Photographic Historical Timeline 1841 The Calotype Process William Henry Fox Talbot A Negative Paper

Photographic Historical Timeline 1841 The Calotype Process William Henry Fox Talbot A Negative Image on Paper

Henry Fox Talbot had dedicated a considerable amount of time to developing his own method for capturing images using the camera obscura. In 1834, he conducted experiments involving the use of writing paper soaked in silver chloride, which he subsequently dried and exposed to sunlight beneath flat items like lace or leaves. Similar to Wedgwood's previous experiments, the silver salts darkened in areas where they were not shielded by the objects. However, Talbot made two significant advancements during this process.

To begin with, he found that the image's further darkening could be halted by immersing the paper in a potent salt solution. Furthermore, despite the initial negative nature of the image (with blacks appearing as whites, and so forth), he recognized the possibility of reproducing it by exposing another sheet of photosensitive paper to light, resulting in accurate tonal representation.

Miniature wooden cameras, containing sensitized paper, were constructed and strategically placed throughout his property at Lacock Abbey in Wiltshire. Achieving a recognizable image required exposure times ranging from 10 to 30 minutes.

The earliest extant photograph attributed to Henry Fox Talbot from this era bears the date 1835.

Talbot had various other pursuits and had not significantly advanced his photographic work when, in 1839, the initial reports of Louis Daguerre's photographic invention began circulating from Paris. Concerned that they might be working on similar processes, he hastily chose to disclose his own findings up to that point. Consequently, he prepared documents detailing his 'photogenic drawing' technique, which were presented to scholarly societies in London.

This publicity had a number of positive outcomes. Sir John Herschel, in particular, offered valuable advice. He recommended that hyposulphite of soda, now known as sodium thiosulphate, would serve as a superior fixing agent compared to salt. Furthermore, Herschel introduced key terminologies that became fundamental in photography: he proposed the use of 'negative' to describe Talbot's initial camera result, 'positive' for the final print with correct toning, and introduced the term 'photography' (literally, "light drawing") as a comprehensive term for chemically recorded images produced by cameras. Herschel's contributions played a crucial role in shaping the language and chemistry of early photography.

By 1840, Henry Fox Talbot had made significant advancements in his photographic process. He transitioned to using silver iodide and incorporated the use of a developer solution. These innovations allowed for shorter exposure times, making the photographic process more practical. Moreover, the images gained increased strength and quality through this post-exposure treatment.

In the subsequent year, 1841, Talbot secured a patent for his refined method and bestowed upon it the name "calotype process." This patented technique marked a pivotal moment in the history of photography, offering a more efficient and versatile approach to capturing images. The term calotype comes from the Ancient Greek καλός (kalos), "beautiful", and τύπος (tupos), "impression".