JP7160326B2 - Wide-angle lens system - Google Patents

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 or a video camera, adopting an inner focus system suitable for an autofocus camera, and vibrating the focus lens group slightly in the direction along the optical axis. The present invention relates to a wide-angle lens system that corrects changes in various aberrations such as astigmatism and chromatic aberration of magnification due to changes in focus position while suppressing the rate of change in image height when the lens is shifted.

2. Description of the Related Art In recent years, with the increase in the number of pixels of digital cameras and the like, strict correction of various aberrations in the optical system used has been required.

In addition, like the autofocus of mirrorless single-lens cameras that have become popular in recent years, the focus drive direction is constantly determined by continuing to vibrate the focus lens group in the direction along the optical axis (hereinafter referred to as wobbling). A type of inner focus method has been developed. At that time, if the rate of change in image height during wobbling is large, the viewer will perceive the change in magnification of the subject displayed on the screen, which will be an eyesore. Therefore, there is a demand for a focus type in which the image height change rate is small with respect to the focus change.

However, in conventionally proposed optical systems that suppress the rate of change in image height during wobbling, variations in various aberrations such as astigmatism and chromatic aberration due to changes in the focal position are large, resulting in It was difficult to maintain good imaging performance up to the time of distance focusing.

Examples of patent documents relating to the above are disclosed in Patent Document 1 and Patent Document 2.

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

Japanese Patent Application Laid-Open No. 2002-101001 proposes a variable magnification optical system that has a wide angle of view and suppresses the rate of change in image height when the focus lens group is wobbling. However, in the variable power optical system in Patent Document 1, spherical aberration and axial chromatic aberration vary greatly due to changes in the focal position. is difficult.

Japanese Patent Application Laid-Open No. 2002-100000 proposes a variable-magnification optical system that has a wide angle of view and suppresses fluctuations in aberration due to changes in the focal position. However, the variable power optical system in Patent Document 2 has a large image height fluctuation when the focus lens group is wobbling.

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

A first invention, which is a means for solving the above problems, comprises, 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 rear lens group GR has an aperture stop S, a front lens group GP on the object side of the aperture stop, and a focusing lens group GF on the object side of the lens group that moves when focusing. The focal lens group GF has a positive refractive power, and when zooming from the wide-angle end to the telephoto end, the air gap between at least the first lens group G1 and the subsequent lens group GR decreases, and the following conditional expression (1 )′, (2) and (4)′ are satisfied.
(1)'0.32≤DPS/HIM<1.00
(2) -1.00<MRW^2*(1-MFW^2)<-0.30
(4)'0.096≤√(fw×ft)/fP<0.15
however,
DPS: Distance on the optical axis from the most image-side surface of the lens group GP on the front side of the stop to the aperture stop S when focusing on an infinite object at the wide-angle end HIM: Maximum image height when focusing on an infinite object at the wide-angle end 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 fw from the lens group GP on the front side of the stop to the optical surface closest to the image side when focusing on an object at infinity at the wide-angle end : Focal length of the entire lens system when shooting at infinity at the wide-angle end ft: Focal length of the entire lens system when shooting at infinity at the telephoto end fP: Focal length of the lens group GP on the front side of the aperture

The second invention comprises, in order from the object side, a first lens group G1 having negative refractive power and a subsequent lens group GR having positive refractive power as a whole. The subsequent lens group GR has an aperture stop. S, an aperture front side lens group GP on the object side thereof, and a focusing lens group GF which moves when focusing on the object side thereof, wherein the aperture front side lens group GP and the focusing lens group GF have positive refraction. At the time of zooming from the wide-angle end to the telephoto end, the air gap between at least the first lens group G1 and the subsequent lens group GR is reduced, and the cemented surface of the subsequent lens group GR is a convex surface facing the object side. and has four or more sets of cemented lenses in which the refractive index of the medium on the object side is higher than the refractive index of the medium on the image plane side, and satisfies the following conditional expressions (1) and (4): It is a wide-angle lens system characterized by
(1) 0.28<DPS/HIM<1.00
(4) 0.04<√(fw×ft)/fP<0.20
however,
DPS: Distance on the optical axis from the most image-side surface of the lens group GP on the front side of the stop to the aperture stop S when focusing on an infinite object at the wide-angle end HIM: Maximum image height when focusing on an infinite object at the wide-angle end fw: focal length of the entire lens system when shooting at infinity at the wide-angle end ft: focal length of the entire lens system when shooting at infinity at the telephoto end fP: focal length of the lens group GP on the front side of the aperture

A third invention comprises, in order from the object side, a first lens group G1 having negative refractive power and a subsequent lens group GR having positive refractive power as a whole, wherein the subsequent lens group GR has an aperture stop. S, an aperture front side lens group GP on its object side, and a focusing lens group GF that moves when focusing on its object side, said aperture front side lens group GP and said focusing lens group GF having positive refraction. When zooming from the wide-angle end to the telephoto end, the air gap between at least the first lens group G1 and the subsequent lens group GR decreases, and the total angle of view 2ω at the wide-angle end is 114.20° or more. and the succeeding lens group GR has four or more sets of cemented lenses whose cemented surfaces are convex toward the object side and whose refractive index of the medium on the object side is higher than the refractive index of the medium on the image plane side. , and a wide-angle lens system that satisfies the following conditional expressions (1) and (2).
(1) 0.28<DPS/HIM<1.00
(2) -1.00<MRW^2*(1-MFW^2)<-0.30
however,
DPS: Distance on the optical axis from the most image-side surface of the lens group GP on the front side of the stop to the aperture stop S when focusing on an infinite object at the wide-angle end HIM: Maximum image height when focusing on an infinite object at the wide-angle end 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 lens group GP on the front side of the stop to the optical surface closest to the image side when focusing on an object at infinity at the wide-angle end

A fourth invention is the wide-angle lens system according to the second invention, characterized by 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 lens group GP on the front side of the stop to the optical surface closest to the image side when focusing on an object at infinity at the wide-angle end

A fifth invention is a wide-angle lens system according to the first invention or the second invention , characterized by further satisfying the following conditional expression (3) .
(3) 0.10<√(fw×ft)/fF<0.50
however,
fw: Focal length of the entire lens system when shooting at infinity at the wide-angle end
ft: Focal length of the entire lens system when shooting at infinity at the telephoto end
fF: focal length of the focusing lens group GF
fP: focal length of the lens group GP on the front side of the aperture

A sixth invention is a wide-angle lens system according to the third invention, characterized in that the following conditional expressions (3) and (4) are further satisfied.
(3) 0.10<√(fw×ft)/fF<0.50
(4) 0.04<√(fw×ft)/fP<0.20
however,
fw: focal length of the entire lens system when shooting at infinity at the wide-angle end ft: focal length of the entire lens system when shooting at infinity at the telephoto end fF: focal length of the focusing lens group GF fP: the lens group on the front side of the aperture GP focal length

In a seventh invention, in any one of the first to sixth inventions, the first lens group G1 further has four or more lenses having negative refractive power, and three or more of them are on the object side. It is a wide-angle lens system characterized by a meniscus lens with a convex surface facing upwards.

In an eighth invention, in any one of the first , fifth, and seventh inventions, the cemented surface of the subsequent lens group GR has a convex surface facing the object side, and a refractive index of a medium on the object side. The wide-angle lens system is characterized by having four or more pairs of cemented lenses having a refractive index higher than that of a medium on the image plane side.

A ninth invention is a wide-angle lens system according to any one of the first to eighth inventions, characterized in that the lens closest to the image plane side of the subsequent lens group GR has an aspherical surface. .

According to the present invention, by appropriately arranging the focus group, it is possible to provide a wide-angle lens system in which both image height fluctuations during wobbling and aberration fluctuations due to changes in the focusing position are suppressed.

FIG. 2 is a lens configuration diagram at infinity at the wide-angle end of the variable-magnification optical system of Example 1; Longitudinal aberration diagram at infinity at the wide-angle end of the variable power optical system of Example 1 Longitudinal aberration diagram at infinity at intermediate focal length of the variable power optical system of Example 1 Longitudinal aberration diagram at infinity at the telephoto end of the variable power optical system of Example 1 Lateral Aberration Diagram at Infinity at the Wide-Angle End of the Variable Magnification Optical System of Example 1 Lateral Aberration Diagram at Infinity at Intermediate Focal Length of the Variable Magnification Optical System of Example 1 Lateral Aberration Diagram at Infinity at the Telephoto End of the Variable Power Optical System of Example 1 FIG. 10 is a lens configuration diagram at infinity at the wide-angle end of the variable-magnification optical system of Example 2; Longitudinal aberration diagram at infinity at the wide-angle end of the variable magnification optical system of Example 2 Longitudinal aberration diagram at infinity at an intermediate focal length of the variable magnification optical system of Example 2 Longitudinal aberration diagram at infinity at the telephoto end of the variable magnification optical system of Example 2 Lateral Aberration Diagram at Infinity at the Wide-Angle End of the Variable Magnification Optical System of Example 2 Lateral Aberration Diagram at Infinity at Intermediate Focal Length of the Variable Power Optical System of Example 2 Lateral Aberration Diagram at Infinity at the Telephoto End of the Variable Magnification Optical System of Example 2 Lens configuration diagram at infinity at the wide-angle end of the variable-magnification optical system of Reference Example 3 Longitudinal aberration diagram at infinity at the wide-angle end of the variable-magnification optical system of Reference Example 3 Longitudinal aberration diagram at infinity of the intermediate focal length of the variable magnification optical system of Reference Example 3 Longitudinal aberration diagram at infinity at the telephoto end of the variable magnification optical system of Reference Example 3 Lateral aberration diagram at infinity at the wide-angle end of the variable magnification optical system of Reference Example 3 Lateral Aberration Diagram at Infinity at Intermediate Focal Length of the Variable Magnification Optical System of Reference Example 3 Lateral aberration diagram at infinity at the telephoto end of the variable magnification optical system of Reference Example 3 FIG. 10 is a lens configuration diagram at infinity at the wide-angle end of the variable-magnification optical system of Example 4; Longitudinal aberration diagram at infinity at the wide-angle end of the variable power optical system of Example 4 Longitudinal aberration diagram at infinity at an intermediate focal length of the variable power optical system of Example 4 Longitudinal aberration diagram at infinity at the telephoto end of the variable power optical system of Example 4 Lateral Aberration Diagram at Infinity at the Wide-Angle End of the Variable Magnification Optical System of Example 4 Lateral Aberration Diagram at Infinity at Intermediate Focal Length of the Variable Power Optical System of Example 4 Lateral Aberration Diagram at Infinity at the Telephoto End of the Variable Power Optical System of Example 4 Lens configuration diagram at infinity at the wide-angle end of the variable magnification optical system of Reference Example 5 Longitudinal aberration diagram at infinity at the wide-angle end of the variable-magnification optical system of Reference Example 5 Longitudinal aberration diagram at infinity at an intermediate focal length of the variable magnification optical system of Reference Example 5 Longitudinal aberration diagram at infinity at the telephoto end of the variable magnification optical system of Reference Example 5 Lateral aberration diagram at infinity at the wide-angle end of the variable magnification optical system of Reference Example 5 Lateral Aberration Diagram at Infinity at Intermediate Focal Length of the Variable Power Optical System of Reference Example 5 Lateral aberration diagram at infinity at the telephoto end of the variable magnification optical system of Reference Example 5

Examples of the optical system according to the present invention will be described in detail below. It should be noted that the following description of the 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 invention.

As can be seen from the lens configuration diagrams shown in FIGS. 1, 8, 15, 22, and 29, the wide-angle lens system of the present invention comprises, in order from the object side, the first lens group G1 having negative refractive power and the overall The rear lens group GR includes an aperture stop S, a front lens group GP on the object side of the aperture stop S, and a focusing lens group GP on the object side of the aperture stop S. The front lens group GP and the focusing lens group GF have positive refracting power, and when zooming from the wide-angle end to the telephoto end, at least the first lens group G1 and the rear lens group GF are combined. The structure is such that 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 image height fluctuations during wobbling and aberration fluctuations due to changes in the focus position are suppressed. Appropriate correction of changes in aberration coefficients is important.

By forming the image of the aperture stop S as seen from the focusing lens group GF at a distance, it is possible to minimize image height fluctuation during wobbling. In order to form an image of the aperture diaphragm S seen from the focusing lens group GF at a distance, the distance between the focusing lens group GF and the aperture diaphragm S may be widened, or the positive lens of the focusing lens group GF may be set. It is advantageous to increase the refractive power, but in any case, the aberration generated in the focusing lens group GF is worsened, and the fluctuation of the aberration due to the change of the focusing position becomes large.

Therefore, by arranging 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 While suppressing the positive refractive power of the GF, it is possible to form an image of the aperture stop S seen from the focusing lens group GF at a distance.

Here, by forming and projecting the image of the aperture stop S seen from the focusing lens group GF to a distant place, and by defining the lateral magnification of the focusing lens group GF and the combined lateral magnification of the subsequent lens groups, The reason why the image height fluctuation during wobbling can be minimized is as follows.

Image height variation due to wobbling can be represented by distortion aberration variation due to wobbling. According to Yoshiya Matsui, Lens Design Method, Kyoritsu Shuppan P88, the third-order distortion aberration coefficient V is expressed by the following reference formula (1).
V = J IV
This is expanded into the following, 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/(HQ))H^2Δ(1/(n s))+P(H'Q')/( H.Q.)

Therefore, in order to reduce the fluctuation of distortion due to wobbling, the fluctuation of the paraxial principal ray height of the focusing lens group due to wobbling should be reduced. Here, the position of the image of the aperture diaphragm by the lens group GP on the front side of the diaphragm, the lateral magnification of the focusing lens group GF, and the focusing lens with reference to the object side surface of the focusing lens group GF when the object distance is infinity. Fluctuation Δh of the principal ray height of the focusing lens group due to wobbling from the combined lateral magnification from the front lens group GP, which is a lens group behind the group, to the optical surface closest to the image side, and the height of the principal ray 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 of the aperture by the synthetic optical system of the surface from the focusing lens group GF at the wide-angle end to the front of the aperture when the object distance is infinite. Principal ray height h′ in the focusing lens group: Principal ray height in the focusing lens group during wobbling MF: Lateral magnification of the focusing lens group GF when focusing on an object at infinity MR: Aperture when focusing on an object at infinity Combined lateral magnification from the front lens group GP to the optical surface closest to the image side

Furthermore, the wide-angle lens system of the present invention is characterized by 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 lens group GP on the front side of the stop to the aperture stop S when focusing on an infinite object at the wide-angle end HIM: Maximum image height when focusing on an infinite object at the wide-angle end

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

When the lower limit of conditional expression (1) is exceeded and the distance on the optical axis from the most image-side surface of the lens group GP on the front side of the diaphragm to the aperture diaphragm S during focusing on an object at infinity at the wide-angle end becomes small, the in-focus condition While suppressing the refractive power of the lens group GF, it becomes difficult to form an image of the aperture diaphragm S seen from the focusing lens group GF at a distance, and aberrations due to fluctuations in image height during wobbling and changes in the focal position occur. It becomes impossible to suppress both fluctuations.

When the upper limit of conditional expression (1) is exceeded and the distance on the optical axis from the most image-side surface of the lens group GP on the front side of the stop to the aperture stop S when focusing on an object at infinity at the wide-angle end becomes large, the in-focus state The height of the principal ray in the lens group GF becomes high, making it difficult to suppress fluctuations in aberration due to changes in the focusing position. It becomes difficult to reduce the weight of the driving part.

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

Further, it is desirable that the wide-angle lens system of the present invention further satisfies the following conditional expression.
(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 lens group GP on the front side of the stop to the 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 of the sensitivity of the imaging plane when the focusing lens group 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 plane when the focusing lens group GF moves during focusing on an object at infinity at the wide-angle end increases, the amount of movement of the focusing lens group becomes small. Therefore, even a slight movement of the focusing lens group causes a large movement of the imaging plane, making it difficult to drive and control the focusing lens group GF within the AF focusing range.

When the upper limit of conditional expression (2) is exceeded and the sensitivity of the imaging plane when the focusing lens group GF moves during focusing on an object at infinity at the wide-angle end becomes small, the amount of movement of the focusing group becomes large. , the fluctuation .DELTA.h of the principal ray height of the focusing lens group due to wobbling becomes large, so that the effect of suppressing the image height fluctuation is weakened, making it difficult to suppress the image height fluctuation during wobbling. Furthermore, a space must be secured before and after the focusing lens group GF, which makes it 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 achieved more reliably. By setting the upper limit of conditional expression (2) to −0.40, the effect of the present invention can be achieved more reliably.

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

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

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

When the upper limit of conditional expression (3) is exceeded and the refractive power of the focusing lens group GF becomes strong, fluctuations in the height of the paraxial principal ray in the group closer to the object side than the focusing lens group due to wobbling become large. Since the aberration generated in the focusing lens group GF itself is also worsened, it becomes difficult to suppress both the image height fluctuation during wobbling and the aberration fluctuation due to the change in the focusing position.

When the lower limit of conditional expression (3) is exceeded and the refractive power of the focusing lens group GF becomes weak, the sensitivity of the imaging plane when the focusing lens group moves becomes small. It becomes difficult not to exceed the upper limit.

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

When the upper limit of conditional expression (4) is exceeded and the refracting power of the lens group GP on the front side of the aperture is increased, it is necessary to increase the negative refracting power of the first lens group G1 in order to maintain a wide angle of view. As a result, it becomes difficult to suppress the aberration occurring in the first lens group G1.

When the lower limit of conditional expression (4) is exceeded and the refractive power of the lens group GP on the front side of the diaphragm becomes weak, the distance between the focusing lens group GF and the aperture diaphragm and the positive refractive power of the focusing lens group GF are suppressed. At the same time, it becomes difficult to form an image of the aperture diaphragm seen from the focusing lens group GF at a distance.

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

In the wide-angle lens system of the present invention, the first lens group G1 has four or more lenses having negative refractive power, three or more of which are meniscus lenses having surfaces having positive refractive power facing the object side. A lens is desirable.

Having four or more lenses having negative refractive power in the first lens group G1 makes it easy to maintain a necessary back focus while maintaining a wide angle of view. In addition, three or more of the lenses having negative refractive power are meniscus lenses with a convex surface facing the object side, so that the angle of deviation between the incident surface and the exit surface for light rays incident on the peripheral image height is reduced. This makes it easy to suppress deterioration of distortion caused by a surface with negative refractive power.

Further, in the wide-angle lens system of the present invention, the subsequent lens group GR has a cemented surface that faces a convex surface 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 plane side. It is desirable to have four or more pairs of lenses.

When the number of cemented lenses in the succeeding lens group GR, which have a convex surface facing 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 3 or less, coma aberration and spherical aberration, it becomes difficult to correct the other. However, by arranging four or more pairs of such cemented lenses, it becomes easy to correct coma and spherical aberration in a well-balanced manner.

Further, in the wide-angle lens system of the present invention, it is desirable that the lens closest to the image plane in the subsequent lens group GR has an aspherical surface.

By arranging an aspherical surface on the lens closest to the image plane side of the succeeding lens group GR, it becomes easy to give an effect to the peripheral light flux while suppressing the influence of the aspherical surface on the axial light flux, thereby affecting the spherical aberration. It becomes easy to correct coma and astigmatism while suppressing .

Next, lens configurations, numerical examples, and values corresponding to conditional expressions of examples of the wide-angle lens system of the present invention will be described. In the following description, the lens configuration will be described in order from the object side to the image plane side. Also, the notation of 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 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 for the d-line (wavelength 587.56 nm). The refractive index, vd is the Abbe number for the d-line, and θgF is the partial dispersion ratio between the g-line (wavelength 435.84 nm) and the F-line (wavelength 486.13 nm).

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

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

[Aspheric surface data] shows the value of each coefficient that gives the aspheric shape of the lens surface marked with * in [Surface data]. The shape of the aspheric surface is represented by the following formula. In the following formula, y is the displacement from the optical axis in the direction orthogonal to the optical axis, z is the displacement (sag amount) in the optical axis direction from the intersection of the aspherical surface and the optical axis, r is the radius of curvature of the reference spherical surface, K represents the conic coefficient. A3, A4, A5, A3, A4, A5 and When placed at A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, and A20, the coordinates of the aspherical 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 Spacing Data] shows the variable spacing and BF values in each focal length state.

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

In the aberration diagrams corresponding to each example, d, g, and C represent the d-line, g-line, and C-line, respectively, and ΔS and ΔM represent the sagittal image plane and meridional image plane, respectively. .

In addition, in the values of all the specifications below, unless otherwise specified, millimeters (mm) are used for the focal length f, radius of curvature r, distance between lens surfaces d, and other lengths. The system is not limited to this because the same optical performance can be obtained in both proportional enlargement and proportional reduction.

FIG. 1 is a lens configuration diagram of a wide-angle lens system according to Example 1 of the present invention.
Example 1 is a variable magnification optical system, which is composed of, in order from the object side, a first lens group G1 having negative refractive power and a subsequent lens group GR having positive refractive power as a whole. It is composed of, in order from the side, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens group G4 with positive refractive power. An aperture diaphragm S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture diaphragm 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 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, and a negative meniscus lens L3 with a convex surface facing the object side. It is composed of a biconcave 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 predetermined aspherical shapes. It's becoming

The second lens group G2 is composed of 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 in order from the object side. The second lens group G2 as a whole moves toward the image plane when focusing from an infinite object distance to a short distance.

The third lens group G3 is composed of 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 and a biconvex lens L10 in order from the object side.

The fourth lens group G4 is composed of a biconvex lens L11, a cemented lens composed of a negative meniscus lens L12 having a convex surface facing the object side and a biconvex lens L13, and 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 aspheric shape.

Further, in the wide-angle lens system of Example 1, 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 distance between the second lens group G2 and the third lens group decreases. After the distance from G3 increases, it 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, the specification values of the wide-angle lens system according to Example 1 are shown 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 side 5 sides 6 sides
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 planes 32 planes
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 Example 2 of the present invention.
Example 2 is a variable magnification optical system, which is composed of, in order from the object side, a first lens group G1 having negative refractive power and a subsequent lens group GR having positive refractive power as a whole. It is composed of, in order from the side, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens group G4 with positive refractive power. An aperture diaphragm S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture diaphragm 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 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, and a negative meniscus lens L3 with a convex surface facing the object side. It is composed of 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 aspherical shape.

The second lens group G2 is composed of 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 in order from the object side. The second lens group G2 as a whole moves toward the image plane when focusing from an infinite object distance to a short distance.

The third lens group G3 is composed of a cemented lens composed of a biconvex lens L8 and a biconcave lens L9, and a positive meniscus lens L10 having a convex surface facing the object side. Both lens surfaces of the positive meniscus lens L10 have a predetermined aspheric shape.

The fourth lens group G4 is cemented with 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 cemented lens consisting of a negative meniscus lens L14 with a convex surface facing the object side and a biconvex lens L15, a cemented lens consisting of a biconcave lens L16 and a positive meniscus lens L17 with 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 aspheric shape.

Further, in the wide-angle lens system of Example 2, 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 distance between the second lens group G2 and the third lens group decreases. After the distance from G3 increases, it 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, the specification values of the wide-angle lens system according to Example 2 are shown 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 side 5 sides 6 sides
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 sides 18 sides
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 planes 32 planes
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
Reference example 3

FIG. 15 is a lens configuration diagram of a wide-angle lens system of Reference Example 3 of the present invention.
Reference Example 3 is a variable power optical system, which is composed of, in order from the object side, a first lens group G1 having negative refractive power and a subsequent lens group GR having positive refractive power as a whole. Consists of, in order from the side, the second lens group G2 with negative refractive power, the third lens group G3 with positive refractive power, the fourth lens group G4 with positive refractive power, and the fifth lens group G5 with positive refractive power. be done. An aperture diaphragm S is arranged between the fourth lens group G4 and the fifth lens group G5, and the aperture diaphragm S moves integrally 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 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, and a negative meniscus lens L3 with a convex surface facing the object side. It is composed of a biconcave 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 predetermined aspherical shapes. It's becoming

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

The third lens group G3 is composed of 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 in order from the object side. The third lens group G3 as a whole moves toward the image plane when focusing from an infinite object distance to a short distance.

The fourth lens group G4 is composed of a positive meniscus lens L9 having a convex surface facing the object side, and a cemented lens composed of a biconcave lens L10 and a biconvex lens L11. Both lens surfaces of the positive meniscus lens L9 have a predetermined aspheric shape.

The fifth lens group G5 is cemented with 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 consisting of a negative meniscus lens L15 with a convex surface facing the object side and a positive meniscus lens L16 with a convex surface facing the object side; and a cemented lens consisting of a biconcave lens L17 and a positive meniscus lens L18 with 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.

In addition, in the wide-angle lens system of Reference Example 3, 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 distance between the fourth lens group G4 and the fifth lens group decreases. The interval with G5 is reduced. 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 during focusing at infinity.

Next, the specification values of the wide-angle lens system according to Reference Example 3 are shown below.
Numerical reference 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 side 5 sides 6 sides
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 sides 17 sides
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 planes 34 planes
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 magnification optical system, which is composed of, in order from the object side, a first lens group G1 having negative refractive power and a subsequent lens group GR having positive refractive power as a whole. It is composed of, in order from the side, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens group G4 with positive refractive power. An aperture diaphragm S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture diaphragm 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 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, and a negative meniscus lens L3 with a convex surface facing the object side. It is composed of a biconcave 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 predetermined aspherical shapes. It's becoming

The second lens group G2 is composed of a biconvex lens L6. The second lens group G2 as a whole moves toward the image plane when focusing from an infinite object distance to a short distance. Both lens surfaces of the biconvex lens L6 have a predetermined aspheric shape.

The third lens group G3 is composed of a cemented lens composed of a biconvex lens L7 and a biconcave lens L8, and a cemented lens composed of 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. It is

The fourth lens group G4 includes a biconvex lens L11, a cemented lens composed of 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 lens 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 and 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 aspheric shape.

Further, in the wide-angle lens system of Example 4, 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 distance between the second lens group G2 and the third lens group decreases. The distance from G3 increases, and the distance between the third lens group G3 and the fourth lens group G4 decreases.

Next, the specification values of the wide-angle lens system according to Example 4 are shown 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 side 5 sides 6 sides
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 sides 12 sides
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 planes 32 planes
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
Reference example 5

FIG. 29 is a lens configuration diagram of a wide-angle lens system of Reference Example 5 of the present invention.
Reference Example 5 is a variable magnification optical system, which is composed of, in order from the object side, a first lens group G1 having negative refractive power and a subsequent lens group GR having positive refractive power as a whole. It is composed of, in order from the side, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens group G4 with positive refractive power. An aperture S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture diaphragm 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 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, and a negative meniscus lens L3 with a convex surface facing the object side. It is composed of a biconcave 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 predetermined aspherical shapes. It's becoming

The second lens group G2 is composed of 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 in order from the object side. The second lens group G2 as a whole moves toward the image plane when focusing from an infinite object distance to a short distance.

The third lens group G3 is composed of 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 and a biconvex lens L10 in order from the object side.

The fourth lens group G4 is composed of a biconvex lens L11, a cemented lens composed of a negative meniscus lens L12 having a convex surface facing the object side and a biconvex lens L13, and 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 aspheric shape.

Further, in the wide-angle lens system of Reference Example 5, 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 distance between the second lens group G2 and the third lens group decreases. After the distance from G3 increases, it 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, the specification values of the wide-angle lens system according to Reference Example 5 are shown below.
Numerical reference 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 side 5 sides 6 sides
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 planes 32 planes
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

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist.

Values corresponding to the conditional expressions corresponding to the above-described examples and reference examples are shown below.
Conditional expression/Example /reference example EX1 EX2 EX3 EX4 EX5
(1) DPS/HIM 0.43 0.43 0.32 0.45 0.47
(2) MRW^2 x (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 diaphragm 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 : Front lens group C C line (wavelength λ = 656.3 nm)
d d line (wavelength λ=587.6 nm)
gg line (wavelength λ = 435.8 nm)
Y image height ΔS sagittal image plane ΔM medional image plane

Claims (9)

In order from the object side, it is composed of a first lens group G1 having negative refractive power and a subsequent lens group GR having positive refractive power as a whole,
The rear lens group GR has an aperture stop S, a front lens group GP on the object side of the aperture stop, and a focusing lens group GF that moves when focusing on the object side,
The lens group GP on the front side of the diaphragm and the focusing lens group GF have positive refractive power. Decreased,
A wide-angle lens system characterized by satisfying the following conditional expressions (1)', (2) and (4)'.
(1)'0.32≤DPS/HIM<1.00
(2) -1.00<MRW^2*(1-MFW^2)<-0.30
(4)'0.096≤√(fw×ft)/fP<0.15
however,
DPS: Distance on the optical axis from the most image-side surface of the lens group GP on the front side of the stop to the aperture stop S when focusing on an infinite object at the wide-angle end HIM: Maximum image height when focusing on an infinite object at the wide-angle end 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 fw from the lens group GP on the front side of the stop to the optical surface closest to the image side when focusing on an object at infinity at the wide-angle end : Focal length of the entire lens system when shooting at infinity at the wide-angle end ft: Focal length of the entire lens system when shooting at infinity at the telephoto end fP: Focal length of the lens group GP on the front side of the aperture
In order from the object side, it is composed of a first lens group G1 having negative refractive power and a subsequent lens group GR having positive refractive power as a whole,
The rear lens group GR has an aperture stop S, a front lens group GP on the object side of the aperture stop, and a focusing lens group GF that moves when focusing on the object side,
The lens group GP on the front side of the diaphragm and the focusing lens group GF have positive refractive power. Decreased,
The succeeding lens group GR has four or more cemented lenses whose cemented surfaces are convex toward the object side and in which the refractive index of the medium on the object side is higher than the refractive index of the medium on the image plane side,
A wide-angle lens system characterized by satisfying the following conditional expressions (1) and (4).
(1) 0.28<DPS/HIM<1.00
(4) 0.04<√(fw×ft)/fP<0.20
however,
DPS: Distance on the optical axis from the most image-side surface of the lens group GP on the front side of the stop to the aperture stop S when focusing on an infinite object at the wide-angle end HIM: Maximum image height when focusing on an infinite object at the wide-angle end fw: focal length of the entire lens system when shooting at infinity at the wide-angle end ft: focal length of the entire lens system when shooting at infinity at the telephoto end fP: focal length of the lens group GP on the front side of the aperture
In order from the object side, it is composed of a first lens group G1 having negative refractive power and a subsequent lens group GR having positive refractive power as a whole,
The rear lens group GR has an aperture stop S, a front lens group GP on the object side of the aperture stop, and a focusing lens group GF that moves when focusing on the object side,
The lens group GP on the front side of the diaphragm and the focusing lens group GF have positive refractive power. Decreased,
The total angle of view 2ω at the wide-angle end is 114.20° or more,
The succeeding lens group GR has four or more cemented lenses whose cemented surfaces are convex toward the object side and in which the refractive index of the medium on the object side is higher than the refractive index of the medium on the image plane side,
A wide-angle lens system characterized by satisfying the following conditional expressions (1) and (2).
(1) 0.28<DPS/HIM<1.00
(2) -1.00<MRW^2*(1-MFW^2)<-0.30
however,
DPS: Distance on the optical axis from the most image-side surface of the lens group GP on the front side of the stop to the aperture stop S when focusing on an infinite object at the wide-angle end HIM: Maximum image height when focusing on an infinite object at the wide-angle end 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 lens group GP on the front side of the stop to the optical surface closest to the image side when focusing on an object at infinity at the wide-angle end
3. The wide-angle lens system according to claim 2, 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 lens group GP on the front side of the stop to the optical surface closest to the image side when focusing on an object at infinity at the wide-angle end
3. The wide-angle lens system according to claim 1, wherein the following conditional expression (3) is satisfied.
(3) 0.10<√(fw×ft)/fF<0.50
however,
fw: focal length of the entire lens system when shooting at infinity at the wide-angle end ft: focal length of the entire lens system when shooting at infinity at the telephoto end fF: focal length of the focusing lens group GF
4. A wide-angle lens system according to claim 3, which satisfies the following conditional expressions (3) and (4).
(3) 0.10<√(fw×ft)/fF<0.50
(4) 0.04<√(fw×ft)/fP<0.20
however,
fw: focal length of the entire lens system when shooting at infinity at the wide-angle end ft: focal length of the entire lens system when shooting at infinity at the telephoto end fF: focal length of the focusing lens group GF fP: the lens group on the front side of the aperture GP focal length
The first lens group G1 has four or more lenses having negative refractive power, three or more of which are meniscus lenses having a convex surface facing the object side. 7. The wide-angle lens system according to any one of items 6.
The succeeding lens group GR has four or more sets of cemented lenses whose cemented surfaces are convex toward the object side and whose refractive index of the medium on the object side is higher than the refractive index of the medium on the image plane side. 8. The wide-angle lens system according to any one of claims 1, 5, and 7 , wherein
9. The wide-angle lens system according to claim 1, wherein the lens closest to the image plane of said subsequent lens group GR has an aspherical surface.

Images