Using clapperboards in the film industry
This is not a toy
No matter where a movie is being shot, a version of the clapperboard is present on the set. This is not a toy but rather a carefully constructed device used in film production. Unlike using a video camcorder where audio and video are recorded on the same tape, filming a movie entails recording the video and the audio portions separately.
The action is recorded on film. The video is recorded on an analog (..oh the times!) or digital recorder. This material has to be synchronized. The information on the board helps in the synchronization process during editing. After the filming and recording begins an operator holds the board in front of the camera. The information on the board is read aloud. The clapper is then sounded. Matching the frame of the work with the information and the clapping sound on the recorder allows the two elements to be merged.
From wooden sticks to smart digital computers
More modern versions of the device have a pair of wooden sticks attached to an acrylic or whiteboard writing area that do not require additional light from the cameras to be seen. In recent years calibrated color stripes have replaced the traditional black and white. An electronic version known as a "smart slate" is becoming more widely used. Operators must take care that information is clearly legible and the clap is loud enough to be picked up by the external recorder.
A new digital version of clapperboard can do much more than just sound synchronization. They are capable of storing shoots details such as camera settings, optics and they can even use GPS data to find shooting location. You can get them for free for Android based devices or Apple.
Synching picture and sound
Traditional chalkboard clappers are made of wood and finished with special paint that allows writing with ordinary chalk. They are a combination of a chalkboard area that identifies information about the production and a hinged clap-stick used to help synchronize the sound and picture. The clap noise is easily identified on the audio track. Diagonal interleaved lines of black and white color on a sticks ensure clear visual of the board.
Roll camera... and action!
Typically the data on the device includes date, title, director's name, DoP (director of photography), producer and film company. The most important data is probably the scene and take number. This information helps identify the shot during editing. One of two popular systems is generally used. The major difference is in the order in which data is presented. The American system denotes scene number, camera angles and take number.
The European system records the slate number first and then a combination of the take number and camera angle. A letter is assigned to the camera shooting the information presented when more than one is being used. The script supervisor determines which system to use. The clapper loader is responsible for operating and maintaining the clapperboard. Sometimes a tail or end is filmed at the end of a take. The clapperboard is then held upside down.
This is how today's digital clapper works...
Digital domains superimpose an electronic version on the work. The sound recorder has a timecode generator that continually records the timecode on a special track of the tape. Showing the digital slate before the action starts allows the editor to synchronize picture and sound without the clapper. Because identifying each shot is extremely important in the editing process digital clapperboards do have a slate area.
The clapperboard may well be the most important part of any production. The synchronization that it allows improves the film production quality and speed, which in other terms means money. Without it movies would be far less enjoyable to make.