focal length


: 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 Pro Max camera boasts a 5x optical zoom, and allows for 120mm focal length. Byrachyl Jones, Fortune, 12 Sep. 2023 Because digital sensors are much smaller, a shorter focal length is required, demanding in turn a much smaller pinhole. IEEE Spectrum, 27 Aug. 2023 There’s noticeable natural bokeh (depth-of-field blur) in photos due to the focal length, image sensor size (1/1.3-inch) and fast f/1.5 aperture. Ben Sin, Forbes, 18 Dec. 2022 This creates enough separation between the lens and the sensor to enable the longer focal length. Jay Peters, The Verge, 18 Sep. 2023 For you camera geeks, it’s got a 120 millimeter focal length and f/2.8 aperture. WSJ, 12 Sep. 2023 Traditional pinhole cameras have relatively long focal lengths because of the size of a frame of film, allowing for larger and easier-to-make pinholes. IEEE Spectrum, 27 Aug. 2023 Telephoto lenses offer a longer focal length than standard lenses and provide a narrower field of view. Brandon Russell, Popular Mechanics, 29 Mar. 2023 Alongside its 1-inch-type 50-megapixel main sensor with 23mm focal length, the X90 Pro also has an additional 50-megapixel sensor with a longer 50mm-equivalent focal length for portraits, and a 12-megapixel ultrawide camera. Jon Porter, The Verge, 3 Feb. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'focal length.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1682, in the meaning defined above

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

Dictionary Entries Near focal length

Cite this Entry

“Focal length.” Dictionary, Merriam-Webster, Accessed 29 Nov. 2023.

Kids Definition

focal length

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

Medical Definition

focal length

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

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