Tutorial: Optical vs Sensor-shift Image Stabilization
When we hand hold a camera and press the shutter release button to take a picture, we ever so slightly move the camera. This “camera shake” often results in a blurred picture. Image stabiliation (I.S.) is a technology that either moves a lens element (Optical I.S.) or the camera’s image sensor (Sensor-shift I.S.) to compensate for camera shake and reduce or eliminate the blurring.
But is one better than the other? You would think so by reading the discussions on some forum boards. There is a difference in how they work but there is no better I.S. Each has its own strength and weakness.
Optical Image Stabilization
As its name implies, Optical I.S. is an image stabilizer technology that is based on the optics of the lens: optical image stabilization shifts a lens element inside the lens to compensate for camera shake.
- Pro: Because it is lens-based, it is able to stabilize the image the lens projects on the image sensor, and hence the image you see on the screen. This makes it easier to compose and frame your scene, especially when using a long telephoto lens.
- Pro: Optical I.S. can be optimized for each lens.
- Con: Optical I.S. is lens-based so if you want image stabilization in a particular lens, you need to purchase the I.S. version of that lens. A lens with I.S. can be much more expensive than its counterpart without I.S.
Sensor-shift Image Stabilization
As its name implies, Sensor-shift I.S. is an image stabilizer technology that is based on the camera’s image sensor: sensor-shift image stabilization shifts the image sensor inside the camera to compensate for camera shake.
- Pro: Sensor-shift I.S. is inside the camera so any lens you attach to the camera automatically takes advantage of the built-in stabilization, potentially saving you mega bucks from having to buy the I.S. version of a lens.
- Con: Because it is sensor-based, it is not able to stabilize the image the lens projects on the image sensor, and hence the image you see on the screen. The stabilization takes effect only when you press the shutter release button to take the picture. So, when you look into the screen, there may be times when you will find it difficult to compose and frame your scene properly. This is especially true when using a long telephoto lens: any slight movement on your part is magnified and the subject moves erratically on screen.
You will find that most DSLRs use Optical I.S. though there are a couple that use Sensor-shift I.S. I have no preference either way, though I understand how the attraction of being able to attach any lens to a camera and automatically gain image stabilization (i.e. Sensor-shift I.S.) can be attractive. If you are on a budget and plan to buy a number of lenses for your DSLR, then Sensor-shift I.S. may be the way to go. Most professionals do not care one way or another and buy whatever equipment they need to get the job done.
On compact digicams where you cannot change the lens, optical I.S. definitely has the advantage since it can stabilize the image on screen. For this reason, I believe Optical I.S. is preferable on super zoom digital cameras. On other digicams, it really makes no difference whether the I.S. is optical or sensor based.
When I.S. Matters Not
- If you always use a tripod to take pictures, e.g. for landscape photography, then I.S. is not important to you. In fact you need to turn I.S. off when your camera is on a tripod or the mechanism itself might cause unintended blurring!
- Consider also that no amount of I.S. (optical or sensor-shift) might be enough to stabilize a super zoom camera or a long telephoto lens when the lens is zoomed maximum, so hand holding your camera may be out of the question. Once you use a tripod, you need to turn I.S. (optical or sensor-shift) off.
- If you always take pictures in bright conditions, whether in the sunny outdoors, using flash or in a well-lit studio, the shutter speed the camera uses is fast enough so that camera shake is not a factor.
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