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

Importantly, the lens delivers clear results across the entire frame at most focal lengths, except at 24mm. — Jim Fisher, PC Magazine, 9 July 2026

Maksutov-Cassegrain is a catadioptric design that uses two mirrors to allow a long focal length to fit into a compact optical tube. — Harry Bennett, Space.com, 11 June 2026

Full specs are still under embargo until later, but the Pocket 4P brings back the 1-inch sensor seen in the DJI Pocket 4, with a secondary camera that provides a longer focal length. — Ben Sin, Forbes.com, 15 May 2026

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