Speakur

Word Pronunciation & Dictionary

focal length

Word Rarity Rare

Frequency: Zipf frequency 3.64 in modern English

Syllables
fo-cal length
IPA
20
Scrabble Score
11
Letters
2
Syllables
10
Unique Chars

Meaning

noun

A measure of how strongly an optical system converges or diverges light, the inverse of optical power. In the simple case of a single convex lens, it is the distance along the optical axis from the principal plane of the lens to the lens's focal point (where, for instance, the film would be placed in a camera). For more complex or multi-element optical systems, focal length need not correspond to any obvious measurable physical distance.

Inflected Forms

focal lengths (plural)

Phrases

calibrated focal length

Synonyms

focal distance

Questions

What does focal length mean?
A measure of how strongly an optical system converges or diverges light, the inverse of optical power. In the simple case of a single convex lens, it is the distance along the optical axis from the principal plane of the lens to the lens's focal point (where, for instance, the film would be placed in a camera). For more complex or multi-element optical systems, focal length need not correspond to any obvious measurable physical distance.

How to pronounce focal length

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