a plane through a focal point and normal to the axis of a lens, mirror, or other optical system.
the transverse plane in a telescope where the real image of a distant view is in focus.
the plane that is perpendicular to the axis of a lens or mirror and passes through the focal point
the plane in a telescope, camera, or other optical instrument in which a real image is in focus
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 […]
noun, Optics, Photography. 1. . noun 1. (photog) another name for f-number
- Focal reaction
focal reaction n. A limited reaction that occurs at the point of entrance of an infecting organism or of an injection. Also called local reaction.
- Focal segmental glomerulosclerosis
focal segmental glomerulosclerosis n. Segmental collapse of glomerular capillaries with thickened basement membranes and increased mesangial matrix, seen sometimes in nephrotic syndrome or mesangial proliferative glomerulonephritis.