JP5097449B2 - Zoom lens system, imaging device and camera - Google Patents

Description

  The present invention relates to a zoom lens system, an imaging apparatus, and a camera. In particular, the present invention is suitable for a so-called collapsible lens barrel, a zoom lens system having a wide angle of view at a wide-angle end and a zooming ratio exceeding 3.2 times, while being extremely thin when stored. The present invention relates to an imaging device including a zoom lens system and a thin and compact camera including the imaging device.

  There is a strong demand for miniaturization of a camera having an image pickup device that performs photoelectric conversion (hereinafter simply referred to as a digital camera) such as a digital still camera or a digital video camera. In particular, in digital cameras equipped with a zoom lens system that has the largest sales volume in the market and has a zooming ratio of about 3 times, the total length of the lens barrel is shortened (collapsed) when retracted (non-shooting). A form having an exterior structure in which the tube itself does not protrude to the outside is gaining popularity. In recent years, there has also been a demand for a zoom lens system having a wide angle range with a wide shooting range.

  As a zoom lens system suitable for the digital camera as described above, for example, the following zoom lens system has been proposed.

  For example, Patent Document 1 includes, in order from the object side, a first lens group having a negative power and a second lens group having a positive power, and the distance between the first and second lens groups at the time of zooming from the wide angle end to the telephoto end. Is a variable magnification optical system in which the first lens group is composed of two or more lenses, and at least three lens groups are composed of only a single lens or a cemented lens.

  Patent Document 2 includes, in order from the object side, a negative power first lens group having a plurality of lenses and a positive power second lens group, and the first and second lenses at the time of zooming from the wide-angle end to the telephoto end. The distance between the two lens groups is narrowed, the first lens group has at least one aspheric surface, and the maximum value of the refractive index difference (absolute value) between the two lenses in the first lens group, and the second lens group A variable power optical system is disclosed in which the combined focal length and the distance on the optical axis from the surface vertex of the lens surface on the most image pickup device side to the image pickup device surface at the telephoto end all satisfy predetermined conditions.

  Patent Document 3 has a first lens group having a negative refractive power and a second lens group having a positive refractive power in order from the object side to the image side, and the distance between both lens groups changes during zooming. One lens group includes an eleventh lens having a negative refractive power and a twelfth lens having a positive refractive power, and a second lens group includes a twenty-first lens having a positive refractive power and a twenty-second lens having a negative refractive power. A zoom lens in which the Abbe numbers of the twenty-first and twenty-second lenses satisfy a predetermined condition is disclosed.

  Patent Document 4 has a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power in order from the object side to the image side. The distance between the lens groups changes, the first lens group is composed of one negative lens and one positive lens, and the second lens group is composed of one positive lens and one negative lens. 2a lens group, and 2b lens group which is arranged on the image side of the 2a lens group and has at least one positive lens, and the third lens group has at least one positive lens, and the second lens Zoom in which the imaging magnification at the wide-angle end and the telephoto end of the group, the distance at the wide-angle end of the first and second lens groups, and the distance at the telephoto end of the second and third lens groups satisfy predetermined conditions A lens is disclosed.

  Patent Document 5 has, in order from the object side to the image side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, and during zooming. The distance between the lens groups is changed, and the second lens group is disposed on the image side of the second a lens group and the second a lens group including a positive lens and a negative lens in order from the object side to the image side. 2b lens group including the positive lens, and the half field angle at the wide angle end, the focal length of the first and second lens groups, and the focal length of the entire system at the wide angle end satisfy predetermined conditions. A zoom lens is disclosed.

  Patent Document 6 has, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, and an interval between each lens group. The second lens group is composed of two lens components, a single lens on the object side and a lens component on the image side, and the curvature radius and lens on the object side and the image side of the single lens. A zoom lens in which the thickness on the optical axis satisfies a predetermined condition is disclosed.

  Patent Document 7 has, in order from the object side to the image side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, and during zooming. The interval between the lens groups changes, the first lens group is composed of one negative lens and one positive lens in order from the object side to the image side, and the second lens group is sequentially positive lens from the object side to the image side. And a positive lens, a negative lens, and a positive lens, and a zoom lens is disclosed in which the third lens unit moves to the image side during zooming from the wide-angle end to the telephoto end.

  Patent Document 8 has a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power in order from the object side to the image side. The distance between each lens group changes, the amount of movement of the second lens group during zooming from the wide-angle end to the telephoto end, the distance between the second and third lens groups at the wide-angle end, and the first and second lens groups A zoom lens is disclosed in which the focal length and the focal length of the entire system at the wide-angle end satisfy a predetermined condition.

  Patent Document 9 has at least a first lens group consisting of two components and a second lens group consisting of one component in order from the object side, and at the time of zooming, the distance between at least the first and second lens groups changes. The first and second lens groups both have aspheric surfaces, the paraxial radius of curvature of at least one aspheric surface A of the first lens group and the intersection point when the most off-axis principal ray passes through the aspheric surface A, A zoom lens is disclosed in which the distance between the optical axes satisfies a predetermined condition.

  Patent Document 10 has a first lens group having a negative refractive power and a second lens group having a positive refractive power in order from the object side to the image side, and the distance between each group is changed to telephoto from the wide-angle end. The first lens unit is composed of two lenses, a negative lens and a positive lens, in order from the object side. The Abbe number of the positive lens, the refractive index of the positive lens, and the refractive index of the negative lens are predetermined. A zoom lens that satisfies the conditions is disclosed.

Patent Document 11 includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. The first lens group is composed of two negative lenses and a positive lens, the second lens group is composed of two positive lenses and one negative lens, and the third lens group. Is a single positive lens, and a zoom lens in which the refractive index of the negative lens of the first lens group and the refractive index of the positive lens satisfy predetermined conditions is disclosed.
JP 2005-331860 A JP 2006-011096 A JP 2006-023679 A JP 2006-065034 A JP 2006-084829 A JP 2006-139187 A JP 2006-171421 A JP 2006-208890 A JP 2006-350027 A JP 2006-194974 A JP 2006-220715 A

  However, although all of the optical systems disclosed in Patent Documents 1 to 11 have a zooming ratio that can be applied to a digital camera, the wide angle of view at the wide angle end and the miniaturization are not realized at the same time. In particular, in terms of miniaturization, the demands of recent digital cameras cannot be satisfied.

  An object of the present invention is a zoom lens system suitable for a so-called collapsible type lens barrel, having a very small thickness during storage, a wide angle of view at the wide-angle end, and a zooming ratio of about 3 times. An imaging apparatus including a lens system, and a thin and compact camera including the imaging apparatus.

One of the above objects is achieved by the following zoom lens system. That is, the present invention
In order from the object side to the image side consists of a first lens unit having negative optical power, a second lens group having a positive power, a third lens unit having positive optical power,
In order from the object side to the image side, the first lens group includes a first lens element having a concave surface at least on the image side and having negative power, and a second lens element having a convex surface at least on the object side and having positive power. And two lens elements,
The second lens group, in order from the object side to the image side, a first cemented lens element formed by cementing a third lens element and a fourth lens element having different powers, respectively, and a different code A second cemented lens element formed by cementing a fifth lens element and a sixth lens element having the following power:
During zooming from the wide-angle end to the telephoto end, the first lens group, the second lens group, and the third lens group all move along the optical axis,
The following conditions (1) and (2):
5.0 <αi _W <20.0 (1)
(N ₁₁ −1) · (n ₁₂ −1) ≧ 0.84 (2)
(However, 3.2 <f _T / f _W , ω _W > 35)
(here,
αi _W : imaging element incident angle of the principal ray at the maximum image height at the wide-angle end (when the principal ray is incident on the light receiving surface of the imaging element while being separated from the optical axis)
n ₁₁ : refractive index with respect to d-line of the first lens element,
n ₁₂ : refractive index with respect to d-line of the second lens element,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W is the focal length of the entire system at the wide-angle end)
The present invention relates to a zoom lens system that satisfies the above.

One of the above objects is achieved by the following imaging device. That is, the present invention
An imaging apparatus capable of outputting an optical image of an object as an electrical image signal,
A zoom lens system that forms an optical image of the object;
An image sensor that converts an optical image formed by the zoom lens system into an electrical image signal;
The zoom lens system is
In order from the object side to the image side consists of a first lens unit having negative optical power, a second lens group having a positive power, a third lens unit having positive optical power,
In order from the object side to the image side, the first lens group includes a first lens element having a concave surface at least on the image side and having negative power, and a second lens element having a convex surface at least on the object side and having positive power. And two lens elements,
The second lens group, in order from the object side to the image side, a first cemented lens element formed by cementing a third lens element and a fourth lens element having different powers, respectively, and a different code A second cemented lens element formed by cementing a fifth lens element and a sixth lens element having the following power:
During zooming from the wide-angle end to the telephoto end, the first lens group, the second lens group, and the third lens group all move along the optical axis,
The following conditions (1) and (2):
5.0 <αi _W <20.0 (1)
(N ₁₁ −1) · (n ₁₂ −1) ≧ 0.84 (2)
(However, 3.2 <f _T / f _W , ω _W > 35)
(here,
αi _W : imaging element incident angle of the principal ray at the maximum image height at the wide-angle end (when the principal ray is incident on the light receiving surface of the imaging element while being separated from the optical axis)
n ₁₁ : refractive index with respect to d-line of the first lens element,
n ₁₂ : refractive index with respect to d-line of the second lens element,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W is the focal length of the entire system at the wide-angle end)
The present invention relates to an imaging apparatus that satisfies the above.

One of the above objects is achieved by the following camera. That is, the present invention
A camera that converts an optical image of an object into an electrical image signal, and displays and stores the converted image signal;
An image pickup apparatus including a zoom lens system that forms an optical image of an object, and an image sensor that converts an optical image formed by the zoom lens system into an electrical image signal;
The zoom lens system is
In order from the object side to the image side consists of a first lens unit having negative optical power, a second lens group having a positive power, a third lens unit having positive optical power,
In order from the object side to the image side, the first lens group includes a first lens element having a concave surface at least on the image side and having negative power, and a second lens element having a convex surface at least on the object side and having positive power. And two lens elements,
The second lens group, in order from the object side to the image side, a first cemented lens element formed by cementing a third lens element and a fourth lens element having different powers, respectively, and a different code A second cemented lens element formed by cementing a fifth lens element and a sixth lens element having the following power:
During zooming from the wide-angle end to the telephoto end, the first lens group, the second lens group, and the third lens group all move along the optical axis,
The following conditions (1) and (2):
5.0 <αi _W <20.0 (1)
(N ₁₁ −1) · (n ₁₂ −1) ≧ 0.84 (2)
(However, 3.2 <f _T / f _W , ω _W > 35)
(here,
αi _W : imaging element incident angle of the principal ray at the maximum image height at the wide-angle end (when the principal ray is incident on the light receiving surface of the imaging element while being separated from the optical axis)
n ₁₁ : refractive index with respect to d-line of the first lens element,
n ₁₂ : refractive index with respect to d-line of the second lens element,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W is the focal length of the entire system at the wide-angle end)
Satisfying the camera.

  According to the present invention, there is provided a zoom lens system suitable for a so-called retractable lens barrel, which has a very small thickness during storage, has a wide angle of view at the wide-angle end, and a zooming ratio exceeding 3.2 times. Can be provided. Furthermore, according to the present invention, an imaging device including the zoom lens system and a thin and compact camera including the imaging device can be provided.

(Embodiments 1 to 8)
FIG. 1 is a lens arrangement diagram of the zoom lens system according to Embodiment 1. FIG. FIG. 4 is a lens arrangement diagram of the zoom lens system according to Embodiment 2. FIG. 7 is a lens arrangement diagram of the zoom lens system according to Embodiment 3. FIG. 10 is a lens arrangement diagram of the zoom lens system according to Embodiment 4. FIG. 13 is a lens arrangement diagram of the zoom lens system according to Embodiment 5. FIG. 16 is a lens layout diagram of the zoom lens system according to Embodiment 6. FIG. 19 is a lens layout diagram of the zoom lens system according to Embodiment 7. FIG. 22 is a lens layout diagram of the zoom lens system according to Embodiment 8.

1, 4, 7, 10, 13, 16, 19, and 22 each represent a zoom lens system in an infinitely focused state. In each figure, (a) shows the lens configuration at the wide angle end (shortest focal length state: focal length f _W ), and (b) shows the intermediate position (intermediate focal length state: focal length f _M = √ (f _W * f). _T )) shows a lens configuration, and FIG. 8C shows a lens configuration at the telephoto end (longest focal length state: focal length f _T ). Also, in each figure, the broken line arrows provided between FIGS. (A) and (b) are obtained by connecting the positions of the lens groups in the wide-angle end, the intermediate position, and the telephoto end in order from the top. Straight line. Therefore, between the wide-angle end and the intermediate position, and between the intermediate position and the telephoto end are simply connected by a straight line, which is different from the actual movement of each lens group. Furthermore, in each figure, the arrow attached to the lens group represents the focusing from the infinite focus state to the close object focus state. That is, the moving direction during focusing from the infinitely focused state to the close object focused state is shown.

The zoom lens system according to each embodiment includes, in order from the object side to the image side, a first lens group G1 having a negative power, a second lens group G2 having a positive power, and a first lens group having a positive power. a three lens group G3, upon zooming from the wide-angle end to the telephoto end, first lens group G1, the second lens group G2 and the third lens group G3 all move along the optical axis (hereinafter, the lens The configuration is referred to as a basic configuration of the embodiment). The zoom lens system according to each embodiment achieves a zooming ratio exceeding 3.2 times by making each of these lens groups have a desired power arrangement, maintains a high optical performance, and is small in size of the entire lens system. Making it possible.

  1, 4, 7, 10, 13, 16, 19, and 22, an asterisk * attached to a specific surface indicates that the surface is aspherical. In each figure, a symbol (+) and a symbol (−) attached to a symbol of each lens group correspond to a power symbol of each lens group. In each figure, the straight line described on the rightmost side represents the position of the image plane S, and is located on the object side of the image plane S (between the image plane S and the most image side lens surface of the third lens group G3). Are provided with a parallel flat plate equivalent to an optical low-pass filter, a face plate of an image sensor, or the like. Further, in each drawing, a diaphragm A is provided between the most image side lens surface of the first lens group G1 and the most object side lens surface of the second lens group G2.

  As shown in FIG. 1, in the zoom lens system according to Embodiment 1, the first lens group G1 is a negative meniscus first lens element L1 having a convex surface directed toward the object side in order from the object side to the image side. And a positive meniscus second lens element L2 having a convex surface facing the object side. Each of the first lens element L1 and the second lens element L2 has a high refractive index with respect to the d-line.

  In the zoom lens system according to Embodiment 1, the second lens group G2 includes, in order from the object side to the image side, a biconvex third lens element L3, a biconcave fourth lens element L4, and both It consists of a convex fifth lens element L5 and a negative meniscus sixth lens element L6 with the convex surface facing the image side. Among these, the third lens element L3 and the fourth lens element L4 are cemented, and the fifth lens element L5 and the sixth lens element L6 are cemented.

  In the zoom lens system according to Embodiment 1, the third lens unit G3 comprises solely a bi-convex seventh lens element L7.

  In the zoom lens system according to Embodiment 1, a parallel plate L8 is provided on the object side of the image plane S (between the image plane S and the seventh lens element L7).

  In the zoom lens system according to Embodiment 1, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus that is convex toward the image side while changing the distance from the second lens group G2. The second lens group G2 moves to the object side, and the third lens group G3 moves to the image side.

  The zoom lens system according to Embodiment 1 includes a first lens element L1 having a concave surface on the image side and having negative power, and a convex surface on the object side, particularly constituting the first lens group G1, as shown later in Table 25. The refractive index of the second lens element L2 having positive power is high. By setting both the first lens element L1 and the second lens element L2 to have a high refractive index, the lens thickness in the optical axis direction of each lens element can be reduced and the curvature radius of the lens can be increased. Further, by reducing the refractive index difference between the lens elements, the Petzval sum can be easily controlled, so that field curvature can be corrected appropriately. In addition, aberration correction is possible without using a strong power surface with a small radius of curvature, so off-axis aberrations that are particularly problematic with zoom lens systems with a wide angle of view at the wide-angle end, especially distortion at the wide-angle end Astigmatism can be easily corrected.

  In the zoom lens system according to Embodiment 1, the second lens group G2 includes a first cemented lens element in which a third lens element L3 having positive power and a fourth lens element L4 having negative power are cemented. The second lens element is composed of a fifth lens element L5 having positive power and a sixth lens element L6 having negative power. As in the zoom lens system according to Embodiment 1, when the entire power is increased using a glass material having a high refractive index in the first lens group G1, the incident of the principal ray incident on the second lens group G2 Although the angle increases, the second lens group G2 adopts the above-described configuration, so that it is possible to appropriately correct off-axis aberration that occurs in such a case. Further, in the zoom lens system according to Embodiment 1, since the decentration error sensitivity of the first cemented lens element and the second cemented lens element is small, it is possible to allow a large error in the incorporation of these lens elements. Therefore, the zoom lens system according to Embodiment 1 can realize a configuration that is easy to manufacture with little performance deterioration when decentering even with an off-axis chief ray having a large incident angle. As in the zoom lens system according to Embodiment 1, it is desirable that the object side surface of the third lens element L3 is a convex surface and the image side surface of the fourth lens element L4 is a concave surface. With this configuration, the aberration generated on the convex surface can be canceled by the aberration generated on the concave surface, so that both the on-axis spherical aberration and the off-axis coma aberration can be corrected well.

  As shown in FIG. 4, in the zoom lens system according to Embodiment 2, the first lens unit G1 includes a negative meniscus first lens element L1 having a convex surface directed toward the object side in order from the object side to the image side. And a positive meniscus second lens element L2 having a convex surface facing the object side. Each of the first lens element L1 and the second lens element L2 has a high refractive index with respect to the d-line.

  In the zoom lens system according to Embodiment 2, the second lens group G2 includes, in order from the object side to the image side, a positive meniscus third lens element L3 with a convex surface facing the object side, and a convex surface facing the object side. The fourth lens element L4 having a negative meniscus shape, the fifth lens element L5 having a biconvex shape, and the sixth lens element L6 having a negative meniscus shape having a convex surface facing the image side. Among these, the third lens element L3 and the fourth lens element L4 are cemented, and the fifth lens element L5 and the sixth lens element L6 are cemented.

  In the zoom lens system according to Embodiment 2, the third lens unit G3 comprises solely a bi-convex seventh lens element L7.

  In the zoom lens system according to Embodiment 2, a parallel plate L8 is provided on the object side of the image plane S (between the image plane S and the seventh lens element L7).

  In the zoom lens system according to Embodiment 2, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus locus convex to the image side while changing the distance from the second lens group G2. The second lens group G2 moves to the object side, and the third lens group G3 moves to the image side.

  The zoom lens system according to Embodiment 2 includes a first lens element L1 having a concave surface on the image side and a negative power, and a convex surface on the object side, particularly constituting the first lens group G1, as shown later in Table 25. The refractive index of the second lens element L2 having positive power is high. By setting both the first lens element L1 and the second lens element L2 to have a high refractive index, the lens thickness in the optical axis direction of each lens element can be reduced and the curvature radius of the lens can be increased. Further, by reducing the refractive index difference between the lens elements, the Petzval sum can be easily controlled, so that field curvature can be corrected appropriately. In addition, aberration correction is possible without using a strong power surface with a small radius of curvature, so off-axis aberrations that are particularly problematic with zoom lens systems with a wide angle of view at the wide-angle end, especially distortion at the wide-angle end Astigmatism can be easily corrected.

  In the zoom lens system according to Embodiment 2, the second lens group G2 includes a first cemented lens element in which a third lens element L3 having positive power and a fourth lens element L4 having negative power are cemented. The second lens element is composed of a fifth lens element L5 having positive power and a sixth lens element L6 having negative power. As in the zoom lens system according to Embodiment 2, when the overall power is increased using a glass material having a high refractive index in the first lens group G1, the incident of the principal ray incident on the second lens group G2 Although the angle increases, the second lens group G2 adopts the above-described configuration, so that it is possible to appropriately correct off-axis aberration that occurs in such a case. Further, in the zoom lens system according to Embodiment 2, since the decentering error sensitivity of the first cemented lens element and the second cemented lens element is small, it is possible to allow a large error in incorporation of these lens elements. Therefore, the zoom lens system according to Embodiment 2 can realize a configuration that is easy to manufacture with little performance deterioration even when off-axis chief rays having a large incident angle are decentered. As in the zoom lens system according to Embodiment 2, it is desirable that the object side surface of the third lens element L3 is a convex surface and the image side surface of the fourth lens element L4 is a concave surface. With this configuration, the aberration generated on the convex surface can be canceled by the aberration generated on the concave surface, so that both the on-axis spherical aberration and the off-axis coma aberration can be corrected well.

  As shown in FIG. 7, in the zoom lens system according to Embodiment 3, the first lens group G1 is a negative meniscus first lens element L1 having a convex surface directed toward the object side in order from the object side to the image side. And a positive meniscus second lens element L2 having a convex surface facing the object side. Each of the first lens element L1 and the second lens element L2 has a high refractive index with respect to the d-line.

  In the zoom lens system according to Embodiment 3, the second lens unit G2 includes, in order from the object side to the image side, a biconvex third lens element L3, a biconcave fourth lens element L4, and an object It comprises a negative meniscus fifth lens element L5 with a convex surface facing the side, and a biconvex sixth lens element L6. Among these, the third lens element L3 and the fourth lens element L4 are cemented, and the fifth lens element L5 and the sixth lens element L6 are cemented.

  In the zoom lens system according to Embodiment 3, the third lens unit G3 comprises solely a bi-convex seventh lens element L7.

  In the zoom lens system according to Embodiment 3, a parallel plate L8 is provided on the object side of the image plane S (between the image plane S and the seventh lens element L7).

  In the zoom lens system according to Embodiment 3, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus locus convex toward the image side while changing the distance from the second lens group G2. The second lens group G2 moves to the object side, and the third lens group G3 moves to the image side.

  The zoom lens system according to Embodiment 3 includes a first lens element L1 having a concave surface on the image side and a negative power, and a convex surface on the object side, particularly constituting the first lens group G1, as shown later in Table 25. The refractive index of the second lens element L2 having positive power is high. By setting both the first lens element L1 and the second lens element L2 to have a high refractive index, the lens thickness in the optical axis direction of each lens element can be reduced and the curvature radius of the lens can be increased. Further, by reducing the refractive index difference between the lens elements, the Petzval sum can be easily controlled, so that field curvature can be corrected appropriately. In addition, aberration correction is possible without using a strong power surface with a small radius of curvature, so off-axis aberrations that are particularly problematic with zoom lens systems with a wide angle of view at the wide-angle end, especially distortion at the wide-angle end Astigmatism can be easily corrected.

  In the zoom lens system according to Embodiment 3, the second lens group G2 includes a first cemented lens element in which a third lens element L3 having positive power and a fourth lens element L4 having negative power are cemented. The second lens element is composed of a fifth lens element L5 having negative power and a sixth lens element L6 having positive power. When the entire power is increased by using a glass material having a high refractive index in the first lens group G1 as in the zoom lens system according to Embodiment 3, the incident of the principal ray incident on the second lens group G2 Although the angle increases, the second lens group G2 adopts the above-described configuration, so that it is possible to appropriately correct off-axis aberration that occurs in such a case. Further, in the zoom lens system according to Embodiment 3, since the decentering error sensitivity of the first cemented lens element and the second cemented lens element is small, it is possible to allow a large error in incorporation of these lens elements. Therefore, the zoom lens system according to Embodiment 3 can realize a configuration that is easy to manufacture with little performance deterioration even when off-axis chief rays having a large incident angle are decentered. As in the zoom lens system according to Embodiment 3, it is desirable that the object side surface of the third lens element L3 is a convex surface and the image side surface of the fourth lens element L4 is a concave surface. With this configuration, the aberration generated on the convex surface can be canceled by the aberration generated on the concave surface, so that both the on-axis spherical aberration and the off-axis coma aberration can be corrected well.

  As shown in FIG. 10, in the zoom lens system according to Embodiment 4, the first lens unit G1 includes, in order from the object side to the image side, a negative meniscus first lens element L1 having a convex surface directed toward the object side. And a positive meniscus second lens element L2 having a convex surface facing the object side. Each of the first lens element L1 and the second lens element L2 has a high refractive index with respect to the d-line.

  In the zoom lens system according to Embodiment 4, the second lens group G2 includes, in order from the object side to the image side, a biconvex third lens element L3, a biconcave fourth lens element L4, and an object It comprises a negative meniscus fifth lens element L5 with a convex surface facing the side, and a biconvex sixth lens element L6. Among these, the third lens element L3 and the fourth lens element L4 are cemented, and the fifth lens element L5 and the sixth lens element L6 are cemented.

  In the zoom lens system according to Embodiment 4, the third lens unit G3 comprises solely a bi-convex seventh lens element L7.

  In the zoom lens system according to Embodiment 4, a parallel plate L8 is provided on the object side of the image plane S (between the image plane S and the seventh lens element L7).

  In the zoom lens system according to Embodiment 4, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus locus convex to the image side while changing the distance from the second lens group G2. The second lens group G2 moves to the object side, and the third lens group G3 moves to the image side.

  The zoom lens system according to Embodiment 4 includes a first lens element L1 having a concave surface on the image side and having negative power, and a convex surface on the object side, particularly constituting the first lens group G1, as shown later in Table 25. The refractive index of the second lens element L2 having positive power is high. By setting both the first lens element L1 and the second lens element L2 to have a high refractive index, the lens thickness in the optical axis direction of each lens element can be reduced and the curvature radius of the lens can be increased. Further, by reducing the refractive index difference between the lens elements, the Petzval sum can be easily controlled, so that field curvature can be corrected appropriately. In addition, aberration correction is possible without using a strong power surface with a small radius of curvature, so off-axis aberrations that are particularly problematic with zoom lens systems with a wide angle of view at the wide-angle end, especially distortion at the wide-angle end Astigmatism can be easily corrected.

  In the zoom lens system according to Embodiment 4, the second lens group G2 includes a first cemented lens element in which a third lens element L3 having positive power and a fourth lens element L4 having negative power are cemented. The second lens element is composed of a fifth lens element L5 having negative power and a sixth lens element L6 having positive power. As in the zoom lens system according to Embodiment 4, when the overall power is increased by using a glass material having a high refractive index in the first lens group G1, the incident of the principal ray incident on the second lens group G2 Although the angle increases, the second lens group G2 adopts the above-described configuration, so that it is possible to appropriately correct off-axis aberration that occurs in such a case. Furthermore, in the zoom lens system according to Embodiment 4, since the decentering error sensitivity of the first cemented lens element and the second cemented lens element is small, it is possible to allow a large error in the incorporation of these lens elements. Therefore, the zoom lens system according to Embodiment 4 can realize a configuration that is easy to manufacture with little performance deterioration even when off-axis chief rays having a large incident angle are decentered. As in the zoom lens system according to Embodiment 4, it is desirable that the object side surface of the third lens element L3 is a convex surface and the image side surface of the fourth lens element L4 is a concave surface. With this configuration, the aberration generated on the convex surface can be canceled by the aberration generated on the concave surface, so that both the on-axis spherical aberration and the off-axis coma aberration can be corrected well.

  As shown in FIG. 13, in the zoom lens system according to Embodiment 5, the first lens unit G1 includes, in order from the object side to the image side, a negative meniscus first lens element L1 having a convex surface directed toward the object side. And a positive meniscus second lens element L2 having a convex surface facing the object side. Each of the first lens element L1 and the second lens element L2 has a high refractive index with respect to the d-line.

  In the zoom lens system according to Embodiment 5, the second lens group G2 includes, in order from the object side to the image side, a biconvex third lens element L3, a biconcave fourth lens element L4, and an object It comprises a negative meniscus fifth lens element L5 with a convex surface facing the side, and a biconvex sixth lens element L6. Among these, the third lens element L3 and the fourth lens element L4 are cemented, and the fifth lens element L5 and the sixth lens element L6 are cemented.

  In the zoom lens system according to Embodiment 5, the third lens unit G3 comprises solely a bi-convex seventh lens element L7.

  In the zoom lens system according to Embodiment 5, a parallel plate L8 is provided on the object side of the image plane S (between the image plane S and the seventh lens element L7).

  In the zoom lens system according to Embodiment 5, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus locus convex on the image side while changing the distance from the second lens group G2. The second lens group G2 moves to the object side, and the third lens group G3 moves to the image side.

  The zoom lens system according to Embodiment 5 includes a first lens element L1 having a concave surface on the image side and having negative power, and a convex surface on the object side, particularly constituting the first lens group G1, as shown later in Table 25. The refractive index of the second lens element L2 having positive power is high. By setting both the first lens element L1 and the second lens element L2 to have a high refractive index, the lens thickness in the optical axis direction of each lens element can be reduced and the curvature radius of the lens can be increased. Further, by reducing the refractive index difference between the lens elements, the Petzval sum can be easily controlled, so that field curvature can be corrected appropriately. In addition, aberration correction is possible without using a strong power surface with a small radius of curvature, so off-axis aberrations that are particularly problematic with zoom lens systems with a wide angle of view at the wide-angle end, especially distortion at the wide-angle end Astigmatism can be easily corrected.

  In the zoom lens system according to Embodiment 5, the second lens group G2 includes a first cemented lens element in which a third lens element L3 having positive power and a fourth lens element L4 having negative power are cemented. The second lens element is composed of a fifth lens element L5 having negative power and a sixth lens element L6 having positive power. As in the zoom lens system according to Embodiment 5, when the overall power is increased using a glass material having a high refractive index in the first lens group G1, the incident of the principal ray incident on the second lens group G2 Although the angle increases, the second lens group G2 adopts the above-described configuration, so that it is possible to appropriately correct off-axis aberration that occurs in such a case. Further, in the zoom lens system according to Embodiment 5, since the decentering error sensitivity of the first cemented lens element and the second cemented lens element is small, it is possible to allow a large error in incorporation of these lens elements. Therefore, the zoom lens system according to Embodiment 5 can realize a configuration that is easy to manufacture with little performance deterioration even when off-axis chief rays having a large incident angle are decentered. As in the zoom lens system according to Embodiment 5, it is desirable that the object side surface of the third lens element L3 is a convex surface and the image side surface of the fourth lens element L4 is a concave surface. With this configuration, the aberration generated on the convex surface can be canceled by the aberration generated on the concave surface, so that both the on-axis spherical aberration and the off-axis coma aberration can be corrected well.

  As shown in FIG. 16, in the zoom lens system according to Embodiment 6, the first lens unit G1 includes, in order from the object side to the image side, a negative meniscus first lens element L1 having a convex surface directed toward the object side. And a positive meniscus second lens element L2 having a convex surface facing the object side. Each of the first lens element L1 and the second lens element L2 has a high refractive index with respect to the d-line.

  In the zoom lens system according to Embodiment 6, the second lens group G2 includes, in order from the object side to the image side, a positive meniscus third lens element L3 with a convex surface facing the object side, and a convex surface facing the object side. The fourth lens element L4 having a negative meniscus shape, the fifth lens element L5 having a biconvex shape, and the sixth lens element L6 having a negative meniscus shape having a convex surface facing the image side. Among these, the third lens element L3 and the fourth lens element L4 are cemented, and the fifth lens element L5 and the sixth lens element L6 are cemented.

  In the zoom lens system according to Embodiment 6, the third lens unit G3 comprises solely a bi-convex seventh lens element L7.

  In the zoom lens system according to Embodiment 6, a parallel plate L8 is provided on the object side of the image plane S (between the image plane S and the seventh lens element L7).

  In the zoom lens system according to Embodiment 6, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus locus convex to the image side while changing the distance from the second lens group G2. The second lens group G2 moves to the object side, and the third lens group G3 moves to the image side.

  The zoom lens system according to Embodiment 6 includes a first lens element L1 having a concave surface on the image side and a negative power, and a convex surface on the object side, particularly constituting the first lens group G1, as shown later in Table 25. The refractive index of the second lens element L2 having positive power is high. By setting both the first lens element L1 and the second lens element L2 to have a high refractive index, the lens thickness in the optical axis direction of each lens element can be reduced and the curvature radius of the lens can be increased. Further, by reducing the refractive index difference between the lens elements, the Petzval sum can be easily controlled, so that field curvature can be corrected appropriately. In addition, aberration correction is possible without using a strong power surface with a small radius of curvature, so off-axis aberrations that are particularly problematic with zoom lens systems with a wide angle of view at the wide-angle end, especially distortion at the wide-angle end Astigmatism can be easily corrected.

  In the zoom lens system according to Embodiment 6, the second lens group G2 includes a first cemented lens element in which a third lens element L3 having positive power and a fourth lens element L4 having negative power are cemented. The second lens element is composed of a fifth lens element L5 having positive power and a sixth lens element L6 having negative power. As in the zoom lens system according to Embodiment 6, when the entire power is increased using a glass material having a high refractive index in the first lens group G1, the incident of the principal ray incident on the second lens group G2 Although the angle increases, the second lens group G2 adopts the above-described configuration, so that it is possible to appropriately correct off-axis aberration that occurs in such a case. Further, in the zoom lens system according to Embodiment 6, since the decentering error sensitivity of the first cemented lens element and the second cemented lens element is small, it is possible to allow a large error in incorporation of these lens elements. Therefore, the zoom lens system according to Embodiment 6 can realize a configuration that is easy to manufacture with little performance deterioration even when off-axis chief rays having a large incident angle are decentered. As in the zoom lens system according to Embodiment 6, it is desirable that the object side surface of the third lens element L3 is a convex surface and the image side surface of the fourth lens element L4 is a concave surface. With this configuration, the aberration generated on the convex surface can be canceled by the aberration generated on the concave surface, so that both the on-axis spherical aberration and the off-axis coma aberration can be corrected well.

  As shown in FIG. 19, in the zoom lens system according to Embodiment 7, the first lens unit G1 includes, in order from the object side to the image side, a negative meniscus first lens element L1 having a convex surface directed toward the object side. And a positive meniscus second lens element L2 having a convex surface facing the object side. Each of the first lens element L1 and the second lens element L2 has a high refractive index with respect to the d-line.

  In the zoom lens system according to Embodiment 7, the second lens unit G2 includes, in order from the object side to the image side, a positive meniscus third lens element L3 with a convex surface facing the object side, and a convex surface facing the object side. The fourth lens element L4 having a negative meniscus shape, the fifth lens element L5 having a biconvex shape, and the sixth lens element L6 having a negative meniscus shape having a convex surface facing the image side. Among these, the third lens element L3 and the fourth lens element L4 are cemented, and the fifth lens element L5 and the sixth lens element L6 are cemented.

  In the zoom lens system according to Embodiment 7, the third lens unit G3 comprises solely a bi-convex seventh lens element L7.

  In the zoom lens system according to Embodiment 7, a parallel plate L8 is provided on the object side of the image plane S (between the image plane S and the seventh lens element L7).

  In the zoom lens system according to Embodiment 7, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus locus convex to the image side while changing the distance from the second lens group G2. The second lens group G2 moves to the object side, and the third lens group G3 moves to the image side.

  The zoom lens system according to Embodiment 7 includes a first lens element L1 having a concave surface on the image side and a negative power, and a convex surface on the object side, particularly constituting the first lens group G1, as shown later in Table 25. The refractive index of the second lens element L2 having positive power is high. By setting both the first lens element L1 and the second lens element L2 to have a high refractive index, the lens thickness in the optical axis direction of each lens element can be reduced and the curvature radius of the lens can be increased. Further, by reducing the refractive index difference between the lens elements, the Petzval sum can be easily controlled, so that field curvature can be corrected appropriately. In addition, aberration correction is possible without using a strong power surface with a small radius of curvature, so off-axis aberrations that are particularly problematic with zoom lens systems with a wide angle of view at the wide-angle end, especially distortion at the wide-angle end Astigmatism can be easily corrected.

  In the zoom lens system according to Embodiment 7, the second lens group G2 includes a first cemented lens element in which a third lens element L3 having positive power and a fourth lens element L4 having negative power are cemented. The second lens element is composed of a fifth lens element L5 having positive power and a sixth lens element L6 having negative power. As in the zoom lens system according to Embodiment 7, when the entire power is increased using a glass material having a high refractive index in the first lens group G1, the incident of the principal ray incident on the second lens group G2 Although the angle increases, the second lens group G2 adopts the above-described configuration, so that it is possible to appropriately correct off-axis aberration that occurs in such a case. Further, in the zoom lens system according to Embodiment 7, since the decentering error sensitivity of the first cemented lens element and the second cemented lens element is small, it is possible to allow a large error in incorporation of these lens elements. Therefore, the zoom lens system according to Embodiment 7 can realize a configuration that is easy to manufacture with little performance deterioration even when off-axis chief rays having a large incident angle are decentered. As in the zoom lens system according to Embodiment 7, it is desirable that the object side surface of the third lens element L3 be a convex surface and the image side surface of the fourth lens element L4 be a concave surface. With this configuration, the aberration generated on the convex surface can be canceled by the aberration generated on the concave surface, so that both the on-axis spherical aberration and the off-axis coma aberration can be corrected well.

  As shown in FIG. 22, in the zoom lens system according to Embodiment 8, the first lens unit G1 includes, in order from the object side to the image side, a negative meniscus first lens element L1 with a convex surface directed toward the object side. And a positive meniscus second lens element L2 having a convex surface facing the object side. Each of the first lens element L1 and the second lens element L2 has a high refractive index with respect to the d-line.

  In the zoom lens system according to Embodiment 8, the second lens group G2 includes, in order from the object side to the image side, a biconvex third lens element L3, a biconcave fourth lens element L4, and an object It comprises a negative meniscus fifth lens element L5 with a convex surface facing the side, and a biconvex sixth lens element L6. Among these, the third lens element L3 and the fourth lens element L4 are cemented, and the fifth lens element L5 and the sixth lens element L6 are cemented.

  In the zoom lens system according to Embodiment 8, the third lens unit G3 comprises solely a bi-convex seventh lens element L7.

  In the zoom lens system according to Embodiment 8, a parallel plate L8 is provided on the object side of the image plane S (between the image plane S and the seventh lens element L7).

  In the zoom lens system according to Embodiment 8, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a locus locus convex on the image side while changing the distance from the second lens group G2. The second lens group G2 moves to the object side, and the third lens group G3 moves to the image side.

  The zoom lens system according to Embodiment 8 includes a first lens element L1 having a concave surface on the image side and having negative power, and a convex surface on the object side, particularly constituting the first lens group G1, as shown in Table 25 later. The refractive index of the second lens element L2 having positive power is high. By setting both the first lens element L1 and the second lens element L2 to have a high refractive index, the lens thickness in the optical axis direction of each lens element can be reduced and the curvature radius of the lens can be increased. Further, by reducing the refractive index difference between the lens elements, the Petzval sum can be easily controlled, so that field curvature can be corrected appropriately. In addition, aberration correction is possible without using a strong power surface with a small radius of curvature, so off-axis aberrations that are particularly problematic with zoom lens systems with a wide angle of view at the wide-angle end, especially distortion at the wide-angle end Astigmatism can be easily corrected.

  In the zoom lens system according to Embodiment 8, the second lens group G2 includes a first cemented lens element in which a third lens element L3 having positive power and a fourth lens element L4 having negative power are cemented. The second lens element is composed of a fifth lens element L5 having negative power and a sixth lens element L6 having positive power. As in the zoom lens system according to Embodiment 8, when the entire power is increased using a glass material having a high refractive index in the first lens group G1, the incident of the principal ray incident on the second lens group G2 Although the angle increases, the second lens group G2 adopts the above-described configuration, so that it is possible to appropriately correct off-axis aberration that occurs in such a case. Further, in the zoom lens system according to Embodiment 8, since the decentering error sensitivity of the first cemented lens element and the second cemented lens element is small, it is possible to allow a large error in assembling these lens elements. Therefore, the zoom lens system according to Embodiment 8 can realize a structure that is easy to manufacture with little performance deterioration even when off-axis chief rays having a large incident angle are decentered. Further, as in the zoom lens system according to Embodiment 8, it is desirable that the object side surface of the third lens element L3 be a convex surface and the image side surface of the fourth lens element L4 be a concave surface. With this configuration, the aberration generated on the convex surface can be canceled by the aberration generated on the concave surface, so that both the on-axis spherical aberration and the off-axis coma aberration can be corrected well.

  In the zoom lens system according to each embodiment, during zooming from the wide-angle end to the telephoto end, the first lens group G1, the second lens group G2, and the third lens group G3 all move along the optical axis. Of the lens groups, for example, the second lens group G2 is moved in a direction perpendicular to the optical axis, whereby image blur due to camera shake, vibration, or the like can be optically corrected.

  In the present invention, when the image blur is optically corrected, the second lens unit moves in the direction perpendicular to the optical axis in this way, thereby suppressing an increase in the size of the entire zoom lens system and a compact configuration. However, it is possible to correct image blur while maintaining excellent imaging characteristics with small decentration coma and decentering astigmatism.

  The following description is given for conditions preferred to be satisfied by a zoom lens system having the above basic configuration like the zoom lens systems according to Embodiments 1 to 8. A plurality of preferable conditions are defined for the zoom lens system according to each embodiment, but a zoom lens system configuration that satisfies all of the plurality of conditions is most desirable. However, by satisfying individual conditions, it is possible to obtain a zoom lens system that exhibits the corresponding effects.

All conditions described below are satisfied only under the following two preconditions (A) and (B) unless otherwise specified.
3.2 <f _T / f _W (A)
ω _W > 35 (B)
here,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end.

In addition, the said conditions (B) can express the effect of each condition shown below more notably by setting it as the following conditions (B) '.
ω _W > 38 (B) '

The zoom lens system having the basic configuration satisfies the following condition (1).
5.0 <αi _W <20.0 (1)
here,
αi _W : Image sensor incident angle of the chief ray at the maximum image height at the wide-angle end (positive when the chief ray is incident on the light receiving surface of the image sensor while separating from the optical axis)
It is.

  Condition (1) is a condition for defining the image sensor incident angle of the principal ray at the maximum image height at the wide-angle end. By satisfying the condition (1), the incidence angle of the most off-axis chief ray incident on the image sensor is reduced, so that the influence of shading is reduced. If the upper limit of condition (1) is exceeded, the amount of peripheral light decreases due to the shading of the image sensor. On the contrary, if the lower limit of the condition (1) is not reached, the angle of the negative most off-axis principal ray at the telephoto end becomes large at the time of zooming, and the peripheral light quantity at the telephoto end is particularly reduced.

Furthermore, by satisfying the following condition (1) ′, the change in the incident angle of the chief ray at the maximum image height during zooming is suppressed, so that fluctuations in the amount of peripheral light are also suppressed, which is particularly effective. is there.
αi _W <15.0 (1) '

In addition, the zoom lens system having the basic configuration satisfies the following condition (2) simultaneously with the condition (1).
(N ₁₁ −1) · (n ₁₂ −1) ≧ 0.84 (2)
here,
n ₁₁ : refractive index with respect to d-line of the first lens element,
n ₁₂ is the refractive index of the second lens element with respect to the d-line.

  Condition (2) is a condition that defines the refractive indexes of the first lens element and the second lens element. By satisfying the condition (2), the lens thickness in the optical axis direction of each lens element can be reduced and the curvature radius of the lens can be increased. Further, by satisfying the condition (2), the Petzval sum can be easily controlled by reducing the refractive index difference between the lens elements. Therefore, the zoom lens system having the basic configuration is adjusted so as not to exceed the range of the condition (2). The first lens element satisfies the above condition (2) and the image side surface is aspherical. The second lens element satisfies the above condition (2) and the object side surface is aspherical. It is desirable. Thus, by making the opposing surfaces of the first lens element and the second lens element both aspherical surfaces, it is effective in correcting off-axis aberrations, particularly distortion and astigmatism at the wide-angle end.

For example, as in the zoom lens systems according to Embodiments 1 to 8, it is preferable that the zoom lens system having the basic configuration as described above satisfies the following condition (5).
_{0.1 <(n 11 -1) ·} (n 12 -1) · d · f W / (r 12 · r 21) <0.3
... (5)
here,
n ₁₁ : refractive index with respect to d-line of the first lens element,
n ₁₂ : refractive index with respect to d-line of the second lens element,
r ₁₂ : radius of curvature of the image side surface of the first lens element,
r ₂₁ : radius of curvature of the object side surface of the second lens element,
d: optical axis upper surface distance between the image side surface of the first lens element and the object side surface of the second lens element;
f _W : the focal length of the entire system at the wide angle end.

  Condition (5) is a condition that satisfies the first lens element and the second lens element in the first lens group. Exceeding the upper limit of the condition (5) is not desirable because the thickness along the optical axis of the first lens group increases and it becomes difficult to shorten the total length when retracted. If the upper limit of condition (5) is exceeded, correction of various aberrations for off-axis light, particularly astigmatism and distortion at the wide-angle end, will be insufficient, which is not desirable. On the other hand, if the lower limit of the condition (5) is not reached, it is difficult to correct various aberrations for off-axis light, particularly astigmatism and distortion at the wide angle end, which is not desirable.

The above effect can be further enhanced by further satisfying at least one of the following conditions (5) ′ and (5) ″.
_{0.15 <(n 11 -1) ·} (n 12 -1) · d · f W / (r 12 · r 21)
... (5) '
(N ₁₁ -1) · (n ₁₂ -1) · d · f _W / (r ₁₂ · r ₂₁ ) <0.25
... (5) ''

For example, the zoom lens system having the basic configuration as described above like the zoom lens systems according to Embodiments 1 to 8 desirably satisfies the following condition (6).
0.0001 <(n ₁₁ −1) · (n ₁₂ −1) · d ² · f _T / (r ₁₂ · r ₂₁ · f _W )
<0.04 (6)
here,
n ₁₁ : refractive index with respect to d-line of the first lens element,
n ₁₂ : refractive index with respect to d-line of the second lens element,
r ₁₂ : radius of curvature of the image side surface of the first lens element,
r ₂₁ : radius of curvature of the object side surface of the second lens element,
d: optical axis upper surface distance between the image side surface of the first lens element and the object side surface of the second lens element;
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end.

  Condition (6) is a condition that the first lens element and the second lens element in the first lens group are satisfied. If the upper limit of condition (6) is exceeded, the thickness along the optical axis of the first lens group becomes large, and it is difficult to shorten the total length when retracted, which is not desirable. If the upper limit of condition (6) is exceeded, correction of various aberrations for off-axis light, particularly astigmatism and distortion at the wide-angle end, will be insufficient, which is not desirable. On the other hand, if the value goes below the lower limit of the condition (6), it is difficult to correct various aberrations for off-axis light, particularly astigmatism and distortion at the wide-angle end.

For example, the zoom lens system having the basic configuration as described above like the zoom lens systems according to Embodiments 1 to 8 desirably satisfies the following condition (7).
1.0 <(r ₁₂ + r ₂₁ ) / (r ₁₂ −r ₂₁ ) <2.5 (7)
here,
r ₁₂ : radius of curvature of the image side surface of the first lens element,
r ₂₁ is the radius of curvature of the object side surface of the second lens element.

  Condition (7) is a condition that defines the SF (shape factor) of the air lens formed in the first lens group. If the upper limit of condition (7) is exceeded, correction of various aberrations for off-axis light, particularly astigmatism and distortion at the wide-angle end, will be insufficient, which is not desirable. On the other hand, if the value is below the lower limit of the condition (7), the power on the image side surface of the first lens element becomes particularly strong and the manufacturing becomes difficult, which is not desirable.

In addition, the said effect can be improved further by satisfying the following conditions (7) '.
1.2 <(r ₁₂ + r ₂₁ ) / (r ₁₂ −r ₂₁ ) (7) ′

For example, the zoom lens system having the basic configuration as described above like the zoom lens systems according to Embodiments 1 to 8 desirably satisfies the following condition (8).
0.5 <| f _AIR | / f _W <1.1 (8)
here,
f _AIR : Focal length of the air lens formed between the image side surface of the first lens element and the object side surface of the second lens element,
f _W : the focal length of the entire system at the wide angle end.

  Condition (8) is a condition that defines the focal length of the air lens formed in the first lens group. If the upper limit of condition (8) is exceeded, correction of various aberrations for off-axis light, particularly astigmatism and distortion at the wide-angle end, will be insufficient, which is not desirable. On the other hand, if the value is below the lower limit of the condition (8), the power on the image side surface of the first lens element becomes particularly strong and difficult to manufacture.

In addition, the above effect can be further enhanced by further satisfying the following condition (8) ′.
0.7 <| f _AIR | / f _W (8) '

For example, as in the zoom lens systems according to Embodiments 1 to 8, it is preferable that the zoom lens system having the basic configuration as described above satisfies the following condition (9).
2.4 <| f _G1 | / f _W <4.0 (9)
here,
f _G1 : composite focal length of the first lens group,
f _W : the focal length of the entire system at the wide angle end.

  Condition (9) is a condition that defines the focal length of the first lens group. If the upper limit of the condition (9) is exceeded, the power of the first lens group becomes too weak, and correction of various aberrations with respect to off-axis light, particularly astigmatism and distortion at the wide angle end, becomes insufficient. Since the effective diameter of the lens group is increased, it is difficult to reduce the size particularly in the direction perpendicular to the optical axis, which is not desirable. Conversely, if the lower limit of the condition (9) is not reached, the power of the first lens group becomes too strong, and the decentration error sensitivity between the first lens element and the second lens element in the first lens group becomes high, This is not desirable because the performance deterioration due to eccentricity becomes remarkable and the manufacture becomes difficult. If the lower limit of the condition (9) is not reached, the lateral chromatic aberration generated in the first lens group becomes too large, which is not desirable.

In addition, the above effect can be further enhanced by further satisfying the following condition (9) ′.
| F _G1 | / f _W <3.0 (9) ′

For example, the zoom lens system having the basic configuration as described above like the zoom lens systems according to Embodiments 1 to 8 desirably satisfies the following condition (10).
1.85 <f _G2 / f _W <3.0 (10)
here,
f _G2 : Composite focal length of the second lens group,
f _W : the focal length of the entire system at the wide angle end.

  Condition (10) is a condition that defines the focal length of the second lens group. If the upper limit of condition (10) is exceeded, the amount of movement of the second lens unit becomes too large during zooming, which makes it difficult to reduce the size of the zoom lens system, which is not desirable. On the other hand, if the lower limit of condition (10) is not reached, the focal length of the second lens group becomes too short, which makes it difficult to correct aberrations in the entire zoom range, which is not desirable.

In addition, when the following conditions (10) ′ and (10) ″ are further satisfied, the above effect can be further enhanced.
1.9 <f _G2 / f _W (10) ′
1.95 <f _G2 / f _W (10) ''

For example, the zoom lens system having the basic configuration as described above like the zoom lens systems according to Embodiments 1 to 8 desirably satisfies the following condition (11).
2.5 <f _G3 / f _W <6.0 (11)
here,
f _G3 : composite focal length of the third lens group,
f _W : the focal length of the entire system at the wide angle end.

  Condition (11) is a condition that defines the focal length of the third lens group. If the upper limit of condition (11) is exceeded, the power of the third lens group becomes small, the amount of movement of the third lens group becomes large, and it becomes difficult to downsize the optical system, which is not desirable. On the contrary, if the lower limit of the condition (11) is not reached, the power of the third lens group becomes large, and it becomes difficult to correct spherical aberration and coma aberration in the variable power range where the third lens group is relatively close to the object side. Therefore, it is not desirable.

Furthermore, the above effect can be further enhanced by satisfying any of the following conditions (11) ′ and (11) ″.
3.0 <f _G3 / f _W (11) ′
4.0 <f _G3 / f _W (11) ''

For example, the zoom lens system having the basic configuration as described above like the zoom lens systems according to Embodiments 1 to 8 desirably satisfies the following condition (12).
1.0 <| f _L1 | / f _W <2.5 (12)
here,
f _L1 : focal length of the first lens element,
f _W : the focal length of the entire system at the wide angle end.

  Condition (12) is a condition that defines the focal length of the first lens element. If the upper limit of the condition (12) is exceeded, correction of various aberrations with respect to off-axis light, particularly astigmatism and distortion at the wide-angle end becomes insufficient, which is not desirable. On the other hand, if the lower limit of the condition (12) is not reached, it is necessary to increase the positive power of the second lens element constituting the first lens group, which makes it difficult to correct the aberration generated in the first lens group. Is not desirable.

Furthermore, the above effect can be further enhanced by satisfying at least one of the following conditions (12) ′ and (12) ″.
1.1 <| f _L1 | / f _W (12) ′
| F _L1 | / f _W <1.6 (12) ''

For example, the zoom lens system having the basic configuration as described above like the zoom lens systems according to Embodiments 1 to 8 desirably satisfies the following condition (13).
2.0 <f _L2 / f _W <5.0 (13)
here,
f _L2 : focal length of the second lens element,
f _W : the focal length of the entire system at the wide angle end.

  Condition (13) is a condition that defines the focal length of the second lens element. Exceeding the upper limit of the condition (13) is not desirable because the Petzval sum becomes too large to increase the field curvature and the astigmatism becomes too large. Conversely, if the lower limit of the condition (13) is not reached, the negative power of the entire first lens group becomes weak, which makes it difficult to reduce the size of the zoom lens system, which is not desirable.

Furthermore, the above effect can be further enhanced by satisfying at least one of the following conditions (13) ′ and (13) ″.
2.4 <f _L2 / f _W (13) ′
f _L2 / f _W <4.0 (13) ''

For example, the zoom lens system having the basic configuration as described above like the zoom lens systems according to Embodiments 1 to 8 desirably satisfies the following condition (14).
0.4 <| f _L1 | / | f _G1 | <0.8 (14)
here,
f _L1 : focal length of the first lens element,
f _G1 is the combined focal length of the first lens group.

  Condition (14) is a condition that defines the focal length of the first lens element. If the upper limit of condition (14) is exceeded, correction of various aberrations for off-axis light, particularly astigmatism and distortion at the wide-angle end, will be insufficient, which is not desirable. On the contrary, if the lower limit of the condition (14) is not reached, it is necessary to increase the positive power of the second lens element constituting the first lens group, and it becomes difficult to correct the aberration generated in the first lens group. Is not desirable.

Furthermore, the above-mentioned effect can be further enhanced by satisfying any of the following conditions (14) ′ and (14) ″.
0.45 <| f _L1 | / | f _G1 | (14) ′
0.55 <| f _L1 | / | f _G1 | (14) ''

For example, the zoom lens system having the basic configuration as described above like the zoom lens systems according to Embodiments 1 to 8 desirably satisfies the following condition (15).
0.85 <f _L2 / | f _G1 | <2.0 (15)
here,
f _L2 : focal length of the second lens element,
f _G1 is the combined focal length of the first lens group.

  Condition (15) is a condition that defines the focal length of the second lens element. Exceeding the upper limit of condition (15) is not desirable because the Petzval sum becomes too large and field curvature increases and astigmatism becomes too large. On the other hand, if the lower limit of the condition (15) is not reached, the negative power of the entire first lens group becomes weak, which makes it difficult to reduce the size of the zoom lens system, which is not desirable.

In addition, the above effect can be further enhanced by further satisfying the following condition (15) ′.
f _L2 / | f _G1 | <1.8 (15) ′

For example, as in the zoom lens systems according to Embodiments 1 to 8, it is preferable that the zoom lens system having the basic configuration as described above satisfies the following condition (16).
1.9 <f _L2 / | f _L1 | <3.0 (16)
here,
f _L1 : focal length of the first lens element,
f _L2 is the focal length of the second lens element.

  The condition (16) is a condition that defines a focal length ratio between the first lens element and the second lens element. Exceeding the upper limit of the condition (16) is not desirable because the power balance between the first lens element and the second lens element deteriorates, and the field curvature and distortion become large. On the other hand, if the lower limit of the condition (16) is not reached, similarly, the balance of power between the first lens element and the second lens element is deteriorated, distortion is generated, and the effective diameter of the first lens element is reduced. Is undesirably large because it is difficult to reduce the size particularly in the direction perpendicular to the optical axis.

Note that the above-described effect can be further enhanced by further satisfying the following condition (16) ′.
2.0 <f _L2 / | f _L1 | (16) ′

  Each lens group constituting the zoom lens system according to each embodiment includes a refractive lens that deflects incident light by refraction (that is, a type in which deflection is performed at an interface between media having different refractive indexes). Lens), but the type of lens 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.

  In each embodiment, the optical path may be bent before, after, or during the zoom lens system by disposing the reflecting surface in the optical path. The folding position may be set as necessary, and the apparent thinning of the camera can be achieved by appropriately bending the optical path.

  Furthermore, in each of the embodiments, a configuration in which a parallel plate such as an optical low-pass filter is disposed between the final surface of the zoom lens system (the most image side surface of the third lens group) and the image sensor S has been described. Examples of the low-pass filter include a birefringence low-pass filter made of quartz crystal whose direction of a predetermined crystal axis is adjusted, and a phase-type low-pass filter that achieves a required optical cutoff frequency characteristic by a diffraction effect. Applicable.

(Embodiment 9)
FIG. 25 is a schematic configuration diagram of a digital still camera according to the ninth embodiment. In FIG. 25, the digital still camera includes an image pickup apparatus including a zoom lens system 1 and an image pickup device 2 that is a CCD, a liquid crystal monitor 3, and a housing 4. As the zoom lens system 1, the zoom lens system according to Embodiment 1 is used. In FIG. 25, the zoom lens system 1 includes a first lens group G1, a diaphragm A, a second lens group G2, and a third lens group G3. In the housing 4, the zoom lens system 1 is disposed on the front side, and the imaging element 2 is disposed on the rear side of the zoom lens system 1. A liquid crystal monitor 3 is disposed on the rear side of the housing 4, and an optical image of the subject by the zoom lens system 1 is formed on the image plane S.

  The lens barrel includes a main lens barrel 5, a movable lens barrel 6, and a cylindrical cam 7. When the cylindrical cam 7 is rotated, the first lens group G1, the second lens group G2, and the third lens group G3 are moved to predetermined positions with reference to the image sensor 2, and the zooming from the wide angle end to the telephoto end is performed. It can be carried out. The third lens group G3 is movable in the optical axis direction by a focus adjustment motor.

  Thus, by using the zoom lens system according to Embodiment 1 for a digital still camera, it is possible to provide a small digital still camera that has a high ability to correct resolution and curvature of field and has a short optical total length when not in use. it can. In the digital still camera shown in FIG. 25, any of the zoom lens systems according to Embodiments 2 to 8 may be used instead of the zoom lens system according to Embodiment 1. Further, the optical system of the digital still camera shown in FIG. 25 can also be used for a digital video camera for moving images. In this case, not only a still image but also a moving image with high resolution can be taken.

  In addition, an imaging apparatus including the zoom lens system according to Embodiments 1 to 8 described above and an imaging element such as a CCD or a CMOS is used as a monitoring camera in a mobile phone device, a PDA (Personal Digital Assistance), or a monitoring system. It can also be applied to Web cameras, in-vehicle cameras, and the like.

ここで、κは円錐定数、Ａ４、Ａ６、Ａ８、Ａ１０、Ａ１２及びＡ１４は、それぞれ４次、６次、８次、１０次、１２次及び１４次の非球面係数である。 Hereinafter, numerical examples in which the zoom lens systems according to Embodiments 1 to 8 are specifically implemented will be described. In each numerical example, the unit of length in the table is “mm”, and the unit of angle of view is “°”. In each numerical example, r is a radius of curvature, d is a surface interval, nd is a refractive index with respect to the d line, and vd is an Abbe number with respect to the d line. In each numerical example, the surface marked with * is an aspherical surface, and the aspherical shape is defined by the following equation.

Here, κ is a conic constant, and A4, A6, A8, A10, A12, and A14 are fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, and fourteenth-order aspheric coefficients, respectively.

  FIG. 2 is a longitudinal aberration diagram of the zoom lens system according to Example 1. FIG. FIG. 5 is a longitudinal aberration diagram of the zoom lens system according to Example 2. FIG. FIG. 8 is a longitudinal aberration diagram of the zoom lens system according to Example 3. FIG. 11 is a longitudinal aberration diagram of the zoom lens system according to Example 4; FIG. 14 is a longitudinal aberration diagram of the zoom lens system according to Example 5. FIG. 17 is a longitudinal aberration diagram of the zoom lens system according to Example 6; FIG. 20 is a longitudinal aberration diagram of the zoom lens system according to Example 7. 23 is a longitudinal aberration diagram of a zoom lens system according to Example 8. FIG.

  In each longitudinal aberration diagram, (a) shows the aberration at the wide angle end, (b) shows the intermediate position, and (c) shows the aberration at the telephoto end. Each longitudinal aberration diagram shows spherical aberration (SA (mm)), astigmatism (AST (mm)), and distortion (DIS (%)) in order from the left side. In the spherical aberration diagram, the vertical axis represents the F number (indicated by F in the figure), the solid line is the d line (d-line), the short broken line is the F line (F-line), and the long broken line is the C line (C- line). In the astigmatism diagram, the vertical axis represents the image height (indicated by H in the figure), the solid line represents the sagittal plane (indicated by s), and the broken line represents the meridional plane (indicated by m in the figure). is there. In the distortion diagram, the vertical axis represents the image height (indicated by H in the figure).

  FIG. 3 is a lateral aberration diagram at the telephoto end of the zoom lens system according to Example 1. FIG. 6 is a lateral aberration diagram at the telephoto end of the zoom lens system according to Example 2. FIG. FIG. 9 is a lateral aberration diagram at the telephoto end of the zoom lens system according to Example 3. FIG. 12 is a lateral aberration diagram at the telephoto end of the zoom lens system according to Example 4. FIG. 15 is a lateral aberration diagram at the telephoto end of the zoom lens system according to Example 5. FIGS. FIG. 18 is a lateral aberration diagram at the telephoto end of the zoom lens system according to Example 6; FIG. 21 is a lateral aberration diagram at the telephoto end of the zoom lens system according to Example 7. FIG. FIG. 24 is a lateral aberration diagram at the telephoto end of the zoom lens system according to Example 8. FIG.

  In each lateral aberration diagram, the upper three aberration diagrams show a basic state in which image blur correction is not performed at the telephoto end, and the lower three aberration diagrams move the entire second lens group G2 by a predetermined amount in a direction perpendicular to the optical axis. This corresponds to the image blur correction state at the telephoto end. Of the lateral aberration diagrams in the basic state, the upper row shows the lateral aberration at the image point of 70% of the maximum image height, the middle row shows the lateral aberration at the axial image point, and the lower row shows the lateral aberration at the image point of -70% of the maximum image height. Respectively. In each lateral aberration diagram in the image blur correction state, the upper row shows the lateral aberration at the image point of 70% of the maximum image height, the middle row shows the lateral aberration at the axial image point, and the lower row shows the image point at −70% of the maximum image height. Each corresponds to lateral aberration. In each lateral aberration diagram, the horizontal axis represents the distance from the principal ray on the pupil plane, the solid line is the d line (d-line), the short broken line is the F line (F-line), and the long broken line is the C line ( C-line) characteristics. In each lateral aberration diagram, the meridional plane is a plane including the optical axis of the first lens group G1 and the optical axis of the second lens group G2.

  In the image blur correction state, the amount of movement of the second lens group G2 in the direction perpendicular to the optical axis is 0.086 mm in Example 1, 0.086 mm in Example 2, and 0.086 mm in Example 3. 0.086 mm, Example 4 is 0.089 mm, Example 5 is 0.083 mm, Example 6 is 0.084 mm, Example 7 is 0.080 mm, and Example 8 is 0.085 mm. Note that when the shooting distance is ∞ and the zoom lens system is tilted by 0.6 ° at the telephoto end, the entire amount of the second lens group G2 is translated in the direction perpendicular to the optical axis by the above values. It is equal to the amount of image eccentricity when

  As can be seen from the respective lateral aberration diagrams, the symmetry of the lateral aberration at the axial image point is good. Further, when the lateral aberration at the + 70% image point and the lateral aberration at the -70% image point are compared in the basic state, the curvature is small and the inclinations of the aberration curves are almost equal. It can be seen that the aberration is small. This means that sufficient imaging performance is obtained even in the image blur correction state. When the image blur correction angle of the zoom lens system is the same, the amount of parallel movement required for image blur correction decreases as the focal length of the entire zoom lens system decreases. Accordingly, at any zoom position, it is possible to perform sufficient image blur correction without deteriorating the imaging characteristics for an image blur correction angle up to 0.6 °.

(Numerical example 1)
The zoom lens system of Numerical Example 1 corresponds to Embodiment 1 shown in FIG. Table 1 shows surface data of the zoom lens system of Numerical Example 1, Table 2 shows aspheric data, and Table 3 shows various data.

Table 1 (surface data)

Surface number rd nd vd
Object ∞ ∞
1 32.85931 1.00000 1.90000 34.5
2 * 5.24553 1.51470
3 * 8.11887 1.60000 2.14000 17.0
4 13.20028 Variable
5 (Aperture) ∞ 0.35000
6 * 4.51384 2.10000 1.80359 40.8
7 -22.03270 0.40000 1.80518 25.5
8 4.05898 0.47690
9 15.44748 1.14410 1.77250 49.6
10 -15.44748 0.40000 1.84666 23.8
11 -17.21651 Variable
12 * 34.99100 1.52000 1.66547 55.2
13 * -20.18062 variable
14 ∞ 0.78000 1.51680 64.2
15 ∞ Variable (BF)
Image plane ∞

Table 2 (Aspheric data)

Second side
K = -1.50410E + 00, A4 = 1.00500E-03, A6 = -3.77000E-05, A8 = 1.55100E-06
A10 = -1.04000E-08, A12 = -8.23000E-10, A14 = 1.45800E-11
Third side
K = 0.00000E + 00, A4 = 1.06800E-04, A6 = -2.41000E-05, A8 = 1.06600E-06
A10 = -1.34000E-08, A12 = -3.81000E-10, A14 = 8.46200E-12
6th page
K = -2.06055E-01, A4 = -3.38000E-04, A6 = 2.70800E-05, A8 = -9.01000E-06
A10 = 1.04700E-06, A12 = 0.00000E + 00, A14 = 0.00000E + 00
12th page
K = 0.00000E + 00, A4 = 7.13300E-05, A6 = 1.09200E-05, A8 = -8.95000E-07
A10 = 0.00000E + 00, A12 = 0.00000E + 00, A14 = 0.00000E + 00
Side 13
K = 0.00000E + 00, A4 = 4.84000E-04, A6 = -2.97000E-05, A8 = 4.47800E-06
A10 = -3.54000E-07, A12 = 8.47300E-09, A14 = 0.00000E + 00

Table 3 (various data)

Zoom ratio 3.47604
Wide angle Medium telephoto Focal length 4.7618 8.8000 16.5521
F number 2.87953 3.78940 5.66796
Angle of view 38.1010 22.2577 12.0465
Image height 3.6000 3.6000 3.6000
Total lens length 34.0310 30.1101 33.7564
BF 0.90255 0.90007 0.96517
d4 14.5363 5.7926 1.3560
d11 2.7689 7.9799 17.7164
d13 4.5375 4.1518 2.4331
Entrance pupil position 7.7637 5.3810 3.2385
Exit pupil position -15.3369 -34.9613 197.8432
Front principal point position 11.1292 12.0216 21.1822
Rear principal point position 29.2692 21.3101 17.2043

(Numerical example 2)
The zoom lens system of Numerical Example 2 corresponds to Embodiment 2 shown in FIG. Table 4 shows surface data of the zoom lens system of Numerical Example 2, Table 5 shows aspheric data, and Table 6 shows various data.

Table 4 (surface data)

Surface number rd nd vd
Object ∞ ∞
1 33.66439 1.00000 1.90000 34.5
2 * 5.40084 1.88110
3 * 10.44550 1.60000 2.14000 17.0
4 19.13890 Variable
5 (Aperture) ∞ 0.35000
6 * 4.30187 2.10000 1.80359 40.8
7 9.00636 0.40000 1.80518 25.5
8 3.80220 0.47690
9 16.87118 1.14410 1.77250 49.6
10 -5.82973 0.40000 1.84666 23.8
11 -14.99537 Variable
12 * 34.99100 1.52000 1.66547 55.2
13 * -18.48471 Variable
14 ∞ 0.78000 1.51680 64.2
15 ∞ Variable (BF)
Image plane ∞

Table 5 (Aspheric data)

Second side
K = -1.12925E + 00, A4 = 5.48369E-04, A6 = 7.72611E-06, A8 = -2.64321E-07
A10 = -3.19936E-08, A12 = 2.34491E-09, A14 = -3.96504E-11
Third side
K = 0.00000E + 00, A4 = 1.06800E-04, A6 = 4.43655E-06, A8 = -4.86355E-07
A10 = 8.76126E-09, A12 = 4.36507E-10, A14 = -1.15222E-11
6th page
K = -1.97189E-01, A4 = -2.66278E-04, A6 = -1.92462E-05, A8 = 3.71578E-06
A10 = -3.91119E-07, A12 = 0.00000E + 00, A14 = 0.00000E + 00
12th page
K = 0.00000E + 00, A4 = -1.62384E-04, A6 = -1.51084E-05, A8 = -1.23048E-06
A10 = 0.00000E + 00, A12 = 0.00000E + 00, A14 = 0.00000E + 00
Side 13
K = 0.00000E + 00, A4 = 1.15749E-04, A6 = -2.32409E-05, A8 = -1.12886E-06
A10 = 8.83729E-09, A12 = 1.63350E-10, A14 = 0.00000E + 00

Table 6 (various data)

Zoom ratio 3.49970
Wide angle Medium telephoto Focal length 4.7500 8.7824 16.6235
F number 2.89454 3.90874 5.89289
Angle of view 38.2011 22.4995 12.0701
Image height 3.6000 3.6000 3.6000
Total lens length 34.2207 31.2999 35.2507
BF 0.89984 0.87520 0.89786
d4 14.1997 5.9266 1.3560
d11 2.7689 8.8727 18.9116
d13 4.7002 3.9733 2.4331
Entrance pupil position 7.4521 5.3533 3.3556
Exit pupil position -15.7129 -45.4197 93.5318
Front principal point position 10.8440 12.4697 22.9623
Rear principal point position 29.4707 22.5175 18.6271

(Numerical Example 3)
The zoom lens system of Numerical Example 3 corresponds to Embodiment 3 shown in FIG. Table 7 shows surface data of the zoom lens system of Numerical Example 3, Table 8 shows aspheric data, and Table 9 shows various data.

Table 7 (surface data)

Surface number rd nd vd
Object ∞ ∞
1 28.53091 1.00000 1.90000 34.5
2 * 4.88442 1.43590
3 * 8.12534 1.60000 2.14000 17.0
4 14.08892 Variable
5 (Aperture) ∞ 0.35000
6 * 4.66101 2.10000 1.88300 40.8
7 -24.62172 0.40000 1.80518 25.5
8 3.94896 0.47690
9 17.06923 0.40000 1.84700 23.8
10 15.11005 1.14410 1.62000 60.3
11 -13.33749 Variable
12 * 17.54580 1.52000 1.68863 52.8
13 * -32.20915 Variable
14 ∞ 0.78000 1.51680 64.2
15 ∞ Variable (BF)
Image plane ∞

Table 8 (Aspherical data)

Second side
K = -2.60017E + 00, A4 = 2.31962E-03, A6 = -6.70717E-05, A8 = 2.62973E-06
A10 = -8.18318E-08, A12 = 1.83415E-09, A14 = -1.36123E-11
Third side
K = 0.00000E + 00, A4 = 1.08700E-04, A6 = -1.15403E-05, A8 = 3.63218E-07
A10 = -2.68257E-09, A12 = -1.42622E-10, A14 = 6.50563E-12
6th page
K = -2.21790E-01, A4 = -2.86349E-04, A6 = -5.51190E-06, A8 = 2.07610E-06
A10 = -3.28456E-07, A12 = 0.00000E + 00, A14 = 0.00000E + 00
12th page
K = 0.00000E + 00, A4 = 7.26731E-05, A6 = -1.15440E-05, A8 = 3.00446E-07
A10 = 0.00000E + 00, A12 = 0.00000E + 00, A14 = 0.00000E + 00
Side 13
K = 0.00000E + 00, A4 = 4.25659E-04, A6 = -4.10944E-05, A8 = 2.53331E-06
A10 = -1.01328E-07, A12 = 1.92831E-09, A14 = 0.00000E + 00

Table 9 (various data)

Zoom ratio 3.49974
Wide angle Medium telephoto Focal length 4.7500 8.7828 16.6237
F number 2.89569 3.88959 5.94234
Angle of view 38.1962 22.4096 11.9775
Image height 3.6000 3.6000 3.6000
Total lens length 32.2780 29.7933 34.6736
BF 0.89449 0.87977 0.89527
d4 13.1785 5.3640 1.3560
d11 2.7747 8.4785 18.7823
d13 4.2234 3.8641 2.4331
Entrance pupil position 7.3282 5.1117 3.1683
Exit pupil position -15.3889 -47.3746 63.1204
Front principal point 10.6926 12.2959 24.2332
Rear principal point position 27.5280 21.0105 18.0498

(Numerical example 4)
The zoom lens system of Numerical Example 4 corresponds to Embodiment 4 shown in FIG. Table 10 shows surface data of the zoom lens system of Numerical Example 4, Table 11 shows aspheric data, and Table 12 shows various data.

Table 10 (surface data)

Surface number rd nd vd
Object ∞ ∞
1 42.42437 1.00000 1.90366 31.3
2 * 4.89776 1.18470
3 * 8.08910 1.60000 2.14000 17.0
4 16.88754 Variable
5 (Aperture) ∞ 0.35000
6 * 4.65929 2.10000 1.88300 40.8
7 -24.62172 0.40000 1.80518 25.5
8 3.94896 0.47690
9 19.29167 0.40000 1.84700 23.8
10 14.65353 1.14410 1.66651 57.1
11 -14.06101 Variable
12 * 18.75724 1.52000 1.68863 52.8
13 * -27.55419 Variable
14 ∞ 0.78000 1.51680 64.2
15 ∞ Variable (BF)
Image plane ∞

Table 11 (Aspheric data)

Second side
K = -2.65953E + 00, A4 = 2.30407E-03, A6 = -7.27546E-05, A8 = 2.57410E-06
A10 = -7.70188E-08, A12 = 1.82432E-09, A14 = -1.19096E-11
Third side
K = 0.00000E + 00, A4 = 1.08700E-04, A6 = -1.27248E-05, A8 = 3.93223E-07
A10 = -6.10505E-09, A12 = -7.18248E-11, A14 = 9.95377E-12
6th page
K = -2.25155E-01, A4 = -2.98075E-04, A6 = 5.33405E-06, A8 = -1.23773E-06
A10 = 2.34913E-08, A12 = 0.00000E + 00, A14 = 0.00000E + 00
12th page
K = 0.00000E + 00, A4 = 1.79016E-04, A6 = -1.52889E-05, A8 = 6.51122E-07
A10 = 0.00000E + 00, A12 = 0.00000E + 00, A14 = 0.00000E + 00
Side 13
K = 0.00000E + 00, A4 = 5.32531E-04, A6 = -4.17758E-05, A8 = 2.66353E-06
A10 = -9.39823E-08, A12 = 1.86340E-09, A14 = 0.00000E + 00

Table 12 (various data)

Zoom ratio 3.49964
Wide angle Medium telephoto Focal length 4.7500 8.7828 16.6233
F number 2.88768 3.88881 5.88165
Angle of view 38.2029 22.3849 12.0027
Image height 3.6000 3.6000 3.6000
Total lens length 32.6172 29.8325 34.1194
BF 0.89182 0.86963 0.88776
d4 13.7768 5.7107 1.3560
d11 2.7747 8.5814 18.4868
d13 4.2182 3.7151 2.4331
Entrance pupil position 7.4138 5.1212 2.9891
Exit pupil position -16.3635 -51.6751 60.3726
Front principal point position 10.7868 12.4112 24.1909
Rear principal point position 27.8672 21.0497 17.4961

(Numerical example 5)
The zoom lens system of Numerical Example 5 corresponds to Embodiment 5 shown in FIG. Table 13 shows surface data of the zoom lens system of Numerical Example 5, Table 14 shows aspheric data, and Table 15 shows various data.

Table 13 (surface data)

Surface number rd nd vd
Object ∞ ∞
1 16.96803 1.00000 2.01140 39.5
2 * 5.14390 1.98300
3 * 8.48818 1.60000 2.14000 17.0
4 12.11534 Variable
5 (Aperture) ∞ 0.35000
6 * 4.67050 2.10000 1.88300 40.8
7 -24.62172 0.40000 1.80518 25.5
8 3.94896 0.47690
9 19.35685 0.40000 1.84700 23.8
10 17.99911 1.14410 1.70182 55.1
11 -14.69344 Variable
12 * 19.72520 1.52000 1.68863 52.8
13 * -42.18457 variable
14 ∞ 0.78000 1.51680 64.2
15 ∞ Variable (BF)
Image plane ∞

Table 14 (Aspherical data)

Second side
K = -2.48292E + 00, A4 = 2.00953E-03, A6 = -3.30942E-05, A8 = 1.24549E-06
A10 = -5.41880E-08, A12 = 1.67552E-09, A14 = -1.85749E-11
Third side
K = 0.00000E + 00, A4 = 1.08700E-04, A6 = -2.79070E-06, A8 = -1.43493E-07
A10 = 7.79042E-09, A12 = -1.15456E-10, A14 = 1.05334E-12
6th page
K = -2.17125E-01, A4 = -2.75317E-04, A6 = -4.74567E-07, A8 = -6.21732E-07
A10 = 1.78573E-08, A12 = 0.00000E + 00, A14 = 0.00000E + 00
12th page
K = 0.00000E + 00, A4 = -2.15884E-04, A6 = -1.26250E-05, A8 = 1.61643E-07
A10 = 0.00000E + 00, A12 = 0.00000E + 00, A14 = 0.00000E + 00
Side 13
K = 0.00000E + 00, A4 = 1.57166E-05, A6 = -4.52204E-05, A8 = 3.51251E-06
A10 = -1.85418E-07, A12 = 4.11986E-09, A14 = 0.00000E + 00

Table 15 (various data)

Zoom ratio 3.49979
Wide angle Medium telephoto Focal length 4.7500 8.7829 16.6240
F number 2.88491 3.83528 5.80155
Angle of view 38.1871 22.5860 12.0609
Image height 3.6000 3.6000 3.6000
Total lens length 33.5257 30.3965 34.7559
BF 0.89195 0.88722 0.89251
d4 13.6977 5.5507 1.3560
d11 2.7747 8.1782 18.3203
d13 4.4073 4.0264 2.4331
Entrance pupil position 7.6379 5.4770 3.5346
Exit pupil position -14.6445 -33.5267 204.9962
Front principal point position 10.9357 12.0184 21.5126
Rear principal point position 28.7757 21.6136 18.1319

(Numerical example 6)
The zoom lens system of Numerical Example 6 corresponds to Embodiment 6 shown in FIG. Table 16 shows surface data of the zoom lens system of Numerical Example 6, Table 17 shows aspherical data, and Table 18 shows various data.

Table 16 (surface data)

Surface number rd nd vd
Object ∞ ∞
1 32.52530 1.00000 1.90000 34.5
2 * 5.00603 1.75750
3 * 9.84465 1.60000 2.14000 17.0
4 19.18101 Variable
5 (Aperture) ∞ 0.35000
6 * 4.20570 1.80000 1.80359 40.8
7 28.25180 0.40000 1.66052 31.9
8 3.50466 0.47690
9 17.16501 1.50000 1.48700 70.4
10 -4.67130 0.40000 1.89013 18.8
11 -7.01361 Variable
12 * 15.49506 1.52000 1.74993 45.4
13 * -178.29000 Variable
14 ∞ 0.78000 1.51680 64.2
15 ∞ Variable (BF)
Image plane ∞

Table 17 (Aspherical data)

Second side
K = -8.32021E-01, A4 = 3.17792E-04, A6 = -6.57172E-06, A8 = 1.25895E-06
A10 = -1.02019E-07, A12 = 3.76513E-09, A14 = -4.65581E-11
Third side
K = 0.00000E + 00, A4 = 1.06800E-04, A6 = -2.12864E-06, A8 = -3.64607E-08
A10 = 4.84060E-09, A12 = -1.01672E-10, A14 = 3.27219E-12
6th page
K = -2.09484E-01, A4 = -2.77235E-04, A6 = -1.38421E-05, A8 = 3.37592E-06
A10 = -4.05131E-07, A12 = 0.00000E + 00, A14 = 0.00000E + 00
12th page
K = 0.00000E + 00, A4 = 3.01495E-04, A6 = -1.62661E-05, A8 = 2.96182E-07
A10 = 0.00000E + 00, A12 = 0.00000E + 00, A14 = 0.00000E + 00
Side 13
K = 0.00000E + 00, A4 = 5.74280E-04, A6 = -3.08583E-05, A8 = 6.59337E-07
A10 = -4.96844E-09, A12 = 4.22418E-11, A14 = 0.00000E + 00

Table 18 (various data)

Zoom ratio 3.49972
Wide angle Medium telephoto Focal length 4.7499 8.7825 16.6233
F number 2.88633 3.89540 5.94295
Angle of view 38.1914 22.5844 12.0699
Image height 3.6000 3.6000 3.6000
Total lens length 33.4684 31.3576 36.5270
BF 0.89847 0.87890 0.87936
d4 13.4181 5.5085 1.3560
d11 2.7689 9.1885 20.2741
d13 4.7985 4.1973 2.4331
Entrance pupil position 7.0679 5.0466 3.2382
Exit pupil position -15.8279 -44.9450 90.0751
Front principal point 10.4690 12.1458 22.9595
Rear principal point position 28.7185 22.5751 19.9037

(Numerical example 7)
The zoom lens system of Numerical Example 7 corresponds to Embodiment 7 shown in FIG. Table 19 shows surface data of the zoom lens system of Numerical Example 7, Table 20 shows aspheric data, and Table 21 shows various data.

Table 19 (surface data)

Surface number rd nd vd
Object ∞ ∞
1 19.24312 1.00000 2.01140 39.5
2 * 5.30798 2.35000
3 * 10.04205 1.60000 2.14000 17.0
4 15.15011 Variable
5 (Aperture) ∞ 0.35000
6 * 4.29075 2.10000 1.80359 40.8
7 11.14632 0.40000 1.80518 25.5
8 3.80613 0.47690
9 17.37936 1.14410 1.77250 49.6
10 -6.27006 0.40000 1.84666 23.8
11 -14.15969 Variable
12 * 34.99100 1.52000 1.66547 55.2
13 * -20.70967 variable
14 ∞ 0.78000 1.51680 64.2
15 ∞ Variable (BF)
Image plane ∞

Table 20 (Aspheric data)

Second side
K = -8.17516E-01, A4 = 3.98608E-04, A6 = -9.60784E-07, A8 = 7.46777E-07
A10 = -5.70138E-08, A12 = 1.99697E-09, A14 = -2.50606E-11
Third side
K = 0.00000E + 00, A4 = 1.06800E-04, A6 = 3.36919E-08, A8 = -2.50692E-07
A10 = 2.01280E-08, A12 = -6.80328E-10, A14 = 9.19921E-12
6th page
K = -2.04713E-01, A4 = -2.84482E-04, A6 = -1.66013E-05, A8 = 3.34171E-06
A10 = -3.68981E-07, A12 = 0.00000E + 00, A14 = 0.00000E + 00
12th page
K = 0.00000E + 00, A4 = -2.60772E-04, A6 = -2.07614E-05, A8 = -1.25482E-06
A10 = 0.00000E + 00, A12 = 0.00000E + 00, A14 = 0.00000E + 00
Side 13
K = 0.00000E + 00, A4 = -4.09335E-05, A6 = -2.78087E-05, A8 = -1.25441E-06
A10 = 2.34071E-08, A12 = -1.36035E-10, A14 = 0.00000E + 00

Table 21 (various data)

Zoom ratio 3.49974
Wide angle Medium telephoto Focal length 4.7500 8.7827 16.6238
F number 2.89824 3.93676 5.98636
Angle of view 38.1925 22.5567 12.0956
Image height 3.6000 3.6000 3.6000
Total lens length 33.7266 31.6725 36.3900
BF 0.90065 0.88163 0.89653
d4 13.0728 5.4928 1.3560
d11 2.7689 9.0559 19.5834
d13 4.8633 4.1212 2.4331
Entrance pupil position 7.1764 5.3245 3.6060
Exit pupil position -15.5465 -41.7077 124.6204
Front principal point position 10.5546 12.2960 22.4635
Rear principal point position 28.9766 22.8898 19.7662

(Numerical example 8)
The zoom lens system of Numerical Example 8 corresponds to Embodiment 8 shown in FIG. Table 22 shows surface data of the zoom lens system of Numerical Example 8, Table 23 shows aspheric data, and Table 24 shows various data.

Table 22 (surface data)

Surface number rd nd vd
Object ∞ ∞
1 34.41870 1.00000 1.90000 34.5
2 * 5.19221 1.47730
3 * 8.06609 1.60000 2.14000 17.0
4 13.45253 Variable
5 (Aperture) ∞ 0.35000
6 * 4.39428 2.10000 1.80359 40.8
7 -24.62172 0.40000 1.80518 25.5
8 3.94896 0.47690
9 17.44025 0.40000 1.84666 23.8
10 15.55812 1.14410 1.77250 49.6
11 -15.55812 Variable
12 * 34.99100 1.52000 1.66547 55.2
13 * -19.99000 variable
14 ∞ 0.78000 1.51680 64.2
15 ∞ Variable (BF)
Image plane ∞

Table 23 (Aspheric data)

Second side
K = -1.49182E + 00, A4 = 1.00800E-03, A6 = -3.78000E-05, A8 = 1.55500E-06
A10 = -1.02000E-08, A12 = -8.12000E-10, A14 = 1.52000E-11
Third side
K = 0.00000E + 00, A4 = 1.08700E-04, A6 = -2.41000E-05, A8 = 1.06600E-06
A10 = -1.34000E-08, A12 = -3.75000E-10, A14 = 8.83800E-12
6th page
K = -2.12911E-01, A4 = -3.65000E-04, A6 = 2.48800E-05, A8 = -8.40000E-06
A10 = 9.51100E-07, A12 = 0.00000E + 00, A14 = 0.00000E + 00
12th page
K = 0.00000E + 00, A4 = 5.01200E-05, A6 = 9.45600E-06, A8 = -8.34000E-07
A10 = 0.00000E + 00, A12 = 0.00000E + 00, A14 = 0.00000E + 00
Side 13
K = 0.00000E + 00, A4 = 4.46900E-04, A6 = -3.48000E-05, A8 = 4.38700E-06
A10 = -3.34000E-07, A12 = 8.03600E-09, A14 = 0.00000E + 00

Table 24 (various data)

Zoom ratio 3.48789
Wide angle Medium telephoto Focal length 4.7470 8.7872 16.5570
F number 2.86224 3.73506 5.65088
Angle of View 38.2375 22.4173 12.1622
Image height 3.6000 3.6000 3.6000
Total lens length 33.9152 29.6630 33.5462
BF 0.89843 0.85513 0.87103
d4 14.5402 5.5848 1.3560
d11 2.7747 7.6153 17.6378
d13 4.4536 4.3595 2.4331
Entrance pupil position 7.7141 5.2590 3.2030
Exit pupil position -15.2920 -33.1526 192.4891
Front principal point position 11.0692 11.7757 21.1906
Rear principal point position 29.1682 20.8758 16.9892

  Table 25 below shows corresponding values for each condition in the zoom lens system of each numerical example.

Table 25 (corresponding values of conditions)

  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.

Lens arrangement diagram showing an infinitely focused state of the zoom lens system according to Embodiment 1 (Example 1) Longitudinal aberration diagram of the zoom lens system according to Example 1 in an infinitely focused state Lateral aberration diagram in the basic state where image blur correction is not performed and in the image blur correction state at the telephoto end of the zoom lens system according to Embodiment 1 Lens arrangement diagram showing an infinitely focused state of the zoom lens system according to Embodiment 2 (Example 2) Longitudinal aberration diagram of the zoom lens system according to Example 2 in an infinitely focused state Lateral aberration diagrams in the basic state where image blur correction is not performed and in the image blur correction state at the telephoto end of the zoom lens system according to Example 2 Lens arrangement diagram showing an infinitely focused state of the zoom lens system according to Embodiment 3 (Example 3) Longitudinal aberration diagram of the zoom lens system according to Example 3 in an infinitely focused state Lateral aberration diagram in the basic state where image blur correction is not performed and in the image blur correction state at the telephoto end of the zoom lens system according to Example 3 Lens arrangement diagram showing an infinitely focused state of the zoom lens system according to Embodiment 4 (Example 4) Longitudinal aberration diagram of the zoom lens system according to Example 4 in an infinitely focused state Lateral aberration diagrams in the basic state where image blur correction is not performed and in the image blur correction state at the telephoto end of the zoom lens system according to Example 4 Lens arrangement diagram showing an infinitely focused state of a zoom lens system according to Embodiment 5 (Example 5) Longitudinal aberration diagram of the zoom lens system according to Example 5 in an infinitely focused state Lateral aberration diagrams in the basic state where image blur correction is not performed and in the image blur correction state at the telephoto end of the zoom lens system according to Example 5 Lens arrangement diagram showing an infinitely focused state of a zoom lens system according to Embodiment 6 (Example 6) Longitudinal aberration diagram of the zoom lens system according to Example 6 in focus at infinity Lateral aberration diagrams in the basic state where image blur correction is not performed and in the image blur correction state at the telephoto end of the zoom lens system according to Example 6 Lens arrangement diagram showing an infinitely focused state of a zoom lens system according to Embodiment 7 (Example 7) Longitudinal aberration diagram of the zoom lens system according to Example 7 in a focused state at infinity Lateral aberration diagrams in the basic state where image blur correction is not performed and in the image blur correction state at the telephoto end of the zoom lens system according to Example 7 Lens arrangement diagram showing an infinitely focused state of the zoom lens system according to Embodiment 8 (Example 8) Longitudinal aberration diagram of the zoom lens system according to Example 8 at the infinite focus state Lateral aberration diagrams in the basic state where image blur correction is not performed and in the image blur correction state at the telephoto end of the zoom lens system according to Example 8 Schematic configuration diagram of a digital still camera according to Embodiment 9

Explanation of symbols

G1 1st lens group G2 2nd lens group G3 3rd lens group L1 1st lens element L2 2nd lens element L3 3rd lens element L4 4th lens element L5 5th lens element L6 6th lens element L7 7th lens element L8 Parallel plate A Aperture S Image plane 1 Zoom lens system 2 Image sensor 3 Liquid crystal monitor 4 Case 5 Main barrel 6 Moving barrel 7 Cylindrical cam

Claims (16)

In order from the object side to the image side consists of a first lens unit having negative optical power, a second lens group having a positive power, a third lens unit having positive optical power,
In order from the object side to the image side, the first lens group includes a first lens element having a concave surface at least on the image side and having negative power, and a second lens element having a convex surface at least on the object side and having positive power. And two lens elements,
The second lens group, in order from the object side to the image side, a first cemented lens element formed by cementing a third lens element and a fourth lens element having different powers, respectively, and a different code A second cemented lens element formed by cementing a fifth lens element and a sixth lens element having the following power:
During zooming from the wide-angle end to the telephoto end, the first lens group, the second lens group, and the third lens group all move along the optical axis,
A zoom lens system that satisfies the following conditions (1) and (2):
5.0 <αi _W <20.0 (1)
(N ₁₁ −1) · (n ₁₂ −1) ≧ 0.84 (2)
(However, 3.2 <f _T / f _W , ω _W > 35)
here,
αi _W : imaging element incident angle of the principal ray at the maximum image height at the wide-angle end (when the principal ray is incident on the light receiving surface of the imaging element while being separated from the optical axis)
n ₁₁ : refractive index with respect to d-line of the first lens element,
n ₁₂ : refractive index with respect to d-line of the second lens element,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end. The zoom lens system according to claim 1, satisfying the following condition (5):
_{0.1 <(n 11 -1) ·} (n 12 -1) · d · f W / (r 12 · r 21) <0.3
... (5)
(However, 3.2 <f _T / f _W , ω _W > 35)
here,
n ₁₁ : refractive index with respect to d-line of the first lens element,
n ₁₂ : refractive index with respect to d-line of the second lens element,
r ₁₂ : radius of curvature of the image side surface of the first lens element,
r ₂₁ : radius of curvature of the object side surface of the second lens element,
d: optical axis upper surface distance between the image side surface of the first lens element and the object side surface of the second lens element;
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end. The zoom lens system according to claim 1, satisfying the following condition (6):
0.0001 <(n ₁₁ −1) · (n ₁₂ −1) · d ² · f _T / (r ₁₂ · r ₂₁ · f _W )
<0.04 (6)
(However, 3.2 <f _T / f _W , ω _W > 35)
here,
n ₁₁ : refractive index with respect to d-line of the first lens element,
n ₁₂ : refractive index with respect to d-line of the second lens element,
r ₁₂ : radius of curvature of the image side surface of the first lens element,
r ₂₁ : radius of curvature of the object side surface of the second lens element,
d: optical axis upper surface distance between the image side surface of the first lens element and the object side surface of the second lens element;
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end. The zoom lens system according to claim 1, satisfying the following condition (7):
1.0 <(r ₁₂ + r ₂₁ ) / (r ₁₂ −r ₂₁ ) <2.5 (7)
(However, 3.2 <f _T / f _W , ω _W > 35)
here,
r ₁₂ : radius of curvature of the image side surface of the first lens element,
r ₂₁ : radius of curvature of the object side surface of the second lens element,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end. The zoom lens system according to claim 1, satisfying the following condition (8):
0.5 <| f _AIR | / f _W <1.1 (8)
(However, 3.2 <f _T / f _W , ω _W > 35)
here,
f _AIR : Focal length of the air lens formed between the image side surface of the first lens element and the object side surface of the second lens element,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end. The zoom lens system according to claim 1, satisfying the following condition (9):
2.4 <| f _G1 | / f _W <4.0 (9)
(However, 3.2 <f _T / f _W , ω _W > 35)
here,
f _G1 : composite focal length of the first lens group,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end. The zoom lens system according to claim 1, wherein the zoom lens system satisfies the following condition (10):
1.85 <f _G2 / f _W <3.0 (10)
(However, 3.2 <f _T / f _W , ω _W > 35)
here,
f _G2 : Composite focal length of the second lens group,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end. The zoom lens system according to claim 1, satisfying the following condition (11):
2.5 <f _G3 / f _W <6.0 (11)
(However, 3.2 <f _T / f _W , ω _W > 35)
here,
f _G3 : composite focal length of the third lens group,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end. The zoom lens system according to claim 1, satisfying the following condition (12):
1.0 <| f _L1 | / f _W <2.5 (12)
(However, 3.2 <f _T / f _W , ω _W > 35)
here,
f _L1 : focal length of the first lens element,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end. The zoom lens system according to claim 1, satisfying the following condition (13):
2.0 <f _L2 / f _W <5.0 (13)
(However, 3.2 <f _T / f _W , ω _W > 35)
here,
f _L2 : focal length of the second lens element,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end. The zoom lens system according to claim 1, satisfying the following condition (14):
0.4 <| f _L1 | / | f _G1 | <0.8 (14)
(However, 3.2 <f _T / f _W , ω _W > 35)
here,
f _L1 : focal length of the first lens element,
f _G1 : composite focal length of the first lens group,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end. The zoom lens system according to claim 1, satisfying the following condition (15):
0.85 <f _L2 / | f _G1 | <2.0 (15)
(However, 3.2 <f _T / f _W , ω _W > 35)
here,
f _L2 : focal length of the second lens element,
f _G1 : composite focal length of the first lens group,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end. The zoom lens system according to claim 1, wherein the zoom lens system satisfies the following condition (16):
1.9 <f _L2 / | f _L1 | <3.0 (16)
(However, 3.2 <f _T / f _W , ω _W > 35)
here,
f _L1 : focal length of the first lens element,
f _L2 : focal length of the second lens element,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W : the focal length of the entire system at the wide angle end.   The zoom lens system according to claim 1, wherein the second lens group moves in a direction perpendicular to the optical axis. An imaging apparatus capable of outputting an optical image of an object as an electrical image signal,
A zoom lens system that forms an optical image of the object;
An image sensor that converts an optical image formed by the zoom lens system into an electrical image signal;
The zoom lens system is
In order from the object side to the image side consists of a first lens unit having negative optical power, a second lens group having a positive power, a third lens unit having positive optical power,
In order from the object side to the image side, the first lens group includes a first lens element having a concave surface at least on the image side and having negative power, and a second lens element having a convex surface at least on the object side and having positive power. And two lens elements,
The second lens group, in order from the object side to the image side, a first cemented lens element formed by cementing a third lens element and a fourth lens element having different powers, respectively, and a different code A second cemented lens element formed by cementing a fifth lens element and a sixth lens element having the following power:
During zooming from the wide-angle end to the telephoto end, the first lens group, the second lens group, and the third lens group all move along the optical axis,
The following conditions (1) and (2):
5.0 <αi _W <20.0 (1)
(N ₁₁ −1) · (n ₁₂ −1) ≧ 0.84 (2)
(However, 3.2 <f _T / f _W , ω _W > 35)
(here,
αi _W : imaging element incident angle of the principal ray at the maximum image height at the wide-angle end (when the principal ray is incident on the light receiving surface of the imaging element while being separated from the optical axis)
n ₁₁ : refractive index with respect to d-line of the first lens element,
n ₁₂ : refractive index with respect to d-line of the second lens element,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W is the focal length of the entire system at the wide-angle end)
Satisfying the imaging device. A camera that converts an optical image of an object into an electrical image signal, and displays and stores the converted image signal;
An image pickup apparatus including a zoom lens system that forms an optical image of an object, and an image sensor that converts an optical image formed by the zoom lens system into an electrical image signal;
The zoom lens system is
In order from the object side to the image side consists of a first lens unit having negative optical power, a second lens group having a positive power, a third lens unit having positive optical power,
In order from the object side to the image side, the first lens group includes a first lens element having a concave surface at least on the image side and having negative power, and a second lens element having a convex surface at least on the object side and having positive power. And two lens elements,
The second lens group, in order from the object side to the image side, a first cemented lens element formed by cementing a third lens element and a fourth lens element having different powers, respectively, and a different code A second cemented lens element formed by cementing a fifth lens element and a sixth lens element having the following power:
During zooming from the wide-angle end to the telephoto end, the first lens group, the second lens group, and the third lens group all move along the optical axis,
The following conditions (1) and (2):
5.0 <αi _W <20.0 (1)
(N ₁₁ −1) · (n ₁₂ −1) ≧ 0.84 (2)
(However, 3.2 <f _T / f _W , ω _W > 35)
(here,
αi _W : imaging element incident angle of the principal ray at the maximum image height at the wide-angle end (when the principal ray is incident on the light receiving surface of the imaging element while being separated from the optical axis)
n ₁₁ : refractive index with respect to d-line of the first lens element,
n ₁₂ : refractive index with respect to d-line of the second lens element,
ω _W : Half field angle (°) at the wide-angle end,
f _T : focal length of the entire system at the telephoto end,
f _W is the focal length of the entire system at the wide-angle end)
Satisfy the camera.

Images