You do need a camera. The trick is to look outside with the rifle, THEN come back to the room. This can be achieved by pressing the "S" key while in "shoot" mode (you can also use keys "A", "D", "W" and "S", to move your sights left, right up and down, respectively, in case you need to later. Coming back to the room will trigger the room to the left's lights to turn on, and THEN you have a reason to tear the wall apart to get that camera you seek.