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Another low-light photography advantage
Anti-shake technology has improved since it was introduced over ten years ago and has helped to reduce shaky photos. What, exactly, is it?
The problem: When shooting in low light, you need to shoot either at wider apertures, higher ISOs, or slower shutter speeds. If it’s really dark, you may need all three but even then, it’s possible that you may shake the camera during exposure. You could use a tripod but this is not always an option. So, handheld photos in low light have been plagued by motion blur. Sometimes motion blur is blatant, other times it is subtle and the picture simply appears soft overall.
The solution: Anti-shake technology, which has been around since 1995, when Canon introduced the 75-300mm f/4-5.6 Canon IS lens, followed by Nikon’s 80-400mm f/4.5-5.6 D VR model. Scores of lenses with anti-shake followed, as did many compact cameras and some DSLRs with anti-shake technology built in. Why? Because anti-shake can give anywhere from one to three or four stops of additional steadiness.
What does “one to three or four stops of additional steadiness” mean? Without anti-shake, she slowest shutter speed you should use should be around the same as, or slightly higher than, your lens’s focal length. So, if you’re shooting with a 50mm lens, you should not shoot below 1/60 sec. But if you use anti-shake that is supposed to give you two additional stops of steadiness, you can set your shutter speed as low as 1/15 sec—two stops slower—and shoot without shake. If it can give you three stops, that would be 1/8 sec, and so on.
Casio's EX-ZR10 does a pretty good job reducing shake at 35mm (35mm equivalent) at 1/10 second.
Moments later, I turned anti-shake mode off. Other camera settings remained the same. Result? A fuzzy dog!
Certain variables can affect the effectiveness of anti-shake. For instance, if you just had a couple of cups of coffee, your hands may be a bit shakier and you may not get the full benefit of anti-shake (when I was at Popular Photography a number of years ago, we actually conducted one of our wackiest tests, loading up a willing editor on Starbuck’s coffee and having him take pictures of a target in, constant, subdued light at the same shutter speed over the course of an hour. The caffeine did, indeed, affect his ability to hold the camera steady but he was wide awake!)
Fortunately, just about every compact camera currently on the market and many lenses for interchangeable-lens cameras offer anti-shake, which has steadies the shot so you can get a shake-free photo even at low light and slow shutter speeds.
Different names for the same thing
There is no standardized name for anti-shake technology and each camera maker has its own name for it. They are, by company:
- Canon : IS (Image Stabilization)
- Casio: Anti-Shake
- Nikon: VR (Vibration Reduction)
- Sony: Optical SteadyShot (for compact cameras), SuperSteadyShot (SSS for DSLRs)
- Panasonic & Leica: MegaOIS
- Tamron: VC (Vibration Compensation)
- Pentax: SR (Shake Reduction)
- Sigma: OS (Optical Stabilization)
I shot this flower in deep shade with a 55mm macro lens in the shade, and since macro magnifies shake, I had anti-shake turned on. See how it looked without anti-shake, above, and with anti-shake, below. The extra couple of stops of anti-shake also allowed me to stop down the aperture one more stop for more depth of field.
OK, not quite the same thing, but the same goal
There are three different technical approaches to IS. There’s lens-based IS, sensor-shift IS, and digital IS. Let’s look at each.
Lens-based anti-shake uses a floating lens element that is moved via electromagnets to compensate for vibration, which is detected using a pair of gyroscopic sensors. One sensor detects horizontal movement and the other detects vertical movement. This is most effective when moving the camera up and down or side to side, but not for panning. Some more advanced lenses have a separate mode for “active” subjects.
The advantage of lens-based anti-shake is that you can see the effect of the stabilization in the viewfinder when shooting with a DSLR. The disadvantage is that you need to buy lenses with anti-shake built-in, and these usually cost more than equivalent lenses that don’t offer anti-shake.
Nikon and Canon use lens-based IS for their interchangeable lenses.
Sensor-Shift anti-shake is built into the camera rather than the lens. The sensor is moved to correct angular errors via a gyroscope which communicates with an actuator that moves the sensor. The degree of motion compensation is adjusted based on the focal length of the lens—information that is automatically communicated to the camera from the lens via the electronic sensors found on the mount.
The advantage of Sensor-Shift is that if you are using an interchangeable lens camera, any lens that fits that camera will benefit from the technology. The disadvantage is that if you’re using an SLR, the image you see in the viewfinder will not appear to be stabilized even when stabilization is turned on.
Pentax, Olympus, and Sony DSLRs use Sensor-Shift, as do most compact cameras.
Digital Image Stabilization. For video, the technique shifts the electronic image to counteract the motion, using pixels outside the visible frame. For stills, Digital Image Stabilization usually simply means the ISO is boosted so the camera can choose a faster shutter speed. The disadvantage of this method is that while camera shake might be avoided, the picture will likely be ruined by massive amounts of digital noise or grain so there's really minimal advantage to this method.
A caveat for tripod users
Ironically, anti-shake technology and tripods don’t go together. If you leave your camera’s or lens’s anti-shake mode on with the camera mounted on a tripod, you can end up getting shaky results. Why? Because the lens group (if the the anti-shake is in the lens) or sensor (if it's camera-based) is unlocked when in anti-shake mode and can be moved by the electromagnetic coil surrounding the elements or sensor, causing blur. Turning anti-shake off will lock the lens group or sensor in place. So be sure to turn anti-shake off when using a tripod, and let the tripod alone keep the camera steady!
Bottom line: Anti-shake tech works!
The bottom line with optical and sensor-shift anti-shake is that it can be effective, and is one of several valuable tools that are widely available to photographers who want to take great pictures in low light.