Daguerreotypes and Calotypes
Louis Daguerre and Joseph Nicéphore Niépce (who was Daguerre's partner, but died before their invention was completed) invented the first practical photographic method, which was named the daguerreotype, in 1836. Daguerre coated a copper plate with silver, then treated it with iodine vapor to make it sensitive to light. The image was developed by mercury vapor and fixed with a strong solution of ordinary salt (sodium chloride). Henry Fox Talbot perfected a different process, the calotype, in 1840. Both used cameras that were little different from Zahn's model, with a sensitized plate or sheet of paper placed in front of the viewing screen to record the image. Focusing was generally via sliding boxes.
Read more about this topic: History Of The Camera