Your iPhone Photo App's Tap to Focus Feature
When composing your shots, you can take advantage of the Tap to Focus feature on your iPhone. Normally, the camera focuses on a subject in the center of the display, which you’re reminded of when you momentarily see a square appear in the middle of the screen.
But if you tap elsewhere in the frame, perhaps on the face of your kid in the background, the iPhone accordingly shifts its focus there, adjusting the exposure and what photographers refer to as the white balance. For another moment or so, you see a new, smaller square over your dog’s face.
If you want to lock the focus and exposure settings while taking a picture, press and hold your finger against the screen until the rectangle pulses. AE/AF Lock will appear on the screen. Tap the screen again to make AE/AF Lock disappear.
You can also exploit a feature known as HDR, or high dynamic range, photography. Tap the Options button to turn on HDR. The HDR feature takes three separate exposures and then blends them into a single image. In Settings (under Photos & Camera), you can choose to keep the normal photo along with your HDR result or just hang onto the latter.