I wrote an overview a while back about the different angles of light that a designer employs. This and the next few posts comprise a kind of basic primer, for those interested in lighting who may not have a strong background in it, wherein I flesh out each of those ideas and how they might be used in a design. While the angle article was more theoretical in nature, this series will be about basics and practicalities.
Speaking about the use of backlight I said that it “defines that object as distinct from its background and contextual surroundings.” Backlighting keeps the human form distinct, not only from the background setting, but also distinct from other people and objects on stage. The slight halo effect of backlighting visually breaks up the field of vision and gives us unique entities. With that in mind, I went on to say that it reveals the “[b]ody as existential entity.” Through defining the human form, the subject, as separate and distinct from its context, we bring that form, that entity into our presence as something to be considered and evaluated.
One of the jobs of the lighting designer is to communicate to the audience what we should be looking at. Put simply we place light where it should be and take it away from where it should not be. We focus the attention of the audience on certain parts of the stage or certain performers. We expand the focus to include a large ensemble moment and then narrow that focus to highlight a solo or monologue. While there are many tools available for achieving that goal, the use of backlighting is a powerful one, as we can visually separate the crowd from the scenery, or the lead from the crowd.
Another powerful use of backlighting is the role it plays in defining the space around the performer. Be it through the use of a cyc or simply backlight from overhead, the light not hitting the performer greatly impacts the visual experience of the audience. The cyc example is obvious as it provides a backdrop in front of which action happens. Backlighting from overhead provides a powerful means of lighting the floor and thus transforming the space on which the performer is standing. This can be done through modulating the intensity and making the floor brighter or darker. It could be through the use of color, whereby the designer changes the floor from an icy blue to a deep burning red. It could be through texture where we appear to move from an open space into one shrouded by foliage.
Because the light is moving in the direction of the audience, if you have a backlight and a front light on at the same intensity the effect of the backlight on the floor will be considerably stronger as the backlight bounces off the floor and continues on towards the audience, while the front light continues moving away. This wonderfully simple act of physics provides the lighting designer with a fantastic tool to create vast and multivarious landscapes upon a relatively simple stage. Through modulating intensity, color and texture the stage floor can be transformed such that a performer appears to traverse worlds instead of a mere few feet.
The effect is similar if one is using backlighting from directly behind of from a diagonal position. The main difference here is that the halo effect created by the lighting is different. With lighting from straight back, the halo covers the entire form while the use of diagonal lighting shifts the halo to one side or the other.
Another function of backlighting has to do with how we perceive the stage space as a volumetric entity. Light has the perceived effect of elongating the axis on which the light moves. For example, straight backlight(or top light) will have the effect of making the vertical space feel higher. It will give a feeling of more air between the floor and the borders. Backlighting on the diagonal will have the perceived effect of expanding the floor along all three axes. Some designers say that diagonal backlighting “opens up” the stage. In truth, all lighting does this, but diagonals work on several angles at once while straight backlighting, for example, only effects our perception of height.
The effect of backlight to expand a space can be heightened through the use of atmospheric effects. Smoke, haze and mist are all means of filing the air with particulates that will catch the light and dramatize its already powerful effect. This can be seen quite often in concert situations where backlighting is used almost architecturally to cast beams of color and texture through the air or at the audience. The Tribute in Light, using the natural haze of the city, is another good example of this.
Backlighting is an infinitely variable tool that allows the lighting designer numerous opportunities to transform the visual experience of the audience. From bringing focus or obscurity to a performer to stretching the height of the performance space, backlighting is central to creating the necessary mood and feel of the moment.
