An optical system for a shallow form factor camera module comprises: seven even aspheric singlet lens elements formed of a molded plastics material, a flat image sensor, and a central aperture stop with at least 3 lens elements disposed in front of the aperture stop and at least 3 rear lens elements disposed between the aperture stop and the image sensor. The aperture stop has a pupil wide enough to provide at least f/1.0 aperture and the optical system has a total track length less than about 8.2 mm and a minimum spacing of about 0.6 mm between a surface of the rearmost lens element and an imaging plane of said image sensor. A magnitude of an aspheric coefficient for h4 of at least one surface of each of said rear lens elements is greater than 5×10−2.