Astrophotography is the marriage of photography with astronomy. Long exposures on hyper-sensitized films show much that cannot be seen during real-time observation. Images of faint nebulae and galaxies can continue to improve during exposures ranging from several minutes to many hours, revealing detail that can't be seen without tremendous light amplification. Such photography requires excellent motorized mounts to correct for Earth's rotation, perfect alignment, and periodic correction during the exposures. In professional astronomy, and to a large extent in amateur astronomy too, photography has been superceded by digital imaging using CCD detectors and other electronic equipment.