A camera with a field of view that includes all, or nearly all, of the sky on one frame. The images from such cameras are circular, and have the zenith at the centre and the horizon around the edge. They are used in particular for meteor and fireball ‘patrols’. A simple design of all-sky camera consists of a convex mirror which reflects the image of the sky to a camera above it, pointing downward. More advanced designs use ultra-wide-angle lenses.