What exactly is that slate used for on movie sets?

Slate for Gamers: Hands of Fate

Returning from a month in Seattle where I was on set for 'The Gamers: Hands of Fate' (there will be a good, long write-up about that experience soon), one of the first tasks after taking a breather and checking in with people is to go through the logging process. And no, this isn't the kind that involves trees, smart-ass...seriously, that wasn't even a good joke. What's wrong with you? Go sit in the corner. As I was going through logging all of the clips from the green screen portion of the shoot, it occurred to me just how useful a good slate is, particularly in the editing room. On set it is someone's job, typically the second assistant camera or a production assistant, to "slate for the camera". This involves filling in the information on the slate itself (production name, camera angle, take number, director's name, which film reel is being used1), reading the information aloud once both the camera and audio are rolling, and then clapping the slate before getting out of frame. This is all for two purposes, one of which most people may already know about.

First of all, this marks a point both visually and audibly that can be easily recognized on both the video and sound files that can be used to sync the two together. Video and audio are recorded separately for movies, so this "clap" is there for the folk working in the editing room to use to line them both up.

Secondly, the information on the slate helps label the clip so that all of the post-production crew (which can range from one man to dozens to even hundreds on a Hollywood-scale production) can easily reference clips later.

The camera doesn't start rolling until the slate is on camera and in focus, so that the first frame of the video file has the slate's information visible and the editor doesn't have to scrub through to find it.

It varies from editor to editor (or if there's someone dedicated to the job of sorting and backing up the footage, it would be the job of the DIT, or the Digital Imaging Technician) but this clip could be labelled 'G3BD_Sc9A_Tk1.mov'. The prefix 'G3BD' is derived from the title 'Gamers 3' and the initials of the director to make it relevant only to this production. 'Sc9A' denotes the scene number from the script, and 'Tk1' indicates the take number.

It took me about 45 minutes to go through and change the name of each video file to it's proper reference within the After Effects project (see how much fun it can be?!), but now there'll be clear communication between the director, myself and others on which clip is which.

EDIT: As I've been reminded, it could also be used as an instrument of death in the right hands (say, Stephen Seagal?)

1 In the digital age a lot of the same film-specific terms still are applied. So a "reel" or "roll" actually refers to a memory card.