Fixed-focus optical system and camera device

Abstract

This invention provides a fixed-focus optical system that uniformly corrects chromatic aberration and other aberrations, and an imaging device equipped with the fixed-focus optical system. The fixed-focus optical system comprises a front group, an aperture, and a rear group, arranged sequentially from the object side to the image side. When the refractive index and Abbe number of the lenses included in the fixed-focus optical system are set to Nd and νd, respectively, the fixed-focus optical system includes at least one lens satisfying 2.435 < Nd + 0.01425 × νd < 2.75 and 15 < νd < 39, i.e., a specific lens.

Description

Technical Field

[0001] The present invention relates to a fixed-focus optical system and a camera device. Background Technology

[0002] Previously, as a lens system that can be used in imaging devices such as digital cameras, a fixed-focus lens system as described in Patent Document 1 is known.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-049572

[0004] The requirements for fixed-focus optical systems that demand balanced correction of chromatic aberration and other aberrations are increasing year by year. Summary of the Invention

[0005] The present invention provides a fixed-focus optical system in which chromatic aberration and other aberrations are evenly corrected, and a camera device having the fixed-focus optical system.

[0006] The first aspect of the present invention is a fixed-focus optical system, which consists of a front group, an aperture, and a rear group sequentially from the object side to the image side, wherein...

[0007] The fixed-focus optical system includes at least one specific lens, which is a lens that satisfies the following conditions (1) and (2):

[0008] 2.435<Nd+0.01425×νd<2.75 (1)

[0009] 15<νd<39 (2)。

[0010] Here, the refractive index of the lens included in the fixed-focus optical system relative to the d-line is set as Nd. The Abbe number of the d-line reference of the lens included in the fixed-focus optical system is set as νd.

[0011] The second aspect of the present invention is based on the fixed-focus optical system of the first aspect.

[0012] When the partial dispersion ratio between the g-line and F-line of the lenses included in a fixed-focus optical system is set as θgF,

[0013] A specific lens satisfies the following condition (3):

[0014] 0.65<θgF+0.00316×νd<0.85 (3).

[0015] In the third aspect of the present invention, in the fixed-focus optical system of the first aspect, when the focal length of the front group is set to fF and the focal length of the rear group is set to fR when the object is focused at infinity, the fixed-focus optical system satisfies the following conditional expression (4):

[0016] -5<fR / fF<10 (4)。

[0017] The fourth aspect of the present invention, in the fixed-focus optical system of the first aspect, includes at least one focusing lens group that moves along the optical axis during focusing.

[0018] The fifth aspect of the present invention is based on the fixed-focus optical system of the fourth aspect.

[0019] When the focal length of the focusing lens group with the strongest optical power in the focusing lens group included in the fixed-focus optical system is set to ffocmax, and the focal length of the fixed-focus optical system in the state of focusing on an object at infinity is set to f, the fixed-focus optical system satisfies the following conditional expression (5):

[0020] 0.2<|ffocmax / f|<3.5 (5).

[0021] In the sixth aspect of the present invention, in the fixed-focus optical system of the fourth aspect, the fixed-focus optical system includes two focusing lens groups. When the focal length of the object-side focusing lens group in the two focusing lens groups is set to ff1 and the focal length of the image-side focusing lens group in the two focusing lens groups is set to ff2, the fixed-focus optical system satisfies the following conditional expression (6):

[0022] 0.1<|ff1 / ff2|<10 (6).

[0023] In the fixed-focus optical system of the fourth embodiment of the present invention, the seventh embodiment satisfies the following conditional expression (7) when the combined focal length of all lenses in the fixed-focus optical system that are closer to the object side than the focal lens group in the most object-side focus lens group is set to fcF, and the focal length of the fixed-focus optical system in the state of focusing on an object at infinity is set to f:

[0024] -2<f / ffocF<6 (7)。

[0025] In the fixed-focus optical system of the fourth embodiment of the present invention, the eighth embodiment satisfies the following conditional expression (8) when the combined focal length of all lenses in the fixed-focus optical system that are more image-side than the most image-side focusing lens group is set to ffocR, and the focal length of the fixed-focus optical system in the state of focusing on an object at infinity is set to f:

[0026] -6<f / ffocR<2 (8).

[0027] In the ninth aspect of the present invention, in the fixed-focus optical system of the fourth aspect, two focusing lens groups are arranged in the rear group that move along different trajectories during focusing.

[0028] In the tenth aspect of the present invention, in the fixed-focus optical system of the fourth aspect, a focusing lens group is arranged in the front group and the rear group respectively. The focusing lens group of the front group and the focusing lens group of the rear group move along different trajectories during focusing and satisfy the following conditional expression (9):

[0029] 0.1<|ffocF / fM|<2 (9).

[0030] Here, the combined focal length of all lenses that are closer to the object side than the most object-side focusing lens group in the fixed-focus optical system is set as fcF. The combined focal length from the lens adjacent to the image side of the previous focusing lens group to the lens adjacent to the object side of the subsequent focusing lens group is set as fM.

[0031] In the eleventh aspect of the present invention, in the fixed-focus optical system of the fourth aspect, at least one focusing lens group includes at least one specific lens.

[0032] In the 12th aspect of the present invention, in the fixed-focus optical system of the 1st aspect, the rear group includes at least one specific lens.

[0033] In the 13th aspect of the present invention, in the fixed-focus optical system of the first aspect, the front group includes at least one specific lens.

[0034] In the 14th aspect of the present invention, in the fixed-focus optical system of the first aspect, the front group and the rear group each include at least one specific lens.

[0035] The 15th aspect of the present invention, in the fixed-focus optical system of the first aspect, includes at least one joint lens, the at least one joint lens including at least one specific lens.

[0036] In the 16th aspect of the present invention, in the fixed-focus optical system of the first aspect, the rear group includes an anti-vibration group that moves in a direction intersecting the optical axis when correcting image jitter. When the focal length of the anti-vibration group is set to fIS and the focal length of the fixed-focus optical system in the state of focusing on an object at infinity is set to f, the fixed-focus optical system satisfies the following conditional expression (10):

[0037] 0.05<|fIS / f|<2 (10).

[0038] In the 17th aspect of the present invention, in the fixed-focus optical system of the 16th aspect, the vibration damping assembly includes at least one specific lens.

[0039] In the 18th aspect of the present invention, in the fixed-focus optical system of the first aspect, the maximum half-angle of view when focusing on an object at infinity is 7 degrees or less, and satisfies the following condition (11):

[0040] 0.2<Amax / TLf<0.8 (11).

[0041] Here, the maximum value of the air gap on the optical axis within the front group when focusing on an object at infinity is set to Amax. The distance on the optical axis from the lens surface closest to the object side of the front group to the lens surface closest to the image side of the front group when focusing on an object at infinity is set to TLf.

[0042] The 19th aspect of the present invention, in the fixed-focus optical system of the first aspect, when focusing on the object at the longest possible object distance, sets the angle relative to the optical axis when the principal ray of the maximum viewing angle is incident on the image plane as θc.

[0043] When the unit of θc is set to degrees, the fixed-focus optical system satisfies the following condition (12):

[0044] 0 < |θc| < 30 (12).

[0045] The 20th aspect of the present invention is a camera device having a fixed-focus optical system of any one of the 1st to 19th aspects.

[0046] In addition, the phrases “composed of” and “composed of” in this specification mean that, in addition to the constituent elements listed, it may also include lenses that do not substantially have optical power, as well as optical elements other than lenses such as apertures, filters and cover glass, and mechanism parts such as lens flanges, lens barrels, imaging elements and hand shaking correction mechanisms.

[0047] In this specification, "a group with positive optical power" means that the group as a whole has positive optical power. Similarly, "a group with negative optical power" means that the group as a whole has negative optical power. "A lens with positive optical power" has the same meaning as "positive lens." "A lens with negative optical power" has the same meaning as "negative lens." In this specification, "a group" is not limited to a structure consisting of multiple lenses; it can also be a structure consisting of only one lens.

[0048] "Single lens" refers to a single, unjoined lens. However, a compound aspherical lens (a lens (e.g., a spherical lens) and an aspherical film formed on that lens are integrated and function as a single aspherical lens) is used as a single lens and not considered a joined lens. Unless otherwise specified, the signs for the radius of curvature, optical power, and surface shape associated with lenses including aspherical surfaces are in the paraxial region. Regarding the sign of the radius of curvature, the radius of curvature of the convex surface facing the object is set to positive, and the radius of curvature of the convex surface facing the image is set to negative.

[0049] The "focal length" used in the conditional expressions is the paraxial focal length. Unless otherwise specified, the "distance on the optical axis" used in the conditional expressions is the geometric distance. Unless otherwise specified, the values ​​used in the conditional expressions are based on the d-line when focusing on an object at infinity. The "object distance" in this manual refers to the distance on the optical axis from the object to the lens surface closest to the object.

[0050] The “d-line,” “C-line,” “F-line,” and “g-line” described in this specification are bright lines. The wavelength of the d-line is considered to be 587.56 nm (nanometers), the wavelength of the C-line is considered to be 656.27 nm (nanometers), the wavelength of the F-line is considered to be 486.13 nm (nanometers), and the wavelength of the g-line is considered to be 435.84 nm (nanometers).

[0051] -Invention Effects-

[0052] According to the present invention, a fixed-focus optical system in which chromatic aberration and other aberrations are uniformly corrected, and an imaging device having the fixed-focus optical system, are provided. Attached Figure Description

[0053] Figure 1 This is a cross-sectional view corresponding to the fixed-focus optical system of Embodiment 1 and showing the structure of a fixed-focus optical system according to an embodiment.

[0054] Figure 2 It means Figure 1 The structure and cross-sectional view of the beam in various states of a fixed-focus optical system.

[0055] Figure 3These are aberration diagrams of the fixed-focus optical system in Example 1.

[0056] Figure 4 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 2.

[0057] Figure 5 These are aberration diagrams of the fixed-focus optical system in Example 2.

[0058] Figure 6 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 3.

[0059] Figure 7 These are aberration diagrams of the fixed-focus optical system in Example 3.

[0060] Figure 8 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 4.

[0061] Figure 9 These are aberration diagrams of the fixed-focus optical system in Example 4.

[0062] Figure 10 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 5.

[0063] Figure 11 These are aberration diagrams of the fixed-focus optical system in Example 5.

[0064] Figure 12 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 6.

[0065] Figure 13 These are aberration diagrams of the fixed-focus optical system in Example 6.

[0066] Figure 14 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 7.

[0067] Figure 15 These are aberration diagrams of the fixed-focus optical system in Example 7.

[0068] Figure 16 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 8.

[0069] Figure 17 These are aberration diagrams of the fixed-focus optical system in Example 8.

[0070] Figure 18 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 9.

[0071] Figure 19These are aberration diagrams of the fixed-focus optical system in Example 9.

[0072] Figure 20 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 10.

[0073] Figure 21 These are aberration diagrams of the fixed-focus optical system in Example 10.

[0074] Figure 22 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 11.

[0075] Figure 23 These are aberration diagrams of the fixed-focus optical system in Example 11.

[0076] Figure 24 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 12.

[0077] Figure 25 These are aberration diagrams of the fixed-focus optical system in Example 12.

[0078] Figure 26 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 13.

[0079] Figure 27 These are aberration diagrams of the fixed-focus optical system in Example 13.

[0080] Figure 28 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 14.

[0081] Figure 29 These are aberration diagrams of the fixed-focus optical system in Example 14.

[0082] Figure 30 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 15.

[0083] Figure 31 These are aberration diagrams of the fixed-focus optical system in Example 15.

[0084] Figure 32 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 16.

[0085] Figure 33 These are aberration diagrams of the fixed-focus optical system in Example 16.

[0086] Figure 34 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 17.

[0087] Figure 35 These are aberration diagrams of the fixed-focus optical system in Example 17.

[0088] Figure 36 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 18.

[0089] Figure 37 These are aberration diagrams of the fixed-focus optical system in Example 18.

[0090] Figure 38 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 19.

[0091] Figure 39 These are aberration diagrams of the fixed-focus optical system in Example 19.

[0092] Figure 40 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 20.

[0093] Figure 41 These are aberration diagrams of the fixed-focus optical system of Example 20.

[0094] Figure 42 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 21.

[0095] Figure 43 These are aberration diagrams of the fixed-focus optical system in Example 21.

[0096] Figure 44 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 22.

[0097] Figure 45 These are aberration diagrams of the fixed-focus optical system in Example 22.

[0098] Figure 46 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 23.

[0099] Figure 47 These are aberration diagrams of the fixed-focus optical system in Example 23.

[0100] Figure 48 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 24.

[0101] Figure 49 These are aberration diagrams of the fixed-focus optical system in Example 24.

[0102] Figure 50 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 25.

[0103] Figure 51 These are aberration diagrams of the fixed-focus optical system in Example 25.

[0104] Figure 52 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 26.

[0105] Figure 53 These are aberration diagrams of the fixed-focus optical system in Example 26.

[0106] Figure 54 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 27.

[0107] Figure 55 These are aberration diagrams of the fixed-focus optical system in Example 27.

[0108] Figure 56 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 28.

[0109] Figure 57 These are aberration diagrams of the fixed-focus optical system in Example 28.

[0110] Figure 58 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 29.

[0111] Figure 59 These are aberration diagrams of the fixed-focus optical system in Example 29.

[0112] Figure 60 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 30.

[0113] Figure 61 These are aberration diagrams of the fixed-focus optical system of Example 30.

[0114] Figure 62 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 31.

[0115] Figure 63 These are aberration diagrams of the fixed-focus optical system in Example 31.

[0116] Figure 64 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 32.

[0117] Figure 65 These are aberration diagrams of the fixed-focus optical system in Example 32.

[0118] Figure 66This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 33.

[0119] Figure 67 These are aberration diagrams of the fixed-focus optical system in Example 33.

[0120] Figure 68 This is a cross-sectional view showing the structure and beam of the fixed-focus optical system of Embodiment 34.

[0121] Figure 69 These are aberration diagrams of the fixed-focus optical system in Example 34.

[0122] Figure 70 This is a perspective view of the front side of a camera device according to one embodiment.

[0123] Figure 71 This is a perspective view of the rear side of a camera device according to one embodiment.

[0124] Symbol Explanation

[0125] 1-Fixed-focus optical system, 2-On-axis beam, 3-Beam, 3c-Primary ray, 20-Interchangeable lens, 30-Camera, 31-Camera body, 32-Shutter button, 33-Power button, 34-Operation unit, 35-Operation unit, 36-Display unit, 37-Mount, 38-Imaging element, Amax-Maximum air gap, GF-Front group, GR-Rear group, L11~L38-Lens, Sim-Image plane, St-Aperture stop, TLf-Distance, Z-Optical axis, Zp-Axis, θc-Angle, ωm-Maximum half angle of view. Detailed Implementation

[0126] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, to avoid lengthy descriptions, the "fixed-focus optical system of the present invention" will sometimes be simply referred to as the "fixed-focus optical system".

[0127] Figure 1 The figure shows a cross-sectional view of the structure of a fixed-focus optical system according to an embodiment of the present invention. Figure 2 The middle shows Figure 1 A cross-sectional view of the structure and beam of a fixed-focus optical system. Figure 2 In the image, the upper section labeled "Infinity" shows the focus on an object at infinity, while the lower section labeled "Close" shows the focus on an object at close range. Figure 2 In the diagram, beams 2 and 3 with a maximum half-angle ωm are shown as focusing on an object at infinity, and beams 3 with a maximum half-angle ωm are shown as focusing on a nearby object. Figure 1 and Figure 2In the image, the left side is the object side, and the right side is the image side. Figure 1 and Figure 2 The example shown corresponds to the fixed-focus optical system of Embodiment 1 described later. Hereinafter, reference will be made primarily to... Figure 1 Please provide an explanation.

[0128] The fixed-focus optical system of the present invention consists of a front group GF, an aperture stop St, and a rear group GR along the optical axis Z from the object side to the image side.

[0129] As an example, Figure 1 The components are configured as follows: The front group GF consists of three lenses, L11 to L13, arranged sequentially from the object side to the image side. The rear group GR consists of seven lenses, L21 to L27, arranged sequentially from the object side to the image side. Figure 1 The aperture stop St indicates the position along the optical axis, not its size or shape. This method of illustrating the aperture stop St is also used in other cross-sectional views.

[0130] The fixed-focus optical system of the present invention is configured to include at least one specific lens as described below. A specific lens is defined as a lens that satisfies the following conditions (1) and (2). Here, the refractive index of the lens included in the fixed-focus optical system relative to the d-line is set as Nd. The Abbe number of the d-line reference of the lens included in the fixed-focus optical system is set as νd.

[0131] 2.435<Nd+0.01425×νd<2.75 (1)

[0132] 15<νd<39 (2)

[0133] The material of a particular lens can be, for example, glass. The proceedings of the 49th Optical Society Annual Meeting (June 20-21, 2024, hosted by the Japan Optical Society) on pp. 40-42 describe optical glass that satisfies conditions (1) and (2) and its manufacturing method.

[0134] By ensuring that the corresponding value of condition (1) is not below the lower limit, it is beneficial to perform good correction of spherical aberration and chromatic aberration. By ensuring that the corresponding value of condition (1) is not above the upper limit, it is possible to suppress the difficulty of correcting image plane curvature.

[0135] To obtain better properties, the lower limit of conditional expression (1) is more preferably set to 2.445, further preferably 2.455, further preferably 2.468, further preferably 2.48, further preferably 2.49, further preferably 2.5, further preferably 2.51, and further preferably 2.52. To obtain better properties, the upper limit of conditional expression (1) is more preferably set to 2.74, further preferably 2.73, further preferably 2.72, further preferably 2.71, further preferably 2.7, further preferably 2.69, further preferably 2.68, and further preferably 2.67.

[0136] By ensuring that the corresponding value of condition (2) is not below the lower limit, in addition to primary color elimination, the secondary spectrum can be well corrected in color difference correction. By ensuring that the corresponding value of condition (2) is not above the upper limit, the secondary spectrum can be corrected more reliably and effectively.

[0137] To obtain better properties, the lower limit of condition (2) is more preferably set to 15.5, further preferably 16, further preferably 16.5, further preferably 16.8, further preferably 17.1, and further preferably 17.3. To obtain better properties, the upper limit of condition (2) is more preferably set to 36, further preferably 34, further preferably 33.5, further preferably 33, further preferably 32.5, and further preferably 32.

[0138] By using a specific lens that simultaneously satisfies conditions (1) and (2), it is beneficial to correct chromatic aberration, thus reducing the burden of chromatic aberration correction on each lens compared to not using a specific lens. Consequently, it is also beneficial to correct aberrations other than chromatic aberration, resulting in easy and balanced correction of chromatic aberration and other aberrations.

[0139] When the partial dispersion ratio between the g-line and F-line of the lens included in the fixed-focus optical system is set to θgF, a particular lens preferably satisfies the following condition (3).

[0140] 0.65<θgF+0.00316×νd<0.85 (3)

[0141] Furthermore, when the refractive indices of a lens relative to the g-line, F-line, and C-line are set to Ng, NF, and NC, respectively, and the partial dispersion ratio between the g-line and F-line of the lens is set to θgF, θgF is defined by the following formula.

[0142] θgF = (Ng - NF) / (NF - NC)

[0143] By ensuring that the corresponding value of condition (3) is not below the lower limit, in addition to primary color elimination, the secondary spectrum can be well corrected in color difference correction. By ensuring that the corresponding value of condition (3) is not above the upper limit, the secondary spectrum can be corrected more reliably and well.

[0144] To obtain better properties, the lower limit of condition (3) is more preferably set to 0.67, more preferably 0.675, more preferably 0.68, more preferably 0.683, more preferably 0.689, and more preferably 0.692. To obtain better properties, the upper limit of condition (3) is more preferably set to 0.8, more preferably 0.78, more preferably 0.76, more preferably 0.74, more preferably 0.73, and more preferably 0.725.

[0145] exist Figure 2 In the example, lens L11 is a specific lens. However, in the technology of this invention, it can be used with... Figure 2 Examples include configuring specific lenses in different positions, and a fixed-focus optical system may include multiple specific lenses.

[0146] For example, a fixed-focus optical system may be configured to include at least one joining lens, and the at least one joining lens of the fixed-focus optical system includes at least one specific lens. By employing a specific lens in the lenses constituting the joining lens, it is advantageous to suppress chromatic aberration. The specific lens included in the joining lens preferably satisfies the above condition (3).

[0147] The front group GF preferably includes at least one specific lens. This configuration is advantageous for correcting axial chromatic aberration. In this case, the specific lens included in the front group GF preferably satisfies the above condition (3).

[0148] A specific lens with positive optical power can be configured to be placed on the object-side of the front element GF. This specific lens is made of a high-refractive-index material; therefore, by placing a specific lens with positive optical power on the object-side of the front element GF, it is advantageous to shorten the overall optical length and correct spherical aberration. In the case of zoom optical systems, depending on the zoom setting, these advantages may not always apply, and the high refractive index may become a disadvantage; however, this is not the case in fixed-focus optical systems.

[0149] A specific lens with negative optical power can be configured to be positioned on the object-side edge of the front element GF. This specific lens is made of a high-refractive-index material; therefore, by positioning a specific lens with negative optical power on the object-side edge of the front element GF, it is advantageous to balance wide-angle magnification and distortion correction. In the case of zoom optical systems, depending on the zoom setting, these advantages may not always apply, and the high refractive index may become a disadvantage; however, this is not the case in fixed-focus optical systems.

[0150] The rear group GR preferably includes at least one specific lens. In this case, it is advantageous to correct chromatic aberration due to magnification. In this case, the specific lens included in the rear group GR preferably satisfies the above condition (3).

[0151] The front group GF and the rear group GR can each be configured to include at least one specific lens. This configuration is advantageous for correcting axial chromatic aberration and magnification chromatic aberration. In this case, both the specific lens included in the front group GF and the specific lens included in the rear group GR preferably satisfy the above condition (3).

[0152] Specific lenses can be arranged continuously. Lenses made of high-refractive-index materials, such as specific lenses, can have strong optical power even with a small difference in wall thickness between the near-axis and the periphery. Therefore, in the case of a positive specific lens, the central thickness can be reduced, and in the case of a negative specific lens, the lens adjacent to its concave side can be arranged closer together. If specific lenses with this shape and arrangement characteristics are arranged continuously without considering the sign of optical power, the continuously arranged specific lenses have strong optical power while reducing the thickness in the optical axis direction, thus facilitating miniaturization. As mentioned above, continuously arranged specific lenses generally have high assembly sensitivity, which can sometimes be disadvantageous in zoom optical systems where movable parts are located, but not in fixed-focus optical systems.

[0153] A specific lens with positive optical power can be positioned adjacent to the object side of the aperture stop St. By using a high-refractive-index material, such as the specific lens, in the positive lens and positioning it adjacent to the object side of the aperture stop St, it is advantageous to suppress the size of the aperture diameter. On the other hand, the lens adjacent to the aperture stop St typically has high sensitivity in the optical axis direction. In the case of a zoom optical system, the interplanar spacing on the object side of the aperture stop St varies considerably, thus increasing the sensitivity even further. Therefore, this configuration of the specific lens is more preferable in a fixed-focus optical system than in a zoom optical system.

[0154] A specific lens can be positioned adjacent to the image side of the aperture stop St. This configuration helps suppress chromatic aberration. In zoom optical systems, the correction for chromatic aberration varies depending on the zoom level, but this is not the case in fixed-focus optical systems.

[0155] A fixed-focus optical system preferably satisfies the following condition (4). The focal length of the front group GF, when focused on an object at infinity, is set to fF. The focal length of the rear group GR, when focused on an object at infinity, is set to fR. By ensuring that the corresponding value of condition (4) is not below the lower limit, various aberrations such as spherical aberration can be suppressed. By ensuring that the corresponding value of condition (4) is not above the upper limit, a wide angle of view is achieved.

[0156] -5<fR / fF<10 (4)

[0157] To obtain better properties, the lower limit of condition (4) is more preferably set to -3, further preferably -1.8, further preferably -1.4, further preferably -1, and further preferably -0.5. To obtain better properties, the upper limit of condition (4) is more preferably set to 7, further preferably 4, further preferably 3, further preferably 2, and further preferably 1.

[0158] Preferably, the fixed-focus optical system includes at least one focusing lens group that moves along the optical axis Z during focusing. In this case, focusing can be performed based on the distance to the object. The focusing lens group can be configured as a part of the front group GF, a part of the rear group GR, an aperture stop St and a part of the rear group GR, a part of the front group GF, an aperture stop St and a part of the rear group GR, the entire front group GF, an aperture stop St and a part of the rear group GR, or the entire fixed-focus optical system.

[0159] At least one focusing lens group preferably includes at least one specific lens. This configuration helps to suppress variations in chromatic aberration during focusing. The specific lens included in the focusing lens group preferably satisfies the above condition (3).

[0160] As an example, Figure 1 The example focusing lens group includes lenses L11–L13, aperture stop St, and lenses L21–L24. From Figure 1 The brackets and left-facing arrows above lenses L11 to L24 indicate that they are the focusing lens group and the direction of movement of the focusing lens group when focusing from an object at infinity to a closer object. The above-described illustrated method related to the focusing lens group is the same in the figures of other embodiments. Furthermore, in the figures of this application, multiple constituent elements illustrated with a bracket next to the arrow indicating movement indicate that they move integrally. "Move integrally" means moving the same amount simultaneously in the same direction.

[0161] exist Figure 1The example shown is a fixed-focus optical system comprising only one focusing lens group, but a fixed-focus optical system can also be configured to include two focusing lens groups that move along different trajectories during focusing. Furthermore, the phrase "moving along different trajectories" in relation to multiple focusing lens groups has the same meaning as "moving by changing the distance between them." By moving two focusing lens groups with different amounts of movement, it is beneficial to suppress aberration variations during focusing.

[0162] For example, it can also be configured such that two focusing lens groups are arranged in the rear group GR, which move along different trajectories during focusing. In this configuration, in addition to the effect of suppressing the aforementioned aberrations during focusing, it is also possible to suppress the diameter of the focusing lens group by placing the focusing lens group further on the image side than the front group GF.

[0163] Alternatively, it can be configured such that one focusing lens group is arranged in the front group GF and one in the rear group GR, with the focusing lens groups of the front group GF and the rear group GR moving along different trajectories during focusing. This configuration further helps to suppress aberration variations during focusing.

[0164] The fixed-focus optical system preferably satisfies the following condition (5). Here, the focal length of the focusing lens group with the strongest optical power among the focusing lens groups included in the fixed-focus optical system is set to ffocmax. The focal length of the fixed-focus optical system when focusing on an object at infinity is set to f. By ensuring that the corresponding value of condition (5) is not below the lower limit, it is beneficial to correct various aberrations. By ensuring that the corresponding value of condition (5) is not above the upper limit, the optical power of the focusing lens group can be ensured, thus making it easier to suppress the amount of movement of the focusing lens group during focusing, which is beneficial for miniaturization.

[0165] 0.2<|ffocmax / f|<3.5 (5)

[0166] To obtain better properties, the lower limit of condition (5) is more preferably set to 0.3, more preferably 0.35, more preferably 0.4, more preferably 0.45, and more preferably 0.5. To obtain better properties, the upper limit of condition (5) is more preferably set to 3, more preferably 2.5, more preferably 2, more preferably 1.5, and more preferably 1.

[0167] The fixed-focus optical system preferably satisfies the following condition (7). Here, the combined focal length of all lenses that are closer to the object side than the focal lens group closest to the object side in the fixed-focus optical system is set to fcF. The focal length of the fixed-focus optical system when focusing on an object at infinity is set to f. By ensuring that the corresponding value of condition (7) is not below the lower limit, the negative combined optical power of all lenses that are closer to the object side than the focal lens group closest to the object side will not become too strong, thus suppressing the increase in the total optical length and thus helping to ensure the amount of peripheral light. By ensuring that the corresponding value of condition (7) is not above the upper limit, the positive combined optical power of all lenses that are closer to the object side than the focal lens group closest to the object side will not become too strong, thus helping to correct distortion aberrations and image plane curvature.

[0168] -2<f / ffocF<6 (7)

[0169] To obtain better properties, the lower limit of condition (7) is more preferably set to -1.5, further preferably -1.2, further preferably -0.9, further preferably -0.7, further preferably -0.5, further preferably -0.4, and further preferably -0.3. To obtain better properties, the upper limit of condition (7) is more preferably set to 4.5, further preferably 3.5, further preferably 2.5, further preferably 2, further preferably 1.5, further preferably 1.2, and further preferably 0.9.

[0170] The fixed-focus optical system preferably satisfies the following condition (8). Here, the combined focal length of all lenses further to the image side than the most image-side focusing lens group included in the fixed-focus optical system is set to ffocR. The focal length of the fixed-focus optical system when focusing on an object at infinity is set to f. By ensuring that the corresponding value of condition (8) is not below the lower limit, the negative combined optical power of all lenses further to the image side than the aforementioned most image-side focusing lens group will not become too strong, thus facilitating the correction of magnification chromatic aberration. By ensuring that the corresponding value of condition (8) is not above the upper limit, the positive combined optical power of all lenses further to the image side than the aforementioned most image-side focusing lens group will not become too strong, thus facilitating the correction of distortion aberration and image plane curvature.

[0171] -6<f / ffocR<2 (8)

[0172] To obtain better properties, the lower limit of condition (8) is more preferably set to -4.5, further preferably -3.5, further preferably -2.5, further preferably -2, further preferably -1.5, further preferably -1.2, and further preferably -0.9. To obtain better properties, the upper limit of condition (8) is more preferably set to 1.5, further preferably 1.2, further preferably 0.9, further preferably 0.7, further preferably 0.5, further preferably 0.4, and further preferably 0.3.

[0173] In a fixed-focus optical system comprising two focusing lens groups, the fixed-focus optical system preferably satisfies the following condition (6). Here, the focal length of the object-side focusing lens group is set to ff1, and the focal length of the image-side focusing lens group is set to ff2. By ensuring that the corresponding value of condition (6) is not below the lower limit, the optical power of the object-side focusing lens group will not become excessively strong, thus making it easy to correct astigmatism. By ensuring that the corresponding value of condition (6) is not above the upper limit, the optical power of the object-side focusing lens group will not become excessively weak, thus making it easy to correct image plane curvature.

[0174] 0.1 < |ff1 / ff2| < 10 (6)

[0175] To obtain better properties, the lower limit of condition (6) is more preferably set to 0.2, more preferably 0.3, more preferably 0.4, more preferably 0.45, and more preferably 0.5. To obtain better properties, the upper limit of condition (6) is more preferably set to 5, more preferably 4, more preferably 3, more preferably 2, and more preferably 1.

[0176] In a fixed-focus optical system, where one focusing lens group is configured in each of the front group GF and the rear group GR, and the focusing lens groups of the front group GF and the rear group GR move along different trajectories during focusing, the following condition (9) is preferably satisfied. Here, the combined focal length of all lenses that are closer to the object side than the focusing lens group closest to the object side in the fixed-focus optical system is set to fcF. The combined focal length from the lens adjacent to the image side of the focusing lens group in the front group GF to the lens adjacent to the object side of the focusing lens group in the rear group GR is set to fM. That is, the combined focal length of all lenses located between the focusing lens group in the front group GF and the focusing lens group in the rear group GR is set to fM. By ensuring that the corresponding value of condition (9) does not fall below the lower limit value, the combined optical power of all lenses that are closer to the object side than the aforementioned focusing lens group closest to the object side will not become too strong, thus facilitating the correction of various aberrations. By ensuring that the corresponding value of condition (9) does not exceed the upper limit, it is possible to suppress the enlargement of the lens that is closer to the object side than the above-mentioned focusing lens group that is closest to the object side.

[0177] 0.1 < |ffocF / fM| < 2 (9)

[0178] To obtain better properties, the lower limit of condition (9) is more preferably set to 0.4, further preferably 0.5, further preferably 0.6, and further preferably 0.65. To obtain better properties, the upper limit of condition (9) is more preferably set to 1.2, further preferably 1, further preferably 0.9, and further preferably 0.85.

[0179] In a fixed-focus optical system, the rear group GR can be configured to include an anti-vibration group that moves in a direction intersecting the optical axis Z during image jitter correction. By configuring the anti-vibration group in the rear group GR, the diameter of the anti-vibration group can be easily suppressed. The anti-vibration group can be configured to include at least one specific lens. In this case, it is beneficial to suppress chromatic aberration variations during image jitter correction. The specific lens included in the anti-vibration group preferably satisfies the above condition (3).

[0180] In the structure of the rear GR including the anti-vibration group, the fixed-focus optical system preferably satisfies the following condition (10). Here, the focal length of the anti-vibration group is set to fIS. The focal length of the fixed-focus optical system in the state of focusing on an object at infinity is set to f. By ensuring that the corresponding value of condition (10) is not below the lower limit, it is beneficial to correct various aberrations. By ensuring that the corresponding value of condition (10) is not above the upper limit, the optical power of the anti-vibration group can be ensured, thus making it easier to suppress the amount of movement of the anti-vibration group during image jitter correction, which is beneficial for miniaturization.

[0181] 0.05 < |fIS / f| < 2 (10)

[0182] To obtain better properties, the lower limit of condition (10) is more preferably set to 0.1, more preferably 0.15, more preferably 0.2, more preferably 0.25, and more preferably 0.3. To obtain better properties, the upper limit of condition (10) is more preferably set to 1.5, more preferably 1, more preferably 0.7, more preferably 0.5, and more preferably 0.4.

[0183] In a fixed-focus optical system, where the maximum half-angle of view is 7 degrees or less when focusing on an object at infinity, the following condition (11) is preferably satisfied. Here, the maximum value of the air gap on the optical axis within the front group GF when focusing on an object at infinity is set as Amax. The distance on the optical axis from the lens surface closest to the object side of the front group GF to the lens surface closest to the image side of the front group GF when focusing on an object at infinity is set as TLf. Figure 22 The structure of a fixed-focus optical system in Embodiment 11, which has a maximum half-angle of 7 degrees or less when focusing on an object at infinity, is shown. As an example, the maximum value of the air gap Amax and the distance TLf are shown. By ensuring that the corresponding value of conditional expression (11) is not below the lower limit, it is possible to suppress the overall weight of the optical system from becoming too heavy. By ensuring that the corresponding value of conditional expression (11) is not above the upper limit, spherical aberration and on-axis chromatic aberration are easily suppressed.

[0184] 0.2 < Amax / TLf < 0.8 (11)

[0185] To obtain better properties, the lower limit of condition (11) is more preferably set to 0.3, more preferably 0.4, and even more preferably 0.45. To obtain better properties, the upper limit of condition (11) is more preferably set to 0.7, more preferably 0.65, and even more preferably 0.6.

[0186] A fixed-focus optical system preferably satisfies the following condition (12). Here, when focusing on an object at the longest object distance that the fixed-focus optical system can focus on, the angle of the principal ray of the maximum angle of view incident on the image plane Sim relative to the optical axis Z is defined as θc. The unit of θc is degrees. As an example, in Figure 1 In a fixed-focus optical system, the longest object distance that can be focused is infinite. However, condition (12) can also be applied to optical systems where the longest object distance that can be focused is a finite value. As an example, in Figure 2 The upper section shows the principal ray 3c at the maximum angle of view and the aforementioned angle θc. In Figure 2In the diagram, the axis Zp, which is parallel to the optical axis Z, is represented by a double-dotted line. By ensuring that the corresponding value of condition (12) is not below the lower limit, it is easy to reduce the diameter of the lens near the image plane and shorten the total optical length. By ensuring that the corresponding value of condition (12) is not above the upper limit, it is possible to suppress the reduction in the amount of light incident on the image plane Sim.

[0187] 0 < |θc| < 30 (12)

[0188] To obtain better properties, the lower limit of condition (12) is more preferably set to 0.4, further preferably 0.8, further preferably 1.2, further preferably 1.6, further preferably 2, further preferably 2.3, and further preferably 2.5. To obtain better properties, the upper limit of condition (12) is more preferably set to 26, further preferably 23, further preferably 20, further preferably 17, further preferably 14, further preferably 12, and further preferably 10.

[0189] A fixed-focus optical system preferably satisfies the following condition (13). Here, the paraxial radius of curvature of the object-side surface of the lens closest to the object in the front group GF is set as L1f. The paraxial radius of curvature of the image-side surface of the lens closest to the object in the front group GF is set as L1r. Condition (13) is a formula that specifies the shape factor of the lens. By ensuring that the corresponding value of condition (13) is not below the lower limit, astigmatism is easily corrected. By ensuring that the corresponding value of condition (13) is not above the upper limit, spherical aberration is easily and well corrected, and the optical power of the lens does not become too weak, thus facilitating wide-angle magnification.

[0190] -3<(L1r-L1f) / (L1r+L1f)<1 (13)

[0191] To obtain better properties, the lower limit of condition (13) is more preferably set to -2, more preferably -1, more preferably -0.7, and more preferably -0.5. To obtain better properties, the upper limit of condition (13) is more preferably set to 0.8, more preferably 0.6, more preferably 0.4, and more preferably 0.2.

[0192] When the open F-value is set to Fno when focusing on an object at infinity, the fixed-focus optical system preferably satisfies the following condition (14). By ensuring that the corresponding value of condition (14) is not below the lower limit, it is easy to correct various aberrations and shorten the total optical length. By ensuring that the corresponding value of condition (14) is not above the upper limit, the brightness of the optical system can be ensured.

[0193] 0.8 < Fno < 3 (14)

[0194] To obtain better properties, the lower limit of condition (14) is more preferably set to 0.9, more preferably 0.95, more preferably 1, more preferably 1.05, and more preferably 1.1. To obtain better properties, the upper limit of condition (14) is more preferably set to 2.4, more preferably 2.1, more preferably 1.8, more preferably 1.5, and more preferably 1.3.

[0195] When the maximum half-angle of a fixed-focus optical system focused on an object at infinity is set to ωm, the fixed-focus optical system preferably satisfies the following condition (15). The unit of ωm is degrees. As an example, in Figure 2 The upper section shows the maximum half-angle of view ωm mentioned above. By ensuring that the corresponding value of condition (15) is not below the lower limit, a wide angle of view can be ensured, thus enabling it to have high added value as an imaging lens system. By ensuring that the corresponding value of condition (15) is not above the upper limit, a balance between optical performance and miniaturization can be easily achieved.

[0196] 20<ωm<50 (15)

[0197] To obtain better properties, the lower limit of condition (15) is more preferably set to 21, more preferably 22, more preferably 23, more preferably 24, and more preferably 25. To obtain better properties, the upper limit of condition (15) is more preferably set to 47, more preferably 44, more preferably 41, more preferably 38, and more preferably 36.

[0198] in addition, Figure 1 The example shown is one illustration; the fixed-focus optical system of the present invention can be modified in various ways without departing from the spirit of the invention. For example, the number and structure of the lenses included in the front group GF, the rear group GR, and the focusing lens group can be varied. Figure 1 The examples are different.

[0199] The front group GF can be configured to sequentially include a first lens component with positive optical power and a second lens component with positive optical power from the object side to the image side. In this specification, a single lens or a combined lens is considered as one lens component. In the configuration where the front group GF sequentially includes the first and second lens components from the object side to the image side, the fixed-focus optical system preferably satisfies the following condition (16). Here, the combined focal length of the first and second lens components is set to fp2. By ensuring that the corresponding value of condition (16) is not below the lower limit, it is beneficial to correct spherical aberration. By ensuring that the corresponding value of condition (16) is not above the upper limit, overcorrection of spherical aberration can be suppressed.

[0200] 0.8 < f / fp2 < 10 (16)

[0201] To obtain better properties, the lower limit of condition (16) is more preferably set to 1, more preferably 1.2, more preferably 1.4, more preferably 1.6, and more preferably 1.8. To obtain better properties, the upper limit of condition (16) is more preferably set to 8, more preferably 6, more preferably 5, more preferably 4, and more preferably 3.

[0202] The front lens group (GF) can be configured to sequentially include a first lens component with positive optical power, a second lens component with positive optical power, and a third lens component with positive optical power, arranged from the object side to the image side. In the structure of the front lens group (GF) sequentially including the aforementioned first lens component, second lens component, and third lens component from the object side to the image side, the fixed-focus optical system preferably satisfies the following condition (17). Here, the combined focal length of the aforementioned first lens component, second lens component, and third lens component is set to fp3. By ensuring that the corresponding value of condition (17) is not below the lower limit, it is beneficial to correct spherical aberration. By ensuring that the corresponding value of condition (17) is not above the upper limit, it is possible to suppress overcorrection of spherical aberration.

[0203] 1 < f / fp3 < 10 (17)

[0204] To obtain better properties, the lower limit of condition (17) is more preferably set to 1.1, more preferably 1.2, more preferably 1.3, more preferably 1.4, and more preferably 1.5. To obtain better properties, the upper limit of condition (17) is more preferably set to 7.5, more preferably 5.5, more preferably 4, more preferably 3, and more preferably 2.

[0205] The front group GF can be configured to sequentially include a fourth lens component with negative optical power and a fifth lens component with negative optical power from the object side to the image side. In the structure of the front group GF sequentially including the aforementioned fourth lens component and fifth lens component from the object side to the image side, the fixed-focus optical system preferably satisfies the following condition (18). Here, the combined focal length of the aforementioned fourth lens component and fifth lens component is set to fn2. By ensuring that the corresponding value of condition (18) is not below the lower limit, it is beneficial to effectively correct chromatic aberration. By ensuring that the corresponding value of condition (18) is not above the upper limit, it is beneficial to effectively correct various aberrations such as distortion aberration and image plane curvature.

[0206] -4<f / fn2<-0.2 (18)

[0207] To obtain better properties, the lower limit of condition (18) is more preferably set to -3, further preferably -2, further preferably -1.5, further preferably -1.3, and further preferably -1.1. To obtain better properties, the upper limit of condition (18) is more preferably set to -0.4, further preferably -0.5, further preferably -0.55, further preferably -0.6, and further preferably -0.65.

[0208] The front group GF can be configured to sequentially include a fourth lens component with negative optical power, a fifth lens component with negative optical power, and a sixth lens component with negative optical power, from the object side to the image side. In the structure of the front group GF sequentially including the aforementioned fourth, fifth, and sixth lens components from the object side to the image side, the fixed-focus optical system preferably satisfies the following condition (19). Here, the combined focal length of the aforementioned fourth, fifth, and sixth lens components is set to fn3. By ensuring that the corresponding value of condition (19) is not below the lower limit, it is beneficial to effectively correct magnification chromatic aberration. By ensuring that the corresponding value of condition (19) is not above the upper limit, it is beneficial to effectively correct various aberrations such as distortion aberration and image plane curvature.

[0209] -4 < f / fn3 < -0.2 (19)

[0210] To obtain better properties, the lower limit of condition (19) is more preferably set to -3, further preferably -2, further preferably -1.5, further preferably -1.3, and further preferably -1.1. To obtain better properties, the upper limit of condition (19) is more preferably set to -0.4, further preferably -0.5, further preferably -0.55, further preferably -0.6, and further preferably -0.65.

[0211] When the maximum magnification is set to β, the fixed-focus optical system preferably satisfies the following condition (20). The maximum magnification is the magnification when photographing the nearest object (i.e., the object at the shortest object distance that can be focused). By ensuring that the corresponding value of condition (20) is not below the lower limit, the narrowing of the photographic area of ​​the optical system can be suppressed, thus ensuring the added value of being preferred as an imaging lens system. By ensuring that the corresponding value of condition (20) is not above the upper limit, the amount of movement of the focusing lens group during focusing can be suppressed, thus contributing to the miniaturization of the optical system.

[0212] 0.05 < |β| < 1.1 (20)

[0213] To obtain better properties, the lower limit of condition (20) is more preferably set to 0.09, more preferably 0.12, more preferably 0.15, more preferably 0.18, more preferably 0.21, more preferably 0.24, and more preferably 0.27. To obtain better properties, the upper limit of condition (20) is more preferably set to 1, more preferably 0.9, more preferably 0.8, more preferably 0.75, more preferably 0.7, more preferably 0.67, and more preferably 0.65.

[0214] The above-mentioned preferred structures and achievable structures can be combined arbitrarily within the scope of non-conflict, and are preferably adopted selectively and appropriately according to the required specifications.

[0215] As an example, a preferred embodiment of the fixed-focus optical system of the present invention is a specific lens consisting of a front group GF, an aperture stop St and a rear group GR arranged sequentially from the object side to the image side, and including at least one lens that satisfies the above conditions (1) and (2).

[0216] Next, embodiments of the fixed-focus optical system of the present invention will be described with reference to the accompanying drawings. Furthermore, the reference numerals on each lens and group of lenses in the cross-sectional views of each embodiment are used independently for each embodiment to avoid complexity in the description and drawings caused by an increase in the number of reference numerals. Therefore, even if the same reference numerals are used in the drawings of different embodiments, the structures are not necessarily the same.

[0217] [Example 1]

[0218] A cross-sectional view of the structure of the fixed-focus optical system of Example 1 is shown in Figure 1 The illustrated method and structure are as described above, therefore some repetitive descriptions are omitted here. The fixed-focus optical system, from the object side to the image side, consists of a front group GF with positive optical power, an aperture stop St, and a rear group GR with positive optical power. The fixed-focus optical system includes only one focusing lens group. The focusing lens group consists of lenses L11–L13, an aperture stop St, and lenses L21–L24, which move towards the object side when focusing from an infinity object to a closer object.

[0219] Regarding the fixed-focus optical system of Example 1, the basic lens data is shown in Table 1, the specifications and variable surface spacing are shown in Table 2, and the aspherical coefficients are shown in Table 3.

[0220] The following table contains basic lens data. The "Sn" column shows the surface number when the object-side surface is designated as surface 1, and the number increases by one as it moves towards the image-side assembly. The "R" column shows the radius of curvature of each surface. The "D" column shows the surface spacing along the optical axis of each surface and its image-side neighbor. The "Nd" column shows the refractive index of each lens relative to the d-line. The "νd" column shows the Abbe number of each lens based on the d-line. The "θgF" column shows the partial dispersion ratio between the g-line and F-line of each lens. The "ED" column shows the effective diameter of each surface.

[0221] Including the table of embodiments described later, the "Material" column in the table of basic lens data is as follows. The "Material" column for a specific lens lists any one of "N231 glass," "N216 glass," and "N200 glass." As "N231 glass," "N216 glass," and "N200 glass," the glass described in the proceedings of the 49th Optical Society Annual Meeting (June 20-21, 2024, organized by the Optical Society of Japan) pp. 40-42 can be used.

[0222] For lenses other than specific ones, in the "Materials" column, resin lenses are listed as "Plastic." For other lenses, the material name is listed before the period (."), followed by the name of the manufacturing company. The manufacturing company names are briefly shown in the table below: "OHARA" represents OHARA INC.; "CDGM" represents Chengdu Guangming Optoelectronics Co., Ltd.; "HOYA" represents HOYACorporation; "HIKARI" represents HIKARI GLASS Co., Ltd.; "SUMITA" represents SUMITA OPTICALGLASS, Inc.; and "NHG" represents Hubei Xinhua Optoelectronic Information Materials Co., Ltd.

[0223] In the table of basic lens data, the sign of the radius of curvature of the convex surface facing the object is set to positive, and the sign of the radius of curvature of the convex surface facing the image is set to negative. The surface number and the term (St) are recorded in the column corresponding to the aperture stop St. The bottom column of column D in the table shows the interval between the image-side surface and the image plane Sim. Regarding the variable surface interval during focusing, the notation DD[ ] is used, and the object-side surface number of this interval is marked in [ ] and recorded in the surface interval column.

[0224] Table 2 shows the focal length, back focal length, open F-number, maximum field of view, and variable plane spacing of the fixed-focus optical system, using the d-line as a reference. The [°] in the maximum field of view column indicates the unit as degrees. Table 2 also shows the values ​​for focusing on an object at infinity in the "Infinity" column and the values ​​for focusing on a close object at -0.1x magnification in the "Close -0.1x" column. In the specifications table, the magnification is indicated by "x" after the term "close" when focusing on the nearest object.

[0225] In the basic lens data, aspherical surfaces are marked with an asterisk (*), and the paraxial radius of curvature is recorded in the aspherical surface radius of curvature column. Table 3 shows the aspherical surface number in row Sn, and the aspherical coefficient values ​​for each aspherical surface in rows KA and Am. Furthermore, m in Am is an integer greater than or equal to 3, and varies depending on the surface. For example, in surface 13 of Example 1, m = 4, 6, 8, 10, 12, 14, 16, 18. The "E±n" (n: integer) values ​​for the aspherical coefficients in Table 3 mean "×10" ±n KA and Am are the aspheric coefficients in the aspheric formula expressed by the following equation.

[0226] Zd=C×h 2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+ΣAm×h m

[0227] in,

[0228] Zd: Aspherical depth (the length of the perpendicular line from a point on the aspherical surface at height h to a plane tangent to the vertex of the aspherical surface and perpendicular to the optical axis Z).

[0229] h: Height (distance from the optical axis Z to the lens surface);

[0230] C: The reciprocal of the paraxial radius of curvature;

[0231] KA, Am: Aspheric coefficients

[0232] In aspherical form, Σ represents the sum related to m.

[0233] In the data in each table, degrees are used as the unit for angles and millimeters as the unit for lengths. However, optical systems can use both magnified and reduced scales, so other appropriate units can also be used. Furthermore, the tables shown below contain values ​​rounded to a predetermined number of decimal places.

[0234]

[0235]

[0236]

[0237] Figure 3 The diagram shows the aberrations of the fixed-focus optical system of Embodiment 1. Figure 3 In the middle, from left to right, are shown spherical aberration, astigmatism, distortion aberration, and magnification chromatic aberration. Figure 3 In the diagram, the upper section marked "Infinity" shows aberration diagrams for focusing on an object at infinity, and the lower section marked "Close Distance -0.1x" shows aberration diagrams for focusing on a close object at a magnification of -0.1x. Thus, the lower section of the aberration diagram shows aberrations at the magnifications shown in the specification table. In the spherical aberration diagram, aberrations along the d-line, C-line, F-line, and g-line are shown with solid lines, long dashed lines, short dashed lines, and single-dot dashed lines, respectively. In the astigmatism diagram, aberrations along the d-line in the sagittal direction are shown with solid lines, and aberrations along the d-line in the meridional direction are shown with short dashed lines. In the distortion aberration diagram, aberrations along the d-line are shown with solid lines. In the magnification chromatic aberration diagram, aberrations along the C-line, F-line, and g-line are shown with long dashed lines, short dashed lines, and single-dot dashed lines, respectively. In the spherical aberration diagram, the open F-value is shown after "FNo.=". In other aberration diagrams, the value of the maximum half-angle is shown after “ω=".

[0238] Unless otherwise specified, the notation, meaning, recording method and illustration method of the data related to Embodiment 1 above are basically the same in the following embodiments, so repeated descriptions are omitted below.

[0239] [Example 2]

[0240] The structure and cross-sectional view of the fixed-focus optical system of Example 2 are shown below. Figure 4 A fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of three lenses (L11-L13) from the object side to the image side. The rear group (GR) consists of seven lenses (L21-L27) from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group consists of lenses L11-L13, the aperture stop (St), and lenses L21-L24, and moves towards the object side when focusing from an infinity object to a closer object.

[0241] Regarding the fixed-focus optical system of Example 2, the basic lens data is shown in Table 4, the specifications and variable surface spacing are shown in Table 5, and the various aberrations are illustrated in Table 6. Figure 5 .

[0242]

[0243]

[0244] [Example 3]

[0245] The structure and cross-sectional view of the fixed-focus optical system of Example 3 are shown in the figure. Figure 6 The fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of four lenses (L11-L14) arranged sequentially from the object side to the image side. The rear group (GR) consists of eight lenses (L21-L28) arranged sequentially from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group consists of lenses L11-L14, an aperture stop (St), and lenses L21-L22, and moves towards the object side when focusing from an infinity object to a closer object. The image stabilization group includes lenses L25-L26. Additionally, in... Figure 6 In the diagram, parentheses and upward-pointing arrows are marked on the lenses corresponding to the vibration damping group. The above-described illustration method related to the vibration damping group is also the same in the figures of other embodiments.

[0246] Regarding the fixed-focus optical system of Example 3, the basic lens data is shown in Table 6, the specifications and variable surface spacing are shown in Table 7, the aspherical coefficients are shown in Table 8, and the various aberrations are illustrated in Table 9. Figure 7 middle.

[0247]

[0248]

[0249]

[0250] [Example 4]

[0251] The structure and cross-sectional view of the fixed-focus optical system of Example 4 are shown in the figure. Figure 8 The fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of four lenses (L11-L14) from the object side to the image side. The rear group (GR) consists of eight lenses (L21-L28) from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group consists of lenses L11-L14, an aperture stop (St), and lenses L21-L22, and moves towards the object side when focusing from an infinity object to a closer object. The image stabilization group includes lenses L25-L26.

[0252] Regarding the fixed-focus optical system of Example 4, the basic lens data is shown in Table 9, the specifications and variable surface spacing are shown in Table 10, the aspherical coefficients are shown in Table 11, and the various aberrations are illustrated in Table 11. Figure 9 middle.

[0253]

[0254]

[0255]

[0256] [Example 5]

[0257] The structure and cross-sectional view of the fixed-focus optical system of Example 5 are shown in the figure. Figure 10 A fixed-focus optical system consists of, from the object side to the image side, a front group GF (positive optical power), an aperture stop St, and a rear group GR (positive optical power). The front group GF comprises eight lenses, L11 to L18, from the object side to the image side. The rear group GR comprises six lenses, L21 to L26, from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group, comprising lenses L21 to L24, moves towards the object side when focusing from an infinity object to a closer object.

[0258] Regarding the fixed-focus optical system of Example 5, the basic lens data is shown in Table 12, the specifications and variable surface spacing are shown in Table 13, the aspherical coefficients are shown in Table 14, and the various aberrations are illustrated in Table 15. Figure 11 middle.

[0259]

[0260]

[0261]

[0262] [Example 6]

[0263] The structure and cross-sectional view of the fixed-focus optical system of Example 6 are shown in the figure. Figure 12 The fixed-focus optical system consists of a front group (GF) with negative optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of three lenses (L11-L13) from the object side to the image side. The rear group (GR) consists of seven lenses (L21-L27) from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group, composed of lens L26, moves towards the object side when focusing from an infinity object to a closer object.

[0264] Regarding the fixed-focus optical system of Example 6, the basic lens data is shown in Table 15, the specifications and variable surface spacing are shown in Table 16, the aspherical coefficients are shown in Table 17, and the various aberrations are illustrated in Table 18. Figure 13 middle.

[0265]

[0266]

[0267]

[0268] [Example 7]

[0269] The structure and cross-sectional view of the fixed-focus optical system of Example 7 are shown in [the figure]. Figure 14 A fixed-focus optical system consists of, from the object side to the image side, a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power. The front group (GF) consists of seven lenses (L11-L17) from the object side to the image side. The rear group (GR) consists of eight lenses (L21-L28) from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group, composed of lenses L21-L26, moves towards the object side when focusing from an infinity object to a closer object.

[0270] Regarding the fixed-focus optical system of Example 7, the basic lens data is shown in Table 18, the specifications and variable surface spacing are shown in Table 19, the aspherical coefficients are shown in Table 20, and the various aberrations are illustrated in Table 18. Figure 15 middle.

[0271]

[0272]

[0273]

[0274] [Example 8]

[0275] The structure and cross-sectional view of the fixed-focus optical system of Example 8 are shown in the figure. Figure 16 A fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) comprises six lenses, L11 through L16, arranged sequentially from the object side to the image side. The rear group (GR) comprises six lenses, L21 through L26, arranged sequentially from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group, composed of lenses L21 through L23, moves towards the object side when focusing from an infinity object to a closer object.

[0276] Regarding the fixed-focus optical system of Example 8, the basic lens data is shown in Table 21, the specifications and variable surface spacing are shown in Table 22, the aspherical coefficients are shown in Table 23, and the various aberrations are illustrated in Table 24. Figure 17 In the table of basic lens data, the surface numbers corresponding to the composite aspherical surface of the composite aspherical lens are marked with an asterisk (*).

[0277]

[0278]

[0279]

[0280] [Example 9]

[0281] The structure and cross-sectional view of the fixed-focus optical system of Example 9 are shown in the figure. Figure 18 A fixed-focus optical system consists of, from the object side to the image side, a front group GF (positive optical power), an aperture stop St, and a rear group GR (positive optical power). The front group GF comprises six lenses, L11 to L16, from the object side to the image side. The rear group GR comprises eight lenses, L21 to L28, from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group, composed of lenses L21 and L22, moves towards the image side when focusing from an object at infinity to a closer object.

[0282] Regarding the fixed-focus optical system of Example 9, the basic lens data is shown in Table 24, the specifications and variable surface spacing are shown in Table 25, and the various aberrations are illustrated in Table 26. Figure 19 .

[0283]

[0284]

[0285] [Example 10]

[0286] The structure and cross-sectional view of the fixed-focus optical system of Example 10 are shown in the figure. Figure 20 A fixed-focus optical system consists of, from the object side to the image side, a front group (GF) with negative optical power, an aperture stop (St), and a rear group (GR) with positive optical power. The front group (GF) consists of seven lenses, L11 through L17, from the object side to the image side. The rear group (GR) consists of seven lenses, L21 through L27, from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group, composed of lenses L21 through L26, moves towards the object side when focusing from an infinity object to a closer object.

[0287] Regarding the fixed-focus optical system of Example 10, basic lens data are shown in Table 26, specifications and variable surface spacing are shown in Table 27, aspherical coefficients are shown in Tables 28A and 28B, and various aberrations are illustrated in Table 28A. Figure 21 middle.

[0288]

[0289]

[0290]

[0291]

[0292] [Example 11]

[0293] The structure and cross-sectional view of the fixed-focus optical system of Example 11 are shown in the figure. Figure 22 The fixed-focus optical system consists of, from the object side to the image side, a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with negative optical power. The front group (GF) consists of seven lenses (L11-L17) from the object side to the image side. The rear group (GR) consists of eighteen lenses (L21-L38) from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. The focusing lens group, composed of lens L21, moves towards the image side when focusing from an object at infinity to a closer object. The image stabilization group consists of lenses L24-L26.

[0294] Regarding the fixed-focus optical system of Example 11, basic lens data are shown in Tables 29A and 29B, specifications and variable surface spacing are shown in Table 30, and various aberrations are illustrated in... Figure 23 To avoid making one table too long, the basic lens data is presented in two separate tables.

[0295]

[0296]

[0297]

[0298] [Example 12]

[0299] The structure and cross-sectional view of the fixed-focus optical system of Example 12 are shown in the figure. Figure 24A fixed-focus optical system consists of, from the object side to the image side, a front group GF (positive optical power), an aperture stop St, and a rear group GR (positive optical power). The front group GF consists of five lenses, L11 to L15, from the object side to the image side. The rear group GR consists of eight lenses, L21 to L28, from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group includes the aperture stop St and lenses L21 to L27, which move towards the object side when focusing from an infinity object to a closer object.

[0300] Regarding the fixed-focus optical system of Example 12, the basic lens data is shown in Table 31, the specifications and variable surface spacing are shown in Table 32, the aspherical coefficients are shown in Table 33, and the various aberrations are illustrated in Table 34. Figure 25 middle.

[0301]

[0302]

[0303]

[0304] [Example 13]

[0305] The structure and cross-sectional view of the fixed-focus optical system of Example 13 are shown in the figure. Figure 26 A fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of five lenses (L11-L15) arranged sequentially from the object side to the image side. The rear group (GR) consists of nine lenses (L21-L29) arranged sequentially from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group consists of lenses L13-L15, an aperture stop (St), and lenses L21-L25, and moves towards the object side when focusing from an infinity object to a closer object.

[0306] Regarding the fixed-focus optical system of Example 13, the basic lens data are shown in Table 34, the specifications and variable surface spacing are shown in Table 35, the aspherical coefficients are shown in Table 36, and the various aberrations are illustrated in Table 37. Figure 27 middle.

[0307]

[0308]

[0309]

[0310] [Example 14]

[0311] The structure and cross-sectional view of the fixed-focus optical system of Example 14 are shown in the figure. Figure 28 A fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of five lenses (L11-L15) arranged sequentially from the object side to the image side. The rear group (GR) consists of eight lenses (L21-L28) arranged sequentially from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group consists of lenses L13-L15, an aperture stop (St), and lenses L21-L25, and moves towards the object side when focusing from an infinity object to a closer object.

[0312] Regarding the fixed-focus optical system of Example 14, the basic lens data is shown in Table 37, the specifications and variable surface spacing are shown in Table 38, the aspherical coefficients are shown in Table 39, and the various aberrations are illustrated in Table 30. Figure 29 middle.

[0313]

[0314]

[0315]

[0316] [Example 15]

[0317] The structure and cross-sectional view of the fixed-focus optical system of Example 15 are shown in the figure. Figure 30 The fixed-focus optical system consists of, from the object side to the image side, a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with negative optical power. The front group (GF) consists of seven lenses (L11-L17) from the object side to the image side. The rear group (GR) consists of fourteen lenses (L21-L34) from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. The focusing lens group includes lens L16, which moves towards the image side when focusing from an infinity object to a closer object. The image stabilization group consists of lenses L23-L25.

[0318] Regarding the fixed-focus optical system of Example 15, the basic lens data is shown in Table 40, the specifications and variable surface spacing are shown in Table 41, and the various aberrations are illustrated in Table 42. Figure 31 middle.

[0319]

[0320] [Example 16]

[0321] The structure and cross-sectional view of the fixed-focus optical system of Example 16 are shown in the figure. Figure 32The fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of seven lenses, L11 through L17, arranged sequentially from the object side to the image side. The rear group (GR) consists of seven lenses, L21 through L27, arranged sequentially from the object side to the image side. The fixed-focus optical system includes two focusing lens groups. The focusing lens group on the object side consists of lenses L22 through L25, and the focusing lens group on the image side consists of lens L26. When focusing from an object at infinity to a closer object, the focusing lens groups on the object side and the image side change their spacing and move towards the object side.

[0322] Regarding the fixed-focus optical system of Example 16, the basic lens data is shown in Table 42, the specifications and variable surface spacing are shown in Table 43, the aspherical coefficients are shown in Tables 44A and 44B, and the various aberrations are illustrated in Table 44A. Figure 33 middle.

[0323]

[0324]

[0325]

[0326]

[0327] [Example 17]

[0328] The structure and cross-sectional view of the fixed-focus optical system of Example 17 are shown in the figure. Figure 34 The fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of three lenses (L11-L13) from the object side to the image side. The rear group (GR) consists of seven lenses (L21-L27) from the object side to the image side. The fixed-focus optical system includes two focusing lens groups. The focusing lens group on the object side consists of lenses L21-L24, and the focusing lens group on the image side consists of lenses L25-L26. When focusing from an object at infinity to a closer object, the focusing lens groups on the object side and the image side change their spacing and move towards the object side.

[0329] Regarding the fixed-focus optical system of Example 17, the basic lens data are shown in Table 45, the specifications and variable surface spacing are shown in Table 46, the aspherical coefficients are shown in Table 47, and the various aberrations are illustrated in Table 48. Figure 35 In the table of basic lens data, the surface numbers corresponding to the composite aspherical surface of the composite aspherical lens are marked with an asterisk (*).

[0330]

[0331]

[0332]

[0333] [Example 18]

[0334] The structure and cross-sectional view of the fixed-focus optical system of Example 18 are shown in the figure. Figure 36 The fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of seven lenses (L11-L17) from the object side to the image side. The rear group (GR) consists of four lenses (L21-L24) from the object side to the image side. The fixed-focus optical system includes two focusing lens groups. The focusing lens group on the object side consists of lens L21, and the focusing lens group on the image side consists of lens L22. When focusing from an object at infinity to a closer object, the focusing lens group on the object side moves towards the image side, and the focusing lens group on the image side moves towards the object side.

[0335] Regarding the fixed-focus optical system of Example 18, the basic lens data is shown in Table 48, the specifications and variable surface spacing are shown in Table 49, the aspherical coefficients are shown in Table 50, and the various aberrations are illustrated in Table 50. Figure 37 middle.

[0336]

[0337]

[0338]

[0339] [Example 19]

[0340] The structure and cross-sectional view of the fixed-focus optical system of Example 19 are shown in the figure. Figure 38 The fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of 10 lenses (L11-L20) from the object side to the image side. The rear group (GR) consists of 8 lenses (L21-L28) from the object side to the image side. The fixed-focus optical system includes two focusing lens groups. The focusing lens group on the object side consists of lenses L21-L22, and the focusing lens group on the image side consists of lenses L23-L24. When focusing from an object at infinity to a closer object, the focusing lens groups on the object side and the image side change their spacing and move towards the object side.

[0341] Regarding the fixed-focus optical system of Example 19, the basic lens data is shown in Table 51, the specifications and variable surface spacing are shown in Table 52, the aspherical coefficients are shown in Table 53, and the various aberrations are illustrated in Table 54. Figure 39 middle.

[0342]

[0343]

[0344]

[0345] [Example 20]

[0346] The structure and cross-sectional view of the fixed-focus optical system of Example 20 are shown in the figure. Figure 40 The fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) comprises eight lenses (L11-L18) from the object side to the image side. The rear group (GR) comprises eight lenses (L21-L28) from the object side to the image side. The fixed-focus optical system includes two focusing lens groups. The focusing lens group on the object side consists of lenses L21-L22, and the focusing lens group on the image side consists of lenses L23-L24. When focusing from an object at infinity to a closer object, the focusing lens groups on the object side and the image side change their spacing and move towards the object side.

[0347] Regarding the fixed-focus optical system of Example 20, the basic lens data are shown in Table 54, the specifications and variable surface spacing are shown in Table 55, the aspherical coefficients are shown in Table 56, and the various aberrations are illustrated in Table 57. Figure 41 middle.

[0348]

[0349]

[0350]

[0351] [Example 21]

[0352] The structure and cross-sectional view of the fixed-focus optical system of Example 21 are shown in the figure. Figure 42The fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) comprises six lenses, L11 through L16, arranged sequentially from the object side to the image side. The rear group (GR) comprises six lenses, L21 through L26, arranged sequentially from the object side to the image side. The fixed-focus optical system includes two focusing lens groups. The focusing lens group on the object side consists of lenses L15 and L16, and the focusing lens group on the image side consists of lens L21. When focusing from an object at infinity to a closer object, the focusing lens group on the object side moves towards the image side, and the focusing lens group on the image side moves towards the object side.

[0353] Regarding the fixed-focus optical system of Example 21, the basic lens data is shown in Table 57, the specifications and variable surface spacing are shown in Table 58, and the various aberrations are illustrated in Table 59. Figure 43 middle.

[0354]

[0355]

[0356] [Example 22]

[0357] The structure and cross-sectional view of the fixed-focus optical system of Example 22 are shown in the figure. Figure 44 The fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with negative optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of five lenses (L11-L15) from the object side to the image side. The rear group (GR) consists of nine lenses (L21-L29) from the object side to the image side. The fixed-focus optical system includes two focusing lens groups. The focusing lens group on the object side consists of lens L22, and the focusing lens group on the image side consists of lens L26. When focusing from an object at infinity to a closer object, the focusing lens group on the object side moves towards the image side, and the focusing lens group on the image side moves towards the object side.

[0358] Regarding the fixed-focus optical system of Example 22, the basic lens data are shown in Table 59, the specifications and variable surface spacing are shown in Table 60, the aspherical coefficients are shown in Table 61, and the various aberrations are illustrated in Table 61. Figure 45 middle.

[0359]

[0360]

[0361]

[0362] [Example 23]

[0363] The structure and cross-sectional view of the fixed-focus optical system of Example 23 are shown in the figure. Figure 46 The fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with negative optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of five lenses (L11-L15) from the object side to the image side. The rear group (GR) consists of nine lenses (L21-L29) from the object side to the image side. The fixed-focus optical system includes two focusing lens groups. The focusing lens group on the object side consists of lens L22, and the focusing lens group on the image side consists of lens L26. When focusing from an object at infinity to a closer object, the focusing lens group on the object side moves towards the image side, and the focusing lens group on the image side moves towards the object side.

[0364] Regarding the fixed-focus optical system of Example 23, the basic lens data are shown in Table 62, the specifications and variable surface spacing are shown in Table 63, the aspherical coefficients are shown in Table 64, and the various aberrations are illustrated in Table 65. Figure 47 middle.

[0365]

[0366]

[0367]

[0368] [Example 24]

[0369] The structure and cross-sectional view of the fixed-focus optical system of Example 24 are shown in the figure. Figure 48 The fixed-focus optical system consists of a front group (GF) with negative optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of four lenses (L11-L14) from the object side to the image side. The rear group (GR) consists of eleven lenses (L21-L31) from the object side to the image side. The fixed-focus optical system includes two focusing lens groups. The focusing lens group on the object side consists of lens L14, and the focusing lens group on the image side consists of lens L29. When focusing from an object at infinity to a closer object, the focusing lens group on the object side moves towards the image side, and the focusing lens group on the image side moves towards the object side.

[0370] Regarding the fixed-focus optical system of Example 24, the basic lens data is shown in Table 65, the specifications and variable surface spacing are shown in Table 66, the aspherical coefficients are shown in Tables 67A and 67B, and the various aberrations are illustrated in Table 67A. Figure 49 middle.

[0371]

[0372]

[0373]

[0374]

[0375] [Example 25]

[0376] The structure and cross-sectional view of the fixed-focus optical system of Example 25 are shown in the figure. Figure 50 The fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) consists of nine lenses (L11-L19) from the object side to the image side. The rear group (GR) consists of six lenses (L21-L26) from the object side to the image side. The fixed-focus optical system includes two focusing lens groups. The focusing lens group on the object side consists of lenses L16-L17, and the focusing lens group on the image side consists of lenses L21-L24. When focusing from an object at infinity to a closer object, the focusing lens groups on the object side and the image side change their spacing and move towards the object side.

[0377] Regarding the fixed-focus optical system of Example 25, the basic lens data are shown in Table 68, the specifications and variable surface spacing are shown in Table 69, the aspherical coefficients are shown in Table 70, and the various aberrations are illustrated in Table 68. Figure 51 middle.

[0378]

[0379]

[0380]

[0381] [Example 26]

[0382] The structure and cross-sectional view of the fixed-focus optical system of Example 26 are shown in the figure. Figure 52 The fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) comprises eight lenses (L11-L18) from the object side to the image side. The rear group (GR) comprises six lenses (L21-L26) from the object side to the image side. The fixed-focus optical system includes two focusing lens groups. The focusing lens group on the object side consists of lens L16, and the focusing lens group on the image side consists of lenses L21-L24. When focusing from an object at infinity to a closer object, the focusing lens groups on the object side and the image side change their spacing and move towards the object side.

[0383] Regarding the fixed-focus optical system of Example 26, the basic lens data is shown in Table 71, the specifications and variable surface spacing are shown in Table 72, the aspherical coefficients are shown in Table 73, and the various aberrations are illustrated in Table 74. Figure 53 middle.

[0384]

[0385]

[0386]

[0387] [Example 27]

[0388] The structure and cross-sectional view of the fixed-focus optical system of Example 27 are shown in [the figure]. Figure 54 The fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) comprises six lenses (L11-L16) from the object side to the image side. The rear group (GR) comprises ten lenses (L21-L30) from the object side to the image side. The fixed-focus optical system includes two focusing lens groups. The focusing lens group on the object side includes lens L16, and the focusing lens group on the image side consists of lenses L26-L27. When focusing from an object at infinity to a closer object, the focusing lens group on the object side moves towards the image side, and the focusing lens group on the image side moves towards the object side.

[0389] Regarding the fixed-focus optical system of Example 27, the basic lens data is shown in Table 74, the specifications and variable surface spacing are shown in Table 75, the aspherical coefficients are shown in Table 76, and the various aberrations are illustrated in Table 77. Figure 55 middle.

[0390]

[0391]

[0392]

[0393] [Example 28]

[0394] The structure and cross-sectional view of the fixed-focus optical system of Example 28 are shown in the figure. Figure 56A fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) comprises six lenses (L11-L16) from the object side to the image side. The rear group (GR) comprises five lenses (L21-L25) from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group, consisting of the aperture stop (St) and the rear group (GR), moves towards the object side when focusing from an infinity object to a closer object.

[0395] Regarding the fixed-focus optical system of Example 28, the basic lens data is shown in Table 77, the specifications and variable surface spacing are shown in Table 78, the aspherical coefficients are shown in Table 79, and the various aberrations are illustrated in Table 78. Figure 57 middle.

[0396]

[0397]

[0398]

[0399] [Example 29]

[0400] The structure and cross-sectional view of the fixed-focus optical system of Example 29 are shown in the figure. Figure 58 A fixed-focus optical system consists of, from the object side to the image side, a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power. The front group (GF) consists of three lenses (L11-L13) from the object side to the image side. The rear group (GR) consists of eight lenses (L21-L28) from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group, composed of lenses L26-L28, moves towards the image side when focusing from an object at infinity to a closer object.

[0401] Regarding the fixed-focus optical system of Example 29, basic lens data are shown in Table 80, specifications and variable surface spacing are shown in Table 81, and various aberrations are illustrated in Table 82. Figure 59 .

[0402]

[0403]

[0404] [Example 30]

[0405] The structure and cross-sectional view of the fixed-focus optical system of Example 30 are shown in the figure. Figure 60A fixed-focus optical system consists of a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power, arranged sequentially from the object side to the image side. The front group (GF) comprises six lenses (L11-L16) from the object side to the image side. The rear group (GR) comprises five lenses (L21-L25) from the object side to the image side. The fixed-focus optical system includes only one focusing lens group. This focusing lens group, consisting of the aperture stop (St) and the rear group (GR), moves towards the object side when focusing from an infinity object to a closer object.

[0406] Regarding the fixed-focus optical system of Example 30, basic lens data are shown in Table 82, specifications and variable surface spacing are shown in Table 83, and various aberrations are illustrated in Table 84. Figure 61 middle.

[0407]

[0408]

[0409] [Example 31]

[0410] The structure and cross-sectional view of the fixed-focus optical system of Example 31 are shown in the figure. Figure 62 The fixed-focus optical system consists of, from the object side to the image side, a front group (GF) with positive optical power, an aperture stop (St), and a rear group (GR) with positive optical power. The front group (GF) consists of three lenses (L11 to L13) from the object side to the image side. The rear group (GR) consists of five lenses (L21 to L25) from the object side to the image side. The focusing lens group is part of the fixed-focus optical system and moves towards the object side when focusing from an object at infinity to a closer object.

[0411] Regarding the fixed-focus optical system of Example 31, the basic lens data is shown in Table 84, the specifications and variable surface spacing are shown in Table 85, and the various aberrations are illustrated in Table 86. Figure 63 middle.

[0412]

[0413]

[0414] [Example 32]

[0415] The structure and cross-sectional view of the fixed-focus optical system of Example 32 are shown in the figure. Figure 64 A fixed-focus optical system consists, from the object side to the image side, a front group GF with positive optical power, an aperture stop St, and a rear group GR with positive optical power. The front group GF consists of two lenses, L11 and L12, from the object side to the image side. The rear group GR consists of three lenses, L21 and L23, from the object side to the image side.

[0416] Regarding the fixed-focus optical system of Example 32, basic lens data are shown in Table 86, specifications are shown in Table 87, and various aberrations are illustrated in Table 88. Figure 65 .

[0417]

[0418]

[0419] [Example 33]

[0420] The structure and cross-sectional view of the fixed-focus optical system of Example 33 are shown in the figure. Figure 66 A fixed-focus optical system consists, from the object side to the image side, a front group GF with positive optical power, an aperture stop St, and a rear group GR with positive optical power. The front group GF consists of two lenses, L11 and L12, from the object side to the image side. The rear group GR consists of four lenses, L21 to L24, from the object side to the image side.

[0421] Regarding the fixed-focus optical system of Example 33, basic lens data are shown in Table 88, specifications are shown in Table 89, and various aberrations are illustrated in Table 88. Figure 67 middle.

[0422]

[0423]

[0424] [Example 34]

[0425] The structure and cross-sectional view of the fixed-focus optical system of Example 34 are shown in the figure. Figure 68 A fixed-focus optical system consists, from the object side to the image side, a front group GF with positive optical power, an aperture stop St, and a rear group GR with positive optical power. The front group GF consists of three lenses, L11 to L13, from the object side to the image side. The rear group GR consists of three lenses, L21 to L23, from the object side to the image side.

[0426] Regarding the fixed-focus optical system of Example 34, basic lens data are shown in Table 90, specifications are shown in Table 91, and various aberrations are illustrated in Table 92. Figure 69 .

[0427]

[0428]

[0429] Table 92 shows the corresponding values ​​of conditional expressions (1) to (3) for “N231. Glass”, “N216. Glass” and “N200. Glass” used in the above embodiments. Tables 93 to 99 show the corresponding values ​​of conditional expressions (4) to (20) for the fixed-focus optical systems of embodiments 1 to 34 above. The corresponding values ​​shown in Tables 92 to 99 can also be used as upper or lower limits of the conditional expressions to set the preferred range of the conditional expressions.

[0430]

[0431]

[0432]

[0433]

[0434]

[0435]

[0436]

[0437]

[0438] Next, the imaging device according to the embodiments of the present invention will be described. Figure 70 and Figure 71 The image shows an external view of a camera 30, which is an imaging device according to one embodiment of the present invention. Figure 70 This is a stereoscopic view of camera 30 viewed from the front side. Figure 71 This is a perspective view of the camera 30 as seen from the rear side. The camera 30 is a so-called mirrorless digital camera, which allows for the detachable mounting of an interchangeable lens 20. The interchangeable lens 20 is configured to include a fixed-focus optical system 1 according to an embodiment of the present invention, housed within a lens barrel. In this example, the fixed-focus optical system 1 functions as an imaging lens.

[0439] The camera 30 includes a camera body 31. A shutter button 32 and a power button 33 are provided on the upper surface of the camera body 31. Furthermore, an operation unit 34, an operation unit 35, and a display unit 36 ​​are provided on the back of the camera body 31. The display unit 36 ​​can display the captured image and the image existing in the field of view before shooting.

[0440] A photographic opening for light from the photographed object is provided at the center of the front surface of the camera body 31. A bayonet 37 is provided at a position corresponding to the photographic opening, through which the interchangeable lens 20 is mounted on the camera body 31.

[0441] An imaging element 38 is provided within the camera body 31. The imaging element 38 outputs an imaging signal corresponding to the image of the subject formed by the interchangeable lens 20. The imaging element 38 can be, for example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). A signal processing circuit (not shown) and a recording medium (not shown) are also provided within the camera body 31. The signal processing circuit processes the imaging signal output from the imaging element 38 to generate an image. The recording medium is used to record the generated image. In the camera 30, still images or videos can be captured by pressing the shutter button 32, and the image data obtained through this capture is recorded in the aforementioned recording medium.

[0442] The above description, through examples and embodiments, illustrates the technology of the present invention. However, the technology of the present invention is not limited to the above examples and embodiments, and various modifications are possible. For example, the radius of curvature, interplanar spacing, refractive index, Abbe number, and aspherical coefficient of each lens are not limited to the values ​​shown in the above embodiments, and other values ​​can be used.

[0443] Furthermore, the imaging device involved in the embodiments of the present invention is not limited to the above examples. For example, it can be configured as a camera other than a mirrorless type, a camera in which the imaging lens and the camera body are integrated, a film camera, a video camera, a surveillance camera, a broadcast camera, a movie camera, a FA (Factory Automation) camera, and a MV (Machine Vision) camera, etc.

[0444] The following notes further disclose the above-described implementation methods and embodiments.

[0445] [Postscript 1]

[0446] A fixed-focus optical system, comprising, from the object side to the image side, a front group, an aperture, and a rear group, wherein...

[0447] The fixed-focus optical system includes at least one specific lens, wherein the refractive index of the lenses included in the fixed-focus optical system relative to the d-line is set to Nd.

[0448] When the Abbe number of the d-line reference of the lenses included in the fixed-focus optical system is set to νd,

[0449] The following conditions (1) and (2) are satisfied:

[0450] 2.435<Nd+0.01425×νd<2.75 (1)

[0451] 15<νd<39 (2)。

[0452] [Postscript 2]

[0453] According to the fixed-focus optical system described in Appendix 1, wherein...

[0454] When the partial dispersion ratio between the g-line and F-line of the lens included in the fixed-focus optical system is set to θgF,

[0455] The specific lens satisfies the following conditional expression (3):

[0456] 0.65<θgF+0.00316×νd<0.85 (3).

[0457] [Postscript 3]

[0458] According to the fixed-focus optical system described in Appendix 1 or 2, wherein,

[0459] When the focal length of the front group is set to fF while focusing on an object at infinity,

[0460] When the focal length of the rear group is set to fR while focusing on an object at infinity,

[0461] The fixed-focus optical system satisfies the following condition (4):

[0462] -5<fR / fF<10 (4)。

[0463] [Postscript 4]

[0464] According to any one of Appendices 1 to 3, in the fixed-focus optical system, wherein...

[0465] It is equipped with at least one focusing lens group that moves along the optical axis during focusing.

[0466] [Postscript 5]

[0467] According to the fixed-focus optical system described in Appendix 4, wherein...

[0468] The focal length of the focusing lens group with the strongest optical power among the focusing lens groups included in the fixed-focus optical system is set to ffocmax.

[0469] When the focal length of the fixed-focus optical system is set to f while focusing on an object at infinity,

[0470] The fixed-focus optical system satisfies the following condition (5):

[0471] 0.2<|ffocmax / f|<3.5 (5).

[0472] [Postscript 6]

[0473] According to the fixed-focus optical system described in Appendix 4 or 5, wherein,

[0474] The fixed-focus optical system includes two focusing lens groups.

[0475] When the focal length of the focusing lens group on the object side of the two focusing lens groups is set to ff1,

[0476] When the focal length of the image-side focusing lens group in the two focusing lens groups is set to ff2,

[0477] The fixed-focus optical system satisfies the following condition (6):

[0478] 0.1<|ff1 / ff2|<10 (6).

[0479] [Postscript 7]

[0480] According to any one of Appendices 4 to 6, in the fixed-focus optical system, wherein...

[0481] The combined focal length of all lenses in the fixed-focus optical system that are more object-side than the most object-side focusing lens group in the focusing lens group is set to ffocF.

[0482] When the focal length of the fixed-focus optical system is set to f while focusing on an object at infinity,

[0483] The fixed-focus optical system satisfies the following condition (7):

[0484] -2<f / ffocF<6 (7)。

[0485] [Postscript 8]

[0486] According to any one of Appendices 4 to 7, in the fixed-focus optical system, wherein...

[0487] The combined focal length of all lenses in the fixed-focus optical system that are more image-side than the most image-side focusing lens group is set to ffocR.

[0488] When the focal length of the fixed-focus optical system is set to f while focusing on an object at infinity,

[0489] The fixed-focus optical system satisfies the following condition (8):

[0490] -6<f / ffocR<2 (8).

[0491] [Postscript 9]

[0492] According to any one of Annexes 4 to 8, the fixed-focus optical system wherein...

[0493] The rear group is equipped with two focusing lens groups that move along different trajectories during focusing.

[0494] [Postscript 10]

[0495] According to any one of Appendices 4 to 9, in the fixed-focus optical system, wherein...

[0496] One focusing lens group is configured in each of the front and rear groups.

[0497] The front focusing lens group and the rear focusing lens group move along different trajectories during focusing.

[0498] The combined focal length of all lenses in the fixed-focus optical system that are more object-side than the most object-side focusing lens group in the focusing lens group is set to ffocF.

[0499] When the combined focal length from the lens adjacent to the image side of the focusing lens group in the preceding group to the lens adjacent to the object side of the focusing lens group in the following group is set to fM,

[0500] The fixed-focus optical system satisfies the following condition (9):

[0501] 0.1<|ffocF / fM|<2 (9).

[0502] [Postscript 11]

[0503] According to any one of Annexes 4 to 10, in the fixed-focus optical system, wherein,

[0504] At least one of the focusing lens groups includes at least one of the specific lenses.

[0505] [Postscript 12]

[0506] According to any one of Appendices 1 to 11, in the fixed-focus optical system, wherein,

[0507] The rear group includes at least one of the specific lenses.

[0508] [Postscript 13]

[0509] According to any one of Appendices 1 to 12, in the fixed-focus optical system, wherein,

[0510] The front group includes at least one of the specific lenses.

[0511] [Postscript 14]

[0512] According to any one of Appendices 1 to 13, in the fixed-focus optical system, wherein...

[0513] The front group and the rear group each include at least one of the specific lenses.

[0514] [Postscript 15]

[0515] The fixed-focus optical system according to any one of Appendices 1 to 14 includes at least one joint lens.

[0516] At least one of the said joint lenses includes at least one of the specific lenses.

[0517] [Postscript 16]

[0518] According to any one of Appendices 1 to 15, in the fixed-focus optical system, wherein...

[0519] The rear group includes an anti-vibration group that moves in a direction intersecting the optical axis when correcting image jitter.

[0520] When the focal length of the vibration damping group is set to fIS,

[0521] When the focal length of the fixed-focus optical system is set to f while focusing on an object at infinity,

[0522] The fixed-focus optical system satisfies the following condition (10):

[0523] 0.05<|fIS / f|<2 (10).

[0524] [Note 17] In the fixed-focus optical system according to Note 16, wherein,

[0525] The vibration damping assembly includes at least one of the specific lenses.

[0526] [Postscript 18]

[0527] According to any one of Appendices 1 to 17, in the fixed-focus optical system, wherein...

[0528] The maximum half angle of view when focusing on an object at infinity is less than 7 degrees.

[0529] The maximum value of the air gap on the optical axis within the front group when focusing on an object at infinity is set to Amax.

[0530] When the distance on the optical axis from the lens surface closest to the object to the lens surface closest to the image in the front group is set to TLf, in the case where the image is focused on an object at infinity,

[0531] The fixed-focus optical system satisfies the following condition (11):

[0532] 0.2<Amax / TLf<0.8 (11).

[0533] [Postscript 19]

[0534] According to any one of Appendices 1 to 18, in the fixed-focus optical system, wherein...

[0535] When focusing on the object at the longest possible distance, the angle relative to the optical axis when the principal ray of maximum angle of view is incident on the image plane is set as θc.

[0536] If the unit of θc is set to degrees,

[0537] The fixed-focus optical system satisfies the following condition (12):

[0538] 0 < |θc| < 30 (12).

[0539] [Postscript 20]

[0540] A camera device comprising a fixed-focus optical system as described in any one of Appendices 1 to 19.

Claims

1. A fixed-focus optical system, comprising, from the object side to the image side, a front group, an aperture, and a rear group, wherein, The fixed-focus optical system includes at least one specific lens, wherein the refractive index of the lenses included in the fixed-focus optical system relative to the d-line is set to Nd. When the Abbe number of the d-line reference of the lenses included in the fixed-focus optical system is set to νd, The following conditions (1) and (2) are satisfied: 2.435<Nd+0.01425×νd<2.75 (1) 15<νd<39 (2)。 2. The fixed-focus optical system according to claim 1, wherein, When the partial dispersion ratio between the g-line and F-line of the lens included in the fixed-focus optical system is set to θgF, The specific lens satisfies the following conditional expression (3): 0.65<θgF+0.00316×νd<0.85 (3).

3. The fixed-focus optical system according to claim 1 or 2, wherein, When the focal length of the front group is set to fF while focusing on an object at infinity, When the focal length of the rear group is set to fR while focusing on an object at infinity, The fixed-focus optical system satisfies the following condition (4): -5<fR / fF<10 (4)。 4. The fixed-focus optical system according to claim 1 or 2, wherein, It is equipped with at least one focusing lens group that moves along the optical axis during focusing.

5. The fixed-focus optical system according to claim 4, wherein, The focal length of the focusing lens group with the strongest optical power among the focusing lens groups included in the fixed-focus optical system is set to ffocmax. When the focal length of the fixed-focus optical system is set to f while focusing on an object at infinity, The fixed-focus optical system satisfies the following condition (5): 0.2<|ffocmax / f|<3.5 (5).

6. The fixed-focus optical system according to claim 4, wherein, The fixed-focus optical system includes two focusing lens groups. When the focal length of the focusing lens group on the object side of the two focusing lens groups is set to ff1, When the focal length of the image-side focusing lens group in the two focusing lens groups is set to ff2, The fixed-focus optical system satisfies the following condition (6): 0.1<|ff1 / ff2|<10 (6).

7. The fixed-focus optical system according to claim 4, wherein, The combined focal length of all lenses in the fixed-focus optical system that are more object-side than the most object-side focusing lens group in the focusing lens group is set to ffocF. When the focal length of the fixed-focus optical system is set to f while focusing on an object at infinity, The fixed-focus optical system satisfies the following condition (7): -2<f / ffocF<6 (7)。 8. The fixed-focus optical system according to claim 4, wherein, The combined focal length of all lenses in the fixed-focus optical system that are more image-side than the most image-side focusing lens group is set to ffocR. When the focal length of the fixed-focus optical system is set to f while focusing on an object at infinity, The fixed-focus optical system satisfies the following condition (8): -6<f / ffocR<2 (8).

9. The fixed-focus optical system according to claim 4, wherein, The rear group is equipped with two focusing lens groups that move along different trajectories during focusing.

10. The fixed-focus optical system according to claim 4, wherein, One focusing lens group is configured in each of the front and rear groups. The front focusing lens group and the rear focusing lens group move along different trajectories during focusing. The combined focal length of all lenses in the fixed-focus optical system that are more object-side than the most object-side focusing lens group in the focusing lens group is set to ffocF. When the combined focal length from the lens adjacent to the image side of the focusing lens group in the preceding group to the lens adjacent to the object side of the focusing lens group in the following group is set to fM, The fixed-focus optical system satisfies the following condition (9): 0.1<|ffocF / fM|<2 (9).

11. The fixed-focus optical system according to claim 4, wherein, At least one of the focusing lens groups includes at least one of the specific lenses.

12. The fixed-focus optical system according to claim 1 or 2, wherein, The rear group includes at least one of the specific lenses.

13. The fixed-focus optical system according to claim 1 or 2, wherein, The front group includes at least one of the specific lenses.

14. The fixed-focus optical system according to claim 1 or 2, wherein, The front group and the rear group each include at least one of the specific lenses.

15. The fixed-focus optical system according to claim 1 or 2, comprising at least one joint lens. At least one of the said joint lenses includes at least one of the specific lenses.

16. The fixed-focus optical system according to claim 1 or 2, wherein, The rear group includes an anti-vibration group that moves in a direction intersecting the optical axis when correcting image jitter. When the focal length of the vibration damping group is set to fIS, When the focal length of the fixed-focus optical system is set to f while focusing on an object at infinity, The fixed-focus optical system satisfies the following condition (10): 0.05<|fIS / f|<2 (10).

17. The fixed-focus optical system according to claim 16, wherein, The vibration damping assembly includes at least one of the specific lenses.

18. The fixed-focus optical system according to claim 1 or 2, wherein, The maximum half-angle of view when focusing on an object at infinity is less than 7 degrees. The maximum value of the air gap on the optical axis within the front group when focusing on an object at infinity is set to Amax. When focusing on an object at infinity, the distance along the optical axis from the lens surface closest to the object in the front group to the lens surface closest to the image in the front group is set to TLf. The fixed-focus optical system satisfies the following condition (11): 0.2<Amax / TLf<0.8 (11).

19. The fixed-focus optical system according to claim 1 or 2, wherein, When focusing on the object at the longest possible distance, the angle relative to the optical axis when the principal ray of maximum angle of view is incident on the image plane is set as θc. If the unit of θc is set to degrees, The fixed-focus optical system satisfies the following condition (12): 0 < |θc| < 30 (12).

20. A camera device comprising the fixed-focus optical system according to any one of claims 1 to 19.

Images