FUNCTIONS OF STAGE LIGHTING
While most textbooks teach that there are four functions of stage lighting, I believe there are seven:
If the audience can't see the actors, everything else the lighting designer does is a waste of time. Studies have shown that visibility affects our ability to understand spoken speech. This doesn't mean that the audience must see everything all of the time; a German director named Max Reinhardt once said that, "The art of lighting the stage consists of putting light where you want it and taking it away from where you don't want it."
(or "atmosphere") "Mood" is the evocation in the audience of the appropriate emotion. Many designers err in paying attention to mood to the point where visibility is sacrificed.
The act of painting a picture, in this case, with light.
Sometimes called "realism", but that's not always accurate, since not all plays - and certainly very few ballets, modern dance pieces, and operas - are realistic. It's the same quality that Stephen Colbert refers to as "truthiness".
What are we reinforcing? Everything.
We reinforce the playwright's text:
In A Midsummer Night's Dream, Puck has the line, "And yonder shines Aurora's harbinger," meaning the dawn. The lighting designer can reinforce this by providing the first rays of dawn.
We reinforce the work or the set and costume designers:
We might use colors that flatter or complement those used by our colleagues.
If the sets and/or costumes are sculpted and lush, we might light them so as to highlight their 3-dimensionality.
Revelation of Form:
Decide on the level of 3-dimensionality you want the audience to see. In some productions, you might want a "flat" look; in others – particularly in dance – you might want a more sculpted look. A case could be made that revelation of form is part of composition or mood; however, it's important enough (in some productions, at least) to be a stand alone function.
The blackout at the end of a climactic musical number! The slow fade to black....