JP4794935B2

JP4794935B2 - Zoom lens

Info

Publication number: JP4794935B2
Application number: JP2005214451A
Authority: JP
Inventors: 威志西村
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2005-07-25
Filing date: 2005-07-25
Publication date: 2011-10-19
Anticipated expiration: 2025-07-25
Also published as: JP2007033643A

Description

本発明は銀塩フィルムカメラ、電子記録方式のデジタルカメラやビデオカメラ等に最適なズームレンズに関し、イメージサークルに対して比較的バックフォーカスが長いカメラに最適な屈折力配置や構成を設定することにより、高い光学性能と小型化が図られたズームレンズに関するものである。 The present invention relates to a zoom lens optimal for a silver salt film camera, an electronic recording digital camera, a video camera, and the like, by setting an optimal refractive power arrangement and configuration for a camera having a relatively long back focus with respect to an image circle. The present invention relates to a zoom lens with high optical performance and miniaturization.

近年、一眼レフカメラやレンズシャッターカメラ、デジタルスチルカメラ、ビデオカメラ等の小型化に伴い、これらに使用される撮影レンズとしてレンズ全長が短くコンパクトなズームレンズが要望されている。また、デジタル一眼レフカメラが普及するに伴い、焦点距離に比してバックフォーカスの長い光学系が求められている。 In recent years, with the miniaturization of single-lens reflex cameras, lens shutter cameras, digital still cameras, video cameras, and the like, compact zoom lenses with a short overall lens length are demanded as photographing lenses used for these cameras. In addition, with the spread of digital single-lens reflex cameras, an optical system having a long back focus compared to the focal length is required.

物体側より順に正、負、正、そして正の屈折力のレンズ群の４つのレンズ群より成り、各レンズ群を少枚数のレンズで構成する一方第３レンズ群以降に２面以上の非球面を配置することなどにより、コンパクトで広画角のズーム比３倍以上のズームレンズが知られている（例えば、特許文献１）。 It consists of four lens groups of positive, negative, positive, and positive refractive power lens groups in order from the object side, and each lens group is composed of a small number of lenses, while two or more aspheric surfaces after the third lens group. A zoom lens having a compact and wide angle of view and a zoom ratio of 3 times or more is known (for example, Patent Document 1).

また、物体側より順に正、負、正、そして正の屈折力のレンズ群の４つのレンズ群より成り、各レンズ群の構成枚数を限定して、且つ屈折力配分も規定することなどにより、コンパクトで広画角のズーム比３．５倍程度までのズームレンズが知られている（例えば特許文献２、特許文献３）。 In addition, in order from the object side, it consists of four lens groups of positive, negative, positive, and positive refractive power lens groups, by limiting the number of components of each lens group and defining the refractive power distribution, etc. Zoom lenses having a compact and wide angle of view up to about 3.5 times are known (for example, Patent Document 2 and Patent Document 3).

また、物体側より順に正、負、正、そして正の屈折力のレンズ群の４つのレンズ群より成り、第３群を正レンズ１枚で構成した高変倍率のズームレンズが知られている（例えば特許文献４、特許文献５、特許文献６）。
特開平８−２２０４３９号公報特開平９−１８４９８２号公報特開２００４−３３３７７０号公報特開平８−３２７８７３号公報特開平９−１２７４１７号公報特開２００４−２４０１５１号公報 Further, there is known a zoom lens having a high zoom ratio, which is composed of four lens groups of positive, negative, positive, and positive refractive power groups in order from the object side, and the third group is composed of one positive lens. (For example, Patent Document 4, Patent Document 5, and Patent Document 6).
JP-A-8-220439 Japanese Patent Laid-Open No. 9-184982 JP 2004-333770 A JP-A-8-327873 JP-A-9-127417 Japanese Patent Laid-Open No. 2004-240151

一般にズームレンズにおいて、レンズ系全体の小型化を図りつつ、所定の変倍比を有しつつ、全変倍範囲にわたり良好なる光学性能を得るには、各レンズ群のレンズ構成を適切に設定する必要がある。ズームレンズにおいて、各レンズ群の屈折力を強めれば変倍における各レンズ群の移動量が少なくなり、レンズ全長の短縮化が可能となる。しかしながら、各レンズ群の屈折力を単に強めると変倍に伴う収差変動が大きくなり、これを良好に補正するのが難しくなってくるという問題点が生じてくる。 In general, in a zoom lens, in order to obtain a good optical performance over the entire zoom range while having a predetermined zoom ratio while reducing the size of the entire lens system, the lens configuration of each lens group is appropriately set. There is a need. In a zoom lens, if the refractive power of each lens group is increased, the amount of movement of each lens group during zooming can be reduced, and the overall length of the lens can be shortened. However, if the refractive power of each lens group is simply increased, the aberration fluctuation accompanying the zooming becomes large, and it becomes difficult to correct this well.

前記特許文献１で開示されているズームレンズでは、４つあるレンズ群の全てが３枚以下のレンズで構成されていて全体のレンズ枚数も少なくコンパクトではあるが、その一方で、屈折力の強い非球面レンズを比較的製造の難しいガラス材質で形成したものを２枚以上は使用している。この為、製造が難しくなる傾向があった。 In the zoom lens disclosed in Patent Document 1, all four lens groups are composed of three or less lenses and the total number of lenses is small and compact, but on the other hand, the refractive power is strong. Two or more aspherical lenses made of a glass material that is relatively difficult to manufacture are used. For this reason, the manufacturing tends to be difficult.

前記特許文献２に開示されているズームレンズは、少枚数構成で４群ズームレンズを達成しているが、変倍比が３倍を超えるような場合はやはり非球面レンズを２枚使用する必要がある。この為、製造が難しくなる傾向にあった。また、光学系の中で最も大きな口径を有している第１レンズ群が、比較的強い正の屈折力を持っているために曲率の強いレンズ形状を有しており、そのためにレンズの加工が難しくなる傾向があった。特に正、負、正そして正の屈折力のレンズ群の４つのレンズ群より成る４群ズームレンズにおいて、高変倍率でレンズ枚数が少ない小型のレンズ系を達成するにはズーミングに伴う各レンズ群の移動条件や各レンズ群の屈折力等を適切に設定する必要がある。これらが満足されないと諸収差の発生が増大し、全変倍範囲にわたり良好なる画質の映像を得るのが難しくなってくる。 Although the zoom lens disclosed in Patent Document 2 achieves a four-group zoom lens with a small number of lenses, it is necessary to use two aspherical lenses when the zoom ratio exceeds three times. There is. For this reason, the manufacturing tends to be difficult. In addition, the first lens group having the largest aperture in the optical system has a relatively strong positive refractive power and thus has a lens shape with a strong curvature. Tended to be difficult. In particular, in a four-group zoom lens composed of four lens groups of positive, negative, positive and positive refractive power, each lens group associated with zooming is required to achieve a small lens system with a high zoom ratio and a small number of lenses. It is necessary to appropriately set the movement conditions and the refractive power of each lens group. If these are not satisfied, the occurrence of various aberrations increases, making it difficult to obtain an image with good image quality over the entire zoom range.

前記特許文献３に開示されているズームレンズは、少枚数構成で４群ズームレンズを達成している。しかしながら、焦点距離に比してバックフォーカスが短いので良くない。 The zoom lens disclosed in Patent Document 3 achieves a four-group zoom lens with a small number of lenses. However, this is not good because the back focus is shorter than the focal length.

前記特許文献４に開示されているズームレンズは、少枚数構成で４群ズームレンズを達成している。第３群を正レンズ１枚で構成しており、焦点距離に比してバックフォーカスも十分確保されているものの、光学全長が長いため小型化においては達成できていなかった。 The zoom lens disclosed in Patent Document 4 achieves a four-group zoom lens with a small number of lenses. Although the third lens group is composed of one positive lens and the back focus is sufficiently secured as compared with the focal length, it has not been achieved in miniaturization because of the long optical total length.

前記特許文献５に開示されているズームレンズは、少枚数構成で４群ズームレンズを達成している。第３群を正レンズ１枚で構成しており、焦点距離に比してバックフォーカスも十分確保されているものの、光学全長が長いため小型化においては達成できていなかった。 The zoom lens disclosed in Patent Document 5 achieves a four-group zoom lens with a small number of lenses. Although the third lens group is composed of one positive lens and the back focus is sufficiently secured as compared with the focal length, it has not been achieved in miniaturization because of the long optical total length.

前記特許文献６に開示されているズームレンズは、少枚数構成で４群ズームレンズを達成している。第３群を正レンズ１枚で構成しており、また、最終レンズにプラスチック非球面レンズを用いて高画質化が図られ、焦点距離に比してバックフォーカスも十分確保されているものの、光学全長が長いため小型化においては達成できていなかった。 The zoom lens disclosed in Patent Document 6 achieves a four-group zoom lens with a small number of lenses. The third lens unit is composed of a single positive lens, and the final lens uses a plastic aspheric lens to improve the image quality, and the back focus is sufficiently ensured compared to the focal length. Due to the long overall length, it could not be achieved in miniaturization.

本発明は、ズーミングに伴う各レンズ群の屈折力等を適切に設定することにより比較的バックフォーカスの長い高変倍比で全変倍範囲にわたり高い光学性能を有するズームレンズ及びそれを有する光学機器の提供を目的とする。 The present invention relates to a zoom lens having high optical performance over the entire zoom range at a high zoom ratio with a relatively long back focus by appropriately setting the refractive power of each lens group accompanying zooming, and an optical apparatus having the zoom lens The purpose is to provide.

物体側から順に、正の屈折力を有する第１群、負の屈折力を有する第２群、正の屈折力を有する第３群、正の屈折力を有する第４群より構成され、広角端から望遠端への変倍に際して、前記第１群と前記第２群の空気間隔が大きく、前記第２群と前記第３群の空気間隔が小さく、前記第３群と前記第４群の空気間隔が小さくなるように、前記第１群、前記第３群、前記第４群が物体側へ移動し、広角端におけるバックフォーカスをＳｋｗ、前記第３群の焦点距離をｆ３、前記第４群の焦点距離をｆ４、広角端における全系の焦点距離をｆｗとしたとき、
０．２＜ｆｗ／Ｓｋｗ＜０．６（１）
０．０１＜ｆｗ／ｆ３＜０．４（２）
１．３＜ｆ４／ｆｗ ≦ １．７８（７）
なる条件を満足することを特徴とするズームレンズ。 In order from the object side, a first lens unit having a positive refractive power, a second lens unit having negative refractive power, a third group having a positive refractive power, is composed of a fourth group having a positive refractive power, the wide-angle end during zooming to the telephoto end from the first group and the second group of the air gap is large, the air gap of the third group and the second group is small, the air of the third group and the fourth group as distance decreases, the first group, the third group, the fourth group is moved toward the object side, SKW back focus at the wide-angle end, the focal length of the third group f3, the fourth group Is the focal length of f4, and the focal length of the entire system at the wide-angle end is fw.
0.2 <fw / Skw <0.6 (1)
0.01 <fw / f3 <0.4 (2)
1.3 <f4 / fw ≦ 1.78 (7)
A zoom lens characterized by satisfying the following conditions:

全変倍範囲において高い光学性能を有した比較的バックフォーカスが長く、光学全長の短いズームレンズが実現可能である。 A zoom lens having a high optical performance in the entire zoom range, a relatively long back focus, and a short optical total length can be realized.

以下、本発明のズームレンズ及びそれを有する光学機器の実施形態について説明する。 Hereinafter, embodiments of a zoom lens and an optical apparatus having the same according to the present invention will be described.

図１は実施形態１のズームレンズの広角端のレンズ断面図、図２、図３は実施形態１のズームレンズの広角端、望遠端のズーム位置における収差図である。 FIG. 1 is a lens cross-sectional view at the wide-angle end of the zoom lens according to the first embodiment, and FIGS. 2 and 3 are aberration diagrams at the zoom position at the wide-angle end and the telephoto end of the zoom lens according to the first embodiment.

図４は実施形態２のズームレンズの広角端のレンズ断面図、図５、図６は実施形態２のズームレンズの広角端、望遠端のズーム位置における収差図である。 FIG. 4 is a lens cross-sectional view at the wide-angle end of the zoom lens according to the second embodiment, and FIGS. 5 and 6 are aberration diagrams at the zoom position at the wide-angle end and the telephoto end of the zoom lens according to the second embodiment.

図７は実施形態３のズームレンズの広角端のレンズ断面図、図８、図９は実施形態３のズームレンズの広角端、望遠端のズーム位置における収差図である。 FIG. 7 is a lens cross-sectional view at the wide-angle end of the zoom lens according to the third embodiment, and FIGS. 8 and 9 are aberration diagrams at the zoom position at the wide-angle end and the telephoto end of the zoom lens according to the third embodiment.

図１０は実施形態４のズームレンズの広角端のレンズ断面図、図１１、図１２は実施形態４のズームレンズの広角端、望遠端のズーム位置における収差図である。 FIG. 10 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 4, and FIGS. 11 and 12 are aberration diagrams at the zoom position at the wide-angle end and telephoto end of the zoom lens according to Embodiment 4.

図１３は実施形態５のズームレンズの広角端のレンズ断面図、図１４、図１５は実施形態５のズームレンズの広角端、望遠端のズーム位置における収差図である。 FIG. 13 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 5, and FIGS. 14 and 15 are aberration diagrams at the zoom position at the wide-angle end and telephoto end of the zoom lens according to Embodiment 5.

図１６は実施形態６のズームレンズの広角端のレンズ断面図、図１７、図１８は実施形態６のズームレンズの広角端、望遠端のズーム位置における収差図である。 FIG. 16 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 6, and FIGS. 17 and 18 are aberration diagrams at the zoom position at the wide-angle end and telephoto end of the zoom lens according to Embodiment 6.

図１、図４、図７、図１０、図１３、図１６のレンズ断面図において、Ｌ１は正の屈折力の第１レンズ群、Ｌ２は負の屈折力の第２レンズ群、Ｌ３は正の屈折力の第３レンズ群、Ｌ４は正の屈折力の第４レンズ群である。広角端に対して望遠端での、第１レンズ群Ｌ１と第２レンズ群Ｌ２の間隔（軸上空気間隔）が大きく、第２レンズ群Ｌ２と第３レンズ群Ｌ３の間隔が小さく、第３レンズ群Ｌ３と第４レンズ群Ｌ４の間隔が小さくなるようにレンズ群を矢印の如く物体側へ移動させてズーミングを行っている。 In the lens cross-sectional views of FIGS. 1, 4, 7, 10, 13, and 16, L1 is a first lens unit having a positive refractive power, L2 is a second lens unit having a negative refractive power, and L3 is a positive lens unit. The third lens group having a refractive power of L4 is a fourth lens group having a positive refractive power. The distance between the first lens group L1 and the second lens group L2 (axial air distance) at the telephoto end with respect to the wide-angle end is large, and the distance between the second lens group L2 and the third lens group L3 is small. Zooming is performed by moving the lens unit to the object side as indicated by an arrow so that the distance between the lens unit L3 and the fourth lens unit L4 is small.

具体的には、第１、第３、第４レンズ群Ｌ１、Ｌ３、Ｌ４を物体側へ、第２レンズ群Ｌ２を像面側に凸状の軌跡の一部に沿って移動させている。 Specifically, the first, third, and fourth lens groups L1, L3, and L4 are moved toward the object side, and the second lens group L2 is moved along a portion of the convex locus toward the image plane side.

ＳＰは絞りである。ＦＳはフレアーカット絞りであり、本実施例においては変倍の際、固定であるが、変倍で移動させても良い。ＩＰは像面であり、デジタルカメラのときは固体撮像素子がフィルム用カメラのときはフィルムが位置している。 SP is an aperture. FS is a flare cut stop. In this embodiment, it is fixed at the time of zooming, but may be moved by zooming. IP is an image plane. When a digital camera is used, a film is positioned when a solid-state image pickup device is a film camera.

フォーカスは第２レンズ群Ｌ２を光軸に沿って移動させて行っている。 Focusing is performed by moving the second lens unit L2 along the optical axis.

尚、各実施形態において、広角端と望遠端とは変倍用のレンズ群が機構上、移動可能な光軸上、一端から他端まで移動するときの両端のズーム位置をいう。 In each embodiment, the wide-angle end and the telephoto end refer to zoom positions at both ends when the lens unit for zooming moves from one end to the other end on the optical axis that can be moved mechanically.

収差図において、ｄはｄ線、ｇはｇ線、Ｓ．Ｃは正弦条件、ΔＭはメリディオナル像面、ΔＳはサジタル像面、倍率色収差はｇ線によって表わしている。また、ＦｎｏはＦナンバー、Ｙは像高である。 In the aberration diagrams, d is d-line, g is g-line, and S.P. C is a sine condition, ΔM is a meridional image plane, ΔS is a sagittal image plane, and lateral chromatic aberration is represented by a g-line. Fno is the F number and Y is the image height.

次に、実施形態１〜６のズームレンズのレンズ構成の特徴について説明する。 Next, features of the lens configuration of the zoom lenses of Embodiments 1 to 6 will be described.

実施形態１〜６に係るズームレンズは、４つのレンズ群を全て移動させてズーミング及び変倍に伴う像面変動の補正を行うことにより、屈折力の効率的な分配を行い、全体としてコンパクトな光学系ながらも高い変倍比と良好な光学性能を得ている。 The zoom lenses according to the first to sixth embodiments efficiently distribute the refractive power by moving all four lens groups and correcting the image plane variation accompanying zooming and zooming, and are compact as a whole. Although it is an optical system, it has a high zoom ratio and good optical performance.

第１群は正レンズ１枚と負レンズ１枚で構成することで、色収差を補正すると共に、特に望遠端における球面収差を補正することが出来る。２枚構成とすることで第１群を薄くできるのでメカ構成においても有利であり小型化に寄与する。 Group 1 by configuring it one by one positive lens and a negative lens, is corrected for chromatic aberration, can be particularly correct spherical aberration at the telephoto end. Since the first group can be made thinner by adopting the two-sheet configuration, it is advantageous in the mechanical configuration and contributes to downsizing.

第２群は負レンズ２枚と正レンズ１枚で構成している。第２群は、最も変倍分担が大きく、また、フォーカス群であるため第２群単独である程度の収差補正がなされていなければならない。第２群は負の屈折力が強いので負レンズ１枚、正レンズ１枚では収差補正が十分にできない為、負レンズを２枚に分けることで実現している。また、第２群の最も物体側のレンズを物体側へ凸の負メニスカスレンズとすることで特に広角端における歪曲収差を補正している。 The second group is composed of two negative lenses and one positive lens. The second group has the largest variable magnification share, and since it is a focus group, some aberration correction must be performed by the second group alone. Since the second lens group has a strong negative refractive power, the aberration correction cannot be sufficiently performed with one negative lens and one positive lens. Therefore, the second lens is realized by dividing the negative lens into two lenses. In addition, the lens on the most object side in the second group is a negative meniscus lens convex toward the object side, thereby correcting distortion particularly at the wide-angle end.

第３群は正レンズ１枚と負レンズ１枚、又は、正レンズ１枚のみで構成している。第３群の正の屈折力は第４群の正の屈折力より弱くなるような屈折力配置を設定しており、第３群は比較的少枚数で構成できる。正レンズ１枚構成とすることで第２群、第４群で発生する変倍における球面収差変動を補正することができるので好ましい。変倍率が高くなり変倍による軸上色収差変動が大きくなってきたり、更なる高性能化を図るためには正レンズと負レンズの２枚構成にすることが好ましい。 The third group consists of one positive lens and one negative lens, or only one positive lens. The refractive power arrangement is set such that the positive refractive power of the third group is weaker than the positive refractive power of the fourth group, and the third group can be configured with a relatively small number of lenses. It is preferable to use a single positive lens configuration because it is possible to correct spherical aberration fluctuations in zooming occurring in the second group and the fourth group. In order to increase the magnification and the axial chromatic aberration fluctuation due to the magnification change, or to further improve the performance, it is preferable to use a positive lens and a negative lens.

第４群は正レンズと負レンズとプラスチック非球面レンズで構成している。第４群は広角端から望遠端への変倍において物体側へ大きく移動しており、軸外光束の４群通過位置が広角端と望遠端で比較的異なっているので、第４群の中でも、より像面側の位置に非球面を配置することで全変倍範囲にわたり高い光学性能が実現できる。プラスチックはガラスと比べて温度による膨張収縮や屈折率変化が大きいので、プラスチック非球面レンズの屈折力を弱く設定することが好ましい。 The fourth group includes a positive lens, a negative lens, and a plastic aspheric lens. The fourth group has moved greatly to the object side during zooming from the wide-angle end to the telephoto end, and the position where the off-axis light beam passes through the fourth group is relatively different between the wide-angle end and the telephoto end. By arranging an aspheric surface at a position closer to the image plane side, high optical performance can be realized over the entire zoom range. Since plastic has a larger expansion / contraction and refractive index change due to temperature than glass, it is preferable to set the refractive power of the plastic aspheric lens weak.

次に、本発明のズームレンズが満足する条件式または満足することが望ましい条件式である条件式（１）−（５）について説明する。Next, conditional expressions (1) to (5) that are conditional expressions that the zoom lens of the present invention satisfies or conditional expressions that should be satisfied will be described.
０．２＜ｆｗ／Ｓｋｗ＜０．６0.2 <fw / Skw <0.6 （１）(1)
０．０１＜ｆｗ／ｆ３＜０．４0.01 <fw / f3 <0.4 （２）(2)
０．５＜ｆｗ／Ｄｐｗ＜０．７0.5 <fw / Dpw <0.7 （３）(3)
０．４＜Ｓｋｗ／ＴＤｗ＜０．８0.4 <Skw / TDw <0.8 （４）(4)
−３．０＜ｍ４／ｆｗ＜ −０．４−3.0 <m4 / fw <−0.4 （５）(5)

条件式（１）は広角端におけるバックフォーカスと広角端における全系の焦点距離の比に関し、小型化と適切なバックフォーカスを設定するためのものである。但し、バックフォーカスとは最も像面側のレンズ面の面頂点から無限物点に対する近軸像面までの距離である。 Conditional expression (1) relates to the ratio between the back focus at the wide-angle end and the focal length of the entire system at the wide-angle end, in order to reduce the size and set an appropriate back focus. However, the back focus is the distance from the surface vertex of the lens surface closest to the image plane to the paraxial image plane with respect to the infinite object point.

条件式（１）の下限値を超えると、焦点距離に対してバックフォーカスが長くなり過ぎて、全系の全長が長くなり、前玉径も増大傾向があるので小型化を図る上で良くない。条件式（１）の上限値を超えると、バックフォーカスが短くなり過ぎて一眼レフのミラー等と干渉するなど、メカ構成上良くない。更に好ましくは、条件式（１）の下限値を０．４２とすることが望ましい。 If the lower limit value of conditional expression (1) is exceeded, the back focus becomes too long with respect to the focal length, the total length of the entire system becomes long, and the front lens diameter tends to increase, which is not good for downsizing. . If the upper limit value of conditional expression (1) is exceeded, the back focus becomes too short and interferes with a single-lens reflex mirror or the like, which is not good in terms of mechanical configuration. More preferably, it is desirable to set the lower limit value of conditional expression (1) to 0.42.

条件式（２）は第３群の焦点距離と広角端における全系の焦点距離との比であり、第３群の焦点距離を適切に設定することで第３群の少枚数化を達成しつつ高い光学性能を得ることができる。 Conditional expression (2) is the ratio of the focal length of the third group to the focal length of the entire system at the wide-angle end, and the number of the third group can be reduced by appropriately setting the focal length of the third group. High optical performance can be obtained.

条件式（２）の下限値を超えると第３群の屈折力が弱くなり過ぎて第２群または第４群で発生する変倍における球面収差変動を抑制することが困難となり、補正しようとすると第３群の移動量が増大してレンズ系全体が大型化するので良くない。また、上限値を超えて第３群の屈折力が強くなり過ぎると、広角端において全系の像側主点位置が物体側へ位置するようになりバックフォーカスを確保することが困難となるので良くない。また、バックフォーカスを確保しようとして第４群の屈折力を弱くすると第３群の変倍分担が大きくなり、第３群を少枚数で構成することが困難となるため良くない。 If the lower limit value of conditional expression (2) is exceeded, the refractive power of the third group becomes too weak to make it difficult to suppress the spherical aberration fluctuations in zooming occurring in the second group or the fourth group. This is not good because the movement amount of the third lens unit increases and the entire lens system becomes large. Further, if the refractive power of the third group becomes too strong beyond the upper limit value, the image-side principal point position of the entire system will be located on the object side at the wide-angle end, and it will be difficult to ensure back focus. Not good. In addition, if the refractive power of the fourth group is weakened in order to secure the back focus, the variable power sharing of the third group becomes large, and it is difficult to configure the third group with a small number of sheets.

更に好ましくは条件式（２）の下限値を０．０６とすることが望ましい。また、上限値を０．２９とすることが望ましい。 More preferably, the lower limit value of conditional expression (2) is 0.06. Moreover, it is desirable that the upper limit value be 0.29.

条件式（３）は開放絞りと最も像面側のレンズ面頂点との広角端における距離と広角端における全系の焦点距離の比に関し、小型化と色収差を良好に補正するためのものである。条件式（３）の下限値を超えると射出瞳位置が物体側に寄り過ぎて後玉径が増大すると共に広角端における倍率色収差の補正が困難となるので良くない。また、上限を超えると入射瞳位置が像面側に寄り過ぎて前玉径が増大すると共に望遠端における倍率色収差の補正が困難となるので良くない。 Conditional expression (3) relates to the ratio between the wide-angle end distance between the wide-angle end and the focal length of the entire system at the wide- angle end between the wide-angle end and the lens surface apex closest to the image plane, and is used to satisfactorily correct the size reduction and chromatic aberration. . If the lower limit of conditional expression (3) is exceeded, the exit pupil position will be too close to the object side, the rear lens diameter will increase, and it will be difficult to correct lateral chromatic aberration at the wide angle end. If the upper limit is exceeded, the entrance pupil position is too close to the image plane side, the front lens diameter increases, and it becomes difficult to correct lateral chromatic aberration at the telephoto end.

条件式（４）は、広角端におけるバックフォーカスと広角端におけるレンズ第1面から最終レンズ面までの距離との比に関し、小型化と諸収差のバランスを図るためのものである。 Conditional expression (4) relates to the ratio between the back focus at the wide-angle end and the distance from the first lens surface to the final lens surface at the wide-angle end in order to balance the reduction in size and various aberrations.

条件式（４）の下限値を超えるとレンズ全長が長くなり、レンズ径も増大するので良くない。また、上限値を超えると各群の屈折力が強くなる傾向にあり、少枚数なレンズ構成では諸収差を補正することが困難となるので良くない。 If the lower limit of conditional expression (4) is exceeded, the total lens length becomes longer and the lens diameter increases, which is not good. If the upper limit is exceeded, the refractive power of each group tends to increase, and it is difficult to correct various aberrations with a small number of lenses.

更に好ましくは、条件式（４）の上限値を０．６とすることが望ましい。 More preferably, it is desirable to set the upper limit of conditional expression (4) to 0.6.

条件式（５）は、前記第４群の広角端から望遠端への変倍における移動量と広角端における全系の焦点距離との比に関し、主に変倍における収差変動を補正するためのものである。 Conditional expression (5) relates to the ratio of the amount of movement in zooming from the wide-angle end to the telephoto end of the fourth group and the focal length of the entire system at the wide-angle end. Is.

条件式（５）の下限値を超えると前記第４群の移動量が大きくなり過ぎて望遠端における光学全長が増大するので良くない。また、上限値を超えると第４群の変倍作用が減少して変倍比を確保することが困難となり、また、第４群を通過する軸外光束の光軸からの距離が広角端と望遠端とで差が小さくなるので、変倍における軸外の収差補正に不利となり、変倍における収差変動が悪化するので良くない。 If the lower limit of conditional expression (5) is exceeded, the amount of movement of the fourth group becomes too large, and the total optical length at the telephoto end increases, which is not good. If the upper limit is exceeded, the zooming action of the fourth group decreases, making it difficult to ensure the zoom ratio, and the distance from the optical axis of the off-axis light beam passing through the fourth group is at the wide-angle end. Since the difference between the telephoto end is small, it is disadvantageous for off-axis aberration correction at zooming, and aberration fluctuation at zooming is deteriorated.

更に好ましくは、条件式（５）の下限値を−２．０とすることが望ましい。また、上限値を−１．１とすることが望ましい。 More preferably, the lower limit of the condition (5) -2.0 and the child is desired. Moreover, it is desirable that the upper limit value be −1.1.

更に好ましくは、以下の（Ａ）〜（Ｆ）の内少なくとも一つを満足させることが望ましい。 More preferably, it is desirable to satisfy at least one of the following (A) to (F).

（Ａ）
前記第２群を光軸方向に移動させることにより無限遠から至近までのフォーカシングを行い、前記第２群の焦点距離をｆ２、広角端における全系の焦点距離をｆｗとしたとき、
−１．０＜ｆ２／ｆｗ＜ −０．５（６）
なる条件を満足すること。 (A)
When the second group is moved in the optical axis direction to perform focusing from infinity to the nearest, the focal length of the second group is f2, and the focal length of the entire system at the wide angle end is fw.
−1.0 <f2 / fw <−0.5 (6)
Satisfy the following conditions .

（Ｂ）
前記第４群の焦点距離をｆ４、広角端における全系の焦点距離をｆｗとしたとき、
１．３＜ｆ４／ｆｗ ≦ １．７８（７）
なる条件を満足すること。 (B)
When the focal length of the fourth group is f4 and the focal length of the entire system at the wide angle end is fw,
1.3 <f4 / fw ≦ 1.78 (7)
Satisfy the following conditions .

（Ｃ）
前記第１群の焦点距離をｆ１、広角端における全系の焦点距離をｆｗとしたとき、
０．１＜ｆｗ／ｆ１＜０．３（８）
なる条件を満足すること。 (C)
When the focal length of the first group is f1, and the focal length of the entire system at the wide angle end is fw,
0.1 <fw / f1 <0.3 (8)
Satisfy the following conditions .

（Ｄ）
前記第４群の最も像側にプラスチック非球面レンズを有し、該プラスチック非球面レンズの材質のアッベ数をＶｄとしたとき、
Ｖｄ＞５０（９）
なる条件を満足すること。 (D)
When a plastic aspherical lens is provided on the most image side of the fourth group, and the Abbe number of the material of the plastic aspherical lens is Vd,
Vd> 50 (9)
Satisfy the following conditions .

（Ｅ）
前記第４群は物体側から順に正レンズ、負レンズ、プラスチックレンズを有すること。 (E)
The fourth group includes a positive lens, a negative lens, and a plastic lens in order from the object side .

（Ｆ）
前記第１群は正レンズ１枚、負レンズ１枚から成ること。 (F)
The first group consists of one positive lens and one negative lens .

次に上述した（A）〜（ｆ）の技術的意味について説明する。 Next, the technical meaning of (A) to (f) will be described.

（A）
比較的強い負の屈折力を有する第２群を無限遠から至近の被写体に対して物体側へ繰出すことにより合焦させるようにしている。屈折力が比較的強いので繰出量が少なくて済むのでメカ機構上好ましく、また、フォーカシングによる収差変動を抑えることが出来るので好ましい。更に条件式（６）を満足するようにしている。 (A)
The second group having a relatively strong negative refractive power is focused on the object side from an infinite distance to the closest object. Since the refractive power is relatively strong, the amount of feeding is small, which is preferable in terms of the mechanical mechanism, and it is preferable because aberration fluctuations due to focusing can be suppressed. Further, conditional expression (6) is satisfied.

条件式（６）は、第２群の焦点距離と広角端における全系の焦点距離の比に関し、小型化と高性能化とのバランスが図られた第2群の屈折力を規定するものである。 Conditional expression (6) specifies the refractive power of the second group, which is a balance between miniaturization and high performance, regarding the ratio of the focal length of the second group to the focal length of the entire system at the wide-angle end. is there.

条件式（６）の下限値を超えると、第２群の屈折力が弱くなり過ぎてフォーカシングによる第２群の繰出量が増大し、第１群のレンズ径が大型化し、また、広角端においてバックフォーカスの確保が困難となるので好ましくない。また、上限値を超えると第２群の屈折力が強くなり過ぎてフォーカシングによる球面収差変動が大きくなり、また、特に広角端における歪曲収差を補正することが困難となるので好ましくない。 When the lower limit of conditional expression (6) is exceeded, the refractive power of the second group becomes too weak, the amount of extension of the second group by focusing increases, the lens diameter of the first group increases, and at the wide angle end. It is not preferable because it is difficult to ensure the back focus. If the upper limit is exceeded, the refractive power of the second group becomes too strong, and spherical aberration fluctuations due to focusing become large, and it becomes difficult to correct distortion especially at the wide-angle end, which is not preferable.

更に好ましくは、条件式（６）の上限値を−０．７５とすることが望ましい。 More preferably, it is desirable to set the upper limit value of conditional expression (6) to -0.75.

（B）
条件式（７）を満足するようにしている。 (B)
Conditional expression (7) is satisfied.

条件式（７）は第4群の焦点距離と広角端における全系の焦点距離の比に関し、広角端においてバックフォーカスを確保しつつ高性能化を図るためのものである。 Conditional expression (7) relates to the ratio of the focal length of the fourth lens unit to the focal length of the entire system at the wide-angle end, and is intended to improve performance while ensuring back focus at the wide-angle end.

条件式（７）の下限値を超えると、第４群の屈折力が強くなり過ぎて、特に広角端において像面湾曲が増大し、また、望遠端において球面収差を補正することが困難となるので好ましくない。また、上限値を超えると第４群の屈折力が弱くなり過ぎて、特に広角端においてレトロフォーカスタイプが弱くなり、バックフォーカスの確保が困難となるので好ましくない。 If the lower limit of Condition (7), too strong refractive power of the fourth group, in particular curvature increases at the wide-angle end, also, it becomes difficult to correct spherical aberration at the telephoto end Therefore, it is not preferable. If the upper limit is exceeded, the refractive power of the fourth group becomes too weak, and the retrofocus type becomes particularly weak at the wide-angle end, making it difficult to secure the back focus, which is not preferable.

（C）
条件式（８）を満足するようにしている。 (C)
Conditional expression (8) is satisfied.

条件式（８）は、第１群の焦点距離と広角端における全系の焦点距離の比に関し、小型化と光学性能のバランスを図るためのものである。 Conditional expression (8) relates to the ratio between the focal length of the first lens unit and the focal length of the entire system at the wide-angle end in order to achieve a balance between miniaturization and optical performance.

条件式（８）の下限値を越えて第１群の屈折力が強くなると、変倍時に発生する収差の補正が困難となるので好ましくない。また、上限値を越えて第１群の屈折力が弱くなると、変倍に際し第１レンズ群の移動量が大きく必要となり光学系の小型化が困難となるので好ましくない。 If the lower limit of conditional expression (8) is exceeded and the refractive power of the first group becomes strong, it will be difficult to correct aberrations that occur during zooming. Further, if the refractive power of the first group becomes weaker than the upper limit value, it is not preferable because a large amount of movement of the first lens group is required at the time of zooming and it becomes difficult to downsize the optical system.

更に好ましくは、条件式（８）の下限値を０．１５とすることが望ましい。また、上限値を０．２５とすることが望ましい。 More preferably, it is desirable to set the lower limit of conditional expression (8) to 0.15. Moreover, it is desirable that the upper limit value be 0.25.

（D）
前記第４群の最も像側にプラスチック非球面レンズを配置している。最も像面側に中心から周辺にかけて正の屈折力が弱くなる非球面を配置することで特に広角端における歪曲収差とコマ収差を良好に補正できる。プラスチックとは有機材料であり、ガラス非球面レンズと比べ低価格であるので好ましい。 (D)
A plastic aspheric lens is disposed closest to the image side of the fourth group. By disposing an aspherical surface in which the positive refractive power is weakened from the center to the periphery on the most image side, distortion and coma particularly at the wide-angle end can be corrected well. Plastic is an organic material and is preferable because it is less expensive than a glass aspheric lens.

更に条件式（９）を満足するようにしている。 Further, conditional expression (9) is satisfied.

条件式（９）は前記第4群の最も像側にプラスチック非球面レンズの材質のアッベ数を規定したものであり、特に広角端における軸外の諸収差を良好に補正するためのものである。 Conditional expression (9) defines the Abbe number of the material of the plastic aspherical lens on the most image side of the fourth group, and particularly for correcting various off-axis aberrations at the wide-angle end. .

条件式（９）の下限値を超えてプラスチックの材質の分散が強くなると特に広角端において色のコマ収差が発生し光学性能が悪化するので好ましくない。 If the lower limit of conditional expression (9) is exceeded and the dispersion of the plastic material becomes strong, color coma occurs particularly at the wide-angle end, and the optical performance deteriorates.

（F）
前記第１群を正レンズ１枚、負レンズ１枚の２枚構成にすることで第１群が薄くできるので光学系の小型化が図られるので好ましい。光学系の中で第１群はレンズ径が最も大きく、第１群が厚くなるとメカ機構で使える空間がなくなり、その為、広角端における光学全長を大きくしなければならず、小型化において不利になる。 (F)
It is preferable that the first group is composed of one positive lens and one negative lens so that the first group can be made thin, so that the optical system can be miniaturized. In the optical system, the first lens unit has the largest lens diameter, and when the first lens unit becomes thick, there is no space that can be used by the mechanical mechanism. Therefore, the optical total length at the wide angle end must be increased, which is disadvantageous in miniaturization. Become.

次に本発明の数値実施例を示す。数値実施例においてＲｉは物体側より順に第ｉ番目のレンズ面の曲率半径、Ｄｉはそれぞれ第ｉ番目のレンズ厚または空気間隔、ＮｉとＶｉは第ｉ番目のレンズの材質の屈折率とアッベ数である。また、非球面形状はレンズ面の中心部の曲率半径をＲとし、光軸方向２をＸ軸とし、光軸と垂直方向をＹ軸とし、A，Ｂ，Ｃ、Ｄ，Ｅ、Ｆをそれぞれ非球面係数としたとき、 Next, numerical examples of the present invention will be shown. In the numerical example, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness or air spacing, Ni and Vi are the refractive index and Abbe number of the material of the i-th lens, respectively. It is. The aspherical shape has a radius of curvature at the center of the lens surface as R, the optical axis direction 2 as the X axis, the optical axis and the vertical direction as the Y axis, and A, B, C, D, E, and F respectively. When the aspheric coefficient is used,

表１には本発明の上述した条件式と数値実施例の関係を示す。

Table 1 shows the relationship between the above-described conditional expressions of the present invention and numerical examples.

数値実施例 1
ｆ＝ 17.55〜 63.09 Ｆｎｏ＝ 3.49 〜 5.85 ２ω＝75.7 〜 24.4
R 1 = 54.758 D 1 = 7.02 N 1 = 1.712995 ν 1 = 53.9
R 2 = -200.914 D 2 = 1.80 N 2 = 1.846660 ν 2 = 23.9
R 3 = 523.721 D 3 = 可変
R 4 = 79.514 D 4 = 1.40 N 3 = 1.810890 ν 3 = 46.1
R 5 = 11.529 D 5 = 5.89
R 6 = -57.038 D 6 = 1.10 N 4 = 1.803567 ν 4 = 46.3
R 7 = 22.885 D 7 = 0.12
R 8 = 18.886 D 8 = 3.80 N 5 = 1.846660 ν 5 = 23.9
R 9 = 14237.822 D 9 = 可変
R10 = 絞り D10 = 2.17
R11 = 87.751 D11 = 1.83 N 6 = 1.514397 ν 6 = 54.7
R12 = -50.265 D12 = 0.10
R13 = -41.544 D13 = 1.00 N 7 = 1.779728 ν 7 = 28.7
R14 = -71.511 D14 = 可変
R15 = 13.281 D15 = 4.43 N 8 = 1.490409 ν 8 = 68.0
R16 = -54.778 D16 = 1.00 N 9 = 1.816219 ν 9 = 25.1
R17 = 96.026 D17 = 6.26
R18 = 77.246 D18 = 1.70 N10 = 1.491710 ν10 = 57.4
* R19 = -107.661 D19 = 可変
R20 = ∞
非球面係数
19面 : ｋ=0.00000e+00 Ａ=０Ｂ=9.28474e-05 Ｃ=3.48870e-07
Ｄ=2.69552e-09 E=2.97320e-11 F=0.00000e+00
＼焦点距離 17.55 31.50 63.09
可変間隔＼
D 3 2.54 15.14 26.44
D 9 17.79 10.29 3.32
D14 11.13 4.49 0.59
D19 0.75 9.83 26.99
数値実施例 2
ｆ＝ 17.55〜 63.10 Ｆｎｏ＝ 3.55 〜 5.85 ２ω＝75.7 〜 24.4
R 1 = 52.091 D 1 = 1.80 N 1 = 1.846660 ν 1 = 23.9
R 2 = 36.478 D 2 = 7.00 N 2 = 1.712995 ν 2 = 53.9
R 3 = 391.270 D 3 = 可変
R 4 = 78.974 D 4 = 1.40 N 3 = 1.804000 ν 3 = 46.6
R 5 = 11.397 D 5 = 5.86
R 6 = -64.049 D 6 = 1.10 N 4 = 1.772499 ν 4 = 49.6
R 7 = 22.061 D 7 = 0.12
R 8 = 18.264 D 8 = 3.70 N 5 = 1.846660 ν 5 = 23.9
R 9 = 275.874 D 9 = 可変
R10 = 絞り D10 = 3.95
R11 = 47.074 D11 = 1.88 N 6 = 1.516330 ν 6 = 64.1
R12 = -36.496 D12 = 0.32
R13 = -33.907 D13 = 1.00 N 7 = 1.834000 ν 7 = 37.2
R14 = -178.862 D14 = 可変
R15 = 13.805 D15 = 4.48 N 8 = 1.487490 ν 8 = 70.2
R16 = -42.980 D16 = 1.00 N 9 = 1.846660 ν 9 = 23.9
R17 = -238.566 D17 = 5.94
R18 = 499.134 D18 = 1.70 N10 = 1.491710 ν10 = 57.4
* R19 = -102.686 D19 = 可変
R20 = ∞
非球面係数
19面 : ｋ=0.00000e+00 Ａ=０Ｂ=1.06618e-04 Ｃ=1.74946e-07
Ｄ=1.00252e-08 E=-3.70645e-11 F=0.00000e+00
＼焦点距離 17.55 32.65 63.10
可変間隔＼
D 3 2.60 13.08 25.52
D 9 17.85 8.52 2.31
D14 7.35 3.09 0.60
D19 0.69 12.20 28.06
数値実施例 3
ｆ＝ 18.55〜 63.78 Ｆｎｏ＝ 3.83 〜 5.85 ２ω＝72.6 〜 24.1
R 1 = 71.459 D 1 = 6.89 N 1 = 1.696797 ν 1 = 55.5
R 2 = -125.465 D 2 = 1.80 N 2 = 1.846660 ν 2 = 23.9
R 3 = -878.861 D 3 = 可変
R 4 = 124.555 D 4 = 1.40 N 3 = 1.712995 ν 3 = 53.9
R 5 = 12.183 D 5 = 6.20
R 6 = -72.585 D 6 = 1.10 N 4 = 1.712995 ν 4 = 53.9
R 7 = 24.427 D 7 = 0.12
R 8 = 19.400 D 8 = 3.70 N 5 = 1.805181 ν 5 = 25.4
R 9 = 151.868 D 9 = 可変
R10 = 絞り D10 = 4.43
R11 = 38.666 D11 = 1.55 N 6 = 1.487490 ν 6 = 70.2
R12 = -227.781 D12 = 0.30
R13 = -96.461 D13 = 1.00 N 7 = 1.846660 ν 7 = 23.9
R14 = -676.468 D14 = 可変
R15 = 13.420 D15 = 5.03 N 8 = 1.487490 ν 8 = 70.2
R16 = -47.196 D16 = 1.00 N 9 = 1.846660 ν 9 = 23.9
R17 = -332.590 D17 = 5.70
R18 = -107.598 D18 = 1.50 N10 = 1.491710 ν10 = 57.4
* R19 = -117.977 D19 = 可変
R20 = ∞
非球面係数
19面 : ｋ=0.00000e+00 Ａ=０Ｂ=1.20151e-04 Ｃ=3.89639e-07
Ｄ=6.75416e-09 E=8.91048e-12 F=0.00000e+00
＼焦点距離 18.55 31.47 63.78
可変間隔＼
D 3 2.99 15.69 30.86
D 9 20.72 11.28 2.61
D14 7.23 3.99 1.42
D19 0.49 8.88 24.55
数値実施例 4
ｆ＝ 17.57〜 63.10 Ｆｎｏ＝ 3.47 〜 5.85 ２ω＝75.6 〜 24.4
R 1 = 60.219 D 1 = 6.97 N 1 = 1.696797 ν 1 = 55.5
R 2 = -175.009 D 2 = 1.80 N 2 = 1.846660 ν 2 = 23.9
R 3 = 1970.686 D 3 = 可変
R 4 = 85.053 D 4 = 1.40 N 3 = 1.804000 ν 3 = 46.6
R 5 = 11.644 D 5 = 6.16
R 6 = -56.088 D 6 = 1.10 N 4 = 1.772499 ν 4 = 49.6
R 7 = 24.731 D 7 = 0.12
R 8 = 19.514 D 8 = 3.50 N 5 = 1.805181 ν 5 = 25.4
R 9 = 2320.747 D 9 = 可変
R10 = 絞り D10 = 0.80
R11 = 103.870 D11 = 1.74 N 6 = 1.487490 ν 6 = 70.2
R12 = -150.610 D12 = 可変
R13 = 13.378 D13 = 5.26 N 7 = 1.487490 ν 7 = 70.2
R14 = -40.270 D14 = 1.00 N 8 = 1.846660 ν 8 = 23.9
R15 = 433.972 D15 = 5.94
R16 = 156.798 D16 = 1.70 N 9 = 1.491710 ν 9 = 57.4
* R17 = -111.139 D17 = 可変
R18 = ∞
非球面係数
17面 : ｋ=0.00000e+00 Ａ=０Ｂ=9.94868e-05 Ｃ=1.49969e-07
Ｄ=1.02746e-08 E=-3.81624e-11 F=0.00000e+00
＼焦点距離 17.57 31.00 63.10
可変間隔＼
D 3 2.55 15.08 26.60
D 9 18.37 11.28 5.28
D12 13.51 6.68 0.82
D17 0.47 9.72 28.38 数値実施例 5
ｆ＝ 18.55〜 63.09 Ｆｎｏ＝ 3.53 〜 5.85 ２ω＝72.6 〜 24.4
R 1 = 58.655 D 1 = 6.80 N 1 = 1.696797 ν 1 = 55.5
R 2 = -173.610 D 2 = 1.80 N 2 = 1.846660 ν 2 = 23.9
R 3 = 1129.100 D 3 = 可変
R 4 = 91.613 D 4 = 1.40 N 3 = 1.670029 ν 3 = 47.2
R 5 = 11.308 D 5 = 6.38
R 6 = -67.146 D 6 = 1.10 N 4 = 1.772499 ν 4 = 49.6
R 7 = 23.445 D 7 = 0.12
R 8 = 18.790 D 8 = 3.60 N 5 = 1.846660 ν 5 = 23.9
R 9 = 108.872 D 9 = 可変
R10 = 絞り D10 = 2.73
R11 = 53.514 D11 = 2.00 N 6 = 1.487490 ν 6 = 70.2
R12 = 348.077 D12 = 可変
R13 = 13.877 D13 = 5.67 N 7 = 1.487490 ν 7 = 70.2
R14 = -43.755 D14 = 1.00 N 8 = 1.846660 ν 8 = 23.9
R15 = 193.468 D15 = 5.37
R16 = 96.043 D16 = 1.90 N 9 = 1.491710 ν 9 = 57.4
* R17 = -72.083 D17 = 可変
R18 = ∞
非球面係数
17面 : ｋ=0.00000e+00 Ａ=０Ｂ=8.58802e-05 Ｃ=2.76497e-07
Ｄ=2.61371e-09 E=1.55605e-11 F=0.00000e+00
＼焦点距離 18.55 28.22 63.09
可変間隔＼
D 3 2.82 11.55 26.05
D 9 16.86 10.62 2.75
D12 10.86 6.60 1.03
D17 0.85 7.62 26.56
数値実施例 6
ｆ＝ 20.00〜 78.02 Ｆｎｏ＝ 3.47 〜 5.85 ２ω＝68.5 〜 19.8
R 1 = 58.092 D 1 = 6.50 N 1 = 1.712995 ν 1 = 53.9
R 2 = -195.337 D 2 = 1.80 N 2 = 1.846660 ν 2 = 23.9
R 3 = 613.798 D 3 = 可変
R 4 = 128.035 D 4 = 1.50 N 3 = 1.670029 ν 3 = 47.2
R 5 = 12.300 D 5 = 5.97
R 6 = -74.458 D 6 = 1.00 N 4 = 1.772499 ν 4 = 49.6
R 7 = 25.250 D 7 = 0.12 R 8 = 19.883 D 8 = 3.20 N 5 = 1.846660 ν 5 = 23.9
R 9 = 77.032 D 9 = 可変
R10 = 絞り D10 = 1.15
* R11 = 35.937 D11 = 2.20 N 6 = 1.491710 ν 6 = 57.4
R12 = 558.742 D12 = 可変
R13 = 14.402 D13 = 5.28 N 7 = 1.487490 ν 7 = 70.2
R14 = -45.390 D14 = 1.00 N 8 = 1.846660 ν 8 = 23.9
R15 = 215.130 D15 = 6.01
R16 = 256.239 D16 = 2.30 N 9 = 1.524700 ν 9 = 56.2
* R17 = -78.926 D17 = 可変
R18 = ∞
非球面係数
11面 : Ａ=0.00000e+00 Ｂ=-2.19327e-06 Ｃ=1.39344e-08
Ｄ=0.00000e+00 E=0.00000e+00 F=0.00000e+00
17面 : ｋ=0.00000e+00 Ａ=０Ｂ=7.69941e-05 Ｃ=8.46426e-08
Ｄ=7.32963e-09 E=-4.13547e-11 F=0.00000e+00
＼焦点距離 20.00 31.30 78.02
可変間隔＼
D 3 3.22 13.34 31.01
D 9 17.79 11.26 2.77
D12 12.63 7.68 1.16
D17 0.00 7.23 27.99 Numerical example 1
f = 17.55 to 63.09 Fno = 3.49 to 5.85 2ω = 75.7 to 24.4
R 1 = 54.758 D 1 = 7.02 N 1 = 1.712995 ν 1 = 53.9
R 2 = -200.914 D 2 = 1.80 N 2 = 1.846660 ν 2 = 23.9
R 3 = 523.721 D 3 = variable
R 4 = 79.514 D 4 = 1.40 N 3 = 1.810890 ν 3 = 46.1
R 5 = 11.529 D 5 = 5.89
R 6 = -57.038 D 6 = 1.10 N 4 = 1.803567 ν 4 = 46.3
R 7 = 22.885 D 7 = 0.12
R 8 = 18.886 D 8 = 3.80 N 5 = 1.846660 ν 5 = 23.9
R 9 = 14237.822 D 9 = Variable
R10 = Aperture D10 = 2.17
R11 = 87.751 D11 = 1.83 N 6 = 1.514397 ν 6 = 54.7
R12 = -50.265 D12 = 0.10
R13 = -41.544 D13 = 1.00 N 7 = 1.779728 ν 7 = 28.7
R14 = -71.511 D14 = variable
R15 = 13.281 D15 = 4.43 N 8 = 1.490409 ν 8 = 68.0
R16 = -54.778 D16 = 1.00 N 9 = 1.816219 ν 9 = 25.1
R17 = 96.026 D17 = 6.26
R18 = 77.246 D18 = 1.70 N10 = 1.491710 ν10 = 57.4
* R19 = -107.661 D19 = variable
R20 = ∞
Aspheric coefficient
19th plane: k = 0.00000e + 00 A = 0 B = 9.28474e-05 C = 3.48870e-07
D = 2.69552e-09 E = 2.97320e-11 F = 0.00000e + 00
\ Focal length 17.55 31.50 63.09
Variable interval \
D 3 2.54 15.14 26.44
D 9 17.79 10.29 3.32
D14 11.13 4.49 0.59
D19 0.75 9.83 26.99
Numerical example 2
f = 17.55 to 63.10 Fno = 3.55 to 5.85 2ω = 75.7 to 24.4
R 1 = 52.091 D 1 = 1.80 N 1 = 1.846660 ν 1 = 23.9
R 2 = 36.478 D 2 = 7.00 N 2 = 1.712995 ν 2 = 53.9
R 3 = 391.270 D 3 = Variable
R 4 = 78.974 D 4 = 1.40 N 3 = 1.804000 ν 3 = 46.6
R 5 = 11.397 D 5 = 5.86
R 6 = -64.049 D 6 = 1.10 N 4 = 1.772499 ν 4 = 49.6
R 7 = 22.061 D 7 = 0.12
R 8 = 18.264 D 8 = 3.70 N 5 = 1.846660 ν 5 = 23.9
R 9 = 275.874 D 9 = variable
R10 = Aperture D10 = 3.95
R11 = 47.074 D11 = 1.88 N 6 = 1.516330 ν 6 = 64.1
R12 = -36.496 D12 = 0.32
R13 = -33.907 D13 = 1.00 N 7 = 1.834000 ν 7 = 37.2
R14 = -178.862 D14 = variable
R15 = 13.805 D15 = 4.48 N 8 = 1.487490 ν 8 = 70.2
R16 = -42.980 D16 = 1.00 N 9 = 1.846660 ν 9 = 23.9
R17 = -238.566 D17 = 5.94
R18 = 499.134 D18 = 1.70 N10 = 1.491710 ν10 = 57.4
* R19 = -102.686 D19 = variable
R20 = ∞
Aspheric coefficient
19th: k = 0.00000e + 00 A = 0 B = 1.06618e-04 C = 1.74946e-07
D = 1.00252e-08 E = -3.70645e-11 F = 0.00000e + 00
\ Focal length 17.55 32.65 63.10
Variable interval \
D 3 2.60 13.08 25.52
D 9 17.85 8.52 2.31
D14 7.35 3.09 0.60
D19 0.69 12.20 28.06
Numerical example 3
f = 18.55 to 63.78 Fno = 3.83 to 5.85 2ω = 72.6 to 24.1
R 1 = 71.459 D 1 = 6.89 N 1 = 1.696797 ν 1 = 55.5
R 2 = -125.465 D 2 = 1.80 N 2 = 1.846660 ν 2 = 23.9
R 3 = -878.861 D 3 = variable
R 4 = 124.555 D 4 = 1.40 N 3 = 1.712995 ν 3 = 53.9
R 5 = 12.183 D 5 = 6.20
R 6 = -72.585 D 6 = 1.10 N 4 = 1.712995 ν 4 = 53.9
R 7 = 24.427 D 7 = 0.12
R 8 = 19.400 D 8 = 3.70 N 5 = 1.805181 ν 5 = 25.4
R 9 = 151.868 D 9 = Variable
R10 = Aperture D10 = 4.43
R11 = 38.666 D11 = 1.55 N 6 = 1.487490 ν 6 = 70.2
R12 = -227.781 D12 = 0.30
R13 = -96.461 D13 = 1.00 N 7 = 1.846660 ν 7 = 23.9
R14 = -676.468 D14 = variable
R15 = 13.420 D15 = 5.03 N 8 = 1.487490 ν 8 = 70.2
R16 = -47.196 D16 = 1.00 N 9 = 1.846660 ν 9 = 23.9
R17 = -332.590 D17 = 5.70
R18 = -107.598 D18 = 1.50 N10 = 1.491710 ν10 = 57.4
* R19 = -117.977 D19 = variable
R20 = ∞
Aspheric coefficient
19th: k = 0.00000e + 00 A = 0 B = 1.20151e-04 C = 3.89639e-07
D = 6.75416e-09 E = 8.91048e-12 F = 0.00000e + 00
\ Focal length 18.55 31.47 63.78
Variable interval \
D 3 2.99 15.69 30.86
D 9 20.72 11.28 2.61
D14 7.23 3.99 1.42
D19 0.49 8.88 24.55
Numerical example 4
f = 17.57 to 63.10 Fno = 3.47 to 5.85 2ω = 75.6 to 24.4
R 1 = 60.219 D 1 = 6.97 N 1 = 1.696797 ν 1 = 55.5
R 2 = -175.009 D 2 = 1.80 N 2 = 1.846660 ν 2 = 23.9
R 3 = 1970.686 D 3 = variable
R 4 = 85.053 D 4 = 1.40 N 3 = 1.804000 ν 3 = 46.6
R 5 = 11.644 D 5 = 6.16
R 6 = -56.088 D 6 = 1.10 N 4 = 1.772499 ν 4 = 49.6
R 7 = 24.731 D 7 = 0.12
R 8 = 19.514 D 8 = 3.50 N 5 = 1.805181 ν 5 = 25.4
R 9 = 2320.747 D 9 = variable
R10 = Aperture D10 = 0.80
R11 = 103.870 D11 = 1.74 N 6 = 1.487490 ν 6 = 70.2
R12 = -150.610 D12 = variable
R13 = 13.378 D13 = 5.26 N 7 = 1.487490 ν 7 = 70.2
R14 = -40.270 D14 = 1.00 N 8 = 1.846660 ν 8 = 23.9
R15 = 433.972 D15 = 5.94
R16 = 156.798 D16 = 1.70 N 9 = 1.491710 ν 9 = 57.4
* R17 = -111.139 D17 = Variable
R18 = ∞
Aspheric coefficient
17th: k = 0.00000e + 00 A = 0 B = 9.94868e-05 C = 1.49969e-07
D = 1.02746e-08 E = -3.81624e-11 F = 0.00000e + 00
\ Focal length 17.57 31.00 63.10
Variable interval \
D 3 2.55 15.08 26.60
D 9 18.37 11.28 5.28
D12 13.51 6.68 0.82
D17 0.47 9.72 28.38 Numerical example 5
f = 18.55 to 63.09 Fno = 3.53 to 5.85 2ω = 72.6 to 24.4
R 1 = 58.655 D 1 = 6.80 N 1 = 1.696797 ν 1 = 55.5
R 2 = -173.610 D 2 = 1.80 N 2 = 1.846660 ν 2 = 23.9
R 3 = 1129.100 D 3 = variable
R 4 = 91.613 D 4 = 1.40 N 3 = 1.670029 ν 3 = 47.2
R 5 = 11.308 D 5 = 6.38
R 6 = -67.146 D 6 = 1.10 N 4 = 1.772499 ν 4 = 49.6
R 7 = 23.445 D 7 = 0.12
R 8 = 18.790 D 8 = 3.60 N 5 = 1.846660 ν 5 = 23.9
R 9 = 108.872 D 9 = Variable
R10 = Aperture D10 = 2.73
R11 = 53.514 D11 = 2.00 N 6 = 1.487490 ν 6 = 70.2
R12 = 348.077 D12 = variable
R13 = 13.877 D13 = 5.67 N 7 = 1.487490 ν 7 = 70.2
R14 = -43.755 D14 = 1.00 N 8 = 1.846660 ν 8 = 23.9
R15 = 193.468 D15 = 5.37
R16 = 96.043 D16 = 1.90 N 9 = 1.491710 ν 9 = 57.4
* R17 = -72.083 D17 = variable
R18 = ∞
Aspheric coefficient
17th: k = 0.00000e + 00 A = 0 B = 8.58802e-05 C = 2.76497e-07
D = 2.61371e-09 E = 1.55605e-11 F = 0.00000e + 00
\ Focal length 18.55 28.22 63.09
Variable interval \
D 3 2.82 11.55 26.05
D 9 16.86 10.62 2.75
D12 10.86 6.60 1.03
D17 0.85 7.62 26.56
Numerical example 6
f = 20.00 to 78.02 Fno = 3.47 to 5.85 2ω = 68.5 to 19.8
R 1 = 58.092 D 1 = 6.50 N 1 = 1.712995 ν 1 = 53.9
R 2 = -195.337 D 2 = 1.80 N 2 = 1.846660 ν 2 = 23.9
R 3 = 613.798 D 3 = Variable
R 4 = 128.035 D 4 = 1.50 N 3 = 1.670029 ν 3 = 47.2
R 5 = 12.300 D 5 = 5.97
R 6 = -74.458 D 6 = 1.00 N 4 = 1.772499 ν 4 = 49.6
R 7 = 25.250 D 7 = 0.12 R 8 = 19.883 D 8 = 3.20 N 5 = 1.846660 ν 5 = 23.9
R 9 = 77.032 D 9 = Variable
R10 = Aperture D10 = 1.15
* R11 = 35.937 D11 = 2.20 N 6 = 1.491710 ν 6 = 57.4
R12 = 558.742 D12 = variable
R13 = 14.402 D13 = 5.28 N 7 = 1.487490 ν 7 = 70.2
R14 = -45.390 D14 = 1.00 N 8 = 1.846660 ν 8 = 23.9
R15 = 215.130 D15 = 6.01
R16 = 256.239 D16 = 2.30 N 9 = 1.524700 ν 9 = 56.2
* R17 = -78.926 D17 = Variable
R18 = ∞
Aspheric coefficient
11th: A = 0.00000e + 00 B = -2.19327e-06 C = 1.39344e-08
D = 0.00000e + 00 E = 0.00000e + 00 F = 0.00000e + 00
17th: k = 0.00000e + 00 A = 0 B = 7.69941e-05 C = 8.46426e-08
D = 7.32963e-09 E = -4.13547e-11 F = 0.00000e + 00
\ Focal length 20.00 31.30 78.02
Variable interval \
D 3 3.22 13.34 31.01
D 9 17.79 11.26 2.77
D12 12.63 7.68 1.16
D17 0.00 7.23 27.99

実施形態１のズームレンズの広角端のレンズ断面図Cross-sectional view of the zoom lens of Embodiment 1 at the wide-angle end 実施形態１のズームレンズの広角端、望遠端のズーム位置における収差図Aberration diagrams at the zoom positions of the wide-angle end and the telephoto end of the zoom lens according to Embodiment 1 実施形態１のズームレンズの広角端、望遠端のズーム位置における収差図Aberration diagrams at the zoom positions of the wide-angle end and the telephoto end of the zoom lens according to Embodiment 1 実施形態２のズームレンズの広角端のレンズ断面図Cross-sectional view of the zoom lens of Embodiment 2 at the wide-angle end 実施形態２のズームレンズの広角端、望遠端のズーム位置における収差図Aberration diagrams at the zoom positions of the wide-angle end and the telephoto end of the zoom lens according to the second embodiment. 実施形態２のズームレンズの広角端、望遠端のズーム位置における収差図Aberration diagrams at the zoom positions of the wide-angle end and the telephoto end of the zoom lens according to the second embodiment. 実施形態３のズームレンズの広角端のレンズ断面図Cross-sectional view of the zoom lens of Embodiment 3 at the wide-angle end 実施形態３のズームレンズの広角端、望遠端のズーム位置における収差図Aberration diagrams at the zoom positions of the wide-angle end and the telephoto end of the zoom lens according to Embodiment 3 実施形態３のズームレンズの広角端、望遠端のズーム位置における収差図Aberration diagrams at the zoom positions of the wide-angle end and the telephoto end of the zoom lens according to Embodiment 3 実施形態４のズームレンズの広角端のレンズ断面図Cross-sectional view of the zoom lens of Embodiment 4 at the wide-angle end 実施形態４のズームレンズの広角端、望遠端のズーム位置における収差図Aberration diagrams at the zoom positions of the wide-angle end and the telephoto end of the zoom lens according to Embodiment 4. 実施形態４のズームレンズの広角端、望遠端のズーム位置における収差図Aberration diagrams at the zoom positions of the wide-angle end and the telephoto end of the zoom lens according to Embodiment 4. 実施形態５のズームレンズの広角端のレンズ断面図Cross-sectional view of the zoom lens of Embodiment 5 at the wide-angle end 実施形態５のズームレンズの広角端、望遠端のズーム位置における収差図Aberration diagrams at the zoom positions of the wide-angle end and the telephoto end of the zoom lens according to Embodiment 5. 実施形態５のズームレンズの広角端、望遠端のズーム位置における収差図Aberration diagrams at the zoom positions of the wide-angle end and the telephoto end of the zoom lens according to Embodiment 5. 実施形態６のズームレンズの広角端のレンズ断面図Cross-sectional view of the zoom lens of Embodiment 6 at the wide-angle end 実施形態６のズームレンズの広角端、望遠端のズーム位置における収差図Aberration diagrams at the zoom positions of the wide-angle end and the telephoto end of the zoom lens according to the sixth embodiment. 実施形態６のズームレンズの広角端、望遠端のズーム位置における収差図Aberration diagrams at the zoom positions of the wide-angle end and the telephoto end of the zoom lens according to the sixth embodiment.

符号の説明Explanation of symbols

ΔＳサジタル
ΔＭメリジオナル
ＩＰ像面
ＳＰ絞り
ＦＳフレアーカット絞り
L1 第１群
L2 第２群
L3 第３群
L4 第４群 ΔS Sagittal ΔM Meridional IP Image plane SP Aperture FS Flare cut aperture
L1 first group
L2 2nd group
L3 3rd group
L4 4th group

Claims

物体側から順に、正の屈折力を有する第１群、負の屈折力を有する第２群、正の屈折力を有する第３群、正の屈折力を有する第４群より構成され、広角端から望遠端への変倍に際して、前記第１群と前記第２群の空気間隔が大きく、前記第２群と前記第３群の空気間隔が小さく、前記第３群と前記第４群の空気間隔が小さくなるように、前記第１群、前記第３群、前記第４群が物体側へ移動し、広角端におけるバックフォーカスをＳｋｗ、前記第３群の焦点距離をｆ３、前記第４群の焦点距離をｆ４、広角端における全系の焦点距離をｆｗとしたとき、
０．２＜ｆｗ／Ｓｋｗ＜０．６
０．０１＜ｆｗ／ｆ３＜０．４
１．３＜ｆ４／ｆｗ ≦ １．７８
なる条件を満足することを特徴とするズームレンズ。 In order from the object side, a first lens unit having a positive refractive power, a second lens unit having negative refractive power, a third group having a positive refractive power, is composed of a fourth group having a positive refractive power, the wide-angle end during zooming to the telephoto end from the first group and the second group of the air gap is large, the air gap of the third group and the second group is small, the air of the third group and the fourth group as distance decreases, the first group, the third group, the fourth group is moved toward the object side, SKW back focus at the wide-angle end, the focal length of the third group f3, the fourth group Is the focal length of f4, and the focal length of the entire system at the wide-angle end is fw.
0.2 <fw / Skw <0.6
0.01 <fw / f3 <0.4
1.3 <f4 / fw ≦ 1.78
A zoom lens characterized by satisfying the following conditions:

絞りからレンズ最終面までの広角端における距離をＤｐｗ、広角端におけるレンズ第１面からレンズ最終面までの距離をＴＤｗとしたとき、
０．５＜ｆｗ／Ｄｐｗ＜０．７
０．４＜Ｓｋｗ／ＴＤｗ＜０．８
なる条件を満足することを特徴とする請求項１に記載のズームレンズ。 Down Rikala lens distance at the wide-angle end to the final surface Dpw, when the distance from the first surface lens at the wide-angle end to the last lens surface and TDw,
0.5 <fw / Dpw <0.7
0.4 <Skw / TDw <0.8
The zoom lens according to claim 1, wherein the following condition is satisfied.

広角端から望遠端への変倍における前記第４群の移動量をｍ４としたとき、
−３．０＜ｍ４／ｆｗ＜ −０．４
なる条件を満足することを特徴とする請求項１または２に記載のズームレンズ。 When the wide-angle end to the movement amount of the fourth group in zooming to the telephoto end and m4,
−3.0 <m4 / fw <−0.4
The zoom lens according to claim 1 , wherein the following condition is satisfied.

前記第３群は１枚の正レンズから成ることを特徴とする請求項１乃至３のいずれか１項に記載のズームレンズ。 4. The zoom lens according to claim 1, wherein the third group includes one positive lens. 5.

前記第２群を光軸方向に移動させることにより無限遠から至近までのフォーカシングを行い、前記第２群の焦点距離をｆ２としたとき、
−１．０＜ｆ２／ｆｗ＜ −０．５
なる条件を満足することを特徴とする請求項１乃至４のいずれか１項に記載のズームレンズ。 When the second group is moved in the optical axis direction to perform focusing from infinity to the closest distance, and the focal length of the second group is f2 ,
−1.0 <f2 / fw <−0.5
The zoom lens according to claim 1 , wherein the following condition is satisfied.

前記第１群の焦点距離をｆ１としたとき、
０．１＜ｆｗ／ｆ１＜０．３
なる条件を満足することを特徴とする請求項１乃至５のいずれか１項に記載のズームレンズ。 When the focal length of the first group is f1 ,
0.1 <fw / f1 <0.3
The zoom lens according to claim 1 , wherein the following condition is satisfied.

前記第４群の最も像側にプラスチック非球面レンズを有し、該プラスチック非球面レンズの材質のアッベ数をＶｄとしたとき、
Ｖｄ＞５０
なる条件を満足することを特徴とする請求項１乃至６のいずれか１項に記載のズームレンズ。 When a plastic aspherical lens is provided on the most image side of the fourth group, and the Abbe number of the material of the plastic aspherical lens is Vd,
Vd> 50
The zoom lens according to claim 1 , wherein the following condition is satisfied.

前記第４群は、物体側から順に、正レンズ、負レンズ、プラスチックレンズを有することを特徴とする請求項１乃至７のいずれか１項に記載のズームレンズ。 The fourth group comprises, in order from the object side, a positive lens, a negative lens, a zoom lens according to any one of claims 1 to 7, characterized in that it has a plastic lens.

前記第１群は１枚の正レンズと１枚の負レンズから成ることを特徴とする請求項１乃至８のいずれか１項に記載のズームレンズ。 9. The zoom lens according to claim 1, wherein the first group includes one positive lens and one negative lens. 10.