A term we come across a lot when it comes to DSLR and a lot of high-end smartphones. So what exactly is this and what is the idea behind OIS?
In order to understand OIS, it is important that we understand the human eye because the camera lens can be compared to a highly downgraded version of the human eye. Let us consider this example while running or jogging how is it that you have a clear vision without any blur? This is because the human eye has an in-built mechanism that moves the pupil in the direction opposite to the direction of movement in order to nullify the shake that would result from the movement. That is when you jump, your pupil moves downwards to counteract the shaky vision that might result due to the sudden upwards movement.
When there is no optical image Stabilization, then a video recorded on the move would be jerky and an image captured by the camera under less than ideal lighting conditions would be blurry. A camera with OIS provides a stable video while moving or a clear image when the natural lighting is less than optimal and the shutter needs to be open for a longer time to let in more light into the sensor.
Let us consider the first case where an image needs to be shot in less than ideal lighting conditions. Now it is important to understand that the slower the shutter speed the more the light let into the sensor. This means that when the natural lighting is less the shutter would remain open for a longer duration to let in more light into the sensor to form an image. But when the shutter is open for a longer duration then the light may not fall on the individual pixels in the sensor accurately due to shaky hands and this results in a blurry image. In order to ensure that the blur in the image is reduced the camera lens judges the motion of the hands with the help of a gyroscope and physically moves in a direction opposite to the direction of movement (of your hands) and thereby ensures that the sensor remains stationary for the pixels in the sensor to illuminate properly.
In the case of a video, the lens moves in the direction opposite to the direction of movement thereby ensuring that enough light is let into the sensor to form a moving picture.
Does OIS help in producing a better image? More often than not it helps in providing a sharper image especially in situations where the natural lighting is far from ideal. Nowadays we have electronic image stabilization (EIS) replacing OIS in smartphones and this too helps in reducing the jitter while recording video or shooting an image but the downside of this is that the image formed is slightly cropped along the edges which results in the final image not being the same as the one you saw on the viewfinder before clicking the shutter.
OIS or EIS? Which is better? While both the technologies strive to achieve the same end result, OIS does this with specialized hardware while EIS does it through software. Companies prefer to incorporate EIS on mid-range phones as they don’t need to spend a lot on designing a module for physical movement of the camera lens to aid OIS but in the long run, OIS has the edge as it is a functionally aided by hardware while EIS is aided by software and can tend to become buggy with time if not supported properly.