focal length

noun

: the distance of a focus from the surface of a lens or curved mirror

Examples of focal length in a Sentence

Recent Examples on the Web

The ultrawide has a 12mm equivalent focal length and a wide 122-degree field of view, and the telephoto has a 3x optical periscopic lens with a Sony Lytia sensor, a 71mm equivalent focal length, and OIS. —Eric Zeman, PC Magazine, 1 May 2026

Supporting this is a multi-camera array designed to work across various focal lengths. —New Atlas, 27 Apr. 2026

Measuring over two feet long, the lens had a Goldilocks quality: the right focal length and aperture that would allow the director to get the entirety of the sun in the frame, while still physically fitting the Mitchell-Fries camera. —Mia Galuppo, HollywoodReporter, 15 Apr. 2026

Bloch captured the images on a Canon R5 II, with a 600 mm f/4 prime lens and a 2x teleconverter, for an effective 1,200mm focal length. —Robert A. Cronkleton march 31, Kansas City Star, 31 Mar. 2026

Word History

First Known Use

1682, in the meaning defined above

Rhymes for focal length

• strength

Kids Definition

focal length

noun

: the distance of a focus from the surface of a lens or inwardly-curved mirror

Medical Definition

focal length

noun

-ˌleŋ(k)th 

: the distance of a focus from the surface of a lens or concave mirror

—symbol f