JP2016014841A - Zoom lens and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens capable of reducing the size of a focus group while ensuring a satisfactory optical performance.SOLUTION: The zoom lens includes in order from the object side: a first lens group GR1 which has a positive refractive power; a second lens group GR2 which has a negative refractive power; a third lens group GR3 which has a positive refractive power; a fourth lens group GR4 which has a positive refractive power; and a fifth lens group GR5 which has a negative refractive power. When zooming, the fifth lens group is fixed, and when the subject distance changes from infinity to proximity, the fourth lens group shifts toward the object side along the optical axis, and the following conditional expression: -0.97<fw/f12w<-0.6...(1)', wherein fw is a focal distance of the lens entire system at a wide angle end; f12w is a combine focal distance of the first lens group and the second lens group at a wide angle end.

Description

  The present disclosure relates to a zoom lens and an imaging apparatus including the zoom lens. Specifically, the present invention relates to a zoom lens that is suitably used for a single-lens reflex camera, a mirrorless camera, a digital still camera, and the like, and covers a standard zoom region, and an imaging apparatus including such a zoom lens.

  In recent years, with the widespread use of single-lens reflex cameras and mirrorless cameras, there is an increasing demand for providing lenses that are compatible with 35 mm version image sensors. Furthermore, the user is expected to provide a lens having a wide open F value in the standard zoom region. In general, the angle of view in the wide-angle end state where the focal length is the shortest includes a range of about 24 mm to 35 mm in terms of 35 mm, and the angle of view in the telephoto end state where the focal length is the longest exceeds 50 mm. The zoom lens is called a standard zoom lens.

  For example, Patent Documents 1 and 2 propose a large-aperture standard zoom lens suitable for a single-lens reflex camera or the like. Further, Patent Document 3 proposes a zoom lens having a five-group configuration including positive, negative, positive, positive, and negative refractive powers in order from the object side.

JP 2007-93976 A JP 2012-123156 A JP 2012-78788 A

  However, in the disclosed example of Patent Document 1, although the standard zoom lens is compatible with the 35 mm version, the F value is only about 2.8. Further, the lens group that moves during focusing is composed of three lenses, and it is difficult to reduce the weight. In the example disclosed in Patent Document 2, the F value is only about 2.8. In the disclosure example of Patent Document 2, since all the five lens groups constituting the zoom lens move during zooming, the weight of the movable group becomes heavy, and the distance from the most object side surface to the imaging surface in the first lens group is increased. The change in distance (optical total length) increases. In the disclosed example of Patent Document 3, the F value is only about 3.5, and the image height is designed to be much smaller than that of the 35 mm plate.

  Therefore, it is desired to develop a zoom lens having a standard zoom region corresponding to a 35 mm version image sensor and having a large aperture with an open F value of about F2.0.

  An object of the present disclosure is to provide a zoom lens capable of reducing the size of a focus group while having a large aperture and high performance and having good optical performance in a standard zoom range, and such a zoom lens. The object is to provide a mounted imaging device.

The zoom lens according to the first aspect of the present disclosure includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a positive refractive power. The lens group, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power, and the first lens group, the second lens group, and the third lens upon zooming When the lens group and each lens group of the fourth lens group move along the optical axis, the fifth lens group is fixed, and the subject distance changes from infinity to close, the fourth lens group It moves to the object side along the axis and satisfies the following conditional expression.
−0.97 <fw / f12w <−0.6 (1) ′
However,
fw: focal length of the entire lens system at the wide angle end,
f12w: The combined focal length of the first lens group and the second lens group at the wide-angle end.

A zoom lens according to a second aspect of the present disclosure includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a positive refractive power. The lens group, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power, and the first lens group, the second lens group, and the third lens upon zooming When the lens group and each lens group of the fourth lens group move along the optical axis, the fifth lens group is fixed, and the subject distance changes from infinity to close, the fourth lens group It moves to the object side along the axis and satisfies the following conditional expression.
-0.97 <fw / f12w <-0.3 (1)
0.1 <β4w <0.4 (2)
However,
fw: focal length of the entire lens system at the wide angle end,
f12w: the combined focal length of the first lens group and the second lens group at the wide-angle end,
β4w: The lateral magnification of the fourth lens group at the wide angle end.

  An imaging device according to a first aspect of the present disclosure includes the zoom lens according to the first aspect of the present disclosure.

  An imaging device according to a second aspect of the present disclosure includes the zoom lens according to the second aspect of the present disclosure.

  In the zoom lens or the imaging apparatus according to the present disclosure, the configuration of each of the first to fifth lens groups is optimized so that the focus group can be downsized while having good optical performance in the standard zoom region. Is planned.

According to the zoom lens or the imaging apparatus of the present disclosure, the configuration of each of the first to fifth lens groups is optimal so that the focus group can be downsized while having good optical performance in the standard zoom region. Therefore, a large aperture and high performance can be achieved, and the focus group can be miniaturized while having good optical performance in the standard zoom region.
Note that the effects described here are not necessarily limited, and may be any of the effects described in the present disclosure.

It is a lens sectional view showing the 1st example of composition of the zoom lens concerning one embodiment of this indication. FIG. 3 is an aberration diagram showing various aberrations at the wide-angle end in Numerical Example 1 in which specific numerical values are applied to the zoom lens illustrated in FIG. 1. FIG. 3 is an aberration diagram illustrating various aberrations at an intermediate focal length in Numerical Example 1 in which specific numerical values are applied to the zoom lens illustrated in FIG. 1. FIG. 3 is an aberration diagram showing various aberrations at the telephoto end in Numerical Example 1 in which specific numerical values are applied to the zoom lens illustrated in FIG. 1. It is a lens sectional view showing the 2nd example of composition of a zoom lens. FIG. 6 is an aberration diagram showing various aberrations at the wide-angle end in Numerical Example 2 in which specific numerical values are applied to the zoom lens illustrated in FIG. 5. FIG. 6 is an aberration diagram illustrating various aberrations at an intermediate focal length in Numerical Example 2 in which specific numerical values are applied to the zoom lens illustrated in FIG. 5. FIG. 6 is an aberration diagram showing various aberrations at the telephoto end in Numerical Example 2 in which specific numerical values are applied to the zoom lens illustrated in FIG. 5. It is a lens sectional view showing the 3rd example of composition of a zoom lens. FIG. 10 is an aberration diagram illustrating various aberrations at the wide-angle end in Numerical Example 3 in which specific numerical values are applied to the zoom lens illustrated in FIG. 9. FIG. 10 is an aberration diagram illustrating various aberrations at an intermediate focal length in Numerical Example 3 in which specific numerical values are applied to the zoom lens illustrated in FIG. 9. FIG. 10 is an aberration diagram illustrating various aberrations at the telephoto end in Numerical Example 3 in which specific numerical values are applied to the zoom lens illustrated in FIG. 9. It is a lens sectional view showing the 4th example of composition of a zoom lens. FIG. 14 is an aberration diagram showing various aberrations at the wide-angle end in Numerical Example 4 in which specific numerical values are applied to the zoom lens illustrated in FIG. 13. FIG. 14 is an aberration diagram illustrating various aberrations at an intermediate focal length in Numerical Example 4 in which specific numerical values are applied to the zoom lens illustrated in FIG. 13. FIG. 14 is an aberration diagram showing various types of aberration at the telephoto end in Numerical Example 4 in which specific numerical values are applied to the zoom lens illustrated in FIG. 13. It is a block diagram which shows the example of 1 structure of an imaging device.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order.
1. 1. Basic configuration of lens Action and effect 3. Application example to imaging device 4. Numerical example of lens Other embodiments

[1. Basic lens configuration]
FIG. 1 illustrates a first configuration example of a zoom lens according to an embodiment of the present disclosure. FIG. 5 shows a second configuration example of the zoom lens. FIG. 9 shows a third configuration example of the zoom lens. FIG. 13 shows a fourth configuration example of the zoom lens. Numerical examples in which specific numerical values are applied to these configuration examples will be described later. In FIG. 1 and the like, Z1 represents an optical axis. Between the zoom lens and the image plane IMG, optical members such as a seal glass for protecting the image sensor and various optical filters FL may be disposed.
Hereinafter, the configuration of the zoom lens according to the present embodiment will be described in association with the configuration example illustrated in FIG. 1 as appropriate, but the technology according to the present disclosure is not limited to the illustrated configuration example.

  As shown in FIG. 1 and the like, the zoom lens according to the present embodiment includes, in order from the object side along the optical axis Z1, the first lens group GR1, the second lens group GR2, and the third lens group GR3. The fourth lens group GR4 and the fifth lens group GR5 are substantially constituted by five lens groups. The first lens group GR1 has a positive refractive power. The second lens group GR2 has a negative refractive power. The third lens group GR3 has a positive refractive power. The fourth lens group GR4 has a positive refractive power. The fifth lens group GR5 has a negative refractive power.

  In FIG. 1 and the like, the upper row indicates the wide angle end, the middle row indicates the intermediate focal length, and the lower row indicates the position of the lens group at the telephoto end. A solid line arrow indicates a moving direction at the time of zooming, and the lens group moves in the direction indicated by the arrow as zooming from the wide-angle end to the telephoto end. As shown in FIG. 1 and the like, the zoom lens according to the present embodiment has the first lens group GR1, the second lens group GR2, the third lens group GR3, and the first lens group upon zooming from the wide angle end to the telephoto end. Each lens group of the four lens groups GR4 moves along the optical axis Z1, and the fifth lens group GR5 is fixed.

  More specifically, upon zooming from the wide-angle end to the telephoto end, the distance between the first lens group GR1 and the second lens group GR2 increases, and the distance between the second lens group GR2 and the third lens group GR3 decreases. The lens groups other than the fifth lens group GR5 move so that the distance between the third lens group GR3 and the fourth lens group GR4 changes and the distance between the fourth lens group GR4 and the fifth lens group GR5 increases. It is preferable. The distance between the third lens group GR3 and the fourth lens group GR4 is preferably increased upon zooming from the wide-angle end to the telephoto end.

  In the zoom lens according to the present embodiment, the fourth lens group GR4 moves to the object side along the optical axis Z1 as a focus group during focusing when the subject distance changes from infinity to close.

  In addition, it is desirable that the zoom lens according to the present embodiment satisfies a predetermined conditional expression described later.

[2. Action / Effect]
Next, functions and effects of the zoom lens according to the present embodiment will be described. In addition, a desirable configuration of the zoom lens according to the present embodiment will be described.
Note that the effects described in the present specification are merely examples and are not limited, and other effects may be obtained.

  The zoom lens according to the present embodiment has a standard zoom region corresponding to a 35 mm version image sensor, and has a large aperture with an open F value of about F2.0 and high performance, which is favorable. The focus group can be miniaturized while having optical performance.

  In the zoom lens according to the present embodiment, as in the basic configuration described above, a desired zoom ratio can be moved small by performing zooming by sharing each lens group of the first lens group GR1 to the fourth lens group GR4. This can be achieved in an amount, which is advantageous for shortening the optical total length.

  Further, by performing focusing with the fourth lens group GR4 located away from the iris, the axial and peripheral light beams pass through the focus group in a state of being separated from each other, so that both aberrations can be corrected respectively. . Furthermore, by making the refractive power of the third lens group GR3 positive, the diverging light beam is guided to the focus group while converging at the third lens group GR3, so that the height of the light beam can be lowered, and the small diameter of the focus group It is advantageous for the conversion. In addition, since the on-axis light beam having an F value of approximately 2.0 becomes substantially parallel light and enters the focus group, fluctuations in optical performance due to focusing can be suppressed.

  In addition, fixing the fifth lens group GR5 is advantageous in at least four respects. First, when the fifth lens group GR5 moves toward the object side on the optical axis from the wide-angle end to the telephoto end (when the fifth lens group GR5 is movable), the side of the fifth lens group GR5 at the telephoto end. The magnification increases, and the change in the optical total length increases. On the other hand, when the fifth lens group GR5 is fixed, a change in the optical total length can be suppressed. Secondly, when the fifth lens group GR5 is movable, the combined positive refractive power from the first lens group GR1 to the fourth lens group GR4 is increased, so that in the first lens group GR1 to the fourth lens group GR4, Becomes a luminous flux brighter than the F value of the entire lens system, which is disadvantageous for correction of spherical aberration. On the other hand, when the fifth lens group GR5 is fixed, high on-axis optical performance can be ensured. Third, by fixing the fifth lens group GR5, the movable group can be reduced in weight. Fourth, by fixing the fifth lens group GR5, the way of the light flux does not change between the wide-angle end and the telephoto end, so that aberration fluctuations can be suppressed.

It is desirable that the zoom lens according to the present embodiment satisfies the following conditional expression (1).
-0.97 <fw / f12w <-0.3 (1)
However,
fw: focal length of the entire lens system at the wide angle end,
f12w: the combined focal length of the first lens group GR1 and the second lens group GR2 at the wide angle end,
β4w: The lateral magnification of the fourth lens group GR1 at the wide angle end.

  Conditional expression (1) is an expression that prescribes a composite focal length of the first lens group GR1 and the second lens group GR2 that is preferable for improving the axial performance at the wide-angle end. When the lower limit of conditional expression (1) is not reached, the combined negative refractive power of the first lens group GR1 and the second lens group GR2 becomes strong, and the spherical aberration becomes too large. In addition, the aperture diameter for securing the necessary F value is increased, and it is difficult to reduce the weight of the focus group, which is disadvantageous for increasing the AF speed. Furthermore, since the back focus becomes too long, the optical total length becomes large, which is not desirable. If the upper limit of conditional expression (1) is exceeded, the negative refractive power of the combination of the first lens group GR1 and the second lens group GR2 becomes weak, and it becomes difficult to ensure the back focus.

  In a single-lens reflex camera, the combined refractive power of the first lens group GR1 and the second lens group GR2 needs to be strongly negative in order to ensure the back focus. By using a mirrorless camera, the back focus to be secured can be further shortened. This suppresses an excessive increase in the negative refractive power of the combination of the first lens group GR1 and the second lens group GR2, which is advantageous for correction of spherical aberration, as well as an aperture diameter and a lens barrel. It is also effective in reducing the outer diameter, reducing the weight of the focus group, that is, increasing the AF (autofocus) speed.

  In addition, it is desirable that conditional expression (1) is satisfied together with conditional expression (2) described later.

In order to further obtain the above effect, it is desirable to set the numerical range of conditional expression (1) to the range of conditional expression (1) ′ below.
−0.97 <fw / f12w <−0.6 (1) ′

In order to further enhance the above effect, it is more desirable to set the numerical range to the range of the following conditional expression (1) ''.
−0.97 <fw / f12w <−0.63 (1) ″

In the zoom lens according to the present embodiment, it is preferable that the following conditional expression (2) is satisfied.
0.1 <β4w <0.4 (2)
However,
β4w: The lateral magnification of the fourth lens group GR4 at the wide-angle end.

  Conditional expression (2) is an expression that defines the lateral magnification of the fourth lens group GR4, which is desirable for reducing the amount of movement of the fourth lens group GR4 during focusing. When the lower limit value of conditional expression (2) is not reached, the positive refractive power of the fourth lens group GR4 becomes strong, so that the focus sensitivity becomes too high, and manufacturing errors and control errors become severe. If the upper limit value of conditional expression (2) is exceeded, the positive refractive power of the fourth lens group GR4 becomes weak, so the amount of movement of the fourth lens group GR4 during focusing becomes too large and the optical total length becomes large. Therefore, it is disadvantageous for downsizing the lens barrel.

In order to further obtain the above effect, it is desirable to set the numerical range of conditional expression (2) to the range of conditional expression (2) ′ below.
0.1 <β4w <0.3 (2) ′

In order to further enhance the above effect, it is more desirable to set the numerical range to the range of the following conditional expression (2) ″.
0.13 <β4w <0.23 (2) ''

In the zoom lens according to the present embodiment, it is preferable that the following conditional expression (3) is satisfied.
0.52 <1 / β5 <0.8 (3)
However,
β5: The lateral magnification of the fifth lens group GR5.

  Conditional expression (3) defines the lateral magnification of the fifth lens group GR5, which is desirable for reducing the size of the lens barrel. If the lower limit value of conditional expression (3) is not reached, the negative refractive power of the fifth lens group GR5 becomes stronger, so that the aberration generated in the first lens group GR1 to the fourth lens group GR4 is excessively enlarged. This is disadvantageous for optical performance. When the upper limit of conditional expression (3) is exceeded, the negative refractive power of the fifth lens group GR5 becomes weak, so the combined positive refractive power from the first lens group GR1 to the fourth lens group GR4 is also weak. This is too disadvantageous for downsizing because the optical total length becomes large. In addition, it becomes difficult to correct the aberrations of the axial and peripheral light beams.

In order to further obtain the above effect, it is desirable to set the numerical range of conditional expression (3) to the range of conditional expression (3) ′ below.
0.55 <1 / β5 <0.75 (3) ′

  Here, in the zoom lens according to the present embodiment, it is desirable that the fourth lens group GR4 is composed of two or less lenses. Since the fourth lens group GR4 is composed of two or less lenses, it is advantageous for reducing the weight of the focus group and is effective for increasing the AF speed. Further, in order to ensure optical performance even if the number of fourth lens groups GR4 serving as a focus group is small, it is desirable that the fourth lens group GR4 includes one positive lens and one negative lens. As a result, chromatic aberration can be corrected effectively, and variation in lateral chromatic aberration due to distance can also be suppressed. In addition, it is desirable that at least one lens surface of the plurality of lens surfaces constituting the fourth lens group GR4 has an aspherical shape. Thereby, aberration fluctuations such as field curvature due to distance can be suppressed.

  Furthermore, in the zoom lens according to the present embodiment, it is desirable that the fifth lens group GR5 is composed of at least one positive lens and at least one negative lens. The positive lens corrects the coma aberration of the peripheral luminous flux, and the negative lens is advantageous for correction of field curvature. In order to further obtain this effect, it is desirable that the fifth lens group GR5 includes negative, positive, and negative lenses in order from the object side. Thereby, in the fifth lens group GR5, since the axial and peripheral light beams pass through the positive lens in a state of being separated from each other, the coma aberration can be effectively corrected.

  Further, in the zoom lens according to the present embodiment, the aperture stop S is disposed between the second lens group GR2 and the third lens group GR3 or inside the third lens group GR3, and the first lens is changed during zooming. It is desirable that the three lens group GR3 and the aperture stop S move integrally. As the aperture stop S moves toward the object side on the optical axis as it goes from the wide-angle end to the telephoto end, the light beam emitted from the second lens group GR2 passes through the aperture stop S without being excessively diverged. This is advantageous in reducing the diameter of the lens barrel.

[3. Application example to imaging device]
FIG. 17 shows a configuration example of the imaging apparatus 100 to which the zoom lens according to the present embodiment is applied. The imaging device 100 is, for example, a digital still camera, and includes a camera block 10, a camera signal processing unit 20, an image processing unit 30, an LCD (Liquid Crystal Display) 40, and an R / W (reader / writer) 50. , A CPU (Central Processing Unit) 60, an input unit 70, and a lens drive control unit 80.

  The camera block 10 bears an imaging function, and includes an optical system including a zoom lens 11 and an imaging element 12 such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The imaging element 12 outputs an imaging signal (image signal) corresponding to the optical image by converting the optical image formed by the zoom lens 11 into an electrical signal. As the zoom lens 11, the zoom lenses 1 to 4 of the respective configuration examples shown in FIGS. 1, 5, 9, and 13 can be applied.

  The camera signal processing unit 20 performs various signal processing such as analog-digital conversion, noise removal, image quality correction, and conversion to luminance / color difference signals on the image signal output from the image sensor 12.

  The image processing unit 30 performs recording and reproduction processing of an image signal, and performs compression encoding / decompression decoding processing of an image signal based on a predetermined image data format, conversion processing of data specifications such as resolution, and the like. It has become.

  The LCD 40 has a function of displaying various data such as an operation state of the user input unit 70 and a photographed image. The R / W 50 performs writing of the image data encoded by the image processing unit 30 to the memory card 1000 and reading of the image data recorded on the memory card 1000. The memory card 1000 is a semiconductor memory that can be attached to and detached from a slot connected to the R / W 50, for example.

  The CPU 60 functions as a control processing unit that controls each circuit block provided in the imaging apparatus 100, and controls each circuit block based on an instruction input signal or the like from the input unit 70. The input unit 70 includes various switches and the like that are operated by a user. The input unit 70 includes, for example, a shutter release button for performing a shutter operation, a selection switch for selecting an operation mode, and the like, and outputs an instruction input signal corresponding to an operation by the user to the CPU 60. ing. The lens drive control unit 80 controls driving of the lenses arranged in the camera block 10 and controls a motor (not shown) that drives each lens of the zoom lens 11 based on a control signal from the CPU 60. It has become.

Hereinafter, an operation in the imaging apparatus 100 will be described.
In a shooting standby state, under the control of the CPU 60, an image signal shot by the camera block 10 is output to the LCD 40 via the camera signal processing unit 20 and displayed as a camera through image. For example, when an instruction input signal for zooming or focusing is input from the input unit 70, the CPU 60 outputs a control signal to the lens drive control unit 80, and the zoom lens 11 is controlled based on the control of the lens drive control unit 80. The predetermined lens moves.

  When a shutter (not shown) of the camera block 10 is operated by an instruction input signal from the input unit 70, the captured image signal is output from the camera signal processing unit 20 to the image processing unit 30 and subjected to compression encoding processing. Converted to digital data in data format. The converted data is output to the R / W 50 and written to the memory card 1000.

  Note that focusing is performed by the lens drive control unit 80 based on a control signal from the CPU 60, for example, when the shutter release button of the input unit 70 is half-pressed or when it is fully pressed for recording (photographing). This is performed by moving a predetermined lens of the zoom lens 11.

  When reproducing the image data recorded on the memory card 1000, predetermined image data is read from the memory card 1000 by the R / W 50 in response to an operation on the input unit 70, and decompressed and decoded by the image processing unit 30. After the processing is performed, the reproduction image signal is output to the LCD 40 and the reproduction image is displayed.

  In the above-described embodiment, an example in which the imaging device is applied to a digital still camera has been described. However, the application range of the imaging device is not limited to a digital still camera, and can be applied to other various imaging devices. It is. For example, the present invention can be applied to a digital single lens reflex camera, a digital non-reflex camera, and a digital video camera. In addition, it can be widely applied as a camera unit of a digital input / output device such as a mobile phone with a camera incorporated therein or an information terminal with a camera incorporated therein. The present invention can also be applied to an interchangeable lens camera.

<4. Numerical Examples of Lens>
Next, specific numerical examples of the zoom lens according to the present embodiment will be described. Here, numerical examples in which specific numerical values are applied to the zoom lenses 1 to 4 of the respective configuration examples shown in FIGS. 1, 5, 9, and 13 will be described.

  In addition, the meanings of symbols shown in the following tables and descriptions are as shown below. “Si” indicates the number of the i-th surface with a sign so as to increase sequentially from the most object side. “Ri” indicates the value (mm) of the paraxial radius of curvature of the i-th surface. “Di” indicates a value (mm) of an interval on the optical axis between the i-th surface and the (i + 1) -th surface. “Ni” indicates the value of the refractive index at the d-line (wavelength 587.6 nm) of the material of the optical element having the i-th surface. “Νi” represents the value of the Abbe number in the d-line of the material of the optical element having the i-th surface. The portion where the value of “ri” is “∞” indicates a flat surface or a diaphragm surface (aperture stop S). The surface marked “STO” in “Si” indicates the aperture stop S. “F” indicates the focal length of the entire lens system, “Fno” indicates the F number, and “ω” indicates the half angle of view.

Some lenses used in each numerical example have an aspheric lens surface. The surface marked “ASP” in “Si” indicates an aspherical surface. The aspheric shape is defined by the following aspheric expression. In each table showing aspherical coefficients, which will be described later, “E-i” represents an exponential expression with a base of 10, that is, “10 ⁻ⁱ ”. For example, “0.12345E-05” represents “ 0.12345 × 10 ⁻⁵ ”.

(Aspherical formula)
x = cy ² / [1+ {1− (1 + κ) c ² y ² } ^1/2 ] + Ay ⁴ + By ⁶ + Cy ⁸ + Dy ¹⁰

here,
x: Sag amount (distance in the optical axis direction from the apex of the lens surface)
y: Height in the direction perpendicular to the optical axis c: Paraxial curvature at the lens apex (reciprocal of paraxial radius of curvature)
κ: conic constant A: fourth-order aspheric coefficient B: sixth-order aspheric coefficient C: eighth-order aspheric coefficient D: tenth-order aspheric coefficient

(Configuration common to each numerical example)
Each of the zoom lenses 1 to 4 to which the following numerical examples are applied has a configuration that satisfies the basic configuration and desirable conditions of the lens described above. That is, in each of the zoom lenses 1 to 4, in order from the object side, the first lens group GR1 having positive refractive power, the second lens group GR2 having negative refractive power, and the third lens having positive refractive power. The lens group GR3, a fourth lens group GR4 having a positive refractive power, and a fifth lens group GR5 having a negative refractive power are substantially constituted by five lens groups.

  In the zoom lenses 1 to 4, the distance between the first lens group GR1 and the second lens group GR2 is increased during zooming from the wide-angle end to the telephoto end, and the second lens group GR2 and the third lens group GR3 are The distance between the third lens group GR3 and the fourth lens group GR4 is changed, and the distance between the fourth lens group GR4 and the fifth lens group GR5 is increased so that the distance between the third lens group GR3 and the fourth lens group GR4 increases. The lens group moves. The distance between the third lens group GR3 and the fourth lens group GR4 increases upon zooming from the wide-angle end to the telephoto end.

  In each of the zoom lenses 1 to 4, the fourth lens group GR4 moves to the object side along the optical axis Z1 as a focus group during focusing when the subject distance changes from infinity to close.

[Numerical Example 1]
Table 1 shows lens data of Numerical Example 1 in which specific numerical values are applied to the zoom lens 1 shown in FIG. In the zoom lens 1, aspheric surfaces are formed on the sixth surface, the ninth surface, the sixteenth surface, the twenty-first surface, the twenty-third surface, the twenty-fifth surface, and the thirty-second surface. The values of the fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients A, B, C, and D along with the values of the conic constant κ are shown in [Table 2].

  [Table 3] shows the values of the focal length f, F number Fno, and half angle of view ω of the entire lens system at the wide angle end, the intermediate focal length, and the telephoto end. In the zoom lens 1, the distance d5 between the first lens group GR1 and the second lens group GR2 changes during zooming from the wide-angle end to the telephoto end. Further, the distance d14 between the second lens group GR2 and the third lens group GR3 changes. Further, the distance d20 between the third lens group GR3 and the fourth lens group GR4 changes. Further, the distance d23 between the fourth lens group GR4 and the fifth lens group GR5 changes. The values of the variable intervals at the wide-angle end, the intermediate focal length, and the telephoto end are shown in [Table 4].

  In the zoom lens 1 shown in FIG. 1, the first lens group GR1 includes a cemented lens including a meniscus negative lens G1 having a convex surface facing the object side and a meniscus positive lens G2 having a convex surface facing the object side. A meniscus positive lens G3 having a convex surface facing the object side is arranged in order from the object side to the image side.

  The second lens group GR2 includes a meniscus negative lens G4 having a convex surface facing the object side, a biconcave negative lens G5, a biconvex positive lens G6, and a meniscus shape having a convex surface facing the image side. The negative lens G7 is arranged in order from the object side to the image side.

  The third lens group GR3 includes a biconvex positive lens G8, and a cemented lens including a biconcave negative lens G9 and a biconvex positive lens G10 arranged in order from the object side to the image side. ing.

  The fourth lens group GR4 includes a cemented lens including a biconvex positive lens G11 and a meniscus negative lens G12 having a convex surface facing the image side.

  The fifth lens group GR5 includes a meniscus negative lens G13 having a convex surface facing the object side, a meniscus negative lens G14 having a convex surface facing the image side, a biconvex positive lens G15, and a convex surface facing the object side. Is arranged in order from the object side to the image side.

  An optical filter FL is disposed between the fifth lens group GR5 and the image plane IMG. The aperture stop S is disposed on the object side of the third lens group GR3 (between the second lens group GR2 and the third lens group GR3) and moves integrally with the third lens group GR3.

  2 to 4 show various aberrations in the numerical value example 1. FIG. 2 shows various aberrations at the wide-angle end, FIG. 3 shows the intermediate focal length, and FIG. 4 shows the various aberrations at the telephoto end. 2 to 4 show spherical aberration, astigmatism (field curvature), and distortion (distortion aberration) as various aberrations. In the aberration diagram of field curvature, a solid line (S) indicates a value on a sagittal image plane, and a broken line (M) indicates a value on a meridional image plane.

  As can be seen from each aberration diagram, the zoom lens 1 according to Numerical Example 1 has excellent imaging performance in which each aberration is well corrected at the wide-angle end, the intermediate focal length, and the telephoto end. Is clear.

[Numerical Example 2]
Table 5 shows lens data of Numerical Example 2 in which specific numerical values are applied to the zoom lens 2 shown in FIG. In the zoom lens 2, aspheric surfaces are formed on the sixth surface, the sixteenth surface, the twenty-first surface, the twenty-third surface, the twenty-fifth surface, and the thirty-second surface. The values of the fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients A, B, C, and D on these aspheric surfaces are shown in [Table 6] together with the value of the conic constant κ.

  [Table 7] shows the values of the focal length f, the F number Fno, and the half angle of view ω of the entire lens system at the wide angle end, the intermediate focal length, and the telephoto end. In the zoom lens 2, the distance d5 between the first lens group GR1 and the second lens group GR2 changes during zooming from the wide-angle end to the telephoto end. Further, the distance d14 between the second lens group GR2 and the third lens group GR3 changes. Further, the distance d20 between the third lens group GR3 and the fourth lens group GR4 changes. Further, the distance d23 between the fourth lens group GR4 and the fifth lens group GR5 changes. The values of the variable intervals at the wide angle end, the intermediate focal length, and the telephoto end are shown in [Table 8].

  In the zoom lens 2 shown in FIG. 5, the first lens group GR1 includes a cemented lens including a meniscus negative lens G1 having a convex surface facing the object side and a meniscus positive lens G2 having a convex surface facing the object side. A meniscus positive lens G3 having a convex surface facing the object side is arranged in order from the object side to the image side.

  The second lens group GR2 includes a meniscus negative lens G4 having a convex surface facing the object side, a biconcave negative lens G5, a biconvex positive lens G6, and a meniscus shape having a convex surface facing the image side. The negative lens G7 is arranged in order from the object side to the image side.

  The third lens group GR3 includes a biconvex positive lens G8, and a cemented lens including a biconcave negative lens G9 and a biconvex positive lens G10 arranged in order from the object side to the image side. ing.

  The fourth lens group GR4 includes a cemented lens including a biconvex positive lens G11 and a meniscus negative lens G12 having a convex surface facing the image side.

  The fifth lens group GR5 includes a meniscus negative lens G13 having a convex surface facing the object side, a biconcave negative lens G14, a biconvex positive lens G15, and a meniscus shape having a convex surface facing the object side. A negative lens G16 is arranged in order from the object side to the image side.

  An optical filter FL is disposed between the fifth lens group GR5 and the image plane IMG. The aperture stop S is disposed on the object side of the third lens group GR3 (between the second lens group GR2 and the third lens group GR3) and moves integrally with the third lens group GR3.

  6 to 8 show various aberrations in the numerical value example 2. FIG. 6 shows various aberrations at the wide-angle end, FIG. 7 shows the intermediate focal length, and FIG. 8 shows the various aberrations at the telephoto end. 6 to 8 show spherical aberration, astigmatism (field curvature), and distortion (distortion aberration) as various aberrations. In the aberration diagram of field curvature, a solid line (S) indicates a value on a sagittal image plane, and a broken line (M) indicates a value on a meridional image plane.

  As can be seen from each aberration diagram, the zoom lens 2 according to Numerical Example 2 has excellent imaging performance with each aberration being corrected well at the wide-angle end, the intermediate focal length, and the telephoto end. Is clear.

[Numerical Example 3]
Table 9 shows lens data of Numerical Example 3 in which specific numerical values are applied to the zoom lens 3 shown in FIG. In the zoom lens 3, aspherical surfaces are formed on the sixth surface, the ninth surface, the fourteenth surface, the twentieth surface, the twenty-second surface, the twenty-fourth surface, and the thirty-first surface. The values of the fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients A, B, C, and D along with the values of the conic constant κ are shown in [Table 10].

  [Table 11] shows the values of the focal length f, the F number Fno, and the half angle of view ω of the entire lens system at the wide angle end, the intermediate focal length, and the telephoto end. In the zoom lens 3, the distance d5 between the first lens group GR1 and the second lens group GR2 changes during zooming from the wide-angle end to the telephoto end. Further, the distance d13 between the second lens group GR2 and the third lens group GR3 changes. Further, the distance d19 between the third lens group GR3 and the fourth lens group GR4 changes. Further, the distance d22 between the fourth lens group GR4 and the fifth lens group GR5 changes. The values of the variable intervals at the wide-angle end, the intermediate focal length, and the telephoto end are shown in [Table 12].

  In the zoom lens 3 shown in FIG. 9, the first lens group GR1 includes a cemented lens including a meniscus negative lens G1 having a convex surface facing the object side and a meniscus positive lens G2 having a convex surface facing the object side. A meniscus positive lens G3 having a convex surface facing the object side is arranged in order from the object side to the image side.

  The second lens group GR2 has a meniscus negative lens G4 having a convex surface facing the object side, a cemented lens composed of a biconcave negative lens G5 and a biconvex positive lens G6, and a convex surface facing the image side. A meniscus negative lens G7 is arranged in order from the object side to the image side.

  The third lens group GR3 includes a biconvex positive lens G8, and a cemented lens including a biconcave negative lens G9 and a biconvex positive lens G10 arranged in order from the object side to the image side. ing.

  The fourth lens group GR4 includes a cemented lens including a biconvex positive lens G11 and a meniscus negative lens G12 having a convex surface facing the image side.

  The fifth lens group GR5 includes a meniscus negative lens G13 having a convex surface facing the object side, a biconcave negative lens G14, a biconvex positive lens G15, and a meniscus shape having a convex surface facing the object side. A negative lens G16 is arranged in order from the object side to the image side.

  An optical filter FL is disposed between the fifth lens group GR5 and the image plane IMG. The aperture stop S is disposed inside the third lens group GR3 and moves integrally with the third lens group GR3.

  10 to 12 show various aberrations in the numerical value example 3. FIG. FIG. 10 shows various aberrations at the wide-angle end, FIG. 11 shows the intermediate focal length, and FIG. 12 shows the various aberrations at the telephoto end. 10 to 12 show spherical aberration, astigmatism (field curvature), and distortion (distortion aberration) as various aberrations. In the aberration diagram of field curvature, a solid line (S) indicates a value on a sagittal image plane, and a broken line (M) indicates a value on a meridional image plane.

  As can be seen from each aberration diagram, the zoom lens 3 according to Numerical Example 3 has excellent imaging performance in which each aberration is well corrected at the wide-angle end, the intermediate focal length, and the telephoto end. Is clear.

[Numerical Example 4]
Table 13 shows lens data of Numerical Example 3 in which specific numerical values are applied to the zoom lens 4 shown in FIG. In the zoom lens 4, aspherical surfaces are formed on the sixth surface, the ninth surface, the sixteenth surface, the twenty-first surface, the twenty-third surface, the twenty-fifth surface, and the thirty-second surface. The values of the fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients A, B, C, and D along with the values of the conic constant κ are shown in [Table 14].

  [Table 15] shows the values of the focal length f, F number Fno, and half angle of view ω of the entire lens system at the wide angle end, the intermediate focal length, and the telephoto end. In the zoom lens 4, the distance d5 between the first lens group GR1 and the second lens group GR2 changes during zooming from the wide-angle end to the telephoto end. Further, the distance d14 between the second lens group GR2 and the third lens group GR3 changes. Further, the distance d20 between the third lens group GR3 and the fourth lens group GR4 changes. Further, the distance d23 between the fourth lens group GR4 and the fifth lens group GR5 changes. The values of the variable intervals at the wide angle end, the intermediate focal length, and the telephoto end are shown in [Table 16].

  In the zoom lens 4 shown in FIG. 13, the first lens group GR1 includes a cemented lens including a meniscus negative lens G1 having a convex surface facing the object side and a meniscus positive lens G2 having a convex surface facing the object side. A meniscus positive lens G3 having a convex surface facing the object side is arranged in order from the object side to the image side.

  The second lens group GR2 includes a meniscus negative lens G4 having a convex surface facing the object side, a biconcave negative lens G5, a biconvex positive lens G6, and a meniscus shape having a convex surface facing the image side. The negative lens G7 is arranged in order from the object side to the image side.

  The third lens group GR3 includes a biconvex positive lens G8, a cemented lens including a meniscus negative lens G9 having a convex surface facing the object side, and a meniscus positive lens G10 having a convex surface facing the object side. Arranged in order from the object side to the image side.

  The fourth lens group GR4 includes a cemented lens including a biconvex positive lens G11 and a meniscus negative lens G12 having a convex surface facing the image side.

  The fifth lens group GR5 includes a biconcave negative lens G13, a meniscus negative lens G14 having a convex surface facing the object side, a biconvex positive lens G15, and a meniscus shape having a convex surface facing the object side. A negative lens G16 is arranged in order from the object side to the image side.

  An optical filter FL is disposed between the fifth lens group GR5 and the image plane IMG. The aperture stop S is disposed on the object side of the third lens group GR3 (between the second lens group GR2 and the third lens group GR3) and moves integrally with the third lens group GR3.

  14 to 16 show various aberrations in Numerical Example 4. FIG. FIG. 14 shows various aberrations at the wide-angle end, FIG. 15 shows the intermediate focal length, and FIG. 16 shows the various aberrations at the telephoto end. 14 to 16 show spherical aberration, astigmatism (field curvature), and distortion (distortion aberration) as various aberrations. In the aberration diagram of field curvature, a solid line (S) indicates a value on a sagittal image plane, and a broken line (M) indicates a value on a meridional image plane.

  As can be seen from the respective aberration diagrams, the zoom lens 4 according to Numerical Example 4 has excellent imaging performance in which each aberration is well corrected at the wide-angle end, the intermediate focal length, and the telephoto end. Is clear.

[Other numerical data of each example]
[Table 17] shows a summary of values relating to the above-described conditional expressions for each numerical example. As can be seen from [Table 17], for each conditional expression, the value of each numerical example is within the numerical range.

<5. Other Embodiments>
The technology according to the present disclosure is not limited to the description of the above-described embodiments and examples, and various modifications can be made.
For example, the shapes and numerical values of the respective parts shown in the numerical examples are merely examples of embodiments for carrying out the present technology, and the technical scope of the present technology is interpreted in a limited manner by these. There should be no such thing.

  In the above-described embodiments and examples, the configuration including substantially five lens groups has been described. However, the configuration may further include a lens having substantially no refractive power.

For example, this technique can take the following composition.
[1]
From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having a positive refractive power;
A fifth lens group having negative refractive power,
During zooming, the first lens group, the second lens group, the third lens group, and the fourth lens group move along the optical axis, and the fifth lens group is fixed. ,
When the subject distance changes from infinity to close, the fourth lens group moves to the object side along the optical axis,
A zoom lens that satisfies the following conditional expressions.
−0.97 <fw / f12w <−0.6 (1) ′
However,
fw: focal length of the entire lens system at the wide angle end,
f12w: The combined focal length of the first lens group and the second lens group at the wide-angle end.
[2]
The zoom lens according to [1], further satisfying the following conditional expression:
0.1 <β4w <0.4 (2)
However,
β4w: The lateral magnification of the fourth lens group at the wide angle end.
[3]
The zoom lens according to [1] or [2], further satisfying the following conditional expression:
0.52 <1 / β5 <0.8 (3)
However,
β5: The lateral magnification of the fifth lens group.
[4]
The zoom lens according to any one of [1] to [3], wherein the number of lenses constituting the fourth lens group is two or less.
[5]
The zoom lens according to any one of [1] to [4], wherein the fifth lens group includes at least one positive lens and at least one negative lens.
[6]
An aperture stop is disposed between the second lens group and the third lens group or inside the third lens group, and the third lens group and the aperture stop move integrally during zooming. The zoom lens according to any one of [1] to [5].
[7]
When the lens position changes from the wide-angle end state to the telephoto end state,
An interval between the first lens group and the second lens group is increased;
An interval between the second lens group and the third lens group is reduced;
The distance between the third lens group and the fourth lens group changes,
The zoom lens according to any one of [1] to [5], wherein an interval between the fourth lens group and the fifth lens group is increased.
[8]
The zoom lens according to any one of [1] to [7], further including a lens having substantially no refractive power.
[9]
From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having a positive refractive power;
A fifth lens group having negative refractive power,
During zooming, the first lens group, the second lens group, the third lens group, and the fourth lens group move along the optical axis, and the fifth lens group is fixed. ,
When the subject distance changes from infinity to close, the fourth lens group moves to the object side along the optical axis,
A zoom lens that satisfies the following conditional expressions.
-0.97 <fw / f12w <-0.3 (1)
0.1 <β4w <0.4 (2)
However,
fw: focal length of the entire lens system at the wide angle end,
f12w: the combined focal length of the first lens group and the second lens group at the wide-angle end,
β4w: The lateral magnification of the fourth lens group at the wide angle end.
[10]
The zoom lens according to [9], further satisfying the following conditional expression:
0.52 <1 / β5 <0.8 (3)
However,
β5: The lateral magnification of the fifth lens group.
[11]
The zoom lens according to [9] or [10], wherein the number of lenses constituting the fourth lens group is two or less.
[12]
The zoom lens according to any one of [9] to [11], wherein the fifth lens group includes at least one positive lens and at least one negative lens.
[13]
An aperture stop is disposed between the second lens group and the third lens group or inside the third lens group, and the third lens group and the aperture stop move integrally during zooming. [9] The zoom lens according to any one of [12].
[14]
When the lens position changes from the wide-angle end state to the telephoto end state,
An interval between the first lens group and the second lens group is increased;
An interval between the second lens group and the third lens group is reduced;
The distance between the third lens group and the fourth lens group changes,
The zoom lens according to any one of [9] to [13], wherein an interval between the fourth lens group and the fifth lens group is increased.
[15]
The zoom lens according to any one of [9] to [14], further including a lens having substantially no refractive power.
[16]
A zoom lens, and an image sensor that outputs an image signal corresponding to an optical image formed by the zoom lens,
The zoom lens is
From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having a positive refractive power;
A fifth lens group having negative refractive power,
During zooming, the first lens group, the second lens group, the third lens group, and the fourth lens group move along the optical axis, and the fifth lens group is fixed. ,
When the subject distance changes from infinity to close, the fourth lens group moves to the object side along the optical axis,
An imaging apparatus that satisfies the following conditional expression.
−0.97 <fw / f12w <−0.6 (1) ′
However,
fw: focal length of the entire lens system at the wide angle end,
f12w: The combined focal length of the first lens group and the second lens group at the wide-angle end.
[17]
The zoom device according to [16], wherein the zoom lens further includes a lens having substantially no refractive power.
[18]
A zoom lens, and an image sensor that outputs an image signal corresponding to an optical image formed by the zoom lens,
The zoom lens is
From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having a positive refractive power;
A fifth lens group having negative refractive power,
During zooming, the first lens group, the second lens group, the third lens group, and the fourth lens group move along the optical axis, and the fifth lens group is fixed. ,
When the subject distance changes from infinity to close, the fourth lens group moves to the object side along the optical axis,
An imaging apparatus that satisfies the following conditional expression.
-0.97 <fw / f12w <-0.3 (1)
0.1 <β4w <0.4 (2)
However,
fw: focal length of the entire lens system at the wide angle end,
f12w: the combined focal length of the first lens group and the second lens group at the wide-angle end,
β4w: The lateral magnification of the fourth lens group at the wide angle end.
[19]
The zoom device according to [18], wherein the zoom lens further includes a lens having substantially no refractive power.

GR1: First lens group, GR2: Second lens group, GR3: Third lens group, GR4: Fourth lens group, GR5: Fifth lens group, S: Aperture stop, Z1: Optical axis, 1-4: Zoom Lenses, 10 ... Camera block, 11 ... Zoom lens, 12 ... Image sensor, 20 ... Camera signal processing unit, 30 ... Image processing unit, 40 ... LCD, 50 ... R / W (reader / writer), 60 ... CPU, 70 DESCRIPTION OF SYMBOLS ... Input part, 80 ... Lens drive control part, 100 ... Imaging device, 1000 ... Memory card IMG ... Image surface, FL ... Optical filter.

Claims (15)

From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having a positive refractive power;
A fifth lens group having negative refractive power,
During zooming, the first lens group, the second lens group, the third lens group, and the fourth lens group move along the optical axis, and the fifth lens group is fixed. ,
When the subject distance changes from infinity to close, the fourth lens group moves to the object side along the optical axis,
A zoom lens that satisfies the following conditional expressions.
−0.97 <fw / f12w <−0.6 (1) ′
However,
fw: focal length of the entire lens system at the wide angle end,
f12w: The combined focal length of the first lens group and the second lens group at the wide-angle end. The zoom lens according to claim 1, further satisfying the following conditional expression.
0.1 <β4w <0.4 (2)
However,
β4w: The lateral magnification of the fourth lens group at the wide angle end. The zoom lens according to claim 1, further satisfying the following conditional expression.
0.52 <1 / β5 <0.8 (3)
However,
β5: The lateral magnification of the fifth lens group. The zoom lens according to claim 1, wherein the number of lenses constituting the fourth lens group is two or less. The zoom lens according to claim 1, wherein the fifth lens group includes at least one positive lens and at least one negative lens. An aperture stop is disposed between the second lens group and the third lens group or inside the third lens group, and the third lens group and the aperture stop move together during zooming. Item 4. The zoom lens according to Item 1. When the lens position changes from the wide-angle end state to the telephoto end state,
An interval between the first lens group and the second lens group is increased;
An interval between the second lens group and the third lens group is reduced;
The distance between the third lens group and the fourth lens group changes,
The zoom lens according to claim 1, wherein an interval between the fourth lens group and the fifth lens group is increased. From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having a positive refractive power;
A fifth lens group having negative refractive power,
During zooming, the first lens group, the second lens group, the third lens group, and the fourth lens group move along the optical axis, and the fifth lens group is fixed. ,
When the subject distance changes from infinity to close, the fourth lens group moves to the object side along the optical axis,
A zoom lens that satisfies the following conditional expressions.
-0.97 <fw / f12w <-0.3 (1)
0.1 <β4w <0.4 (2)
However,
fw: focal length of the entire lens system at the wide angle end,
f12w: the combined focal length of the first lens group and the second lens group at the wide-angle end,
β4w: The lateral magnification of the fourth lens group at the wide angle end. The zoom lens according to claim 8, further satisfying the following conditional expression.
0.52 <1 / β5 <0.8 (3)
However,
β5: The lateral magnification of the fifth lens group. The zoom lens according to claim 8, wherein the number of lenses constituting the fourth lens group is two or less. The zoom lens according to claim 8, wherein the fifth lens group includes at least one positive lens and at least one negative lens. An aperture stop is disposed between the second lens group and the third lens group or inside the third lens group, and the third lens group and the aperture stop move together during zooming. Item 9. The zoom lens according to Item 8. When the lens position changes from the wide-angle end state to the telephoto end state,
An interval between the first lens group and the second lens group is increased;
An interval between the second lens group and the third lens group is reduced;
The distance between the third lens group and the fourth lens group changes,
The zoom lens according to claim 8, wherein an interval between the fourth lens group and the fifth lens group is increased. A zoom lens, and an image sensor that outputs an image signal corresponding to an optical image formed by the zoom lens,
The zoom lens is
From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having a positive refractive power;
A fifth lens group having negative refractive power,
During zooming, the first lens group, the second lens group, the third lens group, and the fourth lens group move along the optical axis, and the fifth lens group is fixed. ,
When the subject distance changes from infinity to close, the fourth lens group moves to the object side along the optical axis,
An imaging apparatus that satisfies the following conditional expression.
−0.97 <fw / f12w <−0.6 (1) ′
However,
fw: focal length of the entire lens system at the wide angle end,
f12w: The combined focal length of the first lens group and the second lens group at the wide-angle end. A zoom lens, and an image sensor that outputs an image signal corresponding to an optical image formed by the zoom lens,
The zoom lens is
From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having a positive refractive power;
A fifth lens group having negative refractive power,
During zooming, the first lens group, the second lens group, the third lens group, and the fourth lens group move along the optical axis, and the fifth lens group is fixed. ,
When the subject distance changes from infinity to close, the fourth lens group moves to the object side along the optical axis,
An imaging apparatus that satisfies the following conditional expression.
-0.97 <fw / f12w <-0.3 (1)
0.1 <β4w <0.4 (2)
However,
fw: focal length of the entire lens system at the wide angle end,
f12w: the combined focal length of the first lens group and the second lens group at the wide-angle end,
β4w: The lateral magnification of the fourth lens group at the wide angle end.

Images