The archive will appear as part of the Fine Books, Atlases, Manuscripts and Photographs sale in London on November 12 with an estimate of £10,000-15,000.
Very little is known about Johnston, who came from a comfortable middle class Hampstead family - her father was a solicitor - and remained unmarried. Her photographs cover the years 1858-1864 and document the activities of her immediate circle and the many visitors to the family home, Manor House.
The roll call of sitters provides a vivid insight into 19th century intellectual suburban life (Hampstead did not become part of the County of London until 1889, although it had a good railway connection to the Capital via the North London Railway from the 1860s). William Wardell, the architect of St Mary's Cathedral in Sydney and St Patrick's in Melbourne; Frederick Edwards the geologist-palaeontologist; George Waterhouse curator at London Zoo, are just some of the figures who people Emma's photographs together with painters, diplomats and artists' models.
Bonhams Head of Books, Matthew Haley said: "Emma Johnston stands in a great tradition of Victorian women photographers. Unlike her famous contemporaries, Lady Hawarden, admired for her technical and artistic achievements and Julia Margaret Cameron, who gained recognition for her celebrity portraits, Emma was chiefly concerned with the daily round of her own social circle which may explain why this most talented of amateurs has been unjustly neglected."