Lens 101

You cannot talk of cameras without mentioning lenses. A good lens is the central pillar of good photography. All the good and expensive features of a camera can be rendered irrelevant by a poor quality lens. Truth be told, a camera lens is the gateway to the heart of photography.

A camera lens is a piece of technology spectacle. On one side there is the rather the simple arrangement of pieces of glass whose seemingly simple role is just to allow light pass through them into your camera. However behind this simple description is a complex optical technology that enables transition of light to produce the wonders photography is today.

Components of a Lens

  • Lens Barrel: The is the body of the lens, the tube- shaped housing made of either plastic, metal or a combination of the two and holds the lenses in their place (remember a camera lens is actually several lenses combined into one unit).
  • Optical Lens: If you look in front of a camera lens, you will see a glass lens that focuses light into the camera body and onto the film/sensor. Inside the lens body, there are several other optical lenses (called elements) that further refine the image. These lenses are sometimes called elements. Being the optical framework of a camera, their arrangement determines the focal range of the lens that has a direct correlation with the image quality of the lens.
  • Lens Mount:  All lenses attach to the camera using some sort of locking lens mount. It can be  bayonet, screw thread, and friction-lock assortments. The sole role of locking system is to attach the lens to the camera body and join any electrical connections. Camera manufacturers have proprietary design for their lens and although they may look very similar, they are not interchangeable. However there are third-party lens manufacturers who make lens that fit across several brands.
  • Focus Ring: Most lens, if not all, have a focusing ring which allows the photographer to adjust the focus of lens i.e. the focus ring is rotated to allow the photographer to focus the image. On automatic cameras, focus ring is moved automatically whenever the shutter release button (see below) halfway down is pressed. The focus ring is usually located to the immediate front or rear of the zoom ring on lens barrel. These rings are usually marked with guide numbers showing how far away a subject is when focused.
  • Zoom Ring: Sometimes referred to as focal length ring, a zoom ring is what you turn to either zoom in or out on your lens. Lenses are often described by their focal length. For example, a lens may be listed as a 16-35mm lens. This indicates that the lens can zoom from 16mm to 35mm.
  • Aperture Ring: The aperture ring allows the photographer to control the aperture (opening) on the lens, depending on the f-stop setting selected (the size of the aperture is measure by the f-stop setting). Using the aperture ring, the photographer is able to adjust the aperture blades, located inside the lens, thereby controlling the size of the opening through which light enters the camera. For automatic cameras, this adjustment is achieved through selecting electronically some camera settings.