JP6326929B2 - Variable magnification imaging optical system with anti-vibration function - Google Patents

Description

  The present invention relates to a variable magnification imaging optical system used for a still camera, a video camera, and the like, and more particularly to a variable magnification imaging optical system having a narrow angle of view and further having an image stabilization function.

  Anti-vibration functions are being installed in imaging optical systems used in digital still cameras, etc., and failure due to camera shake has decreased even in photography using super-telephoto lenses, making super-telephoto lenses familiar. Yes. For this reason, an imaging optical system having a longer focal length and a narrow angle of view has been demanded.

  An imaging optical system in which the angle of view at the telephoto end corresponds to a focal length of 500 to 600 mm in terms of a 35 mm size is about 2 to 2.5 degrees is also described in the patent literature.

JP 2011-17912 A JP 2012-208434 A JP 2011-186095 A JP 2013-97322 A

  In a long focus imaging optical system with a narrow angle of view, it is first required to shorten the entire length of the optical system compared to the focal length. A value obtained by dividing the total length of the optical system by the focal length is called a telephoto ratio, and it is desirable that this value is sufficiently less than 1.

  To reduce the telephoto ratio, a so-called telephoto type or telephoto type in which a lens unit having a positive refractive power is arranged closest to the object side and a lens unit having a negative refractive power arranged closer to the image side than the lens group having a positive refractive power is used. In order to further reduce the telephoto ratio, the refractive power of the front positive group is made stronger than the refractive power of the entire system, and the imaging magnification of the rear negative group is increased. Since the imaging magnification of the rear negative group is large, the residual aberration in the front positive group is enlarged to form an image, so it is necessary to reduce the residual aberration in the front positive group.

  If the number of lens elements in the front positive group is maintained, it is necessary to increase the refractive power of each lens element, and chromatic aberration and spherical aberration generated by each lens element increase. Chromatic aberration and spherical aberration are corrected by combining a positive lens and a negative lens adjacent to each other, but if the amount of aberration generated by the adjacent positive lens and negative lens is large, the positional relationship between the adjacent positive lens and negative lens The change in aberration due to the shift of becomes large. In particular, the influence is large when eccentricity due to manufacturing errors occurs. Further, since the imaging magnification of the rear negative group is large, the fluctuation of aberration generated in the front positive group is enlarged.

  Because of these problems, the decentration must be suppressed to a very small level, particularly in the positive group in front of the long focus lens. If the diameter of the lens element is small, decentering can be suppressed by joining adjacent positive and negative lenses. However, when a lens element having a large diameter is joined, there is a risk that the joined lens may be peeled off or cracked when a temperature change occurs due to a difference in expansion coefficient of the material of each lens element. For this reason, for example, with a long focal length exceeding a focal length of 500 mm in a 35 mm size, it is often impossible to join in the front positive group having a large diameter.

  For this reason, there is a problem that it is easily affected by the eccentricity due to the manufacturing error, the manufacturing accuracy is required at a very high level, and the cost is increased.

  Further, in the long focal length lens, the diameter of the lens element is increased as a whole, especially on the object side, and the weight of the anti-vibration lens group tends to increase. Since the weight of the anti-vibration lens group is increased, it is necessary to increase the size of the actuator in order to increase the driving force of the actuator, which further increases the size of the lens barrel. On the contrary, if the driving force of the actuator is insufficient, a problem occurs in the responsiveness, the accuracy of correcting the camera shake is lowered, and the practicality of the product as a whole appears.

  In a super telephoto lens, image blur due to camera shake increases, and the displacement of the image stabilizing group in the direction perpendicular to the optical axis tends to increase. When the displacement of the vibration isolation group in the direction perpendicular to the optical axis increases, the radial size of the vibration isolation operation unit and the actuator increases, and the diameter of the entire lens barrel increases.

  Therefore, it is necessary to set the vibration-proof group as light as possible by suppressing the beam diameter, and the ratio of the displacement of the image in the direction perpendicular to the optical axis to the displacement in the direction perpendicular to the optical axis, that is, the vibration-proof coefficient. Must be sufficiently large to reduce the required displacement of the vibration isolation group.

  Like the anti-vibration group, the focus group tends to have a large weight and displacement in the long focal length lens, and it is a problem to suppress the beam diameter and secure the focus sensitivity.

  Although the optical system described in Patent Document 1 achieves a good reduction in the optical total length at the telephoto end, it is difficult to suppress the diameter of the lens barrel because the vibration isolation group has a large diameter and a low vibration isolation coefficient. In addition, a cemented lens is included in the first lens group, and cracking or peeling due to temperature change may occur.

  The optical system described in Patent Document 2 has a telephoto ratio at the telephoto end of approximately 0.77, but it is desired to further shorten it. Furthermore, since the light diameter of the focus group is particularly high at the wide-angle end, a problem remains in the weight of the focus group. There is also described an optical system in which the lens of the first lens group is configured without being joined and there is no possibility of cracking or peeling due to temperature change. However, there is a difference between the most negative lens on the object side and the positive lens on the image side. The core sensitivity is very high, and it is necessary to increase the assembly accuracy, which increases the cost.

  The optical system described in Patent Document 3 corresponds to an image circle having a radius of about 11 mm, has a telephoto ratio of less than 0.65, and has a very short optical total length. However, there is no mention of image stabilization. Further, if the image circle radius is expanded to about 22 mm, the diameter of the first lens group becomes large, so that there is a possibility that the cemented lens included in the first lens group may crack or peel off due to temperature change.

  The optical system described in Patent Document 4 has a telephoto ratio of about 0.65 and a very short optical total length. However, the diameter of the anti-vibration group is too large, and it is difficult to reduce the weight even though the anti-vibration group has one structure. It is enough. In addition, a cemented lens is included in the first lens group, and cracking or peeling due to temperature change may occur.

  The present invention has been made in view of such a situation. In a variable magnification imaging optical system having a half angle of view at the telephoto end of about 2 degrees, a large image circle, and a long focal length at the telephoto end, the front group is manufactured. An object of the present invention is to provide a variable magnification imaging optical system having an anti-vibration function with reduced error sensitivity and reduced weight of the anti-vibration group.

In order to solve the above problem, in the variable magnification imaging optical system having the image stabilization function according to the first aspect of the invention, in order from the object side, a first lens group having a positive refractive power and a second lens having a negative refractive power And a rear lens group having a positive refractive power as a whole over the entire range of zooming, the air spacing between the lens groups changes during zooming, and the first lens group is composed of at least two lens groups. One lens group is composed of three lenses, a first negative lens, a first positive lens, and a second positive lens, which are spaced in order from the object side with an air gap, and the second lens group is in order from the object side. It is composed of a negative refractive power group 2a and a negative refractive power group 2b, and the vibration is prevented by displacing the 2b group in a direction perpendicular to the optical axis, and the following conditions are satisfied.
(1) 2.40 <(1 / Rg21-1 / fg1) * ft <4.25
(2) −0.95 <β2b <−0.65
However,
fg1: Focal length Rg21 of the first negative lens: radius of curvature of the object-side surface of the first positive lens ft: synthetic focal length β2b in the entire system at the telephoto end and infinite distance imaging state: telephoto end and infinite distance in the group 2b Imaging magnification in imaging state

In the variable magnification imaging optical system having the image stabilization function of the second invention, the following conditions are further satisfied in the first invention.
(3) 0.95 <fp1 / fp2 <1.55
However,
fp1: Focal length of the first positive lens fp2: Focal length of the second positive lens

  In the variable magnification imaging optical system having the image stabilization function of the third aspect of the invention, in the first or second aspect of the invention, the second lens group is fixed to the image plane at the time of zooming. .

  In the variable magnification imaging optical system having the image stabilization function of the fourth invention, in the first to third inventions, the rear lens group further includes a third lens group having a positive refractive power closest to the object side. I decided to prepare.

  In the variable magnification imaging optical system having the image stabilization function of the fifth invention, in the first to fourth inventions, in the rear lens group, the entire lens group provided closest to the image side, or the most Among the lens groups provided on the image side, focusing is performed by using the partial lens group positioned closest to the image side as a focusing lens group, and the focusing lens group has a negative refractive power as a whole.

  According to the present invention, in a variable magnification imaging optical system having a half field angle of about 2 degrees at the telephoto end, a large image circle, and a long focal length at the telephoto end, the manufacturing error sensitivity of the front group is reduced, and A variable magnification imaging optical system having an anti-vibration function with reduced weight can be provided.

It is a lens block diagram at the time of wide-angle end of the imaging optical system of Example 1 of this invention at the time of infinity focusing. FIG. 6 is a longitudinal aberration diagram of an object at infinity according to Example 1 of the present invention, in which a is the wide-angle end, b is the intermediate focal length (269.96 mm), and c is the aberration diagram at the telephoto end. FIG. 6 is a lateral aberration diagram in a standard state of an object at infinity according to Example 1 of the present invention, where a is an aberration angle at a wide angle end, b is an intermediate focal length (269.96 mm), and c is an aberration diagram at a telephoto end. It is a lateral aberration figure at the time of image stabilization in the infinite object of Example 1 of this invention, a is a wide angle end at the time of 0.44 mm displacement, b is the intermediate focal distance (269.96 mm) at the time of 0.59 mm displacement, c Is an aberration diagram at the telephoto end when 0.90 mm is displaced. It is a lens block diagram at the time of wide-angle end of the imaging optical system of Example 2 of this invention at the time of infinity focusing. FIG. 6 is a longitudinal aberration diagram of an object at infinity according to Example 2 of the present invention, in which a is the wide-angle end, b is the intermediate focal length (269.95 mm), and c is the aberration diagram at the telephoto end. It is a lateral aberration figure in the standard state in the infinite object of Example 2 of this invention, a is a wide-angle end, b is an intermediate | middle focal distance (269.95 mm), c is an aberration figure of a telephoto end. It is a lateral aberration figure at the time of image stabilization in the infinite object of Example 2 of the present invention, a is a wide angle end when 0.45 mm displacement, b is an intermediate focal length (269.95 mm) when 0.59 mm displacement, c Is an aberration diagram at the telephoto end when 0.90 mm is displaced. It is a lens block diagram at the time of wide-angle end focusing on infinity at the wide angle end of Example 3 of the present invention. It is a longitudinal aberration figure in the infinite object of Example 3 of this invention, a is a wide angle end, b is an intermediate | middle focal distance (270.03 mm), c is an aberration figure of a telephoto end. It is a lateral aberration figure in the standard state in the infinite object of Example 3 of this invention, a is a wide angle end, b is an intermediate focal distance (270.03 mm), c is an aberration figure of a telephoto end. It is a lateral aberration figure at the time of vibration-proof in the infinite object of Example 3 of this invention, a is a wide angle end at the time of 0.48 mm displacement, b is the intermediate focal length (270.03 mm) at the time of 0.60 mm displacement, c Is an aberration diagram at the telephoto end when the displacement is 0.85 mm. It is a lens block diagram at the time of wide-angle end of the imaging optical system of Example 4 of this invention at the time of infinity focusing. FIG. 10 is a longitudinal aberration diagram of an object at infinity according to Example 4 of the present invention, in which a is the wide-angle end, b is the intermediate focal length (270.03 mm), and c is the aberration diagram at the telephoto end. FIG. 10 is a lateral aberration diagram in a standard state of an infinite object according to Example 4 of the present invention, where a is an aberration angle at a wide angle end, b is an intermediate focal length (270.03 mm), and c is an aberration diagram at a telephoto end. FIG. 10 is a lateral aberration diagram during vibration isolation of an infinite object according to Example 4 of the present invention, where a is the wide-angle end when the displacement is 0.44 mm, b is the intermediate focal length (270.03 mm) when the displacement is 0.56 mm, and c. Is an aberration diagram at the telephoto end when 0.79 mm is displaced. It is a lens block diagram at the time of an infinite point focusing on the wide angle end of the imaging optical system of Example 5 of the present invention. FIG. 6 is a longitudinal aberration diagram of an object at infinity according to Example 5 of the present invention, where a is an aberration angle at a wide angle end, b is an intermediate focal length (270.03 mm), and c is an aberration diagram at a telephoto end. FIG. 10 is a lateral aberration diagram in a standard state of an object at infinity according to Example 5 of the present invention, where a is an aberration angle at a wide angle end, b is an intermediate focal length (270.03 mm), and c is an aberration diagram at a telephoto end. FIG. 11 is a lateral aberration diagram during vibration isolation of an infinitely distant object according to Example 5 of the present invention, where a is the wide-angle end when the displacement is 0.49 mm, b is the intermediate focal length (270.03 mm) when the displacement is 0.62 mm, and c. Is an aberration diagram at the telephoto end when 0.88 mm is displaced. It is a lens block diagram at the time of an infinite focus by the wide angle end of the imaging optical system of Example 6 of this invention. FIG. 10 is a longitudinal aberration diagram of an object at infinity according to Example 6 of the present invention, where a is an aberration angle at a wide angle end, b is an intermediate focal length (250.18 mm), and c is an aberration diagram at a telephoto end. FIG. 10 is a lateral aberration diagram in a standard state of an infinite object according to Example 6 of the present invention, where a is an aberration angle at a wide angle end, b is an intermediate focal length (250.18 mm), and c is an aberration diagram at a telephoto end. It is a lateral aberration figure at the time of image stabilization in the infinite object of Example 6 of this invention, a is a wide-angle end at the time of 0.39 mm displacement, b is the intermediate focal distance (250.18 mm) at the time of 0.54 mm displacement, c Is an aberration diagram at the telephoto end when 0.88 mm is displaced.

  The variable magnification imaging optical system having the image stabilization function of the present invention is positive in order from the object side as shown in the lens configuration diagrams shown in FIGS. 1, 5, 9, 13, 17, and 21. The first lens group G1 having a refractive power, the second lens group G2 having a negative refractive power, and at least two lens groups subsequent to the second lens group G1, and has a positive refractive power as a whole over the entire zoom range. The rear lens group Gr.

  Each lens group is separated by an air interval, and the interval between the lens groups changes during zooming. The first lens group G1 includes a first negative lens, a first positive lens, and a second positive lens that are spaced apart from each other in order from the object side. The second lens group G2 includes a negative refractive power 2a group G2a and a negative refractive power 2b group G2b in order from the object side, and performs vibration isolation by displacing the 2b group in a direction orthogonal to the optical axis.

  In the present invention, in order to suppress the total length while increasing the focal length at the telephoto end, the first lens group G1 having a positive refractive power and the second lens group G2 having a negative refractive power are arranged in order from the object side. This constitutes the refractive power arrangement of the mold. The zooming from the wide-angle end to the telephoto end is performed mainly by increasing the distance between the first lens group G1 and the second lens group G2.

  Further, with the zooming from the wide-angle end to the telephoto end, the distance between the second lens group G2 and the rear lens group Gr decreases, and the refractive power of the combined system of the second lens group G2 and the rear lens group Gr has a negative direction. To change. By this action, the telephoto refractive power arrangement formed by the combined system of the first lens group G1, the second lens group G2, and the rear lens group Gr becomes stronger from the wide-angle end toward the telephoto end. At the wide-angle end, the total length of the optical system is relatively long with respect to the total focal length of the entire system, and at the telephoto end, the total length of the optical system is relatively short with respect to the total focal length of the entire system. The amount can be reduced.

  The first lens group G1 includes three lenses, a first negative lens, a first positive lens, and a second positive lens. The three lenses are separated by an air interval and are not joined. As mentioned above, the diameter of the lens on the most object side of the long-focus optical system becomes very large, and there is a possibility that the glass material will be peeled off due to the difference in the expansion coefficient of the glass with temperature change, so that cracking may occur. Not in. However, the adjacent positive lens and negative lens cancel each other out aberrations, and the aberration variation due to the relative position error is significant. In particular, the positive lens and the negative lens that are closest to each other on the object side are responsible for correcting spherical aberration, and there is a tendency for decentration coma to occur greatly when decentration error occurs.

  If the number of positive lenses in the first lens group G1 is further increased, the burden of aberration per positive lens can be reduced, and fluctuations in eccentric coma due to manufacturing errors can be suppressed. The weight of group G1 will increase. When the weight of the first lens group G1 away from the camera is increased, the moment around the camera is increased, which imposes a burden when the photographer holds the lens barrel by hand. Therefore, it is desirable to avoid an increase in the number of first lens group G1.

The second lens group G2 has a significantly smaller beam diameter than the first lens group G1, and is suitable for reducing the weight of the image stabilizing group by using it as an image stabilizing group. Further, the second lens group G2 is divided into the 2a group G2a and the 2b group G2b in order from the object side, and only the 2b group G2b having a lower light beam diameter arranged on the image side is used for image stabilization. Suitable for weight reduction.

  Further, the relationship between the beam diameter and the image stabilization coefficient in the 2b group G2b will be described. The radius of the entrance pupil of the entire system is R, the focal length of the synthesis system on the object side from the 2b group G2b is ff, the focal length of the 2b group G2b is f2b, the object side focus of the 2b group G2b is synthesized on the object side from the 2b group G2b When the distance to the focal point of the system is z2b, the imaging magnification of the 2b group G2b is β2b, the combined focal length of the entire system is f, and the imaging magnification of the synthesis system on the image side of the 2b group G2b is βr, the group 2b The incident height R2 of the axial marginal ray on the object side principal plane of G2b can be expressed by the following reference formula (1).

Reference formula (1) R2 = (z2b−f2b) * R / ff
= (1 / β2b-1) * f2b * R / {f / (β2b * βr)}
= (1-β2b) * βr * R * f2b / f

  Here, the value of (1-β2b) * βr is known as the ratio of the displacement of the image in the direction perpendicular to the optical axis to the displacement in the direction orthogonal to the optical axis of the image stabilization group, that is, the image stabilization coefficient. Therefore, the smaller the anti-vibration coefficient, the smaller the diameter of the anti-vibration group.

  When it is assumed that the focal length of the synthesis system closer to the object side than the 2b group G2b is ff and the focal length f of the entire system is a constant, the relationship of the following reference equation (2) is established.

Reference formula (2) β2b * βr = f / ff = C (constant)

  Substituting this into reference equation (1) leads to reference equation (3).

Reference formula (3) R2 = (1 / β2b-1) * C * R * f2b / f

  Assuming that β2b <0, if the absolute value of β2b is large, the distance z2b from the focal point of the 2b group G2b to the focal point of the composite system closer to the object side than the 2b group G2b becomes small, and the object side main of the 2b group G2b Although the height R2 of the on-axis marginal ray in the plane is reduced, on the other hand, the absolute value of the image stabilization coefficient is decreased, and the amount of movement of the image stabilization group corresponding to the same image blur amount is increased.

  In order to suppress the diameter of the lens barrel, inconvenience occurs if the imaging magnification of the 2b group G2b is too large or too small. As is clear from the reference equations (1) and (3), the smaller the ratio of the focal length of the 2b group G2b to the total focal length of the entire system, the higher the on-axis marginal ray height R2 in the object-side principal plane of the 2b group G2b. Becomes smaller.

Conditional expression (1) satisfied by the variable magnification imaging optical system having the image stabilization function of the present invention defines a desirable range for suppressing performance change due to relative decentering of the first negative lens and the first positive lens. is there.
(1) 2.40 <(1 / Rg21-1 / fg1) * ft <4.25
However,
fg1: focal length Rg21 of the first negative lens: radius of curvature of the object-side surface of the first positive lens ft: composite focal length at the telephoto end and infinitely far-end imaging state of the entire system

  If the upper limit of conditional expression (1) is exceeded, the incident angle of the on-axis marginal ray on the object-side surface of the first positive lens becomes tight, and the occurrence of spherical aberration on the object-side surface of the first positive lens increases. Thus, the sensitivity of the fluctuation of the eccentric coma with respect to the eccentricity of the first positive lens becomes very high.

  Below the lower limit of conditional expression (1), the radius of curvature of the object-side surface of the first positive lens increases, or the refractive power of the first negative lens decreases.

  If the radius of curvature of the object-side surface of the first positive lens becomes too large, the burden of the positive refracting power on the surface will be reduced, and that amount will be borne by other surfaces. If the refractive power of the entire first lens group G1 remains unchanged, the number of surfaces that bear positive refractive power decreases, and the generation of spherical aberration in the entire system increases, resulting in poor imaging performance.

  If the refractive power of the first negative lens becomes too small, it becomes difficult to correct the chromatic aberration of the first lens group G1, and the imaging performance is also deteriorated.

  At the time of image stabilization, the position of the light beam that forms an image at the same position on the image plane passes through the first lens group G1 varies. For this reason, the deterioration of the aberration correction status in the first lens group G1 as described above is generally a factor for increasing the aberration fluctuation during the image stabilization. For this reason, in an imaging optical system having an anti-vibration function, if the value falls below the lower limit of conditional expression (1), the performance degradation at the time of anti-vibration becomes large, which is particularly undesirable.

  If the upper limit of conditional expression (1) is set to 4.2, the upper limit is further set to 4.0, or the lower limit of conditional expression (1) is set to 2.7, and further the lower limit is set to 2.9, the above-mentioned effect is more reliably achieved. Can be achieved.

Conditional expression (2) satisfied by the variable magnification imaging optical system having the image stabilization function of the present invention relates to the imaging magnification of the 2b group G2b, and a desirable range for the suppression of the beam diameter of the 2b group G2b and the displacement amount during image stabilization. It prescribes.
(2) −0.95 <β2b <−0.65
However,
β2b: Imaging magnification in the telephoto end and infinitely far-end imaging state of the 2b group G2b

  If the upper limit of conditional expression (2) is exceeded, the necessary amount of movement of the vibration isolation group increases, and it becomes difficult to suppress the diameter of the lens barrel. Since β2b = f2b / z2b from the paraxial imaging relationship, and f2b <0 and z2b> 0 from β2b <0, the value of z2b increases below the lower limit of the conditional expression (2), and the 2b group G2b The focal position of the object side synthesizing system moves further to the image side with respect to the object side focal point of the 2b group G2b and moves away from the 2b group G2b. Therefore, it is difficult to suppress the axial beam diameter in the 2b group G2b at the telephoto end, which is disadvantageous in terms of weight reduction of the vibration proof group.

  When the upper limit of conditional expression (2) is -0.72, the upper limit is further -0.75, the lower limit of conditional expression (2) is -0.93, and the lower limit is -0.91, the above-mentioned effect Can be achieved more reliably.

Further, it is desirable that the variable magnification imaging optical system having the image stabilization function of the present invention satisfies the conditional expression (3). Conditional expression (3) relates to the power ratio between the first positive lens and the second positive lens, and in particular defines a desirable range for suppressing performance change due to eccentricity of the first positive lens.
(3) 0.95 <fp1 / fp2 <1.55
However,
fp1: Focal length of the first positive lens fp2: Focal length of the second positive lens

  Compared to the first positive lens adjacent to the first negative lens, the eccentricity of the second positive lens is less likely to cause large aberration fluctuations. Therefore, the refractive power of the first positive lens is reduced by increasing the refractive power of the second positive lens compared to the first positive lens, and the spherical aberration generated by the first positive lens is suppressed, thereby reducing the refractive power of the first negative lens. It is possible to suppress the fluctuation of the eccentric coma accompanying the relative eccentricity of the first positive lens.

  When the refractive power of the first positive lens decreases beyond the upper limit value of conditional expression (3), the burden of refractive power is excessively concentrated on the second positive lens, and the generation of spherical aberration in the second positive lens increases. The spherical aberration of the entire system is deteriorated.

  If the refractive power of the first positive lens increases beyond the lower limit of conditional expression (3), the suppression of spherical aberration generated by the first positive lens becomes insufficient, and the eccentric coma accompanying the eccentricity of the first lens group. Aberration sensitivity is too high.

  If the upper limit of conditional expression (3) is set to 1.5, the upper limit is further set to 1.45, or the lower limit of conditional expression (3) is set to 0.98, and the lower limit is further set to 1.00, the above-mentioned effect will be more sure. Can be achieved.

  Further, in the variable magnification imaging optical system having the image stabilization function of the present invention, it is desirable that the second lens group is fixed with respect to the image plane at the time of zooming. The second lens group includes the 2b group that is a vibration-proof group, and there is an advantage that the wiring for control can be easily arranged by fixing the vibration-proof group. In addition, the moving mechanism of the lens unit during zooming can be simplified.

  Furthermore, it is desirable that the variable magnification imaging optical system having the image stabilization function of the present invention includes the third lens group having a positive refractive power on the most object side of the rear lens group. By making the third lens group having a positive refractive power approach the second lens group having a negative refractive power at the telephoto end, the negative refraction of the combined system of the second lens group and the third lens group at the telephoto end is achieved. This is effective for shortening the total optical length at the telephoto end.

  Further, the variable magnification imaging optical system having the image stabilization function of the present invention is the entire lens group provided closest to the image side or the most image side of the lens groups provided closest to the image side in the rear lens group. It is desirable that focusing is performed with the partial lens group positioned at a focusing lens group, and the focusing lens group as a whole has a negative refractive power.

  In the long focus lens, the defocus amount for focusing to a short distance becomes large. Considering the improvement of the autofocus drive speed, two points are achieved: first, the focusing lens group is lightweight, and second, the amount of movement of the image plane relative to the unit movement amount of the focusing lens group is large. It is desirable.

  In order to shorten the total optical length of the imaging optical system compared to the focal length, it is effective to provide a lens group or partial lens group having a strong negative refractive power on the most image side of the imaging optical system. By using a lens group or partial lens group that has a strong negative refractive power to shorten the overall length of the optical system as a focusing lens group, the amount of movement of the image plane per unit movement amount of the focusing lens group can be increased.

  At the same time, since it is on the image side, the light beam is converged and its diameter is reduced. By using this negative refractive power lens group or partial lens group as a focusing lens group, the above-mentioned problems can be achieved simultaneously.

  In the imaging optical system of the present invention, it is more effective to accompany the following configuration.

  More preferably, the rear lens group includes a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power in order from the object side.

  The 2b group is more preferably composed of three or less lenses including one positive lens. When the number is four or more, it is difficult to suppress the weight of the vibration isolation group.

  In addition, in order to correct the chromatic aberration of the 2b group and suppress the occurrence of lateral chromatic aberration during image stabilization, it is desirable to have at least one positive lens in the 2b group. In addition, it is desirable to suppress the occurrence of spherical aberration, coma aberration, and the like while maintaining the negative refractive power of the 2b group sufficiently by having two negative lenses in the 2b group.

  Next, a lens configuration of an example according to the imaging optical system of the present invention will be described. In the following description, the lens configuration is described in order from the object side to the image 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 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and The fifth lens group G5 has a negative refractive power. A synthesis system from the third lens group G3 to the fifth lens group G5 corresponds to the rear lens group Gr.

  The first lens group G1 includes a negative meniscus lens L1 having a convex surface facing the object side, a biconvex lens L2, and a positive meniscus lens L3 having a convex surface facing the object side. The negative meniscus lens L1 corresponds to the first negative lens, the biconvex lens L2 corresponds to the first positive lens, and the positive meniscus lens L3 corresponds to the second positive lens.

  The second lens group G2 is composed of a negative refractive power 2a group G2a and a negative refractive power 2b group G2b in this order from the object side, and only the 2b group G2b is displaced in a direction perpendicular to the optical axis to prevent vibration. I do. The 2a group G2a is composed of a biconcave lens L4. The 2b group G2b includes a biconcave lens L5 and a cemented lens including a biconcave lens L6 and a biconvex lens L7.

  The third lens group G3 includes a biconvex lens L8, a positive meniscus lens L9 having a convex surface directed toward the object side, a cemented lens composed of a biconvex lens L10, a biconcave lens L11, and a biconvex lens L12, a biconvex lens L13, and a biconcave lens. The lens includes a cemented lens composed of L14 and a cemented lens composed of a biconcave lens L15 and a biconvex lens L16.

  The fourth lens group G4 includes a biconvex lens L17 and a cemented lens including a biconvex lens L18 and a biconcave lens L19.

  The fifth lens group G5 includes a negative meniscus lens L20 having a convex surface directed toward the object side, a cemented lens including a biconvex lens L21 and a biconcave lens L22, and a cemented lens including a biconcave lens L23 and a biconvex lens L24. The entire fifth lens group G5 moves toward the image side during focusing from infinity to a short distance.

  FIG. 5 is a lens configuration diagram of the imaging optical system according to the second embodiment of the present invention.

  In order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and The fifth lens group G5 has a negative refractive power. A synthesis system from the third lens group G3 to the fifth lens group G5 corresponds to the rear lens group Gr.

  The first lens group G1 includes a negative meniscus lens L1 having a convex surface facing the object side, a biconvex lens L2, and a positive meniscus lens L3 having a convex surface facing the object side. The negative meniscus lens L1 corresponds to the first negative lens, the biconvex lens L2 corresponds to the first positive lens, and the positive meniscus lens L3 corresponds to the second positive lens.

  The second lens group G2 is composed of a negative refractive power 2a group G2a and a negative refractive power 2b group G2b in this order from the object side, and only the 2b group G2b is displaced in a direction perpendicular to the optical axis to prevent vibration. I do. The 2a group G2a is composed of a biconcave lens L4. The 2b group G2b includes a biconcave lens L5 and a cemented lens including a biconcave lens L6 and a biconvex lens L7.

  The third lens group G3 includes a biconvex lens L8, a positive meniscus lens L9 having a convex surface directed toward the object side, a cemented lens composed of a biconvex lens L10, a biconcave lens L11, and a biconvex lens L12, a biconvex lens L13, and a biconcave lens. The lens includes a cemented lens composed of L14 and a cemented lens composed of a biconcave lens L15 and a biconvex lens L16.

  The fourth lens group G4 includes a biconvex lens L17 and a cemented lens including a biconvex lens L18 and a biconcave lens L19.

  The fifth lens group G5 includes a negative meniscus lens L20 having a convex surface directed toward the object side, a cemented lens including a biconvex lens L21 and a biconcave lens L22, and a cemented lens including a biconcave lens L23 and a biconvex lens L24. The entire fifth lens group G5 moves toward the image side during focusing from infinity to a short distance.

  FIG. 9 is a lens configuration diagram of the imaging optical system according to Example 3 of the present invention.

  In order from the object side, the first lens group G1 having a positive refractive power, the second lens group G2 having a negative refractive power, the third lens group G3 having a positive refractive power, and the fourth lens group G4 having a positive refractive power. Composed. A synthesis system from the third lens group G3 to the fourth lens group G4 corresponds to the rear lens group Gr.

  The first lens group G1 includes a negative meniscus lens L1 having a convex surface directed toward the object side, a biconvex lens L2, and a biconvex lens L3. The negative meniscus lens L1 corresponds to the first negative lens, the biconvex lens L2 corresponds to the first positive lens, and the biconvex lens L3 corresponds to the second positive lens.

  The second lens group G2 is composed of a negative refractive power 2a group G2a and a negative refractive power 2b group G2b in this order from the object side, and only the 2b group G2b is displaced in a direction perpendicular to the optical axis to prevent vibration. I do. The 2a group G2a includes a positive meniscus lens L4 having a convex surface directed toward the object side and a biconcave lens L5. The 2b group G2b includes a cemented lens including a biconcave lens L6, a positive meniscus lens L7 having a convex surface facing the object side, and a negative meniscus lens L8 having a convex surface facing the image side.

  The third lens group G3 includes a biconvex lens L9, a biconvex lens L10, a cemented lens including a biconvex lens L11 and a biconcave lens L12, and a cemented lens including a biconvex lens L13 and a biconcave lens L14.

  The fourth lens group G4 includes, in order from the object side, a 4a group G4a having a positive refractive power and a 4b group G4b having a negative refractive power. The 4a group G4a and the 4b group G4b move together during zooming, and only the 4b group G4b moves toward the image side during focusing from an infinite distance to a short distance.

  The 4a group G4a includes a biconvex lens L15 and a cemented lens including a biconvex lens L16 and a biconcave lens L17. The 4b group G4b includes a negative meniscus lens G18 having a convex surface directed toward the object side, and a cemented lens including a biconcave lens G19 and a biconvex lens G20.

  FIG. 13 is a lens configuration diagram of the imaging optical system according to Example 4 of the present invention.

  In order from the object side, the first lens group G1 having a positive refractive power, the second lens group G2 having a negative refractive power, the third lens group G3 having a positive refractive power, and the fourth lens group G4 having a positive refractive power. Composed. A synthesis system from the third lens group G3 to the fourth lens group G4 corresponds to the rear lens group Gr.

  The first lens group G1 includes a negative meniscus lens L1 having a convex surface directed toward the object side, a biconvex lens L2, and a biconvex lens L3. The negative meniscus lens L1 corresponds to the first negative lens, the biconvex lens L2 corresponds to the first positive lens, and the biconvex lens L3 corresponds to the second positive lens.

  The second lens group G2 is composed of a negative refractive power 2a group G2a and a negative refractive power 2b group G2b in this order from the object side, and only the 2b group G2b is displaced in a direction perpendicular to the optical axis to prevent vibration. I do. The 2a group G2a includes a positive meniscus lens L4 having a convex surface directed toward the object side and a biconcave lens L5. The 2b group G2b includes a cemented lens including a biconcave lens L6, a positive meniscus lens L7 having a convex surface facing the object side, and a negative meniscus lens L8 having a convex surface facing the image side.

  The third lens group G3 includes a biconvex lens L9, a biconvex lens L10, a cemented lens including a biconvex lens L11 and a biconcave lens L12, and a cemented lens including a biconvex lens L13 and a biconcave lens L14.

  The fourth lens group G4 includes, in order from the object side, a 4a group G4a having a positive refractive power and a 4b group G4b having a negative refractive power. The 4a group G4a and the 4b group G4b move together during zooming, and only the 4b group G4b moves toward the image side during focusing from an infinite distance to a short distance.

  The 4a group G4a includes a biconvex lens L15 and a cemented lens including a biconvex lens L16 and a biconcave lens L17. The 4b group G4bG4b includes a negative meniscus lens G18 having a convex surface directed toward the object side, and a cemented lens including a biconcave lens G19 and a biconvex lens G20.

  FIG. 17 is a lens configuration diagram of the imaging optical system according to Example 5 of the present invention.

  In order from the object side, the first lens group G1 having a positive refractive power, the second lens group G2 having a negative refractive power, the third lens group G3 having a positive refractive power, and the fourth lens group G4 having a positive refractive power. Composed. A synthesis system from the third lens group G3 to the fourth lens group G4 corresponds to the rear lens group Gr.

  The first lens group G1 includes a negative meniscus lens L1 having a convex surface directed toward the object side, a biconvex lens L2, and a biconvex lens L3. The negative meniscus lens L1 corresponds to the first negative lens, the biconvex lens L2 corresponds to the first positive lens, and the biconvex lens L3 corresponds to the second positive lens.

  The second lens group G2 is composed of a negative refractive power 2a group G2a and a negative refractive power 2b group G2b in this order from the object side, and only the 2b group G2b is displaced in a direction perpendicular to the optical axis to prevent vibration. I do. The 2a group G2a includes a positive meniscus lens L4 having a convex surface directed toward the object side and a biconcave lens L5. The 2b group G2b includes a cemented lens including a biconcave lens L6, a positive meniscus lens L7 having a convex surface facing the object side, and a negative meniscus lens L8 having a convex surface facing the image side.

  The third lens group G3 includes a biconvex lens L9, a biconvex lens L10, a cemented lens including a biconvex lens L11 and a biconcave lens L12, and a cemented lens including a biconvex lens L13 and a biconcave lens L14.

  The fourth lens group G4 includes, in order from the object side, a 4a group G4a having a positive refractive power and a 4b group G4b having a negative refractive power. The 4a group G4a and the 4b group G4b move together during zooming, and only the 4b group G4b moves toward the image side during focusing from an infinite distance to a short distance.

  The 4a group G4a includes a biconvex lens L15 and a cemented lens including a biconvex lens L16 and a biconcave lens L17. The 4b group G4b includes a negative meniscus lens G18 having a convex surface directed toward the object side, and a cemented lens including a biconcave lens G19 and a biconvex lens G20.

  FIG. 21 is a lens configuration diagram of the imaging optical system according to Example 6 of the present invention.

  In order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and The fifth lens group G5 has a negative refractive power. A synthesis system from the third lens group G3 to the fifth lens group G5 corresponds to the rear lens group Gr.

  The first lens group G1 includes a negative meniscus lens L1 having a convex surface facing the object side, a biconvex lens L2, and a plano-convex lens L3 having a convex surface facing the object side. The negative meniscus lens L1 corresponds to the first negative lens, the biconvex lens L2 corresponds to the first positive lens, and the plano-convex lens L3 corresponds to the second positive lens.

  The second lens group includes a negative refractive power 2a group G2a and a negative refractive power 2b group G2b in order from the object side, and only the 2b group G2b is displaced in a direction perpendicular to the optical axis to prevent vibration. Do. The 2a group G2a includes a plano-concave lens L4 having a concave surface facing the image side. The 2b group G2b includes a biconcave lens L5 and a cemented lens including a biconcave lens L6 and a biconvex lens L7.

  The third lens group G3 includes a biconvex lens L8, a positive meniscus lens L9 having a convex surface directed toward the object side, a cemented lens composed of a biconvex lens L10, a biconcave lens L11, and a biconvex lens L12, a biconvex lens L13, and a biconcave lens. The lens includes a cemented lens composed of L14 and a cemented lens composed of a biconcave lens L15 and a biconvex lens L16.

  The fourth lens group G4 includes a biconvex lens L17 and a cemented lens including a biconvex lens L18 and a biconcave lens L19.

  The fifth lens group G5 includes a negative meniscus lens L20 having a convex surface directed toward the object side, a cemented lens including a biconvex lens L21 and a biconcave lens L22, and a cemented lens including a biconcave lens L23 and a biconvex lens L24. The entire fifth lens group G5 moves toward the image side during focusing from infinity to a short distance.

  Specific numerical data of each embodiment of the imaging optical system of the present invention described above will be shown below.

  In [Surface data], the surface number is the number of the lens surface or aperture stop counted from the object side, r is the radius of curvature of each surface, d is the distance between the surfaces, nd is the refractive index with respect to the d-line (wavelength 587.56 nm). , Vd indicate Abbe numbers for the d line.

  The (diaphragm) attached to the surface number indicates that the aperture stop is located at that position. ∞ (infinity) is entered in the radius of curvature for a plane or aperture stop.

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

  [Variable interval data] indicates the variable interval and the value of BF in each focal length state.

  [Lens Group Data] indicates the surface number of the most object side constituting each lens group and the combined focal length of the entire group.

  In all the values of the following specifications, the focal length f, the radius of curvature r, the lens surface interval d, and other length units described are in millimeters (mm) unless otherwise specified. In the system, the same optical performance can be obtained even in proportional expansion and proportional reduction, and the present invention is not limited to this.

  In addition, a list of corresponding values of the conditional expressions in each of these examples is shown.

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

Numerical example 1
Unit: mm
[Surface data]
Surface number rd nd vd
1 481.7525 3.0000 1.80611 40.73
2 198.6329 4.0183
3 358.8891 8.8572 1.43700 95.10
4 -355.7759 0.1500
5 130.4780 11.3725 1.43700 95.10
6 5914.4913 (d6)
7 -3492.1288 1.2000 1.48749 70.44
8 199.0207 7.9584
9 -261.4650 0.8000 1.69680 55.46
10 70.8680 3.1913
11 -70.5567 0.8000 1.69680 55.46
12 70.5567 3.1562 1.84666 23.78
13 -539.3451 (d13)
14 90.7782 3.2278 1.80610 33.27
15 -348.4940 0.1500
16 64.3291 3.3629 1.58913 61.25
17 539.6359 0.7294
18 51.6072 6.6909 1.49700 81.61
19 -89.3779 1.0000 1.80610 33.27
20 193.2822 4.0649 1.49700 81.61
21 -147.5437 1.5690
22 34.1240 4.6996 1.58144 40.89
23 -1023.3555 0.9000 1.91082 35.25
24 28.9467 3.4543
25 -57.9952 0.9000 2.00100 29.13
26 215.7552 2.3577 1.62004 36.30
27 -91.7648 2.0000
28 (Aperture) ∞ (d28)
29 78.5867 3.4125 1.64769 33.84
30 -59.9898 0.1500
31 37.3123 4.3027 1.48749 70.44
32 -56.5416 0.9000 1.95375 32.32
33 315.8381 (d33)
34 75.3458 0.8000 1.84666 23.78
35 26.1306 5.3276
36 255.6785 2.5624 1.69895 30.05
37 -57.2849 0.8000 1.72916 54.67
38 298.2516 2.2898
39 -34.6488 1.8081 1.49700 81.61
40 34.6488 5.7346 1.72342 37.99
41 -66.6029 (BF)
Image plane ∞


[Various data]
Zoom ratio 3.78
Wide angle Medium telephoto Focal length 154.59 269.96 583.65
F number 5.06 5.83 6.49
Full angle of view 2ω 15.73 9.04 4.18
Image height Y 21.63 21.63 21.63
Total lens length 329.06 372.87 419.53


[Variable interval data]
Wide angle Medium telephoto
d6 99.5006 143.3142 189.9726
d13 29.3765 18.6488 3.5000
d28 24.1792 18.7262 13.4529
d33 11.7143 10.2186 2.0000
BF 56.5912 74.2676 102.9083


[Lens group data]
Group Start surface Focal length
G1 1 292.39
G2 7 -45.68
G3 14 68.63
G4 29 46.12
G5 34 -63.18
G2a 7 -386.20
G2b 9 -53.05

Numerical example 2
Unit: mm
[Surface data]
Surface number rd nd vd
1 470.0448 3.0000 1.80611 40.73
2 197.1039 2.1733
3 224.0673 9.9345 1.43700 95.10
4 -481.8622 0.1500
5 146.2879 10.2750 1.43700 95.10
6 3490.0146 (d6)
7 -771.9619 1.2000 1.48749 70.44
8 250.0604 7.8524
9 -257.4717 0.8000 1.69680 55.46
10 71.7759 3.2150
11 -70.6546 0.8000 1.69680 55.46
12 70.6546 3.1825 1.84666 23.78
13 -539.2856 (d13)
14 96.7403 3.2409 1.80610 33.27
15 -295.4003 0.1500
16 64.4066 3.4504 1.58913 61.25
17 653.8902 0.6964
18 52.0811 6.7751 1.49700 81.61
19 -88.3845 1.0000 1.80610 33.27
20 188.1399 4.1142 1.49700 81.61
21 -143.6178 1.7326
22 34.6483 4.7315 1.58144 40.89
23 -1279.6230 0.9000 1.91082 35.25
24 29.3759 3.4077
25 -59.5729 0.9000 2.00100 29.13
26 178.5135 2.4049 1.62004 36.30
27 -92.8394 2.0000
28 (Aperture) ∞ (d28)
29 80.0813 3.3996 1.64769 33.84
30 -61.1308 0.1500
31 36.6430 4.3044 1.48749 70.44
32 -59.1309 0.9000 1.95375 32.32
33 266.9103 (d33)
34 65.5638 0.8000 1.84666 23.78
35 25.3459 4.7233
36 358.1214 2.4992 1.69895 30.05
37 -55.4389 0.8000 1.72916 54.67
38 339.8716 2.2270
39 -33.9872 2.0000 1.49700 81.61
40 33.9872 5.7470 1.72342 37.99
41 -66.8780 (BF)
Image plane ∞


[Various data]
Zoom ratio 3.77
Wide angle Medium telephoto Focal length 154.81 269.95 583.76
F number 5.03 5.82 6.49
Full angle of view 2ω 15.73 9.04 4.18
Image height Y 21.63 21.63 21.63
Total lens length 327.18 370.61 417.81


[Variable interval data]
Wide angle Medium telephoto
d6 99.5129 142.9445 190.1424
d13 29.8554 18.8172 3.5000
d28 24.6495 19.0107 13.9148
d33 11.3249 9.9932 2.0000
BF 56.2009 74.2096 102.6160


[Lens group data]
Group Start surface Focal length
G1 1 295.62
G2 7 -45.90
G3 14 67.64
G4 29 46.72
G5 34 -63.03
G2a 7 -387.30
G2b 9 -53.31

Numerical example 3
Unit: mm
[Surface data]
Surface number rd nd vd
1 669.3235 3.0000 1.80611 40.73
2 212.9535 2.3719
3 254.4835 9.4211 1.49700 81.61
4 -553.1367 0.1500
5 149.0820 11.3382 1.43700 95.10
6 -18619.0506 (d6)
7 116.5577 8.4891 1.51680 64.20
8 3702.0555 30.2804
9 -418.1736 1.2000 1.65844 50.85
10 93.1948 4.2586
11 -156.7544 1.0000 1.69680 55.46
12 43.0795 3.0944 1.84666 23.78
13 95.9053 3.2357
14 -69.7580 1.0000 1.72916 54.67
15 -488.0709 (d15)
16 230.4409 3.8295 1.59349 67.00
17 -117.3821 0.1500
18 74.3374 4.2031 1.59282 68.62
19 -555.7421 0.1500
20 52.7873 5.9220 1.49700 81.61
21 -207.3663 1.0000 1.88100 40.14
22 192.7502 16.6624
23 57.7314 5.2538 1.58913 61.25
24 -289.2285 2.5000 1.88100 40.14
25 38.6019 3.4883
26 (Aperture) ∞ (d26)
27 50.1360 3.4936 1.60342 38.01
28 -84.6676 0.1500
29 40.2473 3.7776 1.51742 52.15
30 -76.0898 1.0000 1.95375 32.32
31 98.3899 2.0171
32 98.5144 1.0000 2.00100 29.13
33 34.3000 16.7622
34 -50.8248 1.0000 1.49700 81.61
35 45.0635 4.8877 1.69895 30.05
36 -85.7479 (BF)
Image plane ∞


[Various data]
Zoom ratio 3.81
Wide angle Medium telephoto Focal length 153.63 270.03 584.96
F number 4.78 5.72 6.52
Full angle of view 2ω 15.79 9.01 4.17
Image height Y 21.63 21.63 21.63
Total lens length 318.17 359.70 406.77


[Variable interval data]
Wide angle Medium telephoto
d6 43.8964 85.4262 132.4974
d15 47.1598 30.9953 5.0000
d26 16.9147 10.0000 25.6742
BF 54.1136 77.1928 87.5134


[Lens group data]
Group Start surface Focal length
G1 1 305.74
G2 7 -51.23
G3 16 62.57
G4 27 221.11
G2a 7 -334.66
G2b 11 -52.39
G4a 27 56.12
G4b 32 -70.12

Numerical example 4
Unit: mm
[Surface data]
Surface number rd nd vd
1 658.2373 3.0000 1.80611 40.73
2 212.2711 2.3437
3 252.0486 9.3905 1.49700 81.61
4 -572.8397 0.1500
5 149.8902 11.2659 1.43700 95.10
6 -21938.2447 (d6)
7 118.8124 8.0467 1.51680 64.20
8 9413.4438 30.1451
9 -724.6133 1.2000 1.65844 50.85
10 106.6999 4.1242
11 -191.7662 1.0000 1.69680 55.46
12 39.9337 3.0809 1.84666 23.78
13 79.0462 3.6807
14 -63.0037 1.0000 1.72916 54.67
15 -379.3249 (d15)
16 239.4881 3.8141 1.59349 67.00
17 -117.5575 0.1500
18 73.7202 4.2489 1.59282 68.62
19 -526.2145 0.1500
20 53.1861 6.2329 1.49700 81.61
21 -204.5635 1.0000 1.88100 40.14
22 193.8410 16.4575
23 57.2372 5.2872 1.58913 61.25
24 -262.7930 2.5000 1.88100 40.14
25 38.6284 3.4894
26 (Aperture) ∞ (d26)
27 50.8908 3.4889 1.60342 38.01
28 -85.0728 0.1500
29 40.0284 3.7984 1.51742 52.15
30 -77.7319 1.0000 1.95375 32.32
31 99.7231 2.0000
32 96.7061 1.0000 2.00100 29.13
33 34.0727 16.5788
34 -50.6525 1.0000 1.49700 81.61
35 44.4999 4.9080 1.69895 30.05
36 -86.6217 (BF)
Image plane ∞


[Various data]
Zoom ratio 3.81
Wide angle Medium telephoto Focal length 153.65 270.03 584.97
F number 4.77 5.71 6.52
Full angle of view 2ω 15.78 9.01 4.17
Image height Y 21.63 21.63 21.63
Total lens length 317.42 359.69 407.23


[Variable interval data]
Wide angle Medium telephoto
d6 43.4647 85.7339 133.2753
d15 47.0863 30.9698 5.0000
d26 17.1846 10.4502 25.4857
BF 54.0057 76.8570 87.7917


[Lens group data]
Group Start surface Focal length
G1 1 308.07
G2 7 -51.57
G3 16 62.49
G4 27 219.97
G2a 7 -592.57
G2b 11 -48.48
G4a 27 55.87
G4b 32 -69.67

Numerical example 5
Unit: mm
[Surface data]
Surface number rd nd vd
1 500.3284 3.0000 1.80611 40.73
2 203.0852 2.7962
3 263.4106 8.9920 1.45860 90.19
4 -619.3383 0.1500
5 147.2402 11.1573 1.43700 95.10
6 -2565.8567 (d6)
7 116.5228 8.1048 1.51680 64.20
8 1948.9837 30.6295
9 -414.2798 1.2000 1.65844 50.85
10 86.9503 4.3441
11 -149.3142 1.0000 1.69680 55.46
12 44.3756 3.1247 1.84666 23.78
13 105.8729 3.0885
14 -71.5955 1.0000 1.72916 54.67
15 -548.7698 (d15)
16 227.5254 3.8200 1.59349 67.00
17 -119.6480 0.1500
18 72.8346 4.2498 1.59282 68.62
19 -565.5973 0.1500
20 52.8080 6.3326 1.49700 81.61
21 -212.7227 1.0000 1.88100 40.14
22 183.8575 16.3770
23 56.2162 5.3086 1.58913 61.25
24 -267.7317 2.5000 1.88100 40.14
25 38.1107 3.5058
26 (Aperture) ∞ (d26)
27 49.6333 3.5116 1.60342 38.01
28 -84.9939 0.1500
29 39.9457 3.8150 1.51742 52.15
30 -75.5093 1.0000 1.95375 32.32
31 97.6946 2.0367
32 101.4402 1.0000 2.00100 29.13
33 34.6048 16.4633
34 -50.2934 1.0000 1.49700 81.61
35 45.7728 4.8917 1.69895 30.05
36 -83.5351 (BF)
Image plane ∞


[Various data]
Zoom ratio 3.81
Wide angle Medium telephoto Focal length 153.61 270.03 584.96
F number 4.78 5.72 6.52
Full angle of view 2ω 15.79 9.01 4.17
Image height Y 21.63 21.63 21.63
Total lens length 318.85 359.91 406.28


[Variable interval data]
Wide angle Medium telephoto
d6 44.3689 85.4294 131.7960
d15 46.9680 30.8980 5.0000
d26 17.3910 10.3779 25.3074
BF 54.2750 77.3583 88.3264


[Lens group data]
Group Start surface Focal length
G1 1 302.65
G2 7 -50.72
G3 16 62.45
G4 27 214.44
G2a 7 -279.25
G2b 11 -54.18
G4a 27 55.79
G4b 32 -70.26

Numerical example 6
Unit: mm
[Surface data]
Surface number rd nd vd
1 470.6943 3.0000 1.80611 40.73
2 197.0289 4.0352
3 305.6129 9.7960 1.43700 95.10
4 -418.0350 0.1500
5 134.5620 11.3770 1.43700 95.10
6 ∞ (d6)
7 ∞ 1.2000 1.48749 70.44
8 203.4443 8.3070
9 -241.7848 0.8000 1.69680 55.46
10 69.9172 5.0046
11 -70.1700 0.8000 1.69680 55.46
12 70.1700 3.0422 1.84666 23.78
13 -596.9631 (d13)
14 87.9761 3.5038 1.80610 33.27
15 -335.1456 0.7604
16 60.1082 3.2346 1.58913 61.25
17 338.5501 0.1500
18 52.1240 6.5435 1.49700 81.61
19 -89.6446 1.0000 1.80610 33.27
20 196.9200 3.9357 1.49700 81.61
21 -143.0492 1.4245
22 34.2633 4.6758 1.58144 40.89
23 -1378.5519 0.9000 1.91082 35.25
24 28.8531 3.4881
25 -57.4563 0.9000 2.00100 29.13
26 216.0181 2.2282 1.62004 36.30
27 -106.3573 2.0000
28 (Aperture) ∞ (d28)
29 72.5306 3.4923 1.64769 33.84
30 -60.9921 0.2256
31 38.7585 4.5618 1.48749 70.44
32 -51.3029 0.9000 1.95375 32.32
33 655.5770 (d33)
34 81.2303 0.8000 1.84666 23.78
35 26.7915 4.3683
36 231.1733 2.7824 1.69895 30.05
37 -58.2211 2.7008 1.72916 54.67
38 283.2378 2.3998
39 -35.0132 1.0000 1.49700 81.61
40 35.0132 5.6228 1.72342 37.99
41 -67.1722 (BF)
Image plane ∞


[Various data]
Zoom ratio 4.66
Wide angle Medium telephoto Focal length 125.15 250.18 583.80
F number 4.86 5.84 6.50
Full angle of view 2ω 19.47 9.76 4.18
Image height Y 21.63 21.63 21.63
Total lens length 314.20 371.31 424.96


[Variable interval data]
Wide angle Medium telephoto
d6 79.8151 136.9189 190.5717
d13 33.4105 18.95 3.5013
d28 24.0103 18.6139 14.5576
d33 10.8965 10.7496 2.3209
BF 54.9618 74.9656 102.8995


[Lens group data]
Group Start surface Focal length
G1 1 292.29
G2 7 -44.57
G3 14 70.36
G4 29 44.70
G5 34 -61.99
G2a 7 -417.33
G2b 9 -51.10

[Values for conditional expressions]
Conditional expression / Example 1 2 3 4 5 6
(1) (1 / Rg21-1 / fg1) * ft 3.01 3.98 3.80 3.82 3.59 3.29
(2) β2b -0.776 -0.758 -0.765 -0.902 -0.701 -0.789
(3) fp1 / fp2 1.345 1.007 1.040 1.038 1.267 1.317

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group Gr Back lens group G2a 2a group G2b 2b group G4a 4a group G4b 4b group

Claims (5)

In order from the object side, the first lens group having a positive refractive power, the second lens group having a negative refractive power, and at least two lens groups, the rear lens having a positive refractive power as a whole over the entire zoom range. Composed of groups and
The air gap between the lens groups changes at the time of zooming,
The first lens group includes three lenses, a first negative lens, a first positive lens, and a second positive lens, which are spaced apart from each other in order from the object side.
The second lens group includes, in order from the object side, a negative refractive power group 2a and a negative refractive power group 2b.
Vibration is prevented by displacing the group 2b in a direction perpendicular to the optical axis,
A variable magnification imaging optical system having an anti-vibration function that satisfies the following conditional expression:
(1) 2.40 <(1 / Rg21-1 / fg1) * ft <4.25
(2) −0.95 <β2b <−0.65
However,
fg1: Focal length Rg21 of the first negative lens: radius of curvature of the object-side surface of the first positive lens ft: synthetic focal length β2b in the entire system at the telephoto end and infinite distance imaging state: telephoto end and infinite distance in the group 2b Imaging magnification in imaging state 2. The variable magnification imaging optical system having an image stabilization function according to claim 1, further satisfying the following conditional expression.
(3) 0.95 <fp1 / fp2 <1.55
However,
fp1: Focal length of the first positive lens fp2: Focal length of the second positive lens   3. A variable magnification imaging optical system having an image stabilization function according to claim 1, wherein the second lens group is fixed with respect to the image plane at the time of zooming.   4. A variable magnification imaging optical system having an image stabilization function according to claim 1, wherein the rear lens group includes a third lens group having a positive refractive power closest to the object side. In the rear lens group, focusing is performed using the entire lens group provided closest to the image side, or a partial lens group positioned closest to the image side among the lens groups provided closest to the image side, as a focusing lens group,
5. A variable magnification imaging optical system having an image stabilization function according to claim 1, wherein the focusing lens group as a whole has a negative refractive power.

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