JP6938843B2 - Zoom lenses and optics - Google Patents

Description

The present invention relates to a zoom lens and an optical device .

Conventionally, 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 group arranged in order from the object side along the optical axis. A zoom lens consisting of a fourth lens group having a refractive power and a fifth lens group having a positive refractive power and moving at least four lens groups to perform scaling has been proposed (see, for example, Patent Document 1). .. In the conventional zoom lens, the magnification ratio is limited to about 30 times, and it is difficult to maintain good performance while maintaining the size at a higher magnification.

Japanese Unexamined Patent Publication No. 2011-186417

The zoom lens according to the present invention has a first lens group having a positive refractive index, a second lens group having a negative refractive index, and a positive refractive index arranged in order from the object side along the optical axis. It is composed of substantially five lens groups, that is, a third lens group, a fourth lens group having a negative refractive index, and a fifth lens group having a positive refractive force, and the first lens group has three lenses. With the above lenses, the distance between adjacent lens groups changes when the magnification is changed from the wide-angle end state to the telescopic end state, and the fifth lens group is fixedly held at the time of magnification change. I am satisfied.
1.750 <νd1Av / (ft / fw) <1.900
2.800 <M3 / M4 <4.10
However, νd1Av: the average Abbe number of the d-line of the lens in the first lens group fw: the focal length of the entire zoom lens at the wide-angle end ft: the focal length of the entire zoom lens at the telephoto end M3: the third lens Amount of movement from the wide-angle end to the telephoto end of the group M4: Amount of movement from the wide-angle end to the telephoto end of the fourth lens group (each movement amount is positive for movement toward the object side )

The optical device according to the present invention is configured to include the above zoom lens.

It is sectional drawing which shows the lens structure of the zoom lens which concerns on 1st Example of this Embodiment. 2 (a), 2 (b), and 2 (c) are aberration diagrams of the zoom lens according to the first embodiment in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. It is sectional drawing which shows the lens structure of the zoom lens which concerns on 2nd Example of this Embodiment. 4 (a), 4 (b), and 4 (c) are aberration diagrams of the zoom lens according to the second embodiment in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. It is sectional drawing which shows the lens structure of the zoom lens which concerns on 3rd Example of this Embodiment. 6 (a), 6 (b), and 6 (c) are aberration diagrams of the zoom lens according to the third embodiment in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. It is sectional drawing which shows the lens structure of the zoom lens which concerns on 4th Example of this Embodiment. 8 (a), 8 (b), and 8 (c) are aberration diagrams of the zoom lens according to the fourth embodiment in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. It is the schematic which shows the structure of the camera provided with the zoom lens which concerns on this embodiment. It is a flowchart which shows the outline of the manufacturing method of the zoom lens which concerns on this embodiment.

Hereinafter, embodiments will be described with reference to the drawings. As shown in FIG. 1, the zoom lens ZL (1) as an example of the zoom lens ZL according to the present embodiment is a first lens group G1 having a positive refractive index, which is arranged in order from the object side along the optical axis. After including a second lens group G2 having a negative refractive index, a third lens group G3 having a positive refractive index, a fourth lens group G4 having a negative refractive index, and one or more lens groups. It has a group lens group GR, and the first lens group G1 has three or more lenses, and the distance between adjacent lens groups changes when the magnification is changed from the wide-angle end state to the telescopic end state. Conditional expression (1) of is satisfied.

1.750 <νd1Av / (ft / fw) <1.900 ・ ・ ・ (1)
However, νd1Av: the average Abbe number of the d-line of the lens in the first lens group G1 fw: the focal length of the entire zoom lens at the wide-angle end ft: the focal length of the entire zoom lens at the telephoto end

The zoom lens ZL according to the present embodiment may be the zoom lens ZL (2) shown in FIG. 3, the zoom lens ZL (3) shown in FIG. 5, or the zoom lens ZL (4) shown in FIG.

By configuring the zoom lens ZL of the present embodiment as described above, it is possible to realize a zoom lens having high magnification and high optical performance. Conditional expression (1) defines the ratio of the average Abbe number of lenses in the first lens group G1 to the ratio of the focal length at the wide-angle end to the telephoto end: ft / fw (that is, the magnification MagWT of the lens barrel). Is. By satisfying the conditional equation (1), axial chromatic aberration, chromatic aberration of magnification, spherical aberration, and coma at the time of scaling can be reduced.

Below the lower limit of the conditional equation (1), the average Abbe number of the first lens group G1 is small and the refractive index is strong with respect to the variable magnification from the wide-angle end to the telephoto end, so that axial chromatic aberration and magnification at the telephoto end are increased. It becomes difficult to suppress chromatic aberration. In order to ensure the effect of this embodiment, it is preferable that the lower limit value of the conditional expression (1) is 1.760.

On the other hand, if the upper limit of the conditional expression (1) is exceeded, the refractive index of the first lens group G1 becomes weaker with respect to the scaling from the wide-angle end to the telephoto end, so that it is necessary to increase the lens barrel size. By reducing the curvature of each lens of the first lens group G1 and increasing the refractive power of the first lens group, it is possible to suppress an increase in the lens barrel size, but suppress spherical aberration and coma. Becomes difficult. Further, it is conceivable to increase the refractive power of the third lens group G3 to suppress the lens barrel size, but it is also difficult to suppress spherical aberration and coma aberration at this time. In addition, in order to ensure the effect of this embodiment, it is preferable to set the upper limit value of the conditional expression (1) to 1.870. Further, in order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of the conditional expression (1) to 1.850.

The zoom lens ZL according to the present embodiment preferably satisfies the following conditional expression (2).
3.800 <f4 / f2 <4.250 ... (2)
However, f2: focal length of the second lens group G2 f4: focal length of the fourth lens group G4

Conditional expression (2) defines the ratio of the focal lengths of the second lens group G1 and the fourth lens group G4, and by keeping this ratio within the above range, spherical aberration and eccentric sensitivity can be reduced. The eccentric sensitivity indicates the ratio of deterioration of optical performance such as coma aberration to the amount of eccentricity of the lens.

The case where the value is below the lower limit of the conditional expression (2) will be described. Being below the lower limit of the conditional expression (2) means that the focal length f2 of the second lens group G2 becomes larger or the focal length f4 of the fourth lens group G4 becomes smaller. When the focal length f2 of the second lens group G2 is increased, the spherical aberration correction ability of the second lens group G2 is lowered, and the spherical aberration at the telephoto end is particularly deteriorated. To compensate for this, it is conceivable to increase the moving distance of the second lens group G2, but this will increase the lens barrel size. Further, when the focal length f4 of the fourth lens group G4 becomes smaller, the eccentric sensitivity of the fourth lens group G4 becomes higher, and the optical performance is likely to deteriorate due to assembly variations during manufacturing. In order to ensure the effect of this embodiment, it is preferable that the lower limit value of the conditional expression (2) is 3.84.

On the other hand, when the upper limit value of the conditional expression (2) is exceeded, the focal length f2 of the second lens group G2 becomes smaller, or the focal length f4 of the fourth lens group G4 becomes larger. When the focal length f2 of the second lens group G2 becomes smaller, the spherical aberration correction ability of the second lens group G2 becomes too strong, and the spherical aberration at the telephoto end becomes particularly worse. Further, the eccentric sensitivity of the second lens group G2 becomes high, and the optical performance is liable to deteriorate due to assembly variations during manufacturing. Further, when the focal length f4 of the fourth lens group G4 becomes large, the amount of movement of the fourth lens group G4 at the time of focusing increases, so that the lens barrel size becomes long. In order to ensure the effect of this embodiment, it is preferable to set the upper limit value of the conditional expression (2) to 4.210.

The zoom lens ZL according to the present embodiment preferably satisfies the following conditional expression (3).
0.360 <f1 / ft <0.400 ... (3)
However, f1: the focal length of the first lens group G1

Conditional expression (3) defines the ratio of the focal length f1 of the first lens group G1 to the focal length ft of the entire zoom lens group at the telephoto end, and by keeping this ratio within the above range, the zoom can be obtained. Spherical aberration and coma aberration in the telephoto end state of the lens can be suppressed.

If it falls below the lower limit of the conditional expression (3), the refractive power of the first lens group G1 in the telephoto end state is too strong. Therefore, the spherical aberration generated in the first lens group G1 becomes strong, and it becomes difficult to correct the spherical aberration and the coma aberration at the telephoto end. In order to ensure the effect of this embodiment, it is preferable to set the lower limit value of the conditional expression (3) to 0.364.

If the upper limit of the conditional expression (3) is exceeded, the refractive power of the first lens group G1 in the telephoto end state is too weak. Therefore, it is necessary to increase the total length of the lens barrel at the telephoto end. Correspondingly, it is conceivable to increase the refractive power of the third lens group G3 to maintain the total length. In this case, the third lens group G3 is strengthened by increasing the refractive power of the third lens group G3. It becomes difficult to correct spherical aberration and coma aberration generated in G3. In order to ensure the effect of this embodiment, it is preferable to set the upper limit value of the conditional expression (3) to 0.396.

The zoom lens ZL according to the present embodiment preferably satisfies the following conditional expression (4).
3.600 <(1-β3t) x βRt <3.90 ・ ・ ・ (4)
However, β3t: lateral magnification at the telephoto end of the third lens group G3 βRt: combined lateral magnification at the telephoto end of the lens group arranged on the image plane side of the third lens group G3.

The conditional expression (4) defines an appropriate range of the blur sensitivity coefficient (= (1-β3t) × βRt) of the third lens group G3 in the telephoto end state, and satisfies the conditional expression (4). When the blur sensitivity coefficient is set, camera shake correction can be effectively performed when vibration isolation is performed by the third lens group G3. The blur sensitivity coefficient indicates the ratio of the image movement amount in the direction perpendicular to the optical axis to the lens eccentricity amount.

When the value is lower than the lower limit of the conditional expression (4), the lateral magnification of the third lens group G3 is small, and the lens group arranged on the image plane side of the third lens group (for example, the fourth lens group G4 and the rear lens group). It is conceivable that the combined lateral magnification of the group lens group GR (fifth lens group G5)) is large. In this case, strong spherical aberration occurs in the fourth lens group G4 and the rear group lens group GR (fifth lens group G5), and the spherical aberration and coma aberration at the telephoto end are exacerbated. Further, it is conceivable that the lateral magnification of the third lens group G3 is large and the lateral magnification of the fourth lens group G4 and the rear group lens group GR (fifth lens group G5) is small. Since it is necessary to increase the magnification of the lens group G3, spherical aberration and coma in the telephoto end state are deteriorated. In order to ensure the effect of this embodiment, it is preferable to set the lower limit value of the conditional expression (4) to 3.640.

On the other hand, when the upper limit of the conditional expression (4) is exceeded, the lateral magnification of the third lens group G3 is large, and the fourth lens group G4 and the rear group lens group arranged on the image plane side of the third lens group It is conceivable that the combined lateral magnification of GR (fifth lens group G5) is small. In this case, the spherical aberration correction ability of the fourth lens group and the rear group lens group GR (fifth lens group G5) is reduced, and the spherical aberration and coma aberration in the telephoto end state are deteriorated. On the contrary, it is conceivable that the lateral magnification of the third lens group G3 is small and the combined lateral magnification of the fourth lens group G4 and the rear group lens group GR (fifth lens group G5) is large. It is necessary to reduce the lateral magnification of the third lens group G3, which worsens spherical aberration and coma. In order to ensure the effect of this embodiment, it is preferable to set the upper limit value of the conditional expression (4) to 3.860.

The zoom lens ZL according to the present embodiment preferably satisfies the following conditional expression (5).
2.800 <M3 / M4 <4.10 ... (5)
However, M3: the amount of movement of the third lens group G3 from the wide-angle end to the telephoto end M4: the amount of movement of the fourth lens group G4 from the wide-angle end to the telephoto end (each movement amount is positive for the movement toward the object side).

Conditional expression (5) defines the ratio of the amount of movement of the third and fourth lens groups G3 and G4 from the wide-angle end to the telephoto end. By configuring this ratio (M3 / M4) to be within the above range, it is possible to reduce fluctuations in spherical aberration and coma aberration during scaling.

When the value is lower than the lower limit of the conditional expression (5), it is conceivable that the amount of movement of the third lens group G3 is small and the amount of movement of the fourth lens group G4 is large. When the amount of movement of the third lens group G3 is small, it is necessary to strengthen the scaling effect of the third lens group G3, the magnification of the third lens group G3 becomes strong, and the spherical aberration in the third lens group G3 becomes large. , Spherical aberration and coma aberration in the entire variable magnification worsen. Further, when the amount of movement of the fourth lens group G4 is large, it is necessary to weaken the scaling effect of the fourth lens group G4, the correction of the spherical aberration of the entire system becomes insufficient, and the spherical aberration and the coma aberration worsen. In order to ensure the effect of this embodiment, it is preferable that the lower limit value of the conditional expression (5) is 2.850.

On the other hand, when the upper limit value of the conditional expression (5) is exceeded, it is conceivable that the amount of movement of the third lens group G3 is large and the amount of movement of the fourth lens group G4 is small. When the amount of movement of the third lens group G3 is large, the lens barrel size at the telephoto end becomes long, and when trying to maintain the lens barrel size, spherical aberration and coma aberration in the entire variable magnification range worsen. Further, when the amount of movement of the fourth lens group G4 is small, it is necessary to strengthen the scaling effect of the fourth lens group G4, the eccentric sensitivity of the fourth lens group G4 becomes high, and due to assembly variations during manufacturing and the like. Optical performance is likely to deteriorate. In order to ensure the effect of this embodiment, it is preferable that the upper limit of the conditional expression (5) is 4.000.

The zoom lens ZL according to the present embodiment preferably satisfies the following conditional expression (6).
15.0 <ωw <65.0 ・ ・ ・ (6)
However, ωw: Half angle of view of the entire zoom lens at the wide-angle end (unit: degree)

The conditional expression (6) is a conditional expression that defines the optimum value of the half angle of view at the wide-angle end. By satisfying the conditional expression (6), various aberrations such as coma, curvature of field, and distortion can be satisfactorily corrected while having a wide half-angle of view.

In order to ensure the effect of this embodiment, it is preferable to set the lower limit value of the conditional expression (6) to 20.0. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit value of the conditional expression (6) to 25.0. Further, in order to make the effect of this embodiment more certain, it is preferable to set the lower limit value of the conditional expression (6) to 30.0. Further, in order to make the effect of this embodiment more certain, it is preferable to set the lower limit value of the conditional expression (6) to 35.0. Further, in order to make the effect of this embodiment more certain, it is preferable to set the lower limit value of the conditional expression (6) to 38.0. Further, in order to make the effect of this embodiment more certain, it is preferable to set the lower limit value of the conditional expression (6) to 40.0.

On the other hand, in order to ensure the effect of this embodiment, it is preferable to set the upper limit value of the conditional expression (6) to 60.0. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of the conditional expression (6) to 55.0. Further, in order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of the conditional expression (6) to 50.0. Further, in order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of the conditional expression (6) to 47.0.

The zoom lens ZL according to the present embodiment preferably satisfies the following conditional expression (7).
0.5 <ωt <7.0 ・ ・ ・ (7)
However, ωt: Half angle of view of the entire zoom lens at the telephoto end (unit: degree)

The conditional expression (7) is a conditional expression that defines the optimum value of the half angle of view at the telephoto end. By satisfying the conditional equation (7), various aberrations such as coma, curvature of field, and distortion can be satisfactorily corrected.

In order to ensure the effect of this embodiment, it is preferable to set the lower limit value of the conditional expression (7) to 0.7. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit value of the conditional expression (7) to 1.0. Further, in order to make the effect of this embodiment more certain, it is preferable to set the lower limit value of the conditional expression (7) to 1.2. Further, in order to make the effect of this embodiment more certain, it is preferable to set the lower limit value of the conditional expression (7) to 1.3.

On the other hand, in order to ensure the effect of this embodiment, it is preferable to set the upper limit value of the conditional expression (7) to 6.0. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of the conditional expression (7) to 5.0. Further, in order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of the conditional expression (7) to 4.0. Further, in order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of the conditional expression (7) to 3.0. Further, in order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of the conditional expression (7) to 2.5.

In the zoom lens ZL according to the present embodiment, it is preferable that the lens group (for example, the fifth lens group G5) located on the image side of the rear group lens group GR is fixedly held at the time of scaling. As a result, fluctuations in spherical aberration, distortion, etc. at the time of scaling can be suppressed.

In the zoom lens ZL according to the present embodiment, it is preferable that the third lens group G3 has at least one aspherical lens. As a result, the optical performance of the zoom lens ZL can be further improved.

In the zoom lens ZL according to the present embodiment, it is preferable that at least a part of the fourth lens group G4 is a focusing lens. This makes it possible to reduce fluctuations in various aberrations such as spherical aberration and coma during focusing. When focusing on a short-range object from infinity, at least a part of the fourth lens group G4 constituting the focusing lens moves toward the image side in the optical axis direction.

In the zoom lens ZL according to the present embodiment, it is preferable that at least a part of the third lens group G3 constitutes a vibration-proof lens group having a displacement component in the direction perpendicular to the optical axis. This makes it possible to reduce fluctuations in various aberrations such as coma during image stabilization.

According to the zoom lens ZL according to the present embodiment having the above configuration, it is possible to realize a zoom lens having good optical performance while having high magnification.

The optical device of the present embodiment is configured to include the zoom lens ZL having the above-described configuration. As a specific example thereof, a camera (optical device) provided with the zoom lens ZL will be described with reference to FIG. As shown in FIG. 9, the camera 1 is a digital camera provided with the zoom lens ZL according to the above embodiment as the photographing lens 2. In the camera 1, the light from an object (subject) (not shown) is collected by the photographing lens 2 and reaches the image sensor 3. As a result, the light from the subject is captured by the image sensor 3 and recorded as a subject image in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1. This camera may be a mirrorless camera or a single-lens reflex type camera having a quick return mirror. Although not shown, the camera 1 is also provided with an auxiliary light emitting unit that emits auxiliary light when the subject is dark, a function button used for setting various conditions of the digital still camera, and the like.

Here, a compact type camera in which the camera 1 and the zoom lens ZL are integrally molded is illustrated, but as an optical device, a single-lens reflex camera in which the lens barrel having the zoom lens ZL and the camera body body can be attached and detached is also used. good.

According to the camera 1 according to the present embodiment having the above configuration, by mounting the above-mentioned zoom lens ZL as a photographing lens, it is possible to realize a camera having good optical performance while having high magnification. Can be done.

Subsequently, the method for manufacturing the zoom lens ZL described above will be described with reference to FIG. First, in the lens barrel, in order from the object side along the optical axis, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a first lens group having a positive refractive power. The three lens group G3, the fourth lens group G4 having a negative refractive power, and the rear group lens group GR including one or more lens groups are arranged side by side in the lens barrel (step ST1). At this time, the first lens group G1 is configured to have three or more lenses. Next, when the magnification is changed from the wide-angle end state to the telephoto end state, the distance between adjacent lens groups is changed (step ST2). Further, it is configured so as to satisfy the above conditional expression (1) (step ST3).

According to the manufacturing method according to the present embodiment as described above, it is possible to manufacture a zoom lens ZL having good optical performance while having a high magnification.

Hereinafter, the zoom lens ZL according to the embodiment of the present embodiment will be described with reference to the drawings. 1, FIG. 3, FIG. 5, and FIG. 7 are cross-sectional views showing the configuration and the like of the zoom lenses ZL {ZL (1) to ZL (4)} according to the first to fourth embodiments. Each cross-sectional view describes the position of each lens group when scaling from the wide-angle end state (W) to the telephoto end state (T) via the intermediate focal length (intermediate angle of view) state (M). .. The arrows shown in the middle of these figures indicate the moving directions of the first to fourth lens groups G1 to G4 when zooming from the wide-angle end state to the telephoto end state via the intermediate focal length state. There is. The fifth lens group G5 is held stationary.

In these figures, each lens group is represented by a combination of reference numerals G and numbers, and each lens is represented by a combination of reference numerals L and numbers. In this case, in order to prevent the types and numbers of the symbols and numbers from becoming large and complicated, the lens group and the like are represented by independently using combinations of the symbols and numbers for each embodiment. Therefore, even if the same combination of reference numerals and numbers is used between the examples, it does not mean that they have the same configuration.

Tables 1 to 4 are shown below, which are tables showing each specification data in the first to fourth embodiments.

In the [Lens Specifications] table, the surface numbers indicate the order of the optical surfaces from the object side along the direction in which the light beam travels, and R is the radius of curvature of each optical surface (the surface whose center of curvature is located on the image side). (Positive value), D is the distance on the optical axis from each optical surface to the next optical surface, nd is the refractive index of the material of the optical member with respect to the d line (wavelength 587.6 nm), and νd is optical. The Abbe number based on the d-line of the material of the member is shown. The surface number indicates the order of the lens surfaces from the object side along the traveling direction of the light beam. The radius of curvature "∞" indicates a plane or an aperture, and (aperture S) indicates an aperture stop S. The description of the refractive index nd of air = 1.00000 is omitted. When the lens surface is aspherical, the surface number is marked with * and the radius of curvature R indicates the paraxial radius of curvature.

The table of [variable spacing data] shows the plane spacing Di to the next plane at the plane number i in which the plane spacing is "variable" in the table showing [lens specifications]. For example, in the first embodiment, the surface spacings D5, D13, D21, and D23 at surface numbers 5, 13, 21, and 23 are shown. These values are shown for each of the wide-angle end state (Wide), intermediate focal length (Middle), and telephoto end state (Tele) in each variable magnification state.

In the table of [Aspherical surface data], the shape of the aspherical surface shown in [Lens specifications] is shown by the following equation (a). X (y) is the distance (zag amount) along the optical axis direction from the tangent plane at the aspherical apex to the position on the aspherical surface at the height y, and R is the radius of curvature of the reference sphere (near axis curvature radius). , Kappa is the conical constant, and Ai is the i-th order aspherical coefficient. "E-n" indicates " ^{x10 -n".} For example, 1.234E-05 = 1.234 × 10 ^-5 . The second-order aspherical coefficient A2 is 0, and the description thereof is omitted.

X (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) )

The [Overall Specifications] table shows the specifications of the entire zoom lens, where f is the focal length of the entire lens system, Fno is the F number, and ω is the half angle of view (maximum angle of view, unit is "° (degrees)". ) Is shown. Bf indicates the distance (back focus) from the final surface of the lens on the optical axis to the image plane I when focusing at infinity, and TL is the total length of the lens, from the frontmost surface of the lens to the final surface of the lens on the optical axis. The distance obtained by adding Bf to the distance is shown. These values are shown for each of the wide-angle end state (Wide), intermediate focal length (Middle), and telephoto end state (Tele) in each variable magnification state.

In the table of [lens group data], the surface number of the group initial surface (the surface closest to the object) in the first to fifth lens groups, the focal length of each group, and the lens configuration length are shown.

The table of [Conditional expression corresponding values] shows the values corresponding to the above conditional expressions (1) to (7).

Hereinafter, in all the specification values, "mm" is generally used for the focal length f, the radius of curvature R, the plane spacing D, other lengths, etc., unless otherwise specified, but the optical system is expanded proportionally. Alternatively, it is not limited to this because the same optical performance can be obtained even if the proportional reduction is performed.

The above is a description of matters common to all the examples, and the duplicated description in each of the following examples will be omitted.

According to the first to fourth embodiments described below, the lens barrel can be retracted into the camera when the camera is not in use while maintaining excellent optical performance, and the lens barrel can be retracted into the camera when the camera is not in use. The lens barrel can be made thinner to achieve a thinner camera. It should be noted that each embodiment shows a specific example of the present invention, and the present invention is not limited thereto.

(First Example)
The first embodiment will be described with reference to FIGS. 1 and 2 and Table 1. FIG. 1 is a diagram showing a lens configuration of the zoom lens ZL (1) according to the first embodiment of the present embodiment. The zoom lens ZL (1) has 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 arranged in order from the object side along the optical axis. It is composed of a third lens group G3 having a force, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 (rear group lens group GR) having a positive refractive power. The code (+) or (-) attached to each lens group symbol indicates the refractive power of each lens group.

An aperture diaphragm S for determining brightness is arranged on the object side of the third lens group G3. The aperture diaphragm S is arranged independently of the third lens group G3, but moves in the optical axis direction together with the third lens group G3. The filter group FL is arranged closer to the image plane I on the image side than the fifth lens group G5. The filter group FL is composed of glass blocks such as a low-pass filter and an infrared cut filter for cutting spatial frequencies above the limit resolution of the solid-state image sensor, such as a CCD arranged on the image plane I.

At the time of scaling, the first to fourth lens groups G1 to G4 move in the axial direction, respectively, as shown by arrows in FIG. Therefore, the surface spacings D5, D13, D21, and D23 are variable, and their values are shown in the [Variable spacing data] table.

The first lens group G1 includes a junction lens of a negative meniscus lens L11 having a concave surface facing the image side and a biconvex positive lens L12 arranged in order from the object side along the optical axis, and a convex surface facing the object side. It is composed of a positive meniscus lens L13.

The second lens group G2 includes a negative meniscus lens L21 having a concave surface facing the image side, a biconcave negative lens L22, and a biconvex positive lens L23 arranged in order from the object side along the optical axis. It is composed of a negative meniscus lens L24 with a concave surface facing the object side. In the negative meniscus lens L21, both the surface on the object side and the surface on the image side are aspherical surfaces.

The third lens group G3 includes a biconvex positive lens L31, a biconvex positive lens L32, and a biconvex negative lens L33, which are arranged in order from the object side along the optical axis, and a biconvex lens. It is composed of a positive lens L34 having a shape. The biconvex positive lens L31 has an aspherical surface on both the object side and the image side.

The fourth lens group G4 is composed of a negative meniscus lens L41 with a concave surface facing the image side.

The fifth lens group G5 is composed of a biconvex positive lens L51. The biconvex positive lens L51 has an aspherical surface on the object side.

In the zoom lens ZL (1), focusing is performed from infinity (long-distance object) to a short-distance object by moving the fourth lens group G4 in the image plane direction. Focusing may be performed using the fifth lens group G5, and further, focusing may be performed using the fourth and fifth lens groups G4 and G5.

In the zoom lens ZL (1), all or at least a part of the third lens group G3 (even if the entire third lens group G3 is used, any one of the lenses L31 to L34 or a combination thereof is used. It is also good) to form a vibration-proof lens group having a displacement component in the direction perpendicular to the optical axis, and image blur correction (vibration-proof, camera shake correction) on the image plane I is performed.

In the zoom lens ZL (1), when the magnification is changed from the wide-angle end state to the telescopic end state, 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 four lens groups change so that the distance between the third lens group G3 and the fourth lens group G4 changes, and the distance between the fourth lens group G4 and the fifth lens group G5 changes. Move G1 to G4. Specifically, as shown by arrows in the figure, each lens group G1 to G4 is moved during the above scaling. At this time, the aperture diaphragm S is integrally moved with the third lens group G3. The fifth lens group G5 is held stationary at the time of scaling.

Table 1 below lists the values of the specifications of the optical system according to the first embodiment.

(Table 1)
[Lens specifications]
Surface number RD nd νd
1 84.081 0.950 1.801 34.922
2 33.297 3.635 1.497 81.729
3 -232.129 0.100
4 34.268 2.703 1.603 65.440
5 308.971 Variable
6 * 351.644 0.500 1.791 44.984
7 * 6.626 3.930
8 -13.076 0.500 1.835 42.733
9 124.029 0.100
10 18.305 2.150 1.923 20.883
11 -20.722 0.420
12 -12.284 0.500 1.786 44.169
13 -209.190 Variable
14 ∞ 0.700 (Aperture S)
15 * 6.418 2.512 1.619 63.854
16 * -26.152 0.100
17 21.083 1.997 1.497 81.729
18 -20.585 0.400 1.881 40.138
19 5.244 0.380
20 6.337 2.185 1.487 70.318
21 -13.197 Variable
22 15.302 0.700 1.497 81.558
23 6.691 Variable
24 * 15.000 2.103 1.531 55.905
25 -30.343 0.600
26 ∞ 0.210 1.517 63.880
27 ∞ 0.450
28 ∞ 0.500 1.517 63.880
29 ∞ 0.400
30 ∞ (image plane I)

[Variable interval data]
Wide Middle Tele
D5 0.700 20.990 40.398
D13 25.959 7.333 1.700
D21 1.922 14.927 13.627
D23 9.890 7.476 13.849

[Aspherical data]
Surface number κ A4 A6 A8 A10
6 1.0000 2.42E-04 -7.54E-06 1.02E-07 -5.96E-10
7 0.6792 3.51E-04 9.75E-08 0.00E + 00 0.00E + 00
15 0.5299 9.62E-06 0.00E + 00 0.00E + 00 0.00E + 00
16 1.0000 3.32E-04 -5.40E-06 0.00E + 00 0.00E + 00
24 -11.1227 5.12E-04 0.00E + 00 0.00E + 00 0.00E + 00

[Overall specifications]
Wide Middle Tele
f 4.230 23.547 139.309
Fno 3.50595 5.49782 7.1755
ω 44.96 9.36 1.62
TL 67.1964 79.4505 98.2998
Bf 0.400 0.400 0.400

[Lens group data]
Group number Group first surface Group focal length G1 1 55.000
G2 6 -5.850
G3 15 11.688
G4 22 -24.580
G5 24 19.209

[Conditional expression correspondence value]
Conditional expression (1) νd1Av / (ft / fw) = 1.843
Conditional expression (2) f4 / f2 = 4.202
Conditional expression (3) f1 / ft = 0.395
Conditional expression (4) (1-β3t) × βRt = 3.743
Conditional expression (5) M3 / M4 = 3.957
Conditional expression (6) ωw = 44.96
Conditional expression (7) ωt = 1.62
However, νd1Av 60.697 The average Abbe number of the 1st group lens
ft / fw (= MagWT) 32.936 Magnification of lens barrel
f1 55.000 1 group focal length
f2 -5.850 Focal length of 2 groups
f4 -24.580 Focal length of 4 groups
ft 139.309 Focal length of the entire zoom lens at the telephoto end
(1-β3t) × βRt (= VRt3) 3.743 Three-group blur sensitivity coefficient at the telephoto end
M3 15.664 Amount of movement in 3 groups from wide-angle end to telephoto end
M4 3.959 4 group movement amount from wide-angle end to telephoto end (Movement amount M3 and M4 are positive movement to the object side. The same applies to the following examples.)

As shown in the table of the above [conditional expression corresponding values], the zoom lens ZL (1) according to the first embodiment shown in FIG. 1 satisfies all of the above conditional expressions (1) to (7).

2 (a), 2 (b) and 2 (c) show infinity focusing in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the zoom lens ZL (1) according to the first embodiment, respectively. It is a various aberration diagram (spherical aberration diagram, astigmatism diagram, distortion diagram, coma aberration diagram, and chromatic aberration of magnification diagram) of time. As can be seen from the various aberration diagrams, the zoom lens ZL (1) according to the first embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state, and has excellent imaging performance. There is. Distortion can be corrected by image processing after imaging, and optical correction is not required.

In FIG. 2, FNO indicates an F number, and ω indicates a half angle of view (unit: “°”) for each image height. d indicates the aberration in the d line (wavelength 587.6 nm), g indicates the aberration in the g line (wavelength 435.8 nm), C indicates the aberration in the C line (wavelength 656.3 nm), and F indicates the aberration in the F line (wavelength 486.1 nm). In the spherical aberration diagram, the astigmatism diagram, and the coma aberration diagram, the solid line indicates the aberration of the sagittal image plane, and the broken line indicates the aberration of the meridional image plane. This description is the same for all the aberration diagrams of each of the following examples, and the duplicated description below will be omitted.

(Second Example)
The second embodiment will be described with reference to FIGS. 3 and 4 and Table 2. FIG. 3 is a diagram showing a lens configuration of the zoom lens ZL (2) according to the second embodiment of the present embodiment. The zoom lens ZL (2) has 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 arranged in order from the object side along the optical axis. It is composed of a third lens group G3 having a force, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 (rear group lens group GR) having a positive refractive power. The aperture diaphragm S is arranged on the object side of the third lens group G3 and moves in the optical axis direction together with the third lens group G3. A filter group FL is arranged between the fifth lens group G5 and the image plane I.

At the time of scaling, the first to fourth lens groups G1 to G4 move in the axial direction, respectively, as shown by arrows in FIG. Therefore, the surface spacings D5, D13, D21, and D23 are variable, and their values are shown in the [Variable spacing data] table.

The first lens group G1 includes a junction lens of a negative meniscus lens L11 having a concave surface facing the image side and a biconvex positive lens L12 arranged in order from the object side along the optical axis, and a convex surface facing the object side. It is composed of a positive meniscus lens L13.

The second lens group G2 includes a negative meniscus lens L21 having a concave surface facing the image side, a biconcave negative lens L22, and a biconvex positive lens L23 arranged in order from the object side along the optical axis. It is composed of a negative meniscus lens L24 with a concave surface facing the object side.

The third lens group G3 includes a biconvex positive lens L31 arranged in order from the object side along the optical axis, a positive meniscus lens L32 with a convex surface facing the object side, and a negative meniscus lens L32 with a concave surface facing the image side. It is composed of a bonded lens of L33 and a biconvex positive lens L34. The biconvex positive lens L31 has an aspherical surface on both the object side and the image side.

The fourth lens group G4 is composed of a negative meniscus lens L41 with a concave surface facing the image side.

The fifth lens group G5 is composed of a biconvex positive lens L51. The biconvex positive lens L51 has an aspherical surface on the object side.

In the zoom lens ZL (2), focusing is performed from infinity (long-distance object) to a short-distance object by moving the fourth lens group G4 in the image plane direction. Focusing may be performed using the fifth lens group G5, and further, focusing may be performed using the fourth and fifth lens groups G4 and G5.

In the zoom lens ZL (2), all or at least a part of the third lens group G3 constitutes an anti-vibration lens group having a displacement component in a direction perpendicular to the optical axis, and image stabilization (prevention) on the image plane I. Shake and camera shake correction).

In the zoom lens ZL (2), the four lens groups G1 to G4 are moved as shown by arrows in the figure. At this time, the aperture diaphragm S is integrally moved with the third lens group G3. The fifth lens group G5 is held stationary at the time of scaling.

Table 2 below lists the values of the specifications of the optical system according to the second embodiment.

(Table 2)
[Lens specifications]
Surface number RD nd νd
1 100.769 0.950 1.801 34.922
2 35.364 3.700 1.497 81.729
3 -157.214 0.100
4 35.936 2.600 1.603 65.440
5 464.361 Variable
6 142.278 0.500 1.773 49.619
7 6.625 3.500
8 -13.778 0.550 1.850 32.352
9 52.636 0.100
10 15.649 2.550 1.923 20.880
11 -15.649 0.456
12 -11.089 0.550 1.834 37.183
13 -19904.544 Variable
14 ∞ 0.700 (Aperture S)
15 * 7.439 2.200 1.497 81.558
16 * -25.999 0.100
17 7.999 2.200 1.517 52.203
18 67.195 0.400 1.911 35.249
19 6.199 0.800
20 17.204 1.650 1.497 81.729
21 -17.204 Variable
22 12.947 0.600 1.497 81.729
23 6.243 Variable
24 * 13.300 2.200 1.531 56.138
25 -81.348 0.600
26 ∞ 0.210 1.517 63.880
27 ∞ 0.450
28 ∞ 0.500 1.517 63.880
29 ∞ 0.400
30 ∞ (image plane I)

[Variable interval data]
Wide Middle Tele
D5 0.700 21.699 40.629
D13 26.500 7.485 1.700
D21 3.062 17.414 14.453
D23 8.772 5.391 14.489

[Aspherical data]
Surface number κ A4 A6 A8 A10
15 0.5354 -8.82E-05 0.00E + 00 0.00E + 00 0.00E + 00
16 1.0000 1.68E-04 -1.05E-06 0.00E + 00 0.00E + 00
24 5.0990 3.17E-05 0.00E + 00 0.00E + 00 0.00E + 00

[Overall specifications]
Wide Middle Tele
f 4.430 24.62 145.505
Fno 3.53248 5.50955 7.19932
ω 43.64 8.95 1.57
TL 67.6000 80.5542 99.8367
Bf 0.400 0.400 0.400

[Lens group data]
Group number Group first surface Group focal length G1 1 55.500
G2 6 -6.200
G3 15 12.066
G4 22 -25.000
G5 24 21.698

[Conditional expression correspondence value]
Conditional expression (1) νd1Av / (ft / fw) = 1.848
Conditional expression (2) f4 / f2 = 4.032
Conditional expression (3) f1 / ft = 0.381
Conditional expression (4) (1-β3t) × βRt = 3.803
Conditional expression (5) M3 / M4 = 2.993
Conditional expression (6) ωw = 43.64
Conditional expression (7) ωt = 1.57
However, νd1Av 60.697
ft / fw 32.845
f1 55.500
f2 -6.200
f4 -25.000
ft 145.505
(1-β3t) × βRt 3.803
M3 17.108
M4 5.716

As shown in the table of the above [conditional expression corresponding values], the zoom lens ZL (2) according to the second embodiment shown in FIG. 3 satisfies all of the above conditional expressions (1) to (7).

4 (a), 4 (b) and 4 (c) show infinity focusing in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the zoom lens ZL (2) according to the second embodiment, respectively. It is a various aberration diagram (spherical aberration diagram, astigmatism diagram, distortion diagram, coma aberration diagram, and chromatic aberration of magnification diagram) of time. As can be seen from the various aberration diagrams, the zoom lens ZL (2) according to the second embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state, and has excellent imaging performance. There is.

(Third Example)
The third embodiment will be described with reference to FIGS. 5 and 6 and Table 3. FIG. 5 is a diagram showing a lens configuration of the zoom lens ZL (3) according to the third embodiment of the present embodiment. The zoom lens ZL (3) has 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 arranged in order from the object side along the optical axis. It is composed of a third lens group G3 having a force, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 (rear group lens group GR) having a positive refractive power. The aperture diaphragm S is arranged on the object side of the third lens group G3 and moves in the optical axis direction together with the third lens group G3. A filter group FL is arranged between the fifth lens group G5 and the image plane I.

At the time of scaling, the first to fourth lens groups G1 to G4 move in the axial direction, respectively, as shown by arrows in FIG. Therefore, the surface spacings D5, D13, D21, and D23 are variable, and their values are shown in the [Variable spacing data] table.

The first lens group G1 includes a junction lens of a negative meniscus lens L11 having a concave surface facing the image side and a biconvex positive lens L12 arranged in order from the object side along the optical axis, and a convex surface facing the object side. It is composed of a positive meniscus lens L13.

The second lens group G2 includes a negative meniscus lens L21 having a concave surface facing the image side, a biconcave negative lens L22, and a biconvex positive lens L23 arranged in order from the object side along the optical axis. It is composed of a biconcave negative lens L24. The negative meniscus lens L21 has an aspherical surface on the object side.

The third lens group G3 includes a biconvex positive lens L31, a biconvex positive lens L32, and a biconvex negative lens L33, which are arranged in order from the object side along the optical axis, and a biconvex lens. It is composed of a positive lens L34 having a shape. The biconvex positive lens L31 has an aspherical surface on both the object side and the image side.

The fourth lens group G4 is composed of a negative meniscus lens L41 with a concave surface facing the image side.

The fifth lens group G5 is composed of a biconvex positive lens L51. The biconvex positive lens L51 has an aspherical surface on the object side.

In the zoom lens ZL (3), focusing is performed from infinity (long-distance object) to a short-distance object by moving the fourth lens group G4 in the image plane direction. Focusing may be performed using the fifth lens group G5, and further, focusing may be performed using the fourth and fifth lens groups G4 and G5.

In the zoom lens ZL (3), all or at least a part of the third lens group G3 constitutes an anti-vibration lens group having a displacement component in a direction perpendicular to the optical axis, and image stabilization (prevention) on the image plane I. Shake and camera shake correction).

In the zoom lens ZL (3), the four lens groups G1 to G4 are moved as shown by arrows in the figure. At this time, the aperture diaphragm S is integrally moved with the third lens group G3. The fifth lens group G5 is held stationary at the time of scaling.

Table 3 below lists the values of the specifications of the optical system according to the third embodiment.

(Table 3)
[Lens specifications]
Surface number RD nd νd
1 75.680 0.950 1.850 32.352
2 34.368 3.900 1.497 81.729
3-200.301 0.100
4 34.679 2.950 1.589 61.219
5 348.366 Variable
6 * 166.354 0.557 1.851 40.104
7 6.347 3.550
8 -13.756 0.562 1.741 52.765
9 64.108 0.100
10 15.386 2.017 1.923 20.880
11 -29.910 0.350
12 -16.800 0.600 1.835 42.733
13 285.381 Variable
14 ∞ 0.600 (Aperture S)
15 * 6.988 2.318 1.589 61.250
16 * -27.897 0.307
17 13.734 1.718 1.497 81.729
18 -19.677 0.554 1.881 40.138
19 6.602 0.229
20 10.163 1.990 1.497 81.729
21 -12.964 Variable
22 14.274 0.861 1.497 81.729
23 6.157 Variable
24 * 12.935 1.850 1.531 56.138
25 -56.448 0.600
26 ∞ 0.210 1.517 63.880
27 ∞ 0.450
28 ∞ 0.500 1.517 63.880
29 ∞ 0.400
30 ∞ (image plane I)

[Variable interval data]
Wide Middle Tele
D5 0.700 20.800 39.500
D13 25.138 7.262 1.580
D21 3.068 15.898 12.398
D23 9.003 6.895 14.026

[Aspherical data]
Surface number κ A4 A6 A8 A10
6 1.0000 5.47E-06 -5.12E-07 4.17E-09 -6.61E-11
15 0.6989 -1.13E-04 8.67E-07 0.00E + 00 0.00E + 00
16 1.0000 2.00E-04 -3.48E-07 0.00E + 00 0.00E + 00
24 0.5521 1.51E-04 9.50E-06 1.16E-07 0.00E + 00

[Overall specifications]
Wide Middle Tele
f 4.430 24.628 145.505
Fno 3.53248 5.50955 7.19932
ω 43.79 8.93 1.55
TL 67.6000 80.5542 99.8367
Bf 0.400 0.400 0.400

[Lens group data]
Group number Group first surface Group focal length G1 1 53.468
G2 6 -5.868
G3 15 11.675
G4 22 -22.580
G5 24 19.999

[Conditional expression correspondence value]
Conditional expression (1) νd1Av / (ft / fw) = 1.769
Conditional expression (2) f4 / f2 = 3.848
Conditional expression (3) f1 / ft = 0.365
Conditional expression (4) (1-β3t) × βRt = 3.649
Conditional expression (5) M3 / M4 = 2.858
Conditional expression (6) ωw = 43.79
Conditional expression (7) ωt = 1.55
However, νd1Av 58.433
ft / fw 33.026
f1 53.468
f2 -5.868
f4 -22.580
ft 146.340
(1-β3t) × βRt 3.649
M3 14.353
M4 5.023

As shown in the table of the above [conditional expression corresponding values], the zoom lens ZL (3) according to the third embodiment shown in FIG. 5 satisfies all of the above conditional expressions (1) to (7).

6 (a), 6 (b) and 6 (c) show infinity focusing in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the zoom lens ZL (3) according to the third embodiment, respectively. It is a various aberration diagram (spherical aberration diagram, astigmatism diagram, distortion diagram, coma aberration diagram, and chromatic aberration of magnification diagram) of time. As can be seen from the various aberration diagrams, the zoom lens ZL (3) according to the third embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state, and has excellent imaging performance. There is.

(Fourth Example)
The fourth embodiment will be described with reference to FIGS. 7 and 8 and Table 4. FIG. 7 is a diagram showing a lens configuration of the zoom lens ZL (4) according to the fourth embodiment of the present embodiment. The zoom lens ZL (4) has 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 arranged in order from the object side along the optical axis. It is composed of a third lens group G3 having a force, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 (rear group lens group GR) having a positive refractive power. The aperture diaphragm S is arranged on the object side of the third lens group G3 and moves in the optical axis direction together with the third lens group G3. A filter group FL is arranged between the fifth lens group G5 and the image plane I.

At the time of scaling, the first to fourth lens groups G1 to G4 move in the axial direction, respectively, as shown by arrows in FIG. Therefore, the surface spacings D5, D13, D21, and D23 are variable, and their values are shown in the [Variable spacing data] table.

The first lens group G1 includes a junction lens of a negative meniscus lens L11 having a concave surface facing the image side and a biconvex positive lens L12 arranged in order from the object side along the optical axis, and a convex surface facing the object side. It is composed of a positive meniscus lens L13.

The second lens group G2 includes a negative meniscus lens L21 having a concave surface facing the image side, a biconcave negative lens L22, and a biconvex positive lens L23 arranged in order from the object side along the optical axis. It is composed of a biconcave negative lens L24. The negative meniscus lens L21 has an aspherical surface on both the side surface of the object and the side surface of the image.

The third lens group G3 is a biconvex positive lens L31 arranged in order from the object side along the optical axis.
It is composed of a junction lens of a biconvex positive lens L32 and a biconcave negative lens L33, and a biconvex positive lens L34. The biconvex positive lens L31 has an aspherical surface on both the object side and the image side.

The fourth lens group G4 is composed of a negative meniscus lens L41 with a concave surface facing the image side.

The fifth lens group G5 is composed of a biconvex positive lens L51. The biconvex positive lens L51 has an aspherical surface on the object side.

In the zoom lens ZL (4), focusing from infinity (long-distance object) to a short-distance object is performed by moving the fourth lens group G4 in the image plane direction. Focusing may be performed using the fifth lens group G5, and further, focusing may be performed using the fourth and fifth lens groups G4 and G5.

In the zoom lens ZL (4), all or at least a part of the third lens group G3 constitutes an anti-vibration lens group having a displacement component in a direction perpendicular to the optical axis, and image stabilization (prevention) on the image plane I. Shake and camera shake correction).

In the zoom lens ZL (4), the four lens groups G1 to G4 are moved as shown by arrows in the figure. At this time, the aperture diaphragm S is integrally moved with the third lens group G3. The fifth lens group G5 is held stationary at the time of scaling.

Table 4 below lists the values of the specifications of the optical system according to the fourth embodiment.

(Table 4)
[Lens specifications]
Surface number RD nd νd
1 74.440 0.950 1.850 32.352
2 35.259 3.650 1.497 81.729
3 -245.979 0.100
4 35.839 2.732 1.603 65.440
5 273.702 Variable
6 * 66.947 0.600 1.791 44.984
7 * 5.877 3.500
8 -16.856 0.500 1.835 42.733
9 75.894 0.100
10 13.917 2.350 1.923 20.883
11 -34.608 0.527
12 -13.472 0.500 1.744 44.803
13 150.000 variable
14 ∞ 0.700 (Aperture S)
15 * 6.976 2.452 1.619 63.854
16 * -29.782 0.100
17 14.837 1.984 1.497 81.729
18 -23.014 0.400 1.881 40.138
19 6.393 0.380
20 10.402 1.950 1.497 81.729
21 -13.933 Variable
22 14.917 0.700 1.497 81.558
23 6.674 Variable
24 * 14.393 2.268 1.531 56.138
25 -31.025 0.732
26 ∞ 0.210 1.517 63.880
27 ∞ 0.450
28 ∞ 0.500 1.517 63.880
29 ∞ 0.400
30 ∞ (image plane I)

[Variable interval data]
Wide Middle Tele
D5 0.700 21.236 40.322
D13 25.663 7.582 1.700
D21 2.441 15.576 14.676
D23 9.617 7.469 14.327

[Aspherical data]
Surface number κ A4 A6 A8 A10
6 1.0000 5.48E-05 -5.82E-06 1.02E-07 -6.72E-10
7 0.4812 3.09E-04 -1.44E-06 0.00E + 00 0.00E + 00
15 0.3196 3.54E-05 0.00E + 00 0.00E + 00 0.00E + 00
16 1.0000 2.06E-04 -3.00E-06 0.00E + 00 0.00E + 00
24 5.4724 -2.36E-05 0.00E + 00 0.00E + 00 0.00E + 00

[Overall specifications]
Wide Middle Tele
f 4.430 24.635 145.609
Fno 3.5278 5.655 7.14372
ω 43.19 8.99 1.57
TL 67.1574 80.5986 99.7598
Bf 0.400 0.400 0.400

[Lens group data]
Group number Group first surface Group focal length G1 1 55.500
G2 6 -6.000
G3 15 11.814
G4 22 -25.000
G5 24 18.838

[Conditional expression correspondence value]
Conditional expression (1) νd1Av / (ft / fw) = 1.821
Conditional expression (2) f4 / f2 = 4.167
Conditional expression (3) f1 / ft = 0.381
Conditional expression (4) (1-β3t) × βRt = 3.826
Conditional expression (5) M3 / M4 = 3.598
Conditional expression (6) ωw = 43.19
Conditional expression (7) ωt = 1.57
However, νd1Av 59.841
ft / fw 32.867
f1 55.500
f2 -6.000
f4 -25.000
ft 145.609
(1-β3t) × βRt 3.826
M3 16.944
M4 4.710

As shown in the table of the above [conditional expression corresponding values], the zoom lens ZL (4) according to the fourth embodiment shown in FIG. 7 satisfies all of the above conditional expressions (1) to (7).

8 (a), 8 (b) and 8 (c) show infinity focusing in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the zoom lens ZL (4) according to the fourth embodiment, respectively. It is a various aberration diagram (spherical aberration diagram, astigmatism diagram, distortion diagram, coma aberration diagram, and chromatic aberration of magnification diagram) of time. As can be seen from the various aberration diagrams, the zoom lens ZL (4) according to the fourth embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state, and has excellent imaging performance. There is.

Each of the above examples shows a specific example of the present invention, and the present invention is not limited thereto.

The following contents can be appropriately adopted as long as the optical performance of the zoom lens of the present embodiment is not impaired.

As an example of the zoom lens of the present embodiment, a zoom lens having a 5-group configuration is shown, but the present application is not limited to this, and a zoom lens having another group configuration (for example, 6 groups, etc.) can also be configured. In particular, the present invention has a configuration in which a rear lens group GR composed of at least one lens group is provided on the image plane side of the fourth lens group, and the rear lens group is from the fifth lens group as shown in the above embodiment. In addition to the fifth lens group, a sixth lens group or more lens groups may be provided. Further, a lens or a lens group may be added to the most object side or the most image plane side of the zoom lens of the present embodiment. The lens group refers to a portion having at least one lens separated by an air interval that changes at the time of magnification change.

A single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to focus on a short-range object from an infinity object. The focusing lens group can also be applied to autofocus, and is also suitable for driving a motor for autofocus (using an ultrasonic motor or the like).

The lens group or partial lens group is moved so as to have a component in the direction perpendicular to the optical axis, or rotationally moved (oscillated) in the in-plane direction including the optical axis to correct image blur caused by camera shake. It may be used as an anti-vibration lens group.

The lens surface may be formed on a spherical surface or a flat surface, or may be formed on an aspherical surface. When the lens surface is spherical or flat, lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to processing and assembly adjustment errors can be prevented, which is preferable. Further, even if the image plane is deviated, the depiction performance is less deteriorated, which is preferable.

When the lens surface is aspherical, the aspherical surface is an aspherical surface formed by grinding, a glass mold aspherical surface formed by forming glass into an aspherical shape, or a composite aspherical surface formed by forming resin on the glass surface into an aspherical shape. It doesn't matter which one. Further, the lens surface may be a diffraction surface, and the lens may be a refractive index distribution type lens (GRIN lens) or a plastic lens.

The aperture diaphragm is preferably arranged near or in the third lens group, but the role may be substituted by the frame of the lens without providing the member as the aperture diaphragm.

An antireflection film having a high transmittance in a wide wavelength range may be applied to each lens surface in order to reduce flare and ghost and achieve high contrast optical performance.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group GR rear group lens group FL filter group I image plane S aperture aperture

Claims (8)

A first lens group having a positive refractive index, a second lens group having a negative refractive index, a third lens group having a positive refractive index, and a negative lens group arranged in order from the object side along the optical axis. It consists of substantially five lens groups, a fourth lens group having a refractive index and a fifth lens group having a positive refractive power.
The first lens group has three or more lenses.
When the magnification is changed from the wide-angle end state to the telephoto end state, the distance between adjacent lens groups changes,
The fifth lens group is fixedly held at the time of variable magnification, and is fixedly held.
A zoom lens characterized by satisfying the following conditional expression.
1.750 <νd1Av / (ft / fw) <1.900
2.800 <M3 / M4 <4.10
However, νd1Av: the average Abbe number of the d-line of the lens in the first lens group fw: the focal length of the entire zoom lens at the wide-angle end ft: the focal length of the entire zoom lens at the telephoto end M3: the third lens Amount of movement from the wide-angle end to the telephoto end of the group M4: Amount of movement from the wide-angle end to the telephoto end of the fourth lens group (each movement amount is positive for movement toward the object side) The zoom lens according to claim 1 , wherein the zoom lens satisfies the following conditional expression.
0.360 <f1 / ft <0.400
However, f1: the focal length of the first lens group The zoom lens according to claim 1 or 2 , wherein the zoom lens satisfies the following conditional expression.
15.0 <ωw <65.0
However, ωw: Half angle of view of the entire zoom lens at the wide-angle end (unit: degree) The zoom lens according to any one of claims 1 to 3 , wherein the zoom lens satisfies the following conditional expression.
0.5 <ωt <7.0
However, ωt: Half angle of view of the entire zoom lens at the telephoto end (unit: degree) The zoom lens according to any one of claims 1 to 4 , wherein the third lens group has at least one aspherical lens. The zoom lens according to any one of claims 1 to 5 , wherein at least a part of the fourth lens group is a focusing lens. The zoom lens according to any one of claims 1 to 6 , wherein at least a part of the third lens group has a displacement component in the direction perpendicular to the optical axis. An optical device including the zoom lens according to any one of claims 1 to 7.

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