The 180 Degrees Rule

Continuity Editing

What is it?

The 180 degree rule states that the camera(s) should remain the same side of an imaginary line/ The line is drawn perpendicular to the camera's viewpoint in the establishing shot of the scene. The rule enforces continuity of the film. An imaginary line called the axis connects the characters, and by keeping the camera on one side of this axis for every shot in the scene, the first character is always frame right of the second character, who is then always frame left of the first. The camera passing over the axis is called jumping the line or crossing the line; breaking the 180-degree rule by shooting on all sides is known as shooting in the round.

An example is that in a car chase, if the car is travelling from right to left, the next shot must also be shot from the same side, meaning the car has to enter the frame right to left again. The same applies for football matches and other sport. The image below portrays this and its basic example of how the line on action works:

Do not break the rule

The main aspect of the rule is to not break it. The only defense for breaking the rule is if it is used for effect. Otherwise, breaking the rule will only confuse the audience, especially if it is scenes within a chase, conversation or sport. 

The camera must always be on one side of the line.

The results of breaking the rule:

• Confusion
• Audience lose focus
• Become disorientated
• Miss vital parts of the film 

Eyeline match
Crossing the line when filming over the shoulder shots sifts the person's eye line, meaning that the actor's eye line's do not match. The two people should always be on the same side of frame in each shot.

As seen below, crossing the line makes it look like the actor is looking in the opposite direction and also a YouTube video that explains the basics of the eye line match rule:

Common usage, pitfalls and solutions

Screenshot of The Shining

Usage

The 180-degree rule enables the audience to visually connect with unseen movement happening around and behind the immediate subject and is important in the narration of battle scenes.

Pitfalls

The imaginary line allows viewers to orient themselves with the position and direction of action in a scene. If a shot following an earlier shot in a sequence is located on the opposite side of the 180-degree line, then it is called a "reverse cut." Reverse cuts disorient the viewer by presenting an opposing viewpoint of the action in a scene and consequently altering the perspective of the action and the spatial orientation established in the original shot.

Solutions

There are a variety of ways to avoid confusion related to crossing the line due to particular situations caused by actions or situations in a scene that would necessitate breaking the 180-degree line.

Screenshot of reverse angle from The Shining

Prevention

Either alter the movement in a scene, or set up the cameras on one side of the scene so that all the shots reflect the view from that side of the 180-degree line

Camera Arch move

One way to allow for crossing the line is to have several shots with the camera arching from one side of the line to the other during the scene. That shot can be used to orient the audience to the fact that we are looking at the scene from another angle. In the case of movement, if a character is seen walking into frame from behind on the left side walking towards a building corner on the right, as they walk around the corner of the building, the camera can catch them coming towards the camera on the other side of the building entering the frame from the left side and then walk straight at the camera and then exit the left side of the frame.

Can you get round the rule?

The only way around the rule without disorientating the audience is to show the camera movement. One the line has been crossed, and the movement shown, you have to stay on that particular side of the line, unless you show the movement back over it or are using the switch of this for a certain effect.

Here is a short example of it being used.