Photography is fascinating.
There are almost infinite purposes of photography. It allows to freeze time and conserve memories like a time-capsule. Many people document events, journeys or other scenes of their lives because they want evidence that they participated in an event at a particular time and place. While we may also take such photos to show other people in the present, most photos primarily serve to remember past events ourselves or to show them to others in the future. Also, a common motive for photography is to document something for later analysis. Investigation authorities take photos of crime scenes to find suspects guilty of a crime. Astrologers take advantage of photography to see astrological objects such as galaxies or supernovas. Sport events use photo-finish to find out which competitor won the race. Wildlife researchers use special cameras to document wildlife movements or to find animal trails. Although based on another technology, x-ray diagnostics can also be described as a special form of photography. Since the development of digital cameras and social media, photography has also become a way of communication. Many people use photos as a way to show people the world through their eyes. Sometimes photographs are taken to create something of an aesthetic quality or to become part of a project or as a form of creative expression.
While the history of photography dates back almost 200 years and cameras have evolved from chunky wooden boxes to tiny smartphone cameras, the basic principles have not changed at all. Every photo camera has an opening that transforms (either visible or invisible) light from the surrounding scene onto a sensitive area in the inside that reacts to the incoming light. The transformation was initially done by a tiny pinhole, however it was soon realized that better results can be achieved when glass lenses are added into the camera opening. While early cameras used photographic film to generate an image, modern cameras feature electronic sensors to react to light.
However, before going into the details of camera technology, this introduction will provide a short insight into the physics of light and image formation. An overview of the different camera systems will conclude this introduction.