On large productions there is always a small crew set aside for shooting throw-away shots that do not justify the presence (or expense) of the principle crew. This is called the Second Unit. These guys go of to shoot establishing shots, pick-ups, and other miscellaneous shots that do not involve the cast. In many circumstances, they may be shooting at the same time as the principle crew, but at a different location. On very large productions, the Second Unit may also help out by shooting less important perspectives of logistically big scenes.