2011年12月27日 星期二

Digital cameras

Digital cameras
Digital cameras differ from their analog predecessors primarily in that they do not use film, but capture and save photographs on digital memory cards or internal storage instead. Their low operating costs have relegated chemical cameras to niche markets. Digital cameras now include wireless communication capabilities (for example Wi-Fi or Bluetooth) to transfer, print or share photos, and are commonly found on mobile phones.

[edit] Early development

The concept of digitizing images on scanners, and the concept of digitizing video signals, predate the concept of making still pictures by digitizing signals from an array of discrete sensor elements. At Philips Labs. in New York, Edward Stupp, Pieter Cath and Zsolt Szilagyi filed for a patent on "All Solid State Radiation Imagers" on 6 September 1968 and constructed a flat-screen target for receiving and storing an optical image on a matrix composed of an array of photodiodes connected to a capacitor to form an array of two terminal devices connected in rows and columns. Their US patent was granted on 10 November 1970.[11] Texas Instruments engineer Willis Adcock designed a filmless camera that was not digital and applied for a patent in 1972, but it is not known whether it was ever built.[12] The first recorded attempt at building a digital camera was in 1975 by Steven Sasson, an engineer at Eastman Kodak.[13][14] It used the then-new solid-state CCD image sensor chips developed by Fairchild Semiconductor in 1973.[15] The camera weighed 8 pounds (3.6 kg), recorded black and white images to a cassette tape, had a resolution of 0.01 megapixels (10,000 pixels), and took 23 seconds to capture its first image in December 1975. The prototype camera was a technical exercise, not intended for production.

[edit] Analog electronic cameras

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Main article: Still video camera
 
Sony Mavica, 1981
Handheld electronic cameras, in the sense of a device meant to be carried and used like a handheld film camera, appeared in 1981 with the demonstration of the Sony Mavica (Magnetic Video Camera). This is not to be confused with the later cameras by Sony that also bore the Mavica name. This was an analog camera, in that it recorded pixel signals continuously, as videotape machines did, without converting them to discrete levels; it recorded television-like signals to a 2 × 2 inch "video floppy".[16] In essence it was a video movie camera that recorded single frames, 50 per disk in field mode and 25 per disk in frame mode. The image quality was considered equal to that of then-current televisions.

 
Canon RC-701, 1986
Analog electronic cameras do not appear to have reached the market until 1986 with the Canon RC-701. Canon demonstrated a prototype of this model at the 1984 Summer Olympics, printing the images in the Yomiuri Shimbun, a Japanese newspaper. In the United States, the first publication to use these cameras for real reportage was USA Today, in its coverage of World Series baseball. Several factors held back the widespread adoption of analog cameras; the cost (upwards of $20,000), poor image quality compared to film, and the lack of quality affordable printers. Capturing and printing an image originally required access to equipment such as a frame grabber, which was beyond the reach of the average consumer. The "video floppy" disks later had several reader devices available for viewing on a screen, but were never standardized as a computer drive.
The early adopters tended to be in the news media, where the cost was negated by the utility and the ability to transmit images by telephone lines. The poor image quality was offset by the low resolution of newspaper graphics. This capability to transmit images without a satellite link was useful during the Tiananmen Square protests of 1989 and the first Gulf War in 1991.
US government agencies also took a strong interest in the still video concept, notably the US Navy for use as a real time air-to-sea surveillance system.
The first analog electronic camera marketed to consumers may have been the Canon RC-250 Xapshot in 1988. A notable analog camera produced the same year was the Nikon QV-1000C, designed as a press camera and not offered for sale to general users, which sold only a few hundred units. It recorded images in greyscale, and the quality in newspaper print was equal to film cameras. In appearance it closely resembled a modern digital single-lens reflex camera. Images were stored on video floppy disks.
Silicon Film, a proposed digital sensor cartridge for film cameras that would allow 35 mm cameras to take digital photographs without modification was announced in late 1998. Silicon Film was to work like a roll of 35 mm film, with a 1.3 megapixel sensor behind the lens and a battery and storage unit fitting in the film holder in the camera. The product, which was never released, became increasingly obsolete due to improvements in digital camera technology and affordability. Silicon Films' parent company filed for bankruptcy in 2001.[17]

[edit] The arrival of true digital cameras

 
Nikon D1, 1999
The first true digital camera that recorded images as a computerized file was likely the Fuji DS-1P of 1988, which recorded to a 16 MB internal memory card that used a battery to keep the data in memory. This camera was never marketed in the United States, and has not been confirmed to have shipped even in Japan.
The first commercially available digital camera was the 1990 Dycam Model 1; it also sold as the Logitech Fotoman. It used a CCD image sensor, stored pictures digitally, and connected directly to a computer for download.[18][19][20]
In 1991, Kodak brought to market the Kodak DCS-100, the beginning of a long line of professional Kodak DCS SLR cameras that were based in part on film bodies, often Nikons. It used a 1.3 megapixel sensor and was priced at $13,000.
The move to digital formats was helped by the formation of the first JPEG and MPEG standards in 1988, which allowed image and video files to be compressed for storage. The first consumer camera with a liquid crystal display on the back was the Casio QV-10 in 1995, and the first camera to use CompactFlash was the Kodak DC-25 in 1996.
The marketplace for consumer digital cameras was originally low resolution (either analog or digital) cameras built for utility. In 1997 the first megapixel cameras for consumers were marketed. The first camera that offered the ability to record video clips may have been the Ricoh RDC-1 in 1995.
1999 saw the introduction of the Nikon D1, a 2.74 megapixel camera that was the first digital SLR developed entirely by a major manufacturer, and at a cost of under $6,000 at introduction was affordable by professional photographers and high-end consumers. This camera also used Nikon F-mount lenses, which meant film photographers could use many of the same lenses they already owned.

[edit] See also

[edit] References

  1. ^ Needham, Joseph. (1986). Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 1, Physics. Taipei: Caves Books Ltd. Page 82.
  2. ^ Jan Campbell (2005). "Film and cinema spectatorship: melodrama and mimesis". Polity. p.114. ISBN 074562930X
  3. ^ The Camera Obscura : Aristotle to Zahn
  4. ^ Renner, Eric (1999). Pinhole photography. Oxford, England: Focal Press. pp. 6–8. ISBN 0-240-80350-7. 
  5. ^ Renner (1999: 12)
  6. ^ Gernsheim, Helmut (1965). A Concise History of Photography. London: Thames and Hudson. pp. 3–6. 
  7. ^ Newhall, Beaumont (1982). The History of Photography. New York, New York: The Museum of Modern Art. p. 13. ISBN 0-87070-381-1. "Joseph Nicéphore Niépce, of Chalon-su-Saône in central France, was more successful. Niépce built on a discovery by Johann Heinrich Schultz (1724): that silver salts darken under exposure to light. Although the only example of his camera work that remains today appears to have been made in 1826, his letters leave no doubt that he had succeeded in fixing the camera's image a decade earlier." 
  8. ^ Leslie Stroebel and Richard D. Zakia (1993). The Focal encyclopedia of photography (3rd ed.). Focal Press. p. 6. ISBN 9780240514178. http://books.google.com/books?id=CU7-2ZLGFpYC&pg=PA6. 
  9. ^ Davenport, Alma (1999). The history of photography: an overview. Albuquerque, NM: University of New Mexico Press. p. 6. ISBN 0-8263-2076-7. 
  10. ^ Consumer Price Index (estimate) 1800–2008. Federal Reserve Bank of Minneapolis. Retrieved December 7, 2010.
  11. ^ US 3540011 
  12. ^ US 4057830  and US 4163256  were filed in 1972 but were only later awarded in 1976 and 1977. "1970s". http://www.digicamhistory.com/1970s.html. Retrieved 15 June 2008. 
  13. ^ "Digital Photography Milestones from Kodak". Women in Photography International. http://www.womeninphotography.org/Events-Exhibits/Kodak/EasyShare_3.html. Retrieved 17 September 2007. 
  14. ^ "Kodak blog: We Had No Idea". http://pluggedin.kodak.com/post/?id=687843. 
  15. ^ Michael R. Peres (2007). The Focal Encyclopedia of Photography (4th ed. ed.). Focal Press. ISBN 0240807405. http://books.google.com/books?id=VYyldcYfq3MC&pg=RA1-PA16&dq=sasson+ccd+fairchild&ei=sDAFR-7YA46ApwLuvYijDQ&ie=ISO-8859-1&sig=FHJgLcIA9OrCgLxeJGpanGnMs8o. 
  16. ^ Kenji Toyoda (2006). "Digital Still Cameras at a Glance". In Junichi Nakamura. Image sensors and signal processing for digital still cameras. CRC Press. p. 5. ISBN 9780849335457. http://books.google.com/books?id=UY6QzgzgieYC&pg=PA5&dq=sony+mavica+analog&lr=&as_brr=3&ei=WhxiSpvkG4nokATQg7iiDg. 
  17. ^ Askey, Phil (2001). "Silicon Film – vaporized-ware". http://www.dpreview.com/news/0109/01091702siliconfilmvaporizes.asp. Retrieved 20 February 2008. 
  18. ^ "1990". DigiCam History Dot Com. http://www.digicamhistory.com/1990.html. Retrieved 17 September 2007. 
  19. ^ "Dycam Model 1: The world's first consumer digital still camera". DigiBarn computer museum. http://www.digibarn.com/collections/cameras/dycam-model1/index.html. 
  20. ^ Carolyn Said, "DYCAM Model 1: The first portable Digital Still Camera", MacWeek, vol. 4, No. 35, 16 Oct. 1990, p. 34.

[edit] External links

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