noun
- The ratio of the focal length to the diameter of a (camera) lens system.
- synonyms: f number, stop number, speed
WordNet 3.0 © 2006 by Princeton University
| APA | WordNet. (2010). focal ratio. Retrieved September 21, 2026, from http://smartdefine.org/focal_ratio/definitions/1244643 |
| Chicago | WordNet. 2010. "focal ratio" http://smartdefine.org/focal_ratio/definitions/1244643 (accessed September 21, 2026). |
| Harvard | WordNet 2010, focal ratio, Smart Define, viewed 21 September, 2026, <http://smartdefine.org/focal_ratio/definitions/1244643>. |
| MLA | WordNet. "focal ratio" 23 October 2010. Web. 21 September 2026. <http://smartdefine.org/focal_ratio/definitions/1244643> |