DGHHROTIPIA – Wikipedia

The dagherrotia It was the first photographic procedure for the development of images (however not reproducible). Developed by the French Louis Jacques Mandé Daguerre (from which he draws his name) from an idea by Joseph Nicéphore Niépce and the son of these, Isidore, was presented to the public in 1839 by the scientist François Arago, at the Académie des Sciences e The Académie des Beaux Arts.

after-content-x4 «Anyone who would have believed a few months ago that the light, being penetrated, intangible, imponderable, in short, without all the properties of the matter, would have assumed the task of the painter, properly drawing in itself, and with the most exquisite skill those ethereal images that ‘Ella Dianzi painted elusive in the dark chamber and that art tried in vain to arrest? Yet this miracle was fully operated in the hands of our Dagherre ”

( Macedonio Melloni, Report around the daguerrotype , 1839 )

The daguerrotype is obtained using a copper slab on which an electrolytically a silver layer has been applied, the latter sensitized in light with iodine vapors. The slab must therefore be exposed within an hour and for a period variable between 10 and 15 minutes.

The development takes place through mercury vapors at about 60 ° C, which make the areas previously exposed to light whitish. The final fixing is obtained with a solution of sodium girls, which eliminates the last residues of silver iodide.

The image obtained, the daguerrotype, is not reproducible and must be observed under a particular corner to reflect the light in an appropriate way. In addition, due to the rapid blackening of the silver and fragility of the slab, the daguerrotype was enclosed under glass, inside a box embellished with elegant brass, leather and velvet inlays, also aimed at underlining the value of the object e of the person depicted.

To reduce the exposure times and thus extend the field of application of the daguerrotype also to journalism, John Frederick Goddard used bromine vapors to increase the sensitivity of the slab, a result that also obtained Antoine Claudet but with chlorine vapors. However, also the union of these two techniques and brighter objectives did not allow an exhibition of less than ten seconds.
The use of mercury vapors made the production of daguerrotypes a process dangerous for health.

Original procedure of 1840 [ change | Modifica Wikitesto ]

Below, an extract from the file Il Daguerrotype , edition of 1840, on the procedure for the realization of a daguerrotype.

This process is divided into five operations. after-content-x4 The first consists in nectar and clean the lamina and make it its own to receive the sensitive layer. The second, in the application of this layer. The third, to submit the lamina prepared to receive the action of the light similar to receive the image of nature in the dark room. The fourth, in making this image appear which is not visible to his leaving the dark room. The fifth finally has the registry of removing the sensitive layer that would continue to be modified by the light and would necessarily tend to destroy the test entirely.

The camera for the daguerrotype was made up of a wooden box, a crack for the copper slab on the back and frontally a fixed objective, in glass and brass. The latter was initially built on the French ooctic scheme Charles Chevalier, owned a brightness between f/11 and f/16 and the focal length was 360mm. In 1840 Josef Petzval introduced a new four lenses and high brightness objective (f/3.7), which allowed the demolition of exposure times. Following the extreme interest aroused by the new technique, Daguerre, Niépce and A. Giroux founded a company for the production of the instrumentation necessary to obtain daguerrotypes.

The images formed on the slab as reflections, a feature that required the adoption of some precautions for the composition of the daguerrotype, such as the arrangement of the objects on the right to make them appear to the left, or not include the text, to avoid the reversal. In 1840 Alexandre S. Wolcott inserted a concave mirror at the bottom of the dark chamber, which reflecting the image for the second time, returns its correct positioning. Claudet contributed to the solution with a straightening prism after the goal.

In Italy the first specimen of Daguerre’s camera reached Alessandro Duroni’s optical laboratory shortly after the presentation of Arago. Some views of the city of Milan were taken with the new tool.

On October 8, 1839 in Turin, Enrico Federico Jest, together with his son Carlo Alessandro and with Antonio Rasetti, produced daguerrotypes using a self -produced machine, the first Italian photographic device; The first shot, now preserved at the Civic Gallery of Modern and Contemporary Art, resumed the Temple of the Gran Mother from the then Piazza Vittorio Emanuele I ^[first] . Thanks to the translation of the Daguerre manual by Jest himself, in 1840, numerous other studies are formed for the production of tools for daguerrotype.

The daguerrotype obtained a remarkable and quick success, allowing to faithfully reproduce the surrounding environment. At the beginning, the landscapes and the still lifes were predominant, mainly due to the long exposure times of exposure. With the reflecting of the procedure and the realization of bright objectives, portraits and some shy attempt at photojournalism grew.

The first experiment of daguerrotypy in Italy was held on September 2, 1839 in Florence with equipment produced by Giroux, but the technique also had immediate diffusion also in the city of medium size: for example, already in 1846 in Forlì the daguerrotypist Achille Manuzzi was famous, such as results from a speech by Aurelio Saffi ^[2] .

Despite this in Italy, the daguerrotype was used to a lesser extent compared to the popularity of which the process enjoyed in America. Production is also quantitatively lower than France and England. In Italy the photographic portrait established itself only from the years following 1855, with the collio cotton slabs and the cards prints of visits to the albumina. The only animal -subject daguerrotype made in Italy of which you are aware of is that of the elephant Frost owned by Vittorio Emanuele II (SIMEOM C4400 collection).

In Spain he landed on November 10, 1839, in Barcelona.

In America, the Dagherrupypy, already imported in 1839 by Samuel Morse and Francois Gouard, a pupil of Daguerre, achieved a large success. It was used to portray the members of the congress and the border territories with Canada, at the hands of Edward Anthony and five daguerrotypes made known the Niagara waterfalls in the world. At the London Universal Exhibition, the quality of American daguerrotypes gained three out of five medals on the United States.

In 1850 the first issue of the The Daguerreian journal devoted to the Daguerreian an photographic art , photography newspaper.

Since 1855, with the introduction of new techniques to humid collodion and albumin, the Dagherrupypia lost interest, even if used until the end of the century.

• Enrico federico is Il Daguerrotype , Rome, 1840
• Jean-A. Keim Short history of photography , Einaudi