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Monday, October 1, 2007

Daylight Fill-Flash


Sometimes changing the exposure just isn't enough to get the shot

Daylight fill-flash
With fill flash.

An accessory flash may not come to mind initially as an important tool for wildlife photography, but I never go out on a shoot without one. I recommend that you pack a flash in your gear bag before you next venture into the field.

Outdoors, a flash can be used for what’s called daylight fill-in flash photography. When an animal is backlit, a flash can fill in the strong shadow that obscures the animal’s face if the subject is within the flash’s range.

These two pictures of a saw-whet owl illustrate the value of using daylight fill-in flash. In this situation, I could have used my camera’s spot meter and set the exposure for the owl, but the sky would have been way overexposed. Therefore, daylight fill-in flash was the way to go.

To do this properly, you need an accessory flash with variable flash output control—that is, plus or minus flash exposure compensation. Accessory flashes are much more powerful than a camera’s built-in flash.

First, set your camera to the Manual exposure mode. Turn off your flash. While in the Manual mode, set the exposure for the existing light conditions. Take a shot, and check your camera’s LCD monitor to make sure you have a good overall exposure of the background. You also may want to check the histogram to see if either side is abruptly cut off. That means details aren't being recorded, and this is something you can't always see on the LCD.

Using a fill-flash can be an invaluable tool when photographing wildlife. To capture images of birds like this saw-whet owl, you’ll likely use a zoom lens and may need to extend the range of your flash by attaching a flash extender or by increasing your camera’s ISO. Canon EOS-1Ds Mark II, Canon EF 100-400mm IS USM, Canon 580EX Speedlite.


Next, turn your flash back on and take a picture with the flash set at -1 1/3 (just a recommended starting point). If your picture on the camera's LCD monitor looks too much like a flash shot, reduce the flash output to -1 2/3. If it’s still too "flashy" continue to reduce the flash strength in one-third increments until you’re pleased with the results.

If the subject is too dark at the starting point of -1 1/3, increase the flash output to, say, -1. If your picture is still too dark, increase the flash exposure until you're pleased with the results.

This technique works because even in the Manual mode, the flash operates in the TTL (through the lens) Automatic flash metering mode.

Daylight fill-flash
Without fill flash.

Some newer D-SLRs and flash units help the flash metering system determine the main subject’s distance and actually do the aforementioned settings automatically in the automatic modes (Program, Aperture Priority and Shutter Priority). Still, I suggest you master the recommended flash technique if you're serious about your photography.

You can extend the flash range by attaching a flash extender to your flash (I use the Better Beamer). You also can extend the range by increasing the ISO settings. As you increase the ISO setting, your camera’s image sensor becomes more sensitive to light. So, in effect, the light from the flash travels farther.

Sure, you could always decide to go without a fill-flash and try to open up the shadows in your editing program, but that works only to a degree. The more you open up a shadow, the more digital noise you’ll see in those shadow areas. You also may see a real lack of detail. Remember, the image sensor can only capture a certain range of exposure, from light to dark. Go past that in either direction, and you’ll have problems.

Always strive for the best possible in-camera pictures, which sometimes call for daytime fill-flash. That way, you can spend more time outdoors taking pictures—and having fun with your photography—and less time in your digital darkroom.

Rick Sammon
has published 27 books. Visit ricksammon.com for more information. Meet Rick at one of the Outdoor Photographer/PCPhoto workshops.


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