JP2007086308A - Imaging optical system and interchangeable lens device having the same - Google Patents
Imaging optical system and interchangeable lens device having the same Download PDFInfo
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Abstract
Description
本発明は、カメラ（特にレンズ交換式カメラ）等に用いられる結像光学系及びそれを備えた交換レンズ装置に関するものである。
特に、ＣＣＤ（固体撮像素子）やＣ−ＭＯＳ等の電子撮像素子を備えたカメラに用いられる結像光学系、特にレンズ交換式のデジタルカメラの交換レンズに適した結像光学系及びそれを備えた交換レンズ装置に関するものである。
The present invention relates to an imaging optical system used for a camera (particularly, an interchangeable lens camera) and the like, and an interchangeable lens apparatus including the same.
In particular, an imaging optical system used for a camera having an electronic imaging device such as a CCD (solid-state imaging device) or C-MOS, particularly an imaging optical system suitable for an interchangeable lens of an interchangeable lens digital camera, and the same The present invention relates to an interchangeable lens device.
近年、銀塩フィルムを使用する一眼レフカメラに代わって、ＣＣＤ、Ｃ−ＭＯＳ等、光学像を電気信号に変換する電子撮像素子を用いたデジタル一眼レフカメラが注目されている。
これらデジタル一眼レフカメラは、フィルム用カメラでは一般的な１３５フォーマットの受光面積よりも小さい受光面積を持つ電子撮像素子を用いたものが主流である。
このような、受光面積のサイズの小型化に合わせて、結像光学系自体も小型化が行なわれている。
In recent years, a digital single-lens reflex camera using an electronic image sensor that converts an optical image into an electric signal, such as a CCD or a C-MOS, is drawing attention in place of a single-lens reflex camera using a silver salt film.
Most of these digital single-lens reflex cameras use an electronic image pickup device having a light receiving area smaller than the light receiving area of the 135 format that is generally used for film cameras.
As the light receiving area is reduced in size, the imaging optical system itself is also reduced in size.
一方、１３５フォーマット専用の標準画角を持つ結像光学系として、ガウスタイプと呼ばれる結像光学系が知られている。このガウスタイプと呼ばれる結像光学系は、明るさ絞りに対して概略対称系に配されたレンズ構成となっており、その対称性のよさから、優れた収差補正能力を持つことが知られている。
しかしながら、これらのガウスタイプとよばれるタイプの結像光学系は、主として１３５フォーマットのフィルム用に設計されたものが多い。そのため、前述のように受光面積が小さいタイプのカメラに用いようとすると、十分な画角が得られなくなってくる。
受光面積のサイズに併せて結像光学系を小さくしようとすると、こんどはバックフォーカスが短くなってくる。バックフォーカスが短くなると、デジタル一眼レフレックスカメラの場合、クイックリターンミラーなどの光路分割部材やフィルター類を配するスペースが小さくなり、光学レイアウト上不利となってくる。
一方、バックフォーカスの確保と画角の維持のためにレトロフォーカスタイプのレンズ構成とすると、結像光学系の入射面の径が大きくなり易い。
On the other hand, an imaging optical system called a Gaussian type is known as an imaging optical system having a standard angle of view dedicated to the 135 format. This Gauss type imaging optical system has a lens configuration arranged in a roughly symmetrical system with respect to the aperture stop, and is known to have excellent aberration correction capability due to its symmetry. Yes.
However, many of these Gaussian type imaging optical systems are designed mainly for 135 format film. Therefore, if the camera is used for a camera with a small light receiving area as described above, a sufficient angle of view cannot be obtained.
If the imaging optical system is made smaller in accordance with the size of the light receiving area, the back focus will be shortened. When the back focus is shortened, in the case of a digital single-lens reflex camera, a space for arranging optical path dividing members such as a quick return mirror and filters is reduced, which is disadvantageous in terms of optical layout.
On the other hand, if a retrofocus type lens configuration is used to ensure back focus and maintain the angle of view, the diameter of the entrance surface of the imaging optical system tends to increase.
そのため、ガウスタイプの対称性をできるだけ維持したまま長いバックフォーカスを得た従来技術として、例えば、次の特許文献１、２に記載のものが提案されている。
これらの先行技術は、一般的なガウスタイプのレンズを基に、絞り直前の負レンズ成分とその物体側の正レンズ成分の配置を入れ替えることで、バックフォーカスを長くしたものである。
In these prior arts, the back focus is lengthened by switching the arrangement of the negative lens component immediately before the stop and the positive lens component on the object side based on a general Gauss type lens.
しかしながら、上述の先行技術文献のものであっても、昨今のデジタル一眼レフに求められるバックフォーカスを考慮すると、焦点距離に対するバックフォーカスの長さの確保が十分とはいい難い。 However, even with the above-described prior art documents, it is difficult to ensure the length of the back focus with respect to the focal length in consideration of the back focus required for recent digital single lens reflex cameras.
本発明は、上記問題点に鑑みてなされたものであり、バックフォーカスの長さを確保し、光学性能も良好に確保することのできる結像光学系及びそれを備えた交換レンズ装置を提供することを目的としている。 The present invention has been made in view of the above problems, and provides an imaging optical system capable of ensuring the length of a back focus and ensuring good optical performance, and an interchangeable lens apparatus including the same. The purpose is that.
上記目的を達成するため、本第１の発明による結像光学系は、物体側から順に、正の屈折力を持つ前群と、明るさ絞りと、正の屈折力を持つ後群とからなり、前記後群が、物体側から順に、負レンズ成分と、第１の正レンズ成分と、第２の正レンズ成分を有し、次の条件式(1)，(2)を満足することを特徴としている。
−４．０＜ｆＲ１２Ａ／ｆ＜−０．５ ・・・(1)
０．７＜ｆｂ／ｆ＜１．５ ・・・(2)
ただし、ｆは前記結像光学系全系の焦点距離、ｆＲ１２Ａは前記後群の負レンズ成分と該負レンズ成分の像側に位置する正レンズ成分とに挟まれる空気レンズの焦点距離、ｆｂは前記後群における最も像側のレンズの射出面から焦点までの光軸上での空気換算距離、である。
また、ここでのレンズ成分は、いずれも、光軸上において、各レンズ成分における最も物体側の面と最も像側の面のみが空気と接し、それらの面の間が空気と接しない、単レンズ又は接合レンズを意味する。
In order to achieve the above object, the imaging optical system according to the first invention comprises, in order from the object side, a front group having a positive refractive power, an aperture stop, and a rear group having a positive refractive power. The rear group has, in order from the object side, a negative lens component, a first positive lens component, and a second positive lens component, and satisfies the following conditional expressions (1) and (2): It is a feature.
-4.0 <fR12A / f <-0.5 (1)
0.7 <fb / f <1.5 (2)
Where f is the focal length of the entire imaging optical system, fR12A is the focal length of the air lens sandwiched between the negative lens component of the rear group and the positive lens component located on the image side of the negative lens component, and fb is This is the air equivalent distance on the optical axis from the exit surface to the focal point of the most image side lens in the rear group.
In addition, all the lens components here are on the optical axis, only the most object-side surface and the most image-side surface of each lens component are in contact with air, and those surfaces are not in contact with air. It means a lens or a cemented lens.
また、本第１の発明の結像光学系においては、前記前群が、前記明るさ絞り側に向けた凹面を有する、該前群における最も像側のレンズ成分と、該前群における最も像側のレンズ成分よりも物体側に配置された正レンズ成分を有し、前記後群の前記負レンズ成分が、前記明るさ絞り側に凹面を向けているのが好ましい。 In the imaging optical system according to the first aspect of the invention, the front group has a concave surface directed toward the brightness stop side, and the most image side lens component in the front group and the most image in the front group. It is preferable that the positive lens component is disposed closer to the object side than the lens component on the side, and the negative lens component of the rear group has a concave surface facing the aperture stop side.
また、本第２の発明の結像光学系は、物体側から順に、正の屈折力を持つ前群と、明るさ絞りと、正の屈折力を持つ後群とからなり、前記前群が、像側から順に、前記明るさ絞り側に向けた凹面を有する正メニスカスレンズ成分と、負レンズ成分と、正レンズ成分を有し、前記後群が、物体側から順に、前記明るさ絞り側に向けた凹面を有する負レンズ成分と、第１の正レンズ成分と、第２の正レンズ成分を有し、次の条件式(1)を満足することを特徴としている。
−４．０＜ｆＲ１２Ａ／ｆ＜−０．５ ・・・(1)
ただし、ｆは前記結像光学系全系の焦点距離、ｆＲ１２Ａは前記後群の負レンズ成分と該負レンズ成分の像側に位置する正レンズ成分とに挟まれる空気レンズの焦点距離、である。
また、ここでのレンズ成分は、いずれも、光軸上において、各レンズ成分における最も物体側の面と最も像側の面のみが空気と接し、それらの面の間が空気と接しない、単レンズ又は接合レンズを意味する。
The imaging optical system according to the second aspect of the present invention includes, in order from the object side, a front group having a positive refractive power, an aperture stop, and a rear group having a positive refractive power. A positive meniscus lens component having a concave surface directed toward the aperture stop side in order from the image side, a negative lens component, and a positive lens component, and the rear group in order from the object side to the aperture stop side It has a negative lens component having a concave surface facing the first, a first positive lens component, and a second positive lens component, and satisfies the following conditional expression (1).
-4.0 <fR12A / f <-0.5 (1)
Where f is the focal length of the entire imaging optical system, and fR12A is the focal length of the air lens sandwiched between the negative lens component of the rear group and the positive lens component located on the image side of the negative lens component. .
In addition, all the lens components here are on the optical axis, only the most object-side surface and the most image-side surface of each lens component are in contact with air, and those surfaces are not in contact with air. It means a lens or a cemented lens.
本発明によれば、バックフォーカスを長くしても、光学性能も良好に確保することのできる結像光学系及びそれを備えた交換レンズ装置が得られる。さらには、レンズの外径の大型化を抑え易い結像光学系及びそれを備えた交換レンズ装置が得られる。 According to the present invention, it is possible to obtain an imaging optical system and an interchangeable lens apparatus including the imaging optical system that can ensure good optical performance even when the back focus is lengthened. Furthermore, an imaging optical system that easily suppresses an increase in the outer diameter of the lens and an interchangeable lens device including the same can be obtained.
実施例の説明に先立ち、本発明のより具体的な作用効果について説明する。
本第１の発明の結像光学系は、物体側から順に、正の屈折力を持つ前群と、明るさ絞りと、正の屈折力を持つ後群とからなり、前記後群が、物体側から順に、負レンズ成分と、第１の正レンズ成分と、第２の正レンズ成分を有し、次の条件式(1)，(2)を満足する。
−４．０＜ｆＲ１２Ａ／ｆ＜−０．５ ・・・(1)
０．７＜ｆｂ／ｆ＜１．５ ・・・(2)
ただし、ｆは前記結像光学系全系の焦点距離、ｆＲ１２Ａは前記後群の負レンズ成分と該負レンズ成分の像側に位置する正レンズ成分とに挟まれる空気レンズの焦点距離、ｆｂは前記後群における最も像側のレンズの射出面から焦点までの光軸上での空気換算距離、である。
また、ここでのレンズ成分は、いずれも、光軸上において、各レンズ成分における最も物体側の面と最も像側の面のみが空気と接し、それらの面の間が空気と接しない、単レンズ又は接合レンズを意味する。
Prior to the description of the embodiments, more specific operational effects of the present invention will be described.
The imaging optical system according to the first aspect of the present invention includes, in order from the object side, a front group having a positive refractive power, an aperture stop, and a rear group having a positive refractive power. In order from the side, there are a negative lens component, a first positive lens component, and a second positive lens component, and the following conditional expressions (1) and (2) are satisfied.
-4.0 <fR12A / f <-0.5 (1)
0.7 <fb / f <1.5 (2)
Where f is the focal length of the entire imaging optical system, fR12A is the focal length of the air lens sandwiched between the negative lens component of the rear group and the positive lens component located on the image side of the negative lens component, and fb is This is the air equivalent distance on the optical axis from the exit surface to the focal point of the most image side lens in the rear group.
In addition, all the lens components here are on the optical axis, only the most object-side surface and the most image-side surface of each lens component are in contact with air, and those surfaces are not in contact with air. It means a lens or a cemented lens.
即ち、本第１の発明の結像光学系では、明るさ絞りを挟む前群と後群とで正の屈折力を分担している。このように、明るさ絞りに対して対称な屈折力の配置とすると、歪曲収差等の軸外収差の補正に有利となる。
ただし、このような明るさ絞りを挟む前群と後群とで正の屈折力を分担する光学構成において、バックフォーカスを長くしようとすると、前群の正の屈折力が弱くなり易い。
そこで、本第１の発明では、条件式(2)で規定するバックフォーカスを確保しても、収差を良好に補正するために、条件式(1)を満足するように構成している。
That is, in the imaging optical system according to the first aspect of the invention, the positive refractive power is shared by the front group and the rear group that sandwich the aperture stop. Thus, the arrangement of refractive power symmetrical to the aperture stop is advantageous for correcting off-axis aberrations such as distortion.
However, in an optical configuration in which the front group and rear group that share such an aperture stop share the positive refractive power, if the back focus is increased, the positive refractive power of the front group tends to be weakened.
Therefore, the first invention is configured to satisfy the conditional expression (1) in order to satisfactorily correct the aberration even when the back focus specified by the conditional expression (2) is secured.
条件式(1)は、結像光学系全系の焦点距離に対する、後群の負レンズ成分とそのレンズ成分の像側に位置する正レンズ成分とに挟まれる空気レンズの焦点距離を規定した式である。
この空気レンズの焦点距離ｆＲ１２Ａは負の値となるが、この負の屈折力を条件式(1)を満足するように、適度に強くすると、後群の物体側に負の屈折力を寄せることが可能となる。そして、この空気レンズの像側に複数の正レンズ成分を配置し、後群における正の屈折力をこの空気レンズの像側にて負担させている。このようにすると、前群、後群のパワーバランスを維持し易くなり、光学性能も良好に保ちつつ、バックフォーカスを長くすることが可能となる。
Conditional expression (1) defines the focal length of the air lens sandwiched between the negative lens component in the rear group and the positive lens component located on the image side of the lens component with respect to the focal length of the entire imaging optical system. It is.
Although the focal length fR12A of this air lens is a negative value, if this negative refractive power is moderately increased so as to satisfy the conditional expression (1), the negative refractive power is brought closer to the object side of the rear group. Is possible. A plurality of positive lens components are arranged on the image side of the air lens, and the positive refractive power in the rear group is borne on the image side of the air lens. In this way, it becomes easy to maintain the power balance of the front group and the rear group, and it becomes possible to lengthen the back focus while maintaining good optical performance.
条件式(1)の下限値を下回って空気レンズの負の屈折力が小さくなると、必要なバックフォーカスを確保するためには前群の正の屈折力が弱くなり易くなる。そのため、明るさ絞りの前後の屈折力の対称性を良好にすることが難しくなり、全体の収差バランスがとり難くなる。
一方、条件式(1)の上限値を上回って空気レンズの負屈折力が強くなると、後群の第１の正レンズ成分に入射する光束の発散性が強くなりすぎてしまう。そのため、後群に第１の正レンズ成分と第２の正レンズ成分というように複数の正レンズ成分を備えても、収差補正が難しくなり、特に、球面収差がアンダーになり易くなる。
When the negative refracting power of the air lens becomes smaller than the lower limit value of the conditional expression (1), the positive refracting power of the front group tends to be weak in order to secure the necessary back focus. For this reason, it becomes difficult to improve the symmetry of the refractive power before and after the aperture stop, making it difficult to balance the overall aberration.
On the other hand, when the negative refracting power of the air lens becomes stronger than the upper limit value of the conditional expression (1), the divergence of the light beam incident on the first positive lens component in the rear group becomes too strong. Therefore, even when a plurality of positive lens components such as the first positive lens component and the second positive lens component are provided in the rear group, it is difficult to correct aberrations, and in particular, spherical aberration tends to be under.
条件式(2)の下限値を下回ると、バックフォーカスが短くなってしまう。
一方、条件式(2)の上限値を上回ると、バックフォーカスが長くなりすぎてしまい、結像光学系の入射面から像面までの距離が長くなりすぎてしまい、小型化に不利となる。
If the lower limit of conditional expression (2) is not reached, the back focus will be shortened.
On the other hand, if the upper limit value of conditional expression (2) is exceeded, the back focus becomes too long, and the distance from the incident surface to the image surface of the imaging optical system becomes too long, which is disadvantageous for miniaturization.
なお、条件式(1)の下限値を−３．５とすると、より好ましい。
また、条件式(1)の上限値を−０．８、更には−１．０とすると、より好ましい。
また、条件式(2)の下限値を０．８、更には０．９５とすると、より好ましい。
また、条件式(2)の上限値を１．３、更には１．２とすると、より好ましい。
It is more preferable that the lower limit value of conditional expression (1) is −3.5.
Further, it is more preferable that the upper limit value of the conditional expression (1) is −0.8, and further −1.0.
Further, it is more preferable that the lower limit value of conditional expression (2) is 0.8, further 0.95.
Further, it is more preferable that the upper limit value of conditional expression (2) is 1.3, further 1.2.
また、本第１の発明の結像光学系においては、前記前群が、前記明るさ絞り側に向けた凹面を有する、該前群における最も像側のレンズ成分と、該前群における最も像側のレンズ成分よりも物体側に配置された正レンズ成分を有し、前記後群の前記負レンズ成分が、前記明るさ絞り側に凹面を向けるのが好ましい。 In the imaging optical system according to the first aspect of the invention, the front group has a concave surface directed toward the brightness stop side, and the most image side lens component in the front group and the most image in the front group. It is preferable that the positive lens component is disposed closer to the object side than the lens component on the side, and the negative lens component of the rear group has a concave surface facing the aperture stop side.
即ち、本第１の発明の結像光学系では、明るさ絞りを挟む前群と後群とで正の屈折力を分担することに加えて、明るさ絞りを挟む空気レンズが両凸形状となるようにして、この空気レンズに負の屈折力を与えるのが好ましい。このようにすれば、前群、後群中の正レンズ成分とも相まって、球面収差、ペッツバール和の補正が行い易くなる。また、明るさ絞りに対して対称性を維持し易く、軸外収差補正や、光学系の小径化にも有利となる。 That is, in the imaging optical system according to the first aspect of the invention, in addition to sharing the positive refractive power between the front group and the rear group that sandwich the brightness stop, the air lens that sandwiches the brightness stop has a biconvex shape. Thus, it is preferable to give a negative refractive power to the air lens. This facilitates correction of spherical aberration and Petzval sum in combination with the positive lens components in the front group and rear group. Further, it is easy to maintain symmetry with respect to the aperture stop, which is advantageous for off-axis aberration correction and for reducing the diameter of the optical system.
本第２の発明の結像光学系は、物体側から順に、正の屈折力を持つ前群と、明るさ絞りと、正の屈折力を持つ後群とからなり、前記前群が、像側から順に、前記明るさ絞り側に向けた凹面を有する正メニスカスレンズ成分と、負レンズ成分と、正レンズ成分を有し、前記後群が、物体側から順に、前記明るさ絞り側に向けた凹面を有する負レンズ成分と、第１の正レンズ成分と、第２の正レンズ成分を有し、次の条件式(1)を満足する。
−４．０＜ｆＲ１２Ａ／ｆ＜−０．５ ・・・(1)
ただし、ｆは前記結像光学系全系の焦点距離、ｆＲ１２Ａは前記後群の負レンズ成分と該負レンズ成分の像側に位置する正レンズ成分とに挟まれる空気レンズの焦点距離、である。
また、ここでのレンズ成分は、いずれも、光軸上において、各レンズ成分における最も物体側の面と最も像側の面のみが空気と接し、それらの面の間が空気と接しない、単レンズ又は接合レンズを意味する。
The imaging optical system according to the second aspect of the present invention comprises, in order from the object side, a front group having a positive refractive power, an aperture stop, and a rear group having a positive refractive power. In order from the side, the lens has a positive meniscus lens component having a concave surface facing the aperture stop side, a negative lens component, and a positive lens component, and the rear group is directed from the object side toward the aperture stop side. It has a negative lens component having a concave surface, a first positive lens component, and a second positive lens component, and satisfies the following conditional expression (1).
-4.0 <fR12A / f <-0.5 (1)
Where f is the focal length of the entire imaging optical system, and fR12A is the focal length of the air lens sandwiched between the negative lens component of the rear group and the positive lens component located on the image side of the negative lens component. .
In addition, all the lens components here are on the optical axis, only the most object-side surface and the most image-side surface of each lens component are in contact with air, and those surfaces are not in contact with air. It means a lens or a cemented lens.
本第２の発明の結合光学系では、上述の本第１の発明における条件式(2)に代えて、前群の構成要件をより具体的に特定している。
本第２の発明の結像光学系においても、明るさ絞りを挟む前群と後群とで正屈折力を分担している。加えて、明るさ絞りを挟む空気レンズが両凸形状となるようにして、この空気レンズに負の屈折力を与えている。このようにすれば、前群、後群中の正レンズ成分とも相まって、球面収差、ペッツバール和の補正が行い易くなる。また、明るさ絞りに対して対称性を維持し易く、軸外収差補正や、光学系の小径化にも有利となる。
In the coupling optical system according to the second invention, the constituent elements of the front group are more specifically specified in place of the conditional expression (2) in the first invention described above.
Also in the imaging optical system according to the second aspect of the invention, the positive refractive power is shared by the front group and the rear group that sandwich the aperture stop. In addition, a negative refractive power is given to the air lens so that the air lens sandwiching the aperture stop has a biconvex shape. This facilitates correction of spherical aberration and Petzval sum in combination with the positive lens components in the front group and rear group. Further, it is easy to maintain symmetry with respect to the aperture stop, which is advantageous for off-axis aberration correction and for reducing the diameter of the optical system.
さらに、本第２の発明の結像光学系では、バックフォーカスを長くし易くするため、前群を、上述のように、像側から順に、前記明るさ絞り側に向けた凹面を有する正メニスカスレンズ成分と、負レンズ成分と、正レンズ成分を有して構成している。
このように前群を構成すると、結像光学系全体の明るさ絞りに対する対称性を維持しつつ、負レンズ成分の発散作用を物体側に寄せることが出来る。それにより、全体の収差バランスがとり易くなり、かつ、バックフォーカスの確保にも有利となる。
ただし、このような構成において、バックフォーカスを長くしようとすると、前群の正の屈折力が弱くなり易い。
そこで、本第２の発明では、収差をより良好に補正するために、条件式(1)を満足するように構成している。
なお、本第２の発明において、条件式(1)を満足することによる技術的意義は、本第１の発明において述べたとおりである。
Further, in the imaging optical system according to the second aspect of the invention, in order to make the back focus easier, the positive meniscus having a concave surface directed in order from the image side toward the brightness stop side as described above. It has a lens component, a negative lens component, and a positive lens component.
If the front group is configured in this manner, the diverging action of the negative lens component can be brought closer to the object side while maintaining the symmetry of the entire imaging optical system with respect to the aperture stop. Thereby, it becomes easy to balance the entire aberration, and it is advantageous for securing the back focus.
However, in such a configuration, if the back focus is increased, the positive refractive power of the front group tends to be weakened.
Therefore, in the second invention, in order to correct aberrations more favorably, the conditional expression (1) is satisfied.
In the second invention, the technical significance of satisfying conditional expression (1) is as described in the first invention.
なお、条件式(1)の下限値を−３．５とすると、より好ましい。
また、条件式(1)の上限値を−０．８、更には−１．０とすると、より好ましい。
It is more preferable that the lower limit value of conditional expression (1) is −3.5.
Further, it is more preferable that the upper limit value of the conditional expression (1) is −0.8, and further −1.0.
さらに、上記本発明のいずれの結像光学系においても、前記前群の焦点距離をｆＦＧとしたとき、次の条件式(3)を満足するのが好ましい。
２．２＜ｆＦＧ／ｆ＜４０．０ ・・・(3)
ただし、ｆは前記結像光学系全系の焦点距離である。
Further, in any of the imaging optical systems of the present invention, it is preferable that the following conditional expression (3) is satisfied when the focal length of the front group is fFG.
2.2 <fFG / f <40.0 (3)
Here, f is the focal length of the entire imaging optical system.
条件式(3)は、前群の焦点距離を結像光学系全系の焦点距離で規定したものである。
条件式(3)の下限値を下回ると、前群の正の屈折力が強くなりすぎてしまい、バックフォーカスの確保に不利となる。
一方、条件式(3)の上限値を上回ると、前群の正の屈折力が弱くなりすぎてしまい、結像光学系の対称性が崩れ易く収差バランスがとり難くなる。
なお、条件式(3)の下限値を２．４、更には２．５とするとより好ましい。
また、条件式(3)の上限値を３０．０、更には２５．０とするとより好ましい。
Conditional expression (3) defines the focal length of the front group by the focal length of the entire imaging optical system.
If the lower limit of conditional expression (3) is not reached, the positive refractive power of the front group becomes too strong, which is disadvantageous for securing the back focus.
On the other hand, if the upper limit value of conditional expression (3) is exceeded, the positive refractive power of the front group becomes too weak, and the symmetry of the imaging optical system is easily lost, making it difficult to balance aberration.
It is more preferable that the lower limit value of conditional expression (3) is 2.4, more preferably 2.5.
Further, it is more preferable that the upper limit value of the conditional expression (3) is 30.0, further 25.0.
さらに、上記本発明のいずれの結像光学系においても、前記後群の負レンズ成分の像側の面の近軸曲率半径をｒＡＦ、該負レンズ成分の像側に位置する正レンズ成分の物体側の面の近軸曲率半径をｒＡＲとしたとき、次の条件式(4)を満足するのが好ましい。
−０．８＜（ｒＡＦ＋ｒＡＲ）／（ｒＡＦ−ｒＡＲ）＜２．５・・・(4)
Further, in any of the imaging optical systems according to the present invention, the paraxial radius of curvature of the image side surface of the negative lens component of the rear group is rAF, and the object of the positive lens component located on the image side of the negative lens component When the paraxial radius of curvature of the side surface is rAR, it is preferable that the following conditional expression (4) is satisfied.
−0.8 <(rAF + rAR) / (rAF−rAR) <2.5 (4)
条件式(4)は、上述した後群中の第１レンズ成分（即ち、負レンズ成分）と第２レンズ成分（即ち、第１の正レンズ成分）との間の空気レンズの形状を規定した式である。
この空気レンズには、上述の条件式(1)で規定したように、負の屈折力を持たせている。空気レンズの形状は、両凸形状や平凸形状に近いことが好ましい。
条件式(4)の下限値を下回ると、後群の負レンズ成分における像側の凹面の曲率が強くなり、コマ収差等の収差バランスがとり難くなる。
一方、条件式(4)の上限値を上回ると、空気レンズが、両側の曲率が強いメニスカス形状となる。そのため、後群中の負の屈折力を物体側に寄せる機能を十分に得ることが難しくなり、バックフォーカスを長く保ちながらの収差補正が難しくなる。
なお、条件式(4)の下限値を０．０、更には０．５とすると、より好ましい。
また、条件式(4)の上限値を２．０、更には１．５、更には１．１、更には１．０、更には０．９とすると、より好ましい。
また、後群の第１レンズ成分の像側の面を平面、即ち、（ｒＡＦ＋ｒＡＲ）／（ｒＡＦ−ｒＡＲ）＝１とすると、製造上有利となる。
Conditional expression (4) defines the shape of the air lens between the first lens component (ie, negative lens component) and the second lens component (ie, first positive lens component) in the rear group described above. It is a formula.
This air lens has a negative refractive power as defined by the above conditional expression (1). The shape of the air lens is preferably close to a biconvex shape or a plano-convex shape.
If the lower limit of conditional expression (4) is not reached, the curvature of the concave surface on the image side in the negative lens component in the rear group becomes strong, and it becomes difficult to balance aberration such as coma.
On the other hand, when the upper limit value of conditional expression (4) is exceeded, the air lens has a meniscus shape with strong curvature on both sides. For this reason, it becomes difficult to sufficiently obtain the function of bringing the negative refractive power in the rear group toward the object side, and it becomes difficult to correct aberrations while keeping the back focus long.
It is more preferable that the lower limit value of conditional expression (4) is 0.0, and further 0.5.
Further, it is more preferable that the upper limit value of conditional expression (4) is 2.0, further 1.5, further 1.1, further 1.0, and further 0.9.
Further, when the image side surface of the first lens component in the rear group is a plane, that is, (rAF + rAR) / (rAF−rAR) = 1, it is advantageous in manufacturing.
さらに、上記本発明のいずれの結像光学系においても、前記結像レンズの各レンズ間隔の総和をΣｄＡ、前記明るさ絞りを挟む空気レンズの間隔をｄＳとしたとき、次の条件式(5)を満足するのが好ましい。
０．６０＜ｄＳ／ΣｄＡ ・・・(5)
Further, in any of the imaging optical systems of the present invention, when the total distance between the lenses of the imaging lens is ΣdA and the distance between the air lenses sandwiching the aperture stop is dS, the following conditional expression (5 ) Is preferable.
0.60 <dS / ΣdA (5)
条件式(5)の下限値を下回ると、前群、後群の空気間隔が長くなりすぎてしまい、コンパクト化が難しくなる。
あるいは、明るさ絞りを挟む空気レンズの間隔が小さくなりすぎてしまい、諸収差のバランスがとり難くなる。
なお、条件式(5)の下限値を０．６５、更には０．７０とすると、より好ましい。
なお、ｄＳ／ΣｄＡは、１．０以上にはならない。
If the lower limit value of conditional expression (5) is not reached, the air gap between the front group and the rear group becomes too long, making it difficult to make it compact.
Alternatively, the distance between the air lenses that sandwich the aperture stop becomes too small, making it difficult to balance various aberrations.
It is more preferable that the lower limit value of the conditional expression (5) is 0.65, further 0.70.
Note that dS / ΣdA does not exceed 1.0.
さらに、上記本発明のいずれの結像光学系においても、前記前群が、物体側から順に、物体側の面の曲率の絶対値が像側の面の曲率の絶対値よりも大きい正レンズ成分と、物体側に凸面を向けた負メニスカスレンズ成分と、物体側に凸面を向けた正メニスカスレンズ成分とで構成され、前記後群が、物体側から順に、物体側の面の曲率の絶対値が像側の面の曲率の絶対値よりも大きい負レンズ成分と、像側に凸面を向けた正メニスカスレンズ成分と、像側の面の曲率の絶対値が物体側の面の曲率の絶対値よりも大きい正レンズ成分とで構成されるようにするのが好ましい。 Furthermore, in any of the imaging optical systems according to the present invention, the front group includes, in order from the object side, a positive lens component in which the absolute value of the curvature of the object side surface is larger than the absolute value of the curvature of the image side surface. And a negative meniscus lens component having a convex surface facing the object side, and a positive meniscus lens component having a convex surface facing the object side, and the rear group is, in order from the object side, the absolute value of the curvature of the object side surface. The negative lens component is larger than the absolute value of the curvature of the image side surface, the positive meniscus lens component with the convex surface facing the image side, and the absolute value of the curvature of the image side surface is the absolute value of the curvature of the object side surface. It is preferable that the lens is composed of a larger positive lens component.
このように構成すれば、レンズ成分の数を少なく抑えつつ、結像光学系全系における明るさ絞りに対する対称性を良好に確保し、軸外主光線の入射角も小さくすることができ、諸収差の補正に有利となる。
また、前群内のレンズ成分のパワー配置を上述の正、負、正の配置とすることで、結像光学系全系の対称性を確保しつつも、負レンズ成分の発散作用を物体側に寄せることができバックフォーカスも長くし易くなる。
With this configuration, it is possible to secure good symmetry with respect to the aperture stop in the entire imaging optical system while reducing the number of lens components, and to reduce the incident angle of the off-axis principal ray. This is advantageous for correcting aberrations.
In addition, by setting the power arrangement of the lens components in the front group to the above-described positive, negative, and positive arrangements, the divergence of the negative lens components can be achieved on the object side while ensuring the symmetry of the entire imaging optical system. And the back focus can be easily extended.
さらに、上記本発明のいずれの結像光学系においても、前記前群における最も像側のレンズ成分が正の屈折力を有し、前記前群の入射面から前記前群における最も像側のレンズ成分の直前のレンズ成分までが負の屈折力を持ち、前記前群における最も像側のレンズ成分とその直前のレンズ成分との空気間隔をｄＡ２としたとき、次の条件式(6)を満足するのが好ましい。
０．０３５＜ｄＡ２／ｆ＜０．１ ・・・(6)
ただし、ｆは前記結像光学系全系の焦点距離である。
Furthermore, in any of the imaging optical systems according to the present invention, the most image side lens component in the front group has a positive refractive power, and the most image side lens in the front group from the entrance surface of the front group. The lens component immediately before the component has negative refractive power, and the following conditional expression (6) is satisfied, where dA2 is the air space between the lens component closest to the image side in the front group and the lens component immediately before the lens component: It is preferable to do this.
0.035 <dA2 / f <0.1 (6)
Here, f is the focal length of the entire imaging optical system.
前群をこのようなパワー配置で構成すると、早い段階（即ち、より物体側に寄った位置）で発散作用を持たせることができ、バックフォーカスの確保に有利となる。
条件式(6)の下限値を下回ると、空気間隔ｄＡ２が小さくなりすぎてしまい、焦点距離に対するバックフォーカスを長くする機能が低下してしまう。
一方、条件式(6)の上限値を上回ると、空気間隔ｄＡ２が長くなりすぎてしまい、コンパクト化に不利となる。また、光学系の対称性が崩れ易くなり、負のディストーション等を抑えることが難しくなる。
なお、条件式(6)の下限値を０．０４、更には０．０４３とすると、より好ましい。
また、条件式(6)の上限値を０．０８、更には０．０６とすると、より好ましい。
When the front group is configured with such a power arrangement, a diverging action can be provided at an early stage (that is, a position closer to the object side), which is advantageous in securing a back focus.
If the lower limit value of conditional expression (6) is not reached, the air gap dA2 becomes too small, and the function of increasing the back focus with respect to the focal length is degraded.
On the other hand, if the upper limit value of conditional expression (6) is exceeded, the air gap dA2 becomes too long, which is disadvantageous for downsizing. In addition, the symmetry of the optical system is easily broken, and it becomes difficult to suppress negative distortion and the like.
It is more preferable that the lower limit value of conditional expression (6) is 0.04, and further 0.043.
Further, it is more preferable that the upper limit value of conditional expression (6) is 0.08, more preferably 0.06.
さらに、上記本発明のいずれの結像光学系においても、前記後群の第１の正レンズ成分の焦点距離をｆＲＰ１、前記後群の第２の正レンズ成分の焦点距離をｆＲＰ２としたとき、次の条件式(7)を満足するのが好ましい。
０．８＜ｆＲＰ１／ｆＲＰ２＜２．０ ・・・(7)
Furthermore, in any of the imaging optical systems of the present invention, when the focal length of the first positive lens component in the rear group is fRP1, and the focal length of the second positive lens component in the rear group is fRP2, It is preferable that the following conditional expression (7) is satisfied.
0.8 <fRP1 / fRP2 <2.0 (7)
前記後群における第１の正レンズ成分と第２の正レンズ成分との屈折力比を、条件式(7)を満足するようにすれば、光学性能を良好に維持したままバックフォーカスを長くすることが可能となる。
条件式(7)の上限値を上回ると、バックフォーカスを長くすることに対しては有利となるが、後群における第２の正レンズ成分の屈折力が強くなりすぎてしまい、アンダーの球面収差が出易くなる。また、第２の正レンズ成分でのコマ収差が発生し易くなってしまう。
一方、条件式(7)の下限値を下回ると、後群における第１の正レンズ成分の屈折力が強くなりすぎてしまい、バックフォーカスの確保に不利となる。また、第１の正レンズ成分の直前に形成される空気レンズの負の屈折力を確保しようとすると、第１の正レンズ成分の像側の面の曲率が大きくなり易く、この面での収差が発生し易くなってしまう。
なお、条件式(7)の下限値を０．８５とすると、より好ましい。
また、条件式(7)の上限値を１．７、更には、１．６とすると、より好ましい、
If the refractive power ratio between the first positive lens component and the second positive lens component in the rear group satisfies the conditional expression (7), the back focus is lengthened while maintaining good optical performance. It becomes possible.
If the upper limit value of conditional expression (7) is exceeded, it is advantageous for increasing the back focus, but the refractive power of the second positive lens component in the rear group becomes too strong, resulting in under spherical aberration. Becomes easy to come out. Further, coma aberration is likely to occur in the second positive lens component.
On the other hand, if the lower limit value of conditional expression (7) is not reached, the refractive power of the first positive lens component in the rear group becomes too strong, which is disadvantageous for securing the back focus. Further, if the negative refractive power of the air lens formed immediately before the first positive lens component is to be secured, the curvature of the image-side surface of the first positive lens component tends to increase, and aberrations on this surface Is likely to occur.
It is more preferable that the lower limit value of conditional expression (7) is 0.85.
Further, it is more preferable that the upper limit value of conditional expression (7) is 1.7, and further 1.6.
さらに、上記本発明のいずれの結像光学系においても、前記前群が、該前群において最も物体側に配置された正レンズと、その正レンズの像側に配置された、正レンズと負レンズを有するのが好ましい。 Furthermore, in any of the imaging optical systems according to the present invention, the front group includes a positive lens disposed closest to the object side in the front group, and a positive lens and a negative lens disposed on the image side of the positive lens. It is preferable to have a lens.
このように構成すれば、前群と後群を明るさ絞りに対して対称的な配置に近づけることができ、諸収差の補正に有利となる。 With this configuration, the front group and the rear group can be brought close to a symmetrical arrangement with respect to the aperture stop, which is advantageous in correcting various aberrations.
さらに、上記本発明のいずれの結像光学系においても、前記前群が、物体側から順に、正レンズと、負レンズと、正レンズの３枚のレンズからなるのが好ましい。 Furthermore, in any of the imaging optical systems according to the present invention, it is preferable that the front group includes three lenses of a positive lens, a negative lens, and a positive lens in order from the object side.
一般的なガウスタイプの前群の構成としては、正レンズ、正レンズ、負レンズの順で構成されるものが主流であるが、物体側から二番目のレンズに関し、正レンズと負レンズとを入れ替えると、負レンズ成分の発散作用を物体側に寄せることができ、バックフォーカスの確保に有利となる。 As a general Gauss type front group configuration, the mainstream is composed of a positive lens, a positive lens, and a negative lens, but the second lens from the object side has a positive lens and a negative lens. If switched, the diverging action of the negative lens component can be brought closer to the object side, which is advantageous for securing the back focus.
さらに、上記本発明のいずれの結像光学系においても、無限遠合焦状態から近距離合焦を行う際に前記前群と前記後群との間隔が変化するように構成するのが好ましい。 Furthermore, in any of the imaging optical systems according to the present invention, it is preferable that the distance between the front group and the rear group is changed when focusing at a short distance from the infinite focus state.
明るさ絞りが配置される空間を変化させるフローティングを行うと、光学性能の維持が容易となり、マクロレンズとしての使用が可能となる。
具体的には、至近合焦側で発生し易いコマ収差の補正に有利となり、例えば、等倍撮影付近まで光学性能の確保が可能となる。
If floating is performed to change the space in which the aperture stop is arranged, the optical performance can be easily maintained and the lens can be used as a macro lens.
Specifically, it is advantageous for correction of coma that is likely to occur on the close-up focus side, and for example, it is possible to ensure optical performance up to near the same magnification photographing.
さらに、上記本発明のいずれの結像光学系においても、前記後群のレンズが、全て単レンズで構成されているのが好ましい。 Furthermore, in any of the imaging optical systems according to the present invention, it is preferable that all the lenses in the rear group are constituted by a single lens.
上述したように本発明のいずれの結像光学系も、レンズ枚数を少なくしても光学性能を良好に確保することができる構成となっている。そこで、上述のように前記後群のレンズを全て単レンズで構成すれば、光学性能を良好に確保しつつ、コスト低減、小型軽量化に有利となる。 As described above, any of the imaging optical systems of the present invention has a configuration that can ensure good optical performance even if the number of lenses is reduced. Therefore, if all the rear group lenses are configured as a single lens as described above, it is advantageous for cost reduction and reduction in size and weight while ensuring good optical performance.
さらに、上記本発明のいずれの結像光学系においても、前記前群のレンズが、全て単レンズで構成されているのが好ましい。 Furthermore, in any of the imaging optical systems according to the present invention, it is preferable that all the lenses in the front group are constituted by a single lens.
上述したように本発明のいずれの結像光学系も、レンズ枚数を少なくしても光学性能を良好に確保することができる構成となっている。そこで、さらに、上述のように前記前群のレンズを全て単レンズで構成すれば、光学性能を良好に確保しつつ、コスト低減、小型軽量化に有利となる。 As described above, any of the imaging optical systems of the present invention has a configuration that can ensure good optical performance even if the number of lenses is reduced. Therefore, further, if all the lenses in the front group are constituted by a single lens as described above, it is advantageous for cost reduction and reduction in size and weight while ensuring good optical performance.
さらに、本発明の結像光学系を備えた交換レンズ装置は、上記本発明のいずれかの結像光学系と、該結像光学系をカメラ本体に取り付け可能とするマウント部を備えたことを特徴としている。 Furthermore, an interchangeable lens apparatus provided with the imaging optical system of the present invention includes any one of the imaging optical systems of the present invention described above and a mount portion that allows the imaging optical system to be attached to the camera body. It is a feature.
上述したように、上記本発明の結像光学系は、いずれもバックフォーカスの確保と光学性能とのバランスが良好にとることができる。このため、上記本発明のいずれの結像光学系は、例えば、クイックリターンミラー、ローパスフィルターなどを結像光学系の像側に結像光学系を配置するような構成の光学装置に適用すると有用である。
そのような使用形態の１つとして、上述の交換レンズ装置に用いると好適である。
As described above, any of the imaging optical systems of the present invention can achieve a good balance between ensuring back focus and optical performance. For this reason, any of the imaging optical systems of the present invention is useful when applied to an optical apparatus having a configuration in which, for example, a quick return mirror, a low-pass filter, and the like are arranged on the image side of the imaging optical system. It is.
As one of such usage forms, it is suitable for use in the above-described interchangeable lens device.
なお、上述した本発明の結像光学系の各構成は、当該結像光学系の無限遠物点に対して合焦を行った状態での構成である。
また、上述した本発明の結像光学系の各構成は、任意に組み合わせて同時に満足させるようにするのが好ましい。
Each configuration of the imaging optical system of the present invention described above is a configuration in a state where focusing is performed on an object point at infinity of the imaging optical system.
In addition, it is preferable that the above-described configurations of the imaging optical system of the present invention are arbitrarily combined and simultaneously satisfied.
さらには、本発明の結像光学系は、次のように構成してもよい。
物体側から順に、正の屈折力を持つ前群と、明るさ絞りと、正の屈折力を持つ後群とからなり、前記前群が、像側から順に、前記明るさ絞り側に向けた凹面を有する正メニスカスレンズ成分と、負レンズ成分と、正レンズ成分を有し、前記後群が、物体側から順に、前記明るさ絞り側に向けた凹面を有する負レンズ成分と、正レンズ成分と、正レンズ成分を有し、次の条件式(2-1)を満足することを特徴とする結像光学系。
０．９５＜ｆｂ／ｆ＜１．５ ・・・(2-1)
ただし、ｆは結像光学系全系の焦点距離、ｆｂは後群における最も像側レンズの射出面から焦点までの光軸上での空気換算距離、である。
また、ここでのレンズ成分は、いずれも、光軸上において、各レンズ成分における最も物体側の面と最も像側の面のみが空気と接し、それらの面の間が空気と接しない、単レンズ又は接合レンズを意味する。
Furthermore, the imaging optical system of the present invention may be configured as follows.
In order from the object side, the front group has a positive refractive power, an aperture stop, and a rear group having a positive refractive power, and the front group is directed from the image side to the brightness stop side. A positive meniscus lens component having a concave surface, a negative lens component, a positive lens component, and a negative lens component having a concave surface directed toward the brightness stop side in order from the object side, and the positive lens component And an imaging optical system having a positive lens component and satisfying the following conditional expression (2-1):
0.95 <fb / f <1.5 (2-1)
Here, f is the focal length of the entire imaging optical system, and fb is the air equivalent distance on the optical axis from the exit surface of the image side lens to the focal point in the rear group.
In addition, all the lens components here are on the optical axis, only the most object-side surface and the most image-side surface of each lens component are in contact with air, and those surfaces are not in contact with air. It means a lens or a cemented lens.
次に、本発明の実施例について図面を用いて説明する。
図１は本発明の実施例１にかかる結像光学系の光学構成を示す光軸に沿う断面図であり、(a)は無限遠合焦時の状態、（b）は近距離合焦時の状態（至近状態（等倍））を夫々示している。図２は実施例１にかかる結像光学系の球面収差、非点収差、歪曲収差、倍率色収差を示すグラフであり、(a)は無限遠合焦時の状態、（b）は近距離合焦時の状態（至近状態（等倍））を夫々示している。
Next, embodiments of the present invention will be described with reference to the drawings.
1A and 1B are cross-sectional views along the optical axis showing the optical configuration of the imaging optical system according to Example 1 of the present invention. FIG. 1A is a state at the time of focusing at infinity, and FIG. (Close-up state (same size)) is shown. 2A and 2B are graphs showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the imaging optical system according to Example 1. FIG. 2A is a state at the time of focusing on infinity, and FIG. Each state of focus (close-up state (equal magnification)) is shown.
実施例１の結像光学系は、物体側から順に、正の屈折力を持つ前群Ｇ１と、明るさ絞りＳと、正の屈折力を持つ後群Ｇ２とで構成されている。なお、図１中、ＩＭは結像面である。
前群Ｇ１は、物体側から順に、（明るさ絞りＳ側に向けた凹面を有する前群Ｇ１における最も像側のレンズ成分よりも物体側に配置された正レンズ成分としての）物体側に凸面を向けた正メニスカスレンズＬ１１と、（負レンズ成分としての）物体側に凸面を向けた負メニスカスレンズＬ１２と、（明るさ絞りＳ側に向けた凹面を有する、前群Ｇ１における最も像側の正メニスカスレンズ成分としての）物体側に凸面を向けた正メニスカスレンズＬ１３とで構成されている。正メニスカスレンズＬ１１は、物体側の面の曲率の絶対値が像側の面の曲率の絶対値よりも大きくなるように（即ち、物体側の面の曲率半径ｒ1の絶対値が像側の面の曲率半径ｒ2の絶対値よりも小さくなるように）形成されている。また、これらのレンズＬ１１〜Ｌ１３は、全て単レンズで構成されている。また、前群Ｇ１は、レンズＬ１１からレンズＬ１２までにかけて負の屈折力を持っている。
The imaging optical system according to the first exemplary embodiment includes, in order from the object side, a front group G1 having a positive refractive power, an aperture stop S, and a rear group G2 having a positive refractive power. In FIG. 1, IM is an image plane.
The front group G1 is convex from the object side to the object side (as a positive lens component disposed on the object side relative to the most image-side lens component in the front group G1 having a concave surface directed toward the aperture stop S). A positive meniscus lens L11 facing the lens, a negative meniscus lens L12 having a convex surface facing the object side (as a negative lens component), and the most image-side lens in the front group G1 having a concave surface facing the aperture stop S side. And a positive meniscus lens L13 having a convex surface on the object side (as a positive meniscus lens component). In the positive meniscus lens L11, the absolute value of the curvature of the object side surface is larger than the absolute value of the curvature of the image side surface (that is, the absolute value of the curvature radius r 1 of the object side surface is the image side surface). It is formed so as to be smaller than the absolute value of the radius of curvature r 2 of the surface. These lenses L11 to L13 are all constituted by a single lens. The front group G1 has a negative refractive power from the lens L11 to the lens L12.
後群Ｇ２は、物体側から順に、（明るさ絞りＳ側に凹面を向けた負レンズ成分としての）物体側が凹面で像側が平面の平凹レンズＬ２１と、（第１の正レンズ成分としての）物体側に凹面を向けた正メニスカスレンズＬ２２と、（第２の正レンズ成分としての）両凸レンズＬ２３とで構成されている。両凸レンズＬ２３は、像側の面の曲率の絶対値が物体側の面の曲率の絶対値より大きくなるように（即ち、像側の面の曲率半径ｒ13の絶対値が物体側の面の曲率半径ｒ12の絶対値より小さくなるように）形成されている。また、これらのレンズＬ２１〜Ｌ２３は、全て単レンズで構成されている。
また、無限遠合焦状態から近距離合焦を行う際に、前群Ｇ１と後群Ｇ２は、ともに物体側に移動し、且つ、互いの間隔が広がるようになっている。
The rear group G2, in order from the object side, is a plano-concave lens L21 having a concave surface on the object side and a plane on the image side (as a negative lens component with a concave surface facing the aperture stop S), and (as a first positive lens component). The lens includes a positive meniscus lens L22 having a concave surface facing the object side, and a biconvex lens L23 (as a second positive lens component). Biconvex lens L23, as the absolute value of the curvature of the image side surface is greater than the absolute value of the curvature of the object-side surface (i.e., the absolute value of the curvature radius r 13 of the surface on the image side of the surface on the object side It is formed so as to be smaller than the absolute value of the curvature radius r 12 . These lenses L21 to L23 are all constituted by a single lens.
Further, when performing short-distance focusing from the infinitely focused state, both the front group G1 and the rear group G2 move to the object side, and the mutual interval is widened.
次に、実施例１の結像光学系を構成する光学部材の数値データを示す。数値データ中、ｒ1、ｒ2、・・・は光学部材の曲率半径、ｄ1、ｄ2、・・・は光学部材の面間隔（肉厚又は空気間隔）、ｎd1、ｎd2、・・・は光学部材のｄ線での屈折率、νd1、νd2、・・・は光学部材のｄ線でのアッベ数、ｆは焦点距離、ＦＮＯはＦナンバー、ＩＨは像高、ωは半画角である。これらは以下の各実施例の数値データにおいて共通である。
また、実施例１の数値データは、無限遠合焦時と、近距離合焦時（至近状態（等倍））のそれぞれにおけるデータである。
Next, numerical data of optical members constituting the imaging optical system of Example 1 are shown. In the numerical data, r 1 , r 2 ,... Are the radius of curvature of the optical member, d 1 , d 2 ,... Are the surface spacing (thickness or air spacing) of the optical member, n d1 , n d2,. .. is the refractive index of the optical member at the d-line, .nu.d1 , .nu.d2 ,... Is the Abbe number of the optical member at the d-line, f is the focal length, FNO is the F number, IH is the image height, and .omega. Half angle of view. These are common in the numerical data of the following embodiments.
In addition, the numerical data of the first embodiment is data at each time of focusing on infinity and focusing on a short distance (closest state (equal magnification)).
数値データ１（実施例１）
焦点距離（ｆ） ３５．５９ｍｍ
Ｆナンバー（ＦＮＯ） ２．７９３
像高（ＩＨ） １１．１５ｍｍ
半画角（ω） １７．６°
至近状態（等倍）での像側の面の面頂から結像面までの距離（空気換算距離） 70.79mm
ｒ1＝31.402
ｄ1＝2.20 ｎd1＝1.8044 νd1＝39.59
ｒ2＝103.805
ｄ2＝0.20
ｒ3＝18.004
ｄ3＝1.23 ｎd3＝1.58267 νd3＝46.42
ｒ4＝10.237
ｄ4＝1.64
ｒ5＝10.612
ｄ5＝2.12 ｎd5＝1.757 νd5＝47.82
ｒ6＝11.886
ｄ6＝3.19
ｒ7＝∞（明るさ絞り）
ｄ7＝Ｄ７
ｒ8＝-12.458
ｄ8＝2.00 ｎd8＝1.78472 νd8＝25.68
ｒ9＝∞
ｄ9＝0.50
ｒ10＝-46.137
ｄ10＝3.30 ｎd10＝1.7725 νd10＝49.6
ｒ11＝-16.376
ｄ11＝0.35
ｒ12＝111.996
ｄ12＝3.30 ｎd12＝1.51633 νd12＝49.6
ｒ13＝-16.376
ｄ13＝-23.531
Numerical data 1 (Example 1)
Focal length (f) 35.59mm
F number (FNO) 2.793
Image height (IH) 11.15mm
Half angle of view (ω) 17.6 °
Distance from the top of the image side surface to the imaging surface in close-up state (same size) (air conversion distance) 70.79mm
r 1 = 31.402
d 1 = 2.20 n d1 = 1.8044 ν d1 = 39.59
r 2 = 103.805
d 2 = 0.20
r 3 = 18.004
d 3 = 1.23 n d3 = 1.58267 ν d3 = 46.42
r 4 = 10.237
d 4 = 1.64
r 5 = 10.612
d 5 = 2.12 n d5 = 1.757 ν d5 = 47.82
r 6 = 11.886
d 6 = 3.19
r 7 = ∞ (brightness stop)
d 7 = D7
r 8 = -12.458
d 8 = 2.00 n d8 = 1.78472 ν d8 = 25.68
r 9 = ∞
d 9 = 0.50
r 10 = -46.137
d 10 = 3.30 n d10 = 1.7725 ν d10 = 49.6
r 11 = -16.376
d 11 = 0.35
r 12 = 111.996
d 12 = 3.30 n d12 = 1.51633 ν d12 = 49.6
r 13 = -16.376
d 13 = -23.531
図３は本発明の実施例２にかかる結像光学系の光学構成を示す光軸に沿う断面図であり、無限遠合焦時の状態を示している。図４は実施例２にかかる結像光学系の球面収差、非点収差、歪曲収差、倍率色収差を示すグラフであり、無限遠合焦時の状態を示している。 FIG. 3 is a cross-sectional view along the optical axis showing the optical configuration of the imaging optical system according to Example 2 of the present invention, and shows a state at the time of focusing on infinity. FIG. 4 is a graph showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the imaging optical system according to Example 2, and shows a state at the time of focusing on infinity.
実施例２の結像光学系は、物体側から順に、正の屈折力を持つ前群Ｇ１と、明るさ絞りＳと、正の屈折力を持つ後群Ｇ２とで構成されている。
前群Ｇ１は、物体側から順に、（明るさ絞りＳ側に向けた凹面を有する前群Ｇ１における最も像側のレンズ成分よりも物体側に配置された正レンズ成分としての）物体側に凸面を向けた正メニスカスレンズＬ１１と、（負レンズ成分としての）物体側に凸面を向けた負メニスカスレンズＬ１２と、（明るさ絞りＳ側に向けた凹面を有する、前群Ｇ１における最も像側の正メニスカスレンズ成分としての）物体側に凸面を向けた正メニスカスレンズＬ１３とで構成されている。正メニスカスレンズＬ１１は、物体側の面の曲率の絶対値が像側の面の曲率の絶対値よりも大きくなるように（即ち、物体側の面の曲率半径ｒ1の絶対値が像側の面の曲率半径ｒ2の絶対値よりも小さくなるように）形成されている。また、これらのレンズＬ１１〜Ｌ１３は、全て単レンズで構成されている。また、前群Ｇ１は、レンズＬ１１からレンズＬ１２までにかけて負の屈折力を持っている。
The imaging optical system according to the second embodiment includes, in order from the object side, a front group G1 having a positive refractive power, an aperture stop S, and a rear group G2 having a positive refractive power.
The front group G1 is convex from the object side to the object side (as a positive lens component disposed on the object side relative to the most image-side lens component in the front group G1 having a concave surface directed toward the aperture stop S). A positive meniscus lens L11 facing the lens, a negative meniscus lens L12 having a convex surface facing the object side (as a negative lens component), and the most image-side lens in the front group G1 having a concave surface facing the aperture stop S side. And a positive meniscus lens L13 having a convex surface on the object side (as a positive meniscus lens component). In the positive meniscus lens L11, the absolute value of the curvature of the object side surface is larger than the absolute value of the curvature of the image side surface (that is, the absolute value of the curvature radius r 1 of the object side surface is the image side surface). It is formed so as to be smaller than the absolute value of the radius of curvature r 2 of the surface. These lenses L11 to L13 are all constituted by a single lens. The front group G1 has a negative refractive power from the lens L11 to the lens L12.
後群Ｇ２は、物体側から順に、（明るさ絞りＳ側に凹面を向けた負レンズ成分としての）両凹レンズＬ２１’と、（第１の正レンズ成分としての）物体側に凹面を向けた正メニスカスレンズＬ２２と、（第２の正レンズ成分としての）両凸レンズＬ２３とで構成されている。両凹レンズＬ２１’は、物体側の面の曲率の絶対値が像側の面の曲率の絶対値よりも大きくなるように（即ち、物体側の面の曲率半径ｒ8の絶対値が像側の面の曲率半径ｒ9の絶対値よりも小さくなるように）形成されている。両凸レンズＬ２３は、像側の面の曲率の絶対値が物体側の面の曲率の絶対値より大きくなるように（即ち、像側の面の曲率半径ｒ13の絶対値が物体側の面の曲率半径ｒ12の絶対値より小さくなるように）形成されている。また、これらのレンズＬ２１’〜Ｌ２３は、全て単レンズで構成されている。 The rear group G2, in order from the object side, has a biconcave lens L21 ′ (as a negative lens component with a concave surface facing the aperture stop S) and a concave surface toward the object side (as a first positive lens component). It is composed of a positive meniscus lens L22 and a biconvex lens L23 (as a second positive lens component). The biconcave lens L21 ′ is configured such that the absolute value of the curvature of the object-side surface is larger than the absolute value of the curvature of the image-side surface (that is, the absolute value of the curvature radius r 8 of the object-side surface is on the image side). It is formed so as to be smaller than the absolute value of the radius of curvature r 9 of the surface). Biconvex lens L23, as the absolute value of the curvature of the image side surface is greater than the absolute value of the curvature of the object-side surface (i.e., the absolute value of the curvature radius r 13 of the surface on the image side of the surface on the object side It is formed so as to be smaller than the absolute value of the curvature radius r 12 . These lenses L21 ′ to L23 are all constituted by a single lens.
次に、実施例２の結像光学系を構成する光学部材の数値データを示す。
実施例２の数値データは、無限遠合焦時におけるデータである。
数値データ２（実施例２）
焦点距離（ｆ） ３０．５０ｍｍ
Ｆナンバー（ＦＮＯ） ３．２９０
像高（ＩＨ） １１．１５ｍｍ
半画角（ω） ２０．７°
ｒ1＝39.0231
ｄ1＝2.20 ｎd1＝1.8044 νd1＝39.59
ｒ2＝124.3583
ｄ2＝0.20
ｒ3＝21.8137
ｄ3＝1.23 ｎd3＝1.497 νd3＝81.54
ｒ4＝9.0005
ｄ4＝1.69
ｒ5＝10.6888
ｄ5＝2.12 ｎd5＝1.757 νd5＝47.82
ｒ6＝13.3166
ｄ6＝3.19
ｒ7＝∞（明るさ絞り）
ｄ7＝5.21
ｒ8＝-12.5403
ｄ8＝2.00 ｎd8＝1.84666 νd8＝23.78
ｒ9＝782.1809
ｄ9＝0.50
ｒ10＝-93.024
ｄ10＝3.30 ｎd10＝1.7725 νd10＝49.6
ｒ11＝-15.1073
ｄ11＝0.35
ｒ12＝120.3961
ｄ12＝3.30 ｎd12＝1.7725 νd12＝49.6
ｒ13＝-23.6548
Next, numerical data of optical members constituting the imaging optical system of Example 2 are shown.
The numerical data of the second embodiment is data at the time of focusing on infinity.
Numerical data 2 (Example 2)
Focal length (f) 30.50mm
F number (FNO) 3.290
Image height (IH) 11.15mm
Half angle of view (ω) 20.7 °
r 1 = 39.0231
d 1 = 2.20 n d1 = 1.8044 ν d1 = 39.59
r 2 = 124.3583
d 2 = 0.20
r 3 = 21.8137
d 3 = 1.23 n d3 = 1.497 ν d3 = 81.54
r 4 = 9.0005
d 4 = 1.69
r 5 = 10.6888
d 5 = 2.12 n d5 = 1.757 ν d5 = 47.82
r 6 = 13.3166
d 6 = 3.19
r 7 = ∞ (brightness stop)
d 7 = 5.21
r 8 = -12.5403
d 8 = 2.00 n d8 = 1.84666 ν d8 = 23.78
r 9 = 782.1809
d 9 = 0.50
r 10 = -93.024
d 10 = 3.30 n d10 = 1.7725 ν d10 = 49.6
r 11 = -15.1073
d 11 = 0.35
r 12 = 120.3961
d 12 = 3.30 n d12 = 1.7725 ν d12 = 49.6
r 13 = -23.6548
図５は本発明の実施例３にかかる結像光学系の光学構成を示す光軸に沿う断面図であり、無限遠合焦時の状態を示している。図６は実施例３にかかる結像光学系の球面収差、非点収差、歪曲収差、倍率色収差を示すグラフであり、無限遠合焦時の状態を示している。 FIG. 5 is a sectional view along the optical axis showing the optical configuration of the imaging optical system according to Example 3 of the present invention, and shows a state at the time of focusing on infinity. FIG. 6 is a graph showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration of the imaging optical system according to Example 3, and shows a state at the time of focusing on infinity.
実施例３の結像光学系は、物体側から順に、正の屈折力を持つ前群Ｇ１と、明るさ絞りＳと、正の屈折力を持つ後群Ｇ２とで構成されている。
前群Ｇ１は、物体側から順に、（明るさ絞りＳ側に向けた凹面を有する前群Ｇ１における最も像側のレンズ成分よりも物体側に配置された正レンズ成分としての）物体側に凸面を向けた正メニスカスレンズＬ１１と、（負レンズ成分としての）物体側に凸面を向けた負メニスカスレンズＬ１２と、（明るさ絞りＳ側に向けた凹面を有する、前群Ｇ１における最も像側の正メニスカスレンズ成分としての）物体側に凸面を向けた正メニスカスレンズＬ１３とで構成されている。正メニスカスレンズＬ１１は、物体側の面の曲率の絶対値が像側の面の曲率の絶対値よりも大きくなるように（即ち、物体側の面の曲率半径ｒ1の絶対値が像側の面の曲率半径ｒ2の絶対値よりも小さくなるように）形成されている。また、これらのレンズＬ１１〜Ｌ１３は、全て単レンズで構成されている。また、前群Ｇ１は、レンズＬ１１からレンズＬ１２までにおいて負の屈折力を持っている。
The imaging optical system according to the third exemplary embodiment includes, in order from the object side, a front group G1 having a positive refractive power, an aperture stop S, and a rear group G2 having a positive refractive power.
The front group G1 is convex from the object side to the object side (as a positive lens component disposed on the object side relative to the most image-side lens component in the front group G1 having a concave surface directed toward the aperture stop S). A positive meniscus lens L11 facing the lens, a negative meniscus lens L12 having a convex surface facing the object side (as a negative lens component), and the most image-side lens in the front group G1 having a concave surface facing the aperture stop S side. And a positive meniscus lens L13 having a convex surface on the object side (as a positive meniscus lens component). In the positive meniscus lens L11, the absolute value of the curvature of the object side surface is larger than the absolute value of the curvature of the image side surface (that is, the absolute value of the curvature radius r 1 of the object side surface is the image side surface). It is formed so as to be smaller than the absolute value of the radius of curvature r 2 of the surface. These lenses L11 to L13 are all constituted by a single lens. The front group G1 has a negative refractive power from the lens L11 to the lens L12.
後群Ｇ２は、物体側から順に、（明るさ絞りＳ側に凹面を向けた負レンズ成分としての）両凹レンズＬ２１’と、（第１の正レンズ成分としての）物体側に凹面を向けた正メニスカスレンズＬ２２と、（第２の正レンズ成分としての）両凸レンズＬ２３とで構成されている。両凹レンズＬ２１’は、物体側の面の曲率の絶対値が像側の面の曲率の絶対値よりも大きくなるように（即ち、物体側の面の曲率半径ｒ8の絶対値が像側の面ｒ9の曲率半径の絶対値よりも小さくなるように）形成されている。両凸レンズＬ２３は、像側の面の曲率の絶対値が物体側の面の曲率の絶対値より大きくなるように（即ち、像側の面の曲率半径ｒ13の絶対値が物体側の面の曲率半径ｒ12の絶対値より小さくなるように）形成されている。また、これらのレンズＬ２１’〜Ｌ２３は、全て単レンズで構成されている。 The rear group G2, in order from the object side, has a biconcave lens L21 ′ (as a negative lens component with a concave surface facing the aperture stop S) and a concave surface toward the object side (as a first positive lens component). It is composed of a positive meniscus lens L22 and a biconvex lens L23 (as a second positive lens component). The biconcave lens L21 ′ is configured such that the absolute value of the curvature of the object-side surface is larger than the absolute value of the curvature of the image-side surface (that is, the absolute value of the curvature radius r 8 of the object-side surface is on the image side). and as) is formed smaller than the absolute value of the curvature radius of the surface r 9. Biconvex lens L23, as the absolute value of the curvature of the image side surface is greater than the absolute value of the curvature of the object-side surface (i.e., the absolute value of the curvature radius r 13 of the surface on the image side of the surface on the object side It is formed so as to be smaller than the absolute value of the curvature radius r 12 . These lenses L21 ′ to L23 are all constituted by a single lens.
次に、実施例３の結像光学系を構成する光学部材の数値データを示す。
実施例３の数値データは、無限遠合焦時におけるデータである。
Next, numerical data of optical members constituting the imaging optical system of Example 3 are shown.
The numerical data of the third embodiment is data at the time of focusing on infinity.
数値データ３（実施例３）
焦点距離（ｆ） ３０．６０ｍｍ
Ｆナンバー（ＦＮＯ） ２．８０
像高（ＩＨ） １１．１５ｍｍ
半画角（ω） １７．５°
ｒ1＝34.1904
ｄ1＝2.50 ｎd1＝1.8044 νd1＝39.59
ｒ2＝178.6685
ｄ2＝0.20
ｒ3＝18.735
ｄ3＝1.23 ｎd3＝1.58267 νd3＝46.42
ｒ4＝10.2208
ｄ4＝1.70
ｒ5＝11.5169
ｄ5＝2.12 ｎd5＝1.757 νd5＝47.82
ｒ6＝13.9416
ｄ6＝2.71
ｒ7＝∞（明るさ絞り）
ｄ7＝5.35
ｒ8＝-13.1851
ｄ8＝2.00 ｎd8＝1.78472 νd8＝25.68
ｒ9＝225.1578
ｄ9＝0.70
ｒ10＝-38.2218
ｄ10＝3.30 ｎd10＝1.7725 νd10＝49.6
ｒ11＝-16.9776
ｄ11＝0.20
ｒ12＝159.7236
ｄ12＝3.30 ｎd12＝1.7725 νd12＝49.6
ｒ13＝-20.7761
Numerical data 3 (Example 3)
Focal length (f) 30.60mm
F number (FNO) 2.80
Image height (IH) 11.15mm
Half angle of view (ω) 17.5 °
r 1 = 34.1904
d 1 = 2.50 n d1 = 1.8044 ν d1 = 39.59
r 2 = 178.6685
d 2 = 0.20
r 3 = 18.735
d 3 = 1.23 n d3 = 1.58267 ν d3 = 46.42
r 4 = 10.2208
d 4 = 1.70
r 5 = 11.5169
d 5 = 2.12 n d5 = 1.757 ν d5 = 47.82
r 6 = 13.9416
d 6 = 2.71
r 7 = ∞ (brightness stop)
d 7 = 5.35
r 8 = -13.1851
d 8 = 2.00 n d8 = 1.78472 ν d8 = 25.68
r 9 = 225.1578
d 9 = 0.70
r 10 = -38.2218
d 10 = 3.30 n d10 = 1.7725 ν d10 = 49.6
r 11 = -16.9776
d 11 = 0.20
r 12 = 159.7236
d 12 = 3.30 n d12 = 1.7725 ν d12 = 49.6
r 13 = -20.7761
次に、各実施例における条件式の数値パラメータ対応値を次の表１に示す。
以上説明した本発明の結像光学系は、それを備えた交換レンズ装置として、その結像光学系で結像した物体像をＣＣＤやＣＭＯＳ等の撮像素子に受光されて撮影を行う電子撮像装置、特にレンズ交換式のデジタル一眼レフカメラに用いることができる。以下に、その実施形態を例示する。 The imaging optical system of the present invention described above is an electronic imaging apparatus that takes an image of an object image formed by the imaging optical system as received by an imaging element such as a CCD or CMOS as an interchangeable lens apparatus provided with the imaging optical system. In particular, it can be used for an interchangeable lens digital single-lens reflex camera. The embodiment is illustrated below.
図７は本発明の結像光学系を備えた交換レンズ装置として、撮影レンズに用いた一眼レフレックスカメラの断面図である。図７において、１は一眼レフレックスカメラ、２は撮影レンズ、３は撮影レンズ２を一眼レフレックスカメラ１に着脱可能とするマウント部であり、スクリュータイプのマウントやバヨネットマウント等が用いられる。この例では、バヨネットタイプのマウントを用いている。また、４は受光面、５は撮影レンズ２の光路６上のレンズ系と受光面４との間に配置されたクイックリターンミラー、７はクイックリターンミラーより反射された光路に配置されたファインダースクリーン、８はペンタプリズム、９はファインダー、Ｅは観察者の眼（アイポイント）である。受光面４は、撮像素子として小型のＣＣＤまたはＣ−ＭＯＳ等の受光面として、デジタル一眼レフカメラへの適用が可能である。このような構成の一眼レフレックスカメラ１の撮影レンズ２を構成する光学系として、例えば上記実施例１〜３に示した本発明の結像光学系が用いられる。
FIG. 7 is a cross-sectional view of a single-lens reflex camera used as a photographing lens as an interchangeable lens apparatus provided with the imaging optical system of the present invention. In FIG. 7,
以上説明したように、本発明の結像光学系及びそれを備えた交換レンズ装置は、特許請求の範囲に記載された発明の他に次のような特徴を備えている。 As described above, the imaging optical system of the present invention and the interchangeable lens apparatus including the same have the following characteristics in addition to the invention described in the claims.
（付記項１）物体側から順に、正の屈折力を持つ前群と、明るさ絞りと、正の屈折力を持つ後群とからなり、前記後群が、物体側から順に、負レンズ成分と、第１の正レンズ成分と、第２の正レンズ成分を有し、次の条件式(1)，(2)を満足することを特徴とする結像光学系。
−４．０＜ｆＲ１２Ａ／ｆ＜−０．５ ・・・(1)
０．７＜ｆｂ／ｆ＜１．５ ・・・(2)
ただし、ｆは前記結像光学系全系の焦点距離、ｆＲ１２Ａは前記後群の負レンズ成分と該負レンズ成分の像側に位置する正レンズ成分とに挟まれる空気レンズの焦点距離、ｆｂは前記後群における最も像側のレンズの射出面から焦点までの光軸上での空気換算距離、である。
また、ここでのレンズ成分は、いずれも、光軸上において、各レンズ成分における最も物体側の面と最も像側の面のみが空気と接し、それらの面の間が空気と接しない、単レンズ又は接合レンズを意味する。
(Additional Item 1) In order from the object side, the front group has a positive refractive power, an aperture stop, and a rear group having a positive refractive power, and the rear group is a negative lens component in order from the object side. And an imaging optical system characterized by having the first positive lens component and the second positive lens component and satisfying the following conditional expressions (1) and (2):
-4.0 <fR12A / f <-0.5 (1)
0.7 <fb / f <1.5 (2)
Where f is the focal length of the entire imaging optical system, fR12A is the focal length of the air lens sandwiched between the negative lens component of the rear group and the positive lens component located on the image side of the negative lens component, and fb is This is the air equivalent distance on the optical axis from the exit surface to the focal point of the most image side lens in the rear group.
In addition, all the lens components here are on the optical axis, only the most object-side surface and the most image-side surface of each lens component are in contact with air, and those surfaces are not in contact with air. It means a lens or a cemented lens.
（付記項２）前記前群が、前記明るさ絞り側に向けた凹面を有する、該前群における最も像側のレンズ成分と、該前群における最も像側のレンズ成分よりも物体側に配置された正レンズ成分を有し、前記後群の前記負レンズ成分が、前記明るさ絞り側に凹面を向けていることを特徴とする付記項１に記載の結像光学系。
(Additional Item 2) The front group has a concave surface directed toward the brightness stop side, and is disposed closer to the object side than the most image side lens component in the front group and the most image side lens component in the front group. 2. The imaging optical system according to
（付記項３）物体側から順に、正の屈折力を持つ前群と、明るさ絞りと、正の屈折力を持つ後群とからなり、前記前群が、像側から順に、前記明るさ絞り側に向けた凹面を有する正メニスカスレンズ成分と、負レンズ成分と、正レンズ成分を有し、前記後群が、物体側から順に、前記明るさ絞り側に向けた凹面を有する負レンズ成分と、第１の正レンズ成分と、第２の正レンズ成分を有し、次の条件式(1)を満足することを特徴とする結像光学系。
−４．０＜ｆＲ１２Ａ／ｆ＜−０．５ ・・・(1)
ただし、ｆは前記結像光学系全系の焦点距離、ｆＲ１２Ａは前記後群の負レンズ成分と該負レンズ成分の像側に位置する正レンズ成分とに挟まれる空気レンズの焦点距離、である。
また、ここでのレンズ成分は、いずれも、光軸上において、各レンズ成分における最も物体側の面と最も像側の面のみが空気と接し、それらの面の間が空気と接しない、単レンズ又は接合レンズを意味する。
(Additional Item 3) In order from the object side, the front group has a positive refractive power, an aperture stop, and a rear group having a positive refractive power. The front group has the brightness in order from the image side. A negative meniscus lens component having a concave surface directed toward the aperture side, a negative lens component, and a positive lens component, and the rear group having a concave surface directed toward the brightness aperture side in order from the object side And an imaging optical system characterized by having the first positive lens component and the second positive lens component and satisfying the following conditional expression (1):
-4.0 <fR12A / f <-0.5 (1)
Where f is the focal length of the entire imaging optical system, and fR12A is the focal length of the air lens sandwiched between the negative lens component of the rear group and the positive lens component located on the image side of the negative lens component. .
In addition, all the lens components here are on the optical axis, only the most object-side surface and the most image-side surface of each lens component are in contact with air, and those surfaces are not in contact with air. It means a lens or a cemented lens.
（付記項４）前記前群の焦点距離をｆＦＧとしたとき、次の条件式(3)を満足することを特徴とする付記項１〜３のいずれかに記載の結像光学系。
２．２＜ｆＦＧ／ｆ＜４０．０ ・・・(3)
(Additional Item 4) The imaging optical system according to any one of
2.2 <fFG / f <40.0 (3)
（付記項５）前記後群の負レンズ成分の像側の面の近軸曲率半径をｒＡＦ、該負レンズ成分の像側に位置する正レンズ成分の物体側の面の近軸曲率半径をｒＡＲとしたとき、次の条件式(4)を満足することを特徴とする付記項１〜４のいずれかに記載の結像光学系。
−０．８＜（ｒＡＦ＋ｒＡＲ）／（ｒＡＦ−ｒＡＲ）＜２．５・・・(4)
(Additional Item 5) The paraxial radius of curvature of the image side surface of the negative lens component in the rear group is rAF, and the paraxial radius of curvature of the object side surface of the positive lens component located on the image side of the negative lens component is rAR. The imaging optical system according to any one of
−0.8 <(rAF + rAR) / (rAF−rAR) <2.5 (4)
（付記項６）前記結像レンズの各レンズ間隔の総和をΣｄＡ、前記明るさ絞りを挟む空気レンズの間隔をｄＳとしたとき、次の条件式(5)を満足することを特徴とする付記項１〜５のいずれかに記載の結像光学系。
０．６０＜ｄＳ／ΣｄＡ ・・・(5)
(Additional Item 6) The following conditional expression (5) is satisfied, where ΣdA is the sum of the intervals between the lenses of the imaging lens and dS is the interval between the air lenses that sandwich the aperture stop.
0.60 <dS / ΣdA (5)
（付記項７）前記前群が、物体側から順に、物体側の面の曲率の絶対値が像側の面の曲率の絶対値よりも大きい正レンズ成分と、物体側に凸面を向けた負メニスカスレンズ成分と、物体側に凸面を向けた正メニスカスレンズ成分とで構成され、前記後群が、物体側から順に、物体側の面の曲率の絶対値が像側の面の曲率の絶対値よりも大きい負レンズ成分と、像側に凸面を向けた正メニスカスレンズ成分と、像側の面の曲率の絶対値が物体側の面の曲率の絶対値よりも大きい正レンズ成分とで構成されることを特徴とする付記項１〜６のいずれかに記載の結像光学系。
(Additional Item 7) The front group includes, in order from the object side, a positive lens component in which the absolute value of the curvature of the object side surface is larger than the absolute value of the curvature of the image side surface, and a negative lens with a convex surface facing the object side. Consists of a meniscus lens component and a positive meniscus lens component with a convex surface facing the object side, and the rear group is, in order from the object side, the absolute value of the curvature of the object side surface is the absolute value of the curvature of the image side surface Negative lens component, a positive meniscus lens component having a convex surface toward the image side, and a positive lens component in which the absolute value of the curvature of the image side surface is greater than the absolute value of the curvature of the object side surface. The imaging optical system according to any one of
（付記項８）前記前群における最も像側のレンズ成分が正の屈折力を有し、前記前群の入射面から前記前群における最も像側のレンズ成分の直前のレンズ成分までが負の屈折力を持ち、前記前群における最も像側のレンズ成分とその直前のレンズ成分との空気間隔をｄＡ２としたとき、次の条件式(6)を満足することを特徴とする付記項１〜７のいずれかに記載の結像光学系。
０．０３５＜ｄＡ２／ｆ＜０．１ ・・・(6)
(Additional Item 8) The lens component closest to the image side in the front group has a positive refractive power, and negative from the entrance surface of the front group to the lens component immediately before the lens component closest to the image side in the front group.
0.035 <dA2 / f <0.1 (6)
（付記項９）前記後群の第１の正レンズ成分の焦点距離をｆＲＰ１、前記後群の第２の正レンズ成分の焦点距離をｆＲＰ２としたとき、次の条件式(7)を満足することを特徴とする付記項１〜８のいずれかに記載の結像光学系。
０．８＜ｆＲＰ１／ｆＲＰ２＜２．０ ・・・(7)
(Supplementary Item 9) When the focal length of the first positive lens component in the rear group is fRP1, and the focal length of the second positive lens component in the rear group is fRP2, the following conditional expression (7) is satisfied. The imaging optical system according to any one of
0.8 <fRP1 / fRP2 <2.0 (7)
（付記項１０）前記前群が、該前群において最も物体側に配置された正レンズと、その正レンズの像側に配置された、正レンズと負レンズを有することを特徴とする付記項１〜９のいずれかに記載の結像光学系。 (Supplementary Item 10) The supplementary item, wherein the front group includes a positive lens disposed closest to the object side in the front group, and a positive lens and a negative lens disposed on the image side of the positive lens. The imaging optical system according to any one of 1 to 9.
（付記項１１）前記前群が、物体側から順に、正レンズと、負レンズと、正レンズの３枚のレンズからなることを特徴とする付記項１〜１０のいずれかに記載の結像光学系。
(Additional Item 11) The imaging according to any one of
（付記項１２）無限遠合焦状態から近距離合焦を行う際に前記前群と前記後群との間隔が変化することを特徴とする付記項１〜１１のいずれかに記載の結像光学系。
(Additional Item 12) The imaging according to any one of
（付記項１３）前記後群のレンズが、全て単レンズで構成されていることを特徴とする付記項１〜１２のいずれかに記載の結像光学系。
(Additional Item 13) The imaging optical system according to any one of
（付記項１４）前記前群のレンズが、全て単レンズで構成されていることを特徴とする付記項１〜１３のいずれかに記載の結像光学系。
(Additional Item 14) The imaging optical system according to any one of
（付記項１５）付記項１〜１４のいずれかに記載の結像光学系と、該結像光学系をカメラ本体に取り付け可能とするマウント部を備えたことを特徴とする交換レンズ装置。
(Additional Item 15) An interchangeable lens apparatus comprising: the imaging optical system according to any one of
（付記項１６）物体側から順に、正の屈折力を持つ前群と、明るさ絞りと、正の屈折力を持つ後群とからなり、前記前群が、像側から順に、前記明るさ絞り側に向けた凹面を有する正メニスカスレンズ成分と、負レンズ成分と、正レンズ成分を有し、前記後群が、物体側から順に、前記明るさ絞り側に向けた凹面を有する負レンズ成分と、正レンズ成分と、正レンズ成分を有し、次の条件式(2-1)を満足することを特徴とする結像光学系。
０．９５＜ｆｂ／ｆ＜１．５ ・・・(2-1)
ただし、ｆは結像光学系全系の焦点距離、ｆｂは後群における最も像側レンズの射出面から焦点までの光軸上での空気換算距離、である。
また、ここでのレンズ成分は、いずれも、光軸上において、各レンズ成分における最も物体側の面と最も像側の面のみが空気と接し、それらの面の間が空気と接しない、単レンズ又は接合レンズを意味する。
(Additional Item 16) In order from the object side, the front group has a positive refractive power, an aperture stop, and a rear group having a positive refractive power. The front group has the brightness in order from the image side. A negative meniscus lens component having a concave surface directed toward the aperture side, a negative lens component, and a positive lens component, and the rear group having a concave surface directed toward the brightness aperture side in order from the object side And an imaging optical system having a positive lens component and a positive lens component and satisfying the following conditional expression (2-1):
0.95 <fb / f <1.5 (2-1)
Here, f is the focal length of the entire imaging optical system, and fb is the air equivalent distance on the optical axis from the exit surface of the image side lens to the focal point in the rear group.
In addition, all the lens components here are on the optical axis, only the most object-side surface and the most image-side surface of each lens component are in contact with air, and those surfaces are not in contact with air. It means a lens or a cemented lens.
本発明の結像光学系及びそれを備えたレンズ交換装置は、ＣＣＤ、Ｃ−ＭＯＳ等、光学像を電気信号に変換する電子撮像素子を用いたデジタル一眼レフカメラを使用する技術分野において有用である。 INDUSTRIAL APPLICABILITY The imaging optical system of the present invention and a lens exchange device including the imaging optical system are useful in a technical field that uses a digital single-lens reflex camera using an electronic image sensor that converts an optical image into an electrical signal, such as a CCD or C-MOS. is there.
Ｅ 観察者の眼
Ｇ１ 前群
Ｇ２ 後群
ＩＭ 結像面
Ｌ１１ 物体側に凸面を向けた正メニスカスレンズ
Ｌ１２ 物体側に凸面を向けた負メニスカスレンズ
Ｌ１３ 物体側に凸面を向けた正メニスカスレンズ
Ｌ２１ 物体側が凹面で像側が平面の平凹レンズ
Ｌ２１’ 両凹レンズ
Ｌ２２ 物体側に凹面を向けた正メニスカスレンズ
Ｌ２３ 両凸レンズ
Ｓ 明るさ絞り
１ 一眼レフレックスカメラ
２ 撮影レンズ
３ 一眼レフレックスカメラ
４ 受光面
５ クイックリターンミラー
６ 撮影レンズ２の光路
７ ファインダースクリーン
８ ペンタプリズム
９ ファインダー
E Eye of an observer G1 Front group G2 Rear group IM Imaging plane L11 Positive meniscus lens L12 having a convex surface facing the object side Negative meniscus lens L13 having a convex surface facing the object side Positive meniscus lens L21 having a convex surface facing the object side Plano-concave lens L21 ′ having a concave surface and a flat image side Bi-concave lens L22 Positive meniscus lens L23 having a concave surface facing the object side Biconvex lens
Claims (3)
前記後群が、物体側から順に、負レンズ成分と、第１の正レンズ成分と、第２の正レンズ成分を有し、
次の条件式(1)，(2)を満足することを特徴とする結像光学系。
−４．０＜ｆＲ１２Ａ／ｆ＜−０．５ ・・・(1)
０．７＜ｆｂ／ｆ＜１．５ ・・・(2)
ただし、
ｆは前記結像光学系全系の焦点距離、
ｆＲ１２Ａは前記後群の負レンズ成分と該負レンズ成分の像側に位置する正レンズ成分とに挟まれる空気レンズの焦点距離、
ｆｂは前記後群における最も像側のレンズの射出面から焦点までの光軸上での空気換算距離、
である。
また、ここでのレンズ成分は、いずれも、光軸上において、各レンズ成分における最も物体側の面と最も像側の面のみが空気と接し、それらの面の間が空気と接しない、単レンズ又は接合レンズを意味する。 In order from the object side, it consists of a front group with positive refractive power, an aperture stop, and a rear group with positive refractive power,
The rear group includes, in order from the object side, a negative lens component, a first positive lens component, and a second positive lens component;
An imaging optical system characterized by satisfying the following conditional expressions (1) and (2).
-4.0 <fR12A / f <-0.5 (1)
0.7 <fb / f <1.5 (2)
However,
f is the focal length of the entire imaging optical system,
fR12A is the focal length of the air lens sandwiched between the negative lens component of the rear group and the positive lens component located on the image side of the negative lens component,
fb is an air-converted distance on the optical axis from the exit surface to the focal point of the most image-side lens in the rear group,
It is.
In addition, all the lens components here are on the optical axis, only the most object-side surface and the most image-side surface of each lens component are in contact with air, and those surfaces are not in contact with air. It means a lens or a cemented lens.
前記後群の前記負レンズ成分が、前記明るさ絞り側に凹面を向けていることを特徴とする請求項１に記載の結像光学系。 The front group has a concave surface directed toward the aperture stop side, and the most image side lens component in the front group, and a positive lens component arranged closer to the object side than the most image side lens component in the front group Have
The imaging optical system according to claim 1, wherein the negative lens component of the rear group has a concave surface directed toward the brightness stop.
前記前群が、像側から順に、前記明るさ絞り側に向けた凹面を有する正メニスカスレンズ成分と、負レンズ成分と、正レンズ成分を有し、
前記後群が、物体側から順に、前記明るさ絞り側に向けた凹面を有する負レンズ成分と、第１の正レンズ成分と、第２の正レンズ成分を有し、
次の条件式(1)を満足することを特徴とする結像光学系。
−４．０＜ｆＲ１２Ａ／ｆ＜−０．５ ・・・(1)
ただし、
ｆは前記結像光学系全系の焦点距離、
ｆＲ１２Ａは前記後群の負レンズ成分と該負レンズ成分の像側に位置する正レンズ成分とに挟まれる空気レンズの焦点距離、
である。
また、ここでのレンズ成分は、いずれも、光軸上において、各レンズ成分における最も物体側の面と最も像側の面のみが空気と接し、それらの面の間が空気と接しない、単レンズ又は接合レンズを意味する。 In order from the object side, it consists of a front group with positive refractive power, an aperture stop, and a rear group with positive refractive power,
The front group, in order from the image side, has a positive meniscus lens component having a concave surface directed toward the aperture stop side, a negative lens component, and a positive lens component;
The rear group has, in order from the object side, a negative lens component having a concave surface directed toward the aperture stop side, a first positive lens component, and a second positive lens component;
An imaging optical system satisfying the following conditional expression (1):
-4.0 <fR12A / f <-0.5 (1)
However,
f is the focal length of the entire imaging optical system,
fR12A is the focal length of the air lens sandwiched between the negative lens component of the rear group and the positive lens component located on the image side of the negative lens component,
It is.
In addition, all the lens components here are on the optical axis, only the most object-side surface and the most image-side surface of each lens component are in contact with air, and those surfaces are not in contact with air. It means a lens or a cemented lens.
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