focal

UK/ˈfəʊ.kl̩/US/ˈfoʊ.kl̩/

adjectiveC1Occasional — familiar, but not everyday · #10,164 of 15,258mostly written

Focal means central, and drawing everything towards it. The focal point, focal length, a focal issue.

Focal length is the technical use and decides what a lens does: a short one takes in a wide view and a long one magnifies a narrow one. A focal point in a room is whatever the eye goes to first, which designers arrange on purpose.

Definitions of focal

1adjectivefocalCentral, and drawing everything towards it.C1
“The old market square became the focal point of the town's celebrations.”

focal is a quality.

Where it comes from

New Latin focalis comes from focus, which in Latin meant a hearth or fireplace.

New Latin
focālis
English, today
focal

New Latin focālis. by surface analysis, focus + -al.

Etymology from Wiktionary, CC BY-SA

Practise this word

focal in the wild

A positive focal length indicates that a system converges light, while a negative focal length indicates that the system diverges light.
Focal length
For more general optical systems, the focal length has no intuitive meaning; it is simply the inverse of the system's optical power.
Focal length
A wide-angle lens is also one that projects a substantially larger image circle than would be typical for a standard design lens of the same focal length.
Wide-angle lens
The angle of view and other effects of long-focus lenses are the same for telephoto lenses of the same specified focal length.
Telephoto lens
A true zoom lens or optical zoom lens is a type of parfocal lens, one that maintains focus when its focal length changes.
Zoom lens

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From Wikipedia, CC BY-SA 4.0. These sentences were written by other people about their own subjects; they are here to show the word at work, not as anybody’s opinion.

Related words

focus

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