Introduction to Carlo's photography

Invented by British scientist Henry Fox Talbot, he is also conducting his own experiment of recording images with black box. 1834, he soaked the writing paper in silver chloride, dried it, covered it with lace or leaves, and exposed it to the sun. As a result, like Wedgwood's experiment, all the silver salts that were not covered by objects turned black.

However, Talbot found two important improvement methods. First, soaking the exposed silver chloride paper in concentrated salt water can prevent the image from further blackening. Second, although the exposed image is a negative image (that is, the black part represents white and the white part represents black), he knows that the correct tone can be displayed by printing this negative image on another photosensitive paper with light. The oldest surviving photograph of Talbot was taken in 1835. At that time, carpenter L. Abbey made a small wooden black box for him and put photosensitive paper on it.

1840, Talbot improved his photography technique. He switched to silver iodide, and at the same time, he also used a developer, so that the exposure time was shorter, and the image was stronger through the post-processing in 184 1. He applied for a patent for the improved method and named it "Calotype process".