OIS uses a movable lens or sensor to physically counter camera shake, sharpening photos and videos. Essential for low-light photography and zoomed video.
OIS mechanism: gyroscope detects hand shake, then a voice-coil motor shifts either the lens glass elements or the entire sensor to compensate. This allows 2–4 stops slower shutter speed (e.g., hand-hold 1/15 second instead of 1/120).
OIS types: Lens-shift OIS: one or more lens groups move. Lighter, doesn't affect light path uniformly, most common. Sensor-shift OIS: entire sensor moves on a platform. Affects all focal lengths equally, found in premium phones (iPhone 15 Pro Max, Pixel 9 Pro XL). More effective but pricier.
OIS benefits: - Low light: enables hand-held shots at 1/15 or 1/30 without blur where unOIS would need 1/60 or 1/120. - Video: eliminates jitter walking/panning, professional-looking stabilization without gimbal. - Zoom: stabilizes telephoto, which amplifies shake (2× zoom = 2× shake).
OIS power draw: minimal (continuous gyro polling + occasional motor pulses), <5 mA during use.
Limitations: OIS can't stop extreme motion blur (fast panning), and it can't improve depth blur from a small aperture.
Electronic Stabilization (EIS) is software-based: crops image and shifts frames to align motion. Less effective than OIS but all phones have it; OIS + EIS combined ("hybrid stabilization") is the best result.
When to prioritize OIS: primary camera telephoto zoom, low-light videography, astrophotography. Not essential for daytime still photos (fast shutter speeds available).