In optics, a shade is a filter that absorbs light of certain wavelengths, while allowing others to pass. Shades are used to protect the eyes from excessive brightness and glare, and can enhance contrast or color perception. sunglasses are perhaps the most common type of shade.
Shades can be made from a variety of materials, including glass, plastic, metal, and fabrics. The tint of a shade is determined by its absorbing properties; darker shades absorb more light than lighter ones. Some shades also have polarizing or reflective properties.
sunglasses were first developed in the early 20th century to protect pilots’ eyes from the bright sunlight at high altitudes. Today, they are worn for a variety of reasons, including fashion, protection from UV radiation, and reducing glare when driving. Polarized sunglasses are especially effective at reducing glare from water surfaces such as lakes and oceans.
Shades are also used in photography and videography to control the amount of light reaching the film or sensor. This allows for greater creativity in image making, as well as more precise control over exposure levels. In some cases, such as with infrared photography, an appropriate filter must be used to allow only certain wavelengths of light to reach the film or sensor.
While often thought of as simply darkening devices, shades can actually enhance certain colors while filtering out others. For example, yellow-tinted glasses can make green objects appear brighter and easier to see against a background of blue sky. Orange-tinted shades may improve contrast for people with red-green color blindness (protanopia).