For today's Through the Opera Glasses, I've got a definition for you from the world of film making.
All conventional films are shot following the 180° Rule.
"180° Rule - This is the rule which states that if two people are filmed in a sequence there is an invisible line between them and the camera should only be positioned anywhere within the 180 degrees on one side of the line. Crossing the line results in a certain particular jump, where it appears that the two people suddenly switched places." - Joel Schlemowitz, Glossary of Film Terms
Diagram illustration from Animatedbuzz
To show you how the 180° Rule works to give the viewers a sense of place where we can watch the events of the story unfold, here are three shots taken from Pedro Almodovar's Bad Education.
Here we have an establishing shot, which places us in a sports field and gives us our 180° line which joins the two boys in the center of the shot.
The next two shots are called shot reverse shot. They place one character in the sight line of the other, while staying on the same side of the invisible line.
This boy appeared in the establishing shot on the right side of the screen. Therefore, in a shot reverse shot sequence, he will remain on the right side of the screen.
In the second shot, the brown-shirted boy is actually in the center of the frame, but in the over-the-shoulder shot that follows, he remains on the right side. If this line is crossed by the filmmaker, it's very disorienting for the audience. The only time this would occur would be in an experimental film, or a film spoofing the 180° Rule on purpose.
Since breaking the line draws attention to the film as a film - which pulls the viewer out of the story - the decision to do this would be a stylistic one.
I'll be exploring more arts-related terminology subjects in future Through the Opera Glasses posts. Let me know if there's anything you've always wondered about, and I'll look into it for you.