Digital photography uses cameras containing arrays of electronic photodetectors interfaced to an analog-to-digital converter (ADC) to produce images focused by a lens, as opposed to an exposure on photographic film. The digitized image is stored as a computer file ready for further digital processing, viewing, electronic publishing, or digital printing. It is a form of digital imaging based on gathering visible light.
The Mars Orbiter Camera selected by NASA in 1986 (costing US$44 million) contains a 32-bit radiation-hardened 10 MHz processor and 12 MB of DRAM, then considered state of the art.
Nikon D700 — a 12.1-megapixel full-frame DSLR
Canon PowerShot A95
First digital image ever created, by Russell Kirsch. It is an image of his son, Walden.
Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation. There are a wide variety of photodetectors which may be classified by mechanism of detection, such as photoelectric or photochemical effects, or by various performance metrics, such as spectral response. Semiconductor-based photodetectors typically
use a p–n junction that converts photons into charge. The absorbed photons make electron–hole pairs in the depletion region. Photodiodes and photo transistors are a few examples of photo detectors. Solar cells convert some of the light energy absorbed into electrical energy.
A photodetector salvaged from a CD-ROM drive. The photodetector contains three photodiodes, visible in the photo (in center).