Missing Pages: Flash Modes
The Missing Pages column is a collection of all of the information that should have been included in your camera’s Owner’s Manual—but somehow got left out. This is a hybrid assortment of short articles that delivers the know-how you need to derive the maximum enjoyment—and creative expression—from your equipment.
It’s sort of a juiced-up User Guide for creative people who are not necessarily technical. Each part will teach you how to use one of the camera features or functions that you previously ignored or left set on Auto. And each will include a Creative Project so that you can try some scripted experimentation.
We will explain complex technical subject matter a way that everyone can understand. And if you happen to be a technical expert yourself, we’re including “Nerds Only” sidebars just for you. That way you can dig in deep—or just straddle the edges—of the technological stuff. It’s your decision.
Installment VIII: Flash Modes
Definition: Preset combination of exposure settings that determine whether or not a built-in flash will fire and if it does, how it will synchronize with the camera’s shutter mechanism and other camera parameters.
The little flash that’s built into or pops up from your camera is simple, right? When it’s too dark it fires, and when it’s bright it keeps its head down and minds its own business.
The flash itself is a marvelously simple invention. It consists of a flash tube, which is just a bulb that’s capable of becoming very bright for a very brief period of time (as short as 1/50,000th of a second), a battery and a capacitor to store the energy needed to make the bulb get bright. The term “recycle time” refers to how long it takes for the capacitor to “form” (i.e., accumulate enough energy from the battery so that it can intensely power the flash again). The “flash synch speed” is the maximum shutter speed that a camera can set when the flash is active. This differs widely from camera to camera. Some cameras have a “hot shoe”, which provides both a secure attachment point and an electrical contact for synchronization.
An Electronic Flash Unit (as the shoe-mounted version is known in the trade) as well as your camera’s built-in flash is remarkable because in many ways a flash is like a jar full of lighting (the spark, not the beverage). Correct exposure depends on controlling it, and that’s not an easy thing to do. The intensity of the flash is controlled by adjusting the duration. But it’s not as easy as is sounds. So camera manufacturers, over the years, have contrived ways to tame the lighting so that you’ll get more pleasant results. This collection of controls is called Flash Modes.
Okay, it may seem logical to presume that when the flash is “not on” it’s “off” but that’s a faulty assumption. The Off or Forced Off (Panasonic calls it “Suppressed”) Mode means that the flash cannot fire. This is an important distinction because many (if not most) of today’s cameras will turn the flash on automatically when needed, even if you are not particularly expecting it.
Ah—here’s the culprit to blame for the mayhem in the paragraph above. In the Auto Flash mode the flash remains dormant until the camera decides it’s time to put a little light on the subject, at which point it signals the flash to move into position and commence firing.
As the name implies, in this mode the flash will fire whether it wants to or not. I often tell beginners to think backwards and turn their flash ON outside and OFF indoors. That exposes them to the benefits of both Fill-in Flash outdoors and Available Light inside. Forcing the flash to fire outside, even when there’s plenty of light, will brighten colors and wash away shadows, especially those that make human faces look more like masks. Forced On flash also saves your bacon when shooting a backlit subject.
Not all (in fact, not many) cameras have this feature as a separate mode; instead it’s usually incorporated into the Forced On mode. But it’s worth mentioning because of the concept behind it. The primary light source is ambient light—the flash merely fills in the shadows.
Aside from zombies, glowing red eyes are never flattering. Light from the flash reflects directly off the retina at the back of the eyeball, and if the flash source is too close to the lens axis, the result is a lifeless red blaze. As a countermeasure, cameras use various techniques to cause the pupil to contract, thus reducing the problem. Some use a pre-flash—a softer flash that fires a millisecond before the real flash. Some use a bright LED that temporarily blinds your subject. Some cameras have built-in Red-eye Correction that restores natural color AFTER the image has been captured. It’s not a Flash Mode, but it’s usually more effective than pre-flash. You can also remove Red-eye in Photoshop.
Second Curtain (or Rear Curtain) Synch
The shutter is not simply a window that opens and closes. Often it’s more of a moving slit; that is, the first curtain opens and is still traveling when the second curtain begins to follow it. Normally, the flash fires as soon as the shutter opens. When set to Second Curtain (or Rear Curtain) Synch the flash goes off just before the shutter closes, which affords enough time for ambient light to impact the exposure. Use this mode to capture mood lighting or to show the natural lights that appear in the background behind your subject.
Flash bracketing is the same as regular exposure bracketing, except that that flash is the illumination source. This is an underused feature partly because few cameras implement it well except at very close range (despite what their instruction books claim). For rapid-fire Flash Bracketing the flash must be able to recycle very quickly—almost instantaneously. Play with it and use it if you can.
Turn your flash OFF indoors and ON outside. That’s right—the opposite of what you’ve thought (or been taught) all these years. You’ll see a positive difference in your photos right away. Some will turn out positively awful, but more will be greatly improved. As you practice this exercise you will learn which situations benefit from Flash ON and which from Flash OFF.
Cycle through the various Flash Modes; here’s how. Find a suitable subject, indoors in relatively dim light. Humans work well (zombies are okay too, for the Red-eye portion) as do other mammals. Try your best to keep the distance the same and, of course, don’t change the ISO or zoom. Shoot one or two images using each of the various Flash Modes. Compare the results and decide which yielded the best image.
Bounce your flash—no, no, don’t throw it!—deflect the light toward the ceiling by taping a business card at a 45-degree angle in front of the flash tube. If you’re using an accessory flash that has bounce capability you probably won’t learn anything new from this assignment. Make sure you are shooting where there is a standard height (8-foot) ceiling so that enough light will be reflected down on your subject. This technique works great for portraits. Also try rotating the camera 90-degrees and bouncing the flash off of flat, white wall. (Note that if the ceiling or wall has a strong color it will tint the resultant image.)
For Nerds Only: Strobes and Slaves
Some of the old-timers down at the camera shop may call them “strobes” but, strictly speaking, they’re not. Strobes blast a string sequence of psychedelic flashes whereas a Flash emits just one powerful blast.
Slave Units are self-contained accessory flashes that fire when activated by another flash. They have a light sensitive sensor that triggers ignition when hit by the sudden burst of a flash. Since the camera’s Flash Synch Speed is typically a slow 1/250 of a second and the Flash Duration a speedy 1/30,000 or so, there is plenty of time for one flash to fire and set off a second while the shutter is open. After all, this is happening at the speed of light, and that’s as fast as it gets.
Text ©2009 Jon Sienkiewicz.
Text ©2009 Jon Sienkiewicz.