Dark camera
The camera obscura is an optical instrument that is black and makes it possible to obtain a flat projection of an external image onto the interior area of its surface. It was one of the ancient devices that led to the development of photography. Current photographic devices inherited the word camera from the old camera obscuras. It consists of a closed box and a small hole through which a minimum amount of light enters, projecting the image of the outside on the opposite wall. If it is provided with photographic paper it becomes a pinhole camera.
Originally, it consisted of a closed room whose only source of light was a small hole made in one of the walls, through which the light rays entered, reflecting the objects outside on one of its walls. The hole works like a converging lens and projects, on the opposite wall, the image of the outside inverted both vertically and horizontally.
Etymology
The name camera obscura (from the Latin camera obscura) was coined by Johannes Kepler in his treatise Ad Vitellionem Paralipomena of 1604. In it exposes the operation of the camera obscura, which will serve to develop the invention of the telescope.
In turn, the concept of "camera" in optics it was first introduced by the Muslim physicist and mathematician Alhacen, إبن الهيثم. This Arab scholar, born in Basra in 965, wrote the first optical treatise in which he demonstrated that the Greek theories about light rays were groundless and erroneous. Thus, in his book, he argued that light rays go from objects to the eye that observes them and not vice versa, as the Greeks Aristotle and Euclid had affirmed. He was the first to describe the principles of the "camera obscura", from Arabic, قمرة, should be read "comra", building a dark drawer with a small hole in one of its walls that, when crossed by a ray of light, it projected the image of the external object inverted. Precursor system of modern cameras.
History
Theories about the influence on prehistoric art and religious ceremonies
300,000 B.C. C. to 500 B.C. c
Although nothing is certain, there are theories that certain cave painting drawings could be inspired by the effects produced by the camera obscura. It is believed that the distortions in certain forms of animals in prehistoric art could be inspired by distortions produced on the surface when the projected image did not reproduce the angles exactly. Likewise, it has also come to be believed that the projections from the camera obscura may have played a role in Neolithic structures.
Perforated gnomons projecting images of the sun were described in the Chinese mathematical treatise Zhoubi Suanjing (1046 BC - 256 BC). The location of this circle of light could measure the time of day and year. In Arab and European cultures this invention was attributed much later to the astronomer and mathematician Ibn Yunus.
It is believed that ancient observations of gods and spirits, especially in prayer temples, may have been made from camera obscura projections.
Early Writings
500 BC C. to 500 d. c
The earliest writings of the camera obscura are found in the Chinese writings of Mozi's book dated to the 18th century IV a. C., attributed and named after Mozi, a Chinese philosopher and founder of Mohism. In these writings he explained how the inverted image at a 'collection point' or "treasure house"was inverted from an intersecting point that collected the light rays. The light coming from an illuminated person would be hidden under the hole on the one hand and on the upper part of the image on the other. The rays of the head (or top) would be on one side hidden above (just above the hole) and on the other on the bottom side of the image. This is an early description of the camera obscura: there are no other known examples dated before the 11th century.
The Greek philosopher Aristotle (384-322 B.C.) in the IV century B.C. C., or possibly a follower of his ideas, touched on the theme of the camera obscura in his work. A description of the apparatus and the phenomenon that gave it meaning is preserved from him:
"The sun's rays penetrating a closed box through a small, shapeless hole in one of its walls form an image on the opposite wall whose size increases with increasing distance between the walls in the one on which the hole has been made and the opposite wall on which the image is projected". The later observation of this phenomenon gave rise to Alhacén's theories.
Many Western philosophers and scientists wondered about this question before it was accepted that the circular shapes described in this "problem" they were actually projections in circular images of the sun. Although a projected image has the image of the aperture when the light source, aperture, or projection plane are close together, the projected image will have the shape of the light source when they are far apart.
Euclid has been credited with mentioning the phenomenon of the camera obscura as a demonstration that light travels in straight lines in his work Optics. However, in popular translations it is not found nothing that can be identified with the camera obscura.
Ignacio Danti added a description of the camera obscura in his annotated translation of 1573.
In the 4th century the Greek scholar Theon of Alexandria observed that: "Light from candles passing through a hole will create an illuminated spot on a screen that will be directly aligned with the opening and center of the screen. candle".
Experiments in the study of light
500 d. C. to 1100 AD c
In the VI century, the Byzantine Greek architect and mathematician Anthemius of Trales (most famous for being co-architect of Hagia Sophia) experimented with effects related to the camera obscura. Anthemius had a sophisticated conception of optics, as could be demonstrated in the light-ray diagram he constructed in AD 555. C.
In the IX century, Al-Kindi demonstrated that "light from the right side of a flame it will pass through the opening and end up on the left side of the screen, while the light coming from the left side of the flame will pass through the opening and end up projected on the right side of the screen".
In the X century, Yu Chao-Lung reportedly projected images of pagoda models through a small hole onto a screen to study the directions and divergences of light rays.
The Arab physicist Alhacén (965-1039) explained in his Book of Optics (1027) that light rays traveled in straight lines and were distinguished by the body that reflected those rays and wrote:
"The evidence that light and color are not mixed in the air or in transparent bodies is found in the fact that when numerous candles are in different locations within the same area and, when all of them look at a window that opens in a dark hole and when there is a white wall or opaque body in the dark looking at that window, the lights of those candles appear individually on that body or wall depending on the number of candles. Moreover, if one of the candles is covered, only the opposite light of the lock is extinguished, but if that darkness is elevated, the light will return."Alhacén, Book of Optics
Alhacén described the "camera obscura" and he made numerous experiments with small holes and light passing through them. The experiments consisted of three candles in a row and observing the effects on the wall after placing a gap between the candles and the wall.
"The image of the sun at the time of an eclipse, except when it is total, shows that when its light passes through a narrow and round hole and is cast into a plane opposite the hole it acquires the shape of a moon sickle. The image of the sun shows this peculiarity only when this sickle is very small. When the hole enlarges, the image changes, and the change increases with the added width. When the opening is very large, the image of the sickle disappears, and the light will appear round when the hole is round, square if the hole is square and if the shape of the opening is irregular, the light on the wall will acquire that same shape, as long as the hole is wide and the plane in which the light is projected is parallel to this."Alhacén, Book of Optics
Alhacén also analyzed the rays of sunlight and concluded that they created a conical shape where they met in the hole, forming an opposite conical shape on the opposite wall inside the darkroom. He is credited with saying about the camera obscura: "We did not invent this." His books on optics were influential in Europe beginning with Latin translations as early as the 1200s. Those he inspired include Witelo, John Peckham, Roger Bacon, Leonardo da Vinci, René Descartes, and Johannes Kepler.
In the book Essays on the Pond of Dreams, the Chinese scientist Shen Kuo (1031-1095), of the Song Dynasty, compared the focal point of a concave burning mirror and the "collected" hole of the camera obscura phenomenon with an oar on a pin to explain how the images were inverted:
"When a bird flies in the air, its shadow moves around the ground in the same direction. But if its image is gathered (like a tightening belt) over a small hole in a window, then the shadow moves in the opposite direction to that of the bird.[...] This is the same principle as the burning mirror.. This mirror has a concave surface and reflects a finger to give an upright image if the object is very close, but if the finger is moved further and further away there comes a point where the image disappears and after that the image is projected inverted. The point where the image disappears is like the hole in the window. That is why the oar is arranged and the oar at some point in its middle, constituting, when it moves, a type of "waist" and the handling of the oar will always be the reverse position of the finish (which is in the water)".
Shen Kuo also responded to a statement by Duan Chengshi in Various Bites of Youyang, written around 840, that the inverted image of a Chinese pagoda facing a shoreline was inverted because it was reflected by the sea: "This is nonsense. It is normal for the image to invert after passing through a small hole".
Optical and astronomical tools
1100 AD C. to 1400 d. c
The statistician and scholastic philosopher Roberto Grosseteste (c. 1175 - 9 October 1253) commented on the camera obscura.
In the 13th century, the English and Franciscan philosopher Roger Bacon was already aware of the phenomenon of the camera obscura, although, probably It was not until the XV century that it was given practical application as an auxiliary instrument for drawing. He falsely claimed in his De Multiplicatione Specerium (1267) that the image projected through a square aperture was round because the light would travel in spherical waves and thus assume its natural shape after passing through the hole.. He is also credited with a manuscript that advised studying solar eclipses carefully, watching the rays pass through round holes and studying the points of light they formed on the surfaces.
The image of a camera obscura with three light openings has also been attributed to Bacon, but the source of this attribution has not been given. A very similar image was found in Athanasius Kircher's Ars magna lucis et umbrae (1646).
The friar, theologian, physicist, mathematician and philosopher Witelo wrote about the camera obscura in his work Perspective (1270-1278), which was mainly based on the work of Ibn al-Haytham.
The archbishop and scholar John Peckham (1230-1292) wrote about the camera obscura in his works Tractatus de Perspectiva (1269-1277) and Perspectiva communis (1277- 79), falsely arguing that light gradually creates the circular shape after passing over an aperture. His writings were influenced by Roger Bacon.
At the end of the 13th century, Arnau de Villa Nova used a camera obscura to project live performances for entertainment.
The French astronomer Guillaume de Saint-Cloud suggested in his work Almanach Planetarum that the eccentricity of the sun could be determined with the camera obscura in an inversely proportional way between distances and the apparent solar diameters and the apogee and perigee.
The mathematician Al-Farisi (1267-1319) described in his 1309 work Kitab Tanqih al-Manazir (The Revision of Optics) how he experimented with a sphere of glass filled with water in a dark chamber with a controlled aperture, discovering that the colors of the rainbow were a phenomenon of the decomposition of light.
Judeo-French philosopher, mathematician, physicist, astronomer, and astrologer Levi ben Gershon (1288-1344) made numerous astronomical observations using a camera obscura with a Jacob's rod, describing methods for measuring angular diameters of the sun, moon, and planets bright Venus and Jupiter. He also determined the eccentricity of the sun based on his observations of the summer and winter solstices in 1334. Levi also noted how the size of the aperture determined the size of the projected image. He wrote about his discoveries in Hebrew in his treatise Sefer Milhamot Ha-Shem (The Wars of the Lord ), Book V, chapters 5 and 9.
First representations, lenses, visual aids and mirrors
1450 AD C. to 1600 AD c
The first complete and illustrated description of how the camera obscura works appears in the manuscripts of Leonardo da Vinci, the Italian polymath (1452-1519). Familiar with Alhacen's work in Latin translation and after extensive study of optical and human vision, he wrote the earliest known description of the camera obscura in mirror script in a notebook in 1502, later published in the Codex collection. Atlantic (translated from Latin).
"If the facade of a building, or place, or landscape is illuminated by the sun and a small hole is on the wall of a room in a building in front of this, which is not directly illuminated by the sun, all objects illuminated by the sun will send their images through this opening and will appear, from the other hand, on the wall facing the hole. These images will be recorded in a white paper, if placed vertically in the room not far from that opening, the objects mentioned above will be observed in this paper with their colors and natural shapes, but will appear in a small size and the other way around, due to the crossing of the rays in the opening of the wall. If these images were born in a sunlit site, they would appear on paper exactly as they are. The paper must be very thin and must be seen from behind."Leonardo da Vinci, Atlantic Code
This description, however, would not be known until Venturi published it in 1797.
Da Vinci was clearly interested in the camera obscura: over the years he drew around 270 diagrams of the camera obscura in his notebooks. He systematically experimented with various shapes and sizes of openings and with multiple openings (1, 2, 3, 4, 8, 16, 24, 28, and 32). He also compared the operation of the eye with that of the camera obscura and seemed especially interested in the ability to demonstrate basic principles of optics: the inversion of images through a hole or pupil, the non-interference of images, and the fact that the images were "all in all and all in every part".
The last known published drawing of a camera obscura was found in the book De Radio Astronomica et Geometrica, by physicist, mathematician, and instrument maker Regnier Gemma Frisius, in which she described and illustrated how she used the camera obscura to study solar eclipses on January 24, 1544.
Gerolamo Cardano, an Italian polythamian, described using a glass disk—probably a biconvex lens—in a camera obscura in his book De subtilitate, vol. I, Book IV. He suggested using them to observe "what happens on the street when the sun shines"; and he advised using a very white sheet of paper as a projection screen so that the colors would be realistic.
The Sicilian mathematician and astronomer Francesco Maurolico (1494-1575) answered Aristotle's problem about how sunlight shining through rectangular holes can form round points of light or points of increasing size during an eclipse in his treatise Photismi de lumini et umbra (1521-1554). However, this work was not published until 1611, when Johannes Kepler had already published similar discoveries on his account.
Italian polymath Giovanni Battista della Porta described the camera obscura, which he called "obscurum cubiculum", in 1558 in the first edition of his Magia Naturalis series of books. Battista suggested the use of a convex mirror to project the image onto a piece of paper and use this as a drawing aid. Della Porta compared the human eye to the camera obscura: "The image is shown to the eye through the eyeball as it is here through the window." The popularity of Della Porta's books helped spread awareness of the camera obscura.
In his 1567 work La pratica della perspettiva, Daniele Barbaro (1513-1570) described using the camera obscura with biconvex lenses as drawing aids and stressed that the image was more vivid if the lenses they were covered so much as to leave circles in the middle.
In his influential and meticulously annotated Latin edition of Al-Haytam and Witelo's works Opticae thesauru (1572), the German mathematician Friedrich Risner proposed a portable camera obscura drawing aid, a small light wooden shed with lenses on each of the four walls that would project the images of these onto a paper cube situated in the middle of this shed. Construction would take place with two wooden poles. Similar preparation was illustrated in Athanasius Kircher's 1645 work Ars Magna Lucis Et Umbrae.
Around 1575, the Dominican-Italian priest, mathematician, and cosmographer Ignacio Danti designed a camera obscura style and meridian line for the Basilica of Santa Maria Novella, and later had a gigantic gnomon built in the Basilica of San Petronio in Bologna. The gnomon was used to study the movements of the sun during the year and helped to determine the new Gregorian calendar, of which Dante was part of its elaboration, being part of the commission appointed by Gregory XIII and instituted in 1582.
In his 1585 work Diversarum Spectulationum Mathematicarum, the Venetian mathematician Giambattista Benedetti proposed the use of a mirror at a 45 degree angle to project the vertical image. This caused the image to be reversed, but would become common practice in later box-obscuras.
Giambattista della Porta added a "lenticular crystal" or binocular lenses to the description of the camera obscura in the second edition of Magia Naturallis , from 1589. He also described the use of the camera obscura to project scenes of hunting, banquets, battles, games or any desired thing in the streets. Small children and animals (for example, reindeer made of wood, wild bears, rhinos, elephants, and lions) could be part of the set. "They must appear by degrees, as if coming out of their caves, on the plane; the hunter must come with his masts, nets, arrows and other necessities that can represent the hunt; let there be horns, trumpets, trumpets blowing; those in the room will see trees, animals, hunters' faces, and all the rest so plainly that they will not know what is true from what are illusions. The sword drawings will shine inside the hole, which will make people almost scared," he said. Della Porta claimed to have shown these shows regularly to his friends. They admired him greatly and were seldom convinced by Della Porta's explanations that what they had seen was an optical trick.
1600 AD C. to 1650 AD c
The first use of the term "camera obscura" is found in the book Ad Vitellionem Paralipomena, by the German mathematician, astronomer, and astrologer Johannes Kepler. Kepler discovered the use of the camera obscura by recreating its principle with a book replacing a glossy book and sending threads from its edges through an opening in a table on the floor, where the threads recreated the shape of the book. He was also able to tell that the images were "painted on"; inverted and reversed on the retina of the eye and figured this was somehow corrected by the brain. In 1607, Kepler studied the sun in his camera obscura and observed a sunspot, but thought it was Mercury transiting across the sun. astro. In his 1611 work Dioptrice, Kepler described how the image projected from the camera obscura can be enhanced and reversed with a lens. It is believed that he later used a telescope with three lenses to reverse the image in the camera obscura.
When Germans David Fabricius and Johannes Fabricius (father and son) studied sunspots with a camera obscura, they realized that looking directly at the sun with a telescope could be harmful to your eyes. It is believed that they combined the telescope with the camera obscura, creating the camera obscura telescope.
In 1612 the Italian mathematician Benedetto Castelli wrote to his mentor, the Italian astronomer, physicist, engineer, philosopher, and mathematician Galileo Galilei about projecting images of the sun through a telescope (invented in 1608) to study the newly discovered Sunspots. Galilei wrote about Castelli's technique to the German Jesuit priest, physicist, and astronomer Christoph Scheiner.
From 1612 to at least 1630 Cristoph Scheiner would continue to study sunspots and build new telescopic solar projection systems. He would call these systems "Heliotropii telioscopi", later known as helioscopes. For the helioscope studies Scheiner built a box around the observation/projection end of the telescope, which can be considered the oldest known version of a box-type camera obscura. Scheiner also built a portable camera obscura.
In his 1613 work Opticorum Libri Sex, the Belgian Jesuit, mathematician, physicist and architect François d'Aguilon described how charlatans took money from people by claiming they knew necromancy and that they would raise the specters of the devil from hell to show them to the audience inside a dark room. The image of a wizard in the devil's mask was projected through glasses in the dark room, frightening ignorant onlookers.
By 1620, Kepler was using a portable camera obscura with a modified telescope to draw landscapes. This could be flipped to capture the surroundings in parts.
Dutch inventor Cornelius Drebbel is believed to have built a box-type camera obscura that corrected for inversion of the projected image. In 1622 he sold one to the Dutch poet, composer and diplomat Constantijn Huygens, who used it for painting and would recommend it to his artist friends. Huygens wrote the following to his parents:
"I have the other Drebbel instrument at home, which creates admirable effects in painting from the reflection in a dark room; It is impossible for me to express this beauty to you with words; all painting is dead in comparison, here is life itself or something higher if someone could articulate it like that. The figure, the contour and the movements come together naturally in an extremely pleasing style".
The German orientalist, mathematician, inventor, poet and bookseller Daniel Schwenter wrote in his book published in 1636 Deliciae Physico-Mathematicae about an instrument that a man from Pappenheim had shown him, which allowed movement of lenses to project more than one scene through the camera obscura.
In his 1637 work Dioptrique, the French philosopher, mathematician, and scientist René Descartes suggested placing an eye of a recently dead man (if one of these characteristics was not available, the eye of a fox) into an opening in a dark room and remove the skin back until one could see the inverted image formed on the retina.
The Italian Jesuit philosopher, mathematician, and astronomer Mario Bettinus wrote about the creation of a camera obscura with 12 holes in his work Apiria Universae Philosophiae Mathematicae (1642). When a soldier was placed in front of the camera, an army of 12 people doing the same movement would be projected as well.
French friar and mathematician Jean-François Niceron (1613-1646) wrote about the camera obscura with convex lenses. He explained how the camera obscura could be used by painters in order to acquire the perfect perspective in their work. He also complained about how charlatans abused the camera obscura to taunt viewers into believing the projections were magic or occult science. These writings were published in a version of La perspective curieuse (1652).
Use
The camera obscura was formerly used as an aid to drawing. The image, projected on paper or another support, could serve as a guideline for drawing on it. Later, when photosensitive materials were discovered, the camera obscura became a pinhole camera (the one that uses a simple hole as an objective).
These cameras were severely limited by the compromise required in setting the aperture diameter: small enough for the image to have acceptable definition; large enough so that the exposure time was not too long.
The use of the camera obscura was a major impetus for devising ways to produce permanent, automatic images. It can be considered as what provided the bases of what is known today as photography.
The camera obscura in painting
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Throughout history there have been painters, artists and scholars who used optical instruments such as the camera obscura to create their works. Two of the first to use this artifact in the field of painting were the German Albrecht Dürer and the Italian Leonardo da Vinci in the 15th and 16th centuries, with which they primarily drew the elements that were reflected in it. From that moment on, the camera obscura would be used as an auxiliary tool for painting and drawing, with its subsequent expansion throughout Europe. They would not only use the camera obscura, but they would also use other devices in the field of optics such as the camera lucida or convex mirrors in the case of romantic painters to project images onto canvas.
The camera obscura model used by Renaissance painters acquired the dimensions of a room, with the aim that the painter would enter it and be able to draw inside what was reflected from outside. For it to work, a translucent paper was placed on the back, in front of the hole through which the light entered, which had to be of reduced proportions to ensure that the image was formed correctly, otherwise it was impossible to obtain a detailed image and clear that would allow a representation close to the reality of things.
This theory that many renowned painters such as Van Eyck, Ingres, Velázquez, Caravaggio and Holbein used the camera obscura and different gadgets with lenses and mirrors to capture the smallest detail and achieve perfection in the line in their most realistic works, was maintained in 2001 by the painter David Hockney in his book Secret Knowledge, which caused much controversy in the world of research.
One of the artists that the author maintains made use of the camera obscura is the Baroque painter Johannes Vermeer:
"Resoluted to record exactly what I saw, Vermeer did not despise those mechanical advances that so ufana was his time. In many of his paintings are the exaggerated proportions of photography and the light is represented by those buns that are not seen at first sight but that appear on the viewer of some old cameras. There are those who think that I used the so-called 'dark shirt', which projects the image on a white sheet; but I imagine that I would look through a lens inside a box with a piece of broken glass squared, then painting exactly what I saw."David Hockney, Secret knowledge
Later, there is evidence of a sketch of another type of "transportable" camera obscura, made by Athanasius Kircher in the 19th century XVII, which is kept in the National Library of Paris and which he himself defines in his work Ars magna lucis et umbrae. This chamber was made up of an exterior cube of considerable dimensions to allow access and action by a person inside. It also had a lens on the two side walls and a prism was formed inside by means of transparent and stretched paper screens, where the painter captured the scenes projected from the outside. But this invention was never more than a sketch, because to be transportable the camera had to be light and firm enough to be carried, contrary to his popular idea of the "magic lantern", whose popularity grew. It would spread throughout Europe and end up being the germ of the cinematograph.
Another painter who is also credited with using optical instruments in the making of his works is the Renaissance artist Caravaggio during the century. XVI. A study presented by the International Studio Arts College of Florence points out that Caravaggio could have made his portraits in a dark room, illuminating his models through a hole in the roof, so that using a mirror and a lens, the projection of the image was produced. image on the canvas. Possibly, the painter fixed the image on the canvas exposing it to light for half an hour and with the application of substances sensitive to it, such as the mixture of carbonate powder and other chemical and mineral substances that were visible in the dark, which made it possible to carry out drawing in broad strokes.
There is also evidence that a camera of these characteristics has the name of the Venetian painter Canaletto engraved on it, dating from the 18th century, although it is not proven that it belonged to it. The use of the camera obscura would allow him to immortalize live the daily life of Venice, as well as its social contrasts; For this reason, he is considered one of the first precursors of experimentation with light in painting, since he used to access the highest places to capture the light effects of sunset and sunrise directly.
Velázquez was another of the painters to whom many theorists attribute the use of the camera obscura to make his most realistic portraits, specifically, to paint Las Meninas. He would have used this artifact to draw the general lines and perspectives on the large canvas following the projection of another earlier and smaller painting. This could have been done by reversing the operation of a booth-type camera obscura, illuminating its interior and leaving the room dark. This would make it possible to explain the precision in copying the straight lines and perspectives of the pictorial space from one painting to another, an accuracy that is very difficult to achieve freehand, but very possible by using the camera obscura.
In the eighties of the 20th century, the historian John Moffitt already maintained that the Sevillian painter could have used some technical mechanism that would have helped him to give his masterpiece more realism and to create the effect of confusion between the pictorial representation and reality. Experts recognized the possibility that this theory was true due to the discovery of glasses in the painter's studio.
Camera obscura and alchemy
The camera obscura, although it was created in response to the needs of painters and scientists, in ancient times it was known as the "magic box" and was closely related to a fantastic animal: the unicorn. Different writings and sketches have been found that describe the camera obscura, but that ensure that the hole and the effect of producing images that characterize it could only occur if the "box" with the unicorn's horn.
Since the IV century, magicians and alchemists investigated phenomena related to light and images. According to the Arthurian legend, Morgana, a court sorceress and Arthur's sister, jealous of Merlin's prestige, managed to steal the magician's secrets to try to use them, including the following writing: «(...) The eye of the magic box will have to be pierced with a unicorn horn; otherwise, it will be completely ineffective. (...)». This belief lasted until the 11th century and it was believed that unicorns became extinct because of the use to which their horns were put to order to use them as described above. With Merlin appears the first reference to this animal and his participation in the & # 34; art of learning images & # 34;.
Tzung Ching Pung, alchemist of the VI century, made this other reference: «(...) To get beautiful and delicate reproductions, both of forests and lakes, as well as anything else in general, it is necessary to have the horn of Ycung-*Kuo's unicorn (...)».
Abdel-el-Kamir does not describe the camera obscura like his fictional contemporary Merlin. However, he does give a recipe for how to prepare a light-sensitive emulsion; This is the photographic film. It was not until the XI century, with the alchemist Adojuhr, that the camera obscura (magical chamber according to him) was used for the first time. with an extraordinarily sensitive emulsion, which allowed him to print moving images using the lens.
Allusions to the unicorn in Arthurian legend and Tzung Ching Pung are vague; In Adojuhr's text the opposite happens, since a detailed and meticulous description of this animal is made. In addition, the usefulness of the horn of the different species for drilling the "objective" of the magic boxes. A transcription of Adojuhr is: «(...) A unicorn horn is taken, it is pointed at the tip and with it a small hole is made on any shining surface. All kinds of people, objects and places can be passed through this hole, compressing their essence, the same ones that will have to be carefully kept in a cardboard box where they will remain for all eternity, to be taken out when someone needs them (....)».
Another function that was also given to this magic box is to "capture evil spirits" and find a way to exterminate them; in the representations of the alchemist Adojuhr this use is seen more clearly. It was believed that there were different species of unicorns and each one was used in a different way in the magical boxes.
The camera obscura as a spectacle
Some camera obscuras were built as tourist attractions, but fewer and fewer of these remain. Some examples can be found in Grahamstown (South Africa), in Torre Tavira (Cádiz), Torre de los Perdigones (Seville), Villavicencio Palace (Jerez de la Frontera), Écija City Hall, Alameda Auditorium (Jaén), Torre del Ducal Palace of Béjar (Salamanca), Torre Monreal (Tudela), Peña Cabarga (Santander) and in Dumfries and Edinburgh (Scotland).