Mixing Flash and Ambient Light

Combining light from an off-camera flash with ambient (available) light—commonly referred to as using fill flash—is a technique you can use to capture the details often lost when a scene has sharp variations in contrast.

Let's look at the photographs for some examples of how fill flash works.

Image 1:Roberto. It was midday and like many people who live in the tiny town of Tequila, Mexico, Roberto was standing in the shade to escape the intense sunshine. This "open shade" location, out of the direct sun, was a perfect situation for the use of fill flash.

Often a photographer will place a flash unit on the hot shoe of the camera and illuminate the face of the subject with a direct burst of light. This technique works, but it tends to flatten the facial features of the subject. My goal was to bring out the personality of my subject, so I chose to use my SB-800 Speedlight as an off-camera remote flash.

My first step was to get a general exposure of the scene's ambient light. The Matrix metering system in my Nikon D2XS made that easy. Adjusting my exposure manually (I like to use manual exposure settings, but aperture- or shutter-priority modes will accomplish similar results), I chose ISO 200, a shutter speed of 1/320 second and an aperture of f/3.5. I did that using the metering scale visible in the viewfinder. Then I took a shot and took a look—at the LCD screen to determine if I liked what I saw. Then I underexposed the scene by 1/3 stop (if you like using either aperture- or shutter-priority modes, the underexposure can be achieved by setting the EV at -0.3).

Now I had a slightly underexposed image of Roberto to which I will added just enough light from my SB-800 to illuminate his face. I set my SB-800 to the i-TTL mode and used the Nikon SU-800 Commander attached to the hot shoe of my D2XS to set the power output and trigger my off-camera remote SB-800. Because I underexposed my scene by 1/3 stop, I had to boost the power of my SB-800 by using a +0.3 output. My camera's white balance was set for slightly warmer than daylight. I also used the warming gel that comes standard with the SB-800 to further warm the image.

Directing the Light
This general setup works very well, but for those times—like this one—when I want to bring out the unique features of my subject's face, I'll attach a LumiQuest snoot to my SB-800 to narrow the spread of light, and then I'll further narrow it to a thin shaft by pinching the end of the snoot with a paper clip. I held the off-camera remote SB-800 in my left hand and positioned it so that the thin shaft of light highlighted only a portion of the face, so in this portrait, the thin shaft of warm light reveals Roberto's eyes as if they were illuminated by the setting sun. This stylized fill flash creates mood as it reveals Roberto's years of living in southern Mexico.

Although Image 2, Sky Kick, is grander in scale and looks quite different, the same basic formula was applied. That is, an underexposed scene and an overpowered output of flash. The photo was taken about 3:00 p.m. and I again achieved my general exposure of the ambient light manually (ISO 100, 1/1250 second at f/4) and then underexposed the scene, this time one stop by increasing my shutter speed to 1/2500 second. I was able to use a shutter sync speed faster than 1/250 by setting my D2X for Auto FP flash mode. Rather than using a warmer-than-daylight white balance as I did with Roberto's image, I chose a cooler white balance of 3600K to add more blue to the sky. This scene required four SB-800 Speedlights set in i-TTL and remote modes to overpower the ambient sunshine and illuminate a larger area. I used warming gels over the front of each SB-800 to counterbalance the cool blue white balance of 3600K and give my soccer player a warm sunset skin tone. This is a very stylized look that works well in the sports and fashion industries. Because I underexposed the scene by one stop, I overpowered my four SB-800 Speedlights, giving each a power output of +2. Why +2 and not plus +1? Because the warming gels slightly diminish the output of light illuminating my subject.

The four SB-800 Speedlights with warming gels easily illuminated my subject with warm sunset light while my cool white balance kept the sky a deep blue.

More Power to You
For Image 3, Home by Sunset, the same basic formula was applied, this time with ISO 200, 1/8 second and f/16. Because the sun had set, I decided to use that slow shutter speed plus rear curtain sync on my D2XS to show the graceful motion of the horse and rider.

The two SB-800 Speedlights I used for this photo were rubber banded together so I could easily hand hold them, and they froze the areas of my subject that were illuminated by their light while the background and second rider became a sweeping pan. I underexposed the scene by one stop to help increase the color saturation in the sky and then set both Speedlights for a power output of +3 to compensate for the warming gels and to reach my lead rider out in the lake. I used a white balance of 7700K and a warming gel on each SB-800 to increase the feeling of sunset on my subject.

How much I underexpose a scene and overpower my flash can vary depending on whether I want just a pinch of light (the photo of Roberto, for example) or a more creative look (the soccer player or the cowboy).

Light can exert the greatest influence on a picture, and I've found that Nikon SB-800 Speedlights are a fantastic way to achieve beautiful, stylized results.

Note: For tips and techniques on lighting and other imaging topics, read Dave's monthly tutorial articles in Workshop at the Ranch and On the Road at his website, www.daveblackphotography.com.