Night photography refers to photographs taken outoors between dusk and dawn. Night photographers generally have a choice between using artificial light or using a long exposure, exposing the scene for seconds or even minutes, in order to give the film enough time to capture a usable image, and to compensate for reciprocity failure. With the progress of high-speed films, higher-sensitivity digital image sensors, wide-aperture lenses, and the ever-greater power of urban lights, night photography is increasingly possible using available light.