JP2011081111A - Rear attachment lens and imaging optical system including the same - Google Patents
Rear attachment lens and imaging optical system including the same Download PDFInfo
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本発明は、デジタルスチルカメラやビデオカメラ、放送用カメラなどに用いられる撮影レンズ（主レンズ系）の像側に着脱可能に装着して、全系の焦点距離を主レンズ系の本来の焦点距離に比べて長い方へ変化させるリアアタッチメントレンズに関する。 The present invention is detachably mounted on the image side of a photographic lens (main lens system) used in a digital still camera, a video camera, a broadcast camera, etc., and the focal length of the entire system is the original focal length of the main lens system. It is related with the rear attachment lens which changes to the long one compared with.
従来より、撮影レンズ（撮影光学系）である主レンズ系の像側に着脱可能に装着し、主レンズ系単独の焦点距離に比べて全系の焦点距離を長い方へ変化させるリアアタッチメントレンズが知られている（特許文献１〜３）。 Conventionally, there has been a rear attachment lens that is detachably attached to the image side of the main lens system, which is a photographic lens (photographing optical system), and changes the focal length of the entire system to be longer than the focal length of the main lens system alone. It is known (patent documents 1 to 3).
特許文献１〜３には主レンズ系の像側に装着し、主レンズ系の焦点距離を長焦点距離側へ拡大可能なリアアタッチメントレンズが開示されている。 Patent Documents 1 to 3 disclose rear attachment lenses that are attached to the image side of the main lens system and can expand the focal length of the main lens system to the long focal length side.
リアアタッチメントレンズを使用することの多い望遠レンズでは、焦点距離が長くなるに従って、諸収差のうち特に色収差が劣化する傾向にある。その為、リアアタッチメントレンズを望遠レンズより成る主レンズ系に装着した場合は、主レンズ系の倍率色収差が拡大され、このときの拡大された倍率色収差が画質を劣化させる主原因となっている。 In a telephoto lens that often uses a rear attachment lens, chromatic aberration, in particular, tends to deteriorate as the focal length increases. For this reason, when the rear attachment lens is mounted on a main lens system including a telephoto lens, the chromatic aberration of magnification of the main lens system is enlarged, and the enlarged chromatic aberration of magnification at this time is a main cause of deteriorating image quality.
本発明は主レンズ系の像側に装着し、全系の焦点距離を長くしたときの諸収差の変動が少なく、特に色収差の変動が小さく、全系として高い光学性能を維持することができるリアアタッチメントレンズを提供することを目的とする。 The present invention is mounted on the image side of the main lens system, and the variation of various aberrations when the focal length of the entire system is increased is small, especially the variation of chromatic aberration is small, and the rear that can maintain high optical performance as the entire system. An object is to provide an attachment lens.
本発明のリアアタッチメントレンズは、主レンズ系の像側に着脱可能に装着され、該主レンズ系単独の焦点距離に比べて長い方へ焦点距離を変化させるリアアタッチメントレンズにおいて、前記リアアタッチメントレンズの最も物体側のレンズ面から最も像側のレンズ面までの距離をＬとするとき、前記リアアタッチメントレンズの最も物体側のレンズ面からの距離が０．５Ｌから１．０Ｌまでの間に負レンズGn1を有しており、前記負レンズGn1は材料のｄ線に対するアッベ数をνdn1、ｇ線とＦ線に対する部分分散比をθgFn1とするとき、
10＜νdn1＜23
0.020＜θgFn1−0.6438＋0.001682×νdn1＜0.100
なる条件を満足していることを特徴としている。
The rear attachment lens of the present invention is detachably mounted on the image side of the main lens system, and the rear attachment lens changes the focal length in a longer direction than the focal length of the main lens system alone. When the distance from the lens surface closest to the object side to the lens surface closest to the image side is L, a negative lens is used when the distance from the lens surface closest to the object side of the rear attachment lens is 0.5L to 1.0L. When the negative lens Gn1 has an Abbe number of the material with respect to the d-line νdn1 and a partial dispersion ratio with respect to the g-line and the F-line θgFn1,
10 <νdn1 <23
0.020 <θgFn1−0.6438 + 0.001682 × νdn1 <0.100
It is characterized by satisfying the following conditions.
本発明によれば主レンズ系の像側に装着し、全系の焦点距離を長くしたときの諸収差の変動が小さく、特に色収差の変動が小さく、全系として高い光学性能を維持することができるリアアタッチメントレンズが得られる。 According to the present invention, when mounted on the image side of the main lens system and the focal length of the entire system is increased, fluctuations in various aberrations are small, especially fluctuations in chromatic aberration are small, and high optical performance as a whole system can be maintained. A rear attachment lens that can be obtained is obtained.
本発明のリアアタッチメントレンズ及びそれを主レンズ系に装着したときの撮影光学系及び該撮影光学系を用いた撮像装置について説明する。本発明のリアアタッチメントレンズは、主レンズ系の像側に着脱可能に装着され、主レンズ系単独の焦点距離に比べて長い方へ焦点距離を変化させる。ここで主レンズ系としては、例えば望遠レンズ、望遠型のズームレンズ等が適用できる。 A rear attachment lens of the present invention, a photographing optical system when the rear attachment lens is mounted on a main lens system, and an image pickup apparatus using the photographing optical system will be described. The rear attachment lens of the present invention is detachably mounted on the image side of the main lens system, and changes the focal length in a longer direction than the focal length of the main lens system alone. Here, as the main lens system, for example, a telephoto lens, a telephoto zoom lens, or the like can be applied.
図１、図２は、本発明の各実施例のリアアタッチメントレンズが装着される、一例としての主レンズ系（望遠レンズ）のレンズ断面図と収差図である。図３、図４は各々本発明の実施例１のリアアタッチメントレンズを主レンズ系の像側に装着したときのレンズ断面図と収差図である。図５、図６は各々本発明の実施例２のリアアタッチメントレンズを主レンズ系の像側に装着したときのレンズ断面図と収差図である。図７、図８は各々本発明の実施例３のリアアタッチメントレンズを主レンズ系の像側に装着したときのレンズ断面図と収差図である。 FIGS. 1 and 2 are a lens cross-sectional view and aberration diagrams of a main lens system (telephoto lens) as an example to which the rear attachment lens of each embodiment of the present invention is attached. FIGS. 3 and 4 are a lens cross-sectional view and an aberration diagram when the rear attachment lens of Example 1 of the present invention is mounted on the image side of the main lens system, respectively. 5 and 6 are a lens cross-sectional view and an aberration diagram when the rear attachment lens of Example 2 of the present invention is mounted on the image side of the main lens system, respectively. 7 and 8 are a lens cross-sectional view and an aberration diagram when the rear attachment lens of Example 3 of the present invention is mounted on the image side of the main lens system, respectively.
レンズ断面図において、左方が物体側で、右方が像側である。ＬＡはリアアタッチメントレンズ、Ｒｓはリアアタッチメントレンズの最も物体側のレンズ面、Ｒｅはリアアタッチメントレンズの最も像側のレンズ面（最終レンズ面）である。ＬＭは主レンズ系（マスターレンズ）である。主レンズ系ＬＭは単一の焦点距離の望遠レンズである。Ｓは開口絞りである。Ｇは保護ガラス等に相当する光学ブロックである。ＩＰは像面であり、ビデオカメラやデジタルカメラの撮影光学系として使用する際には像を受光するＣＣＤセンサやＣＭＯＳセンサ等の固体撮像素子（光電変換素子）の撮像面に相当する。また、銀塩フィルム用カメラの撮像光学系として使用する際にはフィルム面に相当する。収差図において、ｄ、ｇ、Ｃ、Ｆはそれぞれ順にｄ線、ｇ線、Ｃ線、Ｆ線である。ｄＭ、ｄＳはそれぞれ順にメリジオナル像面、サジタル像面である。倍率色収差はｇ線によって表している。ＦｎｏはＦナンバー、Ｙは像高である。 In the lens cross-sectional view, the left side is the object side, and the right side is the image side. LA is a rear attachment lens, Rs is a lens surface on the most object side of the rear attachment lens, and Re is a lens surface (final lens surface) on the most image side of the rear attachment lens. LM is a main lens system (master lens). The main lens system LM is a telephoto lens having a single focal length. S is an aperture stop. G is an optical block corresponding to protective glass or the like. IP denotes an image plane, which corresponds to an imaging plane of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor that receives an image when used as a photographing optical system of a video camera or a digital camera. Moreover, when using as an imaging optical system of the camera for silver salt films, it corresponds to a film surface. In the aberration diagrams, d, g, C, and F are d-line, g-line, C-line, and F-line, respectively. dM and dS are a meridional image plane and a sagittal image plane, respectively. Lateral chromatic aberration is represented by the g-line. Fno is the F number, and Y is the image height.
次に本発明に係る撮影光学系に用いる光学材料の分散特性の一般的な特徴について述べる。本実施例の撮影光学系に用いるレンズの材料の部分分散比とアッベ数は次の通りである。フラウンフォーファ線のｇ線(波長４３５．８ｎｍ）、Ｆ線(波長４８６．１ｎｍ）、ｄ線(波長５８７．６ｎｍ）、Ｃ線(波長６５６．３ｎｍ）に対する屈折率をそれぞれＮｇ、ＮＦ、Ｎｄ，ＮＣとする。アッベ数νｄ、ｇ線とＦ線に関する部分分散比θgFは次の通りである。 Next, general characteristics of the dispersion characteristics of the optical material used in the photographing optical system according to the present invention will be described. The partial dispersion ratio and Abbe number of the lens material used in the photographing optical system of the present embodiment are as follows. The refractive index of the Fraunhofer line for g-line (wavelength 435.8 nm), F-line (wavelength 486.1 nm), d-line (wavelength 587.6 nm), and C-line (wavelength 656.3 nm) is Ng, NF, respectively. Let Nd, NC. The partial dispersion ratio θgF for the Abbe number νd, g-line and F-line is as follows.
νd＝（Nd−１）／（NF−NC）
θgF＝（Ng−NF）／（NF−NC）
光学材料の屈折率の波長特性（分散特性）において、アッベ数の逆数1/νdの増加に伴い、分散特性曲線におけるＦ線〜Ｃ線間の全体の傾きが大きくなる。また、部分分散比θgFの増加に伴い、分散特性曲線のＦ線〜Ｃ線間の傾きに対するｇ線〜Ｆ線間の傾き（短波長側の曲がり具合）が大きくなる。
νd = (Nd−1) / (NF−NC)
θgF = (Ng−NF) / (NF−NC)
In the wavelength characteristic (dispersion characteristic) of the refractive index of the optical material, as the reciprocal 1 / νd of the Abbe number increases, the overall slope between the F line and the C line in the dispersion characteristic curve increases. As the partial dispersion ratio θgF increases, the slope between the g-line and the F-line (the degree of bending on the short wavelength side) with respect to the slope between the F-line and the C-line of the dispersion characteristic curve increases.
一般的に光学材料は、短波長側の屈折率が長波長側の屈折率よりも高く（アッベ数が正の値）、分散特性曲線は下に凸状（部分分散比が正の値）の軌跡を描き、短波長側になるほど波長の変化に対する屈折率の変化は大きくなる。光学材料として最も一般的に用いられる硝子材料においては、アッベ数の小さい高分散な光学材料ほど部分分散比が大きく、分散特性曲線は下に凸状が強まり、アッベ数の大きい低分散な光学材料ほど部分分散比が小さく、分散特性曲線は直線に近い傾向を示す。 In general, an optical material has a refractive index on the short wavelength side higher than a refractive index on the long wavelength side (Abbe number is a positive value), and the dispersion characteristic curve is convex downward (a partial dispersion ratio is a positive value). A trace is drawn, and the shorter the wavelength, the greater the change in refractive index with respect to the change in wavelength. Of the glass materials most commonly used as an optical material, a high dispersion optical material with a smaller Abbe number has a higher partial dispersion ratio, and the dispersion characteristic curve has a downward convex shape, and a low dispersion optical material with a large Abbe number. The partial dispersion ratio is so small that the dispersion characteristic curve tends to be a straight line.
以上を踏まえた上で本発明のリアアタッチメントレンズの色収差の補正原理について説明する。一般にリアアタッチメントレンズは、それ自体が無収差となるように設計されていたとしても、拡大倍率に比例して主レンズの残存収差を拡大し、画質を劣化させている。例えば、拡大倍率が２倍であった場合は、単純に、コマ収差や倍率色収差等の横収差は２倍に拡大され、画質が劣化する。また、球面収差や像面湾曲、そして軸上色収差等の縦収差においても、２倍に拡大され、画質が劣化する。厳密に言うと、縦収差自体は、拡大倍率の自乗倍、つまり４倍に拡大されるが、主レンズのＦナンバーも２倍に拡大（暗くなる方向）される為、単位焦点深度当たりの収差は、結局２倍に拡大されて劣化していくことになる。主レンズ系の焦点距離を長焦点距離側に拡大するリアアタッチメントレンズは、負の屈折力を有している。 Based on the above, the principle of correcting chromatic aberration of the rear attachment lens of the present invention will be described. In general, even if the rear attachment lens is designed to be free of aberrations, the residual aberration of the main lens is enlarged in proportion to the magnification and the image quality is deteriorated. For example, when the enlargement magnification is twice, lateral aberrations such as coma and chromatic aberration of magnification are simply doubled and image quality deteriorates. Also, longitudinal aberrations such as spherical aberration, curvature of field, and longitudinal chromatic aberration are magnified by a factor of 2 and image quality deteriorates. Strictly speaking, the longitudinal aberration itself is magnified to the square of the magnification, that is, 4 times, but the F number of the main lens is also magnified twice (in the direction of darkening), so the aberration per unit depth of focus. Will eventually be doubled and deteriorated. The rear attachment lens that expands the focal length of the main lens system to the long focal length side has negative refractive power.
従来のリアアタッチメントレンズでは、負の屈折力で発生する軸上色収差を効果的に補正するべく、正レンズに高分散な光学材料を用い、負レンズに低分散な光学材料が主に用いられていた。ところが、リアアタッチメントが装着される位置は、軸外主光線の入射高ｈ-が大きい位置であるため、高分散材料より成る正レンズ、低分散材料より成る負レンズを使用したとき、Ｃ線の倍率色収差が外側に、Ｆ線とｇ線の倍率色収差が内側に大きく発生してしまう。そのため、従来のリアアタッチメントレンズは、主レンズ系に残存する倍率色収差を拡大するだけでなく、それ自体に倍率色収差を大きく劣化させる要素を含んでいた。このため、リアアタッチメントレンズを装着すると著しく画質を劣化させていた。 In a conventional rear attachment lens, a high-dispersion optical material is mainly used for a positive lens and a low-dispersion optical material is mainly used for a negative lens in order to effectively correct axial chromatic aberration caused by negative refractive power. It was. However, the position where the rear attachment is mounted is a position where the incident height h− of the off-axis principal ray is large. Therefore, when a positive lens made of a high dispersion material and a negative lens made of a low dispersion material are used, The lateral chromatic aberration is greatly generated on the outside, and the lateral chromatic aberration of the F-line and the g-line is largely generated on the inside. For this reason, the conventional rear attachment lens not only expands the lateral chromatic aberration remaining in the main lens system, but also includes an element that greatly degrades the lateral chromatic aberration. For this reason, when the rear attachment lens is attached, the image quality is remarkably deteriorated.
そこで本発明では、軸上光線の入射高ｈが小さく、軸外主光線の入射高ｈ-が大きくなる像側に、強い高分散性を有する材料より成る負レンズを配置している。これにより軸上色収差を過剰発生させることなく、Ｃ線の倍率色収差を内側に、Ｆ線とｇ線を外側に発生させている。それにより、軸上色収差と倍率色収差を共に良好に補正することができるようにしている。 Therefore, in the present invention, a negative lens made of a material having strong high dispersibility is arranged on the image side where the incident height h of the on-axis light beam is small and the incident height h- of the off-axis principal ray is large. As a result, the lateral chromatic aberration of the C line is generated on the inner side, and the F line and the g line are generated on the outer side without causing excessive axial chromatic aberration. Thereby, both axial chromatic aberration and lateral chromatic aberration can be corrected satisfactorily.
さらに、強い高分散性の材料より成る負レンズで幾分劣化した軸上色収差を良好に補正するため、軸上光線の入射高ｈが大きく、軸外光線の入射高ｈ-が比較的小さい物体側に、高分散の材料より成る正レンズを配置するのが好ましい。 Furthermore, in order to satisfactorily correct the slightly deteriorated axial chromatic aberration with a negative lens made of a strong, highly dispersive material, an object with a large incident height h of on-axis rays and a relatively small incidence height h- of off-axis rays. A positive lens made of a highly dispersed material is preferably arranged on the side.
さらに、軸上光線の入射高ｈが小さく、軸外主光線の入射高ｈ-が大きい像側に、高分散でありながら、比較的部分分散比が小さい、例えばＮｂ２Ｏ３(酸化ニオブ）を主原料とする材料より成る正レンズを配置するのが好ましい。これにより、ｇ線の倍率色収差を良好に補正している。Ｎｂ２Ｏ３を主原料とする材料は、最も一般的な高分散な光学材料であるＴｉO2(酸化チタン）を主原料とする材料に対し、やや低分散ではあるが、部分分散比が比較的小さい特性を有している。 Further, on the image side where the incident height h of the on-axis light beam is small and the incident height h− of the off-axis principal ray is large, the partial dispersion ratio is relatively small, for example, Nb 2 O 3 (niobium oxide). It is preferable to dispose a positive lens made of a material whose main material is. Thereby, the lateral chromatic aberration of g-line is corrected well. The material with Nb 2 O 3 as the main raw material is slightly lower dispersion than the material with TiO 2 (titanium oxide) as the main raw material, the most common high-dispersion optical material, but the partial dispersion ratio is comparative It has small characteristics.
次に以上の条件を実現する具体的な構成について説明する。本発明のリアアタッチメントレンズでは、軸上光線の入射高ｈが低く、軸外主光線の入射高ｈ-が高い、像側の負レンズに、高分散かつ部分分散比の大きい材料を用いることで、軸上色収差を劣化することなく、倍率色収差を良好に補正している。 Next, a specific configuration for realizing the above conditions will be described. In the rear attachment lens of the present invention, a high-dispersion and high-partial-dispersion ratio material is used for the negative lens on the image side where the incident height h of the on-axis ray is low and the incident height h− of the off-axis principal ray is high. The lateral chromatic aberration is corrected well without deteriorating the longitudinal chromatic aberration.
具体的には、リアアタッチメントレンズの最も物体側のレンズ面から最も像側のレンズ面までの距離をＬとするとき、リアアタッチメントレンズの最も物体側のレンズ面からの距離が０．５Ｌから１．０Ｌまでの間に負レンズGn1を配置した。負レンズGn1は材料のｄ線に対するアッベ数をνdn1、ｇ線とＦ線に対する部分分散比をθgFn1とするとき、
10＜νdn1＜23・・・（1）
0.020＜θgFn1−0.6438＋0.001682×νdn1＜0.100・・・（2）
なる条件を満足している。ここで、距離０．５Ｌから１．０Ｌまでの間に負レンズを配置するとは、この距離の間にレンズが全て含まれることを言う。
Specifically, when the distance from the lens surface closest to the object side to the lens surface closest to the image side is L, the distance from the lens surface closest to the object side of the rear attachment lens is 0.5L to 1. The negative lens Gn1 was placed up to 0.0L. The negative lens Gn1 has a Abbe number of the material with respect to the d-line as νdn1, and a partial dispersion ratio with respect to the g-line and F-line as θgFn1
10 <νdn1 <23 (1)
0.020 <θgFn1−0.6438 + 0.001682 × νdn1 <0.100 (2)
Is satisfied. Here, disposing a negative lens between a distance of 0.5 L and 1.0 L means that all the lenses are included within this distance.
リアアタッチメントレンズの最も物体側のレンズ面からの距離が０．５Ｌよりも小さくなる位置に前記負レンズGn1が配置された場合、軸上光線の入射高ｈが高く、軸外主光線の入射高ｈ-が低くなる。したがって、倍率色収差の補正効果が弱まるだけでなく軸上色収差を劣化させるため良くない。 When the negative lens Gn1 is disposed at a position where the distance from the lens surface closest to the object side of the rear attachment lens is smaller than 0.5L, the incident height h of the on-axis ray is high and the incident height of the off-axis principal ray is high. h- is lowered. Accordingly, the correction effect of the lateral chromatic aberration is not only weakened, but the axial chromatic aberration is deteriorated, which is not good.
条件式（1）の上限値を逸脱すると、Ｃ線及びＦ線の倍率色収差を良好に補正することが困難となる。また、条件式（1）の下限値を逸脱すると、Ｃ線及びＦ線の倍率色収差補正には好ましいが、軸上色収差を劣化させるため良くない。 If the upper limit of conditional expression (1) is deviated, it will be difficult to satisfactorily correct the lateral chromatic aberration of the C-line and F-line. Further, if it deviates from the lower limit value of conditional expression (1), it is preferable for correcting chromatic aberration of magnification for C-line and F-line, but it is not good because it deteriorates axial chromatic aberration.
条件式（2）の上限値を逸脱すると、ｇ線の倍率色収差の補正には好ましいが、軸上色収差を劣化させるため良くない。また、条件式（2）の下限値を逸脱すると、ｇ線の倍率色収差の補正効果を良好に補正することが困難となる。さらに好ましくは上記条件式(1),(2)の数値範囲を次の如く設定するのが良い。 Deviating from the upper limit of conditional expression (2) is preferable for correcting the lateral chromatic aberration of g-line, but is not good because it degrades axial chromatic aberration. If the lower limit of conditional expression (2) is deviated, it will be difficult to satisfactorily correct the effect of correcting the lateral chromatic aberration of g-line. More preferably, the numerical ranges of the conditional expressions (1) and (2) are set as follows.
15＜νdn1＜23 ・・・（1a）
0.023＜θgFn1−0.6438＋0.001682×νdn1＜0.050・・・（2a）
本発明では、以上の手法により、軸上色収差及び倍率色収差を良好に補正するリアアタッチメントレンズを得ている。
15 <νdn1 <23 (1a)
0.023 <θgFn1−0.6438 + 0.001682 × νdn1 <0.050 (2a)
In the present invention, a rear attachment lens that satisfactorily corrects axial chromatic aberration and lateral chromatic aberration is obtained by the above-described method.
また、本発明において更に効果的に良好なる色収差特性を得るためには、次の条件のうち、少なくとも１つを満足するのが良い。 In order to obtain a more effective chromatic aberration characteristic in the present invention, at least one of the following conditions should be satisfied.
本発明の各実施例のリアアタッチメントレンズでは、前記負レンズGn1で劣化した軸上色収差を補正するべく、軸上光線の入射高ｈが高く、軸外主光線の入射高ｈ-が比較的低い物体側の正レンズに、高分散かつ部分分散比の比較的大きい材料を用いている。 In the rear attachment lens of each embodiment of the present invention, in order to correct the axial chromatic aberration deteriorated by the negative lens Gn1, the incident height h of the axial ray is high and the incident height h− of the off-axis principal ray is relatively low. A material having a high dispersion and a relatively large partial dispersion ratio is used for the positive lens on the object side.
具体的には、リアアタッチメントレンズの最も物体側のレンズ面からの距離が０から０．５Ｌまでの間に正レンズGp1を配置している。そして、前記正レンズGp1は材料のｄ線に対する屈折率とアッベ数を各々Ndp1、νdp1、ｇ線とＦ線に対する部分分散比をθgFp1とするとき、
1.90＜Ndp1＋0.0125νdp1＜2.24・・・（3）
0.001＜θgFp1−0.6438＋0.001682×νdp1＜0.020・・・（4）
なる条件を満足している。
Specifically, the positive lens Gp1 is disposed when the distance from the lens surface closest to the object side of the rear attachment lens is 0 to 0.5L. The positive lens Gp1 has a refractive index and Abbe number of the material for d-line of Ndp1, νdp1, and a partial dispersion ratio for g-line and F-line of θgFp1, respectively.
1.90 <Ndp1 + 0.0125νdp1 <2.24 (3)
0.001 <θgFp1−0.6438 + 0.001682 × νdp1 <0.020 (4)
Is satisfied.
リアアタッチメントレンズの最も物体側のレンズ面からの距離が０．５Ｌよりも大きくなる位置に前記正レンズGp1が配置された場合、軸上光線の入射高ｈが低く、軸外主光線の入射高ｈ-が高くなる。したがって、軸上色収差の補正効果が弱まるだけでなく倍率色収差を劣化させるため良くない。 When the positive lens Gp1 is disposed at a position where the distance from the lens surface closest to the object side of the rear attachment lens is greater than 0.5L, the incident height h of the on-axis ray is low and the incident height of the off-axis principal ray is low. h- becomes higher. Therefore, not only is the correction effect of axial chromatic aberration weakened, but also the lateral chromatic aberration is deteriorated.
条件式（3）の上限値を逸脱すると、アッベ数が大きい場合は前記負レンズGn1で発生したＣ線及びＦ線の軸上色収差を良好に補正することが難しくなり、屈折率が大きい場合は球面収差を良好に補正することが困難となるため良くない。また、条件式（3）の下限値を逸脱すると、加工が容易な材料を入手することが困難で、かつ樹脂材料等の加工困難な材料に限られるため、生産性を考慮した際、リアアタッチメントレンズに要望される良好な光学性能を安定して供給することが難しくなる。 If the upper limit of conditional expression (3) is deviated, if the Abbe number is large, it is difficult to satisfactorily correct the axial chromatic aberration of the C-line and F-line generated by the negative lens Gn1, and the refractive index is large. This is not good because it is difficult to correct spherical aberration well. Also, if you deviate from the lower limit value of conditional expression (3), it is difficult to obtain materials that are easy to process, and it is limited to materials that are difficult to process such as resin materials. It becomes difficult to stably supply the good optical performance required for the lens.
条件式（4）の上限値を逸脱すると、ｇ線の倍率色収差を劣化させるため良くない。また、条件式（4）の下限値を逸脱すると、ｇ線の軸上色収差の補正効果が弱まるため好ましくない。さらに好ましくは上記条件式(3),(4)の数値範囲を次の如く設定するのが良い。 If the upper limit of conditional expression (4) is deviated, the lateral chromatic aberration of g-line is deteriorated, which is not good. Further, if the value deviates from the lower limit value of conditional expression (4), the effect of correcting g-axis longitudinal chromatic aberration is weakened, which is not preferable. More preferably, the numerical ranges of the conditional expressions (3) and (4) are set as follows.
2.00＜Ndp1＋0.0125νdp1＜2.15・・・（3a）
0.001＜θgFp1−0.6438＋0.001682×νdp1＜0.015・・・（4a）
更に本発明の各実施例のリアアタッチメントレンズでは、軸上光線の入射高ｈが低く、軸外主光線の入射高ｈ-が高い像側の正レンズに、高分散でかつ部分分散比が比較的小さい材料を用いている。これによって、軸上色収差を劣化することなくｇ線の倍率色収差を良好に補正している。
2.00 <Ndp1 + 0.0125νdp1 <2.15 (3a)
0.001 <θgFp1−0.6438 + 0.001682 × νdp1 <0.015 (4a)
Furthermore, the rear attachment lens of each embodiment of the present invention has a high dispersion and a partial dispersion ratio compared to an image-side positive lens having a low incident height h of on-axis rays and a high incidence height h− of off-axis principal rays. Small material is used. As a result, the lateral chromatic aberration of the g-line is satisfactorily corrected without deteriorating the longitudinal chromatic aberration.
具体的には、リアアタッチメントレンズの最も物体側のレンズ面からの距離が０．５Ｌから１．０Ｌまでの間に正レンズGp2を配置している。そして、前記正レンズGp2は材料のｄ線に対する屈折率とアッベ数を各々Ndp2、νdp2、ｇ線とＦ線に対する部分分散比をθgFp2とするとき、
1.90＜Ndp2＋0.0125νdp2＜2.24・・・（5）
−0.010＜θgFp2−0.6438＋0.001682×νdp2＜0.003・・・（6）
なる条件を満足するのが良い。
Specifically, the positive lens Gp2 is disposed when the distance from the lens surface closest to the object side of the rear attachment lens is 0.5L to 1.0L. The positive lens Gp2 has a refractive index and Abbe number of the material for d-line of Ndp2, νdp2, and a partial dispersion ratio of g-line and F-line of θgFp2, respectively.
1.90 <Ndp2 + 0.0125νdp2 <2.24 (5)
−0.010 <θgFp2−0.6438 + 0.001682 × νdp2 <0.003 (6)
It is good to satisfy the condition.
リアアタッチメントレンズの最も物体側のレンズ面からの距離が０．５Ｌよりも小さくなる位置に前記正レンズGp2が配置された場合、軸上光線の入射高ｈが高く、軸外主光線の入射高ｈ-が低くなる。したがって、倍率色収差の補正効果が弱まるだけでなく、軸上色収差を劣化させるため良くない。 When the positive lens Gp2 is disposed at a position where the distance from the lens surface closest to the object side of the rear attachment lens is smaller than 0.5L, the incident height h of the on-axis ray is high and the incident height of the off-axis principal ray is high. h- is lowered. Therefore, not only the correction effect of the lateral chromatic aberration is weakened but also the axial chromatic aberration is deteriorated, which is not good.
条件式（5）の上限値を逸脱すると、アッベ数が大きい場合はＣ線及びＦ線の倍率色収差を良好に補正することが困難で、屈折率が大きい場合は像面湾曲が発生するため良くない。また、条件式（5）の下限値を逸脱すると、加工が容易な材料を入手することが困難で、かつ樹脂材料等の加工困難な材料に限られるため、生産性を考慮した際、リアアタッチメントレンズに要望される良好な光学性能を安定して供給することが難しい。 If the upper limit of conditional expression (5) is deviated, it is difficult to satisfactorily correct the lateral chromatic aberration of the C-line and F-line when the Abbe number is large, and the curvature of field occurs when the refractive index is large. Absent. Also, if you deviate from the lower limit value of conditional expression (5), it is difficult to obtain materials that are easy to process, and it is limited to materials that are difficult to process such as resin materials. It is difficult to stably supply the good optical performance required for the lens.
条件式（6）の上限値を逸脱すると、ｇ線の倍率色収差の補正効果を良好に補正することが困難となる。また、条件式（6）の下限値を逸脱すると、ｇ線の倍率色収差補正には好ましいが、軸上色収差を劣化させるため良くない。さらに好ましくは上記条件式(5),(6)の数値範囲を次の如く設定するのが良い。 If the upper limit of conditional expression (6) is deviated, it will be difficult to satisfactorily correct the effect of correcting the lateral chromatic aberration of g-line. Further, if it deviates from the lower limit value of conditional expression (6), it is preferable for correcting chromatic aberration of magnification for g-line, but it is not good because it degrades axial chromatic aberration. More preferably, the numerical ranges of the conditional expressions (5) and (6) are set as follows.
2.00＜Ndp2＋0.0125νdp2＜ 2.23・・・（5a）
−0.009＜θgFp2−0.6438＋0.001682×νdp2＜0.001・・・（6a）
また、前記正レンズGp2には、Ｎｂ２Ｏ３を主原料とする材料を使用している。先に述べた通り、Ｎｂ２Ｏ３を主原料とする材料を用いた理由は、一般的に使用されるＴｉO2を主原料とする材料よりも部分分散比の低いためであるが、色収差の補正効果以外に以下の効果も併せて得ている。
2.00 <Ndp2 + 0.0125νdp2 <2.23 (5a)
−0.009 <θgFp2−0.6438 + 0.001682 × νdp2 <0.001 (6a)
The positive lens Gp2 is made of a material mainly composed of Nb 2 O 3 . As described above, the reason why the material mainly made of Nb 2 O 3 is used is that the partial dispersion ratio is lower than that of the material mainly made of TiO 2 which is generally used. In addition to the correction effect, the following effects are also obtained.
通常、撮影光学系は、色再現を目指すため、光学系の透過光の色味を適当なバランスに保つ必要がある。それに対し、前記負レンズGn1において、現在市販の材料で条件式（1）、（2）を満たすものは、ＮｐＯ2（二酸化ネプツニウム）を主原料とする材料であり、青側の透過光の透過率が低い。 Usually, in order to aim at color reproduction, a photographing optical system needs to keep the color of transmitted light of the optical system in an appropriate balance. On the other hand, in the negative lens Gn1, materials that satisfy the conditional expressions (1) and (2) among the commercially available materials are materials mainly composed of NpO 2 (neptunium dioxide), and transmit blue-side transmitted light. The rate is low.
本発明では、前記ＮｐＯ2を使用しても透過光の色味の変化を軽度にするべく、光学系中で中心肉厚を薄くしやすい、外径が比較的小さい負レンズGn1に配置することで、透過光の黄色側へのシフトを軽減している。それでも尚、ＮｐＯ2を主原料とする材料を使用した際、透過光は黄色側にシフトする傾向にあるため、本発明では光学系全体の透過光を白色に近づけるべく、高分散の材料よりなる正レンズに着目した。 In the present invention, even if NpO 2 is used, in order to make the change in the color of transmitted light light, the central thickness is easily reduced in the optical system, and the negative lens Gn1 having a relatively small outer diameter is disposed. Therefore, the shift of the transmitted light to the yellow side is reduced. Nevertheless, when a material containing NpO 2 as a main material is used, the transmitted light tends to shift to the yellow side. Therefore, in the present invention, the entire optical system is made of a highly dispersed material so that the transmitted light approaches white. Focused on the positive lens.
通常、リアアタッチメントレンズの高分散材料よりなる正レンズは、肉厚が厚くなる上に、従来は青側の透過光の透過率がやや低いＴｉＯ2を主原料とする材料が使用されていた。そこで、ＴｉＯ2に比べて青側の透過光の透過率が比較的高いＮｂ２Ｏ３を主原料とする材料を使用することで、ＮｐＯ2を用いた際の青側の透過光の透過率の劣化を補償し、光学系全体の色味変化を従来同等に抑えている。 Normally, a positive lens made of a highly dispersed material for a rear attachment lens is thick, and conventionally, a material mainly made of TiO 2 having a slightly low transmittance of transmitted light on the blue side has been used. Therefore, the transmittance of blue-side transmitted light when NpO 2 is used by using a material mainly made of Nb 2 O 3 which has a relatively high transmittance of blue-side transmitted light compared to TiO 2. Is compensated for, and the color change of the entire optical system is suppressed to the same level as before.
次に主レンズ系及び実施例１から３に対応する数値実施例１から３を示す。数値実施例１から３については、リアアタッチメント部のデータのみ示しており、第１面の空気間隔が、主レンズ系の最も像側のレンズ面からリアアタッチメントレンズの最も物体側のレンズ面Ｒｓまでの間隔を示している。数値実施例１から３における主レンズ系は、焦点距離300ｍｍの各収差が十分良好に補正された望遠レンズを使用している。よって、この主レンズ系にリアアタッチメントレンズをつけた状態で、各収差が良好に補正されていれば、他のレンズ系に装着した場合も、元の性能に対して良好な特性を得ることが出来る。 Next, numerical examples 1 to 3 corresponding to the main lens system and Examples 1 to 3 will be described. In the numerical examples 1 to 3, only the data of the rear attachment part is shown, and the air spacing of the first surface is from the most image side lens surface of the main lens system to the most object side lens surface Rs of the rear attachment lens. The interval is shown. The main lens system in Numerical Examples 1 to 3 uses a telephoto lens in which each aberration with a focal length of 300 mm is sufficiently satisfactorily corrected. Therefore, if each aberration is well corrected with the rear attachment lens attached to this main lens system, it is possible to obtain good characteristics with respect to the original performance even when mounted on other lens systems. I can do it.
各数値実施例において、ｉは物体側から数えた順序を示す。ｒｉは第ｉ番目の光学面の曲率半径、ｄｉは第ｉ面と第（ｉ＋１）面との間の軸上間隔、ｎｄｉとνｄｉはそれぞれｄ線に対する第ｉ番目と第（ｉ＋１）面との間の媒質の屈折率、アッべ数を示す。Redはエクステンダーの倍率を示す。また、ｆは焦点距離、ＦｎｏはＦナンバー、ωは半画角であり、リアアタッチメントレンズの数値実施例においては、全て主レンズ系に装着した状態での値を示す。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。 In each numerical example, i indicates the order counted from the object side. ri is the radius of curvature of the i-th optical surface, di is the axial distance between the i-th surface and the (i + 1) -th surface, and ndi and νdi are the i-th and (i + 1) -th surfaces with respect to the d-line, respectively. The refractive index and Abbe number of the medium in between are shown. Red indicates the magnification of the extender. Further, f is a focal length, Fno is an F number, and ω is a half angle of view, and in the numerical examples of the rear attachment lens, all indicate values in a state where they are attached to the main lens system. Table 1 shows the relationship between the above-described conditional expressions and numerical values in the numerical examples.
(数値実施例）
（主レンズ系数値例）
i ri di ndi νdi θgF X
1 ∞ 5.00 1.51633 64.1 0.5352 -0.0007
2 ∞ 1.00
3 130.154 16.57 1.49700 81.5 0.5375 0.0309
4 -352.589 14.11
5 96.004 11.02 1.49700 81.5 0.5375 0.0309
6 793.095 4.07
7 -311.697 4.00 1.78590 44.2 0.5631 -0.0064
8 127.604 0.15
9 79.467 13.88 1.43387 95.1 0.5373 0.0534
10 -483.755 0.17
11 51.083 5.90 1.48749 70.2 0.5300 0.0043
12 40.134 26.71
13 1686.885 4.60 1.80518 25.4 0.6161 0.0150
14 -107.660 2.20 1.83481 42.7 0.5636 -0.0083
15 94.265 40.40
16 (絞り） 8.51
17 79.490 1.80 1.84666 23.8 0.6205 0.0167
18 35.239 7.20 1.72000 50.2 0.5535 -0.0058
19 -238.114 0.95
20 129.720 4.25 1.84666 23.8 0.6205 0.0167
21 -97.425 1.65 1.60311 60.6 0.5414 -0.0004
22 36.658 5.52
23 -76.051 1.60 1.77250 49.6 0.5521 -0.0083
24 66.247 2.82
25 78.646 9.30 1.72000 50.2 0.5535 -0.0058
26 -39.586 1.80 1.83400 37.2 0.5775 -0.0038
27 -155.699 4.00
28 81.751 5.50 1.69680 55.5 0.5433 -0.0071
29 ∞ 8.00
30 ∞ 2 1.51633 64.14 0.5352 -0.0007
※但し、X＝θgF-(0.6438-0.001682×νd)
主レンズ系の各種データ
ｆ 293.58
Fno 2.91
画角ω 4.22
像高Y 21.64
レンズ全長 274.02
バックフォーカス 59.35
(Numerical example)
(Example of main lens system values)
i ri di ndi νdi θgF X
1 ∞ 5.00 1.51633 64.1 0.5352 -0.0007
2 ∞ 1.00
3 130.154 16.57 1.49700 81.5 0.5375 0.0309
4 -352.589 14.11
5 96.004 11.02 1.49700 81.5 0.5375 0.0309
6 793.095 4.07
7 -311.697 4.00 1.78590 44.2 0.5631 -0.0064
8 127.604 0.15
9 79.467 13.88 1.43387 95.1 0.5373 0.0534
10 -483.755 0.17
11 51.083 5.90 1.48749 70.2 0.5300 0.0043
12 40.134 26.71
13 1686.885 4.60 1.80518 25.4 0.6161 0.0150
14 -107.660 2.20 1.83481 42.7 0.5636 -0.0083
15 94.265 40.40
16 (Aperture) 8.51
17 79.490 1.80 1.84666 23.8 0.6205 0.0167
18 35.239 7.20 1.72000 50.2 0.5535 -0.0058
19 -238.114 0.95
20 129.720 4.25 1.84666 23.8 0.6205 0.0167
21 -97.425 1.65 1.60311 60.6 0.5414 -0.0004
22 36.658 5.52
23 -76.051 1.60 1.77250 49.6 0.5521 -0.0083
24 66.247 2.82
25 78.646 9.30 1.72000 50.2 0.5535 -0.0058
26 -39.586 1.80 1.83400 37.2 0.5775 -0.0038
27 -155.699 4.00
28 81.751 5.50 1.69680 55.5 0.5433 -0.0071
29 ∞ 8.00
30 ∞ 2 1.51633 64.14 0.5352 -0.0007
* However, X = θgF- (0.6438-0.001682 × νd)
Various data of main lens system
f 293.58
Fno 2.91
Angle of view ω 4.22
Statue height Y 21.64
Total lens length 274.02
Back focus 59.35
（数値実施例1）
i ri di ndi νdi θgF X
1 ∞ 10.35
2 85.911 1.20 1.83481 42.7 0.5636 -0.0083
3 19.084 7.80 1.59551 39.2 0.5804 0.0026
4 -62.129 4.42
5 -94.475 1.20 1.77250 49.6 0.5521 -0.0083
6 16.798 11.20 1.65412 39.7 0.5737 -0.0033
7 -21.079 1.20 1.77250 49.6 0.5521 -0.0083
8 56.504 2.18
9 48.089 4.36 1.69895 30.1 0.6029 0.0098
10 -123.608 1.70
11 -39.122 1.20 1.92286 18.9 0.6495 0.0375
12 -1369.218 2.29
13 -187.967 6.57 1.65412 39.7 0.5737 -0.0033
14 -24.270 0.15
15 -85.052 1.50 1.77250 49.6 0.5521 -0.0083
16 -1401.904
※但し、X＝θgF-(0.6438-0.001682×νd)
数値実施例1の各種データ（主レンズ装着時）
Red 2.00
ｆ 586.01
Fno 5.87
画角ω 2.11
像高Y 21.64
レンズ全長 329.31
バックフォーカス 57.31
光学全長L 46.97
(Numerical example 1)
i ri di ndi νdi θgF X
1 ∞ 10.35
2 85.911 1.20 1.83481 42.7 0.5636 -0.0083
3 19.084 7.80 1.59551 39.2 0.5804 0.0026
4 -62.129 4.42
5 -94.475 1.20 1.77250 49.6 0.5521 -0.0083
6 16.798 11.20 1.65412 39.7 0.5737 -0.0033
7 -21.079 1.20 1.77250 49.6 0.5521 -0.0083
8 56.504 2.18
9 48.089 4.36 1.69895 30.1 0.6029 0.0098
10 -123.608 1.70
11 -39.122 1.20 1.92286 18.9 0.6495 0.0375
12 -1369.218 2.29
13 -187.967 6.57 1.65412 39.7 0.5737 -0.0033
14 -24.270 0.15
15 -85.052 1.50 1.77250 49.6 0.5521 -0.0083
16 -1401.904
* However, X = θgF- (0.6438-0.001682 × νd)
Various data of Numerical Example 1 (with main lens attached)
Red 2.00
f 586.01
Fno 5.87
Angle of view ω 2.11
Statue height Y 21.64
Total length 329.31
Back focus 57.31
Optical total length L 46.97
（数値実施例2）
i ri di ndi νdi θgF X
1 ∞ 10.35
2 136.414 1.20 1.83481 42.7 0.5636 -0.0083
3 22.175 7.36 1.59551 39.2 0.5804 0.0026
4 -68.331 9.43
5 -58.764 1.20 1.77250 49.6 0.5521 -0.0083
6 18.051 11.19 1.62588 35.7 0.5893 0.0055
7 -20.915 1.20 1.77250 49.6 0.5521 -0.0083
8 71.344 0.58
9 51.044 7.75 1.74950 35.3 0.5818 -0.0026
10 -27.171 1.20 1.80810 22.8 0.6307 0.0251
11 90.127 1.42
12 150.040 8.06 1.65412 39.7 0.5737 -0.0033
13 -27.823 0.15
14 -71.798 1.50 1.77250 49.6 0.5521 -0.0083
15 1016.662
※但し、X＝θgF-(0.6438-0.001682×νd)
数値実施例2の各種データ（主レンズ装着時）
Red 2.00
ｆ 586.02
Fno 5.87
画角ω 2.11
像高Y 21.64
レンズ全長 330.02
バックフォーカス 52.75
光学全長L 52.24
(Numerical example 2)
i ri di ndi νdi θgF X
1 ∞ 10.35
2 136.414 1.20 1.83481 42.7 0.5636 -0.0083
3 22.175 7.36 1.59551 39.2 0.5804 0.0026
4 -68.331 9.43
5 -58.764 1.20 1.77250 49.6 0.5521 -0.0083
6 18.051 11.19 1.62588 35.7 0.5893 0.0055
7 -20.915 1.20 1.77250 49.6 0.5521 -0.0083
8 71.344 0.58
9 51.044 7.75 1.74950 35.3 0.5818 -0.0026
10 -27.171 1.20 1.80810 22.8 0.6307 0.0251
11 90.127 1.42
12 150.040 8.06 1.65412 39.7 0.5737 -0.0033
13 -27.823 0.15
14 -71.798 1.50 1.77250 49.6 0.5521 -0.0083
15 1016.662
* However, X = θgF- (0.6438-0.001682 × νd)
Various data of Numerical Example 2 (with main lens attached)
Red 2.00
f 586.02
Fno 5.87
Angle of view ω 2.11
Statue height Y 21.64
Total lens length 330.02
Back focus 52.75
Optical total length L 52.24
（数値実施例3）
i ri di ndi νdi θgF X
1 10.35
2 92.808 1.50 1.80400 46.6 0.5572 -0.0083
3 22.273 8.08 1.59551 39.2 0.5804 0.0026
4 -80.529 6.85
5 -86.414 1.50 1.77250 49.6 0.5521 -0.0083
6 80.626 4.95
7 -30.609 1.50 1.83481 42.7 0.5636 -0.0083
8 -122.847 0.15
9 92.075 1.60 1.92286 18.9 0.6495 0.0375
10 53.083 9.97 1.65412 39.7 0.5737 -0.0033
11 -36.550
※但し、X＝θgF-(0.6438-0.001682×νd)
数値実施例3の各種データ（主レンズ装着時）
Red 1.39
ｆ 408.00
Fno 4.05
画角ω 3.04
像高Y 21.64
レンズ全長 300.55
バックフォーカス 39.43
光学全長L 36.1
(Numerical example 3)
i ri di ndi νdi θgF X
1 10.35
2 92.808 1.50 1.80400 46.6 0.5572 -0.0083
3 22.273 8.08 1.59551 39.2 0.5804 0.0026
4 -80.529 6.85
5 -86.414 1.50 1.77250 49.6 0.5521 -0.0083
6 80.626 4.95
7 -30.609 1.50 1.83481 42.7 0.5636 -0.0083
8 -122.847 0.15
9 92.075 1.60 1.92286 18.9 0.6495 0.0375
10 53.083 9.97 1.65412 39.7 0.5737 -0.0033
11 -36.550
* However, X = θgF- (0.6438-0.001682 × νd)
Various data of Numerical Example 3 (with main lens attached)
Red 1.39
f 408.00
Fno 4.05
Angle of view ω 3.04
Statue height Y 21.64
Total lens length 300.55
Back focus 39.43
Optical total length L 36.1
次に本発明における各数値実施例のリアアタッチメントレンズの構成について説明する。数値実施例１のリアアタッチメントレンズＬＡは、物体側より像側へ順に、負レンズ、正レンズGP1の順で接合した接合レンズＬ１、負レンズ、正レンズ、負レンズの順で接合した接合レンズＬ２から構成されている。さらに、正レンズＬ３、負レンズ(Gn1)Ｌ４、正レンズ(Gp2)Ｌ５、負レンズＬ６から構成されている。 Next, the configuration of the rear attachment lens of each numerical example in the present invention will be described. The rear attachment lens LA of Numerical Example 1 includes a cemented lens L1 that is cemented in order of a negative lens and a positive lens GP1, and a cemented lens L2 that is cemented in the order of a negative lens, a positive lens, and a negative lens in order from the object side to the image side. It is composed of Further, it is composed of a positive lens L3, a negative lens (Gn1) L4, a positive lens (Gp2) L5, and a negative lens L6.
数値実施例２のリアアタッチメントレンズＬＡは、物体側より像側へ順に、負レンズ、正レンズGP1の順で接合した接合レンズＬ１、負レンズ、正レンズ、負レンズの順で接合した接合レンズＬ２から構成されている。さらに正レンズGp2、負レンズGn1の順で接合した接合レンズＬ３、正レンズ(Gp2)Ｌ４、負レンズＬ５から構成されている。 The rear attachment lens LA of Numerical Example 2 is a cemented lens L2 that is cemented in order of a negative lens and a positive lens GP1, and a cemented lens L2 that is cemented in the order of a negative lens, a positive lens, and a negative lens in this order from the object side to the image side. It is composed of Further, the lens includes a cemented lens L3, a positive lens (Gp2) L4, and a negative lens L5 that are cemented in order of a positive lens Gp2 and a negative lens Gn1.
数値実施例３のリアアタッチメントレンズＬＡは物体側より像側へ順に負レンズ、正レンズGP1の順で接合した接合レンズＬ１、負レンズＬ２、負レンズＬ３、負レンズGn1、正レンズGp2の順で接合した接合レンズＬ４から構成されている。 In the rear attachment lens LA of Numerical Example 3, the cemented lens L1, the negative lens L2, the negative lens L3, the negative lens Gn1, and the positive lens Gp2 are joined in this order from the object side to the image side in the order of the negative lens and the positive lens GP1. It is comprised from the cemented cemented lens L4.
数値実施例１の負レンズ(Gn1)Ｌ４、数値実施例２の接合レンズＬ３の負レンズGn1、数値実施例３の接合レンズＬ４の負レンズGn1は、それぞれ条件式（1）、（2）を満たしている。かつ軸上光線の入射高ｈが低く、軸外主光線の入射高ｈ-が高い位置に配置されている。それにより、軸上色収差を劣化させることなく、Ｃ線、Ｆ線、ｇ線の倍率色収差を良好に補正している。 The negative lens (Gn1) L4 of Numerical Example 1, the negative lens Gn1 of the cemented lens L3 of Numerical Example 2, and the negative lens Gn1 of the cemented lens L4 of Numerical Example 3 are conditional expressions (1) and (2), respectively. Satisfies. In addition, the incident height h of the on-axis light beam is low and the incident height h- of the off-axis principal ray is high. Thereby, the lateral chromatic aberration of the C-line, F-line, and g-line is corrected well without deteriorating the longitudinal chromatic aberration.
また、数値実施例１の接合レンズＬ１の正レンズGP1、数値実施例２の接合レンズＬ１の正レンズGP1、数値実施例３の接合レンズＬ１の正レンズGP1は、それぞれ条件式（3）、（4）を満たしている。かつ軸上光線の入射高ｈが高く、軸外主光線の入射高ｈ-が低い位置に配置されている。それにより、前記条件式（1）、（2）を満たす負レンズで、幾分劣化した軸上色収差を、倍率色収差を劣化することなく補正している。 The positive lens GP1 of the cemented lens L1 of Numerical Example 1, the positive lens GP1 of the cemented lens L1 of Numerical Example 2, and the positive lens GP1 of the cemented lens L1 of Numerical Example 3 are conditional expressions (3) and (3), respectively. 4) is met. In addition, the incident height h of the on-axis light beam is high and the incident height h- of the off-axis principal ray is low. Thereby, with the negative lens satisfying the conditional expressions (1) and (2), the slightly deteriorated axial chromatic aberration is corrected without deteriorating the lateral chromatic aberration.
また、数値実施例１の正レンズ(Gp2)Ｌ５、数値実施例２の接合レンズＬ３の正レンズGp2及び正レンズ(Gp2)Ｌ４、数値実施例３の接合レンズＬ４の正レンズGp2は、各々条件式（5）、（6）を満たしている。かつ軸上光線の入射高ｈが低く、軸外主光線の入射高ｈ-が高い位置に配置されている。それにより、軸上色収差を劣化させることなく、ｇ線の倍率色収差を良好に補正している。このとき、各数値実施例で使用される、条件式（1）、（2）を満たす負レンズの材料には、ＮｐＯ2を主原料とする材料を使用している。 Further, the positive lens (Gp2) L5 in Numerical Example 1, the positive lens Gp2 and the positive lens (Gp2) L4 of the cemented lens L3 in Numerical Example 2, and the positive lens Gp2 of the cemented lens L4 in Numerical Example 3 are respectively Expressions (5) and (6) are satisfied. In addition, the incident height h of the on-axis light beam is low and the incident height h- of the off-axis principal ray is high. Thereby, the lateral chromatic aberration of the g-line is corrected well without deteriorating the longitudinal chromatic aberration. At this time, as a negative lens material satisfying the conditional expressions (1) and (2) used in each numerical example, a material mainly composed of NpO 2 is used.
また、各数値実施例で使用される、条件式（5）、（6）を満たす正レンズの材料には、Ｎｂ２Ｏ３を主原料とする材料を使用している。一般にＮｐＯ2を主原料とする材料は、青側の透過光の透過率が低く、中心肉厚が薄い負レンズとしても、全系での青側の透過光の透過率が若干劣化する。 Also used in the numerical examples, the conditional expression (5), the material of the positive lens that satisfies (6), using materials of the Nb 2 O 3 as a main material. In general, a material containing NpO 2 as a main raw material has a low transmittance of transmitted light on the blue side, and the transmittance of transmitted light on the blue side in the entire system is slightly deteriorated even in a negative lens having a thin center thickness.
そこで本発明では、その青側の透過光の透過率の劣化分を補償するべく、中心肉厚が厚く、青側の透過光の透過率が低い高分散材料よりなる正レンズに着目した。通常、高分散性の材料よりなる正レンズとして良く使用されるＴｉＯ2を主原料とする材料ではなく、青側の透過光の透過率が若干良いＮｂ２Ｏ３を主原料とする材料を用いることで、全光学系での透過光の色味変化を抑えている。 Therefore, in the present invention, in order to compensate for the deterioration of the transmittance of the blue side transmitted light, attention is paid to a positive lens made of a high dispersion material having a thick central wall and a low transmittance of the blue side transmitted light. Usually, a material mainly made of Nb 2 O 3 with slightly good transmittance of transmitted light on the blue side is used instead of a material mainly made of TiO 2 that is often used as a positive lens made of a highly dispersible material. This suppresses a change in the color of transmitted light in the entire optical system.
次に、本発明のリアアタッチメントレンズを主レンズ系の像側に装着し、撮影光学系として用いた一眼レフカメラ（撮像装置）の実施例を図９を用いて説明する。同図において、１０は実施例１、２、３の撮影光学系１を有する撮影レンズである。撮影光学系１は保持部材である鏡筒２に保持されている。２０はカメラ本体であり、撮影レンズ１０からの光束を上方に反射するクイックリターンミラー３、撮影レンズ１０の像形成位置に配置された焦点板４を有している。更に、焦点板４に形成された逆像を正立像に変換するペンタダハプリズム５、その正立像を拡大結像するための接眼レンズ６等を有している。７は感光面であり、受光手段(記録手段）としてのＣＣＤセンサやＣＭＯＳセンサ等の固体撮像素子（光電変換素子）や銀塩フィルムが配置される。撮影時にはクイックリターンミラー３が光路から退避して、感光面７上に撮影レンズ１０によって像が形成される。 Next, an embodiment of a single-lens reflex camera (imaging device) in which the rear attachment lens of the present invention is mounted on the image side of the main lens system and used as a photographing optical system will be described with reference to FIG. In the figure, reference numeral 10 denotes a photographing lens having the photographing optical system 1 of the first, second, and third embodiments. The photographing optical system 1 is held by a lens barrel 2 that is a holding member. Reference numeral 20 denotes a camera body, which includes a quick return mirror 3 that reflects the light beam from the photographing lens 10 upward and a focusing screen 4 that is disposed at an image forming position of the photographing lens 10. Further, it has a penta roof prism 5 for converting an inverted image formed on the focusing screen 4 into an erect image, an eyepiece 6 for enlarging the erect image, and the like. Reference numeral 7 denotes a photosensitive surface, on which a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor or a silver salt film is disposed as a light receiving means (recording means). At the time of photographing, the quick return mirror 3 is retracted from the optical path, and an image is formed on the photosensitive surface 7 by the photographing lens 10.
以上、本発明の好ましい光学系の実施例について説明したが、本発明はこれらの実施例に限定されないことは言うまでもなく、その要旨の範囲内で種々の変形及び変更が可能である。 As mentioned above, although the Example of the preferable optical system of this invention was described, it cannot be overemphasized that this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary.
ＬＭ 主レンズ系、ＬＡ リアアタッチメントレンズ、Ｓ 開口絞り、ＩＰ 像面、ｄ ｄ線、ｇ ｇ線、Ｃ Ｃ線、Ｆ Ｆ線 LM main lens system, LA rear attachment lens, S aperture stop, IP image plane, dd line, g g line, CC line, FF line
Claims (5)
10＜νdn1＜23
0.020＜θgFn1−0.6438＋0.001682×νdn1＜0.100
なる条件を満足していることを特徴とするリアアタッチメントレンズ。 In a rear attachment lens that is detachably attached to the image side of the main lens system and changes the focal length in a longer direction than the focal length of the main lens system alone, the rear attachment lens is the most from the lens surface on the most object side. When the distance to the image-side lens surface is L, the rear attachment lens has a negative lens Gn1 when the distance from the most object-side lens surface is 0.5 L to 1.0 L, and The negative lens Gn1 has a Abbe number of the material with respect to the d-line as νdn1, and a partial dispersion ratio with respect to the g-line and F-line as θgFn1
10 <νdn1 <23
0.020 <θgFn1−0.6438 + 0.001682 × νdn1 <0.100
A rear attachment lens characterized by satisfying the following conditions.
1.90＜Ndp1＋0.0125νdp1＜2.24
0.001＜θgFp1−0.6438＋0.001682×νdp1＜0.020
なる条件を満足していることを特徴とする請求項１に記載のリアアタッチメントレンズ。 The rear attachment lens has a positive lens Gp1 within a distance from the most object-side lens surface of 0 to 0.5 L, and the positive lens Gp1 has a refractive index and an Abbe number for the d-line of the material, respectively. When the partial dispersion ratio for Ndp1, νdp1, g-line and F-line is θgFp1,
1.90 <Ndp1 + 0.0125νdp1 <2.24
0.001 <θgFp1−0.6438 + 0.001682 × νdp1 <0.020
The rear attachment lens according to claim 1, wherein the following condition is satisfied.
1.90＜Ndp2＋0.0125νdp2＜2.24
−0.010＜θgFp2−0.6438＋0.001682×νdp2＜0.003
なる条件を満足していることを特徴とする請求項１又は２に記載のリアアタッチメントレンズ。 The rear attachment lens has a positive lens Gp2 within a distance of 0.5L to 1.0L from the lens surface closest to the object side. The positive lens Gp2 has a refractive index and an Abbe number with respect to the d-line of the material. Is Ndp2, νdp2, and the partial dispersion ratio for g-line and F-line is θgFp2, respectively.
1.90 <Ndp2 + 0.0125νdp2 <2.24
−0.010 <θgFp2−0.6438 + 0.001682 × νdp2 <0.003
The rear attachment lens according to claim 1, wherein the following condition is satisfied.
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
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| JP2009232225A JP5393385B2 (en) | 2009-10-06 | 2009-10-06 | Rear attachment lens and photographing optical system having the same |
| EP10176325.8A EP2312341B1 (en) | 2009-10-06 | 2010-09-13 | Rear attachment lens and imaging optical system including the same |
| EP12164784.6A EP2492715B1 (en) | 2009-10-06 | 2010-09-13 | Rear attachment lens, imaging optical system, and image pickup apparatus |
| US12/885,142 US8223436B2 (en) | 2009-10-06 | 2010-09-17 | Rear attachment lens, imaging optical system and image pickup apparatus |
| CN201210123956.1A CN102645731B (en) | 2009-10-06 | 2010-09-29 | Rear attachment lens and imaging optical system including the same |
| CN2010105095090A CN102033303B (en) | 2009-10-06 | 2010-09-29 | Rear attachment lens and imaging optical system and image pickup apparatus |
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| JP2011081111A true JP2011081111A (en) | 2011-04-21 |
| JP2011081111A5 JP2011081111A5 (en) | 2012-11-08 |
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| JP2016045314A (en) * | 2014-08-21 | 2016-04-04 | 株式会社シグマ | Rear conversion lens |
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| JP2018025676A (en) * | 2016-08-10 | 2018-02-15 | キヤノン株式会社 | Rear converter optical system and imaging apparatus having the same |
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| US10838166B2 (en) | 2017-05-31 | 2020-11-17 | Fujifilm Corporation | Rear attachment lens and imaging apparatus |
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| US9075291B2 (en) | 2012-05-11 | 2015-07-07 | Olympus Imaging Corp. | Teleconverter, and imaging system comprising the same |
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| US10838166B2 (en) | 2017-05-31 | 2020-11-17 | Fujifilm Corporation | Rear attachment lens and imaging apparatus |
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