Alan King filmmaker   I redirected Alan King filmmaker to this article The following is the entire text of the page when I redirected it Since it is completely unreferenced I decided to post it here instead of throwing it into the article Google turned up one result for the King Clapper device so its apparently not bogus but its a mailing list and therefore not a suitable source  Dorftrot   Film maker Alan King invented a piece of technology called The King Clapper A device which would act similarly to a clapper board by using a light that would simultaneously light up with an electronic beep that would be recorded on the sound track Only the sound recorder would hear this sound The advantage of this was that during the recording of observational documentaries in places like institutions eg A school or Hospital the film maker could provide a point in which to synchronize the image on the film with the sound recording taken without disturbing the subject or subjects during the time of filming Therefore allowing the film maker to stay as unnoticeable as possible whilst keeping as true to the concept of observational documentary as physically possible