Use the mobile as a magnifying glass to read menu cards and the like without reading glasses. Start with the phone horizontally, the bottom right.

Unfortunately you cannot manually or by an app control the focus distance. Therefore the app uses autofocus, but when the nearest distance is detected, focus is frozen and the phone vibrates briefly. So start a piece away and move the phone closer and closer until it vibrates. Sometimes it is easiest with the light on, depending on the motif. Unfortunately this does not work on all phones, they will continue using autofocus.