The Daguerreotype

Cameras to take photographs have been used before the early 19th century, since the time of the Renaissance. In those ages a camera known as Camera Obscura was used to project images onto a paper which allowed to photographer to trace it.

Daguerreotype: 1839

Even though many people were working on various techniques for nearly 30 years, 1839, was the dawn of photographic history. Depending on how the light hit the camera, the highly reflective daguerreotype presented either a positive or negative appearance. People would have to pose for their portrait from five minutes to half an hour. This was due to the sensitivity of the photographic plates and the exposure time. The process involved coating a copper plate with silver nitrate which was then sensitized with iodine fumes. When the plate was exposed to light in a camera, it was then developed with mercury fumes and fixed with hyposulphite soda.

http://www.concordlibrary.org/scollect/Portrait_Exhibit/notes.html

http://www.phototree.com/history.htm

http://history1800s.about.com/od/photography/Photography.htm