发明授权
US4443087A Focus state indicator 失效
焦点状态指示器

Focus state indicator
摘要:
A focus state indicator for a camera is provided such that the photographer may know a focus state in accordance with electrical signals respectively corresponding to the lens position in the previous focusing operation and a distance between a camera and a subject to be photographed. A circuit is arranged to generate a differential signal between the output electrical signals. The alarm operation of an alarm element is continuously changed between focused and out of focused states in accordance with the differential signal, so that the photographer can know the focus state.
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