JP2008015432A - Zoom lens and optical equipment having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens having a wide angle of view and a high variable power ratio, made compact and having high optical performance, and optical equipment having the same. <P>SOLUTION: The zoom lens has a first negative lens group G1, an aperture stop S, a second positive lens group G2 and a third positive lens group G3 in order from an object side along an optical axis. When varying power from a wide angle end state to a telephoto end state, at least the first lens group and the second lens group move. The first lens group is constituted of a negative meniscus lens turning its convex surface to the object side, a negative lens and a positive lens in order from the object side, and at least one lens surface of the negative lens is aspherical. The second lens group is constituted of a first positive lens, a second positive lens, a negative lens and a third positive lens in order from the object side, and at least one surface out of the respective lens surfaces included in the second lens group is aspherical. The zoom lens 2 satisfies a predetermined condition, and the optical equipment 1 has the zoom lens 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a zoom lens suitable for a video camera, an electronic still camera, and the like using a solid-state imaging device and an optical apparatus having the same.

  2. Description of the Related Art In recent years, imaging devices such as digital still cameras and digital video cameras that use solid-state imaging devices have been rapidly increasing in performance and size. In these photographing apparatuses, a zoom lens is generally used as an imaging lens. With the zoom lens, a photographer can easily perform photographing at an angle of view that is optimal for photographing conditions.

  Among these zoom lenses, especially those mounted on small-sized imaging devices are mostly those with a zoom ratio of about 3 times, and most of them have a lens group having negative refractive power arranged closest to the object side. In this type, one or more lens groups having positive refractive power are arranged on the image plane side (negative leading type). The reason why the negative leading type is widely used is that even with a simple lens configuration consisting of about 2 to 3 lens groups, a zoom ratio of about 3 times can be obtained, and relatively good aberration correction is possible. This is because of this. In addition, since the entrance pupil position can be moved to the object side, the diameter of the first lens group can be reduced, and the exit pupil position can be sufficiently distant from the image sensor.

  Since the negative leading zoom lens has a reverse telephoto type refractive power arrangement as a whole, it is suitable for widening the angle of view compared to the positive leading zoom lens. Therefore, in order to provide a zoom lens that has an angle of view that can support full-scale wide-angle shooting and that has optical performance that is compatible with imaging devices that are becoming more sophisticated year by year, the negative leading zoom lens type should be adopted. Is reasonable. On top of this, the refractive power arrangement of each lens group constituting the zoom lens, the lens configuration in each lens group, the position of the aspherical surface, the glass material of each lens, etc. are appropriately selected, and good aberrations even for a wide angle of view It is necessary to realize the correction.

On the other hand, the negative leading zoom lens tends to be longer in total length than the focal length, and aberration correction is extremely difficult if it is forced to be compact. Therefore, conventionally, when a negative leading zoom lens is used in a small image pickup device, it is almost always possible to achieve both compactness of the full length and good optical performance by limiting the angle of view on the wide angle side to about 60 degrees. (For example, see Patent Document 1). In addition, there is a lens that achieves a wide zoom ratio in the wide-angle end state and achieves a high zoom ratio by moving three lens groups at the time of zooming (see, for example, Patent Document 2).
JP 2002-196240 A JP-A-2005-99092

  The conventional zoom lens cannot be said to make full use of the ability of a negative leading zoom lens that is inherently suitable for a wide angle of view, and has a drawback that wide-angle shooting cannot be performed.

  In addition, even if a high angle of view is achieved, the zoom lens has a disadvantage that the overall length of the zoom lens and the outer diameter of the first lens group are large, and that miniaturization cannot be achieved.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and includes a wide angle of view, allows wide-angle shooting, and has a high zoom ratio, despite the simple lens configuration. It is an object to provide a zoom lens suitable for a digital still camera and a video camera that is extremely compact and has high optical performance.

In order to solve the above problems, the present invention includes, in order from the object side along the optical axis, a first lens group having a negative refractive power, an aperture stop, and a second lens group having a positive refractive power; A third lens group having a positive refractive power, and the distance between the first lens group and the second lens group decreases upon zooming from the wide-angle end state to the telephoto end state, and the second lens At least the first lens group and the second lens group move along the optical axis so that the distance between the group and the third lens group increases, and the first lens group is an object along the optical axis. In order from the side, a negative meniscus lens having a convex surface facing the object side, a negative lens, and a positive lens, at least one lens surface of the negative lens is an aspheric surface, and the second lens group includes a light lens In order from the object side along the axis, the first positive lens, the second positive lens, and the negative lens And a third positive lens, and at least one of the lens surfaces included in the second lens group is an aspherical surface, and satisfies the following conditions. .
0.50 <ft × Ymax / {fw × (fw + ft)} <0.70
1.00 <| f1 | / (fw × ft) ^1/2 <1.40
1.80 <f2 / fw <2.45
Where Ymax is the maximum image height of the zoom lens, fw is the focal length of the entire zoom lens system in the wide-angle end state, ft is the focal length of the entire zoom lens system in the telephoto end state, and f1 is the focal length of the first lens group. The focal length, f2, is the focal length of the second lens group.

  The present invention also provides an optical apparatus comprising the zoom lens.

In addition, the present invention has a first lens group having a negative refractive power, an aperture stop, a second lens group having a positive refractive power, and a positive refractive power in order from the object side along the optical axis. A third lens group, and the first lens group includes, in order from the object side along the optical axis, a negative meniscus lens having a convex surface facing the object side, a negative lens, and a positive lens. At least one lens surface of the negative lens is aspherical, and the second lens group includes a first positive lens, a second positive lens, a negative lens, and a third positive lens in order from the object side along the optical axis. And at least one of the lens surfaces included in the second lens group is an aspherical surface, satisfies the following conditions, and performs zooming from the wide-angle end state to the telephoto end state. An interval between one lens group and the second lens group is reduced, and the second lens group As serial interval between the third lens group is increased, to provide a scaling method characterized by moving at least the second lens group and the first lens group along the optical axis.
0.50 <ft × Ymax / {fw × (fw + ft)} <0.70
1.00 <| f1 | / (fw × ft) ^1/2 <1.40
1.80 <f2 / fw <2.45
Where Ymax is the maximum image height of the zoom lens, fw is the focal length of the entire zoom lens system in the wide-angle end state, ft is the focal length of the entire zoom lens system in the telephoto end state, and f1 is the focal length of the first lens group. The focal length, f2, is the focal length of the second lens group.

  According to the present invention, despite a simple lens configuration, a wide angle of view is included, wide-angle shooting is possible, and at the same time a high zoom ratio is achieved, the entire zoom lens is extremely compact, and high optical performance is achieved. It is possible to provide a zoom lens suitable for a digital still camera or a video camera having

  Embodiments of the present invention will be described below with reference to the drawings.

  1A and 1B show an electronic still camera equipped with a zoom lens according to an embodiment to be described later. FIG. 1A shows a front view and FIG. 1B shows a rear view. FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG.

  1 and 2, in the electronic still camera 1 according to the embodiment, when a power button (not shown) is pressed, a shutter (not shown) of the photographing lens 2 is opened and light from a subject (not shown) is collected by the photographing lens 2. The light is emitted and imaged on an image sensor C (for example, CCD or CMOS) disposed on the image plane I. The subject image formed on the image sensor C is displayed on the liquid crystal monitor 3 disposed behind the electronic still camera 1. The photographer determines the composition of the subject image while looking at the liquid crystal monitor 3, and then presses the release button 4 to photograph the subject image with the image sensor C, and records and saves it in a memory (not shown).

  The photographing lens 2 includes a zoom lens 2 according to an embodiment described later. The electronic still camera 1 also zooms the auxiliary light emitting unit 5 that emits auxiliary light when the subject is dark and the zoom lens 2 that is the photographing lens 2 from the wide-angle end state (W) to the telephoto end state (T). A wide (W) -tele (T) button 6 and a function button 7 used for setting various conditions of the electronic still camera 1 are arranged.

  In this way, an electronic still camera 1 including a zoom lens 2 according to an embodiment described later is configured.

  Next, the zoom lens according to the embodiment will be described. First, the basic structure of the zoom lens according to the embodiment will be described.

  The zoom lens according to the embodiment includes, in order from the object side along the optical axis, a first lens group having a negative refractive power, an aperture stop, a second lens group having a positive refractive power, and positive refraction. And a third lens group having power.

  In the zoom lens according to the embodiment, the second lens group is a zoom unit and a master lens group, and the first lens group is a compensator group. Further, the third lens group is fixed or moved during zooming, and the exit pupil position of the entire zoom lens system is optimized with respect to the image pickup device, and remains uncorrected by the first lens group and the second lens group. Correct aberrations.

  Next, the configuration of the first lens group will be described. It is desirable that the first lens group is composed of a negative meniscus lens having a convex surface directed toward the object side, a negative lens, and a positive lens in order from the object side along the optical axis. With this configuration, it is possible to correct lower coma, astigmatism, distortion, and spherical aberration and lower coma in the telephoto end state. Further, since the entrance pupil moves to the object side, the height of the principal ray passing through the negative meniscus lens is reduced, and the outer diameter of the negative meniscus lens can be reduced. Furthermore, since the rear principal point of the first lens group moves to the image plane side, if the second lens group is a telephoto type, the distance between the first lens group and the second lens group is reduced in the telephoto end state. In addition, the back focus of the second lens group can be reduced, and the overall length of the zoom lens can be shortened.

  In addition, it is desirable that at least one of the lens surfaces of the negative meniscus lens included in the first lens group is aspherical. By making at least one surface aspherical, it is possible not only to satisfactorily correct negative distortion in the wide-angle end state but also to increase the refractive power of the entire first lens unit, which is advantageous for making the zoom lens compact. . In order to make the effect of the embodiment more reliable, it is desirable that the lens surface on the image surface side of the negative meniscus lens is aspherical.

  Next, the configuration of the second lens group will be described. The negative leading zoom lens has a reverse telephoto power arrangement as a whole. As in the case of the single focus lens, this refractive power arrangement is a structure that tends to generate negative distortion and lateral chromatic aberration. Therefore, it is necessary to adopt a lens type having a high degree of freedom in correcting these aberrations for the second lens group.

  The lens type that satisfies this condition with the simplest configuration is a triplet composed of three lenses, positive, negative, and positive. In this triplet, distortion and lateral chromatic aberration can be controlled relatively freely by appropriately selecting the refractive power and dispersion of each lens.

  However, when the second lens group made of triplets is arranged behind the first lens group having negative refractive power as in the negative leading zoom lens, the second lens group is diverged by the first lens group. Since the light beam is incident, it is difficult to correct the spherical aberration. Further, in order to increase the ability to correct the negative distortion generated in the first lens group, the entire second lens group needs to have a telephoto refractive power arrangement. Since strong refractive power concentrates on the positive lens located, it is further disadvantageous for correction of spherical aberration. If the second lens group is formed of a triplet and spherical aberration is to be corrected satisfactorily, the refractive power of the entire second lens group must be weakened. Therefore, when the second lens group is composed of triplets, it is difficult to achieve both compactness and high performance of the entire zoom lens.

  For the above reason, in the zoom lens according to the embodiment, in order to improve the spherical aberration correction capability of the second lens group, the positive lens located closest to the object side of the triplet is divided into two pieces, and the object along the optical axis is divided. In order from the side, it is desirable to form the second lens group by four lenses, which are a first positive lens, a second positive lens, a negative lens, and a third positive lens. As a result, the refractive power of the entire second lens group can be increased, and the entire zoom lens can be made compact.

  More preferably, among the lenses included in the second lens group, it is desirable that the second positive lens and the negative lens are cemented. As a result, the sensitivity of the lens to the eccentricity error can be greatly relaxed.

  Furthermore, it is desirable that at least one of the lens surfaces included in the second lens group is aspherical. By using an aspherical surface, not only can spherical aberration generated in the second lens group be corrected more satisfactorily, but also the refractive power of the entire second lens group can be increased, which is advantageous for downsizing. In order to secure the effect of the embodiment, it is more preferable that one or both of the lens surfaces of the first positive lens are aspherical.

In the zoom lens according to the embodiment, it is preferable that the following conditional expressions (1) to (3) are satisfied.
(1) 0.50 <ft × Ymax / {fw × (fw + ft)} <0.70
(2) 1.00 <| f1 | / (fw × ft) ^1/2 <1.40
(3) 1.80 <f2 / fw <2.45
Where Ymax is the maximum image height of the zoom lens, fw is the focal length of the entire zoom lens system in the wide-angle end state, ft is the focal length of the entire zoom lens system in the telephoto end state, f1 is the focal length of the first lens group, and f2 Is the focal length of the second lens group.

  In the zoom lens according to the embodiment, it is desirable to satisfy the conditional expression (1) in order to include a field angle exceeding 70 degrees at the wide angle end of the negative leading zoom lens and to perform favorable aberration correction.

  If the lower limit of conditional expression (1) is not reached, it becomes impossible to ensure a sufficient angle of view in the wide-angle end state, or it becomes difficult to ensure a sufficient zoom ratio. Therefore, it is not preferable because it is contrary to the wide angle and high zoom ratio of the zoom lens which is the object of the present invention. If the upper limit value of conditional expression (1) is exceeded, the angle of view at the wide-angle end state becomes too wide, making it difficult to correct distortion, and the focal length at the telephoto end state becomes too long. Correction becomes difficult. Accordingly, it is difficult to maintain good optical performance, which is not preferable.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.54. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (1) to 0.56. In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (1) to 0.65. In order to further secure the effect of the embodiment, it is more preferable to set the upper limit of conditional expression (1) to 0.62.

  In the zoom lens according to the embodiment, it is desirable that the conditional expression (2) is satisfied in order to perform good aberration correction while keeping the entire length of the zoom lens compact. Conditional expression (2) defines an appropriate range of the focal length of the first lens group. When the lower limit value of conditional expression (2) is not reached, the back focus of the second lens group becomes long in the telephoto end state, and the entire length of the zoom lens becomes remarkably long. Further, it is not preferable because it is difficult to correct the lower coma aberration and distortion in the wide-angle end state, and the spherical aberration and lower coma aberration in the telephoto end state. If the upper limit of conditional expression (2) is exceeded, the air gap between the first lens group and the second lens group is increased in the wide-angle end state in order to ensure the amount of movement of the two lens groups necessary for zooming. The need arises and the overall length is significantly increased. Furthermore, the outer diameter of the negative meniscus lens located closest to the object side of the first lens group increases. In order to reduce the outer diameter of the negative meniscus lens, it is indispensable to remarkably increase the refractive power of each lens constituting the first lens group. However, with such means, lower coma aberration at the wide-angle end state, telephoto end This is not preferable because correction of spherical aberration in the state becomes difficult.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (2) to 1.15. In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (2) to 1.32.

  Conditional expression (3) defines an appropriate range of the focal length of the second lens group. If the lower limit of conditional expression (3) is not reached, the back focus of the second lens group is reduced and the amount of movement during zooming is reduced, which is advantageous for downsizing, but occurs in the second lens group. Since correction of spherical aberration becomes difficult, it is not preferable. If the upper limit value of conditional expression (3) is exceeded, the amount of movement of the second lens unit during zooming will become extremely large, which is not preferable because the total length of the zoom lens becomes excessive. Further, it is not preferable because it is difficult to correct the lower coma aberration and distortion in the wide-angle end state, and the spherical aberration and lower coma aberration in the telephoto end state. Furthermore, the F number fluctuates greatly between the wide-angle end state and the telephoto end state, which is not preferable in that sufficient brightness cannot be secured in the telephoto end state.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (3) to 2.00. In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (3) to 2.30.

In the zoom lens according to the embodiment, it is preferable that the following conditional expression (4) is satisfied in order to satisfactorily correct aberrations in the second lens group.
(4) 0.35 <n23-n24 <0.65
However, n23 is the refractive index with respect to the d-line (λ = 587.6 nm) of the negative lens material of the second lens group, and n24 is the d-line (λ = 587.6 nm) of the third positive lens material of the second lens group. Is the refractive index.

  Conditional expression (4) defines an appropriate range of the refractive index difference between the negative lens and the third positive lens in the second lens group. If the lower limit of conditional expression (4) is not reached, the upper coma in the wide-angle end state from the intermediate focal length state to the telephoto end state is corrected while correcting the spherical aberration variation in the second lens group due to zooming. Since it becomes difficult to correct the aberration, it is not preferable. If the upper limit of conditional expression (4) is exceeded, the use of existing glass materials tends to increase the partial dispersion ratio of the negative lens glass material, making it difficult to correct the secondary spectrum of longitudinal chromatic aberration in the telephoto end state. Thus, it becomes difficult to maintain high optical performance.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (4) to 0.39. In order to further secure the effect of the embodiment, it is more preferable to set the lower limit of conditional expression (4) to 0.44. In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (4) to 0.60.

In the zoom lens according to the embodiment, it is preferable that the following conditional expression (5) is satisfied in order to satisfactorily correct the lateral chromatic aberration.
(5) 47.0 <ν24−ν23 <75.0
Where ν23 is the Abbe number for the d-line (λ = 587.6 nm) of the negative lens material of the second lens group, and ν24 is the d-line (λ = 587.6 nm) of the third positive lens material of the second lens group. Is the Abbe number.

  Conditional expression (5) defines an appropriate range for the difference in Abbe number between the negative lens and the third positive lens in the second lens group. When the lower limit value of conditional expression (5) is not reached, lateral chromatic aberration in the telephoto end state deteriorates. If this is corrected without increasing the total thickness of the second lens group, it becomes difficult to correct the difference due to the wavelength of the lower coma aberration in the wide-angle end state and the difference due to the wavelength of the upper coma aberration in the intermediate focal length state. It is not preferable. If the upper limit of conditional expression (5) is exceeded, the partial dispersion ratio of the glass material of the negative lens will increase, making it difficult to correct the secondary spectrum of axial chromatic aberration in the telephoto end state, and maintaining high optical performance. It becomes difficult. By satisfying conditional expression (5), the chromatic aberration of magnification can be maintained without increasing the total thickness of the second lens group while maintaining the refractive power arrangement in the second lens group in an appropriate state for correcting spherical aberration and coma. Can be corrected.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (5) to 50.0. In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (5) to 70.0.

  In the zoom lens according to the embodiment, it is desirable that the focusing from the object at infinity to the object at finite distance is performed by moving the third lens group along the optical axis. By using the third lens group for focusing, it is possible to shoot an object at a close distance in the wide-angle end state without reducing the amount of light reaching the periphery of the screen. In the negative leading zoom, focusing can be performed using the first lens unit having a negative refractive power, but the amount of light reaching the periphery of the screen at the time of photographing a very close object in the wide-angle end state is small. There is a problem of significant reduction. To prevent this, it is necessary to increase the outer diameter of the first lens group, but it is not preferable because it is difficult to correct the lower coma aberration in the wide-angle end state.

In the zoom lens according to the embodiment, the third lens group includes one positive lens, and at least one of the lens surfaces of the positive lens in the third lens group is an aspheric surface. It is desirable to satisfy Formula (6).
(6) −0.40 <(Rb + Ra) / (Rb−Ra) <1.35
Where Ra is the radius of curvature of the object side surface of the positive lens of the third lens group, and Rb is the radius of curvature of the image side surface of the positive lens of the third lens group.

  By configuring the third lens group with one positive lens, not only is it advantageous from the viewpoint of cost, but also the thickness when retracted can be reduced. In addition, since at least one of the lens surfaces included in the third lens group is aspherical, it is effective for astigmatism that cannot be corrected by the first lens group and the second lens group. Correction becomes possible.

  Conditional expression (6) defines an appropriate range of the shape of the positive lens constituting the third lens group. The positive lens of the third lens group optimizes the position of the exit pupil of the entire zoom lens system with respect to the image sensor, and corrects astigmatism that could not be corrected by the first lens group and the second lens group. Is going. Further, as described above, focusing from an object at infinity to an object at finite distance is performed by moving the positive lens on the optical axis. Therefore, in order to correct astigmatism satisfactorily and not cause aberration fluctuations due to focusing, it is necessary to set the shape of the positive lens appropriately.

  If the lower limit value of conditional expression (6) is not reached, it is difficult to correct astigmatism in the intermediate focal length state, and it becomes difficult to correct distortion in the wide-angle end state. Furthermore, when photographing an object at a close distance in all focal length states, the image plane varies significantly positive and astigmatism increases, which is not preferable. When the upper limit of conditional expression (6) is exceeded, the positive lens has a meniscus shape with the convex surface facing the object side, which is advantageous for correcting distortion at the wide-angle end state, but is not effective at the intermediate focal length state. It is not preferable since it is difficult to correct the point aberration, and the image plane changes significantly negatively at the time of photographing an object at a close distance in the telephoto end state. Further, a ghost attributed to the image side surface of the positive lens is generated, which is not preferable.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (6) to −1.00. In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (6) to 1.00.

In the zoom lens according to the embodiment, it is desirable to satisfy the following conditional expression (7) in order to satisfactorily correct lateral chromatic aberration in the telephoto end state.
(7) 71.0 <ν31 <95.0
Where ν31 is the Abbe number with respect to the d-line (λ = 587.6 nm) of the material of the positive lens of the third lens group.

  Conditional expression (7) defines an appropriate range of the Abbe number of the positive lens constituting the third lens group. Since the third lens group has a positive refractive power and a large principal ray height, it tends to generate negative lateral chromatic aberration. Therefore, it is necessary to use a low dispersion glass material for the third lens group to reduce the occurrence of lateral chromatic aberration. If the lower limit of conditional expression (7) is not reached, it is difficult to correct lateral chromatic aberration in the telephoto end state, which is not preferable. If the upper limit of conditional expression (7) is exceeded, it is necessary to use fluorite for the positive lens with currently available lens materials, but it is extremely difficult to guarantee the shape accuracy of the refracting surface using an inexpensive processing method. Therefore, it is not preferable. Also, the Petzval sum becomes positive, and it becomes impossible to correct curvature of field and astigmatism at the same time.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (7) to 80.0. In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (7) to 92.0.

In the zoom lens according to the embodiment, it is preferable that the following conditional expression (8) is satisfied in order to realize better aberration correction.
(8) 0.0060 <fL11 / (f1 × ν12) <0.0130
Here, fL11 is the focal length of the negative meniscus lens, f1 is the focal length of the first lens group, and ν12 is the Abbe number with respect to the d-line (λ = 587.6 nm) of the material of the negative lens of the first lens group.

  Conditional expression (8) shows the focal length of the entire first lens unit, the focal length of the negative meniscus lens disposed closest to the object side of the first lens unit, and the second negative lens from the object side of the first lens unit. An appropriate range is specified for the Abbe number. If the lower limit of conditional expression (8) is not reached, the refractive power of the negative meniscus lens becomes too strong, making it difficult to correct astigmatism, distortion, and lateral chromatic aberration in the wide-angle end state, which is not preferable. In addition, when an existing glass material is used, the refractive index of the negative lens of the first lens group becomes too low, the Petzval sum becomes extremely negative, and it becomes difficult to correct downward coma in the telephoto end state. . When the upper limit value of conditional expression (8) is exceeded, the difference due to the wavelength of the lower coma aberration in the wide-angle end state, the difference due to the wavelength of the upper coma aberration in the telephoto end state increases, and correction of the lateral chromatic aberration in the telephoto end state Is not preferable because it becomes difficult.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit of conditional expression (8) to 0.0080. In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (8) to 0.0115.

In the zoom lens according to the embodiment, it is preferable that the following conditional expression (9) is satisfied in order to satisfactorily correct downward coma in the wide-angle end state and the telephoto end state.
(9) −7.0 <(Rd + Rc) / (Rd−Rc) <− 1.0
Where Rc is the radius of curvature of the image side surface of the negative lens of the first lens group, and Rd is the radius of curvature of the object side surface of the positive lens of the first lens group.

  Conditional expression (9) defines an appropriate range for the shape of the air lens formed between the negative lens and the positive lens of the first lens group. If the lower limit of conditional expression (9) is not reached, it is not preferable because it is difficult to correct downward coma and spherical aberration in the telephoto end state. Exceeding the upper limit value of conditional expression (9) is not preferable because it becomes difficult to correct downward coma and distortion in the wide-angle end state.

  In order to secure the effect of the embodiment, it is preferable to set the lower limit value of conditional expression (9) to −5.5. In order to secure the effect of the embodiment, it is preferable to set the upper limit of conditional expression (9) to −2.5.

  In the zoom lens according to the embodiment, it is desirable that the third lens group is fixed during zooming from the wide-angle end state to the telephoto end state. By fixing the position of the third lens group at the time of zooming, it is possible to prevent an increase in astigmatism due to the eccentricity of the third lens group.

  In the embodiment, in order from the object side along the optical axis, the first lens group having negative refractive power, the aperture stop, the second lens group having positive refractive power, and the positive refractive power are set. The first lens group is composed of, in order from the object side along the optical axis, a negative meniscus lens having a convex surface on the object side, a negative lens, and a positive lens. At least one lens surface of the negative lens is an aspherical surface, and the second lens group includes a first positive lens, a second positive lens, a negative lens, and a third lens in order from the object side along the optical axis. And at least one of the lens surfaces included in the second lens group is an aspherical surface, satisfies the above conditional expressions (1) to (3), and is in the wide-angle end state to the telephoto end state. During zooming, the distance between the first lens group and the second lens group decreases. , And the interval between the third lens group and the second lens group increases, zooming method for moving at least the second lens group and the third lens group along the optical axis is desirable. By adopting such a zooming method, the drive mechanism can be simplified and the entire length of the zoom lens can be shortened.

  In the zoom lens according to the embodiment, among the lens groups constituting the zoom lens, one lens group or a part of the lenses may be moved in a direction substantially perpendicular to the optical axis. it can. Thereby, it is possible to move the image on the image plane, and it is possible to realize a so-called anti-vibration lens.

(Example)
Hereinafter, each implementation of the zoom lens according to the present embodiment will be described with reference to the accompanying drawings.

(First embodiment)
FIG. 3 is a diagram illustrating a lens configuration of the zoom lens according to the first example, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state.

  In FIG. 3, the zoom lens according to the first example includes, in order from the object side along the optical axis, a first lens group G1 having a negative refractive power, an aperture stop S, and a first lens having a positive refractive power. A second lens group G2 and a third lens group G3 having a positive refractive power, and at the time of zooming from the wide-angle end state W to the telephoto end state T, the first lens group G1 and the second lens group G2 The first lens group G1 and the second lens group G2 move along the optical axis so that the distance decreases and the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 moves. It is fixed and configured.

  The first lens group G1 has, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. The lens surface on the image plane I side of the negative meniscus lens L11 is an aspherical surface.

  The second lens group G2 includes, in order from the object side along the optical axis, a biconvex positive lens L21, a biconvex positive lens L22, a biconcave negative lens L23, and a biconvex positive lens. The biconvex positive lens L22 and the biconcave negative lens L23 are cemented together, and the surface on the image plane I side of the biconvex positive lens L21 is an aspherical surface. .

  The third lens group G3 comprises only one biconvex positive lens L31, and the object side surface of the biconvex positive lens L31 is an aspherical surface.

  Focusing from an object at infinity to an object at finite distance is performed by moving the third lens group G3 along the optical axis.

  The aperture stop S is disposed closer to the object side than the biconvex positive lens L21 closest to the object side of the second lens group G2, and the second lens group upon zooming from the wide-angle end state W to the telephoto end state T. Moves together with G2.

  The filter group FL disposed between the third lens group G3 and the image plane I is composed of a low-pass filter, an infrared cut filter, and the like.

  Table 1 below provides values of specifications of the zoom lens according to the first example. In the table, in [Overall specifications], f is the focal length, FNO is the F number, 2ω is the angle of view (unit: degree), and Ymax is the maximum image height. In [lens specifications], the first column is the lens surface number when counted from the object side, the second column r is the radius of curvature of the lens surface, the third column d is the distance on the optical axis of the lens surface, and the fourth The column ν indicates the Abbe number with respect to the d-line (λ = 587.6 nm), and the fifth column n indicates the refractive index with respect to the d-line (λ = 587.6 nm). In addition, * attached | subjected to the left of the 1st column has shown that the lens surface is an aspherical surface. B.f. is back focus. In addition, although the refractive index of air is 1.000000, description is abbreviate | omitted in the table | surface and "infinity" of the curvature radius r column shows that it is a plane.

The aspherical surface has a height in the direction perpendicular to the optical axis as y, a distance (sag amount) along the optical axis from the tangent plane of each aspherical surface at the height y to each aspherical surface as S (y), When the radius of curvature of the reference spherical surface (paraxial radius of curvature) is R, the conic constant is κ, and the nth-order aspherical coefficient is Cn, the following formula is used.
S (y) = (y ² / R) / {1+ (1-κy ² / R ² ) ^1/2 }
+ C4y ⁴ + C6y ⁶ + C8y ⁸ + C10y ¹⁰
[Aspherical data] shows the conic constant κ and the aspherical coefficient Cn of each aspherical surface. “En” (n is an integer) in the aspherical data column indicates “× 10 ⁻ⁿ ”.

  The [variable interval data] includes a focal length f, a magnification β, a distance D0 from the object to the lens surface closest to the object, and variable intervals in each of the wide-angle end state, the intermediate focal length state, and the telephoto end state. Indicates the value. In [Conditional Expression Corresponding Value], the corresponding value of each conditional expression is shown.

  In all the following specification values, “mm” is generally used as the focal length f, radius of curvature r, surface interval d and other lengths, etc. unless otherwise specified, but the optical system is proportional. Even if it is enlarged or proportionally reduced, the same optical performance can be obtained. Further, the unit is not limited to “mm”, and other appropriate units may be used. Further, the description of these symbols is the same in the other examples described later, and the subsequent description is omitted.

(Table 1)
[Overall specifications]
f = 6.077-21.20
FNO = 2.80-5.59
2ω = 77.3 ° ~ 24.3 °
Ymax = 4.551

[Lens specifications]
rd ν n
1) 37.5903 1.6000 42.71 1.820800
* 2) 6.4738 3.3000
3) 95.8076 1.1000 65.47 1.603000
4) 22.9036 0.6000
5) 13.8110 2.1000 23.78 1.846660
6) 43.5163 (d6)

7) ∞ 0.4000 Aperture stop S
8) 9.4737 1.9000 59.44 1.583130
* 9) -50.4251 0.1000
10) 7.9153 2.9000 52.29 1.755000
11) -35.8203 0.9500 31.31 1.903660
12) 5.1959 1.0000
13) 92.1828 1.4000 91.20 1.456000
14) -14.5991 (d14)

* 15) 18.2787 2.0000 82.56 1.497820
16) -71.4762 (d16)

17) ∞ 2.0000 70.70 1.544400
18) ∞ 0.5000
19) ∞ 0.5000 64.12 1.516800
20) ∞ (Bf)


[Aspherical data]
(Second side)
κ = 0.5814
C4 = -5.00140E-05
C6 = 2.39130E-07
C8 = -3.42370E-08
C10 = 0.00000E + 00

(9th page)
κ = -6.9700
C4 = 1.42020E-04
C6 = 5.22860E-07
C8 = 0.00000E + 00
C10 = 0.00000E + 00

(15th page)
κ = -4.8910
C4 = 1.21570E-04
C6 = 0.00000E + 00
C8 = 0.00000E + 00
C10 = 0.00000E + 00

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 6.077 11.30 21.20
D0 ∞ ∞ ∞
d6 19.58192 8.02771 1.74989
d14 5.48877 11.77081 23.67818
d16 1.96508 1.96508 1.96508

Close-up shooting (shooting distance 300mm)
Wide-angle end state Intermediate focal length state Telephoto end state β -0.02340 -0.04226 -0.07671
D0 249.6138 254.8862 249.2564
d6 19.58192 8.02771 1.74989
d14 5.11895 10.59508 20.20233
d16 2.33490 3.14080 5.44092

[Values for conditional expressions]
(1) Ymax / fw = 0.74889
(2) | f1 | / (fw × ft) ^1/2 = 1.25199
(3) f2 / fw = 2.22431
(4) n23-n24 = 0.44766
(5) ν24−ν23 = 59.89
(6) (Rd + Rc) / (Rd−Rc) = 0.59270
(7) ν31 = 82.56
(8) fL11 / (f1 × ν12) = 0.01048
(9) (Rb + Ra) / (Rb−Ra) = − 4.03785

  4A to 4C are graphs showing various aberrations when the zoom lens according to Example 1 is focused at infinity, in which FIG. 4A is a wide-angle end state, FIG. 4B is an intermediate focal length state, c) shows aberration diagrams in the telephoto end state. FIGS. 5A to 5C are graphs showing various aberrations when the zoom lens according to the first example is in close focus (shooting distance 300 mm), where FIG. 5A is a wide-angle end state, and FIG. Is an intermediate focal length state, and (c) is an aberration diagram in the telephoto end state.

  In each aberration diagram, FNO is the F number, NA is the numerical aperture, Y is the image height, A is the half field angle, H0 is the object height, d is the d-line (λ = 587.6 nm), g Indicates an aberration curve of g-line (λ = 435.8 nm), C indicates a C-line (λ = 656.3 nm), and F indicates an F-line (λ = 486.1 nm). Further, in the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. In addition, in the various aberration diagrams of the following examples, the same reference numerals as those of the present example are used, and description thereof is omitted.

  From each aberration diagram, it can be seen that the zoom lens according to the first example has excellent optical performance with various aberrations corrected well in each focal length state from the wide-angle end state W to the telephoto end state T.

(Second embodiment)
FIG. 6 is a diagram illustrating the lens configuration of the zoom lens according to the second example, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state.

  In FIG. 6, the zoom lens according to the second example includes, in order from the object side along the optical axis, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens having a positive refractive power. A lens group G2 and a third lens group G3 having a positive refractive power, and the distance between the first lens group G1 and the second lens group G2 during zooming from the wide-angle end state W to the telephoto end state T The first lens group G1 and the second lens group G2 move along the optical axis so that the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 is fixed. Has been configured.

  The first lens group G1 has, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. The lens surface on the image plane I side of the negative meniscus lens L11 is an aspherical surface.

  The second lens group G2 includes, in order from the object side along the optical axis, a biconvex positive lens L21, a biconvex positive lens L22, a biconcave negative lens L23, and a biconvex positive lens. The biconvex positive lens L22 and the biconcave negative lens L23 are cemented together, and the surface on the image plane I side of the biconvex positive lens L21 is an aspherical surface. .

  The third lens group G3 comprises only one biconvex positive lens L31, and the object side surface of the biconvex positive lens L31 is an aspherical surface.

  Focusing from an object at infinity to an object at finite distance is performed by moving the third lens group G3 along the optical axis.

  The aperture stop S is disposed closer to the object side than the biconvex positive lens L21 closest to the object side of the second lens group G2, and the second lens group upon zooming from the wide-angle end state W to the telephoto end state T. Moves together with G2.

  The filter group FL disposed between the third lens group G3 and the image plane I is composed of a low-pass filter, an infrared cut filter, and the like.

  Table 2 below shows values of specifications of the zoom lens according to the second example.

(Table 2)
[Overall specifications]
f = 6.077-20.485
FNO = 2.83 ~ 5.51
2ω = 77.3 ° -25.1 °
Ymax = 4.551

[Lens specifications]
rd ν n
1) 37.0466 1.6000 42.71 1.820800
* 2) 6.4412 3.3000
3) 72.0445 1.1000 65.47 1.603000
4) 20.7853 0.6000
5) 13.4233 2.1000 23.78 1.846660
6) 40.4466 (d6)

7) ∞ 0.4000 Aperture stop S
8) 9.1580 1.9000 59.44 1.583130
* 9) -64.7071 0.1000
10) 8.2132 3.1000 54.66 1.729160
* 11) -22.2498 0.7500 32.35 1.850 260
12) 5.2345 1.0000
13) 53.9472 1.5000 82.56 1.497820
14) -17.2411 (d14)

* 15) 18.3720 2.0000 82.56 1.497820
16) -75.6004 (d16)

17) ∞ 2.0000 70.70 1.544400
18) ∞ 0.5000
19) ∞ 0.5000 64.12 1.516800
20) ∞ (Bf)

[Aspherical data]
(Second side)
κ = 0.5700
C4 = -4.58870E-05
C6 = 2.64780E-07
C8 = -3.23200E-08
C10 = 0.00000E + 00

(9th page)
κ = -6.9700
C4 = 1.47470E-04
C6 = 6.67710E-07
C8 = 0.00000E + 00
C10 = 0.00000E + 00

(15th page)
κ = -4.9050
C4 = 1.18860E-04
C6 = 0.00000E + 00
C8 = 0.00000E + 00
C10 = 0.00000E + 00

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 6.07700 11.30000 20.48500
D0 ∞ ∞ ∞
d6 19.41104 7.96913 2.00000
d14 5.52588 11.90048 23.11063
d16 2.05043 2.05043 2.05043

Close-up shooting (shooting distance 300mm)
Wide-angle end state Intermediate focal length state Telephoto end state β -0.02341 -0.04231 -0.07453
D0 249.5551 254.6227 249.3814
d6 19.41104 7.96913 2.00000
d14 5.15628 10.72348 19.80903
d16 2.42003 3.22742 5.35203

[Values for conditional expressions]
(1) Ymax / fw = 0.74889
(2) | f1 | / (fw × ft) ^1/2 = 1.25861
(3) f2 / fw = 2.22972
(4) n23−n24 = 0.52424
(5) ν24−ν23 = 50.21
(6) (Rd + Rc) / (Rd−Rc) = 0.60899
(7) ν31 = 82.56
(8) fL11 / (f1 × ν12) = 0.01058
(9) (Rb + Ra) / (Rb-Ra) =-4.64664

  FIGS. 7A to 7C are graphs showing various aberrations when the zoom lens according to Example 2 is in focus at infinity, where FIG. 7A is a wide-angle end state, FIG. 7B is an intermediate focal length state, c) shows aberration diagrams in the telephoto end state. FIGS. 8A to 8C are graphs showing various aberrations when the zoom lens according to Example 2 is in close focus (shooting distance 300 mm), where FIG. 8A is a wide-angle end state, and FIG. Is an intermediate focal length state, and (c) is an aberration diagram in the telephoto end state.

  From each aberration diagram, it can be seen that the zoom lens according to the second example has excellent optical performance with various aberrations corrected well in each focal length state from the wide-angle end state W to the telephoto end state T.

(Third embodiment)
FIG. 9 is a diagram illustrating the lens configuration of the zoom lens according to the third example, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state.

  In FIG. 9, the zoom lens according to the third example, in order from the object side along the optical axis, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens having a positive refractive power. A lens group G2 and a third lens group G3 having a positive refractive power, and the distance between the first lens group G1 and the second lens group G2 during zooming from the wide-angle end state W to the telephoto end state T The first lens group G1 and the second lens group G2 move along the optical axis so that the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 is fixed. Has been configured.

  The first lens group G1 has, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. The lens surface on the image plane I side of the negative meniscus lens L11 is an aspherical surface.

  The second lens group G2 includes, in order from the object side along the optical axis, a biconvex positive lens L21, a biconvex positive lens L22, a biconcave negative lens L23, and a biconvex positive lens. The biconvex positive lens L22 and the biconcave negative lens L23 are cemented together, and the surface on the image plane I side of the biconvex positive lens L21 is an aspherical surface. .

  The third lens group G3 comprises only one biconvex positive lens L31, and the object side surface of the biconvex positive lens L31 is an aspherical surface.

  Focusing from an object at infinity to an object at finite distance is performed by moving the third lens group G3 along the optical axis.

  The aperture stop S is disposed closer to the object side than the biconvex positive lens L21 closest to the object side of the second lens group G2, and the second lens group upon zooming from the wide-angle end state W to the telephoto end state T. Moves together with G2.

  The filter group FL disposed between the third lens group G3 and the image plane I is composed of a low-pass filter, an infrared cut filter, and the like.

  Table 3 below provides values of specifications of the zoom lens according to the third example.

(Table 3)
[Overall specifications]
f = 6.077-20.485
FNO = 2.83 ~ 5.52
2ω = 77.3 ° -25.1 °
Ymax = 4.551

[Lens specifications]
rd ν n
1) 37.2432 1.6000 42.71 1.820800
* 2) 6.4412 3.3000
3) 78.0975 1.1000 65.47 1.603000
4) 20.5136 0.6000
5) 13.4928 2.1000 23.78 1.846660
6) 43.1460 (d6)

7) ∞ 0.4000 Aperture stop S
8) 9.2266 1.9000 63.33 1.618000
* 9) -70.9986 0.1000
10) 8.3995 3.0000 52.29 1.755000
11) -13.7979 0.9000 34.02 1.898000
12) 5.3747 1.0000
13) 70.9259 1.5000 82.56 1.497820
14) -14.7270 (d14)

* 15) 18.3720 2.0000 82.56 1.497820
16) -75.6004 (d16)

17) ∞ 2.0000 70.70 1.544400
18) ∞ 0.5000
19) ∞ 0.5000 64.12 1.516800
20) ∞ (Bf)


[Aspherical data]
(Second side)
κ = 0.5700
C4 = -4.58870E-05
C6 = 2.64780E-07
C8 = -3.23200E-08
C10 = 0.00000E + 00

(9th page)
κ = -6.9700
C4 = 1.17940E-04
C6 = 1.35010E-07
C8 = 0.00000E + 00
C10 = 0.00000E + 00

(15th page)
κ = -4.9050
C4 = 1.18860E-04
C6 = 0.00000E + 00
C8 = 0.00000E + 00
C10 = 0.00000E + 00


[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 6.07700 11.30000 20.48500
D0 ∞ ∞ ∞
d6 19.41104 7.96913 2.00000
d14 5.47590 11.85049 23.06065
d16 2.05043 2.05043 2.05043

Close-up shooting (shooting distance 300mm)
Wide-angle end state Intermediate focal length state Telephoto end state β -0.02341 -0.04232 -0.0745
D0 249.5551 254.6227 249.3814
d6 19.41104 7.96913 2.00000
d14 5.10625 10.67337 19.75872
d16 2.42008 3.22755 5.35235

[Values for conditional expressions]
(1) Ymax / fw = 0.74889
(2) | f1 | / (fw × ft) ^1/2 = 1.25861
(3) f2 / fw = 2.22972
(4) n23−n24 = 0.40018
(5) ν24−ν23 = 48.54
(6) (Rd + Rc) / (Rd−Rc) = 0.60899
(7) ν31 = 82.56
(8) fL11 / (f1 × ν12) = 0.01057
(9) (Rb + Ra) / (Rb-Ra) =-4.84366

  FIGS. 10A to 10C are graphs showing various aberrations when the zoom lens according to Example 3 is in focus at infinity, where FIG. 10A is a wide-angle end state, FIG. 10B is an intermediate focal length state, c) shows aberration diagrams in the telephoto end state. FIGS. 11A to 11C are graphs showing various aberrations when the zoom lens according to Example 3 is in close focus (shooting distance 300 mm). FIG. 11A shows a wide-angle end state, and FIG. Is an intermediate focal length state, and (c) is an aberration diagram in the telephoto end state.

  From each aberration diagram, it can be seen that the zoom lens according to the third example has excellent optical performance with various aberrations corrected well in each focal length state from the wide-angle end state W to the telephoto end state T.

(Fourth embodiment)
FIG. 12 is a diagram illustrating a lens configuration of a zoom lens according to Example 4, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state.

  In FIG. 12, the zoom lens according to the fourth example, in order from the object side along the optical axis, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens having a positive refractive power. A lens group G2 and a third lens group G3 having a positive refractive power, and the distance between the first lens group G1 and the second lens group G2 during zooming from the wide-angle end state W to the telephoto end state T The first lens group G1 and the second lens group G2 move along the optical axis so that the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 is fixed. Has been configured.

  The first lens group G1 includes, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface directed toward the object side, a negative lens L12 having a biconcave shape, and a positive meniscus lens L13 having a convex surface directed toward the object side. The lens surface on the image plane I side of the negative meniscus lens L11 is an aspherical surface.

  The second lens group G2 includes, in order from the object side along the optical axis, a biconvex positive lens L21, a positive meniscus lens L22 having a convex surface facing the object side, and a negative meniscus lens L23 having a convex surface facing the object side. And a positive meniscus lens L22 having a convex surface facing the object side and a negative meniscus lens L23 having a convex surface facing the object side are cemented together to form a biconvex positive lens. The surface on the image plane I side of L21 is an aspherical surface.

  The third lens group G3 comprises only one biconvex positive lens L31, and the object side surface of the biconvex positive lens L31 is an aspherical surface.

  Focusing from an object at infinity to an object at finite distance is performed by moving the third lens group G3 along the optical axis.

  The aperture stop S is disposed closer to the object side than the biconvex positive lens L21 closest to the object side of the second lens group G2, and the second lens group upon zooming from the wide-angle end state W to the telephoto end state T. Moves together with G2.

  The filter group FL disposed between the third lens group G3 and the image plane I is composed of a low-pass filter, an infrared cut filter, and the like.

  Table 4 below shows values of specifications of the zoom lens according to the fourth example.

(Table 4)
[Overall specifications]
f = 6.077-21.20
FNO = 2.82-5.65
2ω = 77.3 ° ~ 24.2 °
Ymax = 4.551

[Lens specifications]
rd ν n
1) 34.6339 1.6000 42.71 1.820800
* 2) 6.4412 3.6000
3) -311.5920 1.1000 60.29 1.620410
4) 28.5001 0.4000
5) 15.1408 2.1000 23.78 1.846660
6) 69.0205 (d6)

7) ∞ 0.4000 Aperture stop S
8) 9.2039 1.9000 59.44 1.583130
* 9) -80.2026 0.1000
10) 7.6236 2.3910 37.16 1.834000
11) 116.2708 1.1429 25.46 2.000690
12) 5.1004 0.9000
13) 38.0884 1.5000 82.56 1.497820
14) -19.5816 (d14)

* 15) 13.0000 2.0000 82.56 1.497820
16) 97.3833 (d16)

17) ∞ 2.0000 70.70 1.544400
18) ∞ 0.5000
19) ∞ 0.5000 64.12 1.516800
20) ∞ (Bf)

[Aspherical data]
(Second side)
κ = 0.5525
C4 = -4.05780E-05
C6 = 6.67330E-07
C8 = -3.23200E-08
C10 = 0.00000E + 00

(9th page)
κ = -6.9700
C4 = 1.48600E-04
C6 = 4.32930E-07
C8 = 0.00000E + 00
C10 = 0.00000E + 00

(15th page)
κ = -2.8799
C4 = 2.02150E-04
C6 = 0.00000E + 00
C8 = 0.00000E + 00
C10 = 0.00000E + 00


[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 6.07700 11.30000 21.20000
D0 ∞ ∞ ∞
d6 19.41103 7.96912 1.75232
d14 6.28909 12.66368 24.74649
d16 1.60336 1.60336 1.60336

Close-up shooting (shooting distance 300mm)
Wide-angle end state Intermediate focal length state Telephoto end state β -0.02341 -0.04232 -0.07694
D0 249.5551 254.6227 248.7564
d6 19.41103 7.96912 1.75232
d14 5.91940 11.48643 21.25647
d16 1.97305 2.78062 5.09338

[Values for conditional expressions]
(1) Ymax / fw = 0.74889
(2) | f1 | / (fw × ft) ^1/2 = 1.23736
(3) f2 / fw = 2.22972
(4) n23−n24 = 0.50287
(5) ν24−ν23 = 57.10
(6) (Rd + Rc) / (Rd−Rc) = 1.30812
(7) ν31 = 82.56
(8) fL11 / (f1 × ν12) = 0.01168
(9) (Rb + Ra) / (Rb−Ra) = − 3.26671

  FIGS. 13A to 13C are graphs showing various aberrations when the zoom lens according to Example 4 is in focus at infinity, where FIG. 13A is a wide-angle end state, FIG. 13B is an intermediate focal length state, c) shows aberration diagrams in the telephoto end state. FIGS. 14A to 14C are graphs showing various aberrations when the zoom lens according to Example 4 is in close focus (shooting distance 300 mm), where FIG. 14A is a wide-angle end state, and FIG. Is an intermediate focal length state, and (c) is an aberration diagram in the telephoto end state.

  From each aberration diagram, it can be seen that the zoom lens according to the fourth example has excellent optical performance with various aberrations corrected well in each focal length state from the wide-angle end state W to the telephoto end state T.

(5th Example)
FIG. 15 is a diagram illustrating a lens configuration of a zoom lens according to Example 5. W represents a wide-angle end state, M represents an intermediate focal length state, and T represents a telephoto end state.

  In FIG. 15, the zoom lens according to the fifth example, in order from the object side along the optical axis, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens having a positive refractive power. A lens group G2 and a third lens group G3 having a positive refractive power, and the distance between the first lens group G1 and the second lens group G2 during zooming from the wide-angle end state W to the telephoto end state T The first lens group G1 and the second lens group G2 move along the optical axis so that the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 is fixed. Has been configured.

  The first lens group G1 has, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. The lens surface on the image plane I side of the negative meniscus lens L11 is an aspherical surface.

  The second lens group G2 includes, in order from the object side along the optical axis, a biconvex positive lens L21, a biconvex positive lens L22, a biconcave negative lens L23, and a concave surface facing the object side. The positive meniscus third positive lens L24 is joined, and the biconvex positive lens L22 and the biconcave negative lens L23 are cemented, and the surface on the image plane I side of the biconvex positive lens L21 is It is composed of an aspherical surface.

  The third lens group G3 comprises only one biconvex positive lens L31, and the object side surface of the biconvex positive lens L31 is an aspherical surface.

  Focusing from an object at infinity to an object at finite distance is performed by moving the third lens group G3 along the optical axis.

  The aperture stop S is disposed closer to the object side than the biconvex positive lens L21 closest to the object side of the second lens group G2, and the second lens group upon zooming from the wide-angle end state W to the telephoto end state T. Moves together with G2.

  The filter group FL disposed between the third lens group G3 and the image plane I is composed of a low-pass filter, an infrared cut filter, and the like.

  Table 5 below shows values of specifications of the zoom lens according to the fifth example.

(Table 5)
[Overall specifications]
f = 6.077-20.485
FNO = 2.80 ～ 5.41
2ω = 77.4 ° -25.2 °
Ymax = 4.551

[Lens specifications]
rd ν n
1) 32.7889 1.6000 42.71 1.820800
* 2) 6.7418 3.7000
3) 139.1081 1.1000 91.20 1.456000
4) 20.8409 0.5500
5) 13.0108 2.1000 23.78 1.846660
6) 29.4187 (d6)

7) ∞ 0.4000 Aperture stop S
8) 9.5001 1.9000 9.44 1.583130
* 9) -38.1534 0.1000
10) 8.5898 2.8500 52.29 1.755000
11) -28.2172 1.3500 31.31 1.903660
12) 5.3775 1.0000
13) -70.2923 1.5000 91.20 1.456000
14) -11.2815 (d14)

* 15) 36.0000 2.0000 82.56 1.497820
16) -22.9841 (d16)

17) ∞ 2.0000 70.70 1.544400
18) ∞ 0.5000
19) ∞ 0.5000 64.12 1.516800
20) ∞ (Bf)


[Aspherical data]
(Second side)
κ = 0.5996
C4 = -9.59110E-06
C6 = 1.95210E-07
C8 = -1.87890E-08
C10 = 0.00000E + 00

(9th page)
κ = -6.9700
C4 = 1.64570E-04
C6 = 5.44260E-07
C8 = 0.00000E + 00
C10 = 0.00000E + 00

(15th page)
κ = -0.0325
C4 = 9.10230E-06
C6 = 0.00000E + 00
C8 = 0.00000E + 00
C10 = 0.00000E + 00

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 6.07700 11.80000 20.48500
D0 ∞ ∞ ∞
d6 20.16560 8.17788 1.92401
d14 4.69413 10.77848 21.47823
d16 2.60606 2.60606 2.60606

Close-up shooting (shooting distance 300mm)
Wide-angle end state Intermediate focal length state Telephoto end state β -0.02342 -0.04219 -0.07396
D0 246.6925 252.5960 248.1500
d6 20.16560 8.17788 1.92401
d14 4.32363 9.60564 18.21601
d16 2.97656 3.77890 5.86828

[Values for conditional expressions]
(1) Ymax / fw = 0.74889
(2) | f1 | / (fw × ft) ^1/2 = 1.31735
(3) f2 / fw = 2.22972
(4) n23-n24 = 0.44766
(5) ν24−ν23 = 59.89
(6) (Rd + Rc) / (Rd−Rc) = − 0.22067
(7) ν31 = 82.56
(8) fL11 / (f1 × ν12) = 0.00793
(9) (Rb + Ra) / (Rb−Ra) = − 4.32328

  FIGS. 16A to 16C are graphs showing various aberrations when the zoom lens according to Example 5 is in focus at infinity, where FIG. 16A is a wide-angle end state, FIG. 16B is an intermediate focal length state, c) shows aberration diagrams in the telephoto end state. FIGS. 17A to 17C are graphs showing various aberrations when the zoom lens according to Example 5 is in close focus (shooting distance 300 mm). FIG. 17A shows a wide-angle end state, and FIG. Is an intermediate focal length state, and (c) is an aberration diagram in the telephoto end state.

  From each aberration diagram, it can be seen that the zoom lens according to the fifth example has excellent optical performance with various aberrations corrected well in each focal length state from the wide-angle end state W to the telephoto end state T.

(Sixth embodiment)
FIG. 18 is a diagram illustrating a lens configuration of a zoom lens according to Example 6. W represents a wide-angle end state, M represents an intermediate focal length state, and T represents a telephoto end state.

  In FIG. 18, the zoom lens according to the sixth example, in order from the object side along the optical axis, the first lens group G1 having negative refractive power, the aperture stop S, and the second lens having positive refractive power. A lens group G2 and a third lens group G3 having a positive refractive power, and the distance between the first lens group G1 and the second lens group G2 during zooming from the wide-angle end state W to the telephoto end state T The first lens group G1 and the second lens group G2 move along the optical axis so that the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 is fixed. Has been configured.

  The first lens group G1 has, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. The lens surface on the image plane I side of the negative meniscus lens L11 is an aspherical surface.

  The second lens group G2 includes, in order from the object side along the optical axis, a biconvex positive lens L21, a biconvex positive lens L22, a biconcave negative lens L23, and a biconvex positive lens. The biconvex positive lens L22 and the biconcave negative lens L23 are cemented together, and the surface on the image plane I side of the biconvex positive lens L21 is an aspherical surface. .

  The third lens group G3 comprises only one biconvex positive lens L31, and the object side surface of the biconvex positive lens L31 is an aspherical surface.

  Focusing from an object at infinity to an object at finite distance is performed by moving the third lens group G3 along the optical axis.

  The aperture stop S is disposed closer to the object side than the biconvex positive lens L21 closest to the object side of the second lens group G2, and the second lens group upon zooming from the wide-angle end state W to the telephoto end state T. Moves together with G2.

  The filter group FL disposed between the third lens group G3 and the image plane I is composed of a low-pass filter, an infrared cut filter, and the like.

  Table 6 below provides values of specifications of the zoom lens according to the sixth example.

(Table 6)
[Overall specifications]
f = 6.077-20.485
FNO = 2.83-5.56
2ω = 77.5 ° ~ 25.1 °
Ymax = 4.551

[Lens specifications]
rd ν n
1) 39.7667 1.6000 42.71 1.820800
* 2) 6.1456 3.2000
3) 39.7037 1.1000 60.08 1.639999
4) 17.3713 0.3904
5) 12.2844 2.1000 23.78 1.846660
6) 37.3503 (d6)

7) ∞ 0.4000 Aperture stop S
8) 13.5587 1.9000 59.44 1.583130
* 9) -44.1633 0.1000
10) 6.9473 2.7701 54.66 1.729160
11) -132.3917 1.3111 31.31 1.903660
12) 5.2604 1.0000
13) 34.4539 1.5000 91.20 1.456000
14) -15.0830 (d14)

* 15) 16.6818 2.0000 91.20 1.456000
16) -75.6004 (d16)

17) ∞ 2.0000 70.70 1.544400
18) ∞ 0.5000
19) ∞ 0.5000 64.12 1.516800
20) ∞ (Bf)

[Aspherical data]
(Second side)
κ = 0.5432
C4 = -6.07260E-05
C6 = 4.66720E-07
C8 = -4.45010E-08
C10 = 0.00000E + 00

(9th page)
κ = -6.9700
C4 = 6.53420E-05
C6 = 5.61910E-07
C8 = 0.00000E + 00
C10 = 0.00000E + 00

(15th page)
κ = -3.8927
C4 = 1.27970E-04
C6 = 0.00000E + 00
C8 = 0.00000E + 00
C10 = 0.00000E + 00

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 6.07700 11.30000 20.48500
D0 ∞ ∞ ∞
d6 18.60066 7.81137 2.18271
d14 5.47163 12.23325 24.12401
d16 2.05043 2.05043 2.05043

Close-up shooting (shooting distance 300mm)
Wide-angle end state Intermediate focal length state Telephoto end state β -0.02340 -0.04248 -0.07515
D0 248.1228 252.1504 245.8883
d6 18.60066 7.81137 2.18271
d14 5.11910 11.09980 20.89989
d16 2.40297 3.18388 5.27456

[Values for conditional expressions]
(1) Ymax / fw = 0.74889
(2) | f1 | / (fw × ft) ^1/2 = 1.20536
(3) f2 / fw = 2.22996
(4) n23-n24 = 0.44766
(5) ν24−ν23 = 59.89
(6) (Rd + Rc) / (Rd−Rc) = 0.63846
(7) ν31 = 91.20
(8) fL11 / (f1 × ν12) = 0.01120
(9) (Rb + Ra) / (Rb−Ra) = − 5.82982

  FIGS. 19A to 19C are graphs showing various aberrations when the zoom lens according to Example 6 is focused at infinity, where FIG. 19A is a wide-angle end state, FIG. 19B is an intermediate focal length state, c) shows aberration diagrams in the telephoto end state. FIGS. 20A to 20C are graphs showing various aberrations when the zoom lens according to Example 6 is in close focus (shooting distance 300 mm), where FIG. 20A is a wide-angle end state, and FIG. Is an intermediate focal length state, and (c) is an aberration diagram in the telephoto end state.

  From each aberration diagram, it can be seen that the zoom lens according to the sixth example has excellent optical performance with various aberrations corrected well in each focal length state from the wide-angle end state W to the telephoto end state T.

(Seventh embodiment)
FIG. 21 is a diagram illustrating a lens configuration of a zoom lens according to Example 7. W represents a wide-angle end state, M represents an intermediate focal length state, and T represents a telephoto end state.

  In FIG. 21, the zoom lens according to the seventh example, in order from the object side along the optical axis, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens having a positive refractive power. A lens group G2 and a third lens group G3 having a positive refractive power, and the distance between the first lens group G1 and the second lens group G2 during zooming from the wide-angle end state W to the telephoto end state T The first lens group G1 and the second lens group G2 move along the optical axis so that the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 is fixed. Has been configured.

  The first lens group G1 has, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. The lens surface on the image plane I side of the negative meniscus lens L11 is an aspherical surface.

  The second lens group G2 includes, in order from the object side along the optical axis, a biconvex positive lens L21, a biconvex positive lens L22, a biconcave negative lens L23, and a biconvex positive lens. The biconvex positive lens L22 and the biconcave negative lens L23 are cemented together, and the surface on the image plane I side of the biconvex positive lens L21 is an aspherical surface. .

  The third lens group G3 comprises only one biconvex positive lens L31, and the object side surface of the biconvex positive lens L31 is an aspherical surface.

  Focusing from an object at infinity to an object at finite distance is performed by moving the third lens group G3 along the optical axis.

  The aperture stop S is disposed closer to the object side than the biconvex positive lens L21 closest to the object side of the second lens group G2, and the second lens group upon zooming from the wide-angle end state W to the telephoto end state T. Moves together with G2.

  The filter group FL disposed between the third lens group G3 and the image plane I is composed of a low-pass filter, an infrared cut filter, and the like.

  Table 7 below provides values of specifications of the zoom lens according to the seventh example.

(Table 7)
[Overall specifications]
f = 6.077-20.485
FNO = 2.81-5.61
2ω = 77.5 ° -25.2 °
Ymax = 4.551

[Lens specifications]
rd ν n
1) 31.6410 1.5000 40.58 1.864000
* 2) 6.2800 3.4500
3) 930.9800 1.1000 82.56 1.497820
4) 27.2656 0.2000
5) 12.5546 2.0000 23.78 1.846660
6) 31.9616 (d6)

7) ∞ 0.4000 Aperture stop S
* 8) 8.2737 1.8000 49.23 1.768020
9) -64.0328 0.2000
10) 10.3223 2.0000 40.76 1.882997
11) -14.9767 2.1000 28.27 2.003300
12) 4.7699 0.7000
13) 29.4532 1.5000 82.56 1.497820
14) -18.0837 (d14)

* 15) 30.5016 2.1000 82.56 1.497820
16) -23.0185 (d16)

17) ∞ 2.0000 70.70 1.544400
18) ∞ 0.5000
19) ∞ 0.5000 64.12 1.516800
20) ∞ (Bf)

[Aspherical data]
(Second side)
κ = 0.1159
C4 = 2.31300E-04
C6 = 2.01640E-06
C8 = 1.99010E-08
C10 = -7.35730E-11

(8th page)
κ = 0.0133
C4 = 3.15830E-05
C6 = -7.66020E-07
C8 = 2.39110E-08
C10 = 0.00000E + 00

(15th page)
κ = -16.8008
C4 = 9.79570E-05
C6 = 0.00000E + 00
C8 = 0.00000E + 00
C10 = 0.00000E + 00

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 6.07700 11.30000 20.48500
D0 ∞ ∞ ∞
d6 17.27797 7.04061 1.69988
d14 5.19907 10.60224 20.10407
d16 0.88903 0.88903 0.88903

Close-up shooting (shooting distance 300mm)
Wide-angle end state Intermediate focal length state Telephoto end state β -0.02295 -0.04121 -0.07142
D0 252.0682 256.9024 252.7413
d6 17.27797 7.04061 1.69988
d14 4.73531 9.19389 16.45943
d16 1.35279 2.29737 4.53367

[Values for conditional expressions]
(1) Ymax / fw = 0.74889
(2) | f1 | / (fw × ft) ^1/2 = 1.20981
(3) f2 / fw = 1.94175
(4) n23−n24 = 0.50548
(5) ν24−ν23 = 54.29
(6) (Rd + Rc) / (Rd−Rc) = − 0.13982
(7) ν31 = 82.56
(8) fL11 / (f1 × ν12) = 0.00837
(9) (Rb + Ra) / (Rb−Ra) = − 2.70683

  22A to 22C are graphs showing various aberrations when the zoom lens according to Example 7 is in focus at infinity, where FIG. 22A is a wide-angle end state, FIG. 22B is an intermediate focal length state, c) shows aberration diagrams in the telephoto end state. FIGS. 23A to 23C are graphs showing various aberrations when the zoom lens according to Example 7 is in close focus (shooting distance 300 mm), where FIG. 23A is a wide-angle end state, and FIG. Is an intermediate focal length state, and (c) is an aberration diagram in the telephoto end state.

  From each aberration diagram, it can be seen that the zoom lens according to the seventh example has excellent optical performance with various aberrations corrected well in each focal length state from the wide-angle end state W to the telephoto end state T.

(Eighth embodiment)
FIG. 24 is a diagram illustrating a lens configuration of a zoom lens according to Example 8. W represents a wide-angle end state, M represents an intermediate focal length state, and T represents a telephoto end state.

  In FIG. 24, the zoom lens according to the eighth example, in order from the object side along the optical axis, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens having a positive refractive power. A lens group G2 and a third lens group G3 having a positive refractive power, and the distance between the first lens group G1 and the second lens group G2 during zooming from the wide-angle end state W to the telephoto end state T The first lens group G1 and the second lens group G2 move along the optical axis so that the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 is fixed. Has been configured.

  The first lens group G1 includes, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface directed toward the object side, a negative lens L12 having a biconcave shape, and a positive meniscus lens L13 having a convex surface directed toward the object side. The lens surface on the image plane I side of the negative meniscus lens L11 is an aspherical surface.

  The second lens group G2 includes, in order from the object side along the optical axis, a biconvex positive lens L21, a positive meniscus lens L22 having a convex surface facing the object side, and a negative meniscus lens L23 having a convex surface facing the object side. And a positive meniscus positive lens L22 having a convex surface facing the object side and a negative meniscus lens L23 having a convex surface facing the object side are cemented together to form a positive biconvex lens L24. The surface on the image plane I side of the lens L21 is an aspherical surface.

  The third lens group G3 includes only one positive meniscus lens L31 having a convex surface directed toward the object side, and the object side surface of the positive meniscus lens L31 having a convex surface directed toward the object side is formed of an aspherical surface.

  Focusing from an object at infinity to an object at finite distance is performed by moving the third lens group G3 along the optical axis.

  The aperture stop S is disposed closer to the object side than the biconvex positive lens L21 closest to the object side of the second lens group G2, and the second lens group upon zooming from the wide-angle end state W to the telephoto end state T. Moves together with G2.

  The filter group FL disposed between the third lens group G3 and the image plane I is composed of a low-pass filter, an infrared cut filter, and the like.

  Table 8 below provides values of specifications of the zoom lens according to the eighth example.

(Table 8)
[Overall specifications]
f = 6.077-20.485
FNO = 2.86 ～ 5.62
2ω = 77.2 ° to 25.1 °
Ymax = 4.551

[Lens specifications]
rd ν n
1) 30.8750 1.6000 42.71 1.820800
* 2) 6.4359 3.9500
3) -51.7896 1.1000 65.47 1.603000
4) 48.1291 0.3000
5) 16.5037 2.0500 23.78 1.846660
6) 85.4923 (d6)

7) ∞ 0.4000 Aperture stop S
8) 9.1237 1.9000 59.44 1.583130
* 9) -65.5353 0.1000
10) 7.6984 2.9000 54.66 1.729160
11) 33.8982 1.0000 28.27 2.003300
12) 5.1153 1.0000
13) 19.4540 1.5000 70.45 1.487490
14) -26.3289 (d14)

* 15) 14.0000 2.0000 82.56 1.497820
16) 224.1685 (d16)

17) ∞ 2.0000 70.70 1.544400
18) ∞ 0.5000
19) ∞ 0.5000 64.12 1.516800
20) ∞ (Bf)

[Aspherical data]
(Second side)
κ = 0.6414
C4 = -7.50180E-05
C6 = 1.16070E-06
C8 = -6.28330E-08
C10 = 0.00000E + 00

(8th page)
κ = -6.9700
C4 = 1.57450E-04
C6 = 5.50970E-07
C8 = 0.00000E + 00
C10 = 0.00000E + 00

(15th page)
κ = -3.2415
C4 = 1.84720E-04
C6 = 0.00000E + 00
C8 = 0.00000E + 00
C10 = 0.00000E + 00

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 6.07700 11.30000 20.48500
D0 ∞ ∞ ∞
d6 19.39502 7.96363 2.00000
d14 5.68103 12.02388 23.17820
d16 1.71257 1.71257 1.71257

Close-up shooting (shooting distance 300mm)
Wide-angle end state Intermediate focal length state Telephoto end state β -0.02342 -0.04232 -0.07452
D0 247.4520 252.5408 247.3499
d6 19.39502 7.96363 2.00000
d14 5.30889 10.83990 19.86248
d16 2.08471 2.89654 5.02829

[Values for conditional expressions]
(1) Ymax / fw = 0.74889
(2) | f1 | / (fw × ft) ^1/2 = 1.25861
(3) f2 / fw = 2.22314
(4) n23-n24 = 0.51581
(5) ν24−ν23 = 42.18
(6) (Rd + Rc) / (Rd−Rc) = 1.13323
(7) ν31 = 82.56
(8) fL11 / (f1 × ν12) = 0.01110
(9) (Rb + Ra) / (Rb−Ra) = − 2.04370

  FIGS. 25A to 25C are graphs showing various aberrations when the zoom lens according to Example 8 is focused at infinity, in which FIG. 25A is a wide-angle end state, FIG. 25B is an intermediate focal length state, c) shows aberration diagrams in the telephoto end state. FIGS. 26A to 26C are graphs showing various aberrations when the zoom lens according to Example 8 is in close focus (shooting distance 300 mm), where FIG. 26A is a wide-angle end state, and FIG. Is an intermediate focal length state, and (c) is an aberration diagram in the telephoto end state.

  From each aberration diagram, it can be seen that the zoom lens according to the eighth example has excellent optical performance with various aberrations corrected well in each focal length state from the wide-angle end state W to the telephoto end state T.

(Ninth embodiment)
FIG. 27 is a diagram illustrating a lens configuration of a zoom lens according to Example 9, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state.

  In FIG. 27, the zoom lens according to the ninth example includes a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens having a positive refractive power in order from the object side along the optical axis. A lens group G2 and a third lens group G3 having a positive refractive power, and the distance between the first lens group G1 and the second lens group G2 during zooming from the wide-angle end state W to the telephoto end state T The first lens group G1 and the second lens group G2 move along the optical axis so that the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 is fixed. Has been configured.

  The first lens group G1 includes, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface directed toward the object side, a negative lens L12 having a biconcave shape, and a positive meniscus lens L13 having a convex surface directed toward the object side. The lens surface on the image plane I side of the negative meniscus lens L11 is an aspherical surface.

  The second lens group G2 includes, in order from the object side along the optical axis, a biconvex positive lens L21, a biconvex positive lens L22, a biconcave negative lens L23, and a biconvex positive lens. The biconvex positive lens L22 and the biconcave negative lens L23 are cemented together, and the surface on the image plane I side of the biconvex positive lens L21 is an aspherical surface. .

  The third lens group G3 comprises only one biconvex positive lens L31, and the object side surface of the biconvex positive lens L31 is an aspherical surface.

  Focusing from an object at infinity to an object at finite distance is performed by moving the third lens group G3 along the optical axis.

  The aperture stop S is disposed closer to the object side than the biconvex positive lens L21 closest to the object side of the second lens group G2, and the second lens group upon zooming from the wide-angle end state W to the telephoto end state T. Moves together with G2.

  The filter group FL disposed between the third lens group G3 and the image plane I is composed of a low-pass filter, an infrared cut filter, and the like.

  Table 9 below provides values of specifications of the zoom lens according to the ninth example.

(Table 9)
[Overall specifications]
f = 6.077-20.485
FNO = 2.78-5.57
2ω = 77.3 ° -25.1 °
Ymax = 4.551

[Lens specifications]
rd ν n
1) 30.5330 1.5000 40.58 1.864000
* 2) 6.3386 3.6500
3) -103.6850 1.1000 65.44 1.603001
4) 35.2602 0.2000
5) 13.9462 2.0000 23.78 1.846660
6) 50.1594 (d6)

7) ∞ 0.4000 Aperture stop S
* 8) 8.5750 1.9000 49.23 1.768020
9) -51.5904 0.1000
10) 8.6164 2.2000 47.82 1.756998
11) -20.2971 1.8000 28.27 2.003300
12) 4.7758 0.7500
13) 59.0225 1.4500 52.43 1.517417
14) -15.5722 (d14)

* 15) 34.0000 2.1000 82.56 1.497820
16) -21.7725 (d16)

17) ∞ 2.0000 70.70 1.544400
18) ∞ 0.5000
19) ∞ 0.5000 64.12 1.516800
20) ∞ (Bf)

[Aspherical data]
(Second side)
κ = 0.2557
C4 = 1.98980E-06
C6 = 1.18350E-08
C8 = -6.28330E-08
C10 = -7.35730E-11

(8th page)
κ = -0.0032
C4 = 5.02000E-05
C6 = -3.27790E-07
C8 = 2.39110E-08
C10 = 0.00000E + 00

(15th page)
κ = -40.9027
C4 = 9.74630E-05
C6 = -5.21290E-07
C8 = 0.00000E + 00
C10 = 0.00000E + 00

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 6.07700 11.30000 20.48500
D0 ∞ ∞ ∞
d6 17.37860 7.07447 1.69891
d14 5.02990 10.58157 20.34456
d16 0.94574 0.94574 0.94574

Close-up shooting (shooting distance 300mm)
Wide-angle end state Intermediate focal length state Telephoto end state β -0.02301 -0.04137 -0.07186
D0 251.6996 256.4520 252.0646
d6 17.37860 7.07447 1.69891
d14 4.58523 9.21819 16.76704
d16 1.39041 2.30911 4.52325

[Values for conditional expressions]
(1) Ymax / fw = 0.74889
(2) | f1 | / (fw × ft) ^1/2 = 1.20981
(3) f2 / fw = 1.97466
(4) n23-n24 = 0.48588
(5) ν24−ν23 = 24.16
(6) (Rd + Rc) / (Rd−Rc) = − 0.21924
(7) ν31 = 82.56
(8) fL11 / (f1 × ν12) = 0.01079
(9) (Rb + Ra) / (Rb−Ra) = − 2.30864

  28A to 28C are graphs showing various aberrations when the zoom lens according to Example 9 is in focus at infinity, where (a) is a wide-angle end state, (b) is an intermediate focal length state, c) shows aberration diagrams in the telephoto end state. FIGS. 29A to 29C are graphs showing various aberrations when the zoom lens according to Example 9 is in close focus (shooting distance 300 mm), where FIG. 29A is a wide-angle end state, and FIG. Is an intermediate focal length state, and (c) is an aberration diagram in the telephoto end state.

  From the aberration diagrams, it can be seen that the zoom lens according to the ninth example has excellent optical performance with various aberrations corrected well in each focal length state from the wide-angle end state W to the telephoto end state T.

(Tenth embodiment)
FIG. 30 is a diagram illustrating a lens configuration of a zoom lens according to Example 10, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state.

  In FIG. 30, the zoom lens according to the tenth example, in order from the object side along the optical axis, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens having a positive refractive power. A lens group G2 and a third lens group G3 having a positive refractive power, and the distance between the first lens group G1 and the second lens group G2 during zooming from the wide-angle end state W to the telephoto end state T The first lens group G1 and the second lens group G2 move along the optical axis so that the distance between the second lens group G2 and the third lens group G3 increases, and the third lens group G3 is fixed. Has been configured.

  The first lens group G1 has, in order from the object side along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. The lens surface on the image plane I side of the negative meniscus lens L11 is an aspherical surface.

  The second lens group G2 includes, in order from the object side along the optical axis, a biconvex positive lens L21, a biconvex positive lens L22, a biconcave negative lens L23, and a biconvex positive lens. The biconvex positive lens L22 and the biconcave negative lens L23 are cemented together, and the surface on the image plane I side of the biconvex positive lens L21 is an aspherical surface. .

  The third lens group G3 comprises only one biconvex positive lens L31, and the object side surface of the biconvex positive lens L31 is an aspherical surface.

  Focusing from an object at infinity to an object at finite distance is performed by moving the third lens group G3 along the optical axis.

  The aperture stop S is disposed closer to the object side than the biconvex positive lens L21 closest to the object side of the second lens group G2, and the second lens group upon zooming from the wide-angle end state W to the telephoto end state T. Moves together with G2.

  The filter group FL disposed between the third lens group G3 and the image plane I is composed of a low-pass filter, an infrared cut filter, and the like.

  Table 10 below provides values of specifications of the zoom lens according to the tenth example.

(Table 10)
[Overall specifications]
f = 6.077-20.485
FNO = 2.82-5.61
2ω = 77.4 ° ~ 25.1 °
Ymax = 4.551

[Lens specifications]
rd ν n
1) 30.0670 1.5000 40.58 1.864000
* 2) 6.2018 3.4500
3) 930.9800 1.1000 82.56 1.497820
4) 25.5836 0.2000
5) 12.5314 2.0000 23.78 1.846660
6) 33.3850 (d6)

7) ∞ 0.4000 Aperture stop S
* 8) 8.3688 1.8000 49.23 1.768020
9) -83.4993 0.2000
10) 10.3274 2.1000 40.76 1.882997
11) -14.3886 1.9000 28.27 2.003300
12) 4.9016 0.7000
13) 19.2195 1.5000 70.45 1.487490
14) -21.8808 (d14)

* 15) 18.4608 2.1000 82.56 1.497820
16) -45.6758 (d16)

17) ∞ 2.0000 70.70 1.544400
18) ∞ 0.5000
19) ∞ 0.5000 64.12 1.516800
20) ∞ (Bf)

[Aspherical data]
(Second side)
κ = 0.1336
C4 = 2.31300E-04
C6 = 2.01640E-06
C8 = 1.99010E-08
C10 = -7.35730E-11

(8th page)
κ = 0.0133
C4 = 5.09030E-05
C6 = -6.88080E-07
C8 = 2.39110E-08
C10 = 0.00000E + 00

(15th page)
κ = -5.6959
C4 = 1.51740E-04
C6 = 0.00000E + 00
C8 = 0.00000E + 00
C10 = 0.00000E + 00

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 6.07700 11.30000 20.48500
D0 ∞ ∞ ∞
d6 17.35175 7.06596 1.69997
d14 5.70902 11.27059 21.05098
d16 0.49053 0.49053 0.49053

Close-up shooting (shooting distance 300mm)
Wide-angle end state Intermediate focal length state Telephoto end state β -0.02300 -0.04135 -0.07179
D0 251.7119 256.4361 252.0217
d6 17.35175 7.06596 1.69997
d14 5.26802 9.91790 17.50019
d16 0.93153 1.84322 4.04133

[Values for conditional expressions]
(1) Ymax / fw = 0.74889
(2) | f1 | / (fw × ft) ^1/2 = 1.20981
(3) f2 / fw = 1.97466
(4) n23-n24 = 0.51581
(5) ν24−ν23 = 42/18
(6) (Rd + Rc) / (Rd-Rc) = 0.42433
(7) ν31 = 82.56
(8) fL11 / (f1 × ν12) = 0.00836
(9) (Rb + Ra) / (Rb−Ra) = − 2.92027

  FIGS. 31A to 31C are graphs showing various aberrations of the zoom lens according to Example 10 at the time of focusing on infinity, where FIG. 31A is a wide angle end state, FIG. 31B is an intermediate focal length state, c) shows aberration diagrams in the telephoto end state. FIGS. 32A to 32C are graphs showing various aberrations when the zoom lens according to Example 10 is in close focus (shooting distance 300 mm). FIG. 32A shows a wide-angle end state, and FIG. Is an intermediate focal length state, and (c) is an aberration diagram in the telephoto end state.

  From each aberration diagram, it can be seen that the zoom lens according to the tenth example has excellent optical performance with various aberrations corrected well in each focal length state from the wide-angle end state W to the telephoto end state T.

  As described above, according to the zoom lens according to the embodiment, in spite of a simple lens configuration, a wide angle of view exceeding 75 degrees is included in the wide-angle end state, and full-scale wide-angle shooting is possible. At the same time, it is possible to realize a zoom lens having a high zoom ratio of about 3.5 times, an extremely compact zoom lens as a whole, and high optical performance in the entire shooting range from an object at infinity to a close object. it can.

  The contents described below can be appropriately adopted as long as the optical performance is not impaired.

  In the embodiment, the three-group configuration is shown, but the present invention can also be applied to other group configurations such as the fourth group or the fifth group.

  Moreover, it is good also as an in-focus lens group which moves a single lens or a some lens group, or a partial lens evaluation to an optical axis direction, and focuses from an infinite object to a short distance object. The focusing lens group can also be applied to autofocus, and is also suitable for driving a motor for autofocus (such as an ultrasonic motor). In particular, the third lens group is preferably a focusing lens group.

  Alternatively, the lens group or the partial lens group may be vibrated in a direction perpendicular to the optical axis so as to correct an image blur caused by camera shake. In particular, the second lens group is preferably an anti-vibration lens group.

  The lens surface may be an aspherical surface. The aspherical surface may be any of an aspherical surface by grinding, a glass mold aspherical surface in which a glass is formed into an aspherical shape, or a composite aspherical surface in which a resin is formed in an aspherical shape on the glass surface.

  Further, each lens surface is provided with an antireflection film having a high transmittance over a wide wavelength range, and flare and ghost can be reduced to achieve high optical performance with high contrast.

  In addition, in order to explain the present invention in an easy-to-understand manner, the configuration requirements of the embodiment have been described, but it goes without saying that the present invention is not limited to this.

1 shows an electronic still camera equipped with a zoom lens according to an embodiment, where (a) shows a front view and (b) shows a rear view. FIG. 2 shows a cross-sectional view taken along line A-A ′ of FIG. 1 is a diagram illustrating a lens configuration of a zoom lens according to a first example, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state. FIG. 4 is a diagram illustrating various aberrations of the zoom lens according to the first example at the time of focusing on infinity, in which (a) illustrates an aberration diagram in a wide-angle end state, (b) illustrates an intermediate focal length state, and (c) illustrates aberration diagrams in a telephoto end state. Show. FIG. 4A is a diagram illustrating various aberrations of the zoom lens according to the first example when focusing on a close range (shooting distance: 300 mm), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Aberration diagrams in FIG. FIG. 6 is a diagram illustrating a lens configuration of a zoom lens according to Example 2, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state. FIG. 7A is a diagram illustrating various aberrations of the zoom lens according to the second example at the time of focusing on infinity, in which FIG. 9A is an aberration diagram in a wide-angle end state, FIG. Show. FIG. 6 is a diagram illustrating various aberrations of the zoom lens according to Example 2 when focusing on a close range (shooting distance: 300 mm), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Aberration diagrams in FIG. FIG. 10 is a diagram illustrating a lens configuration of a zoom lens according to Example 3, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state. FIG. 9A is a diagram illustrating various aberrations of the zoom lens according to the third example at the time of focusing on infinity, in which FIG. 10A is an aberration diagram in the wide-angle end state, FIG. Show. FIG. 6A is a diagram illustrating various aberrations of the zoom lens according to the third example when focusing on a close range (shooting distance: 300 mm), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Aberration diagrams in FIG. FIG. 10 is a diagram illustrating a lens configuration of a zoom lens according to Example 4, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state. FIG. 9A is a diagram illustrating various aberrations of the zoom lens according to Example 4 at the time of focusing on infinity, in which FIG. 9A is an aberration diagram in the wide-angle end state, FIG. Show. FIG. 6A is a diagram illustrating various aberrations of the zoom lens according to Example 4 when focusing on a close range (shooting distance: 300 mm), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Aberration diagrams in FIG. FIG. 10 is a diagram illustrating a lens configuration of a zoom lens according to Example 5, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state. FIG. 9A is a diagram illustrating various aberrations of the zoom lens according to Example 5 at the time of focusing on infinity, in which FIG. 9A is an aberration diagram in the wide-angle end state, FIG. Show. FIG. 10 is a diagram illustrating various aberrations of the zoom lens according to Example 5 when focusing on a close range (shooting distance: 300 mm), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Aberration diagrams in FIG. FIG. 10 is a diagram illustrating a lens configuration of a zoom lens according to Example 6, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state. FIG. 9A is a diagram illustrating various aberrations of the zoom lens according to Example 6 at the time of focusing on infinity, in which FIG. 10A is an aberration diagram in the wide-angle end state, FIG. Show. FIG. 12 is a diagram illustrating various aberrations of the zoom lens according to Example 6 when focusing on a close range (shooting distance: 300 mm), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Aberration diagrams in FIG. FIG. 10 is a diagram illustrating a lens configuration of a zoom lens according to Example 7, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state. FIG. 10A is a diagram illustrating various aberrations of the zoom lens according to Example 7 when focused at infinity, where FIG. 10A is an aberration diagram at the wide-angle end state, FIG. 10B is an intermediate focal length state, and FIG. Show. FIG. 11 is a diagram illustrating various aberrations of the zoom lens according to Example 7 when focusing on a close range (shooting distance: 300 mm), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Aberration diagrams in FIG. FIG. 10 is a diagram illustrating a lens configuration of a zoom lens according to Example 8, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state. FIG. 10A is a diagram illustrating various aberrations of the zoom lens according to Example 8 at the time of focusing on infinity, in which FIG. 9A is an aberration diagram at a wide angle end state, FIG. 9B is an intermediate focal length state, and FIG. Show. FIG. 10 is a diagram illustrating various aberrations of the zoom lens according to Example 8 when focusing on a close range (shooting distance: 300 mm), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Aberration diagrams in FIG. FIG. 10 is a diagram illustrating a lens configuration of a zoom lens according to Example 9, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state. FIG. 14A is a diagram illustrating various aberrations of the zoom lens according to Example 9 at the time of focusing on infinity, in which FIG. 10A is an aberration diagram at the wide-angle end state, FIG. 9B is an intermediate focal length state, and FIG. Show. FIG. 10 is a diagram illustrating various aberrations of the zoom lens according to Example 9 when focusing on a close range (shooting distance: 300 mm), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Aberration diagrams in FIG. FIG. 14 is a diagram illustrating a lens configuration of a zoom lens according to Example 10, where W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state. FIG. 14A is a diagram illustrating various aberrations of the zoom lens according to Example 10 at the time of focusing on infinity, in which FIG. 10A is an aberration diagram in the wide-angle end state, FIG. 10B is an intermediate focal length state, and FIG. Show. FIG. 11A is a diagram illustrating various aberrations of the zoom lens according to Example 10 when focusing on a close range (shooting distance: 300 mm), where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c) is a telephoto end state. Aberration diagrams in FIG.

Explanation of symbols

1 Electronic still camera 2 Imaging lens (zoom lens)
3 LCD Monitor 4 Release Button 5 Auxiliary Light Issuing Unit 6 Wide (W) -Tele (T) Button 7 Function Button C Image Sensor G1 First Lens Group G2 Second Lens Group G3 Third Lens Group FL Filter Group S Aperture I Image plane

Claims (11)

A first lens group having a negative refractive power, an aperture stop, a second lens group having a positive refractive power, and a third lens group having a positive refractive power in order from the object side along the optical axis. Have
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group is decreased, and the distance between the second lens group and the third lens group is increased. , At least the first lens group and the second lens group move along the optical axis,
The first lens group includes, in order from the object side along the optical axis, a negative meniscus lens having a convex surface directed toward the object side, a negative lens, and a positive lens, and at least one lens surface of the negative lens is Aspheric,
The second lens group includes a first positive lens, a second positive lens, a negative lens, and a third positive lens in order from the object side along the optical axis, and is included in the second lens group. At least one of the lens surfaces is aspheric,
A zoom lens satisfying the following conditions:
0.50 <ft × Ymax / {fw × (fw + ft)} <0.70
1.00 <| f1 | / (fw × ft) ^1/2 <1.40
1.80 <f2 / fw <2.45
However,
Ymax: the maximum image height of the zoom lens,
fw: focal length of the entire zoom lens system in the wide-angle end state;
ft: focal length of the entire zoom lens system in the telephoto end state
f1: the focal length of the first lens group,
f2: focal length of the second lens group. The zoom lens according to claim 1, wherein the following condition is satisfied.
0.35 <n23-n24 <0.65
However,
n23: the refractive index of the negative lens material of the second lens group with respect to the d-line (λ = 587.6 nm);
n24: Refractive index with respect to d-line (λ = 587.6 nm) of the material of the third positive lens of the second lens group. The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
47.0 <ν24−ν23 <75.0
However,
ν23: Abbe number for the d-line (λ = 587.6 nm) of the material of the negative lens of the second lens group,
ν24: Abbe number with respect to the d-line (λ = 587.6 nm) of the material of the third positive lens of the second lens group.   4. The zoom lens according to claim 1, wherein focusing from an object at infinity to an object at a finite distance is performed by moving the third lens group along an optical axis. 5. The third lens group includes one positive lens,
At least one of the lens surfaces of the positive lens of the third lens group is an aspheric surface,
The zoom lens according to claim 1, wherein the following condition is satisfied.
−0.40 <(Rb + Ra) / (Rb−Ra) <1.35
However,
Ra: radius of curvature of the object side surface of the positive lens of the third lens group,
Rb: radius of curvature of the image side surface of the positive lens of the third lens group. The zoom lens according to claim 1, wherein the following condition is satisfied.
71.0 <ν31 <95.0
However,
ν31: Abbe number with respect to d-line (λ = 587.6 nm) of the material of the positive lens of the third lens group. The zoom lens according to claim 1, wherein the following condition is satisfied.
0.0060 <fL11 / (f1 × ν12) <0.0130
However,
fL11: focal length of the negative meniscus lens of the first lens group ν12: Abbe number with respect to d-line (λ = 587.6 nm) of the material of the negative lens of the first lens group. The zoom lens according to any one of claims 1 to 7, wherein the following condition is satisfied.
−7.0 <(Rd + Rc) / (Rd−Rc) <− 1.0
However,
Rc: radius of curvature of the image side surface of the negative lens of the first lens group,
Rd: radius of curvature of the object side surface of the positive lens of the first lens group.   9. The zoom lens according to claim 1, wherein the third lens group is fixed during zooming from the wide-angle end state to the telephoto end state.   An optical apparatus comprising the zoom lens according to claim 1. A first lens group having a negative refractive power, an aperture stop, a second lens group having a positive refractive power, and a third lens group having a positive refractive power in order from the object side along the optical axis. Have
The first lens group includes, in order from the object side along the optical axis, a negative meniscus lens having a convex surface directed toward the object side, a negative lens, and a positive lens, and at least one lens surface of the negative lens is Aspheric,
The second lens group includes a first positive lens, a second positive lens, a negative lens, and a third positive lens in order from the object side along the optical axis, and is included in the second lens group. At least one of the lens surfaces is aspheric,
The following conditions are satisfied,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group is decreased, and the distance between the second lens group and the third lens group is increased. A zooming method characterized by moving at least the first lens group and the second lens group along an optical axis.
0.50 <ft × Ymax / {fw × (fw + ft)} <0.70
1.00 <| f1 | / (fw × ft) ^1/2 <1.40
1.80 <f2 / fw <2.45
However,
Ymax: the maximum image height of the zoom lens,
fw: focal length of the entire zoom lens system in the wide-angle end state;
ft: focal length of the entire zoom lens system in the telephoto end state,
f1: the focal length of the first lens group,
f2: focal length of the second lens group.

Images