Lenses

Lenses are used to focus on the object whose image is to be captured. The lens shape (spherical or aspherical), focal length (distance between secondary principal point of the lens and the camera sensor face - may be fixed focus, varifocal or zoom) and iris operation (automatic or electrically controlled by DC power) are critical specifications, all affecting the picture quality and properties. When selecting a lens it must be known what camera sensor size is being used as this aids selection of the lens format (size attributed to the lens for compatibility), lens mount is required and the angle of view required. Lenses can be specified separately from camera purchase to improve performance.