Quoted from DiabloRush:It's my opinion the cameras do a fabulous job of deterring thieves. The lights go off, they see the camera, and they decide to pick an easier target. I've got this on video, many many times.
I completely agree. I installed motion activated high resolution cameras at every corner on my house that are all connected to a digital video recorder. The cameras are easily visible, since they are on every corner. I tell my neighbors that I think thieves will bypass my house and proceed to houses next door without cameras. Some people even install "Dummy" cameras for this very reason.