JP2015026032A - Variable power optical system, optical device, and method for manufacturing variable power optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable power optical system which achieves quick and silent AF without enlarging a lens barrel by reducing the size and weight of a lens group for focusing, and in which the variation in aberrations when varying power from a wide angle end state to a telephoto end state and when focusing from an infinite object to a short distance object is excellently suppressed, and to provide an optical device and a method for manufacturing the variable power optical system.SOLUTION: A variable power optical system ZL to be used in an optical device such as a camera 1, includes, in order from the object side: a first lens group G1 having a positive refractive power; a second lens group G2 having a negative refractive power; a third lens group G3 having a positive refractive power; a fourth lens group G4 having a positive refractive power; and a rear lens group GR including at least one lens group. When varying power from a wide angle end state to a telephoto end state, the distances between the lens groups are changed. When focusing from infinity to a short distance object, the third lens group G3 moves along the optical axis.

Description

  The present invention relates to a variable magnification optical system, an optical apparatus, and a method for manufacturing the variable magnification optical system.

  Conventionally, a variable power optical system suitable for a photographic camera, an electronic still camera, a video camera, etc. in which a focusing lens group has been reduced in weight by introducing an IF (inner focus) system has been proposed (for example, a patent) Reference 1).

Japanese Patent No. 4876509

  However, in a conventional variable magnification optical system, the weight of the focusing lens group is insufficient to achieve sufficient silence during AF (auto focus), and the weight of the focusing lens group Therefore, when performing AF at a high speed, a large motor and actuator are required, and there is a problem that the lens barrel becomes large.

  The present invention has been made in view of such a problem. By reducing the size and weight of the focusing lens group, high-speed AF without increasing the size of the lens barrel and quietness during AF are realized. Further, a variable power optical system, an optical apparatus, and the variable power system that satisfactorily suppress aberration fluctuations during zooming from the wide-angle end state to the telephoto end state and aberration fluctuations during focusing from an object at infinity to a short distance object. It is an object of the present invention to provide a method for manufacturing a double optical system.

In order to solve the above problems, a variable magnification optical system according to the present invention includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refraction. A third lens group having a power, a fourth lens group having a positive refractive power, and a subsequent lens group including at least one lens group, and upon zooming from the wide-angle end state to the telephoto end state, The distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, the distance between the third lens group and the fourth lens group changes, and the fourth When the distance between the lens group and the subsequent lens group changes and the subsequent lens group is composed of a plurality of lens groups, the distance between each of the plurality of lens groups changes, and when focusing from infinity to a close object, The third lens group moves along the optical axis and satisfies the following condition:
0.60 <f3 / f4 <1.30
However,
f3: focal length of the third lens group f4: focal length of the fourth lens group

  In such a variable magnification optical system, it is preferable that the first lens unit moves in the object direction when changing magnification from the wide-angle end state to the telephoto end state.

  Also, in such a variable magnification optical system, the distance between the first lens group and the second lens group is increased during the magnification change from the wide-angle end state to the telephoto end state, and the second lens group and the third lens group Preferably, the distance between the third lens group and the fourth lens group is increased, and the distance between the fourth lens group and the fifth lens group is increased.

  In such a variable magnification optical system, it is preferable that the third lens group is composed of only one positive lens or one cemented lens having a positive refractive power.

  In such a variable magnification optical system, it is preferable that the most object side surface of the third lens group is an aspherical surface.

  In such a variable magnification optical system, it is preferable that the aspherical surface has a shape in which the positive refractive power decreases as the distance from the optical axis increases.

Moreover, it is preferable that such a variable magnification optical system satisfies the condition of the following formula.
0.11 <(− f2) / f1 <0.19
However,
f2: Focal length of the second lens group f1: Focal length of the first lens group

Moreover, it is preferable that such a variable magnification optical system satisfies the condition of the following formula.
3.00 <f1 / fw <6.00
However,
f1: Focal length of the first lens unit fw: Focal length of the entire system in the wide-angle end state

  Further, in such a variable magnification optical system, it is preferable to move at least a part of the subsequent lens group so as to have a component in a direction orthogonal to the optical axis.

  An optical apparatus according to the present invention includes any one of the above-described variable magnification optical systems.

The variable magnification optical system manufacturing method according to the present invention has, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. A method of manufacturing a variable magnification optical system having a third lens group, a fourth lens group having a positive refractive power, and a subsequent lens group including at least one lens group, from a wide-angle end state to a telephoto end state During zooming, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, and the distance between the third lens group and the fourth lens group. Is changed, when the interval between the fourth lens group and the subsequent lens group is changed, and when the subsequent lens group is composed of a plurality of lens groups, it is arranged so that the interval between each of the plurality of lens groups is changed, The third lens group moves along the optical axis when focusing from infinity to a close object Arranged, characterized in that arranged so as to satisfy the condition of following equation.
0.60 <f3 / f4 <1.30
However,
f3: focal length of the third lens group f4: focal length of the fourth lens group

  According to the present invention, by reducing the size and weight of the focusing lens group, high-speed AF without increasing the size of the lens barrel and quietness at the time of AF are realized, and further, from the wide-angle end state to the telephoto end state A variable magnification optical system, an optical apparatus, and a method of manufacturing the variable magnification optical system, which can satisfactorily suppress aberration fluctuation during zooming and aberration fluctuation during focusing from an object at infinity to a short distance object Can do.

It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 1st Example. FIG. 4 is a diagram illustrating various aberrations of the variable magnification optical system according to the first example when focusing on infinity, where (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows telephoto. Indicates the end state. FIG. 4 is a diagram illustrating various aberrations of the zoom optical system according to the first example when focusing at short distance, where (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows telephoto. Indicates the end state. It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 2nd Example. FIG. 6 is a diagram illustrating various aberrations of the variable magnification optical system according to Example 2 when focusing at infinity, where (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows telephoto. Indicates the end state. FIG. 6 is a diagram illustrating various aberrations when the zooming optical system according to Example 2 is in focus at short distance, where (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows telephoto. Indicates the end state. It is sectional drawing of the camera carrying the said variable magnification optical system. It is a flowchart for demonstrating the manufacturing method of the said variable magnification optical system.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the variable magnification optical system ZL according to the present embodiment includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, A third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and a subsequent lens group GR including at least one lens group are configured. In addition, in the zoom optical system ZL, when the zoom is changed from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group G2 changes, and the second lens group G2 and the third lens are changed. The distance between the group G3 changes, the distance between the third lens group G3 and the fourth lens group G4 changes, the distance between the fourth lens group G4 and the subsequent lens group GR changes, and further, the subsequent lens group GR. Is composed of a plurality of lens groups, it is possible to achieve good aberration correction at the time of zooming by changing the interval between the plurality of lens groups.

  In the variable magnification optical system ZL, the distance between the first lens group G1 and the second lens group G2 increases during the magnification change from the wide-angle end state to the telephoto end state, and the second lens group G2 and the third lens group G3. , The distance between the third lens group G3 and the fourth lens group G4 is increased, and the distance between the fourth lens group G4 and the fifth lens group G5 is increased. Can be secured. Furthermore, the zoom optical system ZL is configured to move the first lens group G1 in the object direction when zooming from the wide-angle end state to the telephoto end state, thereby reducing the total lens length in the wide-angle end state. The effective diameter of the first lens group can be reduced, and the variable magnification optical system ZL can be reduced in size.

  The variable magnification optical system ZL is configured such that the third lens group G3 moves along the optical axis when focusing from an object at infinity to an object at a short distance. By adopting such a configuration, it is possible to suppress a change in the image size during focusing, and it is possible to satisfactorily suppress aberration fluctuations such as spherical aberration. In the following description, the third lens group G3 is also referred to as a “focus lens group”.

  In addition, it is desirable that the variable magnification optical system ZL satisfies the following conditional expression (1).

0.60 <f3 / f4 <1.30 (1)
However,
f3: Focal length of the third lens group G3 f4: Focal length of the fourth lens group G4

  Conditional expression (1) indicates that the focal point of the third lens group G3 with respect to the focal length of the fourth lens group G4, which is suitable for suppressing aberration fluctuations during focusing from an object at infinity to an object at a short distance and correcting various aberrations favorably. It defines the distance. If the upper limit of conditional expression (1) is exceeded, the refractive power of the fourth lens group G4 will increase, and it will be difficult to correct various aberrations including spherical aberration. In addition, the refractive power of the third lens group G3 decreases, and the amount of movement of the third lens group G3 during focusing from an object at infinity to an object at a short distance increases, leading to an increase in the total lens length. In addition, the effect of this application can be made more reliable by setting the upper limit of conditional expression (1) to 1.10. On the other hand, if the lower limit of conditional expression (1) is not reached, the refractive power of the third lens group G3 becomes large, and the aberration fluctuation at the time of focusing from an object at infinity to an object at short distance becomes large. In addition, the effect of this application can be made more reliable by setting the lower limit of conditional expression (1) to 0.80.

  In the zoom optical system ZL, it is desirable that the third lens group G3, which is a focusing lens group, is composed of only one positive lens or one cemented lens having a positive refractive power. With this configuration, the focusing lens group is reduced in weight, and high-speed AF and quietness during AF can be achieved without increasing the size of the lens barrel.

  In the variable magnification optical system ZL, it is desirable that the most object side surface of the third lens group G3 which is a focusing lens group is an aspherical surface. At this time, it is more desirable that the aspherical shape be a shape that weakens the positive refractive power as the distance from the optical axis increases. With this configuration, it is possible to achieve both weight reduction of the focusing lens group and suppression of aberration fluctuations when focusing from an object at infinity to a close object, high-speed AF without increasing the size of the lens barrel, and AF Silence can be realized.

  In addition, it is desirable that the variable magnification optical system ZL satisfies the following conditional expression (2).

0.11 <(− f2) / f1 <0.19 (2)
However,
f2: Focal length of the second lens group G2 f1: Focal length of the first lens group G1

  Conditional expression (2) defines the focal length of the second lens group G2 with respect to the focal length of the first lens group G1 in order to ensure a sufficient zoom ratio and realize good optical performance. If the upper limit value of conditional expression (2) is exceeded, the refractive power of the first lens group G1 becomes strong, and the spherical aberration at the telephoto end is significantly deteriorated. Further, the deterioration of lateral chromatic aberration at the wide-angle end becomes remarkable, which is not preferable. In addition, the effect of this application can be made more reliable by making the upper limit of conditional expression (2) 0.16. On the other hand, if the lower limit of conditional expression (2) is not reached, the refractive power of the second lens group G2 becomes strong, and it becomes difficult to correct off-axis aberrations, particularly field curvature and astigmatism, at the wide-angle end. In addition, the effect of this application can be made more reliable by setting the lower limit of conditional expression (2) to 0.14.

  In addition, it is desirable that the variable magnification optical system ZL satisfies the following conditional expression (3).

3.00 <f1 / fw <6.00 (3)
However,
f1: Focal length of the first lens group G1 fw: Focal length of the entire system in the wide-angle end state

  Conditional expression (3) defines an appropriate focal length of the first lens group G1 with respect to the focal length of the variable magnification optical system ZL in the wide-angle end state. By satisfying this conditional expression (3), it is possible to achieve both a reduction in the overall lens length and good correction of curvature of field, distortion, and spherical aberration. If the lower limit of conditional expression (3) is not reached, the refractive power of the first lens group G1 will increase, making it difficult to correct various aberrations including spherical aberration. In addition, the effect of this application can be made more reliable by setting the lower limit of conditional expression (3) to 4.00. On the other hand, if the upper limit value of the conditional expression (3) is exceeded, the refractive power of the first lens group G1 becomes small, and it becomes difficult to reduce the total lens length. In addition, the effect of this application can be made more reliable by setting the upper limit of conditional expression (3) to 5.00.

  The variable magnification optical system ZL is a lens group that corrects displacement of the imaging position due to camera shake or the like by moving at least a part of the subsequent lens group GR so as to have a component in a direction orthogonal to the optical axis. It is desirable to have With this configuration, it is possible to effectively correct the displacement of the imaging position due to camera shake or the like.

  Next, a camera that is an optical device including the variable magnification optical system ZL according to the present embodiment will be described with reference to FIG. This camera 1 is a so-called mirrorless camera of interchangeable lens provided with a variable magnification optical system ZL according to the present embodiment as a photographing lens 2. In the camera 1, light from an object (subject) (not shown) is collected by the photographing lens 2 and is on the imaging surface of the imaging unit 3 via an OLPF (Optical low pass filter) (not shown). A subject image is formed on the screen. Then, the subject image is photoelectrically converted by the photoelectric conversion element provided in the imaging unit 3 to generate an image of the subject. This image is displayed on an EVF (Electronic view finder) 4 provided in the camera 1. Thus, the photographer can observe the subject via the EVF 4.

  Further, when a release button (not shown) is pressed by the photographer, an image photoelectrically converted by the imaging unit 3 is stored in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1. In the present embodiment, an example of a mirrorless camera has been described. However, a variable power optical system ZL according to the present embodiment is applied to a single-lens reflex camera that has a quick return mirror in the camera body and observes a subject with a finder optical system. Even when the camera is mounted, the same effect as the camera 1 can be obtained.

  As described above, the optical apparatus according to the present embodiment includes the variable magnification optical system ZL having the above-described configuration, thereby realizing high-speed AF without increasing the size of the lens barrel and quietness during AF, Furthermore, it is possible to realize an optical apparatus that can satisfactorily suppress aberration fluctuations during zooming from the wide-angle end state to the telephoto end state and during focusing from an object at infinity to a short-distance object.

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

  In the present embodiment, the variable magnification optical system ZL having a configuration of five groups or more is shown, but the above-described configuration conditions and the like can be applied to other group configurations such as the sixth group and the seventh group. 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.

  Alternatively, 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. In this case, the focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (such as an ultrasonic motor). In particular, it is preferable that the third lens group G3 is a focusing lens group as described above.

  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, as described above, it is preferable that at least a part of the subsequent lens group GR is an anti-vibration lens group.

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

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

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

  The variable magnification optical system ZL of the present embodiment has a variable magnification ratio of about 5 to 15 times.

  Hereinafter, an outline of a method for manufacturing the variable magnification optical system ZL according to the present embodiment will be described with reference to FIG. First, each lens is arranged to prepare the first to fourth lens groups G1 to G4 and the subsequent lens group GR, respectively (step S100). Further, upon zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group G2 changes, and the distance between the second lens group G2 and the third lens group G3 changes. The distance between the third lens group G3 and the fourth lens group G4 is changed, and the distance between the fourth lens group G4 and the subsequent lens group GR is changed (Step S200). Further, the third lens group G3 is arranged so as to move along the optical axis when focusing from infinity to a close object (step S300). Furthermore, the lens groups G1 to G4 and GR are arranged so as to satisfy the conditional expression (1) (step S400).

  Specifically, in the present embodiment, for example, as illustrated in FIG. 1, a cemented positive lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12 in order from the object side; A positive meniscus lens L13 having a convex surface facing the object side is arranged as the first lens group G1, and an aspheric surface made of plastic resin is provided on the object side surface of the negative meniscus lens having a convex surface facing the object side. A negative lens L21, a biconcave negative lens L22, a biconvex positive lens L23, and a biconcave negative lens L24 are arranged to form the second lens group G2, and the object side lens surface is aspherical. A cemented lens of a positive lens L31 and a negative meniscus lens L32 having a concave surface facing the object side is arranged to form a third lens group G3, and a negative meniscus lens L41 having a convex surface facing the object side and a biconvex positive lens. The fourth lens unit G4 is formed by arranging a cemented positive lens with L42, and includes a cemented negative lens of a negative lens L51 having an aspheric object side lens surface and a positive meniscus lens L52 having a convex surface facing the object side. The fifth lens group G5, and a sixth lens group including a biconvex positive lens L61 and a cemented positive lens of a biconvex positive lens L62 and a negative meniscus lens L63 having a concave surface facing the object side are arranged. Thus, the subsequent lens group GR is obtained. The lens groups thus prepared are arranged in the above-described procedure to manufacture the variable magnification optical system ZL.

  Hereinafter, each example of the present application will be described with reference to the drawings. 1 and 4 are cross-sectional views showing the configuration and refractive power distribution of the variable magnification optical system ZL (ZL1, ZL2) according to each example. Further, in the lower part of the sectional views of these variable magnification optical systems ZL1 and ZL2, each lens group G1 to G4, GR (G5, G6) when changing magnification from the wide-angle end state (W) to the telephoto end state (T) is shown. The direction of movement along the optical axis is indicated by arrows.

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

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)

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

[First embodiment]
FIG. 1 is a diagram showing a configuration of a variable magnification optical system ZL1 according to the first example. The zoom optical system ZL1 shown in FIG. 1 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, an aperture stop S, and a positive The lens unit includes a third lens group G3 having a refractive power, a fourth lens group G4 having a positive refractive power, and a subsequent lens group GR. The subsequent lens group GR includes, in order from the object side, a fifth lens group G5 having a negative refractive power and a sixth lens group G6 having a positive refractive power.

  In the variable magnification optical system ZL1, the first lens group G1 includes, in order from the object side, a cemented positive lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, and an object side. It is composed of a positive meniscus lens L13 having a convex surface. The second lens group G2 includes, in order from the object side, a negative lens L21 provided with an aspheric surface made of plastic resin on the object side surface of a negative meniscus lens having a convex surface facing the object side, and a biconcave shape. The lens includes a negative lens L22, a biconvex positive lens L23, and a biconcave negative lens L24. The third lens group G3 includes, in order from the object side, a cemented lens of a positive lens L31 having an aspheric object side lens surface and a negative meniscus lens L32 having a concave surface facing the object side. The fourth lens group G4 includes, in order from the object side, a cemented positive lens composed of a negative meniscus lens L41 having a convex surface directed toward the object side and a biconvex positive lens L42. The fifth lens group G5 includes, in order from the object side, a cemented negative lens of a negative lens L51 having an aspheric object side lens surface and a positive meniscus lens L52 having a convex surface facing the object side. The sixth lens group G6 includes, in order from the object side, a biconvex positive lens L61, and a cemented positive lens of a biconvex positive lens L62 and a negative meniscus lens L63 with a concave surface facing the object side. Has been.

  In the zoom optical system ZL1 according to the first example, the air gap between the first lens group G1 and the second lens group G2 increases when zooming from the wide-angle end state to the telephoto end state, and the second lens group. The air gap between G2 and the third lens group G3 decreases, the air gap between the third lens group G3 and the fourth lens group G4 increases, and the air gap between the fourth lens group G4 and the fifth lens group G5 increases. Each lens group from the first lens group G1 to the sixth lens group G6 moves in the object direction so that the air gap between the fifth lens group G5 and the sixth lens group G6 decreases and increases. At this time, the aperture stop S moves together with the fourth lens group G4 (with the same movement amount).

  In addition, the variable magnification optical system ZL1 according to the first example moves the third lens group G3 that is a focusing lens group from the long-distance object to the short-distance object by moving the third lens group G3 along the optical axis in the image plane direction. Is focused.

The variable magnification optical system ZL1 according to the first example corrects the displacement of the imaging position due to camera shake or the like by moving the fifth lens group G5 so as to have a component in a direction orthogonal to the optical axis. To do.

  Table 1 below lists values of specifications of the variable magnification optical system ZL1 according to the first example. In Table 1, f in the overall specifications represents the focal length of the entire system, FNO represents the F number, 2ω represents the angle of view, Ymax represents the maximum image height, and TL represents the total length. Here, the total length TL represents the distance on the optical axis from the first surface of the lens surface to the image plane I when focusing on infinity. In the lens data, the first column m indicates the order (surface number) of the lens surfaces from the object side along the traveling direction of the light beam, the second column r indicates the curvature radius of each lens surface, and the third column. d is the distance on the optical axis from each optical surface to the next optical surface (surface interval). The fourth column nd and the fifth column νd are the refractive index and Abbe number for the d-line (λ = 587.6 nm). Is shown. Further, the radius of curvature ∞ indicates a plane, and the refractive index of air 1.000 is omitted. The surface numbers 1 to 29 shown in Table 1 correspond to the numbers 1 to 29 shown in FIG. The lens group focal length indicates the start surface and focal length of each of the first to sixth lens groups G1 to G6.

  Here, the focal length f, the radius of curvature r, the surface interval d, and other length units listed in all the following specification values are generally “mm”, but the optical system is proportionally enlarged or proportional. Since the same optical performance can be obtained even if the image is reduced, the present invention is not limited to this. The description of these symbols and the description of the specification table are the same in the following embodiments.

(Table 1) First Example [Overall Specifications]
Scaling ratio = 7.44
Wide-angle end state Intermediate focal length state Telephoto end state f = 18.5 to 69.5 to 137.5
FNO = 3.37 to 5.07 to 5.87
2ω = 78.10-22.38-11.42
Ymax = 14.25 to 14.25 to 14.25
TL = 149.23-191.09-211.23

[Lens data]
m r d nd νd
Object ∞
1 198.0585 2.000 1.84666 23.78
2 71.0593 8.436 1.59319 67.90
3 -281.2745 0.100
4 64.3516 4.808 1.81600 46.62
5 209.7899 d5
6 * 91.7725 0.150 1.55389 38.23
7 87.5466 1.200 1.77250 49.61
8 13.5061 5.769
9 -35.0552 1.000 1.81600 46.62
10 42.8672 0.839
11 31.6462 5.245 1.84666 23.78
12 -26.4739 0.392
13 -23.1802 1.000 1.88300 40.76
14 937.7494 d14
15 ∞ d15 Aperture stop S
16 * 28.1133 5.000 1.48749 70.40
17 -30.8336 1.000 1.84666 23.78
18 -46.1545 d18
19 34.2511 1.000 2.00069 25.45
20 23.7294 5.400 1.49782 82.51
21 -34.5514 d21
22 * -77.1085 1.400 1.77250 49.61
23 17.7029 2.768 1.84666 23.78
24 31.2636 d24
25 182.8242 3.970 1.57221 46.67
26 -34.4813 0.100
27 37.3517 6.951 1.48749 70.40
28 -21.1812 1.300 1.90265 35.70
29 -119.3320 BF
Image plane ∞

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 85.560
Second lens group 6 -13.001
Third lens group 16 42.405
Fourth lens group 19 45.251
5th lens group 22 -30.006
6th lens group 25 44.754

  In the zoom optical system ZL1 according to the first example, the sixth surface, the sixteenth surface, and the twenty-second surface are formed in an aspherical shape. The following Table 2 shows aspheric data, that is, the values of the conic constant K and the aspheric constants A4 to A10.

(Table 2)
[Aspherical data]
K A4 A6 A8 A10
6th surface 11.2598 6.09566E-06 -4.17845E-08 1.53230E-10 -3.43299E-13
16th surface -0.5485 -1.67764E-05 1.74753E-08 -1.42820E-10 0.00000E + 00
22nd surface 0.6725 8.48847E-06 -1.22182E-08 1.81567E-10 0.00000E + 00

  In the variable magnification optical system ZL1 according to the first example, the axial air distance d5 between the first lens group G1 and the second lens group G2, the axial air distance d14 between the second lens group G2 and the aperture stop S, The axial air gap d15 between the aperture stop S and the third lens group G3, the axial air gap d18 between the third lens group G3 and the fourth lens group G4, and the axes of the fourth lens group G4 and the fifth lens group G5 The upper air interval d21, the on-axis air interval d24 between the fifth lens group G5 and the sixth lens group G6, and the back focus BF change as described above. Table 3 below shows the values of the variable interval and the back focus at the respective focal lengths in the wide-angle end state, the intermediate focal length state, and the telephoto end state when focusing on infinity and focusing on a short distance. Note that the back focus BF indicates the distance on the optical axis from the most image side lens surface (the 29th surface in FIG. 1) to the image surface I. This description is the same in the following embodiments.

(Table 3)
[Variable interval data]
Infinity focusing state Short-distance focusing state Wide-angle end Intermediate Telephoto end Wide-angle end Intermediate Telephoto end f 18.5 69.5 137.5 18.5 69.5 137.5
d5 1.500 28.095 44.228 1.500 28.095 44.228
d14 21.923 5.441 3.000 21.923 5.441 3.000
d15 6.423 4.512 2.000 6.862 4.833 2.504
d18 3.063 4.974 7.486 2.624 4.653 6.982
d21 2.500 6.346 7.564 2.500 6.346 7.564
d24 10.064 6.218 5.000 10.064 6.218 5.000
BF 38.02 69.76 76.21 38.02 69.76 76.21

  Table 4 below shows values corresponding to the conditional expressions in the variable magnification optical system ZL1 according to the first example. In Table 4, f1 is the focal length of the first lens group G1, f2 is the focal length of the second lens group G2, f3 is the focal length of the third lens group G3, and f4 is the fourth lens group G4. Fw represents the focal length of the entire variable magnification optical system ZL1. The description of the above symbols is the same in the following embodiments.

(Table 4)
[Conditional value]
(1) f3 / f4 = 0.937
(2) (−f2) /f1=0.152
(3) f1 / fw = 4.627

  Thus, the variable magnification optical system ZL1 according to the first example satisfies all the conditional expressions (1) to (3).

  FIG. 2 shows various aberration diagrams of the variable magnification optical system ZL1 according to the first example when focusing at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, and shows the wide-angle end state and the intermediate focal length state. FIG. 3 is a diagram showing various aberrations when focusing at a short distance in the telephoto end state. In each aberration diagram, FNO represents an F number, NA represents a numerical aperture, and Y represents an image height. The spherical aberration diagram shows the F-number or numerical aperture value corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum image height, and the coma diagram shows the value of each image height. . d represents a d-line (λ = 587.6 nm), and g represents a g-line (λ = 435.8 nm). In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. Also, in the aberration diagrams of the respective examples shown below, the same reference numerals as those of the present example are used. From these respective aberration diagrams, the variable magnification optical system ZL1 according to the first example has excellent imaging performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state. It can be seen that the imaging performance is excellent even during focusing.

[Second Embodiment]
FIG. 4 is a diagram showing a configuration of the variable magnification optical system ZL2 according to the second example. The zoom optical system ZL2 shown in FIG. 4 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, an aperture stop S, and a positive The lens unit includes a third lens group G3 having a refractive power, a fourth lens group G4 having a positive refractive power, and a subsequent lens group GR. The subsequent lens group GR includes, in order from the object side, a fifth lens group G5 having a negative refractive power and a sixth lens group G6 having a positive refractive power.

  In the variable magnification optical system ZL2, the first lens group G1 includes, in order from the object side, a cemented positive lens of a negative meniscus lens L11 having a convex surface directed toward the object side and a biconvex positive lens L12, and an object side. It is composed of a positive meniscus lens L13 having a convex surface. The second lens group G2 includes, in order from the object side, a negative lens L21 provided with an aspheric surface made of plastic resin on the object side surface of a negative meniscus lens having a convex surface facing the object side, and a biconcave shape. The lens includes a negative lens L22, a biconvex positive lens L23, and a biconcave negative lens L24. The third lens group G3 includes a positive lens L31 having an aspheric object side lens surface. The fourth lens group G4 includes, in order from the object side, a cemented positive lens composed of a negative meniscus lens L41 having a convex surface facing the object side and a biconvex positive lens L42. The fifth lens group G5 includes, in order from the object side, a cemented negative lens of a negative lens L51 having an aspheric object side lens surface and a positive meniscus lens L52 having a convex surface facing the object side. The sixth lens group G6 includes, in order from the object side, a biconvex positive lens L61, and a cemented positive lens of a biconvex positive lens L62 and a negative meniscus lens L63 having a concave surface facing the object side. Has been.

  In the zoom optical system ZL2 according to the second example, the air gap between the first lens group G1 and the second lens group G2 increases during zooming from the wide-angle end state to the telephoto end state, and the second lens group. The air gap between G2 and the third lens group G3 decreases, the air gap between the third lens group G3 and the fourth lens group G4 increases, and the air gap between the fourth lens group G4 and the fifth lens group G5 increases. Each lens group from the first lens group G1 to the sixth lens group G6 moves in the object direction so that the air gap between the fifth lens group G5 and the sixth lens group G6 decreases and increases. At this time, the aperture stop S moves together with the fourth lens group G4 (with the same movement amount).

  Further, the variable magnification optical system ZL2 according to the second example moves the third lens group G3 that is a focusing lens group from the long-distance object to the short-distance object by moving in the image plane direction along the optical axis. Is focused.

The variable magnification optical system ZL2 according to the second example corrects the displacement of the imaging position due to camera shake or the like by moving the fifth lens group G5 so as to have a component in a direction orthogonal to the optical axis. To do.

  Table 5 below lists values of specifications of the variable magnification optical system ZL2 according to the second example. The surface numbers 1 to 28 shown in Table 5 correspond to the numbers 1 to 28 shown in FIG.

(Table 5) Second Example [Overall Specifications]
Scaling ratio = 7.41
Wide-angle end state Intermediate focal length state Telephoto end state f = 18.5 to 70.1 to 137.2
FNO = 3.45 to 5.13 to 5.89
2ω = 78.06-22.18-11.50
Ymax = 14.25 to 14.25 to 14.25
TL = 150.24 to 192.79 to 211.18

[Lens data]
m r d nd νd
Object ∞
1 164.7224 2.000 1.84666 23.78
2 69.2610 9.569 1.49782 82.51
3 -215.6328 0.100
4 59.9128 5.133 1.77250 49.61
5 210.3577 d5
6 * 151.4197 0.150 1.55389 38.23
7 141.4818 1.200 1.77250 49.61
8 13.4456 5.852
9 -46.9540 1.000 1.81600 46.62
10 50.1225 0.500
11 27.2349 5.330 1.84666 23.78
12 -29.7129 0.313
13 -26.7614 1.000 1.88300 40.76
14 69.1420 d14
15 ∞ d15 Aperture stop S
16 * 28.2763 4.500 1.49782 82.51
17 -63.7625 d17
18 41.6479 1.000 1.84666 23.78
19 25.3852 6.300 1.48749 70.40
20 -26.7000 d20
21 * -67.5835 1.400 1.77250 49.61
22 18.4411 2.600 1.85026 32.35
23 30.5414 d23
24 126.3398 3.816 1.54282 48.67
25 -47.7988 0.100
26 42.8945 7.746 1.48749 70.40
27 -20.5949 1.300 1.90265 35.70
28 -57.7623 BF
Image plane ∞

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 85.126
Second lens group 6 -12.427
Third lens group 16 40.000
4th lens group 18 41.836
5th lens group 21 -28.132
6th lens group 24 43.839

  In the variable magnification optical system ZL2 according to the second example, the sixth surface, the sixteenth surface, and the twenty-first surface are formed in an aspherical shape. Table 6 below shows the aspheric data, that is, the values of the conic constant K and the aspheric constants A4 to A10.

(Table 6)
[Aspherical data]
K A4 A6 A8 A10
6th surface 3.5648 8.42661E-06 -5.67193E-08 2.35593E-10 -4.71958E-13
16th surface -0.6804 -2.20261E-05 1.26254E-08 -2.16161E-10 0.00000E + 00
Side 21 1.4368 7.94766E-06 4.75605E-09 1.24853E-10 0.00000E + 00

  In the variable magnification optical system ZL2 according to the second example, the axial air distance d5 between the first lens group G1 and the second lens group G2, the axial air distance d14 between the second lens group G2 and the aperture stop S, The axial air gap d15 between the aperture stop S and the third lens group G3, the axial air gap d17 between the third lens group G3 and the fourth lens group G4, and the axes of the fourth lens group G4 and the fifth lens group G5 The upper air gap d20, the axial air gap d23 between the fifth lens group G5 and the sixth lens group G6, and the back focus BF change as described above. Table 7 below shows the values of the variable interval and the back focus at the respective focal lengths in the wide-angle end state, the intermediate focal length state, and the telephoto end state when focusing on infinity and focusing on a short distance.

(Table 7)
[Variable interval data]
Infinity focusing state Short-distance focusing state Wide-angle end Intermediate Telephoto end Wide-angle end Intermediate Telephoto end f 18.5 70.1 137.2 18.5 70.1 137.2
d5 1.500 29.460 43.956 1.500 29.460 43.956
d14 21.129 6.175 3.000 21.129 6.175 3.000
d15 5.970 3.536 2.000 6.367 3.851 2.459
d17 3.062 5.497 7.033 2.665 5.182 6.573
d20 2.500 6.941 8.730 2.500 6.941 8.730
d23 11.230 6.789 5.000 11.230 6.789 5.000
BF 38.02 67.56 74.63 38.02 67.56 74.63

  Table 8 below shows values corresponding to the conditional expressions in the variable magnification optical system ZL2 according to the second example.

(Table 4)
[Conditional value]
(1) f3 / f4 = 0.956
(2) (−f2) /f1=0.146
(3) f1 / fw = 4.602

  Thus, the zoom optical system ZL2 according to the second example satisfies all the conditional expressions (1) to (3).

  FIG. 5 shows various aberration diagrams of the variable magnification optical system ZL2 according to the second example when focusing at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, and shows the wide-angle end state and the intermediate focal length state. FIG. 6 is a diagram showing various aberrations when focusing at a short distance in the telephoto end state. From these respective aberration diagrams, the variable magnification optical system ZL2 according to the second example has excellent imaging performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state. It can be seen that the imaging performance is excellent even during focusing.

1 Camera (Optical Device) ZL (ZL1, ZL2) Variable magnification optical system G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group GR Subsequent lens group

Claims (11)

From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having a positive refractive power;
A subsequent lens group including at least one lens group;
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, and the distance between the second lens group and the third lens group changes, When the distance between the third lens group and the fourth lens group changes, the distance between the fourth lens group and the subsequent lens group changes, and the subsequent lens group is composed of a plurality of lens groups, The interval between each of the plurality of lens groups changes,
When focusing from infinity to a close object, the third lens group moves along the optical axis,
A variable magnification optical system characterized by satisfying the following condition:
0.60 <f3 / f4 <1.30
However,
f3: Focal length of the third lens group f4: Focal length of the fourth lens group   2. The zoom optical system according to claim 1, wherein the first lens unit moves in the object direction when zooming from the wide-angle end state to the telephoto end state.   Upon zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, 3. The variable power optical system according to claim 1, wherein a distance between the third lens group and the fourth lens group is increased, and a distance between the fourth lens group and the fifth lens group is increased. system.   The zoom lens according to any one of claims 1 to 3, wherein the third lens group includes only one positive lens or one cemented lens having a positive refractive power. Optical system.   5. The variable magnification optical system according to claim 1, wherein the most object side surface of the third lens group is an aspherical surface.   6. The variable magnification optical system according to claim 5, wherein the aspherical surface has a shape in which the positive refractive power becomes weaker as the distance from the optical axis increases. The zoom lens system according to any one of claims 1 to 6, wherein a condition of the following formula is satisfied.
0.11 <(− f2) / f1 <0.19
However,
f2: focal length of the second lens group f1: focal length of the first lens group The zoom lens system according to any one of claims 1 to 7, wherein a condition of the following formula is satisfied.
3.00 <f1 / fw <6.00
However,
f1: Focal length of the first lens group fw: Focal length of the entire system in the wide-angle end state   9. The variable magnification optical system according to claim 1, wherein at least a part of the subsequent lens group is moved so as to have a component in a direction orthogonal to the optical axis.   An optical apparatus comprising the variable magnification optical system according to claim 1. In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power A variable magnification optical system having a group and a subsequent lens group including at least one lens group,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, and the distance between the second lens group and the third lens group changes, When the distance between the third lens group and the fourth lens group changes, the distance between the fourth lens group and the subsequent lens group changes, and the subsequent lens group is composed of a plurality of lens groups, Arranged so that the interval between each of the plurality of lens groups changes,
When focusing from infinity to a short distance object, the third lens group is arranged to move along the optical axis,
A method of manufacturing a variable magnification optical system, wherein the zoom lens is disposed so as to satisfy the condition of the following formula.
0.60 <f3 / f4 <1.30
However,
f3: Focal length of the third lens group f4: Focal length of the fourth lens group

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