The concept and use of the camera is very much older than digital photography as we understand it. The basic optical principles of the pinhole are commented on in Chinese texts from the fifth century BC.

More More >>

The word camera is derived from camera obscura (Latin for dark chamber) and the principal can be traced back to the ancient Greeks and Aristotle. More More >>

It was noticed that if a very small hole (a pinhole) penetrated the wall of a darkened room, an image of the scene outside was projected onto the opposite wall. The projected image was upside down and laterally reversed. This is exactly what happens with all cameras and also pour eye. The image on the right, apparently the first published illustration of a camera obscura, is of Gemma Frisius observing the solar eclipse in 1544

From the 13th Century Roger Bacon, an English monk and philosopher,  and his contemporaries used the devise to observe eclipse of the sun, which could not be done directly without damaging the eyes.

The design was significantly improved with addition of a glass lens to form a brighter and sharper image during the mid-1500s. Artists began using small portable versions of what became known as the camera obscura ( this is where the title Carbon Obscura came from) to aid them in drawing realistic representations of portraits, landscapes and architectural subjects.  A thin piece of transparent paper was laid on the glass where the image formed and the artist traced the outline of the scene they wanted onto the paper. The camera obscura was directly responsible for the fascination and understanding of geometric perspective (single point perspective) developed during the Renaissance and the rebirth of Classical culture.

Once an effective photographic process was invented around 1839 the tracing paper was replaced with a sensitized material where the image could be imprinted directly onto the paper. From here the camera and the photographic process as we know it evolved.

So the digital cameras we use can simply be seen as a light tight box, with a single small opening that lets the light onto the sensor.