The Digital Camera

2007-11-14T23:16:00.000-08:00

The Digital Camera:

A digital camera is an electronic device used to capture and store photographs digitally, instead of using photographic film like conventional cameras, or recording images in an analog format to magnetic tape like many video cameras.

Modern compact digital cameras are typically multifunctional, with some devices capable of recording sound and/or video as well as photographs. In the Western market, digital cameras now outsell their 35 mm film counterparts.

Classification:

Digital cameras can be classified into several categories:

Video cameras:

Video cameras are classified as devices whose main purpose is to record moving images.

* Professional video cameras such as those used in television and movie production. These typically have multiple image sensors (one per color) to enhance resolution and color gamut. Professional video cameras usually do not have a built-in VCR or microphone. * Camcorders used by amateurs. They generally include a microphone to record sound, and feature a small liquid crystal display to watch the video during taping and playback. * Webcams are digital cameras attached to computers, used for video conferencing or other purposes. Webcams can capture full-motion video as well, and some models include microphones or zoom ability.
In addition, many Live-Preview Digital cameras have a "movie" mode, in which images are continuously acquired at a frame rate sufficient for video.

Live-preview digital cameras:

The term digital still camera (DSC) most commonly refers to the class of live-preview digital cameras, cameras that use an electronic screen as the principal means of framing and previewing before taking the photograph. All use either a charge-coupled device (CCD) or a CMOS image sensor to sense the light intensities across the focal plane.

Many modern live-preview cameras have a movie mode, and a growing number of camcorders can take still photographs. However, even a low-end live-preview camera can take better still pictures than a mid-range video camera, and mid-range live-preview cameras have much lower video quality than low-end video cameras; that is, products are not generally optimized for both still and video photography, due to their different requirements.

Among live-preview cameras, most have a rear liquid crystal display for both preview and reviewing photographs. Transfers to a computer are commonly carried out using the USB mass storage device class (so that the camera appears as a drive) or using the Picture Transfer Protocol (PTP) and its derivatives; in addition, Firewire is sometimes supported.
The live-preview cameras are typically divided into compact (and subcompact) and bridge cameras.

Compact digital cameras:

Also called digicams, this encompasses most digital cameras. They are characterized by great ease in operation and easy focusing; this design allows for limited motion picture capability. They tend to have significantly smaller zooms than bridge and DSLR cameras. They have an extended depth of field. This allows objects at a larger range of depths to be in focus, which accounts for much of their ease of use. They excel in landscape photography and casual use. They typically save pictures in only the JPEG file format. All but the cheapest models have a built-in flash, although its guide number tends to be very low, perhaps just 6 or 8.

Bridge cameras:

Bridge or SLR-like cameras form a general group of higher-end live-preview cameras that physically resemble DSLRs and share with these some advanced features, but share with compacts the live-preview design and small sensor sizes.

Fujifilm FinePix S9000

Bridge cameras tend to have superzoom lenses, which compromises – in varying degrees, depending on the quality of the zoom lens – a "do it all" ability with barrel distortion and pincushioning. These cameras are sometimes marketed as and confused with digital SLR cameras since the bodies resemble each other. The distinguishing characteristics are that bridge cameras lack the mirror and reflex system of DSLRs, have so far been always produced with only one single sealed (non-interchangeable) lens (but accessory wide angle or telephoto converters can be attached to the front of the sealed lens), can usually take movies, record audio and the scene composition is done with either the liquid crystal display or the electronic viewfinder (EVF). The overall performance tends to be slower than a true digital SLR, but they are capable of very good image quality while being more compact and lighter than DSLRs. The high-end models of this type have comparable resolutions to low and mid-range DSLRs. Many of the these cameras can save in JPEG or RAW format. The majority have a built-in flash, often a unit which flips up over the lens. The guide number tends to be between 11 and 15.

Digital single lens reflex cameras:

Digital single-lens reflex cameras (DSLRs) are digital cameras based on film single-lens reflex cameras (SLRs), both types are characterized by the existence of a mirror and reflex system. See the main article on DSLRs for a detailed treatment of this category.

Digital rangefinders:

A rangefinder is a focusing mechanism once widely used on film cameras, but much less common in digital cameras. The term rangefinder alone is often used to mean a rangefinder camera, that is, a camera equipped with a rangefinder.

For information on digital rangefinders specifically, check the digital rangefinder section in the main article linked above.

Professional modular digital camera systems:

This category includes very high end professional equipment that can be assembled from modular components (winders, grips, lenses, etc.) to suit particular purposes. Common makes include Hasselblad and Mamiya. They were developed for medium or large format film sizes, as these captured greater detail and could be enlarged more than 35mm.

Typically these cameras are used in studios for commercial production; being bulky and awkward to carry they are rarely used in action or nature photography. They can often be converted into either film or digital use by changing out the back part of the unit, hence the use of terms such as a "digital back" or "film back." These cameras are very expensive (up to $40,000) and are typically not seen in the hands of consumers.

Conversion of film cameras to digital:

When digital cameras became common, a question many photographers asked was if their film cameras could be converted to digital. The answer was yes and no. For the majority of 35 mm film cameras the answer is no, the reworking and cost would be too great, especially as lenses have been evolving as well as cameras. For the most part a conversion to digital, to give enough space for the electronics and allow a liquid crystal display to preview, would require removing the back of the camera and replacing it with a custom built digital unit.

Many early professional SLR cameras, such as the NC2000 and the Kodak DCS series, were developed from 35 mm film cameras. The technology of the time, however, meant that rather than being a digital "back" the body was mounted on a large and blocky digital unit, often bigger than the camera portion itself. These were factory built cameras, however, not aftermarket conversions.

A notable exception was a device called the EFS-1, which was developed by Silicon Film from ca. 1998–2001. It was intended to insert into a film camera in the place of film, giving the camera a 1.3 MP resolution and a capacity of 24 shots. Units were demonstrated, and in 2002 the company was developing the EFS-10, a 10 MP device that was more a true digital back.
A few 35 mm cameras have had digital backs made by their manufacturer, Leica being a notable example. Medium format and large format cameras (those using film stock greater than 35 mm), have users who are capable of and willing to pay the price a low unit production digital back requires, typically over $10,000. These cameras also tend to be highly modular, with handgrips, film backs, winders, and lenses available separately to fit various needs.

The very large sensor these backs use leads to enormous image sizes. The largest in early 2006 is the Phase One's P45 39 MP imageback, creating a single TIFF image of size up to 224.6 MB. Medium format digitals are geared more towards studio and portrait photography than their smaller DSLR counterparts, the ISO speed in particular tends to have a maximum of 400, versus 6400 for some DSLR cameras.

History:

Early development:

Steven Sasson, an Eastman Kodak engineer, with his prototype digital camera
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. Eugene F. Lally of the Jet Propulsion Laboratory published the first description of how to produce still photos in a digital domain using a mosaic photosensor. The purpose was to provide onboard navigation information to astronauts during missions to planets. The mosaic array periodically recorded still photos of star and planet locations during transit and when approaching a planet provided additional stadiametric information for orbiting and landing guidance. The concept included camera design elements foreshadowing the first digital camera.
Texas Instruments designed a filmless analog camera in 1972, but it is not known if it was ever built. The first recorded attempt at building a digital camera was by Steven Sasson, an engineer at Eastman Kodak. It used the then-new solid-state CCD image sensor chips developed by Fairchild Semiconductor in 1973. The camera weighed 8 pounds (3.6 kg), recorded black and white images to a cassette tape, had a resolution of 0.01 megapixel (10,000 pixels), and took 23 seconds to capture its first image in December of 1975. The prototype camera was a technical exercise, not intended for production.

Analog electronic cameras:

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 based on television technology that recorded to a 2 × 2 inch "video floppy". 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.

Analog cameras do not appear to have reached the market until 1986 with the Canon RC-701. Canon demonstrated this model at the 1984 Olympics, printing the images in newspapers. 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.
The first analog 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.