الصورة السلبيـــــــــــة .. تاريخ التصوير الضوئي .. كتاب التصوير الضوئي

Negative Image.. History of Photography.. Book of Photography

Negative Image

The English mathematician William Henry Fox Talbot had been following the same research of Wedgwood, Niepce and Daguerre since 1833, but without knowing anything about their work. One day, while traveling on the shores of Lake Coom, he began to complain about not preserving the images given by the black room permanently. He later wrote: "How wonderful it would be to make this natural image self-imprinted on the paper!"

Based on his knowledge of the light sensitivity of silver salts, Fox Talbot began his research using paper coated with a solution of silver nitrogenate and table salt. He succeeded, as was the case with Wedgwood, in obtaining a negative image of natural objects after placing them on the paper. Then he obtained a positive image by reacting the sensitive paper through the negative image. At first, the paper was not sensitive enough to react within the room. However, by calibrating the proportions of salt and silver in the solution, he discovered that sodium chloride was an inhibitory and preventing agent. He prepared a paper coated with a solution of weak salts and rich in silver azotate and was able to obtain in 1835 a picture from his room in Lacoq Abbaye. This was the first negative drawing on paper. The picture was thus fixed and fixed in a concentrated solution of common salt.

At the same time, in Paris, the official Hippolyte Bayard was engaged in research with the aim of obtaining a direct positive image in the black room by using paper coated with silver chloride. He obtained his first picture in 1839, although he was ignorant of the works of Daguerre and Fox Talbot, as they were ignorant of his work.

From negative to positive image:

A calotype representing Fox Talbot's drawing workshop in Reading in 1845. The two positive images (above) come together to give a complete view of the scene (to the left) the inverted negative of the left part of the positive image.

The formation of the first negatives:

The world's first negative photograph was taken by Fox Talbot in 1835, representing a window from his house in Lacoq Abbey.

In early 1839 Fox Talbot wrote to Arago, demanding precedence over Daguerre's, and also exhibited examples of his fine drawings at the Royal Institution in London. In August of the same year, he exhibited 955 drawings of various objects and several positives and negatives taken by the camera noir. Unfortunately, Fox Talbot's method failed to attract the attention of the public, who preferred the images that could be obtained more quickly and accurately by the daguerreotype.
Fox Talbot intensified his research after being negatively affected by the lack of interest of the English public, taking into account French speculation. He was rewarded for his perseverance, as was the case with Niépce and Daguerre, by the accidental discovery of the slow photograph. He was able to obtain several views on paper

Fox Talbot:

A picture on wet collodion followed his discovery: the calotype.

Silver azotate and gallic acid sensitizer using a new machine made by the optician Andrew Ross (gallic acid has accelerating properties). Since the paper did not give any image, Talbot wanted to use it again by treating it again in a solution of gallic azotate so that he could display it again in the black room. How surprised he was when the image began to appear. He fixed it in a solution of potassium bromine and to this day photographers are amazed by the appearance of the magical image on white paper.

In 1841, Fox Talbot made some improvements to his method: his device was as fast as a daguerreotype and allowed for stops of less than 30 seconds. By using silver iodide on ordinary paper saturated with gallic azotate, the sensitive surface exposed to light could then be exposed by applying warm gallic azotate. Thus he obtained positive images by contact with the same sensitive substrate.

Fox Talbot was given a certificate for his invention, which he called "the wonderful one." The calotype was fixed with sodium persulphite, a substance whose proven properties had been known since 1819 by John Herschel. Talbot never mentioned the credit Herschel and Father J. B. Reid had given him in this field. Herschel, for his part, attacked Fox Talbot, describing his photographs as childish compared to those of Daguerre.

In 1844 Fox Talbot set up a photographic laboratory in Reading to meet sales orders and to answer the requests he received from people who wanted to use his principle at their own expense. Since then the speed of the calotype has increased, allowing for the taking of self-portraits. Talbot published a book entitled "The Pencil of Nature," the first illustrated book containing an explanation of his method. But this model (the calotype) never succeeded in the United States, where the daguerreotype was in the lead.

In 1842 several photographers opened a portrait laboratory in Great Britain. The most beautiful of these portraits was taken in Edinburgh by Robert Adamson, who had met the Scottish painter David Photo as a reference for his portraits. Together Adamson and Hill achieved the best portraits using the Fox Talbot method.

Daguerre died in 1851, a significant date as it ended a period of a new medium freed from the patented privileges of Daguerre and Talbot: the wet collodion technique of Frederick Scott Archie.

By this time the number of photographers had multiplied and photography had become ubiquitous.

Fox Talbot's invention: the calotype This photograph was taken by Adamson and Hill of Father James Vereen among the women fishermen in 1845.

The scientist who fixed the image:
The portrait of John Herschel taken by Julia Margaret Cameron in 1867. Herschel used to say that Talbot's photographs were childish compared to Daguerre's.

History of Photography

The Calotype:

It included a mount that could be turned and a simple lens that passed white light without distorting it. It was used in 1840 by Fox Talbot. The image was taken by means of a stopper and the sensitive paper was placed inside behind the device.