JP6546401B2 - Telephoto lens and imaging device having the same - Google Patents

Description

  The present invention relates to a telephoto lens and an imaging device having the same. In particular, the present invention relates to a telephoto lens suitable for interchangeable lens system applications.

In recent years, with the development of digital cameras, various interchangeable lenses for digital cameras have been proposed. For example, in Patent Document 1, in the positive / negative / positive three-group configuration, the stop is disposed on the most image side of the first group, and focusing on a near distance object point is performed by the movement of the second group. This configuration realizes a 300 mm / F4 telephoto lens for interchangeable lenses.
Further, for example, in Patent Document 2, in the positive / negative / positive three-group configuration, focusing is performed by movement of the second group, and the stop is disposed in the third group. This configuration realizes a telephoto lens of 400 mm / F 2.8 to 800 mm / F 5.6 for interchangeable lenses.

Japanese Patent Application Publication No. 2007-322986 JP, 2013-250293, A

  However, in the configurations of Patent Document 1 and Patent Document 2, it is difficult to achieve both the reduction in diameter of the optical system and the correction of various aberrations.

  The present invention is made in view of the above, and an object of the present invention is to provide an imaging device in which the diameter reduction of an optical system is achieved and the occurrence of various aberrations is well suppressed.

In order to solve the problems described above and achieve the purpose, the telephoto lens of the present invention is
In order from the object side to the image side,
A first lens unit having a fixed position and a positive refractive power,
A second lens unit of negative refractive power that moves to the image side along the optical axis during focusing from an infinite object point to a near object point;
When focusing, the position in the optical axis direction consists of a fixed positive power rear lens group,
The rear lens group includes a third lens group having a fixed position and a positive refractive power, a fourth lens group having a negative refractive power, which is a camera shake reduction lens moving in a direction perpendicular to the optical axis, and a positive lens having a fixed position. And the fifth lens group,
The fifth lens group includes, in order from the object side to the image side, possess the object side cemented lens, and the image side cemented lens, and
Each of the object-side cemented lens and the image-side cemented lens has a positive lens and a negative lens,
It is characterized by satisfying the following conditional expression (8) .
0.60 <θgF _G5min <0.68 (8)
here,
θgF _G5min is the smallest θgF of the negative lenses in the fifth lens group, θgF,
θ _gF is a partial dispersion ratio, and is expressed by θ _gF = (ng−nF) / (nF−nC)
nC, nF, ng are the refractive index to C line, F line, g line, respectively
It is.

  An imaging apparatus according to the present invention is characterized by including the above-described telephoto lens, and an imaging element having an imaging surface and converting an image formed on the imaging surface by the telephoto lens into an electrical signal.

  The present invention achieves the effect of being able to provide a telephoto lens in which occurrence of various aberrations is well suppressed and an image pickup apparatus having the same, while achieving a reduction in the diameter of the optical system.

FIG. 6A is a cross-sectional view of the telephoto lens at the time of infinite object point focusing of the first embodiment; FIG. 7B is a lens cross-sectional view of the telephoto lens at the time of infinite object point focusing of the second embodiment. FIG. 7A is a cross-sectional view of the telephoto lens of Embodiment 3 when focusing on an infinite object point. FIG. 18B is a lens sectional view at the time of infinity object point focusing of the telephoto lens according to Example 4. FIG. 16A is a lens sectional view at the time of infinite object point focusing of a telephoto lens according to Example 5; FIG. 16B is a lens sectional view at the time of infinity object point focusing of the telephoto lens according to Example 6. (A) to (d) show spherical aberration (SA), astigmatism (AS), distortion (DT) and lateral chromatic aberration (CC) at the time of infinite object point focusing of the telephoto lens according to Example 1. FIG. (E) to (h) show spherical aberration (SA), astigmatism (AS), distortion (DT) and lateral chromatic aberration (CC) at the time of infinite object point focusing of the telephoto lens according to Example 2. FIG. (A) to (d) show spherical aberration (SA), astigmatism (AS), distortion (DT) and lateral chromatic aberration (CC) at the time of infinite object point focusing of the telephoto lens according to Example 3. FIG. (E) to (h) show spherical aberration (SA), astigmatism (AS), distortion (DT) and lateral chromatic aberration (CC) at the time of infinite object point focusing of the telephoto lens according to Example 4. FIG. (A) to (d) show spherical aberration (SA), astigmatism (AS), distortion (DT) and lateral chromatic aberration (CC) at the time of infinite object point focusing of the telephoto lens according to Example 5. FIG. (E) to (h) show spherical aberration (SA), astigmatism (AS), distortion (DT) and lateral chromatic aberration (CC) at the time of infinite object point focusing of the telephoto lens according to Example 6. FIG. It is a sectional view of an imaging device. It is a front perspective view of an imaging device. It is a rear perspective view of an imaging device. FIG. 2 is a configuration block diagram of an internal circuit of a main part of the imaging device.

  Prior to the description of the examples, the operation and effects of the embodiment according to an aspect of the present invention will be described. In addition, when demonstrating the effect of this embodiment concretely, a specific example is shown and demonstrated. However, as in the case of the examples described later, those exemplified aspects are only some of the aspects included in the present invention, and there are many variations in the aspects. Accordingly, the present invention is not limited to the illustrated embodiments.

  The telephoto lens of the present embodiment includes, in order from the object side to the image side, a first lens group of positive refracting power, a second lens group of negative refracting power, and a rear lens group of positive refracting power. Has a third lens group of positive refracting power, a fourth lens group of negative refracting power, and a fifth lens group of positive refracting power, and the fifth lens group is arranged in order from the object side to the image side An object side cemented lens and an image side cemented lens are characterized by having.

  In order to reduce the overall length of the entire optical system, it is preferable to make the optical system of the telephoto type. In the telephoto lens of this embodiment, the first lens group having positive refracting power and the second lens group having negative refracting power are disposed in this order from the object side to the image side, so that the optical system has a telephoto type configuration. Will be included. Therefore, the entire lens length can be shortened.

  Further, on the image side of the second lens group, a rear lens group of positive refractive power is disposed. By doing this, it is possible to suppress the occurrence of spherical aberration, coma and astigmatism by the rear lens group.

  In addition, when the third lens group has a positive refracting power, it is possible to cause the third lens group to converge the light beam that has passed through the first lens group and the second lens group. As a result, the luminous flux incident on the fourth lens group can be reduced, so it becomes easy to reduce the diameter of the lens in the fourth lens group. Further, by making the fifth lens group have a positive refractive power, it is possible to increase the negative refractive power of the fourth lens group.

  As described above, by setting the arrangement of refractive power in the rear lens group to positive refractive power, negative refractive power, or positive refractive power, the Petzval sum can be made favorable. As a result, the occurrence of astigmatism can be suppressed.

  In addition, the fifth lens unit is disposed near the image plane. Therefore, when the fifth lens group includes two cemented lenses, the refractive power of the fifth lens group can be increased. This makes it possible to correct the lateral chromatic aberration effectively while making the Petzval sum good and at the same time minimizing the influence on the axial chromatic aberration.

  In the telephoto lens of the present embodiment, it is preferable that the first lens group has a first sub lens unit and a second sub lens unit in order from the object side to the image side.

  In addition, when the first lens group includes the first sub lens unit and the second sub lens unit, generation of spherical aberration and chromatic aberration can be suppressed by the two sub lens units.

Moreover, it is preferable that the telephoto lens of this embodiment satisfies the following conditional expression (1).
0.4 <d _su1o2 / d _G1 <0.8 (1)
here,
d _{su1 o} 2 is the distance on the optical axis from the object-side surface of the lens located closest to the object side of the first sub-lens unit to the object-side surface of the lens located closest to the object side of the second sub-lens unit
d _G1 is the distance on the optical axis from the object-side surface of the lens located closest to the object side of the first lens group to the image-side surface of the lens located closest to the image of the first lens group,
It is.

  Conditional expression (1) relates to the lens diameter of the second sub lens unit.

By less than the upper limit value of conditional expression (1), while ensuring the appropriate lens diameter in the second sub lens unit, the height of the ray incident on the second sub-lens unit, it is possible to some extent high. Thereby, generation | occurrence | production of an aberration can be suppressed by the 2nd sub lens unit. In addition, since the occurrence of aberration can be sufficiently suppressed by the second sub lens unit, the number of lenses in the first sub lens unit can be reduced. Alternatively, it is not necessary to reduce the refractive power of the first sub lens unit. As a result, the overall length and weight of the entire optical system can be reduced.

By exceeding the lower limit value, the on-axis distance between the first sub lens unit and the second sub lens unit can be appropriately secured. In this case, since the height of the ray incident on the second sub lens unit is lowered, it is possible to reduce the lens diameter of the second sub lens unit.

Moreover, it is preferable that the telephoto lens of this embodiment satisfies the following conditional expression (2).
0.4 <f _su1 /f<1.0 (2)
here,
f _su1 is the focal length of the first sub-lens unit,
f is the focal length of the entire telephoto lens system when focusing on an infinite object point,
It is.

  Conditional expression (2) relates to the refractive power of the first sub lens unit.

  By falling below the upper limit value of the conditional expression (2), the refractive power of the first sub lens unit becomes large. As a result, the height of the light beam incident on the second sub lens unit can be reduced, so that the second sub lens unit can be reduced in size and weight. In addition, the entire lens can be reduced in size and weight.

  By exceeding the lower limit value of the conditional expression (2), it is possible to reduce the refractive power of the first sub lens unit, so it is possible to suppress the occurrence of high-order spherical aberration.

Moreover, it is preferable that the telephoto lens of this embodiment satisfies the following conditional expression (3).
4 <f _su1 / d _su1i2 <15 (3)
here,
f _su1 is the focal length of the first sub-lens unit,
d _{su1 i2} is the distance on the optical axis from the image-side surface of the lens located closest to the image side of the first sub-lens unit to the object-side surface of the lens located closest to the object side of the second sub-lens unit
It is.

  By being smaller than the upper limit value of the conditional expression (3), the height of the light beam incident on the second sub lens unit can be reduced, so that the second sub lens unit can be reduced in size and weight. In addition, the entire lens can be reduced in size and weight.

By exceeding the lower limit value of the conditional expression (3), the height of the light beam incident on the second sub lens unit can be increased to a certain extent. Therefore, various aberrations generated in the first sub lens unit can be reduced by the second sub lens unit.

  Further, in the telephoto lens of the present embodiment, it is preferable that the first lens group has a third sub lens unit on the image side of the second sub lens unit.

  In this way, residual aberration (second-order spectrum), that is, aberration that can not be corrected by the first sub lens unit and the second sub lens unit can be corrected well by the third sub lens unit. it can.

  Further, in the telephoto lens of the present embodiment, it is preferable that both the refractive power of the first sub lens unit and the refractive power of the third sub lens unit be positive refractive power.

  As described above, by making the configuration of the optical system a telephoto type configuration, the effect of shortening the overall length of the optical system can be obtained. This action can be increased by increasing the positive refractive power of the first lens group. As a result, the entire length of the entire optical system can be shortened.

  By making both the refractive power of the first sub lens unit and the refractive power of the third sub lens unit positive, the positive refractive power in the first lens group can be shared by the two sub lens units. Therefore, the occurrence of aberration can be suppressed even if the positive refractive power of the first lens group is increased. As a result, it is possible to maintain good imaging performance of the optical system while reducing the overall length of the entire optical system.

Further, in the telephoto lens of the present embodiment, it is preferable that the third sub lens unit have at least one positive lens satisfying the following conditional expression (4).
16 < _{su su3pmin} <55 (4)
here,
_{su su3pmin} is the Abbe number which is the smallest among the Abbe numbers of the positive lens in the third sub lens unit,
It is.

  By exceeding the upper limit value of the conditional expression (4), it is possible to dispose a high dispersion positive lens in the third sub lens unit. Since the high dispersion glass material has a large θgF (partial dispersion ratio), θgF of the positive lens can be increased in the third sub lens unit. As a result, residual aberration (secondary spectrum), that is, aberration which can not be corrected by the first sub lens unit and the second sub lens unit can be corrected well by the third sub lens unit.

  By exceeding the lower limit value of the conditional expression (4), selection of the glass material used for the positive lens can be facilitated.

Moreover, it is preferable that the telephoto lens of this embodiment satisfies the following conditional expression (5).
0.35 <f _su3 / f <1 (5)
here,
f _su3 is the focal length of the third sub-lens unit,
f is the focal length of the entire telephoto lens system when focusing on an infinite object point,
It is.

  By falling below the upper limit value of the conditional expression (5), it is possible to sufficiently ensure the positive refractive power in the first lens group. By exceeding the lower limit value of the conditional expression (5), it is possible to suppress the aberration generated in the third sub lens unit.

  Further, in the telephoto lens of the present embodiment, it is preferable that the first sub lens unit be composed of one or two single lenses.

  If the number of lenses in the first sub lens unit increases, the weight of the entire optical system increases and the cost also increases, which is not preferable. By configuring the first sub lens unit with one or two single lenses, weight reduction and cost reduction of the entire optical system can be performed.

  In the telephoto lens of the present embodiment, the second sub lens unit preferably includes, in order from the object side to the image side, a negative lens, a positive lens, a positive lens, and a negative lens.

  The second sub lens unit mainly corrects spherical aberration and chromatic aberration generated in the first sub lens unit. By disposing the negative lens and the positive lens in the second sub lens unit, various aberrations, in particular, spherical aberration and chromatic aberration can be favorably corrected without significantly reducing the positive refractive power of the entire first lens group.

  Moreover, in the telephoto lens of the present embodiment, it is preferable that the second sub lens unit have a cemented lens on the most object side.

  By arranging the cemented lens, it is possible to obtain a large correction effect on the chromatic aberration while keeping the air contact surface the same number of surfaces as the single lens. Thus, the arrangement of the cemented lens is advantageous for chromatic aberration correction.

  Further, in the telephoto lens of the present embodiment, the second sub lens unit preferably includes an object side cemented lens and an image side cemented lens in order from the object side to the image side.

  As described above, by arranging the cemented lens, it is possible to obtain a large correction effect on the chromatic aberration while keeping the air contact surface the same number of surfaces as the single lens. By arranging the two cemented lenses, it is possible to obtain a larger effect of chromatic aberration correction, and therefore it is possible to correct the chromatic aberration even better.

  Further, in the telephoto lens of the present embodiment, the object-side cemented lens of the second sub lens unit includes, in order from the object side to the image side, a negative single lens and a positive single lens, and the second sub lens unit The image-side cemented lens preferably comprises, in order from the object side to the image side, a positive single lens and a negative single lens.

Further, in the telephoto lens of the present embodiment, it is preferable that the third sub lens unit be composed of one lens component.
Here, the lens component is a single lens or a cemented lens, and is a lens having two optically effective surfaces in air contact.

  The third sub lens unit mainly corrects axial chromatic aberration. Therefore, the third sub lens unit can be configured of one lens component. Also in the case where the third sub lens unit is given positive refracting power, it is possible to secure sufficient refracting power with one lens component.

  By using a cemented lens as a lens component, spherical aberration can be corrected well.

Moreover, it is preferable that the telephoto lens of this embodiment satisfies the following conditional expression (6).
0.42 <d _G1 / L _TL <0.52 (6)
here,
d _G1 is the distance on the optical axis from the object-side surface of the lens located closest to the object side of the first lens group to the image-side surface of the lens located closest to the image of the first lens group,
L _TL is the distance from the object side surface of the lens located closest to the object side of the telephoto lens to the image plane when focusing on an infinite object point;
It is.

Below the upper limit value of the conditional expression (6), the total length of the optical system can be shortened. By exceeding the lower limit value of the conditional expression (6), the size of the first lens unit in the radial direction can be reduced. L _TL is a distance when not converted to air.

Moreover, it is preferable that the telephoto lens of this embodiment satisfies the following conditional expression (7).
1 <d _su1s / d _G1 <1.2 (7)
here,
d _su1s is the distance on the optical axis from the object side surface of the lens located closest to the object side of the first sub lens unit to the stop,
d _G1 is the distance on the optical axis from the object-side surface of the lens located closest to the object side of the first lens group to the image-side surface of the lens located closest to the image of the first lens group,
It is.

  By satisfying the conditional expression (7), the stop (aperture stop) is positioned between the first lens unit and the second lens unit. As a result, the mechanism (mechanism) for driving the stop can be simplified and the overall diameter of the optical system can be reduced.

Moreover, it is preferable that the telephoto lens of this embodiment satisfies the following conditional expression (8).
0.60 <θgF _G5min <0.68 (8)
here,
θgF _G5min is the smallest θgF of the negative lenses in the fifth lens group, θgF,
θ _gF is a partial dispersion ratio, and is expressed by θ _gF = (ng−nF) / (nF−nC)
nC, nF, ng are the refractive index to C line, F line, g line, respectively
It is.

  In general, as the dispersion increases, the partial dispersion ratio also increases. By using a glass material having a particularly large dispersion, that is, a glass material having a particularly large partial dispersion ratio, for the negative lens of the fifth lens group, it becomes possible to satisfactorily correct the lateral chromatic aberration on the short wavelength side.

  By satisfying conditional expression (8), lateral chromatic aberration on the short wavelength side can be corrected well. In addition, in the case of using a glass material having a high refractive index and a high dispersion for the positive lens in the lens groups other than the fifth lens group, the range of choice is expanded. As a result, the overall size and weight of the optical system can be reduced.

  By exceeding the lower limit value of the conditional expression (8), it is possible to obtain a good achromatic effect (slope correction of C line and F line) and at the same time make the secondary spectrum smaller.

Moreover, it is preferable that the telephoto lens of this embodiment satisfies the following conditional expression (9).
0.05 ≦ f _G5 /f≦0.15 (9)
here,
f _G5 is the focal length of the fifth lens group,
f is the focal length of the entire telephoto lens system when focusing on an infinite object point,
Is

Below the upper limit value of the conditional expression (9), it is possible to appropriately secure the refractive power of the fifth lens unit. As a result, the overall length of the optical system can be shortened. By exceeding the lower limit value of the conditional expression (9), it is possible to suppress that the refractive power of the fifth lens group becomes too large. As a result, while suppressing the occurrence of aberration, it is possible to secure a back focus of an appropriate length.

Moreover, it is preferable that the telephoto lens of this embodiment satisfies the following conditional expression (10).
0.65 <L _TL /f<0.95 (10)
here,
L _TL is the distance from the object side surface of the lens located closest to the object side of the telephoto lens to the image plane when focusing on an infinite object point;
f is the focal length of the entire telephoto lens system when focusing on an infinite object point,
Is

  Below the upper limit value of the conditional expression (10), the total length of the optical system can be shortened. By exceeding the lower limit value of the conditional expression (10), it is possible to reduce the refractive power in each lens group. Therefore, the optical performance can be improved.

  Further, in the telephoto lens of the present embodiment, the object side cemented lens of the fifth lens group consists of, in order from the object side to the image side, a positive single lens and a negative single lens, and an image of the fifth lens group The side cemented lens preferably comprises, in order from the object side to the image side, a positive single lens and a negative single lens.

  By forming the fifth lens group with two cemented lenses, it is possible to increase the refractive power of the fifth lens group while suppressing the occurrence of field curvature, distortion and spherical aberration.

  Having a plurality of positive lenses in the fifth lens group is advantageous for correcting coma and chromatic aberration. In addition, in both the object-side cemented lens and the image-side cemented lens, the incident angle of off-axis light at the cemented surface is reduced by arranging a positive single lens and a negative single lens sequentially from the object side to the image side. be able to. Therefore, the occurrence of lateral chromatic aberration can be suppressed.

  Further, in the telephoto lens of the present embodiment, it is preferable that the fourth lens group have a camera shake reducing lens which moves in a direction perpendicular to the optical axis.

  As described above, by forming the fifth lens group by two cemented lenses, it is possible to intensify the refractive power of the fifth group. As a result, the amount of movement of the image when the fourth lens unit is decentered becomes large. That is, the camera shake sensitivity of the fourth lens group can be increased. Because of this, it is preferable to dispose a camera shake reduction lens in the fourth lens group.

  Further, in the telephoto lens of the present embodiment, it is preferable that a stop be disposed between the first lens group and the second lens group.

  By doing this, it is possible to simplify the mechanism (mechanism) for driving the stop and to reduce the diameter of the entire lens.

  In the telephoto lens of the present embodiment, it is preferable that the second lens unit move in the optical axis direction during focusing.

  In this way, focusing by the inner focusing method can be performed. By employing the inner focus system, the entire optical system can be miniaturized, and therefore, the focusing speed can be increased.

Further, in the telephoto lens of the present embodiment, it is preferable that the third lens group be composed of one lens component.
Here, the lens component is a single lens or a cemented lens, and is a lens having two optically effective surfaces in air contact.

  By optimizing the refractive powers and lens shapes of the other lens groups, the third lens group can be configured with the minimum number of lenses. By configuring the third lens group with one lens component, the entire optical system can be miniaturized.

Moreover, it is preferable that the telephoto lens of this embodiment satisfies the following conditional expression (11).
0.4 <f _G1 /f<0.5 (11)
here,
f _G1 is the focal length of the first lens group,
f is the focal length of the entire telephoto lens system when focusing on an infinite object point,
It is.

  By falling below the upper limit value of the conditional expression (11), it is possible to appropriately secure the refractive power of the first lens group. As a result, since the action by the configuration of the telephoto type can be easily obtained, the entire length of the optical system can be shortened. By exceeding the lower limit value of the conditional expression (11), the positive refractive power in the first lens unit does not become too large, so that the generation of high-order spherical aberration and axial chromatic aberration can be suppressed.

Moreover, it is preferable that the telephoto lens of this embodiment satisfies the following conditional expression (12).
−0.25 <f _G2 /f<−0.1 (12)
here,
f _G2 is the focal length of the second lens group,
f is the focal length of the entire telephoto lens system when focusing on an infinite object point,
It is.

  Below the upper limit value of the conditional expression (12), it is possible to appropriately secure the refractive power of the second lens unit. When focusing is performed by the second lens group, the refractive power of the second lens group can be increased. In this case, since the amount of movement of the second lens group at the time of focusing can be reduced, focusing can be performed at high speed.

  By exceeding the lower limit value of the conditional expression (12), the generation of spherical aberration can be suppressed.

Moreover, it is preferable that the telephoto lens of this embodiment satisfies the following conditional expression (13).
0.1 <f _G3 /f<0.3 (13)
here,
f _G3 is the focal length of the third lens group,
f is the focal length of the entire telephoto lens system when focusing on an infinite object point,
It is.

  In the third lens group, the rays passing through the first lens group and the second lens group are further converged by the positive refractive power. Thereby, the diameter reduction of the fourth lens group is facilitated.

  By falling below the upper limit value of the conditional expression (13), it is possible to increase the refractive power of the third lens group, and thus it is possible to further reduce the diameter of the fourth lens group. By exceeding the lower limit value of the conditional expression (13), it is possible to suppress the occurrence of spherical aberration and coma. In addition, since the number of lens components that make the third lens group highly correct can be reduced, the entire optical system can be miniaturized.

Moreover, it is preferable that the telephoto lens of this embodiment satisfies the following conditional expression (14).
−0.1 <f _G4 /f<−0.03 (14)
here,
f _G4 is the focal length of the fourth lens unit,
f is the focal length of the entire telephoto lens system when focusing on an infinite object point,
It is.

  By exceeding the lower limit value of the conditional expression (14), it is possible to increase the refractive power of the fourth lens group. As a result, the diameter of the fourth lens unit can be reduced. In addition, when the fourth lens group includes a camera shake reduction lens, it is possible to increase the blur correction sensitivity.

  By falling below the upper limit value of the conditional expression (14), it is possible to reduce the refractive power of the fourth lens group. As a result, it is possible to suppress the occurrence of various aberrations, in particular the occurrence of spherical aberration, coma and distortion.

  Further, in the telephoto lens of the present embodiment, it is preferable that the first lens group have a predetermined cemented lens.

  By having the cemented lens, a large correction effect can be obtained for the chromatic aberration. In addition, the assembly of the optical system becomes easy. When the second sub lens unit is configured of two cemented lenses, a predetermined cemented lens is the third cemented lens. In this case, the first lens group has three cemented lenses. Therefore, a larger correction effect can be obtained for the chromatic aberration.

Further, in the telephoto lens of the present embodiment, it is preferable that the object-side cemented lens of the second sub lens unit have at least one positive lens, and the following conditional expression (15) be satisfied.
85 <ν _sub2op <100 (15)
here,
sub _{sub2 op} is the Abbe number of at least one positive lens in the object side cemented lens of the second sub lens unit,
It is.

  In order to reduce the total length of the optical system, it is preferable to make the positive refractive power of the first lens unit as large as possible. Here, as a glass material of the positive lens in the object-side cemented lens of the second sub lens unit, it is preferable to select a glass material having small dispersion and anomalous dispersion.

  By satisfying conditional expression (15), it is possible to sufficiently obtain not only the first-order achromatizing effect in chromatic aberration but also the correction effect on the second-order spectrum even when the refractive power of the first lens group is large. it can.

  Below the upper limit value of the conditional expression (15), selection of the glass material used for the positive lens becomes easy. By exceeding the lower limit value of the conditional expression (15), the occurrence of chromatic aberration can be suppressed.

Further, in the telephoto lens of the present embodiment, it is preferable that the image-side cemented lens of the second sub lens unit has at least one positive lens and the following conditional expression (16) is satisfied.
70 <ν _sub2ip <100 (16)
here,
sub _sub2ip is the Abbe number of at least one positive lens in the image side cemented lens of the second sub lens unit,
It is.

  In order to reduce the total length of the optical system, it is preferable to make the positive refractive power of the first lens unit as large as possible. Here, as a glass material of the positive lens in the image side cemented lens of the second sub lens unit, it is preferable to select a glass material having small dispersion and anomalous dispersion.

  By satisfying conditional expression (16), it is possible to sufficiently obtain not only the first-order achromatizing effect in chromatic aberration but also the correction effect on the second-order spectrum even when the refractive power of the first lens group is large. it can.

  Below the upper limit value of the conditional expression (16), selection of the glass material used for the positive lens becomes easy. By exceeding the lower limit value of the conditional expression (16), the occurrence of chromatic aberration can be suppressed.

The telephoto lens according to the present embodiment includes, in order from the object side, a first group of positive refracting power, a second group of negative refracting power, and a third group of positive refracting power. It is characterized in that focusing from an infinite object point to a near object point is performed by moving to the image side, and the following conditional expression (17) is satisfied.
0.2 <Y ₂ / Y _1a <0.32 (17)
here,
Y ₂ is the maximum ray height of the on-axis ray at the entrance face of the second group,
Y _1a is the maximum ray height of the on-axis ray at the entrance face of the first group,
It is.

  Due to the length of the focal length of a telephoto lens, an increase in the lens diameter is inevitable. In particular, the incident light beam diameter is determined by the specifications of the telephoto lens. For this reason, it is necessary to secure the necessary size according to the specification. The telephoto lens of this embodiment is composed of three groups of positive, negative and positive, and focusing is performed by the second group. Usually, in this configuration, the diameter of the second group tends to be large, the weight of the focus group becomes large, and high-speed driving becomes difficult. Here, in the present embodiment, a so-called inner focus method is adopted. At the time of focusing, focusing from the infinity object point to the near distance object point is performed by moving the second group to the image side. As a result, since the entire lens length can be fixed, operability can be improved. As described above, in the present embodiment, downsizing and weight reduction of the focusing group can be achieved, and a telephoto lens having good aberration correction can be realized.

  Conditional expression (17) relates to the ratio of the maximum ray height of the on-axis light beam on the entrance surface of the first group to the maximum ray height of the on-axis light flux on the entrance surface of the second group. The maximum ray height incident on the first group is determined by the specifications of the telephoto lens. On the other hand, the maximum ray height incident on the second group can be designed appropriately.

  When the value exceeds the upper limit of the conditional expression (17), the diameter of the second group is increased, which makes it difficult to reduce the weight. If the height of the light beam is reduced to a value below the lower limit of the conditional expression (17), although it is advantageous for weight reduction, aberration correction in the first group becomes difficult. Alternatively, it is not preferable because the number of lenses and the total length increase.

  In other words, the lens diameter in the second group does not become too large by falling below the upper limit of the conditional expression (17). Therefore, the weight of the optical system can be reduced. By exceeding the lower limit of the conditional expression (17), aberration correction in the first group is facilitated. Further, it is possible to prevent an increase in the number of lenses and an increase in the overall length of the optical system. As described above, by satisfying the conditional expression (17), it is possible to realize a telephoto lens that is lightweight and achieves good aberration correction.

  Preferably, the stop is disposed closest to the image side of the first group. Thus, the diaphragm is always fixed and can be disposed near the center of the whole. As a result, aberration correction becomes easy for off-axis rays.

  In this embodiment, the first lens unit includes, in order from the object side, a lens unit 1a consisting of one or two positive lenses, a lens unit 1b consisting of a negative-positive cemented lens and a positive-negative cemented lens, and a single lens or It is desirable to be constituted by the 1c group consisting of a cemented lens.

  The group 1a has a function of converging the incident light beam to reduce the lens diameter of the group 1a and thereafter. The group 1b has a role of correcting spherical aberration and chromatic aberration at d-line. It is desirable that the lenses constituting each cemented lens in the first lens group 1b have a large difference in refractive index and a large difference in Abbe number. In addition, it is preferable to use a glass material having large anomalous dispersion as the positive lens that constitutes each cemented lens in the 1 b group. The first lens group 1c has a light convergence function and coma aberration correction at the d-line. When the first lens group 1c is formed of a cemented lens, it is preferable to increase the difference in refractive index between the two lenses.

In the present embodiment, it is desirable to satisfy the following conditional expression (18).
0.55 < _Y1b / _Y1a <0.85 (18)
here,
Y _1a is the maximum ray height of the on-axis ray at the entrance face of the first group,
Y 1 _b is the maximum ray height of the on-axis ray at the entrance face of the 1 b group,
It is.

  The conditional expression (18) relates to the ratio of the maximum ray height of the on-axis light beam in the entrance surface of the group 1a (= the first group) to the maximum ray height of the on-axis light beam in the entrance surface of the 1b group. By satisfying the conditional expression (18), the diameter of the first group b can be reduced. The cemented lens included in the first lens group 1b requires high processing accuracy for all the lenses. In the present embodiment, the processing difficulty of the cemented lens can be lowered by reducing the lens diameter so as to satisfy the conditional expression (18).

If the diameter of the first lens unit 1b is increased beyond the upper limit of the conditional expression (18), it becomes difficult to process the lens.
If the diameter is smaller than the lower limit of the conditional expression (18), enlargement of the total lens length is caused or aberration correction becomes difficult.

  In other words, when the value exceeds the upper limit of the conditional expression (18), the lens diameter of the first lens unit 1b does not become too large. Therefore, processing of the lens becomes easy. By exceeding the lower limit of the conditional expression (18), the lens diameter of the first lens unit 1b does not become too small. Therefore, an increase in the overall length of the optical system can be prevented. Alternatively, aberration correction becomes easy.

  In the present embodiment, the second group desirably comprises a cemented lens. Thereby, the chromatic aberration at the near object point can be corrected well.

  In the present embodiment, the third group is composed of the 3a group of positive refracting power, the 3b group of negative refracting power, and the 3c group of positive refracting power, and the 3b group is a direction perpendicular to the optical axis It is desirable to move the camera to

  Thus, by arranging power in the third group, it is possible to increase the sensitivity at the time of camera shake correction. This makes it possible to reduce the amount of movement of the third group b. As a result, the aberration at the time of camera shake correction can be corrected well. The sensitivity at the time of camera shake correction means the amount of fluctuation of the image relative to the amount of movement of the lens unit.

  In the present embodiment, it is desirable that the third lens group 3a be configured of a single lens or a cemented lens. Here, it is possible to correct the chromatic aberration better when the unit 3a is composed of a cemented lens than when it is composed of a single lens.

  In the present embodiment, it is desirable that the third lens group 3b be configured of a positive and negative cemented lens and a negative lens. Thereby, the chromatic aberration and the curvature of field at the time of camera shake correction can be corrected well.

In the present embodiment, it is desirable that the third c group be configured of a positive and negative cemented lens and a positive and negative cemented lens.
By disposing two cemented lenses in the 3c group, lateral chromatic aberration can be corrected well. In particular, good effects can be obtained for improving resolution around the screen and for improving chromatic aberration performance.

In the present embodiment, it is desirable that the following conditional expression (19) be satisfied.
75 <d d _{1 bp} <100 (19)
here,
d d _{1 bp} is the minimum Abbe number of the positive lens included in the ₁ b group,
It is.

  Conditional expression (19) defines Abbe numbers of the two positive lenses included in the first lens subunit 1b. If the upper limit of conditional expression (19) is exceeded, there will be no glass material that can be used for the lens. Below the lower limit of the conditional expression (19), a glass material having large anomalous dispersion does not exist. That is, by exceeding the lower limit of the conditional expression (19), the positive lens can be made of a glass material having large anomalous dispersion. As described above, in the present embodiment, chromatic aberration can be favorably corrected by satisfying the conditional expression (19).

In the present embodiment, it is desirable to satisfy the following conditional expression (20).
0.42 <D ₁₂ / D ₁ <0.75 (20)
here,
D ₁₂ is the distance from the incident surface of group 1a to the incident surface of group 1b,
D ₁ is the distance from the incident surface of the 1a group to the exit surface of the 1c group,
It is.

Conditional expression (20) relates to the distance between the group 1a and the group 1b. This distance is a distance on the optical axis and is a distance when not converted into air. When the upper limit of conditional expression (20) is exceeded, the height of the on-axis ray decreases. For this reason, it becomes difficult to correct spherical aberration in and after the first lens subunit 1b. Alternatively, the overall length of the lens is undesirably increased.
When the value goes below the lower limit of the conditional expression (20), aberration correction is advantageous, but processing of the first lens group 1b becomes difficult.

  In other words, the height of the on-axis ray does not become too low by falling below the upper limit of the conditional expression (20). This facilitates correction of spherical aberration in the rear lens unit. The rear lens group is a lens group located on the image side of the first lens group 1b. Alternatively, an increase in the overall length of the optical system can be suppressed. By exceeding the lower limit of the conditional expression (20), processing of the lens constituting the first lens group b becomes easy. As described above, according to the present embodiment, by satisfying the conditional expression (20), ease of processing and favorable aberration correction can be realized simultaneously.

  On the other hand, as a trend in recent years, needs for not only still pictures but also moving picture shooting are increasing. For this reason, also in a lens interchangeable type digital camera, an interchangeable lens optimized for a moving image shooting function is required. Generally, in moving image shooting, it is necessary to keep the autofocus (AF) at all times in order to maintain the in-focus state. As the method, so-called wobbling is performed by always moving the focus lens by a small amount before and after the in-focus position. At this time, a change in contrast of the captured image is measured, and when it is determined that the in-focus state has changed, the focus lens is appropriately moved. Then, it is operated to refocus again. With such a wobbling mechanism, even if the distance to the subject changes, the in-focus state can always be maintained.

  Wobbling requires very fast operation, depending on the frame rate of the body. For this reason, in wobbling, in order to perform appropriate drive control, weight reduction of the focus lens and a small amount of movement are required.

Furthermore, in moving image shooting, audio is often recorded simultaneously. For this reason, if a sound is generated with wobbling during moving image shooting, this sound is recorded as a sound. Thus, noise reduction during wobbling is also an important issue.
Usually, the focus lens and the wobbling lens are often the same lens. However, the present invention is not limited to this, and the focus lens and the wobbling lens may be configured as separate lens groups.

  As described above, a lens compatible with moving image shooting has many problems to be solved. In particular, weight reduction is required for the focus lens group. The present embodiment can also solve such a problem, and by using the lens configuration as described above, the miniaturization and weight reduction of the focus group are realized.

  Further, the imaging device according to the present embodiment includes the telephoto lens according to any one of the above embodiments, and an imaging element having an imaging surface and converting an image formed on the imaging surface by the telephoto lens into an electric signal. It is characterized by having.

  Moreover, as for the above-mentioned structure, it is more preferable to mutually satisfy two or more simultaneously. Also, some configurations may be satisfied at the same time.

  As for the conditional expressions, each conditional expression may be individually satisfied. This is preferable because it becomes easy to obtain each effect.

  In each conditional expression, the lower limit value or the upper limit value may be changed as follows. This is preferable because the effects of each conditional expression can be further ensured.

In conditional expression (1), it is preferable to set the lower limit value to 0.417, 0.434, 0.451, and the upper limit value to 0.773, 0.746, and 0.719.
In conditional expression (2), it is preferable to set the lower limit value to 0.422, 0.444, 0.467, and the upper limit value to 0.981, 0.963, 0.944.
For conditional expression (3), it is preferable to set the lower limit value to 4.154, 4.307, 4.461 and the upper limit value to 13.865, 12.730, or 11.59.
For conditional expression (4), it is preferable to set the lower limit value to 18.365, 20.730, 23.095, and the upper limit value to 54.493, 53.985, 53.478.
In conditional expression (5), it is preferable to set the lower limit value to 0.356, 0.363, 0.369, and the upper limit value to 0.992, 0.984, 0.977.
For conditional expression (6), it is preferable to set the lower limit value to 0.426, 0.432, 0.439, and the upper limit value to 0.519, 0.518.
In conditional expression (7), it is preferable to set the lower limit value to 1.005, 1.010, 1.015, and the upper limit value to 1.160, 1.120, 1.080.
In conditional expression (8), it is preferable to set the lower limit value to 0.601, 0.602, and the upper limit value to 0.672, 0.665, 0.657.
In conditional expression (9), it is preferable to set the lower limit value to 0.063, 0.075, 0.088 and the upper limit value to 0.143, 0.135, 0.128.
In conditional expression (10), it is preferable to set the lower limit value to 0.683, 0.716, and 0.750, and the upper limit value to 0.932, 0.914, and 0.896.
For conditional expression (11), it is preferable to set the lower limit value to 0.409, 0.418, 0.427, and the upper limit value to 0.491, 0.482, 0.473.
For conditional expression (12), it is preferable to set the lower limit value to -0.231, -0.213, -0.194 and the upper limit value to -0.114, -0.128, -0.141.
In conditional expression (13), it is preferable to set the lower limit value to 0.117, 0.134, 0.151, and the upper limit value to 0.281, 0.261, 0.242.
For conditional expression (14), it is preferable to set the lower limit value to -0.091, -0.083, -0.074 and the upper limit value to -0.038, -0.045, -0.053.
For conditional expression (15), it is preferable to set the lower limit value to 87.483, 89.965, 92.448 and the upper limit value to 98.775, 98.000, 96.000.
For conditional expression (16), it is preferable to set the lower limit value to 72.885, 75.770, 78.655, and the upper limit value to 98.775, 98.000, 96.000.
In conditional expression (17), it is preferable to set the lower limit value to 0.25 and the upper limit value to 0.3 or 0.28.
In conditional expression (18), it is preferable to set the lower limit value to 0.58, 0.60, and the upper limit value to 0.8 or 0.79.
In conditional expression (19), it is preferable to set the lower limit value to 76, 78 and the upper limit value to 98, 96.
In conditional expression (20), it is preferable to set the lower limit value to 0.43, 0.46 and the upper limit value to 0.73, 0.70.

  Examples 1 to 6 of the telephoto lens will be described below. Lens cross sections at the time of infinite object point focusing in the first to sixth embodiments are respectively shown in FIGS. 1 to 3. The first to sixth embodiments are composed of, in order from the object side, a first lens group G1 of positive refractive power, a second lens group G2 of negative refractive power, and a rear lens group GR of positive refractive power. The rear lens group GR comprises a third lens group G3 of positive refracting power, a fourth lens group G4 of negative and positive refracting power, and a fifth lens group G5 of positive refracting power. The second lens group G2 moves toward the image side to perform focusing from an infinite object point to a near object point.

  The aperture stop (brightness stop) is denoted by S, and the image plane (imaging surface) is denoted by I. The movement of the lens group moving at the time of focusing is indicated by an arrow parallel to the optical axis AX, and the movement of the lens group moving at the time of camera shake correction is indicated by an arrow perpendicular to the optical axis AX.

  Note that, between the lens group located closest to the image side and the image plane I, a parallel flat plate that constitutes a low pass filter, or a cover glass of the electronic imaging device may be disposed. In this case, the surface of the parallel flat plate may be provided with a wavelength range limiting coat for limiting infrared light. In addition, a multilayer film for wavelength range limitation may be provided on the surface of the cover glass. In addition, the cover glass may have a low pass filter action.

  The telephoto lens of Example 1 will be described. FIG. 1A shows the cross-sectional configuration of the telephoto lens of Example 1. FIG.

  The first lens group G1 has a positive meniscus lens L1 having a convex surface on the object side, a negative meniscus lens L2 having a convex surface on the object side, a positive meniscus lens L3 having a convex surface on the object side, and a biconvex positive lens It comprises L4, a biconcave negative lens L5, a negative meniscus lens L6 having a convex surface facing the object side, a biconvex positive lens L7, and a stop S. Here, the negative meniscus lens L2 and the positive meniscus lens L3 are cemented. The positive lens L4 and the negative lens L5 are cemented. The negative meniscus lens L6 and the positive lens L7 are cemented.

  The first sub lens unit SU1 is composed of a positive meniscus lens L1. The second sub lens unit SU2 is composed of a negative meniscus lens L2, a positive meniscus lens L3, a positive lens L4, and a negative lens L5. The third sub lens unit SU3 is composed of a negative meniscus lens L6 and a positive lens L7.

  The second lens group G2 is composed of a biconvex positive lens L8 and a biconcave negative lens L9. Here, the positive lens L8 and the negative lens L9 are cemented. The second lens group G2 monotonously moves to the image side at the time of focusing on the near object point.

  The third lens group G3 is composed of a positive meniscus lens L10 having a convex surface facing the object side.

  The fourth lens group G4 is composed of a biconvex positive lens L11, a biconcave negative lens L12, and a biconcave negative lens L13. Here, the positive lens L11 and the negative lens L12 are cemented.

  The fifth lens group G5 is composed of a biconvex positive lens L14, a negative meniscus lens L15 having a convex surface facing the image side, a biconvex positive lens L16, and a negative meniscus lens L17 having a convex surface facing the image side. . Here, the positive lens L14 and the negative meniscus lens L15 are cemented. The positive lens L16 and the negative meniscus lens L17 are cemented.

  Also, at the time of camera shake correction, the fourth lens group G4 moves in the direction orthogonal to the optical axis AX.

  The telephoto lens of Example 2 will be described. FIG. 1B shows the cross-sectional configuration of the telephoto lens of Example 2. FIG.

  The first lens group G1 has a positive meniscus lens L1 having a convex surface on the object side, a positive meniscus lens L2 having a convex surface on the object side, a negative meniscus lens L3 having a convex surface on the object side, and a convex surface on the object side A positive meniscus lens L4 with a convex surface facing the object side, a biconvex positive lens L5, a biconcave negative lens L6, a positive meniscus lens L7 with a convex surface facing the object side, and a stop S. Here, the negative meniscus lens L3 and the positive meniscus lens L4 are cemented. The positive lens L5 and the negative lens L6 are cemented.

  The first sub lens unit SU1 is composed of a positive meniscus lens L1 and a positive meniscus lens L2. The second sub lens unit SU2 includes a negative meniscus lens L3, a positive lens L4, a positive lens L5, and a negative lens L6. The third sub lens unit SU3 is composed of a positive meniscus lens L7.

  The second lens group G2 is composed of a biconvex positive lens L8 and a biconcave negative lens L9. Here, the positive lens L8 and the negative lens L9 are cemented. The second lens group G2 monotonously moves to the image side at the time of focusing on the near object point.

  The third lens group G3 is composed of a biconvex positive lens L10 and a negative meniscus lens L11 having a convex surface directed to the image side. Here, the positive lens L10 and the negative meniscus lens L11 are cemented.

  The fourth lens group G4 is composed of a positive meniscus lens L12 convex on its image side, a biconcave negative lens L13, and a biconcave negative lens L14. Here, the positive meniscus lens L12 and the negative lens L13 are cemented.

  The fifth lens group G5 is composed of a biconvex positive lens L15, a negative meniscus lens L16 with a convex surface facing the image side, a biconvex positive lens L17, and a negative meniscus lens L18 with a convex surface facing the image side . Here, the positive lens L15 and the negative meniscus lens L16 are cemented. The positive lens L17 and the negative meniscus lens L18 are cemented.

  Also, at the time of camera shake correction, the fourth lens group G4 moves in the direction orthogonal to the optical axis AX.

  The telephoto lens of Example 3 will be described. FIG. 2A shows the cross-sectional configuration of the telephoto lens of Example 3. FIG.

  The first lens group G1 has a positive meniscus lens L1 having a convex surface on the object side, a negative meniscus lens L2 having a convex surface on the object side, a positive meniscus lens L3 having a convex surface on the object side, and a biconvex positive lens It comprises L4, a biconcave negative lens L5, a negative meniscus lens L6 having a convex surface facing the object side, a biconvex positive lens L7, and a stop S. Here, the negative meniscus lens L2 and the positive meniscus lens L3 are cemented. The positive lens L4 and the negative lens L5 are cemented. The negative meniscus lens L6 and the positive lens L7 are cemented.

  The first sub lens unit SU1 is composed of a positive meniscus lens L1. The second sub lens unit SU2 is composed of a negative meniscus lens L2, a positive meniscus lens L3, a positive lens L4, and a negative lens L5. The third sub lens unit SU3 is composed of a negative meniscus lens L6 and a positive lens L7.

  The second lens group G2 is composed of a biconvex positive lens L8 and a biconcave negative lens L9. Here, the positive lens L8 and the negative lens L9 are cemented. The second lens group G2 monotonously moves to the image side at the time of focusing on the near object point.

  The third lens group G3 is composed of a biconvex positive lens L10.

  The fourth lens group G4 is composed of a biconvex positive lens L11, a biconcave negative lens L12, and a biconcave negative lens L13. Here, the positive lens L11 and the negative lens L12 are cemented.

  The fifth lens group G5 is composed of a biconvex positive lens L14, a negative meniscus lens L15 having a convex surface facing the image side, a biconvex positive lens L16, and a negative meniscus lens L17 having a convex surface facing the image side. . Here, the positive lens L14 and the negative meniscus lens L15 are cemented. The positive lens L16 and the negative meniscus lens L17 are cemented.

  Also, at the time of camera shake correction, the fourth lens group G4 moves in the direction orthogonal to the optical axis AX.

  The telephoto lens of Example 4 will be described. FIG. 2B shows the cross-sectional configuration of the telephoto lens of Example 4.

The first lens group G1 has a positive meniscus lens L1 having a convex surface on the object side, a negative meniscus lens L2 having a convex surface on the object side, a positive meniscus lens L3 having a convex surface on the object side, and a biconvex positive lens It comprises L4, a biconcave negative lens L5, a negative meniscus lens L6 having a convex surface facing the object side, a biconvex positive lens L7, and a stop S. Here, the negative meniscus lens L2 and the positive meniscus lens L3 are cemented. The positive lens L4 and the negative lens L5 are cemented. The negative meniscus lens L6 and the positive lens L7 are cemented.

  The first sub lens unit SU1 is composed of a positive meniscus lens L1. The second sub lens unit SU2 is composed of a negative meniscus lens L2, a positive meniscus lens L3, a positive lens L4, and a negative lens L5. The third sub lens unit SU3 is composed of a negative meniscus lens L6 and a positive lens L7.

  The second lens group G2 is composed of a biconvex positive lens L8 and a biconcave negative lens L9. Here, the positive lens L8 and the negative lens L9 are cemented. The second lens group G2 monotonously moves to the image side at the time of focusing on the near object point.

  The third lens group G3 is composed of a biconvex positive lens L10.

  The fourth lens group G4 is composed of a biconvex positive lens L11, a biconcave negative lens L12, and a biconcave negative lens L13. Here, the positive lens L11 and the negative lens L12 are cemented.

  The fifth lens group G5 is composed of a biconvex positive lens L14, a negative meniscus lens L15 having a convex surface facing the image side, a biconvex positive lens L16, and a negative meniscus lens L17 having a convex surface facing the image side. . Here, the positive lens L14 and the negative meniscus lens L15 are cemented. The positive lens L16 and the negative meniscus lens L17 are cemented.

  Also, at the time of camera shake correction, the fourth lens group G4 moves in the direction orthogonal to the optical axis AX.

  The telephoto lens of Example 5 will be described. FIG. 3A shows the cross-sectional configuration of the telephoto lens of Example 5. FIG.

  The first lens group G1 has a positive meniscus lens L1 having a convex surface on the object side, a positive meniscus lens L2 having a convex surface on the object side, a negative meniscus lens L3 having a convex surface on the object side, and a convex surface on the object side A positive meniscus lens L4 having a convex surface facing the object side, a biconvex positive lens L5, a biconcave negative lens L6, a positive meniscus lens L7 having a convex surface facing the object side, and a stop. Here, the negative meniscus lens L3 and the positive meniscus lens L4 are cemented. The positive lens L5 and the negative lens L6 are cemented.

  The first sub lens unit SU1 is composed of a positive meniscus lens L1 and a positive meniscus lens L2. The second sub lens unit SU2 includes a negative meniscus lens L3, a positive meniscus lens L4, a positive lens L5, and a negative lens L6. The third sub lens unit SU3 is composed of a positive meniscus lens L7.

  The second lens group G2 is composed of a biconvex positive lens L8 and a biconcave negative lens L9. Here, the positive lens L8 and the negative lens L9 are cemented. The second lens group G2 monotonously moves to the image side at the time of focusing on the near object point.

  The third lens group G3 is composed of a negative meniscus lens L10 with a convex surface facing the object side, and a biconvex positive lens L11. Here, the negative meniscus lens L10 and the positive lens L11 are cemented.

  The fourth lens group G4 is composed of a positive meniscus lens L12 convex on its image side, a biconcave negative lens L13, and a biconcave negative lens L14. Here, the positive meniscus lens L12 and the negative lens L13 are cemented.

  The fifth lens group G5 is composed of a biconvex positive lens L15, a negative meniscus lens L16 with a convex surface facing the image side, a biconvex positive lens L17, and a negative meniscus lens L18 with a convex surface facing the image side . Here, the positive lens L15 and the negative meniscus lens L16 are cemented. The positive lens L17 and the negative meniscus lens L18 are cemented.

  Also, at the time of camera shake correction, the fourth lens group G4 moves in the direction orthogonal to the optical axis AX.

  The telephoto lens of Example 6 will be described. FIG. 3B shows the cross-sectional configuration of the telephoto lens of Example 6.

  The first lens group G1 has a positive meniscus lens L1 having a convex surface on the object side, a positive meniscus lens L2 having a convex surface on the object side, a negative meniscus lens L3 having a convex surface on the object side, and a convex surface on the object side Is composed of a positive meniscus lens L4 facing the lens, a biconvex positive lens L5, a biconcave negative lens L6, a negative meniscus lens L7 with the convex surface facing the object side, a biconvex positive lens L8, and a stop S. . Here, the negative meniscus lens L3 and the positive meniscus lens L4 are cemented. The positive lens L5 and the negative lens L6 are cemented. The negative meniscus lens L7 and the positive lens L8 are cemented.

  The first sub lens unit SU1 is composed of a positive meniscus lens L1 and a positive meniscus lens L2. The second sub lens unit SU2 includes a negative meniscus lens L3, a positive meniscus lens L4, a positive lens L5, and a negative lens L6. The third sub lens unit SU3 includes a negative meniscus lens L7 and a positive lens L8.

  The second lens group G2 is composed of a biconvex positive lens L9 and a biconcave negative lens L10. Here, the positive lens L9 and the negative lens L10 are cemented. The second lens group G2 monotonously moves to the image side at the time of focusing on the near object point.

  The third lens group G3 is composed of a negative meniscus lens L11 with a convex surface facing the object side and a biconvex positive lens L12. Here, the negative meniscus lens L11 and the positive lens L12 are cemented.

  The fourth lens group G4 is composed of a biconvex positive lens L13, a biconcave negative lens L14, and a biconcave negative lens L15. Here, the positive lens L13 and the negative lens L14 are cemented.

  The fifth lens group G5 is composed of a biconvex positive lens L16, a negative meniscus lens L17 having a convex surface facing the image side, a biconvex positive lens L18, and a negative meniscus lens L19 having a convex surface facing the image side. . Here, the positive lens L16 and the negative meniscus lens L17 are cemented. The positive lens L18 and the negative meniscus lens L19 are cemented.

  Also, at the time of camera shake correction, the fourth lens group G4 moves in the direction orthogonal to the optical axis AX.

  Below, numerical data of each of the above examples are shown. Symbols are outside the above, r is a radius of curvature of each lens surface, d is a distance between each lens surface, nd is a refractive index of d line of each lens, and d d is Abbe's number of each lens. Also, f is the focal length of the whole system, Fno. Is the f-number, ω is the half angle of view, IH is the image height, BF is the back focus, and the total length is the distance from the most object side lens surface of the telephoto lens to the most image side lens surface is there. Here, BF is expressed by converting the distance from the lens final surface to the paraxial image surface into air.

Numerical embodiment 1
Unit mm

Plane data Plane number rd nd dd
1 82.391 10.50 1.48749 70.23
2 280.921 45.60
3 82.520 2.96 1.74100 52.64
4 47.128 9.79 1.43700 95.10
5 346.425 1.30
6 74.653 9.45 1.43700 95.10
7 -119.184 2.38 1.80610 40.92
8 164.514 28.52
9 77.016 1.90 1.77250 49.60
10 41.957 7.34 1.54814 45.79
11-263.942 3.95
12 (stop) ∞ variable
13 164.735 1.88 1.80810 22.76
14 -172.861 0.97 1.71300 53.87
15 26.686 Variable
16 30.684 3.61 1.49700 81.61
17 529.265 3.30
18 182.862 3.25 1.80810 22.76
19 -38.287 0.90 1.60311 60.64
20 20. 648 5.08
21 -26.287 0.90 1.71300 53.87
22 124.505 2.28
23 60.842 8.12 1.58313 59.38
24-24.754 1.80 1.92286 20.88
25-40.288 0.29
26 112.212 9.46 1.72047 34.71
27 -22.904 1.80 1.92286 20.88
28 -44.272 31.75
29 4.00 1.51633 64.14
30 0.8 0.80
Image plane

Group distance infinite object point 1.4 m
d12 20.300 37.495
d15 24.210 7.015

Various data (infinity object point)
Focal distance f 293.94
Fno 4.08
Angle of view (2ω) 4.23 °
Image height IH 10.82
BF (in AIR) 35.19
Total length (in AIR) 247.03

Numerical embodiment 2
Unit mm

Plane data Plane number rd nd dd
1 152.697 7.35 1.48749 70.23
2 635.660 17.00
3 65.873 9.98 1.49700 81.61
4 168.604 22.65
5 83.128 3.00 1.83400 37.16
6 39.401 9.99 1.49700 81.61
7 247.375 0.20
8 47.092 9.09 1.43700 95.10
9-375.772 2.50 1.77250 49.60
10 52.273 16.34
11 103.357 4.29 1.80518 25.46
12 1037.201 4.13
13 (stop) ∞ variable
14 515.932 2.54 1.85478 24.80
15-52. 053 0.90 1.7 1300 53. 87
16 28.700 Variable
17 30.889 6.80 1.49700 81.61
18 -37.936 1.50 1.85478 24.80
19 -60.988 3.10
20 -230.987 3.79 1.85478 24.80
21-27.890 1.00 1.69680 55.53
22 34.148 3.37
23 -44.563 1.00 1.58313 59.38
24 32.470 3.42
25 43.045 9.01 1.64769 33.79
26-22.000 1.60 1.92286 20.88
27 -88.862 1.50
28 72.000 8.75 1.59270 35.31
29 -26.858 1.70 1.92286 20.88
30-40.716 29.05
31 ∞ 4.00 1.51633 64.14
32 0.8 0.80
Image plane

Group distance infinite object point 1.4 m
d13 20.000 37.439
d16 19.840 2.401

Various data (infinity object point)
Focal length f 294.10
Fno 4.080
Angle of view (2ω) 4.23 °
Image height IH 10.82
BF (in AIR) 32.49
Total length (in AIR)

Numerical embodiment 3
Unit mm

Plane data Plane number rd nd dd
1 83.614 10.60 1.48749 70.23
2 354.620 44.96
3 121.115 3.20 1.73400 51.47
4 51.291 9.20 1.43875 94.93
5 492.362 1.00
6 63.414 10.48 1.43875 94.93
7-127.021 3.06 1.80610 40.92
8 204.246 23.99
9 73.423 2.67 1.73400 51.47
10 38.139 7.38 1.54814 45.79
11-653.693 4.07
12 (stop) ∞ variable
13 684.319 2.10 1.80810 22.76
14 -99.610 0.80 1.7130 53.87
15 30.683 Variable
16 35.344 5.38 1.43875 94.93
17-90.808 3.94
18 181.821 2.45 1.92286 18.90
19 -68.416 0.90 1.61800 63.40
20 21.925 4.19
21-34.422 0.90 1.71300 53.87
22 54.789 3.11
23 57.947 7.94 1.74951 35.33
24-24.316 1.80 1.92286 20.88
25 -82.795 0.20
26 60.000 8.58 1.6541 2 39.68
27-26.918 2.30 1.92286 20.88
28-50.468 30.12
29 4.00 1.51633 64.14
30 0.8 0.80
Image plane

Group distance infinite object point 1.4 m
d12 20.350 37.180
d15 24.090 7.260

Various data (infinity object point)
Focal length f 291.04
Fno 4.08
Angle of view (2ω) 4.27 °
Image height IH 10.82
BF (in AIR) 33.56
Total length (in AIR) 243.20

Numerical embodiment 4
Unit mm

Plane data Plane number rd nd dd
1 84.042 10.54 1.48749 70.23
2 355.169 45.98
3 117.315 3.20 1.73400 51.47
4 50.625 9.17 1.43875 94.93
5 436.317 1.00
6 62.921 10.37 1.43875 94.93
7-126.963 3.06 1.80610 40.92
8 220.101 23.97
9 77.092 2.61 1.73400 51.47
10 39.084 7.18 1.54814 45.79
11-608.540 3.53
12 (stop) ∞ variable
13 785.048 2.10 1.80810 22.76
14 -97.884 0.80 1.71300 53.87
15 30.770 variable
16 35.022 5.52 1.43875 94.93
17 -88.540 3.94
18 272.276 2.45 1.92286 20.88
19-57.482 0.90 1.61800 63.40
20 22.993 3.96
21 -35.578 0.90 1.69680 55.53
22 47.710 3.28
23 55.325 8.11 1.74951 35.33
24-23.482 1.80 1.92286 20.88
25-79.458 0.30
26 55.293 8.49 1.59551 39.24
27 -27.707 2.30 1.92286 20.88
28 -47.799 29.45
29 4.00 1.51633 64.14
30 0.8 0.80
Image plane

Group distance infinite object point 1.4 m
d12 20.300 37.137
d15 23.990 7.153

Various data (infinity object point)
Focal distance f 291.00
Fno 4.08
Angle of view (2ω) 4.27 °
Image height IH 10.82
BF (in AIR) 32.89
Total length (in AIR) 242.64

Numerical embodiment 5
Unit mm

Plane data Plane number rd nd dd
1 100.000 6.30 1.48749 70.23
2 185.738 30.22
3 65.495 8.86 1.49700 81.61
4 182.775 31.49
5 102.065 3.00 1.83400 37.16
6 35.358 9.46 1.49700 81.61
7 353.069 3.03
8 50.366 8.26 1.43700 95.10
9-127.828 2.60 1.77250 49.60
10 68.292 3.78
11 60.689 4.19 1.80518 25.46
12 184.940 3.74
13 (stop) ∞ variable
14 3189.272 1.86 1.84666 23.78
15 -102.991 1.00 1.77250 49.60
16 33.769 Variable
17 36.244 1.50 1.84666 23.78
18 25.239 5.84 1.49700 81.61
19 -65.798 3.29
20 -231.178 3.35 1.80518 25.46
21 -26.952 1.00 1.69680 55.53
22 25.434 3.38
23 -44.292 1.00 1.58313 59.38
24 58.276 3.30
25 47.386 6.21 1.64769 33.79
26 -44.237 1.50 1.92286 18.90
27 -72.107 1.11
28 55.076 9.00 1.69895 30.13
29 -30.980 1.50 1.92286 18.90
30 -100.926 29.84
31 ∞ 4.00 1.51633 64.14
32 0.8 0.80
Image plane

Group distance infinite object point 1.4 m
d13 21.850 39.351
d16 22.000 4.499

Various data (infinity object point)
Focal distance f 294.00
Fno 4.08
Angle of view (2ω) 4.21 °
Image height IH 10.82
BF (in AIR) 33.28
Total length (in AIR) 236.90

Numerical embodiment 6
Unit mm

Plane data Plane number rd nd dd
100.000 8.00 1.48749 70.23
2 190.479 30.50
3 275.922 4.66 1.49700 81.54
4 1341.851 26.00
5 96.636 3.20 1.88341 42.71
6 58.200 9.57 1.49700 81.54
7 2218.640 0.20
8 76.585 5.39 1.43875 94.93
9 -156.187 2.60 1.75500 52.32
10 163.211 30.47
11 204.208 3.00 1.69100 54.82
12 53.155 6.00 1.57135 52.97
13 -239.111 2.68
14 (stop) ∞ variable
15 632.607 2.03 1.85478 24.80
16-95.464 0.90 1.75500 52.32
17 34.618 Variable
18 29.238 1.85 1.85478 24.80
19 22.213 6.00 1.48749 70.23
20 -96.295 3.10
21 100.398 3.18 1.85478 24.80
22 -45.430 0.90 1.72916 54.68
23 24.049 3.79
24-34.481 0.90 1.69680 55.53
25 46.160 3.30
26 57.204 6.85 1.60300 65.44
27-28.719 1.60 1.83400 37.16
28 -56.678 0.64
29 48.060 10.00 1.61340 44.27
30-24.953 1.50 1.69895 30.13
31-83. 250 26. 79
32 ∞ 4.00 1.51633 64.14
33 0.8 0.80
Image plane

Group distance infinite object point 1.4 m
d14 21.850 41.737
d17 22.000 2.113

Various data (infinity object point)
Focal length 294.00
Fno 4.08
Angle of view (2ω) 4.22 °
Image height 10.82
BF (in AIR) 30.23
Total length (in AIR) 256.89

The aberration diagrams of the above Examples 1 to 6 are shown in FIGS. 4 to 6, respectively. An aberration diagram at the time of infinite object point focusing is shown to one example. In each figure, "FIY" indicates the maximum image height.
In these aberration diagrams, spherical aberration (SA), astigmatism (AS), distortion (DT) and lateral chromatic aberration (CC) are shown, respectively.

Next, the values of conditional expressions in each example will be raised.
Conditional Expression Example 1 Example 2 Example 3 Example 4 Example 5 Example 6
(1) d _su 1 _{o 2} / d _{G 1} 0.469 0.556 0.477 0.483 0.691 0.518
(2) f _su1 / f 0.800 0.489 0.762 0.766 0.494 0.925
(3) f _su1 / d _su1i2 5.155 6.344 4.929 4.850 4.614 10.461
(4) _{su su3pmin} 45.79 25.46 45.79 45.79 25.46 52.97
(5) f _su3 / f 0.504 0.484 0.572 0.603 0.376 0.969
(6) d _G1 / L _TL 0.482 0.445 0.477 0.480 0.467 0.517
(7) d _su1s / d _G1 1.033 1.040 1.035 1.030 1.034 1.020
(8) θgF G5 _min 0.639 0.639 0.639 0.639 0.650 0.603
(9) f _G5 / f 0.100 0.120 0.104 0.105 0.104 0.105
(10) L _TL / f 0.845 0.783 0.840 0.838 0.810 0.878
(11) f _G1 / f 0.436 0.442 0.438 0.438 0.438 0.464
(12) f _G2 / f-0.162-0.155-0.163-0.163-0.163-0.156-0.176
(13) f _G3 / f 0.222 0.168 0.202 0.199 0.201 0.191
(14) f _G4 / f-0.062-0.065-0.063-0.063-0.065-0.061
_{(15) ν sub2op 95.10 81.61 94.93} 94.93 81.61 81.54
(16) _sub sub2ip 95. 10 95. 10 94. 93 94. 93 94. 93
(17) Y ₂ / Y _1a 0.266 0.272 0.272 0.271 0.260 0.269
_{(18) Y 1b / Y 1a} 0.755 0.721 0.753 0.749 0.641 0.783
(19) d d _{1 bp} 95.10 81.
_{(20) D 12 / D 1} 0.469 0.556 0.477 0.483 0.691 0.518

  FIG. 7 is a cross-sectional view of a single-lens mirrorless camera as an electronic imaging device. In FIG. 7, a photographing lens system 2 is disposed in a lens barrel of a single-lens mirrorless camera 1. The mount unit 3 enables the taking lens system 2 to be detachably attached to the body of the single-lens mirrorless camera 1. As the mount portion 3, a screw type mount, a bayonet type mount, or the like is used. In this example, a bayonet type mount is used. Further, in the body of the single-lens mirrorless camera 1, an imaging element surface 4 and a back monitor 5 are disposed. As the imaging device, a compact CCD or CMOS is used.

  Then, for example, the telephoto lenses shown in the first to sixth embodiments are used as the taking lens system 2 of the single-lens mirrorless camera 1.

  FIG. 8 and FIG. 9 show conceptual diagrams of the configuration of the imaging device having the telephoto lens shown in the first to sixth embodiments. FIG. 8 is a front perspective view showing the appearance of a digital camera 40 as an imaging device, and FIG. 9 is a rear perspective view of the same. The telephoto lens of this embodiment is used for the photographing optical system 41 of the digital camera 40.

  The digital camera 40 of this embodiment includes a photographing optical system 41 located on the photographing optical path 42, a shutter button 45, a liquid crystal display monitor 47 and the like, and pressing the shutter button 45 disposed above the digital camera 40 In conjunction with that, photographing is performed through the photographing optical system 41, for example, the telephoto lens of the first embodiment. An object image formed by the photographing optical system 41 is formed on an image pickup element (photoelectric conversion surface) provided in the vicinity of the imaging surface. The object image received by the imaging device is displayed as an electronic image on the liquid crystal display monitor 47 provided on the back of the camera by the processing means. Also, the captured electronic image can be recorded in the recording means.

  FIG. 10 is a block diagram showing an internal circuit of a main part of the digital camera 40. As shown in FIG. In the following description, the above-mentioned processing means is composed of, for example, the CDS / ADC unit 24, the temporary storage memory 17, the image processing unit 18 and the like, and the storage means is composed of the storage medium unit 19 etc.

  As shown in FIG. 10, the digital camera 40 is connected to the operation unit 12, the control unit 13 connected to the operation unit 12, and the control signal output port of the control unit 13 via the buses 14 and 15. The imaging drive circuit 16, the temporary storage memory 17, the image processing unit 18, the storage medium unit 19, the display unit 20, and the setting information storage memory unit 21 are provided.

The temporary storage memory 17, the image processing unit 18, the storage medium unit 19, the display unit 20, and the setting information storage memory unit 21 can mutually input and output data via the bus 22. Further, a CCD 49 and a CDS / ADC unit 24 are connected to the imaging drive circuit 16.

  The operation unit 12 includes various input buttons and switches, and notifies the control unit 13 of event information input from the outside (camera user) via these. The control unit 13 is a central processing unit including, for example, a CPU, incorporates a program memory (not shown), and controls the entire digital camera 40 according to a program stored in the program memory.

  The CCD 49 is an imaging element which is drive-controlled by the imaging drive circuit 16, converts the light quantity of each pixel of the object image formed via the imaging optical system 41 into an electrical signal, and outputs the electrical signal to the CDS / ADC unit 24.

  The CDS / ADC unit 24 amplifies the electrical signal input from the CCD 49, performs analog / digital conversion, and performs raw video data (Bayer data, hereinafter referred to as RAW data) that has only been subjected to this amplification and digital conversion. Are output to the temporary storage memory 17.

  The temporary storage memory 17 is a buffer made of, for example, an SDRAM or the like, and is a memory device for temporarily storing RAW data output from the CDS / ADC unit 24. The image processing unit 18 reads out the RAW data stored in the temporary storage memory 17 or the RAW data stored in the storage medium unit 19, and includes distortion correction based on the image quality parameter designated by the control unit 13. It is a circuit that electrically performs various image processing.

  The storage medium unit 19 detachably mounts, for example, a card type or stick type recording medium including a flash memory, and RAW data transferred from the temporary storage memory 17 or the image processing unit 18 to these flash memories. The image data subjected to the image processing is recorded and held.

  The display unit 20 is configured by a liquid crystal display monitor 47 or the like, and displays captured RAW data, image data, an operation menu, and the like. The setting information storage memory unit 21 is provided with a ROM unit in which various image quality parameters are stored in advance, and a RAM unit which stores the image quality parameters read from the ROM unit by the input operation of the operation unit 12.

  The digital camera 40 configured in this way is advantageous for obtaining a high resolution image without deteriorating the image quality while being small and lightweight by adopting the telephoto lens of the present embodiment as the photographing optical system 41. It is possible to make an image pickup apparatus.

  As described above, the present invention is suitable for a telephoto lens in which the reduction of the diameter of the optical system is achieved and the occurrence of various aberrations are well suppressed, and an imaging apparatus having the same.

G1 First lens group G2 Second lens group G3 Fourth lens group G5 Fifth lens group GR Rear lens group S Aperture stop I Image plane 1 Single-lens mirrorless camera 2 Shooting lens system 3 Lens barrel mount 4 Image pickup element surface 5 Back monitor 12 Operation unit 13 Control unit 14, 15 Bus 16 Image pickup drive circuit 17 Temporary storage memory 18 Image processing unit 19 Storage medium unit 20 Display unit 21 Setting information storage memory unit 22 Bus 24 CDS / ADC unit 40 Digital Camera 41 Shooting optical system 42 Optical path for shooting 45 Shutter button 47 Liquid crystal display monitor 49 CCD

Claims (10)

In order from the object side to the image side,
A first lens unit having a fixed position and a positive refractive power,
A second lens unit of negative refractive power that moves to the image side along the optical axis during focusing from an infinite object point to a near object point;
When focusing, the position in the optical axis direction consists of a fixed positive power rear lens group,
The rear lens unit includes a third lens unit having a fixed position and a positive refractive power, a fourth lens unit having a negative refractive power and a camera shake reduction lens moving in a direction perpendicular to the optical axis, and a positive refractive power having a fixed position. And the fifth lens group of
The fifth lens group includes, in order from the object side to the image side, possess the object side cemented lens, and the image side cemented lens, and
Each of the object-side cemented lens and the image-side cemented lens has a positive lens and a negative lens,
A telephoto lens characterized by satisfying the following conditional expression (8) .
0.60 <θgF _G5min <0.68 (8)
here,
θgF _G5min is the minimum θgF of the negative lens θgF in the fifth lens group,
θ _gF is a partial dispersion ratio, and is expressed by θ _gF = (ng−nF) / (nF−nC)
nC, nF, ng are the refractive index to C line, F line, g line, respectively
It is. The telephoto lens according to claim 1, wherein the following conditional expression (9) is satisfied.
0.05 ≦ f _G5 / F ≦ 0.15 (9)
here,
f _G5 Is the focal length of the fifth lens group,
f is the focal length of the entire telephoto lens system when focusing on an infinite object point,
It is. The telephoto lens according to claim 1, wherein the following conditional expression (10) is satisfied.
0.65 <L _TL / F <0.95 (10)
here,
L _TL Is the distance from the object side surface of the lens located closest to the object side of the telephoto lens to the image plane when focusing on an infinite object point
f is the focal length of the entire telephoto lens system when focusing on an infinite object point,
It is. The object side cemented lens of the fifth lens group consists of, in order from the object side to the image side, a positive single lens and a negative single lens, and the image side cemented lens of the fifth lens group is arranged from the object side The telephoto lens according to any one of claims 1 to 3, characterized in that on the image side, a positive single lens and a negative single lens are provided in order. The telephoto according to any one of claims 1 to 4, wherein the first lens group has a first sub lens unit and a second sub lens unit in order from the object side to the image side. lens. The telephoto lens according to claim 5, wherein the first lens group has a third sub lens unit on the image side of the second sub lens unit. The telephoto lens according to claim 6, wherein both of the refractive power of the first sub lens unit and the refractive power of the third sub lens unit are positive refractive power. The telephoto lens according to any one of claims 1 to 7, wherein a stop is disposed between the first lens group and the second lens group. The telephoto lens according to any one of claims 1 to 8, wherein the third lens group consists of one lens component.
  Here, the lens component is a single lens or a cemented lens, and is a lens having two optically effective surfaces in air contact. A telephoto lens according to any one of claims 1 to 9,
An image pickup device having an image pickup surface and converting an image formed on the image pickup surface by the telephoto lens into an electric signal;