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Tuesday, May 24, 2011

The Promise Of Stabilization

Between image-stabilized lenses, in-camera stabilization and high-ISO technology, the game has changed for photographers seeking the freedom to shoot handheld

This Article Features Photo Zoom
More recently, DSLRs such as the pro Canon EOS-1Ds Mark IV and the pro Nikon D3S gave us a preview of what to expect in the next few years as sensor technology and image-processing engines continue to push the high-ISO limit. Both DSLRs can be set to an ISO of 102,400, allowing proper exposures in near-dark conditions far below the sensitivity limits of the highest ISO 35mm films (those topped out at ISO 3200, with push-processing to ISO 12,800). While 100,000-plus ISO settings produce images that are fairly noisy and have low color saturation even in these pro models, many shooters are discovering that photos shot at ISO 6400 (six stops above ISO 100) and 12,800 (seven stops) can produce remarkably good images—in some cases, rivaling the noise levels and color shot on their previous models at ISO 800 and 1600!

It All Adds Up: High Advantages In Low Light
When you combine the benefits gained from image-stabilized lenses or cameras, wider-aperture lenses and extremely high ISOs, you're looking at a potential seven- to 10-stop increase in light sensitivity when shooting handheld shots with the latest APS-C DSLRs, and a 13- to 14-stop advantage when shooting with the pro Canon and Nikon models mentioned earlier. That's compared to a digital or film camera set to ISO 100 using an ƒ/4 or ƒ/5.6 zoom lens without IS.

The real advantage goes beyond the numbers, as increased low-light capabilities allow DSLR shooters to capture still photos, and possibly HD videos, in ambient low-light situations that once were impossible to master without a tripod or additional lighting. Perhaps ghost images no longer will be limited to lens refractions.

In-Lens IS Vs. In-Camera IS

An in-lens stabilization unit. These technological wonders feature microprocessors and moving optics.
Both in-lens element-shift stabilization and in-camera sensor-shift stabilization work on the same basic principle: Gyroscopic angular-velocity sensors in the lens or camera body detect camera movement and transmit that data to an onboard microprocessor. The processor interprets the motion data, incorporating information about the lens focal length, and calculates the needed degree of compensation, then signals the stabilization system to move the stabilizing lens group or the sensor itself the proper amount and direction to compensate.

Each manufacturer's system varies in its details, but the result in all cases is that you get sharper handheld images.
Early systems claimed a two-stop gain (i.e., if you normally could get sharp handheld shots with the lens at a shutter speed of 1⁄60 sec., the stabilization would give you similar results at 1/15 sec.). Today, some systems claim four to five stops of gain (you could handhold the aforementioned lens down to ¼ or ½ sec.)—this may be stretching it a bit, but even the original stabilizers were quite effective, and if you shoot handheld, you'll love stabilization, be it in-lens or in-camera.

Canon introduced in-lens stabilization with the EF 75-300mm ƒ/4-5.6 IS USM telezoom in 1995.
Today, Canon (IS), Nikon (VR), Sigma (OS) and Tamron (VC) offer lines of lenses with in-lens stabilization. Konica Minolta introduced sensor-shift stabilization in the Maxxum 7D in 2005. While Konica Minolta no longer makes DSLRs, today Sony (which obtained Konica Minolta's DSLR assets in 2006), Olympus and Pentax offer DSLRs with sensor-shift stabilization.

While early stabilizers had just one mode, some of today's stabilized lenses offer more than one. For example, a Canon IS lens might offer Mode 1, which resists both vertical and horizontal camera shake, and Mode 2, which resists only shake in only one direction, allowing you to pan or track an action subject. A Nikon lens might offer Normal VR (for normal shooting) and Active VR (for shooting when you're moving, as when shooting from a moving vehicle). Check the instruction manual for your stabilized lens or camera body for specific operating directions.

Some systems compensate for vertical and horizontal (up/down and left/right) motion, some for pitch (rotating up or down) and yaw (rotating horizontally). Some, like Canon's EF 100mm ƒ/2.8L Macro IS USM lens, can compensate for both, thanks to the acceleration sensor, as well as angular-velocity sensors.

Michael J. McNamara is a professional photographer, founder of The McNamara Report and a longtime photography industry insider. You can see more of his work at www.mcnamarareport.com.


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