180-Degree Rule

What this is about

In planning, the rule turns into a drawing. Somebody sketches the two chairs, draws the axis between them and marks the half-circle where every camera position for that scene will live. From then on the wide, both over-the-shoulders and both singles come from the same side, and the audience keeps its bearings without noticing why. On the day, the script supervisor and the first AD are the ones who speak up when a position drifts across, usually before the operator has finished building it.

A term only helps when everyone on set means the same thing by it — so what follows is how it is used, not a dictionary definition.

What runs differently here

In planning terms, that means:

• The rule is the principle, crossing the line is the act of breaking it, screen direction is the consistency both are about.
• Three or more people create several axes at once, so the strongest relationship in the scene defines the working line.
• Moving subjects carry their axis with them, which is why a walk-and-talk needs the line redrawn whenever the pair turns.

With TillyGen

TillyGen groups the shots of a scene by camera side, so a position outside the working half-circle stands out in the plan.

Change one constraint and the consequences travel through the whole plan: affected shots are flagged, the call sheet is regenerated, and nobody keeps working from yesterday's version.