Zoom lens and imaging device having the same

Abstract

This provides a compact and lightweight zoom lens with a wide angle of view and high optical performance across the entire zoom range. [Solution] The zoom lens (1a~1e) consists of a first lens group (L1) with negative refractive power, an intermediate group (LM) containing one or more lens groups, and a final lens group (LR) with negative refractive power, arranged in order from the object side to the image side, and the spacing between adjacent lens groups changes when zooming. The first lens group includes at least three negative lenses. The thickness TD1 of the first lens group on the optical axis, the focal length f1 of the first lens group, the focal length fr of the final lens group, the amount of movement mr of the final lens group when zooming from the wide-angle end to the telephoto end, the amount of movement mf of the lens group arranged adjacent to the object side of the final lens group when zooming from the wide-angle end to the telephoto end, and the focal length fw of the zoom lens at the wide-angle end satisfy predetermined conditions.

Description

[Technical Field]

[0001] The present invention relates to a zoom lens and is suitable for digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, surveillance cameras, and the like. [Background technology]

[0002] In recent years, zoom lenses used in imaging devices have been required to have a wide field of view and high optical performance, as imaging devices have become more sophisticated. Furthermore, negative-lead zoom lenses, in which a group of lenses with negative refractive power precedes the lens element, are known as zoom lenses with a wide field of view at the wide-angle end.

[0003] As a negative-lead type zoom lens, Patent Document 1 discloses a zoom lens consisting of a first lens group and a second lens group with negative and positive refractive powers, arranged sequentially from the object side to the image side. Furthermore, Patent Document 2 discloses a mirrorless type zoom lens consisting of first to fourth lens groups with negative, positive, positive, and positive refractive powers, arranged sequentially from the object side to the image side. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 5110128 [Patent Document 2] Japanese Patent Publication No. 2020-042221 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, in the zoom lens disclosed in Patent Document 1, the focal length of the first lens group is set short in order to widen the angle, resulting in large distortion at the wide-angle end and deterioration of the peripheral image. In addition, the back focus and refractive power of the first lens group are not appropriate, making it difficult to further reduce the size of the front element or shorten the overall length. The zoom lens disclosed in Patent Document 2 has a short back focus and a refractive power arrangement that is suitable for shortening the overall length. However, all the lens groups following the first lens group have positive refractive power, making it difficult to narrow the position of the front principal point when considering the entire group of subsequent lenses toward the first lens group, making further miniaturization and weight reduction difficult.

[0006] To obtain a compact and lightweight zoom lens that offers high optical performance across the entire zoom range while also achieving a wide-angle view, it is crucial to appropriately set the refractive power and lens configuration of the first lens group, as well as the refractive power and positioning of the lens groups that follow the first lens group.

[0007] The present invention aims to provide a compact and lightweight zoom lens with a wide field of view and high optical performance across the entire zoom range, as well as an imaging device having the same. [Means for solving the problem]

[0008] A zoom lens as one aspect of the present invention comprises a first lens group with negative refractive power, an intermediate group including one or more lens groups, and a final lens group with negative refractive power, arranged sequentially from the object side to the image side, wherein the spacing between adjacent lens groups changes during zooming, and the first lens group includes at least three negative lenses, and when the thickness of the first lens group on the optical axis is TD1, the focal length of the first lens group is f1, the focal length of the final lens group is fr, the amount of movement of the final lens group during zooming from the wide-angle end to the telephoto end is mr, the amount of movement of the lens group arranged adjacent to the object side of the final lens group during zooming from the wide-angle end to the telephoto end is mf, and the focal length of the zoom lens at the wide-angle end is fw, 0.6 <TD1 2 / (f1×fr)<10.0 -10.0 < (mr - mf) / fw < -0.1 satisfies the conditional expression.

[0009] Other objects and features of the present invention will be described in the following embodiments.

Effects of the Invention

[0010] According to the present invention, it is possible to provide a small and lightweight zoom lens having a wide angle of view and high optical performance in the entire zoom range, and an imaging device having the same.

Brief Description of the Drawings

[0011] [Figure 1] It is a cross-sectional view of the zoom lens at the wide-angle end in Example 1. [Figure 2] It is an aberration diagram of the zoom lens at (A) the wide-angle end, (B) the intermediate zoom position, and (C) the telephoto end in Example 1. [Figure 3] It is a cross-sectional view of the zoom lens at the wide-angle end in Example 2. [Figure 4] It is an aberration diagram of the zoom lens at (A) the wide-angle end, (B) the intermediate zoom position, and (C) the telephoto end in Example 2. [Figure 5] It is a cross-sectional view of the zoom lens at the wide-angle end in Example 3. [Figure 6] It is an aberration diagram of the zoom lens at (A) the wide-angle end, (B) the intermediate zoom position, and (C) the telephoto end in Example 3. [Figure 7] It is a cross-sectional view of the zoom lens at the wide-angle end in Example 4. [Figure 8] It is an aberration diagram of the zoom lens at (A) the wide-angle end, (B) the intermediate zoom position, and (C) the telephoto end in Example 4. [Figure 9] It is a cross-sectional view of the zoom lens at the wide-angle end in Example 5. [Figure 10] It is an aberration diagram of the zoom lens at (A) the wide-angle end, (B) the intermediate zoom position, and (C) the telephoto end in Example 5. [Figure 11]It is a schematic diagram of an imaging device equipped with a zoom lens in each embodiment.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the zoom lens of the present invention and an imaging device having the same will be described based on the accompanying drawings.

[0013] FIG. 1 is a cross-sectional view at the wide-angle end of the zoom lens 1a in Embodiment 1. FIGS. 2(A), 2(B), and 2(C) are vertical aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end of the zoom lens 1a, respectively. The zoom lens 1a is a zoom lens with a zoom ratio of 1.9 times and an F-number of about 4.12. The total angle of view at the wide-angle end of the zoom lens 1a is 128 degrees, and the total angle of view at the telephoto end is 102 degrees.

[0014] FIG. 3 is a cross-sectional view at the wide-angle end of the zoom lens 1b in Embodiment 2. FIGS. 4(A), 4(B), and 4(C) are vertical aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end of the zoom lens 1b, respectively. The zoom lens 1b is a zoom lens with a zoom ratio of 1.9 times and an F-number of about 4.12. The total angle of view at the wide-angle end of the zoom lens 1b is 128 degrees, and the total angle of view at the telephoto end is 102 degrees.

[0015] FIG. 5 is a cross-sectional view at the wide-angle end of the zoom lens 1c in Embodiment 3. FIGS. 6(A), 6(B), and 6(C) are vertical aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end of the zoom lens 1c, respectively. The zoom lens 1c is a zoom lens with a zoom ratio of 1.9 times and an F-number of about 4.12. The total angle of view at the wide-angle end of the zoom lens 1c is 134 degrees, and the total angle of view at the telephoto end is 102 degrees.

[0016] Figure 7 is a cross-sectional view of the zoom lens 1d at the wide-angle end in Example 4. Figures 8(A), 8(B), and 8(C) are longitudinal aberration diagrams of the zoom lens 1d at the wide-angle end, intermediate zoom position, and telephoto end, respectively. The zoom lens 1d is a zoom lens with a zoom ratio of 1.7x and an F-number of approximately 4.12. The total angle of view at the wide-angle end of the zoom lens 1d is 124 degrees, and the total angle of view at the telephoto end is 102 degrees.

[0017] Figure 9 is a cross-sectional view of the zoom lens 1e at the wide-angle end in Example 5. Figures 10(A), 10(B), and 10(C) are longitudinal aberration diagrams of the zoom lens 1e at the wide-angle end, intermediate zoom position, and telephoto end, respectively. The zoom lens 1e is a zoom lens with a zoom ratio of 1.7x and an F-number of approximately 4.12. The total angle of view at the wide-angle end of the zoom lens 1e is 125 degrees, and the total angle of view at the telephoto end is 102 degrees.

[0018] The zoom lenses 1a to 1e in each embodiment are zoom lenses used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, and surveillance cameras. The zoom lenses 1a to 1e in each embodiment can also be used as projection optical systems for projection devices (projectors).

[0019] In the cross-sectional lens views of Figures 1, 3, 5, 7, and 9, the left side is the object side (front) and the right side is the image side (rear). The zoom lenses 1a to 1e of each embodiment are 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. That is, in the zoom lenses 1a to 1e of each embodiment, the distance between adjacent lens groups changes when zooming from the wide-angle end to the telephoto end. A lens group may consist of a single lens or multiple lenses. Furthermore, a lens group may include an aperture diaphragm.

[0020] In each lens cross-section diagram, Li represents the i-th lens group (where i is a natural number) from the object side among the lens groups included in zoom lenses 1a to 1e. Also, Gmi (where i is a natural number) is the i-th negative refractive power lens (negative lens) from the object side among the lenses included in the first lens group L1 (where i is a natural number). LR is the final negative refractive power lens group located furthest towards the image side in zoom lenses 1a to 1e. LF is the lens group located adjacent to the final lens group LR on the object side.

[0021] SP is the aperture diaphragm (diaphragm group). IP is the image plane, and when the zoom lenses 1a to 1e of each embodiment are used as the shooting optical system of a digital still camera or digital video camera, the imaging surface of a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor is placed on it. When the zoom lenses 1a to 1e of each embodiment are used as the shooting optical system of a silver halide film camera, a photosensitive surface corresponding to the film surface is placed on the image plane IP. In a projector, IP is the object plane, and the modulation surface (display surface) of a light modulation element (display element) such as a liquid crystal panel is placed on the object plane IP.

[0022] In the zoom lenses 1a to 1e of each embodiment, the lens groups move as indicated by the arrows in each lens cross-sectional view when zooming from the wide-angle end to the telephoto end. The aperture diaphragm SP moves as indicated by the arrows when zooming. The arrows related to focus indicate the direction of movement of the lens groups when focusing from infinity to near distance.

[0023] In the spherical aberration diagrams in Figures 2, 4, 6, 8, and 10, Fno is the F-number and indicates the amount of spherical aberration for the d-line (wavelength 587.6 nm) and g-line (wavelength 435.8 nm). In the astigmatism diagram, ΔS indicates the amount of astigmatism at the sagittal image plane, and ΔM indicates the amount of astigmatism at the meridional image plane. The distortion diagram shows the amount of distortion for the d-line. The chromatic aberration diagram shows the amount of chromatic aberration at the g-line. ω is the imaging half-angle of view (°).

[0024] Next, we will describe the characteristic configurations of the zoom lenses 1a to 1e in each embodiment.

[0025] Each embodiment of the zoom lenses 1a to 1e consists of a first lens group L1 with negative refractive power, an intermediate group LM containing one or more lens groups, and a final lens group LR with negative refractive power, arranged in order from the object side to the image side. Each embodiment of the zoom lenses 1a to 1e is a zoom lens in which the spacing between adjacent lens groups changes during zooming.

[0026] In the zoom lenses 1a to 1e of each embodiment, the first lens group L1 includes at least three negative lenses (negative meniscus lenses Gm1, Gm2, and Gm3). This configuration maximizes the negative refractive power of the first lens group L1 while minimizing distortion aberrations generated in the first lens group L1. Preferably, the at least three negative lenses included in the first lens group L1 are arranged sequentially from the object side to the image side.

[0027] The zoom lenses 1a to 1e in each embodiment are so-called negative lead type zoom lenses. Positive lead type zoom lenses are advantageous for achieving a high zoom ratio, but are disadvantageous for wide-angle applications where the entire angle of view at the wide-angle end exceeds 100 degrees.

[0028] In the zoom lenses 1a to 1e of each embodiment, the final lens group LR has negative refractive power. Generally, wide-angle zoom lenses are known to have a so-called retrofocus type refractive power arrangement, which consists of a lens group with negative refractive power and a lens group with positive refractive power. In the zoom lenses 1a to 1e of each embodiment, by making the final lens group LR have negative refractive power, the principal point position of the subsequent group that has positive refractive power as a whole, following the first lens group L1, is moved towards the object side, thereby reducing the overall length of the lens.

[0029] Furthermore, the zoom lenses 1a to 1e of each embodiment satisfy the following conditions (1) and (2).

[0030] 0.60 <TD1 2 / (f1×fr)<10.00 ···(1) -10.0<(mr-mf) / fw<-0.1 ···(2) Here, TD1 is the thickness (total thickness) of the first lens group L1 along the optical axis. The total thickness TD1 of the first lens group L1 is the length along the optical axis from the lens surface closest to the object to the lens surface closest to the image in the first lens group L1. f1 is the focal length of the first lens group L1. fr is the focal length of the final lens group LR. mr is the amount of movement of the final lens group LR when zooming from the wide-angle end to the telephoto end. mf is the amount of movement of the lens group LF, which is located adjacent to the object side of the final lens group LR, when zooming from the wide-angle end to the telephoto end. fw is the focal length of the zoom lenses 1a to 1e at the wide-angle end.

[0031] The amount of movement of the lens group corresponds to the difference between its position on the optical axis at the wide-angle end and its position on the optical axis at the telephoto end. The sign of the amount of movement is positive when the lens group is positioned closer to the object at the telephoto end compared to the wide-angle end, and negative when the lens group is positioned closer to the image at the telephoto end compared to the wide-angle end.

[0032] Conditional equation (1) specifies the total thickness TD1 and focal length f1 of the first lens group L1, and the focal length fr of the final lens group LR, in order to make the zoom lenses 1a to 1e smaller and lighter while effectively correcting field curvature and distortion at the wide-angle end.

[0033] If the upper limit of condition (1) is exceeded and the total thickness TD1 of the first lens group L1 becomes large, more negative meniscus lenses can be placed to correct distortion, which is advantageous in terms of optical performance, but it leads to an increase in the overall length of the lens. Also, the increased thickness of the first lens group L1 increases the distance from the first lens group L1 to the entrance pupil position, leading to an increase in the diameter of the front element. Alternatively, if the upper limit of condition (1) is exceeded and the absolute value of the focal length f1 of the first lens group L1 becomes small, the refractive power of the first lens group L1 becomes too strong, making it difficult to correct the distortion and chromatic aberration at the wide-angle end that occur in the first lens group L1. In addition, the Petzval sum of the entire lens becomes too strong in the negative direction, making it difficult to correct field curvature across the entire zoom range. Alternatively, if the upper limit of condition (1) is exceeded and the absolute value of the focal length fr of the final lens group LR becomes small, it becomes necessary to unnecessarily increase the refractive power of the lens group with positive refractive power on the object side of the final lens group LR from the perspective of spherical aberration and field curvature. Also, if the negative refractive power of the final lens group LR is increased, the angle of incidence of light rays at peripheral image height becomes too large from the perspective of shading.

[0034] If the total thickness TD1 of the first lens group L1 falls below the lower limit of condition (1), it is advantageous for miniaturization and weight reduction, but it becomes difficult to correct distortion and field curvature occurring in the first lens group L1 while maintaining a wide-angle focal length. Alternatively, if the absolute value of the focal length f1 of the first lens group L1 falls below the lower limit of condition (1), it is advantageous for correcting aberrations such as distortion and field curvature, but it becomes difficult to achieve a wide angle of view. Alternatively, if the absolute value of the focal length fr of the final lens group LR falls below the lower limit of condition (1), it becomes difficult to move the principal point position of the lens group following the first lens group L1 towards the object, making it difficult to reduce the overall size of the lens.

[0035] Conditional equation (2) specifies the amount of movement mr of the final lens group LR, the amount of zooming movement mf of lens group LF, and the wide-angle end focal length fw in order to suppress the overall lens length at the telephoto end while effectively correcting field curvature aberration across the entire zoom range. Conditional equation (2) takes a negative value. In other words, the final lens group LR moves relatively away from lens group LF during zooming.

[0036] If the value falls below the lower limit of condition (2), and the difference between the zooming movement mr of the final lens group LR and the movement mf of lens group LF becomes large, the final lens group LR will be too close to the image at the telephoto end, making it difficult to correct distortion at the telephoto end. Alternatively, if the value falls below the lower limit of condition (2) and the focal length fw at the wide-angle end becomes small, the angle becomes too wide, resulting in an undesirablely large front element diameter.

[0037] If the upper limit of condition (2) is exceeded and the difference between the zooming movement mr of the final lens group LR and the movement mf of lens group LF becomes small, the final lens group LR extends too far towards the object at the telephoto end, making it difficult to achieve a sufficient magnification ratio. As a result, it becomes difficult to achieve the desired telephoto focal length. Alternatively, if the upper limit of condition (2) is exceeded and the focal length fw at the wide-angle end becomes large, it becomes difficult to obtain the desired angle of view at the wide-angle end.

[0038] Next, we will describe the conditions that are preferably satisfied in the zoom lenses 1a to 1e of each embodiment. It is preferable that the zoom lenses 1a to 1e of each embodiment satisfy one or more of the following conditional equations (3) to (10).

[0039] 0.5 <TD1 / skw<5.0 ···(3) -12.0 <fr / fw<-2.0 ···(4) 2.0 <POw / fw<10.0 ···(5) -8.0 <fave / fw<-2.0 ···(6) 1.0<(R2+R1) / (R2-R1)<10.0 (7) -3.0 <ft / f1<-0.5 ···(8) 0.05 <TDr / fw<0.50 ···(9) 2.0 <TTDt / ft<10.0 ···(10) Here, skw is the back focus of zoom lenses 1a to 1e at the wide-angle end. POw is the distance from the image plane IP to the position of the exit pupil at the wide-angle end of zoom lenses 1a to 1e. The sign of POw, the distance from the image plane IP to the position of the exit pupil, is negative when the exit pupil is located on the image side of the image plane IP, and positive when it is located on the object side. fave is the average focal length of at least three negative lenses (Gm1, Gm2, Gm3) included in the first lens group L1. R1 is the radius of curvature of the object-side lens surface of the lens located furthest towards the image in the final lens group LR. R2 is the radius of curvature of the image-side lens surface of the lens located furthest towards the image in the final lens group LR. ft is the focal length of zoom lenses 1a to 1e at the telephoto end. TDr is the thickness (total thickness) of the final lens group LR along the optical axis. TTDt is the total lens length of zoom lenses 1a to 1e at the telephoto end.

[0040] Conditional equation (3) defines the relationship between the total thickness TD1 of the first lens group L1 and the back focus skw at the wide-angle end in order to reduce the overall length of the lens while effectively correcting distortion at the wide-angle end.

[0041] If the upper limit of condition (3) is exceeded and the total thickness TD1 of the first lens group L1 increases, more negative lenses can be placed to correct distortion, which is advantageous in terms of optical performance, but it leads to an increase in the overall length of the lens, which is undesirable. Also, if the first lens group L1 becomes thicker, the distance from the first lens group L1 to the entrance pupil position increases, leading to an increase in the diameter of the front element, which is undesirable. Alternatively, if the back focus skw becomes small, the mechanical layout of the connection part between the zoom lens (imaging optical system) 1a~1e and the camera body becomes difficult, which is undesirable.

[0042] On the other hand, if the total thickness TD1 of the first lens group L1 falls below the lower limit of condition (3), it is advantageous for miniaturizing the overall length of the lens, but it is undesirable because it becomes difficult to correct distortion while maintaining a wide angle of view. Also, if a wide angle of view is maintained while keeping the total thickness TD1 of the first lens group L1 small, it is necessary to increase the refractive power of the first lens group L1, which worsens field curvature and chromatic aberration, and is undesirable. Alternatively, if the back focus skw becomes large, it becomes necessary to secure an unnecessary back focus space, which is undesirable from the viewpoint of miniaturizing the overall length of the lens.

[0043] Conditional equation (4) specifies the focal length fr of the final lens group LR and the focal length fw of the zoom lenses 1a to 1e at the wide-angle end in order to reduce the overall length of the lens.

[0044] If the value falls below the lower limit of condition (4) and the absolute value of the focal length fr of the final lens group LR becomes large, the principal point position of the entire subsequent group, which is positioned closer to the image than the first lens group L1, shifts towards the image side, thus weakening the retrofocus arrangement at the wide-angle end. As a result, the overall length of the lens at the wide-angle end becomes longer, making it difficult to achieve the desired reduction in overall lens length, which is undesirable. Alternatively, if the value falls below the lower limit of condition (4) and the focal length fw of the zoom lenses 1a to 1e at the wide-angle end becomes small, the angle becomes too wide, worsening chromatic aberration and field curvature, as well as increasing the diameter of the front element, which is undesirable.

[0045] If the absolute value of the focal length fr of the final lens group LR decreases beyond the upper limit of condition (4), it is advantageous for miniaturizing the overall length of the lens at the wide-angle end. However, the incident angle of peripheral light rays reaching the image plane IP becomes too large, resulting in increased shading at the image plane IP, which is undesirable. Furthermore, the field curvature at the wide-angle end also worsens, which is undesirable. Alternatively, if the focal length fw at the wide-angle end increases beyond the upper limit of condition (4), it is undesirable because the desired angle of view cannot be obtained at the wide-angle end.

[0046] Conditional equation (5) defines the relationship between the distance POw to the exit pupil at the wide-angle end and the focal length fw of the zoom lenses 1a to 1e at the wide-angle end in order to ensure high telecentricity. If the distance POw to the exit pupil becomes larger than the upper limit of conditional equation (5), the refractive power of the final lens group LR tends to increase, making it difficult to sufficiently suppress field curvature aberration, which is undesirable. On the other hand, if the distance POw to the exit pupil becomes smaller than the lower limit of conditional equation (5), the angle of incidence of light rays at peripheral image height becomes too large, which is undesirable from the viewpoint of shading. Alternatively, the focal length fw at the wide-angle end becomes large, making it difficult to achieve the desired wide-angle, which is undesirable.

[0047] Conditional equation (6) specifies the average focal length fava of at least three negative lenses (Gm1, Gm2, Gm3) included in the first lens group L1 and the focal length fw at the wide-angle end in order to achieve both good aberration correction at the wide-angle end and a smaller front element diameter.

[0048] If the absolute value of the average focal length fave becomes small, exceeding the upper limit of condition (6), the negative refractive force on the object side in the first lens group L1 becomes too strong, making it difficult to adequately correct chromatic aberration and distortion at the wide-angle end, which is undesirable. Alternatively, if the focal length fw at the wide-angle end becomes large, exceeding the upper limit of condition (6), it becomes difficult to obtain the desired angle of view at the wide-angle end, which is also undesirable.

[0049] If the absolute value of the average focal length fave increases below the lower limit of condition (6), the refractive power of at least three negative lenses included in the first lens group L1 weakens, which is advantageous in terms of aberration correction. However, the entrance pupil of the first lens group L1 moves towards the image side, and the front element diameter becomes larger, which is undesirable. Alternatively, if the focal length fw at the wide-angle end decreases below the lower limit of condition (6), although the angle of view widens, it becomes difficult to correct the distortion and chromatic aberration occurring in the first lens group L1, which is undesirable.

[0050] Conditional equation (7) defines the shape factor of the lens positioned furthest towards the image side of the final lens group LR in order to achieve appropriate aberration correction in the final lens group LR. The range of conditional equation (7) indicates that the lens positioned furthest towards the image side has a meniscus shape that is convex towards the image side. If the meniscus shape of the lens positioned furthest towards the image side becomes too strong, exceeding the upper limit of conditional equation (7), it becomes difficult to correct field curvature aberration at the wide-angle end, which is undesirable. If the meniscus shape of the lens positioned furthest towards the image side becomes too weak, falling below the lower limit of conditional equation (7), it becomes difficult to correct distortion aberration at the telephoto end, which is also undesirable. Furthermore, since the shape of the lens positioned furthest towards the image side becomes concave towards the image side, it becomes difficult to eliminate ghosting and flare caused by field reflections, which is also undesirable.

[0051] Conditional equation (8) specifies the focal length ft at the telephoto end and the focal length f1 of the first lens group L1 in order to obtain the desired zoom magnification.

[0052] If the focal length ft at the telephoto end becomes large, falling below the lower limit of condition (8), it becomes difficult to correct aberrations at the telephoto end, especially chromatic aberration, which is undesirable. Alternatively, if the absolute value of the focal length f1 of the first lens group L1 becomes small, falling below the lower limit of condition (8), the refractive power of the first lens group L1 becomes too strong, the back focus at the wide-angle end becomes long, which is undesirable from the viewpoint of miniaturizing the overall lens length. Furthermore, it becomes difficult to cancel out chromatic aberration occurring at the wide-angle end with subsequent lens groups, which is undesirable.

[0053] If the focal length ft at the telephoto end becomes smaller than the upper limit of condition (8), it is undesirable because the desired zoom magnification cannot be obtained. Alternatively, if the absolute value of the focal length f1 of the first lens group L1 becomes larger than the upper limit of condition (8), the positive refractive power of the entire lens becomes too strong, making it difficult to control the Petzval sum and making it difficult to obtain the desired optical performance, which is undesirable.

[0054] Conditional equation (9) specifies the total thickness TDr of the final lens group LR and the focal length fw at the wide-angle end in order to maintain the miniaturization of the overall lens length.

[0055] If the total thickness TDr of the final lens group LR exceeds the upper limit of condition (9), the negative refractive power of the final lens group LR increases. Therefore, in order to secure the necessary positive refractive power for the entire subsequent group, the thickness of the subsequent group increases, which is undesirable from the standpoint of miniaturization and weight reduction. Alternatively, if the focal length fw at the wide-angle end decreases by exceeding the upper limit of condition (9), although the angle of view is widened, it becomes difficult to suppress distortion and chromatic aberration at the wide-angle end, which is undesirable.

[0056] If the total thickness TDr of the final lens group LR falls below the lower limit of condition (9), it becomes difficult to manufacture a thin lens from a manufacturing perspective, and it becomes difficult to adequately correct field curvature aberration at the wide-angle end, which is undesirable. Alternatively, if the focal length fw at the wide-angle end becomes large, falling below the lower limit of condition (9), it becomes difficult to obtain the desired angle of view at the wide-angle end, which is undesirable.

[0057] Conditional equation (10) specifies the total lens length TTDt and focal length ft at the telephoto end of the zoom lenses 1a to 1e at the telephoto end in order to suppress the overall lens length at the telephoto end.

[0058] If the overall lens length TTDt at the telephoto end exceeds the upper limit of condition (10), it is undesirable from the standpoint of miniaturization and weight reduction. Alternatively, if the focal length ft at the telephoto end exceeds the upper limit of condition (10), it becomes impossible to obtain the desired zoom magnification, which is also undesirable.

[0059] If the lens length TTDr at the telephoto end falls below the lower limit of condition (10), it becomes necessary to ensure a larger movement of the first lens group L1 from the wide-angle end. This tends to lead to an increase in the front element diameter, which is undesirable. Alternatively, if the focal length ft at the telephoto end falls below the lower limit of condition (10), the zoom ratio increases, but it becomes difficult to suppress zoom variations in chromatic aberration and field curvature from the wide-angle end to the telephoto end, which is undesirable.

[0060] Furthermore, it is more preferable that the numerical ranges of conditional expressions (1) to (10) be within the ranges of the following conditional expressions (1a) to (10a).

[0061] 0.61 <TD1 2 / (f1×fr)<8.00 ···(1a) -5.00<(mr-mf) / fw<-0.11 ···(2a) 1.0 <TD1 / skw<4.0 ···(3a) -11.0 <fr / fw<-3.0 ···(4a) 2.5 <POw / fw<6.0 ···(5a) -6.0 <fave / fw<-3.0 ···(6a) 1.1<(R2+R1) / (R2-R1)<5.0 (7a) -2.00 <ft / f1<-0.75 ···(8a) 0.075 <TDr / fw<0.300 ···(9a) 3.0 <TTDt / ft<7.0 ···(10a) Furthermore, it is even more preferable that the numerical ranges of conditional expressions (1) to (10) be within the ranges of the following conditional expressions (1b) to (10b).

[0062] 0.62 <TD1 2 / (f1×fr)<3.00 ···(1b) -1.00<(mr-mf) / fw<-0.13 (2b) 1.5 <TD1 / skw<3.0 ···(3b) -10.0 <fr / fw<-5.0 ···(4b) 3.0 <POw / fw<5.0 ···(5b) -5.0 <fave / fw<-4.0 ···(6b) 1.3<(R2+R1) / (R2-R1)<4.0 (7b) -1.5 <ft / f1<-1.0 ···(8b) 0.09 <TDr / fw<0.20 ···(9b) 5.0 <TTDt / ft<6.0 ···(10b) Next, we will describe the preferred configurations for the zoom lenses 1a to 1e of each embodiment.

[0063] In the zoom lenses 1a to 1e of each embodiment, it is preferable that the final lens group LR consists of a single negative refractive power lens. By making the final lens group LR, which has a negative refractive power among the subsequent groups on the image side of the first lens group L1, a single lens, it is advantageous to miniaturize the entire subsequent group.

[0064] Furthermore, it is preferable that the final lens group LR has an aspherical surface. By setting an aspherical surface in the final lens group LR, where the light beams for peripheral image height and central image height are separated, field curvature aberration at the wide-angle end can be effectively corrected.

[0065] Next, the lens configurations of the zoom lenses 1a to 1e in each embodiment will be described.

[0066] The zoom lens 1a of Example 1 and the zoom lens 1b of Example 2 are four-group zoom lenses consisting of a first lens group L1 to a fourth lens group L4 with negative, positive, positive, and negative refractive powers, arranged sequentially from the object side to the image side. In zoom lenses 1a and 1b, the aperture diaphragm SP is located on the object side of the second lens group L2. The final lens group LR is the fourth lens group L4, and the lens group LF, located adjacent to the object side of the final lens group LR, is the third lens group L3.

[0067] The first lens group L1 moves toward the image when zooming from the wide-angle end to the telephoto end. The aperture diaphragm SP, the second lens group L2, and the third lens group L3 move toward the object when zooming from the wide-angle end to the telephoto end. The second lens group L2 and the third lens group L3 (LF) move so that their distance from each other increases during zooming. The fourth lens group L4 (LR) moves toward the object when zooming so that its distance from the third lens group L3 increases. In addition, the second lens group L2 moves during focusing.

[0068] The zoom lens 1c of Example 3 is a three-group zoom lens consisting of a first lens group L1, a second lens group L2 (LF), and a third lens group L3 (LR), arranged in order from the object side to the image side, with negative, positive, and negative refractive powers. The aperture diaphragm SP is located on the object side of the second lens group L2.

[0069] During zooming from the wide-angle end to the telephoto end, the first lens group L1 moves toward the image, and the second lens group L2(LF) moves toward the object so that the distance between it and the first lens group L1 decreases. During zooming, the third lens group L3(LR) moves toward the object so that the distance between it and the second lens group L2(LF) increases. Also, during focusing, the single positive lens located closest to the image in the first lens group L1 moves.

[0070] The zoom lens 1d in Example 4 is a four-group zoom lens consisting of the first lens group L1 to the fourth lens group L4, arranged in order from the object side to the image side, with negative, positive, positive, and negative refractive powers. The aperture diaphragm SP is located on the object side of the second lens group L2.

[0071] During zooming from the wide-angle end to the telephoto end, the first lens group L1 moves towards the image, and the second lens group L2 moves towards the object. The third lens group L3 (LF) moves so that its distance from the second lens group becomes smaller. The fourth lens group L4 (LR) remains stationary during zooming. Also, the second lens group L2 moves during focusing.

[0072] The zoom lens 1e of Example 5 is a five-group zoom lens consisting of the first lens group L1 to the fifth lens group L5, arranged in order from the object side to the image side, with refractive powers of negative, positive, positive, negative, and negative. The aperture diaphragm SP is located on the object side of the second lens group L2.

[0073] When zooming from the wide-angle end to the telephoto end, the first lens group L1 moves towards the image, and the second lens group L2 moves towards the object. The third lens group L3 moves towards the object so that the distance between it and the second lens group L2 decreases. The fourth lens group L4 (LF) moves towards the object so that the distance between it and the third lens group L3 increases. The fifth lens group L5 (LR) remains stationary during zooming. Also, the second lens group L2 moves during focusing.

[0074] The numerical values ​​corresponding to Examples 1 to 5 are shown below.

[0075] 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 the optical element. 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, respectively. νd = (Nd-1) / (NF-NC) It is represented as follows.

[0076] In each numerical example, d, focal length (mm), F-number, and half-angle of view (°) are all values ​​when the zoom lenses 1a to 1e of each example are focused on an object at infinity. "BF" (back focus) is the distance along the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image plane, expressed in terms of air equivalent length. "Total lens length" is the length obtained by adding the back focus to the distance along the optical axis from the frontmost lens surface (the lens surface closest to the object) to the final surface of the zoom lens. "Lens group" includes not only cases where it is composed of multiple lenses, but also cases where it is composed of a single lens.

[0077] When the optical surface is an aspherical surface, an asterisk (*) is attached to the right side of the surface number. The aspherical shape is expressed as follows when X is the displacement amount from the vertex of the surface in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial curvature radius, k is the conic constant, and A4, A6, A8, A10, A12, and A14 are the aspherical coefficients of each order: x=(h 2 / R) / [1+{1-(1+k)(h / R) 2} 1 / 2 +A4×h 4 +A6×h 6 +A8×h 8 +A10×h 10 +A12×h 12 +A14×h 14 Here, "e±XX" in each aspherical coefficient means "×10± XX ". (Numerical Example 1) Unit: mm Surface Data Surface Number r d nd νd 1* 72.063 2.90 1.80400 46.6 2* 26.089 5.22 3 30.802 1.40 2.00100 29.1 4 15.833 7.94 5 74.154 1.30 1.72916 54.7 6 17.697 5.96 7 -50.904 1.30 1.49700 81.5 8 19.613 0.20 9 19.629 6.63 1.64769 33.8 10 -52.032 (Variable) 11 (Aperture) ∞ 1.27 12 15.207 1.00 1.98612 16.5 13 11.273 6.70 1.51742 52.4 14 -17.526 1.00 1.90043 37.4 15 16.259 4.01 1.80810 22.8 16 -35.635 (variable) 17 14.359 1.20 2.05090 26.9 18 10.914 7.82 1.49700 81.5 19 -56.745 0.15 20 20.172 1.20 1.95375 32.3 21 10.293 8.27 1.43875 94.7 22 216.278 (variable) 23* -44.874 1.50 2.00100 29.1 24 -241.108 (variable) Image plane ∞ Aspherical data Front page K = 0.00000e+000 A 4= 1.33902e-005 A 6= 2.91057e-008 A8=-1.28735e-010 A10=2.51334e-013 A12=-2.33449e-016 A14 = 9.78493e-020 2nd side K =-2.18793e+000 A 4= 1.80881e-005 A 6= 7.96064e-008 A8= 1.06798e-010 A10=-1.71074e-012 A12= 5.08897e-015 A14 = -4.61662e-018 Page 23 K = 0.00000e+000 A 4=-5.76115e-005 A 6= 1.78402e-008 A8=-1.18082e-009 A10=-3.50838e-012 A12=8.05514e-014 Various data Zoom ratio 1.88 Wide-angle, Medium, Telephoto Focal length 9.27 13.03 17.46 F-number 4.12 4.12 4.12 Half-angle (°): 63.98, 56.92, 51.10 Image height 19.00 20.00 21.64 Lens length: 108.47, 102.77, 100.80 BF 15.71 19.67 23.00 d10 20.01 8.87 1.45 d16 2.69 2.84 2.59 d22 3.08 4.43 6.79 d24 15.71 19.67 23.00 Zoom lens group data Group starting plane focal length 1 1 -14.55 2 11 49.14 3 17 32.72 4 23 -55.29 (Numerical Example 2) Unit: mm Surface data Face number rd nd νd 1* 47.256 2.20 1.72916 54.7 2* 17.118 2.79 3 24.198 1.40 2.00100 29.1 4 15.482 9.78 5 93.291 1.30 1.72916 54.7 6 17.451 5.47 7 -89.287 1.30 1.49700 81.5 8 25.838 0.20 9 22.822 5.58 1.73800 32.3 10 -84.298 (variable) 11 (aperture) ∞ 1.24 12 16.172 1.00 1.98612 16.5 13 11.597 5.85 1.51742 52.4 14 -16.472 1.00 1.90043 37.4 15 16.494 3.89 1.80810 22.8 16 -32.381 (variable) 17 15.972 1.20 2.05090 26.9 18 12.131 8.38 1.49700 81.5 19 -36.138 0.15 20 20.739 1.20 1.95375 32.3 21 10.634 11.55 1.43875 94.7 22 51.020 (Variable) 23* -42.509 1.50 2.00069 25.5 24 -81.533 (variable) Image plane ∞ Aspherical data Front page K = 0.00000e+000 A 4= 3.68563e-006 A 6= 1.13383e-008 A8=-5.34353e-011 A10=9.92130e-014 A12=-9.28575e-017 A14 = 3.46574e-020 2nd side K =-2.88595e+000 A 4= 4.69727e-005 A 6=-2.52131e-008 A8= 5.96275e-011 A10=-4.24223e-013 A12= 4.44692e-016 A14 = 2.58187e-020 Page 23 K = 0.00000e+000 A 4=-5.67278e-005 A 6= 1.43835e-007 A 8=-3.07928e-009 A10= 9.76724e-012 A12= 1.90744e-014 Various data Zoom ratio 1.88 Wide-angle, Medium, Telephoto Focal length 9.28 13.27 17.46 F-number 4.12 4.12 4.12 Half-angle (°): 63.97, 56.44, 51.10 Image height 19.00 20.00 21.64 Lens length: 106.59 mm, 99.64 mm, 98.05 mm BF 13.00 17.96 23.00 d10 20.04 8.07 1.47 d16 3.45 2.91 2.24 d22 3.11 3.72 4.37 d24 13.00 17.96 23.00 Zoom lens group data Group starting plane focal length 1 1 -15.92 2 11 53.93 3 17 34.41 4 23 -90.49 (Numerical Example 3) Unit: mm Surface data Face number rd nd νd 1* 41.524 2.00 1.79490 47.8 2* 18.041 5.22 3 27.945 1.20 2.00100 29.1 4 14.785 5.44 5 40.461 1.00 1.72916 54.7 6 16.136 6.21 7 -32.454 0.80 1.49700 81.5 8 21.581 0.20 9 21.295 5.64 1.74171 35.7 10 -54.446 (variable) 11 (aperture) ∞ 1.29 12 17.175 1.00 1.98612 16.5 13 12.309 5.39 1.51742 52.4 14 -16.210 1.00 1.90043 37.4 15 13.455 5.90 1.80810 22.8 16 -33.138 0.15 17 14.137 1.20 2.05090 26.9 18 10.995 8.00 1.49700 81.5 19 -39.495 0.15 20 22.991 1.20 1.95375 32.3 21 9.977 11.97 1.43875 94.7 22 -106.448 (variable) 23* 55.339 1.20 2.00100 29.1 24 29.465 (Variable) Image plane ∞ Aspherical data Front page K = 0.00000e+000 A 4= 1.92621e-005 A 6=-1.86286e-008 A 8=-8.89542e-011 A10= 4.12893e-013 A12=-5.43799e-016 A14 = 2.32884e-019 2nd side K =-3.02767e+000 A 4= 6.83449e-005 A 6=-8.55642e-008 A8= 7.17943e-010 A10=-6.79416e-012 A12= 2.84840e-014 A14 = -3.86250e-017 Page 23 K = 0.00000e+000 A 4=-3.68849e-005 A 6= 9.41564e-009 A8= 1.14340e-009 A10=-1.58117e-011 A12= 8.24714e-014 Various data Zoom ratio 1.88 Wide-angle, Medium, Telephoto Focal length 9.29 13.30 17.45 F-number 4.12 4.12 4.12 Half-angle (°): 63.94, 56.38, 51.11 Image height 19.00 20.00 21.64 Lens length: 105.60 mm, 99.31 mm, 98.26 mm BF 16.71 19.85 23.00 d10 20.20 8.40 1.84 d22 2.53 4.90 7.27 d24 16.71 19.85 23.00 Zoom lens group data Group starting plane focal length 1 1 -14.46 2 11 22.20 3 23 -64.45 (Numerical Example 4) Unit: mm Surface data Face number rd nd νd 1* 220.275 2.90 1.72916 54.7 2* 32.410 6.15 3 31.175 1.40 1.88300 40.8 4 16.115 9.51 5 -290.660 1.30 1.72916 54.7 6 22.553 3.91 7 -169.571 1.30 1.49700 81.5 8 21.068 0.20 9 21.618 6.82 1.71491 36.9 10 -85.580 (variable) 11 (aperture) ∞ 1.19 12 17.641 1.00 1.98612 16.5 13 13.039 5.84 1.54531 64.0 14 -14.123 1.00 1.90043 37.4 15 21.053 4.10 1.80810 22.8 16 -23.652 (variable) 17 16.079 1.20 2.05090 26.9 18 11.931 11.74 1.49700 81.5 19 -84.810 0.15 20 30.614 1.20 1.95375 32.3 21 11.826 7.43 1.43875 94.7 22 -101.861 (variable) 23* -37.104 1.50 1.88300 40.8 24 -79.002 (variable) Image plane ∞ Aspherical data Front page K = 0.00000e+000 A 4= 1.97191e-005 A 6= 2.99251e-008 A8=-1.74633e-010 A10=3.51937e-013 A12=-3.26372e-016 A14 = 1.26655e-019 2nd side K =-2.47970e+000 A 4= 2.99962e-005 A 6=-9.92794e-009 A8= 8.42560e-010 A10=-4.80444e-012 A12= 1.10882e-014 A14 = -8.16079e-018 Page 23 K = 0.00000e+000 A 4=-3.86203e-005 A 6=-2.01864e-007 A8= 1.20212e-009 A10=-1.31950e-011 A12= 4.25469e-014 Various data Zoom ratio 1.74 Wide-angle, Medium, Telephoto Focal length 10.01 13.27 17.46 F-number 4.12 4.12 4.12 Half-angle (°): 62.23, 56.44, 51.10 Image height 19.00 20.00 21.64 Lens length: 110.09 x 104.20 x 100.83 BF 15.91 15.91 15.91 d10 18.93 8.96 1.51 d16 3.46 3.42 2.08 d22 1.95 6.06 11.49 d24 15.91 15.91 15.91 Zoom lens group data Group starting plane focal length 1 1 -14.76 2 11 36.53 3 17 50.52 4 23 -80.58 (Numerical Example 5) Unit: mm Surface data Face number rd nd νd 1* 224.242 2.90 1.72916 54.7 2* 36.428 6.51 3 33.747 1.40 1.88300 40.8 4 16.495 9.51 5 138.399 1.30 1.72916 54.7 6 19.606 4.29 7 -89.955 1.30 1.49700 81.5 8 23.079 0.20 9 22.235 5.09 1.65320 33.2 10 -83.621 (variable) 11 (aperture) ∞ 1.23 12 18.738 1.00 1.98612 16.5 13 13.892 6.96 1.59061 62.5 14 -12.577 1.00 1.90043 37.4 15 23.254 4.18 1.80810 22.8 16 -23.916 (variable) 17 15.935 1.20 2.05090 26.9 18 12.035 8.85 1.49700 81.5 19 -114.197 0.15 20 30.900 1.20 1.95375 32.3 21 12.473 8.19 1.43875 94.7 22 -29.081 (variable) 23 -16.893 1.00 1.72916 54.7 24 -25.855 (variable) 25* -26.052 1.50 1.77250 49.6 26 -45.917 (variable) Image plane ∞ Aspherical data Front page K = 0.00000e+000 A 4= 1.24565e-005 A 6= 5.68163e-008 A8=-2.01033e-010 A10=3.35836e-013 A12=-2.74725e-016 A14 = 9.91063e-020 2nd side K =-2.52394e+000 A 4= 1.78595e-005 A 6= 2.50128e-008 A8= 6.71921e-010 A10=-3.64716e-012 A12= 7.84554e-015 A14 = -5.37660e-018 Page 25 K = 0.00000e+000 A 4=-4.43508e-005 A 6=-2.47613e-007 A8= 1.39096e-009 A10=-1.53227e-011 A12= 3.30746e-014 Various data Zoom ratio 1.74 Wide-angle, Medium, Telephoto Focal length 10.01 13.19 17.46 F-number 4.12 4.12 4.12 Half-angle (°): 62.21, 56.59, 51.10 Image height 19.00 20.00 21.64 Lens length: 106.74 x 102.63 x 99.55 BF 12.36 12.36 12.36 d10 17.19 8.71 1.26 d16 4.12 4.25 3.59 d22 2.25 2.05 4.03 d24 1.87 6.30 9.35 d26 12.36 12.36 12.36 Zoom lens group data Group starting plane focal length 1 1 -13.96 2 11 34.11 3 17 35.12 4 23 -70.13 5 25 -80.61 The various values ​​in each numerical example are summarized in Table 1 below.

[0078] [Table 1]

[0079] According to each embodiment, a compact and lightweight zoom lens with a wide angle of view and high optical performance across the entire zoom range can be obtained.

[0080] (Imaging device) Next, an example of a digital still camera (imaging device) 10 using the zoom lenses 1a to 1e of each embodiment as the imaging optical system will be described with reference to Figure 11. Figure 11 is a schematic diagram of the imaging device 10 equipped with the zoom lenses 1a to 1e of each embodiment.

[0081] In Figure 11, 113 is the camera body, and 111 is the imaging optical system composed of any of the zoom lenses 1a to 1e described in Examples 1 to 5. 112 is an image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor, which is built into the camera body 113 and receives the optical image formed by the imaging optical system 111 and converts it into photoelectric energy. The camera body 113 may be a so-called single-lens reflex camera with a quick-turn mirror, or a so-called mirrorless camera without a quick-turn mirror.

[0082] By applying the zoom lenses 1a to 1e of each embodiment to an imaging device such as a digital still camera, it is possible to provide an imaging device having a small and lightweight zoom lens with a wide angle of view and high optical performance across the entire zoom range.

[0083] (Imaging system) Furthermore, an imaging system (surveillance camera system) may be configured that includes the zoom lens of each embodiment and a control unit that controls the zoom lens. In this case, the control unit can control the zoom lens so that each lens group moves as described above during zooming and focusing. At this time, the control unit does not need to be integrated with the zoom lens; the control unit may be configured separately from the zoom lens. For example, a configuration may be adopted in which a control unit (control device) located far away from the drive unit that drives each lens of the zoom lens has a transmission unit that sends control signals (commands) for controlling the zoom lens. With such a control unit, the zoom lens can be remotely operated.

[0084] Alternatively, the control unit may be equipped with an operating section such as a controller or buttons for remotely operating the zoom lens, thereby enabling a configuration that controls the zoom lens in response to user input to the operating section. For example, the operating section may include a zoom-in button and a zoom-out button. The control unit can then be configured to send a signal to the zoom lens drive unit so that when the user presses the zoom-in button, the magnification of the zoom lens increases, and when the user presses the zoom-out button, the magnification of the zoom lens decreases.

[0085] Furthermore, the imaging system may have a display unit, such as an LCD panel, that displays information (movement status) related to the zoom of the zoom lens. This information could include, for example, the zoom magnification (zoom status) or the amount of movement of each lens group (movement status). In this case, the user can remotely operate the zoom lens via the control unit while viewing the zoom information displayed on the display unit. The display unit and the control unit may be integrated by, for example, using a touch panel.

[0086] 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 essence. [Explanation of Symbols]

[0087] 1a~1e Zoom Lens L1 First lens group LM intermediate group LR Final Lens Group

Claims

1. A zoom lens comprising a first lens group with negative refractive power, an intermediate group containing one or more lens groups, and a final lens group with negative refractive power, arranged sequentially from the object side to the image side, wherein the spacing between adjacent lens groups changes during zooming. The first lens group includes at least three negative lenses, When TD1 is the thickness of the first lens group on the optical axis, f1 is the focal length of the first lens group, fr is the focal length of the final lens group, mr is the amount of movement of the final lens group when zooming from the wide-angle end to the telephoto end, mf is the amount of movement of the lens group adjacent to the object side of the final lens group when zooming from the wide-angle end to the telephoto end, and fw is the focal length of the zoom lens at the wide-angle end, 0.6<TD1 ２ / (f1×fr)<10.0 -10.0<(mr-mf) / fw<-0.1 A zoom lens characterized by satisfying the following conditional equation.

2. When the back focus of the zoom lens at the wide-angle end is skw, 0.5<TD1 / skw<5.0 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

3. In the aforementioned zoom lens, -12.0<fr / fw<-2.0 A zoom lens according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

4. When POw is the distance from the image plane to the position of the exit pupil at the wide-angle end of the zoom lens, 2.0<POw / fw<10.0 A zoom lens according to any one of claims 1 to 3, characterized in that it satisfies the following conditional expression.

5. When the average focal length of the at least three negative lenses included in the first lens group is fave, -8.0<fave / fw<-2.0 A zoom lens according to any one of claims 1 to 4, characterized in that it satisfies the following conditional expression.

6. The zoom lens according to any one of claims 1 to 5, characterized in that the final lens group consists of a single lens with negative refractive power.

7. When R1 is the radius of curvature of the object-side lens surface of the lens positioned furthest towards the image in the final lens group, and R2 is the radius of curvature of the image-side lens surface of the lens positioned furthest towards the image in the final lens group, 1.0<(R2+R1) / (R2-R1)<10.0 A zoom lens according to any one of claims 1 to 6, characterized in that it satisfies the following conditional expression.

8. When the focal length of the zoom lens at the telephoto end is ft, -3.0<ft / f1<-0.5 A zoom lens according to any one of claims 1 to 7, characterized in that it satisfies the following conditional expression.

9. When the thickness of the final lens group along the optical axis is TDr, 0.05<TDr / fw<0.50 A zoom lens according to any one of claims 1 to 8, characterized in that it satisfies the following conditional expression.

10. When the total lens length of the zoom lens at the telephoto end is TTDt, 2.0<TTDt / ft<10.0 A zoom lens according to any one of claims 1 to 9, characterized in that it satisfies the following conditional expression.

11. The zoom lens according to any one of claims 1 to 10, characterized in that the at least three negative lenses are arranged in a continuous sequence from the object side to the image side.

12. The zoom lens according to any one of claims 1 to 11, characterized in that the final lens group includes an aspherical element.

13. The zoom lens according to any one of claims 1 to 12, characterized in that it comprises four lens groups with negative, positive, positive, and negative refractive powers, arranged in order from the object side to the image side.

14. The zoom lens according to any one of claims 1 to 12, characterized in that it comprises three lens groups with negative, positive, and negative refractive powers, arranged in order from the object side to the image side.

15. The zoom lens according to any one of claims 1 to 12, characterized in that it comprises five lens groups with negative, positive, positive, negative, and negative refractive powers, arranged in order from the object side to the image side.

16. An imaging device characterized by having a zoom lens according to any one of claims 1 to 15 and an image sensor that receives an image formed by the zoom lens.

17. An imaging system characterized by comprising a zoom lens according to any one of claims 1 to 15, and a control unit that controls the zoom lens during zooming.

18. The imaging system according to claim 17, characterized in that the control unit is configured separately from the zoom lens and has a transmitting unit that transmits control signals for controlling the zoom lens.

19. The imaging system according to claim 17 or 18, characterized in that the control unit is configured separately from the zoom lens and has an operating section for operating the zoom lens.

20. The imaging system according to any one of claims 17 to 19, characterized in that it has a display unit that displays information regarding the zoom of the zoom lens.

Images