An electronic imager is an electronic device that detects electromagnetic radiation with spatial resolution. It is the electronic analog of the photographic plate or film. Common applications are digital photography and astrophotography. Electromagnetic radiation or EM radiation is a combination (cross product) of oscillating electric and magnetic fields perpendicular to each other, moving through space as a wave, effectively transporting energy and momentum. ... Photographic plates were one of the earliest forms of photographic film, in which a light-sensitive emulsion of silver salts was applied to a glass plate. ... Photographic film a sheet of plastic (polyester, celluloid (nitrocellulose) or cellulose acetate) coated with an emulsion containing light-sensitive silver halide salts (bonded by gelatin) with variable crystal sizes that determine the sensitivity or resolution of the film. ... Lens and mounting of a large format camera Photography is the process of making pictures by means of the action of light. ... Astrophotography is a specialised type of photography that entails taking photographs of items in the night sky such as planets, stars, and deep sky objects. ...

The imager most commonly used in the optical and ultraviolet regions of the spectrum is the CCD. Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. ... The electromagnetic spectrum encompasses all possible wavelengths of electromagnetic radiation. ... A charge-coupled device (CCD) is a sensor for recording images, consisting of an integrated circuit containing an array of linked, or coupled, capacitors. ...