JP6439364B2 - Zoom lens system - Google Patents

Description

  The present invention relates to a zoom lens system, and more particularly to a large-aperture telephoto zoom lens system suitable for an imaging device such as a digital camera.

  In recent years, optical systems used in imaging devices such as digital cameras are required not only to have high optical performance but also to increase the focus speed. To that end, the focus lens group must be made smaller and lighter. Has been proposed. However, the conventional optical system is not at a satisfactory level because the compatibility between the optical performance and the reduction in size and weight of the focus lens group is insufficient.

  In Patent Documents 1-4, when a lens group is defined with a part where the lens interval changes during zooming as a boundary, a zoom of a four-group lens structure (Patent Documents 1, 2, 4) or a five-group lens structure (Patent Document 3). A lens system is disclosed. However, in any of the zoom lens systems disclosed in Patent Documents 1-4, since the power balance of each lens group is inappropriate, correction of various aberrations such as spherical aberration, coma aberration, and distortion aberration is insufficient. In Patent Documents 1 and 2, since focusing is performed in the second half of the first lens group having the largest diameter and the largest weight, the load during autofocusing is large and performance change (performance degradation) during focusing is large. In Patent Documents 3 and 4, focusing is performed with the third lens group having a relatively small diameter, so the load applied to the autofocus operation is small compared to Patent Documents 1 and 2, but this is advantageous, but the performance change during focusing (see FIG. There is a problem that the performance degradation is large.

JP 2008-216480 A JP 2009-288619 A JP 2010-160240 A JP 2011-158599 A

  The present invention has been made on the basis of the above awareness of the problems, and corrects various aberrations such as spherical aberration, coma aberration, distortion aberration, etc., and uses a focusing group with a small operation load, while performing focusing. An object of the present invention is to obtain a zoom lens system capable of suppressing changes (performance degradation).

In one aspect , the zoom lens system of the present invention includes, in order from the most object side, a first lens group having a positive refractive power and a second lens group having a negative refractive power, and is closest to the image side. Having an nth lens unit having a positive refractive power; the first lens unit and the nth lens unit are fixed with respect to the image plane during zooming from the short focal length end to the long focal length end , the second lens group is moved in the optical axis direction; between the second lens group and the n lens group, that has a first m lens unit having a positive refractive power; a first lens group, In order from the object side, it consists of a negative lens with a concave surface facing the image side, a positive lens with a convex surface facing the object side, a positive lens with a convex surface facing the object side, and a positive lens with a convex surface facing the object side The nth lens group has two or more positive lenses; and the following conditional expressions (1), (2) , (3) , (4) and (5) are satisfied.
(1) 1.23 <f1 / fn <1.50
(2) 1.20 <fn / fm <1.60
(3) νdp2>νdp1> νdp3
(4) Np1-Np2> 0
(5) νave> 68
However,
f1: the focal length of the first lens group,
fn: focal length of the nth lens group (n is a positive integer of 4 or more),
fm: focal length of the m-th lens group (m is a positive integer of 3 or more) ,
νdp1: Abbe number for the d-line of the positive lens located closest to the object side among the positive lenses in the first lens group,
νdp2: Abbe number for the d-line of the positive lens located second from the object side among the positive lenses in the first lens group,
νdp3: Abbe number for the d-line of the positive lens located third from the object side among the positive lenses in the first lens group,
Np1: the refractive index of the positive lens located closest to the object side among the positive lenses in the nth lens group with respect to the d-line,
Np2: refractive index with respect to d-line of the positive lens located second from the object side among the positive lenses in the nth lens group,
νave: average value of Abbe numbers for the d-line of the positive lens located closest to the object side and the second positive lens located from the object side among the positive lenses in the nth lens group
It is.
In another aspect, the zoom lens system of the present invention includes, in order from the most object side, a first lens group having a positive refractive power and a second lens group having a negative refractive power, and is closest to the image side. Having an nth lens unit having a positive refractive power; the first lens unit and the nth lens unit are fixed with respect to the image plane during zooming from the short focal length end to the long focal length end The second lens group moves in the optical axis direction; the m-th lens group having a positive refractive power is provided between the second lens group and the n-th lens group; In order from the object side, it consists of a negative lens with a concave surface facing the image side, a positive lens with a convex surface facing the object side, a positive lens with a convex surface facing the object side, and a positive lens with a convex surface facing the object side Satisfying the following conditional expressions (1), (2), (3); and the most object side lens in the nth lens group It is characterized in; between the image side of the lens, the following conditional expression (6), (7), that is positioned intermediate the positive lens that satisfies (8).
(1) 1.23 <f1 / fn <1.50
(2) 1.20 <fn / fm <1.60
(3) νdp2>νdp1> νdp3
(6) 0.5 <DnP / LDn <0.75
(7) 0.9 <fn / fnP <1.4
(8) 60 <νnP <75
However,
f1: the focal length of the first lens group,
fn: focal length of the nth lens group (n is a positive integer of 4 or more),
fm: focal length of the m-th lens group (m is a positive integer of 3 or more),
νdp1: Abbe number for the d-line of the positive lens located closest to the object side among the positive lenses in the first lens group,
νdp2: Abbe number for the d-line of the positive lens located second from the object side among the positive lenses in the first lens group,
νdp3: Abbe number for the d-line of the positive lens located third from the object side among the positive lenses in the first lens group,
DnP: distance from the object side surface of the most object side lens in the nth lens group to the object side surface of the intermediate positive lens,
LDn: Group thickness of the nth lens group,
fnP: focal length of the intermediate positive lens in the nth lens group,
νnP: Abbe number for the d-line of the intermediate positive lens in the nth lens group,
It is.
In another aspect, the zoom lens system of the present invention includes, in order from the most object side, a first lens group having a positive refractive power and a second lens group having a negative refractive power, and is closest to the image side. Having an nth lens unit having a positive refractive power; the first lens unit and the nth lens unit are fixed with respect to the image plane during zooming from the short focal length end to the long focal length end The second lens group moves in the optical axis direction; the mth lens group having a positive refractive power is provided between the second lens group and the nth lens group; the second lens group and the second lens group a lens unit having a negative refractive power different from that of the mth lens unit is provided between the nth lens unit; the first lens unit is a negative lens having a concave surface directed toward the image side in order from the object side. And a positive lens having a convex surface facing the object side, a positive lens having a convex surface facing the object side, and a positive lens having a convex surface facing the object side. ; And the following conditional expression (1), (2), (3), to satisfy the (9); and characterized by.
(1) 1.23 <f1 / fn <1.50
(2) 1.20 <fn / fm <1.60
(3) νdp2>νdp1> νdp3
(9) -8.0 <fN / fm <-1.5
However,
f1: the focal length of the first lens group,
fn: focal length of the nth lens group (n is a positive integer of 4 or more),
fm: focal length of the m-th lens group (m is a positive integer of 3 or more),
νdp1: Abbe number for the d-line of the positive lens located closest to the object side among the positive lenses in the first lens group,
νdp2: Abbe number for the d-line of the positive lens located second from the object side among the positive lenses in the first lens group,
νdp3: Abbe number for the d-line of the positive lens located third from the object side among the positive lenses in the first lens group,
fN: the focal length of the lens unit having a negative refractive power located between the second lens unit and the nth lens unit,
It is.
In another aspect, the zoom lens system of the present invention includes, in order from the most object side, a first lens group having a positive refractive power and a second lens group having a negative refractive power, and is closest to the image side. Having an nth lens unit having a positive refractive power; the first lens unit and the nth lens unit are fixed with respect to the image plane during zooming from the short focal length end to the long focal length end The second lens group moves in the optical axis direction; the mth lens group having a positive refractive power is provided between the second lens group and the nth lens group; the second lens group and the second lens group a lens unit having a negative refractive power different from that of the m-th lens unit is provided between the n-th lens unit; And a positive lens having a convex surface facing the object side, a positive lens having a convex surface facing the object side, and a positive lens having a convex surface facing the object side. The negative refractive power lens group positioned between the second lens group and the nth lens group is composed of a negative single lens having a convex surface facing the image side; and the following conditional expression (1): , (2), (3), (10), and (11) are satisfied.
(1) 1.23 <f1 / fn <1.50
(2) 1.20 <fn / fm <1.60
(3) νdp2>νdp1> νdp3
(10) 1.55 <NdN <1.73
(11) 30 <νdN <60
However,
f1: the focal length of the first lens group,
fn: focal length of the nth lens group (n is a positive integer of 4 or more),
fm: focal length of the m-th lens group (m is a positive integer of 3 or more),
νdp1: Abbe number for the d-line of the positive lens located closest to the object side among the positive lenses in the first lens group,
νdp2: Abbe number for the d-line of the positive lens located second from the object side among the positive lenses in the first lens group,
νdp3: Abbe number for the d-line of the positive lens located third from the object side among the positive lenses in the first lens group,
NdN: a refractive index with respect to d line of a negative single lens constituting a lens unit having a negative refractive power located between the second lens unit and the nth lens unit,
νdN: Abbe number with respect to d-line of a negative single lens constituting a lens unit having a negative refractive power located between the second lens unit and the nth lens unit,
It is.

In the invention of the lens system, there are various definitions of “lens group” (what defines the lens group on the boundary).
The “group” in the expression “3 groups, 4 sheets” is a “group” defined with the air gap as a boundary. For example, a single lens is a “group” by itself, and when a plurality of lenses are cemented together (because there is no “air gap” between the plurality of lenses), the plurality of lenses become a “group”. . Accordingly, “four elements in three groups” means a lens system composed of a pair of cemented lenses obtained by cementing two lenses and two single lenses.
Next, in the expression “5-group zoom” (unless otherwise defined), the lens group is generally defined at a portion where the lens interval changes during zooming. The expression “lens group” in a single focus lens is not only defined when the lens group is defined by the part where the lens interval changes during focusing, but also when defined by the aperture or when the lens interval is the maximum part. Since there are cases where they are defined, some definition (the law of carving) is often made.
The “lens group” in the following specification is defined with a portion where the lens interval changes during zooming or a portion where the lens interval changes during focusing as a boundary. Therefore, as in the first embodiment of Patent Document 1, the lens interval d3 that does not change during zooming but changes during focusing is also a boundary that defines the “lens group” in this specification. The lens according to the first embodiment is defined as “5 group configuration” instead of “4 group configuration”.

  The zoom lens system of the present invention can have two or more lens groups including the mth lens group between the second lens group and the nth lens group.

Among the condition ranges defined by the conditional expression (5), it is preferable that the following conditional expression (5 ′) is satisfied.
(5 ′) νave> 72

Among the condition ranges defined by the conditional expression (6), it is preferable that the following conditional expression (6 ′) is satisfied.
(6 ′) 0.55 <DnP / LDn <0.75

Among the condition ranges defined by the conditional expression (9), it is preferable that the following conditional expression (9 ′) is satisfied.
(9 ′) − 4.0 <fN / fm <−1.5

  According to the present invention, it is possible to satisfactorily correct various aberrations such as spherical aberration, coma aberration, and distortion, and to suppress performance change (performance degradation) during focusing while using a focusing group with a small operation load. A zoom lens system is obtained.

It is a lens block diagram at the time of infinity focusing in the short focal distance end of Numerical Example 1 of the zoom lens system according to the present invention. FIG. 2 is a diagram illustrating various aberrations in the configuration of FIG. 1. FIG. 2 is a lateral aberration diagram in the configuration of FIG. 1. 6 is a lens configuration diagram at the time of infinity focusing at the long focal length end of the numerical example 1. FIG. FIG. 5 is a diagram illustrating various aberrations in the configuration of FIG. 4. FIG. 5 is a lateral aberration diagram in the configuration of FIG. 4. It is a lens block diagram at the time of infinity focusing in the short focal distance end of Numerical Example 2 of the zoom lens system by the present invention. FIG. 8 is a diagram illustrating various aberrations in the configuration of FIG. 7. FIG. 8 is a lateral aberration diagram in the configuration of FIG. 7. It is a lens block diagram at the time of infinity focusing in the long focal distance end of the numerical example 2; FIG. 11 is a diagram illustrating various aberrations in the configuration of FIG. 10. FIG. 11 is a lateral aberration diagram in the configuration of FIG. 10. It is a lens block diagram at the time of infinity focusing in the short focal distance end of Numerical Example 3 of the zoom lens system by the present invention. FIG. 14 is a diagram illustrating various aberrations in the configuration of FIG. 13. FIG. 14 is a lateral aberration diagram in the configuration of FIG. 13. It is a lens block diagram at the time of infinity focusing in the long focal distance end of the numerical example 3; FIG. 17 is a diagram of various aberrations in the configuration of FIG. 16. FIG. 17 is a lateral aberration diagram in the configuration of FIG. 16. It is a lens block diagram at the time of infinity focusing in the short focal distance end of Numerical Example 4 of the zoom lens system by the present invention. FIG. 20 is a diagram illustrating various aberrations in the configuration in FIG. 19. FIG. 20 is a lateral aberration diagram in the configuration of FIG. 19. It is a lens block diagram at the time of infinity focusing in the long focal distance end of the numerical example 4; FIG. 23 is a diagram of various aberrations in the configuration of FIG. 22. FIG. 23 is a lateral aberration diagram in the configuration of FIG. 22. It is a lens block diagram at the time of infinity focusing in the short focal distance end of Numerical Example 5 of the zoom lens system by the present invention. FIG. 26 is a diagram illustrating various aberrations in the configuration in FIG. 25. FIG. 26 is a lateral aberration diagram in the configuration of FIG. 25. It is a lens block diagram at the time of infinity focusing in the long focal distance end of the same numerical example 5. FIG. 29 is a diagram of various aberrations in the configuration of FIG. 28. FIG. 29 is a lateral aberration diagram in the configuration of FIG. 28. It is a lens block diagram at the time of infinity focusing in the short focal distance end of Numerical Example 6 of the zoom lens system by the present invention. FIG. 32 is a diagram of various aberrations in the configuration of FIG. 31. FIG. 32 is a lateral aberration diagram in the configuration of FIG. 31. It is a lens block diagram at the time of infinity focusing in the long focal distance end of the numerical example 6. FIG. 35 is a diagram showing various aberrations in the configuration of FIG. 34. FIG. 35 is a lateral aberration diagram in the configuration of FIG. 34. FIG. 3 is a first simplified movement diagram showing a zoom locus of a zoom lens system according to the present invention. It is a 2nd simple movement figure which shows the zoom locus | trajectory of the zoom lens system by this invention. It is a 3rd simple movement figure which shows the zoom locus | trajectory of the zoom lens system by this invention.

  The zoom lens system according to the present embodiment includes the “first embodiment” configured by Numerical Example 1-5 and the “second embodiment” configured by Numerical Example 6. Hereinafter, these “first embodiment” and “second embodiment” will be described in order.

“First Embodiment”
In Numerical Example 1-5, the zoom lens system of the present embodiment includes a first lens group G1 having a positive refractive power and a second lens having a negative refractive power, as shown in the simplified movement diagrams of FIGS. A lens group G2, a third lens group (m-th lens group) G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group (n-th lens group) having a positive refractive power. And G5. A stop S is located between the fourth lens group G4 and the fifth lens group G5 (immediately before the fifth lens group G5). I is the image plane.

In Numerical Example 1-4, the zoom lens system according to the present embodiment is, as shown in the simplified movement diagram of FIG. 37, the zoom lens system at the time of zooming from the short focal length end (Wide) to the long focal length end (Tele). The distance between the first lens group G1 and the second lens group G2 is increased, the distance between the second lens group G2 and the third lens group G3 is decreased, and the distance between the third lens group G3 and the fourth lens group G4 is increased. The distance between the fourth lens group G4 and the fifth lens group G5 decreases.
More specifically, at the time of zooming from the short focal length end to the long focal length end, the first lens group G1 is fixed with respect to the image plane I (does not move in the optical axis direction), and the second lens group. G2 to the fourth lens group G4 move monotonously to the image side, and the fifth lens group G5 is fixed with respect to the image plane I together with the stop S (does not move in the optical axis direction). The third lens group G3 may move once to the object side (image side) and then return to the image side (object side) (U-turn) upon zooming from the short focal length end to the long focal length end. Is possible.

In Numerical Example 5, in the zoom lens system according to the fifth embodiment, as shown in the simplified movement diagram of FIG. 38, the first lens is changed upon zooming from the short focal length end (Wide) to the long focal length end (Tele). The distance between the group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, and the distance between the third lens group G3 and the fourth lens group G4 does not change (constant). The distance between the fourth lens group G4 and the fifth lens group G5 decreases.
More specifically, at the time of zooming from the short focal length end to the long focal length end, the first lens group G1 is fixed with respect to the image plane I (does not move in the optical axis direction), and the second lens group. G2 to the fourth lens group G4 move monotonously to the image side, and the fifth lens group G5 is fixed with respect to the image plane I together with the stop S (does not move in the optical axis direction). The third lens group G3 and the fourth lens group G4 once move to the object side (image side) and then return to the image side (object side) upon zooming from the short focal length end to the long focal length end ( U-turn) is also possible. When the fourth lens group G4 makes a U-turn, the distance between the fourth lens group G4 and the fifth lens group G5 increases in the vicinity of the long focal length end when zooming from the short focal length end to the long focal length end. May be.

  In Numerical Example 1-5, the zoom lens system according to the present embodiment forms an image of the third lens group (m-th lens group) G3 as a focus lens group as shown in the simplified movement diagrams of FIGS. Focusing is done by moving to the side. Therefore, in Numerical Example 5, the distance between the third lens group G3 and the fourth lens group G4 is constant during zooming, but the distance between the third lens group G3 and the fourth lens group G4 changes during focusing. In the document, the third lens group G3 and the fourth lens group G4 are defined as separate “lens groups” and counted.

  The first lens group G1 includes, in order from the object side, a negative lens (a negative lens having a concave surface on the image side) 11, a positive lens (a positive lens having a convex surface on the object side) 12, and a positive lens (to the object side). A positive lens 13 having a convex surface and a positive lens 14 (a positive lens having a convex surface facing the object side). The negative lens 11 and the positive lens 12 are not joined in Numerical Example 1-2, but are joined in Numerical Example 3-5.

  The second lens group G2 includes a positive lens 21, a negative lens 22, a negative lens 23, a positive lens 24, and a negative lens 25 in order from the object side. The positive lens 21 and the negative lens 22 are cemented, and the negative lens 23 and the positive lens 24 are cemented.

  The third lens group G3 includes a positive lens 31, a positive lens 32, and a negative lens 33 in order from the object side. The positive lens 32 and the negative lens 33 are cemented.

  The fourth lens group G4 is composed of a negative single lens (negative single lens with a convex surface facing the image side) 41.

  The fifth lens group G5 includes, in order from the object side, a positive lens 51, a positive lens 52, a negative lens 53, a positive lens (intermediate positive lens) 54, a negative lens 55, and a positive lens 56.

“Second Embodiment”
In Numerical Example 6, the zoom lens system according to the present embodiment includes a first lens group G1 ′ having a positive refractive power and a first lens having a negative refractive power in order from the object side, as shown in the simplified movement diagram of FIG. A second lens group G2 ′, a third lens group G3 ′ having a negative refractive power, a fourth lens group (m-th lens group) G4 ′ having a positive refractive power, and a fifth lens group having a positive refractive power (first lens group). n lens group) G5 ′. A diaphragm S is located between the fourth lens group G4 ′ and the fifth lens group G5 ′ (immediately before the fifth lens group G5 ′). The diaphragm S is located between the short focal length end and the long focal length end. At the time of zooming, it is fixed with respect to the image plane I together with the fifth lens group G5 ′ (does not move in the optical axis direction).

In Numerical Example 6, the zoom lens system according to the present embodiment, as shown in the simplified movement diagram of FIG. 39, the first lens at the time of zooming from the short focal length end (Wide) to the long focal length end (Tele). The distance between the group G1 ′ and the second lens group G2 ′ increases, the distance between the second lens group G2 ′ and the third lens group G3 ′ decreases, and the distance between the third lens group G3 ′ and the fourth lens group G4 ′. Decreases, and the distance between the fourth lens group G4 ′ and the fifth lens group G5 ′ decreases.
More specifically, during zooming from the short focal length end to the long focal length end, the first lens group G1 ′ is fixed with respect to the image plane I (does not move in the optical axis direction), and the second lens The group G2 ′ to the fourth lens group G4 ′ move monotonously to the image side, and the fifth lens group G5 ′ is fixed with respect to the image plane I together with the stop S (does not move in the optical axis direction).

  In Numerical Example 6, in the zoom lens system of the present embodiment, as shown in the simplified movement diagram of FIG. 39, the fourth lens group (mth lens group) G4 ′ is used as a focus lens group and moved to the image side. Focusing is done.

  The first lens group G1 ′ includes, in order from the object side, a negative lens (a negative lens having a concave surface facing the image side) 11 ′, a positive lens (a positive lens having a convex surface facing the object side) 12 ′, and a positive lens ( It consists of a positive lens (convex surface facing the object side) 13 'and a positive lens (positive lens having a convex surface facing the object side) 14'. The negative lens 11 'and the positive lens 12' are cemented.

  The second lens group G2 'includes a positive lens 21' and a negative lens 22 'in order from the object side. The positive lens 21 'and the negative lens 22' are cemented.

  The third lens group G3 'includes, in order from the object side, a negative lens 31', positive lenses 32 and ', and a negative lens 33'. The negative lens 31 'and the positive lens 32' are cemented.

  The fourth lens group G4 'includes, in order from the object side, a positive lens 41', a positive lens 42 ', and a negative lens 43'. The positive lens 42 'and the negative lens 43' are cemented.

  The fifth lens group G5 ′ includes, in order from the object side, a positive lens 51 ′, a positive lens 52 ′, a negative lens 53 ′, a positive lens 54 ′, a negative lens 55 ′, and a positive lens (intermediate positive lens). 56 ′, a negative lens 57 ′, and a positive lens 58 ′. The negative lens 53 'and the positive lens 54' are cemented.

  The zoom lens system of the present embodiment adopts a positive / negative / positive / negative 5 group lens configuration or a positive / negative / positive / positive 5 group lens configuration, and optimally sets the power ratio (power balance) of each lens group, While successfully correcting various aberrations such as spherical aberration, coma aberration, distortion aberration, etc., it succeeded in suppressing performance change (performance degradation) during focusing.

Conditional expression (1) defines the power ratio (power balance) between the first lens group (G1 or G1 ′) and the lens group having the positive refractive power closest to the image, which is the nth lens group. By satisfying conditional expression (1), spherical aberration, coma aberration, and distortion aberration can be corrected satisfactorily.
If the upper limit of conditional expression (1) is exceeded, the power of the nth lens group becomes too strong, making it difficult to correct spherical aberration and coma over the entire zoom range.
If the lower limit of conditional expression (1) is exceeded, the power of the first lens group will be too strong, resulting in large distortion.

Conditional expression (2) indicates that the nth lens group having the positive refractive power closest to the image side and the mth lens group which is the focus lens group (a lens having a positive refractive power between the second lens group and the nth lens group). Group) power ratio (power balance). By satisfying conditional expression (2), it is possible to correct spherical aberration and coma well, and to suppress performance change (performance degradation) during focusing.
If the upper limit of conditional expression (2) is exceeded, the power of the mth lens group, which is the focus lens group, becomes too strong, and the performance change (performance degradation) during focusing becomes large.
If the lower limit of conditional expression (2) is exceeded, the power of the nth lens group becomes too strong, and it becomes difficult to correct spherical aberration and coma over the entire zoom range.

  Conditional expression (3) defines the magnitude relationship of the Abbe number with respect to the d-line of the three positive lenses in the first lens group (G1 or G1 '). In order to correct chromatic aberration (particularly lateral chromatic aberration at the end of the long focal length), it is preferable to use a so-called low dispersion material having a large Abbe number for the d-line for the positive lens in the first lens group (G1 or G1 '). However, since a low dispersion material generally has a low refractive index, it is disadvantageous for correction of spherical aberration, coma aberration, and the like. In the zoom lens system of the present embodiment, the magnitude relation of the Abbe number with respect to the d-line of the three positive lenses in the first lens group (G1 or G1 ′) is set so as to satisfy the conditional expression (3). Thus, correction of chromatic aberration, spherical aberration, and coma aberration can be made compatible. If the conditional expression (3) is not satisfied, correction of chromatic aberration, spherical aberration, and coma aberration cannot be achieved at the same time.

  Conditional expression (4) defines a difference in refractive index with respect to the d-line between the positive lens located closest to the object side in the n-th lens group and the positive lens located second from the object side. Since the positive lens located closest to the object side in the nth lens group is an important lens that is directly linked to the correction of spherical aberration, it is preferably formed from a material having a high refractive index. Further, the positive lens located second from the object side in the nth lens group can suppress the occurrence of spherical aberration by making it a shape close to an aplanatic lens. That is, spherical aberration can be corrected satisfactorily by satisfying conditional expression (4). If conditional expression (4) is not satisfied, the effect of correcting spherical aberration will be insufficient.

  Conditional expression (5) and conditional expression (5 ′) define the average value of the Abbe number for the d-line of the positive lens located closest to the object side in the nth lens group and the positive lens located second from the object side. doing. Since these two positive lenses are both important for correcting chromatic aberration, the Abbe number with respect to the d-line should be as large as possible. That is, chromatic aberration can be favorably corrected by satisfying conditional expression (5), and further, the effect of correcting chromatic aberration can be enhanced by satisfying conditional expression (5 ′). If conditional expression (5) is not satisfied, the effect of correcting chromatic aberration will be insufficient.

  In Numerical Example 1-5, the zoom lens system according to the present embodiment includes a conditional expression between the positive lens 51 positioned closest to the object side and the positive lens 56 positioned closest to the image side in the fifth lens group G5. An intermediate positive lens 54 that satisfies (6), conditional expression (7), and conditional expression (8) is provided. Thereby, coma aberration, chromatic aberration, and field curvature can be effectively corrected with a small lens configuration.

  In Numerical Example 6, the zoom lens system according to the present embodiment has a condition between the positive lens 51 ′ positioned closest to the object side in the fifth lens group G5 ′ and the positive lens 58 ′ positioned closest to the image side. An intermediate positive lens 56 ′ that satisfies Expression (6), Conditional Expression (7), and Conditional Expression (8) is provided. Thereby, coma aberration, chromatic aberration, and field curvature can be effectively corrected with a small lens configuration.

  In the zoom lens system of the present embodiment, the second lens group (G2 or G2 ′) having a negative refractive power functions as a variable power lens group having a main variable power action, and the second lens group (G2 or G2 or G2 ′). In addition to G2 ′), by providing a lens unit having a negative refractive power (fourth lens group G4 or third lens group G3 ′), aberration variations during zooming and focusing can be more effectively corrected. it can. As described above, the fourth lens group G4 includes the negative single lens (negative single lens with a convex surface facing the image side) 41 in Numerical Example 1-5.

  Conditional expression (9) and conditional expression (9 ′) are expressed in terms of a negative refractive power lens group (fourth lens group G4 or third lens group G3 ′) and an mth lens group (third lens group) which is a focus lens group. G3 or the fourth lens group G4 ′) defines the power ratio (power balance). By satisfying conditional expression (9), it is possible to satisfactorily correct variations in field curvature during zooming and focusing. By satisfying conditional expression (9 ′), images during zooming and focusing can be corrected. Variations in surface curvature can be corrected even better. If the conditional expression (9) is not satisfied, correction of the curvature of field curvature during zooming and focusing will be insufficient.

  Conditional expression (10) defines the refractive index for the d-line of the negative single lens 41 constituting the fourth lens group G4, and conditional expression (11) represents the negative single lens 41 constituting the fourth lens group G4. Defines the Abbe number for the d-line. By satisfying conditional expression (10) and conditional expression (11), it is possible to effectively correct chromatic aberration and coma aberration after the fourth lens group G4 is configured with the minimum number of lenses (one). If conditional expression (10) and conditional expression (11) are not satisfied, the correction effect of chromatic aberration and coma aberration will be insufficient.

Next, specific numerical examples 1-6 will be described. In the various aberration diagrams and lateral aberration diagrams and tables, d-line, g-line and C-line are aberrations for each wavelength, S is sagittal, M is meridional, FNO. Is F-number, f is the focal length of the whole system, W Is half angle of view (°), Y is image height, fB Is the back focus, L is the total lens length, R is the radius of curvature, d is the lens thickness or lens spacing, N (d) is the refractive index for the d-line, and ν (d) is the Abbe number for the d-line. The f-number, focal length, half angle of view, image height, back focus, total lens length, and lens interval d that changes with zooming are shown in the order of short focal length end-intermediate focal length-long focal length end. Yes. The unit of length is [mm]. In all numerical examples 1-6, no aspheric lens is used.

[Numerical Example 1]
1 to 6 and Tables 1 to 3 show Numerical Example 1 of the zoom lens system according to the present invention. FIG. 1 is a lens configuration diagram at the time of focusing at infinity at the short focal length end, FIG. 2 is a diagram of various aberrations, FIG. 3 is a diagram of its lateral aberration, and FIG. 4 is a graph at the time of focusing at infinity at the long focal length end. FIG. 5 is a diagram showing various aberrations, and FIG. 6 is a diagram showing lateral aberrations. Table 1 shows surface data, Table 2 shows various data, and Table 3 shows zoom lens group data.

  The zoom lens system according to Numerical Example 1 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group having a positive refractive power ( The mth lens group and the focus lens group) G3, the fourth lens group G4 having a negative refractive power, and the fifth lens group (nth lens group) G5 having a positive refractive power. A stop S is located between the fourth lens group G4 and the fifth lens group G5 (immediately before the fifth lens group G5). The stop S changes from a short focal length end to a long focal length end. At the time of magnification, it is fixed with respect to the image plane I together with the fifth lens group G5 (does not move in the optical axis direction).

  The first lens group G1 includes, in order from the object side, a negative meniscus lens that is convex on the object side (a negative lens having a concave surface on the image side) 11 and a positive meniscus lens that is convex on the object side (a convex surface on the object side). A positive lens 12, a biconvex positive lens (a positive lens having a convex surface facing the object side) 13, and a positive meniscus lens 14 (a positive lens having a convex surface facing the object side) 14.

  The second lens group G2 includes, in order from the object side, a positive meniscus lens 21 convex to the image side, a biconcave negative lens 22, a biconcave negative lens 23, a biconvex positive lens 24, and a biconcave negative lens 25. Consists of. The positive meniscus lens 21 and the biconcave negative lens 22 are cemented, and the biconcave negative lens 23 and the biconvex positive lens 24 are cemented.

  The third lens group G3 includes, in order from the object side, a biconvex positive lens 31, a biconvex positive lens 32, and a negative meniscus lens 33 convex on the image side. The biconvex positive lens 32 and the negative meniscus lens 33 are cemented.

  The fourth lens group G4 includes a negative meniscus single lens 41 (a negative single lens having a convex surface facing the image side) 41 convex toward the image side.

  The fifth lens group G5 includes, in order from the object side, a biconvex positive lens 51, a positive meniscus lens 52 convex to the object side, a biconcave negative lens 53, a biconvex positive lens (intermediate positive lens) 54, and an image. It consists of a negative meniscus lens 55 convex on the side and a positive meniscus lens 56 convex on the image side.

(Table 1)
Surface data surface number R d N (d) ν (d)
1 268.211 2.10 1.83400 37.2
2 77.688 0.20
3 78.470 9.10 1.49700 81.6
4 300.000 0.50
5 92.628 11.70 1.43875 95.0
6 -276.712 0.20
7 91.695 7.30 1.59522 67.7
8 398.949 d8
9 -533.916 5.10 1.91650 31.6
10 -61.110 1.40 1.81600 46.6
11 61.110 5.40
12 -109.774 1.30 1.59522 67.7
13 46.933 7.00 1.80518 25.4
14 -254.300 2.20
15 -72.191 1.10 1.83481 42.7
16 170.851 d16
17 153.851 6.50 1.80 400 46.6
18 -72.797 0.20
19 428.584 7.30 1.49700 81.6
20 -49.133 1.40 1.84666 23.8
21 -119.634 d21
22 -72.589 1.50 1.61272 58.7
23 -4319.637 d23
24 stops ∞ 1.20
25 32.920 8.20 1.59522 67.7
26 -264.639 0.10
27 35.157 4.50 1.43875 95.0
28 90.333 2.10
29 -193.592 1.30 1.78590 44.2
30 37.027 17.40
31 83.055 6.00 1.59522 67.7
32 -83.055 9.00
33 -25.707 1.30 1.81600 46.6
34 -91.405 0.20
35 -274.911 3.60 1.91650 31.6
36 -62.715-
(Table 2)
Various data zoom ratio (magnification ratio) 2.69
Short focal length end Intermediate focal length Long focal length end
FNO. 2.9 2.9 2.9
f 72.10 100.00 194.00
W 17.1 12.2 6.2
Y 21.64 21.64 21.64
fB 40.00 40.00 40.00
L 245.45 245.45 245.45
d8 3.48 19.67 40.33
d16 26.77 21.33 4.00
d21 9.22 11.87 25.20
d23 31.86 18.45 1.80
(Table 3)
Lens group data group Start surface Focal length
1 1 118.56
2 9 -33.16
3 17 58.47
4 22 -120.51
5 25 81.79

[Numerical Example 2]
7 to 12 and Tables 4 to 6 show Numerical Example 2 of the zoom lens system according to the present invention. FIG. 7 is a lens configuration diagram at the time of focusing at infinity at the short focal length end, FIG. 8 is a diagram of various aberrations thereof, FIG. 9 is a lateral aberration diagram thereof, and FIG. 10 is a graph at the time of focusing at infinity at the long focal length end. FIG. 11 is a diagram showing various aberrations, and FIG. 12 is a diagram showing lateral aberrations. Table 4 shows surface data, Table 5 shows various data, and Table 6 shows zoom lens group data.

The lens configuration of Numerical Example 2 is the same as the lens configuration of Numerical Example 1 except for the following points.
(1) The negative single lens 41 of the fourth lens group G4 is a biconcave negative single lens.

(Table 4)
Surface data surface number R d N (d) ν (d)
1 309.600 2.10 1.80610 33.3
2 85.789 0.20
3 85.437 9.00 1.49700 81.6
4 300.000 0.50
5 109.735 10.40 1.43500 95.0
6 -324.713 0.20
7 89.923 7.40 1.59282 68.6
8 488.290 d8
9 -515.875 5.20 1.90366 31.3
10 -57.732 1.40 1.81600 46.6
11 57.732 5.30
12 -129.592 1.30 1.59282 68.6
13 45.337 7.10 1.80518 25.5
14 -233.290 2.50
15 -64.471 1.10 1.83481 42.7
16 221.827 d16
17 188.650 6.40 1.80420 46.5
18 -74.390 0.20
19 200.572 7.80 1.49700 81.6
20 -51.664 1.30 1.84666 23.8
21 -113.738 d21
22 -88.301 1.50 1.65412 39.6
23 735.519 d23
24 stops ∞ 1.20
25 33.382 7.80 1.59282 68.6
26 -442.682 0.40
27 34.135 4.20 1.43500 95.0
28 68.371 2.20
29 -227.525 1.30 1.77250 49.6
30 34.854 14.90
31 78.662 6.40 1.59282 68.6
32 -78.662 13.20
33 -27.032 1.30 1.80420 46.5
34 -65.193 0.20
35 -157.501 3.60 1.90366 31.3
36 -69.337-
(Table 5)
Various data zoom ratio (magnification ratio) 2.69
Short focal length end Intermediate focal length Long focal length end
FNO. 2.9 2.9 2.9
f 72.01 100.00 194.00
W 17.1 12.2 6.2
Y 22.64 21.64 21.64
fB 37.80 37.80 37.80
L 249.30 249.30 249.30
d8 3.33 20.39 42.38
d16 26.13 20.55 4.00
d21 8.60 12.46 26.71
d23 36.84 21.50 1.80
(Table 6)
Lens group data group Start surface Focal length
1 1 123.42
2 9 -33.31
3 17 55.91
4 22 -120.44
5 25 87.16

[Numerical Example 3]
13 to 18 and Tables 7 to 9 show Numerical Example 3 of the zoom lens system according to the present invention. FIG. 13 is a lens configuration diagram at the time of focusing at infinity at the short focal length end, FIG. 14 is a diagram showing various aberrations thereof, FIG. 15 is a lateral aberration diagram thereof, and FIG. FIG. 17 is a diagram showing various aberrations, and FIG. 18 is a diagram showing its lateral aberration. Table 7 shows surface data, Table 8 shows various data, and Table 9 shows zoom lens group data.

The lens configuration of Numerical Example 3 is the same as the lens configuration of Numerical Example 1 except for the following points.
(1) The negative meniscus lens 11 and the positive meniscus lens 12 of the first lens group G1 are cemented.
(2) The positive lens 32 of the third lens group G3 is a positive meniscus lens convex on the image side.

(Table 7)
Surface data surface number R d N (d) ν (d)
1 298.927 2.30 1.83400 37.2
2 83.202 8.48 1.49700 81.6
3 314.408 0.50
4 99.969 11.13 1.43875 95.0
5 -278.717 0.20
6 86.058 7.57 1.59522 67.7
7 338.946 d7
8 -820.899 4.99 1.90366 31.3
9 -59.351 1.20 1.81600 46.6
10 58.207 4.98
11 -125.863 1.33 1.59522 67.7
12 47.206 6.16 1.80518 25.5
13 -316.015 2.47
14 -63.999 1.10 1.83481 42.7
15 217.234 d15
16 182.634 5.83 1.80 400 46.6
17 -66.021 0.20
18 -195.611 5.35 1.49700 81.6
19 -46.988 1.30 1.84666 23.8
20 -96.235 d20
21 -56.165 1.40 1.61340 44.3
22 -102.414 d22
23 stop ∞ 1.20
24 35.843 8.25 1.59522 67.7
25 -1114.899 2.65
26 33.094 4.97 1.43875 95.0
27 101.917 1.75
28 -407.374 1.30 1.78590 44.2
29 32.342 14.77
30 84.103 5.95 1.59522 67.7
31 -84.103 11.77
32 -29.143 1.30 1.81600 46.6
33 -108.062 0.20
34 -341.779 3.47 1.90366 31.3
35 -67.612-
(Table 8)
Various data zoom ratio (magnification ratio) 2.69
Short focal length end Intermediate focal length Long focal length end
FNO. 2.9 2.9 2.9
f 72.06 100.00 194.00
W 17.2 12.2 6.2
Y 21.64 21.64 21.64
fB 37.79 37.79 37.79
L 243.06 243.05 243.06
d7 3.30 20.97 43.94
d15 27.09 21.74 4.00
d20 8.58 10.89 20.96
d22 31.73 17.09 1.80
(Table 9)
Lens group data group Start surface Focal length
1 1 119.85
2 8 -32.59
3 16 66.08
4 21 -205.12
5 24 90.93

[Numerical Example 4]
19 to 24 and Tables 10 to 12 show Numerical Example 4 of the zoom lens system according to the present invention. 19 is a lens configuration diagram at the time of focusing at infinity at the short focal length end, FIG. 20 is a diagram showing various aberrations, FIG. 21 is a lateral aberration diagram, and FIG. 22 is a diagram at the time of focusing at infinity at the long focal length end. FIG. 23 is a diagram showing various lens aberrations, and FIG. 24 is a diagram showing lateral aberrations. Table 10 shows surface data, Table 11 shows various data, and Table 12 shows zoom lens group data.

The lens configuration of Numerical Example 4 is the same as the lens configuration of Numerical Example 1 except for the following points.
(1) The negative meniscus lens 11 and the positive meniscus lens 12 of the first lens group G1 are cemented.
(2) The positive lens 24 of the second lens group G2 is a positive meniscus lens convex toward the object side.
(3) The positive lens 32 of the third lens group G3 is a positive meniscus lens convex on the image side.
(4) The positive lens 56 of the fifth lens group G5 is a biconvex positive lens.

(Table 10)
Surface data surface number R d N (d) ν (d)
1 1052.998 2.90 1.72047 34.7
2 88.327 9.51 1.49700 81.6
3 431.124 2.03
4 137.001 9.16 1.49782 82.6
5 -281.758 0.20
6 88.569 8.22 1.61800 63.4
7 636.494 d7
8 -651.050 6.07 1.83400 37.2
9 -49.578 1.30 1.77250 49.6
10 61.763 4.69
11 -241.851 1.30 1.61800 63.4
12 39.859 6.66 1.80518 25.4
13 1735.761 3.12
14 -66.909 1.30 1.80610 40.9
15 161.538 d15
16 203.183 5.49 1.80 400 46.6
17 -78.090 0.11
18 -489.495 5.85 1.49700 81.6
19 -50.693 1.30 1.84666 23.8
20 -89.448 d20
21 -71.279 1.70 1.71700 47.9
22 -143.847 d22
23 stop ∞ 0.00
24 40.535 7.07 1.61800 63.4
25 -385.374 0.10
26 42.343 5.48 1.49700 81.6
27 103.873 1.77
28 -407.896 1.40 1.72342 38.0
29 41.410 29.47
30 96.293 4.27 1.59522 67.7
31 -99.999 7.27
32 -33.048 1.20 1.80 400 46.6
33 -100.848 0.20
34 188.052 3.56 1.80518 25.4
35 -645.973-
(Table 11)
Various data zoom ratio (magnification ratio) 2.69
Short focal length end Intermediate focal length Long focal length end
FNO. 2.9 2.9 2.9
f 72.10 100.00 194.00
W 17.2 12.2 6.2
Y 21.64 21.64 21.64
fB 37.45 37.45 37.45
L 241.26 241.26 241.26
d7 2.50 19.58 41.66
d15 26.74 20.91 2.00
d20 5.31 7.99 18.46
d22 30.57 16.63 3.00
(Table 12)
Lens group data group Start surface Focal length
1 1 116.27
2 8 -32.88
3 16 64.58
4 21 -199.00
5 24 93.00

[Numerical Example 5]
25 to 30 and Tables 13 to 15 show Numerical Example 5 of the zoom lens system according to the present invention. FIG. 25 is a lens configuration diagram at the time of focusing at infinity at the short focal length end, FIG. 26 is a diagram of various aberrations thereof, FIG. 27 is a diagram of its lateral aberration, and FIG. FIG. 29 is a diagram showing various aberrations, and FIG. 30 is a diagram showing its lateral aberration. Table 13 shows surface data, Table 14 shows various data, and Table 15 shows zoom lens group data.

The lens configuration of Numerical Example 5 is the same as the lens configuration of Numerical Example 1 except for the following points.
(1) The negative meniscus lens 11 and the positive meniscus lens 12 of the first lens group G1 are cemented.
(2) The positive lens 24 of the second lens group G2 is a positive meniscus lens convex toward the object side.
(3) The positive lens 56 of the fifth lens group G5 is a biconvex positive lens.

(Table 13)
Surface data surface number R d N (d) ν (d)
1 702.779 3.00 1.72342 38.0
2 91.358 10.16 1.49700 81.6
3 1501.767 2.66
4 122.662 8.62 1.49782 82.6
5 -465.130 0.20
6 129.226 6.22 1.61800 63.4
7 826.842 d7
8 -391.287 5.38 1.83400 37.2
9 -43.814 1.30 1.77410 47.3
10 70.787 3.11
11 -253.410 1.30 1.61800 63.4
12 38.650 5.37 1.80518 25.4
13 286.481 3.12
14 -68.554 1.30 1.80 400 46.6
15 160.382 d15
16 309.125 4.25 1.72900 54.6
17 -109.742 0.10
18 1760.334 6.46 1.49700 81.6
19 -44.675 1.30 1.90400 27.2
20 -65.041 d20
21 -66.044 1.49 1.70000 44.2
22 -80.490 d22
23 stop ∞ 0.00
24 42.674 6.97 1.61800 63.4
25 -776.064 0.10
26 41.881 5.88 1.49700 81.6
27 104.211 1.62
28 -723.179 1.40 1.69000 35.1
29 43.912 32.21
30 102.186 4.27 1.61800 63.4
31 -134.020 9.29
32 -31.937 1.20 1.80 400 46.6
33 -96.796 0.20
34 144.464 5.40 1.77742 26.8
35 -1415.259-
(Table 14)
Various data zoom ratio (magnification ratio) 2.69
Short focal length end Intermediate focal length Long focal length end
FNO. 2.9 2.9 2.9
f 72.11 119.99 194.00
W 17.1 10.1 6.2
Y 21.64 21.64 21.64
fB 38.05 38.05 38.06
L 249.32 249.32 249.32
d7 2.40 34.74 54.80
d15 20.25 13.38 2.00
d20 14.04 14.04 14.04
d22 37.20 11.74 3.04
(Table 15)
Lens group data group Start surface Focal length
1 1 134.15
2 8 -32.16
3 16 72.45
4 21 -549.02
5 24 92.52

[Numerical Example 6]
FIGS. 31 to 36 and Tables 16 to 18 show Numerical Example 6 of the zoom lens system according to the present invention. FIG. 31 is a lens configuration diagram at the time of focusing at infinity at the short focal length end, FIG. 32 is a diagram of various aberrations thereof, FIG. 33 is a diagram of its lateral aberration, and FIG. 34 is a graph at the time of focusing at infinity at the long focal length end. FIG. 35 is a diagram showing various aberrations, and FIG. 36 is a lateral aberration diagram. Table 16 shows surface data, Table 17 shows various data, and Table 18 shows zoom lens group data.

  The zoom lens system according to Numerical Example 6 includes, in order from the object side, a first lens group G1 ′ having a positive refractive power, a second lens group G2 ′ having a negative refractive power, and a third lens having a negative refractive power. It comprises a group G3 ′, a fourth lens group (m-th lens group, focus lens group) G4 ′ having a positive refractive power, and a fifth lens group (n-th lens group) G5 ′ having a positive refractive power. Yes. A diaphragm S is located between the fourth lens group G4 ′ and the fifth lens group G5 ′ (immediately before the fifth lens group G5 ′). The diaphragm S is located between the short focal length end and the long focal length end. At the time of zooming, it is fixed with respect to the image plane I together with the fifth lens group G5 ′ (does not move in the optical axis direction).

  The first lens group G1 ′ includes, in order from the object side, a negative meniscus lens that is convex toward the object side (a negative lens having a concave surface toward the image side) 11 ′ and a positive meniscus lens that is convex toward the object side (a convex surface toward the object side). A positive meniscus lens 12 ′, a positive meniscus lens convex toward the object side (a positive lens having a convex surface directed toward the object side), and a biconvex positive lens (a positive lens having a convex surface directed toward the object side) 14 ′ Consists of. The negative meniscus lens 11 'and the positive meniscus lens 12' are cemented.

  The second lens group G2 'includes, in order from the object side, a positive meniscus lens 21' convex to the image side and a biconcave negative lens 22 '. The positive meniscus lens 21 'and the biconcave negative lens 22' are cemented.

  The third lens group G3 'includes, in order from the object side, a biconcave negative lens 31', positive meniscus lenses 32 and 'convex to the object side, and a biconcave negative lens 33'. The biconcave negative lens 31 'and the positive meniscus lens 32' are cemented.

  The fourth lens group G4 'includes, in order from the object side, a positive meniscus lens 41' convex toward the image side, a biconvex positive lens 42 ', and a negative meniscus lens 43' convex toward the image side. The biconvex positive lens 42 'and the negative meniscus lens 43' are cemented.

  The fifth lens group G5 ′ includes, in order from the object side, a biconvex positive lens 51 ′, a positive meniscus lens 52 ′ convex to the object side, a biconcave negative lens 53 ′, and a positive meniscus lens 54 convex to the object side. ', A negative meniscus lens 55' convex toward the object side, a biconvex positive lens (intermediate positive lens) 56 ', a negative meniscus lens 57' convex toward the image side, and a biconvex positive lens 58 '. The biconcave negative lens 53 'and the positive meniscus lens 54' are cemented.

(Table 16)
Surface data surface number R d N (d) ν (d)
1 133.848 2.00 1.90366 31.3
2 79.909 9.41 1.45860 90.2
3 3114.867 0.20
4 109.975 4.43 1.43500 95.0
5 191.579 0.20
6 92.154 8.20 1.49700 81.6
7 -1154.616 d7
8 -829.746 4.37 1.90366 31.3
9 -68.784 1.50 1.69680 55.5
10 44.320 d10
11 -182.000 1.30 1.61800 63.4
12 41.115 5.50 1.80518 25.5
13 589.240 3.55
14 -46.524 1.30 1.83481 42.7
15 3900.032 d15
16 -196.945 3.80 1.77250 49.6
17 -72.511 0.20
18 88.995 8.01 1.49700 81.6
19 -41.287 1.30 1.74950 35.0
20 -107.447 d20
21 stop ∞ 2.00
22 37.347 8.23 1.72916 54.7
23 -234.037 0.20
24 35.757 4.82 1.49700 81.6
25 150.186 1.57
26 -192.330 1.50 1.83481 42.7
27 21.453 8.35 1.49700 81.6
28 52.800 2.35
29 192.600 1.10 1.62374 47.0
30 34.702 2.54
31 93.311 6.00 1.59349 67.0
32 -88.797 18.51
33 -34.234 1.30 1.90366 31.3
34 -68.531 0.20
35 240.131 4.05 1.84666 23.8
36 -84.437-
(Table 17)
Various data zoom ratio (magnification ratio) 2.69
Short focal length end Intermediate focal length Long focal length end
FNO. 2.9 2.9 2.9
f 72.10 117.92 194.00
W 16.8 10.2 6.2
Y 21.64 21.64 21.64
fB 38.53 38.53 38.53
L 228.56 228.56 228.54
d7 2.20 27.42 44.69
d10 15.12 8.39 6.19
d15 18.62 12.63 1.50
d20 29.10 16.60 12.65
(Table 18)
Lens group data group Start surface Focal length
1 1 119.13
2 8 -72.42
3 11 -54.49
4 16 75.65
5 22 93.80

Table 19 shows values for the conditional expressions of the numerical examples. In Numerical Example 6, since the premised lens configuration is different, the corresponding numerical values of the conditional expressions (9) to (11) cannot be calculated.
(Table 19)
Example 1 Example 2 Example 3
Conditional expression (1) 1.450 1.416 1.318
Conditional expression (2) 1.399 1.559 1.376
Conditional expression (3)
νdp1 81.55 81.61 81.55
νdp2 94.94 95.00 94.94
νdp3 67.73 68.62 67.73
Conditional expression (4) 0.157 0.158 0.156
Conditional expression (5) 81.34 81.81 81.34
Conditional expression (6) 0.626 0.555 0.597
Conditional expression (7) 1.156 1.294 1.270
Conditional expression (8) 67.73 68.62 67.73
Conditional expression (9) -2.061 -2.154 -3.104
Conditional expression (10) 1.613 1.654 1.613
Conditional expression (11) 58.72 39.62 44.27
Example 4 Example 5 Example 6
Conditional expression (1) 1.250 1.450 1.270
Conditional expression (2) 1.440 1.277 1.240
Conditional expression (3)
νdp1 81.55 81.55 90.19
νdp2 82.57 82.57 95.00
νdp3 63.33 63.33 81.61
Conditional expression (4) 0.121 0.121 0.232
Conditional expression (5) 72.44 72.44 68.14
Conditional expression (6) 0.733 0.703 0.505
Conditional expression (7) 1.119 0.979 1.209
Conditional expression (8) 67.73 63.33 67.00
Conditional expression (9) -3.081 -7.578 ***
Conditional expression (10) 1.717 1.700 ***
Conditional expression (11) 47.93 44.25 ***

  As apparent from Table 19, Numerical Example 1 to Numerical Example 5 satisfy the conditional expressions (1) to (11), and Numerical Example 6 represents the conditional expressions (1) to (11). Satisfies (8). Further, as is apparent from the various aberration diagrams and lateral aberration diagrams, the various aberrations and lateral aberration are corrected relatively well.

In the above embodiments (numerical examples), a zoom lens system having a positive / negative / positive / positive five-group lens configuration and a zoom lens system having a positive / negative / negative positive / positive five-group lens configuration are taken, and the former is the third lens group G3. And the fifth lens group G5 are “m-th lens group” and “n-th lens group”. In the latter case, the fourth lens group G4 ′ and the fifth lens group G5 ′ are “m-th lens group” and “n-th lens group”. ”Was described as an example.
However, the zoom lens system of the present invention can be applied to any zoom lens system having the following preconditions, and can be interpreted with its right range expanded.
(1) In order from the most object side, a first lens unit having a positive refractive power and a second lens group having a negative refractive power, and an nth lens group having a positive refractive power closest to the image side. Have.
(2) During zooming from the short focal length end to the long focal length end, the first lens group and the nth lens group are fixed with respect to the image plane, and the second lens group moves in the optical axis direction.
(3) An m-th lens group having a positive refractive power is provided between the second lens group and the n-th lens group.

  As described above, in the present specification, the “m-th lens group” means a lens group that is a unit of the focus lens group that moves during focusing. For this reason, how the “m-th lens group” behaves at the time of zooming from the short focal length end to the long focal length end (for example, moving alone or together with other lens groups in the optical axis direction or image). Whether it is fixed to the surface, etc.) has nothing to do with the definition of “m-th lens group” (separation from other lens groups).

  As described above, the zoom lens system according to the present invention can take, for example, a positive / negative / positive / negative five-group lens configuration or a positive / negative / positive / positive five-group lens configuration.

When the zoom lens system of the present invention is rewritten in a form that clarifies the aspect of the positive, negative, positive, and positive five-group lens configuration without using the expressions “m-th lens group” and “n-th lens group”, It becomes like this.
That is, the zoom lens system of this aspect includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a negative lens power. A fourth lens group having a refractive power and a fifth lens group having a positive refractive power; the first lens group and the fifth lens group upon zooming from the short focal length end to the long focal length end Is fixed with respect to the image plane, and the second to fourth lens groups move in the optical axis direction; and the following conditional expressions (1-1) and (2-1) are satisfied: It is characterized by.
(1-1) 1.23 <f1 / f5 <1.50
(2-1) 1.20 <f5 / f3 <1.60
However,
f1: the focal length of the first lens group,
f3: focal length of the third lens group,
f5: focal length of the fifth lens group,
It is.

The zoom lens system of the present invention can be rewritten in a form in which the positive / negative / negative positive / positive five-group lens configuration is clarified without using the expressions of the “m-th lens group” and the “n-th lens group”. become that way.
That is, the zoom lens system of this aspect includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, and a positive lens group. A fourth lens group having a refractive power and a fifth lens group having a positive refractive power; the first lens group and the fifth lens group upon zooming from the short focal length end to the long focal length end Is fixed with respect to the image plane, and the second to fourth lens groups move in the optical axis direction; and the following conditional expressions (1-2) and (2-2) are satisfied: It is characterized by.
(1-2) 1.23 <f1 / f5 <1.50
(2-2) 1.20 <f5 / f4 <1.60
However,
f1: the focal length of the first lens group,
f4: focal length of the fourth lens group,
f5: focal length of the fifth lens group,
It is.

  Even if a lens or a lens group having no substantial power is added to the zoom lens system included in the scope of claims of the present invention, it is included in the technical scope of the present invention. It ’s not avoided.)

G1 First lens group 11 having a positive refractive power 11 Negative lens (negative lens with a concave surface facing the image side)
12 Positive lens (positive lens with convex surface facing the object)
13 Positive lens (positive lens with convex surface facing the object)
14 Positive lens (positive lens with convex surface facing the object)
G2 Second lens group 21 with negative refractive power Positive lens 22 Negative lens 23 Negative lens 24 Positive lens 25 Negative lens G3 Third lens group with positive refractive power (mth lens group, focus lens group)
31 Positive lens 32 Positive lens 33 Negative lens G4 Fourth lens group 41 with negative refractive power Negative single lens (negative single lens with a convex surface facing the image side)
G5 Fifth lens unit with positive refractive power (nth lens unit)
51 Positive lens 52 Positive lens 53 Negative lens 54 Positive lens (intermediate positive lens)
55 Negative lens 56 Positive lens G1 ′ First lens group 11 ′ having a positive refractive power Negative lens (negative lens with a concave surface facing the image side)
12 'positive lens (positive lens with convex surface facing the object)
13 'positive lens (positive lens with convex surface facing the object)
14 'positive lens (positive lens with convex surface facing the object)
G2 ′ second lens group 21 ′ having negative refractive power 21 ′ positive lens 22 ′ negative lens G3 ′ third lens group 31 ′ having negative refractive power negative lens 32 ′ positive lens 33 ′ negative lens G4 ′ first lens having positive refractive power 4 lens groups (mth lens group, focus lens group)
41 'positive lens 42' positive lens 43 'negative lens G5' positive refractive power fifth lens group (nth lens group)
51 'positive lens 52' positive lens 53 'negative lens 54' positive lens 55 'negative lens 56' positive lens (intermediate positive lens)
57 'Negative lens 58' Positive lens S Aperture stop I Image plane

Claims (5)

In order from the most object side, it has a first lens group having a positive refractive power and a second lens group having a negative refractive power, and has an nth lens group having a positive refractive power closest to the image side. Being;
In zooming from the short focal length end to the long focal length end, the first lens group and the nth lens group are fixed with respect to the image plane, and the second lens group moves in the optical axis direction;
Having an m-th lens group having a positive refractive power between the second lens group and the n-th lens group;
The first lens group includes, in order from the object side, a negative lens having a concave surface facing the image side, a positive lens having a convex surface facing the object side, a positive lens having a convex surface facing the object side, and a convex surface facing the object side. Consisting of a positive lens;
The n-th lens group has two or more positive lenses; and satisfies the following conditional expressions (1), (2) , (3), (4), (5) ;
Zoom lens system characterized by
(1) 1.23 <f1 / fn <1.50
(2) 1.20 <fn / fm <1.60
(3) νdp2>νdp1> νdp3
(4) Np1-Np2> 0
(5) νave> 68
However,
f1: the focal length of the first lens group,
fn: focal length of the nth lens group (n is a positive integer of 4 or more),
fm: focal length of the m-th lens group (m is a positive integer of 3 or more) ,
νdp1: Abbe number for the d-line of the positive lens located closest to the object side among the positive lenses in the first lens group,
νdp2: Abbe number for the d-line of the positive lens located second from the object side among the positive lenses in the first lens group,
νdp3: Abbe number for the d-line of the positive lens located third from the object side among the positive lenses in the first lens group,
Np1: the refractive index of the positive lens located closest to the object side among the positive lenses in the nth lens group with respect to the d-line,
Np2: refractive index with respect to d-line of the positive lens located second from the object side among the positive lenses in the nth lens group,
νave: The average value of the Abbe numbers for the d-line of the positive lens located closest to the object side and the positive lens located second from the object side among the positive lenses in the nth lens group. In order from the most object side, it has a first lens group having a positive refractive power and a second lens group having a negative refractive power, and has an nth lens group having a positive refractive power closest to the image side. Being;
In zooming from the short focal length end to the long focal length end, the first lens group and the nth lens group are fixed with respect to the image plane, and the second lens group moves in the optical axis direction;
Having an m-th lens group having a positive refractive power between the second lens group and the n-th lens group;
The first lens group includes, in order from the object side, a negative lens having a concave surface facing the image side, a positive lens having a convex surface facing the object side, a positive lens having a convex surface facing the object side, and a convex surface facing the object side. Consisting of a positive lens;
Satisfy the following conditional expressions (1), (2) , (3) ; and
An intermediate positive lens that satisfies the following conditional expressions (6), (7), and (8) is located between the most object side lens and the most image side lens in the nth lens group. about;
Zoom lens system characterized by
(1) 1.23 <f1 / fn <1.50
(2) 1.20 <fn / fm <1.60
(3) νdp2>νdp1> νdp3
(6) 0.5 <DnP / LDn <0.75
(7) 0.9 <fn / fnP <1.4
(8) 60 <νnP <75
However,
f1: the focal length of the first lens group,
fn: focal length of the nth lens group (n is a positive integer of 4 or more),
fm: focal length of the m-th lens group (m is a positive integer of 3 or more) ,
νdp1: Abbe number for the d-line of the positive lens located closest to the object side among the positive lenses in the first lens group,
νdp2: Abbe number for the d-line of the positive lens located second from the object side among the positive lenses in the first lens group,
νdp3: Abbe number for the d-line of the positive lens located third from the object side among the positive lenses in the first lens group,
DnP: distance from the object side surface of the most object side lens in the nth lens group to the object side surface of the intermediate positive lens,
LDn: Group thickness of the nth lens group,
fnP: focal length of the intermediate positive lens in the nth lens group,
νnP: Abbe number for the d-line of the intermediate positive lens in the nth lens group. In order from the most object side, it has a first lens group having a positive refractive power and a second lens group having a negative refractive power, and has an nth lens group having a positive refractive power closest to the image side. Being;
In zooming from the short focal length end to the long focal length end, the first lens group and the nth lens group are fixed with respect to the image plane, and the second lens group moves in the optical axis direction;
Having an m-th lens group having a positive refractive power between the second lens group and the n-th lens group;
Having a lens unit having a negative refractive power different from that of the m-th lens unit between the second lens unit and the n-th lens unit;
The first lens group includes, in order from the object side, a negative lens having a concave surface facing the image side, a positive lens having a convex surface facing the object side, a positive lens having a convex surface facing the object side, and a convex surface facing the object side. And satisfying the following conditional expressions (1), (2) , (3), (9) ;
Zoom lens system characterized by
(1) 1.23 <f1 / fn <1.50
(2) 1.20 <fn / fm <1.60
(3) νdp2>νdp1> νdp3
(9) -8.0 <fN / fm <-1.5
However,
f1: the focal length of the first lens group,
fn: focal length of the nth lens group (n is a positive integer of 4 or more),
fm: focal length of the m-th lens group (m is a positive integer of 3 or more) ,
νdp1: Abbe number for the d-line of the positive lens located closest to the object side among the positive lenses in the first lens group,
νdp2: Abbe number for the d-line of the positive lens located second from the object side among the positive lenses in the first lens group,
νdp3: Abbe number for the d-line of the positive lens located third from the object side among the positive lenses in the first lens group,
fN: the focal length of the lens unit having a negative refractive power located between the second lens unit and the nth lens unit. In order from the most object side, it has a first lens group having a positive refractive power and a second lens group having a negative refractive power, and has an nth lens group having a positive refractive power closest to the image side. Being;
In zooming from the short focal length end to the long focal length end, the first lens group and the nth lens group are fixed with respect to the image plane, and the second lens group moves in the optical axis direction;
Having an m-th lens group having a positive refractive power between the second lens group and the n-th lens group;
Having a lens unit having a negative refractive power different from that of the m-th lens unit between the second lens unit and the n-th lens unit;
The first lens group includes, in order from the object side, a negative lens having a concave surface facing the image side, a positive lens having a convex surface facing the object side, a positive lens having a convex surface facing the object side, and a convex surface facing the object side. Consisting of a positive lens;
The lens unit having a negative refractive power located between the second lens unit and the nth lens unit is composed of a negative single lens having a convex surface facing the image side; and the following conditional expression (1), Satisfy (2) , (3), (10), (11) ;
Zoom lens system characterized by
(1) 1.23 <f1 / fn <1.50
(2) 1.20 <fn / fm <1.60
(3) νdp2>νdp1> νdp3
(10) 1.55 <NdN <1.73
(11) 30 <νdN <60
However,
f1: the focal length of the first lens group,
fn: focal length of the nth lens group (n is a positive integer of 4 or more),
fm: focal length of the m-th lens group (m is a positive integer of 3 or more) ,
νdp1: Abbe number for the d-line of the positive lens located closest to the object side among the positive lenses in the first lens group,
νdp2: Abbe number for the d-line of the positive lens located second from the object side among the positive lenses in the first lens group,
νdp3: Abbe number for the d-line of the positive lens located third from the object side among the positive lenses in the first lens group,
NdN: a refractive index with respect to d line of a negative single lens constituting a lens unit having a negative refractive power located between the second lens unit and the nth lens unit,
νdN: Abbe number with respect to the d-line of a negative single lens constituting a lens unit having a negative refractive power located between the second lens unit and the nth lens unit. 5. The zoom lens system according to claim 1, wherein the zoom lens system has two or more lens groups including an m-th lens group between the second lens group and the n-th lens group. 6. system.

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