focal plane

noun

: a plane that is perpendicular to the axis of a lens or mirror and passes through the focus

Examples of focal plane in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The bokeh mode impressed me by keeping my chair sharp while still blurring the rest of the background, as a camera with a limited focal plane would do. PCMAG, 19 Mar. 2025 To form a perfect image on your retina, your eye forces these flat waves to curve inward, so that the waves converge at one point on the focal plane behind your eye's lens. Sidd Bikkannavar, IEEE Spectrum, 26 Feb. 2010 Normally, these telescopes produce a curved focal plane that doesn't match the flat surface of a CCD camera sensor. Gemma Lavender, Space.com, 15 Jan. 2025 That makes the full panoply hard to study simultaneously because much of it takes place above or below the microscope’s narrow focal plane. The Physics Arxiv Blog, Discover Magazine, 2 Dec. 2024 Cons of Iron Sights for Hunters Unlike optical sights, which put the reticle and the target in the same focal plane and require your eye to focus on only that plane, iron sights involve three focal planes: rear sight, front sight, and target. David E. Petzal, Field & Stream, 30 Jan. 2023 The focal plane took six months to assemble. Ashley Strickland, CNN, 8 Sep. 2020 That said, the a7R V sports a pro-grade mechanical focal plane shutter, with support for electronic first curtain, but those are long-running features in the series. PCMAG, 31 Oct. 2022 Focusing is fast and accurate, the focal plane seems bigger, there’s no discernible shutter lag, and most of all: the pictures look better. Dieter Bohn, The Verge, 21 Jan. 2021

Word History

First Known Use

1840, in the meaning defined above

Time Traveler
The first known use of focal plane was in 1840

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Cite this Entry

“Focal plane.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/focal%20plane. Accessed 25 Mar. 2025.

Medical Definition

focal plane

noun
: a plane that is perpendicular to the axis of a lens or mirror and passes through the focus
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