Let’s start with the fact that Photography (derived from the Greek photos- for “light” and -graphos for “drawing”) is the art, science, and practice of creating durable images by recording light or other electromagnetic radiation, either chemically by means of a light-sensitive material such as photographic film, or electronically by means of an image sensor. 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.
Now that we covered the basic idea of the “making of an image”, let’s explore the three different types of photography:
Analog photography is a commonly used term for photography that uses a progressively changing recording medium, which may be either chemical process based (e.g., photographic film or plate) or electronic (e.g., vidicon or CCD sensor). Through common usage, this term has come to mean anything that is “not digital” despite some amount of controversy that the use of film isn’t a true “analog” process.
In a film camera that uses the gelatin-silver process, light falling upon photographic emulsions containing silver halides is recorded as a latent image. The latent image is subjected to photographic processing, which makes it visible and insensitive to light.
In a video camera or digital still camera, the signal is captured with a video camera tube or charge-coupled device sensor, which sends the picture to be processed by the camera’s electronics. The signal can be transmitted or recorded on a storage device for later playback.
Digital photography uses an array of electronic photodetectors to capture the image focused by the lens, as opposed to an exposure on photographic film. The captured image is then digitized and stored as a computer file ready for digital processing, viewing, digital publishing or printing. Until the advent of such technology, photographs were made by exposing light-sensitive photographic film, and used chemical photographic processing to develop and stabilize the image. By contrast, digital photographs can be displayed, printed, stored, manipulated, transmitted, and archived using digital and computer techniques, without chemical processing. Digital photography is one of several forms of digital imaging. Digital images are also created by non-photographic equipment such as computed tomography scanners and radio telescopes. Digital images can also be made by scanning other photographic images.
Instant film is a type of photographic film invented by Agfa, but first introduced by Polaroid to be used in an instant camera (and, with accessory hardware, with many professional film cameras). The film contains the chemicals needed for developing and fixing the photo, and the instant camera exposes and initiates the developing process after a photograph has been taken. In earlier Polaroid instant cameras the film is pulled through rollers which breaks open a pod containing a reagent that is spread between the exposed negative and receiving the positive sheet. This film sandwich develops for a predetermined time, depending on film type and ambient temperature, after which the positive sheet is peeled away from the negative to reveal the developed photo. In 1972, Polaroid introduced an integral film, which incorporated timing and receiving layers to automatically develop and fix the photo without any intervention from the photographer. Instant film is available in sizes from 24 mm × 36 mm (similar to 135 films) up to 50.8 cm × 61 cm size, with the most popular film sizes for consumer snapshots being approximately 83mm × 108mm (the image itself is smaller as it is surrounded by a border). The instant film was used where it was undesirable to have to wait for a roll of conventional film to be finished and processed, e.g., documenting evidence in law enforcement, in health care and scientific applications, and producing photographs for passports and other identity documents, and simply for snapshots to be seen immediately. Some photographers use instant film for test shots, to see how a subject or setup looks before using conventional film for the final exposure. Instant film is also used by artists to achieve effects that are impossible to accomplish with traditional photography, by manipulating the emulsion during the developing process or separating the image emulsion from the film base. As of 2012 three companies manufacture instant film: Fuji, Polaroid, and The Impossible Project.
After learning more about photography and how it works, next up I will spend some time on the History of Photography in my next blog post.