1- Can you find image evidence of the tecnique?
2-when was it the first discovered and by whom?
3-how does this tecnique work?can you find and describe the processes needed to make it work? maybe illustrate how it is made?
4-what it is special about tecnique?
5-can you comment how important this tecnique has been for the history of photography. for example was it popular and is it still used today?
CAMERA OBSCURA:
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2- The first mention of a camera obscura was in 390BCE by Mo-Ti but was a greek philosopher Aristotle who understood the first principles.
he viewed the crescent shape of a partially eclipsed sun projected on the ground through the holes in a sieve, and the gaps between leaves on a plan tree.
3-To set up a camera obscura you need to go into a dark room, make a small hole in window cover and look at the opposite wall.
you are going to find the world upside down outside the window
4- The camera obscura is used for drawing and for in entertaiment and it was one of the invention to led to photography.
5- The camera obscura has been very important because it was the first step that led us to photography.
the last camera obscura it is been installed in 1994 in London, it is still used by professional photographers.
THE DAGUERRETYPE
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"L’Atelier de l'artiste. An 1837 daguerreotype by Daguerre, the first to complete the full process"
2- The daguerretype it was developed by Louis Daguerre together with his friend Joseph Nicephore Niepce in 1840
the image of daguerretype is formed by amalgam or alloy of mercury and silver.
3- the daguerreotype, along with the Tintype, is a photographic image allowing no direct transfer of the image onto another light-sensitive medium, as opposed to glass plate or paper negatives. Preparation of the plate prior to image exposure resulted in the formation of a layer of photo-sensitive silver halide, and exposure to a scene or image through a lens formed a latent image. The latent image was made visible, or "developed", by placing the exposed plate over a slightly heated (about 30°C / 90°F) cup of mercury. Daguerre was first to discover and publish (in the publication of the process and the English patent of 1839) the principle of latent image development.
The mercury vapour condensed on those places on the plate where the exposure light was most intense (highlights), and less so in darker areas of the image (shadows). This produced a picture in an amalgam, the mercury washing the silver out of the halides, solubilizing and amalgamating it into free silver particles which adhered to the exposed areas of the plate, leaving the unexposed silver halide ready to be removed by the fixing process. This resulted in the final unfixed image, which consisted of light and dark areas of grey amalgam on the plate. The developing box was constructed to allow inspection of the image through a yellow glass window to allow the photographer to determine when to stop development.
The next operation was to "fix" the photographic image permanently on the plate by dipping in a solution of hyposulphite of soda, often called "fixer" or "hypo", to dissolve the unexposed halides. Initially, Daguerre's process was to use a saturated salt solution for this step, but later adopted Hershel's suggestion of Sodium thiosulphate, as did W. H. F. Talbot.
The image produced by this method is extremely fragile and susceptible to damage when handled. Practically all daguerreotypes are protected from accidental damage by a glass-fronted enclosure. It was discovered by experiment that treating the plate with heated gold chloride both tones and strengthens the image, although it remains quite delicate and requires a well-sealed enclosure to protect against touch as well as oxidation of the fine silver deposits forming the blacks in the image. The best-preserved daguerreotypes dating from the 19th century are sealed in robust glass cases evacuated of air and filled with a chemically inert gas, typically nitrogen.
4- light reflects through the daguerrotype and bouncing through the back of it creating a 3D effect, you can only make one image of a daguerrotype.
5- The daguerrotype it is not used today.
COLOUR PHOTOGRAPHY
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" The first color photograph made by the three-color method suggested by James Clerk Maxwell in 1855, taken in 1861 by Thomas Sutton. The subject is a colored ribbon, usually but perhaps incorrectly described as a tartan ribbon."
2-Colour Photography was attempt around 1840.
early experiments were directed at finding a "chamaleon substance" wich assume the colour of the light falling on it.
Edmond Becquerel achieved better results but he couldn't find no way to preven the colour to fast fading when the image were exposed to the light.
the three-colour method was suggested 1855 by the scottish physicist James Clerk Maxwell.
it is based on the fact that the human eye sees the colour because its inner surface it is covered with millions of cells.
The first colour photograph made according to Maxwell's prescription, a set of three monochrome "colour separations," was taken by Thomas Sutton in 1861 for use in illustrating a lecture on colour by Maxwell, where it was shown in color by the triple projection method. The reproduction of a red-dyed ribbon and separation between blue and green ribbons were a mystery for decades, as the photographic materials of the time were almost completely insensitive to red light, and barely sensitive to green. Finally, in 1961, Evans showed that many red dyes also reflect ultraviolet light, coincidentally transmitted by Maxwell’s red filter, and surmised that the three images were probably composed of ultra-violet, blue-green, and blue wavelengths, respectively, rather than red, green, and blue.
3- Maxwell found that all the colors of nature could be counterfeited to the eye by mixing only three pure colors of light – red, green and blue – in proportions which would stimulate the three types of cells to the same degrees that the "real" colors did.
4- The special things about the colour photography is that the images seems more real.
5- The colour photography it was and it is very important.
Colour photography was very popular during the II World War, many pictures of war had been taked and the coloured pictures of Adolph Hitler and his empire are now part of our history.
Nowdays the colour photography has been replaced by the Digital Photography but many photographs find the colour photography more artistic and interesting than the digital photography.
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