Advanced Photo System
From Freepedia
Advanced Photo System (APS) is a film format for still photography.The film is 24 mm wide, and has three image formats:
- H for "HDTV" (30.2 x 16.7 mm; aspect ratio 16:9; 4x7" print)
- C for "classic" (25.1 x 16.7 mm; aspect ratio 3:2; 4x6" print)
- P for "panoramic" (30.2 x 9.5 mm; aspect ratio 3:1; 4x12" print)
The "C" and "P" formats are formed by cropping. The full image is recorded on the film, and an image recorded in one aspect ratio can be reprinted in another. The "C" format has an equivalent aspect ratio to a 135 film image. Most APS cameras (with the exception of some disposable cameras) can record all three formats; the format selection is indicated on the film by a series of exposed squares alongside the image area or recorded on the magnetic coating (see below) depending on the camera. In the absence of an operator-specified format, the machine printing an APS roll will use these indicators to determine the output format of each print.
The film is on a polyethylene naphthalate (PEN) base, and is housed in a single-spool 39 mm long plastic cartridge. The basic diameter is 21 mm, while it measures 30mm at the slot where the film exits. The slot is protected by a lightlock door. It comes in lengths for 40, 25 and 15 exposures. The film surface is coated by a transparent magnetic coating, and the camera uses this information exchange (IX) system for recording information about each exposure. The camera handles winding and rewinding automatically, to the extent that partially exposed films can be removed and used later. Numbered symbols (called 'visual indicators') on the cartridge end indicate the status:
- Full circle: Unexposed
- Half circle: Partly exposed
- Plus sign: Fully exposed but not processed
- Square: Processed
Additionally, a tab on this end of the cartridge serves as an indicator that the cartridge has been processed; APS processing equipment will punch out this tab.
Processed (developed) film is stored in the original cartridge. For identification, every roll of APS film has a six-digit ID code on the label, which is also stored magnetically and is visible on either end of the processed negative. This ID is usually printed on the back of every individual print. This ID was designed to be an additional convenience both for the photoprocessor (who can easily match each strip of processed film with its cartridge, and each cartridge to a particular customer's order) and for the consumer, who can easily locate the correct cartridge if reprints are desired.
To facilitate automatic processing of film, a unique DX number is assigned to the different types of film.
The format was introduced in 1996 by Kodak, Agfa, Fujifilm, Nikon, Canon and others. The APS film surface area is 56% of 135 film. APS is mainly used for point and shoot amateur cameras, although some SLR systems were also created: Canon EOS IX, Minolta Vectis, Nikon Pronea with Nikon IX lenses. Of these the Canon EOS IX could use the existing 35mm SLR lenses, whereas Minolta and Nikon opted to create a new lens line-up. Using existing lenses meant that the field of view was reduced by around 1.6x, but had the advantage of a larger lens selection. Creating a new lens system on the other hand gave the possibility of creating smaller and lighter lenses as that had a smaller image circle to cover. APS SLR cameras were too expensive for the high end amateur market when they first appeared, and professional photographers stuck with 35mm cameras. Few APS film cameras are available new today.
Presently the terms APS-C and APS-H are most often used in reference to various makes of digital SLR that contain imaging sensors that are (very) roughly equivalent to their respective film dimensions given above. Concurrently to their APS SLR film cameras, some manufacturers released lenses intended for use on APS film cameras, in that they had a similar field of view to a given longer focal length lens on a 35mm camera. Some of these lenses have survived and are now marketed towards use on "APS" digital SLRs for the same reason.
