How does a movie clapperboard work?
If you have a video camcorder, then you are used to video and sound getting recorded on the same tape. The sound and video are always synchronized because they are recorded together in one place (See How VCRs Work for details). When filming a movie, the pictures and sound are recorded separately. The picture is recorded on film in the camera, and the sound gets recorded on a separate analog magnetic tape recorder (or, more recently, on digital tape such as a DAT tape). Because they are recorded on two different devices, you need a way to synchronize them. A clapperboard — the black and white board you are talking about– is the traditional way to handle the synchronization. The bottom of the clapperboard is normally a slate of some sort on which you can write the scene and take number. This information helps identify the shot during editing. Once the tape recorder and camera are rolling, the clapperboard operator places the clapperboard in front of the camera so
