Definition of focus

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Focus (n.) A central point; a point of concentration.

Lern More About Focus

Irradiation :: Irradiation (n.) The apparent enlargement of a bright object seen upon a dark ground, due to the fact that the portions of the retina around the image are stimulated by the intense light; as when a dark spot on a white ground appears smaller, or a white spot on a dark ground larger, than it really is, esp. when a little out of focus..
Focus :: Focus (n.) A point in which the rays of light meet, after being reflected or refrcted, and at which the image is formed; as, the focus of a lens or mirror..
Collimator :: Collimator (n.) A tube having a convex lens at one end and at the other a small opening or slit which is at the principal focus of the lens, used for producing a beam of parallel rays; also, a lens so used..
Camera Obscura :: Camera obscura () An apparatus in which the images of external objects, formed by a convex lens or a concave mirror, are thrown on a paper or other white surface placed in the focus of the lens or mirror within a darkened chamber, or box, so that the outlines may be traced..
Sunglow :: Sunglass (n.) A convex lens of glass for producing heat by converging the sun's rays into a focus.
Amasthenic :: Amasthenic (a.) Uniting the chemical rays of light into one focus, as a certain kind of lens; amacratic..
Focal :: Focal (a.) Belonging to,or concerning, a focus; as, a focal point..
Diaphragm :: Diaphragm (n.) A plate with an opening, which is generally circular, used in instruments to cut off marginal portions of a beam of light, as at the focus of a telescope..
Concentre :: Concentre (v. t.) To draw or direct to a common center; to bring together at a focus or point, as two or more lines; to concentrate..
Aberration :: Aberration (n.) The convergence to different foci, by a lens or mirror, of rays of light emanating from one and the same point, or the deviation of such rays from a single focus; called spherical aberration, when due to the spherical form of the lens or mirror, such form giving different foci for central and marginal rays; and chromatic aberration, when due to different refrangibilities of the colored rays of the spectrum, those of each color having a distinct focus..
Ellipse :: Ellipse (n.) An oval or oblong figure, bounded by a regular curve, which corresponds to an oblique projection of a circle, or an oblique section of a cone through its opposite sides. The greatest diameter of the ellipse is the major axis, and the least diameter is the minor axis. See Conic section, under Conic, and cf. Focus..
Eccentricity :: Eccentricity (n.) The ratio of the distance between the center and the focus of an ellipse or hyperbola to its semi-transverse axis.
Parabola :: Parabola (n.) A kind of curve; one of the conic sections formed by the intersection of the surface of a cone with a plane parallel to one of its sides. It is a curve, any point of which is equally distant from a fixed point, called the focus, and a fixed straight line, called the directrix. See Focus..
Emmetropia :: Emmetropia (n.) That refractive condition of the eye in which the rays of light are all brought accurately and without undue effort to a focus upon the retina; -- opposed to hypermetropia, myopia, an astigmatism..
Hyperbola :: Hyperbola (n.) A curve formed by a section of a cone, when the cutting plane makes a greater angle with the base than the side of the cone makes. It is a plane curve such that the difference of the distances from any point of it to two fixed points, called foci, is equal to a given distance. See Focus. If the cutting plane be produced so as to cut the opposite cone, another curve will be formed, which is also an hyperbola. Both curves are regarded as branches of the same hyperbola. See Illust. o
Focimeter :: Focimeter (n.) An assisting instrument for focusing an object in or before a camera.
Concentrate :: Concentrate (v. t.) To bring to, or direct toward, a common center; to unite more closely; to gather into one body, mass, or force; to fix; as, to concentrate rays of light into a focus; to concentrate the attention..
Focus :: Focus (n.) A point so related to a conic section and certain straight line called the directrix that the ratio of the distace between any point of the curve and the focus to the distance of the same point from the directrix is constant.
Focalize :: Focalize (v. t.) To bring to a focus; to focus; to concentrate.
Focus :: Focus (v. t.) To bring to a focus; to focalize; as, to focus a camera..
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