What is a prime lens?

A prime lens is characterized by having a fixed focal length, meaning it cannot zoom in or out like a zoom lens, which has variable focal lengths. This fixed nature allows prime lenses to typically offer better optical quality, faster maximum apertures for low-light capabilities, and more consistent handling of distortion and aberrations compared to zoom lenses. Photographers often use prime lenses for their ability to produce sharp images with a shallow depth of field, making them particularly popular for portrait and landscape photography.

While options that involve variable focal lengths, autofocus capabilities, or specific operational modes (like manual mode) describe certain types of lenses, they do not define the prime lens itself, which is primarily defined by its singular focal length.