Using a film dolly

The dolly is one of the most famous tools of a filmmaker’s trade, used to move the camera in a shot. A studio dolly is a huge piece of equipment, normally heavy enough to hold the camera, camera operator and an assistant while pushed or pulled by a pair of grips. This is a vital piece of equipment in any large film and serves an important purpose but can be impossible to use for some filmmakers.

Advantages:

• Makes the shot more stable then if you were going to follow the actor with the camera free hand. 
• Makes movement with a tripod easier.