Thursday, March 5, 2009

Control flash for snappier images

Many people think the hallmark of “amateur” photography is on-camera flash, with blown out faces, dark backgrounds and red eye. In low light, most modern cameras will pop that little sucker up and give you that “special” quality your mother (or grandmother!) achieved with her Instamatic camera equipped with its flash bar or flash cube. It’s not uncommon for an aspiring photographer to set his camera so that the flash will not fire at all, in an attempt to achieve more “professional” results. What they often achieve is rather dull and flat. Just because it’s a dinky little pop-up feature doesn’t mean your camera’s flash can’t help you achieve some amazing results and add sparkle to those dull images.

On page 106, my camera’s owner’s manual describes “Flash Exposure Compensation.” If you learn this technique, I guarantee you will improve the quality of your candid photography. Here’s why. Any scene has a certain amount of light available in a range of what’s called exposure values (EV). This is a way of describing the range from the brightest to the dimmest illumination in the scene you’re photographing. In the picture below, on the left, part of my model’s face and the top of her hand has bright light from direct overhead sun. Her hand shades her face – especially her eyes. The difference between these two levels of light is somewhere between four and five stops of light.

Your camera can correctly expose for either extreme, whether very bright or very dim. But when you try to capture both in one image, you’ll either blow out your highlights trying to capture the shadows, or you’ll lose detail in the shadows trying to capture the bright areas.

On my camera, a Canon 30D, if I press the flash button near the pop-up flash, my flash will fire, no matter how much light there is in the scene. In other words, even in bright sunlight, when the automatic settings would not ordinarily cause the flash to fire, I can make it fire. This is called fill flash. But how much is too much, and how much is too little? Because this is a manual flash mode, there is no flash metering. The image exposure is actually metered off the ambient light, as if there were no flash. And the flash has a set amount of power, so it could be way too bright or not bright enough.

My owner’s manual shows me the button on the top of my camera that lets me control the level of light the flash applies. By default, it’s set in the middle of a range of plus or minus two stops. Using my Quick Control Dial (a wheel on the back of my camera), I can adjust the level of the flash in 1/3 steps through this two stop range. The dial will show me how much or how little I’ve changed the flash power. It will only take a couple of test shots at the most to adjust the amount of flash to balance out the lighting of the scene; that is, to fill in the shadows.
Unless you shoot with a Canon 30D, your camera’s controls will operate differently. But most modern DSLR cameras, for sure, and some point and shoot models, will provide this capability. Read the section of your owner’s manual that covers your built-in flash. It may be called, simply, fill flash. But the manual should tell you how to control the amount of light your flash puts out

Using flash compensation, the picture on the right shows my model’s face in the same setting with the same amount of sunlight and the same basic exposure—f/14 at 1/100 sec and ISO 100—but the fill flash provided light in the shadows and also put a “catch light” in her eyes. I encourage you to experiment with this technique. When you’re in a brightly lit place, like outdoors in bright sun, or if you’re indoors in a relatively dim room, you can set your camera’s regular exposure for the ambient light and then provide a balanced amount of light from your built-in (or external) flash that will make your images snap. Professional photographers have a number of tools in their toolbags. This is one of the most versatile. Using it will help you achieve professional-quality results.


Bruce said...

That is really interesting information. As a total amateur (<$200 digital camera), I agree with the thoughts on flash = amateur and no flash = pro.

Your contrast shot here really shows the value!

Jack Allred said...

Hey, buddy. You can get a lot more camera for not much more than the $200 you've invested so far. As much as you travel, might be a good purchase. Then we might see fewer iPhone pics on FB, eh?