What is a 180 degree rule and how to do it right?

The 180 degree rule exists in order not to confuse the viewer and not distract him from the story happening on the screen. An imaginary line is drawn between the two characters, which divides the scene into two parts. If the first frame of the scene is on the right side of the hero (camera A in the picture), then subsequent frames will also be on this side.

This is what it says in the textbooks; in practice, many directors break this rule to achieve interesting effects, such as tension, confusion, or a change in the dominant character controlling the situation. For example, if during interrogation a suspect begins to blackmail a detective, he becomes in charge. If initially the detective was in the right corner of the frame, and the suspect was on the left, then, thanks to the change in angle, the mood of the frame changes, and the characters change roles.

How to achieve this:

1. Make a gradual transition using Dolly or StadyCam, that is, smoothly move the camera from point A to point F. Such a gradual transition will not confuse the viewer and will let him know that the situation is changing in favor of the other character.

2. Make a sharp transition from camera B to D. There needs to be a good reason for this, because any viewer will notice such a change in shot. However, if you make this transition at the right moment, the viewer’s attention and tension will only increase. This is what Stanley Kubrick did in The Shining, for example.