Camera Parts: Lens
One of the fundamental camera parts is the lens. The dictionary definition of a lens is a curved, transparent material that bends the light passing through it. A camera lens contains several of these lenses, which are generally made of glass. These are the lens elements, and are housed inside a metal or plastic cylinder. This whole, self-contained unit is referred to as the camera lens. All the lens elements inside a camera lens take in light, and bends or focuses it into a clear image on the camera's film or digital sensor.
The camera lens has a focusing ring on its body. Rotating the ring moves certain lens elements forwards and backwards, adjusting the focal point of the lens and presenting a clear image on the film or sensor. Some lenses will do this automatically--a feature called auto-focus.
Some camera lenses allow some lens elements to move farther apart, changing the focal length of the lens. This changes the apparent distance to the objects in the image, making them seem closer or farther away. The process of this is generally referred to as zooming in or zooming out.
The camera lens contains other parts, such as the aperture, distance scale and lens mount, just to name a few.