JP2018156102A - Variable power optical system and optical instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable power optical system and an optical instrument having a high optical performance over the whole zoom range.SOLUTION: The variable power optical system has, successively arranged from an object side along the optical axis, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5. Upon varying powers, an interval between adjoining lens groups varies; upon varying powers, the lens group closest to the image is fixed with respect to an image plane I; upon varying powers from a wide angle end state to a telephoto end state, the first lens group G1 moves to the object side; an aperture stop S is disposed between the third lens group G3 and the fourth lens group G4; and the optical system satisfies a specified expression.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a variable magnification optical system and an optical apparatus.

  Conventionally, as a variable power optical system suitable for an interchangeable lens for a camera, a digital camera, a video camera, and the like, many lenses having a positive refractive power in the most object side lens group have been proposed (for example, Patent Document 1). reference).

JP-A-8-179214

  However, the conventional variable power optical system has a problem that it is difficult to maintain sufficiently high optical performance over the entire zoom range.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a variable magnification optical system having high optical performance over the entire zoom range and a method for manufacturing an optical apparatus.

  In order to achieve such an object, the variable magnification optical system according to the first invention includes a first lens group having positive refractive power arranged in order from the object side along the optical axis, and a negative refractive power. The second lens group, the third lens group having a positive refractive power, the fourth lens group having a positive refractive power, and the fifth lens group. When the magnification changes, the lens unit closest to the image side is fixed with respect to the image plane, and at the time of zooming from the wide-angle end state to the telephoto end state, the first lens group moves toward the object side, The aperture stop is disposed between the third lens group and the fourth lens group, and satisfies the following conditional expression.

0.480 <f3 / ft <4.0000
−0.100 <(d3t−d3w) / fw <0.330
However,
ft: focal length of the variable magnification optical system in the telephoto end state,
f3: focal length of the third lens group,
fw: focal length of the zoom optical system in the wide-angle end state,
d3w: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the wide-angle end state;
d3t: Distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the telephoto end state.

  A variable magnification optical system according to a second invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, arranged in order from the object side along the optical axis, and a positive It has a third lens group having a refractive power, a fourth lens group having a positive refractive power, and a fifth lens group. At the time of zooming, the interval between adjacent lens groups changes, and at the time of zooming, The lens unit closest to the image side is fixed with respect to the image plane. At the time of zooming from the wide-angle end state to the telephoto end state, the first lens unit moves to the object side, and the fourth lens unit includes an aperture stop. And satisfies the following conditional expression:

0.480 <f3 / ft <4.0000
−0.100 <(d3t−d3w) / fw <0.330
0.730 <(− f2) / fw <1.800
However,
ft: focal length of the variable magnification optical system in the telephoto end state,
f3: focal length of the third lens group,
fw: focal length of the zoom optical system in the wide-angle end state,
d3w: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the wide-angle end state;
d3t: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the telephoto end state;
f2: focal length of the second lens group.

  A variable magnification optical system 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, arranged in order from the object side along the optical axis, and a positive It has a third lens group having a refractive power, a fourth lens group having a positive refractive power, and a fifth lens group. At the time of zooming, the interval between adjacent lens groups changes, and at the time of zooming, The lens group closest to the image side is fixed with respect to the image plane, and the aperture stop is disposed between the third lens group and the fourth lens group, and satisfies the following conditional expression.

0.480 <f3 / ft <4.0000
−0.100 <(d3t−d3w) / fw <0.330
3.000 <fR / fw <9.500
However,
ft: focal length of the variable magnification optical system in the telephoto end state,
f3: focal length of the third lens group,
fw: focal length of the zoom optical system in the wide-angle end state,
d3w: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the wide-angle end state;
d3t: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the telephoto end state;
fR: focal length of the lens group closest to the image side.

  A variable magnification optical system according to a fourth aspect of the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, arranged in order from the object side along the optical axis, and a positive It has a third lens group having a refractive power, a fourth lens group having a positive refractive power, and a fifth lens group. At the time of zooming, the interval between adjacent lens groups changes, and at the time of zooming, The most image side lens unit is fixed with respect to the image plane, and the fourth lens unit has an aperture stop, and satisfies the following conditional expression.

0.480 <f3 / ft <4.0000
−0.100 <(d3t−d3w) / fw <0.330
3.000 <fR / fw <9.500
0.730 <(− f2) / fw <1.800
However,
ft: focal length of the variable magnification optical system in the telephoto end state,
f3: focal length of the third lens group,
fw: focal length of the zoom optical system in the wide-angle end state,
d3w: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the wide-angle end state;
d3t: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the telephoto end state;
fR: focal length of the lens group closest to the image side,
f2: focal length of the second lens group.

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

  According to the present invention, it is possible to provide a variable magnification optical system and an optical apparatus that have high optical performance over the entire zoom range.

(W), (M), and (T) are cross-sectional views of the zoom optical system according to the first example in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. (A), (b), and (c) are graphs showing various aberrations during focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable magnification optical system according to the first example. It is. (A), (b), and (c) are respectively when focusing on a short-distance object in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the zoom optical system according to the first example (between object images). It is a diagram of various aberrations at a distance of 1.00 m). (A), (b), and (c) respectively perform image blur correction at the time of focusing on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the first example. FIG. 6 is a meridional lateral aberration diagram when performed (shift amount of an anti-vibration lens group = 0.1 mm). (W), (M), and (T) are cross-sectional views of the zoom optical system according to the second example in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. (A), (b), and (c) are graphs showing various aberrations when focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable magnification optical system according to the second example. It is. (A), (b), and (c) are respectively when focusing on a short-distance object in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the zoom optical system according to the second example (between object images). It is a diagram of various aberrations at a distance of 1.00 m). (A), (b), and (c) respectively perform image blur correction at the time of focusing on an object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the second example. FIG. 6 is a meridional lateral aberration diagram when it is performed (shift amount of the image stabilizing lens group = 0.1 mm). (W), (M), and (T) are sectional views of the zoom optical system according to the third example in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. (A), (b), and (c) are graphs showing various aberrations when focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable magnification optical system according to the third example. It is. (A), (b), and (c) are respectively when focusing on a short-distance object (between object images) in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable magnification optical system according to the third example. It is a diagram of various aberrations at a distance of 1.00 m). (A), (b), and (c) respectively perform image blur correction at the time of focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable magnification optical system according to the third example. FIG. 6 is a meridional lateral aberration diagram when it is performed (shift amount of the image stabilizing lens group = 0.1 mm). It is a figure which shows the structure of the camera carrying the variable magnification optical system which concerns on this embodiment. It is a figure which shows the outline of the manufacturing method of the variable magnification optical system which concerns on this embodiment.

Hereinafter, embodiments will be described with reference to the drawings. As shown in FIG. 1, the variable magnification optical system ZL according to the present embodiment has 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. It has a second lens group G2, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5. At the time of zooming, the first lens The distance between the group G1 and the second lens group G2, the distance between 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, and the fourth lens group G4 and the fifth lens group G4. In this configuration, the distance from the lens group G5 changes. With this configuration, zooming can be realized, and variations in distortion, astigmatism, and spherical aberration associated with zooming can be suppressed.

  In the zoom optical system ZL according to the present embodiment, the lens group closest to the image side (corresponding to the fifth lens group G5 in FIG. 1) is substantially fixed with respect to the image plane I during zooming. With this configuration, it is possible to optimize the change in the height of the off-axis light beam that passes through the lens group closest to the image during zooming, and to suppress variations in distortion and astigmatism. In addition, the lens barrel structure constituting the variable magnification optical system ZL according to the present embodiment can be simplified, decentering due to manufacturing errors, etc. can be suppressed, and is caused by the decentering of the lens group closest to the image side. It is possible to suppress the eccentric coma aberration and the tilt of the peripheral image plane.

  The variable magnification optical system ZL according to the present embodiment satisfies the following conditional expression (1).

0.480 <f3 / ft <4.0000 (1)
However,
ft: focal length of the variable magnification optical system ZL in the telephoto end state,
f3: focal length of the third lens group G3.

  Conditional expression (1) defines an appropriate focal length range of the third lens group G3. By satisfying conditional expression (1), it is possible to suppress fluctuations in spherical aberration and astigmatism during zooming.

  If the corresponding value of the conditional expression (1) is less than the lower limit value, it becomes difficult to suppress fluctuations in spherical aberration and astigmatism occurring in the third lens group G3 during zooming, and high optical performance cannot be realized.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.570.

  If the corresponding value of conditional expression (1) exceeds the upper limit value, the variation of astigmatism occurring in the fourth lens group G4 at the time of zooming becomes excessive, and high optical performance cannot be realized.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 3.200. In order to further secure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (1) to 2.400.

  The variable magnification optical system ZL according to the present embodiment satisfies the following conditional expression (2).

−0.100 <(d3t−d3w) / fw <0.330 (2)
However,
fw: focal length of the variable magnification optical system ZL in the wide-angle end state,
d3w: the distance on the optical axis from the most image side lens surface of the third lens group G3 to the most object side lens surface of the fourth lens group G4 in the wide-angle end state;
d3t: Distance on the optical axis from the most image-side lens surface of the third lens group G3 to the most object-side lens surface of the fourth lens group G4 in the telephoto end state.

Conditional expression (2) defines an appropriate range of change in the distance between the third lens group G3 and the fourth lens group G4 at the time of zooming. By satisfying conditional expression (2), it is possible to suppress fluctuations in astigmatism during zooming.

  If the corresponding value of conditional expression (2) is less than the lower limit, it becomes difficult to suppress fluctuations in astigmatism that occurs in the third lens group G3 during zooming, and high optical performance cannot be realized.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to −0.080.

  When the corresponding value of the conditional expression (2) exceeds the upper limit value, the change in height from the optical axis of the off-axis light beam passing through the fourth lens group G4 at the time of zooming becomes large, and the fourth lens group G4 Astigmatism fluctuations that occur are excessive, and high optical performance cannot be realized.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.275.

  In the zoom optical system ZL according to this embodiment, it is preferable that the most image side lens unit has a positive refractive power. With this configuration, the use magnification of the lens group closest to the image side is smaller than the same magnification, and the lens group closer to the object side than the lens group closest to the image side (for example, in FIG. 1, the first lens group G1 to the fourth lens group). The combined focal length of G4 can be made relatively large. As a result, the influence of decentration coma aberration caused by the decentration of the lenses, which occurs in the lens group on the object side rather than the lens group on the most image side at the time of manufacturing, can be relatively suppressed, and high optical performance Can be realized.

  The zoom optical system ZL according to the present embodiment preferably satisfies the following conditional expression (3).

3.000 <fR / fw <9.500 (3)
However,
fR: focal length of the lens group closest to the image side.

  Conditional expression (3) defines an appropriate focal length range of the lens group closest to the image side. By satisfying conditional expression (3), it is possible to suppress fluctuations in astigmatism and distortion during zooming.

  If the corresponding value of conditional expression (3) is below the lower limit, it becomes difficult to suppress fluctuations in astigmatism and distortion occurring in the lens group closest to the image side during zooming, and high optical performance cannot be realized.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to 4.200.

  When the corresponding value of the conditional expression (3) exceeds the upper limit value, the astigmatism variation generated in the lens unit closer to the object side than the lens unit closest to the image side is corrected by the lens unit closest to the image side during zooming. It is difficult to achieve high optical performance.

  In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to 7.600.

  The variable magnification optical system ZL according to the present embodiment preferably satisfies the following conditional expression (4).

0.730 <(− f2) / fw <1.800 (4)
However,
f2: focal length of the second lens group G2.

  Conditional expression (4) defines an appropriate focal length range of the second lens group G2. By satisfying conditional expression (4), it is possible to suppress variations in spherical aberration and astigmatism during zooming.

  If the corresponding value of conditional expression (4) is less than the lower limit, it becomes difficult to suppress variations in spherical aberration and astigmatism that occur in the second lens group G2 during zooming, and high optical performance cannot be realized.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 0.900. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 1.065.

  When the corresponding value of the conditional expression (4) exceeds the upper limit value, it is necessary to increase the change in the distance between the first lens group G1 and the second lens group G2 at the time of zooming in order to ensure a predetermined zooming ratio. is there. As a result, since the ratio of the diameters of the axial light beams passing through the first lens group G1 and the second lens group G2 changes greatly, the variation in spherical aberration at the time of zooming becomes excessive, and high optical performance cannot be realized.

  In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 1.600.

  The variable magnification optical system ZL according to the present embodiment preferably satisfies the following conditional expression (5).

0.470 <f4 / ft <0.900 (5)
However,
f4: focal length of the fourth lens group G4.

  Conditional expression (5) defines an appropriate focal length range of the fourth lens group G4. By satisfying conditional expression (5), it is possible to suppress variations in spherical aberration and astigmatism during zooming.

  If the corresponding value of conditional expression (5) is less than the lower limit, it becomes difficult to suppress variations in spherical aberration and astigmatism that occur in the fourth lens group G4 during zooming, and high optical performance cannot be realized.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 0.530.

  When the corresponding value of the conditional expression (5) exceeds the upper limit value, it is necessary to increase the amount of movement of the fourth lens group G4 with respect to the image plane I at the time of zooming to ensure a predetermined zoom ratio. As a result, since the diameter of the axial light beam passing through the fourth lens group G4 changes greatly, the variation of spherical aberration at the time of zooming becomes excessive, and high optical performance cannot be realized.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 0.720.

  In the zoom optical system ZL according to the present embodiment, it is preferable that the first lens group G1 moves to the object side during zooming from the wide-angle end state to the telephoto end state. With this configuration, it is possible to suppress a change in height from the optical axis of the off-axis light beam that passes through the first lens group G1 during zooming. As a result, it is possible to suppress fluctuations in astigmatism during zooming that are generated by the first lens group G1.

  In the zoom optical system ZL according to the present embodiment, it is preferable that the distance 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. With this configuration, the magnification of the second lens group G2 can be increased when zooming from the wide-angle end state to the telephoto end state, so that the focal length of all the lens groups can be increased, Variations in spherical aberration and astigmatism during magnification can be suppressed.

  In the zoom optical system ZL according to the present embodiment, it is preferable that the distance between the second lens group G2 and the third lens group G3 is reduced when zooming from the wide-angle end state to the telephoto end state. With this configuration, since the magnification of the third lens group G3 to the fifth lens group G5 can be increased when zooming from the wide-angle end state to the telephoto end state, the focal lengths of all the lens groups are increased. It is possible to reduce the variation of spherical aberration and astigmatism during zooming.

  The zoom optical system ZL according to the present embodiment preferably satisfies the following conditional expression (6).

0.350 <(d1t-d1w) / ft <0.800 (6)
However,
d1w: distance on the optical axis from the most image side lens surface of the first lens group G1 to the most object side lens surface of the second lens group G2 in the wide-angle end state;
d1t: Distance on the optical axis from the most image side lens surface of the first lens group G1 to the most object side lens surface of the second lens group G2 in the telephoto end state.

  Conditional expression (6) defines an appropriate range of a change in the distance between the first lens group G1 and the second lens group G2 during zooming. By satisfying conditional expression (6), it is possible to suppress fluctuations in astigmatism and coma upon zooming.

  When the corresponding value of the conditional expression (6) is below the lower limit value, it is necessary to increase the refractive power of the first lens group G1 and the second lens group G2 in order to realize a predetermined zoom ratio. Then, it becomes difficult to suppress fluctuations in astigmatism and coma at the time of zooming that occur in the second lens group G2, and high optical performance cannot be realized.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (6) to 0.380.

  When the corresponding value of the conditional expression (6) exceeds the upper limit value, the change in height from the optical axis of the off-axis light beam passing through the first lens group G1 at the time of zooming becomes large, so that the first lens group G1 Astigmatism fluctuations that occur are excessive, and high optical performance cannot be realized.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (6) to 0.650.

  The zoom optical system ZL according to the present embodiment preferably satisfies the following conditional expression (7).

0.200 <(d2w−d2t) / ft <0.700 (7)
However,
d2w: the distance on the optical axis from the most image side lens surface of the second lens group G2 to the most object side lens surface of the third lens group G3 in the wide-angle end state;
d2t: Distance on the optical axis from the most image side lens surface of the second lens group G2 to the most object side lens surface of the third lens group G3 in the telephoto end state.

  Conditional expression (7) defines an appropriate range of the change in the distance between the second lens group G2 and the third lens group G3 during zooming. By satisfying conditional expression (7), it is possible to suppress variations in spherical aberration and astigmatism during zooming.

  When the corresponding value of the conditional expression (7) is below the lower limit value, it is necessary to increase the refractive power of the second lens group G2 and the third lens group G3 in order to realize a predetermined zoom ratio. As a result, it becomes difficult to suppress variations in spherical aberration and astigmatism during zooming that occur in the second lens group G2 and the third lens group G3, and high optical performance cannot be realized.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (7) to 0.270.

  When the corresponding value of the conditional expression (7) exceeds the upper limit value, the change in height from the optical axis of the off-axis light beam passing through the second lens group G2 at the time of zooming becomes large, so that the second lens group G2 Astigmatism fluctuations that occur are excessive, and high optical performance cannot be realized.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (7) to 0.550.

  In the zoom optical system ZL according to the present embodiment, it is preferable that the fourth lens group G4 has an aperture stop S. With this configuration, it is possible to suppress fluctuations in astigmatism that occurs in the fourth lens group G4 during zooming, and to realize high optical performance.

  In the zoom optical system ZL according to the present embodiment, it is preferable that the aperture stop S is disposed between the third lens group G3 and the fourth lens group G4. With this configuration, the change in height from the optical axis of the off-axis light beam passing through the third lens group G3 and the fourth lens group G4 during zooming is reduced, and is generated in the third lens group G3 and the fourth lens group G4. Astigmatism fluctuations can be suppressed, and high optical performance can be realized.

  In the variable magnification optical system ZL according to the present embodiment, it is preferable that the third lens group G3 moves along the optical axis during focusing. With this configuration, the amount of movement during focusing on the telephoto side is suppressed, and fluctuation in height from the optical axis of the light beam incident on the third lens group G3, which is the focusing lens group on the telephoto side, is suppressed. Variation in spherical aberration and astigmatism can be suppressed.

  In the variable magnification optical system ZL according to the present embodiment, it is preferable that the third lens group G3 moves toward the image side when focusing from an object at infinity to an object at a short distance. With this configuration, it is possible to focus only with the third lens group G3, and it is possible to suppress variations in spherical aberration and astigmatism during focusing and to realize high optical performance.

  According to the variable magnification optical system ZL according to the present embodiment having the above-described configuration, a variable magnification optical system having high optical performance over the entire zoom range can be realized.

Next, a camera (optical apparatus) including the above-described variable magnification optical system ZL will be described with reference to FIG. As shown in FIG. 13, the camera 1 is an interchangeable lens camera (so-called mirrorless camera) provided with the above-described variable magnification optical system ZL as the photographing lens 2. In this camera 1, light from an object (subject) (not shown) is collected by the taking lens 2, and 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. This allows the photographer to
The subject can be observed via the EVF 4. When a release button (not shown) is pressed by the photographer, the subject image generated 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.

  Here, the variable magnification optical system ZL according to this embodiment mounted as the photographing lens 2 in the camera 1 is high over the entire zoom range due to its characteristic lens configuration, as can be seen from each example described later. Has optical performance. Therefore, according to the camera 1, it is possible to realize an optical device having high optical performance over the entire zoom range.

  Even when the above-described variable magnification optical system ZL is mounted on a single-lens reflex camera that has a quick return mirror and observes a subject with a finder optical system, the same effect as the camera 1 can be obtained. Further, even when the above-described variable magnification optical system ZL is mounted on a video camera, the same effects as the camera 1 can be obtained.

  Next, a method for manufacturing the above-described variable magnification optical system ZL will be outlined 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 positive refractive power that are arranged in order from the object side along the optical axis in the lens barrel. Each lens is arranged so as to have a third lens group, a fourth lens group having positive refractive power, and a fifth lens group (step ST10). At this time, at the time of zooming, the distance between the first lens group G1 and the second lens group G2, the distance between the second lens group G2 and the third lens group G3, and the distance between the third lens group G3 and the fourth lens group G4. The lenses are arranged such that the distance between the fourth lens group G4 and the fifth lens group G5 changes (step ST20). Further, at the time of zooming, each lens is arranged so that the most image side lens group is substantially fixed with respect to the image plane (step ST30). Then, each lens is arranged so as to satisfy the following conditional expressions (1) and (2) (step ST40).

0.480 <f3 / ft <4.0000 (1)
−0.100 <(d3t−d3w) / fw <0.330 (2)
However,
ft: focal length of the variable magnification optical system ZL in the telephoto end state,
f3: focal length of the third lens group G3,
fw: focal length of the variable magnification optical system ZL in the wide-angle end state,
d3w: the distance on the optical axis from the most image side lens surface of the third lens group G3 to the most object side lens surface of the fourth lens group G4 in the wide-angle end state;
d3t: Distance on the optical axis from the most image-side lens surface of the third lens group G3 to the most object-side lens surface of the fourth lens group G4 in the telephoto end state.

As an example of the lens arrangement in the present embodiment, in the variable magnification optical system ZL shown in FIG. 1, the first lens group G1 having positive refractive power is convex on the object side in order from the object side along the optical axis. A cemented lens of a negative meniscus lens L11 facing the lens and a biconvex positive lens L12, and a positive meniscus lens L13 having a convex surface facing the object side are arranged in the lens barrel. As the second lens group G2 having negative refractive power, 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 biconcave negative lens L22, and a biconvex positive lens The lens L23 is disposed in the lens barrel. As the third lens group G3 having positive refractive power, a biconvex positive lens L31 is arranged in the lens barrel. As a fourth lens group G4 having a positive refractive power, a cemented lens of a negative meniscus lens L41 having a convex surface facing the object side and a biconvex positive lens L42 in order from the object side along the optical axis, and a biconvex lens A cemented lens of a positive lens L43 having a shape and a negative meniscus lens L44 having a concave surface facing the object side, and a negative meniscus lens L45 having a convex surface facing the object side are arranged in the lens barrel. As the fifth lens group G5, a positive meniscus lens L51 having a concave surface directed toward the object side is disposed in the lens barrel. Each lens is arranged in the lens barrel so as to satisfy the conditional expressions (1) and (2) (the corresponding value of the conditional expression (1) is 1.031 and the corresponding value of the conditional expression (2) is 0.215).

  According to the zoom optical system manufacturing method according to the present embodiment, it is possible to manufacture a zoom optical system ZL having high optical performance over the entire zoom range.

  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.

  Each reference code for 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, d-line (wavelength 587.5620 nm) and g-line (wavelength 435.8350 nm) are selected as the calculation targets of the aberration characteristics.

  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 . The secondary aspherical coefficient A2 is 0, and the description is omitted.

X (y) = (y ² / R) / {1+ (1−κ × y ² / R ² ) ^1/2 } + A4y ⁴ + A6y ⁶ + A8y ⁸ + A10y ¹⁰ + A12y ¹² (a)

  In [Various data] in the table, when focusing on an object at infinity, f is the focal length of the entire lens system, FNO is the F number, ω is the half field angle (unit is “°”), Y is the image height, φ Is the aperture diameter of the aperture stop S, TL is the total optical length (distance on the optical axis from the first surface to the image plane I when focusing on an object at infinity), and BF is the back focus (most image when focusing on an object at infinity). The distance on the optical axis from the surface side lens surface to the image plane I) is shown. W represents the wide-angle end state, M represents the intermediate focal length state, and T represents the telephoto end state.

  In [Variable interval data] in the table, variable interval values Di in the wide-angle end state (W), the intermediate focal length state (M), and the telephoto end state (T) at the time of focusing on infinity are shown. Di represents a variable interval between the i-th surface and the (i + 1) -th surface.

In [Focus group movement amount at the time of focusing] in the table, the focusing lens group (third lens group G3) from the infinite focusing state to the short-distance focusing state (object-image distance 1.00 m). Indicates the amount of movement. Here, the moving direction of the focusing lens group is positive when moving toward the image side. The shooting distance indicates the distance from the object to the image plane I.

  In [Lens Group Data] in the table, the starting surface and focal length of each lens group are shown.

  “Values corresponding to conditional expressions” in the table indicate values corresponding to the conditional expressions (1) to (7).

  Hereinafter, in all the specification values, “mm” is generally used for the focal length f, curvature radius R, surface distance D, and other lengths, etc. unless otherwise specified, but the optical system 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. As shown in FIG. 1, the variable magnification optical system 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 lens group G1. From the second lens group G2 having refractive power, the third lens group G3 having positive refractive power, the fourth lens group G4 having positive refractive power, and the fifth lens group G5 having positive refractive power Become. An aperture stop S is provided between the third lens group G3 and the fourth lens group G4, and the aperture stop S constitutes the fourth lens group G4. The fifth lens group G5 is the most image side lens group.

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

  The second lens group G2 is composed of a negative meniscus lens L21 having a convex surface facing the object side, a biconcave negative lens L22, and a biconvex positive lens L23 arranged in order from the object side along the optical axis. Become. The negative meniscus lens L21 is a composite aspherical lens made of resin and glass in which the object-side lens surface is aspherical.

  The third lens group G3 is composed of a biconvex positive lens L31. The positive lens L31 is a glass mold aspheric lens in which the object-side and image-side lens surfaces are aspherical.

  The fourth lens group G4 is a fourth A sub-lens composed of a cemented lens of a negative meniscus lens L41 having a convex surface directed toward the object side and a biconvex positive lens L42, which are arranged in order from the object side along the optical axis. 4B sub-lens group including group G4A, a cemented lens of a biconvex positive lens L43 and a negative meniscus lens L44 having a concave surface directed toward the object side, and a negative meniscus lens L45 having a convex surface directed toward the object side G4B. The negative meniscus lens L44 is a glass mold aspheric lens having an aspheric lens surface on the image side.

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

  In the zoom optical system ZL1 according to the present embodiment, the air gap between the first lens group G1 and the second lens group G2 and the second lens group G2 and the third lens at the time of zooming from the wide-angle end state to the telephoto end state. The first lens group G1 so that the air gap between the group G3, the air gap between the third lens group G3 and the fourth lens group G4, and the air gap between the fourth lens group G4 and the fifth lens group G5 change. The fourth lens group G4 moves along the optical axis. The fifth lens group G5 is fixed with respect to the image plane I.

  Specifically, the first lens group G1 to the fourth lens group G4 move to the object side. The aperture stop S moves to the object side integrally with the fourth lens group G4.

  Thereby, at the time of zooming, the air gap between the first lens group G1 and the second lens group G2 increases, the air gap between the second lens group G2 and the third lens group G3 decreases, and the third lens group G3. And the fourth lens group G4 increase, and the air distance between the fourth lens group G4 and the fifth lens group G5 increases. Further, the air gap between the aperture stop S and the third lens group G3 increases.

  Focusing is performed by moving the third lens group G3 along the optical axis. Specifically, when focusing from an object at infinity to a near object, the third lens group G3 is moved to the image side along the optical axis.

  When image blur occurs, the image blur correction (anti-vibration) on the image plane I is performed by moving the fourth A sub-lens group G4A as a vibration-proof lens group so as to have a component perpendicular to the optical axis.

  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 ∞
1 132.7211 1.6000 1.846660 23.80
2 54.2419 4.5271 1.589130 61.22
3 -1401.4921 0.1000
4 36.9475 4.0173 1.696800 55.52
5 200.3945 D5 (variable)
* 6 510.0000 0.0800 1.560930 36.64
7 288.8364 1.0000 1.816000 46.59
8 8.8676 4.8531
9 -23.6529 0.9000 1.696800 55.52
10 37.1909 0.7644
11 21.6553 2.6218 1.808090 22.74
12 -149.6082 D12 (variable)
* 13 31.4469 1.4931 1.589130 61.15
* 14 -454.8143 D14 (variable)
15 ∞ 1.7118 (Aperture)
16 17.8093 0.9000 1.834000 37.18
17 10.8731 2.4554 1.497820 82.57
18 -36.9740 1.5005
19 14.0517 2.3992 1.518230 58.82
20 -15.0205 1.0034 1.851350 40.13
* 21 -25.0875 0.2985
22 23.6629 2.4328 1.902650 35.73
23 8.6520 D23 (variable)
24 -29.8985 2.0872 1.617720 49.81
25 -17.6129 BF
Image plane ∞

[Aspherical data]
6th surface κ = 1.00000
A4 = 1.30134E-05
A6 = 5.20059E-08
A8 = -1.38176E-09
A10 = 6.06866E-12
A12 = 0.00000E + 00

13th surface κ = 0.3322
A4 = 5.55970E-05
A6 = 3.96498E-07
A8 = 3.97804E-09
A10 = 0.00000E + 00
A12 = 0.00000E + 00

14th surface κ = 4.0000
A4 = 9.44678E-05
A6 = 5.47705E-07
A8 = 1.37698E-23
A10 = 0.00000E + 00
A12 = 0.00000E + 00

21st surface κ = -1.0412
A4 = 8.07840E-06
A6 = -1.60525E-07
A8 = -3.84486E-09
A10 = 0.00000E + 00
A12 = 0.00000E + 00

[Various data]
Scaling ratio 4.71
W M T
f 10.29845 32.00216 48.49978
FNO 3.60 5.06 5.79
ω 39.76047 13.63173 9.16599
Y 8.00 8.00 8.00
φ 7.80 8.30 8.30
TL 79.34243 95.80944 105.57918
BF 13.25602 13.25602 13.25602

[Variable interval data]
W M T
f 10.29845 32.00216 48.49978
D5 1.80000 16.93666 22.35926
D12 18.49692 5.54052 1.80069
D14 3.61695 3.90524 5.82908
D23 5.42688 19.42534 25.58847

[Focus group movement during focusing]
W M T
Distance between objects 1.00m 1.00m 1.00m
Travel distance 0.2652 0.7481 1.2334

[Lens group data]
Group number Group first surface Group focal length G1 1 57.25524
G2 6 -11.09964
G3 13 49.98341
G4 15 28.96589
G5 24 65.16201

[Conditional expression values]
Conditional expression (1) f3 / ft = 1.031
Conditional expression (2) (d3t-d3w) /fw=0.215
Conditional expression (3) fR / fw = 6.326
Conditional expression (4) (-f2) / fw = 1.078
Conditional expression (5) f4 / ft = 0.597
Conditional expression (6) (d1t-d1w) /ft=0.424
Conditional expression (7) (d2w−d2t) /ft=0.344

  From Table 1, it can be seen that the variable magnification optical system ZL1 according to the present example satisfies the conditional expressions (1) to (7).

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 variable magnification optical system ZL1 according to the first example when focusing on infinity. (A) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state. FIG. 3 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, coma aberration) when the variable magnification optical system ZL1 according to the first example is in focus at a short distance object (distance between object images is 1.00 m). (A) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. FIG. 4 is a meridional lateral aberration diagram when image blur correction is performed at the time of focusing on infinity of the variable magnification optical system ZL1 according to the first example (shift amount of the image stabilizing lens group = 0.1 mm). a) shows the wide-angle end state, (b) shows the intermediate focal length state, and (c) shows the telephoto end state. In this example, the optical performance during image stabilization is shown by a meridional lateral aberration diagram corresponding to the center of the screen and an image height of ± 5.6 mm, as shown in FIGS.

  In each aberration diagram, FNO is the F number, NA is the numerical aperture of the light beam emitted from the lens on the most image side, A is the light beam incident angle, that is, the half field angle (unit is “°”), and H0 is the object height (the unit is “ mm "), Y indicates the image height. d represents the aberration at the d-line, and g represents the aberration at the g-line. Those without d and g indicate aberrations at the d-line. In the spherical aberration diagram, the solid line indicates spherical aberration. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. In the coma aberration diagram, the solid line indicates the coma aberration in the meridional direction. Note that the same reference numerals as in this embodiment are used in the aberration diagrams of each embodiment described later.

  As is apparent from the respective aberration diagrams shown in FIGS. 2 to 4, the variable magnification optical system ZL1 according to the first example extends from the wide-angle end state to the telephoto end state and from the infinity in-focus state to the short-distance focusing state. It can be seen that various aberrations are satisfactorily corrected over the focal state and high optical performance is achieved. Further, it can be seen that the image formation performance is high at the time of image blur correction.

(Second embodiment)
A second embodiment will be described with reference to FIGS. As shown in FIG. 5, the variable magnification optical system ZL (ZL2) according to the second example includes a first lens group G1 having a positive refractive power and arranged in order from the object side along the optical axis. From the second lens group G2 having refractive power, the third lens group G3 having positive refractive power, the fourth lens group G4 having positive refractive power, and the fifth lens group G5 having positive refractive power Become. An aperture stop S is provided between the third lens group G3 and the fourth lens group G4, and the aperture stop S constitutes the fourth lens group G4. The fifth lens group G5 is the most image side lens group.

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

  The second lens group G2 includes a negative meniscus lens L21 having a convex surface facing the object side, a negative meniscus lens L22 having a concave surface facing the object side, and a biconvex positive lens arrayed in order from the object side along the optical axis. Lens L23. The negative meniscus lens L21 is a composite aspherical lens made of resin and glass in which the object-side lens surface is aspherical.

  The third lens group G3 is composed of a positive meniscus lens L31 having a convex surface directed toward the object side. The positive meniscus lens L31 is a glass mold aspheric lens having an aspheric lens surface on the object side.

  The fourth lens group G4 is a fourth A sub-lens composed of a cemented lens of a negative meniscus lens L41 having a convex surface directed toward the object side and a biconvex positive lens L42, which are arranged in order from the object side along the optical axis. A cemented lens of the group G4A, a biconvex positive lens L43 and a negative meniscus lens L44 having a concave surface facing the object side, a negative meniscus lens L45 having a convex surface facing the object side, and a positive meniscus having a convex surface facing the object side A fourth B sub-lens group G4B including a cemented lens with the lens L46 is included. The negative meniscus lens L44 is a glass mold aspheric lens having an aspheric lens surface on the image side.

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

  In the zoom optical system ZL2 according to the present embodiment, at the time of zooming, the air gap between the first lens group G1 and the second lens group G2, the air gap between the second lens group G2 and the third lens group G3, and the third The first lens group G1 to the fourth lens group G4 are optical axes so that the air gap between the lens group G3 and the fourth lens group G4 and the air gap between the fourth lens group G4 and the fifth lens group G5 respectively change. Move along. The fifth lens group G5 is fixed with respect to the image plane I.

  Specifically, at the time of zooming from the wide-angle end state to the telephoto end state, the first lens group G1, the third lens group G3, and the fourth lens group G4 move to the object side. The second lens group G2 moves toward the image side from the wide-angle end state to the intermediate focal length state, and moves toward the object side from the intermediate focal length state to the telephoto end state. The aperture stop S moves to the object side integrally with the fourth lens group G4.

  Thereby, at the time of zooming, the air gap between the first lens group G1 and the second lens group G2 increases, the air gap between the second lens group G2 and the third lens group G3 decreases, and the third lens group G3. And the fourth lens group G4 decrease from the wide-angle end state to the intermediate focal length state, increase from the intermediate focal length state to the telephoto end state, and the air interval between the fourth lens group G4 and the fifth lens group G5. Will increase. The air gap between the aperture stop S and the third lens group G3 decreases from the wide-angle end state to the intermediate focal length state, and increases from the intermediate focal length state to the telephoto end state.

Focusing is performed by moving the third lens group G3 along the optical axis. Specifically, when focusing from an object at infinity to a near object, the third lens group G3 is moved to the image side along the optical axis.

  When image blur occurs, the image blur correction (anti-vibration) on the image plane I is performed by moving the fourth A sub-lens group G4A as a vibration-proof lens group so as to have a component perpendicular to the optical axis.

  Table 2 below shows the values of each item in the second embodiment. Surface numbers 1 to 26 in Table 2 correspond to the optical surfaces m1 to m26 shown in FIG.

(Table 2)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 144.9435 1.6000 1.846660 23.80
2 57.9139 4.6578 1.696800 55.52
3 -430.8049 0.1000
4 49.1887 3.5211 1.696800 55.52
5 158.0589 D5 (variable)
* 6 504.4641 0.0800 1.560930 36.64
7 234.1101 1.0000 1.834810 42.73
8 9.4881 5.5305
9 -17.0787 0.9276 1.741000 52.76
10 -1027.3916 1.0145
11 34.5727 2.6835 1.808090 22.74
12 -53.1261 D12 (variable)
* 13 24.3966 1.6530 1.588870 61.13
14 296.0192 D14 (variable)
15 ∞ 1.5000 (Aperture)
16 17.3960 0.9000 1.883000 40.66
17 11.0000 2.8505 1.497820 82.57
18 -48.0307 1.5000
19 12.4669 2.8380 1.487490 70.32
20 -14.1721 0.9000 1.851080 40.12
* 21 -35.5823 0.1000
22 19.0885 0.9000 1.883000 40.66
23 7.1245 1.8774 1.620040 36.40
24 8.9496 D24 (variable)
25 -30.0000 3.6500 1.696800 55.52
26 -19.7882 BF
Image plane ∞

[Aspherical data]
6th surface κ = -1.9998
A4 = 2.80199E-05
A6 = -2.77907E-07
A8 = 2.24720E-09
A10 = -8.56636E-12
A12 = 0.00000E + 00

13th surface κ = 1.7623
A4 = -2.39838E-05
A6 = -7.89804E-08
A8 = 2.79454E-09
A10 = 0.00000E + 00
A12 = 0.00000E + 00

21st surface κ = -0.1893
A4 = -9.56775E-06
A6 = -6.24519E-07
A8 = 1.01416E-08
A10 = 0.00000E + 00
A12 = 0.00000E + 00

[Various data]
Scaling ratio 6.59
W M T
f 10.29976 39.99987 67.89953
FNO 3.64 5.06 5.81
ω 39.73502 10.92213 6.56887
Y 8.00 8.00 8.00
φ 8.60 9.90 9.90
TL 89.92002 109.96784 121.58326
BF 13.25085 13.25085 13.25085

[Variable interval data]
W M T
f 10.29976 39.99987 67.89953
D5 1.80000 24.18110 32.41506
D12 25.02141 7.23672 2.58202
D14 4.80996 3.66893 5.14775
D24 5.25391 21.84636 28.40370

[Focus group movement during focusing]
W M T
Distance between objects 1.00m 1.00m 1.00m
Travel 0.3072 0.9550 1.8445

[Lens group data]
Group number Group first surface Group focal length G1 1 68.26199
G2 6 -12.46728
G3 13 45.04911
G4 15 40.55521
G5 25 72.75019

[Conditional expression values]
Conditional expression (1) f3 / ft = 0.663
Conditional expression (2) (d3t−d3w) /fw=0.033
Conditional expression (3) fR / fw = 7.063
Conditional expression (4) (− f2) /fw=1.210
Conditional expression (5) f4 / ft = 0.597
Conditional expression (6) (d1t-d1w) /ft=0.451
Conditional expression (7) (d2w−d2t) /ft=0.330

  From Table 2, it can be seen that the variable magnification optical system ZL2 according to the present example satisfies the conditional expressions (1) to (7).

FIG. 6 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma diagram and magnification chromatic aberration diagram) at the time of focusing on infinity of the variable magnification optical system ZL2 according to the second example. (A) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state. FIG. 7 is a diagram illustrating various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, coma aberration) when the variable magnification optical system ZL2 according to the second example is in focus at a short distance object distance (1.00 m between object images). (A) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. FIG. 8 is a meridional lateral aberration diagram when image blur correction is performed at the time of focusing on infinity of the variable magnification optical system ZL2 according to the second example (shift amount of the image stabilizing lens group = 0.1 mm). a) shows the wide-angle end state, (b) shows the intermediate focal length state, and (c) shows the telephoto end state. In this example, as shown in FIGS. 8A to 8C, the optical performance during image stabilization is shown by a meridional lateral aberration diagram corresponding to the center of the screen and an image height of ± 5.6 mm.

  As is apparent from the aberration diagrams shown in FIGS. 6 to 8, the variable magnification optical system ZL2 according to the second example is in the range from the wide-angle end state to the telephoto end state, and from the infinity in-focus state to the short-distance focusing state. It can be seen that various aberrations are satisfactorily corrected over the focal state and high optical performance is achieved. Further, it can be seen that the image formation performance is high at the time of image blur correction.

(Third embodiment)
A third embodiment will be described with reference to FIGS. 9 to 12 and Table 3. FIG. As shown in FIG. 9, the variable magnification optical system ZL (ZL3) according to the third example includes a first lens group G1 having positive refractive power arranged in order from the object side along the optical axis, and a negative lens group G1. A second lens group G2 having a refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, a fifth lens group G5 having a negative refractive power, The sixth lens group G6 has a positive refractive power. An aperture stop S is provided between the third lens group G3 and the fourth lens group G4, and the aperture stop S constitutes the fourth lens group G4. The sixth lens group G6 is the most image side lens group.

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

  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. Lens L23. The negative lens L22 is a glass mold aspheric lens having an aspheric lens surface on the object side.

  The third lens group G3 is composed of a biconvex positive lens L31. The positive lens L31 is a glass mold aspheric lens having an aspheric lens surface on the object side.

The fourth lens group G4 is a fourth A sub-lens composed of a cemented lens of a negative meniscus lens L41 having a convex surface directed toward the object side and a biconvex positive lens L42, which are arranged in order from the object side along the optical axis. It comprises a group G4A and a fourth-B sub-lens group G4B including a cemented lens of a biconvex positive lens L43 and a negative meniscus lens L44 having a concave surface directed toward the object side. The negative meniscus lens L44 is a glass mold aspheric lens having an aspheric lens surface on the image side.

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

  The sixth lens group G6 includes a positive meniscus lens L61 having a concave surface directed toward the object side.

  In the zoom optical system ZL3 according to the present embodiment, at the time of zooming, the air gap between the first lens group G1 and the second lens group G2, the air gap between the second lens group G2 and the third lens group G3, The air gap between the lens group G3 and the fourth lens group G4, the air gap between the fourth lens group G4 and the fifth lens group G5, and the air gap between the fifth lens group G5 and the sixth lens group G6 are changed. Further, the first lens group G1 to the fifth lens group G5 move along the optical axis. The sixth lens group G6 is fixed with respect to the image plane I.

  Specifically, at the time of zooming from the wide-angle end state to the telephoto end state, the first lens group G1, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 move to the object side. The second lens group G2 moves toward the image side from the wide-angle end state to the intermediate focal length state, and moves toward the object side from the intermediate focal length state to the telephoto end state. The aperture stop S moves to the object side integrally with the fourth lens group G4.

  Thereby, at the time of zooming, the air gap between the first lens group G1 and the second lens group G2 increases, the air gap between the second lens group G2 and the third lens group G3 decreases, and the third lens group G3. And the fourth lens group G4 decrease from the wide-angle end state to the intermediate focal length state, increase from the intermediate focal length state to the telephoto end state, and the air interval between the fourth lens group G4 and the fifth lens group G5. Increases, and the air gap between the fifth lens group G5 and the sixth lens group G6 increases. The air gap between the aperture stop S and the third lens group G3 decreases from the wide-angle end state to the intermediate focal length state, and increases from the intermediate focal length state to the telephoto end state.

  Focusing is performed by moving the third lens group G3 along the optical axis. Specifically, when focusing from an object at infinity to a near object, the third lens group G3 is moved to the image side along the optical axis.

  When image blur occurs, the image blur correction (anti-vibration) on the image plane I is performed by moving the fourth A sub-lens group G4A as a vibration-proof lens group so as to have a component perpendicular to the optical axis.

  Table 3 below shows values of various specifications in the third example. Surface numbers 1 to 24 in Table 3 correspond to the optical surfaces m1 to m24 shown in FIG.

(Table 3)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 270.7698 1.6000 1.84666 23.80
2 63.2289 4.7857 1.58913 61.22
3 -180.7756 0.1000
4 38.2772 3.3872 1.69680 55.52
5 162.5542 D5 (variable)
6 222.4687 0.9000 1.72916 54.61
7 8.6817 5.3065
* 8 -19.5238 0.9000 1.69680 55.52
9 33.5766 0.1038
10 19.7682 2.5354 1.84666 23.80
11 434.3570 D11 (variable)
* 12 26.1871 1.7281 1.58887 61.13
13 -76.6701 D13 (variable)
14 ∞ 1.7051 (Aperture)
15 16.6153 0.9002 1.83400 37.18
16 9.9827 2.6157 1.49782 82.57
17 -36.7432 1.5000
18 16.2913 2.2592 1.51823 58.82
19 -17.2434 0.9000 1.85108 40.12
* 20 -31.3248 D20 (variable)
21 28.0868 0.9000 1.90265 35.72
22 9.2493 D22 (variable)
23 -37.3758 2.2000 1.61772 49.81
24 -18.1325 BF
Image plane ∞

[Aspherical data]
8th surface κ = 1.0000
A4 = 2.09316E-05
A6 = -8.10797E-07
A8 = 2.75349E-08
A10 = -4.70299E-10
A12 = 2.62880E-12

12th surface κ = 1.0000
A4 = -4.37334E-05
A6 = 3.04727E-07
A8 = -6.38106E-09
A10 = 0.00000E + 00
A12 = 0.00000E + 00

20th surface κ = 1.0000
A4 = 2.28740E-05
A6 = -3.19205E-07
A8 = -1.46715E-10
A10 = 0.00000E + 00
A12 = 0.00000E + 00

[Various data]
Scaling ratio 4.71
W M T
f 10.30000 32.00000 48.51858
FNO 3.53 5.00 5.72
ω 39.75617 13.57625 9.11928
Y 8.00 8.00 8.00
φ 8.20 8.80 8.80
TL 80.36557 92.30690 103.19342
BF 13.30097 13.30097 13.30097

[Variable interval data]
W M T
f 10.30000 32.00000 48.51858
D5 1.80638 15.63570 22.37678
D11 18.74841 4.51318 2.11693
D13 5.83635 4.73970 5.51292
D20 1.50000 3.72584 3.97118
D22 4.84649 16.06454 21.58766

[Focus group movement during focusing]
W M T
Distance between objects 1.00m 1.00m 1.00m
Travel 0.1896 0.4064 0.6618

[Lens group data]
Group number Group first surface Group focal length G1 1 60.91787
G2 6 -9.90833
G3 12 33.35587
G4 14 15.48045
G5 21 -15.63253
G6 23 54.62879

[Conditional expression values]
Conditional expression (1) f3 / ft = 0.687
Conditional expression (2) (d3t−d3w) /fw=−0.031
Conditional expression (3) fR / fw = 5.304
Conditional expression (4) (-f2) / fw = 0.962
Conditional expression (6) (d1t-d1w) /ft=0.424
Conditional expression (7) (d2w−d2t) /ft=0.343

  From Table 3, it can be seen that the variable magnification optical system ZL3 according to the present example satisfies the conditional expressions (1) to (4), (6), and (7).

FIG. 10 is a diagram illustrating various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma diagram, and chromatic aberration diagram of magnification) of the zoom optical system ZL3 according to the third example when focusing on infinity. (A) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state. FIG. 11 is a diagram illustrating various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, coma aberration) when the variable magnification optical system ZL3 according to the third example is in focus at a short distance object (distance between object images is 1.00 m). (A) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. FIG. 12 is a meridional lateral aberration diagram when image blur correction is performed at the time of focusing on infinity of the variable magnification optical system ZL3 according to Example 3 (shift amount of the image stabilizing lens group = 0.1 mm). a) shows the wide-angle end state, (b) shows the intermediate focal length state, and (c) shows the telephoto end state. In this example, the optical performance during image stabilization is shown by a meridional lateral aberration diagram corresponding to the center of the screen and an image height of ± 5.6 mm, as shown in FIGS.

  As is apparent from the aberration diagrams shown in FIGS. 10 to 12, the variable magnification optical system ZL3 according to the third example is in the range from the wide-angle end state to the telephoto end state, and from the infinite focus state to the short distance focus state. It can be seen that various aberrations are satisfactorily corrected over the focal state and high optical performance is achieved. Further, it can be seen that the image formation performance is high at the time of image blur correction.

  According to each of the embodiments described above, a variable magnification optical system having high optical performance over the entire zoom range can be realized.

  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. The following contents can be adopted as appropriate as long as the optical performance of the variable magnification optical system of the present application is not impaired.

  As numerical examples of the variable magnification optical system ZL according to the present embodiment, the five-group and six-group configurations are shown, but the present invention is not limited to this, and can be applied to other group configurations (for example, seven groups). It is. Specifically, a configuration in which a lens or a lens group is added closest to the object side or a configuration in which a lens or a lens group is added closest to the 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 the variable magnification optical system ZL according to the present embodiment, in order to perform focusing from an object at infinity to an object at a short distance, a part of the lens group, the entire lens group, or a plurality of lens groups are in focus. Alternatively, it may be configured to move in the optical axis direction. In the present embodiment, an example in which the third lens group G3 is a focusing lens group has been described, but at least a part of the second lens group G2, at least a part of the third lens group G3, and a fourth lens group G4. At least one part or at least one part of the fifth lens group G5 may be a focusing lens group. Further, such a focusing lens group can be applied to autofocus, and is also suitable for driving by an autofocus motor (for example, an ultrasonic motor).

  In the variable magnification optical system ZL according to the present embodiment, any lens group or a partial lens group is moved as a vibration-proof lens group so as to have a component in a direction perpendicular to the optical axis, or includes the optical axis. Although the 4A sub lens group G4A has been described as an example of a configuration that corrects image blur caused by camera shake or the like by rotating (swinging) in the in-plane direction, the present invention is not limited to this. For example, the 3rd lens group At least a part of G3, at least a part of the fourth lens group G4, and at least a part of the fifth lens group G5 may be set as an anti-vibration lens group.

  In the variable magnification optical system ZL according to the present embodiment, 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.

  In the variable magnification optical system ZL according to the present embodiment, it is preferable that the aperture stop S is disposed in the fourth lens group G4 or in the vicinity thereof. The role of the lens may be substituted by a lens frame without providing a member as an aperture stop.

In the variable magnification optical system ZL according to the present embodiment, each lens surface is provided with an antireflection film having high transmittance in a wide wavelength region in order to reduce flare and ghost and achieve high contrast and high optical performance. May be.

ZL (ZL1 to ZL3) Variable magnification optical system G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group G4A Fourth A sublens group G4B Fourth B sublens group G5 Fifth lens group G6 Sixth Lens group S Aperture stop I Image surface 1 Camera (optical equipment)

Claims (14)

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; A fourth lens group having refractive power and a fifth lens group;
During zooming, the distance between adjacent lens groups changes,
At the time of zooming, the lens group closest to the image side is fixed with respect to the image plane,
When zooming from the wide-angle end state to the telephoto end state, the first lens group moves toward the object side,
An aperture stop is disposed between the third lens group and the fourth lens group,
A zoom optical system characterized by satisfying the following conditional expression:
0.480 <f3 / ft <4.0000
−0.100 <(d3t−d3w) / fw <0.330
However,
ft: focal length of the variable magnification optical system in the telephoto end state,
f3: focal length of the third lens group,
fw: focal length of the zoom optical system in the wide-angle end state,
d3w: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the wide-angle end state;
d3t: Distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group 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; A fourth lens group having refractive power and a fifth lens group;
During zooming, the distance between adjacent lens groups changes,
At the time of zooming, the lens group closest to the image side is fixed with respect to the image plane,
When zooming from the wide-angle end state to the telephoto end state, the first lens group moves toward the object side,
The fourth lens group has an aperture stop,
A zoom optical system characterized by satisfying the following conditional expression:
0.480 <f3 / ft <4.0000
−0.100 <(d3t−d3w) / fw <0.330
0.730 <(− f2) / fw <1.800
However,
ft: focal length of the variable magnification optical system in the telephoto end state,
f3: focal length of the third lens group,
fw: focal length of the zoom optical system in the wide-angle end state,
d3w: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the wide-angle end state;
d3t: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the telephoto end state;
f2: focal length of the second lens group. 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; A fourth lens group having refractive power and a fifth lens group;
During zooming, the distance between adjacent lens groups changes,
At the time of zooming, the lens group closest to the image side is fixed with respect to the image plane,
An aperture stop is disposed between the third lens group and the fourth lens group,
A zoom optical system characterized by satisfying the following conditional expression:
0.480 <f3 / ft <4.0000
−0.100 <(d3t−d3w) / fw <0.330
3.000 <fR / fw <9.500
However,
ft: focal length of the variable magnification optical system in the telephoto end state,
f3: focal length of the third lens group,
fw: focal length of the zoom optical system in the wide-angle end state,
d3w: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the wide-angle end state;
d3t: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the telephoto end state;
fR: focal length of the lens group closest to the image 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, arranged in order from the object side along the optical axis; A fourth lens group having refractive power and a fifth lens group;
During zooming, the distance between adjacent lens groups changes,
At the time of zooming, the lens group closest to the image side is fixed with respect to the image plane,
The fourth lens group has an aperture stop,
A zoom optical system characterized by satisfying the following conditional expression:
0.480 <f3 / ft <4.0000
−0.100 <(d3t−d3w) / fw <0.330
3.000 <fR / fw <9.500
0.730 <(− f2) / fw <1.800
However,
ft: focal length of the variable magnification optical system in the telephoto end state,
f3: focal length of the third lens group,
fw: focal length of the zoom optical system in the wide-angle end state,
d3w: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the wide-angle end state;
d3t: the distance on the optical axis from the most image side lens surface of the third lens group to the most object side lens surface of the fourth lens group in the telephoto end state;
fR: focal length of the lens group closest to the image side,
f2: focal length of the second lens group. The zoom lens system according to claim 1 or 3, wherein the following conditional expression is satisfied.
0.730 <(− f2) / fw <1.800
However,
f2: focal length of the second lens group. The zoom lens system according to claim 1 or 2, wherein the following conditional expression is satisfied.
3.000 <fR / fw <9.500
However,
fR: focal length of the lens group closest to the image side.   The zoom optical system according to any one of claims 1 to 6, wherein the third lens group moves along an optical axis during focusing.   The variable magnification optical system according to claim 1, wherein the lens group closest to the image side has a positive refractive power. The zoom lens system according to claim 1, wherein the following conditional expression is satisfied.
0.470 <f4 / ft <0.900
However,
f4: focal length of the fourth lens group.   The zooming according to any one of claims 1 to 9, wherein an interval between the first lens group and the second lens group is increased when zooming from the wide-angle end state to the telephoto end state. Optical system.   The zooming according to any one of claims 1 to 10, wherein an interval between the second lens group and the third lens group decreases when zooming from a wide-angle end state to a telephoto end state. Optical system. The zoom lens system according to any one of claims 1 to 11, wherein the following conditional expression is satisfied.
0.350 <(d1t-d1w) / ft <0.800
However,
d1w: the distance on the optical axis from the most image side lens surface of the first lens group to the most object side lens surface of the second lens group in the wide-angle end state;
d1t: Distance on the optical axis from the most image side lens surface of the first lens group to the most object side lens surface of the second lens group in the telephoto end state. The zoom lens system according to any one of claims 1 to 12, wherein the following conditional expression is satisfied.
0.200 <(d2w−d2t) / ft <0.700
However,
d2w: distance on the optical axis from the most image side lens surface of the second lens group to the most object side lens surface of the third lens group in the wide-angle end state;
d2t: Distance on the optical axis from the most image side lens surface of the second lens group to the most object side lens surface of the third lens group in the telephoto end state.   An optical apparatus comprising the variable magnification optical system according to any one of claims 1 to 13.

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