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December 1, 2008 |
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Created and Maintained by: The Photoimaging Information Council |
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Articles |
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Positioning the light. Many photographers would simply leave their flash on-camera. That's certainly doable. We, however, recommend moving the flash off-camera. By moving the flash off-camera and elevating it slightly, you will get more three-dimensional modeling in the face. You get slight shadows under the nose, under the chin and perhaps even under the cheekbones. These shadows help you suggest something of the three-dimensional world in your two-dimensional photograph. It can give the face shape, modeling and depth. Moving the flash slightly off-camera, maybe to the left or right, can be even more advantageous in gaining this three-dimensional rendering of the face.
To get your flash off-camera you'll need something called a dedicated flash cord. This is a high-tech solution that slides into your camera's hot shoe and connects the exposure system, that is the flash metering cell inside the camera, to the remote flash unit. The result is that even though the flash is several feet removed from the camera, you're still getting full TTL control of the flash's output. TTL, of course, stands for Through The Lens metering, and you can buy TTL dedicated cords in various lengths. I think about a three-foot length is adequate enough to get the flash high enough and far off to the left or right to get good modeling.  PHOTO: Denis Reggie Cont... One of the problems often encountered when using the flash off-camera is that in the heat of shooting, the photographer may not aim the flash to optimally cover the entire group. Unless the flash is perfectly aimed, we can get individuals on the left or right of the group in shadow. To prevent this, we manually dial in a widening of the flash beam. You can do this with flash units that have zooming flash heads. We can, for example, set our flash beam so it thinks we're using a 28mm lenses, when in fact we're shooting with a 50mm. Doing so, we broaden the beam of light coming from the flash, making the aiming of it not so crucial.
In all circumstances, we don't have to aim the flash directly at the subjects. Sometimes, when conditions allow, we can bounce the flash beam off the ceiling. The idea here is that light from a broad source is usually more flattering to the human face than light from a point source. When we bounce light off a ceiling, the entire surface of the ceiling becomes the light source, and it can help create modeling and shaping in our subjects' faces. Problems can arise, however, if bounced light from the ceiling can't fully illuminate the eye sockets. Some flash units solve this problem with a secondary flash tube that throws light straight into the eyes sockets, while the main flash head is used in the bounce mode. This not only assures the eyes are well lit, but also places specular highlights on the surface of the eyes, adding a lively sparkle. While bounce flash can improve the quality of the light, it also diminishes the amount of light. Whenever you bounce off the ceiling, you're losing a lot of light to the rest of the room. To compensate for this loss of flash output, we might set a wider aperture, say f/4.  Using 'Umbrella Lighting'. Your flash is at its most efficient, obviously when your aiming it directly at your subjects. This may be too harsh, however, so to soften it we sometimes bounce the flash into a white umbrella that's positioned just off camera. The issue with single-source lighting like this, however, is shadows. If we're photographing a large group, we have to make sure that the light from that single umbrella is reaching every face. If one person's head stops the light from reaching their neighbor's face, that's a problem. It's not so crucial an issue if you're using two umbrellas, which light the group from two sides.
Umbrella lighting has its challenges. If you're to get the lights high enough above the camera position for good facial modeling, for example, it requires high ceilings. You need space to put up the light stands, and, unless your strobe's transformers are battery-powered (something I highly recommend, by the way), you're also going to need electrical outlets. Finally, umbrellas can be a problem outdoors in the wind  PHOTO: Denis Reggie Cont... These are minor cautions, however. If you're going to get serious about photographing groups, you'll probably want to try umbrella lighting. If you do this, however, you'll have to give up the TTL exposure cords mentioned earllier, and start metering your portraits with a hand-held meter. With umbrella lighting, the means of triggering the off-camera strobes also becomes an issue. Of course, you can use a normal PC cord. This is a cord goes from the X-sync terminal on your camera to the strobe unit. The problem with a PC cords is that eventually someone will trip over them, especially if there are children about. Sooner or later, someone is going to trip over a PC cord, probably pulling down your umbrella light too.
A better way to trigger the flash is wirelessly. These systems send signals from the camera to the flash, instructing the flash when to fire. A wireless remote triggering device will add to the expense of your system, but the benefits often warrant it. There are several types. Optical slaves work with bursts of light. Radio slaves send signals in either analog or digital form. We're currently using a digital system called Pocket Wizard that's distributed by Bogen Photo. Digital systems can be used almost anywhere and they aren't adversely affected by local conditions. They're impervious to the noise generated by a wireless microphone, for example, something that could falsely trip an analog radio slave. For a totally wireless setup, by the way, we also sometimes use a separate wireless transmitter for the off-camera meter, too. It fires the umbrellas wirelessly, in a similar manner to the transmitter on the camera.  PIC's Point n' Shoot Tip As long as your camera has a built-in hot-shoe, you can get your flash off-camera, just as Reggie recommends. One way is to put a sheet or two of translucent plastic over your camera's built-in flash to dim and soften its output a bit. Then use an inexpensive auto flash (like a Vivitar 283) as your off-camera main light. Connect it to the camera's hot shoe via a non-TTL off-camera sync cord.
Set your point-and-shoot to an exposure mode that lets you predict what aperture the camera will set (often the Portrait Mode will automatically set the widest aperture, for example,) then simply set that aperture and the correct film speed on the auto flash control panel. As long as the flash and the camera are approximately the same distance from the subject, good exposure will result. Try this. You'll be pleasantly surprised at how improved your group portraits will be and at the onslaught of compliments that ensues! 
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