JP2017142468A - Zoom lens and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a downsized zoom lens that has chromatic aberrations excellently corrected with respect to light of a broad wavelength region from a visible light region to a near infrared region, and has high resolution.SOLUTION: A zoom lens is configured to have: a first lens group Gwith positive refractive power; a second lens group Gwith negative refractive power; a third lens group Gwith the positive refractive power; a fourth lens group Gwith the positive refractive power; and a fifth lens group Garranged in order from an object side, in which the third lens group Gis composed of, in order from the object side, : a 3a lens group Gcomposed of a positive lens L; and a 3b lens group Gcomposed of a positive les Land negative lens L. Then, a prescribed condition is satisfied to thereby obtain high resolution.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a zoom lens and an imaging apparatus on which a solid-state imaging device such as a CCD or a CMOS is mounted, and more particularly to a zoom lens suitable for a surveillance camera.

  In recent years, solid-state imaging devices such as CCD and COMS have been increased in the number of pixels, and solid-state imaging devices having 3 million pixels or more have become widespread. Along with this, the imaging lens is also required to have a high resolution that can cope with such a solid-state imaging device. Furthermore, in the case of an imaging lens used for a surveillance camera, the F-number is small to enable shooting in a low illumination environment, and the near infrared wavelength to enable shooting with near infrared light at night. It is necessary that the chromatic aberration is well corrected up to the region. In addition, with the widespread use of small surveillance dome cameras, the demand for a size that can be stored in a small dome has also increased in recent years.

  Conventionally, as a zoom lens capable of simplifying the structure of the mechanical mechanism and reducing the size of the entire lens system including the mechanical mechanism, a first lens having a positive refractive power in order from the object side. A group, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group, Various zoom lenses have been proposed in which the first lens group and the third lens group are fixed at the time of zooming, and zooming is performed by relatively changing the distance between the lens groups. Among them, a zoom lens having a resolving power that is compatible with an image sensor having a small F number and a relatively high pixel is known (for example, see Patent Document 1).

JP 2014-56055 A

  The zoom lens described in Patent Document 1 is a zoom lens having a zoom ratio of about 3.3 and an F number at the wide angle end of about 1.4. However, this zoom lens has insufficient correction of axial chromatic aberration with respect to light in the near-infrared region, and therefore, when photographing with near-infrared light at night, the resolving power that can accommodate a high-pixel image sensor is insufficient. doing.

  In order to solve the above-described problems caused by the conventional technology, the present invention is a compact zoom lens having a high resolving power in which chromatic aberration is well corrected for light in a wide wavelength range from the visible light region to the near infrared region. The purpose is to provide. It is another object of the present invention to provide a high-performance imaging device having high resolving power for light in a wide wavelength range from the visible light range to the near infrared range.

In order to solve the above-described problems and achieve the object, a zoom lens according to the present invention includes a first lens group having a positive refractive power and a second lens having a negative refractive power, which are sequentially arranged from the object side. And a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group, and fixing the first lens group and the third lens group In the zoom lens that performs zooming from the wide-angle end to the telephoto end by relatively changing the interval on the optical axis of each lens group, the third lens group is arranged in order from the object side. The 3a lens group is composed of a 3b lens group, the 3a lens group is composed of one positive lens, and the 3b lens group is composed of at least one positive lens and at least one lens. A negative lens, and Characterized in that it satisfies the matter equation.
(1) 0.7 ≦ f3a / f3 ≦ 1.3
(2) 68 ≦ νd — 3a
Here, f3a represents the focal length of the 3a lens group, f3 represents the focal length of the third lens group, and νd_3a represents the Abbe number with respect to the d-line of the positive lens constituting the 3a lens group.

  According to the present invention, it is possible to provide a small zoom lens having a high resolving power in which chromatic aberration is well corrected for light in a wide wavelength range from the visible light range to the near infrared range.

  Furthermore, in the zoom lens according to the present invention, in the above invention, of the negative lenses included in the third lens group, the negative lens disposed closest to the object side has a shape with a concave surface facing the image side. Features.

  According to the present invention, the ability to correct axial chromatic aberration and lateral chromatic aberration of the lens system can be further improved.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(3) 63 ≦ νd — 3 bp
Here, νd — 3bp indicates the Abbe number with respect to the d-line of the positive lens arranged closest to the object side among the positive lenses included in the third lens group.

  According to the present invention, axial chromatic aberration generated with respect to light in a wide wavelength range from the visible range to the near infrared range can be corrected more favorably.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(4) 2.7 ≦ f1 / fw ≦ 6.2
Here, f1 represents the focal length of the first lens group, and fw represents the focal length of the entire lens system at the wide angle end.

  According to the present invention, it is possible to improve the resolving power of the lens system and to promote downsizing of the entire lens system by setting the refractive power of the first lens group within an appropriate range.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(5) 1.6 ≦ f3 / fw ≦ 4.1
Here, fw represents the focal length of the entire lens system at the wide angle end.

  According to the present invention, the refractive power of the third lens group can be set within an appropriate range to improve the resolving power of the lens system and to promote downsizing of the entire lens system.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the fourth lens group includes two positive lenses and satisfies the following conditional expression.
(6) 63 ≦ νd — 4p
Here, νd — 4p represents the Abbe number with respect to the d line of the positive lens disposed closest to the object side among the positive lenses included in the fourth lens group.

  According to the present invention, it is possible to satisfactorily correct axial chromatic aberration, spherical aberration, and coma. In particular, it is possible to satisfactorily correct axial chromatic aberration that occurs with respect to light in a wide wavelength range from the visible range to the near infrared range.

  An image pickup apparatus according to the present invention includes the zoom lens according to the present invention, and a solid-state image sensor that converts an optical image formed by the zoom lens into an electrical signal.

  ADVANTAGE OF THE INVENTION According to this invention, the high performance imaging device provided with high resolving power with respect to the light of the wide wavelength range from visible light region to a near infrared region can be provided.

  According to the present invention, there is an effect that it is possible to provide a small zoom lens having a high resolving power for light in a wide wavelength range from the visible light range to the near infrared range.

  Furthermore, according to the present invention, there is an effect that it is possible to provide a high-performance imaging device having a high resolving power with respect to light in a wide wavelength range from the visible light range to the near infrared range.

FIG. 3 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to Example 1; FIG. 3 is a diagram illustrating all aberrations of the zoom lens according to Example 1; FIG. 6 is a cross-sectional view along the optical axis showing the configuration of a zoom lens according to Example 2; FIG. 10 is a diagram illustrating all aberrations of the zoom lens according to Example 2; FIG. 6 is a cross-sectional view along the optical axis showing the configuration of a zoom lens according to Example 3; FIG. 10 is a diagram illustrating all aberrations of the zoom lens according to Example 3; FIG. 6 is a cross-sectional view along the optical axis showing the configuration of a zoom lens according to Example 4; FIG. 10 is a diagram illustrating all aberrations of the zoom lens according to Example 4; FIG. 10 is a cross-sectional view along the optical axis showing the configuration of a zoom lens according to Example 5; FIG. 10 is a diagram illustrating all aberrations of the zoom lens according to Example 5; FIG. 10 is a cross-sectional view along the optical axis showing the configuration of a zoom lens according to Example 6; FIG. 10 is a diagram illustrating all aberrations of the zoom lens according to Example 6; 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 imaging apparatus according to the present invention will be described in detail.

  An object of the present invention is to provide a small zoom lens having a high resolving power in which chromatic aberration is well corrected for light in a wide wavelength range from the visible light region to the near infrared region. Therefore, in order to achieve this object, various conditions as shown below are set in the present invention.

  The zoom lens according to the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side. And a fourth lens group having a positive refractive power and a fifth lens group. Then, zooming from the wide-angle end to the telephoto end is performed by relatively changing the interval on the optical axis of each lens group while fixing the first lens group and the third lens group.

  When zooming from the wide-angle end to the telephoto end, an increase in the number of lens groups that move along the optical axis increases the degree of freedom in design, which is advantageous in terms of aberration correction and shortening the overall length of the lens system. The structure of the mechanical mechanism that controls zooming is complicated and large, and it is difficult to downsize the entire lens system including the mechanical mechanism. In addition, when the mechanical mechanism becomes complicated, the relative eccentricity of each lens group tends to increase during manufacturing, which causes a decrease in resolution. Therefore, in the zoom lens according to the present invention, in order to realize a zoom lens having a small size and a high resolving power, as described above, the lens group that moves during zooming from the wide-angle end to the telephoto end is minimized.

  When zooming from the wide-angle end to the telephoto end, a mechanical mechanism that controls zooming is achieved by fixing the largest and heaviest first lens group among all lens groups to the image plane. Further simplification makes it easy to reduce the size of the entire lens system including the mechanical mechanism, and it is easy to ensure the strength of the lens barrel.

  The first lens group is preferably configured by arranging a negative lens, a positive lens, and a positive lens in order from the object side. In particular, by configuring the first lens group, which is the largest among all the lens groups, with three lenses, it is possible to contribute to shortening the overall length of the lens system without reducing the resolving power.

  By disposing the negative lens closest to the object side in the first lens group, it is possible to satisfactorily correct axial chromatic aberration, spherical aberration, and coma at the telephoto end. In addition, since the first lens group includes two positive lenses, the positive refracting power can be shared by the two lenses, so that axial chromatic aberration on each surface of the two positive lenses, Generation of spherical aberration and coma aberration can be suppressed. In particular, axial chromatic aberration, spherical aberration, and coma at the telephoto end can be corrected well. In addition, if a cemented lens that is arranged on the object side in the first lens group and eliminates the air gap by a negative lens and a positive lens is formed, it is possible to suppress performance degradation due to errors in manufacturing such as decentration, It can also contribute to the miniaturization of the lens system.

  The second lens group is preferably configured by arranging a negative lens, a negative lens, and a positive lens in order from the object side. By constituting the second lens group with three lenses, it is possible to contribute to shortening the overall length of the lens system without reducing the resolving power.

  By disposing a positive lens in the second lens group, chromatic aberration can be corrected in the second lens group, and axial chromatic aberration and lateral chromatic aberration can be corrected well over the entire zooming range of the lens system. It becomes possible. In addition, since the second lens group includes two negative lenses, negative refracting power can be shared by the two lenses, so that axial chromatic aberration on each surface of the two negative lenses, Generation of spherical aberration, coma aberration, etc. can be suppressed. As a result, axial chromatic aberration, spherical aberration, coma and the like can be corrected well. In addition, if a cemented lens that eliminates the air gap is formed by a negative lens and a positive lens disposed on the image plane side in the second lens group, it is possible to suppress performance deterioration due to errors in manufacturing such as decentration. It can also contribute to downsizing of the lens system.

  Since the third lens group has a large influence on the resolution performance, an increase in the amount of decentering during manufacturing may cause a significant decrease in resolution. Therefore, by fixing the third lens unit to the image plane during zooming from the wide-angle end to the telephoto end, the mechanical mechanism can be simplified and the amount of eccentricity during manufacturing can be suppressed. become. As a result, a decrease in resolution can be prevented. Further, since the mechanical mechanism can be simplified, it is possible to reduce the size of the entire lens system including the mechanical mechanism.

  The fourth lens group has a function of further converging the light beam converged by the third lens group. Contributing to improving the resolving power by suppressing the occurrence of spherical aberration, coma aberration, and axial chromatic aberration in the third lens group by having the fourth lens group bear the convergence effect together with the third lens group. Yes.

  The fourth lens group is preferably configured by arranging a positive lens, a positive lens, and a negative lens in order from the object side. By configuring the fourth lens group with three lenses, it is possible to contribute to shortening the overall length of the lens system without reducing the resolving power.

  In particular, since the fourth lens group includes two positive lenses, the positive refractive power of the fourth lens group can be shared by the two positive lenses, and each surface of the two positive lenses. It is possible to suppress the occurrence of longitudinal chromatic aberration, spherical aberration, and coma aberration. As a result, axial chromatic aberration, spherical aberration, and coma can be corrected well. In addition, since the fourth lens group includes the negative lens, it is possible to satisfactorily correct axial chromatic aberration and lateral chromatic aberration, and to further improve the resolution. In particular, if a cemented lens that is disposed on the image plane side in the fourth lens group and eliminates the air gap is formed by a positive lens and a negative lens, it is possible to suppress performance deterioration due to errors in manufacturing such as decentration. It can also contribute to downsizing of the lens system.

  The fifth lens group is preferably configured by arranging one negative lens and one positive lens. By arranging the fifth lens group on the image side of the fourth lens group, astigmatism can be corrected well, and high resolution can be maintained up to the periphery of the screen.

  In the zoom lens according to the present invention, the third lens group has a function of converging the light beam diverged by the second lens group and guiding it to the fourth lens group following the image side. In the third lens group, since the light beam diverged by the second lens group passes, the light ray height at the wide-angle end is the highest. As a result, axial chromatic aberration, spherical aberration, and coma are likely to occur particularly at the wide angle end. Therefore, it is necessary to satisfactorily correct axial chromatic aberration, spherical aberration, and coma at the wide-angle end, and the lens configuration in the third lens group is particularly important.

  Therefore, in the zoom lens according to the present invention, it is preferable that the third lens group includes a third lens group having positive refractive power and a third lens group arranged in order from the object side. By doing so, the light beam diverged by the second lens group is quickly converged by the 3a lens group, the height of the light beam passing through the 3b lens group following the image side is lowered, and the lens of the 3b lens group This contributes to suppressing the occurrence of axial chromatic aberration, spherical aberration, and coma on each surface. As a result, it is possible to satisfactorily correct axial chromatic aberration, spherical aberration, and coma.

  The 3a lens group is preferably composed of one positive lens. By doing in this way, it becomes possible to shorten a lens system full length, and can contribute to size reduction of a lens whole system. The positive lens is arranged on the most object side in the third lens group. At this time, since the light beam diverged by the second lens group passes through the positive lens, the height of the light beam is increased in the positive lens, and spherical aberration and coma are easily generated. Therefore, it is preferable to form an aspheric surface on at least one surface of the positive lens. By doing in this way, it is possible to satisfactorily correct spherical aberration and coma aberration that become noticeable in the entire zoom range as the F number becomes smaller. By doing so, it is possible to realize a zoom lens that is bright and has high resolving power.

  In addition, it is preferable that the 3b lens group includes at least one positive lens and at least one negative lens. Since the 3b lens group has at least one positive lens, the positive refractive power in the third lens group can be shared with the 3a lens group, so that axial chromatic aberration on each surface of the lens of the 3a lens group In addition, the occurrence of spherical aberration and coma aberration can be suppressed. As a result, axial chromatic aberration, spherical aberration, and coma can be corrected satisfactorily, so that the resolving power of the lens system can be improved. In addition, since the third lens group includes at least one negative lens, it is possible to satisfactorily correct axial chromatic aberration and lateral chromatic aberration, and to further improve the resolving power of the lens system. In particular, it is possible to satisfactorily correct axial chromatic aberration that occurs with respect to light in the near infrared region at the wide-angle end.

  In addition, if the 3b lens group includes at least one positive lens and one negative lens, the above-described effects can be sufficiently obtained. If the third lens group is composed of two lenses, it is possible to promote downsizing of the lens system. Further, when a cemented lens is formed by eliminating the air gap with these two lenses, it is possible to suppress performance deterioration due to manufacturing errors such as decentration and contribute to further downsizing of the lens system. .

  By the way, when the 3b lens group is configured by two lenses, if the 3b lens group is configured by arranging a negative lens and a positive lens in order from the object side, the following inconvenience occurs. That is, after the light beam diverged by the second lens group is converged by the 3a lens group, the light beam jumps up again in the negative lens disposed on the object side, and the light beam of the positive lens disposed on the image side. High becomes high. As a result, spherical aberration, axial chromatic aberration, and coma are significantly generated in the positive lens disposed on the image side, and it may be difficult to correct spherical aberration, axial chromatic aberration, and coma. Therefore, it is preferable that the third lens group is configured by arranging a positive lens and a negative lens in order from the object side.

In addition, in the zoom lens according to the present invention, on the premise of the above configuration, the focal length of the 3a lens group is f3a, the focal length of the third lens group is f3, and the d-line of the positive lens constituting the 3a lens group is When the Abbe number is νd_3a, it is preferable that the following conditional expression is satisfied.
(1) 0.7 ≦ f3a / f3 ≦ 1.3
(2) 68 ≦ νd — 3a

  Conditional expression (1) is an expression that defines the focal length of the third lens group with respect to the focal length of the third lens group. When the conditional expression (1) is satisfied, the refractive power of the 3a lens group in the third lens group can be set in an appropriate range, and the resolving power of the lens system can be improved.

  If the lower limit of conditional expression (1) is not reached, the refractive power of the 3a lens group becomes too strong, and the occurrence of spherical aberration, axial chromatic aberration, and coma aberration in the 3a lens group becomes remarkable. As a result, it becomes difficult to satisfactorily correct spherical aberration, axial chromatic aberration, and coma at the wide-angle end, which causes a reduction in the resolving power of the lens system. In particular, it is difficult to satisfactorily correct axial chromatic aberration that occurs with respect to light in the near infrared region, and high resolution for light in the near infrared region cannot be ensured.

  On the other hand, if the upper limit in conditional expression (1) is exceeded, the refractive power of the 3a lens group becomes too weak, and the light beam diverged in the 2nd lens group cannot be sufficiently converged by the 3a lens group. The height of the light beam passing through the lens group becomes high, and the occurrence of axial chromatic aberration, spherical aberration, and coma aberration on each lens surface of the 3b lens group becomes remarkable. As a result, it is difficult to satisfactorily correct axial chromatic aberration, spherical aberration, and coma with a small number of lenses. If the number of lenses constituting the third lens group is increased, the aberration correction capability can be ensured, but the total length of the third lens group becomes long, and there is a problem that it is difficult to downsize the entire lens system.

In addition, the said conditional expression (1) can anticipate a more preferable effect, if the range shown next is satisfied.
(1a) 0.8 ≦ f3a / f3 ≦ 1.2

  Conditional expression (2) defines the Abbe number for the d-line of the positive lens constituting the 3a lens group. By satisfying conditional expression (2), it is possible to satisfactorily correct axial chromatic aberration generated for light in a wide wavelength range from the visible range to the near infrared range. In the third lens group through which the luminous flux diverged by the second lens group passes, since the ray height at the wide-angle end is highest in the positive lens of the 3a lens group located closest to the object side, axial chromatic aberration is particularly generated. It becomes easy to do. Therefore, in order to satisfactorily correct the axial chromatic aberration, it is particularly important to appropriately select the glass material of the positive lens in the 3a lens group.

  If the lower limit of conditional expression (2) is not reached, the occurrence of longitudinal chromatic aberration in the 3a lens group becomes significant. As a result, the correction of the axial chromatic aberration in the entire third lens group is insufficient, and it becomes difficult to satisfactorily correct the axial chromatic aberration generated at the wide angle end, which causes a reduction in the resolving power of the lens system. In particular, it is difficult to satisfactorily correct axial chromatic aberration that occurs with respect to light in the near infrared region, and high resolution for light in the near infrared region cannot be ensured.

In addition, the said conditional expression (2) can anticipate a more preferable effect, if the range shown next is satisfied.
(2a) 74 ≦ νd — 3a

  Furthermore, in the zoom lens according to the present invention, among the negative lenses included in the 3b lens group, it is preferable that the negative lens arranged closest to the object side has a concave surface facing the image side. In this way, the ability to correct axial chromatic aberration and lateral chromatic aberration can be further improved. As a result, it is possible to further improve the resolving power of the lens system.

Furthermore, in the zoom lens according to the present invention, when the Abbe number with respect to the d-line of the positive lens disposed closest to the object among the positive lenses included in the 3b lens group is νd_3 bp, the following conditional expression is satisfied. It is preferable to do.
(3) 63 ≦ νd — 3 bp

  Conditional expression (3) is an expression that prescribes the Abbe number with respect to the d-line of the positive lens arranged closest to the object side among the positive lenses included in the third lens group. By satisfying conditional expression (3), axial chromatic aberration generated for light in a wide wavelength range from the visible range to the near infrared range can be corrected more satisfactorily.

  If the lower limit of conditional expression (3) is not reached, the occurrence of longitudinal chromatic aberration in the 3b lens group becomes significant. As a result, the correction of the axial chromatic aberration in the third lens group is insufficient, and it is difficult to satisfactorily correct the axial chromatic aberration generated at the wide angle end, which causes a reduction in the resolving power of the lens system. In particular, it is difficult to satisfactorily correct axial chromatic aberration that occurs with respect to light in the near infrared region, and high resolution for light in the near infrared region cannot be ensured.

In addition, if the said conditional expression (3) satisfies the range shown next, a more preferable effect can be anticipated.
(3a) 68 ≦ νd — 3 bp

Furthermore, in the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied, where f1 is the focal length of the first lens group and fw is the focal length of the entire lens system at the wide angle end.
(4) 2.7 ≦ f1 / fw ≦ 6.2

  Conditional expression (4) defines the focal length of the first lens group with respect to the focal length of the entire lens system at the wide angle end. By satisfying conditional expression (4), it is possible to set the refractive power of the first lens group within an appropriate range, improve the resolving power of the lens system, and promote downsizing of the entire lens system.

  If the lower limit of conditional expression (4) is surpassed, the refractive power of the first lens group becomes too strong, and the occurrence of spherical aberration, axial chromatic aberration, and coma aberration on each surface of the lens of the first lens group is remarkable at the telephoto end. become. As a result, it becomes difficult to correct spherical aberration, axial chromatic aberration, and coma at the telephoto end, which causes a reduction in the resolving power of the lens system.

  On the other hand, if the upper limit of conditional expression (4) is exceeded, the refractive power of the first lens group becomes too weak and correction of various aberrations becomes easy, but the total length of the lens system becomes long and the entire lens system becomes compact. It becomes difficult.

In addition, if the said conditional expression (4) satisfies the range shown next, a more preferable effect can be anticipated.
(4a) 3.1 ≦ f1 / fw ≦ 5.4

Further, when the conditional expression (4a) satisfies the following range, a more preferable effect can be expected.
(4b) 3.5 ≦ f1 / fw ≦ 5.0

Furthermore, in the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied when the focal length of the third lens unit is f3 and the focal length of the entire lens system at the wide angle end is fw.
(5) 1.6 ≦ f3 / fw ≦ 4.1

  Conditional expression (5) defines the focal length of the third lens group with respect to the focal length of the entire lens system at the wide angle end. By satisfying conditional expression (5), it is possible to set the refractive power of the third lens group in an appropriate range, improve the resolving power of the lens system, and promote downsizing of the entire lens system.

  If the lower limit of conditional expression (5) is not reached, the refractive power of the third lens group becomes too strong, and the occurrence of spherical aberration, axial chromatic aberration, and coma aberration on each lens surface constituting the third lens group becomes remarkable. Become. As a result, it becomes difficult to correct spherical aberration, axial chromatic aberration, and coma at the wide-angle end, which causes a reduction in the resolving power of the lens system.

  On the other hand, if the upper limit of conditional expression (5) is exceeded, the refractive power of the third lens group becomes too weak and correction of various aberrations is facilitated, but the total length of the lens system becomes long and the entire lens system becomes compact. It becomes difficult.

In addition, the said conditional expression (5) can anticipate a more preferable effect, if the range shown next is satisfied.
(5a) 1.9 ≦ f3 / fw ≦ 3.8

Further, when the conditional expression (5a) satisfies the following range, a more preferable effect can be expected.
(5b) 2.1 ≦ f3 / fw ≦ 3.5

  Furthermore, in the zoom lens according to the present invention, it is preferable that the fourth lens group includes two positive lenses. Since the fourth lens group has two positive lenses, the positive refractive power in the fourth lens group can be shared by the two lenses, and axial chromatic aberration on each surface of the lens constituting the fourth lens group. In addition, the occurrence of spherical aberration and coma aberration can be suppressed. As a result, axial chromatic aberration, spherical aberration, and coma aberration can be corrected well, and the resolving power of the lens system can be further improved.

In addition, the zoom lens according to the present invention is arranged on the most object side among the positive lenses included in the fourth lens group on the assumption that the fourth lens group includes two positive lenses. When the Abbe number for the d-line of the positive lens is νd — 4p, it is preferable that the following conditional expression is satisfied.
(6) 63 ≦ νd — 4p

  Conditional expression (6) is an expression that prescribes the Abbe number with respect to the d-line of the positive lens arranged closest to the object side among the positive lenses included in the fourth lens group. By satisfying conditional expression (6), it is possible to satisfactorily correct axial chromatic aberration generated for light in a wide wavelength range from the visible range to the near infrared range. The fourth lens group has a function of further converging the light beam converged by the third lens group. For this reason, among the positive lenses constituting the fourth lens group, the light beam passes through the highest position of the positive lens disposed closest to the object side, and axial chromatic aberration is likely to occur. Therefore, it is important to appropriately select a glass material for forming a positive lens disposed closest to the object side among the positive lenses constituting the fourth lens group.

  If the lower limit of conditional expression (6) is not reached, the occurrence of longitudinal chromatic aberration and lateral chromatic aberration in the fourth lens group becomes significant. As a result, the resolving power of the lens system is reduced. In particular, it is difficult to satisfactorily correct axial chromatic aberration that occurs for near-infrared light at the wide-angle end.

In addition, when the conditional expression (6) satisfies the following range, a more preferable effect can be expected.
(6a) 68 ≦ νd — 4p

  As described above, according to the present invention, by providing the above-described configuration, it has a high resolution capable of dealing with a solid-state imaging device with high pixels and high sensitivity, particularly from the visible light region to the near infrared region. It is possible to realize a small zoom lens capable of satisfactorily correcting various aberrations generated for light having a wide range of wavelengths over the entire zooming range.

  The zoom lens according to the present invention having such features is suitable for an imaging apparatus that requires high resolving power not only for the visible light region but also for light in a wide wavelength range up to the near infrared region.

  Furthermore, an object of the present invention is to provide a high-performance imaging device having a high resolving power with respect to light in a wide wavelength range from the visible light range to the near infrared range. In order to achieve this object, an imaging apparatus may be configured by including a zoom lens having the above-described configuration and a solid-state imaging device that converts an optical image formed by the zoom lens into an electrical signal. By doing in this way, it is possible to realize a high-performance imaging device having a high resolving power for light in a wide wavelength range up to the near infrared range as well as the visible light range.

  Embodiments of the zoom lens according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by the following examples.

FIG. 1 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to the first embodiment. This figure shows the state of the wide-angle end of the lens system. The zoom lens includes a first lens group G ₁₁ having a positive refractive power, a second lens group G ₁₂ having a negative refractive power, and a third lens group having a positive refractive power in order from an object side (not shown). G ₁₃ , a fourth lens group G ₁₄ having a positive refractive power, and a fifth lens group G ₁₅ having a positive refractive power are arranged. A second lens group G ₁₂ between the third lens group G _13, an aperture stop STOP is positioned to define the predetermined diameter. A cover glass CG is disposed between the fifth lens group G ₁₅ and the image plane IMG.

The first lens group G ₁₁ includes, in order from the object side, a negative lens L _111, a positive lens L _112, a positive lens L _113, is formed are disposed. The negative lens L ₁₁₁ and the positive lens L ₁₁₂ are cemented.

Second lens group G ₁₂ configured in order from the object side, a negative lens L _121, a negative lens L _122, a positive lens L _123, it is the arrangement. The negative lens L ₁₂₂ and the positive lens L ₁₂₃ are cemented.

The third lens group G ₁₃ includes a third a lens group G _13a having a positive refractive power and a third b lens group G _13b arranged in this order from the object side.

The third-a lens group G _13a is composed of a positive lens L ₁₃₁ . Aspherical surfaces are formed on both surfaces of the positive lens _L131 . The third-b lens group G _13b is configured by arranging a positive lens L ₁₃₂ and a negative lens L _{133 in} order from the object side. The negative lens L ₁₃₃ is disposed with the concave surface facing the image plane IMG side. The positive lens L ₁₃₂ and the negative lens L ₁₃₃ are cemented.

The fourth lens group G ₁₄ is constituted in order from the object side, a positive lens L _141, a positive lens L _142, a negative lens L _143, been arranged. Aspherical surfaces are formed on both surfaces of the positive lens _L141 . The positive lens L ₁₄₂ and the negative lens L ₁₄₃ are cemented.

The fifth lens group G ₁₅ includes a negative lens L ₁₅₁ and a positive lens L ₁₅₂ arranged in order from the object side.

In this zoom lens, the second lens group G ₁₂ and the fourth lens group G ₁₁ , the aperture stop STOP, the third lens group G ₁₃ , and the fifth lens group G ₁₅ are fixed to the image plane IMG. by moving the lens group G ₁₄ along the optical axis, and performs zooming from the wide-angle end to the telephoto end. More specifically, the second lens group G ₁₂ by moving from the object side to the image plane IMG side performs zooming to the telephoto end from the wide-angle end, along the fourth lens group G ₁₄ to the optical axis It is moved to correct the focus position accompanying the zooming and focus.

  Various numerical data related to the zoom lens according to Example 1 will be described below.

(Surface data)
r ₁ = 67.918
d ₁ = 1.00 nd ₁ = 1.92286 νd ₁ = 18.90
r ₂ = 42.984
d ₂ = 3.65 nd ₂ = 1.49700 νd ₂ = 81.61
r ₃ = -68.509
d ₃ = 0.10
r ₄ = 25.447
d ₄ = 2.46 nd ₃ = 1.59349 νd ₃ = 67.00
r ₅ = 56.018
d ₅ = D (5) (variable)
r ₆ = -63.630
d ₆ = 0.60 nd ₄ = 1.80420 νd ₄ = 46.50
r ₇ = 16.343
d ₇ = 2.11
r ₈ = -17.805
d ₈ = 0.78 nd ₅ = 1.51680 νd ₅ = 64.20
r ₉ = 19.243
d ₉ = 1.84 nd ₆ = 1.95906 νd ₆ = 17.47
r ₁₀ = 66.934
d ₁₀ = D (10) (variable)
r ₁₁ = ∞ (aperture stop)
d ₁₁ = 0.54
r ₁₂ = 21.358 (aspherical surface)
d ₁₂ = 3.16 nd ₇ = 1.55332 νd ₇ = 71.68
r ₁₃ = -45.940 (aspherical surface)
d ₁₃ = 0.10
r ₁₄ = 13.062
d ₁₄ = 3.10 nd ₈ = 1.43700 νd ₈ = 95.10
r ₁₅ = -65.058
d ₁₅ = 0.80 nd ₉ = 1.73800 νd ₉ = 32.26
r ₁₆ = 24.497
d ₁₆ = D (16) (variable)
r ₁₇ = 27.199 (aspherical surface)
d ₁₇ = 2.53 nd ₁₀ = 1.49710 νd ₁₀ = 81.56
r ₁₈ = -20.210 (aspherical surface)
d ₁₈ = 0.10
r ₁₉ = 8.805
d ₁₉ = 2.00 nd ₁₁ = 1.43700 νd ₁₁ = 95.10
r ₂₀ = 13.243
d ₂₀ = 1.56 nd ₁₂ = 1.72047 νd ₁₂ = 34.71
r ₂₁ = 7.621
d ₂₁ = D (21) (variable)
r ₂₂ = 26.820
d ₂₂ = 0.56 nd ₁₃ = 1.72047 νd ₁₃ = 34.71
r ₂₃ = 8.663
d ₂₃ = 0.70
r ₂₄ = 18.494
d ₂₄ = 1.59 nd ₁₄ = 1.91082 νd ₁₄ = 35.25
r ₂₅ = -115.233
d ₂₅ = 6.29
r ₂₆ = ∞
d ₂₆ = 1.50 nd ₁₅ = 1.51633 νd ₁₅ = 64.14
r ₂₇ = ∞
d ₂₇ = 0.50
r ₂₈ = ∞ (image plane)

Cone coefficient (ε) and aspheric coefficient (A, B, C, D, E)
(Twelfth surface)
ε = 1.000,
A = 0, B = 3.44901 × 10 ⁻⁵ , C = 5.338956 × 10 ⁻⁷ ,
D = -5.26594 × 10 ^-9 , E = 2.88724 × 10 ^-10
(13th page)
ε = 1.000,
A = 0, B = 8.36982 × 10 ⁻⁵ , C = 5.87291 × 10 ⁻⁷ ,
D = -6.59230 × 10 ^-9 , E = 3.72006 × 10 ^-10
(Seventeenth surface)
ε = 1.000,
A = 0, B = -7.69342 × 10 ⁻⁵ , C = 1.29819 × 10 ⁻⁶ ,
D = -8.12607 × 10 ^-8 , E = 1.80590 × 10 ^-9
(18th page)
ε = 1.000,
A = 0, B = 1.95080 × 10 ⁻⁵ , C = 1.22824 × 10 ⁻⁶ ,
D = -7.88723 × 10 ^-8 , E = 1.86897 × 10 ^-9

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 10.09 19.79 38.83
F number 1.69 1.81 2.15
Half angle of view (ω) 20.4 10.1 5.1
D (5) 1.10 10.20 18.23
D (10) 19.41 10.31 2.28
D (16) 4.93 2.72 2.86
D (21) 1.82 4.03 3.89

(Zoom lens group data)
Group Start surface Focal length 1 1 41.81
2 6 -11.67
3 12 23.72
4 17 26.42
5 22 299.67

(Numerical values related to conditional expression (1))
f3a (focal length of the 3a lens group G _13a) = 26.80
f3 (the focal length of the third lens group G ₁₃₎ = 23.72
f3a / f3 = 1.13

(Numerical value for conditional expression (2))
νd — 3a (the Abbe number of the positive lens L ₁₃₁ with respect to the d line) = 71.68

(Numerical values related to conditional expression (3))
νd — 3 bp (Abbe number of the positive lens L ₁₃₂ with respect to the d line) = 95.10

(Numerical values related to conditional expression (4))
f1 (the focal length of the first lens group G ₁₁₎ = 41.81
fw (focal length of the entire lens system at the wide angle end) = 10.09
f1 / fw = 4.14

(Numerical values related to conditional expression (5))
f3 (the focal length of the third lens group G ₁₃₎ = 23.72
fw (focal length of the entire lens system at the wide angle end) = 10.09
f3 / fw = 2.35

(Numerical values related to conditional expression (6))
νd — 4p (Abbe number with respect to the d-line of the positive lens L ₁₄₁ ) = 81.56

  FIG. 2 is a diagram illustrating various aberrations of the zoom lens according to the first example. In the spherical aberration diagram, FNO represents the F number, the solid line is the d line (587.6 nm), the short broken line is the g line (435.8 nm), the long broken line is the C line (656.3 nm), and the alternate long and short dash line is the near infrared The characteristics of light rays (850.0 nm, indicated by IR in the figure) are shown. In the astigmatism diagram, ω represents a half angle of view and indicates the d-line characteristic. In the graph showing astigmatism, the solid line indicates the characteristics of the sagittal image plane (indicated by S in the figure), and the broken line indicates the characteristics of the meridional image plane (indicated by M in the figure). In the distortion diagram, ω represents a half angle of view and indicates the d-line characteristic.

FIG. 3 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to the second embodiment. This figure shows the state of the wide-angle end of the lens system. In this zoom lens, in order from the object side (not shown), a first lens group G ₂₁ having a positive refractive power, a second lens group G ₂₂ having a negative refractive power, and a third lens group having a positive refractive power. G ₂₃ , a fourth lens group G ₂₄ having a positive refractive power, and a fifth lens group G ₂₅ having a negative refractive power are arranged. An aperture stop STOP that defines a predetermined aperture is disposed between the second lens group G ₂₂ and the third lens group G ₂₃ . A cover glass CG is disposed between the fifth lens group G ₂₅ and the image plane IMG.

The first lens group G ₂₁ includes a negative lens L ₂₁₁ , a positive lens L _212, and a positive lens L ₂₁₃ arranged in this order from the object side. The negative lens L ₂₁₁ and the positive lens L ₂₁₂ are cemented.

Second lens group G ₂₂ configured in order from the object side, a negative lens L _221, a negative lens L _222, a positive lens L _223, it is the arrangement. The negative lens L ₂₂₂ and the positive lens L ₂₂₃ are cemented.

The third lens group G ₂₃ includes a third a lens group G _23a having a positive refractive power and a third b lens group G _23b arranged in this order from the object side.

The third-a lens group G _23a is composed of a positive lens L ₂₃₁ . Aspherical surfaces are formed on both surfaces of the positive lens _L231 . The third-b lens group G _23b includes a positive lens L ₂₃₂ and a negative lens L ₂₃₃ arranged in this order from the object side. The negative lens L ₂₃₃ is arranged with the concave surface facing the image plane IMG side. The positive lens L ₂₃₂ and the negative lens L ₂₃₃ are cemented.

The fourth lens group G ₂₄ is constituted in order from the object side, a positive lens L _241, a positive lens L _242, a negative lens L _243, is the arrangement. Aspherical surfaces are formed on both surfaces of the positive lens _L241 . The positive lens L ₂₄₂ and the negative lens L ₂₄₃ are cemented.

The fifth lens group G ₂₅ includes a negative lens L ₂₅₁ and a positive lens L ₂₅₂ arranged in this order from the object side.

In this zoom lens, the second lens group G ₂₂ and the fourth lens group G ₂₁ , the aperture stop STOP, the third lens group G ₂₃ , and the fifth lens group G ₂₅ are fixed to the image plane IMG. by moving the lens group G ₂₄ along the optical axis, and performs zooming from the wide-angle end to the telephoto end. More specifically, by moving the second lens group G ₂₂ from the object side to the image plane IMG side, zooming from the wide-angle end to the telephoto end is performed, and the fourth lens group G ₂₄ is moved along the optical axis. It is moved to correct the focus position accompanying the zooming and focus.

  Various numerical data related to the zoom lens according to Example 2 will be described below.

(Surface data)
r ₁ = 72.390
d ₁ = 1.00 nd ₁ = 1.92286 νd ₁ = 20.88
r ₂ = 43.764
d ₂ = 3.40 nd ₂ = 1.49700 νd ₂ = 81.61
r ₃ = -74.686
d ₃ = 0.10
r ₄ = 30.407
d ₄ = 2.40 nd ₃ = 1.61800 νd ₃ = 63.40
r ₅ = 64.890
d ₅ = D (5) (variable)
r ₆ = -69.490
d ₆ = 0.60 nd ₄ = 1.78590 νd ₄ = 43.93
r ₇ = 18.301
d ₇ = 1.71
r ₈ = -19.128
d ₈ = 0.55 nd ₅ = 1.51680 νd ₅ = 64.20
r ₉ = 21.464
d ₉ = 1.71 nd ₆ = 1.95906 νd ₆ = 17.47
r ₁₀ = 87.183
d ₁₀ = D (10) (variable)
r ₁₁ = ∞ (aperture stop)
d ₁₁ = 0.42
r ₁₂ = 13.692 (aspherical surface)
d ₁₂ = 2.89 nd ₇ = 1.49710 νd ₇ = 81.56
r ₁₃ = -184.620 (aspherical surface)
d ₁₃ = 0.10
r ₁₄ = 14.999
d ₁₄ = 2.88 nd ₈ = 1.43700 νd ₈ = 95.10
r ₁₅ = -79.092
d ₁₅ = 0.88 nd ₉ = 1.74950 νd ₉ = 35.33
r ₁₆ = 18.101
d ₁₆ = D (16) (variable)
r ₁₇ = 17.875 (aspherical surface)
d ₁₇ = 2.60 nd ₁₀ = 1.49710 νd ₁₀ = 81.56
r ₁₈ = -17.615 (aspherical surface)
d ₁₈ = 0.10
r ₁₉ = 9.297
d ₁₉ = 2.14 nd ₁₁ = 1.43700 νd ₁₁ = 95.10
r ₂₀ = 10.549
d ₂₀ = 1.96 nd ₁₂ = 1.64769 νd ₁₂ = 33.84
r ₂₁ = 6.900
d ₂₁ = D (21) (variable)
r ₂₂ = 35.039
d ₂₂ = 0.45 nd ₁₃ = 1.83400 νd ₁₃ = 37.35
r ₂₃ = 9.793
d ₂₃ = 0.50
r ₂₄ = 18.673
d ₂₄ = 1.39 nd ₁₄ = 1.88100 νd ₁₄ = 40.14
r ₂₅ = -81.081
d ₂₅ = 6.28
r ₂₆ = ∞
d ₂₆ = 1.50 nd ₁₅ = 1.51633 νd ₁₅ = 64.14
r ₂₇ = ∞
d ₂₇ = 0.50
r ₂₈ = ∞ (image plane)

Cone coefficient (ε) and aspheric coefficient (A, B, C, D, E)
(Twelfth surface)
ε = 1.000,
A = 0, B = 2.36209 × 10 ⁻⁶ , C = 1.20099 × 10 ⁻⁶ ,
D = -4.38589 × 10 ⁻⁸ , E = 8.31154 × 10 ⁻¹⁰
(13th page)
ε = 1.000,
A = 0, B = 8.68784 × 10 ⁻⁵ , C = 1.14366 × 10 ⁻⁶ ,
D = -4.19602 × 10 ⁻⁸ , E = 9.13929 × 10 ⁻¹⁰
(Seventeenth surface)
ε = 1.000,
A = 0, B = -1.02251 × 10 ⁻⁴ , C = 1.03311 × 10 ⁻⁶ ,
D = -8.58837 x 10 ^-8 , E = 1.51734 x 10 ^-9
(18th page)
ε = 1.000,
A = 0, B = 3.80853 × 10 ⁻⁵ , C = 5.87307 × 10 ⁻⁷ ,
D = -6.83737 × 10 ⁻⁸ , E = 1.33941 × 10 ⁻⁹

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 10.09 19.79 38.83
F number 1.65 1.82 2.75
Half angle of view (ω) 20.4 10.1 5.1
D (5) 0.94 11.31 20.49
D (10) 21.61 11.25 2.06
D (16) 4.36 2.51 2.09
D (21) 1.85 3.69 4.12

(Zoom lens group data)
Group Start surface Focal length 1 1 48.29
2 6 -13.55
3 12 32.18
4 17 18.87
5 22 -774.04

(Numerical values related to conditional expression (1))
f3a (focal length of the 3a lens group G _23a) = 25.77
f3 (the focal length of the third lens group G ₂₃₎ = 32.18
f3a / f3 = 0.80

(Numerical value for conditional expression (2))
νd — 3a (Abbe number with respect to d line of positive lens L ₂₃₁ ) = 81.56

(Numerical values related to conditional expression (3))
νd — 3 bp (Abbe number with respect to d line of positive lens L ₂₃₂ ) = 95.10

(Numerical values related to conditional expression (4))
f1 (the focal length of the first lens group G ₂₁₎ = 48.29
fw (focal length of the entire lens system at the wide angle end) = 10.09
f1 / fw = 4.79

(Numerical values related to conditional expression (5))
f3 (the focal length of the third lens group G ₂₃₎ = 32.18
fw (focal length of the entire lens system at the wide angle end) = 10.09
f3 / fw = 3.19

(Numerical values related to conditional expression (6))
νd — 4p (Abbe number with respect to d line of positive lens L ₂₄₁ ) = 81.56

  FIG. 4 is a diagram illustrating various aberrations of the zoom lens according to the second example. In the spherical aberration diagram, FNO represents the F number, the solid line is the d line (587.6 nm), the short broken line is the g line (435.8 nm), the long broken line is the C line (656.3 nm), and the alternate long and short dash line is the near infrared The characteristics of light rays (850.0 nm, indicated by IR in the figure) are shown. In the astigmatism diagram, ω represents a half angle of view and indicates the d-line characteristic. In the graph showing astigmatism, the solid line indicates the characteristics of the sagittal image plane (indicated by S in the figure), and the broken line indicates the characteristics of the meridional image plane (indicated by M in the figure). In the distortion diagram, ω represents a half angle of view and indicates the d-line characteristic.

FIG. 5 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to the third embodiment. This figure shows the state of the wide-angle end of the lens system. The zoom lens includes a first lens group G ₃₁ having a positive refractive power, a second lens group G ₃₂ having a negative refractive power, and a third lens group having a positive refractive power in order from an object side (not shown). G ₃₃ , a fourth lens group G ₃₄ having a positive refractive power, and a fifth lens group G ₃₅ having a positive refractive power are arranged. An aperture stop STOP that defines a predetermined aperture is disposed between the second lens group G ₃₂ and the third lens group G ₃₃ . A cover glass CG is disposed between the fifth lens group G ₃₅ and the image plane IMG.

The first lens group G ₃₁ includes a negative lens L ₃₁₁ , a positive lens L _312, and a positive lens L ₃₁₃ arranged in order from the object side. The negative lens L ₃₁₁ and the positive lens L ₃₁₂ are cemented.

The second lens group G ₃₂ includes, in order from the object side, a negative lens L _321, a negative lens L _322, a positive lens L _323, is formed are disposed. The negative lens L ₃₂₂ and the positive lens L ₃₂₃ are cemented.

The third lens group G ₃₃ is configured by, in order from the object side, a third a lens group G _33a having a positive refractive power and a third b lens group G _33b .

The third-a lens group G _33a is composed of a positive lens L ₃₃₁ . Aspherical surfaces are formed on both surfaces of the positive lens _L331 . The third-b lens group G _33b includes a positive lens L ₃₃₂ and a negative lens L ₃₃₃ arranged in order from the object side. The negative lens L ₃₃₃ is disposed with the concave surface facing the image plane IMG side. The positive lens L ₃₃₂ and the negative lens L ₃₃₃ are cemented.

The fourth lens group G ₃₄ is constituted in order from the object side, a positive lens L _341, a positive lens L _342, a negative lens L _343, is the arrangement. Aspheric surfaces are formed on both surfaces of the positive lens L ₃₄₁ . The positive lens L ₃₄₂ and the negative lens L ₃₄₃ are cemented.

The fifth lens group G ₃₅ includes a negative lens L ₃₅₁ and a positive lens L ₃₅₂ arranged in this order from the object side.

In this zoom lens, the second lens group G ₃₂ and the fourth lens group G ₃₁ , the aperture stop STOP, the third lens group G ₃₃ , and the fifth lens group G ₃₅ are fixed to the image plane IMG. by moving the lens group G ₃₄ along the optical axis, and performs zooming from the wide-angle end to the telephoto end. More specifically, the second lens group G ₃₂ by moving from the object side to the image plane IMG side performs zooming to the telephoto end from the wide-angle end, along the fourth lens group G ₃₄ to the optical axis It is moved to correct the focus position accompanying the zooming and focus.

  Various numerical data relating to the zoom lens according to Example 3 will be described below.

(Surface data)
r ₁ = 71.157
d ₁ = 0.90 nd ₁ = 1.92286 νd ₁ = 18.90
r ₂ = 45.077
d ₂ = 3.50 nd ₂ = 1.49700 νd ₂ = 81.61
r ₃ = -65.956
d ₃ = 0.10
r ₄ = 23.400
d ₄ = 2.40 nd ₃ = 1.59282 νd ₃ = 68.62
r ₅ = 52.120
d ₅ = D (5) (variable)
r ₆ = -50.491
d ₆ = 0.60 nd ₄ = 1.80610 νd ₄ = 40.73
r ₇ = 14.257
d ₇ = 1.80
r ₈ = -16.978
d ₈ = 0.90 nd ₅ = 1.51680 νd ₅ = 64.20
r ₉ = 18.254
d ₉ = 1.66 nd ₆ = 2.00272 νd ₆ = 19.32
r ₁₀ = 96.372
d ₁₀ = D (10) (variable)
r ₁₁ = ∞ (aperture stop)
d ₁₁ = 0.30
r ₁₂ = 15.212 (aspherical surface)
d ₁₂ = 3.22 nd ₇ = 1.49710 νd ₇ = 81.56
r ₁₃ = -68.901 (aspherical surface)
d ₁₃ = 0.48
r ₁₄ = 15.379
d ₁₄ = 3.13 nd ₈ = 1.49700 νd ₈ = 81.61
r ₁₅ = −74.227
d ₁₅ = 0.62 nd ₉ = 1.74950 νd ₉ = 35.33
r ₁₆ = 19.753
d ₁₆ = D (16) (variable)
r ₁₇ = 21.493 (aspherical surface)
d ₁₇ = 3.21 nd ₁₀ = 1.49710 νd ₁₀ = 81.56
r ₁₈ = -23.403 (aspherical surface)
d ₁₈ = 0.10
r ₁₉ = 8.648
d ₁₉ = 1.82 nd ₁₁ = 1.43700 νd ₁₁ = 95.10
r ₂₀ = 14.063
d ₂₀ = 1.66 nd ₁₂ = 1.72047 νd ₁₂ = 34.71
r ₂₁ = 7.833
d ₂₁ = D (21) (variable)
r ₂₂ = 26.761
d ₂₂ = 0.55 nd ₁₃ = 1.72047 νd ₁₃ = 34.71
r ₂₃ = 9.922
d ₂₃ = 0.88
r ₂₄ = 11.936
d ₂₄ = 1.62 nd ₁₄ = 1.90043 νd ₁₄ = 37.37
r ₂₅ = 39.416
d ₂₅ = 6.28
r ₂₆ = ∞
d ₂₆ = 1.50 nd ₁₅ = 1.51633 νd ₁₅ = 64.14
r ₂₇ = ∞
d ₂₇ = 0.50
r ₂₈ = ∞ (image plane)

Cone coefficient (ε) and aspheric coefficient (A, B, C, D, E)
(Twelfth surface)
ε = 1.000,
A = 0, B = -4.95125 × 10 ⁻⁶ , C = 1.11061 × 10 ⁻⁶ ,
D = -2.20761 × 10 ⁻⁸ , E = 3.26282 × 10 ⁻¹⁰
(13th page)
ε = 1.000,
A = 0, B = 6.63946 × 10 ⁻⁵ , C = 1.32190 × 10 ⁻⁶ ,
D = -2.59879 × 10 ⁻⁸ , E = 3.75866 × 10 ⁻¹⁰
(Seventeenth surface)
ε = 1.000,
A = 0, B = 1.57052 × 10 ⁻⁵ , C = 5.23184 × 10 ⁻⁶ ,
D = -1.16508 × 10 ⁻⁷ , E = 3.04822 × 10 ⁻⁹
(18th page)
ε = 1.000,
A = 0, B = 1.16619 × 10 ⁻⁴ , C = 6.08996 × 10 ⁻⁶ ,
D = -1.66702 × 10 ⁻⁷ , E = 4.75303 × 10 ⁻⁹

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 10.09 19.79 38.83
F number 1.65 1.84 2.15
Half angle of view (ω) 20.8 10.3 5.2
D (5) 1.49 10.02 17.89
D (10) 18.90 10.37 2.49
D (16) 4.64 2.39 3.27
D (21) 2.03 4.28 3.40

(Zoom lens group data)
Group Start surface Focal length 1 1 39.42
2 6 -11.29
3 12 26.31
4 17 24.35
5 22 102.16

(Numerical values related to conditional expression (1))
f3a (focal length of the 3a lens group G _33a ) = 25.39
f3 (the focal length of the third lens group G ₃₃₎ = 26.31
f3a / f3 = 0.97

(Numerical value for conditional expression (2))
νd — 3a (Abbe number with respect to d-line of positive lens L ₃₃₁ ) = 81.56

(Numerical values related to conditional expression (3))
νd — 3 bp (Abbe number with respect to d line of positive lens L ₃₃₂ ) = 81.61

(Numerical values related to conditional expression (4))
f1 (the focal length of the first lens group G ₃₁₎ = 39.42
fw (focal length of the entire lens system at the wide angle end) = 10.09
f1 / fw = 3.91

(Numerical values related to conditional expression (5))
f3 (the focal length of the third lens group G ₃₃₎ = 26.31
fw (focal length of the entire lens system at the wide angle end) = 10.09
f3 / fw = 2.61

(Numerical values related to conditional expression (6))
νd — 4p (Abbe number with respect to d line of positive lens L ₃₄₁ ) = 81.56

  FIG. 6 is a diagram illustrating all aberrations of the zoom lens according to the third example. In the spherical aberration diagram, FNO represents the F number, the solid line is the d line (587.6 nm), the short broken line is the g line (435.8 nm), the long broken line is the C line (656.3 nm), and the alternate long and short dash line is the near infrared The characteristics of light rays (850.0 nm, indicated by IR in the figure) are shown. In the astigmatism diagram, ω represents a half angle of view and indicates the d-line characteristic. In the graph showing astigmatism, the solid line indicates the characteristics of the sagittal image plane (indicated by S in the figure), and the broken line indicates the characteristics of the meridional image plane (indicated by M in the figure). In the distortion diagram, ω represents a half angle of view and indicates the d-line characteristic.

FIG. 7 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to the fourth example. This figure shows the state of the wide-angle end of the lens system. The zoom lens includes a first lens group G ₄₁ having a positive refractive power, a second lens group G ₄₂ having a negative refractive power, and a third lens group having a positive refractive power in order from an object side (not shown). G ₄₃ , a fourth lens group G ₄₄ having a positive refractive power, and a fifth lens group G ₄₅ having a positive refractive power are arranged. A second lens group G ₄₂ between the third lens group G _43, an aperture stop STOP is positioned to define the predetermined diameter. A cover glass CG is disposed between the fifth lens group G ₄₅ and the image plane IMG.

The first lens group G ₄₁ includes, in order from the object side, a negative lens L _411, a positive lens L _412, a positive lens L _413, is formed are disposed. The negative lens L ₄₁₁ and the positive lens L ₄₁₂ are cemented.

The second lens group G ₄₂ is constituted in order from the object side, a negative lens L _421, a negative lens L _422, a positive lens L _423, is the arrangement. The negative lens L ₄₂₂ and the positive lens L ₄₂₃ are cemented.

The third lens group G ₄₃ includes a third a lens group G _43a having a positive refractive power and a third b lens group G _43b arranged in this order from the object side.

The third-a lens group G _43a is composed of a positive lens L ₄₃₁ . Aspherical surfaces are formed on both surfaces of the positive lens _L431 . The third-b lens group G _43b is configured by arranging a positive lens L ₄₃₂ and a negative lens L _{433 in} order from the object side. The negative lens L ₄₃₃ is arranged with the concave surface facing the image plane IMG side. The positive lens L ₄₃₂ and the negative lens L ₄₃₃ are cemented.

The fourth lens group G ₄₄ is constituted in order from the object side, a positive lens L _441, a positive lens L _442, a negative lens L _443, been arranged. Aspherical surfaces are formed on both surfaces of the positive lens _L441 . The positive lens L ₄₄₂ and the negative lens L ₄₄₃ are cemented.

The fifth lens group G ₄₅ includes a negative lens L ₄₅₁ and a positive lens L ₄₅₂ arranged in this order from the object side.

This zoom lens has the first lens group G ₄₁ , the aperture stop STOP, the third lens group G ₄₃ , and the fifth lens group G ₄₅ fixed to the image plane IMG, and the second lens group G ₄₂ and the second lens group G ₄₂ . The fourth lens group G ₄₄ is moved along the optical axis to perform zooming from the wide-angle end to the telephoto end. More specifically, the second lens group G ₄₂ by moving from the object side to the image plane IMG side performs zooming to the telephoto end from the wide-angle end, along the fourth lens group G ₄₄ to the optical axis It is moved to correct the focus position accompanying the zooming and focus.

  Various numerical data relating to the zoom lens according to Example 4 will be described below.

(Surface data)
r ₁ = 69.344
d ₁ = 1.00 nd ₁ = 1.92286 νd ₁ = 18.90
r ₂ = 44.788
d ₂ = 3.43 nd ₂ = 1.49700 νd ₂ = 81.61
r ₃ = -71.533
d ₃ = 0.10
r ₄ = 26.378
d ₄ = 2.61 nd ₃ = 1.59282 νd ₃ = 68.62
r ₅ = 56.467
d ₅ = D (5) (variable)
r ₆ = -72.354
d ₆ = 0.79 nd ₄ = 1.83481 νd ₄ = 42.72
r ₇ = 17.508
d ₇ = 1.90
r ₈ = -18.489
d ₈ = 0.74 nd ₅ = 1.58913 νd ₅ = 61.25
r ₉ = 20.606
d ₉ = 1.65 nd ₆ = 1.95906 νd ₆ = 17.47
r ₁₀ = 105.904
d ₁₀ = D (10) (variable)
r ₁₁ = ∞ (aperture stop)
d ₁₁ = 0.33
r ₁₂ = 15.600 (aspherical surface)
d ₁₂ = 3.05 nd ₇ = 1.43700 νd ₇ = 95.10
r ₁₃ = -40.403 (aspherical surface)
d ₁₃ = 0.10
r ₁₄ = 14.632
d ₁₄ = 2.97 nd ₈ = 1.43700 νd ₈ = 95.10
r ₁₅ = -116.489
d ₁₅ = 0.55 nd ₉ = 1.74950 νd ₉ = 35.33
r ₁₆ = 20.843
d ₁₆ = D (16) (variable)
r ₁₇ = 26.502 (aspherical surface)
d ₁₇ = 2.56 nd ₁₀ = 1.55332 νd ₁₀ = 71.68
r ₁₈ = -21.909 (aspherical surface)
d ₁₈ = 0.10
r ₁₉ = 9.161
d ₁₉ = 2.21 nd ₁₁ = 1.59282 νd ₁₁ = 68.62
r ₂₀ = 13.681
_{d 20 = 1.64 nd 12 = 1.72047} νd 12 = 34.71
r ₂₁ = 7.499
d ₂₁ = D (21) (variable)
r ₂₂ = 35.301
d ₂₂ = 0.63 nd ₁₃ = 1.72047 νd ₁₃ = 34.71
r ₂₃ = 9.077
d ₂₃ = 0.85
r ₂₄ = 16.565
d ₂₄ = 1.64 nd ₁₄ = 1.88100 νd ₁₄ = 40.14
r ₂₅ = -169.088
d ₂₅ = 6.29
r ₂₆ = ∞
d ₂₆ = 1.50 nd ₁₅ = 1.51633 νd ₁₅ = 64.14
r ₂₇ = ∞
d ₂₇ = 0.50
r ₂₈ = ∞ (image plane)

Cone coefficient (ε) and aspheric coefficient (A, B, C, D, E)
(Twelfth surface)
ε = 1.000,
A = 0, B = -1.39214 × 10 ⁻⁵ , C = 2.97629 × 10 ⁻⁷ ,
D = 1.70224 × 10 ⁻⁹ , E = 1.87499 × 10 ⁻¹⁰
(13th page)
ε = 1.000,
A = 0, B = 7.26258 × 10 ⁻⁵ , C = 5.91794 × 10 ⁻⁸ ,
D = 9.73322 × 10 ^-9 , E = 7.90494 × 10 ^-11
(Seventeenth surface)
ε = 1.000,
A = 0, B = -5.86444 × 10 ⁻⁶ , C = 2.53260 × 10 ⁻⁶ ,
D = -8.57985 × 10 ⁻⁸ , E = 3.11321 × 10 ⁻⁹
(18th page)
ε = 1.000,
A = 0, B = 7.04711 × 10 ⁻⁵ , C = 2.92069 × 10 ⁻⁶ ,
D = -1.16989 × 10 ⁻⁷ , E = 3.98777 × 10 ⁻⁹

(Various data)
Wide-angle end Medium focal position Telephoto end focal length 9.79 19.29 37.68
F number 1.65 1.83 2.16
Half angle of view (ω) 21.2 10.4 5.3
D (5) 1.01 10.24 18.13
D (10) 19.73 10.51 2.62
D (16) 5.04 2.91 2.29
D (21) 1.90 4.03 4.65

(Zoom lens group data)
Group Start surface Focal length 1 1 43.40
2 6 -11.72
3 12 27.80
4 17 21.03
5 22 400.22

(Numerical values related to conditional expression (1))
f3a (focal length of the 3a lens group G _43a ) = 26.19
f3 (the focal length of the third lens group G ₄₃₎ = 27.80
f3a / f3 = 0.94

(Numerical value for conditional expression (2))
νd — 3a (abbe number with respect to d line of positive lens L ₄₃₁ ) = 95.10

(Numerical values related to conditional expression (3))
νd — 3 bp (Abbe number with respect to d-line of positive lens L ₄₃₂ ) = 95.10

(Numerical values related to conditional expression (4))
f1 (the focal length of the first lens group G ₄₁₎ = 43.40
fw (focal length of the entire lens system at the wide angle end) = 9.79
f1 / fw = 4.43

(Numerical values related to conditional expression (5))
f3 (the focal length of the third lens group G ₄₃₎ = 27.80
fw (focal length of the entire lens system at the wide angle end) = 9.79
f3 / fw = 2.84

(Numerical values related to conditional expression (6))
νd — 4p (Abbe number with respect to d-line of positive lens L ₄₄₁ ) = 71.68

  FIG. 8 is a diagram illustrating various aberrations of the zoom lens according to the fourth example. In the spherical aberration diagram, FNO represents the F number, the solid line is the d line (587.6 nm), the short broken line is the g line (435.8 nm), the long broken line is the C line (656.3 nm), and the alternate long and short dash line is the near infrared The characteristics of light rays (850.0 nm, indicated by IR in the figure) are shown. In the astigmatism diagram, ω represents a half angle of view and indicates the d-line characteristic. In the graph showing astigmatism, the solid line indicates the characteristics of the sagittal image plane (indicated by S in the figure), and the broken line indicates the characteristics of the meridional image plane (indicated by M in the figure). In the distortion diagram, ω represents a half angle of view and indicates the d-line characteristic.

FIG. 9 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to the fifth example. This figure shows the state of the wide-angle end of the lens system. The zoom lens includes a first lens group G ₅₁ having a positive refractive power, a second lens group G ₅₂ having a negative refractive power, and a third lens group having a positive refractive power in order from an object side (not shown). G ₅₃ , a fourth lens group G ₅₄ having a positive refractive power, and a fifth lens group G ₅₅ having a positive refractive power are arranged. Between the second lens group G ₅₂ and the third lens group G ₅₃ , an aperture stop STOP that defines a predetermined aperture is disposed. Between the fifth lens group G ₅₅ and an image plane IMG, a cover glass CG is disposed.

The first lens group G ₅₁ includes, in order from the object side, a negative lens L _511, a positive lens L _512, a positive lens L _513, is formed are disposed. The negative lens L ₅₁₁ and the positive lens L ₅₁₂ are cemented.

The second lens group G ₅₂ is constituted in order from the object side, a negative lens L _521, a negative lens L _522, a positive lens L _523, is the arrangement. The negative lens L ₅₂₂ and the positive lens L ₅₂₃ are cemented.

The third lens group G ₅₃ includes a third a lens group G _53a having a positive refractive power and a third b lens group G _53b arranged in this order from the object side.

The third-a lens group G _53a includes a positive lens L ₅₃₁ . Aspherical surfaces are formed on both surfaces of the positive lens L ₅₃₁ . The third-b lens group G _53b includes a positive lens L ₅₃₂ and a negative lens L ₅₃₃ arranged in order from the object side. The negative lens L ₅₃₃ is disposed with the concave surface facing the image plane IMG side. The positive lens L ₅₃₂ and the negative lens L ₅₃₃ are cemented.

The fourth lens group G _54, configured in order from the object side, a positive lens L _541, a positive lens L _542, a negative lens L _543, been arranged. Aspherical surfaces are formed on both surfaces of the positive lens _L541 . The positive lens L ₅₄₂ and the negative lens L ₅₄₃ are cemented.

The fifth lens group G ₅₅ includes, in order from the object side, a negative lens L _551, a positive lens L _552, is formed are disposed.

In this zoom lens, the second lens group G ₅₂ and the fourth lens group G ₅₁ , the aperture stop STOP, the third lens group G ₅₃ , and the fifth lens group G ₅₅ are fixed to the image plane IMG. By moving the lens group G ₅₄ along the optical axis, zooming from the wide-angle end to the telephoto end is performed. More specifically, the second lens group G ₅₂ by moving from the object side to the image plane IMG side performs zooming to the telephoto end from the wide-angle end, along the fourth lens group G ₅₄ to the optical axis It is moved to correct the focus position accompanying the zooming and focus.

  Various numerical data relating to the zoom lens according to Example 5 will be described below.

(Surface data)
r ₁ = 70.305
d ₁ = 1.00 nd ₁ = 1.92286 νd ₁ = 18.90
r ₂ = 45.350
d ₂ = 3.30 nd ₂ = 1.49700 νd ₂ = 81.61
r ₃ = -73.194
d ₃ = 0.10
r ₄ = 26.348
d ₄ = 2.41 nd ₃ = 1.59282 νd ₃ = 68.62
r ₅ = 56.940
d ₅ = D (5) (variable)
r ₆ = -74.966
d ₆ = 0.55 nd ₄ = 1.80610 νd ₄ = 40.73
r ₇ = 15.661
d ₇ = 2.87
r ₈ = -17.632
d ₈ = 0.71 nd ₅ = 1.51680 νd ₅ = 64.20
r ₉ = 20.410
d ₉ = 1.60 nd ₆ = 1.95906 νd ₆ = 17.47
r ₁₀ = 93.892
d ₁₀ = D (10) (variable)
r ₁₁ = ∞ (aperture stop)
d ₁₁ = 0.36
r ₁₂ = 15.400 (aspherical surface)
d ₁₂ = 3.00 nd ₇ = 1.49710 νd ₇ = 81.56
r ₁₃ = -51.875 (aspherical surface)
d ₁₃ = 0.10
r ₁₄ = 16.926
d ₁₄ = 3.00 nd ₈ = 1.59282 νd ₈ = 68.62
r ₁₅ = -80.677
d ₁₅ = 0.55 nd ₉ = 1.74950 νd ₉ = 35.33
r ₁₆ = 16.192
d ₁₆ = D (16) (variable)
r ₁₇ = 24.157 (aspherical surface)
d ₁₇ = 2.50 nd ₁₀ = 1.55332 νd ₁₀ = 71.68
r ₁₈ = -22.021 (aspherical surface)
d ₁₈ = 0.10
r ₁₉ = 8.486
d ₁₉ = 2.22 nd ₁₁ = 1.43700 νd ₁₁ = 95.10
r ₂₀ = 14.090
d ₂₀ = 1.50 nd ₁₂ = 1.72047 νd ₁₂ = 34.71
r ₂₁ = 7.726
d ₂₁ = D (21) (variable)
r ₂₂ = 21.947
d ₂₂ = 0.50 nd ₁₃ = 1.72047 νd ₁₃ = 34.71
r ₂₃ = 8.287
d ₂₃ = 0.58
r ₂₄ = 17.693
d ₂₄ = 1.60 nd ₁₄ = 1.80420 νd ₁₄ = 46.50
r ₂₅ = -99.512
d ₂₅ = 6.29
r ₂₆ = ∞
d ₂₆ = 1.50 nd ₁₅ = 1.51633 νd ₁₅ = 64.14
r ₂₇ = ∞
d ₂₇ = 0.50
r ₂₈ = ∞ (image plane)

Cone coefficient (ε) and aspheric coefficient (A, B, C, D, E)
(Twelfth surface)
ε = 1.000,
A = 0, B = -1.25858 × 10 ⁻⁵ , C = 2.30429 × 10 ⁻⁸ ,
D = -8.21592 × 10 ^-9 , E = 1.63105 × 10 ^-10
(13th page)
ε = 1.000,
A = 0, B = 6.993665 × 10 ⁻⁵ , C = −9.99862 × 10 ⁻⁸ ,
D = -3.43382 × 10 ^-9 , E = 1.21864 × 10 ^-10
(Seventeenth surface)
ε = 1.000,
A = 0, B = -3.37976 × 10 ⁻⁵ , C = 3.03969 × 10 ⁻⁶ ,
D = -1.30373 × 10 ⁻⁷ , E = 3.66167 × 10 ⁻⁹
(18th page)
ε = 1.000,
A = 0, B = 3.84888 × 10 ⁻⁵ , C = 2.98942 × 10 ⁻⁶ ,
D = -1.36606 × 10 ⁻⁷ , E = 4.02689 × 10 ⁻⁹

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 9.70 19.07 37.50
F number 1.65 1.80 2.18
Half angle of view (ω) 21.2 10.4 5.3
D (5) 1.01 10.44 18.63
D (10) 20.04 10.61 2.42
D (16) 5.06 2.99 2.57
D (21) 1.87 3.94 4.36

(Zoom lens group data)
Group Start surface Focal length 1 1 43.68
2 6 -11.97
3 12 27.24
4 17 21.53
5 22 692.63

(Numerical values related to conditional expression (1))
f3a (focal length of the third-a lens group G _53a ) = 24.25
f3 (the focal length of the third lens group G ₅₃₎ = 27.24
f3a / f3 = 0.89

(Numerical value for conditional expression (2))
νd — 3a (Abbe number of the positive lens L ₅₃₁ with respect to the d line) = 81.56

(Numerical values related to conditional expression (3))
νd — 3 bp (Abbe number with respect to d line of positive lens L ₅₃₂ ) = 68.62

(Numerical values related to conditional expression (4))
f1 (the focal length of the first lens group G ₅₁₎ = 43.68
fw (focal length of the entire lens system at the wide angle end) = 9.70
f1 / fw = 4.50

(Numerical values related to conditional expression (5))
f3 (the focal length of the third lens group G ₅₃₎ = 27.24
fw (focal length of the entire lens system at the wide angle end) = 9.70
f3 / fw = 2.81

(Numerical values related to conditional expression (6))
νd — 4p (Abbe number with respect to d-line of positive lens L ₅₄₁ ) = 71.68

  FIG. 10 is a spherical aberration diagram illustrating various aberrations of the zoom lens according to Example 5, where FNO represents an F number, a solid line is a d-line (587.6 nm), a short broken line is a g-line (435.8 nm), The long broken line indicates the characteristic of C line (656.3 nm), and the alternate long and short dash line indicates the characteristic of near infrared light (850.0 nm, indicated by IR in the figure). In the astigmatism diagram, ω represents a half angle of view and indicates the d-line characteristic. In the graph showing astigmatism, the solid line indicates the characteristics of the sagittal image plane (indicated by S in the figure), and the broken line indicates the characteristics of the meridional image plane (indicated by M in the figure). In the distortion diagram, ω represents a half angle of view and indicates the d-line characteristic.

FIG. 11 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to the sixth example. This figure shows the state of the wide-angle end of the lens system. The zoom lens includes a first lens group G ₆₁ having a positive refractive power, a second lens group G ₆₂ having a negative refractive power, and a third lens group having a positive refractive power in order from an object side (not shown). G ₆₃ , a fourth lens group G ₆₄ having a positive refractive power, and a fifth lens group G ₆₅ having a negative refractive power are arranged. A second lens group G ₆₂ between the third lens group G _63, an aperture stop STOP is positioned to define the predetermined diameter. Between the fifth lens group G ₆₅ and an image plane IMG, a cover glass CG is disposed.

The first lens group G ₆₁ includes, in order from the object side, a negative lens L _611, a positive lens L _612, a positive lens L _613, is formed are disposed. The negative lens L ₆₁₁ and the positive lens L ₆₁₂ are cemented.

The second lens group G ₆₂ is constituted in order from the object side, a negative lens L _621, a negative lens L _622, a positive lens L _623, is the arrangement. The negative lens L ₆₂₂ and the positive lens L ₆₂₃ are cemented.

The third lens group G ₆₃ is configured by arranging, in order from the object side, a third a lens group G _63a having a positive refractive power and a third b lens group G _63b .

The third-a lens group G _63a is composed of a positive lens L ₆₃₁ . Aspherical surfaces are formed on both surfaces of the positive lens L ₆₃₁ . The third-b lens group G _63b includes a positive lens L ₆₃₂ , a negative lens L _633, and a positive lens L ₆₃₄ arranged in order from the object side. The negative lens L ₆₃₃ is disposed with the concave surface facing the image plane IMG side. The positive lens L ₆₃₂ and the negative lens L ₆₃₃ are cemented.

The fourth lens group G ₆₄ is constituted in order from the object side, a positive lens L _641, a positive lens L _642, a negative lens L _643, is the arrangement. Aspherical surfaces are formed on both surfaces of the positive lens L ₆₄₁ . The positive lens L ₆₄₂ and the negative lens L ₆₄₃ are cemented.

The fifth lens group G ₆₅ includes a negative lens L ₆₅₁ and a positive lens L ₆₅₂ arranged in this order from the object side.

This zoom lens has the first lens group G ₆₁ , the aperture stop STOP, the third lens group G ₆₃ , and the fifth lens group G ₆₅ fixed to the image plane IMG, and the second lens group G ₆₂ and the second lens group G ₆₂ . by moving the fourth lens group G ₆₄ along the optical axis, and performs zooming from the wide-angle end to the telephoto end. More specifically, the second lens group G ₆₂ by moving from the object side to the image plane IMG side performs zooming to the telephoto end from the wide-angle end, along the fourth lens group G ₆₄ to the optical axis It is moved to correct the focus position accompanying the zooming and focus.

  Various numerical data relating to the zoom lens according to Example 6 will be described below.

(Surface data)
r ₁ = 66.589
d ₁ = 1.00 nd ₁ = 1.92286 νd ₁ = 18.90
r ₂ = 43.260
d ₂ = 3.30 nd ₂ = 1.49700 νd ₂ = 81.61
r ₃ = -70.449
d ₃ = 0.10
r ₄ = 26.051
d ₄ = 2.43 nd ₃ = 1.59282 νd ₃ = 68.62
r ₅ = 58.572
d ₅ = D (5) (variable)
r ₆ = -60.735
d ₆ = 0.54 nd ₄ = 1.83481 νd ₄ = 42.72
r ₇ = 16.729
d ₇ = 1.86
r ₈ = -17.746
d ₈ = 0.54 nd ₅ = 1.51680 νd ₅ = 64.20
r ₉ = 19.269
d ₉ = 1.89 nd ₆ = 1.95906 νd ₆ = 17.47
r ₁₀ = 71.260
d ₁₀ = D (10) (variable)
r ₁₁ = ∞ (aperture stop)
d ₁₁ = 0.30
r ₁₂ = 18.000 (aspherical surface)
d ₁₂ = 2.45 nd ₇ = 1.49710 νd ₇ = 81.56
r ₁₃ = -94.976 (aspherical surface)
d ₁₃ = 0.10
r ₁₄ = 14.789
d ₁₄ = 2.75 nd ₈ = 1.43700 νd ₈ = 95.10
r ₁₅ = -70.638
d ₁₅ = 0.55 nd ₉ = 1.67300 νd ₉ = 38.15
r ₁₆ = 19.180
d ₁₆ = 0.92
r ₁₇ = 48.778
d ₁₇ = 1.43 nd ₁₀ = 1.43700 νd ₁₀ = 95.10
r ₁₈ = -134.743
d ₁₈ = D (18) (variable)
r ₁₉ = 23.492 (aspherical surface)
d ₁₉ = 2.35 nd ₁₁ = 1.49710 νd ₁₁ = 81.56
r ₂₀ = -21.793 (aspherical surface)
d ₂₀ = 0.10
r ₂₁ = 8.770
d ₂₁ = 2.21 nd ₁₂ = 1.43700 νd ₁₂ = 95.10
r ₂₂ = 12.896
d ₂₂ = 1.76 nd ₁₃ = 1.72047 νd ₁₃ = 34.71
r ₂₃ = 7.825
d ₂₃ = D (23) (variable)
r ₂₄ = 35.697
d ₂₄ = 0.54 nd ₁₄ = 1.67300 νd ₁₄ = 38.15
r ₂₅ = 8.387
d ₂₅ = 0.68
r ₂₆ = 16.486
d ₂₆ = 1.43 nd ₁₅ = 1.88100 νd ₁₅ = 40.14
r ₂₇ = -346.237
d ₂₇ = 6.29
r ₂₈ = ∞
d ₂₈ = 1.50 nd ₁₆ = 1.51633 νd ₁₆ = 64.14
r ₂₉ = ∞
d ₂₉ = 0.50
r ₃₀ = ∞ (image plane)

Cone coefficient (ε) and aspheric coefficient (A, B, C, D, E)
(Twelfth surface)
ε = 1.000,
A = 0, B = 9.65538 × 10 ⁻⁶ , C = 8.55980 × 10 ⁻⁷ ,
D = -2.16976 × 10 ⁻⁸ , E = 3.23657 × 10 ⁻¹⁰
(13th page)
ε = 1.000,
A = 0, B = 6.557015 × 10 ⁻⁵ , C = 1.06472 × 10 ⁻⁶ ,
D = -2.60488 × 10 ⁻⁸ , E = 3.70184 × 10 ⁻¹⁰
(19th page)
ε = 1.000,
A = 0, B = -6.56513 × 10 ⁻⁵ , C = 2.79634 × 10 ⁻⁶ ,
D = -1.07095 × 10 ⁻⁷ , E = 2.31882 × 10 ⁻⁹
(20th page)
ε = 1.000,
A = 0, B = 2.52689 × 10 ⁻⁵ , C = 2.29387 × 10 ⁻⁶ ,
D = -8.45728 × 10 ^-8 , E = 2.65526 × 10 ^-9

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 9.90 19.43 38.12
F number 1.65 1.81 2.13
Half angle of view (ω) 20.9 10.3 5.2
D (5) 0.99 10.17 18.10
D (10) 19.51 10.33 2.40
D (18) 4.92 2.93 2.83
D (23) 1.88 3.87 3.98

(Zoom lens group data)
Group Start surface Focal length 1 1 41.74
2 6 -11.56
3 12 25.76
4 19 22.82
5 24 -340.81

(Numerical values related to conditional expression (1))
f3a (focal length of the 3a lens group G _63a ) = 30.66
f3 (the focal length of the third lens group G ₆₃₎ = 25.76
f3a / f3 = 1.19

(Numerical value for conditional expression (2))
νd — 3a (abbe number with respect to d line of positive lens L ₆₃₁ ) = 81.56

(Numerical values related to conditional expression (3))
νd — 3 bp (Abbe number with respect to d line of positive lens L ₆₃₂ ) = 95.10

(Numerical values related to conditional expression (4))
f1 (the focal length of the first lens group G ₆₁₎ = 41.74
fw (focal length of the entire lens system at the wide angle end) = 9.90
f1 / fw = 4.22

(Numerical values related to conditional expression (5))
f3 (the focal length of the third lens group G ₆₃₎ = 25.76
fw (focal length of the entire lens system at the wide angle end) = 9.90
f3 / fw = 2.60

(Numerical values related to conditional expression (6))
νd — 4p (Abbe number of the positive lens L ₆₄₁ with respect to the d line) = 81.56

  FIG. 12 is a diagram illustrating various aberrations of the zoom lens according to the sixth example. In the spherical aberration diagram, FNO represents the F number, the solid line is the d line (587.6 nm), the short broken line is the g line (435.8 nm), the long broken line is the C line (656.3 nm), and the alternate long and short dash line is the near infrared The characteristics of light rays (850.0 nm, indicated by IR in the figure) are shown. In the astigmatism diagram, ω represents a half angle of view and indicates the d-line characteristic. In the graph showing astigmatism, the solid line indicates the characteristics of the sagittal image plane (indicated by S in the figure), and the broken line indicates the characteristics of the meridional image plane (indicated by M in the figure). In the distortion diagram, ω represents a half angle of view and indicates the d-line characteristic.

In the numerical data in each of the above embodiments, r ₁ , r ₂ ,... Are the curvature radii of the lens surfaces and the like, d ₁ , d ₂ ,. ... Nd ₁ , nd ₂ ,... Represents the refractive index with respect to the d-line (587.6 nm) of the lens, and νd ₁ , νd ₂ ,. . The unit of length is all “mm”, and the unit of angle is “°”. Note that the sign of the radius of curvature is positive when convex toward the object side.

  Each of the aspherical shapes has a height in the direction perpendicular to the optical axis as H, a displacement amount in the optical axis direction at the height H when the top of the lens surface is the origin, X, a paraxial radius of curvature as R, When the cone coefficient is ε, the second-order, fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients are A, B, C, D, and E, respectively, and the image plane direction is positive, expressed.

  As shown in each of the above examples, by satisfying the above conditional expressions, chromatic aberration was well corrected for light in a wide wavelength range from the visible light region to the near infrared region, and high resolution was provided. A small zoom lens can be realized.

<Application example>
Next, an example in which the zoom lens according to the present invention is applied to an imaging apparatus will be described. FIG. 13 is a diagram illustrating an example of an imaging apparatus including the zoom lens according to the present invention. As illustrated in FIG. 13, the imaging apparatus 100 includes a lens barrel unit 11 that houses a zoom lens 10 and a camera body 21 that includes a solid-state imaging device 20. The zoom lens 10 is zoomed by driving a mechanical mechanism (not shown). In FIG. 13, the zoom lens 10 according to the first embodiment (see FIG. 1) is shown. However, even the zoom lenses according to the second to sixth embodiments can be similarly mounted on the imaging apparatus 100. .

  In the imaging apparatus 100 including the zoom lens 10 and the solid-state imaging element 20, the image plane IMG illustrated in FIG. 1 corresponds to the imaging plane of the solid-state imaging element 20. As the solid-state imaging device 20, for example, a photoelectric conversion device such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) sensor can be used.

  In the imaging apparatus 100, 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 20. The solid-state imaging device 20 performs photoelectric conversion on the received light and outputs it as an electrical signal. This output signal is arithmetically processed by a signal processing circuit (not shown), and a digital image corresponding to the object image is generated. The digital image can be recorded on 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 is possible to realize a high-performance imaging device having a high resolving power with respect to light in a wide wavelength range up to the near infrared range as well as the visible light range.

  As described above, the zoom lens according to the present invention is useful for a small-sized imaging device equipped with a solid-state imaging device such as a CCD or a CMOS, and in particular, has a wide wavelength range from the visible light region to the near infrared region. This is suitable for an imaging device that requires high resolution even for light in the region.

_{G 11, G 21, G 31} , G 41, G 51, G 61 first lens group _{G 12, G 22, G 32} , G 42, G 52, G 62 second lens group G _13, G _23, G _{33 , G 43, G 53, G} 63 third lens group _{G 14, G 24, G 34} , G 44, G 54, G 64 fourth lens group _{G 15, G 25, G 35} , G 45, G 55, G ₆₅ 5th lens group _G13a , _G23a , _G33a , _G43a , _G53a , _G63a 3a lens group _G13b , _G23b , _G33b , _G43b , _G53b , _G63b 3b lens group _L111 , L ₁₂₁ , L ₁₂₂ , L ₁₃₃ , L ₁₄₃ , L ₁₅₁ , L ₂₁₁ , L ₂₂₁ , L ₂₂₂ , L ₂₃₃ , L ₂₄₃ , L ₂₅₁ , L ₃₁₁ , L ₃₂₁ , L ₃₂₂ , L ₃₃₃ , L ₃₄₃ , L ₃₅₁ , L ₄₁₁ , L ₄₂₁ , L ₄₂₂ , L ₄₃₃ , L ₄₄₃ , L ₄₅₁ , L ₅₁₁ , L ₅₂₁ , L ₅₂₂ , L ₅₃₃ , L ₅₄₃ , L ₅₅₁ , L ₆₁₁ , L ₆₂₁ , L ₆₂₂ , L ₆₃₃ , L _643, L ₆₅₁ negative lens _{L 112, L 113, L 123} , L 131, L 132 , _L141 , _L142 , _L152 , _L212 , _L213 , _L223 , _L231 , _L232 , _L241 , _L242 , _L252 , _L312 , _L313 , _L323 , _L331 , _L332 , L ₃₄₁ , L ₃₄₂ , L ₃₅₂ , L ₄₁₂ , L ₄₁₃ , L ₄₂₃ , L ₄₃₁ , L ₄₃₂ , L ₄₄₁ , L ₄₄₂ , L ₄₅₂ , L ₅₁₂ , L ₅₁₃ , L ₅₂₃ , L ₅₃₁ , L ₅₃₂ , L ₅₄₁ , L ₅₄₂ , L ₅₅₂ , L ₆₁₂ , L ₆₁₃ , L ₆₂₃ , L ₆₃₁ , L ₆₃₂ , L ₆₃₄ , L ₆₄₁ , L ₆₄₂ , L ₆₅₂ positive lens STOP aperture stop CG cover glass IMG image surface 10 zoom lens 11 lens barrel Unit 20 Solid-state imaging device 21 Camera body 100 Imaging device

Claims (7)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refractive power, which are arranged in order from the object side. A fourth lens group, and a fifth lens group;
In the zoom lens that performs zooming from the wide-angle end to the telephoto end by relatively changing the interval on the optical axis of each lens group while fixing the first lens group and the third lens group,
The third lens group is composed of a 3a lens group and a 3b lens group, which are arranged in order from the object side,
The 3a lens group is composed of one positive lens,
The 3b lens group includes at least one positive lens and at least one negative lens,
A zoom lens that satisfies the following conditional expression:
(1) 0.7 ≦ f3a / f3 ≦ 1.3
(2) 68 ≦ νd — 3a
Here, f3a represents the focal length of the 3a lens group, f3 represents the focal length of the third lens group, and νd_3a represents the Abbe number with respect to the d-line of the positive lens constituting the 3a lens group.   2. The zoom lens according to claim 1, wherein, among the negative lenses included in the third lens group, the negative lens disposed closest to the object side has a concave surface facing the image side. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
(3) 63 ≦ νd — 3 bp
Here, νd — 3bp indicates the Abbe number with respect to the d-line of the positive lens arranged closest to the object side among the positive lenses included in the third lens group. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
(4) 2.7 ≦ f1 / fw ≦ 6.2
Here, f1 represents the focal length of the first lens group, and fw represents the focal length of the entire lens system at the wide angle end. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
(5) 1.6 ≦ f3 / fw ≦ 4.1
Here, fw represents the focal length of the entire lens system at the wide angle end. The fourth lens group includes two positive lenses,
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
(6) 63 ≦ νd — 4p
Here, νd — 4p represents the Abbe number with respect to the d line of the positive lens disposed closest to the object side among the positive lenses included in the fourth lens group.   An image pickup apparatus comprising: the zoom lens according to claim 1; and a solid-state image pickup device that converts an optical image formed by the zoom lens into an electrical signal.

Images