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Tuesday, June 22, 2010

Copying Copyright


Protective Symbols • Turned Off With Tripods • Hold Still...1, 2, 3...HDR! • Old Flash, New Digital

Labels: How-ToColumnTech Tips
Hold Still…1, 2, 3…HDR!
Q The tip you gave at a recent seminar about putting the camera in burst mode to capture bracketed images was a revelation! I’d appreciate a review of the precise technique.
C. Wiley
Via the Internet


A When capturing images you intend to composite, as in blending a range of exposures to control contrast or for creative effect (a technique called HDR, or High Dynamic Range), it’s always best to use a tripod. The ideal capture process for HDR images is to take at least three exposures, one for the light areas, one for the middle tones and one for the dark areas. When composited in HDR software such as Photomatix or Photoshop CS3-5, the optimum exposure is used for each area of your image. So, for example, skies or clouds are bright without being blown out, middle tones are well defined, and shadow areas have excellent detail without noise. Since you’re matching up precisely three different captures, it’s important to use a tripod.

But sometimes you can’t. The next best thing is the rapid-capture method. Evaluate the contrast areas in the scene and determine the base exposure for the middle tones. Set your camera for auto-exposure bracketing for a series of three shots. Calculate your three exposures at one stop over the base exposure, one right on the exposure and one at one stop underexposed. If the scene is very contrasty, use one-and-a-half- to two-stop intervals. Set your camera at its fastest capture rate. The result is that the three exposures are recorded in a single burst, minimizing the potential for movement from one capture to the next. Still, you must be careful to employ optimal handholding technique, including bracing against a stable platform, keeping elbows into the body, supporting a longer lens, squeezing (rather than torquing) the shutter release, etc.

Fine print: This offer is null and void if the subject is moving during the capture sequence or at shutter speeds longer than about 1⁄15 second with image stabilization. You need three sharp, matched images to make this work.

Old Flash, New Digital
Q I’ve recently converted from film to digital, and I’ve heard that flash units that I used with my film SLRs may damage my Nikon D60 DSLR. I’d like to use flash for close-up photos of flowers and other indoor shots, but the built-in flash on my D60 isn’t powerful enough alone. Do I need to buy a new flash?
J. Clark
Via the Internet


A It’s not a good idea to use an old SLR flash unit designed for film cameras on the hot shoe of your new DSLR. The trigger voltage of the older flashes can be in the hundreds of volts. The flashes for many new DSLRs typically have a trigger voltage of 12 volts (for example, Canon works on six volts). So, yes, you should buy a new flash for use on your D60 to take advantage of all of the automatic features of which the new flashes are capable. That said, an option that allows you to use your old flash in manual mode is Safe Sync from Wein Photo Products, an accessory that goes between your camera’s hot shoe and the flash; it reduces the trigger voltage to six volts, making the older film SLR flash unit safe for any digital SLR.

But don’t throw away your old flash! Its useful life may be extended in an important way, using wireless flash technology. Take the old flash off your camera, mount it to a wireless slave (Wein makes these also), place it in the optimum location to light your subject, and set the built-in flash on your camera to fire the off-camera flash. You can do this with as many old or new flashes as you want or need. If your old flashes have manual power settings, you can change your lighting setup easily by adjusting the strength of the output of each flash.

For information about upcoming seminars and digital-imaging workshops, visit www.georgelepp.com. If you have any tips or questions, address them to: OUTDOOR PHOTOGRAPHER, Dept. TT, George Lepp, 12121 Wilshire Blvd., Suite 1200, Los Angeles, CA 90025-1176 or online at www.georgelepp.com.

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