JP5257734B2 - 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 and a four-group configuration has been proposed (see, for example, Patent Documents 1 to 3).

JP 2004-212616 A JP 2004-94233 A JP 2006-308957 A

  However, in the zoom lenses of Patent Documents 1 and 2, the zoom ratio is only about 4 times while the shooting angle of view at the wide angle end is about 35 °. The zoom lens disclosed in Patent Document 3 has a wide shooting angle of view, but the total length of the lens is large with respect to the focal length at the wide-angle end. There was a problem that.

  The present invention has been made in view of such problems, and has a zoom ratio and a zoom lens that have excellent optical performance, a large zoom ratio, a wide angle of view at the wide-angle end, and a short total lens length. 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 four lens groups, and the first lens groups are arranged in order from the object side. , a negative meniscus lens L11 having a convex surface directed toward the object side and a positive lens L12, the second lens group, in order from the object, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens and L22, and a positive lens L23 Prefecture, the negative meniscus lens L21 in the second lens group to the object side lens surface an aspherical, the positive lens L23 in the second lens group on the object side and image side lens surface U Characterized by the any one aspherical surface.

In the zoom lens according to the present invention, when the focal length of the first lens group is F1, and the focal length of the second lens group is F2, the following expression -0.15 <F2 / F1 <-0. It satisfies the condition of 05 .

In a zoom lens system according to the present invention, the focal length of the fourth lens group when the F4, characterized in that the following conditional expression is satisfied: 0.57 <F4 / F1 <1.30.

  Further, when the refractive index of the negative meniscus lens L11 of the first lens group is N11, it is preferable that the condition of the following expression 1.85 <N11 <2.30 is satisfied.

  The first lens group includes a cemented lens obtained by bonding the negative meniscus lens L11 and the positive lens L12, and the second lens group includes the negative meniscus lens L21, the biconcave lens L22, and the positive lens. It is preferable that all the lenses L23 are constituted by a single lens.

  Further, in the positive lens L12 of the first lens group, when the radius of curvature of the object side lens surface is R12F and the radius of curvature of the image side lens surface is R12I, the following formula −0.15 <R12F / R12I <0 It is preferable to satisfy the condition of .25.

  Further, in the positive lens L23 of the second lens group, when the radius of curvature of the object side lens surface is R23F and the radius of curvature of the image side lens surface is R23I, the following expression −0.15 <R23F / R23I <0 It is preferable that the condition of .30 is satisfied.

The third lens group includes a front lens group arranged in order from the object side, a front lens group having a positive refractive power, which includes a positive lens L31, a negative meniscus lens L32 having a convex surface facing the object side, and a positive lens L33; it is preferable that the negative meniscus lens L34 having a convex surface facing the.

The fourth lens group includes a positive lens in which the absolute value of the radius of curvature of the object side lens surface is smaller than the absolute value of the radius of curvature of the image side lens surface, and the object side lens surface is convex toward the object side. When focusing from an infinitely distant object to a close object, it is preferable to move the object side along the optical axis.

  Further, when zooming from a wide-angle focal length to a telephoto focal length in an 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 to the object side. It is preferable that the fourth lens unit is moved along the optical axis along a locus convex toward the object side.

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

In addition, the imaging method of the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power arranged in order from the object side along the optical axis. The image of the object is formed on a predetermined image plane by using a zoom lens that is substantially composed of four lens groups, with a third lens group having a fourth lens group having a positive refractive power. a focusing method, the first lens group, in order from the object, a negative meniscus lens L11 having a convex surface directed toward the object side and a positive lens L12, the second lens group includes, in order from an object side from arranged in a forward, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, and a positive lens L23 Prefecture, the negative meniscus lens L21 in the second lens group and the aspherical surface of the object-side lens surface And the second lens The positive lens L23 is any one surface of the object side and the image side lens surface is an aspherical surface, the focal length of the first lens group and F1, the focal length of the second lens group and the F2 in When the following expression −0.15 <F2 / F1 <−0.05 is satisfied and the focal length of the fourth lens group is F4, the following expression 0.57 <F4 / F1 <1.30 is satisfied. It satisfies the conditions .

  As described above, according to the present invention, a zoom lens having an excellent optical performance, a large zoom ratio, a large angle of view and a short total lens length in a wide-angle end state, and an optical device equipped with the zoom lens And an imaging method can be provided.

  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.

  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. It is preferable to adopt a so-called telephoto type lens configuration including the 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.

  Further, the third lens group G3 can adjust the Seidel 5 aberration correction by making the front group G3F a positive / negative / positive triplet structure. ) Is more preferable in terms of aberration correction because aberration correction of field curvature can be further improved.

  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, the fourth lens group G4 is a positive lens in which the absolute value of the radius of curvature of the object side lens surface is smaller than the absolute value of the radius of curvature of the image side lens surface, and the object side lens surface is convex toward the object side. It is preferable to have a configuration. 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. .

  Although the zoom lens ZL is a high-magnification optical system, zooming from the wide-angle end state to the telephoto end state at infinity is performed in order to shorten the overall lens length when the lens barrel is stored (magnification). 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.

  In the zoom lens ZL configured as described above, when the focal length of the first lens group G1 is F1 and the focal length of the second lens group G2 is F2, it is preferable that the following expression (1) is satisfied.

    −0.15 <F2 / F1 <−0.05 (1)

  Conditional expression (1) defines an appropriate ratio between the focal length F1 of the first lens group G1 and the focal length F2 of the second lens group G2. In conditional expression (1), if the value falls below the lower limit, chromatic aberration at the telephoto end increases, which is not preferable. On the other hand, if the upper limit is exceeded in conditional expression (1), the field curvature at the wide-angle end becomes negatively large, which is not preferable. Further, the variation of spherical aberration due to zooming becomes large, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to −0.14. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to −0.07.

  In the zoom lens ZL, when the focal length of the first lens group G1 is F1 and the focal length of the fourth lens group G4 is F4, it is preferable that the following expression (2) is satisfied.

    0.57 <F4 / F1 <1.30 (2)

  Conditional expression (2) defines an appropriate ratio between the focal length F1 of the first lens group G1 and the focal length F4 of the fourth lens group G4. In conditional expression (2), if the value is below the lower limit, chromatic aberration at the telephoto end increases, which is not preferable. On the other hand, if the upper limit is exceeded in conditional expression (2), the field curvature at the wide angle end becomes negatively large, which is not preferable. Also, the variation of spherical aberration accompanying zooming (magnification) increases, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.60. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 1.10.

  Further, in the zoom lens ZL, in order to reduce the total thickness of the first lens group G1 in order to shorten the lens length (at the wide angle end), the refractive index of the glass used for the first lens group G1 is increased to increase the lens surface. What is necessary is just to enlarge a curvature radius. At this time, in order to enable favorable aberration correction, it is preferable that the following expression (3) is satisfied when the refractive index of the negative meniscus lens L11 of the first lens group G1 is N11.

    1.85 <N11 <2.30 (8)

  Conditional expression (3) defines an appropriate range of the refractive index N11 of the negative meniscus lens L11 of the first lens group G1. In conditional expression (3), if the lower limit value is not reached, it is difficult to correct spherical aberration in the first lens group G1 while the total lens thickness is kept thin, which is not preferable. On the other hand, if the upper limit value is exceeded in conditional expression (3), chromatic aberration becomes large at the telephoto end, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to 1.88. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to 2.15.

  In the zoom lens ZL, in the positive lens L12 of the first lens group G1, when the radius of curvature of the object side lens surface is R12F and the radius of curvature of the image side lens surface is R12I, the following expression (4) is satisfied. It is preferable.

    -0.15 <R12F / R12I <0.25 (4)

  Conditional expression (4) defines an appropriate ratio between the object-side radius of curvature R12F and the image-side radius of curvature R12I of the lens surface constituting the positive lens L12 of the first lens group G1. In conditional expression (4), if the value is below the lower limit, the field curvature at the wide-angle end increases toward the negative side, which is not preferable. On the other hand, if this conditional expression (4) exceeds the upper limit value, the chromatic aberration at the telephoto end increases, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to −0.13. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 0.23.

  In the zoom lens ZL, in the positive lens L23 of the second lens group G2, when the radius of curvature of the object side lens surface is R23F and the radius of curvature of the image side lens surface is R23I, the following expression (5) is satisfied. It is preferable.

    -0.15 <R23F / R23I <0.30 (5)

  Conditional expression (5) defines an appropriate ratio between the object-side radius of curvature R23F and the image-side radius of curvature R23I of the lens surface constituting the positive lens L23 of the second lens group G2. In conditional expression (5), if the value is below the lower limit, the field curvature at the wide-angle end increases toward the negative side, which is not preferable. On the other hand, if this conditional expression (5) exceeds the upper limit, the chromatic aberration at the telephoto end increases, which is not preferable. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to −0.14. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 0.27.

  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 in which the object side lens surface is stronger on the object side than the image side lens surface.

  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 5 are shown below, but these are tables of specifications in the first to fifth 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 d-line (wavelength 587.6 nm), and νd is the Abbe number with respect to d-line. In the table, values corresponding to the conditional expressions (1) to (5) 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) F2 / F1 = 0.109
(2) F4 / F1 = 0.748
(3) N11 = 1.904
(4) R12F / R12R = 0.099
(5) R23F / R23R = 0.047

  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 (5).

  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. The surface numbers 1 to 24 in Table 2 correspond to the surfaces 1 to 24 shown in FIG. In the second 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 2)
[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 -14.53 to -7.50
[Lens specifications]
Surface number r d nd νd
1 40.6412 0.8000 2.000690 25.46
2 28.2157 3.0000 1.696800 55.52
3 -248.3988 (d3 = variable)
4 * 20.3283 0.7000 1.851350 40.10
5 4.7773 3.0000
6 -7.1182 0.6000 1.755000 52.29
7 15.3756 0.3000
8 8.7760 1.4000 1.821140 24.06
9 * -67.1622 (d9 = variable)
10 Aperture stop S 0.3000
11 * 4.3306 1.5000 1.768020 49.23
12 8.1228 0.1000
13 6.7870 0.8000 1.903660 31.31
14 2.6931 2.9000 1.592010 67.05
15 * -17.9542 0.3000
16 Flare cut aperture FS 0.7000
17 18.1191 0.6000 1.883000 40.77
18 10.8949 (d18 = variable)
19 15.5342 1.1000 1.516800 64.12
20 31.5412 (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 = 8.7918, A4 = 8.15820E-05, A6 = -2.43020E-06, A8 = 0.00000E + 00, A10 = 0.00000E + 00
9th page
K = -100.0000, A4 = 4.68610E-04, A6 = 2.25190E-05, A8 = -1.70990E-06, A10 = 9.88520E-08
11th page
K = -0.1603, A4 = -2.51830E-04, A6 = 4.91790E-06, A8 = 0.00000E + 00, A10 = 0.00000E + 00
15th page
K = -49.4719, A4 = 7.76570E-04, A6 = 1.28900E-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 ∞ ∞ ∞ 94.7476 274.2695 534.7786
d3 2.13790 14.42833 24.00163 2.13790 14.42833 24.00163
d9 7.18427 1.67597 0.43506 7.18427 1.67597 0.43506
d18 3.36244 2.29010 13.14988 2.14708 0.59515 9.45961
d20 2.79157 10.64603 8.11865 4.00693 12.34099 11.80892
Bf 0.40633 0.40633 0.40633 0.40633 0.40633 0.40633
TL 35.78251 49.34677 66.01157 35.78251 49.34677 66.01157
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 60.00000
G2 4 -5.45518
G3 11 7.64811
G4 19 57.87425
[Conditional expression]
(1) F2 / F1 = -0.091
(2) F4 / F1 = 0.965
(3) N11 = 2.001
(4) R12F / R12R = -0.114
(5) R23F / R23R = -0.131

  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 (5).

  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 shows the case of the wide angle end state (F = 5.20 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 = 130 mm). FIG. 7B shows the case of the intermediate focal length state (Rm = 324 mm), and FIG. 7C shows the case of the telephoto end state (Rt = 601 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 5.20 to 15.00 to 35.00
FNO 3.0 to 4.4 to 6.1
ω -39.32 to -14.76 to -7.66
[Lens specifications]
Surface number r d nd νd
1 21.7945 0.8000 1.902000 25.10
2 16.1307 3.4000 1.617200 54.00
3 143.7476 (d3 = variable)
4 * 20.0988 0.7000 1.851350 40.10
5 4.8159 3.0000
6 -7.0561 0.6000 1.755000 52.29
7 15.9179 0.3000
8 6.9706 1.4000 1.821140 24.06
9 * 69.0406 (d9 = variable)
10 Aperture stop S 0.3000
11 * 4.7796 1.5000 1.768020 49.23
12 12.8665 0.1000
13 7.8084 0.8000 1.903660 31.31
14 2.9041 2.9000 1.592010 67.05
15 * -20.5387 0.3000
16 Flare cut aperture FS 0.7000
17 13.1655 0.6000 1.883000 40.77
18 7.6286 (d18 = variable)
19 10.9258 1.1000 1.516800 64.12
20 24.3105 (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 = 11.0079, A4 = 2.14710E-04, A6 = -2.42160E-06, A8 = 0.00000E + 00, A10 = 0.00000E + 00
9th page
K = -100.0000, A4 = 1.03330E-03, A6 = 6.02490E-05, A8 = -6.60540E-06, A10 = 3.26160E-07
11th page
K = -0.4939, A4 = 1.79000E-04, A6 = 1.98550E-05, A8 = 0.00000E + 00, A10 = 0.00000E + 00
15th page
K = -100.0000, A4 = 3.24000E-04, A6 = 1.54670E-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 ∞ ∞ ∞ 94.3369 275.0159 628.5204
d3 0.72531 12.13516 22.53601 0.72531 12.13516 22.53601
d9 7.93142 2.20666 0.64475 7.93142 2.20666 0.64475
d18 3.15712 1.81415 11.91646 2.32385 0.55617 8.91987
d20 2.90657 9.93463 8.67126 3.73984 11.19261 11.66785
Bf 0.40631 0.40631 0.40631 0.40631 0.40631 0.40631
TL 35.42673 46.79692 64.47478 35.42673 6.79692 64.47478
[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) F2 / F1 = 0.109
(2) F4 / F1 = 0.748
(3) N11 = 1.902
(4) R12F / R12R = 0.112
(5) R23F / R23R = 0.101

  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 (5).

  FIG. 9 is a diagram of various aberrations in the infinitely focused state and lateral aberration diagram at the time of image stabilization in the third example, and FIG. 9A shows the case of the wide-angle end state (F = 5.20 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 = 35.00 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 = 693 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 29.75
FNO 3.0 to 4.4 to 6.1
ω -39.32 to -14.68 to -7.54
[Lens specifications]
Surface number r d nd νd
1 22.5789 0.8000 1.922860 20.88
2 17.2074 3.4000 1.754999 52.32
3 76.8562 (d3 = variable)
4 * 21.0921 0.7000 1.851350 40.10
5 4.8000 3.0000
6 -7.5984 0.6000 1.755000 52.29
7 16.2867 0.3000
8 6.1060 1.4000 1.821140 24.06
9 * 24.9329 (d9 = variable)
10 Aperture stop S 0.3000
11 * 5.3286 1.5000 1.768020 49.23
12 13.9187 0.1000
13 6.5274 0.8000 1.903660 31.31
14 2.8407 2.9000 1.592010 67.05
15 * -19.0700 0.3000
16 Flare cut aperture FS 0.7000
17 17.8368 0.6000 1.883000 40.77
18 7.3901 (d18 = variable)
19 23.7123 1.1000 1.516800 64.12
20 -45.6751 (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 = 11.3059, A4 = 2.78670E-04, A6 = -3.58790E-06, A8 = 0.00000E-00, A10 = 0.00000E-00
9th page
K = -100.0000, A4 = 2.06190E-03, A6 = 3.69370E-05, A8 = -6.44020E-06, A10 = 3.26430E-07
11th page
K = -1.1345, A4 = 6.83490E-04, A6 = 1.95820E-05, A8 = 0.00000E-00, A10 = 0.00000E-00
15th page
K = -100.0000, A4 = -1.46160E-04, A6 = 9.38390E-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 ∞ ∞ ∞ 94.3705 275.0340 550.8531
d3 0.59589 11.48771 18.95438 0.59589 11.48771 18.95438
d9 8.55530 2.69871 1.00060 8.55530 2.69871 1.00060
d18 2.23474 0.85659 4.67160 1.53591 -0.26215 2.70122
d20 3.70791 10.12128 12.07483 4.40674 11.24002 14.04521
Bf 0.40631 0.40631 0.40631 0.40631 0.40631 0.40631
TL 35.80015 45.87061 57.40770 35.80015 45.87061 57.40770
[Zoom lens group data]
Group number Group first surface Group focal length G1 1 45.00000
G2 4 -5.45518
G3 11 7.92074
G4 19 30.36698
[Conditional expression]
(1) F2 / F1 = -0.121
(2) F4 / F1 = 0.675
(3) N11 = 1.923
(4) R12F / R12R = 0.224
(5) R23F / R23R = 0.245

  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 (5).

  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 and lateral aberration diagram at the time of image stabilization in the fourth embodiment. FIG. 13A is a wide-angle end state (Rw = 130 mm). FIG. 13B shows the case of the intermediate focal length state (Rm = 321 mm), and FIG. 13C shows the case of the telephoto end state (Rt = 608 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 35.00
FNO 3.0 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) F2 / F1 = -0.108
(2) F4 / F1 = 0.661
(3) N11 = 1.904
(4) R12F / R12R = 0.096
(5) R23F / R23R = 0.038

  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 (5).

  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).

  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.

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 (10)

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 ,
Wherein the first lens group, in order from the object, a negative meniscus lens L11 having a convex surface directed toward the object side and a positive lens L12,
The second lens group, in order from the object, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, and a positive lens L23 Prefecture,
The negative meniscus lens L21 in the second lens group has an aspheric object side lens surface,
The positive lens L23 in the second lens group has one aspheric surface on the object side and the image side lens surface ,
When the focal length of the first lens group is F1, and the focal length of the second lens group is F2, the following formula
−0.15 <F2 / F1 <−0.05
Satisfy the conditions of
When the focal length of the fourth lens group is F4,
0.57 <F4 / F1 <1.30
A zoom lens that satisfies the following conditions . When the refractive index of the negative meniscus lens L11 of the first lens group is N11, the following expression 1.85 <N11 <2.30
The zoom lens according to claim 1 , wherein the following condition is satisfied. The first lens group includes a cemented lens in which the negative meniscus lens L11 and the positive lens L12 are bonded together.
The second lens group, the zoom lens according to claim 1 or 2, characterized in that configured in said negative meniscus lens L21 and the biconcave lens L22 and the all positive lenses L23 single lens. In the positive lens L12 of the first lens group, when the radius of curvature of the object side lens surface is R12F and the radius of curvature of the image side lens surface is R12I, the following expression −0.15 <R12F / R12I <0.25
The zoom lens according to any one of claims 1 to 3, characterized by satisfying the condition. In the positive lens L23 of the second lens group, when the curvature radius of the object side lens surface is R23F and the curvature radius of the image side lens surface is R23I, the following expression −0.15 <R23F / R23I <0.30
The zoom lens according to any one of claims 1 to 4, characterized by satisfying the condition. The third lens group includes, in order from the object side, a positive lens L31, a negative meniscus lens L32 having a convex surface facing the object side, a positive lens L33 and a front group having positive refractive power, and a convex surface facing the object side. the zoom lens according to any one of claims 1 to 5, characterized in that a negative meniscus lens L34 having a. The fourth lens group, the absolute value of the curvature radius of the object-side lens surface is smaller than the absolute value of the curvature radius of the image side lens surface and the object-side lens surface and a positive lens that is convex toward the object side, endless the zoom lens according to any one of claims 1 to 6, characterized in that moving the object along the optical axis when focusing from a far object to a close object. When zooming from a wide-angle focal length to a telephoto focal length in an 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. of moving along the optical axis at the locus, according to any one of claims 1 to 7 fourth lens unit, characterized in that moving along the optical axis at a convex locus toward the object side Zoom lens. An optical apparatus comprising the zoom lens according to any one of claims 1 to 8 . 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,
Wherein the first lens group, in order from the object, a negative meniscus lens L11 having a convex surface directed toward the object side and a positive lens L12,
The second lens group, in order from the object, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, and a positive lens L23 Prefecture,
The negative meniscus lens L21 in the second lens group has an aspheric object side lens surface,
The positive lens L23 in the second lens group has one aspheric surface on the object side and the image side lens surface ,
When the focal length of the first lens group is F1, and the focal length of the second lens group is F2, the following formula
−0.15 <F2 / F1 <−0.05
Satisfy the conditions of
When the focal length of the fourth lens group is F4,
0.57 <F4 / F1 <1.30
An imaging method characterized by satisfying the following condition .

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