Preserve Camera Exposure Settings in iOS 15

In iOS 15, the native Camera app allows users to maintain manual exposure adjustments across app closures and system restarts through the "Preserve Settings" menu. By default, iOS resets exposure adjustments to automatic values whenever the Camera app is terminated to ensure a neutral baseline for subsequent shots. Enabling the specific configuration toggle instructs the operating system to write your chosen Exposure Value (EV) bias to persistent storage, ensuring your preferred brightness levels remain locked the next time you open the app.

How iOS 15 Retains Exposure Settings

When you close an app on iOS, its temporary state in RAM is cleared. By default, the Camera app purges manual sensor adjustments and re-engages Apple's automated computational photography pipeline (Smart HDR and auto-exposure).

To override this behavior, iOS 15 includes a dedicated persistence flag within the system configuration:

  1. System-Level State Persistence: When the "Exposure Adjustment" preserve setting is enabled, iOS writes the current EV offset to the app's persistent user preferences dictionary.
  2. App Launch Initialization: Upon launching, the Camera app queries this preference file during its initialization sequence. If the toggle is active, it applies the saved EV bias directly to the capture session configuration before the viewfinder displays a live feed.
  3. Indicator Persistence: The operating system also maintains the persistent exposure indicator (the small histogram or EV meter in the corner of the viewfinder), allowing you to see the exact offset currently applied without having to tap to refocus.

How to Enable Persistent Exposure

To keep your exposure settings from resetting after closing the Camera app or rebooting your iPhone running iOS 15:

  1. Open the Settings app on your iPhone.
  2. Scroll down and select Camera.
  3. Tap Preserve Settings.
  4. Toggle the switch next to Exposure Adjustment to the On position.

Once enabled, any manual adjustment made via the exposure slider in the Camera interface will stay in place until you manually reset it to zero, surviving app terminations, background memory purges, and device reboots.