The Invention of Photography
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THE INVENTION OF PHOTOGRAPHY
Before the invention of photography, images were painted by artists or were duplicated by using printing plates. An image made by a painter was unique of its kind and copies of it could not be produced. Similarly, printing was done by hand and it required a lot of time and skill. The need remained for a process to be invented that could produce images of fine quality as well as to duplicate them. This was achieved in the 19th century with the invention of photography.
A photographic image requires 3 elements. A light source, a light tight box to capture an image, and a photosensitive material to preserve the image. A light source and a light tight box called the camera obscura was used for centuries as an artists aid to make drawings. Camera obscura was able to produce an image but the need remained of a process to preserve this image. Many scientists and camera obscura users underwent a number of experiments in this regard but failed to do so.
In 19th century a Frenchmen Joseph Niepce was able to capture and preserve the first photograph of history. His process involved exposing the image to a plate covered by bitumen of Judea, which hardens by light. The plate was then washed in lavender thus removing the soft unexposed parts. Niepce called his invention heliographs meaning sun drawings, which required eight hours of exposure.
Later in Paris Louis Jacques Mande Daguerre invented a similar process called daguerreotype. It involved the use of a silver plate sensitized by iodide and then exposing it in the camera obscura, and then the plate was kept on mercury solution and finally fixed by salt solution. The daguerreotype produced a much clearer picture than the previous heliograph and the exposure time was also reduced.
Although both these methods were similar but they had there negative points as well. First of all the image made was one of its kind and copies of it could not be made since the plate was exposed once. Secondly the daguerreotype could be viewed at certain angle. Now that the image was finally able to be preserved the need remained for a process so as to have multiple copies of it.
In England William Henry Fox Talbot was able to make negative of the image which could later be made positive and thus copies of it could be made. His process involved the making of a negative by exposing the salt and silver coated paper and then fixing it with a strong solution of salt. Then the negative was placed over a prepared sheet of paper and exposed to light thus a positive image