Lensfocusing

Lensfocusing, also known as focal length adjustment or simply focusing, is the process of adjusting the distance between a lens and the sensor or film in a camera or other optical device to ensure that an object at a specific distance appears sharp and clear in the final image. This adjustment manipulates the point at which light rays converge after passing through the lens.

In cameras, focusing is achieved by moving the lens elements closer to or further from the image plane. This movement changes the focal length of the lens system, effectively altering where the sharpest image is formed. Different lenses have different focusing mechanisms. Some have manual focus rings that the user rotates, while others employ autofocus systems that automatically adjust the lens position.

The distance from the lens to the point where light rays converge to form a sharp image is called the focal point. The distance between the lens and the image sensor/film that produces a sharp image of a distant object is the focal plane. When an object is not at infinity, the lens needs to be adjusted so that its focal plane aligns with the image sensor or film.

Autofocus systems in modern cameras utilize various technologies, such as phase detection or contrast detection, to determine the correct focus distance and automatically adjust the lens. Manual focusing requires the user to visually assess the sharpness of the image, often using a viewfinder or live view display, and adjust the focus ring accordingly. Proper lensfocusing is crucial for achieving clear, detailed photographs and is a fundamental skill in photography and optical instrument operation.