Optical image stabilization—also known as IS, OIS, or VR—is built into some lenses and cameras. It lets you take photos at slower shutter speeds than you ordinarily could. There are, however, some situations when you shouldn’t use it. Let’s dig in.
OIS works by having stabilized elements in either the lens or camera body that move to counteract small motions like the shake of your hands when you’re using a long lens. It’s rated in stops, so a 2-stop IS will let you use a shutter speed two stops slower than the reciprocal rule would suggest. For example, if you’re using a 200mm lens, the reciprocal rule says your minimum shutter speed should be at least 1/200th of a second; with 2-stop IS enabled you could use a shutter speed of 1/50th of a second. You can see that in the shot below. They were both shot at 1/40th of a second but IS was on for the photo on the right.
This is really the only situation where IS will materially improve your images. If your shutter speed is significantly faster than the reciprocal of the focal length, then it just won’t matter whether you use IS or not. The golden rule of IS, then, is to make sure it’s on when you’re using a long-ish lens in low light—or any lens in really low light. That’s when you absolutely should use it, and it will help. Outside of that, it either doesn’t help or, as we’ll look at, might make things worse. So, let’s look at when you shouldn’t use IS.
You’re Using a Tripod
When you’re using a tripod, your camera is locked down and stable already. IS only works when there is a movement to counteract. If there’s no movement, then the gyroscopes and other stabilizing elements can introduce a small amount and lead to less sharp shots.
RELATED: How to Select and Use a Tripod
Or at least, that’s the theory. It’s certainly true of older IS systems, but most newer (or high end) setups can detect when the camera is mounted on a tripod. The reality is, however, that IS will not help if you’re using a well-secured tripod, so it makes sense to turn it off even if you are using a camera or lens with an IS system that will detect the tripod.
You’re Panning
If you’re panning to track a moving subject—like in sports or wildlife photography—then you need to be careful about using IS. Lenses designed for these sort of subjects normally have a dedicated IS mode that turns off one axis of the IS so that it won’t interfere with your photos.
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from How-To Geek https://ift.tt/2BxooTN
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