When choosing the right camera to suit your surveillance needs, you must determine whether you need a fixed lens or vari-focal lens. Vari-focal lenses allow for the manual adjusting of the camera view. There are adjustment screws/knobs at the camera that allow you to set the zoom and focus. This allows you to fine tune exactly how you want the camera set up. Fixed lenses do not allow for any adjustment. What you see is what you get. Hopefully this will help you make a decision when purchasing your security camera system.