| 摘要 |
A motion-picture camera has a diaphragm whose aperture size is inversely proportional to the frequency fed to the diaphragm control servo-motor. This frequency is normally maintained between a predetermined upper limit and a predetermined lower limit. For fade out the frequency is rapidly decreased to the lower limit and thereafter regularly increased to the upper limit whereas for fade in the frequency is rapidly increased to the upper limit and thereafter regularly decreased to the lower limit. During rewind the frequency is maintained between the limits. This frequency increase and decrease can be effected by connecting oscillators of different frequency to the motor in a stepwise fashion, or by varying an impedance element of the tuned circuit of the oscillator that operates the diaphragm motor. Resistors and/or conductors strips on a control or program wheel can be used to carry out the fade out and fade in.
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