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Focal length. The focal point F and focal length f of a positive (convex) lens, a negative (concave) lens, a concave mirror, and a convex mirror. The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a ...
In geometrical optics, a focus, also called an image point, is a point where light rays originating from a point on the object converge. [1] Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle. This non-ideal focusing may be caused by aberrations of the imaging optics.
f-number. Diagram of decreasing apertures, that is, increasing f-numbers, in one-stop increments; each aperture has half the light-gathering area of the previous one. An f-number is a measure of the light-gathering ability of an optical system such as a camera lens. It is calculated by dividing the system's focal length by the diameter of the ...
Earthquakes. The epicenter ( / ˈɛpɪˌsɛntər / ), epicentre, or epicentrum [1] in seismology is the point on the Earth 's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates.
The ampersand can be used to indicate that the "and" in a listed item is a part of the item's name and not a separator (e.g. "Rock, pop, rhythm & blues and hip hop"). The ampersand may still be used as an abbreviation for "and" in informal writing regardless of how "and" is used.
The following table shows which essential oils claim to boost energy, mood, or creativity. Future research will need to specify and study these claims. Essential oil. Claimed benefits. bergamot ...
In general, the smaller the aperture (the larger the f-number), the greater the distance from the plane of focus the subject matter may be while still appearing in focus. The lens aperture is usually specified as an f-number, the ratio of focal length to effective aperture diameter (the diameter of the entrance pupil). A lens typically has a ...
Focus (geometry) Point F is a focus point for the red ellipse, green parabola and blue hyperbola. In geometry, focuses or foci ( / ˈfoʊkaɪ /; sg.: focus) are special points with reference to which any of a variety of curves is constructed. For example, one or two foci can be used in defining conic sections, the four types of which are the ...