|In 1991 the first digital cameras reached the US market: The Dycam Model 1 and the digital back Kodak DCS 100 combined with a Nikon F3.|
image by maoby (Image rights)
A Digital camera has an electronic image sensor instead of film in its image plane. The lens projects the picture onto that optoelectronic chip. The signals for brightness and colour of each singular smallest light-sensitive unit of the chip (pixel) are transfered into a digital memory device. Each original digital picture is such a file full with pixelwise informations. Usually a little one-chip-computer (camera processor) controls a digital camera. Immediately after each image shot this computer develops that data for giving a decent image while it changes the raw file's format into a compressed file format, for example the JPEG-Format. Advanced cameras offer an option to let the camera store the raw data uncompressed, for later image development on a desktop computer. A serial interface for connection to a computer makes the image-files available for archiving and/or reworking them with imaging software. Nowadays the image file transfer to the PC is achieved otherwise, by putting the camera's image data storage card into the computers memory card adaption slot, or thru W-LAN or Bluetooth interfaces, some cameras even thru built-in smartphone connected to a distant cloud space. Three kinds of sensors got to market: CCD, CMOS (front- or backlit), and the Foveon 3-layer sensors.
The process of shooting is similar to traditional photography: For each exposure, time and lens aperture are automatically chosen analog to the sensor's basic light sensitivity in relation to actual measured light intensitiy. Advanced digital cameras give the choice to do the exposure settings manually. Usually a higher light sensitivity setting can be simulated in the cameras, i.e. higher ISO light sensitivity values than base sensitivity can be set, automatically or manually. So-called noise effects appear in images with simulated higher ISO value. Anti-noise algorithms belong to the image development software. The camera-processor's software inside the camera is called firmware, stored in EEPROM-like storage type.
Many think that digital cameras have only optical elements like the lenses in common with traditional film cameras. But often there's more than the lens with its aperture diaphragm in common with analog cameras, for example the complicated optical viewfinder system of a digital single lens reflex camera (DSLR). Electro-mechanical shutters are not just found in DSLRs but also in many other digital cameras, but actually - in 2019 - there is a strong trend to improve electronically simulated shutters, so that in near future mechanical shutters will become a rarity in digital cameras. Separate sensors for focus and light intensity are more and more replaced by giving cameras focus finding and light measuring capabilities by means of their image sensors, except old-style DLSRs. Advanced cameras have their image sensor embedded in an anti shake mechanism, controlled by the camera processor during each exposure, to improve their low-light capabilities as hand cameras.
The term Analog Camera should refer to non-digital electronic cameras, which also have no film, such as the Olympus VC-100 still camera and most older video/TV cameras - not, as is almost always mistakenly intended, to film cameras.