A lens apparatus mounted to a camera including an image-pickup element, including: a focus lens means movable in an optical axis direction for focusing; a zoom lens unit; a zoom detector; an aperture-stop device; a stop-value detector; a splitting optical unit; a focus-condition detection unit; an actuator; a controller for controlling the actuator based on an output from the focus-condition detection unit; and a manual operation member, wherein the controller obtains an F-number of the lens apparatus based on outputs from the zoom detector and stop-value detector and when the F-number exceeds a predetermined value, the controller causes the actuator to stop the focus lens unit so that the focus lens unit is driven by the manual operation member.