JP2012208524A - Zoom lens and imaging apparatus having the same - Google Patents
Zoom lens and imaging apparatus having the same Download PDFInfo
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本発明はズームレンズに関し、例えば、デジタルスチルカメラやビデオカメラ等の撮像装置に好適なものである。 The present invention relates to a zoom lens, and is suitable for an imaging apparatus such as a digital still camera or a video camera.
最近、固体撮像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）には小型で高い光学性能を有するズームレンズが求められている。この種のカメラには、レンズ最後部と固体撮像素子との間に、ローパスフィルターや色補正フィルターなどの各種の光学部材が配置される。このため、これらのカメラに用いるズームレンズには、比較的バックフォーカスが長いことが要望されている。長いバックフォーカスを確保しやすい光学系として、負の屈折力のレンズ群が先行するネガティブリード型のズームレンズがある。 Recently, a zoom lens having a small size and high optical performance is required for an imaging apparatus (camera) such as a video camera or a digital still camera using a solid-state imaging device. In this type of camera, various optical members such as a low-pass filter and a color correction filter are disposed between the rearmost part of the lens and the solid-state imaging device. For this reason, zoom lenses used in these cameras are required to have a relatively long back focus. As an optical system that can ensure a long back focus, there is a negative lead type zoom lens preceded by a lens unit having a negative refractive power.
一方、カラー画像用の固体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、像側のテレセントリック特性の良いズームレンズであることが望まれている。従来、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、および正の屈折力の第３レンズ群より成り、小型で、しかも像側がテレセントリックである３群ズームレンズが知られている（特許文献１〜７）。 On the other hand, in the case of a color camera using a solid-state image sensor for color images, in order to avoid color shading, it is desired that the zoom lens has good telecentric characteristics on the image side. Conventionally, in order from the object side to the image side, a first lens unit having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power are small, and the image side is telecentric. 3 group zoom lenses are known (Patent Documents 1 to 7).
近年、ビデオカメラやデジタルカメラ等に用いるズームレンズには、広画角、高ズーム比で、しかも撮像素子の高性能化に伴い小型でかつ高い光学性能を有することが強く要望されている。前述した３群ズームレンズにおいて、全系の小型化を図りつつ、全ズーム範囲中で高い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ことが重要になってくる。 In recent years, zoom lenses for use in video cameras, digital cameras, and the like have been strongly demanded to have a wide angle of view and a high zoom ratio, as well as to have a small size and high optical performance as the performance of image pickup devices increases. In the above-described three-group zoom lens, in order to obtain high optical performance in the entire zoom range while reducing the size of the entire system, it is important to appropriately set the lens configuration of each lens group.
特に第１レンズ群を構成する各レンズのレンズ形状や各レンズの材料を適切に設定してズーミングに伴う諸収差の変動を小さくすることが重要になってくる。第１レンズ群のレンズ構成が不適切であると、全系の小型化を図りつつ、ズーミングに伴う諸収差の変動を少なくして全ズーム範囲にわたり高い光学性能を得るのが困難になってくる。 In particular, it is important to appropriately set the lens shape of each lens constituting the first lens group and the material of each lens to reduce fluctuations in various aberrations caused by zooming. If the lens configuration of the first lens group is inappropriate, it becomes difficult to obtain high optical performance over the entire zoom range by reducing the variation of various aberrations associated with zooming while reducing the size of the entire system. .
本発明は、レンズ系全体がコンパクトで、全ズーム範囲中で高い光学性能が得られるズームレンズ及びそれを有する撮像装置の提供を目的とする。 An object of the present invention is to provide a zoom lens in which the entire lens system is compact and high optical performance can be obtained in the entire zoom range, and an image pickup apparatus having the zoom lens.
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レンズ群より構成され、各レンズ群を移動させてズーミングを行うズームレンズにおいて、第１レンズ群は、物体側より像側へ順に、負の屈折力の第１１レンズと正の屈折力の第１２レンズより構成され、前記第１１レンズの材料の屈折率をＮ１１、前記第１２レンズの材料のアッベ数をν１２、前記第１１レンズの物体側および像側のレンズ面の曲率半径を各々Ｒ１１ａ、Ｒ１１ｂ、前記第１２レンズの物体側のレンズ面の曲率半径をＲ１２ａ、前記第１レンズ群の焦点距離をｆ１、望遠端における全系の焦点距離をｆｔとするとき
１．８１＜Ｎ１１
ν１２＜１９
０＜（Ｒ１１ａ＋Ｒ１１ｂ）／（Ｒ１１ａ−Ｒ１１ｂ）≦１．０
−７．０＜（Ｒ１１ｂ＋Ｒ１２ａ）／（Ｒ１１ｂ−Ｒ１２ａ）＜−３．０
０．３＜｜ｆ１｜／ｆｔ＜０．６
なる条件を満足することを特徴としている。
The zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. In the zoom lens that performs zooming by moving the group, the first lens group includes, in order from the object side to the image side, an eleventh lens having a negative refractive power and a twelfth lens having a positive refractive power. The refractive index of the lens material is N11, the Abbe number of the twelfth lens material is ν12, the radius of curvature of the object-side and image-side lens surfaces of the eleventh lens is R11a and R11b, and the object side of the twelfth lens When the radius of curvature of the lens surface is R12a, the focal length of the first lens unit is f1, and the focal length of the entire system at the telephoto end is ft, 1.81 <N11
ν12 <19
0 <(R11a + R11b) / (R11a−R11b) ≦ 1.0
−7.0 <(R11b + R12a) / (R11b−R12a) <− 3.0
0.3 <| f1 | / ft <0.6
It is characterized by satisfying the following conditions.
この他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レンズ群より構成され、各レンズ群を移動させてズーミングを行うズームレンズにおいて、第１レンズ群は、物体側より像側へ順に、負の屈折力の第１１レンズと正の屈折力の第１２レンズより構成され、前記第１１レンズの材料の屈折率をＮ１１、前記第１２レンズの材料のアッベ数をν１２、前記第１１レンズの物体側および像側のレンズ面の曲率半径を各々Ｒ１１ａ、Ｒ１１ｂ、広角端から望遠端へのズーミングにおける前記第２レンズ群の光軸方向の移動距離をＭ２、広角端における全系の焦点距離をｆｗとするとき
１．８１＜Ｎ１１
ν１２＜１９
０＜（Ｒ１１ａ＋Ｒ１１ｂ）／（Ｒ１１ａ−Ｒ１１ｂ）≦１．０
３．５＜Ｍ２／ｆｗ＜５．０
なる条件を満足することを特徴としている。
In addition, the zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. In the zoom lens that performs zooming by moving each lens group, the first lens group is composed of an eleventh lens having a negative refractive power and a twelfth lens having a positive refractive power in order from the object side to the image side. The refractive index of the eleventh lens material is N11, the Abbe number of the twelfth lens material is ν12, the radius of curvature of the object-side and image-side lens surfaces of the eleventh lens is R11a, R11b, and the wide-angle end to the telephoto end, respectively. When the moving distance in the optical axis direction of the second lens unit during zooming is M2, and the focal length of the entire system at the wide angle end is fw, 1.81 <N11
ν12 <19
0 <(R11a + R11b) / (R11a−R11b) ≦ 1.0
3.5 <M2 / fw <5.0
It is characterized by satisfying the following conditions.
この他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レンズ群より構成され、各レンズ群を移動させてズーミングを行うズームレンズにおいて、第１レンズ群は、物体側より像側へ順に、負の屈折力の第１１レンズと正の屈折力の第１２レンズより構成され、前記第１１レンズの材料の屈折率をＮ１１、前記第１２レンズの材料のアッベ数をν１２、前記第１１レンズの物体側および像側のレンズ面の曲率半径を各々Ｒ１１ａ、Ｒ１１ｂ、前記第１２レンズの物体側のレンズ面の曲率半径をＲ１２ａとするとき
１．８１＜Ｎ１１
ν１２＜１９
０＜（Ｒ１１ａ＋Ｒ１１ｂ）／（Ｒ１１ａ−Ｒ１１ｂ）≦１．０
−６．０＜（Ｒ１１ｂ＋Ｒ１２ａ）／（Ｒ１１ｂ−Ｒ１２ａ）＜−３．５
なる条件を満足することを特徴としている。
In addition, the zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. In the zoom lens that performs zooming by moving each lens group, the first lens group is composed of an eleventh lens having a negative refractive power and a twelfth lens having a positive refractive power in order from the object side to the image side. The refractive index of the eleventh lens material is N11, the Abbe number of the twelfth lens material is ν12, the radiuses of curvature of the object-side and image-side lens surfaces of the eleventh lens are R11a, R11b, and the twelfth lens, respectively. When the radius of curvature of the lens surface on the object side is R12a, 1.81 <N11
ν12 <19
0 <(R11a + R11b) / (R11a−R11b) ≦ 1.0
−6.0 <(R11b + R12a) / (R11b−R12a) <− 3.5
It is characterized by satisfying the following conditions.
この他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レンズ群より構成され、各レンズ群を移動させてズーミングを行うズームレンズにおいて、第１レンズ群は、物体側より像側へ順に、負の屈折力の第１１レンズと正の屈折力の第１２レンズより構成され、前記第２レンズ群は、最も物体側に、物体側の面が凸形状の正の屈折力の第２１レンズを有し、前記第１１レンズの材料の屈折率をＮ１１、前記第１２レンズの材料のアッベ数をν１２、前記第１１レンズの物体側および像側のレンズ面の曲率半径を各々Ｒ１１ａ、Ｒ１１ｂ、前記第２１レンズの材料の屈折率をＮ２１とするとき
１．８１＜Ｎ１１
ν１２＜１９
０＜（Ｒ１１ａ＋Ｒ１１ｂ）／（Ｒ１１ａ−Ｒ１１ｂ）≦１．０
１．８２＜Ｎ２１
なる条件を満足することを特徴としている。
In addition, the zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. In the zoom lens that performs zooming by moving each lens group, the first lens group is composed of an eleventh lens having a negative refractive power and a twelfth lens having a positive refractive power in order from the object side to the image side. The second lens group has a 21st lens having a positive refractive power and a convex surface on the object side closest to the object side. The refractive index of the material of the 11th lens is N11, and the material of the 12th lens is When Abbe number is ν12, the radius of curvature of the object-side and image-side lens surfaces of the eleventh lens is R11a and R11b, and the refractive index of the material of the twenty-first lens is N21, 1.81 <N11
ν12 <19
0 <(R11a + R11b) / (R11a−R11b) ≦ 1.0
1.82 <N21
It is characterized by satisfying the following conditions.
本発明によれば、レンズ系全体がコンパクトで、全ズーム範囲中で高い光学性能が得られるズームレンズ及びそれを有する撮像装置が得られる。 According to the present invention, it is possible to obtain a zoom lens having a compact lens system and high optical performance in the entire zoom range, and an imaging apparatus having the same.
以下に本発明の好ましい実施の形態を添付の図面に基づいて詳細に説明する。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レンズ群より構成され、各レンズ群を移動させてズーミングを行うズームレンズである。 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. This is a zoom lens that moves a group to perform zooming.
図１は本発明の実施例１のズームレンズの広角端（短焦点距離端）におけるレンズ断面図である。図２（Ａ）、（Ｂ）、（Ｃ）はそれぞれ実施例１のズームレンズの広角端、中間のズーム位置、望遠端（長焦点距離端）における収差図である。実施例１はズーム比４．７１、開口比２．９４〜６．００程度のズームレンズである。 FIG. 1 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to Embodiment 1 of the present invention. FIGS. 2A, 2B, and 2C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end (long focal length end), respectively, of the zoom lens according to the first exemplary embodiment. Example 1 is a zoom lens having a zoom ratio of 4.71 and an aperture ratio of about 2.94 to 6.00.
図３は本発明の実施例２のズームレンズの広角端におけるレンズ断面図である。図４（Ａ）、（Ｂ）、（Ｃ）はそれぞれ実施例２のズームレンズの広角端、中間のズーム位置、望遠端における収差図である。実施例２はズーム比４．７２、開口比２．８８〜６．０５程度のズームレンズである。 FIG. 3 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 2 of the present invention. 4A, 4B, and 4C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the second embodiment. The second embodiment is a zoom lens having a zoom ratio of 4.72 and an aperture ratio of about 2.88 to 6.05.
図５は本発明の実施例３のズームレンズの広角端におけるレンズ断面図である。図６（Ａ）、（Ｂ）、（Ｃ）はそれぞれ実施例３のズームレンズの広角端、中間のズーム位置、望遠端における収差図である。実施例３はズーム比４．７５、開口比２．７３〜６．０６程度のズームレンズである。図７は本発明の実施例４のズームレンズの広角端におけるレンズ断面図である。図８（Ａ）、（Ｂ）、（Ｃ）はそれぞれ実施例４のズームレンズの広角端、中間のズーム位置、望遠端における収差図である。実施例６はズーム比４．４７、開口比２．８３〜６．１０程度のズームレンズである。 FIG. 5 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 3 of the present invention. FIGS. 6A, 6B, and 6C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the third exemplary embodiment. Embodiment 3 is a zoom lens having a zoom ratio of 4.75 and an aperture ratio of about 2.73 to 6.06. FIG. 7 is a lens cross-sectional view at the wide-angle end of the zoom lens according to a fourth exemplary embodiment of the present invention. 8A, 8B, and 8C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the fourth exemplary embodiment. The sixth exemplary embodiment is a zoom lens having a zoom ratio of 4.47 and an aperture ratio of about 2.83 to 6.10.
図９は本発明の実施例５のズームレンズの広角端におけるレンズ断面図である。図１０（Ａ）、（Ｂ）、（Ｃ）はそれぞれ実施例５のズームレンズの広角端、中間のズーム位置、望遠端における収差図である。実施例６はズーム比４．６３、開口比２．８８〜７．７８程度のズームレンズである。図１１は本発明のズームレンズを備えるデジタルスチルカメラの要部概略図である。 FIG. 9 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 5 of the present invention. FIGS. 10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 5 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively. Example 6 is a zoom lens having a zoom ratio of 4.63 and an aperture ratio of about 2.88 to 7.78. FIG. 11 is a schematic view of a main part of a digital still camera provided with the zoom lens of the present invention.
各実施例のズームレンズは撮像装置に用いられる撮影レンズ系であり、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。レンズ断面図において、ｉは物体側から像側への各レンズ群の順序を示し、Ｌｉは第ｉレンズ群である。実施例１〜５のズームレンズの特徴について説明する。図１、図３、図５、図７、図９のレンズ断面図において、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。 The zoom lens of each embodiment is a photographing lens system used in an imaging apparatus. In the lens cross-sectional view, the left side is the subject side (front) and the right side is the image side (rear). In the lens cross-sectional view, i indicates the order of the lens groups from the object side to the image side, and Li is the i-th lens group. The features of the zoom lenses of Examples 1 to 5 will be described. In the lens cross-sectional views of FIGS. 1, 3, 5, 7, and 9, L1 is a first lens unit having a negative refractive power (optical power = reciprocal of focal length), and L2 is a first lens unit having a positive refractive power. The second lens group, L3, is a third lens group having a positive refractive power.
ＳＰは開放Ｆナンバー（Ｆｎｏ）光束を決定（制限）する開口絞りの作用をするＦナンバー決定部材（以下「開口絞り」ともいう。）であり、第２レンズ群Ｌ２の像側に配置されている。Ｇは光学フィルター、フェースプレート、水晶ローパスフィルター、赤外カットフィルター等に相当する光学ブロックである。ＩＰは像面であり、ビデオカメラやデジタルスチルカメラの撮影光学系として使用する際にはＣＣＤセンサやＣＭＯＳセンサ等の固体撮像素子（光電変換素子）の撮像面が置かれる。 SP is an F-number determining member (hereinafter also referred to as “aperture stop”) that functions as an aperture stop that determines (limits) an open F-number (Fno) light beam, and is disposed on the image side of the second lens unit L2. Yes. G is an optical block corresponding to an optical filter, a face plate, a quartz low-pass filter, an infrared cut filter, or the like. IP is an image plane, and when used as a photographing optical system of a video camera or a digital still camera, an imaging plane of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is placed.
又、銀塩フィルム用カメラの撮影光学系として使用する際にはフィルム面に相当する感光面が置かれている。収差図において、ＦｎｏはＦナンバー、ｄ、ｇは各々ｄ線及びｇ線、ΔＭ、ΔＳはメリディオナル像面、サジタル像面、倍率色収差はｇ線によって表している。ωは半画角である。尚、以下の各実施例において広角端と望遠端は変倍用レンズ群（第２レンズ群Ｌ２）が機構上、光軸上移動可能な範囲の両端に位置したときのズーム位置をいう。 Further, when used as a photographing optical system for a silver salt film camera, a photosensitive surface corresponding to the film surface is provided. In the aberration diagrams, Fno is an F number, d and g are d and g lines, respectively, ΔM and ΔS are meridional image surfaces, sagittal image surfaces, and lateral chromatic aberration are expressed by g lines. ω is a half angle of view. In each of the following embodiments, the wide-angle end and the telephoto end refer to zoom positions when the zoom lens unit (second lens unit L2) is positioned at both ends of the range in which it can move on the optical axis due to the mechanism.
各実施例のズームレンズでは、広角端から望遠端のズーム位置へのズーミングに際して、第１レンズ群Ｌ１が像側に凸状の軌跡で略往復移動する。又、第２レンズ群Ｌ２が物体側に移動し、第３レンズ群Ｌ３が像側に移動している。このとき広角端に比べ望遠端での第１レンズ群Ｌ１と第２レンズ群Ｌ２との間隔が小さく、第２レンズ群Ｌ２と第３レンズ群Ｌ３との間隔が大きくなるように各レンズ群が移動してズーミングを行っている。各実施例のズームレンズは、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の往復移動によって変倍に伴う像点の移動を補正している。 In the zoom lens of each embodiment, during zooming from the wide-angle end to the telephoto end zoom position, the first lens unit L1 substantially reciprocates along a locus convex toward the image side. Further, the second lens unit L2 has moved to the object side, and the third lens unit L3 has moved to the image side. At this time, each lens unit is arranged such that the distance between the first lens unit L1 and the second lens unit L2 at the telephoto end is smaller than that at the wide-angle end, and the interval between the second lens unit L2 and the third lens unit L3 is increased. Move and zoom. The zoom lens of each embodiment performs main zooming by moving the second lens unit L2, and corrects the movement of the image point accompanying zooming by the reciprocating movement of the first lens unit L1.
第３レンズ群Ｌ３の移動により副変倍を行い、１つのレンズ群で変倍を行う場合に対し、各レンズ群の屈折力の増大を防いでいる。無限遠物体から近距離物体へのフォーカシングは第３レンズ群Ｌ３を物体側へ移動させて行っている。Ｆナンバー決定部材ＳＰは、光軸方向に関して、第２レンズ群Ｌ２の像側に配置している。開口絞りＳＰをこのような位置に配置することにより望遠端における第１レンズ群Ｌ１と第２レンズ群Ｌ２の間隔が詰められる。 Sub-magnification is performed by moving the third lens unit L3, and increase in refractive power of each lens unit is prevented as compared with the case where magnification is performed by one lens unit. Focusing from an infinitely distant object to a close object is performed by moving the third lens unit L3 to the object side. The F-number determining member SP is disposed on the image side of the second lens unit L2 with respect to the optical axis direction. By disposing the aperture stop SP at such a position, the distance between the first lens unit L1 and the second lens unit L2 at the telephoto end is reduced.
このため、ズーミングのための第２レンズ群Ｌ２の物体側への移動量を十分確保することができる。これにより高ズーム化としながら望遠端におけるレンズ全長の増大を防いでいる。なお各実施例では各ズーム位置においてＦナンバー決定部材ＳＰの開口寸法を変えて各ズーム位置の最小Ｆｎｏ（Ｆナンバー）を決定している。このようにすることで広角端と望遠端においてＦナンバーを個別に設定できるため広角端と望遠端のFナンバーの変化を低減するとともに第２レンズ群Ｌ２の有効径の増大を防いでいる。 For this reason, a sufficient amount of movement of the second lens unit L2 to the object side for zooming can be ensured. This prevents an increase in the total lens length at the telephoto end while achieving a high zoom. In each embodiment, the minimum Fno (F number) of each zoom position is determined by changing the opening size of the F number determination member SP at each zoom position. In this way, since the F number can be set individually at the wide angle end and the telephoto end, the change in the F number at the wide angle end and the telephoto end is reduced and the effective diameter of the second lens unit L2 is prevented from increasing.
各実施例において、第１レンズ群Ｌ１は物体側より順に負の第１１レンズＧ１１、正の第１２レンズＧ１２より構成している。これにより色収差を良好に補正しながら必要最低限のレンズ枚数として第１レンズ群Ｌ１の小型化を図っている。 In each embodiment, the first lens unit L1 includes a negative eleventh lens G11 and a positive twelfth lens G12 in order from the object side. As a result, the first lens unit L1 is reduced in size as a minimum number of lenses while correcting chromatic aberration well.
更に第１レンズ群Ｌ１の負の第１１レンズＧ１１は低分散材料、正の第１２レンズＧ１２は高分散材料を用いることにより色収差の補正のために必要な負の第１１レンズＧ１１、正の第１２レンズＧ１２の屈折力を極力緩めて各レンズの厚みを薄型化している。更に負の第１１レンズＧ１１、正の第１２レンズＧ１２ともに高屈折率材料を用いて第１レンズ群Ｌ１の、より一層の薄型化を図っている。 Further, the negative eleventh lens G11 of the first lens unit L1 is made of a low dispersion material, and the positive twelfth lens G12 is made of a high dispersion material. The refractive power of the 12 lens G12 is relaxed as much as possible to reduce the thickness of each lens. Further, both the negative eleventh lens G11 and the positive twelfth lens G12 use a high refractive index material to further reduce the thickness of the first lens unit L1.
各実施例において、負の第１１レンズＧ１１の材料の屈折率をＮ１１、正の第１２レンズＧ１２の材料のアッベ数をν１２、負の第１１レンズの物体側および像側のレンズ面の曲率半径を各々Ｒ１１ａ、Ｒ１１ｂとする。このとき
１．８１＜Ｎ１１ ‥‥（１）
ν１２＜１９ ‥‥（２）
０＜（Ｒ１１ａ＋Ｒ１１ｂ）／（Ｒ１１ａ−Ｒ１１ｂ）≦１．０ ‥‥（３）
なる条件を満足している。
In each embodiment, the refractive index of the material of the negative eleventh lens G11 is N11, the Abbe number of the material of the positive twelfth lens G12 is ν12, and the radius of curvature of the object-side and image-side lens surfaces of the negative eleventh lens is Are R11a and R11b, respectively. At this time 1.81 <N11 (1)
ν12 <19 (2)
0 <(R11a + R11b) / (R11a-R11b) ≦ 1.0 (3)
Is satisfied.
条件式（１）は第１レンズ群Ｌ１を構成する負の第１１レンズＧ１１の材料の屈折率を規定する式である。条件式（１）の下限を超えて屈折率が小さいと所望の屈折力とするためにはレンズ外周部が厚くなり第１レンズ群Ｌ１の薄型化が困難になる。また広角側において、像面湾曲が多く発生するので良くない。 Conditional expression (1) defines the refractive index of the material of the negative eleventh lens G11 constituting the first lens unit L1. If the refractive index is small beyond the lower limit of conditional expression (1), the lens outer peripheral portion becomes thick in order to obtain a desired refractive power, and it is difficult to reduce the thickness of the first lens unit L1. In addition, on the wide angle side, a lot of field curvature occurs, which is not good.
条件式（２）は第１レンズ群Ｌ１を構成する正の第１２レンズＧ１２の材料のアッベ数を規定する式である。条件式（２）の上限を超えてアッベ数が大きいと色収差補正のために必要となる正の第１２レンズＧ１２の屈折力が強まり正の第１２レンズＧ１２が厚くなるため第１レンズ群Ｌ１の薄型化が困難になる。 Conditional expression (2) defines the Abbe number of the material of the positive twelfth lens G12 constituting the first lens unit L1. If the Abbe number is larger than the upper limit of conditional expression (2), the refractive power of the positive twelfth lens G12 required for chromatic aberration correction increases and the positive twelfth lens G12 becomes thicker. Thinning becomes difficult.
条件式（３）は第１レンズ群Ｌ１を構成する負の第１１レンズＧ１１のシェープファクター（レンズ形状）を規定する式である。前玉径を小型化するためには入射瞳位置を極力、物体側に位置するようにするのがよい。このためには負の第１１レンズＧ１１は物体側のレンズ面が物体側に凸形状とするよりも凹形状とする方がよい。条件式（３）の上限を超えて物体側に凸面を向けたメニスカス形状となりすぎると入射瞳位置が像側に大きく位置するようになり、前玉径が増大してくる。 Conditional expression (3) defines the shape factor (lens shape) of the negative eleventh lens G11 constituting the first lens unit L1. In order to reduce the diameter of the front lens, it is preferable that the entrance pupil position be located on the object side as much as possible. For this purpose, the negative eleventh lens G11 should have a concave shape rather than a convex lens surface on the object side. If the upper limit of the conditional expression (3) is exceeded and the meniscus shape is convex toward the object side, the entrance pupil position becomes larger on the image side and the front lens diameter increases.
又、下限を超えて物体側のレンズ面が物体側に凹面を向けた形状となり、その曲率が大きくなると、広角側において像面湾曲および望遠側において球面収差の発生が多くなってくるので良くない。更に好ましくは条件式（１），（３）の数値範囲を次の如く設定することが好ましい。 Also, if the lens surface on the object side exceeds the lower limit and the concave surface is directed to the object side and the curvature increases, the curvature of field on the wide-angle side and spherical aberration on the telephoto side increase, which is not good. . More preferably, the numerical ranges of conditional expressions (1) and (3) are set as follows.
１．８２５＜Ｎ１１ ‥‥（１ａ）
０．３＜（Ｒ１１ａ＋Ｒ１１ｂ）／（Ｒ１１ａ−Ｒ１１ｂ）≦１．０ ‥‥（３ａ）
以上のように各実施例によればズーム比４倍以上の高ズーム比でかつ広角端の半画角が３７°以上の広画角でありながら前玉径の小型化を図ったコンパクトなズームレンズが得られる。各実施例において、更に好ましくは次の諸条件のうち１以上を満足するのが良い。
1.825 <N11 (1a)
0.3 <(R11a + R11b) / (R11a-R11b) ≦ 1.0 (3a)
As described above, according to each embodiment, a compact zoom in which the front lens diameter is reduced while having a high zoom ratio of 4 times or more and a wide angle of view with a half angle of view of 37 ° or more at the wide angle end. A lens is obtained. In each embodiment, it is more preferable to satisfy one or more of the following conditions.
第１レンズ群Ｌ１の正の第１２レンズＧ１２の像側のレンズ面の曲率半径をＲ１２ｂとする。第１レンズ群Ｌ１の正の第１２レンズＧ１２の物体側のレンズ面の曲率半径をＲ１２ａとする。第１レンズ群Ｌ１の負の第１１レンズＧ１１の材料のアッベ数をν１１、正の第１２レンズＧ１２の材料の屈折率をＮ１２とする。第１レンズ群Ｌ１、第２レンズ群Ｌ２、第３レンズ群Ｌ３の焦点距離を順にｆ１、ｆ２、ｆ３とする。広角端と望遠端における全系の焦点距離を各々ｆｗ、ｆｔとする。 The radius of curvature of the image-side lens surface of the positive twelfth lens G12 of the first lens unit L1 is R12b. Let R12a be the radius of curvature of the object-side lens surface of the positive twelfth lens G12 of the first lens unit L1. The Abbe number of the material of the negative eleventh lens G11 of the first lens unit L1 is ν11, and the refractive index of the material of the positive twelfth lens G12 is N12. The focal lengths of the first lens unit L1, the second lens unit L2, and the third lens unit L3 are sequentially set as f1, f2, and f3. The focal lengths of the entire system at the wide-angle end and the telephoto end are fw and ft, respectively.
第２レンズ群Ｌ２の広角端から望遠端に至る光軸方向の移動距離（移動量）をＭ２とする。第１レンズ群Ｌ１の正の第１２レンズＧ１２の焦点距離をｆ１２とする。第２レンズ群Ｌ２は最も物体側に、物体側の面が凸形状の正の第２１レンズＧ２１を有し、正の第２１レンズＧ２１の材料の屈折率をＮ２１とする。このとき、次の条件式のうち１以上を満足するのが良い。 The moving distance (moving amount) in the optical axis direction from the wide-angle end to the telephoto end of the second lens unit L2 is M2. The focal length of the positive twelfth lens G12 of the first lens unit L1 is defined as f12. The second lens unit L2 has a positive 21st lens G21 whose surface on the object side is convex on the most object side, and the refractive index of the material of the positive 21st lens G21 is N21. At this time, it is preferable to satisfy one or more of the following conditional expressions.
−０．５＜（Ｒ１１ａ＋Ｒ１２ｂ）／（Ｒ１１ａ−Ｒ１２ｂ）≦１．０ ‥‥（４）
−７．０＜（Ｒ１１ｂ＋Ｒ１２ａ）／（Ｒ１１ｂ−Ｒ１２ａ）＜−３．０ ‥‥（５）
３０＜ν１１＜５０ ‥‥（６）
１．９０＜Ｎ１２ ‥‥（７）
０．３＜｜ｆ１｜／ｆｔ＜０．６ ‥‥（８）
０．３＜ｆ２／ｆｔ＜０．６ ‥‥（９）
０．６＜ｆ３／ｆｔ＜１．２ ‥‥（１０）
３．５＜Ｍ２／ｆｗ＜５．０ ‥‥（１１）
１．４＜ｆ１２／｜ｆ１｜＜２．５ ‥‥（１２）
１．８＜Ｎ２１ ‥‥（１３）
条件式（４）は第１レンズ群Ｌ１を構成する最も物体側である負の第１１レンズＧ１１の物体側のレンズ面と第１レンズ群Ｌ１の最も像側である正の第１２レンズＧ１２の像側のレンズ面を規定する式である。
−0.5 <(R11a + R12b) / (R11a−R12b) ≦ 1.0 (4)
−7.0 <(R11b + R12a) / (R11b−R12a) <− 3.0 (5)
30 <ν11 <50 (6)
1.90 <N12 (7)
0.3 <| f1 | / ft <0.6 (8)
0.3 <f2 / ft <0.6 (9)
0.6 <f3 / ft <1.2 (10)
3.5 <M2 / fw <5.0 (11)
1.4 <f12 / | f1 | <2.5 (12)
1.8 <N21 (13)
Conditional expression (4) indicates that the object-side lens surface of the negative eleventh lens G11 that is the most object side and the positive twelfth lens G12 that is the most image side of the first lens group L1. It is a formula that defines the lens surface on the image side.
すなわち第１レンズ群Ｌ１の入射面と射出面の形状を規定する式である。条件式（４）の上限を超えて負の第１１レンズＧ１１の物体側のレンズ面と正の第１２レンズＧ１２の像側のレンズ面がともに物体側に凸形状となると望遠側において球面収差の高次成分が多く発生してくる。又、下限を超えて正の第１２レンズＧ１２の像側のレンズ面よりも負の第１１レンズＧ１１の物体側のレンズ面の曲率が大きくなりすぎると第１レンズ群Ｌ１の主点位置が物体側に偏りすぎる。これにより望遠端において第１レンズ群Ｌ１と第２レンズ群Ｌ２の間隔を十分取ることが難しくなり高ズーム比化（高変倍化）が困難になる。 That is, this is an expression that defines the shape of the entrance surface and exit surface of the first lens unit L1. If both the object-side lens surface of the negative eleventh lens G11 and the image-side lens surface of the positive twelfth lens G12 are convex on the object side beyond the upper limit of conditional expression (4), spherical aberration will occur on the telephoto side. Many higher-order components are generated. If the curvature of the object-side lens surface of the negative eleventh lens G11 exceeds the lower limit beyond the image-side lens surface of the positive twelfth lens G12, the principal point position of the first lens unit L1 becomes an object. Too biased to the side. As a result, it is difficult to provide a sufficient distance between the first lens unit L1 and the second lens unit L2 at the telephoto end, and it becomes difficult to achieve a high zoom ratio (high zoom ratio).
条件式（５）は負の第１１レンズＧ１１と正の第１２レンズＧ１２で構成される空気レンズのシェープファクターを規定する式である。条件式（５）を満たす空気レンズの形状は物体側に凸面を向けたメニスカス形状である。上限を超えてメニスカスの度合いが弱まりすぎると広角側において像面湾曲、非点収差等の発生が多くなる。又下限を超えてメニスカスの度合いが強まりすぎると望遠側において球面収差、軸上色収差の発生が多くなってくる。 Conditional expression (5) is an expression that defines the shape factor of the air lens composed of the negative eleventh lens G11 and the positive twelfth lens G12. The shape of the air lens that satisfies the conditional expression (5) is a meniscus shape having a convex surface facing the object side. If the upper limit is exceeded and the degree of meniscus becomes too weak, the occurrence of field curvature, astigmatism, etc. increases on the wide angle side. If the lower limit is exceeded and the meniscus is too strong, spherical aberration and longitudinal chromatic aberration will increase on the telephoto side.
条件式（６）は第１レンズ群Ｌ１の負の第１１レンズＧ１１の材料のアッベ数を規定する式である。条件式（６）の上限を超えてアッベ数が大きすぎると、すなわち低分散すぎると一般的な光学ガラスでは屈折率が低くなるため負の第１１レンズＧ１１の薄型化が困難になる。又、下限を超えてアッベ数が小さすぎるとすなわち高分散すぎると広角端において倍率色収差、望遠端において軸上色収差の発生が多くなってくる。 Conditional expression (6) defines the Abbe number of the material of the negative eleventh lens G11 of the first lens unit L1. When the upper limit of conditional expression (6) is exceeded and the Abbe number is too large, that is, when the dispersion is too low, the refractive index of a general optical glass is low, so that it is difficult to reduce the thickness of the negative eleventh lens G11. On the other hand, if the Abbe number is too small beyond the lower limit, that is, if the dispersion is too high, lateral chromatic aberration occurs at the wide-angle end and axial chromatic aberration increases at the telephoto end.
条件式（７）は第１レンズ群Ｌ１の正の第１２レンズＧ１２の材料の屈折率を規定する式である。条件式（７）の下限を超えて屈折率が小さすぎると正の第１２レンズＧ１２の薄型化が困難になる。また正の第１２レンズＧ１２が厚いと望遠端において第１レンズ群Ｌ１と第２レンズ群Ｌ２の間隔をとることが難しくなり高ズーム比化が困難になる。 Conditional expression (7) defines the refractive index of the material of the positive twelfth lens G12 of the first lens unit L1. If the lower limit of conditional expression (7) is exceeded and the refractive index is too small, it is difficult to reduce the thickness of the positive twelfth lens G12. On the other hand, if the positive twelfth lens G12 is thick, it is difficult to keep the distance between the first lens unit L1 and the second lens unit L2 at the telephoto end, and it becomes difficult to achieve a high zoom ratio.
条件式（８）は第１レンズ群Ｌ１の焦点距離を規定する式である。条件式（８）の上限を超えて第１レンズ群Ｌ１の焦点距離が長くなりすぎると広角端においてレンズ全長（第１レンズ面から像面までの距離）が増大してくる。又、下限を超えて第１レンズ群Ｌ１の焦点距離が短くなりすぎると第１レンズ群Ｌ１で諸収差が多く発生してくる。特に広角側において像面湾曲、倍率色収差、望遠側において球面収差、コマ収差の発生が多くなってくる。 Conditional expression (8) defines the focal length of the first lens unit L1. If the upper limit of conditional expression (8) is exceeded and the focal length of the first lens unit L1 becomes too long, the total lens length (distance from the first lens surface to the image plane) increases at the wide angle end. If the focal length of the first lens unit L1 becomes too short beyond the lower limit, many aberrations occur in the first lens unit L1. In particular, field curvature and lateral chromatic aberration occur on the wide angle side, and spherical aberration and coma aberration increase on the telephoto side.
条件式（９）は第２レンズ群Ｌ２の焦点距離を規定する式である。条件式（９）の上限を超えて第２レンズ群Ｌ２の焦点距離が長くなりすぎると所望のズーム比を得るために必要な第２レンズ群Ｌ２の移動量が長くなりすぎ、望遠端においてレンズ全長が増大してくる。 Conditional expression (9) defines the focal length of the second lens unit L2. If the upper limit of conditional expression (9) is exceeded and the focal length of the second lens unit L2 becomes too long, the amount of movement of the second lens unit L2 necessary to obtain a desired zoom ratio becomes too long, and the lens at the telephoto end The total length increases.
特にレンズを保持するレンズ鏡筒が沈胴する構成の場合には沈胴長を短縮しようとすると鏡筒構造が複雑になりユニットが大型化し、複雑化してくるので良くない。下限を超えて第２レンズ群Ｌ２の焦点距離が短くなりすぎると第２レンズ群Ｌ２より諸収差の発生が多くなってくる。特にズーム範囲全般（変倍全域）に渡って球面収差、コマ収差、軸上色収差が多く発生してくる。 In particular, in the case where the lens barrel holding the lens is retracted, it is not good because if the retractable length is shortened, the structure of the lens barrel becomes complicated and the unit becomes large and complicated. When the focal length of the second lens unit L2 becomes too short beyond the lower limit, various aberrations are generated more than the second lens unit L2. In particular, a large amount of spherical aberration, coma, and axial chromatic aberration occurs over the entire zoom range (entire zoom range).
条件式（１０）は第３レンズ群Ｌ３の焦点距離を規定する式である。条件式（１０）の上限を超えて第３レンズ群Ｌ３の焦点距離が長くなりすぎると軸外光束を屈曲させる作用が弱まるため像面への入射角度が大きくなりすぎる。そうすると固体撮像素子へ光の取り込み効率が悪化しシェーディングの発生が多くなってくる。下限を超えて第３レンズ群Ｌ３の焦点距離が短くなりすぎると第３レンズ群Ｌ３で発生する諸収差が多くなってくる。 Conditional expression (10) defines the focal length of the third lens unit L3. If the upper limit of conditional expression (10) is exceeded and the focal length of the third lens unit L3 becomes too long, the action of bending the off-axis light beam will weaken, and the incident angle on the image plane will become too large. As a result, the efficiency of capturing light into the solid-state image sensor deteriorates, and shading increases. When the lower limit is exceeded and the focal length of the third lens unit L3 becomes too short, various aberrations generated in the third lens unit L3 increase.
特にズーム範囲全般（変倍全域）に渡り倍率色収差、像面湾曲が多く発生してくる。またバックフォーカスが短くなりすぎローパスフィルター、赤外カットフィルターなどの光学部材を挿入するスペースを確保するのが困難になってくる。 In particular, a large amount of lateral chromatic aberration and curvature of field occur over the entire zoom range (the entire zoom range). Further, the back focus becomes too short, and it becomes difficult to secure a space for inserting an optical member such as a low-pass filter or an infrared cut filter.
条件式（１１）は第２レンズ群Ｌ２のズーミングに伴う移動距離（移動量、符号は正）を規定する式である。条件式（１１）の上限を超えて第２レンズ群Ｌ２の移動距離が長すぎるとレンズを保持するレンズ鏡筒の光軸方向の厚みが増大する。特にレンズ鏡筒が沈胴する構成の場合は沈胴長が増大し薄い撮像装置を構成することが困難になってくる。又、下限を超えて第２レンズ群Ｌ２の移動距離が短すぎると所望のズーム比（変倍比）を得るためには第２レンズ群Ｌ２の屈折力を強めなくてはならない。この場合は少ないレンズ枚数で収差補正することが難しくなり小型化と高性能化が困難になる。 Conditional expression (11) is an expression that defines the movement distance (movement amount, sign is positive) associated with zooming of the second lens unit L2. If the moving distance of the second lens unit L2 exceeds the upper limit of conditional expression (11), the thickness of the lens barrel that holds the lens in the optical axis direction increases. In particular, when the lens barrel is retracted, the retracted length increases, making it difficult to construct a thin imaging device. If the moving distance of the second lens unit L2 is too short beyond the lower limit, the refractive power of the second lens unit L2 must be strengthened in order to obtain a desired zoom ratio (magnification ratio). In this case, it is difficult to correct aberrations with a small number of lenses, and it is difficult to reduce the size and improve the performance.
条件式（１２）は第１レンズ群Ｌ１の正の第１２レンズＧ１２の焦点距離を規定する式である。条件式（１２）の上限を超えて正の第１２レンズＧ１２の焦点距離が長すぎると第１レンズ群Ｌ１としての色収差の補正が不足し、ズーム範囲全域に渡り、軸上色収差、倍率色収差が補正不足となる。又、下限を超えて正の第１２レンズＧ１２の焦点距離が短すぎると望遠側において球面収差、コマ収差の発生が多くなってくる。 Conditional expression (12) defines the focal length of the positive twelfth lens G12 of the first lens unit L1. If the focal length of the positive twelfth lens G12 exceeds the upper limit of the conditional expression (12), correction of chromatic aberration as the first lens unit L1 is insufficient, and axial chromatic aberration and lateral chromatic aberration occur over the entire zoom range. Incorrect correction. In addition, if the focal length of the positive twelfth lens G12 is too short beyond the lower limit, spherical aberration and coma will increase on the telephoto side.
条件式（１３）は第２レンズ群Ｌ２の最も物体側に配置された正の第２１レンズＧ２１の材料の屈折率を規定する式である。条件式（１３）の下限を超えて屈折率が低いとズーム範囲全域における球面収差、コマ収差の発生が多くなる。この結果、非球面を用いても良好なる補正が困難となる。更に好ましくは条件式（４）〜（１３）の数値範囲を次の如く設定するのが良い。 Conditional expression (13) defines the refractive index of the material of the positive 21st lens G21 arranged closest to the object side in the second lens unit L2. If the lower limit of conditional expression (13) is exceeded and the refractive index is low, the occurrence of spherical aberration and coma in the entire zoom range increases. As a result, even if an aspherical surface is used, good correction becomes difficult. More preferably, the numerical ranges of the conditional expressions (4) to (13) are set as follows.
−０．４＜（Ｒ１１ａ＋Ｒ１２ｂ）／（Ｒ１１ａ−Ｒ１２ｂ）≦１．０ ‥‥（４ａ）
−６．０＜（Ｒ１１ｂ＋Ｒ１２ａ）／（Ｒ１１ｂ−Ｒ１２ａ）＜−３．５‥‥（５ａ）
３５＜ν１１＜４９ ‥‥（６ａ）
１．９２＜Ｎ１２ ‥‥（７ａ）
０．４０＜｜ｆ１｜／ｆｔ＜０．５５ ‥‥（８ａ）
０．４＜ｆ２／ｆｔ＜０．５ ‥‥（９ａ）
０．７＜ｆ３／ｆｔ＜１．１ ‥‥（１０ａ）
３．７＜Ｍ２／ｆｗ＜４．８ ‥‥（１１ａ）
１．４５＜ｆ１２／｜ｆ１｜＜２．３ ‥‥（１２ａ）
１．８２＜Ｎ２１ ‥‥（１３ａ）
次に、各レンズ群のレンズ構成の具体的な特徴について説明する。実施例１乃至５において第１レンズ群Ｌ１は物体側より像側へ順に、像側の面が凹形状の負の屈折力の（負の）第１１レンズＧ１１、物体側の面が凸でメニスカス形状の正の屈折力の（正の）第１２レンズＧ１２で構成している。このような構成により第１レンズ群Ｌ１を２枚のレンズとしてレンズ系全体の小型化を図りながら諸収差を良好に補正している。
−0.4 <(R11a + R12b) / (R11a−R12b) ≦ 1.0 (4a)
−6.0 <(R11b + R12a) / (R11b−R12a) <− 3.5 (5a)
35 <ν11 <49 (6a)
1.92 <N12 (7a)
0.40 <| f1 | / ft <0.55 (8a)
0.4 <f2 / ft <0.5 (9a)
0.7 <f3 / ft <1.1 (10a)
3.7 <M2 / fw <4.8 (11a)
1.45 <f12 / | f1 | <2.3 (12a)
1.82 <N21 (13a)
Next, specific features of the lens configuration of each lens group will be described. In Examples 1 to 5, the first lens unit L1 is arranged in order from the object side to the image side, the image side surface is a negative (negative) eleventh lens G11 having a concave refractive power, the object side surface is convex, and the meniscus is It is composed of a (positive) twelfth lens G12 having a positive refractive power. With such a configuration, the first lens unit L1 is used as two lenses, and various aberrations are favorably corrected while downsizing the entire lens system.
第２レンズ群Ｌ２は物体側より像側へ順に、実施例１では物体側が凸面でメニスカス形状の正の第２１レンズＧ２１と、物体側が凸面でメニスカス形状の負の第２２レンズＧ２２とを接合した接合レンズより成っている。更に物体側が凸面でメニスカス形状の負の第２３レンズＧ２３と両凸形状の正レンズＧ２４とを接合した接合レンズより成っている。実施例２、３、４では物体側が凸面の正の第２１レンズＧ２１、物体側が凸面の正の第２２レンズＧ２２と像側が凹面の負の第２３レンズＧ２３とを接合した接合レンズ、正の第２４レンズＧ２４より成っている。 In the second lens unit L2, in order from the object side to the image side, in Example 1, a positive 21st lens G21 having a convex surface on the object side and a meniscus shape is joined to a negative 22nd lens G22 having a convex surface on the object side and a meniscus shape. It consists of a cemented lens. Further, it is composed of a cemented lens in which a negative meniscus lens G23 having a convex surface on the object side and a biconvex positive lens G24 are cemented. In Examples 2, 3, and 4, a positive 21st lens G21 having a convex surface on the object side, a positive 22nd lens G22 having a convex surface on the object side, and a negative 23rd lens G23 having a concave surface on the image side, a positive first lens It consists of 24 lenses G24.
実施例５では物体側が凸面の正の第２１レンズＧ２１と像側が凹面の負の第２２レンズＧ２２とを接合した接合レンズ、正の第２３レンズＧ２３より成っている。第２レンズ群Ｌ２を前述の如く構成することによって、色収差や軸外収差の発生を少なくし、かつ球面収差、コマ収差等を良好に補正している。第３レンズ群Ｌ３は、テレセントリック性を確保するためのフィールドレンズとしての役割を果たしており、軸上レンズ厚の短縮のため、１枚の両凸形状の正の第３１レンズＧ３１より構成している。 In the fifth exemplary embodiment, the lens includes a cemented lens obtained by cementing a positive 21st lens G21 having a convex surface on the object side and a negative 22nd lens G22 having a concave surface on the image side, and a positive 23rd lens G23. By configuring the second lens unit L2 as described above, the occurrence of chromatic aberration and off-axis aberration is reduced, and spherical aberration, coma aberration, and the like are favorably corrected. The third lens unit L3 serves as a field lens for ensuring telecentricity, and is composed of a single biconvex positive 31st lens G31 for shortening the axial lens thickness. .
次に本発明の各実施例の数値実施例を示す。各数値実施例において、ｉは物体側からの面の順序を示す。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である。ｄｉは物体側より順に第ｉ番目のレンズ厚及び空気間隔である。ｎｄｉとνｄｉは各々物体側より順に第ｉ番目の材料のガラスのｄ線に対する屈折率、アッベ数である。又前述の各条件式と数値実施例の関係を表１に示す。非球面形状は光軸方向にＸ軸、光軸と垂直方向にＨ軸、光の進行方向を正としＲを近軸曲率半径、Kを円錐定数、A4，A6，A8，A10，A12を各々非球面係数としたとき Next, numerical examples of the respective embodiments of the present invention will be shown. In each numerical example, i indicates the order of the surfaces from the object side. In the numerical examples, 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 and air spacing in order from the object side. ndi and νdi are respectively the refractive index and Abbe number for the d-line of the glass of the i-th material in order from the object side. Table 1 shows the relationship between the above-described conditional expressions and numerical examples. The aspherical shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, K is the conic constant, A4, A6, A8, A10, A12 Aspheric coefficient
なる式で表している。また、［e+X］は［×10＋ｘ］を意味し、［e-X］は［×10-ｘ］を意味している。ＢＦはレンズ最終面から近軸像面までの距離（バックフォーカス）を空気換算したものである。レンズ全長はレンズ最前面からレンズ最終面までの距離にＢＦを加えたものである。非球面は面番号の後に*を付加して示す。 It is expressed by the following formula. [E + X] means [× 10 + x], and [e-X] means [× 10-x]. BF is the air-converted distance (back focus) from the final lens surface to the paraxial image plane. The total lens length is obtained by adding BF to the distance from the lens front surface to the lens final surface. An aspherical surface is indicated by adding * after the surface number.
［数値実施例１］
単位 mm
面データ
面番号 r d nd νd
1 ∞ 1.05 1.84954 40.1
2* 5.155 1.23
3 7.963 1.70 1.94595 18.0
4 15.503 (可変)
5* 3.830 1.70 1.84954 40.1
6 35.088 0.50 1.80518 25.4
7 3.228 0.80
8 11.664 0.50 1.69895 30.1
9 5.759 2.00 1.77250 49.6
10 -22.085 0.50
11(絞り) ∞ (可変)
12 19.146 1.42 1.69680 55.5
13 -56.741 (可変)
像面 ∞
非球面データ
第2面
K = -1.67969e+000 A 4= 9.52304e-004 A 6=-6.12005e-006
A 8= 1.59433e-007 A10=-1.36767e-009 A12=0
第5面
K = -1.15224e+000 A 4= 1.76183e-003 A 6= 3.52146e-005
A 8= 1.84936e-006 A10=-6.49465e-008 A12= 1.00000e-008
各種データ
ズーム比 4.71
広角 中間 望遠
焦点距離 4.43 10.97 20.85
Fナンバー 2.94 5.14 6.00
画角 37.59 19.46 10.53
像高 3.41 3.88 3.88
レンズ全長 32.07 29.88 37.59
BF 4.19 3.88 3.42
d 4 13.00 3.30 0.17
d11 3.47 11.31 22.59
d13 4.19 3.88 3.42
ズームレンズ群データ
群 始面 焦点距離
1 1 -10.37
2 5 9.19
3 12 20.70
[Numerical Example 1]
Unit mm
Surface data surface number rd nd νd
1 ∞ 1.05 1.84954 40.1
2 * 5.155 1.23
3 7.963 1.70 1.94595 18.0
4 15.503 (variable)
5 * 3.830 1.70 1.84954 40.1
6 35.088 0.50 1.80518 25.4
7 3.228 0.80
8 11.664 0.50 1.69895 30.1
9 5.759 2.00 1.77250 49.6
10 -22.085 0.50
11 (Aperture) ∞ (Variable)
12 19.146 1.42 1.69680 55.5
13 -56.741 (variable)
Image plane ∞
Aspheric data 2nd surface
K = -1.67969e + 000 A 4 = 9.52304e-004 A 6 = -6.12005e-006
A 8 = 1.59433e-007 A10 = -1.36767e-009 A12 = 0
5th page
K = -1.15224e + 000 A 4 = 1.76183e-003 A 6 = 3.52146e-005
A 8 = 1.84936e-006 A10 = -6.49465e-008 A12 = 1.00000e-008
Various data Zoom ratio 4.71
Wide angle Medium telephoto focal length 4.43 10.97 20.85
F number 2.94 5.14 6.00
Angle of view 37.59 19.46 10.53
Image height 3.41 3.88 3.88
Total lens length 32.07 29.88 37.59
BF 4.19 3.88 3.42
d 4 13.00 3.30 0.17
d11 3.47 11.31 22.59
d13 4.19 3.88 3.42
Zoom lens group data group Start surface Focal length
1 1 -10.37
2 5 9.19
3 12 20.70
［数値実施例２］
面データ
面番号 r d nd νd
1* -80.129 1.05 1.84954 40.1
2* 5.455 1.84
3 9.481 1.70 1.92286 18.9
4 20.781 (可変)
5* 5.694 1.56 1.84954 40.1
6 72.752 0.20
7 7.145 1.10 1.69680 55.5
8 -39.682 0.40 1.80518 25.4
9 3.743 0.82
10 55.891 0.90 1.69680 55.5
11 -17.093 0.50
12(絞り) ∞ (可変)
13* 53.691 1.70 1.69350 53.2
14 -19.657 (可変)
像面 ∞
非球面データ
第1面
K = -6.85575e+001 A 4= 3.78622e-005 A 6= 2.02360e-006
A 8=-4.70081e-008 A10= 2.52815e-010 A12=0
第2面
K = -2.49393e+000 A 4= 1.44227e-003 A 6=-1.94554e-005
A 8= 6.60863e-007 A10=-1.17492e-008 A12=0
第5面
K = -2.51823e-001 A 4=-2.88572e-004 A 6=-6.45912e-006
A 8= 2.41205e-007 A10=-1.45631e-008 A12=0
第13面
K = -8.66414e+002 A 4= 4.57251e-004 A 6=-3.29303e-005
A 8= 1.21213e-006 A10=-1.83080e-008 A12=0
各種データ
ズーム比 4.72
広角 中間 望遠
焦点距離 4.42 7.64 20.85
Fナンバー 2.88 3.98 6.05
画角 37.00 26.88 10.53
像高 3.33 3.88 3.88
レンズ全長 32.56 29.36 38.45
BF 4.17 4.12 3.93
d 4 13.34 6.39 0.35
d12 3.28 7.07 22.40
d14 4.17 4.12 3.93
ズームレンズ群データ
群 始面 焦点距離
1 1 -10.07
2 5 9.22
3 13 20.95
[Numerical Example 2]
Surface data surface number rd nd νd
1 * -80.129 1.05 1.84954 40.1
2 * 5.455 1.84
3 9.481 1.70 1.92286 18.9
4 20.781 (variable)
5 * 5.694 1.56 1.84954 40.1
6 72.752 0.20
7 7.145 1.10 1.69680 55.5
8 -39.682 0.40 1.80518 25.4
9 3.743 0.82
10 55.891 0.90 1.69680 55.5
11 -17.093 0.50
12 (Aperture) ∞ (Variable)
13 * 53.691 1.70 1.69350 53.2
14 -19.657 (variable)
Image plane ∞
Aspheric data 1st surface
K = -6.85575e + 001 A 4 = 3.78622e-005 A 6 = 2.02360e-006
A 8 = -4.70081e-008 A10 = 2.52815e-010 A12 = 0
Second side
K = -2.49393e + 000 A 4 = 1.44227e-003 A 6 = -1.94554e-005
A 8 = 6.60863e-007 A10 = -1.17492e-008 A12 = 0
5th page
K = -2.51823e-001 A 4 = -2.88572e-004 A 6 = -6.45912e-006
A 8 = 2.41205e-007 A10 = -1.45631e-008 A12 = 0
Side 13
K = -8.66414e + 002 A 4 = 4.57251e-004 A 6 = -3.29303e-005
A 8 = 1.21213e-006 A10 = -1.83080e-008 A12 = 0
Various data Zoom ratio 4.72
Wide angle Medium telephoto focal length 4.42 7.64 20.85
F number 2.88 3.98 6.05
Angle of view 37.00 26.88 10.53
Image height 3.33 3.88 3.88
Total lens length 32.56 29.36 38.45
BF 4.17 4.12 3.93
d 4 13.34 6.39 0.35
d12 3.28 7.07 22.40
d14 4.17 4.12 3.93
Zoom lens group data group Start surface Focal length
1 1 -10.07
2 5 9.22
3 13 20.95
［数値実施例３］
面データ
面番号 r d nd νd
1* -40.730 1.05 1.90000 48.0
2* 6.281 2.12
3 10.941 1.70 1.94595 18.0
4 22.988 (可変)
5* 5.891 1.56 1.90000 48.0
6 61.833 0.20
7 7.014 1.10 1.69680 55.5
8 376.377 0.40 1.80518 25.4
9 3.749 0.80
10 378.272 0.90 1.69680 55.5
11 -14.946 0.50
12(絞り) ∞ (可変)
13* 47.747 1.70 1.69350 53.2
14 -16.572 (可変)
像面 ∞
非球面データ
第1面
K = -2.56017e+002 A 4= 9.66865e-005 A 6= 1.86470e-006
A 8=-5.59595e-008 A10= 3.31152e-010 A12=0
第2面
K = -2.50216e+000 A 4= 1.42822e-003 A 6=-2.45712e-005
A 8= 9.94260e-007 A10=-1.78646e-008 A12=0
第5面
K = -2.34319e-001 A 4=-3.16178e-004 A 6=-6.54470e-006
A 8= 7.77388e-007 A10=-4.10861e-008 A12=0
第13面
K = -6.59795e+002 A 4= 3.95186e-004 A 6=-3.30974e-005
A 8= 1.21213e-006 A10=-1.83080e-008 A12=0
各種データ
ズーム比 4.75
広角 中間 望遠
焦点距離 4.02 7.03 19.10
Fナンバー 2.73 3.81 6.06
画角 39.65 28.88 11.47
像高 3.33 3.88 3.88
レンズ全長 32.22 29.16 38.63
BF 4.00 4.02 3.92
d 4 13.05 6.19 0.42
d12 3.12 6.91 22.24
d14 4.00 4.02 3.92
ズームレンズ群データ
群 始面 焦点距離
1 1 -9.35
2 5 9.04
3 13 17.93
[Numerical Example 3]
Surface data surface number rd nd νd
1 * -40.730 1.05 1.90000 48.0
2 * 6.281 2.12
3 10.941 1.70 1.94595 18.0
4 22.988 (variable)
5 * 5.891 1.56 1.90000 48.0
6 61.833 0.20
7 7.014 1.10 1.69680 55.5
8 376.377 0.40 1.80518 25.4
9 3.749 0.80
10 378.272 0.90 1.69680 55.5
11 -14.946 0.50
12 (Aperture) ∞ (Variable)
13 * 47.747 1.70 1.69350 53.2
14 -16.572 (variable)
Image plane ∞
Aspheric data 1st surface
K = -2.56017e + 002 A 4 = 9.66865e-005 A 6 = 1.86470e-006
A 8 = -5.59595e-008 A10 = 3.31152e-010 A12 = 0
Second side
K = -2.50216e + 000 A 4 = 1.42822e-003 A 6 = -2.45712e-005
A 8 = 9.94260e-007 A10 = -1.78646e-008 A12 = 0
5th page
K = -2.34319e-001 A 4 = -3.16178e-004 A 6 = -6.54470e-006
A 8 = 7.77388e-007 A10 = -4.10861e-008 A12 = 0
Side 13
K = -6.59795e + 002 A 4 = 3.95186e-004 A 6 = -3.30974e-005
A 8 = 1.21213e-006 A10 = -1.83080e-008 A12 = 0
Various data Zoom ratio 4.75
Wide angle Medium Telephoto focal length 4.02 7.03 19.10
F number 2.73 3.81 6.06
Angle of view 39.65 28.88 11.47
Image height 3.33 3.88 3.88
Total lens length 32.22 29.16 38.63
BF 4.00 4.02 3.92
d 4 13.05 6.19 0.42
d12 3.12 6.91 22.24
d14 4.00 4.02 3.92
Zoom lens group data group Start surface Focal length
1 1 -9.35
2 5 9.04
3 13 17.93
［数値実施例４］
面データ
面番号 r d nd νd
1* -20.005 1.05 1.83000 42.0
2* 7.031 2.02
3 11.901 1.70 1.92286 18.9
4 35.445 (可変)
5* 5.460 1.56 1.83000 42.0
6 2137.403 0.20
7 7.682 1.10 1.69680 55.5
8 -41.260 0.40 1.80518 25.4
9 3.553 0.82
10 25.890 0.90 1.69680 55.5
11 -57.751 0.50
12(絞り) ∞ (可変)
13* 45.596 1.70 1.69350 53.2
14 -15.839 (可変)
像面 ∞
非球面データ
第1面
K = -4.91130e+001 A 4= 9.27734e-005 A 6= 2.92261e-006
A 8=-8.67939e-008 A10= 5.40258e-010 A12=0
第2面
K = -2.36588e+000 A 4= 1.34626e-003 A 6=-2.27576e-005
A 8= 9.43910e-007 A10=-1.87509e-008 A12=0
第5面
K = -2.55556e-001 A 4=-3.61259e-004 A 6=-7.91650e-006
A 8= 4.71901e-007 A10=-3.04645e-008 A12=0
第13面
K = -4.08129e+002 A 4= 4.18136e-004 A 6=-3.33793e-005
A 8= 1.21214e-006 A10=-1.83080e-008 A12=0
各種データ
ズーム比 4.47
広角 中間 望遠
焦点距離 4.44 7.43 19.85
Fナンバー 2.83 3.86 6.10
画角 36.89 27.54 11.05
像高 3.33 3.88 3.88
レンズ全長 33.63 30.45 39.13
BF 4.22 4.15 3.92
d 4 14.12 7.23 0.80
d12 3.33 7.13 22.46
d14 4.22 4.15 3.92
ズームレンズ群データ
群 始面 焦点距離
1 1 -10.64
2 5 9.77
3 13 17.15
[Numerical Example 4]
Surface data surface number rd nd νd
1 * -20.005 1.05 1.83000 42.0
2 * 7.031 2.02
3 11.901 1.70 1.92286 18.9
4 35.445 (variable)
5 * 5.460 1.56 1.83000 42.0
6 2137.403 0.20
7 7.682 1.10 1.69680 55.5
8 -41.260 0.40 1.80518 25.4
9 3.553 0.82
10 25.890 0.90 1.69680 55.5
11 -57.751 0.50
12 (Aperture) ∞ (Variable)
13 * 45.596 1.70 1.69350 53.2
14 -15.839 (variable)
Image plane ∞
Aspheric data 1st surface
K = -4.91130e + 001 A 4 = 9.27734e-005 A 6 = 2.92261e-006
A 8 = -8.67939e-008 A10 = 5.40258e-010 A12 = 0
Second side
K = -2.36588e + 000 A 4 = 1.34626e-003 A 6 = -2.27576e-005
A 8 = 9.43910e-007 A10 = -1.87509e-008 A12 = 0
5th page
K = -2.55556e-001 A 4 = -3.61259e-004 A 6 = -7.91650e-006
A 8 = 4.71901e-007 A10 = -3.04645e-008 A12 = 0
Side 13
K = -4.08129e + 002 A 4 = 4.18136e-004 A 6 = -3.33793e-005
A 8 = 1.21214e-006 A10 = -1.83080e-008 A12 = 0
Various data Zoom ratio 4.47
Wide angle Medium telephoto focal length 4.44 7.43 19.85
F number 2.83 3.86 6.10
Angle of view 36.89 27.54 11.05
Image height 3.33 3.88 3.88
Total lens length 33.63 30.45 39.13
BF 4.22 4.15 3.92
d 4 14.12 7.23 0.80
d12 3.33 7.13 22.46
d14 4.22 4.15 3.92
Zoom lens group data group Start surface Focal length
1 1 -10.64
2 5 9.77
3 13 17.15
［数値実施例５］
単位 mm
面データ
面番号 r d nd νd
1* -51.347 1.05 1.84954 40.1
2* 6.285 1.61
3 9.383 1.90 2.20000 17.0
4 14.794 (可変)
5* 4.321 1.70 2.00000 40.0
6 26.092 0.50 1.80809 22.8
7 3.296 0.60
8* 13.224 1.30 1.77250 49.6
9* -22.061 0.50
10(絞り) ∞ (可変)
11 17.492 1.42 1.69680 55.5
12 -66.105 (可変)
像面 ∞
非球面データ
第1面
K = -5.52558e+002 A 4= 1.17613e-004 A 6= 1.69941e-006
A 8=-6.18420e-008 A10= 4.01512e-010 A12=0
第2面
K = -1.68185e+000 A 4= 1.17631e-003 A 6=-1.82191e-005
A 8= 9.43969e-007 A10=-1.81545e-008 A12=0
第5面
K = -1.08494e+000 A 4= 1.06827e-003 A 6= 1.19765e-005
A 8= 7.99367e-007 A10=-3.06143e-009 A12= 1.00000e-008
第8面
K = 1.23124e+001 A 4= 4.58023e-009 A 6= 4.58023e-011
A 8= 4.58023e-013 A10= 4.58023e-015 A12=0
第9面
K = 1.56985e+001 A 4= 5.15497e-004 A 6=-4.33305e-005
A 8= 6.72224e-013 A10= 6.72224e-015 A12=0
各種データ
ズーム比 4.63
広角 中間 望遠
焦点距離 4.55 13.23 21.07
Fナンバー 2.88 5.46 7.78
画角 36.88 16.32 10.42
像高 3.41 3.88 3.88
レンズ全長 32.72 31.09 37.50
BF 3.60 3.58 3.56
d 4 13.64 2.46 0.29
d10 4.91 14.48 23.08
d12 3.60 3.58 3.56
ズームレンズ群データ
群 始面 焦点距離
1 1 -10.67
2 5 9.23
3 11 19.99
前述の各条件式と数値実施例における諸数値の関係を表１に示す
[Numerical Example 5]
Unit mm
Surface data surface number rd nd νd
1 * -51.347 1.05 1.84954 40.1
2 * 6.285 1.61
3 9.383 1.90 2.20000 17.0
4 14.794 (variable)
5 * 4.321 1.70 2.00000 40.0
6 26.092 0.50 1.80809 22.8
7 3.296 0.60
8 * 13.224 1.30 1.77250 49.6
9 * -22.061 0.50
10 (Aperture) ∞ (Variable)
11 17.492 1.42 1.69680 55.5
12 -66.105 (variable)
Image plane ∞
Aspheric data 1st surface
K = -5.52558e + 002 A 4 = 1.17613e-004 A 6 = 1.69941e-006
A 8 = -6.18420e-008 A10 = 4.01512e-010 A12 = 0
Second side
K = -1.68185e + 000 A 4 = 1.17631e-003 A 6 = -1.82191e-005
A 8 = 9.43969e-007 A10 = -1.81545e-008 A12 = 0
5th page
K = -1.08494e + 000 A 4 = 1.06827e-003 A 6 = 1.19765e-005
A 8 = 7.99367e-007 A10 = -3.06143e-009 A12 = 1.00000e-008
8th page
K = 1.23124e + 001 A 4 = 4.58023e-009 A 6 = 4.58023e-011
A 8 = 4.58023e-013 A10 = 4.58023e-015 A12 = 0
9th page
K = 1.56985e + 001 A 4 = 5.15497e-004 A 6 = -4.33305e-005
A 8 = 6.72224e-013 A10 = 6.72224e-015 A12 = 0
Various data Zoom ratio 4.63
Wide angle Medium telephoto focal length 4.55 13.23 21.07
F number 2.88 5.46 7.78
Angle of view 36.88 16.32 10.42
Image height 3.41 3.88 3.88
Total lens length 32.72 31.09 37.50
BF 3.60 3.58 3.56
d 4 13.64 2.46 0.29
d10 4.91 14.48 23.08
d12 3.60 3.58 3.56
Zoom lens group data group Start surface Focal length
1 1 -10.67
2 5 9.23
3 11 19.99
Table 1 shows the relationship between the above conditional expressions and various numerical values in the numerical examples.
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）の実施例を図１１を用いて説明する。図１１において、２０はカメラ本体、２１は本発明のズームレンズによって構成された撮影光学系である。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）である。２３は撮像素子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である。 Next, an embodiment of a digital still camera (image pickup apparatus) using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG. In FIG. 11, reference numeral 20 denotes a camera body, and 21 denotes a photographing optical system constituted by the zoom lens of the present invention. Reference numeral 22 denotes a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor that receives a subject image formed by the photographing optical system 21 and is built in the camera body. A memory 23 records information corresponding to the subject image photoelectrically converted by the image sensor 22.
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ーである。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を実現している。 Reference numeral 24 is a finder for observing a subject image formed on the solid-state image sensor 22, which includes a liquid crystal display panel or the like. Thus, by applying the zoom lens of the present invention to an image pickup apparatus such as a digital still camera, a small image pickup apparatus having high optical performance is realized.
Ｌ１ 第１レンズ群、 Ｌ２ 第２レンズ群、 Ｌ３ 第３レンズ群、
ＳＰ Ｆナンバー決定部材（開口絞り）、 ＩＰ 像面、 Ｇ ガラスブロック、
ｄ ｄ線、 ｇ ｇ線、 ΔＳ サジタル像面、 ΔＭ メリディオナル像面
L1 first lens group, L2 second lens group, L3 third lens group,
SP F number determining member (aperture stop), IP image plane, G glass block,
d d line, g g line, ΔS sagittal image plane, ΔM meridional image plane
Claims (12)
１．８１＜Ｎ１１
ν１２＜１９
０＜（Ｒ１１ａ＋Ｒ１１ｂ）／（Ｒ１１ａ−Ｒ１１ｂ）≦１．０
−７．０＜（Ｒ１１ｂ＋Ｒ１２ａ）／（Ｒ１１ｂ−Ｒ１２ａ）＜−３．０
０．３＜｜ｆ１｜／ｆｔ＜０．６
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 to the image side, a first lens unit having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power are arranged, and each lens group is moved for zooming. In the zoom lens to be performed, the first lens group includes, in order from the object side to the image side, an eleventh lens having a negative refractive power and a twelfth lens having a positive refractive power, and the refractive index of the material of the eleventh lens is determined. N11, the Abbe number of the material of the twelfth lens is ν12, the curvature radii of the object-side and image-side lens surfaces of the eleventh lens are R11a and R11b, respectively, and the radius of curvature of the object-side lens surface of the twelfth lens is R1a, when the focal length of the first lens unit is f1, and the focal length of the entire system at the telephoto end is ft, 1.81 <N11
ν12 <19
0 <(R11a + R11b) / (R11a−R11b) ≦ 1.0
−7.0 <(R11b + R12a) / (R11b−R12a) <− 3.0
0.3 <| f1 | / ft <0.6
A zoom lens characterized by satisfying the following conditions:
３０＜ν１１＜５０
１．９０＜Ｎ１２
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。 When the Abbe number of the material of the eleventh lens is ν11 and the refractive index of the material of the twelfth lens is N12, 30 <ν11 <50
1.90 <N12
The zoom lens according to claim 1, wherein the following condition is satisfied.
０．３＜ｆ２／ｆｔ＜０．６
なる条件を満足することを特徴とする請求項１又は２に記載のズームレンズ。 When the focal length of the second lens group is f2, 0.3 <f2 / ft <0.6
The zoom lens according to claim 1, wherein the following condition is satisfied.
０．６＜ｆ３／ｆｔ＜１．２
なる条件を満足す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。 When the focal length of the third lens group is f3, 0.6 <f3 / ft <1.2
The zoom lens according to claim 1, wherein the following condition is satisfied.
３．５＜Ｍ２／ｆｗ＜５．０
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。 In the zooming from the wide angle end to the telephoto end, the moving distance in the optical axis direction of the second lens group is M2, and the focal length of the entire system at the wide angle end is fw. 3.5 <M2 / fw <5.0
The zoom lens according to claim 1, wherein the following condition is satisfied.
１．４＜ｆ１２／｜ｆ１｜＜２．５
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 twelfth lens is f12, 1.4 <f12 / | f1 | <2.5
The zoom lens according to claim 1, wherein the following condition is satisfied.
１．８＜Ｎ２１
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。 The second lens group has a 21st lens having a positive refractive power and a convex surface on the object side closest to the object side. When the refractive index of the material of the 21st lens is N21, 1.8 < N21
The zoom lens according to claim 1, wherein the following condition is satisfied.
１．８１＜Ｎ１１
ν１２＜１９
０＜（Ｒ１１ａ＋Ｒ１１ｂ）／（Ｒ１１ａ−Ｒ１１ｂ）≦１．０
３．５＜Ｍ２／ｆｗ＜５．０
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 to the image side, a first lens unit having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power are arranged, and each lens group is moved for zooming. In the zoom lens to be performed, the first lens group includes, in order from the object side to the image side, an eleventh lens having a negative refractive power and a twelfth lens having a positive refractive power, and the refractive index of the material of the eleventh lens is determined. N11, Abbe number of the material of the twelfth lens is ν12, curvature radii of the object-side and image-side lens surfaces of the eleventh lens are R11a and R11b, respectively, and the second lens group in zooming from the wide-angle end to the telephoto end Where M2 is the moving distance in the optical axis direction, and fw is the focal length of the entire system at the wide angle end, 1.81 <N11
ν12 <19
0 <(R11a + R11b) / (R11a−R11b) ≦ 1.0
3.5 <M2 / fw <5.0
A zoom lens characterized by satisfying the following conditions:
１．８１＜Ｎ１１
ν１２＜１９
０＜（Ｒ１１ａ＋Ｒ１１ｂ）／（Ｒ１１ａ−Ｒ１１ｂ）≦１．０
−６．０＜（Ｒ１１ｂ＋Ｒ１２ａ）／（Ｒ１１ｂ−Ｒ１２ａ）＜−３．５
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 to the image side, a first lens unit having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power are arranged, and each lens group is moved for zooming. In the zoom lens to be performed, the first lens group includes, in order from the object side to the image side, an eleventh lens having a negative refractive power and a twelfth lens having a positive refractive power, and the refractive index of the material of the eleventh lens is determined. N11, the Abbe number of the material of the twelfth lens is ν12, the curvature radii of the object-side and image-side lens surfaces of the eleventh lens are R11a and R11b, respectively, and the radius of curvature of the object-side lens surface of the twelfth lens is When R12a, 1.81 <N11
ν12 <19
0 <(R11a + R11b) / (R11a−R11b) ≦ 1.0
−6.0 <(R11b + R12a) / (R11b−R12a) <− 3.5
A zoom lens characterized by satisfying the following conditions:
１．８１＜Ｎ１１
ν１２＜１９
０＜（Ｒ１１ａ＋Ｒ１１ｂ）／（Ｒ１１ａ−Ｒ１１ｂ）≦１．０
１．８２＜Ｎ２１
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 to the image side, a first lens unit having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power are arranged, and each lens group is moved for zooming. In the zoom lens to be performed, the first lens group includes, in order from the object side to the image side, an eleventh lens having a negative refractive power and a twelfth lens having a positive refractive power, and the second lens group is closest to the object side. Further, the object-side surface has a 21st lens having a positive refractive power and a positive refractive power, the refractive index of the material of the 11th lens is N11, the Abbe number of the material of the 12th lens is ν12, and the 11th lens 1.81 <N11 where R11a and R11b are the radii of curvature of the object-side and image-side lens surfaces, and N21 is the refractive index of the 21st lens material.
ν12 <19
0 <(R11a + R11b) / (R11a−R11b) ≦ 1.0
1.82 <N21
A zoom lens characterized by satisfying the following conditions:
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010091948A (en) * | 2008-10-10 | 2010-04-22 | Olympus Imaging Corp | Zoom lens and imaging apparatus having the same |
| JP2010134373A (en) * | 2008-12-08 | 2010-06-17 | Olympus Imaging Corp | Image pickup apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010091948A (en) * | 2008-10-10 | 2010-04-22 | Olympus Imaging Corp | Zoom lens and imaging apparatus having the same |
| JP2010134373A (en) * | 2008-12-08 | 2010-06-17 | Olympus Imaging Corp | Image pickup apparatus |
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