Basic 3 Point Lighting
Before we begin looking at an example let's consider what the function of lighting is. Lighting can be used to add mood and drama to a shot, but it's overriding function is to describe 3D objects onto a 2D area, be that a computer monitor, a print out or a cinema screen. To put it another way, the light is used to "model" the objects so that on a flat surface we can tell what shape they are, and how one object relates to another.
When considering what makes good lighting we need to balance the aesthetic requirements of the shot, lightness/darkness, colour etc. against the need to be able to see what is going on in order that the narrative may be advanced.
OK, so we know we want to model the objects with light, so their shapes become apparent to us, but how do we do that? To begin with take a torch and in a darkened room shine a light on different objects and see how they take the light and how much of their shape is revealed to us. For example if you light something front on, you will be able to make out its outline but shapes within that outline may not be so obvious. If you place the light above and slightly to one side the shape will probably be better defined. This main light is THE most important light as its placement influences all others. It is known as the KEY LIGHT. Let's look at a specific example.
The Key Light
A single key light
By placing the key light above and to the left we can see the volume of the oranges (i.e. that they're spherical). We can also see that they are on the floor by the shadows cast and that they are stacked on top of each other. However the image is lacking detail in the shadow regions and is a bit brutal. In order to fix this we need to add another light to the right of the oranges to add some illumination to those darkened areas. This light is called the FILL LIGHT. Let's look at what this light contributes to the scene.
The Fill Light
The fill light
The job of the fill light is to illuminate those areas of the image which are in shadow when the key light is placed. It should be pretty obvious therefore that the fill light is placed after and in relation to the key light. As the job of the fill is only to allow us to see a little more detail it should not be as intense as the key light. Look at this example; the key light is about 2-3 times brighter than the fill. Let's take a look at how the key and fill light work together.
Key and Fill
Key and fill light
The image now looks a lot better than it did with just a key light. The image has more depth and detail. It is neither too dark, nor too washed out. However there is something more we can add. The right side of the oranges are getting a little lost against the background. In order to counteract this we can add a RIM LIGHT.
The Rim Light
The rim light
The rim light is placed behind the objects being illuminated and is angled so that the light glances off the surface of the object at the narrowest angle. The intensity of this light is often quite high, often brighter than the key. Due to its intensity and placement it creates a line of bright light around the object and in doing so lifts the object away from the background. The rim light is principally used to ensure that a dark object does not blend in with a dark background. OK now the lighting is complete let's examine the finished result.
The Finished Render
Key, fill and rim lights
The rim light has lifted the oranges away from the background, the orange at the bottom right was in danger of disappearing into the background but is much better modelled now. The image still has contrast and a good range of tones from black through to white. The floor shadows and the shadowing of one orange onto another are still there showing each object's relationship to the next, but you can see detail even in the shadow areas on the fruit. All that's left to do is a little bit of tweaking in post.
The Finished Image
Key, fill and rim lights
By adding a subtle glow to the strongest high-lights (those created by the rim light) and by softening the image to limit that super-crisp "CG look" the image can be improved a little more. You can tweak an image indefinitely like this by adding noise and so on but I've decided to leave it like this.
In the above example we have taken a look at the most basic, yet flexible lighting set-up which, with tweaks to the intensities, can be used to light almost any situation. This does not mean that you shouldn't experiment with light placement as long as you remember to place the key light first and let the other lights take their cue from it. Look at the work of the great painters of light like Vermeer or Rembrandt or at photographers like Irving Penn or Horst P. Horst or the great cinematographers like Gregg Toland or Gordon Willis.
One book I really recommend is "Painting with Light" by the late, great John Alton. This book is over 50 years old now but is still the best reference work on lighting for film. I got the idea of using oranges as my "models" for this tutorial from him. As you can tell we have only covered the tonality of light here. I'll probably do another tutorial when I get the chance covering colour and lighting. I hope this has proved useful to you and given you some ideas of your own about the art of lighting.
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