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
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The focal length is a short telephoto for the sensor size, with an angle of view that's just about the same as an 85mm full-frame prime. PCMAG, 5 Mar. 2025 The lens also has a focal length of 35mm, which is a more optimum focal length for photography. Ben Sin, Forbes, 3 Mar. 2025 That’s fancy branding for how the phone uses one high-resolution sensor to simulate multiple focal lengths. Jennifer Jolly, USA TODAY, 28 Feb. 2025 The cylindrical top section is home to a 3.4-mm wide-angle lens with a focal length of 6.7 mm (45 mm equiv) and a 35-mm telephoto with a focal length of 150 mm (737 mm equiv), the latter made with low-dispersion glass. New Atlas, 28 Feb. 2025 See All Example Sentences for focal length

Word History

First Known Use

1682, in the meaning defined above

Time Traveler
The first known use of focal length was in 1682

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Cite this Entry

“Focal length.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/focal%20length. Accessed 13 Mar. 2025.

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

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