The camera feature is unlocked during Chapter 3 of The Amazing Spider-Man. Many elements of the game are revealed when you use the camera to take pictures, often unlocking game-related content. For example, taking pictures of enemies and NPCs (non-player characters) will unlock their biographies and 3D models. Some photos will reward you with experience points. You will also need to take pictures of several objects and characters in order to achieve 100% completion of the game.