1. An optical apparatus comprising: an imaging optical system including a correction optical system, which corrects an image blur, a zoom lens for changing a focal length, and a focus lens, which performs focus adjustment; an image capturing unit configured to capture an object image formed by said imaging optical system; a focal length detection unit configured to detect the focal length of said imaging optical system; an object distance detection unit configured to detect an object distance; a shake detection unit configured to detect shake; a walking shooting determination unit configured to determine whether or not a user of an apparatus is walking based on the shake detected by said shake detection unit; a sensitivity generation unit configured to generate sensitivity, which is the ratio of a moving amount of the object image on an image sensing plane to a moving amount of the correction optical system, based on a determination result by said walking shooting determination unit, the focal length, and the object distance; a correction amount calculation unit configured to calculate a correction amount based on the shake amount and the sensitivity; and a control unit configured to drive the correction optical system to correct the image blur based on the correction amount, wherein said sensitivity generation unit generates the sensitivity by limiting at least one of the object distance or the focal length, or a range of the sensitivity when said walking shooting determination unit determines that the user of the apparatus is walking.