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Video assist (VA) is a system used in filmmaking which allows filmmakers to view a video version of a take immediately after it is filmed. Originally a small device, called the video tap, was installed inside a movie camera that allows (with the addition of a monitor) the director to see approximately the same view as the camera operator, and thus ensure that the film is being shot and framed as desired. This is done by using a small charge-coupled device (CCD) (similar to ones in consumer camcorders) inside the viewfinder. On modern film cameras, the assist is fed off a beam splitter, which splits the beam between the optical viewfinder and the video tap. The light enters through the lens, and hits the rotating mirror shutter, which bounces the light to the horizontal ground glass. The beam splitter is directly over the ground glass and turns the light again 90 degrees, and projects it onto the chip of the video assist camera—through its own lens system. The chip, together with its electronics, lens system and mounting hardware is the video tap, and was commonly called video assist until the video assist industry grew large. ==Modern video assist== Today, video assist is a name of a complex system, consisting of monitors, recorders, video transmitters, video printers, matrices and hundreds of yards of cables. The video assist crew—the video assist operators—are in charge of moving, operating, and troubleshooting the whole system which can easily fill a medium-sized truck. Their job is to run cables from all of the several cameras used on the show to a central location—often referred as the video village—where the director, DP, script supervisor, art director and several other crew members sit. When cameras are in unreachable locations, on the move, handheld, or steadicam-mounted, wireless transmitters are often used. All the camera connections coming into the video village go into the video trolley. These come in several shapes and sizes and are often hand-built by the operator based on his/her own preferences and the needs of the show. On the cart are the video recorders, the most important equipment of a VA op. The cart usually holds a video matrix, for making quick interconnections, several small operator's monitors, a video printer, all the wireless receivers, speakers, computers, laptops, digitizing boards, UPSes, and a bunch of small tools. The camera images are then fed to the larger monitors for the director, and sometimes for a second array of monitors for the producers, clients, etc. More often than not the Director and DP request a smaller, more private monitor set, and then the second array can be watched by everyone else. Video is often fed to make-up trucks, production trailers, or separate monitors around set for cuing stunts special effects of puppeteer On steadicam and remote head or crane operation, the viewfinder and beam splitter is often removed because its not needed. Then the full image is projected onto the video tap, making the image twice as bright, and hence better quality (lower noise). In these cases, even the camera operator uses a video monitor to operate the camera. Though the quality of the a video assist feed can vary greatly based on both the camera and the assist, it is always used as a guide and nothing more. Because the assist has its own controls for exposure, contrast, focus and color correction, it is not possible to use it to learn anything more than the frame lines. The video assist camera is usually significantly lower in resolution than the film camera as well, so critical focus is still usually determined by distance from the lens to the subject via a tape measure. Comedian and director Jerry Lewis is widely credited with inventing the precursor to this system,〔E.g., 〕 although some similar systems existed before Lewis first used a video camera to simultaneously record scenes alongside his film camera during production of ''The Bellboy'' in 1960.〔Glaskowsky, Peter. (Video assist predates Jerry Lewis 'patent' ), CNET, Accessed on July 28, 2011.〕 Director Blake Edwards was the first to use the beam-splitter single-camera system invented by engineer Jim Songer in the 1968 film ''The Party''.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Video assist」の詳細全文を読む スポンサード リンク
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