By Robert Correll

Part of Digital SLR Photography All-in-One For Dummies Cheat Sheet

Your digital SLR camera may have several different flash options. Each of these options is useful in different lighting and motion situations:

  • Auto TTL: Automatic flash mode. The camera and flash determine the flash strength. TTL stands for “through the lens,” which is how the flash assesses the scene to determine exposure and distance information, if possible.

  • Red-Eye Reduction: Fires a series of pre-flashes to constrict people’s pupils, diminishing the chances of red-eye.

  • Fill flash: Forces the flash to fire in conditions when it is not necessary (from an overall exposure standpoint) in order to eliminate shadows and balance the light. Use fill flash outdoors to keep people’s faces from being in shadow. Use indoors to balance bright light from windows.

  • Slow sync: Slows the shutter and flash down to increase the amount of ambient light that contributes to the photo. The result is brighter backgrounds. You may have to raise ISO to keep shutter speed fast enough for handheld photography.

  • High speed sync: A special flash mode used when you have an external flash mounted on your camera’s hot shoe. This mode enables much faster shutter speeds than are possible with pop-up flashes. Use for action shots or in bright light when you need a very fast shutter.

  • Rear curtain: Waits to fire the flash until just before the exposure ends.

  • Repeating flash: Divides the flash up into a number of discrete pulses, triggering them over the length of the exposure.

  • Wireless: Enables wireless mode on compatible flashes and camera bodies. When properly configured, syncs the off-camera flash with your camera, enabling you to trigger the off-camera flash remotely.

  • Manual: The flash mode that requires you to set the flash strength yourself.