lensring

Lensring is not a formal term in optical engineering. In common usage, it is an informal label for any circular ring on a camera lens that is used to adjust a parameter or to attach accessories. The most familiar rings on a lens are the focus ring, the zoom ring, and, on older manual lenses, the aperture ring.

The focus ring is usually located toward the front of the barrel and is gripped to rotate the inner elements for focusing. The zoom ring appears on zoom lenses and changes the focal length by rotating to adjust magnification. The aperture ring, when present, controls the size of the lens aperture by rotating to preset or manual values. Some modern lenses replace or supplement these manual rings with electronic controls, including a programmable control ring that can be mapped to functions such as exposure settings through camera menus.

In addition, many lenses include a front filter ring for attaching screw-in filters. The mechanism that secures the lens to the camera body is the lens mount, which is a separate component and is not typically described as a lensring.

Materials for rings commonly include aluminum or magnesium alloys and durable plastics, often with knurled textures to improve grip. Maintenance tips emphasize keeping the rings clean, avoiding oil from fingers, and ensuring smooth, unobstructed rotation. If a ring becomes stiff or loose, it is best to have the lens serviced rather than forcing movement.

See also: camera lens, focus, aperture, zoom, lens mount, filter thread.