Digital single-lens reflex camera

A digital single-lens reflex camera (digital SLR or DSLR) is a digital camera that combines the optics and mechanisms of a single-lens reflex camera with a solid-state image sensor and digitally records the images from the sensor.

The reflex design scheme is the primary difference between a DSLR and other digital cameras. In the reflex design, light travels through the lens and then to a mirror that alternates to send the image to either a prism, which shows the image in the optical viewfinder, or the image sensor when the shutter release button is pressed. The viewfinder of a DSLR presents an image that will not differ substantially from what is captured by the camera's sensor, as it presents it as a direct optical view through the main camera lens rather than showing an image through a separate secondary lens.

DSLRs largely replaced film-based SLRs during the 2000s. Major camera manufacturers began to transition their product lines away from DSLR cameras to mirrorless interchangeable-lens cameras (MILCs) beginning in the 2010s.

In 1969, Willard S. Boyle and George E. Smith invented charge-coupled semiconductor devices, which can be used as analog storage registers and image sensors. A CCD (Charge-Coupled Device) imager provides a low-noise analog image signal, which is digitized when used in a digital camera. For their contribution to digital photography, Boyle and Smith were awarded the Nobel Prize for Physics in 2009.

In 1973, Fairchild developed a 100 x 100 pixel interline CCD image sensor. This CCD was used in the first commercial CCD camera, the Fairchild MV-100, which was introduced in late 1973. In 1974, Kodak scientists Peter Dillon and Albert Brault used this Fairchild CCD 202 image sensor to create the first color CCD image sensor by fabricating a red, green, and blue color filter array that was registered and bonded to the CCD. In 1975, Kodak engineer Steven Sasson built the first portable, battery-operated digital still camera, which used a zoom lens from a Kodak Super 8mm movie camera and a monochrome Fairchild 100×100 pixel CCD.

The first prototype filmless SLR camera was publicly demonstrated by Sony in August 1981. The Sony Mavica (a magnetic still video camera) used a color-striped 2/3” format CCD sensor with 280K pixels, along with analog video signal processing and recording. The Mavica electronic still camera employed a TTL single-lens reflex viewfinder, as shown in the graphic from a June 1982 Sony press release. It recorded FM-modulated analog video signals on a newly developed 2” magnetic floppy disk, dubbed the "Mavipak".

The disk format was later standardized as the "Still Video Floppy", or "SVF", so the Sony Mavica was the first "SVF-SLR" to be demonstrated, but it was not a D-SLR since it recorded analog video images rather than digital images. Starting in 1983, many Japanese companies demonstrated prototype SVF cameras, including Toshiba, Canon, Copal, Hitachi, Panasonic, Sanyo, and Mitsubishi.

The Canon RC-701, introduced in May 1986, was the first SVF camera (and the first SVF-SLR camera) sold in the US. It employed an SLR viewfinder and included a 2/3” format color CCD sensor with 380K pixels. It was sold along with removable 11-66mm and 50-150mm zoom lens.