| 摘要 |
<p>In an automatic focus control system for video cameras part of the object light is diverted through an optical sub-system (22) to a detecting unit (30) the output signals of which are used for controlling focusing of the optical main system. The output signals from the detecting unit are used for variably controlling a diaphragm (21) in the sub-system. The state of focus of the main optical system (2, 3, 4, 5 and 8) is sensed and depending on whether the main optical system is in considerably defocused state or approximately focused state, the effective diameter of the diaphragm (21) in the optical sub-system is reduced or enlarged, respectively. </p> |
