Left: Crop from a handheld Night Sight shot of the sky (full resolution image here). There was slight handshake, so Night Sight chose 333ms x 15 frames = 5.0 seconds of capture. Right: Tripod shot (full resolution image here). No handshake was detected, so Night Sight used 1.0 second x 6 frames = 6.0 seconds. The sky is cleaner (less noise), and you can see more stars. (Florian Kainz)

Stacking many images has the advantage of averaging out noise while increasing signal, but adds the problem of aligning images taken some time apart. The camera's software (which ought to be largely independent of the phone hardware) aims to handle this intelligently.