Camera lens

A camera lens is an optical assembly that focuses light to form an image on a camera’s recording surface. Its elements and aperture control image formation, brightness, and perspective.

Refraction: The change in direction of light as it passes between materials with different refractive indices. Curved lens surfaces use refraction to redirect light rays toward an image.
Lens element: A single optical component, usually glass or plastic, that refracts light within a lens assembly. Multiple elements are arranged to focus light while correcting optical errors.
Prime lens: A camera lens with one fixed focal length rather than a variable zoom range. Its fixed view contrasts with zoom lenses and can enable simpler optical designs.
Pinhole camera: A camera that forms an image through a tiny aperture without a lens. It forms images without the refractive focusing that defines a camera lens.
Focal length: The distance from a lens’s principal plane to its focal point when focused at infinity. It sets the lens’s angle of view and strongly shapes image scale.
Lens group: One or more lens elements mounted together and moved as a unit in an optical system. Groups shift relative to one another to focus, zoom, or stabilize an image.
Zoom lens: A camera lens whose focal length can be changed across a continuous or stepped range. Moving internal groups changes framing without changing the lens-camera position.
Camera obscura: An optical device that projects an external scene through an aperture onto an interior surface. It is a broader image-projection principle from which lens-based cameras developed.
Aperture: An adjustable opening that controls how much light passes through an optical system. The lens aperture regulates exposure and affects depth of field.
Diaphragm (optics): A mechanism of overlapping blades that forms an adjustable aperture in an optical system. Its blades set the lens opening and often create the shape of out-of-focus highlights.

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