Flashes

All point-and-shoot cameras and a lot of consumer SLR’s have built-in flashes now. So why would you want to buy an off-camera flash? Everyone has experienced the dreaded “redeye” in their people photos. And the truth is, no “redeye reduction” system really gets rid of redeye. The only real solution to this problem is moving the flash away from the camera. Off-camera flashes are also more powerful and most give you more control over how you light your subject.

Flash Features

Guide number  - Usually quoted in feet or meters at 100 ISO. This number tells you what distance your flash can cover with ISO 100 film, at a particular aperture. A higher guide number = a more powerful flash.

Flash exposure modes - High-end flashes usually have a TTL mode that lets the flash read the amount of light it’s putting out at the film-plane. When it’s put out enough light to expose the subject correctly it shuts off. Other modes are manual and strobe. Manual allows you to set the power-output of the flash yourself so you don’t have to rely on the camera’s automatic metering. Strobe will flash multiple times during an exposure for flash-sequence photography.

Zoom – A lot of current flashes will zoom to match the focal length of your lens. The most common flash zoom is 28-80mm. And some flashes also have a pullout diffuser for 18 or 20mm focal lengths.

Tilt and Swivel – The ability to tilt and swivel the flash head lets you bounce the flash off walls or ceilings. Photographers bounce flash to create shadows and/or soften the harsh effect flash light can often have.

Second-Curtain Synch – Normally a flash will fire at the beginning of an exposure. Flash used with slow shutter speeds can have a strange effect when you photograph objects in motion. It will make a trail in front of the subject, instead of behind. Second-curtain synch makes your flash fire at the end of the exposure so the exposure trails behind the subject. Some high-end SLR’s have second-curtain synch as a camera option so you may not need it as a flash option.

Slaves – A slave is a flash that is triggered by another flash. Slaves are usually non-dedicated units, or accessories that you attach to your flash. But some flashes have built-in slave or wireless functions that will allow you to run multiple flashes from one location.

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