You probably know that tapping once on the screen within the Camera app will cause the iPhone to automatically focus and adjust exposure to that region, but if you’re trying to take a picture with challenging lighting or depth conditions the auto adjustments are not always ideal. Instead, use focus and exposure lock to get the exact lighting and focus you want out of a picture:
- Open the Camera app as usual and aim it at whatever you want to take a picture of
- Tap and hold on the region of the screen where you want focus and exposure to be locked onto
- When “AE/EF Lock” appears on the bottom of the screen, the focus and lighting lock is set
You can take a picture right away, but once the lock is set you are free to move the camera around and the lighting and depth settings will stay the same. Tap elsewhere on the screen again at any time to release the AE/EF lock.
The end result of how pictures turn out can be dramatic, especially in situations where lighting matters. In the example picture up top, the left side shot is how the iPhone wanted to automatically set the lighting, and the right side shows the result of locking onto the lightbulb.
Auto-focus and auto-exposure can be stacked with zoom, and it should work on the newest iPad and iPod touch camera too.
Apr 27, 2012 osxdaily.com