JP6467769B2 - Zoom lens and optical device - Google Patents

Description

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

  In recent years, a thin zoom lens has been proposed (see, for example, Patent Document 1).

JP 2010-044190 A

  Zoom lenses are expected to be thinner than conventional lenses.

The present invention has been made in view of such problems, and an object thereof is to provide a zoom lens and an optical apparatus which are thin and have excellent optical performance.

In order to achieve such an object, a zoom lens according to a first aspect of the present invention includes a first lens group having a positive refractive power arranged in order from the object side along the optical axis, and a first lens group having a negative refractive power. From five lens groups by two lens groups, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power. Thus, at the time of zooming, all the lens groups move on the optical axis, and the distance between the lens groups changes. The first lens group is composed of two lenses, and the second lens group is located on the object side. The third lens group is composed of a negative lens, a negative lens, and a positive lens arranged in order from the object side, and the third lens group is arranged in order from the object side, a cemented lens of a positive lens and a negative lens, and a positive lens in the configuration, the fourth lens group is composed of one negative lens, the fifth lens group, 1 The distance on the optical axis from the most object side surface to the image plane of the fifth lens group is larger in the telephoto end state than in the wide-angle end state, and the second lens group and the third lens An aperture stop is disposed between the zoom lens unit and the aperture stop. The aperture stop moves on the optical axis together with the third lens unit during zooming, and satisfies the following conditional expression.

0.07 <D1 / fw < ≦ 0.134
Or
0.454 ≦ D1 / fw <0.46
However,
D1: thickness of the first lens group on the optical axis;
fw: focal length of the zoom lens in the wide-angle end state.

A zoom lens according to a second aspect of the 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. A third lens group having a negative refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power, and substantially consisting of five lens groups. Moves on the optical axis and the interval between the lens groups changes, and the first lens group is composed of a cemented lens composed of a negative lens and a positive lens arranged in order from the object side, and the third lens The group is composed of a positive lens, a cemented lens of a positive lens and a negative lens, and a positive lens arranged in order from the object side, and an aperture stop is disposed between the second lens group and the third lens group. is, the aperture stop, on the optical axis to move together with the third lens group during zooming, the following conditions To satisfy.

0.07 <D1 / fw <0.46
0.23 <(TL5-WL5) /ft≦0.323
However,
D1: thickness of the first lens group on the optical axis;
fw: focal length of the zoom lens in the wide-angle end state;
WL5: distance on the optical axis from the most object side surface to the image plane of the fifth lens group in the wide-angle end state;
TL5: distance on the optical axis from the most object side surface to the image plane of the fifth lens group in the telephoto end state;
ft: focal length of the zoom lens in the telephoto end state.

A zoom lens according to a third aspect 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. A third lens group having a negative refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power, and substantially consisting of five lens groups. Moving on the optical axis, the interval between each lens group changes, the first lens group is composed of two lenses, the third lens group is arranged in order from the object side, a positive lens, a cemented lens of a positive lens and a negative lens, a positive lens, the fifth lens group is composed of one positive lens, an aperture stop between the second lens group and the third lens group There is arranged, the aperture stop, on the optical axis to move together with the third lens group during zooming, the following condition To foot.

0.07 <D1 / fw <0.46
0.23 <(TL5-WL5) /ft≦0.323
However,
D1: thickness of the first lens group on the optical axis;
fw: focal length of the zoom lens in the wide-angle end state;
WL5: distance on the optical axis from the most object side surface to the image plane of the fifth lens group in the wide-angle end state;
TL5: distance on the optical axis from the most object side surface to the image plane of the fifth lens group in the telephoto end state;
ft: focal length of the zoom lens in the telephoto end state.

  The optical apparatus according to the present invention includes any one of the above zoom lenses.

According to the present invention, it is possible to provide a zoom lens and an optical apparatus that are thin and have excellent optical performance.

FIG. 2 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 1, where (W) indicates a wide-angle end state, (M) indicates an intermediate focal length state, and (T) indicates a position of each lens group in a telephoto end state. FIG. 6 is a diagram illustrating various aberrations of the zoom lens according to Example 1, where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is an aberration diagram at an imaging distance infinite at a telephoto end state. is there. FIG. 6 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 2, where (W) indicates a wide-angle end state, (M) indicates an intermediate focal length state, and (T) indicates a position of each lens group in a telephoto end state. FIG. 6 is a diagram illustrating various aberrations of the zoom lens according to Example 2, where (a) illustrates various aberrations at the wide-angle end state, (b) illustrates an intermediate focal length state, and (c) illustrates various aberrations at an imaging distance of infinity in the telephoto end state. is there. FIG. 6 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 3, where (W) indicates a wide-angle end state, (M) indicates an intermediate focal length state, and (T) indicates a position of each lens group in a telephoto end state. FIG. 7A is a diagram illustrating various aberrations of the zoom lens according to Example 3, where FIG. 9A is a diagram illustrating various aberrations at an infinite shooting distance in the wide-angle end state, FIG. is there. (A) is a front view of a digital still camera, (b) is a rear view of a digital still camera. It is sectional drawing along arrow AA 'in Fig.7 (a). It is a flowchart which shows the manufacturing method of a zoom lens.

  Hereinafter, embodiments will be described with reference to the drawings. As shown in FIG. 1, the zoom lens ZL according to the present embodiment includes a first lens group G1 having a positive refractive power and a second lens having a negative refractive power, which are arranged in order from the object side along the optical axis. A wide-angle end state having a lens group G2, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power During zooming from the zoom position to the telephoto end state, the distance between the lens groups changes, and the first lens group G1 is composed of two lenses, and satisfies the following conditional expression (1).

0.07 <D1 / fw <0.46 (1)
However,
D1: Thickness on the optical axis of the first lens group G1,
fw: focal length of the zoom lens ZL in the wide-angle end state.

  As described above, the zoom lens ZL according to the present embodiment can satisfactorily correct fluctuations in the image plane position due to zooming due to the configuration in which the distance between the lens groups changes during zooming.

  Conditional expression (1) defines the thickness of the first lens group G1. By satisfying conditional expression (1), it is possible to reduce the spherical aberration, astigmatism and lateral chromatic aberration while reducing the thickness of the optical system. If the upper limit of conditional expression (1) is exceeded, the amount of movement due to zooming of the second lens group G2 and the third lens group G3 cannot be secured, and the refractive power of the second lens group G2 and the third lens group G3 is strengthened. Therefore, it is difficult to suppress the variation of spherical aberration and astigmatism due to zooming. If the lower limit of conditional expression (1) is not reached, the amount of lateral chromatic aberration and spherical aberration occurring in the first lens group G1 will increase, and it will be difficult to satisfactorily correct lateral chromatic aberration and spherical aberration, particularly in the telephoto end state. Become.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.09. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.11. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.13.

  In the zoom lens ZL according to the present embodiment, it is preferable that all the lens groups move on the optical axis during zooming. With this configuration, it is possible to satisfactorily correct fluctuations in the image plane position while reducing the diameter of the first lens group G1.

  In the zoom lens ZL according to the present embodiment, it is preferable that the distance from the most object side surface to the image surface of the fifth lens group G5 is larger in the telephoto end state than in the wide angle end state. With this configuration, it is possible to suppress variations in the exit pupil due to zooming. If the distance from the most object side surface of the fifth lens group G5 to the image plane is smaller in the telephoto end state than in the wide-angle end state, it is possible to suppress fluctuations in the exit pupil by moving other groups. However, in this case, it is difficult to suppress fluctuations in the image plane position.

  The zoom lens ZL according to the present embodiment preferably satisfies the following conditional expression (2).

0.23 <(TL5-WL5) / ft <1.20 (2)
However,
WL5: distance on the optical axis from the most object side surface to the image plane of the fifth lens group G5 in the wide-angle end state;
TL5: distance on the optical axis from the most object side surface to the image plane of the fifth lens group G5 in the telephoto end state;
ft: focal length of the zoom lens ZL in the telephoto end state.

  Conditional expression (2) defines the amount of movement of the fifth lens group G5 from the wide-angle end state to the telephoto end state and the moving direction (movement toward the object side). By satisfying conditional expression (2), the variation of the exit pupil due to field curvature and zooming can be reduced. If the upper limit value of conditional expression (2) is exceeded, the curvature of field increases, making it difficult to obtain a flat image surface. If the lower limit value of conditional expression (2) is not reached, the curvature of field becomes good, but the fluctuation of the exit pupil becomes too large. Here, if another lens group is moved in order to suppress the fluctuation of the exit pupil, it is difficult to suppress the fluctuation of the image plane position, which is not preferable because the lens becomes large.

  In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 1.00. In order to secure the effect of the present embodiment, it is preferable to set the upper limit value of conditional expression (2) to 0.80. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.60.

  In the zoom lens ZL according to the present embodiment, the first lens group G1 is preferably composed of a negative lens and a positive lens arranged in order from the object side. With this configuration, it is possible to satisfactorily correct spherical aberration generated in the first lens group G1 while reducing the diameter of the first lens group G1.

  In the zoom lens ZL according to this embodiment, the first lens group G1 is preferably composed of a cemented lens including the two lenses. With this configuration, it is possible to satisfactorily correct lateral chromatic aberration generated in the first lens group G1 while reducing the thickness of the first lens group G1 on the optical axis.

  In the zoom lens ZL according to the present embodiment, the second lens group G2 is preferably composed of a negative lens, a negative lens, and a positive lens arranged in order from the object side. With this configuration, it is possible to satisfactorily correct astigmatism variation due to zooming.

  According to the zoom lens ZL according to the present embodiment having the above-described configuration, a zoom lens that is thin and has excellent optical performance can be realized.

  7 and 8 show the configuration of a digital still camera CAM (optical device) as an optical device including the above-described zoom lens ZL. In this digital still camera CAM, when a power button (not shown) is pressed, a shutter (not shown) of the photographing lens (zoom lens ZL) is opened, and light from the subject (object) is condensed by the zoom lens ZL, and an image is displayed. An image is formed on an image sensor C (for example, a CCD or a CMOS) disposed on the surface I (see FIG. 1). The subject image formed on the image sensor C is displayed on the liquid crystal monitor M disposed behind the digital still camera CAM. The photographer determines the composition of the subject image while looking at the liquid crystal monitor M, and then depresses the release button B1 to photograph the subject image with the image sensor C, and records and saves it in a memory (not shown).

  The camera CAM is provided with an auxiliary light emitting unit EF for emitting auxiliary light when the subject is dark, a function button B2 used for setting various conditions of the digital still camera CAM, and the like. Here, a compact type camera in which the camera CAM and the zoom lens ZL are integrally formed is illustrated. However, as an optical device, a single lens reflex camera in which a lens barrel having the zoom lens ZL and a camera body main body can be attached and detached is used. good.

  According to the camera CAM according to the present embodiment having the above-described configuration, a thin camera having excellent optical performance can be realized by mounting the above-described zoom lens ZL as a photographing lens.

  Next, a method for manufacturing the zoom lens ZL will be described with reference to FIG. First, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a positive refractive power in order from the object side along the optical axis. The lenses are arranged so that the group, the fourth lens group having a negative refractive power, and the fifth lens group having a positive refractive power are aligned (step ST10). At this time, the lenses are arranged such that the distance between the lens groups changes during zooming from the wide-angle end state to the telephoto end state (step ST20). In the first lens group G1, each lens is arranged in a lens barrel so as to be composed of two lenses (step ST30). Then, each lens is arranged in the lens barrel so as to satisfy the following conditional expression (1) (step ST40).

0.07 <D1 / fw <0.46 (1)
However,
D1: Thickness on the optical axis of the first lens group G1,
fw: focal length of the zoom lens ZL in the wide-angle end state.

  As an example of the lens arrangement in the present embodiment, in the zoom lens ZL shown in FIG. 1, the first lens group G1 having positive refractive power is arranged in order from the object side along the optical axis, and is convex on the object side. A single cemented lens composed of a negative meniscus lens L11 having a convex surface and a positive meniscus lens L12 having a convex surface facing the object side is incorporated in the lens barrel. As the second lens group G2 having negative refractive power, a negative meniscus lens L21 having a convex surface facing the object side from the object side along the optical axis, a biconcave negative lens L22, and a convex surface facing the object side The lenses are assembled in the lens barrel so that the positive meniscus lenses L23 are arranged in this order. As the third lens group G3 having positive refractive power, a positive meniscus lens L31 having a convex surface directed from the object side to the object side along the optical axis, a biconvex positive lens L32, and a biconcave negative lens L33. Each lens is incorporated in the lens barrel so that the two lenses are arranged in this order, and a biconvex positive lens L34. As the fourth lens group G4 having negative refractive power, a biconcave negative lens L41 is incorporated in the lens barrel. As the fifth lens group G5 having positive refractive power, a positive meniscus lens L51 having a convex surface directed toward the object side is incorporated in the lens barrel. Each lens is incorporated in the lens barrel so as to satisfy the conditional expression (1) (corresponding value of the conditional expression (1) is 0.454).

  According to the manufacturing method of the zoom lens ZL described above, it is possible to manufacture a zoom lens that is thin and has excellent optical performance.

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

  In addition, each reference code with respect to FIG. 1 according to the first embodiment is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference code. Therefore, even if the same reference numerals as those in the drawings according to the other embodiments are given, they are not necessarily in the same configuration as the other embodiments.

  In each embodiment, C-line (wavelength 656.2730 nm), d-line (wavelength 587.5620 nm), F-line (wavelength 486.1330 nm), and g-line (wavelength 435.8350 nm) are selected as the aberration characteristic calculation targets.

  In [Lens Specifications] in the table, the surface number is the order of the optical surfaces from the object side along the light traveling direction, R is the radius of curvature of each optical surface, D is the next optical surface from each optical surface ( Or nd is the refractive index of the material of the optical member with respect to the d-line, and νd is the Abbe number based on the d-line of the material of the optical member. The object plane is the object plane, (variable) is the variable plane spacing, the curvature radius “∞” is the plane or aperture, (aperture S) is the aperture stop S, and the image plane is the image plane I. The refractive index of air “1.000000” is omitted. When the optical surface is an aspherical surface, the surface number is marked with *, and the column of curvature radius R indicates the paraxial curvature radius.

In [Aspherical data] in the table, the shape of the aspherical surface shown in [Lens specifications] is shown by the following equation (a). X (y) is the distance along the optical axis direction from the tangential plane at the apex of the aspheric surface to the position on the aspheric surface at height y, R is the radius of curvature of the reference sphere (paraxial radius of curvature), and κ is Ai represents the i-th aspherical coefficient. “E-n” indicates “× 10 ⁻ⁿ ”. For example, 1.234E-05 = 1.234 × 10 ⁻⁵ .

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

  In [Overall specifications] in the table, f is the focal length of the entire lens system, FNo is the F number, ω is the half field angle (maximum incident angle, unit: °), Y is the image height, and Bf is on the optical axis. The distance from the last lens surface to the paraxial image surface in terms of air, TL represents the total lens length (the distance from the foremost lens surface to the last lens surface on the optical axis plus Bf).

  In [ZOOMING DATA] in the table, the variable interval value Di in each state of the wide-angle end, the intermediate focal length, and the telephoto end is shown. Di represents a variable interval between the i-th surface and the (i + 1) -th surface.

  In [Zoom lens group data] in the table, G is the group number, the first group surface is the surface number of the most object side of each group, the group focal length is the focal length of each group, and the lens configuration length is the most object side of each group The distance on the optical axis from the lens surface to the lens surface closest to the image plane is shown.

  [Conditional expression] in the table indicates values corresponding to the conditional expressions (1) and (2).

  Hereinafter, in all the specification values, “mm” is generally used as the focal length f, the radius of curvature R, the surface interval D, and other lengths, etc. unless otherwise specified, but the zoom lens is proportionally enlarged. Alternatively, the same optical performance can be obtained even by proportional reduction, and the present invention is not limited to this. Further, the unit is not limited to “mm”, and other appropriate units can be used.

  The description of the table so far is common to all the embodiments, and the description below is omitted.

(First embodiment)
A first embodiment will be described with reference to FIGS. 1 and 2 and Table 1. FIG. As shown in FIG. 1, the zoom lens ZL (ZL1) according to the first example includes a first lens group G1 having a positive refractive power arranged in order from the object side along the optical axis, and a negative refractive power. A second lens group G2 having 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 negative refractive power, And a fifth lens group G5 having a refractive power of 5 and a filter group FL.

  The first lens group G1 is composed of cemented lenses of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, which are arranged in order from the object side along the optical axis. .

  The second lens group G2 includes, in order from the object side along the optical axis, a negative meniscus lens L21 having a convex surface directed toward the object side, a negative lens L22 having a biconcave shape, and a positive meniscus having a convex surface directed toward the object side. And a lens L23. An aspheric surface is formed on both surfaces of the biconcave negative lens L22.

  The third lens group G3 is composed of a positive meniscus lens L31 arranged in order from the object side along the optical axis and having a convex surface directed toward the object side, and a biconvex positive lens L32 and a biconcave negative lens L33. The lens includes a positive lens L34 having a biconvex shape. An aspheric surface is formed on both surfaces of the positive meniscus lens L31 having a convex surface facing the object side. In addition, an aspherical surface is formed on the image side surface of the biconvex positive lens L34.

  The fourth lens group G4 is composed of a biconcave negative lens L41. Note that aspherical surfaces are formed on both surfaces of the biconcave negative lens L41.

  The fifth lens group G5 includes a positive meniscus lens L51 having a convex surface directed toward the object side.

  The filter group FL is composed of a low-pass filter, an infrared cut filter, or the like for cutting a spatial frequency equal to or higher than the limit resolution of the solid-state imaging device, such as a CCD disposed on the image plane I.

  In the zoom lens ZL1 according to the present embodiment, when changing the magnification from the wide-angle end state to the telephoto end state, the distance between the lens groups changes, and all the lens groups from the first lens group G1 to the fifth lens group G5 are used. Move. Specifically, the first lens group G1 moves to the object side. The second lens group G2 once moves to the image plane side and then moves to the object side. The third lens group G3 moves to the object side. The fourth lens group G4 moves to the object side. The fifth lens group G5 temporarily moves to the object side, and then moves to the image plane side. The aperture stop S moves together with the third lens group G3 toward the object side.

  Table 1 below shows the values of each item in the first example. Surface numbers 1 to 25 in Table 1 correspond to the optical surfaces m1 to m25 shown in FIG.

(Table 1)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 2.7306 0.0728 1.846663 23.78
2 2.0783 0.3813 1.696800 55.52
3 15.1698 D3 (variable)
4 3.7389 0.0607 1.816000 46.59
5 0.6576 0.4915
6 * -2.0572 0.1214 1.618000 63.34
7 * 12.1359 0.0516
8 1.5528 0.1173 1.922860 20.88
9 3.8023 D9 (variable)
10 ∞ 0.0910 (Aperture S)
11 * 1.0879 0.1820 1.697200 53.29
12 * 2.5168 0.0061
13 0.7136 0.1820 1.496997 81.61
14 -2.4934 0.0373 1.903658 31.31
15 1.7027 0.0375
16 2.2109 0.1181 1.593190 67.90
17 * -1.2592 D17 (variable)
18 * -1.1103 0.0910 1.589130 61.22
19 * 12.1359 D19 (variable)
20 2.7306 0.1006 1.593190 67.90
21 6.0680 D21 (variable)
22 ∞ 0.0425 1.516800 63.88
23 ∞ 0.0910
24 ∞ 0.0425 1.516800 63.88
25 ∞ 0.0303
Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10
6 1.0 4.7944E-01 -1.4666E + 00 1.8528E + 00 -1.3866E + 00
7 1.0 4.3981E-01 -1.3992E + 00 1.1351E + 00 0.0000E + 00
11 1.0 5.1446E-01 7.1881E-01 -1.1913E + 00 1.0246E + 01
12 1.0 6.7035E-01 2.8314E-01 0.0000E + 00 0.0000E + 00
17 1.0 7.1443E-01 8.8606E-01 0.0000E + 00 0.0000E + 00
18 1.0 5.1113E + 00 -3.0659E + 01 1.2990E + 02 -3.1106E + 02
19 1.0 4.8193E + 00 -2.3742E + 01 8.5698E + 01 -1.6826E + 02

[Overall specifications]
Zoom ratio 3.305
Wide angle end Intermediate focus Telephoto end f 1.00000 2.12379 3.30461
FNo 3.54324 4.81965 5.66506
ω 42.79279 21.66324 14.26296
Y 0.880 0.880 0.880
Bf 0.85900 1.97261 1.92544
TL 4.882 5.579 6.653

[Zooming data]
Variable interval Wide-angle end Intermediate focus Telephoto end
D3 0.03068 0.77566 1.42774
D9 1.08005 0.30775 0.09204
D17 0.25662 0.15660 0.12136
D19 0.51264 0.22404 0.94421
D21 0.68196 1.79524 1.74808

[Zoom lens group data]
Group number Group first surface Group focal length Lens construction length G1 1 5.10381 0.4541
G2 4 -1.04134 0.8424
G3 11 0.97519 0.6541
G4 18 -1.72232 0.9100
G5 20 8.27662 0.1006

[Conditional expression]
Conditional expression (1) D1 / fw = 0.454
Conditional expression (2) (TL5-WL5) /ft=0.323

  From Table 1, it can be seen that the zoom lens ZL1 according to the present example satisfies the conditional expressions (1) and (2).

  FIG. 2 is a diagram illustrating various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma diagram, and chromatic aberration diagram of magnification) of the zoom lens according to the first example. FIG. 2A is a diagram of various aberrations at an imaging distance of infinity in the wide-angle end state of this embodiment, and FIG. 2B is a graph of various aberrations at an imaging distance of infinity in the intermediate focal length state of this embodiment. FIG. 2C is a diagram showing various aberrations at the photographing distance infinite at the telephoto end state.

  In each aberration diagram, FNO is an F number, and A is a half field angle (unit: °) with respect to each image height. d is the d-line, g is the g-line, C is the C-line, and F is the F-line aberration. Those not described indicate aberrations at the d-line. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. Note that the same reference numerals as in this embodiment are used in the aberration diagrams of each embodiment described later.

  As is clear from the aberration diagrams shown in FIG. 2, it can be seen that the zoom lens ZL1 according to the first example has excellent optical performance with various aberrations corrected well.

(Second embodiment)
A second embodiment, which is a reference example of the present application, will be described with reference to FIGS. As shown in FIG. 3, the zoom lens ZL (ZL2) according to the second example includes a first lens group G1 having a positive refractive power arranged in order from the object side along the optical axis, and a negative refractive power. A second lens group G2 having 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 negative refractive power, And a fifth lens group G5 having a refractive power of 5 and a filter group FL.

  The first lens group G1 is composed of cemented lenses of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, which are arranged in order from the object side along the optical axis. .

  The second lens group G2 includes, in order from the object side along the optical axis, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave negative lens L22, and a positive meniscus having a convex surface facing the object side. And a lens L23. Note that aspherical surfaces are formed on both surfaces of the biconcave negative lens L22.

  The third lens group G3 includes, in order from the object side along the optical axis, a biconvex positive lens L31, a cemented lens of a biconvex positive lens L32, and a biconcave negative lens L33, It is composed of a convex positive lens L34. Note that aspherical surfaces are formed on both surfaces of the biconvex positive lens L31. In addition, an aspherical surface is formed on the image side surface of the biconvex positive lens L34.

  The fourth lens group G4 is composed of a biconcave negative lens L41. Note that aspherical surfaces are formed on both surfaces of the biconcave negative lens L41.

  The fifth lens group G5 includes a positive meniscus lens L51 having a convex surface directed toward the object side.

  The filter group FL is composed of a low-pass filter, an infrared cut filter, or the like for cutting a spatial frequency equal to or higher than the limit resolution of the solid-state imaging device, such as a CCD disposed on the image plane I.

  In the zoom lens ZL2 according to the present embodiment, when changing the magnification from the wide-angle end state to the telephoto end state, the distance between the lens groups is changed, and all the lens groups from the first lens group G1 to the fifth lens group G5 are used. Move. Specifically, the first lens group G1 moves to the object side. The second lens group G2 once moves to the image plane side and then moves to the object side. The third lens group G3 moves to the object side. The fourth lens group G4 moves to the object side. The fifth lens group G5 temporarily moves to the object side, and then moves to the image plane side. The aperture stop S moves together with the third lens group G3 toward the object side.

  Table 2 below shows the values of each item in the second embodiment. Surface numbers 1 to 25 in Table 2 correspond to the optical surfaces m1 to m25 shown in FIG.

(Table 2)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 2.5127 0.0632 1.846663 23.78
2 1.8183 0.3023 1.696800 55.52
3 16.6805 D3 (variable)
4 2.8435 0.0526 1.816000 46.59
5 0.5972 0.4737
6 * -10.5263 0.1053 1.618000 63.34
7 * 1.4871 0.0125
8 1.7750 0.1316 1.922860 20.88
9 8.5638 D9 (variable)
10 ∞ 0.0790 (Aperture S)
11 * 0.9461 0.1842 1.697200 53.29
12 * -16.0370 0.0725
13 1.2079 0.1809 1.496997 81.61
14 -1.5812 0.0316 1.903658 31.31
15 1.6902 0.0940
16 4.1902 0.1316 1.593190 67.90
17 * -1.2873 D17 (variable)
18 * -1.7526 0.0790 1.589130 61.22
19 * 10.5263 D19 (variable)
20 2.3684 0.1547 1.593190 67.90
21 5.2632 D21 (variable)
22 ∞ 0.0368 1.516800 63.88
23 ∞ 0.0790
24 ∞ 0.0368 1.516800 63.88
25 ∞ 0.0303
Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10
6 1.0 -9.4851E-01 2.6113E + 00 -6.0231E + 00 4.0371E + 00
7 1.0 -1.0737E + 00 3.0376E + 00 -8.4959E + 00 9.5788E + 00
11 1.0 7.5212E-02 4.0353E-01 -1.3972E + 00 7.7232E + 00
12 1.0 1.1705E-01 1.9457E-01 -7.6884E-01 4.9478E + 00
17 1.0 6.8208E-01 -1.1266E-01 -4.8349E-01 1.4618E + 01
18 1.0 2.8176E + 00 -1.4255E + 01 3.8274E + 01 -4.2729E + 01
19 1.0 2.5863E + 00 -1.1440E + 01 2.7721E + 01 -2.1578E + 01

[Overall specifications]
Zoom ratio 3.063
Wide angle end Intermediate focus Telephoto end f 1.00000 1.55263 3.06315
FNo 2.87832 4.47291 5.88068
ω 38.77022 25.26713 13.50965
Y 0.763 0.763 0.763
Bf 0.58300 1.51859 2.40412
TL 4.853 5.210 6.282

[Zooming data]
Variable interval Wide-angle end Intermediate focus Telephoto end
D3 0.05065 0.54431 1.25342
D9 1.01510 0.54351 0.15331
D17 0.29027 0.21944 0.10526
D19 0.76589 0.23535 0.21726
D21 0.42908 1.36475 2.25028

[Zoom lens group data]
Group number Group first surface Group focal length Lens construction length G1 1 4.62753 0.3655
G2 4 -0.86259 0.7756
G3 11 1.06779 0.7736
G4 18 -2.54423 0.0790
G5 20 7.11777 0.1547

[Conditional expression]
Conditional expression (1) D1 / fw = 0.365
Conditional expression (2) (TL5-WL5) /ft=0.595

  From Table 2, it can be seen that the zoom lens ZL2 according to the present example satisfies the conditional expressions (1) and (2).

  FIG. 4 is a diagram illustrating various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, coma aberration diagram, and chromatic aberration diagram of magnification) of the zoom lens according to the second example. FIG. 4A is a diagram of various aberrations at an imaging distance of infinity in the wide-angle end state of this embodiment, and FIG. 4B is a graph of various aberrations at an imaging distance of infinity in the intermediate focal length state of this embodiment. FIG. 4C is a diagram showing various aberrations at the photographing distance infinite in the telephoto end state.

  As is clear from the aberration diagrams shown in FIG. 4, it can be seen that the zoom lens ZL2 according to the second example has excellent optical performance with various aberrations corrected well.

(Third embodiment)
A third embodiment will be described with reference to FIGS. As shown in FIG. 5, the zoom lens ZL (ZL3) according to the third example includes a first lens group G1 having a positive refractive power arranged in order from the object side along the optical axis, and a negative refractive power. A second lens group G2 having 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 negative refractive power, And a fifth lens group G5 having a refractive power of 5 and a filter group FL.

  The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, which are arranged in order from the object side along the optical axis.

  The second lens group G2 includes, in order from the object side along the optical axis, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave negative lens L22, and a positive meniscus having a convex surface facing the object side. And a lens L23. An aspheric surface is formed on the image side surface of the negative meniscus lens L21 having a convex surface facing the object side.

  The third lens group G3 is composed of a positive meniscus lens L31 arranged in order from the object side along the optical axis and having a convex surface directed toward the object side, and a biconvex positive lens L32 and a biconcave negative lens L33. The lens includes a positive lens L34 having a biconvex shape. An aspheric surface is formed on both surfaces of the positive meniscus lens L31 having a convex surface facing the object side. In addition, an aspherical surface is formed on the image side surface of the biconvex positive lens L34.

  The fourth lens group G4 is composed of a biconcave negative lens L41. Note that aspherical surfaces are formed on both surfaces of the biconcave negative lens L41.

  The fifth lens group G5 includes a positive meniscus lens L51 having a convex surface directed toward the object side.

  The filter group FL is composed of a low-pass filter, an infrared cut filter, or the like for cutting a spatial frequency equal to or higher than the limit resolution of the solid-state imaging device, such as a CCD disposed on the image plane I.

  In the zoom lens ZL3 according to the present embodiment, the distance between the lens groups changes during zooming from the wide-angle end state to the telephoto end state, and all the lens groups from the first lens group G1 to the fifth lens group G5 are used. Move. Specifically, the first lens group G1 moves to the object side. The second lens group G2 once moves to the image plane side and then moves to the object side. The third lens group G3 moves to the object side. The fourth lens group G4 moves to the object side. The fifth lens group G5 temporarily moves to the object side, and then moves to the image plane side. The aperture stop S moves together with the third lens group G3 toward the object side.

  Table 3 below shows values of various specifications in the third example. Surface numbers 1 to 25 in Table 3 correspond to the optical surfaces m1 to m25 shown in FIG.

(Table 3)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 3.4055 0.0291 1.922860 20.88
2 1.8706 0.1054 1.883000 40.66
3 -8.6752 D3 (variable)
4 4.2131 0.0364 1.816000 46.59
5 0.6642 0.2000
6 * -1.0612 0.0727 1.618000 63.34
7 * 7.2726 0.0364
8 0.9209 0.0621 1.922860 20.88
9 1.6374 D9 (variable)
10 ∞ 0.0545 (Aperture S)
11 * 0.6296 0.1084 1.697200 53.29
12 * -7.0731 0.0036
13 0.8007 0.1091 1.496997 81.61
14 -1.3105 0.0364 1.903658 31.31
15 1.3795 0.1091
16 3.6363 0.0727 1.593190 67.90
17 * -0.7884 D17 (variable)
18 * -0.7782 0.0545 1.589130 61.22
19 * 1.0909 D19 (variable)
20 1.2692 0.1455 1.618000 63.34
21 3.6363 D21 (variable)
22 ∞ 0.0255 1.516800 63.88
23 ∞ 0.0545
24 ∞ 0.0255 1.516800 63.88
25 ∞ 0.0182
Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10
6 1.0 2.4187E-01 -2.2760E + 00 2.5912E + 01 -1.0907E + 02
7 1.0 6.3257E-01 -6.1931E-01 7.8691E + 00 0.0000E + 00
11 1.0 5.9853E-01 1.7723E + 00 5.9018E + 00 3.7762E + 01
12 1.0 9.9096E-01 -1.4495E + 00 0.0000E + 00 0.0000E + 00
17 1.0 2.3005E + 00 6.4907E + 00 0.0000E + 00 0.0000E + 00
18 1.0 1.2244E + 01 -2.2325E + 02 2.7489E + 03 -1.7961E + 04
19 1.0 1.1244E + 01 -1.9861E + 02 2.2433E + 03 -1.2878E + 04

[Overall specifications]
Zoom ratio 2.822
Wide angle end Intermediate focus Telephoto end f 1.00000 1.63634 2.82177
FNo 3.57913 4.48247 5.80288
ω 29.01821 17.78749 10.59168
Y 0.524 0.524 0.524
Bf 0.53300 1.03947 1.18408
TL 3.155 3.428 4.402

[Zooming data]
Variable interval Wide-angle end Intermediate focus Telephoto end
D3 0.03010 0.25772 0.62245
D9 0.67781 0.30314 0.09948
D17 0.11854 0.09576 0.07388
D19 0.55912 0.49568 1.18643
D21 0.42708 0.93318 1.07780

[Zoom lens group data]
Group number Group first surface Group focal length Lens construction length G1 1 2.85950 0.1344
G2 4 -0.79533 0.4075
G3 11 0.63101 0.4939
G4 18 -0.76271 0.0545
G5 20 3.08268 0.1455

[Conditional expression]
Conditional expression (1) D1 / fw = 0.134
Conditional expression (2) (TL5-WL5) /ft=0.231

  From Table 3, it can be seen that the zoom lens ZL3 according to the present example satisfies the conditional expressions (1) and (2).

  FIG. 6 is a diagram illustrating various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma diagram, and chromatic aberration diagram of magnification) of the zoom lens according to the third example. FIG. 6A is a diagram of various aberrations at the shooting distance at infinity in the wide-angle end state of this embodiment, and FIG. 6B is a diagram of various aberrations at the shooting distance infinite in the intermediate focal length state of this embodiment. FIG. 6C is a diagram of various aberrations at the shooting distance infinite in the telephoto end state.

  As is apparent from the respective aberration diagrams shown in FIG. 6, it can be seen that the zoom lens ZL3 according to Example 3 has excellent optical performance with various aberrations corrected well.

  In order to make the present invention easy to understand, the configuration requirements of the embodiment have been described, but it goes without saying that the present invention is not limited to this.

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

  In addition, a single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to be a focusing lens group that performs focusing from an object at infinity to a near object. 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, the fourth lens group G4 is preferably a focusing lens group. Further, the fifth lens group G5 may be a focusing lens group. Alternatively, focusing can be performed by simultaneously moving the fourth lens group G4 and the fifth lens group G5.

  In addition, the lens group or the partial lens group is moved so as to have a component in a direction perpendicular to the optical axis, or is rotated (swayed) in the in-plane direction including the optical axis to reduce image blur caused by camera shake. A vibration-proof lens group to be corrected may be used. In particular, the second lens group G2 or the third lens group G3 is preferably an anti-vibration lens group.

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

  The aperture stop S is preferably arranged in the vicinity of the third lens group G3. However, the role of the aperture stop may be substituted by a lens frame without providing a member as an aperture stop.

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

ZL (ZL1 to ZL3) Zoom lens G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group G5 Fifth lens group S Aperture stop FL filter group I Image surface CAM Digital still camera (optical equipment)

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, and a negative The fourth lens group having refractive power and the fifth lens group having positive refractive power substantially consist of five lens groups, and all the lens groups move on the optical axis at the time of zooming, and each lens The group spacing changes,
The first lens group is composed of two lenses,
The second lens group is composed of a negative lens, a negative lens, and a positive lens arranged in order from the object side.
The third lens group is composed of a positive lens, a cemented lens of a positive lens and a negative lens, and a positive lens arranged in order from the object side.
The fourth lens group is composed of one negative lens,
The fifth lens group is composed of one positive lens,
The distance on the optical axis from the most object side surface to the image plane of the fifth lens group is larger in the telephoto end state than in the wide-angle end state,
An aperture stop is disposed between the second lens group and the third lens group;
The aperture stop moves on the optical axis together with the third lens group at the time of zooming,
A zoom lens satisfying the following conditional expression:
0.07 <D1 / fw ≦ 0.134
Or
0.454 ≦ D1 / fw <0.46
However,
D1: thickness of the first lens group on the optical axis;
fw: focal length of the zoom lens in the wide-angle end state. 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, and a negative The fourth lens group having refractive power and the fifth lens group having positive refractive power substantially consist of five lens groups, and all the lens groups move on the optical axis at the time of zooming, and each lens The group spacing changes,
The first lens group is composed of a cemented lens composed of a negative lens and a positive lens arranged in order from the object side,
The third lens group is composed of a positive lens, a cemented lens of a positive lens and a negative lens, and a positive lens arranged in order from the object side.
An aperture stop is disposed between the second lens group and the third lens group;
The aperture stop moves on the optical axis together with the third lens group at the time of zooming,
A zoom lens satisfying the following conditional expression:
0.07 <D1 / fw <0.46
0.23 <(TL5-WL5) /ft≦0.323
However,
D1: thickness of the first lens group on the optical axis;
fw: focal length of the zoom lens in the wide-angle end state;
WL5: distance on the optical axis from the most object side surface to the image plane of the fifth lens group in the wide-angle end state;
TL5: distance on the optical axis from the most object side surface to the image plane of the fifth lens group in the telephoto end state;
ft: focal length of the zoom lens in the telephoto end state. 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, and a negative The fourth lens group having refractive power and the fifth lens group having positive refractive power substantially consist of five lens groups, and all the lens groups move on the optical axis at the time of zooming, and each lens The group spacing changes,
The first lens group is composed of two lenses,
The third lens group is composed of a positive lens, a cemented lens of a positive lens and a negative lens, and a positive lens arranged in order from the object side.
The fifth lens group is composed of one positive lens,
An aperture stop is disposed between the second lens group and the third lens group;
The aperture stop moves on the optical axis together with the third lens group at the time of zooming,
A zoom lens satisfying the following conditional expression:
0.07 <D1 / fw <0.46
0.23 <(TL5-WL5) /ft≦0.323
However,
D1: thickness of the first lens group on the optical axis;
fw: focal length of the zoom lens in the wide-angle end state;
WL5: distance on the optical axis from the most object side surface to the image plane of the fifth lens group in the wide-angle end state;
TL5: distance on the optical axis from the most object side surface to the image plane of the fifth lens group in the telephoto end state;
ft: focal length of the zoom lens in the telephoto end state.   4. The zoom lens according to claim 2, wherein a distance on the optical axis from the most object side surface to the image plane of the fifth lens group is larger in the telephoto end state than in the wide-angle end state. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.23 <(TL5-WL5) / ft <1.20
However,
WL5: distance on the optical axis from the most object side surface to the image plane of the fifth lens group in the wide-angle end state;
TL5: distance on the optical axis from the most object side surface to the image plane of the fifth lens group in the telephoto end state;
ft: focal length of the zoom lens in the telephoto end state.   The zoom lens according to claim 1, wherein the first lens group includes a negative lens and a positive lens arranged in order from the object side.   The zoom lens according to claim 1, wherein the first lens group includes a cemented lens including the two lenses.   4. The zoom lens according to claim 2, wherein the second lens group includes a negative lens, a negative lens, and a positive lens arranged in order from the object side.   The zoom lens according to claim 2, wherein the fifth lens group includes a single positive lens.   An optical apparatus comprising the zoom lens according to any one of claims 1 to 9.

Images