JP2010032702A - Zoom lens, optical device comprising the same, and power variation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an image shift by an optical system movable so as to have a component in a direction orthogonal to the optical axis, enable camera shake correction, and provide an appropriate lens group so as to reduce performance deterioration while achieving high zooming A zoom lens in which the refractive power is set, an optical apparatus having the same, and a zooming method are provided.
A first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, arranged in order from the object side, It has a fourth lens group G4 having negative refractive power and a fifth lens group G5 having positive refractive power, and at least a part of the lens group GA of the fourth lens group G4 has a component perpendicular to the optical axis. The distance between the lens groups changes upon zooming from the wide-angle end state to the telephoto end state, the focal length G5 of the fifth lens group is f5, and the entire lens system is in focus at infinity. When the focal length in the telephoto end state is ft, the following condition 0.01 <f5 / ft <0.30 is satisfied.
[Selection] Figure 1

Description

  The present invention relates to a zoom lens, an optical apparatus having the same, and a zooming method.

Conventionally, zoom lenses having a camera shake correction function suitable for photographic cameras, electronic still cameras, video cameras, and the like have been proposed (see, for example, Patent Document 1).
JP 2006-227526 A

  However, in the conventional zoom lens, a mechanism for correcting camera shake must be incorporated in the lens barrel, and the compactness tends to be lost in the overall length and outer diameter of the lens barrel. In addition, a zoom lens having a camera shake correction function has a problem that optical performance is significantly deteriorated when zooming is performed at a high magnification.

  The present invention has been made in view of such a problem, and performs image shift by an optical system that can move so as to have a component orthogonal to the optical axis, enables camera shake correction, and achieves high zooming. An object of the present invention is to provide a zoom lens in which the refractive power of an appropriate lens group is set so as to reduce the deterioration of performance while aiming, an optical apparatus having the zoom lens, and a zooming method.

  In order to achieve such an object, the zoom lens of the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refraction arranged in order from the object side. A third lens group having power, a fourth lens group having negative refracting power, and a fifth lens group having positive refracting power, and at least a part of the lens group of the fourth lens group is irradiated with light. When the zoom lens is moved so as to have a component orthogonal to the axis, the distance between the lens groups changes upon zooming from the wide-angle end state to the telephoto end state, and the focal length of the fifth lens group is f5. When the focal length in the telephoto end state at the time of focusing on infinity is ft, the following condition 0.01 <f5 / ft <0.30 is satisfied.

  When the focal length of the second lens group is f2 and the focal length of the fourth lens group is f4, the condition of the following formula 0.577 <(− f2) / (− f4) <1.200 is satisfied. It is preferable to satisfy.

  Further, when the focal length of the fourth lens group is f4 and the focal length is ft in the telephoto end state when the entire lens system is focused at infinity, the following expression 0.01 <(− f4) / ft <0. It is preferable to satisfy 25 conditions.

  The fourth lens group includes a lens group GA having a negative refractive power and a lens group GB which is disposed adjacent to the image side of the lens group GA and has a negative refractive power. preferable.

  The lens group GB preferably includes at least one aspheric surface.

  Further, when the focal length of the lens group moving so as to have a component orthogonal to the optical axis is fA, and the focal length in the telephoto end state when the entire lens system is focused at infinity is ft, the following equation 0 .05 <(− fA) / ft <0.40 is preferably satisfied.

  Further, when the focal length of the fourth lens group is f4 and the focal length of the fifth lens group is f5, the following expression 1.10 <f5 / (− f4) <2.00 is satisfied. Is preferred.

  Further, when the focal length of the fifth lens group is f5 and the focal length in the wide-angle end state at the time of focusing on infinity of the entire lens system is fw, the following expression 0.11 <f5 / fw <3.20 is satisfied. It is preferable to satisfy the conditions.

  The fourth lens group preferably has a cemented lens.

  Further, when zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases. Preferably, the distance between the third lens group and the fourth lens group is increased, and the distance between the fourth lens group and the fifth lens group is decreased.

  Further, it is preferable that the third lens group and the fifth lens group move together when zooming from the wide-angle end state to the telephoto end state.

  The third lens group preferably includes three lens groups having a positive refractive power, and the three lens groups include at least two cemented lenses.

  Further, focusing from an infinitely distant object to a close object is preferably performed by moving at least a part of the second lens group in the optical axis direction.

  The optical apparatus of the present invention has the zoom lens described above.

  Further, the present invention provides a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a negative lens arranged in order from the object side. A zoom lens zooming method comprising a fourth lens group having a refractive power of 5 and a fifth lens group having a positive refractive power, wherein at least a part of the lens group GA of the fourth lens group is moved along an optical axis. The distance between the lens groups changes upon zooming from the wide-angle end state to the telephoto end state, the focal length of the fifth lens group is f5, and the entire lens system is infinite. When the focal length in the telephoto end state at the time of far focusing is ft, the following equation 0.01 <f5 / ft <0.30 is satisfied.

  According to the present invention, image shift is performed by an optical system that can move so as to have a component orthogonal to the optical axis, image stabilization is possible, and it is appropriate to reduce performance deterioration while achieving high zooming. It is possible to provide a zoom lens in which the refractive power of various lens groups is set, an optical apparatus having the same, and a zooming method.

  Hereinafter, preferred embodiments will be described with reference to the drawings. As shown in FIG. 1, the zoom lens according to the present embodiment includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive lens arranged in order from the object side. A third lens group G3 having a refractive power; a fourth lens group G4 having a negative refractive power; and a fifth lens group G5 having a positive refractive power; and at least a part of the fourth lens group G4. By moving the lens group so as to have a component in a direction orthogonal to the optical axis, image plane correction when camera shake occurs is performed.

  In the present embodiment, the fourth lens group G4 has a smaller number of constituent lenses than the other lens groups, and the lens diameter can be reduced. Therefore, the fourth lens group G4 is suitable for incorporating a camera shake correction mechanism. With this configuration, it is possible to reduce the size of the lens barrel, and it is possible to satisfactorily correct aberration fluctuations accompanying camera shake correction.

  Based on the above configuration, when the focal length of the fifth lens group G5 is f5, and the focal length in the telephoto end state when the entire lens system is in focus at infinity is ft, the condition of the following expression (1) is satisfied. Satisfied.

  0.01 <f5 / ft <0.30 (1)

  Conditional expression (1) defines the focal length f5 of the fifth lens group G5 with respect to the focal length ft in the telephoto end state. By satisfying the conditional expression (1), the present zoom lens can reduce the burden on aberrations and zooming to other lens groups other than the fifth lens group G5, thus realizing good optical performance. In addition, a predetermined zoom ratio can be ensured. If the upper limit of conditional expression (1) is exceeded, the refractive power of the fifth lens group G5 becomes too weak, and the refractive power of the other lens groups becomes strong in order to ensure the zoom ratio, and the spherical surface in the telephoto end state. It becomes difficult to correct aberrations. On the other hand, if the lower limit of conditional expression (1) is not reached, the refractive power of the fifth lens group G5 becomes too strong, making it difficult to correct coma in the wide-angle end state.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 0.24. Accordingly, the focal length of the fifth lens group G5 can be more appropriately arranged, and spherical aberration in the telephoto end state can be corrected more favorably. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.05. Thereby, the focal length of the fifth lens group G5 can be more appropriately arranged, and coma aberration in the wide-angle end state can be corrected more favorably.

  In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.175. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.10.

  In the present embodiment, it is preferable that the condition of the following expression (2) is satisfied when the focal length of the second lens group G2 is f2 and the focal length of the fourth lens group G4 is f4.

  0.577 <(− f2) / (− f4) <1.200 (2)

  Conditional expression (2) defines the focal length f2 of the second lens group G2 with respect to the focal length f4 of the fourth lens group G4. The present zoom lens can satisfy the conditional expression (2), thereby realizing good optical performance and ensuring a predetermined zoom ratio. If the upper limit value of conditional expression (2) is exceeded, the refractive power of the second lens group G2 becomes too weak, and it becomes difficult to ensure the amount of peripheral light in the wide-angle end state. If the refractive powers of the other lens groups are increased to alleviate this influence, it becomes difficult to correct spherical aberration in the telephoto end state. On the other hand, if the lower limit of conditional expression (2) is not reached, the refractive power of the second lens group G2 becomes too strong, and the field curvature and astigmatism in the wide-angle end state deteriorate.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 1.000. Accordingly, the focal lengths of the second lens group G2 and the fourth lens group G4 can be more appropriately arranged, and spherical aberration in the telephoto end state can be corrected more favorably. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.580. Thereby, the focal lengths of the second lens group G2 and the fourth lens group G4 can be more appropriately arranged, and field curvature and astigmatism in the wide-angle end state can be corrected more favorably.

  In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.900. In order to further secure the effect of the present embodiment, it is more preferable to set the lower limit value of conditional expression (2) to 0.590.

  In the present embodiment, when the focal length of the fourth lens group G4 is f4 and the focal length is ft in the telephoto end state when the entire lens system is focused at infinity, the condition of the following expression (3) is satisfied. It is preferable to do.

  0.01 <(− f4) / ft <0.25 (3)

  Conditional expression (3) defines the focal length f4 of the fourth lens group G4 with respect to the focal length ft in the telephoto end state. By satisfying conditional expression (3), this zoom lens can realize good optical performance and ensure a predetermined zoom ratio. If the upper limit value of conditional expression (3) is exceeded, the refractive power of the fourth lens group G4 becomes too weak, and the shift amount of the fourth lens group G4 increases in order to correct camera shake. In addition, it is difficult to correct astigmatism fluctuations during camera shake correction. On the other hand, if the lower limit of conditional expression (3) is not reached, the refractive power of the fourth lens group G4 becomes strong, and it becomes difficult to correct spherical aberration in the telephoto end state.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to 0.18. As a result, the focal length of the fourth lens group G4 can be more appropriately arranged, and fluctuations in astigmatism during camera shake correction can be suppressed more favorably. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to 0.02. Thereby, the focal length of the fourth lens group G4 can be more appropriately arranged, and spherical aberration in the telephoto end state can be corrected more favorably.

  In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to 0.135. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to 0.05.

  In the present embodiment, the fourth lens group G4 includes the lens group GA having a negative refractive power and the lens group GB that is disposed adjacent to the image side of the lens group GA and has a negative refractive power. It is preferable to have. Furthermore, it is preferable that the lens group GB includes at least one aspheric surface. Thereby, it is possible to simultaneously correct the fluctuation of the curvature of field at the time of camera shake correction in the telephoto end state and the fluctuation of the eccentric coma aberration.

  In this embodiment, the focal length of the lens group, which is a vibration-proof lens group that moves so as to have a component orthogonal to the optical axis, is fA, and the telephoto end state when the entire lens system is focused at infinity When the focal length at is ft, it is preferable to satisfy the condition of the following expression (4).

  0.05 <(− fA) / ft <0.40 (4)

  The conditional expression (4) defines the focal length fA of the lens unit that is the image stabilizing lens unit with respect to the focal length ft in the telephoto end state. By satisfying the conditional expression (4), the present zoom lens can ensure optical performance during camera shake correction and reduce optical performance degradation due to manufacturing errors. If the upper limit of conditional expression (4) is exceeded, the refractive power of the lens group that is the anti-vibration lens group becomes weak, the shift amount of the lens group becomes large, and fluctuations in astigmatism during camera shake correction occur. It becomes difficult to correct. On the other hand, if the lower limit value of the conditional expression (4) is not reached, the refractive power of the lens group which is an anti-vibration lens group becomes strong, the manufacturing error becomes sensitive, and correction of spherical aberration in the telephoto end state becomes difficult. .

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 0.08. As a result, the focal length fA of the lens group that is the anti-vibration lens group can be more appropriately arranged, and spherical aberration in the telephoto end state can be corrected more favorably. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 0.30. As a result, the focal length fA of the lens group that is the anti-vibration lens group can be arranged more appropriately, and astigmatism fluctuations during camera shake correction can be corrected better.

  In the present embodiment, it is preferable that the condition of the following expression (5) is satisfied when the focal length of the fourth lens group G4 is f4 and the focal length of the fifth lens group G5 is f5.

  1.10 <f5 / (− f4) <2.00 (5)

  Conditional expression (5) defines the focal length f5 of the fifth lens group G5 with respect to the focal length f4 of the fourth lens group G4. The zoom lens satisfies the conditional expression (5), thereby realizing good optical performance and ensuring a predetermined zoom ratio. If the upper limit value of conditional expression (5) is exceeded, the refractive power of the fourth lens group G4 becomes too strong, the decentering coma during camera shake correction increases, and the field curvature fluctuations also increase. On the other hand, if the lower limit of conditional expression (5) is not reached, the refractive power of the fifth lens group G5 becomes too strong, and coma, curvature of field, and distortion become large.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 1.80. As a result, the focal length f4 of the fourth lens group G4 and the focal length f5 of the fifth lens group G5 can be more appropriately arranged, the decentering coma aberration during camera shake correction can be further reduced, and the image plane The bending fluctuation can be further reduced. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 1.20. Accordingly, the focal length f4 of the fourth lens group G4 and the focal length f5 of the fifth lens group G5 can be more appropriately arranged, and coma aberration, field curvature, and distortion aberration can be corrected more favorably. it can.

  In the present embodiment, when the focal length of the fifth lens group G5 is f5 and the focal length at the wide-angle end state when the entire lens system is focused at infinity is fw, the condition of the following equation (6) is satisfied. It is preferable to satisfy.

  0.11 <f5 / fw <3.20 (6)

  Conditional expression (6) defines the focal length f5 of the fifth lens group G5 with respect to the focal length fw in the wide-angle end state of the entire lens system. The zoom lens can satisfy the conditional expression (6), thereby realizing good optical performance and ensuring a predetermined zoom ratio. If the upper limit of conditional expression (6) is exceeded, the refractive power of the fifth lens group G5 becomes too weak, and the refractive power of the other lens groups becomes strong to secure the zoom ratio, and the spherical surface in the telephoto end state. It becomes difficult to correct aberrations. On the other hand, if the lower limit of conditional expression (6) is not reached, the refractive power of the fifth lens group G5 becomes too strong, making it difficult to correct coma in the wide-angle end state.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (6) to 2.60. Accordingly, the focal length f5 of the fifth lens group G5 can be more appropriately arranged with respect to the focal length fw of the wide-angle end state of the entire lens system, and spherical aberration in the telephoto end state can be corrected more favorably. it can. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (6) to 0.50. Thereby, the focal length f5 of the fifth lens group G5 can be more appropriately arranged with respect to the focal length fw of the wide-angle end state of the entire lens system, and coma aberration in the wide-angle end state can be corrected more favorably. it can.

  In the present embodiment, it is preferable that the fourth lens group G4 has a cemented lens. With this configuration, both axial chromatic aberration and lateral chromatic aberration can be corrected well.

  In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 0.10. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 0.25.

  In the present embodiment, when zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens G2 increases, and the second lens group G2 and the third lens group G3 Preferably, the distance between the third lens group G3 and the fourth lens group G4 increases, and the distance between the fourth lens group G4 and the fifth lens group G5 decreases. As a result, it is possible to ensure a predetermined zoom ratio while effectively correcting variations in spherical aberration and field curvature.

  In the present embodiment, it is preferable that the third lens group G3 and the fifth lens group G5 move together when zooming from the wide-angle end state to the telephoto end state. As a result, it is possible to reduce the deterioration in performance due to the eccentricity of the fifth lens group G5 at the time of manufacture while ensuring a predetermined zoom ratio.

  In the present embodiment, the third lens group G3 preferably includes three lens groups having a positive refractive power, and these three lens groups preferably include at least two cemented lenses. Thereby, the field curvature in the wide-angle end state and the spherical aberration in the telephoto end state can be corrected simultaneously.

  In the present embodiment, it is preferable that focusing from an object at infinity to an object at a short distance is performed by moving at least a part of the second lens group G2 in the optical axis direction. Thereby, fluctuations in spherical aberration, curvature of field, and the like during focusing on a short-distance object can be reduced. Further, by using the small lens group as the focusing lens group, it is possible to focus quickly.

  FIG. 10 is a schematic cross-sectional view of a digital single-lens reflex camera CAM (optical apparatus) provided with the zoom lens having the above configuration as a photographing lens 1. In the digital single-lens reflex camera CAM shown in FIG. 10, light from an object (subject) (not shown) is collected by the photographing lens 1 and focused on the focusing screen 4 through the quick return mirror 3. The light imaged on the focusing screen 4 is reflected a plurality of times in the pentaprism 5 and guided to the eyepiece lens 6. Thus, the photographer can observe the object (subject) image as an erect image through the eyepiece 6.

  Further, when a release button (not shown) is pressed by the photographer, the quick return mirror 3 is retracted out of the optical path, and light of an object (subject) (not shown) condensed by the photographing lens 1 is captured on the image sensor 7. Form an image. Thereby, the light from the object (subject) is captured by the image sensor 7 and recorded as an object (subject) image in a memory (not shown). In this way, the photographer can photograph an object (subject) with the camera CAM. Note that the camera CAM illustrated in FIG. 10 may hold the photographic lens 1 in a detachable manner, or may be formed integrally with the photographic lens 1. In addition, the zoom lens of the present embodiment can ensure a sufficiently long back focus, and the camera CAM may be a so-called single-lens reflex camera or a camera without a quick return mirror or the like.

  Hereinafter, each example according to the present embodiment will be described with reference to the drawings. Tables 1 to 3 are shown below, but these are tables of specifications in the first to third examples.

  In [Overall specifications], f represents the focal length of the entire lens system, FNO represents the F number, 2ω represents the half field angle, Y represents the image height, TL represents the total length of the lens system, and Bf represents the back focus.

  In [Lens data], the surface number is the order of the lens surfaces from the object side along the direction in which the light beam travels, r is the radius of curvature of each lens surface, and d is the next optical surface (or image from each optical surface). The distance between the surfaces, which is the distance on the optical axis to the surface), νd is the Abbe number for the d-line, and nd is the refractive index for the d-line (wavelength 587.6 nm). When the lens surface is aspherical, an asterisk is attached to the surface number, and the paraxial radius of curvature is indicated in the column of the radius of curvature r. Note that the curvature radii “0.0000” and “∞” indicate a plane or an opening. Further, the description of the refractive index “1.00000” of air is omitted.

In [Aspherical Data], the shape of the aspherical surface shown in [Lens Data] is shown by the following equation (a). That is, y is the height in the direction perpendicular to the optical axis, and S (y) is the distance (sag amount) along the optical axis from the tangent plane at the apex of the aspheric surface to the position on the aspheric surface at height y. When the radius of curvature (paraxial radius of curvature) of the reference spherical surface is r, the conic coefficient is K, and the n-th aspherical coefficient is An, the following equation (a) is given. In each embodiment, the secondary aspheric coefficient A2 is 0, and the description thereof is omitted. Further, En represents × 10 ^n. For example, 1.234E-05 = 1.234 × 10 ⁻⁵ .

S (y) = (y ² / r) / {1+ (1−K · y ² / r ² ) ^1/2 } + A 3 × | y ³ |
^{+ A4 × y 4 + A6 ×} y 6 + A8 × y 8 + A10 × y 10 + A12 × y 12 + A14 × y 14 ... (a)

  In [Variable surface distance data], f is the focal length of the entire lens system, β is the imaging magnification between the object and the image, Di (where i is an integer) is the variable surface distance of the i-th surface, and Bf Indicates back focus. 1-POS is focused at infinity in the wide-angle end state, 2-POS is focused at infinity in the first intermediate focal length state, and 3-POS is focused at infinity in the second intermediate focal length state. 4-POS is in focus at infinity in the telephoto end state, 5-POS is in focus at β = −0.03333 in the wide-angle end state, and 6-POS is in the first intermediate focal length state. When focusing at β = −0.03333, 7-POS is when focusing at β = −0.03333 in the second intermediate focal length state, and 8-POS is when β = −0. At the time of focusing at 03333, 9-POS is for short distance focusing in the wide-angle end state, 10-POS is for short distance focusing in the first intermediate focal length state, and 11-POS is the second intermediate focal length. 12-POS is the telephoto end when focusing at close range Indicating when short distance focusing in state.

  In [Lens Group Data], the initial surface and focal length of each group are shown.

  In [Conditional Expression Corresponding Value], values corresponding to the conditional expressions (1) to (6) are shown.

  In the table, “mm” is generally used as the unit of focal length f, radius of curvature r, surface interval d, and other lengths. However, since the optical system can obtain the same optical performance even when proportionally enlarged or proportionally reduced, the unit is not limited to “mm”, and other appropriate units can be used.

  The description of the above table is the same in other examples, and the description thereof is omitted.

(First embodiment)
A first embodiment will be described with reference to FIGS. 1 to 3 and Table 1. FIG. FIG. 1 shows a lens configuration diagram and zoom locus of the first embodiment. As shown in FIG. 1, the zoom lens according to the first example includes a first lens group G1 having a positive refractive power and a second lens having a negative refractive power, which are arranged in order from the object side along the optical axis. It has a lens group G2, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power.

  The first lens group G1 includes, in order from the object side, a cemented positive lens including a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. Have.

  The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having an aspheric surface with a convex surface facing the object side, a biconcave lens L22, a biconvex lens L23, and a negative meniscus lens having a concave surface facing the object side. And a negative positive meniscus lens L25 having a concave surface facing the object side. The negative meniscus lens L21 is a so-called composite aspheric lens having both a portion made of a resin material having an aspheric surface and a portion made of a glass material.

  The third lens group G3 includes a biconvex lens L31, a positive meniscus lens L32 having a convex surface facing the object side, a negative meniscus lens L33 having a convex surface facing the object side, and a convex surface facing the object side. And a positive cemented lens composed of a positive meniscus lens L34.

  The fourth lens group G4 includes, in order from the object side, a lens group GA having a negative refractive power for performing camera shake correction by moving the lens group so as to have a component substantially orthogonal to the optical axis, and a negative refractive power. A lens group GB. The lens group GA includes a cemented negative lens that is arranged in order from the object side and includes a biconcave lens L41 and an aspheric positive lens L42 having an aspheric surface on the image side and a convex surface facing the object side. The lens group GB includes a negative meniscus lens L43 having a concave surface facing the object side.

  The fifth lens group G5 is composed of an aspherical biconvex lens L51 having an aspheric surface on the image side and a cemented positive lens that is composed of a biconvex lens L52 and a negative meniscus lens L53 having a concave surface on the object side. And a negative meniscus lens L54 having a concave surface facing the object side.

  In the zoom lens according to the present embodiment having such a configuration, when zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group increases, and the second lens group G2 And the third lens group G3 are decreased, the distance between the third lens group G3 and the fourth lens group G4 is increased, and the distance between the fourth lens group G4 and the fifth lens group G5 is decreased. At this time, the third lens group G3 and the fifth lens group G5 move together.

  In the zoom lens according to the present embodiment, focusing on an object at a short distance from infinity is performed by extending the object toward the object in the second lens group G2.

  The aperture stop S is disposed between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 upon zooming from the wide-angle end state to the telephoto end state.

  Table 1 below shows values of various specifications of the zoom lens according to the first example. In addition, the surface numbers 1-35 in Table 1 respond | correspond to the surfaces 1-35 shown in FIG.

(Table 1)
[Overall specifications]
f = 29.1-292
FNO = 3.6 ~ 5.9
ω = 37.96 ° 〜4.11 °
Y = 21.6
TL = 163.77-239.01
Bf = 38.30 ~ 79.07
[Lens data]
Surface number r d νd nd
1 151.1527 1.8000 32.35 1.850260
2 68.0198 10.0255 82.52 1.497820
3 -538.6972 0.1000
4 66.3072 6.3291 63.38 1.618000
5 472.1276 D5
* 6 107.6136 0.2000 38.09 1.553890
7 107.6136 1.0000 52.29 1.755000
8 18.4339 6.5000
9 -48.3041 1.0000 40.77 1.883000
10 75.1044 0.1000
11 35.4941 6.0000 25.43 1.805180
12 -25.1321 1.0000 46.63 1.816000
13 -39.5271 1.0000
14 -25.8306 1.0000 46.63 1.816000
15 -6376.7789 D15
16 Aperture stop S 1.0000
17 1255.1135 3.5000 69.89 1.518600
18 -42.5806 0.1000
19 26.2857 4.0000 82.56 1.497820
20 245.0143 0.1000
21 27.9820 1.0000 25.43 1.805180
22 14.7422 6.5000 58.89 1.518230
23 190.7576 D23
24 -90.8993 1.0000 49.61 1.772500
25 15.3080 4.5000 32.35 1.850 260
* 26 47.3128 4.0000
27 -24.6747 1.0000 42.72 1.834810
28 -50.9926 D28
29 47.8109 8.0000 69.89 1.518600
* 30 -24.7604 4.8012
31 43.6539 8.0000 52.32 1.517420
32 -25.7562 2.0000 40.77 1.883000
33 -49.5366 2.0000
34 -28.1887 1.0000 46.63 1.816000
35 -184.7070 Bf
[Aspherical data]
6th surface κ = 15.3921, A3 = -0.59282E-05, A4 = 1.30620E-06, A6 = 9.36650E-09,
A8 = -1.11260E-10, A10 = 4.97080E-13, A12 = -0.56752E-15, A14 = 0.00000
26th surface κ = -25.8788, A3 = 0.000000, A4 = 3.09780E-05, A6 = -1.24430E-07,
A8 = 3.167720E-10, A10 = 0.00000, A12 = 0.00000, A14 = 0.00000
30th surface κ = 0.0568, A3 = 0.35585E-06, A4 = 4.96950E-09, A6 = 5.91140E-09,
A8 = -4.14490E-11, A10 = 1.10780E-13, A12 = 0.00000, A14 = 0.00000
[Variable surface interval data]
1-POS 2-POS 3-POS 4-POS
f, β 29.09101 48.2400 100.6506 291.819
D0 0.0000 0.0000 0.0000 0.0000
D5 2.12367 17.46296 38.43018 62.16137
D15 26.06867 19.06022 11.97558 0.49737
D23 2.32242 3.99110 5.71830 6.85273
D28 6.40577 4.73716 3.00987 1.87544
Bf 38.29617 48.53884 64.87857 79.06793

5-POS 6-POS 7-POS 8-POS
β -0.03333 -0.03333 -0.03333 -0.03333
D0 821.2069 1353.4997 2798.6977 6780.5062
D5 1.47269 16.83833 37.68497 58.30009
D15 26.71965 19.68485 12.72079 4.35865
D23 2.32242 3.99110 5.71830 6.85273
D28 6.40577 4.73716 3.00987 1.87544
Bf 38.29617 48.53884 64.87857 79.06794

9-POS 10-POS 11-POS 12-POS
β -0.07534 -0.11871 -0.21005 -0.31900
D0 336.2274 317.6538 287.4316 260.5686
D5 0.66800 15.29562 34.15968 48.72149
D15 27.52434 21.22756 16.24608 13.93725
D23 2.32242 3.99110 5.71830 6.85273
D28 6.40577 4.73716 3.00987 1.87544
Bf 38.29617 48.53885 64.87856 79.06793
[Lens group data]
Group number Group first surface Group focal length G1 1 106.56812
G2 6 -17.08486
G3 16 27.20141
G4 24 -24.83040
G5 29 33.33177
[Conditional expression values]
Conditional expression (1) f5 / ft = 0.114
Conditional expression (2) (− f2) / (− f4) = 0.
Conditional expression (3) (-f4) /ft=0.085
Conditional expression (4) (-fA) /ft=0.159
Conditional expression (5) f5 / (-f4) = 1.342
Conditional expression (6) f5 / fw = 1.145

  From the table of specifications shown in Table 1, it can be seen that the zoom lens according to Example 1 satisfies all the conditional expressions (1) to (6).

  FIGS. 2A and 2B are diagrams showing various aberrations at the time of focusing on infinity in the wide-angle end state of the zoom lens according to Example 1, and image blur correction (shift amount of the lens group GA which is an image stabilizing group). = 0.27) is a transverse aberration diagram. FIGS. 3A and 3B are diagrams showing various aberrations at the time of focusing on infinity in the telephoto end state of the zoom lens according to the first example and image blur correction (shift amount of the lens group GA which is an image stabilizing group). = 0.50) is a lateral aberration diagram when.

  In each aberration diagram, FNO represents an F number, and Y represents an image height (unit: mm). The spherical aberration diagram shows the F-number value corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum image height, and the coma diagram shows the value of each image height. Further, d indicates various aberrations with respect to the d-line (wavelength 587.6 nm), g indicates various aberrations with respect to the g-line (wavelength 435.8 nm), and those not described indicate various aberrations with respect to the d-line. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. The explanation of the above aberration diagrams is the same in the other examples, and the explanation is omitted.

  As is apparent from the respective aberration diagrams, in the first example, it is understood that various aberrations are well corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent imaging performance is obtained.

(Second embodiment)
A second embodiment will be described with reference to FIGS. 4 to 6 and Table 2. FIG. FIG. 4 shows a lens configuration diagram and zoom locus of the second embodiment. As shown in FIG. 4, the zoom lens according to the second example includes a first lens group G1 having a positive refractive power and a second lens having a negative refractive power, which are arranged in order from the object side along the optical axis. It has a lens group G2, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power.

  The first lens group G1 includes, in order from the object side, a cemented positive lens including a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. And a positive meniscus lens L13.

  The second lens group G2 includes an aspheric negative meniscus lens L21 having a convex surface facing the object side and an aspheric surface on the object side, a biconcave lens L22, a biconvex lens L23, and an object side. And a plano-concave lens L24 having a concave surface.

  The third lens group G3 includes, in order from the object side, a biconvex lens L31, a cemented positive lens including the biconvex lens L32 and a negative meniscus lens L33 having a concave surface facing the object side, and a negative lens having a convex surface facing the object side. It has a cemented positive lens composed of a meniscus lens L34 and a biconvex lens L35.

  The fourth lens group G4 has a negative refractive power, a lens group GA having negative refractive power, which is arranged in order from the object side, and performs camera shake correction by moving so as to have a component substantially orthogonal to the optical axis. And a lens group GB. The lens group GA has a cemented negative lens composed of a biconcave lens L41 and a positive meniscus lens having a convex surface facing the object side, which are arranged in order from the object side. The lens group GB includes a negative meniscus lens L43 having a concave surface facing the image side. The negative meniscus lens L43 is a so-called composite aspheric lens having both a portion made of a resin material having an aspheric surface and a portion made of a glass material.

  The fifth lens group G5 is composed of an aspherical biconvex lens L51 having an aspheric surface on the image side and a cemented positive lens that is composed of a biconvex lens L52 and a negative meniscus lens L53 having a concave surface on the object side. And a negative meniscus lens L54 having a concave surface facing the object side.

  In the zoom lens according to the present embodiment having such a configuration, when zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group increases, and the second lens group G2 And the third lens group G3 are decreased, the distance between the third lens group G3 and the fourth lens group G4 is increased, and the distance between the fourth lens group G4 and the fifth lens group G5 is decreased. At this time, the third lens group G3 and the fifth lens group G5 move together.

  In the zoom lens according to the present embodiment, focusing on an object at a short distance from infinity is performed by extending the object toward the object in the second lens group G2.

  The aperture stop S is disposed between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 upon zooming from the wide-angle end state to the telephoto end state.

  Table 2 below shows values of various specifications of the zoom lens according to the second example. The surface numbers 1 to 35 in Table 2 correspond to the surfaces 1 to 35 shown in FIG.

(Table 2)
[Overall specifications]
f = 28.8-292
FNO = 3.6 ~ 5.9
ω = 38.31 ° ~ 4.09 °
Y = 21.6
TL = 154.81-230.36
Bf = 38.26-78.33
[Lens data]
Surface number r d νd nd
1 110.7015 2.0000 32.34 1.850 260
2 61.1227 9.3000 82.56 1.497820
3 831.5286 0.1000
4 71.2987 7.1000 67.87 1.593189
5 1005.3945 D5
* 6 127.2929 1.3500 46.82 1.766840
7 17.2677 6.0759
8 -54.3521 1.0000 46.58 1.804000
9 55.9968 0.5000
10 32.6904 4.4000 22.79 1.808090
11 -48.8263 0.9415
12 -28.5862 1.0000 46.58 1.804000
13 ∞ D13
14 Aperture stop S 0.5000
15 50.7881 3.4000 54.66 1.729160
16 -102.1535 0.1000
17 41.2071 4.7000 82.56 1.497820
18 -39.6235 1.0000 32.35 1.850 260
19 -152.2422 0.1000
20 26.8457 1.4000 32.35 1.850 260
21 14.8725 5.6000 69.89 1.518600
22 -558.6358 D22
23 -74.8002 1.0000 49.61 1.772500
24 15.4519 3.1425 32.34 1.850 260
25 54.7491 2.6536
* 26 1622.7936 0.3000 38.09 1.553890
27 1622.7936 1.2000 54.66 1.729160
28 57.4462 D28
29 113.9864 5.6000 61.18 1.589130
* 30 -33.2537 0.1000
31 84.5332 6.7000 58.89 1.518230
32 -20.6076 1.4000 40.76 1.883000
33 -31.0038 2.2000
34 -18.9228 1.2000 40.77 1.883000
35 -35.7750 Bf
[Aspherical data]
6th surface κ = 6.0978, A3 = 0.00000, A4 = 1.20280E-06, A6 = 1.30920E-08,
A8 = -1.37530E-10, A10 = 5.64160E-13, A12 = -0.74954E-15, A14 = 0.00000
26th surface κ = 100.0000, A3 = 0.00000, A4 = 8.03660E-06, A6 = -9.88790E-08,
A8 = 1.39310E-09, A10 = -6.555480E-12, A12 = 0.00000, A14 = 0.00000
30th surface κ = 1.9575, A3 = 0.00000, A4 = -3.55160E-06, A6 = -5.40150E-08,
A8 = 1.61410E-10, A10 = -6.70370E-13, A12 = -0.18148E-15, A14 = -0.10467E-17
[Variable surface interval data]
1-POS 2-POS 3-POS 4-POS
F, β 28.80002 50.00000 100.00005 292.00014
D0 0.0000 0.0000 0.0000 0.0000
D5 2.33995 17.99752 37.84134 64.87735
D13 28.56163 19.59632 12.37520 1.50817
D22 2.90075 4.91772 7.01855 8.31016
D28 6.68309 4.66612 2.56529 1.27369
Bf 38.26493 50.16229 66.37665 78.33071

5-POS 6-POS 7-POS 8-POS
F, β -0.03333 -0.03333 -0.03333 -0.03333
D0 813.3836 1407.7910 2802.5923 7194.7515
D5 1.70387 17.42468 37.21607 62.05719
D13 29.19771 20.16916 13.00047 4.32833
D22 2.90075 4.91772 7.01855 8.31016
D28 6.68309 4.66612 2.56529 1.27369
Bf 38.26493 50.16228 66.37664 78.33067

9-POS 10-POS 11-POS 12-POS
β -0.07303 -0.12069 -0.21096 -0.32000
D0 345.1860 326.5964 297.7593 274.0088
D5 0.95928 15.97061 34.15946 52.81222
D13 29.94230 21.62323 16.05708 13.57330
D22 2.90075 4.91772 7.01855 8.31016
D28 6.68309 4.66612 2.56529 1.27369
Bf 38.26493 50.16228 66.37664 78.33067
[Lens group data]
Group number Group first surface Group focal length G1 1 111.46551
G2 6 -16.92695
G3 16 25.25179
G4 23 -29.10021
G5 29 48.25475
[Conditional expression values]
Conditional expression (1) f5 / ft = 0.165
Conditional expression (2) (− f2) / (− f4) = 0.582
Conditional expression (3) (-f4) /ft=0.100
Conditional expression (4) (-fA) /ft=0.163
Conditional expression (5) f5 / (− f4) = 1.658
Conditional expression (6) f5 / fw = 1.676

  From the table of specifications shown in Table 2, it can be seen that the zoom lens according to Example 2 satisfies all the conditional expressions (1) to (6).

  FIGS. 5A and 5B are diagrams showing various aberrations at the time of focusing on infinity in the wide-angle end state of the zoom lens according to Example 2, and image blur correction (shift amount of the lens group GA which is the image stabilizing group). = 0.27) is a transverse aberration diagram. FIGS. 6A and 6B are diagrams showing various aberrations at the time of focusing on infinity in the telephoto end state of the zoom lens according to Example 2, and image blur correction (shift amount of the lens group GA which is the image stabilizing group). = 0.50) is a lateral aberration diagram when.

  As is apparent from the respective aberration diagrams, in the second example, it is understood that various aberrations are favorably corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent imaging performance is obtained.

(Third embodiment)
A third embodiment will be described with reference to FIGS. FIG. 7 shows a lens configuration diagram and zoom locus of the third embodiment. As shown in FIG. 7, the zoom lens according to the third example includes a first lens group G1 having a positive refractive power and a second lens having a negative refractive power, which are arranged in order from the object side along the optical axis. It has a lens group G2, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power.

  The first lens group G1 includes, in order from the object side, a cemented positive lens including a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. And a positive meniscus lens L13.

  The second lens group G2 includes an aspheric negative meniscus lens L21 having a convex surface facing the object side and an aspheric surface on the object side, a biconcave lens L22, a biconvex lens L23, and an object side. And a plano-concave lens L24 having a concave surface.

  The third lens group G3 includes, in order from the object side, a biconvex lens L31, a cemented positive lens including the biconvex lens L32 and a negative meniscus lens L33 having a concave surface facing the object side, and a negative lens having a convex surface facing the object side. It has a cemented positive lens composed of a meniscus lens L34 and a biconvex lens L35.

  The fourth lens group G4 has a negative refractive power, a lens group GA having negative refractive power, which is arranged in order from the object side, and performs camera shake correction by moving so as to have a component substantially orthogonal to the optical axis. And a lens group GB. The lens group GA has a cemented negative lens composed of a biconcave lens L41 and a positive meniscus lens L42 having a convex surface facing the object side, which are arranged in order from the object side. The lens group GB includes a negative meniscus lens L43 having a concave surface facing the image side. The negative meniscus lens L43 is a so-called composite aspheric lens having both a portion made of a resin material having an aspheric surface and a portion made of a glass material.

  The fifth lens group G5 is composed of an aspherical biconvex lens L51 having an aspheric surface on the image side and a cemented positive lens that is composed of a biconvex lens L52 and a negative meniscus lens L53 having a concave surface on the object side. And a negative meniscus lens L54 having a concave surface facing the object side.

  In the zoom lens according to the present embodiment having such a configuration, when zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group increases, and the second lens group G2 And the third lens group G3 are decreased, the distance between the third lens group G3 and the fourth lens group G4 is increased, and the distance between the fourth lens group G4 and the fifth lens group G5 is decreased. At this time, the third lens group G3 and the fifth lens group G5 move together.

  In the zoom lens according to the present embodiment, focusing on an object at a short distance from infinity is performed by extending the object toward the object in the second lens group G2.

  The aperture stop S is disposed between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 upon zooming from the wide-angle end state to the telephoto end state.

  Table 3 below shows values of various specifications of the zoom lens according to the third example. The surface numbers 1 to 34 in Table 3 correspond to the surfaces 1 to 34 shown in FIG.

(Table 3)
[Overall specifications]
f = 28.8-292
FNO = 3.6 ~ 5.9
ω = 38.39 ° ~ 4.07 °
Y = 21.6
TL = 157.37 ~ 230.34
Bf = 38.02 ～ 78.21
[Lens data]
Surface number r d νd nd
1 117.2951 2.0000 32.34 1.850260
2 63.4102 9.6000 82.56 1.497820
3 1973.1119 0.1000
4 70.5086 7.0000 67.87 1.593189
5 816.0257 D5
* 6 166.4533 1.3500 46.82 1.766840
7 18.7190 6.1000
8 -58.8089 1.0000 46.58 1.804000
9 55.5875 0.5000
10 33.5848 4.7000 22.79 1.808090
11 -54.2907 1.1000
12 -29.9194 1.0000 46.58 1.804000
13 ∞ D13
14 Aperture stop S 0.5000
15 42.4257 4.0000 64.12 1.516800
16 -52.8020 0.1000
17 26.4500 5.5000 82.56 1.497820
18 -42.7941 1.0000 32.35 1.850260
19 -465.6905 0.1000
20 31.4200 1.5000 42.72 1.834810
21 13.5952 6.0000 69.89 1.518600
22 -255.9214 D22
23 -94.4144 1.0000 49.61 1.772500
24 15.3153 2.9928 32.34 1.850 260
25 47.6604 4.5449
* 26 -23.6399 0.2000 38.09 1.553890
27 -23.6399 1.2000 54.66 1.729160
28 -58.9473 D28
29 112.3256 5.0000 61.18 1.589130
* 30 -31.9459 0.1000
31 191.3590 6.6657 82.56 1.497820
32 -22.5309 3.1289
33 -22.6718 1.3000 46.63 1.816000
34 -99.6640 Bf
[Aspherical data]
6th surface κ = 1.0000, A3 = 0.00000, A4 = 7.00430E-07, A6 = 9.58940E-09,
A8 = -9.46680E-11, A10 = 4.00920E-13, A12 = -0.66807E-15, A14 = 0.31353E-18
26th surface κ = 1.4228, A3 = 0.00000, A4 = 1.68800E-05, A6 = 5.21330E-08,
A8 = 1.71590E-10, A10 = 0.00000, A12 = 0.00000, A14 = 0.00000
30th surface κ = 1.000, A3 = 0.000, A4 = 1.80100E-05, A6 = 3.10700E-08,
A8 = -1.34120E-10, A10 = 9.05530E-13, A12 = 0.85085E-15, A14 = -0.11437E-16
[Variable surface interval data]
1-POS 2-POS 3-POS 4-POS
F, β 28.80000 50.00000 100.00000 291.99996
D0 0.0000 0.0000 0.0000 0.0000
D5 2.29069 15.44974 36.89931 63.76637
D13 30.69148 20.78037 13.67932 1.99142
D22 1.45891 3.45176 5.01843 5.79638
D28 5.62778 3.63493 2.06826 1.29031
Bf 38.01698 50.94008 66.10148 78.20934

5-POS 6-POS 7-POS 8-POS
F, β -0.03333 -0.03333 -0.03333 -0.03333
D0 811.3735 1412.4237 2798.6550 6931.8537
D5 1.59706 14.86615 36.21775 60.20067
D13 31.38511 21.36396 14.36088 5.55712
D22 1.45891 3.45176 5.01843 5.79638
D28 5.62778 3.63493 2.06826 1.29031
Bf 38.01698 50.94008 66.10149 78.20935

9-POS 10-POS 11-POS 12-POS
β -0.07317 -0.12008 -0.21059 -0.31600
D0 342.6319 326.4609 296.9509 268.8877
D5 0.78400 13.36202 32.92279 50.47276
D13 32.19817 22.86809 17.65584 15.28503
D22 1.45891 3.45176 5.01843 5.79638
D28 5.62778 3.63493 2.06826 1.29031
Bf 38.01698 50.94008 66.10150 78.20938
[Lens group data]
Group number Group first surface Group focal length G1 1 110.40923
G2 6 -17.47291
G3 16 25.33835
G4 23 -24.38340
G5 29 40.32144
[Conditional expression values]
Conditional expression (1) f5 / ft = 0.138
Conditional expression (2) (-f2) / (-f4) = 0.717
Conditional expression (3) (− f4) /ft=0.0835
Conditional expression (4) (-fA) /ft=0.162
Conditional expression (5) f5 / (− f4) = 1.654
Conditional expression (6) f5 / fw = 1.400

  From the table of specifications shown in Table 3, it can be seen that the zoom lens according to Example 3 satisfies all the conditional expressions (1) to (6).

  FIGS. 8A and 8B are graphs showing various aberrations at the time of focusing on infinity in the wide-angle end state of the zoom lens according to Example 3, and image blur correction (the shift amount of the lens group GA which is an image stabilizing group). = 0.27) is a transverse aberration diagram. FIGS. 9A and 9B are diagrams showing various aberrations at the time of focusing on infinity in the telephoto end state of the zoom lens according to Example 3, and image blur correction (shift amount of the lens group GA which is an image stabilizing group). = 0.50) is a lateral aberration diagram when.

  As is apparent from the respective aberration diagrams, in the third example, it is understood that various aberrations are well corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent imaging performance is obtained.

  In the above-described embodiment, the following description can be appropriately adopted as long as the optical performance is not impaired.

  In the above embodiment, the five-group configuration is shown, but the present invention can also be applied to other group configurations such as the sixth group and the seventh group. Further, a configuration in which a lens or a lens group is added to the most object side, or a configuration in which a lens or a lens group is added to the most image side may be used. The lens group refers to a portion having at least one lens separated by an air interval that changes during zooming.

  In addition, a single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to be a focusing lens group that performs focusing from an object at infinity to a near object. The focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (such as an ultrasonic motor). In particular, it is preferable that at least a part of the second lens group G2 is a focusing lens group.

  In addition, the lens group or the partial lens group is moved so as to have a component in a direction perpendicular to the optical axis, or is rotated (swayed) in the in-plane direction including the optical axis to reduce image blur caused by camera shake. A vibration-proof lens group to be corrected may be used. In particular, it is preferable that at least a part of the fourth lens group G4 is an anti-vibration lens group. The movement may be rotational movement (swing) with a certain point on the optical axis as the rotation center.

  Further, the lens surface may be formed as a spherical surface, a flat surface, or an aspheric surface. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment are facilitated, and optical performance deterioration due to errors in processing and assembly adjustment can be prevented. In addition, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. If the lens is aspherical, the aspherical surface is an aspherical surface formed by grinding, a glass mold aspherical surface formed of glass with an aspherical shape, or a composite aspherical surface formed of resin on the glass surface with an aspherical shape. Any aspherical surface may be used. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

  The aperture stop S is preferably arranged in the vicinity of the third lens group G3 or the fourth lens group G4. However, the role of the aperture stop may be substituted by a lens frame without providing a member as an aperture stop. . In particular, the aperture stop S is more preferably on the object side of the third lens group G3.

  Each lens surface may be provided with an antireflection film having high transmittance in a wide wavelength region in order to reduce flare and ghost and achieve high optical performance with high contrast.

  The zoom lens (variable magnification optical system) of the present embodiment has a magnification ratio of 5 to 18 times, more preferably 8 to 12 times.

  In the zoom lens (variable magnification optical system) of the present embodiment, it is preferable that the first lens group G1 has two positive lenses and one negative lens. In the first lens group G1, it is preferable to dispose the lenses in order of negative / positive from the object side.

  In the zoom lens (variable magnification optical system) of the present embodiment, it is preferable that the second lens group G2 has one positive lens and three negative lenses. In the second lens group G2, it is preferable that lens components are arranged in order of negative, negative, positive and negative in order from the object side with an air gap interposed therebetween.

  In the zoom lens (variable magnification optical system) of the present embodiment, it is preferable that the third lens group G3 has three positive lenses and one negative lens. In the third lens group G3, it is preferable that lens components are arranged in order of positive and positive in order from the object side with an air gap interposed therebetween.

  In the zoom lens (variable magnification optical system) of the present embodiment, it is preferable that the fourth lens group G4 has one positive lens and two negative lenses. In the fourth lens group G4, it is preferable to dispose lens components in the order of negative and negative in order from the object side with an air gap interposed therebetween.

  In the zoom lens (variable magnification optical system) of the present embodiment, it is preferable that the fifth lens group G5 has two positive lenses and one negative lens. In the fifth lens group G5, it is preferable that lens components are arranged in order of positive and negative in order from the object side with an air gap interposed therebetween.

  In addition, in order to make this invention intelligible, although demonstrated with the component requirement of embodiment, it cannot be overemphasized that this invention is not limited to this.

It is a figure which shows the structure of a lens system and zoom locus | trajectory based on 1st Example. FIG. 7A is a diagram illustrating various aberrations when the zoom lens according to Example 1 is in focus at infinity in the wide-angle end state, and FIG. 9B is a lateral aberration diagram when image blur correction is performed. (A) is a diagram of various aberrations when focusing on infinity in the telephoto end state of the zoom lens according to Example 1, and (b) is a lateral aberration diagram when image blur correction is performed. It is a figure which shows the structure of a lens system and zoom locus | trajectory based on 2nd Example. (A) is a diagram of various aberrations when focusing on infinity in the wide-angle end state of the zoom lens according to Example 2, and (b) is a lateral aberration diagram when image blur correction is performed. (A) is the aberration diagram at the time of infinity focusing in the telephoto end state of the zoom lens according to Example 2, and (b) is a lateral aberration diagram when image blur correction is performed. It is a figure which shows the structure of a lens system and zoom locus | trajectory based on 3rd Example. FIG. 6A is a diagram illustrating various aberrations when the zoom lens according to Example 3 is in focus at infinity in the wide-angle end state, and FIG. 9B is a lateral aberration diagram when image blur correction is performed. (A) is a diagram of various aberrations when focusing on infinity in the telephoto end state of the zoom lens according to Example 3, and (b) is a lateral aberration diagram when image blur correction is performed. 1 is a schematic cross-sectional view of a digital single-lens reflex camera CAM (optical apparatus) including a zoom lens having the above configuration.

Explanation of symbols

G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group GA Lens group having negative refractive power GB Lens group positioned on the image side of the lens group GA G5 Fifth lens group S Aperture stop I Image plane CAM Digital SLR camera (optical equipment)

Claims (15)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a first lens group having a negative refractive power, arranged in order from the object side. 4 lens groups and a fifth lens group having positive refractive power,
Moving at least a part of the fourth lens group so as to have a component orthogonal to the optical axis;
When zooming from the wide-angle end state to the telephoto end state, the distance between the lens groups changes
When the focal length of the fifth lens group is f5, and the focal length in the telephoto end state when the entire lens system is in focus at infinity is ft, the following expression 0.01 <f5 / ft <0.30
A zoom lens that satisfies the following conditions. When the focal length of the second lens group is f2 and the focal length of the fourth lens group is f4, the following formula 0.577 <(− f2) / (− f4) <1.200
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition. When the focal length of the fourth lens group is f4 and the focal length is ft in the telephoto end state when the entire lens system is focused at infinity, the following expression 0.01 <(− f4) / ft <0.25
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.   The fourth lens group includes a lens group GA having a negative refractive power and a lens group GB which is disposed adjacent to the image side of the lens group GA and has a negative refractive power. The zoom lens according to any one of claims 1 to 3.   The zoom lens according to claim 4, wherein the lens group GB includes at least one aspheric surface. When the focal length of the lens group moving so as to have a component orthogonal to the optical axis is fA, and the focal length in the telephoto end state when the entire lens system is focused at infinity is ft, the following expression 0.05 <(-FA) / ft <0.40
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition. When the focal length of the fourth lens group is f4 and the focal length of the fifth lens group is f5, the following expression 1.10 <f5 / (− f4) <2.00
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition. When the focal length of the fifth lens group is f5 and the focal length at the wide-angle end state when the entire lens system is focused at infinity is fw, the following expression is satisfied: 0.11 <f5 / fw <3.20
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.   The zoom lens according to claim 1, wherein the fourth lens group includes a cemented lens.   During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, The distance between the third lens group and the fourth lens group is increased, and the distance between the fourth lens group and the fifth lens group is decreased. The described zoom lens.   The zoom lens according to any one of claims 1 to 10, wherein the third lens group and the fifth lens group move together when zooming from the wide-angle end state to the telephoto end state. . The third lens group has three lens groups having positive refractive power,
The zoom lens according to claim 1, wherein the three lens groups include at least two cemented lenses.   The zoom according to any one of claims 1 to 12, wherein focusing from an object at infinity to an object at a close distance is performed by moving at least a part of the second lens group in the optical axis direction. lens.   An optical apparatus comprising the zoom lens according to claim 1. A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a first lens group having a negative refractive power, arranged in order from the object side. A zoom lens zooming method having four lens groups and a fifth lens group having a positive refractive power,
Moving at least a part of the fourth lens group so as to have a component orthogonal to the optical axis;
When zooming from the wide-angle end state to the telephoto end state, the distance between the lens groups changes
When the focal length of the fifth lens group is f5, and the focal length in the telephoto end state when the entire lens system is in focus at infinity is ft, the following expression 0.01 <f5 / ft <0.30
A zoom lens zooming method characterized by satisfying the following conditions:

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