Which lens type has a fixed focal length and cannot zoom?

• A. Zoom lens
• B. Macro lens
• C. Prime lens
• D. Fish-eye lens

Answer: (C)

The idea here is distinguishing between a fixed focal length and a zoom. A prime lens has a single focal length, so there’s no zoom mechanism to change the angle of view; you adjust framing by moving toward or away from the subject (or by cropping later). That fixed focal length is what defines a prime lens and is why it’s the best answer when the question asks for something that cannot zoom.

Zoom lenses, in contrast, cover a range of focal lengths in one barrel, letting you change the field of view without moving. Macro lenses are built for close-up reproduction and high magnification, focusing on near distances; while you can find both prime and zoom macrolenses, the key point is their close-focusing capability rather than a fixed focal length. Fish-eye lenses are ultra-wide and produce distinctive distortion, and they can be either prime or zoom; their defining trait isn’t fixed focal length.

So the lens with a fixed focal length and no zoom is a prime lens.