| 摘要 |
PURPOSE:To obtain focus information so as to rapidly perform focusing in the case a rear focus type zoom lens is focused by a stepping motor. CONSTITUTION:As for the zoom lens consisting of four lens groups; in the case of moving the 2nd lens group L12 being a variable power lens and the 4th lens group L14 being a compensator lens on an optical axis by the stepping motors 11 and 12 respectively, the 4th lens group L14 is oscillated on the optical axis by the motor 12 with fine amplitude in a state where out-of-focus amount is small, and the 2nd lens group L12 is oscillated on the optical axis by the motor 11 with the fine amplitude in a state where the out-of-focus amount is large on a zoom telephoto side, so that the focus information is obtained based on an image signal obtained from an imaging device 15. |
