JP2019028258A - Zoom lens and imaging apparatus having the same - Google Patents

Abstract

To obtain a zoom lens that has a short lens total length, a small lens effective diameter, a light lens weight as a whole, facilitates quick focusing, and gives high optical performance over the entire zoom range and the entire object distance.SOLUTION: The zoom lens comprises a first lens group having a positive refractive power, a second lens group having a negative refractive power, an intermediate group including at least one lens group, an (N-1)-th lens group having a negative refractive power, and an N-th lens group having a positive refractive power, in which upon zooming from a wide angle end to a telephoto end, the first lens group moves toward an object side, and the (N-1)-th lens group has a lens made of a resin and moves in an optical axis direction upon focusing. A lateral magnification βnw of the N-th lens group at the wide angle end, a back focus skw at the wide angle end, a focal distance fw of the whole system at the wide angle end and a lens total length Dw at the wide angle end are each appropriately set.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a zoom lens and an image pickup apparatus having the same, and is suitable as an image pickup optical system of an image pickup apparatus such as a digital camera, a video camera, a broadcast camera, and a surveillance camera.

  In recent years, imaging devices have become highly functional. Accordingly, an imaging optical system used in the imaging apparatus is required to be a zoom lens having a high zoom ratio (magnification ratio), high optical performance over the entire zoom range, and a short total lens length. In addition, in order to perform quick focusing (focusing), the focus lens group is small and lightweight, and it is required that there is no image deterioration or image shake during focusing.

  As a zoom lens that satisfies these requirements, there is a rear focus type zoom lens that performs focusing with a lens group other than the first lens group on the object side, which is a positive lead type lens group having a positive refractive power closest to the object side. Known (Patent Documents 1 to 3).

  In Patent Document 1, in order from the object side to the image side, the first lens group to the sixth lens group having positive, negative, positive, negative, negative, and positive refractive powers are arranged, and the distance between adjacent lens groups changes during zooming. A zoom lens is disclosed. Patent Document 1 discloses a zoom lens having a zoom ratio of about 4 for performing focusing by moving the fourth lens group.

  In Patent Document 2, the first lens group to the sixth lens group having positive, negative, positive, negative, positive, and negative refractive powers are sequentially arranged from the object side to the image side, and the distance between adjacent lens groups changes during zooming. A zoom lens is disclosed. In Patent Document 2, the fourth lens group is moved during focusing. In Patent Document 3, zoom is made up of first to fifth lens groups having positive, negative, positive, negative, and positive refractive power in order from the object side to the image side, and the distance between adjacent lens groups changes during zooming. A lens is disclosed. In Patent Document 3, a part of the second lens group is moved during focusing.

JP 2012-47814 A JP 2006-251462 A JP 2010-32702 A

  Zoom lenses used in imaging devices are strongly requested to have a short overall lens length, a compact lens system, high optical performance over the entire zoom range with a high zoom ratio, and low aberration fluctuation during focusing. ing. In addition, there is a demand for an appropriate length of the back focus, a lens configuration in which the diameter of the lens barrel becomes small when incorporated in the lens barrel, and the like.

  In order to satisfy these requirements in a positive lead type zoom lens, it is important to appropriately set each element constituting the zoom lens. For example, it is important to appropriately set the zoom type (the number of lens groups and the sign of the refractive power of each lens group) and the selection of a focusing lens group that strongly affects the size of the lens barrel diameter. come.

  The zoom lens of Patent Document 1 reduces the variation in aberrations associated with zooming while increasing the zoom ratio by reducing the distance between the fourth lens group and the fifth lens group during zooming from the wide-angle end to the telephoto end. When the zoom ratio is increased in this zoom lens, the distance between the fourth lens group and the fifth lens group tends to be reduced at the telephoto end. When the distance between the fourth lens unit and the fifth lens unit becomes small at the telephoto end, the space for moving the fourth lens unit to the image side during focusing from infinity to a short distance is reduced, and focusing can be performed at a wide object distance. It becomes difficult.

  The zoom lens of Patent Document 2 is a mirrorless type zoom lens, and the total lens length is relatively short. However, since the refractive power of the last lens unit having a negative refractive power and the lens unit having a positive refractive power that is one object side from the final lens group are too strong, it is difficult to obtain high optical performance over the entire zoom range. The zoom lens of Patent Document 3 has a long back focus and tends to make it difficult to shorten the entire length of the lens.

  The present invention provides a zoom lens having a short overall lens length, a small effective lens diameter, a light weight as a whole, easy focusing, and high optical performance over the entire zoom range and the entire object distance, and an imaging having the same An object is to provide an apparatus.

The zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, an intermediate group including one or more lens groups, a negative group A zoom lens in which the distance between adjacent lens groups changes during zooming, the (N-1) th lens group having a refractive power of N and the Nth lens group having a positive refractive power,
The first lens group moves to the object side during zooming from the wide-angle end to the telephoto end,
The (N-1) th lens group has a lens made of resin, moves in the optical axis direction during focusing,
When the lateral magnification of the Nth lens group at the wide angle end is βnw, the back focus at the wide angle end is skw, the focal length of the entire system at the wide angle end is fw, and the total lens length at the wide angle end is Dw,
0.8 <βnw <2.0
0.5 <skw / fw <4.0
2.0 <Dw / fw <11.0
It satisfies the following conditional expression.

  According to the present invention, it is possible to obtain a zoom lens having a short overall lens length, a small effective lens diameter, a light weight as a whole, easy focusing quickly, and high optical performance over the entire zoom range and the entire object distance. .

Sectional view of the lens at the wide-angle end of Embodiment 1 of the present invention (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of Embodiment 1 of the present invention. Sectional view of the lens at the wide-angle end of Example 2 (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of Embodiment 2 of the present invention. Sectional view of the lens at the wide-angle end of Embodiment 3 (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of Embodiment 3 of the present invention. Cross-sectional view of a lens at a wide angle end according to Embodiment 4 of the present invention (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of Embodiment 4 of the present invention. Lens cross-sectional view at the wide angle end according to Embodiment 5 of the present invention (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of Embodiment 5 of the present invention. Schematic diagram of essential parts of the optical apparatus of the present invention

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. The zoom lens according to each embodiment of the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and one or more lens groups arranged in order from the object side to the image side. The lens unit includes an intermediate group, a (N−1) th lens group having a negative refractive power, and an Nth lens group having a positive refractive power. The distance between adjacent lens groups changes during zooming, and the first lens group moves to the object side during zooming from the wide-angle end to the telephoto end. The (N-1) th lens group has a lens (resin lens) made of resin, and moves in the optical axis direction during focusing.

  FIG. 1 is a lens cross-sectional view at the wide angle end according to Embodiment 1 of the present invention. 2A, 2B, and 2C are longitudinal aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens of Example 1. FIGS. FIG. 3 is a lens cross-sectional view at the wide angle end according to the second embodiment of the present invention. 4A, 4B, and 4C are longitudinal aberration diagrams of the zoom lens of Embodiment 2 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively.

  FIG. 5 is a lens cross-sectional view at the wide angle end according to Embodiment 3 of the present invention. 6A, 6B, and 6C are longitudinal aberration diagrams of the zoom lens of Example 3 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively. FIG. 7 is a lens cross-sectional view at the wide angle end according to Embodiment 4 of the present invention. 8A, 8B, and 8C are longitudinal aberration diagrams of the zoom lens of Example 4 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively.

  FIG. 9 is a lens cross-sectional view at the wide-angle end according to Embodiment 5 of the present invention. FIGS. 10A, 10B, and 10C are longitudinal aberration diagrams of the zoom lens at the wide-angle end of Embodiment 5 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively. FIG. 11 is a schematic diagram of a main part of the imaging apparatus of the present invention.

  The zoom lens of each embodiment is a zoom lens used in an imaging apparatus such as a digital camera, a video camera, a broadcast camera, or a surveillance camera. The zoom lens of the embodiment can also be used as a projection optical system for a projection apparatus (projector). In the lens cross-sectional view, the left side is the object side (front), and the right side is the image side (rear). In the lens cross-sectional view, when i is the order of the lens group from the object side, Li indicates the i-th lens group.

  LM is an intermediate group including one or more lens groups. L (N-1) is the (N-1) th lens unit having a negative refractive power. LN is an Nth lens unit having a positive refractive power. SP is an aperture stop. G is a glass block such as a face plate or a filter. IP is the image plane. The image plane IP corresponds to an imaging plane of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor when a zoom lens is used as an imaging device such as a digital camera or a video camera. The arrow indicates the movement locus during zooming from the wide-angle end to the telephoto end.

  The arrow related to the focus (FOCUS) indicates that the (N-1) th lens unit L (N-1) moves to the image side during focusing from infinity to a short distance. In the spherical aberration diagram, Fno is an F number. The solid line d is the d line (wavelength 587.6 nm), and the two-dot chain line g is the g line (wavelength 435.8 nm). The dotted line is a sine condition. In the astigmatism diagram, the dotted line ΔM is the meridional image plane at the d line, and the solid line ΔS is the sagittal image plane at the d line. The distortion diagram shows the d-line. The lateral chromatic aberration diagram shows the g-line. ω is a half angle of view (degree).

  The zoom lens of each embodiment mainly performs zooming by moving the first lens unit L1 and the second lens unit L2. During zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves toward the object side, thereby reducing the effective diameter of the front lens at the wide-angle end and increasing the zoom ratio.

  In Examples 1, 2, and 4, the intermediate group LM is arranged in order from the object side to the image side, the third lens group having a positive refractive power, the fourth lens group having a negative refractive power, and the first lens having a positive refractive power. It consists of five lens groups. In Examples 3 and 5, the intermediate group LM includes a third lens group having a positive refractive power and a fourth lens group having a positive refractive power, which are arranged in order from the object side to the image side.

  In a positive lead type zoom lens, in order to shorten the total lens length, it is effective to dispose a lens group having a strong positive refractive power in the vicinity of the last lens group, followed by a lens group having a strong negative refractive power. In order to effectively use the back focus and shorten the total lens length, it is effective to sequentially dispose a lens group having a negative refractive power and a lens group having a positive refractive power on the image side in order. Further, when the final lens group has a positive refractive power, the incident angle of the light beam on the image plane can be reduced, and so-called shading such as a decrease in the amount of light in the peripheral image height and coloring due to the image sensor can be easily suppressed. Become.

  In the present invention, by appropriately setting the negative refracting power of the (N-1) th lens unit L (N-1) and the positive refracting power of the Nth lens unit LN, the focus surface with respect to the movement of the focus lens unit is set. The focus sensitivity, which is the ratio of movement, is set appropriately. As a result, the amount of movement at the time of focusing is reduced, the degree of freedom of arrangement of mechanical members is increased, and the lens barrel diameter is reduced.

In each embodiment, the lateral magnification of the Nth lens group at the wide angle end is βnw, the back focus at the wide angle end is skw, the focal length of the entire system at the wide angle end is fw, and the total lens length at the wide angle end is Dw. At this time,
0.8 <βnw <2.0 (1)
0.5 <skw / fw <4.0 (2)
2.0 <Dw / fw <11.0 (3)
The following conditional expression is satisfied.

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (1) sets the lateral magnification βnw of the final Nth lens unit LN at the wide angle end in order to set an appropriate focus sensitivity for the (N-1) th lens unit L (N-1) for focusing. It prescribes. If the lateral magnification βnw exceeds the upper limit of conditional expression (1), the focus sensitivity of the (N-1) th lens unit L (N-1) becomes too high, and mechanical control becomes difficult during focusing.

  When the lateral magnification βnw is reduced beyond the lower limit of conditional expression (1), the focus sensitivity of the (N-1) th lens unit L (N-1) is lowered, the optical performance at the closest point is lowered, and the first (N-1) The length of the lens group L (N-1) in the optical axis direction increases.

  Conditional expression (2) defines the back focus skw, which is the length from the final lens surface to the image plane at the wide-angle end, and the focal length fw of the entire system at the wide-angle end in order to reduce the total lens length at the wide-angle end. doing. Here, the back focus skw is an air-converted distance from the final lens surface to the image plane. The total lens length is a value obtained by adding back focus to the distance from the first lens surface to the final lens surface.

  If the upper limit of the conditional expression (2) is exceeded and the back focus skw becomes longer, the back focus becomes unnecessarily longer and the total lens length at the wide angle end becomes longer. Alternatively, when the focal length fw is shortened, the effective diameter of the front lens is increased.

  If the lower limit of the conditional expression (2) is exceeded and the back focus skw is shortened, the positive refractive power of the Nth lens unit LN needs to be increased in order to suppress the increase in the incident angle of the light beam on the image plane, and so Performance will decrease. Further, it is not good because the space for inserting the protective glass of the image sensor and various filters is reduced. Alternatively, if the focal length fw becomes too long, it becomes difficult to achieve a high zoom ratio with a wide angle of view.

  Conditional expression (3) defines the total lens length Dw at the wide angle end and the focal length fw of the entire system at the wide angle end in order to shorten the total lens length at the wide angle end. When the total lens length Dw is increased beyond the upper limit of conditional expression (3), it is difficult to shorten the total lens length with respect to the focal length of the entire system at the wide angle end. Alternatively, when the focal length fw is shortened, the effective diameter of the front lens becomes too large, and it becomes difficult to reduce the size of the entire system.

  If the lower limit of the conditional expression (3) is exceeded and the lens total length Dw is shortened, it is necessary to increase the refractive power of each lens group, and it becomes difficult to correct various aberrations. Alternatively, if the focal length fw becomes too long, it becomes difficult to achieve a high zoom ratio with a wide angle of view.

Preferably, the numerical ranges of conditional expressions (1) to (3) are set as follows.
0.8 <βnw <1.5 (1a)
0.5 <skw / fw <3.0 (2a)
3.0 <Dw / fw <10.0 (3a)
More preferably, the numerical ranges of the conditional expressions (1a) to (3a) are set as follows.
0.8 <βnw <1.0 (1b)
0.5 <skw / fw <1.0 (2b)
4.0 <Dw / fw <6.0 (3b)

  As described above, according to the present invention, in a positive lead type zoom lens, a zoom lens having a small overall lens length and a small lens diameter, a small lens mass, and high focusing performance can be easily obtained.

  In this embodiment, it is more preferable to satisfy one or more of the following conditional expressions. The focal length of the (N-1) th lens unit L (N-1) is f (n-1). Let the focal length of the Nth lens unit LN be fn. The lateral magnification of the (N−1) th lens group L (N−1) at the telephoto end is β (n−1) t, and the lateral magnification of the Nth lens group LN at the telephoto end is βnt.

  The average value of the specific gravity of the lens materials included in the (N-1) th lens unit L (N-1) is defined as Davg. Here, the specific gravity of the material is the mass of the material used for the lens at room temperature (15 ° C. to 25 ° C.) and the mass of pure water at 4 ° C. under the same volume pressure of 101.325 kPa (standard atmospheric pressure). The ratio of Let the focal length of the first lens unit L1 be f1. The distance from the image plane at the wide angle end to the exit pupil position is defined as POw.

When the (N-1) th lens group L (N-1) includes a positive lens made of resin and a negative lens made of resin, the resin contained in the (N-1) th lens group L (N-1). The focal length of the negative lens is f (n-1) n. The refractive index temperature coefficient (10 ⁻⁶ / ° C.) of the material of the negative lens is dn (n−1) n / dT. The focal length of the positive lens made of resin contained in the (n−1) th lens group L (N−1) is f (n−1) p, and the refractive index temperature coefficient of the positive lens material (10 ⁻⁶ / ° C.). Is dn (n-1) p / dT.

At this time, one or more of the following conditional expressions should be satisfied.
−5.0 <f (n−1) / fw <−1.0 (4)
-1.0 <f (n-1) / fn <-0.1 (5)
−10.0 <(1-β (n−1) t ² ) βnt ² <−1.5 (6)
1.0 <Davg <2.5 (7)
3.0 <fn / skw <30.0 (8)
2.0 <f1 / fw <8.0 (9)
-4.0 <POw / fw <-1.0 (10)
−50.0 <(1 / f (n−1) n × dn (n−1) n / dT) / (1 / f (n−1) p × dn (n−1) p / dT) <− 1.0 (11)

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (4) is for ensuring high focusing performance and reducing the size of the focus lens group. Conditional expression (4) defines the focal length f (n-1) of the (N-1) th lens unit L (N-1), which is the focus lens unit, and the focal length fw of the entire system at the wide angle end. .

  If the upper limit of conditional expression (4) is exceeded and the focal length f (n−1) is increased, it becomes difficult to sufficiently increase the focus sensitivity, the amount of movement during focusing increases, and the mechanical configuration increases. . Alternatively, when the focal length fw is shortened, the effective diameter of the front lens is increased. If the lower limit of conditional expression (4) is exceeded and the focal length f (n−1) is shortened, the refractive power of the focus lens group becomes too strong, and it becomes difficult to ensure good optical performance at short distances. Alternatively, when the focal length fw is increased, it is difficult to obtain a zoom lens having a wide angle of view and a high zoom ratio.

  Conditional expression (5) indicates that the focal length f (n−1) of the (N−1) th lens group L (N−1), which is the focus lens group, and the Nth lens group LN in order to realize high focusing performance. The focal length ratio of the focal length fn is defined. If the upper limit of conditional expression (5) is exceeded and the focal length f (n−1) is increased, the focus sensitivity is lowered, the amount of movement of the focus lens group for short-distance shooting increases, and the optical performance during short-distance shooting. Will fall.

  In addition, since the moving amount of the (N-1) th lens unit L (N-1) becomes long, the mechanical configuration becomes large, and it becomes difficult to reduce the size of the lens barrel. Alternatively, when the focal length fn is shortened, the focus sensitivity of the (N-1) th lens unit L (N-1) becomes too high, and the control of the (N-1) th lens unit L (N-1) is difficult. It becomes.

  If the lower limit of conditional expression (5) is exceeded and the focal length f (n−1) is shortened, the negative refractive power of the (N−1) th lens unit L (N−1) becomes too strong (negative). It becomes difficult to maintain good optical performance at short distances because the absolute value of the refractive power becomes too large. In addition, the light beam is greatly kicked up near the image plane, and it becomes difficult to correct curvature of field and lateral chromatic aberration. Alternatively, when the focal length fn is increased, it becomes difficult to sufficiently refract the light beam kicked up by the (N−1) th lens unit L (N−1), and a lot of shading occurs.

  In order to obtain high focusing performance at the telephoto end, the conditional expression (6) satisfies the lateral magnification β (n−1) t at the telephoto end of the (N−1) th lens unit L (N−1) as the focus lens unit, and The lateral magnification βnt of the final Nth lens unit LN at the telephoto end is defined. Conditional expression (6) relates to the focus sensitivity at the telephoto end.

  If the focus sensitivity is increased beyond the upper limit of conditional expression (6), it becomes difficult to control the (N-1) th lens unit L (N-1) with high accuracy. Further, the refractive power of the (N-1) th lens unit L (N-1) is increased, and it becomes difficult to obtain good optical performance at the time of shooting at a short distance. If the lower limit of conditional expression (6) is exceeded and the focus sensitivity decreases, the amount of movement of the lens unit during focusing increases, making it difficult to downsize the entire system.

  Conditional expression (7) indicates that all of the components of the (N−1) th lens unit L (N−1) are implemented in order to reduce the weight of the focusing (N−1) th lens unit L (N−1). The average value Davg of the specific gravity of each lens is defined. When the average specific gravity Davg increases beyond the upper limit of conditional expression (7), the lens mass of the (N-1) th lens group L (N-1) increases, and the (N-1) th lens group L (N The unit for driving and controlling -1) is increased in size, making it difficult to reduce the weight. There is currently no resin / glass material that has an average specific gravity Davg that is lower than the lower limit of conditional expression (7).

  Conditional expression (8) is for suppressing the shading of the peripheral rays at the wide-angle end and shortening the total lens length. Conditional expression (8) defines the focal length fn of the Nth lens unit LN, which is the final lens unit, and the back focus skw at the wide-angle end. When the upper limit of conditional expression (8) is exceeded and the focal length fn is increased, the refractive power of the Nth lens unit LN is weakened, the incident angle of peripheral rays on the imaging surface is increased, and a large amount of shading occurs. In addition, since the focal length of the Nth lens unit LN is increased, it is difficult to increase the focus sensitivity of the (N-1) th lens unit L (N-1), so it is difficult to shorten the total lens length. become.

  Alternatively, if the back focus skw is shortened, the space for inserting the protective glass of the image sensor and various filters is reduced, which is not good.

  If the lower limit of conditional expression (8) is exceeded and the focal length fn is shortened, the refractive power of the Nth lens unit LN becomes too strong, and aberrations to the peripheral image height such as field curvature increase. In addition, the focus sensitivity of the adjacent (N-1) th lens unit L (N-1) becomes high, and it becomes difficult to perform focus control with high accuracy. Alternatively, when the back focus skw becomes long, the back focus becomes unnecessarily long, and the total lens length at the wide angle end becomes long.

  Conditional expression (9) defines the focal length fw of the entire system at the wide-angle end and the focal length f1 of the first lens unit L1 in order to obtain a high zoom ratio. When the focal length of the first lens unit L1 exceeds the upper limit of conditional expression (9), it becomes easy to correct lateral chromatic aberration at the wide-angle end and axial chromatic aberration at the telephoto end. The amount of movement of the first lens unit L1 increases, and the total lens length increases.

  When the lower limit of conditional expression (9) is exceeded and the focal length of the first lens unit L1 is shortened, the entire system can be easily reduced in size, but spherical aberration, coma aberration, etc. can be corrected with a small number of lenses. It becomes difficult. Furthermore, the focal length of the entire system at the wide-angle end becomes long, and it becomes difficult to secure a desired zoom ratio.

  Conditional expression (10) defines the relationship between the distance POw to the exit pupil position at the wide angle end and the focal length fw of the entire system at the wide angle end in order to ensure high telecentricity. Here, the distance POw related to the exit pupil position is defined as negative when it is on the object side from the image plane. If the distance POw is longer than the upper limit of the conditional expression (10), the refractive power of the Nth lens unit LN becomes strong, and it becomes difficult to satisfactorily suppress field curvature.

  When the distance POw becomes shorter than the lower limit of conditional expression (10), the incident angle of the image plane of the light beam having the peripheral image height becomes too large, and a lot of shading occurs. Alternatively, the focal length fw of the entire system at the wide angle end becomes long, and it becomes difficult to secure a desired zoom ratio.

  Conditional expression (11) corrects out-of-focus and aberration fluctuations caused by temperature fluctuations with a resin lens having positive refractive power and negative refractive power in the (N-1) th lens group L (N-1). It defines the refractive power distribution and refractive index temperature coefficient of both lenses.

Here, dn (n-1) n / dT and dn (n-1) p / dT have the negative refractive power and the positive refractive power of the (N-1) th lens unit L (N-1), respectively. The refractive index temperature coefficient (10 ⁻⁶ / ° C.), which is a physical property value of the resin lens. When the upper limit value of conditional expression (11) is exceeded, the focus shift due to temperature fluctuation increases toward the image side. When the lower limit value of conditional expression (11) is exceeded, the focus shift due to temperature fluctuation increases toward the object side.

In each embodiment, it is preferable to set the numerical ranges of conditional expressions (4) to (11) as follows.
−3.0 <f (n−1) / fw <−1.0 (4a)
−0.8 <f (n−1) / fn <−0.1 (5a)
−9.0 <(1-β (n−1) t ² ) βnt ² <−1.6 (6a)
1.0 <Davg <1.6 (7a)
3.5 <fn / skw <25.0 (8a)
2.5 <f1 / fw <7.0 (9a)
−3.5 <POw / fw <−1.2 (10a)
−10.0 <(1 / f (n−1) n × dn (n−1) n / dT) / (1 / f (n−1) p × dn (n−1) p / dT) <−. 1.5 (11a)

More preferably, in each embodiment, the numerical ranges of the conditional expressions (4a) to (11a) are set as follows.
−2.0 <f (n−1) / fw <−1.3 (4b)
−0.60 <f (n−1) / fn <−0.11 (5b)
−8.0 <(1-β (n−1) t ² ) βnt ² <−1.7 (6b)
1.0 <Davg <1.3 (7b)
4.5 <fn / skw <22.0 (8b)
3.0 <f1 / fw <6.0 (9b)
−3.0 <POw / fw <−1.5 (10b)
−5.0 <(1 / f (n−1) n × dn (n−1) n / dT) / (1 / f (n−1) p × dn (n−1) p / dT) <− 2.0 (11b)

  Next, a preferable configuration in each embodiment will be described. The (N-1) th lens unit L (N-1) which is the focus lens unit is required to be as light as possible in order to increase the focusing speed. Therefore, it is preferable that the (N-1) th lens group L (N-1) is composed of two or less lenses or one single lens. The resin lens included in the (N-1) th lens group L (N-1) uses one positive resin lens and one negative resin lens in order to reduce the focus and aberration fluctuations due to temperature fluctuations. It is desirable to reduce aberration fluctuations due to temperature changes in the (N-1) th lens group L (N-1).

  The Nth lens unit LN is positively refracted in order to mitigate a change in aberration caused by a temperature change generated by the resin lens having the negative refractive power of the (N-1) th lens unit L (N-1). It is desirable to use a force resin lens. In order to achieve a high zoom ratio with a wide angle of view while reducing the size of the entire system, the smaller the number of lenses in the first lens unit L1, the lower the incident height of the off-axis light beam passing through the first lens unit L1. In addition, the effective diameter of the first lens unit L1 can be reduced. Therefore, the number of lenses in the first lens unit L1 is preferably 4 or less.

  The second lens group preferably includes two negative lenses and one or more positive lenses arranged in order from the object side to the image side in order to facilitate a wide angle of view. By disposing a lens having a positive refractive power, it becomes easy to converge the light beam and to reduce the effective diameter of the rear lens group. In addition, it is easy to widen the angle of view by setting the second lens group to have a negative refractive power and a lens configuration preceding the negative lens.

  In addition, it is preferable to introduce an aspherical surface into the third lens unit L3, and to appropriately set the refractive power of the second lens unit L2 and the lenses after the third lens unit L3. In particular, astigmatism and distortion can be easily corrected. Further, it becomes easy to correct spherical aberration and coma aberration when the angle of view is widened and the zoom ratio is increased.

  In each embodiment, by configuring each element as described above, a zoom lens having a short lens total length, a small lens diameter, a light lens mass, and high focusing performance is obtained.

  Next, the lens configuration of each example will be described. The first embodiment is a zoom lens having a zoom ratio of 7.7 and an aperture ratio (F number) of about 3.7 to 6.3. The zoom lens according to the first exemplary embodiment is arranged in order from the object side to the image side, and includes seven groups including the first lens unit L1 to the seventh lens unit L7 having positive, negative, positive, negative, positive, negative, and positive refractive power. It is a zoom lens. The sixth lens group L6 corresponds to the (N-1) th lens group L (N-1), and the seventh lens group L7 corresponds to the Nth lens group LN.

  During zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves linearly toward the object side. The second lens unit L2 moves along a locus convex toward the image side. The aperture stop SP, the third lens unit L3, and the fifth lens unit L5 are moved together toward the object side (same locus). The fourth lens unit L4, the fifth lens unit L5, and the sixth lens unit L6 move toward the object side along different paths. The sixth lens unit L6 moves during focusing. Each of the two lenses constituting the sixth lens unit L6 is a lens (resin lens) made of resin.

  Example 2 is a zoom lens having a zoom ratio of about 7.7 and an aperture ratio of about 3.6 to 6.3. In the second embodiment, the zoom types such as the number of lens groups, the sign of the refractive power of each lens group, and the movement conditions of each lens group during zooming are the same as in the first embodiment. The sixth lens group moves during focusing. Each of the two lenses constituting the sixth lens unit L6 is a resin lens. One positive lens constituting the seventh lens unit L7 is a resin lens.

  Example 3 is a zoom lens having a zoom ratio of 4.3 and an aperture ratio of about 3.3 to 5.6. The zoom lens of Example 3 is a six-unit zoom lens including first, sixth, and sixth lens units L6 having positive, negative, positive, positive, negative, and positive refractive powers arranged in order from the object side to the image side. It is. The fifth lens group L5 corresponds to the (N-1) th lens group L (N-1), and the sixth lens group L6 corresponds to the Nth lens group LN.

  During zooming from the wide-angle end to the telephoto end, the first lens unit moves to the object side. The second lens unit L2 moves along a locus convex toward the image side. The third lens unit L3 to the fifth lens unit L5 move toward the object side along different paths. The aperture stop SP moves integrally with the third lens unit L3. The sixth lens unit L6 does not move during zooming. The two lenses constituting the fifth lens unit L5 to which the fifth lens unit L5 moves during focusing are resin lenses. One positive lens constituting the sixth lens unit L6 is a resin lens.

  The fourth exemplary embodiment is a zoom lens having a zoom ratio of 7.7 and an aperture ratio of about 3.9 to 6.3. In the fourth embodiment, the zoom type is the same as that of the first embodiment. The sixth lens unit L6 moves during focusing. One lens constituting the sixth lens unit L6 is a resin lens.

  Example 5 is a zoom lens having a zoom ratio of 2.5 and an aperture ratio of about 2.0 to 5.0. The zoom lens according to the fifth exemplary embodiment includes a six-unit zoom including first to sixth lens units L1 to L6 having positive, negative, positive, positive, negative, and positive refractive powers arranged in order from the object side to the image side. It is a lens. The fifth lens group L5 corresponds to the (N-1) th lens group L (N-1), and the sixth lens group L6 corresponds to the Nth lens group (LN).

  During zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves linearly toward the object side. The second lens unit L2 moves to the image side. The aperture stop SP disposed between the second lens group L2 and the third lens group L3 moves to the object side along a different locus from the second lens group L2 and the third lens group L3.

  The third lens unit L3 to the fifth lens unit L5 move toward the object side along different paths. The sixth lens unit L6 moves to the image side. Focusing is performed by the fifth lens unit L5. One lens constituting the fifth lens unit L5 is a resin lens. Further, one lens constituting the sixth lens unit L6 is a resin lens.

  Next, an embodiment of a digital still camera (imaging device) using the zoom lens of the present invention as an imaging optical system will be described with reference to FIG. In FIG. 11, 10 is a camera body, and 11 is an image pickup optical system constituted by the zoom lens of the present invention. Reference numeral 12 denotes a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor that receives a subject image formed by the imaging optical system 11 and is built in the camera body.

  The numerical data corresponding to Examples 1 to 5 will be shown below. In each numerical data, i indicates the order counted from the object side, ri is the radius of curvature of the i-th optical surface (i-th surface), and di is on the axis between the i-th surface and the (i + 1) -th surface. Indicates the interval. Ndi and νdi are the refractive index and Abbe number of the material of the i-th optical member with respect to the d-line, respectively. The aspheric shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, A8, and A10 are aspherical surfaces. As a coefficient

It is expressed by the following formula. * Means a surface having an aspherical shape. “E-x” means 10 ^−x . The last two surfaces in the numerical data are surfaces of optical blocks such as filters and face plates.

  In the numerical data 5, the value of the interval d10 is negative because the aperture stop SP and the third lens unit L3 are counted in order from the object side to the image side.

  BF is an air equivalent back focus. The total lens length is a value obtained by adding the value of the back focus BF to the distance from the first lens surface to the final lens surface. Table 1 shows the relationship between the conditional expressions described above and the examples.

[Numeric data 1]
Unit mm

Surface data Surface number rd nd νd Refractive index temperature coefficient (10 ^-6 / ° C) Specific gravity
1 64.427 0.80 1.90366 31.3
2 37.122 5.47 1.49700 81.5
3 439.731 0.15
4 39.954 4.45 1.60311 60.6
5 341.416 (variable)
6 * 35.794 0.90 1.81600 46.6
7 9.923 4.83
8 -27.878 0.70 1.81600 46.6
9 33.108 0.15
10 21.658 2.70 1.80810 22.8
11 -29.294 0.61
12 -17.917 0.65 1.83481 42.7
13 -99.048 (variable)
14 (Aperture) ∞ 0.40
15 14.586 2.43 1.56384 60.7
16 60.189 2.10
17 11.096 0.90 2.00 100 29.1
18 7.785 3.09 1.49700 81.5
19 481.328 (variable)
20 -22.886 1.69 1.90366 31.3
21 -11.062 0.50 1.69680 55.5
22 -2906.732 (variable)
23 131.892 1.49 1.58913 61.1
24 -22.002 0.80 1.84666 23.8
25 -206.434 0.76
26 11.858 2.93 1.58313 59.4
27 * 62.032 (variable)
28 -58.476 2.00 1.63550 23.9 Plastic lens -115 1.24
29 -30.744 0.30
30 -68.647 1.00 1.53160 55.8 Plastic lens -98 1.01
31 16.058 (variable)
32 -28.287 0.75 1.71300 53.9
33 -50.275 0.15
34 38.419 2.79 1.59522 67.7
35 -232.803 (variable)
36 ∞ 1.00 1.54400 60.0
37 ∞ 0.85
Image plane ∞

Aspheric data 6th surface
K = 0.00000e + 000 A 4 = 6.80977e-007 A 6 = -6.26001e-008 A 8 = 2.60219e-010 A10 = -7.36028e-013

27th page
K = 0.00000e + 000 A 4 = 2.14752e-004

Various data Zoom ratio 7.70
Wide angle Medium Telephoto focal length 17.00 45.29 130.97
F number 3.71 5.63 6.30
Half angle of view (degrees) 38.78 16.78 5.95
Image height 13.66 13.66 13.66
Total lens length 88.79 109.43 136.79
BF (in Air) 9.50 32.69 41.15
Exit pupil position
Distance of -46.37 -62.19 -74.81

d 5 0.65 11.41 33.86
d13 15.79 5.40 0.80
d19 1.53 2.86 3.86
d22 2.68 1.34 0.35
d27 2.35 4.29 1.69
d31 10.81 5.96 9.59
d35 8.00 31.19 39.65

Zoom lens group data group Start surface Focal length
1 1 65.78
2 6 -10.60
3 14 18.30
4 20 -50.31
5 23 26.64
6 28 -32.11
7 32 135.32
8 36 ∞

[Numeric data 2]
Unit mm

Surface data Surface number rd nd νd Refractive index temperature coefficient (10 ^-6 / ° C) Specific gravity
1 69.509 0.80 1.90366 31.3
2 42.094 5.61 1.49700 81.5
3 1251.154 0.15
4 41.681 3.88 1.59522 67.7
5 211.917 (variable)
6 * 38.608 0.90 1.81600 46.6
7 10.436 5.34
8 -36.189 0.70 1.81600 46.6
9 31.633 0.15
10 22.114 3.13 1.80810 22.8
11 -38.243 0.69
12 -21.213 0.65 1.83481 42.7
13 -95.938 (variable)
14 (Aperture) ∞ 0.40
15 15.284 2.50 1.56384 60.7
16 69.825 2.11
17 11.825 0.90 2.00 100 29.1
18 8.236 2.98 1.49700 81.5
19 98.067 (variable)
20 -21.158 1.69 1.90366 31.3
21 -11.361 0.50 1.69680 55.5
22 -75.565 (variable)
23 253.330 1.83 1.58913 61.1
24 -24.588 0.80 1.84666 23.8
25 -311.712 0.76
26 12.926 2.93 1.58313 59.4
27 * 63.858 (variable)
28 -49.211 2.00 1.63550 23.9 Plastic lens -115 1.24
29 -29.869 0.30
30 -32.796 1.00 1.53160 55.8 Plastic lens -98 1.01
31 20.964 (variable)
32 34.715 2.58 1.53160 55.8 Resin lens -98 1.01
33 233.039 (variable)
34 ∞ 1.00 1.54400 60.0
35 ∞ 0.97
Image plane ∞

Aspheric data 6th surface
K = 0.00000e + 000 A 4 = 2.77301e-006 A 6 = -6.57556e-008 A 8 = 2.63256e-010 A10 = -8.10597e-013

27th page
K = 0.00000e + 000 A 4 = 1.52985e-004

Various data Zoom ratio 7.70
Wide angle Medium telephoto focal length 17.00 48.75 130.97
F number 3.59 6.05 6.30
Half angle of view (degrees) 38.78 15.65 5.95
Image height 13.66 13.66 13.66
Total lens length 93.09 114.59 143.09
BF 11.62 39.19 46.30
Exit pupil position
Distance -47.07 -66.48 -80.66

d 5 0.64 10.26 34.94
d13 17.85 5.07 0.74
d19 1.72 3.96 6.12
d22 4.82 2.58 0.43
d27 4.70 5.90 2.17
d31 6.46 2.34 7.11
d33 10.00 37.57 44.68

Zoom lens group data group Start surface Focal length
1 1 69.56
2 6 -11.78
3 14 20.37
4 20 -70.55
5 23 31.81
6 28 -29.81
7 32 76.39
8 34 ∞

[Numeric data 3]
Unit mm

Surface data Surface number rd nd νd Refractive index temperature coefficient (10 ^-6 / ° C) Specific gravity
1 37.869 1.60 1.95375 32.3
2 30.765 6.26 1.49700 81.5
3 1207.216 (variable)
4 28.481 1.10 1.95375 32.3
5 11.436 5.71
6 -56.478 0.80 1.77250 49.6
7 38.511 0.15
8 21.177 4.51 1.92286 18.9
9 186.013 2.00
10 -20.084 1.00 1.77250 49.6
11 -39.929 (variable)
12 (Aperture) ∞ 1.99
13 * 15.036 4.12 1.58313 59.4
14 * -57.380 3.77
15 24.075 0.74 1.83481 42.7
16 15.375 1.81
17 -145.877 0.60 1.90366 31.3
18 11.838 3.43 1.69680 55.5
19 -29.626 (variable)
20 19.861 3.27 1.58144 40.8
21 -18.647 0.80 2.00069 25.5
22 -29.140 (variable)
23 -51.359 2.50 1.63278 23.3 Resin lens -124 1.26
24 -21.106 0.10
25 -22.448 0.80 1.53160 55.8 Resin lens -98 1.01
26 15.788 (variable)
27 * -29.970 2.50 1.76200 40.1
28 -25.948 8.00
29 ∞ 1.00 1.54400 60.0
30 ∞ 0.80
Image plane ∞

Aspherical data 13th surface
K = 0.00000e + 000 A 4 = -3.50649e-005 A 6 = -3.02241e-007 A 8 = 5.41022e-009 A10 = -9.66552e-011

14th page
K = 0.00000e + 000 A 4 = 1.86687e-005 A 6 = -2.58825e-007 A 8 = 3.95584e-009 A10 = -8.29198e-011

27th page
K = 0.00000e + 000 A 4 = -7.82342e-007 A 6 = -1.68373e-008 A 8 = 8.00965e-011

Various data Zoom ratio 4.34
Wide angle Medium Telephoto focal length 18.45 46.95 80.00
F number 3.25 4.48 5.60
Half angle of view (degrees) 36.52 16.22 9.69
Image height 13.66 13.66 13.66
Total lens length 98.76 113.68 139.63
BF 9.45 9.45 9.45
Exit pupil position
Distance -50.72 -74.15 -105.67

d 3 0.70 14.86 28.88
d11 21.49 5.08 2.83
d19 0.20 2.71 3.13
d22 1.70 5.06 3.86
d26 15.68 26.97 41.92

Zoom lens group data group Start surface Focal length
1 1 97.46
2 4 -14.61
3 12 29.17
4 20 24.81
5 23 -24.87
6 27 200.00
7 29 ∞

[Numeric data 4]
Unit mm

Surface data Surface number rd nd νd Refractive index temperature coefficient (10 ^-6 / ° C) Specific gravity
1 66.126 0.80 1.90366 31.3
2 37.944 5.89 1.49700 81.5
3 567.819 0.15
4 38.780 4.96 1.60311 60.6
5 245.175 (variable)
6 * 46.716 0.90 1.81600 46.6
7 9.767 4.76
8 -32.494 0.70 1.81600 46.6
9 34.504 0.15
10 21.172 2.69 1.80810 22.8
11 -31.255 0.63
12 -18.395 0.65 1.83481 42.7
13 -95.283 (variable)
14 (Aperture) ∞ 0.40
15 13.958 1.57 1.56384 60.7
16 66.877 1.48
17 11.364 0.90 2.00 100 29.1
18 7.686 2.92 1.49700 81.5
19 271.351 (variable)
20 -21.613 1.69 1.90366 31.3
21 -10.338 0.50 1.69680 55.5
22 973.291 (variable)
23 129.367 1.43 1.58913 61.1
24 -24.214 0.80 1.84666 23.8
25 -163.780 0.76
26 11.952 2.93 1.58313 59.4
27 * 61.581 (variable)
28 -1068.895 1.00 1.53160 55.8 Plastic lens -98 1.01
29 17.353 (variable)
30 -29.094 0.75 1.71300 53.9
31 -40.698 0.15
32 38.286 2.90 1.59522 67.7
33 -617.555 (variable)
34 ∞ 1.00 1.54400 60.0
35 ∞ 0.51
Image plane ∞

Aspheric data 6th surface
K = 0.00000e + 000 A 4 = 6.92889e-006 A 6 = -5.96199e-008 A 8 = 2.00995e-010 A10 = -4.55158e-013

27th page
K = 0.00000e + 000 A 4 = 2.05158e-004

Various data Zoom ratio 7.70
Wide angle Medium telephoto focal length 17.00 44.95 130.97
F number 3.88 5.96 6.30
Half angle of view (degrees) 38.78 16.90 5.95
Image height 13.66 13.66 13.66
Total lens length 88.59 109.18 136.47
BF 11.16 34.60 41.37
Exit pupil position
Distance -49.50 -64.64 -77.41

d 5 0.64 11.22 35.03
d13 15.63 5.11 0.79
d19 2.36 3.58 4.72
d22 2.71 1.49 0.35
d27 3.19 5.12 1.36
d29 10.43 5.59 10.39
d33 10.00 33.44 40.21

Zoom lens group data group Start surface Focal length
1 1 66.05
2 6 -10.60
3 14 18.26
4 20 -45.86
5 23 25.48
6 28 -32.11
7 30 101.12
8 34 ∞

[Numeric data 5]
Unit mm

Surface data Surface number rd nd νd Refractive index temperature coefficient (10 ^-6 / ° C) Specific gravity
1 41.458 1.40 1.92286 18.9
2 31.248 6.19 1.80 400 46.6
3 164.184 (variable)
4 97.034 0.85 1.88300 40.8
5 16.050 6.02
6 * -97.165 1.00 1.59349 67.0
7 * 36.730 0.30
8 22.453 2.32 1.95906 17.5
9 40.513 (variable)
10 (Aperture) ∞ (Variable)
11 * 15.477 4.57 1.80 400 46.6
12 * -104.798 0.20
13 21.644 3.11 1.88300 40.8
14 -72.621 0.63 2.00069 25.5
15 11.251 3.00
16 ∞ (variable)
17 158.497 2.64 1.80 400 46.6
18 -22.100 (variable)
19 -21.069 1.20 1.53160 55.8 Plastic lens -98 1.01
20 * 129.755 (variable)
21 * -54.610 4.00 1.53160 55.8 Resin lens -98 1.01
22 * -21.654 (variable)
23 ∞ 1.00 1.54400 60.0
24 ∞ 0.81
Image plane ∞

Aspheric data 6th surface
K = 0.00000e + 000 A 4 = -1.95441e-005 A 6 = 1.59027e-007 A 8 = -3.20921e-010

7th page
K = 0.00000e + 000 A 4 = -1.38870e-005 A 6 = 1.82245e-007 A 8 = -2.59333e-010

11th page
K = 0.00000e + 000 A 4 = -2.57321e-005 A 6 = -1.75185e-008 A 8 = -2.57219e-010

12th page
K = 0.00000e + 000 A 4 = 1.89940e-005 A 6 = 6.63351e-010

20th page
K = 0.00000e + 000 A 4 = 2.18513e-005 A 6 = 4.50187e-008 A 8 = -4.14204e-010

21st page
K = 0.00000e + 000 A 4 = -7.61454e-006 A 6 = -2.76692e-008

22nd page
K = 0.00000e + 000 A 4 = 6.13037e-006 A 6 = -7.44418e-008 A 8 = 8.81513e-011

Various data Zoom ratio 2.48
Wide angle Medium Telephoto focal length 18.14 30.19 45.00
F number 2.06 3.00 5.00
Half angle of view (degrees) 33.66 23.99 16.62
Image height 12.08 13.43 13.43
Total lens length 90.17 92.24 97.67
BF 13.96 9.90 3.00
Exit pupil position
Distance -57.14 -79.95 -166.39

d 3 0.80 7.49 15.14
d 9 24.29 16.36 8.51
d10 3.50 -0.13 2.69
d16 4.98 7.09 8.86
d18 2.21 3.42 4.26
d20 3.00 10.68 17.78
d22 12.50 8.44 1.54

Zoom lens group data group Start surface Focal length
1 1 71.37
2 4 -20.09
3 11 30.71
4 17 24.28
5 19 -34.00
6 21 64.77
7 23 ∞

L1 1st lens group L2 2nd lens group L3 3rd lens group L4 4th lens group L5 5th lens group L6 6th lens group L7 7th lens group LM Intermediate group L (N-1) 1st (N-1) Lens group LN Nth lens group

Claims (13)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, an intermediate group including one or more lens groups, and a first lens group having a negative refractive power (N -1) A zoom lens that includes a lens group and an Nth lens group having a positive refractive power, and in which the distance between adjacent lens groups changes during zooming,
The first lens group moves to the object side during zooming from the wide-angle end to the telephoto end,
The (N-1) th lens group has a lens made of resin, moves in the optical axis direction during focusing,
When the lateral magnification of the Nth lens group at the wide angle end is βnw, the back focus at the wide angle end is skw, the focal length of the entire system at the wide angle end is fw, and the total lens length at the wide angle end is Dw,
0.8 <βnw <2.0
0.5 <skw / fw <4.0
2.0 <Dw / fw <11.0
A zoom lens satisfying the following conditional expression: When the focal length of the (N-1) th lens group is f (n-1),
−5.0 <f (n−1) / fw <−1.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the (N-1) th lens group is f (n-1) and the focal length of the Nth lens group is fn,
−1.0 <f (n−1) / fn <−0.1
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the lateral magnification of the (N−1) lens group at the telephoto end is β (n−1) t and the lateral magnification of the Nth lens group at the telephoto end is βnt
−10.0 <(1-β (n−1) t ² ) βnt ² <−1.5
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the average value of the specific gravity of the lens material included in the (N-1) th lens group is Davg (where the specific gravity of the material is the normal temperature of the material used for the lens (15 ° C. to 25 ° C.)). And the mass of pure water at 4 ° C. under the same volume of 101.325 kPa (standard atmospheric pressure).
1.0 <Davg <2.5
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the Nth lens group is fn,
3.0 <fn / skw <30.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the first lens group is f1,
2.0 <f1 / fw <8.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the distance from the image plane at the wide angle end to the exit pupil position is POw,
-4.0 <POw / fw <-1.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.   The zoom lens according to any one of claims 1 to 8, wherein the (N-1) th lens group includes a positive lens made of resin and a negative lens made of resin. The focal length of the negative lens made of resin contained in the (N-1) th lens group is f (n-1) n, and the refractive index temperature coefficient (10 ^-6 / ° C) of the material of the negative lens is dn (n -1) n / dT, the focal length of the positive lens made of resin contained in the (n-1) th lens group is f (n-1) p, and the refractive index temperature coefficient of the positive lens material (10 ^-6 / ° C) is dn (n-1) p / dT,
−50.0 <(1 / f (n−1) n × dn (n−1) n / dT) / (1 / f (n−1) p × dn (n−1) p / dT) <− 1.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.   The intermediate group includes a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power, which are arranged in order from the object side to the image side. The zoom lens according to claim 1, wherein:   The said intermediate | middle group is comprised from the 3rd lens group of positive refractive power and the 4th lens group of positive refractive power arrange | positioned in order from an object side to an image side. The zoom lens according to any one of the above.   An image pickup apparatus comprising: the zoom lens according to claim 1; and a solid-state image pickup device that receives an image formed by the zoom lens.