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Lens and mounting of a large format camera
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Photography is the process of making pictures by means of the action of light. It involves recording light patterns, as reflected from objects, onto a sensitive medium through a timed exposure. The process is done through mechanical, chemical or digital devices commonly known as cameras.

The word comes from the Greek words φως phos ("light"), and γραφις graphis ("stylus", "paintbrush") or γραφη graphê, together meaning "drawing with light" or "representation by means of lines" or "drawing."

Photographic image forming devices

Most commonly a camera or camera obscura is the image forming device and photographic film or a digital storage card is the recording medium, although other methods are available. For instance, the photocopy or xerography machine forms permanent images but uses the transfer of static electrical charges rather than photographic film, hence the term electrophotography. The rayographs published by Man Ray in 1922 are images produced by the shadows of objects cast on the photographic paper, without the use of a camera. And one can place objects directly on the glass of a scanner to produce pictures electronically.

Photographers control the camera to expose the light recording material (usually film or a charge-coupled device) to light. After processing, this produces an image whose contents are acceptably sharp, bright and composed to achieve the objective of taking the photograph.

The controls include:

  • Focus
  • Aperture of the lens
  • Duration of exposure (or shutter speed)
  • Focal length of the lens (telephoto, macro, wide angle, or zoom)
  • Sensitivity of the medium to light intensity and color/wavelength
  • Filters, scrims, or other special effects that may be placed between the subject and the light recording material, either in front of or behind the lens
  • The nature of the light recording material itself, for example, its resolution as measured in pixels or "grains" of silver halide

The controls are inter-related, as the total amount of light reaching the film plane (the "exposure") changes proportionately with the duration of exposure, aperture of the lens, and focal length of the lens (which changes as the lens is focused, or if it is "zoomed"). Changing any of these will, therefore, alter the exposure. Many lenses will automatically adjust the aperture to account for changes in focus, and some will do so for changes in zoom as well.

The duration of an exposure is referred to as the "shutter speed," often even in cameras that don't have a physical shutter, and is typically measured in fractions of a second. The aperture is expressed as a proportion to the focal length of the lens (which is not necessarily the physical distance from the film plane to the end of the lens), and therefore is often called an f-number, or an f-stop. If the diameter of the aperture (apertures are typically round) is one quarter of the focal length, then that aperture is called "f/4." The f-stops that might be found on a typical lens include 2.8, 4, 5.6, 8, 11, 16, 22, 32, where going up "one stop" doubles the amount of light reaching the film, and "stopping down" one stop halves the amount of light.

In order to achieve a given exposure, various combinations of shutter speed and aperture could be used. For example, f/8 at 1/60th of a second and f/4 at 1/120th of a second yield the same amount of light. However, the combination chosen impacts the final result. In addition to the subject or camera movement that might vary depending on the shutter speed, the aperture (and focal length of the lens) determine the "depth of field," which refers to the range of distances from the lens that will be considered in acceptable focus. For example, using a long lens and a large aperture, such as might be used with a large format camera, a subject's eyes might be in sharp focus while the tip of his nose is noticeably blurred. If the aperture is made smaller, or a shorter lens is used, then both the subject's eyes and nose can be brought into focus at the same time. If a very small aperture is used, such as a pinhole, then a very wide range of distance can be brought into focus at once.

Finally, image capture is only half of the image forming process. Regardless of the light recording material used, some sort of process or processes must be employed to render the "latent image" captured by the camera into the final photographic work. In addition to the camera controls, the processing variables have a significant impact on the final result.

Uses of photography

Photography can be classified under imaging technology and has gained the interest of scientists and artists from its inception. Scientists have used its capacity to make accurate recordings, such as Eadweard Muybridge in his study of human and animal locomotion (1887). Artists have been equally interested by this aspect but have also tried to explore other avenues than the photo-mechanical representation of reality, such as the pictorialist movement. Military, police and security forces use photography for surveillance, recognition and data storage.

History of photography

Nicéphore Niépce's earliest surviving photograph, c. 1826
File:First photo sketch.jpg
Sketch of the same scene

Invention

Main article: History of the camera

Chemical photography

Projecting images onto surfaces has been done for centuries. The camera obscura and the camera lucida were used by artists to trace scenes as early as the 16th century. These early cameras did not fix an image in time; they only projected what was before an opening in the wall of a darkened room onto a surface. In effect, the entire room was turned into a large pinhole camera. Indeed, the phrase camera obscura literally means "darkened room," and it is after these darkened rooms that all modern cameras have been named.

The first photograph is considered to be an image produced in 1826 by the French inventor Nicéphore Niépce on a polished pewter plate covered with a petroleum derivative called bitumen of Judea. It was produced with a camera, and required an eight hour exposure in bright sunshine. However, this process turned out to be a dead end and Niépce began experimenting with silver compounds based on a Johann Heinrich Schultz discovery in 1724 that a silver and chalk mixture darkens when exposed to light.

Niépce, in Chalon-sur-Saône, and the artist Jacques Daguerre, in Paris, refined the existing silver process in a partnership. In 1833 Niépce died unexpectedly of a stroke, leaving his notes to Daguerre. While he had no scientific background, Daguerre made two pivotal contributions to the process. He discovered that by exposing the silver firstly to iodine vapour, before exposure to light, and then to mercury fumes after the photograph was taken, a latent image could be formed and made visible. By then bathing the plate in a salt bath the image could be fixed. In 1839 Daguerre announced that he had invented a process using silver on a copper plate called the Daguerreotype. A similar process is still used today for Polaroids®. The French government bought the patent and immediately made it public domain.

Across the English Channel, William Fox Talbot had earlier discovered another means to fix a silver process image but had kept it secret. After reading about Daguerre's invention, Talbot refined his process, so that it might be fast enough to take photographs of people as Daguerre had done, and by 1840 he had invented the calotype process. He coated paper sheets with silver chloride to create an intermediate negative image. Unlike a daguerreotype, a calotype negative could be used to reproduce positive prints, like most chemical films do today. Talbot patented this process, which greatly limited its adoption. He spent the rest of his life in lawsuits defending the patent until he gave up on photography altogether. But later this process was refined by George Eastman and is today the basic technology used by chemical film cameras. Hippolyte Bayard also developed a method of photography, but delayed announcing it and so was not recognized as its inventor.

File:Photo NB JPG.jpg
In the darkroom

In 1851 Frederick Scott Archer invented the wet collodion process. It was the process used by Lewis Carrol.

Reference

  • Coe, Brian. The Birth of Photography. Ash & Grant, 1976.

Social history

Popularization

The Daguerreotype proved popular as it responded to the demand for portraiture emerging from the middle classes during the Industrial Revolution. This demand, that could not be met in volume and in cost by oil painting, may well have been the push for the development of photography. But still daguerreotypes, while beautiful, were fragile and difficult to copy. A single photograph taken in a portrait studio could cost $1000 in 2005 dollars. Photographers also encouraged chemists to refine the process of making many copies cheaply, which eventually lead them back to Talbot's process. Ultimately, the modern photographic process came about from a series of refinements and improvements in the first 20 years. In 1884 George Eastman, of Rochester, New York, developed dry gel on paper, or film, to replace the photographic plate, so that a photographer no longer needed to carry boxes of plates and toxic chemicals around. In July of 1888 Eastman's Kodak camera went on the market with the slogan "You press the button, we do the rest". Now anyone could take a photograph and leave the dangerous portions of the process to others. Photography became available for the mass-market in 1901 with the introduction of Kodak Brownie. Very little has changed in chemical photography since then, though color film has become the standard, as well as automatic focus and automatic exposure. Digital recording of images is becoming increasingly prevalent, as digital cameras allow instant previews on LCD screens among other benefits, and the resolution of top of the range models has exceeded high quality 35mm film while lower resolution models have become affordable. For the enthusiast photographer processing black and white film, little has changed since the introduction of the 35mm film Leica camera in 1925.

Economic history

In the nineteenth century, photography developed rapidly as a commercial service. In the U.S. in 1890, the number of professional photographers was about the same as the number of accountants, artists, and dentists, respectively, and about ten times greater than the number of authors. End-user supplies of photographic equipment accounted for only about 20% of industry revenue.

Several trends characterize the photographic industry from the end of the nineteenth century to the end of the twentieth century. The ratio of revenue from end-user photographic supplies to revenue from professional services rose by an order of magnitude. The prevalence of personal cameras and the ratio of end-user photographs rose closely in tandem with the prevalence of telephone and the telephone conversation minutes. However, the ratio of photographic industry revenue to telephone industry revenue dropped sharply.[1]

Given the development of new digital technologies for creating and sharing images, and of new communications devices, e.g. camera phones, understanding the economics of image use are becoming increasingly important for understanding the evolution of the communications industry as a whole.

Resources

Jenkins, Reese V. Images & Enterprise: Technology and the American Photographic Industry 1839-1925. Baltimore, The Johns Hopkins University Press, 1975. The book provides a fine overview of the economics of photography and is especially strong on the growth and development of the Eastman Kodak Company.

Color photography

Main article: color photography

Color photography was explored throughout the 1800s. Initial experiments in color could not fix the photograph and prevent the color from fading. The first permanent color photo was taken in 1861 by the physicist James Clerk Maxwell.

One of the early methods of taking color photos was to use three cameras. Each camera would have a color filter in front of the lens. This technique provides the photographer with the three basic channels required to recreate a color image in a darkroom or processing plant. Russian photographer Sergei Mikhailovich Prokudin-Gorskii developed another technique, with three color plates taken in quick succession.

Practical application of the technique was held back by the very limited colour response of early film; however, in the early 1900s, following the work of photo-chemists such as H. W. Vogel, emulsions with adequate sensitivity to green and red light at last became available.

The first color film, Autochrome, thus did not reach the market until 1907; it was based on a 'screen-plate' filter made of dyed dots of potato starch. The first modern ('integrated tri-pack') color film, Kodachrome, was introduced in 1935 based on three colored emulsions. Most modern color films, except Kodachrome, are based on technology developed for Agfacolor (as 'Agfacolor Neue') in 1936. Instant color film was introduced by Polaroid in 1963.

Color photography may form images as a positive transparency, intended for use in a slide projector or as color negatives, intended for use in creating positive color enlargements on specially coated paper. The latter is now the most common form of film (non-digital) color photography, owing to the introduction of automated photoprinting equipment.

Digital photography

Main article: digital photography

Having fun with photography: manipulation of the scanned print in a graphics program puts these two brave people on top of an Austrian cable car. Click on the picture to see the three components.

Traditional photography was a considerable burden for photographers working at remote locations (such as press correspondents) without access to processing facilities. With increased competition from television, there was pressure to deliver their images to newspapers with greater speed. Photo-journalists at remote locations would carry a miniature photo lab with them, and some means of transmitting their images down the telephone line. In 1981, Sony unveiled the first consumer camera to use a CCD for imaging, and which required no film -- the Sony Mavica. While the Mavica did save images to disk, the images themselves were displayed on television, and therefore the camera could not be considered fully digital. In 1990, Kodak unveiled the DCS 100, the first commercially available digital camera. Its cost precluded any use other than photojournalism and professional applications, but commercial digital photography was born.

Digital photography uses an electronic sensor such as a charge-coupled device to record the image as a piece of electronic data rather than as chemical changes on film. Some other devices, such as cell phones, now include digital photography features.

In 10 years, digital cameras have become widespread consumer products. Digital cameras now outsell film cameras, and many include features not found in film cameras such as the ability to shoot video and record audio.

Kodak announced in January 2004 that it would no longer produce reloadable 35-millimeter cameras after the end of that year. This was interpreted as a sign of the end of film photography. However, Kodak was at that time a minor actor on the reloadable film cameras market. The price of 35mm and APS compact cameras have dropped, probably due to direct competition from digital and the resulting growth of the offer of second-hand film cameras.

Digital versus Film

Film photography is anticipated to endure for some time, as dedicated amateurs and skilled artists often prefer the use of traditional and familiar materials and techniques. The comparison of resolution between film and digital photography is complex. While the resolution of commercial 35 mm color film is estimated as 19 megapixel, such a single measure of film alone is misleading. When considered in the context of film and lens in a camera, typical film achieves a resolution of about 40 line pairs per mm, or 80 dots per mm. The is equivalent to about 5.5 megapixels in the image of 35 mm film. In contrast to that, advertised pixel counts on digital cameras do not account for the actual number of pixels that are actually used to for the image, nor the effect of the Bayer pattern of sensors filters on the digital sensor, nor the image processing algorhthm to interpolate sensor pixels to image pixels, nor pixel shape, nor dynamic range. In addition, digital sensors are generally arranged in a rectangular pattern, making images susceptible to moire pattern artifacts, wheras film is immune to such effects with its random orientation of grains.

Comparisons between digital and film cameras are difficult because resolution expressed as line pairs per mm (lp/mm) are generally not published for digital cameras, or for film cameras either. Additional issues such as the flexibility and complexity of different film types is a different problem from the low light noise problems and latency from shutter release to image capture on digital cameras. Digital cameras allow most people now to do image manipulation that only the few people with access to a darkroom could do in the past with film.

The resolution of modern black and white slow speed film, exposed through a high quality prime lens working at its optimum aperture yields usable detail at a scannned file size of greater than 30 megapixels, with consumer 35mm colour negative film an effective resolution of over 12 megapixels is acheivable and in an inexpensive 35mm point and shoot camera a resolution of over 8 megapixels may be acheived. Film also offers ease of processing with drop off services for processing available in many locations, in contrast to digital photography where the process of printing can require the time and effort of the user in areas where commercial digital to print services are not yet readily available. A market of online printing of digital images has developed in response to this demand.

Commercial photography

The commercial photographic world is traditionally broken down to:

  • Advertising photography: photographs made to illustrate a service or product. These images are generally done with an advertising agency, design firm or with an in-house corporate design team.
  • Editorial photography: photographs made to illustrate a story or idea within the context of a magazine. These are usually assigned by the magazine.
  • Photojournalism: this can be considered a subset of editorial photography. Photographs made in this context are accepted as a truthful documentation of a news story.
  • Portrait and wedding photography: photographs made and sold directly to the end user of the images.
  • Fine art photography: photographs made to fulfill a vision, and reproduced to be sold directly to the end user.

The market for photographic services demonstrates the aphorism "one picture is worth a thousand words," which has an interesting basis in the history of photography. Magazines and newspapers, companies putting up Web sites, advertising agencies and other groups pay for photography.

Many people take photographs for self-fulfillment or for commercial purposes. Organizations with a budget and a need for photography have several options: they can assign a member of the organization, hire someone, run a public competition, or obtain rights to stock photographs.

Terminology

Traditionally, the product of photography has been called a photograph. The term photo is a convenient abbreviation. Many people also call them pictures.

In digital photography, the term image has begun to replace photograph. This term is neither more nor less correct than photograph, either in film or digital photography. (The term image is traditional in geometric optics.)

Although not viewed by all photographers as true photography, digital photography in fact meets all requirements to be called such. Even though there are no chemical processes, a digital camera captures a frame of whatever it happens to be pointed at, which can be viewed later.

Photography as an art form

Manual shutter control and exposure settings can achieve unusual results

During the twentieth century, both fine art photography and documentary photography became accepted by the English-speaking art world and the gallery system. In the United States, a small handful of curators spent their lives advocating to put photography in such asystem, with Alfred Stieglitz, Edward Steichen and John Szarkowski, and Hugh Edwards the most prominent among them.

Yet the aesthetics of photography is a matter that continues to be discussed regularly, especially in artistic circles. Many artists argued that photography was the mechanical reproduction of an image. If photography is authentically art, then photography in the context of art would need redefinition, such as determining what component of a photograph makes it beautiful to the viewer.

The controversy began with the earliest images "written with light": Nicéphore Niépce, Louis Daguerre, and others among the very earliest photographers were met with acclaimed, but some questioned if it met the definitions and purposes of art.

Clive Bell in his classic essay "Art" states that only one thing can distinguish art from what is not art: "significant form." Bell wrote: "There must be some one quality without which a work of art cannot exist; possessing which, in the least degree, no work is altogether worthless. What is this quality? What quality is shared by all objects that provoke our aesthetic emotions? What quality is common to Sta. Sophia and the windows at Chartres, Mexican sculpture, a Persian bowl, Chinese carpets, Giotto's frescoes at Padua, and the masterpieces of Poussin, Piero della Francesca, and Cezanne? Only one answer seems possible - significant form. In each, lines and colors combined in a particular way, certain forms and relations of forms, stir our aesthetic emotions." [2].

Aesthetic realism and photography

By Mike Schomburg, an example of opposite in oneness

Others have since examined if this criterion be applied to photography. This question has been examined by the aesthetic realism understanding of beauty.

An often neglected form of art in photography is that of portrait photography. A portrait is the basic rendering of someone’s likeness. What is perceived as a good portrait photographer not only wants to capture the true likeness, but also the personality of the individual. The photographer needs to be proficient not only in the workings and setting of the camera, but also needs to understand form and lighting. Great lighting and positioning can make someone appear at their best form if used correctly. Lighting and camera placement can also aid in correcting defects such as shortening a nose, making someone appear slimmer, and other visual enhancements. In this form of art, portrait photography takes on many roles, and can help create various moods that the individual is seeking.

Reference

Tom Ang, Dictionary of Photography and Digital Imaging, The Essential Reference for the Modern Photographer (Argentum 2001)

Additional reading

  • Freeman Patterson, Photography and The Art of Seeing, 1989, Key Porter Books, ISBN 1550130994.
  • The Oxford Companion to the Photograph, ed. by Robin Lenman, Oxford University Press 2005

See also

Basic topics in photography

Photographers

Photographs

Historical


Techniques

Photographic products

Other

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