Zoom lens and imaging device

Abstract

To provide a zoom lens which is advantageous in terms of a high zoom ratio and high optical performance over a wavelength range from visible light to SWIR light, for example.SOLUTION: A zoom lens disclosed herein comprises a first lens group with positive refractive power configured to be stationary for zooming, multiple movable lens groups including at least one lens group with negative refractive power, and a rear lens group with positive refractive power configured to be stationary for zooming, arranged in order from the object side to the image side, and is configured such that a distance between each pair of adjacent lens groups changes for zooming. Focal lengths of the zoom lens at the wide-angle end and telephoto end while focused at infinity, a focal length of the first lens group, and an open F-number of the zoom lens at the wide-angle end are appropriately set. The rear lens group includes multiple negative lenses that satisfy a given relationship regarding a refractive index for the d-ray and a first partial dispersion ratio defined by refractive indexes for the C-ray, F-ray, and 1970-nm light.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a zoom lens and an imaging device. [Background technology]

[0002] Imaging devices used for long-distance monitoring in ports and other areas require zoom lenses with high zoom ratios and high optical performance. Furthermore, for imaging at night or in dense fog, high optical performance is required in the wavelength range from visible to near-infrared.

[0003] As such a high zoom ratio zoom lens, a positive lead type zoom lens has been proposed. Patent Document 1 discloses a zoom lens consisting of a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a fourth lens group with positive refractive power, arranged in order from the object side to the image side, with the second lens group and the third lens moving along the optical axis, and having a zoom ratio of about 20. The refractive index at a near-infrared wavelength of 1700 nm is defined and aberration correction in the wavelength range from visible to near-infrared is disclosed.

[0004] Furthermore, Patent Document 2 discloses a zoom lens consisting of a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a fourth lens group with positive refractive power, arranged in order from the object side to the image side, with the second and third lens groups moving along the optical axis and having a zoom ratio of approximately 60. It specifies the refractive index at a near-infrared wavelength of 1970 nm and discloses aberration correction in the wavelength range from visible to near-infrared. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2016-95448 [Patent Document 2] Japanese Patent Publication No. 2021-76780 [Overview of the project] [Problems that the invention aims to solve]

[0006] In wide-angle, high-zoom-ratio surveillance zoom lenses, correcting axial chromatic aberration at the wide-angle end is difficult.

[0007] The zoom lenses described in Patent Documents 1 and 2 do not adequately correct chromatic aberration from the visible light wavelength range to the short-wavelength infrared (SWIR) light wavelength range (wavelength: 0.9 to 1.7 μm). The present invention aims to provide a zoom lens that is advantageous in terms of, for example, a high zoom ratio and high optical performance in the wavelength range from visible light to SWIR light. [Means for solving the problem]

[0008] In one aspect of the present invention, the zoom lens comprises, in order from the object side to the image side, a first lens group with positive refractive power that does not move for zooming, a plurality of moving lens groups including at least one lens group with negative refractive power, and a rear lens group with positive refractive power that does not move for zooming. Consists of In a zoom lens, where the spacing between adjacent lens groups changes for zooming, and the focal length of the zoom lens at infinity focus and the wide-angle end is fw, the focal length of the zoom lens at infinity focus and the telephoto end is ft, the focal length of the first lens group is f1, and the maximum aperture F-number of the zoom lens at the wide-angle end is Fnw, 3.5 ≤ ft / f1 ≤ 6.0 4.7 ≤ fw / Fnw ≤ 12.0 The following conditions are met: When the refractive indices of the material for the C line, F line, and 1970 nm wavelengths are NC, NF, and N1970, respectively, the first partial dispersion ratio θs is: θs = (NC - N1970) / (NF - NC) Defined by, The aforementioned rear lens group has a refractive index of Ndn with respect to the d line and a first partial dispersion ratio of θsn. 1.55 ≤ Ndn ≤ 1.75 2.10 ≤ θsn ≤ 2.60 including a plurality of negative lenses formed of a material satisfying a conditional expression fruit, When the Abbe number of the material that is included in the rear lens group and forms a positive lens positioned next to any of the plurality of negative lenses is νp, 55≦νp≦120 Includes multiple positive lenses formed from materials that satisfy the following condition: characterized by this

Advantages of the Invention

[0009] According to the present invention, for example, a zoom lens advantageous in terms of a high zoom ratio and high optical performance in a wavelength range from visible light to SWIR light can be provided.

Brief Description of the Drawings

[0010] [Figure 1] It is a lens cross-sectional view when focused at infinity at the wide-angle end of Numerical Example 1. [Figure 2] It is an aberration diagram when focused at infinity at the wide-angle end (a), f = 93.4 mm (b), and telephoto end (c) of Numerical Example 1. [Figure 3] It is a lens cross-sectional view when focused at infinity at the wide-angle end of Numerical Example 2. [Figure 4] It is an aberration diagram when focused at infinity at the wide-angle end (a), f = 215.8 mm (b), and telephoto end (c) of Numerical Example 2. [Figure 5] It is a lens cross-sectional view when focused at infinity at the wide-angle end of Numerical Example 3. [Figure 6] It is an aberration diagram when focused at infinity at the wide-angle end (a), f = 131.0 mm (b), and telephoto end (c) of Numerical Example 3. [Figure 7] It is a lens cross-sectional view when focused at infinity at the wide-angle end of Numerical Example 4. [Figure 8] It is an aberration diagram when focused at infinity at the wide-angle end (a), f = 120 mm (b), and telephoto end (c) of Numerical Example 4. [Figure 9] It is a lens cross-sectional view when focused at infinity at the wide-angle end of Numerical Example 5. [Figure 10]This is an aberration diagram for Numerical Example 5, showing the wide-angle end (a), f=155mm (b), and the telephoto end (c) when focused at infinity. [Figure 11] This is a conceptual diagram of the distribution of existing optical materials. [Figure 12] This is a schematic diagram of the main components of the imaging device of the present invention. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Traditionally, imaging devices such as surveillance video cameras used for long-distance monitoring in ports and other locations have required zoom lenses with high zoom ratios and high optical performance. In particular, imaging devices used in advanced surveillance systems have high light sensitivity in the visible to near-infrared wavelength range for nighttime and foggy conditions. Therefore, zoom lenses that meet these requirements must also have good optical performance correction in the visible to near-infrared range.

[0012] In zoom lenses for surveillance cameras that utilize both visible and near-infrared light, near-infrared light, specifically the NIR (Near InfraRed) to SWIR region (around 1000-2000 nm), is often used for nighttime imaging. Ideally, to obtain good imaging performance in this near-infrared region, aberrations from visible light to near-infrared light should be corrected to zero. However, in actual zoom lenses, axial chromatic aberration and lateral chromatic aberration remain in the infrared region. Of these, residual axial chromatic aberration in infrared light significantly affects image quality as it causes focus shifts during infrared imaging. Therefore, various methods have been developed to effectively correct near-infrared aberrations in zoom lenses, as well as to provide further adjustments for near-infrared imaging.

[0013] Conventionally, high-magnification zoom lenses suitable for surveillance cameras have incorporated a focusing mechanism in the first lens group to suppress the amount of extension even at the telephoto end where axial chromatic aberration tends to increase. However, at the wide-angle end, the focusing sensitivity of the first lens group tends to decrease as the magnification of the zoom lens increases, leading to an increased amount of drive required to correct focus errors caused by near-infrared axial chromatic aberration, resulting in larger lenses. Similarly, the flange back adjustment mechanism in the rear lens group of the zoom lens also requires increased adjustment, which is detrimental to miniaturizing and simplifying the system. Even at the wide-angle end, where axial chromatic aberration is generally small, axial chromatic aberration in the near-infrared region can occur to an extent exceeding the depth of field. Therefore, suppressing near-infrared axial chromatic aberration is essential to achieve well-focused shooting with small and lightweight lenses. For these reasons, it is necessary to effectively correct near-infrared axial chromatic aberration at the wide-angle end in zoom lenses used for surveillance applications, which handle everything from wide-area search to subject identification.

[0014] The present invention aims to provide a zoom lens that has a high zoom ratio and good imaging performance for light across a wide wavelength range from the visible to the near-infrared region.

[0015] First, the features of the zoom lens of the present invention will be explained according to each conditional formula. The present invention defines the power arrangement of the zoom lens and the characteristics of the optical materials used in each lens group in order to achieve a zoom lens with a high zoom ratio and high optical performance in the visible to near-infrared wavelength range across the entire zoom range. Specifically, it makes it possible to provide a zoom lens with a zoom ratio of about 20 to 150, in which axial chromatic aberration in the visible to near-infrared wavelength range is well corrected, especially at the wide-angle end.

[0016] The zoom lens of the present invention comprises, in order from the object side to the image side, a first lens group with positive refractive power that does not move for zooming but whose whole or a part moves along the optical axis for focusing, a plurality of moving lens groups including at least one lens group with negative refractive power, and a rear lens group with positive refractive power that does not move for zooming, wherein the spacing between adjacent lens groups changes for zooming, and when the focal length of the zoom lens at infinity focus and the wide-angle end is fw, the focal length of the zoom lens at infinity focus and the telephoto end is ft, the focal length of the first lens group is f1, and the maximum aperture F number at the wide-angle end of the zoom lens is Fnw, 3.5 ≤ ft / f1 ≤ 6.0 ···(1) 4.7 ≤ fw / Fnw ≤ 12.0 ···(2) The following conditions are met: When the refractive indices of the material for the C line, F line, and 1970 nm wavelengths are NC, NF, and N1970, respectively, the first partial dispersion ratio θs is: θs=(NC-N1970) / (NF-NC) ···(a) Defined by, The aforementioned rear lens group, when the refractive index with respect to the d line is Ndn and the first partial dispersion ratio is θsn, 1.55 ≤ Ndn ≤ 1.75 ···(3) 2.10 ≤ θsn ≤ 2.60 ···(4) The present invention is characterized by including multiple negative lenses formed from materials that satisfy the following condition:

[0017] The zoom lens of the present invention is a positive lead type zoom lens with a first lens group having positive refractive power, and is configured with a power arrangement suitable for a surveillance zoom lens that satisfies equations (1) and (2) above.

[0018] The first lens group does not move for zooming, but the entire or a part of the first lens group moves in the optical axis direction for focusing. The subsequent lens group has a moving lens group consisting of two or more groups, including at least one lens group with negative refractive power, and a rear lens group with positive refractive power that does not move for zooming. The aperture is located between or within the lens groups following the first lens group. The rear lens group and the lens groups before and after it may have a focal length conversion optical system that changes the focal length of the entire zoom lens by inserting or removing different lens groups into or from the optical path. Furthermore, a back drive mechanism may be provided that can suppress focus shift during zooming to almost zero throughout the entire zoom range by moving the entire or a part of the rear lens group slightly along the optical axis.

[0019] Equations (1) and (2) specify the zoom lens configuration in which the present invention is most effective. Equation (1) specifies the ratio of the focal length of this zoom lens to the focal length of the first lens group at the telephoto end. By satisfying equation (1), a power relationship of the first lens group suitable for the specifications and performance of a surveillance lens can be configured. If the upper limit condition of equation (1) is not met, the focal length of the first lens group becomes relatively shorter, and the aberration amplification rate by the lens group and beyond increases, making it difficult to suppress axial chromatic aberration at the telephoto end. If the lower limit condition of equation (1) is not met, the focal length of the first lens group becomes relatively longer, making it difficult to miniaturize and lighten the lens system and achieve a sufficient telephoto end focal length.

[0020] More preferably, equation (1) should be set as follows: 3.6 ≤ ft / f1 ≤ 5.8 ···(1a)

[0021] More preferably, equation (1a) should be set as follows: 3.7 ≤ ft / f1 ≤ 5.6 ···(1aa)

[0022] More preferably, equation (1aa) should be set as follows: 3.8≦ft / f1≦5.4 (1aaa)

[0023] Equation (2) defines the ratio of the focal length at the wide-angle end to the F-number at the wide-angle end of this zoom lens. By satisfying equation (2), an appropriate power relationship between the focal length at the wide-angle end and a bright F-number suitable for surveillance lenses can be established. If the upper limit condition of equation (2) is not met, the F-number at the wide-angle end becomes relatively bright, resulting in a larger system and an excessively shallow depth of field. If the lower limit condition of equation (2) is not met, the focal length of the rear lens group becomes relatively too long, making it difficult to achieve both a bright F-number and an appropriate focal length at the wide-angle end.

[0024] More preferably, equation (2) should be set as follows: 4.8≦fw / Fnw≦11.5 (2a)

[0025] More preferably, equation (2a) should be set as follows: 4.9≦fw / Fnw≦11.0 (2aa)

[0026] More preferably, equation (2aa) should be set as follows: 5.0≦fw / Fnw≦10.5 (2aaa)

[0027] Equations (3) and (4) specify the rear lens group configuration for achieving aberration correction suitable for infrared surveillance lenses. Equation (3) specifies the condition that the refractive index of the optical materials in the multiple negative lenses included in the rear lens group of this zoom lens is Ndn. Satisfying equation (3) makes it possible to select optical materials that are advantageous for infrared aberration correction and Petzval sum correction among the aberration corrections performed by the negative lenses in the rear lens group. If the upper limit condition of equation (3) is not satisfied, it becomes difficult to select an optical material that is advantageous for infrared aberration correction from existing optical glass materials. If the lower limit condition of equation (3) is not satisfied, it becomes difficult to select an optical material that is advantageous for Petzval sum correction.

[0028] More preferably, equation (3) should be set as follows: 1.57 ≤ Ndn ≤ 1.73 ···(3a)

[0029] More preferably, equation (3a) should be set as follows: 1.59 ≤ Ndn ≤ 1.71 ···(3aa)

[0030] More preferably, equation (3aa) should be set as follows: 1.61≦Ndn≦1.67 (3aaa)

[0031] Equation (4) specifies the conditions for the partial dispersion ratio of the optical material in a plurality of negative lenses included in the rear lens group of this zoom lens. In the present invention, when the refractive indices for the Fraunhofer line wavelengths C line (656.3 nm), F line (486.1 nm), and 1970 nm are NC, NF, and N1970, respectively, θs = (NC - N1970) / (NF - NC) (a) The first partial dispersion ratio θs, defined as θ, is employed. The reason for employing the above wavelengths in this invention is that, among the wavelengths in the visible to SWIR region, refractive index information can be easily obtained from official catalogs of various glass manufacturers (e.g., OHARA). The zoom lens of this invention can exhibit good optical performance not only at the above wavelengths but also at wavelengths in the visible to SWIR region.

[0032] Here, the relationship of chromatic aberration correction in the present invention will be explained. As shown in Figure 11, existing optical materials have a first partial dispersion ratio distributed over a narrow range with respect to the Abbe number, and tend to have a larger first partial dispersion ratio as the Abbe number increases. The axial chromatic aberration coefficient L and lateral chromatic aberration coefficient T of a thin-walled, tightly fitting system composed of two lenses Gp and Gn, having a predetermined refractive power Φ as a whole, with a positive refractive power Φp, a negative refractive power Φn, Abbe numbers νp and νn, incident height h for axial paraxial rays, and incident height H for pupil paraxial rays, are expressed by the following equations (c) and (d). L=h×h×(Φp / νp+Φn / νn) ···(c) T=h×H×(Φp / νp+Φn / νn) ···(d) Here, Φ = Φp + Φn ···(e) Let's assume that.

[0033] Furthermore, axial paraxial rays and pupillary paraxial rays are defined as follows: Axial paraxial rays are paraxial rays incident on the optical system parallel to the optical axis with an incident height of 1, with the focal length at the wide-angle end of the entire optical system normalized to 1. Pupillary paraxial rays are paraxial rays that pass through the intersection of the entrance pupil of the optical system and the optical axis, among the rays incident on the image surface at the maximum image height, with the focal length at the wide-angle end of the entire optical system normalized to 1.

[0034] The refractive forces Φp and Φn of each lens in equations (c) and (d) are normalized so that equation (e) becomes Φ=1. The same consideration can be applied when the lens is composed of three or more elements. In equations (c) and (d), if L=0 and T=0, the image formation positions on the axis and on the image plane of the C-line and F-line coincide. Correcting chromatic aberration for two predetermined wavelengths in this way is generally called two-wavelength achromatic correction (first-order spectral correction). In particular, in high-magnification zoom lenses, the chromatic aberration of each lens group, i.e., L and T, is corrected to be approximately near zero in order to suppress chromatic aberration fluctuations associated with zooming.

[0035] At this time, if we define the amount of deviation in axial chromatic aberration and the amount of deviation in lateral chromatic aberration of the C line with respect to 1970 nm as the second spectral amount of axial chromatic aberration Δs and the second spectral amount of lateral chromatic aberration Δy, respectively, when the light beam is incident with the object distance set to infinity, Δs=-h×h×(θp-θn) / (νp-νn)×f (f) Δy=-h×H×(θp-θn) / (νp-νn)×Y (g) This is expressed as follows: Here, f is the focal length of the entire zoom lens system, and Y is the image height. Correcting chromatic aberration for a specific set of three wavelengths by adding a specific wavelength in this way is generally called three-wavelength aberration correction (second-order spectral correction).

[0036] As the demand for higher specifications in zoom lenses increases, the focal length f in equation (f) increases as a higher zoom ratio is achieved, making it difficult to reduce the second-order spectrum of axial chromatic aberration. In particular, for zoom lenses used in surveillance applications, long focal lengths are highly valued even at the wide-angle end, so it is important to suppress axial chromatic aberration from the wide-angle end. Each embodiment of the present invention provides a technique that achieves high specifications particularly suitable for surveillance zoom lenses, while effectively correcting first-order and second-order axial chromatic aberration from the visible to near-infrared region, which is particularly effective as an offset component from the wide-angle end to the telephoto end.

[0037] (4) By satisfying equation (4), it becomes possible to select an optical material that is advantageous for correcting infrared axial aberration among the aberration corrections performed by the negative lens in the rear lens group. If the upper limit condition of equation (4) is not satisfied, it becomes difficult to select an optical material from existing optical glass materials that is advantageous for both correcting visible aberration and infrared aberration. If the lower limit condition of equation (4) is not satisfied, the correction of infrared axial chromatic aberration performed by the negative lens in the rear lens group is insufficient, which is undesirable.

[0038] More preferably, equation (4) should be set as follows: 2.11 ≤ θsn ≤ 2.55 ···(4a)

[0039] More preferably, equation (4a) should be set as follows: 2.15≦θsn≦2.50 (4aa)

[0040] More preferably, equation (4aa) should be set as follows: 2.20≦θsn≦2.45 (4aaa)

[0041] From the above, by simultaneously employing technologies such as those in equations (1) to (4) in the zoom lens of the present invention, it is possible to achieve both an optimal power arrangement for each group, particularly for high-magnification zoom lenses for surveillance, and suppression of axial chromatic aberration from the visible to infrared range from the wide-angle end.

[0042] In a further embodiment of the zoom lens of the present invention, when the refractive index of the optical material forming the negative lens with respect to the wavelength t line (10¹⁴ nm) is Nt, θt = (NC - Nt) / (NF - NC) ... (b) When the second partial variance ratio θt defined by θtn is denoted by θtn, 0.825 ≤ θtn ≤ 0.900 ···(5) The following condition is met.

[0043] Equation (5), like equation (4), specifies the conditions for the partial dispersion ratio of the optical materials in the multiple negative lenses included in the rear lens group of this zoom lens, but equation (5) specifies the second partial dispersion ratio at the t-line (1014 nm). Equation (4) specifies the first partial dispersion ratio at 1970 nm, thereby specifying chromatic aberration correction in the long wavelength range known as SWIR within the near-infrared wavelength range. However, if it is also necessary to manage aberration correction in the region known as NIR, around 1000-1300 nm, which lies between the visible and SWIR wavelengths, it is preferable to specify and manage the second-order spectrum in this wavelength range. Therefore, by satisfying the chromatic aberration correction near NIR as described above using equation (5), it becomes possible to correct axial chromatic aberration in the wavelength range from visible to NIR and SWIR without omission and with good results.

[0044] (5) Satisfying equation (5) allows for the selection of an optical material that is advantageous for correcting infrared axial aberration in the NIR range, among the aberration corrections performed by the negative lens in the rear lens group. If the upper limit condition of equation (5) is not satisfied, it becomes difficult to select an optical material from existing optical glass materials that is advantageous for both correcting aberrations for visible light and infrared light. If the lower limit condition of equation (5) is not satisfied, the correction of infrared axial chromatic aberration performed by the negative lens in the rear lens group is insufficient, which is undesirable.

[0045] More preferably, equation (5) should be set as follows: 0.830≦θtn≦0.890 (5a)

[0046] More preferably, equation (5a) should be set as follows: 0.832≦θtn≦0.875 (5aa)

[0047] More preferably, equation (5aa) should be set as follows: 0.834≦θtn≦0.866 (5aaa)

[0048] In a further embodiment of the zoom lens of the present invention, when the Abbe number of the optical material forming each of the plurality of negative lenses is νn, 50 ≤ νn ≤ 97 ···(6) The following condition is met.

[0049] Equation (6) specifies the range of Abbe numbers for the optical materials forming the multiple negative lenses included in the rear lens group of this zoom lens. Satisfying Equation (6) makes it possible to select optical materials with appropriate dispersion and partial dispersion values ​​for the negative lenses in the rear lens group. If the upper limit condition of Equation (6) is not met, the degree of freedom of selection among existing optical materials is narrow, making it difficult to correct axial chromatic aberration well from the visible to the near-infrared. If the lower limit condition of Equation (6) is not met, it is not possible to give the negative lenses an appropriate partial dispersion ratio, making it difficult to correct near-infrared axial chromatic aberration.

[0050] More preferably, equation (6) should be set as follows: 52 ≤ νn ≤ 70 ···(6a)

[0051] More preferably, equation (6a) should be set as follows: 53 ≤ νn ≤ 65 ···(6aa)

[0052] More preferably, equation (6aa) should be set as follows: 54≦νn≦61 ···(6aaa)

[0053] In a further embodiment of the zoom lens of the present invention, the Abbe number of the optical material forming the positive lens, which is arranged adjacent to or joined to the negative lens, is νp. θs=(NC-N1970) / (NF-NC) ···(a) When the first partial variance ratio defined by θsp is θsp, 55 ≤ νp ≤ 120 ···(7) 1.75 ≤ θsp ≤ 2.38 ···(8) 2.7 × 10 -3 ≦(θsn-θsp) / (νp-νn) ···(9) The following condition is met.

[0054] Equations (7) to (9) specify the conditions for the partial dispersion ratio of the optical material in each of the multiple positive lenses that are arranged adjacent to or joined to the multiple negative lenses included in the rear lens group of this zoom lens to form chromatic aberration correction. As mentioned above, three-wavelength achromatic correction is achieved by making the secondary spectrum at a predetermined wavelength zero, but the combination of optical materials with similar partial dispersion ratios for the positive and negative lenses is limited, making it difficult to correct the primary spectrum and various other aberrations represented by Seidel's five aberrations. Therefore, in the infrared chromatic aberration correction of the present invention, as shown in equations (7) to (9), low-dispersion materials are used and the chromatic aberration correction with the negative lenses is configured to be slightly excessive, making it easier to achieve an overall aberration correction balance with other lens groups, etc.

[0055] Equation (7) defines the range of Abbe numbers for multiple positive lenses included in the rear lens group. Satisfying Equation (7) allows for a larger difference in Abbe numbers between the positive and negative lenses in the rear lens group, enabling the selection of optical materials favorable for first-order chromatic aberration correction. If the upper limit condition of Equation (7) is not met, the degree of freedom in selecting existing optical materials is narrow, making it difficult to achieve good axial chromatic aberration correction from the visible to near-infrared range. If the lower limit condition of Equation (7) is not met, it is not possible to select a combination that sufficiently separates the Abbe number difference between the positive and negative lenses, making first-order spectral correction difficult.

[0056] More preferably, equation (7) should be set as follows: 58 ≤ νp ≤ 110 ···(7a)

[0057] More preferably, equation (7a) should be set as follows: 62≦νp≦100 ···(7aa)

[0058] More preferably, equation (7aa) should be set as follows: 67≦νp≦97 ···(7aaa)

[0059] (8) Satisfying equation (8) makes it possible to select a positive lens that is advantageous for near-infrared correction, even among optical materials that have low dispersion and anomalous dispersion with respect to visible light. If the upper limit of equation (8) is not satisfied, the degree of freedom of selection among existing optical materials is narrow, and it becomes difficult to correct axial chromatic aberration well from visible to near-infrared. If the lower limit of equation (8) is not satisfied, it is not possible to select a combination of existing optical materials that sufficiently separates the Abbe number difference between the positive and negative lenses, making it difficult to correct the first spectrum.

[0060] More preferably, equation (8) should be set as follows: 1.80 ≤ θsp ≤ 2.17 ···(8a)

[0061] More preferably, equation (8a) should be set as follows: 1.84≦θsp≦2.15 (8aa)

[0062] More preferably, equation (8aa) should be set as follows: 1.94≦θsp≦2.13 (8aaa)

[0063] (9) By satisfying equation (9), the ability to correct infrared chromatic aberration within the rear lens group can be maintained more efficiently. The upper limit of equation (9) is not set because, for example, combinations of positive and negative lenses with almost no Abbe number difference and a large difference in the first partial dispersion ratio are within the expected range. If the lower limit of equation (9) is not satisfied, the correction of infrared on-axis chromatic aberration within the rear lens group will be insufficient, which is undesirable.

[0064] More preferably, equation (9) should be set as follows: 5.2 × 10 -3 ≦(θsn-θsp) / (νp-νn) ···(9a)

[0065] More preferably, equation (9a) should be set as follows: 8.0×10 -3 ≦(θsn-θsp) / (νp-νn) ···(9aa)

[0066] More preferably, equation (9aa) should be set as follows: 1.5 × 10 -2 ≦(θsn-θsp) / (νp-νn) ···(9aaa)

[0067] As a further embodiment of the zoom lens of the present invention, when the average values ​​of the Abbe number νn and the first partial dispersion ratio θsn of all negative lenses included in the rear lens group are νna and θsna, respectively, and the average values ​​of the Abbe number νp and the first partial dispersion ratio θsp of all positive lenses included in the rear lens group are νpa and θspa, respectively, 0≦(θsna-θspa) / (νpa-νna)≦6.1×10 -2 ...(10) satisfies the following condition.

[0068] Equation (10) defines the relationship between the average Abbe number and the average partial variance ratio of all negative and positive lenses included in the rear lens group. Satisfying equation (10) makes it possible to achieve better secondary spectral correction for near-infrared light in the rear lens group. If the upper limit condition of equation (10) is not met, the secondary spectrum of the rear lens group for near-infrared light will be overcorrected, which is undesirable. If the lower limit condition of equation (10) is not met, the secondary spectrum of the rear lens group for near-infrared light will be undercorrected, which is undesirable.

[0069] More preferably, equation (10) should be set as follows: 4.3 × 10 -5 ≦(θsna-θspa) / (νpa-νna)≦2.0×10 -2 ...(10a)

[0070] More preferably, equation (10a) should be set as follows: 1.3 × 10-3 ≦(θsna - θspa) / (νpa - νna)≦1.5×10 -2 ···(10aa)

[0071] More preferably, the formula (10aa) should be set as follows. 1.0×10 -2 ≦(θsna - θspa) / (νpa - νna)≦1.1×10 -2 ···(10aaa)

[0072] As a further aspect of the zoom lens of the present invention, when the focal length of the rear lens group is fr and the focal length of each of the plurality of negative lenses in the single lens state is fn, in at least one of the plurality of negative lenses, -8.0≦fr / fn≦-1.2 ···(11) the conditional expression is satisfied.

[0073] (11) The formula defines the relationship between the focal length of the rear lens group and the focal length of the negative lens in the single lens state included in the rear lens group. By satisfying the formula (11), it becomes possible to give an appropriate power to the negative lens in the rear lens group, and it becomes possible to further improve the correction of the chromatic aberration on the near-infrared axis. If the upper limit condition of the formula (11) is not satisfied, it is impossible to give an appropriate power to the negative lens, resulting in insufficient correction of the chromatic aberration on the near-infrared axis, which is not preferable. If the lower limit condition of the formula (11) is not satisfied, the curvature of the negative lens becomes too tight, causing higher-order aberrations, which is not preferable.

[0074] More preferably, the formula (11) should be set as follows. -7.0≦fr / fn≦-1.3 ···(11a)

[0075] More preferably, the formula (11a) should be set as follows. -6.0≦fr / fn≦-1.4 ···(11aa)

[0076] More preferably, the formula (11aa) should be set as follows. -5.0≦fr / fn≦-1.5 (11aaa)

[0077] As a further embodiment of the zoom lens of the present invention, when the average value of fr / fn for all the negative lenses included in the rear lens group is kna, -6.0 ≤ kna ≤ -1.0 ···(12) The following condition is met.

[0078] Equation (12) defines the relationship between the focal length of each negative lens in its single-lens state within the rear lens group and the focal length of the rear lens group. By satisfying equation (12), it becomes possible to give the negative lens appropriate power to the rear lens group as a whole, and it becomes possible to correct near-infrared axial chromatic aberration well while further securing the degree of freedom for correcting other aberrations. If the upper limit condition of equation (12) is not met, it is not possible to give the negative lens appropriate power to the rear lens group as a whole, resulting in insufficient correction of near-infrared axial chromatic aberration, which is undesirable. If the lower limit condition of equation (12) is not met, the curvature of the negative lens becomes too sharp, causing higher-order aberrations, which is undesirable.

[0079] More preferably, equation (12) should be set as follows: -5.0≦kna≦-1.05 (12a)

[0080] More preferably, equation (12a) should be set as follows: -4.0≦kna≦-1.3 (12aa)

[0081] More preferably, equation (12aa) should be set as follows: -3.6≦kna≦-1.5 (12aaa)

[0082] Furthermore, the imaging device of the present invention is characterized by having a zoom lens of each embodiment and an image sensor having a predetermined effective imaging range for receiving the image formed by the zoom lens.

[0083] The specific configuration of the zoom lens of the present invention will be described below by numerical values ​​corresponding to Examples 1 to 5 and by the characteristics of the lens configurations of Examples 1 to 5. [Examples]

[0084] Figure 1 is a cross-sectional view of a zoom lens, which is Embodiment 1 of the present invention (Numerical Embodiment 1), when it is in focus at the wide-angle end and at infinity. In Figure 2, (a) shows the longitudinal aberration diagram of Numerical Embodiment 1 at the wide-angle end, (b) shows the longitudinal aberration diagram of Numerical Embodiment 1 at a focal length of 93.4 mm, and (c) shows the longitudinal aberration diagram of Numerical Embodiment 1 at the telephoto end. All aberration diagrams are longitudinal aberration diagrams when the lens is in focus at infinity. The focal length values ​​are the values ​​expressed in millimeters for the Numerical Embodiments described later. This is the same for all the Numerical Embodiments described below.

[0085] In Figure 1, the lens system has, in order from the object side to the image side, a first lens group U1 with positive refractive power for focusing. Furthermore, for zooming from the wide-angle end to the telephoto end, there is a second lens group U2 with negative refractive power for zooming that moves toward the image side, a third lens group U3 with negative refractive power that moves for zooming, and a fourth lens group U4 with positive refractive power that moves for zooming. Furthermore, there is a fifth lens group U5 with positive refractive power that moves nonlinearly along the optical axis in conjunction with the movement of the second, third, and fourth lens groups U4, and corrects image plane fluctuations associated with zooming. Furthermore, there is a sixth lens group U6 with positive refractive power that does not move for zooming and has an imaging function.

[0086] In this embodiment, the zoom system is composed of the second lens group U2, the third lens group U3, the fourth lens group U4, and the fifth lens group U5. The rear lens group corresponds to the sixth lens group U6. SP is the aperture diaphragm and is positioned between the fifth lens group U5 and the sixth lens group U6. IP is the image plane, and when used as an imaging optical system for broadcast television cameras, video cameras, and digital still cameras, it corresponds to the imaging surface of a solid-state image sensor (photoelectric conversion element) that receives light from the image formed by the zoom lens and converts it into photoelectric energy. When used as an imaging optical system for film cameras, it corresponds to the film surface to which the image formed by the zoom lens is exposed. DG is a glass block that corresponds to an optical filter or color separation optical system within the imaging device.

[0087] In the longitudinal aberration diagram, the solid, double-dashed, single-dashed, dashed, and dotted lines for spherical aberration and chromatic aberration represent the e-line, F-line, C-line, t-line, and 1970nm, respectively. The dashed and solid lines for astigmatism represent the meridional and sagittal image planes, respectively. ω is the half-angle of view, and Fno is the aperture ratio (F-number). In the longitudinal aberration diagram, spherical aberration is drawn on a scale of 1.0mm, astigmatism on 1.0mm, distortion on 5%, and chromatic aberration on 0.25mm. In each of the following embodiments, the wide-angle end and telephoto end refer to the zoom position when the second lens group U2 for zooming is located at both ends of the range in which it can move along the optical axis relative to the mechanism.

[0088] The first lens group U1 corresponds to surfaces 1 through 14. The second lens group U2 corresponds to surfaces 15 through 20. The third lens group U3 corresponds to surfaces 21 through 22. The fourth lens group U4 corresponds to surfaces 23 through 27. The fifth lens group U5 corresponds to surfaces 28 through 29. The aperture corresponds to surface 30. The sixth lens group U6 corresponds to surfaces 31 through 56. Surfaces 57 through 59 are dummy lens groups for the camera optical system.

[0089] The first lens group U1 consists of a first sub-lens group U11 with negative refractive power that does not move for focusing, a second sub-lens group U12 with positive refractive power that moves toward the image side for focusing from infinity to the near side, and a third positive sub-lens group U13 that moves toward the image side for focusing from infinity to the near side. The first sub-lens group U11 corresponds to the first to eighth surfaces, the second sub-lens group U12 corresponds to the ninth to twelfth surfaces, and the third sub-lens group U13 corresponds to the thirteenth to fourteenth surfaces.

[0090] Numerical Example 1, corresponding to Example 1 above, will now be described. In all numerical examples, not just Numerical Example 1, i indicates the order of the surfaces (optical surfaces) from the object side, ri is the radius of curvature of the i-th surface from the object side, and di indicates the distance (on the optical axis) between the i-th surface and the (i+1)-th surface from the object side. Also, ndi, νdi, θsi, and θti are the refractive index, Abbe number, first partial dispersion ratio θs defined by equation (a), and second partial dispersion ratio θt defined by equation (b) of the medium (optical material) between the i-th surface and the (i+1)-th surface, and BF represents the back focus in air equivalent. The aspherical shape is expressed by the following equation when the X-axis is in the direction of the optical axis, the H-axis is perpendicular to the optical axis, the direction of light propagation is positive, R is the radius of paraxial curvature, k is the cone constant, and A3 to A16 are aspherical coefficients. Also, "eZ" is "×10 -Z It means "...".

number

[0091] Table 1 shows the corresponding values ​​for each conditional equation in this embodiment. This embodiment satisfies equations (1) to (12) appropriately, and by appropriately setting the chromatic aberration correction and power distribution within the rear lens group, it achieves a zoom lens suitable for surveillance applications that is high-magnification, compact, lightweight, and particularly excellent in near-infrared chromatic aberration correction at the wide-angle end. For equations (3) to (9) and (11), the value closest to the lower limit among the combinations of two or more negative and positive lenses that satisfy the conditional equation is listed as a representative value.

[0092] However, while it is essential that the zoom lens of the present invention satisfies equations (1) to (4), it is not necessary to satisfy equations (5) to (12). However, if at least one of equations (5) to (12) is satisfied, an even better effect can be achieved. The same applies to other embodiments.

[0093] Figure 12 is a schematic diagram of an imaging device (television camera system) using the zoom lens of each embodiment as the imaging optical system.

[0094] In Figure 12, 101 is a zoom lens from one of Examples 1 to 5. 124 is a camera. The zoom lens 101 is detachable from the camera 124. 125 is an imaging device configured by attaching the zoom lens 101 to the camera 124. The zoom lens 101 includes a first lens group F, a zoom section LZ included in the subsequent lens group, and a rear lens group R for image formation. The first lens group F includes a focusing lens group. The zoom section LZ includes a lens group that moves along the optical axis for zooming. SP is an aperture diaphragm, which moves along the optical axis with zooming.

[0095] 114 and 115 are drive mechanisms such as helicoids and cams that drive the first lens group F and zoom section LZ in the optical axis direction, respectively. 116-118 are motors (driving means) that electrically drive the drive mechanisms 114 and 115 and the aperture diaphragm SP. 119-121 are detectors such as encoders, potentiometers, or photosensors for detecting the position of the first lens group F, zoom section LZ, and aperture diaphragm SP on the optical axis, and the aperture diameter of the aperture diaphragm SP. In camera 124, 109 is a glass block corresponding to the optical filter and color separation optical system within camera 124, and 110 is a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor that receives the subject image formed by the zoom lens 101. Also, 111 and 122 are CPUs that control various drives of camera 124 and zoom lens 101.

[0096] In this way, by applying the zoom lens of the present invention to television cameras, movie cameras, and digital still cameras, an imaging device with high optical performance can be realized. [Examples]

[0097] Figure 3 is a cross-sectional view of the zoom lens, which is Embodiment 2 of the present invention (Numerical Embodiment 2), when it is in focus at the wide-angle end and at infinity. In Figure 4, (a) shows the longitudinal aberration diagram of Numerical Embodiment 2 at the wide-angle end, (b) shows the longitudinal aberration diagram of Numerical Embodiment 2 at a focal length of 215.80 mm, and (c) shows the longitudinal aberration diagram of Numerical Embodiment 2 at the telephoto end. All of the aberration diagrams are longitudinal aberration diagrams when the lens is in focus at infinity.

[0098] In Figure 3, the lens system has a first lens group U1 with positive refractive power for focusing, arranged from the object side to the image side. Furthermore, it has a second lens group U2 with negative refractive power for zooming, which moves toward the image side for zooming from the wide-angle end to the telephoto end. Furthermore, it has a third lens group U3 with positive refractive power that moves nonlinearly along the optical axis in conjunction with the movement of the second lens group U2 to correct image plane fluctuations associated with zooming. Furthermore, it has a fourth lens group U4 with positive refractive power that does not move for zooming and has an imaging function. In this embodiment, the zoom system is composed of the second lens group U2 and the third lens group U3. The rear lens group is the fourth lens group U4. SP is the aperture diaphragm and is located in the fourth lens group U4. IP is the image plane.

[0099] The first lens group U1 corresponds to the 1st to 12th surfaces. The second lens group U2 corresponds to the 13th to 19th surfaces. The third lens group U3 corresponds to the 20th to 22nd surfaces. The fourth lens group U4 corresponds to the 23rd to 47th surfaces. The first lens group U1 consists of a first sub-lens group U11 with positive refractive power that does not move for focusing, and a second sub-lens group U12 with positive refractive power that moves toward the image side for focusing from infinity to the near side. The first sub-lens group U11 corresponds to the 1st to 8th surfaces, and the second sub-lens group U12 corresponds to the 9th to 12th surfaces.

[0100] Table 1 shows the corresponding values ​​for each conditional expression in this embodiment. This embodiment satisfies equations (1) to (12) appropriately, and by appropriately setting the chromatic aberration correction and power distribution within the rear lens group, a zoom lens suitable for surveillance applications has been achieved that is high-magnification, compact, and lightweight, and particularly excellent in near-infrared chromatic aberration correction at the wide-angle end. [Examples]

[0101] Figure 5 is a cross-sectional view of the zoom lens, which is Embodiment 3 of the present invention (Numerical Embodiment 3), when it is in focus at the wide-angle end and at infinity. In Figure 6, (a) shows the longitudinal aberration diagram of Numerical Embodiment 3 at the wide-angle end, (b) shows the longitudinal aberration diagram of Numerical Embodiment 3 at a focal length of 131.00 mm, and (c) shows the longitudinal aberration diagram of Numerical Embodiment 3 at the telephoto end. All of the aberration diagrams are longitudinal aberration diagrams when the lens is in focus at infinity.

[0102] In Figure 5, the lens system has a first lens group U1 with positive refractive power for focusing, arranged from the object side to the image side. Furthermore, it has a second lens group U2 with negative refractive power for zooming, which moves toward the image side for zooming from the wide-angle end to the telephoto end. Furthermore, it has a third lens group U3 with positive refractive power that moves nonlinearly along the optical axis in conjunction with the movement of the second lens group U2 to correct image plane fluctuations associated with zooming. Furthermore, it has a fourth lens group U4 with positive refractive power that does not move for zooming and has an imaging function. In this embodiment, the second lens group U2 and the third lens group U3 constitute the zoom system. The rear lens group is the fourth lens group U4. SP is the aperture diaphragm and is located in the fourth lens group U4. IP is the image plane.

[0103] The first lens group U1 corresponds to the first to twelfth surfaces. The second lens group U2 corresponds to the thirteenth to nineteenth surfaces. The third lens group U3 corresponds to the twenty-fifth to twenty-eighth surfaces. The aperture corresponds to the twenty-ninth surface. The fourth lens group U4 corresponds to the thirty-fifth to fifty-fourth surfaces. The first lens group U1 consists of a first sub-lens group U11 with negative refractive power that does not move for focusing, and a second sub-lens group U12 with positive refractive power that moves toward the image side for focusing from infinity to the near side. The first sub-lens group U11 corresponds to the first to eighth surfaces, and the second sub-lens group U12 corresponds to the ninth to twelfth surfaces.

[0104] Table 1 shows the corresponding values ​​for each conditional expression in this embodiment. This embodiment satisfies equations (1) to (12) appropriately, and by appropriately setting the chromatic aberration correction and power distribution within the rear lens group, a zoom lens suitable for surveillance applications has been achieved that is high-magnification, compact, and lightweight, and particularly excellent in near-infrared chromatic aberration correction at the wide-angle end. [Examples]

[0105] Figure 7 is a cross-sectional view of the zoom lens, which is Embodiment 4 (Numerical Embodiment 4) of the present invention, when it is in focus at the wide-angle end and at infinity. In Figure 8, (a) shows the longitudinal aberration diagram of Numerical Embodiment 4 at the wide-angle end, (b) shows the longitudinal aberration diagram of Numerical Embodiment 4 at a focal length of 120.00 mm, and (c) shows the longitudinal aberration diagram of Numerical Embodiment 4 at the telephoto end. All of the aberration diagrams are longitudinal aberration diagrams when the lens is in focus at infinity.

[0106] In Figure 7, the lens system has, in order from the object side to the image side, a first lens group U1 with positive refractive power for focusing. Furthermore, for zooming from the wide-angle end to the telephoto end, there is a second lens group U2 with negative refractive power for zooming that moves toward the image side, a third lens group U3 with negative refractive power that moves during zooming, and a fourth lens group U4 with positive refractive power that moves during zooming. Furthermore, there is a fifth lens group U5 with positive refractive power that moves nonlinearly along the optical axis in conjunction with the movement of the second, third, and fourth lens groups U4 to correct image plane fluctuations associated with zooming. Furthermore, there is a sixth lens group U6 with positive refractive power that does not move for zooming and has an imaging function. In this embodiment, the zoom system is composed of the second, third, fourth, and fifth lens groups U2, U3, U4, and U5. The rear lens group corresponds to the sixth lens group U6. SP is the aperture diaphragm, located between the fifth lens group U5 and the sixth lens group U6. IP is the image plane.

[0107] The first lens group U1 corresponds to surfaces 1 through 12. The second lens group U2 corresponds to surfaces 13 through 18. The third lens group U3 corresponds to surfaces 19 through 20. The fourth lens group U4 corresponds to surfaces 21 through 23. The fifth lens group U5 corresponds to surfaces 24 through 25. The aperture corresponds to surface 26. The sixth lens group U6 corresponds to surfaces 27 through 49. Surfaces 50 through 52 are dummy lens groups for the camera optical system. The first lens group U1 consists of a first sub-lens group U11 with negative refractive power that does not move for focusing, and a second sub-lens group U12 with positive refractive power that moves towards the image side for focusing from infinity to the near side. The first sub-lens group U11 corresponds to surfaces 1 through 8, and the second sub-lens group U12 corresponds to surfaces 9 through 12.

[0108] Table 1 shows the corresponding values ​​for each conditional expression in this embodiment. This embodiment satisfies equations (1) to (12) appropriately, and by appropriately setting the chromatic aberration correction and power distribution within the rear lens group, a zoom lens suitable for surveillance applications has been achieved that is high-magnification, compact, and lightweight, and particularly excellent in near-infrared chromatic aberration correction at the wide-angle end. [Examples]

[0109] Figure 9 is a cross-sectional view of the zoom lens, which is Embodiment 5 of the present invention (Numerical Embodiment 5), when it is in focus at the wide-angle end and at infinity. In Figure 10, (a) shows the longitudinal aberration diagram of Numerical Embodiment 5 at the wide-angle end, (b) shows the longitudinal aberration diagram of Numerical Embodiment 5 at a focal length of 154.80 mm, and (c) shows the longitudinal aberration diagram of Numerical Embodiment 5 at the telephoto end. All of the aberration diagrams are longitudinal aberration diagrams when the lens is in focus at infinity.

[0110] In Figure 9, the lens system has a first lens group U1 with positive refractive power for focusing, arranged in order from the object side to the image side. Furthermore, it has a second lens group U2 with negative refractive power for zooming, which moves toward the image side for zooming from the wide-angle end to the telephoto end. Furthermore, it has a third lens group U3 with positive refractive power that moves nonlinearly along the optical axis in conjunction with the movement of the second lens group U2 to correct image plane fluctuations associated with zooming. Furthermore, it has a fourth lens group U4 with positive refractive power that does not move for zooming and has an imaging function. In this embodiment, the second lens group U2 and the third lens group U3 constitute the zoom system. The rear lens group corresponds to the fourth lens group U4. SP is the aperture diaphragm and is located between the third lens group U3 and the fourth lens group U4. IP is the image plane.

[0111] The first lens group U1 corresponds to surfaces 1 through 12. The second lens group U2 corresponds to surfaces 13 through 19. The third lens group U3 corresponds to surfaces 20 through 28. The aperture diaphragm corresponds to surface 29. The fourth lens group U4 corresponds to surfaces 30 through 54. Surfaces 55 through 57 are dummy lens groups for the camera optical system. The first lens group U1 consists of a first sub-lens group U11 with negative refractive power that does not move for focusing, and a second sub-lens group U12 with positive refractive power that moves towards the image side for focusing from infinity to the near side. The first sub-lens group U11 corresponds to surfaces 1 through 8, and the second sub-lens group U12 corresponds to surfaces 9 through 12.

[0112] Table 1 shows the corresponding values ​​for each conditional expression in this embodiment. This embodiment satisfies equations (1) to (12) appropriately, and by appropriately setting the chromatic aberration correction and power distribution within the rear lens group, a zoom lens suitable for surveillance applications has been achieved that is high-magnification, compact, and lightweight, and particularly excellent in near-infrared chromatic aberration correction at the wide-angle end.

[0113] <Numerical Example 1> Unit: mm Surface data Face number rd nd vd θs θt 1 247.138 3.00 1.85150 40.8 1.5790 0.7390 2 133.165 1.26 3 132.802 11.40 1.43387 95.1 1.9585 0.8091 4 669.149 5.33 5 -2470.405 3.00 1.51633 64.1 2.3893 0.8687 6 184.859 2.78 7 203.652 12.13 1.43387 95.1 1.9585 0.8091 8 -596.377 12.48 9 296.752 6.85 1.43387 95.1 1.9585 0.8091 10 1283.579 0.20 11 141.890 15.62 1.43387 95.1 1.9585 0.8091 12 -811.464 4.13 13 114.044 6.82 1.43875 94.7 2.1296 0.8410 14 194.511 (variable) 15 103.818 1.00 2.00100 29.1 1.3159 0.6838 16 24.062 10.06 17 -34.726 0.90 1.43875 94.9 2.1017 0.8373 18 49.334 1.28 19 40.427 8.15 1.85478 24.8 1.3095 0.8739 20 -61.575 (variable) 21 -38.262 1.10 1.65160 58.5 2.2947 0.8525 22* 88.021 (variable) 23 -79.009 1.00 1.81600 46.6 1.7383 0.7690 24 72.870 4.34 1.85478 24.8 1.3095 0.8739 25 -107.623 0.86 26 -70.723 1.00 1.89190 37.1 1.4800 0.7140 27 -414.367 (variable) 28* 141.889 5.77 1.64000 60.1 2.3803 0.8645 29 -55.992 (variable) 30 (aperture) ∞ 1.22 31 113.572 3.68 1.59522 67.7 1.8476 0.7953 32 214.632 0.20 33 68.348 7.64 1.49700 81.5 2.0443 0.8258 34 -62.345 1.30 1.80810 22.8 1.2887 0.6596 35 217.090 1.94 36 274.040 1.30 1.77250 49.6 1.9229 0.7955 37 64.494 0.80 38 43.720 4.18 1.80810 22.8 1.2887 0.6596 39 73.669 5.53 40 476.847 3.30 1.88300 40.8 1.5660 0.7397 41 -364.853 1.99 42 388.560 1.78 1.51633 64.1 2.3901 0.7953 43 106.026 40.38 44 67.109 5.35 1.43875 94.9 2.1017 0.8410 45 -47.992 0.50 46 63.062 5.90 1.43875 94.9 2.1017 0.8410 47 -30.033 1.20 1.64000 60.1 2.3803 0.8645 48 52.050 20.00 49 -26.789 1.20 1.65160 58.5 2.2947 0.8525 50 -41.033 16.49 51 44.654 1.20 1.88300 40.8 1.5660 0.7397 52 21.883 8.87 1.56732 42.8 1.7442 0.7589 53 -78.203 3.36 54 -35.177 4.49 1.43875 94.9 2.1017 0.8373 55 -19.665 1.20 1.65160 58.5 2.2947 0.8525 56 -24.163 4.87 57 ∞ 33.00 1.60859 46.4 1.8423 0.7750 58 ∞ 13.20 1.51680 64.2 2.3351 0.8687 59 ∞ 8.10 Image plane ∞

[0114] Aspherical data Page 22 K = 0.00000e+00 A 4=-1.27407e-06 A 6= 8.94995e-10 A 8= 2.30993e-11 A10=7.95369e-14 A12=-9.12510e-16 Page 28 K =-5.07198e+00 A 4=-8.97124e-07 A 6= 1.59409e-10 A 8=-7.09152e-13 A10= 1.86675e-15 A12=-2.09687e-18

[0115] Various data Zoom ratio 43.60 Focal length 14.00 93.40 610.50 F-numbers: 2.87, 2.89, 5.63 Half-angle 21.45 3.37 0.52 Lens length 472.53 472.53 472.53 BF 8.10 8.10 8.10 d14 3.49 93.70 124.58 d20 4.79 5.91 7.11 d22 127.79 9.14 10.74 d27 7.63 28.49 1.00 d29 4.21 10.66 4.47

[0116] Entrance pupil position 106.09 598.79 2778.15 Exit pupil position 197.65 197.65 197.65 Front principal point position 121.12 738.22 5354.97 Back principal point position -5.90 -85.30 -602.41

[0117] Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 167.06 85.00 52.10 -13.54 2 15 -118.28 21.39 -31.20 -66.01 3 21 -40.62 1.10 0.20 -0.46 4 23 -80.86 7.20 1.18 -3.04 5 28 63.20 5.77 2.55 -1.00 6 30 96.58 196.06 148.61 -78.23

[0118] Single lens data Lens starting plane, focal length 1 1 -341.29 2 3 378.48 3 5 -331.74 4 7 350.63 5 9 885.55 6 11 279.05 7 13 610.93 8 15 -31.23 9 17 -46.18 10 19 29.37 11 21 -40.62 12 23 -46.08 13 24 50.92 14 26 -95.14 15 28 63.20 16 31 398.39 17 33 66.71 18 34 -59.20 19 36 -108.96 20 38 123.95 21 40 233.16 22 42 -281.96 23 44 64.53 24 46 47.17 25 47 -29.47 26 49 -122.03 27 51 -49.55 28 52 30.97 29 54 93.14 30 55 -180.48 31 57 0.00 32 58 0.00

[0119] <Numerical Example 2> Unit: mm Surface data Face number rd nd vd θs θt 1 204.747 14.36 1.48749 70.2 2.5490 0.8924 2 -636.913 1.00 3 141.341 3.70 1.77250 49.6 1.9229 0.7955 4 95.018 4.09 5 92.999 22.20 1.43387 95.1 1.9585 0.8091 6 -593.374 1.50 7 -385.860 3.20 1.72916 54.7 2.1057 0.8244 8 168.863 19.04 9 148.673 13.30 1.43387 95.1 1.9585 0.8091 10 -588.610 0.15 11 164.597 7.00 1.43875 94.9 2.1017 0.8373 12 324.962 (variable) 13 25961.799 1.20 1.61800 63.3 1.9662 0.8194 14 26.724 5.73 15 278.486 1.00 1.59522 67.7 1.8476 0.7953 16 25.808 8.36 1.72047 34.7 1.5610 0.7267 17 -212.609 3.69 18 -52.427 1.00 1.62041 60.3 2.1215 0.8291 19* 316.610 (variable) 20 -70.751 1.15 1.71700 47.9 1.7072 0.7629 21 67.832 4.23 1.80810 22.8 1.2887 0.6596 22 519.661 (variable) 23* 157.672 7.34 1.49700 81.5 2.0443 0.8258 24 -83.727 0.20 25 44.980 9.90 1.59522 67.7 1.8476 0.7653 26 -140.909 0.61 27 95.492 6.96 1.49700 81.5 2.0443 0.8258 28 -65.697 1.00 1.64000 60.1 2.3803 0.8645 29 379.038 0.50 30 119.366 6.29 1.43875 94.9 2.1017 0.8410 31 -77.735 1.20 2.00100 29.1 1.3159 0.6838 32 126.986 4.06 33 (aperture) ∞ 32.49 34 -29.774 2.25 1.59522 67.7 1.8476 0.7953 35 -22.040 1.20 1.64000 60.1 2.3803 0.8645 36 -56.192 37.35 37 1798.372 6.80 1.58144 40.8 1.7446 0.7500 38 -27.738 1.84 39 -25.849 2.84 1.49700 81.5 2.0443 0.8258 40 -21.205 1.20 1.64000 60.1 2.3803 0.8645 41 -140.090 3.00 42 145.064 7.68 1.68893 31.1 1.4380 0.6995 43 -27.983 1.20 2.00100 29.1 1.3159 0.6838 44 -626.893 2.43 45 -62.536 4.20 1.80518 25.4 1.2802 0.6680 46 -30.329 1.20 1.95906 17.5 1.1610 0.6264 47 -34.458 52.00 Image plane ∞

[0120] Aspherical data Page 19 K =-1.15564e+02 A 4=-3.55965e-06 A 6=-1.12271e-07 A 8=-5.29940e-09 A10=-2.21323e-11 A12= 3.15317e-13 A14= 2.53426e-16 A 3=-1.15915e-07 A 5= 2.92916e-07 A 7= 2.88344e-08 A 9= 5.78631e-10 A11=-2.23335e-12 A13=-1.47760e-14 Page 23 K =-1.37989e+02 A 4= 1.07833e-06 A 6=-1.21967e-07 A 8=-7.11545e-10 A10=-1.68143e-12 A12=-1.52419e-15 A14=-2.12777e-19 A 3= 4.12526e-06 A 5= 7.03155e-07 A 7= 1.09923e-08 A 9= 3.76626e-11 A11= 5.94565e-14 A13= 2.55061e-17

[0121] Various data Zoom ratio 19.20 Focal length 50.00 215.80 960.00 F-number 4.66 4.66 8.32 Half-angle 16.49 3.92 0.88 Lens length 454.50 454.50 454.50 BF 52.00 52.00 52.00 d12 2.87 89.38 127.53 d19 124.82 64.50 4.30 d22 15.19 29.03 1.13

[0122] Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 215.83 89.33 31.09 -44.81 2 13 -35.23 20.90 4.88 -9.72 3 20 -95.95 5.32 0.36 -2.60 4 23 87.12 144.34 42.56 -245.50

[0123] Single lens data Lens starting plane, focal length 1 1 320.90 2 3 -383.29 3 5 183.83 4 7 -161.84 5 9 281.51 6 11 751.12 7 13 -43.27 8 15 -47.22 9 16 32.35 10 18 -73.69 11 20 -48.17 12 21 96.71 13 23 113.94 14 25 57.75 15 27 76.99 16 28 -82.72 17 30 108.61 18 31 -48.81 19 34 131.11 20 35 -56.09 21 37 46.40 22 39 193.93 23 40 -39.21 24 42 33.79 25 43 -28.46 26 45 65.49 27 46 -263.02

[0124] <Numerical Example 3> Unit: mm Surface data Face number rd nd vd θs θt 1 682.120 6.00 1.65100 56.2 2.1701 0.8345 2 349.658 0.69 3 311.309 24.40 1.43387 95.1 1.9585 0.8091 4 -1141.080 1.08 5 593.873 6.00 1.65412 39.7 1.7312 0.7554 6 221.900 1.13 7 227.284 24.79 1.43387 95.1 1.9585 0.8091 8 4587.883 27.40 9 354.382 11.97 1.43387 95.1 1.9585 0.8091 10 1027.840 7.36 11 163.661 20.78 1.49700 81.5 2.0443 0.8258 12 435.326 (variable) 13* 18073.629 2.20 2.00330 28.3 1.3128 0.6842 14 38.948 10.71 15 -49.833 1.45 1.78800 47.4 1.8521 0.7837 16 65.375 9.79 1.92286 18.9 1.1923 0.6365 17 -73.963 2.43 18 -47.115 2.00 1.65412 39.7 1.7312 0.7554 19 -91.990 (variable) 20 108.145 13.98 1.59522 67.7 1.8476 0.7953 21* -405.597 0.50 22 122.302 13.07 1.59522 67.7 1.8476 0.7953 23 -427.633 0.20 24 188.006 2.50 1.80518 25.4 1.2802 0.6680 25 58.257 19.05 1.49700 81.5 2.0443 0.8258 26 -5572.127 0.50 27 468.507 6.40 1.59522 67.7 1.8476 0.7953 28* -348.612 (variable) 29 (aperture) ∞ 4.87 30 -202.173 1.40 1.88300 40.8 1.5660 0.7397 31 52.889 1.24 32 38.100 4.67 1.80810 22.8 1.2887 0.6596 33 255.029 4.05 34 -81.247 1.40 1.81600 46.6 1.7383 0.7690 35 120.494 4.26 36 43.554 2.11 1.59522 67.7 1.8476 0.7953 37 54.033 7.76 38 -55.739 1.20 1.95906 17.5 1.1610 0.6264 39 -47.708 4.90 40 -49.090 3.19 1.49700 81.5 2.0443 0.8258 41 -29.737 4.38 42 -40.964 1.20 1.64000 60.1 2.3803 0.8645 43 -1448.450 7.29 44 189.447 3.25 1.59522 67.7 1.8476 0.7953 45 -49.047 1.20 1.64000 60.1 2.3803 0.8645 46 70.373 3.80 47 1607.246 5.50 1.48749 70.2 2.5490 0.8924 48 -18.187 1.20 1.65160 58.5 2.2947 0.8525 49 -39.949 0.88 50 -1526.927 5.04 1.59522 67.7 1.8476 0.7953 51 -21.552 1.20 1.64000 60.1 2.3803 0.8645 52 -128.912 0.04 53 46.971 4.09 1.48749 70.2 2.5490 0.8924 54 -78.289 10.00 55 ∞ 33.00 1.60859 46.4 1.8423 0.7750 56 ∞ 13.20 1.51680 64.2 2.3351 0.8687 57 ∞ 13.85 Image plane ∞

[0125] Aspherical data Page 13 K = 0.00000e+00 A 4= 7.47758e-07 A 6= 9.29456e-09 A 8= 2.21240e-10 A10= 1.75675e-12 A12= 5.18281e-15 A14= 3.78662e-18 A16= 3.15661e-22 A 3= 3.04852e-07 A 5=-2.28681e-08 A 7=-1.75909e-09 A 9=-2.18764e-11 A11=-1.10726e-13 A13=-1.71256e-16 A15=-5.08309e-20 The 21st surface K = 0.00000e+00 A 4= 2.26284e-07 A 6=-1.92133e-11 A 8= 8.65737e-14 A10=-9.68992e-17 A12= 2.63049e-20 A14= 1.48323e-25 A16= 5.54447e-27 A 3=-1.41344e-07 A 5= 8.13212e-10 A 7=-1.39508e-12 A 9= 3.33879e-16 A11= 1.30310e-18 A13=-3.70836e-22 A15=-3.24743e-25 The 28th surface K = 0.00000e+00 A 4= 5.46711e-07 A 6= 7.38787e-09 A 8= 1.45148e-11 A10=-1.16264e-14 A12= 1.20199e-17 A14=-2.51373e-20 A16=-4.23103e-24 A 3= 9.89211e-09 A 5=-5.88461e-08 A 7=-4.82342e-10 A 9= 3.61333e-14 A11=-5.51003e-17 A13= 2.11899e-19 A15= 5.65576e-22

[0126] Various data Zoom ratio 92.10 Focal length 12.80 131.00 1175.20 F-number 2.44 2.44 5.81 Half angle of view 23.32 2.40 0.27 Overall lens length 669.69 669.69 669.69 BF 13.85 13.85 13.85 d12 18.53 168.53 204.82 d19 281.61 102.00 -5.56 d28 3.00 32.61 103.88 Entrance pupil position 193.30 1430.24 14723.23 Exit pupil position 281.86 281.86 281.86 Front principal point position 206.66 1625.36 21051.56 Rear principal point position 1.09 -117.19 -1161.35

[0127] Zoom lens group data Group Starting surface Focal length Lens configuration length Front principal point position Rear principal point position 1 1 293.10 131.60 61.61 -42.93 2 13 -29.05 28.58 2.50 -18.83 3 20 71.76 56.20 11.33 -27.36 4 29 53.21 136.32 66.87 21.40

[0128] Single lens data Lens Starting surface Focal length 1 1 -1105.23 2 3 565.19 3 5 -541.86 4 7 548.83 5 9 1236.82 6 11 513.08 7 13 -38.58 8 15 -35.51 9 16 38.45 10 18 -149.42 11 20 144.41 12 22 160.64 13 24 -104.78 14 25 115.80 15 27 335.62 16 30 -47.08 17 32 54.34 18 34 -58.98 19 36 349.60 20 38 477.88 21 40 143.46 22 42 -65.63 23 44 65.56 24 45 -44.81 25 47 36.81 26 48 -52.16 27 50 36.55 28 51 -40.45 29 53 60.67 30 55 0.00 31 56 0.00

[0129] 〈Numerical Example 4〉 Unit: mm Surface data Surface number r d nd vd θs θt 1 245.391 3.00 1.85150 40.8 1.5790 0.7392 2 130.602 0.59 3 124.136 12.30 1.43387 95.1 1.9585 0.8091 4 457.274 0.50 5 269.236 3.00 1.51633 64.1 2.3901 0.8687 6 131.716 2.45 7 142.838 11.71 1.43387 95.1 1.9585 0.8091 8 770.032 12.82 9 185.207 15.23 1.43387 95.1 1.9585 0.8091 10 -463.061 0.20 11 109.059 11.72 1.43387 95.1 1.9585 0.8091 12 273.810 (variable) 13 400.000 1.00 2.00100 29.1 1.3159 0.6838 14 27.103 8.22 15 -37.144 0.90 1.51633 64.1 2.3901 0.8687 16 -65.161 2.00 17 52.734 6.50 1.85478 24.8 1.3095 0.6739 18 -63.260 (variable) 19 -40.431 1.10 1.65160 58.5 2.2947 0.8525 20 * 48.323 (variable) 21 -54.438 1.00 1.81600 46.6 1.7383 0.7690 22 54.335 3.46 1.85478 24.8 1.3095 0.6739 23 -1420.139 (variable) 24* 173.613 5.61 1.59522 67.7 1.8476 0.7953 25 -55.992 (variable) 26 (aperture) ∞ 1.22 27 135.204 4.85 1.49700 81.5 2.0443 0.8258 28 -239.235 0.20 29 36.194 7.99 1.59522 67.7 1.8476 0.7953 30 -209.938 1.30 1.80810 22.8 1.2887 0.6596 31 86.146 1.94 32 90.271 1.30 1.69680 55.5 2.1665 0.8330 33 28.392 0.80 34 28.097 2.75 1.65412 39.7 1.7312 0.7554 35 34.047 5.53 36 -146.752 1.80 1.65160 58.5 2.2947 0.8525 37 -872.689 35.00 38 32.013 6.91 1.59522 67.7 1.8476 0.7953 39 -103.038 2.02 40 89.675 3.54 1.43875 94.9 2.1017 0.8410 41 -74.766 1.20 1.64000 60.1 2.3803 0.8645 42 -2576.591 3.82 43 -26.593 1.20 1.65160 58.5 2.2947 0.8525 44 -43.007 4.13 45 -145.035 1.20 1.88300 40.8 1.5660 0.7397 46 16.882 6.92 1.56732 42.8 1.7442 0.7589 47 -17.782 3.00 48 -20.322 1.20 1.65160 58.5 2.2947 0.8525 49 -140.037 4.87 50 ∞ 33.00 1.60859 46.4 1.8423 0.7750 51 ∞ 13.20 1.51680 64.2 2.3351 0.8687 52 ∞ 10.00 Image plane ∞

[0130] Aspherical data Page 20 K = 0.00000e+00 A 4=-3.95154e-06 A 6=-3.50703e-08 A 8= 5.02922e-10 A10=-3.39674e-12 A12= 8.83762e-15 Page 24 K =-5.07198e+00 A 4=-8.38686e-07 A 6= 2.41407e-09 A 8=-1.50165e-11 A10=4.40195e-14 A12=-4.74850e-17

[0131] Various data Zoom ratio 44.50 Focal length 18.00 120.00 800.00 F-number 3.50 3.50 7.00 Half-angle 17.01 2.62 0.39 Lens length 436.07 436.07 436.07 BF 10.00 10.00 10.00 d12 4.13 94.35 125.23 d18 15.19 16.32 17.52 d20 126.26 11.57 18.04 d23 16.46 33.36 0.99 d25 9.81 16.25 10.07 Entrance pupil position 111.33 660.44 3332.70 Exit pupil position -90.64 -90.64 -90.64 Front principal point position 126.09 637.35 -2226.35 Back principal point position -7.98 -110.00 -790.00

[0132] Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 177.02 73.52 39.83 -16.34 2 13 1280.28 18.63 417.22 597.05 3 19 -33.48 1.10 0.30 -0.36 4 21 -73.29 4.46 -0.14 -2.55 5 24 71.53 5.61 2.68 -0.86 6 26 128.96 150.90 -31.75 -116.12

[0133] Single lens data Lens starting plane, focal length 1 1 -329.97 2 3 387.41 3 5 -501.32 4 7 400.91 5 9 306.33 6 11 407.91 7 13 -28.85 8 15 -168.54 9 17 34.22 10 19 -33.48 11 21 -33.02 12 22 60.71 13 24 71.53 14 27 174.05 15 29 52.32 16 30 -74.67 17 32 -59.70 18 34 206.46 19 36 -269.91 20 38 41.69 21 40 93.31 22 41 -119.86 23 43 -109.67 24 45 -16.97 25 46 16.37 26 48 -36.48 27 50 0.00 28 51 0.00

[0134] <Numerical Example 5> Unit: mm Surface data Face number rd nd vd θs θt 1 600.879 6.00 1.64000 60.1 2.3803 0.8645 2 333.619 0.50 3 311.805 28.32 1.43387 95.1 1.9585 0.8091 4 -801.556 1.00 5 516.417 6.00 1.65412 39.7 1.7312 0.7554 6 213.809 0.56 7 214.295 23.19 1.43387 95.1 1.9585 0.8091 8 1088.271 26.62 9 261.421 16.51 1.43387 95.1 1.9585 0.8091 10 978.660 5.24 11 168.688 17.83 1.49700 81.5 2.0443 0.8258 12 373.075 (variable) 13* 18073.629 2.00 2.00330 28.3 1.3128 0.6842 14 43.149 12.00 15 -37.880 1.40 1.78800 47.4 1.8521 0.7837 16 -2068.503 9.70 1.95906 17.5 1.1610 0.6264 17 -51.340 1.20 18 -56.568 2.00 1.77250 49.6 1.9229 0.7955 19 -212.324 (variable) 20 100.457 14.00 1.59522 67.7 1.8476 0.7953 21* -405.597 0.50 22 135.729 12.00 1.59522 67.7 1.8476 0.7953 23 -846.967 0.20 24 257.076 2.50 1.85478 24.8 1.3095 0.6739 25 64.828 18.00 1.59522 67.7 1.8476 0.7953 26 -686.442 0.50 27 303.751 6.50 1.59522 67.7 1.8476 0.7953 28* -800.000 (variable) 29 (aperture) ∞ 4.87 30 -433.158 1.40 1.88300 40.8 1.5660 0.7397 31 58.721 1.24 32 36.715 4.67 1.80810 22.8 1.2887 0.6596 33 243.948 4.05 34 -118.468 1.40 1.81600 46.6 1.7383 0.7690 35 99.411 4.50 36 37.644 3.80 1.49700 81.5 2.0443 0.8258 37 210.238 3.92 38 75.769 1.20 1.67790 55.4 2.1192 0.8271 39 25.059 6.23 40 -64.374 3.50 1.49700 81.5 2.0443 0.8258 41 -25.982 6.00 42 -34.155 1.20 1.67790 55.4 2.1192 0.8271 43 -10405.572 7.31 44 148.810 3.77 1.52841 76.5 1.9913 0.8175 45 -51.580 1.20 1.64000 60.1 2.3803 0.8645 46 47.311 3.20 47 58.063 4.80 1.48749 70.2 2.5490 0.8924 48 -23.263 1.20 1.65160 58.5 2.2947 0.8525 49 -52.336 4.57 50 170.633 5.70 1.52841 76.5 1.9913 0.8175 51 -20.435 1.20 1.64000 60.1 2.3803 0.8645 52 -124.040 3.31 53 129.758 3.30 1.48749 70.2 2.5490 0.8924 54 -43.345 10.00 55 ∞ 33.00 1.60859 46.4 1.8423 0.7750 56 ∞ 13.20 1.51680 64.2 2.3351 0.8687 57 ∞ 13.85 Image plane ∞

[0135] Aspherical data Page 13 K = 0.00000e+00 A 4= 7.47758e-07 A 6= 9.29456e-09 A 8= 2.21240e-10 A10= 1.75675e-12 A12= 5.18281e-15 A14= 3.78662e-18 A16= 3.15661e-22 A 3= 3.04852e-07 A 5=-2.28681e-08 A 7=-1.75909e-09 A 9=-2.18764e-11 A11=-1.10726e-13 A13=-1.71256e-16 A15=-5.08309e-20 Page 21 K = 0.00000e+00 A 4= 2.26284e-07 A 6=-1.92133e-11 A 8= 8.65737e-14 A10=-9.68992e-17 A12= 2.63049e-20 A14= 1.48323e-25 A16= 5.54447e-27 A 3=-1.41344e-07 A 5= 8.13212e-10 A 7=-1.39508e-12 A 9= 3.33879e-16 A11= 1.30310e-18 A13=-3.70836e-22 A15=-3.24743e-25 Page 28 K = 0.00000e+00 A 4= 5.46711e-07 A 6= 7.38787e-09 A 8= 1.45148e-11 A10=-1.16264e-14 A12= 1.20199e-17 A14=-2.51373e-20 A16=-4.23103e-24 A 3= 9.89211e-09 A 5=-5.88461e-08 A 7=-4.82342e-10 A 9= 3.61333e-14 A11=-5.51003e-17 A13= 2.11899e-19 A15= 5.65576e-22

[0136] Various data Zoom ratio 92.00 Focal length 15.00 154.80 1380.00 F-numbers: 2.79, 2.80, 6.50 Half-angle 20.14 2.03 0.23 Lens length 663.26 663.26 663.26 BF 13.85 13.85 13.85 d12 2.00 152.00 188.29 d19 286.19 107.11 3.75 d28 3.22 32.29 99.36 Entrance pupil position 164.15 1288.95 11895.41 Exit pupil position 490.72 490.72 490.72 Front principal point position 179.62 1493.98 17268.90 Back principal point position -1.15 -140.94 -1366.15

[0137] Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 278.36 131.77 58.27 -45.79 2 13 -27.43 28.30 3.42 -17.54 3 20 71.32 54.20 10.98 -25.39 4 29 71.55 143.73 85.43 50.39

[0138] Single lens data Lens starting plane, focal length 1 1 -1177.70 2 3 520.11 3 5 -558.90 4 7 608.59 5 9 814.40 6 11 600.31 7 13 -42.75 8 15 -48.74 9 16 54.04 10 18 -99.91 11 20 136.20 12 22 196.75 13 24 -101.07 14 25 100.06 15 27 369.39 16 30 -58.15 17 32 52.41 18 34 -65.71 19 36 91.32 20 38 -55.53 21 40 84.83 22 42 -50.33 23 44 72.74 24 45 -38.22 25 47 34.63 26 48 -65.07 27 50 34.79 28 51 -38.25 29 53 66.84 30 55 0.00 31 56 0.00

[0139] [Table 1]

[0140] This embodiment includes the following configuration. (Composition 1) A zoom lens having, in order from the object side to the image side, a first lens group with positive refractive power that does not move for zooming, a plurality of moving lens groups including at least one lens group with negative refractive power, and a rear lens group with positive refractive power that does not move for zooming, The spacing between adjacent lens groups changes for zooming purposes. When the focal length of the zoom lens at infinity focus and the wide-angle end is fw, the focal length of the zoom lens at infinity focus and the telephoto end is ft, the focal length of the first lens group is f1, and the maximum aperture F-number of the zoom lens at the wide-angle end is Fnw, 3.5 ≤ ft / f1 ≤ 6.0 4.7 ≤ fw / Fnw ≤ 12.0 The following conditions are met: When the refractive indices of the material for the C line, F line, and 1970 nm wavelengths are NC, NF, and N1970, respectively, the first partial dispersion ratio θs is: θs = (NC - N1970) / (NF - NC) Defined by, The aforementioned rear lens group, when the refractive index with respect to the d line is Ndn and the first partial dispersion ratio is θsn, 1.55 ≤ Ndn ≤ 1.75 2.10 ≤ θsn ≤ 2.60 A zoom lens characterized by including multiple negative lenses formed from materials that satisfy the following condition. (Configuration 2) When the refractive indices for the C, F, and t lines are NC, NF, and Nt, respectively, the second partial dispersion ratio θt is: θt = (NC - Nt) / (NF - NC) Defined by, When the second partial dispersion ratio of the material forming the plurality of negative lenses is θtn, 0.825 ≤ θtn ≤ 0.900 A zoom lens according to configuration 1, characterized in that it satisfies the following condition. (Composition 3) When the Abbe number of the material forming the plurality of negative lenses is νn, 50 ≤ νn ≤ 97 A zoom lens according to configuration 1 or 2, characterized in that it satisfies the following condition. (Composition 4) When the Abbe number of the material that is included in the rear lens group and forms a positive lens positioned next to any of the plurality of negative lenses is νp, 55≦νp≦120 A zoom lens according to any one of configurations 1 to 3, characterized by including a plurality of positive lenses formed from a material that satisfies the following condition. (Composition 5) When the first partial dispersion ratio of the material forming the plurality of positive lenses is θsp, 1.75 ≤ θsp ≤ 2.38 The zoom lens described in configuration 4, characterized in that it satisfies the following condition. (Composition 6) The aforementioned rear lens group includes a plurality of pairs of negative lenses included in the plurality of negative lenses and positive lenses positioned next to the negative lenses, When the Abbe number of the material forming the plurality of negative lenses is νn, the Abbe number of the material forming the plurality of positive lenses is νp, and the first partial dispersion ratio is θsp, 2.7 × 10 -3 ≤(θsn-θsp) / (νp-νn) A zoom lens according to any one of configurations 1 to 5, characterized in that it satisfies the following conditional expression. (Composition 7) When the average value of the Abbe number νn of all materials forming negative lenses in the rear lens group is νna, the average value of the first partial dispersion ratio of all materials forming negative lenses in the rear lens group is θsna, the average value of the Abbe number νp of all materials forming positive lenses in the rear lens group is νpa, and the average value of the first partial dispersion ratio of all materials forming positive lenses in the rear lens group is θspa, 0≦(θsna-θspa) / (νpa-νna)≦6.1×10 -2 A zoom lens according to any of configurations 1 to 6, characterized in that it satisfies the following condition. (Composition 8) When the focal length of the rear lens group is fr and the focal length of the negative lens included in the plurality of negative lenses is fn, the plurality of negative lenses are -8.0 ≤ fr / fn ≤ -1.2 A zoom lens according to any one of claims 1 to 7, characterized in that it includes a negative lens that satisfies the following condition. (Composition 9) When the focal length of the rear lens group is fr, the focal length of the negative lens included in the plurality of negative lenses is fn, and the average value of fr / fn for the plurality of negative lenses is kna, -6.0 ≤ kna ≤ -1.0 A zoom lens according to any of configurations 1 to 8, characterized in that it satisfies the following condition. (Composition 10) An imaging device characterized by having a zoom lens as described in any of configurations 1 to 9, and an image sensor for capturing an image formed by the zoom lens. Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its gist. The feature of the present invention is to appropriately set the power arrangement of the zoom lens and the characteristics of the optical materials used in each group, and the effects of the present invention can be achieved even if the other components of the zoom lens are different from the configurations of numerical examples 1 to 5. [Explanation of symbols]

[0141] U1 First Lens Group U2 Second Lens Group U3 Third Lens Group U4 4th lens group U5 5th lens group U6 6th lens group

Claims

1. A zoom lens comprising, in order from the object side to the image side, a first lens group with positive refractive power that does not move for zooming, a plurality of moving lens groups including at least one lens group with negative refractive power, and a rear lens group with positive refractive power that does not move for zooming, The spacing between adjacent lens groups changes for zooming purposes. When the focal length of the zoom lens at infinity focus and the wide-angle end is fw, the focal length of the zoom lens at infinity focus and the telephoto end is ft, the focal length of the first lens group is f1, and the maximum aperture F-number of the zoom lens at the wide-angle end is Fnw, 3.5 ≤ ft / f1 ≤ 6.0 4.7 ≤ fw / Fnw ≤ 12.0 The following conditions are met: When the refractive indices of the materials for wavelengths of C, F, and 1970 nm are NC, NF, and N1970, respectively, the first partial dispersion ratio θs is: θs=(NC-N1970) / (NF-NC) Defined by, The aforementioned rear lens group, when the refractive index with respect to the d line is Ndn and the first partial dispersion ratio is θsn, 1.55 ≤ Ndn ≤ 1.75 2.10 ≤ θsn ≤ 2.60 It includes multiple negative lenses formed from materials that satisfy the following condition: When the Abbe number of the material that is included in the rear lens group and forms a positive lens positioned next to any of the plurality of negative lenses is νp, 55 ≤ νp ≤ 120 A zoom lens characterized by including multiple positive lenses formed from materials that satisfy the following condition.

2. When the refractive indices for the C, F, and t lines are NC, NF, and Nt respectively, the second partial dispersion ratio θt is: θt=(NC-Nt) / (NF-NC) Defined by, When the second partial dispersion ratio of the material forming the plurality of negative lenses is θtn, 0.825 ≤ θtn ≤ 0.900 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

3. When the Abbe number of the material forming the plurality of negative lenses is νn, 50 ≤ νn ≤ 97 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

4. When the first partial dispersion ratio of the material forming the plurality of positive lenses is θsp, 1.75 ≤ θsp ≤ 2.38 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

5. The aforementioned rear lens group includes a plurality of pairs of negative lenses included in the plurality of negative lenses and positive lenses positioned next to the negative lenses, When the Abbe number of the material forming the plurality of negative lenses is νn, the Abbe number of the material forming the plurality of positive lenses is νp, and the first partial dispersion ratio is θsp, 2.7×10 －３ ≦(θ-θ-) / (ν-ν-) The zoom lens according to claim 1, characterized in that it satisfies the following condition.

6. When νna is the average value of the Abbe number νn of all materials forming negative lenses in the rear lens group, θsna is the average value of the first partial dispersion ratio of all materials forming negative lenses in the rear lens group, νpa is the average value of the Abbe number νp of all materials forming positive lenses in the rear lens group, and θspa is the average value of the first partial dispersion ratio of all materials forming positive lenses in the rear lens group, 0≦(θsna-θspa) / (νpa-νna)≦6.1×10 －２ The zoom lens according to claim 1, characterized in that it satisfies the following condition.

7. When the focal length of the rear lens group is fr and the focal length of the negative lens included in the plurality of negative lenses is fn, the plurality of negative lenses are -8.0 ≤ fr / fn ≤ -1.2 The zoom lens according to claim 1, characterized by including a negative lens that satisfies the following condition.

8. When the focal length of the rear lens group is fr, the focal length of the negative lens included in the plurality of negative lenses is fn, and the average value of fr / fn for the plurality of negative lenses is kna, -6.0 ≤ kna ≤ -1.0 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

9. A zoom lens comprising, in order from the object side to the image side, a first lens group with positive refractive power that does not move for zooming, a plurality of moving lens groups including at least one lens group with negative refractive power, and a rear lens group with positive refractive power that does not move for zooming, The spacing between adjacent lens groups changes for zooming purposes. When the focal length of the zoom lens at infinity focus and the wide-angle end is fw, the focal length of the zoom lens at infinity focus and the telephoto end is ft, the focal length of the first lens group is f1, and the maximum aperture F-number of the zoom lens at the wide-angle end is Fnw, 3.5 ≤ ft / f1 ≤ 6.0 4.7 ≤ fw / Fnw ≤ 12.0 The following conditions are met: When the refractive indices of the materials for wavelengths of C, F, and 1970 nm are NC, NF, and N1970, respectively, the first partial dispersion ratio θs is: θs=(NC-N1970) / (NF-NC) Defined by, The aforementioned rear lens group, when the refractive index with respect to the d line is Ndn and the first partial dispersion ratio is θsn, 1.55 ≤ Ndn ≤ 1.75 2.10 ≤ θsn ≤ 2.60 It includes multiple negative lenses formed from materials that satisfy the following condition: The aforementioned rear lens group includes a plurality of pairs of negative lenses included in the plurality of negative lenses and positive lenses positioned next to the negative lenses, When the Abbe number of the material forming the plurality of negative lenses is νn, the Abbe number of the material forming the plurality of positive lenses is νp, and the first partial dispersion ratio is θsp, 2.7×10 −3 ≦(θsn−θsp) / (νp−νn) A zoom lens characterized by satisfying the following condition.

10. A zoom lens comprising, in order from the object side to the image side, a first lens group with positive refractive power that does not move for zooming, a plurality of moving lens groups including at least one lens group with negative refractive power, and a rear lens group with positive refractive power that does not move for zooming, The spacing between adjacent lens groups changes for zooming purposes. When the focal length of the zoom lens at infinity focus and the wide-angle end is fw, the focal length of the zoom lens at infinity focus and the telephoto end is ft, the focal length of the first lens group is f1, and the maximum aperture F-number of the zoom lens at the wide-angle end is Fnw, 3.5 ≤ ft / f1 ≤ 6.0 4.7 ≤ fw / Fnw ≤ 12.0 The following conditions are met: When the refractive indices of the materials for wavelengths of C, F, and 1970 nm are NC, NF, and N1970, respectively, the first partial dispersion ratio θs is: θs=(NC-N1970) / (NF-NC) Defined by, The aforementioned rear lens group, when the refractive index with respect to the d line is Ndn and the first partial dispersion ratio is θsn, 1.55 ≤ Ndn ≤ 1.75 2.10 ≤ θsn ≤ 2.60 It includes multiple negative lenses formed from materials that satisfy the following condition: When νna is the average value of the Abbe number νn of all materials forming negative lenses in the rear lens group, θsna is the average value of the first partial dispersion ratio of all materials forming negative lenses in the rear lens group, νpa is the average value of the Abbe number νp of all materials forming positive lenses in the rear lens group, and θspa is the average value of the first partial dispersion ratio of all materials forming positive lenses in the rear lens group, 0≦(θsna−θspa) / (νpa−νna)≦6.1×10 −2 A zoom lens characterized by satisfying the following condition.

11. An imaging device characterized by having a zoom lens according to any one of claims 1 to 10 and an image sensor for capturing an image formed by the zoom lens.

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