JP6076513B2 - Zoom lens and image pickup apparatus including the same - Google Patents

Description

  The present invention relates to a zoom lens that easily secures a zoom ratio and a wide-angle end angle of view. In addition, the present invention relates to an image pickup apparatus including such a zoom lens.

Conventionally, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power are provided. Zoom lenses that perform zooming by changing the distance between the lens groups are known. (Patent Documents 1 and 2)
This type of zoom lens is advantageous in achieving a high zoom ratio because it performs a multiplication action in both the second lens group and the third lens group.

JP 2007-212537 A JP-A-8-179214

  However, as a recent demand for zoom lenses, there is a demand for improved portability by widening the angle of view at the wide-angle end and miniaturization while ensuring a high zoom ratio.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a zoom lens that is advantageous in improving portability by widening the angle of view and reducing the size at the wide angle end while ensuring a high zoom ratio.

  Furthermore, it aims at providing the imaging device provided with such a zoom lens.

  In order to solve the above-described problems, the zoom lens or the imaging apparatus of the present invention is any of the following.

The zoom lens according to the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power in order from the object side to the image side. And a fourth lens group having a positive refractive power, and when zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, and the second lens group and the second lens group The distance between the three lens groups decreases, and the distance between the third lens group and the fourth lens group changes.
The following conditional expression (1) is satisfied.
0.25 <| f12W | / f4 <0.34 (1)
However,
f12W is the focal length of the combined system of the first lens group and the second lens group at the wide-angle end,
f4 is the focal length of the fourth lens group.
Further, the following conditional expressions (3-1) and (10-1) are satisfied.
0.413 ≦ f3 / f4 <0.42 (3-1)
1.306 ≦ f1 / f4 <1.4 (10-1)
However,
f3 is a focal length of the third lens group,
f1 is the focal length of the first lens group,
It is.

By adopting the above-described configuration, it becomes easy to share the zooming burden in the second lens group and the zooming burden in the third lens group, which is advantageous in securing the zooming ratio.
Conditional expression (1) specifies a preferable combined focal length of the first lens group and the second lens group at the wide angle end with respect to the focal length of the fourth lens group.
Ensuring the negative refractive power of the composite system of the first and second lens units at the wide-angle end so as not to exceed the upper limit is advantageous for securing the field angle at the wide-angle end and shortening the total length. In addition, it is easy to suppress the amount of movement of the lens group that moves for zooming, leading to a reduction in size when the lens is retracted.
By appropriately suppressing the refractive power of the synthesis system so as not to fall below the lower limit, it is advantageous for reducing distortion on the wide angle side.

  In the case where the zoom lens has a focusing function, the above-described configuration is a configuration in a state where the farthest distance is in focus. The same applies to each configuration described below.

  In the above-described invention, it is more preferable that one or more of the following matters are satisfied simultaneously.

It is preferable that the following conditional expression (2) is satisfied.
0.2 <| f2 | / f4 <0.25 (2)
However,
f2 is the focal length of the second lens group,
It is.

Conditional expression (2) specifies a preferable focal length of the second lens group with respect to the focal length of the fourth lens group.
Ensuring negative refractive power so as not to exceed the upper limit is advantageous in shortening the overall length of the zoom lens at the wide angle end. In addition, it is easy to suppress the amount of movement of the lens group that moves for zooming, leading to a reduction in size when the lens is retracted.
By appropriately suppressing the negative refractive power so as not to fall below the lower limit, it is advantageous for reducing distortion on the wide angle side.

It is preferable that the following conditional expression (3) is satisfied.
0.35 <f3 / f4 <0.45 (3)
However,
f3 is the focal length of the third lens group.

Conditional expression (3) specifies a preferable focal length of the third lens group with respect to the fourth lens group.
By securing the positive refractive power of the third lens group so as not to exceed the upper limit, it becomes easy to suppress the amount of movement of the lens group that moves for zooming, which leads to downsizing of the zoom lens when retracted.
It is advantageous for reducing spherical aberration and the like by appropriately suppressing the positive refractive power so as not to fall below the lower limit.

It is preferable that the following conditional expression (4) is satisfied.
4 <f4 / fw <5 (4)
However,
f4 is the focal length of the fourth lens group,
fw is the focal length of the entire zoom lens system at the wide angle end.

Conditional expression (4) specifies a preferable refractive power of the fourth lens group.
By ensuring the positive refractive power of the fourth lens group so as not to exceed the upper limit, it is possible to sufficiently ensure the function of moving the exit pupil away from the image plane, leading to an improvement in image quality.
It is easy to suppress curvature of field by appropriately suppressing the positive refractive power so as not to fall below the lower limit.

  It is preferable that the fourth lens group moves in the optical axis direction during focusing.

  When the fourth lens group satisfies the above-described conditional expression (4), the amount of change in the image plane position relative to the amount of movement of the fourth lens group during focusing can be made appropriate, which is advantageous for focusing control.

  It is preferable that the third lens group includes a lens having an aspherical surface in which the positive refractive power decreases as the distance from the optical axis increases.

The third lens group is a lens group in which positive refractive power tends to be strong and spherical aberration tends to occur.
Providing an aspheric surface having the above-described shape is advantageous in reducing spherical aberration.

  It is preferable to have an aspherical lens having an aspherical shape in which the negative refractive power becomes weaker as the second lens group moves away from the optical axis.

The second lens group is a lens group in which negative refractive power tends to be strong as the optical system is miniaturized, and field curvature on the wide-angle side is likely to occur.
Providing the aspherical surface having the above-described shape is advantageous in reducing field curvature on the wide-angle side.
In addition, spherical aberration in the positive direction near the telephoto end, which is likely to occur when the refractive power of the second lens group is increased, can be easily reduced.

  Further, the aspheric lens is more preferably a double-sided aspheric lens.

  A sufficient degree of freedom in aberration reduction and edge spacing can be secured, which is advantageous for higher performance.

More preferably, the aspheric lens is a negative lens that satisfies the following conditional expression (A).
ASP1−ASP2> 0 (A)
However,
ASP1 is the amount of aspherical deviation at the principal ray passage position that reaches the maximum image height on the object side surface of the aspherical lens at the wide-angle end,
ASP2 is an aspherical deviation amount at the passing position of the principal ray reaching the maximum image height on the image side surface of the aspherical lens at the wide angle end.

Conditional expression (A) specifies a preferable aspherical shape when the aspherical lens is a negative lens.
This is a conditional expression for reducing the refractive power of the negative lens from the vicinity of the optical axis to the outside of the axis by an aspherical action. Satisfying the aspherical conditional expression (A) is advantageous for reducing the field curvature at the wide-angle end and the spherical aberration at the telephoto end.
The amount of aspherical deviation is a difference measured in the optical axis direction with respect to a reference spherical surface having the same position as the top of the corresponding aspheric surface and the paraxial radius of curvature of the aspheric surface as the curvature radius. The deviation to the image side is a plus sign.

  The first lens group includes, in order from the object side, a cemented lens including a negative meniscus lens having a convex surface facing the object side, a positive meniscus lens having a convex surface facing the object side, and a positive meniscus lens having a convex surface facing the object side. It is preferable.

  It becomes easy to correct spherical aberration, coma and the like in the first lens group.

  It is preferable that the second lens group includes, in order from the object side, a negative meniscus lens having a convex surface directed toward the object side, a biconcave negative lens, and a positive lens.

  This is advantageous in achieving both a reduction in size and optical performance while sufficiently securing the negative refractive power in the second lens group. Furthermore, it is preferable that the biconcave negative lens is the aforementioned aspherical lens.

  The third lens group includes, in order from the object side, a cemented lens including a positive meniscus lens having a convex surface facing the object side, a negative meniscus lens having a convex surface facing the object side, and a positive lens having a convex surface facing the object side. Is preferred.

  In the third lens group, a positive lens on the object side is formed of a meniscus lens, and the object side of the cemented lens is a convex surface, whereby the principal point of the third lens group can be arranged on the object side. This is advantageous in securing a zooming function, reducing curvature of field, and coma.

Furthermore, it is preferable that the third lens group satisfies the following conditional expression (B).
−1.5 <(Rc + R3img) / (Rc−R3img) <− 1 (B)
However,
Rc is the paraxial radius of curvature of the cemented surface of the cemented lens in the third lens group,
R3img is the paraxial radius of curvature of the most image-side refractive surface in the third lens group.

By making it not fall below the lower limit of conditional expression (B), it is possible to suppress excess of the refractive power of the cemented surface, and to easily suppress deterioration in optical performance due to decentering of the cemented lens and the entire third lens group during assembly.
By making sure that the upper limit of conditional expression (B) is not exceeded, it becomes easy to obtain sufficient refractive power at the cemented surface to reduce chromatic aberration and curvature of field.

  The fourth lens group is preferably composed of one positive lens.

  It is possible to secure the function of keeping the exit pupil away from the fourth lens while reducing the cost.

  Upon zooming from the wide-angle end to the telephoto end, the first lens unit moves so as to be positioned on the object side at the telephoto end with respect to the position at the wide-angle end, and the second lens unit moves to the object side after the image. The third lens group moves to the object side at the telephoto end with respect to the position at the wide angle end, and the fourth lens group moves to the image side after moving to the image side. It is preferable to move including a locus that moves to the image side and then moves to the image side.

This is advantageous for correcting fluctuations in field curvature from the intermediate state to the telephoto end in zooming.
In addition, it is easy to suppress sudden fluctuations in F number (decrease in brightness) in an intermediate state during zooming.

It is preferable that the third lens group satisfies the following conditional expression (5).
0.1 <d3A / Σd3 <0.3 (5)
However,
d3A is the maximum value of the axial spatial distance in the third lens group,
Σd3 is the thickness of the third lens group on the optical axis.

Conditional expression (5) is a preferable conditional expression for reducing the size of the third lens unit.
By ensuring the air separation distance so that it does not fall below the lower limit, the air conversion length can be increased compared to the case where it is filled with a medium, realizing miniaturization and reducing the effect on the aberration of the air lens between both lenses. By doing so, it is possible to reduce performance degradation due to eccentricity and gaps in the interval.
By not exceeding the upper limit, the thickness of the lens can be ensured while suppressing an increase in size in the direction of the third lens group optical axis, leading to securing the productivity of components.

More preferably, the cemented surface of the cemented lens in the third lens group satisfies the following conditional expressions (6) and (C).
0.07 <Rc / ft <0.1 (6)
−35 <ν32−ν33 <−25 (C)
However,
Rc is the radius of curvature of the cemented surface of the cemented lens in the third lens group,
ft is the focal length of the entire zoom lens system at the telephoto end ν32 is the Abbe number of the negative meniscus lens in the cemented lens in the third lens group ν33 is the Abbe number of the positive lens in the cemented lens in the third lens group .

Conditional expression (6) is a preferable conditional expression in order to favor both the correction of axial chromatic aberration and coma aberration.
By making it not fall below the lower limit, it is possible to easily process the two lenses constituting the cemented surface.
By not exceeding the upper limit, it becomes advantageous for correction of axial chromatic aberration and coma at the telephoto end.
Conditional expression (C) is a preferable conditional expression for satisfactorily correcting axial chromatic aberration during zooming.
By making it not below the lower limit, the axial chromatic aberration at the telephoto end can be corrected satisfactorily.
By preventing the upper limit from being exceeded, axial chromatic aberration in the intermediate state can be favorably corrected.

It is preferable that the second lens group satisfies the following conditional expression (7).
0.8 <R1img / R2obj <1.2 (7)
0.05 <D12 / IH <0.15 (D)
However,
R1img is the radius of curvature of the most image-side refractive surface of the first lens group,
R2obj is the radius of curvature of the most object-side refractive surface of the second lens group,
D12 is the air spacing on the optical axis of the first lens group and the second lens group at the wide-angle end,
IH is the image height on the imaging surface by the zoom lens.

By satisfying conditional expression (7), the first lens group and the second lens group can be brought closer to each other at the wide angle end by bringing the curvatures of the refractive surfaces of both the first lens group and the second lens group facing each other closer to each other. It is easy to reduce the height of light in the group, which is advantageous for downsizing.
It is preferable in terms of miniaturization to keep the second lens group closer to the first lens group at the wide-angle end so as not to fall below the lower limit value and to suppress the effective diameter of the first lens so as not to exceed the upper limit value. .
By making sure that the lower limit of conditional expression (D) is not exceeded, it is possible to prevent the distance between the first lens group and the second lens group from becoming too close, and to prevent the respective lens groups from colliding due to manufacturing variation or deformation due to impact. Space can be secured.
By not exceeding the upper limit value, the height of the light beam can be made closer between the exit surface of the first lens group and the entrance surface of the second lens group, which is advantageous for reducing the effective diameter of the first lens group.

It is preferable to satisfy conditional expression (E).
6.5 <ft / fw <20.0 (E)
However,
ft is the focal length of the entire zoom lens system at the wide-angle end,
fw is the focal length of the entire zoom lens system at the wide angle end.
The zoom lens described above is configured to ensure a zoom ratio. Therefore, it is preferable to ensure a zoom ratio so as not to fall below the lower limit.
The amount of movement of each lens group can be reduced while suppressing the refractive power of each lens group so as not to exceed the upper limit, which is advantageous in reducing the size of the lens barrel when retracted.

It is preferable to dispose a light amount reducing member made of polyolefin, which can be inserted and retracted in the optical path of the zoom lens.
By using a material having a small retardation effect of the light amount reducing member, resolution deterioration due to birefringence can be prevented.

It is preferable that the zoom lens can be retracted and the third lens group is stored while being moved eccentrically with respect to the optical axis of the other lens when retracted.
This is advantageous for further downsizing when retracted.

Further, as a recent demand for zoom lenses, improvement in portability is required by downsizing when retracted.
The present invention of the second aspect is to provide an imaging apparatus having a zoom lens, which is advantageous for downsizing the zoom lens and is advantageous for improving portability.

An imaging apparatus according to a second aspect of the present invention includes a plurality of lens groups, a zoom lens that performs zooming by changing the distance between the lens groups, and receives an image from the zoom lens and converts it into an electrical signal. And an imaging device having an imaging surface.
The zoom lens can be retracted when not in use, and at least two lenses in the zoom lens satisfy the following conditional expression (8).
0.01 <d / IH <0.1 (8)
However,
d is the thickness of each of the at least two lenses on the optical axis;
IH is the image height on the imaging surface by the zoom lens.

By reducing the thickness on the axis of the lens so as not to exceed the upper limit of conditional expression (8), it is possible to reduce the size when retracting.
In order to ensure the rigidity of the lens, it is preferable to ensure the thickness on the lens axis so as not to fall below the lower limit.
By using a plurality of such lenses, it is advantageous for downsizing when retracted, and the portability of the imaging device is improved.

  Furthermore, it is preferable that any two of the at least two lenses satisfying the conditional expression (8) are negative lenses.

  Since the thickness on the optical axis is thin, it is advantageous for both the reduction of the thickness of the lens and the securing of negative refractive power.

  Furthermore, it is more preferable that the two negative lenses are included in the same lens group A among the plurality of lens groups in the zoom lens, and the positive lens is arranged in the same lens group A.

  By including a plurality of negative lenses and at least one positive lens in the same lens group A, it is advantageous for reducing the size of the lens group and ensuring optical performance.

  The same lens group A is preferably a lens group having a negative refractive power.

  By using the same lens group A as a lens group with negative refractive power, the advantage of miniaturization and securing negative refractive power by using a plurality of negative lenses with small axial thicknesses leads to miniaturization and high performance. .

Of the two negative lenses in the same lens group A, one is the first negative lens and the other is the second negative lens,
It is preferable that the following conditional expression (9) is satisfied.
1.7 <(ndLN1 + ndLN2 + ndLP1) / 3 <2.2 (9)
However,
ndLN1 is the refractive index of the first negative lens in the same lens group A at the d-line,
ndLN2 is the refractive index of the second negative lens in the same lens group A at the d-line,
ndLP1 is the refractive index at the d-line of the positive lens in the same lens group A.

Increasing the average value of the refractive index of each lens so as not to fall below the lower limit value of conditional expression (9) is advantageous in reducing aberrations.
By not exceeding the upper limit, it is advantageous in reducing the cost of the lens material, improving the workability, and reducing higher-order chromatic aberration.

  It is preferable that a lens unit B having positive refractive power is disposed on the image side of the same lens unit A.

  It becomes easy to give the lens unit B having positive refractive power a zooming function.

  Furthermore, it is more preferable that the lens unit C having positive refractive power is disposed on the object side of the same lens unit A.

  It becomes easy to provide a zooming function of the same lens group A having negative refractive power.

Further, a positive refractive power lens group D is further provided on the image side of the positive refractive power lens group B, the positive refractive power lens group C is the first lens group, and the same lens group A is the second lens group. When the first positive refractive power lens group B is the third lens group and the positive refractive power lens group D is the fourth lens group, the first lens group and the second lens group in this order from the object side. More preferably, the third lens group and the fourth lens group are arranged in this order, and the following conditional expressions (1) and (2) are satisfied.
0.25 <| f12W | / f4 <0.34 (1)
0.2 <| f2 | / f4 <0.25 (2)
However,
f12W is the focal length of the combined system of the first lens group and the second lens group at the wide-angle end,
f2 is the focal length of the second lens group,
f4 is the focal length of the fourth lens group,
It is.

  The technical significance of conditional expressions (1) and (2) is as described above.

In addition, it is more preferable that any of the zoom lenses described above satisfies the following conditional expression (10).
1.2 <f1 / f4 <1.4 (10)
However,
f1 is the focal length of the first lens group,
f4 is the focal length of the fourth lens group.

By securing the refractive power of the first lens group so as not to exceed the upper limit of conditional expression (10), it becomes easy to secure the zooming function in the second lens group, and the total length at the telephoto end is reduced and associated with it. This leads to downsizing when retracted.
By suppressing the refractive power of the first lens group so as not to fall below the lower limit, aberrations in the first lens group are reduced.

It is preferable to use any of the zoom lenses described above in an image pickup apparatus having a zoom lens and an image pickup element having an image pickup surface arranged on the image side thereof.
Since the zoom lens described above has good telecentricity, the influence of oblique incidence of light on the imaging surface can be suppressed, and a high-quality image can be obtained.
As for the above-mentioned composition, it is more preferred to satisfy a plurality simultaneously mutually.
For example, any of the above-described zoom lenses may be used in any of the above-described imaging devices.

Even if each conditional expression is satisfied individually, each effect is easily obtained, which is preferable.
Further, for each conditional expression, it is preferable to change the lower limit value or the upper limit value as follows because the effect can be further ensured.

In conditional expression (1), it is more preferable to set the lower limit value to 0.3, and further to 0.31.
More preferably, the upper limit value is 0.32.

More preferably, the lower limit value of conditional expression (2) is 0.22.
More preferably, the upper limit value is 0.24, more preferably 0.23.

For conditional expression (3), it is more preferable to set the lower limit value to 0.38, more preferably 0.39.
The upper limit value is more preferably 0.42, and further preferably 0.41.

In conditional expression (4), it is more preferable to set the lower limit to 4.3, and even 4.5.
More preferably, the upper limit value is 4.6.

In conditional expression (5), it is more preferable to set the lower limit value to 0.2, more preferably 0.25.
More preferably, the upper limit value is 0.29, more preferably 0.26.

For conditional expression (6), it is more preferable to let the lower limit value to be 0.08.

In conditional expression (7), it is more preferable to set the lower limit to 0.9.
More preferably, the upper limit value is 1.1.

In conditional expression (8), it is more preferable that the lower limit value be 0.05.

In conditional expression (9), it is more preferable to let the lower limit value to be 1.8.
More preferably, the upper limit value is 2.0.

For conditional expression (10), it is more preferable to let the lower limit value to be 1.25.
More preferably, the upper limit is 1.35.

For conditional expression (A), it is more preferable to set the lower limit value to 0.001, and further to 0.002.
On the other hand, in order to facilitate the processing of the surface shape, it is preferable to set an upper limit value of 0.2 so as not to exceed this.
Conditional expression (B)
More preferably, the lower limit is −1.4, more preferably −1.35, and even more preferably −1.3.
More preferably, the upper limit value is set to -1.03.
Conditional expression (C)
More preferably, the lower limit is -33.
More preferably, the upper limit value is −30.
Conditional expression (D)
The lower limit is more preferably 0.07.
More preferably, the upper limit value is 0.10, more preferably 0.08.
Conditional expression (E)
More preferably, the lower limit value is 7.0, more preferably 7.5.
More preferably, the upper limit value is 14.0, more preferably 9.0.

According to the present invention, it is possible to provide a zoom lens that is advantageous for improving portability by widening the angle of view at the wide-angle end and reducing the size even when a high zoom ratio is ensured.
Furthermore, an imaging device including such a zoom lens can be provided.

FIG. 3 is a lens cross-sectional view at the wide-angle end (a) and the telephoto end (b) when focusing on an object point at infinity according to Example 1 of the zoom lens of the present invention. It is the same figure as FIG. 1 of Example 2 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 3 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 4 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 5 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 6 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 7 of the zoom lens of this invention. It is a figure similar to FIG. 1 of Example 8 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 9 of the zoom lens of this invention. It is a figure similar to FIG. 1 of Example 10 of the zoom lens of this invention. FIG. 6 is an aberration diagram for Example 1 upon focusing on an infinite distance. FIG. 6 is an aberration diagram for Example 2 upon focusing on an infinite distance. FIG. 10 is an aberration diagram for Example 3 upon focusing on an infinite distance. FIG. 10 is an aberration diagram for Example 4 upon focusing on an infinite distance. FIG. 10 is an aberration diagram for Example 5 upon focusing on an infinite distance. FIG. 10 is an aberration diagram for Example 6 upon focusing on an infinite distance. FIG. 10 is an aberration diagram for Example 7 upon focusing on an infinite distance. FIG. 10 is an aberration diagram for Example 8 upon focusing on an infinite distance. FIG. 10 is an aberration diagram for Example 9 upon focusing on an infinite distance. FIG. 10 is an aberration diagram for Example 10 upon focusing on an infinite distance. It is a schematic sectional drawing of the camera using the zoom lens of this invention.

  A zoom lens and an image pickup apparatus including the zoom lens according to the embodiment will be described below.

  In any of the embodiments, by providing the above-described device, a four-unit zoom lens having a wide wide-angle end angle of view, a small size while ensuring a zoom ratio, and good optical performance is provided.

  In addition, the zoom lens of each embodiment has a wide wide-angle end angle of view, a small zooming ratio, and excellent optical performance when used as a photographing lens for a compact digital camera or an interchangeable lens digital camera. A digital camera can be configured.

Each example shown below (Examples 2 to 7 are reference examples) is an example of a zoom lens of an interchangeable lens or lens-integrated digital camera and an image pickup apparatus including the same. In Examples 1 to 10, the zoom lens has high optical performance and is excellent in compactness.

  Examples 1 to 10 of the zoom lens according to the present invention will be described below. FIGS. 1 to 10 show lens cross-sectional views of Examples 1 to 10 at (a) a wide-angle end when focusing on an object point at infinity and (b) a telephoto end, respectively.

  In each figure, the first lens group is G1, the second lens group is G2, the aperture stop is S, the third lens group is G3, the fourth lens group is G4, and a CCD (or CMOS, etc.) is imaged as an image sensor. The face is indicated by I. The aperture stop has an opening with a variable opening size, and the F number can be changed. (The F number in the numerical example described later indicates the minimum F number within a changeable range.) The cover glass of the CCD is omitted in FIGS. 1 to 10 and numerical data described later, and will be described in FIG. 21 described later. To illustrate. A low-pass filter or an infrared light absorption filter may be arranged in the back focus.

In each embodiment, the aperture stop S is disposed immediately before the object side of the third lens group G3, and moves together with the third lens group G3 during zooming. The center of gravity of the aperture of the aperture stop S is located in the medium of the third lens group G3. That is, the object side surface of the third lens group G3 is a convex surface that enters the aperture of the aperture stop.
A mechanical shutter with a variable opening area (not shown) in front of the aperture stop S or in the space in the third lens group G3, an ND filter made of a detachable polyolefin material shown in the description of FIG. It is good also as a structure which arranges and adjusts light quantity.

The lens configuration of each example will be described.
The first lens group G1, in order from the object side, is a cemented lens in which a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side are cemented, and a positive meniscus lens having a convex surface facing the object side And a total of three lenses.
The second lens group G2 includes, in order from the object side, a negative meniscus lens having a convex surface directed toward the object side, a biconcave negative lens, and a biconvex positive lens, and is composed of a total of three single lenses.
The third lens group G3 is composed of a cemented lens in which a positive meniscus lens having a convex surface facing the object side, a negative meniscus lens having a convex surface facing the object side, and a positive meniscus lens having a convex surface facing the object side are cemented. It consists of a total of three lenses.
The fourth lens group G4 is composed of a biconvex positive lens, and is composed of one lens in total.

Next, the position of the aspheric surface in each embodiment will be described.
The biconcave negative lens in the second lens group G2 is aspheric on both sides in each example.
The single lens of the positive meniscus lens in the third lens group G3 has an aspheric object side surface.
Among them, the single lens of the positive meniscus lens in the third lens group in Examples 4, 5, and 6 has both aspheric surfaces.
In addition, the image side surface of the cemented lens in the third lens group G3 is aspheric in each example.
The biconvex positive lens in the fourth lens group G4 is an aspheric lens.
Among them, in Example 8, only the image side surface is aspherical, and in other examples, both surfaces are aspherical.
Of course, the present invention need not be limited to these aspherical arrangements.

Next, the moving system from the wide-angle end to the telephoto end of each embodiment will be shown.
The first lens group G1 is common to all the examples and always moves to the object side.
The second lens group G2 is common to all the embodiments, and first moves to the object side, and then moves to the image side by reversing the moving direction. The second lens group G2 is positioned closer to the object side at the telephoto end than at the wide angle end.
The third lens group G3 has a different movement method depending on the embodiment.
In Embodiments 1 to 6 and 8, the lens always moves to the object side from the wide-angle end to the telephoto end.
In the seventh, ninth, and tenth embodiments, first, the object moves to the object side, and then the moving direction is reversed to move to the image side. The third lens group G3 is located closer to the object side at the telephoto end than at the wide angle end.
The fourth lens group G4 is common to all the embodiments, and first moves to the image side, and then moves to the object side by reversing the moving direction. Thereafter, the movement direction is reversed and the image is moved to the image side. The fourth lens group G4 is positioned closer to the image side at the telephoto end than at the wide angle end.
The distance between the first lens group G1 and the second lens group G2 and the distance between the third lens group G3 and the fourth lens group G4 are always enlarged during zooming from the wide angle end to the telephoto end.
The distance between the second lens group G2 and the third lens group G3 is always reduced upon zooming from the wide-angle end to the telephoto end.
Of course, the present invention need not be limited to these movement methods. Various changes are possible. For example, the change in the distance between the third lens group G3 and the fourth lens group G4 may be decreased temporarily during zooming. The first lens group G1 and the second lens group G2 may first be moved to the image side upon zooming from the wide-angle end to the telephoto end.

In each embodiment, the fourth lens group G4 is moved to the object side to perform focusing from an infinite distance to a close distance.
Of course, another lens group (for example, the first lens group G1) may be used as the focusing lens group.
Further, the ghost can be reduced by applying a rectangular black paint to the most image side lens.
In addition, as a filter immediately before the image sensor, a material having a high absorption rate in a specific wavelength region (for example, an infrared region) is used, and a coating having a high reflectance in the specific wavelength region (for example, an infrared region) is applied to the surface of the filter. The hybrid structure also has an advantage in reducing ghosts.
Further, a reflection reducing coat such as a multi coat may be applied to the lens closest to the image side.
Coating the most image side lens with a glass material is advantageous in reducing ghosts.

The numerical data of the lens in each example is shown below.
In the first to tenth embodiments, the image height is 3.88 and a constant rectangular effective imaging area in all zooming ranges from the wide-angle end to the telephoto end. The value corresponding to the conditional expression in each embodiment is a value in a state in which the object point at infinity is in focus.

  In addition to data at the wide-angle end and the telephoto end, the zoom data includes a first intermediate focal length state (referred to as first intermediate) and a second intermediate focal length state (second intermediate) in the zooming range from the wide-angle end to the telephoto end. A third intermediate focal length state (denoted as third) is also shown.

In the numerical data of the lens in each embodiment, r is the radius of curvature of each lens surface, d is the thickness or spacing of each lens, nd is the refractive index at the d-line of each lens, and νd is the Abbe at the d-line of each lens. Number, K is a conical coefficient, A4, A6, A8, and A10 are aspherical coefficients, and e ± N is × 10 ± ^N.
The total lens length is obtained by adding the back focus BF to the distance on the optical axis from the entrance surface to the exit surface of the lens. The back focus BF is indicated by the air conversion length.
Each aspheric shape is expressed by the following expression using each aspheric coefficient in each embodiment.
Z = (Y ² / r) / [1+ {1− (1 + K) · (Y / r) ² } ^1/2 ]
+ A4 × Y ⁴ + A6 × Y ⁶ + A8 × Y ⁸ + A10 × Y ¹⁰
However, the coordinate in the optical axis direction is Z, and the coordinate in the direction perpendicular to the optical axis is Y.

Numerical example 1
Scaling ratio 7.679
Unit mm
Surface data surface number r d nd νd
1 40.923 0.70 1.84666 23.78
2 19.735 2.21 1.72916 54.68
3 220.044 0.10
4 17.858 1.73 1.72916 54.68
5 52.314 Variable
6 52.314 0.30 1.88300 40.76
7 4.976 1.91
8 (Aspherical surface) -15.150 0.30 1.80490 40.81
9 (Aspherical surface) 6.965 0.69
10 9.437 1.31 1.94595 17.98
11 -274.180 Variable
12 (brightness stop) ∞ -0.15
13 (Aspherical) 4.000 1.27 1.69350 53.20
14 24.654 0.98
15 61.322 0.40 1.74077 27.76
16 3.229 1.17 1.58313 59.38
17 (Aspherical) 255.572 Variable
18 (Aspherical) 23.445 1.85 1.53071 55.70
19 (Aspherical surface) -18.092 Variable Image surface (imaging surface) ∞
Aspheric data 8th surface
K = 0.000, A4 = -7.72006e-04, A6 = 4.88018e-05, A8 = -1.10336e-06, A10 = 7.20649e-09
9th page
K = 0.000, A4 = -1.05539e-03, A6 = 4.25808e-05, A8 = 9.79211e-07, A10 = -7.70421e-08
13th page
K = 0.000, A4 = -3.33021e-04, A6 = -9.61234e-06, A8 = 5.00000e-07, A10 = 0.000
17th page
K = 0.000, A4 = 4.28328e-03, A6 = 1.98108e-04, A8 = 6.19852e-05, A10 = 0.000
18th page
K = 0.000, A4 = 4.15946e-04, A6 = 0.000, A8 = 0.000, A10 = 0.000
19th page
K = 0.000, A4 = 4.79494e-04, A6 = -6.51602e-06, A8 = 7.13258e-08, A10 = 0.000
Zoom data
Wide angle end 1st middle 2nd middle 3rd middle Telephoto end Focal length 4.48 7.18 11.70 20.10 34.39
F number 3.38 4.24 5.21 5.85 6.02
Angle of view (2ω) 90.08 58.17 36.73 21.90 12.85
Image height (IH) 3.88 3.88 3.88 3.88 3.88
When focusing at infinity
d5 0.28 2.37 5.30 9.35 13.24
d11 7.85 5.66 4.09 2.40 1.00
d17 3.49 7.94 12.33 14.84 15.66
d19 5.64 4.87 4.22 5.18 4.57
BF 5.64 4.87 4.22 5.18 4.57
Total lens length 32.03 35.63 40.72 46.53 49.25
Zoom lens group data Group Start point Focal length
1 1 26.03
2 6 -4.61
3 13 8.15
4 18 19.54

Numerical example 2
Scaling ratio 7.680
Unit mm
Surface data surface number r d nd νd
1 43.469 0.70 1.84666 23.78
2 20.250 2.17 1.72916 54.68
3 258.510 0.10
4 17.161 1.77 1.72916 54.68
5 48.639 Variable
6 48.639 0.30 1.88300 40.76
7 4.966 1.91
8 (Aspherical surface) -15.373 0.30 1.80490 40.81
9 (Aspherical surface) 6.765 0.71
10 9.258 1.27 1.94595 17.98
11 -915.721 Variable
12 (brightness stop) ∞ -0.15
13 (Aspherical) 4.118 1.40 1.69350 53.20
14 27.373 1.01
15 41.265 0.40 1.74077 27.76
16 3.153 1.14 1.58313 59.38
17 (Aspherical) 405.529 Variable
18 (Aspherical) 30.982 1.85 1.53071 55.70
19 (Aspherical) -16.488 Variable Image surface (imaging surface) ∞
Aspheric data 8th surface
K = 0.000, A4 = -6.77064e-04, A6 = 4.31723e-05, A8 = 4.98034e-07, A10 = -1.18569e-07
9th page
K = 0.000, A4 = -1.01070e-03, A6 = 5.94348e-05, A8 = -2.45658e-07, A10 = -1.10369e-07
13th page
K = 0.000, A4 = -3.81605e-04, A6 = -1.12348e-05, A8 = 5.00000e-07, A10 = 0.000
17th page
K = 0.000, A4 = 3.84313e-03, A6 = 1.92431e-04, A8 = 5.02667e-05, A10 = 0.000
18th page
K = 0.000, A4 = 2.83467e-04, A6 = 0.000, A8 = 0.000, A10 = 0.000
19th page
K = 0.000, A4 = 3.36725e-04, A6 = -7.03093e-06, A8 = 1.00000e-07, A10 = 0.000
Zoom data
Wide angle end 1st middle 2nd middle 3rd middle Telephoto end Focal length 4.48 7.16 11.70 19.90 34.40
F number 3.32 4.19 5.18 5.79 6.02
Angle of view (2ω) 90.20 58.68 36.87 22.14 12.88
Image height (IH) 3.88 3.88 3.88 3.88 3.88
When focusing at infinity
d5 0.28 2.00 4.88 9.01 13.01
d11 7.84 5.49 3.91 2.34 1.00
d17 3.52 7.89 12.41 14.79 15.89
d19 5.54 4.90 4.22 5.18 4.45
BF 5.54 4.90 4.22 5.18 4.45
Total lens length 32.05 35.14 40.29 46.18 49.22
Each group focal length zoom lens group data Group Start point Focal length
1 1 25.93
2 6 -4.54
3 13 8.01
4 18 20.55

Numerical Example 3
Scaling ratio 7.678
Unit mm
Surface data surface number r d nd νd
1 42.791 0.70 1.84666 23.78
2 20.136 2.16 1.72916 54.68
3 249.287 0.10
4 17.511 1.75 1.72916 54.68
5 50.430 Variable
6 50.430 0.30 1.88300 40.76
7 4.966 1.91
8 (Aspherical surface) -15.806 0.30 1.80490 40.81
9 (Aspherical surface) 6.941 0.69
10 9.456 1.27 1.94595 17.98
11 -474.957 Variable
12 (brightness stop) ∞ -0.15
13 (Aspherical) 4.074 1.40 1.69350 53.20
14 24.450 1.01
15 42.784 0.40 1.74077 27.76
16 3.193 1.10 1.58313 59.38
17 (Aspherical) 405.529 Variable
18 (Aspherical surface) 29.109 1.85 1.53071 55.70
19 (Aspherical surface) -16.598 Variable image surface (imaging surface) ∞
Aspheric data 8th surface
K = 0.000, A4 = -8.75357e-04, A6 = 3.88439e-05, A8 = 2.58760e-06, A10 = -2.29541e-07
9th page
K = 0.000, A4 = -1.20530e-03, A6 = 4.76630e-05, A8 = 3.56052e-06, A10 = -3.27440e-07
13th page
K = 0.000, A4 = -3.65098e-04, A6 = -1.10814e-05, A8 = 5.00000e-07, A10 = 0.000
17th page
K = 0.000, A4 = 4.08721e-03, A6 = 1.30182e-04, A8 = 6.78774e-05, A10 = 0.000
18th page
K = 0.000, A4 = 2.39177e-04, A6 = 0.000, A8 = 0.000, A10 = 0.000
19th page
K = 0.000, A4 = 2.99096e-04, A6 = -7.39489e-06, A8 = 1.00000e-07, A10 = 0.000
Zoom data
Wide angle end 1st middle 2nd middle 3rd middle Telephoto end Focal length 4.48 7.16 12.31 19.75 34.39
F number 3.32 4.25 5.25 5.77 6.01
Angle of view (2ω) 90.18 58.98 35.04 22.25 12.87
Image height (IH) 3.88 3.88 3.88 3.88 3.88
When focusing at infinity
d5 0.28 1.67 5.39 9.08 13.11
d11 7.91 5.46 3.84 2.43 1.00
d17 3.51 8.14 12.68 14.76 15.85
d19 5.56 4.90 4.23 5.04 4.49
BF 5.56 4.90 4.23 5.04 4.49
Total lens length 32.05 34.96 40.94 46.10 49.24
Zoom lens group data Group Start point Focal length
1 1 26.06
2 6 -4.59
3 13 8.07
4 18 20.20

Numerical Example 4
Scaling ratio 7.678
Unit mm
Surface data surface number r d nd νd
1 38.663 0.70 1.84666 23.78
2 18.693 2.30 1.72916 54.68
3 173.192 0.10
4 17.894 1.65 1.77250 49.60
5 49.455 Variable
6 49.455 0.40 1.88300 40.76
7 4.200 2.00
8 (Aspherical surface) -12.689 0.30 1.80610 40.92
9 (Aspherical) 10.540 0.45
10 9.987 1.25 1.94595 17.98
11 -72.121 Variable
12 (brightness stop) ∞ -0.15
13 (Aspherical) 4.622 1.60 1.72903 54.04
14 (Aspherical) 38.238 0.60
15 14.962 0.40 1.74000 28.30
16 2.820 1.51 1.58313 59.38
17 (Aspherical) 21.592 Variable
18 (Aspherical) 24.850 1.80 1.52542 55.78
19 (Aspherical surface) -18.029 Variable Image surface (imaging surface) ∞
Aspheric data 8th surface
K = 0.000, A4 = -5.84040e-04, A6 = 6.35121e-05, A8 = -1.56673e-06, A10 = -5.23868e-08
9th page
K = 0.000, A4 = -7.46223e-04, A6 = 8.77942e-05, A8 = -2.72720e-06, A10 = -1.36689e-08
13th page
K = 0.000, A4 = -1.07466e-03, A6 = -4.45638e-05, A8 = -1.23980e-05, A10 = 0.000
14th page
K = 0.000, A4 = -1.76786e-03, A6 = -3.08437e-05, A8 = -1.19289e-05, A10 = 0.000
17th page
K = 0.000, A4 = 4.23594e-03, A6 = 1.55776e-04, A8 =, A10 = 2.34972e-05
18th page
K = 0.000, A4 = -6.10465e-05, A6 = -6.87396e-06, A8 = 0.000, A10 = 0.000
19th page
K = 0.000, A4 = -6.89988e-05, A6 = -2.07358e-05, A8 = 4.08940e-07, A10 = 0.000
Zoom data
Wide angle end 1st middle 2nd middle 3rd middle Telephoto end Focal length 4.48 7.72 11.99 20.45 34.39
F number 3.41 4.66 5.39 5.69 6.10
Angle of view (2ω) 89.60 55.73 36.19 21.62 12.90
Image height (IH) 3.88 3.88 3.88 3.88 3.88
When focusing at infinity
d5 0.30 1.41 4.93 9.72 13.04
d11 7.90 5.07 3.81 2.24 0.95
d17 3.00 9.13 12.28 13.20 15.20
d19 5.88 4.93 4.67 5.71 4.30
BF 5.88 4.93 4.67 5.71 4.30
Total lens length 31.99 35.44 40.59 45.77 48.39
Zoom lens group data Group Start point Focal length
1 1 25.60
2 6 -4.68
3 13 8.14
4 18 20.18

Numerical Example 5
Scaling ratio 7.679
Unit mm
Surface data surface number r d nd νd
1 38.389 0.70 1.84666 23.78
2 18.720 2.30 1.72916 54.68
3 174.162 0.10
4 17.763 1.65 1.77250 49.60
5 48.728 Variable
6 48.728 0.38 1.88300 40.76
7 4.200 2.00
8 (Aspherical surface) -12.370 0.30 1.80610 40.92
9 (Aspherical) 10.282 0.45
10 10.030 1.25 1.94595 17.98
11 -61.462 Variable
12 (brightness stop) ∞ -0.15
13 (Aspherical) 4.662 1.48 1.72903 54.04
14 (Aspherical) 40.611 0.56
15 14.869 0.40 1.74000 28.30
16 2.820 1.50 1.58313 59.38
17 (Aspherical) 21.900 Variable
18 (Aspherical) 24.473 1.80 1.52542 55.78
19 (Aspherical surface) -17.580 Variable Image surface (imaging surface) ∞
Aspheric data 8th surface
K = 0.000, A4 = -5.76003e-04, A6 = 5.61105e-05, A8 = -2.90414e-06, A10 = 7.15536e-08
9th page
K = 0.000, A4 = -7.93734e-04, A6 = 8.63973e-05, A8 = -5.06571e-06, A10 = 1.89661e-07
13th page
K = 0.000, A4 = -1.68575e-03, A6 = -2.22584e-05, A8 = -4.81539e-05, A10 = 1.69955e-06
14th page
K = 0.000, A4 = -2.78536e-03, A6 = -1.04604e-04, A8 = -2.55778e-05, A10 = 0.000
17th page
K = 0.000, A4 = 4.69268e-03, A6 = 2.25015e-04, A8 = 1.83012e-05, A10 = 0.000
18th page
K = 0.000, A4 = -2.33512e-05, A6 = -6.87396e-06, A8 = 0.000, A10 = 0.000
19th page
K = 0.000, A4 = -1.58478e-06, A6 = -2.07358e-05, A8 = 4.08940e-07, A10 = 0.000
Zoom data
Wide angle end 1st middle 2nd middle 3rd middle Telephoto end Focal length 4.48 7.62 11.72 20.35 34.39
F number 3.46 4.65 5.39 5.70 6.10
Angle of view (2ω) 89.61 56.03 36.85 21.65 12.85
Image height (IH) 3.88 3.88 3.88 3.88 3.88
When focusing at infinity
d5 0.30 1.69 4.92 9.73 13.06
d11 7.87 5.23 3.90 2.23 0.95
d17 3.31 9.18 12.28 13.28 15.23
d19 5.85 4.85 4.69 5.82 4.30
BF 5.85 4.85 4.69 5.82 4.30
Total lens length 32.05 35.67 40.51 45.78 48.26
Zoom lens group data Group Start point Focal length
1 1 25.41
2 6 -4.66
3 13 8.19
4 18 19.76

Numerical Example 6
Scaling ratio 7.671
Unit mm
Surface data surface number r d nd νd
1 38.494 0.70 1.84666 23.78
2 18.424 2.30 1.72916 54.68
3 174.535 0.10
4 18.541 1.65 1.77250 49.60
5 56.114 Variable
6 56.114 0.38 1.88300 40.76
7 4.358 1.98
8 (Aspherical surface) -12.107 0.30 1.80610 40.92
9 (Aspherical surface) 9.729 0.45
10 9.833 1.25 1.94595 17.98
11 -61.737 Variable
12 (brightness stop) ∞ -0.15
13 (Aspherical) 4.553 1.50 1.72903 54.04
14 (Aspherical) 33.072 0.58
15 15.300 0.40 1.74000 28.30
16 2.810 1.50 1.58313 59.38
17 (Aspherical) 23.559 Variable
18 (Aspherical) 22.066 1.80 1.52542 55.78
19 (Aspherical surface) -18.930 Variable image surface (imaging surface) ∞
Aspheric data 8th surface
K = 0.000, A4 = -3.70895e-04, A6 = 8.13149e-05, A8 = -7.28619e-06, A10 = 1.96038e-07
9th page
K = 0.000, A4 = -6.62356e-04, A6 = 1.40568e-04, A8 = -1.43723e-05, A10 = 5.60694e-07
13th page
K = 0.000, A4 = -1.69801e-03, A6 = -1.06464e-04, A8 = -2.07738e-05, A10 = 0.000
14th page
K = 0.000, A4 = -2.78564e-03, A6 = -1.70970e-04, A8 =, A10 = -5.21132e-06
17th page
K = 0.000, A4 = 4.71618e-03, A6 = 2.98438e-04, A8 = -9.52536e-07, A10 = 0.000
18th page
K = 0.000, A4 = -1.04154e-04, A6 = -6.87396e-06, A8 = 0.000, A10 = 0.000
19th page
K = 0.000, A4 = -6.90074e-05, A6 = -2.07358e-05, A8 = 4.08940e-07, A10 = 0.000
Zoom data
Wide angle end 1st middle 2nd middle 3rd middle Telephoto end Focal length 4.48 7.70 11.72 20.39 34.39
F number 3.46 4.64 5.37 5.69 6.10
Angle of view (2ω) 89.41 55.22 36.63 21.40 12.74
Image height (IH) 3.88 3.88 3.88 3.88 3.88
When focusing at infinity
d5 0.30 1.78 4.91 9.79 13.04
d11 7.88 5.18 3.91 2.28 0.95
d17 3.31 9.12 12.23 13.27 15.24
d19 5.78 4.89 4.67 5.67 4.36
BF 5.78 4.89 4.67 5.67 4.36
Total lens length 32.00 35.70 40.45 45.74 48.33
Zoom lens group data Group Start point Focal length
1 1 25.42
2 6 -4.66
3 13 8.16
4 18 19.69

Numerical Example 7
Scaling ratio 7.679
Unit mm
Surface data surface number r d nd νd
1 38.511 0.70 1.84666 23.78
2 18.454 2.30 1.72916 54.68
3 194.513 0.10
4 18.573 1.65 1.77250 49.60
5 54.421 Variable
6 54.421 0.37 1.88300 40.76
7 4.268 1.96
8 (Aspherical surface) -12.631 0.30 1.80610 40.92
9 (Aspherical surface) 9.860 0.45
10 9.876 1.25 1.94595 17.98
11 -63.656 Variable
12 (brightness stop) ∞ -0.15
13 (Aspherical surface) 4.184 1.46 1.72903 54.04
14 17.326 0.63
15 18.052 0.40 1.74000 28.30
16 2.861 1.54 1.58313 59.38
17 (Aspherical) 44.580 Variable
18 (Aspherical) 19.500 1.80 1.52542 55.78
19 (Aspherical surface) -21.392 Variable image surface (imaging surface) ∞
Aspheric data 8th surface
K = 0.000, A4 = -4.09226e-04, A6 = 6.34122e-05, A8 = -7.85199e-06, A10 = 4.80326e-07
9th page
K = 0.000, A4 = -6.07347e-04, A6 = 7.89944e-05, A8 = -7.92708e-06, A10 = 5.25157e-07
13th page
K = 0.000, A4 = -1.96114e-04, A6 = -2.95945e-05, A8 = 1.83443e-06, A10 = 0.000
17th page
K = 0.000, A4 = 3.69952e-03, A6 = 1.95268e-04, A8 = 2.77399e-05, A10 = 0.000
18th page
K = 0.000, A4 = -1.60120e-04, A6 = -6.87396e-06, A8 = 0.000, A10 = 0.000
19th page
K = 0.000, A4 = -1.23694e-04, A6 = -2.07358e-05, A8 = 4.08940e-07, A10 = 0.000
Zoom data
Wide angle end 1st middle 2nd middle 3rd middle Telephoto end Focal length 4.48 7.75 11.70 20.54 34.39
F number 3.48 4.59 5.37 5.88 6.10
Angle of view (2ω) 89.21 54.32 36.64 21.25 12.71
Image height (IH) 3.88 3.88 3.88 3.88 3.88
When focusing at infinity
d5 0.30 2.39 4.99 9.61 13.13
d11 7.89 5.28 3.87 2.28 0.95
d17 3.31 8.73 12.03 14.03 15.13
d19 5.74 4.91 4.83 5.48 4.36
BF 5.74 4.91 4.83 5.48 4.36
Total lens length 32.01 36.08 40.49 46.16 48.34
Zoom lens group data Group Start point Focal length
1 1 25.45
2 6 -4.66
3 13 8.19
4 18 19.71

Numerical Example 8
Scaling ratio 7.686
Unit mm
Surface data surface number r d nd νd
1 44.718 0.70 1.84666 23.78
2 20.044 2.25 1.72916 54.68
3 411.851 0.10
4 18.238 1.67 1.77250 49.60
5 51.283 Variable
6 51.283 0.30 1.88300 40.76
7 4.801 1.90
8 (Aspherical surface) -15.754 0.30 1.80490 40.81
9 (Aspherical surface) 7.449 0.67
10 9.436 1.29 1.94595 17.98
11 -1560.337 Variable
12 (brightness stop) ∞ -0.15
13 (Aspherical) 4.249 1.25 1.69350 53.20
14 32.074 1.10
15 32.262 0.40 1.74077 27.76
16 3.216 1.18 1.58313 59.38
17 (Aspherical surface) 71.501 Variable
18 21.455 1.85 1.53071 55.70
19 (Aspherical surface) -19.921 Variable Image surface (imaging surface) ∞
Aspheric data 8th surface
K = 0.000, A4 = -1.86991e-04, A6 = -8.41011e-05, A8 = 1.36180e-05, A10 = -5.85128e-07
9th page
K = 0.000, A4 = -3.74748e-04, A6 = -1.06392e-04, A8 = 2.06266e-05, A10 = -9.74844e-07
13th page
K = 0.000, A4 = -2.97587e-04, A6 = -1.25578e-05, A8 = 5.00000e-07, A10 = 0.000
17th page
K = 0.000, A4 = 3.59685e-03, A6 = 2.06353e-04, A8 = 3.46210e-05, A10 = 0.000
19th page
K = 0.000, A4 = 5.04902e-05, A6 = -1.09401e-05, A8 = 2.68045e-07, A10 = 0.000
Zoom data
Wide angle end 1st middle 2nd middle 3rd middle Telephoto end Focal length 4.48 7.16 11.70 20.10 34.44
F number 3.44 4.31 5.17 5.86 6.10
Angle of view (2ω) 89.95 58.15 36.46 21.76 12.75
Image height (IH) 3.88 3.88 3.88 3.88 3.88
When focusing at infinity
d5 0.28 2.36 5.59 9.45 13.26
d11 7.85 5.69 4.01 2.36 1.02
d17 3.49 7.94 11.66 14.48 15.64
d19 5.65 4.88 4.73 5.46 4.51
BF 5.65 4.88 4.73 5.46 4.51
Total lens length 32.08 35.68 40.80 46.56 49.24
Each group focal length zoom lens group data Group Start point Focal length
1 1 25.82
2 6 -4.60
3 13 8.17
4 18 19.77

Numerical Example 9
Scaling ratio 7.674
Unit mm
Surface data surface number r d nd νd
1 43.231 0.70 1.84666 23.78
2 20.389 2.18 1.72916 54.68
3 316.659 0.10
4 17.606 1.69 1.72916 54.68
5 50.286 Variable
6 50.286 0.30 1.88300 40.76
7 4.945 1.86
8 (Aspherical surface) -15.098 0.30 1.80490 40.81
9 (Aspherical surface) 7.155 0.70
10 9.403 1.29 1.94595 17.98
11 -1215.866 Variable
12 (brightness stop) ∞ -0.15
13 (Aspherical) 4.182 1.24 1.69350 53.20
14 26.573 1.13
15 36.699 0.40 1.74077 27.76
16 3.239 1.19 1.58313 59.38
17 (Aspherical) 183.542 Variable
18 (Aspherical) 24.295 1.85 1.53071 55.70
19 (Aspherical surface) -17.542 Variable image surface (imaging surface) ∞
Aspheric data 8th surface
K = 0.000, A4 = -7.23941e-04, A6 = 6.88620e-05, A8 = -7.67332e-07, A10 = -9.02970e-08
9th page
K = 0.000, A4 = -9.18743e-04, A6 = 4.78455e-05, A8 = 5.05804e-06, A10 = -4.21452e-07
13th page
K = 0.000, A4 = -3.53985e-04, A6 = -1.50812e-05, A8 = 5.00000e-07, A10 = 0.000
17th page
K = 0.000, A4 = 3.53665e-03, A6 = 2.45405e-04, A8 = 2.83855e-05, A10 = 0.000
18th page
K = 0.000, A4 = 1.95648e-04, A6 = 0.000, A8 = 0.000, A10 = 0.000
19th page
K = 0.000, A4 = 2.21492e-04, A6 = -4.33938e-06, A8 = 3.37844e-08, A10 = 0.000
Zoom data
Wide angle end 1st middle 2nd middle 3rd middle Telephoto end Focal length 4.48 7.19 12.30 20.10 34.39
F number 3.41 4.28 5.35 6.00 6.05
Angle of view (2ω) 89.89 58.11 34.97 21.89 12.83
Image height (IH) 3.88 3.88 3.88 3.88 3.88
When focusing at infinity
d5 0.28 2.37 5.64 9.12 13.26
d11 7.85 5.66 3.97 2.41 1.02
d17 3.48 7.94 12.78 15.39 15.64
d19 5.65 4.90 4.17 5.0 4.568
BF 5.65 4.90 4.17 5.08 4.56
Total lens length 32.05 35.66 41.34 46.78 49.26
Each group focal length zoom lens group data Group Start point Focal length
1 1 25.93
2 6 -4.60
3 13 8.17
4 18 19.49

Numerical Example 10
Scaling ratio 7.679
Unit mm
Surface data surface number r d nd νd
1 43.343 0.70 1.84666 23.78
2 20.444 2.18 1.72916 54.68
3 304.501 0.10
4 17.591 1.69 1.72916 54.68
5 50.627 Variable
6 50.627 0.30 1.88300 40.76
7 4.957 1.86
8 (Aspherical surface) -15.210 0.30 1.80490 40.81
9 (Aspherical surface) 7.136 0.70
10 9.481 1.29 1.94595 17.98
11 -749.491 Variable
12 (brightness stop) ∞ -0.15
13 (Aspherical) 4.186 1.24 1.69350 53.20
14 26.529 1.14
15 36.340 0.40 1.74077 27.76
16 3.250 1.19 1.58313 59.38
17 (Aspherical) 191.909 Variable
18 (Aspherical surface) 24.179 1.85 1.53071 55.70
19 (Aspherical surface) -17.711 Variable Image surface (imaging surface) ∞
Aspheric data 8th surface
K = 0.000, A4 = -6.70000e-04, A6 = 7.18000e-05, A8 = -5.10000e-07, A10 = -1.76921e-07
9th page
K = 0.000, A4 = -8.82272e-04, A6 = 4.68940e-05, A8 = 7.13773e-06, A10 = -6.94415e-07
13th page
K = 0.000, A4 = -4.05229e-04, A6 = -1.43659e-06, A8 = 5.00000e-07, A10 = 0.000
17th page
K = 0.000, A4 = 3.59330e-03, A6 = 1.84052e-04, A8 = 4.65187e-05, A10 = 0.000
18th page
K = 0.000, A4 = 1.92496e-04, A6 = 0.000, A8 = 0.000, A10 = 0.000
19th page
K = 0.000, A4 = 2.28534e-04, A6 = -6.63740e-06, A8 = 1.10000e-07, A10 = 0.000
Zoom data
Wide angle end 1st middle 2nd middle 3rd middle Telephoto end Focal length 4.48 7.18 12.30 20.11 34.39
F number 3.39 4.26 5.32 5.97 6.02
Angle of view (2ω) 89.97 58.15 35.00 21.90 12.84
Image height (IH) 3.88 3.88 3.88 3.88 3.88
When focusing at infinity
d5 0.28 2.37 5.64 9.13 13.26
d11 7.85 5.67 3.97 2.41 1.02
d17 3.49 7.94 12.78 15.39 15.64
d19 5.64 4.88 4.14 5.03 4.51
BF 5.64 4.88 4.14 5.03 4.51
Total lens length 32.04 35.64 41.30 46.73 49.21
Zoom lens group data Group Start point Focal length
1 1 25.93
2 6 -4.60
3 13 8.16
4 18 19.56

  Aberration diagrams at the time of focusing on infinity in Examples 1 to 10 are shown in FIGS. In these aberration diagrams, (a) shows the wide-angle end, (b) shows the second intermediate focal length state, and (c) shows spherical aberration SA, astigmatism AS, distortion DT, and lateral chromatic aberration CC at the telephoto end. In each aberration diagram, “IH” represents the image height.

Next, the corresponding values of the conditional expressions (1) to (10) and (A) to (D) in the above embodiments will be shown.
Conditional Example Example 1 Example 2 Example 3 Example 4 Example 5
(1) 0.327 0.306 0.315 0.323 0.328
(2) 0.236 0.221 0.227 0.232 0.236
(3) 0.417 0.390 0.399 0.403 0.414
(4) 4.362 4.588 4.509 4.504 4.411
(5) 0.256 0.255 0.258 0.145 0.141
(6) 0.094 0.092 0.093 0.082 0.082
(7) 1.00 1.00 1.00 1.00 1.00
(8) 0.077 0.077 0.077 0.103 0.099
(9) 1.878 1.878 1.878 1.878 1.878
(10) 1.332 1.262 1.290 1.269 1.286
(A) 0.007 0.008 0.007 0.001 0.002
(B) -1.026 -1.016 -1.016 -1.300 -1.296
(C) -31.6 -31.6 -31.6 -31.1 -31.1
(D) 0.072 0.072 0.072 0.077 0.077
(E) 7.679 7.680 7.678 7.678 7.679

Conditional Example Example 6 Example 7 Example 8 Example 9 Example 10
(1) 0.329 0.328 0.321 0.326 0.325
(2) 0.237 0.236 0.233 0.236 0.235
(3) 0.414 0.416 0.413 0.419 0.417
(4) 4.391 4.400 4.411 4.349 4.367
(5) 0.145 0.157 0.280 0.286 0.286
(6) 0.082 0.083 0.093 0.094 0.094
(7) 1.00 1.00 1.00 1.00 1.00
(8) 0.098 0.097 0.077 0.077 0.077
(9) 1.878 1.878 1.878 1.878 1.878
(10) 1.291 1.291 1.306 1.330 1.325
(A) 0.004 0.003 0.003 0.007 0.008
(B) -1.271 -1.137 -1.094 -1.036 -1.034
(C) -31.1 -31.1 -31.6 -31.6 -31.6
(D) 0.077 0.077 0.072 0.072 0.072
(E) 7.671 7.679 7.686 7.674 7.679

  In each embodiment, the following configuration may be adopted.

In the zoom lenses of the above-described embodiments, an image in which barrel distortion occurs is formed on a rectangular photoelectric conversion surface (imaging surface) at the wide-angle end. On the other hand, the occurrence of distortion is suppressed near the intermediate focal length state and at the telephoto end. In order to correct distortion occurring in the vicinity of the wide-angle end by image processing, the effective imaging area may have a barrel shape at the wide-angle end and a rectangular shape at the intermediate focal length state or the telephoto end. In this case, the effective imaging area set in advance is image-converted by image processing, and converted into rectangular image information with reduced distortion. Therefore, the image height IHw at the wide-angle end is smaller than the image height IHs at the intermediate focal length state and the image height IHt at the telephoto end.
Also, with such a configuration, the effective diameter of the first lens group becomes even smaller, which is advantageous for reducing the diameter.

Further, it is preferable to have an image conversion unit that converts an electrical signal of an image captured by the zoom lens into an image signal in which a color shift due to magnification chromatic aberration is corrected by image processing. By electrically correcting the chromatic aberration of magnification of the zoom lens, a better image can be obtained.
The chromatic aberration of magnification changes depending on the zoom state and the focus state, but for each lens position (zoom state and focus state), the shift amount of the second primary color and the third primary color from the first primary color is stored as correction data in the memory holding device. It is good to leave it. By referring to the correction data according to the zoom position, it is possible to output the second and third primary color signals in which the deviation of the second and third primary colors from the first primary color signal is corrected.

Further, in order to cut unnecessary light such as ghost and flare, a flare stop other than the brightness stop may be arbitrarily arranged.
You may arrange | position in any place between the object side of a 1st lens group, between 1st and 2nd lens groups, and the group from the most image surface side group to an image surface.
The frame member may be configured to cut flare rays, or another member may be configured. Also, it may be printed directly on the optical system, painted, or bonded with a seal. The shape may be any shape such as a circle, an ellipse, a rectangle, a polygon, or a range surrounded by a function curve. Further, not only the unnecessary light flux but also the light flux such as coma flare around the screen may be cut.

  In addition, ghost and flare may be reduced by applying an antireflection coating on the air contact surface and the joint surface of each lens. A multi-coat is desirable because it can effectively reduce ghost and flare. By appropriately combining two or more layers of coating materials and film thicknesses, it becomes possible to further reduce the reflectance and control the spectral characteristics and angular characteristics of the reflectance. In addition, an antireflection structure with a concavo-convex pattern at the operating wavelength level may be formed on the lens surface. Moreover, you may perform an infrared cut coat on a lens surface, a cover glass, etc.

FIGS. 21A and 21B are schematic views of a lens-integrated digital camera using the zoom lens of the present invention and using a small CCD or C-MOS, particularly a back-illuminated C-MOS, as an image sensor. It is sectional drawing. FIG. 21A is a schematic diagram of the use state (in the drawing, the wide-angle end use state), and FIG. 21B is a schematic diagram of the zoom lens retracted.
21 (a) and 21 (b), reference numeral 1 denotes a camera, and 2 denotes a photographic lens system according to the present invention which is disposed in a lens barrel having a zooming mechanism and a focusing mechanism.
Reference numeral 3 denotes an image sensor having an image sensor surface (imaging surface) I. Between the photographing lens system 2 and the image pickup element surface 3, a filter F such as a dustproof filter, an infrared cut filter, and a low-pass filter for removing dust by vibration, and a cover glass C for protecting the image pickup surface are disposed.
Between the third lens group G3 and the fourth lens group G4, a polyolefin ND filter ND that can be inserted and retracted for exposure control is disposed. During zooming, the effective diameter of the ND filter is reduced by moving together with the third lens group.

  As the photographing lens system 2 of the camera 1 having such a configuration, for example, the zoom lens of the present invention shown in the first embodiment is used.

In the zoom lens of each embodiment, each lens group moves independently, and zooming from the wide-angle end to the telephoto end is possible. In addition, when the lens is retracted, the third lens group G3 follows the locus of the arrow in FIG. 21 (a) and retracts away from the optical axis of the other lens groups as shown in FIG. 21 (b). it can.
In addition, when the lens is retracted, the polyolefin-based ND filter ND is retracted to the side opposite to the direction in which the third lens group G3 is retracted. You may make it retract | save integrally with the 3rd lens group G3.

In addition, the zoom lens of each embodiment can be an interchangeable lens of a lens interchangeable digital camera. You may apply to the surveillance camera which requires a wide angle of view.
An example of the invention different from the present invention is shown below.
(Additional item 1)
In order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refractive power A fourth lens group,
When zooming from the wide-angle end to the telephoto end,
The distance between the first lens group and the second lens group increases,
The distance between the second lens group and the third lens group is reduced,
The distance between the third lens group and the fourth lens group changes,
The fourth lens group includes one positive lens,
A zoom lens satisfying the following conditional expressions (1), (10-1), and (E-1):
0.25 <| f12W | / f4 <0.34 (1)
1.306 ≦ f1 / f4 <1.4 (10-1)
7.0 <ft / fw <20.0 (E-1)
However,
f12W is the focal length of the combined system of the first lens group and the second lens group at the wide-angle end,
f4 is a focal length of the fourth lens group,
f1 is the focal length of the first lens group,
ft is the focal length of the entire zoom lens system at the wide-angle end,
fw is the focal length of the entire zoom lens system at the wide-angle end
It is.
(Appendix 2)
2. The zoom lens according to appendix 1, wherein the following conditional expression (2) is satisfied.
0.2 <| f2 | / f4 <0.25 (2)
However,
f2 is a focal length of the second lens group,
It is.
(Additional Item 3)
The zoom lens according to Additional Item 1 or 2, wherein the following conditional expression (3) is satisfied.
0.35 <f3 / f4 <0.45 (3)
However,
f3 is the focal length of the third lens group
It is.
(Appendix 4)
4. The zoom lens according to any one of additional items 1 to 3, wherein the following conditional expression (4) is satisfied.
4 <f4 / fw <5 (4)
However,
f4 is a focal length of the fourth lens group,
fw is the focal length of the entire zoom lens system at the wide-angle end
It is.
(Appendix 5)
The zoom lens according to claim 4, wherein the fourth lens group moves in the optical axis direction during focusing.
(Appendix 6)
4. The zoom lens according to appendix 3, wherein the third lens group includes a lens having an aspherical surface whose positive refractive power decreases as the distance from the optical axis increases.
(Appendix 7)
7. The zoom lens according to claim 1, further comprising an aspherical lens having an aspherical surface with a negative refractive power that decreases as the second lens group moves away from the optical axis.
(Appendix 8)
The zoom lens according to appendix 7, wherein the aspheric lens is a double-sided aspheric lens.
(Appendix 9)
The zoom lens according to appendix 7 or 8, wherein the aspheric lens is a negative lens that satisfies the following conditional expression (A).
ASP1−ASP2> 0 (A)
However,
ASP1 is the amount of aspherical deviation at the principal ray passage position that reaches the maximum image height on the object side surface of the aspherical lens at the wide-angle end,
ASP2 is an aspherical deviation amount at the passing position of the principal ray reaching the maximum image height on the image side surface of the aspherical lens at the wide angle end.
(Appendix 10)
The second lens group includes, in order from the object side, a negative meniscus lens having a convex surface directed toward the object side, a biconcave negative lens, and a positive lens. The described zoom lens.
(Appendix 11)
The third lens group includes a positive lens and a cemented lens,
The zoom lens according to any one of additional items 1 to 10, wherein the cemented lens includes a negative lens and a positive lens.
(Appendix 12)
When zooming from the wide-angle end to the telephoto end,
The first lens group moves so as to be positioned on the object side at the telephoto end with respect to the position at the wide-angle end,
The second lens group moves including a locus that moves toward the image side after moving toward the object side,
The zoom lens according to any one of appendices 1 to 11, wherein the third lens group moves so as to be positioned on the object side at the telephoto end with respect to the position at the wide-angle end.
(Additional Item 13)
The zoom lens according to any one of appendices 1 to 12, wherein the second lens group satisfies the following conditional expression (D).
0.05 <D12 / IH <0.15 (D)
However,
D12 is the air spacing on the optical axis of the first lens group and the second lens group at the wide-angle end,
IH is the image height on the imaging surface by the zoom lens.
It is.
(Appendix 14)
Any one of Additional Items 1 to 13, wherein the zoom lens can be retracted and the third lens group is stored while being decentered with respect to an optical axis of another lens when the retracted lens is stored. The zoom lens according to item 1.

G1 ... 1st lens group G2 ... 2nd lens group G3 ... 3rd lens group G4 ... 4th lens group S ... Brightness stop I ... Image plane (imaging surface)
DESCRIPTION OF SYMBOLS 1 ... Camera 2 ... Shooting lens system 3 ... Image pick-up element F ... Filters C ... Cover glass ND ... Polyolefin-type ND filter

Claims (14)

In order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive A fourth lens group having refractive power,
When zooming from the wide-angle end to the telephoto end,
The distance between the first lens group and the second lens group increases,
The distance between the second lens group and the third lens group is reduced,
The distance between the third lens group and the fourth lens group changes,
A zoom lens satisfying the following conditional expressions (1), (3-1), and (10-1).
0.25 <| f12W | / f4 <0.34 (1)
0.413 ≦ f3 / f4 <0.42 (3-1)
1.306 ≦ f1 / f4 <1.4 (10-1)
However,
f12W is the focal length of the combined system of the first lens group and the second lens group at the wide-angle end,
f1 is the focal length of the first lens group,
f3 is a focal length of the third lens group,
f4 is a focal length of the fourth lens group,
It is. The zoom lens according to claim 1, wherein the following conditional expression (2) is satisfied.
0.2 <| f2 | / f4 <0.25 (2)
However,
f2 is a focal length of the second lens group,
It is. The zoom lens according to claim 1, wherein the following conditional expression (4) is satisfied.
4 <f4 / fw <5 (4)
However,
f4 is a focal length of the fourth lens group,
fw is the focal length of the entire zoom lens system at the wide angle end.   The zoom lens according to claim 3, wherein the fourth lens group moves in the optical axis direction during focusing.   2. The zoom lens according to claim 1, further comprising: an aspherical lens having a shape in which a positive refractive power becomes weaker as the third lens group moves away from the optical axis.   6. The zoom lens according to claim 1, further comprising: an aspherical lens having an aspherical surface in which the negative refractive power is weakened as the second lens group moves away from the optical axis.   The zoom lens according to claim 6, wherein the aspheric lens is a double-sided aspheric lens. The zoom lens according to claim 6 or 7, wherein the aspheric lens is a negative lens that satisfies the following conditional expression (A).
ASP1−ASP2> 0 (A)
However,
ASP1 is the amount of aspherical deviation at the principal ray passage position that reaches the maximum image height on the object side surface of the aspherical lens at the wide-angle end,
ASP2 is an aspherical deviation amount at the passing position of the principal ray reaching the maximum image height on the image side surface of the aspherical lens at the wide angle end.   9. The first lens group according to claim 1, wherein the second lens group includes, in order from the object side, a negative meniscus lens having a convex surface directed toward the object side, a biconcave negative lens, and a positive lens. The described zoom lens. The third lens group includes, in order from the object side, a positive meniscus lens having a convex surface directed toward the object side, or bonding lens consisting of a positive lens having a convex surface directed toward the negative meniscus lens and the object side with a convex surface on the object side The zoom lens according to claim 1, comprising:   The zoom lens according to any one of claims 1 to 10, wherein the fourth lens group includes one positive lens. When zooming from the wide-angle end to the telephoto end,
The first lens group moves so as to be positioned on the object side at the telephoto end with respect to the position at the wide-angle end,
The second lens group moves including a locus that moves toward the image side after moving toward the object side,
The third lens group moves so as to be located on the object side at the telephoto end with respect to the position at the wide-angle end ,
12. The zoom according to claim 1, wherein the fourth lens group moves to the object side after moving to the image side, and further moves including a locus moving to the image side. lens. The zoom lens according to claim 1, wherein the second lens group satisfies the following conditional expression (D).
0.05 <D12 / IH <0.15 (D)
However,
D12 is the air spacing on the optical axis of the first lens group and the second lens group at the wide-angle end,
IH is the image height on the imaging surface by the zoom lens.   14. The zoom lens according to claim 1, wherein the zoom lens can be retracted, and the third lens group is retracted and stored with respect to an optical axis of another lens when the retracted lens is retracted. The zoom lens according to item 1.

Images