A method for controlling layer changes for an optical disk drive is provided, where a focus of a laserbeam emitted by a pickup head of the optical disk drive is moved from a current data layer of a disk to a target data layer of the disk. First, a position of a collimator lens of the pickup head is adjusted for spherical aberration correction. The objective lens is then lowered to a low position to move the focus of the laserbeam off the surface of the disk. The objective lens is then raised towards the disk. A focusing error signal is generated while the objective lens is being raised. Whether a target S-curve corresponding to the target data layer is present in the focusing error signal is then started to be detected. If the target S-curve is detected, the focus on operation on the target data layer of the disk is successful.