JP2017223755A - Imaging optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging optical system that is small and has good optical performance, a wide angle of view and a large aperture.SOLUTION: The imaging optical system is composed of, successively from an object side to an image side, a front group GF disposed on an object side of an aperture diaphragm, an aperture diaphragm SS, and a rear group GR disposed on an image side of the aperture diaphragm SS. The front group GF is composed of, successively from the object side, a partial group GFn having a negative refractive power in which a meniscus negative lens is present closest to the object and has a convex surface on the object side, and a partial group GFp having a positive refractive power. The rear group GR is composed of, successively from the object side, a positive lens LR1p having both convex surfaces, a positive lens LR2p, and a negative lens LR3n having both concave surfaces. The optical system satisfies conditional expressions (1) -0.2<fA/fF<0.2 and (2) -0.5<(RR1b+Rr1a)/(RR1b-Rr1a)<0.2, where fA represents the focal distance of the entire optical system, fF represents the focal distance of the front group GF, RR1b represents a radius of curvature on an image side surface of a positive lens LR1p in the rear group GR, and RR1a represents a radius of curvature on an object side surface of a positive lens LR1p in the rear group GR.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging optical system. For example, the present invention relates to an imaging optical system suitable for a digital still camera, a digital video camera, and the like.

  In recent years, in an imaging apparatus such as a digital still camera and a digital video camera using an electronic imaging element, an optical system having a small size and good optical performance has been demanded. In addition, in an optical system used for a surveillance camera or the like, an optical system having a wide angle of view and a large aperture is required in order to expand an imaging area in one shot.

  2. Description of the Related Art Conventionally, as an in-vehicle surveillance camera optical system, a small optical system having a wide angle of view of about 90 degrees and an aperture ratio of about 2.0 has been known (Patent Document). 1).

JP 2009-75141 A

  In the optical system disclosed in Patent Document 1, correction of spherical aberration tends to be insufficient, and it has been difficult to realize a larger aperture while maintaining optical performance.

  In particular, in an optical system used for monitoring or the like, it is required to ensure a wider angle of view on the image sensor surface. That is, if the imaging optical system is configured to have an optical performance that can withstand electronic correction processing (stretching operation), it is preferable that a certain amount of negative distortion is left from the viewpoint of miniaturization of the optical system.

  Here, the optical system disclosed in Patent Document 1 optically corrects negative distortion aberration in order to ensure image quality in the peripheral portion. For this reason, the angle of view that actually forms an image on the image sensor surface is narrower than when negative distortion remains, and an attempt to achieve a wider angle of view results in a larger optical system. End up.

  An object of the present invention is to provide a small imaging optical system having good optical performance, a wide angle of view, a large aperture, and a small size.

In order to achieve the above object, an imaging optical system according to the present invention includes:
A front group aperture stop that is arranged on the object side from the aperture stop in order from the object side to the image side is configured by a rear group that is arranged on the image side from the aperture stop. A negative lens having a meniscus shape with a convex surface facing, a sub-group having a negative refractive power and a positive refractive power sub-group, the rear group being a biconvex positive lens in order from the object side. The focal length of the entire optical system consisting of lenses is fA
The focal length of the front group is fF
The radius of curvature on the image side surface of the biconvex positive lens disposed on the most object side in the rear group is defined as RR1b.
The radius of curvature of the object side surface of the biconvex positive lens disposed closest to the object side in the rear group is defined as RR1a.
The following conditional expression is satisfied.
-0.2 <fA / fF <0.2 (1)
−0.5 <(RR1b + RR1a) / (RR1b−RR1a) <0.2
... (2)

  According to the present invention, it is possible to provide a small imaging optical system having good optical performance, a wide angle of view, a large aperture, and a small size.

Lens sectional view of Example 1 Longitudinal aberration diagram of Example 1 when focusing on infinity Lens sectional view of Example 2 Longitudinal aberration diagram of Example 2 during focusing on infinity Lens sectional view of Example 3 Longitudinal aberration diagram of Example 3 during focusing on infinity Lens sectional view of Example 4 Longitudinal aberration diagram of Example 4 during focusing on infinity Lens sectional view of Example 5 Longitudinal aberration diagram of Example 5 during focusing on infinity

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  The optical system according to the present invention includes, in order from the object side to the image side, a front group disposed on the object side from the aperture stop, an aperture stop, and a rear group disposed on the image side from the aperture stop. In addition, the front group includes, in order from the object side, a negative refractive power subgroup having a meniscus negative lens with a convex surface facing the object side closest to the object side, and a positive refractive power subgroup. . The rear group includes, in order from the object side, a biconvex positive lens, a positive lens, and a biconcave negative lens.

  1, FIG. 3, FIG. 5, FIG. 7, and FIG. 9 are lens cross-sectional views when focusing on an object at infinity according to first to fifth embodiments of the present invention. 2, FIG. 4, FIG. 6, FIG. 8, and FIG. 10 are longitudinal aberration diagrams at the time of focusing on an object at infinity according to Examples 1 to 5 of the present invention.

  The optical system of each embodiment is a photographic lens system used in the imaging apparatus. In the lens cross-sectional view, the left side is the subject side (object side) and the right side is the image side (rear).

  In the lens cross-sectional view, LF is a front group having an effect equivalent to a wide converter. LR is a rear group of positive refractive power (optical power = reciprocal of focal length). SS is an aperture stop. GFn is a negative refractive power subgroup arranged in the front group GF. GFp is a positive refractive power subgroup arranged in the front group GF. LR1p is a biconvex positive lens disposed on the most object side in the rear group GR. LR2p is a positive lens arranged on the image side of LR1p in the rear group GR. LR3n is a biconcave negative lens disposed on the most image side in the rear group GR. G is a glass block corresponding to a cover glass of the solid-state image sensor or various optical filters. IP is an image plane corresponding to an image pickup surface of a solid-state image pickup device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor.

  In the longitudinal aberration diagrams, d-line and g-line are d-line and g-line, respectively, and ΔM and ΔS are a meridional image plane and a sagittal image plane. Lateral chromatic aberration is represented by the g-line. ω is a shooting half angle of view (degrees) corresponding to the ideal image height, and Fno is an F number.

In each embodiment, the focal length of the entire optical system is fA. Further, the focal length of the front group GF arranged on the object side with respect to the aperture stop SS is defined as fF. In addition, the curvature radius of the object side surface of the positive lens LR1p disposed on the most object side of the rear group GR disposed on the image side of the stop SS is RR1a, and the curvature radius of the image side surface is RR1b. Here, when the positive lens LR1p is an aspherical lens, the curvature radius is a paraxial curvature radius.
At this time,
-0.2 <fA / fF <0.2 (1)
−0.5 <(RR1b + Rr1a) / (RR1b−Rr1a) <0.2
... (2)
The following conditional expression is satisfied.

  In the present invention, it is important to satisfy the conditional expressions (1) and (2) at the same time in order to achieve both a large aperture, high performance, and downsizing of the wide-angle optical system.

  Conditional expression (1) is a conditional expression that defines the ratio of the focal length of the front group GF arranged on the object side of the stop and the focal length of the entire optical system. When the conditional expression (1) is satisfied, the front group has a substantially afocal configuration, and the role of the wide converter is arranged for the rear group GR.

  Conditional expression (2) is a conditional expression that defines the lens shape of the positive lens LR1p arranged closest to the object side in the rear group GR. By satisfying conditional expression (1), spherical aberration generated in the positive lens LR1p is corrected well.

  Here, it is important to clarify the division of roles of the front group GF and the rear group GR in order to achieve both a reduction in size and high performance of the entire optical system and an increase in diameter. In other words, by taking a refractive power arrangement that satisfies the conditional expression (1), the front group GF can serve as a wide converter for capturing a wide angle of view, and the rear group GR can serve as a master lens having a converging function. Here, by taking the configuration satisfying the conditional expression (2) for the rear group GR, it is possible to satisfactorily correct the spherical aberration generated in the rear group GR that is a master lens within the group.

  If the refractive power of the front group GF is too strong beyond the range of the conditional expression (1), various aberrations remaining in the front group, particularly spherical aberration, are shared and corrected by the rear group GR, and the entire optical system It is difficult to achieve both the miniaturization and high performance.

  When the upper limit of conditional expression (2) is exceeded, the curvature of the object side surface of the positive lens LR1p becomes too loose, and the refractive action on this surface becomes too small. When the lower limit of conditional expression (2) is exceeded, the curvature of the object side surface of the positive lens LR1p becomes too tight, and the refracting action on this surface becomes too large. In either case, since the spherical aberration generated in the positive lens LR1p is largely undercorrected, spherical aberration remains in the rear group GR, making it difficult to increase the diameter of the entire optical system.

  As a result, each embodiment realizes a small imaging optical system having good optical performance, a wide angle of view, a large aperture, and a small diameter.

  In each embodiment, the numerical ranges of conditional expressions (1) and (2) are preferably set as follows.

−0.15 <fA / fF <0.1 (1a)
−0.45 <(RR1b + Rr1a) / (Rr1b−RR1a) <0.1
... (2a)
In each embodiment, more preferably, the numerical ranges of the conditional expressions (1a) and (2a) are set as follows.

−0.1 <fA / fF <0.05 (1b)
−0.4 <(RR1b + RR1a) / (RR1b−R1a) <0.05
... (2b)
In the optical system of the present invention, it is more preferable to satisfy one or more of the following conditional expressions.

  Let fR1p be the focal length of the biconvex positive lens LR1p disposed on the most object side in the rear group GR. In the rear group GR, the combined focal length of the positive lens LR2p and the biconcave negative lens LR3n arranged on the image side from fR1p is defined as fR23. Further, the radius of curvature of the image side surface of the biconcave negative lens LR3n arranged on the most image side of the rear group GR is RR3b, and the radius of curvature of the object side surface is RR3a. Here, when the negative lens LR3n is an aspheric lens, the radius of curvature is a paraxial radius of curvature. Further, the focal length of the negative refractive power subgroup GFn disposed in the front group GF is fFn, and the focal length of the positive refractive power subgroup GFp is fFp. The Abbe number of the optical material of the positive lens LR1p is νdR1p. The Abbe number of the optical material of the negative lens LR3n is νdR3n.

  At this time, it is preferable to satisfy one or more of the following conditions.

-1.0 <fR1p / fR23 <0.0 (3)
−0.7 <(RR3b + RR3a) / (RR3b−RR3a) <0.9
(4)
−0.8 <fFn / fFp <−0.3 (5)
50.0 <νdR1p <100.0 (6)
10.0 <νdR3n <25.0 (7)
Next, the technical meaning of each conditional expression will be described.

  Conditional expression (3) is a conditional expression that defines the refractive power arrangement within the rear group GR arranged on the image side from the aperture stop. As described above, since the rear group GR in the present invention is a master lens group having a converging function, it is important to sufficiently correct each aberration within the group. By making the refractive power arrangement satisfying the conditional expression (3), spherical aberration and chromatic aberration are favorably corrected particularly in the rear group GR group.

  When the lower limit of conditional expression (3) is exceeded, the focal length of the positive lens LR1p becomes too long, and the positive refractive power becomes too weak in the entire rear group GR, which makes it difficult to widen the angle of view in the entire optical system. Become. On the other hand, if the upper limit is exceeded, the focal length of the composite lens LR23 of the positive lenses LR2p and LR2n becomes positive. At this time, it is difficult to correct the spherical aberration and chromatic aberration remaining in the positive lens LR1p within the rear group GR group.

  Conditional expression (4) is a conditional expression that defines the lens shape of the negative lens LR3n disposed on the most image side in the rear group GR. By satisfying conditional expression (4), the spherical aberration remaining in the positive lens LR1p is satisfactorily corrected, and negative distortion is controlled as the entire optical system.

  When the lower limit of conditional expression (4) is exceeded, the curvature of the object side surface of the negative lens LR3n becomes too loose. At this time, high-order spherical aberration generated in the positive lens LR1p is insufficiently corrected, and it becomes difficult to increase the diameter of the optical system. On the other hand, if the upper limit is exceeded, the curvature of the image side surface of the negative lens LR3n becomes too loose. At this time, the negative distortion aberration is insufficiently corrected in the entire optical system. In other words, the residual amount of negative distortion becomes too large, and image quality deterioration becomes large when electronic correction processing (stretching operation) is taken into consideration, so that it is difficult to improve image quality.

  In the optical system of the present invention, the rear group GR has a telephoto configuration in which a biconvex positive lens LR1p, a positive lens LR2p, and a biconcave negative lens LR3n are arranged in order from the object side. Is placed on the object side to reduce the size of the master optical system. Further, by using the positive lens LR2p and the negative lens LR3n as a cemented lens, the decentering sensitivity of the surface is reduced and the lens barrel configuration is simplified.

  Conditional expression (5) is a conditional expression that defines the in-group configuration of the front group GF disposed on the object side from the aperture stop. As described above, the front group GF in the present invention constitutes a substantially afocal system that satisfies the conditional expression (1), and has the role of a wide converter for capturing a wide angle of view. Here, if the front group GF constitutes an afocal optical system, the conditional expression (5) defines the afocal magnification.

  If the lower limit of conditional expression (5) is exceeded, the afocal magnification of the front group GF will be too close to the same magnification. At this time, in order to widen the angle of view of the entire optical system, the refractive power of the rear group GR, which is the master group, will be strengthened. It becomes difficult. On the other hand, if the upper limit is exceeded, the afocal magnification of the front group GF will increase too much. At this time, the focal length of the positive refractive power subgroup GFp constituting the front group GF becomes too long, and when the afocal system is formed, the front group GF becomes large and it is difficult to downsize the entire optical system.

  Conditional expression (6) is a conditional expression that defines the Abbe number of the optical material of the biconvex positive lens LR1p arranged closest to the object side in the rear group GR. The positive lens LR1p shares the main refractive power in the rear group GR, and suppresses the occurrence of chromatic aberration by using a low dispersion material.

  When the lower limit of conditional expression (6) is exceeded, the optical material of the positive lens LR1p becomes too highly dispersed, making it difficult to correct chromatic aberration in the entire optical system. On the other hand, if the upper limit is exceeded, the optical material of the positive lens LR1p becomes too low dispersion. In addition, since the optical material existing in the region exceeding the upper limit of the conditional expression has a low refractive index, the amount of spherical aberration generated in the positive lens LR1p increases, and it becomes difficult to correct spherical aberration in the entire optical system.

  Conditional expression (7) is a conditional expression that defines the Abbe number of the optical material of the biconcave negative lens LR3n arranged closest to the image side in the rear group GR. The negative lens LR3n shares the role of correcting spherical aberration and chromatic aberration in the rear group GR, and corrects spherical aberration and chromatic aberration well in the GR group by using a high dispersion material.

  When the lower limit of conditional expression (7) is exceeded, the optical material of the negative lens LR3n becomes too highly dispersed, and chromatic aberration is overcorrected in the entire optical system. On the other hand, if the upper limit is exceeded, the optical material of the negative lens LR3n becomes too low in dispersion, and a strong refractive power is disposed for correcting chromatic aberration. At this time, spherical aberration is excessively corrected in the GR group, and it is difficult to achieve both aberration correction and chromatic aberration.

  In each embodiment, the numerical ranges of conditional expressions (3) to (7) are more preferably set to the following ranges.

−0.8 <fR1p / fR23 <0.0 (3a)
−0.6 <(RR3b + RR3a) / (RR3b−RR3a) <0.8
... (4a)
−0.35 <fFn / fFp <−0.7 (5a)
52.0 <νdR1p <90.0 (6a)
13.0 <νdR3n <24.0 (7a)
In each embodiment, it is more preferable that the numerical ranges of the conditional expressions (3a) to (7a) are set to the following ranges.

−0.6 <fR1p / fR23 <0.0 (3b)
−0.5 <(RR3b + RR3a) / (RR3b−RR3a) <0.7
... (4b)
−0.4 <fFn / fFp <−0.6 (5b)
54.0 <νdR1p <85.0 (6b)
16.0 <νdR3n <23.0 (7b)
[Example 1]
Hereinafter, an optical system according to Example 1 of the present invention will be described with reference to FIG.

  The first exemplary embodiment includes, in order from the object side to the image side, a front group GF, an aperture stop SS, and a rear group GR. The front group GF is composed of a negative refractive power subgroup GFn and a negative refractive power subgroup GFp in order from the object side to the image side. Further, the sub-group GFn having a negative refractive power has a meniscus negative lens having a convex surface facing the object side closest to the object side. The rear group GR is composed of a biconvex positive lens LR1p, a positive lens LR2p, and a biconcave negative lens LR3n in order from the object side to the image side.

  Specifically, the negative subgroup GFn constituting the front group GF is composed of a meniscus negative lens having a convex surface facing the object side and a biconcave lens in order from the object side to the image side. Further, the positive subgroup GFp constituting the front group GF is constituted by one biconvex positive lens. The rear group GR is composed of a total of three lenses, in which a positive lens LR2p and a biconcave negative lens LR3n are cemented.

  The front group GF shares the function of a wide converter that captures a wide angle of view as a substantially afocal configuration that satisfies the conditional expression (1). Further, the rear group GR becomes a converging master group, and the positive lens LR1p in the group has a shape that satisfies the conditional expression (2), and corrects spherical aberration well. With this configuration, a compact imaging optical system having a good optical performance in the entire optical system, a wide field angle, a large aperture, and a small size is realized.

  Further, negative distortion is appropriately left in the entire optical system. As a result, the half angle of view of the optical system in an ideal imaging state that does not take distortion into consideration is 48 degrees, but in the actual ray tracing that takes distortion into consideration, a light beam exceeding the half angle of view of 52 degrees forms an image on the imaging surface. In addition, the wide angle of view of the optical system is realized without increasing the size of the optical system.

[Example 2]
Hereinafter, an optical system according to Example 2 of the present invention will be described with reference to FIG. The configuration of the optical system of Example 2 is the same as that of Example 1.

  Example 2 is different from Example 1 in that the aperture of the optical system is increased.

[Example 3]
Hereinafter, an optical system according to Example 3 of the present invention will be described with reference to FIG. The configuration of the optical system of Example 3 is the same as that of Example 1.

  The third embodiment is different from the first embodiment in that the remaining amount of negative distortion is increased and the entire optical system is downsized.

[Example 4]
Hereinafter, an optical system according to Example 4 of the present invention will be described with reference to FIG. The configuration of the optical system of Example 4 is the same as that of Example 3.

  Example 4 is different from Example 3 in that the lens shape and the optical material are changed.

[Example 5]
Hereinafter, an optical system according to Example 5 of the present invention will be described with reference to FIG. The basic configuration of the optical system of the fifth embodiment is the same as that of the first embodiment.

  Example 5 is different from Example 1 in that the configuration of the front group GF is changed.

  Specifically, the negative subgroup GFn constituting the front group GF is constituted by a single meniscus negative lens having a convex surface facing the object side. The positive subgroup GFp constituting the front group GF is constituted by one meniscus positive lens having a convex surface facing the image side.

  The number of components of the optical system is reduced, and the optical system and the lens barrel are simplified.

  Here, focusing on a short-distance object can be applied to not only the entire focus that moves the entire optical system to the object side, but also the partial focus that moves a part of the optical system. In addition, when correcting camera shake, various known methods such as a configuration in which the entire optical system or a part thereof is displaced, and a configuration in which the image sensor is displaced may be applied.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

  Next, numerical examples of the present invention will be shown. In each numerical example, i indicates the order of the surfaces from the object side, and ri is the radius of curvature of the lens surface. di is a lens thickness and an air space between the i-th surface and the (i + 1) -th surface. ndi and νdi denote the refractive index and Abbe number for the d-line, respectively. * Indicates an aspherical surface. K, A4, A6, A8, and A10 are aspherical coefficients.

In the aspherical shape, x = (h ² / R) / [1+ {1− (1 + k) (h) where x is the displacement in the optical axis direction at the position of height h from the optical axis with respect to the surface vertex. / R) ² } ^1/2 ] + A4 · h ⁴ + A6 · h ⁶ + A8 · h ⁸ + A10 · h ¹⁰
It is represented by Where R is the paraxial radius of curvature.

  Note that the back focus BF is expressed as a distance from the final surface. Table 1 shows the relationship between the above-described conditional expressions and numerical examples.

(Numerical example 1)
Unit mm

Surface data surface number rd nd vd Effective diameter
1 7.099 0.60 1.55332 71.7 7.85
2 * 2.403 2.64 5.17
3 -7.395 0.60 1.69895 30.1 4.72
4 8.594 0.71 4.33
5 * 13.494 2.40 1.81000 41.0 4.24
6 -5.913 1.60 3.93
7 (Aperture) ∞ 1.45 3.62
8 * 8.053 2.80 1.59201 67.0 3.68
9 * -3.632 0.19 4.42
10 274.504 2.20 1.83400 37.2 4.36
11 -3.646 0.60 1.92286 20.9 4.29
12 * 16.248 1.68 4.33
13 ∞ 1.05 1.51633 64.1 8.00
14 ∞ 0.50 8.00
Image plane ∞

Aspheric data 2nd surface
K = -3.24137e-001 A 4 = 1.72497e-004 A 6 = -1.06680e-006

5th page
K = 0.00000e + 000 A 4 = -2.00701e-003 A 6 = -5.00006e-006

8th page
K = 0.00000e + 000 A 4 = -1.36219e-003 A 6 = -1.16243e-004 A 8 = -3.92404e-005

9th page
K = 0.00000e + 000 A 4 = 5.37246e-003 A 6 = -2.93638e-004

12th page
K = 0.00000e + 000 A 4 = -3.87267e-005 A 6 = 5.27490e-004 A 8 = 8.36625e-007

Various data

Focal length 2.70
F number 1.64
Angle of view 48.01
Statue height 3.00
Total lens length 19.01
BF 0.50

Entrance pupil position 3.60
Exit pupil position -7.76
Front principal point position 5.41
Rear principal point position -2.21

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
GF 1 740.55 6.95 392.55 820.86
SS 7 ∞
GR 8 5.70 5.79 0.32 -2.82
G 13 ∞ 1.05

Single lens Data lens Start surface Focal length
1 1 -6.88
2 3 -5.60
3 5 5.37
LR1p 8 4.64
LR2p 10 4.33
LR3n 11 -3.18

(Numerical example 2)
Unit mm

Surface data surface number rd nd vd Effective diameter
1 7.088 0.60 1.55332 71.7 8.96
2 * 2.745 2.86 5.99
3 -23.640 0.60 1.69895 30.1 5.56
4 4.960 1.16 4.81
5 * 9.172 2.50 1.81000 41.0 4.66
6 -8.098 1.75 4.10
7 (Aperture) ∞ 1.30 4.16
8 * 10.438 2.70 1.55332 71.7 4.20
9 * -4.970 0.10 4.41
10 * 8.312 1.90 1.81000 41.0 4.60
11 -5.940 0.60 1.92286 18.9 4.55
12 9.757 1.89 4.57
13 ∞ 1.05 1.51633 64.1 8.00
14 ∞ 0.50 8.00
Image plane ∞

Aspheric data 2nd surface
K = -2.91266e-001 A 4 = 7.27613e-005 A 6 = 1.49120e-005

5th page
K = 0.00000e + 000 A 4 = -1.16101e-003 A 6 = 7.81714e-006

8th page
K = 0.00000e + 000 A 4 = 7.16181e-004 A 6 = -7.18229e-005 A 8 = -1.21930e-005

9th page
K = 0.00000e + 000 A 4 = 1.52635e-003 A 6 = -1.07478e-004

10th page
K = 0.00000e + 000 A 4 = -1.16826e-003 A 6 = -1.57627e-004

Various data

Focal length 2.78
F number 1.44
Angle of view 47.18
Statue height 3.00
Total lens length 19.51
BF 0.50

Entrance pupil position 4.15
Exit pupil position -7.46
Front principal point position 5.96
Rear principal point position -2.29

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
GF 1 92.77 7.72 50.77 95.45
SS 7 ∞
GR 8 5.71 5.30 0.40 -2.47
G 13 ∞ 1.05

Single lens Data lens Start surface Focal length
1 1 -8.51
2 3 -5.82
3 5 5.68
LR1p 8 6.49
LR2p 10 4.55
LR3n 11 -3.93

(Numerical Example 3)
Unit mm

Surface data surface number rd nd vd Effective diameter
1 14.677 0.60 1.74330 49.3 7.40
2 * 2.516 1.79 4.93
3 -48.838 0.60 1.69895 30.1 4.80
4 8.487 0.12 4.50
5 * 8.119 2.50 1.81000 41.0 4.49
6 -7.079 1.50 4.00
7 (Aperture) ∞ 1.30 3.37
8 * 10.527 2.00 1.67790 54.9 3.48
9 * -4.835 0.20 4.10
10 * 8.446 1.50 1.81000 41.0 4.25
11 -5.862 0.60 1.92286 18.9 4.22
12 7.598 1.94 4.24
13 ∞ 1.05 1.51633 64.1 8.00
14 ∞ 0.50 8.00
Image plane ∞

Aspheric data 2nd surface
K = -3.47275e-001 A 4 = 3.11351e-004 A 6 = 9.25723e-005

5th page
K = 0.00000e + 000 A 4 = -2.32486e-003 A 6 = -1.03847e-005

8th page
K = 0.00000e + 000 A 4 = 1.14835e-003 A 6 = -1.14219e-005 A 8 = -3.25952e-005

9th page
K = 0.00000e + 000 A 4 = 3.27144e-003 A 6 = -3.23771e-004

10th page
K = 0.00000e + 000 A 4 = -5.59573e-004 A 6 = -4.01063e-004

Various data

Focal length 2.78
F number 1.65
Angle of view 47.18
Statue height 3.00
Total lens length 16.20
BF 0.50

Entrance pupil position 2.76
Exit pupil position -6.53
Front principal point position 4.44
Rear principal point position -2.29

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
GF 1 -62.58 5.61 -26.68 -54.09
SS 7 ∞
GR 8 5.08 4.30 -0.02 -2.19
G 13 ∞ 1.05

Single lens Data lens Start surface Focal length
1 1 -4.17
2 3 -10.30
3 5 5.04
LR1p 8 5.16
LR2p 10 4.48
LR3n 11 -3.51

(Numerical example 4)
Unit mm

Surface data surface number rd nd vd Effective diameter
1 19.223 0.60 1.76802 49.2 7.66
2 * 2.592 1.92 5.14
3 -54.048 0.60 1.76182 26.5 4.98
4 8.053 0.25 4.72
5 * 5.895 2.65 1.85400 40.4 4.72
6 -9.009 1.55 4.16
7 (Aperture) ∞ 1.20 3.43
8 * 8.656 2.00 1.67790 54.9 3.46
9 * -5.392 0.33 4.03
10 * 11.207 1.40 1.85400 40.4 4.20
11 -6.224 0.60 1.95906 17.5 4.22
12 9.278 1.85 4.29
13 ∞ 1.05 1.51633 64.1 8.00
14 ∞ 0.50 8.00
Image plane ∞

Aspheric data 2nd surface
K = -3.79407e-001 A 4 = -8.06802e-005 A 6 = 2.60618e-005

5th page
K = 0.00000e + 000 A 4 = -2.22215e-003 A 6 = -1.44823e-005

8th page
K = 0.00000e + 000 A 4 = 1.71623e-004 A 6 = 5.28095e-005 A 8 = -2.48694e-005

9th page
K = 0.00000e + 000 A 4 = 2.56868e-003 A 6 = -1.74638e-004

10th page
K = 0.00000e + 000 A 4 = -1.00608e-003 A 6 = -2.25666e-004

Various data

Focal length 2.78
F number 1.65
Angle of view 47.18
Statue height 3.00
Total lens length 16.50
BF 0.50

Entrance pupil position 2.77
Exit pupil position -6.32
Front principal point position 4.42
Rear principal point position -2.29

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
GF 1 343.06 6.01 167.07 316.85
SS 7 ∞
GR 8 5.37 4.33 -0.03 -2.29
G 13 ∞ 1.05

Single lens Data lens Start surface Focal length
1 1 -3.96
2 3 -9.16
3 5 4.54
LR1p 8 5.20
LR2p 10 4.87
LR3n 11 -3.81

(Numerical example 5)
Unit mm

Surface data surface number rd nd vd Effective diameter
1 11.692 0.60 1.85135 40.1 8.47
2 * 3.406 4.91 5.88
3 -125.709 1.35 1.88300 40.8 4.63
4 -11.403 1.50 4.41
5 (Aperture) ∞ 1.20 3.05
6 * 4.885 2.65 1.55332 71.7 3.54
7 * -5.235 0.10 4.11
8 * 5.326 1.25 1.76802 49.2 4.05
9 -8.054 0.60 1.80809 22.8 3.89
10 3.102 1.79 3.59
11 ∞ 1.05 1.51633 64.1 8.00
12 ∞ 0.50 8.00
Image plane ∞

Aspheric data 2nd surface
K = 0.00000e + 000 A 4 = 9.98111e-004 A 6 = 2.51293e-006 A 8 = 1.22071e-005

6th page
K = 0.00000e + 000 A 4 = -3.94024e-004 A 6 = -3.84531e-004 A 8 = -1.78025e-005

7th page
K = 0.00000e + 000 A 4 = 1.12369e-003 A 6 = -5.15237e-004

8th page
K = 0.00000e + 000 A 4 = -2.33210e-003 A 6 = -5.95313e-004

Various data

Focal length 2.90
F number 1.95
Angle of view 45.97
Statue height 3.00
Total lens length 17.50
BF 0.50

Entrance pupil position 3.69
Exit pupil position -5.51
Front principal point 5.19
Rear principal point position -2.41

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -30.30 6.86 -11.46 -28.78
2 5 ∞
3 6 5.31 4.60 -1.02 -2.85
4 11 ∞ 1.05

Single lens Data lens Start surface Focal length
1 1 -5.84
2 3 14.12
LR1p 6 5.04
LR2p 8 4.35
LR3n 9 -2.71

GF front group, GR rear group, negative partial lens group in GFn front group,
Positive partial lens group in the front group of GFp,
LR1p A biconvex positive lens disposed closest to the object side in the rear group,
LR2p A positive lens arranged second from the object side in the rear group,
LR3n Biconcave negative lens arranged most on the image side in the rear group, G glass block,
SS Aperture stop, IP image plane

Claims (9)

A front group aperture stop that is arranged on the object side from the aperture stop in order from the object side to the image side is configured by a rear group that is arranged on the image side from the aperture stop. A negative lens having a meniscus shape with a convex surface facing, a sub-group having a negative refractive power and a positive refractive power sub-group, the rear group being a biconvex positive lens in order from the object side. An imaging optical system comprising a lens and satisfying the following conditional expression:
-0.2 <fA / fF <0.2 (1)
−0.5 <(RR1b + Rr1a) / (RR1b−Rr1a) <0.2
... (2)
here,
fA is the focal length fF of the entire optical system, the focal length RR1b of the front group is the radius of curvature RR1a on the image side surface of the biconvex positive lens disposed closest to the object side in the rear group, Radius of curvature on the object side of a biconvex positive lens placed closest to the object side in the group The imaging optical system according to claim 1, wherein the following conditional expression is satisfied.
-1.0 <fR1p / fR23 <0.0 (3)
here,
fR1p is a focal length fR23 of the biconvex positive lens disposed on the most object side in the rear group, and fR1p is a positive lens and a biconcave negative lens disposed on the image side of the biconvex positive lens. Composite focal length The imaging optical system according to claim 1, wherein the following conditional expression is satisfied.
−0.7 <(RR3b + RR3a) / (RR3b−RR3a) <0.9
(4)
here,
RR3b is a radius of curvature RR3a on the image side surface of the biconcave negative lens disposed closest to the image side of the rear group, and RR3a is on the object side surface of the biconcave positive lens disposed closest to the image side of the rear group. curvature radius The imaging optical system according to claim 1, wherein the following conditional expression is satisfied.
−0.8 <fFn / fFp <−0.3 (5)
here,
fFn is the focal length of the negative refractive power subgroup arranged in the front group, and fFp is the focal length of the positive refractive power subgroup arranged in the front group. The imaging optical system according to any one of claims 1 to 4, wherein the following conditional expression is satisfied.
50.0 <νdR1p <100.0 (6)
here,
νdR1p is the Abbe number of the optical material of the biconvex positive lens disposed on the most object side in the rear group The imaging optical system according to any one of claims 1 to 5, wherein the following conditional expression is satisfied.
10.0 <νdR3n <25.0 (7)
here,
νdR3n is the Abbe number of the optical material of the biconcave negative lens arranged on the most image side of the rear group The imaging optical system according to claim 1, wherein the negative refractive power subgroup disposed in the front group includes only a negative lens. The imaging optical system according to claim 7, wherein the sub-group having a negative refractive power disposed in the front group includes two lenses. The imaging optical system according to any one of claims 1 to 7, wherein the positive refractive power subgroup disposed in the front group includes a single positive lens.