What does the black rectangle clipper when filming films and movies actually do? Why do they need one at all?

Question

I always wondered this

In: 133

Answer 1

The clap is to sync the audio to the footage and/or to sync footage together with itself, the words on the clapper tell the editor what take it is, or some other information to catalog and keep track of what was shot.

A lot of this is made redundant by cameras that capture audio, and the ability to name files whatever you want. Back in the destructive editing days they didn’t have these modern luxuries, they literally had to slice the film and splice it together. One wrong move and they could be fucked.