Photography

Photography is the science, art and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film.

Typically, a lens is used to focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed exposure. With an electronic image sensor, this produces an electrical charge at each pixel, which is electronically processed and stored in a digital image file for subsequent display or processing. The result with photographic emulsion is an invisible latent image, which is later chemically "developed" into a visible image, either negative or positive depending on the purpose of the photographic material and the method of processing. A negative image on film is traditionally used to photographically create a positive image on a paper base, known as a print, either by using an enlarger or by contact printing.

Science of photography

The science of photography refers to the use of science, such as chemistry and physics, in all aspects of photography. This applies to the camera, its lenses, physical operation of the camera, electronic camera internals, and the process of developing film in order to take and develop pictures properly.

Law of Reciprocity

The law of reciprocity describes how light intensity and duration trade off to make an exposure—it defines the relationship between shutter speed and aperture, for a given total exposure. Changes to any of these elements are often measured in units known as "stops"; a stop is equal to a factor of two.

Halving the amount light exposing the film can be achieved either by:

Likewise, doubling the amount of light exposing the film can be achieved by the opposite of one of these operations.

The luminance of the scene, as measured on a reflected light meter, also affects the exposure proportionately. The amount of light required for proper exposure depends on the film speed; which can be varied in stops or fractions of stops. With either of these changes, the aperture or shutter speed can be adjusted by an equal number of stops to get to a suitable exposure.

Forum

Forum (plural forums or fora) may refer to:

Buildings

Shopping centres

Sports and entertainment

Penthouse Forum

Penthouse Forum, sometimes simply Forum, is a magazine owned by FriendFinder Networks, the publishers of Penthouse magazine.

History and profile

Penthouse Forum was started in March 1970 as a supplement to Penthouse. Unlike the main Penthouse title, Penthouse Forum is more journalistic than pornographic, and features editorials and opinion pieces on controversial contemporary topics. It features regular monthly columns titled "On the Boards", "On the Beltway", and "On the Edge". It also features a section for the "Letter of the Month".

Notable contributors

Alastair Campbell, a journalist and Tony Blair's former Director of Communications, was a contributor to the magazine, as was Chad Varah, the founder of The Samaritans charity and an Anglican priest, who was a consultant on sex education for the magazine.

In July 2006 the rights to the UK edition were licensed to Trojan Publishing.

See also

References

External links

Forum (KQED)

Forum is a two-hour live call-in radio program produced by KQED-FM, presenting discussions of local, state, national and international issues, and in-depth interviews. The program began in 1990 as a politics-oriented talk show, created and hosted by Kevin Pursglove. Since 1993, it has been hosted by scholar, author, professor, and former KGO Radio host Michael Krasny, who broadened the program's scope to a cross-section of current events.

The format of Forum varies from show to show, but generally involves an in-person interview followed by public Q&A via phone or email with one or more subjects, often nationally prominent authors and scholars. The program airs for two hours on weekday mornings, with an hour repeated in the evening.

References

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