JP4799209B2 - Zoom lens system and camera system including the same - Google Patents

Description

  The present invention relates to a zoom lens system, and more particularly to a zoom lens system with a high variable magnification suitable as an imaging optical system used in an interchangeable lens apparatus of a so-called digital single lens reflex camera system.

  A camera body having an imaging element such as a CCD (Charge Coupled Device), CMOS (Complementary Metal-Oxide Semiconductor), and an interchangeable lens apparatus having an imaging optical system for forming an optical image on the light receiving surface of the imaging element The so-called digital single-lens reflex camera system (hereinafter simply referred to as “D-SLR”) in which the imaging lens system is removable from the camera body is rapidly expanding.

For example, zoom lens systems described in Patent Documents 1 to 5 have been proposed as zoom lens systems applicable to D-SLR.
JP 2005-352057 A JP 2005-107280 A JP 2004-258509 A JP 2004-226644 A JP 2004-212611 A

  Each zoom lens system described in the above-mentioned patent document is not a bright zoom lens system because it is about 3.6 in the example with the smallest F number at the wide-angle end. In addition, there is room for further improvement with respect to correction of distortion, particularly at the wide-angle end.

  In view of the above problems, the present invention provides a zoom lens system in which various aberrations including distortion at the wide-angle end are sufficiently corrected despite the fact that the F-number at the wide-angle end is as bright as 3 or less, and the zoom lens thereof An object is to provide a camera system using the system.

In order to achieve the above object, in the zoom lens system of the present invention, in order from the object side, a first lens group having a positive power, a second lens group having a negative power, and a third lens having a positive power. A lens group, a fourth lens group having negative power, and a positive power as a whole, and in order from the object side, are composed of a negative lens element, a positive lens element, a negative lens element, and a positive lens element It consists of a fifth lens group, upon zooming from the wide-angle end to the telephoto end, at least the first lens group, the third lens group, and the fifth lens group on the object side, an image of the second lens group Move to the side and the following conditions:
0.55 <√ (φ ₅₁ ² + φ ₅₃ ² ) / (φ ₅₂ ² + φ ₅₄ ² ) <0.70
1.8 <φ _51-52 / φ _53-54 <2.9
( Where φ _{5i is} the power of the i-th lens from the object side of the fifth lens group, φ _{51-52 is} the combined power of the first to second lenses from the object side of the fifth lens group, φ _53-54 : the from the object side of the fifth lens group is a composite power of the third to 4-th lens) and satisfying to said Rukoto a.

  Since the present invention has the above configuration, a zoom lens system in which various aberrations including distortion at the wide-angle end are sufficiently corrected even though the F-number at the wide-angle end is as bright as 3 or less. And a camera system using the zoom lens system can be provided.

(Embodiments 1 to 6)
FIG. 1 is a lens configuration diagram at the wide-angle end of an infinite object point in the zoom lens system according to Embodiment 1. FIG. 5 is a lens configuration diagram at the wide-angle end of an infinite object point in the zoom lens system according to Embodiment 2. FIG. 9 is a lens configuration diagram at the wide-angle end of an infinite object point in the zoom lens system according to Embodiment 3. FIG. 13 is a lens configuration diagram at the wide-angle end of an infinite object point in the zoom lens system according to Embodiment 4. FIG. 17 is a lens configuration diagram at the wide-angle end of an infinite object point in the zoom lens system according to Embodiment 5. FIG. 21 is a lens configuration diagram at the wide-angle end of an infinite object point in the zoom lens system according to Embodiment 6.

  In each figure, the zoom lens system according to each embodiment includes a first lens group G1 having a positive power in order from the object side to the image side (image plane S side) along the optical axis 101; A second lens group G2 having negative power, a third lens group G3 having positive power, a fourth lens group G4 having negative power, and a fifth lens group G5 having positive power are provided.

  In each figure, the solid single arrow in the figure indicates the movement trajectory of each lens group during zooming from the wide-angle end (WIDE) to the telephoto end (TELE). In the zoom lens system according to each embodiment, the first lens group G1, the third lens group G3, and the fifth lens group G5 are shown as solid lines when zooming from the wide-angle end (WIDE) to the telephoto end (TELE). It moves in a direction parallel to the optical axis 101 along the locus indicated by. The second lens group G2 moves toward the image side in a direction parallel to the optical axis along a locus indicated by a solid line along a direction parallel to the optical axis 101. The fourth lens group G4 is fixed with respect to the image plane S during zooming.

  During zooming, the interval between the third lens group G3 and the fifth lens group G5 described above is constant. That is, the third lens group G3 and the fifth lens group G5 are integrally held. In FIGS. 1, 5, 9, 13, 17, and 21, the fourth lens group G4 moves in a direction perpendicular to the optical axis 101 for image blur correction.

  In addition, the zoom lens system according to each embodiment has a stop A on the object side of the third lens group G3. At the time of zooming, the diaphragm A is changed in the first to third embodiments except for the second and fourth embodiments while changing the distance between them independently of the second lens group G2 and the third lens group G3. Move in a direction parallel to the optical axis. During zooming, the diaphragm A of Embodiments 2 and 4 moves in a direction parallel to the optical axis without changing the distance from the third lens group G3.

  In the zoom lens system of each embodiment, the first lens group G1 includes, in order from the object side, a negative meniscus lens element L1 having a convex surface facing the object side and a positive meniscus lens element having a convex surface facing the object side. It consists of a cemented lens element formed by cementing L2 and a positive meniscus lens element L3 having a convex surface facing the object side.

  The second lens group G2 includes, in order from the object side, a lens element (first lens element) L4 having a negative meniscus lens shape with a convex surface facing the object side, and a lens element (second lens) having a biconcave negative power. Lens element) L5, a biconvex lens element (third lens element) L6 having positive power, and a negative meniscus lens element (fourth lens element) L7 having a convex surface facing the image side.

  The third lens group G3 includes, in order from the object side, a biconvex lens element L8, a biconvex lens element L9, and a negative meniscus lens element L10 having a convex surface facing the image side. It consists of a lens element.

  The fourth lens group G4 includes, in order from the object side, a cemented lens element composed of a positive meniscus lens element L11 having a concave surface facing the object side and a negative power lens element L12 having a concave surface facing the object side. The most image-side surface of the cemented lens element included in the fourth lens group G4 is a surface with very low power. The most image-side surface of the cemented lens element included in the fourth lens group G4 is a concave surface in the first, fourth, fifth, and sixth embodiments, and a convex surface in the second and third embodiments.

  In the first and third to sixth embodiments, the fifth lens group G5 is formed by joining, in order from the object side, a negative meniscus lens element L13 having a convex surface facing the object side and a biconvex lens element L14. It consists of a cemented lens element, a negative lens element L15 having a concave surface facing the object side, and a biconvex positive lens element L16. In Embodiment 2, in order from the object side, a cemented lens element formed by cementing a negative meniscus lens element L13 having a convex surface facing the object side and a biconvex lens element L14, and a biconcave negative lens element. It consists of a cemented lens element formed by cementing a lens element L15 and a biconvex positive lens element L16, and a positive meniscus lens element L17 having a convex surface facing the object side. The second lens element from the image side of the fifth lens group G5 is a negative meniscus lens element with the concave surface facing the object side in the first and third embodiments, and both the fifth to sixth embodiments are both. It is a concave lens element.

  Hereinafter, conditions to be satisfied by the zoom lens system according to each embodiment will be described. In the zoom lens system according to each embodiment, a plurality of conditions to be satisfied are defined, but the configuration of the zoom lens system that satisfies all the conditions is most desirable. However, by satisfying individual conditions, it is possible to obtain a zoom lens system that exhibits the corresponding effects.

It is desirable that the zoom lens system satisfies the following expressions (1) and (2).
2.3 <BF _W / f _W <2.9 (1)
0.08 <T _22-23 / f _w <0.20 (2)
(35 <ω _w <40, 3.0 <f _t / f _w <5.0)
However,
BF _W : Back focus at the wide-angle end (distance along the optical axis between the lens disposed closest to the image side and the image plane),
f _W : focal length of the entire system at the wide-angle end,
ω _w : half angle of view at the wide-angle end,
f _t : focal length of the entire system at the telephoto end,
T _22-23 : the distance along the optical axis between the negative lens element included in the second lens group and the positive lens element arranged on the image side of the negative lens element,
It is.

Expression (1) is a condition for appropriately securing the back focus. If the lower limit of Expression (1) is exceeded, the back focus is too short, and the zoom lens system and the quick return mirror of the camera body interfere with each other in D-SLR, and the system is not established. If the upper limit of Expression ( 1 ) is exceeded, the back focus is too long, which makes it difficult to reduce the aberration of the zoom lens system.

  Expression (2) is an expression that appropriately defines the interval between the negative lens element and the positive lens element included in the second lens group. If the upper limit of equation (2) is exceeded, aberration correction will be good, but the entire system will become too large, which is not preferable. Exceeding the lower limit of the expression (2) is not preferable because the distortion at the wide-angle end becomes too large.

The second lens group, in order from the object side, a first lens element having a negative meniscus lens shape with a convex surface facing the object side, a second lens element having a negative power, and a third lens element having a positive power And the fourth lens element having negative power, it is desirable that the fourth lens element satisfies the following expression (3).
−3.0 <(r ₇₁ + r ₇₂ ) / (r ₇₁ −r ₇₂ ) <− 1.05 (3)
However,
r ₇₁ : radius of curvature of the object side surface of the fourth lens element,
r ₇₂ : radius of curvature of the image side surface of the fourth lens element,
It is.

  In the expression (3), the second lens group includes, in order from the object side, a first lens element having a negative meniscus lens shape having a convex surface directed toward the object side, a second lens element having a negative power, and a positive power. Is a formula that defines the shape of the fourth lens element included in the second lens group, when the third lens element has a negative power and the fourth lens element has a negative power. If the range of the expression (3) is exceeded, the astigmatism becomes too large and the performance deterioration becomes remarkable.

The second lens group, in order from the object side, a first lens element having a negative meniscus lens shape with a convex surface facing the object side, a second lens element having a negative power, and a third lens element having a positive power And the fourth lens element having negative power, it is desirable that the first lens element satisfies the following expressions (4) and (5).
1.05 <(r ₄₁ + r ₄₂ ) / (r ₄₁ −r ₄₂ ) <2.00 (4)
1.80 <Nd ₄ (5)
However,
r ₄₁ : radius of curvature of the object side surface of the first lens element,
r ₄₂ : radius of curvature of the image side surface of the first lens element,
Nd ₄ : refractive index with respect to d-line of the first lens element,
It is.

In the expression (4), the second lens group includes, in order from the object side, a first lens element having a negative meniscus lens shape having a convex surface facing the object side, a second lens element having negative power, and a positive power. Is a formula that defines the shape of the first lens element included in the second lens group when the third lens element has a fourth lens element having negative power. If the upper limit of Expression (4) is exceeded, the eccentricity error sensitivity becomes too high, and assembly adjustment becomes difficult. Exceeding the lower limit of formula (4) is not preferable because the distortion becomes too large.

In the formula (5), the second lens group includes, in order from the object side, a first lens element having a negative meniscus lens shape having a convex surface facing the object side, a second lens element having a negative power, and a positive power. Is a formula that defines the refractive index of the first lens element included in the second lens group when the third lens element includes a fourth lens element having negative power and a fourth lens element having negative power. If the range of the equation (5) is exceeded, the distortion becomes too large and the performance deteriorates.

The second lens group, in order from the object side, a first lens element having a negative meniscus lens shape with a convex surface facing the object side, a second lens element having a negative power, and a third lens element having a positive power And the fourth lens element having negative power, it is desirable that the second lens element satisfies the following expressions (6) and (7).
−0.70 <(r ₅₁ + r ₅₂ ) / (r ₅₁ −r ₅₂ ) <0.70 (6)
1.75 <Nd ₅ (7)
However,
r ₅₁ : radius of curvature of the object side surface of the second lens element,
r ₅₂ : radius of curvature of the image side surface of the second lens element,
Nd ₅ : refractive index with respect to d-line of the second lens element,
It is.

In the expression (6), the second lens group includes, in order from the object side, a first lens element having a negative meniscus lens shape having a convex surface facing the object side, a second lens element having a negative power, and a positive power. Is a formula that defines the shape of the second lens element included in the second lens group in the case where the third lens element has a negative power and a fourth lens element having a negative power. Exceeding the upper limit of Expression (6) is not preferable because coma at the telephoto end deteriorates. Exceeding the lower limit of equation (6) is not preferable because astigmatism at the wide-angle end deteriorates.

When the following expression (6) ′ is satisfied, the above effect can be further achieved.
−0.50 <(r ₅₁ + r ₅₂ ) / (r ₅₁ −r ₅₂ ) <0.50 (6) ′

In the expression (7), the second lens group includes, in order from the object side, a first lens element having a negative meniscus lens shape having a convex surface directed toward the object side, a second lens element having a negative power, and a positive power. Is a formula that defines the refractive index of the second lens element included in the second lens group, when the third lens element has a negative power and the fourth lens element has a negative power. Exceeding the range of Expression (7) is not preferable because the curvature of the lens becomes strong, and off-axis aberrations, particularly coma at the telephoto end, deteriorate.

The zoom lens system, it satisfies the following equation (8).
0.55 <√ (φ ₅₁ ² + φ ₅₃ ² ) / (φ ₅₂ ² + φ ₅₄ ² ) <0.70 (8)
However,
φ _5i : power of the i-th lens from the object side of the fifth lens group,
It is.

Expression (8) is an expression relating to power distribution between the positive power lens and the negative power lens in the fifth lens group. If the upper limit of Expression (8) is exceeded, the negative power in the fifth lens group becomes too large, so that the angle of light incident on the image sensor becomes tight and shading at the periphery of the screen increases. If the lower limit of Expression (8) is exceeded, the positive power increases and field curvature occurs on the object side.

It is desirable that the zoom lens system satisfies the following expression (9).
7.5 <TH ₈ / TH ₀ <27.0 (9)
However,
TH ₀ : the distance on the optical axis between the second lens and the third lens from the object side of the fifth lens group,
TH ₈ : interval at 80% of the lens diameter of the third lens from the object side of the fifth lens group,
It is.

  Expression (9) is an expression that defines the configuration of the fifth lens group. If the upper limit of equation (9) is exceeded, the tolerance for the spacing error of the fifth lens group can be relaxed, but the curvature radius of the object side surface of the fifth lens group becomes large, so that the off-axis aberration cannot be corrected sufficiently. Exceeding the lower limit of equation (9) causes a large deterioration in performance due to a large change in the angle of light incident on the object side surface of the fifth lens group, particularly when an error occurs in the interval and the tilt of the lens surface.

The zoom lens system, it satisfies the following equation (10).
1.8 <φ _51-52 / φ _53-54 <2.9 (10)
However,
φ _51-52 : the combined power of the first to second lenses from the object side of the fifth lens group,
φ _53-54 : _Combined power of the third to fourth lenses from the object side of the fifth lens group,
It is.

  Expression (10) is a condition for ensuring the back focus necessary for the D-SLR by optimizing the configuration of the fifth lens group. If the upper limit of Expression (10) is exceeded, the power of the cemented lens element on the object side of the fifth lens group becomes too large, so that the back focus becomes too short and the spherical aberration becomes large. If the lower limit of equation (10) is exceeded, the back focus can be lengthened, but the combined power of the two lens elements on the image side of the fifth lens group becomes too large, which is desirable because field curvature occurs on the object side. Absent.

It is desirable that the zoom lens system satisfies the following expression (11).
0.65 <φ _p / φ _n <1.55 (11)
However,
φ _p : the power of the image side surface of the second lens from the object side of the fifth lens group,
φ _n is the power of the object side surface of the third lens from the object side of the fifth lens group.

  Expression (11) is a condition for securing the back focus necessary for the D-SLR by optimizing the configuration of the fifth lens group. If the upper limit of Expression (11) is exceeded, the power on the image side surface of the second lens from the object side of the fifth lens group becomes too large, so that the back focus becomes too short and the spherical aberration becomes large. If the lower limit of Expression (11) is exceeded, the back focus can be lengthened, but the power of the object side surface of the third lens from the object side of the fifth lens group becomes too large, causing field curvature on the object side. Not desirable.

It is desirable that the zoom lens system satisfies the following expression (12).
−4.0 × 10 ⁻² <(φ ₅₁ ν ₅₂ + φ ₅₂ ν ₅₁ ) / ν ₅₁ ν ₅₂ (φ ₅₁ + φ ₅₂ ) <− 2.5 × 10 ⁻⁴ (12)
However,
φ ₅₁ : Power of the first lens from the object side of the fifth lens group,
φ ₅₂ : the power of the second lens from the object side of the fifth lens group,
ν ₅₂ : Abbe number of the first lens from the object side of the fifth lens group,
ν ₅₁ : Abbe number of the second lens from the object side of the fifth lens group,
It is.

  Expression (12) is a condition for correcting chromatic aberration. If the upper limit of Expression (12) is exceeded, the combined dispersion of the cemented lens elements of the fifth lens group will increase, and the short wavelength side chromatic aberration will increase. Exceeding the lower limit of the expression (12) is not desirable because the combined dispersion of the cemented lens elements of the fifth lens group becomes too small and the effect of correcting chromatic aberration cannot be obtained sufficiently.

  Each lens group constituting each embodiment is constituted only by a refractive lens that deflects incident light by refraction (that is, a lens that is deflected at the interface between media having different refractive indexes). However, it is not limited to this. For example, a diffractive lens that deflects incident light by diffraction, a refractive / diffractive hybrid lens that deflects incident light by a combination of diffraction and refraction, and a refractive index distribution type that deflects incident light according to the refractive index distribution in the medium Each lens group may be constituted by a lens or the like.

(Embodiment 7)
FIG. 25 is a schematic diagram of a camera system according to the seventh embodiment. In FIG. 25, the camera system mainly includes an interchangeable lens device 300 and a camera body 400. The interchangeable lens device 300 can be attached to and detached from the camera body 400. The interchangeable lens device 300 holds an imaging lens system 301 therein. The imaging lens system 301 is the zoom lens system according to any one of the first to sixth embodiments described above. The camera body includes, for example, a quick return mirror 401 for switching an optical path, an image sensor 402 that receives an optical image formed by a zoom lens system, and converts it into an electrical image signal, a liquid crystal display 403, and a focusing screen 404, a pentaprism 405, and an eyepiece lens system 406.

  Since the camera system according to the seventh embodiment includes any one of the zoom lens systems according to the first to sixth embodiments, an electrical image signal can be generated based on a good optical image.

ただし、
Ｈ ：光軸からの高さ
ＣＲ ：曲率半径（ｍｍ）
Ｋ ：コーニック係数
Ａｎ ：ｎ次の非球面係数
である。 Hereinafter, numerical examples in which the zoom lens systems according to Embodiments 1 to 6 are specifically implemented will be described. In each numerical example, the unit of length in the table is mm. In each numerical example, r is a radius of curvature, d is a surface interval, nd is a refractive index in the d line, and νd is an Abbe number. In each numerical example, the surface marked with * is an aspherical surface, and the aspherical shape is defined by the following equation.

However,
H: Height from the optical axis CR: Radius of curvature (mm)
K: conic coefficient An: n-order aspheric coefficient.

Example 1
The zoom lens system of Example 1 corresponds to Embodiment 1 shown in FIG. Table 1 shows lens data of the zoom lens system of Example 1, Table 2 shows aspheric data, and Table 3 shows variable surface interval data. It should be noted that the focal length f and F number FNo. And the angle of view 2ω (each from the wide-angle end to the telephoto end) are as follows.
f: 14.6-49.0
FNo. : 2.91-3.64
2ω: 75.4 ° to 25.2 °

  FIG. 2 is a longitudinal aberration diagram at an infinite object point at the wide-angle end of the zoom lens system according to Example 1. FIG. 3 is a longitudinal aberration diagram at an infinite object point in the intermediate focal length state of the zoom lens system of Example 1. FIG. 4 is a longitudinal aberration diagram at an infinite object point at the telephoto end of the zoom lens system according to Example 1. 2 to 4, (a) is the spherical aberration of the d line, (b) is the astigmatism of the d line, the solid line is the sagittal direction (indicated by s in the figure), and the broken line is the meridional direction (in the figure, m). Further, (c) shows a distortion diagram of the d line.

(Example 2)
The zoom lens system of Example 2 corresponds to Embodiment 2 shown in FIG. Table 4 shows lens data of the zoom lens system of Example 2, Table 5 shows aspheric data, and Table 6 shows variable surface interval data. It should be noted that the focal length f and F number FNo. And the angle of view 2ω (each from the wide-angle end to the telephoto end) are as follows.
f: 14.4-48.5
FNo. : 2.89 to 3.59
2ω: 77.3 ° to 26.0 °

  FIG. 6 is a longitudinal aberration diagram at an infinite object point at the wide-angle end of the zoom lens system according to Example 2. FIG. 7 is a longitudinal aberration diagram at an infinite object point in the intermediate focal length state of the zoom lens system of Example 2. FIG. 8 is a longitudinal aberration diagram at an infinite object point at the telephoto end of the zoom lens system according to Example 2. 6-8, (a) is the spherical aberration of the d line, (b) is the astigmatism of the d line, the solid line is the sagittal direction (indicated by s in the figure), and the broken line is the meridional direction (in the figure, m). Further, (c) shows a distortion diagram of the d line.

(Example 3)
The zoom lens system of Example 3 corresponds to the third embodiment shown in FIG. Table 7 shows lens data of the zoom lens system of Example 3, Table 8 shows aspherical data, and Table 9 shows variable surface interval data. It should be noted that the focal length f and F number FNo. And the angle of view 2ω (each from the wide-angle end to the telephoto end) are as follows.
f: 12.2-48.3
FNo. : 2.91-3.64
2ω: 84.9 ° to 23.1 °

  FIG. 10 is a longitudinal aberration diagram at an infinite object point at the wide-angle end of the zoom lens system according to Example 3. FIG. 11 is a longitudinal aberration diagram at an infinite object point in the intermediate focal length state of the zoom lens system of Example 3. FIG. 12 is a longitudinal aberration diagram at an infinite object point at the telephoto end of the zoom lens system according to Example 3. 10-12, (a) is d-line spherical aberration, (b) is d-line astigmatism, solid line is sagittal direction (indicated by s in the figure), and broken line is meridional direction (in the figure, m). Further, (c) shows a distortion diagram of the d line.

Example 4
The zoom lens system of Example 4 corresponds to Embodiment 4 shown in FIG. Table 10 shows lens data of the zoom lens system of Example 4, Table 11 shows aspherical data, and Table 12 shows variable surface interval data. It should be noted that the focal length f and F number FNo. And the angle of view 2ω (each from the wide-angle end to the telephoto end) are as follows.
f: 14.63-49.04
FNo. : 2.91-3.62
2ω: 76.7 ° to 25.3 °

  FIG. 14 is a longitudinal aberration diagram at an infinite object point at the wide-angle end of the zoom lens system according to Example 4. FIG. 15 is a longitudinal aberration diagram at an infinite object point in the intermediate focal length state of the zoom lens system of Example 4. FIG. 16 is a longitudinal aberration diagram at an infinite object point at the telephoto end of the zoom lens system according to Example 4. 14 to 16, (a) is the spherical aberration of the d line, (b) is the astigmatism of the d line, the solid line is the sagittal direction (indicated by s in the figure), and the broken line is the meridional direction (in the figure, m). Further, (c) shows a distortion diagram of the d line.

(Example 5)
The zoom lens system of Example 5 corresponds to the fifth embodiment shown in FIG. Table 13 shows lens data of the zoom lens system of Example 5, Table 14 shows aspheric data, and Table 15 shows variable surface interval data. It should be noted that the focal length f and F number FNo. And the angle of view 2ω (each from the wide-angle end to the telephoto end) are as follows.
f: 14.46 to 48.47
FNo. : 2.86-3.88
2ω: 77.2 ° to 25.2 °

  FIG. 18 is a longitudinal aberration diagram at an infinite object point at the wide-angle end of the zoom lens system according to Example 5. FIG. 19 is a longitudinal aberration diagram at an infinite object point in the intermediate focal length state of the zoom lens system of Example 5. FIG. 20 is a longitudinal aberration diagram at an infinite object point at the telephoto end of the zoom lens system according to Example 5. 18-20, (a) is the d-line spherical aberration, (b) is the d-line astigmatism, the solid line is the sagittal direction (indicated by s in the figure), and the broken line is the meridional direction (in the figure, m). Further, (c) shows a distortion diagram of the d line.

(Example 6)
The zoom lens system of Example 6 corresponds to Embodiment 6 shown in FIG. Table 16 shows lens data of the zoom lens system of Example 6, Table 17 shows aspherical data, and Table 18 shows variable surface interval data. It should be noted that the focal length f and F number FNo. And the angle of view 2ω (each from the wide-angle end to the telephoto end) are as follows.
f: 14.63-49.14
FNo. : 2.94 to 3.54
2ω: 75.6 ° to 24.8 °

  FIG. 22 is a longitudinal aberration diagram at an infinite object point at the wide-angle end of the zoom lens system according to Example 6. FIG. 23 is a longitudinal aberration diagram at an infinite object point in the intermediate focal length state of the zoom lens system according to the sixth embodiment. FIG. 24 is a longitudinal aberration diagram at an infinite object point at the telephoto end of the zoom lens system according to Example 6. 22 to 24, (a) is the spherical aberration of the d line, (b) is the astigmatism of the d line, the solid line is the sagittal direction (indicated by s in the figure), and the broken line is the meridional direction (in the figure, m). Further, (c) shows a distortion diagram of the d line.

  The zoom lens system according to the present invention is applicable to digital input devices such as a digital still camera, a digital video camera, a mobile phone device, a PDA (Personal Digital Assistance), a surveillance camera in a surveillance system, a web camera, an in-vehicle camera, It is particularly suitable for a photographing optical system that requires high image quality, such as a digital still camera and a digital video camera.

FIG. 6 is a lens configuration diagram at the wide-angle end of an infinite object point in the zoom lens system according to Embodiment 1 (Example 1). Longitudinal aberration diagram at infinity at the wide angle end of the zoom lens system of Example 1 Longitudinal aberration diagram of the zoom lens system of Example 1 at an infinite object point in the intermediate focus state Longitudinal aberration diagram at the infinite object point at the telephoto end of the zoom lens system of Example 1 Lens configuration diagram at the wide-angle end of an infinite object point in the zoom lens system according to Embodiment 2 (Example 2) Longitudinal aberration diagram at infinity at the wide-angle end of the zoom lens system according to Example 2 Longitudinal aberration diagram at an infinite object point in the intermediate focus state of the zoom lens system of Example 2 Longitudinal aberration diagram at the infinite object point at the telephoto end of the zoom lens system of Example 2 Lens configuration diagram at the wide-angle end of an infinite object point in the zoom lens system according to Embodiment 3 (Example 3) Longitudinal aberration diagram at infinity at the wide angle end of the zoom lens system according to Example 3 Longitudinal aberration diagram at an infinite object point in the intermediate focus state of the zoom lens system of Example 3 Longitudinal aberration diagram at the infinity object point at the telephoto end of the zoom lens system of Example 3 Lens configuration diagram at the wide-angle end of an infinite object point in the zoom lens system according to Embodiment 4 (Example 4) Longitudinal aberration diagram at infinity at the wide-angle end of the zoom lens system according to Example 4 Longitudinal aberration diagram at infinity object point in the intermediate focus state of the zoom lens system of Example 4 Longitudinal aberration diagram at the infinite object point at the telephoto end of the zoom lens system of Example 4 Lens configuration diagram at the wide-angle end of an infinite object point in the zoom lens system according to Embodiment 5 (Example 5) Longitudinal aberration diagram at the infinite point at the wide angle end of the zoom lens system according to Example 5 Longitudinal aberration diagram of the zoom lens system of Example 5 at an object point at infinity in the intermediate focus state Longitudinal aberration diagram at the infinity object point at the telephoto end of the zoom lens system of Example 5 Lens configuration diagram at the wide-angle end of an infinite object point in the zoom lens system according to Embodiment 6 (Example 6) Longitudinal aberration diagram at infinity at the wide angle end of the zoom lens system according to Example 6 Longitudinal aberration diagram at infinity object point in the intermediate focus state of the zoom lens system of Example 6 Longitudinal aberration diagram at the infinite object point at the telephoto end of the zoom lens system of Example 6 Schematic diagram of camera system of Embodiment 7

Explanation of symbols

101 Optical axis S Image plane A Aperture G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group G5 Fifth lens group 300 Interchangeable lens device 301 Shooting lens system 400 Camera body 401 Quick return mirror 402 Imaging Element 403 Liquid crystal display 404 Focusing plate 405 Penta prism 406 Eyepiece system

Claims (6)

From the object side,
A first lens group having positive power;
A second lens group having negative power;
A third lens group having positive power;
A fourth lens group having negative power;
Overall it has a positive power, in order from the object side, a negative lens element, a positive lens element, a negative lens element, a fifth lens group composed of a positive lens element,
At the time of zooming from the wide angle end to the telephoto end, at least the first lens group, the third lens group, and the fifth lens group are moved to the object side, and the second lens group is moved to the image side ,
The zoom lens system according to claim 1, satisfying the following conditions:
0.55 <√ (φ ₅₁ ² + φ ₅₃ ² ) / (φ ₅₂ ² + φ ₅₄ ² ) <0.70
1.8 <φ _51-52 / φ _53-54 <2.9
However,
φ _5i : power of the i-th lens from the object side of the fifth lens group,
φ _51-52 : the combined power of the first to second lenses from the object side of the fifth lens group,
φ _53-54 : _Combined power of the third to fourth lenses from the object side of the fifth lens group,
It is .   2. The zoom lens system according to claim 1, wherein an interval between the third lens group and the fifth lens group is constant during zooming from the wide-angle end to the telephoto end. The zoom lens system according to claim 1, satisfying the following conditions:
7.5 <TH ₈ / TH ₀ <27.0
However,
TH ₀ : the distance on the optical axis between the second lens and the third lens from the object side of the fifth lens group,
TH ₈ : interval at 80% of the lens diameter of the third lens from the object side of the fifth lens group,
It is. The zoom lens system according to claim 1, satisfying the following conditions:
0.65 <φ _p / φ _n <1.55
However,
φ _p : the power of the image side surface of the second lens from the object side of the fifth lens group,
φ _n is the power of the object side surface of the third lens from the object side of the fifth lens group. The zoom lens system according to claim 1, satisfying the following conditions:
−4.0 × 10 ⁻² <(φ ₅₁ ν ₅₂ + φ ₅₂ ν ₅₁ ) / ν ₅₁ ν ₅₂ (φ ₅₁ + φ ₅₂ ) <− 2.5 × 10 ⁻⁴
However,
φ ₅₁ : Power of the first lens from the object side of the fifth lens group,
φ ₅₂ : the power of the second lens from the object side of the fifth lens group,
ν ₅₂ : Abbe number of the first lens from the object side of the fifth lens group,
ν ₅₁ : Abbe number of the second lens from the object side of the fifth lens group,
It is. An interchangeable lens device comprising the zoom lens system according to claim 1;
And a camera body including an image sensor that is connected to the interchangeable lens device and receives an optical image formed by the zoom lens system and converts the optical image into an electrical image signal.

Images