Video transcript
Introduction to lighting – 02 Basics of lighting technology

>> Back to video

[music playing]

LINCOLN GIDNEY: Hi, everyone. My name's Lincoln Gidney. I'm a technical theatre tutor. And this is our second lesson on the basics of lighting design.

Last time, we talked about some of the basic concepts in design, such as focus, direction, colour, and shadow. And today, we're going to be talking about some of the basics of lighting tech and how we achieve these effects. We're going to talk about what makes up a lighting fixture, how we mix colour, and how we get our lights to function.

You won't need any extra materials for this lesson. But please note that some of the more technical aspects of the lesson are at times a little bit simplified. Some of the things we talk about start to land on physics and computer science a little bit. And if you're interested in those parts, I really recommend you research further. There are some great resources online that can help deepen your knowledge.

Lighting designers like to use a lot of slang and jargon. So it's important that you have a good idea about what we're on about. If you ever hear me talk about a lamp or a fixture, they're sort of synonymous. I'm talking about the physical light itself. The way I think about it is if something is shining light on the stage, you can consider it a fixture.

And there's three main parts to any fixture. There's the globe inside the light, which shines and emits light. There's the lens at the front, which generally directs the light and shapes it in some way, and the housing, which keeps everything safe.

We're going to first talk about the globes. There are two main types of globes. There's LEDs and incandescent or conventional globes. Incandescent or conventional globes are an older style of globe. How they work is, inside the globe itself, there's a coil of metal wire called a filament, which, as electricity flows through it, it begins to heat up and glow, emitting light.

More modern lights use something called an LED globe. That stands for Light-Emitting Diode. And these emit light through a much more complex process. But suffice to say, they're a lot more energy efficient and don't heat up as much.

These different globes have their own pros and cons. Incandescent globes tend to draw an incredible amount of power. And as a result, they're not exactly environmentally friendly. Also, if they've been on for a while, they will get to incredible scorching temperatures, making them unsafe to handle.

But they're really commonplace. You'll find them in theatres across the world. And a lot of designers consider them to have a more beautiful, warm, natural quality of light.

On the other hand, LED lights are newer. They're, as a result, a little bit more expensive. And they require quite a bit more technology to get them to work. I'm going to talk about that later in the lesson.

Also, many designers consider them not to have such a nice quality of light. They tend to be a bit more artificial and cold in the light they emit. But they're much more resilient. And the functionality they have is much wider than the incandescent lights. They're also safer, as they don't really heat up as much. And they're much more energy efficient.

On a more practical level, LEDs are a bit more difficult to repair than conventional lights, due to some complicated onboard electronics. But many are able to change the colour of light they emit, which really isn't feasible with most conventional lights.

I mentioned before how the vast majority of lighting fixtures have a globe and a lens. The lens is really important in lighting design, as it shapes and directs the light that the globe emits. In fact, most lighting fixtures are defined by the type of lens they have. And right now, we're going to go over some of the most common lighting lenses that you might find in a theatre.

First is the incredibly common Fresnel lens. Named after this guy, a 19th-century French engineer, the defining feature of a Fresnel lens is this ripple pattern in the glass. As light passes through this pattern, it is diffused and dispersed, resulting in a beam with a soft, even edge. These lights are great for washes and nonspecific areas.

The way we adjust most Fresnels is through either moving the light itself, as in panning, tilting, or moving the fixture around on our rig, or by moving the globe closer or further away from the lens. This has the effect of either widening or narrowing the beam.

One of the other main types of lights we have is what we call a profile. A profile generally has one static, nonmoving globe and two curved lenses in front of it, which can be moved independently of one another. Moving them around allows us to change the size and the focus of the beam of light, which means we can have a light that has a hard or a soft edge at pretty much any size. We love using profiles for things like spotlights and highlighting areas of the stage.

We can also change the shape of our lights with a couple of simple devices, the first of which being barn doors, named as such because, well, they look like barn doors. And what they do is they cut off certain parts of the beam after it exits the lens and shape the light with straight edges.

Shutters, also known as knives, achieve a similar effect, except they work inside the light by cutting off the beam before it hits the lenses. And finally, there are gobos, which are small metal slides that, once again, we put inside the light, which can be used to make more intricate, interesting shadows.

There are hundreds of different types of light out there. To name a couple of the popular ones, there are PAR cans, floodlights, movers, follow spots, and really so many more. I encourage you to look up some of these lights, see what effects they create, and think about how you might use the fixtures in your own designs.

Last lesson, we talked a lot about how colour imparts meaning. But how we create and perceive colour is just as interesting. Colour is really integral to design. But in order to know how it works, we also have to be comfortable with some science.

White light, which most fixtures output by default, is actually a combination of all the colours of the rainbow. We see this when we split light through a glass prism. However, our eyes they cheat a little bit and actually only detect red, green, and blue light and mix them together to create all the different colours. We can use this fact to create specific colours we want to use in our design. This is called additive colour and is the principle that LED lights use to create colours.

Your phone and computer screen work on the same principle. They all have tiny red, green, and blue LEDs inside them, which your eyes combine to create different colours. Using these different intensities of red, green, and blue, we can create an incredible range of colours.

There are many different ways to define and label the colours created this way. The most common one is called an RGB value, which stands for Red, Green, and Blue value, which is usually three numbers that represent the intensity of each Colour. Each Colour is defined between 0 and 255, because 255 is the maximum number that a simple computer can count to.

So 0, 0, 0 would be black, as none of the colours have any intensity. And 255, 255, 255 would be white, as it's an even combination of all the colours. For instance, if I was to do 255, 255, 0, that would be a yellow Colour, as it's an even mixing of the red and green value with no blue.

Remember, our eyes make white through mixing red, green, and blue. So if I have a white light and subtract all of the green and the blue from it, what am I left with? Red. And this is what the gels do. They subtract elements of the light to make the desired Colour.

A result of this, though, is that it's very difficult to mix gels. If we think about putting a red gel and a blue gel in front of each other, what's going to happen? Well, the red gel is going to subtract all of the green and the blue light. And then the blue gel is going to subtract all of the red, leaving us with nothing.

This is why we call it subtractive Colour, because we subtract elements of red, green, and blue from the white light to make the colours we want. It should be noted that it's not as easy just to play around with different colours when we're using gels, as each gel has a really specific mix of pigments in it, to make the Colour effect we want.

However, there are a few companies which have huge catalogues of gels, which you can sort through and order the ones you need. The most popular sellers are companies called Rosco and Lee, which both have their own unique way of labelling gels, called Rosco and Lee numbers. Also, they will sell gels that have textures on them, creating a whole new range of different lighting effects.

It's also important that you understand how we get our lights to function the way we want them to. This is slightly different if we're talking about incandescent or LED lights, so we'll go over both. But first, there are a few things to note.

Stage lights, even LEDs, draw a lot of power and so require specialised power outlets. It's not a great idea to go plugging in your stage lights into your regular household outlets. Most theatres have something called triphase power outlets, which can draw much more power and deal with much higher voltages.

Also, the way we send information to our lights is through something called a lighting board or a lighting desk. Each variety of board has its own functionalities and capabilities. And there are hundreds of different makes and models. So we won't go into the specifics of any one, but they all share the same trait, that they are how we tell individual lights to do something. All information and instructions come from the board.

We mentioned briefly that incandescent globes emit light as electricity flows through the filament. In fact, how brightly they shine is dependent on how much power they are receiving. So what we do is connect each light to an outlet in a thing called a dimmer, occasionally called a distro.

The dimmer is in turn plugged into a special triphase outlet and has two functions. First, it works as another fuse box, making sure that any individual light doesn't receive too much power. Also, it takes information from the desk and varies the amount of power going to each outlet, and therefore each light, dependent on the instructions from the desk.

So basically, how we get our conventional lights to work is we plug them into the dimmer, which takes power from the triphase and information from the desk and varies the amount of power going to each light depending on the instructions from the desk.

Now, getting LEDs to function is a bit more complicated than getting conventional lights to function. First, we're going to have to understand what is the information coming from the desk. Lighting technology sends information through something called DMX. DMX stands for Digital Multiplex. But it's easiest to think of it as an information signal.

DMX is broken down into individual packets of information called DMX channels. Each one of these channels has a value, which is basically between 0 and 100%. So you can think of a DMX channel as an envelope containing a DMX value, which is an instruction.

Now, we can have hundreds of these DMX channels at any given time. So we need a way to identify which one to use. So what we do is we label each DMX channel with a unique number called a DMX address. So to continue with the envelope analogy, a DMX value, which is the instruction, goes into a DMX channel, which is the envelope, and has a specific DMX address, which is the label telling it where to go.

OK, so how do we use DMX to control our lights? LED lives differ from conventionals as they require a full nonchanging power supply at all times. They all have these little onboard computers, which tell the LEDs what to do, rather than relying on a changing power source. These computers take their instructions from you guessed it, DMX.

If we look on the back of a light, you can see that there's a power socket, a DMX socket, which we connect directly to the lighting desk, and a little screen so that we can control that onboard computer. What we do is we tell that computer a specific DMX address to look for. So as the lighting desk sends information through all of those DMX channels, the computer looks for the one channel that it's addressed to and only reads the instructions from that channel. That's how we get different lights to do different things at the same time.

Remember that each channel sends only one DMX value from 0 to 100%. But the beautiful thing about LEDs is they can do more than one thing at once. So an LED fixture might read from a whole bunch of different channels simultaneously. For instance, it might have different channels for the amount of red, green, and blue it's outputting so that you can mix and change colours on the fly. Advanced and expensive LEDs might use tens or even hundreds of channels at the same time for a wide range of functions within the same light.

Of course, the way we hook up our LEDs is a bit different to how we hook up our incandescent lights. As they need constant power, we generally just plug them into a different dimmer, which outputs 100% power at all times. And then we connect each individual light into the board with what we call a DMX cable, which just carries all that information.

We can actually create a chain of lights that are all connected via this DMX cable. And that will also work. That's called daisy chaining the lights.

Now, what we've covered is what DMX is and what it does, how we connect conventional and LED lights, and how we get them to function in the way we want them to. In this lesson, on the technical side of lighting design, we've covered the parts of a light, basic Colour mixing, and how lights function. As a few activities, I would encourage you to research different types of light, see what effects they create, and think about how you might play with these lights to realise concepts in your design.

Also, see if you can recreate some of the effects we've talked about today using household materials. Maybe you might use some cut-out cardboard and a torch to create your own gobos.

The next lesson on lighting design will take the ideas from the last lesson about concepts in design and the technical knowledge from this lesson and apply them to a text to create your own design and your own lighting plan.

My name's Lincoln Gidney, and I really hope you've enjoyed the lesson.

[music playing]

End of transcript