Imaging lens and imaging apparatus

Abstract

To provide a single focus lens which is excellent in optical characteristics and advantageous in reduction in size and cost.SOLUTION: An imaging lens has seven to nine lenses including a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, and a final lens arranged closest to the image side and having negative refractive power, arranged in order from the object side, and a diaphragm and has specific optical characteristics represented by a specific expression.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an imaging lens and an imaging device. [Background technology]

[0002] In recent years, development of lens imaging devices has been promoted for use in vehicle-mounted lenses, surveillance or factory automation single focus lenses, and imaging optical systems for digital input / output devices such as passenger surveillance. Under these circumstances, single focus lenses of various configurations have been considered, and for example, single focus lenses including resin lenses have been considered from the viewpoint of cost reduction. As such single focus lenses, single focus lenses consisting of seven lenses including resin lenses are known (for example, see Patent Documents 1 to 6). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-102211 A [Patent Document 2] JP 2022-110784 A [Patent Document 3] China Patent Application Publication No. 113204099 [Patent Document 4] China Patent Application Publication No. 116149031 [Patent Document 5] JP 2017-125887 A [Patent Document 6] Special Publication No. 2018-523150 Summary of the Invention [Problem to be solved by the invention]

[0004] However, a single focal length lens is required to meet various conditions in addition to optical characteristics depending on its application. The conventional single focal length lenses described above have yet to be studied in order to realize excellent temperature compensation, reduce costs, and achieve compactness.

[0005] An object of one embodiment of the present invention is to provide a single focal length lens and an imaging device that have excellent optical characteristics and are advantageous in terms of size and cost reduction. [Means for solving the problem]

[0006] In order to solve the above problems, an imaging lens according to one aspect of the present invention comprises: An imaging lens having seven to nine lenses including, in order from an object side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, and a final lens which is disposed closest to an image plane and has negative refractive power, and an aperture, a resin lens set is provided on the object side and the image plane side of the aperture, The resin lens set includes a resin lens having a positive refractive power and a resin lens having a negative refractive power, the resin lens set being adjacent to each other, One of the resin lenses included in the resin lens set has a refractive index at d line that is smaller than 1.68 and an Abbe number that is greater than 20 and less than 30; and The following formula is satisfied: -0.50 <f×Φ2pf<0.42···(1) 0.0 <f×Φ2pb<0.7···(2) however, f: focal length of the optical system of the imaging lens Φ2pf: the reciprocal of the composite focal length of the two plastic lenses constituting the plastic lens set located closer to the object than the aperture Φ2pb: the reciprocal of the composite focal length of the two plastic lenses constituting the plastic lens set located on the image side of the aperture

[0007] In order to solve the above-mentioned problem, an imaging device according to one aspect of the present invention includes the imaging lens and an imaging element on the image plane side of the imaging lens that converts an optical image formed by the imaging lens into an electrical signal. Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to provide a single focal length lens and an imaging device that have excellent optical characteristics and are advantageous in terms of size and cost reduction. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an optical configuration of the imaging lens of Example 1 when focused at 700 mm. FIG. [Diagram 2] 3A to 3C are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens of Example 1. [Diagram 3] 11 is a diagram illustrating an optical configuration of the imaging lens of Example 2 when focused at 700 mm. FIG. [Figure 4] 10A to 10C are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens of Example 2. [Diagram 5] FIG. 11 is a diagram illustrating an optical configuration of the imaging lens of Example 3 when focused at 700 mm. [Figure 6] 11A to 11C are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens of Example 3. [Figure 7] FIG. 13 is a diagram illustrating an optical configuration of the imaging lens of Example 4 when focused at 700 mm. [Figure 8] 10A to 10C are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens of Example 4. [Figure 9] FIG. 13 is a diagram illustrating an optical configuration of the imaging lens of Example 5 when focused at 700 mm. [Figure 10] 13A to 13C are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens of Example 5. [Figure 11] FIG. 23 is a diagram illustrating an optical configuration of the imaging lens of Example 6 when focused at 700 mm. [Figure 12] 13A to 13C are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens of Example 6. [Figure 13] 1 is a diagram illustrating an example of a configuration of an imaging device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of an imaging lens and an imaging device according to the present invention will be described. More specifically, this embodiment relates to an imaging lens and an imaging device suitable for an imaging device using a solid-state imaging element (CCD, CMOS, etc.) such as a digital still camera or a digital video camera. However, the imaging lens and imaging device described below are one aspect of the imaging lens and imaging device according to the present invention, and the imaging lens and imaging device according to the present invention are not limited to the following aspects.

[0011] 1. Imaging lens 1-1.Optical configuration The optical configuration of an imaging lens according to one embodiment of the present invention will be described. The imaging lens of this embodiment has seven to nine lenses, including a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, and a final lens arranged closest to the image surface side and having negative refractive power, arranged in this order from the object side, and an aperture. The imaging lens has independent resin lens sets on the object side and the image surface side of the aperture. It is preferable that the imaging lens has a resin lens set from the viewpoint of cost reduction by including a resin lens.

[0012] The imaging lens according to this embodiment includes seven or more lenses. This configuration is preferable from the viewpoint of further improving the optical characteristics of the imaging lens. On the other hand, the number of lenses included in the imaging lens is nine or less, and may be eight or less. This configuration is preferable from the viewpoint of reducing the number of constituent lenses and reducing costs and variations during assembly.

[0013] (1) Plastic lens set The resin lens set is composed of a resin lens having a positive refractive power and a resin lens having a negative refractive power, which are adjacent to each other. This configuration is preferable from the viewpoint of achieving excellent optical characteristics. For example, it is preferable from the viewpoint of temperature correction. In this specification, "temperature correction" refers to correction for suppressing the variation of resolution due to temperature, for example, correction for keeping the resolution constant at temperatures of -40°C or more and 120°C or less.

[0014] The resin lens set is composed of only a resin lens having a substantially positive refractive power and a resin lens having a negative refractive power, and does not include other lenses, but may include an optical element having no substantial refractive power. In the resin lens set on the object side of the aperture, for example, a lens having a positive refractive power and a lens having a negative refractive power are arranged in order from the object side. In addition, in the resin lens set on the image surface side of the aperture, for example, a lens having a negative refractive power and a lens having a positive refractive power are arranged in order from the object side. The resin lens sets only need to be independently arranged on the object side and the image surface side of the aperture, and there is no particular limitation on the position of the imaging lens where each resin lens set is arranged.

[0015] One of the resin lenses included in the resin lens set has a refractive index at the d-line that is smaller than 1.68, and has an Abbe number that is greater than 20 and less than 30. This configuration is preferable from the viewpoints of large dispersion and simultaneously satisfying chromatic aberration correction and temperature correction.

[0016] The two resin lenses constituting the resin lens set are preferably not cemented. This configuration is preferable from the viewpoint of improving the desired optical characteristics, particularly various aberrations, because the surface shapes of the two non-cemented surfaces are more likely to exhibit their effects, and from the viewpoint of preventing peeling of the cementing material when the two resin lenses are cemented together.

[0017] In this specification, the term "optical system of an imaging lens" refers to an optical system including optical elements from the lens closest to the object to the lens closest to the image surface. The optical system of an imaging lens may further include optical elements outside the above range, and may or may not include an optical element that blocks light of a specific wavelength, such as a cover glass of an imaging element or an infrared cut filter.

[0018] Hereinafter, in the imaging lens, a set of lenses closer to the object side than the aperture is referred to as the first lens group, and a set of lenses closer to the image surface side than the aperture is referred to as the second lens group. The imaging lens does not include any lens group other than the lens group included in the first lens group or the second lens group, but may include an optical element that does not have substantial refractive power.

[0019] (2) First lens group The first lens group preferably has at least three lenses, that is, the first lens group may have, in order from the object side, at least a first lens, a second lens, and a third lens.

[0020] The first lens has a negative refractive power. In this configuration, it is preferable that the first lens has a negative refractive power from the viewpoint of widening the angle and reducing the diameter of the front lens. In this specification, "wide angle" refers to a lens with a horizontal angle of view of approximately 120° or more. Also, "front lens" refers to the lens of the imaging lens that is disposed closest to the object.

[0021] The shape of the first lens is not particularly limited and can be changed as appropriate to obtain the desired optical characteristics. It is preferable that the first lens has a concave surface on the image side. This configuration is preferable from the viewpoint of appropriately correcting the curvature of field and the image surface difference associated with a wide angle.

[0022] The second lens has negative refractive power. That is, in this imaging lens, both the first lens and the second lens have negative refractive power. This configuration is preferable from the viewpoint of widening the angle of the imaging lens, because it can appropriately maintain distortion and curvature of field.

[0023] It is preferable that the second lens has a meniscus shape and a concave surface on the image side, which is preferable from the viewpoint of appropriately correcting the curvature of field and the image surface difference that accompanies a wide angle.

[0024] The third lens has a positive refractive power. This configuration is preferable from the viewpoint of appropriately correcting chromatic aberration and distortion, because it makes it possible to correct coma generated in the first lens and the second lens.

[0025] It is preferable that the third lens has a convex surface facing the image plane side. This configuration is preferable from the viewpoint of appropriately correcting coma aberration occurring in the first lens and the second lens.

[0026] It is preferable that the lenses included in the first lens group are not cemented together. That is, it is preferable that the lenses included in the first lens group are all independent lenses. The first lens group is a particularly important configuration for realizing a wide angle and suppressing distortion aberration and lateral chromatic aberration. Therefore, by not cementing the lenses included in the first lens group together, it is easier to achieve the effect of correcting various aberrations due to the surface shape of each lens, and the degree of freedom in design is also improved, so it is preferable from the viewpoint of optimizing the optical system to achieve desired optical characteristics. In addition, this configuration is also preferable from the viewpoint of preventing peeling of the bonding adhesive when the temperature changes.

[0027] It is preferable that the first lens group includes two resin lenses. In other words, it is preferable that the first lens group is composed of glass lenses other than the resin lens set. This configuration is preferable from the viewpoint of suppressing the influence of yellowing caused by the resin lenses, since the total thickness of the resin lenses is not too thick. This configuration is also preferable from the viewpoint of temperature correction in the first lens group.

[0028] (3) Second lens group The second lens group includes a final lens. By providing the imaging lens with the second lens group, astigmatism generated in the first lens group can be corrected, which is advantageous for achieving a wider angle.

[0029] The final lens has negative refractive power. This configuration is preferable from the viewpoint of improving distortion correction. Furthermore, in the optical system of the imaging lens, it is preferable that all lenses before the final lens are arranged to have positive refractive power, and the optical system as a whole has a positive-negative telephoto configuration. This configuration is preferable from the viewpoint of shortening the optical system of the imaging lens.

[0030] It is preferable that the final lens has a convex surface on the image surface side. This configuration is preferable from the viewpoint of appropriately correcting the curvature of field and the image surface difference. It is more preferable that the final lens has a meniscus shape and has a convex surface on the image surface side. This configuration is preferable from the viewpoint of appropriately correcting the distortion and the curvature of field and from the viewpoint of shortening the overall length of the optical system.

[0031] It is preferable that the second lens group has at least two lenses having positive refractive power, from the viewpoint of appropriately correcting curvature of field.

[0032] It is preferable that the lens closest to the object side in the second lens group has a positive refractive power. Hereinafter, this lens may be referred to as lens L21. This configuration is advantageous for achieving high resolution at peripheral image heights and a wide angle imaging lens, since the distortion and astigmatism generated in the first lens group can be appropriately corrected by the second lens group.

[0033] The object-side surface of lens L21 is preferably a convex surface with a value r / f, obtained by dividing the radius of curvature r by the focal length f of the optical system of the imaging lens, of 15 or less, and more preferably a convex surface with r / f of 10 or less. A larger curvature for the object-side surface of the lens in the second lens group is preferable, as this is more advantageous for achieving high resolution at peripheral image heights and a wide angle of the imaging lens.

[0034] It is preferable that both surfaces of the lens L21 are convex. By having both surfaces of the lens be convex, when the lens has a strong power, it is possible to divide the power between the object side surface and the image side surface, and therefore the aberration correction can be divided by two surfaces. Since dividing the aberration correction makes it possible to alleviate abrupt light refraction, this configuration is preferable from the viewpoint of suppressing the occurrence of high-order aberrations.

[0035] In the lens L21, from the viewpoint of appropriately correcting chromatic aberration, it is preferable that the lens L21 is a low dispersion glass lens. Since the lens L21 has a large difference in the incident angle characteristics between off-axis light rays and on-axis light rays, the effect of correcting off-axis chromatic aberration is higher than that of on-axis chromatic aberration. In particular, the Abbe number at the d-line is preferably larger than 45, and more preferably larger than 48. From the viewpoint of appropriately correcting chromatic aberration, it is preferable that the Abbe number at the d-line is not below the lower limit, and the larger the Abbe number, the greater this effect becomes.

[0036] Of the two lenses having positive refractive power that the second lens group may include, the shape, material, etc. of the lens Lp2 other than L21 are not particularly limited and can be changed as appropriate from the viewpoint of achieving desired optical characteristics.

[0037] In the second lens group, a lens having negative refractive power may be disposed on the object side of all lenses having positive refractive power except L21, or a lens having negative refractive power may be disposed on the object side of at least one of the lenses having positive refractive power except L21. This configuration makes it easier to position the entrance pupil of the second lens group closer to the object side, and is therefore preferable from the viewpoints of radial compactness and appropriate correction of axial and near-axial chromatic aberration.

[0038] It is preferable that the second lens group has at least one lens having negative refractive power in addition to the final lens, from the viewpoint of appropriately correcting chromatic aberration.

[0039] The lens having negative refractive power included in the second lens group preferably has a refractive index at the d-line of more than 1.65, more preferably more than 1.75. From the viewpoint of miniaturization of the imaging lens, it is preferable that the refractive index does not fall below the lower limit.

[0040] In addition, it is preferable to dispose a lens having positive refractive power on the object side of the lens having negative refractive power in the second lens group. This configuration is preferable from the viewpoint of appropriately correcting axial and near-axial chromatic aberration. In particular, it is preferable to dispose a lens having positive refractive power on the object side of the final lens from the viewpoint of obtaining this effect.

[0041] It is preferable that the second lens group has a positive refractive power as a whole. This configuration is preferable from the viewpoint of correcting astigmatism generated in the first lens group. This configuration is also preferable from the viewpoint of realizing a bright imaging lens.

[0042] It is preferable that the lenses included in the second lens group are not cemented together. In other words, it is preferable that all the lenses included in the second lens group are independent lenses. By not cementing the lenses included in the second lens group together, the effect of the surface shape of each lens can be easily exhibited, and the degree of freedom in design is also improved, which is preferable from the viewpoint of optimizing the optical system to achieve desired optical characteristics. It is also preferable from the viewpoint of preventing peeling of the bonding adhesive when the temperature changes.

[0043] The second lens group preferably contains two resin lenses. In other words, the second lens group is preferably composed of glass lenses other than the resin lens set. This configuration is preferable from the viewpoint of suppressing the influence of yellowing of the resin, since the total thickness of the resin lenses is not too thick. This configuration is also preferable from the viewpoint of temperature correction in the first lens group.

[0044] (3) Squeeze The diaphragm is located closer to the image plane than the third lens and closer to the object than the final lens. The diaphragm determines the F-number of the imaging lens. In this specification, the "diaphragm" is also called the "aperture diaphragm."

[0045] It is preferable that lenses having positive refractive power are arranged on both the object side and the image side of the aperture. This configuration is preferable from the viewpoint of reducing the effective diameter of both lenses on either side of the aperture. It is also possible to make both the object side of the object side positive lens and the image side of the image side positive lens smaller than the aperture surface. This is advantageous in suppressing the effect of mutual aberration correction between adjacent lenses.

[0046] (4)Other The imaging lens preferably has a chief ray axis angle (Cra) in the range of 25° or less. Here, the chief ray axis angle is the angle of the chief ray that enters the image plane from the imaging lens. This configuration is preferable from the viewpoint of achieving both a compact imaging lens and sensitivity in the imaging element.

[0047] 1-2.Formula It is desirable for the imaging lens to employ the above-mentioned configuration and to satisfy at least one of the following expressions.

[0048] 1-2-1.Formula (1) -0.50 <f×Φ2pf<0.42···(1) f: focal length of the imaging lens optical system Φ2pf: The reciprocal of the composite focal length of the two plastic lenses that make up the plastic lens set on the object side of the aperture

[0049] Formula (1) is a formula for appropriately defining the ratio between the focal length of the optical system of the imaging lens and the composite focal length of two plastic lenses constituting the plastic lens set on the object side of the aperture. Here, Φ2pf represents the composite power of the plastic lens set on the object side of the aperture. It is preferable to satisfy formula (1) from the viewpoint of reducing the focal length of the optical system of the imaging lens and suppressing the variation of the chief ray and the angle of view due to temperature.

[0050] From the viewpoint of shortening the focal length of the optical system of the imaging lens and suppressing the change in the focal position due to temperature change with respect to the physical image surface (surface of the imaging element), f×Φ2pf is preferably -0.35 or more, more preferably -0.32 or more, and even more preferably -0.28 or more. Also, from the viewpoint of shortening the focal length of the optical system of the imaging lens and suppressing the change in the chief ray and the change in the angle of view due to temperature, f×Φ2pf is preferably 0.40 or less, and more preferably 0.20 or less. The closer to 0 f×Φ2pf is, the more preferable it is.

[0051] 1-2-2.Formula (2) 0.0 <f×Φ2pb<0.7···(2) f: focal length of the imaging lens optical system Φ2pb: The reciprocal of the composite focal length of the two plastic lenses that make up the plastic lens set on the image side of the aperture

[0052] Equation (2) is an equation for appropriately defining the ratio between the focal length of the optical system of the imaging lens and the composite focal length of the two resin lenses constituting the resin lens set on the image side of the aperture. Here, Φ2pb represents the composite power of the resin lens set on the image side of the aperture. Satisfying equation (2) is preferable from the viewpoint of reducing the focal length of the optical system of the imaging lens and thus reducing the change in the focus position due to temperature change on the sensor surface. Here, the sensor surface refers to the physical image surface (for example, the surface of the imaging element).

[0053] From the viewpoint of shortening the focal length of the imaging lens of the optical system of the imaging lens and suppressing the change in the focal position due to the temperature change with respect to the physical image surface (surface of the imaging element), f×Φ2pb is preferably 0.03 or more, and more preferably 0.04 or more. Also, from the viewpoint of shortening the focal length of the imaging lens of the optical system and suppressing the change in the chief ray and the change in the angle of view due to the temperature, f×Φ2pb is preferably 0.6 or less, more preferably 0.55 or less, and even more preferably 0.47 or less.

[0054] 1-2-3.Formula (3) -2.3 <f2 / f<0.0···(3) f: focal length of the imaging lens optical system f2: focal length of second lens

[0055] Formula (3) is a formula for appropriately defining the ratio between the focal length of the optical system of the imaging lens and the focal length of the second lens. Satisfying formula (3) is preferable from the viewpoints of appropriately maintaining distortion and curvature of field, achieving a wide angle, and improving and maintaining resolution performance.

[0056] From the viewpoints of shortening the focal length of the optical system of the imaging lens, maintaining a wide angle, and improving and maintaining the resolution performance, f2 / f is preferably -2.0 or more, and more preferably -1.9 or more. Also, from the viewpoints of keeping distortion and curvature of field appropriate, f2 / f is preferably -0.80 or less, and more preferably -0.50 or less.

[0057] 1-2-4.Formula (4) -20.00 <fL / f<-1.61···(4) f: focal length of the imaging lens optical system fL: focal length of the final lens

[0058] Equation (4) is an equation for appropriately defining the ratio between the focal length of the optical system of the imaging lens and the focal length of the final lens. Satisfying equation (4) is preferable from the viewpoint of shortening the total optical length, since the final lens has negative refractive power and the optical system has a positive-negative telephoto configuration.

[0059] From the viewpoint of shortening the total optical length, fL / f is preferably -15.00 or more, more preferably -12.50 or more, and even more preferably -8.00 or more. Also, from the viewpoint of shortening the focal length of the optical system of the imaging lens, maintaining a wide angle, and improving and maintaining the resolution performance, fL / f is preferably -1.80 or less, and more preferably -2.20 or less.

[0060] 1-2-5.Formula (5) 0.0 <Dp / f<1.3···(5) Dp: Total thickness of plastic lenses on the object side from the aperture f: focal length of the imaging lens optical system

[0061] Formula (5) is a formula for appropriately defining the ratio between the total thickness of the resin lens on the object side of the aperture and the focal length of the optical system of the imaging lens. Satisfying formula (5) is preferable from the viewpoint of suppressing a decrease in transmittance due to yellowing of the resin, since the total thickness of the resin can be made thinner.

[0062] From the viewpoint of realizing the desired optical characteristics by the resin lens, Dp / f is preferably 0.2 or more, more preferably 0.4 or more, and even more preferably 0.6 or more. Also, from the viewpoint of suppressing the decrease in transmittance due to yellowing of the resin lens, Dp / f is preferably 1.2 or less, more preferably 1.0 or less, and even more preferably 0.85 or less.

[0063] 1-2-6.Formula (6) 0.00 <Dp2 / f<1.00···(6) Dp2: the sum of the center thicknesses of the resin lenses on the object side of the aperture stop, other than the resin lenses having negative refractive power included in the resin lens set f: focal length of the imaging lens optical system

[0064] Formula (6) is a formula for appropriately defining the ratio between the sum of the center thicknesses of the resin lenses on the object side of the aperture, other than the resin lens having negative refractive power included in the resin lens set described above, and the focal length of the optical system of the imaging lens. It is preferable to satisfy formula (6) from the viewpoint of suppressing a decrease in transmittance due to yellowing of the resin lens.

[0065] Of a pair of adjacent resin lenses in a resin lens set, the resin lens with smaller dispersion tends to yellow more easily than the other resin lens. From the viewpoint of realizing the desired optical characteristics with the resin lens, Dp2 / f is preferably 0.31 or more, and more preferably 0.40 or more. Also, from the viewpoint of suppressing the decrease in transmittance due to yellowing of the resin lens, Dp2 / f is preferably 0.80 or less, and more preferably 0.60 or less.

[0066] 1-2-7.Formula (7) 1.1 <ImgH / f<2.5···(7) ImgH: Maximum image height f: focal length of the imaging lens optical system

[0067] Equation (7) is an equation for appropriately defining the ratio between the maximum image height and the focal length of the optical system of the imaging lens. Satisfying equation (7) is preferable from the viewpoint of achieving both an appropriate range of distortion and a wide angle, and realizing high resolution.

[0068] From the viewpoint of achieving small distortion and a wide angle by shortening the focal length of the optical system of the imaging lens, ImgH / f is preferably 1.25 or more, and more preferably 1.5 or more. Also, from the viewpoint of achieving high resolution by increasing the distortion and widening the angle, ImgH / f is preferably 2.3 or less, more preferably 2.1 or less, and even more preferably 1.98 or less.

[0069] 1-2-8.Formula (8) -9.0 <f1 / f<-2.5···(8) f: focal length of the imaging lens optical system f1: focal length of the first lens

[0070] Equation (8) is an equation for appropriately defining the ratio between the focal length of the optical system of the imaging lens and the focal length of the first lens. Satisfying equation (8) is preferable from the viewpoint of achieving both an appropriate range of distortion and a wide angle, and realizing high resolution.

[0071] From the viewpoint of achieving small distortion and a wide angle by shortening the focal length of the optical system of the imaging lens, f1 / f is preferably -8.5 or more, more preferably -8.0 or more, and even more preferably -7.0 or more. Also, from the viewpoint of achieving high resolution by increasing the distortion and widening the angle, f1 / f is preferably -3.0 or less, more preferably -3.4 or less, and even more preferably -3.7 or less.

[0072] 1-2-9.Formula (9) 4.0 <TL / f<9.0···(9) TL: Total length of the imaging lens optical system f: focal length of the imaging lens optical system

[0073] Equation (9) is an equation for appropriately defining the ratio between the total length of the optical system of the imaging lens and the focal length of the optical system of the imaging lens. The total length of the optical system of the imaging lens refers to the distance from the object-side lens surface of the lens closest to the object on the optical axis of the optical system of the imaging lens to the image plane. Satisfying equation (9) is preferable from the viewpoint of achieving both an appropriate range of distortion and a wide angle, and realizing high resolution.

[0074] From the viewpoints of small distortion, wide-angle, and shortening the total optical length, TL / f is preferably 5.5 or more, more preferably 5.7 or more, and even more preferably 6.2 or more. Also, from the viewpoint of wide-angle by increasing distortion, TL / f is preferably 7.8 or less, more preferably 7.2 or less, and even more preferably 6.9 or less.

[0075] 1-2-10.Formula (10) -1.7<Σ(fn / VLn)<-0.3 (10) fn: focal length of any lens having negative refractive power among the lenses constituting the imaging lens VLn: Abbe number of any lens having negative refractive power among the lenses constituting the imaging lens

[0076] Formula (10) is a formula for appropriately defining the sum of the ratios of the focal length to the Abbe number for each lens having negative refractive power among the lenses constituting the imaging lens. Here, the nth lens refers to the nth lens from the object side. It is preferable to satisfy formula (10) from the viewpoint of appropriately correcting chromatic aberration.

[0077] From the viewpoint of appropriately correcting chromatic aberration, Σ(fn / VLn) is preferably -1.5 or more, more preferably -1.4 or more, and even more preferably -1.3 or more. Also, from the viewpoint of balancing chromatic aberration and Petzval sum, Σ(fn / VLn) is preferably -0.4 or less, more preferably -0.55 or less, and even more preferably -0.65 or less.

[0078] 1-2-11.Formula (11) 1.40<(RL1+RL2) / (RL1-RL2)<2.65...(11) RL1: Paraxial radius of curvature of the object side surface of the first lens RL2: Paraxial radius of curvature of the image surface side of the first lens

[0079] Formula (11) is a formula for appropriately defining the shaping factor of the first lens. Satisfying formula (11) is preferable from the standpoints of realizing a wider angle and higher resolution while reducing the amount of distortion generated in the first lens.

[0080] From the viewpoint of increasing the distortion and widening the angle, (RL1+RL2) / (RL1-RL2) is preferably 1.55 or more, more preferably 1.70 or more, and even more preferably 1.80 or more. Also, from the viewpoint of increasing the angle while keeping the distortion small, (RL1+RL2) / (RL1-RL2) is preferably 2.45 or less, more preferably 2.35 or less, and even more preferably 2.00 or less.

[0081] 1-2-12.Formula (12) 50 <V1<85···(12) V1: Abbe number of the first lens at the d-line

[0082] Expression (12) is an expression for appropriately defining the Abbe number of the first lens. Satisfying expression (12) is preferable from the viewpoint of achieving both a wider angle of the imaging lens and a reduced lateral chromatic aberration.

[0083] From the viewpoint of reducing lateral chromatic aberration, V1 is preferably equal to or greater than 56, more preferably equal to or greater than 58, and even more preferably equal to or greater than 60. Furthermore, from the viewpoint of achieving a wider angle of the imaging lens, V1 is preferably equal to or less than 80, more preferably equal to or less than 78, and even more preferably equal to or less than 72.

[0084] 1-2-13.Formula (13) 18 <V3<28···(13) V3: Abbe number of the third lens at the d-line

[0085] Expression (13) is an expression for appropriately defining the Abbe number of the third lens. Satisfying expression (13) is preferable from the viewpoint of achieving both correction of coma aberration and reduction of chromatic aberration.

[0086] From the viewpoint of reducing chromatic aberration, V3 is preferably equal to or greater than 20, more preferably equal to or greater than 22, and more preferably equal to or greater than 24. Furthermore, from the viewpoint of achieving coma aberration correction, V3 is preferably equal to or less than 27, more preferably equal to or less than 26, and even more preferably equal to or less than 25.5.

[0087] 1-2-14.Formula (14) 1.48 <N1<1.75···(14) N1: Refractive index of the first lens at the d line

[0088] Expression (14) is an expression for appropriately defining the refractive index of the first lens. Satisfying expression (14) is preferable from the viewpoint of achieving both a wider angle and a reduced lateral chromatic aberration.

[0089] From the viewpoint of realizing a wide angle, N1 is preferably 1.49 or more, more preferably 1.50 or more, and even more preferably 1.52 or more. Also, from the viewpoint of reducing lateral chromatic aberration, N1 is preferably 1.72 or less, more preferably 1.69 or less, and even more preferably 1.60 or less.

[0090] 1-2-15.Formula (15) 0.69 <DL / TL<0.93···(15) DL: Total thickness of the optical system of the imaging lens TL: Total length of the imaging lens optical system

[0091] Equation (15) is an equation for properly defining the ratio between the total thickness of the optical system of the imaging lens and the total length of the optical system of the imaging lens. The total thickness of the optical system of the imaging lens represents the distance from the object side surface of the first lens to the image side surface of the final lens. Satisfying equation (15) is preferable from the viewpoint of simultaneously shortening the total length of the optical system of the imaging lens and properly correcting distortion.

[0092] From the viewpoint of appropriately correcting distortion caused by arranging the final lens having a negative refractive power close to the image plane, DL / TL is preferably 0.72 or more, more preferably 0.73 or more, and even more preferably 0.75 or more. Also, from the viewpoint of shortening the total optical length by shortening the back focus, DL / TL is preferably 0.91 or less, more preferably 0.88 or less, and even more preferably 0.85 or less.

[0093] 1-2-16.Formula (16) 0.01 <DpL / f<0.33···(16) DpL: The distance on the optical axis between the lens that is located closest to the image plane among the lenses with positive refractive power (also called "positive lenses") included in the imaging lens and the lens that is located on the object side of the lens f: focal length of the imaging lens optical system

[0094] Formula (16) is a formula for properly defining the ratio of the distance on the optical axis between the positive lens closest to the image plane and the lens adjacent to it closest to the object, relative to the focal length of the optical system of the imaging lens. Satisfying formula (16) is preferable from the viewpoint of both shortening the overall length of the optical system of the imaging lens and correcting coma aberration.

[0095] From the viewpoint of appropriately correcting coma aberration occurring on the object side of the positive lens, DpL / f is preferably 0.02 or more, more preferably 0.035 or more, and even more preferably 0.04 or more. Also, from the viewpoint of shortening the overall length of the optical system of the imaging lens, DpL / f is preferably 0.28 or less, more preferably 0.25 or less, and even more preferably 0.23 or less.

[0096] 1-2-17.Formula (17) 0.4 <Bf / f<1.7···(17) Bf: Back focus of the optical system of the imaging lens f: focal length of the imaging lens optical system

[0097] Equation (17) is an equation for appropriately defining the ratio of the back focus to the focal length of the optical system of the imaging lens. Satisfying equation (17) is preferable from the viewpoint of both shortening the overall length of the optical system of the imaging lens and correcting distortion aberration.

[0098] From the viewpoint of appropriately correcting distortion caused by arranging the final lens near the image plane, Bf / f is preferably 0.5 or more, more preferably 0.55 or more, and even more preferably 0.65 or more. Also, from the viewpoint of shortening the overall length of the optical system by reducing the back focus of the imaging lens, Bf / f is preferably 1.55 or less, more preferably 1.4 or less, and even more preferably 1.1 or less.

[0099] 2. Imaging device Next, an imaging device according to an embodiment of the present invention will be described. The imaging device is characterized by including the imaging lens according to the embodiment described above and an imaging element provided on the image plane side of the imaging lens for converting an optical image formed by the imaging lens into an electrical signal.

[0100] Here, the imaging element is not particularly limited, and a solid-state imaging element such as a CCD (Charge Coupled Device) sensor and a CMOS (Complementary Metal Oxide Semiconductor) sensor can be used. The imaging device may further include optical elements other than a lens, such as a silver halide film, an infrared cut filter (IRCF), and a plane-parallel plate. The imaging device according to the present embodiment is suitable for an imaging device using a solid-state imaging element. The imaging device may be a fixed-lens imaging device in which a lens is fixed to a housing, or may be an interchangeable-lens imaging device such as a single-lens reflex camera or a mirrorless single-lens camera.

[0101] Fig. 13 is a diagram showing a schematic example of the configuration of an imaging device according to this embodiment. As shown in Fig. 13, a mirrorless single-lens camera 1 has a body 2 and a lens barrel 3 that is detachable from the body 2. The mirrorless single-lens camera 1 is one form of an imaging device.

[0102] The lens barrel 3 has an imaging lens. The imaging lens includes a first lens L1, a second lens L2, a third lens L3, an aperture, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7. The imaging lens is configured to satisfy, for example, the above-mentioned formulas (1) and (2). The imaging lens is also configured to satisfy, for example, the above-mentioned formulas (3) and (4).

[0103] The first lens L1 has negative refractive power. The second lens L2 has negative refractive power. The third lens L3 has positive refractive power. The fourth lens L4 has positive refractive power. The fifth lens L5 has negative refractive power. The sixth lens L6 has positive refractive power. The seventh lens L7 has negative refractive power.

[0104] The main body 2 has a CCD sensor and an infrared cut filter IRCF as an imaging element. The CCD sensor is disposed in the main body 2 at a position where the optical axis OA of the imaging lens in the lens barrel 3 attached to the main body 2 is the central axis. The main body 2 may have a parallel plane plate having no substantial refractive power, such as a cover glass, instead of the infrared cut filter IRCF22, and even in this case, there is no problem in terms of resolution performance.

[0105] In addition to the above-mentioned configuration, the imaging device of this embodiment preferably has an image processing unit, an image correction data storage unit, and the like. The image processing unit electrically processes the captured image data acquired by the imaging element to change the shape of the captured image. The image correction data storage unit stores image correction data and an image correction program used to process the captured image data in the image processing unit. In general, when a lens is made small, distortion (curvature) of the captured image shape formed on the imaging surface is likely to occur. The above-mentioned configuration further including the image processing unit and the like makes it possible to appropriately correct the shape and distortion of the captured image using, for example, the distortion correction data stored in the image correction data storage unit. For this reason, the above-mentioned configuration is preferable from the viewpoint of obtaining a beautiful captured image and miniaturizing the entire imaging device.

[0106] Furthermore, it is preferable that the image correction data storage unit has magnification chromatic aberration correction data for correcting the magnification chromatic aberration, and the image processing unit corrects the magnification chromatic aberration in the captured image using the magnification chromatic aberration correction data. Such a configuration capable of correcting the magnification chromatic aberration is also preferable from the viewpoint of obtaining a beautiful captured image and miniaturizing the entire imaging device.

[0107] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the different embodiments are also included in the technical scope of the present invention.

[0108] (summary) An imaging lens according to a first aspect of the present invention has seven to nine lenses including, in order from the object side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, and a final lens arranged closest to the image side and having negative refractive power, and an aperture, wherein the imaging lens has independent resin lens sets on each of the object side and the image side of the aperture, and the resin lens set consists of a resin lens having positive refractive power and a resin lens having negative refractive power that are adjacent to each other, and one of the resin lenses included in the resin lens set has a refractive index at the d-line that is smaller than 1.68, has an Abbe number greater than 20 and less than 30, and satisfies the following formula: -0.50 <f×Φ2pf<0.42···(1) 0.0 <f×Φ2pb<0.7···(2) however, f: focal length of the imaging lens optical system Φ2pf: The reciprocal of the composite focal length of the two plastic lenses that make up the plastic lens set on the object side of the aperture Φ2pb: The reciprocal of the composite focal length of the two plastic lenses that make up the plastic lens set on the image side of the aperture

[0109] The imaging lens according to Aspect 2 of the present invention is the same as Aspect 1, in that the third lens has a convex surface on the image plane side and satisfies the following formula: -2.3 <f2 / f<0.0···(3) however, f2: focal length of second lens f: focal length of the imaging lens optical system

[0110] The imaging lens according to Aspect 3 of the present invention, in Aspect 1 or 2, satisfies the following formula: -20.00 <fL / f<-1.61···(4) however, fL: focal length of the final lens f: focal length of the imaging lens optical system

[0111] The imaging lens according to Aspect 4 of the present invention is any one of Aspects 1 to 3, in which the number of lenses is eight or less.

[0112] The imaging lens according to Aspect 5 of the present invention is the same as any one of Aspects 1 to 4, in which the final lens has a convex surface on the image surface side.

[0113] The imaging lens according to aspect 6 of the present invention is any one of aspects 1 to 5, in which the first lens has a concave surface on the image surface side.

[0114] The imaging lens according to Aspect 7 of the present invention is any one of Aspects 1 to 6, in which the second lens has a meniscus shape and has a concave surface on the image surface side.

[0115] The imaging lens according to aspect 8 of the present invention, in any one of aspects 1 to 7, satisfies the following formula: 0.0 <Dp / f<1.3···(5) however, Dp: Total thickness of plastic lenses on the object side from the aperture f: focal length of the imaging lens optical system

[0116] The imaging lens according to Aspect 9 of the present invention, in any one of Aspects 1 to 8, satisfies the following formula: 0.00 <Dp2 / f<1.00···(6) however, Dp2: the sum of the center thicknesses of the resin lenses on the object side of the aperture stop, other than the resin lenses having negative refractive power included in the resin lens set f: focal length of the imaging lens optical system

[0117] The imaging lens according to Aspect 10 of the present invention, in any one of Aspects 1 to 9, satisfies the following formula: 1.1 <ImgH / f<2.5···(7) however, ImgH: Maximum image height f: focal length of the imaging lens optical system

[0118] An imaging lens according to an eleventh aspect of the present invention is configured in such a manner that, in any one of the first to tenth aspects, the two resin lenses constituting the resin lens set are not cemented together.

[0119] The imaging lens according to Aspect 12 of the present invention, in any one of Aspects 1 to 11, satisfies the following formula: -9.0 <f1 / f<-2.5···(8) however, f1: focal length of the first lens f: focal length of the imaging lens optical system

[0120] An imaging device according to a thirteenth aspect of the present invention includes the imaging lens according to any one of aspects 1 to 12, and an imaging element on the image plane side of the imaging lens that converts an optical image formed by the imaging lens into an electrical signal. EXAMPLES

[0121] An embodiment of the present invention will be described below. In the following tables, unless otherwise specified, all units of length are "mm", all units of angle of view are "°", and "E+a" is "×10 a ".

[0122] [Example 1] 1 is a diagram showing a schematic optical configuration of the imaging lens of Example 1 when focused at 700 mm. The imaging lens of Example 1 is composed of, in order from the object side, a first lens L1 having negative refractive power, a second lens L2 having negative refractive power, a third lens L3 having positive refractive power, an aperture stop S, a fourth lens L4 having positive refractive power, a fifth lens L5 having negative refractive power, a sixth lens L6 having positive refractive power, and a seventh lens L7 having negative refractive power.

[0123] The first lens L1 has a negative meniscus shape and has a convex surface on the object side. The second lens L2 has a negative meniscus shape and has a convex surface on the object side. The third lens L3 has a biconvex shape. The fourth lens L4 has a biconvex shape. The fifth lens L5 has a biconcave shape. The sixth lens L6 has a biconvex shape. The seventh lens L7 has a negative meniscus shape and has a convex surface on the image side.

[0124] The aperture diaphragm S is disposed on the image side of the third lens L3. The first lens L1, the second lens L2, and the third lens L3, which are disposed on the object side of the aperture diaphragm S, constitute the first lens group described above. The fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7, which are disposed on the image side of the aperture diaphragm S, constitute the second lens group described above. The second lens L2 and the third lens L3 are plastic lenses, and the set of these two lenses corresponds to the plastic lens set on the object side of the diaphragm described above. The fifth lens L5 and the sixth lens L6 are plastic lenses, and the set of these two lenses corresponds to the plastic lens set on the image side of the diaphragm described above. The seventh lens L7 corresponds to the final lens described above.

[0125] "IRCF" is a cover glass with an infrared cut filter function. These points are the same as those in the drawings that show the optical configurations of other examples, so the explanation will be omitted below.

[0126] Next, a numerical example will be described in which specific numerical values ​​of the imaging lens are applied. Table 1 shows surface data of the imaging lens.

[0127] In the surface data table for the embodiment of the present invention, "No." indicates the order of the lens surface counted from the object side, "r" indicates the radius of curvature of the lens surface, "d" indicates the distance between the lens surfaces on the optical axis, "Nd" indicates the refractive index for the d-line (wavelength λ=587.6 nm), "vd" indicates the Abbe number for the d-line, and an "*" in the "ASP" column next to the surface number indicates that the lens surface is aspheric. "S" in the "No." column indicates the aperture stop. The first surface number in the table, "-", indicates the object surface. Also, when the radius of curvature r is "0", this means that the surface is flat.

[0128] In Table 1, No. 1 and 2 are surface numbers of the first lens L1. No. 3 and 4 are surface numbers of the second lens L2. No. 5 and 6 are surface numbers of the third lens L3. No. 7 is the surface number of the aperture stop. No. 8 and 9 are surface numbers of the fourth lens L4. No. 10 and 11 are surface numbers of the fifth lens L5. No. 12 and 13 are surface numbers of the sixth lens L6. No. 14 and 15 are surface numbers of the seventh lens L7. No. 16 and No. 17 are surface numbers of the cover glass.

[0129] [Table 1] No. ASP rd Nd vd - 700 700 1 11.870 0.600 1.6200 63.88 2 3.326 1.577 3 * 21.184 0.400 1.5447 55.86 4 * 1.614 1.338 5 * 15.260 0.788 1.6393 23.35 6 * -6.447 0.758 7S 0.000 0.325 8 3.230 1.782 1.5503 75.50 9 -3.230 0.100 10 * -10.765 0.406 1.6393 23.35 11 * 2.409 0.154 12 * 2.720 2.376 1.5447 55.86 13 * -2.442 0.280 14 -3.224 0.400 1.7552 27.53 15 -6.911 1.111 16 0.000 0.200 1.51680 64.20 17 1.605

[0130] Table 2 shows the specifications of the imaging lens of Example 1. In this specification table, "f" represents the focal length of the imaging lens, "Fno" represents the F-number, and "Cra" represents the chief ray axis angle. Here, the chief ray axis angle is the angle of the chief ray entering the image plane.

[0131] [Table 2] Number of lenses: 7 f 2.183 Fno 2.200 Cra 20.0

[0132] Table 3 shows the aspheric coefficients of the aspheric surfaces in the imaging lens of Example 1. The aspheric coefficients in this table are values ​​when each aspheric shape is defined by the following formula (I).

[0133]

number

[0134] In the above formula, "X(Y)" is a function indicating the amount of displacement of the aspheric surface in the optical axis direction from a reference surface perpendicular to the optical axis, "C" is the curvature at the surface vertex, "Y" is the height (distance) from the optical axis to the aspheric surface in the direction perpendicular to the optical axis, "k" is the conic constant (conic coefficient), and "An" (n is an integer) is the n-th order aspheric coefficient.

[0135] [Table 3] No. k A4 A6 4 1.00 2.50647E-02 -8.83695E-03 5 1.00 4.43666E-02 -2.20647E-02 6 1.00 -1.67150E-02 -4.45453E-03 7 1.00 -2.67290E-02 -2.25147E-04 11 1.00 -6.35990E-02 1.13840E-02 12 1.00 -8.03413E-02 2.20859E-02 13 1.00 -4.27954E-02 3.38596E-03 14 1.00 2.11046E-03 0.00000E+00 No. A8 A10 A12 4 1.12430E-03 -5.55502E-05 0.00000E+00 5 1.82887E-02 -1.04883E-02 0.00000E+00 6 -3.47274E-04 -6.66489E-03 0.00000E+00 7 -9.65275E-03 2.30391E-03 0.00000E+00 11 3.34208E-04 -1.93636E-03 0.00000E+00 12 -3.64459E-03 8.06253E-05 0.00000E+00 13 1.17047E-04 -1.34058E-04 0.00000E+00 14 0.00000E+00 0.00000E+00 0.00000E+00

[0136] Table 4 shows the focal length of each lens constituting the imaging lens of the first embodiment.

[0137] [Table 4] Lens No. Focal length 1 -7.659 2 -3.231 3 7.192 4 3.253 5 -3.043 6 2.820 7 -8.394

[0138] 2 is a diagram showing longitudinal aberration diagrams of the imaging lens of Example 1 when focused at 700 mm. The longitudinal aberration diagrams shown in each diagram are, from the left as you face the drawing, spherical aberration (mm), astigmatism (mm), and distortion aberration (%), respectively. The same applies to the other examples.

[0139] In the diagram showing spherical aberration, the vertical axis represents the ratio to the maximum open F-number, and the horizontal axis represents defocus. In the diagram showing spherical aberration, the chain line represents spherical aberration at the d-line (wavelength λ=587.5618 nm), the dotted line represents spherical aberration at a wavelength λ=940.0000 nm, the solid line represents spherical aberration at the C-line (wavelength λ=656.2725 nm), and the chain line represents spherical aberration at the F-line (wavelength λ=486.1327 nm). At the 100% position of the pupil in the diagram showing spherical aberration, the chain line representing the F-line, the chain line representing the d-line, the solid line representing the C-line, and the dotted line representing the wavelength λ=940.0000 nm are lined up from the left side of the drawing.

[0140] In the diagram showing astigmatism, the vertical axis represents the angle of view and the horizontal axis represents the defocus. In the diagram showing astigmatism, the dashed line represents the sagittal image plane (S) for the d-line, and the four-dot chain line represents the meridional image plane (T) for the d-line.

[0141] In the diagram showing distortion, the vertical axis represents the angle of view, and the horizontal axis represents %, and the dashed line represents distortion at the d-line.

[0142] The above-mentioned explanation regarding the table and the matters regarding the longitudinal aberration diagram are the same in the other embodiments, and therefore the explanation will be omitted below.

[0143] [Example 2] 3 is a diagram showing a schematic optical configuration of the imaging lens of Example 2 at a focus distance of 700 mm. The imaging lens of Example 2 is composed of, in order from the object side, a first lens L1 having negative refractive power, a second lens L2 having negative refractive power, a third lens L3 having positive refractive power, a fourth lens L4 having positive refractive power, an aperture stop S, a fifth lens L5 having positive refractive power, a sixth lens L6 having negative refractive power, a seventh lens L7 having positive refractive power, and an eighth lens L8 having negative refractive power.

[0144] The first lens L1 has a negative meniscus shape and has a convex surface on the object side. The second lens L2 has a negative meniscus shape and has a convex surface on the object side. The third lens L3 has a convex surface on the image side. The fourth lens L4 has a concave surface on the object side and a convex surface on the image side. The fifth lens L5 has a biconvex shape. The sixth lens L6 has a biconcave shape. The seventh lens L7 has a biconvex shape. The eighth lens L8 has a negative meniscus shape and has a convex surface on the image side.

[0145] The aperture diaphragm S is disposed on the image side of the fourth lens L4. The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4, which are disposed on the object side of the aperture diaphragm S, constitute the first lens group described above. The fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8, which are disposed on the image side of the aperture diaphragm S, constitute the second lens group described above. The second lens L2 and the third lens L3 are plastic lenses, and the set of these two lenses corresponds to the plastic lens set on the object side of the diaphragm described above. The sixth lens L6 and the seventh lens L7 are plastic lenses, and the set of these two lenses corresponds to the plastic lens set on the image side of the diaphragm described above. The eighth lens L8 corresponds to the final lens described above.

[0146] Table 5 shows the surface data of the imaging lens.

[0147] [Table 5] No. ASP rd Nd vd - 700 700 1 12.909 0.600 1.5935 67.00 2 3.571 1.324 3 * 9.143 0.403 1.5447 55.86 4 * 1.623 1.504 5 * 4157.556 0.896 1.6393 23.35 6 * -3.355 0.100 7 -2.152 0.710 1.8042 46.50 8 -3.016 0.100 9S 0.000 0.101 10 3.594 1.947 1.4970 81.61 11 -2.099 0.100 12 * -3.331 0.400 1.6393 23.35 13 * 4.473 0.169 14 * 4.164 2.202 1.5447 55.86 15 * -2.367 0.680 16 -3.345 0.400 1.86970 20.02 17 -5.477 0.760 18 0.000 0.200 1.5168 64.1983 19 0.000 1.605

[0148] Table 6 shows the specifications of the imaging lens of the second embodiment.

[0149] [Table 6] Number of lenses: 8 f 2.008 Fno 2.200 Cra 24.6

[0150] Table 7 shows the aspheric coefficients of the aspheric surface in the imaging lens of Example 2.

[0151] [Table 7] No. k A4 A6 3 0.00 4.34329E-02 -1.09093E-02 4 0.00 5.78845E-02 -9.81146E-03 5 0.00 -2.13395E-02 1.61479E-02 6 0.00 -2.55478E-02 3.07277E-03 12 0.00 -4.93431E-02 9.95146E-03 13 0.00 -4.72026E-02 2.24194E-02 14 0.00 -3.81349E-02 7.25573E-03 15 0.00 1.13085E-03 0.00000E+00 No. A8 A10 A12 3 1.02587E-03 -3.63210E-05 0.00000E+00 4 1.04755E-02 -8.19866E-03 0.00000E+00 5 -2.36362E-02 6.46186E-03 0.00000E+00 6 -8.59780E-03 5.25169E-03 0.00000E+00 12 -3.50929E-03 -2.65482E-03 0.00000E+00 13 -5.89121E-03 5.00640E-04 0.00000E+00 14 -1.04660E-03 -2.66265E-05 0.00000E+00 15 0.00000E+00 0.00000E+00 0.00000E+00

[0152] Table 8 shows the focal length of each lens constituting the imaging lens of Example 2.

[0153] [Table 8] Lens No. Focal length 1 -8.520 2 -3.692 3 5.244 4 -14.740 5 3.008 6 -2.928 7 3.144 8 -10.825

[0154] FIG. 4 is a diagram showing longitudinal aberration of the imaging lens of Example 2 when focused at 700 mm.

[0155] [Example 3] 5 is a diagram showing a schematic optical configuration of the imaging lens of Example 3 at a focus distance of 700 mm. The imaging lens of Example 3 is composed of, in order from the object side, a first lens L1 having negative refractive power, a second lens L2 having negative refractive power, a third lens L3 having positive refractive power, an aperture stop S, a fourth lens L4 having positive refractive power, a fifth lens L5 having negative refractive power, a sixth lens L6 having positive refractive power, and a seventh lens L7 having negative refractive power.

[0156] The first lens L1 has a negative meniscus shape and has a convex surface on the object side. The second lens L2 has a negative meniscus shape and has a convex surface on the object side. The third lens L3 has a biconvex shape. The fourth lens L4 has a biconvex shape. The fifth lens L5 has a biconcave shape. The sixth lens L6 has a biconvex shape. The seventh lens L7 has a negative meniscus shape and has a convex surface on the image side.

[0157] The aperture diaphragm S is disposed on the image side of the third lens L3. The first lens L1, the second lens L2, and the third lens L3, which are disposed on the object side of the aperture diaphragm S, constitute the first lens group described above. The fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7, which are disposed on the image side of the aperture diaphragm S, constitute the second lens group described above. The second lens L2 and the third lens L3 are plastic lenses, and the set of these two lenses corresponds to the plastic lens set on the object side of the diaphragm described above. The fifth lens L5 and the sixth lens L6 are plastic lenses, and the set of these two lenses corresponds to the plastic lens set on the image side of the diaphragm described above. The seventh lens L7 corresponds to the final lens described above.

[0158] Table 9 shows the surface data of the imaging lens.

[0159] [Table 9] No. ASP rd Nd vd - 700 700 1 11.839 0.600 1.6200 63.88 2 3.588 1.324 3 * 11.437 0.403 1.5447 55.86 4 * 1.613 1.504 5 * -10.539 0.896 1.6393 23.35 6 * -3.239 0.100 7S 0.000 0.710 8 9.000 0.100 1.5503 75.50 9 -2.078 0.101 10 * -3.060 1.947 1.6393 23.35 11 * 11.133 0.100 12 * 2.915 0.400 1.5447 55.86 13 * -2.741 0.169 14 -3.357 2.202 1.9229 20.88 15 -9.623 0.680 16 0.000 0.400 1.51680 64.20 17 0.000 0.760

[0160] Table 10 shows the specifications of the imaging lens of the third embodiment.

[0161] [Table 10] Number of lenses: 7 f 2.075 Fno 2.200 Cra 24.6

[0162] Table 11 shows the aspheric coefficients of the aspheric surface in the imaging lens of the third embodiment.

[0163] [Table 11] No. k A4 A6 3 1.00 3.88181E-02 -1.01334E-02 4 1.00 5.72648E-02 -1.57647E-02 5 1.00 -2.90574E-02 9.23880E-03 6 1.00 -1.60128E-02 -9.81503E-04 12 1.00 -4.74609E-02 9.55501E-03 13 1.00 -5.80763E-02 2.23862E-02 14 1.00 -2.99392E-02 3.60730E-03 15 1.00 4.24887E-03 0.00000E+00 No. A8 A10 A12 3 9.94153E-04 -3.99216E-05 0.00000E+00 4 1.83197E-02 -1.10399E-02 0.00000E+00 5 -2.08015E-02 4.72637E-03 0.00000E+00 6 -5.17960E-03 3.16928E-03 0.00000E+00 12 2.26591E-03 -3.31927E-03 0.00000E+00 13 -5.37105E-03 4.13436E-04 0.00000E+00 14 -5.16583E-04 -3.50694E-06 0.00000E+00 15 0.00000E+00 0.00000E+00 0.00000E+00

[0164] Table 12 shows the focal length of each lens constituting the imaging lens of Example 3.

[0165] [Table 12] Lens No. Focal length 1 -8.541 2 -3.499 3 6.932 4 3.235 5 -3.714 6 3.046 7 -5.762

[0166] FIG. 6 is a diagram showing longitudinal aberration of the imaging lens of Example 3 when focused at 700 mm.

[0167] [Example 4] 7 is a diagram showing a schematic optical configuration of the imaging lens of Example 4 when focused at 700 mm. The imaging lens of Example 4 is composed of, in order from the object side, a first lens L1 having negative refractive power, a second lens L2 having negative refractive power, a third lens L3 having positive refractive power, a fourth lens L4 having positive refractive power, an aperture stop S, a fifth lens L5 having positive refractive power, a sixth lens L6 having negative refractive power, a seventh lens L7 having positive refractive power, and an eighth lens L8 having negative refractive power.

[0168] The first lens L1 has a negative meniscus shape and has a convex surface on the object side. The second lens L2 has a negative meniscus shape and has a convex surface on the object side. The third lens L3 has a convex surface on the image side. The fourth lens L4 has a concave surface on the object side and a convex surface on the image side. The fifth lens L5 has a biconvex shape. The sixth lens L6 has a biconcave shape. The seventh lens L7 has a biconvex shape. The eighth lens L8 has a negative meniscus shape and has a convex surface on the image side.

[0169] The aperture diaphragm S is disposed on the image side of the fourth lens L4. The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4, which are disposed on the object side of the aperture diaphragm S, constitute the first lens group described above. The fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8, which are disposed on the image side of the aperture diaphragm S, constitute the second lens group described above. The second lens L2 and the third lens L3 are plastic lenses, and the set of these two lenses corresponds to the plastic lens set on the object side of the diaphragm described above. The sixth lens L6 and the seventh lens L7 are plastic lenses, and the set of these two lenses corresponds to the plastic lens set on the image side of the diaphragm described above. The eighth lens L8 corresponds to the final lens described above.

[0170] Table 13 shows the surface data of the imaging lens.

[0171] [Table 13] No. ASP rd Nd vd - 700 700 1 13.723 0.600 1.6658 58.61 2 3.723 0.943 3 * 10.464 0.400 1.5447 55.86 4 * 1.746 1.342 5 * 22.362 1.501 1.6150 25.92 6 * -3.641 0.100 7 -2.549 0.892 1.8042 46.50 8 -2.906 0.213 9S 0.000 0.167 10 4.988 1.819 1.4970 81.61 11 -2.078 0.100 12 * -3.067 0.400 1.6150 25.92 13 * 2.998 0.150 14 * 3.120 1.994 1.5447 55.86 15 * -3.031 1.112 16 -3.551 0.400 1.86966 20.02 17 -4.649 0.382 18 0.000 0.200 1.5168 64.2 19 0.000 1.485

[0172] Table 14 shows the specifications of the imaging lens of the fourth embodiment.

[0173] [Table 14] Number of lenses: 8 f 2.008 Fno 2.200 Cra 24.2

[0174] Table 15 shows the aspheric coefficients of the aspheric surface in the imaging lens of Example 4.

[0175] [Table 15] No. k A4 A6 3 0.00 5.76974E-02 -1.13293E-02 4 0.00 7.46640E-02 3.61940E-04 5 0.00 -2.25686E-02 1.29945E-02 6 0.00 -1.62728E-02 -1.14381E-03 12 0.00 -4.48688E-02 5.40349E-03 13 0.00 -6.40088E-02 1.90932E-02 14 0.00 -5.46232E-02 1.14626E-02 15 0.00 -7.43967E-03 0.00000E+00 No. A8 A10 A12 3 6.91942E-04 9.03814E-06 0.00000E+00 4 7.98953E-03 -6.47631E-03 0.00000E+00 5 -1.34791E-02 2.93638E-03 0.00000E+00 6 2.85621E-03 3.90043E-04 0.00000E+00 12 -7.14006E-03 1.05274E-03 0.00000E+00 13 -4.07592E-03 2.73659E-04 0.00000E+00 14 -1.43129E-03 -9.34161E-06 0.00000E+00 15 0.00000E+00 0.00000E+00 0.00000E+00

[0176] Table 16 shows the focal length of each lens constituting the imaging lens of Example 4.

[0177] [Table 16] Lens No. Focal length 1 -7.861 2 -3.911 3 5.206 4 225.846 5 3.228 6 -2.405 7 3.187 8 -20.835

[0178] FIG. 8 is a diagram showing longitudinal aberration of the imaging lens of Example 4 when focused at 700 mm.

[0179] [Example 5] 9 is a diagram showing a schematic optical configuration of the imaging lens of Example 5 at a focus distance of 700 mm. The imaging lens of Example 5 is composed of, in order from the object side, a first lens L1 having negative refractive power, a second lens L2 having negative refractive power, a third lens L3 having positive refractive power, a fourth lens L4 having positive refractive power, an aperture stop S, a fifth lens L5 having positive refractive power, a sixth lens L6 having negative refractive power, a seventh lens L7 having positive refractive power, an eighth lens L8 having positive refractive power, and a ninth lens L9 having negative refractive power.

[0180] The first lens L1 has a negative meniscus shape and has a convex surface on the object side. The second lens L2 has a negative meniscus shape and has a convex surface on the object side. The third lens L3 has a biconvex shape. The fourth lens L4 has a concave surface on the object side and a convex surface on the image side. The fifth lens L5 has a biconvex shape. The sixth lens L6 has a biconcave shape. The seventh lens L7 has a biconvex shape. The eighth lens L8 has a negative meniscus shape and has a convex surface on the image side. The ninth lens L9 has a negative meniscus shape and has a convex surface on the image side.

[0181] The aperture diaphragm S is disposed on the image side of the fourth lens L4. The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4, which are disposed on the object side of the aperture diaphragm S, constitute the first lens group described above. The fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, and the ninth lens L9, which are disposed on the image side of the aperture diaphragm S, constitute the second lens group described above. The second lens L2 and the third lens L3 are plastic lenses, and the set of these two lenses corresponds to the plastic lens set on the object side of the diaphragm described above. The sixth lens L6 and the seventh lens L7 are plastic lenses, and the set of these two lenses corresponds to the plastic lens set on the image side of the diaphragm described above. The ninth lens L9 corresponds to the final lens described above.

[0182] Table 17 shows the surface data of the imaging lens.

[0183] [Table 17] No. ASP rd Nd vd - 700 700 1 14.377 0.600 1.5153 77.36 2 5.211 0.855 3 * 21.522 0.400 1.5447 55.86 4 * 1.517 1.517 5 * 15.913 0.707 1.6150 25.92 6 * -6.647 0.110 7 -4.002 1.252 8 -3.679 0.100 1.8042 46.50 9S 0.000 0.125 10 6.302 1.844 1.4970 81.61 11 -2.160 0.100 12 * -3.590 0.400 1.6150 25.92 13 * 2.992 0.150 14 * 2.701 2.364 1.5447 55.86 15 * -2.603 0.150 16 -3.768 0.350 1.54472 55.86 17 -3.768 0.990 18 -3.467 0.400 1.86966 20.02 19 -5.758 0.100 20 0 0.2 1.5168 64.2 21 0 1

[0184] Table 18 shows the specifications of the imaging lens of the fifth embodiment.

[0185] [Table 18] Number of lenses: 9 f 2.114 Fno 2.200 Cra 19.9

[0186] Table 19 shows the aspheric coefficients of the aspheric surface in the imaging lens of the fifth embodiment.

[0187] [Table 19] No. k A4 A6 3 0.00 4.54977E-02 -9.17597E-03 4 0.00 5.20719E-02 1.42040E-02 5 0.00 -3.28118E-02 1.26241E-02 6 0.00 -3.12041E-02 -1.40248E-03 12 0.00 -4.89295E-02 5.79219E-03 13 0.00 -6.67060E-02 1.91310E-02 14 0.00 -5.04112E-02 9.66764E-03 15 0.00 -1.18329E-04 0.000475472 No. A8 A10 A12 3 7.71714E-04 -2.16987E-05 0.00000E+00 4 1.01296E-02 -5.23608E-03 0.00000E+00 5 -1.45381E-02 2.59097E-03 0.00000E+00 6 -1.62432E-03 5.10821E-04 0.00000E+00 12 -3.96578E-03 3.09741E-04 0.00000E+00 13 -4.23502E-03 3.70172E-04 0.00000E+00 14 -1.63149E-03 7.53320E-05 0.00000E+00 15 2.13915E-05 0.00000E+00 0.00000E+00

[0188] Table 20 shows the focal length of each lens constituting the imaging lens of Example 5.

[0189] [Table 20] Lens No. Focal length 1 -16.223 2 -3.018 3 7.716 4 20.777 5 3.489 6 -2.593 7 2.888 8 211.234 9 -10.901

[0190] FIG. 10 is a diagram showing longitudinal aberration of the imaging lens of Example 5 when focused at 700 mm.

[0191] [Example 6] 11 is a diagram showing a schematic optical configuration of the imaging lens of Example 6 at a focus distance of 700 mm. The imaging lens of Example 11 is composed of, in order from the object side, a first lens L1 having negative refractive power, a second lens L2 having negative refractive power, a third lens L3 having positive refractive power, an aperture stop S, a fourth lens L4 having positive refractive power, a fifth lens L5 having negative refractive power, a sixth lens L6 having positive refractive power, and a seventh lens L7 having negative refractive power.

[0192] The first lens L1 has a negative meniscus shape and has a convex surface on the object side. The second lens L2 has a negative meniscus shape and has a convex surface on the object side. The third lens L3 has a biconvex shape. The fourth lens L4 has a biconvex shape. The fifth lens L5 has a negative meniscus shape and has a concave surface on the object side. The sixth lens L6 has a biconvex shape. The seventh lens L7 has a negative meniscus shape and has a convex surface on the image side.

[0193] The aperture diaphragm S is disposed on the image side of the third lens L3. The first lens L1, the second lens L2, and the third lens L3, which are disposed on the object side of the aperture diaphragm S, constitute the first lens group described above. The fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7, which are disposed on the image side of the aperture diaphragm S, constitute the second lens group described above. The second lens L2 and the third lens L3 are plastic lenses, and the set of these two lenses corresponds to the plastic lens set on the object side of the diaphragm described above. The sixth lens L6 and the seventh lens L7 are plastic lenses, and the set of these two lenses corresponds to the plastic lens set on the image side of the diaphragm described above. The seventh lens L7 corresponds to the final lens described above.

[0194] Table 21 shows the surface data of the imaging lens.

[0195] [Table 21] No. ASP rd Nd vd - 700 700 1 11.901 0.509 1.6310 61.56 2 4.717 1.375 3 * 153.743 0.400 1.5447 55.86 4 * 1.613 1.500 5 * -140.886 0.869 1.6393 23.35 6 * -4.939 0.505 7S 0.000 0.101 8 5.958 1.828 1.5334 73.35 9 -2.288 0.100 10 -4.073 0.400 1.6393 23.35 11 7.476 0.532 12 * 2.878 2.484 1.5447 55.86 13 * -2.816 0.154 14 * -3.377 0.553 1.8808 21.64 15 * -10.097 1.079 16 0.000 0.200 1.5168 64.2 17 0.000 1.605

[0196] Table 22 shows the specifications of the imaging lens of the sixth embodiment.

[0197] [Table 22] Number of lenses: 7 f 2.373 Fno 2.200 Cra 18.1

[0198] Table 23 shows the aspheric coefficients of the aspheric surface in the imaging lens of Example 6.

[0199] [Table 23] No. k A4 A6 3 0.00 3.41605E-02 -9.38512E-03 4 0.00 5.42453E-02 -9.82771E-03 5 0.00 -2.81801E-02 8.39836E-04 6 0.00 -2.99399E-02 -4.00991E-03 12 0.00 -6.74428E-02 6.64651E-03 13 0.00 -7.44753E-02 2.30208E-02 14 0.00 -2.64051E-02 2.52014E-03 15 0.00 4.57690E-03 0.00000E+00 No. A8 A10 A12 3 1.06983E-03 -4.46362E-05 1.33143E-10 4 1.97579E-02 -1.20816E-02 0.00000E+00 5 -1.52157E-02 -3.87612E-04 0.00000E+00 6 -8.12563E-03 2.91819E-03 0.00000E+00 12 3.78433E-03 -2.05204E-03 0.00000E+00 13 -4.76512E-03 4.64894E-04 0.00000E+00 14 -2.40136E-04 -2.24746E-05 0.00000E+00 15 0.00000E+00 0.00000E+00 0.00000E+00

[0200] Table 24 shows the focal length of each lens constituting the imaging lens of Example 6.

[0201] [Table 24] Lens No. Focal length 1 -12.732 2 -2.995 3 7.988 4 3.358 5 -4.069 6 3.088 7 -5.992

[0202] FIG. 12 is a diagram showing longitudinal aberration of the imaging lens of Example 6 when focused at 700 mm.

[0203] The values ​​calculated by the above-mentioned formulas in Examples 1 to 6 are shown in Table 25.

[0204] [Table 25] Example 1 Example 2 Example 3 Equation (1) -0.216 0.046 -0.087 Equation (2) 0.353 0.245 0.457 Equation (3) -1.480 -1.838 -1.686 Equation (4) -3.845 -5.391 -2.776 Equation (5) 0.544 0.647 0.691 Equation (6) 0.361 0.446 0.432 Equation (7) 1.747 1.988 1.874 Equation (8) -3.508 -4.243 -4.115 Equation (9) 6.505 7.071 6.842 Equation (10) -0.613 -1.176 -0.631 Equation (11) 1.779 1.765 1.870 Equation (12) 63.880 67.002 63.880 Equation (13) 23.352 23.352 23.352 Equation (14) 1.620 1.594 1.620 Equation (15) 0.795 0.819 0.743 Equation (16) 0.070 0.084 0.048 Equation (17) 1.304 1.243 0.821 Examples 4 to 6 are as follows. Example 4 Example 5 Example 6 Equation (1) 0.080 -0.268 -0.292 Equation (2) 0.059 0.255 0.493 Equation (3) -1.948 -1.427 -1.262 Equation (4) -10.006 -5.172 -2.525 Equation (5) 0.947 0.524 0.535 Equation (6) 0.747 0.334 0.366 Equation (7) 1.975 1.605 1.399 Equation (8) -3.914 -7.673 -5.365 Equation (9) 7.071 6.716 5.981 Equation (10) -1.338 -0.908 -0.712 Equation (11) 1.744 2.137 2.313 Equation (12) 58.610 77.360 61.560 Equation (13) 25.920 25.920 23.350 Equation (14) 1.666 1.515 1.631 Equation (15) 0.854 0.874 0.797 Equation (16) 0.075 0.071 0.224 Equation (17) 0.995 0.583 1.187

[0205] Table 26 shows the values ​​used in the above formulas in Examples 1 to 6.

[0206] [Table 26] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 f 2.183 2.008 2.075 2.008 2.114 2.373 Φ2pf -0.099 0.023 -0.042 0.040 -0.127 -0.123 Φ2pb 0.162 0.122 0.220 0.030 0.120 0.208 f2 -3.231 -3.692 -3.499 -3.911 -3.018 -2.995 fL -8.394 -10.825 -5.762 -20.835 -10.901 -5.992 Dp 1.188 1.300 1.434 1.901 1.107 1.269 Dp2 0.788 0.896 0.896 1.501 0.707 0.869 ImgH 3.814 3.992 3.889 3.967 3.394 3.321 f1 -7.659 -8.520 -8.541 -7.861 -16.223 -12.732 TL 14.200 14.200 14.200 14.200 14.200 14.194 Σfn / VLn -0.613 -1.176 -0.631 -1.338 -0.908 -0.712 RL1 11.870 12.909 11.839 13.723 14.377 11.901 RL2 3.326 3.571 3.588 3.723 5.211 4.717 V1 63.880 67.002 63.880 58.610 77.360 61.560 V3 23.352 23.352 23.352 25.920 25.920 23.350 N1 1.620 1.594 1.620 1.666 1.515 1.631 DL 11.284 11.635 10.555 12.133 12.415 11.310 DpL 0.154 0.169 0.100 0.150 0.150 0.532 Bf 2.847 2.497 1.704 1.999 1.232 2.816 [Explanation of symbols]

[0207] 1. Mirrorless interchangeable-lens camera (imaging device) 2 Main unit 3. Telescope tube L1~L9 1st lens~9th lens OA optical axis S (aperture) aperture IRCF Infrared Cut Filter

Claims

1. An imaging lens having seven to nine lenses including, in order from an object side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, and a final lens which is disposed closest to an image plane and has negative refractive power, and an aperture, a resin lens set is provided on the object side and the image plane side of the aperture, The resin lens set includes a resin lens having a positive refractive power and a resin lens having a negative refractive power, the resin lens set being adjacent to each other, One of the resin lenses included in the resin lens set has a refractive index at d line that is smaller than 1.68 and an Abbe number that is greater than 20 and less than 30; and An imaging lens that satisfies the following formula: −0.50<f×Φ2pf<0.42 … (1) 0.0<f×Φ2pb<0.70 (2) however, f: focal length of the optical system of the imaging lens Φ2pf: the reciprocal of the composite focal length of the two plastic lenses constituting the plastic lens set located closer to the object than the aperture Φ2pb: the reciprocal of the composite focal length of the two plastic lenses constituting the plastic lens set located on the image side of the aperture

2. the third lens has a convex surface on the image side, 2. The imaging lens according to claim 1, which satisfies the following formula: -2.3<f2 / f<0.0...(3) however, f2: focal length of the second lens

3. 2. The imaging lens according to claim 1, which satisfies the following formula: -20.00<fL / f<-1.61...(4) however, fL: focal length of the final lens

4. The imaging lens according to claim 1 , wherein the number of lenses is eight or less.

5. The imaging lens according to claim 1 , wherein the final lens has a convex surface on the image surface side.

6. The imaging lens according to claim 1 , wherein the first lens has a concave surface on the image surface side.

7. The imaging lens according to claim 1 , wherein the second lens has a meniscus shape and has a concave surface on the image surface side.

8. 2. The imaging lens according to claim 1, which satisfies the following formula: 0.0<Dp / f<1.3...(5) however, Dp: the total thickness of the plastic lenses on the object side of the aperture

9. 2. The imaging lens according to claim 1, which satisfies the following formula: 0.00<Dp2 / f<1.00...(6) however, Dp2: the sum of the center thicknesses of the resin lenses on the object side of the aperture stop, other than the resin lens having negative refractive power included in the resin lens set

10. 2. The imaging lens according to claim 1, which satisfies the following formula: 1.1<ImgH / f<2.5...(7) however, ImgH: Maximum image height

11. The imaging lens according to claim 1 , wherein the two resin lenses constituting the resin lens set are not cemented together.

12. 2. The imaging lens according to claim 1, which satisfies the following formula: -9.0<f1 / f<-2.5...(8) however, f1: focal length of the first lens

13. 13. An imaging device comprising: the imaging lens according to claim 1; and an imaging element, provided on an image plane side of the imaging lens, for converting an optical image formed by the imaging lens into an electrical signal.

Images