Zoom lens and imaging device having the same

Abstract

To provide a zoom lens with a wide angle of view, high zoom ratio, compact and lightweight design, and high optical performance across the entire zoom range. [Solution] The zoom lens has a front group with positive refractive power, which includes at least one lens group arranged sequentially from the object side to the image side; a second lens group with negative refractive power that moves during zooming; a third lens group with positive refractive power that moves during zooming; a fourth lens group with positive refractive power that moves during zooming; and a fifth lens group that remains stationary during zooming, wherein the spacing between adjacent lens groups changes during zooming.

Description

Technical Field

[0001] The present disclosure relates to a zoom lens and an imaging device having the same.

Background Art

[0002] Conventionally, as a wide-angle and high-zoom-ratio zoom lens, a positive-lead type zoom lens having a first lens group with positive refractive power and a second lens group with negative refractive power for zooming, which are arranged in order from the object side to the image side, is known.

Summary of the Invention

Problems to be Solved by the Invention

[0003] There is a demand for a zoom lens that has a wider angle of view, a higher zoom ratio, is smaller and lighter, and has high optical performance over the entire zoom range than conventional ones.

Means for Solving the Problems

[0004] A zoom lens according to one aspect of the present disclosure includes a front group with positive refractive power including at least one or more lens groups, which are arranged in order from the object side to the image side, a second lens group with negative refractive power that moves during zooming, a third lens group with positive refractive power that moves during zooming, a fourth lens group with positive refractive power that moves during zooming, and a fifth lens group that is stationary during zooming, and is a zoom lens in which the interval between adjacent lens groups changes during zooming, and the aperture stop is arranged between the fourth lens group and the fifth lens group or within the fifth lens group, the front group consists of a total of 5 to 8 lenses, the lens group that is stationary during zooming is arranged on the most object side of the front group, when the focal length at the wide-angle end of the front group is f1, the focal length of the second lens group is f2, the air-equivalent length of the distance on the optical axis from the most object-side lens surface to the image surface is L, and the air-equivalent length of the distance on the optical axis from the aperture stop to the image surface is Lr, -9.2 < f1 / f2 < -5.5 0.20 < f1 / L < 0.35 0.9 < f1 / Lr < 2.0 It is characterized by satisfying the following conditional expression.

[0005] Furthermore, another aspect of this disclosure, a zoom lens, comprises a front group with positive refractive power including at least one lens group arranged sequentially from the object side to the image side, a second lens group with negative refractive power that moves during zooming, a third lens group with positive refractive power that moves during zooming, a fourth lens group with positive refractive power that moves during zooming, and a fifth lens group that remains stationary during zooming, characterized in that the spacing between adjacent lens groups changes during zooming. [Brief explanation of the drawing]

[0006] [Figure 1] This is a cross-sectional view of the zoom lens in Example 1 when it is in focus on an object at infinity at the wide-angle end. [Figure 2] These are longitudinal aberration diagrams of the zoom lens of Example 1 at infinity focus (a) wide-angle end, (b) f=50.5mm, and (c) telephoto end. [Figure 3] This is a cross-sectional view of the zoom lens in Example 2 when it is in focus on an object at infinity at the wide-angle end. [Figure 4] These are longitudinal aberration diagrams of the zoom lens of Example 2 at infinity focus (a) wide-angle end, (b) f=46.9mm, and (c) telephoto end. [Figure 5] This is a cross-sectional view of the zoom lens in Example 3 when it is in focus on an object at infinity at the wide-angle end. [Figure 6] These are longitudinal aberration diagrams of the zoom lens of Example 3 at infinity focus (a) wide-angle end, (b) f=40.7mm, and (c) telephoto end. [Figure 7] This is a cross-sectional view of the zoom lens in Example 4 when it is in focus on an object at infinity at the wide-angle end. [Figure 8] These are longitudinal aberration diagrams of the zoom lens of Example 4 at infinity focus (a) wide-angle end, (b) f=42.4mm, and (c) telephoto end. [Figure 9] This is a cross-sectional view of the zoom lens in Example 5 when it is in focus on an object at infinity at the wide-angle end. [Figure 10]These are longitudinal aberration diagrams of the zoom lens of Example 5 at infinity focus: (a) wide-angle end, (b) f=47.7mm, and (c) telephoto end. [Figure 11] This is a schematic diagram of the main components of the imaging device. [Modes for carrying out the invention]

[0007] The embodiments of this disclosure will be described in detail below with reference to the drawings. In each drawing, the same reference numeral is used for identical components, and redundant descriptions are omitted.

[0008] Figures 1, 3, 5, 7, and 9 are cross-sectional views of the zoom lenses of Examples 1 to 5 when focused on an object at infinity at the wide-angle end. The zoom lenses of each example are used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, surveillance cameras, and in-vehicle cameras.

[0009] In each cross-sectional view, the left side is the object side and the right side is the image side. Note that the zoom lens in each embodiment may also be used as a projection lens for a projector or the like. In this case, the left side is the screen side and the right side is the projected image side.

[0010] Each embodiment of the zoom lens is composed of multiple lens groups. In this specification, a lens group is a collection of lenses that move or remain stationary as a whole during zooming (magnification). That is, in each embodiment of the zoom lens, the distance between adjacent lens groups changes during zooming. A lens group may consist of a single lens or multiple lenses. Furthermore, a lens group may include an aperture diaphragm.

[0011] In each cross-sectional view, Li represents the i-th lens group (where i is a natural number) from the object side among the lens groups included in the zoom lens.

[0012] Also, the SP is an aperture stop. I is the image plane. When the zoom lens of each embodiment is used as the imaging optical system of a digital still camera or a digital video camera, the imaging surface of an imaging device (photoelectric conversion element) such as a CCD sensor or a CMOS sensor is disposed at the image plane. When the zoom lens of each embodiment is used as the imaging optical system of a camera for silver halide film, a photosensitive surface corresponding to the film surface is placed at the image plane I. P is a glass block such as a faceplate of a CCD sensor, a low-pass filter, or a color separation prism.

[0013] Also, the solid-line arrows indicate the movement trajectories of the respective lens groups during zooming from the wide-angle end (short focal length end) to the telephoto end (long focal length end). Further, when focusing from infinity to the nearest subject, the lens group (focus group) moves as indicated by the arrow marked FOCUS.

[0014] FIG. 2, FIG. 4, FIG. 6, FIG. 8, and FIG. 10 are longitudinal aberration diagrams of the zoom lenses of Embodiments 1 to 5, respectively, at an object distance of infinity. In each aberration diagram, (a) is the longitudinal aberration diagram at the wide-angle end, (b) is the aberration diagram at the intermediate zoom position, and (c) is the aberration diagram at the telephoto end. The focal lengths at the intermediate zoom positions of Embodiments 1 to 5 are 50.5 mm, 46.9 mm, 40.7 mm, 42.4 mm, and 47.7 mm, respectively.

[0015] In the spherical aberration diagram, Fno is the F-number, and it shows the amount of spherical aberration with respect to the e-line (wavelength 546.1 nm) and the g-line (wavelength 435.8 nm). In the astigmatism diagram, S shows the amount of astigmatism at the sagittal image plane of the e-line, and M shows the amount of astigmatism at the meridional image plane of the e-line. The distortion aberration diagram shows the amount of distortion aberration with respect to the e-line. The chromatic aberration diagram shows the amount of chromatic aberration at the g-line. ω is the semi-aperture angle [°].

[0016] Hereinafter, the characteristic configurations of the zoom lenses of the respective embodiments will be described.

[0017] The zoom lens of each embodiment includes a front group L1 with a positive refractive power, a second lens group L2 with a negative refractive power, a third lens group L3 with a positive refractive power, a fourth lens group L4 with a positive refractive power, and a fifth lens group L5, which are arranged in order from the object side to the image side. The second lens group L2, the third lens group L3, and the fourth lens group L4 move during zooming. Also, the fifth lens group L5 is stationary during zooming. Further, the aperture stop SP is arranged between the fourth lens group L4 and the fifth lens group L5 or within the fifth lens group L5.

[0018] With such a configuration, the zoom lens of each embodiment is advantageous for achieving a high magnification.

[0019] Hereinafter, in the zoom lens of each embodiment, a preferable configuration that is satisfied will be described.

[0020] The front group L1 preferably consists of a total of 5 to 8 lenses.

[0021] It is preferable that a lens group that is stationary during zooming is arranged on the object side of the front group L1 closest to the object side.

[0022] The front group L1 preferably has a lens group that moves toward the object side during focusing from infinity to the closest distance. This is preferable because the number of lenses in the front group L1 can be reduced and miniaturization of the zoom lens can be achieved.

[0023] Hereinafter, preferable conditions that the zoom lens of each embodiment satisfies will be described. The zoom lens of each embodiment preferably satisfies one or more of the following conditional expressions (1) to (11).

[0024] -9.2 < f1 / f2 < -5.5 ···(1) 0.20 < f1 / L < 0.35 ···(2) 0.9 < f1 / Lr < 2.0 ···(3) -0.4 < f2 / f34 < -0.2 ···(4) <0000111.40 <ndl<1.65 ···(5) 2.0 < (β2t / β2w) 2 ×(fw / ft)<5.0 ···(6) 0.8 < |m² / m³| < 2.5 ···(7) -4.0 <fg1 / f1<-1.0 ···(8) 1.80 <ndg1<1.95 ···(9) 1.5 <ft / f1<4.0 ···(10) 15 <f1 / fw<30 ···(11) Here, f1 is the focal length of the front lens group L1 at its wide-angle end. f2 is the focal length of the second lens group L2. L is the air-equivalent length (total length of the zoom lens) of the distance along the optical axis from the lens surface closest to the object to the image plane. Lr is the air-equivalent length of the distance along the optical axis from the aperture diaphragm SP to the image plane. f34 is the combined focal length of the third lens group L3 and the fourth lens group L4. nd1 is the refractive index of the lens closest to the image in the front lens group L1. β2w and β2t are the lateral magnification of the second lens group L2 at its wide-angle and telephoto ends, respectively. fw and ft are the focal lengths at the wide-angle and telephoto ends of the zoom lens, respectively. m2 and m3 are the difference in the positions of the second lens group L2 and the third lens group on the optical axis at the wide-angle end and the telephoto end, respectively (the distance on the optical axis from the lens surface closest to the image of the second lens group L2 to the lens surface closest to the object of the third lens group L3). fg1 and ndg1 are the focal length and refractive index of the lens closest to the object of the front lens group L1, respectively.

[0025] Conditional equation (1) specifies the ratio of the focal lengths of the front lens group L1 and the second lens group L2 in order to achieve both a wide angle of view and high optical performance in a zoom lens. If the ratio exceeds the upper limit of conditional equation (1), the refractive power of the front lens group L1 becomes strong, making it difficult to correct aberrations at the telephoto end and making it difficult to achieve high optical performance. If the ratio falls below the lower limit of conditional equation (1), the refractive power of the front lens group L1 becomes weak, making it difficult to achieve both a wide angle of view and miniaturization.

[0026] Condition (2) specifies the ratio of the focal length of the front group L1 to the total length of the zoom lens in order to achieve both a wide angle of view and a compact size for the zoom lens. If the ratio exceeds the upper limit of condition (2), the refractive power of the front group L1 weakens, making it difficult to widen the angle of view of the zoom lens. If the ratio falls below the lower limit of condition (2), the total length of the zoom lens increases, making it difficult to miniaturize.

[0027] Conditional equation (3) specifies the ratio of the focal length of the front lens group L1 to the distance from the aperture diaphragm SP to the image plane in order to achieve both a wide angle of view and a compact size for the zoom lens. If the ratio exceeds the upper limit of conditional equation (3), the refractive power of the front lens group L1 weakens, making it difficult to widen the angle of view of the zoom lens. If the ratio falls below the lower limit of conditional equation (3), the lens thickness of the fifth lens group L5 (the distance along the optical axis from the lens surface closest to the object to the lens surface closest to the image) becomes longer, making it difficult to miniaturize the zoom lens.

[0028] Condition (4) is defined to achieve both miniaturization and high optical performance in zoom lenses. If the upper limit of condition (4) is exceeded, the refractive power of the second lens group L2 becomes stronger, making it difficult to correct distortion at the wide-angle end and spherical aberration in the middle of the zoom range, thus making it difficult to achieve high optical performance. If the lower limit of condition (4) is exceeded, the refractive power of the second lens group L2 becomes weaker, increasing the amount of movement of the second lens group L2 and the third lens group L3 during zooming, making it difficult to miniaturize the zoom lens.

[0029] Conditional equation (5) is defined to achieve both correction of axial chromatic aberration at the telephoto end and correction of distortion at the mid-zoom range. If the upper limit of conditional equation (5) is exceeded, the Abbe number of the lens in question becomes small, making it difficult to correct axial chromatic aberration at the telephoto end, especially the second-order spectrum. If the lower limit of conditional equation (5) is exceeded, the refractive index of the lens in question becomes small, making it difficult to correct the pincushion distortion that occurs at the mid-zoom range.

[0030] Condition (6) defines the ratio of the lateral magnification (magnification contribution) of the second lens group L2 at its wide-angle and telephoto ends to the ratio of the magnification contribution of the other lens groups. By satisfying condition (6), it is possible to achieve high magnification while simultaneously miniaturizing the zoom lens and correcting axial chromatic aberration. If the upper limit of condition (6) is exceeded, the lateral magnification of the second lens group L2 at its telephoto end increases, and the axial chromatic aberration occurring in the second lens group L2 increases. Therefore, it becomes difficult to adequately correct the optical performance at the telephoto end, especially axial chromatic aberration. If the lower limit of condition (6) is exceeded, the magnification contribution of the second lens group L2 decreases, so the amount of movement of the lens groups other than the second lens group L2 increases, making it difficult to achieve both high magnification and miniaturization of the zoom lens.

[0031] Condition (7) is defined to achieve both high magnification and miniaturization of the zoom lens while correcting axial chromatic aberration. If the upper limit of condition (7) is exceeded, the amount of movement of the second lens group L2 increases, which increases the lateral magnification of the second lens group L2 at the telephoto end and increases the axial chromatic aberration occurring in the second lens group L2. As a result, it becomes difficult to adequately correct the optical performance at the telephoto end, especially axial chromatic aberration. If the lower limit of condition (7) is exceeded, the amount of movement of the second lens group L2 decreases, which increases the sum of the movement amounts of the second lens group L2 and the third lens group L3, making it difficult to miniaturize the zoom lens.

[0032] Conditional equations (8) and (9) are defined to achieve wider angle of view, higher magnification, and smaller size for zoom lenses. If the upper limit of conditional equation (8) is exceeded, the refractive power of the lens closest to the object in the front group L1 becomes stronger than the refractive power of the front group L1, increasing higher-order aberrations of spherical aberration at the telephoto end and making it difficult to achieve good optical performance. If the lower limit of conditional equation (8) is exceeded, the refractive power of the lens closest to the object in the front group L1 becomes weaker than the refractive power of the front group L1, increasing the diameter of the lens and making it difficult to miniaturize the zoom lens. If the upper limit of conditional equation (9) is exceeded, the Abbe number of the lens closest to the object in the front group L1 becomes smaller, making it difficult to correct axial chromatic aberration, especially the second-order spectrum, at the telephoto end. If the lower limit of conditional equation (9) is exceeded, it becomes difficult to miniaturize the zoom lens.

[0033] Conditional equation (10) is defined to achieve both high magnification and miniaturization of the zoom lens while correcting axial chromatic aberration. Exceeding the upper limit of conditional equation (10) is advantageous for miniaturizing the zoom lens, but the magnification of aberrations occurring in the front group L1 increases, making it difficult to properly correct the optical performance at the telephoto end, especially axial chromatic aberration. Exceeding the lower limit of conditional equation (10) weakens the refractive power of the front group L1, making it difficult to achieve both a wide angle of view and miniaturization of the zoom lens.

[0034] Condition (11) is defined to achieve both miniaturization of the zoom lens and good peripheral performance at the wide-angle end. If the upper limit of condition (11) is exceeded, the refractive power of the front group L1 weakens, making it difficult to achieve both high magnification and miniaturization of the zoom lens. If the lower limit of condition (11) is exceeded, the refractive power of the front group L1 strengthens, making it difficult to correct field curvature and distortion at the wide-angle end.

[0035] Furthermore, it is more preferable that the lower limit of conditional expression (1) be set to -9.19, -9.18, -9.17, -9.16, -9.15, -9.14, -9.13, -9.12, -9.11, or -9.10. It is more preferable that the upper limit of conditional expression (1) be set to -5.510, -5.515, -5.520, -5.525, -5.530, -5.535, -5.540, -5.545, -5.548, or -5.550.

[0036] Furthermore, it is more preferable that the lower limit of condition (2) be set to 0.205, 0.210, 0.215, 0.220, 0.225, 0.230, 0.235, 0.240, 0.245, or 0.250. It is more preferable that the upper limit of condition (2) be set to 0.349, 0.348, 0.347, or 0.346.

[0037] Furthermore, it is more preferable that the lower limit of condition (3) be set to 0.91, 0.92, 0.93, 0.94, 0.95, or 0.96. It is more preferable that the upper limit of condition (3) be set to 1.90, 1.80, 1.70, 1.60, 1.50, 1.40, or 1.30.

[0038] Furthermore, it is more preferable that the lower limit of conditional expression (4) be set to -0.39, -0.38, -0.37, -0.36, -0.35, or -0.34. It is more preferable that the upper limit of conditional expression (4) be set to -0.21, -0.22, -0.23, -0.24, -0.25, -0.26, -0.27, or -0.28.

[0039] Furthermore, it is more preferable that the lower limit of conditional expression (5) be set to 1.41, 1.42, 1.43, 1.44, 1.45, 1.46, 1.47, 1.48, 1.49, or 1.50. It is more preferable that the upper limit of conditional expression (5) be set to 1.645, 1.640, 1.635, 1.630, 1.625, or 1.620.

[0040] Furthermore, it is more preferable that the lower limit of conditional expression (6) be set to 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, or 2.7. It is more preferable that the upper limit of conditional expression (6) be set to 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, or 4.2.

[0041] Furthermore, it is more preferable that the lower limit of conditional expression (7) be set to 0.82, 0.84, 0.86, 0.88, 0.90, 0.92, 0.94, 0.96, 0.98, or 1.00. It is more preferable that the upper limit of conditional expression (7) be set to 2.45, 2.40, 2.35, 2.30, 2.25, 2.20, 2.15, 2.10, 2.05, or 2.00.

[0042] Furthermore, it is more preferable that the lower limit of conditional expression (8) be set to -3.9, -3.8, -3.7, -3.6, -3.5, -3.4, -3.3, -3.2, -3.1, or -3.0. It is more preferable that the upper limit of conditional expression (8) be set to -1.05, -1.10, -1.15, -1.20, -1.25, -1.30, -1.35, or -1.40.

[0043] Furthermore, it is more preferable that the lower limit of condition expression (9) be set to 1.801, 1.802, 1.803, 1.804, 1.805, 1.806, 1.807, or 1.808. It is more preferable that the upper limit of condition expression (9) be set to 1.899, 1.898, 1.897, 1.896, 1.895, 1.894, 1.893, or 1.892.

[0044] Furthermore, it is more preferable that the lower limit of condition expression (10) be set to 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, or 1.90. It is more preferable that the upper limit of condition expression (10) be set to 3.8, 3.6, 3.4, 3.2, 3.0, or 2.8.

[0045] Furthermore, it is more preferable that the lower limit of condition expression (11) be set to 15.5, 16.0, 16.5, 17.0, 17.5, 18.0, 18.5, 19.0, 19.5, or 20.0. It is more preferable that the upper limit of condition expression (11) be set to 29.5, 29.0, 28.5, 28.0, 27.5, 27.0, or 26.5.

[0046] Next, we will describe the zoom lenses of each embodiment in detail.

[0047] The zoom lens of Example 1 has a front lens group L1 and second to fifth lens groups L2 to L5 arranged sequentially from the object side to the image side. The front lens group L1 consists of six lenses. The front lens group L1 also includes lens groups L11 and L12. Lens group L11 is stationary during zooming. Lens group L12 moves during zooming and also moves towards the object side when focusing from infinity to the near side. The second lens group L2 moves towards the image side when zooming from the wide-angle end to the telephoto end. The third lens group L3 moves along a convex trajectory toward the object side during zooming. The fourth lens group L4 moves nonlinearly along the optical axis in conjunction with the movement of the second lens group L2 and the third lens group L3, correcting image plane fluctuations associated with zooming. The second lens group L2, the third lens group L3, and the fourth lens group L4 constitute a variable magnification system. The aperture diaphragm SP is located between the fourth lens group L4 and the fifth lens group L5. Furthermore, the aperture diaphragm SP remains stationary during zooming.

[0048] The zoom lens of Example 2 has a front lens group L1 and second to fifth lens groups L2 to L5 arranged sequentially from the object side to the image side. The front lens group L1 consists of six lenses. The front lens group L1 also includes lens groups L11 and L12. Lens group L11 remains stationary during zooming. Lens group L12 moves towards the object side when focusing from infinity to the near side. The second lens group L2 moves towards the image side when zooming from the wide-angle end to the telephoto end. The third lens group L3 moves along a convex trajectory toward the object side during zooming. The fourth lens group L4 moves nonlinearly along the optical axis in conjunction with the movement of the second lens group L2 and the third lens group L3, correcting image plane fluctuations associated with zooming. Lens group L12, the second lens group L2, the third lens group L3, and the fourth lens group L4 constitute a variable magnification system. The aperture diaphragm SP is located between the fourth lens group L4 and the fifth lens group L5. Furthermore, the aperture diaphragm SP remains stationary during zooming.

[0049] The zoom lens of Example 3 has a front lens group L1 and second to fifth lens groups L2 to L5 arranged sequentially from the object side to the image side. The front lens group L1 consists of six lenses. The front lens group L1 also includes lens groups L11 and L12. Lens group L11 remains stationary during zooming. Lens group L12 moves towards the object side when focusing from infinity to the near side. The second lens group L2 moves towards the image side when zooming from the wide-angle end to the telephoto end. The third lens group L3 moves along a convex trajectory toward the object side during zooming. The fourth lens group L4 moves nonlinearly along the optical axis in conjunction with the movement of the second lens group L2 and the third lens group L3, correcting image plane fluctuations associated with zooming. The second lens group L2, the third lens group L3, and the fourth lens group L4 constitute a variable magnification system. The aperture diaphragm SP is located between the fourth lens group L4 and the fifth lens group L5. Furthermore, the aperture diaphragm SP remains stationary during zooming.

[0050] The zoom lens of Example 4 has a front lens group L1 and second to fifth lens groups L2 to L5 arranged sequentially from the object side to the image side. The front lens group L1 consists of seven lenses. The front lens group L1 also includes lens groups L11 and L12. Lens group L11 remains stationary during zooming. Lens group L12 moves towards the object side when focusing from infinity to the near side. The second lens group L2 moves towards the image side when zooming from the wide-angle end to the telephoto end. The third lens group L3 moves along a convex trajectory toward the object side during zooming. The fourth lens group L4 moves nonlinearly along the optical axis in conjunction with the movement of the second lens group L2 and the third lens group L3, correcting image plane fluctuations associated with zooming. The second lens group L2, the third lens group L3, and the fourth lens group L4 constitute a variable magnification system. The aperture diaphragm SP is located between the fourth lens group L4 and the fifth lens group L5. Furthermore, the aperture diaphragm SP remains stationary during zooming.

[0051] The zoom lens of Example 5 has a front lens group L1 and second to fifth lens groups L2 to L5 arranged in order from the object side to the image side. The front lens group L1 consists of eight lenses. The front lens group L1 also includes lens groups L11, L12, and L13. Lens group L11 is stationary during zooming. Lens groups L12 and L13 move during zooming and also move towards the object side when focusing from infinity to the near side. The second lens group L2 moves towards the image side when zooming from the wide-angle end to the telephoto end. The third lens group L3 moves along a convex trajectory toward the object side during zooming. The fourth lens group L4 moves nonlinearly along the optical axis in conjunction with the movement of the second lens group L2 and the third lens group L3, correcting image plane fluctuations associated with zooming. The lens group L12, L13, the second lens group L2, the third lens group L3, and the fourth lens group L4 constitute the variable magnification system. The aperture diaphragm SP is positioned between the fourth lens group L4 and the fifth lens group L5. Furthermore, the aperture diaphragm SP remains stationary during zooming.

[0052] The numerical values ​​corresponding to Examples 1 to 5 are shown below.

[0053] In the surface data for each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the on-axial spacing (distance along the optical axis) between the m-th surface and the (m+1)-th surface. Here, m is the surface number counted from the light incidence side. Furthermore, nd represents the refractive index of each optical element with respect to the d-line, and νd represents the Abbe number of each optical element with respect to the d-line. Note that the Abbe number νd of a certain material is given by Nd, NF, and NC, respectively, when the refractive indices at the Fraunhofer lines d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) are Nd, NF, and NC. νd = (Nd-1) / (NF-NC) It is represented as follows.

[0054] In each numerical example, d, focal length (mm), F-number, and half-angle of view [°] are all values ​​when the zoom lens of each example is focused on an object at infinity. The half-angle of view is a value obtained by ray tracing. "Lens length" is expressed as the distance along the optical axis from the lens surface closest to the object among the optically powerful lens surfaces to the paraxial image plane, expressed as the air-equivalent length (length excluding optical block G). "BF" is the back focus, expressed as the distance along the optical axis from the lens surface closest to the image among the optically powerful lens surfaces to the paraxial image plane, expressed as the air-equivalent length.

[0055] Furthermore, if the optical surface is aspherical, the sign * is added to the right of the surface number. The aspherical shape is defined as follows, where X is the displacement from the surface vertex in the optical axis direction, H is the height from the optical axis perpendicular to the optical axis, R is the radius of paraxial curvature, k is the cone constant, and A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16 are the aspherical coefficients of their respective orders.

[0056]

number

[0057] This is expressed as follows. Note that "e±XX" in each aspherical coefficient is "×10± XX It means "...".

[0058] Furthermore, in the "Zoom Lens Group Data," in numerical example 2, groups 1 to 6 refer to lens groups L11, L12, the second lens group L2, the third lens group L3, the fourth lens group L4, and the fifth lens group L5, respectively. Also, in numerical example 2, groups 1 to 7 refer to lens groups L11, L12, L13, the second lens group L2, the third lens group L3, the fourth lens group L4, and the fifth lens group L5, respectively.

[0059] [Numerical Example 1] Unit: mm Surface data Face number rd nd νd Effective diameter 1 2014.609 3.50 1.85150 40.8 187.01 2 199.631 1.29 170.69 3 197.744 22.68 1.43387 95.1 169.82 4 -3508.269 0.21 167.91 5 314.583 11.13 1.43387 95.1 154.72 6 2917.909 13.05 152.31 7 289.493 10.46 1.43387 95.1 132.63 8 -8223.779 0.21 132.34 9 232.005 11.89 1.43387 95.1 130.67 10 ∞ 2.36 129.93 11 144.777 10.52 1.59522 67.7 123.05 12 308.254 (variable) 121.33 13* 651.386 1.84 2.00330 28.3 48.45 14 27.363 16.09 37.63 15 -28.647 1.21 1.71999 50.2 35.35 16 124.441 7.89 1.92286 18.9 37.51 17 -49.039 5.56 38.00 18 -36.188 1.67 1.88300 40.8 35.91 19 -52.198 (variable) 36.86 20 107.821 7.12 1.76385 48.5 53.93 21* 1544.136 8.04 54.06 22 1007.660 8.63 1.43875 94.7 55.23 23 -83.495 0.41 55.53 24 -4364.139 2.17 1.85478 24.8 54.57 25 169.797 (Variable) 54.15 26 92.137 9.57 1.49700 81.5 55.21 27 -135.558 2.34 1.84666 23.8 54.86 28 -552.716 0.17 54.71 29* 207.128 7.26 1.59522 67.7 54.37 30 -112.099 (variable) 53.99 31 (aperture) ∞ 3.00 31.21 32 -179.056 1.40 1.88300 40.8 29.84 33 32.115 1.44 28.68 34 31.627 5.21 1.89286 20.4 29.59 35 118.008 6.16 28.99 36 -29.791 1.50 1.80400 46.5 28.59 37 -33.222 5.08 29.20 38 -279.536 1.50 1.89190 37.1 27.75 39 32.019 4.70 1.78880 28.4 27.59 40 218.135 3.75 27.63 41 -54.680 1.50 1.88300 40.8 27.84 42 173.800 12.23 1.51742 52.4 29.09 43 -28.921 10.40 32.09 44 66.028 4.87 1.53172 48.8 32.31 45 -152.244 1.40 31.98 46 -79.077 1.50 1.89190 37.1 31.74 47 41.961 8.03 1.49700 81.5 31.96 48 -63.845 0.20 32.96 49 57.210 8.28 1.51633 64.1 34.39 50 -48.812 1.50 1.88300 40.8 34.31 51 -229.997 0.20 34.79 52 106.162 6.08 1.54814 45.8 35.00 53 -61.944 10.00 34.88 54 ∞ 33.00 1.60859 46.4 60.00 55 ∞ 13.20 1.51633 64.2 60.00 56 ∞ 13.29 60.00 Image plane ∞ Aspherical data Page 13 K = 1.88057e+00 A 4= 3.75993e-06 A 6=-3.52239e-09 A 8= 7.00174e-12 A10=-1.33305e-14 A12= 9.86321e-18 A14= 5.09933e-21 A16=-6.70836e-24 Page 21 K =-1.22863e+04 A 4= 8.91773e-07 A 6=-6.96741e-10 A 8= 1.10623e-12 A10=-9.52760e-16 A12= 3.45567e-19 Page 29 K =-1.31121e+02 A 4= 1.09392e-06 A 6=-2.32209e-09 A 8= 2.76762e-12 A10=-2.09067e-15 A12= 7.17988e-19 Various data Zoom ratio 60.00 Wide-angle, Medium, Telephoto Focal length 6.84 50.47 410.17 F-number 1.76 1.76 3.21 Half-angle [°] 38.82 6.22 0.77 Image height 5.50 5.50 5.50 Lens length 541.39 541.39 541.39 BF 13.29 13.29 13.29 d12 3.47 99.98 137.51 d19 207.41 76.06 4.00 d25 1.38 12.57 20.96 d30 2.45 26.11 52.25 Entrance pupil position 96.77 555.38 4109.64 Exit pupil position 181.88 181.88 181.88 Front principal point position 103.88 620.96 5517.72 Back principal point position 6.45 -37.18 -396.88 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 180.56 87.32 51.60 -10.55 2 13 -19.87 34.25 3.55 -23.66 3 20 140.45 26.38 -0.60 -20.00 4 26 82.79 19.34 6.89 -5.91 5 31 41.50 146.10 54.96 12.36 [Numerical Example 2] Unit: mm Surface data Face number rd nd νd Effective diameter 1 -4415.863 4.00 1.85150 40.8 185.00 2 216.944 1.51 169.04 3 217.109 23.89 1.43387 95.1 168.21 4 -799.803 0.21 166.44 5 333.827 12.21 1.43387 95.1 150.54 6 -2542.190 (variable) 148.11 7 269.078 11.15 1.43387 95.1 131.99 8 -5031.647 0.21 131.66 9 204.595 11.83 1.43387 95.1 129.42 10 1781.304 1.60 128.57 11 153.491 9.55 1.59522 67.7 122.08 12 334.887 (Variable) 120.62 13* -455.048 1.84 2.00330 28.3 50.03 14 29.454 15.68 39.20 15 -32.142 1.21 1.71999 50.2 37.63 16 116.008 8.78 1.92286 18.9 39.88 17 -48.317 5.41 40.36 18 -37.856 1.67 1.88300 40.8 37.70 19 -60.186 (variable) 38.65 20 98.119 7.71 1.76385 48.5 56.28 21* 1517.336 8.01 56.20 22 988.260 8.56 1.43875 94.7 56.77 23 -89.280 0.41 56.89 24 495.806 2.17 1.85478 24.8 55.40 25 116.397 (Variable) 54.52 26 114.332 7.56 1.49700 81.5 55.09 27 -225.587 2.34 1.84666 23.8 54.78 28 2305.585 0.17 54.56 29* 186.826 6.95 1.59522 67.7 54.43 30 -140.233 (variable) 54.08 31 (aperture) ∞ 3.00 30.72 32 -184.527 1.40 1.88300 40.8 29.58 33 36.123 1.35 28.75 34 34.659 4.35 1.89286 20.4 29.57 35 143.936 6.28 29.20 36 -38.937 1.50 1.80400 46.5 28.60 37 -49.407 7.40 29.08 38 -711.226 1.50 1.89190 37.1 28.42 39 35.307 4.68 1.78880 28.4 28.34 40 163.410 8.15 28.42 41 -95.624 1.50 1.88300 40.8 29.67 42 170.125 7.76 1.51742 52.4 30.51 43 -34.067 10.48 31.66 44 64.253 4.56 1.53172 48.8 31.99 45 -237.619 1.40 31.65 46 -89.925 1.50 1.89190 37.1 31.48 47 39.553 8.15 1.49700 81.5 31.55 48 -63.040 0.20 32.58 49 65.896 8.10 1.51633 64.1 33.95 50 -44.456 1.50 1.88300 40.8 33.98 51 -178.266 0.20 34.65 52 113.261 6.39 1.54814 45.8 35.00 53 -53.637 10.00 34.96 54 ∞ 33.00 1.60859 46.4 60.00 55 ∞ 13.20 1.51633 64.2 60.00 56 ∞ 13.27 60.00 Image plane ∞ Aspherical data Page 13 K =-1.99999e+00 A 4= 3.80072e-06 A 6=-2.20511e-09 A 8= 8.83118e-13 A10=-4.40840e-15 A12= 1.49106e-17 A14=-1.96476e-20 A16= 9.37076e-24 Page 21 K =-1.02705e+04 A 4= 8.74044e-07 A 6=-5.10504e-10 A 8= 6.71945e-13 A10=-4.80538e-16 A12= 1.44450e-19 Page 29 K =-1.10170e+02 A 4= 1.67228e-06 A 6=-2.73625e-09 A 8= 3.34704e-12 A10=-2.61307e-15 A12= 9.14984e-19 Various data Zoom ratio 68.00 Wide-angle, Medium, Telephoto Focal length 6.75 46.92 459.00 F-number 1.76 1.76 3.64 Half-angle [°] 39.17 6.69 0.69 Image height 5.50 5.50 5.50 Lens length 550.84 550.84 550.84 BF 13.27 13.27 13.27 d 6 9.67 15.89 12.66 d12 3.34 90.23 129.67 d19 216.09 83.64 4.00 d25 3.32 10.81 15.67 d30 2.97 34.81 73.39 Entrance pupil position 93.41 484.58 4879.24 Exit pupil position 153.06 153.06 153.06 Front principal point position 100.49 547.24 6845.38 Back principal point position 6.52 -33.64 -445.73 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -43430.21 41.82 -1808.01 -1916.54 2 7 177.08 34.33 7.28 -16.53 3 13 -20.43 34.59 2.98 -24.19 4 20 138.13 26.87 -2.77 -22.03 5 26 104.03 17.01 5.86 -5.22 6 31 41.16 147.57 57.13 5.78 [Numerical Example 3] Unit: mm Surface data Face number rd nd νd Effective diameter 1 -713.603 4.00 1.89190 37.1 189.99 2 288.802 11.24 178.13 3 916.387 17.32 1.43387 95.1 177.62 4 -380.623 0.21 176.84 5 289.384 19.88 1.43387 95.1 161.63 6 -559.996 11.77 159.92 7 275.045 11.44 1.43387 95.1 139.54 8 42446.027 0.21 137.08 9 198.574 11.90 1.43387 95.1 121.82 10 11143.125 1.60 121.03 11 141.720 9.95 1.59522 67.7 114.86 12 352.808 (variable) 113.41 13* -341.337 1.84 2.00330 28.3 52.18 14 33.151 17.48 41.49 15 -29.230 1.21 1.71999 50.2 39.05 16 408.921 8.44 1.92286 18.9 42.26 17 -46.546 6.96 43.04 18 -32.248 1.67 1.88300 40.8 41.02 19 -38.314 (variable) 42.43 20 147.437 5.81 1.76385 48.5 46.61 21* 1514.699 8.01 46.92 22 -58.686 4.17 1.43875 94.7 47.41 23 -52.743 (variable) 48.66 24 209.087 9.61 1.49700 81.5 51.34 25 -108.071 2.34 1.84666 23.8 51.31 26 1786.938 0.17 51.81 27* 170.932 7.86 1.59522 67.7 52.16 28 -98.168 (variable) 52.21 29 (aperture) ∞ 3.00 28.39 30 -109.243 1.40 1.88300 40.8 27.74 31 41.896 1.34 27.57 32 39.609 5.56 1.80810 22.8 28.58 33 944.155 6.54 28.44 34 -28.921 1.50 1.80400 46.5 28.27 35 -32.033 6.58 29.04 36 107.559 1.50 1.89190 37.1 29.23 37 26.245 5.21 1.78880 28.4 28.65 38 98.625 9.31 28.54 39 -49.680 1.50 1.88300 40.8 29.36 40 -594.147 6.15 1.51742 52.4 30.63 41 -32.029 10.40 31.58 42 35.873 5.77 1.53172 48.8 36.25 43 144.013 1.40 35.79 44 390.654 1.50 1.89190 37.1 35.64 45 32.546 10.93 1.49700 81.5 34.65 46 -47.623 0.20 34.99 47 90.111 7.47 1.51633 64.1 33.94 48 -44.572 1.50 1.88300 40.8 33.25 49 -431.763 0.20 33.04 50 45.008 3.86 1.54814 45.8 32.47 51 104.456 10.00 31.71 52 ∞ 33.00 1.60859 46.4 60.00 53 ∞ 13.20 1.51633 64.2 60.00 54 ∞ 13.18 60.00 Image plane ∞ Aspherical data Page 13 K =-1.85237e+00 A 4= 3.99011e-06 A 6=-2.31100e-09 A 8= 2.03246e-12 A10=-4.96497e-15 A12= 1.49331e-17 A14=-2.01745e-20 A16= 1.06155e-23 Page 21 K = 2.53255e+03 A 4= 1.62854e-07 A 6=-4.27339e-11 A 8= 2.47394e-13 A10=-4.42717e-16 A12= 1.85371e-19 Page 27 K =-5.30121e+01 A 4= 8.92486e-07 A 6=-1.03676e-09 A 8= 9.65179e-13 A10=-6.05759e-16 A12= 1.84366e-19 Various data Zoom ratio 38.50 Wide-angle, Medium, Telephoto Focal length 6.99 40.66 269.28 F-number 2.00 2.00 2.43 Half-angle [°] 38.18 7.70 1.17 Image height 5.50 5.50 5.50 Lens length 551.79 551.79 551.79 BF 13.18 13.18 13.18 d12 3.37 80.74 110.83 d19 206.86 91.07 4.00 d23 1.81 9.26 13.28 d28 2.49 33.46 86.42 Entrance pupil position 98.55 416.76 2203.20 Exit pupil position 468.75 468.75 468.75 Front principal point position 105.65 461.06 2631.65 Back principal point position 6.18 -27.49 -256.10 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 147.54 99.51 66.26 1.07 2 13 -24.73 37.59 1.50 -31.30 3 20 179.73 17.99 6.13 -8.62 4 24 124.30 19.97 10.00 -3.03 5 29 52.79 149.03 59.37 -7.77 [Numerical Example 4] Unit: mm Surface data Face number rd nd νd Effective diameter 1 -613.271 3.50 1.83481 42.7 199.20 2 776.122 4.50 190.85 3 1716.670 3.50 1.89190 37.1 190.01 4 323.884 6.05 184.30 5 459.275 26.59 1.43387 95.1 183.85 6 -323.711 0.15 182.67 7 422.017 17.58 1.43387 95.1 166.83 8 -518.699 11.41 165.17 9 264.715 12.44 1.43387 95.1 143.10 10 -28539.051 0.15 140.64 11 178.075 12.97 1.43387 95.1 122.95 12 3974.250 1.60 122.09 13 130.787 10.93 1.53775 74.7 115.00 14 340.835 (variable) 113.45 15* -178.944 1.84 2.00330 28.3 51.37 16 32.666 17.62 40.94 17 -28.070 1.21 1.71999 50.2 39.33 18 -106.725 0.50 42.67 19 -220.586 8.31 1.92286 18.9 43.49 20 -39.534 4.61 44.41 21 -34.113 1.67 1.88300 40.8 41.67 22 -46.355 (variable) 43.12 23 154.733 3.97 1.76385 48.5 44.73 24* 2755.109 8.01 44.88 25 -53.564 3.97 1.43875 94.7 45.28 26 -49.633 (variable) 46.48 27 541.820 8.37 1.49700 81.5 48.44 28 -105.966 2.34 1.84666 23.8 48.59 29 -2121.282 0.17 49.16 30* 191.126 7.11 1.59522 67.7 49.50 31 -100.237 (variable) 49.58 32 (aperture) ∞ 3.00 28.16 33 -117.308 1.40 1.88300 40.8 27.60 34 40.288 1.45 27.50 35 39.645 5.60 1.80810 22.8 28.66 36 1311.627 6.43 28.60 37 -29.842 1.50 1.80400 46.5 28.56 38 -33.166 6.58 29.35 39 40.286 1.50 1.89190 37.1 30.17 40 26.759 0.20 29.17 41 27.271 4.66 1.78880 28.4 29.25 42 42.624 9.09 28.45 43 -54.786 1.50 1.88300 40.8 28.71 44 163.752 6.66 1.51742 52.4 29.87 45 -33.547 10.46 30.76 46 38.902 4.95 1.53172 48.8 35.21 47 123.845 1.66 34.85 48 2197.803 1.50 1.89190 37.1 34.78 49 37.778 10.23 1.49700 81.5 34.36 50 -45.341 0.20 34.83 51 75.506 7.82 1.51633 64.1 34.03 52 -44.574 1.50 1.88300 40.8 33.37 53 1675.849 0.20 33.19 54 54.730 4.73 1.54814 45.8 33.05 55 -1697.686 10.00 32.51 56 ∞ 33.00 1.60859 46.4 60.00 57 ∞ 13.20 1.51633 64.2 60.00 58 ∞ 13.20 60.00 Image plane ∞ Aspherical data Page 15 K =-1.49042e+00 A 4= 4.68023e-06 A 6=-2.70701e-09 A 8= 1.60063e-12 A10=-5.01758e-15 A12= 1.56994e-17 A14=-2.02273e-20 A16= 9.88254e-24 Page 24 K = 3.05916e+03 A 4= 1.99919e-07 A 6= 1.77207e-10 A 8=-3.14597e-13 A10=4.99623e-16 A12=-2.46872e-19 Page 30 K =-4.60147e+01 A 4= 4.35630e-07 A 6=-2.34493e-10 A 8=-3.57119e-13 A10=9.44416e-16 A12=-5.93445e-19 Various data Zoom ratio 38.48 Wide-angle, Medium, Telephoto Focal length 6.99 42.35 269.13 F-number 2.00 2.00 2.43 Half-angle [°] 38.18 7.40 1.17 Image height 5.50 5.50 5.50 Lens length 559.83 559.83 559.83 BF 13.20 13.20 13.20 d14 4.04 77.57 106.17 d22 203.58 89.93 2.75 d26 6.42 6.06 17.37 d31 2.49 42.97 90.23 Entrance pupil position 104.41 422.18 2366.16 Exit pupil position 401.63 401.63 401.63 Front principal point position 111.53 469.15 2821.75 Back principal point position 6.21 -29.15 -255.93 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 140.00 111.38 71.93 0.96 2 15 -25.00 35.75 0.38 -31.53 3 23 185.86 15.96 6.05 -7.44 4 27 142.57 17.98 10.59 -0.94 5 32 52.43 149.04 60.04 -12.48 [Numerical Example 5] Unit: mm Surface data Face number rd nd νd Effective diameter 1 4771.429 4.00 1.80400 46.5 197.78 2 922.789 0.70 191.46 3 689.008 10.00 1.43387 95.1 188.37 4 -5276.409 1.50 185.65 5 -5637.082 4.00 1.83481 42.7 182.95 6 213.905 1.47 166.97 7 213.520 23.46 1.43387 95.1 166.12 8 -834.787 0.21 164.30 9 351.588 11.67 1.43387 95.1 149.13 10 -2378.908 (variable) 146.68 11 274.898 10.36 1.43387 95.1 131.53 12 18647.577 0.21 131.17 13 197.643 12.46 1.43387 95.1 129.16 14 2346.661 (Variable) 128.33 15 152.277 9.37 1.61800 63.3 120.24 16 331.275 (Variable) 118.78 17* -335.080 1.84 2.00330 28.3 50.06 18 30.261 15.63 39.40 19 -31.989 1.21 1.71999 50.2 37.82 20 137.870 8.77 1.92286 18.9 40.10 21 -46.510 5.26 40.62 22 -37.511 1.67 1.88300 40.8 37.80 23 -60.834 (variable) 38.76 24 96.845 7.93 1.76385 48.5 57.01 25* 2003.641 8.00 56.91 26 1266.159 8.33 1.43875 94.7 57.33 27 -93.806 0.41 57.41 28 382.987 2.17 1.85478 24.8 55.90 29 104.575 (Variable) 54.91 30 112.876 7.32 1.49700 81.5 55.69 31 -291.208 2.34 1.84666 23.8 55.41 32 1002.458 0.17 55.19 33* 172.703 7.18 1.59522 67.7 55.10 34 -143.446 (variable) 54.76 35 (aperture) ∞ 3.00 31.03 36 -187.095 1.40 1.88300 40.8 29.91 37 38.099 1.32 29.12 38 36.175 5.47 1.89286 20.4 29.87 39 147.424 6.02 29.26 40 -42.633 1.50 1.80400 46.5 28.67 41 -56.720 7.30 29.10 42 -680.542 1.50 1.89190 37.1 28.56 43 34.213 4.56 1.78880 28.4 28.51 44 177.781 9.04 28.59 45 -103.323 1.50 1.88300 40.8 30.08 46 290.428 6.69 1.51742 52.4 30.82 47 -36.785 10.78 31.72 48 69.944 4.57 1.53172 48.8 32.09 49 -183.073 1.40 31.79 50 -91.276 1.50 1.89190 37.1 31.56 51 39.436 8.28 1.49700 81.5 31.59 52 -60.358 0.20 32.62 53 64.800 8.26 1.51633 64.1 33.98 54 -43.066 1.50 1.88300 40.8 33.98 55 -189.110 0.20 34.67 56 121.607 6.41 1.54814 45.8 35.00 57 -51.827 10.00 34.98 58 ∞ 33.00 1.60859 46.4 60.00 59 ∞ 13.20 1.51633 64.2 60.00 60 ∞ 13.27 60.00 Image plane ∞ Aspherical data Page 17 K =-2.00000e+00 A 4= 3.86699e-06 A 6=-2.18466e-09 A 8= 5.86719e-13 A10=-3.50266e-15 A12= 1.39895e-17 A14=-1.94494e-20 A16= 9.51845e-24 Page 25 K =-1.80745e+04 A 4= 7.68196e-07 A 6=-3.57069e-10 A 8= 4.36154e-13 A10=-2.81265e-16 A12= 7.50695e-20 Page 33 K =-8.98152e+01 A 4= 1.76801e-06 A 6=-2.69561e-09 A 8= 3.15027e-12 A10=-2.37636e-15 A12= 8.08405e-19 Various data Zoom ratio 67.50 Wide-angle, Medium, Telephoto Focal length 6.80 47.66 459.00 F-number 1.76 1.76 3.64 Half-angle [°] 38.97 6.58 0.69 Image height 5.50 5.50 5.50 Lens length 568.07 568.07 568.07 BF 13.27 13.27 13.27 d10 10.33 15.30 12.57 d14 0.50 5.66 4.99 d16 3.86 86.20 125.56 d23 217.74 83.57 4.00 d29 3.67 11.44 16.74 d34 2.49 36.42 74.73 Entrance pupil position 104.36 492.80 4892.32 Exit pupil position 152.27 152.27 152.27 Front principal point position 111.49 556.80 6867.04 Back principal point position 6.47 -34.38 -445.73 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 960128.67 57.00 8510.51 40078.13 2 11 281.14 23.03 3.72 -12.42 3 15 445.39 9.37 -4.82 -10.49 4 17 -20.53 34.38 2.93 -24.08 5 24 144.75 26.84 -4.62 -23.52 6 30 103.06 17.00 5.72 -5.35 7 35 41.62 148.60 58.02 5.00 The various values ​​in each numerical example are summarized in Table 1 below.

[0060] [Table 1]

[0061] [Imaging device] Figure 11 illustrates the outline of the imaging device (television camera system) using the zoom lens of each embodiment as the imaging optical system. Figure 11 is a schematic diagram of the main parts of the imaging device 125. The zoom lens 101 is one of the zoom lenses from Embodiments 1 to 5 and is detachably attached to the camera body 124.

[0062] The zoom lens 101 has a front group F, a variable magnification group LZ, and a rear group R for image formation. The front group F includes a focusing lens group. The variable magnification group LZ includes a group that moves along the optical axis during zooming and a group that moves along the optical axis to correct image plane fluctuations associated with zooming. The drive mechanism 114 is a drive mechanism such as a helicoid, cam, or actuator that moves the front lens group F along the optical axis. The drive mechanism 115 is a drive mechanism such as a helicoid, cam, or actuator that moves the zoom lens group LZ along the optical axis. Motors (driving means) 116, 117, and 118 electrically drive the drive mechanisms 114, 115, and the aperture diaphragm SP. Detectors 119, 120, and 121 are detectors such as encoders, potentiometers, or photosensors for detecting the position of the focusing lens group and the zoom lens group LZ on the optical axis, and the aperture diameter of the aperture diaphragm SP. Inside the camera body 123 are a glass block 109 corresponding to an optical filter or color separation prism, and an image sensor (photoelectric conversion element) 110 such as a CCD sensor or CMOS sensor that receives the subject image formed by the zoom lens 101.

[0063] Furthermore, CPUs 111 and 122 control various components of the camera body 123 and the zoom lens 101, respectively.

[0064] Thus, by applying the zoom lens of this disclosure to an imaging device, an imaging device with high optical performance can be obtained. This embodiment includes the following configuration. (Composition 1) A zoom lens having a positive refractive power front group including at least one lens group arranged sequentially from the object side to the image side, a negative refractive power second lens group that moves during zooming, a positive refractive power third lens group that moves during zooming, a positive refractive power fourth lens group that moves during zooming, and a fixed fifth lens group during zooming, wherein the spacing between adjacent lens groups changes during zooming, The aperture diaphragm is positioned between the fourth lens group and the fifth lens group, or within the fifth lens group. The aforementioned front group consists of a total of 5 to 8 lenses. The lens group that remains stationary during zooming is positioned closest to the object in the aforementioned front group. When the focal length of the front group at its wide-angle end is f1, the focal length of the second lens group is f2, the air-equivalent length of the distance along the optical axis from the lens surface closest to the object to the image plane is L, and the air-equivalent length of the distance along the optical axis from the aperture diaphragm to the image plane is Lr, -9.2 <f1 / f2<-5.5 0.20 <f1 / L<0.35 0.9 <f1 / Lr<2.0 A zoom lens characterized by satisfying the following conditional equation. (Configuration 2) The zoom lens according to configuration 1, characterized in that the front group includes a group of lenses that move toward the object when focusing from infinity to the closest end. (Composition 3) When the combined focal length of the third lens group and the fourth lens group is f34, -0.4 <f2 / f34<-0.2 A zoom lens according to configuration 1 or 2, characterized by satisfying the following conditional expression. (Composition 4) When the refractive index of the image-side lens in the aforementioned front group is NDL, 1.40 <ndl<1.65 A zoom lens according to any one of configurations 1 to 3, characterized by satisfying the following conditional expression. (Composition 5) When the lateral magnification at the wide-angle end and telephoto end of the second lens group are β2w and β2t, respectively, and the focal lengths at the wide-angle end and telephoto end of the zoom lens are fw and ft, respectively, 2.0 < (β2t / β2w) 2 ×(fw / ft)<5.0 A zoom lens according to any one of configurations 1 to 4, characterized by satisfying the following conditional expression. (Composition 6) When the distances along the optical axis from the image-side lens surface of the second lens group to the object-side lens surface of the third lens group at the wide-angle end and the telephoto end are m2 and m3, respectively, 0.8 < |m² / m³| < 2.5 A zoom lens according to any one of configurations 1 to 5, characterized by satisfying the following conditional expression. (Composition 7) When the focal length and refractive index of the lens closest to the object in the aforementioned front group are fg1 and ndg1, respectively, -4.0 <fg1 / f1<-1.0 1.80 <ndg1<1.95 A zoom lens according to any one of configurations 1 to 6, characterized by satisfying the following conditional expression. (Composition 8) When the focal lengths of the wide-angle and telephoto ends of the zoom lens are fw and ft, respectively, 1.5 <ft / f1<4.0 15 <f1 / fw<30 A zoom lens according to any one of configurations 1 to 8, characterized by satisfying the following conditional expression. (Composition 9) The zoom lens according to any one of configurations 1 to 8, characterized in that the third lens group moves along a convex trajectory toward the object when zooming. (Composition 10) A zoom lens characterized by having a positive refractive power front group including at least one lens group arranged sequentially from the object side to the image side, a negative refractive power second lens group that moves during zooming, a positive refractive power third lens group that moves during zooming, a positive refractive power fourth lens group that moves during zooming, and a fifth lens group that remains stationary during zooming, wherein the spacing between adjacent lens groups changes during zooming. (Composition 11) An imaging device characterized by comprising a zoom lens described in any one of configurations 1 to 10, and an image sensor that receives the image formed by the zoom lens.

[0065] While preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments, and various modifications and changes are possible within the scope of its essence. [Explanation of symbols]

[0066] L1 front group L2 Second lens group L3 Third lens group L4, the fourth lens group L5, the fifth lens group SP aperture diaphragm

Claims

1. A zoom lens having a positive refractive power front group including at least one lens group arranged sequentially from the object side to the image side, a negative refractive power second lens group that moves during zooming, a positive refractive power third lens group that moves during zooming, a positive refractive power fourth lens group that moves during zooming, and a fixed fifth lens group during zooming, wherein the spacing between adjacent lens groups changes during zooming, The aperture diaphragm is positioned between the fourth lens group and the fifth lens group, or within the fifth lens group. The aforementioned front group consists of a total of 5 to 8 lenses. The lens group that remains stationary during zooming is positioned closest to the object in the aforementioned front group. When the focal length of the front group at its wide-angle end is f1, the focal length of the second lens group is f2, the air-equivalent length of the distance along the optical axis from the lens surface closest to the object to the image plane is L, and the air-equivalent length of the distance along the optical axis from the aperture diaphragm to the image plane is Lr, -9.2<f1 / f2<-5.5 0.20<f1 / L<0.35 0.9<f1 / Lr<2.0 A zoom lens characterized by satisfying the following conditional equation.

2. The zoom lens according to claim 1, characterized in that the front group includes a group of lenses that move toward the object when focusing from infinity to the closest end.

3. When the combined focal length of the third lens group and the fourth lens group is f34, -0.4<f2 / f34<-0.2 A zoom lens according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

4. When the refractive index of the image-side lens in the aforementioned front group is ndl, 1.40<ndl<1.65 A zoom lens according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

5. When the lateral magnification at the wide-angle end and telephoto end of the second lens group are β2w and β2t, respectively, and the focal lengths at the wide-angle end and telephoto end of the zoom lens are fw and ft, respectively, 2.0<(β2t / β2w) ２ ×(fw / ft)<5.0 A zoom lens according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

6. When the distances along the optical axis from the image-side lens surface of the second lens group to the object-side lens surface of the third lens group at the wide-angle end and the telephoto end are m2 and m3, respectively, 0.8<|m2 / m3|<2.5 A zoom lens according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

7. When the focal length and refractive index of the lens closest to the object in the aforementioned front group are fg1 and ndg1, respectively, -4.0<fg1 / f1<-1.0 1.80<ndg1<1.95 A zoom lens according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

8. When the focal lengths of the wide-angle and telephoto ends of the zoom lens are fw and ft, respectively, 1.5<ft / f1<4.0 15<f1 / fw<30 A zoom lens according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

9. The zoom lens according to claim 1 or 2, characterized in that the third lens group moves along a convex trajectory toward the object when zooming.

10. A zoom lens characterized by having a positive refractive power front group including at least one lens group arranged sequentially from the object side to the image side, a negative refractive power second lens group that moves during zooming, a positive refractive power third lens group that moves during zooming, a positive refractive power fourth lens group that moves during zooming, and a fifth lens group that remains stationary during zooming, wherein the spacing between adjacent lens groups changes during zooming.

11. An imaging device characterized by comprising a zoom lens according to claim 1 or 2, and an image sensor that receives light from an image formed by the zoom lens.

Images