Magnification

For the 2001 album of progressive rock band Yes, see Magnification (album). Magnification is the seventeenth album by Progressive rock band Yes, released in 2001

Magnification is the process of enlarging something only in appearance, not in physical size. Magnification is also a number describing by which factor an object was magnified. When this number is less than one it refers to a reduction in size, sometimes called minification.

Typically magnification is related to scaling up visuals or images to be able to see more detail, increasing resolution, using optics, printing techniques, or digital processing. The visual system is the part of the Nervous system which allows organisms to see. An image (from Latin imago) or picture is an artifact usually two-dimensional that has a similar appearance to some subject &mdashusually Angular resolution describes the resolving power of any image forming device such as an optical or Radio telescope, a Microscope, a Camera Printing is a process for reproducing text and image typically with ink on Paper using a printing press Digital processing is the process of altering Digital data in any form In all cases, the magnification of the image does not change the perspective of the image. Perspective, in context of vision and Visual perception, is the way in which objects appear to the Eye based on their spatial attributes or

1 Magnification as a number (optical magnification)
- 1.1 Calculating the magnification of optical systems
- 1.2 Measurement of telescope magnification
2 Other uses
3 See also

Magnification as a number (optical magnification)

Optical magnification is the ratio between the apparent size of an object (or its size in an image) and its true size, and thus it is a dimensionless number. In Dimensional analysis, a dimensionless quantity (or more precisely a quantity with the dimensions of 1) is a Quantity without any Physical units

Linear or transverse magnification — For real images, such as images projected on a screen, size means a linear dimension (measured, for example, in millimeters or inches). In Optics, a real image is a representation of an actual object (source formed by rays of Light passing through the Image. Inches redirects here To see the Les Savy Fav album see Inches.

Angular magnification — For optical instruments with an eyepiece, the linear dimension of the image seen in the eyepiece (virtual image in infinite distance) cannot be given, thus size means the angle subtended by the object at the focal point (angular size). An optical instrument either processes Light waves to enhance an image for viewing or analyzes light waves (or Photons to determine one of a number of characteristic For the device for looking through a camera see Viewfinder. An eyepiece, or ocular lens, is a type of lens that is attached In Optics, a virtual image is an image in which the outgoing rays from a point on the object never actually intersect at a point The angular diameter of an object as seen from a given position is the "visual diameter" of the object measured as an angle Strictly speaking, one should take the tangent of that angle (in practice, this makes a difference only if the angle is larger than a few degrees). Circle-trig6svg|300px|thumb|right|All of the Trigonometric functions of an angle θ can be constructed geometrically in terms of a unit circle centered at O. Thus, angular magnification is defined as

$\mathrm{MA}=\frac{\tan \varepsilon}{\tan \varepsilon_0}$ ,

where ${\varepsilon_0}$ is the angle subtended by the object at the front focal point of the objective and ${\varepsilon}$ is the angle subtended by the image at the rear focal point of the eyepiece.

Example: The angular size of the full moon is 0. The angular diameter of an object as seen from a given position is the "visual diameter" of the object measured as an angle 5°, in binoculars with 10x magnification it appears to subtend an angle of 5°, which is roughly 1/10th of the field of view of typical eyepieces. Binocular telescopes, or binoculars (also known as field glasses are two identical or Mirror - symmetrical telescopes mounted side-by-side and For the device for looking through a camera see Viewfinder. An eyepiece, or ocular lens, is a type of lens that is attached

By convention, for magnifying glasses and optical microscopes, where the size of the object is a linear dimension and the apparent size is an angle, the magnification is the ratio between the apparent (angular) size as seen in the eyepiece and the angular size of the object when placed at the conventional closest distance of distinct vision of 25 cm from the eye. magnifying glass (called a hand lens in laboratory contexts is a convex lens which is used to produce a magnified Image of an object A microscope ( Greek: ( micron) = small + ( skopein) = to look or see is an instrument for viewing objects that are

Optical magnification is sometimes referred to as "power" (for example "10× power"), although this can lead to confusion with optical power. Optical power ( dioptric power or refractive power) is the degree to which a lens or Mirror converges or diverges light

Calculating the magnification of optical systems

Single lens: The linear magnification of a thin lens is

$M = {f \over f-d_o}$

where

f

is the focal length and

d o

is the distance from the lens to the object and

h o

is the height of the object. A lens is an optical device with perfect or approximate Axial symmetry which transmits and refracts Light, converging or diverging In Optics, a thin lens is a lens with a thickness (distance along the Optical axis between the two surfaces of the lens that is negligible compared Note that for real images,

M

is negative and the image is inverted. In Optics, a real image is a representation of an actual object (source formed by rays of Light passing through the Image. For virtual images,

M

is positive and the image is upright. In Optics, a virtual image is an image in which the outgoing rays from a point on the object never actually intersect at a point With

d i

the distance from the lens to the image and

h i

being the height of the image, the magnification can also be written as:

$M = -{d_i \over d_o} = {h_i \over h_o}$

Note again that a negative magnification implies an inverted image.

Photography: in photography, the image projected onto the film or image sensor is always a real image. Photography (fә'tɒgrәfi or fә'tɑːgrәfi (from Greek φωτο and γραφία is the process and Art of recording pictures by means of capturing This article is mainly concerned with Still photography film For Motion picture film please see Film stock. An image sensor is a device that converts an optical image to an electric signal In Optics, a real image is a representation of an actual object (source formed by rays of Light passing through the Image. The image is thus inverted, but this is usually corrected in the viewfinder and is not relevant to the final printed or digitized image. This article is about the definition for the short story by Raymond Carver, see Viewfinder (short story In Photography, a The positive sign convention is typically used, thus magnification is defined as:

$M = +{d_i \over d_o}$

Telescope: The linear magnification is given by

$M= {f_o \over f_e}$

where

f o

is the focal length of the objective lens and

f e

is the focal length of the eyepiece. A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. The focal length of an optical system is a measure of how strongly it converges (focuses or diverges (diffuses Light. An objective in Optics is the lens or Mirror in a Microscope, Telescope, camera or other optical instrument The focal length of an optical system is a measure of how strongly it converges (focuses or diverges (diffuses Light. For the device for looking through a camera see Viewfinder. An eyepiece, or ocular lens, is a type of lens that is attached The angular magnification is given by

$\mathrm{MA}= {f_o \over f_e}$

Magnifying glass: The angular magnification of a magnifying glass depends on how the glass and the object are held, relative to the eye. magnifying glass (called a hand lens in laboratory contexts is a convex lens which is used to produce a magnified Image of an object If the lens is held such that its front focal point is on the object being viewed, the relaxed eye can view the image with angular magnification

$\mathrm{MA}={25\ \mathrm{cm}\over f}\quad.$

If instead the lens is held very close to the eye, and the object is placed close to the lens, a larger angular magnification can be obtained, approaching

$\mathrm{MA}={25\ \mathrm{cm}\over f}+1\quad .$

Here,

f

is the focal length of the lens in centimeters. The focal length of an optical system is a measure of how strongly it converges (focuses or diverges (diffuses Light. A lens is an optical device with perfect or approximate Axial symmetry which transmits and refracts Light, converging or diverging The constant 25 cm is an estimate of the "near point" distance of the eye—the closest distance at which the eye can focus.

Microscope: The angular magnification is given by

$\mathrm{MA}=M_o \times M_e$

where

M o

is the magnification of the objective and

M e

the magnification of the eyepiece. A microscope ( Greek: ( micron) = small + ( skopein) = to look or see is an instrument for viewing objects that are The magnification of the objective depends on its focal length

f o

and on the distance

d

between objective back focal plane and the focal plane of the eyepiece (called the tube length):

$M_o={d \over f_o}$ . The focal length of an optical system is a measure of how strongly it converges (focuses or diverges (diffuses Light. The cardinal points and the associated cardinal planes are a set of special points and planes in an optical system which help in the analysis For the device for looking through a camera see Viewfinder. An eyepiece, or ocular lens, is a type of lens that is attached

The magnification of the eyepiece depends upon its focal length

f e

and can be calculated by the same equation as that of a magnifying glass (above).

Note that both astronomical telescopes as well as simple microscopes produce an inverted image, thus the equation for the magnification of a telescope or microscope is often given with a minus sign. The plus and minus signs ( + and &minus) are Mathematical symbols used to represent the notions of positive and negative as well as the operations

Measurement of telescope magnification

Measuring the actual angular magnification of a telescope is difficult, but it is possible to use the reciprocal relationship between the linear magnification and the angular magnification, since the linear magnification is constant for all objects.

The telescope is focussed correctly for viewing objects at the distance for which the angular magnification is to be determined and then the object glass is used as an object the image of which is known as the Ramsden disc. In Optics, the exit pupil is a virtual Aperture in an optical system The diameter of this may be measured using an instrument known as a Ramsden dynamometer which consists of a Ramsden eyepiece with micrometer cross hairs in the back focal plane. This is mounted in front of the telescope eyepiece and used to measure the diameter of the Ramsden disc. This will be much smaller than the object glass diameter, which gives the linear magnification (actually a reduction), the angular magnification can be determined from

MA = 1 / M = D Objective / D Ramsden

Other uses

One can also magnify sounds (see amplification). Generally an amplifier or simply amp, is any device that changes usually increases the amplitude of a signal.
Magnification can also be used as a generalized term for increasing the detail or vividness of something: ideas, emotions, etc. iDeaS is a Nintendo DS Emulator for Microsoft Windows and Linux, using GTK+. An emotion is a mental and physiological state associated with a wide variety of feelings thoughts and behaviours
A magnification factor is sometimes misused on the internet to describe the scale of an image e. g. from a microscope. Magnification is not the correct term here because the size of the displayed image cannot be controlled. A better practice is to include a scale bar or other object of known size in the image. In certain art-pictures, such as Nikon Small World Gallery, scale bars are undesirable for aesthetic reasons - in such cases, a caption is often used stating the size of some apparent feature or stating the field size of the original image.

Dictionary

-noun

The act of magnifying; enlargement; exaggeration.

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Contents

Magnification as a number (optical magnification)

Calculating the magnification of optical systems

Measurement of telescope magnification

Other uses

See also

Dictionary

magnification

-noun