focal ratio


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focal ratio

n
(Photography) photog another name for f-number
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.focal ratio - the ratio of the focal length to the diameter of a (camera) lens system
ratio - the relative magnitudes of two quantities (usually expressed as a quotient)
References in periodicals archive ?
Another consideration is the focal ratio or 'speed' of the lens: f/1.
The fibre uses a large core-to-clad ratio to reduce stress transfer to its core, maintaining laser beam quality and improving focal ratio degradation in lasers used for cutting, welding, drilling, soldering and marking.
The focal ratio is considered critical because it holds expenses down by reducing the height of the building needed to house the telescope.