Optical image stabilization (OIS) is the term given to a set of camera lenses and other apparatus to help ensure any camera shake or wobbly camera handling doesn’t cause the captured images or videos to turn out blurry or shaky. OIS replaces the tripod to a certain extent. OIS achieves stability by mobilizing the lens elements or moving the lens to compensate for the camera shake. Besides stabilizing the camera optically or through hardware, one can also resort to digital or software-induced stabilization, referred to as electronic image stabilization (EIS), which is a slightly less professional way to stabilize shots.
Though OIS gained mass attention after blending into smartphones, not many know the technology has been in existence ever since the 1990s. During those days, the technology was used in compact point-and-shoot cameras and in single-lens reflex (SLR) cameras.
An OIS module comprises motors, floating lens, and gyroscopes. The stabilization process kicks in before the image is being captured or prior to the light from the image getting registered on the charge-coupled device (CCD), the image sensor or a light-sensitive circuit that accumulates and presents all data about the image. This is possible thanks to a prism-like arrangement positioned before the lens, which is created by a couple of glass plates that have bellows between them. Bellows is usually an expandable portion of a camera that helps with lens movement. In OIS, the bellows setup is made with liquid. This liquid helps create the prism effect.
OIS uses a couple of gyroscopes to detect the angle and speed with which the camera is moving, and then communicate movement measurements to the image sensor via a stabilization chip, so that the sensor can compensate for the shake. The lens then computes how the glass plates should move so that the shaky camera handling doesn’t disrupt or cut the sensor’s optical path, or the path between the subject and image sensor. One of the glass plates moves the image up and down, and the other plate moves vertically, with the help of electromagnet motors. When there’s no camera movement, the glass plates remain static.
OIS and Smartphones
OIS is much more useful in smartphone cameras than traditional cameras because the smartphone camera lens is smaller and it can only take in a certain amount of light. The smaller lens means higher exposure time and increased probabilities of camera shake and blurry pictures.
So how does OIS help smartphone photography? Photographers with an OIS-enabled smartphone camera can capture better images in low-light conditions, when capturing macro shots, or any other scenario when there’s noticeable haphazard camera movement. Since smartphone cameras have smaller sensors than regular cameras, the phone cannot capture as much detail in its shots or provide a dynamic range on par with dedicated shooters. This means low-light performance or taking photos in artificial light would always be inferior on smartphone cameras.
When taking pictures on a smartphone in low light, the shutter speed slows down so that more light can enter the camera. With a slower shutter speed, the camera would take slightly longer to focus and capture the image. This delay only makes the shot more susceptible to camera shaking and unsteady handling. OIS helps reduce this shake, and this is why OIS-equipped smartphones take better and much brighter pictures in low light compared to smartphone cameras without OIS.
OIS happens at the lens-level, which means the photographer can see the stabilization live through the camera viewfinder. This is generally how photography professionals want their stabilization to kick in because it gives them more control over the process, which helps compose the shots better.
OIS is most efficient when capturing long shots since the lens’ stabilization system has a much bigger canvas to compensate for the camera shake, which gets magnified when zooming in on the subject or using a telephoto lens.
OIS cannot handle subject-induced blur – particularly when the subject is moving extremely quickly. All it does is counter camera shake, which again it can address only to a certain level. Moreover, OIS takes time to get its act together since its mechanisms are based on physical components. EIS, on the other hand, is much faster because it does the processing electronically.
OIS is a fairly substantial hardware component and is also not cheap, which means phone manufacturers can justify using OIS only in their high-end phones. But that’s still not a given as some high-end smartphones, such as the iPhone 6S and the Nexus 6P, had omitted the feature when OIS in smartphones was a norm.
Using OIS with a Tripod
If the camera is being positioned on a table or tripod, image stabilization is redundant – in fact, it’s counterproductive in most cases. The stabilizer stays active even when there’s no camera shake. This could result in the lens constantly engaging in a never-ending loop, which could damage the equipment. It’s therefore wise to turn the stabilization feature off when using the camera on a tripod or when camera shake is not expected.