In the 1870s, a civil engineer devised early handheld cameras able to capture scenes with more detail than ever. He used the technology to document people on New York streets, from musicians to beggars to paperboys. The work of the innovator, often referred to as the ‘father of instantaneous photography’, has been compiled into a book by Erik Hesselberg called Candid New York: The Pioneering Photography of George Bradford Brainerd, out on 21 October
