focal ratio

Noun

Meaning

the ratio of the focal length to the diameter of a (camera) lens system

Source: WordNet

Synonyms

speed f-number stop number

Hypernyms

ratio

Examples

The effective aperture is expressed by an f-number or f-stop (derived from focal ratio ), which is proportional to the ratio of the focal length to the diameter of the aperture. Source: Internet

The focal ratio (f-number, the ratio of the focal length to the dish diameter) of typical parabolic antennas is 0.25 - 0.8, compared to 3 - 8 for parabolic mirrors used in optical systems such as telescopes. Source: Internet

Close letter words and terms

focal points focal position focal power focal segmental glomerulosclerosis focal seizure focalin xr