Various kinds of low-light-level detectors and image intensifiers are described and specific charge-coupled device (CCD) developments are discussed from the perspective of the astronomical community, with possible application to optical microscopy. A number of research groups are reporting success at obtaining custom CCDs for application to high-quality cameras working at low-light levels. CCDs offer significant advantages in image quality and sensitivity compared with more traditional devices. Signal to noise (S/N) is derived for both CCDs and intensified devices. There is a tradeoff between the two and, because of the high read-out rate required by microscopists, intensified devices still offer a S/N advantage at the lowest light levels.