16 flash terms you should know

When your camera's built-in flash isn't enough, here's what you need to know about adding more

If you want to graduate from snapshots to great shots, an external flash unit will significantly improve your pictures. Here are terms that will help you become a strobist.

Shown: Canon Speedlite 580 EX II

Shown: Nikon Speedlight SB-600

Virtually all digital cameras and most film cameras have a built-in flash. That flash is satisfactory for snapshots of the family and such. It probably has several modes, including fill flash, red-eye reduction and night portrait. You may or may not have tried all of the settings. But if you want to graduate from snapshots to great shots, an external flash unit will significantly improve your pictures.

If you're going to add an electronic flash unit to your gadget bag, there are a few terms you need to know. We've narrowed it down to 16 items. Rest assured that the great majority of all flash operations are automatic. If you have the right equipment and set it to the right mode you'll have little to worry about. And as you get comfortable, you can take even greater control over your flash by using its more advanced light-controlling features.

To take advantage of external flash, you will most likely need a camera with a Hot Shoe. All SLRs--digital and otherwise--have one. Most compact cameras don't, but a handful of high-end ones do. Check the specs, or just look at your camera. If you own a camera that lacks a hot shoe, you can still add off-camera flash (albeit limited) by buying an inexpensive slave unit (see our Slave Flash buying guide for more information about this).

You need an external flash if...

  • Your subjects often have red-eye
  • Your subjects are too dark when shot with your camera's built-in flash
  • The harsh light and annoying shadows behind your subjects bothers you
  • It takes a long time for your camera's flash to recharge between shots
  • You want to change your flash's brightness
  • You want to change the background brightness/darkness independent of your flash settings
  • You want to hold your flash away from your camera to eliminate shadows

Bounce Flash
This is what you get when the flash is directed toward the ceiling, a wall, or other neutral, reflective surface so that the subject is illuminated by the light bouncing off the walls. A Bounce Flash has a head that swivels so that it can point in different directions. This technique provides very even illumination and minimizes shadows and red-eye.

Use bounce flash for portraits, close-ups, and, well, just about everything. The flash must be fairly powerful, but even so, make sure that the ceiling is not too high or the light will never make it back down. Also keep in mind that walls or ceilings that have strong colors will tint the resultant image. As you can see – this is a very useful feature – and it’s something that the small flash that’s built into your camera cannot do.

Two different definitions: As a noun, a Bracket is an L-shaped metal frame that attaches to the bottom of the camera and provides a perch for the flash to sit on.

As a verb, to Bracket means to shoot a series of images at settings that result in slight underexposure, normal (right on) exposure and slight overexposure in fixed increments. Later, you can select the best exposure from the series of images and discard the rest. Some cameras allow automatic Flash Bracketing as described. To accomplish this, the flash must be capable of fast recycle.

A Dedicated Flash has a foot that is designed to mount atop only one brand of camera which, of course, has a matching shoe. The advantage is that manufacturers can add a number of specialized electrical contacts that enable advanced functions. The flash communicates with the camera via the contacts. It can also make the connection more secure. The disadvantage comes into play if you own more than one brand of camera – there’s no compatibility across brands.

A semi-translucent, textured section of plastic that attaches over the flash and causes the light to spread out in a wider angle. It can be used to soften a harsh flash, reduce flash intensity (for close-ups shots, etc.) and to match the coverage of wide-angle lenses. They are sometimes available in bold colors for special effects.

Fill Flash
Taking photos in strong sunlight or backlight can cause dark shadows to appear on the subject’s face. Fill Flash works in concert with ambient light and eliminates these shadows without causing overexposure. It also adds some snap to the colors and tends to improve the overall quality of the image. This is the single most potent technique a new photographer can learn. Most compact digital cameras have a Fill Flash Mode. Onboard flash generally only provides enough light to work as a fill flash on head-and-shoulders portraits.

Flash Meter
A handheld light meter that measures the output of electronic flash units. Most commonly used in a studio or other indoor situations, these devices are generally capable of measuring ambient light as well. They take the guesswork out of flash exposure settings and are indispensable when shooting indoor portraits, especially with multiple flash units, or a combination of ambient plus flash. (Pictured: Sekonic L-308S Flashmate)

Guide Number
The Guide Number (GN) is the f/stop (aperture) number you use to produce proper flash exposure of a subject 10 feet away, multiplied times 10, and that ISO is set to 100. So, if your built-in flash has a Guide Number of 14, you would have to shoot at f/1.4 if your subject was ten feet away. In the days before automatic flash it was actually necessary to do the math and measurements. Now, the GN simply indicates the relative strength of the flash unit.

Hot Shoe
A shoe is a stamp-sized, rectangular interface on a camera to which a flash is mounted. A Hot Shoe also provides an electronic interface in addition to a physical one. The flash communicates with the camera via the hot shoe and thereby fires at the proper time, a procedure that is sometimes referred to as Flash Synchronization. (Pictured: Hot Shoe from Canon Digital Rebel XTi)

NiMH is the abbreviation for Nickel Metal Hydride, a battery technology that is commonly used in rechargeable cells. NiMH batteries are very efficient, inexpensive, and provide substantially longer service life than alkaline batteries. If you own a flash unit that uses AA-size (penlight) batteries you’ll save money by switching to rechargeable NiMH cells.

PC Terminal
The physical interface where a flash cable can be connected to a camera. It resembles a small circle within a circle. Long before the Personal Computer existed the term PC Terminal came into the photographer’s lexicon. At that time, shutters were built into lenses instead of cameras, and different styles of shutters required different flash connections. PC describes a flash interface that is compatible with a Prontor-Compur type shutter. This has since become more-or-less a universal standard, although PC terminals usually aren’t found on entry-level DSLRs. (Pictured: PC terminal from Canon EOS 30D)

The time it takes for a flash to rejuvenate after firing. To operate, a flash unit draws electrical energy from a battery, stores it in a capacitor, and when triggered, discharges the energy into the flash tube. It takes a few seconds for that process to Recycle before the flash can be fired again. Short recycle times obviously mean you can shoot more often without delay. If you shoot before your flash finishes recycling (usually indicated by a red light that goes on in back of the flash), the flash may not produce enough light, and your pictures would be too dark. (Pictured: Ready Light from a Nikon SB600 flash)

Red-Eye Reduction
When a flash is fired directly at a person, the light reflected from the back of their eyeballs causes their pupils to appear red. (If the subject is a dog or deer, their eyes may appear green, blue, or yellow.) The condition is worse if the flash is positioned very close to the linear axis of the lens or too close to the subject, or when the subject’s pupil is dilated. Red-eye is common in compact cameras because the flash is usually less than an inch from the lens.

Red-Eye Reduction is a feature that reduces the reddened appearance by causing the subject’s pupil to constrict – usually by firing a low-powered pre-flash pulse. It removes the zombies from your snapshots. A shoe-mounted flash is usually separated far enough from the lens that it won’t produce red-eye.

Baby before (left) and after (right) red-eye reduction was used.

A circular flash that is attached surrounding the front of a lens. It produces very even, shadow-free lighting and is often used for macro and close-up photography. Your dentist probably owns one.

This is an old fashioned term for an electronic flash. Although it is technically incorrect, it’s still commonly used. A true Strobe is a device that produces a series of flashes at a controllable interval. It’s used to create a sequence of overlapping still images and presents a “stroboscopic” effect that resembles a badly edited movie. (See Jim Bailey’s article on stroboscopic effects.)

Synch Cord
A cable that is used to attach a flash to a camera. “Synch” is the abbreviation for “synchronization.” It’s sometimes written “synchro” or “sync.” (Pictured: PC end of a synch chord)

TTL Flash
TTL is an abbreviation for Through The Lens. It indicates that the camera is making the flash exposure settings based on the amount of light that is actually entering the lens during the exposure process. This yields consistently accurate flash exposures.

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