JP2001033700A - Zoom lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens constitution effective for realizing a high magnification, miniaturization, and high image quality, in a zoom lens used for a video camera for usual life. SOLUTION: This zoom lens is composed, in order from the object side, of a first lens group having positive refractive power, fixed normally, and comprising a joined lens joined with a concave lens L1 and a convex lens L2, and a convex lens L3, a second lens group having negative refractive power, movable positionally for variable power, and comprising a concave lens L4 and a joined lens joined with a concave lens L5 and a convex lens L6, a third lend group having positive refractive power, fixed normally, and comprising a convex lens L7, and a fourth lens group having positive refractive power, movable for correction of focal point movement resulting from the variable power and focusing, and comprising a joined lens joined with a convex lens L8, a concave lens L9 and a convex lens L10. The third lens group includes at least one face constituted of an aspheric surface, and a face nearmost to the object side in the fourth lens group is composed at least of an aspheric surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens for a consumer video camera, which has a small size, a high magnification, and
The present invention relates to a technique for providing a high-quality lens configuration.

[0002]

2. Description of the Related Art An example of a four-group inner focus zoom lens having a relatively high zoom ratio of 6 times or more, which is conventionally used in a consumer video camera, and has the least number of lens components practically. 37, as shown in FIG. 37, a first lens group GR1 including a cemented lens of the first lens L1 of the concave meniscus lens and the second lens L2 of the convex lens and a third lens L3 of the convex meniscus lens, and a concave meniscus lens Of the fourth lens L4 and the fifth of the concave lens
A second lens group GR2 composed of a cemented lens of a lens L5 and a sixth convex lens L6;
There is a nine-lens zoom lens a having a third lens group GR3 including a lens L7 and a fourth lens group GR4 including a cemented lens of an eighth lens L8 of a concave lens and a ninth lens L9 of a convex lens.

In the conventional zoom lens a, since the third lens group GR3 is not a so-called achromatic lens, the chromatic aberration generated in the third lens group GR3 is reduced by the fourth lens group G3.
The overall balance was achieved by excessively correcting chromatic aberration at R4.

However, the first lens group G generated during zooming
Aberration fluctuations such as chromatic aberration and spherical aberration of R1 can be corrected by the reverse aberration generated in the second lens group GR2 so as to cancel them, but the chromatic aberration generated by moving the fourth lens group GR4 In addition, the bending due to the color of the spherical aberration cannot be canceled.

It is necessary to use a glass material constituting each lens of the fourth lens group GR4 such that the difference in Abbe number between the eighth lens L8 which is a concave lens and the ninth lens L9 which is a convex lens is as large as possible. In addition, the curvature of the joint surface between the eighth lens L8 and the ninth lens L9 is also adjusted so that the chromatic aberration can be corrected to an allowable range at the wide-angle end.
And the distribution of the refracting power of the ninth lens L9 is dependently determined from the chromatic aberration, thereby limiting the degree of freedom that can be taken.

Therefore, the bending due to the color of the spherical aberration generated by the movement of the fourth lens group GR4 is determined by the glass material, the refractive power distribution, and the curvature of the joint surface between the eighth lens L8 and the ninth lens L9. Therefore, there was almost no freedom of correction.

A nine-lens lens system like the conventional zoom lens a is practical when the zoom ratio is low, there is no need to reduce the size, and the F-number can be dark.
It was impossible to achieve high magnification, miniaturization, and high image quality.

In order to increase the magnification of the zoom lens a, if the entire refractive power is distributed so that the position of the fourth lens group GR4 at the wide-angle end and the telephoto end with respect to the object point at infinity is substantially the same, The amount of movement of the fourth lens group GR4 at the focal position becomes extremely large, and the variation in chromatic aberration becomes remarkable. This variation in chromatic aberration cannot be corrected because there is no freedom in designing the fourth lens group as described above.

In order to reduce the size of the zoom lens a, it is effective to increase the refractive power of each lens unit and reduce the amount of movement of the movable lens unit.
When the refracting power of (2) becomes strong, the Petzval's sum is largely a negative value and largely over-corrected, so that there is a disadvantage that it is difficult to correct the field curvature. If the refractive power of each lens group is strong, various aberrations including spherical aberration, in particular, aberrations due to cancellation of the first lens group GR1 and the second lens group GR2 become strong, and good performance is obtained over the entire zoom range. Becomes difficult.

Therefore, conventionally, in order to mainly reduce the spherical aberration generated from the first lens group, it has been common practice to increase the refractive index of the third lens L3 which is a convex lens. However, increasing the refractive index of the third lens L3, which is a convex lens of the first lens group GR1, has the effect of further reducing the Petzval sum of the entire lens to the negative side, and suppresses the occurrence of aberrations unique to the first lens group GR1. There is a drawback in that it is not compatible with the above and to increase the refracting power of each lens unit to reduce the size.

The fourth lens group GR of the zoom lens a
4 is to realize the aspherical surface with a glass mold,
Because of the ease of molding, it could be formed only on the surface of the ninth lens which was a convex lens. For example, even when a composite spherical surface is formed of an ultraviolet curable resin, since the glass material used for the eighth lens L8, which is a concave lens, does not transmit ultraviolet light, it can be formed only on the surface of the ninth lens L9. The degree of freedom was restricted, and it was not possible to increase the number of surfaces constituted by aspherical surfaces effective for improving image quality.

[0012]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a zoom lens used in a consumer video camera, which lens structure is effective for high magnification, miniaturization, and high image quality. That is the task.

[0013]

In order to solve the above problems, the present invention provides, in order from the object side, a first lens group having a positive refractive power and a fixed position at all times; A second lens group whose position is movable mainly for zooming, and a third lens group which has a positive refractive power and whose position is always fixed.
In a zoom lens composed of a lens group and a fourth lens group having a positive refractive power and a movable position for correcting and focusing a focal position by zooming, the first lens group is an object. The second lens group includes a cemented lens formed by joining a first lens of a concave meniscus lens having a convex surface toward the object side and a second lens of the convex lens in order from the side, and a third lens having a convex meniscus lens having a convex surface facing the object side. In order from the object side,
The fourth lens of the concave meniscus lens having the convex surface directed to the object side and the cemented lens of the fifth lens of the biconcave lens and the sixth lens of the convex lens, and the third lens group is composed of the seventh lens of the convex lens. The lens group includes, in order from the object side, a cemented lens of an eighth lens of a convex lens whose convex surface faces the object side, a ninth lens of a concave lens, and a tenth lens of a convex lens, and the third lens group is formed of an aspheric surface. The fourth lens group includes at least one surface, and at least the most object side surface is formed by an aspheric surface.

Therefore, in the present invention, the ninth concave lens for achromatism in the third lens unit and the fourth lens unit is used.
Since the refractive power of the lens is determined by the achromatic condition, it is close to the characteristics of the ninth lens of the above-mentioned conventional example. Can be greatly increased as compared with the conventional case, and in particular, it is the same as the conventional example that the cemented surface of the convex lens with the tenth lens has the convex surface facing the object side. Regardless, the curvature can be designed to be gentler than that of the conventional example, so that the curvature due to the color of the spherical aberration generated from this surface can be remarkably improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A zoom lens according to the present invention comprises, in order from the object side, a first lens having a positive refractive power and a fixed position at all times.
A lens group GR1, a second lens group GR2 having a negative refractive power and movable in position mainly for zooming, and a third lens group having a positive refractive power and a fixed position at all times G
R3 and a fourth lens group GR having a positive refractive power and movable for focal point correction and focusing by zooming.
4.

In the zoom lens of the present invention, the first lens group G1 is, in order from the object side, a cemented lens of a first lens L1 of a concave meniscus lens having a convex surface facing the object side and a second lens L2 of the convex lens and an object. The second lens group G includes a third lens L3 of a convex meniscus lens having a convex surface facing the side.
R2 includes, in order from the object side, a fourth lens L4 of a concave meniscus lens having a convex surface facing the object side, and a cemented lens of a fifth lens L5 of a biconcave lens and a sixth lens L6 of a convex lens, and the third lens group GR3 is The seventh lens L7 of the convex lens
The fourth lens group GR4 is composed of, in order from the object side, a cemented lens of an eighth lens L8 of a convex lens whose convex surface faces the object side, a ninth lens L9 of a concave lens, and a tenth lens L10 of a convex lens. The lens group GR3 includes at least one surface formed by an aspheric surface.
The fourth lens group GR4 has at least the most object side surface formed of an aspherical surface.

In the zoom lens of the present invention, it is preferable that 1.8 <n9 (conditional expression 1) is satisfied, where n9 is the refractive index of the ninth lens L9 at the d-line.

Conditional expression 1 defines the glass material of the ninth lens L9, which is a concave lens, in the fourth lens group GR4. That is, by increasing the refractive index of the ninth lens L9, the eighth lens L, which is a front and rear convex lens, is formed.
The curvature of the cemented surface between the eighth lens and the tenth lens L10 is reduced to suppress the fluctuation of the chromatic aberration and the spherical aberration caused by the movement of the fourth lens group GR4, and to correct the Petzval sum to the plus side. This is advantageous for correction of field curvature.

In the case of a zoom lens having a zoom ratio of about 10 and aiming at miniaturization and high image quality, the third lens group GR
An aperture IR is arranged between the third lens unit GR4 and the fourth lens unit GR4, the most image-side surface of the fourth lens unit GR4 is formed by an aspheric surface, and f2 is a focal length of the second lens unit GR2, f
If 3 is the focal length of the third lens group GR3, f4 is the focal length of the fourth lens group GR4, and fw is the focal length of the entire lens system at the wide-angle end, 1.1 <f3 / f4 <1.4 (condition It is desirable to satisfy each condition of Expression 2) and 1.0 <| f2 / fw | <1.3 (conditional expression 3).

Conditional expression 2 defines the relationship between the focal lengths of the third lens group GR3 and the fourth lens group GR4.

That is, the value of f3 / f4 is the lower limit.
When the value is 1 or less, it becomes difficult to suppress the fluctuation of the spherical aberration, or the moving amount of the fourth lens group GR4 increases, and the overall length of the entire lens system (zoom lens) increases. Conversely, if the value of f3 / f4 is equal to or greater than the upper limit value of 1.4, aberration deterioration due to a manufacturing error of the fourth lens group GR4 will undesirably appear, which is not preferable.

Conditional expression 3 defines the relationship between the focal length of the second lens group GR2 and the focal length of the entire lens system at the wide-angle end.

That is, when the value of | f2 / fw | is less than or equal to the lower limit of 1.0, aberration deterioration due to variations in the manufacture of the second lens group GR2 becomes noticeable. Conversely, if the value of | f2 / fw | is 1.3 or more, which is the upper limit, the amount of movement of the second lens group GR2 during zooming becomes large, which is not preferable for downsizing the zoom lens. .

Further, by arranging the stop IR between the third lens group GR3 and the fourth lens group GR4, the distance between the second lens group GR2 and the third lens group GR3 at the telephoto end can be shortened. Can be made incident on the third lens group GR3 while the height of the marginal ray emitted from the second lens group is low, so that the total length of the zoom lens can be reduced. Become.

In the case of a high-magnification zoom lens having a zoom ratio of about 25 times, and the purpose of making the overall length shorter than the focal length at the telephoto end, the third lens group GR3 should have its convex surface facing the object side. And fw is the focal length of the entire lens system at the wide-angle end, dz
Is the amount of movement of the second lens group GR2 during zooming, f3 is the focal length of the third lens group GR3, and f4 is the focal length of the fourth lens group GR4. 8.5 <dz / fw <10 (conditional expression) 4), 1.2 <f3 / f4 <1.45 (conditional expression 5)

Conditional expression 4 represents the second condition from the wide-angle end to the telephoto end.
This defines the relationship between the amount of movement of the lens group GR2 and the focal length of the entire lens system at the wide-angle end.

That is, the value of dz / fw is the lower limit.
If the ratio is 5 or less, it is necessary to increase the refractive power of the second lens group GR2 in order to obtain a high zoom ratio of 25 times or more, and accordingly, the Petzval sum is greatly corrected to the negative side and excessively corrected. Therefore, it is impossible to correct the curvature of field of the entire lens system only by selecting the glass material. Conversely, dz /
If the value of fw exceeds the upper limit value of 10 or more, the total length of the zoom lens becomes longer, and the second lens group GR
It becomes difficult to move 2 without eccentricity, and it becomes impractical.

Conditional expression 5 defines the relationship between the focal lengths of the third lens unit GR3 and the fourth lens unit GR4.
Shows the optimum range when is adapted to a zoom lens having a zoom ratio of about 25.

That is, the value of f3 / f4 is the lower limit.
If it is less than 2, the refractive power of the third lens group GR3 will be too strong, and the refractive power of the fourth lens group GR4 will be too weak. If the refractive power of the third lens group GR3 is too strong, the spherical aberration will be insufficiently corrected at the wide-angle end, and it will be difficult to correct the spherical aberration fluctuation during focusing even in the intermediate focus area. Also, if the refractive power of the fourth lens group GR4 becomes too weak, the amount of movement of the fourth lens group GR4 during focusing becomes large, the aberration fluctuation becomes large, and the back focus becomes longer than necessary. It is not suitable for downsizing zoom lenses. Conversely, when the value of f3 / f4 is equal to or more than the upper limit value of 1.45, the refractive power of the third lens group GR3 becomes weak or the refractive power of the fourth lens group GR4 becomes too strong. If the refractive power of the third lens group GR3 is too weak, spherical aberration at the wide-angle end is excessively corrected, which is not preferable. On the other hand, if the refractive power of the fourth lens group GR4 becomes too strong, the spherical aberration at the wide-angle end becomes insufficiently corrected, which is not preferable.

If the zoom lens is a high-magnification zoom lens having a zoom ratio of about 25 and the overall length is slightly longer than the focal length at the telephoto end due to the downsizing of the image pickup device, the third lens group GR3 should be convex toward the object side. , And fw is the focal length of the entire lens system at the wide-angle end,
dz is the amount of movement of the second lens group GR2 during zooming, Lz is the distance from the most object side surface of the entire lens system at the telephoto end to the most image side surface of the second lens group GR2, and Lf is the Assuming that the distance from the surface closest to the image plane of the three lens group GR3 to the image plane of the entire lens system is 8.5 <dz / fw <11 (conditional expression 6), 1.8 <Lz / Lf <2.2 It is desirable to satisfy each condition of (conditional expression 7).

Conditional expression 6 defines the relationship between the amount of movement of the second lens group GR2 from the wide-angle end to the telephoto end and the focal length of the entire lens system at the wide-angle end, similarly to conditional expression 4. .

That is, the value of dz / fw is the lower limit.
If either of 5 and 11 is exceeded, conditional expression 4
However, even when the size of the imaging device is reduced, the thickness of the concave lens, the edge thickness of the convex lens, and the like increase in proportion to the miniaturization of the imaging device due to manufacturing reasons. Cannot be thin. Therefore, in order to achieve both the miniaturization of the image sensor and the restriction that the lens configuration factor cannot be reduced in thickness, the refraction of the second lens group GR2 is determined by the conditional expression 6 in which the upper limit value of the conditional expression 4 is increased from 10 to 11. It is preferred to determine the force arrangement.

Conditional expression 7 is for reducing a useless space for realizing size reduction while maintaining a high magnification ratio of about 25 times, and the second lens group GR at the time of zooming.
This defines the conditions relating to the amount of movement of the second lens group and the amount of movement of the fourth lens group GR4 during compensation and focusing.

That is, the value of Lz / Lf is the lower limit.
If it is less than 8, the amount of movement of the second lens group GR2 must be smaller than the amount of movement of the fourth lens group GR4, and the refractive power of the second lens group GR2 needs to be increased. For this reason, the Petzval sum is greatly overcorrected to a negative value, and it becomes impossible to correct the curvature of field of the entire lens system only by selecting the glass material. Conversely, Lz / L
When the value of f is 2.2 or more, which is the upper limit, the amount of movement of the second lens group GR2 becomes larger than the amount of movement of the fourth lens group GR4, so that the overall length of the zoom lens is longer and the front lens system is larger. It becomes impractical.

In the case of a zoom lens having a zoom ratio of about 10 and aiming to make the overall length and the front lens system as small as possible corresponding to a small image pickup device, the third lens group GR3
An aperture IR is arranged between the third lens group GR4 and the third lens group GR4.
The seventh group of convex lenses in which the lens group GR3 is convex toward the object side.
And at least one of the surfaces constituting the first lens group GR1 is constituted by an aspheric surface, and n3 is a refractive index of the third lens L3 at d-line,
fw is the focal length of the entire lens system at the wide-angle end, dz is the amount of movement of the second lens group GR2 during zooming, and f3 is the third lens group G.
Assuming that the focal length of R3 and f4 are the focal length of the fourth lens group GR4, 1.58 <n3 <1.7 (conditional expression 8), 2.5 <dz / fw <5 (conditional expression 9), It is desirable to satisfy each condition of 2 <f3 / f4 <1.8 (conditional expression 10).

Conditional expression 8 is to prevent the Petzval sum from being excessively over-corrected at a negative value due to miniaturization.
This stipulates conditions for satisfying good correction of spherical aberration inherent to the lens group GR1.

In order to improve the refractive power of each lens unit and increase the Petzval sum with a negative value,
It is effective to lower the refractive index of the convex lens and increase the refractive index of the concave lens. However, in the first lens group GR1, lowering the refractive index of the second lens L2 of the cemented convex lens is caused by other aberrations. It can be easily done without affecting the correction,
If the refractive index of the third lens L3, which is a convex lens, is reduced, it is difficult to correct spherical aberration generated from the first lens group GR1,
In particular, it becomes difficult to correct spherical aberration on the telephoto side.

For this reason, it is common to increase the refractive index of the third lens L3 to prevent the image quality from deteriorating on the telephoto side. However, increasing the refractive index of the third lens L3 is equivalent to the Petzval sum. Is set to the negative side, and in order to prevent this, the refractive power of each lens unit must be reduced. That is, Petzval sum and miniaturization cannot be achieved at the same time.

Therefore, in order to correct the Petzval sum, the refractive index n3 of the third lens L3 is set to 1.7 or less, which is the upper limit, and the deterioration of the spherical aberration accompanying this is caused by the aspheric surface of the first lens group GR1. The problem was solved by introducing.
However, when the refractive index n3 is equal to or less than the lower limit of 1.58, the curvature of the reference spherical surface of the third lens L3 is too strong, and it becomes difficult to correct spherical aberration with good balance even for an aspheric surface.

Conditional expression 9 defines the same conditions as in conditional expressions 4 and 6, except that dz / fw is set to be as small as possible with a zoom ratio of about 10 times.
Is made lower so that the amount of movement of the second lens group GR2 can be reduced. However, dz / f
When the value of w is equal to or less than the lower limit of 2.5, it is necessary to increase the refractive power of the second lens group GR2 in order to obtain a zoom ratio of about 10 as in the case of the conditional expression 4. Accordingly, the Petzval sum is largely overcorrected on the negative side, and the correction of the curvature of field of the entire lens system cannot be performed only by selecting the glass material. Conversely, if the value of dz / fw is 5 or more, which is the upper limit, as in the case of Conditional Expression 4, the overall length of the zoom lens becomes longer, and the second lens group GR2 is moved without being decentered. It becomes difficult and impractical.

Conditional expression 10 is obtained by adjusting the condition defined by conditional expression 2 in the same manner as conditional expression 5 in accordance with the balance between the zoom ratio of about 10 times and the miniaturization, and f3 / f
When the value of 4 is less than or equal to the lower limit of 1.2, the refractive power of the third lens group GR3 becomes too strong, and the refractive power of the fourth lens group GR4 becomes too weak, as in the case of the conditional expression 5. Would. If the refractive power of the third lens group GR3 is too strong, the spherical aberration will be insufficiently corrected at the wide-angle end, and it will be difficult to correct the spherical aberration fluctuation during focusing even in the intermediate focus area. Also, if the refractive power of the fourth lens group GR4 becomes too weak, the amount of movement of the fourth lens group GR4 during focusing becomes large, the aberration fluctuation becomes large, and the back focus becomes longer than necessary. It is not suitable for downsizing zoom lenses. Conversely, when the value of f3 / f4 is equal to or more than the upper limit of 1.8, the refractive power of the third lens group GR3 becomes weak, as in the case of the conditional expression 5.
The refracting power of the fourth lens group GR4 becomes too strong. If the refractive power of the third lens group GR3 is too weak, spherical aberration at the wide-angle end is excessively corrected, which is not preferable. On the other hand, if the refractive power of the fourth lens group GR4 becomes too strong, the spherical aberration at the wide-angle end becomes insufficiently corrected, which is not preferable.

Next, Numerical Examples 1 to 9 specifically showing the zoom lens of the present invention will be described with reference to the accompanying drawings.

In the following description, "ri" is the ith surface and its radius of curvature counted from the object side, and "di" is the distance between the ith surface and the (i + 1) th surface counted from the object side. Surface distance (lens thickness or air space), “ni” is the refractive index of the i-th lens at the d-line, “νi” is the Abbe number of the i-th lens at the d-line, “f” is the focal length of the entire lens system,
“FNo.” Indicates an open F value, and “ω” indicates a half angle of view (“nFL” and “νFL” are a refractive index and an Abbe number of a filter described later, respectively).

The lenses used in the numerical examples include those having a lens surface formed of an aspherical surface. The aspherical surface shape is as follows, where "X" is the coordinates of the aspherical surface in the optical axis direction, "C" is the paraxial curvature, and "Y" is the distance from the optical axis. X = (C.Y ² ) / ｛1+ ( 1-C ² · Y ² ) ^1/2 ｝ + A4
Shall be defined by the ^{· Y 4 + A6 · Y 6} + A8 · Y 8 + A10 · Y 10. Here, A4, A6,
A8 and A10 are the respective orders (fourth, sixth, eighth and tenth orders).
The following is the aspheric coefficient.

The zoom lenses 1 and 2 according to the first numerical example and the second numerical example aim at a zoom ratio of about 10 times and miniaturization, and are shown in FIG. 1 and FIG. Thus, in order from the object side, the first lens group GR1 having a positive refractive power and the position is always fixed, and the second lens group having a negative refractive power and being movable mainly for zooming. Lens group GR2
And a third lens group G having a positive refractive power and a fixed position at all times
R3 and a fourth lens group GR having a positive refractive power and movable for focal point correction and focusing by zooming.
The stop IR is disposed between the third lens group GR3 and the fourth lens group GR4. Note that a filter FL such as a low-pass filter is disposed between the fourth lens group GR4 and the image plane IMG.

In addition, the zoom lenses 1 and 2 are arranged such that the first lens group GR1 is formed by, in order from the object side, a first lens L1 of a concave meniscus lens whose convex surface faces the object side and a second lens L2 of the convex lens.
A cemented lens with the lens L2 and a third lens L3 of a convex meniscus lens having a convex surface facing the object image,
The second lens group GR2 includes, in order from the object side, a fourth lens L4 of a concave meniscus lens having a convex surface facing the object side, and a cemented lens of a fifth lens L5 of a biconcave lens and a sixth lens L6 of a convex lens. , The third lens group GR3
Is constituted by a seventh lens L7 of a convex lens, and the fourth lens group GR4 is constituted by an eighth lens L8 of a convex lens whose convex surface faces the object side in order from the object side and a ninth lens L9 of a concave lens
And the tenth lens L10 of the convex lens, and the most object-side surface r11 of the third lens group GR3.
And the surface r14 closest to the object side of the fourth lens group GR4 and the surface r17 closest to the image plane IMG of the fourth lens group GR4,
Each is constituted by an aspherical surface.

Further, the zoom lenses 1 and 2 satisfy the above-mentioned conditional expressions 1, 2, and 3, respectively.

Table 1 shows each numerical value of the zoom lens 1.

[0049]

[Table 1]

As shown in Table 1 above, the zoom lens 1
Is the surface distance d by zooming and focusing.
5, d10, d13 and d17 are variable. Therefore, the following Table 2 shows the wide-angle end (f = 1.00), the intermediate focal length position between the wide-angle end and the telephoto end (f = 4.72), and the telephoto end (f = 9.73) during zooming. And the numerical values of the surface spacings d5, d10, d14, and d17 at FNo. And f.

[0051]

[Table 2]

Further, the seventh lens L of the third lens group GR3
The object-side surface r11 of the seventh lens, the object-side surface r17 of the eighth lens of the fourth lens group GR4, and the image surface IMG-side surface r17 of the tenth lens L10 are formed as aspherical surfaces. Table 3
Shows the fourth, sixth, eighth and tenth order aspherical coefficients A4, A6, A8 and A10 of the surfaces r11, r14 and r17.

[0053]

[Table 3]

FIGS. 2 to 4 show the wide-angle end of the zoom lens 1,
FIG. 3 shows a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at an intermediate focal length position between the wide-angle end and the telephoto end and at the telephoto end, respectively. In the spherical aberration diagram, the solid line is the d line (wavelength 58
7.6 nm), the broken line indicates the value at the g-line (wavelength 435.8 nm), and in the astigmatism diagram, the solid line indicates the value on the sagittal image plane, and the broken line indicates the value on the meridional image plane (FIGS. 6 to 8). The same).

Table 4 shows each numerical value of the zoom lens 2.

[0056]

[Table 4]

As shown in Table 4 above, the zoom lens 2
Is the surface distance d by zooming and focusing.
5, d10, d14, and d17 are variable. Accordingly, Table 5 below shows the wide-angle end (f = 1.00), the intermediate focal length position between the wide-angle end and the telephoto end (f = 4.07), and the telephoto end (f = 9.56) during zooming. , And the numerical values of the surface spacings d5, d10, d13, and d17, and FNo. And f.

[0058]

[Table 5]

Further, the seventh lens L of the third lens group GR3
The object-side surface r11 of the seventh lens, the object-side surface r17 of the eighth lens of the fourth lens group GR4, and the image surface IMG-side surface r17 of the tenth lens L10 are formed as aspherical surfaces. Table 6
Shows the fourth, sixth, eighth and tenth order aspherical coefficients A4, A6, A8 and A10 of the surfaces r11, r14 and r17.

[0060]

[Table 6]

FIGS. 6 to 8 show the zoom lens 2 at the wide-angle end.
FIG. 3 shows a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at an intermediate focal length position between the wide-angle end and the telephoto end and at the telephoto end, respectively.

As described above, the zoom lenses 1 and 2
The FNo. And various aberrations were satisfactorily corrected over the entire zoom range while having a high zoom ratio of approximately 10 times.
It is a small and lightweight zoom lens with excellent optical performance that is optimal for still cameras, video cameras, and the like.

The zoom lenses 3 and 4 in the third and fourth numerical examples are intended to satisfactorily correct various aberrations with a high zoom ratio of 25 times or more and a small number of components. As shown in FIGS. 9 and 13, in order from the object side, a first lens group GR1 having a positive refractive power and a fixed position at all times, and a negative refractive power and a position mainly for zooming, A movable second lens group GR2 and a third lens group GR3 having a positive refractive power and a fixed position at all times.
A fourth position having a positive refractive power and movable for focal position correction and focusing by zooming.
In the zoom lens constituted by the lens group GR4, the first lens group GR1 includes, in order from the object side, a cemented lens of a first lens L1 of a concave meniscus lens having a convex surface facing the object side and a second lens L2 of a convex lens; The second lens group GR2 includes, in order from the object side, a fourth lens L4 of a concave meniscus lens having a convex surface facing the object side and a fifth lens L4 of a biconcave lens having a convex surface facing the object side. The lens L5 and the sixth lens L6 of the convex lens
The third lens group GR3 is composed of a seventh lens L7 of a convex lens having a convex surface facing the object side,
The fourth lens group GR4 includes, in order from the object side, a cemented lens of an eighth lens L8 of a convex lens having a convex surface facing the object side, a ninth lens L9 of a concave lens, and a tenth lens L10 of a convex lens.

The zoom lenses 3 and 4 perform zooming by moving the second lens group GR2 and the fourth lens group GR4. When zooming from the wide-angle end to the telephoto end, Second lens group G
R2 moves from the object side to the image plane side, and the fourth lens group GR
Reference numeral 4 moves so as to maintain the image position. Focusing of the zoom lenses 3 and 4 is performed by moving the fourth lens group GR4.

The second lens group GR2 and the third lens group G
An aperture IR is arranged between the lens group R3 and R3, and a filter FL such as a low-pass filter is arranged between the fourth lens group GR4 and the image plane IMG.

Further, the zoom lenses 3 and 4 are designed to satisfy the conditional expressions 1, 4 and 5.

FIG. 9 shows a zoom lens 3 in a third numerical example.

Table 7 below shows various numerical values of the zoom lens 3.

[0069]

[Table 7]

In Table 7 above, the distances d5, d10,
d13 and d17 are variable with zooming and focusing. Accordingly, Table 8 below shows the FNo. At the wide-angle end (f = 3.79595), the intermediate focal length position between the wide-angle end and the telephoto end (f = 34.7895), and the telephoto end (f = 95.6720). , D5, d10,
The numerical values of d13 and d17 are shown.

[0071]

[Table 8]

In the third lens group GR3 and the fourth lens group GR4, the object-side surface r12 of the seventh lens L7 and the object-side surface r14 of the eighth lens L8 are formed by aspheric surfaces. Table 9 shows the values of the four surfaces r12 and r14.
Next, sixth, eighth and tenth order aspherical coefficients A4, A6, A
8 and A10 are shown.

[0073]

[Table 9]

Note that "E" in Table 9 means an exponential expression with a base of 10 (the same applies to the following tables showing aspheric coefficients).

FIGS. 10 to 12 show a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end, an intermediate focal length position between the wide-angle end and the telephoto end, and the telephoto end of the zoom lens 3, respectively. In the astigmatism diagram, the solid line shows the value on the sagittal image plane, and the broken line shows the value on the meridional image plane (the same applies to FIGS. 14 to 16).

FIG. 13 shows a zoom lens 4 according to a fourth numerical example.

Table 10 below shows various numerical values of the zoom lens 4.

[0078]

[Table 10]

In Table 10 above, the surface distances d5 and d1
0, d13, and d17 change with zooming and focusing. Therefore, Table 11 below shows the wide-angle end (f = 3.8000), the intermediate focal length position between the wide-angle end and the telephoto end (f = 33.44884), and the telephoto end (f = 38.884).
90.8307). , D5, d10, d13
And d17 are shown.

[0080]

[Table 11]

In the third lens group GR3 and the fourth lens group GR4, the image-side surface r13 of the seventh lens L7 and the object-side surface r14 of the eighth lens L8 are aspherical. Table 12 shows the values of the four surfaces r13 and r14.
Next, sixth, eighth and tenth order aspherical coefficients A4, A6, A
8 and A10 are shown.

[0082]

[Table 12]

FIGS. 14 to 16 show a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end, an intermediate focal length position between the wide-angle end and the telephoto end, and the telephoto end of the zoom lens 4, respectively.

Table 13 below shows the numerical values of the conditional expressions 4 and 5 of the zoom lenses 3 and 4 shown in the third and fourth numerical examples.

[0085]

[Table 13]

The zoom lenses 3 and 4 in the third and fourth numerical examples satisfy the conditional expressions 1, 4 and 5 so that 10 elements in 6 groups of 4 groups zoom. With the lens system having the configuration, various aberrations can be favorably corrected with a small number of components, and a zoom lens optimal for a video camera having a high zoom ratio of 25 times or more can be obtained.

The zoom lenses 5, 6, and 7 in the fifth, sixth, and seventh numerical embodiments aim to satisfactorily correct various aberrations with a high zoom ratio of 25 times or more and a small number of components. 17, a first lens group GR1 having a positive refractive power and a fixed position at all times, and a negative refractive power, in order from the object side, as shown in FIGS. A second lens group GR2 whose position is movable mainly for zooming, a third lens group GR3 which has a positive refractive power and whose position is always fixed, and a zoom lens which has a positive refractive power and has a positive refractive power. In a zoom lens constituted by a fourth lens group GR4 whose position is movable for correction of a focal position and focusing, the first lens group GR1 is a concave meniscus having a convex surface facing the object side in order from the object side. The first lens L1 of the lens The second lens group GR2 includes, in order from the object side, a concave meniscus lens having a convex surface facing the object side, the lens being a cemented lens of the lens with the second lens L2 and a third lens L3 of a convex meniscus lens having a convex surface facing the object side. The fourth lens L4, the fifth lens L5 of a biconcave lens, and a cemented lens of a sixth lens L6 of a convex lens, the third lens group GR3 includes a seventh lens L7 of a convex lens having a convex surface facing the object side, The fourth lens group GR4 includes, in order from the object side, an eighth lens L8 of a convex lens having a convex surface facing the object side, a ninth lens L9 of a concave lens, and a tenth lens L of a convex lens.
10 and a cemented lens.

The zoom lenses 5, 6, and 7 are
The zooming is performed by moving the lens group GR2 and the fourth lens group GR4. When zooming from the wide-angle end to the telephoto end, the second lens group GR2 moves from the object side to the image plane side. Then, the fourth lens group GR4 moves so as to maintain the image position. Focusing of the zoom lenses 5, 6 and 7 is
This is performed by moving the fourth lens group GR4.

The second lens group GR2 and the third lens group G
R3 or between the third lens group GR3 and the fourth lens group GR
An aperture IR is arranged between the lens group 4 and a filter FL such as a low-pass filter is arranged between the fourth lens group GR4 and the image plane IMG.

Further, the zoom lenses 5, 6, and 7
The lens group GR3 has at least one aspheric surface.
The fourth lens group GR4 includes a surface, and the most object-side surface of the fourth lens group GR4 is also formed of an aspherical surface, and satisfies the conditional expressions 1, 6, and 7.

FIG. 17 shows the zoom lens 5 in the fifth numerical example.

Table 14 below shows various numerical values of the zoom lens 5.

[0093]

[Table 14]

In Table 14, the surface distances d5 and d1
0, d13 and d17 are variable with zooming and focusing. Accordingly, Table 15 below shows that the FNo. At the wide-angle end (f = 1.00), the intermediate focal length position between the wide-angle end and the telephoto end (f = 12.48), and the telephoto end (f = 24.92). , D5, d10, d1
The numerical values of 3 and d17 are shown.

[0095]

[Table 15]

In the third lens group GR3 and the fourth lens group GR4, the object-side surface r12 of the seventh lens L7 and the object-side surface r14 of the eighth lens L8 are formed as aspheric surfaces. Table 16 shows the values of the four surfaces r12 and r14.
Next, sixth, eighth and tenth order aspherical coefficients A4, A6, A
8 and A10 are shown.

[0097]

[Table 16]

18 to 20 show a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end, an intermediate focal length position between the wide-angle end and the telephoto end, and the telephoto end of the zoom lens 5, respectively. In the astigmatism diagram, a solid line indicates a value on a sagittal image plane, and a broken line indicates a value on a meridional image plane (the same applies to FIGS. 22 to 24 and FIGS. 26 to 28).

FIG. 21 shows a zoom lens 6 according to a sixth numerical example.

Table 17 below shows various numerical values of the zoom lens 6.

[0101]

[Table 17]

In Table 17, the surface distances d5 and d1
0, d13, and d17 change with zooming and focusing. Accordingly, Table 18 below shows the wide-angle end (f = 1.00), the intermediate focal length position (f = 12.45) between the wide-angle end and the telephoto end, and the telephoto end (f = 24.8).
4) FNo. , D5, d10, d13 and d17 are shown.

[0103]

[Table 18]

In the third lens group GR3 and the fourth lens group GR4, the object-side surface r12 of the seventh lens L7 and the object-side surface r14 of the eighth lens L8 are formed by aspheric surfaces. Table 19 shows the values of the four surfaces r12 and r14.
Next, sixth, eighth and tenth order aspherical coefficients A4, A6, A
8 and A10 are shown.

[0105]

[Table 19]

FIGS. 22 to 24 show a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end, an intermediate focal length position between the wide-angle end and the telephoto end, and the telephoto end of the zoom lens 6, respectively.

FIG. 25 shows a zoom lens 7 according to a seventh numerical example.

Table 20 below shows various numerical values of the zoom lens 7.

[0109]

[Table 20]

In Table 20, the surface distances d5 and d1
0, d13, and d17 change with zooming and focusing. Accordingly, Table 21 below shows the wide-angle end (f = 1.0000), the intermediate focal length position between the wide-angle end and the telephoto end (f = 12.4771), and the telephoto end (f =
No. 24.9113). , D5, d10, d13
And d17 are shown.

[0111]

[Table 21]

In the third lens group GR3 and the fourth lens group GR4, the object-side surface r12 of the seventh lens L7 and the object-side surface r14 of the eighth lens L8 are formed by aspheric surfaces. Table 22 shows the values of the four surfaces r12 and r14.
Next, sixth, eighth and tenth order aspherical coefficients A4, A6, A
8 and A10 are shown.

[0113]

[Table 22]

FIGS. 26 to 28 show a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end, an intermediate focal length position between the wide-angle end and the telephoto end, and the telephoto end of the zoom lens 7, respectively.

Table 23 below shows the fifth numerical example,
The numerical values of the conditional expressions 6 and 7 of the zoom lenses 5, 6, and 7 shown in the sixth numerical example and the seventh numerical example are shown.

[0116]

[Table 23]

The zoom lenses 5, 6, and 7 in the fifth, sixth, and seventh numerical embodiments described above satisfy conditional expressions 1, 6, and 7 by satisfying conditional expressions 1, 6, and 7. With a 10-element lens system consisting of 6 groups of 4 groups, various aberrations can be satisfactorily corrected with a small number of elements, and a zoom lens optimal for a video camera having a high zoom ratio of 25 times or more can be obtained. It is.

The zoom lenses 8 and 9 in the eighth and ninth numerical embodiments aim at a zoom ratio of 10 times or more and miniaturization, and as shown in FIGS. A first lens group GR1 having a positive refractive power and a fixed position at all times, and a second lens group GR2 having a negative refractive power and being movable mainly for zooming in order.
A third lens group GR3 having a positive refractive power and a fixed position at all times, and a fourth lens group GR having a positive refractive power and a movable position for correcting and focusing a focal position by zooming. In the zoom lens constituted by the lens group GR4, the first lens group GR1 includes, in order from the object side, a cemented lens of a first lens L1 of a concave meniscus lens having a convex surface facing the object side and a second lens L2 of a convex lens; The second lens group GR2 includes, in order from the object side, a fourth lens L4 of a concave meniscus lens having a convex surface facing the object side and a fifth lens L4 of a biconcave lens having a convex surface facing the object side. The third lens group GR3 is composed of a seventh lens L7 of a convex lens having a convex surface facing the object side, and is composed of a cemented lens of a lens L5 and a sixth lens L6 of a convex lens. 'S group GR4 in this order from the object side,
The eighth lens L8 of the convex lens whose convex surface faces the object side, the ninth lens L9 of the concave lens, and the tenth lens L10 of the convex lens
And a cemented lens.

The zoom lenses 8 and 9 are designed to perform zooming by moving the second lens group GR2 and the fourth lens group GR4. When zooming from the wide-angle end to the telephoto end, Second lens group G
R2 moves from the object side to the image plane side, and the fourth lens group GR
Reference numeral 4 moves so as to maintain the image position. Focusing of the zoom lenses 8 and 9 is performed by moving the fourth lens group GR4.

The third lens group GR3 and the fourth lens group G
An aperture IR is arranged between the lens group R4 and the filter FL, such as a low-pass filter, is arranged between the fourth lens group GR4 and the image plane IMG.

Further, the zoom lenses 8 and 9 each include at least one aspherical surface in the first lens group GR1 and the third lens group GR3, and the most object-side surface of the fourth lens group GR4. Conditional expression 1, Conditional expression 8, Conditional expression 9 and Conditional expression 10
Is to be satisfied.

FIG. 29 shows a zoom lens 8 in the eighth numerical example.

Table 24 below shows various numerical values of the zoom lens 8.

[0124]

[Table 24]

In Table 24, the surface distances d5 and d1
0, d13 and d17 are variable with zooming and focusing. Accordingly, Table 25 below shows the FNo. At the wide-angle end (f = 2.3706), the intermediate focal length position between the wide-angle end and the telephoto end (f = 15.180), and the telephoto end (f = 22.4075). , D5, d1
The numerical values of 0, d13 and d17 are shown.

[0126]

[Table 25]

In the first lens group GR1, the third lens group GR3, and the fourth lens group GR4, the third lens L
The object-side surface r4 of No. 3 and the object-side surface r1 of the seventh lens L7
The first surface r14 of the eighth lens L8 on the object side is formed of an aspheric surface. Table 26 shows the fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients A of the surfaces r4, r11, and r14.
4, A6, A8 and A10 are shown.

[0128]

[Table 26]

FIGS. 30 to 32 show a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end, an intermediate focal length position between the wide-angle end and the telephoto end, and the telephoto end of the zoom lens 8, respectively. In the astigmatism diagram, the solid line indicates the value on the sagittal image plane, and the broken line indicates the value on the meridional image plane (the same applies to FIGS. 34 to 36).

FIG. 33 shows the zoom lens 9 in the ninth numerical example.

Table 27 below shows various numerical values of the zoom lens 9.

[0132]

[Table 27]

In Table 27, the surface distances d5 and d1
0, d13, and d17 change with zooming and focusing. Accordingly, Table 28 below shows the wide-angle end (f = 2.2550), the intermediate focal length position between the wide-angle end and the telephoto end (f = 14.6362), and the telephoto end (f =
21.3154). , D5, d10, d13
And d17 are shown.

[0134]

[Table 28]

In the first lens group GR1, the third lens group GR3, and the fourth lens group GR4, the third lens L
The object-side surface r4 of No. 3 and the object-side surface r1 of the seventh lens L7
The first surface r14 of the eighth lens L8 on the object side is formed of an aspheric surface. Table 29 shows the fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients A of the surfaces r4, r11, and r14.
4, A6, A8 and A10 are shown.

[0136]

[Table 29]

FIGS. 34 to 36 show a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end, an intermediate focal length position between the wide-angle end and the telephoto end, and the telephoto end of the zoom lens 9, respectively.

Table 30 below shows the numerical values of the conditional expressions 9 and 10 for the zoom lenses 8 and 9 shown in the eighth numerical example and the ninth numerical example.

[0139]

[Table 30]

The zoom lenses 8 and 9 in the eighth and ninth numerical embodiments satisfy the conditional expressions 1, 7, 8, and 9 to satisfy the condition (4).
With a lens system having six groups and ten lenses, it is possible to satisfactorily correct various aberrations with a small number of lenses and obtain a zoom lens optimal for a video camera having a high zoom ratio of 10 times or more. .

As described above, in the zoom lens of the present invention, since the refractive power of the ninth lens L9 of the concave lens that performs achromatism in the third lens group GR3 and the fourth lens group GR4 is determined by the achromatic condition, Example 9th lens L9
However, in the present invention, the ninth lens L9
The eighth lens L8 of the convex lens and the tenth lens
By joining with the lens L10, the ninth lens L9
Allows the degree of freedom of the curvature of the lens to be much larger than in the past, and in particular, the tenth lens L1 of the convex lens
Despite the fact that the joint surface with 0 has a convex surface facing the object side in the same manner as in the conventional example, the curvature can be designed to be looser than in the conventional example, so that the curvature due to the color of the spherical aberration generated from this surface can be reduced. Significant improvements could be made.

It should be noted that the specific shapes and structures of the respective parts shown in the above-described embodiments are merely examples for embodying the present invention, and the technical features of the present invention are not limited thereto. The scope should not be construed as limiting.

[0143]

As described above, the zoom lens according to the present invention comprises, in order from the object side, a first lens group having a positive refractive power and a fixed position at all times, and a zoom lens mainly having a negative refractive power. A second lens group whose position is movable for zooming,
A third lens group having a positive refractive power and a fixed position at all times, and a fourth lens having a positive refractive power and a movable position for correcting a focal position by focusing and focusing. The first lens group includes, in order from the object side, a cemented lens of the first lens of the concave meniscus lens having a convex surface facing the object side and the second lens of the convex lens, and a convex meniscus having a convex surface facing the object side. The second lens group includes, in order from the object side, a fourth lens of a concave meniscus lens having a convex surface facing the object side, and a cemented lens of a fifth lens of a biconcave lens and a sixth lens of a convex lens. The third lens group includes a seventh lens of a convex lens, and the fourth lens group includes an eighth lens of a convex lens whose convex surface faces the object side in order from the object side.
The third lens group includes at least one surface formed by an aspherical surface, and the fourth lens group includes at least the most object-side lens. Since the surface is formed by an aspherical surface, the curvature of the ninth lens, which is a concave lens, can be freely set, and the curvature due to the color of the spherical aberration generated from the ninth lens can be remarkably improved.

According to the second aspect of the present invention, n9
Is the refractive index at the d-line of the ninth lens, 1.8 <
Since the condition of n9 is satisfied, the curvature of the joint surface between the ninth lens and the convex lens can be reduced, which is advantageous for suppressing and correcting various aberrations.

According to the third aspect of the present invention, the third aspect
An aperture is arranged between the lens group and the fourth lens group, the most image-side surface of the fourth lens group is constituted by an aspheric surface, f2 is a focal length of the second lens group, and f3 is a third lens group. If f4 is the focal length of the fourth lens group and fw is the focal length of the entire lens system at the wide-angle end, 1.1 <f
Since each condition of 3 / f4 <1.4 and 1.0 <| f2 / fw | <1.3 is satisfied, the zoom ratio is reduced to about 10 and the various aberrations are satisfactorily corrected. Zoom lens can be obtained.

According to the fourth aspect of the present invention, the third aspect
The lens group is composed of a seventh lens of a convex lens having a convex surface facing the object side, fw is the focal length of the entire lens system at the wide-angle end, dz is the amount of movement of the second lens group when zooming, and f3 is the third lens.
Assuming that the focal length of the lens group, f4, is the focal length of the fourth lens group, 8.5 <dz / fw <10, 1.2 <f3 / f
Since each condition of 4 <1.45 is satisfied, it is possible to obtain a zoom lens having a high zoom ratio of about 25 times, a short overall length, and excellent correction of various aberrations.

According to the fifth aspect of the present invention, the third aspect
The lens group is composed of a seventh lens of a convex lens whose convex surface faces the object side, fw is the focal length of the entire lens system at the wide-angle end, dz is the amount of movement of the second lens group when zooming, and Lz is the telephoto end. If Lf is the distance from the most object-side surface of the entire lens system to the most image-side surface of the second lens unit, and Lf is the distance from the most image-side surface of the third lens unit to the image surface, then: .5 <dz
/ Fw <11, 1.8 <Lz / Lf <2.2, so that the zoom ratio is as high as about 25, and various aberrations are well corrected and the size is reduced. Thus, a zoom lens corresponding to the image pickup device can be obtained.

According to the sixth aspect of the present invention, the third aspect
An aperture is disposed between the lens group and the fourth lens group, and the third lens group is composed of a seventh lens of a convex lens having a convex surface facing the object side, n3 is a refractive index at d-line of the third lens, and fw is a wide angle. The focal length of the whole lens system at the end, the second value when dz is changed
The amount of movement of the lens group, f3, is the focal length of the third lens group, f
Assuming that 4 is the focal length of the fourth lens group, at least one of the surfaces constituting the first lens group is constituted by an aspheric surface, and 1.58 <n3 <1.7, 2.5 <d
Since each condition of z / fw <5 and 1.2 <f3 / f4 <1.8 is satisfied, the zoom ratio is about 10 times, the overall length is short, various aberrations are well corrected, and the size is small. It is possible to obtain a zoom lens corresponding to the integrated imaging device.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a zoom lens according to the present invention together with FIGS.
This figure is a view schematically showing a lens configuration.

FIG. 2 is a diagram illustrating various aberrations at a wide-angle end.

FIG. 3 is a diagram illustrating various aberrations at an intermediate focal position between a wide-angle end and a telephoto end.

FIG. 4 is a diagram illustrating various aberrations at a telephoto end.

FIG. 5 is a second view of the zoom lens of the present invention, together with FIGS. 6 to 8;
This figure is a view schematically showing a lens configuration.

FIG. 6 is a diagram illustrating various aberrations at a wide-angle end.

FIG. 7 is a diagram illustrating various aberrations at an intermediate focal position between a wide-angle end and a telephoto end.

FIG. 8 is a diagram illustrating various aberrations at a telephoto end.

9 shows a third numerical example of the zoom lens according to the present invention, together with FIGS. 10 to 12, and is a view schematically showing a lens configuration. FIG.

FIG. 10 is a diagram illustrating various aberrations at a wide-angle end.

FIG. 11 is a diagram illustrating various aberrations at an intermediate focal position between a wide-angle end and a telephoto end.

FIG. 12 is a diagram illustrating various aberrations at a telephoto end.

13 shows a fourth numerical example of the zoom lens according to the present invention, together with FIGS. 14 to 16, and is a view schematically showing a lens configuration. FIG.

FIG. 14 is a diagram illustrating various aberrations at a wide-angle end.

FIG. 15 is a diagram illustrating various aberrations at an intermediate focal position between a wide-angle end and a telephoto end.

FIG. 16 is a diagram illustrating various aberrations at a telephoto end.

FIG. 17 shows a fifth numerical example of the zoom lens according to the present invention together with FIGS. 18 to 20, and is a view schematically showing a lens configuration.

FIG. 18 is a diagram illustrating various aberrations at a wide-angle end.

FIG. 19 is a diagram illustrating various aberrations at an intermediate focal position between a wide-angle end and a telephoto end.

FIG. 20 is a diagram illustrating various aberrations at a telephoto end.

FIG. 21 shows a sixth numerical example of the zoom lens of the present invention together with FIGS. 22 to 24, and is a view schematically showing a lens configuration.

FIG. 22 is a diagram illustrating various aberrations at a wide-angle end.

FIG. 23 is a diagram illustrating various aberrations at an intermediate focal position between a wide-angle end and a telephoto end.

FIG. 24 is a diagram illustrating various aberrations at the telephoto end.

25 shows a seventh numerical example of the zoom lens according to the present invention together with FIGS. 26 to 28, and is a view schematically showing a lens configuration. FIG.

FIG. 26 is a diagram illustrating various aberrations at a wide-angle end.

FIG. 27 is a diagram illustrating various aberrations at an intermediate focal position between a wide-angle end and a telephoto end.

FIG. 28 is a diagram illustrating various aberrations at a telephoto end.

FIG. 29 shows an eighth numerical example of the zoom lens according to the present invention together with FIGS. 30 to 32, and is a view schematically showing a lens configuration.

FIG. 30 is a diagram illustrating various aberrations at a wide-angle end.

FIG. 31 is a diagram illustrating various aberrations at an intermediate focal position between a wide-angle end and a telephoto end.

FIG. 32 is a diagram illustrating various aberrations at a telephoto end.

FIG. 33 shows a ninth numerical example of the zoom lens according to the present invention together with FIGS. 34 and 35, and is a view schematically showing a lens configuration.

FIG. 34 is a diagram illustrating various aberrations at a wide-angle end.

FIG. 35 is a diagram illustrating various aberrations at an intermediate focal position between a wide-angle end and a telephoto end.

FIG. 36 is a diagram illustrating various aberrations at a telephoto end.

FIG. 37 is a diagram illustrating a lens configuration of an example of a conventional zoom lens.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... zoom lens, 2 ... zoom lens, 3 ... zoom lens, 4 ... zoom lens, 5 ... zoom lens, 6 ... zoom lens, 7 ... zoom lens, 8 ... zoom lens, 9 ... zoom lens, GR1 ... 1st lens Group, GR2: second lens group, GR3: third lens group, GR4: fourth lens group,
L1: first lens, L2: second lens, L3: third lens, L4: fourth lens, L5: fifth lens, L6: sixth
Lens, L7: Seventh lens, L8: Eighth lens, L9 ...
Ninth lens, L10: Tenth lens, IR: Aperture, IM
G: Image plane

 ──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Atsuro Minato 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Shin-ichi Arita 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo No. Inside Sony Corporation (72) Inventor Yusuke Nanjo 6-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F-term (reference) 2H087 KA03 MA08 NA14 PA06 PA20 PB10 QA02 QA07 QA17 QA21 QA25 QA34 QA42 QA45 RA05 RA12 RA13 RA42 SA23 SA27 SA29 SA32 SB04 SB14 SB22 SB34 9A001 KK16 KK42 KK54

Claims (6)

[Claims] 1. A first lens unit having a positive refractive power and a fixed position at all times, and a negative refractive power and a movable position mainly for zooming in order from the object side. A second lens group and a third lens group having a positive refractive power and a fixed position at all times.
In a zoom lens constituted by a lens group and a fourth lens group having a positive refractive power and a movable position for correcting and focusing a focal position by zooming, the first lens group is In order from the object side, the first lens of the concave meniscus lens having the convex surface facing the object side and the second lens of the convex lens
The second lens group includes, in order from the object side, a fourth lens of a concave meniscus lens having a convex surface facing the object side and a third lens of a convex meniscus lens having a convex surface facing the object side. The third lens group includes a seventh lens of a convex lens, and the fourth lens group has a convex surface directed to the object side in order from the object side, the fifth lens being a concave lens and the sixth lens being a convex lens. The third lens group includes at least one surface formed by an aspherical surface, and the third lens group includes at least one surface formed by an aspherical surface. A zoom lens, wherein at least the four lens groups have an aspherical surface at the most object side. 2. The zoom lens according to claim 1, wherein the following condition is satisfied. 1.8 <n9 where n9 is the refractive index of the ninth lens at d-line. 3. A stop is disposed between the third lens group and the fourth lens group, and the most image-side surface of the fourth lens group is formed by an aspheric surface, and satisfies the following conditions. The zoom lens according to claim 1, wherein: 1.1 <f3 / f4 <1.4 1.0 <| f2 / fw | <1.3 where f2: focal length of the second lens group, f3: focal length of the third lens group, f4: fourth. Fw: focal length of the entire lens system at the wide-angle end. 4. The zoom lens according to claim 1, wherein the third lens group comprises a seventh lens of a convex lens whose convex surface faces the object side, and satisfies the following conditions. . 8.5 <dz / fw <10 1.2 <f3 / f4 <1.45 where fw: focal length of the entire lens system at the wide-angle end, dz: moving amount of the second lens unit at the time of zooming, f3 : Focal length of the third lens group, f4: focal length of the fourth lens group. 5. The zoom lens according to claim 1, wherein the third lens group comprises a seventh lens of a convex lens whose convex surface faces the object side, and satisfies the following conditions. . 8.5 <dz / fw <11 1.8 <Lz / Lf <2.2, where fw: focal length of the entire lens system at the wide-angle end, dz: moving amount of the second lens unit during zooming, Lz : Second from the most object side surface of the entire lens system at the telephoto end
Lf: distance from the surface closest to the image plane of the third lens group to the image plane of the entire lens system. 6. A stop is arranged between the third lens group and the fourth lens group, and the third lens group is composed of a seventh lens of a convex lens whose convex surface faces the object side, and constitutes the first lens group. 2. The zoom lens according to claim 1, wherein at least one of the surfaces is formed of an aspherical surface, and the following conditions are satisfied. 1.58 <n3 <1.7 2.5 <dz / fw <5 1.2 <f3 / f4 <1.8, where n3 is the refractive index at the d-line of the third lens, and fw is the lens at the wide angle end. The focal length of the entire system, dz: the amount of movement of the second lens group during zooming, f3: the focal length of the third lens group, and f4: the focal length of the fourth lens group.