Patent ID: 9684225
Date: 2017-06-20
CPC Classifications: G03B,H04N

Claim:
1. A lens unit that can be attached to and detached from an image-pickup apparatus, the lens unit comprising: an image-pickup optical system configured to form an optical image of an object, the image-pickup optical system including a variable-magnification lens configured to move in an optical axis direction and to change a focal length, and a focus lens configured to move in the optical axis direction for focusing and to correct a variation of an image plane associated with a magnification variation by the variable-magnification lens; a focus lens driver configured to drive the focus lens; and a controller configured to control the focus lens driver so as to maintain an in-focus state associated with the magnification variation, based on information on a tracking curve that represents an in-focus position of the focus lens corresponding to an object distance and the focal length of the image-pickup optical system, wherein the controller sends information on an actual position of the focus lens in a case the focus lens driver is not driving the focus lens based on the information on the tracking curve when the controller receives a transmission request for information on the in-focus position of the focus lens from the image-pickup apparatus, and wherein the controller sends information on a corrected position of the focus lens calculated by a difference between the actual position of the focus lens and the in-focus position of the focus lens indicated by the tracking curve in a case the focus lens driver is driving the focus lens based on the information on the tracking curve when the controller receives the transmission request for the information on the in-focus position of the focus lens from the image-pickup apparatus.