Zoom Ratio
Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a size ratio called optical magnification. When this number is less than one, it refers to a reduction in size, sometimes called ''de-magnification''. Typically, magnification is related to scaling up visuals or images to be able to see more detail, increasing resolution, using microscope, printing techniques, or digital processing. In all cases, the magnification of the image does not change the perspective of the image. Examples of magnification Some optical instruments provide visual aid by magnifying small or distant subjects. * A magnifying glass, which uses a positive (convex) lens to make things look bigger by allowing the user to hold them closer to their eye. * A telescope, which uses its large objective lens or primary mirror to create an image of a distant object and then allows the user to examine the image closely with a smaller eyepi ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Slide Projector
A slide projector is an optical device for projecting enlarged images of photographic slides onto a screen. Many projectors have mechanical arrangements to show a series of slides loaded into a special tray sequentially. 35 mm slide projectors, direct descendants of the larger-format magic lantern, first came into widespread use during the 1950s for slide shows as home entertainment, and for use by educational and other institutes. Reversal film created a small positive projectable image rather than the negatives used since the early days of photography; photography now produced 35mm directly viewable small colour slides, rather than large monochrome negatives. The slide images were too small for unaided viewing, and required enlargement by a projector or enlarging viewer. Photographic film slides and projectors have been replaced by image files on digital storage media shown on a projection screen by using a video projector, or displayed on a large-screen video ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Thin Lens
In optics, a thin lens is a lens (optics), lens with a thickness (distance along the optical axis between the two surfaces of the lens) that is negligible compared to the radius of curvature (optics), radii of curvature of the lens surfaces. Lenses whose thickness is not negligible are sometimes called ''thick lenses''. The thin lens approximation ignores optical effects due to the thickness of lenses and simplifies Ray tracing (physics), ray tracing calculations. It is often combined with the paraxial approximation in techniques such as ray transfer matrix analysis. Focal length The focal length, ''f'', of a lens in air is given by the lensmaker's equation: :\frac = (n-1) \left[ \frac - \frac + \frac \right], where ''n'' is the index of refraction of the lens material, ''R''1 and ''R''2 are the Radius of curvature (optics), radii of curvature of the two surfaces, and ''d'' is the thickness of the lens. Here ''R''1 is taken to be positive if the first surface is convex, and nega ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Basic Optic Geometry
Basic or BASIC may refer to: Science and technology * BASIC, a computer programming language * Basic (chemistry), having the properties of a base * Basic access authentication, in HTTP Entertainment * ''Basic'' (film), a 2003 film * Basic, one of the languages in ''Star Wars'' Music * ''Basic'' (Glen Campbell album), 1978 * ''Basic'' (Robert Quine and Fred Maher album), 1984 * ''B.A.S.I.C.'' (Alpinestars album), 2000 * ''Basic'' (Brown Eyed Girls album), 2015 * ''B.A.S.I.C.'' (The Basics album), 2019 Places * Basic, Mississippi, a community in the US * BASIC countries, Brazil, South Africa, India and China in climate change negotiations Organizations * BASIC Bank Limited, government owned bank in Bangladesh * Basic Books, an American publisher Other uses * Basic (cigarette), a brand of cigarettes manufactured by the Altria Group (Philip Morris Company) * Basic (dance move), the dance move that defines the character of a particular dance * Basic (slang), a pejorative te ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Binoculars
Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held using both hands, although sizes vary widely from opera glasses to large pedestal-mounted military models. Unlike a (monocular) telescope, binoculars give users a stereopsis, three-dimensional image: each eyepiece presents a slightly different image to each of the viewer's eyes and the parallax allows the visual cortex to generate an depth perception, impression of depth. Optical design evolution Galilean Almost from the invention of the telescope in the 17th century the advantages of mounting two of them side by side for binocular vision seems to have been explored. Most early binoculars used Galilean telescope, Galilean optics; that is, they used a convex lens, convex objective (optics), objective and a concave lens, concave eyepi ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Moon
The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar day) that is synchronized to its orbital period (Lunar month#Synodic month, lunar month) of 29.5 Earth days. This is the product of Earth's gravitation having tidal forces, tidally pulled on the Moon until one part of it stopped rotating away from the near side of the Moon, near side, making always the same lunar surface face Earth. Conversley, the gravitational pull of the Moon, on Earth, is the main driver of Earth's tides. In geophysical definition of planet, geophysical terms, the Moon is a planetary-mass object or satellite planet. Its mass is 1.2% that of the Earth, and its diameter is , roughly one-quarter of Earth's (about as wide as the contiguous United States). Within the Solar System, it is the List of Solar System objects by ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Tangent
In geometry, the tangent line (or simply tangent) to a plane curve at a given point is, intuitively, the straight line that "just touches" the curve at that point. Leibniz defined it as the line through a pair of infinitely close points on the curve. More precisely, a straight line is tangent to the curve at a point if the line passes through the point on the curve and has slope , where ''f'' is the derivative of ''f''. A similar definition applies to space curves and curves in ''n''-dimensional Euclidean space. The point where the tangent line and the curve meet or intersect is called the ''point of tangency''. The tangent line is said to be "going in the same direction" as the curve, and is thus the best straight-line approximation to the curve at that point. The tangent line to a point on a differentiable curve can also be thought of as a '' tangent line approximation'', the graph of the affine function that best approximates the original function at the given point ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Angular Size
The angular diameter, angular size, apparent diameter, or apparent size is an angular separation (in units of angle) describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the '' visual angle'', and in optics, it is the '' angular aperture'' (of a lens). The angular diameter can alternatively be thought of as the angular displacement through which an eye or camera must rotate to look from one side of an apparent circle to the opposite side. A person can resolve with their naked eyes diameters down to about 1 arcminute (approximately 0.017° or 0.0003 radians). This corresponds to 0.3 m at a 1 km distance, or to perceiving Venus as a disk under optimal conditions. Formulation The angular diameter of a circle whose plane is perpendicular to the displacement vector between the point of view and the center of said circle can be calculated using the formula :\delta = 2\arctan \left(\frac\right), in which ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Virtual Image
In optics, the ''image'' of an object is defined as the collection of Focus (optics), focus points of Ray (optics), light rays coming from the object. A ''real image'' is the collection of focus points made by Vergence (optics), converging rays, while a virtual image is the collection of focus points made by backward extensions of Beam divergence, diverging rays. In other words, a virtual image is found by tracing real rays that emerge from an optical device (lens, mirror, or some combination) backward to perceived or apparent origins of ray divergences. There is a concept ''virtual object'' that is similarly defined; an object is virtual when forward extensions of rays converge toward it. This is observed in ray tracing for a multi-lenses system or a diverging lens. For the diverging lens, forward extension of converging rays toward the lens will meet the converging point, so the point is a virtual object. For a (refracting) lens, the real image of an object is formed on the ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Inch
The inch (symbol: in or prime (symbol), ) is a Units of measurement, unit of length in the imperial units, British Imperial and the United States customary units, United States customary System of measurement, systems of measurement. It is equal to yard or of a foot (unit), foot. Derived from the Uncia (unit), Roman uncia ("twelfth"), the word ''inch'' is also sometimes used to translate similar units in other measurement systems, anthropic units, usually understood as deriving from the width of the human thumb. Standards for the exact length of an inch have varied in the past, but since the adoption of the international yard during the 1950s and 1960s the inch has been based on the metric system and defined as exactly 25.4Millimetre, mm. Name The English word "inch" () was an early borrowing from Latin ' ("one-twelfth; Roman inch; Roman ounce"). The vowel change from Latin to Old English (which became Modern English ) is known as Germanic umlaut, umlaut. The consonant c ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Real Image
{{citations needed, date=June 2019 In optics, an ''image'' is defined as the collection of focus points of light rays coming from an object. A real image is the collection of focus points actually made by converging/diverging rays, while a virtual image is the collection of focus points made by extensions of diverging or converging rays. In other words, a real image is an image which is located in the plane of convergence for the light rays that originate from a given object. Examples of real images include the image produced on a detector in the rear of a camera, and the image produced on an eyeball retina (the camera and eye focus light through an internal convex lens). In ray diagrams (such as the images on the right), real rays of light are always represented by full, solid lines; perceived or extrapolated rays of light are represented by dashed lines. A real image occurs at points where rays actually converge, whereas a virtual image occurs at points that rays appe ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Optical Power
In optics, optical power (also referred to as dioptric power, refractive power, focal power, focusing power, or convergence power) is the degree to which a lens, mirror, or other optical system converges or diverges light. It is equal to the reciprocal of the focal length of the device; high optical power corresponds to short focal length. The SI unit for optical power is the inverse metre (), which is also called a '' dioptre'' (symbol: dpt or D) when used as a unit of optical power. Explanation The optical power of a device is related to its focal length by . Converging lenses have positive optical power, while diverging lenses have negative power. When a lens is immersed in a refractive medium, its optical power and focal length change. For two or more thin lenses close together, the optical power of the combined lenses is approximately equal to the sum of the optical powers of each lens: . Similarly, the optical power of a single lens is roughly equal to the sum o ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |