JP2018072638A - Imaging lens, imaging apparatus, and manufacturing method of imaging lens - Google Patents

Abstract

An object of the present invention is to provide an imaging lens having a wide angle of view and a small (bright) F-number while having a simple configuration. SOLUTION: An imaging lens PL for forming an image of an object on a curved imaging surface with a concave surface facing the object side is arranged in order from the object side and includes a first lens group G1 having a negative refractive power and a positive lens group G1. and a third lens group G3 having a positive refractive power. The first lens group G1 has one or more positive lenses and one or more negative lenses, and the second lens group G2 has two or more positive lenses, one or more negative lenses and an aperture stop. The third lens group G3 has one or more positive lenses and one or more negative lenses, and satisfies the following conditional expression. 0.03<F12/F3<0.30 where F12: the combined focal length of the first lens group and the second lens group at infinity, F3: the focal length of the third lens group. [Selection drawing] Fig. 1

Description

  The present invention relates to an imaging lens, an imaging apparatus using the imaging lens, and a manufacturing method of the imaging lens.

  In recent years, an imaging lens has been devised that uses an imaging element having an imaging surface curved with a concave surface facing the object side, and forms an image of the object on the curved imaging surface (see, for example, Patent Document 1). In this imaging lens, since it is necessary to reduce the radius of curvature of the imaging surface, it is difficult to manufacture the imaging element. Therefore, an imaging lens having a relatively small imaging surface curvature is required. Furthermore, there is a demand for an imaging lens having a simple configuration and a wide angle of view and a small F number (bright).

JP2013-25202A

The imaging lens according to the first aspect of the present invention is an imaging lens that forms an image of an object on an imaging surface curved with a concave surface facing the object side, and has negative refractive power arranged in order from the object side. A first lens group having a positive refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. The first lens group has one or more positive lenses and one or more negative lenses, and the second lens group has two or more positive lenses, one or more negative lenses, and an aperture stop. The third lens group has one or more positive lenses and one or more negative lenses, and satisfies the following conditional expression.
0.03 <F12 / F3 <0.30
F12: the combined focal length of the first lens group and the second lens group at infinity,
F3: focal length of the third lens group.

  An imaging apparatus according to the second aspect of the present invention includes the above-described imaging lens that forms an image of an object on an imaging surface curved with a concave surface facing the object side, and the image formed on the imaging surface. And an image pickup device for picking up an image of an object.

An imaging lens manufacturing method according to a third aspect of the present invention is an imaging lens manufacturing method for forming an image of an object on an imaging surface curved with a concave surface facing the object side. Arranging a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, arranged in order from the object side, In the step, the first lens group includes one or more positive lenses and one or more negative lenses, and the second lens group includes two or more positive lenses, one or more negative lenses, and an aperture. The third lens group has a stop, and has at least one positive lens and at least one negative lens, and each lens is arranged in a lens barrel so as to satisfy the following conditional expression.
0.03 <F12 / F3 <0.30
F12: the combined focal length of the first lens group and the second lens group at infinity,
F3: focal length of the third lens group.

It is a lens block diagram of the imaging lens which concerns on 1st Example. (A) is various aberration diagrams in the infinite focus state of the imaging lens according to the first example, and (b) is various aberration diagrams in the short distance focus state. It is a lens block diagram of the imaging lens which concerns on 2nd Example. (A) is various aberration diagrams in the infinite focus state of the imaging lens according to the second example, and (b) is various aberration diagrams in the short distance focus state. It is a lens block diagram of the imaging lens which concerns on 3rd Example. (A) is various aberration diagrams in the infinite focus state of the imaging lens according to the third example, and (b) is various aberration diagrams in the short distance focus state. It is a lens block diagram of the imaging lens which concerns on 4th Example. (A) is various aberration diagrams in the infinite focus state of the imaging lens according to the fourth example, and (b) is various aberration diagrams in the short distance focus state. It is sectional drawing of the digital still camera provided with the imaging lens which concerns on this embodiment. It is a flowchart which shows the schematic step of the manufacturing method of the imaging lens which concerns on this embodiment.

  Hereinafter, the present embodiment will be described with reference to the drawings. FIG. 9 shows a schematic configuration (cross-sectional view) of a digital still camera CAM as an imaging apparatus including the imaging lens PL according to the present embodiment. In this specification, the term “lens component” is sometimes used. In this case, the lens component is used as a term meaning both “single lens and cemented lens”.

  The digital still camera CAM includes an imaging lens PL (for example, the imaging lens PL (1) of the first embodiment) along the optical axis and a curved imaging surface Ci that is concave on the object side in the camera housing 10. An image sensor C having In this camera CAM, when a power button (not shown) is pressed, a shutter (not shown) provided on the imaging lens PL is opened, and light from the subject (object) is condensed by the imaging lens PL. A subject image is formed on the imaging surface Ci. At this time, the imaging lens PL is configured such that the image plane I of the subject image formed by the imaging lens PL has the same concave shape as the imaging plane Ci. The image sensor C acquires a subject image formed on the imaging surface Ci, and the subject image is displayed on the liquid crystal monitor M disposed behind the imaging lens PL. When the photographer decides the composition of the subject image while looking at the liquid crystal monitor M and presses the release button B1, the subject image acquired by the image sensor C at that time is recorded and saved in a memory (not shown), and photographing is performed. .

  The image sensor C is configured using an image sensor such as a CCD or a CMOS. The imaging surface Ci of the imaging device C is formed by two-dimensionally arranging pixels (photoelectric converters) constituting the image sensor, and the imaging surface Ci has a concave surface facing the object side (for example, Curved (spherically). The center point of the spherical surface of the imaging surface Ci is arranged so as to be located on the optical axis of the imaging lens PL. The digital still camera CAM has various functional members such as an auxiliary light emitting unit, function buttons used for setting conditions, and the like. However, these are already well known, and both illustration and description are omitted. . The camera CAM may be a mirrorless camera or a single-lens reflex type camera having a quick return mirror.

  As described above, the imaging lens PL according to the present embodiment is configured to form a subject image on the imaging surface Ci with the concave surface facing the object side. For example, the imaging lens PL (1) shown in 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, arranged in order from the side. . The imaging lens PL according to the present embodiment may be the imaging lens PL (2) shown in FIG. 3, the imaging lens PL (3) shown in FIG. 5, or the imaging lens PL (4) shown in FIG. .

In the imaging lens PL of the present embodiment, as described above, the imaging element in which the image plane I of the subject formed by the imaging lens PL is curved with the concave surface facing the object side, and is similarly curved with the concave surface facing the object side. A subject image is formed on the C imaging surface Ci. As a result, it is possible to correct the astigmatism prior to the curvature of field in the minus direction of the meridional image plane (the direction from the image side to the object side), and to obtain good imaging performance. . In addition, since the priority for correcting the field curvature in the negative direction of the meridional image plane is low, it is not necessary to reduce the Petzval sum. Therefore, an optical material having a high refractive index can be used for the positive lens in the most object side lens group that functions as a wide-angle converter (the positive lens used in the first lens group G1).

  In such correction of the aberration of the imaging lens PL, a lens having a minimum configuration capable of correcting Seidel's five aberrations is a triplet type lens. This triplet type lens can be used as a master lens (for example, the second lens group G2), and a wide angle converter composed of a negative lens and a positive lens can be arranged on the object side of the master lens to widen the angle of view. It is. The structure of the wide-angle converter arranged on the object side of the master lens is mainly configured to correct aberrations associated with widening the angle of view, so that a doublet-type lens is used as a master lens instead of a triplet-type lens. It is also possible.

  Here, in order to further widen the angle, a rear group (for example, having a positive lens component and a negative lens component on the image plane side of the master lens, in which the negative refracting power of the wide angle converter is strengthened and the image surface side of the master lens is configured. It is preferable to add the third lens group G3). The reason is that negative distortion and field curvature due to the refracting power of the wide-angle converter can be corrected by the rear group (third lens group G3).

  At this time, if the imaging performance is given the highest priority as an optical system with a bright Fno, it is preferable that the rear group (third lens group G3) has a positive refractive power. This is because the refractive power of the master lens (second lens group G2) and the rear group (third lens group G3) can be used weakly, and the spherical aberration correction at each lens becomes easy.

  In view of the above, the imaging lens of the present embodiment is configured, and the specific lens configuration will be described below. The imaging lens according to the present embodiment is an imaging lens that forms an image of an object on an imaging surface curved with a concave surface facing the object side, and is a first lens having negative refractive power arranged in order from the object side. It is configured to include a group G1, 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 one or more positive lenses and one or more negative lenses, and the second lens group G2 includes two or more positive lenses, one or more negative lenses, and an aperture. The third lens group G3 has a stop, and has one or more positive lenses and one or more negative lenses, and further satisfies the following conditional expression (1).

0.03 <F12 / F3 <0.30 (1)
F12: a combined focal length at infinity of the first lens group G1 and the second lens group G2,
F3: focal length of the third lens group G3.

  By configuring the imaging lens so as to satisfy the conditional expression (1) having the above-described configuration, it is a simple configuration, but has a wide angle of view, a small F number (bright), and a relatively curved imaging surface. A small imaging lens can be obtained.

If the lower limit of conditional expression (1) is not reached, it will be difficult to reduce (brighten) Fno. On the other hand, if the upper limit value of conditional expression (1) is exceeded, the field curvature in the direction opposite to the concave shape of the image sensor (convex surface direction, image surface direction, image side relative to the concave surface of the image sensor) becomes excessive. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.05. Similarly, the upper limit value of conditional expression (1) is preferably 0.20. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.07. Similarly, the upper limit value of conditional expression (1) is preferably 0.10.

The imaging lens according to the present embodiment preferably further satisfies the following conditional expression (2).
0.05 <F2 / F3 <0.40 (2)
F2: focal length of the second lens group G2.

  Conditional expression (2) indicates a preferable condition for improving the performance of the imaging lens according to the present embodiment. If the lower limit of conditional expression (2) is not reached, the short distance fluctuation of coma aberration becomes large, which is not preferable. On the other hand, when the value exceeds the upper limit value of the conditional expression (2), the reverse field curvature with respect to the concave shape of the image sensor becomes excessive, which is not preferable. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.10. Similarly, the upper limit value of conditional expression (2) is preferably set to 0.30. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.15. Similarly, the upper limit value of conditional expression (2) is preferably 0.20.

The imaging lens according to the present embodiment preferably further satisfies the following conditional expression (3).
-10.00 <F1 / F3 <-0.10 (3)
F1: A focal length of the first lens group G1.

  Conditional expression (3) also shows a preferable condition for improving the performance of the imaging lens according to the present embodiment. If the lower limit of conditional expression (3) is not reached, the short distance fluctuation of coma aberration becomes large, which is not preferable. If the upper limit of conditional expression (3) is exceeded, the reverse field curvature with respect to the concave shape of the image sensor becomes excessive, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to −8.50. Similarly, it is preferable that the upper limit value of conditional expression (3) is −0.30. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit value of conditional expression (3) to −7.00. Similarly, the upper limit value of conditional expression (3) is preferably −0.50.

The imaging lens according to the present embodiment preferably further satisfies the following conditional expression (4).
−3.00 <F3 / G3bR2 <7.00 (4)
G3bR2: radius of curvature of the image side surface of the final negative lens arranged closest to the image plane among the negative lenses included in the third lens group G3.

  Conditional expression (4) also shows a preferable condition for improving the performance of the imaging lens according to the present embodiment. If the lower limit of conditional expression (4) is not reached, the reverse field curvature with respect to the concave shape of the image sensor becomes excessive, which is not preferable. Exceeding the upper limit value of conditional expression (4) is not preferable because the short-distance fluctuation of the coma aberration of the upper ray increases. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to −2.00. Similarly, the upper limit of conditional expression (4) is preferably 6.00. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to −1.00. Similarly, the upper limit value of conditional expression (4) is preferably set to 5.00.

The imaging lens according to the present embodiment preferably further satisfies the following conditional expression (5).
-5.00 <G3aR2 / G3bR1 <1.50 (5)
However, G3bR1: the radius of curvature of the object side surface of the final negative lens arranged closest to the image plane among the negative lenses included in the third lens group G3,
G3aR2: the radius of curvature of the image-side surface of the lens disposed at the position facing the object side of the final negative lens.

  Conditional expression (5) also shows a preferable condition for improving the performance of the imaging lens according to the present embodiment. If the lower limit of conditional expression (5) is not reached, the flare becomes large, which is not preferable. If the upper limit of conditional expression (5) is exceeded, the reverse field curvature with respect to the concave shape of the image sensor becomes excessive, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit value of conditional expression (5) to −4.00. Similarly, the upper limit of conditional expression (5) is preferably set to 1.10. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to −3.00. Similarly, the upper limit value of conditional expression (5) is preferably 0.70.

The imaging lens according to the present embodiment preferably further satisfies the following conditional expression (6).
−0.50 <F23 / F1 <−0.01 (6)
F23: a combined focal length at infinity of the second lens group G2 and the third lens group G3.

  Conditional expression (6) also shows a preferable condition for improving the performance of the imaging lens according to the present embodiment, specifically, a condition regarding the first lens group (wide-angle converter). If the lower limit of conditional expression (6) is not reached, the reverse field curvature with respect to the concave shape of the image sensor becomes excessive, which is not preferable. If the upper limit of conditional expression (6) is exceeded, it is necessary to reduce the radius of curvature of the concave surface of the image sensor in order to correct the field curvature (the curvature (radius) of the field curvature becomes tight (small). Accordingly, the curvature (radius) of the concave surface of the image sensor is also not preferable. Furthermore, the astigmatic difference increases, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (6) to −0.40. Similarly, it is preferable that the upper limit value of the conditional expression (6) is −0.02. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit value of conditional expression (6) to −0.30. Similarly, the upper limit value of conditional expression (6) is preferably set to −0.03.

  In the imaging lens according to the present embodiment, it is preferable that the first lens group G1 has a negative lens closest to the object side. The second lens group G2 preferably has a positive lens closest to the object side and a positive lens closest to the image plane. Furthermore, it is preferable that the third lens group G3 has a negative lens on the most image side. Thereby, the structure of each lens group or the boundary of each lens group becomes clear.

The imaging lens according to the present embodiment preferably further satisfies the following conditional expression (7).
−0.40 <F2 / Ri <−0.05 (7)
Ri: the radius of curvature of the imaging surface curved with the concave surface facing the object side.

  Conditional expression (7) also shows a preferable condition for improving the performance of the imaging lens according to the present embodiment, specifically, a condition related to the second lens group G2 (master lens). If the lower limit of conditional expression (7) is not reached, it is not preferable because it is necessary to reduce the radius of curvature of the concave surface of the image pickup device for field curvature correction. Furthermore, the astigmatic difference becomes large, which is not preferable. If the upper limit value of conditional expression (7) is exceeded, the concave shape and the reverse field curvature of the image sensor become excessive, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (7) to −0.30. Similarly, the upper limit of conditional expression (7) is preferably set to −0.10. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (7) to −0.20. Similarly, the upper limit value of conditional expression (7) is preferably set to −0.15.

In the imaging lens according to the present embodiment, the first lens group G1, the second lens group G2, and the third lens group G3 can move the first lens group that moves in the optical axis direction during focusing or the The third lens group is a first focusing group, the second lens group that moves in the optical axis direction independently of the first focusing group is a second focusing group, and the following conditional expression (8) It is preferable to satisfy.
0.60 <X1 / X2 <1.10 (8)
Where X1: the amount of movement of the first focusing group when focusing from an object at infinity to a near object,
X2: The amount of movement of the second focusing group when focusing from an object at infinity to a near object.

  By adopting the first and second focusing group configurations that move along different trajectories at the time of focusing as described above, it is possible to reduce the close variation in negative field curvature aberration. Conditional expression (8) also shows a preferable condition for improving the performance of the imaging lens according to the present embodiment. If the lower limit of conditional expression (8) is not reached, field curvature correction becomes excessive, which is not preferable. If the upper limit value of conditional expression (8) is exceeded, field curvature correction becomes insufficient, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (8) to 0.70. Similarly, the upper limit value of conditional expression (8) is preferably 1.05. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (8) to 0.80. Similarly, the upper limit value of conditional expression (8) is preferably set to 1.00.

  Here, as can be seen from examples described later, the first focusing group includes a configuration including the first lens group G1 and a configuration including the third lens group G3, but is not limited thereto. For example, the first focusing group may be composed of a part of the lenses of the first lens group G1, and may be composed of a part of the lenses of the third lens group G3.

  Further, the second focusing group includes a configuration including the second lens group G2 and the first lens group G1, and a configuration including the second lens group G2 and the third lens group G3. Absent. The second focusing group may be constituted by a part of the first lens group G1 and the second lens group G2, or may be constituted by a part of the second lens group G2 and the third lens group G3.

  In the imaging lens according to the present embodiment, it is preferable that a field stop is disposed in the first lens group G1 in order to cut the flare of the lower light beam with a large aperture ratio.

  In the imaging lens according to this embodiment, in each of the first, second, and third lens groups, it is preferable that at least one surface has an aspherical shape. Thereby, an imaging lens can be configured with a small number of lenses.

  The imaging apparatus according to the present embodiment includes the above-described imaging lens that forms an image of an object on a curved surface with a concave surface facing the object side, as represented by the digital still camera CAM shown in FIG. 9 described above. A curved surface as an imaging surface, and an imaging device that captures an image of the object formed on the imaging surface. With such a configuration, it is possible to obtain an imaging apparatus having a simple configuration but a wide angle of view, a small F-number (bright), and a relatively small curvature of the imaging surface.

  In the image pickup apparatus according to the present embodiment, it is preferable that a light splitting optical element is not provided between the image pickup lens and the image pickup element. When a light splitting optical element (so-called OLPF) is arranged on the object side of an image sensor that is concave on the object side, it is necessary to align it with the shape of the image sensor, and this also has a concave shape. This is because it is difficult to deform because it is made of a crystalline material. Moreover, although it can be made into a concave shape by CG processing or the like, there is a problem that desired optical characteristics cannot be obtained. An infrared cut filter may be arranged.

In the imaging apparatus of the present embodiment, if the rotational symmetry axis formed by the concave shape of the imaging element and the optical axis of the optical system are shifted, the image quality becomes non-uniform in the diagonal direction of the screen. It is necessary to align. For this reason, in the image pickup apparatus according to the present embodiment, it is preferable that the image pickup lens and the image pickup element are integrally configured so that the axis of rotation symmetry and the optical axis can be adjusted.

  Next, a method for manufacturing the imaging lens PL described above will be outlined with reference to FIG. First, a first lens group G1 having negative refracting power, a second lens group G2 having positive refracting power, and a third lens group having positive refracting power are arranged in order from the object side in the lens barrel. G3 is arranged (step ST1). At this time, the first lens group G1 includes one or more positive lenses and one or more negative lenses, and the second lens group G2 includes two or more positive lenses, one or more negative lenses, and an aperture stop. The third lens group G3 is disposed so as to have one or more positive lenses and one or more negative lenses (step ST2). At this time, the respective lenses are arranged in the lens barrel so as to satisfy at least the conditional expression (1) (step ST3).

  Hereinafter, each example of the present embodiment will be described with reference to the accompanying drawings. 1, FIG. 3, FIG. 5 and FIG. 7 show the lens configuration and refractive power distribution of the imaging lenses PL {PL (1) to PL (4)} according to the first to fourth embodiments. The sign (+) or (-) attached to the symbol of each lens group indicates the refractive power of each lens group. Further, the movement directions when the first to third lens groups G1 to G3 are focused from an infinitely distant object to a very close object (finite distance object) as a focusing lens group are “focus X1” and “focus X2”. ”And an arrow.

  In FIG. 1, FIG. 3, FIG. 5, and FIG. 7, each lens group is represented by a combination of symbol G and a number, and each lens is represented by a combination of symbol L and a number. In this case, in order to prevent complications due to an increase in the types and numbers of codes and numbers, the lens groups and the like are represented using combinations of codes and numbers independently for each embodiment. For this reason, even if the combination of the same code | symbol and number is used between Examples, it does not mean that it is the same structure.

  Tables 1 to 4 are shown below. Of these, Table 1 is the first example, Table 2 is the second example, Table 3 is the third example, and Table 4 is the values in the fourth example. It is a table | surface which shows. In each embodiment, the calculation target of aberration characteristics is d-line (wavelength λ = 587.6 nm), g-line (wavelength λ = 435.8 nm), C-line (wavelength λ = 656.3 nm), F-line (wavelength λ = 486.1 nm).

  In [Specification Data] in each table, f is the focal length of the imaging lens PL, FNO is the F number, ω is the maximum shooting half angle of view (unit is “°”), and φ1 is the inner diameter of the field stop FS. , Φ2 indicate the inner diameter of the aperture stop AS. In [Lens data], the surface number is the number of each lens surface counted from the object side, R is the radius of curvature of each lens surface, D is the distance between the lens surfaces, and νd is the d-line (wavelength λ = 587. Abbe number with respect to 6 nm), and nd represents the refractive index with respect to d-line (wavelength λ = 587.6 nm). In [Lens Data], Dm (m: lens surface number) represents the distance between the variable surfaces, and Bf represents the back focus. In addition, * mark attached | subjected to the left of the 1st column (surface number) shows that the lens surface is an aspherical surface. Further, the curvature radius “∞” indicates a plane or an opening, and the description of the refractive index nd of air = 1.000000 is omitted.

The aspheric coefficient shown in [Aspherical data] is that the height (ring zone position) in the direction perpendicular to the optical axis is y, the sag amount in the optical axis direction is X (y), and the radius of curvature of the reference spherical surface (near) When the radius of curvature (axis curvature) is r, the conic constant is κ, and the n-th order (n = 2, 4, 6, 8) aspheric coefficient is An, it is expressed by the following equation (A). In [Aspherical data], “En” indicates “× 10 ⁻ⁿ ”. For example, “1.234E-05” indicates “1.234 × 10 ⁻⁵ ”.

X (y) = (y ² / r) / {1+ (1−κ × y ² / r ² ) ^1/2 }
+ A2 × y ² + A4 × y ⁴ + A6 × y ⁶ + A8 × y ⁸ (A)

  In [variable interval data], f indicates the focal length of the imaging lens PL, and β indicates the imaging magnification. The [variable interval data] includes the value of the distance D0 from the object to the first lens surface, the value of the variable surface interval Dm, the value of the back focus Bf, the total length, and the total length corresponding to each focal length and imaging magnification. TL value. [Lens Group Data] indicates focal lengths of the first lens group G1, the second lens group G2, the third lens group G3, the front lens group Gf, and the rear lens group Gr. [Conditional Expression Corresponding Value] indicates the corresponding value of each conditional expression.

  The focal length f, the radius of curvature R, and other length units listed in all the following specifications are generally “mm”, but the optical system may be proportionally enlarged or reduced. Since equivalent optical performance can be obtained, the present invention is not limited to this. The explanation of the table so far is common to all the embodiments, and the duplicate explanation below will be omitted.

(First embodiment)
First, the first embodiment will be described with reference to FIGS. FIG. 1 is a lens configuration diagram of the imaging lens PL (1) according to the first example in an infinitely focused state. The imaging lens PL (1) includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a positive refraction arranged in order from the object side along the optical axis. And a third lens group G3 having power. The imaging lens PL (1) is a single focus lens, and the diagonal length from the center of the imaging device C corresponding to the imaging lens PL (1) to the diagonal (that is, the maximum image height on the imaging plane Ci) IH is 7. .77 mm. Further, the radius of curvature Rc of the imaging surface Ci of the imaging element C curved in a spherical shape so that the concave surface is directed toward the object side is −68 mm with the value in the direction in which the concave surface is directed toward the image surface I being a positive value.

  The first lens group G1 is composed of a negative meniscus lens L1 having a convex surface facing the object side, a positive meniscus lens L2 having a convex surface facing the object side, and a field stop FS. Note that the image side surface of the negative meniscus lens L1 is an aspherical surface. The second lens group G2 includes a biconvex positive lens L3, an aperture stop AS, a biconcave negative lens L4, and a biconvex positive lens L5. The image side surface of the negative lens L4 is an aspherical surface. The third lens group G3 includes a cemented positive lens including a biconvex positive lens L6 and a negative meniscus lens L7 having a concave surface directed toward the object side. The image side surface of the negative meniscus lens L7 is an aspherical surface.

In the imaging lens PL (1), focusing from an infinite distance to a close object (finite distance object) is performed while reducing the distance between the first lens group G1 and the second lens group G2. The third lens group G1 to G3 is moved in the optical axis direction. During focusing, the first lens group G1 moves integrally as the first focusing group, the second lens group G2 and the third lens group G3 move integrally as the second focusing group, and the field stop FS is The aperture stop AS moves integrally with the second lens group G2 integrally with the first lens group G1. For this reason, for example, in the case of the first embodiment, the surface intervals D5 and D12 change according to the in-focus state, and the values are shown in the table of [Variable interval data]. The surface interval D0 in this table is the distance from the object to the first surface. This description is the same for the remaining embodiments.

  Table 1 below shows each item in the first embodiment.

(Table 1)
[Specification data]
f = 7.4
FNO = 2.0
ω = 53.5 °
[Lens data]
Surface number R D νd nd
1) 594.3330 1.4000 53.22 1.693500
* 2) 5.3763 6.8500
3) 11.7788 1.9000 37.38 1.900430
4) 94.1583 1.0000
5) ∞ D5 Field stop FS (φ1 = 7.31)
6) 11.3036 1.9000 52.34 1.755000
7) -142.6369 0.2000
8) ∞ 0.5000 Aperture stop AS (φ2 = 6.70)
9) -28.7250 4.1000 20.88 1.922860
* 10) 30.2636 0.4000
11) 43.5418 2.0000 81.61 1.497000
12) -10.8975 D12
13) 25.8648 2.0000 81.61 1.497000
14) -19.1211 1.1000 19.32 2.001780
* 15) -40.4099 Bf
[Aspherical data]
K A2 A4 A6 A8
Second side -0.0796 0.00000E + 00 3.80820E-04 1.44260E-06 0.00000E + 00
10th surface -2.9736 0.00000E + 00 4.77050E-04 5.25000E-06 0.00000E + 00
15th 0.6162 0.00000E + 00 1.72960E-04 0.00000E + 00 0.00000E + 00
[Variable interval data]
Infinite focusing state Short focusing state f, β 7.39999 -0.10000
D0 ∞ 71.529
D5 1.00000 0.92600
D12 1.00000 1.00000
Bf 7.62720 8.36729
TL 32.97720 33.64328
[Lens group data]
Lens group focal length G1 -448.504
G2 16.091
G3 56.380
[Conditional expression values]
(1) F12 / F3 = 0.156
(2) F2 / F3 = 0.285
(3) F1 / F3 = −7.955
(4) F3 / G3bR2 = −1.395
(5) G3aR2 / G3bR1 = 1.000
(6) F23 / F1 = −0.030
(7) F2 / Ri = −0.237
(8) X1 / X2 = 0.900

  Thus, in this embodiment, it can be seen that all the conditional expressions (1) to (8) are satisfied.

  FIG. 2 is a diagram illustrating various aberrations of the imaging lens PL (1) according to the first example. FIG. 2A is a diagram showing various aberrations when the imaging lens PL (1) is in focus at infinity, and FIG. 2B is a short distance focusing state (closest shooting distance L = 105 mm) of the imaging lens PL (1). FIG. In each aberration diagram, FNO represents the F number, A represents the maximum shooting half field angle in the negative direction, NA represents the numerical aperture, and H0 represents the object height. In each aberration diagram, d is a d-line (λ = 587.6 nm), g is a g-line (λ = 435.8 nm), C is a C-line (wavelength λ = 656.3 nm), and F is an F-line (wavelength). Aberration at λ = 486.1 nm) is shown. In the aberration diagram showing astigmatism, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. An aberration diagram showing lateral chromatic aberration is shown with reference to the d-line. The explanation of these aberration diagrams is the same in the other examples.

  From the respective aberration diagrams, it can be seen that in the first example, various aberrations are corrected well and the imaging performance is excellent. As a result, excellent optical performance can be ensured even in an imaging apparatus (for example, the digital still camera CAM shown in FIG. 9) equipped with the imaging lens PL (1) of the first embodiment.

(Second embodiment)
FIG. 3 is a lens configuration diagram of the imaging lens PL (2) according to the second example in the infinitely focused state. The imaging lens PL (2) includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a positive refraction arranged in order from the object side along the optical axis. And a third lens group G3 having power. The imaging lens PL (2) is a single focus lens, and the diagonal length from the center of the imaging element C corresponding to the imaging lens PL (2) to the diagonal (that is, the maximum image height on the imaging surface Ci) IH is 20 .8 mm. Further, the radius of curvature Rc of the imaging surface Ci of the imaging element C curved in a spherical shape so that the concave surface is directed toward the object side is −180 mm, where the value in the direction in which the concave surface is directed toward the image surface I is a positive value.

  The first lens group G1 includes a negative meniscus lens L1 having a convex surface facing the object side, a cemented positive lens of a biconvex positive lens L2 and a negative meniscus lens L3 having a concave surface facing the object side. Note that the image side surface of the negative meniscus lens L1 is an aspherical surface. The second lens group G2 includes a positive meniscus lens L4 having a convex surface facing the object side, an aperture stop AS, a negative meniscus lens L5 having a concave surface facing the object side, and a biconvex positive lens L6. The image side surface of the negative meniscus lens L5 is aspheric. The third lens group G3 includes a biconvex positive lens L7 and a negative meniscus lens L8 having a convex surface directed toward the object side. The object side surface of the negative meniscus lens L8 is an aspherical surface.

  In the imaging lens PL (2), focusing from an infinite distance to an object at a close distance (a finite distance object) is performed while increasing the distance between the second lens group G2 and the third lens group G3. The three lens groups G1 to G3 are moved in the optical axis direction. During focusing, the first lens group G1 and the second lens group G2 move integrally as a second focusing group, the third lens group G3 moves integrally as a first focusing group, and the aperture stop AS is It moves integrally with the second lens group G2.

  Table 2 below shows each item in the second embodiment.

(Table 2)
[Specification data]
f = 20.0
FNO = 2.0
ω = 53.1 °
[Lens data]
Surface number R D νd nd
1) 364.1942 3.8000 63.86 1.618810
* 2) 13.1737 19.0000
3) 22.3569 6.0000 58.96 1.518230
4) -157.4941 1.0000 29.14 2.001000
5) -571.5011 D5
6) 35.7290 3.5000 52.34 1.755000
7) 7209.3570 5.5000
8) ∞ 1.4000 Aperture stop AS (φ2 = 8.5)
9) -45.2494 1.5000 20.88 1.922860
* 10) -137.4241 1.6000
11) 581.3424 3.2000 81.61 1.497000
12) -29.2488 D12
13) 56.7832 3.0000 66.99 1.593490
14) -198.0567 3.6000
* 15) 59.9813 1.5000 19.32 2.001780
16) 37.6596 Bf
[Aspherical data]
K A2 A4 A6 A8
2nd surface 0.5221 0.00000E + 00 9.10090E-06 3.16360E-08 0.00000E + 00
10th surface -2.320E + 02 0.00000E + 00 1.37430E-05 1.04590E-07 0.00000E + 00
15th surface -20.6624 0.00000E + 00 9.94650E-07 -3.00770E-08 0.00000E + 00
[Variable interval data]
Infinite focusing state Short focusing state f, β 19.99994 -0.10000
D0 ∞ 194.7697
D5 2.00000 2.00000
D12 1.10000 1.30736
Bf 21.70495 23.57120
TL 79.40495 81.47856
[Lens group data]
Lens group Focal length G1 -218.315
G2 42.254
G3 211.003
[Conditional expression values]
(1) F12 / F3 = 0.117
(2) F2 / F3 = 0.200
(3) F1 / F3 = −1.035
(4) F3 / G3bR2 = 5.603
(5) G3aR2 / G3bR1 = −3.302
(6) F23 / F1 = −0.159
(7) F2 / Ri = −0.235
(8) X1 / X2 = 0.900

  Thus, in this embodiment, it can be seen that all the conditional expressions (1) to (8) are satisfied.

FIG. 4 is a diagram illustrating various aberrations of the imaging lens PL (2) according to the second example. 4A is a diagram showing various aberrations of the imaging lens PL (2) in the infinite focus state, and FIG. 4B is an imaging lens P.
FIG. 7 is a diagram illustrating various aberrations when L (2) is in a close focus state (closest shooting distance L = 276 mm). From the respective aberration diagrams, it can be seen that, in the second example, various aberrations are well corrected and the imaging performance is excellent. Further, excellent optical performance can be ensured also in an imaging device (for example, the camera CAM in FIG. 9) equipped with the imaging lens PL (2).

(Third embodiment)
FIG. 5 is a lens configuration diagram of the imaging lens PL (3) according to the third example in the infinitely focused state. This imaging lens PL (3) has a front lens group Gf having a weak refractive power, a first lens group G1 having a negative refractive power, and a positive refractive power, which are arranged in order from the object side along the optical axis. It is composed of a second lens group G2 and a third lens group G3 having a positive refractive power. The imaging lens PL (3) is a single focus lens, and the diagonal length from the center of the imaging element C corresponding to the imaging lens PL (3) to the diagonal (that is, the maximum image height on the imaging surface Ci) is 14. .3 mm. Further, the curvature radius Rc of the imaging surface Ci of the imaging element C curved in a spherical shape so that the concave surface is directed toward the object side is −145 mm with a positive value in the direction in which the concave surface is directed toward the image surface I side.

The front lens group Gf includes a negative meniscus lens having a convex surface directed toward the object side, and has a weak refractive power. The first lens group G1 includes a negative meniscus lens L1 having a convex surface facing the object side, a field stop FS, and a positive meniscus lens L2 having a convex surface facing the object side. Note that the image side surface of the negative meniscus lens L1 is an aspherical surface. The second lens group G2 includes a biconvex positive lens L3, a cemented positive lens of a negative meniscus lens L4 having a concave surface facing the object side, an aperture stop AS, a biconcave negative lens L5, and a biconvex positive lens. Consists of a lens L6. The object side surface of the negative lens L5 is an aspherical surface. The third lens group G3 includes a biconvex positive lens L7 and a biconcave negative lens L8. The object side surface of the negative lens L8 is an aspherical surface.
The focal length of the front lens group Gf is as weak as −63 times the focal length of the imaging lens PL, and is such that the specifications of the optical system composed of the first to third lens groups G1 to G3 are not changed.

  In the imaging lens PL (3), focusing from an infinite distance to a close object (finite distance object) is performed while reducing the distance between the first lens group G1 and the second lens group G2. The third lens group G1 to G3 is moved in the optical axis direction. During focusing, the first lens group G1 moves integrally as the first focusing group, the second lens group G2 and the third lens group G3 move integrally as the second focusing group, and the field stop FS is The aperture stop AS moves integrally with the first lens group G1, and the aperture stop AS moves integrally with the second lens group G2.

  Table 3 below shows various specifications in the third embodiment.

(Table 3)
[Specification data]
f = 13.2
FNO = 2.0
ω = 54.1 °
[Lens data]

Surface number R D νd nd
1) 1000.0000 1.0000 63.88 1.516800
2) 300.0000 D2
3) 136.5708 2.0000 63.86 1.618810
* 4) 8.8012 13.8000
5) ∞ 0.0000 Field stop FS (φ1 = 13.20)
6) 20.5000 2.3000 49.65 1.772500
7) 73.2838 D7
8) 24.1960 2.4000 52.34 1.755000
9) -104.0685 1.0000 32.31 1.953750
10) -1382.6803 3.5000
11) ∞ 1.8000 Aperture stop AS (φ2 = 12.00)
* 12) -186.9152 1.4000 20.88 1.922860
13) 42.6298 0.2000
14) 29.4719 2.7000 55.48 1.696800
15) -40.6621 D15
16) 210.1846 3.5000 81.61 1.497000
17) -16.7443 1.4000
* 18) -39.9247 1.7000 29.83 1.951500
19) 266.4593 Bf
[Aspherical data]
K A2 A4 A6 A8
4th surface 0.4876 0.00000E + 00 1.97220E-05 1.55720E-07 0.00000E + 00
12th surface -23.0204 0.00000E + 00 -6.58090E-05 -3.10270E-07 0.00000E + 00
18th surface 18.2106 0.00000E + 00 -5.03980E-05 -1.24340E-07 0.00000E + 00
[Variable interval data]
Infinity focusing state Short-distance focusing state f, β 13.20000 -0.10000
D0 ∞ 126.4315
D2 3.00001 1.80417
D7 1.10000 0.96713
D15 0.40000 0.40000
Bf 14.83969 16.16840
TL 58.03970 58.03970
[Lens group data]
Lens group focal length G1 -72.351
G2 25.015
G3 170.000
Gf-829.683
[Conditional expression values]
(1) F12 / F3 = 0.091
(2) F2 / F3 = 0.147
(3) F1 / F3 = −0.426
(4) F3 / G3bR2 = 0.638
(5) G3aR2 / G3bR1 = 0.419
(6) F23 / F1 = −0.304
(7) F2 / Ri = −0.173
(8) X1 / X2 = 0.900

  Thus, in this embodiment, it can be seen that all the conditional expressions (1) to (8) are satisfied.

FIG. 6 is a diagram illustrating various aberrations of the imaging lens PL (3) according to the third example. FIG. 6A is a diagram showing various aberrations when the imaging lens PL (3) is in focus at infinity, and FIG. 6B is a short distance focusing state of the imaging lens PL (3) (closest shooting distance L = 184 mm). FIG. From the respective aberration diagrams, it is understood that various aberrations are corrected well and excellent imaging performance is obtained also in the third example. Further, excellent optical performance can be ensured also in an imaging apparatus (for example, the camera CAM in FIG. 9) equipped with the imaging lens PL (3).

(Fourth embodiment)
FIG. 7 shows a lens configuration diagram of the imaging lens PL (4) according to the fourth example in an infinitely focused state. The imaging lens PL (4) includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a positive refraction arranged in order from the object side along the optical axis. The third lens group G3 having power and the rear lens group Gr having weak refractive power are configured. The imaging lens PL (4) is a single focus lens, and the diagonal length from the center of the imaging device C corresponding to the imaging lens PL (4) to the diagonal (that is, the maximum image height on the imaging plane Ci) IH is 3. 96 mm. Further, the curvature radius Rc of the imaging surface Ci of the imaging element C curved in a spherical shape so that the concave surface is directed toward the object side is −33 mm, with a value in the direction in which the concave surface is directed toward the image surface I being a positive value.

The first lens group G1 includes a negative meniscus lens L1 having a convex surface facing the object side, and a positive meniscus lens L2 having a convex surface facing the object side. Note that the image side surface of the negative meniscus lens L1 is an aspherical surface. The second lens group G2 includes a positive meniscus lens L3 having a convex surface facing the object side, an aperture stop AS, a negative meniscus lens L4 having a concave surface facing the object side, and a biconvex positive lens L5. . Note that the image-side surface of the negative meniscus lens L4 is an aspherical surface. The third lens group G3 includes a biconvex positive lens L6 and a negative meniscus lens L7 having a concave surface directed toward the object side. The object side surface of the negative meniscus lens L7 is an aspherical surface. The rear lens group Gr includes a negative meniscus lens having a concave surface directed toward the object side, and has a weak refractive power. The focal length of the rear lens group Gr is as weak as -221 times the focal length of the imaging lens PL, and is such that the specifications of the optical system composed of the first to third lens groups G1 to G3 are not changed.

  In the imaging lens PL (4), focusing from an infinite distance to an object at a close distance (a finite distance object) is performed while reducing the distance between the first lens group G1 and the second lens group G2. The third lens group G1 to G3 is moved in the optical axis direction. During focusing, the first lens group G1 moves integrally as a first focusing group, the second lens group G2 and the third lens group G3 move integrally as a second focusing group, and the aperture stop AS is It moves integrally with the second lens group G2.

  Table 4 below shows specifications of the fourth embodiment.

(Table 4)
[Specification data]
f = 3.7
FNO = 2.0
ω = 53.8 °
[Lens data]
Surface number R D νd nd
1) 26.8149 1.0000 49.32 1.743300
2) 2.8536 3.8000
3) 6.7696 1.5000 35.25 1.910820
* 4) 22.9875 D4
5) 9.3796 1.1000 52.34 1.755000
6) 17.9616 0.7000
7) ∞ 0.5000 Aperture stop AS (φ2 = 3.42)
8) -15.9890 0.8000 20.88 1.922860
* 9) -123.3879 0.3000
10) 8.3868 2.2000 66.99 1.593490
11) -6.7503 D11
12) 12.2014 2.2000 81.61 1.497000
13) -6.3422 0.4000
* 14) -9.1260 1.0000 19.32 2.0017800
15) -93.8664 D15
16) -450.0000 0.8000 25.46 2.000690
17) -1000.0000 Bf
[Aspherical data]
K A2 A4 A6 A8
4th surface 0.3905 0.00000E + 00 -4.38850E-05 4.73680E-05 0.00000E + 00
9th surface -4.383E + 03 0.00000E + 00 1.65550E-03 1.01860E-04 0.00000E + 00
14th surface 5.9078 0.00000E + 00 -1.21760E-03 1.58800E-05 0.00000E + 00
[Variable interval data]
Infinite focusing state Short focusing state f, β 3.69999 -0.10000
D0 ∞ 35.1559
D4 0.35000 0.25725
D11 0.10000 0.10000
D15 0.20000 0.57100
Bf 3.14156 3.14156
TL 20.09156 20.36981
[Lens group data]
Lens group focal length G1-19.197
G2 7.572
G3 38.929
Gr-818.213
[Conditional expression values]
(1) F12 / F3 = 0.120
(2) F2 / F3 = 0.195
(3) F1 / F3 = −0.493
(4) F3 / G3bR2 = −0.415
(5) G3aR2 / G3bR1 = 0.695
(6) F23 / F1 = −0.324
(7) F2 / Ri = −0.229
(8) X1 / X2 = 0.750

  Thus, in this embodiment, it can be seen that all the conditional expressions (1) to (8) are satisfied.

  FIG. 8 is a diagram illustrating various aberrations of the imaging lens PL (4) according to the fourth example. FIG. 8A is a diagram showing various aberrations when the imaging lens PL (4) is in focus at infinity, and FIG. 8B is a short distance focusing state of the imaging lens PL (4) (closest shooting distance L = 56 mm). FIG. From the respective aberration diagrams, it is understood that various aberrations are corrected well and excellent imaging performance is obtained also in the fourth example. In addition, excellent optical performance can be ensured even in an imaging device (for example, the camera CAM in FIG. 9 and the like) equipped with the imaging lens PL (4).

In each of the embodiments described above, camera shake correction may be performed by moving all or part of the second lens group in a direction substantially perpendicular to the optical axis.
If the focusing mechanism is simplified, the first to third lens groups G1 to G3 may be moved integrally in the optical axis direction to be focused.
The cemented lens used in the first to third embodiments may be separated.
Although the front lens group Gf of the third embodiment is fixed at the time of focusing, it may be configured to move in the axial direction integrally or separately from the first lens group.
Although the rear lens group Gr of the fourth embodiment is fixed at the time of focusing, it may be configured to move in the axial direction integrally with or separately from the third lens group.

  As described above, according to each of the embodiments, although having a simple configuration, a wide angle of view (for example, ω is larger than 45 °, more preferably larger than 50 °) and an F number is small (for example, FNO is about 2. An imaging lens smaller than 8 (more preferably, FNO is smaller than about 2.0) and a digital still camera (imaging device) including the same can be realized.

  In addition, in the above-mentioned embodiment and an Example, the content of the following description is employable suitably in the range which does not impair optical performance.

  In each of the above-described embodiments, the imaging element C having the imaging surface Ci curved in a spherical shape so that the concave surface is directed toward the object side is illustrated as the imaging element corresponding to the imaging lens PL, but is not limited thereto. . For example, the imaging surface Ci of the imaging element C may be formed to be aspherical or elliptical so that the concave surface faces the object side.

  Each lens may be formed of a glass material, a resin material, or a composite of a glass material and a resin material.

  The lens surface may be formed as a spherical surface, a flat surface, or an aspheric surface. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment are facilitated, and optical performance deterioration due to errors in processing and assembly adjustment can be prevented. When the lens surface is an aspheric surface, the aspheric surface is an aspheric surface by grinding, a glass mold aspheric surface made of glass with an aspheric shape, or a composite aspheric surface made of resin with an aspheric shape on the glass surface. Any aspherical surface may be used. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

  Although the aperture stop AS is disposed in the second lens group G2, a role of a lens frame may be substituted without providing a member as an aperture stop. Similarly, the field stop FS may be replaced by a lens frame or a light shielding plate without providing a member as a field stop.

  Each lens surface may be provided with an antireflection film in order to reduce flare and ghost and achieve high optical performance. The antireflection film can be appropriately selected, and may be an antireflection film having a multilayer coating or an ultra-low refractive index layer made of fine crystal particles. Further, the number of lens surfaces on which the antireflection film is applied is not particularly limited.

  In the above-described embodiment, the digital still camera CAM in which the imaging lens PL and the camera body (imaging device C) are integrally formed is used as the imaging device including the imaging lens PL. However, the present invention is not limited to this. is not. For example, a digital single-lens reflex camera in which the imaging lens PL and the camera body are configured to be detachable can be used as the imaging device including the imaging lens PL. Further, for example, a camera mounted on a portable terminal or the like may be used as the imaging device including the imaging lens PL. Further, for example, as an imaging apparatus including the imaging lens PL, an imaging apparatus including at least the imaging lens PL and the imaging element C may be used without including the liquid crystal monitor M and the operation member. In addition, it is not limited to providing each structure part mentioned above, Arbitrary combinations may be sufficient.

CAM digital still camera (imaging device)
C Image sensor (Ci imaging surface)
PL imaging lens G1 first lens group G2 second lens group G3 third lens group FS field stop AS aperture stop I image plane

Claims (17)

An imaging lens that forms an image of an object on an imaging surface curved with a concave surface facing the object side,
A first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power, arranged in order from the object side;
The first lens group includes one or more positive lenses and one or more negative lenses,
The second lens group has two or more positive lenses, one or more negative lenses, and an aperture stop.
The third lens group has one or more positive lenses and one or more negative lenses,
An imaging lens that satisfies the following conditional expression.
0.03 <F12 / F3 <0.30
F12: the combined focal length of the first lens group and the second lens group at infinity,
F3: focal length of the third lens group. The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
0.05 <F2 / F3 <0.40
F2: focal length of the second lens group. The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
-10.00 <F1 / F3 <-0.10
F1: A focal length of the first lens group. The imaging lens according to any one of claims 1 to 3, wherein the following conditional expression is satisfied.
-3.00 <F3 / G3bR2 <7.00
G3bR2: radius of curvature of the image side surface of the final negative lens arranged closest to the image plane among the negative lenses included in the third lens group. The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
-5.00 <G3aR2 / G3bR1 <1.50
However, G3bR1: the radius of curvature of the object side surface of the final negative lens arranged closest to the image plane among the negative lenses included in the third lens group,
G3aR2: the radius of curvature of the image-side surface of the lens disposed at the position facing the object side of the final negative lens. The imaging lens according to any one of claims 1 to 5, which satisfies the following conditional expression.
-0.50 <F23 / F1 <-0.01
F23: The combined focal length of the second lens group and the third lens group at infinity.   The imaging lens according to claim 1, wherein the first lens group includes a negative lens closest to the object side.   The imaging lens according to claim 1, wherein the second lens group includes a positive lens closest to the object side and a positive lens closest to the image plane.   The imaging lens according to claim 1, wherein the third lens group has a negative lens closest to the image plane. The imaging lens according to any one of claims 1 to 9, which satisfies the following conditional expression.
−0.40 <F2 / Ri <−0.05
Ri: the radius of curvature of the imaging surface curved with the concave surface facing the object side. The first lens group, the second lens group, and the third lens group are disposed on the image side of the first focusing group that moves in the optical axis direction during focusing and the first focusing group. And a second focusing group that moves in the optical axis direction along a different path from the first focusing group at the time of focusing.
The imaging lens according to any one of claims 1 to 10, which satisfies the following conditional expression.
0.60 <X1 / X2 <1.10
Where X1: the amount of movement of the first focusing group when focusing from an object at infinity to a near object,
X2: The amount of movement of the second focusing group when focusing from an object at infinity to a near object.   The imaging lens according to any one of claims 1 to 11, wherein a field stop is disposed in the first lens group.   The imaging lens according to claim 1, wherein at least one surface of each of the first, second, and third lens groups has an aspherical shape. The imaging lens according to any one of claims 1 to 13,
An image pickup apparatus comprising: an image pickup device that picks up an image formed on the image pickup surface.   The imaging device according to claim 14, wherein a light splitting optical element is not provided between the imaging lens and the imaging element.   The imaging apparatus according to claim 14 or 15, wherein the imaging lens and the imaging element are integrally configured. An imaging lens manufacturing method for forming an image of an object on an imaging surface curved with a concave surface facing the object side,
In the lens barrel, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power are arranged in order from the object side. Has steps,
In the step, the first lens group includes one or more positive lenses and one or more negative lenses, and the second lens group includes two or more positive lenses, one or more negative lenses, and an aperture. The third lens group has an aperture, and the third lens group has one or more positive lenses and one or more negative lenses, and each lens is arranged in a lens barrel so as to satisfy the following conditional expression: Lens manufacturing method.
0.03 <F12 / F3 <0.30
F12: the combined focal length of the first lens group and the second lens group at infinity,
F3: focal length of the third lens group.