focal lengthnoun [ C usually singular ]uk /ˌfəʊ.kəl ˈleŋθ/ us /ˌfoʊ.kəl ˈleŋθ/ specialized
Examples from literature
- On the other hand, the eye-glass must not be of such small focal length that the image appears indistinct and contorted, or dull for want of light.
- The rapidity of a lens depends mainly on its aperture and its focal length.
- The speed of a photographic lens depends on the ratio of the effective aperture to the focal length.
- To overcome this obstacle to clear vision, and also to secure magnification, the focal lengths of the instruments were greatly extended.
- We may apply eye-glasses of different focal length.