A camera is operated by right-clicking while holding it. This will display a camera reticule in the center of the screen and the amount of film the player has. Once the camera screen is visible, left-clicking while looking at a Pokémon (within a 20-block range) will cause the camera to take a photo of the Pokémon, producing a photo of the Pokémon and using up a piece of film. If the player's inventory is full when taking a photo, the photo will be lost and a piece of film will be wasted.
If the player does not have any film, the camera reticule will still be displayed, but no photos will be produced by the camera. Either right-clicking or left-clicking while not looking at a Pokémon will cause the camera reticule to disappear.