An ultra-small camera module with wide field of view includes (a) a wafer-level lens system for forming, on an image plane, an image of a wide field-of-view scene, wherein the wafer-level lens system includes (i) a distal planar surface positioned closest to the scene and no more than 2.5 millimeters away from the image plane in direction along optical axis of the wafer-level lens system, and (ii) a plurality of lens elements optically coupled in series along the optical axis, each of the lens elements having a curved surface, and (b) an image sensor mechanically coupled to the wafer-level lens system and including a rectangular array of photosensitive pixels, positioned at the image plane, for capturing the image, wherein cross section of the ultra-small camera module, orthogonal to the optical axis, is rectangular with side lengths no greater than 1.5 millimeters.