Sir Arthur Conan Doyle with Spirit (1922), Photograph by Ada Emma Deane

The medium of photography arose at about the same time as mediums of a different sort -- the kind that claimed contact with the spirit world -- so it is not surprising that the two should intersect.  Spiritualism enjoyed a certain vogue starting in the mid-19th century, and it was not long before unscrupulous photographers began to capitalize on it.  Ghostly images were easy to produce, since exposure times were so long with early cameras that any movement by the subject would leave a blurred, transparent after-image on the photographic plates.  Photographers used a variety of tricks to superimpose spectral images onto portraits of live subjects.  A pioneering spirit photographer named William H. Mumler created a minor sensation by producing a portrait of Mary Todd Lincoln with a gauzy likeness of her dead husband standing behind her.  Sir Arthur Conan Doyle, who proved much more credulous than his fictional hero, Sherlock Holmes, posed for the portrait above, taken by a leading spirit photographer of the day, Ada Emma Deane.  Doyle, a stout defender of spiritualism, had lost two sons in the 1918 influenza epidemic and a brother-in-law in World War I and was desperate to make contact with them in the spirit world.