1. An automatic focus imaging system comprising: a lens unit; an image sensor; and a Micro-Electro Mechanical System (MEMS) unit comprising a substrate having a control circuitry, a reflective surface movably connected to the substrate, and at least one actuation unit comprising; a micro-actuator disposed on the substrate and driven by the control circuitry to have in-plane translation; and at least one micro-converter having a primary end, wherein the primary end of at least one of the at least one micro-converter is rotatably connected to the micro-actuator and the micro-actuator with the in-plane translation exerts a force on the primary end of the at least one of the at least one micro-converter, wherein the at least one micro-converter delivers the force to the reflective surface so that the reflective surface has a motion comprising out-of-translation; wherein the MEMS unit changes a distance between the lens unit and the image sensor by controlling the out-plane translation of the reflective surface in order to form in-focus mage on the image sensor, wherein the MEMS unit is fabricated by microfabrication technology to improve portability and focusing speed of the automatic focus imaging system.