JP5338860B2 - OPTICAL SYSTEM, OPTICAL DEVICE HAVING THE OPTICAL SYSTEM, AND METHOD FOR PRODUCING OPTICAL SYSTEM - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical system having further high performance and favorable optical performances despite having a vibration-proof performance, an optical apparatus including the optical system, and a method for manufacturing the optical system. <P>SOLUTION: The optical system includes, in order from an object side: a first lens unit G1; a second lens unit G2 having a negative refractive power; and a third lens unit G3 having a positive refractive power. The first lens unit G1 is fixed in the direction of the optical axis with respect to the image surface and the second lens unit G2 is provided movably in a direction having a component perpendicular to the optical axis, and satisfies predetermined conditions. An antireflection film is provided on at least one surface of optical surfaces in the first lens unit and the second lens unit, and the antireflection film includes at least a layer formed by using a wet process. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

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

  Conventionally, a retrofocus lens preceded by a lens group having a negative refractive power is known as an optical system with a wide angle of view that can secure a back focus enough to be used in a single lens reflex camera or a digital camera even with a short focal length. . This lens type has been proposed with a large aperture of about F1.4 (see, for example, Patent Document 1). In recent years, not only aberration performance but also ghost and flare requirements, which are one of the factors that impair optical performance, have become increasingly demanding for such optical systems. Higher performance is required for the prevention film, and multilayer film design technology and multilayer film formation technology continue to advance to meet the demand (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 11-30743 JP 2000-356704 A

  However, the conventional optical system with a wide angle of view has a problem that the aberration correction at the time of image stabilization is not sufficient when the image stabilization mechanism is employed. At the same time, the optical surface in such an optical system also has a problem that reflected light that becomes ghost or flare is easily generated.

  The present invention has been made in view of such problems, and an optical system that further reduces ghosts and flares and has excellent anti-vibration performance, an optical apparatus including the optical system, and a method for manufacturing the optical system. The purpose is to provide.

In order to solve the above problems, the present invention provides:
From the object side,
The first lens group, the second lens group having a negative refractive power, and the third lens group having a positive refractive power substantially consist of three lens groups ,
The first lens group is fixed in the optical axis direction with respect to the image plane,
The second lens group is movably provided to have a component in a direction orthogonal to the optical axis,
The total focal length of the entire system when focusing on infinity is f, the focal length of the second lens group and the third lens group when focusing on infinity is f23 , and the focal length of the first lens group is f1. When satisfying the following conditions,
0.30 <f / f23 <0.95
−0.4 <f / f1 <0.4
An antireflection film is provided on at least one of the optical surfaces of the first lens group and the second lens group, and the antireflection film includes at least one layer formed using a wet process. An optical system is provided.
The present invention also provides:
From the object side,
The first lens group, the second lens group having a negative refractive power, and the third lens group having a positive refractive power substantially consist of three lens groups,
The first lens group is fixed in the optical axis direction with respect to the image plane,
The second lens group is movably provided to have a component in a direction orthogonal to the optical axis,
The total focal length of the entire system when focused at infinity is f, the combined focal length of the second lens group and the third lens group when focused at infinity is f23, and the focal length of the second lens group is f2. When satisfying the following conditions,
0.30 <f / f23 <0.95
−0.35 <f / f2 <−0.07
An antireflection film is provided on at least one of the optical surfaces of the first lens group and the second lens group, and the antireflection film includes at least one layer formed using a wet process. An optical system is provided.
The present invention also provides:
From the object side,
The first lens group, the second lens group having a negative refractive power, and the third lens group having a positive refractive power substantially consist of three lens groups,
The first lens group is fixed in the optical axis direction with respect to the image plane,
The second lens group is movably provided to have a component in a direction orthogonal to the optical axis,
The combined focal length of the entire system at the time of focusing on infinity is f, the combined focal length of the second lens group and the third lens group at the time of focusing on infinity is f23, and the most object side of the first lens group. When the incident height of the marginal ray on the lens surface is H1in and the incident height of the marginal ray on the lens surface closest to the object in the second lens group is H2in, the following conditions are satisfied:
0.30 <f / f23 <0.95
1.2 <H2in / H1in <3.0
An antireflection film is provided on at least one of the optical surfaces of the first lens group and the second lens group, and the antireflection film includes at least one layer formed using a wet process. An optical system is provided.

  The present invention also provides an optical apparatus comprising the optical system.

The present invention also provides:
In order from the object side, a manufacturing method of an optical system that substantially includes three lens groups by a first lens group, a second lens group having a negative refractive power, and a third lens group having a positive refractive power Because
The first lens group is disposed so as to be fixed in the optical axis direction with respect to the image plane,
The second lens group is arranged to be movable so as to have a component in a direction orthogonal to the optical axis,
The focal length of the entire system when focused at infinity is f, the combined focal length of the second lens group and the third lens group when focused at infinity is f23 , and the focal length of the first lens group is f1 . Is arranged to satisfy the following conditions,
0.30 <f / f23 <0.95
−0.4 <f / f1 <0.4
An antireflection film is provided on at least one of the optical surfaces of the first lens group and the second lens group, and the antireflection film includes at least one layer formed using a wet process. An optical system manufacturing method is provided.

  ADVANTAGE OF THE INVENTION According to this invention, a ghost and a flare can be reduced more and the optical system excellent in the anti-vibration performance, the optical apparatus provided with this optical system, and the manufacturing method of an optical system can be provided.

It is sectional drawing which shows the lens structure of the optical system concerning 1st Example. FIG. 5A is a diagram illustrating various aberrations of the optical system according to the first example, where FIG. 9A is a diagram illustrating all aberrations in the infinite focus state, and FIG. It is a coma aberration figure when performing. FIG. 6A is a diagram illustrating various aberrations of the optical system according to the first example. FIG. 9A is a diagram illustrating aberrations at an intermediate shooting distance state, and FIG. 9B is a shake correction for a rotational blur of 0.70 ° in the intermediate shooting distance state. It is a coma aberration figure when performing. It is sectional drawing which shows the lens structure of the optical system concerning 1st Example, Comprising: The figure explaining an example of a mode that the incident light ray reflects in the 1st reflected light generation surface and the 2nd reflected light generation surface It is. It is sectional drawing which shows the lens structure of the optical system concerning 2nd Example. FIG. 7A is a diagram illustrating various aberrations of the optical system according to the second example, and FIG. 9A is a diagram illustrating all aberrations in the infinite focus state, and FIG. It is a coma aberration figure when performing. FIG. 6A is a diagram illustrating various aberrations of the optical system according to Example 2, wherein FIG. 9A is a diagram illustrating aberrations at an intermediate shooting distance state, and FIG. 9B is a shake correction for a rotational shake of 0.70 ° in the intermediate shooting distance state. It is a coma aberration figure when performing. It is sectional drawing which shows the lens structure of the optical system concerning 3rd Example. FIG. 7A is a diagram illustrating various aberrations of the optical system according to the third example, FIG. 9A is a diagram illustrating various aberrations in an infinite focus state, and FIG. It is a coma aberration figure when it went. FIG. 6A is a diagram illustrating various aberrations of the optical system according to Example 3, wherein FIG. 9A is a diagram illustrating aberrations at an intermediate shooting distance state, and FIG. 9B is a shake correction for a rotational shake of 0.70 ° in the intermediate shooting distance state. It is a coma aberration figure when performing. It is sectional drawing which shows the lens structure of the optical system concerning 4th Example. FIG. 6A is a diagram illustrating various aberrations of the optical system according to Example 4, wherein FIG. 9A is a diagram illustrating various aberrations in an infinitely focused state, and FIG. It is a coma aberration figure when performing. FIG. 9A is a diagram illustrating various aberrations of the optical system according to Example 4, wherein FIG. 10A is a diagram illustrating aberrations at an intermediate shooting distance state, and FIG. 9B is a shake correction for a rotational shake of 0.70 ° in the intermediate shooting distance state. It is a coma aberration figure when performing. It is sectional drawing which shows the lens structure of the optical system concerning 5th Example. FIG. 7A is a diagram illustrating various aberrations of the optical system according to Example 5, wherein FIG. 9A is a diagram illustrating various aberrations in the infinite focus state, and FIG. It is a coma aberration figure when performing. FIG. 6A is a diagram illustrating various aberrations according to the fifth example, in which FIG. 9A is a diagram illustrating various aberrations in an intermediate shooting distance state, and FIG. 9B is a blur correction for a rotational blur of 0.70 ° in the intermediate shooting distance state. It is a coma aberration figure at the time. It is sectional drawing which shows the lens structure of the optical system concerning 6th Example. FIG. 10A is a diagram illustrating various aberrations of the optical system according to Example 6, wherein FIG. 10A is a diagram illustrating aberrations in an infinite focus state, and FIG. 9B is a shake correction for a rotational blur of 0.70 ° in an infinite photographing state. It is a coma aberration figure when performing. FIG. 10A is a diagram illustrating various aberrations of the optical system according to Example 6, wherein FIG. 10A is a diagram illustrating aberrations at an intermediate shooting distance state, and FIG. 9B is a shake correction for a rotational blur of 0.70 ° in the intermediate shooting distance state. It is a coma aberration figure when performing. It is sectional drawing which shows the lens structure of the optical system concerning 7th Example. FIG. 9A is a diagram illustrating various aberrations of the optical system according to Example 7, wherein FIG. 10A is a diagram illustrating aberrations in the infinite focus state, and FIG. 9B is a shake correction for 0.70 ° rotational blur in the infinite photographing state. It is a coma aberration figure when performing. FIG. 10A is a diagram illustrating various aberrations of the optical system according to Example 7, wherein FIG. 10A is a diagram illustrating aberrations at an intermediate shooting distance state, and FIG. 9B is a shake correction for a rotational shake of 0.70 ° in the intermediate shooting distance state. It is a coma aberration figure when performing. It is sectional drawing which shows the lens structure of the optical system concerning 8th Example. FIG. 10A is a diagram illustrating various aberrations of the optical system according to Example 8, where FIG. 10A is a diagram illustrating aberrations in the infinite focus state, and FIG. It is a coma aberration figure when performing. FIG. 10A is a diagram illustrating various aberrations of the optical system according to Example 8, wherein FIG. 10A is a diagram illustrating aberrations at an intermediate shooting distance state, and FIG. 9B is a shake correction for a rotational blur of 0.70 ° in the intermediate shooting distance state. It is a coma aberration figure when performing. 1 is a cross-sectional view of a single-lens reflex camera equipped with an optical system according to an embodiment. It is a flowchart for demonstrating the manufacturing method of the optical system concerning this embodiment. It is explanatory drawing which shows an example of the layer structure of an antireflection film. It is a graph which shows the spectral characteristic of an antireflection film. It is a graph which shows the spectral characteristics of the antireflection film concerning a modification. It is a graph which shows the incident angle dependence of the spectral characteristics of the antireflection film concerning a modification. It is a graph which shows the spectral characteristics of the anti-reflective film produced with the prior art. It is a graph which shows the incident angle dependence of the spectral characteristic of the anti-reflective film produced with the prior art.

  Hereinafter, preferred embodiments of the present application will be described with reference to the drawings. As shown in FIG. 1, the optical system SL according to this embodiment includes, in order from the object side, a first lens group G1, a second lens group G2 having a negative refractive power, and a third lens having a positive refractive power. The first lens group G1 is fixed in the optical axis direction with respect to the image plane, and the second lens group G2 moves so as to have a component in a direction orthogonal to the optical axis. It is characterized by making it.

Further, this optical system SL satisfies the following conditional expression (1).
0.30 <f / f23 <0.95 (1)
However,
f: Total focal length of the entire system when focusing on infinity,
f23: The combined focal length of the second lens group G2 and the third lens group G3 when focusing on infinity.

  In order to ensure the back focus so that a lens with a short focal length is used in a single lens reflex camera, a digital camera, etc., the pupil magnification is made larger than 1 by increasing the height of the marginal ray at the time of emission from the time of incidence of the lens. It is known that a configuration having a so-called wide converter can be effective. Here, the “marginal ray” means a ray farthest from the optical axis among rays reaching an image height of zero.

  In addition, even when there is no back focus restriction, it is effective to use the wide converter as described above in order to compensate for the shortage of peripheral light quantity that becomes conspicuous as the angle of view increases. As already described, a so-called retrofocus lens type with a large aperture of about F1.4 has been proposed.

  When introducing an anti-vibration mechanism for such an optical system with a wide angle of view, the problem is where the anti-vibration lens is inserted. Since the retrofocus lens has an asymmetrical refractive power arrangement with strong negative refractive power on the object side and strong positive refractive power on the image side, the lens groups cannot cancel out each other's aberrations. Correction of distortion and coma is particularly difficult. Therefore, it is necessary to correct aberrations as much as possible with the lens group alone. If the aberration correction unique to each lens group is not sufficient, spherical aberration, coma aberration, and decentering coma will occur when the lens group after that is shaken or when focusing on a close object. Aberration and curvature of field occur greatly. In order to correct these various aberrations, it is effective to weaken the refractive power of the first lens group G1, which has the effect of increasing the pupil magnification. However, if used in a single-lens reflex camera, the back focus is insufficient. End up.

  Therefore, the optical system SL according to the present embodiment is configured to satisfy the above-described conditional expression (1) that defines the most effective range in terms of aberration correction, pupil magnification, and back focus balance. Further, by arranging the second lens group G2, which is an anti-vibration lens group, closer to the image plane side than the first lens group G1, good aberration correction is realized.

  If the upper limit of conditional expression (1) is exceeded, the effect of the first lens group G1 as a wide converter becomes too weak, and the lens group on the image plane side requires a stronger negative refractive power. As a result, it is not preferable because it is difficult to sufficiently correct both positive curvature of field and negative distortion around the screen. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 0.80. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 0.75.

  If the lower limit value of conditional expression (1) is not reached, the effect of the first lens group G1 as a wide converter becomes too strong, and the light rays are higher in the lens group on the image plane side as measured from the optical axis. Therefore, it is difficult to correct spherical aberration, coma aberration, and the like. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.40. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.45.

  In addition, as described above, the present embodiment is characterized in that the second lens group G2, which is a vibration-proof lens group, has a negative refractive power. This takes the configuration of a retrofocus lens because the negative lens component comes first in the synthesis of the second lens group G2 and the third lens group G3. As a result, the back focus can be lengthened, the upper limit value in the conditional expression (1) is increased, and as a result, the spherical aberration and the coma aberration can be corrected well. Further, coma aberration, particularly sagittal coma aberration, can be effectively corrected for the peripheral luminous flux because the second lens group G2 has negative refractive power. As a result, good aberration correction can be realized without increasing the lens diameter. It should be noted that the above-mentioned effect can be more exerted because the lens surface closest to the object side of the second lens group has a concave surface facing the object side.

  In addition, an antireflection film is provided on at least one of the optical surfaces of the first lens group G1 and the second lens group G2 of the optical system SL according to the present embodiment, and the antireflection film is formed using a wet process. At least one layer. With this configuration, in the optical system according to the present embodiment, ghosts and flares that are generated when light from an object is reflected by an optical surface can be reduced, and high imaging performance can be achieved.

  In the optical system SL according to the present embodiment, the antireflection film is a multilayer film, and the layer formed by using the wet process is the outermost layer among the layers constituting the multilayer film. preferable. In this way, since the difference in refractive index with air can be reduced, it is possible to reduce the reflection of light and further reduce ghosts and flares.

  In the optical system SL according to this embodiment, it is preferable that the refractive index nd is 1.30 or less, where nd is the refractive index of the layer formed using the wet process. In this way, since the difference in refractive index with air can be reduced, it is possible to reduce the reflection of light and further reduce ghosts and flares.

  In the optical system SL according to the present embodiment, the optical surface provided with the antireflection film is at least one surface of the first lens group G1 and the second lens group G2, and the optical surface is an aperture stop. It is preferable that the lens surface has a concave shape as viewed from above. In the first lens group and the second lens group, reflected light is likely to be generated on a concave lens surface when viewed from the aperture stop. Therefore, by forming an antireflection film on such a lens surface, ghost and flare can be effectively prevented. Can be reduced.

  In the optical system SL according to the present embodiment, it is preferable that the concave lens surface viewed from the aperture stop provided with the antireflection film is a lens surface on the image plane side. In the first lens group and the second lens group, reflected light is likely to be generated on the lens surface on the concave image surface side when viewed from the aperture stop. Therefore, by forming an antireflection film on such a lens surface, ghost and flare are formed. Can be effectively reduced.

  In the optical system SL according to the present embodiment, it is preferable that the concave lens surface viewed from the aperture stop provided with the antireflection film is an object-side lens surface. In the first lens group and the second lens group, reflected light is likely to be generated on the concave object-side lens surface when viewed from the aperture stop. Therefore, by forming an antireflection film on such a lens surface, ghosts and flares are prevented. It can be effectively reduced.

  In the optical system SL according to the present embodiment, the optical surface provided with the antireflection film is at least one of the first lens group G1 and the second lens group G2, and the optical surface is viewed from the object side. It is preferably a concave lens surface. In the first lens group and the second lens group, reflected light is likely to be generated on a concave lens surface when viewed from the object side. Therefore, by forming an antireflection film on such a lens surface, ghosts and flares can be effectively prevented. Can be reduced.

  In the optical system SL according to this embodiment, it is preferable that the concave lens surface viewed from the object side provided with the antireflection film is a lens surface on the image plane side. In the first lens group and the second lens group, reflected light is likely to be generated on the lens surface on the concave image surface side when viewed from the object side. Therefore, by forming an antireflection film on such a lens surface, ghost and flare are formed. Can be effectively reduced.

  In the optical system SL according to the present embodiment, it is preferable that the concave lens surface viewed from the object side provided with the antireflection film is an object side lens surface. In the first lens group and the second lens group, reflected light is likely to be generated on a concave object side lens surface when viewed from the object side. Therefore, by forming an antireflection film on such a lens surface, ghost and flare are prevented. It can be effectively reduced.

  In the optical system SL according to the present embodiment, the antireflection film is not limited to a wet process, and may be formed by a dry process or the like. At this time, it is preferable that the antireflection film includes at least one layer having a refractive index of 1.30 or less. By making the antireflection film include at least one layer having a refractive index of 1.30 or less, even if the antireflection film is formed by a dry process or the like, the same effect as that obtained by using a wet process can be obtained. Can be obtained. At this time, the layer having a refractive index of 1.30 or less is preferably the most surface layer among the layers constituting the multilayer film.

In addition, it is desirable that the present optical system SL satisfies the following conditional expression (2).
−0.40 <f / f1 <0.40 (2)
However,
f: Total focal length of the entire system when focusing on infinity,
f1: Focal length of the first lens group G1.

  Conditional expression (2) is a conditional expression for defining the focal length of the first lens group G1 with respect to the focal length of the entire system of the present optical system SL. In the optical system SL, in the anti-vibration lens group, correction of decentering coma generated when moving in the substantially orthogonal direction with respect to the optical axis of the anti-vibration lens group is a big problem. In the present embodiment, by satisfying the conditional expression (2), the incident angle of the marginal light beam that is emitted from the lens group on the object side from the image stabilizing lens group (second lens group G2) and incident on the image stabilizing lens group is determined. It becomes possible to make it parallel to the optical axis, and the occurrence of decentered coma is minimized. In the retrofocus lens, since the first lens group G1 includes many lens components having negative refractive power, the aberration generated in the first lens group G1 is corrected in a balanced manner in the lens groups after the first lens group G1. Difficult to do. Therefore, it is necessary to perform sufficient aberration correction in each lens group, and when such aberration correction unique to each lens group is not sufficient, it is necessary to prevent vibrations in the subsequent lens groups or to close objects. When focusing is performed, spherical aberration, coma aberration, decentering coma aberration, and field curvature greatly occur.

  If the upper limit value of conditional expression (2) is exceeded, the angle of incidence as convergent light on the second lens group G2 becomes too large, and as a result, the second lens group G2 shifts in a direction substantially orthogonal to the optical axis. In this case, the change in the incident angle of the marginal ray becomes large, and a large amount of decentration coma occurs. Further, since the convergent light is strong with respect to the second lens group G2, as a result, the negative refractive power of the second lens group G2 becomes too strong, and the spherical aberration and the eccentric coma aberration deteriorate. Further, if the angle of light incident on the second lens group G2 as the convergent light increases by exceeding the upper limit value of the conditional expression (2), the light beam around the screen is larger than the marginal light beam with respect to the second lens group G2. And the curvature of field at the time of shifting of the second lens group G2 deteriorates, which is not preferable. Further, since the positive refractive power in the first lens group G1 is too strong, the aberration correction by the first lens group G1 alone is not sufficient, and a large negative field curvature is likely to occur. Further, as a result, a light beam having a large aberration is incident on the second lens group G2, and decentration coma aberration, field curvature at the time of decentration, astigmatism, and the like are deteriorated. Further, since the light rays around the screen exceed the upper limit value of the conditional expression (2), the light enters the second lens group G2 at a small angle. As a result, the diameter of the second lens group G2 increases, and the second lens The height at which the rays around the screen pass through the group G2 becomes too high. As a result, the eccentric coma aberration and the field curvature when shifted in a direction substantially orthogonal to the optical axis of the second lens group G2 are not preferable.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.35. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.30.

  If the lower limit value of conditional expression (2) is not reached, the angle of incidence as diverging light on the second lens group G2 becomes too large. As a result, the second lens group G2 is substantially perpendicular to the optical axis. The change in the incident angle of the marginal ray at the time of shifting becomes large, and the eccentric coma aberration is greatly generated. Further, since the negative refractive power in the first lens group G1 is too strong, the aberration correction by the first lens group G1 alone is not sufficient, and a large negative distortion tends to occur. As a result, a light beam having a large aberration is incident on the second lens group G2, and decentration coma, field curvature at the time of decentration, astigmatism, and the like are deteriorated.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to −0.35. In order to secure the effect of the present embodiment, it is preferable to set the lower limit value of conditional expression (2) to −0.30.

In addition, it is desirable that the present optical system SL satisfies the following conditional expression (3).
−0.35 <f / f2 <−0.07 (3)
However,
f: Total focal length of the entire system when focusing on infinity,
f2: focal length of the second lens group G2.

  Conditional expression (3) is a conditional expression for defining the focal length of the second lens group G2.

  If the upper limit value of conditional expression (3) is exceeded, the refractive power of the second lens group G2 becomes too weak, and the amount of movement of the second lens group G2 necessary for image stabilization control becomes larger than the appropriate value. As a result, it is difficult to correct both coma and astigmatism fluctuations when the second lens group G2 is decentered. In addition, the driving means such as an actuator for driving the second lens group G2 also becomes large. As a result, since the distance between the lens groups is compressed from an appropriate value, the refractive power of each lens group becomes too strong, and spherical aberration, coma aberration and the like are also deteriorated.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to −0.10. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to −0.12.

  If the lower limit of conditional expression (3) is not reached, the refractive power of the second lens group G2 becomes too strong. As a result, both coma and astigmatism fluctuations when the second lens group G2 is decentered. Correction becomes difficult, which is not preferable.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to −0.31. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to −0.28.

In addition, it is desirable that the present optical system SL satisfies the following conditional expression (4).
1.20 <H2in / H1in <3.00 (4)
However,
H1in: the incident height of the marginal ray on the lens surface closest to the object side of the first lens group G1,
H2in: the incident height of the marginal ray on the most object side lens surface of the second lens group G2.

  Conditional expression (4) defines the most effective range in terms of aberration correction, pupil magnification, and back focus balance. Further, by arranging the second lens group G2 closer to the image plane side than the first lens group G1, good aberration correction was realized.

  If the upper limit value of conditional expression (4) is exceeded, the effect of the first lens group G1 as a wide converter becomes too strong, and light rays pass through a higher position in the lens group on the image plane side as measured from the optical axis. It becomes difficult to correct spherical aberration, coma and the like.

  In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 2.50. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 2.20.

  If the lower limit of conditional expression (4) is not reached, the effect of the first lens group G1 as a wide converter becomes too weak, and the lens group on the image plane side requires a stronger negative refractive power. As a result, it is not preferable because it is difficult to sufficiently correct both positive curvature of field and negative distortion around the screen.

  In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 1.30. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (4) to 1.40.

  In addition, as described above, the present embodiment is characterized in that the second lens group G2, which is a vibration-proof lens group, has a negative refractive power. This takes the configuration of a retrofocus lens because the negative lens component comes first in the synthesis of the second lens group G2 and the third lens group G3. As a result, the back focus can be lengthened, the lower limit value in the conditional expression (4) can be reduced, and as a result, spherical aberration and coma aberration can be corrected well. Further, coma aberration, particularly sagittal coma aberration, can be effectively corrected for the peripheral luminous flux because the second lens group G2 has negative refractive power. As a result, good aberration correction can be realized without increasing the lens diameter. In addition, since the lens surface closest to the object side of the second lens group has a shape in which the concave surface is directed to the object side, the above-described effect can be further exhibited.

  In general, it is known that an optical surface that is concentric with respect to an aperture stop hardly generates astigmatism. As a big problem when an anti-vibration mechanism is introduced in an optical system with a wide angle of view, astigmatism at the time of decentering and fluctuations in this astigmatism can be mentioned. The reason for this is that the angle at which the peripheral image height is incident on each refractive surface of the anti-vibration lens group varies greatly during decentering, and as a result, the balance of astigmatism, coma, etc. is greatly lost and corrected. It comes from the fact that it cannot be done. Therefore, in the optical system SL according to the present embodiment, a concentric optical surface with respect to the aperture stop S is used, and a peripheral image is formed with respect to each refractive surface of the image stabilizing lens group (second lens group G2) even when decentered. The angle at which high light rays are incident was not changed greatly during eccentricity. As a result, astigmatism and coma variation at the time of decentration were corrected satisfactorily.

  Thus, in the optical system SL of the present embodiment, it is desirable that the aperture stop S is disposed on the image side with respect to the second lens group G2, and the aperture stop S is disposed in the third lens group G3. More desirably. In this case, it is desirable to arrange the lens components of the third lens group G3 before and after the aperture stop S. With this configuration, spherical aberration and coma can be favorably corrected. Here, the light beam emitted from the second lens group G2, which is the image stabilizing lens group, becomes divergent light. Therefore, when there is no lens group between the second lens group G2 and the aperture stop S, the light beam that has passed through the aperture stop S has a higher incident height with respect to the lens group on the image plane side than the aperture stop S. become. As a result, since spherical aberration and coma are deteriorated, it is desirable to have a lens component between the second lens group G2 and the aperture stop S. From the above viewpoint, it is more desirable that the lens component between the second lens group G2 and the aperture stop S has a positive refractive power. In addition, since it is possible to correct aberration before and after the aperture stop S by having a lens component on the image plane side from the aperture stop S, the third lens group G3 has a lens component before and after the aperture stop S. Is preferred. With this configuration, spherical aberration and coma can be favorably corrected. From the above viewpoint, it is more desirable that the lens component on the image plane side from the aperture stop S has a positive refractive power. In addition, a lens frame may be used instead of a member as an aperture stop.

  In the optical system SL of the present embodiment, it is desirable that the third lens group G3 moves to the object side when focusing on a short-distance object. As a focusing method for an optical system having a wide angle of view, a method of moving only the image plane side from the aperture stop S is known. However, in an optical system having a large aperture and a wide angle of view, fluctuations in spherical aberration, coma aberration, and field curvature are large and undesirable. Therefore, in the optical system SL according to the present embodiment, the third lens group G3 has lens components before and after the aperture stop S, so that spherical aberration, coma aberration, and field curvature can be obtained even when focusing on a close object. It was possible to suppress fluctuations in In addition, since there are lens components before and after the aperture stop S as described above, the spherical aberration and the coma can be favorably corrected as described above.

  FIG. 26 shows a schematic cross-sectional view of a single-lens reflex camera 1 (hereinafter simply referred to as a camera) as an optical apparatus provided with an optical system SL shown in a first embodiment to be described later. In this camera 1, light from an object (subject) (not shown) is collected by the taking lens 2 (optical system SL) and focused on the focusing screen 4 via the quick return mirror 3. The light imaged on the focusing screen 4 is reflected a plurality of times in the pentaprism 5 and guided to the eyepiece lens 6. Thus, the photographer can observe the object (subject) image as an erect image through the eyepiece 6.

  Further, when a release button (not shown) is pressed by the photographer, the quick return mirror 3 is retracted out of the optical path, and light of an object (subject) (not shown) condensed by the photographing lens 2 is captured on the image sensor 7. Form an image. Thereby, the light from the object (subject) is captured by the image sensor 7 and recorded as an object (subject) image in a memory (not shown). In this way, the photographer can shoot an object (subject) with the camera 1. The camera 1 shown in FIG. 26 may hold the optical system SL in a detachable manner, may be formed integrally with the optical system SL, or may be formed integrally with the optical system SL. Further, a camera that does not have a quick return mirror or the like may be used, and the same effect as the above camera can be achieved. The camera 1 can be mounted not only with the first embodiment described above but also with a photographic lens of another embodiment.

  Hereinafter, an outline of a method for manufacturing the optical system SL of the present embodiment will be described with reference to FIG. First, each lens is arranged and a lens group is prepared (step S100). Specifically, in the present embodiment, for example, in the case of a first example described later, the first lens group G1 has a negative meniscus lens L11 having a convex surface directed toward the object side and a convex surface directed toward the object side in order from the object side. A cemented lens of the negative meniscus lens L12 and a negative meniscus aspherical negative lens L13 having a convex surface facing the object side, a cemented lens of a biconvex positive lens L14 and a biconcave negative lens L15, and A biconvex positive lens L16 is arranged. Further, the second lens group G2 is configured by arranging, in order from the object side, a cemented lens of a biconcave negative lens L21 and a positive meniscus lens L22 having a convex surface facing the object side. The third lens group G3 includes, in order from the object side, a positive meniscus lens L31 having a convex surface facing the object side, a biconvex positive lens L32, a negative meniscus lens L33 having a convex surface facing the object side, an aperture stop S, A cemented lens of a biconcave negative lens L34 and a biconvex positive aspherical positive lens L35, a biconvex positive lens L36, and a positive meniscus lens L37 with a convex surface facing the image side are arranged. Configure.

  At this time, the first lens group G1 is disposed so as to be fixed in the optical axis direction with respect to the image plane (step S200). The second lens group G2 is movably disposed so as to have a component in a direction orthogonal to the optical axis (step S300).

  Then, the lens groups are arranged so as to satisfy the conditional expression (1) described above (step S400). Thus, the manufacture of the optical system SL according to the present embodiment is completed.

  Hereinafter, each example according to the present embodiment will be described with reference to the drawings. 1, 5, 8, 11, 14, 17, 20, and 23 are cross-sectional views illustrating the configuration of the optical system SL (SL <b> 1 to SL <b> 8) according to each example. As shown in FIGS. 1 and 5, the optical systems SL1 and SL2 according to the first and second examples have a first lens group G1 having a negative refractive power and a negative refractive power in order from the object side. It is composed of a second lens group G2 and a third lens group G3 having a positive refractive power. On the other hand, as shown in FIGS. 8, 11, 14, 17, 20, and 23, the optical systems SL3 to SL8 according to the third to eighth examples have positive refractive power in order from the object side. The first lens group G1 includes a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power.

  In each embodiment, the first lens group G1 is fixed in the optical axis direction with respect to the image plane, and the second lens group G2 moves so as to have a component in a direction substantially perpendicular to the optical axis and moves on the image plane. An anti-vibration lens group that displaces an image. The aperture stop S is disposed in the third lens group G3, has lens components having a positive refractive power before and after the aperture stop S (except for the eighth embodiment), and moves from an infinite object to a close object. At the time of focusing, the third lens group G3 moves to the object side.

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), κ is the conic constant, and An is the nth-order aspheric coefficient, and is expressed by the following equation (a). . In the following examples, “E−n” indicates “× 10 ⁻ⁿ ”.

S (y) = (y ² / r) / {1+ (1−κ × y ² / r ² ) ^1/2 }
+ A4 × y ⁴ + A6 × y ⁶ + A8 × y ⁸ (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 left side of the surface number.

[First embodiment]
FIG. 1 is a diagram illustrating a configuration of an optical system SL1 according to a first example of the present application. In the optical system SL1 of FIG. 1, the first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. A negative meniscus lens-shaped aspherical negative lens L13, a biconvex positive lens L14 and a biconcave negative lens L15, and a biconvex positive lens L16. Yes.

  The second lens group G2 includes, in order from the object side, a cemented lens of a biconcave negative lens L21 and a positive meniscus lens L22 having a convex surface facing the object side.

  The third lens group G3 includes, in order from the object side, a positive meniscus lens L31 having a convex surface directed toward the object side, a positive lens L32 having a biconvex shape, a negative meniscus lens L33 having a convex surface directed toward the object side, an aperture stop S, and a biconcave lens. The lens includes a cemented lens of a negative lens L34 having a shape and an aspheric positive lens L35 having a biconvex shape, a positive lens L36 having a biconvex shape, and a positive meniscus lens L37 having a convex surface facing the image side.

  In the first embodiment, the image side lens surface (surface number 2) of the negative meniscus lens L11 of the first lens group G1, and the object side lens surface of the biconcave negative lens L21 of the second lens group G2. An antireflection film described later is formed on (Surface Number 11).

  It should be noted that the focal length of the entire system is f, and the image blur correction coefficient (ratio of the amount of image movement on the imaging surface to the amount of movement of the moving lens group in shake correction) corrects rotational shake at an angle θ with a K lens. For this, the moving lens group for blur correction may be moved in the direction orthogonal to the optical axis by (f · tan θ) / K. In the first example, since the image stabilization coefficient is 0.306 and the focal length is 28.50 (mm), the amount of movement of the second lens group G2 for correcting the rotation blur of 0.70 °. Is 1.14 (mm).

  Table 1 below lists values of specifications of the first embodiment. In Table 1, f represents the focal length, FNO represents the F number, 2ω represents the angle of view, and Bf represents the back focus. Also, the surface number is the order of the lens surfaces from the object side along the direction of travel of the light beam, the surface interval is the interval on the optical axis from each optical surface to the next optical surface, and the refractive index and Abbe number are each The value for the d-line (λ = 587.6 nm) is shown. The total length represents the distance on the optical axis from the first surface of the lens surface to the image plane I when focusing on infinity. Here, “mm” is generally used for the focal length, the radius of curvature, the surface interval, and other length units listed in all the following specifications, but the optical system is proportionally enlarged or reduced. However, the same optical performance can be obtained, and the present invention is not limited to this. The curvature radius “∞” indicates a plane. Further, the refractive index of air of 1.0000 is omitted. The description of these symbols and the description of the specification table are the same in the following embodiments.

(Table 1) First Example
f = 28.50
FNO = 1.45
2ω = 75.6
Image height = 21.6
Total length = 133.3

Surface number Curvature radius Surface spacing Refractive index Abbe number object surface ∞
1 84.252 2.40 1.74100 52.67
2 30.284 6.24
3 57.477 2.10 1.77250 49.60
4 36.791 0.20 1.55389 38.09
* 5 32.506 12.47
6 498.367 6.33 1.74400 44.79
7 -54.700 1.30 1.52699 53.00
8 320.562 0.20
9 84.738 5.36 1.74806 50.00
10 -139.358 5.00
11 -75.418 1.30 1.48749 70.40
12 53.719 2.98 1.83400 37.16
13 118.654 (d13)
14 45.171 3.76 1.69680 55.52
15 121.944 0.20
16 39.937 6.09 1.69680 55.52
17 -136.788 0.20
18 138.447 1.30 1.62004 36.30
19 27.404 5.00
20 ∞ 6.67 Aperture stop S
21 -22.640 1.30 1.78472 25.68
22 65.850 5.67 1.77250 49.60
* 23 -59.294 1.14
24 256.664 6.00 1.74100 52.67
25 -37.599 0.20
26 -56.322 4.25 1.77250 49.61
27 -31.870 (Bf)
Image plane ∞

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1
Second lens group 11 -141.94
Third lens group 14 42.52

  In the first embodiment, the lens surfaces of the fifth surface and the 23rd surface are aspherical. The following Table 2 shows aspheric data, that is, the values of the conic constant κ and the aspheric constants A4 to A8.

(Table 2)
κ A4 A6 A8
5th surface 0.042900 -6.54648E-08 -1.07103E-09 -2.03329E-12
Side 23 -19.496500 2.12065E-06 3.80233E-08 -5.28645E-11

  In the first embodiment, the axial air distance d13 between the second lens group G2 and the third lens group G3 and the back focus Bf change during zooming. Table 3 below shows variable intervals at each focal length at infinity and at a photographing magnification of -0.0333.

(Table 3)
β Infinity -0.0333
d13 7.55 6.52
Bf 38.11 39.14

  Table 4 below shows values corresponding to the conditional expressions in the first embodiment. In Table 4, H1in represents the incident height of the marginal ray on the lens surface closest to the object side of the first lens group G1, and H2in represents the incidence of the marginal ray on the lens surface closest to the object side of the second lens group G2. F is the focal length of the entire system, f1 is the focal length of the first lens group G1, f2 is the focal length of the second lens group G2, and f23 is the second lens group G2 when focusing on infinity. And the combined focal length of the third lens group G3. The description of the above symbols is the same in the following embodiments.

(Table 4)
(1) f / f23 = 0.654
(2) f / f1 = 0.039
(3) f / f2 = -0.20
(4) H2in / H1in = 1.565

  FIG. 2A shows an aberration diagram in the infinite focus state in the first embodiment, and FIG. 3A shows an aberration diagram in the intermediate focal length state. Further, FIG. 2B shows a coma aberration diagram when blur correction is performed for 0.70 ° rotation blur in the infinite photographing state of the first embodiment, and 0.70 ° rotation blur in the intermediate focal length state. FIG. 3B shows a coma aberration diagram when blur correction is performed on the image. In each aberration diagram, FNO is the F number, NA is the numerical aperture, Y is the image height, A is the incident angle of the principal ray, D is the d-line (λ = 587.6 nm), and G is the g-line ( λ = 435.6 nm), respectively. In the aberration diagrams showing astigmatism, the solid line shows the sagittal image plane, and the broken line shows the meridional image plane. In the coma aberration, the broken line shows a sagittal lateral aberration diagram. The description of these aberration diagrams is the same in the following examples.

  As is apparent from each aberration diagram, it is clear that in the first example, various aberrations are satisfactorily corrected and the imaging performance is excellent.

  FIG. 4 shows a state where a ghost is generated by the light beam BM incident from the object side in the optical system SL1 according to the first example. In FIG. 4, when a light beam BM from the object side enters the optical system SL1 as shown in the drawing, the object-side lens surface (the first reflected light generating surface, whose surface number is the birefringent negative lens L21) 11), and the reflected light is reflected again by the image side lens surface (the second reflected light generating surface, whose surface number is 2) in the negative meniscus lens L11 of the first lens group G1, and the image surface I is reached and a ghost is generated. The first reflected light generation surface (surface number 11) is a concave lens surface when viewed from the object, and the second ghost generation surface (surface number 2) is a concave lens when viewed from the aperture stop. Surface. A ghost can be effectively reduced by forming an antireflection film corresponding to a wide incident angle in a wider wavelength range on such a surface.

[Second Embodiment]
FIG. 5 is a diagram illustrating a configuration of the optical system SL2 according to the second embodiment. In the optical system SL2 of FIG. 5, the first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. A cemented lens with a negative meniscus lens aspherical negative lens L13 facing, a cemented lens with a positive meniscus lens L14 with a convex surface facing the image side and a negative meniscus lens L15 with a convex surface facing the image side, and a biconvex shape Positive lens L16.

  The second lens group G2 includes, in order from the object side, a cemented lens of a biconcave negative lens L21 and a positive meniscus lens L22 having a convex surface facing the object side.

  The third lens group G3 includes, in order from the object side, a positive meniscus lens L31 having a convex surface directed toward the object side, a positive lens L32 having a biconvex shape, a negative meniscus lens L33 having a convex surface directed toward the object side, an aperture stop S, and a biconcave lens. The lens includes a cemented lens of a negative lens L34 having a shape and an aspheric positive lens L35 having a biconvex shape, a positive lens L36 having a biconvex shape, and a positive meniscus lens L37 having a convex surface facing the image side.

  In the second example, the image surface side lens surface (surface number 2) of the negative meniscus lens L11 of the first lens group G1 and the image surface side lens of the biconvex positive lens L16 of the first lens group G1. An antireflection film described later is formed on the surface (surface number 10).

  It should be noted that the focal length of the entire system is f, and the image blur correction coefficient (ratio of the amount of image movement on the imaging surface to the amount of movement of the moving lens group in shake correction) corrects rotational shake at an angle θ with a K lens. For this, the moving lens group for blur correction may be moved in the direction orthogonal to the optical axis by (f · tan θ) / K. In the second embodiment, since the image stabilization coefficient is 0.306 and the focal length is 27.99 (mm), the amount of movement of the second lens group G2 for correcting the rotation blur of 0.70 °. Is 1.12 (mm).

  Table 5 below shows values of specifications of the second embodiment.

(Table 5) Second Example
f = 27.99
FNO = 1.45
2ω = 76.7
Image height = 21.6
Total length = 133.3

Surface number Curvature radius Surface spacing Refractive index Abbe number object surface ∞
1 67.583 2.40 1.74100 52.67
2 30.054 6.93
3 68.341 2.10 1.77250 49.60
4 36.441 0.20 1.55389 38.09
* 5 33.585 12.50
6 -176.482 3.98 1.74400 44.79
7 -61.111 1.30 1.52599 53.31
8 -288.957 0.20
9 150.265 5.50 1.74806 50.00
10 -78.414 5.00
11 -63.966 1.30 1.48749 70.40
12 68.577 2.82 1.83400 37.16
13 186.927 (d13)
14 39.297 4.23 1.69680 55.52
15 103.599 0.20
16 39.021 6.42 1.69680 55.52
17 -148.831 0.20
18 113.771 1.30 1.61266 44.46
19 26.212 5.00
20 ∞ 7.01 Aperture stop S
21 -22.122 1.30 1.78472 25.68
22 49.850 5.35 1.77250 49.60
* 23 -53.784 1.79
24 407.632 6.00 1.75500 52.31
25 -36.823 0.20
26 -51.964 4.18 1.77250 49.61
27 -31.344 (Bf)
Image plane ∞

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 -858.75
Second lens group 11 -141.98
Third lens group 14 43.51

  In the second embodiment, the lens surfaces of the fifth surface and the 23rd surface are formed in an aspherical shape. Table 6 below shows the data of the aspheric surface, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A8.

(Table 6)
κ A4 A6 A8
5th surface 0.016000 8.67227E-07 -2.62240E-10 -1.58840E-12
Surface 23 -19.875800 -9.08714E-07 5.51987E-08 -7.97050E-11

  In the second embodiment, the axial air distance d13 between the second lens group G2 and the third lens group G3 and the back focus Bf change during zooming. Table 7 below shows variable intervals at each focal length at infinity and at a photographing magnification of -0.0333.

(Table 7)
β Infinity -0.0333
d13 7.81 6.74
Bf 38.12 39.18

  Table 8 below shows values corresponding to the conditional expressions in the second embodiment.

(Table 8)
(1) f / f23 = 0.645
(2) f / f1 = −0.033
(3) f / f2 = -0.20
(4) H2in / H1in = 1.571

  FIG. 6A shows an aberration diagram in the infinite focus state in the second embodiment, and FIG. 7A shows an aberration diagram in the intermediate focal length state. Further, FIG. 6B shows a coma aberration diagram when blur correction is performed with respect to 0.70 ° rotation blur in the infinite photographing state of the second embodiment, and 0.70 ° rotation blur in the intermediate focal length state. FIG. 7B shows a coma aberration diagram when blur correction is performed on the image.

  As is apparent from the respective aberration diagrams, it is clear that in the second embodiment, various aberrations are corrected well and the imaging performance is excellent.

[Third embodiment]
FIG. 8 is a diagram showing the configuration of the optical system SL3 according to the third example of the present application. In the optical system SL3 of FIG. 8, the first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. A negative meniscus lens-shaped aspherical negative lens L13, a positive meniscus lens L14 having a convex surface facing the image side, and a biconvex positive lens L15.

  The second lens group G2 includes, in order from the object side, a cemented lens of a biconcave negative lens L21 and a positive meniscus lens L22 having a convex surface facing the object side.

  The third lens group G3 includes, in order from the object side, a positive meniscus lens L31 having a convex surface directed toward the object side, a positive lens L32 having a biconvex shape, a negative meniscus lens L33 having a convex surface directed toward the object side, an aperture stop S, and a biconcave lens. The lens includes a cemented lens of a negative lens L34 having a shape and an aspheric positive lens L35 having a biconvex shape, a positive lens L36 having a biconvex shape, and a positive meniscus lens L37 having a convex surface facing the image side.

  In the third embodiment, the image side lens surface (surface number 2) of the negative meniscus lens L11 of the first lens group G1 and the object side lens surface of the biconcave negative lens L21 of the second lens group G2 are used. An antireflection film described later is formed on (surface number 10).

  It should be noted that the focal length of the entire system is f, and the image blur correction coefficient (ratio of the amount of image movement on the imaging surface to the amount of movement of the moving lens group in shake correction) corrects rotational shake at an angle θ with a K lens. For this, the moving lens group for blur correction may be moved in the direction orthogonal to the optical axis by (f · tan θ) / K. In the third example, since the image stabilization coefficient is 0.306 and the focal length is 28.44 (mm), the amount of movement of the second lens group G2 for correcting the rotation blur of 0.70 °. Is 1.13 (mm).

  Table 9 below shows values of specifications of the third embodiment.

(Table 9) Third Example
f = 28.44
FNO = 1.45
2ω = 75.8
Image height = 21.6
Total length = 133.3

Surface number Curvature radius Surface spacing Refractive index Abbe number object surface ∞
1 100.000 2.40 1.74100 52.67
2 30.472 6.11
3 61.820 2.10 1.77250 49.60
4 40.528 0.20 1.55389 38.09
* 5 34.996 11.06
6 -230.000 8.00 1.74397 44.85
7 -85.027 0.20
8 84.290 4.89 1.74397 44.85
9 -199.472 5.00
10 -74.412 1.30 1.48749 70.41
11 55.716 2.99 1.80100 34.96
12 131.420 (d12)
13 44.605 3.61 1.69680 55.52
14 108.329 0.20
15 38.431 6.09 1.69680 55.52
16 -159.242 0.20
17 116.847 1.30 1.62004 36.30
18 26.190 5.00
19 ∞ 6.56 Aperture stop S
20 -23.170 2.29 1.76182 26.56
21 48.664 6.00 1.77250 49.60
* 22 -61.350 1.40
23 298.511 6.00 1.72916 54.66
24 -39.601 0.20
25 -63.162 4.44 1.77250 49.61
26 -33.521 (Bf)
Image plane ∞

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 553.08
Second lens group 10 -142.23
Third lens group 13 43.02

  In the third embodiment, the lens surfaces of the fifth surface and the twenty-second surface are formed in an aspheric shape. Table 10 below shows the aspheric data, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A8.

(Table 10)
κ A4 A6 A8
5th surface -0.116100 -8.06560E-07 -1.69170E-09 -1.57780E-12
Side 22 -17.884100 2.86500E-06 2.91840E-08 -3.77560E-11

  In the third example, the axial air distance d12 between the second lens group G2 and the third lens group G3 and the back focus Bf change during zooming. Table 11 below shows variable intervals at each focal length at infinity and at a photographing magnification of -0.0333.

(Table 11)
β Infinity -0.0333
d13 7.47 6.45
Bf 38.32 39.34

  Table 12 below shows values corresponding to the conditional expressions in the third embodiment.

(Table 12)
(1) f / f23 = 0.552
(2) f / f1 = 0.053
(3) f / f2 = -0.20
(4) H2in / H1in = 1.567

  FIG. 9A shows an aberration diagram in the infinite focus state in the third embodiment, and FIG. 10A shows an aberration diagram in the intermediate focal length state. Further, FIG. 9B shows a coma aberration diagram when blur correction is performed with respect to 0.70 ° rotation blur in the infinite photographing state of the third embodiment, and 0.70 ° rotation blur in the intermediate focal length state. FIG. 10B shows a coma aberration diagram when blur correction is performed on the image.

  As is apparent from each aberration diagram, in the third example, it is clear that various aberrations are corrected favorably and the imaging performance is excellent.

[Fourth embodiment]
FIG. 11 is a diagram illustrating a configuration of an optical system SL4 according to the fourth example. In the optical system SL4 of FIG. 11, the first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. A cemented lens with an aspheric negative lens L13 having a negative meniscus lens shape facing, a cemented lens with a negative meniscus lens L14 having a convex surface facing the object side and a biconvex positive lens L15, and a positive lens L16 with a biconvex shape It is composed of

  The second lens group G2 includes, in order from the object side, a cemented lens of a biconcave negative lens L21 and a positive meniscus lens L22 having a convex surface facing the object side.

  The third lens group G3 includes, in order from the object side, a positive meniscus lens L31 having a convex surface directed toward the object side, a positive lens L32 having a biconvex shape, a negative meniscus lens L33 having a convex surface directed toward the object side, an aperture stop S, and a biconcave lens. The lens includes a cemented lens of a negative lens L34 having a shape and an aspheric positive lens L35 having a biconvex shape, a positive lens L36 having a biconvex shape, and a positive meniscus lens L37 having a convex surface facing the image side.

  In the fourth embodiment, the image surface side lens surface (surface number 2) of the negative meniscus lens L11 of the first lens group G1 and the image surface side lens surface (surface number) of the biconvex lens L16 of the first lens group G1. 10), an antireflection film described later is formed.

  It should be noted that the focal length of the entire system is f, and the image blur correction coefficient (ratio of the amount of image movement on the imaging surface to the amount of movement of the moving lens group in shake correction) corrects rotational shake at an angle θ with a K lens. For this, the moving lens group for blur correction may be moved in the direction orthogonal to the optical axis by (f · tan θ) / K. In the fourth embodiment, since the image stabilization coefficient is 0.290 and the focal length is 24.70 (mm), the amount of movement of the second lens group G2 for correcting the rotation blur of 0.70 °. Is 1.04 (mm).

  Table 13 below lists values of specifications of the fourth embodiment.

(Table 13) Fourth Example
f = 24.70
FNO = 1.44
2ω = 83.7
Image height = 21.6
Total length = 133.3

Surface number Curvature radius Surface spacing Refractive index Abbe number object surface ∞
1 70.260 2.40 1.74100 52.67
2 28.526 11.93
3 8844.268 2.10 1.77250 49.60
4 50.722 0.20 1.55389 38.09
* 5 41.921 12.50
6 298.509 2.27 1.75520 27.58
7 88.204 7.50 1.74397 44.85
8 -82.134 0.20
9 62.241 5.50 1.77250 49.61
10 -737.077 5.00
11 -96.957 1.30 1.58313 59.38
12 44.004 3.72 1.83400 37.16
13 128.781 (d13)
14 47.455 3.03 1.69680 55.52
15 90.837 0.20
16 33.070 5.62 1.68692 55.00
17 -440.765 0.20
18 66.442 1.30 1.63980 34.56
19 23.078 5.00
20 ∞ 8.45 Aperture S
21 -20.977 1.30 1.78472 25.68
22 51.753 4.09 1.77250 49.60
* 23 -48.262 1.07
24 362.304 5.96 1.74100 52.67
25 -34.691 0.20
26 -49.773 4.51 1.77250 49.61
27 -28.781 (Bf)
Image plane ∞

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 111.53
Second lens group 11 -147.13
Third lens group 14 42.48

  In the fourth embodiment, the lens surfaces of the fifth surface and the 23rd surface are formed in an aspherical shape. Table 14 below shows the data of aspheric surfaces, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A8.

(Table 14)
κ A4 A6 A8
5th surface 0.041600 -3.01610E-06 -1.30950E-10 -1.50790E-12
Surface 23 -23.208700 -6.21040E-06 1.01630E-07 -1.81570E-10

  In the fourth example, the on-axis air distance d13 between the second lens group G2 and the third lens group G3 and the back focus Bf change during zooming. Table 15 below shows variable intervals at each focal length at infinity and at a photographing magnification of -0.0333.

(Table 15)
β Infinity -0.0333
d13 6.30 5.47
Bf 31.47 32.29

  Table 16 below shows values corresponding to the conditional expressions in the fourth embodiment.

(Table 16)
(1) f / f23 = 0.570
(2) f / f1 = 0.221
(3) f / f2 = -0.17
(4) H2in / H1in = 1.823

  FIG. 12A shows an aberration diagram in the infinite focus state in the fourth embodiment, and FIG. 13A shows an aberration diagram in the intermediate focal length state. Further, FIG. 12B shows a coma aberration diagram when the blur correction is performed with respect to the rotational blur of 0.70 ° in the infinite photographing state of the fourth embodiment. The rotational blur of 0.70 ° in the intermediate focal length state is shown in FIG. FIG. 13B shows a coma aberration diagram when blur correction is performed on the image.

  As is apparent from each aberration diagram, it is clear that in the fourth example, various aberrations are corrected satisfactorily and the imaging performance is excellent.

[Fifth embodiment]
FIG. 14 is a diagram showing a configuration of an optical system SL5 according to the fifth example of the present application. In the optical system SL5 of FIG. 14, the first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. It is composed of a cemented lens with an aspheric negative lens L13 having a negative meniscus lens shape and a positive lens L14 having a biconvex shape.
The second lens group G2 includes, in order from the object side, a cemented lens of a biconcave negative lens L21 and a positive meniscus lens L22 having a convex surface facing the object side.

  The third lens group G3 includes, in order from the object side, a biconvex positive lens L31, a negative meniscus lens L32 having a convex surface facing the image side, an aperture stop S, a biconcave negative lens L33, and a biconvex aspherical surface. The lens includes a cemented lens with the positive lens L34, a positive meniscus lens L35 having a convex surface facing the image side, and a positive meniscus lens L36 having a convex surface facing the image side.

  In the fifth embodiment, the image side lens surface (surface number 2) of the negative meniscus lens L11 of the first lens group G1, and the object side lens surface of the biconcave negative lens L21 of the second lens group G2 are used. An antireflection film to be described later is formed on (surface number 8).

  It should be noted that the focal length of the entire system is f, and the image blur correction coefficient (ratio of the amount of image movement on the imaging surface to the amount of movement of the moving lens group in shake correction) corrects rotational shake at an angle θ with a K lens. For this, the moving lens group for blur correction may be moved in the direction orthogonal to the optical axis by (f · tan θ) / K. In the fifth embodiment, since the image stabilization coefficient is 0.272 and the focal length is 28.08 (mm), the amount of movement of the second lens group G2 for correcting the rotation blur of 0.70 °. Is 1.26 (mm).

  Table 17 below provides values of specifications of the fifth embodiment.

(Table 17) Fifth Example
f = 28.08
FNO = 1.84
2ω = 76.4
Image height = 21.6
Total length = 124.5

Surface number Curvature radius Surface spacing Refractive index Abbe number object surface ∞
1 69.946 2.40 1.74100 52.67
2 25.426 5.00
3 45.000 2.10 1.77250 49.60
4 26.915 0.20 1.55389 38.09
* 5 23.566 13.79
6 57.582 4.75 1.90366 31.31
7 -391.763 4.00
8 -65.539 1.30 1.55857 45.21
9 56.097 3.60 1.74397 44.85
10 836.329 (d10)
11 49.880 6.47 1.74100 52.67
12 -37.637 1.30 2.00069 25.46
13 -61.930 11.01
14 ∞ 5.00 Aperture stop S
15 -26.632 2.50 1.76182 26.56
16 69.109 5.84 1.77250 49.60
* 17 -110.000 1.44
18 -148.037 3.02 1.72916 54.66
19 -44.972 0.20
20 -87.642 3.82 1.77250 49.60
21 -31.772 (Bf)
Image plane ∞

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 -169.53
Second lens group 8 -163.95
Third lens group 11 42.15

  In the fifth embodiment, the lens surfaces of the fifth surface and the seventeenth surface are aspherical. Table 18 below shows the data of the aspheric surface, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A8.

(Table 18)
κ A4 A6 A8
5th surface 0.043300 8.68000E-07 -3.24000E-09 -2.56000E-12
17th surface 3.855700 1.23000E-05 2.12000E-09 -1.65000E-11

  In the fifth embodiment, the axial air distance d10 between the second lens group G2 and the third lens group G3 and the back focus Bf change during zooming. Table 19 below shows variable intervals at each focal length at infinity and at a photographing magnification of -0.0333.

(Table 19)
β Infinity -0.0333
d13 8.65 7.48
Bf 38.10 39.27

  Table 20 below shows values corresponding to the conditional expressions in the fifth embodiment.

(Table 20)
(1) f / f23 = 0.644
(2) f / f1 = -0.166
(3) f / f2 = -0.17
(4) H2in / H1in = 1.539

  FIG. 15A shows an aberration diagram of the fifth embodiment in the infinite focus state, and FIG. 16A shows an aberration diagram of the intermediate focal length state. Further, FIG. 15B shows a coma aberration diagram when blur correction is performed with respect to a rotational blur of 0.70 ° in the infinite photographing state of the fifth embodiment, and a rotational blur of 0.70 ° in the intermediate focal length state. FIG. 16B shows a coma aberration diagram when blur correction is performed on the image.

  As is apparent from each aberration diagram, it is clear that in the fifth example, various aberrations are corrected well and the imaging performance is excellent.

[Sixth embodiment]
FIG. 17 is a diagram showing a configuration of an optical system SL6 according to the sixth example of the present application. In the optical system SL6 of FIG. 17, the first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. It is composed of a cemented lens with an aspheric negative lens L13 having a negative meniscus lens shape, a positive meniscus lens L14 having a concave surface facing the object side, and a biconvex positive lens L15.

  The second lens group G2, in order from the object side, is a cemented lens of a positive meniscus lens L21 having a concave surface facing the object side and a negative meniscus lens L22 having a concave surface facing the object side, a biconcave negative lens L23, and It is composed of a positive meniscus lens L24 having a convex surface facing the object side.

  The third lens group G3 includes, in order from the object side, a positive meniscus lens L31 having a convex surface directed toward the object side, a positive lens L32 having a biconvex shape, a negative meniscus lens L33 having a convex surface directed toward the object side, an aperture stop S, and a biconcave lens. The lens includes a cemented lens of a negative lens L34 having a shape and an aspherical positive lens L35 having a biconvex shape, a positive lens L36 having a biconvex shape, and a positive meniscus lens L37 having a concave surface facing the object side.

  In the sixth embodiment, the image side lens surface (surface number 2) of the negative meniscus lens L11 of the first lens group G1 and the object side lens surface (surface number) of the positive meniscus lens L14 of the first lens group G1. In 6), an antireflection film described later is formed.

  It should be noted that the focal length of the entire system is f, and the image blur correction coefficient (ratio of the amount of image movement on the imaging surface to the amount of movement of the moving lens group in shake correction) corrects rotational shake at an angle θ with a K lens. For this, the moving lens group for blur correction may be moved in the direction orthogonal to the optical axis by (f · tan θ) / K. In the sixth example, since the image stabilization coefficient is 0.290 and the focal length is 29.0 (mm), the amount of movement of the second lens group G2 for correcting the rotation blur of 0.70 °. Is 1.22 (mm).

  Table 21 below provides values of specifications of the sixth embodiment.

(Table 21) Sixth Example
f = 29.00
FNO = 1.45
2ω = 74.7
Image height = 21.6
Total length = 134.1

Surface number Curvature radius Surface spacing Refractive index Abbe number object surface ∞
1 58.989 2.40 1.74100 52.67
2 29.526 6.92
3 72.211 2.10 1.77250 49.60
4 38.041 0.20 1.55389 38.09
* 5 35.056 12.50
6 -43.678 3.98 1.74400 44.78
7 -43.282 0.20
8 91.966 5.50 1.74806 50.00
9 -104.422 3.59
10 -55.000 2.51 1.48749 70.40
11 -41.353 1.50 1.51742 52.31
12 -63.431 0.20
13 -125.764 1.30 1.48749 70.40
14 41.948 0.33
15 43.787 3.35 1.83400 37.16
16 93.370 (d16)
17 40.425 4.23 1.69680 55.52
18 145.955 0.20
19 38.368 6.26 1.69680 55.52
20 -160.073 0.20
21 263.236 1.30 1.61266 44.46
22 26.332 5.00
23 ∞ 5.00 Aperture stop S
24 -25.587 1.30 1.78472 25.68
25 43.936 5.35 1.77250 49.60
* 26 -83.081 2.23
27 344.521 4.42 1.75500 52.31
28 -50.243 0.20
29 -102.612 4.73 1.77250 49.61
30 -33.734 (Bf)
Image plane ∞

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 874.69
Second lens group 10 -150.04
Third lens group 17 43.27

  In the sixth embodiment, the lens surfaces of the fifth surface and the twenty-sixth surface are aspherical. Table 22 below shows the data of aspheric surfaces, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A8.

(Table 22)
κ A4 A6 A8
5th surface 0.155400 2.09390E-07 -8.01120E-10 -1.97890E-12
26th -39.109400 5.05950E-06 2.86350E-08 -4.43890E-11

  In the sixth example, the axial air distance d16 between the second lens group G2 and the third lens group G3, and the back focus Bf change during zooming. Table 23 below shows the variable intervals at the respective focal lengths at infinity and photographing magnification of -0.0333 times.

(Table 23)
β Infinity -0.0333
d16 9.74 8.70
Bf 37.32 38.36

  Table 24 below shows values corresponding to the conditional expressions in the sixth embodiment.

(Table 24)
(1) f / f23 = 0.666
(2) f / f1 = 0.033
(3) f / f2 = 0.19
(4) H2in / H1in = 1.525

  FIG. 18A shows an aberration diagram in the infinite focus state in the sixth embodiment, and FIG. 19A shows an aberration diagram in an intermediate focal length state. Further, FIG. 18B shows a coma aberration diagram when blur correction is performed with respect to a rotational blur of 0.70 ° in the infinite photographing state of the sixth embodiment, and a rotational blur of 0.70 ° in the intermediate focal length state. FIG. 19B shows a coma aberration diagram when blur correction is performed on the image.

  As is apparent from each aberration diagram, it is clear that in the sixth example, various aberrations are corrected well and the imaging performance is excellent.

[Seventh embodiment]
FIG. 20 is a diagram showing a configuration of an optical system SL7 according to the seventh example of the present application. In the optical system SL7 of FIG. 20, the first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. A cemented lens with an aspheric negative lens L13 having a negative meniscus lens shape facing, a cemented lens with a positive meniscus lens L14 having a concave surface facing the object side and a negative meniscus lens L15 having a concave surface facing the object side, and on the object side It is composed of a positive meniscus lens L16 having a convex surface.

  The second lens group G2 includes, in order from the object side, a cemented lens of a biconcave negative lens L21 and a positive meniscus lens L22 having a convex surface facing the object side.

  The third lens group G3 includes, in order from the object side, a positive meniscus lens L31 having a convex surface directed toward the object side, a positive lens L32 having a biconvex shape, a negative meniscus lens L33 having a convex surface directed toward the object side, an aperture stop S, and a biconcave lens. The lens includes a cemented lens of a negative lens L34 having a shape and an aspherical positive lens L35 having a biconvex shape, a positive lens L36 having a biconvex shape, and a positive meniscus lens L37 having a concave surface facing the object side.

  In the seventh embodiment, the image side lens surface (surface number 2) of the negative meniscus lens L11 of the first lens group G1, and the object side lens surface of the biconcave negative lens L21 of the second lens group G2. An antireflection film described later is formed on (Surface Number 11).

  It should be noted that the focal length of the entire system is f, and the image blur correction coefficient (ratio of the amount of image movement on the imaging surface to the amount of movement of the moving lens group in shake correction) corrects rotational shake at an angle θ with a K lens. For this, the moving lens group for blur correction may be moved in the direction orthogonal to the optical axis by (f · tan θ) / K. In the seventh example, since the image stabilization coefficient is 0.30 and the focal length is 30.87 (mm), the amount of movement of the second lens group G2 for correcting the rotation blur of 0.70 °. Is 1.26 (mm).

  Table 25 below provides values of specifications of the seventh embodiment.

(Table 25) Seventh Example
f = 30.87
FNO = 1.45
2ω = 71.3
Image height = 21.6
Total length = 135.0

Surface number Curvature radius Surface spacing Refractive index Abbe number object surface ∞
1 54.000 2.40 1.74100 52.67
2 30.057 11.01
3 296.733 2.10 1.77250 49.60
4 47.966 0.20 1.55389 38.09
* 5 42.169 7.57
6 -26631.000 6.84 1.74400 44.78
7 -46.891 1.30 1.52599 53.31
8 -139.643 0.20
9 63.943 5.50 1.74806 50.00
10 5875.968 5.10
11 -80.793 1.30 1.48749 70.40
12 51.576 3.05 1.83400 37.16
13 111.029 (d13)
14 39.561 4.26 1.69680 55.52
15 122.864 0.20
16 38.831 6.04 1.69680 55.52
17 -152.489 0.20
18 214.322 1.45 1.61266 44.46
19 24.780 5.00
20 ∞ 5.07 Aperture stop S
21 -23.877 1.30 1.78472 25.68
22 40.125 6.00 1.77250 49.60
* 23 -68.316 2.73
24 270.446 6.00 1.75500 52.31
25 -43.519 0.20
26 -92.358 5.31 1.77250 49.61
27 -35.520 (Bf)
Image plane ∞

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 688.01
Second lens group 11 -146.58
Third lens group 14 43.20

  In the seventh embodiment, the lens surfaces of the fifth surface and the 23rd surface are formed in an aspherical shape. Table 26 below shows aspherical data, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspherical constants A4 to A8.

(Table 26)
κ A4 A6 A8
5th surface -0.678900 -4.81790E-07 -9.78310E-10 1.73750E-13
23rd surface -30.523200 1.70060E-06 4.19410E-08 -5.89620E-11

  In the seventh example, the on-axis air distance d13 between the second lens group G2 and the third lens group G3 and the back focus Bf change during zooming. Table 27 below shows the variable interval at each focal length at infinity and at a photographing magnification of -0.0333.

(Table 27)
β Infinity -0.0333
d13 6.39 5.28
Bf 38.32 39.43

  Table 28 below shows values corresponding to the conditional expressions in the seventh embodiment.

(Table 28)
(1) f / f23 = 0.700
(2) f / f1 = 0.045
(3) f / f2 = -0.21
(4) H2in / H1in = 1.459

  FIG. 21A shows an aberration diagram in the infinite focus state in the seventh embodiment, and FIG. 22A shows an aberration diagram in the intermediate focal length state. Further, FIG. 21B shows a coma aberration diagram when blur correction is performed with respect to a rotational blur of 0.70 ° in the infinite photographing state of the seventh embodiment, and a rotational blur of 0.70 ° in the intermediate focal length state is shown. FIG. 22B shows a coma aberration diagram when the shake correction is performed. As is apparent from the respective aberration diagrams, it is clear that in the seventh example, various aberrations are satisfactorily corrected and the imaging performance is excellent.

[Eighth embodiment]
FIG. 23 is a diagram showing a configuration of an optical system SL8 according to the eighth example of the present application. In the optical system SL8 of FIG. 23, the first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface directed toward the object side, a negative meniscus lens L12 having a convex surface directed toward the object side, and a convex surface facing the object side. A negative meniscus lens-shaped aspherical negative lens L13, a positive meniscus lens L14 having a convex surface facing the object side, and a positive meniscus lens L15 having a convex surface facing the object side.

  The second lens group G2 includes, in order from the object side, a cemented lens of a biconcave negative lens L21 and a positive meniscus lens L22 having a convex surface facing the object side.

  The third lens group G3 includes, in order from the object side, an aperture stop S, a cemented lens of a biconvex positive lens L31 and a negative meniscus lens L32 having a concave surface facing the object side, a biconcave negative lens L33, and a biconvex lens. The lens is composed of a cemented lens with an aspherical positive lens L34 having a positive lens shape, a positive meniscus lens L35 having a concave surface facing the object side, and a positive meniscus lens L36 having a concave surface facing the object side.

  In the eighth example, the image surface side lens surface (surface number 5) of the negative meniscus aspheric negative lens L13 of the first lens group G1 and the image surface side of the positive meniscus lens L22 of the second lens group G2 are used. An antireflection film described later is formed on the lens surface (surface number 12).

  It should be noted that the focal length of the entire system is f, and the image blur correction coefficient (ratio of the amount of image movement on the imaging surface to the amount of movement of the moving lens group in shake correction) corrects rotational shake at an angle θ with a K lens. For this, the moving lens group for blur correction may be moved in the direction orthogonal to the optical axis by (f · tan θ) / K. In the seventh embodiment, since the image stabilization coefficient is 0.27 and the focal length is 28.00 (mm), the amount of movement of the second lens group G2 for correcting the rotation blur of 0.70 °. Is 1.26 (mm).

  Table 29 below provides values of specifications of the eighth embodiment.

(Table 29) Eighth Example
f = 28.00
FNO = 1.84
2ω = 76.5
Image height = 21.6
Total length = 124.5

Surface number Curvature radius Surface spacing Refractive index Abbe number object surface ∞
1 100.000 2.40 1.74100 52.67
2 25.947 5.00
3 46.077 2.10 1.77250 49.60
4 28.597 0.20 1.55389 38.09
* 5 23.872 9.01
6 87.112 3.61 1.90366 31.31
7 18648.952 0.20
8 58.326 3.81 1.90366 31.31
9 250.749 4.00
10 -70.091 1.30 1.60614 37.90
11 48.211 4.02 1.74397 44.85
12 986.837 (d12)
13 ∞ 0.10 Aperture stop S
14 59.349 5.59 1.74100 52.67
15 -45.974 1.30 2.00069 25.46
16 -61.044 16.05
17 -25.065 2.50 1.84666 23.78
18 118.919 8.00 1.77250 49.60
* 19 -71.765 1.23
20 -109.608 2.93 1.72916 54.66
21 -45.839 0.20
22 -156.670 4.67 1.80400 46.57
23 -32.339 (Bf)
Image plane ∞

[Lens focal length]
Lens group Start surface Focal length 1st lens group 1 -240.33
Second lens group 10 -152.94
Third lens group 13 41.75

  In the eighth embodiment, the fifth and nineteenth lens surfaces are aspherical. Table 30 below shows the data of the aspheric surface, that is, the values of the vertex curvature radius R, the conic constant κ, and the aspheric constants A4 to A8.

(Table 30)
κ A4 A6 A8
5th surface -0.105300 -1.44211E-06 -3.86598E-09 -6.08176E-13
19th surface 3.354500 1.14404E-05 2.95647E-09 -8.75837E-12

  In the eighth example, the on-axis air distance d12 between the second lens group G2 and the third lens group G3 and the back focus Bf change during zooming. Table 31 below shows variable intervals at each focal length at infinity and at a photographing magnification of -0.0333.

(Table 31)
β Infinity -0.0333
d12 8.08 7.28
Bf 38.20 39.26

  Table 32 below shows values corresponding to the conditional expressions in the eighth embodiment.

(Table 32)
(1) f / f23 = 0.672
(2) f / f1 = -0.117
(3) f / f2 = -0.18
(4) H2in / H1in = 1.525

  FIG. 24A shows an aberration diagram of the eighth embodiment in the infinite focus state, and FIG. 25A shows an aberration diagram of the intermediate focal length state. FIG. 24 (b) shows a coma aberration diagram when blur correction is performed for 0.70 ° rotation blur in the infinite photographing state of the eighth embodiment, and 0.70 ° rotation blur in the intermediate focal length state. FIG. 25 (b) shows a coma aberration diagram when blur correction is performed on the image. As is apparent from each aberration diagram, it is clear that in the eighth example, various aberrations are corrected well and the imaging performance is excellent.

  Next, an antireflection film (also referred to as a multilayer broadband antireflection film) used in the optical systems SL1 to SL8 (hereinafter collectively referred to as SL) according to the embodiment will be described. FIG. 28 is a diagram illustrating an example of a film configuration of an antireflection film. The antireflection film 101 is composed of seven layers and is formed on the optical surface of the optical member 102 such as a lens. The first layer 101a is formed of aluminum oxide deposited by a vacuum deposition method. Further, a second layer 101b made of a mixture of titanium oxide and zirconium oxide deposited by a vacuum deposition method is further formed on the first layer 101a. Further, a third layer 101c made of aluminum oxide deposited by a vacuum deposition method is formed on the second layer 101b, and titanium oxide and zirconium oxide deposited by a vacuum deposition method are formed on the third layer 101c. A fourth layer 101d made of the mixture is formed. Furthermore, a fifth layer 101e made of aluminum oxide deposited by vacuum deposition is formed on the fourth layer 101d, and titanium oxide and zirconium oxide deposited by vacuum deposition on the fifth layer 101e. A sixth layer 101f made of the mixture is formed.

  Then, a seventh layer 101g made of a mixture of magnesium fluoride and silica is formed on the sixth layer 101f formed in this way by a wet process, and the antireflection film 101 of this embodiment is formed. For the formation of the seventh layer 101g, a sol-gel method which is a kind of wet process is used. The sol-gel method is a method in which a sol obtained by mixing raw materials is made into a non-flowable gel by hydrolysis / polycondensation reaction, etc., and this gel is heated and decomposed to obtain a product, In the production of an optical thin film, a film can be formed by applying an optical thin film material sol on the optical surface of an optical member and forming a gel film by drying and solidifying. The wet process is not limited to the sol-gel method, and a method of obtaining a solid film without going through a gel state may be used.

  Thus, the first layer 101a to the sixth layer 101f of the antireflection film 101 are formed by electron beam evaporation which is a dry process, and the seventh layer 101g which is the uppermost layer is prepared by a hydrofluoric acid / magnesium acetate method. It is formed by the following procedure by a wet process using the prepared sol solution. First, an aluminum oxide layer to be the first layer 101a, a titanium oxide-zirconium oxide mixed layer to be the second layer 101b, a third layer on the lens film formation surface (the optical surface of the optical member 102 described above) in advance using a vacuum deposition apparatus, An aluminum oxide layer to be the layer 101c, a titanium oxide-zirconium oxide mixed layer to be the fourth layer 101d, an aluminum oxide layer to be the fifth layer 101e, and a titanium oxide-zirconium oxide mixed layer to be the sixth layer 101f are formed in this order. And after taking out the optical member 102 from a vapor deposition apparatus, the thing which added the silicon alkoxide to the sol liquid prepared by the hydrofluoric acid / magnesium acetate method is apply | coated by the spin coat method, The magnesium fluoride used as the 7th layer 101g A layer made of a mixture of silica and silica is formed. The reaction formula when prepared by the hydrofluoric acid / magnesium acetate method is shown in the following formula (b).

2HF + Mg (CH3COO) 2 → MgF2 + 2CH3COOH (b)

  The sol solution used for the film formation is used for film formation after mixing raw materials and subjecting to an autoclave at 140 ° C. for 24 hours at a high temperature and pressure. The optical member 102 is completed by heat treatment at 160 ° C. for 1 hour in the air after the seventh layer 101g is formed. By using such a sol-gel method, the seventh layer 101g is formed by depositing particles having a size of several nm to several tens of nm leaving a void.

  The optical performance of the optical member having the antireflection film 101 formed as described above will be described with reference to spectral characteristics shown in FIG.

  The optical member (lens) having the antireflection film according to this embodiment is formed under the conditions shown in Table 33 below. Here, in Table 33, the reference wavelength is λ, and the layers 101a (first layer) to 101g (seventh layer) of the antireflection film 101 when the refractive index (optical member) of the substrate is 1.62, 1.74, and 1.85. The optical film thickness of each layer is determined. In Table 33, aluminum oxide is represented by Al2O3, a mixture of titanium oxide and zirconium oxide is represented by ZrO2 + TiO2, and a mixture of magnesium fluoride and silica is represented by MgF2 + SiO2.

(Table 33)
Substance Refractive index Optical film thickness Optical film thickness Optical film thickness
Medium air 1
7th layer MgF2 + SiO2 1.26 0.268λ 0.271λ 0.269λ
6th layer ZrO2 + TiO2 2.12 0.057λ 0.054λ 0.059λ
5th layer Al2O3 1.65 0.171λ 0.178λ 0.162λ
4th layer ZrO2 + TiO2 2.12 0.127λ 0.13λ 0.158λ
3rd layer Al2O3 1.65 0.122λ 0.107λ 0.08λ
Second layer ZrO2 + TiO2 2.12 0.059λ 0.075λ 0.105λ
1st layer Al2O3 1.65 0.257λ 0.03λ 0.03λ
Refractive index of substrate 1.62 1.74 1.85

  FIG. 29 shows the spectral characteristics when light rays are perpendicularly incident on an optical member in which the reference wavelength λ is 550 nm in Table 33 and the optical film thickness of each layer of the antireflection film 101 is designed.

  From FIG. 29, it can be seen that the optical member having the antireflection film 101 designed with the reference wavelength λ of 550 nm can suppress the reflectance to 0.2% or less over the entire wavelength range of 420 nm to 720 nm. Further, even in the optical member having the antireflection film 101 whose optical film thickness is designed with the reference wavelength λ as d line (wavelength 587.6 nm) in Table 33, the spectral characteristics are hardly affected, and the reference shown in FIG. It has been found that the spectral characteristics are almost the same as when the wavelength λ is 550 nm.

  Next, a modified example of the antireflection film will be described. This antireflection film consists of five layers, and similarly to Table 33, the optical film thickness of each layer with respect to the reference wavelength λ is designed under the conditions shown in Table 34 below. In this modification, the above-described sol-gel method is used for forming the fifth layer.

(Table 34)
Material Refractive index Optical film thickness Optical film thickness Medium Air 1
5th layer MgF2 + SiO2 1.26 0.275λ 0.269λ
4th layer ZrO2 + TiO2 2.12 0.045λ 0.043λ
3rd layer Al2O3 1.65 0.212λ 0.217λ
Second layer ZrO2 + TiO2 2.12 0.077λ 0.066λ
1st layer Al2O3 1.65 0.288λ 0.290λ
Refractive index of substrate 1.46 1.52

  FIG. 30 shows the spectral characteristics when light rays are perpendicularly incident on an optical member having an antireflection film in which the optical film thickness is designed with the refractive index of the substrate being 1.52 and the reference wavelength λ being 550 nm in Table 34. Yes. It can be seen from FIG. 30 that the antireflection film of the present modification has a reflectivity of 0.2% or less over the entire wavelength range of 420 nm to 720 nm. In Table 34, even an optical member having an antireflection film in which each optical film thickness is designed with the reference wavelength λ as the d-line (wavelength 587.6 nm) hardly affects the spectral characteristics, and the spectral characteristics shown in FIG. It is known to have almost the same characteristics as

  FIG. 31 shows the spectral characteristics in the case where the incident angles of the light rays to the optical member having the spectral characteristics shown in FIG. 30 are 30, 45, and 60 degrees, respectively. 30 and 31 do not show the spectral characteristics of the optical member having the antireflection film whose refractive index is 1.46 shown in Table 34, but the refractive index of the substrate is almost equal to 1.52. Needless to say, it has the following spectral characteristics.

  For comparison, FIG. 32 shows an example of an antireflection film formed only by a dry process such as a conventional vacuum deposition method. FIG. 32 shows the spectral characteristics when a light beam is perpendicularly incident on an optical member designed with an antireflection film configured with the refractive index of 1.52 of the same substrate as in Table 34 under the conditions shown in Table 35 below. FIG. 33 shows the spectral characteristics in the case where the incident angles of light rays to the optical member having the spectral characteristics shown in FIG. 32 are 30, 45, and 60 degrees, respectively.

(Table 35)
Material Refractive index Optical film thickness Medium Air 1
7th layer MgF2 1.39 0.243λ
6th layer ZrO2 + TiO2 2.12 0.119λ
5th layer Al2O3 1.65 0.057λ
4th layer ZrO2 + TiO2 2.12 0.220λ
3rd layer Al2O3 1.65 0.064λ
Second layer ZrO2 + TiO2 2.12 0.057λ
1st layer Al2O3 1.65 0.193λ
Refractive index of substrate 1.52

  When comparing the spectral characteristics of the optical member having the antireflection film according to this embodiment shown in FIGS. 29 to 31 with the spectral characteristics of the conventional example shown in FIGS. 32 and 33, the antireflection film has any incidence. It can be seen that the corner also has a lower reflectivity and has a lower reflectivity over a wider band.

  Next, an example in which the antireflection film shown in Table 33 and Table 34 is applied to the first to eighth embodiments will be described.

  In the optical system SL1 of the first example, the refractive index of the negative meniscus lens L11 of the first lens group G1 is nd = 1.74100 as shown in Table 1, and the biconcave shape of the second lens group G2 Since the negative lens L21 has a refractive index of nd = 1.48749, the antireflective film 101 having a refractive index of 1.74 corresponding to the refractive index of the substrate on the image surface side lens surface (surface number 2) of the negative meniscus lens L11. (Refer to Table 33) and use an antireflection film (see Table 34) corresponding to the refractive index of the substrate of 1.46 on the object side lens surface (surface number 11) of the biconcave negative lens L21. Thus, the reflected light from each lens surface can be reduced, and ghost and flare can be reduced.

  In the optical system SL2 of the second example, the refractive index of the negative meniscus lens L11 of the first lens group G1 is nd = 1.74100 as shown in Table 5, and the biconvex shape of the first lens group G1. Since the refractive index of the positive lens L16 is nd = 1.74806, the antireflective film 101 corresponding to the refractive index of the substrate corresponding to 1.74 on the lens surface (surface number 2) on the image plane side of the negative meniscus lens L11. (See Table 33), and an antireflection film (see Table 33) corresponding to a refractive index of the substrate of 1.74 is used on the image surface side (surface number 10) lens surface of the biconvex positive lens L16. As a result, reflected light from each lens surface can be reduced, and ghost and flare can be reduced.

  In the optical system SL3 of the third example, the refractive index of the negative meniscus lens L11 of the first lens group G1 is nd = 1.74100 as shown in Table 9, and the biconcave shape of the second lens group G2 Since the negative lens L21 has a refractive index of nd = 1.48749, the antireflective film 101 having a refractive index of 1.74 corresponding to the refractive index of the substrate on the image surface side lens surface (surface number 2) of the negative meniscus lens L11. (Refer to Table 33) and use an antireflection film (see Table 34) corresponding to the refractive index of the substrate of 1.46 on the object-side lens surface (surface number 10) of the biconcave negative lens L21. Thus, the reflected light from each lens surface can be reduced, and ghost and flare can be reduced.

  In the optical system SL4 of the fourth example, the refractive index of the negative meniscus lens L11 of the first lens group G1 is nd = 1.74100 as shown in Table 13, and the biconvex shape of the first lens group G1 Since the refractive index of the positive lens L16 is nd = 1.77250, the antireflective film 101 corresponding to the refractive index of the substrate corresponding to the refractive index of 1.74 on the lens surface (surface number 2) on the image plane side in the negative meniscus lens L11. (See Table 33), an antireflection film (see Table 33) corresponding to a refractive index of the substrate of 1.74 is used on the image surface side lens surface (surface number 10) of the biconvex positive lens L16. As a result, reflected light from each lens surface can be reduced, and ghost and flare can be reduced.

  In the optical system SL5 of the fifth example, the refractive index of the negative meniscus lens L11 of the first lens group G1 is nd = 1.74100 as shown in Table 17, and the biconcave shape of the second lens group G2 Since the negative lens L21 has a refractive index of nd = 1.55857, the antireflective film 101 having a refractive index of 1.74 corresponding to the refractive index of the substrate on the image surface side lens surface (surface number 2) of the negative meniscus lens L11. (Refer to Table 33) and use an antireflection film (see Table 34) corresponding to a refractive index of the substrate of 1.52 on the object-side lens surface (surface number 8) of the biconcave negative lens L21. Thus, the reflected light from each lens surface can be reduced, and ghost and flare can be reduced.

  In the optical system SL6 of the sixth example, the refractive index of the negative meniscus lens L11 of the first lens group G1 is nd = 1.74100 as shown in Table 21, and the positive meniscus lens of the first lens group G1. Since the refractive index of L14 is nd = 1.74400, the antireflective film 101 (Table 33) whose refractive index of the substrate corresponds to 1.74 on the lens surface (surface number 2) on the image surface side in the negative meniscus lens L11. And an antireflection film (see Table 33) corresponding to a refractive index of the substrate of 1.74 is used on the object-side lens surface (surface number 6) of the positive meniscus lens L14. Reflected light can be reduced, and ghost and flare can be reduced.

  In the optical system SL7 of the seventh example, the refractive index of the negative meniscus lens L11 of the first lens group G1 is nd = 1.74100 as shown in Table 25, and the biconcave shape of the second lens group G2 Since the negative lens L21 has a refractive index of nd = 1.48749, the antireflective film 101 having a refractive index of 1.74 corresponding to the refractive index of the substrate on the image surface side lens surface (surface number 2) of the negative meniscus lens L11. (Refer to Table 33) and use an antireflection film (see Table 34) corresponding to the refractive index of the substrate of 1.46 on the object side lens surface (surface number 11) of the biconcave negative lens L21. Thus, the reflected light from each lens surface can be reduced, and ghost and flare can be reduced.

  In the optical system SL8 of the eighth example, the refractive index of the negative meniscus lens L13 in the first lens group G1 is nd = 1.55389, as shown in Table 29, and the positive meniscus lens in the second lens group G2. Since the refractive index of L22 is nd = 1.74397, the antireflective film 101 corresponding to the refractive index of the substrate of 1.52 on the image side lens surface (surface number 5) in the negative meniscus lens L13 (Table 34). By using an antireflection film (see Table 33) corresponding to a refractive index of the substrate of 1.74 on the lens surface (surface number 12) on the image surface side of the positive meniscus lens L22. The reflected light can be reduced, and ghost and flare can be reduced.

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

  In the above description and examples, the three-group configuration optical system SL is shown. However, the above-described configuration conditions and the like can be applied to other group configurations such as a four-group configuration. 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. Further, the lens group is a portion having at least one lens separated by whether or not the lens group is separated by an air interval that changes at the time of focusing, or is moved so as to have a component substantially perpendicular to the optical axis. Show.

  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, as described above, the third lens group G3 is preferably a focusing lens group.

  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. An image stabilizing lens group to be corrected may be used. In particular, it is preferable that at least a part of the second lens group G2 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.

  In addition, in order to explain this application in an easy-to-understand manner, the configuration requirements of the embodiment have been described, but it goes without saying that the present application is not limited to this.

  As described above, according to the present invention, it is possible to provide an optical system that further reduces ghosts and flares and has excellent anti-vibration performance, an optical apparatus including the optical system, and a method for manufacturing the optical system. .

SL (SL1 to SL8) Optical system G1 First lens group G2 Second lens group G3 Third lens group
S Aperture stop 1 SLR camera (optical equipment)
101 Antireflection film 101a 1st layer 101b 2nd layer 101c 3rd layer 101d 4th layer 101e 5th layer 101f 6th layer 101g 7th layer 102 Optical member

Claims (18)

From the object side,
The first lens group, the second lens group having a negative refractive power, and the third lens group having a positive refractive power substantially consist of three lens groups ,
The first lens group is fixed in the optical axis direction with respect to the image plane,
The second lens group is movably provided to have a component in a direction orthogonal to the optical axis,
The total focal length of the entire system when focusing on infinity is f, the focal length of the second lens group and the third lens group when focusing on infinity is f23 , and the focal length of the first lens group is f1. When satisfying the following conditions,
0.30 <f / f23 <0.95
−0.4 <f / f1 <0.4
An antireflection film is provided on at least one of the optical surfaces of the first lens group and the second lens group, and the antireflection film includes at least one layer formed using a wet process. Optical system. From the object side,
The first lens group, the second lens group having a negative refractive power, and the third lens group having a positive refractive power substantially consist of three lens groups ,
The first lens group is fixed in the optical axis direction with respect to the image plane,
The second lens group is movably provided to have a component in a direction orthogonal to the optical axis,
The total focal length of the entire system when focusing on infinity is f, the synthetic focal length of the second lens group and the third lens group when focusing on infinity is f23 , and the focal length of the second lens group is f2. When satisfying the following conditions,
0.30 <f / f23 <0.95
−0.35 <f / f2 <−0.07
An antireflection film is provided on at least one of the optical surfaces of the first lens group and the second lens group, and the antireflection film includes at least one layer formed using a wet process. Optical system. From the object side,
The first lens group, the second lens group having a negative refractive power, and the third lens group having a positive refractive power substantially consist of three lens groups ,
The first lens group is fixed in the optical axis direction with respect to the image plane,
The second lens group is movably provided to have a component in a direction orthogonal to the optical axis,
The total focal length of the entire system at the time of focusing on infinity is f, the synthetic focal length of the second lens group and the third lens group at focusing on infinity is f23 , and the most object side of the first lens group is When the incident height of the marginal ray on the lens surface is H1in and the incident height of the marginal ray on the lens surface closest to the object in the second lens group is H2in , the following conditions are satisfied:
0.30 <f / f23 <0.95
1.2 <H2in / H1in <3.0
An antireflection film is provided on at least one of the optical surfaces of the first lens group and the second lens group, and the antireflection film includes at least one layer formed using a wet process. Optical system. 4. The optical system according to claim 2 , wherein the following condition is satisfied when a focal length of the first lens unit is f < b > 1.
−0.4 <f / f1 <0.4 The optical system according to claim 3 , wherein the following condition is satisfied when the focal length of the second lens group is f2.
−0.35 <f / f2 <−0.07 The antireflection film is a multilayer film,
Wherein the layer formed using a wet process, an optical system according to any one of claims 1 to 5, wherein the a layer of the most surface side among the layers constituting the multilayer film. Wherein when the refractive index of the layer formed using a wet process was nd, optical system according to any one of nd from claim 1, characterized in that 1.30 to 6. The optical surface provided with the antireflection film is at least one surface of the first lens group and the second lens group, and the optical surface is a concave lens surface when viewed from the aperture stop. optical system according to any one of claims 1 to 7, characterized. 9. The optical system according to claim 8 , wherein the concave lens surface viewed from the aperture stop is an image surface side lens surface. 9. The optical system according to claim 8 , wherein the concave lens surface viewed from the aperture stop is an object side lens surface. The optical surface provided with the antireflection film is at least one surface of the first lens group and the second lens group, and the optical surface is a concave lens surface when viewed from the object side. optical system according to any one of claims 1 to 7, characterized. The optical system according to claim 11 , wherein the lens surface having a concave shape when viewed from the object side is a lens surface on the image plane side. The optical system according to claim 11 , wherein the concave lens surface when viewed from the object side is a lens surface on the object side. The optical system according to any one of claims 1 to 13 , wherein the aperture stop is disposed on the image side of the second lens group. The optical system according to claim 14 , wherein the aperture stop is disposed in the third lens group. The optical system according to any one of claims 1 to 15 , wherein the third lens group moves toward the object side when focusing from an object at infinity to an object at a short distance. An optical apparatus comprising an optical system according to any one of claims 1 to 16. In order from the object side, a manufacturing method of an optical system that substantially includes three lens groups by a first lens group, a second lens group having a negative refractive power, and a third lens group having a positive refractive power Because
The first lens group is disposed so as to be fixed in the optical axis direction with respect to the image plane,
The second lens group is arranged to be movable so as to have a component in a direction orthogonal to the optical axis,
The focal length of the entire system when focused at infinity is f, the combined focal length of the second lens group and the third lens group when focused at infinity is f23 , and the focal length of the first lens group is f1 . Is arranged to satisfy the following conditions,
0.30 <f / f23 <0.95
−0.4 <f / f1 <0.4
An antireflection film is provided on at least one of the optical surfaces of the first lens group and the second lens group, and the antireflection film includes at least one layer formed using a wet process. A method for manufacturing an optical system.

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