1. A camera, comprising: a spherically curved photosensor configured to capture light projected onto a concave surface of the photosensor; and a lens system configured to refract light from an object field located in front of the camera to form an image of the scene at a spherically curved image plane proximate to the concave surface of the photosensor; wherein effective focal length f of the lens system is within 20% of the radius of curvature of the photosensor, wherein the lens system is diffraction-limited over the entire image plane, and wherein chief rays of the lens system are substantially normal to the concave surface of the photosensor.