While third-party camera apps have allowed users to lock the focus and exposure of their shots for some time, the feature is a new one for users who prefer Apple’s built-in Camera app. Thankfully, the steps to enable it couldn’t be simpler.

Once you’ve decided on a subject you want to be in focus and properly exposed, simply tap and hold on its image in the viewfinder until the blue focus box pulses a few times. Once you let go, you’ll see “AE/AF Lock” on the screen, letting you know that your settings are locked in.
Disabling it is just as easy: simply tap anywhere in the viewfinder.