Patent ID: 8218960
Filing Date: 2012-07-10
Classification: G02B,G03B

Abstract:
1. A lens apparatus comprising: an imaging optical system that includes a focus lens unit and that forms an image of a subject on an image pickup surface; a branching optical unit disposed at the image pickup surface side of the focus lens unit; a focus-state detecting unit that detects an out-of-focus amount or an amount equivalent to the out-of-focus amount by using light beams from the branching optical unit; an actuator that drives the focus lens unit in an optical axis direction of the focus lens unit; a controller that controls the actuator, in accordance with the out-of-focus amount or an amount equivalent to the out-of-focus amount from the focus-state detecting unit; a zoom optical system disposed between the focus lens unit and the branching optical unit, wherein the zoom optical system leads light from the focus lens unit to the branching optical unit; and an image-pickup-side-portion optical system disposed at the image pickup surface side of the branching optical unit, wherein the controller changes a drive amount by which the focus lens unit is driven by the actuator for every one out-of-focus amount or an amount equivalent to the out-of-focus amount of the focus-state detecting unit, in accordance with a zoom position of the zoom optical system; and further comprising an insertable-and-removable focal-length-changing optical system disposed at an image side of the branching optical system, wherein the drive amount is not changed when the focal-length-changing optical system is inserted or removed.