iPhone 6 Plus is Apple's first smartphone to feature Optical Image Stabilization
According to Apple, OIS works with the new iPhone’s gyroscope, the A8 chipset, and the M8 motion coprocessor to literally move the camera lens in order to compensate for a user’s eventual hand shake when taking photos. Thus, photos should be crisp and blur-free, even in low light conditions.
Optical image stabilization aside, the rear cameras on the iPhone 6 and iPhone 6 Plus are identical: they’re the same 8 MP iSight units with f/2.2 aperture, True Tone dual-LED flash, and 1080p video recording (up to 60fps) with cinematic stabilization. While Apple didn’t say why it included OIS on the iPhone 6 Plus, but not on the iPhone 6, this may have something to do with the dimensions of the two handsets: the 5.5-inch model is 7.1mm-thin, while the 4.7-inch model is 6.9mm-thin.