Dave Black: 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.