Clapperboard

In the silent era the principal requirement of film stock identification during a day's shoot was the slate.

The slate displays the name of the production, the scene and "take" about to be performed, and similar information;[6] a camera assistant holds the clapperboard so the slate is in view of the cameras with the clapper sticks already open, speaks out information for the benefit of the audio recording, then snaps the sticks shut.

[7] Finding a way to synchronize visual and audio tracks was essential to traditional filmmaking because film stock reacts to light, not sound.

A modern clapperboard generally uses a pair of wooden sticks atop either a whiteboard or a translucent acrylic glass slate (the latter being easily legible via the light coming through it from the scene about to be shot).

The clapper sticks traditionally have diagonally interleaved lines of black and white to ensure the camera can capture a clear visual image of the clap in most lighting conditions.

The slate typically includes the date, the production title, the name of the director, the name of the director of photography (DoP) and the scene information — which follows two popular systems: A verbal identification of the numbers, known either as "voice slate" or "announcement", occurs after sound has reached speed.

Specific procedures vary depending on the nature of the production (documentary, television, feature, commercial, etc.

While these are usually fairly obvious once a system has been agreed upon, the script supervisor is usually considered the final arbiter in the event of an unclear situation.