JP2010002790A - Imaging lens, optical device provided therewith, and image blur correction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and high-performance imaging lens reduced in aberration fluctuation, an optical device provided therewith, and image blur correction method. <P>SOLUTION: The imaging lens includes at least a positive lens group G1; a negative lens group G2 that moves during focusing; a positive lens group G3 that moves during focusing; a negative lens group G4 that is movable so as to have a moving component substantially vertical to an optical axis; and a positive lens group G5, which are disposed in order from an object along the optical axis. The imaging lens satisfies a condition of an expression: 1.21<VR<3.0 when vibration isolation coefficient VR is defined as VR=¾(1-Bvr)×Br¾, wherein BVr is the transverse magnification of the negative lens group G4 that is movable so as to have the moving component substantially vertical to the optical axis, and Br is the transverse magnification of the whole optical system closer to the image over the negative lens group G4 that is movable so as to have the moving component substantially vertical to the optical axis. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photographing lens suitable for a digital single-lens reflex camera, a film camera, a video camera, and the like, an optical device equipped with the same, and an image blur correction method.

  Conventionally, an in-focus macro lens having an image blur correction function has been proposed (see, for example, Patent Document 1). The lens described in Patent Document 1 includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side. And a fourth lens group having a negative refractive power. The fourth lens group is composed of a negative front group and a positive rear group in order from the object side. When the optical system vibrates, the fourth lens group emits light. Image blur correction is performed by shifting in a direction substantially perpendicular to the axis.

JP 2006-106112 A

  However, the conventional lens has a relatively large entire lens system, and the lens group moved for image blur correction is also relatively large. In addition, the amount of movement for vibration isolation is large, leading to an increase in overall size. Further, higher performance has been desired for aberration correction.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a high-performance photographic lens that is small in size and has little aberration fluctuation, an optical device equipped with the photographic lens, and an image blur correction method. .

  In order to achieve such an object, the photographic lens of the present invention includes a positive lens group (in this embodiment, the positive lens group G1 or one group) arranged in order from the object side along the optical axis, and moved during focusing. Negative lens group (negative lens group G2 or 2 group in this embodiment), positive lens group (positive lens group G3 or 3 group in this embodiment) that moves during focusing, and substantially perpendicular to the optical axis. At least a negative lens group (negative lens group G4 or 4 group in this embodiment) and a positive lens group (positive lens group G5 or 5 group in this embodiment) that can move so as to have a moving component in the direction. The lateral magnification of the negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis is Bvr, and the negative lens group is movable so as to have a moving component in a direction substantially perpendicular to the optical axis. The entire optical system on the image side of the negative lens group When the lateral magnification is Br, the image stabilization coefficient is VR, and the image stabilization coefficient is defined as VR = | (1−Bvr) × Br |, the following formula 1.21 <VR <3.0 is satisfied. .

  Note that the focal length of the negative lens group that can move so as to have a moving component in a direction substantially perpendicular to the optical axis is f4, and the moving lens has a moving component in a direction substantially perpendicular to the optical axis. The most object of the negative lens group that is movable so as to have a moving component in a direction substantially perpendicular to the optical axis and the lens surface closest to the image side in the lens group located on the object side of the possible negative lens group When the air space on the optical axis at the time of focusing on infinity with the lens surface on the side is d34, it is preferable to satisfy the condition of the following expression 1.0 <(− f4) / d34 <20.0.

  The focal length of the positive lens unit located on the image side of the negative lens unit movable so as to have a moving component in a direction substantially perpendicular to the optical axis is f5, and is substantially perpendicular to the optical axis. A lens surface located closest to the image side in the lens group located on the object side of the negative lens group movable so as to have a moving component in the direction, and having a moving component in a direction substantially perpendicular to the optical axis. When the air gap on the optical axis at the time of focusing on infinity with the lens surface closest to the object in the movable negative lens group is d34, the following condition is satisfied: 1.0 <f5 / d34 <40.0 Is preferably satisfied.

  The focal length of the positive lens group that moves during focusing is f3, and the lens group located on the object side of the negative lens group that can move so as to have a moving component in a direction substantially perpendicular to the optical axis. At the infinite focus between the lens surface closest to the image side and the lens surface closest to the object in the negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis. When the air space on the optical axis is d34, it is preferable to satisfy the condition of the following expression 1.0 <f3 / d34 <18.0.

  Further, the focal length of the negative lens group that moves during focusing is set to f2, and the inside of the lens group located on the object side of the negative lens group that can move so as to have a moving component in a direction substantially perpendicular to the optical axis. At the infinite focus between the lens surface closest to the image side and the lens surface closest to the object in the negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis. It is preferable that the following formula 1.0 <(− f2) / d34 <17.0 is satisfied, where d34 is the air spacing on the optical axis.

  Further, the lens group located on the object side of the negative lens group movable so that the focal length of the positive lens group located closest to the object side is f1 and has a moving component in a direction substantially perpendicular to the optical axis. When focusing at infinity between the lens surface closest to the image side of the lens and the lens surface closest to the object in the negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis It is preferable to satisfy the condition of the following expression 1.0 <f1 / d34 <20.0, where d34 is the air spacing on the optical axis.

  In addition, it is preferable that the negative lens group that moves at the time of focusing has a negative lens and a cemented lens composed of a negative lens and a positive lens arranged in order from the object side.

  The negative lens group that moves during focusing includes a negative lens L21 and a cemented lens including a negative lens L22 and a positive lens L23 arranged in order from the object side. When the radius of curvature of the surface is ra and the radius of curvature of the image side surface of the negative lens L21 is rb, the following condition −1.0 <(rb + ra) / (rb−ra) ≦ 0 is satisfied. Is preferred.

  The positive lens group located closest to the object side includes a positive lens part group G1a and a negative lens part group G1b arranged in order from the object side, and the positive lens part group G1a and the negative lens part group. When the air space on the optical axis with G1b is Da and the focal length of the entire optical system when focusing on infinity is Fo, the following expression 0.005 <Da / Fo <0.09 is satisfied. It is preferable.

  The negative lens group that moves during focusing includes a negative lens part group G2a and a negative lens part group G2b arranged in order from the object side, and the negative lens part group G2a and the negative lens part group G2b. If the air space on the optical axis is Db and the focal length of the entire optical system when focusing on infinity is Fo, the following condition 0.02 <Db / Fo <0.08 should be satisfied. Is preferred.

  Further, the optical device of the present invention (in this embodiment, a digital single-lens reflex camera CAM) is equipped with the photographing lens.

  Further, the present invention provides a positive lens group, a negative lens group that moves when focused, a positive lens group that moves when focused, and substantially perpendicular to the optical axis, which are arranged in order from the object side along the optical axis. An image blur correction method for correcting image blur on an image plane using a photographic lens having at least a negative lens group movable so as to have a moving component in various directions, and a positive lens group, the optical axis A negative lens group movable so as to have a moving component in a direction substantially perpendicular to the horizontal axis is Bvr, and a negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis. When the lateral magnification of the entire optical system on the image side is Br, the image stabilization coefficient is VR, and the image stabilization coefficient is defined as VR = | (1−Bvr) × Br |, the following formula 1.21 <VR The condition of <3.0 is satisfied.

  According to the present invention, it is possible to provide a high-performance photographic lens having a good vibration-proof performance, a small size and a small aberration variation (particularly decentration coma aberration), an optical device including the same, and an image blur correction method. .

  Hereinafter, preferred embodiments will be described with reference to the drawings. As shown in FIG. 1, the photographing lens 1 according to this embodiment includes a positive lens group G1, a negative lens group G2 that moves in focus, and a focus lens movement that are arranged in order from the object side along the optical axis. The positive lens group G3, a negative lens group G4 movable so as to have a moving component in a direction substantially perpendicular to the optical axis, and a positive lens group G5.

  The positive lens group G1 includes a biconvex lens arranged in order from the object side, a positive meniscus lens having a convex surface facing the object side, and a cemented lens including a biconcave lens and a positive meniscus lens and having negative refractive power. The imaging distance is fixed with respect to the image plane when focusing from infinity to the closest distance.

  The negative lens group G2 includes a biconcave lens arranged in order from the object side, and a cemented lens including a biconcave lens and a positive lens having a convex surface directed toward the object side, and has a negative refractive power. When focusing on the closest distance, the lens moves from the object side to the image side.

  The positive lens group G3 includes a positive lens and a cemented lens that is composed of a negative lens and a positive lens and has a positive refractive power, which are arranged in order from the object side, and a focusing distance from infinity to the closest distance. When moving, it moves from the image side to the object side.

  The negative lens group G4 has a cemented lens including a negative lens and a positive lens and has a negative refractive power. The negative lens group G4 is caused by camera shake by moving the lens so as to have a moving component in a direction substantially perpendicular to the optical axis. This is an anti-vibration group that corrects image blur (anti-vibration). With this configuration, the negative lens group G4 can suppress changes in decentering coma, field curvature, and chromatic aberration during image stabilization. In addition, it is preferable that the cemented lens of the negative lens group G4 has a biconcave shape as a whole because changes in decentering coma and field curvature during image stabilization can be further suppressed.

  The positive lens group G5 has a negative meniscus lens with a concave surface facing the object side, arranged in order from the object side, and a biconvex lens. The focusing distance from the infinity to the closest distance is in focus with respect to the image plane. Is fixed. With this configuration, it is possible to satisfactorily correct the upper coma while keeping the spherical aberration good.

  In the present embodiment, the aperture stop S is disposed between the negative lens group G2 and the positive lens group G3, and is fixed with respect to the image plane when the shooting distance is in focus from infinity to the closest distance. Has been. With this configuration, it is possible to suppress fluctuations in field curvature during focusing and minimize aberration fluctuations during image stabilization.

  When a lens capable of short-distance shooting, such as the main photographing lens 1, is provided with an anti-vibration function, the negative lens group behind the aperture stop S (the negative lens group G4 in this embodiment) is set as the anti-vibration group. However, it is also advantageous in order to suppress fluctuations in decentering coma and field curvature during image stabilization. In addition, by providing a positive lens group (positive lens group G5 in this embodiment) behind the image stabilization group, not only can the image stabilization coefficient be set to a more optimal value, but also the decentration coma during image stabilization can be improved. It is effective and preferable.

  Here, a supplementary explanation will be given of the above-mentioned image stabilization coefficient. For image stabilization, when the image stabilization group (a lens group movable in a direction substantially perpendicular to the optical axis) is shifted (moved) in a direction perpendicular to the optical axis, the amount of image blur correction on the image plane Is obtained by the following equation.

  Image stabilization amount = Image stabilization optical system shift amount × Image stabilization coefficient

  The image stabilization coefficient is obtained when the lateral magnification of the image stabilization optical system (anti-vibration group) is Bvr and the lateral magnification of the entire optical system closer to the image side than the image stabilization optical system (image stabilization group) is Br. , Defined by the following equation (provided that Br = 1 when there is no optical element on the image plane side of the image stabilization optical system (anti-vibration group)).

  Anti-vibration coefficient = | (1-Bvr) × Br |

  Therefore, when the image stabilization coefficient is 1, the image blur correction amount is equal to the image stabilization optical system shift amount. When the image stabilization coefficient is 1 or more, a sufficient image blur correction amount for the image plane can be obtained with a small shift amount of the image stabilization group. However, if the image stabilization coefficient is too large, aberration fluctuation during image stabilization and sensitivity during assembly increase, which is not preferable. Therefore, there is practically an optimum amount. In the present embodiment, it is desirable to determine the refractive power of each lens group so that the image stabilization coefficient satisfies the range of the following conditional expression (1). If this range is satisfied, in the present embodiment, it is possible to suppress changes in decentering coma and field curvature during image stabilization without increasing the size of the optical system.

  Hereinafter, the photographing lens 1 according to the present embodiment will be described along each conditional expression.

  In the photographic lens 1, the lateral magnification of the negative lens group that can move so as to have a moving component in a direction substantially perpendicular to the optical axis based on the above configuration is Bvr, and the imaging lens 1 is substantially perpendicular to the optical axis. The lateral magnification of the entire optical system closer to the image side than the negative lens group movable so as to have a moving component in the direction is Br, the image stabilization coefficient is VR, and the image stabilization coefficient is VR = | (1−Bvr) × When defined as Br |, the condition of the following formula (1) is satisfied.

  1.21 <VR <3.0 (1)

  The conditional expression (1) is a conditional expression that optimizes the image stabilization coefficient VR. The magnitude of the anti-vibration coefficient VR is closely related to good correction of various aberrations such as decentering coma and curvature of field generated during anti-vibration, the size of the anti-vibration group, and the enlargement of the anti-vibration mechanism. For this reason, it is desirable to set the conditional expression (1) to an optimum value in order to provide a small-sized photographing lens with an anti-vibration function having good performance.

  Here, if the upper limit value of the conditional expression (1) is exceeded, an attempt to secure a predetermined image blur correction amount results in the image blur correction coefficient VR becoming too large, and the image stabilization correction optical system shift for image blur correction. The amount is very small. Therefore, the control accuracy of image stabilization becomes severe, and it is not preferable because accurate control can be performed. In addition, the anti-vibration group and other lens groups have a strong refractive power as a result, which is not preferable because fluctuations in decentering coma and curvature of field at the time of anti-vibration increase. Note that it is preferable to set the upper limit value of conditional expression (1) to 2.5 because there is a better effect of correcting decentration coma and curvature of field. Further, by setting the upper limit value of conditional expression (1) to 2.0, more preferably 1.8, the effect of the present embodiment can be exhibited to the maximum.

  On the other hand, if the lower limit value of the conditional expression (1) is not reached, the image stabilization coefficient VR becomes smaller. Therefore, if a predetermined image blur correction amount is to be ensured, the image stabilization optical system shift amount becomes extremely large. As a result, the size of the vibration-proof group becomes large, which results in an increase in the size of the vibration-proof mechanism and an increase in the size of the entire lens barrel. Further, in aberration correction, the balance of refractive power between the positive lens group and the negative lens group is lost. As a result, correction of spherical aberration deteriorates, and the difference due to the wavelength of spherical aberration tends to increase. In addition, if a predetermined image blur correction amount is to be ensured, the amount of movement during image stabilization increases, which may cause deterioration in eccentric coma and field curvature, which is not preferable. Note that it is more preferable to set the lower limit value of conditional expression (1) to 1.24, more preferably 1.27, since it is advantageous in correcting optical performance during image stabilization, particularly decentration coma. Further, by setting the lower limit value of the conditional expression (1) to 1.29, more preferably 1.31, it is possible to maximize the effects of the present embodiment.

  In the present embodiment, the focal length of the negative lens group G4 that can move so as to have a moving component in a direction substantially perpendicular to the optical axis is f4, and the moving component in a direction substantially perpendicular to the optical axis. The lens surface closest to the image side in the lens group (positive lens group G3 in the present embodiment) located immediately before the object side of the negative lens group G4 that can move so as to have a substantially perpendicular to the optical axis When the air space on the optical axis at the time of focusing on infinity with the lens surface closest to the object in the negative lens group G4 movable so as to have a moving component in the direction is d34, the following equation (2) It is preferable to satisfy the conditions.

    1.0 <(-f4) / d34 <20.0 (2)

  The conditional expression (2) is a conditional expression that optimizes the focal length f4 of the negative lens group G4 that can move so as to have a moving component in a direction substantially perpendicular to the optical axis, that is, a so-called anti-vibration group G4. The magnitude of the refractive power is indicated by the length of the focal length of the image stabilizing group G4. Further, increasing or decreasing the focal length f4 of the anti-vibration group G4 results in changing the magnification from the above-described equation of the anti-vibration coefficient VR. Therefore, the conditional expression (2) is an element for setting the image stabilization coefficient VR to an optimum value as a result.

  Conditional expression (2) is expressed by the lens surface closest to the image side in the lens group (positive lens group G3) located on the object side of the image stabilization group G4 and the lens surface closest to the object side in the image stabilization group G4. For example, when the aperture stop S is disposed closer to the object side than the image stabilization group G4, the aperture stop S and the image stabilization group G4 This is to keep the distance at an optimal value. When the distance between the aperture stop S and the vibration isolation group G4 is extremely short, the vibration isolation mechanism and the diaphragm mechanism cause mechanical interference. When the distance between the aperture stop S and the vibration isolation group G4 is significantly far away, paraxial pupil rays travel around the vibration isolation group G4. In particular, it causes fluctuations in field curvature at the time of image stabilization and an increase in decentration coma, which is not preferable in either case. Therefore, it can be seen that it is necessary to set the air gap d34 to an optimum value.

  Here, if the upper limit value of the conditional expression (2) is exceeded, focusing on the focal length f4 of the image stabilization group G4, the negative refractive power is significantly weakened, resulting in a decrease in the image stabilization coefficient VR. In order to obtain a predetermined image blur correction amount, it is necessary to increase the shift amount of the image stabilization group G4, which is not preferable because the size of the image stabilization mechanism is increased. In addition, aberration fluctuations at the time of image stabilization, particularly fluctuations in eccentric coma aberration, are not preferable. Next, when focusing at infinity between the lens surface closest to the image side in the lens group (positive lens group G3) on the object side of the image stabilization group G4 and the lens surface closest to the object side in the image stabilization group G4 Focusing on the air gap d34 on the optical axis, if it exceeds the upper limit value of the conditional expression (2), it means that the air gap d34 becomes remarkably small. Mechanical interference will occur, making the configuration difficult. Note that it is more preferable to set the upper limit value of conditional expression (2) to 17.0 because it is effective in correcting coma and reducing the size. Further, by setting the upper limit of conditional expression (2) to 15.0, more preferably 10.0, the effect of the present embodiment can be exhibited to the maximum.

  On the other hand, if the lower limit value of the conditional expression (2) is not reached, attention is first focused on the focal length f4 of the image stabilizing group G4. This is not preferable because it causes fluctuations in the surface curvature and the performance is significantly deteriorated. Next, when focusing at infinity between the lens surface closest to the image side in the lens group (positive lens group G3) on the object side of the image stabilization group G4 and the lens surface closest to the object side in the image stabilization group G4 Focusing on the air interval d34 on the optical axis, if it falls below the lower limit value of the conditional expression (2), it means that the air interval d34 becomes remarkably large. Since it passes through the periphery of G4, fluctuations in field curvature and an increase in decentering coma during vibration prevention are particularly undesirable. Note that it is more preferable to set the lower limit value of conditional expression (2) to 2.0 because it is advantageous to correct optical performance during vibration isolation, particularly coma. Further, by setting the lower limit value of the conditional expression (2) to 4.0, more preferably to 5.0, the effect of the present embodiment can be maximized.

  In the present embodiment, the positive lens group G5 located on the image side of the negative lens group G4 (anti-vibration group) movable so as to have a moving component in a direction substantially perpendicular to the optical axis (however, the negative When there are a plurality of positive lens groups on the image side from the lens group G4, the focal length of the most positive lens group on the object side is f5, and the lens can be moved so as to have a moving component in a direction substantially perpendicular to the optical axis. The lens surface located on the object side of the negative lens group G4 (positive lens group G3 in this embodiment) has a moving component in a direction substantially perpendicular to the optical axis with respect to the lens surface closest to the image side. It is preferable that the condition of the following expression (3) is satisfied, where d34 is the air spacing on the optical axis when focusing on infinity with the lens surface closest to the object in the movable negative lens group G4.

  1.0 <f5 / d34 <40.0 (3)

  The conditional expression (3) is a conditional expression in which the focal length f5 of the positive lens group G5 located on the image side from the image stabilizing group G4 is optimized. The positive lens group G5 is involved in correction of upward coma, curvature of field, and lateral chromatic aberration in terms of aberration correction, and the magnitude of the anti-vibration coefficient during anti-vibration, and hence fluctuations in eccentric coma during anti-vibration and It is involved in fluctuations in field curvature.

  If the upper limit value of the conditional expression (3) is exceeded, it means that the focal length f5 of the positive lens group G5 is increased, and the balance of the refractive power with the anti-vibration group G4 having negative refractive power is lost. As a result, upper coma and curvature of field deteriorate, which is not preferable. It is more preferable to set the upper limit value of conditional expression (3) to 35.0 because it is advantageous to correct upper coma. Further, by setting the upper limit value of conditional expression (3) to 29.0, more preferably 26.0, the effect of the present embodiment can be maximized.

  On the other hand, when the value falls below the lower limit value of the conditional expression (3), it means that the focal length f5 of the positive lens group G5 is decreased, that is, the refractive power of the positive lens group G5 is remarkably increased. In this case, the correction of the upper coma aberration and the field curvature is deteriorated, and the eccentric coma aberration and the fluctuation of the field curvature at the time of image stabilization are also deteriorated. Note that it is more preferable to set the lower limit of conditional expression (3) to 5.0, which is effective in correcting coma during image stabilization. Further, by setting the lower limit of conditional expression (3) to 7.0, more preferably 10.0, the effect of the present embodiment can be maximized.

  In this embodiment, the focal length of the positive lens group G3 that moves at the time of focusing is f3, and the negative lens group G4 that can move so as to have a moving component in a direction substantially perpendicular to the optical axis (anti-vibration group). ) On the object side of the lens group (positive lens group G3 in the present embodiment), and a negative surface that can move so as to have a moving component in a direction substantially perpendicular to the optical axis with respect to the lens surface closest to the image side. It is preferable to satisfy the condition of the following expression (4), where d34 is the air space on the optical axis when focusing on infinity with the lens surface closest to the object side in the lens group G4.

  1.0 <f3 / d34 <18.0 (4)

  The conditional expression (4) is a conditional expression that optimizes the focal length f3 of the positive lens group G3 that moves during focusing. In the case where the positive lens group G3 is an optical system having an ability to focus from an infinite distance to an equal magnification, as in the present embodiment, near-field aberration fluctuations, particularly field curvature fluctuations. It plays an effective role in suppressing fluctuations in spherical aberration, and the effect is that when the positive lens group G3 having a predetermined refractive power is focused from an infinite object point to a near object point, the object direction is increased. Achieved by moving.

  Here, when the upper limit value of the conditional expression (4) is exceeded, the focal length f3 of the positive lens group G3 is increased, the refractive power is significantly weaker than the optimum value, and the balance with the front and rear lens groups is lost. As a result, the spherical aberration is excessively corrected, and the field curvature is also deteriorated. If the upper limit value of conditional expression (4) is set to 13.7, spherical aberration correction is advantageous, which is more preferable. Further, by setting the upper limit of conditional expression (4) to 13.0, more preferably 12.0, the effect of the present embodiment can be maximized.

  On the other hand, when the value falls below the lower limit value of the conditional expression (4), the focal length f3 of the positive lens G3 becomes small, and the refractive power is significantly stronger than the optimum value. In this case, the balance between the front and rear lens groups is lost, and as a result, the spherical aberration is displaced undercorrection, and the aberration correction of the entire lens system is deteriorated. Note that it is more preferable to set the lower limit value of conditional expression (4) to 2.0 because spherical aberration correction is improved. Further, by setting the lower limit of conditional expression (4) to 4.0, more preferably 7.0, the effect of the present embodiment can be maximized.

  In this embodiment, the negative lens group G2 (anti-vibration group) is movable so as to have a moving component in a direction substantially perpendicular to the optical axis, where f2 is the focal length of the negative lens group G2 that moves during focusing. ) On the object side of the lens group (positive lens group G3 in the present embodiment), and a negative surface that can move so as to have a moving component in a direction substantially perpendicular to the optical axis with respect to the lens surface closest to the image side. It is preferable that the condition of the following expression (5) is satisfied, where d34 is the air space on the optical axis when focusing on infinity with the lens surface closest to the object side in the lens group G4.

  1.0 <(-f2) / d34 <17.0 (5)

  The conditional expression (5) is a conditional expression that optimizes the focal length f2 of the negative lens group G2 that moves during focusing. Note that the negative lens group G2, as in this embodiment, is an optical system having an ability to focus from an infinite distance to an equal magnification of the photographing magnification, as in the case of this embodiment, near-field aberration fluctuations, particularly field curvature fluctuations. It plays an effective role in suppressing fluctuations in spherical aberration, and its effect is that when the negative lens group G2 having a predetermined refractive power is focused from an infinite object point to a close object point, the image direction Achieved by moving to.

  Here, when the upper limit value of the conditional expression (5) is exceeded, the negative refractive power of the negative lens group G2 becomes weak. As a result, the spherical aberration is displaced undercorrection at a short distance, resulting in an increase in short distance fluctuation, which is not preferable. In addition, the back focus is shortened, which is not preferable. Note that it is more preferable to set the upper limit of conditional expression (5) to 16.0 because spherical aberration can be corrected satisfactorily. Further, by setting the upper limit of conditional expression 4 to 15.5, more preferably 15.0, the effect of the present embodiment can be maximized.

  On the other hand, when the lower limit value of the conditional expression (5) is not reached, the negative refractive power of the negative lens group G2 becomes strong, the spherical aberration is over-corrected at a short distance, and the field curvature also fluctuates. Short-distance fluctuations increase, which is not preferable. Further, the back focus is remarkably long, which leads to an increase in the size of the entire lens system. Note that it is more preferable to set the lower limit value of conditional expression (5) to 2.0 because it is advantageous to correct spherical aberration and field curvature. Further, by setting the lower limit of conditional expression (5) to 4.0, more preferably to 5.0, the effect of the present embodiment can be maximized.

  In this embodiment, the negative lens group G4 (vibration-proof) is movable so that the focal length of the positive lens group G1 located closest to the object side is f1, and has a moving component in a direction substantially perpendicular to the optical axis. The lens surface (the positive lens group G3 in this embodiment) located on the object side of the lens group is movable so as to have a moving component in a direction substantially perpendicular to the optical axis. It is preferable to satisfy the condition of the following expression (6), where d34 is the air spacing on the optical axis when focusing on infinity with the lens surface closest to the object in the negative lens group G4.

  1.0 <f1 / d34 <20.0 (6)

  The conditional expression (6) is a conditional expression that optimizes the focal length f1 of the positive lens group G1 closest to the object side. The positive lens group G1 is fixed at the time of focusing, and has a role of satisfactorily correcting spherical aberration and downward coma aberration over the entire area.

  Here, when the value exceeds the upper limit value of the conditional expression (6), it means that the focal length f1 of the positive lens group G1 is increased and the refractive power is weakened, which is not preferable because the spherical aberration is excessively displaced. In addition, the back focus is increased, and the outer diameter of the lens is increased in order to obtain a predetermined F number. If the upper limit value of conditional expression (6) is set to 16.5, spherical aberration can be corrected well, which is more preferable. Further, by setting the upper limit of conditional expression (6) to 16.0, more preferably 13.0, the effect of the present embodiment can be maximized.

  On the other hand, if the lower limit value of the conditional expression (6) is not reached, it means that the focal length f1 of the positive lens group G1 becomes small and the refractive power becomes remarkably strong. Furthermore, the field curvature also varies, which is not preferable. In addition, the back focus is shortened, which is not preferable. If the lower limit value of conditional expression (6) is set to 2.0, correction of spherical aberration and field curvature is advantageous and more preferable. Further, by setting the lower limit of conditional expression (6) to 4.0, more preferably 7.0, the effect of the present embodiment can be maximized.

  Further, in the present embodiment, the negative lens group G2 that moves at the time of focusing has a negative lens L21 and a cemented lens composed of a negative lens L22 and a positive lens L23 arranged in order from the object side, and the negative lens L21. When the radius of curvature of the object side surface of the lens is denoted by ra and the radius of curvature of the image side surface of the negative lens L21 is denoted by rb, it is preferable that the condition of the following expression (7) is satisfied.

  −1.0 <(rb + ra) / (rb−ra) ≦ 0 (7)

  The conditional expression (7) is a conditional expression related to the shape factor (q factor) of the negative lens L21 in the negative lens group G2 that moves during focusing. Note that the negative lens group G2 includes a negative lens L21 and a cemented lens composed of the negative lens L22 and the positive lens L23 arranged in order from the object side. This is effective for suppressing fluctuations in coma and field curvature. In addition, it is desirable that the shape of the negative lens (in this embodiment, the negative lens L21) located closest to the object in the negative lens group G2 is a shape effective for spherical aberration.

  When the upper limit value of the conditional expression (7) is exceeded, the value of the shape factor (q factor) becomes positive, and the negative lens L21 has the shape of a plano-concave lens or a meniscus concave lens displaced from the plane to the convex surface on the image side. This means that the object-side surface has a large declination with respect to the angle of view, which is not preferable because the short coma aberration and the near field fluctuation of the field curvature increase. Note that it is more preferable to set the upper limit value of conditional expression (7) to −0.05 because the lower coma can be corrected well. Further, by setting the upper limit value of conditional expression (6) to −0.1, more preferably to −0.2, the effect of the present embodiment can be maximized.

  On the other hand, when the value falls below the lower limit value of the conditional expression (7), it means that the shape becomes a meniscus shape with a convex surface facing the object side. Accordingly, since the declination with respect to the light beam that determines the F number is significantly displaced, the spherical aberration is deteriorated, which is not preferable. If the lower limit value of conditional expression (7) is set to -0.95, correction of spherical aberration is advantageous and more preferable. Further, by setting the lower limit value of conditional expression (7) to −0.9, more preferably to −0.85, the effect of the present embodiment can be maximized.

  Further, in the present embodiment, the positive lens group closest to the object side (positive lens group G1 in the present embodiment) has a positive lens part group G1a and a negative lens part group G1b arranged in order from the object side. When the air space on the optical axis between the positive lens portion group G1a and the negative lens portion group G1b is Da, and the focal length at the time of focusing on the entire optical system at infinity is Fo, the following equation (8 It is preferable to satisfy the condition of

  0.005 <Da / Fo <0.09 (8)

  The conditional expression (8) is a conditional expression for setting the air interval Da between the positive lens portion group G1a and the negative lens portion group G1b in the fixed positive lens group G1 located closest to the object side to an optimum value. is there.

  Here, when the upper limit value of the conditional expression (8) is exceeded, the air space between the positive lens portion group G1a and the negative lens portion group G1b is remarkably widened, and the dead space between the focusing group G2 is increased. , And focusing becomes difficult. As a result, the size is increased, which is not preferable. In addition, if the lens is forcibly reduced in size, it is not preferable because the other lens groups are given strong refractive power, resulting in deterioration of spherical aberration and coma. Note that it is more preferable to set the upper limit value of conditional expression (8) to 0.08, since the correction of spherical aberration becomes good. Further, by setting the upper limit value of conditional expression (8) to 0.06, more preferably 0.04, the effect of the present embodiment can be maximized.

  On the other hand, if the lower limit value of the conditional expression (8) is not reached, the air space between the positive lens portion group G1a and the negative lens portion group G1b becomes remarkably narrow, and the lens contact (the lens edges are held in contact with each other). If there is a limit to the curvature of the surface, there is a restriction on the curvature of the lens surfaces of the positive lens portion group G1a and the negative lens portion group G1b facing each other. As a result, this restriction makes it difficult to correct good spherical aberration and downward coma. In addition, it also adversely affects the correction of axial chromatic aberration, which is not preferable. If the lower limit value of conditional expression (8) is set to 0.008, correction of spherical aberration is advantageous and more preferable. Further, by setting the lower limit value of conditional expression (8) to 0.01, more preferably 0.015, the effect of the present embodiment can be maximized.

  In the present embodiment, the negative lens group (in this embodiment, the negative lens group G2) that moves at the time of focusing has a negative lens part group G2a and a negative lens part group G2b that are arranged in order from the object side. When the air space on the optical axis between the negative lens portion group G2a and the negative lens portion group G2b is Db, and the focal length at the time of infinity focusing of the entire optical system is Fo, the following equation (9) It is preferable to satisfy the following conditions.

  0.02 <Db / Fo <0.08 (9)

  The conditional expression (9) is a conditional expression for setting the air distance Db between the negative lens part group G2a and the negative lens part group G2b in the negative lens group G2 moving in focus to an optimum value.

  Here, when the upper limit value of the conditional expression (9) is exceeded, the air gap between the negative lens portion group G2a and the negative lens portion group G2b is remarkably widened, and the total length of the negative lens group G2 is remarkably increased. This is not preferable because there is no dead space for moving in focus, resulting in an increase in size. In addition, if the lens is forcibly reduced in size, the other lens groups have a strong refractive power, and as a result, spherical aberration and coma aberration are deteriorated. Note that it is more preferable to set the upper limit value of conditional expression (9) to 0.07, since the correction of spherical aberration becomes good. Further, by setting the upper limit value of conditional expression (9) to 0.06, more preferably 0.05, the effect of the present embodiment can be maximized.

  On the other hand, if the lower limit value of the conditional expression (9) is not reached, the air space between the negative lens portion group G2a and the negative lens portion group G2b becomes remarkably narrow. Therefore, there is a restriction on the curvature of the lens surface closest to the image side of the negative lens portion group G2a and the lens surface closest to the object side of the negative lens portion group G2b. As a result, this restriction makes it difficult to correct good short-range fluctuations in spherical aberration and coma. If the lower limit value of conditional expression (9) is set to 0.025, it is more preferable to correct spherical aberration. Further, by setting the lower limit value of the conditional expression (9) to 0.028, further 0.03, the effect of the present embodiment can be maximized.

  FIG. 9 is a schematic cross-sectional view of a digital single-lens reflex camera CAM (optical apparatus) provided with the photographing lens having the above-described configuration. In the digital single-lens reflex camera CAM shown in FIG. 9, light from an object (subject) (not shown) is collected by the photographing lens 1 and focused on the focusing screen 4 via the quick return mirror 3. The light imaged on the focusing screen 4 is reflected a plurality of times in the pentaprism 5 and guided to the eyepiece lens 6. Thus, the photographer can observe the object (subject) image as an erect image through the eyepiece 6.

  Further, when a release button (not shown) is pressed by the photographer, the quick return mirror 3 is retracted out of the optical path, and light of an object (subject) (not shown) condensed by the photographing lens 1 is captured on the image sensor 7. Form an image. Thereby, the light from the object (subject) is captured by the image sensor 7 and recorded as an object (subject) image in a memory (not shown). In this way, the photographer can photograph an object (subject) with the camera CAM. The camera CAM described in FIG. 9 may be one that holds the photographing lens 1 in a detachable manner or may be molded integrally with the photographing lens 1. The camera CAM may be a so-called single-lens reflex camera or a camera that does not have a quick return mirror or the like.

  Hereinafter, each embodiment will be described with reference to the drawings.

(First embodiment)
A first embodiment will be described with reference to FIGS. FIG. 1 shows the configuration of the taking lens 1 according to the first embodiment. The photographic lens 1 according to the first example moves in order from the positive lens group G1, the negative lens group G2 that moves in focus, the aperture stop S, and the aperture stop S that are arranged in order from the object side along the optical axis. It has a positive lens group G3, a negative lens group G4 that can move so as to have a moving component in a direction substantially perpendicular to the optical axis, a positive lens group G5, and an optical low-pass filter O. The image plane I is formed on the image sensor 7 in FIG. 9, and the image sensor is composed of a CCD, a CMOS, or the like. In this embodiment, the optical low-pass filter O is disposed immediately before the image plane I, but actually includes the image pickup device 7 of FIG.

  The positive lens group G1 includes a positive lens part group G1a and a negative lens part group G1b arranged in order from the object side. The positive lens portion group G1a includes a biconvex positive lens L11 arranged in order from the object side, and a positive meniscus lens L12 having a convex surface facing the object side. The negative lens portion group G1b has a cemented negative lens composed of a negative lens L13 having a biconcave shape and a positive meniscus lens L14 having a convex surface facing the object side, which are arranged in order from the object side. Such a positive lens group G1 has a positive refractive power as a whole, and is fixed with respect to the image plane I when focusing from an infinite object point to a short-distance object point (hereinafter referred to as in-focus). Is done.

  The negative lens group G2 includes a negative lens part group G2a and a negative lens part group G2b arranged in order from the object side. The negative lens portion group G2a includes biconcave lenses L21 arranged in order from the object side. The negative lens portion group G2b has a cemented negative lens composed of a negative lens L22 having a biconcave shape and a positive meniscus lens L23 having a convex surface facing the object side, which are arranged in order from the object side. Such a negative lens group G2 has a negative refractive power as a whole, and moves from the object side to the image side during focusing.

  The aperture stop S determines the F number and is fixed with respect to the image plane I at the time of focusing.

  The positive lens group G3 includes a biconvex positive lens L31 arranged in order from the object side, and a cemented positive lens including a negative meniscus lens L32 having a convex surface facing the object side and a biconvex positive lens L33. However, it has a positive refractive power as a whole, and moves from the image side to the object side during focusing.

  The negative lens group G4 has a cemented negative lens composed of a biconcave negative lens L41 arranged in order from the object side and a positive meniscus lens L42 having a convex surface directed toward the object side, and has a negative refractive power as a whole. This is a so-called anti-vibration group that performs image blur correction by moving it so as to have a moving component in a direction substantially perpendicular to the optical axis.

  The positive lens group G5 includes, in order from the object side, a negative meniscus lens L51 having a convex surface facing the image side and a biconvex positive lens L52, and has a positive refractive power as a whole. It is fixed with respect to the image plane I during focusing.

  Table 1 shows each item in the first embodiment. In Table 1, f is the focal length of the entire lens system, 2ω is the angle of view (inclusive angle), Fno is the F number, BF is the back focus, β is the shooting magnification, f1 is the focal length of the positive lens group G1, and f2 is negative. The focal length of the lens group G2, f3 is the focal length of the positive lens group G3, f4 is the focal length of the negative lens group G4, and f5 is the focal length of the positive lens group G5.

  In the table, the surface number is the order of the lens surfaces from the object side along the direction in which the light beam travels, r is the radius of curvature of each lens surface, and d is the next optical surface (or image surface) from each optical surface. Is the distance on the optical axis, νd is the Abbe number with respect to the d-line, and nd is the refractive index with respect to the d-line (wavelength 587.6 nm). In addition, the surface numbers 1-27 in Table 1 respond | correspond to the surfaces 1-27 shown in FIG. In Table 1, the axial air distance between the object plane (not shown) and the positive lens group G1 is d0, the axial air distance between the positive lens group G1 and the negative lens group G2 is d7, and the negative lens group G2 And the axial air space between the aperture stop S and the positive lens group G3 is d13, and the axial air space between the positive lens group G3 and the negative lens group G4 is d18. (The value at the time of focusing on infinity corresponds to d34 in the conditional expression (1)), the axial air space between the negative lens group G4 and the positive lens group G5 is d21, and the positive lens group G5 and the optical low-pass filter O The on-axis air interval is d25. Further, in the table, values corresponding to the conditional expressions (1) to (9) are also shown.

  In the table, “mm” is generally used as the unit of focal length f, radius of curvature r, surface interval d, and other lengths. However, since the optical system can obtain the same optical performance even when proportionally enlarged or reduced, the unit is not limited to “mm”, and other appropriate units can be used. The description about the table is the same in the other examples, and the description is omitted.

(Table 1)
[Overall specifications]
f = 85.04mm, 2ω = 19.2 °, Fno = 3.6
[Lens specifications]
Surface number r d νd nd
1 153.8926 3.5000 49.60 1.772499
2 -154.5706 0.1000
3 42.5523 3.7000 55.53 1.696797
4 1245.9823 2.4500
5 -320.8002 1.3000 29.52 1.717362
6 26.6125 4.2000 48.08 1.699998
7 212.0823 d7
8 -167.4791 1.3000 55.52 1.696800
9 28.3094 2.9500
10 -216.2226 1.2000 64.12 1.516800
11 26.8641 2.0000 23.78 1.846660
12 61.2228 d12
13 Aperture stop S d13
14 56.9717 3.0000 65.47 1.603000
15 -66.1004 0.1000
16 40.1755 1.3000 27.51 1.755199
17 21.4606 4.0000 82.56 1.497820
18 -780.3046 d18
19 -364.6586 1.3000 40.77 1.883000
20 25.5565 2.0000 23.78 1.846660
21 40.2512 d21
22 -22.6638 1.5000 38.00 1.603420
23 -31.5953 0.1000
24 115.8240 3.0000 40.77 1.883000
25 -70.6649 d25
26 0.0000 2.0000 64.12 1.516800
27 0.0000 BF
[Variable interval during focusing]
Infinity short distance
f, β 85.04034 -0.50000 -1.00000
d0 0.0000 218.1695 145.3622
d7 2.30155 11.45995 18.06206
d12 18.53991 9.38151 2.77940
d13 16.15212 9.92441 2.28287
d18 5.01212 11.23983 18.88137
d21 7.58025 7.58025 7.58025
d25 50.08457 50.08457 50.08457
BF 0.68142 0.68142 0.68142
[Photographing lens group data]
Group number Group first surface Group focal length G1 1 48.7258 (= f1)
G2 8 -29.8989 (= f2)
G3 14 36.9275 (= f3)
G4 19 -39.9953 (= f4)
G5 22 73.7000 (= f5)
[Conditional expression]
Conditional expression (1) VR = 1.353
Conditional expression (2) (-f4) /d34=7.98 (d34 = 0.01)
Conditional expression (3) f5 / d34 = 14.70
Conditional expression (4) f3 / d34 = 7.37
Conditional expression (5) (-f2) /d34=5.97
Conditional expression (6) f1 / d34 = 9.72
Conditional expression (7) (rb + ra) / (rb−ra) = − 0.7108
Conditional expression (8) Da / Fo = 0.0288
Conditional expression (9) Db / Fo = 0.0347

  From the table of specifications shown in Table 1, it can be seen that the photographing lens 1 according to the present example satisfies all the conditional expressions (1) to (9).

  FIG. 2A is a diagram showing various aberrations when focusing on infinity according to the first embodiment, and FIG. 2B is a diagram illustrating image blur correction (shift amount of the image stabilizing group G4) when focusing on infinity according to the first embodiment. = -0.376) is a lateral aberration diagram when performing. FIG. 3A is a diagram showing various aberrations when focusing at a short distance (imaging magnification: −0.5 times) in the first embodiment, and FIG. 3B is an image blur correction (when focusing at a short distance in the first embodiment). It is a lateral aberration diagram when performing the shift amount of the image stabilizing group G4 = −0.546). FIG. 4A is a diagram showing various aberrations when focusing on a short distance (capturing magnification of 1.0 times) in the first embodiment, and FIG. 4B is a diagram showing aberrations when focusing on a short distance of the first embodiment (capturing magnification of 1.0 times). ) Is a lateral aberration diagram when image blur correction (shift amount of image stabilizing group G4 = −0.689) is performed.

  In each aberration diagram, FNO is an F number, Y is an image height, d is an aberration curve of a d-line (wavelength 587.6 nm), and g is an aberration curve of a g-line (wavelength 435.6 nm). In the aberration diagrams showing astigmatism, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. The explanation of the above aberration diagrams is the same in the other examples, and the explanation is omitted.

  As is apparent from the respective aberration diagrams, it is understood that the photographic lens 1 according to the first example corrects various aberrations well and has excellent imaging performance. Further, by mounting the photographing lens 1 of the first embodiment, excellent optical performance can be ensured also in the digital single-lens reflex camera CAM (optical device, see FIG. 9).

(Second embodiment)
A second embodiment will be described with reference to FIGS. FIG. 5 shows the configuration of the taking lens 1 according to the second embodiment. The photographic lens 1 according to the second example moves in order from the positive lens group G1, the negative lens group G2 that moves when in focus, the aperture stop S, and the aperture lens S that are arranged in order from the object side along the optical axis. It has a positive lens group G3, a negative lens group G4 that can move so as to have a moving component in a direction substantially perpendicular to the optical axis, and a positive lens group G5. The image plane I is formed on the image sensor 7 in FIG. 9, and the image sensor 7 is composed of a CCD, a CMOS, or the like.

  The positive lens group G1 includes a positive lens portion group G1a and a negative lens portion group G1b arranged in order from the object side. The positive lens portion group G1a includes a biconvex positive lens L11 arranged in order from the object side, and a positive meniscus lens L12 having a convex surface facing the object side. The negative lens portion group G1b has a cemented negative lens composed of a negative lens L13 having a biconcave shape and a positive meniscus lens L14 having a convex surface facing the object side, which are arranged in order from the object side. Such a positive lens group G1 has a positive refractive power as a whole, and is fixed with respect to the image plane I at the time of focusing.

  The negative lens group G2 includes a negative lens part group G2a and a negative lens part group G2b arranged in order from the object side. The negative lens portion group G2a includes biconcave lenses L21 arranged in order from the object side. The negative lens portion group G2b has a cemented negative lens composed of a negative lens L22 having a biconcave shape and a positive meniscus lens L23 having a convex surface facing the object side, which are arranged in order from the object side. Such a negative lens group G2 has a negative refractive power as a whole, and moves from the object side to the image side during focusing.

  The aperture stop S determines the F number and is fixed with respect to the image plane I at the time of focusing.

  The positive lens group G3 includes a biconvex positive lens L31 arranged in order from the object side, and a cemented positive lens including a negative meniscus lens L32 having a convex surface facing the object side and a biconvex positive lens L33. However, it has a positive refractive power as a whole, and moves from the image side to the object side during focusing.

  The negative lens group G4 includes a cemented negative lens composed of a biconcave lens L41 and a positive meniscus lens L42 having a convex surface facing the object side, which are arranged in order from the object side, and has a negative refractive power as a whole. This is a so-called anti-vibration group that performs image blur correction by moving so as to have a moving component in a direction substantially perpendicular to the optical axis.

  The positive lens group G5 includes a negative meniscus lens L51 arranged in order from the object side and having a convex surface facing the image side, and a biconvex positive lens L52. The positive lens group G5 has a positive refractive power as a whole, and is in focus. The time is fixed relative to the image plane I.

  Table 2 shows each item in the second embodiment. Note that surface numbers 1 to 25 in Table 2 correspond to surfaces 1 to 25 shown in FIG. In Table 2, the on-axis air distance between the positive lens group G1 and the negative lens group G2 is d7, the on-axis air distance between the negative lens group G2 and the aperture stop S is d12, and the aperture stop S and the positive lens group. The axial air gap between G3 and d3 is d13, and the axial air gap between the positive lens group G3 and the negative lens group G4 is d18 (the value at the time of focusing on infinity corresponds to d34 in the conditional expression (1)). The axial air space between the lens group G4 and the positive lens group G5 is d21. Further, in the table, values corresponding to the conditional expressions (1) to (9) are also shown.

(Table 2)
[Overall specifications]
f = 85.04mm, 2ω = 19.2 °, Fno = 3.6
[Lens specifications]
Surface number r d νd nd
1 76.3604 4.5000 49.60 1.772499
2 -148.8912 0.1000
3 47.5894 3.0000 55.53 1.696797
4 156.5583 1.3000
5 -295.4947 1.3000 29.52 1.717362
6 29.2740 4.2000 48.08 1.699998
7 268.6211 d7
8 -257.6864 1.3000 64.12 1.516800
9 25.1073 3.5000
10 -81.4668 1.3000 64.12 1.516800
11 29.1916 1.8000 23.78 1.846660
12 58.9804 d12
13 Aperture stop S d13
14 48.3475 3.0000 63.38 1.618000
15 -105.1379 0.1000
16 45.0100 1.3000 27.51 1.755199
17 20.9466 4.5000 82.56 1.497820
18 -113.1907 dd18
19 -163.2115 1.3000 37.16 1.834000
20 19.3875 2.3000 23.78 1.846660
21 41.5812 d21
22 -22.7307 1.5000 58.90 1.518229
23 -30.7407 0.1000
24 117.2261 3.0000 45.30 1.795000
25 -66.5666 BF
[Variable interval during focusing]
Infinity Near distance f, β 85.04034 -0.70000 -1.00000
d0 0.0000 173.6938 144.9021
d7 2.48485 14.40920 17.88657
d12 17.79213 5.86779 2.39042
d13 15.77190 6.23243 1.44831
d18 4.95458 14.49406 19.27818
d21 7.56351 7.56351 7.56351
BF 50.60784 50.60784 50.60784
[Photographing lens group data]
Group number Group first surface Group focal length G1 1 48.7258 (= f1)
G2 8 -30.2128 (= f2)
G3 14 36.9275 (= f3)
G4 19 -39.9953 (= f4)
G5 22 73.7000 (= f5)
[Conditional expression]
Conditional expression (1) VR = 1.328
Conditional expression (2) (-f4) / d34 = 8.07 (d34 = 4.955)
Conditional expression (3) f5 / d34 = 14.87
Conditional expression (4) f3 / d34 = 7.45
Conditional expression (5) (-f2) / d34 = 6.10
Conditional expression (6) f1 / d34 = 9.83
Conditional expression (7) (rb + ra) / (rb−ra) = − 0.8224
Conditional expression (8) Da / Fo = 0.0153
Conditional expression (9) Db / Fo = 0.0412

  It can be seen from the table of specifications shown in Table 2 that the photographic lens 1 according to the present example satisfies all the conditional expressions (1) to (9).

  FIG. 6A is a diagram of various aberrations when focusing on infinity according to the second embodiment. FIG. 6B is a diagram illustrating image blur correction (shift amount of the image stabilizing group G4) when focusing on infinity according to the second embodiment. = -0.383) is a lateral aberration diagram when performing. FIG. 7A is a diagram showing various aberrations when focusing at a short distance (imaging magnification: -0.7 times) in the second embodiment, and FIG. 7B is an image blur correction (when focusing at a short distance according to the second embodiment). It is a lateral aberration diagram when performing the shift amount of the image stabilizing group G4 = −0.553). FIG. 8A is a diagram showing various aberrations when focusing at a short distance (imaging magnification: 1.0) in the second embodiment, and FIG. 8 (b) is a graph showing various aberrations when focusing at a short distance in the second embodiment (imaging magnification: 1.0). ) Is a lateral aberration diagram when image blur correction is performed (shift amount of the image stabilizing group G4 = 0.700).

  As can be seen from the respective aberration diagrams, in the taking lens 1 according to the second example, various aberrations are favorably corrected and it has excellent imaging performance. Further, by mounting the photographing lens 1 of the second embodiment, excellent optical performance can be ensured also in the digital single-lens reflex camera CAM (optical device, see FIG. 9).

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

  In each embodiment, the five-group configuration is shown, but the present invention can also be applied to other group configurations such as the sixth group and the seventh group. Specifically, a configuration in which a lens or a lens group is added closest to the object side or a configuration in which a lens or a lens group is added closest to the image side may be used. Further, a configuration in which a lens or a lens group is added between the third group (positive lens group G3) and the fourth group (negative lens group G4) may be used. In this case, d34 is set immediately before the object side of the fourth group. The distance between the lens surface closest to the image side in the arranged lens group and the lens surface closest to the object side of the fourth group is set to the smallest value. Further, a negative lens group may be added between the fourth group and the fifth group (positive lens group G5) in order to improve the image stabilization performance.

  Further, in the present embodiment, a single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to be a focusing lens group that performs focusing from an object at infinity to a near object. The focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (using an ultrasonic motor or the like).

  In the present embodiment, the negative lens group that can move so as to have a moving component in a direction substantially perpendicular to the optical axis moves in a direction perpendicular to the optical axis, and is also oblique to the optical axis. Or may be swung around a point on the optical axis.

  In the present embodiment, the lens surface may be an aspherical surface. The aspheric surface may be any one of an aspheric surface by grinding, a glass mold aspheric surface in which glass is formed into an aspheric shape, and a composite aspheric surface in which resin is formed in an aspheric shape on the surface of the glass. . The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

  In the present embodiment, the aperture stop S is fixedly disposed between the second group (negative lens group G2) and the third group (positive lens group G3) with respect to the image plane I during focusing. Although it is preferable, the role may be substituted with a lens frame without providing a member as an aperture stop.

  In this embodiment, each lens surface may be provided with an antireflection film having a high transmittance in a wide wavelength region in order to reduce flare and ghost and achieve high optical performance with high contrast.

  The photographing lens 1 of the present embodiment has a focal length in terms of 35 mm film size of about 100 to 135 mm.

  In the present embodiment, it is preferable that one group (positive lens group G1) has two positive lens components and one negative lens component. Further, in the first group, it is preferable that lens components are arranged in order of positive, positive, and negative in order from the object side with an air gap interposed therebetween. It is more preferable to use a cemented lens for the negative lens component.

  In the present embodiment, it is preferable that the third group (positive lens group G3) has two positive lens components. In the third group, it is preferable to arrange the lens components in order of positive / positive in order from the object side with an air gap interposed therebetween. It is more preferable to use a cemented lens for the second positive lens component.

  In the present embodiment, it is preferable that the fifth group (positive lens group G5) has one positive lens component and one negative lens component. In the fifth group, it is preferable that lens components are arranged in order of negative / positive in order from the object side with an air gap interposed therebetween.

  In the present embodiment, it is preferable that the fourth group (negative lens group G4) is composed of one lens component. It is more preferable to use a cemented lens as the lens component.

  In addition, in order to make this invention intelligible, although demonstrated with the component requirement of embodiment, it cannot be overemphasized that this invention is not limited to this.

It is sectional drawing which shows the structure of the imaging lens which concerns on 1st Example. (A) is an aberration diagram in the infinite focus state of the first embodiment, and (b) is a lateral aberration diagram when image blur correction is performed in the infinite focus state of the first embodiment. FIG. 6A is a diagram illustrating various aberrations when focusing on a short distance in the first embodiment (imaging magnification: −0.5 times), and FIG. 5B is a diagram when image blur correction is performed when focusing on a short distance according to the first embodiment. It is a lateral aberration diagram. FIG. 5A is a diagram illustrating various aberrations when focusing on a short distance (imaging magnification: −1.0 times) according to the first embodiment, and FIG. 5B is a diagram when image blur correction is performed when focusing on a short distance according to the first embodiment. It is a lateral aberration diagram. It is sectional drawing which shows the structure of the photographic lens which concerns on 2nd Example. (A) is an aberration diagram in the infinite focus state of the second embodiment, and (b) is a lateral aberration diagram when image blur correction is performed in the infinite focus state of the second embodiment. FIG. 6A is a diagram illustrating various aberrations when focusing on a short distance in the second embodiment (shooting magnification: −0.7 times), and FIG. 5B is a diagram when image blur correction is performed when focusing on a short distance according to the second embodiment. It is a lateral aberration diagram. FIG. 6A is a diagram illustrating various aberrations when focusing on a short distance in the second embodiment (imaging magnification: −1.0 times), and FIG. 5B is a diagram when image blur correction is performed when focusing on a short distance according to the second embodiment. It is a lateral aberration diagram. FIG. 2 is a schematic cross-sectional view of a digital single-lens reflex camera equipped with the photographing lens of the present embodiment.

Explanation of symbols

1 Shooting lens G1 1 group (positive lens group)
G2 2 group (negative lens group that moves when focused)
G3 Group 3 (positive lens group that moves when focused)
G4 4 group (negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis (anti-vibration group))
G5 Group 5 (positive lens group)
S aperture stop I image plane CAM digital single lens reflex camera (optical device)

Claims (12)

A positive lens group, a negative lens group that moves when focused, a positive lens group that moves when focused, and a moving component in a direction substantially perpendicular to the optical axis, arranged in order from the object side along the optical axis. Having at least a negative lens group movable so as to have a positive lens group,
The lateral magnification of the negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis is Bvr, and the movable lens can move so as to have a moving component in a direction substantially perpendicular to the optical axis. When the lateral magnification of the entire optical system closer to the image side than the negative lens group is Br, the image stabilization coefficient is VR, and the image stabilization coefficient is defined as VR = | (1-Bvr) × Br | 21 <VR <3.0
A photographic lens characterized by satisfying the above conditions. The focal length of the negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis is f4,
The lens surface closest to the image side in the lens group located on the object side of the negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis, and substantially perpendicular to the optical axis When the air gap on the optical axis at the time of focusing at infinity with the lens surface closest to the object side of the negative lens group that can move so as to have a moving component in any direction is d34, the following expression 1.0 <( -F4) / d34 <20.0
The photographic lens according to claim 1, wherein the following condition is satisfied. The focal length of the positive lens group located on the image side from the negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis is f5,
The lens surface closest to the image side in the lens group located on the object side of the negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis, and substantially perpendicular to the optical axis When the air gap on the optical axis at the time of focusing at infinity with the lens surface closest to the object in the negative lens group movable so as to have a moving component in a specific direction is d34, the following expression 1.0 < f5 / d34 <40.0
The photographic lens according to claim 1, wherein the following condition is satisfied. The focal length of the positive lens group that moves during focusing is f3,
The lens surface closest to the image side in the lens group located on the object side of the negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis, and substantially perpendicular to the optical axis When the air gap on the optical axis at the time of focusing at infinity with the lens surface closest to the object in the negative lens group movable so as to have a moving component in a specific direction is d34, the following expression 1.0 < f3 / d34 <18.0
The photographic lens according to claim 1, wherein the following condition is satisfied. The focal length of the negative lens group that moves at the time of focusing is f2,
The lens surface closest to the image side in the lens group located on the object side of the negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis, and substantially perpendicular to the optical axis When the air gap on the optical axis at the time of focusing at infinity with the lens surface closest to the object in the negative lens group movable so as to have a moving component in a specific direction is d34, the following expression 1.0 < (-F2) / d34 <17.0
The photographic lens according to claim 1, wherein the following condition is satisfied. The focal length of the positive lens group located closest to the object side is f1,
The lens surface closest to the image side in the lens group located on the object side of the negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis, and substantially perpendicular to the optical axis When the air gap on the optical axis at the time of focusing at infinity with the lens surface closest to the object in the negative lens group movable so as to have a moving component in a specific direction is d34, the following expression 1.0 < f1 / d34 <20.0
The photographic lens according to claim 1, wherein the following condition is satisfied.   The negative lens group that moves at the time of focusing includes a negative lens and a cemented lens including a negative lens and a positive lens, which are arranged in order from the object side. The taking lens described in 1. The negative lens group that moves at the time of focusing has a negative lens L21, and a cemented lens composed of a negative lens L22 and a positive lens L23 arranged in order from the object side.
When the radius of curvature of the object side surface of the negative lens L21 is ra and the radius of curvature of the image side surface of the negative lens L21 is rb, the following equation −1.0 <(rb + ra) / (rb−ra) ≦ 0
The photographic lens according to claim 1, wherein the following condition is satisfied. The positive lens group located closest to the object side includes a positive lens part group G1a and a negative lens part group G1b arranged in order from the object side,
When the air distance on the optical axis between the positive lens portion group G1a and the negative lens portion group G1b is Da, and the focal length at the time of focusing on the infinity of the entire optical system is Fo, the following expression 0.005 < Da / Fo <0.09
The photographic lens according to claim 1, wherein the following condition is satisfied. The negative lens group that moves at the time of focusing has a negative lens part group G2a and a negative lens part group G2b arranged in order from the object side,
When the air space on the optical axis between the negative lens portion group G2a and the negative lens portion group G2b is Db, and the focal length at the time of focusing on infinity of the entire optical system is Fo, the following expression 0.02 < Db / Fo <0.08
The imaging lens according to claim 1, wherein the following condition is satisfied.   An optical apparatus comprising the photographing lens according to any one of claims 1 to 10. A positive lens group, a negative lens group that moves when focused, a positive lens group that moves when focused, and a moving component in a direction substantially perpendicular to the optical axis, arranged in order from the object side along the optical axis. An image blur correction method for correcting image blur on an image plane by using a photographing lens having at least a negative lens group movable so as to have a positive lens group,
The lateral magnification of the negative lens group movable so as to have a moving component in a direction substantially perpendicular to the optical axis is Bvr, and the movable lens can move so as to have a moving component in a direction substantially perpendicular to the optical axis. When the lateral magnification of the entire optical system closer to the image side than the negative lens group is Br, the image stabilization coefficient is VR, and the image stabilization coefficient is defined as VR = | (1-Bvr) × Br | 21 <VR <3.0
An image blur correction method characterized by satisfying the following condition.

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