This image was the view from Niépce’s estate, Le Gras. Produced onto a pewter plate using the light sensitive medium bitumen of Judea, this process took approximately eight hours of exposure in the sunlight. The original resides in the University of Texas, Austin. Although Niépce presented the technique of images on pewter to British scientists in the hopes of financial gain, it did not garner the support he had hoped.
In December of 1829 Niépce signed a partnership agreement with Louis Daguerre, but in July of 1833 Niépce died suddenly leaving his notes to Daguerre. While Daguerre really had no scientific background, he made two important discoveries that contributed to the development of photography. He found that if he exposed silver to an iodine vapour before exposing it to light, and then to mercury fumes after the picture was taken it would form a latent image. He then placed the plate in a salt bath which set the image. In January 1839 Daguerre announced his process and labelled it the daguerreotype. Polaroid still uses a similar process today for its photos.
Fox Talbot, upon reading of Daguerre’s invention, began perfecting his own process. In 1838 he received an effective fixer from John Herschel, the astronomer. Herschel showed that hyposulfite of soda (sodium thiosulfate) would dissolve silver salts. Talbot realized if he coated paper sheets with silver chloride, it created an intermediate negative image, which he called the calotype process. This negative image could then be used to reproduce a positive print, much like most chemical films today. George Eastman later improved this process by refining it and it is basically this technology used in film cameras today.