JP7114041B2 - Variable magnification imaging optical system - Google Patents

Description

The present invention relates to a variable power imaging optical system having a vibration reduction function for use in imaging devices such as digital cameras and video cameras.

Conventionally, Patent Documents 1 to 3 disclose a variable-magnification imaging optical system having a half angle of view at the telephoto end of 5° or less.

JP 2013-235218 A Japanese Patent Application Laid-Open No. 2015-191008 JP 2016-080825 A

2. Description of the Related Art In recent years, variable-magnification imaging optical systems used in imaging devices such as digital still cameras are required to have high optical performance over the entire zoom range and to be compact and lightweight. In addition, F The number is required to be bright and large aperture.

In addition, especially in variable-magnification imaging optical systems with a narrow angle of view at the telephoto end, camera shake and other vibrations are likely to cause blurring of captured images. is required to have an anti-vibration function for correcting blurring of a captured image by displacing the . Furthermore, if the variable magnification imaging optical system has a vibration reduction function, the vibration reduction lens group must be small in diameter and light in weight in order to avoid increasing the size of the actuator that drives the vibration reduction lens group. It is

By the way, in recent years, moving image shooting using a digital still camera has become common. In order to maintain focus on the subject during movie shooting, the focus lens group is constantly vibrated (wobbling) in the optical axis direction, constantly detecting changes in contrast and determining the movement direction of the focus lens group. Many methods are used. When the focus lens group is driven by wobbling, if the focus lens group is heavy, the actuator for driving the focus lens group will be large, making it difficult to reduce the size and weight of the photographing lens. Also, if the heavy focus lens group is forced to wobbling without increasing the size of the actuator, the noise generated by the actuator will become louder, and this noise will be recorded as sound during video recording, which poses a problem. . Therefore, a variable-magnification imaging optical system suitable for moving image shooting is required to reduce the weight of the focus lens group.

The optical system disclosed in Patent Document 1 has a large aperture with an F number of about 2.8 from the wide-angle end to the telephoto end, and achieves a lightweight focus lens group, but does not have a vibration reduction function. .

The optical system disclosed in Patent Document 2 has a vibration reduction function, but the F-number is dark at about 4.5 at the wide-angle end and about 5.6 at the telephoto end, and the weight of the focus lens group is reduced. is insufficient.

The optical system disclosed in Patent Document 3 has a vibration reduction function, but has a problem that the F-number is about 5.0 at the wide-angle end and about 6.3 at the telephoto end, which is dark.

The present invention has been made in view of such problems, and has a narrow half angle of view of about 5° or less at the telephoto end, a bright F number of about 2.8 to 4.0, and high optical performance throughout the zoom range. It is an object of the present invention to provide a variable-magnification imaging optical system that has a vibration reduction function and reduces the weight of a vibration reduction lens group and a focus lens group.

In order to solve the above problems, the first invention provides, in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, and a third lens group with positive refractive power. , the fourth lens group with positive refractive power, the fifth lens group consisting of one lens with negative refractive power, and the sixth lens group with positive refractive power . and, when focusing from an object at infinity to an object at close range, the fifth lens group moves along the optical axis toward the image plane, and satisfies the following conditional expression: system.
(1) 1.0<f3ew/Φm3w<1.75
(2) 1.2<f3et/Φm3t<3.0
(3) 0.7<m3ew/m3et<1.0
where f3ew: the combined focal length from the third lens group at the wide-angle end to the final lens group Φm3w: the value obtained by multiplying the paraxial marginal ray height at the top surface of the third lens group at the wide-angle end by the entrance pupil diameter f3et: at the telephoto end Composite focal length Φm3t from the third lens group to the final lens group: Value obtained by multiplying the paraxial marginal ray height at the leading surface of the third lens group at the telephoto end by the entrance pupil diameter m3ew: From the third lens group at the wide-angle end to the final lens group Combined lateral magnification up to lens group m3et: Combined lateral magnification from the third lens group at the telephoto end to the final lens group

In a second aspect of the invention, in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a positive refractive power. 4th lens group, 5th lens group with negative refracting power , and 6th lens group with positive refracting power . When zooming, the distance between the adjacent lens groups changes to move from an object at infinity to a close object. During focusing, the fifth lens group moves along the optical axis to the image plane side, and the second lens group is fixed with respect to the image plane during zooming, and is negative in order from the object side to the image side. It consists of a 2a lens group with a refractive power and a 2b lens group with a negative refractive power. A variable magnification lens system comprising a 2an lens group having a refractive power, wherein image stabilization is performed by displacing the 2b lens group in a direction perpendicular to the optical axis, and the following conditional expression is satisfied: image optical system.
(1) 1.0<f3ew/Φm3w<1.75
(2) 1.2<f3et/Φm3t<3.0
(3) 0.7<m3ew/m3et<1.0
(4) 0.0<f2b/f2a<0.3
(5) -2.0<f2ap/f2an<-1.0
where f3ew: the combined focal length from the third lens group at the wide-angle end to the final lens group Φm3w: the value obtained by multiplying the paraxial marginal ray height at the top surface of the third lens group at the wide-angle end by the entrance pupil diameter f3et: at the telephoto end Composite focal length Φm3t from the third lens group to the final lens group: Value obtained by multiplying the paraxial marginal ray height at the leading surface of the third lens group at the telephoto end by the entrance pupil diameter m3ew: From the third lens group at the wide-angle end to the final lens group Composite lateral magnification m3et up to the lens group: Composite lateral magnification f2a from the third lens group at the telephoto end to the final lens group: Focal length f2b of the 2a lens group: Focal length of the 2b lens group f2ap: Focal length of the 2b lens group Focal length f2an: Focal length of the second an lens group

According to the present invention, the half angle of view at the telephoto end is as narrow as about 5° or less, the F number is as bright as about 2.8 to 4.0, it has high optical performance throughout the zoom range, and it has a vibration reduction function. , it is possible to provide a variable magnification imaging optical system in which the weights of the anti-vibration lens group and the focus lens group are suppressed.

It is a lens configuration diagram according to Example 1 of the imaging optical system of the present invention. 4 is a longitudinal aberration diagram of the imaging optical system of Example 1 at the wide-angle end during focusing at infinity. FIG. FIG. 10 is a longitudinal aberration diagram of the imaging optical system of Example 1 at an intermediate focal length at the time of focusing at infinity; 4 is a longitudinal aberration diagram of the imaging optical system of Example 1 at the telephoto end at the time of focusing at infinity. FIG. 4 is a lateral aberration diagram at the wide-angle end of the imaging optical system of Example 1 at the time of focusing at infinity; FIG. FIG. 4 is a lateral aberration diagram of the imaging optical system of Example 1 at an intermediate focal length at the time of focusing at infinity; 4 is a lateral aberration diagram of the imaging optical system of Example 1 at the telephoto end at the time of focusing at infinity; FIG. FIG. 10 is a lateral aberration diagram at the wide-angle end of the imaging optical system of Example 1 at the time of 0.4° image stabilization during focusing at infinity; FIG. 10 is a lateral aberration diagram of the image forming optical system of Example 1 at the time of 0.4° image stabilization during focusing at an intermediate focal length to infinity; FIG. 10 is a lateral aberration diagram of the imaging optical system of Example 1 at the telephoto end at the time of focusing at infinity and with 0.4° image stabilization; It is a lens block diagram concerning Example 2 of the imaging optical system of this invention. FIG. 11 is a longitudinal aberration diagram of the imaging optical system of Example 2 at the wide-angle end during focusing at infinity. FIG. 10 is a longitudinal aberration diagram of the imaging optical system of Example 2 at an intermediate focal length at the time of infinity focusing; FIG. 10 is a longitudinal aberration diagram of the imaging optical system of Example 2 at the telephoto end at the time of focusing at infinity; FIG. 11 is a lateral aberration diagram at the wide-angle end of the imaging optical system of Example 2 at the time of focusing at infinity; FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 2 at an intermediate focal length at the time of focusing at infinity; FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 2 at the telephoto end at the time of focusing at infinity; FIG. 11 is a lateral aberration diagram at the wide-angle end of the imaging optical system of Example 2 at the time of 0.4° image stabilization during focusing at infinity; FIG. 10 is a lateral aberration diagram at the time of 0.4° image stabilization at the time of infinity focusing at an intermediate focal length of the imaging optical system of Example 2; FIG. 11 is a lateral aberration diagram at the telephoto end of the imaging optical system of Example 2 at the time of 0.4° image stabilization during focusing at infinity; It is a lens block diagram concerning Example 3 of the imaging optical system of this invention. FIG. 10 is a longitudinal aberration diagram of the imaging optical system of Example 3 at the wide-angle end during focusing at infinity. FIG. 11 is a longitudinal aberration diagram of the imaging optical system of Example 3 at an intermediate focal length at the time of focusing at infinity; FIG. 11 is a longitudinal aberration diagram of the imaging optical system of Example 3 at the telephoto end at the time of focusing at infinity; FIG. 11 is a lateral aberration diagram at the wide-angle end of the imaging optical system of Example 3 at the time of focusing at infinity; FIG. 10 is a lateral aberration diagram of the imaging optical system of Example 3 at the intermediate focal length at the time of focusing at infinity; FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 3 at the telephoto end at the time of focusing at infinity; FIG. 10 is a lateral aberration diagram at the wide-angle end of the imaging optical system of Example 3 at the time of 0.4° image stabilization during focusing at infinity; FIG. 11 is a lateral aberration diagram at the time of 0.4° vibration reduction at the time of infinity focusing at an intermediate focal length of the imaging optical system of Example 3; FIG. 11 is a lateral aberration diagram at the telephoto end of the imaging optical system of Example 3 at the time of 0.4° image stabilization during focusing at infinity; It is a lens block diagram concerning Example 4 of the imaging optical system of this invention. FIG. 12 is a longitudinal aberration diagram of the imaging optical system of Example 4 at the wide-angle end during focusing at infinity. FIG. 11 is a longitudinal aberration diagram of the imaging optical system of Example 4 at the intermediate focal length at the time of focusing at infinity. FIG. 11 is a longitudinal aberration diagram of the imaging optical system of Example 4 at the telephoto end at the time of focusing at infinity. FIG. 11 is a lateral aberration diagram at the wide-angle end of the imaging optical system of Example 4 at the time of infinity focusing; FIG. 12 is a lateral aberration diagram of the imaging optical system of Example 4 at the intermediate focal length at the time of focusing at infinity; FIG. 11 is a lateral aberration diagram at the telephoto end of the imaging optical system of Example 4 at the time of focusing at infinity; FIG. 11 is a lateral aberration diagram at the wide-angle end of the imaging optical system of Example 4 at the time of 0.4° image stabilization during focusing at infinity; FIG. 11 is a lateral aberration diagram at the time of 0.4° image stabilization at the time of infinity focusing at an intermediate focal length of the imaging optical system of Example 4; FIG. 11 is a lateral aberration diagram at the telephoto end of the imaging optical system of Example 4 at the time of 0.4° image stabilization during focusing at infinity; It is a lens block diagram concerning Example 5 of the imaging optical system of this invention. FIG. 12 is a longitudinal aberration diagram of the imaging optical system of Example 5 at the wide-angle end during focusing at infinity. FIG. 12 is a longitudinal aberration diagram of the imaging optical system of Example 5 at the intermediate focal length at the time of focusing at infinity. FIG. 11 is a longitudinal aberration diagram of the imaging optical system of Example 5 at the telephoto end during focusing at infinity. FIG. 11 is a lateral aberration diagram at the wide-angle end of the imaging optical system of Example 5 at the time of focusing at infinity; FIG. 12 is a lateral aberration diagram of the imaging optical system of Example 5 at the intermediate focal length at the time of focusing at infinity; FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 5 at the telephoto end at the time of focusing at infinity; FIG. 12 is a lateral aberration diagram at the wide-angle end of the imaging optical system of Example 5 at the time of 0.4° image stabilization during focusing at infinity; FIG. 12 is a lateral aberration diagram of the image forming optical system of Example 5 at the time of 0.4° image stabilization during focusing at infinity at an intermediate focal length; FIG. 12 is a lateral aberration diagram at the telephoto end of the imaging optical system of Example 5 at the time of 0.4° image stabilization during focusing at infinity;

1, 11, 21, 31, and 41, the variable power imaging optical system according to the present invention has positive refraction lenses in order from the object side to the image side, as shown in the lens configuration diagrams of the respective embodiments of FIGS. Power first lens group, negative refractive power second lens group, positive refractive power third lens group, positive refractive power fourth lens group, negative refractive power fifth lens group, positive refractive power During zooming, the distance between adjacent lens groups changes, and when focusing from an object at infinity to a close object, the fifth lens group moves along the optical axis toward the image plane. Moving.

The first lens group with positive refractive power and the second lens group with negative refractive power increase the distance between them when zooming from the wide-angle end to the telephoto end. It's working.

In addition, since light rays are converged by the first lens group having a positive refractive power, the height of light rays incident on the second lens group is lowered. is preferably arranged in the second lens group.

The third lens group with positive refractive power and the fourth lens group with positive refractive power move toward the object side during zooming from the wide-angle end to the telephoto end, thereby compensating for the image plane and enhancing the zooming effect. is also responsible for some of the

The third lens group with positive refracting power converges the light flux diverged by the second lens group with negative refracting power and emits it as a nearly afocal light flux. It converges the light beams emitted from the three lens groups.

Since the luminous flux in the section between the third lens group and the fourth lens group is close to afocal, even if the distance between the third lens group and the fourth lens group is changed, there is not much change in the passage of the axial luminous flux. Aberration fluctuations are small, but astigmatism fluctuates because off-axis light beam passage changes. Using this property, it is possible to satisfactorily correct astigmatism over the entire zoom range by appropriately setting the distance between the third lens group and the fourth lens group during zooming.

A light flux converged by the fourth lens group of positive refractive power arranged on the object side enters the fifth lens group of negative refractive power. Weight reduction is possible.

The sixth lens group is arranged in the middle of the convergence of the light beam toward the image plane, and by changing the distance from the fifth lens group, the height of the incident F-number light beam is changed to change the spherical aberration and It is possible to change axial chromatic aberration. Using this property, it is possible to satisfactorily correct spherical aberration and longitudinal chromatic aberration over the entire zoom range by appropriately setting the distance between the fifth lens group and the sixth lens group during zooming.

Further, the variable-magnification imaging optical system according to the present invention is characterized by satisfying the following conditional expressions.
(1) 1.0<f3ew/Φm3w<1.75
(2) 1.2<f3et/Φm3t<3.0
(3) 0.7<m3ew/m3et<1.0
where f3ew: the combined focal length from the third lens group at the wide-angle end to the final lens group Φm3w: the value obtained by multiplying the paraxial marginal ray height at the top surface of the third lens group at the wide-angle end by the entrance pupil diameter f3et: at the telephoto end Composite focal length Φm3t from the third lens group to the final lens group: Value obtained by multiplying the paraxial marginal ray height at the leading surface of the third lens group at the telephoto end by the entrance pupil diameter m3ew: From the third lens group at the wide-angle end to the final lens group Combined lateral magnification up to lens group m3et: Combined lateral magnification from the third lens group at the telephoto end to the final lens group

Conditional expression (1) secures a large aperture F number of 2.8 at the wide-angle end and ensures optical performance at the wide-angle end. , defines a preferable range for the ratio of the value obtained by multiplying the height of the paraxial marginal ray at the front surface of the third lens group at the wide-angle end by the diameter of the entrance pupil.

If the positive refractive power of the composite system from the third lens group at the wide-angle end to the final lens group weakens beyond the upper limit of conditional expression (1), the distance between the conjugates from the third lens group to the final lens group increases. Since it is long, it becomes difficult to make the overall length of the wide-angle end compact. Also, if the value obtained by multiplying the height of the paraxial marginal ray on the front surface of the third lens group at the wide-angle end by the diameter of the entrance pupil becomes small, it becomes difficult to increase the aperture at the wide-angle end.

On the other hand, if the lower limit of conditional expression (1) is exceeded, the positive refractive power of the composite system from the third lens group at the wide-angle end to the final lens group becomes strong, or the leading surface of the third lens group at the wide-angle end becomes As the value obtained by multiplying the height of the paraxial marginal ray by the diameter of the entrance pupil increases, the apparent F-number from the third lens group to the final lens group at the wide-angle end decreases. becomes difficult.

By limiting the lower limit to 1.1 or the upper limit to 1.5 for conditional expression (1), the above effect can be more reliably achieved.

In order to secure a large aperture F number of 4.0 at the telephoto end and to secure optical performance at the telephoto end, conditional expression (2) requires a synthetic focal point from the third lens group to the final lens group at the telephoto end. It defines a preferable range for the distance and the ratio of the value obtained by multiplying the height of the paraxial marginal ray at the front surface of the third lens group at the telephoto end by the diameter of the entrance pupil.

When the upper limit of conditional expression (2) is exceeded and the positive refractive power of the composite system from the third lens group to the final lens group at the telephoto end becomes weak, Since the distance between conjugates is longer, the overall length at the wide-angle end is longer, and the amount of change in the overall length from the wide-angle end to the telephoto end is greater due to the greater movement of the third and subsequent lenses due to zooming, resulting in less eccentricity. It becomes difficult to create a highly flexible mechanical structure. In addition, when trying to construct a mechanical structure with a small amount of eccentricity, a structure is provided in the outer diameter direction, which makes it difficult to make the whole compact. Also, if the value obtained by multiplying the paraxial marginal ray height at the front surface of the third lens group at the telephoto end by the diameter of the entrance pupil becomes small, the F-number at the telephoto end increases, making it difficult to obtain the desired F-number. .

On the other hand, if the lower limit of conditional expression (2) is exceeded, the positive refractive power of the composite system from the third lens group at the telephoto end to the final lens group becomes strong, or the leading surface of the third lens group at the telephoto end becomes As the value obtained by multiplying the paraxial marginal ray height by the entrance pupil diameter increases, the apparent F-number from the third lens group to the final lens group at the telephoto end decreases. Astigmatism correction becomes difficult.

By limiting the lower limit to 1.4 or the upper limit to 2.5 for conditional expression (2), the above effect can be more reliably achieved.

In order to share the zoom ratio of the third and subsequent lens groups and to suppress changes in the F-number during zooming, conditional expression (3) determines the combined lateral magnification from the third lens group at the wide-angle end to the final lens group. , defines a preferable range for the ratio of the combined lateral magnification from the third lens group at the telephoto end to the final lens group.

When the upper limit of conditional expression (3) is exceeded and the load of zooming in the third and subsequent lens groups is almost eliminated during zooming, the zooming in the second lens group must be increased in order to obtain a desired zoom ratio. First, it becomes difficult to correct aberration fluctuations, especially distortion aberration fluctuations, in the second lens group. Further, when the combined lateral magnification from the third lens group to the final lens group at the wide-angle end increases, the distance between conjugates of the combined system increases, and the total length at the wide-angle end cannot be made compact. Furthermore, in order to make the total length compact, the refractive power of the composite system must be strengthened, and aberration correction becomes difficult, making it impossible to increase the aperture at the wide-angle end.

On the other hand, if the composite lateral magnification from the third lens group to the final lens group at the wide-angle end becomes smaller than the lower limit of conditional expression (3), it becomes difficult to secure the back focus at the wide-angle end. Furthermore, if an attempt is made to secure the back focus in this state, the focal length of the third and subsequent lens groups at the wide-angle end must be increased, making it difficult to increase the aperture at the wide-angle end. Also, when the combined lateral magnification from the third lens group at the telephoto end to the final lens group increases, it becomes difficult to secure the space between the second lens group and the second lens group at the telephoto end. The combined focal length from the lens group to the final lens group must be lengthened, which increases the amount of movement of each lens group during zooming and complicates the mechanical structure.

By limiting the lower limit of conditional expression (3) to 0.75 or the upper limit to 0.98, the above effects can be more reliably achieved.

The second lens group of the variable power imaging optical system according to the present invention is composed of, in order from the object side to the image side, the 2a lens group with negative refractive power and the 2b lens group with negative refractive power. Vibration reduction is performed by displacing the 2b lens group in the direction perpendicular to the optical axis. By constructing a telephoto type with the first lens group of positive refractive power and the 2a lens group of negative refractive power, it is possible to shorten the total length of the combined system of the first lens group and the 2a lens group, Further, by using the 2b lens group, in which the height of incident light rays is lower, as the anti-vibration lens group, the weight of the anti-vibration lens group can be further reduced. Furthermore, by combining the 2a lens group with negative refractive power with the 2ap lens group with positive refractive power and the 2an lens group with negative refractive power, it is possible to correct coma and astigmatism on the telephoto side. becomes. From these, it is desirable that the second lens group satisfy the following conditional expressions.
(4) 0.0<f2b/f2a<0.3
(5) -2.0<f2ap/f2an<-1.0
where f2a: focal length of the 2a lens group f2b: focal length of the 2b lens group f2ap: focal length of the 2ap lens group f2an: focal length of the 2an lens group

Conditional expression (4) defines the relationship between the focal lengths of the 2a lens group and the 2b lens group. , show favorable conditions for correcting coma and astigmatism over the entire zoom range.

If the upper limit of conditional expression (4) is exceeded and the negative refractive power of the 2a lens group becomes relatively strong, it becomes difficult to correct excessive spherical aberration on the telephoto side. In addition, the coma flare of the lower ray on the telephoto side becomes under, which is not preferable.
In addition, since the meridional image plane also shifts in the negative direction, in order to correct it with the rear lens group, a component of the meridional image plane in the positive direction must be forcibly generated, and astigmatism is corrected over the entire zoom range. becomes difficult. Furthermore, the negative refractive power of the 2a-th lens group increases the tendency of the luminous flux to diverge, so that the height of the rays incident on the 2b-th lens group, which is the anti-vibration group, increases, making it difficult to reduce the weight of the anti-vibration group.

If the lower limit of conditional expression (4) is exceeded and the negative refractive power of the 2a lens group is relatively weakened, it becomes difficult to correct under-correction of spherical aberration on the telephoto side. In addition, it becomes difficult to correct coma flare of the lower ray on the telephoto side and excessive meridional astigmatism.

By limiting the lower limit to 0.03 or the upper limit to 0.2 for conditional expression (4), the above effects can be more reliably achieved.

In order to shorten the total length of the combined system of the 1st lens group and the 2a lens group, and to correct coma and astigmatism on the telephoto side, conditional expression (5) is satisfied. This defines a preferable range for the focal length relationship of the 2an lens group.

When the upper limit of conditional expression (5) is exceeded and the positive refractive power of the 2ap lens group becomes strong or the negative refractive power of the 2an lens group becomes weak, the negative refractive power of the entire 2a lens group becomes weak, The telephoto type is weakened in the synthetic system of the first lens group and the 2a lens group, and it becomes difficult to reduce the total length on the wide-angle side by shortening the synthetic system of the first lens group and the 2a lens group. In addition, it is difficult to correct under-correction of spherical aberration on the telephoto side, which is not preferable.

If the lower limit of conditional expression (5) is exceeded and the positive refractive power of the 2ap lens group becomes weaker or the negative refractive power of the 2an lens group becomes stronger, the negative refractive power of the entire 2a lens group becomes stronger, It becomes difficult to correct excessive spherical aberration on the telephoto side. In addition, the coma flare of the lower ray on the telephoto side becomes under, which is not preferable.

By restricting the lower limit to -1.7 or the upper limit to -1.25 for conditional expression (5), the above effects can be more reliably achieved.

Further, in the variable-magnification imaging optical system according to the present invention, it is desirable that the fifth lens group consist of one negative lens.

By constructing the fifth lens group, which is the focus lens group, from a single negative lens, it becomes possible to further reduce the weight of the focus lens group. It becomes possible to provide an image optical system.

Next, the lens configuration of each embodiment of the variable-magnification imaging optical system according to the present invention will be described. In the following description, lens configurations are described in order from the object side to the image side. Ln is a symbol indicating a lens corresponding to the lens number n when the lenses are counted in order from the object side.

FIG. 1 is a lens configuration diagram of an imaging optical system according to Example 1 of the present invention.

In order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a negative and a sixth lens group G6 with a positive refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, and the second lens The group G2 is fixed, the third lens group G3 moves to the object side, the fourth lens group G4 moves to the object side, the fifth lens group G5 moves to the object side, and the sixth lens group G6 moves. It is configured. Also, when focusing from an infinite distance object to a close distance object, the fifth lens group G5 moves along the optical axis toward the image plane side.

The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 having a convex surface facing the object side.

The second lens group G2 is composed of, in order from the object side, a 2a lens group G2a with negative refractive power and a 2b lens group G2b with negative refractive power. Vibration isolation is performed by displacement. The 2a-th lens group G2a is composed of a convex meniscus lens L4 having a convex surface facing the object side, which is the 2ap lens group, and a cemented lens composed of a biconvex lens L5 and a biconcave lens L6, which is the 2an lens group. The 2b-th lens group G2b is composed of a biconcave lens L7 and a cemented lens composed of a biconcave lens L8 and a biconvex lens L9.

An aperture stop is provided on the object side of the third lens group G3, and moves together with the third lens group G3 as the magnification changes.

The third lens group G3 includes a biconvex lens L10, a biconvex lens L11, a cemented lens composed of a biconvex lens L12 and a biconcave lens L13, a biconvex lens L14, and a biconcave lens L15.

The fourth lens group G4 is composed of a cemented lens composed of a negative meniscus lens L16 having a convex surface facing the object side and a biconvex lens L17, and a positive meniscus lens L18 having a convex surface facing the object side.

The fifth lens group G5 is composed of a negative meniscus lens L19 having a convex surface facing the object side.

The sixth lens group G6 is composed of a cemented lens composed of a biconcave lens L20 and a biconvex lens L21.

FIG. 11 is a lens configuration diagram of an imaging optical system according to Example 2 of the present invention.

In order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a negative and a sixth lens group G6 with a positive refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, and the second lens The group G2 is fixed, the third lens group G3 moves to the object side, the fourth lens group G4 moves to the object side, the fifth lens group G5 moves to the object side, and the sixth lens group G6 moves to the object side. It is configured to move to Also, when focusing from an infinite distance object to a close distance object, the fifth lens group G5 moves along the optical axis toward the image plane side.

The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a biconvex lens L3.

The second lens group G2 is composed of, in order from the object side, a 2a lens group G2a with negative refractive power and a 2b lens group G2b with negative refractive power. Vibration isolation is performed by displacement. The 2a-th lens group G2a is composed of a positive meniscus lens L4 having a convex surface facing the object side, which is the 2ap lens group, and a cemented lens composed of a biconvex lens L5 and a biconcave lens L6, which is the 2an lens group. The 2b-th lens group G2b is composed of a biconcave lens L7 and a cemented lens composed of a biconcave lens L8 and a biconvex lens L9.

An aperture stop is provided on the object side of the third lens group G3, and moves together with the third lens group G3 as the magnification changes.

The third lens group G3 includes a biconvex lens L10, a biconvex lens L11, a cemented lens composed of a biconvex lens L12 and a biconcave lens L13, a biconvex lens L14, and a biconcave lens L15.

The fourth lens group G4 is composed of a cemented lens composed of a negative meniscus lens L16 having a convex surface facing the object side and a biconvex lens L17, and a positive meniscus lens L18 having a convex surface facing the object side.

The fifth lens group G5 is composed of a negative meniscus lens L19 having a convex surface facing the object side.

The sixth lens group G6 is composed of a cemented lens composed of a biconcave lens L20 and a biconvex lens L21.

FIG. 21 is a lens configuration diagram of an imaging optical system according to Example 3 of the present invention.

In order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a negative and a sixth lens group G6 with a positive refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, and the second lens The group G2 is fixed, the third lens group G3 moves to the object side, the fourth lens group G4 moves to the object side, the fifth lens group G5 moves to the object side, and the sixth lens group G6 moves to the object side. It is configured to move to Also, when focusing from an object at infinity to an object at close range, the fifth lens group G5 moves along the optical axis toward the image plane.

The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 having a convex surface facing the object side.

The second lens group G2 is composed of, in order from the object side, a 2a lens group G2a with negative refractive power and a 2b lens group G2b with negative refractive power. Vibration isolation is performed by displacement. The 2a-th lens group G2a is composed of a biconvex lens L4 as the 2ap lens group and a cemented lens composed of a biconvex lens L5 and a biconcave lens L6 as the 2an lens group. The 2b-th lens group G2b is composed of a biconcave lens L7 and a cemented lens composed of a biconcave lens L8 and a biconvex lens L9.

An aperture stop is provided on the object side of the third lens group G3, and moves together with the third lens group G3 as the magnification changes.

The third lens group G3 consists of a positive meniscus lens L10 having a concave surface facing the object side, a biconvex lens L11, a cemented lens composed of a biconvex lens L12 and a biconcave lens L13, and a cemented lens composed of a biconvex lens L14 and a biconcave lens L15. Configured.

The fourth lens group G4 is composed of a cemented lens composed of a negative meniscus lens L16 having a convex surface facing the object side and a biconvex lens L17, and a positive meniscus lens L18 having a convex surface facing the object side.

The fifth lens group G5 is composed of a negative meniscus lens L19 having a convex surface facing the object side.

The sixth lens group G6 is composed of a cemented lens composed of a biconcave lens L20 and a biconvex lens L21.

FIG. 31 is a lens configuration diagram of an imaging optical system according to Example 4 of the present invention.

In order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a negative and a sixth lens group G6 with a positive refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, and the second lens The group G2 is fixed, the third lens group G3 moves to the object side, the fourth lens group G4 moves to the object side, the fifth lens group G5 moves to the object side, and the sixth lens group G6 moves. It is configured. Also, when focusing from an object at infinity to an object at close range, the fifth lens group G5 moves along the optical axis toward the image plane.

The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 having a convex surface facing the object side.

The second lens group G2 is composed of, in order from the object side, a 2a lens group G2a with negative refractive power and a 2b lens group G2b with negative refractive power. Vibration isolation is performed by displacement. The 2a-th lens group G2a is composed of a biconvex lens L4 as the 2ap lens group and a biconcave lens L5 as the 2an lens group. The 2b-th lens group G2b is composed of a biconcave lens L6, a cemented lens composed of a biconcave lens L7 and a convex meniscus L8 having a convex surface facing the object side.

An aperture stop is provided on the object side of the third lens group G3, and moves together with the third lens group G3 as the magnification changes.

The third lens group G3 is composed of a biconvex lens L9, a positive meniscus lens L10 having a convex surface facing the object side, a cemented lens composed of a biconvex lens L11 and a biconcave lens L12, a biconvex lens L13, and a biconcave lens L14. be.

The fourth lens group G4 is composed of a cemented lens composed of a negative meniscus lens L15 having a convex surface facing the object side and a biconvex lens L16, and a biconvex lens L17.

The fifth lens group G5 is composed of a negative meniscus lens L18 having a convex surface facing the object side.

The sixth lens group G6 is composed of a cemented lens composed of a biconcave lens L19 and a biconvex lens L20.

FIG. 41 is a lens configuration diagram of an imaging optical system according to Example 5 of the present invention.

In order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a negative and a sixth lens group G6 with a positive refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, and the second lens The group G2 is fixed, the third lens group G3 moves to the object side, the fourth lens group G4 moves to the object side, the fifth lens group G5 moves to the object side, and the sixth lens group G6 moves. It is configured. Also, when focusing from an infinite distance object to a close distance object, the fifth lens group G5 moves along the optical axis toward the image plane side.

The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 having a convex surface facing the object side.

The second lens group G2 is composed of, in order from the object side, a 2a lens group G2a with negative refractive power and a 2b lens group G2b with negative refractive power. Vibration isolation is performed by displacement. The 2a-th lens group G2a is composed of a biconvex lens L4 as the 2ap lens group and a biconcave lens L5 as the 2an lens group. The 2b-th lens group G2b is composed of a cemented lens composed of a positive meniscus lens L6 having a concave surface facing the object side and a double concave lens L7, and a double concave lens L8.

An aperture stop is provided on the object side of the third lens group G3, and moves together with the third lens group G3 as the magnification changes.

The third lens group G3 is composed of a biconvex lens L9, a positive meniscus lens L10 having a convex surface facing the object side, a cemented lens composed of a biconvex lens L11 and a biconcave lens L12, a biconvex lens L13, and a biconcave lens L14. be.

The fourth lens group G4 is composed of a cemented lens composed of a negative meniscus lens L15 having a convex surface facing the object side and a biconvex lens L16, and a positive meniscus lens L17 having a convex surface facing the object side.

The fifth lens group G5 is composed of a negative meniscus lens L18 having a convex surface facing the object side.

The sixth lens group G6 is composed of a cemented lens composed of a negative meniscus lens L19 having a concave surface facing the object side and a positive meniscus lens L20 having a concave surface facing the object side.

Numerical examples and values corresponding to conditional expressions for each example of the variable-magnification imaging optical system according to the present invention will now be described.

In [Surface data], the surface number is the number of the lens surface or aperture stop counted in order from the object side, r is the radius of curvature of the lens surface, d is the distance between the lens surfaces, and nd is for the d-line (wavelength 587.56 nm). The refractive index νd indicates the Abbe number for the d-line (wavelength 587.56 nm).

[Various data] shows values such as the zoom ratio and the focal length in each focal length state.

[Variable Spacing Data] shows the variable spacing and BF values in each focal length state.

In [Lens group data], the surface number of the lens surface closest to the object side constituting each lens group and the focal length of the entire lens group are shown.

In each aberration diagram corresponding to each embodiment, d, g, and C represent the d-line, g-line, and C-line, respectively, and ΔS, ΔM represent the sagittal image plane and meridional image plane, respectively.

In addition, in the values of all the specifications below, unless otherwise specified, millimeters (mm) are used for the focal length f, radius of curvature r, distance between lens surfaces d, and other lengths. The system is not limited to this because the same optical performance can be obtained in both proportional enlargement and proportional reduction.

Numerical example 1
Unit: mm
[Surface data]
Face number rd nd vd
Object ∞ ∞
1 175.0608 1.5000 1.83481 42.72
2 67.6322 10.3819 1.49700 81.61
3 -345.7799 0.1500
4 63.6048 8.6443 1.49700 81.61
5 2693.2686 (d5)
6 51.8382 3.7610 1.92119 23.96
7 698.2131 1.7410
8 217.1395 2.7165 1.48749 70.44
9 -102.2843 0.7500 1.68893 31.16
10 33.4698 6.1117
11 -111.5071 0.7500 1.77250 49.62
12 36.8675 2.5235
13 -34.4544 0.7500 1.77250 49.62
14 35.2741 2.8149 1.92119 23.96
15 -1025.3607 (d15)
16 (Aperture) ∞ 1.0000
17 90.5472 3.1983 1.83500 42.98
18 -70.2172 0.1500
19 71.4539 2.6286 1.49700 81.61
20 -351.2698 0.2000
21 49.3426 4.7238 1.49700 81.61
22 -32.8446 0.7500 1.92119 23.96
23 90.3183 0.1500
24 21.1493 5.4496 1.80518 25.46
25 -67.9363 0.1975
26 -69.6747 0.7500 1.90366 31.31
27 22.6080 (d27)
28 109.9734 0.7500 1.90366 31.31
29 21.3010 5.1829 1.51742 52.15
30 -32.5309 0.3000
31 30.9092 2.9405 1.88100 40.14
32 517.6317 (d32)
33 133.2448 0.7500 1.91082 35.25
34 24.1009 (d34)
35 -47.5493 0.7500 1.65100 56.15
36 307.2099 3.2603 1.92119 23.96
37 -41.6139 (d37)
38 ∞ 4.2000 1.51680 64.20
39∞ (BF)

[Various data]
Zoom ratio 3.90
Wide Angle Medium Telephoto Focal Length 50.01 95.01 195.01
F number 2.92 3.21 4.03
Full angle of view 2ω 24.01 12.68 6.22
Image height Y 10.82 10.82 10.82
Overall lens length 150.01 178.18 194.99

[Variable interval data]
wide-angle medium-telephoto
d0 ∞ ∞ ∞
d5 3.0000 31.3043 47.9855
d15 18.8812 14.8447 4.3814
d27 8.1592 2.8386 4.4336
d32 7.0393 3.0549 1.5000
d34 7.6757 12.6673 31.4573
d37 0.1500 8.3948 0.1500
BF 25.1796 25.1517 25.1588

[Lens group data]
Group Starting surface Focal length
G1 1 113.05
G2 6 -22.92
G3 16 39.85
G4 28 29.25
G5 33-32.41
G6 35 100.51
G2a 6 -624.45
G2b 11 -21.58
G2ap 6 60.62
G2an 8 -49.47

Numerical example 2
Unit: mm
[Surface data]
Face number rd nd vd
Object ∞ ∞
1 170.8321 1.5000 1.83481 42.72
2 72.2282 9.7711 1.49700 81.61
3 -363.4221 0.1500
4 70.4135 8.2954 1.49700 81.61
5-8802.0677 (d5)
6 53.4125 3.5909 1.92119 23.96
7 622.5082 1.8307
8 196.0097 2.7275 1.49700 81.61
9 -99.6700 0.7500 1.80000 29.84
10 37.5360 6.5260
11 -174.7786 0.7500 1.77250 49.62
12 37.5090 2.7692
13 -29.1619 0.7500 1.80420 46.50
14 34.8003 3.0953 1.92119 23.96
15 -218.6935 (d15)
16 (Aperture) ∞ 1.0000
17 144.5443 3.3756 1.88300 40.80
18 -57.8209 0.1500
19 78.0504 2.8228 1.49700 81.61
20 -227.6197 0.2000
21 47.3799 5.4033 1.49700 81.61
22 -31.4516 0.7500 1.92119 23.96
23 101.3495 0.1500
24 22.6667 5.4845 1.80518 25.46
25 -118.9559 0.1500
26 -143.2865 0.7500 1.88300 40.80
27 24.7297 (d27)
28 98.7131 0.7500 1.92119 23.96
29 20.7277 5.8938 1.54072 47.20
30 -34.3823 0.3000
31 33.5304 2.9328 1.88300 40.80
32 323.4842 (d32)
33 69.7672 0.7500 1.90366 31.31
34 23.0909 (d34)
35 -70.5879 0.7500 1.77250 49.62
36 28.2227 3.3420 1.92119 23.96
37 -144.5960 (d37)
38 ∞ 4.2000 1.51680 64.20
39∞ (BF)

[Various data]
Zoom ratio 3.90
Wide Angle Medium Telephoto Focal Length 50.00 97.08 195.00
F number 2.92 3.32 4.02
Full angle of view 2ω 24.22 12.44 6.23
Image height Y 10.82 10.82 10.82
Overall lens length 150.00 178.39 195.00

[Variable interval data]
wide-angle medium-telephoto
d0 ∞ ∞ ∞
d5 3.0000 31.4884 48.0679
d15 18.2220 13.4499 4.3497
d27 10.4351 6.5840 4.5354
d32 6.7166 3.8842 1.5000
d34 7.7533 10.1731 17.9035
d37 0.1500 9.0908 14.9234
BF 22.0622 22.0597 22.0592

[Lens group data]
Group Starting surface Focal length
G1 1 115.48
G2 6 -21.55
G3 16 35.45
G4 28 31.57
G5 33-38.49
G6 35 1231.65
G2a 6 -268.58
G2b 11 -21.76
G2ap 6 63.23
G2an 8 -46.06

Numerical example 3
Unit: mm
[Surface data]
Face number rd nd vd
Object ∞ ∞
1 156.2876 1.5000 1.83481 42.72
2 70.4862 11.0681 1.49700 81.61
3 -340.8497 0.1500
4 64.8418 9.2597 1.49700 81.61
5 1278.2068 (d5)
6 91.0918 2.8901 1.92119 23.96
7-921.0846 2.0626
8 159.0477 3.1482 1.49700 81.61
9 -65.3948 0.7500 1.91082 35.25
10 57.6161 6.3173
11 -206.4653 0.7500 1.77250 49.62
12 37.1115 2.6659
13 -28.7405 0.7500 1.77250 49.62
14 32.3569 2.9723 1.92119 23.96
15 -525.5198 (d15)
16 (Aperture) ∞ 1.0000
17 -1266.0495 3.1570 1.88300 40.80
18 -42.3726 0.1500
19 84.9607 2.5330 1.49700 81.61
20 -359.6400 0.2000
21 50.7204 5.2080 1.49700 81.61
22 -30.1696 0.7500 1.92119 23.96
23 298.2153 0.1500
24 22.9286 4.9950 1.84666 23.78
25 -250.2516 0.7500 1.88300 40.80
26 25.0632 (d26)
27 73.2791 0.7500 1.92119 23.96
28 21.3575 5.7191 1.49700 81.61
29 -33.2178 0.3000
30 39.4951 2.7275 1.88300 40.80
31 554.8483 (d31)
32 81.2377 0.7500 1.90366 31.31
33 23.1489 (d33)
34 -85.6085 0.7500 1.77250 49.62
35 26.8143 3.4243 1.92119 23.96
36 -145.4924 (d36)
37 ∞ 4.2000 1.51680 64.20
38∞ (BF)

[Various data]
Zoom ratio 3.90
Wide Angle Medium Telephoto Focal Length 49.98 98.35 194.85
F number 2.92 3.34 4.02
Full angle of view 2ω 24.27 12.28 6.23
Image height Y 10.82 10.82 10.82
Total lens length 149.99 181.49 194.96

[Variable interval data]
wide-angle medium-telephoto
d0 ∞ ∞ ∞
d5 3.0000 34.6302 48.0829
d15 15.6411 13.9851 4.9654
d26 10.2504 5.9042 4.3441
d31 8.1267 3.5145 1.5000
d33 7.5360 9.9683 16.8613
d36 0.1500 8.2044 13.9503
BF 23.4842 23.4834 23.4541

[Lens group data]
Group Starting surface Focal length
G1 1 108.11
G2 6 -19.32
G3 16 33.82
G4 27 34.06
G5 32 -36.05
G6 34 340.44
G2a 6 -154.27
G2b 11 -21.63
G2ap 6 90.11
G2an 8 -52.95

Numerical example 4
Unit: mm
[Surface data]
Face number rd nd vd
Object ∞ ∞
1 160.8708 1.5000 1.83481 42.72
2 64.7058 10.9601 1.49700 81.61
3 -336.2682 0.1500
4 60.5683 9.2800 1.49700 81.61
5 2075.8099 (d5)
6 95.8105 2.8769 1.92119 23.96
7 -366.5220 2.9777
8 -157.0296 0.7500 1.74951 35.33
9 48.4575 5.8562
10 -78.8084 0.7500 1.77250 49.62
11 42.7001 2.2147
12 -46.7764 0.7500 1.58913 61.25
13 35.6609 2.6206 1.92119 23.96
14 184.2449 (d14)
15 (Aperture) ∞ 1.0000
16 113.3109 3.1490 1.88300 40.80
17 -68.9041 0.1500
18 56.5003 2.6599 1.49700 81.61
19 751.6839 0.2000
20 36.9038 5.1151 1.49700 81.61
21 -35.5606 0.7500 1.92119 23.96
22 50.0968 0.1500
23 22.7432 4.8896 1.80518 25.46
24 -107.2821 1.1420
25 -102.0568 0.7500 1.88300 40.80
26 25.4528 (d26)
27 107.0196 0.7500 1.90366 31.31
28 22.9962 5.5151 1.43700 95.10
29 -29.3676 0.3000
30 31.7397 3.3005 1.88300 40.76
31 -416.7577 (d31)
32 160.2363 0.7500 1.88300 40.80
33 23.5801 (d33)
34 -57.0381 0.7500 1.80420 46.50
35 4133.9669 3.1883 1.92119 23.96
36 -39.3686 (d36)
37 ∞ 4.2000 1.51680 64.20
38∞ (BF)

[Various data]
Zoom ratio 3.90
Wide Angle Medium Telephoto Focal Length 49.97 95.16 194.85
F number 2.92 3.15 4.02
Full angle of view 2ω 24.05 12.64 6.23
Image height Y 10.82 10.82 10.82
Overall lens length 149.96 180.25 194.96

[Variable interval data]
wide-angle medium-telephoto
d0 ∞ ∞ ∞
d5 3.0000 33.4287 47.9964
d14 17.6543 16.1149 4.7430
d26 8.2989 2.5666 4.1566
d31 8.4255 3.1945 1.5000
d33 7.5930 12.7436 31.5775
d36 0.1500 7.3839 0.1500
BF 25.4406 25.4180 25.4380

[Lens group data]
Group Starting surface Focal length
G1 1 106.29
G2 6 -22.83
G3 15 40.98
G4 27 28.77
G5 32 -31.39
G6 34 99.88
G2a 6 -141.28
G2b 10 -27.08
G2ap 6 82.70
G2an 8 -49.33

Numerical example 5
Unit: mm
[Surface data]
Face number rd nd vd
Object ∞ ∞
1 167.2270 1.5000 1.83481 42.72
2 65.9869 10.4724 1.49700 81.61
3 -336.6536 0.1500
4 61.8045 8.7396 1.49700 81.61
5 2894.6676 (d5)
6 88.7862 2.9891 1.92119 23.96
7 -438.2181 2.5010
8 -231.2935 0.7500 1.91082 35.25
9 56.0610 6.0344
10 -128.8456 2.5176 1.92119 23.96
11 -37.9268 0.7500 1.49700 81.61
12 36.2840 2.9048
13 -30.4597 0.7500 1.77250 49.62
14 441.8935 (d14)
15 (Aperture) ∞ 1.0000
16 116.6905 3.3524 1.80420 46.50
17 -56.9868 0.1500
18 62.0088 2.5615 1.49700 81.61
19 831.7727 0.2000
20 37.5078 5.1880 1.49700 81.61
21 -34.7643 0.7500 1.92119 23.96
22 57.0768 0.1500
23 22.7908 4.8756 1.80518 25.46
24 -135.2245 1.5919
25 -114.8545 0.7500 1.88300 40.80
26 25.3896 (d26)
27 98.6243 0.7500 1.90366 31.31
28 22.4440 5.4596 1.43700 95.10
29 -28.2688 0.3000
30 30.4060 3.1071 1.91082 35.25
31 873.9618 (d31)
32 145.1210 0.7500 1.91082 35.25
33 24.5579 (d33)
34 -39.7184 0.7500 1.49700 81.61
35 -465.5601 3.0356 1.92119 23.96
36 -39.9527 (d36)
37 ∞ 4.2000 1.51680 64.20
38∞ (BF)

[Various data]
Zoom ratio 3.90
Wide Angle Medium Telephoto Focal Length 50.01 95.11 195.00
F number 2.92 3.17 4.03
Full angle of view 2ω 24.08 12.67 6.23
Image height Y 10.82 10.82 10.82
Overall lens length 150.03 179.49 195.01

[Variable interval data]
wide-angle medium-telephoto
d0 ∞ ∞ ∞
d5 3.0000 32.5575 48.0271
d14 18.4771 15.5671 4.6256
d26 7.7211 2.4758 4.0761
d31 7.0504 2.4986 1.5000
d33 7.6940 12.3258 30.7083
d36 0.1500 8.1239 0.1500
BF 26.9522 26.9579 26.9424

[Lens group data]
Group Starting surface Focal length
G1 1 108.50
G2 6 -22.20
G3 15 38.68
G4 27 28.88
G5 32 -32.55
G6 34 97.46
G2a 6 -148.55
G2b 10 -26.49
G2ap 6 80.36
G2an 8 -49.48

[Value corresponding to conditional expression]
Conditional expression 1 Conditional expression 2 Conditional expression 3 Conditional expression 4 Conditional expression 5
Example f3ew/φm3w f3et/φm3t m3ew/m3et f2b/f2a f2ap/f2an
1 1.493 2.330 0.901 0.035 -1.225
2 1.232 1.445 0.782 0.081 -1.373
3 1.154 1.529 0.903 0.140 -1.702
4 1.457 2.365 0.972 0.192 -1.676
5 1.462 2.309 0.916 0.178 -1.624

G1 1st lens group G2 2nd lens group G2a 2a lens group G2ap 2ap lens group G2an 2an lens group G2b 2b lens group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group S Aperture diaphragm F Filter I Image plane

Claims (2)

In order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a negative lens group. It consists of a fifth lens group consisting of one lens with refractive power and a sixth lens group with positive refractive power . , a variable power imaging optical system, wherein the fifth lens group moves along the optical axis toward the image plane and satisfies the following conditional expression:
(1) 1.0<f3ew/Φm3w<1.75
(2) 1.2<f3et/Φm3t<3.0
(3) 0.7<m3ew/m3et<1.0
where f3ew: the combined focal length from the third lens group at the wide-angle end to the final lens group Φm3w: the value obtained by multiplying the paraxial marginal ray height at the top surface of the third lens group at the wide-angle end by the entrance pupil diameter f3et: at the telephoto end Composite focal length Φm3t from the third lens group to the final lens group: Value obtained by multiplying the paraxial marginal ray height at the leading surface of the third lens group at the telephoto end by the entrance pupil diameter m3ew: From the third lens group at the wide-angle end to the final lens group Combined lateral magnification up to lens group m3et: Combined lateral magnification from the third lens group at the telephoto end to the final lens group
In order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a negative lens group. It consists of a fifth lens group with a refractive power and a sixth lens group with a positive refractive power. During zooming, the distance between the adjacent lens groups changes, and when focusing from an object at infinity to a close object, the fifth lens The second lens group moves along the optical axis to the image plane side, and the second lens group is fixed with respect to the image plane during zooming. It is composed of the 2b lens group with negative refractive power, and the 2a lens group with negative refractive power is further composed of, in order from the object side, the 2ap lens group with positive refractive power and the 2an lens group with negative refractive power. A variable-magnification imaging optical system, characterized in that image stabilization is performed by displacing the 2b lens group in a direction perpendicular to the optical axis, and the following conditional expression is satisfied.
(1) 1.0<f3ew/Φm3w<1.75
(2) 1.2<f3et/Φm3t<3.0
(3) 0.7<m3ew/m3et<1.0
(4) 0.0<f2b/f2a<0.3
(5) -2.0<f2ap/f2an<-1.0
where f3ew: the combined focal length from the third lens group at the wide-angle end to the final lens group Φm3w: the value obtained by multiplying the paraxial marginal ray height at the top surface of the third lens group at the wide-angle end by the entrance pupil diameter f3et: at the telephoto end Composite focal length Φm3t from the third lens group to the final lens group: Value obtained by multiplying the paraxial marginal ray height at the leading surface of the third lens group at the telephoto end by the entrance pupil diameter m3ew: From the third lens group at the wide-angle end to the final lens group Composite lateral magnification m3et up to the lens group: Composite lateral magnification f2a from the third lens group at the telephoto end to the final lens group: Focal length f2b of the 2a lens group: Focal length of the 2b lens group f2ap: Focal length of the 2b lens group Focal length f2an: Focal length of the second an lens group

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