Spirit photography

Spirit photography (or spiritual photography) is a mediumistic mode of photographic action that purports to record images of spiritual beings via chemically-treated plates, film, or electronically using an optical sensor. The practice was popular in the late nineteenth century, during the period when Spiritualism was in ascendancy and photography itself was still a relatively novel form in the public eye, falling into decline as mundane explanations for the effect were proposed and legal challenges brought negative publicity to the more famed of the practitioners (as in the case of William H. Mumler).