A camera system has a camera with a photosensitive member that records optical images; and a lens apparatus removably mounted on the camera and forming an optical image with an image taking optical system including a focus lens. Focus control of the focus lens is changed in accordance the photosensitive member. A control circuit controls a lens driving unit and sets a driving pattern in accordance with information stored in a photosensitive member information storage circuit, and controls the lens driving unit based on focus adjustment state detected by a focus detection unit. An in-focus state can be achieved with focus accuracy suited for a photosensitive member in a combination of different cameras provided with different photosensitive members and interchangeable lenses common to these cameras.