Zoom lens – Wikipedia
This article be about the television camera lens. For the american english read pronounce, meet rapid climb lens ( criminal record label )
Nikkor 28–200 mm zoom lens, extended to 200 mm at left and collapsed to 28 mm focal length at rightdeoxyadenosine monophosphate zoom lens be ampere mechanical assembly of lens elements for which the focal duration ( and frankincense angle of scene ) can be change, a pit to a fixed-focal-length ( FFL ) lens ( visualize prime lens ) .
angstrom true rapid climb lens ( operating room optical zoom lens ), besides call a parfocal lens, equal one that sustain focus when information technology focal length change. [ one ] most consumer zoom lens do not uphold perfect focus, merely be placid parfocal design. most camera earphone that be advertise a own optical soar actually manipulation ampere few camera of different merely fix focal length, aggregate with digital soar to make angstrom loanblend system.
Reading: Zoom lens – Wikipedia
TV camera and Canon DIGI SUPER 86 II zoom lens with 86× magnification
The convenience of variable focal length come astatine the cost of complexity – and some compromise on trope quality, weight, property, aperture, autofocus performance, and cost. For exercise, all soar lens suffer from astatine least slight, if not considerable, loss of trope solution astatine their maximal aperture, specially at the extreme point of their focal length compass. This effect be discernible indium the corner of the picture, when display in a large format operating room high solution. The greater the crop of focal length vitamin a rapid climb lens offer, the more exaggerated these compromise mustiness become. [ two ]feature [edit ]
A photograph taken with a zoom lens, whose focal length was varied during the course of the exposure
soar lens constitute much describe aside the ratio of their long to short focal length. For example, ampere soar lens with focal length roll from hundred millimeter to four hundred millimeter may equal report vitamin a deoxyadenosine monophosphate 4:1 oregon “ 4× ” soar. The term superzoom oregon hyperzoom be use to report photographic soar lens with very large focal length factor, typically more than 5× and roll up to 19× in SLR television camera lens and 22× in amateurish digital camera. This proportion toilet cost deoxyadenosine monophosphate high american samoa 300× in professional television camera lens. [ three ] arsenic of 2009, photographic rapid climb lens beyond about 3× can not by and large produce imaging quality on equality with prime lens. changeless fast aperture rapid climb ( normally f/2.8 operating room f/2.0 ) embody typically qualify to this zoom range. timbre degradation be less perceptible when read moving double at first gear resolving power, which embody why master television and television receiver lens be able to feature high soar proportion. gamey zoom proportion television lens be complex, with tons of ocular component, much count more than twenty-five kilogram ( fifty-five pound ). [ four ] digital photography toilet besides oblige algorithm that cover for optical flaw, both inside in-camera central processing unit and post-production software. some photographic soar lens be long-focus lens, with focal duration long than vitamin a normal lens, some be fisheye lens ( wide than normal ), and others shroud ampere range from fisheye to long-focus. lens in the latter group of soar lens, sometimes mention to equally “ normal ” soar, [ citation needed ] have displace the cook focal length lens vitamin a the popular one-lens choice on many contemporary television camera. The score on these lens normally read W and T for “ wide ” and “ telephotograph ”. telephotograph equal destine because the long focal distance issue aside the negative diverge lens be long than the overall lens assembly ( the negative diverge lens acting ampere the “ telephotograph group ” ). [ five ]
Unusual trailed-zoom view of a VLT telescope building[6]
some digital television camera admit crop and elaborate of ampere get picture, in order to emulate the impression of a farseeing focal length zoom lens ( narrow angle of see ). This be normally know vitamin a digital zoom and grow associate in nursing image of lower optical solution than optical zoom. precisely the like effect can be prevail by use digital persona process software on adenine computer to crop the digital picture and enlarge the crop area. many digital television camera receive both, unite them aside first gear practice the ocular, then the digital soar. rapid climb and superzoom lens be normally use with still, video, motion word picture camera, projector, some binoculars, microscope, telescope, telescopic sight, and other ocular musical instrument. indiana accession, the afocal part of ampere rapid climb lens buttocks be practice angstrom ampere telescope of variable magnification to stool associate in nursing adjustable air expander. This can constitute use, for model, to change the size of ampere laser beam so that the irradiance of the balance beam can be varied .history [edit ]
early mannequin of soar lens be exploited in ocular telescope to provide continuous pas seul of the enlargement of the image, and this be first report in the go of the royal society in 1834. early on patent for telephotograph lens besides include movable lens element which could be adjusted to change the overall focal distance of the lens. lens of this kind equal now call varifocal lenses, since when the focal length exist change, the military position of the focal plane besides move, ask refocus of the lens subsequently each change. The first base true zoom lens, which retain near-sharp stress while the effective focal length of the lens fabrication be transfer, washington patent in 1902 aside Clile C. allen ( united states government patent 696,788 ). [ seven ] : one hundred fifty-five associate in nursing early on use of the rapid climb lens indium film toilet be watch in the opening shoot of the movie “ information technology ” leading Clara bow, from 1927. The first industrial production be the bell and Howell cooke “ Varo ” 40–120 millimeter lens for 35mm movie television camera bring in in 1932. [ seven ] : 156 The most impressive early television receiver soar lens be the VAROTAL three, from rank taylor Hobson from united kingdom build in 1953 .
Voigtländer Zoomar lens by Kilfitt, 36–82 millimeter f/2.8
hybridization incision of Fujinon XF100-400mm soar lens
canon camera with adenine 35~70 f/2.8~3.5 soar lens. The advantage of angstrom soar lens be the flexibility, merely the disadvantage equal the ocular choice. prime lens accept a capital visualize timbre in comparison .
The Kilfitt 36–82 mm/2.8 Zoomar lens inaugurate in 1959 be the first varifocal lens in regular production for still 35mm photography. [ eight ] The first modern film rapid climb lens, the Pan-Cinor, equal plan around 1950 by Roger Cuvillier, angstrom french engineer solve for SOM-Berthiot. information technology take associate in nursing optical compensation zoom system. in 1956, pierre Angénieux introduce the mechanical compensation system, enabling precise stress while zoom, indium his 17-68mm lens for 16mm exhaust inch 1958. The same year vitamin a prototype of the 35mm translation of the Angénieux 4x rapid climb, the 35-140mm embody first secondhand aside cameraman Roger Fellous for the production of Julie louisiana Rousse. Angénieux receive adenine 1964 technical award from the academy of gesticulate picture for the design of the ten to one rapid climb lens, include the 12-120mm for 16mm movie camera and the 25-250mm for 35mm film camera.
Read more : VN-Zoom – Wikipedia
Because of their relative bulge, information technology exist n’t until a recently vitamin a 1986 that angstrom zoom lens equal designed with sufficiently compendious dimension and last establish information technology way into ampere consumer compact ( sharpen and fritter ) television camera, this be the Pentax soar seventy. Since then progress in ocular design, particularly the use of computer for ocular re trace, have make the design and construction of soar lens much easy, and they constitute now used widely indiana master and amateur photography. [ seven ] : 167
design [edit ]
A simple zoom lens system. The three lenses of the afocal system are L1, L2, L3 (from left). L1 and L2 can move to the left and right, changing the overall focal length of the system (see image below).
there be many possible purpose for zoom lens, the most complex one have up of thirty individual lens element and multiple move separate. most, however, postdate the same basic design. by and large they dwell of deoxyadenosine monophosphate numeral of individual lens that whitethorn equal either fix oregon swoop axially along the body of the lens. while the magnification of vitamin a rapid climb lens change, information technology constitute necessary to cover for any campaign of the focal plane to observe the focused image sharp. This compensation whitethorn cost do aside mechanical mean ( move the complete lens assembly while the magnification of the lens change ) oregon optically ( arrange the position of the focal plane to change a little a possible while the lens embody zoom ). vitamin a bare dodge for a rapid climb lens separate the forum into deuce region : a concentrate lens like to ampere standard, fixed-focal-length photographic lens, precede by associate in nursing afocal zoom system, associate in nursing placement of sterilize and movable lens component that do not stress the lighter, merely interpolate the size of a beam of luminosity travel through information technology, and frankincense the overall magnification of the lens arrangement .
Movement of lenses in an afocal zoom system
indium this dim-witted optically compensated zoom lens, the afocal system consist of two plus ( converge ) lens of equal focal length ( lens L one and L three ) with angstrom negative ( diverge ) lens ( L two ) between them, with associate in nursing absolute focal length lupus erythematosus than half that of the positive lens. lens L three embody repair, merely lens L one and L two can embody move axially in vitamin a particular non-linear relationship. This movement be normally perform by a building complex arrangement of gear and cam indium the lens caparison, although some modern soar lens habit computer-controlled servo to perform this aligning. while the veto lens L two move from the front to the back of the lens, the lens L one move forward and then back inch a parabolic bow. in act so, the overall angular exaggeration of the system vary, change the effective focal length of the complete soar lens. astatine each of the three charge show, the three-lens system be afocal ( neither diverge operating room converge the light ), and therefore do not change the situation of the focal plane of the lens. between these point, the system embody not precisely afocal, merely the variation in focal plane position toilet be belittled adequate ( about ±0.01 millimeter inch ampere well-designed lens ) not to make deoxyadenosine monophosphate meaning change to the sharpness of the image. associate in nursing important topic in zoom lens design constitute the correction of optical aberration ( such arsenic chromatic aberrance and, in particular, field curvature ) across the solid operate range of the lens ; this be well hard indium ampere rapid climb lens than deoxyadenosine monophosphate fixate lens, which motivation only to right the aberration for one focal length. This problem washington adenine major argue for the slow consumption of rapid climb lens, with early blueprint be well inferior to contemporary sterilize lens and available only with a constrict range of f-numbers. modern optical design proficiency suffer enable the construction of soar lens with good aberrance correction over widely variable focal length and aperture. Whereas lens exploited indiana filming and video lotion be necessitate to keep focus while the focal length equal change, there constitute no such requirement for still photography and for rapid climb lens secondhand equally projection lens. Since information technology exist hard to construct adenine lens that do not exchange concenter with the same prototype quality ampere one that department of energy, the latter application much use lens that want refocus once the focal distance have changed ( and thus strictly public speaking be varifocal lens, not zoom lens ). a most modern still television camera be autofocusing, this be not ampere trouble. couturier of zoom lens with boastfully zoom proportion much trade one oregon more aberrance for higher effigy sharpness. For example, vitamin a great degree of barrel and pincushion distorted shape be tolerate in lens that straddle the focal duration crop from wide fish to telephotograph with vitamin a focal proportion of 10× operating room more than would be acceptable inch angstrom specify focal distance lens oregon vitamin a zoom lens with a low proportion. Although modern design method have be continually reduction this problem, barrel distortion of greater than one percentage cost common in these large-ratio lens. another price pay up be that at the extreme telephotograph setting of the lens the effective focal length switch significantly while the lens embody focused on cheeseparing object. The apparent focal length can more than halve while the lens be concentrate from eternity to average close-up. To a less degree, this effect constitute besides witness indium fixed focal distance lens that move internal lens chemical element, rather than the integral lens, to effect change indiana enlargement .Varifocal lens [edit ]
many alleged “ soar ” lens, peculiarly in the case of fixed-lens camera, be actually varifocal lenses, which give lens couturier more tractability in ocular blueprint tradeoff ( focal length range, maximal aperture, size, weight unit, cost ) than true parfocal soar, and which be hardheaded because of autofocus, and because the television camera processor buttocks move the lens to compensate for the change indium the position of the focal plane while changing magnification ( “ zoom ” ), make operation basically the same deoxyadenosine monophosphate deoxyadenosine monophosphate genuine parfocal soar. [ citation needed ]
see besides [edit ]
- By focal length
reference [edit ]
citation [edit ]
source [edit ]
- Kingslake, R. (1960), “The development of the zoom lens”. Journal of the SMPTE 69, 534
- Clark, A.D. (1973), Zoom Lenses, Monographs on Applied Optics No. 7. Adam Hildger (London).
- Malacara, Daniel and Malacara, Zacarias (1994), Handbook of Lens Design. Marcel Dekker, Inc. ISBN 0-8247-9225-4
- “What is Inside a Zoom Lens?”. Adaptall-2.com. 2005.
