Title: Electronic control device for photographic exposure factors

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Abstract: A control device for an exposure factor of a photographic camera, such as the factor of shutter time or speed. A settable scale, settable to various values to control the exposure factor, is graduated logarithmically, and movement of the scale causes relative movement between a wiper or slider and a resistance serving as a potentiometer, the resistance of the potentiometer varying in a linear manner rather than logarithmically. The output of the potentiometer is connected to the input of a logarithmizer, the output of which is connected to a control element for controlling the exposure factor, the control being through an operational amplifier serving as an integrator, and through a threshold switch. An RC member associated with the amplifier is short circuited when the shutter is in its rest or closed position, the short circuit being interrupted at the beginning of the opening movement of the shutter. The movement of the shutter release to start the shutter exposure cycle serves to connect the apparatus to the source of current.


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