Definition of Focal ratio

1. Noun. The ratio of the focal length to the diameter of a (camera) lens system.

Exact synonyms: F Number, Speed, Stop Number
Generic synonyms: Ratio

Lexicographical Neighbors of Focal Ratio

focal glomerulonephritis
focal illumination
focal infection
focal interval
focal length
focal lengths
focal lymphocytic thyroiditis
focal metastatic disease
focal motor seizure
focal necrosis
focal nephritis
focal nodular hyperplasia
focal plane
focal point
focal points
focal ratio (current term)
focal reaction
focal sclerosing glomerulopathy
focal sclerosis
focal sclerosis with hyalinosis
focal segmental glomerulosclerosis
focal seizure
focal spot
focal spot size

Literary usage of Focal ratio

Below you will find example usage of this term as found in modern and/or classical literature:

1. A System of Applied Optics: Being a Complete System of Formulæ of the Second by H. Dennis Taylor (1906)
"A very sli»ht increase in the focal ratio over the above 1'875 : 1 will render the equation insoluble, the nearest approach to freedom from spherical ..."

2. The Encyclopedia Britannica: A Dictionary of Arts, Sciences, Literature and by Hugh Chisholm (1911)
"... but still not quite к> good as the results obtained by using the combination of two convexo-plane lenses of the focal ratio 2 to I. image viewed by the ..."

3. The Astrophysical Journal by American Astronomical Society, University of Chicago (1905)
"... having a focal ratio of less than £. As indicated, the telescope is really triple in character, ..."

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