"Stop, moment!" - many people could subscribe to these words of J. V. Goethe. So you want to preserve for yourself a beautiful landscape or the image of a loved one, to perpetuate your appearance for posterity, and not everyone can master the art of painting. Came to the rescue "art of photography" - photography.
Photography is the acquisition of an image by exposing a light-sensitive material to light and storing it.
Even in ancient times, people noticed that light has a certain effect on some materials and objects: the human skin becomes dark in color from it, and some stones - opal and amethyst - sparkle.
The first who applied the properties of light in practice was the Arab scientist Algazen, who lived in the city of Basra in the 10th century. He noticed that if light enters a darkened room through a small hole, an inverted image appears on the wall. Alhazen used this phenomenon to observe a solar eclipse so as not to look directly at the sun. Roger Bacon, Guillaume de Saint-Cloud, and other scholars of the Middle Ages did the same.
Such a device is called "camera obscura". Leonardno da Vinci guessed to use it for sketching from nature. Later, portable cameras appeared, more complex, equipped with a mirror system. But until the 19th century, the maximum that such a camera allowed to do was to outline the projected image with a pencil.
The first to take the step towards image preservation was the German physicist J. G. Schulze. In 1725 he mixed nitric acid, containing a small amount of silver, with chalk. The resulting white mixture was darkened by sunlight. The researches of J. G. Schulze were continued by other scientists, and one of them, the Frenchman J. F. Niepce, managed to fix the image projected by the camera obscura onto a plate covered with a thin layer of asphalt. It took 8 hours to get the image, today such a photo would not suit anyone, but this was the very first photo. It was made in 1826 and was called "View from the Window". An important factor was the relief of the image on the etched asphalt, thanks to which the photograph could be replicated.
Somewhat later, compatriot J. F. Niepce, J. Daguerre, was able to obtain an image on a copper plate covered with a photosensitive material - silver iodide. After half an hour of exposure, the inventor treated the plate with mercury vapor in a dark room, and used table salt as a fixer. This method was called daguerreotype. The image was positive, i.e. black and white, but with the same shades of gray that match the colors. It was possible to shoot in this way only stationary objects, and it was impossible to replicate such pictures.
Much more convenient was the method invented by the English chemist W. Talbot - calotype. He used paper impregnated with silver chloride. The stronger the light acts on such paper, the darker it becomes, so a negative picture is obtained, and a positive picture is taken from it on the same paper. And you can make a lot of such positive prints! It was also important that W. Talbot achieved the exposure, which took a few minutes.
After U. Talbot's experiments, we can already talk about photography in its modern sense. This term was independently introduced by two scientists - the German I. Medler and the Englishman W. Herschel. In the future, both cameras and photographic materials were improved.
At the end of the 20th century, digital photography was born - a technology based not on chemical reactions involving silver salts, but on the transformation of light with a special light-sensitive matrix.
