The prehistory of photography

We must go back to Aristotle (384-322 BC) to find the first references to a curious dark perforated box, which, through a small hole, allowed viewing, on its opposite wall, the inverse projection of external reality (stenoscope). In 1559, Jerônimo Cardan, an Italian mathematician and philosopher, improved this procedure by adding a glass lens and, thus, offering painters an instrument that allowed them to represent the world in three dimensions: the camera obscura.

Leonardo da Vinci was one of the first painters to use this instrument to paint. He used the camera obscura to capture the image of the objects or landscapes he wanted to draw. The image, when entering through the camera hole, was projected inversely onto the bottom of the camera, and the artist drew over what he saw. A mirror was placed to receive the light, and then the image that was previously inverted reached the bottom of the box in the correct position.

Note that, in Kircher's drawing (Figure 1), an artist positions himself inside the camera obscura capturing the luminous traces of a landscape projected onto his canvas by the optical phenomenon of light entering through the hole in the box. This was a technique used by several painters at the time. In the portable camera obscura designed by Brisson (Figure 2), we can follow the process of inversion of the image, when it enters the camera, and its reinversion when it is reflected by the mirror.

In Figures 1 and 2, the operation of a camera obscura is shown in illustration form. This is configured in a closed compartment, it can be an entire room, as in Figure 1, or a small box, as in Figure 2. The important thing is that in this compartment (room or box, for example) there is a hole, through which it passes light, entering the light rays that were in contact with the object. From the moment these rays enter the compartment, they form the image, on its opposite side, in an inverted manner. The important thing is that this compartment is completely sealed from light, allowing it to enter only through the hole.

With the camera obscura, there was the principle of image formation. The subsequent step was the search for fixing the images formed inside the camera obscura, which took place through the confluence of several researchers, who worked independently (BENJAMIN, 1994, p. 91).

With regard to the chemical process, the action of light on certain surfaces was already known many centuries ago, before Christ, by painters who had problems with color fixation. At the beginning of the 18th century, Johann Heinrich Schulze (1687-1744) demonstrated that silver salts react to the action of light.

If the 19th century is considered the century of countless inventions that established our living conditions, it is because it saw the advent of industrialization. Artisans no longer manufacture their objects for sale themselves, but enter, as salaried workers, in whose system the invention of machines allows large-scale manufacturing. The birth of capitalism and the market economy implies competitive competition: it is about producing at a lower cost. In this context, social turmoil will occur: the growth of the bourgeoisie (class that has money) and the proletarianization of artisans, who leave their communities to settle in cities, close to industries.

Painting had, until then, met the need to represent reality. The new requirements, both from an economic and social point of view, were to produce, in less time and at a lower cost, objects in an identical and perfect way. Therefore, photography responds to all these demands.

We know that inventions are the result of knowledge accumulated in various areas and, with photography, this process was no different. Optical and chemical knowledge existed for a long time, but it was necessary to group them together so that, in 1839, one of the greatest inventions of the 19th century could be made. Every invention is conditioned by the needs of society, and as the 19th century needed a rupture in the order of representations, photography was invented.

Discover some important dates and inventors, prior to what was officially considered the discovery of photography.

1725 — Johann Heinrich Schulze discovered that the darkening of silver salts occurred due to light and not heat.
1757 — John Dollond — English optician — built the first telescope lenses adapted to the camera obscura.
1777 — Karl Scheele discovered that ammonia acts as an image fixative.
1802 — Thomas Wedgwood obtained images using light on white leather impregnated with silver nitrate.
To see an image of an object through your camera obscura, choose a very sunny day. When outdoors, cover yourself with a black cloth, so that the side of the container with the hole faces the outside, pointing towards an object that is well lit. You will see the image inverted

of the object in front of you, either upside down or from left to right. This image will be seen in the same way that our eyes see it. However, we don't actually “see” like this, as the brain makes the conversion so that we see “everything as it is”.
The manufacture of a homemade camera obscura can be used as a learning tool in the classroom, so that the student better understands the relationship between images in our society and actually sees how images are formed, even with modern cameras.