Security Cameras - A Help or a Boondoggle?

It was with some interest that we read Chuck Nevius's latest column on security cameras in the City. The reviews of the cameras have been mixed at best, with the most recent incident involving the use of camera footage to prove that an accused man was innocent, and that the witnesses in the case were somewhat less than reliable. On the other hand, the cameras have done very little to solve crimes, possibly because the footage quality is terrible, nobody watches them live, and the tapes are erased after seven days because of storage limitations. Limitations? When a 500 GB drive is under $100?

Our experience with the cameras in the Lower Haight has been, well, mixed. When they went up, one of the locals told us we couldn't take photos of the cameras. Not inspiring. On the other hand, nobody's been shot at Haight and Webster in some time. So...readers. Thoughts? Are they worth it? Is their presence preventative in some way? Or is this similar to the no-liquids rules at the airport - good theater, but fundamentally worthless?

Photo from Flickr user andreaskristensson, used under a Creative Commons license