| 摘要 |
PURPOSE:To make it possible to compact a varifocal lens and rapidly drive an image pickup means by detecting the position of a moving group to be moved on an optical axis back and forth to execute variable power operation and an image face position and moving the image pickup means to the image face position based upon these detected information to execute automatic focusing(AF). CONSTITUTION:The position of the 2nd lens component II to be moved on the optical axis back and forth to execute variable power operation is detected by a variator position detecting device 7, the detected position is inputted to a focal distance calculating circuit 13 and the calculated focal distance is sent to an AF arithmetic circuit 11. The circuit 11 calculates a variable or the like for moving the image pickup means 4 to drive the means 4. When the means 4 is moved to the image face position, the variation of the image face position due to variable power operation can be corrected. The whole length and weight of an optical system such as a varifocal lens can be sufficiently reduced, and at the time of executing AF by means of a video camera or the like, the image pickup means can be sufficiently rapidly driven. |
