JP6696780B2 - Zoom lens and imaging device - Google Patents

Description

  The present invention relates to a zoom lens suitable for an image pickup apparatus equipped with a solid-state image pickup element such as CCD or CMOS.

  Imaging devices equipped with solid-state imaging devices such as CCDs and COMSs, such as single-lens reflex cameras, digital still cameras, video cameras, and surveillance cameras, are rapidly becoming widespread. Along with this, a large number of zoom lenses that can be used in image pickup devices equipped with solid-state image pickup devices such as CCDs and CMOSs have been proposed (see, for example, Patent Documents 1 to 3).

JP, 2005-082068, A JP, 2005-040982, A Japanese Patent No. 4027343

  In recent years, the number of pixels and the sensitivity of solid-state image pickup devices have increased, and a high-resolution and bright photographing lens corresponding to a solid-state image pickup device of 8 million pixels or more has been demanded. Further, as the size of the image pickup apparatus has been reduced, it has been desired to reduce the size and weight of the taking lens. Furthermore, it can be installed in imaging devices such as video cameras and surveillance cameras that are used day and night, and it has high performance not only in the visible light range but also in a wide range of wavelengths including the near infrared range. There is also a need for a large zoom lens.

  The zoom lenses described in Patent Documents 1 and 2 are both zoom lenses having a lens group configuration in which lens groups having negative and positive refractive powers are arranged in order from the object side. Since the zoom lens described in the patent document has a two-group configuration, the aberration correction capability that can be applied to a solid-state image sensor whose number of pixels is increasing more and more in recent years is not sufficient.

  The zoom lens described in Patent Document 3 is a zoom lens having a lens group configuration of a type in which lens groups having negative, positive, and positive refractive powers are arranged in order from the object side. In this zoom lens, the focal lengths of the first lens group, the second lens group, and the third lens group are appropriately set in order to obtain optical performance that can be applied to a solid-state image sensor with high pixels and high sensitivity. But not the problem.

  An image pickup apparatus including a solid-state image pickup element with high pixel count and high sensitivity has a problem that deterioration of image quality is likely to occur even if a slight aberration, which has not been a problem in the past, occurs.

  The present invention, in order to solve the problems caused by the above-described conventional technology, has a simple structure, a large aperture ratio, high pixels, and high optical performance that can be applied to a solid-state imaging device with high sensitivity. In particular, it is an object of the present invention to provide a small-sized zoom lens capable of excellently correcting various aberrations generated for light having a wide range of wavelengths from the visible light region to the near infrared region over the entire zoom range. To do. Further, it is another object of the present invention to provide a high-performance image pickup device capable of obtaining a good image regardless of day or night.

In order to solve the problems described above and achieve the object, a zoom lens according to the present invention includes a first lens group having a negative refractive power and a second lens having a positive refractive power, which are sequentially arranged from the object side. Lens group and a third lens group, and at least the first lens group and the second lens group are moved along the optical axis to change the distance between the lens groups on the optical axis to obtain a wide-angle lens. In the zoom lens that performs zooming from the end to the telephoto end, the third lens group includes at least one positive lens and at least one negative lens, and satisfies the following conditional expression. Characterize.
(1) 1.2 ≦ | f1 / fw | ≦ 2.5
(2) 2.0 ≦ f23w / fw ≦ 3.4
Here, f1 is the focal length of the first lens group, fw is the focal length of the entire lens system at the wide-angle end when the object is focused at infinity, and f23w is the second lens group when the object is focused at infinity at the wide-angle end. The composite focal length with the said 3rd lens group is shown.

  According to the present invention, with a simple structure, a large aperture ratio, high pixels, and high optical performance that can be applied to a solid-state imaging device with improved sensitivity, particularly in the visible light range to the near infrared range. It is possible to provide a small-sized zoom lens capable of satisfactorily correcting various aberrations generated with respect to light of a wide range of wavelengths over the entire zoom range.

  Further, in the zoom lens according to the present invention, in the above invention, an aperture stop is arranged between the first lens group and the second lens group, and the aperture stop and the third lens group are from a wide-angle end to a telephoto end. It is characterized in that it is fixed when the magnification is changed to.

  According to the present invention, since the aperture stop and the third lens group are fixed even during zooming, simplification of the zooming mechanism can be achieved, and the total length of the lens system can be kept short.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(3) 10 ≦ | f3 / fw | ≦ 200
However, f3 indicates the focal length of the third lens group.

  According to the present invention, it is possible to provide a smaller zoom lens having high optical performance.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(4) 1.1 ≦ | f23w / f1 | ≦ 2.1

  According to the present invention, the optical performance can be further improved while keeping the overall length of the lens system short.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(5) 5.0 ≦ | νd3P−νd3n |
Here, νd3P is the Abbe number for the d-line of at least one positive lens included in the third lens group, and νd3n is the Abbe number for the d-line of at least one negative lens included in the third lens group. Show.

  According to the present invention, in the third lens group, axial chromatic aberration and lateral chromatic aberration with respect to light in a wide wavelength range can be favorably corrected over the entire zoom range.

Further, the zoom lens according to the present invention is characterized in that, in the above-mentioned invention, a positive lens is arranged on the most object side of the second lens group, and the following conditional expression is satisfied.
(6) 65.0 ≦ νd2P_ave
However, νd2P_ave represents an average value of Abbe numbers for d lines of all positive lenses included in the second lens group.

  According to the present invention, in the second lens group, it is possible to satisfactorily correct axial chromatic aberration and lateral chromatic aberration with respect to light having a wavelength from the visible light region to the near infrared region over the entire zoom range.

Furthermore, in the zoom lens according to the present invention, in the above invention, the second lens group includes at least one negative lens, and the following conditional expression is satisfied.
(7) 0.000 ≦ PCt_2n_i− (0.546 + 0.00467 × νd_2n_i)
Here, PCt_2n_i represents a partial dispersion ratio of at least one negative lens included in the second lens group with respect to C line and t line, and νd_2n_i represents an Abbe number of the negative lens for which the value of PCt_2n_i was calculated with respect to d line. ..

  According to the present invention, in the second lens group, axial chromatic aberration and lateral chromatic aberration with respect to light in a wavelength range including the near infrared range from the C line to the t line can be corrected well over the entire zoom range. it can.

Further, in the zoom lens according to the present invention, in the above invention, the first lens group includes at least one positive lens and at least two negative lenses, and satisfies the following conditional expression. Characterize.
(8) νd1p ≦ 40.0
(9) 0.000≤PCt_1n_i- (0.546 + 0.00467 × νd_1n_i)
Where νd1p is the Abbe number of at least one positive lens included in the first lens group with respect to the d-line, and PCt_1n_i is the C-line and t-line of at least one negative lens included in the first lens group. The partial dispersion ratio, νd_1n_i, indicates the Abbe number for the d-line of the negative lens for which the value of PCt_1n_i has been calculated.

  According to the present invention, in the first lens group, axial chromatic aberration and lateral chromatic aberration with respect to light in a wavelength range including the near infrared range from the C line to the t line can be corrected well over the entire zoom range. it can.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(10) 0.000 ≦ PCt — 3n_i− (0.546 + 0.00467 × νd — 3n_i)
Here, PCt_3n_i represents a partial dispersion ratio of at least one negative lens included in the third lens group with respect to C line and t line, and νd_3n_i represents an Abbe number of the negative lens for which the value of PCt_3n_i was calculated with respect to d line. ..

  According to the present invention, in the third lens group, axial chromatic aberration and lateral chromatic aberration can be favorably corrected for light in a wavelength range including the near infrared range from the C line to the t line in the entire zoom range. it can.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(11) 0.4 ≦ | f1 / f2 | ≦ 1.1
However, f2 represents the focal length of the second lens group.

  According to the present invention, a bright lens system can be obtained, and the amount of movement of the first lens group that accompanies zooming can be appropriately set, and astigmatism and field curvature associated with zooming can be suppressed. be able to.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(12) 0.2 ≦ | X2 / f2 | ≦ 0.9
However, X2 represents the amount of movement of the second lens group during zooming from the wide-angle end to the telephoto end, and f2 represents the focal length of the second lens group.

  According to the present invention, the amount of movement of the second lens group and the refractive power of the second lens group at the time of zooming are appropriately set to appropriately correct variations in spherical aberration and field curvature during zooming. be able to.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(13) 1.1 ≦ f23t / ft ≦ 2.8
Here, f23t is a combined focal length of the second lens group and the third lens group in the infinity object focused state at the telephoto end, and ft is a focal length of the entire lens system in the infinity object focused state at the telephoto end. Show.

  According to the present invention, the combined focal length of the second lens unit and the third lens unit in the infinity object-focused state at the telephoto end is appropriately set so that the infinity object is focused at the telephoto end of the lens system. It is possible to appropriately correct the spherical aberration, the coma aberration, and the curvature of field that occur.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(14) 3.2 ≦ | f3 / f2 | ≦ 80
However, f2 indicates the focal length of the second lens group, and f3 indicates the focal length of the third lens group.

  According to the present invention, it is possible to effectively suppress astigmatism and field curvature that occur with the movement of the second lens group during zooming.

  An image pickup apparatus according to the present invention is characterized by including the zoom lens according to the above invention, and a solid-state image pickup element that converts an optical image formed by the zoom lens into an electrical signal.

  According to the present invention, it is possible to provide a high-performance imaging device capable of obtaining a good image regardless of day or night.

  According to the present invention, with a simple structure, a large aperture ratio, high pixels, and high optical performance that can be applied to a solid-state imaging device with improved sensitivity, particularly in the visible light range to the near infrared range. It is possible to provide a small-sized zoom lens capable of satisfactorily correcting various aberrations generated with respect to light of a wide range of wavelengths over the entire zoom range.

  Further, according to the present invention, it is possible to provide a high-performance image pickup apparatus capable of obtaining a good image regardless of day or night.

It is a graph for demonstrating the abnormal dispersion property with respect to C line and t line. 3 is a cross-sectional view taken along the optical axis showing the configuration of the zoom lens according to Example 1. FIG. FIG. 6 is a diagram of various types of aberration of the zoom lens according to the first example. 6 is a cross-sectional view taken along the optical axis showing the configuration of the zoom lens according to Example 2. FIG. FIG. 9 is a diagram of various types of aberration of the zoom lens according to the second example. FIG. 6 is a sectional view taken along the optical axis showing the configuration of a zoom lens according to Example 3; FIG. 9 is a diagram of various types of aberration of the zoom lens according to the third example. FIG. 8 is a cross-sectional view taken along the optical axis, showing the configuration of the zoom lens according to Example 4; FIG. 9 is a diagram of various types of aberration of the zoom lens according to the fourth example. FIG. 9 is a cross-sectional view taken along the optical axis showing the configuration of the zoom lens according to example 5; FIG. 13 is a diagram of various types of aberration of the zoom lens according to the fifth example. FIG. 9 is a cross-sectional view taken along the optical axis showing the configuration of the zoom lens according to example 6; FIG. 16 is a diagram of various types of aberration of the zoom lens according to the sixth example. FIG. 11 is a cross-sectional view taken along the optical axis, showing the configuration of the zoom lens according to Example 7; FIG. 16 is a diagram of various types of aberration of the zoom lens according to the example 7; FIG. 16 is a cross-sectional view taken along the optical axis, showing the configuration of the zoom lens according to Example 8; FIG. 16 is a diagram of various types of aberration of the zoom lens according to the example 8; It is a figure which shows an example of the imaging device provided with the zoom lens concerning this invention.

  Hereinafter, preferred embodiments of a zoom lens and an image pickup apparatus according to the present invention will be described in detail.

  In an image pickup apparatus including a solid-state image pickup element with high pixels and high sensitivity, image quality is likely to be deteriorated even if a slight aberration, which has not been a problem in the past, occurs. Therefore, in the present invention, even though the image pickup apparatus has a simple structure, a large aperture ratio, a high pixel count, and a solid-state image pickup element with high sensitivity, image quality is not deteriorated and high optical performance is achieved. The objective is to provide a zoom lens with high performance. Especially, it can be used for imaging devices such as surveillance cameras that are used day and night, and all the aberrations that occur with respect to light of a wide range of wavelengths not only in the visible light region but also in the near infrared region are fully zoomed. It is an object of the present invention to provide a zoom lens having high optical performance, which is capable of excellent correction over a range. Therefore, in order to achieve such an object, the present invention sets various conditions as described below.

  A zoom lens according to the present invention includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive or negative refractive power, which are arranged in order from the object side. And a lens group. Then, at least the first lens group and the second lens group are moved along the optical axis to change the distance between the lens groups on the optical axis, thereby varying the magnification from the wide-angle end to the telephoto end. Further, by moving the first lens group along the optical axis, focusing from the infinity object focused state to the closest object focused state is performed.

  In the present invention, by providing the third lens group on the image side of the second lens group, a higher aberration correction effect can be obtained, and it is possible to realize a zoom lens having an extremely high resolution. The third lens group includes at least one positive lens and at least one negative lens. The third lens group needs to include at least one positive lens and at least one negative lens. As long as this requirement is satisfied, a configuration with multiple positive lenses and one negative lens, one positive lens and multiple negative lenses, or multiple positive lenses and multiple negative lenses is provided. May be. Since the third lens group includes at least one positive lens and at least one negative lens, the spherical aberration and the image surface can be obtained by the positive refractive power of the positive lens and the negative refractive power of the negative lens. By correcting the curvature, the axial chromatic aberration, and the chromatic aberration of magnification, it is possible to balance the various aberrations of the central and peripheral image heights.

  In the present invention, the substantial number of lenses is counted excluding an optical filter or a plane parallel plate having almost no refracting power, and a lens having a long focal length having almost no aberration correction capability. Further, a compound lens in which an aspherical surface is formed on one surface or both surfaces by adhering an aspherical resin or film to a spherical lens is considered to be one lens. A cemented lens in which two lenses are cemented is considered to be two lenses.

In the zoom lens according to the present invention, the focal length of the first lens unit is f1, the focal length of the entire lens system at infinity at the wide-angle end is fw, and the object at infinity at the wide-angle end is When the combined focal length of the second lens group and the third lens group in the focused state is f23w, it is preferable to satisfy the following conditional expression.
(1) 1.2 ≦ | f1 / fw | ≦ 2.5
(2) 2.0 ≦ f23w / fw ≦ 3.4

  By satisfying conditional expressions (1) and (2), it has a simple structure, yet has a large aperture ratio and high optical performance compatible with a high-pixel solid-state imaging device. It is possible to realize a small-sized zoom lens capable of satisfactorily correcting various aberrations generated with respect to light having a wide range of wavelengths up to the outer range over the entire zoom range.

  Conditional expression (1) defines the absolute value of the ratio between the focal length of the entire lens system at the time of focusing on infinity at the wide-angle end and the focal length of the first lens group. By satisfying conditional expression (1), the focal length of the first lens group can be appropriately set, spherical aberration and field curvature can be appropriately corrected, and a bright lens system can be obtained.

  If the lower limit of conditional expression (1) is not reached, the focal length of the first lens group will become too short, and spherical aberration and field curvature will become noticeable in the first lens group, providing bright and good optical performance. It becomes difficult to realize a lens system. On the other hand, when the upper limit of conditional expression (1) is exceeded, the focal length of the first lens group becomes too long, correction of each aberration is insufficient, and the lens aperture increases and the total lens length increases, resulting in a small size. Therefore, it becomes difficult to obtain a high-performance lens system.

If the above conditional expression (1) satisfies the following range, a more preferable effect can be expected.
(1a) 1.3 ≦ | f1 / fw | ≦ 2.2

Further, if the conditional expression (1a) satisfies the following range, a further preferable effect can be expected.
(1b) 1.5 ≦ | f1 / fw | ≦ 2.0

  Further, the conditional expression (2) is the focal length of the entire lens system at the wide-angle end when focused on infinity, and the combined focal length of the second lens group and the third lens group at the wide-angle end when the object is focused at infinity. It defines the ratio with. By satisfying conditional expression (2), the composite focal length of the second lens group and the third lens group in the in-focus state of the object at infinity at the wide-angle end is appropriately set, and the lens system is compact and bright at the wide-angle end. It is possible to properly correct spherical aberration, coma, field curvature, and axial chromatic aberration.

  If the lower limit of conditional expression (2) is not reached, the combined focal length of the second lens unit and the third lens unit in the in-focus state of the object at infinity at the wide-angle end becomes too short, resulting in spherical aberration and coma aberration at the wide-angle end. However, since the curvature of field is excessively corrected, it becomes difficult to perform appropriate aberration correction. On the other hand, when the upper limit of conditional expression (2) is exceeded, the combined focal length of the second lens unit and the third lens unit in the object-focused state at infinity at the wide-angle end becomes too long, and spherical aberration at the wide-angle end, Coma aberration, field curvature, and axial chromatic aberration are insufficiently corrected, and the overall length of the lens system becomes long, making it difficult to obtain good optical performance in a small size.

It should be noted that if the conditional expression (2) satisfies the following range, a more preferable effect can be expected.
(2a) 2.2 ≦ f23w / fw ≦ 3.3

Further, if the conditional expression (2a) satisfies the following range, a further preferable effect can be expected.
(2b) 2.4 ≦ f23w / fw ≦ 2.7

  Further, in the zoom lens according to the present invention, the aperture stop is arranged between the first lens group and the second lens group. Then, it is preferable that the aperture stop and the third lens group be fixed during zooming from the wide-angle end to the telephoto end. By doing so, only the first lens group and the second lens group move during zooming, the zooming mechanism can be simplified, and the overall length of the lens system can be kept short. ..

Further, in the zoom lens according to the present invention, when the focal length of the third lens group is f3 and the focal length of the entire lens system at infinity at the wide angle end is fw, the following conditional expression must be satisfied. Is preferred.
(3) 10 ≦ | f3 / fw | ≦ 200

  Conditional expression (3) defines the absolute value of the ratio between the focal length of the entire lens system in the in-focus state of the object at infinity at the wide-angle end and the focal length of the third lens group. By satisfying the conditional expression (3), it is possible to properly set the range of the refractive power of the third lens group, and satisfactorily correct spherical aberration, field curvature, and axial chromatic aberration.

  If the lower limit of conditional expression (3) is not reached, the focal length of the third lens group becomes too short, and spherical aberration and field curvature are overcorrected, making it difficult to obtain good optical performance. On the other hand, when the upper limit of conditional expression (3) is exceeded, the focal length of the third lens group becomes too long, and correction of spherical aberration, field curvature, and axial chromatic aberration becomes insufficient, and good optical performance is obtained. Becomes difficult. In addition, since the focal length of the third lens group becomes too long, the total length of the lens system is extended, which makes it difficult to downsize the lens system.

In addition, if the conditional expression (3) satisfies the following range, a more preferable effect can be expected.
(3a) 20 ≦ | f3 / fw | ≦ 170

Further, if the conditional expression (3a) satisfies the following range, a further preferable effect can be expected.
(3b) 50 ≦ | f3 / fw | ≦ 100

Further, in the zoom lens according to the present invention, when the combined focal length of the second lens unit and the third lens unit in the in-focus state of the object at infinity at the wide-angle end is f23w and the focal length of the first lens unit is f1, It is preferable to satisfy the following conditional expression.
(4) 1.1 ≦ | f23w / f1 | ≦ 2.1

  Conditional expression (4) defines the absolute value of the ratio between the focal length of the first lens unit and the combined focal length of the second lens unit and the third lens unit in the in-focus state of the object at infinity at the wide-angle end. Is. By satisfying conditional expression (4), the composite focal length of the second lens unit and the third lens unit in the in-focus state of the object at infinity at the wide-angle end is appropriately set, and the spherical surface generated by the first lens unit Aberration, astigmatism, and axial chromatic aberration can be properly corrected by the second lens group and the third lens group.

  If the lower limit of conditional expression (4) is not reached, the combined focal length of the second lens unit and the third lens unit in the in-focus state of the object at infinity at the wide-angle end becomes too short, resulting in spherical aberration, astigmatism, and axial aberration. Since the upper chromatic aberration is excessively corrected, it becomes difficult to perform appropriate aberration correction. On the other hand, when the upper limit of conditional expression (4) is exceeded, the combined focal length of the second lens unit and the third lens unit in the in-focus state of the object at infinity at the wide-angle end becomes too long, resulting in spherical aberration and astigmatism. However, it is difficult to obtain good optical performance because the correction of axial chromatic aberration is insufficient. In addition, since the combined focal length of the second lens group and the third lens group in the in-focus state of the object at infinity at the wide-angle end becomes long, the total length of the lens system is extended, and it becomes difficult to downsize the lens system.

In addition, if the conditional expression (4) satisfies the following range, a more preferable effect can be expected.
(4a) 1.2 ≦ | f23w / f1 | ≦ 1.8

Further, if the conditional expression (4a) satisfies the following range, a further preferable effect can be expected.
(4b) 1.3 ≦ | f23w / f1 | ≦ 1.6

Furthermore, in the zoom lens according to the present invention, the Abbe number of at least one positive lens included in the third lens group with respect to the d-line (587.56 nm) is νd3P, and at least one lens included in the third lens group When the Abbe number for the d line of the negative lens is νd3n, it is preferable that the following conditional expression is satisfied.
(5) 5.0 ≦ | νd3P−νd3n |

  Conditional expression (5) is defined by the Abbe number for the d-line of at least one positive lens included in the third lens group and the Abbe number for the d-line of at least one negative lens included in the third lens group. It defines the absolute value of the difference. By satisfying the conditional expression (3), in the third lens group, axial chromatic aberration that is generated not only in the visible light region but also in the near-infrared region over the entire zoom range, It is possible to excellently correct lateral chromatic aberration.

  If the lower limit of conditional expression (5) is not reached, correction of axial chromatic aberration and lateral chromatic aberration will be insufficient, and it will be difficult to obtain good optical performance.

  The reason why the upper limit is not set in the conditional expression (5) is that if a lens is made of a general glass material, it is extremely unlikely that an inconvenience will occur due to the upper limit value of the conditional expression (5) becoming too large. is there. However, when a special glass material is selected to form a positive lens and a negative lens arranged in the third lens group, the difference in Abbe number between the positive lens and the negative lens included in the third lens group with respect to the d-line is It may be too large, that is, the value of the conditional expression (5) may become extremely large. In this case, it is feared that the axial chromatic aberration and the lateral chromatic aberration with respect to light in a wide wavelength range are excessively corrected, and it becomes difficult to obtain good optical performance.

Therefore, if the conditional expression (5) satisfies the following range, a more preferable effect can be expected.
(5a) 10.0 ≦ | νd3P−νd3n | ≦ 50.0

Further, if the conditional expression (5a) satisfies the following range, a further preferable effect can be expected.
(5b) 12.0 ≦ | νd3P−νd3n | ≦ 20.0

  Further, in the zoom lens according to the present invention, when the third lens group is composed of a cemented lens composed of a positive lens and a negative lens arranged in order from the object side, the axial chromatic aberration can be effectively reduced with a small number of lenses. The chromatic aberration of magnification can be corrected. Further, by making the cemented surface of the cemented lens convex toward the image side, it is possible to effectively suppress the occurrence of ghost.

  It is preferable that the third lens group is configured by using a cemented lens in order to downsize the lens system. However, even if the third lens group is made up of three or four lenses having an air layer between them, it is assumed that the third lens group has good optical performance on the assumption that it includes one positive lens and one negative lens. Is obtained. Furthermore, by forming an aspherical surface on at least one surface of the lenses that form the third lens group, it becomes possible to more effectively correct spherical aberration and field curvature in a bright lens system.

  By configuring the third lens group as described above, various aberrations generated in the first lens group and the second lens group can be favorably corrected by the third lens group, and good performance can be obtained.

Further, in the zoom lens according to the present invention, the lens aperture of the second lens group can be reduced by disposing the positive lens on the most object side of the second lens group. In addition, when the average value of the Abbe numbers of all the positive lenses included in the second lens group with respect to the d-line is νd2P_ave, it is preferable that the following conditional expression is satisfied.
(6) 65.0 ≦ νd2P_ave

  Conditional expression (6) defines the average value of the Abbe numbers for the d-lines of all the positive lenses included in the second lens group. By satisfying the conditional expression (6), it is possible to satisfactorily correct the axial chromatic aberration and the chromatic aberration of magnification in the second lens group over the entire variable power range with respect to the light of the wavelength from the visible light region to the near infrared region. it can.

  When the lower limit of conditional expression (6) is not reached, the dispersion of the positive lens in the second lens group becomes too large, and the axial chromatic aberration and the magnification with respect to light in the wavelength range from the visible light region to the near infrared region in all variable power regions. The occurrence of chromatic aberration becomes remarkable, and it becomes difficult to obtain good optical performance.

  The reason why the upper limit is not set in the conditional expression (6) is that if a lens is made of a general glass material, it is extremely unlikely that an inconvenience will occur due to the upper limit value of the conditional expression (6) becoming too large. is there. However, when a special glass material is selected to form the positive lens to be arranged in the second lens group, the average value of the Abbe numbers for all d-lines of the positive lenses included in the second lens group becomes too large. That is, the value of conditional expression (6) may become extremely large. In this case, it is feared that the axial chromatic aberration and the lateral chromatic aberration with respect to light in a wide wavelength range are excessively corrected, and it becomes difficult to obtain good optical performance.

Therefore, if the conditional expression (6) satisfies the following range, a more preferable effect can be expected.
(6a) 65.0 ≦ νd2P_ave ≦ 100.0

Further, if the conditional expression (6a) satisfies the following range, a further preferable effect can be expected.
(6b) 70.0 ≦ νd2P_ave ≦ 85.0

  In the zoom lens according to the present invention, by forming an aspherical surface on at least one surface of the positive lens arranged closest to the object in the second lens group, spherical aberration, coma aberration, and field curvature can be improved. Can be corrected. Further, by providing at least one cemented lens in the second lens group, the effect of correcting axial chromatic aberration and lateral chromatic aberration is further improved. Furthermore, if the second lens group is configured to include at least three positive lenses and at least one negative lens, it is possible to more appropriately correct various aberrations and achieve high resolution.

  By the way, in a lens system, chromatic aberration is most concerned in order to maintain the optical performance with respect to light in a long wavelength region. Chromatic aberration is an aberration that occurs as a color shift due to dispersion of the lens glass material. In order to perform good chromatic aberration correction for light in the long wavelength region, the partial dispersion ratio for light in the long wavelength region is appropriate. Must be set to.

  The partial dispersion ratio is a value obtained by dividing the partial dispersion by the main dispersion. The main dispersion means a difference in refractive index between two reference wavelengths, and the partial dispersion means a difference in refractive index between other two wavelengths.

  Here, each spectrum line and its wavelength are set to t line (1013.98 nm), C line (656.27 nm), d line (587.56 nm), F line (486.13 nm), and g line (435.84 nm). , When the arbitrary characters x and y are associated with the respective spectral lines, the respective refractive indices for the x-ray and the y-ray are defined as nx and ny. For example, the refractive index for the d line is represented by nd, and the refractive index for the F line is represented as nF. Further, when the partial dispersion ratio for the x-ray and the y-ray is Pxy, it is defined as Pxy = (nx-ny) / (nF-nC). For example, the partial dispersion ratio PCt for the C line and the t line is expressed as PCt = (nC-nt) / (nF-nC).

  Further, in order to improve the correction of chromatic aberration with respect to light in the long wavelength region, it is preferable to appropriately set the anomalous dispersion of the negative lens included in each lens group with respect to light in the long wavelength region. In a general optical element, when a graph is created with the Abbe number on the horizontal axis and the partial dispersion ratio on the vertical axis, it has the property of riding on a certain straight line, but the one not riding on the straight line is called anomalous dispersion.

  Here, the anomalous dispersion for the C line and the t line will be described. FIG. 1 is a graph for explaining the anomalous dispersion of C line and t line. As shown in FIG. 1, first, on the XY coordinate plane, the Abbe number νd for the d line is taken as the X axis, and the partial dispersion ratio PCt for the C line and the t line is taken as the Y axis. Then, two points on the coordinate plane are defined with respect to the two reference glass materials regarding the C line and the t line, and a straight line connecting the two points is defined as a “standard line Ct regarding the C line and the t line”. In the present invention, the standard line Ct is defined as “a standard line Ct: Pct = 0.546 + 0.00467 × νd” as a straight line having a slope of 0.00467 and an intercept of 0.546. Thereby, the anomalous dispersion of the C line and the t line can be defined as the value of the anomalous dispersion of the deviation ΔPCt of the PCt from the standard line Ct with respect to (νd, PCt) of the given glass material. For example, assuming that the Abbe number for d line of any glass material i is νd_i and the partial dispersion ratio PCt_i for C line and t line, the anomalous dispersion ΔPCt_i for C line and t line of any glass material i is ΔPCt_i = PCt_i- It can be calculated as (0.546 + 0.0047 × νd_i). ΔPCt_i defined in this way represents the anomalous dispersion of the C line and the t line.

  In the case of a lens system considering even the correction of chromatic aberration in the near infrared region, it is desirable to use a glass material of ΔPCt = PCt− (0.546 + 0.00467 × νd) ≧ 0 for the anomalous dispersion of the negative lens used in each lens group. .. A glass material with ΔPCt ≧ 0 tends to have a small dispersion (nC-nt) from the C line to the t line on the low dispersion side where νd is relatively large. Therefore, the chromatic aberration from the C line to the t line generated in the negative lens It is possible to correct chromatic aberration for light with a wide wavelength range from the visible light region to the near infrared region by providing a positive lens that is arranged to correct chromatic aberration with appropriate anomalous dispersion. is there.

Therefore, in the zoom lens according to the present invention, assuming that the second lens group includes at least one negative lens, the C line and t line of at least one negative lens included in the second lens group are included. It is preferable that the following conditional expression is satisfied, where PCt_2n_i is the partial dispersion ratio and the Abbe number for the d line of the negative lens for which the value of PCt_2n_i is calculated is νd_2n_i.
(7) 0.000 ≦ PCt_2n_i− (0.546 + 0.00467 × νd_2n_i)

  Conditional expression (7) defines the anomalous dispersion of the negative lens included in the second lens group with respect to the C line and the t line. By satisfying the conditional expression (7), it is possible to excellently correct axial chromatic aberration and lateral chromatic aberration with respect to light in a wavelength range including the near infrared range from the C line to the t line in the second lens group. When the second lens group includes a plurality of negative lenses, any one of the negative lenses is selected, and the calculated values of PCt_2n_i and νd_2n_i satisfy the conditional expression (7). If you are satisfied.

  If the lower limit of conditional expression (7) is not reached, the anomalous dispersion of the negative lens element included in the second lens group becomes too small, and the axial chromatic aberration and the chromatic aberration of magnification with respect to the light in the wavelength range including the t-line are significantly generated. Therefore, it becomes difficult to obtain good optical performance for light in the wavelength range including the near infrared range.

  The reason why the upper limit is not set in the conditional expression (7) is that if the lens is made of a general glass material, there is very little possibility of causing a problem due to the upper limit value of the conditional expression (7) becoming too large. is there. However, when a special glass material is selected to form the negative lens included in the second lens group, the anomalous dispersion of the negative lens becomes too large, that is, the value of conditional expression (7) becomes extremely large. It can happen. In this case, it is feared that the correction of the chromatic aberration corresponding to the light in the wavelength range including the t-line becomes excessive, and it becomes difficult to obtain good optical performance for the light in the wavelength range including the near infrared range.

Therefore, if the conditional expression (7) satisfies the following range, a more preferable effect can be expected.
(7a) 0.001 ≦ PCt_2n_i− (0.546 + 0.00467 × νd_2n_i) ≦ 0.05

Further, if the conditional expression (7a) satisfies the following range, a further preferable effect can be expected.
(7b) 0.0015 ≦ PCt_2n_i− (0.546 + 0.00467 × νd_2n_i) ≦ 0.04

Further, if the conditional expression (7b) satisfies the following range, a further preferable effect can be expected.
(7c) 0.002 ≦ PCt_2n_i− (0.546 + 0.00467 × νd_2n_i) ≦ 0.03

Furthermore, in the zoom lens according to the present invention, at least the first lens group includes at least one positive lens and at least two negative lenses. The Abbe number of one positive lens with respect to the d line is νd1p, the partial dispersion ratio of at least one negative lens included in the first lens group with respect to the C line and the t line is PCt_1n_i, and the value of the PCt_1n_i is negative. When the Abbe number of the lens with respect to the d-line is νd_1n_i, it is preferable that the following conditional expression is satisfied.
(8) νd1p ≦ 40.0
(9) 0.000≤PCt_1n_i- (0.546 + 0.00467 × νd_1n_i)

  Conditional expression (8) defines the Abbe number for the d-line of at least one positive lens included in the first lens group. By satisfying the conditional expression (8), it is possible to excellently correct axial chromatic aberration and lateral chromatic aberration mainly with respect to light having a wavelength in the visible light region. When the first lens group includes a plurality of positive lenses, any one of them should satisfy the conditional expression (8).

  If the lower limit of conditional expression (8) is not reached, axial chromatic aberration and chromatic aberration of magnification with respect to light having a wavelength in the visible light range will be noticeable, and it will be difficult to suppress chromatic aberration that occurs during zooming in particular. It becomes difficult to obtain optical performance.

  The reason why the lower limit is not set in the conditional expression (8) is that if a lens is formed of a general glass material, it is extremely unlikely that an inconvenience will occur due to the lower limit value of the conditional expression (8) becoming too small. is there. However, when a special glass material is selected to form the positive lens included in the first lens group, the Abbe number of the positive lens with respect to the d-line becomes too small, that is, the value of the conditional expression (8) is extremely small. It can happen. In this case, it is feared that the axial chromatic aberration and the lateral chromatic aberration with respect to light having a wavelength in the visible light region are excessively corrected, and it becomes difficult to obtain good optical performance.

Therefore, if the conditional expression (8) satisfies the following range, a more preferable effect can be expected.
(8a) 10.0 ≦ νd1p ≦ 38.0

Further, if the conditional expression (8a) satisfies the following range, a further preferable effect can be expected.
(8b) 17.0 ≦ νd1p ≦ 36.0

  Conditional expression (9) defines the anomalous dispersion of the negative lens included in the first lens group with respect to the C line and the t line. By satisfying conditional expression (9), it is possible to excellently correct axial chromatic aberration and lateral chromatic aberration of light in the wavelength range including the near infrared range from the C line to the t line in the first lens group. Since the first lens group includes at least two negative lenses, any one of the negative lenses is selected, and the calculated values of PCt_1n_i and νd_1n_i satisfy the conditional expression (9). If you are satisfied.

  If the lower limit of conditional expression (9) is exceeded, the anomalous dispersion of the negative lens included in the first lens group with respect to the C-line and the t-line becomes too small, and axial chromatic aberration for light in the wavelength range including the t-line, Since chromatic aberration of magnification occurs remarkably, it becomes difficult to obtain good optical performance for light in a wavelength range including the near infrared range.

  The reason why the upper limit is not set in the conditional expression (9) is that if the lens is made of a general glass material, it is extremely unlikely that an inconvenience will occur due to the upper limit value of the conditional expression (9) becoming too large. is there. However, when a special glass material is selected to form the negative lens included in the first lens group, the anomalous dispersion of the negative lens becomes too large, that is, the value of the conditional expression (9) becomes extremely large. It can happen. In this case, it is feared that the correction of the chromatic aberration with respect to the light in the wavelength range including the t-line becomes excessive, and it becomes difficult to obtain good optical performance with respect to the light in the wavelength range including the near-infrared range.

Therefore, if the conditional expression (9) satisfies the following range, a more preferable effect can be expected.
(9a) 0.001 ≦ PCt_1n_i− (0.546 + 0.00467 × νd_1n_i) ≦ 0.05

Further, if the conditional expression (9a) satisfies the following range, a further preferable effect can be expected.
(9b) 0.0015 ≦ PCt_1n_i− (0.546 + 0.00467 × νd_1n_i) ≦ 0.04

Further, if the conditional expression (9b) satisfies the following range, a further preferable effect can be expected.
(9c) 0.002 ≦ PCt_1n_i− (0.546 + 0.00467 × νd_1n_i) ≦ 0.03

  In the zoom lens according to the present invention, if the first lens group includes at least one positive lens and two negative lenses, the above-described effect can be sufficiently obtained, but three or more negative lenses are provided. By providing the lens, a better chromatic aberration correction effect can be obtained.

Further, in the zoom lens according to the present invention, the partial dispersion ratio of at least one negative lens included in the third lens group with respect to the C line and the t line is PCt_3n_i, and the value of the PCt_3n_i is calculated as the d line of the negative lens. It is preferable that the following conditional expression is satisfied, where the Abbe number with respect to is νd — 3n_i.
(10) 0.000 ≦ PCt — 3n_i− (0.546 + 0.00467 × νd — 3n_i)

  Conditional expression (10) defines the anomalous dispersion of the negative lens included in the third lens group with respect to the C line and the t line. By satisfying conditional expression (10), it is possible to excellently correct axial chromatic aberration and lateral chromatic aberration with respect to light in a wavelength range including the near infrared range from the C line to the t line in the third lens group. When the third lens group includes a plurality of negative lenses, any one of the negative lenses is selected, and the calculated values of PCt_3n_i and νd_3n_i satisfy the conditional expression (10). If you are satisfied.

  If the lower limit of conditional expression (10) is not reached, the anomalous dispersion of the negative lens included in the third lens group with respect to the C-line and the t-line becomes too small, and axial chromatic aberration for light in the wavelength range including the t-line is reduced. However, the occurrence of lateral chromatic aberration becomes remarkable, and it becomes difficult to obtain good optical performance for light in the wavelength range including the near infrared range.

  The reason why the upper limit is not set in the conditional expression (10) is that if a lens is made of a general glass material, it is extremely unlikely that an inconvenience will occur due to the upper limit value of the conditional expression (10) becoming too large. is there. However, when a special glass material is selected to form the negative lens included in the third lens group, the anomalous dispersion of the negative lens becomes too large, that is, the value of conditional expression (10) becomes extremely large. It can happen. In this case, it is feared that the correction of the chromatic aberration with respect to the light in the wavelength range including the t-line becomes excessive, and it becomes difficult to obtain good optical performance with respect to the light in the wavelength range including the near infrared range.

Therefore, if the conditional expression (10) satisfies the following range, a more preferable effect can be expected.
(10a) 0.001 ≦ PCt — 3n_i− (0.546 + 0.00467 × νd — 3n_i) ≦ 0.05

Further, if the conditional expression (10a) satisfies the following range, a further preferable effect can be expected.
(10b) 0.0015 ≦ PCt — 3n_i− (0.546 + 0.00467 × νd — 3n_i) ≦ 0.04

Further, if the conditional expression (10b) satisfies the following range, a further preferable effect can be expected.
(10c) 0.002 ≦ PCt — 3n_i− (0.546 + 0.00467 × νd — 3n_i) ≦ 0.03

Further, in the zoom lens according to the present invention, when the focal length of the first lens group is f1 and the focal length of the second lens group is f2, it is preferable that the following conditional expression is satisfied.
(11) 0.4 ≦ | f1 / f2 | ≦ 1.1

  Conditional expression (11) defines the absolute value of the ratio between the focal length of the first lens group and the focal length of the second lens group. By satisfying conditional expression (11), a bright lens system can be obtained, and the amount of movement of the first lens group due to zooming can be appropriately set, and astigmatism and field curvature associated with zooming can be achieved. Can be suppressed.

  If the lower limit of conditional expression (11) is not reached, the focal length of the first lens group becomes too short, the field curvature is overcorrected, and it becomes difficult to correct astigmatism and distortion. .. In particular, in a bright lens system, it becomes extremely difficult to correct various aberrations including spherical aberration, field curvature, and astigmatism during zooming, and it is difficult to realize a bright lens system having good optical performance. On the other hand, if the upper limit of conditional expression (11) is exceeded, the focal length of the first lens group becomes too long, and the amount of movement of the first lens group increases during zooming from the wide-angle end to the telephoto end. It becomes difficult to improve the optical performance while maintaining the miniaturization of the entire lens system.

It should be noted that, if the conditional expression (11) satisfies the following range, a more preferable effect can be expected.
(11a) 0.5 ≦ | f1 / f2 | ≦ 0.9

Further, if the conditional expression (11a) satisfies the following range, a further preferable effect can be expected.
(11b) 0.6 ≦ | f1 / f2 | ≦ 0.8

Further, in the zoom lens according to the present invention, when the moving amount of the second lens unit is X2 and the focal length of the second lens unit is f2 during zooming from the wide-angle end to the telephoto end, the following conditional expression is satisfied. Preferably.
(12) 0.2 ≦ | X2 / f2 | ≦ 0.9

  Conditional expression (12) defines the ratio between the movement amount of the second lens unit and the focal length of the second lens unit during zooming from the wide-angle end to the telephoto end. By satisfying the conditional expression (12), the amount of movement of the second lens unit and the refractive power of the second lens unit at the time of zooming can be appropriately set, and spherical aberration and field curvature fluctuations at the time of zooming can be suppressed. It can be corrected appropriately.

  If the lower limit of conditional expression (12) is not reached, the amount of movement of the second lens group during zooming becomes too small, and spherical aberration and field curvature during zooming become excessively corrected, resulting in good optical performance. Will be difficult to obtain. On the other hand, when the upper limit of conditional expression (12) is exceeded, the amount of movement of the second lens unit during zooming increases too much, correction of spherical aberration and field curvature is insufficient, and the overall length of the lens system increases. I will end up.

In addition, if the conditional expression (12) satisfies the following range, a more preferable effect can be expected.
(12a) 0.3 ≦ | X2 / f2 | ≦ 0.8

Further, if the conditional expression (12a) satisfies the following range, a further preferable effect can be expected.
(12b) 0.4 ≦ | X2 / f2 | ≦ 0.7

Further, in the zoom lens according to the present invention, the combined focal length of the second lens group and the third lens group in the infinity object focused state at the telephoto end is f23t, and the entire lens system in the infinity object focused state at the telephoto end is f23t. When the focal length of is ft, it is preferable to satisfy the following conditional expression.
(13) 1.1 ≦ f23t / ft ≦ 2.8

  Conditional expression (13) is the focal length of the entire lens system in the in-focus state of the object at infinity at the telephoto end, and the combined focal length of the second lens group and the third lens group in the state of the in-focus object at the telephoto end. It defines the ratio of. By satisfying conditional expression (13), the combined focal length of the second lens unit and the third lens unit in the in-focus state of the object at infinity at the telephoto end is appropriately set, and spherical aberration at the telephoto end of the lens system is set. It is possible to properly correct coma and field curvature.

  If the lower limit of conditional expression (13) is not reached, the combined focal length of the second lens unit and the third lens unit in the in-focus state of the object at infinity at the telephoto end becomes too short, resulting in spherical aberration at the telephoto end of the lens system. However, since the coma aberration and the curvature of field are excessively corrected, it becomes difficult to appropriately correct the aberration. On the other hand, when the upper limit of conditional expression (13) is exceeded, the combined focal length of the second lens unit and the third lens unit in the in-focus state of the object at infinity at the telephoto end becomes too long, and at the telephoto end of the lens system. Correction of spherical aberration, coma, and field curvature is insufficient, and it becomes difficult to obtain good optical performance.

In addition, if the conditional expression (13) satisfies the following range, a more preferable effect can be expected.
(13a) 1.2 ≦ f23t / ft ≦ 2.2

Further, if the conditional expression (13a) satisfies the following range, a further preferable effect can be expected.
(13b) 1.3 ≦ f23t / ft ≦ 1.8

Furthermore, in the zoom lens according to the present invention, when the focal length of the second lens group is f2 and the focal length of the third lens group is f3, it is preferable that the following conditional expressions be satisfied.
(14) 3.2 ≦ | f3 / f2 | ≦ 80.0

  Conditional expression (14) defines the absolute value of the ratio between the focal length of the second lens group and the focal length of the third lens group. By satisfying the conditional expression (14), it is possible to effectively suppress the astigmatism and the field curvature that are generated due to the movement of the second lens group during zooming.

  If the lower limit of conditional expression (14) is not reached, the focal length of the second lens unit becomes too long, making it difficult to correct field curvature. Particularly, when zooming from the wide-angle end to the telephoto end, it is preferable. It becomes difficult to obtain optical performance. On the other hand, when the upper limit of conditional expression (14) is exceeded, the focal length of the second lens group becomes too short, the field curvature is overcorrected, and it becomes difficult to satisfactorily correct astigmatism. Become. Particularly in a bright lens system, it becomes extremely difficult to correct various aberrations including spherical aberration, field curvature, and astigmatism during zooming, and it becomes difficult to realize a lens system having good optical performance.

In addition, if the conditional expression (14) satisfies the following range, a more preferable effect can be expected.
(14a) 4.0 ≦ | f3 / f2 | ≦ 70.0

Further, if the conditional expression (14a) satisfies the following range, a further preferable effect can be expected.
(14b) 7.5 ≦ | f3 / f2 | ≦ 37.0

  As described above, according to the present invention, by providing the above-described configuration, it has a high optical performance capable of supporting a solid-state imaging device with a large aperture ratio, high pixel count, and high sensitivity, while having a simple configuration. And to realize a small zoom lens that can satisfactorily correct various aberrations that occur for light with a wide range of wavelengths from the visible light region to the near infrared region over the entire zoom range. You can

  The zoom lens according to the present invention having such features can be used not only in a camera for photography that mainly uses light in the visible light range, but also in various imaging devices such as a surveillance camera that also performs nighttime shooting. In particular, it has a high optical performance suitable for an image pickup apparatus including a solid-state image pickup element with high pixels and high sensitivity.

  A further object of the present invention is to provide a high-performance image pickup device capable of obtaining a good image regardless of day or night. In order to achieve this object, an image pickup apparatus may be configured to include a zoom lens having the above configuration and a solid-state image pickup element that converts an optical image formed by this zoom lens into an electrical signal. By doing so, it becomes possible to satisfactorily correct various aberrations that occur with respect to light having a wide range of wavelengths from the visible light region to the near-infrared region over the entire zoom range, regardless of day or night. Thus, it is possible to realize a high-performance image pickup device that can obtain a good image.

  Embodiments of a zoom lens according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the examples below.

FIG. 2 is a sectional view taken along the optical axis showing the configuration of the zoom lens according to the first example. This figure shows the in-focus state of an object at infinity at the wide-angle end of the lens system. This zoom lens comprises, in order from the object side (not shown), a first lens group G ₁₁ having a negative refractive power, a second lens group G ₁₂ having a positive refractive power, and a third lens group having a positive refractive power. G ₁₃ and are arranged. An aperture stop STP that defines a predetermined aperture is arranged between the first lens group G ₁₁ and the second lens group G ₁₂ . A cover glass CG is arranged between the third lens group G ₁₃ and the image plane IMG.

The first lens group G ₁₁ is configured by arranging a negative lens L ₁₁₁ , a negative lens L ₁₁₂ , a negative lens L _113, and a positive lens L _{114 in} order from the object side. An aspherical surface is formed on the object side surface of the negative lens L ₁₁₃ . The negative lens L ₁₁₃ and the positive lens L ₁₁₄ are cemented together.

The second lens group G ₁₂ is configured by arranging a positive lens L ₁₂₁ , a negative lens L ₁₂₂ , a positive lens L ₁₂₃ , a negative lens L _124, and a positive lens L _{125 in} order from the object side. .. Aspherical surfaces are formed on both surfaces of the positive lens L ₁₂₁ . The negative lens L ₁₂₂ and the positive lens L ₁₂₃ are cemented together. The negative lens L ₁₂₄ and the positive lens L ₁₂₅ are cemented together.

The third lens group G ₁₃ is configured by arranging a positive lens L ₁₃₁ and a negative lens L _{132 in this} order from the object side. An aspherical surface is formed on the object side surface of the positive lens L ₁₃₁ . The positive lens L ₁₃₁ and the negative lens L ₁₃₂ are cemented together. The cemented surface between the positive lens L ₁₃₁ and the negative lens L ₁₃₂ has a convex shape on the image plane IMG side.

In this zoom lens, the first lens group G ₁₁ forms a small convex locus along the optical axis on the image plane IMG side while the aperture stop STP and the third lens group G ₁₃ are fixed with respect to the image plane IMG. And the second lens group G ₁₂ is moved along the optical axis from the image plane IMG side to the object side to perform zooming from the wide-angle end to the telephoto end (see the solid line arrow in FIG. 2). reference). Further, the first lens group G ₁₁ is moved along the optical axis so as to form a small convex locus on the image plane IMG side, and focusing from the infinity object focus state to the closest object focus state is performed. Do (see the dashed arrow in FIG. 2).

  Hereinafter, various numerical data regarding the zoom lens according to the example 1 will be shown.

(Surface data)
r ₁ = 28.560
d ₁ = 0.70 nd ₁ = 1.65844 νd ₁ = 50.86 PCt ₁ = 0.7742
r ₂ = 6.875
d ₂ = 2.74
r ₃ = 19.908
d ₃ = 0.50 nd ₂ = 1.56883 νd ₂ = 56.04 PCt ₂ = 0.8080
r ₄ = 9.323
d ₄ = 3.73
r ₅ = -10.508 (aspherical surface)
_{d 5 = 0.60 nd 3 = 1.62263} νd 3 = 58.16 PCt 3 = 0.8464
r ₆ = 13.006
_{d 6 = 1.89 nd 4 = 1.91082} νd 4 = 35.25 PCt 4 = 0.7131
r ₇ = -44.951
d ₇ = D (7) (variable)
r ₈ = ∞ (aperture stop)
d ₈ = D (8) (variable)
r ₉ = 10.758 (aspherical surface)
d ₉ = 3.59 nd ₅ = 1.55332 νd ₅ = 71.68 PCt ₅ = 0.8164
r ₁₀ = -16.500 (aspherical surface)
d ₁₀ = 0.15
r ₁₁ = 228.575
d ₁₁ = 0.50 nd ₆ = 1.51680 νd ₆ = 64.20 PCt ₆ = 0.8682
r ₁₂ = 9.700
_{d 12 = 4.22 nd 7 = 1.49700} νd 7 = 81.65 PCt 7 = 0.8305
r ₁₃ = -10.326
d ₁₃ = 0.15
r ₁₄ = -195.147
_{d 14 = 0.50 nd 8 = 1.80610} νd 8 = 40.73 PCt 8 = 0.7464
r ₁₅ = 7.112
_{d 15 = 3.49 nd 9 = 1.49700} νd 9 = 81.65 PCt 9 = 0.8305
r ₁₆ = -16.606
d ₁₆ = D (16) (variable)
r ₁₇ = -22.555 (aspherical surface)
_{d 17 = 2.26 nd 10 = 1.82080} νd 10 = 42.71 PCt 10 = 0.7536
r ₁₈ = -9.150
d ₁₈ = 0.50 nd ₁₁ = 1.72825 νd ₁₁ = 28.32 PCt ₁₁ = 0.6855
r ₁₉ = -26.098
d ₁₉ = 5.49
r ₂₀ = ∞
d ₂₀ = 0.50 nd ₁₂ = 1.51680 νd ₁₂ = 64.20 PCt ₁₂ = 0.8682
r ₂₁ = ∞
d ₂₁ = BF
r ₂₂ = ∞ (image plane)

Cone coefficient (k) and aspherical coefficient (A, B, C, D, E)
(5th surface)
k = 0,
A = 0, B = 1.009677 × 10 ^-6 , C = -4.85235 × 10 ^-6 ,
D = 1.74189 × 10 ^-7 , E = -4.16360 × 10 ^-9
(9th surface)
k = 0,
A = 0, B = -1.916 13 × 10 ^-4 , C = 3.26425 × 10 ^-6 ,
D = 3.00419 x 10 ^-8 , E = -2.56440 x 10 ^-9
(10th surface)
k = 0,
A = 0, B = 4.25683 × 10 ^-4 , C = 1.004005 × 10 ^-6 ,
D = 1.78047 × 10 ^-7 , E = -4.32383 × 10 ^-9
(17th surface)
k = 0,
A = 0, B = -3.89074 × 10 ^-5 , C = 7.70391 × 10 ^-7 ,
D = 0, E = 0

(Various data)
Magnification ratio: 1.88
Wide-angle end Intermediate focal position Telephoto end focal length (at infinity object focused state) 4.42 5.82 8.34
F number 1.55 1.78 2.43
Half angle of view (ω) 66.99 47.79 32.55
Image height 4.75 4.75 4.75
Lens system total length 46.58 44.00 43.18
Back focus (BF) 2.00 2.00 2.00
D (7) 5.68 3.08 2.26
D (8) 6.16 4.28 0.85
D (16) 1.23 3.11 6.55

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 -7.61 3.42
2 9 10.56 -5.31
3 17 28 1.39 0.00

(Numerical value regarding conditional expression (1))
| F1 / fw | = 1.72

(Numerical value regarding conditional expression (2))
f23w (composite focal length of the second lens group G ₁₂ and the third lens group G _{13 in the in-} focus state of an object at infinity at the wide-angle end) = 11.06
f23w / fw = 2.50

(Numerical value regarding conditional expression (3))
| F3 / fw | = 63.48

(Numerical value regarding conditional expression (4))
| F23w / f1 | = 1.45

(Numerical value regarding conditional expression (5))
│νd3P-νd3n | = 14.4

(Numerical value regarding conditional expression (6))
νd2P_ave = 78.3

(Numerical value regarding conditional expression (7))
PCt_2n_i- (0.546 + 0.00467 × νd_2n_i) = 0.0224

(Numerical value regarding conditional expression (8))
νd1p = 35.3

(Numerical value regarding conditional expression (9))
PCt_1n_i- (0.546 + 0.00467 × νd_1n_i) = 0.0288

(Numerical value regarding conditional expression (10))
PCt_3n_i- (0.546 + 0.00467 × νd_3n_i) = 0.0072

(Numerical value regarding conditional expression (11))
| F1 / f2 | = 0.72

(Numerical value regarding conditional expression (12))
| X2 / f2 | = 0.50

(Numerical value regarding conditional expression (13))
f23t (composite focal length of the second lens group G ₁₂ and the third lens group G _{13 in the in-} focus state of an object at infinity at the telephoto end) = 11.28
f23t / ft = 1.35

(Numerical value regarding conditional expression (14))
| F3 / f2 | = 26.66

  FIG. 3 is a diagram of various types of aberration of the zoom lens according to the first example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the g line (435.84 nm), and the long broken line is the IR line (850. The characteristic of the wavelength corresponding to (00 nm) is shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

FIG. 4 is a sectional view taken along the optical axis, showing the configuration of the zoom lens according to the second example. This figure shows the in-focus state of an object at infinity at the wide-angle end of the lens system. This zoom lens comprises, in order from the object side, not shown, a first lens group G ₂₁ having a negative refractive power, a second lens group G ₂₂ having a positive refractive power, and a third lens group having a positive refractive power. G ₂₃ and are arranged. An aperture stop STP that defines a predetermined aperture is arranged between the first lens group G ₂₁ and the second lens group G ₂₂ . A cover glass CG is arranged between the third lens group G ₂₃ and the image plane IMG.

The first lens group G ₂₁ includes a negative lens L ₂₁₁ , a negative lens L _212, and a positive lens L ₂₁₃ , which are arranged in this order from the object side. Aspherical surfaces are formed on both surfaces of the negative lens L ₂₁₁ and on the image surface IMG side surface of the positive lens L ₂₁₃ . The negative lens L ₂₁₂ and the positive lens L ₂₁₃ are cemented together.

The second lens group G ₂₂ is configured by arranging a positive lens L ₂₂₁ , a negative lens L ₂₂₂ , a positive lens L ₂₂₃ , a negative lens L _224, and a positive lens L _{225 in this} order from the object side. .. Aspherical surfaces are formed on both surfaces of the positive lens L ₂₂₁ . The negative lens L ₂₂₂ and the positive lens L ₂₂₃ are cemented together. The negative lens L ₂₂₄ and the positive lens L ₂₂₅ are cemented together.

The third lens group G ₂₃ is configured by arranging a positive lens L ₂₃₁ and a negative lens L _{232 in} order from the object side. The positive lens L ₂₃₁ and the negative lens L ₂₃₂ are cemented together. The cemented surface between the positive lens L ₂₃₁ and the negative lens L ₂₃₂ has a convex shape on the image plane IMG side.

In this zoom lens, the first lens group G ₂₁ forms a small convex locus along the optical axis on the image plane IMG side while the aperture stop STP and the third lens group G ₂₃ are fixed with respect to the image plane IMG. And the second lens group G ₂₂ is moved along the optical axis from the image plane IMG side to the object side to perform zooming from the wide-angle end to the telephoto end (see the solid arrow in FIG. 4). reference). Further, the first lens group G ₂₁ is moved along the optical axis so as to form a small convex locus on the image plane IMG side to perform focusing from the infinity object focused state to the closest object focused state. Do (see the dashed arrow in FIG. 4).

  Hereinafter, various numerical data regarding the zoom lens according to the second embodiment will be shown.

(Surface data)
r ₁ = 131.432 (aspherical surface)
d ₁ = 0.80 nd ₁ = 1.82080 νd ₁ ＝ 42.71 PCt ₁ ＝ 0.7536
r ₂ = 7.500 (aspherical surface)
d ₂ = 6.41
r ₃ = -7.511
d ₃ = 0.52 nd ₂ = 1.59349 νd ₂ = 67.00 PCt ₂ = 0.8494
r ₄ = 14.710
d ₄ = 1.78 nd ₃ = 1.88202 νd ₃ = 37.22 PCt ₃ = 0.7227
r ₅ = -27.238 (aspherical surface)
d ₅ = D (5) (variable)
r ₆ = ∞ (aperture stop)
d ₆ = D (6) (variable)
r ₇ = 9.752 (aspherical surface)
d ₇ = 4.00 nd ₄ = 1.55332 νd ₄ = 71.68 PCt ₄ = 0.8164
r ₈ = -17.883 (aspherical surface)
d ₈ = 0.53
r ₉ = 55.332
d ₉ = 0.50 nd ₅ = 1.62041 νd ₅ = 60.34 PCt ₅ = 0.8383
r ₁₀ = 7.902
_{d 10 = 3.74 nd 6 = 1.49700} νd 6 = 81.65 PCt 6 = 0.8305
r ₁₁ = -11.975
d ₁₁ = 0.15
r ₁₂ = -226.211
d ₁₂ = 0.50 nd ₇ = 1.80610 νd ₇ ＝ 40.73 PCt ₇ ＝ 0.7464
r ₁₃ = 7.900
_{d 13 = 3.55 nd 8 = 1.49700} νd 8 = 81.65 PCt 8 = 0.8305
r ₁₄ = -15.426
d ₁₄ = D (14) (variable)
r ₁₅ = -54.287
_{d 15 = 2.77 nd 9 = 1.74400} νd 9 = 44.90 PCt 9 = 0.7459
r ₁₆ = -7.290
d ₁₆ = 0.50 nd ₁₀ = 1.69895 νd ₁₀ = 30.05 PCt ₁₀ = 0.6936
r ₁₇ = -81.768
d ₁₇ = 4.80
r ₁₈ = ∞
d ₁₈ = 1.50 nd ₁₁ = 1.51680 νd ₁₁ = 64.20 PCt ₁₁ = 0.8682
r ₁₉ = ∞
d ₁₉ = BF
r ₂₀ = ∞ (image plane)

Cone coefficient (k) and aspherical coefficient (A, B, C, D, E)
(First side)
k = 0,
A = 0, B = 2.13175 × 10 ^-4 , C = -4.85138 × 10 ^-7 ,
D = -1.09051 x 10 ^-8 , E = 1.18921 x 10 ^-10
(Second side)
k = 0,
A = 0, B = 1.17722 × 10 ^-4 , C = 4.20431 × 10 ^-7 ,
D = 2.28582 × 10 ^-7 , E = -4.06642 × 10 ^-9
(5th surface)
k = 0,
A = 0, B = 2.95068 × 10 ^-5 , C = 3.66591 × 10 ^-6 ,
D = -2.18995 × 10 ^-7 , E = 5.67556 × 10 ^-9
(Seventh surface)
k = 0,
A = 0, B = -1.72280 × 10 ^-4 , C = 4.22093 × 10 ^-6 ,
D = -4.83929 x 10 ^-8 , E = 7.48395 x 10 ^-10
(Eighth surface)
k = 0,
A = 0, B = 4.19117 × 10 ^-4 , C = 2.50848 × 10 ^-6 ,
D = 2.80895 x 10 ^-8 , E = 1.14497 x 10 ^-10

(Various data)
Magnification ratio: 1.89
Wide-angle end Intermediate focal position Telephoto end focal length (at infinity object focused state) 4.42 5.83 8.36
F number 1.54 1.79 2.50
Half angle of view (ω) 63.96 47.71 32.79
Image height 4.75 4.75 4.75
Lens system total length 46.39 44.08 43.65
Back focus (BF) 1.00 1.00 1.00
D (5) 4.42 2.11 1.67
D (6) 7.09 5.05 1.35
D (14) 1.83 3.88 7.58

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 -7.27 2.74
2 7 10.81 -5.74
3 15 734.04 0.00

(Numerical value regarding conditional expression (1))
｜ f1 / fw ｜ = 1.64

(Numerical value regarding conditional expression (2))
f23w (composite focal length of the second lens group G ₂₂ and the third lens group G _{23 in the in-} focus state of the object at infinity at the wide-angle end) = 11.06
f23w / fw = 2.50

(Numerical value regarding conditional expression (3))
| F3 / fw | = 165.95

(Numerical value regarding conditional expression (4))
| F23w / f1 | = 1.52

(Numerical value regarding conditional expression (5))
│νd3P-νd3n | = 14.9

(Numerical value regarding conditional expression (6))
νd2P_ave = 78.3

(Numerical value regarding conditional expression (7))
PCt_2n_i- (0.546 + 0.00467 × νd_2n_i) = 0.0105

(Numerical value regarding conditional expression (8))
νd1p = 37.2

(Numerical value regarding conditional expression (9))
PCt_1n_i- (0.546 + 0.00467 × νd_1n_i) = 0.0081

(Numerical value regarding conditional expression (10))
PCt_3n_i- (0.546 + 0.00467 × νd_3n_i) = 0.0073

(Numerical value regarding conditional expression (11))
| F1 / f2 | = 0.67

(Numerical value regarding conditional expression (12))
| X2 / f2 | = 0.53

(Numerical value regarding conditional expression (13))
f23t (composite focal length of the second lens group G ₂₂ and the third lens group G _{23 in the in-} focus state at infinity at the telephoto end) = 11.15
f23t / ft = 1.33

(Numerical value regarding conditional expression (14))
| F3 / f2 | = 67.92

  FIG. 5 is a diagram of various types of aberration of the zoom lens according to the second example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the g line (435.84 nm), and the long broken line is the IR line (850. The characteristic of the wavelength corresponding to (00 nm) is shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

FIG. 6 is a sectional view taken along the optical axis, showing the configuration of the zoom lens according to the third example. This figure shows the in-focus state of an object at infinity at the wide-angle end of the lens system. This zoom lens comprises, in order from the object side (not shown), a first lens group G ₃₁ having a negative refractive power, a second lens group G ₃₂ having a positive refractive power, and a third lens group having a positive refractive power. G ₃₃ and are arranged. An aperture stop STP that defines a predetermined aperture is arranged between the first lens group G ₃₁ and the second lens group G ₃₂ . A cover glass CG is arranged between the third lens group G ₃₃ and the image plane IMG.

The first lens group G ₃₁ is composed of, in order from the object side, a negative lens L ₃₁₁ , a negative lens L ₃₁₂ , a negative lens L _313, and a positive lens L ₃₁₄ . An aspherical surface is formed on the object side surface of the negative lens L ₃₁₃ . The negative lens L ₃₁₃ and the positive lens L ₃₁₄ are cemented together.

The second lens group G ₃₂ is configured such that a positive lens L ₃₂₁ , a negative lens L ₃₂₂ , a positive lens L ₃₂₃ , a negative lens L _324, and a positive lens L ₃₂₅ are arranged in this order from the object side. .. Aspherical surfaces are formed on both surfaces of the positive lens L ₃₂₁ . The negative lens L ₃₂₂ and the positive lens L ₃₂₃ are cemented together. The negative lens L ₃₂₄ and the positive lens L ₃₂₅ are cemented together.

The third lens group G ₃₃ includes a positive lens L ₃₃₁ and a negative lens L ₃₃₂ , which are arranged in this order from the object side. An aspherical surface is formed on the object side surface of the positive lens L ₃₃₁ . The positive lens L ₃₃₁ and the negative lens L ₃₃₂ are cemented together. The cemented surface between the positive lens L ₃₃₁ and the negative lens L ₃₃₂ has a convex shape on the image plane IMG side.

In this zoom lens, the first lens group G ₃₁ forms a convex locus along the optical axis on the image plane IMG side while the aperture stop STP and the third lens group G ₃₃ are fixed with respect to the image plane IMG. And the second lens group G ₃₂ is moved along the optical axis from the image plane IMG side to the object side to perform zooming from the wide-angle end to the telephoto end (see the solid arrow in FIG. 6). ). Further, the first lens group G ₃₁ is moved along the optical axis so as to form a convex locus on the image plane IMG side, and focusing is performed from the infinity object focused state to the closest object focused state. (See dashed arrow in FIG. 6).

  Hereinafter, various numerical data regarding the zoom lens according to the third embodiment will be shown.

(Surface data)
r ₁ = 22.334
d ₁ = 0.70 nd ₁ = 1.88300 νd ₁ ＝ 40.80 PCt ₁ ＝ 0.7381
r ₂ = 6.875
d ₂ = 2.79
r ₃ = 21.150
_{d 3 = 0.50 nd 2 = 1.48749} νd 2 = 70.45 PCt 2 = 0.8988
r ₄ = 12.931
d ₄ = 5.34
r ₅ = -10.100 (aspherical surface)
_{d 5 = 0.60 nd 3 = 1.69350} νd 3 = 53.20 PCt 3 = 0.8135
r ₆ = 24.955
_{d 6 = 1.41 nd 4 = 1.84666} νd 4 = 23.78 PCt 4 = 0.6600
r ₇ = -35.784
d ₇ = D (7) (variable)
r ₈ = ∞ (aperture stop)
d ₈ = D (8) (variable)
r ₉ = 11.750 (aspherical surface)
d ₉ = 3.87 nd ₅ = 1.55332 νd ₅ = 71.68 PCt ₅ = 0.8164
r ₁₀ = -18.393 (aspherical surface)
d ₁₀ = 0.15
r ₁₁ = 32.202
d ₁₁ = 0.50 nd ₆ = 1.62299 νd ₆ = 58.12 PCt ₆ = 0.8107
r ₁₂ = 9.700
_{d 12 = 4.73 nd 7 = 1.49700} νd 7 = 81.65 PCt 7 = 0.8305
r ₁₃ = -11.842
d ₁₃ = 0.15
r ₁₄ = 167.012
_{d 14 = 0.50 nd 8 = 1.80610} νd 8 = 40.73 PCt 8 = 0.7464
r ₁₅ = 7.822
_{d 15 = 4.27 nd 9 = 1.49700} νd 9 = 81.65 PCt 9 = 0.8305
r ₁₆ = -32.434
d ₁₆ = D (16) (variable)
r ₁₇ = -21.608 (aspherical surface)
d ₁₇ = 2.77 nd ₁₀ = 1.55332 νd ₁₀ = 71.68 PCt ₁₀ = 0.8164
r ₁₈ = -9.150
d ₁₈ = 0.50 nd ₁₁ = 1.84666 νd ₁₁ ＝ 23.78 PCt ₁₁ ＝ 0.6600
r ₁₉ = -14.586
d ₁₉ = 6.36
r ₂₀ = ∞
d ₂₀ = 0.50 nd ₁₂ = 1.51680 νd ₁₂ = 64.20 PCt ₁₂ = 0.8682
r ₂₁ = ∞
d ₂₁ = BF
r ₂₂ = ∞ (image plane)

Cone coefficient (k) and aspherical coefficient (A, B, C, D, E)
(5th surface)
k = 0,
A = 0, B = 9.65920 × 10 ^-5 , C = -1.19171 × 10 ^-5 ,
D = 9.17092 × 10 ^-7 , E = -2.98439 × 10 ^-8
(9th surface)
k = 0,
A = 0, B = -1.57570 × 10 ^-4 , C = 2.33471 × 10 ^-6 ,
D = 3.86574 × 10 ^-9 , E = -6.82758 × 10 ^-10
(10th surface)
k = 0,
A = 0, B = 2.76164 × 10 ^-4 , C = 1.16104 × 10 ^-6 ,
D = 6.71701 × 10 ^-8 , E = -1.34735 × 10 ^-9
(17th surface)
k = 0,
A = 0, B = 1.43511 x 10 ^-5 , C = 1.78962 x 10 ^-7 ,
D = 0, E = 0

(Various data)
Magnification ratio: 1.89
Wide-angle end Intermediate focal position Telephoto end focal length (at infinity object focused state) 4.43 5.83 8.36
F number 1.65 2.02 3.09
Half angle of view (ω) 66.72 48.20 32.79
Image height 4.75 4.75 4.75
Lens system total length 50.69 49.53 50.62
Back focus (BF) 2.00 2.00 2.00
D (7) 3.53 2.36 3.44
D (8) 7.97 5.45 0.85
D (16) 1.53 4.06 8.66

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 -5.89 2.25
2 9 11.09 -7.12
3 17 400.00 0.00

(Numerical value regarding conditional expression (1))
| F1 / fw | = 1.33

(Numerical value regarding conditional expression (2))
f23w (composite focal length of the second lens group G ₃₂ and the third lens group G _{33 in the in-} focus state of an object at infinity at the wide-angle end) = 11.78
f23w / fw = 2.66

(Numerical value regarding conditional expression (3))
| F3 / fw | = 90.25

(Numerical value regarding conditional expression (4))
| F23w / f1 | = 2.00

(Numerical value regarding conditional expression (5))
│νd3P-νd3n | = 47.9

(Numerical value regarding conditional expression (6))
νd2P_ave = 78.3

(Numerical value regarding conditional expression (7))
PCt_2n_i- (0.546 + 0.00467 × νd_2n_i) = 0.0102

(Numerical value regarding conditional expression (8))
νd1p = 23.8

(Numerical value regarding conditional expression (9))
PCt_1n_i- (0.546 + 0.00467 × νd_1n_i) = 0.0191

(Numerical value regarding conditional expression (10))
PCt_3n_i- (0.546 + 0.00467 × νd_3n_i) = 0.0029

(Numerical value regarding conditional expression (11))
| F1 / f2 | = 0.53

(Numerical value regarding conditional expression (12))
| X2 / f2 | = 0.64

(Numerical value regarding conditional expression (13))
f23t (composite focal length of the second lens group G ₃₂ and the third lens group G _{33 in the} object-focused state at infinity at the telephoto end) = 12.00
f23t / ft = 1.44

(Numerical value regarding conditional expression (14))
| F3 / f2 | = 36.08

  FIG. 7 is a diagram of various types of aberration of the zoom lens according to the third example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the g line (435.84 nm), and the long broken line is the IR line (850. The characteristic of the wavelength corresponding to (00 nm) is shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

FIG. 8 is a sectional view taken along the optical axis to show the configuration of the zoom lens according to the fourth example. This figure shows the in-focus state of an object at infinity at the wide-angle end of the lens system. This zoom lens comprises, in order from the object side, not shown, a first lens group G ₄₁ having a negative refractive power, a second lens group G ₄₂ having a positive refractive power, and a third lens group having a positive refractive power. G ₄₃ and are arranged. An aperture stop STP defining a predetermined aperture is arranged between the first lens group G ₄₁ and the second lens group G ₄₂ . A cover glass CG is arranged between the third lens group G ₄₃ and the image plane IMG.

The first lens group G ₄₁ includes, in order from the object side, a negative lens L ₄₁₁ , a negative lens L ₄₁₂ , a negative lens L _413, and a positive lens L ₄₁₄ . An aspherical surface is formed on the object side surface of the negative lens L ₄₁₃ . The negative lens L ₄₁₃ and the positive lens L ₄₁₄ are cemented together.

The second lens group G ₄₂ is configured by arranging a positive lens L ₄₂₁ , a negative lens L ₄₂₂ , a positive lens L ₄₂₃ , a negative lens L _424, and a positive lens L _{425 in this} order from the object side. .. Aspherical surfaces are formed on both surfaces of the positive lens L ₄₂₁ . The negative lens L ₄₂₂ and the positive lens L ₄₂₃ are cemented. The negative lens L ₄₂₄ and the positive lens L ₄₂₅ are cemented together.

The third lens group G ₄₃ is configured by sequentially arranging a positive lens L ₄₃₁ and a negative lens L ₄₃₂ from the object side. An aspherical surface is formed on the object side surface of the positive lens L ₄₃₁ . The positive lens L ₄₃₁ and the negative lens L ₄₃₂ are cemented together. The cemented surface between the positive lens L ₄₃₁ and the negative lens L ₄₃₂ has a convex shape on the image plane IMG side.

This zoom lens moves the first lens group G ₄₁ from the object side to the image surface IMG side along the optical axis while fixing the aperture stop STP and the third lens group G ₄₃ with respect to the image surface IMG. By moving the second lens group G ₄₂ along the optical axis from the image plane IMG side to the object side, zooming is performed from the wide-angle end to the telephoto end (see the solid line arrow in FIG. 8). Further, the first lens group G ₄₁ is moved along the optical axis from the object side to the image plane IMG side to perform focusing from the in-focus object state to the closest object state (in FIG. 8). See the dashed arrow).

  Hereinafter, various numerical data regarding the zoom lens according to the fourth embodiment will be shown.

(Surface data)
r ₁ = 63.338
d ₁ = 0.70 nd ₁ = 1.58913 νd ₁ ＝ 61.25 PCt ₁ ＝ 0.8368
r ₂ = 6.875
d ₂ = 2.83
r ₃ = 54.504
d ₃ = 0.50 nd ₂ = 1.76182 νd ₂ = 26.61 PCt ₂ = 0.6762
r ₄ = 15.319
d ₄ = 2.94
r ₅ = -13.227 (aspherical surface)
_{d 5 = 0.60 nd 3 = 1.62263} νd 3 = 58.16 PCt 3 = 0.8464
r ₆ = 13.671
_{d 6 = 1.99 nd 4 = 1.91082} νd 4 = 35.25 PCt 4 = 0.7131
r ₇ = -29.046
d ₇ = D (7) (variable)
r ₈ = ∞ (aperture stop)
d ₈ = D (8) (variable)
r ₉ = 10.260 (aspherical surface)
d ₉ = 3.74 nd ₅ = 1.55332 νd ₅ = 71.68 PCt ₅ = 0.8164
r ₁₀ = -16.500 (aspherical surface)
d ₁₀ = 0.74
r ₁₁ = -37.016
d ₁₁ = 0.50 nd ₆ = 1.56732 νd ₆ = 42.84 PCt ₆ = 0.7639
r ₁₂ = 61.389
_{d 12 = 3.40 nd 7 = 1.49700} νd 7 = 81.65 PCt 7 = 0.8305
r ₁₃ = -10.017
d ₁₃ = 0.15
r ₁₄ = 195.108
_{d 14 = 0.50 nd 8 = 1.80610} νd 8 = 40.73 PCt 8 = 0.7464
r ₁₅ = 7.000
_{d 15 = 3.73 nd 9 = 1.49700} νd 9 = 81.65 PCt 9 = 0.8305
r ₁₆ = -21.218
d ₁₆ = D (16) (variable)
r ₁₇ = -424.877 (aspherical surface)
d ₁₇ = 2.51 nd ₁₀ = 1.82080 νd ₁₀ = 42.71 PCt ₁₀ = 0.7536
r ₁₈ = -11.198
d ₁₈ = 0.50 nd ₁₁ = 1.72825 νd ₁₁ = 28.32 PCt ₁₁ = 0.6855
r ₁₉ = -153.514
d ₁₉ = 4.43
r ₂₀ = ∞
d ₂₀ = 0.50 nd ₁₂ = 1.51680 νd ₁₂ = 64.20 PCt ₁₂ = 0.8682
r ₂₁ = ∞
d ₂₁ = BF
r ₂₂ = ∞ (image plane)

Cone coefficient (k) and aspherical coefficient (A, B, C, D, E)
(5th surface)
k = 0,
A = 0, B = 1.61829 × 10 ^-5 , C = -3.79476 × 10 ^-6 ,
D = 1.79040 × 10 ^-7 , E = -4.30180 × 10 ^-9
(9th surface)
k = 0,
A = 0, B = -1.70485 × 10 ^-4 , C = 2.57665 × 10 ^-6 ,
D = 3.91896 × 10 ^-8 , E = -2.43028 × 10 ^-9
(10th surface)
k = 0,
A = 0, B = 4.38937 × 10 ^-4 , C = 4.74978 × 10 ^-8 ,
D = 2.06665 × 10 ^-7 , E = -4.60654 × 10 ^-9
(17th surface)
k = 0,
A = 0, B = -4.36169 × 10 ^-5 , C = -3.16374 × 10 ^-8 ,
D = 0, E = 0

(Various data)
Magnification ratio: 1.87
Wide-angle end Intermediate focal position Telephoto end focal length (at infinity object focused state) 4.45 6.10 8.33
F number 1.55 1.79 2.26
Half angle of view (ω) 66.34 45.39 32.52
Image height 4.75 4.75 4.75
Lens system total length 47.58 43.40 41.73
Back focus (BF) 2.00 2.00 2.00
D (7) 8.29 4.09 2.41
D (8) 5.87 3.76 0.85
D (16) 1.20 3.31 6.22

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 -9.74 5.88
2 9 11.52 -5.02
3 17 90.06 0.00

(Numerical value regarding conditional expression (1))
| F1 / fw | = 2.19

(Numerical value regarding conditional expression (2))
f23w (composite focal length of the second lens group G ₄₂ and the third lens group G _{43 in the in-} focus state at infinity at the wide-angle end) = 11.32
f23w / fw = 2.54

(Numerical value regarding conditional expression (3))
| F3 / fw | = 20.23

(Numerical value regarding conditional expression (4))
| F23w / f1 | = 1.16

(Numerical value regarding conditional expression (5))
│νd3P-νd3n | = 14.4

(Numerical value regarding conditional expression (6))
νd2P_ave = 78.3

(Numerical value regarding conditional expression (7))
PCt_2n_i- (0.546 + 0.00467 × νd_2n_i) = 0.0178

(Numerical value regarding conditional expression (8))
νd1p = 35.3

(Numerical value regarding conditional expression (9))
PCt_1n_i- (0.546 + 0.00467 × νd_1n_i) = 0.0288

(Numerical value regarding conditional expression (10))
PCt_3n_i- (0.546 + 0.00467 × νd_3n_i) = 0.0072

(Numerical value regarding conditional expression (11))
| F1 / f2 | = 0.85

(Numerical value regarding conditional expression (12))
| X2 / f2 | = 0.44

(Numerical value regarding conditional expression (13))
f23t (composite focal length of the second lens group G ₄₂ and the third lens group G _{43 in the in-} focus state at infinity at the telephoto end) = 11.98
f23t / ft = 1.44

(Numerical value regarding conditional expression (14))
| F3 / f2 | = 7.82

  FIG. 9 is a diagram of various types of aberration of the zoom lens according to the fourth example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the g line (435.84 nm), and the long broken line is the IR line (850. The characteristic of the wavelength corresponding to (00 nm) is shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

FIG. 10 is a sectional view taken along the optical axis showing the configuration of the zoom lens according to the fifth example. This figure shows the in-focus state of an object at infinity at the wide-angle end of the lens system. This zoom lens comprises, in order from the object side (not shown), a first lens group G ₅₁ having a negative refractive power, a second lens group G ₅₂ having a positive refractive power, and a third lens group having a positive refractive power. G ₅₃ and are arranged. An aperture stop STP that defines a predetermined aperture is arranged between the first lens group G ₅₁ and the second lens group G ₅₂ . A cover glass CG is arranged between the third lens group G ₅₃ and the image plane IMG.

The first lens group G ₅₁ includes a negative lens L ₅₁₁ , a negative lens L ₅₁₂ , a negative lens L _513, and a positive lens L ₅₁₄ , which are arranged in this order from the object side. An aspherical surface is formed on the object side surface of the negative lens L ₅₁₃ . The negative lens L ₅₁₃ and the positive lens L ₅₁₄ are cemented together.

The second lens group G ₅₂ is composed of, in order from the object side, a positive lens L ₅₂₁ , a negative lens L ₅₂₂ , a positive lens L ₅₂₃ , a negative lens L _524, and a positive lens L _525. . Aspherical surfaces are formed on both surfaces of the positive lens L ₅₂₁ . The negative lens L ₅₂₂ and the positive lens L ₅₂₃ are cemented together. The negative lens L ₅₂₄ and the positive lens L ₅₂₅ are cemented.

The third lens group G ₅₃ is configured by arranging a positive lens L ₅₃₁ and a negative lens L _{532 in this} order from the object side. An aspherical surface is formed on the object side surface of the positive lens L ₅₃₁ . The positive lens L ₅₃₁ and the negative lens L ₅₃₂ are cemented together. The cemented surface between the positive lens L ₅₃₁ and the negative lens L ₅₃₂ has a convex shape on the image plane IMG side.

This zoom lens moves the first lens group G ₅₁ along the optical axis from the object side to the image surface IMG side while keeping the aperture stop STP and the third lens group G ₅₃ fixed with respect to the image surface IMG. , The second lens group G ₅₂ is moved along the optical axis from the image plane IMG side to the object side to perform zooming from the wide-angle end to the telephoto end (see the solid arrow in FIG. 10). Further, the first lens group G ₅₁ is gently moved from the object side to the image plane IMG side along the optical axis to perform focusing from the infinity object focused state to the closest object focused state (FIG. 10). See the dashed arrow inside).

  Hereinafter, various numerical data regarding the zoom lens according to the fifth example will be shown.

(Surface data)
r ₁ = 22.840
d ₁ = 0.70 nd ₁ = 1.62299 νd ₁ = 58.12 PCt ₁ = 0.8107
r ₂ = 6.875
d ₂ = 2.32
r ₃ = 12.903
_{d 3 = 0.50 nd 2 = 1.48749} νd 2 = 70.45 PCt 2 = 0.8988
r ₄ = 7.319
d ₄ = 3.73
r ₅ = -13.671 (aspherical surface)
_{d 5 = 0.60 nd 3 = 1.62263} νd 3 = 58.16 PCt 3 = 0.8464
r ₆ = 8.019
d ₆ = 1.77 nd ₄ = 1.91082 νd ₄ = 35.25 PCt ₄ = 0.7131
r ₇ = 72.433
d ₇ = D (7) (variable)
r ₈ = ∞ (aperture stop)
d ₈ = D (8) (variable)
r ₉ = 12.789 (aspherical surface)
d ₉ = 3.50 nd ₅ = 1.59201 νd ₅ = 67.02 PCt ₅ = 0.8184
r ₁₀ = -18.012 (aspherical surface)
d ₁₀ = 0.15
r ₁₁ = 3031.500
d ₁₁ = 0.50 nd ₆ = 1.56732 νd ₆ = 42.84 PCt ₆ = 0.7639
r ₁₂ = 13.079
d ₁₂ = 4.07 nd ₇ = 1.59282 νd ₇ = 68.63 PCt ₇ = 0.7960
r ₁₃ = -10.671
d ₁₃ = 0.15
r ₁₄ = 47.455
d ₁₄ = 0.50 nd ₈ = 1.91082 νd ₈ = 35.25 PCt ₈ = 0.7131
r ₁₅ = 7.000
_{d 15 = 3.47 nd 9 = 1.49700} νd 9 = 81.65 PCt 9 = 0.8305
r ₁₆ = -39.000
d ₁₆ = D (16) (variable)
r ₁₇ = -96.750 (aspherical surface)
d ₁₇ = 2.52 nd ₁₀ = 1.88202 νd ₁₀ = 37.22 PCt ₁₀ = 0.7227
r ₁₈ = -13.905
_{d 18 = 0.50 nd 11 = 1.67270} νd 11 = 32.17 PCt 11 = 0.7030
r ₁₉ = -99.333
d ₁₉ = 4.38
r ₂₀ = ∞
d ₂₀ = 0.50 nd ₁₂ = 1.51680 νd ₁₂ = 64.20 PCt ₁₂ = 0.8682
r ₂₁ = ∞
d ₂₁ = BF
r ₂₂ = ∞ (image plane)

Cone coefficient (k) and aspherical coefficient (A, B, C, D, E)
(5th surface)
k = 0,
A = 0, B = -4.20167 × 10 ^-5 , C = -6.77937 × 10 ^-6 ,
D = 1.63124 × 10 ^-7 , E = -2.05645 × 10 ^-9
(9th surface)
k = 0,
A = 0, B = -2.65859 × 10 ^-4 , C = -3.36618 × 10 ^-6 ,
D = 1.22589 × 10 ^-7 , E = -7.65284 × 10 ^-9
(10th surface)
k = 0,
A = 0, B = 2.80382 × 10 ^-4 , C = -1.68536 × 10 ^-6 ,
D = 2.93515 x 10 ^-8 , E = -3.58703 x 10 ^-9
(17th surface)
k = 0,
A = 0, B = -2.21084 × 10 ^-5 , C = 7.95255 × 10 ^-8 ,
D = 0, E = 0

(Various data)
Magnification ratio: 1.87
Wide angle end Intermediate focal position Telephoto end focal length (at infinity object focused state) 4.44 6.16 8.34
F number 1.55 1.89 2.56
Half angle of view (ω) 66.62 44.71 32.43
Image height 4.75 4.75 4.75
Lens system total length 44.42 42.24 42.22
Back focus (BF) 2.00 2.00 2.00
D (7) 4.98 2.78 2.75
D (8) 6.38 3.93 0.85
D (16) 1.22 3.66 6.75

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 -7.84 2.23
2 9 10.13 -5.53
3 17 77.14 0.00

(Numerical value regarding conditional expression (1))
| F1 / fw | = 1.77

(Numerical value regarding conditional expression (2))
f23w (composite focal length of the second lens group G ₅₂ and the third lens group G _{53 in the in-} focus state of the object at infinity at the wide angle end) = 10.10.
f23w / fw = 2.28

(Numerical value regarding conditional expression (3))
｜ f3 / fw ｜ ＝ 17.39

(Numerical value regarding conditional expression (4))
| F23w / f1 | = 1.29

(Numerical value regarding conditional expression (5))
│νd3P-νd3n | = 5.1

(Numerical value regarding conditional expression (6))
νd2P_ave = 71.4

(Numerical value regarding conditional expression (7))
PCt_2n_i- (0.546 + 0.00467 × νd_2n_i) = 0.0178

(Numerical value regarding conditional expression (8))
νd1p = 35.3

(Numerical value regarding conditional expression (9))
PCt_1n_i- (0.546 + 0.00467 × νd_1n_i) = 0.0288

(Numerical value regarding conditional expression (10))
PCt_3n_i- (0.546 + 0.00467 × νd_3n_i) = 0.0068

(Numerical value regarding conditional expression (11))
| F1 / f2 | = 0.77

(Numerical value regarding conditional expression (12))
| X2 / f2 | = 0.55

(Numerical value regarding conditional expression (13))
f23t (composite focal length of the second lens group G ₅₂ and the third lens group G _{53 in the in-} focus state of the object at infinity at the telephoto end) = 10.88
f23t / ft = 1.30

(Numerical value regarding conditional expression (14))
| F3 / f2 | = 7.62

  FIG. 11 is a diagram of various types of aberration of the zoom lens according to the fifth example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the g line (435.84 nm), and the long broken line is the IR line (850. The characteristic of the wavelength corresponding to (00 nm) is shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

FIG. 12 is a sectional view taken along the optical axis showing the configuration of the zoom lens according to the sixth example. This figure shows the in-focus state of an object at infinity at the wide-angle end of the lens system. This zoom lens comprises, in order from the object side (not shown), a first lens group G ₆₁ having a negative refractive power, a second lens group G ₆₂ having a positive refractive power, and a third lens group having a positive refractive power. G ₆₃ and are arranged. An aperture stop STP that defines a predetermined aperture is arranged between the first lens group G ₆₁ and the second lens group G ₆₂ . A cover glass CG is arranged between the third lens group G ₆₃ and the image plane IMG.

The first lens group G ₆₁ includes, in order from the object side, a negative lens L ₆₁₁ , a negative lens L ₆₁₂ , a negative lens L _613, and a positive lens L ₆₁₄ . An aspherical surface is formed on the object side surface of the negative lens L ₆₁₃ . The negative lens L ₆₁₃ and the positive lens L ₆₁₄ are cemented together.

The second lens group G ₆₂ includes a positive lens L ₆₂₁ , a negative lens L ₆₂₂ , a positive lens L ₆₂₃ , a negative lens L _624, and a positive lens L ₆₂₅ , which are arranged in this order from the object side. .. Aspherical surfaces are formed on both surfaces of the positive lens L ₆₂₁ . The negative lens L ₆₂₂ and the positive lens L ₆₂₃ are cemented together. The negative lens L ₆₂₄ and the positive lens L ₆₂₅ are cemented together.

The third lens group G ₆₃ is configured by arranging a positive lens L ₆₃₁ and a negative lens L _{632 in this} order from the object side. An aspherical surface is formed on the object side surface of the positive lens L ₆₃₁ . The positive lens L ₆₃₁ and the negative lens L ₆₃₂ are cemented together. The cemented surface between the positive lens L ₆₃₁ and the negative lens L ₆₃₂ has a convex shape on the image plane IMG side.

This zoom lens moves the first lens group G ₆₁ gently along the optical axis from the object side to the image surface IMG side while keeping the aperture stop STP and the third lens group G ₆₃ fixed with respect to the image surface IMG. , The second lens group G ₆₂ is moved along the optical axis from the image plane IMG side to the object side to perform zooming from the wide-angle end to the telephoto end (see the solid arrow in FIG. 12). Further, the first lens group G ₆₁ is gently moved from the object side to the image plane IMG side along the optical axis to perform focusing from the infinity object focus state to the closest object focus state (FIG. 12). See the dashed arrow inside).

  Hereinafter, various numerical data regarding the zoom lens according to the sixth embodiment will be shown.

(Surface data)
r ₁ = 29.683
d ₁ = 0.70 nd ₁ = 1.88300 νd ₁ ＝ 40.80 PCt ₁ ＝ 0.7381
r ₂ = 6.875
d ₂ = 3.36
r ₃ = 85.894
_{d 3 = 0.50 nd 2 = 1.48749} νd 2 = 70.45 PCt 2 = 0.8988
r ₄ = 15.316
d ₄ = 3.44
r ₅ = -11.913 (aspherical surface)
_{d 5 = 0.60 nd 3 = 1.62263} νd 3 = 58.16 PCt 3 = 0.8464
r ₆ = 12.850
d ₆ = 3.45 nd ₄ = 1.91082 νd ₄ = 35.25 PCt ₄ = 0.7131
r ₇ = -30.637
d ₇ = D (7) (variable)
r ₈ = ∞ (aperture stop)
d ₈ = D (8) (variable)
r ₉ = 12.164 (aspherical surface)
d ₉ = 4.00 nd ₅ = 1.59201 νd ₅ = 67.02 PCt ₅ = 0.8499
r ₁₀ = -18.102 (aspherical surface)
d ₁₀ = 1.52
r ₁₁ = -778.309
d ₁₁ = 0.50 nd ₆ = 1.56883 νd ₆ = 56.04 PCt ₆ = 0.8080
r ₁₂ = 9.700
_{d 12 = 3.88 nd 7 = 1.49700} νd 7 = 81.65 PCt 7 = 0.8305
r ₁₃ = -13.485
d ₁₃ = 0.16
r ₁₄ = 288.955
d ₁₄ = 0.50 nd ₈ = 1.91082 νd ₈ = 35.25 PCt ₈ = 0.7131
r ₁₅ = 8.053
_{d 15 = 3.50 nd 9 = 1.49700} νd 9 = 81.65 PCt 9 = 0.8305
r ₁₆ = -20.581
d ₁₆ = D (16) (variable)
r ₁₇ = -20.841 (aspherical surface)
d ₁₇ = 2.79 nd ₁₀ = 1.82080 νd ₁₀ = 42.71 PCt ₁₀ = 0.7536
r ₁₈ = -9.150
d ₁₈ = 0.50 nd ₁₁ = 1.91082 νd ₁₁ = 35.25 PCt ₁₁ = 0.7131
r ₁₉ = -14.353
d ₁₉ = 4.00
r ₂₀ = ∞
d ₂₀ = 0.50 nd ₁₂ = 1.51680 νd ₁₂ = 64.20 PCt ₁₂ = 0.8682
r ₂₁ = ∞
d ₂₁ = BF
r ₂₂ = ∞ (image plane)

Cone coefficient (k) and aspherical coefficient (A, B, C, D, E)
(5th surface)
k = 0,
A = 0, B = -1.06724 × 10 ^-5 , C = -2.37407 × 10 ^-6 ,
D = 7.20137 x 10 ^-8 , E = -1.81348 x 10 ^-9
(9th surface)
k = 0,
A = 0, B = -1.07086 × 10 ^-4 , C = 1.71366 × 10 ^-6 ,
D = -2.23618 × 10 ^-8 , E = 4.85325 × 10 ^-10
(10th surface)
k = 0,
A = 0, B = 2.35304 × 10 ^-4 , C = 7.93066 × 10 ^-7 ,
D = -7.58119 × 10 ^-10 , E = 4.17355 × 10 ^-10
(17th surface)
k = 0,
A = 0, B = -1.87934 × 10 ^-5 , C = 1.51794 × 10 ^-7 ,
D = 0, E = 0

(Various data)
Magnification ratio: 1.88
Wide-angle end Intermediate focal position Telephoto end focal length (at infinity object focused state) 4.43 5.83 8.35
F number 1.65 1.91 2.58
Half angle of view (ω) 66.04 47.83 32.80
Image height 4.75 4.75 4.75
Lens system total length 56.18 52.70 51.30
Back focus (BF) 2.00 2.00 2.00
D (7) 8.95 5.44 4.04
D (8) 7.27 4.97 0.85
D (16) 4.10 6.40 10.52

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 -8.44 4.91
2 9 13.22 -6.42
3 17 54.65 0.00

(Numerical value regarding conditional expression (1))
| F1 / fw | = 1.90

(Numerical value regarding conditional expression (2))
f23w (composite focal length of the second lens group G ₆₂ and the third lens group G _{63 in the in-} focus state of an object at infinity at the wide-angle end) = 14.51
f23w / fw = 3.27

(Numerical value regarding conditional expression (3))
| F3 / fw | = 12.33

(Numerical value regarding conditional expression (4))
| F23w / f1 | = 1.72

(Numerical value regarding conditional expression (5))
│νd3P-νd3n | = 7.5

(Numerical value regarding conditional expression (6))
νd2P_ave = 76.8

(Numerical value regarding conditional expression (7))
PCt_2n_i- (0.546 + 0.00467 × νd_2n_i) = 0.0025

(Numerical value regarding conditional expression (8))
νd1p = 35.3

(Numerical value regarding conditional expression (9))
PCt_1n_i- (0.546 + 0.00467 × νd_1n_i) = 0.0288

(Numerical value regarding conditional expression (10))
PCt_3n_i- (0.546 + 0.00467 × νd_3n_i) = 0.0025

(Numerical value regarding conditional expression (11))
| F1 / f2 | = 0.64

(Numerical value regarding conditional expression (12))
｜ X2 / f2 | = 0.49

(Numerical value regarding conditional expression (13))
f23t (composite focal length of the second lens group G ₆₂ and the third lens group G _{63 in the in-} focus state of an object at infinity at the telephoto end) = 16.65
f23t / ft = 2.00

(Numerical value regarding conditional expression (14))
| F3 / f2 | = 4.13

  FIG. 13 is a diagram of various types of aberration of the zoom lens according to the sixth example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the g line (435.84 nm), and the long broken line is the IR line (850. The characteristic of the wavelength corresponding to (00 nm) is shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

FIG. 14 is a sectional view taken along the optical axis to show the configuration of the zoom lens according to the seventh example. This figure shows the in-focus state of an object at infinity at the wide-angle end of the lens system. This zoom lens comprises, in order from the object side, not shown, a first lens group G ₇₁ having a negative refractive power, a second lens group G ₇₂ having a positive refractive power, and a third lens group having a positive refractive power. G ₇₃ and are arranged. An aperture stop STP that defines a predetermined aperture is arranged between the first lens group G ₇₁ and the second lens group G ₇₂ . A cover glass CG is arranged between the third lens group G ₇₃ and the image plane IMG.

The first lens group G ₇₁ includes, in order from the object side, a negative lens L ₇₁₁ , a negative lens L ₇₁₂ , a negative lens L _713, and a positive lens L ₇₁₄ . An aspherical surface is formed on the object side surface of the negative lens L ₇₁₃ . The negative lens L ₇₁₃ and the positive lens L ₇₁₄ are cemented together.

The second lens group G ₇₂ is configured by sequentially arranging a positive lens L ₇₂₁ , a negative lens L ₇₂₂ , a positive lens L ₇₂₃ , a negative lens L _724, and a positive lens L ₇₂₅ from the object side. .. Aspherical surfaces are formed on both surfaces of the positive lens L ₇₂₁ . The negative lens L ₇₂₂ and the positive lens L ₇₂₃ are cemented. The negative lens L ₇₂₄ and the positive lens L ₇₂₅ are cemented.

The third lens group G ₇₃ is configured by arranging a positive lens L ₇₃₁ and a negative lens L _{732 in this} order from the object side. An aspherical surface is formed on the object side surface of the positive lens L ₇₃₁ . The positive lens L ₇₃₁ and the negative lens L ₇₃₂ are cemented together. The cemented surface between the positive lens L ₇₃₁ and the negative lens L ₇₃₂ has a convex shape on the image plane IMG side.

This zoom lens moves the first lens group G ₇₁ gently from the object side to the image plane IMG side along the optical axis while fixing the aperture stop STP and the third lens group G ₇₃ with respect to the image plane IMG. , The second lens group G ₇₂ is moved along the optical axis from the image plane IMG side to the object side to perform zooming from the wide-angle end to the telephoto end (see the solid arrow in FIG. 14). Further, the first lens group G ₇₁ is gently moved from the object side to the image plane IMG side along the optical axis to perform focusing from the infinity object focused state to the closest object focused state (FIG. 14). See the dashed arrow inside).

  Hereinafter, various numerical data relating to the zoom lens according to the example 7 will be shown.

(Surface data)
r ₁ = 36.110
d ₁ = 0.70 nd ₁ = 1.88300 νd ₁ ＝ 40.80 PCt ₁ ＝ 0.7381
r ₂ = 6.875
d ₂ = 3.49
r ₃ = 269.543
_{d 3 = 0.50 nd 2 = 1.48749} νd 2 = 70.45 PCt 2 = 0.8988
r ₄ = 14.782
d ₄ = 3.23
r ₅ = -18.843 (aspherical surface)
_{d 5 = 0.60 nd 3 = 1.62263} νd 3 = 58.16 PCt 3 = 0.8464
r ₆ = 11.664
d ₆ = 3.36 nd ₄ = 1.91082 νd ₄ = 35.25 PCt ₄ = 0.7131
r ₇ = -44.582
d ₇ = D (7) (variable)
r ₈ = ∞ (aperture stop)
d ₈ = D (8) (variable)
r ₉ = 12.085 (aspherical surface)
d ₉ = 4.00 nd ₅ = 1.59201 νd ₅ = 67.02 PCt ₅ = 0.8499
r ₁₀ = -19.491 (aspherical surface)
d ₁₀ = 1.36
r ₁₁ = 309.911
d ₁₁ = 0.50 nd ₆ = 1.56883 νd ₆ = 56.04 PCt ₆ = 0.8080
r ₁₂ = 10.063
_{d 12 = 3.87 nd 7 = 1.49700} νd 7 = 81.65 PCt 7 = 0.8305
r ₁₃ = -13.895
d ₁₃ = 0.36
r ₁₄ = 929.336
d ₁₄ = 0.50 nd ₈ = 1.91082 νd ₈ = 35.25 PCt ₈ = 0.7131
r ₁₅ = 7.835
_{d 15 = 3.77 nd 9 = 1.49700} νd 9 = 81.65 PCt 9 = 0.8305
r ₁₆ = -21.378
d ₁₆ = D (16) (variable)
r ₁₇ = -22.644 (aspherical surface)
d ₁₇ = 2.81 nd ₁₀ = 1.82080 νd ₁₀ = 42.71 PCt ₁₀ = 0.7536
r ₁₈ = -9.159
d ₁₈ = 0.50 nd ₁₁ = 1.91082 νd ₁₁ = 35.25 PCt ₁₁ = 0.7131
r ₁₉ = -14.459
d ₁₉ = 4.00
r ₂₀ = ∞
d ₂₀ = 0.50 nd ₁₂ = 1.51680 νd ₁₂ = 64.20 PCt ₁₂ = 0.8682
r ₂₁ = ∞
d ₂₁ = BF
r ₂₂ = ∞ (image plane)

Cone coefficient (k) and aspherical coefficient (A, B, C, D, E)
(5th surface)
k = 0,
A = 0, B = 1.62760 × 10 ^-5 , C = -1.42083 × 10 ^-6 ,
D = 6.60166 × 10 ^-8 , E = -8.80582 × 10 ^-10
(9th surface)
k = 0,
A = 0, B = -1.02549 × 10 ^-4 , C = 1.52216 × 10 ^-6 ,
D = -2.31244 × 10 ^-8 , E = 3.62557 × 10 ^-10
(10th surface)
k = 0,
A = 0, B = 2.17744 × 10 ^-4 , C = 9.00649 × 10 ^-7 ,
D = -8.24436 × 10 ^-9 , E = 3.18041 × 10 ^-10
(17th surface)
k = 0,
A = 0, B = -3.48413 × 10 ^-5 , C = -3.50512 × 10 ^-8 ,
D = 0, E = 0

(Various data)
Magnification ratio: 1.88
Wide-angle end Intermediate focal position Telephoto end focal length (at infinity object focused state) 4.42 5.82 8.33
F number 1.65 1.91 2.57
Half angle of view (ω) 64.86 47.51 32.69
Image height 4.75 4.75 4.75
Lens system total length 57.42 53.69 52.09
Back focus (BF) 2.00 2.00 2.00
D (7) 10.06 6.33 4.73
D (8) 7.35 5.02 0.85
D (16) 3.95 6.28 10.45

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 -8.74 5.33
2 9 13.59 -6.50
3 17 48.39 0.00

(Numerical value regarding conditional expression (1))
| F1 / fw | = 1.98

(Numerical value regarding conditional expression (2))
f23w (composite focal length of the second lens group G ₇₂ and the third lens group G _{73 in the in-} focus state of the object at infinity at the wide-angle end) = 14.85
f23w / fw = 3.36

(Numerical value regarding conditional expression (3))
| F3 / fw | = 10.95

(Numerical value regarding conditional expression (4))
| F23w / f1 | = 1.70

(Numerical value regarding conditional expression (5))
│νd3P-νd3n | = 7.5

(Numerical value regarding conditional expression (6))
νd2P_ave = 76.8

(Numerical value regarding conditional expression (7))
PCt_2n_i- (0.546 + 0.00467 × νd_2n_i) = 0.0025

(Numerical value regarding conditional expression (8))
νd1p = 35.3

(Numerical value regarding conditional expression (9))
PCt_1n_i- (0.546 + 0.00467 × νd_1n_i) = 0.0288

(Numerical value regarding conditional expression (10))
PCt_3n_i- (0.546 + 0.00467 × νd_3n_i) = 0.0025

(Numerical value regarding conditional expression (11))
| F1 / f2 | = 0.64

(Numerical value regarding conditional expression (12))
｜ X2 / f2 | = 0.48

(Numerical value regarding conditional expression (13))
f23t (composite focal length of the second lens group G ₇₂ and the third lens group G ₇₃ at the telephoto end) = 17.40
f23t / ft = 2.09

(Numerical value regarding conditional expression (14))
| F3 / f2 | = 3.56

  FIG. 15 is a diagram of various types of aberration of the zoom lens according to the seventh example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (λ = 587.56 nm), the short broken line is the g line (λ = 435.84 nm), and the long broken line is IR. The characteristic of the wavelength corresponding to the line (λ = 850.00 nm) is shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the diagram of astigmatism, the solid line shows the characteristics of the sagittal plane (indicated by S in the figure) and the broken line shows the characteristics of the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line.

FIG. 16 is a cross-sectional view taken along the optical axis, showing the configuration of the zoom lens according to the eighth example. This figure shows the in-focus state of an object at infinity at the wide-angle end of the lens system. This zoom lens comprises, in order from the object side (not shown), a first lens group G ₈₁ having a negative refractive power, a second lens group G ₈₂ having a positive refractive power, and a third lens group having a negative refractive power. _G83 and are arranged. An aperture stop STP defining a predetermined aperture is arranged between the first lens group G ₈₁ and the second lens group G ₈₂ . A cover glass CG is arranged between the third lens group G ₈₃ and the image plane IMG.

The first lens group G ₈₁ includes, in order from the object side, a negative lens L ₈₁₁ , a negative lens L ₈₁₂ , a negative lens L _813, and a positive lens L ₈₁₄ . An aspherical surface is formed on the object side surface of the negative lens L ₈₁₃ . The negative lens L ₈₁₃ and the positive lens L ₈₁₄ are cemented together.

The second lens group G ₈₂ is configured by arranging a positive lens L ₈₂₁ , a negative lens L ₈₂₂ , a positive lens L ₈₂₃ , a negative lens L _824, and a positive lens L _{825 in this} order from the object side. .. Aspherical surfaces are formed on both surfaces of the positive lens L ₈₂₁ . The negative lens L ₈₂₂ and the positive lens L ₈₂₃ are cemented. The negative lens L ₈₂₄ and the positive lens L ₈₂₅ are cemented together.

The third lens group G ₈₃ is composed of a positive lens L ₈₃₁ and a negative lens L ₈₃₂ arranged in order from the object side. Aspherical surfaces are formed on both surfaces of the positive lens L ₈₃₁ .

In this zoom lens, the first lens group G ₈₁ forms a convex locus along the optical axis on the image plane IMG side while the aperture stop STP and the third lens group G ₈₃ are fixed with respect to the image plane IMG. And the second lens group G ₈₂ is moved along the optical axis from the image plane IMG side to the object side to perform zooming from the wide-angle end to the telephoto end (see the solid arrow in FIG. 16). .. Further, the first lens group G ₈₁ is moved along the optical axis so as to form a locus of a gentle convex toward the image plane IMG side to perform focusing from the infinity object focus state to the closest object focus state. (Refer to the broken arrow in FIG. 16).

  Hereinafter, various numerical data regarding the zoom lens according to the eighth example will be shown.

(Surface data)
r ₁ = 21.133
_{d 1 = 0.70 nd 1 = 1.63854} νd 1 = 55.45 PCt 1 = 0.7991
r ₂ = 6.875
d ₂ = 2.69
r ₃ = 9.922
_{d 3 = 0.50 nd 2 = 1.88300} νd 2 = 40.80 PCt 2 = 0.7381
r ₄ = 6.150
d ₄ = 3.97
r ₅ = -11.017 (aspherical surface)
_{d 5 = 0.60 nd 3 = 1.62263} νd 3 = 58.16 PCt 3 = 0.8464
r ₆ = 7.873
_{d 6 = 1.74 nd 4 = 1.91082} νd 4 = 35.25 PCt 4 = 0.7131
r ₇ = 67.749
d ₇ = D (7) (variable)
r ₈ = ∞ (aperture stop)
d ₈ = D (8) (variable)
r ₉ = 11.518 (aspherical surface)
d ₉ = 4.00 nd ₅ = 1.55332 νd ₅ = 71.68 PCt ₅ = 0.8164
r ₁₀ = -16.500 (aspherical surface)
d ₁₀ = 0.15
r ₁₁ = 32.578
_{d 11 = 0.50 nd 6 = 1.88300} νd 6 = 40.80 PCt 6 = 0.7381
r ₁₂ = 19.905
_{d 12 = 3.90 nd 7 = 1.49700} νd 7 = 81.65 PCt 7 = 0.8305
r ₁₃ = -11.291
d ₁₃ = 0.15
r ₁₄ = -238.272
_{d 14 = 0.50 nd 8 = 1.80610} νd 8 = 40.73 PCt 8 = 0.7464
r ₁₅ = 7.799
_{d 15 = 4.36 nd 9 = 1.49700} νd 9 = 81.65 PCt 9 = 0.8305
r ₁₆ = -17.677
d ₁₆ = D (16) (variable)
r ₁₇ = -21.317 (aspherical surface)
d ₁₇ = 2.82 nd ₁₀ = 1.49710 νd ₁₀ ＝ 81.56 PCt ₁₀ ＝ 0.8349
r ₁₈ = -9.150 (aspherical surface)
d ₁₈ = 0.30
r ₁₉ = -8.426
d ₁₉ = 0.50 nd ₁₁ = 1.90366 νd ₁₁ = 31.32 PCt ₁₁ = 0.6968
r ₂₀ = -13.212
d ₂₀ = 6.04
r ₂₁ = ∞
d ₂₁ = 0.50 nd ₁₂ = 1.51680 νd ₁₂ = 64.20 PCt ₁₂ = 0.8682
r ₂₁ = ∞
d ₂₁ = BF
r ₂₂ = ∞ (image plane)

Cone coefficient (k) and aspherical coefficient (A, B, C, D, E)
(5th surface)
k = 0,
A = 0, B = -3.75950 × 10 ^-5 , C = -1.72154 × 10 ^-5 ,
D = 9.06529 × 10 ^-7 , E = -2.94817 × 10 ^-8
(9th surface)
k = 0,
A = 0, B = -1.77587 × 10 ^-4 , C = 2.23866 × 10 ^-6 ,
D = 1.17470 × 10 ^-8 , E = -1.15419 × 10 ^-9
(10th surface)
k = 0,
A = 0, B = 3.51196 × 10 ^-4 , C = 1.23946 × 10 ^-6 ,
D = 8.50737 × 10 ^-8 , E = -1.85413 × 10 ^-9
(17th surface)
k = 0,
A = 0, B = 2.94890 × 10 ^-5 , C = 1.18346 × 10 ^-6 ,
D = 0, E = 0
(Eighteenth surface)
k = 0,
A = 0, B = -4.83274 × 10 ^-5 , C = -5.27841 × 10 ^-8 ,
D = 0, E = 0

(Various data)
Magnification ratio: 1.88
Wide-angle end Intermediate focal position Telephoto end focal length (at infinity object focused state) 4.43 5.83 8.35
F number 1.65 2.00 3.06
Half angle of view (ω) 65.46 47.68 32.57
Image height 4.75 4.75 4.75
Lens system total length 48.26 47.11 48.05
Back focus (BF) 2.00 2.00 2.00
D (7) 3.68 2.53 3.47
D (8) 7.47 5.14 0.85
D (16) 1.20 3.53 7.82

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 -5.65 2.10
2 9 10.41 -6.62
3 17 -186.14 0.00

(Numerical value regarding conditional expression (1))
| F1 / fw | = 1.27

(Numerical value regarding conditional expression (2))
f23w (composite focal length of the second lens group G ₈₂ and the third lens group G _{83 in the in-} focus state of an object at infinity at the wide-angle end) = 10.96
f23w / fw = 2.47

(Numerical value regarding conditional expression (3))
| F3 / fw | = 41.97

(Numerical value regarding conditional expression (4))
| F23w / f1 | = 1.94

(Numerical value regarding conditional expression (5))
│νd3P-νd3n | = 50.2

(Numerical value regarding conditional expression (6))
νd2P_ave = 78.3

(Numerical value regarding conditional expression (7))
PCt_2n_i- (0.546 + 0.00467 × νd_2n_i) = 0.0102

(Numerical value regarding conditional expression (8))
νd1p = 35.3

(Numerical value regarding conditional expression (9))
PCt_1n_i- (0.546 + 0.00467 × νd_1n_i) = 0.0288

(Numerical value regarding conditional expression (10))
PCt_3n_i- (0.546 + 0.00467 × νd_3n_i) = 0.0045

(Numerical value regarding conditional expression (11))
| F1 / f2 | = 0.54

(Numerical value regarding conditional expression (12))
| X2 / f2 | = 0.64

(Numerical value regarding conditional expression (13))
f23t (composite focal length of the second lens unit G ₈₂ and the third lens unit G _{83 in the in-} focus state at infinity at the telephoto end) = 10.57
f23t / ft = 1.27

(Numerical value regarding conditional expression (14))
| F3 / f2 | = 17.88

  FIG. 17 is a diagram of various types of aberration of the zoom lens according to the eighth example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the g line (435.84 nm), and the long broken line is the IR line (850. The characteristic of the wavelength corresponding to (00 nm) is shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

In the numerical data in each of the above-mentioned embodiments, r ₁ , r ₂ , ... Are radii of curvature of the lens surface and the like, d ₁ , d ₂ ,. , Nd ₁ , nd ₂ , ... Denote the refractive index for the d line (λ = 587.56 nm) of the lens or the like, and νd ₁ , νd ₂ , ... Are the d line of the lens (λ = 587. 56 nm), Abbe numbers, PCt ₁ , PCt ₂ , ... Show the partial dispersion ratios for the C line and t line of the lens or the like. The unit of length is “mm” and the unit of angle is “°”.

  In each of the aspherical shapes, the height in the direction perpendicular to the optical axis is H, the amount of displacement in the optical axis direction at the height H when the lens surface apex is the origin is X (H), and the paraxial radius of curvature is Is R, the conic coefficient is k, the second-order, fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients are A, B, C, D, and E, respectively, and when the traveling direction of light is positive, It is represented by the formula shown in.

  As shown in each of the above embodiments, according to the present invention, by satisfying each of the above conditional expressions, a solid-state imaging device having a large aperture ratio, high pixels, and high sensitivity while having a simple configuration. It has a high optical performance that is compatible with all types, and is capable of correcting various aberrations that occur for light with a wide range of wavelengths from the visible light region to the near-infrared region satisfactorily over the entire zoom range. The zoom lens can be realized.

  The zoom lens having such characteristics can be used not only in a camera for photography that mainly uses light in the visible light range, but also in various imaging devices such as a surveillance camera that also performs nighttime shooting. In particular, it is suitable for an image pickup apparatus including a solid-state image pickup element with high pixels and high sensitivity.

<Application example>
Next, an example in which the zoom lens according to the present invention is applied to an image pickup apparatus will be shown. FIG. 18 is a diagram showing an example of an image pickup apparatus including a zoom lens according to the present invention. As shown in FIG. 18, the image pickup apparatus 100 includes a zoom lens 10, a lens barrel 20, and a solid-state image pickup element 101. The zoom lens 10 is housed in a lens barrel 20, and zooming and zooming are executed by driving a driving mechanism (not shown). In FIG. 18, the zoom lens 10 according to the first embodiment (see FIG. 2) is shown, but the zoom lenses according to the second to eighth embodiments can be similarly mounted on the image pickup apparatus 100. ..

  In the image pickup apparatus 100 including the zoom lens 10 and the solid-state image pickup element 101, the image plane IMG shown in FIG. 2 corresponds to the image pickup surface of the solid-state image pickup element 101. As the solid-state imaging device 101, for example, a photoelectric conversion device such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) sensor can be used.

  In the imaging device 100, the light incident from the object side of the zoom lens 10 finally forms an image on the imaging surface of the solid-state imaging device 101. Then, the solid-state imaging device 101 photoelectrically converts the received light and outputs it as an electric signal. This output signal is arithmetically processed by a signal processing circuit (not shown) to generate a digital image corresponding to the object image. The digital image can be recorded in a recording medium such as an HDD (Hard Disk Drive), a memory card, an optical disk, or a magnetic tape.

  By configuring as described above, it becomes possible to satisfactorily correct various aberrations that occur with respect to light having a wide range of wavelengths from the visible light region to the near infrared region over the entire zooming range, and change the day and night. Regardless, it is possible to realize a high-performance image pickup device that can obtain a good image.

  FIG. 18 shows an example in which the zoom lens according to the present invention is used in a surveillance camera. However, the zoom lens according to the present invention can be used not only for surveillance cameras but also for video cameras, digital still cameras, single-lens reflex cameras, mirrorless single-lens cameras, and the like.

  As described above, the zoom lens according to the present invention is useful for a small-sized image pickup device equipped with a solid-state image pickup device such as a CCD or CMOS, and is particularly suitable for an image pickup device that requires high optical performance.

G ₁₁ , G ₂₁ , G ₃₁ , G ₄₁ , G ₅₁ , G ₆₁ , G ₇₁ , G ₈₁ First lens group G ₁₂ , G ₂₂ , G ₃₂ , G ₄₂ , G ₅₂ , G ₆₂ , G ₇₂ , G ₈₂ the second lens group _{G 13, G 23, G 33} , G 43, G 53, G 63, G 73, G 83 third lens group _{L 111, L 112, L 113} , L 122, L 124, L 132, L ₂₁₁ , L ₂₁₂ , L ₂₂₂ , L ₂₂₄ , L ₂₃₂ , L ₃₁₁ , L ₃₁₂ , L ₃₁₃ , L ₃₂₂ , L ₃₂₄ , L ₃₃₂ , L ₄₁₁ , L ₄₁₂ , L ₄₁₃ , L ₄₂₂ , L ₄₂₄ , L ₄₃₂ , L ₅₁₁ , L ₅₁₂ , L ₅₁₃ , L ₅₂₂ , L ₅₂₄ , L ₅₃₂ , L ₆₁₁ , L ₆₁₂ , L ₆₁₃ , L ₆₂₂ , L ₆₂₄ , L ₆₃₂ , L ₇₁₁ , L ₇₁₂ , L ₇₁₃ , L ₇₂₂ , L ₇₂₄ , L ₇₃₂ , L ₈₁₁ , L ₈₁₂ , L ₈₁₃ , L ₈₂₂ , L ₈₂₄ , L ₈₃₂ negative lens L ₁₁₄ , L ₁₂₁ , L ₁₂₃ , L ₁₂₅ , L ₁₃₁ , L ₂₁₃ , L ₂₂₁ , L ₂₂₃ , L ₂₂₅ , L ₂₃₁ , L ₃₁₄ , L ₃₂₁ , L ₃₂₃ , L ₃₂₅ , L ₃₃₁ , L ₄₁₄ , L ₄₂₁ , L ₄₂₃ , L ₄₂₅ , L ₄₃₁ , L ₅₁₄ , L ₅₂₁ , L ₅₂₃ , L ₅₂₅ , L ₅₃₁ , L ₆₁₄ , L ₆₂₁ , L ₆₂₃ , L ₆₂₅ , L ₆₃₁ , L ₇₁₄ , L ₇₂₁ , L ₇₂₃ , L ₇₂₅ , L ₇₃₁ , L ₈₁₄ , L ₈₂₁ , L ₈₂₃ , L ₈₂₅ , L ₈₃₁ Positive lens STP aperture stop CG cover glass IMG image plane 10 zoom lens 20 lens barrel 100 imaging device 101 solid-state imaging device

Claims (11)

It is composed of a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group, which are arranged in order from the object side.
A zoom lens for performing zooming from a wide-angle end to a telephoto end by moving at least the first lens group and the second lens group along an optical axis to change a distance between the lens groups on the optical axis. ,
A positive lens is disposed on the most object side of the second lens group,
The third lens group includes at least one positive lens and at least one negative lens,
A zoom lens characterized by satisfying the following conditional expression.
(1) 1.2 ≦ | f1 / fw | ≦ 2.5
(2) 2.0 ≦ f23w / fw ≦ 3.4
(3) 10 ≦ | f3 / fw | ≦ 200
(6) 65.0 ≦ νd2P_ave
(11) 0.4 ≦ | f1 / f2 | ≦ 0.77
Here, f1 is the focal length of the first lens group, fw is the focal length of the entire lens system at the wide-angle end when the object is focused at infinity, and f23w is the second lens group when the object is focused at infinity at the wide-angle end. F3 is a focal length of the third lens group, νd2P_ave is an average value of Abbe numbers for d lines of all positive lenses included in the second lens group, and f2 is the above The focal length of the second lens group is shown. An aperture stop is arranged between the first lens group and the second lens group,
The zoom lens according to claim 1, wherein the aperture stop and the third lens group are fixed during zooming from the wide-angle end to the telephoto end. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
(4) 1.1 ≦ | f23w / f1 | ≦ 2.1 The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression.
(5) 5.0 ≦ | νd3P−νd3n |
Here, νd3P is the Abbe number for the d-line of at least one positive lens included in the third lens group, and νd3n is the Abbe number for the d-line of at least one negative lens included in the third lens group. Show. The second lens group includes at least one negative lens,
The zoom lens according to any one of claims 1 to 4, wherein the following conditional expression is satisfied.
(7) 0.000 ≦ PCt_2n_i− (0.546 + 0.00467 × νd_2n_i)
Here, PCt_2n_i represents a partial dispersion ratio of at least one negative lens included in the second lens group with respect to C line and t line, and νd_2n_i represents an Abbe number for the d line of the negative lens for which the value of PCt_2n_i was calculated. .. The first lens group includes at least one positive lens and at least two negative lenses,
The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression.
(8) νd1p ≦ 40.0
(9) 0.000≤PCt_1n_i- (0.546 + 0.00467 × νd_1n_i)
Where νd1p is the Abbe number of at least one positive lens included in the first lens group with respect to the d-line, and PCt_1n_i is the C-line and t-line of at least one negative lens included in the first lens group. The partial dispersion ratio, νd_1n_i, indicates the Abbe number for the d-line of the negative lens for which the value of PCt_1n_i has been calculated. The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expressions.
(10) 0.000 ≦ PCt — 3n_i− (0.546 + 0.00467 × νd — 3n_i)
Here, PCt_3n_i represents a partial dispersion ratio of at least one negative lens included in the third lens group with respect to the C line and the t line, and νd_3n_i represents an Abbe number for the d line of the negative lens for which the value of PCt_3n_i was calculated. . The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expressions.
(12) 0.2 ≦ | X2 / f2 | ≦ 0.9
However, X2 represents the amount of movement of the second lens group during zooming from the wide-angle end to the telephoto end. The zoom lens according to any one of claims 1 to 8, which satisfies the following conditional expression.
(13) 1.1 ≦ f23t / ft ≦ 2.8
Here, f23t is a combined focal length of the second lens group and the third lens group in the infinity object focused state at the telephoto end, and ft is a focal length of the entire lens system in the infinity object focused state at the telephoto end. Show. The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expressions.
(14) 3.2 ≦ | f3 / f2 | ≦ 80 An image pickup apparatus comprising: the zoom lens according to any one of claims 1 to 10; and a solid-state image pickup element that converts an optical image formed by the zoom lens into an electrical signal.

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