JP2017032809A - Image forming optics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming optics that is less in aberration fluctuations upon focusing in an object distance over a broad range, less in aberration fluctuations upon tremor proofing, and has a high optical performance.SOLUTION: In an inner-focusing type image forming optics comprises, in order from an object side,: a first lens group G1 has positive refractive power; a second lens group G2 has negative refractive power; and a third lens group G3 has the negative refractive power, in which inner-focusing is implemented to move the second lens group, the first lens group is composed of: a 1a lens group having the positive refractive power; and a 1b lens group having the positive refractive power. The 1a lens group has at least one piece of a positive lens and negative lens, and the 1b lens group is composed of one piece of the positive lens and negative lens. The third lens group is composed of, in order from the object side,: a 3a lens group having the positive refractive power; a 3b lens group having the negative refractive power; and a 3c lens group having the positive refractive power. By moving the 3b lens group in an almost vertical direction relative to an optical lens, an image forming position is displaced, a prescribed conditional expression is satisfied.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging optical system suitable for a photographing lens used in a digital still camera, a video camera, or the like.

  Conventionally, as an imaging optical system suitable for a long focal length photographing lens, a telephoto type having a front lens group having a positive refractive power and a rear lens group having a negative refractive power in order from the object side to the image side. An imaging optical system (telephoto lens) is known.

  In recent years, in many telephoto lenses, focusing is performed by moving a part of a lens group instead of the entire imaging optical system. In particular, many inner focus telephoto lenses that perform focusing by moving a relatively lightweight lens group other than the front lens group are known.

  Further, in an imaging optical system with a long focal length, the influence of the displacement of the image position due to the tilt of the optical system due to vibration, so-called blurring of the photographed image becomes large. For this reason, a telephoto lens having a function of correcting a captured image so as not to blur (anti-vibration function) is known. Among them, many telephoto lenses that correct blurring of a captured image by moving some lens groups (anti-vibration groups) in a direction substantially perpendicular to the optical axis are known.

JP 2009-180827 A Japanese Patent No. 3486541

  In recent years, there has been a demand for an imaging optical system in which aberrations are corrected more favorably in order to increase the number of pixels in an image sensor. In addition to high optical performance, downsizing and weight reduction of the entire optical system, faster focusing, and higher vibration isolation functions are desired. In particular, downsizing and weight reduction of the focus group and image stabilization group are not only advantageous for high-speed focusing and high image stabilization function, but also can be driven by a small actuator, thereby reducing the overall size of the taking lens. It also leads to weight reduction.

  In the optical system described in Patent Document 1, the third lens group includes a 3a lens group having a positive refractive power and a 3b lens group having a negative refractive power in order from the object side. Therefore, it is anti-vibrated by moving it in a substantially vertical direction. However, since the light ray height in the vicinity of the vibration-proof group is high, the diameter of the vibration-proof group is large, and it cannot be said that miniaturization and weight reduction are sufficient. In addition, the image stabilization coefficient (ratio between the displacement of the imaging position of the captured image and the amount of movement of the image stabilization group during image stabilization) is 1.4 to 1.7. In order to reduce the size of the vibration isolation mechanism including the actuator while suppressing the above, a larger vibration isolation coefficient is desirable.

  In the optical system described in Patent Document 2, the third lens group includes, in order from the object side, a 3a lens group having a positive refractive power, a 3b lens group having a negative refractive power, and a 3c lens group having a positive refractive power. Anti-vibration is performed by moving the third lens group in a direction substantially perpendicular to the optical axis. As a result, the diameter of the vibration-proof group is reduced to reduce the size and weight. However, since the height of the light beam in the vicinity of the focus group is high, the diameter of the focus group is large, and it cannot be said that miniaturization and weight reduction are sufficient. For this reason, it is disadvantageous for speeding up the focusing, and it is also disadvantageous for downsizing of the entire photographing lens due to the enlargement of the actuator for driving.

  The present invention has been made in view of such a situation, and the entire optical system is small, and in particular, from a infinity object to a short-distance object while realizing a reduction in size and weight of a focus group and a vibration isolation group. It is an object of the present invention to provide an imaging optical system that has high optical performance with little aberration fluctuation during focusing in a wide range of object distances and little aberration fluctuation during image stabilization.

The first invention, which is a means for solving the above-mentioned problems, is, in order from the object side to the image side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a negative refractive power. In the inner-focus imaging optical system that includes the third lens group G3 and performs focusing by moving the second lens group G2 along the optical axis, the first lens group G1 is the first lens group. The first a lens group G1a having a positive refractive power and a first b lens group G1b having a positive refractive power with the widest lens interval in G1 as a boundary. The first a lens group G1a includes at least one positive lens and at least one lens. The first lens group G1b is composed of one positive lens and one negative lens, and the third lens group G3 is a 3a lens having a positive refractive power in order from the object side. Group G3a, negative refractive power The third-b lens group G3b and the third-c lens group G3c having a positive refractive power are formed into three groups. The imaging position of the photographed image is obtained by moving the third-b lens group G3b in a direction substantially perpendicular to the optical axis. Is an inner focus type imaging optical system characterized by satisfying the following conditional expression.
(1) 0.25 <f1 / f <0.60
(2) −0.60 <f2 / f <−0.15
(3) -2.50 <f3 / f <-0.25
(4) 0.15 <f3a / f <2.00
(5) -0.20 <f3b / f <-0.04
(6) 0.05 <f3c / f <0.25
However,
f: focal length of the entire optical system at infinity shooting f1: focal length of the first lens group G1 f2: focal length of the second lens group G2 f3: focal length of the third lens group G3 f3a: 3a lens group Focal length f3b of G3a: Focal length f3c of the third b lens group G3b: Focal length of the third c lens group G3c

According to a second aspect of the present invention, there is provided the imaging optical system according to the first aspect, further satisfying the following conditional expression in the first aspect.
(7) 80 <νd1ap
(8) 0.030 <θgF1ap−0.6483 + 0.0018 × νd1ap
(9) θgF1an−0.6483 + 0.0018 × νd1an <0.000
However,
νd1ap: Abbe number θgF1ap for the d-line of at least one positive lens material of the 1a lens group G1a: Portion of at least one positive lens material of the 1a lens group G1a for the g-line and F-line Dispersion ratio νd1an: Abbe number θgF1an with respect to d-line of at least one negative lens material of the 1a lens group G1a: g-line and F-line of at least one negative lens material of the 1a lens group G1a Partial dispersion ratio for

According to a third aspect of the present invention, in the first or second aspect of the invention, the following conditional expression is satisfied.
(10) 65 <νd1bp
(11) 0.015 <θgF1bp−0.6483 + 0.0018 × νd1bp
(12) θgF1bn−0.6483 + 0.0018 × νd1bn <0.000
However,
νd1bp: Abbe number θgF1bp of the material of the positive lens of the 1b lens group G1b with respect to the d line θgF1bp: Partial dispersion ratio of the material of the positive lens of the 1b lens group G1b with respect to the g line and F line νd1bn: 1b lens group Abbe number θgF1bn with respect to d-line of negative lens material of G1b: partial dispersion ratio of negative lens material of first-b lens group G1b with respect to g-line and F-line

According to a fourth invention, in any one of the first to third inventions, the second lens group includes a cemented lens in which one positive lens and one negative lens are cemented, and the following conditional expression: The imaging optical system according to any one of claims 1 to 3, wherein:
(13) D2 / LT <0.65
However,
D2: Distance from the most object side lens surface of the second lens group to the image plane at infinity LT: Distance from the most object side lens surface of the entire optical system to the image plane at infinity

  According to a fifth invention, in any one of the second to fourth inventions, the first-a lens group G1a includes two positive lenses satisfying conditional expressions (7) and (8). This is an imaging optical system.

  According to the present invention, the entire optical system is small, and in particular, the focusing group and the anti-vibration group can be reduced in size and weight, while focusing at a wide range of object distances from an infinite object to a close object. It is possible to provide an imaging optical system that has little fluctuation, little aberration fluctuation during image stabilization, and high optical performance.

It is a lens block diagram in the infinity of Example 1 of this invention. FIG. 6 is a longitudinal aberration diagram at infinity according to Example 1 of the present invention. FIG. 6 is a longitudinal aberration diagram at an imaging distance of 3500 mm in Example 1 of the present invention. FIG. 6 is a lateral aberration diagram at infinity according to Example 1 of the present invention. FIG. 5 is a lateral aberration diagram at an imaging distance of 3500 mm in Example 1 of the present invention. It is a lateral aberration diagram at the time of 0.25 ° vibration isolation at infinity according to Example 1 of the present invention. It is a lens block diagram in the infinity of Example 2 of this invention. It is a longitudinal aberration diagram at infinity of Example 2 of the present invention. FIG. 6 is a longitudinal aberration diagram at an imaging distance of 4500 mm in Example 2 of the present invention. It is a lateral aberration diagram at infinity of Example 2 of the present invention. FIG. 6 is a lateral aberration diagram at an imaging distance of 4500 mm in Example 2 of the present invention. It is a lateral aberration diagram at the time of 0.25 ° vibration isolation at infinity according to Example 2 of the present invention. It is a lens block diagram in the infinity of Example 3 of this invention. It is a longitudinal aberration diagram at infinity of Example 3 of the present invention. FIG. 6 is a longitudinal aberration diagram at an imaging distance of 6000 mm in Example 3 of the present invention. It is a lateral aberration diagram at infinity of Example 3 of the present invention. FIG. 6 is a lateral aberration diagram at an imaging distance of 6000 mm in Example 3 of the present invention. It is a lateral aberration diagram at the time of 0.2 ° vibration isolation at infinity in Example 3 of the present invention. It is a lens block diagram in the infinity of Example 4 of this invention. It is a longitudinal aberration figure of Example 4 of the present invention at infinity. FIG. 6 is a longitudinal aberration diagram at an imaging distance of 6000 mm in Example 4 of the present invention. It is a lateral aberration figure in the infinity of Example 4 of this invention. FIG. 6 is a lateral aberration diagram at an imaging distance of 6000 mm in Example 4 of the present invention. It is a lateral aberration figure at the time of 0.2 degree anti-vibration in the infinity of Example 4 of this invention. It is a lens block diagram in the infinity of Example 5 of this invention. It is a longitudinal aberration diagram at infinity of Example 5 of the present invention. FIG. 6 is a longitudinal aberration diagram at an imaging distance of 3500 mm in Example 5 of the present invention. It is a lateral aberration figure in infinity of Example 5 of this invention. FIG. 10 is a lateral aberration diagram at an imaging distance of 3500 mm in Example 5 of the present invention. It is a lateral aberration diagram at the time of 0.25 ° vibration isolation at infinity in Example 5 of the present invention. It is a lens block diagram in the infinity of Example 6 of this invention. It is a longitudinal aberration figure in the infinity of Example 6 of this invention. It is a longitudinal aberration figure in imaging distance 3500mm of Example 6 of this invention. It is a lateral aberration diagram at infinity in Example 6 of the present invention. It is a lateral aberration diagram at the shooting distance of 3500 mm in Example 6 of the present invention. It is a lateral aberration diagram at the time of 0.25 ° vibration isolation at infinity in Example 6 of the present invention.

  As can be seen from the lens configuration diagrams shown in FIGS. 1, 7, 13, 19, 25, and 31, the imaging optical system according to the present invention includes a first lens group G1 having a positive refractive power in order from the object side to the image side. The second lens group G2 having a negative refractive power, an aperture stop S, and a third lens group G3 having a negative refractive power, and moves the second lens group G2 to the image plane side along the optical axis. Thus, focusing from an infinite object to a close object is performed.

  The first lens group G1 includes a first-a lens group G1a having a positive refractive power and a first-b lens group G1b having a positive refractive power at the widest lens interval in the first lens group G1, and the first-a lens group. G1a has at least one positive lens and at least one negative lens, and the first b lens group G1b is composed of one positive lens and one negative lens.

  The third lens group G3 is composed of three groups in order from the object side: a third a lens group G3a having a positive refractive power, a third b lens group G3b having a negative refractive power, and a third c lens group G3c having a positive refractive power. The imaging position of the photographed image is displaced by moving the third lens group G3b in a direction substantially perpendicular to the optical axis.

  In the imaging optical system of the present invention, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a negative refractive power are arranged in order from the object side to the image side. doing. This is a telephoto type configuration including a first lens group G1 having a positive refractive power and a rear lens group having a negative refractive power, and prevents the total length of the optical system from being increased with respect to the focal length.

  In the imaging optical system of the present invention, focusing is performed by moving the second lens group G2 having negative refractive power. Since the luminous flux is converged by the positive first lens group G1, the second lens group G2 has a small lens diameter and is light with respect to the first lens group G1, so that it can be driven by a small actuator.

  In the imaging optical system of the present invention, the third lens group G3 having a negative refractive power is arranged, and the negative refractive power of the telephoto type rear lens group is shared with the second lens group G2, The lateral magnification of the second lens group G2 is reduced while suppressing an increase in the total length of the optical system. If the focal length of the second lens group G2 is the same, reducing the lateral magnification of the second lens group G2 increases the distance between the principal points of the first lens group G1 and the second lens group G2, that is, the second lens group. This means that the position of G2 is brought close to the image plane. By disposing the second lens group G2 closer to the image plane with a low light beam height, the focus group can be further reduced in size and weight.

  The first lens group G1 is composed of a first a lens group G1a having a positive refractive power and a first b lens group G1b having a positive refractive power at the widest lens interval in the first lens group G1, and the two lens groups are positive. By sharing the refractive power, the occurrence of various aberrations including spherical aberration is suppressed while having a strong convergence effect.

  The first-a lens group G1a has at least one positive lens and at least one negative lens, and the first-b lens group G1b is composed of one positive lens and one negative lens. And other aberrations are reduced. The 1b lens group G1b has a role of canceling fluctuations of various aberrations including spherical aberration in the 1a lens group G1a and the second lens group G2 during focusing.

  The third lens group G3 includes, in order from the object side, a three-group lens group G3a having a positive refractive power, a third-b lens group G3b having a negative refractive power, and a third-c lens group G3c having a positive refractive power. In addition to the anti-vibration function, it also plays a role of correcting various aberrations remaining in the first lens group G1 and the second lens group G2.

  By converging the light beam with the 3a lens group G3a having a positive refractive power, it is possible to reduce the lens diameter of the 3b lens group G3b that moves during image stabilization. Furthermore, by disposing the third c lens group G3c having a positive refractive power, it becomes possible to increase the negative refractive power of the third b lens group G3b while maintaining the focal length of the entire optical system, and the third b lens group G3b. Thus, the image formation position of the captured image can be greatly displaced with a small amount of movement.

Furthermore, the imaging optical system of the present invention satisfies the following conditional expression.
(1) 0.25 <f1 / f <0.60
(2) −0.60 <f2 / f <−0.15
(3) -2.50 <f3 / f <-0.25
(4) 0.15 <f3a / f <2.00
(5) -0.20 <f3b / f <-0.04
(6) 0.05 <f3c / f <0.25
However,
f: focal length of the entire optical system at infinity shooting f1: focal length of the first lens group G1 f2: focal length of the second lens group G2 f3: focal length of the third lens group G3 f3a: 3a lens group Focal length f3b of G3a: Focal length f3c of the third b lens group G3b: Focal length of the third c lens group G3c

  Conditional expression (1) defines a preferable range for the ratio between the focal length of the first lens group G1 and the focal length of the entire optical system.

  When the upper limit of conditional expression (1) is exceeded and the positive refractive power of the first lens group G1 becomes too weak, the effect of shortening the total length of the optical system by the telephoto type configuration is weakened, and the entire optical system is downsized. It becomes difficult. Further, the height of the light beam incident on the second lens group G2 cannot be sufficiently converged, and the increase in the weight of the focus group is disadvantageous for high-speed focusing, and a large actuator is required for driving. It is also difficult to downsize the entire taking lens. On the other hand, if the positive refractive power of the first lens group G1 becomes too strong beyond the lower limit value of the conditional expression (1), it is advantageous for downsizing the imaging optical system, but it occurs in the first lens group G1. The amount of spherical aberration and axial chromatic aberration that increases is difficult to correct.

  Regarding conditional expression (1), the lower limit value is desirably limited to 0.30 and the upper limit value is preferably limited to 0.55, whereby the above-described effect can be further ensured.

  Conditional expression (2) defines a preferable range for the ratio between the focal length of the second lens group G2 and the focal length of the entire optical system.

  If the negative refracting power of the second lens group G2 exceeds the upper limit of the conditional expression (2) and becomes too strong, axial chromatic aberration and lateral chromatic aberration during focusing will increase greatly, and good performance will be achieved over a wide focusing range. It becomes difficult to obtain. On the other hand, if the negative refractive power of the second lens group G2 becomes too weak beyond the lower limit value of the conditional expression (2), the amount of movement of the second lens group G2 during focusing increases, and the entire optical system becomes small. It becomes difficult.

  Regarding conditional expression (2), the lower limit value is desirably limited to -0.55, and the upper limit value is desirably limited to -0.20, whereby the above-described effects can be further ensured.

  Conditional expression (3) defines a preferable range for the ratio between the focal length of the third lens group G3 and the focal length of the entire optical system.

  If the negative refracting power of the third lens group G3 exceeds the upper limit of the conditional expression (3) and becomes too strong, the positive refracting power of the first lens group G1 is increased in order to maintain the focal length of the entire optical system. It is necessary to increase the intensity or to decrease the negative refractive power of the second lens group G2. If the positive refractive power of the first lens group G1 becomes too strong, as described above, the amount of spherical aberration and axial chromatic aberration generated in the first lens group G1 becomes large, and correction thereof becomes difficult. If the negative refractive power of the second lens group G2 becomes too weak, the amount of movement of the second lens group G2 during focusing increases as described above, and it becomes difficult to reduce the size of the entire optical system.

  On the other hand, if the negative refractive power of the third lens group G3 becomes too weak beyond the lower limit value of the conditional expression (3), the lateral magnification of the second lens group G2 is set to prevent the overall length of the optical system from becoming too long. It needs to be bigger. If the negative refracting power of the second lens group G2 is increased to increase the lateral magnification, axial chromatic aberration and lateral chromatic aberration during focusing increase greatly, making it difficult to obtain good performance in a wide focusing range. Become. In order to increase the lateral magnification without changing the negative refractive power of the second lens group G2, it is necessary to reduce the distance between the principal points of the first lens group G1 and the second lens group G2. In this case, the height of the light beam in the second lens group G2 increases, which increases the weight of the focus group, which is disadvantageous for high-speed focusing, and requires a large actuator for driving. It becomes difficult.

  For conditional expression (3), the lower limit value is desirably limited to -2.0, and the upper limit value is desirably limited to -0.30, whereby the above-described effect can be further ensured.

  Conditional expressions (4) to (6) indicate the focal lengths and optical systems of the respective lens groups included in the third lens group G3 in order to obtain good performance even during image stabilization while ensuring a sufficiently large image stabilization coefficient. A preferred range is defined for the ratio to the focal length of the entire system.

  If the positive refractive power of the 3a lens group G3a becomes too weak beyond the upper limit value of the conditional expression (4), the light incident on the 3b lens group G3b cannot be sufficiently converged, and the vibration-proof group is small and lightweight. It becomes difficult.

  On the other hand, if the positive refractive power of the 3a lens group G3a becomes too strong beyond the lower limit value of the conditional expression (4), in order to obtain a sufficiently large image stabilization coefficient and good performance during image stabilization, It is necessary to weaken the negative refractive power of the three lens group G3. If the negative refractive power of the third lens group G3 becomes too weak, it is necessary to increase the lateral magnification of the second lens group G2 in order to suppress an increase in the overall length of the optical system as described above. If the negative refracting power of the second lens group G2 is increased to increase the lateral magnification, axial chromatic aberration and lateral chromatic aberration during focusing increase greatly, making it difficult to obtain good performance in a wide focusing range. Become. In order to increase the lateral magnification without changing the negative refractive power of the second lens group G2, it is necessary to reduce the distance between the principal points of the first lens group G1 and the second lens group G2. In this case, the height of the light beam in the second lens group G2 increases, which increases the weight of the focus group, which is disadvantageous for high-speed focusing, and requires a large actuator for driving. It becomes difficult.

  Regarding conditional expression (4), the lower limit value is desirably limited to 0.20 and the upper limit value is desirably limited to 1.50.

  If the upper limit of conditional expression (5) is exceeded and the negative refractive power of the third lens group G3b becomes too strong, the image stabilization coefficient increases, and the imaging position of the captured image can be greatly displaced with a small amount of movement. However, fluctuations in coma and astigmatism when the image stabilizing group moves in a direction substantially perpendicular to the optical axis becomes large, and it is difficult to obtain good performance during image stabilization. On the other hand, if the negative refractive power of the third lens group G3b becomes too weak beyond the lower limit value of the conditional expression (5), the image stabilization coefficient becomes small, and the anti-shake necessary for displacing the imaging position of the photographed image is required. The amount of movement of the tremor group increases. As a result, the diameter of the actuator that drives the image stabilizing group increases, making it difficult to reduce the size of the entire taking lens.

  Regarding conditional expression (5), the lower limit value is desirably limited to -0.15, and the upper limit value is desirably limited to -0.05, whereby the above-described effect can be further ensured.

  When the upper limit of conditional expression (6) is exceeded and the positive refractive power of the third c lens group G3c becomes too weak, the image stabilization coefficient decreases, and the image stabilization group necessary for displacing the imaging position of the captured image. The amount of movement increases. As a result, the diameter of the actuator that drives the image stabilizing group increases, making it difficult to reduce the size of the entire taking lens. On the other hand, if the positive refractive power of the third c lens group G3c becomes too strong beyond the lower limit value of the conditional expression (6), the image stabilization coefficient increases, and the imaging position of the captured image is greatly displaced with a small amount of movement. However, fluctuations in coma and astigmatism when the image stabilizing group moves in a direction substantially perpendicular to the optical axis increases, making it difficult to obtain good performance during image stabilization.

  Regarding conditional expression (6), the lower limit value is desirably limited to 0.08 and the upper limit value is preferably limited to 0.20, whereby the above-described effect can be further ensured.

Furthermore, in the imaging optical system of the present invention, it is desirable that the following conditional expression is satisfied.
(7) 80 <νd1ap
(8) 0.030 <θgF1ap−0.6483 + 0.0018 × νd1ap
(9) θgF1an−0.6483 + 0.0018 × νd1an <0.000
However,
νd1ap: Abbe number θgF1ap for the d-line of at least one positive lens material of the 1a lens group G1a: Portion of at least one positive lens material of the 1a lens group G1a for the g-line and F-line Dispersion ratio νd1an: Abbe number θgF1an with respect to d-line of at least one negative lens material of the 1a lens group G1a: g-line and F-line of at least one negative lens material of the 1a lens group G1a In addition, the refractive index with respect to g-line (wavelength 435.8 nm), F-line (wavelength 486.1 nm), d-line (wavelength 587.6 nm), and C-line (wavelength 656.3 nm) is ng, When nF, nd, and nC, the Abbe number νd and the partial dispersion ratio θgF are expressed by the following equations.
νd = (nd−1) / (nF−nC)
θgF = (ng−nF) / (nF−nC)

  Conditional expressions (7), (8), and (9) are for the material of at least one positive lens included in the 1a lens group G1a and at least one negative lens included in the 1a lens group G1a. The optical characteristics are defined in order to satisfactorily correct axial chromatic aberration and lateral chromatic aberration including the spectrum.

  In general, in order to satisfactorily correct chromatic aberration including the secondary spectrum, it is preferable to combine a positive lens and a negative lens that have a large Abbe number difference and a small partial dispersion ratio difference. However, as long as a general optical material is used, there is no material having a large Abbe number difference while having a substantially equal partial dispersion ratio. In the imaging optical system of the present invention, the first lens group G1a has at least one positive lens made of a material having low dispersion and high anomalous dispersion (a large partial dispersion ratio compared to a normal material), and at least one By having at least one negative lens made of a material having a higher dispersion and lower anomalous dispersion (a partial dispersion ratio is smaller than that of a normal material) than a single positive lens, the first lens group G1a has Chromatic aberration including the generated secondary spectrum is suppressed.

  When the lower limit of conditional expression (7) is exceeded and the Abbe number of at least one positive lens is decreased, it becomes difficult to increase the Abbe number difference between the positive lens and the negative lens, and it becomes difficult to correct chromatic aberration.

  Regarding conditional expression (7), the lower limit value is desirably limited to 90, so that the above-described effect can be further ensured.

  If the lower limit of conditional expression (8) is exceeded and the anomalous dispersion of at least one positive lens is reduced, it becomes difficult to reduce the difference in partial dispersion ratio between the positive lens and the negative lens, and chromatic aberration, particularly the secondary spectrum. Correction becomes difficult.

  Regarding conditional expression (8), the lower limit is desirably limited to 0.040, so that the above-described effect can be made more reliable.

  If the anomalous dispersion of at least one negative lens exceeds the upper limit of conditional expression (9), it becomes difficult to reduce the difference in partial dispersion ratio between the positive lens and the negative lens, and chromatic aberration, particularly the secondary spectrum. Correction becomes difficult.

  Regarding conditional expression (9), the above-mentioned effect can be made more reliable by desirably limiting the upper limit to −0.006.

Furthermore, in the imaging optical system of the present invention, it is desirable that the following conditional expression is satisfied.
(10) 65 <νd1bp
(11) 0.015 <θgF1bp−0.6483 + 0.0018 × νd1bp
(12) θgF1bn−0.6483 + 0.0018 × νd1bn <0.000
However,
νd1bp: Abbe number θgF1bp of the material of the positive lens of the 1b lens group G1b with respect to the d line θgF1bp: Partial dispersion ratio of the material of the positive lens of the 1b lens group G1b with respect to the g line and F line νd1bn: 1b lens group Abbe number θgF1bn with respect to d-line of negative lens material of G1b: partial dispersion ratio of negative lens material of first-b lens group G1b with respect to g-line and F-line

  Conditional expressions (10), (11), and (12) are axial chromatic aberration including the secondary spectrum for the positive lens material included in the 1b lens group G1b and the negative lens material included in the 1b lens group G1b. In order to satisfactorily correct lateral chromatic aberration, a preferable optical characteristic is defined.

  As described above, in order to satisfactorily correct chromatic aberration including the secondary spectrum, it is preferable to combine a positive lens and a negative lens that have a large Abbe number difference and a small partial dispersion ratio difference. However, as long as a general optical material is used, there is no material having a large Abbe number difference while having a substantially equal partial dispersion ratio. In the imaging optical system of the present invention, the first lens group G1b is a positive lens made of a material having low dispersion and high anomalous dispersion (a large partial dispersion ratio compared to a normal material), and a higher dispersion than the positive lens. And a negative lens made of a material having low anomalous dispersion (partial dispersion ratio is smaller than that of a normal material), thereby suppressing chromatic aberration including a secondary spectrum generated in the 1b lens group G1b. ing.

  When the lower limit of conditional expression (10) is exceeded and the Abbe number of the positive lens decreases, it becomes difficult to increase the Abbe number difference between the positive lens and the negative lens, and correction of chromatic aberration becomes difficult.

  Regarding conditional expression (10), the lower limit value is desirably limited to 68, so that the above-described effect can be made more reliable.

  If the lower limit of conditional expression (11) is exceeded and the anomalous dispersion of the positive lens becomes lower, it becomes difficult to reduce the difference in partial dispersion ratio between the positive lens and the negative lens, making it difficult to correct chromatic aberration, particularly the secondary spectrum. Become.

  For conditional expression (11), the lower limit is desirably limited to 0.018, so that the above-described effect can be made more reliable.

  If the upper limit of conditional expression (12) is exceeded and the anomalous dispersion of the negative lens increases, it becomes difficult to reduce the difference in partial dispersion ratio between the positive lens and the negative lens, making it difficult to correct chromatic aberration, particularly the secondary spectrum. Become.

  Regarding conditional expression (12), the above-mentioned effect can be made more reliable by desirably limiting the upper limit value to -0.004.

  Furthermore, in the imaging optical system of the present invention, it is desirable that the second lens group is composed of a cemented lens in which one positive lens and one negative lens are cemented. With this configuration, it is possible to obtain a favorable performance in a wide focusing range by reducing the variation in longitudinal chromatic aberration during focusing while reducing the weight of the focus group.

Moreover, it is desirable to satisfy the following conditional expressions.
(13) D2 / LT <0.65
However,
D2: Distance from the most object side lens surface of the second lens group to the image plane at infinity LT: Distance from the most object side lens surface of the entire optical system to the image plane at infinity

  Conditional expression (13) relates to the position of the second lens group G2 on the optical axis, and defines a preferable arrangement for reducing the diameter of the second lens group G2 and reducing the weight.

  If the upper limit of conditional expression (13) is exceeded and the distance from the lens surface closest to the object side of the second lens group G2 to the image plane becomes too large, the beam height increases and the diameter of the second lens group G2 increases. The weight also increases. Therefore, an increase in the weight of the focus group is disadvantageous for high-speed focusing, and a large actuator is required for driving, so that it is difficult to reduce the size of the entire photographing lens.

  Regarding conditional expression (13), the above-mentioned effect can be made more reliable by desirably limiting the upper limit to 0.60.

  Furthermore, in the imaging optical system of the present invention, it is desirable that the first-a lens group G1a has two positive lenses that satisfy the conditional expression (7) and the conditional expression (8). By having two positive lenses, various aberrations including spherical aberration occurring in the 1a lens group G1a can be corrected more satisfactorily. In addition, since the two positive lenses satisfy the conditional expressions (7) and (8), it is possible to correct axial chromatic aberration and lateral chromatic aberration better including the secondary spectrum.

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

  In the imaging optical system of the present invention, it is desirable that the third lens group G3b is composed of one positive lens and two negative lenses. With this configuration, it is possible to achieve a high anti-vibration coefficient while suppressing an increase in the weight of the anti-vibration group, and to sufficiently suppress variations in various aberrations such as chromatic aberration, coma, and astigmatism during image stabilization. Become.

  Furthermore, in the imaging optical system of the present invention, it is desirable that the third c lens group G3c has at least one negative lens and a plurality of positive lenses. With this configuration, it is possible to increase the positive refractive power of the third c lens group G3c and obtain a high image stabilization coefficient while suppressing various aberrations such as spherical aberration and chromatic aberration that occur in the third c lens group G3c.

  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 to the image side, the lens unit includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a negative refractive power.

  The first lens group G1 includes a first-a lens group G1a having a positive refractive power and a first-b lens group G1b having a positive refractive power. The first-a lens group G1a includes a biconvex positive lens L1, a negative meniscus lens L2 having a convex surface facing the image side, and a biconvex positive lens L3. The first-b lens group G1b includes a cemented lens including two lenses, a negative meniscus lens L4 having a convex surface facing the object side and a positive meniscus lens L5 having a convex surface facing the object side.

  The second lens group G2 includes a cemented lens including two lenses, a biconvex positive lens L6 and a biconcave negative lens L7. The second lens group G2 is arranged on the image plane side along the optical axis. Focusing from an infinite object to a close object is performed.

  The aperture stop S is disposed between the second lens group G2 and the third lens group G3.

  The third lens group G3 is composed of three groups: a 3a lens group G3a having a positive refractive power, a 3b lens group G3b having a negative refractive power, and a third c lens group G3c having a positive refractive power. The third-b lens group G3b is moved in a direction substantially perpendicular to the optical axis to displace the imaging position of the captured image.

  The third-a lens group G3a includes a cemented lens including two lenses, a biconvex positive lens L8 and a negative meniscus lens L9 having a convex surface facing the image side. The third lens group G3b includes a cemented lens including two lenses, a biconvex positive lens L10 and a biconcave negative lens L11, and a biconcave negative lens L12. The third c lens group G3c includes a biconvex positive lens L13, and a cemented lens including two lenses, a biconvex positive lens L14 and a biconcave negative lens L15.

  The optical filter FL is disposed between the third lens group G3 and the image plane I.

  FIG. 7 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 to the image side, the lens unit includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a negative refractive power.

  The first lens group G1 includes a first-a lens group G1a having a positive refractive power and a first-b lens group G1b having a positive refractive power. The first-a lens group G1a includes a biconvex positive lens L1, a negative meniscus lens L2 having a convex surface facing the image side, and a biconvex positive lens L3. The first-b lens group G1b includes a cemented lens including two lenses, a negative meniscus lens L4 having a convex surface facing the object side and a positive meniscus lens L5 having a convex surface facing the object side.

  The second lens group G2 includes a cemented lens including two lenses, a biconvex positive lens L6 and a biconcave negative lens L7. The second lens group G2 is arranged on the image plane side along the optical axis. Focusing from an infinite object to a close object is performed.

  The aperture stop S is disposed between the second lens group G2 and the third lens group G3.

  The third lens group G3 is composed of three groups: a 3a lens group G3a having a positive refractive power, a 3b lens group G3b having a negative refractive power, and a third c lens group G3c having a positive refractive power. The third-b lens group G3b is moved in a direction substantially perpendicular to the optical axis to displace the imaging position of the captured image.

  The third-a lens group G3a includes a cemented lens including two lenses, a biconvex positive lens L8 and a negative meniscus lens L9 having a convex surface facing the image side. The third lens group G3b includes a cemented lens including two lenses, a biconvex positive lens L10 and a biconcave negative lens L11, and a biconcave negative lens L12. The third c lens group G3c includes a biconvex positive lens L13, and a cemented lens including two lenses, a biconvex positive lens L14 and a biconcave negative lens L15.

  The optical filter FL is disposed between the third lens group G3 and the image plane I.

  FIG. 13 is a lens configuration diagram of the imaging optical system according to Example 3 of the present invention. In order from the object side to the image side, the lens unit includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a negative refractive power.

  The first lens group G1 includes a first-a lens group G1a having a positive refractive power and a first-b lens group G1b having a positive refractive power. The first-a lens group G1a includes a biconvex positive lens L1, a negative meniscus lens L2 having a convex surface facing the image side, and a biconvex positive lens L3. The first-b lens group G1b includes a cemented lens including two lenses, a negative meniscus lens L4 having a convex surface facing the object side and a positive meniscus lens L5 having a convex surface facing the object side.

  The second lens group G2 includes a cemented lens including two lenses, a biconvex positive lens L6 and a biconcave negative lens L7. The second lens group G2 is arranged on the image plane side along the optical axis. Focusing from an infinite object to a close object is performed.

  The aperture stop S is disposed between the second lens group G2 and the third lens group G3.

  The third lens group G3 is composed of three groups: a 3a lens group G3a having a positive refractive power, a 3b lens group G3b having a negative refractive power, and a third c lens group G3c having a positive refractive power. The third-b lens group G3b is moved in a direction substantially perpendicular to the optical axis to displace the imaging position of the captured image.

  The third-a lens group G3a includes a cemented lens including two lenses, a positive meniscus lens L8 having a convex surface facing the image side and a negative meniscus lens L9 having a convex surface facing the image side. The third lens group G3b includes a cemented lens including two lenses, a biconvex positive lens L10 and a biconcave negative lens L11, and a biconcave negative lens L12. The third c lens group G3c has a biconvex positive lens L13, a cemented lens composed of two lenses, a biconvex positive lens L14 and a biconcave negative lens L15, and a convex surface facing the image side. It is composed of a cemented lens including two lenses, a positive meniscus lens L16 and a negative meniscus lens L17 having a convex surface facing the image side.

  The optical filter FL is disposed between the third lens group G3 and the image plane I.

  FIG. 19 is a lens configuration diagram of the imaging optical system according to Example 4 of the present invention. In order from the object side to the image side, the lens unit includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a negative refractive power.

  The first lens group G1 includes a first-a lens group G1a having a positive refractive power and a first-b lens group G1b having a positive refractive power. The first-a lens group G1a includes a biconvex positive lens L1, a negative meniscus lens L2 having a convex surface facing the image side, and a biconvex positive lens L3. The first-b lens group G1b includes a cemented lens including two lenses, a negative meniscus lens L4 having a convex surface facing the object side and a positive meniscus lens L5 having a convex surface facing the object side.

  The second lens group G2 includes a cemented lens including two lenses, a biconvex positive lens L6 and a biconcave negative lens L7. The second lens group G2 is arranged on the image plane side along the optical axis. Focusing from an infinite object to a close object is performed.

  The aperture stop S is disposed between the second lens group G2 and the third lens group G3.

  The third lens group G3 is composed of three groups: a 3a lens group G3a having a positive refractive power, a 3b lens group G3b having a negative refractive power, and a third c lens group G3c having a positive refractive power. The third-b lens group G3b is moved in a direction substantially perpendicular to the optical axis to displace the imaging position of the captured image.

  The third-a lens group G3a includes a cemented lens including two lenses, a positive meniscus lens L8 having a convex surface facing the image side and a negative meniscus lens L9 having a convex surface facing the image side. The third lens group G3b includes a cemented lens including two lenses, a biconvex positive lens L10 and a biconcave negative lens L11, and a biconcave negative lens L12. The third c lens group G3c includes a cemented lens composed of two lenses, a biconvex positive lens L13, a biconvex positive lens L14, and a negative meniscus lens L15 having a convex surface facing the image side, and an image side. It is composed of a cemented lens composed of two lenses, a positive meniscus lens L16 having a convex surface and a negative meniscus lens L17 having a convex surface facing the image.

  The optical filter FL is disposed between the third lens group G3 and the image plane I.

  FIG. 25 is a lens configuration diagram of the imaging optical system according to Example 5 of the present invention. In order from the object side to the image side, the lens unit includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a negative refractive power.

  The first lens group G1 includes a first-a lens group G1a having a positive refractive power and a first-b lens group G1b having a positive refractive power. The first-a lens group G1a includes a biconvex positive lens L1, a negative meniscus lens L2 having a convex surface facing the image side, and a biconvex positive lens L3. The first-b lens group G1b includes a cemented lens including two lenses, a negative meniscus lens L4 having a convex surface facing the object side and a positive meniscus lens L5 having a convex surface facing the object side.

  The second lens group G2 includes a cemented lens including two lenses, a biconvex positive lens L6 and a biconcave negative lens L7. The second lens group G2 is arranged on the image plane side along the optical axis. Focusing from an infinite object to a close object is performed.

  The aperture stop S is disposed between the second lens group G2 and the third lens group G3.

  The third lens group G3 is composed of three groups: a 3a lens group G3a having a positive refractive power, a 3b lens group G3b having a negative refractive power, and a third c lens group G3c having a positive refractive power. The third-b lens group G3b is moved in a direction substantially perpendicular to the optical axis to displace the imaging position of the captured image.

  The third-a lens group G3a includes a cemented lens including two lenses, a positive meniscus lens L8 having a convex surface facing the image side and a negative meniscus lens L9 having a convex surface facing the image side. The third lens group G3b includes a cemented lens including two lenses, a biconvex positive lens L10 and a biconcave negative lens L11, and a biconcave negative lens L12. The third c lens group G3c includes a biconvex positive lens L13, and a cemented lens including two lenses, a biconvex positive lens L14 and a biconcave negative lens L15.

  The optical filter FL is disposed between the third lens group G3 and the image plane I.

  FIG. 31 is a lens configuration diagram of the imaging optical system according to Example 6 of the present invention. In order from the object side to the image side, the lens unit includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a negative refractive power.

  The first lens group G1 includes a first-a lens group G1a having a positive refractive power and a first-b lens group G1b having a positive refractive power. The first-a lens group G1a includes a biconvex positive lens L1, a biconvex positive lens L2, and a biconcave negative lens L3. The first-b lens group G1b includes a cemented lens including two lenses, a negative meniscus lens L4 having a convex surface facing the object side and a positive meniscus lens L5 having a convex surface facing the object side.

  The second lens group G2 includes a cemented lens including two lenses, a biconvex positive lens L6 and a biconcave negative lens L7. The second lens group G2 is arranged on the image plane side along the optical axis. Focusing from an infinite object to a close object is performed.

  The aperture stop S is disposed between the second lens group G2 and the third lens group G3.

  The third lens group G3 is composed of three groups: a 3a lens group G3a having a positive refractive power, a 3b lens group G3b having a negative refractive power, and a third c lens group G3c having a positive refractive power. The third-b lens group G3b is moved in a direction substantially perpendicular to the optical axis to displace the imaging position of the captured image.

  The third-a lens group G3a includes a cemented lens including two lenses, a biconvex positive lens L8 and a negative meniscus lens L9 having a convex surface facing the image side. The third lens group G3b includes a cemented lens including two lenses, a biconvex positive lens L10 and a biconcave negative lens L11, and a biconcave negative lens L12. The 3c lens group G3c includes a biconvex positive lens L13 and a cemented lens including two lenses, a biconvex positive lens L14 and a biconcave negative lens L15.

  The optical filter FL is disposed between the third lens group G3 and the image plane I.

  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.

  BF represents back focus.

  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] indicates a value such as a focal length when the shooting distance is INF. Further, in Numerical Example 1, it is 3500 mm, in Numerical Example 2, it is 4500 mm, in Numerical Example 3, it is 6000 mm, in Numerical Example 4, it is 6000 mm, and in Numerical Example 5, it is 3500 mm. In Numerical Example 6, values such as a focal length at 3500 mm are shown.

  [Variable interval data] indicates values of the variable surface interval and BF (back focus) when the shooting distance is INF. Further, in Numerical Example 1, it is 3500 mm, in Numerical Example 2, it is 4500 mm, in Numerical Example 3, it is 6000 mm, in Numerical Example 4, it is 6000 mm, and in Numerical Example 5, it is 3500 mm. In Numerical Example 6, the values of the variable surface interval and BF (back focus) at 3500 mm are shown.

  [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
Object ∞ (d0)
1 279.6739 14.9867 1.43700 95.10
2 -293.8016 36.9998
3 -198.9937 3.0000 1.80611 40.73
4 -898.9366 2.0010
5 202.4142 14.7159 1.43700 95.10
6 -393.7116 100.6465
7 100.5861 2.3000 1.72916 54.67
8 52.3940 12.6635 1.59282 68.62
9 346.3033 (d9)
10 1315.7550 3.2032 1.84666 23.78
11 -225.0287 1.6000 1.77250 49.62
12 120.9056 (d12)
13 (Aperture) ∞ 8.2693
14 370.3463 4.7840 1.65844 50.85
15 -58.4896 1.0000 1.84666 23.78
16 -139.3665 10.6788
17 83.7235 3.3809 1.75520 27.53
18 -90.9109 0.9000 1.59349 67.00
19 31.7574 4.7980
20 -70.4267 0.7000 1.72916 54.67
21 98.5304 5.5023
22 85.6968 8.0250 1.56732 42.84
23 -82.5675 0.2589
24 51.8207 6.4564 1.56732 42.84
25 -92.1162 1.0000 1.84666 23.78
26 151.0294 12.5976
27 ∞ 1.3000 1.51680 64.20
28 ∞ (BF)
Image plane ∞


[Various data]
INF 3500mm
Focal length 487.00 372.04
F number 4.11 4.11
Full angle 2ω 5.06 3.86
Statue height Y 21.63 21.63
Total lens length 404.50 404.50
Anti-vibration coefficient 2.39 2.39


[Variable interval data]
INF 3500mm
d0 ∞ 3095.4980
d9 7.5520 27.6578
d12 59.6448 39.5390
BF 75.5375 75.5375


[Lens group data]
Group Start surface Focal length
G1 1 208.44
G2 10 -185.05
G3 14 -644.77
G1a 1 322.29
G1b 7 328.91
G3a 14 216.22
G3b 17 -39.20
G3c 22 61.00

Numerical example 2
Unit: mm
[Surface data]
Surface number rd nd vd
Object ∞ (d0)
1 277.0275 21.2263 1.43700 95.10
2 -335.5898 44.0000
3 -220.3675 3.6000 1.78590 43.93
4 -1922.2641 2.0000
5 240.0018 17.7493 1.43700 95.10
6 -389.5080 126.2759
7 108.3853 3.0000 1.72916 54.67
8 56.4838 11.6548 1.59282 68.62
9 292.6583 (d9)
10 1711.0662 3.0671 1.84666 23.78
11 -247.9646 1.6800 1.77250 49.62
12 127.3415 (d12)
13 (Aperture) ∞ 23.7251
14 130.0125 5.8385 1.65844 50.85
15 -65.6132 1.0000 1.84666 23.78
16 -178.6198 7.0000
17 470.9643 2.7220 1.84666 23.78
18 -76.0164 1.0800 1.59349 67.00
19 52.7905 3.4780
20 -104.9201 0.8400 1.72916 54.67
21 66.6611 5.5364
22 82.5285 8.5170 1.54072 47.20
23 -94.8406 0.1500
24 77.2535 6.2741 1.62004 36.30
25 -79.6843 1.2000 1.84666 23.78
26 207.1350 11.0000
27 ∞ 1.3000 1.51680 64.20
28 ∞ (BF)
Image plane ∞


[Various data]
INF 4500mm
Focal length 584.99 440.96
F number 4.12 4.12
Full angle of view 2ω 4.20 3.36
Statue height Y 21.63 21.63
Total lens length 466.67 466.67
Anti-vibration coefficient 2.58 2.58


[Variable interval data]
INF 4500mm
d0 ∞ 4033.3272
d9 16.9918 39.8415
d12 46.9500 24.1003
BF 88.8163 88.8163


[Lens group data]
Group Start surface Focal length
G1 1 256.64
G2 10 -190.00
G3 14 -868.75
G1a 1 378.34
G1b 7 415.92
G3a 14 145.00
G3b 17 -41.19
G3c 22 73.12

Numerical Example 3
Unit: mm
[Surface data]
Surface number rd nd vd
Object ∞ (d0)
1 223.4199 19.6506 1.43700 95.10
2 -414.9195 58.0000
3 -213.9680 4.7988 1.78590 43.93
4 -4611.3217 2.0000
5 216.3799 15.2199 1.43700 95.10
6 -344.6887 91.0556
7 115.6324 2.3000 1.72916 54.67
8 55.2236 11.0135 1.59282 68.62
9 266.8909 (d9)
10 1809.6436 2.5639 1.84666 23.78
11 -332.2571 2.2394 1.77250 49.62
12 129.1855 (d12)
13 (Aperture) ∞ 20.8320
14 -226.5274 3.8448 1.56732 42.84
15 -50.7807 1.0000 1.83481 42.72
16 -77.2684 7.0000
17 79.8481 3.3910 1.75520 27.53
18 -112.7920 1.4396 1.59282 68.62
19 38.9858 3.6657
20 -92.5287 1.1197 1.77250 49.62
21 92.1075 5.5000
22 95.3124 3.3993 1.60342 38.01
23 -295.1898 2.0000
24 86.0725 6.1799 1.60342 38.01
25 -53.6086 1.0000 1.80809 22.76
26 24080.5737 2.0000
27 -280.5473 3.2159 1.60342 38.01
28 -65.0705 1.2000 1.80809 22.76
29 -114.1459 53.6571
30 ∞ 1.3000 1.51680 64.20
31 ∞ (BF)
Image plane ∞


[Various data]
INF 6000mm
Focal length 780.00 569.26
F number 5.75 5.75
Full angle of view 2ω 3.16 2.52
Statue height Y 21.63 21.63
Total lens length 499.50 499.50
Anti-vibration coefficient 2.75 2.75


[Variable interval data]
INF 6000mm
d0 ∞ 5500.4979
d9 29.2510 47.0277
d12 64.1270 46.3503
BF 75.5374 75.5374


[Lens group data]
Group Start surface Focal length
G1 1 266.83
G2 10 -189.40
G3 14 -435.28
G1a 1 359.30
G1b 7 583.29
G3a 14 321.33
G3b 17 -48.83
G3c 22 76.34

Numerical Example 4
Unit: mm
[Surface data]
Surface number rd nd vd
Object ∞ (d0)
1 231.3357 19.3266 1.43700 95.10
2 -408.8762 58.0000
3 -219.2671 4.7988 1.78590 43.93
4 -6353.0495 2.0000
5 211.9979 14.8561 1.43700 95.10
6 -381.2947 93.5269
7 122.1491 2.3000 1.72916 54.67
8 57.6733 10.8783 1.59282 68.62
9 294.4607 (d9)
10 670.9370 2.4069 1.84666 23.78
11 -833.8230 1.5000 1.77250 49.62
12 151.3952 (d12)
13 (Aperture) ∞ 15.1885
14 -99.6393 4.6339 1.56732 42.84
15 -41.4546 1.0000 1.83481 42.72
16 -60.7333 7.0000
17 87.3698 3.3060 1.75520 27.53
18 -108.6903 1.4396 1.59282 68.62
19 42.7542 3.3513
20 -99.0710 1.1197 1.77250 49.62
21 91.3204 5.5000
22 99.9115 3.3916 1.60342 38.01
23 -245.0297 2.0000
24 98.6661 5.6954 1.60342 38.01
25 -54.6494 1.0000 1.80809 22.76
26 -931.1708 6.4494
27 -155.8755 2.5643 1.60342 38.01
28 -68.7773 1.0000 1.80809 22.76
29 -106.7905 56.3167
30 ∞ 1.3000 1.51680 64.20
31 ∞ (BF)
Image plane ∞


[Various data]
INF 6000mm
Focal length 780.00 564.45
F number 5.76 5.76
Full angle of view 2ω 3.16 2.56
Statue height Y 21.63 21.63
Total lens length 499.50 499.50
Anti-vibration coefficient 2.75 2.75


[Variable interval data]
INF 6000mm
d0 ∞ 5500.4979
d9 22.5802 44.8880
d12 69.5342 47.2264
BF 75.5376 75.5373


[Lens group data]
Group Start surface Focal length
G1 1 273.94
G2 10 -267.55
G3 14 -269.22
G1a 1 369.78
G1b 7 596.37
G3a 14 551.33
G3b 17 -51.31
G3c 22 81.50

Numerical Example 5
Unit: mm
[Surface data]
Surface number rd nd vd
Object ∞ (d0)
1 309.9871 16.3389 1.43700 95.10
2 -275.1845 36.7800
3 -197.7700 3.0000 1.80611 40.73
4 -862.8791 2.2987
5 203.4143 14.1181 1.43700 95.10
6 -474.9011 111.0570
7 103.2130 3.0000 1.72916 54.67
8 54.3435 13.1302 1.59282 68.62
9 517.9425 (d9)
10 569.5601 3.0742 1.84666 23.78
11 -321.9291 1.2000 1.77250 49.62
12 120.2215 (d12)
13 (Aperture) ∞ 3.0038
14 -322.6058 4.2151 1.65844 50.85
15 -70.4800 1.0000 1.84666 23.78
16 -126.6655 16.7285
17 81.4011 3.6432 1.75520 27.53
18 -144.9320 0.9000 1.59349 67.00
19 36.1244 3.9522
20 -102.6136 0.7000 1.72916 54.67
21 97.4610 8.9790
22 79.3471 4.6629 1.56732 42.84
23 -125.0684 0.1608
24 67.6737 6.7189 1.56732 42.84
25 -79.8578 1.0000 1.84666 23.78
26 234.9988 11.0000
27 ∞ 1.3000 1.51680 64.20
28 ∞ (BF)
Image plane ∞


[Various data]
INF 3500mm
Focal length 487.00 368.32
F number 4.11 4.11
Full angle of view 2ω 5.06 3.98
Statue height Y 21.63 21.63
Total lens length 408.00 408.00
Anti-vibration coefficient 1.90 1.90


[Variable interval data]
INF 3500mm
d0 ∞ 3092.0000
d9 6.0005 28.2775
d12 54.0024 31.7254
BF 76.0355 76.0354


[Lens group data]
Group Start surface Focal length
G1 1 208.18
G2 10 -213.40
G3 14 -388.25
G1a 1 345.83
G1b 7 285.77
G3a 14 497.38
G3b 17 -49.43
G3c 22 74.20

Numerical Example 6
Unit: mm
[Surface data]
Surface number rd nd vd
Object ∞ (d0)
1 197.0787 14.2075 1.43700 95.10
2 -745.1275 36.8830
3 228.1856 12.5363 1.43700 95.10
4 -339.2742 3.0564
5 -320.2416 3.0000 1.77250 49.62
6 697.5694 105.5248
7 87.4526 2.3000 1.83481 42.72
8 61.1024 11.4920 1.49700 81.61
9 532.8965 (d9)
10 831.5558 3.1995 1.84666 23.78
11 -631.8486 1.2000 1.77250 49.62
12 136.6207 (d12)
13 (Aperture) ∞ 13.8885
14 207.0341 5.0539 1.65844 50.85
15 -85.8829 1.4000 1.84666 23.78
16 -184.4800 7.6965
17 138.0549 4.0734 1.75520 27.53
18 -63.7059 0.9000 1.59349 67.00
19 45.4247 3.2903
20 -100.0270 0.7000 1.72916 54.67
21 56.6828 6.0150
22 68.6013 4.4280 1.58913 61.25
23 -164.3258 4.0112
24 72.0287 6.9122 1.67270 32.17
25 -52.9933 1.0000 1.84666 23.78
26 276.6982 11.0000
27 ∞ 1.3000 1.51680 64.20
28 ∞ (BF)
Image plane ∞


[Various data]
INF 3500mm
Focal length 487.00 373.21
F number 4.12 4.12
Full angle 2ω 5.06 3.86
Statue height Y 21.63 21.63
Total lens length 410.00 410.00
Anti-vibration coefficient 2.39 2.39


[Variable interval data]
INF 3500mm
d0 ∞ 3090.0000
d9 6.0000 31.3629
d12 62.8961 37.5332
BF 76.0355 76.0355


[Lens group data]
Group Start surface Focal length
G1 1 227.02
G2 10 -221.99
G3 14 -672.70
G1a 1 374.91
G1b 7 313.37
G3a 14 180.14
G3b 17 -39.91
G3c 22 64.77

[Values for conditional expressions]
1 2 3 4 5 6
(1) f1 / f 0.428 0.439 0.342 0.351 0.427 0.466
(2) f2 / f -0.380 -0.325 -0.243 -0.343 -0.438 -0.456
(3) f3 / f -1.324 -1.485 -0.558 -0.345 -0.797 -1.381
(4) f3a / f 0.444 0.248 0.412 0.707 1.021 0.370
(5) f3b / f -0.080 -0.070 -0.063 -0.066 -0.102 -0.082
(6) f3c / f 0.125 0.125 0.098 0.104 0.152 0.133
(7) vd1ap 95.10 95.10 95.10 95.10 95.10 95.10
(8) θgF1ap-0.6483 0.0563 0.0563 0.0563 0.0563 0.0563 0.0563
+ 0.0018 × νd1ap
(9) θgF1an-0.6483 -0.0079 -0.0081 -0.0081 -0.0081 -0.0079 -0.0087
+ 0.0018 × νd1an
(10) νd1bp 68.63 68.63 68.63 68.63 68.63 81.61
(11) θgF1bp-0.6483 0.0193 0.0193 0.0193 0.0193 0.0193 0.0374
+ 0.0018 × νd1bp
(12) θgF1bn-0.6483 -0.0047 -0.0047 -0.0047 -0.0047 -0.0047 -0.0063
+ 0.0018 × νd1bn
(13) D2 / LT 0.518 0.472 0.533 0.543 0.496 0.524

G1 1st lens group G2 2nd lens group G3 3rd lens group G1a 1a lens group G1b 1b lens group G3a 3a lens group G3b 3b lens group G3c 3c lens group S Aperture stop FL Optical filter I Image surface

Claims (5)

In order from the object side to the image side, the lens unit includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a negative refractive power, and the second lens group G2. In an inner focus type imaging optical system that performs focusing by moving the lens along the optical axis,
The first lens group G1 includes a first a lens group G1a having a positive refractive power and a first b lens group G1b having a positive refractive power at the widest lens interval in the first lens group G1.
The first a lens group G1a includes at least one positive lens and at least one negative lens, and the first b lens group G1b includes one positive lens and one negative lens,
The third lens group G3 is composed of three groups in order from the object side: a third a lens group G3a having a positive refractive power, a third b lens group G3b having a negative refractive power, and a third c lens group G3c having a positive refractive power. Then, the imaging position of the photographed image is displaced by moving the third b lens group G3b in a direction substantially perpendicular to the optical axis,
An inner focus type imaging optical system satisfying the following conditional expression:
(1) 0.25 <f1 / f <0.60
(2) −0.60 <f2 / f <−0.15
(3) -2.50 <f3 / f <-0.25
(4) 0.15 <f3a / f <2.00
(5) -0.20 <f3b / f <-0.04
(6) 0.05 <f3c / f <0.25
However,
f: focal length of the entire optical system at infinity shooting f1: focal length of the first lens group G1 f2: focal length of the second lens group G2 f3: focal length of the third lens group G3 f3a: 3a lens group Focal length f3b of G3a: Focal length f3c of the third b lens group G3b: Focal length of the third c lens group G3c The imaging optical system according to claim 1, wherein the following conditional expression is satisfied.
(7) 80 <νd1ap
(8) 0.030 <θgF1ap−0.6483 + 0.0018 × νd1ap
(9) θgF1an−0.6483 + 0.0018 × νd1an <0.000
However,
νd1ap: Abbe number θgF1ap for the d-line of at least one positive lens material of the 1a lens group G1a: Portion of at least one positive lens material of the 1a lens group G1a for the g-line and F-line Dispersion ratio νd1an: Abbe number θgF1an with respect to d-line of at least one negative lens material of the 1a lens group G1a: g-line and F-line of at least one negative lens material of the 1a lens group G1a Partial dispersion ratio for The imaging optical system according to claim 1, wherein the following conditional expression is satisfied.
(10) 65 <νd1bp
(11) 0.015 <θgF1bp−0.6483 + 0.0018 × νd1bp
(12) θgF1bn−0.6483 + 0.0018 × νd1bn <0.000
However,
νd1bp: Abbe number θgF1bp of the material of the positive lens of the 1b lens group G1b with respect to the d line θgF1bp: Partial dispersion ratio of the material of the positive lens of the 1b lens group G1b with respect to the g line and F line νd1bn: 1b lens group Abbe number θgF1bn with respect to d-line of negative lens material of G1b: partial dispersion ratio of negative lens material of first-b lens group G1b with respect to g-line and F-line The second lens group is composed of a cemented lens in which one positive lens and one negative lens are cemented, and satisfies the following conditional expression. The imaging optical system described in 1.
(13) D2 / LT <0.65
However,
D2: Distance from the most object side lens surface of the second lens group to the image plane at infinity LT: Distance from the most object side lens surface of the entire optical system to the image plane at infinity   The imaging optical system according to any one of claims 2 to 4, wherein the first-a lens group G1a includes two positive lenses that satisfy the conditional expression (7) and the conditional expression (8). system.

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