Lighting to achieve a certain mood is easy if you work with three basic elements: key, contrast and color.
First, of course, you need to be clear about exactly which mood you're after: sunny, dreamy, macho, scary or any of a score of other emotional states. For instance, midnight lighting is equally dark, blue and contrasty for both strolling lovers and lurking vampires. Beyond the basics, though, romantic and horrific are different animals.
So let's see how to paint emotional light pictures, using contrast, color and, first of all, key. As used here, "key" doesn't mean the main light on the subject, but the proportion of light to dark in the image. We'll work indoors, where you normally do most of your lighting and have the most control.
High-key images are basically light-toned with darker accents. This doesn't mean low contrast; a good high-key lighting design includes a full range of tones from white to black.
Usually, high-key lighting feels warm, cheerful, expansive and energetic. Look at the great screwball comedies of the 1930s and you're sure to find high-key lighting. To achieve this "open" look, typical high-key designs feature thorough key and fill lighting for the subjects, plus lots of light on the walls and floors. Small areas remain darker to punctuate the overall design. If you're working with a limited kit, soft boxes or umbrellas are particularly effective because they deliver wide, even light that helps light the background. In fact, it's hard to keep them off it.
High-key can also mean heat and glare. For emotionally hot interiors, start with a basic high-key light plan and then adjust it by upping the contrast or the overall brightness, by either slightly over exposing or by pumping up the brightness in postproduction.
You can take high-key in the opposite direction: toward a cold, hard, feeling suitable for prisons, bus depots and futuristic settings. The quickest way to achieve this look is to put away your lights and use ceiling fluorescents alone, preferably in a grid ceiling, if you have one. The shadows will be diffused, but they'll show up under your subject's eyes and chins. If you lack fluorescents, then get your soft lights as high as possible and block the performers to stand beneath them.
Low-key lighting produces mainly dark images accented by lighter areas. Film noir classics and dramas like Casablanca use a full gray scale from black to white, but the darker tones predominate.
The basic flavors of low-key lighting are dramatic and powerful. To set the mood, work as much as possible with spots, softening fill lights with screens or spun glass sheets. Backlighting is important, both for the light accent it provides and to separate subjects from the backgrounds.
By taking low-key lighting to extremes, you can deliver spooky, mysterious and menacing feelings. In this approach, you reduce bright areas to the minimum needed to understand the image or, for extra suspense, even below that minimum. This makes the audience strain to identify that huge shape that is lurching toward the plucky heroine. Minimal lighting does not mean poor lighting: make sure you still get a good exposure.
Two ancient lighting techniques work well in scary scenes. First, key the menace from directly behind to create an anonymous silhouette. Then light the heroine from below (as if with the candle she's carrying). As with cookies, keep these effects under control unless you're striving for an extreme effect.
Low key can also mean warm, cozy, safe and romantic. Using a fire as the motivation for key lighting is the most obvious technique. Practical (meaning visible in the frame) lights work just as well. Whether talking in a restaurant booth or on a living room couch, a couple in a circle of warm (i.e. bright) light with darker tones around them looks great.
The range and gradation of the tones from black to white in an image determine the contrast. A wide brightness range (often called a long gray-scale), means that every level from dead black to pure white is present in the image, though this can be harder to see in color than in black and white.
Generally, a long gray-scale is preferred, but to create a soft, passive or misty atmosphere, you sometimes want to avoid black and white extremes and confine your tones to the midrange. To do this, make sure you have plenty of fill light on subjects and broad, even background lighting. Here again, soft lights work best because they deliver naturally low-contrast lighting.
If gray-scale is the range of tones, gradation is the size of the jump from one tone to the next. Normally you want as long a gradation as possible, something like 14-plus steps between black and white. However, for a harsh, stark, brutal or macho feeling, try reducing the number of steps from black to white. To do this, reduce fill light and splash hard bursts of light on backgrounds.
Both contrast range and gradation are easily managed in post, so you may want to light normally for both moods and then make adjustments later.
There's nothing like color to influence mood, whether hot reds, sunny yellows, soothing blues, living greens or violent purples. The production design usually sets the color, but you can enhance it with colored gels over your lights.
Again, warm firelight is the obvious example. Subtler effects include very pale warm gels to give a feeling of glamour or a hint of blue in the backlighting to suggest romantic moonlight.
When working with color, don't forget that the background lights don't have to be perfect in color temperature. For instance, standard household bulbs (around 400 Kelvin warmer than halogen lights) can look great in bedrooms, living rooms and other areas where you want an appealing color tone.
And don't forget the emotional effect of off-camera lighting effects. The ghastly yellow of the bar neon or hotel sign can be truly unpleasant. The revolving red squad car light says danger-danger-danger.
To sum it all up, first decide what mood you're shooting for, then decide whether to go high-key or low. Fine-tune subjects and backgrounds to achieve the right feeling, then use contrast and color for the finishing touches.
Contributing Editor Jim Stinson is the author of the book Video Communication and Production.
[Sidebar: Mood and Style]
Don't confuse mood with style. Where mood is the emotional cast of the image, style is the esthetic approach to it. Lighting styles fall into four basic types:
[Sidebar: Mood It in Post]
Increasingly, editors are enhancing the mood in postproduction. With digital editing, you can make extensive changes in: