Jane Martha St. John was an early English photographer. She is remembered for her calotypes of Rome and other towns in Italy, now in the J. Paul Getty Museum and the Metropolitan Museum of Art.
St. John made over 100 photographs in the late 1850s when travelling with her husband in Italy. Her introduction to photography probably resulted from the connections her privileged family enjoyed with John Dillwyn Llewelyn and the pioneering Talbots. St. John's work included portraits, travel views, and scenes of the grounds of houses. The photographs of the Hotel des Étrangers in Naples and the view of the waterfront are remarkable for the period. Unlike her contemporaries, she was interested above all in capturing the scenes of her travels but her images were also carefully composed. This is particularly evident in her photograph of the Roman Colosseum with the adjacent Arch of Constantine. Her individual approach to her work makes St. John one of the more interesting amateur photographers of the mid-19th century.