7 Use the Exposure Lock
The iPhone’s camera will automatically set the focus and exposure for your shot. That’s great for shooting photos in a hurry, but it can quickly complicate video shots — particularly if it’s a video of one subject talking to the camera. It’ll keep readjusting and refocusing, which can lead to a distracting video.
Luckily, you can “lock” the exposure and focus in the native Camera app. When shooting a person talking to the camera, for example, just tap and hold on their face. You’ll see a box and a yellow bar with “AE/AF Lock” appear. Once it’s on, the iPhone will keep the focus and exposure consistent throughout the video.