(optics) a positive-powered lens or group of lenses that comes after the objective lens and before the image plane or the eyepiece, serving to change the size of the image

(microscopy) A condensing lens in which the light is confined to an annular pencil by means of a small, round diaphragm (the "spot"), and used in darkfield illumination.

A highly specialized type of shaped charge, used mainly in nuclear weapons, composed of several explosive charges arranged so as to control the shape of the detonation wave passing through them.

Circle contact lens.

A telephoto lens.

(photography, informal) A telephoto lens.

(photography) A lens which produces an image similar in detail and angular perspective to the view produced by the human eye, as distinct from a wide-angle lens or a telephoto lens.

(photography) A lens having a long focal length which produces a magnified view of distant objects.

(photography) The detachable cap that protects the camera lens when the camera is not in use.

(photography) A wide-angle lens having an extremely wide field of view (approaching or exceeding 180 degrees) and producing images that are circular or distorted by curvature at the edges.