JP2018063286A - Zoom lens and imaging device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a zoom lens that has a wide angle of view and a high zoom ratio even through the entire system is compact, and has high optical performance over the entire zoom range.SOLUTION: A zoom lens has a first lens group having a negative refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power arranged in order from an object side to an image side; in zooming, the first lens group is immobile, the second lens group and third lens group move, and the interval between the adjacent lens groups is changed. The first lens group has two or more negative lenses. The focal distance f1 of the first lens group, the focal distance fw of the entire system at a wide angle end, the focal distance ft of the entire system at a telephoto end, the interval D12w on the optical axis between the first lens group and second lens group at the wide angle end, and the back focus BF at the wide angle end are appropriately set, respectively.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a zoom lens, and is particularly suitable as an imaging optical system used in an imaging apparatus such as a surveillance camera, a digital camera, a video camera, and a broadcast camera.

  2. Description of the Related Art In recent years, an imaging optical system used in an imaging device using an imaging device has high optical performance that can cope with an increase in the number of pixels (high definition) of the imaging device, and can capture images at various magnifications and has a wide angle of view. There is a demand for a zoom lens. For example, from the viewpoint of high image quality, the shift from SD (Standard Definition) image quality to megapixel, full HD (High Definition), and 4K image quality is accelerating. For this reason, the imaging optical system used in the imaging apparatus is required to be a zoom lens having high optical performance that can handle these high-definition imaging elements.

  In addition, an imaging optical system for a surveillance camera is desired to have a high zoom ratio and a high degree of freedom in monitoring while facilitating wide-area imaging (wide angle of view) with a single camera. Has been. Furthermore, there is a demand for the entire system to be miniaturized from the viewpoints of indoor and outdoor installation and difficulty of conspicuousness. As a zoom lens satisfying these demands, there is known a negative lead type zoom lens in which a lens group having a negative refractive power is disposed closest to the object side (positioned closest to the object side) (Patent Documents 1 to 3). .

  Patent Document 1 includes first to fourth lens groups having negative, positive, negative, and positive refractive power in order from the object side to the image side, and each lens group moves during zooming, and adjacent lenses. A zoom lens with varying group spacing is disclosed. Patent Documents 2 and 3 include first to fourth lens groups having negative, negative, positive, and positive refractive powers in order from the object side to the image side, and the second lens group and the third lens group are used for zooming. A zoom lens that moves and changes the interval between adjacent lens groups is disclosed.

JP 2013-250338 A JP 2009-25801 A JP 2014-219543 A

  In order to obtain high optical performance while reducing the overall system size, wide angle of view, and high zoom ratio in the negative lead type zoom lens, the refractive power of each lens group, the lens configuration of each lens group, etc. It is important to set it properly.

  In a negative lead type zoom lens in which the first lens unit moves during zooming from the wide-angle end to the telephoto end, the first lens unit becomes larger in order to further increase the field angle. Further, when trying to increase the zoom ratio, the amount of movement of the first lens group increases, and the entire system becomes larger. In a negative lead type zoom lens in which the first lens unit is not moved during zooming, it is necessary to select the zoom lens unit and to appropriately set the movement amount of the zoom lens unit during zooming. Otherwise, it becomes difficult to reduce the size of the entire system while ensuring a predetermined zoom ratio (high zoom ratio).

  An object of the present invention is to provide a zoom lens having a high optical performance over a whole zoom range with a wide angle of view and a high zoom ratio while the entire system is small.

The zoom lens of the present invention includes a first lens group having a negative refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side to the image side. ,
During zooming, the first lens group is stationary, the second lens group and the third lens group move, and the distance between adjacent lens groups changes, and the first lens group is 2 Have more than one negative lens,
The focal length of the first lens group is f1, the focal length of the entire system at the wide angle end is fw, the focal length of the entire system at the telephoto end is ft, and the optical axis of the first lens group and the second lens group at the wide angle end Is set to D12w and the back focus at the wide angle end is set to BFw.
0.70 <| f1 / √ (fw × ft) | <2.70
0.60 <D12w / BFw <5.30
It satisfies the following conditional expression.

  According to the present invention, it is possible to obtain a zoom lens having high optical performance over the entire zoom range with a wide angle of view and a high zoom ratio while the entire system is small.

FIG. 5 is a diagram of a lens cross section and a movement locus at the wide angle end according to the first embodiment. (A), (B), (C) Various aberration diagrams at the wide-angle end, zoom intermediate position, and telephoto end of Example 1. FIG. 10 is a diagram of a lens cross section and a movement locus at the wide angle end according to the second embodiment. (A), (B), (C) Various aberration diagrams at the wide-angle end, zoom intermediate position, and telephoto end of Example 2. FIG. 12 is a diagram of a lens cross section and a movement locus at the wide angle end according to the third embodiment. (A), (B), (C) Various aberration diagrams at the wide-angle end, zoom intermediate position, and telephoto end of Example 3. FIG. 12 is a diagram of a lens cross section and a movement locus at the wide angle end according to the fourth embodiment. (A), (B), (C) Various aberration diagrams at the wide-angle end, zoom intermediate position, and telephoto end of Example 4. FIG. 12 is a diagram of a lens cross section and a movement locus at the wide angle end according to the fifth embodiment. (A), (B), (C) Various aberration diagrams at the wide-angle end, zoom intermediate position, and telephoto end of Example 5. FIG. 12 is a diagram of a lens cross section and a movement locus at the wide angle end according to the sixth embodiment. (A), (B), (C) Various aberration diagrams at the wide-angle end, zoom intermediate position, and telephoto end of Example 6. Diagram showing symbols on the lens cross section at the wide-angle end and the telephoto end (A), (B) The example of the Example and use example with the surveillance camera of this invention

  Hereinafter, the zoom lens of the present invention and an image pickup apparatus having the same will be described. The zoom lens of the present invention includes a first lens group having a negative refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side to the image side. During zooming, the first lens group does not move, the second lens group and the third lens group move, and the interval between adjacent lens groups changes.

  FIG. 1 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to Embodiment 1 of the present invention. 2A, 2B, and 2C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end (long focal length end) of the zoom lens according to the first exemplary embodiment of the present invention. Example 1 is a zoom lens having a zoom ratio of 4.86 and an F number of about 1.86 to 4.28.

  FIG. 3 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 2 of the present invention. FIGS. 4A, 4B, and 4C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to the second embodiment of the present invention. The second embodiment is a zoom lens having a zoom ratio of 3.90 and an F number of about 1.84 to 3.80.

  FIG. 5 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 3 of the present invention. FIGS. 6A, 6B, and 6C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to the third exemplary embodiment of the present invention. Example 3 is a zoom lens having a zoom ratio of 2.89 and an F number of about 1.67 to 3.00.

  FIG. 7 is a lens cross-sectional view at the wide-angle end of the zoom lens according to a fourth exemplary embodiment of the present invention. FIGS. 8A, 8B, and 8C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to the fourth exemplary embodiment of the present invention. Example 4 is a zoom lens having a zoom ratio of 3.90 and an F number of about 1.86 to 4.63.

  FIG. 9 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 5 of the present invention. FIGS. 10A, 10B, and 10C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to the fifth exemplary embodiment of the present invention. Example 5 is a zoom lens having a zoom ratio of 3.94 and an F number of about 1.86 to 4.28.

  FIG. 11 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 6 of the present invention. 12A, 12B, and 12C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 6 of the present invention. Example 6 is a zoom lens having a zoom ratio of 5.90 and an F number of about 1.82 to 5.05.

  FIGS. 13A and 13B are explanatory views of the positional relationship of each lens group at the wide-angle end and the telephoto end of the zoom lens of the present invention. 14A and 14B are schematic views of an imaging apparatus such as a surveillance camera provided with the zoom lens of the present invention.

  The zoom lens of each embodiment is an imaging optical system used in an imaging apparatus. In the lens cross-sectional view, the left side is the object side (front), and the right side is the image side (rear). The zoom lens of each embodiment may be used in a projection optical system of an optical device such as a projector. In this case, the left side is a screen and the right side is a projected image. In the lens cross-sectional view, SP is an F number determining member (hereinafter also referred to as “aperture stop”) that functions as an aperture stop that determines (limits) an open F number (Fno) light beam.

  G is an optical block corresponding to an optical filter, a face plate, a quartz low-pass filter, an infrared cut filter, or the like. IP is an image plane, and when used as a photographing optical system of a video camera or a digital still camera, an imaging plane of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is placed.

  Solid arrows indicate the movement trajectory of each lens unit during zooming from the wide-angle end to the telephoto end. In the second lens unit L2, a solid arrow 2a indicates a movement locus during zooming from the wide-angle end to the telephoto end when focusing at infinity. A broken-line arrow 2b indicates a movement locus during zooming from the wide-angle end to the telephoto end when focusing on a short distance. An arrow F indicates a moving direction at the time of focusing from infinity to a short distance.

  The second lens unit L2 corresponds to a compensator lens unit that corrects image plane fluctuations accompanying zooming. The wide-angle end and the telephoto end are zoom positions when the zooming lens groups are positioned at both ends of the range in which the zoom lens group can move on the optical axis.

  The zoom lenses of Examples 1, 2, 3, and 5 are arranged in order from the object side to the image side, the first lens unit L1 having a negative refractive power, the second lens unit L2 having a negative refractive power, and a positive refraction. The third lens unit L3 has a strong power and the fourth lens unit L4 has a negative refractive power. When zooming from the wide-angle end to the telephoto end, each lens unit moves as indicated by an arrow. The zoom lens of Example 4 includes a first lens unit L1 having a negative refractive power, a second lens unit L2 having a negative refractive power, and a third lens unit having a positive refractive power, which are arranged in order from the object side to the image side. L3. When zooming from the wide-angle end to the telephoto end, each lens unit moves as indicated by an arrow.

  The zoom lens of Embodiment 6 includes a first lens unit L1 having a negative refractive power, a second lens unit L2 having a negative refractive power, and a third lens unit having a positive refractive power, which are arranged in order from the object side to the image side. L3 includes a fourth lens unit L4 having a positive refractive power and a fifth lens unit L5 having a negative refractive power. When zooming from the wide-angle end to the telephoto end, each lens unit moves as indicated by an arrow.

  The aperture stop SP is disposed on the object side of the third lens unit L3 and is moved integrally with the third lens unit L3 during zooming. However, the aperture stop SP may be moved independently. This is preferable because the degree of freedom for cutting flare rays is increased. In the spherical aberration diagram and the lateral chromatic aberration diagram in the aberration diagrams, the solid line d indicates the d line (587.56 nm), and the broken line g indicates the g line (435.84 nm). In the astigmatism diagram, the dotted line ΔM represents the meridional image plane at the d line, and the solid line ΔS represents the sagittal image plane at the d line. In the distortion aberration, the d line is displayed. Fno is an F number, and ω is a half angle of view (degrees).

  The zoom lens according to the present invention has a wide angle of view and a high zoom ratio while having a small overall system, and has high optical performance over the entire zoom range. The zoom type of the zoom lens of the present invention has a negative lead type configuration preceded by a lens unit having a negative refractive power.

  In a conventional negative lead type zoom lens, a first lens group having a negative refractive power and a second lens group having a positive refractive power are arranged in order from the object side to the image side. In many cases, the first lens unit is moved during zooming. In this lens configuration, the effective diameter of the first lens group becomes large when a wide angle of view is achieved, so that the driving load when moving the first lens group becomes large. This increases the size of the drive motor, making it difficult to reduce the size of the lens barrel. Furthermore, quick zooming and focusing become difficult.

  On the other hand, in the present invention, the following lens unit is disposed on the image side of the first lens unit L1 having a negative refractive power that does not move during zooming. A lens group (compensator lens group) for correcting image plane fluctuations due to zooming and a second lens group L2 having a negative refractive power that serves as a focus lens group are arranged.

  In this case, the second lens unit L2, which is a moving lens unit, is reduced in size by making the first lens unit L1 whose effective diameter tends to be large when zooming in to be stationary during zooming. This also reduces the driving load due to zooming and focusing, facilitating the miniaturization of the motor and the lens barrel. Further, the first lens unit L1 is configured to have two or more negative lenses. This relaxes the curvature of each lens surface while maintaining a strong negative refractive power, suppresses the occurrence of spherical aberration, obtains high optical performance, and facilitates widening the angle of view.

In each embodiment, the focal length of the first lens unit L1 is f1. Let fw be the focal length of the entire system at the wide-angle end. Let ft be the focal length of the entire system at the telephoto end. The distance on the optical axis between the first lens unit L1 and the second lens unit L2 at the wide-angle end is D12w. The back focus at the wide angle end is BFw. At this time,
0.70 <| f1 / √ (fw × ft) | <2.70 (1)
0.60 <D12w / BFw <5.30 (2)
The following conditional expression is satisfied.

  Next, numerical values relating to the positional relationship between the lens groups at the wide-angle end and the telephoto end and the amount of movement during zooming in the zoom lens of the present invention will be described with reference to FIG. In FIG. 13, D12w represents a distance on the optical axis from the most image side lens surface of the first lens unit L1 to the most object side lens surface of the second lens unit L2 at the wide-angle end. M3wt represents the amount of movement of the third lens unit L3 from the wide-angle end to the telephoto end, and TL represents the total lens length (air conversion distance from the first lens surface to the image plane).

  In zooming from the wide-angle end to the telephoto end, the third lens unit L3, which is a variable power lens unit, moves monotonously toward the object side, and the second lens unit L2 moves along a convex locus toward the image side. At this time, the third lens unit L3 is arranged such that the position of the surface closest to the object side of the third lens unit L3 is closer to the object side than the position of the lens surface closest to the object side of the second lens unit L2 at the wide angle end. It is moved. In this way, the third lens unit L3, which is the main variable magnification lens unit, is largely moved toward the object side so as to overlap the movement locus of the second lens unit L2, which is the compensator lens unit. A high zoom ratio is achieved while downsizing.

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (1) sets the relationship between the focal length of the first lens unit L1 and the product of the focal length of the entire system at the wide-angle end and the focal length of the entire system at the telephoto end. The first lens unit L1 has a relatively strong negative refractive power for widening the angle of view. If the negative focal length of the first lens unit L1 is increased beyond the upper limit of the conditional expression (1) (the absolute value of the negative focal length is increased), it is difficult to obtain the effect of widening the angle of view. .

  If the lower limit of conditional expression (1) is exceeded and the negative focal length of the first lens unit L1 becomes shorter (the absolute value of the negative focal length becomes smaller), spherical aberration increases at the telephoto end, which is not preferable.

  Conditional expression (2) defines the ratio of the distance between the first lens unit L1 and the second lens unit L2 at the wide-angle end (distance on the optical axis) and the back focus. In order to reduce the size of the entire system and increase the zoom ratio, it is necessary to appropriately set the positional relationship between the first lens unit L1 and the second lens unit L2 at the wide-angle end. Note that the back focus BFw is the distance from the lens final surface to the image plane at the wide-angle end when converted to air (the length of the glass block material G is the length converted to air).

  If the lower limit of the conditional expression (2) is exceeded and the distance between the first lens unit L1 and the second lens unit L2 is shortened, the movement locus of the second lens unit L2, which is a compensator lens unit, is limited. As a result, it is difficult to ensure a sufficient movement locus of the second lens unit L2 due to zooming, and it is difficult to achieve a high zoom ratio. If the upper limit of conditional expression (2) is exceeded and the distance between the first lens unit L1 and the second lens unit L2 becomes longer, the first lens unit L1 having a larger beam diameter comes to be positioned on the object side, and the lens is effective. The diameter increases, making it difficult to reduce the size of the entire system.

  As described above, according to the present invention, it is possible to obtain a zoom lens having an imaging half angle of view of 60 degrees or more, a zoom ratio of 2.5, and compatible with an imaging device having full HD or 4K pixels.

  In each embodiment, it is preferable to satisfy one or more of the following conditional expressions. The focal length of the first lens unit L1 is f1, and the focal length of the second lens unit L2 is f2. The amount of movement of the third lens unit L3 during zooming from the wide-angle end to the telephoto end is M3wt. Here, the sign of the moving amount of the lens group is a result of moving by zooming from the wide-angle end to the telephoto end, so that when the position is located on the object side at the telephoto end compared to the wide-angle end, it is negative, when it is located on the image side Positive.

  The distance (lens group length) from the most object side lens surface of the first lens unit L1 to the most image side lens surface of the first lens unit L1 is TL1G. Let the focal length of the third lens unit L3 be f3. The lateral magnification of the third lens unit L3 at the wide angle end is β3w, and the lateral magnification of the third lens unit L3 at the telephoto end is β3t. Let TL be the distance from the lens surface closest to the object side to the image plane (lens total length). The back focus at the wide angle end is BFw.

At this time, it is preferable to satisfy one or more of the following conditional expressions.
0.10 <f1 / f2 <1.00 (3)
0.50 <| M3wt | / f3 <3.00 (4)
3.00 <TL1G / fw <6.00 (5)
−3.20 <f2 / f3 <−1.20 (6)
0.30 <f3 / ft <1.00 (7)
5.0 <TL / BFw <35.0 (8)

When the zoom lens of the present invention is applied to an image pickup apparatus having an image pickup element, it is preferable that the following conditional expression is satisfied. Let the imaging half angle of view at the wide angle end be ωw. Let the imaging half angle of view at the telephoto end be ωt. The lateral magnification of the third lens unit L3 at the wide angle end is β3w. The lateral magnification of the third lens unit L3 at the telephoto end is β3t. At this time,
1.50 <(tan ωw / tan ωt) / (β3t / β3w) <7.00 (9)
It is good to satisfy the following conditional expression.

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (3) is a second moving state for correcting and focusing the image plane variation accompanying the zooming with respect to the focal length of the first lens unit L1 having a relatively strong negative refractive power for widening the angle of view. The relationship between the focal lengths of the lens unit L2 is defined. If the upper limit of conditional expression (3) is exceeded and the negative focal length of the first lens unit L1 increases (the absolute value of the negative focal length increases), the effect of widening the angle of view cannot be obtained sufficiently. The effective lens diameter becomes large, and it is difficult to reduce the size of the entire system.

  Further, when the negative focal length of the second lens unit L2 becomes shorter than the upper limit of the conditional expression (3) (when the absolute value of the negative focal length becomes smaller), the curvature of field increases. If the lower limit of conditional expression (3) is exceeded and the focal length of the first lens unit L1 becomes shorter, spherical aberration will increase at the telephoto end. If the negative focal length of the second lens unit L2 is increased beyond the lower limit of conditional expression (3), the amount of movement of the second lens unit L2 during zooming from the wide-angle end to the telephoto end increases. It becomes difficult to downsize the system.

  Conditional expression (4) appropriately sets the relationship between the amount of movement in zooming from the wide-angle end to the telephoto end of the third lens unit L3, which is the main variable magnification lens unit, and the focal length of the third lens unit L3. is there. When the focal length of the third lens unit L3 with respect to the movement amount of the third lens unit L3 exceeds the upper limit of the conditional expression (4), field curvature and chromatic aberration increase in the entire zoom range, and correction of these various aberrations is performed. Becomes difficult. When the focal length of the third lens unit L3 with respect to the movement amount of the third lens unit L3 exceeds the lower limit of the conditional expression (4), the positive refractive power as the variable power lens unit becomes weak, and thus a high zoom ratio. It becomes difficult.

  Conditional expression (5) defines the lens group length of the first lens unit L1. Conditional expression (5) is for satisfactorily correcting aberrations while widening the angle of view. If the upper limit of conditional expression (5) is exceeded and the lens group length of the first lens group L1 becomes longer, it becomes difficult to reduce the size of the entire system. When the lens group length of the first lens unit L1 becomes shorter than the lower limit of the conditional expression (5), it is necessary to shorten the negative focal length in order to secure a predetermined amount of negative refractive power of the first lens unit L1. And spherical aberration increases at the telephoto end.

  Conditional expression (6) sets the relationship between the focal length of the third lens unit L3, which is the main variable magnification lens unit, and the focal length of the second lens unit L2, which requires a negative refractive power as the focus lens unit. ing. When the upper limit of conditional expression (6) is exceeded and the negative focal length of the second lens unit L2 becomes shorter, the curvature of field increases. Further, if the focal length of the third lens unit L3 responsible for zooming exceeds the upper limit of the conditional expression (6), the amount of movement of the third lens unit L3 during zooming from the wide-angle end to the telephoto end increases. However, downsizing of the entire system becomes difficult.

  If the negative focal length of the second lens unit L2 exceeds the lower limit of conditional expression (6), the amount of movement of the second lens unit L2 during zooming from the wide-angle end to the telephoto end increases, Miniaturization becomes difficult. If the focal length of the third lens unit L3 is shortened beyond the lower limit of conditional expression (6), field curvature and chromatic aberration increase in the entire zoom range, making it difficult to correct these various aberrations.

  Conditional expression (7) sets a high zoom ratio and downsizing the entire system by appropriately setting the relationship between the focal length of the third lens unit L3 responsible for zooming and the focal length of the entire system at the telephoto end. This is intended to obtain good optical performance. When the upper limit of conditional expression (7) is exceeded and the focal length of the third lens unit L3 responsible for zooming becomes too long, the amount of movement of the third lens unit L3 during zooming from the wide-angle end to the telephoto end increases. This makes it difficult to downsize the entire system. If the lower limit of conditional expression (7) is exceeded and the focal length of the third lens unit L3 is shortened, field curvature and chromatic aberration will increase over the entire zoom range, making it difficult to correct these aberrations.

  Conditional expression (8) defines the ratio of the back focal length at the wide-angle end to the total lens length. If the upper limit of the conditional expression (8) is exceeded and the back focus becomes too short, the space for arranging a filter such as a low-pass filter between the final lens surface and the image surface is reduced, which is not good. If the lower limit of the conditional expression (8) is exceeded and the back focus becomes too long, it becomes difficult to secure a sufficient space for moving each lens unit in zooming, and it is difficult to reduce the size of the entire system.

  Conditional expression (9) defines the relationship of the change of the imaging field angle in the zooming of the third lens unit L3 which is the main zooming lens unit. The imaging half field angle ωw and the imaging half field angle ωt both indicate the imageable range including distortion. Exceeding the upper limit of conditional expression (9) is not preferable because distortion increases at the wide-angle end. If the lower limit of conditional expression (9) is exceeded, it will be difficult to obtain the required change in the angle of view (higher zoom ratio) due to zooming.

More preferably, the numerical ranges of the conditional expressions (1) to (9) are set as follows.
1.00 <| f1 / √ (fw × ft) | <2.40 (1a)
0.90 <D12w / BFw <5.00 (2a)
0.25 <f1 / f2 <0.95 (3a)
0.80 <| M3wt | / f3 <2.50 (4a)
3.40 <TL1G / fw <5.50 (5a)
−3.10 <f2 / f3 <−1.50 (6a)
0.40 <f3 / ft <0.95 (7a)
7.0 <TL / BFw <30.0 (8a)
2.00 <(tan ωw / tan ωt) / (β3t / β3w) <6.60 (9a)

More preferably, the numerical ranges of the conditional expressions (1a) to (9a) are desirably in the following ranges.
1.50 <| f1 / √ (fw × ft) | <1.90 (1b)
1.20 <D12w / BFw <4.70 (2b)
0.40 <f1 / f2 <0.90 (3b)
1.10 <| M3wt | / f3 <2.00 (4b)
3.80 <TL1G / fw <5.00 (5b)
-2.9 <f2 / f3 <-1.80 (6b)
0.50 <f3 / ft <0.90 (7b)
9.0 <TL / BFw <26.0 (8b)
2.30 <(tan ωw / tan ωt) / (β3t / β3w) <6.30 (9b)

  In each embodiment, the second lens unit L2 includes one lens or one cemented lens obtained by cementing a plurality of lenses, and the lens surface closest to the object side of the second lens unit L2 has a concave shape. The second lens unit L2 moves during focusing. During zooming from the wide-angle end to the telephoto end, the second lens unit L2 moves to the object side after moving to the image side, and the third lens unit L3 moves to the object side. In Examples 1, 2, 3, and 5, the fourth lens unit L4 having a negative refractive power is further provided on the image side of the third lens unit L3, and the fourth lens unit L4 moves during zooming.

  In Example 6, a fourth lens unit L4 having a positive refractive power disposed on the image side of the third lens unit L3 and a first lens unit having a negative refractive power disposed adjacent to the image side of the fourth lens unit L4. The fourth lens unit L4 and the fifth lens unit L5 move during zooming.

  Hereinafter, the lens configuration of each lens group in each example will be described. Hereinafter, the lens configurations of the lens groups are arranged in order from the object side to the image side unless otherwise specified.

Example 1
The first lens unit L1 includes a meniscus negative lens G11 having a convex surface on the object side, a negative meniscus negative lens G12 having a convex surface on the object side, a negative lens G13 having a biconcave shape, and a positive meniscus lens G14 having a convex surface on the object side. Yes. By making the negative lens G11 into a meniscus shape, the effective lens diameter is made as small as possible. Further, in order to reduce the occurrence of various aberrations when the negative refractive power of the first lens unit L1 having negative refractive power is increased for widening the angle of view, the first lens unit L1 has a plurality of negative lenses. I have to.

  The second lens unit L2 includes a meniscus positive lens G21 having a convex surface on the image side and a negative meniscus lens G22 having a convex surface on the image side. The positive lens G21 and the negative lens G22 are composed of bonded cemented lenses, and chromatic aberration is favorably corrected by increasing the difference in Abbe number of the materials of both lenses.

  The third lens unit L3 includes a biconvex positive lens G31, a biconvex positive lens G32, a biconcave negative lens G33, and a biconvex positive lens G34. The positive lens G32 and the negative lens G33 are composed of bonded cemented lenses, and chromatic aberration is favorably corrected by increasing the difference in Abbe number of the materials of both lenses. Further, both surfaces of the positive lens G31 and the positive lens G34 are aspherical.

  This appropriately arranges an aspherical surface in the third lens unit L3 in which the on-axis luminous flux that determines the F number (Fno) spreads, and corrects spherical aberration that is likely to occur when the aperture is increased. The fourth lens unit L4 includes a meniscus positive lens G41 having a convex surface on the image side and a negative meniscus lens G42 having a convex surface on the image side.

(Example 2)
The lens configurations of the first lens unit L1 to the fourth lens unit L4 in Example 2 are the same as those in Example 1. Here, the same lens configuration means that the arrangement and lens shape of each lens are the same.

(Example 3)
In Example 3, the lens configurations of the first lens unit L1 and the third lens unit L3 are the same as those in Example 1. The second lens unit L2 includes a negative meniscus lens G21 having a convex surface on the image side. The fourth lens unit L4 includes a meniscus positive lens G41 having a convex surface on the image side and a biconcave negative lens G42.

Example 4
In Example 4, the lens configuration of the second lens unit L2 is the same as that of Example 1. The first lens unit L1 includes a negative meniscus lens G11 having a convex surface on the object side, a negative meniscus lens G12 having a convex surface on the object side, a negative meniscus lens G13 having a convex surface on the object side, and a positive meniscus lens G14 having a convex surface on the object side. It consists of. By making the negative lens G11 into a meniscus shape, the effective lens diameter is made as small as possible. Further, in order to reduce the occurrence of various aberrations when the negative refractive power of the first lens unit L1 having negative refractive power is increased for widening the angle of view, the first lens unit L1 has a plurality of negative lenses. I have to.

  The third lens unit L3 includes a biconvex positive lens G31, a biconvex positive lens G32, a biconcave negative lens G33, a meniscus positive lens G34 having a convex surface on the object side, and a meniscus positive on the object side having a convex surface. It consists of a lens G35. The positive lens G32 and the negative lens G33 are composed of bonded cemented lenses, and chromatic aberration is favorably corrected by increasing the difference in Abbe number of the materials of both lenses.

  Further, both surfaces of the positive lens G31 and the positive lens G34 are aspherical. This appropriately arranges an aspherical surface in the third lens unit L3 in which the on-axis light beam that determines the F number spreads, and corrects spherical aberrations that are likely to occur when the aperture is increased.

(Example 5)
The lens configurations of the first lens unit L1 and the second lens unit L2 in Example 5 are the same as those in Example 1. The third lens unit L3 includes a meniscus positive lens G31 having a convex surface on the object side, a biconvex positive lens G32, a biconcave negative lens G33, and a biconvex positive lens G34. The positive lens G32 and the negative lens G33 are composed of bonded cemented lenses, and chromatic aberration is favorably corrected by increasing the difference in Abbe number of the materials of both lenses. Further, both surfaces of the positive lens G31 and the positive lens G34 are aspherical.

  This appropriately arranges an aspherical surface in the third lens unit L3 in which the on-axis light beam that determines the F number spreads, and corrects spherical aberrations that are likely to occur when the aperture is increased. The fourth lens unit L4 includes a meniscus negative lens G41 having a convex surface on the image side.

(Example 6)
The lens configurations of the first lens unit L1 and the second lens unit L2 in Example 6 are the same as those in Example 1. The third lens unit L3 includes a biconvex positive lens G31, a biconvex positive lens G32, a biconcave negative lens G33, and a meniscus positive lens G34 having a convex surface on the object side. The positive lens G32 and the negative lens G33 are composed of bonded cemented lenses, and chromatic aberration is favorably corrected by increasing the difference in Abbe number of both lens materials. Further, both surfaces of the positive lens G31 and the positive lens G34 are aspherical.

  This appropriately arranges an aspherical surface in the third lens unit L3 in which the on-axis light beam that determines the F number spreads, and corrects spherical aberrations that are likely to occur when the aperture is increased. The fourth lens unit L4 includes a meniscus positive lens G41 having a convex surface on the object side. The fifth lens unit L5 includes a negative meniscus lens G51 having a convex surface on the image side.

  Next, an embodiment of an image pickup apparatus (surveillance camera) using the zoom lens of the present invention as an image pickup optical system will be described with reference to FIGS.

  In FIG. 14A, reference numeral 10 denotes a monitoring camera. Reference numeral 11 denotes a surveillance camera body, and 16 denotes an imaging optical system formed by any one of the zoom lenses according to the first to sixth embodiments. Reference numeral 12 denotes an image pickup device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor that receives a subject image formed by the image pickup optical system 16 and is built in the surveillance camera body 11. A memory unit 13 records information corresponding to the subject image photoelectrically converted by the image sensor 12.

  Reference numeral 14 denotes a network cable for transferring a subject image photoelectrically converted by the image sensor 12. FIG. 14B shows an example when the imaging apparatus 10 is used with a dome-shaped cover 15 attached to the ceiling.

  The imaging apparatus according to the present invention is not limited to a surveillance camera, and can be used in a video camera, a digital camera, or the like.

  As described above, according to each embodiment, it is possible to obtain a zoom lens having an ultra-wide angle of view and a high zoom ratio while having a small size, and an imaging apparatus having the same.

In each embodiment, the following configuration may be adopted.
-It is not limited to the lens shape and the number of lenses shown in each embodiment, and should be changed as appropriate.
-Move some lenses and lens groups so that they have a component in a direction perpendicular to the optical axis, thereby correcting image blur due to vibration such as camera shake.
-Correct distortion and chromatic aberration with electrical correction means.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments and optical specifications (view angle and FNo), and various modifications can be made within the scope of the gist.

  Next, the numerical data of the Example corresponding to each Example are shown. In the numerical data of each embodiment, the surface number i indicates the order of the optical surfaces counted from the object side. ri is the radius of curvature of the i-th optical surface. di is the i-th and i + 1-th surface spacing. ndi and νdi respectively indicate the refractive index and Abbe number of the material of the optical member with respect to the d line. The two surfaces closest to the image side are glass materials such as face plates. * Means an aspherical surface.

  The back focus (BF) is an air conversion distance from the last lens surface to the paraxial image plane. The total lens length is defined as a value obtained by adding back focus (BF) to the distance from the front lens surface to the final lens surface. Also, when K is the eccentricity, A4, A6, A8, and A10 are aspheric coefficients, and the displacement in the optical axis direction at the position of the height H from the optical axis is X with respect to the surface vertex, the aspheric shape is ,

Is displayed. Where R is the radius of curvature. Further, for example, the display of “e-Z” means “10 ^−Z ”. Table 1 shows the correspondence with the above-described conditional expressions in each example. f is a focal length (d line), Fno is an F number, and a half angle of view (ω) is a numerical value relating to a shootable angle of view in consideration of the amount of distortion.

[Numeric data 1]
Unit mm

Surface data surface number rd nd νd
1 49.075 1.70 1.69680 55.5
2 29.005 4.19
3 41.644 1.30 1.69680 55.5
4 16.380 10.08
5 -50.092 0.90 1.59522 67.7
6 44.046 1.80
7 32.719 2.57 1.95906 17.5
8 69.216 (variable)
9 -13.005 0.98 1.89286 20.4
10 -11.074 0.45 1.69680 55.5
11 -60.576 (variable)
12 (Aperture) ∞ 0.40
13 * 11.412 3.99 1.58313 59.4
14 * -57.464 0.74
15 14.515 5.00 1.49700 81.5
16 -13.184 0.45 1.90366 31.3
17 16.567 1.17
18 * 9.091 4.15 1.49710 81.6
19 * -32.945 (variable)
20 -116.812 2.64 1.95906 17.5
21 -27.431 3.47
22 -15.752 0.60 1.74950 35.3
23 -287.447 (variable)
24 ∞ 2.00 1.54400 60.0
Image plane ∞

Aspherical data 13th surface
K = 0.00000e + 000 A 4 = -4.61684e-005 A 6 = 3.50702e-007 A 8 = -3.35096e-009 A10 = -4.83765e-011

14th page
K = 0.00000e + 000 A 4 = -2.05089e-005 A 6 = 1.13431e-006 A 8 = -1.50419e-008 A10 = 1.60944e-011

18th page
K = 0.00000e + 000 A 4 = -2.33042e-004 A 6 = 4.11749e-006 A 8 = -3.74200e-008 A10 = 5.65495e-010

19th page
K = 0.00000e + 000 A 4 = 2.55599e-004 A 6 = 4.35425e-006 A 8 = 6.13415e-009 A10 = 1.02214e-009

Various data Zoom ratio 4.86

Focal length 5.21 11.47 25.33
F number 1.86 2.86 4.28
Half angle of view (degrees) 46.53 25.61 12.25
Image height 5.50 5.50 5.50
Total lens length 82.30 82.30 82.30
BF 5.25 16.97 30.19

d 8 17.02 15.52 2.15
d11 11.06 2.56 0.93
d19 2.41 0.69 2.46
d23 1.48 13.19 26.41

Zoom lens group data group Start surface Focal length
1 1 -20.90
2 9 -26.14
3 12 13.66
4 20 -70.99

[Numeric data 2]
Unit mm

Surface data surface number rd nd νd
1 43.244 1.30 1.69680 55.5
2 22.587 5.69
3 56.518 1.10 1.59522 67.7
4 14.979 8.11
5 -37.756 0.80 1.59522 67.7
6 84.740 0.81
7 34.852 2.90 1.95906 17.5
8 90.794 (variable)
9 -12.086 0.90 1.89286 20.4
10 -10.503 0.58 1.69680 55.5
11 -51.261 (variable)
12 (Aperture) ∞ 0.40
13 * 11.598 3.80 1.58313 59.4
14 * -56.865 0.75
15 14.511 5.00 1.49700 81.5
16 -12.803 0.45 1.90366 31.3
17 19.806 1.02
18 * 9.225 4.24 1.49710 81.6
19 * -27.772 (variable)
20 -99.993 2.80 1.95906 17.5
21 -26.574 3.16
22 -15.375 0.60 1.74950 35.3
23 -288.945 (variable)
24 ∞ 2.00 1.54400 60.0
Image plane ∞

Aspherical data 13th surface
K = 0.00000e + 000 A 4 = -4.63158e-005 A 6 = 4.90655e-007 A 8 = -2.56615e-009 A10 = -7.48627e-011

14th page
K = 0.00000e + 000 A 4 = -2.80673e-005 A 6 = 1.33478e-006 A 8 = -1.48174e-008 A10 = -2.75633e-011

18th page
K = 0.00000e + 000 A 4 = -2.52457e-004 A 6 = 4.57873e-006 A 8 = -3.79259e-008 A10 = 5.90443e-010

19th page
K = 0.00000e + 000 A 4 = 2.74061e-004 A 6 = 4.18580e-006 A 8 = 1.07312e-008 A10 = 1.05423e-009

Various data Zoom ratio 3.90

Focal length 5.31 10.25 20.71
F number 1.84 2.62 3.80
Half angle of view (degrees) 46.03 28.21 14.88
Image height 5.50 5.50 5.50
Total lens length 74.94 74.94 74.94
BF 5.25 14.64 24.69

d 8 13.31 12.04 2.10
d11 9.37 2.77 0.91
d19 2.59 1.07 2.82
d23 1.85 11.24 21.28

Zoom lens group data group Start surface Focal length
1 1 -18.79
2 9 -24.86
3 12 12.93
4 20 -63.12

[Numeric data 3]
Unit mm

Surface data surface number rd nd νd
1 30.155 1.30 1.69680 55.5
2 12.293 7.52
3 69.198 1.10 1.69680 55.5
4 26.528 4.22
5 -26.742 0.80 1.59522 67.7
6 33.613 1.12
7 29.942 3.90 1.95906 17.5
8 170.469 (variable)
9 -10.677 0.50 1.49700 81.5
10 -53.436 (variable)
11 (Aperture) ∞ 0.40
12 * 10.759 3.80 1.55332 71.7
13 * -47.271 0.17
14 17.209 5.00 1.43700 95.1
15 -12.942 0.45 1.91650 31.6
16 31.092 0.72
17 * 9.725 4.80 1.55332 71.7
18 * -21.375 (variable)
19 -339.049 1.26 1.94595 18.0
20 -25.356 2.05
21 -16.022 0.60 1.76182 26.5
22 126.374 (variable)
23 ∞ 2.00 1.54400 60.0
Image plane ∞

Aspheric data 12th surface
K = 0.00000e + 000 A 4 = -8.19120e-005 A 6 = 5.73929e-007 A 8 = -1.56980e-009 A10 = -2.53005e-010

Side 13
K = 0.00000e + 000 A 4 = -6.12498e-005 A 6 = 2.10300e-006 A 8 = -2.09520e-008 A10 = -1.87732e-010

17th page
K = 0.00000e + 000 A 4 = -3.11039e-004 A 6 = 4.63120e-006 A 8 = -4.78806e-008 A10 = 2.26405e-010

18th page
K = 0.00000e + 000 A 4 = 2.43140e-004 A 6 = 3.08615e-006 A 8 = 1.32269e-010 A10 = 3.15201e-010

Various data Zoom ratio 2.89

Focal length 4.91 8.08 14.19
F number 1.67 2.22 3.00
Half angle of view (degrees) 48.24 34.25 21.18
Image height 5.50 5.50 5.50
Total lens length 65.22 65.22 65.22
BF 5.94 13.08 20.74

d 8 8.47 8.32 2.22
d10 8.05 2.86 0.96
d18 3.03 1.23 1.59
d22 1.20 8.33 15.99

Zoom lens group data group Start surface Focal length
1 1 -14.36
2 9 -26.95
3 11 12.00
4 19 -65.30

[Numeric data 4]
Unit mm

Surface data surface number rd nd νd
1 38.472 1.70 1.69680 55.5
2 18.387 6.93
3 45.363 1.30 1.69680 55.5
4 17.536 5.48
5 165.663 0.90 1.59522 67.7
6 20.071 4.90
7 21.605 1.24 1.95906 17.5
8 31.757 (variable)
9 -12.502 1.00 1.89286 20.4
10 -10.739 0.45 1.69680 55.5
11 -41.108 (variable)
12 (Aperture) ∞ 0.40
13 * 9.378 3.51 1.58313 59.4
14 * -53.700 0.71
15 9.486 3.75 1.49700 81.5
16 -12.581 0.45 1.90366 31.3
17 14.105 1.35
18 * 12.741 3.62 1.49710 81.6
19 * 64.411 4.69
20 12.093 3.26 1.85478 24.8
21 11.946 (variable)
22 ∞ 2.00 1.54400 60.0
Image plane ∞

Aspherical data 13th surface
K = 0.00000e + 000 A 4 = 1.28333e-005 A 6 = 3.96145e-007 A 8 = -8.52497e-009 A10 = -4.16640e-011

14th page
K = 0.00000e + 000 A 4 = 9.89357e-005 A 6 = -5.06533e-008 A 8 = -2.57349e-008 A10 = 1.87913e-010

18th page
K = 0.00000e + 000 A 4 = -1.95853e-004 A 6 = -6.38323e-006 A 8 = -3.89524e-007 A10 = -7.96355e-009

19th page
K = 0.00000e + 000 A 4 = 4.11532e-004 A 6 = 5.70748e-006 A 8 = -7.64341e-007 A10 = 7.54527e-009

Various data Zoom ratio 3.90

Focal length 4.80 9.35 18.72
F number 1.86 2.95 4.63
Half angle of view (degrees) 48.89 30.47 16.37
Image height 5.50 5.50 5.50
Total lens length 71.30 71.30 71.30
BF 4.41 11.81 22.90

d 8 9.97 11.29 2.13
d11 11.27 2.56 0.62
d21 2.41 9.80 20.90

Zoom lens group data group Start surface Focal length
1 1 -17.47
2 9 -28.87
3 12 11.34

[Numeric data 5]
Unit mm

Surface data surface number rd nd νd
1 36.756 1.70 1.69680 55.5
2 15.125 6.94
3 40.147 1.30 1.69680 55.5
4 14.976 5.15
5 -505.394 0.90 1.59522 67.7
6 25.274 0.99
7 20.849 1.44 1.95906 17.5
8 36.871 (variable)
9 -13.931 1.00 1.89286 20.4
10 -12.807 0.45 1.69680 55.5
11 -150.001 (variable)
12 (Aperture) ∞ 0.10
13 * 9.866 2.73 1.58313 59.4
14 * 70.012 0.52
15 10.411 2.87 1.49700 81.5
16 -118.079 0.45 1.90366 31.3
17 13.626 2.03
18 * 8.670 3.36 1.49710 81.6
19 * -62.272 (variable)
20 -8.755 0.60 1.85478 24.8
21 -10.750 (variable)
22 ∞ 2.00 1.54400 60.0
Image plane ∞

Aspherical data 13th surface
K = 0.00000e + 000 A 4 = -4.71946e-005 A 6 = -5.94910e-007 A 8 = 3.15429e-009 A10 = -2.94864e-010

14th page
K = 0.00000e + 000 A 4 = -1.40642e-005 A 6 = 6.52379e-007 A 8 = -4.60192e-008 A10 = 3.18797e-010

18th page
K = 0.00000e + 000 A 4 = -3.07501e-004 A 6 = 5.74877e-007 A 8 = -3.64648e-008 A10 = -6.56242e-009

19th page
K = 0.00000e + 000 A 4 = 3.37333e-004 A 6 = 3.52790e-006 A 8 = -1.00775e-007 A10 = -5.00773e-009

Various data Zoom ratio 3.94

Focal length 4.77 9.09 18.81
F number 1.86 2.89 4.28
Half angle of view (degrees) 49.04 31.19 16.30
Image height 5.50 5.50 5.50
Total lens length 69.30 69.30 69.30
BF 2.69 2.69 2.69

d 8 13.40 12.35 1.59
d11 9.22 2.11 0.63
d19 11.48 19.64 31.89
d21 0.68 0.68 0.68

Zoom lens group data group Start surface Focal length
1 1 -15.15
2 9 -23.04
3 12 12.11
4 20 -64.06
5 22 ∞

[Numeric data 6]
Unit mm

Surface data surface number rd nd νd
1 81.184 1.70 1.69680 55.5
2 24.232 3.30
3 27.212 1.30 1.69680 55.5
4 15.792 9.55
5 -509.580 0.90 1.59522 67.7
6 25.972 3.97
7 19.772 1.53 1.95906 17.5
8 26.298 (variable)
9 -14.945 1.00 1.89286 20.4
10 -13.068 0.45 1.69680 55.5
11 -35.965 (variable)
12 (Aperture) ∞ 0.31
13 * 10.590 4.40 1.58313 59.4
14 * -63.791 0.64
15 13.792 4.02 1.49700 81.5
16 -15.737 0.45 1.90366 31.3
17 15.450 1.30
18 * 9.506 5.36 1.49710 81.6
19 * 60.521 (variable)
20 36.387 1.00 1.95906 17.5
21 497.918 (variable)
22 -14.552 0.60 1.74950 35.3
23 -58.270 (variable)
24 ∞ 2.00 1.54400 60.0
Image plane ∞

Aspherical data 13th surface
K = 0.00000e + 000 A 4 = -3.56184e-005 A 6 = 3.77001e-007 A 8 = -4.93177e-009 A10 = -6.61398e-011

14th page
K = 0.00000e + 000 A 4 = 7.28817e-006 A 6 = 1.02043e-006 A 8 = -2.06961e-008 A10 = 7.28757e-011

18th page
K = 0.00000e + 000 A 4 = -1.78046e-004 A 6 = 2.77005e-007 A 8 = -9.53773e-008 A10 = -1.70793e-009

19th page
K = 0.00000e + 000 A 4 = 2.67227e-004 A 6 = 5.88560e-006 A 8 = -3.01472e-007 A10 = 1.98075e-009

Various data Zoom ratio 5.90

Focal length 4.55 11.60 26.82
F number 1.82 3.14 5.05
Angle of view 50.40 25.37 11.59
Image height 5.50 5.50 5.50
Total lens length 84.30 84.30 84.30
BF 2.62 14.56 32.48

d 8 15.34 20.43 3.53
d11 17.64 1.25 1.20
d19 4.08 3.95 3.77
d21 2.84 2.32 1.55
d23 0.61 12.56 30.48

Zoom lens group data group Start surface Focal length
1 1 -18.92
2 9 -41.58
3 12 14.48
4 20 40.89
5 22 -26.03

L1 First lens group L2 Second lens group L3 Third lens group L4 Fourth lens group L5 Fifth lens group

Claims (14)

A first lens group having a negative refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side to the image side;
During zooming, the first lens group is stationary, the second lens group and the third lens group move, and the distance between adjacent lens groups changes, and the first lens group is 2 Have more than one negative lens,
The focal length of the first lens group is f1, the focal length of the entire system at the wide angle end is fw, the focal length of the entire system at the telephoto end is ft, and the optical axis of the first lens group and the second lens group at the wide angle end Is set to D12w and the back focus at the wide angle end is set to BFw.
0.70 <| f1 / √ (fw × ft) | <2.70
0.60 <D12w / BFw <5.30
A zoom lens satisfying the following conditional expression: When the focal length of the first lens group is f1, and the focal length of the second lens group is f2,
0.10 <f1 / f2 <1.00
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the amount of movement of the third lens unit in zooming from the wide-angle end to the telephoto end is M3wt, and the focal length of the third lens unit is f3,
0.50 <| M3wt | / f3 <3.00
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the distance from the most object side lens surface of the first lens group to the most image side lens surface of the first lens group is TL1G, and the focal length of the entire system at the wide angle end is fw,
3.00 <TL1G / fw <6.00
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the second lens group is f2, and the focal length of the third lens group is f3,
−3.20 <f2 / f3 <−1.20
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the third lens group is f3 and the focal length of the entire system at the telephoto end is ft,
0.30 <f3 / ft <1.00
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the distance from the lens surface closest to the object side to the image plane is TL and the back focus at the wide angle end is BFw,
5.0 <TL / BFw <35.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.   The second lens group includes one lens or one cemented lens obtained by cementing a plurality of lenses, and the lens surface closest to the object side of the second lens group is concave. Item 8. The zoom lens according to any one of Items 1 to 7.   The zoom lens according to claim 1, wherein the second lens group moves during focusing.   The zoom lens from the wide angle end to the telephoto end, the second lens group moves to the object side after moving to the image side, and the third lens group moves to the object side. The zoom lens according to claim 1.   11. The fourth lens group according to claim 1, further comprising a fourth lens group having a negative refractive power on the image side of the third lens group, and the fourth lens group moves during zooming. Zoom lens.   A fourth lens group having a positive refractive power disposed on the image side of the third lens group, and a fifth lens group having a negative refractive power disposed adjacent to the image side of the fourth lens group; The zoom lens according to any one of claims 1 to 10, wherein the fourth lens group and the fifth lens group move during zooming.   An image pickup apparatus comprising: the zoom lens according to claim 1; and an image pickup element that receives an image formed by the zoom lens. When the imaging half field angle at the wide angle end is ωw, the imaging half field angle at the telephoto end is ωt, the lateral magnification of the third lens group at the wide angle end is β3w, and the lateral magnification of the third lens group at the telephoto end is β3t. ,
1.50 <(tan ωw / tan ωt) / (β3t / β3w) <7.00
The image pickup apparatus according to claim 13, wherein the following conditional expression is satisfied.