Shot reverse shot

The purpose for the shot reverse shot is to show two people in conversation and make the it look like they are looking at each other.The shot reverse shot often incorporates the 180 degree rule and the over the shoulder shot. This helps to show they are together in the same place at the same time. The camera will often be on Person A while he or she is talking and then switch to filming person B when he or she replies to person A.  However, it may also put the camera on parson B while person A is still talking to show person B's reactions and facial expressions to what is being said. 

If the people are filmed talking head on and then its all edited together, it does not look realistic and it may look like one person was not even in the room when the other was being filmed. However, the over the shoulder shot does not always have to be used, as long as the 180 degree rule is used and the person is filmed at an angle, the shot reverse shot can be used.  If person A is seen to be looking off screen and so is person B, it can look like they are in conversation to each other.

This diagram show how the people may bee seen on screen when using a shot reverse shot. The camera is not filming them face on.

This diagram shows the over the shoulder shot.

Here, i have taken screen shots from a short scene of Midsummer Murders. 

These two shots appear one after the other, the two people are in conversation and in the same room at the same time. This is shown using two over the shoulder shots. When it switches from on to the other, this is an example of shot reverse shot. 

These are the next two shots of the two charterers. Over the shoulder shots are not used but the 180 degree rule has been used (as in the shots before) and the angle of the camera added to the fact that both charterers are looking off screen helps to make it look like they are looking at each other. Once again the shot reverse shot is demonstrated here.