As far back as the late 19th Century, photography - which was a relatively new technology at the time - was used as a tool with which to capture material, tangible evidence of the spirit world. It was a time when Spiritualism was very much on the rise and an increasing number of people were looking for some sort of sign that contact with the spirits of their lost loved ones was possible.
Many ghost photographs from this era were very similar and showed the bereaved individual with the ghostly visage of their deceased relative standing behind them in the background. Some spirit photographers also produced images of semi-transparent robed figures and other unidentifiable apparitions, either visible behind an unwitting subject or alone in an indoor setting.
Sadly, many mediums took advantage of the rise in popularity of such photographs by using fraudulent techniques such as double exposure to produce them on demand.
William H. Mumler
William H. Mumler is often credited with being the first spirit photographer, having discovered the art of creating a double exposure quite by accident when, while dabbling with amateur photography in his spare time, he took a picture of himself only to find that a second figure had appeared in the image.
Realizing the potential for financial gain from such photographs, he gave up working as a jewellery engraver and decided to offer his services as a full-time spiritualist medium. His unscrupulous repertoire involved taking photographs of a client and then producing a double exposure using a provided photograph of their deceased loved one. At the time (the 1860s) he was able to take advantage of the fact that a large number of people had recently lost relatives during the American Civil War, ensuring him a constant string of paying customers.
Among his more famous clientele was Mary Todd Lincoln - the widow of President Abraham Lincoln - who famously appeared as a spirit standing behind her in Mumler's photograph.
It proved a profitable, if not highly immoral ruse until Mumler became careless and started doctoring images of identifiable, living people into the photographs. Not surprisingly, someone eventually saw through this fraudulent practice and he ended up in court charged with fraud and larceny.
P. T. Barnum (subject of the musical 'The Greatest Showman') actually testified against Mumler at his trial. He hired Abraham Bogardus, a well known photographer of the time, to doctor a photograph of him being visited by the ghost of Abraham Lincoln as a way to demonstrate just how easily such images could be faked.
Surprisingly, the prosecution was unable to prove that Mumler had been faking the photographs and he was ultimately acquitted, however his career was left in ruins and his finances never recovered.
Over the decades that followed, several other spirit photographers rose to prominence and the field became the subject of numerous books and studies. Like Mumler, however, most of them employed similar photographic techniques to create fake images and many were exposed as frauds.
Among these was Frederick Hudson who in the 1870s became known as Britain's first spirit photographer. His photographs were not dissimilar to Mumler's and showed ghostly, robed figures super-imposed onto existing images using various fraudulent techniques.
One of his most famous clients was British naturalist and explorer Alfred Russel Wallace who was famous (though rarely acknowledged) for developing the theory of evolution through natural selection independently of Charles Darwin. When Hudson produced a double exposure showing Wallace's mother appearing beside him, the naturalist was convinced that it was the genuine article.
"I see no escape from the conclusion that some spiritual being, acquainted with my mother's various aspects during life, produced these recognisable impressions on the plate," he said at the time.
Despite this, many other public figures decried Hudson's work as fakery, even going so far as to accuse him of dressing up in robes to create the 'ghosts' that would appear in his images. The mechanics of his forgeries were well documented, even while he was still active.
Another well known figure in the spirit photography field was Britain's William Hope who began producing photographs showing alleged spirits in 1905. His methods were as dubious as those of Mummler and Hudson - again using double exposures to superimpose 'deceased' individuals into the shots.
In one notable case he produced a spirit photograph for physicist and chemist Sir William Crookes which showed his deceased wife, only for fellow physicist Sir Oliver Lodge to point out that the image of the spirit appeared to have been copied directly from a wedding anniversary photograph.
In 1920, Hope was exposed again when Edward Bush of the Society of Psychical Research sent him a photograph of a living person and claimed that it was his deceased son. When Bush attended a sitting with Hope, he was presented with a photograph containing a 'ghost' that happened to look identical to the person in the image he had sent earlier.
Another attempt to catch Hope out was made by paranormal investigator Harry Price during an experiment at the British College of Psychic Science. Price had secretly marked Hope's photographic plates with the logo for the Imperial Dry Plate Co. Ltd. so that it would appear on any images Hope produced during the experiment. When Hope got to work, his resulting ghost photographs contained no sign of the logo, suggesting that he had switched out the plates with some of his own containing pre-prepared images of spirits.
"William Hope has been found guilty of deliberately substituting his own plates for those of a sitter," Price wrote. "It implies that the medium brings to the sitting a duplicate slide and faked plates for fraudulent purposes."
The exposure of Hope and other fraudulent spirit photographers and mediums in the 1920s led to a mass resignation of 84 members of the Society for Psychical Research - an organization founded in the UK in 1882 to investigate and understand paranormal and psychic phenomena.
This exodus from the society was headed up by Sir Arthur Conan Doyle - author and creator of Sherlock Holmes - who had accused the society of adopting a more skeptical tone and being opposed to spiritualism.
By this time (1920s) classic spirit photography was well and truly on its way out.