There are a really an infinite number of different ways that you can set up lights in a portrait studio, but there are a few that portrait photographers use over and over again. One of these is "split lighting.” Split lighting is exactly what it sounds like—it's a light that divides the face into two equal halves, one side the highlight side and the other the shadow side. Because of the high contrast between one side of the face and the other, split lighting is used to create a dramatic effect. You may have heard it referred to as “old Hollywood lighting," because it's the style of light that they often used in the early days of Hollywood to communicate drama to viewers.
Lots of drama by Flickr user paris20vt
Split lighting is one of the simplest lighting setups because it requires only a single light, placed at a 90° angle to the left or right of your subject. The exact position of the light will depend on the person's face, so it's helpful to use continuous lighting while you're setting up so that you can watch where the shadow and highlight sides fall on the person's face. You can move the light source so that it is slightly behind the person's head if necessary—the key is to make sure that you get that defining line between the shadow side and the highlight side in roughly the center of the face. Ideally, you want the only light on the shadow side of the face to be on the eye. And keep in mind that some people don't have the right face for split lighting, so despite all your best efforts you may not achieve that classic split-lighting look no matter where you place the light.
To make this technique work requires some help from the subject himself—because you're going for a straight line down the center of the face, it's important for the subject to keep still until after the exposure (or set of exposures) has been made. A slight change in the position of your subject's head could change the look of that split lighting pattern, which could have the effect of making the image appear uneven.
Split lighting vs. broad and short lighting
Now, you can also use this technique when the subject is not directly facing the camera, but the name of the technique changes depending on where you place the light source. When your subject's head is at an angle to the camera, there's a "short" side and a "broad" side: the "short" side is the side that is most distant from the camera, which appears to be narrower than the opposite side. And the broad side is the side that's closest to the camera, which appears wider than the opposite side.
Broad light by Flickr user jaimi.lammers
Broad lighting, then, is when you place the light on the side of the face closest to the camera, or the broadest part of the face visible to the camera. Using the light on this side of the face has a widening effect, but it can also de-emphasize imperfections in the skin such as blemishes and wrinkles or freckles.
The opposite of broad lighting is short lighting. With short lighting, the highlight side of the face is the side farthest from the camera, or the shortest half of the face that the camera can see. Short lighting is great if you want to slim down in your subject’s face (and who doesn't appreciate that?)
Allison by Flickr user Katelyn Kenderdine
Just keep in mind that your goal should still be to place the division between the shadow and highlight sides of the face down the bridge of the nose—to do this, you need to move the light source as the face moves.
Catch lights are an important, though often overlooked detail in any portrait, split-lighted portraits included. A catch light is that little white highlight that makes the eyes seem to sparkle—without them, your portrait can look dull or even lifeless, despite the fact that the subject is obviously a living thing (remember that catch lights are important not just for human subjects, but for animal subjects as well). But here's where it gets complicated—with split lighting, the light is set at a 90 degree angle to the subject, and sometimes it is placed slightly behind the subject in order to achieve that classic split lighting effect. Because of the placement of the light, it's entirely possible that you'll end up with a subject that has a catch light in only one eye. Now, while you might be tempted to add the catch light after the fact in post-processing, catch lights are almost always more convincing when you capture them naturally, so it's better to just move the light forward a little until you can see a catch light in both eyes.
Capturing catch lights isn't difficult but it is something that you have to think about, so make it one of the steps you go through every time you shoot a portrait, whether you're using split lighting or some other lighting technique. Before you hit the shutter button, just do a quick review of your subject's eyes. Are there catch lights? If not, you need to make sure that you add them.
Foto Estudio: Split Light by Flickr user Fernando Serer
When to use split lighting
Split lighting is often used to create drama—it doesn't tend to be the most flattering light because it can suggest a sort of angel/devil personality. In other words, you've got evil lurking on the shadow side of the face and good lurking on the other side. This is great for characterizations and to cast doubt in your viewers' imagination about the motives of the person who is featured in the portrait.
You will see split lighting used more often with men than with women—it does have a sort of masculine note, and doesn't tend to be the go-to lighting to use with less masculine subjects like women and children. Of course as you can see from the examples I've used in this article that the decision to use split lighting is always subjective, and the "men only" guideline is probably something you'll find more with traditional photography than with modern photography. Remember that you can also increase or decrease the amount of drama in any photograph by moving the light so that it becomes softer or harder. Generally speaking, the more even the shadow and highlight side are, the less dramatic the photo will be, while the darker the shadow side is compared to the highlight side, the more dramatic the image will be.
Split lighting without studio lights
The beauty of the split lighting technique is that you don't need a studio lighting kit to achieve it, or even a single strobe. You can achieve beautiful split lighting effects using a light source that is in every single home (unless you live in a basement): a window.
Window light is abundant and free, and because it is a single light source it can be used to create that split light effect without much effort. Just place your subject next to the window at a 90 degree angle (just as you would if the window was a studio light that you could move around). To change the contrast or drama, move your subject closer to the window or away from it. A subject placed close to the window will appear much more dramatic, with a deep shadow side and a bright highlight side, while a subject who is more distant from the window will have a softer shadow side and a more gradual transition between the two extremes of highlight and shadow. To intensify this effect, choose a window in a darkened room, or place the subject against a black background. If you're generally unhappy with the amount of contrast you're getting in the photo, you can also use a white reflector to bounce light onto the shadow side of your subject's face—move the reflector closer to brighten the shadows more, and move it away to brighten them a little less.
Remember that you need catch lights in your window-lit portrait as well—if you aren't seeing them, you can use a reflector to create them, or you can adjust the position of your subject incrementally until they appear.
Split lighting is one of the easiest lighting techniques to learn because it is very straightforward and simple—you need only a single light, and it doesn't even have to be a professional studio light. But split lighting should also be used sparingly because it does also tend to characterize your subject, or create a personality for him that may or may not actually be present. That's why you'll often hear it called "comic book villain" lighting—spend a few minutes leafing through any comic book and you'll almost certainly find a drawing of the villain that's been rendered with dramatic split lighting. Old Hollywood loved this look because it creates a sense of intrigue, a question about a character's motivations and true intentions, and that makes for compelling storytelling. But is that what you want for your portrait subject? Maybe, but if not, it's best to use the split lighting effect in a limited way and then go on to master some of the other techniques we'll be talking about this month.