Tuesday, May 29, 2012
How to use high-speed flash sync for creative effects
|This Article Features Photo Zoom|
1. Freeze the action. Like the name implies, high-speed flash photography allows you to use lightning-fast shutter speeds to freeze the action and use fill-flash. When shooting fast action and using flash, photographers had to rely on flash duration to freeze the action. This meant underexposing the existing light 2 stops or more so the flash was the main source illuminating the subject. Flash durations are very fast and can be over 1⁄2000 sec., plenty fast to freeze most action.
But what if you just want to add a little fill-flash to a road biker as he whizzes by you? For this image, you'd have both daylight and flash illuminating the subject, but the daylight would be the primary source. If you shot at 1⁄250 sec., your maximum flash sync speed without HSS or HyperSync, you would get blurry images. But if you enable HSS or HyperSync, you can shoot at 1⁄2000 sec. and freeze the action in the daylight, and add a little fill-flash.
2. Use selective focus. Another benefit of using High Speed Sync or HyperSync is the ability to use wide-open apertures with flash in bright sunlight. Say you're photographing a model in open shade and want to use an aperture of ƒ/2.8 to nicely blur the background. When you establish the correct exposure using ƒ/2.8, you find that 1⁄1000 sec. is the right shutter speed. And since the model is in some shade, you want to add just a touch of flash on her to liven up her skin tones and add a little more contrast. Since you're using high-speed flash, you'll have no problem shooting at 1⁄1000 sec. You may have to double up your speedlights or move your flash head closer to the subject, but you can still shoot at ƒ/2.8 for that nice background bokeh. I really like to use my 85mm ƒ/1.4 lens with flash. Shooting at ƒ/1.4 almost always means I need to use a shutter speed faster than my normal sync speed of 1⁄250 sec.
3. Darken the background. When I shoot outdoor portraits, I generally like to underexpose the daylight by 1 to 2 stops. Underexposing the daylight produces darker backgrounds with more drama and better separation for my subject. Occasionally, I'll underexpose midday skies 3 stops for a nighttime effect. But to darken the sky this much, I need more than just a small aperture to get this effect. Since I can use flash at any shutter speed, I'll shoot at 1⁄2000 sec. or faster along with a small aperture to ensure I have a dark background. Try underexposing a subject 2 stops against a blue sky; the effect looks dramatic.
PUTTING IT ALL TOGETHER
No matter if you use a single speedlight or multiple large flash packs, high-speed flash photography will expand your creative possibilities. The next time you need to freeze the action with fill-flash or shoot wide open midday, use high-speed flash to solve the problem. Join the flash revolution!
Tom Bol is a freelance editorial and commercial photographer based in Colorado. To see more of his work, visit his website at www.tombolphoto.com.
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