A daguerreotype, invented and perfected by French scientist Louis Daguerre, was the first type of photograph to be successfully and commonly used. A plate sensitized with iodine is exposed to light (the image the photographer wishes to capture on film) and then later developed by pouring mercury on it. Each photo is considered unique and original but copies could be made by re-daguerreotyping a photo. Exposure time was long making the process almost impossible for portraits or else the image would appear blurry.
William Henry Fox Talbot invented another type of photography called a calotype. Unlike a daguerreotype which was its own individual image, a calotype created a negative in which endless amounts of “positives” – photographs – could be printed. A calotype uses silver iodide to capture the image and potassium bromide to fix it. This process was far more sensitive and therefore, produced a more specific image than a daguerreotype. The exposure time was far less, only 1-3 minutes making portraiture possible and practical.
-Cam
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