Metalenses are ultrathin optical elements that can focus light using densely arranged subwavelength structures. Due to their minimal form factor, they have been considered promising for imaging applications that require extreme system size, weight, and power, such as in consumer electronics and remote sensing. However, as a major impediment prohibiting the wide adoption of the metalens technology, the aperture size, and consequently the imaging resolution, of a metalens are often limited by lithography processes that are not scalable. Here, we propose to adopt a synthetic aperture approach to alleviate the issue, and experimentally demonstrate that, assisted by computational reconstruction, a synthetic aperture metalens composed of multiple metalenses with relatively small aperture size can achieve an imaging resolution comparable to a conventional lens with an equivalent large aperture. We validate the concept via an outdoor imaging experiment performed with a synthetic aperture metalens-integrated near-infrared camera using natural sunlight for target illumination.