In 1839, Louis Daguerre announced his daguerreotype proces, after having experimented with capturing a permanent image for several years. The image, on a silver-plated highly-polished plate, emerged when the plate was immersed in mercury vapour. Daguerreotypes were images produced as direct positives on sensitised metal plates. The proces involved long exposure times and produced only one image. Despite the amazing detail, the delicate surfaces meant they had to be encased behind glas and it proved not to be a practical photographic method. This portrait camera for producing daguerrotypes was made by G Knight & Co, Philosophical Instrument Makers, 2 Foster Lane, London, around 1860.
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