The microsphere optical nanoscopy (MONS) technique recently demonstrated the capability to break the optical diffraction limit with a microsphere size of 2-9 μm fused silica. We report that larger polystyrene microspheres of 30, 50 and 100 μm diameters can overcome the diffraction limit in optical imaging. The sub-diffraction features of a Blu-ray Disc and gold nano-patterned quartz were experimentally observed in air by coupling the microspheres with a standard optical microscope in the reflected light illumination mode. About six to eight times magnification was achieved using the MONS. The mechanism of the MONS was theoretically explained by considering the transformation of near-field evanescent waves into far-field propagating waves. The super-resolution imaging was demonstrated by experiments and theoretical simulations.