Screen capture

When shooting from a movie screen, a satisfactory image quality can be obtained by synchronizing the shutters of a movie projector and a movie camera . The same applies to filming from a TV screen ^[1] . Otherwise, the image of a particular frame will be incomplete (partially overlapping by the shutters of the equipment) or will not be obtained at all. In professional conditions, this is carried out by mechanical (up to a direct connection of the pulling mechanisms of the projector and the movie camera) and electric methods.

Film enthusiasts often use simpler frame-by-frame shooting.

In the absence of synchronization, it is possible to obtain an acceptable high-quality photo image of a static scene by shooting with a shutter speed that is known to be greater than double the time it takes to display one frame. For example, at a standard projection frequency of 24 frames per second, the doubled display time of one frame is about 1/12 second, therefore, an acceptable shutter speed is 1/25 second.

Amateur cinema and video shooting from the movie theater screen are therefore divided into two main groups:

• "Screen" (CamRip) - shooting without accurate synchronization. If it is carried out on film, then the frame rate of such a copy is 8-12 frames per second. Since the brightness of the projection screen is approx. 30 cd / m², you have to use a highly sensitive film (250 or more units of GOST) and set the aperture to approx 2-2.8.
• “Telesync” is a synchronized survey in which the camera receives a signal from the projection equipment, which allows you to accurately determine the moment the projector shutter is fully open.

Currently used mainly for research purposes, thanks to:

• a significant difference in transmitting television tubes and matrices from film in spectral sensitivity . Of particular interest is the shooting in the infrared range of the spectrum, where the sensitivity of the targets of the vidicons and especially plumbicons is very high.
• significantly higher light sensitivity of transmitting television tubes and matrices, which allows you to shoot at extremely low light conditions (for example, in the case of observing the life of nocturnal animals).
• the small size and noiselessness of video cameras compared to the filming technique, which allows you to shoot in inaccessible places without disturbing the peace of the objects you shoot.

All this allows you to register processes on the film, the image of which is difficult to obtain directly or impossible. At the same time, direct shooting from the kinescope screen is practically not used: the obtained electronic image is printed on film by a film recorder .

Prior to the invention of the VCR in 1956, shooting from a kinescope screen onto a film was the only way to preserve a television image.

However, the low resolution of the television image and the problems of equipment synchronization make the application of this method very limited.

Amateur filming from the screen, without accurate synchronization, is feasible, as when shooting from a projection screen, with a reduced (up to 8-12 against 25) frame rate of the movie camera. However, some amateurs for this purpose received a television image on oscilloscopes with a long (about 0.2s) afterglow, thereby getting rid of dark stripes and at a normal shooting speed.

With the development of digital image recording systems and the cheapening of portable video recording equipment, the need for such a survey almost disappeared by the beginning of the 21st century .

• IT. Raev. Filming television images (rus.) // “World of Cinema Technique”: magazine. - 2008. - No. 10 . - S. 5-9 . - ISSN 1991-3400 .