The Anatomy of a lens

It's well worth taking a bit of time to find your way around your lenses and brushing up your knowledge of all key features. Lenses enable us to isolate a subject from its surroundings and create a sense of frame wide aspects of a scene (wide angle lens) or to isolate smaller sections within it (telephoto lens), thereby presenting the world in new ways.


Filter thread
Every lens has a thread of a given diameter at the ed of the lens barrel that lets you attach screw-in filters, such as a polariser or UV.

Distance scale
This is a scale on the lens barrel in meters (and feet) that indicates the distance between the subject and the camera as well as the depth of field at a given aperture.

AF/MF switch
This switch enables you to select either Auto Focusing mode (AF) or Manual Focusing mode (MF). Some lenses have the additional feature that allows manual focusing override while in AF mode.

Zoom ring
This ring enables you to alter the focal length of the lens by rotating the ring on the lens barrel, which causes the optical elements (individually lenses) within the lens to move accordingly.

Lens Hood
Supplied with some lenses but an optional extra for others, the lens hood's role is to prevent light striking the font of the lens, which can degrade image quality as a result of flare.

Focus ring
This enables you to manually focus the lens. Focusing is performed automatically on most lenses but a focusing ring allows you to override thus when necessary.

Aperture ring
This is usually positioned close to the lens mount, and allows you to set the aperture manually on the lens. Not present on most modern lenses apart from Nikon's.

Lens Mount
This allows the lens to be mounted to a compatible camera with fully automatic coupling . Independent brand lenses can be bought with an appropriate lens mount for your camera make.