The Promise Of Stabilization

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Image-stabilized lenses and cameras let you capture sharp, handheld photos at lower shutter speeds than ever before, while supersensitive sensors let some DSLRs shoot in the dark. So is it time to retire your tripod?

Sony SLT-A55, Olympus E-5 and Pentax K-5 cameras provide sensor-shift stabilization.

Most experienced photographers agree that a sturdy tripod is the best tool to use when shooting in low-light situations without a flash. Because tripods reduce camera shake and other vibrations, they enable you to use slow shutter speeds to balance exposures or extend the depth of field in your photos by using small apertures—all while keeping your ISO setting low to maximize image quality. But now that image-stabilized lenses and camera bodies are readily available, and supersensitive, low-noise sensors are appearing in the latest DSLRs, are tripods losing their mass appeal?

That's a trick question, since another key tripod benefit is to support the mass of equipment pros and advanced shooters truck with them, including heavy cameras, long lenses, WiFi adapters and battery packs. With the arrival of HDSLRs, the load increases with accessory microphones, rack-focusing devices and video lights. Add the benefits that fluid heads provide for video panning and tracking, and tripods actually may increase in popularity.

Which Is Better: Lens IS Or Camera IS?
If you're a dedicated DSLR still shooter who likes to travel light, a tripod may soon be the last option you choose for improving your low-light photos and depth of field. Your most affordable and lightweight option is either an image-stabilized lens or a camera body with built-in sensor-shift IS.

How well do these two systems reduce vibrations, and is one better than the other? The answers depend on a number of factors, including the camera brand you own, your physical traits and the subject you're photographing. Currently, manufacturers such as Canon, Nikon, Panasonic and Sigma only offer lens-based image stabilization (called IS, VR, Mega O.I.S. and OS, respectively) for their DSLRs. On the other hand, Olympus, Pentax and Sony only offer DSLR models with sensor-shift IS. Note: Even if you purchase third-party IS lenses from Sigma, Tamron or Tokina to use with a sensor-shift body, only one IS system will work at a time.

Claims for both types of image stabilization range from two to four stops of improvement over the maximum recommended shutter speed for cameras and lenses without IS (see "The Reciprocal Shutter Speed Rule" sidebar). That means that if the slowest recommended shutter speed is 1⁄200 sec., without IS, you may be able to capture sharp handheld shots all the way down to 1/12 sec. with a lens or camera, providing a four-stop advantage. In my experience, however, and based on several lab and field tests I've done, improvements from the best IS lenses and IS cameras are rarely higher than three stops—and that advantage is only reachable when using telephoto lenses with focal lengths over 100mm. With normal and wide-angle lenses, IS improvements are less noticeable and not as obvious on either system. The benefits of IS also decrease at higher shutter speeds, so if you dial in 1/400 sec. with a 200mm lens to reduce vibration from a moving vehicle (or from the four cups of coffee you drank), or chose 1/600 sec. to freeze action in the scene, the IS won't significantly improve the shots.

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The Canon EF 70-200mm ƒ/2.8L IS USM, Sigma 70-300mm ƒ/4-5.6 DG OS and Tamron 18-270mm ƒ/3.5-6.3 Di II VC lenses feature in-lens stabilization.

Other significant differences between both IS technologies affect the way you shoot and the price you pay for lenses. Cameras with sensor-shift IS generally work well with any compatible lens, including older ones. IS lenses tend to cost a bit more than their non-IS counterparts, so you have to factor that into the equation. However, only image-stabilized lenses can be set to show the stabilization effect through the camera's optical viewfinder. A few sensor-shift bodies let you preview the IS effect in Live View mode via the large LCD or through an electronic viewfinder (when it's available). Some shooters find using a live IS preview in either system to be advantageous, while others note how fast it drains the camera battery.

The best IS lenses also feature special panning modes or switches for use when you're tracking a moving target. These produce superior results by ignoring side-to-side motion and only reducing shake along the vertical axis. Other lenses can detect when the camera is set on a tripod automatically and turn off the IS so you can save battery life. Finally, when it comes to shooting video, both IS systems can help reduce shake to some extent, but IS lenses are generally quieter and further away from the built-in camera microphone. At least one zoom lens from Panasonic has a completely silent IS engine.

High ISO Changes The Rules For Working Without A Tripod
You may have noticed that neither the light-gathering capacity of the lens (determined by its maximum aperture) or the ISO setting of the camera is factored into the Reciprocal Shutter Speed Rule. These two features are only indirectly related to the amount of blur you can expect when shooting at low shutter speeds and, instead, determine whether you need to use a low shutter speed at all to produce a proper exposure. A brighter lens and higher ISO settings both let you use a faster shutter speed in a given low-light situation. Unfortunately, large-aperture telephoto lenses are expensive and rarely give you more than a two-stop advantage over a cheaper lens. But that two-stop advantage (for example, ƒ/2.8 vs. ƒ/5.6) is worth the price if you're an avid low-light shooter or if you want the added depth-of-field separation provided by wider apertures.

Increasing the camera's ISO to improve low-light performance can give you several more stops of improvement compared to a brighter lens or image stabilization. Many point-and-shoots do this automatically when their "electronic" image-stabilization feature is turned on. However, the price you pay for increasing ISO is a decrease in image quality. How much it decreases depends on the camera and its sensor. Most DSLRs let you dial up ISO to gain a three- to five-stop improvement in light sensitivity (compared to the camera's base ISO) before image quality becomes unacceptable. For example, assuming you own a fairly modern APS-C DSLR with a base ISO of 100, you may find images shot at ISOs from 800 (three stops) to 3200 (five stops) to be acceptable.

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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.