JP2015118186A - Optical system, optical instrument, and method for manufacturing optical system - Google Patents

Optical system, optical instrument, and method for manufacturing optical system Download PDF

Info

Publication number
JP2015118186A
JP2015118186A JP2013260469A JP2013260469A JP2015118186A JP 2015118186 A JP2015118186 A JP 2015118186A JP 2013260469 A JP2013260469 A JP 2013260469A JP 2013260469 A JP2013260469 A JP 2013260469A JP 2015118186 A JP2015118186 A JP 2015118186A
Authority
JP
Japan
Prior art keywords
lens
optical
refractive power
positive
conditional expression
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2013260469A
Other languages
Japanese (ja)
Inventor
壮基 原田
Masaki Harada
壮基 原田
幸介 町田
Kosuke Machida
幸介 町田
Original Assignee
株式会社ニコン
Nikon Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 株式会社ニコン, Nikon Corp filed Critical 株式会社ニコン
Priority to JP2013260469A priority Critical patent/JP2015118186A/en
Publication of JP2015118186A publication Critical patent/JP2015118186A/en
Pending legal-status Critical Current

Links

Images

Abstract

PROBLEM TO BE SOLVED: To provide an optical system having a good optical performance, an optical apparatus, and a method for manufacturing the optical system. SOLUTION: A first lens group G1 and a second lens group G2 having a positive refractive power arranged in order from the object side, and the first lens group G1 has a negative lens and a positive lens. When focusing from an infinitely distant object to a close object, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I, the second lens group G2 moves, and the first lens group G1. And the second lens group G2 change, and the following conditional expressions (1) to (3) are satisfied. 0.50 <νn / νp <1.60 (1) 5.00 <| f1 | / f <30.00 (2) 1.15 <f2 / f <1.70 (3) Figure 1

Description

  The present invention relates to an optical system, an optical apparatus, and a method for manufacturing the optical system.

  Conventionally, wide-angle lenses suitable for photographic cameras, electronic still cameras, video cameras, and the like have been proposed (see, for example, Patent Document 1).

JP 2009-109723 A

  However, further improvement in optical performance is required compared to conventional wide-angle lenses.

  The present invention has been made in view of such problems, and an object thereof is to provide an optical system, an optical apparatus, and an optical system manufacturing method having good optical performance.

  In order to achieve such an object, an optical system according to the present invention includes a first lens group and a second lens group having a positive refractive power, which are arranged in order from the object side, and the first lens group. Has a negative lens and a positive lens, and the first lens group is fixed in the optical axis direction with respect to the image plane when focusing from an object at infinity to a short distance object, and the second lens The group moves, the distance between the first lens group and the second lens group changes, and the following conditional expression is satisfied.

0.50 <νn / νp <1.60
5.00 <| f1 | / f <30.00
1.15 <f2 / f <1.70
However,
ν n: Abbe number based on the d-line of the glass material of the lens having the strongest negative refractive power in the first lens group,
νp: Abbe number based on the d-line of the glass material of the lens having the strongest positive refractive power in the first lens group,
f1: the focal length of the first lens group,
f2: focal length of the second lens group,
f: The focal length of the entire system in the infinitely focused state.

  In the optical system according to the present invention, it is preferable that the first lens group includes a cemented lens.

  In the optical system according to the present invention, among the cemented lenses included in the first lens group, the cemented lens positioned closest to the object side of the lens having the most positive refractive power includes a negative lens and a positive lens. Therefore, it is preferable that the following conditional expression is satisfied.

0.20 <ν11 / ν12 <1.00
However,
ν11: Abbe number based on the d-line of the glass material of the positive lens constituting the cemented lens closest to the object side of the lens having the strongest positive refractive power in the first lens group,
ν12: Abbe number based on the d-line of the glass material of the negative lens constituting the cemented lens closest to the object side of the lens having the strongest positive refractive power in the first lens group.

  In the optical system according to the present invention, the second lens group includes an aperture stop, a lens having the strongest negative refracting power in the lens group located on the object side of the aperture stop, and an object side immediately before the negative lens on the object side. It is preferable that the following conditional expression is satisfied.

0.60 <n21 / n22 <1.00
However,
n21: The refractive index of the lens material having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop in the second lens group with respect to the d-line of the glass material of the positive lens located immediately before the object side ,
n22: a refractive index with respect to d-line of the glass material of the lens having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop in the second lens group.

  In the optical system according to the present invention, the second lens group includes an aperture stop, a lens having the strongest negative refracting power in the lens group located on the object side of the aperture stop, and an object side immediately before the negative lens on the object side. It is preferable that the following conditional expression is satisfied.

1.40 <ν21 / ν22 <2.80
However,
ν 21: Based on the d-line of the glass material of the positive lens located immediately before the object side of the lens unit having the strongest negative refractive power in the lens group located on the object side of the aperture stop in the second lens group Abbe number,
ν22: Abbe number based on the d-line of the glass material of the lens having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop in the second lens group.

  In the optical system according to the present invention, the second lens group includes an aperture stop, a front group located closer to the object side than the aperture stop, and a rear group located closer to the image side than the aperture stop, When focusing from an object at infinity to an object at a short distance, it is preferable to move each group while maintaining or changing the distance between the front group and the rear group.

  In the optical system according to the present invention, it is preferable that the second lens group has at least one aspheric lens.

  An optical apparatus according to the present invention is equipped with any of the optical systems described above.

  The method for manufacturing an optical system according to the present invention is a method for manufacturing an optical system having a first lens group and a second lens group having positive refractive power arranged in order from the object side, wherein the first lens The group includes a negative lens and a positive lens, and the first lens group is fixed in the optical axis direction with respect to the image plane when focusing from an object at infinity to an object at a short distance. Each lens is arranged in the lens barrel so that the lens group moves, the distance between the first lens group and the second lens group changes, and the following conditional expression is satisfied.

0.50 <νn / νp <1.60
5.00 <| f1 | / f <30.00
1.15 <f2 / f <1.70
However,
ν n: Abbe number based on the d-line of the glass material of the lens having the strongest negative refractive power in the first lens group,
νp: Abbe number based on the d-line of the glass material of the lens having the strongest positive refractive power in the first lens group,
f1: the focal length of the first lens group,
f2: focal length of the second lens group,
f: The focal length of the entire system in the infinitely focused state.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the optical system, optical apparatus, and optical system which have favorable optical performance can be provided.

It is sectional drawing which shows the lens structure of the optical system which concerns on 1st Example. FIG. 4 is a diagram illustrating various aberrations of the optical system according to Example 1, where (a) is an infinitely focused state (imaging magnification β = 0.00), and (b) is a short-distance focused state (imaging magnification β = −1 / 30). ) Respectively. It is sectional drawing which shows the lens structure of the optical system which concerns on 2nd Example. FIG. 6 is a diagram illustrating various aberrations of the optical system according to Example 2, wherein (a) is in an infinite focus state (shooting magnification β = 0.00), and (b) is a close focus state (shooting magnification β = −1 / 30). ) Respectively. It is sectional drawing which shows the lens structure of the optical system which concerns on 3rd Example. FIG. 6 is a diagram illustrating various aberrations of the optical system according to Example 3, wherein (a) is in an infinite focus state (shooting magnification β = 0.00), and (b) is a short distance focus state (shooting magnification β = −1 / 30). ) Respectively. It is sectional drawing which shows the lens structure of the optical system which concerns on 4th Example. FIG. 10 is a diagram illustrating various aberrations of the optical system according to Example 4, wherein (a) is in the infinite focus state (shooting magnification β = 0.00), and (b) is the close focus state (shooting magnification β = −1 / 30). ) Respectively. It is sectional drawing which shows the lens structure of the optical system which concerns on 5th Example. FIG. 9A is a diagram illustrating various aberrations of the optical system according to Example 5, wherein (a) is in an infinite focus state (shooting magnification β = 0.00), and (b) is a short distance focus state (shooting magnification β = −1 / 30). ) Respectively. It is sectional drawing which shows the lens structure of the optical system which concerns on 6th Example. FIG. 11A is a diagram illustrating various aberrations of the optical system according to Example 6, where (a) is in an infinite focus state (shooting magnification β = 0.00), and (b) is a close focus state (shooting magnification β = −1 / 30). ) Respectively. It is sectional drawing which shows the lens structure of the optical system which concerns on 7th Example. FIG. 9A is a diagram illustrating various aberrations of the optical system according to Example 7, wherein (a) is in an infinite focus state (shooting magnification β = 0.00), and (b) is a short distance focus state (shooting magnification β = −1 / 30). ) Respectively. It is sectional drawing which shows the lens structure of the optical system which concerns on an 8th Example. FIG. 10 is a diagram illustrating various aberrations of the optical system according to Example 8, where (a) is in an infinite focus state (shooting magnification β = 0.00), and (b) is a close focus state (shooting magnification β = −1 / 30). ) Respectively. It is sectional drawing which shows the lens structure of the optical system which concerns on 9th Example. FIG. 10 is a diagram illustrating various aberrations of the optical system according to Example 9, where (a) is in an infinite focus state (shooting magnification β = 0.00), and (b) is a close focus state (shooting magnification β = −1 / 30). ) Respectively. It is a figure which shows the structure of the camera carrying the optical system which concerns on this embodiment. It is a flowchart which shows the manufacturing method of the optical system which concerns on this embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. As shown in FIG. 1, the optical system WL according to the present embodiment includes a first lens group G1 and a second lens group G2 having positive refractive power, which are arranged in order from the object side. The group G1 includes a negative lens and a positive lens, and the first lens group G1 is fixed in the optical axis direction with respect to the image plane I during focusing from an object at infinity to an object at a short distance. Then, the second lens group G2 moves and the distance between the first lens group G1 and the second lens group G2 changes, and the following conditional expressions (1) to (3) are satisfied.

0.50 <νn / νp <1.60 (1)
5.00 <| f1 | / f <30.00 (2)
1.15 <f2 / f <1.70 (3)
However,
νn: Abbe number based on the d-line of the glass material of the lens having the strongest negative refractive power in the first lens group G1,
νp: Abbe number based on the d-line of the glass material of the lens having the strongest positive refractive power in the first lens group G1,
f1: Focal length of the first lens group G1
f2: focal length of the second lens group G2,
f: The focal length of the entire system in the infinitely focused state.

  As described above, the first lens group G1 has the first lens group G1 and the second lens group G2 having a positive refractive power, and the first lens group G1 is fixed when focusing from an object at infinity to an object at a short distance. With the configuration in which the second lens group G2 moves, the lens barrel can be reduced in size and aberration variation (for example, spherical aberration) due to focusing can be corrected well.

  Conditional expression (1) defines the ratio between the Abbe number of the lens having the strongest negative refractive power in the first lens group G1 and the Abbe number of the lens having the strongest positive refractive power in the first lens group G1. To do. By satisfying conditional expression (1), chromatic aberration can be corrected satisfactorily.

  When the corresponding value of the conditional expression (1) exceeds the upper limit value, the Abbe number of the lens having a positive refractive power becomes too small as compared with the Abbe number of a lens having a negative refractive power, so that chromatic aberration correction becomes excessive. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 1.45.

  If the corresponding value of the conditional expression (1) is less than the lower limit value, the Abbe number of the lens having a positive refractive power becomes too large compared to the Abbe number of a lens having a negative refractive power, so that chromatic aberration correction is insufficient. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit value of conditional expression (1) to 0.65.

  Conditional expression (2) defines the ratio between the focal length of the first lens group G1 and the focal length of the entire system in the infinitely focused state. Satisfying conditional expression (2) makes it possible to achieve good optical performance.

  When the corresponding value of the conditional expression (2) exceeds the upper limit value, the refractive power of the first lens group G1 becomes weak, and it becomes difficult to correct field curvature and coma. In order to secure the effect of the present embodiment, it is preferable to set the upper limit value of conditional expression (2) to 25.00.

  If the corresponding value of conditional expression (2) is below the lower limit value, the refractive power of the first lens group G1 becomes strong, and it becomes difficult to correct field curvature and coma. In order to secure the effect of the present embodiment, it is preferable to set the lower limit value of conditional expression (2) to 8.00.

  Conditional expression (3) defines the ratio between the focal length of the second lens group G2 and the focal length of the entire system in the infinitely focused state. Satisfying conditional expression (3) makes it possible to achieve good optical performance.

  When the corresponding value of the conditional expression (3) exceeds the upper limit value, the refractive power of the second lens group G2 becomes weak and the entire length increases. In addition, it becomes difficult to correct spherical aberration and coma. In order to secure the effect of the present embodiment, it is preferable to set the upper limit value of conditional expression (3) to 1.55.

  When the corresponding value of conditional expression (3) is below the lower limit, the refractive power of the second lens group G2 becomes strong, making it difficult to secure the back focus, and in addition, it becomes difficult to correct field curvature and coma. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to 1.30.

  In the optical system WL according to the present embodiment, the first lens group G1 preferably includes a cemented lens. With this configuration, both axial chromatic aberration and lateral chromatic aberration can be corrected well.

  In the optical system WL according to the present embodiment, among the cemented lenses included in the first lens group G1, the cemented lens closest to the object side of the lens having the strongest positive refractive power is a negative lens, a positive lens, It is preferable that the following conditional expression (4) is satisfied.

0.20 <ν11 / ν12 <1.00 (4)
However,
ν11: Abbe number based on the d-line of the glass material of the positive lens constituting the cemented lens closest to the object side of the lens having the strongest positive refractive power in the first lens group G1,
ν12: Abbe number based on the d-line of the glass material of the negative lens constituting the cemented lens closest to the object side of the lens having the strongest positive refractive power in the first lens group G1.

  Conditional expression (4) indicates that the Abbe number of the positive lens and the Abbe number of the negative lens constituting the cemented lens located closest to the object side of the lens having the strongest positive refractive power in the first lens group G1. (In FIG. 1, the positive lens L12 and the negative lens L13 constituting the cemented lens closest to the object side in the first lens group G1 are applicable). By satisfying conditional expression (4), chromatic aberration can be corrected satisfactorily.

  If the corresponding value of the conditional expression (4) exceeds the upper limit value, the Abbe number of the positive lens constituting the cemented lens in the first lens group G1 becomes too larger than the Abbe number of the negative lens. Is lacking. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 0.80.

  When the corresponding value of the conditional expression (4) is less than the lower limit value, the Abbe number of the positive lens constituting the cemented lens in the first lens group G1 is too small than the Abbe number of the negative lens. Becomes excessive. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 0.40.

  In the optical system WL according to the present embodiment, the second lens group G2 includes an aperture stop S, a lens having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop S, and the negative lens. It is preferable to have a positive lens located immediately before the object side and satisfy the following conditional expression (5).

0.60 <n21 / n22 <1.00 (5)
However,
n21: the refractive index of the lens material having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop S in the second lens group G2 with respect to the d-line of the glass material of the positive lens located immediately before the object side;
n22: Refractive index with respect to d-line of the glass material of the lens having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop S in the second lens group G2.

  Conditional expression (5) represents the refractive index of the positive lens located immediately before the object side of the lens having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop S in the second lens group G2. Defines the ratio with the refractive index of the lens having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop S in the second lens group G2 (in FIG. 1, the second lens A positive lens L22 and a negative lens L23 constituting a cemented lens positioned on the object side of the aperture stop S in the group G2). Satisfying conditional expression (5) makes it possible to achieve good optical performance.

  When the corresponding value of the conditional expression (5) exceeds the upper limit value, the refractive index of the positive lens becomes too larger than the refractive index of the negative lens, so that correction of spherical aberration at the cemented surface is insufficient. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 0.97.

  If the corresponding value of the conditional expression (5) is less than the lower limit value, the refractive index of the positive lens becomes too smaller than the refractive index of the negative lens, so that the correction of spherical aberration at the cemented surface becomes excessive. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 0.80.

  In the optical system WL according to the present embodiment, the second lens group G2 includes an aperture stop S, a lens having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop S, and the negative lens. It is preferable to have a positive lens positioned immediately before the object side and satisfy the following conditional expression (6).

1.40 <ν21 / ν22 <2.80 (6)
However,
ν21: The d-line of the glass material of the positive lens located immediately before the object side of the lens having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop S in the second lens group G2 Abbe number,
ν22: Abbe number based on the d-line of the glass material of the lens having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop S in the second lens group G2.

  Conditional expression (6) is the Abbe number of the positive lens located immediately before the object side of the lens having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop S in the second lens group G2. In the second lens group G2, the ratio to the Abbe number of the lens having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop S is defined (in FIG. 1, the second lens A positive lens L22 and a negative lens L23 constituting a cemented lens positioned on the object side of the aperture stop S in the group G2). Satisfying conditional expression (6) makes it possible to achieve good optical performance.

  If the corresponding value of the conditional expression (6) exceeds the upper limit value, the Abbe number of the positive lens becomes too larger than the Abbe number of the negative lens, so that the correction of chromatic aberration becomes excessive. In order to secure the effect of the present embodiment, it is preferable to set the upper limit value of conditional expression (6) to 2.50.

  When the corresponding value of conditional expression (6) is below the lower limit value, the Abbe number of the positive lens becomes too smaller than the Abbe number of the negative lens, so that correction of chromatic aberration is insufficient. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (6) to 1.60.

  In the optical system WL according to the present embodiment, the second lens group G2 includes an aperture stop S, a front group G2a positioned on the object side of the aperture stop S, and a rear group G2b positioned on the image side of the aperture stop S. When focusing from an object at infinity to an object at a short distance, it is preferable to move each group while maintaining or changing the distance between the front group and the rear group. With this configuration, it is possible to satisfactorily correct aberration fluctuations (for example, coma aberration) due to focusing.

  In the optical system WL according to the present embodiment, the second lens group G2 preferably has at least one aspheric lens. With this configuration, various aberrations such as coma, spherical aberration, and curvature of field can be favorably corrected.

  According to the optical system WL according to the present embodiment having the above-described configuration, an optical system having good optical performance can be realized.

  Next, a camera (optical apparatus) including the above-described optical system WL will be described with reference to FIG. As shown in FIG. 19, the camera 1 is an interchangeable lens camera (so-called mirrorless camera) provided with the above-described optical system WL as a photographing lens 2. In this camera 1, light from an object (subject) (not shown) is collected by the taking lens 2, and on the imaging surface of the imaging unit 3 via an OLPF (Optical Low Pass Filter) not shown. A subject image is formed on the screen. Then, the subject image is photoelectrically converted by the photoelectric conversion element provided in the imaging unit 3 to generate an image of the subject. This image is displayed on an EVF (Electronic view finder) 4 provided in the camera 1. Thus, the photographer can observe the subject via the EVF 4. When the release button (not shown) is pressed by the photographer, the subject image generated by the imaging unit 3 is stored in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1.

  Here, the above-described optical system WL mounted on the camera 1 as the photographing lens 2 has good optical performance. Therefore, according to the camera 1, good optical performance can be realized. Even when the above-described optical system WL is mounted on a single-lens reflex camera having a quick return mirror and observing a subject with a finder optical system, the same effect as the camera 1 can be obtained. Further, even when the above-described optical system WL is mounted on a video camera, the same effects as the camera 1 can be obtained.

  Next, the method for manufacturing the above-described optical system WL will be outlined with reference to FIG. First, each lens is arranged in the lens barrel so as to have a first lens group G1 and a second lens group G2 having positive refractive power arranged in order from the object side (step ST10). At this time, the first lens group G1 has a negative lens and a positive lens (step ST20). At the time of focusing from an object at infinity to an object at a short distance, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I, the second lens group G2 moves, and the first lens group G1 and the first lens group G1 Each lens is arranged so that the distance from the second lens group G2 changes (step ST30). Each lens is arranged in the lens barrel so as to satisfy the following conditional expressions (1) to (3) (step ST40).

0.50 <νn / νp <1.60 (1)
5.00 <| f1 | / f <30.00 (2)
1.15 <f2 / f <1.70 (3)
However,
νn: Abbe number based on the d-line of the glass material of the lens having the strongest negative refractive power in the first lens group G1,
νp: Abbe number based on the d-line of the glass material of the lens having the strongest positive refractive power in the first lens group G1,
f1: Focal length of the first lens group G1
f2: focal length of the second lens group G2,
f: The focal length of the entire system in the infinitely focused state.

  As an example of the lens arrangement in the present embodiment, in the optical system WL shown in FIG. 1, as the first lens group G1, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, and a concave surface facing the object side. A cemented negative lens of a positive meniscus lens L12 and a biconcave negative lens L13, and a biconvex positive lens L14 are arranged in the lens barrel. As the second lens group G2 having positive refractive power, in order from the object side, a biconvex positive lens L21, a cemented negative lens of a biconvex positive lens L22 and a biconcave negative lens L23, and an aperture A diaphragm S, a cemented negative lens of a biconcave negative lens L24 and a biconvex positive lens L25, a biconvex positive lens L26, and a positive meniscus lens L27 having a concave surface facing the object side It is placed inside. These lenses are arranged so as to satisfy conditional expressions (1) to (3) (the corresponding value of conditional expression (1) is 1.053, the corresponding value of conditional expression (2) is 16.633, conditional expression) The corresponding value for (3) is 1.475).

  According to said manufacturing method, the optical system which has favorable optical performance can be manufactured.

  Each example according to the present embodiment will be described with reference to the drawings. Tables 1 to 9 are shown below, but these are tables of specifications in the first to ninth examples.

  In addition, each reference code with respect to FIG. 1 according to the first embodiment is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference code. Therefore, even if the same reference numerals as those in the drawings according to the other embodiments are given, they are not necessarily in the same configuration as the other embodiments.

  In each embodiment, d-line (wavelength 587.5620 nm) and g-line (wavelength 435.8350 nm) are selected as the calculation targets of the aberration characteristics.

  In [Lens Specifications] in the table, the surface number is the order of the optical surfaces from the object side along the light traveling direction, R is the radius of curvature of each optical surface, D is the next optical surface from each optical surface ( Or nd is the refractive index of the material of the optical member with respect to the d-line, and νd is the Abbe number based on the d-line of the material of the optical member. The object plane is the object plane, (variable) is the variable plane spacing, the curvature radius “∞” is the plane or aperture, (aperture S) is the aperture stop S, and the image plane is the image plane I. The description of the refractive index “1.00000” of air is omitted. When the optical surface is an aspherical surface, the surface number is marked with *, and the column of curvature radius R indicates the paraxial curvature radius.

In [Aspherical data] in the table, the shape of the aspherical surface shown in [Lens specifications] is shown by the following equation (a). X (y) is the distance along the optical axis direction from the tangential plane at the apex of the aspheric surface to the position on the aspheric surface at height y, r is the radius of curvature of the reference sphere (paraxial radius of curvature), and κ is Ai represents the i-th aspherical coefficient. “E-n” indicates “× 10 −n ”. For example, 1.234E-05 = 1.234 × 10 −5 .

X (y) = (y 2 / r) / {1+ (1-κ × y 2 / r 2 ) 1/2 } + A4y 4 + A6y 6 + A8y 8 + A10y 10 (a)

  In [Overall specifications] in the table, f is the focal length of the entire lens system, FNo is the F number, ω is the half angle of view (unit: °), Ymax is the maximum image height, and Bf is the final lens on the optical axis. The distance from the surface to the paraxial image plane, TL, indicates the total optical length (the distance from the lens frontmost surface to the lens final surface on the optical axis plus Bf).

  In [Variable interval data] in the table, the variable interval value Di in each of the infinite focus state (shooting magnification β = 0.00) and the short distance focus state (shooting magnification β = −1 / 30) is shown. Di represents a variable interval between the i-th surface and the (i + 1) -th surface. The distance from the object to the forefront of the lens is D0.

  In [Lens Group Data] in the table, G represents the group number, the first group surface represents the surface number of the most object side of each group, and the group focal length represents the focal length of each group.

  [Conditional expression] in the table indicates values corresponding to the conditional expressions (1) to (6).

  Hereinafter, in all the specification values, “mm” is generally used for the focal length, the radius of curvature, the surface interval, and other lengths, etc. unless otherwise specified, but the optical system is proportionally enlarged or reduced. However, the same optical performance can be obtained, and the present invention is not limited to this. Further, the unit is not limited to “mm”, and other appropriate units can be used.

  The description of the table so far is common to all the embodiments, and the description below is omitted.

(First embodiment)
A first embodiment will be described with reference to FIGS. 1 and 2 and Table 1. FIG. As shown in FIG. 1, the optical system WL (WL1) according to the first example includes a first lens group G1 having a positive refractive power and a second lens having a positive refractive power, which are arranged in order from the object side. And a group G2. The second lens group G2 includes a front group G2a having a positive refractive power, an aperture stop S, and a rear group G2b having a positive refractive power, which are arranged in order from the object side.

  The first lens group G1 includes a negative meniscus lens L11 having a convex surface directed toward the object side, a positive meniscus lens L12 having a concave surface directed toward the object side, and a biconcave negative lens L13 arranged in order from the object side. The lens includes a biconvex positive lens L14.

  The front group G2a of the second lens group G2 is composed of a biconvex positive lens L21 and a cemented negative lens of a biconvex positive lens L22 and a biconcave negative lens L23 arranged in order from the object side. .

  The rear group G2b of the second lens group G2 includes, in order from the object side, a cemented negative lens of a biconcave negative lens L24 and a biconvex positive lens L25, a biconvex positive lens L26, And a positive meniscus lens L27 having a concave surface on the side. The positive meniscus lens L27 includes an aspheric thin plastic resin layer on the object side lens surface.

  In the optical system WL1 according to the present embodiment, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I during focusing from a long distance object to a short distance object, and the second lens group G2 Are integrally moved to the object side.

  Table 1 below shows the values of each item in the first example. Surface numbers 1 to 21 in Table 1 correspond to the optical surfaces m1 to m21 shown in FIG.

(Table 1)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 226.5998 1.900 1.58913 61.22
2 26.3342 13.931
3 -8835.5536 2.725 1.78472 25.64
4 -139.1833 1.500 1.58913 61.22
5 50.3375 2.000
6 37.4060 10.330 1.62299 58.12
7 -74.8089 D7 (variable)
8 32.1428 4.462 1.80400 46.60
9 -571.0364 0.434
10 391.7521 3.425 1.59319 67.90
11 -41.6538 2.322 1.67270 32.18
12 30.4662 3.636
13 ∞ 8.575 (Aperture S)
14 -16.5791 1.100 1.64769 33.72
15 143.1682 2.537 1.69680 55.52
16 -101.1506 0.180
17 255.4058 5.844 1.77250 49.62
18 -25.5855 0.180
* 19 -124.4651 0.150 1.53610 41.21
20 -80.1581 2.534 1.71300 53.96
21 -44.4932 Bf
Image plane ∞

[Aspherical data]
19th surface κ = 1.0000
A4 = -1.39304E-05
A6 = -6.37142E-09
A8 = -3.21874E-11
A10 = 0.00000E + 00

[Overall specifications]
f 34.5
FNo 1.86
ω 32.68
Ymax 21.6
Bf 38.42
TL 115.40

[Variable interval data]
Variable interval infinity short distance D0 ∞ 1019.325
D7 9.215 8.063

[Lens group data]
Group number Group first surface Group focal length G1 1 574.104
G2 8 50.927

[Conditional expression]
Conditional expression (1) νn / νp = 1.053
Conditional expression (2) | f1 | /f=16.333
Conditional expression (3) f2 / f = 1.475
Conditional expression (4) n21 / n22 = 0.952
Conditional expression (5) ν21 / ν22 = 2.110
Conditional expression (6) ν11 / ν12 = 0.419

  From Table 1, it can be seen that the optical system WL1 according to the present example satisfies the conditional expressions (1) to (6).

  FIG. 2 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma aberration diagram and chromatic aberration diagram of magnification) of the optical system WL1 according to the first example, and (a) is infinite focus. The state (photographing magnification β = 0.00) and (b) show the close-in-focus state (photographing magnification β = −1 / 30).

  In each aberration diagram, FNO represents an F number, NA represents a numerical aperture, and Y represents an image height. d represents the aberration at the d-line, and g represents the aberration at the g-line. Those not described indicate aberrations at the d-line. In the spherical aberration diagram, the F number or numerical aperture corresponding to the maximum aperture is shown. In the astigmatism diagram and the distortion diagram, Y represents the maximum value of the image height. In the coma aberration diagram, Y indicates the value of each image height. In the graph showing astigmatism, a solid line indicates a sagittal image plane, and a broken line indicates a meridional image plane. In the coma aberration diagram, the solid line indicates the meridional coma. Hereinafter, also in the aberration diagrams of the respective examples, the same symbols as those of the present example are used.

  From the aberration diagrams shown in FIG. 2, it can be seen that the optical system WL1 according to the first example has various optical aberrations corrected and has good optical performance.

(Second embodiment)
The second embodiment will be described with reference to FIGS. 3 and 4 and Table 2. FIG. As shown in FIG. 3, the optical system WL (WL2) according to the second example includes a first lens group G1 having a positive refractive power and a second lens having a positive refractive power, which are arranged in order from the object side. And a group G2. The second lens group G2 includes a front group G2a having a positive refractive power, an aperture stop S, and a rear group G2b having a positive refractive power, which are arranged in order from the object side.

  The first lens group G1 includes a negative meniscus lens L11 having a convex surface directed toward the object side, a positive meniscus lens L12 having a concave surface directed toward the object side, and a biconcave negative lens L13 arranged in order from the object side. The lens includes a biconvex positive lens L14.

  The front group G2a of the second lens group G2 is composed of a biconvex positive lens L21 and a cemented negative lens of a biconvex positive lens L22 and a biconcave negative lens L23 arranged in order from the object side. .

  The rear group G2b of the second lens group G2 includes, in order from the object side, a cemented negative lens of a biconcave negative lens L24 and a biconvex positive lens L25, a biconvex positive lens L26, And a positive meniscus lens L27 having a concave surface on the side. The positive meniscus lens L27 includes an aspheric thin plastic resin layer on the object side lens surface.

  In the optical system WL2 according to the present embodiment, when focusing from a long distance object to a short distance object, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I, and the second lens group G2 Are integrally moved to the object side.

  Table 2 below shows the values of each item in the second embodiment. Surface numbers 1 to 21 in Table 2 correspond to the optical surfaces m1 to m21 shown in FIG.

(Table 2)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 252.7953 1.500 1.48749 70.41
2 26.5555 12.992
3 -480.3085 4.990 1.77250 49.61
4 -58.0470 1.500 1.49782 82.52
5 40.1063 0.200
6 31.1474 11.000 1.61800 63.37
7 -158.5305 D7 (variable)
8 31.7370 4.387 1.80400 46.57
9 -196.5666 0.392
10 2275.2314 2.598 1.48749 70.41
11 -49.7270 1.150 1.68893 31.07
12 28.7264 3.478
13 ∞ 7.191 (Aperture S)
14 -15.3838 1.150 1.62588 35.74
15 97.2875 3.084 1.72916 54.66
16 -67.6930 0.200
17 243.6076 5.958 1.75500 52.31
18 -25.5794 0.152
* 19 -84.0807 0.150 1.53610 41.21
20 -59.6448 2.616 1.69680 55.52
21 -37.3609 Bf
Image plane ∞

[Aspherical data]
19th surface κ = 1.0000
A4 = -1.52050E-05
A6 = -7.10240E-09
A8 = -2.84360E-11
A10 = 0.00000E + 00

[Overall specifications]
f 35.5
FNo 1.86
ω 32.02
Ymax 21.6
Bf 38.82
TL 115.02

[Variable interval data]
Variable interval infinity short distance D0 ∞ 1043.924
D7 11.514 10.329

[Lens group data]
Group number Group first surface Group focal length G1 1 437.831
G2 8 46.714

[Conditional expression]
Conditional expression (1) νn / νp = 1.302
Conditional expression (2) | f1 | /f=12.350
Conditional expression (3) f2 / f = 1.318
Conditional expression (4) n21 / n22 = 0.881
Conditional expression (5) ν21 / ν22 = 2.266
Conditional expression (6) ν11 / ν12 = 0.783

  From Table 2, it can be seen that the optical system WL2 according to the present example satisfies the conditional expressions (1) to (6).

  FIG. 4 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma aberration diagram and chromatic aberration diagram of magnification) of the optical system WL2 according to the second example, and (a) is infinite focus. The state (photographing magnification β = 0.00) and (b) show the close-in-focus state (photographing magnification β = −1 / 30).

  From the respective aberration diagrams shown in FIG. 4, it can be seen that the optical system WL2 according to the second example has favorable optical performance with various aberrations corrected well.

(Third embodiment)
A third embodiment will be described with reference to FIGS. 5 and 6 and Table 3. FIG. As shown in FIG. 5, the optical system WL (WL3) according to the third example includes a first lens group G1 having a positive refractive power and a second lens having a positive refractive power, which are arranged in order from the object side. And a group G2. The second lens group G2 includes a front group G2a having a positive refractive power, an aperture stop S, and a rear group G2b having a positive refractive power, which are arranged in order from the object side.

  The first lens group G1 includes a negative meniscus lens L11 having a convex surface directed toward the object side, a positive meniscus lens L12 having a concave surface directed toward the object side, and a biconcave negative lens L13 arranged in order from the object side. The lens includes a biconvex positive lens L14.

  The front group G2a of the second lens group G2 is composed of a biconvex positive lens L21 and a cemented negative lens of a biconvex positive lens L22 and a biconcave negative lens L23 arranged in order from the object side. .

  The rear group G2b of the second lens group G2 includes, in order from the object side, a cemented negative lens of a biconcave negative lens L24 and a biconvex positive lens L25, a biconvex positive lens L26, And a positive meniscus lens L27 having a concave surface on the side. The positive meniscus lens L27 includes an aspheric thin plastic resin layer on the object side lens surface.

  In the optical system WL3 according to the present embodiment, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I during the focusing from the long distance object to the short distance object, and the second lens group G2 Are integrally moved to the object side.

  Table 3 below shows values of various specifications in the third example. Surface numbers 1 to 21 in Table 3 correspond to the optical surfaces m1 to m21 shown in FIG.

(Table 3)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 120.2513 1.500 1.48749 70.41
2 25.3354 15.355
3 -266.4456 3.494 1.83481 42.72
4 -75.2895 1.500 1.49782 82.52
5 38.7750 0.366
6 31.0307 11.000 1.61800 63.37
7 -135.6014 D7 (variable)
8 35.4304 4.295 1.80400 46.57
9 -217.5622 0.389
10 1951.2792 3.406 1.56384 60.67
11 -32.8327 2.055 1.64769 33.80
12 29.3343 3.436
13 ∞ 7.138 (Aperture S)
14 -15.4940 1.150 1.63980 34.56
15 126.4878 3.404 1.72916 54.66
16 -52.2120 0.200
17 507.6958 5.503 1.75500 52.31
18 -26.6794 0.152
* 19 -78.3607 0.150 1.53610 41.21
20 -60.3886 2.803 1.69680 55.52
21 -35.6430 Bf
Image plane ∞

[Aspherical data]
19th surface κ = 1.0000
A4 = -1.37740E-05
A6 = -4.32020E-09
A8 = -1.91520E-11
A10 = 0.00000E + 00

[Overall specifications]
f 35.2
FNo 1.86
ω 32.21
Ymax 21.6
Bf 38.82
TL 116.21

[Variable interval data]
Variable interval infinity short distance D0 ∞ 1044.707
D7 10.100 8.985

[Lens group data]
Group number Group first surface Group focal length G1 1 511.794
G2 8 46.875

[Conditional expression]
Conditional expression (1) νn / νp = 1.302
Conditional expression (2) | f1 | /f=14.547
Conditional expression (3) f2 / f = 1.332
Conditional expression (4) n21 / n22 = 0.949
Conditional expression (5) ν21 / ν22 = 1.822
Conditional expression (6) ν11 / ν12 = 0.518

  From Table 3, it can be seen that the optical system WL3 according to the present example satisfies the conditional expressions (1) to (6).

  FIG. 6 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma diagram, and chromatic aberration diagram of magnification) of the optical system WL3 according to the third example, and (a) is infinite focus. The state (photographing magnification β = 0.00) and (b) show the close-in-focus state (photographing magnification β = −1 / 30).

  From the respective aberration diagrams shown in FIG. 6, it can be seen that the optical system WL3 according to the third example has good optical performance with various aberrations corrected well.

(Fourth embodiment)
A fourth embodiment will be described with reference to FIGS. 7 and 8 and Table 4. FIG. As shown in FIG. 7, the optical system WL (WL4) according to the fourth example includes a first lens group G1 having a positive refractive power and a second lens having a positive refractive power, which are arranged in order from the object side. And a group G2. The second lens group G2 includes a front group G2a having a positive refractive power, an aperture stop S, and a rear group G2b having a positive refractive power, which are arranged in order from the object side.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a cemented negative lens of a biconvex positive lens L12 and a biconcave negative lens L13, It consists of a convex positive lens L14.

  The front lens group G2a of the second lens group G2 is a negative junction of a positive meniscus lens L21 having a convex surface facing the object side, a biconvex positive lens L22, and a biconcave negative lens L23 arranged in order from the object side. It consists of a lens.

  The rear group G2b of the second lens group G2 includes, in order from the object side, a cemented negative lens of a biconcave negative lens L24 and a biconvex positive lens L25, a biconvex positive lens L26, And a positive meniscus lens L27 having a concave surface on the side. The positive meniscus lens L27 includes an aspheric thin plastic resin layer on the object side lens surface.

  In the optical system WL4 according to the present embodiment, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I during the focusing from the long distance object to the short distance object, and the second lens group G2 Are integrally moved to the object side.

  Table 4 below shows values of various specifications in the fourth embodiment. Surface numbers 1 to 21 in Table 4 correspond to the optical surfaces m1 to m21 shown in FIG.

(Table 4)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 155.9697 1.900 1.60311 60.67
2 27.8262 17.205
3 12700.7620 3.520 1.85026 32.35
4 -104.0274 1.500 1.51680 64.10
5 42.1967 0.100
6 31.0797 11.000 1.60311 60.67
7 -100.3267 D7 (variable)
8 32.8683 4.271 1.80400 46.57
9 18768.8410 0.495
10 241.0389 3.162 1.59319 67.90
11 -46.2065 2.694 1.64769 33.80
12 26.7169 3.688
13 ∞ 7.444 (Aperture S)
14 -15.4908 1.100 1.67270 32.11
15 202.7084 2.956 1.69680 55.52
16 -54.3471 0.200
17 381.9504 5.731 1.77250 49.61
18 -25.6649 0.152
* 19 -76.0842 0.150 1.53610 41.21
20 -57.7574 2.708 1.71300 53.88
21 -35.6974 Bf
Image plane ∞

[Aspherical data]
19th surface κ = 1.0000
A4 = -1.42290E-05
A6 = -6.39300E-09
A8 = -2.35130E-11
A10 = 0.00000E + 00

[Overall specifications]
f 35.0
FNo 1.86
ω 32.32
Ymax 21.6
Bf 38.88
TL 117.82

[Variable interval data]
Variable interval infinity short distance D0 ∞ 1029.983
D7 8.965 7.789

[Lens group data]
Group number Group first surface Group focal length G1 1 322.733
G2 8 49.738

[Conditional expression]
Conditional expression (1) νn / νp = 1.000
Conditional expression (2) | f1 | /f=9.221
Conditional expression (3) f2 / f = 1.421
Conditional expression (4) n21 / n22 = 0.967
Conditional expression (5) ν21 / ν22 = 2.009
Conditional expression (6) ν11 / ν12 = 0.505

  From Table 4, it can be seen that the optical system WL4 according to the present example satisfies the conditional expressions (1) to (6).

  FIG. 8 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, coma aberration diagram, and chromatic aberration diagram of magnification) of the optical system WL4 according to the fourth example, and (a) is infinite focus. The state (photographing magnification β = 0.00) and (b) show the close-in-focus state (photographing magnification β = −1 / 30).

  From the respective aberration diagrams shown in FIG. 8, it can be seen that the optical system WL4 according to the fourth example has good optical performance with various aberrations corrected well.

(5th Example)
The fifth embodiment will be described with reference to FIGS. 9 and 10 and Table 5. FIG. As shown in FIG. 9, the optical system WL (WL5) according to the fifth example includes a first lens group G1 having a positive refractive power and a second lens having a positive refractive power, which are arranged in order from the object side. And a group G2. The second lens group G2 includes a front group G2a having a positive refractive power, an aperture stop S, and a rear group G2b having a positive refractive power, which are arranged in order from the object side.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a cemented negative lens of a biconvex positive lens L12 and a biconcave negative lens L13, It consists of a convex positive lens L14.

  The front group G2a of the second lens group G2 is composed of a biconvex positive lens L21 and a cemented negative lens of a biconvex positive lens L22 and a biconcave negative lens L23 arranged in order from the object side. .

  The rear group G2b of the second lens group G2 includes, in order from the object side, a cemented negative lens of a biconcave negative lens L24 and a biconvex positive lens L25, a biconvex positive lens L26, And a positive meniscus lens L27 having a concave surface on the side. The positive meniscus lens L27 includes an aspheric thin plastic resin layer on the object side lens surface.

  In the optical system WL5 according to the present embodiment, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I during the focusing from the long distance object to the short distance object, and the second lens group G2 Are integrally moved to the object side.

  Table 5 below shows values of various specifications in the fifth example. Surface numbers 1 to 21 in Table 5 correspond to the optical surfaces m1 to m21 shown in FIG.

(Table 5)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 262.9687 1.900 1.60311 60.69
2 26.8316 8.607
3 1403.9715 2.641 1.75520 27.57
4 -125.6341 1.500 1.58913 61.22
5 52.0347 5.000
6 39.3275 12.000 1.62299 58.12
7 -76.8163 D7 (variable)
8 33.3127 5.471 1.80400 46.60
9 -324.9547 0.477
10 1244.5691 3.378 1.59319 67.90
11 -38.1119 1.100 1.67270 32.18
12 32.3016 4.496
13 ∞ 8.201 (Aperture S)
14 -17.1903 1.100 1.64769 33.72
15 149.6985 2.433 1.69680 55.52
16 -132.9675 0.150
17 202.1298 6.225 1.77250 49.62
18 -26.2794 0.215
* 19 -172.5191 0.150 1.53610 41.21
20 -97.3007 2.607 1.77250 49.62
21 -49.3164 Bf
Image plane ∞

[Aspherical data]
19th surface κ = 1.0000
A4 = -1.31741E-05
A6 = -5.37825E-09
A8 = -2.84732E-11
A10 = 0.00000E + 00

[Overall specifications]
f 34.4
FNo 1.86
ω 32.75
Ymax 21.6
Bf 38.44
TL 115.92

[Variable interval data]
Variable interval infinity short distance D0 ∞ 1017.084
D7 9.830 8.680

[Lens group data]
Group number Group first surface Group focal length G1 1 541.524
G2 8 50.657

[Conditional expression]
Conditional expression (1) νn / νp = 1.053
Conditional expression (2) | f1 | /f=15.725
Conditional expression (3) f2 / f = 1.471
Conditional expression (4) n21 / n22 = 0.952
Conditional expression (5) ν21 / ν22 = 2.110
Conditional expression (6) ν11 / ν12 = 0.419

  From Table 5, it can be seen that the optical system WL5 according to the present example satisfies the conditional expressions (1) to (6).

  FIG. 10 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma diagram, and lateral chromatic aberration diagram) of the optical system WL5 according to Example 5, and (a) is infinite focus. The state (photographing magnification β = 0.00) and (b) show the close-in-focus state (photographing magnification β = −1 / 30).

  From the respective aberration diagrams shown in FIG. 10, it can be seen that the optical system WL5 according to the fifth example has favorable optical performance with various aberrations corrected well.

(Sixth embodiment)
A sixth embodiment will be described with reference to FIGS. 11 and 12 and Table 6. FIG. As shown in FIG. 11, the optical system WL (WL6) according to the sixth example includes a first lens group G1 having a positive refractive power and a second lens having a positive refractive power, which are arranged in order from the object side. And a group G2. The second lens group G2 includes a front group G2a having a positive refractive power, an aperture stop S, and a rear group G2b having a positive refractive power, which are arranged in order from the object side.

  The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a biconcave shape, and a positive meniscus lens L13 having a convex surface facing the object side. The lens includes a positive lens L14 having a biconvex shape and a cemented positive lens of a negative meniscus lens L15 having a concave surface facing the object side.

  The front lens group G2a of the second lens group G2 is a negative junction of a positive meniscus lens L21 having a convex surface facing the object side, a biconvex positive lens L22, and a biconcave negative lens L23 arranged in order from the object side. It consists of a lens.

  The rear group G2b of the second lens group G2 includes, in order from the object side, a cemented negative lens of a biconcave negative lens L24 and a biconvex positive lens L25, a biconvex positive lens L26, And a positive meniscus lens L27 having a concave surface on the side. The positive meniscus lens L27 includes an aspheric thin plastic resin layer on the object side lens surface.

  In the optical system WL6 according to the present embodiment, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I during the focusing from the long distance object to the short distance object, and the second lens group G2 Are integrally moved to the object side.

  Table 6 below shows values of various specifications in the sixth example. Surface numbers 1 to 22 in Table 6 correspond to the optical surfaces m1 to m22 shown in FIG.

(Table 6)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 161.0107 1.400 1.58913 61.22
2 24.2058 9.782
3 -204.8402 1.400 1.58913 61.22
4 51.7585 1.841 1.75520 27.57
5 55.4234 3.966
6 42.1254 11.413 1.74397 44.85
7 -31.7310 1.400 1.74118 28.17
8 -71.8021 D8 (variable)
9 28.9208 4.796 1.74777 36.94
10 301.5981 0.824
11 148.4800 3.106 1.58913 61.22
12 -100.4800 1.500 1.68893 31.16
13 30.2892 3.772
14 ∞ 7.408 (Aperture S)
15 -18.1540 1.500 1.75520 27.58
16 103.1328 3.426 1.74397 44.85
17 -56.7564 0.150
18 204.2182 5.591 1.74397 44.85
19 -28.1452 0.220
* 20 -146.3219 0.150 1.55389 38.23
21 -76.9188 2.555 1.60311 60.69
22 -47.6199 Bf
Image plane ∞

[Aspherical data]
20th surface κ = 1.0000
A4 = -1.39076E-05
A6 = -2.19882E-09
A8 = -3.54595E-11
A10 = 0.00000E + 00

[Overall specifications]
f 34.3
FNo 1.85
ω 32.77
Ymax 21.6
Bf 38.55
TL 114.35

[Variable interval data]
Variable interval infinity short distance D0 ∞ 1014.207
D8 9.600 8.449

[Lens group data]
Group number Group first surface Group focal length G1 1 348.769
G2 9 52.265

[Conditional expression]
Conditional expression (1) νn / νp = 1.365
Conditional expression (2) | f1 | /f=10.165
Conditional expression (3) f2 / f = 1.523
Conditional expression (4) n21 / n22 = 0.941
Conditional expression (5) ν21 / ν22 = 1.965
Conditional expression (6) ν11 / ν12 = 0.450

  From Table 6, it can be seen that the optical system WL6 according to the present example satisfies the conditional expressions (1) to (6).

  FIG. 12 is a diagram illustrating various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma diagram, and chromatic aberration diagram of magnification) of the optical system WL6 according to the sixth example, and (a) is infinite focus. The state (photographing magnification β = 0.00) and (b) show the close-in-focus state (photographing magnification β = −1 / 30).

  From the aberration diagrams shown in FIG. 12, it can be seen that the optical system WL6 according to the sixth example has various optical aberrations corrected and has good optical performance.

(Seventh embodiment)
A seventh embodiment will be described with reference to FIGS. 13 and 14 and Table 7. FIG. As shown in FIG. 13, the optical system WL (WL7) according to the seventh example includes a first lens group G1 having a positive refractive power and a second lens having a positive refractive power, which are arranged in order from the object side. And a group G2. The second lens group G2 includes a front group G2a having a positive refractive power, an aperture stop S, and a rear group G2b having a positive refractive power, which are arranged in order from the object side.

  The first lens group G1 includes a negative meniscus lens L11 having a convex surface directed toward the object side, a positive meniscus lens L12 having a concave surface directed toward the object side, and a biconcave negative lens L13 arranged in order from the object side. The lens includes a positive lens L14 having a biconvex shape and a cemented positive lens of a negative meniscus lens L15 having a concave surface facing the object side.

  The front lens group G2a of the second lens group G2 is a negative junction of a positive meniscus lens L21 having a convex surface facing the object side, a biconvex positive lens L22, and a biconcave negative lens L23 arranged in order from the object side. It consists of a lens.

  The rear lens group G2b of the second lens group G2 includes a cemented negative lens composed of a negative meniscus lens L24 having a concave surface facing the object side and a positive meniscus lens L25 having a concave surface facing the object side. A positive lens L26 having a shape and a positive meniscus lens L27 having a concave surface facing the object side. The positive meniscus lens L27 includes an aspheric thin plastic resin layer on the object side lens surface.

  In the optical system WL7 according to the present embodiment, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I during focusing from a long distance object to a short distance object, and the second lens group G2 Are integrally moved to the object side.

  Table 7 below shows values of each item in the seventh example. Surface numbers 1 to 22 in Table 7 correspond to the optical surfaces m1 to m22 shown in FIG.

(Table 7)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 153.5749 1.400 1.58913 61.22
2 25.4245 10.376
3 -138.8912 3.062 1.75520 27.57
4 -62.7707 1.000 1.51680 63.88
5 45.7911 1.965
6 37.7423 11.178 1.74400 44.80
7 -37.0168 1.400 1.75520 27.57
8 -84.1449 D8 (variable)
9 30.1541 4.744 1.77250 49.62
10 485.2701 0.660
11 242.4579 2.766 1.58913 61.22
12 -115.8962 1.500 1.68893 31.16
13 28.8001 3.800
14 ∞ 8.084 (Aperture S)
15 -16.8048 1.500 1.75520 27.57
16 -460.7409 3.561 1.74400 44.80
17 -36.5823 0.150
18 284.5507 5.925 1.74400 44.80
19 -29.1162 0.220
* 20 -90.8346 0.150 1.55389 38.23
21 -59.2411 2.760 1.60311 60.69
22 -40.0106 Bf
Image plane ∞

[Aspherical data]
20th surface κ = 1.0000
A4 = -1.20837E-05
A6 = -1.37637E-09
A8 = -2.30450E-11
A10 = 0.00000E + 00

[Overall specifications]
f 34.5
FNo 1.86
ω 32.59
Ymax 21.6
Bf 38.55
TL 114.35

[Variable interval data]
Variable interval infinity short distance D0 ∞ 1018.989
D8 9.600 8.440

[Lens group data]
Group number Group first surface Group focal length G1 1 338.536
G2 9 48.973

[Conditional expression]
Conditional expression (1) νn / νp = 1.426
Conditional expression (2) | f1 | /f=9.800
Conditional expression (3) f2 / f = 1.418
Conditional expression (4) n21 / n22 = 0.941
Conditional expression (5) ν21 / ν22 = 1.965
Conditional expression (6) ν11 / ν12 = 0.432

  From Table 7, it can be seen that the optical system WL7 according to the present example satisfies the conditional expressions (1) to (6).

  FIG. 14 is a diagram illustrating various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma diagram, and chromatic aberration diagram of magnification) of the optical system WL7 according to the seventh example, and (a) is focused at infinity. The state (photographing magnification β = 0.00) and (b) show the close-in-focus state (photographing magnification β = −1 / 30).

  From the aberration diagrams shown in FIG. 14, it can be seen that the optical system WL7 according to the seventh example has various optical aberrations corrected and has good optical performance.

(Eighth embodiment)
The eighth embodiment will be described with reference to FIGS. 15 and 16 and Table 8. FIG. As shown in FIG. 15, the optical system WL (WL8) according to the eighth example includes a first lens group G1 having negative refractive power and a second lens having positive refractive power, which are arranged in order from the object side. And a group G2. The second lens group G2 includes a front group G2a having a positive refractive power, an aperture stop S, and a rear group G2b having a positive refractive power, which are arranged in order from the object side.

  The first lens group G1 includes a negative meniscus lens L11 having a convex surface directed toward the object side, a positive meniscus lens L12 having a concave surface directed toward the object side, and a biconcave negative lens L13 arranged in order from the object side. The lens includes a biconvex positive lens L14.

  The front lens group G2a of the second lens group G2 is a negative junction of a biconvex positive lens L21 arranged in order from the object side, a positive meniscus lens L22 having a concave surface facing the object side, and a biconcave negative lens L23. It consists of a lens.

  The rear lens group G2b of the second lens group G2 includes a cemented negative lens composed of a negative meniscus lens L24 having a concave surface facing the object side and a positive meniscus lens L25 having a concave surface facing the object side. A positive lens L26 having a shape and a positive meniscus lens L27 having a concave surface facing the object side. The positive meniscus lens L27 includes an aspheric thin plastic resin layer on the object side lens surface.

  In the optical system WL8 according to the present embodiment, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I during the focusing from the long distance object to the short distance object, and the second lens group G2 Are integrally moved to the object side.

  Table 8 below shows values of various specifications in the eighth embodiment. Surface numbers 1 to 21 in Table 8 correspond to the optical surfaces m1 to m21 shown in FIG.

(Table 8)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 110.5805 1.400 1.69680 55.52
2 27.8981 9.431
3 -131.5963 3.958 1.82971 39.47
4 -50.4495 1.000 1.55247 58.39
5 42.6428 1.665
6 38.8658 7.313 1.81468 46.65
7 -178.6735 D7 (variable)
8 38.6831 5.261 1.81600 46.59
9 -152.3909 0.200
10 -435.2892 3.444 1.59319 67.90
11 -42.7218 1.500 1.67270 32.18
12 41.9571 7.054
13 ∞ 8.190 (Aperture S)
14 -17.0130 1.500 1.75520 27.57
15 -349.4823 2.357 1.77250 49.62
16 -71.5078 0.200
17 445.8012 5.272 1.80400 46.60
18 -27.2875 0.200
* 19 -148.5412 0.200 1.55389 38.23
20 -86.8201 3.388 1.77250 49.62
21 -37.5228 Bf
Image plane ∞

[Aspherical data]
19th surface κ = 1.0000
A4 = -1.35804E-05
A6 = 2.35944E-10
A8 = -2.81459E-11
A10 = 0.00000E + 00

[Overall specifications]
f 34.0
FNo 1.86
ω 33.01
Ymax 21.6
Bf 38.55
TL 111.69

[Variable interval data]
Variable interval infinity short distance D0 ∞ 1004.995
D8 9.600 8.460

[Lens group data]
Group number Group first surface Group focal length G1 1 -504.559
G2 8 45.000

[Conditional expression]
Conditional expression (1) νn / νp = 1.252
Conditional expression (2) | f1 | /f=14.840
Conditional expression (3) f2 / f = 1.324
Conditional expression (4) n21 / n22 = 0.952
Conditional expression (5) ν21 / ν22 = 2.110
Conditional expression (6) ν11 / ν12 = 0.676

  From Table 8, it can be seen that the optical system WL8 according to the present example satisfies the conditional expressions (1) to (6).

  FIG. 16 is a diagram illustrating various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma diagram, and chromatic aberration diagram of magnification) of the optical system WL8 according to Example 8, and (a) is infinite focus. The state (photographing magnification β = 0.00) and (b) show the close-in-focus state (photographing magnification β = −1 / 30).

  From the respective aberration diagrams shown in FIG. 16, it can be seen that the optical system WL8 according to the eighth example has favorable optical performance with various aberrations corrected well.

(Ninth embodiment)
A ninth embodiment will be described with reference to FIGS. 17 and 18 and Table 9. FIG. As shown in FIG. 17, the optical system WL (WL9) according to the ninth example includes a first lens group G1 having negative refractive power and a second lens having positive refractive power, which are arranged in order from the object side. And a group G2. The second lens group G2 includes a front group G2a having a positive refractive power, an aperture stop S, and a rear group G2b having a positive refractive power, which are arranged in order from the object side.

  The first lens group G1 includes a negative meniscus lens L11 having a convex surface directed toward the object side, a positive meniscus lens L12 having a concave surface directed toward the object side, and a biconcave negative lens L13 arranged in order from the object side. The lens includes a biconvex positive lens L14.

  The front group G2a of the second lens group G2 is composed of a biconvex positive lens L21 and a cemented negative lens of a biconvex positive lens L22 and a biconcave negative lens L23 arranged in order from the object side. .

  The rear lens group G2b of the second lens group G2 includes a cemented negative lens composed of a negative meniscus lens L24 having a concave surface facing the object side and a positive meniscus lens L25 having a concave surface facing the object side. A positive lens L26 having a shape and a positive meniscus lens L27 having a concave surface facing the object side. The positive meniscus lens L27 includes an aspheric thin plastic resin layer on the object side lens surface.

  In the optical system WL9 according to the present embodiment, the first lens group G1 is fixed in the optical axis direction with respect to the image plane I during the focusing from the long distance object to the short distance object, and the second lens group G2 Moves to the object side. At this time, in the second lens group G2, the front group G2a and the aperture stop S move integrally so that the distance between the front group G2a and the rear group G2b is reduced, and the front group G2a and the aperture stop S are also moved. The rear group G2b moves with a different movement amount.

  Table 9 below shows values of various specifications in the ninth embodiment. Surface numbers 1 to 21 in Table 9 correspond to the optical surfaces m1 to m21 shown in FIG.

(Table 9)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 350.0000 1.400 1.69680 55.52
2 30.6460 9.670
3 -172.9804 4.014 1.81600 46.59
4 -53.7236 1.000 1.51680 63.88
5 48.8553 0.200
6 38.5318 7.582 1.73681 51.06
7 -137.0708 D7 (variable)
8 33.5680 5.506 1.81600 46.59
9 -441.5664 0.850
10 452.4992 3.472 1.59319 67.90
11 -51.2236 1.500 1.67270 32.18
12 34.4298 3.501
13 ∞ D13 (variable) (Aperture S)
14 -17.1577 1.500 1.75520 27.57
15 -196.4053 1.938 1.77250 49.62
16 -107.4521 0.200
17 152.6448 6.188 1.80400 46.60
18 -25.7414 0.200
* 19 -147.6868 0.200 1.55389 38.23
20 -76.9492 2.839 1.77250 49.62
21 -43.4978 Bf
Image plane ∞

[Aspherical data]
19th page
κ = 1.0000
A4 = -1.50665E-05
A6 = -5.88959E-09
A8 = -4.03994E-11
A10 = 0.00000E + 00

[Overall specifications]
f 36.0
FNo 1.86
ω 31.47
Ymax 21.6
Bf 38.55
TL 112.35

[Variable interval data]
Variable interval infinity short distance D0 ∞ 1064.367
D7 13.493 12.440
D13 8.547 8.369

[Lens group data]
Group number Group first surface Group focal length G1 1 -750.002
G2 8 47.000

[Conditional expression]
Conditional expression (1) νn / νp = 1.087
Conditional expression (2) | f1 | /f=20.843
Conditional expression (3) f2 / f = 1.306
Conditional expression (4) n21 / n22 = 0.952
Conditional expression (5) ν21 / ν22 = 2.110
Conditional expression (6) ν11 / ν12 = 0.729

  From Table 9, it can be seen that the optical system WL9 according to the present example satisfies the conditional expressions (1) to (6).

  FIG. 18 is a diagram illustrating various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma diagram, and chromatic aberration diagram of magnification) of the optical system WL9 according to Example 9, and (a) is infinite focus. The state (photographing magnification β = 0.00) and (b) show the close-in-focus state (photographing magnification β = −1 / 30).

  From each aberration diagram shown in FIG. 18, it can be seen that the optical system WL9 according to Example 9 has various aberrations corrected well and has good optical performance.

  So far, in order to make the present invention easy to understand, the configuration requirements of the embodiment have been described, but the present invention is not limited to this. The contents described below can be appropriately adopted as long as the optical performance is not impaired.

  In the above embodiment, the two-group configuration is shown, but the present invention can be applied to other group configurations such as the third group, the fourth group, and the like. Specifically, a configuration in which a lens or a lens group is added to the most object side of the optical system WL according to the present embodiment, or a configuration in which a lens or a lens group is added to the most image side may be used. The lens group refers to a portion having at least one lens separated by an air interval that changes during focusing or zooming.

  In the optical system WL according to this embodiment, the lens surface may be formed as a spherical surface or a flat surface, or may be formed as an aspheric surface. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment are facilitated, and optical performance deterioration due to errors in processing and assembly adjustment can be prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is an aspheric surface, the aspheric surface is an aspheric surface by grinding, a glass mold aspheric surface made of glass with an aspheric shape, or a composite aspheric surface made of resin with an aspheric shape on the glass surface. Any aspherical surface may be used. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

  In the optical system WL according to the present embodiment, it is preferable that the aperture stop S is disposed in the second lens group G2, but instead of providing a member as an aperture stop, the role of the lens stop is substituted. Also good.

  An antireflection film having high transmittance in a wide wavelength range may be provided on each surface of the lens constituting the optical system WL according to the present embodiment. With this configuration, it is possible to reduce flare and ghost and achieve high optical performance with high contrast.

WL (WL1 to WL9) Optical system G1 First lens group G2 Second lens group S Aperture stop I Image surface 1 Camera (optical device)

Claims (9)

  1. A first lens group and a second lens group having a positive refractive power, arranged in order from the object side;
    The first lens group includes a negative lens and a positive lens,
    When focusing from an object at infinity to an object at a short distance, the first lens group is fixed in the optical axis direction with respect to the image plane, the second lens group is moved, and the first lens group and the first lens group are moved. The distance between the two lens groups changes,
    An optical system satisfying the following conditional expression:
    0.50 <νn / νp <1.60
    5.00 <| f1 | / f <30.00
    1.15 <f2 / f <1.70
    However,
    ν n: Abbe number based on the d-line of the glass material of the lens having the strongest negative refractive power in the first lens group,
    νp: Abbe number based on the d-line of the glass material of the lens having the strongest positive refractive power in the first lens group,
    f1: the focal length of the first lens group,
    f2: focal length of the second lens group,
    f: The focal length of the entire system in the infinitely focused state.
  2.   The optical system according to claim 1, wherein the first lens group includes a cemented lens.
  3. Among the cemented lenses included in the first lens group, the cemented lens located closest to the object side of the lens having the strongest positive refractive power includes a negative lens and a positive lens.
    The optical system according to claim 2, wherein the following conditional expression is satisfied.
    0.20 <ν11 / ν12 <1.00
    However,
    ν11: Abbe number based on the d-line of the glass material of the positive lens constituting the cemented lens closest to the object side of the lens having the strongest positive refractive power in the first lens group,
    ν12: Abbe number based on the d-line of the glass material of the negative lens constituting the cemented lens closest to the object side of the lens having the strongest positive refractive power in the first lens group.
  4. The second lens group includes an aperture stop, a lens having the strongest negative refractive power in the lens group positioned closer to the object side than the aperture stop, and a positive lens positioned immediately before the object side of the negative lens. And
    The optical system according to claim 1, wherein the following conditional expression is satisfied.
    0.60 <n21 / n22 <1.00
    However,
    n21: The refractive index of the lens material having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop in the second lens group with respect to the d-line of the glass material of the positive lens located immediately before the object side ,
    n22: a refractive index with respect to d-line of the glass material of the lens having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop in the second lens group.
  5. The second lens group includes an aperture stop, a lens having the strongest negative refractive power in the lens group positioned closer to the object side than the aperture stop, and a positive lens positioned immediately before the object side of the negative lens. And
    The optical system according to claim 1, wherein the following conditional expression is satisfied.
    1.40 <ν21 / ν22 <2.80
    However,
    ν 21: Based on the d-line of the glass material of the positive lens located immediately before the object side of the lens unit having the strongest negative refractive power in the lens group located on the object side of the aperture stop in the second lens group Abbe number,
    ν22: Abbe number based on the d-line of the glass material of the lens having the strongest negative refractive power in the lens group located closer to the object side than the aperture stop in the second lens group.
  6.   The second lens group includes an aperture stop, a front group located closer to the object side than the aperture stop, and a rear group located closer to the image side than the aperture stop. Each of the groups is moved while maintaining or changing a distance between the front group and the rear group at the time of focusing. The optical system described in 1.
  7.   The optical system according to claim 1, wherein the second lens group includes at least one aspheric lens.
  8.   An optical apparatus comprising the optical system according to any one of claims 1 to 7.
  9. A method of manufacturing an optical system having a first lens group and a second lens group having a positive refractive power, arranged in order from the object side,
    The first lens group includes a negative lens and a positive lens,
    When focusing from an object at infinity to an object at a short distance, the first lens group is fixed in the optical axis direction with respect to the image plane, the second lens group is moved, and the first lens group and the first lens group are moved. The distance between the two lens groups changes,
    A method of manufacturing an optical system, wherein each lens is arranged in a lens barrel so as to satisfy the following conditional expression:
    0.50 <νn / νp <1.60
    5.00 <| f1 | / f <30.00
    1.15 <f2 / f <1.70
    However,
    ν n: Abbe number based on the d-line of the glass material of the lens having the strongest negative refractive power in the first lens group,
    νp: Abbe number based on the d-line of the glass material of the lens having the strongest positive refractive power in the first lens group,
    f1: the focal length of the first lens group,
    f2: focal length of the second lens group,
    f: The focal length of the entire system in the infinitely focused state.
JP2013260469A 2013-12-17 2013-12-17 Optical system, optical instrument, and method for manufacturing optical system Pending JP2015118186A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2013260469A JP2015118186A (en) 2013-12-17 2013-12-17 Optical system, optical instrument, and method for manufacturing optical system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2013260469A JP2015118186A (en) 2013-12-17 2013-12-17 Optical system, optical instrument, and method for manufacturing optical system

Publications (1)

Publication Number Publication Date
JP2015118186A true JP2015118186A (en) 2015-06-25

Family

ID=53530968

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2013260469A Pending JP2015118186A (en) 2013-12-17 2013-12-17 Optical system, optical instrument, and method for manufacturing optical system

Country Status (1)

Country Link
JP (1) JP2015118186A (en)

Similar Documents

Publication Publication Date Title
JP5115102B2 (en) Lens system and optical device
JP5423190B2 (en) Variable magnification optical system and optical apparatus provided with the variable magnification optical system
JP5380811B2 (en) Wide-angle lens and imaging device
JP4632724B2 (en) Zoom lens
JP5167724B2 (en) Optical system
JP5448028B2 (en) Zoom lens and optical apparatus having the same
JP5263589B2 (en) Zoom lens system, optical apparatus equipped with the zoom lens system, and zooming method using the zoom lens system
JP5407119B2 (en) Variable magnification optical system, optical apparatus, and variable magnification optical system magnification method
JP5288238B2 (en) Magnifying optical system, optical apparatus equipped with the magnifying optical system, and magnifying method of the magnifying optical system
JP5104084B2 (en) Wide-angle lens, optical device, and wide-angle lens focusing method
US7924511B2 (en) Optical system, method for focusing, and imaging apparatus equipped therewith
US7599123B2 (en) Zoom lens system, imaging apparatus and method for varying focal length
JP5253051B2 (en) Zoom lens and imaging apparatus having the same
JP5641680B2 (en) Zoom lens and optical apparatus having the same
JP4946445B2 (en) Wide-angle lens, imaging device, and wide-angle lens focusing method
JP5904273B2 (en) Variable magnification optical system, optical apparatus, and variable magnification optical system manufacturing method
JP5581730B2 (en) Variable magnification optical system, optical device
JP5458477B2 (en) Variable magnification optical system, optical apparatus, and variable magnification optical system magnification method
JP4950608B2 (en) Zoom lens and imaging apparatus having the same
JP4924003B2 (en) Wide-angle lens, imaging device, and wide-angle lens focusing method
JP5402015B2 (en) Rear focus optical system, imaging apparatus, and focusing method of rear focus optical system
JP5510113B2 (en) Photographic lens, optical apparatus equipped with photographic lens, and method of manufacturing photographic lens
US7283311B2 (en) Wide-angle zoom lens system
JP2011186159A (en) Variable power optical system, optical device, and method for manufacturing variable power optical system
JP2008003511A (en) Zoom lens with vibration-proof function, imaging apparatus, vibration preventing method for zoom lens, and power varying method for zoom lens