I can understand their apprehension, even skepticism, when I say this. Light from flash units whether camera-mounted or off-camera can be harsh, unpredictable and totally unnatural-looking. All you have to do is look at your average driver's license or passport picture to see how garish this light can be.
But when used correctly, especially with judiciously chosen shutter speeds, flash can become a wonderful tool to improve your photographs.
The three images I've selected here, of a young furniture restorer in Venice, are from a recent portrait session and show how light from even a single flash unit can dramatically alter a picture. The first photograph was made without any flash at all. The only light comes from the window on the right and from a bright, downward-pointing halogen light in the ceiling near the wall. Often, especially when I shoot Polaroid tests, I will make a "baseline" available light picture to see the effect of any light that I will add to a scene.
Obviously in this case I needed some fill flash on the young woman. But how much?
The second picture does a great job of illuminating the subject, but that's about all. Gone is any subtlety. The girl becomes totally separate from her surroundings, brightly lit by a too-powerful flash. Note not only how the subject is hit in the face with the light but how the flash also obliterates any shadow on the back wall. This double-whammy weakens the picture by robbing it of detail and depth. (In addition, this particular exposure blows out detail in the window, further flattening the image.)
The final image, in which the flash output has been lowered (and the camera shutter speed increased), creates a pleasant, natural-looking balance among the three sources of light in the picture the flash, the halogen downlight, and the natural light coming through the window. I should add that each of these photographs is a straight print, with no additional dodging or burning in.
Though lit by flash, the woman's face in #3 remains in pale, natural-looking shadow. Nevertheless, compared to photo #1, made only by available light, the effect of the flash is profound. But see too how this much more subdued flash output does not overpower the halo-like shadow of the ceiling downlight, creating an interesting pattern on the back wall, nearly identical to that in the available light shot.
Finally, a higher shutter speed lets more detail in the courtyard beyond the window show through, adding depth and context to the image.
But how to modify the light from your flash?
Flash can be modified in several ways. First, the output, or brightness, of the light can be regulated. Second, the quality of that light can be changed, most often by changing the light's direction or shining it through a diffusion medium.
In this case, I first diffused the light coming from the flash. Then, when I determined the light still was too dominant, I lowered the output of the flash unit.
Diffusing light from any flash unit is comparatively simple, especially with small units like the Vivitar 283, which is what I used here. The simplest method is to place a few layers of white handkerchief over the flash head. A more sophisticated way to achieve the same end is to place a plastic diffusion head over the unit. The one I always carry with me is made by Sto-Fen and it snaps right onto the 283.
But arguably the simplest way to modify light from a flash unit is with a bounce card.
All but the simplest and cheapest flash units have swivel heads that allow you to point the business end of the flash either directly at your subject, or straight up in the air, or somewhere in between. (More sophisticated units, like some of the higher-end Nikon SB strobes, let the flash head swivel from right to left as well.)
With the flash head pointing either straight up in the air, or at a slight upward angle, a white card secured to the back of the unit will direct light toward your subject in a much more pleasing fashion. If you think of light as you would a stream of water, envision the difference between being hit in the face with a direct stream of water from a garden hose (i.e., direct flash) versus being showered by a gently rain with the hose pointed toward the ceiling.
This method also eliminates harsh shadows from the flash and looks much more natural.
But even the most diffused and flattering light from a flash can lose its effect if it is too bright. And, in fact, that is what is happening in photo #2. My flash is just as diffused as it is in the final picture, but the brightness of the scene is unacceptable.
What to do?
Enter the Vari-Power Adapter.
This little accessory, made by Vivitar for its portable strobes, is invaluable because it lets you manually power your strobes down or up in almost infinite variations without changing the flash-to-subject distance yet another factor that can change the quality of the light and add another troublesome variable to the equation. In fact, without this module, my 283 would just be another little flash unit, of comparatively limited use for specialized shooting. The Vari-Power module plugs into the front of the unit, replacing the Auto Thyristor that regulates flash output according to its own built-in rules relating to flash-to-subject distance. What makes the Vari-Power so useful is that you, not the thyristor's "electric eye," determine the brightness of the flash. Good though the thyristor may be (and we rely on it whenever we shoot weddings and events), it always is programmed to provide "adequate" flash power. When, in a case like the one we are seeing here, all you want is a kiss of light, the Vari-Power Adapter is a must.
Inevitably, when I talk flash, the question arises, "But how do I determine the correct exposure?" As with almost everything, there is a cheap answer and there is an expensive answer.
The cheap answer is simply to use the table on your flash unit, usually based on your flash unit's guide number, to figure your working aperture, which then is used in conjunction with a shutter speed that is within your camera's sync range, usually 1/250 of a second or slower. This most often is based on the formula of dividing the guide number by the flash-to-subject distance to arrive at the correct aperture (e.g., guide number of 100 divided by a 10-foot distance equals 10, or a working aperture between f. 8 and f.11).
The expensive answer is to gulp and spend several hundred dollars on a flash meter, which will do the calculations for you instantly and unerringly.
More than a decade ago, I spent nearly $500 on my Minolta Flash Meter IV; then another half-grand on a Minolta Spot Meter, that also has flash-meter capability.
I use them all the time and I love them. I've never regretted buying them.
Frank Van Riper is a Washington-based commercial and documentary photographer and author. His latest book is Down East Maine/A World Apart (Down East Books). He can be reached at firstname.lastname@example.org.