Camera

An optical remote sensor. In its simplest form, it consists of the camera body, a lens and a focal plane with sensitive material.

An example of a remote sensor is a conventional camera. Light reflected from an object passes through the lens and the light-sensitive film detects it. At the moment of exposure a latent image is recorded. Developing and fixing the film in the photo laboratory generates a definite record: the photograph. This image is then subject to interpretation. Today, most remote sensors are electronic devices (digital cameras).

In a conventional camera loaded with panchromatic film (black &white film), the silver halide crystals of the light-sensitive emulsion detect radiation. The silver halide grains turn to silver metal when exposed to light, the more so the higher the intensity of the incident light. Each light ray from an object/scene triggers a chemical reaction of some particular photographic detector grain. This way, variations in radiance within a scene are detected and an image of the scene is created at the time of exposure. The record obtained is only a latent image; the film has to be developed to turn it into a photograph.