How OIS (Optical Image Stabilisation) works

Be it the Nothing phone (1) or any of the other upper-midrange or flagship phones you’ve been eyeing, one term you’ve probably come across multiple times is OIS, or optical image stabilisation. This camera feature can today be found on many smartphones across categories. OIS is known to make your photography experience better, and brands advertising the same will not skip telling you that. But how exactly does the tech work? In today’s edition of tech InDepth, we’ll be taking a closer look at OIS and how it works.
What is OIS?
Optical Image Stabilisation is a technology used in smartphones and cameras that helps stabilise the photo-taking components of your phone or camera to minimise or completely negate the ‘shake’ in images. This lets you take crisper shots from your device even when it’s held in your hand.

OIS is particularly helpful when you want to take photos in the night or low-light scenarios as it keeps your camera stable for longer so it can take in more light when in a darker setting, delivering brighter and more pleasing photos that otherwise would likely need a tripod or some other form of stabilisation to achieve.
Note that OIS only helps with a shaky camera, not a shaky or fast-moving subject. So, if you’re thinking OIS would help you get better shots of your pet running around, it won’t.
OIS vs EIS 
OIS should not be confused with EIS (Electronic Image Stabilisation) which may sound like a digital implementation of the same tech, but is actually a different technology entirely. EIS is used for recording video and works shaking around the various frames in a video to compile what appears to be a more stable footage with reduced shakiness.
In fact, it is possible for the same camera to have both OIS and EIS support, OIS for photos and EIS for videos, as we see on the primary camera of the Nothing phone (1), for instance.
Types of OIS
OIS mechanisms are achieved using a combination of electromagnets, gyroscopic sensors and rotors to allow either the lens or the sensor itself to change its angle when an image is being taken.  The lens-moving mechanism is used on bigger cameras, and since they involve movement of the lens, this mechanism requires some dance between the lens and the sensor itself. The result is a sharper image as the image stays constant on the sensor while the lens moves. However, due to the space required, such a mechanism is not usually seen on smaller devices, like phones.

The other kind of OIS implementation involves the movement of the sensor. This requires relatively much lesser space, allowing such a setup to ex in smartphone camera setups. However, this results in lower quality images compared to the moving lens mechanism.
How it works
As we mentioned above, optical image stabilisation works using a complex yet compact mechanism of sensors, electro magnets and rotors. These components help shake the sensor around, which is usually tethered to the rest of the phone using small spring-like structures, allowing it movement up to a certain degree.
When your hand shakes during taking a picture, the phone and hence, the camera setup, shake with it. The sensors in an OIS mechanism quickly sense the direction of movement when this happens and send signals to the electromagnets which can now move the sensor around as desired.

When your shaking camera moves in one direction, be it horizontally or vertically, the electromagnets push the sensor the opposite way to compensate. This allows the sensor and the image to stay relatively motion-free to an extent, with respect to each other.
Check out this video of an eagle stabilising its head to keep its sights on a prey. Head stabilisation is key for birds like eagles and owls to hunt prey as shakiness could mean momentary loss of vision, and the prey escaping.

An OIS camera sensor will shake around in a similar manner inside the body of the phone to compensate for horizontal and vertical shake. As you may have guessed, this works only for small movements, so an OIS camera will not save your pictures if your hand is moving around and not simply shaking. While the tech helps stabilise your photos, giving you cleaner shots, you will still need motionless arms to make the most out of your OIS-enabled smartphone camera.