Optical Image Stabilisation
Stabilisation achieved by moving a lens group to counteract camera shake.
Measured in
stops
In depth
Gyroscopic sensors detect angular movement and shift a floating element to keep the image steady on the sensor. Because it works inside the lens, it can be tuned to that focal length, which makes it especially effective on long telephotos where sensor-shift systems struggle. Most implementations offer a panning mode that stabilises only one axis.
Examples in practice
A stabilised 400 mm lens allows sharp handheld frames at 1/60 s, four stops below the reciprocal rule.