What exactly is the 180-degree rule?

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I’m an aspiring cinematographer and have been attending film school for about a year. I’m still confused about what people refer to when mentioning the 180-degree rule. I have searched for what it refers to, but nothing gets me to comprehend it. Sorry for the stupid question, eli5?

In: 6

It just means that when cutting between two shots, you should not cut from facing one way to facing the complete opposite way, as it’s distorting to the viewer. When you do this is hard for the viewer to keep their bearings in what is where. Obviously, when done correctly and sparingly, breaking the rule can intentionally give the viewer a sense of confusion.

If you’re filming a scene where two characters are talking, imagine that there’s a line going through their heads. You don’t want to cross that line between edits.

This diagram does a good job showing what this looks like. https://upload.wikimedia.org/wikipedia/commons/thumb/b/be/180_degree_rule.svg/1200px-180_degree_rule.svg.png

You can cut from any of the angles on the right to any other angle on the right, but you don’t want to cut to one on the left. The reason is that crossing the line can be disorienting. If you’re imagine watching two people have a conversation in real life, you’ll be moving your head back and forth between them. The edit should mimic that. You never teleport to the other side of the table to look at the other person.

I was taught it was called screen direction. Basically, when you are putting a scene together, you can compose it of multiple angles, but all of those shots must be within a 180° angle of each other. This is so everything stays going in relatively the same direction.

Let’s say we have a scene that consists of a person walking down a road. If we start with a shot of them walking left to right, we don’t want any shots that would include them walking right to left (which would require the camera to move outside of that 180° arc). If we did include that shot of moving right to left, then it look as if the person turned around and started walking back where they came from.

You could also include left to right and right to left shots together, as long as you don’t mix moving toward the camera or away from the camera shots.

The best way to explain it is to see an example of the rule being broken. [Example at 0:11](https://youtu.be/QtyrqdK9wi0) the two people appear to switch places because the camera moves to the other side of them.

Of course this rule can sometimes be broken if you use it in such a way that fits thematically with what’s happening in the story. It also doesn’t need to persist throughout the whole scene, mostly just from shot to shot, you shouldn’t swing the camera more than 180°, but if you only operate within a single 180° arc, all of your shots can be rearranged in post production and it can be ensured that all shots can fit together without breaking the rule.

You might also hear this rule applied to setting up the camera before filming. You have frame rate, which is how many pictures or frames are captured in a second. Also shutter speed, which is how long the shutter is open and affects the light exposure to the sensor or the film. Most common frame rate is 24 frames per second as this mimics natural movement. It fools your brain basically. Any slower and your brain can tell it sees a series of pictures. At 24, your brain thinks it sees real movement. You want your shutter speed set to twice your frame rate. At 24 fps your frame rate is 1/48. Most digital cameras have a setting for 1/50, not 1/48. So with a 4K like we used in my intro course, you’d make sure you had everything set to 24fps and 1/48. Breaking this rule alters how the video looks. Faster shutter speed looks darker and there is very little motion blur. Slower shutter speed is lighter and makes the video look hazy or “dreamlike”.

Imagine you are making a video about someone high on drugs. From their point of view, everything is bright and lovely and kind of silly. From the point of view of someone watching them, they are deranged and maniacal. Best advice I was given was that if you have access to a camera then try out faster and slower speeds and faster and slower frame rates. See how they look at think about how they could be used to tell a story.