JP7295312B2 - Imaging lens system and imaging device - Google Patents

Description

The present invention relates to a wide-angle imaging lens system and imaging apparatus.

2. Description of the Related Art In recent years, there has been a demand for a lens that supports a wide field of view as an imaging lens system for use in automobiles. 2. Description of the Related Art Imaging lens systems for use in automobiles include, for example, imaging lens systems used in in-vehicle cameras for checking the front, back, and sides to ensure safety when driving an automobile.

An imaging lens system for an on-vehicle camera is required to have an extremely wide field of view, high resolution, and a bright F value of about 2.0. Compactness is also required for imaging lens systems for in-vehicle cameras.

Patent Document 1 discloses, in order from the object side, a first lens with negative power, a second lens with negative power, a third lens with positive power, an aperture stop, a fourth lens with positive power, a negative An imaging lens system is described which consists of a fifth lens having a power of .

JP 2014-89241 A

The imaging lens system described in Patent Literature 1 is wide-angle, bright, and has high imaging performance. However, in an imaging lens system used for an on-vehicle camera, it is desired to further reduce the outer diameter of the lens located closest to the object side in order to make it as inconspicuous as possible when mounted on a vehicle. Along with this, as the number of pixels of the image pickup device used increases, higher resolution is required for the image pickup lens system of the vehicle-mounted camera. In order to achieve high resolution, it is necessary to satisfactorily correct curvature of field in the area from the center to the periphery of the image sensor.

The present invention provides a wide-angle imaging lens and an imaging apparatus equipped with a wide-angle imaging lens that has a smaller outer diameter of the lens located closest to the object side, suppresses curvature of field, and achieves high resolution from the center to the periphery. intended to

The wide-angle imaging lens system of the present invention is
From the object side,
a negative first lens concave to the image side;
a meniscus-shaped second lens concave toward the object side;
a positive third lens having a biconvex shape near the optical axis;
Aperture and
a fourth lens that is a negative lens;
a fifth lens that is a positive lens;
and a sixth lens, at least one of which has an aspherical surface.

In the wide-angle imaging lens system of the present invention, the effective diameter of the first lens can be reduced by making the second lens concave on the object side. Further, by forming the second lens into a meniscus shape with a concave surface facing the object side, curvature of field can be corrected, so excellent imaging performance can be obtained. As a result, it is possible to provide a wide-angle imaging lens system in which the outer diameter of the lens arranged closest to the object side is made smaller, the curvature of field is further suppressed, and the resolution is high from the center to the periphery.

The wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (1), where f1 is the focal length of the first lens and f3 is the focal length of the third lens.
0.8<|f1/f3|<1.2 (1)

According to this configuration, by satisfying conditional expression (1), coma aberration and curvature of field are suppressed while ensuring a long back focus, and the overall length of the lens system is not lengthened. If the upper limit of conditional expression (1) is exceeded, the positive power of the third lens becomes greater than the negative power of the first lens, so that the image plane tilts and it becomes difficult to lengthen the back focus. If the lower limit of conditional expression (1) is exceeded, the negative power of the first lens becomes greater than the positive power of the third lens. As the length increases, the power of the first lens increases, making it difficult to correct aberrations.

Also, the wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (2).
0.9<|f1/f3|<1.1 (2)

The wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (3), where f is the focal length of the entire system and f2 is the focal length of the second lens.
0<f/f2<0.2 (3)

Conditional expression (3) is a conditional expression for performing image plane correction. If the lower limit of conditional expression (3) is not reached with the concave surface facing the object side, the negative power of the second lens increases, so distortion increases, making it difficult to control the angle of view. If the upper limit of conditional expression (3) is exceeded, the positive power of the second lens increases, which increases image surface tilt and degrades imaging performance. Therefore, according to this configuration, by satisfying conditional expression (3), it is possible to prevent an increase in distortion and perform image plane correction.

Also, the wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (4).
0.05<f/f2<0.15 (4)

The wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (5), where f4 is the focal length of the fourth lens and f5 is the focal length of the fifth lens.
-1.8<f4/f5<-1.0 (5)

Conditional expression (5) is a conditional expression for correcting chromatic aberration. If the lower limit of conditional expression (5) is not reached, the negative power of the fourth lens becomes smaller than the positive power of the fifth lens, so chromatic aberration correction becomes insufficient and imaging performance deteriorates. If the upper limit of conditional expression (5) is exceeded, the negative power of the fourth lens becomes greater than the positive power of the fifth lens, so chromatic aberration correction becomes excessive and imaging performance deteriorates. Therefore, according to this configuration, by satisfying conditional expression (5), appropriate chromatic aberration correction can be performed, and deterioration of imaging performance can be prevented.

Also, the wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (6).
-1.6<f4/f5<-1.2 (6)

The wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (7), where f is the focal length of the entire system and f1 is the focal length of the first lens.
1.8<|f1/f|<2.1 (7)

Conditional expression (7) defines the total length of the imaging lens system. If the lower limit of conditional expression (7) is not reached, the negative power of the first lens becomes greater than the power of the entire lens system, resulting in an increase in the total length of the imaging lens system. If the upper limit of conditional expression (7) is exceeded, the negative power of the first lens becomes smaller than the power of the entire lens system, making it difficult to ensure a predetermined back focus. Therefore, according to this configuration, by satisfying conditional expression (7), it is possible to ensure a predetermined back focus while preventing an increase in the total length of the imaging lens system.

Also, the wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (8).
1.9<|f1/f|<2.0 (8)

The wide-angle imaging lens system of the present invention satisfies the following conditional expression (9), where R2 is the radius of curvature of the image side surface of the first lens and R3 is the radius of curvature of the object side surface of the second lens. preferable.
-1.2<R2/R3<-0.4 (9)

Conditional expression (9) defines coma, curvature of field and distortion. If the lower limit of conditional expression (9) is not reached, the image surface will tilt, making it difficult to correct curvature of field. If the upper limit of conditional expression (9) is exceeded, distortion will increase, making it difficult to control the angle of view. Therefore, according to this configuration, by satisfying conditional expression (9), it is possible to correct field curvature and prevent an increase in distortion.

Also, the wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (10).
-1.0<R2/R3<-0.6 (10)

In the wide-angle imaging lens system of the present invention, f1 is the focal length of the first lens, f23 is the combined focal length of the second lens and the third lens, and f23 is the focal length of the first lens, the second lens, and the third lens. When the Abbe numbers are νd1, νd2, and νd3, respectively, it is preferable to satisfy the following conditional expressions (11) and (12).
-1.1<f1/f23<-0.9 (11)
35<(νd1+νd2+νd3)/3<60 (12)

By satisfying the conditional expression (11), the wide-angle imaging lens system of the present invention can secure the back focus while keeping the overall length of the imaging lens system short, and can perform good chromatic aberration correction. If the upper limit of conditional expression (11) is exceeded, it is advantageous for securing the back focus, but it becomes difficult to correct chromatic aberration and the total length of the imaging lens system becomes long. If the lower limit of conditional expression (11) is not reached, the correction of chromatic aberration becomes excessive and it becomes difficult to secure the back focus. Further, by simultaneously satisfying conditional expressions (11) and (12), good chromatic aberration correction becomes possible.

The wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (13), where f is the focal length of the entire system and f23 is the combined focal length of the second lens and the third lens.
1.3<f23/f<1.65 (13)

By satisfying the conditional expression (13), the wide-angle imaging lens system of the present invention can secure a long back focus and can perform good chromatic aberration correction. If the lower limit of conditional expression (13) is not reached, it is effective in reducing axial chromatic aberration and chromatic aberration of magnification, but it becomes difficult to secure the back focus. If the upper limit of conditional expression (13) is exceeded, it becomes easier to lengthen the back focus, but it becomes difficult to satisfactorily correct chromatic aberration.

Also, the wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (14).
1.4<f23/f<1.55 (14)

The imaging device of the present invention is
the imaging lens system described above;
and an imaging element arranged at a focal position of the imaging lens system.

According to the present invention, the outer diameter of the lens arranged closest to the object side is made smaller, the curvature of field is further suppressed, and the resolution is high from the center to the periphery. can be provided.

1 is a cross-sectional view of an imaging lens system according to Example 1. FIG. 4 is an aberration diagram of the imaging lens system according to Example 1. FIG. FIG. 11 is a cross-sectional view of an imaging lens system according to Example 2; FIG. 10 is an aberration diagram of the imaging lens system according to Example 2; FIG. 11 is a cross-sectional view of an imaging lens system according to Example 3; FIG. 11 is an aberration diagram of an imaging lens system according to Example 3; 1 is a cross-sectional view of an imaging device according to an embodiment; FIG.

Examples of the wide-angle imaging lens system 11 according to the embodiment of the present invention will be described below.

[Example 1]
FIG. 1 is a diagram showing the configuration of a wide-angle imaging lens system 11 of Example 1. As shown in FIG. As shown in FIG. 1, the wide-angle imaging lens system 11 of Example 1 includes, in order from the object side, a first lens L1 having a concave shape on the image side and having negative power, and a lens L1 having a concave surface facing the object side. A second lens L2 having a meniscus shape, a third lens L3 having a biconvex shape near the optical axis Z and having positive power, an aperture stop STOP, a fourth lens L4 having negative power, and a positive power. and a sixth lens L6 having at least one aspherical surface. The imaging plane of the wide-angle imaging lens system 11 is indicated by IMG. In the wide-angle imaging lens system 11 of Example 1, the second lens L2, the fourth lens L4, the fifth lens L5 and the sixth lens L6 are plastic lenses, and the first lens L1 and the third lens L3 are glass lenses. .

The first lens L1 is a spherical meniscus lens with negative power. The object-side lens surface S1 of the first lens L1 is a flat surface, and the image-side lens surface S2 is a spherical surface having a positive curvature. The image-side lens surface S2 has a concave curved surface portion that is recessed toward the object side.

The second lens L2 is an aspherical lens with positive power. The object-side lens surface S3 of the second lens L2 is an aspherical surface having a negative curvature, and the image-side lens surface S4 is an aspherical surface having a negative curvature. The object-side lens surface S3 has a concave curved surface portion that is recessed toward the image side. The image-side lens surface S4 has a convex curved surface portion that protrudes toward the image side.

The third lens L3 is a spherical lens with positive power. The object-side lens surface S5 is a spherical surface with positive curvature, and the image-side lens surface S6 is a spherical surface with negative curvature. The object-side lens surface S5 has a convex curved surface portion projecting toward the object side, and the image-side lens surface S6 has a convex curved surface portion projecting toward the image side.

The first lens L1 has the function of converting incident light rays from large angles of incidence to smaller angles along the optical axis Z. FIG. The image-side lens surface S2 of the first lens L1 has negative power in order to spread light rays. Since the second lens L2 has a meniscus shape with a concave surface facing the object side, it can satisfactorily correct curvature of field. The third lens L3 is a positive lens convex to the object side, and has the function of converging the rays diverged by the first lens L1.

The fourth lens L4 is an aspherical lens with negative power. The object-side lens surface S8 of the fourth lens L4 is an aspherical surface with negative curvature, and the image-side lens surface S9 is an aspherical surface with positive curvature. The object-side lens surface S8 has a concave curved surface that is recessed toward the image side. The image-side lens surface S9 has a concave curved surface that is recessed toward the object side.

The fifth lens L5 is an aspherical lens with positive power. The object-side lens surface S10 of the fifth lens L5 is an aspherical surface with positive curvature, and the image-side lens surface S11 is an aspherical surface with negative curvature. The object-side lens surface S10 has a convex curved surface portion that protrudes toward the object side. The image-side lens surface S11 has a convex curved surface portion that protrudes toward the image side. The object-side lens surface S10 of the fifth lens L5 is adhered to the image-side lens surface S9 of the fourth lens L4 with an adhesive.

The sixth lens L6 is an aspherical lens with negative power. The object-side lens surface S12 of the sixth lens L6 is an aspherical surface with negative curvature, and the image-side lens surface S13 is an aspherical surface with negative curvature. The object-side lens surface S12 has a concave curved surface portion that is recessed toward the image side. The image-side lens surface S13 has a convex curved surface portion that protrudes toward the image side.

The fourth lens L4 is a lens with negative power and large dispersion. The fifth lens L5 is a lens with positive power and small dispersion. Therefore, by combining the fourth lens L4 and the fifth lens L5, longitudinal chromatic aberration and lateral chromatic aberration can be corrected.

The cover glass 12 is a glass plate for protecting the imaging element. The cover glass 12 is handled integrally with the wide-angle imaging lens system 11 when the wide-angle imaging lens system 11 is designed. However, the cover glass 12 is not an essential component of the wide-angle imaging lens system 11 .

Table 1 shows lens data for each lens surface of the wide-angle imaging lens system 11 . As lens data, the radius of curvature of each surface, surface spacing, refractive index, and Abbe number are listed. A surface marked with "*" indicates that it is an aspherical surface.

The aspheric shape adopted for the lens surface is 4th, 6th, 8th, and 10th, where z is the amount of sag, c is the reciprocal of the radius of curvature, k is the conic coefficient, and r is the height of the ray from the optical axis. , 12th, 14th, and 16th aspherical coefficients are A4, A6, A8, A10, A12, A14, and A16, respectively.

Table 2 shows the aspherical coefficients for defining the aspherical shape of the aspherical lens surface in the wide-angle imaging lens system 11 of Example 1. In Table 2, for example, "-1.673481E-03" means "-1.673481×10-3".

2A to 2C are longitudinal aberration diagrams, field curvature diagrams, and distortion aberration diagrams of the wide-angle imaging lens system 11 of Example 1. FIG. As shown in FIGS. 2A to 2C, in the wide-angle imaging lens system 11 of Example 1, the half angle of view ω is 67.5° and the F value is 2.0. In the longitudinal aberration diagram of FIG. 2(a), the horizontal axis indicates the position where the light beam intersects the optical axis Z, and the vertical axis indicates the height at the pupil diameter. In the curvature of field diagram of FIG. 2B, the horizontal axis indicates the distance in the Z direction of the optical axis, and the vertical axis indicates the image height (angle of view). In FIG. 2B, Sag indicates field curvature on the sagittal plane, and Tan indicates field curvature on the tangential plane. In the distortion diagram of FIG. 2(c), the horizontal axis indicates the distortion amount (%) of the image, and the vertical axis indicates the image height (angle of view). FIG. 2(a) shows the simulation results for light beams with wavelengths of 656 nm, 546 nm and 436 nm, and FIGS. 2(b) and (c) show the simulation results for light beams with a wavelength of 546 nm.

Table 3 shows the results of calculating the characteristic values of the wide-angle imaging lens system 11 of Example 1. In the wide-angle imaging lens system 11, the F value is FNo, the distance from the object-side lens surface S1 of the first lens L1 to the imaging plane IMG of the wide-angle imaging lens system 11 is "optical total length", and the focal length of the entire lens system is f , f1 is the focal length of the first lens L1, f2 is the focal length of the second lens L2, f3 is the focal length of the third lens L3, f4 is the focal length of the fourth lens L4, and f5 is the focal length of the fifth lens L5. , and the focal length of the sixth lens L6 is f6. Various focal lengths were calculated using light with a wavelength of 546 nm.

[Example 2]
FIG. 3 is a diagram showing the configuration of the wide-angle imaging lens system 11 of Example 2. As shown in FIG. As shown in FIG. 3, the first to sixth lenses L1 to L6 have the same shape as in the first embodiment. In the wide-angle imaging lens system 11 of Example 2, the second lens L2, the fourth lens L4, the fifth lens L5 and the sixth lens L6 are plastic lenses, and the first lens L1 and the third lens L3 are glass lenses. .

Table 4 shows lens data of each lens surface of the wide-angle imaging lens system 11 of Example 2.

Table 5 shows the aspherical coefficients for defining the aspherical shape of the aspherical lens surface in the wide-angle imaging lens system 11 of Example 2.

4A to 4C are longitudinal aberration diagrams, curvature of field diagrams, and distortion diagrams of the wide-angle imaging lens system 11 of Example 2. FIG. As shown in FIGS. 4A to 4C, in the wide-angle imaging lens system 11 of Example 2, the half angle of view ω is 68.2° and the F value is 2.0.

Table 6 shows the results of calculating the characteristic values of the wide-angle imaging lens system 11 of Example 2.

[Example 3]
FIG. 5 is a diagram showing the configuration of the wide-angle imaging lens system 11 of Example 3. As shown in FIG. The first to fifth lenses L1 to L5 have the same shape as in the first embodiment. The shape of the sixth lens L6 differs from that of the first embodiment.

The sixth lens L6 is an aspherical lens with negative power. The object-side lens surface S12 of the sixth lens L6 is an aspherical surface with negative curvature, and the image-side lens surface S13 is an aspherical surface with positive curvature. The object-side lens surface S12 has a concave curved surface portion in the vicinity of the optical axis Z that is recessed toward the image side. The image-side lens surface S13 has a concave curved surface portion in the vicinity of the optical axis Z that is recessed toward the object side.

In the wide-angle imaging lens system 11 of Example 3, the second lens L2, the fourth lens L4, the fifth lens L5 and the sixth lens L6 are plastic lenses, and the first lens L1 and the third lens L3 are glass lenses. .

Table 7 shows lens data of each lens surface of the wide-angle imaging lens system 11 of Example 3.

Table 8 shows the aspherical coefficients for defining the aspherical shape of the aspherical lens surface in the wide-angle imaging lens system 11 of Example 3.

6A to 6C are longitudinal aberration diagrams, field curvature diagrams, and distortion aberration diagrams of the wide-angle imaging lens system 11 of Example 3. FIG. As shown in FIGS. 6A to 6C, in the wide-angle imaging lens system 11 of Example 3, the half angle of view ω is 67.1° and the F value is 2.0.

Table 9 shows the results of calculating the characteristic values of the wide-angle imaging lens system 11 of Example 3.

[Summary of conditional expressions]
Table 10 shows the calculation results of various parameters used in conditional expressions (1) to (14) in the wide-angle imaging lens systems 11 of Examples 1-3. The composite focal length of the second lens L2 and the third lens L3 is f23, the composite focal length of the fourth lens L4 and the fifth lens L5 is f45, the radius of curvature of the image-side lens surface of the first lens L1 is R2, and the The radius of curvature of the object-side lens surface of the second lens L2 is R3, the Abbe number of the first lens L1 is νd1, the Abbe number of the second lens L2 is νd2, and the Abbe number of the third lens L3 is νd3, and various parameters are calculated. are doing.

As described above, the wide-angle imaging lens system of the present embodiment includes, in order from the object side, a first negative lens concave to the image side, a second meniscus lens concave to the object side, and an optical lens. a positive third lens having a biconvex shape near the axis, an aperture, a fourth lens that is a negative lens, a fifth lens that is a positive lens, and a sixth lens that has at least one aspherical surface; , the effective diameter of the first lens can be reduced by making the second lens concave on the object side. Further, by forming the second lens into a meniscus shape with a concave surface facing the object side, curvature of field can be corrected. As a result, it is possible to provide a wide-angle imaging lens system in which the outer diameter of the lens arranged closest to the object side is made smaller, the curvature of field is further suppressed, and the resolution is high from the center to the periphery.

The wide-angle imaging lens system of the present embodiment satisfies the following conditional expression (1), where f1 is the focal length of the first lens, and f3 is the focal length of the third lens. , while suppressing coma and curvature of field, and the overall length of the lens system is not lengthened.
0.8<|f1/f3|<1.2 (1)

Further, the wide-angle imaging lens system of the present embodiment preferably satisfies the following conditional expression (2).
0.9<|f1/f3|<1.1 (2)

The wide-angle imaging lens system of the present embodiment satisfies the following conditional expression (3), where f is the focal length of the entire system, and f2 is the focal length of the second lens. image plane correction can be performed.
0<f/f2<0.2 (3)

Further, the wide-angle imaging lens system of the present embodiment preferably satisfies the following conditional expression (4).
0.05<f/f2<0.15 (4)

The wide-angle imaging lens system of the present embodiment satisfies the following conditional expression (5), where f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens. Correction can be performed to prevent deterioration of imaging performance.
-1.8<f4/f5<-1.0 (5)

Moreover, the wide-angle imaging lens system of the present embodiment preferably satisfies the following conditional expression (6).
-1.6<f4/f5<-1.2 (6)

The wide-angle imaging lens system of this embodiment satisfies the following conditional expression (7), where f is the focal length of the entire system, and f1 is the focal length of the first lens. A predetermined back focus can be ensured while preventing an increase in .
1.8<|f1/f|<2.1 (7)

Further, the wide-angle imaging lens system of the present embodiment preferably satisfies the following conditional expression (8).
1.9<|f1/f|<2.0 (8)

The wide-angle imaging lens system of this embodiment satisfies the following conditional expression (9), where R2 is the radius of curvature of the image side surface of the first lens and R3 is the radius of curvature of the object side surface of the second lens. As a result, coma and curvature of field can be corrected, and an increase in distortion can be prevented.
-1.2<R2/R3<-0.4 (9)

Further, the wide-angle imaging lens system of the present embodiment preferably satisfies conditional expression (10) below.
-1.0<R2/R3<-0.6 (10)

In the wide-angle imaging lens system of the present embodiment, the focal length of the first lens is f1, the combined focal length of the second lens and the third lens is f23, the first lens, the second lens, the third lens By satisfying the following conditional expressions (11) and (12) where the Abbe numbers of the lenses are νd1, νd2, and νd3, respectively, it is possible to secure the back focus while keeping the overall length of the imaging lens system short. Chromatic aberration correction becomes possible.
-1.1<f1/f23<-0.9 (11)
35<(νd1+νd2+νd3)/3<60 (12)

The wide-angle imaging lens system of the present embodiment satisfies the following conditional expression (13), where f is the focal length of the entire system, and f23 is the combined focal length of the second lens and the third lens. , a long back focus can be ensured, and good chromatic aberration correction is possible.
1.3<f23/f<1.65 (13)

Further, the wide-angle imaging lens system of the present embodiment preferably satisfies conditional expression (14) below.
1.4<f23/f<1.55 (14)

[Example of application to imaging device]
FIG. 7 is a diagram showing the configuration of an imaging device 10 using the wide-angle imaging lens system 11. As shown in FIG. The imaging device 10 has a wide-angle imaging lens system 11 , a cover glass 12 and an imaging device 13 . The wide-angle imaging lens system 11, the cover glass 12, and the imaging element 13 are housed in a housing (not shown).

The imaging element 13 is an element that converts received light into an electric signal, and for example, a CCD image sensor or a CMOS image sensor is used. The imaging element 13 is arranged at the focal position of the wide-angle imaging lens system 11 . Note that the horizontal angle of view is the angle of view corresponding to the horizontal direction of the imaging device 13 .

A cover glass 12 is provided on the imaging element 13 to protect the imaging element 13 from foreign matter.

It should be noted that the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the scope of the invention. For example, the application of the wide-angle imaging lens system 11 of the present invention is not limited to an in-vehicle camera, but can also be used for other applications such as surveillance cameras and cameras mounted on small electronic devices such as mobile phones. .

10 imaging device 11 wide-angle imaging lens system 12 cover glass 13 imaging elements L1 to L6 first lens to sixth lens

Claims (7)

From the object side,
a negative first lens concave to the image side;
a meniscus-shaped second lens concave toward the object side;
a positive third lens having a biconvex shape near the optical axis;
Aperture and
a fourth lens that is a negative lens;
a fifth lens that is a positive lens;
and a sixth lens concave to the object side ,
A wide-angle imaging lens system , wherein an object-side lens surface of the fourth lens has a negative curvature . 2. The wide-angle imaging lens system according to claim 1, wherein the object-side lens surface of said fourth lens is an aspherical surface. 2. The wide-angle imaging lens system according to claim 1, wherein at least one surface of said fifth lens is an aspherical surface. 2. A wide-angle imaging lens system according to claim 1, wherein said sixth lens is a negative lens. 2. The wide-angle imaging lens system according to claim 1, wherein the image-side lens surface of said sixth lens has a negative curvature. 2. The wide-angle imaging lens system according to claim 1, wherein at least one surface of said sixth lens is an aspherical surface. An image pickup apparatus comprising: the image pickup lens system according to claim 1; and an image sensor arranged at a focal position of the image pickup lens system.

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