JPH035714A

JPH035714A - Wide converter lens

Info

Publication number: JPH035714A
Application number: JP14000589A
Authority: JP
Inventors: Noriyoshi Suzuki; 宣義鈴木; Hitoshi Mukoya; 向谷　仁志
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 1989-06-01
Filing date: 1989-06-01
Publication date: 1991-01-11

Abstract

PURPOSE:To reduce the overall size and the weight of a lens system by composing an afocal system of the 1st group which has negative refracting power and the 2nd group which has positive refracting power in order from an object side. CONSTITUTION:The wide converter lens C consists of the afocal system, which consists of the 1st group C1 with the negative refracting power and the 2nd group C with the positive refracting power. Namely, when the converter lens is mounted in front of a photographic lens to shorten the focal length of the whole photography system, the lens consists of three lens elements in specific shapes. Consequently, the afocal magnification is 0.7 times and when the lens is mounted on the photographic lens, the optical performance of the whole system is held excellent; when the lens is mounted on a zoom lens, the whole lens system is reduced in size and weight while excellent optical performance is maintained over the entire power variation range.

Description

【発明の詳細な説明】（産業上の利用分野）本発明は撮影レンズの前方に装着して撮影系全体の焦点
距離を短い方に変位させるワイドコンバーターレンズに
関し、特に写真用カメラやビデオカメラに用いられるズ
ームレンズや単一焦点距離レンズ等の撮影系に装着した
ときにｔｆ適なレンズ系全体の小型軽ＩＪ化を図り、か
つ高い光学性能を有したワイドコンバーターレンズに関
するしのである。Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a wide converter lens that is attached to the front of a photographic lens to shorten the focal length of the entire photographic system, and is particularly applicable to photographic cameras and video cameras. The present invention relates to a wide converter lens that achieves a compact and light IJ lens system that is suitable for TF when attached to a photographing system such as a zoom lens or a single focal length lens, and has high optical performance.

（従来の技術）従来より撮影レンズの前方に装着し、全系の焦点面を一
定位置に維持した状態で撮影系全体の焦点距離を短い方
に変化させるフロント方式のワイドコンバーターレンズ
が神々と提案されている。(Prior technology) A front-type wide converter lens that is attached to the front of the photographic lens and changes the focal length of the entire photographic system to a shorter one while maintaining the focal plane of the entire system at a fixed position has been proposed. has been done.

例えば特開昭５９−２０４８１７号公報では物体側より
順に負の屈折力の第１群と正の屈折力の第２群より成り
全体として５つのレンズよりアフォーカル系を構成し、
アフォーカル倍率０７倍程度のワイドコンバーターレン
ズを提案している。For example, in Japanese Patent Application Laid-Open No. 59-204817, an afocal system is composed of five lenses in total, consisting of a first group with negative refractive power and a second group with positive refractive power in order from the object side.
We are proposing a wide converter lens with an afocal magnification of approximately 0.7x.

又特開昭６３−２５３３１９号公報では３〜４枚のレン
ズより構成し、アフォーカル倍率０６倍程度のファイン
ダー系又は小型カメラ用のワイドコンバーターレンズを
提案している。Furthermore, Japanese Patent Laid-Open No. 63-253319 proposes a wide converter lens for finder systems or small cameras, which is composed of three to four lenses and has an afocal magnification of about 06 times.

一般に撮影レンズのＩＦＪ方に装着するフロント方式の
ワイドコンバーターレンズはワイドコンバーターレンズ
を装着しても全系のＦナンバーや焦点面を不変とするこ
とができるという長所を有している。In general, a front-type wide converter lens that is attached to the IFJ side of a photographic lens has the advantage that the F number and focal plane of the entire system can be kept unchanged even if the wide converter lens is attached.

（発明が解決しようとする問題点）最近のビデオカメラ・スチルカメラ簿においては、撮影
レンズの小型、軽ｔｔ化に伴い、これに装着するワイド
コンバーターレンズにも、小型軽ｔのものが要求されて
いる。ワイドコンバータレンズは多くの場合アフォーカ
ル系で構成されており、小型軽看を図るにはアフォーカ
ル倍率を大きくするか、アフォーカル系を構成する各光
学要素の屈折力を高めることが必要である。(Problems to be Solved by the Invention) In recent years, as the photographic lenses of video cameras and still cameras have become smaller and lighter, the wide converter lenses attached to them are also required to be smaller and lighter. ing. Wide converter lenses are often composed of an afocal system, and in order to make them compact and lightweight, it is necessary to increase the afocal magnification or increase the refractive power of each optical element that makes up the afocal system. .

しか・しなからアフォーカル倍率を大きくすると焦点距
離の変化暖か少なくなり、ワイドコンバタ−レンズとし
ての変位効果が少なくなる。又、各光学要素の屈折力を
高めると変化用は大きくなるが装着したときの収差の発
生が大きくなり、充分な収差補正ができず、光学性能の
劣化をまねくという問題点があった。However, if the afocal magnification is increased, the change in focal length will be less pronounced, and the displacement effect as a wide converter lens will be reduced. Furthermore, if the refractive power of each optical element is increased, the refractive power becomes larger, but the occurrence of aberrations increases when the optical element is installed, and there is a problem in that sufficient aberration correction cannot be performed, leading to deterioration of optical performance.

この他、ワイドコンバーターレンズを装着する撮影レン
ズがズームレンズの場合、撮影画角が変倍により変化す
る為全変倍範囲にわたり良好なる光字性能を得ることが
難しいという問題点があった。In addition, when the photographic lens to which the wide converter lens is attached is a zoom lens, there is a problem in that it is difficult to obtain good optical character performance over the entire magnification range because the photographing angle of view changes as the magnification changes.

本発明はレンズ構成を適切に設定することにより、連形
レンズの物体側に装着し、全系の焦点距離を短い方に変
位させることのできる全体として３枚のレンズより成る
アフォーカル倍率０．７倍程度を有し、又、装着したと
きの全系の光学性能を良好に維持することができ、しか
もレンズ系全体の小型装置化を図ったワイドコンバータ
ーレンズの堤供を目的とする。The present invention has an afocal magnification of 0.5 mm, consisting of three lenses, which can be attached to the object side of a continuous lens and shift the focal length of the entire system to the shorter side by appropriately setting the lens configuration. The object of the present invention is to provide a wide converter lens which has a magnification of about 7 times, can maintain good optical performance of the entire system when attached, and is designed to miniaturize the entire lens system.

（問題点を解決する為の手段）本発明のワイドコンバーターレンズは、撮影レンズの前
方に装着し、全系の焦点距離を短い方に変位させるワイ
ドコンバーターレンズにおいて、該ワイドコンバーター
レンズは物体側より順に負の屈折力の第１群と正の屈折
力の第２群でアフォーカル系を構成し、該第１群は像面
側に凹面を向けたメニスカス状の負の第１１レンズより
成り、該第２群は物体側に凹面を向けたメニスカス状の
負の第２１レンズ面が凸面の第２２レンズより成ってい
ることを特徴としている。(Means for solving the problem) The wide converter lens of the present invention is a wide converter lens that is attached in front of a photographic lens and shifts the focal length of the entire system to a shorter side. A first group having a negative refractive power and a second group having a positive refractive power constitute an afocal system, and the first group is composed of a meniscus-shaped negative eleventh lens with a concave surface facing the image plane side, The second lens group is characterized by having a meniscus-shaped negative 21st lens surface with a concave surface facing the object side, and a 22nd lens with a convex surface.

る。Ru.

（実施例）第１図は本発明のワイドコンバーターレンズを撮影レン
ズの前方に装着したときの一実施例のレンズ断面図であ
る。(Embodiment) FIG. 1 is a sectional view of an embodiment of the wide converter lens of the present invention when it is mounted in front of a photographic lens.

同図においてＣはワイドコンバーターレンズでありアフ
ォーカル系より成り、負の屈折力の第１群ＣＩと正の屈
折力の第２群Ｃ２より成っている６Ｍは撮影レンズであ
り同図ではズームレンズを用いた場合を示している。In the figure, C is a wide converter lens, which is an afocal system, and 6M is a photographic lens, which is a zoom lens, which is made up of a first group CI with negative refractive power and a second group C2 with positive refractive power. This shows the case where .

トはフォーカス部、Ｖｌはバリエータ−１■２はコンペ
ンセーター、Ｒはリレーレンズである。G is a focus section, Vl is a variator, 1 and 2 are compensators, and R is a relay lens.

般に撮影レンズはそれ自身で撮影を行う為に撮影レンズ
ＩｌＮ独で良好に収差補ｉＥがなされている。この為ワ
イドコンバーターレンズを装着したときに全体的に良好
なる光学性能を得るにはワイドコンバーターレンズ単独
で良好なる収差補ｉＥを達成しておく必要がある。In general, since the photographic lens performs photographing by itself, aberrations are well compensated for by the photographic lens IIN alone. Therefore, in order to obtain good overall optical performance when a wide converter lens is attached, it is necessary to achieve good aberration compensation iE with the wide converter lens alone.

木実施例においてはワイドコンバーターレンズＣをズー
ムレンズＭに装着した場合、軸外光束はズームレンズを
広角端に変倍したときに第１群で光軸１−Ｍも高く入射
する為、軸外収差の補正が重要となってくる。又軸上光
束はズームレンズを望遠端に変倍したときに第２群で光
軸り最も高く入射する為、このときは球面収差の補正か
ｍＷとなってくる。In the tree embodiment, when the wide converter lens C is attached to the zoom lens M, the off-axis light flux is incident on the optical axis 1-M at a high level in the first group when the zoom lens is zoomed to the wide-angle end. Correction of aberrations becomes important. Furthermore, since the axial light beam is incident on the second group at the highest level along the optical axis when the zoom lens is zoomed to the telephoto end, the correction for spherical aberration becomes mW at this time.

そこで本実施例では第１ｉＣ１を像面側に凹面を向けた
メニスカス状の負の第１１レンズより構成し、これによ
りズームレンズを広角端に変倍したときの軸外収差の補
正を良好に行っている。Therefore, in this embodiment, the first iC1 is composed of a meniscus-shaped negative 11th lens with a concave surface facing the image plane side, and as a result, off-axis aberrations can be well corrected when the zoom lens is zoomed to the wide-angle end. ing.

又第２群を物体側°から順に物体側に凹面を向けたメニ
スカス状の負の第２１レンズ面か凸面の第２２レンズよ
り構成し、これによりズームレンズを望遠端へ変倍した
ときの球面収差の補正を良好に補正している。In addition, the second group consists of either a meniscus-shaped negative 21st lens surface with a concave surface facing the object side or a convex 22nd lens in order from the object side, so that when the zoom lens is zoomed to the telephoto end, the spherical surface becomes Aberrations are well corrected.

本実施例では以上のようにワイドコンバータレンズＣを
構成することにより、全系の焦点距離を短い方向に変位
させると共にレンズ系全体の光学性能を良好に維持して
いる。In this embodiment, by configuring the wide converter lens C as described above, the focal length of the entire system is shifted in the short direction, and the optical performance of the entire lens system is maintained favorably.

本発明の目的とするワイドコンバーターレンズは前述の
如く構成することにより達成されるが更に撮影レンズの
前方に装着したときのレンズ系全体の光学性源を良好に
維持する為には次の諸条件を満足させるのか良い。The wide converter lens that is the object of the present invention can be achieved by configuring as described above, but in order to maintain good optical properties of the entire lens system when mounted in front of the photographic lens, the following conditions must be met. Is it good to satisfy?

ワイドコンバーターレンズを装着する前記撮影レンズの
基準の焦点距離をＦ、前記第１群と第２群の焦点距離を
各ｔｚｆ１．ｆ２、前記第１１レンズの材質のアッベ数
をν１、前記第２群の各レンズの材質のアツベ数のモ均
値をν２、前記第２ルンズの物体側のレンズ面の曲率″
Ｆ−径をＲＩＩ　。The reference focal length of the photographing lens to which the wide converter lens is attached is F, and the focal lengths of the first and second groups are each tzf1. f2, the Abbe number of the material of the eleventh lens is ν1, the average value of the Abbe number of the material of each lens of the second group is ν2, the curvature of the object-side lens surface of the second lens.
F-diameter RII.

ｌ、ワイドコンバーターレンズを該撮影レンズに装着し
たときの最大画角をωとしたときｓ、：＋く　１ｒ１１
−　・ｔａｎ　　ωぐ９．０・・・・・・・・・・・・
（＋）２１く１ＲＩＩ　　、Ｉｔ／（ｆ２／Ｆ）く１．
８・・・・・・・・・・・・（２）５５　くνｌ　・・
・・・・・・・・・・・・・・・・・・・・・・・・（
３）５３（ν２・・・・・・・・・・・・・・・・・・
・・・・・・・・（４）なる条件を満足することである
。l, When the maximum angle of view when the wide converter lens is attached to the photographic lens is ω, s: + 1r11
- ・tan ωg9.0・・・・・・・・・・・・
(+)21ku1RII, It/(f2/F)ku1.
8・・・・・・・・・・・・(2)55 kuνl...
・・・・・・・・・・・・・・・・・・・・・・・・(
3) 53(ν2・・・・・・・・・・・・・・・・・・
......(4) must be satisfied.

条件式（１）は第１群の屈折力に関し、主にワイドコン
バーターレンズの全長の短縮化及び収差補正を良好に行
うろの条件である。Conditional expression (1) relates to the refractive power of the first group, and is mainly a condition for shortening the overall length of the wide converter lens and correcting aberrations well.

ト限１１αを超えるとアフォーカル系とする為の第１群
と第２群の空気間隔が増大しレンズ全長が増大してくる
。If the limit 11α is exceeded, the air gap between the first and second groups to form an afocal system increases, and the overall length of the lens increases.

又上限額を超λると撮影レンズをズームレンズより構成
したとき、該ズームレンズを広角端とした時の軸外収差
、特に非点収差が増大しこれを補任ニするのが難しくな
ってくる。Furthermore, if the upper limit exceeds λ, when the photographic lens is composed of a zoom lens, off-axis aberrations, especially astigmatism, increase when the zoom lens is set to the wide-angle end, and it becomes difficult to compensate for this. .

条件式（２）は第２ルンズの物体側のレンズ面の曲率゛
ト径に対する第２群の屈折力に関し、にに歪曲収差及び
非点収差を良好に補ｌＥする為の条件である。−上限額
を超えると条件式（１）と同様に撮影レンズをズームレ
ンズより構成したとき、ズームレンズを広角端とした時
の非点収差が増大し、これを良好に補正するのが難しく
なってくる。Conditional expression (2) relates to the refractive power of the second group relative to the curvature and diameter of the object-side lens surface of the second lens, and is a condition for properly compensating for distortion and astigmatism. - If the upper limit is exceeded, as in conditional expression (1), when the photographic lens is composed of a zoom lens, astigmatism increases when the zoom lens is set to the wide-angle end, and it becomes difficult to correct this well. It's coming.

又下限値を超えるとズームレンズを広角端とした場合の
歪曲収差が負の方向へ１曽太し好ましくなしＸ　＋条件式（３）は第１群の材質のアツベ数に関し、丁にズ
ームレンズを広角端とした場合の軸外の色収差を良好に
補正する為のものである０条件式（３）を外れるとズー
ムレンズを広角端とした時の軸外光束は第１群で最も高
くなる為、軸外色収差が増大してくるので好まし、くな
い。Moreover, if the lower limit is exceeded, the distortion when the zoom lens is set at the wide-angle end increases by 1 degree in the negative direction, which is undesirable. If the zero conditional expression (3), which is used to satisfactorily correct off-axis chromatic aberration when the zoom lens is set at the wide-angle end, is not satisfied, the off-axis luminous flux will be highest in the first group when the zoom lens is set at the wide-angle end. Therefore, off-axis chromatic aberration increases, so this is not desirable.

条件式（４）は第２群を構成する各レンズの材質のアツ
ベ数の平均ｔｕｆｔに関し、主にズームレンズを望遠端
とした場合の軸上の色収差を良好に補正する為のもので
ある６条件式（４）を外れるとズームレンズを望遠端と
した時の軸１−光東は第２群で最も高くなる為、軸上色
収差が増大してくるので好ましくない。Conditional expression (4) relates to the average tuft of the Abbe number of the material of each lens constituting the second group, and is mainly used to satisfactorily correct axial chromatic aberration when the zoom lens is set to the telephoto end6. If Conditional Expression (4) is not satisfied, axis 1-Koto becomes the highest in the second group when the zoom lens is set to the telephoto end, which is not preferable because axial chromatic aberration increases.

次の本発明のワイドコンバーターレンズと該ワイドコン
バーターレンズを装着する撮影レンズの数値実施例を示
す、数値実施例においてＲ１は物体側より順に第１番目
のレンズ面の曲率半径、Ｄ　ｉは物体側より第１番目の
レンズ厚及び空気間隔、Ｎｉとνｌはふ々物体側より順
に第１番目のレンズのガラスの屈折率とアッベ散である
。The following numerical examples of the wide converter lens of the present invention and the photographic lens to which the wide converter lens is attached are shown. In the numerical examples, R1 is the radius of curvature of the first lens surface from the object side, and D i is the radius of curvature of the first lens surface from the object side. The thickness of the first lens, the air gap, Ni and νl are the refractive index and Abbe dispersion of the glass of the first lens in order from the object side.

又前述の各条件式と数値実施例における諸数値撮影レン
ズ：数値実施例との関係を表−１に示す。Further, Table 1 shows the relationship between each of the above-mentioned conditional expressions and various numerical photographing lenses in the numerical examples: Numerical examples.

Ｆ＝　　１　〜７６ＦＮＯ＝Ｉ：１．２〜１．８２ω：５０゜７９〜７１５Ｒ１＝　　　１４．５８　　ＤＩ＝Ｒ２＝　　　４．７６　０２＝１１３＝　　−１０，９８０３＝Ｒ４＝　　　４．０９　０４＝Ｒ５−１１，０９０５− １１６＝　　　２０．８１　０６＝Ｒ７＝　　　１．６６　０７− Ｒ８＝　　　−２，０００８＝Ｒ９＝　　　２．１４　０９− １１１０＝　　−６９，４２０ＩＯ＝Ｒ１１エ　−３．４１　　ＤＩｌ＝Ｒ１２＝　　−２９，３６０１２− Ｒ１３＝　　　１４．０２　０＋３＝Ｒ１４＝　　　−２，７７０１４− Ｒ１５＝　　（絞り）　　ＤＩ５＝ＲＩ６＝　　　３．１８　　Ｄ１６＝Ｒ１７＝　　　−６，８９ＤＩ？＝ＲＩｇ＝　　−２，８４Ｄ１８＝ＲＩ９＝　　　１９．７３　　Ｄ１９＝Ｒ２０＝　　　
２．２５　０２０＝Ｒ２１・　−１９，７７０２１＝Ｒ２２＝　　　９１．３４　０２２＝Ｒ２３＝　　　　１．３６　　Ｄ２３＝Ｒ２４−４，８
５Ｄ２４＝Ｒ２Ｓ＝　　　−２，７９Ｄ２５＝Ｒ２６＝　　　　１．５５　０２６＝Ｒ２７＝　−２５９，９４０２７＝Ｒ２１１＝　　　００　　　　ｏｚｇ−Ｒ２９＝　　　
ω ２１０．８１０．０２０、４４可変０．１１４３０．１００．２９可変０．１２可変０．５１０．１１０．２２０．５８０．１８０、Ｉ４０．０１０．５９０８０．０８０、＋５０．３００、Ｏｌ３７０．５５０．６７Ｎ　　ｌ＝１．ｌｌ０５１８Ｎ　２＝１．５０３１１Ｎ　３＝１．６９６８ＯＮ　４＝１．７７２５ＯＮ　５＝ｉ、６９６８ＯＮ　６−１．８４６６６Ｎ　７＝１．６９６８ＯＮ　１ｌ＝１．６０３１１Ｎ　９＝１．６３８５４Ｎ１０＝１．８０５１８Ｎｌｌ＝１．５５８４４ＮＩ２＝１．８３４０ＯＮＩ３＝１．５１６３３ＮＩ４＝１．６２２９９Ｎ１５＝１．５！６３３ ν　１＝２５．４ ν　２＝６０．７３＝５５．５ ν　４＝　　４９．６シ　５＝５５．５ ν　６＝２３．９ ν　７＝５５．５ ν　ｇ＝　６０．７シ　９＝５５．４ｖｌｏ；　２５．４ ν１１＝　５０．９ ν１２＝　３７．２ ν１３＝　６４．１ ν１４＝　６８．１ ν１５＝　６４．１撮影レンズ：数値実施例Ｆ＝　　１　〜９．１４ＦＮＯ＝Ｉ：１．４〜１．７２ω＝５２．６３〜６．１９ワイドコンバーターレンズ：数値実施例１（数値実施例
１の撮影レンズに装着）１− Ｒ２＝Ｒ３＝Ｒ４＋！Ｒ５＝６− ８０．３３５４、７３０ −４．７１６ −７、５０７１４．７１７４７７Ｄ　Ｉ−０，３２４Ｎ　ｌ＝１．５８９１３Ｄ　２−２
．４４８Ｄ　３＝　０．２４６　　Ｎ　Ｚ＝１．５＋６３３０４
＝　０．０３４Ｄ　５＝　０．７８２　　Ｎ　３−１．６０３１１ν　
ｌ−６１，２ ν　２＝６４．１ ν　３＝６０．７主レンズに装着した場合の画角２ω＝６６．７°〜９．９１１２．５９　　Ｄ　　Ｉ＝５．４４０２＝２０．０９　０３＝５、ｌ５０４＝１６．５６　０５＝１５．１２　０６＝１．７６　０７＝ −２，１２０８＝２．２６　０９＝１１．０８　０ＩＯ＝３．０１　　ＤＩ＋＝ −２０，３２０１２＝１２．２９　０１３− −３．２９　０１４＝（絞り）　Ｄ１５＝４．６３　　ＤＩ６＝ −１９，６９ＤＩ？＝ −３，０００１８＝ −８，８４Ｄ１９＝２．７６　０２０冨１０９．４２　　Ｄ２１＝２．８２　　Ｄ２２＝、４１　０２３＝１０８．８６　０２４＝５．５０　０２５＝９７　０２６＝ −６３，＋６　　Ｄ２７＝ｃｏ　　　Ｄ２８；０．３１１、１２０．０１０．６０可変０．１４０．５４０．１２０．４２可変０．１２可変４７０゜０９０．２４０．３８０．２２１４０．０１０．４８．３２０．１２２２３００．０＋０．４３０．６００．７２Ｎ　　Ｉ＝１．８０５１８　　　　ν　１＝２５．４Ｎ
　２＝１．６１２７１　　　　ν　２＝５８．８Ｎ　　
３＝１．６２２９９ ν　３＝５８．１Ｎ　４＝１．８３４００４＝３７．２Ｎ　５＝１．７１２９９Ｎ　６＝１．８４６６６シ　５＝５３．８ ν　５＝２３．９Ｎ　７．ｉ、６９６８０ ν　７＝５５．５Ｎ　１ｌ＝１．７１２９９ ν　ｇ＝５３．ｌｌＮ　９＝１．６２２９９９＝５１１．１ＮｌＯ＝１．８４６６６シＩＯ＝　２３．９Ｎｌｌ＝１．６２２９９ νｌ＋＝５８．１ＮＩ２−１．８０５１８ ν１２＝　２５．４Ｎ１３＝１．５１６３３ ν１３＝　６４．１Ｎ１４＝１．６２２９９ ν１４＝　５１１．１Ｎ１５＝１．５１６３３ ν１５＝　６４．１ワイドコンバーターレンズ、数値実施例２（数値実施例
２の撮影レンズに装着）ＲＩ＝　　２０．７３６　０　ｌ＝　０．４２２　　Ｎ
　ｌ＝１．６２２９９Ｒ２＝　　　５．４６７　０２＝
３．１４７Ｒ３＝　　−４，９４４０３＝　０．３６２
　　Ｎ　２−１．５１７４２Ｒ４＝　　−８，１５２Ｄ
　４＝　０．０３６Ｒ５＝＋９゜５４６　　Ｄ　５−１
．２７９　　Ｎ　３＝１．５１６３３Ｒ６＝　　−７，
４１７主レンズに装着した場合の画角２ω＝６９．０’〜８．６゜ ν　ｌ−５８，１ ν　２＝５２．４ ν　３＝６４．１ワイドコンバーターレンズ、数値実施例３（数値実施例
２の撮影レンズに装着）ＲＩ−３１，７７２０ｌ＝　０．４２２　　Ｎ　ｌ＝１
．６２２９９Ｒ２＝　　　５．７９９　０２＝３．００
１Ｒ３＝　　−５，１５５０３−０，３６２Ｎ　２＝１
．５１７４２Ｒ４＝　　−８，３１７０４纂０．０３６
Ｒ５＝　　２１．８５８　０５−　１．２７９　　Ｎ　
３−１．５６３８４Ｒ６エ　−７、９９７主レンズに装着した場合の画角２ω＝６９．０°〜８．６６１−５８．１ ν　２＝５２．４ ν　３＝６０．７（発明の効果）本発明によれば撮影レンズの前方に装着して撮影系全体
の焦点距離を短い方へ変位させる際、前述の条件を満足
する所定形状の３つのレンズよりレンズ。F= 1 ~ 76 FNO = I: 1.2 ~ 1.8 2ω: 50° 79 ~ 715 R1 = 14.58 DI = R2 = 4.76 02 = 113 = -10,9803 = R4 = 4.09 04 = R5-11,0905- 116= 20.81 06= R7= 1.66 07- R8= -2,0008= R9= 2.14 09- 1110= -69,420IO= R11e -3.41 DIl= R12= -29,36012- R13= 14.02 0+3= R14= -2,77014- R15= (Aperture) DI5= RI6= 3.18 D16= R17= -6,89 DI? = RIg= -2,84D18= RI9= 19.73 D19=R20=
2.25 020= R21・-19,77021= R22= 91.34 022= R23= 1.36 D23=R24-4,8
5D24= R2S= -2,79D25= R26= 1.55 026= R27= -259,94027= R211= 00 ozg-R29=
ω 21 0.81 0.02 0, 44 Variable 0.11 43 0.10 0.29 Variable 0.12 Variable 0.51 0.11 0.22 0.58 0.18 0, I4 0.01 0. 59 08 0.08 0, +5 0.30 0, Ol 37 0.55 0.67 N l=1. ll0518 N 2 = 1.50311 N 3 = 1.6968O N 4 = 1.7725O N 5 = i, 6968O N 6-1.84666 N 7 = 1.6968O N 1l = 1.60311 N 9 = 1.63854 N10 =1.80518 Nll=1.55844 NI2=1.8340O NI3=1.51633 NI4=1.62299 N15=1.5!633 ν 1=25.4 ν 2=60.7 3=55.5 ν 4 = 49.6 5=55.5 ν 6=23.9 ν 7=55.5 ν g= 60.7 9=55.4 vlo; 25.4 ν11= 50.9 ν12= 37.2 ν13 = 64.1 ν14= 68.1 ν15= 64.1 Photographing lens: Numerical example F= 1 ~ 9.14 FNO = I: 1.4 ~ 1.7 2ω = 52.63 ~ 6.19 Wide converter lens : Numerical Example 1 (attached to the photographing lens of Numerical Example 1) 1- R2= R3= R4+! R5= 6- 80.335 4, 730 -4.716 -7, 507 14.717 477 DI-0,324N l=1.58913D 2-2
．． 448 D 3 = 0.246 N Z = 1.5 + 63304
= 0.034 D 5 = 0.782 N 3-1.60311ν
l-61,2 ν 2 = 64.1 ν 3 = 60.7 Angle of view 2ω when attached to the main lens = 66.7° ~ 9.91 12.59 DI = 5.4402 = 20.09 03 = 5, l504 = 16.56 05 = 15.12 06 = 1.76 07 = -2,1208 = 2.26 09 = 11.08 0IO = 3.01 DI+ = -20,32012 = 12.29 013- -3.29 014= (Aperture) D15= 4.63 DI6= -19,69DI? = -3,00018= -8,84D19= 2.76 020 109.42 D21= 2.82 D22= , 41 023= 108.86 024= 5.50 025= 97 026= -63,+6 D27= co D28; 0.31 1, 12 0.01 0.60 Variable 0.14 0.54 0.12 0.42 Variable 0.12 Variable 47 0°09 0.24 0.38 0.22 14 0.01 0 .48. 32 0.12 22 30 0.0+ 0.43 0.60 0.72 N I=1.80518 ν 1=25.4N
2=1.61271 ν 2=58.8N
3=1.62299 ν 3=58.1 N 4=1.83400 4=37.2 N 5=1.71299 N 6=1.84666 5=53.8 ν 5=23.9 N 7. i, 69680 ν 7=55.5 N 1l=1.71299 ν g=53. ll N 9=1.62299 9=511.1 NlO=1.84666 IO= 23.9 Nll=1.62299 νl+=58.1 NI2−1.80518 ν12= 25.4 N13=1.51633 ν13= 64.1 N14=1.62299 ν14= 511.1 N15=1.51633 ν15= 64.1 Wide converter lens, Numerical Example 2 (attached to the photographing lens of Numerical Example 2) RI= 20.736 0 l= 0.422N
l=1.62299R2= 5.467 02=
3.147R3=-4,94403=0.362
N2-1.51742R4=-8,152D
4=0.036R5=+9゜546 D 5-1
．． 279 N3=1.51633R6=-7,
417 Angle of view 2ω when attached to the main lens = 69.0' to 8.6° ν l-58,1 ν 2 = 52.4 ν 3 = 64.1 Wide converter lens, numerical example 3 (numerical implementation Attached to the photographic lens of Example 2) RI-31,7720l= 0.422 N l=1
．． 62299R2=5.799 02=3.00
1R3=-5,15503-0,362N 2=1
．． 51742R4= -8,31704 line 0.036
R5= 21.858 05- 1.279 N
3-1.56384R6E -7,997 Angle of view 2ω when attached to the main lens = 69.0° to 8.66 1-58.1 ν 2 = 52.4 ν 3 = 60.7 (Effect of the invention ) According to the present invention, when the lens is mounted in front of the photographic lens to shift the focal length of the entire photographing system to a shorter direction, the lens is selected from three lenses having a predetermined shape that satisfies the above-mentioned conditions.

Ｍは撮影レンズである。M is a photographic lens.

Claims

[Claims] (1) In a wide converter lens that is attached to the front of the photographic lens and shifts the focal length of the entire system to the shorter side,
The wide converter lens has an afocal system consisting of a first group with negative refractive power and a second group with positive refractive power in order from the object side, and the first group has a meniscus shape with a concave surface facing the image plane. A wide converter lens comprising a negative 11th lens, the second group comprising a meniscus-shaped negative 21st lens with a concave surface facing the object side, and a 22nd lens with both lens surfaces convex. . (2) The reference focal length of the photographic lens is F, and the first
The focal lengths of the groups and the second group are respectively f1 and f2, the Abbe number of the material of the 11th lens is ν1, the average value of the Abbe numbers of the material of each lens of the second group is @ν2@, the 21st lens When the radius of curvature of the lens surface on the object side is RII, 1, and the maximum angle of view when the wide converter lens is attached to the photographic lens is ω, 5.3<|f1|/F・tanω<9.0 2 .3<|RII,1|/(f2/F)<3.855<ν
2. The wide converter lens according to claim 1, wherein the wide converter lens satisfies the following condition: 153<@ν2@.