JP2013257600A - Zoom lens and image capturing device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens which corrects chromatic aberration, spherical aberration, coma aberration, and the like in good balance and exhibits good optical properties over the entire zoom range.SOLUTION: A zoom lens includes a first lens group having positive refractive power, a second lens group having negative refractive power, and succeeding lens groups including a lens group having positive refractive power, all arranged in order from an object side to an image side. Zooming is performed by moving the lens groups such that the distance between the first lens group and the second lens group becomes longer at a telephoto end than at a wide angle end. The first lens group has at least one negative lens. An Abbe number νd1n and a partial dispersion ratio θgF1n of material of the at least one negative lens, a focal length fT of the zoom lens at the telephoto end, a focal length f1 of the first lens group, and a refractive index Nd1n of the material of the at least one negative lens of the first lens group are each set appropriately.

Description

  The present invention relates to a zoom lens and an imaging apparatus having the same, and is particularly suitable for an imaging optical system such as a still camera, a video camera, a digital still camera, a TV camera, and a surveillance camera.

  In recent years, the number of pixels of an image sensor used in an image pickup apparatus such as a digital camera or a video camera has been increased. In addition to correcting monochromatic (single wavelength) aberrations such as spherical aberration and coma, the photographic lens used in an imaging device equipped with such an image sensor also corrects chromatic aberration well so that there is no color blur in the white light source. Therefore, the zoom lens is required to have a high resolution.

  In addition, it is desired to have a high zoom ratio (high zoom ratio) in order to enlarge the photographing area. In particular, in a telephoto type zoom lens having a high zoom ratio and a long focal length on the telephoto side, the secondary spectrum is favorably corrected in addition to the primary achromatic color as a correction of chromatic aberration for high resolution. It is desired.

  As a zoom lens having a high zoom ratio, a succeeding lens group including a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a lens group having a positive refractive power is arranged in order from the object side to the image side. A so-called positive lead type zoom lens is also known. As a positive lead type zoom lens, there is known a zoom lens having four or more lens groups in which an anomalous dispersion material is used as the lens material of the first lens group and chromatic aberration (secondary spectrum) is corrected well (see FIG. Patent Document 1).

  In addition, in order from the object side, a lens made of a material having low dispersion and anomalous dispersion is used for the first lens group in a zoom lens having a four-group structure including lens groups having positive, negative, positive, and positive refractive powers. Zoom lenses are known (Patent Documents 2 and 3). In addition, in order from the object side, there is a zoom lens using a lens made of a material having anomalous dispersion in the first lens group in a zoom lens having a five-group structure including lens groups having positive, negative, positive, negative, and positive refractive power. Known (Patent Documents 4 and 5). In addition, a zoom lens is known in which chromatic aberration is improved by using a replica layer made of an energy curable transparent resin having anomalous dispersion as compared with optical glass (Patent Document 6).

Japanese Patent Laid-Open No. 2002-62478 JP 2005-345892 A JP 2001-194590 A JP 2006-349947 A JP 2007-298555 A JP 2008-191286 A

  A positive lead type zoom lens is relatively easy to achieve a high zoom ratio while reducing the size of the entire system. However, in a positive lead type zoom lens, when a high zoom ratio is achieved, a secondary spectrum of axial chromatic aberration is often generated in the zoom region on the telephoto side. In the above-described 4-group zoom lens and 5-group zoom lens, the incident light height is high in the first lens group in the telephoto range, and the above-described axial chromatic aberration is mainly generated in the first lens group.

  In order to reduce the secondary spectrum at this time, it is important to correct with the first lens group in which the height of the paraxial light beam becomes high at the telephoto end. In order to reduce the secondary spectrum of axial chromatic aberration at this time in the first lens group, it is effective to use a low dispersion and anomalous dispersion material for the lenses in the first lens group.

  However, in general, an optical material having low dispersion and anomalous dispersion has a low refractive index as represented by fluorite. Therefore, when the refractive power of the lens is changed in order to correct a desired secondary spectrum, it is necessary to greatly change the curvature of the lens. Further, in the first lens group of the positive lead type zoom lens described above, the height of the object paraxial light beam is increased at the telephoto end, so that a large amount of spherical aberration and coma aberration are generated in addition to axial chromatic aberration.

  For this reason, if only an optical material having low dispersion and anomalous dispersion or a resin material having a low refractive index is used, it is difficult to satisfactorily correct chromatic aberration, spherical aberration, coma and the like at the telephoto end. In order to satisfactorily correct chromatic aberration, spherical aberration, coma and the like, the number of lenses constituting the first lens group may be increased. However, when the number of lenses in the first lens group increases, the total lens length becomes longer, and it becomes very difficult to reduce the size of the entire system.

  An object of the present invention is to provide a zoom lens capable of correcting chromatic aberration, spherical aberration, coma, and the like in a positive lead type zoom lens in a well-balanced manner and obtaining good optical characteristics over the entire zoom range. .

The zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent lens group including a lens group having a positive refractive power. In the zoom lens that performs zooming by moving the lens group so that the distance between the first lens group and the second lens group is wider at the telephoto end than at the wide-angle end, the first lens group includes at least one negative lens. The lens has an Abbe number and a partial dispersion ratio of νd1n and θgF1n, respectively, a focal length at the telephoto end of the zoom lens is fT, a focal length of the first lens group is f1, When the refractive index of the material of at least one negative lens of the first lens group is Nd1n,
−1.68 × 10 ⁻³ × νd1n + 0.585 <θgF1n <3.15 × 10 ⁻⁴ × νd1n ² −1.86 × 10 ⁻² × νd1n + 0.878
5 <νd1n <27
0.3 <f1 / fT ≦ 0.755
1.8 <Nd1n <2.4
It is characterized by satisfying the following conditions.

In addition, 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 lens group having a positive refractive power in order from the object side to the image side. In the zoom lens that performs zooming by moving the lens group so that the distance between the first lens group and the second lens group is wider at the telephoto end than at the wide-angle end, the first lens group is at least A negative lens, the Abbe number and partial dispersion ratio of the material of the at least one negative lens are νd1n and θgF1n, respectively, the focal length at the wide angle end of the zoom lens is fW, and the focal length at the telephoto end of the zoom lens Is fT and the F-number at the telephoto end is FnoT.
−1.68 × 10 ⁻³ × νd1n + 0.585 <θgF1n <3.15 × 10 ⁻⁴ × νd1n ² −1.86 × 10 ⁻² × νd1n + 0.878
5 <νd1n <27
3.2 <(fT / fW) / FnoT <15.0
It is characterized by satisfying the following conditions.

  According to the present invention, it is possible to obtain a zoom lens that can correct chromatic aberration and correct spherical aberration, coma, and the like in a well-balanced manner, and that can provide good optical characteristics over the entire zoom range.

Lens cross-sectional view at the wide-angle end of the zoom lens of Example 1 Aberration diagram of zoom lens of Example 1 Lens sectional view at the wide-angle end of the zoom lens according to Embodiment 2 Aberration diagram of zoom lens of Example 2 Lens sectional view at the wide-angle end of the zoom lens according to Embodiment 3 Aberration diagram of zoom lens of Example 3 Lens sectional view at the wide-angle end of the zoom lens according to Embodiment 4 Aberration diagram of zoom lens of Example 4 Lens sectional view at the wide-angle end of the zoom lens according to Embodiment 5 Aberration diagram of zoom lens of Example 5 Lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 6 Aberration diagram of zoom lens of Example 6 Lens cross-sectional view at the wide-angle end of the zoom lens according to the seventh exemplary embodiment Aberration diagram of zoom lens of Example 7 Lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 8 Aberration diagrams of the zoom lens of Example 8 Explanatory drawing which shows the relationship between Abbe number νd and partial dispersion ratio θgF Schematic diagram of main parts of an imaging apparatus of the present invention Schematic diagram of main parts of an imaging apparatus of the present invention

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent lens group including a lens group having a positive refractive power. ing. The distance between the lens groups changes during zooming. At this time, zooming is performed so that the distance between the first lens unit and the second lens unit at the telephoto end is wider than at the wide-angle end. The first lens group has at least one negative lens. The at least one negative lens is made of a material that satisfies conditional expressions (1) and (2) described later.

  FIG. 1 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to the first exemplary embodiment of the present invention. FIGS. 2A, 2B, and 2C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end (long focal length end), respectively, of the zoom lens according to the first exemplary embodiment. FIG. 3 is a lens cross-sectional view at the wide-angle end of the zoom lens according to the second embodiment of the present invention. 4A, 4B, and 4C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the second embodiment.

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

  FIG. 9 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Example 5 of the present invention. FIGS. 10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 5 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively. FIG. 11 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Example 6 of the present invention. 12A, 12B, and 12C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 6, respectively.

  FIG. 13 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Example 7 of the present invention. FIGS. 14A, 14B, and 14C are aberration diagrams of the zoom lens of Embodiment 7 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively. FIG. 15 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Example 8 of the present invention. FIGS. 16A, 16B, and 16C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens of Example 8. FIGS. FIG. 17 is an explanatory diagram showing the relationship between the Abbe number νd and the partial dispersion ratio θgF. FIG. 18 is a schematic view of the main part when the zoom lens of the present invention is applied to a video camera (imaging device).

  FIG. 19 is a schematic view of a main part when the zoom lens of the present invention is applied to a digital camera (imaging device).

  The zoom lens of each embodiment is a photographing lens system used in an imaging apparatus such as a video camera, a digital camera, a silver salt film camera, or a TV camera. In addition, the zoom lens of each embodiment can also be used as a projection optical system for a projection apparatus (projector). In the lens cross-sectional view, the left side is the object side (front), and the right side is the image side (rear). In the lens cross-sectional view, if i is the order of the lens group from the object side, Bi indicates the i-th lens group. LR is a subsequent lens group having two or more lens groups.

  SP is an aperture stop. G is an optical block corresponding to an optical filter, a face plate, a low-pass filter, an infrared cut filter, or the like. IP is the image plane. The image plane IP corresponds to an imaging plane of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor when a zoom lens is used as a photographing optical system of a video camera or a digital camera. When a zoom lens is used as a photographing optical system of a silver salt film camera, it corresponds to a film surface. Arrows indicate the movement trajectory of each lens unit during zooming (variation) from the wide-angle end to the telephoto end.

  In the aberration diagrams, spherical aberration is shown for four wavelengths (d, g, C, and F lines). Astigmatism is shown for d-line (wavelength 587.56 nm) and g-line (wavelength 435.835 nm). In astigmatism, M (d) and S (d) indicate the meridional image surface and the sagittal image surface at the d-line. M (g) and S (g) indicate the meridional image plane and the sagittal image plane in the g-line. Lateral chromatic aberration is represented by the g-line. ω is a half angle of view, and Fno is an F number. In each of the following embodiments, the wide-angle end and the telephoto end refer to zoom positions when the zoom lens group is positioned at both ends of a range in which the zoom lens unit can move on the optical axis.

  In each of the embodiments, in order from the object side to the image side, a first lens unit B1 having a positive refractive power, a second lens unit B2 having a negative refractive power, and a subsequent lens unit including a lens unit having a positive refractive power A zoom lens having LR. During zooming, the lens group moves as indicated by the arrows. In particular, the distance between the first lens unit B1 and the second lens unit B2 changes during zooming. In the first to third, seventh, and eighth embodiments, the subsequent lens unit LR includes a third lens unit B3 having a positive refractive power and a fourth lens unit B4 having a positive refractive power.

  In Examples 4 and 6, the lens unit includes a third lens unit B3 having a positive refractive power, a fourth lens unit B4 having a negative refractive power, and a fifth lens unit B5 having a positive refractive power.

  In Example 5, the lens unit includes a third lens unit B3 having a negative refractive power and a fourth lens unit B4 having a positive refractive power. However, in each embodiment, the number of lens groups constituting the subsequent lens group LR and the refractive power of the lens groups are arbitrary, and it is sufficient that at least two lens groups are provided. In each embodiment, in order to ensure a high zoom ratio (high zoom ratio) and correct aberrations satisfactorily, the lens configuration includes lens groups having positive and negative refractive powers in order from the object side to the image side. . In each embodiment, the first lens unit B1 has at least one negative lens. The Abbe number and partial dispersion ratio of at least one negative lens material are νd1n and θgF1n, respectively.

At this time,
−1.68 × 10 ⁻³ × νd1n + 0.585 <θgF1n
<3.15 × 10 ⁻⁴ × νd1n ² −1.86 × 10 ⁻² × νd1n + 0.878
(1)
5 <νd1n <27 (2)
Is satisfied.

Conditional expressions (1) and (2) define the Abbe number νd1 and the partial dispersion ratio θgF1n of the material constituting the at least one negative lens when the first lens unit B1 has one or more negative lenses. Is. Note that the Abbe number νd and the partial dispersion ratio θgF of the material are Nd, NF, NC, and Ng when the refractive indexes of the Fraunhofer d-line, F-line, C-line, and g-line are Nd, NF, NC, and Ng.
νd = (Nd−1) / (NF−NC)
θgF = (Ng−NF) / (NF−NC)
Defined by

In each embodiment, the first lens unit B1 has at least one negative lens made of a material that satisfies the conditional expressions (1) and (2) at the same time. As a result, the primary achromatic color and the correction of the secondary spectrum are corrected well.

  FIG. 17 is a graph relating the Abbe number νd and the partial dispersion ratio θgF of the material. In FIG. 17, the Abbe number νd is taken on the horizontal axis, and the partial dispersion ratio θgF is taken on the vertical axis. In FIG. 17, the area | region regarding conditional expression (1), (2) is shown as the continuous line. Conditional expression (1) is a condition that defines the partial dispersion ratio of the material of at least one negative lens in the first lens unit B1. A material that satisfies the conditional expression (1) has anomalous dispersibility. A material outside the range of conditional expression (1) is not good because the anomalous dispersion necessary for reducing the secondary spectrum is low.

As one component of the glass (material) composition of the negative lens that satisfies the conditional expression (1), for example, when tellurium dioxide (TeO ₂ ) is contained in an amount of 20 mol% or more, the Abbe number νd and the partial dispersion ratio θgF are desired values. Can be. When compared with an optical element made of a replica layer such as a resin, this material has less restrictions on the environment resistance, ease of manufacture, and thickness of the optical element, and can have a strong refractive power. Since it is excellent in environmental resistance such as moisture absorption and temperature and has sufficient hardness, it can be disposed closest to the object side.

  More preferably, the numerical range of conditional expression (1) is set as in conditional expression (1a). According to this, it becomes easier to increase the refractive index of the glass material, and the effect of correcting various aberrations is increased, which is more preferable.

−1.68 × 10 ⁻³ × νd1n + 0.600 <θgF1n
<3.15 × 10 ⁻⁴ × νd1n ² −1.86 × 10 ⁻² × νd1n + 0.878
(1a)
More preferably, the conditional expression (1b) is set.

−1.68 × 10 ⁻³ × νd1n + 0.620 <θgF1n
<3.15 × 10 ⁻⁴ × νd1n ² −1.86 × 10 ⁻² × νd1n + 0.878
(1b)
More preferably, the conditional expression (1c) is set.

−1.68 × 10 ⁻³ × νd1n + 0.620 <θgF1n
<3.15 × 10 ⁻⁴ × νd1n ² −1.86 × 10 ⁻² × νd1n + 0.800
(1c)
Conditional expression (2) is a condition that defines the Abbe number of the material of at least one negative lens in the first lens unit B1. When the Abbe number increases beyond the upper limit value of conditional expression (2), the dispersion becomes too small, and it becomes difficult to correct primary chromatic aberration generated in the positive lens in the first lens unit B1. More preferably, the numerical range of conditional expression (2) is set as in the following conditional expression (2a). This increases the primary achromatic effect.

10 <νd1n <27 (2a)
More preferably, the conditional expression (2b) is set.

15 <νd1n <27 (2b)
More preferably, the conditional expression (2c) is set.

15 <νd1n <25 (2c)
In Examples 1 to 6, the first lens counted from the object side has anomalous dispersion. In Example 7, the first lens and the second lens counted from the object side have anomalous dispersion. In Example 8, the first lens and the third lens counted from the object side have anomalous dispersion. In particular, in each of the embodiments, a lens configuration having positive and negative refractive powers in order from the object side to the image side is used to achieve a small zoom lens with a high zoom ratio.

The material of at least one negative lens of the first lens group is configured to have high dispersion and anomalous dispersion so as to reduce the secondary spectrum on the telephoto side. Further, by satisfying conditional expressions (1) and (2) for at least one negative lens in the first lens group, it is possible to reduce the occurrence of chromatic aberration of magnification at the wide-angle end, and lenses following the second lens group. The group can be easily downsized.

  In each embodiment, in order to obtain a high zoom ratio and small zoom lens in which various aberrations such as longitudinal chromatic aberration, lateral chromatic aberration, and spherical aberration are corrected well, one or more of the following conditions are satisfied. Is good. The focal length of at least one negative lens of the first lens unit B1 is f1n, and the focal lengths of the first lens unit B1 and the second lens unit B2 are f1 and f2, respectively. The focal lengths at the wide-angle end and the telephoto end of the zoom lens are fW and fT, respectively. The F number at the telephoto end is FnoT. The thickness on the optical axis of at least one negative lens of the first lens group B1 is t1n, and the thickness on the optical axis of the lens having the smallest thickness on the optical axis in the second lens group B2 is t2min.

  The Knoop hardness of the material of at least one negative lens in the first lens group B1 is HK1n, and the Knoop hardness of the lens material having the minimum Knoop hardness in the second lens group B2 is HK2min. The refractive index of the material of at least one negative lens of the first lens unit B1 is Nd1n.

At this time,
0.9 <| f1n | / f1 <70.0 (3)
5.0 <fT / | f2 | <25.0 (4)
0.3 <f1 / fT <10.0 (5)
3.2 <(fT / fW) / FnoT <15.0 (6)
1.65 <Nd1n <2.50 (7)
3.0 <f1 / | f2 | <10.0 (8)
0.8 <t1n / t2min <5.0 (9)
0.5 <HK1n / HK2min (10)
It is sufficient to satisfy one or more of the following conditions.

  Conditional expression (3) defines the focal length of the negative lens having at least one high dispersion and anomalous dispersion in the first lens unit B1. If the focal length of the negative lens having high dispersion and anomalous dispersion exceeding the upper limit becomes too long, that is, if the refractive power of the negative lens becomes too weak, primary chromatic aberration correction in the first lens unit B1 is insufficient, Variation in chromatic aberration during zooming remains, which is not preferable. On the contrary, in order to sufficiently correct the primary chromatic aberration in the first lens unit B1, it is necessary to lengthen the entire length of the entire system, which makes it difficult to reduce the size.

  If the lower limit is exceeded and the focal length of the negative lens becomes too short, that is, if the refractive power of the negative lens becomes too strong, the Petzval sum will increase to the negative side and the field curvature will increase. Further, it is difficult to suppress high-order spherical aberration and chromatic spherical aberration in the first lens unit B1, which is not preferable.

  It is preferable to set the numerical range of conditional expression (3) as in the following conditional expression (3a). This facilitates correction of spherical aberration at the telephoto end.

0.9 <| f1n | / f1 <10.0 (3a)
Furthermore, it is preferable to set as in conditional expression (3b).

1.0 <| f1n | / f1 <5.0 (3b)
Conditional expression (4) defines the focal length of the entire system at the telephoto end by the focal length of the second lens unit B2. When the focal length of the second lens unit B2 is reduced beyond the upper limit of conditional expression (4), it is easy to increase the zoom ratio and shorten the total lens length, but the Petzval sum increases in the negative direction, and the field curvature Is unfavorable because it increases.

  When the focal length of the second lens unit B2 exceeds the lower limit of the conditional expression (4), the movement amount of the second lens unit B2 is increased or higher than that of the second lens unit B2 in order to increase the zoom ratio. It is necessary to increase the zooming effect in the rear subsequent lens group. Increasing the amount of movement of the second lens unit B2 is not preferable because the total lens length increases. Further, if the zooming action of the succeeding lens unit behind the second lens unit B2 is increased, the total length of the entire lens system becomes longer, which increases the number of lenses, which is not preferable.

  The numerical range of conditional expression (4) is preferably set as in the following conditional expression (4a). This is preferable because it is easy to suppress field curvature and astigmatism over the entire zoom range.

7.0 <fT / | f2 | <20.0 (4a)
The numerical value range of the other conditional expression (4) is preferably set as follows using the lower limit value of the conditional expression (4a).

7.0 <fT / | f2 | <25.0 (4b)
Conditional expression (5) defines the focal length of the entire system at the telephoto end by the focal length of the first lens unit B1.

  If the upper limit of conditional expression (5) is exceeded and the focal length of the first lens unit B1 becomes too long, it will be difficult to correct spherical aberration at the telephoto end, and this will follow the rear of the second lens unit B2. It is necessary to correct with the lens group. This is not good because the number of lenses in the subsequent lens group LR increases. If the lower limit of conditional expression (5) is exceeded and the focal length of the first lens unit B1 becomes too short, chromatic aberration increases at the telephoto end, which is not preferable. It is preferable to set the numerical range of conditional expression (5) as in the following conditional expression (5a). This facilitates correction of spherical aberration and downsizing of the entire system.

0.4 <f1 / fT <5.0 (5a)
In addition, the upper limit value of conditional expression (5) is preferably set as follows using the value of Example 6 described later.

0.3 <f1 / fT ≦ 0.755 (5b)
Conditional expression (6) defines the ratio of the focal lengths of the entire system at the wide-angle end and the telephoto end by the F number at the telephoto end.

  If the F number at the telephoto end becomes too large beyond the upper limit of conditional expression (6), spherical aberration and axial chromatic aberration can be easily corrected at the telephoto end, and high imaging performance can be obtained. This is not preferable because the image plane fluctuation increases. If the lower limit of conditional expression (6) is exceeded and the F-number at the telephoto end decreases, the number of lenses in the first lens unit B1 must be increased in order to correct spherical aberration at the telephoto end. This causes an increase in the radial direction of the first lens unit B1. As the radial direction increases, the flare component of off-axis rays increases in the entire zoom range, which is not preferable.

  If the upper limit of conditional expression (7) is exceeded and the negative lens material has a high refractive index, the radius of curvature of the lens surface increases, making it difficult to correct various aberrations, particularly to correct spherical aberration at the wide-angle end. If the refractive index of the negative lens material becomes lower than the lower limit of conditional expression (7), it is not preferable because the curvature radius of the lens surface becomes small and correction of astigmatism becomes difficult to give a predetermined refractive power. In addition, it is difficult to reduce the size of the entire system. The numerical range of conditional expression (7) is preferably set as in the following conditional expression (7a). This facilitates further downsizing of the entire system.

1.8 <Nd1n <2.4 (7a)
Conditional expression (8) sets the focal length of the second lens unit B2 appropriately, maintains an appropriate zoom ratio, and corrects the Petzval sum. If the upper limit of conditional expression (8) is exceeded, the aberration fluctuations of the first lens unit B1 and the second lens unit B2 during zooming will increase, and it will be particularly difficult to correct field curvature. Exceeding the lower limit of conditional expression (8) is not preferable because the amount of movement of the second lens unit B2 increases to increase the overall zoom ratio and radial direction in order to increase the zoom ratio.

  More preferably, the numerical range of the conditional expression (8) is set as the following conditional expression (8a).

4.0 <f1 / | f2 | <7.0 (8a)
Conditional expression (9) is for at least one negative lens of the first lens unit B1 to correct the chromatic aberration and to correct the spherical aberration and the coma aberration satisfactorily. Exceeding the upper limit of conditional expression (9) is not preferable because the negative lens of the first lens unit B1 becomes larger than the lens system. If the lower limit of conditional expression (9) is exceeded, it will be difficult to ensure the negative power (refractive power) of the negative lens of the first lens unit B1, and it will be difficult to correct spherical aberration and coma at the telephoto end. Become. More preferably, the numerical range of conditional expression (9) is set as in the following conditional expression (9a).

0.9 <t1n / t2min <4.0 (9a)
Conditional expression (10) defines an environment in which an external force is applied and deformation due to the weight of the glass and tightening. In conditional expression (10), Knoop hardness is one of the scales representing the hardness of industrial materials. Knoop hardness HK is calculated by dividing the test load by the indentation surface area.
HK = P / C _p L ²
here,
L ² = indentation surface area (unit: mm ² )
C _p = correction coefficient 0.070279
P = Weight (kgf)
It is. If the lower limit of conditional expression (10) is exceeded, the mechanical properties become insufficient, and when at least one negative lens of the first lens unit B1 is located closest to the subject, deformation or distortion occurs, which is not preferable. Further, it is desirable that the subsequent lens group LR has at least one aspherical lens.

  It is desirable to have an aspherical surface in order to make the F number at the wide angle end relatively small and to make the subsequent lens group a simple lens configuration. In addition, when the subsequent lens unit LR is combined into one lens system, it is desirable that the refractive power of the lens system be positive. By making the refractive power of the lens system that combines the subsequent lens groups LR positive, high optical performance can be achieved. Further, it is desirable that the subsequent lens unit LR has a third lens unit B3 having a positive refractive power.

  This is preferable for shortening the overall lens length and simplifying the lens system while ensuring a desired zoom ratio. In addition, it is preferable to use a lens including an aspherical surface in the third lens unit B3 because good imaging performance can be maintained even if the aperture ratio is large. As described above, according to each embodiment, a zoom lens having high imaging performance while having a high zoom ratio can be obtained by appropriately setting the variable power sharing by the configuration and power arrangement of each lens group. Yes.

  Next, the lens configuration of the zoom lens of each embodiment will be described. In the first, second, seventh, and eighth embodiments of FIGS. 1, 3, 13, and 15, when zooming from the wide-angle end to the telephoto end, the second lens unit B2 is moved to the image side to change the position as indicated by an arrow. Have done twice. Then, the image plane variation due to zooming is corrected by moving the fourth lens unit B4 to have a convex locus on the object side. In addition, a rear focus type that performs focusing by moving the fourth lens unit B4 on the optical axis is adopted.

  A solid curve 4a and a dotted curve 4b relating to the fourth lens unit B4 are movement trajectories for correcting image plane fluctuations accompanying zooming when focusing on an object at infinity and an object at close distance, respectively. Thus, by making the fourth lens unit B4 a locus convex toward the object side, the air between the third lens unit B3 and the fourth lens unit B4 can be effectively used, and the entire lens length can be shortened effectively. Has been achieved. In addition, this is done by moving from an infinitely distant object to a close object at the telephoto end.

  In Examples 1, 2, 7, and 8, the first lens unit B1 and the third lens unit B3 are fixed during zooming, and the total number of movable lens units is limited to two. This is preferable because the change in the overall lens length during zooming can be eliminated. Further, the aperture stop SP is fixed (immobilized) with respect to the image plane (image plane) during zooming. This eliminates the need for an actuator for moving the aperture stop SP during zooming, thus simplifying the configuration. The first lens unit B1, the third lens unit B3, and the aperture stop SP do not move in the optical axis direction for zooming and focusing. However, it may be moved as needed for aberration correction.

  In Example 3 of FIG. 5, during zooming from the wide-angle end to the telephoto end, the first lens unit B1 moves to the object side and the second lens unit B2 moves to the image side as indicated by the arrows. Further, the third lens unit B3 moves non-linearly toward the object side. The fourth lens unit L4 moves along a convex locus toward the object side to correct image plane fluctuations accompanying zooming. The aperture stop SP moves with a convex locus on the object side. A rear focus type is employed in which the fourth lens unit B4 is moved on the optical axis to perform focusing.

  When focusing from an infinitely distant object to a close object at the telephoto end, the fourth lens unit B4 is moved forward as indicated by an arrow 4c. A solid curve 4a and a dotted curve 4b relating to the fourth lens unit B4 are for correcting image plane fluctuations during zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and an object at close distance, respectively. The movement trajectory is shown. Rapid focusing is facilitated by moving the lightweight fourth lens unit B4 for focusing.

  In addition, by making the fourth lens unit B4 convex toward the object side in this way, the space between the third lens unit B3 and the fourth lens unit B4 is effectively used, and the total lens length is shortened. Has been achieved effectively. During zooming, the first lens unit B1 is positioned on the object side, the second lens unit B2 is positioned on the image plane side, and the third lens unit B3 is positioned on the object side at the telephoto end compared to the wide-angle end. doing. As a result, a large zoom ratio can be obtained while keeping the entire lens length small.

  Further, by moving the aperture stop SP so as to have a convex locus on the object side, it is possible to prevent the front lens diameter from increasing in order to secure peripheral rays at the intermediate zoom position, and to reduce the front lens diameter. We are trying to make it.

  In Example 4 of FIG. 7, during zooming from the wide-angle end to the telephoto end, the first lens unit B1 is moved to the object side as indicated by the arrow, and the second lens unit B2 is moved to the image side to perform main changes. Have done twice. The third lens unit B3 and the fourth lens unit B4 are moved to the object side. The fifth lens unit B5 is moved along a non-linear trajectory to correct image plane position fluctuations accompanying zooming. The stop SP moves independently to the object side. Further, a solid curve 5a and a dotted curve 5b relating to the fifth lens unit B5 correct image plane fluctuations accompanying zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and an object at close distance, respectively. The movement locus for this is shown.

  Thus, by moving the fifth lens unit B5 so as to have a convex locus on the object side, the space between the fourth lens unit B4 and the fifth lens unit B5 is effectively used and the total lens length is shortened. Has been achieved effectively.

  In the present embodiment, for example, focusing from an infinitely distant object to a close object on the object side is performed by extending the fifth lens unit B5 forward as indicated by a straight line 5c in FIG. In Example 5 of FIG. 9, in zooming from the wide-angle end to the telephoto end, the second lens unit B2 is moved to the image side to perform main zooming. Then, the third lens unit B3 is moved so as to have a convex locus on the object side, thereby correcting the image plane variation accompanying the zooming. Further, focusing is performed by the first lens unit B1. When focusing from an object at infinity to an object at a short distance, as indicated by an arrow F, the first lens unit B1 is moved forward (object side).

  In Example 5, the first lens unit B1 and the fourth lens unit B4 are fixed during zooming, and the total number of movable lens units is limited to two. According to this, a change in the total lens length during zooming can be eliminated. In Example 6 of FIG. 11, each lens group is moved as indicated by an arrow during zooming from the wide-angle end to the telephoto end. Specifically, during zooming from the wide-angle end to the telephoto end, the first lens unit B1 moves to the object side, and the second lens unit B2 moves nonlinearly to the image side. The third lens unit B3 is moved non-linearly toward the object side, the fourth lens unit B4 is moved non-linearly toward the image side, and the fifth lens unit B5 is moved non-linearly toward the object side.

  The aperture stop SP moves together with the third lens unit B3 during zooming, but may move separately or be fixed. When moved together, the number of groups divided by movement / movability is reduced, and the mechanical structure is easily simplified. A rear focus type in which focusing is performed by moving the second lens unit B2 on the optical axis is adopted. A solid curve 2a and a dotted curve 2b relating to the second lens unit B2 are used to correct image plane variation accompanying zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and an object at close distance, respectively. The movement trajectory is shown.

  In Example 6, for example, when focusing from an object at infinity to a near object at the telephoto end, the second lens unit B2 is moved forward as indicated by an arrow 2c. In Examples 3, 4, and 6, each lens group is moved during zooming to reduce the size of the lens system. This also suppresses aberration fluctuations during zooming.

  Next, an embodiment of a camcorder using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG. 18, and an embodiment of a digital still camera will be described with reference to FIG. In FIG. 18, reference numeral 10 denotes a camera body, and 11 denotes a photographing optical system constituted by any one of the zoom lenses described in the first to eighth embodiments. Reference numeral 12 denotes a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor that receives a subject image formed by the photographing optical system 11 and is built in the camera body. Reference numeral 13 is a finder for observing a subject image formed on the solid-state image sensor 12, which includes a liquid crystal display panel or the like.

  In FIG. 19, reference numeral 20 denotes a camera body, and reference numeral 21 denotes a photographing optical system constituted by any of the zoom lenses described in the first to eighth embodiments. Reference numeral 22 denotes a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor that receives a subject image formed by the photographing optical system 21 and is built in the camera body.

  Next, numerical examples corresponding to the respective examples will be shown. In the numerical example, i indicates the order of the surfaces from the object side. ri is the radius of curvature of the i-th surface in order from the object side, and di is the lens thickness and air spacing between the i-th and i + 1-th in order from the object side. ndi and νdi are respectively the refractive index and Abbe number of the material of the i-th optical member in order from the object side. Table 1 shows the relationship between the above-described conditional expressions and numerical examples. The aspherical shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, K is the conic constant, and A4 to A10 are each aspherical coefficients.

It is expressed by the following formula.
* Means a surface having an aspherical shape. “E−x” means 10 ^−x .

[Numerical Example 1]
Unit mm

Surface data surface number rd nd νd θgF
1 43.859 1.15 1.84666 26.8 0.57997
2 20.643 4.65 1.60300 65.4 0.54016
3 -520.777 0.20
4 19.644 3.31 1.69680 55.5 0.54335
5 61.808 (variable)
6 48.145 0.60 1.88300 40.8 0.56672
7 5.099 2.30
8 -22.405 0.60 1.77250 49.6 0.55205
9 12.593 0.50
10 10.103 1.47 1.92286 18.9 0.64952
11 50.485 (variable)
12 * 10.014 2.51 1.58313 59.4 0.54230
13 -156.394 1.40
14 (Aperture) ∞ 2.30
15 35.107 0.60 1.84666 23.8 0.62046
16 9.989 0.15
17 * 11.008 1.85 1.58313 59.4 0.54230
18 -94.159 (variable)
19 15.838 1.73 1.80400 46.6 0.55718
20 -18.707 0.55 1.92286 18.9 0.64952
21 -54.476 (variable)
22 ∞ 1.00 1.51633 64.1 0.53524
23 ∞ 1.00
Image plane ∞

Aspheric data 12th surface
K = -8.85802e-001 A 4 = 3.56682e-005 A 6 = -3.42001e-007
A 8 = 5.21683e-009

17th page
K = -3.29557e-002 A 4 = -2.10744e-004

Various data Zoom ratio 14.81
Wide angle Medium Telephoto focal length 4.25 22.44 62.97
F number 1.85 2.76 3.09
Angle of view 27.88 5.73 2.05
Image height 2.25 2.25 2.25
Total lens length 60.67 60.67 60.67
BF 8.43 12.33 5.99

d 5 0.65 14.91 19.41
d11 19.58 5.32 0.82
d18 6.14 2.25 8.59
d21 6.77 10.67 4.33

Zoom lens group data group Start surface Focal length
1 1 30.27
2 6 -5.70
3 12 16.49
4 19 16.50
5 22 ∞

[Numerical Example 2]
Unit mm

Surface data surface number rd nd νd θgF
1 44.369 1.20 1.84660 23.4 0.59564
2 22.958 4.69 1.60311 60.6 0.54143
3 -264.248 0.20
4 20.207 2.71 1.69680 55.5 0.54335
5 51.401 (variable)
6 27.518 0.80 1.88300 40.8 0.55718
7 6.535 2.28
8 -17.635 0.60 1.80400 46.6 0.55718
9 7.145 0.86
10 9.172 1.50 1.92286 18.9 0.64952
11 39.382 (variable)
12 (Aperture) ∞ 1.56
13 * 6.897 3.03 1.58313 59.4 0.54230
14 * -43.010 0.15
15 10.827 0.70 1.84666 23.8 0.62046
16 6.232 (variable)
17 12.586 2.96 1.48749 70.2 0.53001
18 -5.717 0.60 1.80610 33.3 0.58811
19 -9.733 (variable)
20 ∞ 2.00 1.51633 64.1 0.53524
21 ∞ 1.00
Image plane ∞

Aspherical data 13th surface
K = -5.41383e-001 A 4 = -1.52169e-005 A 6 = -1.89205e-007
A 8 = 9.89850e-009

14th page
K = -3.21918e + 001 A 4 = 2.03935e-004 A 6 = -2.22126e-006

Various data Zoom ratio
19.98
Wide angle Medium Telephoto focal length 3.62 9.89 72.39
F number 1.85 2.20 3.50
Angle of view 28.89 11.43 1.58
Image height 2.00 2.00 2.00
Total lens length 61.21 61.21 61.21
BF 8.96 11.54 5.17

d 5 0.55 10.63 20.72
d11 22.22 12.13 2.05
d16 5.64 3.07 9.43
d19 6.64 9.22 2.85

Zoom lens group data group Start surface Focal length
1 1 31.40
2 6 -5.43
3 12 17.64
4 17 15.60
5 20 ∞

[Numerical Example 3]
Unit mm

Surface data surface number rd nd νd θgF
1 65.395 1.50 2.10500 17.2 0.60817
2 43.930 4.82 1.49700 81.5 0.53752
3 -104.107 0.20
4 29.151 2.79 1.83481 42.7 0.56362
5 56.294 (variable)
6 41.126 0.90 1.83481 42.7 0.56362
7 12.363 4.73
8 -21.945 0.75 1.60311 60.6 0.54143
9 12.475 1.65
10 15.369 1.69 1.92286 18.9 0.64952
11 31.922 (variable)
12 (Aperture) ∞ (Variable)
13 * 9.798 3.34 1.58313 59.4 0.54230
14 81.572 3.98
15 15.028 0.70 2.10500 17.2 0.60817
16 8.998 1.09
17 78.174 1.35 1.84666 23.8 0.62046
18 -100.308 (variable)
19 ∞ (variable)
20 15.407 0.80 1.84666 23.8 0.62046
21 9.670 2.76 1.80400 46.6 0.55718
22 671.415 (variable)
23 ∞ 1.00 1.51633 64.1 0.53524
24 ∞ 1.50
Image plane ∞

Aspherical data 13th surface
K = -1.04021e + 000 A 4 = 1.85956e-004 A 6 = 3.69765e-005
A 8 = 5.71959e-007 A10 = -1.88292e-009
A 3 = -8.59213e-005 A 5 = -1.01902e-004 A 7 = -6.93498e-006

Various data Zoom ratio 11.55
Wide angle Medium Telephoto focal length 6.44 20.06 74.41
F number 2.00 2.90 3.50
Angle of view 29.20 10.18 2.77
Image height 3.60 3.60 3.60
Total lens length 83.06 83.77 86.22
BF 12.26 15.41 8.58

d 5 0.80 15.00 26.46
d11 24.77 8.56 3.00
d12 9.20 6.53 1.45
d18 1.16 2.46 4.31
d19 1.81 2.74 9.36
d22 10.10 13.25 6.42

Zoom lens group data group Start surface Focal length
1 1 45.10
2 6 -10.48
3 12 ∞
4 13 27.64
5 19 ∞
6 20 20.17
7 23 ∞

[Numerical Example 4]
Unit mm

Surface data surface number rd nd νd θgF
1 51.857 1.80 1.84660 23.4 0.59564
2 37.555 6.12 1.49700 81.5 0.53752
3 -9361.344 0.20
4 37.906 3.22 1.61272 58.7 0.54485
5 80.273 (variable)
6 47.453 1.00 1.88300 40.8 0.56672
7 8.290 3.81
8 27.180 0.80 1.88300 40.8 0.56672
9 16.395 2.25
10 -29.689 0.70 1.80610 33.3 0.58811
11 26.099 0.20
12 18.379 2.40 1.92286 18.9 0.64952
13 -87.594 (variable)
14 (Aperture) ∞ (Variable)
15 * 7.875 3.20 1.58313 59.4 0.54230
16 -34.469 1.63
17 116.346 0.80 1.76182 26.5 0.61353
18 8.090 0.50
19 11.124 0.70 2.00069 25.5 0.61357
20 5.663 2.70 1.69895 30.1 0.60291
21 81.297 (variable)
22 201.701 0.70 1.51633 64.1 0.53524
23 37.807 (variable)
24 * 16.564 2.50 1.58313 59.4 0.54230
25 -114.982 (variable)
26 ∞ 1.00 1.51633 64.1 0.53524
27 ∞ 2.00
Image plane ∞

Aspheric data 15th surface
K = -1.79527e-001 A 4 = -1.55788e-004 A 6 = -4.02659e-007
A 8 = -9.95380e-008 A10 = 2.12024e-009

24th page
K = 3.17692e + 000 A 4 = -1.15655e-004 A 6 = -3.79021e-007
A 8 = -2.08695e-008

Various data Zoom ratio 18.56
Wide angle Medium telephoto focal length 5.16 18.34 95.85
F number 2.85 3.61 5.27
Angle of view 36.88 11.93 2.32
Image height 3.88 3.88 3.88
Total lens length 86.76 92.18 118.76
BF 10.67 17.14 12.33

d 5 0.70 22.07 41.23
d13 27.76 9.82 3.52
d14 8.76 4.72 2.07
d21 1.64 0.95 5.02
d23 2.01 2.24 19.36
d25 8.01 14.48 9.67

Zoom lens group data group Start surface Focal length
1 1 63.72
2 6 -9.46
3 14 ∞
4 15 19.45
5 22 -90.25
6 24 25.00
7 26 ∞

[Numerical Example 5]
Unit mm

Surface data surface number rd nd νd θgF
1 1249.461 2.40 1.84660 23.4 0.59564
2 106.525 10.60 1.51633 64.1 0.53524
3 -277.435 0.20
4 132.704 7.80 1.60311 60.6 0.54143
5 -529.319 0.20
6 56.525 6.90 1.67790 55.3 0.54720
7 152.250 (variable)
8 64.335 1.00 1.77250 49.6 0.55205
9 18.382 6.01
10 -23.952 0.90 1.77250 49.6 0.55205
11 17.007 4.63 1.84666 23.8 0.62046
12 144.295 (variable)
13 -26.130 0.90 1.78800 47.4 0.55592
14 36.326 3.84 1.84666 23.8 0.62046
15 -1354.707 (variable)
16 (Aperture) ∞ 1.60
17 -1002.750 4.60 1.65844 50.9 0.55606
18 -26.453 0.20
19 213.896 2.53 1.48749 70.2 0.53001
20 -215.067 0.20
21 40.643 6.76 1.48749 70.2 0.53001
22 -28.446 1.20 1.83400 37.2 0.57752
23 -2366.634 35.00
24 65.474 4.96 1.48749 70.2 0.53001
25 -64.304 0.20
26 -139.780 1.20 1.83400 37.2 0.57752
27 50.625 6.25 1.48749 70.2 0.53001
28 -34.432 0.20
29 43.063 7.05 1.51742 52.4 0.55643
30 -28.766 1.20 1.80400 46.6 0.55718
31 67.190 0.20
32 44.873 3.72 1.54814 45.8 0.56852
33 -993.699 3.86
34 ∞ 30.00 1.60342 38.0 0.58349
35 ∞ 16.20 1.51633 64.1 0.53524
36 ∞ 6.00
Image plane ∞

Various data Zoom ratio 15.10
Wide angle Medium telephoto focal length 10.63 25.62 160.48
F number 2.05 2.20 2.40
Angle of view 25.20 11.04 1.78
Image height 5.00 5.00 5.00
Total lens length 217.41 217.41 217.41
BF 39.25 39.25 39.25

d 7 0.80 25.30 49.80
d12 52.91 25.24 5.29
d15 2.00 5.17 0.62

Zoom lens group data group Start surface Focal length
1 1 76.67
2 8 -14.23
3 13 -35.91
4 16 46.65

[Numerical Example 6]
Unit mm

Surface data surface number rd nd νd θgF
1 107.999 2.00 1.84660 23.4 0.59564
2 47.046 7.10 1.65160 58.5 0.54261
3 420.921 0.15
4 41.785 4.57 1.77250 49.6 0.55205
5 98.031 (variable)
6 59.864 1.20 1.80610 40.9 0.57012
7 11.552 4.90
8 -59.265 1.10 1.80400 46.6 0.55718
9 27.044 0.12
10 19.461 3.60 1.84666 23.8 0.62046
11 -43.915 0.34
12 -32.736 1.10 1.83481 42.7 0.56362
13 85.194 (variable)
14 (Aperture) ∞ 0.54
15 25.010 1.10 1.84666 23.8 0.62046
16 14.218 3.50 1.51633 64.1 0.53524
17 -103.599 0.15
18 38.687 2.30 1.71300 53.9 0.54581
19 -45.619 (variable)
20 -32.294 3.10 1.80518 25.4 0.61608
21 -16.435 1.20 1.80 400 46.6 0.55718
22 172.236 (variable)
23 49.504 6.90 1.48749 70.2 0.53001
24 -28.249 0.15
25 70.619 5.00 1.60311 60.6 0.54143
26 -41.413 3.29
27 * -27.525 1.50 1.84666 23.8 0.62046
28 -336.482 (variable)
Image plane ∞

Aspheric data 27th surface
K = 0.00000e + 000 A 4 = -1.27914e-005 A 6 = 2.89752e-009
A 8 = -8.58172e-011 A10 = 2.69813e-013
A 3 = 1.46741e-005

Various data Zoom ratio 4.10
Wide angle Medium Telephoto focal length
F number 3.62 4.91 5.82
Angle of view 40.98 20.68 11.97
Image height 21.64 21.64 21.64
Total lens length 119.84 139.04 151.84
BF 38.50 46.21 51.35

d 5 1.40 19.07 30.10
d13 11.05 4.86 1.49
d19 1.43 8.80 12.79
d22 12.56 5.18 1.19
d28 38.50 46.21 51.35

Zoom lens group data group Start surface Focal length
1 1 77.07
2 6 -12.85
3 14 21.02
4 20 -33.55
5 23 36.77

[Numerical Example 7]
Unit mm

Surface data surface number rd nd νd θgF
1 42.915 0.80 1.84660 23.4 0.59564
2 23.633 0.50 2.00800 10.2 0.56923
3 23.135 4.54 1.60311 60.6 0.54143
4 -378.880 0.20
5 20.801 2.70 1.69680 55.5 0.54335
6 54.133 (variable)
7 35.062 0.80 1.88300 40.8 0.56672
8 6.518 2.31
9 -21.225 0.50 1.77250 49.6 0.55205
10 7.227 0.88
11 9.085 1.49 1.92286 18.9 0.64952
12 32.295 (variable)
13 (Aperture) ∞ 1.56
14 * 7.193 3.37 1.58313 59.4 0.54230
15 * -35.550 0.15
16 11.989 0.70 1.84666 23.8 0.62046
17 6.706 (variable)
18 12.631 3.00 1.48749 70.2 0.53001
19 -5.729 0.60 1.80610 33.3 0.58811
20 -9.788 (variable)
21 ∞ 2.00 1.51633 64.1 0.53524
22 ∞ 1.00
Image plane ∞

Aspheric data 14th surface
K = -5.68472e-001 A 4 = -1.47503e-005 A 6 = -3.14527e-007
A 8 = -3.33402e-009

15th page
K = -1.97217e + 001 A 4 = 2.05875e-004 A 6 = -2.87688e-006

Various data Zoom ratio 19.94
Wide angle Medium telephoto focal length 3.63 9.85 72.40
F number 1.85 2.20 3.50
Angle of view 28.85 11.48 1.58
Image height 2.00 2.00 2.00
Total lens length 61.83 61.83 61.83
BF 8.84 11.42 5.19

d 6 0.55 10.80 21.05
d12 22.55 12.30 2.05
d17 5.79 3.21 9.44
d20 6.52 9.10 2.87

Zoom lens group data group Start surface Focal length
1 1 31.85
2 7 -5.50
3 13 17.64
4 18 15.72
5 21 ∞

[Numerical Example 8]
Unit mm

Surface data surface number rd nd νd θgF
1 44.412 1.20 1.84666 23.8 0.62046
2 22.580 4.38 1.60311 60.6 0.56923
3 -2093.893 0.20
4 22.190 0.55 2.00 800 10.2 0.56923
5 21.577 2.62 1.76735 49.6 0.56115
6 64.083 (variable)
7 44.076 0.80 1.88300 40.8 0.56672
8 6.320 2.08
9 -24.266 0.50 1.79909 47.1 0.56561
10 7.611 0.80
11 9.198 1.52 1.92286 18.9 0.64952
12 38.947 (variable)
13 (Aperture) ∞ 1.56
14 * 7.024 3.36 1.58313 59.4 0.54230
15 * -44.323 0.15
16 11.237 0.70 1.84666 23.8 0.62046
17 6.476 (variable)
18 12.608 3.04 1.48749 70.2 0.53001
19 -5.630 0.60 1.80610 33.3 0.58811
20 -9.706 (variable)
21 ∞ 2.00 1.51633 64.1 0.53524
22 ∞ 1.00
Image plane ∞

Aspheric data 14th surface
K = -5.35812e-001 A 4 = -9.25135e-006 A 6 = -2.55624e-007
A 8 = -3.52289e-009

15th page
K = -4.04570e + 001 A 4 = 2.09662e-004 A 6 = -2.84336e-006

Various data Zoom ratio 19.94
Wide angle Medium telephoto focal length 3.63 9.89 72.40
F number 1.85 2.20 3.50
Angle of view 28.85 11.43 1.58
Image height 2.00 2.00 2.00
Total lens length 61.88 61.88 61.88
BF 8.83 11.44 5.18

d 6 0.55 10.91 21.28
d12 22.78 12.41 2.05
d17 5.66 3.05 9.31
d20 6.51 9.12 2.86

Zoom lens group data group Start surface Focal length
1 1 32.02
2 7 -5.55
3 13 17.64
4 18 15.77
5 21 ∞

B1 first lens group, B2 second lens group, B3 third lens group, B4 fourth lens group, B5 fifth lens group, SP aperture stop, G glass block, IP image plane, dd line, gg line, CC line, FF line, M meridional image plane, S sagittal image plane

Claims (19)

In order from the object side to the image side, the first lens group having a positive refractive power, the second lens group having a negative refractive power, and a subsequent lens group including a lens group having a positive refractive power are formed. In a zoom lens that performs zooming by moving the lens group so that the distance between the first lens group and the second lens group is wide at the end, the first lens group includes at least one negative lens, The Abbe number and partial dispersion ratio of the material of one negative lens are νd1n and θgF1n, the focal length at the telephoto end of the zoom lens is fT, the focal length of the first lens group is f1, and at least one of the first lens group When the refractive index of the material of the two negative lenses is Nd1n,
−1.68 × 10 ⁻³ × νd1n + 0.585 <θgF1n <3.15 × 10 ⁻⁴ × νd1n ² −1.86 × 10 ⁻² × νd1n + 0.878
5 <νd1n <27
0.3 <f1 / fT ≦ 0.755
1.8 <Nd1n <2.4
A zoom lens characterized by satisfying the following conditions: When the focal length of the at least one negative lens is f1n,
0.9 <| f1n | / f1 <70.0
The zoom lens according to claim 1, wherein the following condition is satisfied. When the focal length at the wide angle end of the zoom lens is fW and the F number at the telephoto end is FnoT,
3.2 <(fT / fW) / FnoT <15.0
The zoom lens according to claim 1, wherein the following condition is satisfied. When the focal length of the second lens group is f2,
3.0 <f1 / | f2 | <10.0
The zoom lens according to claim 1, wherein the following condition is satisfied. When the thickness on the optical axis of the at least one negative lens is t1n, and the thickness on the optical axis of the lens with the smallest thickness on the optical axis in the second lens group is t2min,
0.8 <t1n / t2min <5.0
The zoom lens according to claim 1, wherein the following condition is satisfied. When the Knoop hardness of the material of the at least one negative lens is HK1n, and the Knoop hardness of the material of the lens having the smallest Knoop hardness in the second lens group is HK2min.
0.5 <HK1n / HK2min
The zoom lens according to claim 1, wherein the following condition is satisfied. 7. The subsequent lens group includes a third lens group having a positive refractive power and a fourth lens group having a positive refractive power in order from the object side to the image side. The zoom lens according to item 1. 7. The subsequent lens group includes a third lens group having a negative refractive power and a fourth lens group having a positive refractive power in order from the object side to the image side. The zoom lens according to item 1. The subsequent lens group includes, in order from the object side to the image side, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power. The zoom lens according to any one of claims 1 to 6. In order from the object side to the image side, the first lens group having a positive refractive power, the second lens group having a negative refractive power, and a subsequent lens group including a lens group having a positive refractive power are formed. In a zoom lens that performs zooming by moving the lens group so that the distance between the first lens group and the second lens group is wide at the end, the first lens group includes at least one negative lens, The Abbe number and partial dispersion ratio of one negative lens material are νd1n and θgF1n, the focal length at the wide-angle end of the zoom lens is fW, the focal length at the telephoto end of the zoom lens is fT, and the F-number at the telephoto end is When FnoT,
−1.68 × 10 ⁻³ × νd1n + 0.585 <θgF1n <3.15 × 10 ⁻⁴ × νd1n ² −1.86 × 10 ⁻² × νd1n + 0.878
5 <νd1n <27
3.2 <(fT / fW) / FnoT <15.0
A zoom lens characterized by satisfying the following conditions: When the focal length of the first lens group is f1,
0.3 <f1 / fT <10.0
The zoom lens according to claim 10, wherein the following condition is satisfied. When the focal length of the first lens group is f1, and the focal length of the second lens group is f2,
3.0 <f1 / | f2 | <10.0
The zoom lens according to claim 10 or 11, wherein the following condition is satisfied. When the thickness on the optical axis of the at least one negative lens is t1n, and the thickness on the optical axis of the lens with the smallest thickness on the optical axis in the second lens group is t2min,
0.8 <t1n / t2min <5.0
The zoom lens according to claim 10, wherein the following condition is satisfied. When the Knoop hardness of the material of the at least one negative lens is HK1n, and the Knoop hardness of the material of the lens having the smallest Knoop hardness in the second lens group is HK2min.
0.5 <HK1n / HK2min
The zoom lens according to claim 10, wherein the following condition is satisfied. 15. The subsequent lens group is configured by a third lens group having a positive refractive power and a fourth lens group having a positive refractive power in order from the object side to the image side. The zoom lens according to item 1. 15. The subsequent lens group includes a third lens group having a negative refractive power and a fourth lens group having a positive refractive power in order from the object side to the image side. The zoom lens according to item 1. The subsequent lens group includes, in order from the object side to the image side, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power. The zoom lens according to any one of claims 10 to 14. The zoom lens according to claim 1, wherein an image is formed on the photoelectric conversion element. An image pickup apparatus comprising: the zoom lens according to claim 1; and a photoelectric conversion element that receives an image formed by the zoom lens.