| 摘要 |
PROBLEM TO BE SOLVED: To obtain a zoom lens capable of performing autofocusing by switching manual focusing, suitable for a high-performance video camera by finely vibrating the lens existing at the poststage of a focus part in an optical axis direction and moving the lens of the focus part in the optical axis direction based on optical image information associated with the fine vibration of the lens at the time of autofocusing. SOLUTION: The focus part consisting of a 1st positive lens group G1, a zoom part consisting of a 2nd negative lens group G2 and a 3rd lens group G3, and a master part consisting of a 4th positive lens group G4 and a 5th lens group G5 are disposed from an object side, and the focal distance of an entire system is changed by moving the 2nd and the 3rd lens groups G2 and G3 in the optical axis direction. At the time of manual focusing, a 1B-th lens group G1B is manually moved based on visual observation, and at the time of autofocusing, the 4th lens group G4 is finely vibrated in an axial direction, and the 1B-th lens group G1B is moved according to information based on the fluctuation of image quality due to the fine vibration thereof so as to correct the fluctuation of the position of the image surface caused with the change of an object distance. |
