You mean where the spot will be to take pics OF Diamondback? Because I'm pretty sure no one will be taking (legal) pictures ON the ride because of the camera policy. I would assume the Eiffel Tower will be a hot spot for shots of DBack, as well as directly under the initial drop and helix. It appears that one could get many good shots of the lift, drop, helix, splash, and woods from that one spot.
Don't forget the Crypt's exit walkway.