JP2010145759A - Zoom lens, optical apparatus with the zoom lens and method for producing the zoom lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens having high variable magnification and having excellent imaging performance, to provide an optical apparatus with the zoom lens, and to provide a method for producing the zoom lens. <P>SOLUTION: The zoom lens ZL mounted on a digital single-lens reflex camera 1 or the like comprises, in order from an object side: a first lens group G1 having positive dioptric power; a second lens group G2 having negative dioptric power; a third lens group G3 having positive dioptric power; and a fourth lens group G4 having positive dioptric power. Upon variable magnification from a wide angle end state to a telephoto end state, the first lens group G1 is fixed to an image face, and at least the second lens group G2 and fourth lens group G4 move in such a manner that intervals among the respective lens groups change. The fourth lens group G4 comprises the front part lens group G4F and the rear part lens group G4R arranged at the image side of the front part lens group G4F with air intervals, and the rear part lens group is moved to the optical axis direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a zoom lens, an optical apparatus including the zoom lens, and a method for manufacturing the zoom lens.

Conventionally, a positive / negative positive / positive four-group type zoom lens is known (for example, see Patent Document 1). The positive, negative, positive, and positive four-group type zoom lens includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power in order from the object side. It includes at least a fourth lens group having a positive refractive power, and is constituted by four lens groups. The fourth lens group includes at least two partial lens groups having positive refractive power. At the time of zooming from the wide-angle end state (the shortest focal length) to the telephoto end state (the longest focal length), at least the second lens group and the fourth lens group move. Further, in the field of digital still cameras and video cameras using a solid-state image sensor or the like today, an optical system with higher optical performance is required with the recent increase in the number of pixels of the light receiving element. In addition, for convenience in photographing, an optical system having a high zoom ratio, a small size, and excellent portability is also required.
JP-A-9-288236

  However, in a light receiving element with an increased number of pixels, the conventional optical system tends to increase in size when the optical performance is improved, and when the optical system increases in size, the entire camera increases in size, resulting in a loss of convenience during shooting. There was a problem.

  The present invention has been made in view of such problems, and provides a zoom lens having high optical performance and good convenience during photographing, an optical apparatus including the zoom lens, and a method for manufacturing the zoom lens. For the purpose.

  In order to solve the above problem, a zoom lens according to a first aspect of the invention includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. And a fourth lens group having a positive refractive power. When zooming from the wide-angle end state to the telephoto end state, the first lens group is fixed with respect to the image plane, the distance between the first lens group and the second lens group changes, and the second lens group At least the second lens group and the fourth lens group move so that the distance between the third lens group changes and the distance between the third lens group and the fourth lens group changes. A front partial lens group and a rear partial lens group disposed on the image side of the front partial lens group with an air gap therebetween, and the rear partial lens group is moved in the optical axis direction to be focused.

  In the zoom lens, it is preferable that at least one of the third lens group and the fourth lens group includes one positive single lens and one cemented lens.

  In this zoom lens, the lens surface on the object side of the single lens is convex on the object side, the lens surface on the object side of the cemented lens is convex on the object side, and the lens on the image side of the cemented lens. The surface is preferably concave on the image side.

  In this zoom lens, it is preferable that the rear lens group in the fourth lens group has a negative refractive power.

  In this zoom lens, the rear lens group in the fourth lens group is integrated with the front lens group in the optical axis direction in the infinite focus state when zooming from the wide-angle end state to the telephoto end state. It is preferable that it is comprised so that it may move to.

  In this zoom lens, the front lens group and the rear lens group in the fourth lens group move in the optical axis direction at different speeds when zooming from the wide-angle end state to the telephoto end state. Preferably, it is configured.

  In this zoom lens, it is preferable that the front lens group in the fourth lens group has a positive refractive power.

  In this zoom lens, it is preferable that all of the optical elements included in the first lens group have refractive power.

In this zoom lens, when the focal length of the third lens group is f3 and the focal length of the fourth lens group is f4, the following expression 0.1 <f3 / f4 <3.0
It is preferable to satisfy the following conditions.

  In addition, this zoom lens preferably has an aperture stop between the second lens group and the third lens group.

  This zoom lens preferably includes at least one aspheric lens in the third lens group.

Further, in this zoom lens, when the focal length of the fourth lens group is f4 and the focal length of the rear lens group is f4R, the following expression 0.1 <| f4R | / f4 <6.7
It is preferable to satisfy the following conditions.

Further, in this zoom lens, when the focal length of the front lens group is f4F and the focal length of the rear lens group is f4R, the following expression 0.1 <| f4F | / | f4R | <1.5
It is preferable to satisfy the following conditions.

  Further, in this zoom lens, 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 is increased, and the distance between the second lens group and the third lens group is increased. It is preferable that the distance between the third lens group and the fourth lens group is reduced.

  In the zoom lens, it is preferable that the third lens group is fixed with respect to the image plane when zooming from the wide-angle end state to the telephoto end state.

  In this zoom lens, it is preferable that at least a part of the third lens group moves so as to have a component in a direction substantially perpendicular to the optical axis.

  The zoom lens according to the second invention is, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a positive refractive power. And a fourth lens group. When zooming from the wide-angle end state to the telephoto end state, the first lens group is fixed with respect to the image plane, the distance between the first lens group and the second lens group changes, and the second lens group At least the second lens group and the fourth lens group move and are included in the first lens group so that the distance between the third lens group changes and the distance between the third lens group and the fourth lens group changes. All of the optical elements have a refractive power, and the lens group arranged closest to the image side includes a lens component whose position on the optical axis is fixed at the time of focusing and an optical axis at the time of focusing. Lens component moving in the direction.

  An optical apparatus according to the present invention includes any one of the above-described zoom lenses that forms an image of an object on a predetermined image plane.

  The zoom lens manufacturing method according to the present invention includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a positive refractive power. A zoom lens manufacturing method having a lens group and a fourth lens group having a positive refractive power, and when zooming from the wide-angle end state to the telephoto end state, the first lens group is placed on the image plane. On the other hand, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, and the distance between the third lens group and the fourth lens group changes. In order to change, at least the second lens group and the fourth lens group are arranged to move, and the fourth lens group is separated from the front partial lens group by an air space on the image side of the front partial lens group. The rear partial lens group is disposed, and the rear partial lens group is moved in the optical axis direction. To focus.

  When the zoom lens according to the present invention, the optical device including the zoom lens, and the method for manufacturing the zoom lens are configured as described above, high optical performance and convenience during photographing can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the zoom lens ZL includes, in order from the object side, a first lens group G1 having a positive refractive index, a second lens group G2 having a negative refractive index, and positive refraction. The third lens group G3 having power and the fourth lens group G4 having positive refractive power are configured. When zooming from the wide-angle end state (the shortest focal length state) to the telephoto end state (the longest focal length state), the first lens group G1 is fixed with respect to the image plane, and the first lens group G1 The distance between the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, and the distance between the third lens group G3 and the fourth lens group G4 decreases. At least the second lens group G2 and the fourth lens group G4 move. By adopting such a configuration, the zoom lens ZL can have high optical performance and convenience during photographing.

  Next, the function of each lens group will be described. The first lens group G1 has a function of converging the light flux. Further, when the focal length changes from the wide-angle end state to the telephoto end state, the first lens group G1 is always fixed with respect to the image plane. By fixing the first lens group G1 in this way, it is possible to minimize performance deterioration in the telephoto end state. Further, by fixing the first lens group G1, the zoom lens ZL does not change in length and increases in size, but becomes excellent in portability.

  The second lens group G2 has an effect of enlarging the image of the subject formed by the first lens group G1, and as it goes from the wide-angle end state to the telephoto end state, the first lens group G1 and the second lens group G2 The focal length is changed by increasing the magnification by increasing the interval.

  The third lens group G3 has a function of converging the light beam expanded by the second lens group G2, and in order to achieve high performance, it is desirable that the third lens group G3 is composed of a plurality of lens groups.

  The fourth lens group G4 has a function of further converging the luminous flux converged by the third lens group G3, and when changing the focal length, the interval between the third lens group G3 and the fourth lens group G4 is positively changed. By changing to, fluctuations in the image plane with respect to changes in focal length can be suppressed. At this time, the fourth lens group G4 includes a front partial lens group G4F and a rear partial lens group G4R arranged with an air gap on the image side of the front partial lens group G4F. The lens group G4R is moved in the optical axis direction for focusing, and the amount of movement due to focusing is minimized.

  Here, if focusing is performed by moving the entire fourth lens group G4 in the optical axis direction, it is necessary to increase the distance between the third lens group G3 and the fourth lens group G4, and the optical performance deteriorates. May lead to However, since the zoom lens ZL uses the rear lens group G4R as the focusing group, the distance between the third lens group G3 and the fourth lens group G4 is reduced and the third lens group G3 is focused. It is preferable because the distance between the groups can be increased.

  In addition, in order to improve the performance of the zoom lens ZL, it is desirable to configure the third lens group G3 or the fourth lens group G4 as follows. That is, at least one of the third lens group G3 and the fourth lens group G4 is arranged in order from the object side in order to satisfactorily correct the on-axis aberration generated in the third lens group G3 or the fourth lens group G4 alone. It is desirable to be composed of one positive single lens and one cemented lens. At this time, the lens surface on the object side of the single lens is convex on the object side, the lens surface on the object side of the cemented lens is convex on the object side, and the lens surface on the image side of the cemented lens is on the image side. It is desirable to have a concave shape. Further, an aperture stop S is provided between the second lens group G2 and the third lens group G3, and the aperture stop S is fixed to the image plane when zooming from the wide-angle end state to the telephoto end state. It is desirable to be configured as follows.

  In the zoom lens ZL, it is desirable that the rear lens group G4R in the fourth lens group G4 has a negative refractive power in order to minimize the short-range fluctuation of aberration due to focusing.

  In the zoom lens ZL, the rear lens group G4R in the fourth lens group G4 is integrated with the front lens group G4F in the infinite focus state when zooming from the wide-angle end state to the telephoto end state. It is desirable to be configured to move in the optical axis direction.

  In the zoom lens ZL, the front partial lens group G4F and the rear partial lens group G4R in the fourth lens group G4 have different speeds in the optical axis direction when zooming from the wide-angle end state to the telephoto end state. Desirably configured to move.

  In this zoom lens, it is desirable that the front lens group G4F in the fourth lens group G4 has a positive refractive power in order to minimize fluctuations in field curvature due to focusing.

  In addition, it is desirable that the zoom lens ZL does not include an optical path bending element (for example, a prism or the like) for bending the optical path, and all of the optical elements included in the first lens group G1 each have refractive power.

  Now, conditions for configuring such a zoom lens ZL will be described. First, it is desirable that the zoom lens ZL satisfies the following conditional expression (1) when the focal length of the third lens group G3 is f3 and the focal length of the fourth lens group G4 is f4.

0.1 <f3 / f4 <3.0 (1)

  Conditional expression (1) is a conditional expression for defining an appropriate range for the focal length ratio between the third lens group G3 and the fourth lens group G4. If the upper limit of conditional expression (1) is exceeded, the refractive power of the third lens group G3 becomes relatively weak, and the total lens length becomes large. In addition, the spherical aberration and the coma aberration generated in the third lens group G3 are insufficiently corrected, and the desired optical performance cannot be achieved. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 2.70. In order to further secure the effect of the present embodiment, it is more preferable to set the upper limit of conditional expression (1) to 2.30. Furthermore, in order to further secure the effect of the present embodiment, it is more preferable to set the upper limit value of conditional expression (1) to 2.00. On the other hand, if the lower limit of conditional expression (1) is not reached, the refractive power of the second lens group G2 becomes strong and the divergence action becomes strong in order to ensure the back focus in the wide-angle end state. As a result, the light beam incident on the third lens group G3 spreads and the spherical aberration generated by the third lens group G3 alone increases, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.25. In order to further secure the effect of the present embodiment, it is more preferable to set the lower limit of conditional expression (1) to 0.35. In order to further secure the effect of the present embodiment, it is more preferable to set the lower limit of conditional expression (1) to 0.45.

  The zoom lens ZL preferably includes at least one aspheric lens in the third lens group G3. Thus, by arranging an aspheric lens in the third lens group G3, coma aberration and curvature of field generated by the third lens group G3 alone can be favorably corrected.

  In the zoom lens ZL, it is preferable that the following conditional expression (2) is satisfied when the focal length of the fourth lens group G4 is f4 and the focal length of the rear lens group G4R is f4R.

0.1 <| f4R | / f4 <6.7 (2)

  Conditional expression (2) is a conditional expression for defining an appropriate range for the focal length ratio between the fourth lens group G4 and the rear partial lens group G4R. When the upper limit of conditional expression (2) is exceeded, the refractive power of the rear lens group G4R becomes weak, and spherical aberration and coma generated in the fourth lens group G4 alone cannot be corrected well. In addition, the amount of movement at the time of focusing becomes large, which is not preferable. In order to secure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (2) to 6.0. In order to further secure the effect of the present embodiment, it is more preferable to set the upper limit of conditional expression (2) to 5.0. Furthermore, in order to further secure the effect of the present embodiment, it is more preferable to set the upper limit value of conditional expression (2) to 4.0. On the other hand, if the lower limit value of conditional expression (2) is not reached, the refractive power of the rear lens group G4R will become strong, and the spherical aberration and coma generated by the fourth lens group G4 alone will be undercorrected. . In addition, aberration fluctuation due to focusing increases, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.2. In order to further secure the effect of the present embodiment, it is more preferable to set the lower limit of conditional expression (2) to 0.3. Furthermore, in order to further secure the effect of the present embodiment, it is more preferable to set the lower limit of conditional expression (2) to 0.5.

  In addition, it is desirable that the zoom lens ZL satisfies the following conditional expression (3) when the focal length of the front partial lens group G4F is f4F and the focal length of the rear partial lens group G4R is f4R.

0.1 <| f4F | / | f4R | <1.5 (3)

  Conditional expression (3) is a conditional expression for defining an appropriate range for the focal length ratio between the front partial lens group G4F and the rear partial lens group G4R. If the upper limit of conditional expression (3) is exceeded, the refractive power of the rear lens group G4R becomes relatively strong, and spherical aberration and coma aberration generated in the fourth lens group G4 alone cannot be corrected well. End up. In addition, aberration fluctuation due to focusing increases, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to 1.3. In order to further secure the effect of the present embodiment, it is more preferable to set the upper limit value of conditional expression (3) to 1.1. Furthermore, in order to further secure the effect of the present embodiment, it is more preferable to set the upper limit of conditional expression (3) to 0.9. On the other hand, if the lower limit value of conditional expression (3) is not reached, the refractive power of the rear lens group G4R becomes relatively weak, and the spherical aberration and coma generated by the fourth lens group G4 alone are undercorrected. turn into. In addition, the amount of movement at the time of focusing becomes large, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to 0.15. In order to further secure the effect of the present embodiment, it is more preferable to set the lower limit of conditional expression (3) to 0.20.

  Further, in order to simplify the configuration of the mechanical parts of the zoom lens ZL, the third lens group G3 may be fixed with respect to the image plane when zooming from the wide-angle end state to the telephoto end state. desirable.

  In addition, it is desirable that the zoom lens ZL moves so that at least a part of the third lens group G3 has a component in a direction substantially perpendicular to the optical axis in order to correct image blur caused by camera shake.

  The zoom lens ZL according to the second invention has, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power. The third lens group G3 and the fourth lens group G4 may be included. When zooming from the wide-angle end state to the telephoto end state, the first lens group G1 is fixed with respect to the image plane, the distance between the first lens group G1 and the second lens group G2 increases, At least the second lens group G2 and the fourth lens group G4 are arranged so that the distance between the lens group G2 and the third lens group G3 is reduced and the distance between the third lens group G3 and the fourth lens group G4 is reduced. Moving. All of the optical elements included in the first lens group G1 have refractive power, and the position of the fourth lens group G4 arranged on the most image side is fixed on the optical axis at the time of focusing. It is desirable to have a lens component that moves and a lens component that moves in the optical axis direction during focusing. By adopting such a configuration, the zoom lens ZL can obtain excellent imaging performance while having a high zoom ratio.

  FIG. 12 is a schematic cross-sectional view of a digital single lens reflex camera 1 (hereinafter simply referred to as a camera) as an optical apparatus including the zoom lens ZL described above. In this camera 1, light from an object (subject) (not shown) is collected by the taking lens 2 (zoom lens ZL) and imaged on the focusing screen 4 via 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 2 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 shoot an object (subject) with the camera 1. Note that the camera 1 shown in FIG. 12 may hold the zoom lens ZL in a removable manner, or may be formed integrally with the zoom lens ZL. The camera 1 may be a so-called single-lens reflex camera or a compact camera without a quick return mirror or the like.

  The contents described below can be appropriately adopted as long as the optical performance is not impaired.

  In addition, this zoom lens ZL includes a blur detection system that detects blur of the lens system and a driving unit in order to prevent a shooting failure due to image blur caused by camera shake or the like that is likely to occur in a high-magnification zoom lens. The image blur caused by the blur of the lens system detected by the blur detection system is obtained by decentering all or part of one of the lens groups constituting the lens system as a shift lens group. The image blur can be corrected by driving the shift lens group by the driving unit and shifting the image so as to correct the fluctuation of the surface position. As described above, the zoom lens ZL of the present embodiment can function as a so-called anti-vibration optical system. In particular, it is preferable that at least a part of the lens group (the third lens group G3 in the present embodiment) whose position relative to the image plane is fixed at the time of zooming is an anti-vibration lens group.

  In this embodiment, the lens system is composed of two movable groups. However, another lens group is added between the lens groups, or the lens system is adjacent to the image side or the object side of the lens system. It is also possible to add these lens groups.

  In the present embodiment, the zoom lens ZL having a four-group configuration is shown, but the above-described configuration conditions and the like can also be applied to other group configurations such as a five-group configuration. 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 indicates a portion having at least one lens separated by an air interval that changes at the time of zooming.

  Alternatively, a single lens group or 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 infinite distance to a short-distance object point. In this case, 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, the rear lens group G4R of the fourth lens group G4 is preferably 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.

  Further, the lens surface may be formed as a spherical surface, a flat surface, or an aspheric surface. It is preferable that the lens surface is a spherical surface or a flat surface because lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to errors in processing and assembly adjustment is prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is an aspheric surface, the aspheric surface is an aspheric surface by grinding, a glass mold aspheric surface made of glass with an aspheric shape, or a composite aspheric surface made of resin with an aspheric shape on the glass surface. 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 disposed in the vicinity of the third lens group G3, but the role of the aperture stop may be substituted by a lens frame without providing a member as an aperture stop.

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

  In the zoom lens ZL of the present embodiment, it is preferable that the first lens group G1 has one positive lens component and one negative lens component. In addition, in the first lens group G1, it is preferable to arrange the lens components in the order of negative and positive in order from the object side with an air gap interposed therebetween. Alternatively, the first lens group G1 preferably has two positive lens components and one negative lens component. In the first lens group G1, it is preferable to dispose the lens components in order of negative positive / positive in order from the object side.

  In the zoom lens ZL of the present embodiment, it is preferable that the second lens group G2 has one positive lens component and two negative lens components.

  In the zoom lens ZL of the present embodiment, it is preferable that the third lens group G3 has two positive lens components and one negative lens component.

  In the zoom lens ZL of the present embodiment, it is preferable that the fourth lens group G4 has two positive lens components and one negative lens component. In addition, the focusing group is preferably composed of one cemented lens.

  The zoom lens ZL according to the present embodiment is preferably about 10 to 30 mm in a state where the distance (back focus) from the image side surface of the lens component arranged closest to the image side to the image surface is the smallest. In the zoom lens ZL according to the present embodiment, the image height is preferably 5 to 12.5 mm, and more preferably 5 to 9.5 mm.

  In addition, in order to explain the present invention in an easy-to-understand manner, the configuration requirements of the embodiment have been described, but it goes without saying that the present invention is not limited to this.

  Hereinafter, an outline of a method for manufacturing the zoom lens ZL of the present embodiment will be described with reference to FIG. First, each lens is arranged and a lens group is prepared (step S100). Specifically, in this embodiment, for example, in order from the object side, a cemented positive lens CL11 formed by bonding a negative meniscus lens L11 having a convex surface toward the object side and a positive meniscus lens L12 having a concave surface toward the image side. A positive meniscus lens L13 having a convex surface facing the object side is arranged as the first lens group G1, and in order from the object side, a negative meniscus lens L21 having aspheric surfaces on both surfaces and a convex surface facing the object side, and both A cemented positive lens CL21 formed by bonding a concave lens L23 and a positive meniscus lens L24 having a concave surface facing the image side is disposed to form a second lens group G2, and in order from the object side, an aspheric surface is provided on the object side and the object side is provided. A positive meniscus lens L31 having a concave surface and a cemented negative lens CL31 formed by bonding a biconvex lens L32 and a biconcave lens L33 are arranged to form a third lens. In the group G3, in order from the object side, a biconvex lens L41 having an aspheric surface on the image side, and a cemented negative lens CL41 formed by bonding the biconvex lens L42 and the biconcave lens L43 are arranged. Let it be a lens group G4. A zoom lens is manufactured by arranging the lens groups thus prepared.

  At this time, when zooming from the wide-angle end state to the telephoto end state, the first lens group G1 is fixed with respect to the image plane, the distance between the first lens group G1 and the second lens group G2 changes, At least the second lens group G2 and the fourth lens group G4 so that the distance between the second lens group G2 and the third lens group G3 changes and the distance between the third lens group G3 and the fourth lens group G4 changes. Are arranged so as to move (step S200).

  Further, in the fourth lens group G4, a front partial lens group G4F and a rear partial lens group G4R arranged with an air gap on the image side of the front partial lens group G4F are arranged, and the rear partial lens group G4R is arranged. It moves so that it may focus on by moving to an optical axis direction (step S300).

  Hereinafter, each example of the present embodiment will be described with reference to the drawings. FIG. 1 is a diagram showing a state of movement of each lens group in a refractive power distribution of the zoom lens ZL according to the present embodiment and a change in focal length state from the wide-angle end state (W) to the telephoto end state (T). . 2, 4, 6, 8, and 10 are cross-sectional views illustrating the configuration of the zoom lens ZL (ZL1 to ZL5) according to each embodiment. As shown in these drawings, each of the zoom lenses ZL1 to ZL5 according to each example has a first lens group G1 having a positive refractive power and a second lens having a negative refractive power in order from the object side. The lens unit G2 includes a group G2, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and a filter group FL. The fourth lens group G4 includes a front partial lens group G4F and a rear partial lens group G4R disposed on the image side of the front partial lens group G4F with an air space therebetween. When the focal length state changes from the wide-angle end state to the telephoto end state (ie, zooming), the distance between the first lens group G1 and the second lens group G2 increases, and the second lens group G2 and the third lens group. The distance between the third lens group G3 and the fourth lens group G4 decreases, the first lens group G1 and the third lens group G3 are fixed with respect to the image plane, and the second lens group G2 and the fourth lens group G4 move to the object side. Here, the filter group FL includes a low-pass filter, an infrared cut filter, and the like. The image plane I is imaged on an imaging element (not shown) (for example, a film, a CCD, a CMOS, etc.).

  The aperture stop S is disposed closest to the object side of the third lens group G3, and is fixed with respect to the image plane when zooming from the wide-angle end state to the telephoto end state. Focusing from infinity to a short-distance object point is performed by moving the rear lens group G4R of the fourth lens group G4 in the object direction. Camera shake correction (anti-vibration) is performed by moving the entire third lens group G3 or the cemented negative lens CL31 so as to have a component in a direction substantially perpendicular to the optical axis.

In each embodiment, the height of the aspheric surface in the direction perpendicular to the optical axis is y, and the distance (sag amount) along the optical axis from the tangential plane of the apex of each aspheric surface to each aspheric surface at height y. Is S (y), r is the radius of curvature of the reference sphere (paraxial radius of curvature), κ is the conic constant, and An is the nth-order aspheric coefficient, and is expressed by the following equation (a). . In the following examples, “E−n” indicates “× 10 ⁻ⁿ ”.

S (y) = (y ² / r) / {1+ (1−κ × y ² / r ² ) ^1/2 }
^{+ A4 × y 4 + A6 ×} y 6 + A8 × y 8 + A10 × y 10 (a)

  In each embodiment, the secondary aspheric coefficient A2 is zero. In the table of each example, an aspherical surface is marked with * on the left side of the surface number.

[First embodiment]
FIG. 2 is a diagram illustrating a configuration of the zoom lens ZL1 according to the first example. In the zoom lens ZL1 of FIG. 2, the first lens group G1 is composed of, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a concave surface facing the image side. It is composed of a cemented positive lens CL11 and a positive meniscus lens L13 having a convex surface facing the object side. The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having aspheric surfaces on both sides and a convex surface facing the object side, a biconcave lens L22, and a positive meniscus lens L23 having a concave surface facing the image side. This is composed of a cemented positive lens CL21 formed by bonding together. The third lens group G3 includes, in order from the object side, a positive meniscus lens L31 having an aspheric surface on the object side and a concave surface facing the object side, and a cemented negative lens CL31 formed by bonding a biconvex lens L32 and a biconcave lens L33. It is composed of The fourth lens group G4 includes, in order from the object side, a biconvex lens L41 having an aspheric surface on the image side, and a cemented negative lens CL41 formed by bonding the biconvex lens L42 and the biconcave lens L43. ing.

  Table 1 below lists values of specifications of the first embodiment. In Table 1, f is the focal length, FNO is the F number, 2ω is the angle of view, Bf is the back focus, Bf is the air conversion length from the lens surface closest to the image side (excluding the filter group FL) to the image surface. Respectively. Furthermore, the surface number is the order of the lens surfaces from the object side along the direction of travel of the light beam, the surface interval is the distance on the optical axis from each optical surface to the next optical surface, and the refractive index and Abbe number are each The value for the d-line (λ = 587.6 nm) is shown. The total length represents the distance on the optical axis from the first surface of the lens surface to the image plane I when focusing on infinity. Here, “mm” is generally used for the focal length, the radius of curvature, the surface interval, and other length units listed in all the following specifications, but the optical system is proportionally enlarged or reduced. However, the same optical performance can be obtained, and the present invention is not limited to this. The radius of curvature of 0.0000 indicates a plane, and the refractive index of air of 1.0000 is omitted. The description of these symbols and the description of the specification table are the same in the following embodiments.

(Table 1)
Wide angle end Intermediate focal length Telephoto end f = 10.56 to 15.00 to 106.05
F.NO = 2.87 to 3.05 to 4.56
2ω = 77.31 to 58.64 to 8.66
Image height = 7.95 to 7.95 to 7.95
Total lens length = 100.00 to 100.00 to 100.00
Air conversion Bf = 12.95 to 15.53 to 28.27

Surface number Curvature radius Surface spacing Refractive index Abbe number
1 50.3377 0.80 2.00069 25.46
2 28.2658 6.50 1.60300 65.44
3 578.7882 0.10
4 23.3079 3.44 1.67790 55.34
5 53.2836 (d5)
* 6 134.1627 0.85 1.82080 42.71
* 7 9.8631 3.94
8 -34.2586 0.75 1.78800 47.37
9 13.3897 2.36 1.94594 17.98
10 106.3816 (d10)
11 0.0000 0.50 (Aperture stop S)
* 12 -388.1977 1.34 1.59201 67.02
13 -34.1998 0.20 1.00000
14 20.4327 3.57 1.60300 65.44
15 -9.7026 0.75 1.83481 42.71
16 315.5138 (d16)
17 16.2471 6.00 1.51633 64.07
* 18 -67.0358 7.55
19 23.7200 5.48 1.49700 81.54
20 -10.0676 0.75 1.74400 44.79
21 80.7825 (d21)
22 0.0000 0.50 1.51680 64.10
23 0.0000 4.60 1.00000
24 0.0000 1.87 1.51680 64.10
25 0.0000 0.30 1.00000
26 0.0000 0.70 1.51680 64.10
27 0.0000 (Bf)

  In the first embodiment, the lens surfaces of the sixth surface, the seventh surface, the twelfth surface, and the eighteenth surface are formed in an aspherical shape. The following Table 2 shows the data of aspheric surfaces, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A10.

(Table 2)
R κ A4 A6 A8 A10
6th surface 134.1627 -9.0000 -6.2574E-05 1.5277E-06 -1.1303E-08 3.0606E-11
7th surface 9.8631 0.7892 -6.6591E-05 8.9298E-07 1.7565E-08 -1.0960E-11
12th surface -388.1977 -9.0000 6.0772E-05 4.2547E-07 4.4621E-09 8.7363E-11
18th surface -67.0358 0.7308 3.9489E-05 -7.0402E-08 -6.6982E-10 1.9741E-13

  In the first embodiment, the axial air distance d5 between the first lens group G1 and the second lens group G2, the axial air distance d10 between the second lens group G2 and the third lens group G3, and the third lens group G3. And the on-axis air gap d16 between the fourth lens group G4 and the on-axis air gap d21 between the fourth lens group G4 and the filter group FL change during zooming. Table 3 below shows variable intervals at each focal length in the wide-angle end state, the intermediate focal length state, and the telephoto end state.

(Table 3)
Wide angle end Intermediate focal length Telephoto end
f 10.5600 15.0000 106.0536
d5 1.0000 5.9263 23.7975
d10 23.7975 18.8711 1.0000
d16 16.3133 13.7423 1.0000
d21 5.4800 8.0512 20.7934
Bf 0.5499 0.5499 0.5498

  Table 4 below shows values corresponding to the conditional expressions in the first embodiment. In Table 4, f3 is the focal length of the third lens group G3, f4 is the focal length of the fourth lens group G4, f4F is the focal length of the front partial lens group G4F, and f4R is the rear partial lens group G4R. Each focal length is shown. The description of the above symbols is the same in the following embodiments.

(Table 4)
f3 = 46.5532
f4 = 26.6842
f4F = 25.9649
f4R = -97.9239
(1) f3 / f4 = 1.7446
(2) | f4R | /f4=3.6697
(3) | f4F | / | f4R | = 0.2652

  FIG. 3 is a diagram showing various aberrations of the first example with respect to the d-line (λ = 587.6 nm). 3A is an aberration diagram in the infinite focus state in the wide-angle end state (f = 10.56 mm), and FIG. 3B is an infinite point in the intermediate focal length state (f = 15.00 mm). FIG. 3C shows various aberrations in the infinite focus state in the telephoto end state (f = 106.05 mm). In each aberration diagram, FNO indicates an F number, Y indicates an image height, and A indicates a half field angle with respect to each image height. In the aberration diagrams showing astigmatism, the solid line shows the sagittal image plane, and the broken line shows the meridional image plane. Further, in the aberration diagrams showing the spherical aberration, the solid line shows the spherical aberration, and the broken line shows the sine condition (sine condition). The description of this aberration diagram is the same in the following examples. As is apparent from the respective aberration diagrams, in the first embodiment, 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]
FIG. 4 is a diagram illustrating a configuration of the zoom lens ZL2 according to the second embodiment. In the zoom lens ZL2 of FIG. 4, the first lens group G1 includes, in order from the object side, a cemented positive lens CL11 formed by bonding a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and an object It is composed of a positive meniscus lens L13 having a convex surface facing the side. The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having aspheric surfaces on both sides and a convex surface facing the object side, a biconcave lens L22, and a positive meniscus lens L23 having a concave surface facing the image side. This is composed of a cemented positive lens CL21 formed by bonding together. The third lens group G3 includes, in order from the object side, a biconvex lens L31 having an aspheric surface on the object side, and a cemented negative lens CL31 formed by bonding a biconvex lens L32 and a biconcave lens L33. The fourth lens group G4 includes, in order from the object side, a biconvex lens L41 having an aspheric surface on the image side, and a cemented negative lens CL41 formed by bonding the biconvex lens L42 and the biconcave lens L43. ing.

  Table 5 below shows values of specifications of the second embodiment.

(Table 5)
Wide angle end Intermediate focal length Telephoto end f = 10.56 to 55.00 to 106.05
F.NO = 2.88 to 4.33 to 4.51
2ω = 74.15-15.47-7.97
Image height = 7.50 to 7.50 to 7.50
Total lens length = 100.00 to 100.00 to 100.00
Air conversion Bf = 13.72 to 29.49 to 31.48

Surface number Curvature radius Surface spacing Refractive index Abbe number
1 91.9327 0.80 2.00069 25.46
2 40.2972 7.00 1.60300 65.44
3 -163.1562 0.10
4 28.0025 3.33 1.67790 55.34
5 77.5486 (d5)
* 6 103.0401 0.87 1.82080 42.71
* 7 12.6730 4.45
8 -17.8630 0.75 1.78800 47.37
9 16.7750 2.19 1.94594 17.98
10 575.1806 (d10)
11 0.0000 0.50 (Aperture stop S)
* 12 20.7903 2.20 1.59201 67.02
13 -33.6890 0.20
14 25.5552 2.90 1.60300 65.44
15 -15.3832 0.75 1.83481 42.71
16 27.2423 (d16)
17 23.4406 6.00 1.51633 64.07
* 18 -22.5663 1.63
19 14.7449 4.29 1.49700 81.54
20 -22.5133 0.75 1.74400 44.79
21 14.6450 (d21)
22 0.0000 0.50 1.51680 64.10
23 0.0000 4.60
24 0.0000 1.87 1.51680 64.10
25 0.0000 0.30
26 0.0000 0.70 1.51680 64.10
27 0.0000 (Bf)

  In the second embodiment, the lens surfaces of the sixth surface, the seventh surface, the twelfth surface, and the eighteenth surface are formed in an aspherical shape. Table 6 below shows the aspheric data, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A10.

(Table 6)
R κ A4 A6 A8 A10
6th surface 103.0401 4.9699 -3.7182E-05 1.4003E-06 -8.6436E-09 1.4864E-11
7th surface 12.6730 1.5231 -7.6892E-05 1.7203E-06 -1.3110E-08 2.4673E-10
12th surface 20.7903 -3.8086 5.5590E-05 -9.6180E-08 2.7763E-09 -2.3271E-11
18th surface -22.5663 5.6720 8.9839E-05 5.3558E-07 -1.1655E-09 6.5317E-11

  In the second embodiment, the axial air distance d5 between the first lens group G1 and the second lens group G2, the axial air distance d10 between the second lens group G2 and the third lens group G3, and the third lens group G3. And the on-axis air gap d16 between the fourth lens group G4 and the on-axis air gap d21 between the fourth lens group G4 and the filter group FL change during zooming. Table 7 below shows variable intervals at the respective focal lengths in the wide-angle end state, the intermediate focal length state, and the telephoto end state.

(Table 7)
Wide angle end Intermediate focal length Telephoto end
f 10.5600 54.9999 106.0536
d5 1.0265 19.7429 25.7219
d10 25.6955 6.9792 1.0000
d16 19.8176 4.0448 2.0518
d21 6.2446 22.0173 24.0104
Bf 0.5500 0.5500 0.5499

  Table 8 below shows values corresponding to the conditional expressions in the second embodiment.

(Table 8)
f3 = 32.6719
f4 = 30.0479
f4F = 23.3027
f4R = -46.3365
(1) f3 / f4 = 1.0873
(2) | f4R | /f4=1.5421
(3) | f4F | / | f4R | = 0.5029

  FIG. 5 is a diagram showing various aberrations of the second example with respect to the d-line (λ = 587.6 nm). That is, FIG. 5A is an aberration diagram in the infinitely focused state in the wide-angle end state (f = 10.56 mm), and FIG. 5B is an infinite point in the intermediate focal length state (f = 55.00 mm). FIG. 5C shows various aberrations in the infinite focus state in the telephoto end state (f = 106.05 mm). 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]
FIG. 6 is a diagram illustrating a configuration of a zoom lens ZL3 according to the third example. In the zoom lens ZL3 of FIG. 6, the first lens group G1 includes, in order from the object side, a cemented positive lens CL11 formed by bonding a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12, and an object It is composed of a positive meniscus lens L13 having a convex surface facing the side. The second lens group G2 includes, in order from the object side, a negative meniscus lens L21, a biconcave lens L22, and a biconvex lens L23 each having an aspheric surface on both sides and a convex surface facing the object side. The third lens group G3 includes, in order from the object side, a biconvex lens L31 having an aspheric surface on the object side, and a cemented negative lens CL31 formed by bonding a biconvex lens L32 and a biconcave lens L33. The fourth lens group G4 includes, in order from the object side, a biconvex lens L41 having an aspheric surface on the image side, and a cemented negative lens CL41 formed by bonding the biconvex lens L42 and the biconcave lens L43. ing.

  Table 9 below shows values of specifications of the third embodiment.

(Table 9)
Wide angle end Intermediate focal length Telephoto end f = 10.56 to 58.30 to 106.04
F.NO = 3.23 to 4.58 to 4.49
2ω = 76.89-15.46-8.43
Image height = 7.95 to 7.95 to 7.95
Total lens length = 100.00 to 99.99 to 99.99
Air conversion Bf = 13.51 to 30.96 to 30.29

Surface number Curvature radius Surface spacing Refractive index Abbe number
1 86.2725 0.80 2.00069 25.46
2 40.3250 6.80 1.60300 65.44
3 -183.7906 0.10
4 28.4025 3.19 1.67790 55.34
5 80.6543 (d5)
* 6 101.4124 0.85 1.82080 42.71
* 7 11.9136 5.00
8 -14.4685 0.75 1.78800 47.37
9 24.4369 0.22
10 25.2214 1.88 1.94594 17.98
11 -80.0724 (d11)
12 0.0000 0.50 (Aperture stop S)
* 13 19.6049 2.24 1.59201 67.02
* 14 -29.1984 0.27
15 20.8011 2.74 1.60300 65.44
16 -18.7156 1.99 1.83481 42.71
17 19.0668 (d17)
18 24.5490 6.50 1.51633 64.07
* 19 -20.4143 0.55
20 23.6982 4.02 1.49700 81.54
21 -15.0324 0.78 1.74400 44.79
22 25.2107 (d22)
23 0.0000 0.50 1.51680 64.10
24 0.0000 4.60
25 0.0000 1.87 1.51680 64.10
26 0.0000 0.30
27 0.0000 0.70 1.51680 64.10
28 0.0000 (Bf)

  In the third embodiment, the lens surfaces of the sixth surface, the seventh surface, the thirteenth surface, the fourteenth surface, and the nineteenth surface are formed in an aspherical shape. Table 10 below shows the data of the aspheric surface, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A10.

(Table 10)
R κ A4 A6 A8 A10
6th surface 101.4124 -9.0000 -5.3517E-05 2.5052E-06 -2.3244E-08 7.6766E-11
7th surface 11.9136 1.0603 -7.6365E-05 3.0755E-06 -1.3993E-08 1.3066E-10
13th surface 19.6049 -2.8837 5.6745E-05 -4.7155E-07 -7.3339E-10 -3.1854E-10
14th surface -29.1984 -0.8775 8.8143E-06 -4.7841E-07 9.8672E-10 -3.6990E-10
19th surface -20.4143 1.4260 3.4365E-05 4.7665E-07 -4.4841E-09 2.7577E-12

  In the third example, the axial air distance d5 between the first lens group G1 and the second lens group G2, the axial air distance d11 between the second lens group G2 and the third lens group G3, and the third lens group G3. And the on-axis air gap d17 between the fourth lens group G4 and the on-axis air gap d22 between the fourth lens group G4 and the filter group FL change during zooming. Table 11 below shows variable intervals at each focal length in the wide-angle end state, the intermediate focal length state, and the telephoto end state.

(Table 11)
Wide angle end Intermediate focal length Telephoto end
f 10.5597 58.3010 106.0356
d5 1.0000 20.7337 26.6840
d11 26.6842 6.9506 1.0000
d17 18.5762 1.1236 1.7891
d22 6.0400 23.4926 22.8272
Bf 0.5482 0.5435 0.5399

  Table 12 below shows values corresponding to the conditional expressions in the third embodiment.

(Table 12)
f3 = 28.9601
f4 = 32.9751
f4F = 22.7042
f4R = -44.8251
(1) f3 / f4 = 0.8782
(2) | f4R | /f4=1.3594
(3) | f4F | / | f4R | = 0.5065

  FIG. 7 is a diagram showing various aberrations of the third example with respect to the d-line (λ = 587.6 nm). 7A is an aberration diagram in the infinite focus state in the wide-angle end state (f = 10.56 mm), and FIG. 7B is an infinite point in the intermediate focal length state (f = 58.30 mm). FIG. 7C shows various aberrations in the infinite focus state in the telephoto end state (f = 106.04 mm). As is apparent from the respective aberration diagrams, in the third 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.

[Fourth embodiment]
FIG. 8 is a diagram illustrating a configuration of a zoom lens ZL4 according to the fourth example. In the zoom lens ZL3 of FIG. 8, the first lens group G1 is composed of, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a concave surface facing the image side. It is composed of a cemented positive lens CL11 and a positive meniscus lens L13 having a convex surface facing the object side. The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having aspheric surfaces on both sides and a convex surface facing the object side, a biconcave lens L22, and a positive meniscus lens L23 having a concave surface facing the image side. The cemented positive lens CL21. In order from the object side, the third lens group G3 includes a positive meniscus lens L31 having an aspheric surface on the object side and a concave surface facing the object side, and a biconvex lens L32 and a negative meniscus lens L33 having a concave surface facing the image side. It is composed of a cemented negative lens CL31 formed by bonding. The fourth lens group G4 includes, in order from the object side, a biconvex lens L41 having an aspheric surface on the image side, and a cemented negative lens CL41 formed by bonding the biconvex lens L42 and the biconcave lens L43. ing.

  Table 13 below lists values of specifications of the fourth embodiment.

(Table 13)
Wide angle end Intermediate focal length Telephoto end f = 10.56 to 15.00 to 106.05
F.NO = 2.91 to 3.05 to 4.67
2ω = 77.40 to 58.33 to 8.61
Image height = 7.95 to 7.95 to 7.95
Total lens length = 100.00 to 100.00 to 100.00
Air conversion Bf = 13.53 to 15.74 to 27.96

Surface number Curvature radius Surface spacing Refractive index Abbe number
1 54.4130 0.80 2.00069 25.46
2 29.7218 6.80 1.60300 65.44
3 1923.1428 0.10
4 24.3469 3.51 1.67790 55.34
5 56.3166 (d5)
* 6 112.1340 0.85 1.82080 42.71
* 7 10.2646 3.95
8 -27.9793 0.75 1.78800 47.37
9 13.9198 2.32 1.94594 17.98
10 126.3014 (d10)
11 0.0000 0.50 (Aperture stop S)
* 12 -676.8880 1.43 1.59201 67.02
13 -31.9148 0.31
14 21.7527 3.82 1.60300 65.44
15 -9.0792 0.75 1.83481 42.71
16 -382.0200 (d16)
17 20.4085 4.45 1.51633 64.07
* 18 -29.5490 (d18)
19 24.6510 4.62 1.49700 81.54
20 -11.2874 0.75 1.74400 44.79
21 36.9005 (d21)
22 0.0000 0.50 1.51680 64.10
23 0.0000 4.60
24 0.0000 1.87 1.51680 64.10
25 0.0000 0.30
26 0.0000 0.70 1.51680 64.10
27 0.0000 (Bf)

  In the fourth embodiment, the lens surfaces of the sixth surface, the seventh surface, the twelfth surface, and the eighteenth surface are formed in an aspherical shape. Table 14 below shows the data of aspheric surfaces, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A10.

(Table 14)
R κ A4 A6 A8 A10
6th surface 112.1340 4.7971 -5.5223E-05 1.1187E-06 -6.1569E-09 1.1357E-11
7th 10.2646 1.3118 -1.1438E-04 2.3126E-08 7.2482E-09 2.1876E-12
12th surface -676.8880 6.0000 6.0950E-05 7.1004E-07 -8.1338E-09 3.3527E-10
18th surface -29.5490 3.0096 3.9534E-05 -1.2059E-08 -2.1096E-10 -2.1064E-12

  In the fourth embodiment, the axial air distance d5 between the first lens group G1 and the second lens group G2, the axial air distance d10 between the second lens group G2 and the third lens group G3, and the third lens group G3. Between the front lens group G4F and the rear lens group G4R of the fourth lens group G4, and the rear lens group G4R of the fourth lens group G4. The on-axis air distance d21 between the filter group FL and the filter group FL changes during zooming. Table 15 below shows variable intervals at the respective focal lengths in the wide-angle end state, the intermediate focal length state, and the telephoto end state.

(Table 15)
Wide angle end Intermediate focal length Telephoto end
f 10.5600 15.0000 106.0520
d5 1.0000 6.2368 24.3139
d10 24.3139 19.0771 1.0000
d16 17.7536 15.1432 1.0000
d18 6.6294 7.0333 8.9555
d21 6.0603 8.2668 20.4873
Bf 0.5501 0.5501 0.5493

  Table 16 below shows values corresponding to the conditional expressions in the fourth embodiment.

(Table 16)
f3 = 40.7456
f4 = 28.8135
f4F = 24.1110
f4R = -51.8979
(1) f3 / f4 = 1.4141
(2) | f4R | /f4=1.801
(3) | f4F | / | f4R | = 0.4646

  FIG. 9 is a diagram of various aberrations of the fourth example for the d-line (λ = 587.6 nm). 9A is an aberration diagram in the infinite focus state in the wide-angle end state (f = 10.56 mm), and FIG. 9B is infinite in the intermediate focal length state (f = 15.00 mm). FIG. 9C shows various aberrations in the infinite focus state in the telephoto end state (f = 106.05 mm). As is apparent from the respective aberration diagrams, in the fourth 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.

[Fifth embodiment]
FIG. 10 is a diagram illustrating a configuration of a zoom lens ZL5 according to the fifth example. In the zoom lens ZL5 of FIG. 10, the first lens group G1 is composed of, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side and a biconvex lens L12 having an aspheric surface on the image side. It is composed of a cemented positive lens CL11. The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having aspheric surfaces on both sides and a convex surface facing the object side, a biconcave lens L22, and a positive meniscus lens L23 having a concave surface facing the image side. The cemented positive lens CL21. The third lens group G3 includes, in order from the object side, a biconvex lens L31 having an aspheric surface on the object side, and a cemented negative lens CL31 formed by bonding a biconvex lens L32 and a biconcave lens L33. The fourth lens group G4 includes, in order from the object side, a biconvex lens L41 having an aspheric surface on the image side, and a cemented negative lens CL41 formed by bonding the biconvex lens L42 and the biconcave lens L43. ing.

  Table 17 below provides values of specifications of the fifth embodiment.

(Table 17)
Wide angle end Intermediate focal length Telephoto end f = 14.00 to 20.00 to 106.05
F.NO = 3.07 to 3.24 to 4.51
2ω = 62.10 to 45.32 to 8.20
Image height = 7.90 to 7.90 to 7.90
Total lens length = 75.00 to 75.00 to 75.00
Air equivalent Bf = 9.31 to 12.84 to 17.65

Surface number Curvature radius Surface spacing Refractive index Abbe number
1 19.6256 0.80 1.92286 20.88
2 16.5739 6.55 1.49700 81.54
* 3 -171.0121 (d3)
* 4 30.0165 0.85 1.82080 42.71
* 5 10.8296 3.50
6 -16.5517 0.75 1.81600 46.62
7 11.7047 2.20 1.92286 18.90
8 63.0904 (d8)
9 0.0000 0.50 (Aperture stop S)
* 10 12.2474 3.37 1.58913 61.25
11 -29.2528 0.20
12 21.3790 4.00 1.65160 58.55
13 -9.5440 0.75 1.83400 37.16
14 15.3225 (d14)
15 16.1551 2.53 1.51633 64.07
* 16 -39.5952 4.56
17 69.2267 4.34 1.62004 36.26
18 -6.4668 0.75 1.72000 46.02
19 22.7319 (d19)
20 0.0000 0.65 1.54437 70.51
21 0.0000 0.40
22 0.0000 0.50 1.51633 64.14
23 0.0000 (Bf)

  In the fifth embodiment, the third, fourth, fifth, tenth, and sixteenth lens surfaces are aspherical. Table 18 below shows the data of aspheric surfaces, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A10.

(Table 18)
R κ A4 A6 A8 A10
3rd surface -171.0121 -9.0000 1.1300E-05 -1.3879E-08 -9.3365E-13 1.4898E-13
4th surface 30.0165 10.9709 -9.1986E-05 -4.6047E-06 1.3916E-07 -9.3684E-10
5th surface 10.8296 2.4932 -2.1280E-04 -5.7364E-06 2.6836E-08 1.4262E-09
10th surface 12.2474 -2.1554 1.5930E-04 -5.7085E-07 2.4628E-09 1.0576E-10
16th surface -39.5952 0.2787 6.3760E-05 2.6128E-07 -2.3507E-08 1.0723E-10

  In the fifth embodiment, the on-axis air distance d3 between the first lens group G1 and the second lens group G2, the on-axis air distance d8 between the second lens group G2 and the third lens group G3, and the third lens group G3. The on-axis air distance d14 between the fourth lens group G4 and the on-axis air distance d19 between the fourth lens group G4 and the filter group FL changes during zooming. Table 19 below shows variable intervals at each focal length in the wide-angle end state, the intermediate focal length state, and the telephoto end state.

(Table 19)
Wide angle end Intermediate focal length Telephoto end
f 14.0000 20.0000 106.0543
d3 1.0000 4.6957 20.0201
d8 20.0492 16.3539 1.0292
d14 8.5898 5.0615 0.2464
d19 7.5582 11.0866 15.9017
Bf 0.6000 0.6000 0.6002

  Table 20 below shows values corresponding to the conditional expressions in the fifth embodiment.

(Table 20)
f3 = 21.5180
f4 = 43.6821
f4F = 22.5702
f4R = -26.9335
(1) f3 / f4 = 0.4926
(2) | f4R | /f4=0.6166
(3) | f4F | / | f4R | = 0.8380

  FIG. 11 is a diagram illustrating various aberrations of the fifth example with respect to the d-line (λ = 587.6 nm). That is, FIG. 11A is an aberration diagram in the infinite focus state in the wide-angle end state (f = 14.00 mm), and FIG. 11B is infinite in the intermediate focal length state (f = 20.00 mm). FIG. 11C shows various aberrations in the infinite focus state in the telephoto end state (f = 106.05 mm). As is apparent from each aberration diagram, in the fifth 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.

It is refractive power arrangement | positioning of the zoom lens by this embodiment. It is sectional drawing which shows the structure of the zoom lens by 1st Example. FIG. 5A is a diagram illustrating various aberrations of the first example, FIG. 10A is an aberration diagram in an infinite focus state in a wide-angle end state, and FIG. 10B is an aberration diagram in an infinite focus state in an intermediate shooting distance state. Yes, (c) shows various aberrations in the infinitely focused state in the telephoto end state. It is sectional drawing which shows the structure of the zoom lens by 2nd Example. FIG. 4A is a diagram illustrating various aberrations of the second example, and FIG. 4A is an aberration diagram in an infinite focus state in a wide-angle end state, and FIG. 4B is an aberration diagram in an infinite focus state in an intermediate shooting distance state. Yes, (c) shows various aberrations in the infinitely focused state in the telephoto end state. It is sectional drawing which shows the structure of the zoom lens by 3rd Example. FIG. 9A is a diagram illustrating various aberrations of the third example, FIG. 10A is an aberration diagram in an infinite focus state in a wide-angle end state, and FIG. 9B is an aberration diagram in an infinite focus state in an intermediate shooting distance state. Yes, (c) shows various aberrations in the infinitely focused state in the telephoto end state. It is sectional drawing which shows the structure of the zoom lens by 4th Example. FIG. 9A is a diagram illustrating various aberrations of the fourth example, FIG. 10A is an aberration diagram in an infinite focus state in a wide-angle end state, and FIG. 9B is an aberration diagram in an infinite focus state in an intermediate shooting distance state. Yes, (c) shows various aberrations in the infinitely focused state in the telephoto end state. It is sectional drawing which shows the structure of the zoom lens by 5th Example. FIG. 9A is a diagram illustrating various aberrations of the fifth example. FIG. 10A is an aberration diagram in the infinite focus state in the wide-angle end state. FIG. 10B is an aberration diagram in the infinite focus state in the intermediate shooting distance state. Yes, (c) shows various aberrations in the infinitely focused state in the telephoto end state. 1 is a cross-sectional view of a digital single-lens reflex camera equipped with a zoom lens according to the present embodiment. 5 is a flowchart for explaining a method of manufacturing a zoom lens according to the present embodiment.

Explanation of symbols

ZL (ZL1 to ZL5) Zoom lens G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group (lens group arranged closest to the image side)
G4F Front lens group G4R Rear lens group S Aperture stop 1 Digital single-lens reflex camera (optical equipment)

Claims (19)

From the object 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 a positive refractive power,
When zooming from the wide-angle end state to the telephoto end state, the first lens group is fixed with respect to the image plane, the distance between the first lens group and the second lens group changes, and the second lens At least the second lens group and the fourth lens group move so that the distance between the third lens group and the third lens group changes, and the distance between the third lens group and the fourth lens group changes. ,
The fourth lens group includes a front partial lens group and a rear partial lens group disposed on the image side of the front partial lens group with an air gap therebetween, and the rear partial lens group is arranged in the optical axis direction. A zoom lens that moves and focuses.   2. The zoom lens according to claim 1, wherein at least one of the third lens group and the fourth lens group includes one positive single lens and one cemented lens.   The object-side lens surface of the single lens is convex toward the object side, the object-side lens surface of the cemented lens is convex toward the object side, and the image-side lens surface of the cemented lens is image-side The zoom lens according to claim 2, wherein the zoom lens has a concave shape.   The zoom lens according to any one of claims 1 to 3, wherein the rear lens group in the fourth lens group has a negative refractive power.   The rear partial lens group in the fourth lens group moves in the optical axis direction integrally with the front partial lens group in the infinite focus state when zooming from the wide-angle end state to the telephoto end state. The zoom lens according to claim 1, wherein the zoom lens is configured as follows.   The front lens group and the rear lens group in the fourth lens group are configured to move in the optical axis direction at different speeds when zooming from the wide-angle end state to the telephoto end state. Item 5. The zoom lens according to any one of Items 1 to 4.   The zoom lens according to claim 1, wherein the front lens group in the fourth lens group has a positive refractive power.   The zoom lens according to claim 1, wherein all of the optical elements included in the first lens group each have a refractive power. When the focal length of the third lens group is f3 and the focal length of the fourth lens group is f4, the following expression 0.1 <f3 / f4 <3.0
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.   The zoom lens according to claim 1, further comprising an aperture stop between the second lens group and the third lens group.   The zoom lens according to claim 1, wherein the third lens group includes at least one aspheric lens. When the focal length of the fourth lens group is f4 and the focal length of the rear lens group is f4R, the following expression 0.1 <| f4R | / f4 <6.7
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition. When the focal length of the front lens group is f4F and the focal length of the rear lens group is f4R, the following expression 0.1 <| f4F | / | f4R | <1.5
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.   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. The zoom lens according to claim 1, wherein an interval between the third lens group and the fourth lens group decreases.   The zoom lens according to claim 1, wherein the third lens group is fixed with respect to the image plane when zooming from the wide-angle end state to the telephoto end state.   The zoom lens according to claim 1, wherein at least a part of the third lens group moves so as to have a component in a direction substantially perpendicular to the optical axis. From the object 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,
When zooming from the wide-angle end state to the telephoto end state, the first lens group is fixed with respect to the image plane, the distance between the first lens group and the second lens group changes, and the second lens At least the second lens group and the fourth lens group move so that the distance between the third lens group and the third lens group changes, and the distance between the third lens group and the fourth lens group changes. ,
All of the optical elements included in the first lens group each have refractive power,
The lens group arranged closest to the image side is a zoom lens having a lens component whose position on the optical axis is fixed during focusing and a lens component that moves in the optical axis direction during focusing.   An optical apparatus comprising the zoom lens according to claim 1, wherein an image of an object is formed on a predetermined image plane. In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power A zoom lens manufacturing method comprising:
When zooming from the wide-angle end state to the telephoto end state, the first lens group is fixed with respect to the image plane, the distance between the first lens group and the second lens group changes, and the second lens group changes. At least the second lens group and the fourth lens group move so that the distance between the lens group and the third lens group changes and the distance between the third lens group and the fourth lens group changes. Arranged to
In the fourth lens group, a front partial lens group, and a rear partial lens group disposed with an air gap on the image side of the front partial lens group,
A zoom lens manufacturing method in which the rear partial lens group is moved in the optical axis direction so as to be focused.

Images