The 180 Degree Rule

The 180 Degree Rule is a fundamental principle used by film makers to help to ensure that any action on the screen will be as clear and as easy to follow as possible.

The rule states that when something is occurring in a scene, an imaginary ‘action-line’ should be drawn between the two most important things in the shot, and the camera should always be situated on one side of that line.  If the camera is moved to provide a different angle on the action, it should always remain on the same side of the action-line. 

The action-line could be drawn, for example, between the heads of two people during a simple dialogue scene.  If there are multiple people in the scene, the action-line would be typically be drawn between those playing the most important roles at the time - in such cases it is therefore possible for the action-line to move between different people as needed, should the level of importance between the characters change.

The 180 Degree Rule isn’t only applied to people.  The action-line could be drawn between objects of interest also, for example between a dart player and a dart board.

The purpose of the 180 Degree Rule is to prevent confusion in the viewers who often need to quickly understand the layout of the scene and the positioning between characters or other important points of interest - even when the angle or type of shots is changed (for example, between close ups, medium, wide, at various angles etc.).

Taking the example of a simple dialogue scene between two characters who are facing one another as they talk, by following the 180 Degree Rule the film maker would ensure that the character on the left of the conversation will always be facing to the right (ie. towards the other character), and the character on the right of the conversation will always be facing to the left - regardless of camera angle or type of shot used.

Fig.1  This is the Master Shot.
Me on the Left looking at Evil-Me on the right.

Fig.2  This is a Mid-Shot.
Me looking to the right - at Evil-Me.

Fig.3  This is the Reverse-Shot (Close-Up).
Evil-Me looking to the left - at Me.

Figures 1, 2 and 3 look correct as the 180 Degree Rule has been followed.

If the rule is broken, and the camera is placed on the other side of the action-line (this is called “Crossing the Line”) it could easily become confusing to the viewer, and in the worst cases, it could look like the characters are looking away from each other (even if they were actually facing one another).

Fig.4  An example where the Rule has been broken!
In the top image I am looking to the right, however Evil-Me 
also appears to be looking to the right in the lower image.

It should be remembered however that although the 180 Degree Rule is a very helpful guideline, rules are there to be broken!  

A skilled film maker might decide to “Cross the Line” and break the 180 Degree Rule to produce a particular effect.  For example, the action-line could be deliberately crossed to create a sense of confusion or disorientation in situations where the film maker wants the viewer to feel unclear or uncertain about what is going on.