Do You Know Your SBA?; The “Shake Begins At” Level And Image Quality Page 2

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My SBA with a Canon EOS 5D Mark II outfitted with a 24-105mm IS Canon lens zoomed out to 105mm is 1⁄13 sec. I know because I shot a series of images at descending shutter speeds and cropped each to a thumbnail that represented about 1 percent of the total pixels. The 5D Mark II was set to produce a JPEG 5616x3744 for a total of 21,026,304 pixels. The crops I studied were a hair larger than 200,000 pixels (e.g., 450x450). I studied the crops at 200, 400, and 600 percent of actual size and arrived at my subjective conclusion.

Yes, even though I tried to be as scientific as possible, my appraisal is still subjective. Yours will be, too. To be fair, parts of the images shot at 1⁄10 sec were pretty damn good, all things considered. But my personal standards rejected them, and that’s how subjectivity comes into play. You could get very different results if you performed the exercise even if you used the exact same equipment.

And it’s very important to note that I did not evaluate an extensive list of camera and lens combinations. Compared to what’s available, my sample size is very tiny. So let it be said that this test is to show directional thinking, not final proof positive.

To test my Pentax K20D and 18-250mm Pentax lens (at 300mm equivalent) I shot a series similar to the Canon 5D Mark II and cropped the 14,500,000 pixel images to 900x300. To my delight I discovered that the body-integral Image Stabilization in my Pentax allowed me to shoot down to 1⁄25 sec at the 200mm setting. Because of this strong performance and—most importantly—because my Pentax delivers Shake Reduction (their term) with all of my Pentax lenses, I’ve declared the K20D the overall winner of the SBA competition. Other companies offer a selection of stabilized lenses—and for the most part, they’re terrific. But with my Pentax I can enjoy the Anti-Shake benefits with my macro lens, 50mm f/1.4, and other types of lenses that are not available in IS versions.

My biggest surprise came from the Canon EOS 40D plus Tamron 18-270mm VC (Vibration Control) combination. At 270mm (that’s equal to 432mm) I was steady down to 1⁄15 sec. At 1⁄12 sec I still got marginally acceptable results. (Please understand that this lens gave me superhuman powers I don’t normally possess; in fact, I’ve been known to poke myself in the eye when I comb my hair.) I really like this lens, especially its incredible 15x zoom range. It’s available in Nikon and Canon mounts only, and if it suddenly became unlawful to own more than one lens, this is the one I’d choose.

The SBA Test
Here’s how to calibrate yourself and your favorite camera and lens combination: First, select a suitable subject. I bought a $4 floral bouquet at the supermarket and commandeered a glass chime from one of my wife’s flowerpots. Work indoors or at least out of the wind—even the slightest breeze can move the subject and invalidate the results. Select an area where the lighting will remain as consistent as possible and dim enough that you will be able to shoot in Shutter Priority at low speeds without blowing out the exposure.

Start at a comfortable shutter speed—say, 1/125 sec or so—and slowly work your way down. For your first trial I suggest you make adjustments in full-stop increments. Once you’ve narrowed down your shake threshold you’ll want to fine-tune it in 1⁄2- or 1⁄3-stop steps. To keep yourself honest, click off the Image Stabilization and go through the same drill. That exercise will establish your SBA without IS.

Compact cameras with Anti-Shake features can be tested the same way. Remember to use good shooting habits (balanced stance, elbows in, stable posture, controlled breathing, press don’t poke, etc.) to steady the camera. Since most compacts are lighter than their D-SLR brethren they can sometimes be easier to accidentally shake.

Shake-Free Strategies
If you’re using a compact camera or a D-SLR/lens combination that doesn’t have Image Stabilization, there are other strategies for controlling camera shake. The best choice has three legs (see below). The next best alternative is to skirt the issue altogether by shooting at a higher shutter speed. It may be necessary to bump up the ISO setting (watch out for increased noise levels) or select a larger aperture. Shooting a 200mm f/2.8 telephoto, for example, is more satisfying than using a 200mm f/4 because you have one additional f/stop to work with. Use a one-stop faster lens and increase ISO by one stop and you have effectively improved your SBA potential by 200 percent. That’s equal to shooting at 1/500 sec instead of 1/125 sec and with a 200mm lens that brings a very noticeable improvement.

When pursuing the holy grail of image sharpness, be sure to make frequent use of the magnification feature on your camera’s Image Review function. Enlarge the image you just shot so you can monitor camera shake in real time. My antique Pentax *ist DS has a Custom Menu option that allows me to magnify just-shot images up to 12x with one button press—without repeatedly pressing the magnify button. It’s a great feature that I wish more cameras offered.

Three legs are better than two. A tripod is the only accessory that will improve every one of your images, and you can prove that to yourself once you’ve determined your SBA. Duplicate the test scenario mentioned earlier and turn the Image Stabilization function off. Dial up your SBA shutter speed and shoot one control shot. Then use a one-stop slower shutter speed and shoot the exact same subject again. Now, mount your camera on a sturdy tripod. Shoot at your SBA and shoot at a shutter speed one stop slower. When you critically examine the results you should find that your SBA shot is sharp and the other handheld shot shows blur. Both shots made using the tripod should be sharp—equal or better than the SBA image.

My SBA Test Results
Here are the results of my test on three camera and lens combinations, hardly definitive but certainly indicative of what you might find when you set out to discover your own personal SBA:

Camera Lens SBA (for Jon Sienkiewicz only)
Canon EOS 5D Mark II Canon 24-105mm IS 1/13 sec at 105mm
Canon EOS 40D Tamron 18-270mm VC 1/15 sec at 270mm (432mm equiv.)
Pentax K20D Pentax 18-250mm 1/25 sec at 200mm (300mm equiv.)
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