The prime lens refers to a lens with only one fixed focal length. There is no such thing as a focal length, or in other words, there is only one field of view. The prime lens has no zoom function.

The design of a prime lens is much simpler than that of a zoom lens. However, a zoom lens usually has an impact on the image quality during the zooming process. The greatest advantage of a prime lens over a zoom machine is its fast focusing speed and stable image quality. Many digital cameras with prime lenses capture moving object images that are clear and stable, with very accurate focusing, fine pictures, very slight graininess, and relatively accurate metering.