The cameras in our smartphones keep getting better as they gain tech and features previously reserved for high-end cameras. One such example is Optical Image Stabilization (OIS) which promises less blurry images and smoother video. Here we look at exactly what OIS is, how it works, and whether it's a feature you'll want in your next smartphone.

Optical Image Stabilization has been around commercially since the mid-90s when it started being used in compact cameras and SLR lenses as a method of letting photographers shoot longer exposures without reaching for a tripod. It works by moving lens elements to counteract wobbly hand-induced camera shake, thereby reducing blur.

Twenty years later, OIS has now become a mainstay feature of flagship smartphones where it's arguably even more useful. Because the image sensors used in smartphones are so much smaller than those in traditional cameras, they can struggle to get enough light in some conditions. As such they'll often end up using exposure times which increase the likelihood of camera shake and blurry images.

OIS works by controlling the path of the image through the lens and onto the image sensor. This is done by understanding the camera's movement using sensors such as gyroscopes, and calculating how the lens needs to move to counteract this. The lens module is then generally moved sideways or up and down, normally by using electromagnet motors. All of this happens as the image is recorded to reduce camera movement blur.

Other stabilization methods include the usually inferior digital stabilization, which uses software to reduce the impact of less than steady hands, and sensor-shift stabilization. The latter is currently seen on many mirrorless cameras and some DSLRs, and instead of moving the lens, moves the sensor to counter camera movement. This is a technology we'd expect to see appearing on smartphones over the next couple of years.

What this means for smartphone photographers toting OIS devices, is that they're able to use their camera in situations where they wouldn't normally have been able to handhold a blur-free shot. This could be a lower light setting, shooting a close-up, or generally anytime you'd otherwise notice camera shake. Examples might include night-time cityscapes, close-up shots of that coffee you want to Instagram, or posed shots of friends at a party that doesn't have the best lighting.

However, stabilization isn't a fix for all types of blur. OIS can't do anything if blur is caused by your subject moving too fast for your exposure to freeze the action; it only works to counter camera shake. Therefore it's important to question whether the blurry images you want to fix are caused by camera movement, or other factors which would be best addressed by changing camera settings.

In terms of video recording, the addition of OIS can again offer a huge benefit. Here the constant adjustment of the lens to counteract camera movement can result in considerably less wobbly footage. Sure, it's not going to offer the same level of stability as an external gimbal, or smooth out large camera movements, but it could make your video footage a lot more watchable. It's also better than trying to fix wobbly footage in post production with software, which can be very hit and miss.

Because of the cost implication and size increase OIS gives a camera module, it's more commonly found in larger and higher-end smartphones. Recent examples include the Samsung Galaxy S7 and S7 Edge and the LG G5. Notably, while the larger iPhone 6 Plus and 6s Plus do feature OIS, the standard-sized iPhones do not. Presumably this is because of the size limitation inside their smaller bodies.

It's also worth considering that not all OIS is created equal. Traditional camera manufacturers tend to describe the ability of their stabilization systems in terms of it being equivalent to a however-many step faster shutter speed, allowing them to be compared. But smartphone makers seem reluctant to do the same simply stating whether a device has OIS or not.

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