JP2006065034A - Zoom lens and imaging apparatus having the same - Google Patents

Zoom lens and imaging apparatus having the same Download PDF

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JP2006065034A
JP2006065034A JP2004248229A JP2004248229A JP2006065034A JP 2006065034 A JP2006065034 A JP 2006065034A JP 2004248229 A JP2004248229 A JP 2004248229A JP 2004248229 A JP2004248229 A JP 2004248229A JP 2006065034 A JP2006065034 A JP 2006065034A
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lens
lens group
positive
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zoom
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JP4666977B2 (en )
JP2006065034A5 (en )
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Makoto Sekida
誠 関田
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Canon Inc
キヤノン株式会社
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Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens which gets along with a small number of constituent lenses and is compact while maintaining the zoom ratio of three times or more and the excellent optical performance.
SOLUTION: The zoom lens has a first lens group having negative refractive power, a second lens group having positive refractive power and a third lens group having positive refractive power in order from the object side to the image side, wherein spaces between respective groups are changed upon zooming. The first lens group L1 is composed of one sheet of negative lens and one sheet of positive lens, the second lens group L2 is composed of a 2a lens group L2a having one sheet of positive lens/one sheet of negative lens and a 2b lens group L2b which is arranged on the image side of the 2a lens group and has at least one sheet of positive lens, and the third lens group is composed of at least one sheet of positive lens.
COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明はズームレンズに関し、特に小型のデジタルスチルカメラやビデオカメラの撮影光学系として好適なものである。 The present invention relates to a zoom lens, and particularly suitable as a photographic optical system of a small digital still camera and a video camera.

最近、CCDやCMOSセンサ等の固体撮像素子(光電変換素子)を用いたビデオカメラ、デジタルスチルカメラ等の撮像装置(カメラ)の高機能化にともない、それに用いる光学系には広い画角を包含した大口径比のズームレンズが求められている。 Recently, with the sophistication of the solid-state image sensor such as a CCD or CMOS sensor (photoelectric conversion element) video camera using an imaging device such as a digital still camera (Camera), encompasses a wide field angle to the optical system used therefor zoom lens of a large aperture ratio has been demanded that.

この種のカメラには、撮影光学系のレンズ最後部と撮像素子との間に、ローパスフィルターや色補正フィルターなどの各種光学部材を配置する必要があるため、比較的バックフォーカスの長いレンズ系が要求される。 This type of camera, between the lens rearmost portion and an image pickup element of the imaging optical system, it is necessary to place the various optical members such as a low-pass filter and a color correction filter, the long lens system having a relatively back focus is required. さらに、カラー画像用の撮像素子を用いたカラーカメラの場合、色シェーディングを避けるため、それに用いる光学系には像側のテレセントリック特性の良いものが望まれている。 Furthermore, in the case of a color camera using an image sensor for color images, in order to avoid color shading, it is desired good telecentricity on the image side in the optical system used therein.

従来、負の屈折力の第1レンズ群と正の屈折力の第2レンズ群との2つのレンズ群より成り、双方のレンズ間隔を変えて変倍を行う、所謂ショートズームタイプの広画角の2群ズームレンズが種々提案されている。 Conventionally, it consists of two lens groups and the second lens unit having a negative refractive power first lens group and positive refractive power, and performs zooming by changing both the lens distance, wide angle of so-called short zoom type 2-group zoom lens has been proposed in. これらのショートズームタイプの光学系では、正の屈折力の第2レンズ群を移動することで変倍を行い、負の屈折力の第1レンズ群を移動することで変倍に伴う像位置の変動の補償を行っている。 These short zoom type of optical system performs zooming by moving the second lens unit having a positive refractive power, the image position due to zooming by moving the first lens unit having a negative refractive power It is doing the compensation of the change. これらの2つのレンズ群より成るレンズ構成においては、ズーム倍率(ズーム比)は2倍程度である。 In the lens construction composed of these two lens units, the zoom magnification (zoom ratio) is about 2 times.

さらに2倍以上の高いズーム比を有しつつ、レンズ全体をコンパクトな形状にまとめるため、2群ズームレンズの像側に負または正の屈折力の第3レンズ群を配置し、高ズーム比化に伴って発生する諸収差の補正を行う、所謂3群ズームレンズが提案されている(特許文献1,2)。 While further has twice or more higher zoom ratio, to put together the entire lens into a compact shape, arranged third lens unit having a negative or positive refractive power on the image side of the two-unit zoom lens, a high zoom ratio correct various aberrations generated due to the so-called three-unit zoom lens has been proposed (Patent documents 1 and 2).

また、3群ズームレンズとしてバックフォーカスとテレセントリック特性を満足する広画角の3群ズームレンズ系も知られている(特許文献3,4)。 Also, three-unit zoom lens system of the wide-angle to satisfy the back focus and telecentric properties as a three-group zoom lens has been known (Patent Documents 3 and 4).

また、3群ズームレンズのコンパクト化のために、第1レンズ群を負・正の2枚のレンズ構成とし、第2レンズ群に接合レンズを効果的に配置した3群ズームレンズも知られている(特許文献5〜8)。 Moreover, because of the compactness of the zoom lens, the first lens group is a negative-positive two lenses constituting the cemented lens effect arranged with the three-group zoom lens also known in the second lens group It is (Patent documents 5-8).

また、3倍以上の高いズーム比を有する3群ズームレンズも知られている(例えば特許文献9,10)。 It is also known zoom lens having more than three times higher zoom ratio (for example, Patent Documents 9 and 10).

また、3倍以上の高いズーム比を有しながら、比較的少ないレンズ枚数にて構成した3群ズームレンズも知られている(特許文献11〜13)。 Further, while having a more than three times higher zoom ratio, also known zoom lens constituted by a relatively small number of lenses (Patent Document 11 to 13).
特公平7−3507号公報 Kokoku 7-3507 Patent Publication No. 特公平6−40170号公報 Kokoku 6-40170 Patent Publication No. 特開昭63−135913号公報 JP-A-63-135913 JP 特開平7−261083号公報 JP-7-261083 discloses 特開2002−196240号公報 JP 2002-196240 JP 特開2002−350726号公報 JP 2002-350726 JP 特開2003−222797号公報 JP 2003-222797 JP 特願2004−148893号公報 Japanese Patent Application No. 2004-148893 Patent Publication No. 米国特許第4828372号明細書 US Pat. No. 4828372 特開平4−217219号公報 JP-4-217219 discloses 特開平10−213745号公報 JP 10-213745 discloses 特開2002−277740号公報 JP 2002-277740 JP 特開2003−21783号公報 JP 2003-21783 JP

35mmフィルム写真用に設計されている上記した3群ズームレンズは、固体撮像素子を用いるカメラには、バックフォーカスが長すぎ、又テレセントリック特性が良くないため、固体撮像素子を用いるビデオカメラやデジタルスチルカメラにそのまま用いることが難しい。 Zoom lens described above is designed 35mm film for photograph, a camera using a solid-state imaging device, since the back focus is too long, also poor telecentricity, video cameras and digital still using a solid state imaging device as it is difficult to be used in the camera.

一方、近年カメラのコンパクト化とズームレンズの高ズーム比化を両立するために、非撮影時(カメラの電源オフ時)に各レンズ群の間隔を撮影状態と異なる間隔まで縮小し、カメラ本体からのレンズの突出量を少なくした所謂沈胴式のズームレンズが広く用いられている。 Meanwhile, in order to achieve both a high zoom ratio of compact zoom lens recent camera, reduced to non-shooting time differs from the interval photographing state of the lens groups (when the camera is powered off) intervals, from the camera body so-called retractable zoom lens protruding amount was less lenses have been widely used.

一般に、ズームレンズを構成する各レンズ群のレンズ枚数が多いと、各レンズ群の光軸上の長さが長くなり、又、各レンズ群のズーミング及びフォーカシングにおける移動量が大きいとレンズ全長が長くなり、所望の沈胴長が達成できなくなり、沈胴式のズームレンズに用いるのが難しくなる。 In general, the number of lenses in each lens unit constituting the zoom lens is large, becomes the length on the optical axis is long between the lens groups, also the total lens length is long is greater amount of movement during zooming and focusing of the lens groups becomes, the desired collapsed length no longer be achieved, to use the retractable zoom lens becomes difficult.

本発明は、上述した従来例を鑑みなされたもので、所望のズーム比、所望の光学性能を維持しつつ、構成レンズ枚数が少なく、コンパクトで新規なズームレンズの提供を目的とする。 The present invention has been made in view of the prior art example described above, a desired zoom ratio, while maintaining a desired optical performance, number of lenses is small, and an object thereof is to provide a novel zoom lens compact.

本発明のズームレンズは、物体側より像側へ順に、負の屈折力の第1レンズ群、正の屈折力の第2レンズ群、正の屈折力の第3レンズ群を有し、ズーミングに際し各群の間隔が変化するズームレンズにおいて、第1レンズ群を、1枚の負レンズと1枚の正レンズで構成し、第2レンズ群を、1枚の正レンズと1枚の負レンズから成る第2aレンズ群と、第2aレンズ群の像側に配置され、少なくとも1枚の正レンズを有する第2bレンズ群で構成し、第3レンズ群は、少なくとも1枚の正レンズで構成している。 The zoom lens of the present invention includes, in order from the object side to the image side, a first lens unit having a negative refractive power, a second lens unit having positive refractive power, a third lens unit having positive refractive power, zooming in the zoom lens intervals of each group is changed, the first lens group is constituted with one negative lens and one positive lens, the second lens group, one positive lens and one negative lens a first 2a lens group composed, is disposed on the image side of the 2a lens group is constituted by the 2b lens group having at least one positive lens, the third lens group is constituted by at least one positive lens there. そして、第2レンズ群の広角端での結像倍率をβ2w、望遠端での結像倍率をβ2t、第1レンズ群と第2レンズ群の広角端での間隔をL1w、第2レンズ群と第3レンズ群の望遠端での間隔L2tとするとき、 Then, the imaging magnification at the wide angle end of the second lens group .beta.2w,? 2t imaging magnification at the telephoto end, the spacing in the first lens group wide-angle end of the second lens group L1W, a second lens group when the interval L2t at the telephoto end of the third lens group,
4.5<(β2t・L2t)/(β2w・L1w)<10.0 4.5 <(β2t · L2t) / (β2w · L1w) <10.0
なる条件を満足することを特徴としている。 It is characterized by satisfying the following condition.

このような構成により、所望のズーム比(例えば3倍以上)、所望の光学性能を維持しつつ、構成レンズ枚数が少なく、コンパクトなズームレンズが実現できる。 With this configuration, a desired zoom ratio (e.g. 3 times), while maintaining a desired optical performance, small number of lenses, compact zoom lens can be realized.

以下に図面を用いて本発明のズームレンズの実施例について説明する。 Below examples of the zoom lens of the present invention will be described with reference to the drawings. 本実施形態のズームレンズは、ビデオカメラやデジタルスチルカメラ等の撮影光学系として用いられるものである。 The zoom lens of the present embodiment is used as an imaging optical system such as a video camera or a digital still camera.

図1,3,5は、それぞれ実施例1〜3のズームレンズのレンズ断面図である。 Figure 1, 3 and 5, a lens cross-sectional view of each of Examples 1-3 the zoom lens. 図2,4,6は、それぞれ実施例1〜3のズームレンズの収差図であり、(a)が広角端の状態、(b)が中間のズーム位置の状態、(c)が望遠端の状態である。 Figure 2, 4, 6 are aberration diagrams of each of Examples 1 to 3 zoom lens, (a) is a wide-angle end state, (b) the state of the middle zoom position, the telephoto end (c) it is a state.

各レンズ断面図において、左方が被写体側(前方)で、右方が像側(後方)である。 In each lens sectional view, the left is the object side (front) and the right side is the image side (rear). L1は負の屈折力(光学的パワー=焦点距離の逆数)の第1レンズ群、L2は正の屈折力の第2レンズ群、L3は正の屈折力の第3レンズ群である。 L1 denotes a first lens unit having a negative refractive power (optical power = reciprocal of focal length), L2 denotes a second lens unit having positive refractive power, L3 denotes a third lens unit having a positive refractive power. L2aは第2レンズ群L2中の物体側に配置された第2aレンズ群であり、1枚の正レンズと1枚の負レンズで構成されている。 L2a is composed of the 2a lens is group, one positive lens and one negative lens disposed on the object side in the L2 second lens group. L2bは第2aレンズ群L2aの像側に配置された少なくとも1枚の正レンズを有する第2bレンズ群である。 L2b is the 2b lens group having at least one positive lens arranged on the image side of the 2a lens group L2a. SPは開口絞り(Fナンバー決定部材)、Gは光学的ローパスフィルター、赤外カットフィルター、カバーガラス等の光路中に存在する平行平板に対応して設計上設けたガラスブロック、IPはCCDセンサやCMOSセンサ等の固体撮像素子(光電変換素子)の感光面が位置する像面である。 SP is the aperture stop (F-number determining member), G is an optical low-pass filter, an infrared cut filter, a glass block provided on the correspondingly designed parallel plates present in the optical path, such as a cover glass, IP is Ya CCD sensor photosensitive surface of the solid-state imaging device such as a CMOS sensor (photoelectric conversion element) is an image plane located. 開口絞りSPは開放時の軸上のFナンバー光線を決定する部材である。 The aperture stop SP is a member for determining F-number light on axis upon opening.

各収差図において、d,gは各々d線及びg線、ΔM、ΔSはメリジオナル像面、サジタル像面、倍率色収差はg線によって表している。 In respective graphs, d, g d-line and the g-line, .DELTA.M, [Delta] S is a meridional image plane and a sagittal image plane, the magnification chromatic aberration is represented by the g-line.

本実施形態のズームレンズでは、物体側より像側へ順に、第1レンズ群L1、第2レンズ群L2、第3レンズ群L3が配置されている。 In the zoom lens of the present embodiment includes, in order from the object side to the image side, a first lens unit L1, the second lens unit L2, the third lens unit L3 is disposed. 広角端から望遠端へのズーミングに際しては、第1レンズ群L1が像側に凸の軌跡でほぼ往復移動、第2レンズ群L2が物体側に移動、第3レンズ群L3が像側に移動することにより、各レンズ群の間隔を変えている。 During zooming from the wide-angle end to the telephoto end, the first lens unit L1 substantially reciprocally moves in a convex locus toward the image side, moves the second lens unit L2 toward the object side, the third lens unit L3 moves toward the image side by, and changing the spacing between the lens units.

本実施形態のズームレンズは、ズーミングに際し、第2レンズ群L2の移動により主な変倍を行い、第1レンズ群L1の往復移動及び第3レンズ群L3による像側方向への移動によって変倍に伴う像位置の変動を補償している。 The zoom lens of this embodiment, during zooming, mainly performs zooming by moving the second lens unit L2, magnification by the movement of the image side direction of the reciprocating movement and the third lens unit L3 in the first lens unit L1 to compensate for a variation of the image position due to.

本実施形態では、Fナンバー決定部材としての開口絞りSPを第2レンズ群L2の物体側に配置し、広角側での入射瞳と第1レンズ群L1との距離を縮めることで、第1レンズ群L1を構成するレンズの外径の増大を抑えると共に、開口絞りSPを挟んで第1レンズ群L1と第3レンズ群L3とで軸外の諸収差を打ち消させることで、構成レンズ枚数を増やさずに良好な光学性能を得ている。 In the present embodiment, the aperture stop SP as F-number determining member disposed on the object side of the second lens unit L2, by reducing the distance between the entrance pupil and the first lens unit L1 at the wide-angle side, the first lens while suppressing an increase in the outer diameter of the lenses constituting the group L1, a first lens unit L1 across the aperture stop SP by causing canceled aberrations in off-axis between the third lens unit L3, increasing the number of lenses It has excellent optical performance without.

なお、図1,3,5に示すレンズ断面図から明らかなように、開口絞りSPは、光軸方向の座標で、第2レンズ群L2の最も物体側に配置されたレンズの物体側のレンズ面の頂点と、このレンズ面とレンズ端面(所謂コバ面)との交点の間に配置されている。 As is apparent from the lens cross-sectional view shown in FIG. 1, 3, 5, the aperture stop SP, in the optical axis direction coordinate, the object side of the lens of a lens disposed on the most object side of the second lens unit L2 and vertices of the surface, is disposed between the intersection of the lens surface and the lens end face (so-called edge surface). 開口絞りSPをこのように第2レンズ群L2の最も物体側に配置されたレンズの物体側頂点よりも像側に配置することで、レンズ沈胴長の短縮化を図っている。 The aperture stop SP than the object-side vertex of the thus lens arranged closest to the object side in the second lens group L2 by arranging the image side, thereby shortening of the lens retracted length.

このような開口絞りSPの配置により、レンズ沈胴長の短縮化が図れる理由について説明する。 By this arrangement of the aperture stop SP, it will be described why the lens retracted length shortening of can be achieved.

従来のショートズームタイプの3群ズームレンズにおいては、第1レンズ群と第2レンズ群の間に開放Fナンバーを決定するための絞り部材を配置することが一般的である。 In the three-unit zoom lens of a conventional short zoom type, placing the stop member for determining the open F-number between the first and second lens groups are common. また、一般的にショートズームタイプの第1レンズ群の最も像側には、像側に凹面を向けたメニスカス正レンズが配置されている。 Further, the most image side of the first lens group commonly short zoom type, positive meniscus lens having a concave surface facing the image side is disposed.

レンズ沈胴時に第1レンズ群と第2レンズ群の間隔を撮影状態よりも縮小しようとした場合、第1レンズ群の最も像側のメニスカス正レンズは、像側に凹面を向けている関係で、このメニスカス正レンズのレンズ外周部と絞り部材が干渉してしまい、メニスカス正レンズの像側頂点からレンズ外周部までの間隔分はレンズ沈胴長を短くすることができない。 If you try to shrink than the distance the shooting state of the first lens group and the second lens group when the lens retracted, positive meniscus lens on the most image side in the first lens group is a relationship that a concave surface facing the image side, the meniscus would be a positive lens lens outer peripheral portion and the diaphragm member interferes spacing component from the image side apex of the positive meniscus lens to the lens outer peripheral portion can not be shortened lens retracted length.

また、絞り部材と第2レンズ群の最も物体側に配置されたレンズの物体側頂点との間隔も、絞り部材を第1レンズ群と第2レンズ群の間に配置する場合は、ある程度の間隔を確保しなければならず、これもレンズ沈胴長を短くすることができない要因の一つである。 The diaphragm member and the interval between the object-side vertex of the lens disposed on the most object side of the second lens group, when arranging the diaphragm member between the first lens group and the second lens group, some distance It must be ensured, which is also one of the factors that can shorten the lens retracted length.

本実施形態においては、絞り部材としてのFナンバー決定部材(開口絞りSP)を、上述したように第2レンズ群L2の最も物体側に配置されたレンズの物体側頂点と、このレンズの物体側の面とレンズ端面との交点の間に配置することで、沈胴時に機械的に干渉が生じる部材を第1レンズ群L1と第2レンズ群L2の間からなくし、レンズ沈胴時に第1レンズ群L1と第2レンズ群L2との間隔を極限まで近づけることを可能としている。 In the present embodiment, the F-number determining member as a throttle member (aperture stop SP), the object-side vertex of the lens disposed on the most object side of the second lens group L2 as described above, the object side of the lens It is located between the intersection of the surface and the lens end face, eliminating a member mechanically interfere during retraction occurs from between the first lens unit L1 and the second lens unit L2, the first lens group when the lens retracted L1 When is the distance between the second lens unit L2 and allows close to the limit.

次に各レンズ群の構成についてより詳しく説明する。 It will be described in more detail the configuration of each lens unit.

第1レンズ群L1は、物体側から順に、物体側に凸面を向けたメニスカス負レンズ、物体側に凸面を向けたメニスカス正レンズの2枚のレンズで構成している。 The first lens unit L1 includes, in order from the object side, a meniscus negative lens having a convex surface directed toward the object side, is constituted by two lenses of positive meniscus lens having a convex surface directed toward the object side.

第1レンズ群L1は、軸外主光線を絞り中心に瞳結像させる役割を持っており、特に広角側においては軸外主光線の屈折量が大きいために軸外諸収差、特に非点収差と歪曲収差が発生し易い。 The first lens unit L1, has a role of pupil imaging centered aperture off-axis principal ray, off-axis aberrations for refraction of the off-axis principal ray is large, particularly in the wide-angle side, particularly astigmatism and distortion aberration is likely to occur.

そこで本実施形態では、通常の広角レンズと同様、最も物体側のレンズ径の増大が抑えられる負レンズと正レンズの構成としている。 In this embodiment, similarly to the ordinary wide-angle lens has a configuration of a negative lens and a positive lens that increases the lens diameter on the most object side is suppressed.

そして、メニスカス負レンズの物体側のレンズ面を周辺で正の屈折力が強くなる非球面とし、像側のレンズ面を周辺で負の屈折力が弱くなる非球面とすることにより、非点収差と歪曲収差をバランス良く補正すると共に、2枚と言う少ない枚数で第1レンズ群L1を構成し、レンズ全体のコンパクト化に寄与している。 By the aspherical surface positive refractive power becomes stronger the lens surface on the object side of the negative meniscus lens at the periphery, the negative refractive power in the near the lens surface on the image side is an aspheric surface that is weakened, astigmatism distortion as well as well-balanced correction for, a small number say two constitute the first lens unit L1, which contributes to downsizing of the entire lens with.

また第1レンズ群L1を構成する各レンズは、軸外主光線の屈折によって生じる軸外収差の発生を抑えるために、開口絞りSPと光軸が交差する点を中心とする同心球面に近い形状をとっている。 The respective lenses constituting the first lens unit L1, in order to suppress the occurrence of off-axis aberration caused by refraction of off-axis principal ray, close to concentric spherical aperture stop SP and the optical axis is centered on the point of intersection shape It is taking.

第2レンズ群L2は、物体側から順に、物体側に凸面を向けた正レンズと像側に凹面を向けた負レンズとの接合レンズで構成された第2aレンズ群L2aと、物体側に凸面を向けたメニスカス負レンズと両面が凸形状の正レンズとの接合レンズで構成された、あるいは両面が凸形状の正レンズで構成された第2bレンズ群L2bの合計4枚又は3枚レンズで構成されている。 The second lens unit L2 includes, in order from the object side, a first 2a lens group L2a that is a cemented lens of a negative lens having a concave surface facing the positive lens and the image side with the convex surface facing the object side, a convex surface on the object side constituted by a meniscus negative lens with both surfaces are composed of a cemented lens of a positive lens convex, or the 2b lens group total of four or three lenses L2b both sides is composed of a positive lens element convex shape with its It is.

第2レンズ群L2は、最も物体側に正レンズを配置し、第1レンズ群L1を射出した軸外主光線の屈折角を少なくし、軸外諸収差が発生しないような形状としている。 The second lens unit L2, placing a positive lens closest to the object side, a first lens unit L1 to reduce the angle of refraction of the off-axis principal ray emitted, are shaped so as to off-axis aberrations does not occur.

また、最も物体側に配置された正レンズは、最も軸上光線の通る高さが高いレンズであり、主に球面収差、コマ収差の補正に関与しているレンズである。 Further, the positive lens disposed closest to the object side, the most high through the axial ray is high lenses, mainly spherical aberration, lenses involved in correction of coma. そこで本実施形態においては、最も物体側に配置された正レンズの物体側の面を周辺で正の屈折力が弱くなる非球面とすることにより球面収差、コマ収差を良好に補正している。 Accordingly, in the present embodiment, is well corrected spherical aberration, coma aberration by the aspherical surface positive refractive power of the object-side surface of the positive lens disposed closest to the object side in a peripheral is weakened.

また、最も物体側に配置された正レンズの像側に配置した負レンズの像側の面形状を、像側に凹面を向けた形状とすることで、最も物体側に配置された正レンズの物体側の面で発生した収差をキャンセルさせている。 Furthermore, most objects the image side of the negative lens disposed on the image side of the deployed positive lens side surface shape by a shape with a concave surface facing the image side, a positive lens disposed on the most object side and to cancel the aberration generated in the surface on the object side.

更に、最も物体側に配置された正レンズと、その正レンズの像側に配置した負レンズは、レンズが光軸に対して偏心することによって生じる像面の倒れの敏感度が、ほぼ同等量でかつ異符号であるという点に着目し、この正レンズと負レンズを接合することで、接合レンズ全体として像面の倒れをキャンセルさせ、製造誤差に対して性能劣化が少ないレンズ構成としている。 Furthermore, a positive lens disposed on the most object side, the negative lens disposed on the image side of the positive lens, the image plane sensitivity of inclination of which caused by the lens is decentered relative to the optical axis is approximately equivalent amounts in and paying attention to the point that it is opposite sign, this by joining a positive lens and a negative lens, to cancel the inclination of the image plane as a whole a cemented lens, and the performance degradation is small lenses configured for manufacturing error.

第3レンズ群L3は、両レンズ面が凸形状の正レンズ1枚で構成している。 The third lens unit L3, both lens surfaces is constituted by one positive lens element convex shape.

第3レンズ群L3は、撮像素子の小型化に伴うズームレンズを構成する各レンズ群の屈折力の増大を分担し、第1、第2レンズ群L1,L2で構成されるショートズーム系の屈折力を減らすことで、特に第1レンズ群を構成するレンズでの収差の発生を抑え良好な光学性能を達成している。 The third lens unit L3, shares the increase of the refractive power of each lens unit constituting the zoom lens due to the size of the imaging device, first, refracting short zoom system constituted by the second lens group L1, L2 by reducing the force, and achieve good optical performance suppressing particular aberrations in lenses constituting the first lens group. また、特に固体撮像素子等を用いた撮影装置に必要な像側テレセントリックな結像を第3レンズ群L3にフィールドレンズの役割を持たせることで達成している。 Also it has been achieved by particularly to have a role of imaging device field lens an image-side telecentric imaging required third lens unit L3 in using a solid state imaging device or the like.

ここで、バックフォーカスをsk′、第3レンズ群L3の焦点距離をf3、第3レンズ群L3の結像倍率をβ3とすると、 Here, sk back focus', the focal length of the third lens unit L3 f3, if the imaging magnification of the third lens unit L3 and .beta.3,
sk′=f3(1−β3) sk '= f3 (1-β3)
の関係が成り立っている。 It is made up of the relationship.

但し、 However,
0<β3<1.0 0 <β3 <1.0
である。 It is.

ここで、広角端から望遠端へのズーミングに際して、第3レンズ群L3を像側に移動させると、バックフォーカスsk′が減少することになり、第3レンズ群L3の結像倍率β3が望遠側で増大することになる。 Here, during zooming from the wide-angle end to the telephoto end, by moving the third lens unit L3 on the image side, it will be reduced back focus sk ', the imaging magnification β3 of the third lens unit L3 telephoto side in will increase. すると、結果的に第3レンズ群L3で変倍を分担することになり、第2レンズ群L2の移動量が減少し、そのためのスペースが節約できるためにレンズ系の小型化に寄与する。 Then, eventually it will be shared zooming by the third lens unit L3, the moving amount of the second lens unit L2 is reduced, which contributes to the miniaturization of the lens system in order to save space therefor.

本実施形態のズームレンズを用いて近距離物体を撮影する場合には、第1レンズ群L1を物体側へ移動させてフォーカスを行うことで良好な性能を得ることもできるが、さらに望ましくは、第3レンズ群L3を物体側に移動させてフォーカスを行った方が良い。 When photographing a close object using the zoom lens of the present embodiment, the first lens unit L1 can be obtained good performance by performing focusing by moving toward the object side, and more preferably, it is better to perform focusing by moving the third lens unit L3 to the object side.

これは、最も物体側に配置した第1レンズ群L1をフォーカシングで移動させた場合に生じる、前玉径の増大や、レンズ重量が最も重い第1レンズ群L1を移動させることによるアクチュエータの負荷の増大を防ぐことができるからである。 This most results in the first lens unit L1 disposed on the object side to motions in focusing, increase in the front lens diameter, the load of the actuator due to lens weight moves the heaviest first lens unit L1 This is because it is possible to prevent an increase. また、フォーカスのために第1レンズ群L1を移動させないことで、第1レンズ群L1と第2レンズ群L2とをカム等で単純に連携してズーミングに際して移動させることが可能となり、メカ構造の簡素化及び精度向上も達成できる。 Also, by not moving the first lens unit L1 for focusing, the first lens unit L1 and the second lens unit L2 becomes possible to move during zooming and simply cooperate with a cam or the like, the mechanical structure simplification and accuracy improvement can be achieved.

また、第3レンズ群L3にてフォーカシングを行う場合、広角端から望遠端へのズーミングに際して第3レンズ群L3を像側に移動させることにより、フォーカシング移動量の大きい望遠端での第3レンズ群L3の位置を広角端に比して像側に配置することができるため、ズーミング及びフォーカシングで必要となる第3レンズ群L3の移動量の総和を最小とすることが可能となり、レンズ系のコンパクト化に有効である。 When performing the focusing by the third lens unit L3, by moving the third lens unit L3 on the image side during zooming from the wide-angle end to the telephoto end, the third lens group with a large telephoto end the focusing movement amount since the position of L3 can be disposed on the image side than the wide angle end, it is possible to minimize the moving amount of the sum of the third lens unit L3 which is required in zooming and focusing, a compact lens system it is effective in reduction.

次に、本実施形態のズームレンズにおいて、良好なる光学性能を得るため、またはレンズ系全体の小型化を図るために、好ましい条件について説明する。 Then, in the zoom lens of the present embodiment, in order to obtain a good optical performance, or in order to entire lens system compact, it is described preferable conditions.

(a)レンズ沈胴長及びレンズ外径短縮のためには、以下の条件を満足するのが好ましい。 For (a) the lens retracted length and outer diameter of the lens shortened, it is preferable to satisfy the following condition.
4.5<(β2t・L2t)/(β2w・L1w)<10.0 …(1) 4.5 <(β2t · L2t) / (β2w · L1w) <10.0 ... (1)
ここで、β2wは第2レンズ群L2の広角端での結像倍率、β2tは第2レンズ群L2の望遠端での結像倍率、L1wは第1レンズ群L1と第2レンズ群L2の広角端での間隔、L2tは第2レンズ群L2と第3レンズ群L3の望遠端での間隔である。 Here, .beta.2w the imaging magnification at the wide angle end of the second lens unit L2,? 2t is an imaging magnification at the telephoto end of the second lens unit L2, L1W the first lens unit L1 angle of the second lens unit L2 interval at the end, L2t is the spacing between the second lens unit L2 telephoto end of the third lens unit L3.

条件式(1)の下限値を越えると、広角端における第1レンズ群L1と第2レンズ群L2の間隔が相対的に広がることになり、第1レンズ群L1のレンズ径が増大するため好ましくない。 If the lower limit value of conditional expression (1), will be the distance between the first lens unit L1 at the wide angle end the second lens unit L2 is spread relatively preferable because the lens diameter of the first lens unit L1 is increased Absent. また、条件式(1)の上限値を越えると、広角端に対して望遠端のレンズ全長が相対的に長くなり、沈胴長を十分短くすることができなくなる。 Further, if the upper limit value of conditional expression (1), the total lens length at the telephoto end is relatively longer than the wide angle end, it becomes impossible to sufficiently reduce the collapsed length.

更に好ましくは、条件式(1)の数値範囲を次の如くするのが良い。 More preferably, the numerical range of the conditional expression (1) had better be as follows.
5.0<β2t・L2t/(β2w・L1w)<8.0 …(1a) 5.0 <β2t · L2t / (β2w · L1w) <8.0 ... (1a)
(b)レンズ沈胴長短縮のためには、以下の条件を満足するのが好ましい。 (B) for the lens retracted length shortening is preferable to satisfy the following condition.
0.2< D2S/D2R <0.9 …(2) 0.2 <D2S / D2R <0.9 ... (2)
ここで、D2Sは第2レンズ群L2の最も物体側に配置されたレンズの物体側頂点とFナンバー決定部材(開口絞りSP)との光軸方向の間隔、D2Rは第2レンズ群L2の最も物体側に配置されたレンズの物体側頂点と、そのレンズの物体側の面とレンズ端面(コバ面)との交点との光軸方向の間隔である。 Here, D2S the optical axis direction of the distance between the object-side vertex and F-number determining member of a lens disposed on the most object side in the second lens group L2 (aperture stop SP), D2R most of the second lens unit L2 the object side apex of the lens disposed on the object side, a distance between the optical axis direction between the intersection of the object side of the lens end face of the lens (edge ​​surface).

条件式(2)の下限値を超えると、第1レンズ群L1の最も像側に配置されたメニスカス正レンズの像側のレンズ面と第2レンズ群L2の鏡筒の物体側の面が干渉することとなり、十分な沈胴長の短縮を図ることができず好ましくない。 If the lower limit value of conditional expression (2), the most object side surface of the lens barrel of the lens surface on the image side of the deployed meniscus positive lens on the image side and a second lens unit L2 in the first lens unit L1 interference it and will be unfavorable can not be shortened sufficiently collapsed length. また、条件式(2)の上限値を超えると、Fナンバー決定部材から第1レンズ群L1までの距離が長くなり、第1レンズ群L1のレンズ径が増大するため好ましくない。 If it exceeds the upper limit of the condition (2), the distance from the F-number determining member to the first lens unit L1 is increased, undesirably lens diameter of the first lens unit L1 is increased.

更に好ましくは、条件式(2)の数値範囲を次の如くするのが良い。 More preferably, the numerical range of the conditional expression (2) had better be as follows.
0.3< D2S/D2R <0.8 …(2a) 0.3 <D2S / D2R <0.8 ... (2a)
(c)レンズ全長短縮のためには、以下の条件を満足するのが好ましい。 For (c) total lens length shortened, it is preferable to satisfy the following condition.
4.5<√(ft/L1t)<10.0 …(3) 4.5 <√ (ft / L1t) <10.0 ... (3)
ここで、ftは全系の望遠端での焦点距離、L1tは第1レンズ群L1と第2レンズ群L2の望遠端での間隔である。 Here, ft is the focal length of the entire system at a telephoto limit, L1t is the spacing between the first lens unit L1 telephoto end of the second lens unit L2.

条件式(3)の下限値を越えると、望遠端における第1レンズ群L1と第2レンズ群L2の間隔が広がるため、レンズ全長が伸びるため好ましくない。 If the lower limit value of conditional expression (3), since the widened distance between the first lens unit L1 and the second lens unit L2 at the telephoto end is not preferable because the total lens length is extended. また、条件式(3)の上限値を越えると、望遠端において第1レンズ群L1と第2レンズ群L2の間隔が近くなりすぎ、製造誤差により第1レンズ群L1と第2レンズ群L2とが機械的に干渉する可能性が生じるため好ましくない。 Further, if the upper limit value of conditional expression (3), a first lens unit L1 at the telephoto end becomes too close distance between the second lens unit L2, the manufacturing error and the first lens unit L1 and the second lens unit L2 There is not preferable because the resulting mechanical interference possibilities.

更に好ましくは、条件式(3)の数値範囲を次の如くするのが良い。 More preferably, conditional expression (3) the numerical range is good to as next.

5.0<√(ft/L1t)<8.0 …(3a) 5.0 <√ (ft / L1t) <8.0 ... (3a)
(d)高ズーム比化及びレンズ沈胴長短縮のためには、以下の条件を満足するのが好ましい。 To shorten (d) a high zoom ratio and lens retracted length, preferably satisfies the following condition.
1.0<β3t/β3w<1.3 …(4) 1.0 <β3t / β3w <1.3 ... (4)
ここで、β3wは第3レンズ群L3の広角端における結像倍率、β3tは第3レンズ群L3の望遠端における結像倍率である。 Here,? 3w the imaging magnification at the wide angle end of the third lens unit L3, [beta] 3t is an imaging magnification at the telephoto end of the third lens unit L3. なお、結像倍率は無限遠物体合焦時のものである。 Incidentally, the imaging magnification are those at the time of infinite object if.

条件式(4)の下限値を越えると、第3レンズ群L3によるズーム比の増倍効果が失われ、ズーム比の高倍化に対して不利な方向となるため好ましくない。 If the lower limit value of conditional expression (4), the multiplication effect of the zoom ratio of the third lens unit L3 is lost, undesirably become unfavorable direction for high magnification of the zoom ratio. また、条件式(4)の上限値を越えると、広角端から望遠端における第3レンズ群L3の移動量が増えるので、第3レンズ群L3の可動スペースを多く確保しなければならず、沈胴長の短縮に不利な方向となるため好ましくない。 Further, if the upper limit value of conditional expression (4), the moving amount of the third lens unit L3 at the telephoto end from the wide-angle end is increased, it is necessary to ensure a large amount of moving space of the third lens unit L3, collapsed undesirably becomes unfavorable direction for shortening the length.

更に好ましくは、条件式(4)の数値範囲を次の如くするのが良い。 More preferably, the numerical range of the conditional expression (4) had better be as follows.
1.0<β3t/β3w<1.2 …(4a) 1.0 <β3t / β3w <1.2 ... (4a)
(e)レンズ全長短縮のためには、以下の条件を満足するのが好ましい。 For (e) the total lens length shortened, it is preferable to satisfy the following condition.
−0.7<(R2f+R2r)/(R2f−R2r)<−0.35 …(5) -0.7 <(R2f + R2r) / (R2f-R2r) <- 0.35 ... (5)
ここで、R2fは第2レンズ群L2の最も物体側に配置されたレンズの物体側の面の近軸曲率半径、R2rは第2レンズ群L2の最も像側に配置されたレンズの像側の近軸曲率半径である。 Here, R2f is the paraxial radius of curvature of the object side surface of the lens disposed on the most object side of the second lens unit L2, R2r is the image side of the lens disposed on the most image side of the second lens unit L2 it is the paraxial radius of curvature.

条件式(5)の下限値を越えると、球面収差が補正不足となり好ましくない。 If the lower limit value of conditional expression (5) is undesirable spherical aberration becomes under-corrected. また、条件式(5)の上限値を越えると、特に望遠端でのバックフォーカスが確保できなくなるため好ましくない。 Further, if the upper limit value of conditional expression (5), particularly undesirable because the back focus can not be ensured at the telephoto end.

更に好ましくは、条件式(5)の数値範囲を次の如くするのが良い。 More preferably, the numerical range of the conditional expression (5) had better be as follows.
−0.65<(R2f+R2r)/(R2f−R2r)<−0.4 …(5a) -0.65 <(R2f + R2r) / (R2f-R2r) <- 0.4 ... (5a)
以上のように、各レンズ群を所望の屈折力配置と収差補正とを両立するレンズ構成とすることにより、良好な性能を保ちつつ、レンズ系のコンパクト化を達成している。 As described above, by the lens configuration of each lens group to achieve both the desired refractive power arrangement and the aberration correction, while maintaining good performance, we have achieved compactness of the lens system.

次に実施例1〜3に対応する数値実施例1〜3の数値データを示す。 Next, numerical data of the numerical examples 1 to 3 corresponding to Examples 1-3. 数値実施例において、fは焦点距離、FnoはFナンバー、ωは半画角である。 In Numerical Example, f is the focal length, Fno represents the F-number, omega denotes a half field angle. iは物体側より数えた順序を示し、Riは第i番目の面の曲率半径、Diは第i番目の面と第(i+1)番目の面との軸上間隔、Niとνdiは各々第i番目の材料のd線を基準とした屈折率とアッベ数である。 i denotes an order counted from the object side, Ri denotes a curvature of the i-th surface radius, Di is the axial distance between the i-th surface and the (i + 1) -th surface, Ni and νdi each i-th the refractive index and Abbe number based on the d-line of th material.

非球面形状は、光の進行方向を正とし、Xを光軸方向の面頂点からの変位量、hを光軸と垂直な方向の光軸からの高さ、Rを近軸曲率半径、kを円錐定数、B〜Eを各々非球面係数とするとき、 Aspheric shape, the traveling direction of light is positive, the displacement amount from a surface vertex in the optical axis direction X, h perpendicular to the optical axis direction of the height from the optical axis, paraxial radius of curvature R, k conic constant, when the respective aspherical coefficients B~E a

なる式で表している。 Made are represented by formula. なお「e±Z」は「×10 ±Z 」を意味する。 The "e ± Z" means "× 10 ± Z".

又前述の各条件式と数値実施例の関係を第1表に示す。 Further illustrating the relationship between the conditional expressions and numerical embodiments described above in Table 1.

(数値実施例1) (Numerical Example 1)
f=4.715〜16.774 Fno=2.85〜5.97 2ω=73.9°〜23.9° f = 4.715~16.774 Fno = 2.85~5.97 2ω = 73.9 ° ~23.9 °
R 1 = 50.030 D 1 = 1.35 N 1 = 1.88300 νd1 = 40.8 R 1 = 50.030 D 1 = 1.35 N 1 = 1.88300 νd1 = 40.8
R 2 = 4.759 D 2 = 2.24 R 2 = 4.759 D 2 = 2.24
R 3 = 8.594 D 3 = 1.60 N 2 = 1.92286 νd2 = 18.9 R 3 = 8.594 D 3 = 1.60 N 2 = 1.92286 νd2 = 18.9
R 4 = 16.681 D 4 = 可変 R 4 = 16.681 D 4 = variable
R 5 = 絞り D 5 = -0.50 R 5 = aperture D 5 = -0.50
R 6 = 4.338 D 6 = 2.00 N 3 = 1.77250 νd3 = 49.6 R 6 = 4.338 D 6 = 2.00 N 3 = 1.77250 νd3 = 49.6
R 7 = 8.707 D 7 = 0.50 N 4 = 1.64769 νd4 = 33.8 R 7 = 8.707 D 7 = 0.50 N 4 = 1.64769 νd4 = 33.8
R 8 = 3.832 D 8 = 0.48 R 8 = 3.832 D 8 = 0.48
R 9 = 9.572 D 9 = 0.50 N 5 = 1.76182 νd5 = 26.5 R 9 = 9.572 D 9 = 0.50 N 5 = 1.76182 νd5 = 26.5
R10 = 3.897 D10 = 2.00 N 6 = 1.60311 νd6 = 60.6 R10 = 3.897 D10 = 2.00 N 6 = 1.60311 νd6 = 60.6
R11 = -11.842 D11 = 可変 R11 = -11.842 D11 = variable
R12 = 12.540 D12 = 1.60 N 7 = 1.60311 νd7 = 60.6 R12 = 12.540 D12 = 1.60 N 7 = 1.60311 νd7 = 60.6
R13 = 89.899 D13 = 可変 R13 = 89.899 D13 = variable
R14 = ∞ D14 = 1.40 N 8 = 1.51633 νd8 = 64.1 R14 = ∞ D14 = 1.40 N 8 = 1.51633 νd8 = 64.1
R15 = ∞ R15 = ∞

非球面係数 (第1面) Aspherical coefficients (first surface)
k=0.00000e+00 k = 0.00000e + 00
B=4.56667e-04 C=-7.14952e-06 D=4.76420e-08 B = 4.56667e-04 C = -7.14952e-06 D = 4.76420e-08
(第2面) (Second surface)
k=-1.53849e+00 k = -1.53849e + 00
B=1.59706e-03 C=1.32234e-05 D=-3.93707e-07 E=1.11975e-09 B = 1.59706e-03 C = 1.32234e-05 D = -3.93707e-07 E = 1.11975e-09
(第6面) (Sixth surface)
k=-4.37828e-01 k = -4.37828e-01
B=-2.86734e-06 C=8.92384e-06 B = -2.86734e-06 C = 8.92384e-06

(数値実施例2) (Numerical Example 2)
f=6.005〜21.002 Fno=2.62〜5.60 2w=61.2°〜19.2° f = 6.005~21.002 Fno = 2.62~5.60 2w = 61.2 ° ~19.2 °
R 1 = 14.916 D 1 = 1.20 N 1 = 1.88300 νd1 = 40.8 R 1 = 14.916 D 1 = 1.20 N 1 = 1.88300 νd1 = 40.8
R 2 = 4.222 D 2 = 1.34 R 2 = 4.222 D 2 = 1.34
R 3 = 6.744 D 3 = 1.90 N 2 = 1.84666 νd2 = 23.9 R 3 = 6.744 D 3 = 1.90 N 2 = 1.84666 νd2 = 23.9
R 4 = 12.586 D 4 = 可変 R 4 = 12.586 D 4 = variable
R 5 = 絞り D 5 = -0.65 R 5 = aperture D 5 = -0.65
R 6 = 4.347 D 6 = 2.00 N 3 = 1.88300 νd3 = 40.8 R 6 = 4.347 D 6 = 2.00 N 3 = 1.88300 νd3 = 40.8
R 7 = 63.098 D 7 = 0.60 N 4 = 1.80518 νd4 = 25.4 R 7 = 63.098 D 7 = 0.60 N 4 = 1.80518 νd4 = 25.4
R 8 = 3.531 D 8 = 0.64 R 8 = 3.531 D 8 = 0.64
R 9 = 12.745 D 9 = 1.40 N 5 = 1.69680 νd5 = 55.5 R 9 = 12.745 D 9 = 1.40 N 5 = 1.69680 νd5 = 55.5
R10 = -18.733 D10 = 可変 R10 = -18.733 D10 = variable
R11 = 17.228 D11 = 1.40 N 6 = 1.69680 νd6 = 55.5 R11 = 17.228 D11 = 1.40 N 6 = 1.69680 νd6 = 55.5
R12 = -97.710 D12 = 可変 R12 = -97.710 D12 = variable
R13 = ∞ D13 = 1.90 N 7 = 1.51633 νd7 = 64.1 R13 = ∞ D13 = 1.90 N 7 = 1.51633 νd7 = 64.1
R14 = ∞ R14 = ∞

非球面係数 (第1面) Aspherical coefficients (first surface)
k=0.00000e+00 k = 0.00000e + 00
B=-5.40012e-04 C=1.51938e-05 D=-1.52986e-07 B = -5.40012e-04 C = 1.51938e-05 D = -1.52986e-07
(第2面) (Second surface)
k=-1.34784e+00 k = -1.34784e + 00
B=6.88013e-04 C=1.50185e-05 D=5.06277e-07 B = 6.88013e-04 C = 1.50185e-05 D = 5.06277e-07
(第6面) (Sixth surface)
k=-2.84476e-01 k = -2.84476e-01
B=-6.29759e-05 C=-8.41757e-06 B = -6.29759e-05 C = -8.41757e-06

(数値実施例3) (Numerical Example 3)
f=6.048〜21.255 Fno=2.71〜5.74 2w=73.2°〜23.9° f = 6.048~21.255 Fno = 2.71~5.74 2w = 73.2 ° ~23.9 °
R 1 = 71.340 D 1 = 1.60 N 1 = 1.88300 νd1 = 40.8 R 1 = 71.340 D 1 = 1.60 N 1 = 1.88300 νd1 = 40.8
R 2 = 5.719 D 2 = 2.75 R 2 = 5.719 D 2 = 2.75
R 3 = 10.800 D 3 = 1.70 N 2 = 1.92286 νd2 = 18.9 R 3 = 10.800 D 3 = 1.70 N 2 = 1.92286 νd2 = 18.9
R 4 = 22.275 D 4 = 可変 R 4 = 22.275 D 4 = variable
R 5 = 絞り D 5 = -0.50 R 5 = aperture D 5 = -0.50
R 6 = 5.049 D 6 = 2.30 N 3 = 1.80610 νd3 = 40.7 R 6 = 5.049 D 6 = 2.30 N 3 = 1.80610 νd3 = 40.7
R 7 = -60.222 D 7 = 0.50 N 4 = 1.69895 νd4 = 30.1 R 7 = -60.222 D 7 = 0.50 N 4 = 1.69895 νd4 = 30.1
R 8 = 4.267 D 8 = 0.70 R 8 = 4.267 D 8 = 0.70
R 9 = 10.417 D 9 = 0.50 N 5 = 1.76182 νd5 = 26.5 R 9 = 10.417 D 9 = 0.50 N 5 = 1.76182 νd5 = 26.5
R10 = 5.329 D10 = 2.20 N 6 = 1.51633 νd6 = 64.1 R10 = 5.329 D10 = 2.20 N 6 = 1.51633 νd6 = 64.1
R11 = -12.663 D11 = 可変 R11 = -12.663 D11 = variable
R12 = 12.931 D12 = 1.80 N 7 = 1.60311 νd7 = 60.6 R12 = 12.931 D12 = 1.80 N 7 = 1.60311 νd7 = 60.6
R13 = 58.859 D13 = 可変 R13 = 58.859 D13 = variable
R14 = ∞ D14 = 1.40 N 8 = 1.51633 νd8 = 64.1 R14 = ∞ D14 = 1.40 N 8 = 1.51633 νd8 = 64.1
R15 = ∞ R15 = ∞

非球面係数 (第1面) Aspherical coefficients (first surface)
k=0.00000e+00 k = 0.00000e + 00
B=2.58911e-04 C=-2.62258e-06 D=1.30274e-08 B = 2.58911e-04 C = -2.62258e-06 D = 1.30274e-08
(第2面) (Second surface)
k=-1.21325e+00 k = -1.21325e + 00
B=6.70859e-04 C=5.95470e-06 D=-5.54523e-08 E=1.33713e-10 B = 6.70859e-04 C = 5.95470e-06 D = -5.54523e-08 E = 1.33713e-10
(第6面) (Sixth surface)
k=-3.46473e-01 B=-8.50982e-05 C=4.56506e-07 k = -3.46473e-01 B = -8.50982e-05 C = 4.56506e-07

本実施形態のズームレンズは、以上説明したように各要素を設定することにより、特に、固体撮像素子を用いた撮影系に好適な、構成レンズ枚数が少なくコンパクトで、特に沈胴ズームレンズに適した、ズーム比が3倍以上の優れた光学性能を有するズームレンズが達成できる。 The zoom lens of the present embodiment, by setting each element as described above, in particular, suitable for photographic system using a solid-number of lens elements is at least compact, particularly suitable for retractable zoom lens , the zoom lens zoom ratio has more than three times superior optical performance can be achieved.

また、レンズ群中に効果的に非球面を導入することによって、軸外諸収差、特に非点収差・歪曲収差および大口径比化した際の球面収差の補正が効果的に行える。 Further, by introducing effectively non-spherical in the lens group, off-axis aberrations, especially correction of spherical aberration when the astigmatism, distortion, and a large aperture ratio allows effective.

次に本発明のズームレンズを撮影光学系として用いたデジタルスチルカメラ(撮像装置)の実施形態を、図7を用いて説明する。 Next an embodiment of a digital still camera (image pickup apparatus) using the zoom lens of the present invention as a photographic optical system will be described with reference to FIG.

図7において、20はカメラ本体、21は実施例1〜3で説明したいずれかのズームレンズによって構成された撮影光学系、22はカメラ本体に内蔵され、撮影光学系21によって形成された被写体像を受光するCCDセンサやCMOSセンサ等の固体撮像素子(光電変換素子)、23は固体撮像素子22によって光電変換された被写体像に対応する情報を記録するメモリ、24は液晶ディスプレイパネル等によって構成され、固体撮像素子22上に形成された被写体像を観察するためのファインダである。 7, 20 denotes a camera body, 21 Examples 1 to 3 either been photographing optical system constituted by the zoom lens described in, 22 is incorporated in the camera body, the subject image formed by the imaging optical system 21 solid-state image sensor such as a CCD sensor or a CMOS sensor for receiving the (photoelectric conversion element), 23 a memory for recording information corresponding to the object image photoelectrically converted by the solid-state imaging device 22, 24 includes a liquid crystal display panel or the like a finder for observing the object image formed on the solid-state imaging device 22.

このように本発明のズームレンズをデジタルスチルカメラ等の撮像装置に適用することにより、小型で高い光学性能を有する撮像装置が実現できる。 By applying the zoom lens of the present invention to an image pickup apparatus such as a digital still camera, a compact image pickup apparatus having high optical performance can be realized.

実施例1のズームレンズのレンズ断面図である。 It is a lens sectional view of a zoom lens of Embodiment 1. 実施例1のズームレンズの収差図である。 It is an aberration diagram of a zoom lens of Embodiment 1. 実施例2のズームレンズのレンズ断面図である。 It is a lens sectional view of a zoom lens according to a second embodiment. 実施例2のズームレンズの収差図である。 It is an aberration diagram of a zoom lens according to a second embodiment. 実施例3のズームレンズのレンズ断面図である。 It is a sectional view of a zoom lens of Example 3. 実施例3のズームレンズの収差図である。 It is an aberration diagram of the zoom lens of Embodiment 3. デジタルスチルカメラの要部概略図である。 A schematic view of a digital still camera.

符号の説明 DESCRIPTION OF SYMBOLS

L1 第1レンズ群 L2 第2レンズ群 L3 第3レンズ群 L2a 第2aレンズ群 L2a 第2bレンズ群 SP 開口絞り(Fナンバー決定部材) L1 first lens group L2 second lens unit L3 third lens group L2a the 2a lens group L2a the 2b lens group SP aperture (F-number determining member)
IP 像面 G ガラスブロック d d線 g g線 S サジタル像面 M メリジオナル像面 IP image plane G glass block d d line g g line S a sagittal image surface M meridional image plane

Claims (12)

  1. 物体側より像側へ順に、負の屈折力の第1レンズ群、正の屈折力の第2レンズ群、正の屈折力の第3レンズ群を有し、ズーミングに際し各群の間隔が変化するズームレンズにおいて、前記第1レンズ群は、1枚の負レンズと1枚の正レンズから成り、前記第2レンズ群は、1枚の正レンズと1枚の負レンズから成る第2aレンズ群と、第2aレンズ群の像側に配置され、少なくとも1枚の正レンズを有する第2bレンズ群から成り、前記第3レンズ群は、少なくとも1枚の正レンズを有すると共に、前記第2レンズ群の広角端での結像倍率をβ2w、望遠端での結像倍率をβ2t、前記第1レンズ群と前記第2レンズ群の広角端での間隔をL1w、前記第2レンズ群と第3レンズ群の望遠端での間隔L2tとするとき、 In order from the object side to the image side, a first lens unit having a negative refractive power, a second lens unit having positive refractive power, a third lens unit having a positive refractive power, the interval of each group is changed upon zooming in the zoom lens, the first lens group consists of one negative lens and one positive lens, the second lens group includes a first 2a lens group including one positive lens and one negative lens , disposed on the image side of the 2a lens group consists the 2b lens group having at least one positive lens, the third lens group, and having at least one positive lens, the second lens group β2w imaging magnification at the wide angle end,? 2t imaging magnification at the telephoto end, the first lens group and the second lens group L1w the interval at the wide angle end, the second lens group and the third lens group when the interval L2t at the telephoto end,
    4.5<(β2t・L2t)/(β2w・L1w)<10.0 4.5 <(β2t · L2t) / (β2w · L1w) <10.0
    なる条件を満足することを特徴とするズームレンズ。 Zoom lens satisfies the following condition.
  2. 前記第2レンズ群中で最も物体側に配置された正レンズの物体側頂点と、その正レンズの物体側の面とその正レンズとの端面との交点との間に、開放Fナンバーの光束を決定するFナンバー決定部材を有することを特徴とする請求項1のズームレンズ。 The object side apex of the positive lens arranged on the most object side in the second lens group, between the intersection of the end surface of the object side surface of the positive lens and its positive lens, the light flux of the open F-number the zoom lens according to claim 1, characterized in that it has a F-number determining member for determining a.
  3. 前記第2レンズ群中で最も物体側に配置された正レンズの物体側頂点と、前記Fナンバー決定部材との光軸方向の間隔をD2S、前記第2レンズ群中で最も物体側に配置された正レンズの物体側頂点と、その正レンズの物体側の面とその正レンズの端面との交点の光軸方向の間隔をD2Rとするとき、 The object side apex of the positive lens arranged on the most object side in the second lens group, D2S apart in the optical axis direction between the F-number determining member, it is disposed most on the object side in the second lens group the object side apex of the positive lens, when the object-side surface of the positive lens and its positive lens distance in the optical axis direction of the intersection of the end face of D2R,
    0.2< D2S/D2R <0.9 0.2 <D2S / D2R <0.9
    なる条件を満足することを特徴とする請求項2のズームレンズ。 The zoom lens according to claim 2, characterized by satisfying the following condition.
  4. 広角端から望遠端へのズーミングに際し、前記第1レンズ群は像側に凸状の軌跡で移動し、前記第2レンズ群は単調に物体側に移動し、前記第3レンズ群は像側に移動することを特徴とする請求項1〜3いずれかのズームレンズ。 During zooming from the wide-angle end to the telephoto end, the first lens unit moves with a locus convex toward the image side, the second lens unit moves monotonically toward the object side, the third lens group on the image side It claims 1-3 or a zoom lens, characterized by moving.
  5. 前記第1レンズ群中の負レンズは、物体側と像側の両面が非球面形状であることを特徴とする請求項1〜4いずれかのズームレンズ。 Wherein the negative lens in the first lens group, one of the zoom lens according to claim 1, wherein the both surfaces of the object side and the image side are aspherical.
  6. 前記第2aレンズ群は、正レンズと負レンズを接合した接合レンズであることを特徴とする請求項1〜5いずれかのズームレンズ。 The 2a lens group, one of the zoom lens according to claim 5, characterized in that the cemented lens in which a positive lens and a negative lens.
  7. 全系の望遠端での焦点距離をft、前記第1レンズ群と第2レンズ群の望遠端での間隔をL1tとするとき、 When the focal length of the entire system at a telephoto limit ft, the distance at the telephoto end of the first lens group and the second lens group and L1t,
    4.5<√(ft/L1t)<10.0 4.5 <√ (ft / L1t) <10.0
    なる条件を満足することを特徴とする請求項1〜6いずれかのズームレンズ。 Any of the zoom lens according to claim 1 to 6, characterized by satisfying the following condition.
  8. 前記第3レンズ群の広角端での結像倍率をβ3w、望遠端での結像倍率をβ3tとするとき、 When the imaging magnification at the wide angle end of the third lens group? 3w, and β3t the imaging magnification at the telephoto end,
    1.0<β3t/β3w<1.3 1.0 <β3t / β3w <1.3
    なる条件を満足することを特徴とする請求項1〜7いずれかのズームレンズ。 It claims 1-7 or of a zoom lens which satisfies the following condition.
  9. 前記第2レンズ群中で最も物体側に配置されたレンズの物体側面の近軸曲率半径をR2f、前記第2レンズ群中で最も像側に配置されたレンズの像側の近軸曲率半径をR2rとするとき、 Paraxial radius of curvature R2f of the object side surface of the second lens closest to the object side in the lens disposed in groups, the paraxial curvature radius of the image side of the second lens closest to the image side in the lens disposed in the group when the R2r,
    −0.7<(R2f+R2r)/(R2f−R2r)<−0.35 -0.7 <(R2f + R2r) / (R2f-R2r) <- 0.35
    なる条件を満足することを特徴とする請求項1〜8いずれかのズームレンズ。 Any of the zoom lens according to claim 1 to 8, characterized by satisfying the following condition.
  10. 前記第3レンズ群を物体側に移動させて無限遠物体から近距離物体へのフォーカシングを行うことを特徴とする請求項1〜9いずれかのズームレンズ。 It claims 1-9 or a zoom lens, characterized in that performing the focusing on the close range object the third lens group is moved toward the object side from infinity.
  11. 光電変換素子上に像を形成することを特徴とする請求項1〜10いずれかのズームレンズ。 Any of the zoom lens according to claim 1, wherein the forming an image on a photoelectric conversion element.
  12. 請求項1〜11いずれかのズームレンズと、該ズームレンズが形成する像を受光する光電変換素子とを有することを特徴とする撮像装置。 And any of the zoom lens according to claim 1 to 11, an imaging apparatus characterized by comprising a photoelectric conversion element for receiving an image of the zoom lens is formed.
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