The lens is the eye of the camera system. In order to get the look that you want, you first need a basic understanding of what role the lens plays in capturing the scene.
What is a lens?
A lens is made up of several pieces of glass, each called an element. Some of the elements are bound together and then mounted to the lens housing. The lens gathers the rays of light and projects them to form an image on the sensor area of the camera, whether that is the film or digital chip.
Focal Length
The focal length of a lens determines its angle of view, and also how much the subject will be magnified for a given camera position. Focal length also determines the perspective of an image.