Hold your finger on the screen to lock focus
When you frame a shot with your iPhone, the camera will work its magic to set the focus automatically. This feature is useful, but it’s not perfect. If you want to ensure that the camera focuses on what you want it to, you’ll need to use the lock focus feature. Point your camera at your subject and press your finger on the area you want the camera to focus on. Hold your finger until the focus locks in place. You will see AE/AF Lock on the screen. Tap the shutter button to take a photo.
Manually adjust exposure
Although the iPhone features a fixed aperture, it’s still possible to manually adjust the exposure, which is basically a way of changing the ISO and shutter speed values. Unfortunately, there’s no individual control over such values, and you have to simply rely on an exposure slider.
To adjust exposure, tap to focus, and then slide up or down on the viewfinder. You’ll see the exposure slider move along with your swipes, and you’ll notice the image become overexposed, or underexposed, depending on which way you move the slider.
Get in close
Instead of relying on digital zoom, move closer to your subject. Not only will this let you capture objects up close, but it also lets you take advantage of the iPhone’s f/2.2 aperture. Getting in close and focusing on an object in the foreground or background creates a separation that allows for that shallow depth of field.
Use AE/AF lock
Instead of just tapping to focus, tap and hold on the viewfinder to lock the exposure and the focus. While locked, you can use the exposure slider to change exposure while maintaining a locked focus.