Microphone for sound cine camera - has slotted tube whose separation from microphone is altered according to objective focal length setting to vary directional response

摘要

The microphone is esp. designed for use with sound-film cameras. Its directional characteristic is varied in accordance with the focal length setting of the (zoom) lens. The control system comprises a slotted or damped tube (7) whose separation from a microphone capsule (8) is varied to alter the polar diagram of the microphone. An electro-optical sensor system (11, 12) comprises an array of light sources and detectors, provides a signal related to the polar response setting of the microphone. This signal is taken to a control unit (9). The control unit is connected to the motor drive which operates the zoom lens mechanism. The servo-system is therefore constructed so that for every setting of the camera's zoom lens, the "width" of the sound field detected by the microphone is adjusted accordingly.