To reduce user’s concerns about their phones proper brightness, manufacturers use an environment light sensor for automatic brightness adjustment. This sensor measures light around the phone and adjusts display’s brightness. But sometimes it seems too interventive and applied changes are not correct. At the same time, some users want to set their device’s brightness as they wish. For example, some users prefer to lower the brightness in order to save battery life as much as possible. This is totally feasible and until iOS 10 there was a straightforward way to do it. But apparently, apple has decided to move mentioned setting in iOS 11 and put it in a deeper menu.
As you can see in above picture, Auto-Brightness option in iOS 10 (Left) that has been removed in iOS 11 (Right)
As you can see in the above pictures, this setting was in “Display & Brightness” menu until recently. This seems an obvious path for it, but where it has gone now?
In iOS 11 you have to go a longer path to find this option. In the Settings menu tap on “General” and then “Accessibility”.
Now tap on “Display Accommodations” to open its menu. In the new page, you can see “Auto-Brightness” option and enable/disable it as you wish.
As the hint below this option says, Turning off auto-brightness (and setting brightness at higher levels) may affect your device’ battery life, negatively. Hence, we recommend using it reasonably.