CAMERA

Today, you can buy many different sorts of camera: digital, single-use automatic, SLR (Single Lens Reflex)... cameras have come a long way since the first  camera obscuras were invented hundreds years ago.

What is camera?
A camera at its simplest focuses light onto film to make an image. Old-fashioned 'camera obscuras' used a lens to protect the image  of a whole landscape onto a screen in a darkened room. Standard cameras focus though a lens to record an image as a single photo that you can take away.

An example of a camera obscura. the image is reflected onto the mirror upside down, the reflecated the right way around by the second mirror.

http://en.wikipedia.org/wiki/File:Camera_Obscura_box18thCentury.jpg