…a piece of glass or other transparent material with curved sides for concentrating or dispersing light rays, used singly (as in a magnifying glass) or with other lenses (as in a telescope)…
…a tube or ring attached to the front of a camera lens to prevent unwanted light from reaching the film…
…a lens with a long focal length, especially as a camera attachment for taking photographs from a great distance…
…(of a camera) having two identical sets of lenses, either for taking stereoscopic pictures, or with one forming an image for viewing and the other an image to be photographed (twin-lens reflex)…
…a lens allowing a camera to change smoothly from a long shot to a close-up or vice versa by varying the focal length…
…a lens made of crown glass and usually forming one component of an achromatic lens…
…in a multiple lens optical system, the lens farthest from the eye…
…a lens suitable for taking photographs unusually close to the subject…
…a thin plastic lens placed directly on the surface of the eye to correct visual defects…
…a device for focusing a stream of electrons by means of electric or magnetic fields…
…a camera lens with a focal length approximately equal to the diagonal of the negative (taken as 50 mm for a 35 mm camera), giving a field of view similar to that of the naked eye…
…a lens that transmits light without separating it into constituent colors…
…the transparent elastic structure behind the iris by which light is focused on to the retina of the eye…
…a region of space containing a massive object whose gravitational field distorts electromagnetic radiation passing through it in a similar way to a lens, sometimes producing a multiple image of a remote object…
…an eyeglass lens having a smooth transition between parts with different focal lengths, correcting for vision at all distances…
…denoting a reflex camera in which the lens that forms the image on the film also provides the image in the viewfinder…
…a very wide-angle lens with a field of vision covering up to 180°, the scale being reduced towards the edges…
…a flat lens made of a number of concentric rings, to reduce spherical aberration…
…the lens in a telescope or microscope nearest to the object observed…
…a lens with a longer focal length than standard, giving a narrow field of view and a magnified image…
…an eyeglass lens having a smooth transition between parts with different focal lengths, correcting for vision at all distances…
…the plant which yields lentils, native to the Mediterranean and Africa and grown also for fodder…
…(of a camera) having two identical sets of lenses, either for taking stereoscopic pictures, or with one forming an image for viewing and the other an image to be photographed (twin-lens reflex)…
