JP7372770B2 - Photographic lens and imaging device - Google Patents

Description

The present invention relates to a photographic lens and an imaging device. In particular, the present invention relates to a photographic lens suitable for an imaging device using a solid-state imaging device (CCD, CMOS, etc.), such as a digital still camera or a digital video camera.

In recent years, photographing devices using solid-state image sensors, such as digital still cameras, have been widely used. Along with this, the demand for compact imaging device systems has become remarkable, and there is a rapid demand for higher performance and smaller size of the optical systems to be installed. Among the photographic lenses used in such applications, those that require a short overall length and a compact optical system are surveillance lenses, video camera lenses, digital still camera lenses, and single-lens reflex camera lenses. , lenses for mirrorless single-lens cameras, etc.

It is difficult to create a compact optical system while maintaining such high optical performance, and the following methods have been considered. For example, Patent Document 1 describes a lens arrangement that includes, in order from the object side, a positive first lens group, a negative second lens group, an aperture stop, a positive third lens group, and a positive fourth lens group. Disclosed. Focusing in this optical system is achieved by moving the negative second lens group and the positive third lens group to change their mutual distance.

Patent Document 2 describes that, in order from the object side, the camera is composed of a positive first lens group, an aperture stop, a negative second lens group, a positive third lens group, a negative fourth lens group, and a positive fifth lens group. A lens arrangement is disclosed. Focusing in this optical system is achieved by moving the negative second lens group and the negative fourth lens group to change their mutual distance.

Japanese Patent Application Publication No. 2018-97101 JP 2017-102354 Publication

However, in the case of the optical system disclosed in Patent Document 1, since the aperture stop is arranged apart from the first lens group, it is difficult to reduce the diameter of the front lens, making it difficult to reduce the size and weight of the optical system. Furthermore, in the case of the optical system disclosed in Patent Document 2, the composite focal length of the second lens group and subsequent lenses is positive, making it difficult to shorten the total optical length. As can be understood from the above, the present application aims to provide a photographic lens and an imaging device that have a short overall length and are compact.

Therefore, as a result of intensive research, we came up with the following photographic lens and imaging device in order to solve the above-mentioned problems.

A. Photographic lens according to the present application The photographic lens according to the present application is described below.

The taking lens according to the present application has a fixed lens group closest to the object side, and includes at least a first focus lens group and a second focus lens group on the image side of the fixed lens group, wherein the fixed lens The group is a lens group whose position in the optical axis direction does not change during focusing, and the position relative to the image plane is within the fixed lens group or between the fixed lens group and the adjacent lens group on the image side. The lens is provided with an aperture diaphragm having a fixed aperture, and at least the first focus lens group and the second focus lens group are moved by different amounts of movement along the optical axis to achieve focusing in a range from infinity to close range. , and is characterized by satisfying either conditional expression (1) or conditional expression (2) below.

-0.90 ≦ fr/f ≦ -0.05 (1)
however,
fr: Composite focal length of lens groups excluding fixed lens groups
f: Focal length at infinity focus

0.05 ≦ f1/f ≦0.70 (2)
however,
f1: Focal length of fixed lens group
f: Focal length at infinity focus

B. Imaging device according to the present application The imaging device according to the present application includes the above-described photographic lens and an image sensor that converts an optical image formed by the photographic lens into an electrical signal on the image plane side of the photographic lens. It is characterized by being equipped.

The photographic lens according to the present application can satisfactorily correct various aberrations from infinity to close range by optimizing the lens arrangement and refractive power arrangement of the optical system. Moreover, it becomes possible to shorten the overall optical length of the photographic lens and to make it compact. Therefore, it becomes easy to reduce the size and weight of an imaging device using this photographic lens.

FIG. 2 is a cross-sectional view of the lens configuration of the photographing lens of Example 1 when focusing at infinity. FIG. 3 is a longitudinal aberration diagram of the photographing lens of Example 1 when focusing at infinity. FIG. 3 is a longitudinal aberration diagram of the photographing lens of Example 1 during close-range focusing. 7 is a lens cross-sectional view showing the lens configuration of the photographing lens of Example 2 when focusing at infinity. FIG. FIG. 7 is a longitudinal aberration diagram of the photographing lens of Example 2 when focusing at infinity. FIG. 7 is a longitudinal aberration diagram of the photographing lens of Example 2 during close-range focusing. FIG. 7 is a lens cross-sectional view showing the lens configuration of the photographing lens of Example 3 when focusing at infinity. FIG. 7 is a longitudinal aberration diagram of the photographing lens of Example 3 when focusing at infinity. FIG. 7 is a longitudinal aberration diagram of the photographing lens of Example 3 during close-range focusing. FIG. 7 is a lens cross-sectional view showing the lens configuration of the photographing lens of Example 4 when focusing at infinity. FIG. 7 is a longitudinal aberration diagram of the photographing lens of Example 4 when focusing at infinity. FIG. 7 is a longitudinal aberration diagram of the photographing lens of Example 4 when focusing at close range. FIG. 7 is a lens cross-sectional view showing the lens configuration of the photographing lens of Example 5 when focusing at infinity. FIG. 7 is a longitudinal aberration diagram of the photographing lens of Example 5 when focusing at infinity. FIG. 12 is a longitudinal aberration diagram of the photographing lens of Example 5 when focusing at close range. FIG. 7 is a lens cross-sectional view showing the lens configuration of the photographing lens of Example 6 when focusing at infinity. FIG. 7 is a longitudinal aberration diagram of the photographing lens of Example 6 when focusing at infinity. FIG. 7 is a longitudinal aberration diagram of the photographing lens of Example 6 when focusing at close range. FIG. 7 is a lens cross-sectional view showing the lens configuration of the photographing lens of Example 7 when focusing at infinity. FIG. 7 is a longitudinal aberration diagram of the photographing lens of Example 7 when focusing at infinity. FIG. 12 is a longitudinal aberration diagram of the photographing lens of Example 7 when focusing at close range.

Embodiments of the photographic lens and the imaging device according to the present application will be described below. Note that the aspects of the photographic lens and the aspect of the imaging device according to the present application described below are one aspect of the invention according to the present application, and should not be construed as being limited to the contents described below.

A. Photography lens 1. Optical configuration of the photographic lens The photographic lens according to this application can sufficiently correct various aberrations from infinity to close range, and has the optical configuration described below in order to shorten the total optical length and make it compact. This is a characteristic.

The basic optical configuration of the photographic lens according to the present application is that there is a fixed lens group closest to the object side, and at least a first focus lens group and a second focus lens group are provided on the image side of the fixed lens group. This "fixed lens group" is a lens group whose position in the optical axis direction does not change during focusing. In the case of the photographic lens according to the present application, at least the first focus lens group and the second focus lens group are moved by different amounts of movement along the optical axis to achieve focusing in a range from infinity to close range. It is. Furthermore, in the case of the photographic lens according to the present application, an aperture diaphragm whose position is fixed with respect to the image plane is provided "within the fixed lens group" or "between the fixed lens group and the lens group adjacent to the image side." ing. In addition to these optical configurations, it is desired that a predetermined conditional expression described later be satisfied.

In the photographic lens according to the present application, the interval between each lens group changes when focusing from infinity to close range. One or more lenses are arranged in one lens group, and the air interval included in one lens group does not change when focusing from infinity to close range.

This photographic lens has a negative lens group (lens groups other than the fixed lens group, hereinafter simply referred to as "subsequent lens group") arranged closer to the image side than the fixed lens group arranged closest to the object side. Preferably, it has refractive power. This is because, in order to shorten the total optical length and at the same time facilitate telephotography, it is preferable that the front group (fixed lens group) have positive refractive power and the subsequent lens group have negative refractive power. That is, by designing the refractive power arrangement of each lens group so that the composite focal length of the subsequent lens group disposed closer to the image side than the fixed lens group is negative, the total optical length is shortened.

Furthermore, when performing focusing behavior from an object distance of infinity to a close distance, it is preferable to use a plurality of lens groups as a focus lens group and to move each lens group independently. In the case of the photographing lens according to the present application, at least a first focus lens group and a second focus lens group are provided as a fixed lens group and a subsequent lens group, and focusing behavior is performed by these focus lens groups. Necessary explanation will be given below regarding each lens group.

(1) Fixed lens group In other words, the photographic lens according to the present application consists of N lens groups (in the case of the present application, N≧3, an integer) (first lens group to Nth lens group). This fixed lens group is the first lens group. That is, this fixed lens group is a lens group having positive refractive power that is disposed closest to the object side. In this fixed lens group, if the diameter (effective diameter) of the parallel light beam passing through the lens is increased in consideration of telephotography, the lens weight becomes heavy, which is not preferable for movable as a focus lens group. Therefore, by making the lens group corresponding to this first lens group a fixed lens group that does not move in the optical axis direction, a holding mechanism for housing the lens group in the lens barrel and a drive for moving the lens group can be used. The mechanism has been made smaller, making it possible to make the entire photographic lens lighter and smaller.

There is no particular limitation on the specific lens configuration of this fixed lens group, as long as it has positive refractive power as a whole. However, since this fixed lens group has positive refractive power, it is necessary to include at least one lens having positive refractive power. If this fixed lens group is configured using a plurality of lenses having positive refractive power, it becomes easy to correct chromatic aberration and spherical aberration at the telephoto end.

Further, in the fixed lens group having a positive refractive power as a whole, it is preferable to use a lens having a negative refractive power as necessary from the viewpoint of correcting chromatic aberration and image plane property. In such a case, if the fixed lens group includes a lens having negative refractive power, this lens having negative refractive power is used in combination with any one of the lenses having positive refractive power constituting the fixed lens group. It is preferable. By cementing a lens with negative refractive power and a lens with positive refractive power in this way, compared to a configuration in which they are arranged with an air gap, eccentric errors and air gaps between single lenses can be reduced. It is possible to reduce various manufacturing errors, such as the error in . Therefore, deterioration in optical performance due to manufacturing errors can be efficiently suppressed, and variations in performance as a photographic lens can be reduced.

In the fixed lens group described above, when lenses with positive and negative refractive powers are used together, assuming that a plurality of lenses with positive refractive power are used, at least one of the positive lenses has an Abbecave value at the d-line. (hereinafter simply referred to as "Abbe's number") is preferably larger than 50, and the Abbe's number of the negative lens is preferably smaller than 50 from the viewpoint of chromatic aberration correction.

Furthermore, among the plurality of lenses having positive refractive power included in the fixed lens group, the Abbe number of at least one lens is greater than 60, so that the positive refractive power necessary for the fixed lens group as a whole is stable. Therefore, it is more preferable. As long as at least one lens satisfies this condition, there is no particular limitation on the Abbe numbers of the other lenses having positive refractive power. However, it is preferable if all the Abbe numbers of the lenses having positive refractive power included in the fixed lens group are larger than 50, since chromatic aberration correction can be performed better. Further, in order to perform better chromatic aberration correction, it is preferable that the Abbe number of all lenses having positive refractive power included in the fixed lens group is larger than 60, and it is even more preferable that the Abbe number is larger than 70.

The number of lenses constituting the fixed lens group (=first lens group) described above is not particularly limited. However, in order to achieve high optical performance while reducing the size, weight, and cost of photographic lenses, a lens with two to three positive refractive power and one to two negative refractive power lenses has been developed. It is preferable to adopt a lens configuration with a total of three to five lenses having high power.

(2) Lens group placed closer to the image side than the fixed lens group (following lens group)
The "subsequent lens group" referred to in this application is located on the image side of the fixed lens group on the object side and is composed of a plurality of lens groups, and this subsequent lens group includes a first focus lens group and a second focus lens group. A focus lens group (hereinafter, when both focus lens groups are targeted, it is simply referred to as a "focus lens group"), and an additional lens group to be described later may be provided.

Focus lens group: In the case of the photographic lens according to the present application, at least the first focus lens group and the second focus lens group are moved by different amounts of movement along the optical axis to achieve focusing in a range from infinity to close distance. Is going. The focusing behavior of the first focus lens group and the second focus lens group at this time is particularly important regarding the direction of movement, amount of movement, etc. along the optical axis, as long as focusing is possible in the range from infinity to close range. There are no limitations. By moving each focus lens group by a different amount of movement, it becomes possible to satisfactorily correct aberrations that occur depending on the shooting distance, and it is possible to maintain high optical performance from infinity to close range.

In the photographic lens related to this application, among the lens groups that move in the optical axis direction during focusing, the lens group with the smallest absolute value of focal length is defined as the first focus lens group, and the lens group with the second smallest absolute value of focal length is defined as the first focus lens group. The lens group is referred to as a second focus lens group. In addition to the first focus lens group and the second focus lens group, the camera may include a lens group that moves in the optical axis direction during focusing.

In the photographic lens related to this application, there are two or more lens groups that move in the optical axis direction when focusing, and the absolute value of the focal length is the same, and the absolute value of the focal length moves in the optical axis direction when focusing. In the case of the smallest lens group among the lens groups, one of the lens groups having the same absolute value of focal length is set as the first focus lens group and the second focus lens group.

There is no particular limitation on the number of lenses constituting the focus lens group. The number of lenses constituting the focus lens group may be one or more. However, when considering focusing on a close object at a close distance, it is preferable that the focus lens group is composed of a plurality of lenses in order to suppress fluctuations in aberrations. In such a case, it is preferable that one of them has positive refractive power and the other has negative refractive power. For example, field curvature and distortion that occur in one focus lens group with negative refractive power can be offset by the other focus lens group with positive refractive power, making it possible to obtain a photographic lens with higher optical performance. can.

Further, from the viewpoint of reducing the size and weight of the focus lens group, it is also possible to configure the focus lens group with a single lens unit. This single lens unit refers to "one lens", "a cemented lens in which a plurality of lenses are integrated without any air gap", etc. In other words, even if a single lens unit has multiple optical surfaces, only the lens surface closest to the object side and the lens surface closest to the image side are in contact with the atmosphere inside the lens barrel, and the other surfaces are The atmosphere within the lens barrel refers to the atmosphere that is not in contact with it. The lens used in the configuration of the single lens unit described above may be either a spherical lens or an aspherical lens. In this case, the aspherical lens includes a so-called compound aspherical lens having an aspherical film pasted on its surface. In particular, from the perspective of reducing the size and weight of the focus lens group while suppressing aberration fluctuations that occur when focusing on the close-up subject, the focus lens group should consist of multiple single lenses separated by air. It is preferable to use an integrated cemented lens.

When the focus lens group is composed of the above-mentioned single lens unit, the focus lens group does not include an air gap. This is because the focus lens group can be made smaller and lighter when compared to a structure in which a plurality of single lenses are arranged with an air gap in between. As a result, it is possible to reduce the size and weight of the focus drive mechanism for moving the focus lens group in the optical axis direction during focusing, and it is possible to reduce the size and weight of the entire photographic lens. Note that the concept of a photographic lens includes, in addition to various lenses, a drive mechanism for relatively moving each focus lens group, an anti-vibration mechanism to be described later, a lens barrel, and the like.

Assuming that each focus lens group is configured by arranging multiple single lenses with an air gap between them, by configuring the focus lens group with the single lens units described above, eccentric errors and Manufacturing errors such as air spacing errors can be reduced. Therefore, it is possible to design a device that suppresses deterioration in optical performance due to manufacturing errors, and it is possible to reduce variations in performance among products. Therefore, photographic lenses with high optical performance can be manufactured with high yield.

The lens surfaces included in the focus lens group described above may be only spherical surfaces, or may include aspheric surfaces.

Note that a "floating focus mechanism" is adopted as the focus drive mechanism for focusing the focus lens group in this application. This is because it is possible to efficiently improve the spherical aberration and image surface properties during focusing in a range from infinity to close distance, so it is preferable to realize a photographing lens with higher optical performance.

Additional lens group: The subsequent lens group in the present application is a general term for lens groups arranged closer to the image side than the fixed lens group. Therefore, this subsequent lens group includes the above-mentioned focus lens group. Since this focus lens group has already been described, it will be excluded from the subject of explanation here. Therefore, the following lens group described here refers to "a lens group disposed between the first focus lens group and the second focus lens group" and "a lens group disposed between the second focus lens group and the image sensor". '' and any additional lens groups. These additional lens groups are used for the purpose of correcting various aberrations, field curvature, etc. of the photographic lens as a whole. Even in this case, the entire subsequent lens group including the focus lens group needs to have negative refractive power. As described above, as long as the subsequent lens group as a whole has negative refractive power, there are no particular limitations on the specific lens configuration of this additional lens group.

In the subsequent lens group, it is preferable that the lens group disposed closest to the image side has negative refractive power. By arranging a lens group having negative refractive power closest to the image side, the telephoto ratio can be increased and the size of the photographic lens can be reduced. The lens group disposed closest to the image side may be a lens group that is fixed on the optical axis during focusing, or may be a lens group that moves on the optical axis during focusing. When the second focus lens group is disposed closest to the image side of the subsequent lens groups, the lens group disposed closest to the image side refers to the second focus lens group. Note that in order to suppress the rear lens from increasing in diameter, it is preferable that the lens group disposed closest to the image side be fixed on the optical axis during focusing.

(3) Aperture diaphragm In the case of the photographic lens according to this application, an aperture diaphragm S whose position is fixed with respect to the image plane is provided "within the fixed lens group" or "between the fixed lens group and the adjacent subsequent lens group". ing. In the lens arrangement of the photographic lens according to the present application, the relationship between the above-mentioned fixed lens group and the aperture stop S is important. That is, there is a fixed lens group disposed closest to the object side, and the aperture stop S is disposed behind it and close to the fixed lens group. By adopting such a concept, it is possible to design a lens that reduces the angle of incidence of the light beam on the image sensor while reducing the diameter of the front lens of the photographic lens. By reducing the diameter of the front element, the optical system can be made smaller and lighter. Furthermore, by reducing the angle of incidence of the light flux onto the image sensor, it is possible to suppress deterioration of captured images due to the light incident angle characteristics (CRA characteristics) of the image sensor, and it is possible to achieve higher performance of the imaging device.

In the photographic lens according to the present application, providing the aperture stop S "within the fixed lens group" refers to providing the aperture stop S at an intermediate position between the lenses when a plurality of lenses are combined to form the fixed lens group. It means. When an air gap is provided in this fixed lens group, it is preferable to provide an aperture stop S close to the lens surface on the image plane side that forms the air gap. Furthermore, in the case of the photographic lens according to the present application, it is preferable to provide an aperture stop S "between the fixed lens group and the adjacent subsequent lens group." In such a case, it is preferable to provide an aperture stop S close to the image plane side lens surface of the fixed lens group. This is because by arranging the aperture stop S at the above-mentioned position, it is possible to eliminate fluctuations in the aperture diameter due to focusing behavior that occurs during focusing, and to easily achieve a reduction in the diameter of the aperture stop.

In the case of the photographic lens according to the present application, between the "fixed lens group with positive refractive power" and the "subsequent lens group (including the focus lens group) with negative refractive power" arranged in order from the object side, It is also possible to consider this as an arrangement of an aperture stop S. Considering this, it can be said that a symmetrical refractive power arrangement is adopted with the aperture stop in between. If such a refractive power arrangement is adopted, it is possible to obtain the effect of canceling aberrations of the upper and lower rays before and after the aperture stop S. In other words, the negative distortion and positive curvature of field that occur in the fixed lens group having positive refractive power are canceled out by the negative refractive power of the subsequent lens group. Therefore, the photographing lens according to the present application in which the aperture stop S is disposed at the above-mentioned position can perform aberration correction well even with a small number of lenses, and exhibits high optical performance.

(4) Lens group structure If the lens group of the photographic lens according to the present application is expressed as consisting of N first lens group to Nth lens group, then the second lens group located on the image plane side of the fixed lens group to The first focus lens group and the second focus lens group are present in the Nth lens group. Although N at this time does not require any particular limitation, in the case of the present application, it means an integer of N≧3. That is, it means that the photographing lens in the case of N=3 is composed of only the fixed lens group, the first focus lens group, and the second focus lens group. When N≧4, it means that the fixed lens group and the subsequent lens group are composed of a first focus lens group, a second focus lens group, and at least one additional lens group.

2. Operation (1) Operation during focusing In the photographic lens according to the present application, focusing is performed using at least the first focus lens group and the second focus lens group. There are no particular limitations on the configuration, arrangement, refractive power, etc. of this focus lens group. Furthermore, when focusing on a nearby object from infinity, there are no particular limitations on the direction of movement, movement distance, etc. of these focus lens groups. Preferably, one of the first focus lens group or the second focus lens group has positive refractive power, and the other has negative refractive power. For example, it becomes possible to focus on a nearby object from infinity by moving either the first focus lens group or the second focus lens group, which has a negative refractive power, toward the image side.

The focusing behavior of the photographic lens according to the present application is performed by employing a "floating focus mechanism" that moves two focus lens groups. By adopting this floating focus mechanism, it is possible to efficiently suppress various lens aberrations that vary depending on the distance to the subject, and to bring out the high resolution performance of the lens over the entire range from infinity to close range. In particular, it is possible to improve the spherical aberration and image surface properties during close focusing at close range, and to achieve higher performance of the optical system. Furthermore, in this floating focus mechanism, it is easy to reduce the weight of each of the two focus lens groups, and it is possible to reduce the weight of the entire photographing lens. Furthermore, it is also possible to reduce the amount of movement of each focus lens group during focusing, and shorten the overall optical length.

(2) Operation during image stabilization In the photographic lens related to this application, when performing image stabilization when camera shake occurs, the image stabilization group performs image stabilization by decentering at least one lens included in the optical system. It is preferable to have. Preferably, the vibration isolation group is included in the first lens group. Furthermore, it is preferable that the biconvex lens included in the first lens group is moved in a direction perpendicular to the optical axis as the vibration-proofing group.

3. Conditional Expression The photographic lens according to the present application preferably employs the above-mentioned lens configuration and satisfies one or more of the conditional expressions described below.

3-1. Conditional expression (1)
-0.90 ≦ fr/f ≦ -0.05 (1)
however,
fr: Composite focal length of lens groups excluding fixed lens groups
f: Focal length at infinity focus

The above conditional expression (1) is for defining the combined focal length of the subsequent lens group arranged on the image side with respect to the fixed lens group. When the range of conditional expression (1) is satisfied, it becomes possible to design a photographic lens with a short overall optical length. If conditional expression (1) is less than the lower limit, the total optical length becomes long, which is not preferable because the taking lens cannot be miniaturized and the purpose of solving the problem is lost. On the other hand, if conditional expression (1) exceeds the upper limit, the negative refractive power of the subsequent lens group becomes excessive with respect to the positive refractive power of the fixed lens group, making it difficult to correct various aberrations, which is not preferable. Note that in conditional expression (1), the lower limit is −0.90, more preferably −0.80 or more, and even more preferably −0.70 or more. The upper limit is −0.05, more preferably −0.10 or less, and even more preferably −0.20 or less.

3-2. Conditional expressions (2), (2)'
0.05 ≦ f1/f ≦ 0.70 (2)
however,
f1: Focal length of fixed lens group
f: Focal length at infinity focus

This conditional expression (2) is for defining the focal length of the fixed lens group closest to the object side. When the range of conditional expression (2) is satisfied, it is possible to satisfactorily correct various aberrations from infinity to close range, and it becomes possible to shorten the overall optical length of the photographic lens and make it compact. If conditional expression (2) is less than the lower limit, the negative refractive power of the subsequent lens group becomes excessive with respect to the positive refractive power of the fixed lens group, making it difficult to correct various aberrations, which is not preferable. On the other hand, if conditional expression (2) exceeds the upper limit, the total optical length will not meet market requirements, which is undesirable. In addition, in conditional expression (2), the lower limit is 0.05, more preferably 0.10 or more, and even more preferably 0.15 or more. The upper limit is 0.70, more preferably 0.65 or less, and even more preferably 0.60 or less.

In addition, by satisfying conditional expression (1) and further satisfying conditional expression (2)' below, it becomes easier to design a photographic lens with a short overall optical length, and it becomes easier to correct various aberrations from infinity to close range. Become.

0.05 ≦ f1/f ≦ 0.95 (2)'
however,
f1: Focal length of fixed lens group
f: Focal length at infinity focus

By satisfying conditional expression (1) and satisfying conditional expression (2)', it becomes easy to effectively shorten the total optical length while exhibiting stable optical performance, and it is possible to reduce the size of the photographic lens. Preferable from this point of view. If conditional expression (2)' is less than the lower limit, it is not preferable because the effect of stabilizing the effect obtained by satisfying conditional expression (1) is not exhibited. On the other hand, if conditional expression (2)' exceeds the upper limit, the subsequent lens group for correcting various aberrations and field curvature becomes long, which is undesirable because the total optical length becomes long. In conditional expression (2)', the lower limit is 0.05, more preferably 0.10 or more, and even more preferably 0.15 or more. The upper limit is 0.95, more preferably 0.85 or less, and even more preferably 0.75 or less.

3-3. Conditional expression (3), Conditional expression (4)
In the lens group arrangement of the photographing lens related to this application, the "lens group with positive refractive power on the object side (hereinafter referred to as the "front lens group )" and "a lens group whose image side has negative refractive power (hereinafter referred to as the "rear lens group")", the following conditional expressions (3) and (4) are satisfied. By satisfying one or both of the formulas simultaneously, the total optical length can be effectively shortened, making it easy to downsize the photographic lens.

1.0 ≦ βr1 (3)
0.15 ≦ CT/f ≦ 1.00 (4)
however,
βr1: Lateral magnification of the rear lens group when focusing at infinity
CT: Distance between front lens group and rear lens group
f: Focal length at infinity focus

Conditional expression (3) defines the lateral magnification of the rear lens group. By satisfying conditional expression (3), it is possible to achieve high telephoto performance as an optical system, and at the same time, it is possible to shorten the total optical length. If conditional expression (3) is less than the lower limit, the total optical length of the photographic lens becomes long, which is not preferable. Note that conditional expression (3) is 1.0 or more, more preferably 1.1 or more, and even more preferably 1.2 or more. Although there is no particular upper limit set for conditional expression (3), as those skilled in the art will understand, it is around 10.0, and if it exceeds this, the magnification rate will be excessive and even the slightest manufacturing error will be magnified. This is not preferable because it increases the variation in product quality.

Conditional expression (4) defines the length of the interval when the point where the interval is the widest when focused at infinity is taken as the boundary. By satisfying conditional expression (4), it is possible to make the optical system highly telephoto-compatible, and at the same time, it is possible to shorten the total optical length. When conditional expression (4) is less than the lower limit, the total optical length becomes long, making it difficult to downsize the photographic lens. Further, it is not preferable because it becomes difficult to convert it into a telephoto. On the other hand, if conditional expression (4) exceeds the upper limit, the total optical length becomes long, making it difficult to downsize, which is not preferable. Note that the lower limit of conditional expression (4) is 0.15, more preferably 0.20 or more, and even more preferably 0.30 or more. The upper limit of conditional expression (4) is 1.00, more preferably 0.80 or less, and even more preferably 0.60 or less.

3-4. Conditional expression (5)
-1.00 ≦ fn/f ≦ -0.05 (5)
however,
fn: Focal length of the lens group located closest to the image side
f: Focal length at infinity focus

Conditional expression (5) is an expression for defining the focal length of the lens group disposed closest to the image side. When the range of conditional expression (5) is satisfied, the telephoto ratio of the optical system can be increased, and a photographic lens with a short optical overall length can be obtained. Further, when the aperture stop S is disposed in the fixed lens group closest to the object side, it is possible to suppress the rear lens from increasing in diameter and to downsize the optical system. If conditional expression (5) is less than the lower limit, the total optical length becomes long, which is not preferable. On the other hand, if conditional expression (5) exceeds the upper limit, the refractive power of the lens group disposed closest to the image side becomes excessively strong, making it difficult to correct field curvature, which is not preferable. Note that the lower limit of conditional expression (5) is -1.00, more preferably -0.90 or more, and even more preferably -0.80 or more. On the other hand, the upper limit of conditional expression (5) is -0.05, which is more preferably -0.10 or less, and even more preferably -0.20 or less.

3-5. Conditional expression (6)
1.2≦｜(1−βfo1 ² )×βfor ² |≦15.0 (6)
however,
βfo1: Lateral magnification of the first focus lens group when focusing on infinity βfor: Composite lateral magnification when focusing on infinity of lenses placed closer to the image side than the first focus lens group

Conditional expression (6) is the absolute value of the focus sensitivity of the first focus lens group that moves on the optical axis during focusing. That is, this is an equation for defining the amount of image plane movement when the first focus lens group moves by a unit amount. Here, the first focus lens group is a lens group that has the smallest absolute value of focal length among the lens groups that move along the optical axis when focusing from infinity to close range. When conditional expression (6) becomes less than the lower limit, the focus sensitivity of the first focus lens group decreases, the amount of movement during focusing from an object at infinity to an object at a close distance increases, and the overall optical length becomes smaller. This is difficult and undesirable. On the other hand, when conditional expression (6) exceeds the upper limit, the focus sensitivity of the first focus lens group increases, and the amount of movement of the first focus lens group to correct the shift in the focus position becomes too small. This is not preferable because it requires precision control.

As stated above, conditional expression (6) sets the focus sensitivity of the first focus lens group to an appropriate range, and allows the amount of movement during focusing from an object at infinity to an object at a close distance to be easily controlled. From the perspective of ensuring an appropriate range, if a more suitable range is defined, the lower limit of conditional expression (6) is 1.20, 1.50, 2.00, 2.50, 3.00, 3 It is preferable that the value increases stepwise to .60. Further, it is preferable that the upper limit value of conditional expression (6) becomes gradually smaller values such as 15.00, 14.00, 13.00, and 12.00.

3-6. Conditional expression (7)
0.05 ≦ | ffo1/f | ≦ 1.20 (7)
however,
ffo1: Focal length of the first focus lens group
f: Focal length at infinity focus

Conditional expression (7) is for defining the focal length of the first focus lens group. Here, the first focus lens group is a lens group that has the smallest absolute value of focal length among the lens groups that move along the optical axis when focusing from infinity to close range. When the range of conditional expression (7) is satisfied, the focus sensitivity of the first focus lens group can be set to a high and appropriate range, and the amount of movement of the first focus lens group when focusing from infinity to close range can be reduced. It becomes possible to shorten the length, and it becomes possible to obtain a photographing lens with a short optical overall length. If conditional expression (7) is less than the lower limit, the focus sensitivity of the first focus lens group becomes excessively high, which complicates the control regarding focusing behavior, which is not preferable. On the other hand, when conditional expression (7) exceeds the upper limit, the focus sensitivity of the first focus lens group becomes small, the amount of movement during focusing from an object at infinity to an object at a close distance becomes large, and the overall optical length becomes smaller. This makes it difficult and undesirable.

As stated above, if we define a more suitable range that meets the reason for defining conditional expression (7), the lower limit of conditional expression (7) is 0.05, which should be 0.10 or more. It is preferable that the value is 0.20 or more, and it is more preferable that the value is gradually increased to 0.20 or more. The upper limit of conditional expression (7) is 1.2, preferably 1.10 or less, more preferably 1.00 or less, even more preferably 0.90 or less, and 0. It is more preferable to set the value to be gradually smaller than .80.

3-7. Conditional expression (8)
0.05 ≦ | ffo2/f | ≦ 1.20 (8)
however,
ffo2: Focal length of the second focus lens group
f: Focal length at infinity focus

Conditional expression (8) defines the focal length of the second focus lens group. Here, the second focus lens group is a lens group with the smallest absolute value of focal length among the lens groups that move along the optical axis when focusing from infinity to close range, excluding the first focus lens group. . When the range of conditional expression (8) is satisfied, the focus sensitivity of the second focus lens group can be set to a high and appropriate range, and the amount of movement of the second focus lens group when focusing from infinity to close range can be reduced. It becomes possible to shorten the length, and it becomes possible to obtain a photographing lens with a short optical overall length. If conditional expression (8) is less than the lower limit, the focus sensitivity of the second focus lens group becomes excessively high, which complicates the control regarding focusing behavior, which is not preferable. On the other hand, when conditional expression (8) exceeds the upper limit, the focus sensitivity of the second focus lens group becomes small, the amount of movement during focusing from an object at infinity to an object at a close distance becomes large, and the overall optical length becomes smaller. This makes it difficult and undesirable.

As stated above, if we define a more suitable range that meets the reason for defining conditional expression (8), the lower limit of conditional expression (8) is 0.05, which is 0.10 or more. It is preferably 0.20 or more, and more preferably 0.20 or more. It is preferable to increase the value step by step. Further, the upper limit of conditional expression (7) is 1.20, which is preferably 1.10 or less, and more preferably 1.00 or less, which is a stepwise smaller value.

3-8. Conditional expression (9)
Ls/L≦0.70 (9)
however,
Ls: Distance from the lens surface closest to the object to the aperture stop
L: Distance from the lens surface closest to the object side to the lens surface closest to the image side

Conditional expression (9) is for defining the distance from the lens surface closest to the object side to the aperture stop S. When the range of conditional expression (9) is satisfied, it is possible to reduce the diameter of the front lens and at the same time, it becomes possible to reduce the angle of incidence on the image sensor. The front lens can now be made smaller in diameter, making it easier to downsize the optical system. Further, by reducing the angle of incidence on the image sensor, it is possible to suppress deterioration of captured images due to the CRA characteristics of the image sensor, and it is possible to realize higher performance of the imaging device. If the upper limit of conditional expression (9) is exceeded, the lens arrangement will be such that it is difficult to reduce the diameter of the front lens, and the diameter of the front lens cannot be reduced, which is not preferable. In order to reliably reduce the diameter of the front lens and stably reduce the angle of incidence on the image sensor, the upper limit of conditional expression (9) is preferably 0.60 or less, and 0.50 or less. More preferably, it is 0.40 or less.

3-9. Conditional expression (10)
0.10≦Lf/L≦0.80 (10)
however,
Lf: Total amount of movement of each focus lens group from infinity focusing to close focusing L: Distance from the lens surface closest to the object side to the lens surface closest to the image side

Conditional expression (10) is for defining the total amount by which each focus lens group moves during focusing from an object distance of infinity to a close distance. When the range of conditional expression (10) is satisfied, spherical aberration and image surface properties during close focusing can be improved, and the performance of the optical system can be improved. If conditional expression (10) is less than the lower limit, it is not preferable because spherical aberration and image surface properties during close focusing cannot be fully corrected. On the other hand, if conditional expression (10) exceeds the upper limit, the arrangement of lens groups other than the focus lens group will be restricted, which is not preferable.

As stated above, if we define a more suitable range that meets the reason for defining conditional expression (10), the lower limit of conditional expression (10) is 0.01, which should be 0.15 or more. It is preferably 0.20 or more, and more preferably 0.20 or more. Further, the upper limit value of conditional expression (10) is 0.80, preferably 0.75 or less, and more preferably 0.70.

3-10. Conditional expression (11)
0.5 ≦ |β| ...(11)
however,
β: Maximum imaging magnification

Conditional expression (11) is a condition determined in consideration of usability when the photographic lens according to the present application is used as a macro lens. Therefore, the reality is that there is no market demand for a photographic lens that is less than the lower limit of conditional expression (11).

B. Imaging Device The imaging device according to the present application will be explained. This imaging device is characterized by using the above-mentioned photographic lens. This imaging device includes the taking lens according to the present application, and an image sensor (image sensor) on the image plane side of the taking lens that converts an optical image formed by the taking lens into an electrical signal. .

There are no particular limitations regarding this image sensor. For example, a solid-state image sensor such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor can also be used. The imaging device in this application is suitable for imaging devices using solid-state imaging devices such as digital cameras and video cameras. Furthermore, the imaging device may be a fixed-lens imaging device in which the lens is fixed to a housing, or an interchangeable-lens imaging device such as a single-lens reflex camera or a mirrorless single-lens camera.

The imaging device includes an image processing unit that electrically processes the captured image data acquired by the image sensor to change the shape of the captured image, and image correction data used in the image processing unit to process the captured image data. It is more preferable to have an image correction data holding unit that holds an image correction program and the like. When a photographic lens is downsized, the shape of a photographed image formed on an imaging plane is likely to be distorted. At that time, the image correction data holding section holds distortion correction data for correcting the distortion of the captured image shape in advance, and the image processing section uses the distortion correction data held in the image correction data holding section. It is preferable to correct distortion in the shape of the photographed image. According to such an imaging device, it is possible to more efficiently downsize the photographing lens, and even if the entire imaging device is downsized, it is possible to obtain beautiful photographed images.

Further, the image correction data holding unit of the imaging device holds lateral chromatic aberration correction data in advance, and the image processing unit uses the lateral chromatic aberration correction data held in the image correction data holding unit to correct the lateral chromatic aberration of the photographed image. It is also preferable to perform correction. By correcting the chromatic aberration of magnification using the image processing unit, it becomes unnecessary to correct the chromatic aberration of magnification using the lens, and the number of lenses constituting the photographic lens can be reduced. Therefore, according to such an imaging device, it is possible to further downsize the photographing lens, and even if the entire imaging device is downsized, it is possible to obtain a beautiful photographed image.

Hereinafter, the photographing lens according to the present application will be specifically explained by showing examples. However, it is clearly stated that the present invention should not be interpreted as being limited to the following examples.

(1) Optical configuration of photographic lens FIG. 1 is a lens cross-sectional view showing the lens configuration of the photographic lens of Example 1 according to the present invention when focusing on infinity. Further, "IP" shown in the figure is an imaging plane, and specifically represents an imaging plane of a solid-state image sensor such as a CCD sensor or a CMOS sensor, or a film plane of a silver halide film. Further, on the object side of the image plane IP, a parallel plate (not shown) such as a cover glass having no substantial refractive power is provided. Note that since these are the same in each lens cross-sectional view shown in other examples, the explanation will be omitted below.

The photographing lens of Example 1 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a positive refractive power. It is composed of a fourth lens group G4 having a refractive power of , and a fifth lens group G5 having a negative refractive power. In this lens configuration, when focusing from an object at infinity to a nearby object, the second lens group having negative refractive power moves from the object side to the image side along the optical axis. When focusing from an object at infinity to a nearby object, the fourth lens group having positive refractive power moves from the image side to the object side along the optical axis. The aperture stop S is arranged on the image side of the first lens group G1.

In Example 1, the first lens group G1 having a positive refractive power is a fixed lens group, the second lens group G2 having a negative refractive power is a first focus lens group, and the third lens group having a positive refractive power. G3 is an additional lens group, a fourth lens group G4 having a positive refractive power is a second focus lens group, and a fifth lens group G5 having a negative refractive power is a lens group disposed closest to the image side. Here, the widest interval during infinity focusing is the air interval between the third lens group G3 and the fourth lens group G4. The configuration of each lens group will be described below.

First lens group G1: The first lens group G1, which is a fixed lens group, includes, in order from the object side, a meniscus lens L1 having a convex shape on the object side and having negative refractive power, and a biconvex lens L2 having positive refractive power. It is composed of a cemented lens that is a combination of a biconvex lens L3 having a positive refractive power and a meniscus lens L4 having a concave shape on the object side and having a negative refractive power. In order to perform image stabilization when camera shake occurs, the biconvex lens L2 included in the first lens group is used as an image stabilizing group that moves in a direction perpendicular to the optical axis to shift the image.

Second lens group G2: The second lens group G2 includes, in order from the object side, a biconcave lens L5 having a negative refractive power, a biconcave lens L6 having a positive refractive power, and a biconcave lens L7 having a negative refractive power. It consists of a cemented lens.

Third lens group G3: The third lens group G3 is a cemented lens that combines, in order from the object side, a biconvex lens L8 with positive refractive power and a meniscus lens L9 with a concave shape on the object side and negative refractive power. It consists of

Fourth lens group G4: The fourth lens group G4 is a cemented lens that combines, in order from the object side, a biconvex lens L10 having a positive refractive power and a meniscus lens L11 having a concave shape on the object side and having a negative refractive power. It consists of

Fifth lens group G5: The fifth lens group G5 includes, in order from the object side, a biconcave lens L12 having a negative refractive power and a meniscus lens L13 having a concave shape on the object side and having a negative refractive power.

(2) Numerical Examples Numerical examples to which specific numerical values of the photographic lens of Example 1 are applied will be described. Table 1 shows the surface data of the photographic lens. In Table 1, "No." is the order of the lens surface counted from the object side, "R" is the radius of curvature of the lens surface, "D" is the distance between the lens surfaces on the optical axis, and "Nd" is the d-line (wavelength "ABV" indicates the Abbe number for the d-line. "S" indicates an aperture stop. Furthermore, in the column of the distance on the optical axis of the lens surface, "D(8)", "D(13)", etc. are indicated as variable intervals where the distance on the optical axis of the lens surface changes when focusing. It means that. Note that the units of length in each table are all "mm", and all the units of angle of view are "°". Moreover, "∞" in the radius of curvature means a plane. Note that the 24th surface and the 25th surface in Table 1 are the surface data of the cover glass.

Table 2 is a specification table of the photographic lens. This specification table shows the focal length "F" of the photographing lens at each photographing distance, the F number "Fno", the half angle of view "ω", and the variable interval on the optical axis. However, Table 2 shows the respective values when focusing at infinity and when focusing at the closest distance, starting from the left side.

Table 3 shows the focal length of each lens group constituting the photographic lens.

Matters related to these tables are the same in each table shown in other examples, so the description thereof will be omitted below.

[Table 1]
No. RD Nd ABV
1 109.8306 1.0000 1.69416 31.16
2 51.0346 4.0000
3 117.6524 4.3743 1.45981 90.19
4 -86.8186 2.0000
5 43.1226 6.5155 1.73234 54.67
6 -68.8358 1.0000 2.00996 25.46
7 -492.0511 3.0000
8S ∞ D(8)
9 -132.5855 1.0000 1.87579 40.73
10 62.4141 2.7848
11 369.0285 4.4328 1.85505 23.78
12 -36.5219 1.0000 1.66152 50.85
13 68.2561 D(13)
14 92.5073 7.7105 1.62286 60.34
15 -29.4631 1.0000 1.83945 42.72
16 -45.3022 D(16)
17 59.6857 5.4776 1.66152 50.85
18 -62.6688 1.0892 1.85505 23.78
19 -279.6851 D(19)
20 -120.9857 1.0000 2.00996 25.46
21 311.4315 4.4253
22 -44.4205 1.0000 1.77621 49.62
23 -6368.6674 19.0000
24 ∞ 2.5000 1.51872 64.20
25 ∞ 1.0000

[Table 2]
Infinite β= 1.01
F 92.6989 36.6463
Fno 2.8801 5.7890
ω 12.8942 9.5622
Shooting distance ∞ 105.4453
D( 8) 3.0006 26.4018
D(13) 25.4613 2.0601
D(16) 29.2283 2.0000
D(19) 2.0000 29.2283

[Table 3]
Group Surface number Focal length
G1 1-8 56.04
G2 9-13 - 43.19
G3 14-16 56.95
G4 17-19 90.59
G5 20-23 -33.43

Further, FIGS. 2 and 3 show longitudinal aberration diagrams of the photographing lens of Example 1 when focusing on infinity and when focusing on close distance, respectively. The longitudinal aberration diagrams shown in each figure show spherical aberration (mm), astigmatism (mm), and distortion aberration (%) in order from the left side as viewed from the drawing. In the diagram showing spherical aberration, the vertical axis is the ratio to the open F value, and the horizontal axis is the defocus. The solid line is the d-line (wavelength λ = 587.6 nm), and the long dashed line is the g-line (wavelength λ = 435.8 nm). ), the short broken line indicates the spherical aberration at the C line (wavelength λ=656.3 nm). In the diagram showing astigmatism, the vertical axis shows the half angle of view, the horizontal axis shows the defocus, the solid line shows the sagittal image plane (S) for the d-line, and the dotted line shows the meridional image plane (M) for the d-line. In the diagram showing distortion aberration, the vertical axis shows half angle of view, and the horizontal axis shows %. Matters related to these longitudinal aberration diagrams are the same in the longitudinal aberration diagrams shown in other embodiments, so the description thereof will be omitted below.

(1) Optical configuration of photographic lens FIG. 4 is a lens cross-sectional view showing the lens configuration of the photographic lens of Example 2 according to the present invention when focusing on infinity. This photographic lens includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a third lens group G3 having a positive refractive power. The fourth lens group G4 has a negative refractive power, and the fifth lens group G5 has a negative refractive power. In this lens configuration, when focusing from an object at infinity to a nearby object, the second lens group having negative refractive power moves from the object side to the image side along the optical axis. When focusing from an object at infinity to a nearby object, the fourth lens group having positive refractive power moves from the image side to the object side along the optical axis. The aperture stop S is arranged on the image side of the first lens group G1.

In Example 2, the first lens group G1 having a positive refractive power is a fixed lens group, the second lens group G2 having a negative refractive power is a first focus lens group, and the third lens group having a positive refractive power. G3 is an additional lens group, a fourth lens group G4 having a positive refractive power is a second focus lens group, and a fifth lens group G5 having a negative refractive power is a lens group disposed closest to the image side. Here, the widest interval during infinity focusing is the air interval between the third lens group G3 and the fourth lens group G4. The configuration of each lens group will be described below.

First lens group G1: The first lens group G1, which is a fixed lens group, includes, in order from the object side, a biconvex lens L1 with positive refractive power, a biconvex lens L2 with positive refractive power, and a biconvex lens L2 with positive refractive power. It is composed of a cemented lens that is a combination of a biconvex lens L3 having a negative refractive power and a biconcave lens L4 having a negative refractive power. In order to perform image stabilization when camera shake occurs, the biconvex lens L2 included in the first lens group is used as an image stabilizing group that moves in a direction perpendicular to the optical axis to shift the image.

Second lens group G2: The second lens group G2 has, in order from the object side, an object-side convex meniscus lens L5 having a negative refractive power, a biconvex lens L6 having a positive refractive power, and a negative refractive power. It is composed of a cemented lens combined with a biconcave lens L7.

Third lens group G3: The third lens group G3 is a cemented lens that combines, in order from the object side, a biconvex lens L8 with positive refractive power and a meniscus lens L9 with positive refractive power and a concave shape on the object side. It consists of

Fourth lens group G4: The fourth lens group G4 is constituted by a meniscus lens L10 having positive refractive power and convex on the object side in order from the object side.

Fifth lens group G5: The fifth lens group G5 includes, in order from the object side, a biconcave lens L11 having a negative refractive power and a biconcave lens L13 having a negative refractive power.

(2) Numerical Example A numerical example to which specific numerical values of the photographic lens of Example 2 are applied will be described. Table 4 shows the surface data of the photographic lens. Table 5 shows the specifications of the photographic lens. Table 6 shows the focal length of each lens group constituting the photographic lens. Note that the 23rd surface and the 24th surface in Table 4 are the surface data of the cover glass.

Table 4 shows the surface data of the photographic lens. Table 4 shows the surface data of the photographic lens of Example 2. Table 5 shows the specifications of the photographic lens. Table 6 shows the focal length of each lens group constituting the photographic lens.

[Table 4]
No. RD Nd ABV
1 78.2621 5.6969 1.48914 70.44
2 -3523.9787 14.6583
3 95.2525 4.4532 1.49845 81.61
4 -789.3464 2.0000
5 53.2129 7.1089 1.49845 81.61
6 -141.9926 1.0000 2.00996 25.46
7 214.3517 12.4734
8S ∞ D(8)
9 342.0580 1.0000 1.96073 32.32
10 43.4974 3.2262
11 224.7823 4.1401 2.01489 19.32
12 -34.4123 1.0000 1.91048 31.31
13 64.9522 D(13)
14 412.3208 1.9948 1.93323 20.88
15 -517.5363 3.9184 1.45981 90.19
16 -46.4045 D(16)
17 36.5151 5.7421 1.43810 95.10
18 480.9011 D(18)
19 -509.1770 1.0000 1.88622 40.14
20 74.7958 9.3520
21 -83.8097 2.0000 1.96073 32.32
22 453.9922 19.0000
23 ∞ 2.5000 1.51872 64.20
24 ∞ 1.0000

[Table 5]
Infinite β= 1.01
F 194.0016 44.5337
Fno 3.9948 8.0380
ω 6.2390 4.2818
Shooting distance ∞ 207.5622
D( 8) 3.0000 26.0381
D(13) 25.1735 2.1355
D(16) 36.5620 1.9997
D(18) 2.0000 36.5620

[Table 6]
Group Surface number Focal length
G1 1-8 75.70
G2 9-13 -37.71
G3 14-16 77.06
G4 17-18 89.84
G5 19-22 -34.51

Further, FIGS. 5 and 6 show longitudinal aberration diagrams of the photographing lens of Example 2 when focusing on infinity and when focusing on close distance, respectively.

(1) Optical configuration of photographic lens FIG. 7 is a lens cross-sectional view showing the lens configuration of the photographic lens of Example 3 according to the present invention when focusing on infinity. This photographic lens includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a third lens group G3 having a positive refractive power. The fourth lens group G4 has a negative refractive power, and the fifth lens group G5 has a negative refractive power. In this lens configuration, when focusing from an object at infinity to a close object, the second lens group having negative refractive power moves from the object side to the image side along the optical axis. When focusing from an object at infinity to a nearby object, the fourth lens group with positive refractive power first moves from the image side to the object side along the optical axis, and then moves from the object side to the image side along the optical axis. Reverse direction and move. The aperture stop S is arranged on the image side of the first lens group G1.

In Example 3, the first lens group G1 having a positive refractive power is a fixed lens group, the second lens group G2 having a negative refractive power is a first focus lens group, and the third lens group having a positive refractive power. G3 is an additional lens group, a fourth lens group G4 having a positive refractive power is a second focus lens group, and a fifth lens group G5 having a negative refractive power is a lens group disposed closest to the image side. Here, the widest interval during infinity focusing is the air interval between the third lens group G3 and the fourth lens group G4. The configuration of each lens group will be described below.

First lens group G1: The first lens group G1, which is a fixed lens group, includes, in order from the object side, an object-side convex meniscus lens L1 having negative refractive power, a biconvex lens L2 having positive refractive power, It is composed of a cemented lens that is a combination of a biconvex lens L3 having a positive refractive power and a meniscus lens L4 having a concave shape on the object side and having a negative refractive power. In order to perform image stabilization when camera shake occurs, the biconvex lens L2 included in the first lens group is used as an image stabilizing group that moves in a direction perpendicular to the optical axis to shift the image.

Second lens group G2: The second lens group G2 has, in order from the object side, a biconcave lens L5 having a negative refractive power, a meniscus lens L6 having a concave shape on the object side having a positive refractive power, and a negative refractive power. It is composed of a cemented lens combined with a meniscus lens L7 having a concave shape on the object side.

Third lens group G3: The third lens group G3 is a cemented lens that combines, in order from the object side, a meniscus lens L8 having a negative refractive power and a convex shape on the object side and a biconvex lens L9 having a positive refractive power. It consists of

Fourth lens group G4: The fourth lens group G4 is composed only of a biconvex lens L10 having positive refractive power.

Fifth lens group G5: The fifth lens group G5 includes only a meniscus lens L11 having a negative refractive power and having a concave shape on the object side.

(2) Numerical Example A numerical example to which specific numerical values of the photographic lens of Example 3 are applied will be described. Table 7 shows the surface data of the photographic lens. Table 8 shows the specifications of the photographic lens. Table 9 shows the focal length of each lens group constituting the photographic lens. Note that the 21st surface and the 22nd surface in Table 7 are the surface data of the cover glass.

[Table 7]
No. RD Nd ABV
1 59.8538 1.0000 2.00912 29.13
2 35.9885 5.5230
3 95.9927 4.6325 1.49845 81.61
4 -90.4529 2.0000
5 40.0885 8.3623 1.73234 54.67
6 -45.4786 1.0000 2.01489 19.32
7 -80.2695 3.0000
8S ∞ D(8)
9 -53.2018 1.0000 2.00912 29.13
10 44.9292 4.5126
11 -104.1079 5.3627 2.01489 19.32
12 -23.2212 1.0000 1.74690 49.22
13 -728.2143 D(13)
14 1212.2195 1.0000 1.69416 31.16
15 417.0527 6.4483 1.77621 49.62
16 -39.8191 D(16)
17 99.2085 6.0063 1.49845 81.61
18 -52.4238 D(18)
19 -39.4968 1.0000 2.01489 19.32
20 -2451.5099 45.0000
21 ∞ 2.0000 1.51872 64.20
22 ∞ 1.0000

[Table 8]
Infinite β= 1.01
F 92.7000 54.1626
Fno 2.8809 5.7849
ω 12.8215 8.4882
Shooting distance ∞ 118.4442
D( 8) 3.0000 17.5485
D(13) 16.5485 2.0000
D(16) 21.5485 18.4509
D(18) 2.1768 5.2744

[Table 9]
Group Surface number Focal length
G1 1-8 38.33
G2 9-13 -27.43
G3 14-16 49.50
G4 17-18 69.73
G5 19-20 -39.56

Further, FIGS. 8 and 9 show longitudinal aberration diagrams of the photographing lens of Example 3 when focusing on infinity and when focusing on close distance, respectively.

(1) Optical configuration of photographic lens FIG. 10 is a lens cross-sectional view showing the lens configuration of the photographic lens of Example 4 according to the present invention when focusing on infinity. This photographic lens includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a negative refractive power, and a positive refractive power. The fourth lens group G4 has a positive refractive power, the fifth lens group G5 has a positive refractive power, and the sixth lens group G6 has a negative refractive power. When focusing from an object at infinity to a nearby object, the second lens group with negative refractive power and the third lens group with negative refractive power move independently from the object side to the image side along the optical axis. do. When focusing from an object at infinity to a nearby object, the fifth lens group having positive refractive power moves from the image side to the object side along the optical axis. The aperture stop S is arranged on the image side of the first lens group G1.

In Example 4, the first lens group G1 having a positive refractive power is a fixed lens group, the second lens group G2 having a negative refractive power is a first focus lens group, and the third lens group having a negative refractive power. G3 is an additional lens group, the fourth lens group G4 has a positive refractive power, the fifth lens group G5 has a positive refractive power, the second focus lens group, and the sixth lens group has a negative refractive power. Lens group G6 is the lens group disposed closest to the image side. Here, the widest interval during infinity focusing is the air interval between the fourth lens group G4 and the fifth lens group G5. The configuration of each lens group will be described below.

First lens group G1: The first lens group G1, which is a fixed lens group, includes, in order from the object side, an object-side convex meniscus lens L1 having negative refractive power, a biconvex lens L2 having positive refractive power, It is composed of a cemented lens that is a combination of a biconvex lens L3 having a positive refractive power and a biconcave lens L4 having a negative refractive power. In order to perform image stabilization when camera shake occurs, the biconvex lens L2 included in the first lens group is used as an image stabilizing group that moves in a direction perpendicular to the optical axis to shift the image.

Second lens group G2: The second lens group G2 is composed only of a biconcave lens L5 having negative refractive power.

Third lens group G3: The third lens group G3 is composed of a cemented lens that combines, in order from the object side, a biconvex lens L6 having a positive refractive power and a biconcave lens L7 having a negative refractive power.

Fourth lens group G4: The fourth lens group G4 is a cemented lens that combines, in order from the object side, a biconvex lens L8 having a positive refractive power and a meniscus lens L9 having a concave shape on the object side and having a negative refractive power. It consists of

Fifth lens group G5: The fifth lens group G5 is composed of a cemented lens in which a biconvex lens L10 having a positive refractive power and a biconcave lens L11 having a negative refractive power are cemented.

Sixth lens group G6: The sixth lens group G6 is composed of a biconcave lens L12 having negative refractive power.

(2) Numerical Example A numerical example to which specific numerical values of the photographic lens of Example 4 are applied will be described. Table 10 shows the surface data of the photographic lens. Table 11 shows the specifications of the photographic lens. Table 12 shows the focal length of each lens group constituting the photographic lens. Note that the 22nd surface and the 23rd surface in Table 10 are the surface data of the cover glass.

[Table 10]
No. RD Nd ABV
1 110.5279 1.0000 1.67764 32.17
2 42.1039 4.0000
3 90.5162 4.9302 1.45981 90.19
4 -74.8521 2.0000
5 40.0997 6.9972 1.77621 49.62
6 -49.8774 1.0000 1.73432 28.32
7 236.2476 3.0000
8S ∞ D(8)
9 -169.7833 1.0000 2.00912 29.13
10 55.7605 D(10)
11 109.7013 5.1592 2.01489 19.32
12 -30.1702 1.0000 1.96073 32.32
13 63.2597 D(13)
14 82.8709 8.2604 1.64129 55.45
15 -27.6948 1.0000 1.96073 32.32
16 -40.8485 D(16)
17 69.0729 5.7230 1.73234 54.67
18 -51.7087 1.0000 1.75918 25.05
19 15088.0499 D(19)
20 -39.6057 1.0000 1.91695 35.25
21 262.2522 19.0000
22 ∞ 2.5000 1.51872 64.20
23 ∞ 1.0000

[Table 11]
Infinity β = 1.01
F 87.3000 35.9189
Fno 2.8804 5.7895
ω 13.4461 9.8276
Shooting distance ∞ 100.4310
D( 8) 2.0164 19.7371
D(10) 2.3148 5.8355
D(13) 22.9629 1.7215
D(16) 33.7311 0.0000
D(19) 4.4048 38.1359

[Table 12]
Group Surface number Focal length
G1 1-8 50.09
G2 9-10 -41.50
G3 11-13 -267.50
G4 14-16 51.82
G5 17-19 99.47
G6 20-21 -37.47

Further, FIGS. 11 and 12 show longitudinal aberration diagrams of the photographing lens of Example 4 when focusing on infinity and when focusing on close distance, respectively.

(1) Optical configuration of photographic lens FIG. 13 is a lens cross-sectional view showing the lens configuration of the photographic lens of Example 5 according to the present invention when focusing on infinity. This photographic lens includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a third lens group G3 having a positive refractive power. The fourth lens group G4 has a negative refractive power, the fifth lens group G5 has a negative refractive power, and the sixth lens group G6 has a negative refractive power. When focusing from an object at infinity to a nearby object, the second lens group having negative refractive power moves from the object side to the image side along the optical axis. When focusing from an object at infinity to a nearby object, the fourth lens group having positive refractive power moves from the image side to the object side along the optical axis. When focusing from an object at infinity to a nearby object, the fifth lens group, which has negative refractive power, first moves from the image side to the object side along the optical axis, and then moves from the object side to the image side along the optical axis. Reverse direction and move. The aperture stop S is arranged on the image side of the first lens group G1.

In Example 5, the first lens group G1 having a positive refractive power is a fixed lens group, the second lens group G2 having a negative refractive power is a first focus lens group, and the third lens group having a positive refractive power. G3 is an additional lens group, the fourth lens group G4 having a positive refractive power is an additional lens group, the fifth lens group G5 is a second focus lens group having a negative refractive power, and the sixth lens group has a negative refractive power. Lens group G6 is the lens group disposed closest to the image side. Here, the widest interval during infinity focusing is the air interval between the third lens group G3 and the fourth lens group G4. The configuration of each lens group will be described below.

First lens group G1: The first lens group G1, which is a fixed lens group, includes, in order from the object side, an object-side convex meniscus lens L1 having negative refractive power, a biconvex lens L2 having positive refractive power, It is composed of a cemented lens that is a combination of a biconvex lens L3 having a positive refractive power and a biconcave lens L4 having a negative refractive power. In order to perform image stabilization when camera shake occurs, the biconvex lens L2 included in the first lens group is used as an image stabilizing group that moves in a direction perpendicular to the optical axis to shift the image.

Second lens group G2: The second lens group G2 includes, in order from the object side, a double-concave lens L5, a double-concave lens L6 having a positive refractive power, and a double-concave lens L7 having a negative refractive power. It consists of

Third lens group G3: The third lens group G3 is a cemented lens that combines, in order from the object side, a biconvex lens L8 with positive refractive power and a concave meniscus lens L9 on the object side with negative refractive power. It consists of

Fourth lens group G4: The fourth lens group G4 is a cemented lens that combines, in order from the object side, a biconvex lens L10 with positive refractive power and a meniscus lens L11 with negative refractive power and a concave shape on the object side. It consists of

Fifth lens group G5: The fifth lens group G5 is composed only of a meniscus lens L12 having a negative refractive power and having a concave shape on the object side.

Sixth lens group G6: The sixth lens group G6 is composed only of a meniscus lens L13 having a negative refractive power and having a concave shape on the object side.

(2) Numerical Example A numerical example to which specific numerical values of the photographic lens of Example 5 are applied will be described. Table 13 shows the surface data of the photographic lens. Table 14 shows the specifications of the photographic lens. Table 15 shows the focal length of each lens group constituting the photographic lens. Note that the 24th surface and the 25th surface in Table 13 are the surface data of the cover glass.

[Table 13]
No. RD Nd ABV
1 104.5246 1.0000 1.85505 23.78
2 46.5063 4.0000
3 99.4454 4.6757 1.45981 90.19
4 -72.6666 2.0000
5 41.9773 6.2685 1.73234 54.67
6 -66.6152 1.0000 1.72310 29.50
7 215.6351 3.0000
8S ∞ D(8)
9 -172.6808 1.0000 2.00912 29.13
10 44.5149 1.6887
11 50.2902 5.2367 2.01489 19.32
12 -51.7638 1.0000 1.96073 32.32
13 58.3943 D(13)
14 71.0902 7.8130 1.70559 41.15
15 -29.2793 1.0000 2.00996 25.46
16 -46.8332 D(16)
17 84.5974 4.6568 1.55206 75.50
18 -45.0269 1.0000 1.91695 35.25
19 -74.6890 D(19)
20 -40.9230 1.0000 1.73234 54.67
21 -92.5587 D(21)
22 -36.8988 1.0000 2.01489 19.32
23 -387.2291 19.0000
24 ∞ 2.5000 1.51872 64.20
25 ∞ 1.0000

[Table 14]
Infinite β= 1.01
F 87.2998 34.1392
Fno 2.8798 5.7893
ω 13.4082 9.2930
Shooting distance ∞ 107.4033
D( 8) 2.0488 27.4172
D(13) 27.0115 1.6431
D(16) 28.9434 0.0000
D(19) 4.1569 33.0870
D(21) 3.0000 3.0134

[Table 15]
Group Surface number Focal length
G1 1-8 60.43
G2 9-13 -41.83
G3 14-16 48.57
G4 17-19 94.11
G5 20-21 -100.99
G6 22-23 -40.24

Further, FIGS. 14 and 15 show longitudinal aberration diagrams of the photographing lens of Example 5 when focusing on infinity and when focusing on close distance, respectively.

(1) Optical configuration of photographic lens FIG. 16 is a lens cross-sectional view showing the lens configuration of the photographic lens of Example 6 according to the present invention when focusing on infinity. This photographic lens includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, and a third lens group G3 having a negative refractive power. It is composed of a fourth lens group G4 having the following. When focusing from an object at infinity to a nearby object, the second lens group with positive refractive power and the third lens group G3 with negative refractive power independently move from the object side to the image side along the optical axis. Moving. The aperture stop S is arranged in the first lens group G1.

In Example 6, the first lens group G1 having a positive refractive power is a fixed lens group, the second lens group G2 having a positive refractive power is a second focus lens group, and the third lens group having a negative refractive power. G3 is the first focus lens group, and the fourth lens group G4 having negative refractive power is the lens group disposed closest to the image side. Here, the widest interval during infinity focusing is the air interval between the first lens group G1 and the second lens group G2. The configuration of each lens group will be described below.

First lens group G1: The first lens group G1, which is a fixed lens group, includes, in order from the object side, an object-side convex meniscus lens L1 having negative refractive power, a biconvex lens L2 having positive refractive power, It is composed of an aperture stop S and a cemented lens that is a combination of an object-side concave meniscus lens L3 having positive refractive power and an object-side concave meniscus lens L4 having negative refractive power. In order to perform image stabilization when camera shake occurs, the biconvex lens L2 included in the first lens group is used as an image stabilizing group that shifts the image by moving in a direction perpendicular to the optical axis.

Second lens group G2: The second lens group G2 includes, in order from the object side, an object-side convex meniscus lens L5 having positive refractive power, an object-side convex meniscus lens L6 having negative refractive power, and a positive refractive power. It is composed of a cemented lens combined with a meniscus lens L7 having a convex shape on the object side and having a refractive power of .

Third lens group G3: The third lens group G3 is composed of a cemented lens that combines, in order from the object side, a biconvex lens L8 having a positive refractive power and a biconcave lens L9 having a negative refractive power.

Fourth lens group G4: The fourth lens group G4 is a cemented lens that combines, in order from the object side, a meniscus lens L10 with a concave shape on the object side having a negative refractive power and a biconvex lens L11 having a positive refractive power. It consists of

(2) Numerical Example A numerical example to which specific numerical values of the photographic lens of Example 6 are applied will be described. Table 16 shows the surface data of the photographic lens. Table 17 shows the specifications of the photographic lens. Table 18 shows the focal length of each lens group constituting the photographic lens. Note that the 21st surface and the 22nd surface in Table 16 are the surface data of the cover glass.

[Table 16]
No. RD Nd ABV
1 50.0329 1.0000 1.77621 49.62
2 28.7291 5.0000
3 67.3330 4.5000 1.45981 90.19
4 -134.1786 30.8668
5S ∞ 3.0201
6 -122.5812 9.3254 1.62555 58.12
7 -25.1619 2.0000 1.90615 37.37
8 -33.7642 D( 8)
9 39.1264 3.0346 2.01489 19.32
10 57.4556 2.7615
11 51.9769 1.0000 2.00996 25.46
12 22.0695 6.9774 1.73234 54.67
13 132.2750 D(13)
14 224.9047 3.9557 2.01489 19.32
15 -55.5601 1.0000 2.00996 25.46
16 47.2352 D(16)
17 -28.4271 1.0000 2.00912 29.13
18 -75.3660 0.0000
19 217.5290 2.7822 2.01489 19.32
20 -212.0384 19.0000
21 ∞ 2.5000 1.51872 64.20
22 ∞ 1.0000

[Table 17]
Infinity β= 0.50
F 92.7000 58.4491
Fno 2.8969 4.3203
ω 12.9931 10.3083
Shooting distance ∞ 195.7775
D( 8) 38.8869 0.0000
D(13) 3.0000 10.9584
D(16) 7.3892 38.3177

[Table 18]
Group Surface number Focal length
G1 1-8 83.56
G2 9-13 92.70
G3 14-16 -60.45
G4 17-20 -82.37

Further, FIGS. 17 and 18 show longitudinal aberration diagrams of the photographing lens of Example 6 when focusing on infinity and when focusing on close distance, respectively.

(1) Optical configuration of photographic lens FIG. 19 is a lens cross-sectional view showing the lens configuration of the photographic lens of Example 7 according to the present invention when focusing on infinity. This photographic lens includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, and a third lens group G3 having a negative refractive power. It is composed of a fourth lens group G4 having the following. When focusing from an object at infinity to a nearby object, the second lens group with positive refractive power and the third lens group G3 with negative refractive power independently move from the object side to the image side along the optical axis. Moving. The aperture stop S is arranged in the first lens group G1.

In Example 7, the first lens group G1 having a positive refractive power is a fixed lens group, the second lens group G2 having a positive refractive power is a first focus lens group, and the third lens group having a negative refractive power. G3 is the second focus lens group, and the fourth lens group G4 having negative refractive power is the lens group disposed closest to the image side. Here, the widest interval during infinity focusing is the air interval between the first lens group G1 and the second lens group G2. The configuration of each lens group will be described below.

First lens group G1: The first lens group G1, which is a fixed lens group, includes, in order from the object side, a meniscus lens L1 having a negative refractive power and a convex shape on the object side, and a meniscus lens L1 having a convex shape on the object side having a positive refractive power. It is composed of a meniscus lens L2, an aperture stop S, and a cemented lens that is a combination of a meniscus lens L3 having a positive refractive power and a concave shape on the object side and a meniscus lens L4 having a negative refractive power and a concave shape on the object side. There is. In order to perform image stabilization when camera shake occurs, the biconvex lens L2 included in the first lens group is used as an image stabilizing group that moves in a direction perpendicular to the optical axis to shift the image.

Second lens group G2: The second lens group G2 includes, in order from the object side, an object-side convex meniscus lens L5 having negative refractive power, an object-side convex meniscus lens L6 having negative refractive power, and a positive It is composed of a cemented lens combined with a meniscus lens L7 having a convex shape on the object side and having a refractive power of .

Third lens group G3: The third lens group G3 is composed of a cemented lens that combines, in order from the object side, a biconcave lens L8 having a negative refractive power and a biconvex lens L9 having a positive refractive power.

Fourth lens group G4: The fourth lens group G4 includes, in order from the object side, a biconcave lens L10 having a negative refractive power and a biconvex lens L11 having a positive refractive power.

(2) Numerical Example A numerical example to which specific numerical values of the photographic lens of Example 7 are applied will be described. Table 19 shows the surface data of the photographic lens. Table 20 shows the specifications of the photographic lens. Table 21 shows the focal length of each lens group constituting the photographic lens. Note that the 21st surface and the 22nd surface in Table 19 are the surface data of the cover glass.

[Table 19]
No. RD Nd ABV
1 33.6848 1.0000 1.92963 22.94
2 28.9727 9.9309
3 83.1573 4.5000 1.73234 54.67
4 4924.6429 21.5132
5S ∞ 7.7576
6 -57.8216 6.5995 1.54572 52.52
7 -27.7581 2.0000 1.91694 35.25
8 -33.4549 D(8)
9 20.6528 1.9557 1.92705 24.68
10 20.6210 2.7892
11 24.8612 1.0000 1.91694 35.25
12 17.3803 6.8589 1.53548 73.75
13 125.9159 D(13)
14 -83.5535 1.5000 1.91694 35.25
15 24.4372 10.0000 1.64604 33.32
16 -49.0700 D(16)
17 -36.5684 1.0000 1.86636 38.42
18 66.0874 1.5653
19 75.9794 3.2545 1.93325 20.88
20 -609.5108 16.0000
21 ∞ 2.5000 1.51872 64.20
22 ∞ 1.0000

[Table 20]
Infinity β= 0.50
F 117.3000 58.1457
Fno 2.8766 4.3150
ω 10.0403 9.1163
Shooting distance ∞ 222.2932
D( 8) 40.9643 2.0000
D(13) 3.6432 3.6428
D(16) 2.6677 41.6325

[Table 21]
Group Surface number Focal length
G1 1-8 105.36
G2 9-13 77.31
G3 14-16 -140.76
G4 17-20 -45.21

Further, FIGS. 20 and 21 show longitudinal aberration diagrams of the photographing lens of Example 7 when focusing on infinity and when focusing on close distance, respectively.

[Table 22]
Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7
Conditional expression (1) -0.76 -0.17 -0.89 -0.79 -0.87 -0.89 -0.70
Conditional expression (2) 0.60 0.39 0.41 0.57 0.69 0.90 0.90
Conditional expression (3) 1.29 1.26 1.41 1.23 1.42 1.11 1.11
Conditional expression (4) 0.32 0.19 0.23 0.39 0.33 0.42 0.35
Conditional expression (5) -0.36 -0.18 -0.43 -0.43 -0.46 -0.89 -0.39
Conditional expression (6) 2.73 6.57 5.68 1.91 1.27 1.65 2.48
Conditional expression (7) 0.47 0.19 0.30 0.48 0.48 0.65 0.66
Conditional expression (8) 0.98 0.46 0.75 1.14 1.16 1.00 1.20
Conditional expression (9) 0.19 0.32 0.27 0.20 0.20 0.32 0.28
Conditional expression (10) 0.45 0.39 0.22 0.65 0.60 0.55 0.60
Conditional expression (11) 1.01 1.01 1.01 1.01 1.01 0.50 0.50

By adopting the above-mentioned lens arrangement and refractive power arrangement of the optical system, the photographic lens according to this application can satisfactorily correct various aberrations from infinity to close range, shorten the total optical length, and achieve compact photography. We can provide lenses. Therefore, it becomes easy to reduce the size and weight of an imaging device using this photographic lens.

G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group G5 Fifth lens group G6 Sixth lens group S Aperture stop IP Image plane

Claims (13)

A photographic lens including a fixed lens group closest to the object side , and at least a first focus lens group and a second focus lens group on the image side of the fixed lens group,
The fixed lens group is a lens group whose position in the optical axis direction does not change during focusing,
an aperture stop whose position is fixed with respect to the image plane within the fixed lens group or between the fixed lens group and a lens group on the image side adjacent to the fixed lens group;
At least the first focus lens group and the second focus lens group are moved by different amounts of movement along the optical axis to perform focusing in a range from infinity to close distance,
The first focus lens group is a lens group that has the smallest absolute value of focal length among the lens groups that move along the optical axis when focusing from infinity to close range,
A photographic lens characterized by satisfying the following conditional expression.
-0.90 ≦ fr/f ≦ -0.05 (1)
1.65≦｜(1-βfo1 ² )×βfor ² |≦15.0 ・・・(6)'
however,
fr: Combined focal length of lens groups excluding fixed lens groups f: Focal length at infinity focus
βfo1: Lateral magnification of the first focus lens group when focusing at infinity
βfor: Composite lateral magnification at infinity focusing of lenses placed closer to the image side than the first focus lens group A photographic lens including a fixed lens group closest to the object side, and at least a first focus lens group and a second focus lens group on the image side of the fixed lens group,
The fixed lens group is a lens group whose position in the optical axis direction does not change during focusing,
an aperture stop whose position is fixed with respect to the image plane within the fixed lens group or between the fixed lens group and a lens group on the image side adjacent to the fixed lens group;
At least the first focus lens group and the second focus lens group are moved by different amounts of movement along the optical axis to perform focusing in a range from infinity to close distance,
The first focus lens group is a lens group that has the smallest absolute value of focal length among the lens groups that move along the optical axis when focusing from infinity to close range,
A photographic lens characterized by satisfying the following conditional expression.
0.05 ≦ f1/f ≦0.70 (2)
0.05 ≦ | ffo1 /f | ≦ 0.80 ... (7)'
however,
f1: Focal length of fixed lens group
f: Focal length at infinity focus
ffo1: Focal length of the first focus lens group A photographic lens including a fixed lens group closest to the object side, and at least a first focus lens group and a second focus lens group on the image side of the fixed lens group,
The fixed lens group is a lens group whose position in the optical axis direction does not change during focusing,
an aperture stop whose position is fixed with respect to the image plane within the fixed lens group or between the fixed lens group and a lens group on the image side adjacent to the fixed lens group;
At least the first focus lens group and the second focus lens group are moved by different amounts of movement along the optical axis to perform focusing in a range from infinity to close distance,
The first focus lens group is a lens group that has the smallest absolute value of focal length among the lens groups that move along the optical axis when focusing from infinity to close range,
A photographic lens characterized by satisfying the following conditional expression.
0.05 ≦ f1/f ≦0.70 (2)
1.65≦|(1-βfo1 ² )×βfor ² ｜≦15.0...(6)'
however,
f1: Focal length of fixed lens group
f: Focal length at infinity focus
βfo1: Lateral magnification of the first focus lens group when focusing at infinity
βfor: Composite lateral magnification at infinity focusing of lenses placed closer to the image side than the first focus lens group The photographic lens according to claim 1, which satisfies the following conditional expression.
0.05 ≦ f1/f ≦0.95 (2)'
however,
f1: Focal length of fixed lens group
f: Focal length at infinity focus A front lens group having a positive refractive power on the object side and a rear lens group having a negative refractive power on the image side, with the point where the air gap is the widest when focusing on infinity as the boundary, and the following conditional expression is satisfied. The photographing lens according to any one of claims 1 to 4 .
1.0 ≦ βr1 (3)
0.15≦CT/f≦1.00 (4)
however,
βr1: Lateral magnification of the rear lens group when focusing at infinity
CT: Distance between front lens group and rear lens group The photographing lens according to any one of claims 1 to 5, which satisfies the following conditional expressions.
-1.00 ≦ fn/f ≦ -0.05 (5)
however,
fn: Focal length of the lens group located closest to the image side The first focus lens group is a lens group that has the smallest absolute value of focal length among the lens groups that move along the optical axis when focusing from infinity to close range,
The photographic lens according to claim 2, which satisfies the following conditional expression.
1.2≦｜(1−βfo1 ² )×βfor ² |≦15.0 (6)
however,
βfo1: Lateral magnification of the first focus lens group when focusing on infinity βfor: Composite lateral magnification when focusing on infinity of lenses placed closer to the image side than the first focus lens group The first focus lens group is a lens group that has the smallest absolute value of focal length among the lens groups that move along the optical axis when focusing from infinity to close range,
The photographic lens according to claim 1 or 3, which satisfies the following conditional expression.
0.05 ≦ | ffo1 /f | ≦ 1.20 (7)
however,
ffo1: Focal length of the first focus lens group The first focus lens group is a lens group that has the smallest absolute value of focal length among the lens groups that move along the optical axis when focusing from infinity to close range,
The second focus lens group is a lens group with the smallest absolute value of focal length among the lens groups that move along the optical axis when focusing from infinity to close range, excluding the first focus lens group,
The photographing lens according to any one of claims 1 to 8, which satisfies the following conditional expressions.
0.05 ≦ | ffo2/f | ≦ 1.20 (8)
however,
ffo2: Focal length of the second focus lens group The photographing lens according to any one of claims 1 to 9, which satisfies the following conditional expressions.
Ls/L≦0.70 (9)
however,
Ls: Distance from the lens surface closest to the object side to the aperture stop L: Distance from the lens surface closest to the object side to the lens surface closest to the image side The photographic lens according to any one of claims 1 to 10, which satisfies the following conditional expressions.
0.10≦Lf/L≦0.80 (10)
however,
Lf: Total amount of movement of each focus lens group from infinity focusing to close focusing L: Distance from the lens surface closest to the object side to the lens surface closest to the image side The photographic lens according to any one of claims 1 to 11, which satisfies the following conditional expressions.
0.5 ≦ |β| ...(11)
however,
β: Maximum imaging magnification The photographic lens according to any one of claims 1 to 12 is provided, and an image sensor that converts an optical image formed by the photographic lens into an electrical signal on the image plane side of the photographic lens. An imaging device characterized by:

Images