lighting is always used as a background lighting method, for general purposes.

In the previous example scene, the man would be spot lighted, the family flood lighted, while we could use Fresnel lighting for the background.

Lighting can communicate to the audience on a subtler level. It can move together with or against the stage. If a protagonist claims he will act for a just cause, but the lighting on him is lower than the general lighting, leaving him less illuminated, then any faith we have in his abilities is challenged.

Lighting can make a significant impact on screen. The next time you are at a theatre, analyse the scene, and how the lighting is used to convey meaning and intention subtly. It will help you become a better lighting engineer.

Wireless Controlled Lighting Systems: a sign of the times?

In the last post we looked at sensor lighting for homes, where the lighting is controlled by timing devices which come on or off automatically. The limitation with sensor or timer-related devices is the accurate of the delay or the sensor. For example, if you are deep in concentration at a task, you don’t want the lights to go off because they cannot sense you are in the room.

Imagine you were trying to repair a laptop or something requiring your focussed attention. At the most inopportune moment you’re left hiding a screwdriver in one hand, a pair of pliers in another, while trying to wiggle one leg in the hope of triggering a sensor.

Another lighting feature that is growing in importance is wireless controlled lighting. In this form of lighting, the lighting is controlled via wireless means, so you could adjust the lighting from a smartphone. As most people are often glued to the phone or have it close by, to the point that it is described as their third hand, or a leash, using this as a lighting control is not unnatural, it is a seamless extension of the device.

The primary push behind this sort of thinking – controlling lighting wirelessly – is undoubtedly lifestyle. In the modern age, turning on lights from a wall socket is seen as outdated and backward. In fact, many new build homes now come with wirelessly controlled lighting as the norm. Young first time buyers, all of whom will have grown up with a smart phone in their teenage years view this as a sign of status. The use of wirelessly controlled lighting may make a positive impression of a property and its asking price. Some home owners install it prior to sales, upgrading their old lighting systems, because the increase in the asking price a property could fetch would outweigh the lighting cost.

But wirelessly controlled isn’t just growing on the younger generation. Older citizens are installing it too, to save on the physical effort to adjust lighting, especially if they have mobility difficulties. Having to brighten or dim the lighting without having to get up may be a benefit to some.

There are other advantages too. If you are leaving on a long holiday but in your haste to get away you forgot to turn off a set of lights, those lights are going to announce to the world, especially those who see them lit continuously, that your property is vacant and ripe for a break-in. If you had wireless lighting you could turn them down on your journey. And while you are away, too, you could turn the lights on and on to give the impression of occupancy. Wireless lighting is a boon for security, not just a status symbol! Of course, it means you have to choose a really good password, as you won’t want someone else running your household controls for you.

Wireless lighting can be preset to adjustable levels, such as with the brightness on your television screen. It is a quick efficient way to adjust lighting controls without adjusting individual lights, and can bring about valuable time-saving.

Bill Gates has a remote controlled house where he could call in on the way home for it to prepare his bath, or to get the kettle boiling to prepare a cup of tea. Will the average house be like that? Probably not in the immediate future, but perhaps wireless technology will make its impact elsewhere. For now though, it seems that wireless controlled lighting systems will become more commonplace in the future and every household may eventually adopt one.

Sensor lighting systems and their limitations

A simple lighting system in the past consisted of an overhead lamp turned on and off by a wall switch. Nowadays you could easily into a room and find no switches at all. How do you turn on the light? Actually, by the time you consider that question, you may find that the light has already come on for you. And when you leave, the light will automatically go off a little while after you exit the room.

Increasingly sensors are being used as the primary trigger for lighting devices. These sensors were originally for security purposes, such as to trigger an intruder light in the porch, or to start a recording device. But as with all technological things, the lifespan of such things is lengthened when more uses are found for them, so it is no surprise that these systems, which consist of a motion detector, an electronic control unit, and a controllable switch (relay), have made their way into interior lighting.

How do these light sensors work? A motion detector detects movement, and sends a appropriate signal to the control unit to close the circuit, which would allow light to come on. If there is no activity after a period of time, the circuit is opened again until movement is detected.

The detection of an occupant in the initial entry to trigger the lighting easy, it is similar to entering the field of view of a PIR detector. But how do detectors know when a person has left the room, or is sitting still in the settee?

Imagine if someone has entered the room to read, fallen on the settee, and woken up in complete darkness!

Another problem that current sensor lighting systems cannot solve is that if the delay between the circuit reset is too long, then if you are entering a room for only ten seconds to retrieve an item, then light and energy are wasted while the circuit remains closed before it resets again.

The current technology is being enhanced in all areas, including cost reduction by maximising the efficiency and lifespan of parts, as well as the increased capability to detect occupancy by means other than movement, so that if you are still for a while, the unit is aware of your presence despite your lack of movement.

Some current products being trialled include heat sensing technology, but it may be awhile before improvements in technology lower the cost to a level acceptable enough to be implemented in household units. But even then, these heat sensing units may not even address the problem. What if you are ready to fall asleep and the unit refuses to let you turn the light off? Another kind of sensor being trialled is one that gradually lowers the lighting level in the room if it senses no movement. But it would require the use of dimmable bulbs, instead of energy saving ones.

Sensor controlled lighting was implemented so that lights would not be left on overnight and waste electricity. But there are still improvements to be made. But perhaps it may be fair to say that instead of relying on automation, everyone should just make the effort to make sure energy is not wasted. It appears that the more advanced the technology is, the more it has been designed to make us stop taking responsibility for ourselves.

Managing lighting in your later years

As we grew older, the back of our eyes receive less light. Furthermore, the size of the pupils decrease with age, and to compound the problem, inside your eyes, the lenses become thicker and absorb more light. The result is that we find it harder to see and often have to strain. If that were not enough of a problem, the lens in each eye also scatters the light, which adds a little veil of light over images on your retina. How does this affect us?

Firstly, it makes it harder for us to perceive contrast. This means that if we are reading newspapers, the difference between text and background is diminished with age. The sharpness of objects is a second way in which we are affected. Objects lose their distinctness, and we find it difficult to focus on them. Thirdly, the distinction between certain colours becomes reduced. Reds start to look like pinks, and the distinction between blues becomes minimised.

But all is not lost! There are changes in lighting you can do to manage the problems that come with age.

Firstly, choose lighting of higher lumens. Since the eyes receive less light, you have to increase the background lighting levels to the general areas. Choose light bulbs with high lumens so that areas are brightened. Remember to distribute light throughout a room so that darker areas within a room are minimised.

Secondly, remember to consider the glare levels. If you are increasing overall levels of light, the glare factor will also increase. Remember to avoid direct glare and reflection of the light from shiny surfaces into your eyes.

Thirdly, if you do a lot of reading, put extra light where you read, so that you can read without tiring your eyes or causing discomfort. Install more task lights around the house. A task light is a light for a specific task – for example, a desk lamp to help with reading, or extra cabinet lighting to help you search for what you need. It is a good idea to install task lights on the opposite side of your master hand. If you are right-handed, for example, place a desk lamp on the left side, so that there are no shadows that fall exactly where you need more light.

Your vision is affected as you grow older. But that doesn’t mean you need to accept the deterioration as the norm. With clever management of lighting, you can adapt your surroundings to maintain your quality of life.

How to design lighting for interiors

Lighting can really make a difference to the way a room is presented. If you looked at the way a room is presented on one of the property shows on television, you will see that the best ones are almost always lit when the prospective buyers enter the house. Or if you glanced at an estate agents sales brochure or website, the properties that are advertised always use lighting to their advantage. I’ve known a few couples to be slightly disappointed when they visit properties because they’ve seen for themselves that the property they thought looked light in the sales brochure or website did not really materialise in its actual state. And one individual even decided not to sell, after seeing how his own property could look like with a bit of clever interior lighting in the estate agents’ sales brochure!

Getting interior lighting right requires consideration, but it is not beyond the lay person, unless you have really specific requirements for what you want to achieve. Otherwise it is a simple matter of considering these few easy steps.

Consider the focal points of the room first. The focal points of the room are the ones you want people to notice. They can be structural or decorative. A structural focal point is one that is part of the building itself. Perhaps it is the low beams you want to emphasise. Perhaps it is the fireplace. Or it could be a specific historical feature that has been carefully preserved. These are all structural focal points. A decorative focal point is a piece of furniture or art, an internal decoration, that draws interest. It could be a nice Ming vase, or a framed picture. Whether the focal points are structural or decorative, bring them out from the other areas of the room.

How can you bring them out? The point to remember is that the local lighting to these areas has to be higher than the general lighting. You have to get more light focussed on the areas. Direct lighting may be suitable in some cases, especially if the reflected object or surface is dark or non-reflective. But if there is the likelihood of glare, then consider diffusing the light around these features, or using small focal lights to emphasise them.

After the features of the room have been considered, the next thing you want to do is consider the specific functions for the activities in the room. Perhaps you have a writing desk in a corner. You’ll need to put some focussed local light there, but be sure to consider the impact it has on other areas of the room. If you have a wall-mounted television, decrease the amount of lighting around the area to minimise glare.

After focal points and functional uses have been considered, the last thing to consider is the lighting for general ambient purposes. How much light do you need for general usage of the room? It goes without saying that the general ambient lighting should not exceed the specific local lighting in the other areas, otherwise you end up with a room that is extra bright, or one where the specific lighting has no significant impact.

The fixtures you use for various lighting purposes vary. For focal points, a very general rule might be to used diffused lighting to minimise glare. For purposes such as writing, or perhaps small focal points, use direct focussed light but be mindful of reflective glare. The needs for ambient lighting can vary according to the time of day and the seasons as well, so it may be worth considering fixtures with dimmer switches so the surrounding lighting is within control and more manageable and adaptable to the needs.

Using the correct interior lighting doesn’t require a lot of mental agony. Just consider the layout of the room, what you want to emphasise and what your needs for the room are. Then plan the lighting with these in mind. And your interiors will look a million dollars, without costing that much!

Light properties, and why it is important to know them

Light is a complex medium with which to work. While light itself is understood by science, how it is perceived by humans is still not fully comprehended. Different people react to light in different ways, and it is important to be sensitive to what people like and dislike with certain properties of light.

Light travels in straight lines, and so it is easy to predict where light will fall within a room. Standard mathematics can be used to determine if a light source will be visible and have a high glare, or if light will fall on a particular surface. When light travels through different materials, such as air and glass, then the direction of the light will change. Most of the time this is not relevant, but when lighting glass it is important to remember the principle of total internal reflection. If the light contacts the glass at a very shallow angle, almost parallel with the surface of the glass, then it will not penetrate it, but reflect off it and away, similar to a mirror. This is important to note, since in some cases it will not be possible to light through a piece of glass, such as a step, if the light is being transmitted next to it.

Light properties are usually discussed in terms of the following:

Luminous Intensity
Luminous intensity is the measure of visible light in a particular direction per solid angle. The SI unit for luminous intensity is the candela (cd). This gives a good indication of the intensity of the light emitted from a lamp. Most lamps with a beam angle (generally up to 60°) will have a peak intensity, or candela, value. This allows comparison between different lamps with a beam angle and gives an idea of the maximum light output.

Luminous Flux
Luminous flux is the measure of the visible light output of a light source (a lamp). The SI unit for luminous flux is the lumen (lm). Whereas luminous intensity deals with visible light emitted in a particular angle, luminous flux is the light emitted all around a light source. The lumen value is generally given for unidirectional lamps, such as fluorescent tubes and standard incandescent lamps. This is another way of comparing the light output between different lamps to see which is brighter.

Illuminance is the measure of luminous flux per unit area. The SI unit for illuminance is lux (lx). One lux is equal to one lumen per square metre. In most homes an illuminance level of between 100lx and 500lx is required, depending on the different areas in the home. A house would not be lit with 500lx through its entirety, as this may only need to be achieved on some work surfaces. Most residential lighting designs do not need or want measured illuminance levels, but it may be helpful to compare different lamps and the actual light output. Most lamp manufacturers produce a light cone, which shows the peak illuminance at different distances. These provide a quick comparison of the actual light output from a lamp, and show which is brighter.

Power in lighting refers to the electrical power used by the lamps in the system. The SI unit of power is the watt (W). Almost all equipment will have a maximum wattage that it can control. Some will have a minimum wattage as well. It is important that these limits are observed, since if they are exceeded then it could mean early failure of either the light fittings or the equipment. For example, many dimmer switches have a maximum wattage of 250W. If the lighting circuit carries more than 250W, for example three 100W incandescent lamps, then this could cause the dimmer to overheat. It is normally acceptable to have less than the maximum wattage on lighting equipment, unless it is a fluorescent or metal halide lamp, in which case it must be matched. Efficacy Efficacy is similar to efficiency, but is the ratio between two figures with different units. In lighting terms, efficacy relates to the lumen to watt ratio. This is a common way of measuring how low energy a light source is. It is the number of lumens emitted divided by the number of watts of power consumed, and is noted with the unit lm/W. There are different variations of the lm/W ratio. Some take into account the power losses of transformers and ballasts used by a light fitting (commonly noted as a circuit watt), and some also take into account the light lost when a lamp is fitted into a light fitting (the luminaire lumen value as opposed to the lamp lumen value).

Electric Potential
Electric potential is measured in Volts (V). An electrical circuit will have a voltage associated with it. In most cases this matches the national voltage, provided by electric companies to homes. In the United Kingdom this is 230V AC, whereas the United States uses 120V AC. There are variations across the world, so if light fittings are being purchased from other countries, it is important to ensure that they will work in the installation.

Current is the flow of electric charge. The SI unit of current is the amp (A). There is a maximum amount of current that can be taken into a home, and this in turn limits what can be used for lighting. There is a maximum amount of power that a dimmer switch can handle, which is related directly to the maximum amount of current that can flow through that dimmer switch. Current, Voltage and Power are all inherently related to one another, and if two values are known then the third can be calculated using the formula Power = Voltage x Current. In some cases, such as with on/off switches, there will not be a maximum wattage but rather a maximum current, commonly 10A. It is worth being aware of the different values required and how to find them out.

LEDs generally require a constant current to make them emit the maximum possible light. Rather than a specified voltage, like most other lamps have, many LEDs have a specified current, such as 350mA or 700mA. It is important to obtain an LED driver that matches this to enable them to work at maximum efficiency, and avoid damaging the LEDs.

Correlated Colour Temperature
The correlated colour temperature (CCT) of a lamp is the measure of the warmth of the light emitted from it. It is measured in Kelvin (K). Incandescent lamps have a colour temperature of 2700K, whereas fluorescents can have colour temperatures ranging from 2200K (orange/white) to 8000K (blue/white).

Ensuring that the correct colour temperature is used is essential to any lighting design. If cool colours are used in rooms for relaxation then they will look harsh and uninviting. If warm colours are used exclusively then the rooms may appear dirty and old. Finding a balance between different colour temperatures can be quite difficult and it is worth experimenting with different lamps of different colours to find the right combination.

Colour Rendering Index

The colour rendering index (CRI) is a measure of how well a light source matches a particular spectrum standard called a black body radiator. An incandescent lamp will match the black body radiator, and has a CRI of 100. It is used as a guide to how well light shows colours on a surface. A good example of a very low CRI lamp are the sodium lamps used in some street lighting, giving an orange/yellow light. It is almost impossible to discern different colours below one of these lamps, since they all look the same, and these have a negative value CRI. The CRI of a lamp is a good measure of how well the lamp will show colours. If the CRI rating is in the 90s, then this is exceptionally good; if it is in the 80s it will be good, but not amazing. Anything below 80 is not really suitable for residential use.

Lighting and its function in cinematography

Cinematography is the art and science of recording moving images. Through lighting we can create in these images a visual language that indicates time, place, and three-dimensionality. Lighting can do a lot, but it has several major functions in photographing moving images.


Just as light allows us to see, lighting allows us to record the image. Obvious, right? But we need to consider the following. Our eyes register light through rods (brightness on a gray scale) and cones (color values) and transmit images to the brain. They are very sensitive and have a tremendous amount of latitude in what they can perceive and what the brain can then process or “record.” At the writing of this book there are a lot of very excellent high-definition cameras being used in the profession. They range from the ARRI ALEXA and the RED to the Sony F55. There is also a wide range of “prosumer” and low-budget professional cameras being used for a wide variety of digital cinema and video production, which includes the Sony NEX-FS700, the Canon EOS C500, and a slew of digital single-lens reflex still cameras that can also record video and that all boast 35mm sensors and high resolution rates. They can record an image under almost any form of available light, even under streetlights outside at night or by the light from a computer screen. Amazing! Yet none of them come anywhere close to what our rods and cones can detect. The human eye can see detail in the darkest shadows in a room with only a single candle. It can see details in the texture of the snow on a sun-drenched mountaintop.

Lighting allows film and video to record an image that approximates what the human eye sees. Without enough light, the image, or parts of it, will be noisy, blurry, burned out, dim, and lacking in detail, if visible at all. While a lot of things can be done to the image in digital postproduction, it takes a lot of time, talent, and money—and can degrade the image quality. Even with the most advanced postproduction coloring software, it is still preferable to begin with a full-range, deeply saturated image—something we used to call a rich negative. That means a picture with a defined contrast, full blacks, clean whites that don’t blow out, and a nice full range of in-between levels throughout. We can usually only accomplish this by judiciously adding some of our own lights.

With the new highly sensitive sensors, the need to add light for simple exposure has all but disappeared. That burdensome, nonartistic, technical requirement has been, thankfully, lifted from the shoulders of the director of photography (DP) and gaffer, who can now concentrate totally on the artistic use of lighting. In other words, we now concern ourselves with how much we want the viewer to see and how much we want hidden in the shadows or ignored in burned-out white. In lighting we put light where we want it and take it away from where we don’t want it. We now have more ability to be selective in what we allow the viewer to see—selective in the brightness, in the color, in the contrast, and in the detail.

By using this selectivity, we can direct the focus of the viewer’s attention to what we want the viewer to concentrate more on within the picture. The human eye is attracted to whatever the brightest thing is in its view. Magicians use this to their advantage all the time. A bright flash of light occurs off to one side and everyone looks at it, giving the stage crew enough seconds to hide an elephant and make it appear to disappear (yes, it’s been done). Directors, art directors, and DPs use the same concept. Art directors will give the actress that is the star a more colorful, brighter, or more sparkly costume than the characters surrounding her, thus making her stand out in a crowd. DPs do this with lighting.


Movies and videos are two-dimensional images. But everyone working on the project wants to suck viewers into the world being shown onscreen—we want them to feel as if they are looking into another world through a window. We want them to become so engrossed in the story that they feel like they are in the picture themselves. Lighting suggests a belief in the reality of what is on the screen. We use lighting to deceive the viewer into believing what is happening is real. We want viewers to forget that what they are watching has already happened a while ago and isn’t happening right here and now, and that who they are watching are actors, that the actors are just reciting written lines, and that they are in sets, not real locations. Good lighting renders an illusion of three-dimensionality to a flat screen, making it feel all the more real and making the viewer feel more present. Lighting does this by providing modeling and depth to an otherwise flat image.

The mind rejects pictures that are false and confusing, thus taking the viewer out of the moment and back into the position of sitting looking at a screen. This causes the viewer to separate from the story and examine the image as an image. When this happens, the viewer becomes detached from the story. While viewers certainly can become reengaged, they will not process fully what was going on or being said while their brain was preoccupied with trying to justify the “reality” of the image.

In order to avoid this, the lighting in the image must look “real” or “natural” or at least story-appropriate. Lighting provides logic. The light seems to be coming from natural or logical sources, making us feel we are in real locations. Lighting utilizes light, shadow, color, texture, and angle to give the audience a perspective on the scene taking place. Shadows must be consistent with the “source” of the light whether seen or unseen. We must be consistent to maintain believability. And believability is key to getting the audience to suspend disbelief and become involved in the story.

In order to maintain an illusion of reality, we will want to light the scene as if it were lit by a motivated light source—something that seems believable, such as a desk lamp, a window, or a fireplace. Thus, the lighting we use should be consistent with its source—in color and intensity, texture and angle. This helps the believability of the image, which helps the believability of the story.

These are only two of the functions lighting performs in cinematography. In the next post I will examine the others.

An introduction to stage lighting

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.