1. The method of imaging a three-dimensional (3D) object that simultaneously accomplishes extended depth of field and 3D ranging, the method comprising the steps of: (a) providing an optical system including a waveplate, the waveplate constructed and arranged to modify the optical path of light from a 3D object such that optical system simultaneously produces an extended depth of field (EDF) image of the object and produces a depth-encoded image of the object having a point spread function (PSF) which varies according to range; (b) passing light from the 3D object through the optical system; (c) detecting the EDF image with a first detector and detecting the depth-encoded image with a second detector, the second detector spaced apart from the first detector; (d) digitally filtering the detected EDF image; and (e) producing a depth map from the detected encoded image.