JP2001066503A - Zoom lens - Google Patents
Zoom lensInfo
- Publication number
- JP2001066503A JP2001066503A JP24527399A JP24527399A JP2001066503A JP 2001066503 A JP2001066503 A JP 2001066503A JP 24527399 A JP24527399 A JP 24527399A JP 24527399 A JP24527399 A JP 24527399A JP 2001066503 A JP2001066503 A JP 2001066503A
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- Japan
- Prior art keywords
- lens
- group
- positive
- negative
- refractive power
- Prior art date
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Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、ズームレンズに関
し、特に負の屈折力のレンズ群が先行する全体として3
つのレンズ群を有し、これらの各レンズ群のレンズ構成
を適切に設定することにより、レンズ系全体の小型化を
図ったフィルム用のスチルカメラやビデオカメラ、そし
てデジタルスチルカメラ等に好適な広画角のズームレン
ズに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens, and more particularly to a zoom lens system in which a lens unit having a negative refractive power precedes the zoom lens system.
By setting the lens configuration of each of these lens groups appropriately, a wide-angle lens suitable for film still cameras, video cameras, digital still cameras, etc., with the overall size of the lens system reduced. The present invention relates to a zoom lens having an angle of view.
【0002】[0002]
【従来の技術】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、撮像装置(カメラ)の高
機能化にともない、それに用いる光学系には高性能で小
型のズームレンズが求められている。この種のカメラに
は、レンズ最後部と撮像素子との間に、ローパスフィル
ターや色補正フィルターなどの各種光学部材を配置する
為、それに用いる光学系には、比較的バックフォーカス
の長いレンズ系が要求される。さらに、カラー画像用の
撮像素子を用いたカラーカメラの場合、色シェーディン
グを避けるため、それに用いる光学系には像側のテレセ
ントリック特性の良いものが望まれている。2. Description of the Related Art Recently, with the advancement of functions of an imaging device (camera) such as a video camera and a digital still camera using a solid-state imaging device, a high-performance and small-sized zoom lens is required for an optical system used therein. I have. In this type of camera, various optical members such as a low-pass filter and a color correction filter are arranged between the rearmost part of the lens and the image pickup device. Required. Further, in the case of a color camera using an image pickup device for a color image, in order to avoid color shading, an optical system used therefor is desired to have good image-side telecentric characteristics.
【0003】従来より、負の屈折力の第1群と正の屈折
力の第2群の2つのレンズ群より成り、双方のレンズ間
隔を変えて変倍を行う。所謂ショートズームタイプの広
角の2群ズームレンズが種々提案されている。これらの
ショートズームタイプの光学系では、正の屈折力の第2
群を移動することで変倍を行い、負の屈折力の第1群を
移動することで変倍に伴う像点位置の補正を行ってい
る。Conventionally, there are two lens groups, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and the magnification is changed by changing the distance between both lenses. Various types of so-called short zoom type wide-angle two-unit zoom lenses have been proposed. In these short zoom type optical systems, the second system having a positive refractive power
The zooming is performed by moving the group, and the image point position accompanying the zooming is corrected by moving the first group having a negative refractive power.
【0004】これらの2つのレンズ群よりなるレンズ構
成においては、ズーム倍率は2倍程度である。さらに2
倍以上の高い変倍比を有しつつレンズ全体をコンパクト
な形状にまとめるため、例えば特公平7-3507号公報や、
特公平6-40170 号公報等には2群ズームレンズの像側に
負または正の屈折力の第3群を配置し、高倍化に伴って
発生する諸収差の補正を行っている、所謂3群ズームレ
ンズが提案されている。[0004] In a lens configuration composed of these two lens groups, the zoom magnification is about twice. 2 more
To combine the entire lens into a compact shape while having a high zoom ratio of 2 times or more, for example, Japanese Patent Publication No. 7-3507,
In Japanese Patent Publication No. 6-40170, a third lens unit having a negative or positive refractive power is arranged on the image side of a two-unit zoom lens to correct various aberrations caused by increasing the magnification. Group zoom lenses have been proposed.
【0005】しかしながら、これらの3群ズームレンズ
は主として35mmフィルム写真用に設計されているた
め、固体撮像素子を用いた光学系に求められるバックフ
ォーカスの長さと、良好なテレセントリック特性を両立
したものとは言い難かった。However, since these three-group zoom lenses are designed mainly for 35 mm film photography, they have both a back focus length required for an optical system using a solid-state image sensor and good telecentric characteristics. Was hard to say.
【0006】[0006]
【発明が解決しようとする課題】バックフォーカスとテ
レセントリック特性を満足する広角の3群ズームレンズ
系が、例えば、特開昭63-135913 号公報や、特開平7-26
1083号公報等で提案されている。また、特開平3-288113
号公報には、3群ズームレンズにおいて負の屈折力の第
1群を固定とし、正の屈折力の第2群と正の屈折力の第
3群を移動させて変倍を行う光学系も開示されている。
ところが、これらの従来例においては、各レンズ群の構
成枚数が比較的多く、レンズ全長が長い、製造コストが
高いなどの欠点を有していた。A wide-angle three-unit zoom lens system satisfying the back focus and telecentric characteristics is disclosed in, for example, JP-A-63-135913 and JP-A-7-26.
It is proposed in, for example, Japanese Patent Publication No. 1083. Also, JP-A-3-288113
In Japanese Patent Laid-Open Publication No. H10-207, there is also provided an optical system in which a first group having a negative refractive power is fixed and a second group having a positive refractive power and a third group having a positive refractive power are moved to perform zooming. It has been disclosed.
However, in these conventional examples, there are disadvantages such as a relatively large number of components in each lens group, a long overall lens length, and a high manufacturing cost.
【0007】また、特開平7-261083号公報に記載される
例では、負の屈折力の第1群のもっとも物体側に凸レン
ズ(正レンズ)が配置されており、特に広角化した場合
のレンズ外径の増大が避けられない欠点を有していた。
さらに、この例では負の屈折力の第1群を移動させて近
距離物体へのフォーカシングを行うため、ズーミングで
の移動とあいまってメカ構造の複雑化する欠点があっ
た。In the example described in Japanese Patent Application Laid-Open No. Hei 7-261083, a convex lens (positive lens) is arranged closest to the object side of the first lens unit having a negative refractive power. There was a disadvantage that an increase in outer diameter was inevitable.
Further, in this example, since the first group having negative refractive power is moved to perform focusing on a short-distance object, there is a disadvantage that the mechanical structure is complicated together with the movement during zooming.
【0008】また、米国特許第4,999,007 号公報には、
3群ズームレンズにおいて、第1レンズ群、第2レンズ
群をそれぞれ1枚の単レンズで構成したものも開示され
ている。ところが、広角端でのレンズ全長が比較的大き
く、さらに広角端での第1 群と絞りが大きく離れている
ため軸外光線の入射高が大きく第1群を構成するレンズ
の径が増大してしまうため、レンズ系全体が大きくなっ
てしまう欠点を有していた。Further, US Pat. No. 4,999,007 discloses that
There is also disclosed a three-group zoom lens in which the first lens group and the second lens group are each configured by one single lens. However, the overall length of the lens at the wide-angle end is relatively large, and since the stop is far away from the first lens group at the wide-angle end, the incident height of off-axis rays is large and the diameter of the lens constituting the first lens group increases. Therefore, there is a disadvantage that the entire lens system becomes large.
【0009】また、第1群、第2群は構成枚数が1枚の
ため群内における収差補正が不十分であった。特に変倍
時の倍率色収差の変動は軸外光線の光軸の高さの変動が
大きい第1群内にて発生しやすいが、第1群を凹レンズ
の1枚としているので群内での補正がされておらず、全
系においても倍率色収差変動が大きいという課題を有す
る。Further, the first and second lens units have only one component, so that the aberration correction in the lens units is insufficient. In particular, the fluctuation of the chromatic aberration of magnification at the time of zooming is likely to occur in the first group where the fluctuation of the height of the optical axis of the off-axis light beam is large. However, since the first group is one concave lens, correction within the group is performed. However, there is a problem that the chromatic aberration of magnification is large even in the entire system.
【0010】さらに、ズーム広角端での画角を大きくし
た場合の特有な問題として歪曲収差の補正不足の問題が
ある。また、 比較的感度の低い高画素の撮影素子で用い
るためには更なる大口径比化が求められる。Further, as a specific problem when the angle of view at the zoom wide-angle end is increased, there is a problem of insufficient correction of distortion. Further, a larger aperture ratio is required for use in a high-sensitivity imaging device having relatively low sensitivity.
【0011】さらに、本出願人は特願平10-301684号公
報において負−正−正の屈折力の3つのレンズ群より成
る3群構成の撮影レンズを開示している。この撮影レン
ズではフィルター等を挿入するために必要なレンズバッ
クの確保と、固体撮像素子用として必要なテレセントリ
ック特性を両立した上で、極力全長を短縮しコンパクト
なズームレンズを達成している。Further, the present applicant has disclosed in Japanese Patent Application No. 10-301684 a photographic lens having a three-group configuration including three lens groups having negative, positive and positive refractive powers. This photographing lens achieves a compact zoom lens by shortening the overall length as much as possible while ensuring both a lens back necessary for inserting a filter and the like and a telecentric characteristic required for a solid-state imaging device.
【0012】一方、近年の固体撮像素子は多画素化が進
んでおり、特定のイメージサイズにおける画素サイズは
小さくなる傾向にある。これに伴い撮影レンズには同じ
イメージサイズの従来のものに比べてより高い空間周波
数での解像力向上が求められている。特願平10-301684
号公報で開示しているレンズ構成においては全系の収斂
作用の大部分を担う第2群を物体側から順に正負正の所
謂トリプレットで構成しており、諸収差の補正と小型化
を両立している。On the other hand, in recent years, the number of pixels in a solid-state imaging device has been increased, and the pixel size in a specific image size tends to be smaller. Accordingly, a photographing lens is required to have higher resolution at a higher spatial frequency than a conventional lens having the same image size. Japanese Patent Application No. 10-301684
In the lens configuration disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, the second group, which is responsible for most of the convergence action of the entire system, is composed of a positive / negative / positive so-called triplet in order from the object side, thereby achieving both correction of various aberrations and miniaturization. ing.
【0013】本発明では、本出願人は先に提案した特開
平10-301684号公報で開示しているズームレンズを更に
改良し、固体撮像素子を用いた撮影系に好適な、構成レ
ンズ枚数の少ない、コンパクトで、小径化を達成した高
変倍比で、特に色収差が良好に補正され、優れた光学性
能を有するズームレンズの提供を目的とする。In the present invention, the present applicant has further improved the zoom lens disclosed in Japanese Patent Application Laid-Open No. 10-301684, which has been proposed above, and has a number of constituent lenses suitable for a photographing system using a solid-state image sensor. It is an object of the present invention to provide a zoom lens that is small, compact, has a high zoom ratio with a reduced diameter, and has particularly good chromatic aberration correction and excellent optical performance.
【0014】[0014]
【課題を解決するための手段】請求項1の発明のズーム
レンズは、物体側より順に負の屈折力の第1群、正の屈
折力の第2群、そして正の屈折力の第3群を有し、広角
端から望遠端への変倍時に第1群と第2群との間隔が縮
まり、第2群と第3群との間隔が広がるズームレンズに
おいて、該第1群は像面側に凹面を向けたメニスカス状
の負レンズ、物体側に凸面を向けたメニスカス状の正レ
ンズを有し、該第2群は最も像面側に負レンズと正レン
ズより構成され全体として正の屈折力の接合レンズA
と、該接合レンズAより物体側のレンズ中最も像面側の
レンズBは像面側のレンズ面が像面側に凹面を向けた形
状であることを特徴としている。According to a first aspect of the present invention, there is provided a zoom lens having a first unit having a negative refractive power, a second unit having a positive refractive power, and a third unit having a positive refractive power. Wherein the distance between the first group and the second group is reduced at the time of zooming from the wide-angle end to the telephoto end, and the distance between the second group and the third group is widened. A negative meniscus lens having a concave surface on the side, and a positive meniscus lens having a convex surface on the object side. The second group is composed of a negative lens and a positive lens closest to the image surface side, and has a positive lens as a whole. Refractive power cemented lens A
The lens B closest to the image plane among the lenses closer to the object side than the cemented lens A is characterized in that the lens surface on the image plane side has a concave surface facing the image plane side.
【0015】請求項2の発明は請求項1の発明におい
て、前記第2群中の接合レンズAの焦点距離をfc、前
記第2群の焦点距離をf2、前記接合レンズAの物体側
のレンズ面の曲率半径をRa、前記レンズBの像面側の
レンズ面の曲率半径をRbとしたとき、 0.5<fc/f2<2.0 0.5<(Ra+Rb)/(Ra−Rb)<2.5 の条件式を満足することを特徴としている。According to a second aspect of the present invention, in the first aspect, the focal length of the cemented lens A in the second group is fc, the focal length of the second group is f2, and the object-side lens of the cemented lens A is When the radius of curvature of the surface is Ra and the radius of curvature of the lens surface on the image surface side of the lens B is Rb, 0.5 <fc / f2 <2.0 0.5 <(Ra + Rb) / (Ra-Rb) <2.5 is satisfied.
【0016】請求項3の発明は請求項2の発明におい
て、前記第2群は物体側より順に物体側に凸面を向けた
正レンズ、像面側に凹面を向けた負レンズ、そして接合
レンズを有することを特徴としている。According to a third aspect of the present invention, in the second aspect, the second group includes, in order from the object side, a positive lens having a convex surface facing the object side, a negative lens having a concave surface facing the image surface side, and a cemented lens. It is characterized by having.
【0017】請求項4の発明のズームレンズは、物体側
より順に負の屈折力の第1群、正の屈折力の第2群、そ
して正の屈折力の第3群を有し、広角端から望遠端への
変倍時に第1群と第2群との間隔は縮まり、第2群と第
3群との間隔は広がるズームレンズにおいて、該第1群
は像面側に凹面を向けたメニスカス状の負レンズ、物体
側に凸面を向けたメニスカス状の正レンズを有し、該第
2群は両レンズ面が凹面の負レンズと、該負レンズより
物体側に配置され、物体側に凸面を向けた正レンズ、さ
らに該負レンズより像面側に配置され負レンズと正レン
ズより構成され、全体として正の屈折力の接合レンズを
有することを特徴としている。A zoom lens according to a fourth aspect of the present invention has, in order from the object side, a first unit having a negative refractive power, a second unit having a positive refractive power, and a third unit having a positive refractive power. The distance between the first and second groups is reduced at the time of zooming from the zoom lens to the telephoto end, and the distance between the second and third groups is increased. In the zoom lens, the first group has a concave surface facing the image plane side. The second group includes a meniscus-shaped negative lens, a meniscus-shaped positive lens having a convex surface facing the object side, and the second group is disposed on the object side with respect to the negative lens having both concave lens surfaces and on the object side. It is characterized by having a positive lens with a convex surface, and a negative lens and a positive lens disposed on the image side of the negative lens and having a cemented lens having a positive refractive power as a whole.
【0018】請求項5の発明は請求項4の発明におい
て、前記第2群中の負レンズの焦点距離をfn、前記第
2群の焦点距離をf2、前記第2群中の最も物体側に配
置され物体側に凸面を向けた正レンズの物体側のレンズ
面の曲率半径をRc、像面側のレンズ面の曲率半径をR
dとしたとき、 0.3<|fn|/f2<2.0 0<(Rd+Rc)/(Rd−Rc)<2.5 の条件式を満足することを特徴としている。According to a fifth aspect of the present invention, in the fourth aspect, the focal length of the negative lens in the second group is fn, the focal length of the second group is f2, and the focal length of the negative lens in the second group is closest to the object side. The radius of curvature of the lens surface on the object side of the positive lens having the convex surface facing the object side is Rc, and the radius of curvature of the lens surface on the image surface side is R.
When d, 0.3 <| fn | / f2 <2.00 <(Rd + Rc) / (Rd-Rc) <2.5 is satisfied.
【0019】請求項6の発明は請求項3又は5の発明に
おいて、前記第3群は正レンズ1枚、もしくは正レンズ
と負レンズで構成され全体として正の接合レンズで構成
されることを特徴としている。According to a sixth aspect of the present invention, in the third or fifth aspect, the third unit is constituted by one positive lens or a positive cemented lens as a whole, comprising a positive lens and a negative lens. And
【0020】請求項7の発明は請求項3又は5の発明に
おいて、前記第1群中の負レンズの中の少なくとも1つ
のレンズ面は非球面であり、該非球面は光軸から周辺に
向かってしだいに発散作用が弱まる形状であることを特
徴としている。According to a seventh aspect of the present invention, in the third or fifth aspect, at least one lens surface of the negative lenses in the first group is an aspheric surface, and the aspheric surface extends from the optical axis toward the periphery. It is characterized in that the divergence gradually weakens.
【0021】請求項8の発明は請求項3又は5の発明に
おいて、前記第2群中の正レンズ中の少なくとも1つの
レンズ面は非球面であり、該非球面は光軸から周辺に向
かってしだいに収斂作用が弱まる形状であることを特徴
としている。According to an eighth aspect of the present invention, in the third or fifth aspect, at least one lens surface of the positive lens in the second group is an aspherical surface, and the aspherical surface increases from the optical axis toward the periphery. It is characterized in that the shape is such that the convergence action is weakened.
【0022】請求項9の発明は請求項3又は5の発明に
おいて、前記第3群は正レンズを有し、該正レンズの少
なくとも1つのレンズ面は非球面であり、該非球面は光
軸から周辺に向かってしだいに収斂作用が弱まる形状で
あることを特徴としている。According to a ninth aspect of the present invention, in the third or fifth aspect, the third unit has a positive lens, at least one lens surface of the positive lens is an aspherical surface, and the aspherical surface is located away from the optical axis. It is characterized in that the convergence effect gradually weakens toward the periphery.
【0023】請求項10の発明は請求項3又は5の発明
において、前記第3群は変倍に際して移動することを特
徴としている。A tenth aspect of the present invention is characterized in that, in the third or fifth aspect, the third lens unit moves upon zooming.
【0024】請求項11の発明のズームレンズは、物体
側より順に負の屈折力の第1群、正の屈折力の第2群、
そして正の屈折力の第3群を有し、広角端から望遠端へ
の変倍時に第1群と第2群との間隔は縮まり、第2群と
第3群との間隔は広がるズームレンズにおいて、第1群
は像面側に凹面を向けたメニスカス状の負レンズ、物体
側に凸面を向けたメニスカス状の正レンズを有し、該第
2群は物体側より順に1つ又は2つの正レンズと、両レ
ンズ面が凹面の負レンズB、そして負レンズと正レンズ
との接合レンズAとを有し、前記第2群中の接合レンズ
Aの焦点距離をfc、前記第2群の焦点距離をf2、前
記接合レンズAの物体側のレンズ面の曲率半径をRa、
前記レンズBの像側面の曲率半径をRb、前記第2群中
のレンズBの焦点距離をfn、前記第2群中の最も物体
側に配置され物体側に凸面を向けた正レンズの物体側面
の曲率半径をRc、像面側のレンズ面の曲率半径をRd
としたとき、 0.5<fc/f2<2.0 0.5<(Ra+Rb)/(Ra−Rb)<2.5 0.3<|fn|/f2<2.0 0<(Rd+Rc)/(Rd−Rc)<2.5 の条件式を満足するよう構成されたことを特徴としてい
る。In the zoom lens according to the eleventh aspect of the present invention, the first group having a negative refractive power, the second group having a positive refractive power,
A zoom lens having a third lens unit having a positive refractive power, wherein the distance between the first lens unit and the second lens unit is reduced and the distance between the second lens unit and the third lens unit is widened during zooming from the wide-angle end to the telephoto end. In the first group, a meniscus-shaped negative lens having a concave surface facing the image surface side, a meniscus-shaped positive lens having a convex surface facing the object side, and the second group has one or two lenses in order from the object side. It has a positive lens, a negative lens B with both lens surfaces concave, and a cemented lens A of a negative lens and a positive lens, the focal length of the cemented lens A in the second group being fc, The focal length is f2, the radius of curvature of the lens surface on the object side of the cemented lens A is Ra,
The radius of curvature of the image side surface of the lens B is Rb, the focal length of the lens B in the second group is fn, and the object side surface of the positive lens of the second group which is disposed closest to the object side and has a convex surface facing the object side. Is the radius of curvature of Rc, and the radius of curvature of the lens surface on the image side is Rd.
0.5 <fc / f2 <2.0 0.5 <(Ra + Rb) / (Ra-Rb) <2.5 0.3 <| fn | / f2 <2.00 <(Rd + Rc) /(Rd-Rc)<2.5.
【0025】[0025]
【発明の実施の形態】図1は本発明の後述する数値実施
例1のレンズ断面図である。図2〜図4は本発明の数値
実施例の広角端,中間,望遠端の収差図である。FIG. 1 is a lens sectional view of a numerical example 1 of the present invention described later. 2 to 4 are aberration diagrams at the wide-angle end, at the middle, and at the telephoto end in a numerical example of the present invention.
【0026】図5は本発明の後述する数値実施例2のレ
ンズ断面図である。図6〜図8は本発明の数値実施例の
広角端,中間,望遠端の収差図である。FIG. 5 is a sectional view of a lens according to a second numerical example of the present invention. 6 to 8 are aberration diagrams at a wide-angle end, a middle position, and a telephoto end in a numerical example of the present invention.
【0027】図9は本発明の後述する数値実施例3のレ
ンズ断面図である。図10〜図12は本発明の数値実施
例の広角端,中間,望遠端の収差図である。FIG. 9 is a sectional view of a lens according to a third numerical example of the present invention, which will be described later. FIGS. 10 to 12 are aberration diagrams at the wide-angle end, at the middle, and at the telephoto end in the numerical examples of the present invention.
【0028】図13は本発明の後述する数値実施例4の
レンズ断面図である。図14〜図16は本発明の数値実
施例の広角端,中間,望遠端の収差図である。FIG. 13 is a sectional view of a lens according to a fourth numerical example of the present invention, which will be described later. FIGS. 14 to 16 are aberration diagrams at the wide-angle end, at the middle, and at the telephoto end in the numerical examples of the present invention.
【0029】図17は本発明の後述する数値実施例5の
レンズ断面図である。図18〜図20は本発明の数値実
施例の広角端,中間,望遠端の収差図である。FIG. 17 is a sectional view of a lens according to a fifth numerical example of the present invention, which will be described later. FIGS. 18 to 20 are aberration diagrams at the wide-angle end, at the middle, and at the telephoto end, respectively, in the numerical examples of the present invention.
【0030】レンズ断面図においてL1は負の屈折力の
第1群(第1レンズ群)、L2は正の屈折力の第2群
(第2レンズ群)、L3は正の屈折力の第3群(第3レ
ンズ群)、SPは開口絞り、IPは像面である。Gはフ
ィルターや色分解プリズム等のガラスブロックである。In the sectional view of the lens, L1 is a first group (first lens group) having a negative refractive power, L2 is a second group (second lens group) having a positive refractive power, and L3 is a third group having a positive refractive power. A group (third lens group), SP denotes an aperture stop, and IP denotes an image plane. G is a glass block such as a filter or a color separation prism.
【0031】本発明のズームレンズの基本構成は、負の
屈折力の第1群と正の屈折力の第2群とで所謂広角ショ
ートズーム系を構成しており、正の屈折力の第2群の移
動により変倍を行い、負の屈折力の第1群を往復移動に
よって変倍に伴う像点の移動を補正している。正の屈折
力の第3群はズーミング中固定の場合、変倍には寄与し
ないが、撮像素子の小型化に伴う撮影レンズの屈折力の
増大を分担し、第1,第2群で構成されるショートズー
ム系の屈折力を減らすことで、特に第1群を構成する各
レンズでの収差の発生を抑え、良好な光学性能を達成し
ている。また、特に固体撮像素子等を用いた撮影装置に
必要な像側のテレセントリックな結像を正の屈折力の第
3群をフィールドレンズの役割を持たせることで達成し
ている。また、第3群がズーミング中移動する場合は、
第3群に入射する軸外光線の光軸の高さをコントロール
できるため、軸外諸収差に対する補正能力が高まり、変
倍全域に渡ってさらに良好な性能を実現している。In the basic configuration of the zoom lens of the present invention, a first group having a negative refractive power and a second group having a positive refractive power constitute a so-called wide-angle short zoom system. The magnification is changed by moving the group, and the movement of the image point accompanying the magnification is corrected by reciprocating the first group having a negative refractive power. The third unit having a positive refractive power does not contribute to zooming when fixed during zooming, but shares an increase in the refractive power of the photographing lens with the downsizing of the image sensor, and is composed of the first and second units. By reducing the refractive power of the short zoom system, it is possible to suppress the occurrence of aberration particularly in each lens constituting the first group, thereby achieving good optical performance. In particular, telecentric imaging on the image side required for a photographing apparatus using a solid-state imaging device or the like is achieved by providing the third lens unit having a positive refractive power as a field lens. If the third group moves during zooming,
Since the height of the optical axis of the off-axis ray entering the third lens group can be controlled, the ability to correct various off-axis aberrations is increased, and better performance is achieved over the entire zoom range.
【0032】また、絞りSPを第2群内の物体側に置
き、広角側での入射瞳と第1群との距離を縮めること
で、第1群を構成するレンズの外径の増大をおさえると
ともに、正の屈折力の第2群の物体側に配置した絞りを
挟んで第1群と第3群とで軸外の諸収差を打ち消すこと
で構成レンズ枚数を増やさずに良好な光学性能を得てい
る。Further, the stop SP is placed on the object side in the second lens unit, and the distance between the entrance pupil and the first lens unit on the wide-angle side is reduced, so that the outer diameter of the lens constituting the first lens unit can be prevented from increasing. In addition, good optical performance can be achieved without increasing the number of constituent lenses by canceling various off-axis aberrations in the first and third units with a stop disposed on the object side of the second unit having a positive refractive power interposed therebetween. It has gained.
【0033】本発明は前述の基本構成の基で、 (1-1)第1発明は、該第1群は像面側に凹面を向けたメ
ニスカス状の負レンズ、物体側に凸面を向けたメニスカ
ス状の正レンズを有し、該第2群は最も像面側に負レン
ズと正レンズより構成され全体として正の屈折力の接合
レンズAと、該接合レンズAより物体側のレンズ中最も
像面側のレンズBは像面側のレンズ面が像面側に凹面を
向けた形状であることを特徴としている。The present invention is based on the basic structure described above. (1-1) In the first invention, the first group is a meniscus negative lens having a concave surface facing the image surface side, and having a convex surface facing the object side. The second group includes a negative lens and a positive lens closest to the image surface side, and has a cemented lens A having a positive refractive power as a whole, and the most lens among the lenses closer to the object side than the cemented lens A. The lens B on the image plane side is characterized in that the lens surface on the image plane side has a concave surface facing the image plane side.
【0034】尚、第1発明において更に好ましくは次の
条件のうち少なくとも1つを満足させるのが良い。In the first invention, it is more preferable to satisfy at least one of the following conditions.
【0035】(ア-1)前記第2群中の接合レンズAの焦点
距離をfc、前記第2群の焦点距離をf2、前記接合レ
ンズAの物体側のレンズ面の曲率半径をRa、前記レン
ズBの像面側のレンズ面の曲率半径をRbとしたとき、 0.5<fc/f2<2.0…(1) 0.5<(Ra+Rb)/(Ra−Rb)<2.5…(2) の条件式を満足することである。(A-1) The focal length of the cemented lens A in the second group is fc, the focal length of the second group is f2, the radius of curvature of the object-side lens surface of the cemented lens A is Ra, When the radius of curvature of the lens surface on the image surface side of the lens B is Rb, 0.5 <fc / f2 <2.0 (1) 0.5 <(Ra + Rb) / (Ra−Rb) <2.5 .. (2) must be satisfied.
【0036】(ア-2)前記第2群は物体側より順に物体側
に凸面を向けた正レンズ、像面側に凹面を向けた負レン
ズ、そして接合レンズを有することである。(A-2) The second group includes, in order from the object side, a positive lens having a convex surface facing the object side, a negative lens having a concave surface facing the image surface side, and a cemented lens.
【0037】(1-2)第2発明は、該第1群は像面側に凹
面を向けたメニスカス状の負レンズ、物体側に凸面を向
けたメニスカス状の正レンズを有し、該第2群は両レン
ズ面が凹面の負レンズと、該負レンズより物体側に配置
され、物体側に凸面を向けた正レンズ、さらに該負レン
ズより像面側に配置され負レンズと正レンズより構成さ
れ、全体として正の屈折力の接合レンズを有することを
特徴としている。(1-2) In the second invention, the first group has a meniscus-shaped negative lens having a concave surface facing the image surface side and a meniscus-shaped positive lens having a convex surface facing the object side. The second group includes a negative lens having both concave lens surfaces, a positive lens disposed on the object side of the negative lens, and having a convex surface facing the object side, and a negative lens and a positive lens disposed on the image surface side of the negative lens. It is characterized by having a cemented lens having a positive refractive power as a whole.
【0038】尚、第2発明において更に好ましくは次の
条件のうちの少なくとも1つを満足させるのが良い。In the second aspect, it is more preferable that at least one of the following conditions be satisfied.
【0039】(イ-1)前記第2群中の負レンズの焦点距離
をfn、前記第2群の焦点距離をf2、前記第2群中の
最も物体側に配置され物体側に凸面を向けた正レンズの
物体側のレンズ面の曲率半径をRc、像面側のレンズ面
の曲率半径をRdとしたとき、 0.3<|fn|/f2<2.0…(3) 0<(Rd+Rc)/(Rd−Rc)<2.5…(4) の条件式を満足することである。(A-1) The focal length of the negative lens in the second lens unit is fn, the focal length of the second lens unit is f2, and the convex surface of the second lens unit which is disposed closest to the object side and faces the object side. When the radius of curvature of the lens surface on the object side of the positive lens is Rc, and the radius of curvature of the lens surface on the image side is Rd, 0.3 <| fn | / f2 <2.0 (3) 0 <( Rd + Rc) / (Rd-Rc) <2.5 (4)
【0040】(イ-2)前記第3群は正レンズ1枚、もしく
は正レンズと負レンズで構成され全体として正の接合レ
ンズで構成されることである。(A-2) The third unit is composed of one positive lens or a positive lens and a negative lens, and is composed of a positive cemented lens as a whole.
【0041】(1-3)第1群は像面側に凹面を向けたメニ
スカス状の負レンズ、物体側に凸面を向けたメニスカス
状の正レンズを有し、該第2群は物体側より順に1つ又
は2つの正レンズと、両レンズ面が凹面の負レンズB、
そして負レンズと正レンズとの接合レンズAとを有し、
前記第2群中の接合レンズAの焦点距離をfc、前記第
2群の焦点距離をf2、前記接合レンズAの物体側のレ
ンズ面の曲率半径をRa、前記レンズBの像側面の曲率
半径をRb、前記第2群中のレンズBの焦点距離をf
n、前記第2群中の最も物体側に配置され物体側に凸面
を向けた正レンズの物体側面の曲率半径をRc、像面側
のレンズ面の曲率半径をRdとしたとき、 0.5<fc/f2<2.0…(1) 0.5<(Ra+Rb)/(Ra−Rb)<2.5…(2) 0.3<|fn|/f2<2.0…(3) 0<(Rd+Rc)/(Rd−Rc)<2.5…(4) の条件式を満足するよう構成されたことである。(1-3) The first group has a meniscus negative lens with a concave surface facing the image surface side, and a meniscus positive lens with a convex surface facing the object side. One or two positive lenses in order and a negative lens B with both lens surfaces concave,
And a cemented lens A of a negative lens and a positive lens,
The focal length of the cemented lens A in the second group is fc, the focal length of the second lens group is f2, the radius of curvature of the object-side lens surface of the cemented lens A is Ra, and the radius of curvature of the image side surface of the lens B is Is Rb, and the focal length of the lens B in the second group is f
n, where Rc is the radius of curvature of the object side surface of the positive lens with the convex surface facing the object side in the second group and closest to the object side, and Rd is the radius of curvature of the lens surface on the image side. <Fc / f2 <2.0 (1) 0.5 <(Ra + Rb) / (Ra-Rb) <2.5 (2) 0.3 <| fn | / f2 <2.0 (3) 0 <(Rd + Rc) / (Rd−Rc) <2.5 (4)
【0042】次に各発明の特徴について説明する。尚、
第1,第2,第3発明を総称して「本発明」ともいう。Next, the features of each invention will be described. still,
The first, second, and third inventions are also collectively referred to as “the present invention”.
【0043】本発明のズームレンズは、負の屈折力の第
1群を物体側から順に物体側に凸面を向けたメニスカス
状の負レンズと物体側に凸面を向けたメニスカス状の正
レンズの2つのレンズより構成し、または第1群を2枚
の像側に凹面を向けた凹レンズ(負レンズ)11、凹レ
ンズ12、そして物体側に凸面を向けた凸レンズ(正レ
ンズ)13の3枚で構成している。また、正の屈折力の
第2群を物体側から順に物体側に凸面を向けた凸レンズ
21、両レンズ面が凹面の凹レンズ22、負レンズと正
レンズより成る接合レンズ23の3群4枚構成で構成
し、または、第2群を物体側より順に2つの正レンズ、
両レンズ面が凹面の負レンズ22、負レンズと正レンズ
より成る接合レンズ23の4群5枚で構成している。The zoom lens according to the present invention includes a first lens unit having a negative refractive power, a meniscus negative lens having a convex surface facing the object side in order from the object side, and a meniscus positive lens having a convex surface facing the object side. The first group is composed of three lenses: a concave lens (negative lens) 11 having a concave surface facing the image side, a concave lens 12, and a convex lens (positive lens) 13 having a convex surface facing the object side. are doing. The second lens group having a positive refractive power has a convex lens 21 having a convex surface facing the object side in order from the object side, a concave lens 22 having both lens surfaces concave, and a cemented lens 23 including a negative lens and a positive lens. Or the second group is composed of two positive lenses in order from the object side,
It comprises four groups and five negative lenses 22, both of which have concave surfaces, and a cemented lens 23 composed of a negative lens and a positive lens.
【0044】正の屈折力の第3群を凸レンズ1枚または
正レンズと負レンズとの接合レンズで構成している。こ
のように各群を所望の屈折力配置を収差補正とを両立す
る構成とすることにより、良好な性能を保ちつつ、レン
ズ系のコンパクト化を達成している。The third group having a positive refractive power comprises one convex lens or a cemented lens of a positive lens and a negative lens. As described above, by making each unit a desired refractive power arrangement compatible with aberration correction, a compact lens system is achieved while maintaining good performance.
【0045】負の屈折力の第1群は、軸外主光線を絞り
中心に瞳結像させる役割を持っており、特に広角側にお
いては軸外主光線の屈折量が大きいために軸外諸収差、
特に非点収差と歪曲収差が発生しやすい。そこで、通常
の広角レンズと同様に最も物体側のレンズ径の増大が抑
えられる凹−凸の構成とした上で、主に負の屈折力を分
担している2つの負レンズ11,12で屈折力の分担を
図っている。第1群を構成する各レンズは、軸外主光線
の屈折によって生じる軸外収差の発生を抑えるために絞
り中心を中心とする同心球面に近い形状をとっている。
すなわち、負レンズ11,12は像面に凹面を向けたメ
ニスカス形状とし、正レンズ13は物体側に凸面を向け
たメニスカス形状としている。The first group having a negative refractive power has a role of forming a pupil image of the off-axis principal ray at the center of the stop. Particularly on the wide-angle side, the amount of refraction of the off-axis principal ray is large. aberration,
In particular, astigmatism and distortion tend to occur. Therefore, similarly to a normal wide-angle lens, a concave-convex configuration in which an increase in the lens diameter closest to the object side is suppressed, and the two negative lenses 11 and 12, which mainly share negative refractive power, perform refraction. They are trying to share power. Each lens constituting the first group has a shape close to a concentric spherical surface centered on the stop center in order to suppress the occurrence of off-axis aberration caused by the refraction of the off-axis principal ray.
That is, the negative lenses 11 and 12 have a meniscus shape with the concave surface facing the image plane, and the positive lens 13 has a meniscus shape with the convex surface facing the object side.
【0046】正の屈折力の第2群は、両レンズ面が凹面
の凹レンズ22の前後に正レンズを配置し、屈折力配置
上において対称的な構成としている。これは、変倍中大
きく移動する群であることから、製造誤差による群相互
の偏心等による製造劣化を未然に防ぐため、群単体で球
面収差、コマ収差等をある程度取り除いたものとするた
めである。The second group having a positive refractive power has a positive lens disposed before and after the concave lens 22 having both concave lens surfaces, and has a symmetric configuration in terms of the refractive power arrangement. This is because the group moves greatly during zooming, and in order to prevent manufacturing deterioration due to eccentricity of the groups due to manufacturing errors, etc., it is necessary to remove spherical aberration, coma, etc. to some extent by the group alone. is there.
【0047】第2群中のもっとも物体側の凸レンズ21
は第1群を射出した軸外主光線が大きく屈折して軸外諸
収差が発生しないよう物体側に凸の形状にしている。ま
た、第1群を発散状態で射出した軸上光束に対して球面
収差の発生量を抑えるためにも凸レンズ21は物体側に
凸の形状としている。The most object-side convex lens 21 in the second group
Has a shape that is convex toward the object side so that off-axis chief rays emitted from the first lens unit do not refract greatly and do not generate off-axis aberrations. The convex lens 21 has a convex shape on the object side in order to suppress the amount of spherical aberration generated with respect to the on-axis light flux emitted from the first lens unit in a divergent state.
【0048】さらに、凹レンズ22は物体側と像面とも
に凹面とし、前後の凸レンズ21と正の接合レンズ23
とともに負の空気レンズを形成し、大口径比化に伴って
発生する球面収差と、コマ収差の補正を良好に行ってい
る。Further, the concave lens 22 has a concave surface on both the object side and the image surface, and the front and rear convex lenses 21 and the positive cemented lens 23
In addition, a negative air lens is formed, so that spherical aberration and coma aberration generated with a large aperture ratio are corrected well.
【0049】さらに凹レンズ22の像面側に接合レンズ
23を配置して色収差を良好に補正している。本発明の
ズームレンズの構成では第1群にて軸外光束が屈曲する
高さは広角端で高く、望遠端で低くなるため、変倍に伴
う倍率色収差の変動は特に第1群にて発生する。そこ
で、第1群の屈折力配置および硝材選択は特に倍率色収
差の変動が最小となるように構成している。第1群をコ
ンパクトにするために前述のように凹−凸の構成とし
て、構成枚数を2から3枚程度とした場合、第1群内に
て軸上色収差の変動成分が残存しやすい。そこで第2群
内に接合レンズを用いることで軸上色収差を良好に補正
している。Further, a cemented lens 23 is disposed on the image plane side of the concave lens 22 to correct chromatic aberration well. In the configuration of the zoom lens of the present invention, the off-axis luminous flux in the first group has a high bending angle at the wide-angle end and a low height at the telephoto end, so that variation in chromatic aberration of magnification due to zooming occurs particularly in the first group. I do. Therefore, the refractive power arrangement and the selection of the glass material in the first group are configured so that the fluctuation of the chromatic aberration of magnification is minimized. In the case where the number of constituent members is about two to three as the concave-convex structure as described above in order to make the first group compact, a fluctuation component of axial chromatic aberration tends to remain in the first group. Therefore, axial chromatic aberration is favorably corrected by using a cemented lens in the second group.
【0050】また、少しでも倍率色収差の補正を第2群
内にも分担させるには接合レンズを絞りより離れた位置
に配置するのが効果的であるため、本発明では凹レンズ
22の像側に配置している。Further, it is effective to arrange the cemented lens at a position farther from the stop in order to at least partially correct the chromatic aberration of magnification in the second lens unit. Have been placed.
【0051】正の屈折力の第3群は、物体側に凸面を設
けた形状の凸レンズより構成し、または正レンズと負レ
ンズとの接合レンズより構成し、像側がテレセントリッ
ク系となるようにしている。また、フィールドレンズと
しての役割も有するようにしている。The third unit having a positive refractive power is constituted by a convex lens having a convex surface on the object side, or a cemented lens of a positive lens and a negative lens so that the image side is telecentric. I have. Further, it also has a role as a field lens.
【0052】また、各レンズ群を少ない枚数で構成しつ
つ、更なる光学性能の向上を達成するため、本実施例で
は非球面を効果的に導入している。In this embodiment, an aspherical surface is effectively introduced in order to further improve the optical performance while configuring each lens unit with a small number of lenses.
【0053】図1に示す数値実施例1においては、第1
群を構成する凹レンズ11の像側面を周辺で発散作用が
弱くなる形状の非球面とし、特に広角側での像面彎曲、
非点収差および歪曲収差の補正を行い変倍に伴う収差変
動を低減している。In Numerical Embodiment 1 shown in FIG.
The image side surface of the concave lens 11 constituting the group is formed as an aspherical surface having a shape in which the diverging effect is weak at the periphery, and particularly, the image surface curvature on the wide angle side,
Astigmatism and distortion are corrected to reduce aberration fluctuation due to zooming.
【0054】また、第2群を構成する凸レンズ21の物
体側のレンズ面を周辺で収斂作用が弱くなる非球面とし
ており、大口径化で顕著になる球面収差の補正を効果的
におこなっている。The lens surface on the object side of the convex lens 21 constituting the second lens unit is formed as an aspheric surface having a weak convergence function in the periphery, and effectively corrects spherical aberration which becomes conspicuous with a large aperture. .
【0055】また、第3群を構成する凸レンズ31の物
体側のレンズ面を周辺で収斂作用が弱くなる非球面とし
ており、変倍全域での像面彎曲、非点収差、歪曲収差の
補正を効果的におこなっている。Further, the lens surface on the object side of the convex lens 31 constituting the third lens unit is formed as an aspheric surface having a weak convergence function at the periphery, and corrects curvature of field, astigmatism, and distortion over the entire zoom range. We are doing it effectively.
【0056】本実施例のズームレンズを用いて近距離物
体を撮影する場合には、第1群を物体側へ移動すること
で良好な性能を得られるが、第3群を物体側に移動する
リアフォーカス式を用いても良い。これによれば、フォ
ーカシングによる前玉径の増大が防げる、また、最短撮
像距離が短縮でき、フォーカス群が軽量化できるといっ
たメリットが得られる。When photographing an object at a short distance using the zoom lens of this embodiment, good performance can be obtained by moving the first lens unit to the object side, but moving the third lens unit to the object side. A rear focus type may be used. According to this, it is possible to prevent the diameter of the front lens from increasing due to focusing, to shorten the minimum imaging distance, and to reduce the weight of the focus group.
【0057】次に前述の各条件式の技術的意味について
説明する。Next, the technical meaning of each of the above conditional expressions will be described.
【0058】条件式(1)は第2群の接合レンズの屈折
力を規定している式である。本発明の第2群は前述にあ
るように、正,負,正の屈折力の対称型な屈折力配置と
している。上記接合レンズの屈折力は第2群の像側の正
の屈折力を担っており、第2群の屈折力と比してある範
囲内にあるのが好ましい。Conditional expression (1) defines the refractive power of the cemented lens of the second group. As described above, the second group of the present invention has a symmetrical refractive power arrangement of positive, negative, and positive refractive powers. The refractive power of the cemented lens has a positive refractive power on the image side of the second group, and is preferably within a certain range as compared with the refractive power of the second group.
【0059】条件式(1)の上限を越えて接合レンズの
屈折力が弱まると、第2群に必要な収斂作用をもたせる
には第2群中の物体側の正レンズの屈折力を強めなけれ
ばならず、過度の球面収差が発生し非球面を用いても補
正不足となるため良くない。また、物体側の正レンズの
屈折力を強めない場合は第2群の屈折力自体が弱まるた
め、変倍のための移動量が大きくなり、レンズ全長、前
玉径の増大を招きコンパクトなズームレンズが構成でき
なくなるためよくない。When the refractive power of the cemented lens is weakened beyond the upper limit of the conditional expression (1), the refractive power of the positive lens on the object side in the second group must be increased in order to provide the necessary convergence action for the second group. However, excessive spherical aberration occurs, and even if an aspherical surface is used, correction will be insufficient, which is not good. If the refractive power of the positive lens on the object side is not increased, the refractive power of the second lens unit itself is weakened, so that the amount of movement for zooming is increased, and the overall length of the lens and the diameter of the front lens are increased, resulting in a compact zoom. This is not good because the lens cannot be configured.
【0060】また、条件式(1)の下限を超えて接合レ
ンズの屈折力が強まると、第2群内のペッツバール和が
正方向に大きくなり、アンダーの像面彎曲が発生するた
め良くない。また、軸上色収差を補正するために接合レ
ンズ面の曲率をきつくしなければならず、接合レンズを
構成する正レンズのコバ厚を確保するために中心肉厚が
大きくなりコンパクト化の点で良くない。If the refractive power of the cemented lens exceeds the lower limit of the conditional expression (1), the Petzval sum in the second lens unit becomes large in the positive direction, which is not good because an under field curvature occurs. In addition, the curvature of the cemented lens surface must be tight in order to correct longitudinal chromatic aberration, and the center thickness is large in order to secure the edge thickness of the positive lens that constitutes the cemented lens, which is good in terms of compactness. Absent.
【0061】条件式(2)は第2群の像側に配置された
接合レンズとその直前の凹レンズとで構成される負の屈
折力の空気レンズの形状因子を規定している式である。The conditional expression (2) defines the shape factor of the air lens having a negative refractive power and composed of the cemented lens disposed on the image side of the second lens unit and the concave lens immediately before the cemented lens.
【0062】第2群中の絞りを物体側に配置すると第2
群の物体側の正レンズの物体側のレンズ面と凹レンズの
物体側のレンズ面とで同符合のコマ収差が発生する。こ
れに対して空気レンズの物体側のレンズ面はこれらとは
異符号のコマ収差が、像側のレンズ面は同符合のコマ収
差が発生するため、空気レンズの物体側のレンズ面を像
側に凹面を向けた状態で曲率をある程度きつくし、これ
とは反対に空気レンズの像側のレンズ面は比較的緩い曲
率とするとコマ収差に対して補正効果がある。尚、形状
因子が1より大きいとメニスカス形状、1より小さいと
両凸レンズであり、像側のレンズ面の曲率半径は1より
大きくなるにつれ像側に曲率中心を持ちながら小さくな
り、反対に1より小さくなるにつれ物体側に曲率中心を
持ちながら曲率が小さくなる。When the stop in the second group is arranged on the object side, the second
The same coma aberration occurs between the object-side lens surface of the positive lens on the object side of the group and the object-side lens surface of the concave lens. On the other hand, the object side lens surface of the air lens has a coma of the opposite sign, and the image side lens surface has the same sign of the same coma. If the curvature is made to some extent in a state where the concave surface is directed toward the lens, and the lens surface on the image side of the air lens has a relatively gentle curvature, on the contrary, there is an effect of correcting coma. When the shape factor is larger than 1, the lens has a meniscus shape, and when the shape factor is smaller than 1, it is a biconvex lens. As the radius of curvature of the lens surface on the image side becomes larger than 1, it becomes smaller while having a center of curvature on the image side. As the size becomes smaller, the curvature becomes smaller while having the center of curvature on the object side.
【0063】条件式(2)の上限を超えて空気レンズの
メニスカスの度合いが強まると空気レンズの像側のレン
ズ面の曲率が強くなりすぎ、空気レンズのコマ収差の補
正能力が弱まる。結果として第2群はコマ収差が補正不
足となるため良くない。If the upper limit of the conditional expression (2) is exceeded and the degree of meniscus of the air lens increases, the curvature of the lens surface on the image side of the air lens becomes too strong, and the ability of the air lens to correct coma aberration decreases. As a result, the second group is not good because coma is undercorrected.
【0064】空気レンズの形状因子が1より小さくなる
と空気レンズの像側のレンズ面は物体側に曲率中心を持
つため、空気レンズは両凸形状となる。これに伴い像側
の接合レンズはメニスカス形状となる。接合レンズが条
件式(1)を満足する屈折力を有するためには接合レン
ズの像側のレンズ面の曲率がきつくなってしまう。条件
式(2)の下限値を超えると、結果的に接合レンズの像
側のレンズ面の曲率がきつくなりすぎ、アンダーの球面
収差が発生し非球面を用いても補正不足となるため良く
ない。If the shape factor of the air lens is smaller than 1, the image surface of the air lens has a center of curvature on the object side, so that the air lens has a biconvex shape. Accordingly, the cemented lens on the image side has a meniscus shape. In order for the cemented lens to have a refractive power satisfying the conditional expression (1), the curvature of the lens surface on the image side of the cemented lens becomes tight. If the lower limit value of the conditional expression (2) is exceeded, the curvature of the lens surface on the image side of the cemented lens will become too tight as a result, causing under-spherical aberration and insufficient correction even if an aspherical surface is used. .
【0065】条件式(3)は第2群の両レンズ面が凹面
の負レンズの屈折力を規定している式である。Conditional expression (3) is an expression that defines the refractive power of a negative lens having both concave surfaces in the second group.
【0066】条件式(3)の上限を超えて屈折力が弱ま
ると第2群内のペッツバール和が正方向に大きくなりア
ンダーの像面彎曲が発生するため良くない。また、フィ
ルター群を配置するための十分なバックフォーカスが得
られない。更に、射出瞳を像面から十分遠ざけることが
できないといった問題が発生する。If the refractive power is weakened beyond the upper limit of the conditional expression (3), the Petzval sum in the second lens unit becomes large in the positive direction, which causes an under-surface curvature, which is not good. Also, a sufficient back focus for arranging the filter group cannot be obtained. Further, there arises a problem that the exit pupil cannot be sufficiently moved away from the image plane.
【0067】条件式(3)の下限を超えて屈折力が強ま
ると球面収差が補正過剰となる、オーバーの像面彎曲が
発生する、バックフォーカスが長くなりすぎコンパクト
化が困難となるため良くない。If the refractive power exceeds the lower limit of conditional expression (3), the spherical aberration will be overcorrected, the field curvature will be excessive, and the back focus will be too long, and it will be difficult to make it compact, which is not good. .
【0068】条件式(4)は第2群中の物体側の正レン
ズの形状因子を規定した式である。Conditional expression (4) defines the shape factor of the positive lens on the object side in the second lens unit.
【0069】条件式(4)の上限を超え、像側のレンズ
面の曲率が像側に曲率中心を有しながら状態できつくな
ると、特にコマ収差の発生が顕著になり、非球面を用い
ても補正困難となるため良くない。When the value exceeds the upper limit of the conditional expression (4) and the curvature of the lens surface on the image side becomes tight with the center of curvature on the image side, coma aberration particularly becomes remarkable, and an aspherical surface is used. Is also not good because the correction becomes difficult.
【0070】条件式(4)の下限を超え、像側のレンズ
面の曲率が物体側に曲率中心を有しながらきつくなると
軸上ランド光線の像側面への入射角がきつくなりすぎア
ンダーの球面収差が発生するため良くない。If the lower limit of conditional expression (4) is exceeded and the curvature of the lens surface on the image side becomes tight while having the center of curvature on the object side, the incident angle of the axial land ray on the image side surface becomes too tight and the under-spherical surface It is not good because aberration occurs.
【0071】以下に、本発明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し、R
iは第i面の曲率半径、Diは第i面と第i+1面との
間のレンズ肉厚又は空気間隔、Ni,νiはそれぞれd
線に対する屈折率、アッベ数を示す。また、もっとも像
側の2面は水晶ローパスフィルター、赤外カットフィル
ター等のフィルター部材である。また、B,C,D,
E,Fは非球面係数である。非球面形状は光軸からの高
さhの位置での光軸方向の変位を面頂点を基準にしてx
とするとき、 x=R{1−(1−h2/R2)1/2}+Bh4+Ch6+
Dh8+Eh10+Fh12で表される。但しRは曲率半径
である。「e−0X」は「10-X」を意味している。ま
た、前述の各条件式と数値実施例における諸数値との関
係を表1に示す。Hereinafter, numerical examples of the present invention will be described. In each numerical example, i indicates the order of the surface from the object side, and R
i is the radius of curvature of the i-th surface, Di is the lens thickness or air gap between the i-th surface and the (i + 1) -th surface, and Ni and νi are d, respectively.
The refractive index and Abbe number for the line are shown. The two surfaces closest to the image side are filter members such as a quartz low-pass filter and an infrared cut filter. B, C, D,
E and F are aspheric coefficients. The aspherical shape is obtained by calculating the displacement in the optical axis direction at a position of height h from the optical axis with respect to the surface vertex as x
When a, x = R {1- (1 -h 2 / R 2) 1/2} + Bh 4 + Ch 6 +
It is represented by Dh 8 + Eh 10 + Fh 12 . Here, R is a radius of curvature. “E-0X” means “10 −X ”. Table 1 shows the relationship between the above-described conditional expressions and various numerical values in the numerical examples.
【0072】[数値実施例1]本数値実施例の断面図を
図1に、広角端,中間位置,望遠端での収差図を図2,
3,4に示す。[Numerical Embodiment 1] FIG. 1 is a sectional view of this numerical embodiment, and FIG. 2 is an aberration diagram at the wide-angle end, an intermediate position, and a telephoto end.
3 and 4.
【0073】本実施例は物体側から順に正の屈折力の第
1群、負の屈折力の第2群、正の屈折力の第3群で構成
され、広角端から望遠端へのズーミングに際し、第1群
は像側に凸状の往復運動、第2群は物体側へ移動、第3
群は像側へ移動する。以下レンズデータを示す。This embodiment comprises, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power. The zooming from the wide-angle end to the telephoto end is performed. The first group moves reciprocally to the image side, the second group moves to the object side, and the third group moves to the object side.
The group moves to the image side. The lens data is shown below.
【0074】[0074]
【外1】 [Outside 1]
【0075】[数値実施例2]本実施例の断面図を図5
に、広角端,中間位置,望遠端での収差図を図6,7,
8に示す。[Numerical Embodiment 2] FIG. 5 is a sectional view of this embodiment.
The aberration diagrams at the wide-angle end, the intermediate position, and the telephoto end are shown in FIGS.
FIG.
【0076】本実施例は物体側から順に正の屈折力の第
1群、負の屈折力の第2群、正の屈折力の第3群で構成
され、広角端から望遠端へのズーミングに際し、第1群
は像側に凸状の往復運動、第2群は物体側へ移動、第3
群は像側へ移動する。以下レンズデータを示す。This embodiment comprises, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power. The zooming from the wide-angle end to the telephoto end is performed. The first group moves reciprocally to the image side, the second group moves to the object side, and the third group moves to the object side.
The group moves to the image side. The lens data is shown below.
【0077】[0077]
【外2】 [Outside 2]
【0078】[数値実施例3]本実施例の断面図を図9
に、広角端,中間位置,望遠端での収差図を図10,1
1,12に示す。[Numerical Embodiment 3] A sectional view of this embodiment is shown in FIG.
FIGS. 10 and 1 show aberration diagrams at the wide-angle end, the intermediate position, and the telephoto end.
1 and 12.
【0079】本実施例は物体側から順に正の屈折力の第
1群、負の屈折力の第2群、正の屈折力の第3群で構成
され、広角端から望遠端へのズーミングに際し、第1群
は像側に凸状の往復運動、第2群は物体側へ移動、第3
群は像側へ移動する。This embodiment is composed of, in order from the object side, a first unit having a positive refractive power, a second unit having a negative refractive power, and a third unit having a positive refractive power. When zooming from the wide-angle end to the telephoto end, zooming is performed. The first group moves reciprocally to the image side, the second group moves to the object side, and the third group moves to the object side.
The group moves to the image side.
【0080】本実施例が数値実施例1と異なるのは、第
1群の構成枚数を2枚とした点である。本実施例では像
側に凹面を向けたメニスカス状の負レンズと、物体側に
凸面を向けたメニスカス状の正レンズで構成されてお
り、数値実施例1の2枚の凹レンズを1枚で構成してい
る。これにより、レンズ枚数が削減されコストダウンに
つながる、前玉が軽量化されるといったメリットがあ
る。以下レンズデータを示す。The present embodiment is different from Numerical Embodiment 1 in that the number of components of the first lens unit is two. In this embodiment, a negative meniscus lens having a concave surface facing the image side and a positive meniscus lens having a convex surface facing the object side are used. are doing. As a result, there are advantages that the number of lenses is reduced, leading to cost reduction, and that the front lens is reduced in weight. The lens data is shown below.
【0081】[0081]
【外3】 [Outside 3]
【0082】[数値実施例4]本実施例の断面図を図1
3に、広角端,中間位置,望遠端での収差図を図14,
15,16に示す。[Numerical Embodiment 4] FIG. 1 is a sectional view of this embodiment.
FIG. 3 shows aberration diagrams at the wide-angle end, the intermediate position, and the telephoto end in FIG.
15 and 16.
【0083】本実施例は物体側から順に正の屈折力の第
1群、負の屈折力の第2群、正の屈折力の第3群で構成
され、広角端から望遠端へのズーミングに際し、第1群
は像側に凸状の往復運動、第2群は物体側へ移動、第3
群は像側へ移動する。This embodiment comprises, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power. When zooming from the wide-angle end to the telephoto end, zooming is performed. The first group moves reciprocally to the image side, the second group moves to the object side, and the third group moves to the object side.
The group moves to the image side.
【0084】本実施例が数値実施例1と異なるのは、第
2群の構成枚数4群5枚とした点である。本実施例の第
2群は物体側より順に、物体側に凸面を向けたメニスカ
ス状の正レンズ、両レンズ面が凸面の凸レンズ、両レン
ズ面が凹面の凹レンズ、凹レンズと凸レンズで構成され
全体として正の接合レンズで構成されており、数値実施
例1の物体側の正レンズ1枚を2枚で構成している。こ
れにより、第1群を発散状態で発した軸上光束を収斂さ
せる作用をレンズ2枚で分担させることができるため、
球面収差の発生を低減でき、より大口径な撮影レンズを
構成できるというメリットがある。以下レンズデータを
示す。The present embodiment differs from Numerical Embodiment 1 in that the second group has four members and four groups. The second lens unit of the present embodiment includes, in order from the object side, a meniscus positive lens having a convex surface facing the object side, a convex lens having both lens surfaces convex, a concave lens having both lens surfaces concave, and a concave lens and a convex lens as a whole. It is composed of a positive cemented lens, and one positive lens on the object side in Numerical Example 1 is composed of two lenses. Thereby, the function of converging the on-axis luminous flux emitted from the first group in the divergent state can be shared by the two lenses,
There is an advantage that generation of spherical aberration can be reduced and a larger-diameter photographing lens can be configured. The lens data is shown below.
【0085】[0085]
【外4】 [Outside 4]
【0086】[数値実施例5]本実施例の断面図を図1
7に、広角端,中間位置,望遠端での収差図を図18,
19,20に示す。[Numerical Embodiment 5] FIG. 1 is a sectional view of the present embodiment.
FIG. 7 shows aberration diagrams at the wide-angle end, at the intermediate position, and at the telephoto end.
19 and 20.
【0087】本実施例は物体側から順に正の屈折力の第
1群、負の屈折力の第2群、正の屈折力の第3群で構成
され、広角端から望遠端へのズーミングに際し、第1群
は像側に凸状の往復運動、第2群は物体側へ移動、第3
群は固定である。This embodiment comprises, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power. When zooming from the wide-angle end to the telephoto end, zooming is performed. The first group moves reciprocally to the image side, the second group moves to the object side, and the third group moves to the object side.
Groups are fixed.
【0088】本実施例が数値実施例1と異なるのは、第
3群の構成枚数を1群2枚とした点である。本実施例の
第3群は凹レンズと凸レンズで構成され全体として正の
接合レンズで構成されており、数値実施例1の単レンズ
1枚を接合で構成している。これにより、第3群にて特
に倍率色収差の補正が可能となる。倍率色収差は前述の
ように第1群にてズーム変動が大きいが、本実施例の場
合は返変動成分を第1群で補正し、絶対量を第3群にて
補正分担することができる。これにより、ズーム比を上
げた場合にも変倍全域に渡って倍率色収差が良好に補正
できるというメリットがある。The present embodiment is different from Numerical Embodiment 1 in that the number of components of the third lens unit is two per group. The third group of the present embodiment is composed of a concave lens and a convex lens, and is composed of a positive cemented lens as a whole, and one single lens of Numerical Embodiment 1 is composed of a cemented lens. Thereby, the chromatic aberration of magnification can be particularly corrected in the third lens unit. Although the chromatic aberration of magnification has a large zoom variation in the first lens unit as described above, in the case of the present embodiment, the return variation component can be corrected by the first lens unit, and the absolute amount can be shared by the third lens unit. This has the advantage that chromatic aberration of magnification can be favorably corrected over the entire zoom range even when the zoom ratio is increased.
【0089】また、変倍に際して第3群を固定としてい
る点が数値実施例1と異なる。第3群を固定とすること
により移動機構が必要なく、鏡筒構成が簡素化されると
いうメリットがある。以下レンズデータを示す。Also, it differs from Numerical Embodiment 1 in that the third lens unit is fixed during zooming. By fixing the third group, there is an advantage that a moving mechanism is not required and the lens barrel configuration is simplified. The lens data is shown below.
【0090】[0090]
【外5】 [Outside 5]
【0091】以下、本発明の実施例における各条件式の
値を示す。The values of the conditional expressions in the embodiment of the present invention are shown below.
【0092】[0092]
【表1】 [Table 1]
【0093】[0093]
【発明の効果】本発明によれば、固体撮像素子を用いた
撮影系に好適な、構成レンズ枚数の少ない、コンパクト
で、小径化を達成した高変倍比で、特に色収差が良好に
補正され、優れた光学性能を有するズームレンズを達成
することができる。According to the present invention, a compact zoom lens having a small number of constituent lenses, a high zoom ratio achieving a small diameter, and particularly excellent chromatic aberration, which is suitable for a photographing system using a solid-state image sensor, can be obtained. Thus, a zoom lens having excellent optical performance can be achieved.
【図1】本発明の数値実施例1のレンズ断面図FIG. 1 is a sectional view of a lens according to a numerical example 1 of the present invention.
【図2】本発明の数値実施例1の広角端の収差図FIG. 2 is an aberration diagram at a wide-angle end according to Numerical Embodiment 1 of the present invention.
【図3】本発明の数値実施例1の中間の収差図FIG. 3 is an intermediate aberration diagram of the numerical example 1 of the present invention.
【図4】本発明の数値実施例1の望遠端の収差図FIG. 4 is an aberration diagram at a telephoto end in Numerical Example 1 of the present invention;
【図5】本発明の数値実施例2のレンズ断面図FIG. 5 is a sectional view of a lens according to a second numerical embodiment of the present invention;
【図6】本発明の数値実施例2の広角端の収差図FIG. 6 is an aberration diagram at a wide angle end according to Numerical Example 2 of the present invention.
【図7】本発明の数値実施例2の中間の収差図FIG. 7 is an intermediate aberration diagram of the numerical example 2 of the present invention.
【図8】本発明の数値実施例2の望遠端の収差図FIG. 8 is an aberration diagram at a telephoto end in Numerical Example 2 of the present invention.
【図9】本発明の数値実施例3のレンズ断面図FIG. 9 is a sectional view of a lens according to a numerical example 3 of the present invention.
【図10】本発明の数値実施例3の広角端の収差図FIG. 10 is an aberration diagram at a wide angle end according to Numerical Example 3 of the present invention.
【図11】本発明の数値実施例3の中間の収差図FIG. 11 is an intermediate aberration diagram of the numerical example 3 of the present invention.
【図12】本発明の数値実施例3の望遠端の収差図FIG. 12 is an aberration diagram at a telephoto end in Numerical Example 3 of the present invention.
【図13】本発明の数値実施例4のレンズ断面図FIG. 13 is a sectional view of a lens according to a numerical example 4 of the present invention.
【図14】本発明の数値実施例4の広角端の収差図FIG. 14 is an aberration diagram at a wide angle end according to Numerical Example 4 of the present invention.
【図15】本発明の数値実施例4の中間の収差図FIG. 15 is an intermediate aberration diagram of the numerical example 4 of the present invention.
【図16】本発明の数値実施例4の望遠端の収差図FIG. 16 is an aberration diagram at a telephoto end in Numerical Example 4 of the present invention.
【図17】本発明の数値実施例5のレンズ断面図FIG. 17 is a sectional view of a lens according to a numerical example 5 of the present invention.
【図18】本発明の数値実施例5の広角端の収差図FIG. 18 is an aberration diagram at a wide angle end according to Numerical Example 5 of the present invention.
【図19】本発明の数値実施例5の中間の収差図FIG. 19 is an intermediate aberration diagram of the numerical example 5 of the present invention.
【図20】本発明の数値実施例5の望遠端の収差図FIG. 20 is an aberration diagram at a telephoto end in Numerical Example 5 of the present invention;
【符号の説明】 L1 第1群 L2 第2群 L3 第3群 SP 絞り IP 像面 d d線 g g線 S サジタル像面 M メリディオナル像面[Description of Signs] L1 First lens unit L2 Second lens unit L3 Third lens unit SP Aperture IP Image plane d d-line g g-line S Sagittal image plane M Meridional image plane
フロントページの続き Fターム(参考) 2H087 KA02 KA03 MA12 MA14 NA02 PA06 PA07 PA08 PA18 PA19 PB07 PB08 PB09 QA02 QA07 QA17 QA21 QA22 QA25 QA34 QA37 QA41 QA45 QA46 RA05 RA12 RA36 RA41 RA43 SA14 SA16 SA19 SA62 SA63 SA64 SB03 SB04 SB15 SB16 SB22 SB23 Continued on the front page F-term (reference) 2H087 KA02 KA03 MA12 MA14 NA02 PA06 PA07 PA08 PA18 PA19 PB07 PB08 PB09 QA02 QA07 QA17 QA21 QA22 QA25 QA34 QA37 QA41 QA45 QA46 RA05 RA12 RA36 RA41 RA43 SA14 SB16 SA32 SB03 SB SB23
Claims (11)
の屈折力の第2群、そして正の屈折力の第3群を有し、
広角端から望遠端への変倍時に第1群と第2群との間隔
が縮まり、第2群と第3群との間隔が広がるズームレン
ズにおいて、該第1群は像面側に凹面を向けたメニスカ
ス状の負レンズ、物体側に凸面を向けたメニスカス状の
正レンズを有し、該第2群は最も像面側に負レンズと正
レンズより構成され全体として正の屈折力の接合レンズ
Aと、該接合レンズAより物体側のレンズ中最も像面側
のレンズBは像面側のレンズ面が像面側に凹面を向けた
形状であることを特徴とするズームレンズ。A first lens unit having a negative refractive power, a second lens unit having a positive refractive power, and a third lens unit having a positive refractive power.
In a zoom lens in which the distance between the first group and the second group is reduced at the time of zooming from the wide-angle end to the telephoto end and the distance between the second group and the third group is widened, the first group has a concave surface on the image surface side. A negative meniscus lens directed toward the lens, and a positive meniscus lens directed convex toward the object side. The second group is composed of a negative lens and a positive lens closest to the image plane, and has a positive refractive power as a whole. A zoom lens, characterized in that a lens A and a lens B closest to the image plane among lenses closer to the object side than the cemented lens A have a shape in which a lens surface on the image plane side is concave toward the image plane.
をfc、前記第2群の焦点距離をf2、前記接合レンズ
Aの物体側のレンズ面の曲率半径をRa、前記レンズB
の像面側のレンズ面の曲率半径をRbとしたとき、 0.5<fc/f2<2.0 0.5<(Ra+Rb)/(Ra−Rb)<2.5 の条件式を満足することを特徴とする請求項1記載のズ
ームレンズ。2. The focal length of the cemented lens A in the second group is fc, the focal length of the second group is f2, the radius of curvature of the object-side lens surface of the cemented lens A is Ra, and the lens B is
When the radius of curvature of the lens surface on the image surface side of Rb is Rb, the following conditional expression is satisfied: 0.5 <fc / f2 <2.0 0.5 <(Ra + Rb) / (Ra−Rb) <2.5 The zoom lens according to claim 1, wherein:
面を向けた正レンズ、像面側に凹面を向けた負レンズ、
そして接合レンズを有することを特徴とする請求項2記
載のズームレンズ。3. The second group is a positive lens having a convex surface facing the object side in order from the object side, a negative lens having a concave surface facing the image surface side,
The zoom lens according to claim 2, further comprising a cemented lens.
の屈折力の第2群、そして正の屈折力の第3群を有し、
広角端から望遠端への変倍時に第1群と第2群との間隔
は縮まり、第2群と第3群との間隔は広がるズームレン
ズにおいて、該第1群は像面側に凹面を向けたメニスカ
ス状の負レンズ、物体側に凸面を向けたメニスカス状の
正レンズを有し、該第2群は両レンズ面が凹面の負レン
ズと、該負レンズより物体側に配置され、物体側に凸面
を向けた正レンズ、さらに該負レンズより像面側に配置
され負レンズと正レンズより構成され、全体として正の
屈折力の接合レンズを有することを特徴とするズームレ
ンズ。4. It has a first group of negative refractive power, a second group of positive refractive power, and a third group of positive refractive power in order from the object side,
At the time of zooming from the wide-angle end to the telephoto end, the distance between the first and second groups is reduced and the distance between the second and third groups is increased. In the zoom lens, the first group has a concave surface on the image surface side. A negative meniscus lens directed toward the object, a meniscus positive lens having a convex surface facing the object side, and the second group is disposed on the object side with respect to the negative lens having both concave lens surfaces and the negative lens. A zoom lens, comprising: a positive lens having a convex surface facing the other side; and a cemented lens having a positive refractive power as a whole, comprising a negative lens and a positive lens disposed on the image side of the negative lens.
n、前記第2群の焦点距離をf2、前記第2群中の最も
物体側に配置され物体側に凸面を向けた正レンズの物体
側のレンズ面の曲率半径をRc、像面側のレンズ面の曲
率半径をRdとしたとき、 0.3<|fn|/f2<2.0 0<(Rd+Rc)/(Rd−Rc)<2.5 の条件式を満足することを特徴とする請求項4記載のズ
ームレンズ。5. The focal length of the negative lens in the second group is f
n, the focal length of the second group f2, the radius of curvature of the object-side lens surface of the positive lens of the second group closest to the object side with the convex surface facing the object side Rc, and the lens on the image plane side When the radius of curvature of the surface is Rd, the following conditional expression is satisfied: 0.3 <| fn | / f2 <2.00 <(Rd + Rc) / (Rd−Rc) <2.5. Item 8. The zoom lens according to Item 4.
レンズと負レンズで構成され全体として正の接合レンズ
で構成されることを特徴とする請求項3又は5記載のズ
ームレンズ。6. The zoom lens according to claim 3, wherein the third group includes one positive lens or a positive lens and a negative lens, and includes a positive cemented lens as a whole.
も1つのレンズ面は非球面であり、該非球面は光軸から
周辺に向かってしだいに発散作用が弱まる形状であるこ
とを特徴とする請求項3又は5記載のズームレンズ。7. The at least one lens surface of the negative lenses in the first group is an aspheric surface, and the aspheric surface has a shape whose divergence gradually decreases from the optical axis toward the periphery. The zoom lens according to claim 3 or 5, wherein
1つのレンズ面は非球面であり、該非球面は光軸から周
辺に向かってしだいに収斂作用が弱まる形状であること
を特徴とする請求項3又は5記載のズームレンズ。8. The at least one lens surface of the positive lens in the second group is an aspherical surface, and the aspherical surface has a shape whose convergence gradually decreases from the optical axis toward the periphery. The zoom lens according to claim 3.
ズの少なくとも1つのレンズ面は非球面であり、該非球
面は光軸から周辺に向かってしだいに収斂作用が弱まる
形状であることを特徴とする請求項3又は5記載のズー
ムレンズ。9. The third group has a positive lens, and at least one lens surface of the positive lens is an aspheric surface, and the aspheric surface has a shape in which a convergence effect gradually decreases from the optical axis toward the periphery. 6. The zoom lens according to claim 3, wherein:
とを特徴とする請求項3または5記載のズームレンズ。10. The zoom lens according to claim 3, wherein the third unit moves during zooming.
正の屈折力の第2群、そして正の屈折力の第3群を有
し、広角端から望遠端への変倍時に第1群と第2群との
間隔は縮まり、第2群と第3群との間隔は広がるズーム
レンズにおいて、第1群は像面側に凹面を向けたメニス
カス状の負レンズ、物体側に凸面を向けたメニスカス状
の正レンズを有し、該第2群は物体側より順に1つ又は
2つの正レンズと、両レンズ面が凹面の負レンズB、そ
して負レンズと正レンズとの接合レンズAとを有し、前
記第2群中の接合レンズAの焦点距離をfc、前記第2
群の焦点距離をf2、前記接合レンズAの物体側のレン
ズ面の曲率半径をRa、前記レンズBの像側面の曲率半
径をRb、前記第2群中のレンズBの焦点距離をfn、
前記第2群中の最も物体側に配置され物体側に凸面を向
けた正レンズの物体側面の曲率半径をRc、像面側のレ
ンズ面の曲率半径をRdとしたとき、 0.5<fc/f2<2.0 0.5<(Ra+Rb)/(Ra−Rb)<2.5 0.3<|fn|/f2<2.0 0<(Rd+Rc)/(Rd−Rc)<2.5 の条件式を満足するよう構成されたことを特徴とするズ
ームレンズ。11. A first group of negative refractive power in order from the object side,
The zoom lens has a second lens unit having a positive refractive power and a third lens unit having a positive refractive power. During zooming from the wide-angle end to the telephoto end, the distance between the first unit and the second unit is reduced, and the second unit and the second unit are changed. In a zoom lens in which the distance between the third lens unit and the third lens unit increases, the first lens unit includes a negative meniscus lens having a concave surface facing the image surface, and a positive meniscus lens having a convex surface facing the object side. In order from the object side, one or two positive lenses, a negative lens B having both concave lens surfaces, and a cemented lens A of the negative lens and the positive lens, and a focal point of the cemented lens A in the second group Distance fc, the second
The focal length of the group is f2, the radius of curvature of the object-side lens surface of the cemented lens A is Ra, the radius of curvature of the image side surface of the lens B is Rb, and the focal length of the lens B in the second group is fn.
When the radius of curvature of the object side surface of the positive lens having the convex surface facing the object side and located closest to the object side in the second group is Rc, and the radius of curvature of the lens surface on the image side is Rd, 0.5 <fc /F2<2.0 0.5 <(Ra + Rb) / (Ra-Rb) <2.5 0.3 <| fn | / f2 <2.00 <(Rd + Rc) / (Rd-Rc) <2. A zoom lens configured to satisfy the conditional expression (5).
Priority Applications (14)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP24527399A JP3652179B2 (en) | 1999-08-31 | 1999-08-31 | Zoom lens |
US09/650,861 US6545819B1 (en) | 1999-08-31 | 2000-08-29 | Zoom lens and optical apparatus having the same |
EP00307448A EP1096287B1 (en) | 1999-08-31 | 2000-08-30 | Zoom lens of the retrofocus type having three lens groups |
KR10-2000-0050973A KR100439937B1 (en) | 1999-08-31 | 2000-08-31 | Zoon lens and optical apparatus having the same |
US10/195,364 US6822808B2 (en) | 1999-08-31 | 2002-07-16 | Zoom lens and optical apparatus having the same |
KR1020020069574A KR100796106B1 (en) | 1999-08-31 | 2002-11-11 | Zoom lens and optical apparatus having the same |
KR10-2002-0069575A KR100508873B1 (en) | 1999-08-31 | 2002-11-11 | Zoom lens and optical apparatus having the same |
US10/355,176 US6862143B2 (en) | 1999-08-31 | 2003-01-31 | Zoom lens and optical apparatus having the same |
US10/934,392 US7113347B2 (en) | 1999-08-31 | 2004-09-07 | Zoom lens and optical apparatus having the same |
US10/935,225 US6999242B2 (en) | 1999-08-31 | 2004-09-08 | Zoom lens and optical apparatus having the same |
US10/935,112 US7023625B2 (en) | 1999-08-31 | 2004-09-08 | Zoom lens and optical apparatus having the same |
US11/237,806 US7113348B2 (en) | 1999-08-31 | 2005-09-29 | Zoom lens and optical apparatus having the same |
US11/427,548 US7450318B2 (en) | 1999-08-31 | 2006-06-29 | Zoom lens and optical apparatus having the same |
US11/427,546 US7227701B2 (en) | 1999-08-31 | 2006-06-29 | Zoom lens and optical apparatus having the same |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP24527399A JP3652179B2 (en) | 1999-08-31 | 1999-08-31 | Zoom lens |
Publications (2)
Publication Number | Publication Date |
---|---|
JP2001066503A true JP2001066503A (en) | 2001-03-16 |
JP3652179B2 JP3652179B2 (en) | 2005-05-25 |
Family
ID=17131236
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP24527399A Expired - Fee Related JP3652179B2 (en) | 1999-08-31 | 1999-08-31 | Zoom lens |
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JP (1) | JP3652179B2 (en) |
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US8018663B2 (en) | 2008-08-02 | 2011-09-13 | Ricoh Company, Ltd. | Image forming lens, camera and portable information terminal |
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