When a Good Flash Goes Bad
Because flash is too brief for us to see how the illumination will look in the photograph, it's easy to take bad flash pictures.
When the flash is much more powerful than the ambient light, backgrounds go dark. Mess up an exposure calculation, and subjects nearest the lens are blown out (overexposed). Strange reflections creep into shots when you least expect them. Of course, with today's digital technology, you will be able to review and re-shoot if necessary.
The ultimate solution to bad flash pictures is to just keep taking them. Practice means everything with flash photography. With time and experience, you'll soon learn what works and what doesn't. You'll hone your techniques and figure out how to move your flash around or adjust its settings to take better advantage of what it can do.
In the meantime, here are some suggestions for troubleshooting some of the most common problems that erupt with flash photography.
Bad Reflections
Flash travels in a straight line in all directions and bounces off objects, walls, mirrors, and windows. If you're shooting a subject in front of or through a window, remember that you must move up, down, right, or left until the flash doesn't reflect back into the camera.
If you can set off your flash without taking a picture, look through the viewfinder and pop a flash. If you're shooting digital, you probably won't care if you waste a shot. In any case, watch for reflections in windows, glasses, framed pictures, and even glossy paint.
Generally, you can avoid these sorts of reflections by not photographing straight into a wall or reflective surface. Set your subject up so that you are shooting at a 30°–45° angle to any reflective surface.
If you absolutely have to be directly in front of a window, try lowering the camera to see if you can get the subject to block the reflection. When two mirrored or shiny walls meet at a right angle, they will always reflect directly back to the camera, no matter what angle you select.
Glasses and Flashes
Some people wear eyeglasses with special non-reflective coatings. However, if the person you're photographing wears the old-fashioned reflective type of lenses, try the following:
Lowering or turning the subject's head until the reflection disappears
Raising the arms of the glasses, which will tilt the lenses down without the subject having to drop her chin
Taking the glasses off
You can prevent some conflicts by making sure glasses are pushed all the way on so the top rim doesn't cast a shadow on the eyes. After you pose your subject, set off a test flash while you look through the viewfinder for objectionable reflections. This may take a few tries if you're shooting multiple subjects wearing glasses.
A flash unit with properly charged batteries should be ready to go fairly quickly after you turn it on. If yours doesn't perform properly, try cleaning the contacts on the batteries and the flash. If they're dirty or corroded, they can affect performance.
Incorrect Exposures
Automatic cameras that sense the flash coming back from the subject can be fooled by subjects that are very light or very dark.
This cannot always be prevented, but one simple trick will give you a better chance of getting it right: Eliminate any large gaps between your subjects if you're using an automatic flash. The sensor might be aimed at the empty space between your subjects.
If that's so, the sensor will tell the flash to stay on until that faraway empty space is properly exposed, baking (overexposing) your intended subjects in the process.
However, if you try to block the gap by putting your subjects against a wall, you'll get dark shadows behind them, courtesy of your flash. No matter how high or low you place the camera there will always be a shadow behind the subject that the camera will probably pick up. This is a good reason to use a slow enough shutter speed to allow the ambient light to fill in the objectionable shadow.
Weak Lighting/Flash Falls Off
Automatic flashes work best over a certain range that varies depending on the speed of film, the largest aperture of the lens, and the power of the flash.
The reason many flash pictures don't work is because the photographer underpowered the flash. He selected the wrong combination of film speed, aperture, and power for a great distance. To double the effective power or distance, get a film that is four times as fast. Changing from ISO 200 to ISO 800 doubles the distance at which your flash will work.
The light from your flash diminishes (falls off) as it travels away from your flash. This means that a point far from the flash will get less light than a point near the flash.
If a subject is beyond your flash's range, chances are you won't see it at all in the picture. The best way to avoid these shots is to know what your flash's effective range is and stay in it.
If you know your flash is too weak for a certain situation and you can't move it closer, try using a slower shutter speed to allow more ambient light to enter your lens.
