JP5796466B2 - Imaging lens and imaging apparatus having the imaging lens - Google Patents

Description

  The present invention relates to a photographic lens and an imaging apparatus having the photographic lens.

  Specifically, the imaging lens is a general camera lens, a monitoring lens for ensuring safety indoors and outdoors, a mobile device such as an in-vehicle vehicle interior and exterior, and a vehicle body image information acquisition lens. Includes aircraft security lenses, robot eye lenses, astronomical lenses, and more. The lenses used for these are required to have a wide angle of view, sharp resolution, and a small number of ghosts that can cope with luminance differences. For this purpose, an optical system that is simple and corrects aberrations with a small air interface is required. An example of such an optical system is described in Patent Document 1.

JP 2008-268268 A

  However, in order to meet the above requirements, high resolution is the most necessary condition as a means for obtaining a high-quality image. However, when a wide angle of view is realized, the illuminance around the visual field is reduced by the cosine fourth law. There was a problem.

  The present invention has been made in view of such a problem, and a photographing lens capable of realizing a wide angle of view, good aberration correction, and a small number of ghosts capable of dealing with a luminance difference, and an imaging apparatus having the photographing lens. The purpose is to provide.

In order to solve the above problems, a photographic lens according to the present invention has, in order from the object side, a negative meniscus lens shape with a concave surface facing the image side, a first lens component having negative refractive power, and an image side. A second lens component having negative refractive power and a negative refractive power, a third lens component having a biconvex lens shape and having positive refractive power, and a second lens component having positive refractive power and having a convex surface facing the image side. 4 lens components, and all the lens components are single lenses, and satisfy the condition of the following formula.
1.0 <f1 / f2 <2.6
2.9 <f4 / f <4.2
-1.15 <(r4 + r3) / (r4-r3) <0.2
−0.7 <(r6 + r5) / (r6-r5) <− 0.07
However,
f: focal length of the entire system f1: focal length of the first lens component f2: focal length of the second lens component f4: focal length of the fourth lens component r3: radius of curvature of the lens surface closest to the object side of the second lens component r4: radius of curvature of the lens surface closest to the image side of the second lens component
r5: radius of curvature of the lens surface closest to the object side of the third lens component
r6: radius of curvature of the lens surface closest to the image side of the third lens component

Moreover, it is preferable that such a photographic lens satisfies the following condition.
0.78 <f3 / f4 <1.30
However,
f3: focal length of the third lens component

Moreover, it is preferable that such a photographic lens satisfies the following condition.
1.61 <(n3 + n4) / 2 <1.82
However,
n3: refractive index for the fourth lens component of the medium P line (λ = 940nm): third lens component of the medium P line (lambda = 940 nm) refractive index for n4

  In addition, such a photographic lens preferably has a stop between the third lens component and the fourth lens component.

  Further, such a photographing lens preferably has a maximum angle of view of light rays contributing to image formation of 120 degrees or more.

  Moreover, it is preferable that such a photographic lens has a negative distortion.

  An imaging apparatus according to the present invention includes any one of the above-described photographing lenses.

  According to the present invention, it is possible to provide a photographing lens capable of realizing a wide angle of view, good aberration correction, and a small number of ghosts that can cope with a luminance difference, and an imaging device having this photographing lens.

It is sectional drawing which shows the lens structure of the imaging lens which concerns on 1st Example. FIG. 6 is a diagram illustrating all aberrations of the taking lens according to the first example. It is sectional drawing which shows the lens structure of the imaging lens which concerns on 2nd Example. FIG. 6 is a diagram illustrating all aberrations of the taking lens according to the second example. It is sectional drawing which shows the lens structure of the imaging lens which concerns on 3rd Example. FIG. 12 is a diagram illustrating all aberrations of the taking lens according to the third example. It is sectional drawing which shows the lens structure of the imaging lens which concerns on 4th Example. FIG. 10 is a diagram illustrating all aberrations of the taking lens according to the fourth example. It is sectional drawing which shows the lens structure of the imaging lens which concerns on 5th Example. FIG. 10 is a diagram illustrating all aberrations of the taking lens according to the fifth example. It is sectional drawing which shows the lens structure of the imaging lens which concerns on 6th Example. FIG. 10 is a diagram illustrating all aberrations of the taking lens according to the sixth example. It is sectional drawing which shows the lens structure of the imaging lens which concerns on 7th Example. FIG. 10 is a diagram illustrating all aberrations of the taking lens according to the seventh example. It is a block diagram which shows the structure of an imaging device.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the photographic lens SL according to the present embodiment is designed to realize a bright optical system having a wide angle with an incident angle of 60 degrees or more (maximum field angle of 120 degrees or more) and a brightness exceeding F / 4. In order from the side, the first lens component LC1 has a negative meniscus lens shape with a concave surface facing the image side and has a negative refractive power, and the second lens component LC2 has a negative surface and a negative surface with the concave surface facing the image side. And a third lens component LC3 having a biconvex lens shape and having a positive refractive power, and a fourth lens component LC4 having a convex surface facing the image side and having a positive refractive power. In the photographing lens SL, a diaphragm S is disposed between the third lens component LC3 and the fourth lens component LC4. In the following description, “lens component” refers to a single lens (lens element) or a cemented lens in which two or more single lenses (lens elements) are cemented.

  In this photographic lens SL, two lens components (first lens component LC1 and second lens component LC2) having negative refractive power arranged from the object side are configured to gradually receive incident light rays from a wide incident angle as optical axes. It has the function of passing through the aperture position by converting to a small angle along the aperture. Since light rays from a large incident angle pass through the end of the lens, in order to minimize the meridional field curvature that occurs in the positive direction, it is necessary for all lenses to have a concave surface facing the image side. Furthermore, at least the first lens component LC1 located closest to the object side has a particularly large incident angle, and therefore needs to have a meniscus shape with a convex surface facing the object side.

  The third lens component LC3 and the fourth lens component LC4 arranged next to the first and second lens components LC1 and LC2 are positive lens components arranged before and after the stop S, and It has a function of converging light rays diverged by the first and second lens components LC1 and LC2 which are negative lens components. In order to obtain a bright effective F-number, at least two positive lens components are necessary, and the negative Petzval sum generated in the first lens component LC1 and the second lens component LC2 is converted into these third lens components LC3. The positive Petzval sum generated by the fourth lens component LC4 is canceled.

  Now, conditions for configuring such a photographing lens SL will be described. First, it is desirable that the photographic lens SL according to the present embodiment satisfies the following conditional expression (1).

1.0 <f1 / f2 <2.6 (1)
However,
f1: Focal length of the first lens component LC1 f2: Focal length of the second lens component LC2

  Conditional expression (1) defines the focal length ratio of the first lens component LC1 and the second lens component LC2 which are two lens components having a diverging action. Needless to say, the back focus of the entire system of the photographing lens SL is ensured by the diverging action of the two negative lens components. When the ratio of the focal lengths of the first and second lens components LC1 and LC2 is changed while maintaining the divergent state for ensuring the back focus, the distance from the aperture stop S is exceeded if the lower limit value of the conditional expression (1) is exceeded. The divergent force of the first lens component LC1 at a distance becomes relatively large, and distortion aberration is strongly negatively induced. Therefore, the lower limit value of the conditional expression (1) defines the requirement that the negative refractive power of the first lens component LC1 is lower than the negative refractive power of the second lens component LC2. Although it seems that it is reasonable for the photographic lens SL to make the refractive powers of the first and second lens components LC1 and LC2 uniform in terms of aberration correction, the present inventor considered that the first lens component LC1 is divergent. It has been found that it is preferable for the aberration balance of the entire system to make the force smaller than the divergent force of the second lens component LC2.

  When the lower limit value of conditional expression (1) is exceeded, distortion is excessively negative and the total correction action of the two negative lens components (first and second lens components LC1, LC2) is weak. The Petzval sum of the entire system is insufficiently corrected and cannot be corrected. Further, when the upper limit value of the conditional expression (1) is exceeded, excessive negative distortion does not occur, but the action of the first lens component LC1 is weakened and an excessive burden is placed on the second lens component LC2. The sum becomes overcorrected, and the meridional field curvature aberration becomes excessively positive and cannot be corrected.

  In addition, it is desirable that the photographic lens SL according to the present embodiment satisfies the following conditional expression (2).

2.9 <f4 / f <4.2 (2)
However,
f4: focal length of the fourth lens component LC4 f: focal length of the entire system

  The photographic lens SL according to the present embodiment includes a first lens component LC1 having a negative meniscus lens shape with a concave surface facing the image side and a second lens component having a concave surface facing the image side. A substantially inverse Galileo optical system composed of the LC2 and the third lens component LC3 having a biconvex lens shape is arranged, and this arrangement ensures correction of aberrations including field curvature aberration and back focus appropriately. On the other hand, the fourth lens component LC4 having a positive refractive power arranged as a rear group on the image side from the stop S functions as a condenser lens, and appropriately corrects the combined focal length and F number of the entire system. And a function of canceling out coma remaining in the front group in a well-balanced manner.

  Conditional expression (2) defines the focal length of the fourth lens component LC4 having such a function as a ratio with respect to the focal length of the entire system of the photographing lens SL. The upper limit value of the conditional expression (2) is defined as the conditional expression (2). If it exceeds, the condensing power of the fourth lens component LC4 is weakened, so that the internal coma aberration becomes strong and cannot be corrected satisfactorily. On the other hand, when the lower limit value of conditional expression (2) is exceeded, the condensing power of the fourth lens component LC4 becomes too strong and the external coma aberration becomes strong and cannot be corrected well.

  In addition, it is desirable that the photographic lens SL according to the present embodiment satisfies the following conditional expression (3).

-1.15 <(r4 + r3) / (r4-r3) <0.2 (3)
However,
r3: radius of curvature of the lens surface closest to the object side of the second lens component LC2 r4: radius of curvature of the lens surface closest to the image side of the second lens component LC2

  Conditional expression (3) defines the bending shape of the second lens component LC2. Defining the bending shape of the second lens component LC2 is effective for correcting coma with a good balance among various aberrations. Here, since the second lens component LC2 has a concave meniscus shape in which the most object side lens surface is convex with respect to the object, the most image side lens surface is the most object side by this conditional expression (3). The lens surface can take a shape up to a biconcave lens with a gentler curvature than the lens surface.

  When the lower limit value of the conditional expression (3) is exceeded, the concave curvature of the concave surface of the image side lens surface of the second lens component LC2 becomes a negative meniscus shape, and the resulting diverging action of the most image side lens surface becomes too strong. . For this reason, the divergent action of the light beam passing through the edge of the lens is stronger than the position through which the chief light beam passes, and the coma aberration cannot be corrected. Further, since the spherical aberration is positively increased and the meridional field curvature is also positively increased, the aberration balance of the entire system is deteriorated and the aberration cannot be corrected well. When the upper limit value of the conditional expression (3) is exceeded, the curvature of the lens surface closest to the object side is stronger than that of the lens surface closest to the image side. In this case, however, the diverging action of the lens surface on the object side is too strong, so that the diverging action of the light ray passing through the lens edge side becomes stronger than the principal ray, and the coma aberration cannot be corrected. Further, since the divergent force of the lens surface closest to the image becomes too weak, the spherical aberration becomes negative, and the aberration balance of the entire system cannot be corrected well.

  In addition, it is desirable that the photographic lens SL according to the present embodiment satisfies the following conditional expression (4).

0.78 <f3 / f4 <1.30 (4)
However,
f3: focal length of the third lens component LC3 f4: focal length of the fourth lens component LC4

  Conditional expression (4) defines the relationship between the third lens component LC3 and the fourth lens component LC4, which are two converging lenses that sandwich the stop S. The photographic lens SL according to the present embodiment increases the angle of view with the first and second lens components LC1 and LC2, and the third and fourth lens components LC3 and LC4 with the first and second lens components LC1 and LC2. It plays the role of converging the divergent rays. This conditional expression (4) is limited to a value between 1 and 1 because the general converging action before and after the aperture stop S is symmetrical, and this converging action is equally distributed as much as possible to generate higher-order aberrations. It shows that it was prevented to the minimum.

  When the lower limit of conditional expression (4) is exceeded and the refractive power of the third lens component LC3 located on the object side from the stop S is increased, negative spherical aberration and coma of the light ray passing through the periphery of the third lens component LC3 are generated. Deteriorated and cannot be corrected. Further, when the upper limit value of the conditional expression (4) is exceeded and the refractive power of the fourth lens component LC4 becomes relatively strong, the coma aberration of the light beam passing through the periphery of the fourth lens component LC4 deteriorates and is corrected. I don't get it. In order to correct the coma aberration and spherical aberration in the entire field of view more satisfactorily, it is desirable that the third lens component LC3 and the fourth lens component LC4 are aspherical lenses. It is preferable that at least one aspheric surface is provided on both surfaces arranged at symmetrical positions of the third lens component LC3 and the fourth lens component LC4 with the stop S interposed therebetween, and in particular, the object of the third lens component LC3. It is preferable to apply an aspherical surface to the side surface and the image side surface of the fourth lens component LC4.

  Under the above four conditions, a wide-angle lens (photographing lens SL) having an incident angle of 60 degrees or more (maximum field angle of 120 degrees or more) and a brightness of F / 4 can be realized. Furthermore, in order to further improve the resolution characteristics, it is preferable to satisfy the following conditions. That is, it is desirable that the photographic lens SL according to the present embodiment satisfies the following conditional expression (5).

−0.7 <(r6 + r5) / (r6-r5) <− 0.07 (5)
However,
r5: radius of curvature of the lens surface closest to the object side of the third lens component LC3 r6: radius of curvature of the lens surface closest to the image side of the third lens component LC3

  Conditional expression (5) defines the bending shape of the third lens component LC3. The lens surface on the image side of the third lens component LC3 has a biconvex lens shape with a convex surface facing the image side and a smaller radius of curvature than the object side surface. When the bending shape exceeds the lower limit value of the conditional expression (5), the condensing power of the lens surface on the image side of the third lens component LC3 works more strongly, and the main point of the third lens component LC3 is the front group. The back focus increases, the Petzval sum increases negatively (overcorrection), and positive coma remains. Thus, the aberration balance cannot be kept good. If the upper limit of conditional expression (5) is exceeded, negative coma occurs and cannot be corrected.

  In addition, it is desirable that the photographic lens SL according to the present embodiment satisfies the following conditional expression (6).

1.61 <(n3 + n4) / 2 <1.82 (6)
However,
n3: Refractive index of the medium of the third lens component LC3 n4: Refractive index of the medium of the fourth lens component LC4

  Conditional expression (6) defines an average refractive index value of the third lens component LC3 and the fourth lens component LC4, which are lens components having positive refractive power, and tries to keep the Petzval sum of the entire system well. To do. When the upper limit value of the conditional expression (6) is exceeded, the Petzval sum of the entire system becomes negative (overcorrection), which is not preferable. Further, when this conditional expression (6) exceeds the lower limit, the Petzval sum becomes positive (undercorrection), which is not preferable. In the conditional expression (6), when the third lens component LC3 and the fourth lens component LC4 are cemented lenses, the refractive index of each lens component is the average of the refractive indexes of the lens elements included in the lens component. Value.

  By providing the photographic lens SL according to the present embodiment with the above-described configuration, it is possible to provide a photographic lens that has a very small size and a wide field of view, and that has excellent aberration correction over the entire field of view, and has few ghosts. Can do.

  Note that the photographic lens SL according to the present embodiment has a good resolving power by configuring each of the first lens component LC1, the second lens component LC2, the third lens component LC3, and the fourth lens component LC4 with a single lens. The minimum number of components can be achieved, and an increase in size can be avoided. Further, the photographic lens SL is composed of four elements in four groups including only the first lens component LC1, the second lens component LC2, the third lens component LC3, and the fourth lens component LC4, so that the above-described effects can be further exerted. be able to. In this case, the photographing lens SL allows negative image distortion.

  In addition, the contents described below can be employed as appropriate within a range that does not impair the optical performance.

  In the present embodiment, the photographic lens SL composed of four and five lens components is shown. However, the above-described configuration conditions and the like can also be applied to a configuration having six or more lens components. Further, a configuration in which a lens or a lens group is added closest to the object side, a configuration in which a lens or a lens group is added closest to the image side, or a configuration in which a lens group is added between lens components may be used. In addition, as described in the above embodiment, the lens group is separated by a portion having at least one lens separated by the aperture S, or by an air interval that changes at the time of zooming or focusing. , Showing a portion having at least one lens.

  In addition, a single lens group or a plurality of lens groups or partial lens groups of the photographing lens SL may be moved in the optical axis direction to be a focusing lens group that performs focusing from an object at infinity to a near object. In this case, the focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (using an ultrasonic motor or the like).

  Also, by moving the lens group or partial lens group so that it has a component in the direction perpendicular to the optical axis, or rotating (swinging) in the in-plane direction including the optical axis, image blur caused by camera shake is corrected. An anti-vibration lens group may be used. In particular, it is preferable that the third lens component LC3 and the fourth lens component LC4 are integrated into a vibration-proof lens group.

  Further, the lens surface may be formed as a spherical surface, a flat surface, or an aspheric surface. It is preferable that the lens surface is a spherical surface or a flat surface because lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to errors in processing and assembly adjustment is prevented. Further, even when the image plane is shifted in the optical axis direction, it is preferable because there is little deterioration in the drawing performance. 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 on the glass surface. Any of the aspherical surfaces 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.

  The diaphragm S is preferably disposed between the third lens component LC3 and the fourth lens component LC4 as described above, but instead of providing a member as a diaphragm, the role of the lens frame is substituted. May be.

  Further, each lens surface may be provided with an antireflection film having a high transmittance in a wide wavelength range in order to reduce flare and ghost and achieve high optical performance with high contrast.

  FIG. 15 shows a configuration of an in-vehicle observation apparatus 10 that is an example of an imaging apparatus in which the photographing lens SL according to the present embodiment is mounted. The in-vehicle observation apparatus 10 is mounted on, for example, an automobile and is used for photographing a situation in front of the vehicle (external space) through the window shield W. The in-vehicle observation apparatus 10 generates an image of a subject from the above-described photographing lens SL, the imaging element 1 arranged on the image plane of the photographing lens SL, and an electric signal (image signal) output from the imaging element 1. And an image storage unit 3 for storing the image generated by the image processing unit 2.

  Hereinafter, embodiments of the photographing lens SL will be described with reference to the drawings. 1, 3, 5, 7, 9, 11, and 13 illustrate the configuration of the photographic lens SL (SL <b> 1 to SL <b> 7) according to each example.

In each embodiment, the height of the aspheric surface in the direction perpendicular to the optical axis is y, and the distance (sag amount) along the optical axis from the tangential plane of the apex of each aspheric surface to each aspheric surface at height y. Is S (y), r is the radius of curvature of the reference sphere (paraxial radius of curvature), κ is the conic constant, and An is the nth-order aspherical coefficient, and is expressed by the following equation (a). . In the following examples, “E−n” indicates “× 10 ⁻ⁿ ”.

S (y) = (y ² / r) / [1+ {1− (κ + 1) (y ² / r ² )} ^1/2 ]
+ A4 × y ⁴ + A6 × y ⁶ + A8 × y ⁸ + A10 × y ¹⁰ (a)

  In each embodiment, the secondary aspheric coefficient A2 is zero. In the table of each example, an aspherical surface is marked with * on the right side of the surface number.

[First embodiment]
FIG. 1 is a diagram illustrating a configuration of a photographic lens SL1 according to the first example. The photographing lens SL1 is composed of a negative meniscus aspherical negative lens L1 having a concave surface facing the image side in order from the object side, the first lens component LC1 having negative refractive power, and the concave surface facing the image side. A second lens component LC2 having a negative refractive power, a third aspherical lens L3 having a positive refractive power, a stop S, The lens includes a convex aspherical positive lens L4, and a fourth lens component LC4 having a positive refractive power and a convex surface facing the image side. A cover glass CG is disposed between the photographing lens SL1 and the image plane I. The cover glass CG is a parallel plane transmissive member, and there is no fluctuation in the focal length depending on the presence or absence of the cover glass CG. However, since slight aberration fluctuation occurs, the first embodiment is optimized including the cover glass CG. Even if this cover glass CG is optically equivalently replaced with a color filter or a low-pass filter, or is divided or shared, there is no influence on the aberration.

  In the first embodiment, the image side lens surface (second surface) of the aspheric negative lens L1, the object side lens surface (fifth surface) of the aspheric positive lens L3, and the image of the aspheric positive lens L4. The side lens surface (ninth surface) is aspherical. Here, the aspherical surface of the aspherical negative lens L1 is mainly used for distortion control, and the object-side lens surface of the aspherical positive lens L3 and the image-side lens surface of the aspherical positive lens L4 are with respect to the stop S. It is used in a pair of symmetrical positional relations and contributes to further correction of coma aberration.

  Table 1 below lists values of specifications of the photographing lens SL1 according to the first example. In the overall specifications of Table 1, f represents the focal length of the entire system, FNO represents the F number, 2ω represents the maximum field angle, and ymax represents the image height corresponding to the maximum field angle of the photographing lens SL. . In the lens data, the first column m indicates the order (surface number) of the optical surfaces from the object side along the traveling direction of the light beam, the second column r indicates the curvature radius of each optical surface, Column d is the distance on the optical axis (surface spacing) from each optical surface to the next optical surface, column 4 νd is the Abbe number for the d-line (wavelength λ = 587.6 nm), column 5 nd Represents the refractive index for the d-line, and the sixth column nP represents the refractive index for the P-line (λ = 940 nm). The aspheric data shows the values of the above-mentioned aspheric conical constant κ and the aspheric constants A4 to A10. It should be noted that the focal length f of the entire system described above is included, and the focal lengths shown below all indicate values for the P line. The surface numbers 1 to 11 shown in Table 1 correspond to the numbers 1 to 11 shown in FIG. A radius of curvature of 0.0000 indicates a plane on the lens surface and an aperture on the stop S. Further, the refractive index of air of 1.0000 is omitted. The distance between the final surfaces (the eleventh surfaces) is the distance on the optical axis to the image surface I.

  Here, the focal length f, the radius of curvature r, the surface interval d, and other length units listed in all the following specification values are generally “mm”, but the optical system is proportionally enlarged or proportional. Since the same optical performance can be obtained even if the image is reduced, the present invention is not limited to this. The description of these symbols and the description of the specification table are the same in the following embodiments.

(Table 1)
[Overall specifications]
f = 1
FNO = 1.8
2ω = 170 degrees ymax = 1.337

[Lens data]
m rd νd nd nP
1 16.59253 0.69311 46.064 1.8048830 1.7881940
2 * 3.38331 1.32030
3 0.00000 0.69311 40.499 1.8090000 1.7903450
4 1.82691 1.67506
5 * 6.72973 2.45801 61.201 1.5890000 1.5791350
6 -3.10503 0.42357
7 0.00000 0.42357 Aperture S
8 7.33150 2.10997 40.499 1.8090000 1.7903450
9 * -3.93088 1.67034
10 0.00000 0.92414 67.817 1.4584400 1.4511770
11 0.00000 0.41592

[Aspherical data]
Second surface κ = -0.48343 A4 = -2.96197E-03 A6 = -3.71395E-05
A8 = -7.52975E-06 A10 = -4.66440E-07
5th surface κ = -77.877 A4 = 9.57960E-03 A6 = -1.30070E-02
A8 = 3.48097E-03 A10 = -4.99619E-04
9th surface κ = -2.7813 A4 = 5.03420E-03 A6 = -8.86001E-04
A8 = 9.36497E-04 A10 = -2.32748E-04

  Table 2 below shows the focal length of the photographic lens SL1 according to the first example and the values (condition corresponding values) corresponding to the above-described conditional expressions. In Table 2, f is the focal length of the entire system, f1 is the focal length of the first lens component LC1, f2 is the focal length of the second lens component LC2, f3 is the focal length of the third lens component LC3, and f4 is The focal length of the fourth lens component LC4, f12 is the combined focal length of the first lens component LC1 and the second lens component LC2, f123 is the combined focal length of the first to third lens components LC1 to LC3, and f34 is the third lens component. The combined focal length of LC3 and the fourth lens component LC4 is shown. These descriptions are the same in the following embodiments. The condition corresponding value for conditional expression (6) is calculated from the refractive index of the medium of the aspherical positive lens L3 and the aspherical positive lens L4 with respect to the P-line.

(Table 2)
f = 1.000
f1 = -5.520
f2 = -2.312
f3 = 4.039
f4 = 3.530
f12 = -1.352
f123 = 9.857
f34 = 2.668
(1) f1 / f2 = 2.388
(2) f4 / f = 3.530
(3) f3 / f4 = 1.144
(4) (r4 + r3) / (r4-r3) = − 1.0
(5) (r6 + r5) / (r6-r5) = − 0.369
(6) (n3 + n4) /2=1.85

  Thus, the photographic lens SL1 according to the first example satisfies all the conditional expressions (1) to (6) described above.

  FIG. 2 shows various aberration diagrams of spherical aberration, curvature of field, distortion, and coma of the taking lens SL1 according to the first example. In these various aberration diagrams, the highest value on the vertical axis of spherical aberration indicates H (the height of incident light), and the highest value on the vertical axis of curvature of field and distortion is ω (half field angle of the maximum field angle). The maximum value of the horizontal axis of coma aberration is the radius of the entrance pupil (when the incident angle is 0, the height H of the incident light beam). In the field curvature, a thick line (dark line) indicates a sagittal image plane, and a thin line (light color line) indicates a meridional (tangential) image plane. The unit of dimension is mm, and the focal length is normalized to 1 mm. Further, the distortion aberration indicates an aberration amount based on y = f * ω. As is apparent from the respective aberration diagrams shown in FIG. 2, it can be seen that the photographic lens SL1 according to Example 1 has various aberrations corrected well and has high optical performance.

  The photographic lens SL1 according to the first example is optimized in the near infrared region having a center wavelength of 940 nm (P line) and a wavelength range of ± 100 nm, but even with visible light having a center wavelength of 587.6 nm (d line). Aberrations have been corrected.

[Second Embodiment]
FIG. 3 is a diagram illustrating a configuration of the photographic lens SL2 according to the second example. The photographing lens SL2 is composed of a negative meniscus lens L1 having a concave surface directed toward the image side in order from the object side, and includes a first lens component LC1 having negative refractive power and a biconcave lens L2, with the concave surface facing the image side. The second lens component LC2 having negative refractive power and the aspherical positive lens L3 having a biconvex lens shape, the third lens component LC3 having positive refractive power, the stop S, and the aspherical positive lens having a biconvex lens shape. The lens L4 includes a fourth lens component LC4 having a positive refractive power and a convex surface facing the image side. Further, a cover glass CG is disposed between the photographing lens SL2 and the image plane I. The cover glass CG is a parallel plane transmissive member, and the focal length does not vary depending on the presence or absence of the cover glass CG. However, since slight aberration variation occurs, the second embodiment is optimized to include the cover glass CG. Even if this cover glass CG is optically equivalently replaced with a color filter or a low-pass filter, or is divided or shared, there is no influence on the aberration.

  In the second embodiment, the object-side lens surface (fifth surface) of the aspherical positive lens L3 and the image-side lens surface (ninth surface) of the aspherical positive lens L4 are aspherical surfaces. The lens surfaces are used in pairs with a positional relationship that is symmetrical with respect to the stop S and contribute to further correction of coma.

  Table 3 below lists values of specifications of the photographing lens SL2 according to the second example. The surface numbers 1 to 11 shown in Table 3 correspond to the numbers 1 to 11 shown in FIG.

(Table 3)
[Overall specifications]
f = 1
FNO = 1.98
2ω = 160 degrees ymax = 1.12544


[Lens data]
m rd νd nd nP
1 11.20688 0.70418 46.579 1.8039970 1.7874850
2 2.54574 1.42997
3 -5.25816 0.63376 57.674 1.6273770 1.6164400
4 2.25258 1.02924
5 * 6.15347 2.46676 61.066 1.5900770 1.5801840
6 -2.96260 0.38730
7 0.00000 0.38730 Aperture S
8 4.37539 1.93773 51.234 1.7061580 1.6927140
9 * -3.73955 1.83717
10 0.00000 0.84501 64.119 1.5168000 1.4511770
11 0.00000 0.06875

[Aspherical data]
5th surface κ = -3.915602 A4 = -0.198396E-01 A6 = -0.198927E-03
A8 = -0.259502E-02 A10 = 0.631687E-03
9th surface κ = -24.610016 A4 = -0.410154E-01 A6 = 0.319899E-01
A8 = -0.140699E-01 A10 = 0.283445E-02

  Table 4 below shows the focal length and the condition corresponding value of the photographic lens SL2 according to the second example. Note that the condition-corresponding value for the conditional expression (6) is calculated from the refractive index with respect to the P-line of the medium of the aspherical positive lens L3 and the aspherical positive lens L4.

(Table 4)
f = 1.000
f1 = -4.338
f2 = -2.478
f3 = 3.827
f4 = 3.226
f12 = -1.281
f123 = 21.078
f34 = 2.454
(1) f1 / f2 = 1.750
(2) f4 / f = 3.226
(3) f3 / f4 = 1.186
(4) (r4 + r3) / (r4-r3) = − 0.4
(5) (r6 + r5) / (r6-r5) = − 0.350
(6) (n3 + n4) /2=1.636

  Thus, the photographic lens SL2 according to the second example satisfies all the conditional expressions (1) to (6).

  FIG. 4 shows various aberration diagrams of the spherical aberration, the field curvature, the distortion aberration, and the coma aberration of the photographing lens SL2 according to the second example. As is apparent from the aberration diagrams shown in FIG. 4, the photographic lens SL2 according to the second example has various aberrations corrected well and has high optical performance. The photographic lens SL2 according to the second embodiment is optimized in the near-infrared region having a center wavelength of 940 nm (P-line) and a wavelength range of ± 100 nm, but even with visible light having a center wavelength of 587.6 nm (d-line). Aberrations have been corrected.

[Third embodiment]
FIG. 5 is a diagram illustrating a configuration of the photographic lens SL3 according to the third example. The photographing lens SL3 is composed of a negative meniscus lens L1 having a concave surface directed toward the image side in order from the object side, and is composed of a first lens component LC1 having negative refractive power and a biconcave lens L2, with the concave surface facing the image side. The second lens component LC2 having negative refractive power and the aspherical positive lens L3 having a biconvex lens shape, the third lens component LC3 having positive refractive power, the stop S, and the aspherical positive lens having a biconvex lens shape. The lens L4 includes a fourth lens component LC4 having a positive refractive power and a convex surface facing the image side. Further, a cover glass CG is disposed between the photographing lens SL3 and the image plane I. The cover glass CG is a parallel plane transmissive member, and there is no fluctuation in the focal length depending on the presence or absence of the cover glass CG, but a slight aberration fluctuation occurs. Therefore, the third embodiment is optimized to include the cover glass CG. Even if this cover glass CG is optically equivalently replaced with a color filter or a low-pass filter, or is divided or shared, there is no influence on the aberration.

  In the third embodiment, the object-side lens surface (fifth surface) of the aspheric positive lens L3 and the image-side lens surface (ninth surface) of the aspheric positive lens L4 are aspheric surfaces. The lens surfaces are used in pairs with a positional relationship that is symmetrical with respect to the stop S and contribute to further correction of coma.

  Table 5 below lists values of specifications of the photographing lens SL3 according to the third example. The surface numbers 1 to 11 shown in Table 5 correspond to the numbers 1 to 11 shown in FIG.

(Table 5)
[Overall specifications]
f = 1
FNO = 1.8
2ω = 170 degrees ymax = 1.139

[Lens data]
m rd νd nd nP
1 13.46900 0.62937 46.601 1.8040000 1.7874850
2 2.59790 1.42724
3 -4.87325 0.62937 43.993 1.7667600 1.7502500
4 4.87325 1.91030
5 * 5.54964 2.01127 47.201 1.7740000 1.7582650
6 -4.11346 0.38461
7 0.00000 0.38461 Aperture S
8 14.97804 1.80503 40.499 1.8090000 1.7903450
9 * -3.38607 0.46767
10 0.00000 0.83916 67.817 1.4584400 1.4511770
11 0.00000 1.39946

[Aspherical data]
5th surface κ = -54.205082 A4 = 0.217021E-01 A6 = -0.212584E-01
A8 = 0.750408E-02 A10 = -0.125401E-02
9th surface κ = -0.312266 A4 = 0.126942E-01 A6 = -0.541059E-02
A8 = 0.566642E-02 A10 = -0.185804E-02

  Table 6 below shows the focal length and the condition corresponding value of the photographic lens SL3 according to the third example. Note that the condition-corresponding value for the conditional expression (6) is calculated from the refractive index with respect to the P-line of the medium of the aspherical positive lens L3 and the aspherical positive lens L4.

(Table 6)
f = 1.000
f1 = -4.194
f2 = -3.160
f3 = 3.423
f4 = 3.653
f12 = -1.494
f123 = 3.606
f34 = 2.545
(1) f1 / f2 = 1.327
(2) f4 / f = 3.653
(3) f3 / f4 = 0.9370
(4) (r4 + r3) / (r4-r3) = 0.000
(5) (r6 + r5) / (r6-r5) = − 0.149
(6) (n3 + n4) /2=1.774

  Thus, the photographic lens SL3 according to the third example satisfies all the conditional expressions (1) to (6) described above.

  FIG. 6 shows various aberration diagrams of spherical aberration, curvature of field, distortion, and coma aberration of the taking lens SL3 according to the third example. As is apparent from the respective aberration diagrams shown in FIG. 6, it can be seen that the photographic lens SL3 according to the third example has various aberrations corrected well and has high optical performance. The photographic lens SL3 according to the third embodiment is optimized in the near infrared region having a center wavelength of 940 nm (P-line) and a wavelength range of ± 100 nm. However, even with visible light having a center wavelength of 587.6 nm (d-line). Aberrations have been corrected.

[Fourth embodiment]
FIG. 7 is a diagram illustrating a configuration of the photographic lens SL4 according to the fourth example. The photographing lens SL4 is composed of a negative meniscus lens L1 having a concave surface facing the image side in order from the object side, and is composed of a first lens component LC1 having negative refractive power and a biconcave lens L2, with the concave surface facing the image side. The second lens component LC2 having negative refractive power and the aspherical positive lens L3 having a biconvex lens shape, the third lens component LC3 having positive refractive power, the stop S, and the aspherical positive lens having a biconvex lens shape. The lens L4 includes a fourth lens component LC4 having a positive refractive power and a convex surface facing the image side. Further, two members of an infrared cut filter FL and a cover glass CG are disposed between the photographing lens SL4 and the image plane I. The infrared cut filter FL and the cover glass CG are parallel plane transmission members, and the focal length does not vary depending on the presence or absence thereof, but slight aberration variations occur. Therefore, in the fourth embodiment, the cover glass CG is included. Optimized. Even if these infrared cut filter FL and cover glass CG are optically equivalently replaced with a color filter or a low-pass filter, or divided or combined, there is no effect on the aberration.

  In the fourth embodiment, the object-side lens surface (fifth surface) of the aspherical positive lens L3 and the image-side lens surface (ninth surface) of the aspherical positive lens L4 are aspherical surfaces. The lens surfaces are used in pairs with a positional relationship that is symmetrical with respect to the stop S and contribute to further correction of coma.

  Table 7 below lists values of specifications of the photographing lens SL4 according to the fourth example. The surface numbers 1 to 13 shown in Table 7 correspond to the numbers 1 to 13 shown in FIG.

(Table 7)
[Overall specifications]
f = 1
FNO = 1.9
2ω = 154 degrees ymax = 1.06

[Lens data]
m rd νd nd nP
1 18.75428 0.61878 46.576 1.8040000 1.7872350
2 2.57329 1.56070
3 -3.55273 0.61878 59.388 1.5831300 1.5732860
4 3.55273 1.71883
5 * 5.54984 1.85633 48.101 1.8066090 1.7904590
6 -4.04764 0.41252
7 0.00000 0.41252 Aperture S
8 6.29421 1.92509 59.382 1.5831300 1.5736580
9 * -2.96383 0.34377
10 0.00000 0.82504 64.103 1.5168000 1.5083920
11 0.00000 1.13048
12 0.00000 0.36095 67.817 1.4584400 1.4511770
13 0.00000 0.00000

[Aspherical data]
5th surface κ = 3.4336 A4 = -1.43108E-02 A6 = 5.61028E-04
A8 = -1.59606E-03 A10 = 5.21981E-04
9th surface κ = -17.153 A4 = -5.63230E-02 A6 = 4.66786E-02
A8 = -2.16207E-02 A10 = 4.62065E-03

  Table 8 below shows the focal length and the condition corresponding value of the photographic lens SL4 according to the fourth example. Note that the condition-corresponding value for the conditional expression (6) is calculated from the refractive index with respect to the P-line of the medium of the aspherical positive lens L3 and the aspherical positive lens L4.

(Table 8)
f = 1.000
f1 = -3.853
f2 = -3.003
f3 = 3.238
f4 = 3.801
f12 = -1.353
f123 = 3.433
f34 = 2.545
(1) f1 / f2 = 1.283
(2) f4 / f = 3.801
(3) f3 / f4 = 0.852
(4) (r4 + r3) / (r4-r3) = 0.000
(5) (r6 + r5) / (r6-r5) = − 0.157
(6) (n3 + n4) /2=1.682

  Thus, the photographic lens SL4 according to the fourth example satisfies all the conditional expressions (1) to (6).

  FIG. 8 shows various aberration diagrams of spherical aberration, curvature of field, distortion, and coma aberration of the taking lens SL4 according to the fourth example. As is apparent from the respective aberration diagrams shown in FIG. 8, it can be seen that the photographic lens SL4 according to the fourth example has various aberrations corrected well and has high optical performance. The photographic lens SL4 according to the fourth example is optimized in the near infrared region having a center wavelength of 940 nm (P-line) and a wavelength range of ± 100 nm. However, even with visible light having a center wavelength of 587.6 nm (d-line). Aberrations have been corrected.

[Fifth embodiment]
FIG. 9 is a diagram illustrating a configuration of the photographic lens SL5 according to the fifth example. The photographing lens SL3 is composed of a negative meniscus lens L1 having a concave surface directed toward the image side in order from the object side, and is composed of a first lens component LC1 having negative refractive power and a biconcave lens L2, with the concave surface facing the image side. The second lens component LC2 having negative refractive power and the aspherical positive lens L3 having a biconvex lens shape, the third lens component LC3 having positive refractive power, the stop S, and the aspherical positive lens having a biconvex lens shape. The lens L4 includes a fourth lens component LC4 having a positive refractive power and a convex surface facing the image side. Further, a cover glass CG is disposed between the photographing lens SL5 and the image plane I. The cover glass CG is a parallel plane transmissive member, and there is no fluctuation in the focal length depending on the presence or absence of the cover glass CG. However, since slight aberration fluctuation occurs, the fifth embodiment is optimized including the cover glass CG. Even if this cover glass CG is optically equivalently replaced with a color filter or a low-pass filter, or is divided or shared, there is no influence on the aberration.

  In the fifth embodiment, the object-side lens surface (fifth surface) of the aspherical positive lens L3 and the image-side lens surface (ninth surface) of the aspherical positive lens L4 are aspherical surfaces. The lens surfaces are used in pairs with a positional relationship that is symmetrical with respect to the stop S and contribute to further correction of coma.

  Table 9 below provides values of specifications of the photographing lens SL5 according to the fifth example. The surface numbers 1 to 11 shown in Table 5 correspond to the numbers 1 to 11 shown in FIG.

(Table 9)
[Overall specifications]
f = 1
FNO = 1.9
2ω = 156 degrees ymax = 1.1

[Lens data]
m rd νd nd nP
1 13.48691 0.62937 46.601 1.8040000 1.7874850
2 2.59790 1.45777
3 -4.83119 0.62937 53.200 1.6940000 1.6811580
4 4.83119 1.76934
5 * 13.21178 2.00104 47.201 1.7740000 1.7582650
6 -3.00902 0.48776
7 0.00000 0.48776 Aperture S
8 23.63308 1.81730 40.499 1.8090000 1.7903450
9 * -3.26043 0.46766
10 0.00000 0.58682 67.817 1.4584400 1.4511770
11 0.00000 1.57336

[Aspherical data]
5th surface κ = -347.46757 A4 = -0.566711E-2 A6 = -0.107324E-01
A8 = 0.229848E-2 A10 = -0.207130E-03
9th surface κ = 1.702697 A4 = 0.177798E-01 A6 = -0.23277E-02
A8 = 0.348462E-02 A10 = -0.952961E-03

  Table 10 below shows the focal length and the condition corresponding value of the photographic lens SL5 according to the fifth example. Note that the condition-corresponding value for the conditional expression (6) is calculated from the refractive index with respect to the P-line of the medium of the aspherical positive lens L3 and the aspherical positive lens L4.

(Table 10)
f = 1.000
f1 = -4.193
f2 = -3.455
f3 = 3.414
f4 = 3.737
f12 = -1.574
f123 = 3.209
f34 = 2.535
(1) f1 / f2 = 1.214
(2) f4 / f = 3.737
(3) f3 / f4 = 0.914
(4) (r4 + r3) / (r4-r3) = 0.000
(5) (r6 + r5) / (r6-r5) = − 0.629
(6) (n3 + n4) /2=1.774

  Thus, the photographic lens SL5 according to the fifth example satisfies all the conditional expressions (1) to (6).

  FIG. 10 shows various aberration diagrams of spherical aberration, curvature of field, distortion, and coma of the taking lens SL5 according to the fifth example. As is apparent from the respective aberration diagrams shown in FIG. 10, it can be seen that the photographic lens SL5 according to the fifth example has various aberrations corrected well and has high optical performance. The photographic lens SL5 according to the fifth example is optimized in the near infrared region having a center wavelength of 940 nm (P line) and a wavelength range of ± 100 nm. However, even with visible light having a center wavelength of 587.6 nm (d line). Aberrations have been corrected.

[Sixth embodiment]
FIG. 11 is a diagram illustrating a configuration of the photographic lens SL6 according to the sixth example. This photographic lens SL6 is an example in which a protective member PG having a negative meniscus lens shape is disposed on the object side of the photographic lens SL4 of the fourth example. This protective member PG combines the purpose of protecting the internal lens or camera and the effect of maintaining a good appearance. After the photographing lens SL6 is adjusted and inspected alone without attaching the protective member PG, the protective member PG is attached. However, it is designed to maintain the performance without changing the aberration and focal length.

  The photographic lens SL6 according to the sixth example includes, in order from the object side, a negative meniscus lens L1 having a concave surface directed toward the image side, a first lens component LC1 having negative refractive power, and a biconcave lens L2. The second lens component LC2 having a negative refractive power with the concave surface facing the image side, the aspherical positive lens L3 having a biconvex lens shape, a third lens component LC3 having a positive refractive power, a stop S, The lens includes a convex aspherical positive lens L4, and a fourth lens component LC4 having a positive refractive power and a convex surface facing the image side. Further, on the object side of the photographing lens SL6, a protective member PG made of a negative meniscus aspheric negative lens having a convex surface facing the object side is disposed. Are arranged with two members, an infrared cut filter FL and a cover glass CG. The infrared cut filter FL and the cover glass CG are transmissive members having parallel planes, and the focal length does not vary depending on the presence or absence thereof, but slight aberration variations occur. Therefore, in the sixth embodiment, the cover glass CG is included. Optimized. Even if these infrared cut filter FL and cover glass CG are optically equivalently replaced with a color filter or a low-pass filter, or divided or combined, there is no effect on the aberration.

  In the sixth embodiment, the object-side lens surface (seventh surface) of the aspherical positive lens L3 and the image-side lens surface (eleventh surface) of the aspherical positive lens L4 are aspherical surfaces. The lens surfaces are used in pairs with a positional relationship that is symmetrical with respect to the stop S and contribute to further correction of coma. The object-side and image-side lens surfaces (first surface and second surface) of the protective member PG are also aspherical surfaces.

  Table 11 below provides values of specifications of the photographing lens SL6 according to the sixth example. The surface numbers 1 to 15 shown in Table 11 correspond to the numbers 1 to 15 shown in FIG.

(Table 11)
[Overall specifications]
f = 1
FNO = 1.9
2ω = 152 degrees ymax = 1.1

[Lens data]
m rd νd nd nP
1 * 101.00000 0.80000 55.732 1.5311300 1.5220340
2 * 87.00000 1.00000
3 18.75428 0.61878 46.576 1.8040000 1.7872350
4 2.57329 1.56070
5 -3.55273 0.61878 59.388 1.5831300 1.5732860
6 3.55273 1.71883
7 * 5.54984 1.85633 48.101 1.8066090 1.7904590
8 -4.04764 0.41252
9 0.00000 0.41252 Aperture S
10 6.29421 1.92509 59.382 1.5831300 1.5736580
11 * -2.96383 0.34377
12 0.00000 0.82504 64.103 1.5168000 1.5083920
13 0.00000 1.13048
14 0.00000 0.36095 67.817 1.4584400 1.4511770
15 0.00000 0.00000

[Aspherical data]
1st surface κ = 0.000 A4 = 2.43056e-04 A6 = -1.35170e-06
A8 = 2.23332e-08 A10 = 6.42214e-11
2nd surface κ ＝ 0.0000 A4 ＝ 2.31722e-04 A6 ＝ 1.94247e-06
A8 = -2.29869e-08 A10 = 1.15475e-10
7th surface κ = 3.4336 A4 = -1.43108E-02 A6 = 5.61028E-04
A8 = -1.59606E-03 A10 = 5.21981E-04
11th surface κ = -17.153 A4 = -5.63230E-02 A6 = 4.66786E-02
A8 = -2.16207E-02 A10 = 4.62065E-03

  Table 12 below shows the focal length and the condition corresponding value of the photographic lens SL6 according to the sixth example. Note that the condition-corresponding value for the conditional expression (6) is calculated from the refractive index with respect to the P-line of the medium of the aspherical positive lens L3 and the aspherical positive lens L4.

(Table 12)
f = 1.000
f1 = -3.853
f2 = -3.003
f3 = 3.238
f4 = 3.801
f12 = -1.353
f123 = 3.433
f34 = 2.545
(1) f1 / f2 = 1.283
(2) f4 / f = 3.801
(3) f3 / f4 = 0.852
(4) (r4 + r3) / (r4-r3) = 0.000
(5) (r6 + r5) / (r6-r5) = − 0.157
(6) (n3 + n4) /2=1.682

  Thus, the photographic lens SL6 according to the sixth example satisfies all the conditional expressions (1) to (6) described above.

  FIG. 12 shows various aberrations of spherical aberration, curvature of field, distortion, and coma aberration of the taking lens SL6 according to the sixth example. As is apparent from the aberration diagrams shown in FIG. 12, the photographic lens SL6 according to the sixth example has various aberrations corrected well, and has high optical performance. The photographic lens SL6 according to the sixth example is optimized in the near-infrared region having a center wavelength of 940 nm (P line) and a wavelength range of ± 100 nm. Aberrations have been corrected.

[Seventh embodiment]
FIG. 13 is a diagram illustrating a configuration of a photographic lens SL7 according to the seventh example. The photographing lens SL7 is composed of a negative meniscus lens L1 having a concave surface facing the image side in order from the object side, and is composed of a first lens component LC1 having negative refractive power and a biconcave lens L2, with the concave surface facing the image side. The second lens component LC2 having negative refractive power and the aspherical positive lens L3 having a biconvex lens shape, the third lens component LC3 having positive refractive power, the stop S, and the aspherical positive lens having a biconvex lens shape. The lens L4 includes a fourth lens component LC4 having a positive refractive power and a convex surface facing the image side. Further, a plane-convex lens L5 having a convex surface directed toward the object side is provided between the photographing lens SL7 and the image plane I, and has a positive refractive power and functions to adjust the exit pupil position of the photographing lens SL7. The fifth lens component LC5 and three members of the infrared cut filter FL and the cover glass CG are arranged. The infrared cut filter FL and the cover glass CG are parallel plane transmission members, and the focal length does not vary depending on the presence or absence thereof, and some aberration variation occurs. Since the meniscus concave lens on the object side of the photographic lens SL7 and the positive lens L5 on the image side of the photographic lens SL7 have slight focal length fluctuations and aberration fluctuations, this seventh embodiment is optimized for the entire system. is there. Even if these infrared cut filter FL and cover glass CG are optically equivalently replaced with a color filter or a low-pass filter, or divided or combined, there is no effect on the aberration.

  Further, as described in the sixth embodiment, a protective member having both the purpose of protecting the internal lens or the camera and the effect of maintaining a good appearance is disposed on the photographing lens SL7 according to the seventh embodiment. A protective member PG, which is an aspheric negative lens having a negative meniscus lens shape with a convex surface facing the object side, is disposed on the object side of the taking lens SL7 shown in FIG.

  In the seventh embodiment, the object-side lens surface (seventh surface) of the aspherical positive lens L3 and the image-side lens surface (eleventh surface) of the aspherical positive lens L4 are aspherical surfaces. The lens surfaces are used in pairs with a positional relationship that is symmetrical with respect to the stop S and contribute to further correction of coma. The object-side and image-side lens surfaces (first surface and second surface) of the protective member PG are also aspherical surfaces.

  Table 13 below provides values of specifications of the photographing lens SL7 according to the seventh example. The surface numbers 1 to 15 shown in Table 13 correspond to the numbers 1 to 15 shown in FIG.

(Table 13)
[Overall specifications]
f = 1
FNO = 2.0
2ω = 164 degrees ymax = 1.13

[Lens data]
m rd νd nd nP
1 * 61.61542 0.42771 55.727 1.5311300 1.5216360
2 * 53.30161 0.61676
3 10.66932 0.61005 43.983 1.8085420 1.7911310
4 2.20770 1.37711
5 -3.90659 0.61005 40.499 1.8090000 1.7903450
6 3.90659 1.03410
7 * 6.10054 1.80959 24.100 1.8210000 1.7916920
8 -4.08192 0.33553
9 0.00000 0.33553 Aperture S
10 14.16615 1.76917 53.200 1.6940000 1.6811580
11 * -3.15598 0.12201
12 9.38023 1.31847 46.601 1.8040000 1.7874850
13 0.00000 0.18302
14 0.00000 0.61005 29.897 1.5830000 1.5660830
15 0.00000 1.37361

[Aspherical data]
1st surface κ ＝ 0.0000 A4 ＝ -8.23070e-05 A6 ＝ 1.65707e-07
A8 = 7.11465e-09 A10 = 0.00000e + 00
Second side κ ＝ 0.0000 A4 ＝ －9.54698e-05 A6 ＝ －6.31119e-09
A8 = 1.16667e-08 A10 = 0.000000 + 00
7th surface κ = -5.4058 A4 = -1.15583e-02 A6 = -1.91113e-03
A8 = -1.69304e-03 A10 = 6.63133e-04
11th surface κ = -1.9006 A4 = 6.82071e-03 A6 = -6.17520e-03
A8 = 4.01650e-03 A10 = -8.60219e-04

  Table 14 below shows the focal length and the condition corresponding value of the photographic lens SL7 according to the seventh example. Note that the condition-corresponding value for the conditional expression (6) is calculated from the refractive index with respect to the P-line of the medium of the aspherical positive lens L3 and the aspherical positive lens L4.

(Table 14)
f = 1.000
f1 = -3.634
f2 = -2.389
f3 = 3.352
f4 = 3.953
f12 = -1.162
f123 = 30.299
f34 = 2.502
(1) f1 / f2 = 1.521
(2) f4 / f = 3.953
(3) f3 / f4 = 0.848
(4) (r4 + r3) / (r4-r3) = 0.000
(5) (r6 + r5) / (r6-r5) = − 0.198
(6) (n3 + n4) /2=1.636

  Thus, the photographic lens SL7 according to the seventh example satisfies all the conditional expressions (1) to (6) described above.

  FIG. 14 shows various aberrations of spherical aberration, curvature of field, distortion, and coma of the taking lens SL7 according to the seventh example. As is apparent from the respective aberration diagrams shown in FIG. 14, it can be seen that the photographic lens SL7 according to the seventh example has various aberrations corrected well and has high optical performance. The photographic lens SL7 according to the seventh example is optimized in the near infrared region having a center wavelength of 940 nm (P line) and a wavelength range of ± 100 nm. Aberrations have been corrected.

  As described above, the values of the specifications in the first to seventh embodiments satisfy all the conditional expressions described above. However, for at least one conditional expression, the numerical value ranges of the upper limit value and the lower limit value of all the examples are as follows. As long as the numerical range is expanded by ± 10%, further excellent aberration correction can be achieved, which is more desirable. If only the numerical range expanded by ± 5% is allowed in the numerical ranges of the upper limit value and the lower limit value in all the examples, further better aberration correction can be achieved, and it is even more desirable.

DESCRIPTION OF SYMBOLS 10 In-vehicle observation apparatus (imaging apparatus) SL (SL1-SL7) Shooting lens LC1 1st lens component LC2 2nd lens component LC3 3rd lens component LC4 4th lens component S Aperture

Claims (7)

From the object side,
A first lens component having a negative meniscus lens shape with a concave surface facing the image side and having negative refractive power;
A second lens component having a negative refractive power with a concave surface facing the image side;
A third lens component having a biconvex lens shape and having a positive refractive power;
A fourth lens component having a convex surface facing the image side and having a positive refractive power,
All lens components are single lenses,
A photographic lens characterized by satisfying the following formula.
1.0 <f1 / f2 <2.6
2.9 <f4 / f <4.2
-1.15 <(r4 + r3) / (r4-r3) <0.2
−0.7 <(r6 + r5) / (r6-r5) <− 0.07
However,
f: focal length of the entire system f1: focal length of the first lens component f2: focal length of the second lens component f4: focal length of the fourth lens component r3: lens closest to the object side of the second lens component Radius of curvature of surface r4: radius of curvature of the lens surface closest to the image side of the second lens component
r5: radius of curvature of the lens surface closest to the object side of the third lens component
r6: radius of curvature of the lens surface closest to the image side of the third lens component The photographic lens according to claim 1, wherein a condition of the following formula is satisfied.
0.78 <f3 / f4 <1.30
However,
f3: focal length of the third lens component Photographing lens according to claim 1 or 2, characterized in that the following conditional expression is satisfied:.
1.61 <(n3 + n4) / 2 <1.82
However,
n3: the third lens component of the medium P line (lambda = 940 nm) refractive index for n4: refractive index for the fourth lens component of the medium P line (lambda = 940 nm) Photographing lens according to claim 1, characterized in that it comprises a stop between said third lens component and the fourth lens component. The photographic lens according to any one of claims 1 to 4, wherein a maximum angle of view of light rays contributing to image formation is 120 degrees or more. 6. The photographic lens according to claim 1, wherein the photographic lens has negative distortion. Imaging apparatus characterized by having a taking lens according to any one of claims 1 to 6.

Images