JP5769606B2 - Zoom lens and image pickup apparatus including the same - Google Patents

Description

  The present invention relates to a zoom lens, and relates to a zoom lens having a high zoom ratio including a medium telephoto range or a telephoto range. Furthermore, the present invention relates to an imaging apparatus provided with the zoom lens.

  Conventionally, a zoom lens used for an interchangeable lens for a single-lens reflex camera or the like has been required to have a high zoom ratio. As a configuration capable of increasing the zoom ratio, a five-group configuration including positive, negative, positive and negative lens groups from the object side is known (see Patent Document 1).

In recent years, with the improvement of the performance of digital cameras, the continuous shooting function and the moving image function have been enhanced, and in order to cope with these functions, the image blur correction and focusing of the lens optical system are required to be immediate. In order to improve the immediacy at the time of focusing, it is required to make the focusing lens group as small as possible and to reduce the movement amount of the driving group at the time of focusing. As a zoom lens having a small change in image magnification when the focusing lens group is moved, a zoom lens as shown in Patent Document 2 has been proposed. In the zoom lens disclosed in Patent Document 2, a positive fourth lens group having a small lens diameter and the number of lenses among the five groups of positive, negative, negative, and positive zoom lenses as viewed from the object side is used as a moving group at the time of focusing. The power burden due to group movement during focus correction is suppressed.

JP 2010-191199 A JP 2009-265652 A

  In order to achieve a high zoom ratio, it is necessary to increase the number of components of each lens in order to correct aberrations while increasing the burden of magnification on each lens unit. It has been difficult to reduce the amount of movement, to reduce the amount of movement of the lens group, and to improve the immediacy of focusing. Further, when the configuration of the focusing lens group is reduced and the immediacy of focusing is increased, it is difficult to achieve a high zoom ratio, and it is difficult to satisfy both requirements at the same time.

  The present invention has been made in view of the above-mentioned problems, and reduces the power burden during focusing by making the configuration of the focusing lens group as small as possible and having a small number of lens groups while having a high zoom ratio. In addition, a zoom lens is provided in which the amount of movement at the time of focusing is reduced to improve the immediacy of focusing. In addition, an imaging apparatus including such a zoom lens is provided.

The first embodiment of the zoom lens of the present invention is
From the object side to the image side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having negative refractive power;
A fifth lens group having positive refractive power;
Consists of
The first lens group includes:
Consists of three or more lenses,
The third lens group in order from the object side to the image side,
It consists of a 3a lens group and a 3b lens group,
The 3a lens group includes a positive lens and a negative lens,
The third lens group includes a positive lens and a negative lens,
The fourth lens group includes:
Consists of two or less lenses,
Moving the first lens group at the time of zooming from the wide-angle end to the telephoto end;
Move the fourth lens group during focusing,
The following conditional expression (1) and conditional expression (2A) are satisfied.
−0.8 <f _Four   / F _W   <-0.3 (1)
0.15 <d _G3   / L _W   <0.4 (2A)
However,
f _W Is the focal length of the entire zoom lens system at the wide-angle end,
f _Four Is the focal length of the fourth lens group,
d _G3 Is the thickness of the third lens group on the optical axis,
L _W Is the total length of the entire zoom lens system at the wide-angle end,
It is.

  The reason and effect | action which take such a structure are demonstrated.

  In order to increase the zoom ratio, the zoom lens has a positive, negative, positive and negative configuration in order from the object side to the image side. In addition, the number of lenses of the fourth lens group is configured to be two or less, and the fourth lens group is a focusing lens group, thereby reducing the driving force for moving the focusing lens group.

  Further, the third lens group is composed of a 3a lens group on the object side and a 3b lens group on the image side, and constitutes two partial groups before and after the maximum air gap in the third lens group. ing.

  Among these, the 3a lens group plays a role of focusing and transmitting the light beam to the subsequent group in the telephoto state.

  Conditional expression (1) is a conditional expression regarding the refractive power of the fourth lens group, and is a conditional expression for balancing the aberration performance and the driving amount of the fourth lens group.

  If the upper limit of conditional expression (1) is exceeded, the refractive power of the fourth lens group becomes too strong, and it becomes impossible to balance aberration in each state including spherical aberration at the telephoto end. In order to correct the aberration performance, it is necessary to increase the number of constituent elements of the fourth lens group, and the driving load of the fourth lens group increases.

  If the lower limit of conditional expression (1) is not reached, the refractive power of the fourth lens group becomes weak, so the driving amount of the fourth lens group at the time of focusing becomes large, and the immediacy of focusing is hindered. Furthermore, the total lens length becomes long, and it becomes difficult to achieve a compact configuration.

  Conditional expression (2) is an expression that prescribes the overall length of the third lens group, and is normalized by the overall length of the entire zoom lens system at the wide angle end.

  If the lower limit of the conditional expression (2) is not reached, the distance between the 3a lens group and the 3b lens group becomes too short, and the above-described 3a lens group is in a telephoto state, and the effect of focusing the light beam on the subsequent group becomes small. For this reason, the aperture diameter of the fourth lens group into which the light beam enters next increases, and the driving burden during focusing increases, thereby impeding the immediacy of focusing. In addition, since the lens diameter is increased, it is difficult to achieve a compact configuration.

  If the upper limit of conditional expression (2) is exceeded, the total length of the third lens group becomes too long, and the total lens length is increased.

The second embodiment of the zoom lens of the present invention is
From the object side to the image side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having negative refractive power;
A fifth lens group having positive refractive power;
Consists of
The first lens group includes:
Consists of three or more lenses,
The third lens group in order from the object side to the image side,
It consists of a 3a lens group and a 3b lens group,
The 3a lens group includes a positive lens and a negative lens,
The third lens group includes a positive lens and a negative lens,
The fourth lens group is composed of two or less lenses,
Moving the first lens group at the time of zooming from the wide-angle end to the telephoto end;
Move the fourth lens group during focusing,
The following conditional expression (1), conditional expression (3), and conditional expression (8) are satisfied.
_{-0.8 <f 4 / f W <} -0.3 ··· (1)
_{2 <f 1 / f W <} 4 ··· (3)
1.9 < _dG3 / _dG2 <5 (8)
However,
f _W is the focal length of the entire zoom lens system at the wide-angle end,
f ₄ is the focal length of the fourth lens group,
f ₁ is the focal length of the first lens group,
d _G2 is the thickness of the second lens group on the optical axis,
d _G3 is the thickness of the third lens group on the optical axis,
It is.

  The reason and action of taking the above configuration and conditional expression (1) are as already described.

  Conditional expression (3) is a conditional expression regarding the refractive power of the first lens unit.

  If the upper limit of conditional expression (3) is exceeded, the refractive power of the first lens group becomes too small, and the amount of movement of the first lens group during zooming increases, so the total length of the entire zoom system at the telephoto end increases. It becomes difficult to take a compact configuration. Also, in order to maintain a high zoom ratio, it is necessary to increase the burden of zooming on other positive groups, and it becomes difficult to correct image plane fluctuations that occur by increasing the refractive power of other positive groups. .

  If the lower limit of conditional expression (3) is not reached, the refractive power of the first lens group becomes too large, so that the occurrence of lateral chromatic aberration becomes large at the wide-angle end where the incident height is high, making it difficult to correct aberrations.

Furthermore, the third embodiment of the zoom lens according to the present invention includes:
From the object side to the image side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having negative refractive power;
A fifth lens group having positive refractive power;
Consists of
The first lens group includes:
Consists of three or more lenses,
The third lens group in order from the object side to the image side,
It consists of a 3a lens group and a 3b lens group,
The 3a lens group includes a positive lens and a negative lens,
The third lens group includes a positive lens and a negative lens,
The fourth lens group includes:
Consists of two or less lenses,
When zooming from the wide-angle end to the telephoto end,
Moving the first lens group;
Moving the third lens group to the object side monotonously;
Move the fourth lens group during focusing,
The following conditional expressions (1) and (8) are satisfied.
_{-0.8 <f 4 / f W <} -0.3 ··· (1)
1.9 < _dG3 / _dG2 <5 (8)
However,
f _W is the focal length of the entire zoom lens system at the wide-angle end,
f ₄ is the focal length of the fourth lens group,
d _G2 is the thickness of the second lens group on the optical axis,
d _G3 is the thickness of the third lens group on the optical axis,
It is.

  It is preferable that the third lens group is a group having a large number of lenses and mainly responsible for zooming. When zooming from the wide-angle end to the telephoto end, the third lens unit is moved monotonically toward the object side, so that it is possible to increase the zooming ratio while correcting aberrations without difficulty.

  In the zoom lens according to the first to third embodiments of the present invention, it is preferable that the fourth lens group includes at least one refractive optical element that satisfies the following conditional expression (4).

1.4 <nd (LD) <1.6 (4)
Where nd (LD) is the refractive index of the refractive optical element.

  Conditional expression (4) defines the refractive index of at least one refractive index optical element present in the fourth lens group.

  Exceeding the upper limit of conditional expression (4) is not preferable because the glass has a large specific gravity and the weight of the focus group increases, impeding the immediacy of focusing.

  If the lower limit of conditional expression (4) is not reached, it is not preferable because various aberrations such as field curvature that occurs during focusing cannot be sufficiently corrected.

  In the zoom lenses according to the first to third embodiments of the present invention, it is preferable that the following conditional expression (5) is satisfied.

1 <ρ ₄ <3.7 (5)
Here, ρ ₄ is the specific gravity of the lens in the fourth lens group.

  Exceeding the upper limit of conditional expression (5) is not preferable because the glass has a large specific gravity and the weight of the focus group increases, which impedes the immediacy of focusing.

  If the lower limit of conditional expression (5) is not reached, it is not preferable because various aberrations such as field curvature that occurs during focusing cannot be sufficiently corrected.

  In the zoom lenses according to the first to third embodiments of the present invention, it is preferable that the following conditional expression (6) is satisfied.

_{0.5 <f 3 / f W <} 0.9 ··· (6)
Here, f ₃ is the focal length of the third lens group.

  Conditional expression (6) is a conditional expression regarding the refractive power of the third lens unit.

  If the upper limit of conditional expression (6) is exceeded, the refractive power of the third lens group becomes too small, and in order to maintain a high zoom ratio, it is necessary to increase the amount of movement of the third lens group. The overall length of the entire zoom lens system is undesirably long.

  On the other hand, if the lower limit of conditional expression (6) is not reached, the refractive power of the third lens group becomes too large, and it is not preferable because the spherical aberration and axial chromatic aberration balance in the vicinity of the telephoto end cannot be achieved.

  In the zoom lenses according to the first to third embodiments of the present invention, it is preferable that the second lens group includes a lens having a refractive index of 1.85 or more.

  When a lens having a refractive index of 1.85 or more is not included, the Petzval sum becomes negatively large, and the SM separation of the image surface becomes large, which is not preferable.

  In the zoom lenses according to the first to third embodiments of the present invention, it is preferable that at least one lens surface of the fourth lens group is an aspherical surface.

  This is because, when the fourth lens group is driven as a focusing lens group, aberration variation accompanying focusing on a short distance is further reduced.

  In the zoom lenses according to the first to third embodiments of the present invention, it is preferable that the following conditional expression (7) is satisfied.

_{0.2 <d G2 / f W <} 0.5 ··· (7)
Here, d _G2 is the thickness on the optical axis of the second lens group.

  Conditional expression (7) is a conditional expression regarding the thickness of the second lens group on the optical axis.

  If the upper limit of conditional expression (7) is exceeded, the second lens group becomes too large, and the overall length of the entire zoom lens system becomes undesirably large.

  If the lower limit of conditional expression (7) is not reached, the thickness of the second lens group on the optical axis is too thin, so that the radius of curvature of the negative lens in the second lens group cannot be reduced, and the second lens group. Aberration correction function does not work sufficiently. For this reason, the refractive power of the second lens group inevitably has to be weakened, and correction of lateral chromatic aberration and field curvature becomes insufficient.

  In the zoom lenses according to the first to third embodiments of the present invention, it is preferable that the fourth lens group includes a resin lens.

  By including a resin lens in the fourth lens group, the weight of the fourth lens group can be reduced. Therefore, it is possible to reduce a burden when driving as a focusing lens group, which is advantageous in immediacy at the time of focusing.

  In the zoom lenses according to the first to third embodiments of the present invention, it is preferable that the fourth lens group is composed of a single lens.

  By making the number of constituent elements of the fourth lens group one, the weight of the fourth lens group can be reduced. Therefore, it is possible to reduce a burden when driving as a focusing lens group, which is advantageous in immediacy at the time of focusing.

  In the zoom lenses according to the first to third embodiments of the present invention, the third lens group has an aperture stop, and when zooming from the wide-angle end to the telephoto end, the aperture stop is It is preferable to move integrally with the third lens group.

  In general, the optical system has the smallest luminous flux system near the stop. For this reason, the lens in the vicinity of the stop can be easily reduced in diameter as compared with other lenses arranged at positions away from the vicinity of the stop in the optical axis direction. Therefore, for example, when the stop is arranged in the most image side group, the diameter of the most object side group becomes too large, and when the stop is arranged in the most object side group, the diameter of the most image side group becomes too large. End up. In the zoom lenses according to the first embodiment to the third embodiment of the present invention, the lens diameter of the first lens group on the object side is increased by arranging an aperture stop in the third lens group near the center of the optical system. And the size of the lens diameter of the fourth lens group on the image side can be antagonized, and the maximum diameter of the entire optical system can be reduced.

  In the zoom lenses according to the first to third embodiments of the present invention, it is preferable that the following conditional expression (8) is satisfied.

1.9 < _dG3 / _dG2 <5 (8)
Conditional expression (8) defines the ratio between the thickness of the third lens group on the optical axis and the thickness of the second lens group on the optical axis.

  If the lower limit of conditional expression (8) is not reached, the distance between the 3a lens group and the 3b lens group becomes too short, and the above-described 3a lens group is in the telephoto state, and the action of focusing the light beam on the subsequent group becomes small. For this reason, the aperture of the fourth lens group into which the light beam enters next increases, and the driving load during focusing increases, thereby impeding the immediacy of focusing. Further, since the lens diameter is increased, it is difficult to adopt a compact configuration.

  If the upper limit of conditional expression (8) is exceeded, the third lens group will be too long, and the total lens length will be long.

  In the zoom lenses according to the first to third embodiments of the present invention, it is preferable that the following conditional expression (9) is satisfied.

_{-0.25 <f 4 / f t <} -0.05 ··· (9)
Here, _ft is the focal length of the entire zoom lens system at the telephoto end.

  Conditional expression (9) is a conditional expression regarding the refractive power of the fourth lens group, and is a conditional expression for balancing the aberration performance and the driving amount of the fourth lens group.

  If the upper limit of conditional expression (9) is exceeded, the refractive power of the fourth lens group becomes too strong, and the aberration balance in each state including spherical aberration at the telephoto end cannot be achieved. Further, when correcting the aberration performance, it is necessary to increase the number of constituent elements of the fourth lens group, and the driving load of the fourth lens group increases.

  If the lower limit of conditional expression (9) is not reached, the refractive power of the fourth lens group becomes weak, so the driving amount of the fourth lens group at the time of focusing becomes large, and the immediacy of focusing is hindered. In addition, the overall length of the lens becomes long, making it difficult to adopt a compact configuration.

  Moreover, it becomes a more preferable structure by changing a conditional expression as follows.

−0.75 <f ₄ / f _W <−0.4 (1) ′
0.15 < _dG3 / _LW <0.3 (2) '
_{2.2 <f 1 / f W <} 3.8 ··· (3) '
1.45 <nd (LD) <1.57 (4) ′
0.6 <f ₃ / f _W <0.85 (5) ′
_{0.25 <d G2 / f W <} 0.4 ··· (6) '
2.1 < _dG3 / _dG2 <4 (7) '
_{-0.2 <f 4 / f t <} -0.08 ··· (8) '
Furthermore, it becomes a more preferable structure by changing the conditional expression as follows.

_{-0.72 <f 4 / f W <} -0.5 ··· (1) ''
_{0.19 <d G3 / L W <} 0.27 ··· (2) ''
_{2.5 <f 1 / f W <} 3.5 ··· (3) ''
1.5 <nd (LD) <1.57 (4) ''
0.7 <f ₃ / f _W <0.85 (5) ''
_{0.27 <d G2 / f W <} 0.35 ··· (6) ''
2.4 < _dG3 / _dG2 <3.5 (7) ''
_{-0.15 <f 4 / f t <} -0.1 ··· (8) ''

  According to the present invention, it is possible to provide a zoom lens that has a high zoom ratio and an improved focus immediacy. Furthermore, it is possible to provide an imaging apparatus provided with such a zoom lens.

FIG. 3 is a cross-sectional view taken along the optical axis of the zoom lens according to the first exemplary embodiment. FIG. 6 is a cross-sectional view taken along the optical axis by developing the zoom lens of Example 2. FIG. 6 is a cross-sectional view taken along the optical axis by developing the zoom lens of Example 3. FIG. 9 is a cross-sectional view taken along the optical axis by developing the zoom lens of Example 4. FIG. 10 is a cross-sectional view taken along the optical axis by developing the zoom lens of Example 5. FIG. 9 is a cross-sectional view taken along the optical axis by developing the zoom lens of Example 6. FIG. 6 is an aberration diagram of the zoom lens according to Example 1; FIG. 6 is an aberration diagram of the zoom lens according to Example 2; FIG. 6 is an aberration diagram of the zoom lens according to Example 3; FIG. 6 is an aberration diagram of the zoom lens according to Example 4; FIG. 10 is an aberration diagram of the zoom lens according to Example 5; FIG. 10 is an aberration diagram of the zoom lens according to Example 6; It is sectional drawing of the imaging device which used the zoom lens of one Embodiment as an interchangeable lens. It is a front perspective view which shows the external appearance of the digital camera of one Embodiment. It is a back perspective view showing the appearance of the digital camera of one embodiment. It is a front perspective view which shows the external appearance of the digital camera of other embodiment. It is a rear view which shows the external appearance of the digital camera of other embodiment. It is a typical cross-sectional view which shows the structure of the digital camera of other embodiment. It is a block diagram which shows the control structure of the digital camera of this embodiment.

  Embodiments 1 to 6 of the present invention will be described with reference to the drawings. 1 to 6 are sectional views taken along the optical axis of the zoom lenses according to the first to sixth embodiments of the present invention. In each figure, (a) shows the wide-angle end (WE), (b) shows the intermediate state (ST), and (c) shows the telephoto end (TE).

  The flat plate immediately before the imaging surface is a cover glass C of the imaging device.

  FIG. 1 is a cross-sectional view of the zoom lens according to the first exemplary embodiment.

As shown in FIG. 1, the zoom lens according to the first exemplary embodiment includes, in order from the object side to the image side, a first lens group G _{1 having} a positive refractive power, a second lens group G _{2 having} a negative refractive power, and a third lens having a positive refractive power. The lens unit includes a lens group G ₃ , a fourth lens group G _{4 having} a negative refractive power, and a fifth lens group G _{5 having} a positive refractive power. In the figure, S is the aperture stop, C is the cover glass, and I is the image plane.

The first lens group G ₁ includes, in order from the object side to the image side, a biconvex lens L ₁₁ , a negative meniscus lens L ₁₂ having a convex surface facing the object side, and a positive meniscus lens L ₁₃ having a convex surface facing the object side. and SU _11, consisting of.

The second lens group G ₂ includes, in order from the object side to the image side, a positive meniscus lens L ₂₁ having a convex surface facing the image side, a biconcave negative lens L _22, and a positive meniscus lens L ₂₃ having a convex surface facing the object side. It consists of a lens SU ₂₁ and a biconcave negative lens L ₂₄ .

The third lens group G ₃ includes a 3a lens group G _3a and a 3b lens group G _{3b in} order from the object side to the image side. The third-a lens group G _3a includes, in order from the object side to the image side, a biconvex positive lens L _3a1, and a cemented lens SU ₃₁ of the biconvex positive lens L _3a2 and the biconcave negative lens L _3a3 . Further, the 3b-th lens group G _3b, in order from the object side to the image side, a biconvex positive lens L _3b1, a biconvex positive lens L _3b2, a biconcave negative lens L _3b3, positive having a convex surface directed toward the object side Meniscus lens L _3b4 .

The 3a lens group G _3a of the third lens group G ₃ and between the 3b lens group G _3b, is disposed aperture stop S.

The fourth lens group G ₄ includes a biconvex positive lens L ₄₁ and a biconcave negative lens L ₄₂ .

G ₅ is the fifth lens group consists of one double-convex positive lens L _51.

  Next, the movement of each lens group when zooming from the wide-angle end to the telephoto end of the zoom lens of Example 1 will be described.

In the zoom operation, the first lens group G ₁ , the second lens group G ₂ , the third lens group G ₃ , the fourth lens group G ₄ , and the fifth lens group G ₅ move independently of each other.

The first lens group G ₁ moves from the wide-angle end to the telephoto end only at the object side by increasing the distance from the second lens group G ₂ . The first lens group G ₁ is located closer to the object side at the telephoto end than at the wide-angle end.

The second lens group G ₂ moves from the wide-angle end to the intermediate state toward the image side while increasing the distance from the first lens group G ₁ and narrowing the distance from the third lens group G _3, and from the intermediate state to the telephoto end. Until the first lens group G ₁ is widened and the distance from the third lens group G ₃ is narrowed. The second lens group G ₂ is located closer to the image side than the wide-angle end at the telephoto end.

The third lens group G ₃ moves along with the aperture stop S to the object side from the wide-angle end to the intermediate state by narrowing the distance from the second lens group G ₂ and widening the distance from the fourth lens group G _4. , from the intermediate state to the telephoto end, narrowing the distance between the second lens group G _2, it moves to the object side while narrowing the distance between the fourth lens group G _4. The third lens group G ₃ is located closer to the object side at the telephoto end than at the wide-angle end.

The fourth lens group G ₄ moves from the wide-angle end to the intermediate state and moves toward the object side while widening the distance from the third lens group G ₃ and widening the distance from the fifth lens group G _5, and from the intermediate state to the telephoto end. Until the distance from the third lens group G ₃ is narrowed, the distance from the fifth lens group G ₅ is increased, and the lens moves toward the object side. The telephoto end is located closer to the object side than the wide-angle end.

The fifth lens group G ₅ increases the distance from the fourth lens group G ₄ from the wide-angle end to the telephoto end, and moves only to the image side. The fifth lens group G ₅ is positioned closer to the image side than the wide angle end at the telephoto end.

The aspheric surfaces are the two surfaces r ₂₈ and r ₂₉ of the biconcave negative lens L ₄₂ of the fourth lens group G ₄ .

  FIG. 2 is a cross-sectional view of the zoom lens according to the second embodiment.

As shown in FIG. 2, the zoom lens according to the second embodiment includes, in order from the object side to the image side, a first lens group G _{1 having} a positive refractive power, a second lens group G _{2 having} a negative refractive power, and a first lens group having a positive refractive power. The third lens group G ₃ includes a fourth lens group G _{4 having} a negative refractive power and a fifth lens group G _{5 having} a positive refractive power. In the figure, S is the aperture stop, C is the cover glass, and I is the image plane.

The first lens group G ₁ has, in order from the object side to the image side, a positive meniscus lens L ₁₁ having a convex surface facing the object side, a negative meniscus lens L ₁₂ having a convex surface facing the object side, and a convex surface facing the object side. a cemented lens SU ₁₁ of the positive meniscus lens L _13, made of.

The second lens group G ₂ includes, in order from the object side to the image side, a biconvex positive lens L ₂₁ , a biconcave negative lens L ₂₂ , a cemented lens SU _{21 of} a positive meniscus lens L ₂₃ having a convex surface facing the object side, a negative lens L _24, made of.

The third lens group G ₃ includes a 3a lens group G _3a and a 3b lens group G _{3b in} order from the object side to the image side. The third-a lens group G _3a includes, in order from the object side to the image side, a biconvex positive lens L _3a1, and a cemented lens SU ₃₁ of the biconvex positive lens L _3a2 and the biconcave negative lens L _3a3 . Further, the 3b-th lens group G _3b, in order from the object side to the image side, a biconvex positive lens L _3b1, a biconvex positive lens L _3b2, a biconcave negative lens L _3b3, positive having a convex surface directed toward the object side Meniscus lens L _3b4 .

The 3a lens group G _3a of the third lens group G ₃ and between the 3b lens group G _3b, is disposed aperture stop S.

The fourth lens group G4, in order from the object side to the image side, a positive meniscus lens L ₄₁ having a convex surface directed toward the image side, a biconcave negative lens L _42, made of.

G ₅ is the fifth lens group consists of one double-convex positive lens L _51.

  Next, the movement of each lens group when zooming from the wide-angle end to the telephoto end of the zoom lens of Example 2 will be described.

In the zoom operation, the first lens group G ₁ , the second lens group G ₂ , the third lens group G ₃ , the fourth lens group G ₄ , and the fifth lens group G ₅ move independently of each other.

The first lens group G ₁ moves from the wide-angle end to the telephoto end only at the object side by increasing the distance from the second lens group G ₂ . The first lens group G ₁ is located closer to the object side at the telephoto end than at the wide-angle end.

The second lens group G ₂ moves from the wide-angle end to the intermediate state toward the image side while increasing the distance from the first lens group G ₁ and narrowing the distance from the third lens group G _3, and from the intermediate state to the telephoto end. Until the first lens group G ₁ is widened and the distance from the third lens group G ₃ is narrowed. The second lens group G ₂ is located closer to the image side than the wide-angle end at the telephoto end.

The third lens group G ₃ moves along with the aperture stop S to the object side from the wide-angle end to the intermediate state by narrowing the distance from the second lens group G ₂ and widening the distance from the fourth lens group G _4. , from the intermediate state to the telephoto end, narrowing the distance between the second lens group G _2, it moves to the object side while narrowing the distance between the fourth lens group G _4. The third lens group G ₃ is located closer to the object side at the telephoto end than at the wide-angle end.

The fourth lens group G ₄ moves from the wide-angle end to the intermediate state and moves toward the object side while widening the distance from the third lens group G ₃ and widening the distance from the fifth lens group G _5, and from the intermediate state to the telephoto end. Until the distance from the third lens group G ₃ is narrowed, the distance from the fifth lens group G ₅ is increased, and the lens moves toward the object side. The telephoto end is located closer to the object side than the wide-angle end.

The fifth lens group G ₅ increases the distance from the fourth lens group G ₄ from the wide-angle end to the telephoto end, and moves only to the image side. The fifth lens group G ₅ is positioned closer to the image side than the wide angle end at the telephoto end.

The aspheric surfaces are the two surfaces r ₂₈ and r ₂₉ of the biconcave negative lens L ₄₂ of the fourth lens group G ₄ .

  FIG. 3 is a sectional view of the zoom lens according to the third embodiment.

As shown in FIG. 3, the zoom lens according to the third exemplary embodiment includes, in order from the object side to the image side, a first lens group G _{1 having} a positive refractive power, a second lens group G _{2 having} a negative refractive power, and a third lens having a positive refractive power. The lens unit includes a lens group G ₃ , a fourth lens group G _{4 having} a negative refractive power, and a fifth lens group G _{5 having} a positive refractive power. In the figure, S is the aperture stop, C is the cover glass, and I is the image plane.

The first lens group G ₁ has, in order from the object side to the image side, a positive meniscus lens L ₁₁ having a convex surface facing the object side, a negative meniscus lens L ₁₂ having a convex surface facing the object side, and a convex surface facing the object side. a cemented lens SU ₁₁ of the positive meniscus lens L _13, made of.

The second lens group G ₂ includes, in order from the object side to the image side, a biconvex positive lens L ₂₁ , a biconcave negative lens L ₂₂ , a cemented lens SU _{21 of} a positive meniscus lens L ₂₃ having a convex surface facing the object side, Concave negative lens L24.

The third lens group G ₃ includes a 3a lens group G _3a and a 3b lens group G _{3b in} order from the object side to the image side. The third-a lens group G _3a includes, in order from the object side to the image side, a biconvex positive lens L _3a1, and a cemented lens SU ₃₁ of the biconvex positive lens L _3a2 and the biconcave negative lens L _3a3 . Further, the 3b-th lens group G _3b, in order from the object side to the image side, a biconvex positive lens L _3b1, a biconvex positive lens L _3b2, a biconcave negative lens L _3b3, a biconvex positive lens L _3b4, Consists of.

The 3a lens group G _3a of the third lens group G ₃ and between the first 3b lens G _3b group, are disposed aperture stop S.

The fourth lens group G ₄ includes a biconvex positive lens L ₄₁ and a biconcave negative lens L ₄₂ .

G ₅ is the fifth lens group consists of one double-convex positive lens L _51.

  Next, the movement of each lens group when zooming from the wide-angle end to the telephoto end of the zoom lens of Example 3 will be described.

In the zoom operation, the first lens group G ₁ , the second lens group G ₂ , the third lens group G ₃ , the fourth lens group G ₄ , and the fifth lens group G ₅ move independently of each other.

The first lens group G ₁ moves from the wide-angle end to the telephoto end only at the object side by increasing the distance from the second lens group G ₂ . The first lens group G ₁ is located closer to the object side at the telephoto end than at the wide-angle end.

The second lens group G ₂ moves toward the image side from the wide-angle end to the telephoto end while widening the distance from the first lens group G ₁ and narrowing the distance from the third lens group G ₃ . The second lens group G ₂ is located closer to the image side than the wide-angle end at the telephoto end.

The third lens group G ₃ moves along with the aperture stop S to the object side from the wide-angle end to the intermediate state by narrowing the distance from the second lens group G ₂ and widening the distance from the fourth lens group G _4. , from the intermediate state to the telephoto end, narrowing the distance between the second lens group G _2, it moves to the object side while narrowing the distance between the fourth lens group G _4. The third lens group G ₃ is located closer to the object side at the telephoto end than at the wide-angle end.

The fourth lens group G ₄ moves from the wide-angle end to the intermediate state and moves toward the object side while widening the distance from the third lens group G ₃ and widening the distance from the fifth lens group G _5, and from the intermediate state to the telephoto end. Until the distance from the third lens group G ₃ is narrowed, the distance from the fifth lens group G ₅ is increased, and the lens moves toward the object side. The telephoto end is located closer to the object side than the wide-angle end.

The fifth lens group G _5, from the wide-angle end to the telephoto end, the spacing with the fourth lens unit G4, and moves only toward the image side. The fifth lens group G ₅ is positioned closer to the image side than the wide angle end at the telephoto end.

The aspheric surfaces are the two surfaces r ₂₈ and r ₂₉ of the biconcave negative lens L ₄₂ of the fourth lens group G ₄ .

  FIG. 4 is a cross-sectional view of the zoom lens of Example 4.

As shown in FIG. 4, the zoom lens of Example 4 includes, in order from the object side to the image side, a first lens group G _{1 having} a positive refractive power, a second lens group G _{2 having} a negative refractive power, and a third lens having a positive refractive power. The lens unit includes a lens group G ₃ , a fourth lens group G _{4 having} a negative refractive power, and a fifth lens group G _{5 having} a positive refractive power. In the figure, S is the aperture stop, C is the cover glass, and I is the image plane.

The first lens group G ₁ includes, in order from the object side to the image side, a planoconvex positive lens L ₁₁ having a convex surface facing the object side, a negative meniscus lens L ₁₂ having a convex surface facing the object side, and a convex surface facing the object side. and a cemented lens SU ₁₁ of the positive meniscus lens L _13, made of.

The second lens group G ₂ includes, in order from the object side to the image side, a positive meniscus lens L ₂₁ having a convex surface facing the image side, a biconcave negative lens L _22, and a positive meniscus lens L ₂₃ having a convex surface facing the object side. It consists of a lens SU ₂₁ and a biconcave negative lens L ₂₄ .

The third lens group G ₃ includes a 3a lens group G _3a and a 3b lens group G _{3b in} order from the object side to the image side. The third-a lens group G _3a includes, in order from the object side to the image side, a biconvex positive lens L _3a1, and a cemented lens SU ₃₁ of the biconvex positive lens L _3a2 and the biconcave negative lens L _3a3 . Further, the 3b-th lens group G _3b, in order from the object side to the image side, a biconvex positive lens L _3b1, a biconvex positive lens L _3b2, a biconcave negative lens L _3b3, a biconvex positive lens L _3b4, Consists of.

The 3a lens group G _3a of the third lens group G ₃ and between the 3b lens group G _3b, is disposed aperture stop S.

The fourth lens group G ₄ includes a biconvex positive lens L ₄₁ and a biconcave negative lens L ₄₂ .

G ₅ is the fifth lens group consists of one double-convex positive lens L _51.

  Next, the movement of each lens group when zooming from the wide-angle end to the telephoto end of the zoom lens of Example 4 will be described.

In the zoom operation, the first lens group G ₁ , the second lens group G ₂ , the third lens group G ₃ , the fourth lens group G ₄ , and the fifth lens group G ₅ move independently of each other.

The first lens group G ₁ moves from the wide-angle end to the telephoto end only at the object side by increasing the distance from the second lens group G ₂ . The first lens group G ₁ is located closer to the object side at the telephoto end than at the wide-angle end.

The second lens group G ₂ moves from the wide-angle end to the intermediate state toward the image side while increasing the distance from the first lens group G ₁ and narrowing the distance from the third lens group G _3, and from the intermediate state to the telephoto end. Until the first lens group G ₁ is widened and the distance from the third lens group G ₃ is narrowed. The second lens group G ₂ is located closer to the object side at the telephoto end than at the wide-angle end.

The third lens group G ₃ moves along with the aperture stop S to the object side from the wide-angle end to the intermediate state by narrowing the distance from the second lens group G ₂ and widening the distance from the fourth lens group G _4. , from the intermediate state to the telephoto end, narrowing the distance between the second lens group G _2, it moves to the object side while narrowing the distance between the fourth lens group G _4. The third lens group G ₃ is located closer to the object side at the telephoto end than at the wide-angle end.

The fourth lens group G ₄ moves from the wide-angle end to the intermediate state and moves toward the object side while widening the distance from the third lens group G ₃ and widening the distance from the fifth lens group G _5, and from the intermediate state to the telephoto end. Until the distance from the third lens group G ₃ is narrowed, the distance from the fifth lens group G ₅ is increased, and the lens moves toward the object side. The telephoto end is located closer to the object side than the wide-angle end.

The fifth lens group G ₅ increases the distance from the fourth lens group G ₄ from the wide-angle end to the telephoto end, and moves only to the image side. The fifth lens group G ₅ is positioned closer to the image side than the wide angle end at the telephoto end.

The aspheric surfaces are the two surfaces r ₂₈ and r ₂₉ of the biconcave negative lens L ₄₂ of the fourth lens group G ₄ .

  FIG. 5 is a cross-sectional view of the zoom lens of Example 5.

As shown in FIG. 5, the zoom lens of Example 5 includes, in order from the object side to the image side, a first lens group G _{1 having} a positive refractive power, a second lens group G _{2 having} a negative refractive power, and a third lens having a positive refractive power. The lens unit includes a lens group G ₃ , a fourth lens group G _{4 having} a negative refractive power, and a fifth lens group G _{5 having} a positive refractive power. In the figure, S is the aperture stop, C is the cover glass, and I is the image plane.

The first lens group G ₁ includes, in order from the object side to the image side, a biconvex positive lens L ₁₁ , a negative meniscus lens L ₁₂ having a convex surface facing the object side, and a positive meniscus lens L ₁₃ having a convex surface facing the object side. It consists of a cemented lens SU ₁₁ and a positive meniscus lens L ₁₄ with a convex surface facing the object side.

The second lens group G ₂ includes, in order from the object side to the image side, a positive meniscus lens L ₂₁ having a convex surface facing the image side, a biconcave negative lens L _22, and a positive meniscus lens L ₂₃ having a convex surface facing the object side. a lens SU21, a biconcave negative lens L _24, made of.

The third lens group G ₃ includes a 3a lens group G _3a and a 3b lens group G _{3b in} order from the object side to the image side. The third-a lens group G _3a includes, in order from the object side to the image side, a biconvex positive lens L _3a1, and a cemented lens SU ₃₁ of the biconvex positive lens L _3a2 and the biconcave negative lens L3a3. Further, the 3b-th lens group G _3b, in order from the object side to the image side, a biconvex positive lens L _3b1, a biconvex positive lens L _3b2, a biconcave negative lens L _3b3, a biconvex positive lens L _3b4, Consists of.

The 3a lens group G _3a of the third lens group G ₃ and between the 3b lens group G _3b, is disposed aperture stop S.

The fourth lens group G ₄ includes one biconcave negative lens L ₄₁ .

G ₅ is the fifth lens group consists of one double-convex positive lens L _51.

  Next, the movement of each lens group when zooming from the wide-angle end to the telephoto end of the zoom lens of Example 5 will be described.

In the zoom operation, the first lens group G ₁ , the second lens group G ₂ , the third lens group G ₃ , the fourth lens group G ₄ , and the fifth lens group G ₅ move independently of each other.

The first lens group G ₁ moves from the wide-angle end to the telephoto end only at the object side by increasing the distance from the second lens group G ₂ . The first lens group G ₁ is located closer to the object side at the telephoto end than at the wide-angle end.

The second lens group G ₂ moves from the wide-angle end to the intermediate state toward the image side while increasing the distance from the first lens group G ₁ and narrowing the distance from the third lens group G _3, and from the intermediate state to the telephoto end. Until the first lens group G ₁ is widened and the distance from the third lens group G ₃ is narrowed. The second lens group G ₂ is located closer to the image side than the wide-angle end at the telephoto end.

The third lens group G ₃ moves together with the aperture stop S to the object side from the wide-angle end to the telephoto end while narrowing the distance from the second lens group G ₂ and increasing the distance from the fourth lens group G _4. . The third lens group G ₃ is located closer to the object side at the telephoto end than at the wide-angle end.

The fourth lens group G ₄ moves toward the object side from the wide-angle end to the telephoto end while increasing the distance from the third lens group G ₃ and increasing the distance from the fifth lens group G ₅ . The telephoto end is located closer to the object side than the wide-angle end.

The fifth lens group G ₅ increases the distance from the fourth lens group G ₄ from the wide-angle end to the telephoto end, and moves only to the image side. The fifth lens group G ₅ is positioned closer to the image side than the wide angle end at the telephoto end.

The aspheric surfaces are the two surfaces r ₂₈ and r ₂₉ of the biconcave negative lens L ₄₂ of the fourth lens group G ₄ .

  FIG. 6 is a cross-sectional view of the zoom lens according to the sixth embodiment.

As shown in FIG. 6, the zoom lens of Example 6 includes, in order from the object side to the image side, a first lens group G _{1 having} a positive refractive power, a second lens group G _{2 having} a negative refractive power, and a third lens having a positive refractive power. The lens unit includes a lens group G ₃ , a fourth lens group G _{4 having} a negative refractive power, and a fifth lens group G _{5 having} a positive refractive power. In the figure, S is the aperture stop, C is the cover glass, and I is the image plane.

The first lens group G ₁ includes, in order from the object side to the image side, a biconvex positive lens L ₁₁ , a negative meniscus lens L ₁₂ having a convex surface facing the object side, and a positive meniscus lens L ₁₃ having a convex surface facing the object side. a cemented lens SU _11, made of.

The second lens group G ₂ includes, in order from the object side to the image side, a positive meniscus lens L ₂₁ having a convex surface facing the image side, a biconcave negative lens L _22, and a positive meniscus lens L ₂₃ having a convex surface facing the object side. It consists of a lens SU ₂₁ and a biconcave negative lens L ₂₄ .

The third lens group G ₃ includes a 3a lens group G _3a and a 3b lens group G _{3b in} order from the object side to the image side. The third-a lens group G _3a includes, in order from the object side to the image side, a biconvex positive lens L _3a1, and a cemented lens SU ₃₁ of the biconvex positive lens L _3a2 and the biconcave negative lens L _3a3 . Further, the 3b-th lens group G _3b, in order from the object side to the image side, a biconvex positive lens L _3b1, a biconvex positive lens L _3b2, a biconcave negative lens L _3b3, a biconvex positive lens L _3b4, Consists of.

The 3a lens group G _3a of the third lens group G ₃ and between the 3b lens group G _3b, is disposed aperture stop S.

The fourth lens group G ₄ includes a negative meniscus lens L ₄₁ having a convex surface directed toward the image side, and a biconcave negative lens L ₄₂ . The negative meniscus lens L ₄₁ and the biconcave negative lens L ₄₂ in the fourth lens group G ₄ are both resin lenses.

G ₅ is the fifth lens group consists of one double-convex positive lens L _51.

  Next, the movement of each lens group when zooming from the wide-angle end to the telephoto end of the zoom lens of Example 6 will be described.

In the zoom operation, the first lens group G ₁ , the second lens group G ₂ , the third lens group G ₃ , the fourth lens group G ₄ , and the fifth lens group G ₅ move independently of each other.

The first lens group G ₁ moves from the wide-angle end to the telephoto end only at the object side by increasing the distance from the second lens group G ₂ . The first lens group G ₁ is located closer to the object side at the telephoto end than at the wide-angle end.

The second lens group G ₂ moves from the wide-angle end to the intermediate state toward the image side while increasing the distance from the first lens group G ₁ and narrowing the distance from the third lens group G _3, and from the intermediate state to the telephoto end. Until the first lens group G ₁ is widened and the distance from the third lens group G ₃ is narrowed. The second lens group G ₂ is located closer to the image side than the wide-angle end at the telephoto end.

The third lens group G ₃ moves along with the aperture stop S to the object side from the wide-angle end to the intermediate state by narrowing the distance from the second lens group G ₂ and widening the distance from the fourth lens group G _4. , from the intermediate state to the telephoto end, narrowing the distance between the second lens group G _2, it moves to the object side while narrowing the distance between the fourth lens group G _4. The third lens group G ₃ is located closer to the object side at the telephoto end than at the wide-angle end.

The fourth lens group G ₄ moves toward the object side from the wide-angle end to the telephoto end while increasing the distance from the third lens group G ₃ and increasing the distance from the fifth lens group G ₅ . The telephoto end is located closer to the object side than the wide-angle end.

The fifth lens group G ₅ increases the distance from the fourth lens group G ₄ from the wide-angle end to the telephoto end, and moves only to the image side. The fifth lens group G ₅ is positioned closer to the image side than the wide angle end at the telephoto end.

The aspheric surfaces are the two surfaces r ₂₈ and r ₂₉ of the biconcave negative lens L ₄₂ of the fourth lens group G ₄ .

  Various numerical data (surface data, zoom data, and each group focal length) of the first to sixth embodiments are shown below.

  The surface data includes, for each surface number, the radius of curvature r of each lens surface (optical surface), the surface interval d, the refractive index nd of each lens (optical medium) with respect to the d-line (587.6 nm), and each lens (optical medium). The Abbe number νd of the d line is shown. The unit of the radius of curvature r and the surface interval d is millimeters (mm). In the surface data, “∞” described in the radius of curvature indicates infinite.

  In the aspherical surface data, data relating to a lens surface having an aspherical shape in the surface data is shown. The aspherical shape is expressed by the following equation, where x is an optical axis with the light traveling direction being positive, and y is a direction orthogonal to the optical axis.

x = (y ² / r) / [1+ {1− (1 + K) · (y / r) ² } ^1/2 ]
^{+ A4y 4 + A6y 6 + A8y} 8 + A10y 10 ...
Here, r is a paraxial radius of curvature, K is a conical coefficient, and A4, A6, and A8 are fourth-order, sixth-order, and eighth-order aspheric coefficients, respectively. The symbol “e” indicates that the subsequent numerical value is a power exponent with 10 as the base. For example, “1.0e-5” means “1.0 × 10 ⁻⁵ ”.

  The zoom data indicates the focal length, F number (FNO), angle of view 2ω (°), variable surface distance d, back focus (in air), total length (in air), and image height. The unit is millimeters (mm), except for the F number and the angle of view.

  WE indicates a wide angle end, ST indicates an intermediate state, and TE indicates a telephoto end.

Each group focal length data indicates focal lengths f1 to f5 in each lens group. All units are millimeters (mm).

Numerical example 1
Surface data surface number r d nd νd
1 97.453 5.95 1.49700 81.54
2 -1487.875 0.15
3 69.658 2.20 1.83400 37.16
4 42.507 9.45 1.49700 81.54
5 2152.996 D5 (variable)
6 -250.436 3.23 1.85026 32.27
7 -42.484 1.50 1.64850 53.02
8 20.736 3.50 1.78472 25.68
9 39.322 3.40
10 -56.724 1.10 1.88300 40.76
11 130.037 D11 (variable)
12 71.924 3.13 1.88300 40.76
13 -104.430 0.15
14 39.743 4.99 1.48749 70.23
15 -35.323 1.10 1.90366 31.32
16 104.250 16.03
17 (Aperture) ∞ 1.00
18 142.569 3.11 1.71736 29.52
19 -51.986 0.15
20 26.515 4.16 1.49700 81.54
21 -83.277 0.40
22 -94.899 1.40 1.90366 31.32
23 20.045 2.58
24 23.552 3.25 1.88300 40.76
25 1282.773 D25 (variable)
26 616.753 2.55 1.56732 42.82
27 -25.515 0.98
28 (Aspherical) -18.412 1.40 1.51633 64.14
29 (Aspherical) 16.530 D29 (Variable)
30 88.711 4.43 1.49700 81.54
31 -46.502 D31 (variable)
32 ∞ 3.50 1.51633 64.14
33 ∞ 0.80
Image plane ∞

Aspheric coefficient 28th surface
K = 0.000, A4 = 2.09223e-05, A6 = 5.75251e-08
29th page
K = 0.000, A4 = -1.60816e-05, A6 = -2.37245e-08

Zoom data
WE ST TE
Focal length 40.80 90.00 196.00
FNO. 4.08 4.08 4.08
Angle of view 2ω (°) 30.57 13.85 6.46
fb (in air) 31.51 27.21 24.06
Total length (in air) 158.58 170.08 193.58
Image height 11.15 11.15 11.15

D5 1.50 22.01 40.04
D11 38.72 15.20 1.50
D25 1.50 6.00 3.15
D29 4.04 18.34 43.52
D31 28.41 24.10 20.95

Each group focal length f1 107.04
f2 -28.68
f3 33.46
f4 -28.70
f5 62.06

Numerical example 2
Surface data surface number r d nd νd
1 101.119 5.05 1.49700 81.54
2 1291.484 0.15
3 80.138 2.20 1.83400 37.16
4 49.930 7.84 1.49700 81.54
5 842.939 D5 (variable)
6 231.944 3.67 1.85026 32.27
7 -43.793 1.50 1.64850 53.02
8 25.724 2.61 1.78472 25.68
9 40.631 3.25
10 -49.564 1.10 1.88300 40.76
11 112.688 D11 (variable)
12 83.274 2.90 1.88300 40.76
13 -99.579 1.43
14 39.419 5.13 1.48749 70.23
15 -28.536 1.10 1.90366 31.32
16 205.748 9.19
17 (Aperture) ∞ 1.00
18 254.457 3.17 1.71736 29.52
19 -40.119 0.15
20 27.676 3.71 1.49700 81.54
21 -134.378 0.49
22 -131.957 1.40 1.90366 31.32
23 20.307 3.55
24 24.351 3.15 1.88300 40.76
25 715.099 D25 (variable)
26 -728.533 2.48 1.56732 42.82
27 -24.850 1.07
28 (Aspherical surface) -17.929 1.40 1.51633 64.14
29 (Aspherical) 15.423 D29 (Variable)
30 88.592 4.33 1.49700 81.54
31 -40.328 D31 (variable)
32 ∞ 3.50 1.51633 64.14
33 ∞ 0.80
Image plane ∞

Aspheric coefficient 28th surface
K = 0.000, A4 = 2.18309e-05, A6 = 5.63538e-08
29th page
K = 0.000, A4 = -1.86188e-05, A6 = -6.82229e-08

Zoom data
WE ST TE
Focal length 40.80 90.00 196.00
FNO. 4.08 4.08 4.08
Angle of view 2ω (°) 30.45 13.86 6.48
fb (in air) 28.58 26.47 24.80
Total length (in air) 158.58 166.59 193.58
Image height 11.15 11.15 11.15

D5 1.50 24.95 52.42
D11 44.31 15.94 1.50
D25 1.50 6.37 3.68
D29 9.67 19.83 38.17
D31 25.48 23.37 21.69

Each group focal length f1 129.75
f2 -32.79
f3 31.22
f4 -25.65
f5 56.39

Numerical Example 3
Surface data surface number r d nd νd
1 107.113 4.93 1.49700 81.54
2 2559.681 0.15
3 91.779 2.20 1.83400 37.16
4 57.123 6.56 1.49700 81.54
5 384.113 D5 (variable)
6 142.743 3.43 1.85026 32.27
7 -49.378 1.50 1.64850 53.02
8 31.128 2.19 1.78472 25.68
9 44.645 4.44
10 -52.299 1.10 1.88300 40.76
11 150.581 D11 (variable)
12 68.251 2.65 1.88300 40.76
13 164.212 0.15
14 39.427 5.00 1.48749 70.23
15 -24.955 1.10 1.90366 31.32
16 980.577 1.50
17 (Aperture) ∞ 5.74
18 -12003.027 3.06 1.71736 29.5
19 -33.847 0.15
20 31.463 2.99 1.49700 81.54
21 -1667.310 0.75
22 -146.091 1.40 1.90366 31.32
23 19.685 3.17
24 24.212 3.27 1.88300 40.76
25 -249.661 D25 (variable)
26 467.288 2.47 1.56732 42.82
27 -29.908 1.98
28 (Aspherical surface) -17.840 1.40 1.51633 64.14
29 (Aspherical) 15.269 D29 (Variable)
30 101.854 4.18 1.49700 81.54
31 -37.040 D31 (variable)
32 ∞ 3.50 1.51633 64.14
33 ∞ 0.80
Image plane ∞

Aspheric coefficient 28th surface
K = 0.000, A4 = 3.17071e-05, A6 = 5.05279e-08
29th page
K = 0.000, A4 = -1.70752e-05, A6 = -8.08970e-08

Zoom data
WE ST TE
Focal length 40.80 90.00 196.00
FNO. 4.08 4.08 4.08
Angle of view 2ω (°) 30.55 13.85 6.46
fb (in air) 24.77 21.97 19.36
Total length (in air) 158.58 170.42 193.58
Image height 11.15 11.15 11.15

D5 1.50 35.60 67.80
D11 50.82 20.31 1.50
D25 1.50 4.33 1.50
D29 12.52 20.75 35.96
D31 21.67 18.87 16.26

Each group focal length f1 154.53
f2 -40.24
f3 30.11
f4 -24.86
f5 55.20

Numerical Example 4
Surface data surface number r d nd νd
1 95.275 5.73 1.49700 81.54
2 ∞ 0.15
3 71.428 2.20 1.83400 37.16
4 43.458 9.23 1.49700 81.54
5 2216.468 D5 (variable)
6 -264.923 3.32 1.85026 32.27
7 -37.048 1.50 1.64850 53.02
8 19.177 3.39 1.78472 25.68
9 36.463 3.40
10 -47.105 1.10 1.88300 40.76
11 118.246 D11 (variable)
12 113.134 2.90 1.88300 40.76
13 -72.421 0.15
14 33.332 5.53 1.48749 70.23
15 -27.653 1.10 1.90366 31.32
16 149.750 11.34
17 (Aperture) ∞ 1.00
18 247.265 3.37 1.71736 29.52
19 -39.456 0.15
20 26.021 4.27 1.49700 81.54
21 -78.391 0.43
22 -83.245 1.40 1.90366 31.32
23 20.014 2.94
24 24.202 3.29 1.88300 40.76
25 -1052.867 D25 (variable)
26 439.462 2.58 1.56732 42.82
27 -25.657 0.97
28 (Aspherical) -18.689 1.40 1.51633 64.14
29 (Aspherical) 16.578 D29 (Variable)
30 107.986 3.84 1.49700 81.54
31 -43.807 D31 (variable)
32 ∞ 11.26
33 ∞ 3.50 1.51633 64.14
34 ∞ 0.80
Image plane ∞

Aspheric coefficient 28th surface
K = 0.000, A4 = 1.93873e-05, A6 = 5.50715e-08
29th page
K = 0.000, A4 = -1.44766e-05, A6 = -2.39273e-08

Zoom data
WE ST TE
Focal length 40.80 90.00 196.00
FNO. 4.08 4.08 4.08
Angle of view 2ω (°) 30.62 13.85 6.46
fb (in air) 31.80 27.26 23.17
Total length (in air) 143.58 163.18 193.58
Image height 11.15 11.15 11.15

D5 1.50 23.40 44.76
D11 27.93 10.15 1.50
D25 1.50 6.80 3.02
D29 4.18 18.90 44.47
D31 17.44 12.89 8.80

Each group focal length f1 111.00
f2 -25.74
f3 30.14
f4 -29.36
f5 63.24

Numerical Example 5
Surface data surface number r d nd νd
1 103.876 5.67 1.49700 81.54
2 -2631.540 0.15
3 79.774 2.20 1.83400 37.16
4 47.161 7.58 1.49700 81.54
5 252.796 0.30
6 121.778 3.60 1.49700 81.54
7 733.098 D7 (variable)
8 -633.194 3.42 1.85026 32.27
9 -41.232 1.50 1.64850 53.02
10 19.725 3.22 1.78472 25.68
11 32.952 3.93
12 -40.157 1.10 1.88300 40.76
13 193.019 D13 (variable)
14 75.154 3.34 1.88300 40.76
15 -69.065 0.15
16 34.521 5.15 1.48749 70.23
17 -33.002 1.10 1.90366 31.32
18 128.340 12.38
19 (Aperture) ∞ 1.00
20 3309.944 2.98 1.71736 29.52
21 -35.980 0.15
22 32.272 3.12 1.49700 81.54
23 -179.542 0.92
24 -60.136 1.40 1.90366 31.32
25 26.762 9.17
26 36.209 2.69 1.88300 40.76
27 -561.553 D27 (variable)
28 (Aspherical) -122.128 1.00 1.49700 81.54
29 (Aspherical) 19.558 D29 (Variable)
30 47.017 4.18 1.49700 81.54
31 -61.610 D31 (variable)
32 ∞ 11.26
33 ∞ 3.50 1.51633 64.14
34 ∞ 0.80
Image plane ∞

Aspheric coefficient 28th surface
K = 0.000, A4 = -5.81185e-06, A6 = 3.20326e-08
29th page
K = 0.000, A4 = -1.58172e-05, A6 = 1.12238e-08, A6 = -4.42044e-11

Zoom data
WE ST TE
Focal length 40.80 90.00 196.00
FNO. 4.08 4.08 4.08
Angle of view 2ω (°) 30.61 13.85 6.48
fb (in air) 34.57 30.57 30.22
Total length (in air) 158.58 177.82 193.58
Image height 11.15 11.15 11.15

D5 1.20 25.04 39.41
D11 37.34 19.31 1.50
D25 1.80 8.56 11.45
D29 2.28 12.94 29.60
D31 20.20 16.20 15.85

Each group focal length f1 103.30
f2 -24.77
f3 37.66
f4 -33.84
f5 54.35

Numerical Example 6
Surface data surface number r d nd νd
1 100.320 5.80 1.49700 81.54
2 -1471.047 0.15
3 72.206 2.20 1.83400 37.16
4 44.302 8.93 1.49700 81.54
5 1014.530 D5
6 -392.593 3.24 1.85026 32.27
7 -44.457 1.50 1.64850 53.02
8 21.304 3.37 1.78472 25.68
9 39.557 3.38
10 -56.665 1.10 1.88300 40.76
11 124.127 D11
12 73.876 3.18 1.88300 40.76
13 -95.500 0.15
14 36.481 5.13 1.48749 70.23
15 -36.348 1.10 1.90366 31.32
16 85.108 15.26
17 (Aperture) ∞ 1.00
18 146.688 3.17 1.71736 29.52
19 -49.186 0.15
20 26.999 4.17 1.49700 81.54
21 -76.298 0.43
22 -81.203 1.40 1.90366 31.32
23 20.351 2.01
24 23.094 3.26 1.88300 40.76
25 705.547 D25
26 -182.934 2.23 1.58423 30.49
27 -26.283 0.88
28 (Aspherical) -20.955 ASP 1.40 1.52542 55.78
29 (Aspherical) 17.030 ASP D29
30 81.147 4.07 1.49700 81.54
31 -46.326 D31
32 ∞ 11.26
33 ∞ 3.50 1.51633 64.14
34 ∞ 0.80
Image plane ∞

Aspheric coefficient 28th surface
K = 0.000, A4 = 8.98528e-06, A6 = 3.02330e-08
29th page
K = 0.000, A4 = -1.44768e-05, A6 = -3.84457e-08

Zoom data
WE ST TE
Focal length 40.80 90.00 196.00
FNO. 4.08 4.08 4.08
Angle of view 2ω (°) 30.50 13.85 6.46
fb (in air) 32.12 27.94 24.44
Total length (in air) 158.58 168.72 193.58
Image height 11.15 11.15 11.15

D5 1.50 21.81 42.81
D11 40.17 14.81 1.50
D25 1.50 6.97 4.49
D29 4.65 18.55 41.70
D31 17.76 13.58 10.08

Each group focal length f1 112.89
f2 -29.38
f3 32.73
f4 -27.58
f5 59.97

7 to 12 are graphs showing various aberrations at (a) wide-angle end (WE), (b) intermediate state (ST), and (c) telephoto end (TE) in Examples 1 to 6. FIG.

  In these various aberration diagrams, SA represents spherical aberration, AS represents astigmatism, DT represents distortion, and CC represents lateral chromatic aberration. The spherical aberration SA is shown for each wavelength of 587.6 nm (d line: solid line), 435.8 nm (g line: one-dot chain line), and 656.3 nm (C line: broken line). The lateral chromatic aberration CC is shown for each wavelength of 435.8 nm (g line: one-dot chain line) and 656.3 nm (C line: broken line) with respect to the d line. Astigmatism DT, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. FNO indicates an F number.

About the said Examples 1-6, the value of each component and the value of each conditional expression (1)-(9) are shown below.

Example 1 Example 2 Example 3
Conditional expression (1) -0.703 -0.629 -0.609
Conditional expression (2) 0.259 0.228 0.194
Conditional expression (3) 2.624 3.180 3.787
Conditional expression (4) max 1.567 1.567 1.567
min 1.516 1.516 1.516
Conditional expression (5) max 2.57 2.57 2.57
min 2.52 2.52 2.52
Conditional expression (6) 0.820 0.765 0.738
Conditional expression (7) 0.312 0.298 0.311
Conditional expression (8) 3.256 2.996 2.441
Conditional expression (9) -0.146 -0.131 -0.127

Example 4 Example 5 Example 6
Conditional expression (1) -0.72 -0.829 -0.676
Conditional expression (2) 0.261 0.273 0.253
Conditional expression (3) 2.721 2.532 2.767
Conditional expression (4) max 1.567 1.883 1.584
min 1.516 1.497 1.525
Conditional expression (5) max 2.57 3.57 1.2
min 2.52 3.57 1.01
Conditional expression (6) 0.739 0.923 0.802
Conditional expression (7) 0.312 0.323 0.309
Conditional expression (8) 2.978 3.305 3.209
Conditional expression (9) -0.15 -0.173 -0.141

In the zoom lens of the present embodiment, a flare stop other than the brightness stop may be arranged in order to cut unnecessary light such as ghosts and flares. Object side of the first lens group, between the first lens group and the second lens group, between the second lens group and the third lens group, between the third lens group and the fourth lens group, and between the fourth lens group and the fifth lens group. Between the fifth lens group and the image plane.

  Moreover, you may comprise so that a flare ray may be cut with a frame member, and you may comprise another member. The flare stop may be printed directly on the optical system, painted, or bonded with a seal. The shape of the flare stop may be any shape such as a circle, an ellipse, a rectangle, a polygon, or a range surrounded by a function curve. Further, not only harmful light beams but also light beams such as coma flare around the screen may be cut.

  Each lens may be provided with an anti-reflection coating to reduce ghosts and flares. A multi-coat is desirable because it can effectively reduce ghost and flare. An infrared cut coat may be used for the lens surface, cover glass, and the like. The brightness (shading) at the periphery of the image may be reduced by shifting the micro lens of the CCD. For example, the design of the CCD microlens may be changed according to the incident angle of the light beam at each image height. Further, the amount of decrease in the peripheral portion of the image may be corrected by image processing.

  In order to prevent the occurrence of ghost and flare, it is common practice to apply an antireflection coating to the air contact surface of the lens. On the other hand, the refractive index of the adhesive is sufficiently higher than the refractive index of air on the cemented surface of the cemented lens. For this reason, the reflectance is often the same as or lower than that of a single-layer coating, and it is rare to apply a coating. However, if an anti-reflection coating is also applied to the joint surface, ghosts and flares can be further reduced, and still better images can be obtained. In recent years, high refractive index glass materials have become widespread and have been used extensively in camera optical systems due to their high aberration correction effects. However, when high refractive index glass materials are used as cemented lenses, reflection on the cemented surface is ignored. It becomes impossible. In such a case, it is particularly effective to provide an antireflection coating on the joint surface.

  Effective use of the bonding surface coat is disclosed in JP-A-2-27301, JP-A-2001-324676, JP-A-2005-92115, USP7116482, and the like. These documents particularly describe the cemented lens surface coating in the first lens group of the positive leading zoom lens, and the cemented lens surface in the first lens group of the present invention is also implemented as disclosed in these documents. That's fine.

As a coating material to be used, Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , ZrO ₂ , HfO ₂ , CeO having a relatively high refractive index is selected according to the refractive index of the base lens and the refractive index of the adhesive. ₂ , coating material such as SnO ₂ , In ₂ O ₃ , ZnO, Y ₂ O ₃ , coating material such as MgF ₂ , SiO ₂ , Al ₂ O _{3 with} relatively low refractive index, etc. The film thickness may be set so as to satisfy the above.

  As a matter of course, the coating on the bonding surface may be a multi-coat as in the case of the coating on the air contact surface of the lens. By appropriately combining two or more layers of coating materials and film thicknesses, it becomes possible to further reduce the reflectance and control the spectral characteristics and angular characteristics of the reflectance. Needless to say, it is effective to coat the cemented surfaces other than the first lens group based on the same concept.

  FIG. 13 is a cross-sectional view of a single-lens mirrorless camera as an image pickup apparatus using the zoom lens of the present embodiment and using a small CCD or CMOS as an image pickup device. In FIG. 13, reference numeral 1 denotes a single lens mirrorless camera, 2 denotes an imaging lens system disposed in the lens barrel, 3 denotes a lens barrel mounting portion that allows the imaging lens system 2 to be attached to and detached from the single lens mirrorless camera 1, and a screw A mount of type or bayonet type is used. In this example, a bayonet type mount is used. Reference numeral 4 denotes an image sensor surface, and 5 denotes a back monitor.

 As the imaging lens system 2 of the single-lens mirrorless camera 1 having such a configuration, for example, the zoom lens of the present embodiment shown in Examples 1 to 6 is used.

  14 and 15 are conceptual diagrams of the configuration of the imaging apparatus according to the present embodiment in which a zoom lens is incorporated in the photographing optical system 41. FIG. FIG. 14 is a front perspective view showing the appearance of a digital camera 40 as an image pickup apparatus, and FIG. 15 is a rear perspective view of the same.

  The digital camera 40 of this embodiment includes a photographing optical system 41 positioned on the photographing optical path 42, a shutter button 45, a liquid crystal display monitor 47, and the like. When the shutter button 45 disposed on the upper part of the digital camera 40 is pressed, In conjunction with this, photographing is performed through the photographing optical system 41, for example, the lens system of the first embodiment. An object image formed by the photographing optical system 41 is formed on an image sensor (photoelectric conversion surface) provided in the vicinity of the imaging surface. The object image received by the image sensor is displayed on the liquid crystal display monitor 47 provided on the back of the camera as an electronic image by the processing means. In addition, the photographed electronic image can be recorded in a recording unit.

  FIGS. 16 to 18 are conceptual diagrams of configurations of other imaging apparatuses in which a zoom lens is incorporated in the photographing optical system 41. FIG. 16 is a front perspective view showing the appearance of the digital camera 40, FIG. 17 is a rear view thereof, and FIG. 18 is a schematic cross-sectional view showing the configuration of the digital camera 40.

  In this example, the digital camera 40 includes a photographic optical system 41 positioned on the photographic optical path 42, a finder optical system 43 positioned on the finder optical path 44, a shutter button 45, a pop-up flash 46, a liquid crystal display monitor 47, and the like. In addition, when a shutter button 45 disposed on the upper portion of the camera 40 is pressed, photographing is performed through the photographing optical system 41, for example, the lens of the first embodiment, in conjunction therewith. The object image formed by the photographing optical system 41 is formed on the image pickup surface (photoelectric conversion surface) of the CCD 49 as an image pickup element provided in the vicinity of the image forming surface. The object image received by the CCD 49 is displayed as an electronic image on the liquid crystal display monitor 47 provided on the back of the camera or the finder image display element 54 via the processing means 51. Further, the processing means 51 is connected to a recording means 52 so that a photographed electronic image can be recorded.

  The recording unit 52 may be provided separately from the processing unit 51, or may be configured to perform recording and writing electronically using a flexible disk, a memory card, an MO, or the like. Further, it may be configured as a silver salt camera in which a silver salt film is arranged in place of the CCD 49.

  Further, a finder eyepiece lens 59 is disposed on the finder optical path 44. The object image displayed on the finder image display element 54 is magnified by the finder eyepiece lens 59 and adjusted to a diopter that is easy for the observer to see, and is guided to the observer eyeball E. A cover member 50 is disposed on the exit side of the finder eyepiece lens 59.

  FIG. 19 is a block diagram showing an internal circuit of a main part of the digital camera 40 of the present embodiment. In the following description, the processing unit 51 described above is configured by, for example, the CDS / ADC unit 24, the temporary storage memory 17, the image processing unit 18, and the like, and the storage unit 52 is configured by a storage medium unit or the like.

  As shown in FIG. 19, the digital camera 40 is connected to the operation unit 12, the control unit 13 connected to the operation unit 12, and the control signal output port of the control unit 13 via buses 14 and 15. The imaging drive circuit 16, the temporary storage memory 17, the image processing unit 18, the storage medium unit 19, the display unit 20, and the setting information storage memory unit 21 are provided.

  The temporary storage memory 17, the image processing unit 18, the storage medium unit 19, the display unit 20, and the setting information storage memory unit 21 can mutually input and output data via the bus 22. In addition, a CCD 49 and a CDS / ADC unit 24 are connected to the imaging drive circuit 16.

  The operation unit 12 includes various input buttons and switches, and notifies the control unit of event information input from the outside (camera user) via these buttons. The control unit 13 is a central processing unit composed of, for example, a CPU, and has a built-in program memory (not shown) and controls the entire digital camera 40 according to a program stored in the program memory.

  The CCD 49 is an image pickup device that is driven and controlled by the image pickup drive circuit 16, converts the light amount of each pixel of the object image formed via the image pickup optical system 41 into an electric signal, and outputs the electric signal to the CDS / ADC unit 24.

  The CDS / ADC unit 24 amplifies the electric signal input from the CCD 49, performs analog / digital conversion, and performs raw video data (Bayer data, hereinafter referred to as RAW data) obtained by performing the amplification and digital conversion. ) To the temporary memory 17.

  The temporary storage memory 17 is a buffer made of, for example, SDRAM, and is a memory device that temporarily stores RAW data output from the CDS / ADC unit 24. The image processing unit 18 reads out the RAW data stored in the temporary storage memory 17 or the RAW data stored in the storage medium unit 19, and includes distortion correction based on the image quality parameter designated by the control unit 13. It is a circuit that performs various image processing electrically.

  The storage medium unit 19 is detachably mounted with a card-type or stick-type storage medium made of, for example, a flash memory, and the RAW data transferred from the temporary storage memory 17 and the image processing unit 18 to these flash memories. Image-processed image data is recorded and held.

  The display unit 20 includes a liquid crystal display monitor 47 and the like, and displays captured RAW data, image data, an operation menu, and the like. The setting information storage memory unit 21 includes a ROM unit that stores various image quality parameters in advance, and a RAM unit that stores image quality parameters read from the ROM unit by an input operation of the operation unit 12.

  By adopting the zoom lens of the present invention as the imaging optical system 41, the digital camera 40 configured in this way can be a small imaging device suitable for moving image imaging.

  Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and embodiments configured by appropriately combining the configurations of the respective embodiments also fall within the scope of the present invention. Is.

DESCRIPTION OF SYMBOLS 1 ... Lens interchangeable camera 2 ... Imaging lens system 3 ... Mount part 4 ... Image pick-up element surface 5 ... Back monitor 12 ... Operation part 13 ... Control part 14, 15 ... Bus | bath 16 ... Imaging drive circuit 17 ... Temporary memory 18 ... Image Processing unit 19 ... Storage medium unit 20 ... Display unit 21 ... Setting information storage memory unit 22 ... Bus 24 ... CDS / ADC unit 40 ... Digital camera 41 ... Shooting optical system 42 ... Shooting optical path 45 ... Shutter button 47 ... Liquid crystal display monitor

Claims (15)

From the object side to the image side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having negative refractive power;
A fifth lens group having positive refractive power;
Consists of
The first lens group includes:
Consists of three or more lenses,
The third lens group in order from the object side to the image side,
It consists of a 3a lens group and a 3b lens group,
The 3a lens group includes a positive lens and a negative lens,
The third lens group includes a positive lens and a negative lens,
The fourth lens group includes:
Consists of two or less lenses,
Moving the first lens group at the time of zooming from the wide-angle end to the telephoto end;
Move the fourth lens group during focusing,
A zoom lens satisfying the following conditional expression (1) and conditional expression (2A):
_{-0.8 <f 4 / f W <} -0.3 ··· (1)
0.15 < _dG3 / _LW <0.4 (2A)
However,
f _W is the focal length of the entire zoom lens system at the wide-angle end,
f ₄ is the focal length of the fourth lens group,
d _G3 is the thickness of the third lens group on the optical axis,
L _W is the total length of the entire zoom lens system at the wide-angle end,
It is. From the object side to the image side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having negative refractive power;
A fifth lens group having positive refractive power;
Consists of
The first lens group includes:
Consists of three or more lenses,
The third lens group in order from the object side to the image side,
It consists of a 3a lens group and a 3b lens group
The 3a lens group includes a positive lens and a negative lens,
The third lens group includes a positive lens and a negative lens,
The fourth lens group is composed of two or less lenses,
Moving the first lens group at the time of zooming from the wide-angle end to the telephoto end;
Move the fourth lens group during focusing,
A zoom lens satisfying the following conditional expression (1), conditional expression (3), and conditional expression (8):
_{-0.8 <f 4 / f W <} -0.3 ··· (1)
_{2 <f 1 / f W <} 4 ··· (3)
1.9 < _dG3 / _dG2 <5 (8)
However,
f _W is the focal length of the entire zoom lens system at the wide-angle end,
f ₄ is the focal length of the fourth lens group,
f ₁ is the focal length of the first lens group,
d _G2 is the thickness of the second lens group on the optical axis,
d _G3 is the thickness of the third lens group on the optical axis,
It is. From the object side to the image side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having negative refractive power;
A fifth lens group having positive refractive power;
Consists of
The first lens group includes:
Consists of three or more lenses,
The third lens group in order from the object side to the image side,
It consists of a 3a lens group and a 3b lens group,
The 3a lens group includes a positive lens and a negative lens,
The third lens group includes a positive lens and a negative lens,
The fourth lens group includes:
Consists of two or less lenses,
When zooming from the wide-angle end to the telephoto end,
Moving the first lens group;
Moving the third lens group to the object side monotonously;
Move the fourth lens group during focusing,
A zoom lens that satisfies the following conditional expressions (1) and (8):
_{-0.8 <f 4 / f W <} -0.3 ··· (1)
1.9 < _dG3 / _dG2 <5 (8)
However,
f _W is the focal length of the entire zoom lens system at the wide-angle end,
f ₄ is the focal length of the fourth lens group,
d _G2 is the thickness of the second lens group on the optical axis,
d _G3 is the thickness of the third lens group on the optical axis,
It is. 4. The zoom lens according to claim 1, wherein the fourth lens group includes at least one refractive optical element that satisfies the following conditional expression (4): 5.
1.4 <nd (LD) <1.6 (4)
Where nd (LD) is the refractive index of the refractive optical element. The zoom lens according to any one of claims 1 to 4, wherein the following conditional expression (5) is satisfied.
1 <ρ ₄ <3.7 (5)
Here, ρ ₄ is the specific gravity of the lens in the fourth lens group. The zoom lens according to claim 1, wherein the following conditional expression (6) is satisfied.
_{0.5 <f 3 / f W <} 0.9 ··· (6)
Here, f ₃ is the focal length of the third lens group. The zoom lens according to any one of claims 1 to 6, wherein the second lens group includes a lens having a refractive index of 1.85 or more. 8. The zoom lens according to claim 1, wherein at least one lens surface of the fourth lens group is an aspherical surface. 9. The zoom lens according to any one of claims 1 to 8, wherein the following conditional expression (7) is satisfied.
_{0.2 <d G2 / f W <} 0.5 ··· (7)
Here, d _G2 is the thickness on the optical axis of the second lens group. The zoom lens according to claim 1, wherein the fourth lens group includes a resin lens. The zoom lens according to any one of claims 1 to 10, wherein the fourth lens group includes a single lens. The third lens group has an aperture stop,
The zoom according to any one of claims 1 to 11, wherein the aperture stop moves together with the third lens group at the time of zooming from the wide-angle end to the telephoto end. lens. The zoom lens according to claim 1, wherein the following conditional expression (8) is satisfied.
1.9 < _dG3 / _dG2 <5 (8) The zoom lens according to any one of claims 1 to 13, wherein the following conditional expression (9) is satisfied.
_{-0.25 <f 4 / f t <} -0.05 ··· (9)
Here, _ft is the focal length of the entire zoom lens system at the telephoto end. A zoom lens according to any one of claims 1 to 14,
An image pickup apparatus body having an image pickup element disposed on the image side of the zoom lens and having an image pickup surface for receiving an image from the zoom lens;
An imaging apparatus comprising:

Images