Several autofocus techniques are disclosed. The autofocus techniques help the device to achieve focus without presenting unpleasant blurred images to the operator of the camera, e.g., by dividing image frames into technical frames and display frames, with autofocus search occurring during technical frames. With another technique, the upper bound of the spatial frequencies of the blurred image permits a calculation of the focused lens position. Another technique searches for focus in jumps that exponentially decrease the search space with each jump. In another focusing technique, the lens is moved through a range of positions during a frame acquired with a rolling shutter exposure and the focused position may be determined from the sharpest row of the frame.