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`Document Display
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`* NOTICE *
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`RAL
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`IPO and INPEY are not responsible for any damages caused by the use of this
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`translation.
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`i. This docurnent has been translated by cornputer. So the translation may not reflect
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`the original precisely.
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`2,** shows a word which cannot be translated.
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`3. In the drawings, any words are not translated.
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`
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`(19) [Publication country] IP
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`(12) [Kind of official gazette] A
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`{Li} [Publication nurnber] 2006178244
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`(43) [Date of publication of application] 20060706
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`(54) [Title of the invention] ZOOM LENS
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`(51) [International Patent Classification]
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`GO2B 15/20
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`(2006.01)
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`GO2B 13/18
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`(2006.01)
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`[FT]
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`GO28 15/20
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`G028 13/18
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`(21) [Application number] 2004372461
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`{22} [Fling date] 20041224
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`{71) [Applicant]
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`[Name] NIBEC COPAL CORP
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`(72) [Inventor]
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`{Full name} IKEDA SHIN
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`iTheme code (reference)]
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`2H087
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`{F-term (reference) |
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`2HOS7KAQZ
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`2HO875A853
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`2HO875A55
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`2HO87S5A63
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`2HO87SA64
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`(57) [Overview]
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`PROBLEM TO BE SOLVED: To pravide a zoom lens which has wide angle of view a
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`nd with which a high zoom ratio is assured.
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`SOLUTION: The zoom lens is equipped with a first Jans group I having positive ref
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`ractive power, a second lens group II having negative refractive power, a third fe
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`ns group HI having positive refractive power, a fourth lens group IV having negat
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`ive refractive power, and a fifth lens group V having positive refractive power, int
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`he order from the object side to the image face side, in which the first lens group
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`T is fixed, and zooming from a wide angle end to a telephoto end is performed by
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`moving the second Jens group I from the object side to the image plane side, an
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`dg the aberration correction accompanying the zoarning is performed by moving th
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`e third lens group II, the fourth Jens group IV and the fifth lens group V. As a res
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`ult, the zoom lens of the high optical performance with which the wide angle ofvi
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`ew as wide as about 75° can be obtained at a wide angle and, a variable power ra
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`tio (zoom ratio} of about 5 times can be assured and the various aberrations are
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`well corrected over the entire area of a zoom range can be obtained.
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`[Patent Claims]
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`{Claim 1]
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`A l fens group having positive refractive power, a 2 lens croup having necative r
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`efractive power, a 3 lens group having positive refractive power, a 4 jiens group h
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`aving negative refractive power, and a 5 lens group having positive refractive po
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`wer are provided in this order frorn the object side toward the image side.
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`The 1 fens group is fixed, the 2 lens group is moved from the object side to the i
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`mage plane side, zooming from the wide angie end to the telephoto end is perfor
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`med, and the 3 lens group, the 4 lens group, and the 5 lens group are moved to
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`perform aberration correction accompanying zooming.
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`The zoom lens characterized by things.
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`[Claim 2]
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`The i fens group comprises a single 1 lens having positive refractive power.
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`The zoom lens according to claim 1, wherein, when the focal length of the lens sy
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`stem from the 1 Jens group to the image plane at the wide-angle end is fw, the fo
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`cal jength of the 1 lens group is fG 1, and the Abbe number of the 1 lensisv i,t
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`he following conditional expressions (1) and (2) are satisfied.
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`{1} 0.05<fw/fG1<0.12
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`(2)v i> 60;
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`[Claim 3]
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`The 2 fens group includes a 2 lens having a negative refractive power on the mos
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`t object side.
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`The 2 lens has an aspherical surface on at least one of an object side and an ima
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`ge plane side.
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`A zoom lens according to claim lor 2.
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`{Claim 4]
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`The 3 fens group has at least one aspherical surface.
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`A zoom lens according to any one of claims 1 te 3.
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`[Claim 5]
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`The 4 lens group is moved to perform focusing.
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`A zoom lens according to any one of claims 1 to 4.
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`{Detailed description of the invention]
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`{Technical field]
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`{O004]
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`The present invention relates to an inner focus type zoom lens which is applied ta
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`a digital still carnera or a digital video camera of high image quality with a solid-s
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`tate imaging device such as a CCD, and more particularly to a zoom lens which h
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`as a wide angie of view and a high zoom ratio.
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`{Background of the Inventian]
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`[0002]
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`A conventional zoom lens mounted on a digital stil camera or the like includes a
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`i iens group, a 2 lens group, a 3 lens group, and a 4 lens group which are arrang
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`ed in this order from an object side so that a lens group having a positive refracti
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`ve power suitable for a high zoorn ratio precedes. A so-called positive lead type z
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`oom jens is known in which at least one aspherical surface is provided in a 3 lens
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`group or a 4 lens group, a 2 liens group is moved, zooming is performed, and a4
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`lens group is moved to perform a variation correction and a focusing accampanyi
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`ng zooming (for example, refer to Patent Document 1}.
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`[0003]
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`Further, as another conventional zoom lens, a 1 lens group, a 2 iens group, anda
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`3 jens group, which are arranged in this arder From the object side, are provided
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`so that a jens group having a negative refractive power suitable for a wide angle
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`of view precedes. A so-called negative lead type zoom jens is known in which a pl
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`urality of aspheric surfaces are provided in a 2 liens group, a 2 jens group is move
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`dso as to move the 2 lens group frorn an image plane side to an abject side and
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`a distance from the 3 lens group is changed, and zooming from the wide-angle en
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`da to the telephoto end is performed (for example, refer to Patent Document 1}.
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`[0004]
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`{Patent docurnent LJIP S 62-L78917A
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`{Patent document Z]IP 2003-L21741A
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`[Risciasure of invention]
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`Problem to be solved by the invention]
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`[O05]
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`However, due to the nature of the zoom jens, in the pasitive lead type zoor lens
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`disclosed in Patent Document 1, the angle of view at the wide-angie end is about
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`50 °, which makes it difficult to achleve a wider angle of view. In addition, in the
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`zoom lens of the negative lead type disclosed in Patent Document 2, the zoom rat
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`io (variable power ratio) which can be secured is about 3 to 4 times as high as po
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`ssible due ta the nature of the zoom lens, and it is difficult to achieve a higher zo
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`om ratio.
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`[O06]
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`In view of the above, ibis an object of the present invention to provide a zoom le
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`ns with high optical performance which achieves both wide angle of view and high
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`zoom ratio, and more particularly, to provide a zoom lens with high optical perfor
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`mance. To provide an inner focus type zoom lens which has a large angle of view
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`at an angie of view of about 75 ° at a wide-angle end, has a large zoom ratio ofa
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`bout 5 times, and has high optical perforrnance in which various aberrations are e
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`xcellently corrected.
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`{Means for solving the problem]
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`[0007]
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`A zoom lens according to the present invention includes a 1 lens group having a 6
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`ositive refractive power, a 2 lens group having a negative refractive power, a 3 le
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`ns group having a positive refractive power, a 4 leans group having a negative refr
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`active power, and a 5 lens group having a positive refractive power in order from
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`the object side toward the image plane side, and the 1 lens group is fixed. Zoomi
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`ng from the wide-angle end to the telephote end is performed by moving the 2 fe
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`ns group from the object side to the image plane side, and aberration correction
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`accompanying zooming is performed by moving the 3 lens group, the 4 lens grou
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`p, and the 5 lens group.
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`According to this configuration, in a state in which the I lens group is stationary,
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`the 2 lens group moves from the object side toward the image plane side, zoomin
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`g from the wide-angle end to the telephoto end is performed, and the 3 lens grou
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`bp, the 4 lens group, and the 5 lens group are appropriately moved, and aberratio
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`n correction accompanying zooming is performed.
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`In this way, an inner focus type zoom lens to which the 1 Jens group is fixed is us
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`ed, and 5 fens groups having positive, negative, positive, negative, and positive r
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`efractive powers are arranged from the object side toward the image plane side.
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`AS a result, a wide angle of view of about 75 ° can be obtained at the wide-angle
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`end, and a zoom jens with high optical performance can be obtained in which a zo
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`om ratio (zoomratio) of about 5 times can be secured and aberrations can be sat
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`isfactorily corrected over the antire zoorn range.
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`[O08]
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`In the above constitution, the 1 lens group consists of a single 1 lens having pasit
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`ive refractive power, and when the focal length of the iens system from the 1 lens
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`group at the wide-angle end ta the image plane is fw, the focal length of the 1 Jen
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`§ group is MG 1 and the Abbe number of the 1 lens is v 1, the following conditional
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`expressions (1}, (2) are obtained.
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`(1) O.05<fw/fG1<0.12
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`{(2Z}v i> 60;
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`It is possible to adopt a configuration satisfying the above condition.
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`According to this configuration, by configuring the 1 lens group having the larger |
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`ens diameter as a single 1 lens group, miniaturization and cost reduction can be a
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`chieved, and by fixing the 1 lens group (1 lens group}, decentering of the lens ca
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`nm be prevented, and the lens can be held firmly, and strength can be increased a
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`gainst an external impact. Further, by satisfying conditional expressions (1) and
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`(2},
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`it is possible to satisfactorily correct various aberrations, especially chrornatic
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`aberrations, while reducing the overall length of the lens system.
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`fOo09]
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`In the above configuration, it is possible to adopt a configuration in which the 2 le
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`ns group includes a 2 lens having a negative refractive power on the most object
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`side, and the 2 lens has an aspherical surface on at least one of the object side a
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`nd the image plane side.
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`According to this configuration, by providing an aspheric surface on the 2 lens loc
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`ated closest to the object side of the 2 lens group, aberrations, especially negativ
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`e distortion, can be corrected well, and a zoom lens with high optical performance
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`can be obtained.
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`fOC19]
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`In the above configuration, the 3 lens group may have at least one aspherical sur
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`Face.
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`According to this configuration, it is possible to satisfactorily correct various aberr
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`ations, particularly, spherical aberration and coma aberration, and to obtain a zoo
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`m lens with high optical performance.
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`fOOLT]
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`In the above configuration, it is possible to adopt a configuration in which the 4 le
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`ns group is moved to perform focusing.
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`According to this configuration, focusing is perforrned by moving the 4 lens group
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`having a relatively small lens diameter and light weight, so that the driving force
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`for focusing can be reduced and the power consumptien consumed by the driving
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`motor can be reduced.
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`{Effect of the Invention]
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`[O12]
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`As described above, according to the zoom lens of the present invention, it is pos
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`sible to obtain a zoom lens with high zoom ratio, wide angle of view, and high opt
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`ical performance in which aberrations are excellently corrected over the entire zo
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`om range. That is, the zoom ratio (variable power ratio) fram which the wide field
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`angle of about 75 degrees is obtained by a wide angle end and which is both aba
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`ut 5 times can be secured, several aberration is corrected satisfactorily, optical pe
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`rformance is hich and a zoom lens suitable for a high-definition digital still camer
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`a, a digital carncorder, etc. is obtained.
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`{Best mode for carrying out the invention]
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`{OCL3]
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`riereinafter, a preferred embodiment of the praesent invention will be described wi
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`th reference to the accompanying drawings.
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`FIGS. 1 and 2 illustrate an embodiment of a zoom lens according to the present |
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`nvention, and FIG. 1 is a basic confiquration diagram, and FIG. 2 is a state diagra
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`m at a wide-angle end, an intermediate position, and a telephoto end.
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`{O014]
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`In this zoom liens, as shown in FIG. 1, a 1 lens group (1) having a positive refracti
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`ve power as a whole is used. A 2 lens group CIT} having negative refracting power
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`as a whole, a 3 lens group CIID having a positive refracting power as a whole, a 4
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`iens group (IV) having a negative refracting power as a whole, and a 5 lens group
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`(V)} having a positive refracting power as a whole are sequentially arranged fram
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`the object side toward the image plane side.
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`Then, as shown in FIGS. 2 (a), (6) and (c}, the 1 lens group (7) is fixed at a pred
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`etermined position. The 2 jens group CIT) moves from the object side toward the |
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`mage plane side, zoorning from the wide-angle end to the telephoto end is perfor
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`med, and the 3 fens group CIT} te the 5 lens group (IV) move from the image pla
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`ne side toward the object side, so that aberration correction accompanying zoomi
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`ng is performed. Further, the 4 lens group (IV) moves to perform focusing (focusi
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`ng operation).
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`In this way, an inner focus type zoom lens to which the 1 lens group (7) is fixed is
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`used, and 5 jeans groups (1), (173, CIT}, CIV}, (V) having positive, negative, positiv
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`e, negative, and positive refractive powers are arranged from the object side tow
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`ard the image plane side. As a result, a wide angle of view of about 75 ° can be o
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`btained at the wide-angle end, and a zoom lens with high optical performance ca
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`nm be obtained in which a zoom ratio (zoom ratio} of about 5 times can be secured
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`and aberrations can be satisfactorily corrected over the entire zoom range.
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`[0015]
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`As shown in FIG. 1, the Liens group C1} includes a single 1 lens L having positive
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`refractive power. As described above, by configuring the 1 lens group of which th
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`e lens diameter is larger than that of the 1 lens group I, it is possible to reduce t
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`he size and cost of the lens, and further, the 1 lens group (the 1 lens 1) is fixed,
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`so that the decentering of the lens can be prevented and the lens can be firmly h
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`eid, and the strength of the lens can be increased.
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`AS shown In FIG. 2, the liens group UID includes a 2 lens 2 having negative refra
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`clive power, a 3 lens 3 having negative refractive power, a 4 lens 4 having negati
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`ve refractive power, and a 5 lens 5 having positive refractive power, which are ar
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`ranged in this order from the object side toward the image plane side.
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`As shown in FIG. 1, the 3 lens group CIT} is arranged in this order fram the objec
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`t side toward the image plane side.
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`This lens comprises a 6 lens 6 naving a positive refractive power, an aperture sto
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`p SD defining a predetermined aperture, a 7 lens 7 having a negative refractive p
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`ower, a 7 lens 7 having a positive refractive power and being bonded to the 8 len
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`s 8, and a 9 lens 9 having a positive refractive power.
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`[0016]
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`As shown in FIG. 1, the 4 lens group CV) includes a 10 lens 10 having positive re
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`fractive power and a li lens 11 having negative refractive power which are arran
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`ged in this order from the object side toward the image plane side and are joined
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`to the 10 lens 10,
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`Incidentally, the 4 lens 10 and the 10 Jens 11 constituting the 11 fens group CIV}
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`have a smaller lens diameter than that of the lens constituting the other lens gro
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`up, and the whole lens group is lighter than the other jens groups. Therefore, wh
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`en focusing is performed by moving the 4 lens group (1V), a driving force for focu
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`sing can be reduced, and hence power consumption consumed by the driving mot
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`or can be reduced,
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`As shown in FiG. 5, the 1 lens group (V} includes a 12 lens 12 having positive ref
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`ractive power and a 13 lens 13 having negative refractive power, which are arran
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`ged in this order from the object side toward the image plane side, and are joined
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`to the 12 fens 12.
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`[O17]
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`Further, in the above configuration, a glass filter 14 serving as an infrared cut fi
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`er, a low-pass filter, or the like is disposed closer to the image plane side than th
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`e 5 lens group (V}, I. e., the 13 lens 13, anc an imaging plane P of the CCD servi
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`nd as a solid-state imaging element is disposed behind the glass filter 14.
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`[0018]
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`Here, the length of the lens systern (from the object-side surface (front surface)
`
`of the I lens 1 to the imaging surface P} is defined as the total length of the jens
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`system. The focal distance of ft, ist lens group (7) - 5th lens group (V} is denoted
`
`for the focal distance of a liens system [ in / for the focal distance of a lens syste
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`m/ in / for the focal distance of a lens system / in / for the focal distance of a len
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`s systern / fand a wide angle end / fw and the mid-position / fm and telephoto e
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`nd ] by fG1-fGs.
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`In addition, inthe 1 lens 1 to the LS lens 13 and the glass filter 14, as shown in F
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`IG. 1, aach surface is represented by Si {I = 1 te 26}, a radius of curvature of eac
`
`h surface Si is represented by Ri (I = 1 to 26), a refractive index for the d-line is
`
`represented by Ni, and a Abbe number is represented by vI (1 = 1 to 14),
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`Furthermore, a distance (thickness, thickness) on each of the optical axes L from
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`the 1 fens 1 to the glass filter 14 to the image plane P. An air gap is represented
`
`by DICE = 1 to 25), a distance from a surface (rear surface} S 24 of the 13 lens i
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`3 on the image plane side to an image plane F is defined as back focus (air conve
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`rsion distance}, and a distance from the rear surface 5 26 of the glass filter 14 to
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`the image plane P is represented by BF.
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`[O19]
`
`The 1 lens i is formed of a glass material and is a meniscus lens having a convex
`
`surface 5 1 on the object side and a concave surface S 2 on the image surface sid
`&.
`
`The 2 lens 2 is formed of a glass material and is a meniscus jens having a convex
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`surface S 3 on the object side and a concave surface S 3 on the image surface sid
`e.
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`The 3 lens 3 is formed of a glass material and is a biconcave lens having a concav
`
`e surface S 5 on the object side and a concave surface S 6 on the image surface ¢
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`ide,
`
`The 4 lens 4 is formed of a glass rnaterial and is a biconcave Jens having a concav
`
`é surface 5 7 on the object side and a concave surface S 8 on the image surface s
`
`ide,
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`The 5 lens 5 is formed of a glass material and is a biconvex liens having a convex
`
`surface S 9 on the object side and a convex surface S 10 on the image surface si
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`de,
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`[0020]
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`The 6 lens 6 is formed of a glass material and is a biconvex iens having a convex
`
`surface 5 Li on the object side and a convex surface S 12 on the irnage surface s
`
`ide,
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`The 7 lens 7 is formed of a glass material and is a biconcave lens having a concav
`
`e surface S 14 on the object side and a concave surface S 15 on the image surfac
`
`e side,
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`The & fens 8 is made of a glass material and is bonded to the 7 lens 7, and is a bi
`
`convex jens having a convex surface S 15 on the object side and a convex surfac
`
`eS 16 on the image surface side.
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`The 9 fens 9 is formed of a glass material, and is a biconvex fens having a convex
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`surface S 17 on the object side and a convex surface 5 18 on the image surface s
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`ide.
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`[0021]
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`The 16 lens 10 is formed of a glass material and is a biconvex lens having a conv
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`ex surface 5 19 on the object side and a convex surface S 20 on the image surfac
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`@ side.
`
`The 11 jens 11 is made of a glass material and is bonded to the 10 fens 10, andi
`
`S a biconcave jens having a concave surface 5S 20 on the object side and a concav
`
`e surface S 21 on the image surface side.
`
`The 12 lens 12 is formed of a glass material and is a biconvex lens having a canv
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`ex surface S 22 on the object side and a convex surface S 23 on the image surfac
`
`e side.
`
`The 13 lens 13 is made of a glass material and is bonded to the 12 lens 12, and i
`
`S$ a meniscus lens having a concave surface 5 23 on the object side and a convex
`
`surface S 24 on the image surface side.
`
`[0022]
`
`In the above configuration, at least one of the object-side surface S 3 and the im
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`age-side surface S 4 of the 2 lens 2 constituting the 2 leans group IT is preferably f
`
`ormed as an aspherical surface, and at least one surface of the object-side surfac
`
`e and the image-side surface of the 6 lens & to the 9 jens 9 constituting the 3 len
`
`§ group IIT is formed as an aspherical surface,
`
`Thus, by providing an aspheric surface on the 2 lens 2 located closest to the obje
`
`ct side of the 2 lens group C11}, aberrations, especially negative distortion, can be
`
`corrected well, and a zoom lens with high optical performance can be obtained. F
`
`urther, by providing an aspheric surface on at least one surface of the lens constit
`
`uting the 3 lens group CIT}, aberrations, particularly spherical aberration and co
`
`ma aberration, can be corrected well, and a zoom lens with high optical performa
`
`nce can be obtained as well.
`
`[0023]
`
`Here, the expression representing an aspheric surface is defined by the following
`
`equation,
`
`Z=Cy2/{i (l-eC 2y 2) 1/2] Dy4+By6+Fy8+Gylo+HyiZ
`
`However, Z : a distance from a tangent plane at an apex of an aspherical surface
`
`to a point on an aspherical surface having a height of y from an optical axis L, y:
`
`a height from an optical axis, C : a curvature at a vertex of an aspheric surface
`
`{1/ RR},
`
`€:
`
`a conic constant, D,, F, G, H : an aspheric surface coefficient.
`
`[O24]
`
`Further, in the above configuration, preferably, the focal length fw of the lens sys
`
`tem from the 1 lens group (1} to the image plane P at the wide-angle end, the foc
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`al length fG 1 of the 1 lens group (, and the Abbe number v 1 of the 1 lens 1 ar
`
`e the following conditional expressions (1) and (2), respectively.
`
`{1} 0.05<fw/fG1<0.12
`
`(2)v i> 60;
`
`It is formed so as to satisfy this condition.
`
`Conditional expression (1) defines the relationship between the focal length of the
`
`leans system at the wide-angle end with respect to the focal length of the 1 lens gr
`
`oup (1) and, when the value of fw / fG 1 exceeds the lower limit value, the total |
`
`ength of the lens system becomes longer, whereas when the value of fw /fG 1 ex
`
`ceeds the upper limit value, correction of chromatic aberration becomes difficult.
`
`Accordingly, by satisfying Conditional Expression (1), it is possible to reduce the o
`
`verall jenath of the lens system, thereby achieving miniaturization, and it is possi
`
`ble to favorably correct aberrations, particularily chromatic aberrations, over the e
`
`ntire range of the variable power range.
`
`Conditional expression (2) defines the Abbe number of the 1 lens 1, and by satisf
`
`ying this conditional expression (2), aberrations, particularly chromatic aberration
`
`s, can be excellently corrected over the entire range of the variable power range.
`
`[0025]
`
`Examples of specific numerical values of the zoom Jens having the above configur
`
`ation will be described below as Embodiment 1. In Embodiment 1, the object-side
`
`surface 5 3 of the 2 lens 2, the object-side surface S 11 of the 6 jens 6, and thes
`
`urface S 12 of the image plane side are each forrned into an aspheric surface, an
`
`d the other surfaces are formed into spherical surfaces.
`
`jExample 1]
`
`[0026]
`
`Table 1 shows main specification specifications of Example 1, and Table 2 shows
`
`various numerical data (setting values}. Numerical data relating to the aspherical
`
`surface is shown in Table 3, and numerical data concerning the focal length (wide
`
`angle end fw, intermediate position fm, and telephoto end ft) of the lens system
`
`at the wide-angle end, the intermeciate position, the telephoto end, and the dista
`
`nce (interval) D2,010,D18,D21,024 on the optical axis L are shown in Table 4.
`
`Further, numerical data of conditional expressions (1) and (2) are obtained.
`
`(1) fw/fGi=7.25/87.438=0.083,
`
`(2)vi = 70.2.
`
`[0027]
`
`Further, aberration diagrams relating to spherical aberration, astigmatism, and di
`
`Stortion aberration at the wide-angle end, the intermediate position, and the tele
`
`photo end have results as shown in FIGS. 3 4, and 5. In FIGS. 3 to 5, d represent
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`S an aberration caused by a d-line, F represents an aberration caused by an F lin
`
`e, 5 represents an aberration on a sagittal plane, and M represents an aberration
`
`on a meridional plane.
`
`[0028]
`
`{Table 1]
`
`SREARE Gm)
`
`#6 SIERE (mm)
`
`KoDARE
`
`peso OW) | MINER QM) whee (Tb)
`
`NCP LABECSSRST
`
`SOGm}
`
`we C20) ©
`
`|
`
`vi ABS Cnm)
`CSS Lb ROO~ NO ET
`ORO
`Re FF e—-HR loam)
`(BL Bee RL SOR~ MR
`
`(0029)
`
`[Table 2]
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`Page 15 of 48
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`HIPS Cd a)
`
`RB oo GREH)
`
`R7Y~iGS. 558
`
`RSee591R926.735).|owetog
`3. 800Phpio
`
`26. 7sa 5
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`NiO
`80518
`
`Nil
`
`(0030)
`
`[Table 3]
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`Page 17 of 48
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`SERRE
`
`4. taaxaor
`
`6. 259K 707%
`
`Pog|
`
`{O031]
`
`[Table 4]
`
` D2 Gam)
`
`Re OW)
`
`
`
`RAC OM)
`
`
`
`goa CT)
`
`
`
`
`
`
`27.
`40, 807
`Dio (mm)
`
`
`
`z1. O81
`DiB8 (mm)
`1. 00
`5
`Te:
`
`9. 349
`Dei (mm)
`4. 383
`‘
`
`
`
`13. 987
`p24 Gnm)
`8. 2868
`
`
`
`1. 400
`
`Ll. 919
`
`22. 498
`
`2. 008
`
`3
`5. 058
`
`[O032]
`
`In Embodiment 1 described above, the total length of the lens system at each of t
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`he wide-angle to the intermediate to telephoto positions is set as follows :
`
`In the front face Si - the image forrnation face P of the one lens 1, 105.4 mm (fix
`
`ed) and a back focus (air scated distance from the rear face S24 of the 13th lens
`
`i3 to the image formation face P) 7.02mm-8.25mm-15.94mm,
`
`In a variable pow
`
`er ratio (zoom magnifying power}, 4.86 (constant value} and the f nurnber 2.90
`
`-3,28-5.15 and a fleld angle (2Zomega) will be 77.3 dagrees ~ 51.4 degrees - 17.5
`
`dearees, and the zoom lens with high optical performance with which several abe
`
`rration was satisfactorily corrected by the wide field angle and the high zooming r
`
`atic is obtained.
`
`[0033]
`
`FIGS. & and 7 show another embodiment of the zoom lens according to the prese
`
`nt invention, and FIG. 6 is a basic configuration diagram, and FIG. 7 is a state dia
`
`gram at a wide-angle end, an intermediate position, and a telephoto end. In this
`
`embodiment, it is basically the same as the above-described embodiment except
`
`that the number of lenses constituting the 2 lens group {IT} is increased by one, a
`
`nd a description thereof will be omitted.
`
`[0034]
`
`In this ernbodiment, as shown in FIG. &, the 2 lens group (11) includes a 2 lens 2
`
`having negative refractive power and a 3 lens 3 having positive refractive power,
`
`which are arranged in this order from the object side toward the image plane sid
`
`@. It is constituted by a 3 lens 3° which is jained to the 4 lens 4° and has negativ
`
`e refractive power, a 5 lens 5 ' which has negative refractive power, and a 6 lens
`
`6 ‘ which has positive refractive power.
`
`As shown in Fic. 6, the 3 liens group CIT) is arranged in this order from the objec
`
`t side toward the image plane side. This leans is composed of a 7 lens 7 having po
`
`sitive refractive power, an aperture stop SD defining a predetermined aperture, a
`
`8 jens &' having negative refractive power, a 8 lens &' joined to the 9 lens 9 and
`
`having positive refractive power, and a 10 lens 10' having positive refractive pow
`er.
`
`As shown in FIG. 6, the 4 lens group (1V} includes a Li lens 11° having positive r
`
`efractive power and a 12 jens 12° having negative refractive power, which are ar
`
`ranged in this order from the object side toward the image plane side, and are joi
`
`ned ta the Lijens 11/,
`
`As shown in FIG. 6, the 5 lens group (V) includes a 13 lens 13’ having positive re
`
`fractive power and a 14 lens 14° having negative refractive power, which are arr
`
`anged in this order from the object side toward the image plane side, and are join
`
`ed tothe is lens i3/.
`
`{0035}
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`Page 19 of 48
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`Further, in the above configuration, a glass filter 15 serving as an infrared cut FIL
`
`er, a low-pass filter, or the like is disposed closer to the image plane side than th
`
`e 5 lens group (V}, f. a, the 14 lens 14°, and an image plane P of the CCD as as
`
`olid-state image pickup element is disposed behind the glass filter 15.
`
`[0036]
`
`Here, in the i lens 1 to the 14 lens 14’ and the glass filter 15, as shown in FIG.
`
`6, each surface is represented by Si {I = 1 to 27}, a radius of curvature of each s
`
`urface Si is represented by Ri (I = 1 to 27), a refractive index for the d-line is rep
`
`resented by Ni, and a Abbe number is represented by v I (Il = i to 15).
`
`Furthermore, a distance (thickness, thickness) on each of the optical axes L from
`
`the 1 lens 1 to the glass filter 15 to the image plane P. An air gap is represented
`
`by Di(T = 1 to 26), a distance from the surface (rear surface} S 25 of the 14 lens
`
`14’ on the image plane side to an image plane P is defined as back focus (air edu
`
`ivalent distance}, and a distance frorn the rear surface 5 27 of the glass filter 15 t
`
`o the image plane P is represented by BF.
`
`[0037]
`
`The 3 lens 3’ is formed of a glass material and is a meniscus lens having a conca
`
`ve surface S 5 on the object side and a convex surface S 6 on the image surface
`
`side.
`
`The 4 fens 4° is made of a glass material and is bonded to the 3 lens 3’, andisa
`
`biconcave lens having a concave surface 5 6 on the object side and a concave sur
`
`face 5 7 on the imaqe surface side.
`
`The 5 fens 5‘ is formed of a glass material and is a biconcave leans having a conc
`
`ave surface S & on the object side and a concave surface S 9 on the image surfac
`
`@ side,
`
`The 6 lens 6‘ is formed of a glass material and is a biconvex lens having a conve
`
`x surface S 10 on the object side and a convex surface S 11 on the image surface
`
`side.
`
`[0038]
`
`The 7 lens 7 ’ is formed of a glass material and is a biconvex lens having a conve
`
`x surface S 12 on the object side and a convex surface S 13 on the image surface
`
`side.
`
`The & lens 8 / is formed of a glass material and is a biconcave lens having a conc
`
`ave surface S 15 on an object side and a concave surface S 16 on an image surfa
`
`ce side.
`
`The 9 fens 9’ is formed of a glass material and is banded to the 8 lens & ‘, and is
`
`@ biconvex lens having a convex su