The two main functions of the lens of the eye are to focus light onto the retina and to help the eye focus on objects at various distances. The lens of the eye is a rubbery, jellylike structure. It is located behind the cornea and is held in place by tendons that are attached to a set of muscles called ciliary muscles.Know More
The tendons and ciliary muscles help the eye to focus by either relaxing or pulling the lens, allowing it to become either more spherical or flatter in shape. This adjustment in the shape of the lens permits the eye to focus on objects at various distances. The adjustment occurs very quickly, allowing the eye to focus on a nearby object at one moment and a far-away object at the next moment.
Sometimes the lens of the eye does not function properly or needs extra assistance to focus on objects correctly. Eyeglasses or contact lenses provide this assistance. The lens of the eye may also become cloudy with age, which is a condition known as a cataract. Lens replacement surgery is available for people with cataracts. The lens of the eye may also deteriorate with age, and its ability to adjust from a distant to a near focus declines. Many older individuals require reading glasses to correct this issue.Learn more about Technology
A parfocal lens is a zoom lens that holds its focus throughout its entire zoom range. A varifocal lens, on the other hand, is a zoom lens that requires the lens to be refocused if the focal length is changed.Full Answer >
A zoom lens is meant to take pictures at a variety of distances while telephoto lenses are meant for a single distance. Telephoto lenses are usually defined as any lens more than 50 millimeters, though others define it as any lens more than 100 millimeters.Full Answer >
A wide-angle lens is one in which the focal length is less than 35 mm creating an angle view that is greater than 55 degrees. The key concept in a wide-angle lens is that the smaller the focal length, the more effective the lens is in achieving unique effects.Full Answer >
A Carl Zeiss Vario-Tessar lens is a state-of-the-art glass formation specifically designed for highly detailed photographic visual recording. The lenses are derived from the designs of Carl Zeiss, and they are famously used by Sony.Full Answer >