Optical and electronic stabilisation: what each one fixes and how to tell them apart

Stabilisation is the phone camera feature with the widest gap between what it is called and what it does. Two mechanisms share the name, they solve different problems, and a specification sheet will sometimes list the cheaper one in a way designed to be read as the expensive one.

Optical stabilisation

A small actuator moves the lens element — or, on some designs, the sensor — to counteract the movement the gyroscope reports. The correction happens before the light is recorded, so nothing is lost: the full frame is used, and the exposure can be longer without smearing.

That last point is the real benefit. In dim light a camera needs time, and hand shake is what prevents it from taking any. Optical stabilisation buys a meaningful amount of exposure time, which is why phones with it produce visibly cleaner night photographs than phones without it, independent of sensor size. It is also why it matters far more on the main camera than anywhere else.

Its limits

It corrects small, fast movements — the tremor of a hand. It does nothing for walking, for the lurch of a vehicle, or for a deliberate pan. The range of physical movement available to the actuator is small by definition.

Electronic stabilisation

The camera records a frame larger than the one it delivers, and the software slides the output window around inside it to cancel movement, correcting for the rolling shutter distortion that makes handheld video wobble. Nothing moves mechanically.

The costs are a permanent crop — a visibly narrower field of view when stabilisation is on — and a processing load, since the correction happens per frame. The benefit is that it handles the large, slow movements optical stabilisation cannot: walking, running, riding. For video, good electronic stabilisation matters more than optical.

It also does nothing whatever for a still photograph in low light. The exposure is what it is; shifting the output window afterwards cannot unblur a smeared frame. A phone advertised as stabilised that turns out to be electronically stabilised only will be exactly as shaky as an unstabilised one in a dim room.

Telling them apart

• Read the specification for the word optical, and read it per camera. "Stabilisation" without qualification usually means electronic. A phone frequently has optical stabilisation on the main camera and none on the ultra-wide, and the sheet may list the feature once as though it applied to all of them.
• Listen. In a quiet room, with the camera open, tilt the phone gently and hold it near your ear. An optical module makes a faint mechanical sound as the element moves and settles. An electronically stabilised camera is silent.
• Watch the preview. Switching video stabilisation on and off changes the field of view if it is electronic. If the framing does not change at all, the correction is optical.
• Try it in the dark. A handheld photograph in dim light, taken twice at the same distance, tells you more than any of the above: optical stabilisation shows up as a usable frame where the other phone produces a smear.

Where the two are combined

Most good phone video uses both at once: the optical module removes the tremor, the electronic layer removes the gait, and the result is steadier than either alone. Some makers give this combination a name of their own, which is worth decoding rather than accepting — the question is always whether there is an optical module underneath.

Sensor-shift designs, where the sensor rather than the lens moves, can correct a slightly wider range of movement and can also assist multi-frame capture. They are a premium feature and are normally stated explicitly.

What to do with this when buying

If you photograph indoors and after dark, optical stabilisation on the main camera is close to a requirement, and its absence is not compensated for by a large headline resolution — see the piece on binning. If you shoot video while moving, check what the electronic stabilisation does to the field of view and whether it is available at the resolution and frame rate you intend to use, because it is frequently disabled at the highest settings. And check the ultra-wide separately: it is the camera most often left unstabilised, and the one most often used for the wide establishing shot that then wobbles.