Silhouettes and Backlight

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There are few lighting effects more evocative than the silhouette. While showing line and form to great advantage, and without the visual detraction of many body “flaws,” it’s the very fact that so much of the image is left to the viewer’s imagination that makes the silhouette so successful.

Just as there are many ways to approach a silhouette, there are many ways to light it. Let’s begin with the simplest approach: lighting a white wall or background sweep. In my opinion, it’s best to do this with softboxes because parabolic reflectors throw uneven light, usually with a slight hotspot, and we want to light the background as evenly as possible. Umbrellas can be used, but they tend to spray the light more than softboxes. If you use umbrellas, be sure to place gobos between the lights and the model.

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In most lighting scenarios, it’s difficult if not impossible to light the foreground as brightly as the background if you’re using a simple paper sweep. Once you add light to the foreground, some will spill onto the model, ruining the silhouette effect. With a flat foreground/ background, you’ll have to do some Photoshop work to get an even white. (Don’t worry. It’s not difficult, even if your model is wearing white clothing.)

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For a perfect silhouette, you’ll also need to keep spill from the background off the model by placing her as far from the background as possible. It’s also a good idea to use gobos between the lights and the model, and my preference is black bookends. While it’s almost impossible to avoid all spill, more control will allow for the darkest silhouette. Personally, I think a little wraparound spill light makes a more believable silhouette, as it lends some dimension to an otherwise visually flat surface. If you prefer a darker silhouette, the easiest way to accomplish it is to move the model farther from the background, so any spill will fall off before it reaches the model.

Begin by placing two lights with identical softboxes about 18 inches to 2 feet from the background, with the height of the strobe heads equal to 3/4 the height of the model, and at equal distances from the edges. As a starting point, aim the two lights at each other, rather than at the background. The idea here is to feather the light across the sweep, to get as even an exposure as possible. This will be easier if you can figure out how much of the background width will actually be represented in the image, which will depend on the focal length of your lens, how far the subject is from the background, and how far the camera is from the subject.

Begin metering at one end or the other, moving the meter in 1-foot increments and making a mental note of how the light falls. You may see distinct differences in the exposure readings of the light as you move from one side to the other, which indicates that one light or the other will need to be angled differently. Feathering a light takes practice and is usually best accomplished in small movements, but the result will be an evenly lit background. If you’re feathering lights for the first time, you’ll be amazed when you see the final angles of the light; it appears their placement defies logic, as you can see in diagram 5A.

Once you have the lights balanced and blocked off, set your camera 2/3 to 1 stop brighter than the meter reading. If your meter reads f/11, for example, an extra 2/3 stop means f/9, which will ensure that most of your evenly lit background will be too bright to register as a flat surface or to show any texture.

An easy way to get a more perfectly white foreground is to buy at least two sheets of shiny white tile board, a Masonite-based, 4×8-foot panel typically used as a bathroom wall covering. It’s a tough and inexpensive material found at major hardware or remodeling stores. Lay the sheets on the floor so they overlap toward the background, to maintain a visually unbroken white surface. The tile board will reflect white light from the background better than any paper surface. You may also use sheets of white Plexiglas, but you should lay white paper underneath them as they are somewhat translucent. They will give you a cleaner, whiter reflection than tile board but cost about three times as much. Neither will present a “perfect” solution, however.

If there’s any downside to using tile board or white Plexiglas, it’s that you may pick up a reflection of your subject in the surface. Usually this extra reflection is desirable because it’s somewhat unusual and something many photographers don’t know how to achieve. You’ll get the deepest silhouette with both gobos in place, but the foreground will show a shadow. You can easily fix this in Photoshop. See image 5.1.

If you remove the gobos or reposition them to allow more light on the foreground, you’ll add detail to the image as light wraps around the subject. Again, there will be some darkness in the foreground. I removed the camera-left gobo, adding detail to that side of the model and brightening the foreground. See image 5.2.

When both gobos were repositioned, the foreground was brightest, but the silhouette effect was diminished. Light spilled over and lit some of the model’s face. The effect is not necessarily unwelcome, but it does change the look. See image 5.3.

A BASIC PHOTOSHOP TRICK

You can make slightly gray background areas in your images white by taking the time to make some quick adjustments in Photoshop. Here’s how it’s done:

First, select the light-gray areas using the Magic Wand tool. See image 5.4.

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Once the area is selected, go to Select>Modify> Feather, and set the Feather radius from 1 to 3 pixels (the latter will provide a softer transition against clothing and may even help hold an edge). See image 5.5.

Use Levels to increase the brightness of the whites. If your subject is centered against the light, the brightest area of the image will be directly behind her and already be perfectly white. Feathering the selection will help retain detail in many of the delicate areas, like stray strands of hair. See image 5.6.

This trick will work with any silhouette technique, provided the spill light and exposure are controlled. See image 5.7.

SOFTBOX AS SOURCE

A large softbox (a medium softbox will work for tighter compositions) or a modifier such as a Halo may be easier to deal with than trying to evenly light a large expanse of background, although they present their own problems. If your softbox can be equipped with an interior diffuser, please attach it if it’s not already in place. You’ll want the extra diffusion to even out the light as much as possible.

Begin by metering the flash output directly from the softbox fabric. If your flash meter allows it, retract the dome so you can lay the meter flat against the fabric. This will give you the most accurate reading of the light’s strength since there are no opportunities for even the mildest shadow along the contour of the dome.

For accuracy and control, power your strobe to read to a whole stop or a perfect third, as doing so will make any testing easier to document and understand.

I’d recommend you set up a test, beginning with the metered aperture value and shooting one image per 1/3- or 1/2-stop aperture increase. Examination after downloading will give you an excellent idea of how your subject will be affected by various exposures. This image was made with an exposure 1 stop greater than the metered value of the softbox. Notice there is a slight vignette at the corners, where the spread of light out of the box is weakest, but that’s a minor problem that can be easily fixed. See image 5.8.

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PLEXIGLAS AS SOURCE

One of my favorite lighting tricks for partial silhouettes is to hang a 4×8-foot sheet of 1/8-inch thick milk-white translucent Plexiglas about 4 feet in front of a large softbox (a medium softbox will work but may confine your composition slightly), then place my model directly in front of it. The Plexi acts more like a large fiber optic, spreading the light more evenly and consistently than a fabric diffuser itself. It will flare, but not as much as a standalone softbox, and will produce nice edges with wraparound light. See image 5.9.

You don’t need to buy an expensive background hanger mechanism to hang the Plexiglas or seamless paper. You need two light stands (extendable to at least 8 feet), four squeeze clamps, and a 10-foot length of aluminum fence tubing (available at any major hardware store). Place the clamps over the tops of two light stands and place the aluminum tube across the handles. With the stands set just below 8 feet, simply hold the Plexi against the tube and use the other two clamps to anchor it to the tube, and you’ll be in business.

My preferred exposure for almost everything I shoot this way is 2/3 to 1 stop over the meter reading, which is made as it was for the softbox, with the dome retracted and flat against the plastic, aimed at the light, and metering the light that comes through the diffusion panel. At +2/3 stop, the background is perfectly lit, almost totally white, and with enough wraparound to illuminate the inside edges enough to see skin tone and add dimensionality. The Plexiglas is difficult to hang (it’s easier with a second pair of hands), but it’s worth it for the quality of the light you’ll get from this setup. At the time of this writing, a 4×8-foot sheet of 1/8-inch Plexiglas cost about $75.00. Look under “Plastics” or “Plastics Supply” in the Yellow Pages for the nearest vendor or check the Internet for availability in your area.

You may, of course, make silhouettes against any other color background, including colored Plexiglas, or cover the source with a colored gel. You may also place white tileboard on the floor to reflect whatever color comes through.

ADDING DETAIL

Regardless of the method used to create a silhouette, detail can be easily increased by moving in a white bookend or other reflector to catch some of the light coming through the background and send it back to the model. The amount of light will vary depending on the type of reflector used, its distance from the subject, and how much of the form you wish to reveal. See image 5.10.

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LASTOLITE’S HILITE

Another of my favorite methods for producing beautiful silhouettes, as well as perfect high key backgrounds, is a super-large softbox made by Lastolite, the HiLite. Available in a number of sizes (mine is 6×7 feet), it’s a softbox that works like none other. For example, lights are loaded into the side of the 18-inch deep unit, so the footprint on your studio floor is smaller than what you’d expect for such a large piece of gear. Also, the fabric is different from that of a typical softbox and will disperse the light more evenly. The best part? It collapses into a shape that’s 1/4 its setup size and comes with a carry case for location shooting. See image 5.11.

When it’s used without any reflectors or bookends, the silhouette effect is fantastic. Image 5.12 is from a series of shots for which the aperture was set 1 stop brighter than what was read off the background. The special fabric of this box spreads light so evenly that it produces a perfect, clean white, from corner to corner when used in this manner.

You can re-create, to some degree, the look of a supersoft softbox by hanging a large sheet of cotton cloth, as tightly as possible to avoid wrinkles, from light stands and/or supports. You will almost certainly have to do some Photoshop work when dealing with fabric in this manner, but it’s simple. The only problems you’ll see are minor wrinkles in the fabric at the edges and, perhaps, a slight shoot-through view of the light behind the fabric.

I once bought a huge bolt of fabric, about 8×40 feet, which I used to ring 75 percent of a large machine. I lit the machine through the cloth, using the next technique in reverse, creating soft highlights and even light over its entire surface. I’ve used this piece of cloth many times as a makeshift background. While I can’t use its full length in my studio, I have used it to create backlit backgrounds larger than the HiLite. I’ve also found that, if I double it up, I won’t have the same problems with shoot-through light, though the amount of light coming through the cloth will be significantly reduced.

I used my largest traditional softbox (4×6 feet) and set it about 8 feet behind the sheet of fabric so the light would spread evenly over the back of the cloth. The model and the foreground were set immediately in front of it to appear as if a stained and finished piece of plywood, the “stage,” was butted up against a pure white background.

The exposure was measured, into the cloth, at the center of the set. I opened up my camera’s aperture 1 stop over that reading. Even so, One other note: because the background was so much larger than the HiLite, there is more wraparound light in play. The result (image 5.13) is a somewhat diluted silhouette, but it’s still gorgeous.

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We choose our models for a number of reasons, both physical and social, and we’ll often structure the shoot to highlight their physical attributes. Depending, of course, on what it is we wish to accent, a strong backlight can become a remarkable background, especially when paired with an additional accent light that will create a partial silhouette.

The base exposure for image 5.14 was 1 stop over the measured meter reading at the fabric of the HiLite. An additional light, a beauty bowl (without a grid), was attached to a boom and positioned at a slight angle over the model’s head to light her beautiful red hair. It was powered to the working f-stop of the camera, 1 stop over the power of the HiLite.

TRANSLUCENT DIFFUSER

You could certainly use a translucent diffuser as a light source. Smaller sources, such as some made by Photoflex, will work well because of their size. Smaller sources mean less wraparound light, so the silhouette will be more intense and show less detail.

Begin by hanging a translucent diffuser from a frame or from a boom arm. The diffuser may be circular or rectangular, that’s up to you, and you may need to retouch some edges if you want the diffuser to appear as if it’s not supported. I used a large, circular diffuser for image 5.15, hanging it off a boom arm and digitally removing the strap and support in my final image. I set a strobe with a 40 degree grid on a stand about 4 feet behind the diffuser, aiming the light dead-center to the white field, illuminating the diffuser completely, but without spill. It was a smooth and easy solution to create a silhouette with minimal wraparound light, mostly because the source, the diffuser, was relatively small compared to others that you’ve seen, but also because the fabric of the diffuser is different from that of regular softboxes or the HiLite. As you’ve seen from these samples, every fabric, like every modifier, has its own personality.

The diffuser was clamped to a boom arm by its strap and lit with a 40 degree grid, aimed at the middle of the diffuser from about 5 feet behind. All traces of the strap and light stand have been retouched out. The camera’s aperture was set to 1 stop over the actual value of the light coming through the material.