A lens that is one focal length (50mm) is called

• A. Zoom Lens
• B. Wide Angle
• C. Telephoto
• D. Prime Lens

Answer: (D)

A fixed focal length defines a prime lens. Because it covers only one focal length, you can’t zoom in or out; you frame by moving your position or changing distance to the subject. A 50mm lens is a prime lens, meaning it has a single, constant focal length.

Prime lenses are often preferred for their sharpness, simpler optical design, and often wider maximum apertures. On a full-frame sensor, 50mm gives a natural, “normal” perspective, close to human vision; on crop sensors it behaves a bit more like a tighter view, but it remains a prime because its focal length doesn’t change.

The other terms describe either the ability to change focal length (a zoom lens) or the field of view associated with different focal lengths (wide-angle for short focal lengths, telephoto for long focal lengths), rather than the fixed nature of the lens.