JP5433942B2 - Zoom lens, optical apparatus including the same, and imaging method - Google Patents

Description

  The present invention relates to a zoom lens suitable for an electronic still camera and the like, an optical apparatus equipped with the zoom lens, and an imaging method.

  Conventionally, 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 first lens group having a positive refractive power. A zoom lens having a four-group configuration having four lens groups has been proposed (see, for example, Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 4-171411 JP 2005-62228 A

  However, the zoom lens of the above-mentioned patent document has a problem that the illumination light is vignetted due to the object side structure of the lens barrel at the time of flash photography at the wide-angle end because the total lens length is long with respect to the focal length at the wide-angle end. there were.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a small zoom lens having excellent optical performance, an optical apparatus equipped with the zoom lens, and an imaging method.

In order to achieve such an object, the zoom lens of the present invention includes a first lens group having a positive refractive power and a second lens group having a negative refractive power, which are arranged in order from the object side along the optical axis. And a third lens group having a positive refractive power and a fourth lens group having a positive refractive power, substantially consisting of four lens groups, and from the wide-angle end state to the telephoto end state in the infinite focus state The first lens group and the third lens group are moved to the object side, the second lens group is moved along the optical axis along a concave locus on the object side, The four lens groups are moved along the optical axis along a locus convex toward the object side, and the third lens group is arranged in order from the object side, a positive lens L31, a negative meniscus lens L32 having a convex surface facing the object side, A front lens group G3F having a positive lens L33 and having a positive refractive power, and convex toward the object side The negative meniscus lens L34 facing the lens, and any one of the three surfaces of the object side and image side lens surfaces of the positive lens L31 and the object side lens surface of the negative meniscus lens L32 is an aspherical surface. In addition, any one of the three surfaces of the image side lens surface of the positive lens L33 and the object side and image side lens surfaces of the negative meniscus lens L34 is an aspherical surface, and the focal length of the third lens group is determined. If f30 is set, and the focal length of the negative meniscus lens L34 is f34, the following condition −0.6 <f30 / f34 <−0.1 is satisfied.

  The radius of curvature of the image side lens surface of the negative meniscus lens L32 and the radius of curvature of the object side lens surface of the positive lens L33 are smaller than those of the other lens surfaces constituting the third lens group. Is preferred.

  In the third lens group, it is preferable that the negative meniscus lens L32 and the positive lens L33 are bonded to form a cemented lens.

  When the focal length of the front lens group in the third lens group is fG3F, the focal length of the negative meniscus lens L34 is f34, and the average refractive index N3n of the negative meniscus lens L32 and the negative meniscus lens L34 is set. It is preferable that the following formula −0.24 <fG3F / (f34 × N3n) <− 0.05 is satisfied.

Further, when the wide-angle end focal length of the entire lens system is Fw, the focal length of the third lens group is f30, and the telephoto end focal length of the entire lens system is Ft, 0.03 <(Fw × f30) ) / Ft ² <0.08 is preferably satisfied.

  Further, when the thickness on the optical axis of the positive lens L33 is d33 and the thickness on the optical axis of the third lens group is d30, the condition of the following expression 0.28 <d33 / d30 <0.60 Is preferably satisfied.

  Further, it is preferable to perform image blur correction by moving the front group of the third lens group in a direction perpendicular to the optical axis.

  In the third lens group, it is preferable to arrange a flare cut stop between the image side lens surface of the positive lens L33 and the object side lens surface of the negative meniscus lens L34.

  Further, it is preferable to perform image blur correction by moving the second lens group in a direction perpendicular to the optical axis.

  Further, it is preferable that a flare cut stop is disposed on each of the object side and the image side of the second lens group.

  The fourth lens group is preferably composed of a positive meniscus lens having a convex surface directed toward the object side, and the photographing object is preferably moved toward the object side along the optical axis when focused at a finite distance.

  Moreover, the optical apparatus of the present invention is equipped with the zoom lens.

The imaging method of the present invention has a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power, which are arranged in order from the object side along the optical axis. Image formation in which an image of the object is formed on a predetermined image plane by using a zoom lens that is substantially composed of four lens groups by a third lens group and a fourth lens group having a positive refractive power. In the method, when zooming from the wide-angle end state to the telephoto end state in the infinite focus state, the first lens group and the third lens group are moved to the object side, and the second lens group is moved The fourth lens group is moved along the optical axis along a convex trajectory on the object side, and the third lens group is arranged in order from the object side. However, a positive lens L31, a negative meniscus lens L32 having a convex surface facing the object side, and a positive lens L33 are provided. And a negative meniscus lens L34 having a convex surface facing the object side, an object side and image side lens surface of the positive lens L31, and an object side lens surface of the negative meniscus lens L32. Any one of the three surfaces is an aspheric surface, and one of the three surfaces of the image side lens surface of the positive lens L33 and the object side and image side lens surfaces of the negative meniscus lens L34. Is an aspherical surface, the focal length of the third lens unit is f30, and the focal length of the negative meniscus lens L34 is f34, the following equation −0.6 <f30 / f34 <−0.1 is satisfied. It is characterized by that.

  As described above, according to the present invention, it is possible to provide a small zoom lens having excellent optical performance, an optical apparatus equipped with the zoom lens, and an imaging method.

  Hereinafter, preferred embodiments will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a digital single-lens reflex camera 1 (optical apparatus) including a zoom lens ZL according to this embodiment. In the digital single-lens reflex camera 1 shown in FIG. 1, light from an object (subject) (not shown) is collected by the taking lens 2 and is focused on the light collecting plate 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. The camera 1 shown in FIG. 1 may hold the zoom lens ZL so as to be detachable, 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 that does not have a quick return mirror or the like.

  By the way, the zoom lens ZL according to the present embodiment used as the photographing lens 2 of the digital single-lens reflex camera 1 includes a first lens group G1 having a positive refractive power and arranged in order from the object side along the optical axis. The second lens group G2 having negative refractive power, the third lens group G3 having positive refractive power, and the fourth lens group G4 having positive refractive power.

  To explain the above lens configuration from an optical point of view, the first lens group G1 is a condenser lens group, the second lens group G2 is a variable power lens group, the third lens group G3 is an imaging lens group, and the fourth lens group G4. Is a field lens group.

  In the zoom lens ZL having the above-described configuration, the first lens group G1 and the second lens group G2 have a large change in light incident height and light incident angle with zooming (magnification). Greatly related to fluctuations in

  Therefore, the first lens group G1 has a negative meniscus lens L11 having a convex surface facing the object side and a positive lens L12 arranged in order from the object side, and is configured in a concentric shape with respect to the aperture stop. Therefore, it is possible to suppress the variation in field curvature due to zooming. Furthermore, in the first lens group G1, if the negative meniscus lens L11 and the positive lens L12 are cemented lenses, mutual decentration does not occur when the lens is assembled into the lens barrel. This is preferable because it can prevent the phenomenon of tilting).

  The second lens group G2 includes a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, and a positive lens L23 arranged in order from the object side. The negative meniscus lens L21 is an object side lens. By making the surface an aspherical surface and the positive lens L23 having either one of the object-side and image-side lens surfaces as an aspherical surface, it is possible to suppress variations in spherical aberration due to zooming. Further, in the second lens group G2, the negative meniscus lens L21, the biconcave lens L22, and the positive lens L23 are all composed of a single lens (in other words, all of these lenses are sandwiched with air), and aberrations are achieved. It is preferable to ensure the degree of freedom of correction.

  In order to further shorten the overall lens length in the wide-angle end state, the first lens group G1 is composed of two concave / convex lenses, and the second lens group G2 is composed of three concave / convex lenses. It is preferable to reduce the total glass thickness of the group G1 and the second lens group G2.

  The third lens group G3 has little change in light incident height and light incident angle during zooming (magnification), and therefore contributes little to various aberration fluctuations during zooming. However, the third lens group G3 is an imaging lens group as described above, and the light beam condensed by the first lens group G1 is further condensed to form an image. The lens configuration has a small radius. Therefore, in the third lens group G3, high-order spherical aberration tends to occur greatly. Therefore, it is preferable to arrange an aperture stop on the third lens group G3 (on the object side) so that incident light enters at a gentle angle to suppress the occurrence of spherical aberration.

  Here, the third lens group G3 includes a positive lens L31, a negative meniscus lens L32 having a convex surface directed toward the object side, and a positive lens L33, which are arranged in order from the object side along the optical axis, and has a positive refractive power. It is preferable to adopt a so-called telephoto type lens configuration including the front group G3F and a negative meniscus lens L34 having a convex surface facing the object side. With this configuration, the back focus of the third lens group G3 is shortened, that is, the back focus of the entire lens system is shortened. Furthermore, since the incident light beam height of the first lens group G1 with respect to the maximum photographing field angle is reduced, the effective diameter of the first lens group G1 is reduced, and the total lens length at the wide angle end is also reduced.

  In addition, the third lens group G3 can adjust the Seidel 5 aberration correction by making the front group G3F a positive / negative / positive triplet structure, and a negative lens (negative meniscus lens L32) is added to the front group G3F of the triplet structure. ) Is preferable in terms of aberration correction because aberrations of field curvature can be corrected. Further, in order to more favorably correct the aberration of the front group G3F having the triplet structure, the curvature radius of the image side lens surface of the negative meniscus lens L32 and the curvature radius of the object side lens surface of the positive lens L33 are set to a third value. It is preferable to make it smaller than the radius of curvature of the other lens surfaces constituting the lens group G3. This is because the image side lens surface of the negative meniscus lens L32 and the object side lens surface of the positive lens L33 facing each other are lens surfaces whose exit angles with respect to the incident light bundle are gentle regardless of the angle of view. Even if these are used as a strong negative refracting surface and a strong positive refracting surface, high-order spherical aberration hardly occurs. Therefore, by configuring the front group G3F with the above-described configuration, it is possible to simultaneously correct spherical aberration and chromatic aberration caused by the front group G3F having positive refractive power. In order to correct chromatic aberration more favorably in the front group G3F, it is preferable to join the image side lens surface of the negative meniscus lens L32 and the object side lens surface of the positive lens L33 with the same radius of curvature.

Further, in the third lens group G3 having the above-described configuration, in order to correct aberrations more favorably, three surfaces of the object side and image side lens surfaces of the positive lens L31 and the object side lens surface of the negative meniscus lens L32 are used. Any one of the surfaces is an aspheric surface ASP1, and any one of the three surfaces of the image side lens surface of the positive lens L33 and the object side and image side lens surfaces of the negative meniscus lens L34 is an aspheric surface ASP2. It is preferable to do. The former aspherical surface ASP1 corrects spherical aberration and coma, and the latter aspherical surface ASP2 corrects field curvature aberration at the wide-angle end.

  Since the fourth lens group G4 has a small incident beam diameter with respect to each image height, the fourth lens group G4 is more greatly affected by fluctuations in field curvature than spherical aberration. Therefore, it is preferable that the fourth lens group G4 includes a positive lens whose object side lens surface is convex on the object side. Thereby, the aberration fluctuation | variation of the curvature of field in short distance focusing can be suppressed. Further, it is preferable to move the fourth lens group G4 to the object side along the optical axis when focusing from an object at infinity to an object at a short distance. Thereby, the fluctuation | variation of the spherical aberration in near distance focusing can be reduced. The fourth lens group G4 also has an action of suppressing shading by separating the exit pupil position from the imaging plane (to the object side) when matching between the solid-state imaging device and the imaging optical system. .

  In order to shorten the overall length of the zoom lens ZL when the lens barrel is housed even though it is a high variable magnification optical system, zooming from the wide-angle end state to the telephoto end state at infinity (zooming) At this time, it is preferable to move the first lens group G1 to the object side. Thereby, in the 1st lens group G1, the full length at the time of accommodation smaller than the full length lens of a wide angle end state can be achieved by a simple method. Further, in order to perform effective zooming, during zooming, the second lens group G2 is moved along the optical axis along a concave locus on the object side, and the third lens group G3 is moved to the object side. It is preferable. With this configuration, the space necessary for zooming in the second lens group G2 can be reduced, and the space necessary for zooming in the third lens group G3 can be secured. The fourth lens group G4 is preferably moved along the optical axis along a locus convex toward the object side. With this configuration, it is possible to correct a variation in field curvature due to zooming.

  In the zoom lens ZL, as described above, the front lens group G3F of the third lens group G3 has a positive and negative triplet structure, so that Seidel 5 aberration correction can be adjusted. Accordingly, if the front lens group G3F is configured so that the constituent lenses are integrated and moved in a direction perpendicular to the optical axis to perform image stabilization correction, sufficient aberration correction can be performed. Furthermore, by disposing a negative meniscus lens L34 on the image side of the front group G3F and appropriately defining the refractive power distribution between the front group G3F and the negative meniscus lens L34, the movement of the imaging plane with respect to the movement amount of the front group G3F The amount can be adjusted and is effective.

  Here, if the image side lens surface of the positive lens L33 is an aspherical surface in the front group G3F, the third lens group G3 becomes a lens group having imaging performance more suitable for image stabilization. Further, the effective diameter of the front group G3F is larger than that in the case of non-vibration stabilization when the image stabilization correction is performed in the third lens group G3 as described above in order to take into account the amount of vibration-proof movement. Therefore, in order to cut a portion having a large coma aberration, it is preferable to dispose a flare cut stop between the image side lens surface of the positive lens L33 and the object side lens surface of the negative meniscus lens L34 in the third lens group G3. . At this time, the flare cut stop may be integrated with a lens barrel that fixes the negative meniscus lens L34. In the present embodiment, the flare cut stop also has an effect as a field stop.

  Further, since the second lens group G2 is a lens group having a large degree of freedom of aberration correction like the third lens group G3, the second lens group G2 is moved in the direction perpendicular to the optical axis as a unit. Thus, image blur correction may be performed. When performing image stabilization correction in the second lens group G2, the amount of image stabilization movement must be taken into account in the same manner as described above, and therefore the effective diameter of the second lens group G2 is larger than that during non-image stabilization. Therefore, in order to cut a portion having a large coma aberration, it is preferable to arrange flare cut stops on the object side and the image side of the second lens group G2.

  In the zoom lens ZL configured as described above, in order to perform good aberration correction while keeping the effective diameter of the first lens group G1 small, the focal length of the third lens group G3 is set to f30, and the negative meniscus lens L34 When the focal length is f34, it is preferable that the following expression (1) is satisfied.

  −0.6 <f30 / f34 <−0.1 (1)

  Conditional expression (1) defines an appropriate ratio between the focal length f30 of the third lens group G3 and the focal length f34 of the negative meniscus lens L34. In conditional expression (1), if the value is below the lower limit value, the variation in curvature of field due to zooming (magnification) increases, which is not preferable. On the other hand, in the conditional expression (1), if the upper limit value is exceeded, the total optical length of the third lens group G3 increases, and accordingly, the total lens length at the wide angle end increases, and the effective diameter of the first lens group G1 increases. turn into. In order to avoid this, it is sufficient to increase the refractive power of the third lens group G3 and decrease the refractive power of the fourth lens group G4, but this is not preferable because spherical aberration increases. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to −0.56. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to −0.20.

  Further, in the zoom lens ZL, in order to perform good aberration correction with the entire lens length at the wide angle end being short, the focal length of the front lens group G3F in the third lens group G3 is set to fG3F, and the focal length of the negative meniscus lens L34 is set. It is preferable that the following expression (2) is satisfied, where f34 is the average refractive index N3n of the negative meniscus lens L32 and the negative meniscus lens L34.

  −0.24 <fG3F / (f34 × N3n) <− 0.05 (2)

  Conditional expression (2) indicates that in the third lens group G3, the focal length fG3F of the front group G3F, the focal length f34 of the negative meniscus lens L34, and the average refractive index N3n of the negative meniscus lens L32 and the negative meniscus lens L34 are appropriate. It defines the relationship. In conditional expression (2), if the value falls below the lower limit, the variation in field curvature accompanying zooming (magnification) in the third lens group G3 becomes large, which is not preferable. On the other hand, if the upper limit value in conditional expression (2) is exceeded, spherical aberration increases in the third lens group G3, 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 −0.23. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to −0.08.

  In the zoom lens ZL, when the wide-angle end focal length of the entire lens system is Fw, the focal length of the third lens group is f30, and the telephoto end focal length of the entire lens system is Ft, the following equation (3) Is preferably satisfied.

0.03 <(Fw × f30) / Ft ² <0.08 (3)

  Conditional expression (3) defines an appropriate relationship among the wide-angle end focal length Fw of the entire lens system, the focal length f30 of the third lens group G3, and the telephoto end focal length Ft of the entire lens system. In conditional expression (3), if the lower limit is not reached, large spherical aberration occurs, which is not preferable. On the other hand, in the conditional expression (3), if the upper limit value is exceeded, the effective diameter of the first lens group G1 becomes large. In order to avoid this, it is sufficient to increase the positive refractive power of the first lens group G1 to shorten the entire length of the lens, but this is not preferable because the aberration of field curvature at the telephoto end increases. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to 0.035. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to 0.06.

  In the zoom lens ZL, when the thickness on the optical axis of the positive lens L33 is d33 and the thickness on the optical axis of the third lens group G3 is d30, it is preferable that the following expression (4) is satisfied. .

  0.28 <d33 / d30 <0.60 (4)

  Conditional expression (4) defines an appropriate ratio between the thickness d33 of the positive lens L33 on the optical axis and the thickness d30 of the third lens group G3 on the optical axis. In conditional expression (4), if the lower limit is not reached, spherical aberration increases, which is not preferable. On the other hand, in the conditional expression (4), if the upper limit value is exceeded, the thickness of the third lens group G3 on the optical axis increases, and the total lens length also increases. In order to avoid this, it is sufficient to increase the positive refractive power of the first lens group G1 to shorten the entire length of the lens, but this is not preferable because the aberration of field curvature at the telephoto end increases. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 0.29. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 0.50.

  Each embodiment will be described below with reference to the accompanying drawings. As described above, the zoom lens ZL (lens system) according to each embodiment has a first lens group G1 having a positive refractive power, which is arranged in order from the object side along the optical axis, and a negative refractive power. A second lens group G2, an aperture stop S for adjusting the amount of light, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and a solid-state imaging device And a low-pass filter LPF for cutting a spatial frequency equal to or higher than the limit resolution and a cover glass CG of a solid-state imaging device. The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side, and a cemented lens obtained by bonding the positive lens L12, arranged in order from the object side. The second lens group G2 includes a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave lens L22, and a positive lens L23, which are arranged in order from the object side. The third lens group G3 includes, in order from the object side, a positive lens L31 having a convex surface facing the object side, a negative meniscus lens L32 having a convex surface facing the object side, and a biconvex lens (positive lens) L33. And a front lens group G3F having a positive refractive power and a negative meniscus lens L34 having a convex surface facing the object side. In the third lens group G3, a flare cut stop (also having a field stop effect) FS is disposed between the front group G3F and the negative meniscus lens L34. The fourth lens group G4 includes a positive lens L41 having a convex shape whose object side lens surface is strong on the object side.

  In the zoom lens ZL having the above-described configuration, when zooming from the wide-angle end state to the telephoto end state, the first lens group G1 and the third lens group G3 are moved to the object side, and the second lens group G2 is moved along the optical axis along a concave locus toward the object side, and the fourth lens group G4 is moved along the optical axis along a locus convex toward the object side. The fourth lens group G4 is movable on the optical axis when the photographing object is focused at a finite distance. The third lens group G3 is a so-called anti-vibration lens group that corrects image blur caused by camera shake by vibrating the front group G3F in a direction perpendicular to the optical axis.

  Tables 1 to 6 are shown below, but these are tables of specifications in the first to sixth examples. In each table, F is the focal length of the entire lens system, FNO is the F number, ω is the half angle of view, β is the shooting magnification, D0 is the object closest to the object in the first lens group G1 from the object. The distance from the lens L11 to the object side lens surface is indicated, Bf is the back focus, and TL is the total lens length. The surface number is the order of the lens surfaces from the object side along the direction in which the light beam travels, r is the radius of curvature of each lens surface, and d is the distance from each optical surface to the next optical surface (or image surface). The inter-surface distance, which is the distance on the optical axis, nd is the refractive index with respect to the d-line (wavelength 587.6 nm), and νd is the Abbe number with respect to the d-line. In the table, values corresponding to the conditional expressions (1) to (4) are also shown.

  In the table, “mm” is generally used as the focal length F, the radius of curvature r, the surface interval d, and other length units. However, since the optical system can obtain the same optical performance even when proportionally enlarged or proportionally reduced, the unit is not limited to “mm”, and other appropriate units can be used. In the table, the radius of curvature “∞” indicates a plane or an opening, and the air refractive index “1.00000” is omitted.

Also, in the table, the aspherical surface marked with * is the optical axis from the tangential plane at the apex of the aspherical surface to the position on the aspherical surface at the height y, where y is the height in the direction perpendicular to the optical axis. When the distance along the sag (sag amount) is S (y), the radius of curvature of the reference sphere (paraxial radius of curvature) is r, the conic coefficient is K, and the n-th aspherical coefficient is An, the following equation It is represented by (a). In each example, the secondary aspheric coefficient A2 is 0, and the description thereof is omitted. En represents x10 ⁿ . For example, 1.234E-05 = 1.234 × 10 ⁻⁵ .

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

(First embodiment)
A first embodiment will be described with reference to FIGS. FIG. 2 shows the configuration of the zoom lens ZL according to the first embodiment, and the change in the focal length state from the wide-angle end state (W) to the telephoto end state (T) through the intermediate focal length state (M), that is, The movement of each lens group during zooming is shown.

  Table 1 shows a table of specifications in the first embodiment. The surface numbers 1 to 24 in Table 1 correspond to the surfaces 1 to 24 shown in FIG. In the first example, the object side lens surface of the negative meniscus lens L21, the image side lens surface of the positive meniscus lens L23, the object side lens surface of the positive meniscus lens L31, and the image side lens surface of the biconvex lens L33, that is, The lens surfaces of the fourth surface, the ninth surface, the eleventh surface, and the fifteenth surface are all aspherical.

  In the table, the axial air space between the first lens group G1 and the second lens group G2 is d3, the axial air space between the second lens group G2 and the aperture stop S is d9, and the third lens group. The axial air space between G3 and the fourth lens group G4 is d18, and the axial air space between the fourth lens group G4 and the low-pass filter LPF is d20. These on-axis air spacings, d3, d9, d18 and d20, change during zooming.

(Table 1)
[Overall specifications]
Wide angle end Intermediate focal length Telephoto end F 5.20 to 15.00 to 29.75
FNO 3.0 to 4.4 to 5.7
ω -39.32 to -14.78 to -7.68
[Lens specifications]
Surface number r d nd νd
1 21.3725 0.8000 1.903660 31.31
2 15.7730 3.4000 1.603000 65.47
3 159.6044 (d3 = variable)
4 * 20.6225 0.7000 1.851350 40.10
5 4.8000 3.0000
6 -6.8565 0.6000 1.755000 52.29
7 17.0023 0.3000
8 7.3490 1.4000 1.821140 24.06
9 * 154.8042 (d9 = variable)
10 Aperture stop S 0.3000
11 * 4.6153 1.5000 1.768020 49.23
12 11.0713 0.1000
13 7.2985 0.8000 1.903660 31.31
14 2.8000 2.9000 1.592010 67.05
15 * -20.7158 0.3000
16 Flare cut aperture FS 0.7000
17 17.5815 0.6000 1.883000 40.77
18 8.7426 (d18 = variable)
19 11.0019 1.1000 1.516800 64.12
20 24.7103 (d20 = variable)
21 ∞ 0.8000 1.516800 64.12
22 ∞ 0.5000
23 ∞ 0.5000 1.516800 64.12
24 ∞ (Bf)
[Aspherical data]
4th page
K = 11.8959, A4 = 2.18410E-04, A6 = -2.69740E-06, A8 = 0.00000E + 00, A10 = 0.00000E + 00
9th page
K = -100.0000, A4 = 9.20510E-04, A6 = 4.77340E-05, A8 = -4.83050E-06, A10 = 2.35060E-07
11th page
K = -0.4635, A4 = 1.74700E-04, A6 = 2.29920E-05, A8 = 0.00000E + 00, A10 = 0.00000E + 00
15th page
K = -100.0000, A4 = 5.55600E-04, A6 = 1.64610E-04, A8 = 0.00000E + 00, A10 = 0.00000E + 00
[Variable interval during focusing]
Infinity Closest distance F, β 5.20000 15.00000 29.75200 -0.05000 -0.05000 -0.05000
D0 ∞ ∞ ∞ 94.3045 274.9835 540.9729
d3 0.78498 12.19483 20.65553 0.78498 12.19483 20.65553
d9 7.95930 2.23455 0.85391 7.95930 2.23455 0.85391
d18 3.07965 1.73668 8.77541 2.24637 0.47870 6.36698
d20 2.91543 9.94349 9.98482 3.74870 11.20147 12.39325
Bf 0.40631 0.40631 0.40631 0.40631 0.40631 0.40631
TL 35.44566 46.81584 60.97596 35.44566 46.81583 60.97596
[Moving amount of image stabilizing lens group and moving amount of image plane during image stabilization]
F, β 5.20000 15.00000 29.75200 -0.05000 -0.05000 -0.05000
Lens ± 0.055 ± 0.065 ± 0.071 ± 0.055 ± 0.064 ± 0.070
Image plane ± 0.110 ± 0.186 ± 0.262 ± 0.110 ± 0.186 ± 0.262
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 49.90959
G2 4 -5.45518
G3 11 7.80739
G4 19 37.35259
[Conditional expression]
(1) f30 / f34 = -0.384
(2) fG3F / (F34 × N3n) = − 0.182
(3) (Fw × F30) / Ft ² = 0.046
(4) d33 / d30 = 0.420

  As can be seen from the table of specifications shown in Table 1, it can be seen that the zoom lens ZL according to the present example satisfies all the conditional expressions (1) to (4).

  FIG. 3 is a diagram of various aberrations in the infinitely focused state and the lateral aberration diagram at the time of image stabilization in the first embodiment, and FIG. 3A is a diagram in the wide angle end state (F = 5.20 mm). FIG. 3B shows the case of the intermediate focal length state (F = 15.00 mm), and FIG. 3C shows the case of the telephoto end state (F = 29.75 mm). FIG. 4 is a diagram of various aberrations in the close-up shooting distance focus state and lateral aberration diagram at the time of image stabilization in the first embodiment. FIG. 4A is a wide-angle end state (Rw = 130 mm). 4B shows the case of the intermediate focal length state (Rm = 322 mm), and FIG. 4C shows the case of the telephoto end state (Rt = 602 mm).

  In each aberration diagram, FNO is the F number, Y is the image height, D is the d-line (wavelength 587.6 nm), G is the g-line (wavelength 435.6 nm), C is the C-line (wavelength 656.3 nm), F represents F line (wavelength 486.1 nm), respectively. In the aberration diagrams showing astigmatism, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. In the aberration diagram showing the lateral chromatic aberration, the d-line is shown as a reference. The explanation of the above aberration diagrams is the same in the other examples, and the explanation is omitted.

  As is apparent from the respective aberration diagrams, in the zoom lens ZL according to the first example, even in each focal length state from the wide-angle end state to the telephoto end state in the infinite focus state, It can be seen that even in each focal length state from the wide-angle end state to the telephoto end state, various aberrations are well corrected and excellent imaging performance is obtained.

  In addition, by mounting the zoom lens ZL of the first embodiment, excellent optical performance can be ensured also in a digital single lens reflex camera (optical apparatus, see FIG. 1).

(Second embodiment)
A second embodiment will be described with reference to FIGS. FIG. 5 shows the configuration of the zoom lens ZL according to the second embodiment, and changes in the focal length state from the wide-angle end state (W) through the intermediate focal length state (M) to the telephoto end state (T), that is, The movement of each lens group during zooming is shown.

  Table 2 shows a table of specifications in the second embodiment. In addition, the surface numbers 1-26 in Table 2 respond | correspond to the surfaces 1-26 shown in FIG. In the second embodiment, the object side lens surface of the negative meniscus lens L21, the object side lens surface of the positive meniscus lens L23, the object side lens surface of the negative meniscus lens L32, and the image side lens surface of the biconvex lens L33, that is, The lens surfaces of the fifth surface, the ninth surface, the fifteenth surface and the seventeenth surface are all formed in an aspherical shape. In the second embodiment, the flare-cut stop (which also has a field stop effect) FS is not between the front group G3F and the negative meniscus lens L34, but the object side and the image side of the second lens group G2. Also placed.

  In the table, the axial air space between the first lens group G1 and the second lens group G2 is d3, the axial air space between the second lens group G2 and the aperture stop S is d11, and the third lens group. The axial air space between G3 and the fourth lens group G4 is d20, and the axial air space between the fourth lens group G4 and the low-pass filter LPF is d22. These axial air spacings, d3, d11, d20 and d22, change during zooming.

(Table 2)
[Overall specifications]
Wide angle end Intermediate focal length Telephoto end F 5.24 to 15.00 to 29.75
FNO 3.1 to 4.4 to 5.7
ω -39.10 to -14.61 to -7.51
[Lens specifications]
Surface number r d nd νd
1 23.0699 1.2000 1.903660 31.31
2 16.3328 5.4000 1.603000 65.47
3 391.4407 (d3 = variable)
4 Flare cut aperture FS -0.2000
5 * 30.6357 1.0000 1.851350 40.10
6 5.0364 2.9000
7 -20.4922 1.0000 1.754999 52.32
8 6.9457 0.4000
9 * 6.9097 2.1000 1.821140 24.06
10 69.7311 0.3000
11 Flare cut aperture FS (d11 = variable)
12 Aperture stop S 0.3000
13 5.1369 1.3000 1.772500 49.61
14 6.6563 0.1000
15 * 4.8548 1.0000 1.821140 24.06
16 3.0055 3.3000 1.496970 82.42
17 * -19.3974 0.2000
18 Flare cut aperture FS 1.2384
19 18.5170 1.0000 1.883000 40.77
20 11.0890 (d20 = variable)
21 19.3250 1.5000 1.516800 64.12
22 392.2566 (d22 = variable)
23 ∞ 0.8000 1.516800 64.12
24 ∞ 0.5000
25 ∞ 0.5000 1.516800 64.12
26 ∞ (Bf)
[Aspherical data]
5th page
K = 7.4979, A4 = 9.95360E-05, A6 = -2.23550E-06, A8 = 0.00000E-00, A10 = 0.00000E-00
9th page
K = -0.7381, A4 = 1.56750E-04, A6 = -3.38830E-05, A8 = 4.21200E-06, A10 = -1.57770E-07
15th page
K = 0.7718, A4 = -1.25460E-03, A6 = -7.44420E-05, A8 = 2.90110E-06, A10 = -8.20110E-07
17th page
K = -100.0000, A4 = 4.69770E-04, A6 = 1.77220E-04, A8 = 0.00000E-00, A10 = 0.00000E-00
[Variable interval during focusing]
Infinity Closest distance F, β 5.24000 15.00000 29.75200 -0.05000 -0.05000 -0.05000
D0 ∞ ∞ ∞ 92.0615 266.9210 520.2787
d3 1.13151 12.92049 20.87896 1.13151 12.92049 20.87896
d11 8.12363 2.00299 0.55279 8.12363 2.00299 0.55279
d20 2.33991 2.18605 10.61960 1.44311 0.76822 7.58541
d22 1.32158 7.14378 5.21850 2.21838 8.56162 8.25269
Bf 2.06299 2.06299 2.06299 2.06299 2.06299 2.06299
TL 40.81808 52.15477 65.17130 40.81808 52.15477 65.17129
[Moving amount of image stabilizing lens group and moving amount of image plane during image stabilization]
F, β 5.24000 15.00000 29.75200 -0.05000 -0.05000 -0.05000
Lens ± 0.135 ± 0.109 ± 0.104 ± 0.143 ± 0.111 ± 0.107
Image plane ± 0.110 ± 0.186 ± 0.262 ± 0.110 ± 0.186 ± 0.262
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 50.44305
G2 5 -5.57648
G3 13 8.22766
G4 21 39.27736
[Conditional expression]
(1) f30 / f34 = -0.246
(2) fG3F / (F34 × N3n) = − 0.128
(3) (Fw × F30) / Ft ² = 0.049
(4) d33 / d30 = 0.405

  As can be seen from the table of specifications shown in Table 2, it can be seen that the zoom lens ZL according to the present example satisfies all the conditional expressions (1) to (4).

  FIG. 6 is a diagram of various aberrations in the infinite focus state and the lateral aberration diagram at the time of image stabilization in the second embodiment, and FIG. 6A is a diagram in the wide-angle end state (F = 5.24 mm). FIG. 6B shows the case of the intermediate focal length state (F = 15.00 mm), and FIG. 6C shows the case of the telephoto end state (F = 29.75 mm). FIG. 7 is a diagram showing various aberrations in the close-up shooting distance focus state and lateral aberration diagram at the time of image stabilization in the second embodiment. FIG. 7A is a wide-angle end state (Rw = 133 mm). FIG. 7B shows the case of the intermediate focal length state (Rm = 319 mm), and FIG. 7C shows the case of the telephoto end state (Rt = 585 mm).

  As is apparent from the respective aberration diagrams, in the zoom lens ZL according to the second example, even in each focal length state from the wide-angle end state to the telephoto end state in the infinite focus state, It can be seen that even in each focal length state from the wide-angle end state to the telephoto end state, various aberrations are well corrected and excellent imaging performance is obtained.

  In addition, by mounting the zoom lens ZL of the second embodiment, excellent optical performance can be ensured also in a digital single lens reflex camera (optical apparatus, see FIG. 1).

(Third embodiment)
A third embodiment will be described with reference to FIGS. FIG. 8 shows the configuration of the zoom lens ZL according to Example 3, and the change in the focal length state from the wide-angle end state (W) through the intermediate focal length state (M) to the telephoto end state (T). The movement of each lens group during zooming is shown.

  Table 3 shows a table of specifications in the third embodiment. The surface numbers 1 to 24 in Table 3 correspond to the surfaces 1 to 24 shown in FIG. In the third embodiment, the object side lens surface of the negative meniscus lens L21, the image side lens surface of the positive meniscus lens L23, the object side lens surface of the positive meniscus lens L31, and the image side lens surface of the biconvex lens L33, that is, The lens surfaces of the fourth surface, the ninth surface, the eleventh surface, and the fifteenth surface are all aspherical.

  In the table, the axial air space between the first lens group G1 and the second lens group G2 is d3, the axial air space between the second lens group G2 and the aperture stop S is d9, and the third lens group. The axial air space between G3 and the fourth lens group G4 is d18, and the axial air space between the fourth lens group G4 and the low-pass filter LPF is d20. These on-axis air spacings, d3, d9, d18 and d20, change during zooming.

(Table 3)
[Overall specifications]
Wide angle end Intermediate focal length Telephoto end F 5.24 to 15.00 to 29.75
FNO 3.1 to 4.4 to 5.7
ω -39.32 to -14.76 to -7.66
[Lens specifications]
Surface number r d nd νd
1 21.7401 0.8000 1.903660 31.31
2 16.0416 3.4000 1.603000 65.47
3 180.6875 (d3 = variable)
4 * 19.4855 0.7000 1.851350 40.10
5 4.8000 3.0000
6 -6.9420 0.6000 1.755000 52.29
7 16.5264 0.3000
8 7.1421 1.4000 1.821140 24.06
9 * 82.7970 (d9 = variable)
10 Aperture stop S 0.3000
11 * 4.5916 1.5000 1.768020 49.23
12 13.8049 0.1000
13 9.8148 0.8000 1.803840 33.89
14 2.6725 2.9000 1.592010 67.05
15 * -21.6333 0.3000
16 Flare cut aperture FS 0.7000
17 22.2291 0.6000 1.883000 40.77
18 9.8358 (d18 = variable)
19 11.4427 1.1000 1.516800 64.12
20 27.1787 (d20 = variable)
21 ∞ 0.8000 1.516800 64.12
22 ∞ 0.5000
23 ∞ 0.5000 1.516800 64.12
24 ∞ (Bf)
[Aspherical data]
4th page
K = 10.4162, A4 = 1.94090E-04, A6 = -2.59290E-06, A8 = 0.00000E-00, A10 = 0.00000E-00
9th page
K = -100.0000, A4 = 9.84400E-04, A6 = 4.51250E-05, A8 = -4.23140E-06, A10 = 2.01510E-07
11th page
K = -0.2282, A4 = -9.88550E-05, A6 = 1.21650E-05, A8 = 0.00000E-00, A10 = 0.00000E-00
15th page
K = -100.0000, A4 = 8.59580E-04, A6 = 1.42440E-04, A8 = 0.00000E-00, A10 = 0.00000E-00
[Variable interval during focusing]
Infinity Closest distance F, β 5.24000 15.00000 29.75200 -0.05000 -0.05000 -0.05000
D0 ∞ ∞ ∞ 94.2415 274.9204 540.9099
d3 0.78497 12.19482 20.65552 0.78497 12.19482 20.65552
d9 7.95277 2.22802 0.84738 7.95277 2.28802 0.84738
d18 3.04423 1.70126 8.73999 2.21095 0.44328 6.33156
d20 2.96445 9.99251 10.03384 3.79772 11.25049 12.44227
Bf 0.40631 0.40631 0.40631 0.40631 0.40631 0.40631
TL 35.45274 46.82291 60.98303 35.45273 46.82291 60.98303
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 49.90959
G2 4 -5.45518
G3 11 7.80739
G4 19 37.35259
[Conditional expression]
(1) f30 / f34 = -0.382
(2) fG3F / (F34 × N3n) = − 0.186
(3) (Fw × F30) / Ft ² = 0.046
(4) d33 / d30 = 0.420

  As can be seen from the table of specifications shown in Table 3, it can be seen that the zoom lens ZL according to the present example satisfies all the conditional expressions (1) to (4).

  FIG. 9 is a diagram showing various aberrations in the infinite focus state in the third embodiment and a lateral aberration diagram at the time of image stabilization. FIG. 9A shows the case of the wide-angle end state (F = 5.24 mm). FIG. 9B shows the case of the intermediate focal length state (F = 15.00 mm), and FIG. 9C shows the case of the telephoto end state (F = 29.75 mm). FIG. 10 is a diagram of various aberrations in the close-up shooting distance focus state and lateral aberration diagram at the time of image stabilization in the third embodiment, and FIG. 10A is the wide-angle end state (Rw = 130 mm). FIG. 10B shows the case of the intermediate focal length state (Rm = 322 mm), and FIG. 10C shows the case of the telephoto end state (Rt = 602 mm).

  As is apparent from the respective aberration diagrams, in the zoom lens ZL according to the third example, even in each focal length state from the wide-angle end state to the telephoto end state in the infinite focus state, It can be seen that even in each focal length state from the wide-angle end state to the telephoto end state, various aberrations are well corrected and excellent imaging performance is obtained.

  Further, by mounting the zoom lens ZL of the third embodiment, excellent optical performance can be ensured also in a digital single lens reflex camera (optical apparatus, see FIG. 1).

(Fourth embodiment)
A fourth embodiment will be described with reference to FIGS. 11 to 13 and Table 4. FIG. FIG. 11 shows the configuration of the zoom lens ZL according to Example 4, and the change in the focal length state from the wide-angle end state (W) through the intermediate focal length state (M) to the telephoto end state (T). The movement of each lens group during zooming is shown.

  Table 4 shows a table of specifications in the fourth embodiment. The surface numbers 1 to 24 in Table 4 correspond to the surfaces 1 to 24 shown in FIG. In the fourth example, the object side lens surface of the negative meniscus lens L21, the image side lens surface of the positive meniscus lens L23, the object side lens surface of the positive meniscus lens L31, and the image side lens surface of the biconvex lens L33, that is, The lens surfaces of the fourth surface, the ninth surface, the eleventh surface, and the fifteenth surface are all aspherical.

  In the table, the axial air space between the first lens group G1 and the second lens group G2 is d3, the axial air space between the second lens group G2 and the aperture stop S is d9, and the third lens group. The axial air space between G3 and the fourth lens group G4 is d18, and the axial air space between the fourth lens group G4 and the low-pass filter LPF is d20. These on-axis air spacings, d3, d9, d18 and d20, change during zooming.

(Table 4)
[Overall specifications]
Wide angle end Intermediate focal length Telephoto end F 5.20 to 15.00 to 35.00
FNO 2.9 to 4.2 to 5.8
ω -39.31--14.78--7.69
[Lens specifications]
Surface number r d nd νd
1 22.6580 0.9000 1.903660 31.31
2 16.7546 3.6000 1.603000 65.47
3 173.7035 (d3 = variable)
4 * 21.9913 0.8000 1.851350 40.10
5 5.0876 3.2000
6 -6.8073 0.7000 1.755000 52.29
7 21.2947 0.3000
8 8.0515 1.5000 1.821140 24.06
9 * 209.2176 (d9 = variable)
10 Aperture stop S 0.3000
11 * 4.8173 1.7000 1.743300 49.32
12 10.9922 0.1000
13 6.8149 0.8000 1.903660 31.31
14 2.8338 3.1000 1.592010 67.05
15 * -25.9491 0.3000
16 Flare cut aperture FS 0.7000
17 18.7998 0.7000 1.883000 40.77
18 9.2180 (d18 = variable)
19 11.1802 1.2000 1.516800 64.12
20 28.5786 (d20 = variable)
21 ∞ 0.8000 1.516800 64.12
22 ∞ 0.5000
23 ∞ 0.5000 1.516800 64.12
24 ∞ (Bf)
[Aspherical data]
4th page
K = 12.6108, A4 = 1.85220E-04, A6 = -2.26860E-06, A8 = 0.00000E-00, A10 = 0.00000E-00
9th page
K = -100.0000, A4 = 7.77520E-04, A6 = 2.59180E-05, A8 = -2.13670E-06, A10 = 9.21200E-08
11th page
K = -0.2317, A4 = -9.459990-05, A6 = 6025740E-06, A8 = 0.00000E-00, A10 = 0.00000E-00
15th page
K = -100.0000, A4 = 1.03610E-03, A6 = 6.26560E-05, A8 = 0.00000E-00, A10 = 0.00000E-00
[Variable interval during focusing]
Infinity Closest distance F, β 5.20000 15.00000 29.75200 -0.05000 -0.05000 -0.05000
D0 ∞ ∞ ∞ 93.4240 273.3649 621.7957
d3 0.83822 12.69829 23.53396 0.83822 12.69829 23.53396
d9 8.49164 2.26178 0.68535 8.49164 2.26178 0.68535
d19 3.33154 1.73374 12.46171 2.50392 0.52898 9.55384
d20 1.98878 9.21679 7.74807 2.81640 10.42155 10.65594
Bf 0.93390 0.93390 0.93390 0.93390 0.93390 0.93390
TL 37.28407 48.54450 67.06299 37.28407 48.54450 67.06299
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 49.90959
G2 4 -5.45518
G3 11 7.60000
G4 19 38.47541
[Conditional expression]
(1) f30 / f34 = -0.241
(2) fG3F / (F34 × N3n) = − 0.120
(3) (Fw × F30) / Ft ² = 0.045
(4) d33 / d30 = 0.304

  As can be seen from the table of specifications shown in Table 4, it can be seen that the zoom lens ZL according to the present example satisfies all the conditional expressions (1) to (4).

  FIG. 12 is a diagram of various aberrations in the infinitely focused state and the lateral aberration diagram at the time of image stabilization in the fourth example. FIG. 12A shows the case of the wide-angle end state (F = 5.20 mm). FIG. 12B shows the case of the intermediate focal length state (F = 15.00 mm), and FIG. 12C shows the case of the telephoto end state (F = 29.75 mm). FIG. 13 is a diagram of various aberrations in the close-up shooting distance focus state of the fourth embodiment and a lateral aberration diagram at the time of image stabilization. FIG. 13A is a wide-angle end state (Rw = 131 mm). FIG. 13B shows the case of the intermediate focal length state (Rm = 322 mm), and FIG. 13C shows the case of the telephoto end state (Rt = 689 mm).

  As is apparent from the respective aberration diagrams, in the zoom lens ZL according to the fourth example, even in each focal length state from the wide-angle end state to the telephoto end state in the infinite focus state, It can be seen that even in each focal length state from the wide-angle end state to the telephoto end state, various aberrations are well corrected and excellent imaging performance is obtained.

  Further, by mounting the zoom lens ZL of the fourth embodiment, excellent optical performance can be ensured also in a digital single lens reflex camera (optical apparatus, see FIG. 1).

(5th Example)
The fifth embodiment will be described with reference to FIGS. 14 to 16 and Table 5. FIG. FIG. 14 shows the configuration of the zoom lens ZL according to Example 5, and the change in the focal length state from the wide-angle end state (W) through the intermediate focal length state (M) to the telephoto end state (T). The movement of each lens group during zooming is shown.

  Table 5 shows a table of specifications in the fifth embodiment. The surface numbers 1 to 24 in Table 5 correspond to the surfaces 1 to 24 shown in FIG. In the fifth example, the object side lens surface of the negative meniscus lens L21, the image side lens surface of the positive meniscus lens L23, the object side lens surface of the positive meniscus lens L31, and the image side lens surface of the biconvex lens L33, that is, The lens surfaces of the fourth surface, the ninth surface, the eleventh surface, and the fifteenth surface are all aspherical.

  In the table, the axial air space between the first lens group G1 and the second lens group G2 is d3, the axial air space between the second lens group G2 and the aperture stop S is d9, and the third lens group. The axial air space between G3 and the fourth lens group G4 is d18, and the axial air space between the fourth lens group G4 and the low-pass filter LPF is d20. These on-axis air spacings, d3, d9, d18 and d20, change during zooming.

(Table 5)
[Overall specifications]
Wide angle end Intermediate focal length Telephoto end F 5.20 to 15.00 to 29.75
FNO 3.1-4.5-5.9
ω -39.35 to -14.78 to -7.68
[Lens specifications]
Surface number r d nd νd
1 20.9332 0.8000 1.903660 31.31
2 15.6096 3.4000 1.603000 65.47
3 132.9284 (d3 = variable)
4 * 21.5411 0.7000 1.851350 40.10
5 4.8000 3.0000
6 -6.6897 0.6000 1.755000 52.29
7 17.5831 0.3000
8 7.1922 1.4000 1.821140 24.06
9 * 148.9436 (d9 = variable)
10 Aperture stop S 0.3000
11 * 5.2502 1.5000 1.768020 49.23
12 12.4615 0.1000
13 6.7844 0.8000 2.000690 25.46
14 3.2207 2.9000 1.617200 54.00
15 * -20.3248 0.3000
16 Flare cut aperture FS 0.7000
17 13.8399 0.6000 1.883000 40.77
18 6.8992 (d18 = variable)
19 11.2782 1.1000 1.516800 64.12
20 35.2359 (d20 = variable)
21 ∞ 0.8000 1.516800 64.12
22 ∞ 0.5000
23 ∞ 0.5000 1.516800 64.12
24 ∞ (Bf)
[Aspherical data]
4th page
K = 13.5658, A4 = 2.52830E-04, A6 = -2.78780E-06, A8 = 0.00000E-00, A10 = 0.00000E-00
9th page
K = -100.0000, A4 = 9.90800E-04, A6 = 5.50150E-05, A8 = -5.44920E-06, A10 = 2.55520E-07
11th page
K = -0.4153, A4 = 6.82330E-05, A6 = 1.63960E-05, A8 = 0.00000E-00, A10 = 0.00000E-00
15th page
K = -100.0000, A4 = 2.62350E-04, A6 = 1.66560E-04, A8 = 0.00000E-00, A10 = 0.00000E-00
[Variable interval during focusing]
Infinity Closest distance F, β 5.20000 15.00000 29.75200 -0.05000 -0.05000 -0.05000
D0 ∞ ∞ ∞ 94.3368 275.1432 536.4708
d3 0.72810 12.20929 21.07791 0.72810 12.20929 21.07791
d9 8.17997 2.36105 1.11642 8.17997 2.36105 1.11642
d18 2.87007 1.52418 9.47367 2.17479 0.42630 7.32129
d20 3.13770 10.14586 9.82036 3.83298 11.24374 11.97274
Bf 0.70245 0.70246 0.70243 0.70270 0.70271 0.70267
TL 35.91830 47.24285 62.49080 35.91855 47.24310 62.49104
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 49.90959
G2 4 -5.45518
G3 11 8.00000
G4 19 31.60191
[Conditional expression]
(1) f30 / f34 = -0.493
(2) fG3F / (F34 × N3n) = − 0.220
(3) (Fw × F30) / Ft ² = 0.047
(4) d33 / d30 = 0.420

  As can be seen from the table of specifications shown in Table 5, it can be seen that the zoom lens ZL according to the present example satisfies all the conditional expressions (1) to (4).

  FIG. 15 is a diagram of various aberrations in the infinitely focused state according to the fifth embodiment and a lateral aberration diagram at the time of image stabilization. FIG. 15A shows the case of the wide angle end state (F = 5.20 mm), and FIG. FIG. 15B shows the case of the intermediate focal length state (F = 15.00 mm), and FIG. 15C shows the case of the telephoto end state (F = 35.00 mm). FIG. 16 is a diagram showing various aberrations in the close-up shooting distance focus state and lateral aberration diagram at the time of image stabilization in the fifth embodiment, and FIG. 16A is the wide-angle end state (Rw = 131 mm). FIG. 16B shows the case of the intermediate focal length state (Rm = 322 mm), and FIG. 16C shows the case of the telephoto end state (Rt = 689 mm).

  As is apparent from the respective aberration diagrams, in the zoom lens ZL according to the fifth example, even in each focal length state from the wide-angle end state to the telephoto end state in the infinite focus state, It can be seen that even in each focal length state from the wide-angle end state to the telephoto end state, various aberrations are well corrected and excellent imaging performance is obtained.

  In addition, by mounting the zoom lens ZL of the fifth embodiment, excellent optical performance can be ensured also in a digital single lens reflex camera (optical apparatus, see FIG. 1).

(Sixth embodiment)
The sixth embodiment will be described with reference to FIGS. 17 to 19 and Table 6. FIG. FIG. 17 shows the configuration of the zoom lens ZL according to Example 6, and the change in the focal length state from the wide-angle end state (W) through the intermediate focal length state (M) to the telephoto end state (T). The movement of each lens group during zooming is shown.

  Table 6 shows a table of specifications in the sixth embodiment. The surface numbers 1 to 24 in Table 6 correspond to the surfaces 1 to 24 shown in FIG. In the sixth embodiment, the object side lens surface of the negative meniscus lens L21, the image side lens surface of the positive meniscus lens L23, the object side lens surface of the positive meniscus lens L31, and the image side lens surface of the biconvex lens L33, that is, The lens surfaces of the fourth surface, the ninth surface, the eleventh surface, and the fifteenth surface are all aspherical.

  In the table, the axial air space between the first lens group G1 and the second lens group G2 is d3, the axial air space between the second lens group G2 and the aperture stop S is d9, and the third lens group. The axial air space between G3 and the fourth lens group G4 is d18, and the axial air space between the fourth lens group G4 and the low-pass filter LPF is d20. These on-axis air spacings, d3, d9, d18 and d20, change during zooming.

(Table 6)
[Overall specifications]
Wide angle end Intermediate focal length Telephoto end F 5.20 to 15.00 to 35.00
FNO 2.9 to 4.2 to 5.8
ω -39.27--14.79--6.53
[Lens specifications]
Surface number r d nd νd
1 22.6580 0.9000 1.903660 31.31
2 16.7546 3.6000 1.603000 65.47
3 173.7135 (d3 = variable)
4 * 21.9913 0.8000 1.851350 40.10
5 5.0876 3.2000
6 -6.8073 0.7000 1.755000 52.29
7 21.2947 0.3000
8 8.0515 1.5000 1.821140 24.06
9 * 209.2176 (d9 = variable)
10 Aperture stop S 0.3000
11 * 4.8173 1.7000 1.743300 49.32
12 10.9922 0.1000
13 6.8149 0.8000 1.903660 31.31
14 2.8338 3.1000 1.592010 67.05
15 * -25.9491 0.3000
16 Flare cut aperture FS 0.7000
17 18.7998 0.7000 1.883000 40.77
18 9.2180 (d18 = variable)
19 11.1802 1.2000 1.516800 64.12
20 28.5786 (d20 = variable)
21 ∞ 0.8000 1.516800 64.12
22 ∞ 0.5000
23 ∞ 0.5000 1.516800 64.12
24 ∞ (Bf)
[Aspherical data]
4th page
K = 12.6108, A4 = 1.85220E-04, A6 = -2.26860E-06, A8 = 0.00000E-00, A10 = 0.00000E-00
9th page
K = -100.0000, A4 = 7.77520E-04, A6 = 2.59180E-05, A8 = -2.13670E-06, A10 = 9.21200E-08
11th page
K = -0.2317, A4 = -9.45990E-05, A6 = 6.25740E-06, A8 = 0.00000E-00, A10 = 0.00000E-00
15th page
K = -100.0000, A4 = 1.03610E-03, A6 = 6.26560E-05, A8 = 0.00000E-00, A10 = 0.00000E-00
[Variable interval during focusing]
Infinity Closest distance F, β 5.20000 15.00000 29.75200 -0.05000 -0.05000 -0.05000
D0 ∞ ∞ ∞ 93.4240 273.3649 621.7957
d3 0.83822 12.69829 23.53397 0.83822 12.69829 23.53397
d9 8.49164 2.26178 0.68535 8.49164 2.26178 0.68535
d18 3.33154 1.73374 12.46170 2.50391 0.52898 9.55383
d20 1.98878 9.21679 7.74807 2.81640 10.42155 10.65594
Bf 0.93390 0.93390 0.93390 0.93390 0.93390 0.93390
TL 37.28407 48.54449 67.06298 37.28407 48.54449 67.06298
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 52.51005
G2 4 -5.66394
G3 11 8.03479
G4 19 34.71946
[Conditional expression]
(1) f30 / f34 = −0.379
(2) fG3F / (F34 × N3n) = − 0.182
(3) (Fw × F30) / Ft ² = 0.034
(4) d33 / d30 = 0.419

  As can be seen from the table of specifications shown in Table 6, it can be seen that the zoom lens ZL according to the present example satisfies all the conditional expressions (1) to (4).

  FIG. 18 is a diagram of various aberrations in the infinitely focused state and the lateral aberration diagram at the time of image stabilization in the sixth example. FIG. 18A shows the state at the wide-angle end state (F = 5.20 mm), and FIG. FIG. 18B shows the case of the intermediate focal length state (F = 15.00 mm), and FIG. 18C shows the case of the telephoto end state (F = 35.00 mm). FIG. 19 is a diagram of various aberrations in the close-up shooting distance focus state and lateral aberration diagram at the time of image stabilization in the sixth embodiment. FIG. 19A is a wide-angle end state (Rw = 131 mm). FIG. 19B shows an intermediate focal length state (Rm = 322 mm), and FIG. 19C shows a telephoto end state (Rt = 689 mm).

  As is apparent from the respective aberration diagrams, in the zoom lens ZL according to the sixth example, even in each focal length state from the wide-angle end state to the telephoto end state in the infinite focus state, It can be seen that even in each focal length state from the wide-angle end state to the telephoto end state, various aberrations are well corrected and excellent imaging performance is obtained.

  In addition, by mounting the zoom lens ZL of the sixth embodiment, excellent optical performance can be ensured also in a digital single lens reflex camera (optical apparatus, see FIG. 1).

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

  In each of the above-described embodiments, a four-group configuration is shown as a zoom lens, but the present invention can also be applied to other group configurations such as a fifth group and a sixth group.

  In each embodiment, all the lens groups are moved during zooming (magnification), but the present application does not limit this. For example, if the first lens group G1 is fixed, decentration aberration due to the fitting difference of the moving mechanism of the first lens group G1 due to zooming does not occur. Also, if the third lens group G3 is fixed as an image stabilization group during zooming, the image stabilization mechanism and the zooming mechanism can be separated.

  In addition, a single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to be a focusing lens group that performs focusing from an object at infinity to a near object. This focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (using an ultrasonic motor or the like). In particular, it is preferable that the fourth lens group G4 which is the lens group closest to the image plane is the focusing lens group.

  In each embodiment, focusing at a short distance is performed by the fourth lens group G4. However, if the zooming mechanism of the first lens group G1 and the short-range focusing mechanism can coexist, the first lens group G1 The short distance focusing may be performed in whole or in part. Further, if the zooming mechanism and the short-distance focusing mechanism with the zooming mechanism of the second lens group G2 can coexist, the short-distance focusing may be performed with the whole or a part of the second lens group G2.

  Alternatively, the lens group or the partial lens group may be vibrated in a direction perpendicular to the optical axis to correct the image blur caused by camera shake. In particular, it is preferable that the whole or part of the second lens group G2 and the third lens group G3 (particularly the front group G3F) is an anti-vibration lens group.

  Each lens surface may be an aspherical surface. The aspherical surface may be any of an aspherical surface by grinding, a glass mold aspherical surface in which a glass is formed into an aspherical shape, or a composite aspherical surface in which a resin is formed in an aspherical shape on the glass surface. The aspheric surface is preferably arranged in each lens group. In particular, the surface of the single lens is preferably an aspheric surface.

  The aperture stop S is preferably arranged in the vicinity of the third lens group G3, in particular, between the second lens group G2 and the third lens group G3. That role may be substituted.

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

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

FIG. 2 is a schematic cross-sectional view of a digital single-lens reflex camera equipped with the zoom lens of the present embodiment. 1 is a cross-sectional view illustrating a configuration of a zoom lens according to a first example, where (W) is a wide-angle end state in an infinite focus state, (M) is an intermediate focal length state in an infinite focus state, and (T ) Shows the telephoto end state at the infinity in-focus state. FIG. 5A is a diagram illustrating various aberrations in an infinitely focused state and a lateral aberration diagram at the time of image stabilization in the first embodiment, where (a) is a case in a wide-angle end state, and (b) is a case in an intermediate focal length state. , (C) is a case in the telephoto end state. FIG. 5A is a diagram illustrating various aberrations in a close-up shooting distance state in the first embodiment and a lateral aberration diagram at the time of image stabilization. FIG. 9A is a case in a wide-angle end state, and FIG. Yes, (c) is in the telephoto end state. FIG. 6 is a cross-sectional view illustrating a configuration of a zoom lens according to a second example, where (W) is a wide-angle end state in an infinite focus state, (M) is an intermediate focal length state in an infinite focus state, and (T ) Shows the telephoto end state at the infinity in-focus state. FIG. 6 is a diagram illustrating various aberrations in the infinite focus state in the second embodiment and a lateral aberration diagram during image stabilization, where (a) is a case in the wide-angle end state and (b) is a case in the intermediate focal length state. , (C) is a case in the telephoto end state. FIG. 6A is a diagram illustrating various aberrations in a close-up shooting distance state in the second embodiment and a lateral aberration diagram at the time of image stabilization. FIG. 5A is a case in a wide-angle end state, and FIG. Yes, (c) is in the telephoto end state. FIG. 10 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 3, wherein (W) is a wide-angle end state in an infinite focus state, (M) is an intermediate focal length state in an infinite focus state, and (T ) Shows the telephoto end state at the infinity in-focus state. FIG. 6A is a diagram illustrating various aberrations in an infinitely focused state and a lateral aberration diagram at the time of image stabilization in the third example, where (a) is a case in a wide-angle end state, and (b) is a case in an intermediate focal length state. , (C) is a case in the telephoto end state. FIG. 9A is a diagram illustrating various aberrations in a close-up shooting distance state in the third embodiment and a lateral aberration diagram at the time of image stabilization. FIG. 10A is a case in a wide-angle end state, and FIG. Yes, (c) is in the telephoto end state. FIG. 10 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 4, where (W) is a wide-angle end state in an infinite focus state, (M) is an intermediate focal length state in an infinite focus state, and (T ) Shows the telephoto end state at the infinity in-focus state. FIG. 10 is a diagram illustrating various aberrations in the infinite focus state in the fourth example and a lateral aberration diagram during image stabilization, where (a) is a case in the wide-angle end state and (b) is a case in the intermediate focal length state. , (C) is a case in the telephoto end state. FIG. 9A is a diagram illustrating various aberrations in a close-up shooting distance state in the fourth embodiment and a lateral aberration diagram during image stabilization. FIG. 10A is a case in the wide-angle end state, and FIG. Yes, (c) is in the telephoto end state. FIG. 10 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 5, where (W) is a wide-angle end state in an infinite focus state, (M) is an intermediate focal length state in an infinite focus state, and (T ) Shows the telephoto end state at the infinity in-focus state. FIG. 10 is a diagram illustrating various aberrations in the infinitely focused state and a lateral aberration diagram during image stabilization in the fifth example, where (a) is a case in the wide-angle end state and (b) is a case in the intermediate focal length state. , (C) is a case in the telephoto end state. FIG. 9A is a diagram illustrating various aberrations in a close-up shooting distance focus state in the fifth embodiment and a lateral aberration diagram during image stabilization. FIG. 10A is a case in the wide-angle end state, and FIG. Yes, (c) is in the telephoto end state. FIG. 10 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 6, where (W) is a wide-angle end state in an infinite focus state, (M) is an intermediate focal length state in an infinite focus state, and (T ) Shows the telephoto end state at the infinity in-focus state. FIG. 10 is a diagram illustrating various aberrations in the infinite focus state in the sixth example and a lateral aberration diagram during image stabilization, where (a) is a case in the wide-angle end state and (b) is a case in the intermediate focal length state. , (C) is a case in the telephoto end state. FIG. 9A is a diagram illustrating various aberrations in the close-up shooting distance state in the sixth embodiment and a lateral aberration diagram during image stabilization. FIG. 10A is a case in the wide-angle end state, and FIG. Yes, (c) is in the telephoto end state.

Explanation of symbols

1 Digital SLR camera (optical equipment)
ZL Zoom lens G1 First lens group G2 Second lens group G3 Third lens group G3F Front group G4 Fourth lens group LPF Low pass filter CG Cover glass S Aperture stop FS Field stop I Image surface

Claims (13)

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, arranged in order from the object side along the optical axis; The fourth lens group having refractive power substantially consists of four lens groups,
When zooming from the wide-angle end state to the telephoto end state in the infinite focus state, the first lens group and the third lens group are moved to the object side, and the second lens group is concave on the object side. The fourth lens group is moved along the optical axis along a locus convex toward the object side, and moved along the optical axis along a locus.
The third lens group includes a positive lens L31 arranged in order from the object side, a negative meniscus lens L32 having a convex surface facing the object side, a front lens group G3F having a positive refractive power and a positive lens L33, and a convex surface facing the object side. A negative meniscus lens L34 facing
One of the three surfaces of the object side and image side lens surfaces of the positive lens L31 and the object side lens surface of the negative meniscus lens L32 is an aspheric surface,
Any one of the three surfaces of the image side lens surface of the positive lens L33 and the object side and image side lens surfaces of the negative meniscus lens L34 is an aspheric surface,
Assuming that the focal length of the third lens group is f30 and the focal length of the negative meniscus lens L34 is f34, the following equation −0.6 <f30 / f34 <−0.1
A zoom lens that satisfies the following conditions.   The radius of curvature of the image side lens surface of the negative meniscus lens L32 and the radius of curvature of the object side lens surface of the positive lens L33 are smaller than those of the other lens surfaces constituting the third lens group. The zoom lens according to claim 1.   The zoom lens according to claim 1 or 2, wherein in the third lens group, the negative meniscus lens L32 and the positive lens L33 are bonded to form a cemented lens. When the focal length of the front lens group in the third lens group is fG3F, the focal length of the negative meniscus lens L34 is f34, and the average refractive index N3n of the negative meniscus lens L32 and the negative meniscus lens L34 is Formula −0.24 <fG3F / (f34 × N3n) <− 0.05
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition. When the wide-angle end focal length of the entire lens system is Fw, the focal length of the third lens group is f30, and the telephoto end focal length of the entire lens system is Ft, 0.03 <(Fw × f30) / Ft ² <0.08
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition. When the thickness on the optical axis of the positive lens L33 is d33, and the thickness on the optical axis of the third lens group is d30, the following expression 0.28 <d33 / d30 <0.60
The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.   The zoom lens according to claim 1, wherein image blur correction is performed by moving the front group of the third lens group in a direction perpendicular to the optical axis.   8. The flare-cut stop is disposed between the image side lens surface of the positive lens L <b> 33 and the object side lens surface of the negative meniscus lens L <b> 34 in the third lens group. The zoom lens according to claim 1.   The zoom lens according to claim 1, wherein image blur correction is performed by moving the second lens group in a direction perpendicular to the optical axis.   10. The zoom lens according to claim 9, wherein flare-cut stops are respectively disposed on the object side and the image side of the second lens group. The fourth lens group is a positive meniscus lens having a convex surface directed toward the object side, claim photographing object is and moving toward the object side along the optical axis when focusing at a finite distance 1-10 The zoom lens according to any one of the above. An optical apparatus comprising the zoom lens according to any one of claims 1 to 11 . 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, arranged in order from the object side along the optical axis; An image forming method for forming an image of the object on a predetermined image plane by using a zoom lens composed of substantially four lens groups with a fourth lens group having refractive power,
When zooming from the wide-angle end state to the telephoto end state in the infinite focus state, the first lens group and the third lens group are moved to the object side, and the second lens group is concave on the object side. The fourth lens group is moved along the optical axis along a locus convex toward the object side, and moved along the optical axis along a locus.
The third lens group includes a positive lens L31 arranged in order from the object side, a negative meniscus lens L32 having a convex surface facing the object side, a front lens group G3F having a positive refractive power and a positive lens L33, and a convex surface facing the object side. A negative meniscus lens L34 facing
One of the three surfaces of the object side and image side lens surfaces of the positive lens L31 and the object side lens surface of the negative meniscus lens L32 is an aspheric surface,
Any one of the three surfaces of the image side lens surface of the positive lens L33 and the object side and image side lens surfaces of the negative meniscus lens L34 is an aspheric surface,
Assuming that the focal length of the third lens group is f30 and the focal length of the negative meniscus lens L34 is f34, the following equation −0.6 <f30 / f34 <−0.1
An imaging method characterized by satisfying the following condition.

Images