Say Cheese-- and Die Screaming! By R. L. Stine

GONE in a FLASH! A picture is worth a thousand screams-if it's taken with an evil camera that has a nasty vision of the future. Julie's future doesn't look pretty. And neither does anyone else's after they're caught in her lens! Things start looking up when Julie gets to HorrorLand. That is, until she starts falling down...into the Tunnel of Screams.