Originally, the term kinescope referred to the actual cathode ray tube (CRT) designed for early television sets, but it soon became synonymous with a process of filming live television shows for rebroadcasting. In the days before magnetic videotape, networks would assemble the cast of a television show in a studio in New York City and send out the live broadcast to affiliate stations in the Eastern and Central time zones. The problem was that stations in the Pacific time zone needed a three hour delay in order to show programs during evening hours. The solution was to use a 16mm or 35mm film camera to capture the images on the CRT and show the developed film three hours later. The film record of a live television show became known as a kinescope.
There were a number of technical issues which made the production of a kinescope less than ideal. One problem was similar to the situation a projectionist faced when showing silent films from the 1920s. A film camera captured images at a rate of approximately 24-30 frames per second. A CRT projected 50 or 60 "half images" per second, since the televised images were scanned in alternating lines across the screen. The solution was to synchronize the kinescope camera's frame speed with the scanning speed of the television monitor, a feat easier said than done. The images captured on a kinescope were often flickering and the actors' movements appeared jerky, much like a silent film shown at a higher frame speed.
Another technical issue surrounding the kinescope was the developing process. In order to make the air time of a West Coast feed, technicians would have to develop the film quickly and allow it to dry. The soundtrack would also have to be synchronized with the film, and the entire kinescope would have to be completely rewound and dried before it could be fed into a projector for broadcast. Because a kinescope was only intended to survive for a few broadcasts, it was not unusual to see reels of developed film sitting in the trash cans behind network studios. Many early television programs now considered to be classics were lost forever because of the fleeting nature of the kinescope process. Others are only represented by a few kinescopes that survived in private collections.
The introduction of magnetic videotape in the mid-1950s did not necessarily spell the end of the kinescope era. Smaller affiliate stations without videotape capability were still offered a kinescope of live network broadcasts. In fact, the practice of creating a kinescope of a television show for archival or rebroadcast purposes did not actually end until the late 1970s. Even magnetic videotape, the medium which replaced the kinescope in many television studios, is facing competition from newer digital storage mediums capable of producing high definition images. New processes for preserving and improving early kinescope recordings are also making it possible for new viewers to enjoy television shows such as Jackie Gleason's The Honeymooners and Sid Caesar's Your Show of Shows.