The dome camera is the least desirable form factor for any CCTV camera - at least any camera with an IR emitter. That's because it is common for IR light to reflect off the dome itself and cause issues. With a "turret" style camera, the camera lens and/or protective cover doesn't usually cover the IR emitters, so the IR isn't going to reflect back from the plastic covering. It might reflect back off something else in the environment, but dome cameras have that problem AND the self inflicted problem of the IR reflecting off the dome itself too.