Basic Filming Rules: 180 Degree Rule

When making a film, particularly when you're filming it, it's very important that you film in a correct way so when the audience is watching it back, it will make sense as to what they're viewing. One of the very important rules you have to follow when filming is the 180 degree rule.

The 180 degree rule is a basic guideline regarding the onscreen spatial relationship between a character and another character or object within a scene. An imaginary line called the axis connects two characters together. When they are facing each other so they are opposite each other, the axis (imaginary line is drawn straight through them). As filming this scene like when they are talking to each other for example, the camera will only be on one side of the imaginary line. So in one shot character 1 will appear on the left side of the screen and in a different shot, character 2 will appear on the right side of the screen. If the camera passes over the axis, this is called jumping the line or crossing the line. 

The 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 that scene. That shot can be used to orient the audience to the fact that we are looking at the scene from another angle. 

Here is a video demonstrating how cameras are used to film a scene using the 180 degree rule