JP2020042221A - Wide-angle lens system - Google Patents

Abstract

To provide a wide-angle lens system which is configured to suppress both image height variation during wobbling and aberration variation due to change in in-focus position through appropriate placement of a focusing group.SOLUTION: A wide-angle lens system disclosed herein comprises a first lens group G1 having negative refractive power and a succeeding lens group GR having positive refractive power as a whole, where the succeeding lens group GR comprises an aperture stop S, a front-side lens group GP disposed on the object side of the aperture stop, and a focusing lens group GF disposed on the object side of the front-side lens group GP and configured to move for focusing, the front-side lens group GP and the focusing lens group GF having positive refractive power. When zooming from the wide-angle end to the telephoto end, at least an air gap distance between the first lens group G1 and the succeeding lens group GR narrows. The wide-angle lens system satisfies specific conditional expressions.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical system suitable for a photographing lens used in an image pickup apparatus such as a still camera and a video camera, employs an inner focus method suitable for an autofocus camera, and slightly oscillates a focus lens group in a direction along an optical axis. The present invention relates to a wide-angle lens system in which changes in various aberrations such as astigmatism and chromatic aberration of magnification due to a change in an in-focus position are suppressed while suppressing a change rate of an image height when the image is changed.

  In recent years, with the increase in the number of pixels of a digital camera or the like, it has been required to strictly correct various aberrations in an optical system used.

  In addition, like the autofocus of a mirrorless single-lens camera that has recently emerged, the focus lens group is continuously vibrated in the direction along the optical axis (hereinafter referred to as wobbling), so that the focus driving direction is always determined. A type of inner focus method has been developed. At this time, if the image height change rate during wobbling is large, the viewer perceives the change in magnification of the subject reflected on the screen, and feels obstructive. Therefore, a focus type in which the image height change rate is small with respect to the focus change is desired.

  However, in the conventionally proposed optical system in which the rate of change in image height during wobbling is suppressed, fluctuations in various aberrations such as astigmatism and chromatic aberration due to a change in the focusing position are large, so that the near-infinity focusing from infinity focusing takes place. It has been difficult to maintain good imaging performance up to the time of distance focusing.

  Patent Document 1 or Patent Document 2 is disclosed as an example of the patent document relating to the above.

JP 2015-166834 A International Publication No. 2015-178095

  Patent Document 1 proposes a variable power optical system that suppresses the image height change rate when the focus lens group is wobbled while having a wide angle of view. However, the variable power optical system disclosed in Patent Document 1 has a large variation in spherical aberration and longitudinal chromatic aberration due to a change in focus position. Therefore, the same optical system configuration is applied to an optical system having an aperture larger than about F4.0. It is difficult.

  Patent Literature 2 proposes a variable power optical system that has a wide angle of view and suppresses a variation in aberration due to a change in focus position. However, the variable power optical system disclosed in Patent Document 2 has a large image height variation when the focus lens group is wobbled.

  SUMMARY OF THE INVENTION It is an object of the present invention to provide a wide-angle lens system in which by appropriately arranging a focus lens group, both an image height variation during wobbling and a variation in aberration due to a change in a focus position are suppressed.

According to a first aspect of the present invention, there is provided, in order from the object side, a first lens group G1 having a negative refractive power and a subsequent lens group GR having a positive refractive power as a whole. The subsequent lens group GR includes an aperture stop S, a front lens group GP on the object side, and a focusing lens group GF that moves to the object side for focusing. The focal lens group GF has a positive refractive power, and at the time of zooming from the wide-angle end to the telephoto end, at least the air gap between the first lens group G1 and the subsequent lens group GR decreases, and the following conditional expression is satisfied. A wide-angle lens system.
(1) 0.28 <DPS / HIM <1.00
However,
DPS: distance on the optical axis from the most image side surface of the front lens group GP of the diaphragm to the aperture stop S at the time of focusing on an object at infinity at the wide angle end HIM: maximum image height at the time of focusing on an object at infinity at the wide angle end

According to a second aspect of the present invention, there is provided a wide-angle lens system according to the first aspect, further satisfying the following conditional expression.
(2) −1.00 <MRW ＾ 2 × (1−MFW ＾ 2) <− 0.30
However,
MFW: lateral magnification of the focusing lens group GF when focusing on an object at infinity at the wide-angle end MRW: composite lateral magnification from the front lens group GP on the focusing side to an optical surface closest to the image side when focusing on an object at infinity at the wide-angle end

A third invention is a wide-angle lens system according to the first or second invention, further satisfying the following conditional expression.
(3) 0.10 <√ (fw × ft) / fF <0.50
(4) 0.04 <√ (fw × ft) / fP <0.20
However,
fw: focal length ft of the entire lens system at infinity shooting at the wide-angle end ft: focal length fF of the entire lens system at infinity shooting at the telephoto end fF: focal length fP of the focusing lens group GF: the front lens group of the diaphragm GP focal length

  In a fourth aspect based on any of the first to third aspects, the first lens group G1 further comprises four or more lenses having negative refractive power, and three or more of the lenses have an object side. This is a wide-angle lens system characterized by being a meniscus lens having a convex surface facing the lens.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the following lens group GR has a cemented surface facing a convex surface on the object side, and a refractive index of a medium on the object side is smaller than an image. A wide-angle lens system comprising four or more sets of cemented lenses each having a refractive index higher than the refractive index of the medium on the surface side.

  A sixth aspect of the present invention is the wide-angle lens system according to any one of the first to fifth aspects, wherein the subsequent lens group GR has an aspheric surface at a lens closest to the image plane. .

  According to the present invention, it is possible to provide a wide-angle lens system in which both the fluctuation of the image height at the time of wobbling and the fluctuation of the aberration due to the change of the focus position are suppressed by appropriately arranging the focus groups.

FIG. 3 is a lens configuration diagram of the zoom optical system according to the first embodiment at infinity at the wide-angle end. Longitudinal aberration diagram at infinity at the wide-angle end of the variable power optical system of the first embodiment Longitudinal aberration diagram at infinity of the intermediate focal length of the variable power optical system of the first embodiment Longitudinal aberration diagram of the variable power optical system according to the first embodiment at infinity at the telephoto end. Lateral aberration diagram at infinity at the wide-angle end of the variable power optical system of the first embodiment Lateral aberration diagram of the variable power optical system of the first embodiment at infinity at an intermediate focal length. Lateral aberration diagram at infinity at the telephoto end of the variable power optical system of Embodiment 1. FIG. 4 is a lens configuration diagram of a zoom optical system according to a second embodiment at infinity at the wide-angle end. Longitudinal aberration diagram at infinity at the wide-angle end of the variable power optical system of the second embodiment Longitudinal aberration diagram of the variable power optical system according to the second embodiment at infinity at an intermediate focal length. Longitudinal aberration diagram at infinity at the telephoto end of the variable power optical system of Embodiment 2. Lateral aberration diagram of the variable power optical system of the second embodiment at infinity at the wide-angle end. Lateral aberration diagram of the variable power optical system of the second embodiment at infinity at an intermediate focal length. Lateral aberration diagram of the variable power optical system according to the second embodiment at infinity at the telephoto end. FIG. 9 is a lens configuration diagram of a zoom optical system according to a third embodiment at infinity at the wide-angle end. Longitudinal aberration diagram at infinity at the wide-angle end of the variable power optical system of the third embodiment Longitudinal aberration diagram at infinity of the intermediate focal length of the variable power optical system of the third embodiment Longitudinal aberration diagram at infinity at the telephoto end of the variable power optical system according to the third embodiment. Lateral aberration diagram at infinity at the wide-angle end of the variable power optical system of the third embodiment Lateral aberration diagram of the variable power optical system of the third embodiment at infinity at an intermediate focal length. Lateral aberration diagram of the variable power optical system of the third embodiment at infinity at the telephoto end. FIG. 7 is a lens configuration diagram of a zoom optical system according to a fourth embodiment at infinity at the wide-angle end. Longitudinal aberration diagram of the variable power optical system of the fourth embodiment at infinity at the wide-angle end. Longitudinal aberration diagram at infinity of the intermediate focal length of the variable power optical system according to the fourth embodiment. Longitudinal aberration diagram at infinity at the telephoto end of the variable power optical system of Example 4. Lateral aberration diagram of the variable power optical system of the fourth embodiment at infinity at the wide-angle end. Lateral aberration diagram of the variable power optical system of the fourth embodiment at infinity at an intermediate focal length. Lateral aberration diagram of the variable power optical system of the fourth embodiment at infinity at the telephoto end. FIG. 7 is a lens configuration diagram of a zoom optical system according to a fifth embodiment at infinity at the wide-angle end. Longitudinal aberration diagram of the variable power optical system of the fifth embodiment at infinity at the wide-angle end. Longitudinal aberration diagram at infinity of the intermediate focal length of the variable power optical system of Embodiment 5. Longitudinal aberration diagram at infinity at the telephoto end of the variable power optical system of Example 5. Lateral aberration diagram of the variable power optical system of the fifth embodiment at infinity at the wide-angle end. Lateral aberration diagram at infinity of the intermediate focal length of the variable power optical system of Embodiment 5. Lateral aberration diagram of the variable power optical system of the fifth embodiment at infinity at the telephoto end.

  Hereinafter, embodiments of the optical system according to the present invention will be described in detail. The following description of an embodiment is an example of the wide-angle lens system of the present invention, and the present invention is not limited to the present embodiment without departing from the gist of the present invention.

  As can be seen from the lens configuration diagrams shown in FIGS. 1, 8, 15, 22, and 29, the wide-angle lens system according to the present invention includes, in order from the object side, a first lens group G1 having a negative refractive power and a whole. The subsequent lens group GR has a positive refractive power. The subsequent lens group GR has an aperture stop S, a front lens group GP on the object side thereof, and a focusing lens which moves upon focusing on the object side. A lens group GF, wherein the aperture front lens group GP and the focusing lens group GF have a positive refractive power, and at the time of zooming from the wide-angle end to the telephoto end, at least the first lens group G1 and the subsequent The air gap between the lens groups GR is reduced.

  An object of the present invention is to provide a wide-angle lens system in which both fluctuations in image height during wobbling and fluctuations in aberration due to a change in focus position are suppressed, and when the focus lens group GF moves along the optical axis. It is important to appropriately correct the change in the aberration coefficient.

  By forming the image of the aperture stop S as viewed from the focusing lens group GF in a distant place, it becomes possible to make the image height fluctuation at the time of wobbling minute. In order to form an image of the aperture stop S viewed from the focusing lens group GF in a distant place, the distance between the focusing lens group GF and the aperture stop S is increased or the positive It is advantageous to increase the refractive power, but in any case, the aberration generated in the focusing lens group GF is deteriorated, and the fluctuation of the aberration due to a change in the focusing position is increased.

  Thus, by disposing the front lens group GP having a positive refractive power between the focusing lens group GF and the aperture stop S, the distance between the focusing lens group GF and the aperture stop and the focusing lens group An image of the aperture stop S viewed from the focusing lens group GF can be formed at a long distance while suppressing the positive refractive power of the GF.

  Here, by forming and projecting the image of the aperture stop S viewed from the focusing lens group GF at a distance, and by defining the lateral magnification of the focusing lens group GF and the composite lateral magnification of the subsequent lens groups, The reason why the image height fluctuation at the time of wobbling can be reduced is as follows.

The image height variation due to the wobbling can be represented by the variation in distortion due to the wobbling. According to Yoshiya Matsui, Lens Design Method, Kyoritsu Shuppan P88, the third-order distortion aberration coefficient V is represented by the following reference formula (1).
V = JIV
This is expanded as follows, and the third-order distortion aberration coefficient V is proportional to the cube of the paraxial principal ray height H ′.
Reference formula (1) V = ((H ′ · Q ′) ＾ 3 / (H · Q)) · H ＾ 2 · Δ (1 / (n · s)) + P · (H ′ · Q ′) / ( H ・ Q)

Thus, in order to reduce the fluctuation of the distortion due to the wobbling, the fluctuation of the paraxial chief ray height of the focusing lens unit due to the wobbling may be reduced. Here, with reference to the object-side surface of the focusing lens unit GF at the infinite object distance, the position of the image of the aperture stop by the front lens unit GP, the lateral magnification of the focusing lens unit GF, and the focusing lens Variation Δh of the principal ray height of the focusing lens group due to wobbling based on the combined lateral magnification from the aperture front lens group GP, which is a lens group behind the group, to the optical surface closest to the image, and the principal ray height in the focusing lens group. Is represented by the following reference formula (2).
Reference formula (2) Δh = h′−h = h · Δs / (FcEntp × MR ＾ 2 × (1-MF ＾ 2))
However,
FcEntp: Image position Δs of the stop by the synthetic optical system of the surface from the focusing lens group GF at the wide-angle end to the front of the stop at infinity of the object distance. Principal ray height h 'in the focusing lens group: Principal ray height MF in the focusing lens group at wobbling: Lateral magnification MR of the focusing lens group GF at the time of focusing on an object at infinity: The stop at the time of focusing on an object at infinity Composite lateral magnification from the front lens group GP to the optical surface closest to the image side

Further, the wide-angle lens system according to the present invention is characterized by further satisfying the following conditional expression.
(1) 0.28 <DPS / HIM <1.00
DPS: distance on the optical axis from the most image side surface of the front lens group GP of the diaphragm to the aperture stop S at the time of focusing on an object at infinity at the wide angle end HIM: maximum image height at the time of focusing on an object at infinity at the wide angle end

  Conditional expression (1) defines a preferable range for the distance between the aperture front lens group GP and the aperture stop S when focusing on an object at infinity at the wide-angle end.

  If the lower limit of conditional expression (1) is exceeded and the distance on the optical axis from the most image-side surface of the front lens group GP of the diaphragm to the aperture stop S at the time of focusing on an object at infinity at the wide-angle end becomes smaller, It becomes difficult to form an image of the aperture stop S as viewed from the focusing lens group GF in a distant position while suppressing the refractive power of the lens group GF. It becomes impossible to suppress both fluctuations.

  When the value exceeds the upper limit of conditional expression (1) and the distance on the optical axis from the most image-side surface of the front lens group GP of the diaphragm to the aperture stop S at the time of focusing on an object at infinity at the wide-angle end increases, the focusing is performed. The height of the principal ray in the lens group GF becomes high, and it becomes difficult to suppress the fluctuation of aberration due to the change of the focusing position. In addition, the diameter of the lens constituting the focusing lens group GF increases, and focusing and wobbling become difficult. In this case, it is difficult to reduce the weight of the driving part.

  By setting the lower limit of conditional expression (1) to 0.32, the effects of the present invention can be more reliably achieved. By setting the upper limit of conditional expression (1) to 0.80, the effects of the present invention can be more reliably achieved.

It is desirable that the wide-angle lens system of the present invention further satisfies the following conditional expressions.
(2) −1.00 <MRW ＾ 2 × (1−MFW ＾ 2) <− 0.30
MFW: lateral magnification of the focusing lens group GF when focusing on an object at infinity at the wide-angle end MRW: composite lateral magnification from the front lens group GP on the focusing side to an optical surface closest to the image side when focusing on an object at infinity at the wide-angle end

  Conditional expression (2) defines a preferable range for the sensitivity of the imaging surface when the focusing lens unit GF moves when focusing on an object at infinity at the wide-angle end.

  When the lower limit of conditional expression (2) is exceeded and the sensitivity of the imaging surface when the focusing lens unit GF moves during focusing on an object at infinity at the wide-angle end increases, the moving amount of the focusing lens unit decreases. Therefore, the imaging surface largely moves due to the slight movement of the focusing lens group, and it becomes difficult to drive and control the focusing lens group GF within the AF focusing range.

  If the upper limit of conditional expression (2) is exceeded and the sensitivity of the imaging surface when the focusing lens group GF moves during focusing on an object at infinity at the wide-angle end decreases, the amount of movement of the focusing group increases. Since the fluctuation Δh of the principal ray height of the focusing lens unit due to the wobbling becomes large, the effect of suppressing the fluctuation of the image height becomes weak, and it becomes difficult to suppress the fluctuation of the image height during the wobbling. Further, a space before and after the focusing lens group GF must be secured, and it is difficult to make the optical system compact.

  By setting the lower limit of conditional expression (2) to -0.80, the effects of the present invention can be more reliably achieved. By setting the upper limit of conditional expression (2) to -0.40, the effects of the present invention can be more reliably achieved.

It is desirable that the wide-angle lens system of the present invention further satisfies the following conditional expressions.
(3) 0.10 <√ (fw × ft) / fF <0.50
(4) 0.04 <√ (fw × ft) / fP <0.20
fw: focal length ft of the entire lens system at infinity shooting at the wide-angle end ft: focal length fF of the entire lens system at infinity shooting at the telephoto end fF: focal length fP of the focusing lens group GF: the front lens group of the diaphragm GP focal length

  Conditional expression (3) defines a preferable range of the refractive power of the focusing lens unit GF.

  Conditional expression (4) defines a preferable range of the refractive power of the front lens group GP on the stop side.

  If the upper limit of conditional expression (3) is exceeded and the refractive power of the focusing lens group GF is increased, the fluctuation of the paraxial chief ray height in the group closer to the object side than the focusing lens group due to wobbling increases, and Since the aberration occurring in the focusing lens group GF itself is also deteriorated, it becomes difficult to suppress both the fluctuation of the image height at the time of wobbling and the fluctuation of the aberration due to the change of the focus position.

  If the lower limit value of the conditional expression (3) is exceeded and the refractive power of the focusing lens unit GF is weakened, the sensitivity of the imaging surface when the focusing lens unit moves is reduced. It is difficult to keep the upper limit from being exceeded.

  By setting the lower limit of conditional expression (3) to 0.15, the effects of the present invention can be more reliably achieved. By setting the upper limit of conditional expression (3) to 0.40, the effects of the present invention can be more reliably achieved.

  When the value exceeds the upper limit of conditional expression (4) and the refractive power of the front lens group GP on the diaphragm side is increased, it is necessary to increase the negative refractive power of the first lens group G1 in order to maintain a wide angle of view. And it becomes difficult to suppress the aberration generated in the first lens group G1.

  If the lower limit of conditional expression (4) is exceeded and the refractive power of the front lens group GP becomes weak, the distance between the focusing lens group GF and the aperture stop and the positive refractive power of the focusing lens group GF are suppressed. On the other hand, it is difficult to form an image of the aperture stop as viewed from the focusing lens group GF in a distant place.

  By setting the lower limit of conditional expression (4) to 0.05, the effects of the present invention can be more reliably achieved. By setting the upper limit of conditional expression (4) to 0.15, the effects of the present invention can be more reliably achieved.

  In the wide-angle lens system according to the present invention, the first lens group G1 has four or more lenses having negative refractive power, and at least three of them have a meniscus having a surface having positive refractive power facing the object side. Preferably, it is a lens.

  Since the first lens group G1 has four or more lenses having negative refractive power, it becomes easy to maintain a necessary back focus while maintaining a wide angle of view. In addition, since at least three of the lenses having the negative refractive power are meniscus lenses having a convex surface facing the object side, the declination between the entrance surface and the exit surface with respect to a ray incident on the peripheral image height is reduced. And it is easy to suppress the deterioration of distortion due to the surface having a negative refractive power.

  Also, in the wide-angle lens system according to the present invention, the following lens group GR may be configured such that the cemented surface is convex toward the object side and the refractive index of the medium on the object side is higher than the refractive index of the medium on the image side. It is desirable to have four or more lenses.

  If the number of cemented lenses whose convex surface faces the object side and the refractive index of the medium on the object side is higher than the refractive index of the medium on the image plane side is three or less, the coma aberration is directed to the subsequent lens group GR. If one of the spherical aberration is corrected, it becomes difficult to correct the other. However, by arranging four or more such cemented lenses, it becomes easy to correct coma and spherical aberration in a well-balanced manner.

  In the wide-angle lens system according to the present invention, it is preferable that the lens closest to the image plane in the subsequent lens group GR has an aspheric surface.

  By arranging an aspherical surface on the lens closest to the image plane of the subsequent lens group GR, it is easy to give an effect on the peripheral light beam while suppressing the effect of the aspherical surface on the axial light beam, and to affect the spherical aberration. It is easy to correct coma and astigmatism while suppressing the aberration.

  Next, a description will be given of a lens configuration, a numerical example, and a conditional expression corresponding value of an embodiment according to the wide-angle lens system of the present invention. In the following description, the lens configuration is described in order from the object side to the image plane side. The notation Ln in the examples indicates the n-th lens from the object side.

  In [surface data], the surface number is the number of the lens surface or the aperture stop counted from the object side, r is the radius of curvature of each lens surface, d is the distance between each lens surface, and nd is the d-line (wavelength 587.56 nm). Refractive index, vd indicates Abbe number with respect to d-line, and θgF indicates partial dispersion ratio between g-line (wavelength 435.84 nm) and F-line (wavelength 486.13 nm).

  The (aperture) attached to the surface number indicates that the aperture stop S is located at that position. The radius of curvature with respect to the plane or the aperture stop S is indicated by ∞ (infinity).

  * (Asterisk) attached to the surface number indicates that the lens surface shape is aspheric.

[Aspherical surface data] shows the values of the respective coefficients that give the aspherical shape of the lens surface marked with * in [surface data]. The shape of the aspheric surface is represented by the following equation. In the following equation, y represents the displacement from the optical axis in a direction orthogonal to the optical axis, z represents the displacement (sag amount) from the intersection of the aspherical surface and the optical axis in the optical axis direction, and r represents the radius of curvature of the reference spherical surface. The conic coefficient is represented by K. In addition, the 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20th order aspherical coefficients are A3, A4, A5, When placed at A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, and A20, the coordinates of the aspheric surface are represented by the following equations.

  [Various data] shows values such as the zoom ratio and the focal length in each focal length state.

  [Variable interval data] shows the variable interval and the value of BF in each focal length state.

  [Lens group data] indicates the surface number of the most object side constituting each lens group and the combined focal length of the entire group.

  In the aberration diagrams corresponding to the examples, d, g, and C represent d-line, g-line, and C-line, respectively, and △ S and △ M represent a sagittal image plane and a meridional image plane, respectively. .

  In all of the following values, the focal length f, radius of curvature r, lens surface distance d, and other units of the length are expressed in millimeters (mm) unless otherwise specified. The system is not limited to this, because the same optical performance can be obtained in the proportional expansion and the proportional reduction.

FIG. 1 is a lens configuration diagram of a wide-angle lens system according to Embodiment 1 of the present invention.
The first embodiment is a variable power optical system and includes, in order from the object side, a first lens group G1 having a negative refractive power and a subsequent lens group GR having a positive refractive power as a whole. In order from the side, the second lens group G2 has a positive refractive power, the third lens group G3 has a positive refractive power, and the fourth lens group G4 has a positive refractive power. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture stop S moves together with the fourth lens group G4 during zooming.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, and a negative meniscus lens L3 having a convex surface facing the object side. The bi-concave lens L4 and a positive meniscus lens L5 having a convex surface facing the object side. The lens surface on the object side of the negative meniscus lens L1 and the lens surfaces on both sides of the negative meniscus lens L3 have a predetermined aspherical shape. Has become.

  The second lens group G2 includes, in order from the object side, a cemented lens composed of a negative meniscus lens L6 having a convex surface facing the object side and a positive meniscus lens L7 having a convex surface facing the object side. The entire second lens group G2 moves to the image plane side during focusing from an object distance at infinity to a short distance.

  The third lens group G3 includes a negative meniscus lens L8 having a convex surface facing the image side, and a cemented lens composed of a negative meniscus lens L9 having a convex surface facing the object side from the object side and a biconvex lens L10.

  The fourth lens group G4 includes a biconvex lens L11, a cemented lens including a negative meniscus lens L12 having a convex surface facing the object side and a biconvex lens L13, a biconcave lens L14, and a positive meniscus lens L15 having a convex surface facing the object side. It is composed of a cemented lens, a cemented lens composed of a negative meniscus lens L16 having a convex surface facing the object side and a positive meniscus lens L17 having a convex surface facing the object side, and a positive meniscus lens L18 having a convex surface facing the image side. The lens surfaces on both sides of the positive meniscus lens L18 have a predetermined aspherical shape.

  Further, in the wide-angle lens system according to the first embodiment, when zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 decreases, and the second lens group G2 and the third lens group After the distance to G3 increases, the distance decreases from the middle of the zoom range, and the distance between the third lens group G3 and the fourth lens group G4 decreases.

Next, specifications of the wide-angle lens system according to Example 1 will be described below.
Numerical example 1
Unit: mm
[Surface data]
Surface number rd nd vd θgF
1 * 85.4412 3.2000 1.69350 53.18 0.5482
2 25.6415 5.9311
3 32.2488 1.7000 1.59282 68.62 0.5440
4 20.4022 9.9424
5 * 44.7525 2.4089 1.59271 66.97 0.5366
6 * 18.6004 8.2083
7 -143.3662 1.0000 1.59282 68.62 0.5440
8 65.2835 0.2500
9 32.7185 3.5498 1.84666 23.78 0.6191
10 78.5742 (d10)
11 47.9876 0.7000 1.92119 23.96 0.6201
12 18.0927 4.5235 1.75211 25.05 0.6191
13 1000.0000 (d13)
14 -45.9274 0.8473 1.80809 22.76 0.6285
15 -130.5409 0.1500
16 43.8526 0.8157 1.94595 17.98 0.6544
17 24.6033 5.0424 1.75520 27.51 0.6102
18 -238.9569 (d18)
19 (aperture) ∞ 1.2400
20 26.7826 5.4475 1.43700 95.10 0.5335
21 -82.1805 0.1500
22 27.6053 0.8000 1.72047 34.71 0.5834
23 14.2195 7.7162 1.55032 75.50 0.5399
24 -302.0534 3.1611
25 -42.7697 0.8000 1.95375 32.32 0.5900
26 16.5944 5.1186 1.92286 20.88 0.6388
27 165.2911 0.1500
28 30.6058 0.8000 1.88300 40.80 0.5654
29 15.3700 7.4494 1.55032 75.50 0.5399
30 146.1642 1.4019
31 * -300.0000 2.0350 1.55352 71.72 0.5397
32 * -70.4549 (BF)
Image plane ∞

[Aspheric data]
1 surface 5 surfaces 6 surfaces
K 0.00000E + 00 0.00000E + 00 -3.64842E-02
A3 0.00000E + 00 -5.23111E-05 -3.48559E-05
A4 8.58209E-06 -1.26716E-05 -1.50563E-05
A5 0.00000E + 00 -1.13040E-05 -1.10043E-05
A6 -1.40764E-08 1.95245E-06 1.72222E-06
A7 0.00000E + 00 -9.38134E-08 -4.71099E-08
A8 3.05748E-11 -7.82976E-10 -3.15483E-09
A9 0.00000E + 00 1.22496E-10 -5.86163E-11
A10 -5.97803E-14 1.97968E-12 1.76453E-11
A11 0.00000E + 00 -1.33295E-14 -1.10783E-13
A12 9.08590E-17 -1.10265E-14 -5.28181E-15
A13 0.00000E + 00 5.32582E-17 -8.35047E-16
A14 -9.58737E-20 7.28532E-18 5.89441E-17
A15 0.00000E + 00 1.89244E-19 -9.54814E-18
A16 6.40051E-23 -1.81192E-20 3.21284E-19
A17 0.00000E + 00 1.13899E-21 6.43253E-21
A18 -2.39147E-26 -2.99255E-23 -4.91029E-23
A19 0.00000E + 00 1.48595E-25 1.37261E-24
A20 3.78519E-30 -3.31214E-27 -5.09803E-25

31 32
K 0.00000E + 00 0.00000E + 00
A3 0.00000E + 00 0.00000E + 00
A4 -2.45667E-05 5.66654E-06
A5 0.00000E + 00 0.00000E + 00
A6 -8.17092E-08 5.42201E-08
A7 0.00000E + 00 0.00000E + 00
A8 2.81370E-09 -2.06458E-09
A9 0.00000E + 00 0.00000E + 00
A10 -7.26008E-11 3.25090E-11
A11 0.00000E + 00 0.00000E + 00
A12 1.11778E-12 -2.56410E-13
A13 0.00000E + 00 0.00000E + 00
A14 -9.83681E-15 1.03356E-15
A15 0.00000E + 00 0.00000E + 00
A16 4.86452E-17 -1.78037E-18
A17 0.00000E + 00 0.00000E + 00
A18 -1.24975E-19 -8.07610E-22
A19 0.00000E + 00 0.00000E + 00
A20 1.29336E-22 5.22718E-24

[Various data]
Zoom ratio 1.60
Wide-angle Medium telephoto Focal length 14.50 17.97 23.15
F-number 2.93 2.93 2.93
Full angle of view 2ω 114.29 100.68 84.92
Image height Y 21.63 21.63 21.63
Total lens length 141.1415 136.8766 135.0097

[Variable interval data] Wide-angle Medium telephoto Shooting distance ∞ ∞ ∞
d10 17.4502 9.3308 3.1517
d13 8.4183 10.2009 9.5800
d18 9.1955 5.5627 2.6650
BF 21.5383 27.2429 35.0738

[Lens group data]
Group Starting surface Focal length
G1 1 -18.7938
G2 11 108.8254
G3 14 172.7111
G4 19 43.8312

FIG. 8 is a lens configuration diagram of a wide-angle lens system according to Embodiment 2 of the present invention.
Example 2 is a variable power optical system, and includes, in order from the object side, a first lens group G1 having a negative refractive power and a subsequent lens group GR having a positive refractive power as a whole. In order from the side, the second lens group G2 has a positive refractive power, the third lens group G3 has a positive refractive power, and the fourth lens group G4 has a positive refractive power. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture stop S moves together with the fourth lens group G4 during zooming.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, and a negative meniscus lens L3 having a convex surface facing the object side. It comprises a biconcave lens L4 and a biconvex lens L5, and the lens surface on the object side of the negative meniscus lens L1 and the lens surfaces on both sides of the negative meniscus lens L3 have a predetermined aspheric shape.

  The second lens group G2 includes, in order from the object side, a cemented lens composed of a negative meniscus lens L6 having a convex surface facing the object side and a positive meniscus lens L7 having a convex surface facing the object side. The entire second lens group G2 moves to the image plane side during focusing from an object distance at infinity to a short distance.

  The third lens group G3 includes a cemented lens including a biconvex lens L8 and a biconcave lens L9, and a positive meniscus lens L10 having a convex surface facing the object side. The lens surfaces on both sides of the positive meniscus lens L10 have a predetermined aspherical shape.

  The fourth lens group G4 includes, in order from the object side, a positive meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a positive meniscus lens L13 having a convex surface facing the object side. A lens, a cemented lens composed of a negative meniscus lens L14 having a convex surface facing the object side and a biconvex lens L15, a cemented lens composed of a biconcave lens L16 and a positive meniscus lens L17 having a convex surface facing the object side, and a biconvex lens L18 The lens surfaces on both sides of the biconvex lens L18 have a predetermined aspherical shape.

  In the wide-angle lens system according to the second embodiment, the distance between the first lens group G1 and the second lens group G2 decreases during zooming from the wide-angle end to the telephoto end, and the second lens group G2 and the third lens group After the distance to G3 increases, the distance decreases from the middle of the zoom range, and the distance between the third lens group G3 and the fourth lens group G4 decreases.

Next, specifications of the wide-angle lens system according to the second embodiment will be described below.
Numerical example 2
Unit: mm
[Surface data]
Surface number rd nd vd θgF
1 * 70.4362 3.2688 1.69350 53.18 0.5482
2 26.2053 8.2888
3 39.1118 1.8000 1.59282 68.62 0.5440
4 19.8260 9.3405
5 * 62.5655 1.8393 1.59201 67.02 0.5358
6 * 27.3920 9.0857
7 -49.8873 1.4000 1.59282 68.62 0.5440
8 73.2389 0.1500
9 41.4682 4.3226 1.85478 24.80 0.6122
10 226.1881 (d10)
11 43.5485 0.8000 1.92119 23.96 0.6201
12 17.2071 4.6530 1.75211 25.05 0.6191
13 1572.4443 (d13)
14 850.7053 5.1991 1.85478 24.80 0.6122
15 -17.8269 0.8000 1.80809 22.76 0.6285
16 75.4697 0.1500
17 * 26.4504 2.9733 1.55332 71.68 0.5402
18 * 62.8100 (d18)
19 (aperture) ∞ 1.1000
20 27.2056 4.0471 1.49700 81.61 0.5388
21 1052.3509 0.1500
22 23.0464 1.0000 1.80610 40.73 0.5671
23 13.4116 6.9022 1.55032 75.50 0.5399
24 923.5859 0.1500
25 25.8717 0.8000 1.74330 49.22 0.5493
26 11.3804 5.4303 1.49700 81.61 0.5388
27 -473.9094 0.8562
28 -83.2691 1.0000 1.88300 40.80 0.5654
29 13.8202 3.7227 1.80809 22.76 0.6285
30 33.2018 1.8312
31 * 59.5236 2.8742 1.55332 71.68 0.5402
32 * -101.3259 (BF)
Image plane ∞

[Aspheric data]
1 surface 5 surfaces 6 surfaces
K 0.00000E + 00 0.00000E + 00 0.00000E + 00
A3 0.00000E + 00 0.00000E + 00 0.00000E + 00
A4 6.57085E-06 -4.14215E-05 -3.28976E-05
A5 0.00000E + 00 0.00000E + 00 0.00000E + 00
A6 -5.54117E-09 5.33347E-07 5.75999E-07
A7 0.00000E + 00 0.00000E + 00 0.00000E + 00
A8 5.99382E-12 -2.84879E-09 -2.93649E-09
A9 0.00000E + 00 0.00000E + 00 0.00000E + 00
A10 -3.00326E-15 9.07865E-12 8.04066E-12
A11 0.00000E + 00 0.00000E + 00 0.00000E + 00
A12 7.00625E-19 -1.53961E-14 -5.06370E-15
A13 0.00000E + 00 0.00000E + 00 0.00000E + 00
A14 0.00000E + 00 1.08358E-17 -1.08598E-17
A15 0.00000E + 00 0.00000E + 00 0.00000E + 00
A16 0.00000E + 00 0.00000E + 00 0.00000E + 00
A17 0.00000E + 00 0.00000E + 00 0.00000E + 00
A18 0.00000E + 00 0.00000E + 00 0.00000E + 00
A19 0.00000E + 00 0.00000E + 00 0.00000E + 00
A20 0.00000E + 00 0.00000E + 00 0.00000E + 00

17 18
K 0.00000E + 00 0.00000E + 00
A3 0.00000E + 00 0.00000E + 00
A4 -1.41090E-05 -6.52464E-06
A5 0.00000E + 00 0.00000E + 00
A6 3.80536E-08 3.87744E-08
A7 0.00000E + 00 0.00000E + 00
A8 -6.02419E-10 -6.26071E-10
A9 0.00000E + 00 0.00000E + 00
A10 3.15197E-12 3.28488E-12
A11 0.00000E + 00 0.00000E + 00
A12 0.00000E + 00 0.00000E + 00
A13 0.00000E + 00 0.00000E + 00
A14 0.00000E + 00 0.00000E + 00
A15 0.00000E + 00 0.00000E + 00
A16 0.00000E + 00 0.00000E + 00
A17 0.00000E + 00 0.00000E + 00
A18 0.00000E + 00 0.00000E + 00
A19 0.00000E + 00 0.00000E + 00
A20 0.00000E + 00 0.00000E + 00

31 32
K 0.00000E + 00 0.00000E + 00
A3 0.00000E + 00 0.00000E + 00
A4 -1.78738E-05 1.45712E-05
A5 0.00000E + 00 0.00000E + 00
A6 -3.83809E-08 -7.77842E-08
A7 0.00000E + 00 0.00000E + 00
A8 -1.35717E-09 -9.39808E-10
A9 0.00000E + 00 0.00000E + 00
A10 1.51933E-11 7.23165E-12
A11 0.00000E + 00 0.00000E + 00
A12 0.00000E + 00 0.00000E + 00
A13 0.00000E + 00 0.00000E + 00
A14 0.00000E + 00 0.00000E + 00
A15 0.00000E + 00 0.00000E + 00
A16 0.00000E + 00 0.00000E + 00
A17 0.00000E + 00 0.00000E + 00
A18 0.00000E + 00 0.00000E + 00
A19 0.00000E + 00 0.00000E + 00
A20 0.00000E + 00 0.00000E + 00

[Various data]
Zoom ratio 1.60
Wide-angle Medium telephoto Focal length 14.50 17.80 23.15
F-number 2.93 2.93 2.93
Full angle of view 2ω 114.20 101.12 84.98
Image height Y 21.63 21.63 21.63
Total lens length 133.1000 129.8569 128.7234

[Variable interval data] Wide-angle Medium telephoto Shooting distance ∞ ∞ ∞
d10 13.6655 7.2040 1.6000
d13 4.9365 6.3901 6.2716
d18 9.1999 5.9263 2.9233
BF 21.3629 26.4014 33.9934

[Lens group data]
Group Starting surface Focal length
G1 1 -17.9139
G2 11 91.2908
G3 14 190.1798
G4 19 39.6370

FIG. 15 is a lens configuration diagram of a wide-angle lens system according to Embodiment 3 of the present invention.
Example 3 is a variable-power optical system, and includes, in order from the object side, a first lens group G1 having a negative refractive power and a subsequent lens group GR having a positive refractive power as a whole. In order from the side, the second lens group G2 has a negative refractive power, a third lens group G3 has a positive refractive power, a fourth lens group G4 has a positive refractive power, and a fifth lens group G5 has a positive refractive power. Is done. An aperture stop S is disposed between the fourth lens group G4 and the fifth lens group G5, and the aperture stop S moves together with the fifth lens group G5 during zooming.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, and a negative meniscus lens L3 having a convex surface facing the object side. The bi-concave lens L4 and a positive meniscus lens L5 having a convex surface facing the object side. The lens surface on the object side of the negative meniscus lens L1 and the lens surfaces on both sides of the negative meniscus lens L3 have a predetermined aspherical shape. Has become.

  The second lens group G2 includes a negative meniscus lens L6 having a convex surface facing the object side in order from the object side.

  The third lens group G3 includes, in order from the object side, a cemented lens composed of a negative meniscus lens L7 having a convex surface facing the object side and a positive meniscus lens L8 having a convex surface facing the object side. The entire third lens group G3 moves to the image plane side during focusing from an object distance at infinity to a short distance.

  The fourth lens group G4 includes a positive meniscus lens L9 having a convex surface facing the object side, and a cemented lens including a biconcave lens L10 and a biconvex lens L11. The lens surfaces on both sides of the positive meniscus lens L9 have a predetermined aspherical shape.

  The fifth lens group G5 includes, in order from the object side, a positive meniscus lens L12 having a convex surface facing the object side, a negative meniscus lens L13 having a convex surface facing the object side, and a positive meniscus lens L14 having a convex surface facing the object side. A cemented lens composed of a lens, a negative meniscus lens L15 having a convex surface facing the object side and a positive meniscus lens L16 having a convex surface facing the object side, and a cemented lens composed of a biconcave lens L17 and a positive meniscus lens L18 having a convex surface facing the object side It is composed of a lens and a biconvex lens L19, and the lens surfaces on both sides of the biconvex lens L19 have a predetermined aspherical shape.

  Further, in the wide-angle lens system according to the third embodiment, when zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 decreases, and the fourth lens group G4 and the fifth lens group The distance from G5 decreases. The distance between the second lens group G2 and the third lens group G3 and the distance between the third lens group G3 and the fourth lens group G4 do not change during zooming at infinity.

Next, specifications of the wide-angle lens system according to the third embodiment will be described below.
Numerical example 3
Unit: mm
[Surface data]
Surface number rd nd vd θgF
1 * 62.1270 3.1000 1.69350 53.18 0.5482
2 25.9720 9.4134
3 44.4365 1.7000 1.76385 48.49 0.5589
4 19.0805 9.8439
5 * 111.8526 1.7500 1.59201 67.02 0.5358
6 * 46.1646 7.1975
7 -56.0767 1.2000 1.43700 95.10 0.5335
8 50.6852 0.1500
9 36.5346 4.4755 1.85478 24.80 0.6122
10 122.1284 (d10)
11 50.9595 1.0000 1.72916 54.67 0.5452
12 40.8982 (d12)
13 29.8814 0.8000 1.95375 32.32 0.5900
14 15.1467 5.7973 1.69895 30.05 0.6028
15 1003.6255 (d15)
16 * 49.6536 2.8072 1.58313 59.46 0.5404
17 * 105.3701 1.5420
18 -62.5451 0.8000 1.85478 24.80 0.6122
19 22.9434 4.7872 1.91082 35.25 0.5821
20 -115.9850 (d20)
21 (aperture) ∞ 1.1000
22 27.0105 4.0101 1.55032 75.50 0.5399
23 681.5372 0.1500
24 21.5100 1.0000 1.77250 49.62 0.5503
25 13.2280 6.8392 1.49700 81.61 0.5388
26 806.0308 0.1500
27 25.3231 0.8000 1.77250 49.62 0.5503
28 11.4625 5.0838 1.49700 81.61 0.5388
29 105.9287 1.0274
30 -70.8196 1.0000 1.88300 40.80 0.5654
31 15.6075 3.4771 1.80809 22.76 0.6285
32 36.4186 0.6113
33 * 59.9235 3.1623 1.55332 71.68 0.5402
34 * -53.5427 (BF)
Image plane ∞

[Aspheric data]
1 surface 5 surfaces 6 surfaces
K 0.00000E + 00 0.00000E + 00 0.00000E + 00
A3 0.00000E + 00 0.00000E + 00 0.00000E + 00
A4 5.64304E-06 -4.04402E-06 3.02847E-06
A5 0.00000E + 00 0.00000E + 00 0.00000E + 00
A6 -3.31532E-09 8.28678E-08 8.10100E-08
A7 0.00000E + 00 0.00000E + 00 0.00000E + 00
A8 5.19167E-12 7.67359E-11 2.13471E-10
A9 0.00000E + 00 0.00000E + 00 0.00000E + 00
A10 -3.51415E-15 -1.43493E-12 -2.59811E-12
A11 0.00000E + 00 0.00000E + 00 0.00000E + 00
A12 1.44648E-18 4.76781E-15 9.87834E-15
A13 0.00000E + 00 0.00000E + 00 0.00000E + 00
A14 0.00000E + 00 -5.69577E-18 -1.62148E-17
A15 0.00000E + 00 0.00000E + 00 0.00000E + 00
A16 0.00000E + 00 0.00000E + 00 0.00000E + 00
A17 0.00000E + 00 0.00000E + 00 0.00000E + 00
A18 0.00000E + 00 0.00000E + 00 0.00000E + 00
A19 0.00000E + 00 0.00000E + 00 0.00000E + 00
A20 0.00000E + 00 0.00000E + 00 0.00000E + 00

16 17
K 0.00000E + 00 0.00000E + 00
A3 0.00000E + 00 0.00000E + 00
A4 -1.67168E-06 -3.12521E-06
A5 0.00000E + 00 0.00000E + 00
A6 1.08791E-07 1.01441E-07
A7 0.00000E + 00 0.00000E + 00
A8 -4.37216E-10 -5.18358E-10
A9 0.00000E + 00 0.00000E + 00
A10 4.01041E-12 4.35919E-12
A11 0.00000E + 00 0.00000E + 00
A12 0.00000E + 00 0.00000E + 00
A13 0.00000E + 00 0.00000E + 00
A14 0.00000E + 00 0.00000E + 00
A15 0.00000E + 00 0.00000E + 00
A16 0.00000E + 00 0.00000E + 00
A17 0.00000E + 00 0.00000E + 00
A18 0.00000E + 00 0.00000E + 00
A19 0.00000E + 00 0.00000E + 00
A20 0.00000E + 00 0.00000E + 00

33 surfaces 34 surfaces
K 0.00000E + 00 0.00000E + 00
A3 0.00000E + 00 0.00000E + 00
A4 -1.07408E-05 2.20811E-05
A5 0.00000E + 00 0.00000E + 00
A6 1.78637E-07 1.28295E-07
A7 0.00000E + 00 0.00000E + 00
A8 -1.31521E-09 -7.11408E-10
A9 0.00000E + 00 0.00000E + 00
A10 1.13478E-11 4.09428E-12
A11 0.00000E + 00 0.00000E + 00
A12 0.00000E + 00 0.00000E + 00
A13 0.00000E + 00 0.00000E + 00
A14 0.00000E + 00 0.00000E + 00
A15 0.00000E + 00 0.00000E + 00
A16 0.00000E + 00 0.00000E + 00
A17 0.00000E + 00 0.00000E + 00
A18 0.00000E + 00 0.00000E + 00
A19 0.00000E + 00 0.00000E + 00
A20 0.00000E + 00 0.00000E + 00

[Various data]
Zoom ratio 1.60
Wide-angle Medium telephoto Focal length 14.50 17.68 23.15
F-number 2.93 2.93 2.93
Full angle of view 2ω 114.18 101.48 84.98
Image height Y 21.63 21.63 21.63
Total lens length 134.3000 130.1723 128.1336

[Variable interval data] Wide-angle Medium telephoto Shooting distance ∞ ∞ ∞
d10 14.1533 7.7721 1.4000
d12 1.4000 1.4000 1.4000
d15 3.9103 3.9103 3.9103
d20 7.0127 4.6959 1.5028
BF 23.0484 27.6187 35.1453

[Lens group data]
Group Starting surface Focal length
G1 1 -19.1136
G2 11 -296.5171
G3 13 68.1908
G4 16 314.7230
G5 21 39.4864

FIG. 22 is a lens configuration diagram of a wide-angle lens system according to Example 4 of the present invention.
Example 4 is a variable power optical system, and includes, in order from the object side, a first lens group G1 having a negative refractive power and a subsequent lens group GR having a positive refractive power as a whole. In order from the side, the second lens group G2 has a positive refractive power, the third lens group G3 has a positive refractive power, and the fourth lens group G4 has a positive refractive power. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture stop S moves together with the fourth lens group G4 during zooming.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, and a negative meniscus lens L3 having a convex surface facing the object side. The bi-concave lens L4 and a positive meniscus lens L5 having a convex surface facing the object side. The lens surface on the object side of the negative meniscus lens L1 and the lens surfaces on both sides of the negative meniscus lens L3 have a predetermined aspherical shape. Has become.

  The second lens group G2 includes a biconvex lens L6. The entire second lens group G2 moves to the image plane side during focusing from an object distance at infinity to a short distance. The lens surfaces on both sides of the biconvex lens L6 have a predetermined aspherical shape.

  The third lens group G3 includes a cemented lens including a biconvex lens L7 and a biconcave lens L8, and a cemented lens including a negative meniscus lens L9 having a convex surface facing the object side and a positive meniscus lens L10 having a convex surface facing the object side. Have been.

  The fourth lens group G4 includes a cemented lens including a biconvex lens L11, a negative meniscus lens L12 having a convex surface facing the object side, and a positive meniscus lens L13 having a convex surface facing the object side, and a negative meniscus having a convex surface facing the object side. A cemented lens composed of a lens L14 and a biconvex lens L15, a cemented lens composed of a biconcave lens L16, a positive meniscus lens L17 having a convex surface facing the object side, and a biconvex lens L18, lenses on both sides of the biconvex lens L18 The surface has a predetermined aspherical shape.

  Further, in the wide-angle lens system according to the fourth embodiment, when zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 decreases, and the second lens group G2 and the third lens group The distance between G3 and G3 increases, and the distance between third lens group G3 and fourth lens group G4 decreases.

Next, specifications of the wide-angle lens system according to Example 4 will be described below.
Numerical example 4
Unit: mm
[Surface data]
Surface number rd nd vd θgF
1 * 68.1609 3.2000 1.69350 53.18 0.5482
2 26.3693 8.7670
3 41.2461 1.8000 1.59282 68.62 0.5440
4 19.7745 9.1547
5 * 60.8593 1.7500 1.59201 67.02 0.5358
6 * 28.0939 8.9436
7 -54.2371 1.4000 1.59282 68.62 0.5440
8 52.4509 0.3343
9 39.5811 4.6054 1.85478 24.80 0.6122
10 286.8626 (d10)
11 * 113.7450 2.2826 1.83441 37.28 0.5772
12 * -250.2800 (d12)
13 1169.8598 4.3764 1.73800 32.33 0.5899
14 -22.0158 0.8000 1.72825 28.32 0.6058
15 101.9596 0.1932
16 23.6757 1.0000 1.95375 32.32 0.5900
17 17.3832 5.0764 1.54072 47.20 0.5677
18 127.1087 (d18)
19 (aperture) ∞ 1.1000
20 31.2673 3.9143 1.49700 81.61 0.5388
21 -399.2320 0.1500
22 23.0238 1.0000 1.80610 40.73 0.5671
23 13.5278 6.7879 1.55032 75.50 0.5399
24 546.4487 0.1500
25 25.9787 1.4522 1.80610 40.73 0.5671
26 12.2358 4.7661 1.49700 81.61 0.5388
27 -272.7786 0.8256
28 -71.7333 1.0000 1.88300 40.80 0.5654
29 13.7504 3.5658 1.80809 22.76 0.6285
30 36.1983 2.3633
31 * 75.0131 2.8773 1.55332 71.68 0.5402
32 * -97.5471 (BF)
Image plane ∞

[Aspheric data]
1 surface 5 surfaces 6 surfaces
K 0.00000E + 00 0.00000E + 00 0.00000E + 00
A3 0.00000E + 00 0.00000E + 00 0.00000E + 00
A4 6.24818E-06 -4.34192E-05 -3.61640E-05
A5 0.00000E + 00 0.00000E + 00 0.00000E + 00
A6 -4.72366E-09 5.22866E-07 5.64120E-07
A7 0.00000E + 00 0.00000E + 00 0.00000E + 00
A8 5.00383E-12 -2.42012E-09 -2.40002E-09
A9 0.00000E + 00 0.00000E + 00 0.00000E + 00
A10 -2.76706E-15 6.67134E-12 5.39575E-12
A11 0.00000E + 00 0.00000E + 00 0.00000E + 00
A12 8.25703E-19 -1.00186E-14 -2.70738E-15
A13 0.00000E + 00 0.00000E + 00 0.00000E + 00
A14 0.00000E + 00 6.32660E-18 -7.39494E-18
A15 0.00000E + 00 0.00000E + 00 0.00000E + 00
A16 0.00000E + 00 0.00000E + 00 0.00000E + 00
A17 0.00000E + 00 0.00000E + 00 0.00000E + 00
A18 0.00000E + 00 0.00000E + 00 0.00000E + 00
A19 0.00000E + 00 0.00000E + 00 0.00000E + 00
A20 0.00000E + 00 0.00000E + 00 0.00000E + 00

11 12
K 0.00000E + 00 0.00000E + 00
A3 0.00000E + 00 0.00000E + 00
A4 -1.96794E-06 2.35238E-06
A5 0.00000E + 00 0.00000E + 00
A6 6.32479E-08 5.74545E-08
A7 0.00000E + 00 0.00000E + 00
A8 -3.73385E-10 -3.58586E-10
A9 0.00000E + 00 0.00000E + 00
A10 1.74175E-12 1.80734E-12
A11 0.00000E + 00 0.00000E + 00
A12 0.00000E + 00 0.00000E + 00
A13 0.00000E + 00 0.00000E + 00
A14 0.00000E + 00 0.00000E + 00
A15 0.00000E + 00 0.00000E + 00
A16 0.00000E + 00 0.00000E + 00
A17 0.00000E + 00 0.00000E + 00
A18 0.00000E + 00 0.00000E + 00
A19 0.00000E + 00 0.00000E + 00
A20 0.00000E + 00 0.00000E + 00

31 32
K 0.00000E + 00 0.00000E + 00
A3 0.00000E + 00 0.00000E + 00
A4 -1.14839E-05 1.74860E-05
A5 0.00000E + 00 0.00000E + 00
A6 -8.46161E-08 -7.77265E-08
A7 0.00000E + 00 0.00000E + 00
A8 6.71571E-11 -2.46545E-10
A9 0.00000E + 00 0.00000E + 00
A10 6.99295E-12 4.55658E-12
A11 0.00000E + 00 0.00000E + 00
A12 0.00000E + 00 0.00000E + 00
A13 0.00000E + 00 0.00000E + 00
A14 0.00000E + 00 0.00000E + 00
A15 0.00000E + 00 0.00000E + 00
A16 0.00000E + 00 0.00000E + 00
A17 0.00000E + 00 0.00000E + 00
A18 0.00000E + 00 0.00000E + 00
A19 0.00000E + 00 0.00000E + 00
A20 0.00000E + 00 0.00000E + 00

[Various data]
Zoom ratio 1.60
Wide-angle Medium telephoto Focal length 14.50 17.86 23.15
F-number 2.93 2.93 2.93
Full angle of view 2ω 114.20 100.94 84.98
Image height Y 21.63 21.63 21.63
Total lens length 133.1001 130.1846 129.3658

[Variable interval data] Wide-angle Medium telephoto Shooting distance ∞ ∞ ∞
d10 15.2620 7.8806 1.7869
d12 4.0754 7.2913 8.0379
d18 9.8407 5.6870 2.4689
BF 20.2857 25.6895 33.4358

[Lens group data]
Group Starting surface Focal length
G1 1 -17.9347
G2 11 93.9914
G3 14 146.0606
G4 19 42.9206

FIG. 29 is a lens configuration diagram of a wide-angle lens system according to Example 5 of the present invention.
Example 5 is a variable power optical system, which includes, in order from the object side, a first lens group G1 having a negative refractive power and a subsequent lens group GR having a positive refractive power as a whole. In order from the side, the second lens group G2 has a positive refractive power, the third lens group G3 has a positive refractive power, and the fourth lens group G4 has a positive refractive power. An aperture S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture stop S moves integrally with the fourth lens group G4 during zooming.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the object side, and a negative meniscus lens L3 having a convex surface facing the object side. The bi-concave lens L4 and a positive meniscus lens L5 having a convex surface facing the object side. The lens surface on the object side of the negative meniscus lens L1 and the lens surfaces on both sides of the negative meniscus lens L3 have a predetermined aspherical shape. Has become.

  The second lens group G2 includes, in order from the object side, a cemented lens composed of a negative meniscus lens L6 having a convex surface facing the object side and a positive meniscus lens L7 having a convex surface facing the object side. The entire second lens group G2 moves to the image plane side during focusing from an object distance at infinity to a short distance.

  The third lens group G3 includes a negative meniscus lens L8 having a convex surface facing the image side, and a cemented lens composed of a negative meniscus lens L9 having a convex surface facing the object side from the object side and a biconvex lens L10.

  The fourth lens group G4 includes a biconvex lens L11, a cemented lens including a negative meniscus lens L12 having a convex surface facing the object side and a biconvex lens L13, a biconcave lens L14, and a positive meniscus lens L15 having a convex surface facing the object side. It is composed of a cemented lens, a cemented lens composed of a negative meniscus lens L16 having a convex surface facing the object side and a positive meniscus lens L17 having a convex surface facing the object side, and a positive meniscus lens L18 having a convex surface facing the image side. The lens surfaces on both sides of the positive meniscus lens L18 have a predetermined aspherical shape.

  In the wide-angle lens system according to the fifth embodiment, at the time of zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 decreases, and the second lens group G2 and the third lens group After the distance to G3 increases, the distance decreases from the middle of the zoom range, and the distance between the third lens group G3 and the fourth lens group G4 decreases.

Next, specifications of the wide-angle lens system according to Example 5 are shown below.
Numerical example 5
Unit: mm
[Surface data]
Surface number rd nd vd θgF
1 * 83.0880 3.3719 1.69350 53.18 0.5482
2 25.6526 5.5230
3 31.2009 1.7500 1.72916 54.67 0.5452
4 20.6650 9.5469
5 * 40.6428 2.3978 1.59271 66.97 0.5366
6 * 19.1190 8.5711
7 -110.2901 1.0000 1.55032 75.50 0.5399
8 56.1679 0.2500
9 32.9544 3.6521 1.84666 23.78 0.6191
10 81.1775 (d10)
11 50.5714 0.7000 1.92119 23.96 0.6201
12 18.5534 4.5755 1.75211 25.05 0.6191
13 -2000.0000 (d13)
14 -48.7924 0.9000 1.80809 22.76 0.6285
15 -122.4980 0.1500
16 48.9240 0.9000 1.94595 17.98 0.6544
17 26.8957 4.8266 1.75520 27.53 0.6090
18 -474.9724 (d18)
19 (aperture) ∞ 1.2400
20 29.2085 5.5251 1.43700 95.10 0.5335
21 -78.1829 0.1500
22 27.1604 0.8000 1.73800 32.33 0.5899
23 15.3905 7.9110 1.55032 75.50 0.5399
24 -212.2955 3.5460
25 -49.8392 0.8000 1.95375 32.32 0.5900
26 16.6892 5.1258 1.92286 20.88 0.6388
27 130.1255 0.1500
28 30.2863 0.8000 1.88300 40.80 0.5654
29 15.1782 7.4175 1.55032 75.50 0.5399
30 112.0728 1.5198
31 * -300.0000 2.0350 1.55352 71.72 0.5397
32 * -70.4549 (BF)
Image plane ∞

[Aspheric data]
1 surface 5 surfaces 6 surfaces
K 0.00000E + 00 0.00000E + 00 -3.24723E-02
A3 0.00000E + 00 -3.27633E-05 -1.32710E-05
A4 8.58209E-06 -1.65467E-05 -1.86768E-05
A5 0.00000E + 00 -1.13566E-05 -1.09416E-05
A6 -1.40764E-08 1.95894E-06 1.72558E-06
A7 0.00000E + 00 -9.35586E-08 -4.70165E-08
A8 3.05748E-11 -7.83065E-10 -3.16219E-09
A9 0.00000E + 00 1.22268E-10 -5.80649E-11
A10 -5.97803E-14 1.97110E-12 1.77084E-11
A11 0.00000E + 00 -1.35540E-14 -1.04568E-13
A12 9.08590E-17 -1.10171E-14 -5.02411E-15
A13 0.00000E + 00 5.37605E-17 -8.36470E-16
A14 -9.58737E-20 7.32019E-18 5.87290E-17
A15 0.00000E + 00 1.90359E-19 -9.58595E-18
A16 6.40051E-23 -1.81802E-20 3.20485E-19
A17 0.00000E + 00 1.13132E-21 6.29329E-21
A18 -2.39147E-26 -3.05309E-23 -7.02168E-23
A19 0.00000E + 00 1.55414E-25 2.13517E-24
A20 3.78519E-30 -2.09772E-27 -4.55954E-25


31 32
K 0.00000E + 00 0.00000E + 00
A3 0.00000E + 00 0.00000E + 00
A4 -2.24020E-05 5.66654E-06
A5 0.00000E + 00 0.00000E + 00
A6 -9.63667E-08 5.42201E-08
A7 0.00000E + 00 0.00000E + 00
A8 2.26911E-09 -2.06458E-09
A9 0.00000E + 00 0.00000E + 00
A10 -5.23509E-11 3.25090E-11
A11 0.00000E + 00 0.00000E + 00
A12 8.17734E-13 -2.56410E-13
A13 0.00000E + 00 0.00000E + 00
A14 -7.45184E-15 1.03356E-15
A15 0.00000E + 00 0.00000E + 00
A16 3.80064E-17 -1.78037E-18
A17 0.00000E + 00 0.00000E + 00
A18 -9.98826E-20 -8.07610E-22
A19 0.00000E + 00 0.00000E + 00
A20 1.04979E-22 5.22718E-24

[Various data]
Zoom ratio 1.66
Wide-angle Medium telephoto Focal length 14.50 18.15 24.13
F-number 2.93 2.93 2.93
Full angle of view 2ω 114.73 100.21 82.48
Image height Y 21.63 21.63 21.63
Total lens length 143.0000 138.2931 136.2793

[Variable interval data] Wide-angle Medium telephoto Shooting distance ∞ ∞ ∞
d10 17.6144 9.5336 3.1464
d13 8.4838 10.2488 9.5124
d18 10.0833 5.7837 2.0272
BF 21.6834 27.5919 36.4581

[Lens group data]
Group Starting surface Focal length
G1 1 -18.7991
G2 11 104.9589
G3 14 245.6701
G4 19 41.5731

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

The values corresponding to the conditional expressions corresponding to the above embodiments are shown below.
Conditional expression / Example EX1 EX2 EX3 EX4 EX5
(1) DPS / HIM 0.43 0.43 0.32 0.45 0.47
(2) MRW ＾ 2 × (1-MFW ＾ 2) -0.45 -0.52 -0.73 -0.53 -0.46
(3) √ (fw × ft) / fF 0.17 0.20 0.27 0.19 0.18
(4) √ (fw × ft) / fP 0.11 0.10 0.06 0.13 0.08

S: aperture stop I: image plane G1: first lens group G2: second lens group G3: third lens group G4: fourth lens group G5: fifth lens group GR: subsequent lens group GF: focusing lens group GP : C-line (wavelength λ = 656.3 nm)
dd line (wavelength λ = 587.6 nm)
g g line (wavelength λ = 435.8 nm)
Y Image height ΔS Sagittal image plane ΔM Medial image plane

Claims (6)

In order from the object side, the first lens group G1 having a negative refractive power and the subsequent lens group GR having a positive refractive power as a whole are configured.
The subsequent lens group GR has an aperture stop S, an aperture front lens group GP on the object side, and a focusing lens group GF that moves to focus on the object side.
The front lens group GP and the focusing lens group GF have a positive refractive power, and at the time of zooming from the wide-angle end to the telephoto end, at least the air gap between the first lens group G1 and the subsequent lens group GR is reduced. A wide-angle lens system which decreases and satisfies the following conditional expression.
(1) 0.28 <DPS / HIM <1.00
However,
DPS: distance on the optical axis from the most image side surface of the front lens group GP of the diaphragm to the aperture stop S at the time of focusing on an object at infinity at the wide angle end HIM: maximum image height at the time of focusing on an object at infinity at the wide angle end The wide-angle lens system according to claim 1, wherein the following conditional expression is satisfied.
(2) −1.00 <MRW ＾ 2 × (1−MFW ＾ 2) <− 0.30
However,
MFW: lateral magnification of the focusing lens group GF when focusing on an object at infinity at the wide-angle end MRW: composite lateral magnification from the front lens group GP on the focusing side to an optical surface closest to the image side when focusing on an object at infinity at the wide-angle end The wide-angle lens system according to claim 1, wherein the following conditional expression is satisfied.
(3) 0.10 <√ (fw × ft) / fF <0.50
(4) 0.04 <√ (fw × ft) / fP <0.20
However,
fw: focal length ft of the entire lens system at infinity shooting at the wide-angle end ft: focal length fF of the entire lens system at infinity shooting at the telephoto end fF: focal length fP of the focusing lens group GF: the front lens group of the diaphragm GP focal length   The said 1st lens group G1 has four or more lenses which have negative refracting power, Three or more of them are meniscus lenses with the convex surface turned to the object side, Claims 1 thru | or 2 characterized by the above-mentioned. Item 4. A wide-angle lens system according to any one of Items 3.   The subsequent lens group GR is characterized in that the cemented surface has a convex surface facing the object side, and has at least four cemented lenses such that the refractive index of the medium on the object side is higher than the refractive index of the medium on the image side. The wide-angle lens system according to any one of claims 1 to 4, wherein   The wide-angle lens system according to any one of claims 1 to 5, wherein a lens closest to the image plane of the subsequent lens group GR has an aspheric surface.

Images