JP2019184748A - Optical system and image capturing device - Google Patents
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Abstract
Description
本発明は、光学系及び撮像装置に関する。 The present invention relates to an optical system and an imaging apparatus.
標準画角の撮影光学系として、開口絞り物体側および像側のそれぞれに３枚のレンズを配置した所謂ガウスタイプの光学系が知られている。 As a photographing optical system having a standard angle of view, a so-called Gauss type optical system is known in which three lenses are arranged on each of the aperture stop object side and the image side.
特許文献１に記載の光学系は、当該ガウスタイプの光学系に対し、最も像面側から２番目に負レンズを追加した構成を有する。
The optical system described in
特許文献１に記載の光学系をさらに小型化しつつ、諸収差を良好に補正するためには、開口絞りの物体側と像側のレンズの構成を適切にする必要がある。
In order to satisfactorily correct various aberrations while further downsizing the optical system described in
本発明は上記課題に鑑みてなされたものであり、小型で高い光学性能を有する光学系及び撮像装置を提供することを目的とする。 The present invention has been made in view of the above problems, and an object thereof is to provide an optical system and an imaging apparatus that are small and have high optical performance.
複数のレンズ群と開口絞りを有する光学系であって、前記複数のレンズ群は、前記開口絞りの物体側に配置された正の屈折力の第１レンズ群と、前記開口絞りの像側に配置された正の屈折力の第２レンズ群からなり、前記第１レンズ群は、物体側から像側へ順に配置された、第１正レンズ、第２正レンズ、第１負レンズからなり、前記第２レンズ群は、物体側から像側へ順に配置された、少なくとも１枚のレンズ、第２負レンズ、第３正レンズからなり、前記第１レンズ群の焦点距離をｆ１、前記第２レンズ群の焦点距離をｆ２、とするとき、
０．５０＜ｆ１／ｆ２＜１．６５
なる条件式を満たすことを特徴とする。
An optical system having a plurality of lens groups and an aperture stop, wherein the plurality of lens groups are arranged on the object side of the aperture stop, the first lens group having a positive refractive power, and the image side of the aperture stop. The first lens group includes a first positive lens, a second positive lens, and a first negative lens, which are disposed in order from the object side to the image side. The second lens group includes at least one lens, a second negative lens, and a third positive lens arranged in order from the object side to the image side, and the focal length of the first lens group is f1, the second lens group, and the second lens group. When the focal length of the lens group is f2,
0.50 <f1 / f2 <1.65
The following conditional expression is satisfied.
本発明によれば、小型で高い光学性能を有する光学系及び撮像装置を提供することを目的とする。 An object of the present invention is to provide an optical system and an imaging apparatus that are small and have high optical performance.
以下、本発明の実施例に係る光学系及び撮像装置について、添付の図面に基づいて詳細に説明する。 Hereinafter, an optical system and an imaging apparatus according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.
［光学系の実施例］
各実施例の光学系は、デジタルビデオカメラ、デジタルカメラ、銀塩フィルムカメラ、テレビカメラ等の撮像装置に用いられる撮影光学系である。図１、３、５、７、９、１１に示す光学系の断面図において、左方が物体側（前方）であり、右方が像側（後方）である。また各断面図において、ｉを物体側から像側へのレンズ群の順番とすると、Ｂｉは第ｉレンズ群を示す。また、開口絞りＳＰは、開放Ｆナンバー（Ｆｎｏ）の光束を決定（制限）する。ＧＢは光学フィルター、フェースプレート、ローパスフィルター、赤外カットフィルターなどに相当する光学ブロックである。
[Example of optical system]
The optical system of each embodiment is a photographing optical system used for an imaging apparatus such as a digital video camera, a digital camera, a silver salt film camera, and a television camera. In the cross-sectional views of the optical system shown in FIGS. 1, 3, 5, 7, 9, and 11, the left side is the object side (front), and the right side is the image side (rear). In each cross-sectional view, Bi represents the i-th lens group, where i is the order of the lens group from the object side to the image side. Further, the aperture stop SP determines (limits) the light flux of the open F number (Fno). GB is an optical block corresponding to an optical filter, a face plate, a low-pass filter, an infrared cut filter, or the like.
デジタルビデオカメラやデジタルカメラなどに各実施例の光学系を使用する場合は、像面ＩＰは、ＣＣＤセンサまたはＣＭＯＳセンサ等の撮像素子（光電変換素子）に相当する。銀塩フィルムカメラに各実施例の光学系を使用する場合は、像面ＩＰはフィルム面に相当する。 When the optical system of each embodiment is used in a digital video camera, a digital camera, or the like, the image plane IP corresponds to an image sensor (photoelectric conversion element) such as a CCD sensor or a CMOS sensor. When the optical system of each embodiment is used for a silver salt film camera, the image plane IP corresponds to a film plane.
図２、４、６、８、１０、１２は、各実施例の光学系の収差図である。球面収差図において実線はｄ線（波長５８７．６ｎｍ）、二点鎖線はｇ線（波長４３５．８ｎｍ）である。非点収差図において破線ΔＭはメリディオナル像面、実線ΔＳはサジタル像面である。歪曲収差はｄ線について示している。倍率色収差はｇ線について示している。ωは半画角（度）、ＦｎｏはＦナンバーである。 2, 4, 6, 8, 10, and 12 are aberration diagrams of the optical system of each example. In the spherical aberration diagram, the solid line is the d-line (wavelength 587.6 nm), and the two-dot chain line is the g-line (wavelength 435.8 nm). In the astigmatism diagram, a broken line ΔM is a meridional image plane, and a solid line ΔS is a sagittal image plane. Distortion is shown for the d-line. The lateral chromatic aberration is shown for the g-line. ω is a half angle of view (degree), and Fno is an F number.
本明細書において、「バックフォーカス」は、レンズ最終面から近軸像面までの距離を空気換算長により表記したものとする。「レンズ全長」は、光学系の最前面から最終面までの光軸上の距離にバックフォーカスを加えた長さである。 In this specification, “back focus” represents the distance from the lens final surface to the paraxial image surface by an air-converted length. The “lens total length” is a length obtained by adding a back focus to a distance on the optical axis from the forefront surface to the final surface of the optical system.
各実施例の光学系は、複数のレンズ群と開口絞りを有し、当該複数のレンズ群は、開口絞りの物体側に配置された正の屈折力の第１レンズ群と、開口絞りの像側に配置された正の屈折力の第２レンズ群からなる。そして、第１レンズ群は、物体側から像側へ順に配置された、第１正レンズ、第２正レンズ、第１負レンズからなり、第２レンズ群は、物体側から像側へ順に配置された、少なくとも１枚のレンズ、第２負レンズ、第３正レンズからなる。さらに、第１レンズ群の焦点距離をｆ１、第２レンズ群の焦点距離をｆ２とするとき、以下の条件式（１）を満たす。
０．５０＜ｆ１／ｆ２＜１．６５ ・・・・（１）
The optical system of each embodiment includes a plurality of lens groups and an aperture stop. The plurality of lens groups includes a first lens group having a positive refractive power disposed on the object side of the aperture stop, and an image of the aperture stop. And a second lens unit having a positive refractive power disposed on the side. The first lens group includes a first positive lens, a second positive lens, and a first negative lens arranged in order from the object side to the image side, and the second lens group is arranged in order from the object side to the image side. And at least one lens, a second negative lens, and a third positive lens. Further, when the focal length of the first lens group is f1 and the focal length of the second lens group is f2, the following conditional expression (1) is satisfied.
0.50 <f1 / f2 <1.65 (1)
条件式（１）を満たすように第２レンズ群の焦点距離に対する第１レンズ群の焦点距離を短くし、第１レンズ群の屈折力を比較的強くすることによって、バックフォーカスを短くして、光学系の全長の短縮を図っている。 The back focus is shortened by shortening the focal length of the first lens group relative to the focal length of the second lens group so as to satisfy the conditional expression (1), and by relatively increasing the refractive power of the first lens group. The total length of the optical system is shortened.
一方、第１レンズ群の屈折力を強くすることによってバックフォーカスが短くなると、像面に対する光線の最大入射角が大きくなり、周辺光量が低下する。また、像面湾曲も生じやすくなる。これらに鑑み、第２レンズ群の像面側に、第２負レンズと第３正レンズを配置している。 On the other hand, when the back focus is shortened by increasing the refractive power of the first lens group, the maximum incident angle of the light beam with respect to the image plane is increased, and the peripheral light amount is decreased. Also, field curvature is likely to occur. In view of these, the second negative lens and the third positive lens are arranged on the image plane side of the second lens group.
像面に対して最大入射角で入射する光線は、軸外光束を構成する光線である。第２負レンズによって軸外光束と軸上光束を光軸に直交する方向（以下、径方向という）に分離させ、第３正レンズを通過する軸外光束の主光線の高さを適度に高くしている。第３正レンズで軸上光束に比べて軸外光束を強く屈折させることによって、軸外光束の入射角を小さくすることができる。また、像面湾曲も補正することができる。 The light beam incident on the image plane at the maximum incident angle is a light beam constituting an off-axis light beam. The off-axis light beam and the on-axis light beam are separated in a direction orthogonal to the optical axis (hereinafter referred to as the radial direction) by the second negative lens, and the height of the principal ray of the off-axis light beam passing through the third positive lens is appropriately increased. is doing. By making the third positive lens refract the off-axis light beam stronger than the on-axis light beam, the incident angle of the off-axis light beam can be reduced. In addition, field curvature can also be corrected.
条件式（１）の下限値を下回って、第１レンズ群の焦点距離が短くなり、第１レンズ群の屈折力が強くなると、球面収差や像面湾曲の補正が困難となるため好ましくない。条件式（１）の上限値を上回って、第１レンズ群の焦点距離が長くなり、屈折力が弱くなると、光学系の全長が長くなるため好ましくない。 If the focal length of the first lens group becomes shorter and the refractive power of the first lens group becomes stronger than the lower limit value of conditional expression (1), it will be difficult to correct spherical aberration and curvature of field, which is not preferable. If the upper limit of conditional expression (1) is exceeded and the focal length of the first lens unit becomes longer and the refractive power becomes weaker, the total length of the optical system becomes longer, which is not preferable.
以上のレンズ構成及び条件式を満たすことにより、小型で高い光学性能を有する光学系を得ることができる。 By satisfying the above lens configuration and conditional expressions, it is possible to obtain a small optical system having high optical performance.
なお、好ましくは条件式（１）の数値範囲を次のように設定するとよい。
０．７５＜ｆ１／ｆ２＜１．６０ ・・・（１ａ）
Preferably, the numerical range of conditional expression (1) is set as follows.
0.75 <f1 / f2 <1.60 (1a)
さらに好ましくは、条件式（１）の数値範囲を次のように設定するとよい。
０．９０＜ｆ１／ｆ２＜１．５０ ・・・（１ｂ）
More preferably, the numerical range of conditional expression (1) may be set as follows.
0.90 <f1 / f2 <1.50 (1b)
さらに、本発明の実施例に係る光学系は、条件式（２）〜（１０）のうち１つ以上を満たすことが好ましい。
１．５０＜｜ｆｎ２｜／ｓｋ＜１０．００ ・・・（２）
０．７０＜｜ｆｎ２｜／ｆ＜３．３０ ・・・（３）
０．７５＜Ｌｓ／ｆ＜０．９５ ・・・（４）
０．７０＜Ｔｄ／ｆ＜１．００ ・・・（５）
０．７０＜｜ｆｎ２｜／ｆｐ３＜４．００ ・・・（６）
０．８０＜ｆ１／ｆ＜１．７０ ・・・（７）
０．７５＜ｆｐ１／ｆ＜１．２０ ・・・（８）
０．２５＜｜ｆｎ１｜／ｆ＜０．６ ・・・（９）
０．５０＜ｆｐ１／ｆｐ３＜１．２５ ・・・（１０）
Furthermore, the optical system according to the example of the present invention preferably satisfies one or more of conditional expressions (2) to (10).
1.50 <| fn2 | / sk <10.00 (2)
0.70 <| fn2 | / f <3.30 (3)
0.75 <Ls / f <0.95 (4)
0.70 <Td / f <1.00 (5)
0.70 <| fn2 | / fp3 <4.00 (6)
0.80 <f1 / f <1.70 (7)
0.75 <fp1 / f <1.20 (8)
0.25 <| fn1 | / f <0.6 (9)
0.50 <fp1 / fp3 <1.25 (10)
第１負レンズの焦点距離をｆｎ１、第２負レンズの焦点距離をｆｎ２とする。第１正レンズの焦点距離をｆｐ１、第３正レンズの焦点距離をｆｐ３とする。光学系の焦点距離をｆとする。 The focal length of the first negative lens is fn1, and the focal length of the second negative lens is fn2. The focal length of the first positive lens is fp1, and the focal length of the third positive lens is fp3. Let f be the focal length of the optical system.
無限遠合焦時における光学系のバックフォーカスをｓｋとする。無限遠合焦時における、開口絞りから像面までの光軸上の距離をＬｓとする。なお、開口絞りから像面までの光軸上の距離Ｌｓは、開口絞りから第３正レンズの像側のレンズ面までの光軸上の距離（図１等においてＳｄで表している）にバックフォーカスを加えた距離である。無限遠合焦時における第１正レンズの物体側のレンズ面から第３正レンズの像側のレンズ面までの光軸上の距離をＴｄとする。 Let sk be the back focus of the optical system when focusing on infinity. Let Ls be the distance on the optical axis from the aperture stop to the image plane when focusing on infinity. The distance Ls on the optical axis from the aperture stop to the image plane is back to the distance on the optical axis from the aperture stop to the lens surface on the image side of the third positive lens (represented by Sd in FIG. 1 and the like). This is the distance with focus. Let Td be the distance on the optical axis from the object-side lens surface of the first positive lens to the image-side lens surface of the third positive lens when focusing on infinity.
条件式（２）の下限値を下回って、バックフォーカスに対して第２負レンズの焦点距離の絶対値が小さくなると、第２負レンズの強い負の屈折力により軸外光束と軸上光束が径方向に大きく分離される。第３正レンズを通過する軸外光束の主光線の高さが高くなり、軸外光束に対する屈折作用が強くなりすぎて、像面湾曲の補正が過剰になってしまうため好ましくない。また、像面に対する光線の最大入射角が小さくなりすぎて、光学系の全長が長くなるため好ましくない。条件式（２）の上限値を上回って、第２負レンズの焦点距離の絶対値が大きくなると、第２負レンズによる軸外光束と軸上光束を分離する力が弱くなる。これにより、第３正レンズを通過する軸外光束の高さが低くなり、軸外光束に対する屈折作用が弱くなり、像面に対する光線の最大入射角が大きくなって、周辺光量の低下を低減することが困難となるため好ましくない。 When the absolute value of the focal length of the second negative lens with respect to the back focus becomes smaller than the lower limit value of the conditional expression (2), the off-axis light beam and the on-axis light beam are caused by the strong negative refractive power of the second negative lens. Largely separated in the radial direction. The height of the principal ray of the off-axis light beam passing through the third positive lens becomes high, the refraction effect on the off-axis light beam becomes too strong, and the correction of field curvature becomes excessive, which is not preferable. Further, the maximum incident angle of the light beam with respect to the image plane becomes too small, and the total length of the optical system becomes long. If the absolute value of the focal length of the second negative lens increases beyond the upper limit value of conditional expression (2), the force separating the off-axis light beam and the on-axis light beam by the second negative lens becomes weak. As a result, the height of the off-axis light beam passing through the third positive lens is lowered, the refraction effect on the off-axis light beam is weakened, the maximum incident angle of the light beam with respect to the image plane is increased, and the decrease in the peripheral light amount is reduced. This is not preferable because it becomes difficult.
条件式（３）の下限値を下回って、光学系の焦点距離に対して第２レンズ群の焦点距離の絶対値が小さくなり、負の屈折力が強くなると、像面湾曲の補正が困難になるため好ましくない。条件式（３）の上限値を上回って、第２レンズ群の焦点距離の絶対値が大きくなり、負の屈折力が弱くなると、第３正レンズよりも物体側において軸外光束と軸上光束を分離する力が弱くなる。これにより、第３正レンズを通過する軸外光束の高さが低くなり、軸外光束に対する屈折作用が弱くなり、像面に対する光線の最大入射角が大きくなって、周辺光量の低下を低減することが困難となるため好ましくない。 If the absolute value of the focal length of the second lens unit becomes smaller than the lower limit value of the conditional expression (3) and the negative refractive power becomes strong with respect to the focal length of the optical system, it becomes difficult to correct field curvature. Therefore, it is not preferable. When the absolute value of the focal length of the second lens unit becomes larger and the negative refractive power becomes weaker than the upper limit of conditional expression (3), the off-axis light beam and the on-axis light beam are closer to the object side than the third positive lens. The power to separate is weakened. As a result, the height of the off-axis light beam passing through the third positive lens is lowered, the refraction effect on the off-axis light beam is weakened, the maximum incident angle of the light beam with respect to the image plane is increased, and the decrease in the peripheral light amount is reduced. This is not preferable because it becomes difficult.
条件式（４）の下限値を下回って、開口絞りから像面までの距離が短くなると、像面に対する光線の最大入射角が大きくなって、周辺光量の低下を低減することが困難となるため好ましくない。条件式（４）の上限値を上回って、開口絞りから像面までの距離が長くなると、光学系の全長が長くなるため好ましくない。 If the distance from the aperture stop to the image plane becomes shorter than the lower limit value of conditional expression (4), the maximum incident angle of the light beam with respect to the image plane increases, making it difficult to reduce the decrease in the amount of peripheral light. It is not preferable. If the distance from the aperture stop to the image plane becomes longer than the upper limit value of conditional expression (4), the total length of the optical system becomes longer, which is not preferable.
条件式（５）の下限値を下回って、第１正レンズの物体側のレンズ面から第３正レンズの像側のレンズ面までの距離が短くなると、光学系を構成する各レンズの屈折力が強くなり、球面収差や軸上色収差が大きくなるので好ましくない。条件式（５）の上限値を上回って、第１正レンズの物体側のレンズ面から第３正レンズの像側のレンズ面までの距離が長くなると、光学系の全長が長くなり径も大きくなって、光学系が大型化するため好ましくない。 When the distance from the object-side lens surface of the first positive lens to the image-side lens surface of the third positive lens becomes shorter than the lower limit value of conditional expression (5), the refractive power of each lens constituting the optical system Is increased, and spherical aberration and axial chromatic aberration are increased. If the distance from the object-side lens surface of the first positive lens to the image-side lens surface of the third positive lens becomes longer than the upper limit of conditional expression (5), the total length of the optical system becomes longer and the diameter increases. This is not preferable because the optical system becomes large.
条件式（６）の下限値を下回って、第２負レンズの焦点距離の絶対値が小さくなり、第２負レンズの屈折力が強くなると、軸外光束と軸上光束を分離する力が強くなる。第３正レンズによって軸上光束に比べて軸外光束を大きく屈折させる作用が強くなり、像面湾曲の補正が過剰になってしまうため好ましくない。逆に、第３正レンズの焦点距離が長くなって、第３正レンズの屈折力が弱くなると、像面に対する光線の最大入射角が大きくなって、周辺光量の低下を低減することや、像面湾曲の補正が困難となるので好ましくない。 When the absolute value of the focal length of the second negative lens becomes smaller than the lower limit value of the conditional expression (6) and the refractive power of the second negative lens becomes stronger, the force for separating the off-axis light beam and the on-axis light beam becomes stronger. Become. The third positive lens is not preferable because the action of refracting the off-axis light beam larger than the on-axis light beam becomes strong, and the correction of the field curvature becomes excessive. Conversely, when the focal length of the third positive lens is increased and the refractive power of the third positive lens is decreased, the maximum incident angle of the light beam with respect to the image surface is increased, thereby reducing the decrease in the peripheral light amount, This is not preferable because it is difficult to correct the surface curvature.
条件式（６）の上限値を上回って、第２負レンズの焦点距離の絶対値が大きくなり、第２負レンズの屈折力が弱くなると、軸外光束と軸上光束を分離する力が弱くなる。これにより、第３正レンズを通過する軸外光束の高さが低くなり、軸外光束に対する屈折作用が弱くなり、像面に対する光線の最大入射角が大きくなって、周辺光量の低下を低減することが困難となるため好ましくない。逆に、第３正レンズの焦点距離が短くなって、第３正レンズの屈折力が強くなると、像面湾曲の補正が過剰になってしまうため好ましくない。 If the absolute value of the focal length of the second negative lens becomes larger than the upper limit value of conditional expression (6) and the refractive power of the second negative lens becomes weak, the force for separating the off-axis light beam and the on-axis light beam becomes weak. Become. As a result, the height of the off-axis light beam passing through the third positive lens is lowered, the refraction effect on the off-axis light beam is weakened, the maximum incident angle of the light beam with respect to the image plane is increased, and the decrease in the peripheral light amount is reduced. This is not preferable because it becomes difficult. On the other hand, if the focal length of the third positive lens is shortened and the refractive power of the third positive lens is increased, field curvature correction becomes excessive, which is not preferable.
条件式（７）の下限値を下回って、第１レンズ群の焦点距離が短くなり、第１レンズ群の屈折力が強くなると、球面収差や軸上色収差の補正が困難になるため好ましくない。条件式（７）の上限値を上回って、第１レンズ群の焦点距離が長くなり、第１レンズ群の屈折力が弱くなると、光学系の全長が長くなるので好ましくない。 If the focal length of the first lens group becomes shorter and the refractive power of the first lens group becomes stronger than the lower limit value of the conditional expression (7), it is not preferable because correction of spherical aberration and axial chromatic aberration becomes difficult. If the upper limit of conditional expression (7) is exceeded and the focal length of the first lens group becomes longer and the refractive power of the first lens group becomes weaker, the total length of the optical system becomes longer, which is not preferable.
条件式（８）の下限値を下回って、第１正レンズの焦点距離が短くなり、第１正レンズの屈折力が強くなると、球面収差や軸上色収差の補正が困難になるため好ましくない。条件式（８）の上限値を上回って、第１正レンズの焦点距離が長くなり、第１正レンズの屈折力が弱くなると、光学系の全長が長くなるので好ましくない。 If the focal length of the first positive lens becomes shorter and the refractive power of the first positive lens becomes stronger than the lower limit value of the conditional expression (8), it is not preferable because correction of spherical aberration and axial chromatic aberration becomes difficult. If the upper limit of conditional expression (8) is exceeded and the focal length of the first positive lens becomes longer and the refractive power of the first positive lens becomes weaker, the total length of the optical system becomes longer, which is not preferable.
条件式（９）の下限値を下回って、第１負レンズの焦点距離の絶対値が小さくなり、第１負レンズの屈折力が強くなると、球面収差の補正が困難になるため好ましくない。条件式（９）の上限値を上回って、第１負レンズの焦点距離の絶対値が大きくなり、第１負レンズの屈折力が弱いと、軸上色収差の補正が困難になるため好ましくない。 If the absolute value of the focal length of the first negative lens becomes smaller than the lower limit value of conditional expression (9) and the refractive power of the first negative lens becomes stronger, it will be difficult to correct spherical aberration, which is not preferable. If the absolute value of the focal length of the first negative lens is larger than the upper limit value of conditional expression (9) and the refractive power of the first negative lens is weak, it is not preferable because it is difficult to correct axial chromatic aberration.
条件式（１０）の下限値を下回って、第１正レンズの焦点距離が短くなり、第１正レンズの屈折力が強くなると、像面湾曲の補正が過剰になるため好ましくない。条件式（１０）の上限値を上回って、第１正レンズの焦点距離が長くなり、第１正レンズの屈折力が弱くなると、光球面収差の補正が困難になるため好ましくない。 If the focal length of the first positive lens becomes shorter than the lower limit value of conditional expression (10) and the refractive power of the first positive lens becomes stronger, the correction of field curvature becomes excessive, which is not preferable. If the upper limit of conditional expression (10) is exceeded and the focal length of the first positive lens becomes longer and the refractive power of the first positive lens becomes weaker, correction of photospherical aberration becomes difficult, which is not preferable.
なお、好ましくは条件式（２）〜（１０）の数値範囲を次のように設定するとよい。
１．８０＜｜ｆｎ２｜／ｓｋ＜９．００ ・・・（２ａ）
０．７５＜｜ｆｎ２｜／ｆ＜３．２０ ・・・（３ａ）
０．８０＜Ｌｓ／ｆ＜０．９３ ・・・（４ａ）
０．７３＜Ｔｄ／ｆ＜０．９０ ・・・（５ａ）
０．７５＜｜ｆｎ２｜／ｆｐ３＜３．７０ ・・・（６ａ）
１．００＜ｆ１／ｆ＜１．６０ ・・・（７ａ）
０．８０＜ｆｐ１／ｆ＜１．１０ ・・・（８ａ）
０．３０＜｜ｆｎ１｜／ｆ＜０．５５ ・・・（９ａ）
０．６０＜ｆｐ１／ｆｐ３＜１．２０ ・・・（１０ａ）
Preferably, the numerical ranges of conditional expressions (2) to (10) are set as follows.
1.80 <| fn2 | / sk <9.00 (2a)
0.75 <| fn2 | / f <3.20 (3a)
0.80 <Ls / f <0.93 (4a)
0.73 <Td / f <0.90 (5a)
0.75 <| fn2 | / fp3 <3.70 (6a)
1.00 <f1 / f <1.60 (7a)
0.80 <fp1 / f <1.10 (8a)
0.30 <| fn1 | / f <0.55 (9a)
0.60 <fp1 / fp3 <1.20 (10a)
さらに好ましくは、条件式（２）〜（１０）の数値範囲を次のように設定するとよい。
２．００＜｜ｆｎ２｜／ｓｋ＜８．００ ・・・（２ｂ）
０．８０＜｜ｆｎ２｜／ｆ＜３．１０ ・・・（３ｂ）
０．８３＜Ｌｓ／ｆ＜０．９０ ・・・（４ｂ）
０．７６＜Ｔｄ／ｆ＜０．８８ ・・・（５ｂ）
０．８３＜｜ｆｎ２｜／ｆｐ３＜３．５０ ・・・（６ｂ）
１．２０＜ｆ１／ｆ＜１．５０ ・・・（７ｂ）
０．８３＜ｆｐ１／ｆ＜１．０５ ・・・（８ｂ）
０．３３＜｜ｆｎ１｜／ｆ＜０．５０ ・・・（９ｂ）
０．７３＜ｆｐ１／ｆｐ３＜１．１８ ・・・（１０ｂ）
More preferably, the numerical ranges of the conditional expressions (2) to (10) may be set as follows.
2.00 <| fn2 | / sk <8.00 (2b)
0.80 <| fn2 | / f <3.10 (3b)
0.83 <Ls / f <0.90 (4b)
0.76 <Td / f <0.88 (5b)
0.83 <| fn2 | / fp3 <3.50 (6b)
1.20 <f1 / f <1.50 (7b)
0.83 <fp1 / f <1.05 (8b)
0.33 <| fn1 | / f <0.50 (9b)
0.73 <fp1 / fp3 <1.18 (10b)
さらに、実施例に係る光学系は、第１負レンズの像側のレンズ面が凹面であり、開口絞りの像側に隣接して配置されたレンズの物体側のレンズ面が凹面であることが好ましい。開口絞りの両側のレンズ面を対称的な凹面とすることにより、球面収差と像面湾曲を良好に補正できる。 Further, in the optical system according to the example, the lens surface on the image side of the first negative lens is a concave surface, and the lens surface on the object side of the lens disposed adjacent to the image side of the aperture stop is a concave surface. preferable. By making the lens surfaces on both sides of the aperture stop symmetrically concave, spherical aberration and curvature of field can be corrected well.
第２レンズ群は、物体側から像側に順に配置された、２枚のレンズと、第２負レンズ、第３正レンズからなることが好ましい。特に２枚のレンズのうちの少なくとも１枚を負レンズとして、第２レンズ群に２枚以上の負レンズを配置することが好ましい。これによって、第２レンズ群内の負レンズが第２負レンズの１枚のみである場合に比べて、第１レンズ群で生じる球面収差及び軸上色収差を補正しやすくなる。また、開口絞りの物体側に隣接して配置されるレンズが負レンズであることが好ましい。開口絞りに対して第１負レンズと対称的に配置されることで、球面収差及び軸上色収差を補正しやすくなる。 The second lens group is preferably composed of two lenses, a second negative lens, and a third positive lens arranged in order from the object side to the image side. In particular, it is preferable that at least one of the two lenses is a negative lens, and two or more negative lenses are arranged in the second lens group. This makes it easier to correct spherical aberration and axial chromatic aberration that occur in the first lens group than in the case where there is only one negative lens in the second lens group. Further, it is preferable that the lens disposed adjacent to the object side of the aperture stop is a negative lens. Arranging symmetrically with the first negative lens with respect to the aperture stop makes it easier to correct spherical aberration and axial chromatic aberration.
さらに、実施例に係る光学系を構成する全てのレンズは、両面が球面形状であることが好ましい。非球面レンズを用いないことで、安価な光学系を得ることができる。 Furthermore, it is preferable that all the lenses constituting the optical system according to the example have a spherical shape on both sides. By using no aspheric lens, an inexpensive optical system can be obtained.
次に実施例１〜６の光学系について説明する。図１は実施例１の光学系ＯＰの、無限遠に合焦時の断面図であり、図２は無限遠に合焦時の光学系ＯＰの収差図である。図３は実施例２の光学系ＯＰの、無限遠に合焦時の断面図であり、図４は無限遠に合焦時の光学系ＯＰの収差図である。図５は実施例３の光学系ＯＰの、無限遠に合焦時の断面図であり、図６は無限遠に合焦時の光学系ＯＰの収差図である。図７は実施例４の光学系ＯＰの、無限遠に合焦時の断面図であり、図８は無限遠に合焦時の光学系ＯＰの収差図である。図９は実施例５の光学系ＯＰの、無限遠に合焦時の断面図であり、図１０は無限遠に合焦時の光学系ＯＰの収差図である。図１１は実施例６の光学系ＯＰの、無限遠に合焦時の断面図であり、図１２は無限遠に合焦時の光学系ＯＰの収差図である。 Next, optical systems of Examples 1 to 6 will be described. FIG. 1 is a cross-sectional view of the optical system OP of Example 1 when focused on infinity, and FIG. 2 is an aberration diagram of the optical system OP when focused on infinity. FIG. 3 is a cross-sectional view of the optical system OP of Example 2 when focused on infinity, and FIG. 4 is an aberration diagram of the optical system OP when focused on infinity. FIG. 5 is a cross-sectional view of the optical system OP of Example 3 when focused on infinity, and FIG. 6 is an aberration diagram of the optical system OP when focused on infinity. FIG. 7 is a cross-sectional view of the optical system OP of Example 4 when focused on infinity, and FIG. 8 is an aberration diagram of the optical system OP when focused on infinity. FIG. 9 is a cross-sectional view of the optical system OP of Example 5 when focused on infinity, and FIG. 10 is an aberration diagram of the optical system OP when focused on infinity. FIG. 11 is a cross-sectional view of the optical system OP of Example 6 when focusing on infinity, and FIG. 12 is an aberration diagram of the optical system OP when focusing on infinity.
実施例１〜６の光学系ＯＰは、Ｆナンバーが１．８５、半画角が約２４度、焦点距離が約４８．７の単焦点レンズ（焦点距離が一定のレンズ）である。実施例１〜５の光学系ＯＰは、物体側から像側へ順に配置された、第１レンズ群Ｂ１、開口絞りＳＰ、第２レンズ群Ｂ２を有する。第１レンズ群Ｂ１は、物体側から像側へ順に配置された、第１正レンズＬｐ１、第２正レンズＬｐ２、第１負レンズＬｎ１からなる。第２レンズ群Ｂ２は、物体側から像側へ順に配置された、レンズＬ４、レンズＬ５、第２負レンズＬｎ２、第３正レンズＬｐ３からなる。実施例１、３〜５において、レンズＬ４は負レンズであり、レンズＬ５は正レンズである。実施例２において、レンズＬ４は正レンズであり、レンズＬ５は負レンズである。実施例１〜５の光学系ＯＰのそれぞれで、各レンズの材料、レンズ同士の間隔、および光学系ＯＰのバックフォーカス等が異なる。 The optical systems OP of Examples 1 to 6 are single focus lenses (lenses with a constant focal length) having an F number of 1.85, a half angle of view of about 24 degrees, and a focal length of about 48.7. The optical systems OP of Examples 1 to 5 include a first lens group B1, an aperture stop SP, and a second lens group B2, which are arranged in order from the object side to the image side. The first lens unit B1 includes a first positive lens Lp1, a second positive lens Lp2, and a first negative lens Ln1, which are arranged in order from the object side to the image side. The second lens group B2 includes a lens L4, a lens L5, a second negative lens Ln2, and a third positive lens Lp3, which are arranged in order from the object side to the image side. In Examples 1 and 3 to 5, the lens L4 is a negative lens, and the lens L5 is a positive lens. In Example 2, the lens L4 is a positive lens, and the lens L5 is a negative lens. In each of the optical systems OP of Examples 1 to 5, the material of each lens, the distance between the lenses, the back focus of the optical system OP, and the like are different.
また、実施例６の光学系ＯＰは、物体側から像側へ順に配置された、第１レンズ群Ｂ１、開口絞りＳＰ、第２レンズ群Ｂ２を有する。第１レンズ群Ｂ１は、物体側から像側へ順に配置された、第１正レンズＬｐ１、第２正レンズＬｐ２、第１負レンズＬｎ１からなる。第２レンズ群Ｂ２は、物体側から像側へ順に配置された、レンズＬ４、第２負レンズＬｎ２、第３正レンズＬｐ３からなる。レンズＬ４は正レンズである。 In addition, the optical system OP of Example 6 includes a first lens group B1, an aperture stop SP, and a second lens group B2, which are arranged in order from the object side to the image side. The first lens unit B1 includes a first positive lens Lp1, a second positive lens Lp2, and a first negative lens Ln1, which are arranged in order from the object side to the image side. The second lens unit B2 includes a lens L4, a second negative lens Ln2, and a third positive lens Lp3, which are arranged in order from the object side to the image side. The lens L4 is a positive lens.
実施例１〜６の光学系ＯＰにおいて、第１負レンズＬｎ１の像側のレンズ面は凹面であり、レンズＬ４の物体側のレンズ面は凹面である。実施例１〜６の光学系ＯＰは、無限遠から最至近距離物体への合焦に際して、光学系ＯＰ全体が物体側に移動する。 In the optical systems OP of Examples 1 to 6, the image-side lens surface of the first negative lens Ln1 is a concave surface, and the object-side lens surface of the lens L4 is a concave surface. In the optical systems OP of Examples 1 to 6, the entire optical system OP moves to the object side when focusing from infinity to the closest object.
各実施例に係る光学系ＯＰが前述の各条件式を満たすことにより、小型で高い光学性能を有する光学系を得ることができる。 When the optical system OP according to each embodiment satisfies the above-described conditional expressions, it is possible to obtain a small and high-performance optical system.
［数値実施例］
以下に、実施例１〜６のそれぞれに対応する数値実施例１〜６を示す。また、数値実施例１〜６において、面番号は、物体側からの光学面の順序を示す。ｒは光学面の曲率半径（ｍｍ）、ｄは隣り合う光学面の間隔（ｍｍ）、ｎｄはｄ線における光学部材の材料の屈折率、νｄは光学部材の材料のアッベ数を示す。フラウンホーファー線のｇ線（波長４３５．８ｎｍ）、Ｆ線（４８６．１ｎｍ）、ｄ線（５８７．６ｎｍ）、Ｃ線（６５６．３ｎｍ）に対する材料の屈折率をそれぞれＮｇ、ＮＦ、Ｎｄ、ＮＣとするとき、アッベ数νｄを、
νｄ＝（Ｎｄ−１）／（ＮＦ−ＮＣ）
として表す。ＢＦはバックフォーカスを示す。
[Numerical example]
The numerical examples 1 to 6 corresponding to the respective examples 1 to 6 are shown below. In Numerical Examples 1 to 6, the surface number indicates the order of the optical surfaces from the object side. r is the radius of curvature (mm) of the optical surface, d is the distance between adjacent optical surfaces (mm), nd is the refractive index of the material of the optical member at d-line, and νd is the Abbe number of the material of the optical member. The refractive index of the material for the g-line (wavelength 435.8 nm), F-line (486.1 nm), d-line (587.6 nm), and C-line (656.3 nm) of the Fraunhofer line is Ng, NF, Nd, NC, respectively. If the Abbe number νd is
νd = (Nd−1) / (NF−NC)
Represent as BF indicates back focus.
数値実施例１〜６のそれぞれにおける、条件式（１）〜（１０）で用いられるパラメータの値を［表１］に示す。また、条件式（１）〜（１０）に対応する値を［表２］に示す。 The values of parameters used in the conditional expressions (1) to (10) in each of the numerical examples 1 to 6 are shown in [Table 1]. In addition, Table 2 shows values corresponding to the conditional expressions (1) to (10).
［数値実施例１］
単位 mm
面データ
面番号 r d nd vd
1 27.297 4.89 1.89190 37.1
2 75.013 0.20
3 16.729 5.94 1.71999 50.2
4 57.052 1.20 1.85478 24.8
5 11.628 5.54
6(絞り) ∞ 3.22
7 -40.625 1.00 1.72047 34.7
8 32.477 3.83 1.85150 40.8
9 -27.798 0.81
10 -19.520 1.23 1.48749 70.2
11 -107.611 7.33
12 99.876 6.74 1.69680 55.5
13 -44.707 15.14
14 ∞ 1.40 1.55900 60.0
15 ∞ 0.60
像面 ∞
焦点距離 48.70
Ｆナンバー 1.85
半画角（度） 23.95
像高 21.64
レンズ全長 58.55
BF 16.63
[Numerical Example 1]
Unit mm
Surface data surface number rd nd vd
1 27.297 4.89 1.89190 37.1
2 75.013 0.20
3 16.729 5.94 1.71999 50.2
4 57.052 1.20 1.85478 24.8
5 11.628 5.54
6 (Aperture) ∞ 3.22
7 -40.625 1.00 1.72047 34.7
8 32.477 3.83 1.85 150 40.8
9 -27.798 0.81
10 -19.520 1.23 1.48749 70.2
11 -107.611 7.33
12 99.876 6.74 1.69680 55.5
13 -44.707 15.14
14 ∞ 1.40 1.55900 60.0
15 ∞ 0.60
Image plane ∞
Focal length 48.70
F number 1.85
Half angle of view (degrees) 23.95
Statue height 21.64
Total lens length 58.55
BF 16.63
［数値実施例２］
単位 mm
面データ
面番号 r d nd vd
1 27.493 4.38 1.95375 32.3
2 75.195 0.20
3 16.091 5.99 1.65160 58.5
4 60.195 1.00 1.80518 25.4
5 11.199 4.97
6(絞り) ∞ 1.77
7 -54.721 1.99 1.88300 40.8
8 -24.700 1.00 1.89286 20.4
9 -40.223 2.62
10 -21.337 3.50 1.48749 70.2
11 -65.931 4.65
12 205.798 5.55 1.85060 41.6
13 -38.304 19.45
14 ∞ 1.40 1.55900 60.0
15 ∞ 0.59
像面 ∞
焦点距離 48.70
Ｆナンバー 1.85
半画角（度） 23.95
像高 21.64
レンズ全長 58.55
BF 20.94
[Numerical Example 2]
Unit mm
Surface data surface number rd nd vd
1 27.493 4.38 1.95375 32.3
2 75.195 0.20
3 16.091 5.99 1.65 160 58.5
4 60.195 1.00 1.80518 25.4
5 11.199 4.97
6 (Aperture) ∞ 1.77
7 -54.721 1.99 1.88300 40.8
8 -24.700 1.00 1.89286 20.4
9 -40.223 2.62
10 -21.337 3.50 1.48749 70.2
11 -65.931 4.65
12 205.798 5.55 1.85060 41.6
13 -38.304 19.45
14 ∞ 1.40 1.55900 60.0
15 ∞ 0.59
Image plane ∞
Focal length 48.70
F number 1.85
Half angle of view (degrees) 23.95
Statue height 21.64
Total lens length 58.55
BF 20.94
［数値実施例３］
単位 mm
面データ
面番号 r d nd vd
1 26.309 4.39 1.89190 37.1
2 82.686 0.20
3 18.140 5.17 1.63854 55.4
4 65.265 1.00 1.85478 24.8
5 14.120 5.21
6(絞り) ∞ 5.14
7 -17.080 1.00 1.67270 32.1
8 60.676 4.66 1.89190 37.1
9 -21.096 6.43
10 -14.841 1.20 1.51823 58.9
11 -28.232 0.15
12 109.535 6.28 1.63854 55.4
13 -43.748 16.25
14 ∞ 1.40 1.55900 60.0
15 ∞ 0.59
像面 ∞
焦点距離 48.74
Ｆナンバー 1.85
半画角（度） 23.94
像高 21.64
レンズ全長 58.55
BF 17.74
[Numerical Example 3]
Unit mm
Surface data surface number rd nd vd
1 26.309 4.39 1.89190 37.1
2 82.686 0.20
3 18.140 5.17 1.63854 55.4
4 65.265 1.00 1.85478 24.8
5 14.120 5.21
6 (Aperture) ∞ 5.14
7 -17.080 1.00 1.67270 32.1
8 60.676 4.66 1.89190 37.1
9 -21.096 6.43
10 -14.841 1.20 1.51823 58.9
11 -28.232 0.15
12 109.535 6.28 1.63854 55.4
13 -43.748 16.25
14 ∞ 1.40 1.55900 60.0
15 ∞ 0.59
Image plane ∞
Focal length 48.74
F number 1.85
Half angle of view (degrees) 23.94
Statue height 21.64
Total lens length 58.55
BF 17.74
［数値実施例４］
単位 mm
面データ
面番号 r d nd vd
1 27.227 4.95 1.89190 37.1
2 77.440 0.20
3 16.602 5.81 1.71999 50.2
4 61.835 1.20 1.85478 24.8
5 11.628 5.54
6(絞り) ∞ 7.25
7 -16.179 1.00 1.72047 34.7
8 -34.425 2.89 1.85150 40.8
9 -18.805 1.00
10 -17.488 1.23 1.48749 70.2
11 -23.537 0.98
12 101.584 6.35 1.69680 55.5
13 -42.236 18.65
14 ∞ 1.40 1.55900 60.0
15 ∞ 0.60
像面 ∞
焦点距離 48.70
Fナンバー 1.85
画角 23.95
像高 21.64
レンズ全長 58.55
BF 20.15
[Numerical Example 4]
Unit mm
Surface data surface number rd nd vd
1 27.227 4.95 1.89190 37.1
2 77.440 0.20
3 16.602 5.81 1.71999 50.2
4 61.835 1.20 1.85478 24.8
5 11.628 5.54
6 (Aperture) ∞ 7.25
7 -16.179 1.00 1.72047 34.7
8 -34.425 2.89 1.85 150 40.8
9 -18.805 1.00
10 -17.488 1.23 1.48749 70.2
11 -23.537 0.98
12 101.584 6.35 1.69680 55.5
13 -42.236 18.65
14 ∞ 1.40 1.55900 60.0
15 ∞ 0.60
Image plane ∞
Focal length 48.70
F number 1.85
Angle of view 23.95
Statue height 21.64
Total lens length 58.55
BF 20.15
［数値実施例５］
単位 mm
面データ
面番号 r d nd vd
1 25.922 5.25 1.71300 53.9
2 100.067 0.20
3 16.060 4.22 1.80610 40.9
4 27.655 0.44
5 31.067 1.20 1.85478 24.8
6 11.906 5.84
7(絞り) ∞ 4.45
8 -20.163 1.00 1.59270 35.3
9 58.203 4.31 1.83400 37.2
10 -21.052 2.05
11 -17.022 1.23 1.69895 30.1
12 -28.469 6.95
13 158.522 4.93 1.71999 50.2
14 -58.485 15.00
15 ∞ 1.40 1.55900 60.0
16 ∞ 0.59
像面 ∞
焦点距離 48.70
Ｆナンバー 1.85
半画角（度） 23.95
像高 21.64
レンズ全長 58.55
BF 16.48
[Numerical Example 5]
Unit mm
Surface data surface number rd nd vd
1 25.922 5.25 1.71300 53.9
2 100.067 0.20
3 16.060 4.22 1.80610 40.9
4 27.655 0.44
5 31.067 1.20 1.85478 24.8
6 11.906 5.84
7 (Aperture) ∞ 4.45
8 -20.163 1.00 1.59270 35.3
9 58.203 4.31 1.83400 37.2
10 -21.052 2.05
11 -17.022 1.23 1.69895 30.1
12 -28.469 6.95
13 158.522 4.93 1.71999 50.2
14 -58.485 15.00
15 ∞ 1.40 1.55900 60.0
16 ∞ 0.59
Image plane ∞
Focal length 48.70
F number 1.85
Half angle of view (degrees) 23.95
Statue height 21.64
Total lens length 58.55
BF 16.48
［数値実施例６］
単位 mm
面データ
面番号 r d nd vd
1 25.396 5.80 1.65160 58.5
2 108.471 0.20
3 16.442 4.40 1.90043 37.4
4 31.474 0.38
5 34.907 1.20 1.85478 24.8
6 11.628 5.78
7(絞り) ∞ 6.01
8 -16.511 2.72 1.95375 32.3
9 -13.235 0.43
10 -12.498 1.23 1.74077 27.6
11 -22.656 5.00
12 98.455 6.02 1.73350 51.8
13 -48.653 17.89
14 ∞ 1.40 1.55900 60.0
15 ∞ 0.60
像面 ∞
焦点距離 48.70
Ｆナンバー 1.85
半画角（度） 23.95
像高 21.64
レンズ全長 58.55
BF 19.38
[Numerical Example 6]
Unit mm
Surface data surface number rd nd vd
1 25.396 5.80 1.65160 58.5
2 108.471 0.20
3 16.442 4.40 1.90043 37.4
4 31.474 0.38
5 34.907 1.20 1.85478 24.8
6 11.628 5.78
7 (Aperture) ∞ 6.01
8 -16.511 2.72 1.95375 32.3
9 -13.235 0.43
10 -12.498 1.23 1.74077 27.6
11 -22.656 5.00
12 98.455 6.02 1.73350 51.8
13 -48.653 17.89
14 ∞ 1.40 1.55900 60.0
15 ∞ 0.60
Image plane ∞
Focal length 48.70
F number 1.85
Half angle of view (degrees) 23.95
Statue height 21.64
Total lens length 58.55
BF 19.38
［撮像装置の実施例］
次に、本発明の光学系を撮影光学系として用いた撮像装置の実施例について図１３を用いて説明する。撮像装置１０は、例えば、デジタルスチルカメラ、デジタルビデオカメラ、監視カメラ、放送用カメラ等の撮像素子を用いた撮像装置、または銀塩写真フィルムを用いたカメラ等の撮像装置である。
[Example of imaging apparatus]
Next, an embodiment of an imaging apparatus using the optical system of the present invention as a photographing optical system will be described with reference to FIG. The
図１３において、撮像装置１０は、実施例１〜６で説明した光学系のいずれかである撮影光学系１１と、撮像装置１０に内蔵され且つ撮影光学系１１によって形成された被写体像を受光する撮像素子（光電変換素子）１２とを有する。撮像素子１２は、例えばＣＣＤセンサやＣＭＯＳセンサ等である。
In FIG. 13, the
このように本発明の光学系を各種撮像装置の撮影光学系として適用することができる。これにより、小型で高い光学性能を有する撮像装置を得ることができる。 Thus, the optical system of the present invention can be applied as a photographing optical system for various imaging apparatuses. Thereby, an image pickup apparatus having a small size and high optical performance can be obtained.
以上、本発明の好ましい実施例について説明したが、本発明の光学系及び撮像装置はこれらの実施例に限定されず、その要旨の範囲内で種々の変形及び変更が可能である。例えば、光学系の一部のレンズを光軸に対して垂直方向の成分を含む方向に移動させることによって、像ぶれ補正を行ってもよい。 The preferred embodiments of the present invention have been described above. However, the optical system and the imaging apparatus of the present invention are not limited to these embodiments, and various modifications and changes can be made within the scope of the gist. For example, image blur correction may be performed by moving some lenses of the optical system in a direction including a component in a direction perpendicular to the optical axis.
Ｂ１ 第１レンズ群
Ｂ２ 第２レンズ群
Ｌｐ１ 第１正レンズ
Ｌｐ２ 第２正レンズ
Ｌｐ３ 第３正レンズ
Ｌｎ１ 第１負レンズ
Ｌｎ２ 第２負レンズ
ＯＰ 光学系
B1 1st lens group B2 2nd lens group Lp1 1st positive lens Lp2 2nd positive lens Lp3 3rd positive lens Ln1 1st negative lens Ln2 2nd negative lens OP Optical system
Claims (14)
前記複数のレンズ群は、前記開口絞りの物体側に配置された正の屈折力の第１レンズ群と、前記開口絞りの像側に配置された正の屈折力の第２レンズ群からなり、
前記第１レンズ群は、物体側から像側へ順に配置された、第１正レンズ、第２正レンズ、第１負レンズからなり、
前記第２レンズ群は、物体側から像側へ順に配置された、少なくとも１枚のレンズ、第２負レンズ、第３正レンズからなり、
前記第１レンズ群の焦点距離をｆ１、前記第２レンズ群の焦点距離をｆ２、とするとき、
０．５０＜ｆ１／ｆ２＜１．６５
なる条件式を満たすことを特徴とする光学系。 An optical system having a plurality of lens groups and an aperture stop,
The plurality of lens groups includes a first lens unit having a positive refractive power disposed on the object side of the aperture stop and a second lens group having a positive refractive power disposed on the image side of the aperture stop,
The first lens group includes a first positive lens, a second positive lens, and a first negative lens arranged in order from the object side to the image side,
The second lens group includes at least one lens, a second negative lens, and a third positive lens arranged in order from the object side to the image side,
When the focal length of the first lens group is f1, and the focal length of the second lens group is f2,
0.50 <f1 / f2 <1.65
An optical system characterized by satisfying the following conditional expression:
１．５０＜｜ｆｎ２｜／ｓｋ＜１０．００
なる条件式を満たすことを特徴とする請求項１に記載の光学系。 When the focal length of the second negative lens is fn2 and the back focus of the optical system is sk,
1.50 <| fn2 | / sk <10.00
The optical system according to claim 1, wherein the following conditional expression is satisfied.
０．７０＜｜ｆｎ２｜／ｆ＜３．３０
なる条件式を満たすことを特徴とする請求項１又は２に記載の光学系。 When the focal length of the second negative lens is fn2 and the focal length of the optical system is f,
0.70 <| fn2 | / f <3.30
The optical system according to claim 1, wherein the following conditional expression is satisfied.
０．７５＜Ｌｓ／ｆ＜０．９５
なる条件式を満たすことを特徴とする請求項１乃至３のいずれか１項に記載の光学系。 When the distance on the optical axis from the aperture stop to the image plane at the time of focusing on infinity is Ls, and the focal length of the optical system is f,
0.75 <Ls / f <0.95
The optical system according to claim 1, wherein the following conditional expression is satisfied.
０．７０＜Ｔｄ／ｆ＜１．００
なる条件式を満たすことを特徴とする請求項１乃至４のいずれか１項に記載の光学系。 The distance on the optical axis from the object-side lens surface of the first positive lens to the image-side lens surface of the third positive lens during infinite focus is Td, and the focal length of the optical system is f. When
0.70 <Td / f <1.00
The optical system according to claim 1, wherein the following conditional expression is satisfied.
０．７０＜｜ｆｎ２｜／ｆｐ３＜４．００
なる条件式を満たすことを特徴とする請求項１乃至５のいずれか１項に記載の光学系。 When the focal length of the second negative lens is fn2, and the focal length of the third positive lens is fp3,
0.70 <| fn2 | / fp3 <4.00
The optical system according to claim 1, wherein the following conditional expression is satisfied.
０．８０＜ｆ１／ｆ＜１．７０
なる条件式を満たすことを特徴とする請求項１乃至６のいずれか１項に記載の光学系。 When the focal length of the optical system is f,
0.80 <f1 / f <1.70
The optical system according to claim 1, wherein the following conditional expression is satisfied.
０．７５＜ｆｐ１／ｆ＜１．２０
なる条件式を満たすことを特徴とする請求項１乃至７のいずれか１項に記載の光学系。 When the focal length of the first positive lens is fp1, and the focal length of the optical system is f,
0.75 <fp1 / f <1.20
The optical system according to claim 1, wherein the following conditional expression is satisfied.
０．２５＜｜ｆｎ１｜／ｆ＜０．６
なる条件式を満たすことを特徴とする請求項１乃至８のいずれか１項に記載の光学系。 When the focal length of the first negative lens is fn1, and the focal length of the optical system is f,
0.25 <| fn1 | / f <0.6
The optical system according to claim 1, wherein the following conditional expression is satisfied.
０．５０＜ｆｐ１／ｆｐ３＜１．２５
なる条件式を満たすことを特徴とする請求項１乃至９のいずれか１項に記載の光学系。 When the focal length of the first positive lens is fp1, and the focal length of the third positive lens is fp3,
0.50 <fp1 / fp3 <1.25
The optical system according to claim 1, wherein the following conditional expression is satisfied.
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| CN112269246A (en) * | 2020-12-14 | 2021-01-26 | 宁波永新光学股份有限公司 | Ultra-high-definition imaging optical system |
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