[foh-kuh l] /ˈfoʊ kəl/
of or relating to a .
of or relating to a focus
situated at, passing through, or measured from the focus
1690s, from Modern Latin focalis; see focus + -al (1).
focal fo·cal (fō’kəl)
Of or relating to a focus.
- Focal necrosis
focal necrosis n. The occurrence of numerous, small, fairly well circumscribed, foci of necrosis.
- Focal-plane shutter
[foh-kuh l pleyn] /ˈfoʊ kəl ˌpleɪn/ noun, Photography. 1. a camera shutter situated directly in front of the film.
noun, Optics. 1. a plane through a focal point and normal to the axis of a lens, mirror, or other optical system. Compare . 2. the transverse plane in a telescope where the real image of a distant view is in focus. noun 1. the plane that is perpendicular to the axis of a lens […]
noun 1. Also called principal focus. Optics. either of two points on the axis of a mirror, lens, or other optical system, one point being such that rays diverging from it are deviated parallel to the axis upon refraction or reflection by the system and the other point being such that rays parallel to the […]