FROM CAMERA OBSCURA TO THE DIGITAL PHOTO CAMERA. Codrua JALIU, Mircea NEAGOE, Daniela CIOBANU. Universitatea Transilvania din Braov

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1 UNIVERSITATEA TRANSILVANIA DIN BRA)OV Catedra Design de Produs +i Robotic, Simpozionul cu participare PRoiectarea ASIstatA de Calculator P R A S I C ' 02 Vol. III Design de Produs 7-8 Noiembrie Braov, România ISBN FROM CAMERA OBSCURA TO THE DIGITAL PHOTO CAMERA Codrua JALIU, Mircea NEAGOE, Daniela CIOBANU Universitatea Transilvania din Braov Abstract: The evolution and the improvements brought, during the time, to camera obscura in order to obtain a mechatronic product, the digital camera, are presented in the paper. The outlook is useful to the students and, also, to the designers in the field of photoproducts. Keywords: camera obscura, history, photo techniques, digital photo camera. 1. Introduction "Photography" is derived from the Greek words photos ("light") and graphein ("to draw"). The scientist Sir John F.W. Herschel first used this word in Photography is a method of recording images by the action of light, or related radiation, on a sensitive material. The process is based on a simple law of the physical world: light travels in a straight line and when some of the rays reflected from a bright subject pass through a small hole in thin material they cross and reform as an upside down image on a flat surface held parallel to the hole. This law of optics was known in ancient times. 2. About camera obscura The earliest mention of this device was by the Chinese philosopher Mo-Ti (5th century BC). He formally recorded the creation of an inverted image formed by light rays passing through a pinhole into a darkened room. He called this darkened room a "collecting place" or the "locked treasure room." Aristotle ( BC) understood the optical principle of the camera obscura. 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 of a plane tree. The tenth century Arabian scholar Alhazen of Basra had a portable tent room for solar observation and gave a full account of the principle. In 1490 Leonardo Da Vinci gave two clear descriptions of the camera obscura in his notebooks. In Fig. 1 is a cutaway view of the inside of a box camera obscura from the Saturday Magazine, 1838 and nearby - an exterior view of a wooden box camera obscura from an 1817 encyclopedia page. The image quality was improved with the addition of a convex lens into the aperture in the 16th century and the later addition of a mirror to reflect the image down onto a viewing surface. The introduction of the orbem e vitro, a kind of primitive biconvex lens, revolutionized the utility of the camera obscura. Like the lens that C.C. Harrison and J. Schinitzler would perfect in 1860, the orbem was constructed of two convex lenses. The design reduced distortion and increased clarity. Although no inventor is known, the lens was first mentioned by Girolamo Cardano, a Milanese mathematics professor, in the 1550 edition of his scientific encyclopedia. The term "camera obscura" was first used by the German astronomer Johannes Kepler in the early 17th century. He used it for astronomical applications and had a portable tent camera for surveying in Upper Austria. In 1572 Friedrich Risner constructed a small hut that could be carried around the countryside and

2 used to make topographical drawings. So, camera obscuras began to shrink in size and improve in optical quality. By 1657, camera obscuras were small enough to be carried under one arm. In 1685, Johann Zahn, a monk from Wurzburg, solved the final piece in the optical puzzle. He introduced lenses of longer and shorter focal lengths. Scenes as wide as a landscape or as close as a portrait could be viewed with a simple change of lens. He also painted the interior of his camera obscura black to avoid internal reflections. Excepting a mechanical shutter, Zahn's invention was the prototype for today's camera. By the beginning of the 19th century the camera obscura was ready with little or no modification to accept a sheet of light sensitive material to become the photographic camera. 3. On the history of photo techniques By the beginning of the 18th century at least four individuals were successful in making photos: Joseph Nicephore NIEPCE, Louis J. M. DAGUERRE, and Hippolyte BAYARD in France, and William Henry TALBOT in England. Each of them employed two scientific techniques that had been known for some time but had never before been successfully combined. The first of these techniques was optical. The second technique was chemical. The evolution in time of these techniques are presented in Figure 2. For the next decade Niepce struggled to perfect a primitive form of photo-lithography. He found a way to fix images using acid baths. In 1727, Johann Heinrich Schulze had discovered that certain chemicals, especially silver halides, turn dark when exposed to light. During the prior decades, a number of light-sensitive materials were tested to capture the image from the camera obscura, but the first successful permanent photograph is usually credited to Louis Daguerre. By 1837, after nearly a decade of trials, Daguerre devised a revolutionary type of image. He called it the Daguerreotype. In Figure 3 is presented the Daguerrotype sliding box cameras used by Daguerre (1840). Adhering a thin sheet of polished silver to a copper plate, he made it light sensitive by exposing it to the vapors from heated iodine crystals. Camera exposures of minutes were needed to make an impression. The latent image was fully developed by treating it with mercury vapor. Fixed in a solution of salt and hot water, the positive image became permanent. The Daguerreotype could only be seen in certain lights and from particular angles and could not be mass produced. Each image was singular and unique. Despite the drawbacks, Daguerreotypes offered images of extraordinary clarity and beauty. Daguerre officially unveiled his invention in That same year an Englishman named William Henry Fox Talbot announced the development of a process he called photography. William Talbot's greatest contribution was the introduction of the negative-positive process. He also pioneered the use of cheap and plentiful paper as a production medium. Talbot sought a chemical means to produce a permanent image. By 1835 he devised a simple method of making ordinary paper sensitive to light. He called it the calotype (Fig. 4). After dipping a sheet in a diluted salt solution, he dried it and then immersed it in silver nitrate solution. The resulting chemical combination formed light sensitive silver chloride. Placing the sheet in a camera, he exposed it for 30 minutes. The image was made permanent with a salt or potassium iodide bath. This process, though imperfect, washed away much of the unexposed silver chloride. Later, he switched to hypo sulfite of soda, or "hypo," as a fixer. This chemical is the direct ancestor of fixers used in contemporary photography. In contrast, Talbot's invention (1840), the CALOTYPE, produced a negative picture on paper; the lights of the image were recorded as darks, the darks as lights. A positive was made on another sheet of chemically sensitized paper, exposed to light through the negative. The photograph's capacity to repeat itself exactly and infinitely through the negative-to-positive process was one side of its radical character. By the 1850's both the Daguerre and Talbot processes were replaced by the wet plate process resulting from discoveries by Frederick Scott Archer in With this process, negatives were produced on glass plates and required shorter exposures than previous methods. The negatives could be placed against a black background to produce a direct positive photograph (collodion positives or ambrotypes) or used to make albumen prints. The collodion wet plates had to be exposed and developed while the plates were wet, before the surface hardened. This greatly restricted the mobility of the photographer, requiring considerable supportive supplies and equipment to be carried along with the camera. 4. On the consolidation of basis of modern photo techniques (19th and 20th century) A big improvement in photo camera evolution was the use of lens into camera obscura. In the XIX century, many inventors patented different kind of lens used in the photographic process:

3 1. in 1840 Joseph Petzval computes achromatic lens with an aperture of 1:3,6; in Figure 5 is presented a Metall- Portraitkamera with four element Petzval lens 1:3,7 ; 2. in 1843 W.F.H. Talbot claims patent for enlarging lens; 3. around 1845: N.P.Lerebours, Paris, uses turnable lenses with three different apertures; 4. in 1851 Ignazio Porro takes pictures with a "telephoto" lens and constructs a lens with variable apertures; 5. in 1860 J.H.Dallmeyer constructs the achromatic triplet lens; 6. in 1860 Harrison constructs the probably first wide angle lens with an angle of 73 degrees. Other improvements brought to the camera obscura during the XIX century are presented below: 1. in 1850, Marcus Sparling (England) constructs a field camera with ten wooden frames; 2. in 1853 J.M.Levy constructs a "moment" shutter; 3. in 1853 Thomas Ottewil constructs a folding camera (in Fig. 6 is presented a folding camera from 1890); 4. Lanet de Limenci introduces an extinction meter in the form of a camera (1856); 5. in 1857 C.G.Kinnear constructs a folding camera with konical bellows (Fig. 7); 6. in 1862 William England constructs a focal plane shutter; 7. in 1898 J.Poljakow constructs a camera with automatically controlled speed; around 1900 automatic self timer introduced (Autopose). The flashlight powder was invented in Germany in 1887 by Adolf Miethe and Johannes Gaedicke. Lycopodium powder (the waxy spores from club moss) was used in early flash powder. The first modern photoflash bulb or flashbulb was invented by Austrian, Paul Vierkotter. Vierkotter used magnesium-coated wire in an evacuated glass globe. Magnesium-coated wire was soon replaced by aluminum foil in oxygen. In 1930, the first commercially available photoflash bulb was patented by German, Johannes Ostermeier. These flashbulbs were named the Vacublitz. Stereo photographs were introduced in 1849 and became popular in Europe by 1854 and the U.S. by These consist of two photographs mounted side by side, showing the same subject from just slightly different perspectives, so that when viewed through a "stereoscope" the image appears three dimensional (Fig. 8). There were stereo daguerreotypes, ambrotypes, etc., but these are rare, the vast majority of surviving stereoviews being card mounted prints. The color photography. In 1861, James Clerk Maxwell, a Scottish inventor, showed that all color hues derive from three primary colors. Working with photographer T. Sutton, he projected three monochromatic slides of the Scottish flag from three different projectors. The combined images produced an exact color representation of the flag. Three negatives were required of the same subject. These negatives were converted into three layers of colored gelatin, and then carefully combined. The process was painstaking, time consuming, and demanded an arsenal of chemistry. In Figure 9 is presented the device used by Maxwell in his attempt. Eastman wanted to simplify photography and make it available to everyone. In 1883, Eastman announced film in rolls. George Eastman invented dry, transparent, and flexible, photographic film (rolled photography film) and the Kodak cameras that could use the new film in Pre-loaded with enough film for 100 exposures, the camera could easily be carried and handheld for operation. After exposure, the whole camera was returned to the company, where the film was developed, prints were made, new film was inserted, and then returned to the customer. Refinements like Thomas Dallmeyer's variable focus lens in 1899 helped make photography an ever more exacting science. In 1907, two Frenchmen, Auguste and Louis Lumiere, developed a simpler color photography system. The Lumiere brothers were pioneers in motion picture camera and projection systems, and they established the 35 mm standard still in use today. In 1924, documentary photography was revolutionized by the introduction of Leitz 24x36 mm camera, the Leica (Fig. 10). Utilizing 35 mm motion-picture stock, the camera was extremely portable and easy to use. The new type of camera gained favor among press photographers and eventually became the photojournalist's standard. In Figure 11 is presented the first spring motor camera, dating from Other technical innovations of this century include instant film (1928), Kodachrome color slide film (1935), and practical color negative photography in In 1947, Edwin Herbert Land introduced instant film, and patented the Polaroid camera (Fig. 12, a). In 1950, Kodak's Kodachrome film was widely marketed for the amateur photographer and in 1959 the zoom lens were

4 attached to the camera (Fig. 12, b). In 1960 the first photo camera with build-in electric motor drive (Fig. 12, c) and in 1964 the first camera with build-in electronic flash (Fig. 12, d) were produced. 5. On the digital camera Digital cameras capture images electronically and convert them into digital data that can be stored and manipulated by a computer. Like conventional cameras, digital cameras have a lens, aperture, and shutter, but they don't use film. When light passes through the lens it is focused on a photo-sensitive electronic chip called a charged coupling device (CCD). The CCD converts light impulses into electrical impulses (also called analog signal forms). The signals are fed into a microprocessor and transformed into digital information. This process is called digitization. In the mid 1970s, Kodak and other companies began investigating filmless technologies that could capture images with solid state circuitry. In 1986, Kodak succeeded in creating a sensor that could record 1.4 million picture elements, or megapixels. In the 1990s the first digital cameras appeared for commercial use. Kodak has offered a professional digital camera that is capable of storing an image with six million picture elements. Kodak has also introduced a camera capable of shifting between a macro lens, a 35mm lens, and a wide-angle panoramic lens with the push of a button. Although digital images do not yet match the quality of pictures produced on film, they represent an enormously flexible medium. Photographers are no longer limited by the physical properties of chemistry and optics. Computers outfitted with the appropriate software can transform images in ways never before imagined. A breakthrough occurred in 1951 when television cameras convert light waves into electronic impulses, and the video tape recorder records these impulses onto magnetic tape. Researchers at NASA's Jet Propulsion Laboratory developed ways to "clean" and enhance analog signals by processing them through computers. Signals were analyzed by a computer and converted into numerical or digital information. In this way, unwanted interference could be removed, while critical data could be enhanced. Digital cameras (Fig. 13) come in several formats designed for the specialized needs of photographers. They range from inexpensive snapshot models to sophisticated scanner backs that fit on professional large format film cameras. Regardless of their size or sophistication, all digital cameras operate in much the same way. All images we perceive are formed from optical light energy. Even digital images created within a computer are eventually converted into light energy that we can see. In order for a digital camera to store an optical image, it must be converted into digital information. A digital camera gathers light energy through a lens, and focuses it on a CCD which converts it into electrical impulses. These signals are fed into a microprocessor where they are sampled and transformed into digital information. This numerical data is then stored, and usually transferred later on to a computer where the image can be viewed and manipulated. After the CCD converts light into an electrical signal, it is sent to the image digitizer. The digitizer samples areas of light and shadow from across the image, breaking them into points or pixels. The pixels are next quantized assigned digital brightness values. For black-and-white, this means placing the pixel on a numerical scale that ranges from pure white to pure black. In color imaging, the process includes scales for color resolution and chromatic intensity. Each pixel is assigned an x,y coordinate that corresponds to its place and value in the optical image. The more pixels, the greater the image's range of tone. This quality is called spatial density, and is a vital component of image quality. How good a picture looks is also affected by optical resolution meaning the camera's optics and electronics. Together, spatial density and optical resolution determine the image's spatial resolution, its tonal spectrum and clarity of detail. In a digital photograph, each pixel has an assigned brightness value a luminous brightness that corresponds to a radiant intensity in the physical world. This value is determined by how many bits are in the quantizer. Making digital images in color requires an additional step. In black-and-white, the brightness resolution of a pixel is determined by one gray value. In color, that value has three components, one for each primary color, red, green or blue. This concept is called trichromacy. Color digital cameras are outfitted with three different sensors, each one sensitive to a primary waveband of light. After an image is scanned and quantized, it is further broken down into color values. Each pixel is assigned three color values which represent qualities of red, green or blue. Color values are further distinguished by their hue saturation and brightness.

5 6. Conclusions The further development of digital camera can not be conceived without a good knowledge both of the evolution of photo techniques and of trends of mechatronics, generally. The philo-genetic outlook presented in this paper is useful to the students and, also, to the designers in the field of photo products. References 1. Beaton, C., Buckland G. The Magic Image: The Genius of Photography from 1839 to the Present Day. Little Brown and Company, Boston, Gernsheim, H. The Origins of Photography. Thames and Hudson, New York, Pollack, P. The Picture History of Photography: From the Earliest Beginnings to the Present Day. Harry N. Abrams Inc., New York, Fig. 1 Fig. 2 Fig. 3 Fig. 4

6 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 a. b. c. d. Fig. 12 Fig. 13