cameralens

A camera lens is an optical assembly that gathers light and focuses it to form an image on a camera’s sensor or film. Lenses are designed to work with specific camera mounts and sensor sizes, and may be interchangeable or fixed with the body. They determine how much of the scene is captured and how large subjects appear.

Focal length, measured in millimeters, defines the lens’s field of view and magnification. Shorter focal lengths produce wider angles and more depth of field, while longer focal lengths provide a narrower angle of view and greater magnification. The maximum aperture, indicated by an f-number such as f/2.8, indicates both the amount of light the lens can gather and the degree of background blur. The image circle must cover the sensor size, and on smaller sensors the effective focal length is influenced by the crop factor.

Common categories include prime lenses, which have a fixed focal length, and zoom lenses, which cover a range of focal lengths. Within zooms, lenses are often characterized as wide-angle, standard, or telephoto. Specialized types include macro lenses for close-up work, fisheye lenses for ultra-wide, and tilt-shift lenses used in architectural photography to control perspective.

Optical design features encompass multiple glass elements and groups, with specialized elements such as low-dispersion and aspherical Glass to reduce aberrations. Coatings minimize lens flare and ghosting. Many lenses include autofocus motors for fast focusing, and some offer optical image stabilization to compensate for camera shake.

Mounts and compatibility depend on the camera system; crop factors affect the effective focal length on smaller sensors. Build quality, weight, and weather sealing vary by model and price, influencing suitability for different photography needs.