Prime lenses have a fixed focal lengthThe optical distance in millimetres between a camera lens and the film (or sensor on a digital camera). It determines the height and width of the scene being captured, known as the field of view. More. Distinct from zoom lenses, which have variable focal lengths. Sometimes called unifocal lenses. A typical and common prime lens for 35mm film cameras is the 50mm lens – sometimes know as the nifty-fifty.
