JP6609956B2 - Fisheye lens - Google Patents

Description

  The present invention relates to a fish-eye lens used in an imaging apparatus such as a digital camera or a video camera.

  In recent years, with an interchangeable lens camera, not only still image shooting but also moving image shooting can be easily performed, and the demand for moving image shooting has increased. Among them, an interchangeable lens suitable for moving image shooting is preferred.

  Among them, the fish-eye lens has a different projection method from a normal lens and can obtain a special depiction using negative distortion. This special description is sometimes used as an expression method. Therefore, a fisheye lens suitable for moving image shooting is desired.

  In addition, it is desired that the F number is small in order to improve convenience in shooting in a dark place or night view shooting.

  Therefore, a fisheye lens having a small F number and suitable for moving image shooting is required.

  As a fisheye lens, it is disclosed by patent document 1 thru | or patent document 5, for example.

International Publication No. 2011/0777716 JP 2012-022109 A JP 2004-126522 A JP2013-238684A JP 2006-017837 A

  In Patent Document 1 and Patent Document 2, the focus lens is lightweight, which is advantageous for reducing noise during focusing and suitable for moving image shooting, but the F-number is as large as about 3.5 to 4.0. Next, in Patent Document 3 and Patent Document 4, the F number is about 2.8 and 1.8, but since the focus lens is large, it is difficult to reduce noise during focusing. Further, in Patent Document 5, the F number is about 1.8 and there is little aberration and high performance, but this is not preferable because the optical system is large.

  In order to reduce the F number of the optical system disclosed in Patent Documents 1 and 2, there is no power in the lens configuration in the vicinity of the aperture, and when the F number is decreased, the refractive power of the light beam of the lens before and after the aperture is strong. As a result, performance degradation due to manufacturing errors such as lens decentration increases.

  That is, in order to reduce the F number, it is necessary to reduce the performance degradation due to manufacturing errors of the lenses before and after the aperture stop.

  Next, it is difficult to use the optical system disclosed in Patent Document 3 and Patent Document 4 for focusing only a part of the lens groups because of large aberration fluctuations during focusing. This is because it is desirable for the focus lens to have a small aberration fluctuation during focusing and to be light in weight.

  In addition, during moving image recording, an image during focusing is also recorded. Therefore, if the change in the size of the image due to the movement of the focus lens is large, it may be unpleasant and unfavorable. Therefore, it is desirable that the change in the size of the image due to the movement of the focus lens is small.

  In order to reduce the size of the optical system disclosed in Patent Document 5, there is no power in the lens configuration and it is difficult to correct aberrations. Although an increase in the size of the lens is advantageous for aberration correction, it is not preferable as an interchangeable lens because portability deteriorates.

  In order to reduce the F-number in the miniaturized imaging optical system as described above, it is necessary to consider reducing the amount of performance degradation due to manufacturing errors of the focus group which is a movable group. In order to reduce the size of the product, it is necessary to reduce the actuator for driving the focus group, so the focus lens group needs to be lightweight. In order to reduce the weight, it is desirable to use a single focusing lens as in Patent Documents 3 and 4, but doing so will cause an eccentric coma due to a manufacturing error, resulting in a decrease in performance from the center image height. In order to reduce the eccentric frame due to the manufacturing error, the refractive power of the focus lens may be lowered. However, the amount of movement at the time of focusing must be increased, and downsizing becomes difficult.

  An object of the present invention is to provide a fisheye lens having a small F number, a small size, a wide angle of view, suitable for moving image shooting, and good AF performance and optical performance.

The first invention, which is a means for solving the above-mentioned problems, has a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a positive refractive power in order from the object side. The first lens group G1 includes, in order from the object side, a first N1 lens group G1N1 having a negative refractive power and a first N2 lens group G1N2 having a negative refractive power. The 1N1 lens group G1N1 includes a first negative meniscus lens L1N1 that is convex toward the object side in order from the object side, a second negative meniscus lens L2N1 that is convex toward the object side, and the first N2 lens group G1N2 is concave toward the object side. The third lens group G3 includes a 3a lens group G3a, an aperture stop S, and a 3b lens group G3b in order from the object side . In focus The first lens group G1 and the third lens group G3 are fixed with respect to the image plane, and the second lens group G2 moves to the image side, and satisfies the following conditional expression: Fisheye lens.
The fish-eye lens of the present invention is an optical system in which the distortion at the half angle of view ω = 90 ° is −100% in the central projection method, and the principal ray for calculating the distortion is the center of the aperture stop S. Is defined as a ray passing through.
(1) 0.10 <(L1N1R1-L1N1R2) / (L1N1R1 + L1N1R2) <1.00
(2) 0.10 <(L2N1R1-L2N1R2) / (L2N1R1 + L2N1R2) <1.00
(3) 0.15 <L3N2R1 / fL3N2 <4.00
(4) 8.0 <f2 / f <45.0
(8) 2.80 <EXP / f <20.00
(11) 0.05 <D2S / LT <0.60
(12) 1.30 <f3a / f <12.50
(13) 1.40 <f3b / f <10.00
L1N1R1: Object-side radius of curvature L1N1R2 of the first negative meniscus lens L1N1: Image-side radius of curvature L2N1R1 of the first negative meniscus lens L1N1: Object-side radius of curvature L2N1R2 of the second negative meniscus lens L2N1: Second negative meniscus lens Image side radius of curvature L3N2R1 of L2N1: Object side radius of curvature fL3N2 of the negative lens L3N2: Focal length f of the negative lens L3N2: Focal length f2 of the entire system at infinity shooting: Focal length EXP of the second lens group G2 : Distance from exit pupil position to image plane when focusing on infinity
D2S: Distance from the final surface of the second lens group G2 to the aperture stop S when focusing on infinity
LT: distance from the top surface of the first lens group G1 to the image plane
f3a: focal length of the third-a lens group G3a
f3b: Focal length of the third b lens group G3a

The second invention, which is a means for solving the above-mentioned problems, is the fisheye lens according to the first invention, and the first lens group G1 has negative refractive power in order from the object side. 2. The first N1 lens group G1N1, a first P1 lens group G1P1 having a positive refractive power, and a first N2 lens group G1N2 having a negative refractive power, satisfying the following conditions: Fisheye lens.
(5) 4.00 <f1P1 / f <70.00
f: focal length of the entire system at infinity shooting f1P1: focal length of the first P1 lens group G1P1

A third invention, which is a means for solving the above-mentioned problems, is a fisheye lens according to the first invention or the second invention, and further satisfies the following conditions.
(6) -2.40 <f1 / f <-0.70
(7) -5.00 <fN12 / f <-1.00
(8) 2.80 <EXP / f <20.00
(9) 0.05 <D13 / LT <0.45
(10) 1.40 <f3 / f <6.50
f: Focal length of the entire system at infinity shooting f1: Focal length of the first lens group G1 fN12: Composite focal length EXP from the first negative meniscus lens L1N1 to the second negative meniscus lens L2N1: Infinite distance Distance from the exit pupil position during focusing to the image plane D13: Distance from the final surface of the first lens group G1 to the top surface of the third lens group G3 LT: Image plane from the top surface of the first lens group G1 Distance f3: focal length of the third lens group G3

A fourth invention, which is a means for solving the above-mentioned problems, is a fisheye lens according to any one of the first to third inventions, and further has an aspheric surface in the second lens group G2. A fisheye lens characterized by that.

A fifth invention, which is means for solving the above-mentioned problems, is a fish-eye lens according to any one of the first to fourth inventions, and is means for solving the above-mentioned problems. A sixth invention is a fish-eye lens according to any one of the first to fifth inventions, wherein the third lens group G3b is for a d-line (wavelength λ = 587.56 nm) of a medium of a positive lens. A fisheye lens comprising two or more lenses having a positive refractive power greater than 60 Abbe number.

  According to the present invention, it is possible to provide a fisheye lens having a small F number, a small size, a wide angle of view, suitable for moving image shooting, and good AF performance and optical performance.

It is a lens block diagram in the infinite distance which concerns on Example 1 of this invention. FIG. 6 is a longitudinal aberration diagram at an imaging distance infinite according to Example 1 of the present invention. FIG. 6 is a longitudinal aberration diagram at an imaging distance of 118 mm in Example 1 of the present invention. FIG. 3 is a lateral aberration diagram at infinite shooting distance according to Example 1 of the present invention. It is a lens block diagram in the infinite distance which concerns on Example 2 of this invention. FIG. 6 is a longitudinal aberration diagram at an imaging distance infinite according to Example 2 of the present invention. FIG. 6 is a longitudinal aberration diagram at an imaging distance of 126 mm in Example 2 of the present invention. It is a lateral aberration diagram at the photographing distance infinite distance of Example 2 of the present invention. It is a lens block diagram in the infinite distance which concerns on Example 3 of this invention. FIG. 6 is a longitudinal aberration diagram at an imaging distance infinity according to Example 3 of the present invention. FIG. 6 is a longitudinal aberration diagram at an imaging distance of 118 mm in Example 3 of the present invention. It is a lateral aberration diagram at the shooting distance infinite distance of Example 3 of the present invention. It is a lens block diagram in the infinite distance which concerns on Example 4 of this invention. It is a longitudinal aberration figure in the photographic distance infinite distance of Example 4 of this invention. FIG. 6 is a longitudinal aberration diagram at an imaging distance of 105 mm in Example 4 of the present invention. It is a lateral aberration figure in Example 4 of this invention in the shooting distance infinite distance. It is a lens block diagram in the infinite distance which concerns on Example 5 of this invention. FIG. 10 is a longitudinal aberration diagram at an imaging distance infinity according to Example 5 of the present invention. FIG. 6 is a longitudinal aberration diagram at an imaging distance of 118 mm in Example 5 of the present invention. FIG. 10 is a lateral aberration diagram at an imaging distance infinity according to Example 5 of the present invention. It is a lens block diagram in the infinite distance which concerns on Example 6 of this invention. It is a longitudinal aberration figure in the photographic distance infinite distance of Example 6 of this invention. FIG. 10 is a longitudinal aberration diagram at an imaging distance of 118 mm in Example 6 of the present invention. It is a lateral aberration diagram at the shooting distance infinite distance of Example 6 of the present invention. It is a lens block diagram in the infinite distance which concerns on Example 7 of this invention. FIG. 12 is a longitudinal aberration diagram at an imaging distance infinity according to Example 7 of the present invention. FIG. 10 is a longitudinal aberration diagram at an imaging distance of 120 mm in Example 7 of the present invention. It is a lateral aberration diagram at the shooting distance infinite in Example 7 of the present invention. FIG. 10 is a lens configuration diagram at infinity according to Reference Example 8 of the present invention. It is a longitudinal aberration figure in the photographing distance infinite of reference example 8 of this invention. It is a longitudinal aberration figure in photographing distance 118mm of reference example 8 of the present invention. It is a lateral aberration figure in photographing distance infinity of the reference example 8 of this invention.

As can be seen from the lens configuration diagrams shown in FIG. 1, FIG. 5, FIG. 9, FIG. 13, FIG. 17, FIG. , A first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power. The first lens group G1 is in order from the object side. A first negative meniscus having a first N1 lens group G1N1 having a negative refractive power and a first N2 lens group G1N2 having a negative refractive power, the first N1 lens group G1N1 being convex toward the object side in order from the object side. The lens L1N1 has a second negative meniscus lens L2N1 having a convex side facing the object side, and the first N2 lens group G1N2 has a negative lens L3N2 having a concave side facing the object side, so that an object from an infinite object to a short distance object can be obtained. When focusing, the first lens group 1 and the third lens group G3 is fixed relative to an image surface, the second lens group G2 has a configuration that moves toward the image side. Furthermore, it is desirable that the imaging optical system of the present invention satisfies the following conditional expression.
(1) 0.10 <(L1N1R1-L1N1R2) / (L1N1R1 + L1N1R2) <1.00
(2) 0.10 <(L2N1R1-L2N1R2) / (L2N1R1 + L2N1R2) <1.00
(3) 0.15 <L3N2R1 / fL3N2 <4.00
(4) 8.0 <f2 / f <45.0
L1N1R1: Object-side radius of curvature L1N1R2 of the first negative meniscus lens L1N1 in the first N1 lens group G1N1: Image-side radius of curvature L2N1R1 of the first negative meniscus lens L1N1 in the first N1 lens group G1N1: Object-side radius of curvature L2N1R2 of the second second negative meniscus lens L2N1 in the first N1 lens group G1N1: Image-side radius of curvature L3N2R1 of the second second meniscus lens L2N1 in the first N1 lens group G1N1: First N2 Object-side radius of curvature fL3N2 of the negative lens L3N2 in the lens group G1N2: Focal length f of the negative lens L3N2 in the first N2 lens group G1N2: Focal length f2 of the entire system at infinity shooting: the second lens group G2 Focal length

  Conditional expression (1) and conditional expression (2) define the lens shape for realizing a wide angle of view as a fisheye lens. By appropriately setting the lens shape, it is possible to correct aberrations satisfactorily while obtaining a sufficient wide angle of view.

  When the upper limit of conditional expression (1) is exceeded and the curvature on the object side becomes small, the negative refractive power becomes strong and it becomes difficult to correct astigmatism and coma. When the upper limit is exceeded and the object-side curvature decreases, the lens diameter increases. As a result, the diameter of the product becomes large, which is not preferable. When the lower limit of conditional expression (1) is exceeded and the object-side curvature increases, the refractive power becomes weak and the amount of negative distortion generated decreases, making it difficult to obtain the angle of view as a fisheye lens.

  Regarding conditional expression (1), the lower limit value is desirably limited to 0.40, and the upper limit value is preferably limited to 0.70, whereby the above-described effect can be further ensured.

  When the upper limit of the conditional expression (2) is exceeded and the curvature on the object side becomes small, the negative refractive power becomes strong and it becomes difficult to correct astigmatism and coma. When the upper limit is exceeded and the object-side curvature decreases, the lens diameter increases. As a result, the diameter of the product becomes large, which is not preferable. When the lower limit of conditional expression (2) is exceeded and the object-side curvature increases, the refractive power becomes weak and the amount of negative distortion generated decreases, making it difficult to obtain the angle of view as a fisheye lens.

  Regarding conditional expression (2), desirably, the lower limit value is preferably limited to 0.11 and the upper limit value is limited to 0.85, whereby the above-described effect can be further ensured.

  Conditional expression (3) defines the shape of the negative lens in the first N2 lens group G1N2. Good aberration correction is possible by appropriately setting the shape of the negative lens in the first N2 lens group G1N2.

  If the upper limit of conditional expression (3) is exceeded and the negative refractive power increases, the aberration balance with the adjacent second lens group deteriorates, making it difficult to correct coma and spherical aberration during focusing. If the lower limit of conditional expression (3) is exceeded and the curvature on the object side becomes strong, correction of astigmatism and coma becomes difficult.

  Regarding conditional expression (3), desirably, the lower limit value is desirably limited to 0.25, and the upper limit value is desirably limited to 2.50, whereby the above-described effects can be further ensured.

  Conditional expression (4) defines an appropriate focal length of the second lens group. Good aberration correction can be achieved by appropriately setting the focal length of the second lens group.

If the upper limit of conditional expression (4) is exceeded and the refractive power of the second lens group G2 becomes weak, the amount of movement used for focusing increases, and the lens system becomes large. As a result, the total length of the product becomes long, which is not preferable. If the lower limit of conditional expression (4) is exceeded and the refractive power of the second lens group G2 becomes strong, it becomes difficult to correct astigmatism and coma during focusing. Also, it becomes difficult to correct spherical aberration during close-up photography. Further, it is not preferable because it is difficult to reduce the change in magnification of the image during focusing.

  Regarding conditional expression (4), the lower limit value is desirably limited to 10.0, and the upper limit value is desirably limited to 30.0, so that the above-described effect can be further ensured.

The imaging optical system according to the second aspect of the present invention is the first aspect, wherein the first lens group G1 is positively refracted with the first N1 lens group G1N1 having negative refractive power in order from the object side. A fish-eye lens comprising a first P1 lens group G1P1 having power and a first N2 lens group G1N2 having negative refractive power, and satisfying the following conditional expression:
(5) 4.00 <f1P1 / f <70.00
f: focal length of the entire system at infinity shooting f1P1: focal length of the first P1 lens group G1P1

  The first lens group G1 of the fish-eye lens according to the second aspect of the invention includes a first N1 lens group G1N1 having a negative refractive power in order from the object side, a first P1 lens group G1P1 having a positive refractive power, and a negative refractive power. And a first N2 lens group G1N2. By adopting such a configuration, it is possible to correct aberrations satisfactorily and to reduce the diameter of the second lens G2. It is possible to reduce the weight by reducing the diameter of the second lens group G2, and it is possible to calm down during focusing.

  Conditional expression (5) defines the focal length of the first P1 lens group G1P1. By appropriately setting the focal length of the first P1 lens group G1P1, it becomes possible to correct aberrations satisfactorily, and the diameter of the second lens group G2 is reduced because the beam diameter is reduced by the positive refractive power of the first P1 lens group G1P1. Can be set appropriately, and the weight of the focus lens can be reduced and the noise can be reduced during focusing.

  If the upper limit of conditional expression (5) is exceeded and the refractive power of the first P1 lens group G1P1 becomes weak, the diameter of the second lens group G2 used for focusing increases and the weight increases. An increase in weight is not preferable because smooth focusing suitable for moving image shooting becomes difficult. If the lower limit of conditional expression (5) is exceeded and the refractive power of the first P1 lens group G1P1 becomes strong, correction of astigmatism and coma becomes difficult.

  Regarding conditional expression (5), the lower limit value is desirably limited to 4.50, and the upper limit value is limited to 45.00, so that the above-described effect can be further ensured.

The fisheye lens according to the third invention is the first invention or the second invention, and further satisfies the following conditional expression.
(6) -2.40 <f1 / f <-0.70
(7) -5.00 <fN12 / f <-1.00
(8) 2.80 <EXP / f <20.00
(9) 0.05 <D13 / LT <0.45
(10) 1.40 <f3 / f <6.50
f: Focal length of the entire system at infinity shooting f1: Focal length of the first lens group G1 fN12: Composite focal length EXP from the first negative meniscus lens L1N1 to the second negative meniscus lens L2N1: Infinite distance Distance from the exit pupil position during focusing to the image plane D13: Distance from the final surface of the first lens group G1 to the top surface of the third lens group G3 LT: Image plane from the top surface of the first lens group G1 Distance f3: focal length of the third lens group G3

  Conditional expression (6) defines an appropriate focal length of the first lens group G1. By appropriately setting the focal length of the first lens group G1, a wide angle of view can be obtained and good aberration correction can be performed.

  If the upper limit of conditional expression (6) is exceeded and the refractive power of the first lens group G1 becomes weak, a wide angle of view cannot be secured. When the lower limit of conditional expression (6) is exceeded and the refractive power of the first lens group G1 increases, it becomes difficult to correct off-axis astigmatism and coma.

  Regarding conditional expression (6), the lower limit value is desirably limited to -1.70 and the upper limit value is desirably limited to -0.90, whereby the above-described effect can be further ensured.

  Conditional expression (7) defines an appropriate value of the combined focal length from the first negative meniscus lens L1N1 having a convex toward the object side in order from the object side to the second negative meniscus lens L2N1 having a convex toward the object side. Is. By appropriately setting the combined focal length of the first negative meniscus lens L1N1 having convex toward the object side and the second negative meniscus lens L2N1 having convex toward the object side, a wide angle of view can be obtained and good aberration correction can be achieved. It becomes possible.

  When the refractive power of the combined focal length fN12 of the second negative meniscus lens L2N1 having the convex side toward the object side from the first negative meniscus lens L1N1 having the convex side toward the object side exceeding the upper limit of the conditional expression (7) increases, Astigmatism correction becomes difficult. When the refractive power of the combined focal length fN12 of the second negative meniscus lens L2N1 having the convex side toward the object side from the first negative meniscus lens L1N1 having the convex side toward the object side exceeding the lower limit of the conditional expression (7) is reduced, the wide angle of view. It becomes difficult to secure.

  Regarding conditional expression (7), the lower limit value is desirably limited to −3.50, and the upper limit value is desirably limited to −1.10, whereby the above-described effect can be further ensured.

Conditional expression (8) defines the exit pupil position. By appropriately setting the exit pupil position, the incident condition of the light beam to the image sensor becomes appropriate, and it becomes possible to suppress a decrease in peripheral light amount. Furthermore, it becomes possible to reduce the change in magnification of the image during focusing.

  When the upper limit of conditional expression (8) is exceeded and the position of the aperture is far away from the image plane, the chief ray moves away from the center of the light beam to the upper ray side, making it difficult to correct astigmatism. In addition, since the distance between the stop and the second lens group G2 becomes narrow, it becomes difficult to reduce the change in image magnification during focusing, which is not preferable. Further, maintaining the position of the principal ray is not preferable because the total length becomes long and the lens system becomes large. When the lower limit of conditional expression (8) is exceeded and the position of the stop is close to the image plane, the exit angle of the off-axis ray with respect to the image plane increases. This is not preferable because the incidence of light rays on the image sensor becomes insufficient and the peripheral light amount decreases greatly.

  Regarding conditional expression (8), desirably, the lower limit value is desirably limited to 4.00 and the upper limit value is limited to 15.00, whereby the above-described effects can be further ensured.

  Conditional expression (9) defines the lens interval from the first lens group G1 to the third lens group G3. By setting an appropriate lens interval, a sufficient amount of movement of the second lens group G2, which is a focus group, is obtained, so that a lens interval suitable for focusing is obtained, and favorable focusing is obtained.

  If the upper limit of conditional expression (9) is exceeded, the lens system becomes large. In particular, since the diameter of the first lens group becomes large, the lens weight increases and the diameter of the product also becomes unfavorable. Alternatively, the peripheral luminous flux is scattered at the outer edge of the lens, which is not preferable because the peripheral light amount is reduced. When the lower limit of conditional expression (9) is exceeded, the amount of movement for use in focusing decreases. Therefore, it is not preferable because the close-up shooting distance is shortened.

  Regarding conditional expression (9), desirably, the lower limit value is desirably limited to 0.10 and the upper limit value is limited to 0.30, whereby the above-described effect can be further ensured.

  Conditional expression (10) defines an appropriate focal length of the third lens group. By appropriately setting the focal length of the third lens group, it is possible to correct aberrations satisfactorily.

  If the upper limit of conditional expression (10) is exceeded and the refractive power of the third lens group G3 becomes weak, the back focus becomes long and the lens system becomes large, which is not preferable. If the lower limit of conditional expression (10) is exceeded and the refractive power of the third lens group G3 becomes strong, it becomes difficult to correct spherical aberration, coma aberration, and astigmatism. In addition, since the back focus is shortened, it is difficult to use the camera with an interchangeable lens camera.

  Regarding conditional expression (10), the lower limit value is desirably limited to 2.00, and the upper limit value is desirably limited to 4.50, whereby the above-described effect can be further ensured.

In the fisheye lens according to the first aspect of the invention, the third lens group G3 includes the third a lens group G3a, the aperture stop S, and the third b lens group G3b in order from the object side, and further satisfies the following conditional expression: A fish-eye lens.
(11) 0.05 <D2S / LT <0.60
(12) 1.30 <f3a / f <12.50
(13) 1.40 <f3b / f <10.00
D2S: Distance from the final surface of the second lens group G2 to the aperture stop S at the time of focusing on infinity LT: Distance from the leading surface of the first lens group G1 to the image plane f3a: of the 3a lens group G3a Focal length f3b: focal length of the third b lens group G3a

  Conditional expression (11) defines an appropriate lens interval from the second lens group G2 to the stop surface. It is possible to reduce the change in magnification of the image during focusing.

  If the upper limit of conditional expression (11) is exceeded, the lens system becomes large. In particular, since the diameter of the first lens group becomes large, the lens weight increases and the diameter of the product also becomes unfavorable. When the lower limit of conditional expression (11) is exceeded, it is difficult to reduce the change in image magnification during focusing, which is not preferable.

  Regarding conditional expression (11), the lower limit value is desirably limited to 0.15, and the upper limit value is preferably limited to 0.45, whereby the above-described effect can be further ensured.

  Conditional expression (12) defines an appropriate focal length for G3a of the 3a lens group. By setting the 3a lens group G3a to an appropriate focal length, it is possible to correct aberrations satisfactorily.

  When the upper limit of conditional expression (12) is exceeded and the refractive power of the third-a lens group G3a becomes weak, the diameter from the stop to the lens on the image side increases. This is not preferable because it is difficult to reduce the lens diameter after reducing the F value. If the lower limit of conditional expression (12) is exceeded and the refractive power of the third-a lens group G3a becomes strong, correction of spherical aberration and coma becomes difficult.

  Regarding conditional expression (12), the lower limit value is desirably limited to 1.80, and the upper limit value is preferably limited to 9.00, whereby the above-described effect can be further ensured.

  Conditional expression (13) defines an appropriate focal length of the third lens group G3b. Good aberration correction is possible by appropriately setting the focal length of the third lens group G3b.

  When the upper limit of conditional expression (13) is exceeded and the refractive power of the third lens group G3b becomes weak, the lateral magnification of the third lens group G3b increases, and the image circle expands. Therefore, it becomes difficult to ensure a wide angle of view. If the lower limit of conditional expression (13) is exceeded and the refractive power of the third lens group G3b is increased, it will be difficult to correct spherical aberration, coma and astigmatism.

  Regarding conditional expression (13), the lower limit value is desirably limited to 2.00 and the upper limit value is preferably limited to 6.80, whereby the above-described effect can be further ensured.

The fisheye lens according to the fourth invention is any one of the first invention to the third invention, and preferably has an aspheric surface in the second lens group G2.

  It is preferable to use an aspheric surface in the second lens group, since it is possible to suppress a variation in spherical aberration accompanying the focus.

A fisheye lens according to a fifth invention is any one of the first invention to the fourth invention, and the third b lens group G3b has a d-line (wavelength λ = 587.56 nm) of a medium of a positive lens. ) Having two or more lenses having a positive refractive power greater than 60.

  6th invention prescribes | regulates the Abbe number of the lens which has the positive refractive power of the 3b lens group G3b. Good chromatic aberration correction can be achieved by appropriately setting the Abbe number of the lens having the positive refractive power of the third lens group G3b.

  If the Abbe number of the lens having the positive refractive power of the third lens group G3b is small, it is difficult to correct axial chromatic aberration and lateral chromatic aberration.

  Note that at least one positive lens among a plurality of lenses having a positive refractive power greater than 60 with respect to the d-line (wavelength λ = 587.56 nm) of the positive lens medium of the third lens group G3b. By making the Abbe number of a lens having a refractive power of 80 or more, the above-described effect can be further ensured.

  Next, the lens configuration of an example relating to the fisheye lens of the present invention will be described. In the following description, the lens configuration is described in order from the object side to the image 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 surface, d is the distance between the surfaces, nd is the refractive index with respect to the d-line (wavelength 587.56 nm). , Vd represents the Abbe number of the d line, and the effective radius represents the ray height.

The * (asterisk) attached to the surface number indicates that the lens surface shape is an aspherical surface. BF represents back focus, and the object distance represents the distance from the subject to the first lens surface.

  The (diaphragm) attached to the surface number indicates that the aperture stop S is located at that position. In addition, ∞ (infinity) is written in the curvature radius with respect to the plane and the aperture stop S.

[Aspherical data] indicates the aspherical coefficient indicating the aspherical coefficient giving the aspherical shape of the lens surface marked with * in [Surface data]. The aspherical shape is a displacement from the optical axis in the direction perpendicular to the optical axis. Y, the displacement (sag amount) in the optical axis direction from the intersection of the aspheric surface and the optical axis to z, the radius of curvature of the reference spherical surface to r, the conic coefficient to K, 4, 6, 8, and the 10th-order aspheric coefficient. Assume that the coordinates of the aspheric surface are expressed by the following equations when A4, A6, A8, and A10 are set, respectively.

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

[Variable interval data] indicates the value of the variable interval and BF (back focus) in each focal length state.

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

  Further, in the lens configuration diagrams shown in FIGS. 1, 5, 9, 13, 17, 21, 25, and 29, I is the image plane, F is the filter, and the alternate long and short dash line is the optical axis. is there.

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

  FIG. 1 is a lens configuration diagram of a fisheye lens according to Example 1 of the present invention. In order from the object side, the first lens group G1 has a negative refractive power, G2 has a positive refractive power, and a third lens group G3 has a positive refractive power. The first lens group G1 is convex on the object side. A negative first meniscus lens L1N1 having a negative refractive power and a negative meniscus lens L2N1 having a convex surface facing the object side, and a first N2 lens group G1N2 having a negative refractive power comprising a negative lens L3N2. The second lens group G2 is composed of a cemented lens of a biconvex lens having an aspheric object side surface and a negative meniscus lens having a concave surface facing the object side. The third lens group G3 includes a biconvex lens and an object side. A 3a lens group G3a composed of a positive meniscus lens having a convex surface facing the lens, an aperture stop S, a cemented lens composed of a biconvex lens and a biconcave lens, and a surface facing the image side with the concave surface facing the object side. A positive meniscus lens that is an aspherical surface, a positive meniscus lens having a convex surface facing the object side, a cemented lens composed of a biconvex lens and a negative meniscus lens having a concave surface facing the object side, and a plano-convex lens 1 having a convex surface facing the object side The third lens group G3b, and the first lens group G1 and the third lens group G3 are fixed with respect to the image plane when focusing from an object at infinity to an object at a short distance. The lens group G2 moves to the image side.

  A filter F that is a plane-parallel plate is disposed between the third lens group G3 and the image plane. The position of the filter F on the optical axis does not affect the aberration anywhere between the third lens group G3 and the image plane.

Subsequently, specification values of the fisheye lens according to Example 1 are shown below.
Numerical example 1
Unit: mm
[Surface data]
Surface number rd nd vd
1 48.4677 2.0000 1.95374 32.31
2 16.4558 6.4150
3 19.5735 1.0000 1.77250 49.60
4 15.1298 9.5851
5 -40.6798 0.8000 1.77250 49.60
6 34.1908 (d6)
7 * 322.2158 2.5522 1.80610 40.71
8 -46.7155 0.8000 1.84666 23.77
9 -217.8973 (d9)
10 135.3517 2.0727 2.00100 29.12
11 -93.4675 0.1500
12 39.5439 2.3089 2.00100 29.12
13 432.3531 8.6135
14 (Aperture) ∞ 3.5682
15 15.3353 3.5815 1.43700 95.06
16 -588.4382 0.8000 1.92118 23.95
17 16.6963 2.3339
18 -128.4920 2.0872 1.59201 67.00
19 * -33.5016 0.1500
20 28.5725 2.5655 1.43700 95.06
21 346.6105 0.1500
22 27.7324 4.7601 1.43700 95.06
23 -34.4468 0.8000 1.84666 23.77
24 -1200.6303 0.1500
25 28.8372 3.4352 1.61800 63.37
26 ∞ 12.6900
27 ∞ 4.0000 1.51633 64.12
28 ∞ (BF)

[Aspherical data]
7 sides 19 sides
K 0.0000 0.0000
A4 -1.0963E-08 5.4115E-06
A6 -7.8814E-08 6.7276E-08
A8 5.7615E-10 -2.9617E-09
A10 -2.6633E-12 2.1057E-11

[Various data]
INF 118mm
Focal length 7.90 7.64
F number 1.82 1.83
Full angle of view 2ω 197.32 197.32
Image height Y 11.62 11.75

[Variable interval data]
Shooting distance INF 118mm
d6 5.3233 12.2310
d9 10.3077 3.4000
BF 1.0000 1.0000

[Lens group data]
Group Start surface Focal length
G1 1 -8.17
G2 7 181.63
G3 10 24.38
G1N1 1 -19.64
G1P1--
G1N2 5 -23.94
G3a 10 24.45
G3b 15 33.66

  FIG. 6 is a lens configuration diagram of a fisheye lens according to Example 2 of the present invention.

  In order from the object side, the first lens group G1 has a negative refractive power, G2 has a positive refractive power, and a third lens group G3 has a positive refractive power. The first lens group G1 is convex on the object side. A negative meniscus lens L1N1 having a negative refractive power and a negative meniscus lens L3N2 having a negative refractive power facing the object side and a negative meniscus lens L3N2 having a negative refractive power facing the object side. The second lens group G2 includes a cemented lens of a biconvex lens having an aspheric object side surface and a negative meniscus lens having a concave surface facing the object side. The group G3 includes a biconvex lens, a negative meniscus lens having a concave surface directed toward the object side, a biconvex lens, and a third a lens group G3a including a cemented lens of the biconvex lens and the biconcave lens. It comprises an aperture stop S, a cemented lens of a biconvex lens and a biconcave lens, a biconvex lens whose both surfaces are aspherical surfaces, and a planoconvex lens having a convex surface facing the object side, and a third b lens group G3b lens group. When focusing from an object to a short distance object, the first lens group G1 and the third lens group G3 are fixed with respect to the image plane, and the second lens group G2 moves to the image side.

  A filter F that is a plane-parallel plate is disposed between the third lens group G3 and the image plane. The position of the filter F on the optical axis does not affect the aberration anywhere between the third lens group G3 and the image plane.

Subsequently, specification values of the fisheye lens according to Example 2 are shown below.
Numerical example 2
Unit: mm
[Surface data]
Surface number rd nd vd
1 45.7831 2.5374 1.88300 40.79
2 14.8495 9.4879
3 59.5138 1.0000 1.88300 40.79
4 16.6361 9.0173
5 -22.4968 0.8000 1.72916 54.65
6 -40.0935 (d6)
7 * 761.0281 3.0000 1.77250 49.44
8 -29.8776 0.8000 1.84666 23.77
9 -75.5105 (d9)
10 93.8953 2.6417 2.00271 19.31
11 -66.9202 1.0314
12 -25.8186 0.8000 2.00100 29.12
13 -209.7411 0.1500
14 67.5307 3.6066 1.95374 32.31
15 -33.3050 0.1500
16 19.4215 5.4740 1.84666 23.77
17 -25.9874 0.8000 1.92285 20.87
18 16.3563 3.4887
19 (Aperture) ∞ 5.8507
20 15.1580 4.3407 1.43700 95.06
21 -26.3728 0.8000 1.85477 24.79
22 29.9346 1.8556
23 * 34.0355 3.6647 1.61880 63.83
24 * -45.2061 0.1500
25 19.0543 5.1036 1.43700 95.06
26 ∞ 12.6898
27 ∞ 4.0000 1.51633 64.12
28 ∞ (BF)

[Aspherical data]
7 faces 23 faces 24 faces
K 0.0000 0.0000 0.0000
A4 2.2439E-06 -3.8022E-05 5.3694E-06
A6 -1.2325E-07 1.3153E-07 2.1036E-07
A8 1.0702E-09 1.2142E-10 -3.4986E-09
A10 -5.5666E-12 3.2297E-11 6.1608E-11

[Various data]
INF 126mm
Focal length 7.90 7.66
F number 1.82 1.82
Full angle of view 2ω 196.62 196.62
Image height Y 11.60 11.68

[Variable interval data]
Shooting distance INF 126mm
d6 3.5000 6.8808
d9 6.2599 2.8791
BF 1.0000 1.0000

[Lens group data]
Group Start surface Focal length
G1 1 -8.34
G2 7 102.70
G3 10 24.95
G1N1 1 -11.06
G1P1--
G1N2 5 -71.67
G3a 10 29.61
G3b 20 25.75

  FIG. 11 is a lens configuration diagram of a fisheye lens according to Example 3 of the present invention. In order from the object side, the first lens group G1 has a negative refractive power, G2 has a positive refractive power, and a third lens group G3 has a positive folding power. The first lens group G1 is convex on the object side. A first N1 lens group G1N1 having a negative refracting power composed of a negative meniscus lens L1N1 having a convex surface and a negative meniscus lens L2N1 having a convex surface facing the object side, and a first N2 lens group having a negative refracting power composed of a biconcave lens L3N2. The second lens group G2 is composed of a cemented lens of a biconvex lens and a biconcave lens whose surface on the object side is aspheric, and the third lens group G3 is a third a lens group G3a composed of a biconvex lens. A cemented lens comprising an aperture stop S, a positive meniscus lens having a convex surface facing the object side, a positive meniscus lens 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 biconvex lens and a biconcave lens whose surface on the object side is aspheric, a biconvex lens, a positive meniscus lens having a convex surface on the object side, and a planoconvex lens with a convex surface on the object side The third lens group G3b lens group, and the first lens group G1 and the third lens group G3 are fixed with respect to the image plane during focusing from an object at infinity to a short distance object, and the second lens The group G2 moves to the image side.

A filter F that is a plane-parallel plate is disposed between the third lens group G3 and the image plane. The position of the filter F on the optical axis does not affect the aberration anywhere between the third lens group G3 and the image plane.

Subsequently, specification values of the fisheye lens according to Example 3 are shown below.
Numerical example 3
Unit: mm
[Surface data]
Surface number rd nd vd
1 68.5809 2.7126 1.77250 49.60
2 14.6209 9.6347
3 40.3780 1.0000 2.00100 29.12
4 21.5961 6.6701
5 -27.5885 0.8000 1.43700 95.06
6 145.6654 (d6)
7 * 56.3669 3.0000 1.80610 40.71
8 -76.8607 0.8000 1.84666 23.77
9 141.4865 (d9)
10 63.6834 1.9567 1.94594 17.98
11 -181.1242 5.9387
12 (Aperture) ∞ 4.8031
13 22.8193 3.2949 1.59282 68.60
14 1455.9698 1.2791
15 17.5009 3.6013 1.43700 95.06
16 123.9900 0.8000 1.84666 23.77
17 22.1812 2.2912
18 * 24.2369 2.8758 1.59201 67.00
19 -153.9818 0.8000 1.80518 25.45
20 19.7358 1.2406
21 52.2373 2.4274 1.59282 68.60
22 -84.0275 0.1500
23 32.3457 1.8025 1.43700 95.06
24 55.4756 0.1500
25 31.1562 3.0768 1.61800 63.37
26 ∞ 12.6900
27 ∞ 4.0000 1.51633 64.12
28 ∞ (BF)

[Aspherical data]
7 18
K 0.0000 0.0000
A4 -1.4179E-06 -3.6913E-05
A6 -6.4781E-08 -2.0837E-07
A8 6.1458E-10 5.4521E-09
A10 -2.6026E-12 -6.9470E-11
A12-3.00030E-13

[Various data]
INF 118mm
Focal length 7.91 7.64
F number 1.82 1.83
Full angle of view 2ω 197.32 197.32
Image height Y 11.60 11.66


[Variable interval data]
Shooting distance INF 118mm
d6 3.2000 10.1135
d9 12.0046 5.0911
BF 1.0000 1.0000

[Lens group data]
Group Start surface Focal length
G1 1 -9.49
G2 7 125.32
G3 10 22.67
G1N1 1 -14.20
G1P1--
G1N2 5 -53.00
G3a 10 50.00
G3b 13 26.33

  FIG. 16 is a lens configuration diagram of the fisheye lens according to Example 4 of the present invention. In order from the object side, the first lens group G1 has a negative refractive power, G2 has a positive refractive power, and a third lens group G3 has a positive refractive power. The first lens group G1 is convex on the object side. A negative first meniscus lens L1N1 having a negative refractive power and a negative meniscus lens L2N1 having a convex surface facing the object side, and a first N2 lens group G1N2 having a negative refractive power comprising a biconcave lens L3N2. The second lens group G2 is composed of a cemented lens of a biconvex lens and a biconcave lens whose surface on the object side is aspheric, and the third lens group G3 is a positive meniscus lens with a convex surface facing the object side. A 3a lens group G3a, an aperture stop S, a cemented lens of a biconvex lens and a biconcave lens, a positive meniscus lens having a concave surface on the object side and an aspheric surface on the image side, Consisting of a negative meniscus lens having a convex surface facing the body and a positive meniscus lens having a convex surface facing the object side, a positive meniscus lens having a convex surface facing the object side, and a 3b lens group G3b lens group composed of a biconvex lens. When focusing from a distant object to a close object, the first lens group G1 and the third lens group G3 are fixed with respect to the image plane, and the second lens group G2 moves to the image side.

  A filter F that is a plane-parallel plate is disposed between the third lens group G3 and the image plane. The position of the filter F on the optical axis does not affect the aberration anywhere between the third lens group G3 and the image plane.

Subsequently, specification values of the fisheye lens according to Example 4 are shown below.
Numerical example 4
Unit: mm
[Surface data]
Surface number rd nd vd
1 55.3678 2.0000 1.91082 35.24
2 16.1490 10.4325
3 51.9341 1.0000 1.51680 64.17
4 27.9162 5.3378
5 -50.7749 0.8000 1.77250 49.60
6 32.4603 (d6)
7 * 40.4610 2.8931 1.80610 40.71
8 -435.8259 0.8000 1.80808 22.75
9 64.4773 (d9)
10 107.2140 2.4880 1.95374 32.31
11 -70.5853 0.1500
12 31.1323 2.4628 2.00100 29.12
13 149.9812 7.3930
14 (Aperture) ∞ 2.1559
15 22.5073 3.3340 1.43700 95.06
16 -33.3708 0.8000 1.92118 23.95
17 20.1928 1.7477
18 -28.8105 2.1862 1.59201 67.00
19 * -19.4516 0.6198
20 22.9024 0.8000 1.84666 23.77
21 13.7408 4.8384 1.59282 68.60
22 94.1333 0.1500
23 40.6546 1.9400 1.43700 95.06
24 114.8953 0.1500
25 29.9120 3.9648 1.61800 63.37
26 -94.5519 12.6900
27 ∞ 4.0000 1.51633 64.12
28 ∞ (BF)

[Aspherical data]
7 sides 19 sides
K 0.0000 0.0000
A4 -3.9423E-06 -1.1356E-06
A6 -7.3302E-08 7.4438E-07
A8 5.3192E-10 -2.0096E-08
A10 -1.8269E-12 1.5208E-10

[Various data]
INF 105mm
Focal length 7.90 7.62
F number 1.82 1.84
Full angle of view 2ω 196.68 196.68
Image height Y 11.60 11.97

[Variable interval data]
Shooting distance INF 105mm
d6 4.3334 13.7864
d9 13.5326 4.0796
BF 1.0000 1.0000

[Lens group data]
Group Start surface Focal length
G1 1 -8.51
G2 7 126.65
G3 10 24.53
G1N1 1 -19.54
G1P1--
G1N2 5 -25.53
G3a 10 20.92
G3b 15 37.88

  FIG. 21 is a lens configuration diagram of the fisheye lens according to Example 5 of the present invention. In order from the object side, the first lens group G1 has a negative refractive power, G2 has a positive refractive power, and a third lens group G3 has a positive refractive power. The first lens group G1 is convex on the object side. A negative meniscus lens L1N1 having a negative refractive power and a negative meniscus lens L2N1 having a convex surface facing the object side, and a positive meniscus lens having a positive meniscus lens having a convex surface facing the object side. A first P1 lens group G1P1 having a refractive power and a first N2 lens group G1N2 having a negative refractive power composed of a biconcave lens L3N2. The second lens group G2 includes a biconvex lens whose surface on the object side is aspheric and both The third lens group G3 includes a cemented lens of a concave lens, and includes a biconvex lens, a positive meniscus lens having a convex surface facing the object side, and a negative meniscus lens having a convex surface facing the object side. A third-a lens group G3a, an aperture stop S, a biconvex lens, a cemented lens composed of a biconvex lens and a biconcave lens, a biconvex lens having an aspheric object side surface, and a negative meniscus lens having a convex surface facing the object side And a 3b lens group G3b composed of a biconvex lens and a biconvex lens. When focusing from an infinite object to a close object, the first lens group G1 and the third lens group G3 are on the image plane. The second lens group G2 moves to the image side.

  A filter F that is a plane-parallel plate is disposed between the third lens group G3 and the image plane. The position of the filter F on the optical axis does not affect the aberration anywhere between the third lens group G3 and the image plane.

Subsequently, specification values of the fisheye lens according to Example 5 are shown below.
Numerical example 5
Unit: mm
[Surface data]
Surface number rd nd vd
1 52.8269 2.0000 2.00100 29.12
2 16.0322 8.6375
3 29.6732 1.0000 1.77250 49.60
4 20.2235 0.1500
5 20.2235 3.5079 1.43700 95.06
6 23.2948 5.7220
7 -33.0406 0.8000 1.77250 49.60
8 62.4290 (d8)
9 * 78.4558 2.7605 1.80610 40.71
10 -76.8174 0.8000 1.84666 23.77
11 322.4303 (d11)
12 92.7714 3.0594 2.00100 29.12
13 -45.9457 0.1500
14 22.0682 2.3990 2.00100 29.12
15 53.0284 3.7683
16 347.9376 0.8000 1.74950 35.03
17 16.5674 3.3034
18 (Aperture) ∞ 2.0000
19 42.3885 1.9553 1.59282 68.60
20 -140.5558 0.1500
21 18.6643 3.4370 1.49700 81.58
22 -42.1334 0.8000 1.80518 25.45
23 23.9035 2.7283
24 * 27.5771 2.6061 1.59201 67.00
25 -316.8835 0.1500
26 318.5373 0.8000 1.84666 23.77
27 22.7889 0.8031
28 41.6877 3.4409 1.59282 68.60
29 -40.9352 0.1500
30 23.8577 4.6268 1.59282 68.60
31 -113.1889 12.6898
32 ∞ 4.0000 1.51633 64.12
33 ∞ (BF)

[Aspherical data]
9 faces 24 faces
K 0.0000 0.0000
A4 -1.3957E-06 -2.7217E-06
A6 -9.8869E-08 -2.3923E-07
A8 6.6342E-10 9.2238E-09
A10 -2.0259E-12 -7.8119E-11

[Various data]
INF 118mm
Focal length 7.90 7.72
F number 1.82 1.83
Full angle of view 2ω 197.18 197.18
Image height Y 11.60 11.87

[Variable interval data]
Shooting distance INF 118mm
d8 4.0548 10.3960
d11 9.7353 3.3941
BF 1.0000 1.0000

[Lens group data]
Group Start surface Focal length
G1 1 -8.36
G2 9 139.25
G3 12 25.89
G1N1 1 -17.00
G1P1 5 260.52
G1N2 7 -27.87
G3a 12 30.63
G3b 19 22.16

  FIG. 26 is a lens configuration diagram of the fisheye lens according to Example 6 of the present invention. In order from the object side, the first lens group G1 has a negative refractive power, G2 has a positive refractive power, and a third lens group G3 has a positive refractive power. The first lens group G1 is convex on the object side. A positive meniscus lens having a negative refractive power, a negative meniscus lens L1N1 having a negative refractive power, a negative meniscus lens L2N1 having a convex surface facing the object side, and a positive meniscus lens having a convex surface facing the object side. A first P1 lens group G1P1 having a refractive power of 1 and a first N2 lens group G1N2 having a negative refractive power composed of a biconcave lens L3N2, and the second lens group G2 has a convex surface facing the object side and a surface on the object side Consists of a cemented lens composed of a convex meniscus lens that is an aspheric surface and a negative meniscus lens having a concave surface facing the object side. The third lens group G3 has a biconvex lens and a convex surface facing the object side. A positive meniscus lens, a 3a lens group G3a composed of a biconcave lens, an aperture stop S, a positive meniscus lens having a convex surface facing the object side, a cemented lens composed of a biconvex lens and a biconcave lens, and a surface on the object side It is composed of a biconvex lens that is a spherical surface, a negative meniscus lens having a convex surface directed toward the object side, a third convex lens group G3b composed of a biconvex lens, and a biconvex lens. The first lens group G1 and the third lens group G3 are fixed with respect to the image plane, and the second lens group G2 moves to the image side.

  A filter F that is a plane-parallel plate is disposed between the third lens group G3 and the image plane. The position of the filter F on the optical axis does not affect the aberration anywhere between the third lens group G3 and the image plane.

Subsequently, specification values of the fisheye lens according to Example 6 are shown below.
Numerical example 6
Unit: mm
[Surface data]
Surface number rd nd vd
1 51.9522 2.0000 1.91082 35.24
2 15.7673 11.6770
3 154.7074 1.0000 1.77250 49.60
4 26.2369 1.7461
5 32.5637 3.5126 1.78471 25.71
6 250.0000 2.5314
7 -34.1605 0.8000 1.77250 49.60
8 40.4559 (d8)
9 * 34.1938 2.6906 1.80610 40.71
10 1518.5622 0.8000 1.84666 23.77
11 52.5933 (d11)
12 77.1669 3.3285 1.83400 37.33
13 -33.3527 0.1500
14 28.2853 1.9416 2.00100 29.12
15 74.6363 0.7453
16 -134.9961 0.8000 1.48749 70.41
17 17.1670 4.0789
18 (Aperture) ∞ 0.6921
19 26.6998 2.2102 1.43700 95.06
20 78.3216 0.1500
21 19.9079 3.8486 1.43700 95.06
22 -38.9108 0.8000 1.92118 23.95
23 51.8603 5.0433
24 * 37.5876 3.0501 1.59201 67.00
25 -61.4228 0.1500
26 63.3331 0.8000 1.84666 23.77
27 18.9508 1.5887
28 59.0841 2.7884 1.80420 46.48
29 -77.2283 0.1500
30 19.5211 5.1565 1.43700 95.06
31 -1000.0000 12.6900
32 ∞ 4.0000 1.51633 64.12
33 ∞ (BF)

[Aspherical data]
9 faces 24 faces
K 0.0000 0.0000
A4 -8.9405E-06 1.8124E-06
A6 -2.9341E-08 -1.9754E-07
A8 7.2963E-11 5.6708E-09
A10 -8.3780E-13 -5.8138E-11
A12-1.9583E-13

[Various data]
INF 118mm
Focal length 7.89 7.72
F number 1.82 1.83
Full angle of view 2ω 196.04 196.04
Image height Y 11.60 11.91

[Variable interval data]
Shooting distance INF 118mm
d8 3.6539 10.6878
d11 10.9263 3.8924
BF 1.0000 1.0000

[Lens group data]
Group Start surface Focal length
G1 1 -8.61
G2 9 121.48
G3 12 24.06
G1N1 1 -13.35
G1P1 5 47.38
G1N2 7 -23.86
G3a 12 32.44
G3b 19 26.02

  FIG. 31 is a lens configuration diagram of the fisheye lens according to Example 7 of the present invention. In order from the object side, the lens unit includes a first lens group G1 having a negative refractive power, a G2 having a positive refractive power, and a third lens group G3 having a positive refractive power. The first lens group G1 is convex on the object side. A negative meniscus lens L1N1 having a negative refractive power and a negative meniscus lens L2N1 having a convex surface facing the object side. The first N1 lens group G1N1 having a negative refractive power and a first P1 lens group having a positive refractive power consisting of a biconvex lens. G1P1 and a first N2 lens group G1N2 having a negative refractive power composed of a negative meniscus lens L3N2 having a concave surface directed toward the object side. The second lens group G2 includes a biconvex lens whose surface on the object side is an aspheric surface, The third lens group G3 includes a biconcave lens, a biconvex lens, a positive meniscus lens having a convex surface facing the object side, and a negative meniscus lens having a convex surface facing the object side. A third lens group G3a, an aperture stop S, a biconvex lens, a cemented lens composed of a biconvex lens and a biconcave lens, a biconvex lens, a negative meniscus lens having a convex surface facing the object side, a biconvex lens, It consists of a positive meniscus lens having a convex surface facing the object side and a 3b lens group G3b lens group consisting of a plano-convex lens having a convex surface facing the object side. When focusing from an infinite object to a short distance object, The lens group G1 and the third lens group G3 are fixed with respect to the image plane, and the second lens group G2 moves to the image side.

  A filter F that is a plane-parallel plate is disposed between the third lens group G3 and the image plane. The position of the filter F on the optical axis does not affect the aberration anywhere between the third lens group G3 and the image plane.

Subsequently, specification values of the fisheye lens according to Example 7 are shown below.
Numerical example 7
Unit: mm
[Surface data]
Surface number rd nd vd
1 48.0181 2.0000 2.00100 29.12
2 16.1496 11.7878
3 130.0628 1.0000 1.77250 49.60
4 22.9172 4.5849
5 726.7039 3.0085 1.84666 23.77
6 -49.4026 2.5549
7 -23.4133 0.8000 1.77250 49.60
8 -1084.3029 (d8)
9 * 104.7520 2.4840 1.80610 40.71
10 -69.9013 0.8000 1.84666 23.77
11 1000.0000 (d11)
12 80.3861 2.5949 1.95374 32.31
13 -61.7239 0.1500
14 28.8747 2.0551 2.00100 29.12
15 76.5246 1.7481
16 166.6079 0.8000 1.48749 70.41
17 17.4628 4.1322
18 (Aperture) ∞ 0.8540
19 30.0108 2.7674 1.43700 95.06
20 -395.6973 0.1500
21 17.5728 3.7649 1.43700 95.06
22 -65.4343 0.8000 1.92118 23.95
23 29.9433 1.8692
24 48.5854 2.1908 1.59282 68.60
25 -76.4819 0.6275
26 679.7559 0.8000 1.84666 23.77
27 22.7381 1.1944
28 149.1524 2.2243 1.80420 46.48
29 -49.9777 0.1500
30 21.0582 3.8827 1.43700 95.06
31 120.0000 0.1500
32 28.4961 3.3685 1.43700 95.06
33 ∞ 12.7099
34 ∞ 4.0000 1.51633 64.12
35 ∞ (BF)

[Aspherical data]
9 sides
K 0.0000
A4 -1.1788E-06
A6 -7.2708E-08
A8 6.1681E-10
A10 -2.5605E-12

[Various data]
INF 120mm
Focal length 7.90 7.60
F number 1.82 1.83
Full angle of view 2ω 197.08 197.08
Image height Y 11.60 11.71

[Variable interval data]
Shooting distance INF 120mm
d8 3.2000 10.2212
d11 10.3358 3.3146
BF 1.0000 1.0000

[Lens group data]
Group Start surface Focal length
G1 1 -8.93
G2 9 159.08
G3 12 23.60
G1N1 1 -12.40
G1P1 5 54.73
G1N2 7 -30.99
G3a 12 34.44
G3b 19 26.92

Reference Example 8

FIG. 36 is a lens configuration diagram of a fish-eye lens according to Reference Example 8 of the present invention. In order from the object side, the first lens group G1 has a negative refractive power, G2 has a positive refractive power, and a third lens group G3 has a positive refractive power. The first lens group G1 is convex on the object side. A positive meniscus lens having a negative refractive power, a negative meniscus lens L1N1 having a negative refractive power, a negative meniscus lens L2N1 having a convex surface facing the object side, and a positive meniscus lens having a convex surface facing the object side. A first P1 lens group G1P1 having a refractive power of 1 and a first N2 lens group G1N2 having a negative refractive power composed of a biconcave lens L3N2, and the second lens group G2 is a biconvex lens whose surface on the object side is aspherical. The third lens group G3 includes a biconvex lens, a positive meniscus lens having a convex surface facing the object side, and a convex meniscus having a convex surface facing the object side. A 3a lens group G3a composed of a cusp lens, an aperture stop S, a biconvex lens, a cemented lens composed of a biconvex lens and a biconcave lens, a biconvex lens whose surface on the object side is aspheric, and a convex surface facing the object side The third lens group G3b includes a negative meniscus lens, a biconvex lens, and a third convex lens group G3b. The first lens group G1 and the third lens group G3 are used when focusing from an infinite object to a close object. It is fixed with respect to the image plane, and the second lens group G2 moves to the image side.

  A filter F that is a plane-parallel plate is disposed between the third lens group G3 and the image plane. The position of the filter F on the optical axis does not affect the aberration anywhere between the third lens group G3 and the image plane.

Subsequently, specification values of the fisheye lens according to Example 8 are shown below.
Numerical example 8
Unit: mm
[Surface data]
Surface number rd nd vd
1 52.8269 2.0000 2.00100 29.12
2 16.0322 8.6375
3 29.6732 1.0000 1.77250 49.60
4 20.2235 0.0000
5 20.2235 3.5079 1.43700 95.06
6 23.2948 5.8864
7 -33.0406 0.8000 1.77250 49.60
8 62.4290 (d8)
9 * 78.4558 2.7605 1.80610 40.71
10 -76.8174 0.8000 1.84666 23.77
11 322.4303 (d11)
12 92.7714 3.0594 2.00100 29.12
13 -45.9457 0.1500
14 22.0682 2.3990 2.00100 29.12
15 53.0284 3.7683
16 347.9376 0.8000 1.74950 35.03
17 16.5674 3.3034
18 (Aperture) ∞ 2.0000
19 42.3885 1.9553 1.59282 68.60
20 -140.5558 0.1500
21 18.6643 3.4370 1.49700 81.58
22 -42.1334 0.8000 1.80518 25.45
23 23.9035 2.7283
24 * 27.5771 2.6061 1.59201 67.00
25 -316.8835 0.1500
26 318.5373 0.8000 1.84666 23.77
27 22.7889 0.8031
28 41.6877 3.4409 1.59282 68.60
29 -40.9352 0.1500
30 23.8577 4.6268 1.59282 68.60
31 -113.1889 12.6896
32 ∞ 4.0000 1.51633 64.12
33 ∞ (BF)

[Aspherical data]
9 faces 24 faces
K 0.0000 0.0000
A4 -1.3957E-06 -2.7217E-06
A6 -9.8869E-08 -2.3923E-07
A8 6.6342E-10 9.2238E-09
A10 -2.0259E-12 -7.8119E-11

[Various data]
INF 118mm
Focal length 7.89 7.71
F number 1.82 1.83
Full angle of view 2ω 197.32 197.32
Image height Y 11.60 11.87

[Variable interval data]
Shooting distance INF 118mm
d8 4.0548 10.3901
d11 9.7353 3.4000
BF 1.0000 1.0000

[Lens group data]
Group Start surface Focal length
G1 1 -8.36
G2 9 139.25
G3 12 25.89
G1N1 1 -17.00
G1P1 5 260.52
G1N2 7 -27.87
G3a 12 30.63
G3b 19 22.16

  The most object-side surface of the lens in the first P1 lens group G1P1 may be a cemented lens when sufficiently close to the image-side surface of the lens in the first N1 lens group G1N1. Alternatively, the most image side surface of the lens in the first P1 lens group G1P1 may be a cemented lens when it is sufficiently close to the most object side surface of the lens in the first N2 lens group G1N2.

  In addition, a list of corresponding values of the conditional expressions in each of these examples is shown.

[Values for conditional expressions]
EX1 EX2 EX3 EX4
(1) 0.10 <(L1N1R1-L1N1R2) / (L1N1R1 + L1N1R2) <1.00 0.49 0.51 0.65 0.55
(2) 0.10 <(L2N1R1-L2N1R2) / (L2N1R1 + L2N1R2) <1.00 0.13 0.56 0.30 0.30
(3) 0.15 <L3N2R1 / fL3N2 <4.00 1.70 0.31 0.52 1.99
(4) 8.0 <f2 / f <45.0 23.00 13.00 15.85 16.04
(5) 4.00 <f1P1 / f <70.00----
(6) -2.40 <f1 / f <-0.70 -1.03 -1.06 -1.20 -1.08
(7) -5.00 <fN12 / f <-1.00 -2.49 -1.40 -1.80 -2.47
(8) 2.80 <EXP / f <20.00 5.80 5.77 6.45 5.77
(9) 0.05 <D13 / LT <0.45 0.20 0.14 0.20 0.23
(10) 1.40 <f3 / f <6.50 3.09 3.16 2.87 3.11
(11) 0.05 <D2S / LT <0.60 0.25 0.26 0.21 0.28
(12) 1.30 <f3a / f <12.50 3.10 3.75 6.33 2.65
(13) 1.40 <f3b / f <10.00 4.26 3.26 3.33 4.80

EX5 EX6 EX7 EX8
(1) 0.10 <(L1N1R1-L1N1R2) / (L1N1R1 + L1N1R2) <1.00 0.53 0.53 0.50 0.53
(2) 0.10 <(L2N1R1-L2N1R2) / (L2N1R1 + L2N1R2) <1.00 0.19 0.71 0.70 0.19
(3) 0.15 <L3N2R1 / fL3N2 <4.00 1.19 1.43 0.76 1.19
(4) 8.0 <f2 / f <45.0 17.63 15.39 20.14 17.64
(5) 4.00 <f1P1 / f <70.00 32.98 6.00 6.93 33.00
(6) -2.40 <f1 / f <-0.70 -1.06 -1.09 -1.13 -1.06
(7) -5.00 <fN12 / f <-1.00 -2.15 -1.69 -1.57 -2.15
(8) 2.80 <EXP / f <20.00 6.46 7.10 5.78 6.46
(9) 0.05 <D13 / LT <0.45 0.18 0.19 0.17 0.18
(10) 1.40 <f3 / f <6.50 3.28 3.05 2.99 3.28
(11) 0.05 <D2S / LT <0.60 0.25 0.23 0.23 0.25
(12) 1.30 <f3a / f <12.50 3.88 4.11 4.36 3.88
(13) 1.40 <f3b / f <10.00 2.81 3.30 3.41 2.81

S: aperture stop I: image plane F: filter G1: first lens group G2: second lens group G3: third lens group G1N1: first N1 lens group G1P1: first P1 lens group G1N2: first N2 lens group G3a: first 3a lens group G3b: 3b lens group C: C line (wavelength λ = 656.3 nm)
d: d line (wavelength λ = 587.6 nm)
g: g line (wavelength λ = 435.8 nm)
Y: image height ΔS: sagittal image plane ΔM: meridional image plane

Claims (5)

In order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a positive refractive power,
The first lens group G1 includes, in order from the object side, a first N1 lens group G1N1 having a negative refractive power and a first N2 lens group G1N2 having a negative refractive power.
The first N1 lens group G1N1 includes a first negative meniscus lens L1N1 that is convex toward the object side in order from the object side, and a second negative meniscus lens L2N1 that is convex toward the object side. The first N2 lens group G1N2 is located on the object side. Having negative lens L3N2 with concave facing,
The third lens group G3 includes, in order from the object side, a 3a lens group G3a, an aperture stop S, and a 3b lens group G3b.
When focusing from an object at infinity to an object at a short distance, the first lens group G1 and the third lens group G3 are fixed with respect to the image plane, and the second lens group G2 moves to the image side. And
A fish-eye lens satisfying the following conditional expression:
The fish-eye lens of the present invention is an optical system in which the distortion at the half angle of view ω = 90 ° is −100% in the central projection method, and the principal ray for calculating the distortion is the center of the aperture stop S. Is defined as a ray passing through.
(1) 0.10 <(L1N1R1-L1N1R2) / (L1N1R1 + L1N1R2) <1.00
(2) 0.10 <(L2N1R1-L2N1R2) / (L2N1R1 + L2N1R2) <1.00
(3) 0.15 <L3N2R1 / fL3N2 <4.00
(4) 8.0 <f2 / f <45.0
(8) 2.80 <EXP / f <20.00
(11) 0.05 <D2S / LT <0.60
(12) 1.30 <f3a / f <12.50
(13) 1.40 <f3b / f <10.00
L1N1R1: Object-side radius of curvature L1N1R2 of the first negative meniscus lens L1N1: Image-side radius of curvature L2N1R1 of the first negative meniscus lens L1N1: Object-side radius of curvature L2N1R2 of the second negative meniscus lens L2N1: Second negative meniscus lens Image side radius of curvature L3N2R1 of L2N1: Object side radius of curvature fL3N2 of the negative lens L3N2: Focal length f of the negative lens L3N2: Focal length f2 of the entire system at infinity shooting: Focal length EXP of the second lens group G2 : Distance from exit pupil position to image plane when focusing on infinity
D2S: Distance from the final surface of the second lens group G2 to the aperture stop S when focusing on infinity
LT: distance from the top surface of the first lens group G1 to the image plane
f3a: focal length of the third-a lens group G3a
f3b: Focal length of the third b lens group G3a The first lens group G1 includes, in order from the object side, the first N1 lens group G1N1 having negative refractive power, the first P1 lens group G1P1 having positive refractive power, and the first N2 lens group G1N2 having negative refractive power. And
The fisheye lens according to claim 1, wherein the following condition is satisfied.
(5) 4.00 <f1P1 / f <70.00
f: focal length of the entire system at infinity shooting f1P1: focal length of the first P1 lens group G1P1 The fisheye lens according to claim 1 or 2, wherein the following condition is satisfied.
(6) -2.40 <f1 / f <-0.70
(7) -5.00 <fN12 / f <-1.00
(9) 0.05 <D13 / LT <0.45
(10) 1.40 <f3 / f <6.50
f: focal length of the entire system at infinity shooting f1: focal length of the first lens group G1 fN12: composite focal length D13 from the first negative meniscus lens L1N1 to the second negative meniscus lens L2N1: the first Distance LT from the last surface of the lens group G1 to the leading surface of the third lens group G3: Distance from the leading surface of the first lens group G1 to the image plane f3: Focal length of the third lens group G3 Fisheye lens as claimed in any one of claims 1 to 3, characterized in that have a non-spherical surface to said second lens group G2. The third lens group G3 includes a 3a lens group G3a, an aperture stop S, and a 3b lens group G3b in order from the object side. The 3b lens group G3b is a d-line (wavelength λ = 587. fisheye lens according to any one of claims 1 to 4 the Abbe number with respect to 56 nm) is characterized by closed two or more lenses having greater than 60 positive refractive power.

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