JPH0743611A - Zoom lens - Google Patents

Abstract

PURPOSE:To provide a zoom lens suitable for a video camera and a television camera, etc., using an inner focusing system having high variable power ratio and large aperture ratio. CONSTITUTION:In a zoom lens comprising a first group F having a positive refractive power, a second group V for varying power having a negative refractive power, a third group C compensating the fluctuation of an image plane due to the variable power and a fourth group R having image forming action and being fixed during varying power in order from the object side, the first group F is composed of an eleventh group F11 being fixed at the time of focusing and a twelfth group F12 moving to the object side at the time of focusing from the object at infinity to the nearest object and the lens constitution of the eleventh group F11 and the twelfth group F12, the focal distance fT and the F number FNT of the whole system at the telephoto end, the focal distance f1 and the F number FN1 of the first group F, the focal distances f11, f12 of the eleventh group F11 and the twelfth group F12 and the difference DELTAupsilonX of Abbe numbers of materials of anegative lens LN11 and a positive lens LP12, etc., are properly set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens suitable for a television camera, a video camera, a photographic camera, etc., and in particular, it uses a so-called inner focus type for focusing with a part of the first lens group, The present invention relates to a zoom lens having a wide-angle end F number of 1.6, a variable power ratio of 14 to 44 times, a large aperture ratio and a high variable power ratio, which has high optical performance over the entire object distance.

[0002]

2. Description of the Related Art In recent years, color television cameras for TV broadcasting have been emphasized in operability and mobility, and in response to such demands, image pickup devices have been downsized. For example, a small CCD of 2/3 inch or 1/2 inch. The use of (solid-state image sensor) is becoming mainstream. By doing so, the overall size and weight of the camera device is reduced.

In response to this, the zoom lens used in the color television camera for broadcasting is also downsized, and at the same time, the specifications of the zoom lens are improved.

Of the zoom lens, in order from the object side, a first group of positive refracting power for focusing (focusing), a second group of negative refracting power for zooming, and an image plane that varies with zooming. A so-called four-group zoom lens composed of four lens groups of a third lens group having a positive or negative refractive power for correcting the above and a fourth lens group having a positive refractive power for image formation has a relatively high zoom ratio and a large zoom lens. Since it is easy to adjust the aperture ratio, it is often used in zoom lenses for color television cameras for broadcasting.

In recent broadcast zoom lenses, there is a strong demand for the zoom lens to have a short focal length at the wide-angle end, a long focal length at the telephoto end, and a high zoom ratio. In addition to this, the so-called MOD (Minimum Obje
Shortening the ct distance is becoming an important factor in the specifications and image effects of zoom lenses used in broadcast TV cameras.

However, if this MOD is to be shortened, the fluctuation of various aberrations due to the focusing action in the focus range becomes a problem. In particular, spherical aberration, astigmatism, and chromatic aberration have large fluctuations, which significantly deteriorates optical performance. The variation in aberration due to this focus is as the focal length becomes longer, the F number becomes smaller and the lens system becomes brighter, and M
The shorter the OD, the more remarkable. Therefore, various ideas have been made for the focusing system of the zoom lens.

The first of the focusing methods on the object side
Various proposals have been made to adopt a so-called inner focus method, in which a part of the lens group inside the lens system other than the group is moved for focusing.

Generally, in an inner focus type zoom lens, the effective diameter of the first lens group is smaller than that of a zoom lens in which the first lens group is moved to perform focusing, which facilitates downsizing of the entire lens system and close-up photography. In particular, extremely close-up photography is facilitated, and since the relatively small and lightweight lens group is moved to perform the operation, the driving force of the lens group is small, and quick focusing is possible.

As such an inner focus type zoom lens, for example, in Japanese Patent Publication No. 52-41068, a first lens group having a positive refractive power, a second lens group having a negative refractive power for zooming, and a zooming lens are arranged in this order from the object side. In a so-called four-group zoom lens composed of four lens groups, a third lens group having a negative refractive power and a fourth lens group having a positive refractive power, for correcting the image plane variation due to the doubling,
This discloses a zoom lens in which a part of the lens group on the image plane side in the group is moved to perform focusing.

[0010]

Generally, in a zoom lens, a large aperture ratio (F number 1.6 to 5.0), a high zoom ratio (variation ratio 14 to 44), and a full zoom range and full zoom ratio are used. In order to obtain high optical performance over the focus range (total object distance), it is necessary to properly set the refractive power and lens configuration of each lens group, and the aberration sharing, the achromatic sharing, and the like.

For example, in order to obtain high optical performance with little aberration variation over the entire zoom range and the entire focus range, it is often necessary to increase the number of lenses in each lens group to increase the degree of freedom in aberration correction. Will be. Therefore, if an attempt is made to achieve a zoom lens with a large aperture ratio and a high zoom ratio, the number of lenses will inevitably increase, and the size of the entire lens system will increase.

If the inner focus method, which is one of the focusing methods, is adopted, the entire lens system can be downsized, quick focusing can be performed, and close-up photography can be facilitated as described above. To be

However, the variation of aberration at the time of half-focusing, especially the variation of spherical aberration at the telephoto end becomes large,
There is a problem that it becomes very difficult to obtain high optical performance while miniaturizing the entire lens system over the entire object distance from an infinite object to a short-distance object.

For example, the focusing system proposed in Japanese Patent Publication No. 52-41068 mentioned above does not always have a sufficient lens structure for a zoom lens for broadcasting which requires a large aperture ratio, a high zoom ratio, a short MOD and high specifications. There wasn't. In particular,
The distribution of refractive power between the focusing lens group and the fixed lens group of the first group, the dispersion value of the material of each lens, and the like are not always sufficient for a broadcast zoom lens with high specifications.

In general, it is necessary to appropriately set the refracting power and the lens configuration of each lens group in order to achieve high specifications while achieving downsizing and weight reduction of the entire zoom lens, which has been generally desired by users in recent years. Particularly in a four-group zoom lens, the refractive power and the brightness of the lens group, which are shared by the first group (front lens group) that most influences the size and weight of the entire lens system, are important factors.
How to balance the whole zoom lens system is an important factor.

Furthermore, in order to obtain high optical performance over the entire focus range, it is necessary to suppress aberration fluctuation due to focus. Of these, it is impossible to obtain a good image unless the fluctuations of spherical aberration and chromatic aberration, which have the largest fluctuation due to focusing, are suppressed as much as possible. For this reason, what kind of aberration and achromatism should be shared between the focusing lens group and the fixed lens group is an important factor.

The present invention relates to a so-called four-group zoom lens,
After properly setting the refractive power and F number of the front lens group (first group), the front lens group is divided into two lens groups, a focusing lens group and a fixed lens group, and aberration fluctuations due to focusing By stipulating the lens element layout, aberration sharing, and achromatization sharing to satisfy the specified conditions, the fluctuations of spherical aberration and chromatic aberration due to zooming and focusing can be reduced, and zooming can be further reduced. Astigmatism, off-axis aberrations such as curvature of field, etc., are corrected in a well-balanced manner, and the wide-angle end has an F number of approximately 1.6 with high optical performance over the entire zoom range and focus range. An object is to provide a zoom lens having a large aperture ratio of about 14 to 44 and a high zoom ratio.

[0018]

A zoom lens according to the present invention includes, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power for zooming, and an image plane variation due to zooming. Third to correct
In a zoom lens having a group, and a fourth group having a fixed image-forming action during zooming, the first group includes an 11th group that is fixed during focusing and an object when focusing from an infinite object to a close object. And a twelfth lens unit moving to the side, the eleventh lens unit including at least one negative lens LN11 and at least one positive lens LN11.
N12 has two independent lenses, the twelfth lens group has at least two positive lenses, and the focal length and F number of the entire system at the telephoto end are fT and FNT, respectively, and the focal point of the first lens group. When the distance and the F number are f1 and FN1, the focal lengths of the 11th group and the 12th group are f11 and f12, respectively, and the Abbe number difference between the materials of the negative lens LN11 and the positive lens LP12 is ΔνX, 1.04 <FN1 <1.55 However, FN1 = f1 / (fT / FNT) ... (1) 0.28 <f1 / fT <0.80 ..... ... (2) 55 <ΔνX ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (3) 3 <│f11 / f1│・ ・ ・ ・ ・ ・ ・ ・ ・ (4) 0.77 <f12 / f1 <1.10 ・ ・ ・ ・ ・ ・ (5) It is characterized by satisfying the conditions.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1, 2, 3 and 4 are lens cross-sectional views at the wide-angle end of Numerical Embodiments 1, 2, 3 and 4 of the present invention, respectively. 5 to 7 are aberration diagrams of Numerical Example 1 of the present invention, FIGS. 8 to 12 are aberration diagrams of Numerical Example 2 of the present invention, and FIGS.
FIG. 17 is an aberration diagram of Numerical Example 3 of the present invention, and FIGS.
2 is an aberration diagram of Numerical example 4 of the present invention.

In FIGS. 1 to 4, F is a lens group (front lens group) having a positive refracting power as the first group, which is a fixed eleventh group F11 and a twelfth lens having a positive refracting power for focusing. It is composed of two lens groups of the group F12. 11th group F1
1 has two independent lenses, at least one negative lens LN11 and at least one positive lens LP12. The twelfth lens unit F12 has at least two positive lenses. Focusing from an object at infinity to an object at a close range is performed by moving the twelfth lens unit F12 toward the object side.

V is a variator of negative refracting power for zooming as the second lens unit, which is monotonically moved to the image plane side on the optical axis to change from the wide-angle end (wide) to the telephoto end (tele). We are changing the magnification. In the second group V, the image-forming magnification is changed within a region including a unity magnification (−1 ×) when the magnification is changed.

C is a compensator having a positive or negative refractive power as the third lens unit, and is moved to correct the image plane variation due to zooming. SP is a stop and R is a relay group having a positive refractive power as the fourth group. G is a color separation prism, an optical filter or the like, which is shown as a glass block in FIG.

Generally, in the so-called front lens focus system, in which focusing is performed on the entire first group closest to the object side in the four-group zoom lens, the amount of extension of the first group is constant for the same object distance at each focal length. Therefore, the lens barrel structure is simple.

However, the first group has a positive refractive power,
In a zoom lens including a wide angle of view, when focusing on a close-range object at the wide-angle end, the first group moves toward the object side, so that the effective diameter of the first group increases to secure an off-axis light beam, Further, since the relatively heavy first group is moved, the driving torque increases, and quick focusing becomes difficult.

Therefore, in the present invention, in the zoom lens having the above-mentioned structure and satisfying the conditional expression, the focusing from the object at infinity to the object at the close range is performed by the twelfth lens unit F1.
By adopting an inner focus method in which 2 is moved to the object side, the effective lens diameter of the first lens unit F is prevented from increasing, the overall lens system is downsized, and the closest distance is further shortened. .

Particularly, the zoom lens of the present invention has a magnification of 14 to 4 times.
In order to have a zoom ratio of about 4 times and to realize a large aperture in the entire zoom range, first, a front lens group (first group) F is provided with a bright lens system that satisfies the conditional expression (1). I am using. Then, the refractive power of the front lens group F is made to satisfy the conditional expression (2), thereby making it compact.

Then, the variator V is adapted to pass a point where the image forming magnification is -1 × (equal magnification) during zooming, thereby adopting a zoom system which has a high variable magnification. Further, the compensator C has a positive or negative refractive power, and by arranging at least one positive lens and a negative lens, aberration correction such as spherical aberration and chromatic aberration is enhanced.

When the zoom lens of the present invention is used for a television camera for broadcasting, for example, high specifications and high performance are required. Above all, a long focal length and a large aperture at the telephoto end are required.

Generally, in a so-called four-group zoom lens, if an attempt is made to increase the focal length and the aperture at the telephoto end, the effective aperture of the front lens group remarkably increases. This is because the incident height of the axial ray increases, which causes various aberrations such as spherical aberration and chromatic aberration due to zooming and focusing, and it becomes difficult to correct these aberrations.

On the other hand, if the number of lenses is increased to increase the degree of freedom in design, the entire lens system becomes large and the weight and manufacturing cost increase.

Therefore, in this embodiment, the front lens group (first group) is arranged in order from the object side, the eleventh group which is always stationary with respect to a given object point, a so-called focus fixed group F11, and a light beam. It is composed of a twelfth group, which is a so-called focus moving group F12, which performs focusing by relatively moving on the axis.

Further, the focus fixing group F11 is arranged in order from the object side with at least one negative lens LN11 and at least one positive lens LP1 with a relatively small air gap.
It is composed of 2 and.

In this fixed focus group F11,
The difference ΔνX between the Abbe numbers of the materials of the negative lens LN11 and the positive lens LP12 is set as in conditional expression (3). As a result, variations in chromatic aberration due to zooming or focusing are well corrected.

In addition, the negative lens LN11 and the positive lens LP
12 is not used as a cemented lens, and is arranged with a relatively small air gap. A space formed by the radius of curvature of the image-side lens surface of the negative lens LN11 and the radius of curvature of the object-side lens surface of the positive lens LP12 that sandwich the air space, that is, a so-called air lens has a substantially equal radius of curvature or a convex shape toward the object side. It is configured in a positive meniscus lens shape.

By constructing this air lens, (a) the degree of freedom in design is increased, and the burden of aberration correction is reduced. (B) Since each aberration can be sharply adjusted, high-order aberrations in particular (C) Since the negative lens LN11 is separated, the principal point of the front lens group is pushed out, which contributes to size reduction.

Further, the focal length f of the fixed focus group F11
11 is set as the conditional expression (4) with respect to the focal length f1 of the front lens group F. This is the fixed focus group F
It is shown that the focal length f11 of 11 has a considerably small refractive power regardless of the sign of the absolute value in terms of paraxial power arrangement.
However, the lower limit is determined when the absolute value of the refractive power is negative. This is one way to reduce the size of the entire zoom lens system while widening the angle. As a result, the power of the front lens group F may be increased to obtain the lateral magnification of the entire zoom lens system.

At this time, the refractive power of each lens element F of the front lens group also becomes strong, but the divergence of the focus fixing group F11 is strengthened by adopting the above-mentioned air lens, and even if a so-called retro ratio is increased, it becomes aberrated. It stabilizes at a high level. However, if the lens has extreme divergence, it becomes difficult to correct aberrations in other lens elements, so the range of conditional expression (4) is limited.

The sign of the focal length is not limited to positive or negative, even if the focal length of the fixed focus group F11 is positive and the spherical aberration share value at the telephoto end of the fixed focus group F11 is negative. This is because the axial light flux after passing through the focus fixing group F11 has divergence.

Further, the focus movement group F12 has at least two positive lenses, and various aberrations such as spherical aberration, astigmatism and distortion are obtained in order to obtain high optical performance corresponding to high zooming and short MOD. It is configured with the minimum necessary degree of design freedom to correct variations in aberration. The focal length f12 of the focus movement group F12 is set as in conditional expression (5).

The focal length f12 of the focus movement group F12
Becomes larger, the feeding amount due to the focusing action increases.
Therefore, the dead space in the front lens group F increases, and the size of the front lens group that influences the size and weight of the zoom lens increases. On the other hand, when the focal length f12 of the focus moving group F12 becomes smaller, the front lens group as a whole can be downsized, but the radius of curvature of each lens element of the focus moving group F12 becomes sharply smaller, so that aberrations due to zooming and focusing occur. It becomes difficult to correct the fluctuation.

Therefore, it is necessary to limit the focal length f12 of the focus moving unit F12 in consideration of the balance between optical performance and miniaturization. In a zoom lens that requires high optical performance such as a zoom lens for broadcasting, the optical performance cannot be lowered due to an unreasonable downsizing, so that the conditional expression (5) is limited. A negative lens may be used in the focus movement group F12 to cancel various aberrations.

In this embodiment, the optical arrangement of the front lens group F and the limiting conditions are determined as described above. By satisfying these optical arrangements and limiting conditions, a so-called floating effect can be obtained.

Here, the term "floating" means that the angle at which a light beam passes is expanded or contracted by expanding or contracting an arbitrary air interval in the lens group that moves when the object distance changes and the object is in focus. The height is changed to suppress variation in aberration. For this reason, it is desirable that the interval used for floating is such that the angle at which light rays pass is divergent or convergent.

In this embodiment, a lens having negative refracting power is arranged on the most object side of the front lens group F, and an air lens is adopted, so that the principal point of the whole front lens group F becomes the image side. Focus fixed group F1
The axial ray after passing 1 is divergent from the point of the aberration correction sharing value.

In the present invention, in consideration of aberration variation due to focusing at the telephoto end, a fixed focus group is provided in order to favorably correct spherical aberration and axial chromatic aberration, which are greatly varied due to an increase in axial ray incident height. It is preferable to satisfy the following conditional expression in the aberration sharing value of F11 and the focus movement group F12.

The sum of the third-order aberration coefficients of the spherical aberrations of the lens surfaces of the 11th and 12th lens groups at the telephoto end is S, respectively.
When S1 and S2 are set, the open F number is used over the entire focus range.

[0047]

[Equation 2] To satisfy the condition. Further, the focal length of the i-th lens of the 11th group and the Abbe number of the material are respectively f
11i, ν11i, and the Abbe number of the material and the focal length of the i-th lens of the 12th group are f12i, ν12i,

[0048]

[Equation 3] To satisfy the condition.

In the conditional expression (6) relating to the third-order aberration coefficient of the spherical aberration, the divergent spherical aberration is generated in the focus fixed group F11 and the focus movement group F is generated for the reason described above.
12 shows that a convergent spherical aberration is generated. Then, the respective amounts of occurrence are controlled so as not to be over- or under-corrected, and good aberration correction is performed.

Conditional expressions (7) to (8) are so-called achromatic conditions. The focal lengths f11 and f1 of each lens element of the focus fixed group F11 and the focus movement group F12
2 and Abbe's number are controlled so that EF≈EM≈0, which is the solution of the achromatic condition, is satisfied. Further, the conditional expression (9) is for making the sharing of the focus fixed group F11 and the focus moving group F12 substantially equal.

As described above, in this embodiment, the front lens group F
Is composed of a focus fixed group F11 and a focus moving group F12, and by appropriately setting the power arrangement, the material of the lens element, and the distribution of aberrations, various aberrations in the entire zoom range and the entire focus range, particularly spherical aberration and axial chromatic aberration, are excellent. Has been corrected to.

Next, numerical examples of the present invention will be shown. In the numerical examples, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air gap from the object side, and Ni and νi are respectively from the object side in the i-th lens. The refractive index of glass and the Abbe number. In the numerical examples, the last two or three lens surfaces are glass blocks such as face plates and filters.

Table 1 shows the relationship between the above-mentioned conditional expressions and various numerical values in the numerical examples.

The aspherical shape has an X axis in the optical axis direction, an H axis in the direction perpendicular to the optical axis, a positive traveling direction of light, and R is a paraxial radius of curvature,
When K, A ₂ , A ₃ , A ₄ , and A ₅ are aspherical coefficients,

[0055]

[Equation 4] It is expressed by

Further, the third-order aberration coefficients of the axial chromatic aberration and spherical aberration of each lens surface at the telephoto end in each numerical example will be shown.

Numerical Example 1 F = 11.27 FNO = 1: 1.6 to 1.8 2ω = 52.0 ° to 3.7 ° R 1 = 3554.41 D 1 = 3.09 N 1 = 1.87400 ν 1 = 35.3 R 2 = 152.88 D 2 = 1.57 R 3 = 172.06 D 3 = 15.39 N 2 = 1.43875 ν 2 = 95.0 R 4 = -278.47 D 4 = 14.04 R 5 = 160.87 D 5 = 13.76 N 3 = 1.49700 ν 3 = 81.6 R 6 = -336.03 D 6 = 0.21 R 7 = 86.37 D 7 = 11.25 N 4 = 1.51633 ν 4 = 64.2 R 8 = 225.21 D 8 = Variable R 9 = 70.95 D 9 = 1.65 N 5 = 1.77250 ν 5 = 49.6 R10 = 29.20 D10 = 6.76 R11 = -2104.50 D11 = 1.51 N 6 = 1.77250 ν 6 = 49.6 R12 = 59.82 D12 = 8.57 R13 = -32.42 D13 = 1.51 N 7 = 1.77250 ν 7 = 49.6 R14 = 345.76 D14 = 4.32 N 8 = 1.92286 ν 8 = 21.3 R15 = -65.28 D15 = Variable R16 = -535.12 D16 = 6.13 N 9 = 1.48749 ν 9 = 70.2 R17 = -50.92 D17 = 0.21 R18 = 263.61 D18 = 8.55 N10 = 1.64000 ν10 = 60.1 R19 = -47.42 D19 = 1.65 N11 = 1.80518 ν11 = 25.4 R20 = -147.42 D20 = 0.21 R21 = 53.82 D21 = 7.03 N12 = 1.48749 ν12 = 70.2 R22 = -646.25 D22 = Variable R23 = (Aperture) D23 = 4.10 R24 = -34.54 D24 = 0.96 N13 = 1.65160 ν13 = 58.5 R25 = 24.78 D25 = 3.36 N14 = 1.69895 ν14 = 30.1 R26 = 49.32 D26 = 6.58 R27 = -2 9.97 D27 = 1.03 N15 = 1.64000 ν15 = 60.1 R28 = -2416.74 D28 = 6.00 N16 = 1.68893 ν16 = 31.1 R29 = -27.45 D29 = 23.38 R30 = 101.35 D30 = 8.48 N17 = 1.48749 ν17 = 70.2 R31 = -28.60 D31 = 1.51 N18 = 1.75520 ν18 = 27.5 R32 = -38.07 D32 = 0.14 R33 = 175.76 D33 = 1.31 N19 = 1.75520 ν19 = 27.5 R34 = 27.12 D34 = 6.72 N20 = 1.51118 ν20 = 51.0 R35 = -276.56 D35 = 0.76 R36 = 43.76 D36 = 3.99 N21 = 1.48749 ν21 = 70.2 R37 = 0.00 D37 = 5.70 R38 = 0.00 D38 = 47.57 N22 = 1.51633 ν22 = 64.2 R39 = 0.00

[0058]

[Table 1] Third-order aberration coefficient at the telephoto end Surface-sharing value (Numerical Example 1) Axial chromatic aberration Spherical aberration Surface number Infinity Near infinity Near infinity 1 0.012 0.049 0.000 0.052 2 -0.519 -0.666 -58.015 -103.794 3 0.114 0.147 38.260 68.955 4 0.025 0.023 0.064 -0.073 5 0.105 0.136 10.150 20.028 6 0.087 0.095 8.782 8.915 7 0.145 0.190 3.775 9.977 8 0.051 0.049 2.430 1.926 9 -0.023 -0.023 -0.510 -0.510 10 -0.108 -0.108 -5.327 -5.327 11 -0.020 -0.020- 0.155 -0.155 12 -0.084 -0.084 -6.331 -6.331 13 -0.092 -0.092 -2.098 -2.098 14 0.258 0.258 3.172 3.172 15 0.018 0.018 -0.027 -0.027 16 0.030 0.030 2.198 2.198 17 0.045 0.045 1.530 1.530 18 0.031 0.031 0.615 0.615 19- 0.261 -0.261 -3.219 -3.219 20 0.087 0.087 0.320 0.320 21 0.054 0.054 3.945 3.945 22 0.033 0.033 2.404 2.404 23 0.000 0.000 0.000 0.000 24 -0.054 -0.054 -9.394 -9.394 25 0.081 0.081 0.515 0.515 26 -0.071 -0.071 -2.136 -2.136 27 -0.027 -0.027 -0.226 -0.226 28 0.042 0.042 0.155 0.155 29 0.109 0.109 3.278 3.278 30 0.014 0.014 0.273 0.273 31 -0.167 -0.167 -4.786 -4.786 32 0.169 0.169 11.532 11.532 33 -0.031 -0.031 -0.189 -0.189 34 -0.117 -0.117 -2.049 -2.049 35 0.022 0.022 0.552 0.552 36 0.012 0.012 -0.047 -0.047 37 0.021 0.021 2.092 2.092 38- 0.021 -0.021 -1.872 -1.872 39 0.003 0.003 0.300 0.300 Total -0.021 -0.018 -0.037 0.502 (Numerical example 2) F = 9.0 FNO = 1: 1.7 to 2.0 2 ω = 62.9 ° to 5.0 ° R 1 = -409.82 D 1 = 2.50 N 1 = 1.76168 ν 1 = 27.5 R 2 = 131.70 D 2 = 3.86 R 3 = 226.86 D 3 = 7.89 N 2 = 1.43985 ν 2 = 95.0 R 4 = -210.28 D 4 = 0.20 R 5 = 185.11 D 5 = 6.65 N 3 = 1.43985 ν 3 = 95.0 R 6 = -432.14 D 6 = 7.25 R 7 = 97.28 D 7 = 9.98 N 4 = 1.49845 ν 4 = 81.6 R 8 = -296.46 D 8 = 0.20 R 9 = 58.15 D 9 = 5.98 N 5 = 1.73234 ν 5 = 54.7 R10 = 116.22 D10 = Variable R11 = 82.50 D11 = 0.80 N 6 = 1.88814 ν 6 = 40.8 R12 = 16.69 D12 = 4.85 R13 = -60.39 D13 = 0.80 N 7 = 1.82017 ν 7 = 46.6 R14 = 44.25 D14 = 2.55 R15 = 29.50 D15 = 4.52 N 8 = 1.82600 ν 8 = 23.7 R16 = -51.57 D16 = 0.94 R17 = -30.92 D17 = 0.80 N 9 = 1.77621 ν 9 = 49.6 R18 = 123.22 D18 = variable R19 = -28.08 D19 = 0.90 N10 = 1.76077 ν10 = 47.8 R20 = 44.63 D20 = 2.37 N11 = 1.85501 ν11 = 23.9 R21 = -788.03 D21 = Variable R22 = (Aperture) D22 = 1.10 R23 = 219.42 D23 = 3.26 N12 = 1.70558 ν12 = 41.2 R24 = -59.63 D24 = 0.20 R25 = 126.00 D25 = 2.15 N13 = 1.50349 ν13 = 56.4 R26 = 1747.85 D26 = 0.20 R27 = 86.13 D27 = 6.25 N14 = 1.50349 ν14 = 56.4 R28 = -26.00 D28 = 1.30 N15 = 1.80811 ν15 = 46.6 R29 = -71.32 D29 = 28.00 R30 = 58.16 D30 = 6.02 N16 = 1.48915 ν16 = 70.2 R31 = -41.51 D31 = 0.20 R32 = -85.39 D32 = 1.40 N17 = 1.83932 ν17 = 37.2 R33 = 33.66 D33 = 6.06 N18 = 1.50014 ν18 = 65.0 R34 = -118.13 D34 = 0.20 R35 = 70.99 D35 = 6.52 N19 = 1.48915 ν19 = 70.2 R36 = -26.37 D36 = 1.40 N20 = 1.83945 ν20 = 42.7 R37 = -72.54 D37 = 0.20 R38 = 46.43 D38 = 4.12 N21 = 1.60548 ν21 = 60.7 R39 = -350.11 D39 = 4.10 R40 = ∞ D40 = 30.00 N22 = 1.60718 ν22 = 38.0 R41 = ∞ D41 = 16.20 N23 = 1.51825 ν23 = 64.2 R42 = ∞

[0059]

[Table 2] Third-order aberration coefficient at the telephoto end Surface-sharing value (Numerical Example 2) Axial chromatic aberration Spherical aberration Surface number Infinity close-up Infinity close-up 1 -0.072 -0.039 -0.099 0.012 2 -0.454 -0.557 -46.209 -77.776 3 0.070 0.088 21.231 37.794 4 0.009 0.003 -0.055 -0.011 5 0.054 0.071 7.519 15.386 6 0.015 0.010 0.130 0.002 7 0.081 0.106 8.099 17.434 8 0.079 0.084 16.499 16.130 9 0.143 0.191 -1.853 0.972 10 0.078 0.075 7.369 5.930 11 -0.064 -0.064 -8.835 -8.835 12 -0.083 -0.083 -3.798 -3.798 13 -0.032 -0.032 -1.019 -1.019 14 -0.056 -0.056 -6.414 -6.414 15 0.163 0.163 13.088 13.088 16 0.119 0.119 6.170 6.170 17 -0.064 -0.064 -11.356 11.356 18 -0.019 -0.019 -0.325 -0.325 19 -0.036 -0.036 -0.477 -0.477 20 0.129 0.129 1.881 1.881 21 -0.097 -0.097 -4.076 -4.076 22 0.000 0.000 0.000 0.000 23 0.062 0.062 6.340 6.340 24 0.009 0.009 -0.031 -0.031 25 0.024 0.024 1.229 1.229 26 -0.010 -0.010 -0.138 -0.138 27 0.024 0.024 1.079 1.079 28 -0.043 -0.043 -4.042 -4.042 29 0.024 0.024 0.093 0.093 30 0.022 0.022 1. 076 1.076 31 0.045 0.045 13.382 13.382 32 -0.088 -0.088 -6.783 -6.783 33 -0.082 -0.082 -3.355 -3.355 34 0.012 0.012 0.188 0.188 35 0.012 0.012 0.119 0.119 36 -0.090 -0.090 -9.930 -9.930 37 0.051 0.051 1.813 1.813 38 0.018 0.018 0.011 0.011 39 0.031 0.031 3.712 3.712 40 -0.043 -0.043 -2.559 -2.559 41 0.010 0.010 0.098 0.098 42 0.004 0.004 0.519 0.519 Total -0.036 -0.010 0.294 3.537 (Numerical Example 3) F = 8.50 FNO = 1: 1.7 ~ 2.1 2 ω = 65.8 ° ~ 4.9 ° R 1 = -243.48 D 1 = 2.50 N 1 = 1.81265 ν 1 = 25.4 R 2 = 150.43 D 2 = 3.13 R 3 = 229.76 D 3 = 7.86 N 2 = 1.43985 ν 2 = 95.0 R 4 = -215.69 D 4 = 7.33 R 5 = 165.25 D 5 = 10.30 N 3 = 1.43985 ν 3 = 95.0 R 6 = -156.97 D 6 = 0.15 R 7 = 91.92 D 7 = 8.25 N 4 = 1.60520 ν 4 = 65.5 R 8 = -5448.23 D 8 = 0.15 R 9 = 53.54 D 9 = 5.38 N 5 = 1.77621 ν 5 = 49.6 R10 = 88.04 D10 = Variable R11 = 51.26 D11 = 0.90 N 6 = 1.88814 ν 6 = 40.8 R12 = 16.17 D12 = 4.80 R13 = -63.80 D13 = 0.80 N 7 = 1.82017 ν 7 = 46.6 R14 = 27.55 D14 = 4.03 R15 = 27.93 D15 = 4.20 N 8 = 1.82600 ν 8 = 23.7 R16 = -54.11 D16 = 0.75 R17 = -30.5 2 D17 = 0.80 N 9 = 1.77621 ν 9 = 49.6 R18 = 124.76 D18 = variable R19 = -26.78 D19 = 0.90 N10 = 1.77621 ν10 = 49.6 R20 = 45.15 D20 = 2.47 N11 = 1.85501 ν11 = 23.9 R21 = -318.46 D21 = variable R22 = (Aperture) D22 = 1.10 R23 = 177.68 D23 = 3.91 N12 = 1.51977 ν12 = 52.4 R24 = -42.08 D24 = 0.20 R25 = 112.64 D25 = 2.72 N13 = 1.51977 ν13 = 52.4 R26 = -179.30 D26 = 0.20 R27 = 69.16 D27 = 6.04 N14 = 1.51977 ν14 = 52.4 R28 = -31.66 D28 = 1.30 N15 = 1.82017 ν15 = 46.6 R29 = -206.87 D29 = 32.00 R30 = 65.05 D30 = 5.69 N16 = 1.48915 ν16 = 70.2 R31 = -41.40 D31 = 0.20 R32 =- 82.84 D32 = 1.40 N17 = 1.83932 ν17 = 37.2 R33 = 30.46 D33 = 5.78 N18 = 1.50349 ν18 = 56.4 R34 = -300.07 D34 = 0.20 R35 = 63.06 D35 = 6.80 N19 = 1.48915 ν19 = 70.2 R36 = -25.89 D36 = 1.40 N20 = 1.83932 ν20 = 37.2 R37 = -57.77 D37 = 0.20 R38 = 36.55 D38 = 4.53 N21 = 1.51314 ν21 = 60.5 R39 = -607.99 D39 = 4.00 R40 = ∞ D40 = 30.00 N22 = 1.60718 ν22 = 38.0 R41 = ∞ D41 = 16.20 N23 = 1.51825 ν23 = 64.2 R42 = ∞

[0060]

[Table 3] Third-order aberration coefficient at the telephoto end Surface-sharing value (Numerical example 3) Axial chromatic aberration Spherical aberration Surface number Infinity close-up Infinity close-up 1 -0.149 -0.124 -0.532 -0.053 2 -0.563 -0.732 -57.708 -108.482 3 0.083 0.110 30.951 60.323 4 0.002 -0.006 -0.005 -0.063 5 0.075 0.098 16.590 33.061 6 0.057 0.058 5.724 4.101 7 0.130 0.172 7.740 19.117 8 0.106 0.109 15.147 13.563 9 0.200 0.269 -4.761 -1.964 10 0.073 0.059 4.578 2.652 11 -0.066 -0.066- 8.751 -8.751 12 -0.082 -0.082 -1.137 -1.137 13 -0.044 -0.044 -3.084 -3.084 14 -0.076 -0.076 -13.151 -13.151 15 0.186 0.186 16.297 16.297 16 0.132 0.132 7.221 7.221 17 -0.073 -0.073 -14.200 -14.200 18 -0.020 -0.020 -0.318 -0.318 19 -0.042 -0.042 -0.823 -0.823 20 0.149 0.149 1.897 1.897 21 -0.100 -0.100 -4.002 -4.002 22 0.000 0.000 0.000 0.000 23 0.045 0.045 6.846 6.846 24 0.018 0.018 -0.073 -0.073 25 0.030 0.030 1.540 1.540 26 0.003 0.003 -0.001 -0.001 27 0.028 0.028 0.833 0.833 28 -0.038 -0.038 -4.097 -4.097 29 0.007 0.007 0.000 0.000 30 0.019 0. 019 0.664 0.664 31 0.047 0.047 13.659 13.659 32 -0.093 -0.093 -7.109 -7.109 33 -0.084 -0.084 -4.957 -4.957 34 0.002 0.002 -0.000 -0.000 35 0.019 0.019 0.639 0.639 36 -0.121 -0.121 -9.366 -9.366 37 0.074 0.074 2.791 2.791 38 0.025 0.025 0.324 0.324 39 0.029 0.029 3.230 3.230 40 -0.045 -0.045 -2.709 -2.709 41 0.011 0.011 0.103 0.103 42 0.005 0.005 0.549 0.549 Total -0.036 -0.039 0.541 5.072 (Numerical Example 4) F = 14.0 FNO = 1 : 2.45 ~ 4.2 2 ω = 42.9 ° ~ 1.0 ° R 1 = 412.92 D 1 = 5.50 N 1 = 1.85649 ν 1 = 32.3 R 2 = 185.82 D 2 = 0.25 R 3 = 185.28 D 3 = 19.08 N 2 = 1.43985 ν 2 = 95.0 R 4 = -3890.59 D 4 = 9.93 R 5 = 210.59 D 5 = 14.55 N 3 = 1.43985 ν 3 = 95.0 R 6 = 4882.30 D 6 = 0.20 R 7 = 189.41 D 7 = 12.65 N 4 = 1.45720 ν 4 = 90.3 R 8 = 849.12 D 8 = 0.20 R 9 = 184.77 D 9 = 9.56 N 5 = 1.49845 ν 5 = 81.6 R10 = 450.59 D10 = Variable R11 = 1978.17 D11 = 2.00 N 6 = 1.82017 ν 6 = 46.6 R12 = 61.00 D12 = 4.30 R13 = -244.81 D13 = 1.80 N 7 = 1.77621 ν 7 = 49.6 R14 = 49.97 D14 = 7.53 R15 = -56.56 D15 = 1.80 N 8 = 1.82017 ν 8 = 46.6 R16 = 48.78 D16 = 7.7 1 N 9 = 1.93306 ν 9 = 21.3 R17 = -227.11 D17 = Variable R18 = 1717.21 D18 = 6.39 N10 = 1.49845 ν10 = 81.6 R19 = -106.26 D19 = 0.30 R20 = 200.29 D20 = 2.50 N11 = 1.65223 ν11 = 33.8 R21 = 72.78 D21 = 12.98 N12 = 1.59143 ν12 = 61.2 R22 = -125.34 D22 = 0.20 R23 = 107.54 D23 = 13.87 N13 = 1.62032 ν13 = 63.4 R24 = -71.24 D24 = 2.50 N14 = 1.85501 ν14 = 23.9 R25 = -196.04 D25 = 0.20 R26 = 124.29 D26 = 3.50 N15 = 1.48915 ν15 = 70.2 R27 = 221.46 D27 = Variable R28 = (Aperture) D28 = 2.89 R29 = -54.75 D29 = 1.80 N16 = 1.79013 ν16 = 44.2 R30 = 37.11 D30 = 4.93 N17 = 1.81265 ν17 = 25.4 R31 = 202.88 D31 = 6.91 R32 = -53.04 D32 = 1.60 N18 = 1.73234 ν18 = 54.7 R33 = 34.16 D33 = 7.84 N19 = 1.59911 ν19 = 39.2 R34 = -35.88 D34 = 20.00 R35 = 365.53 D35 = 4.61 N20 = 1.48915 ν20 = 70.2 R36 = -35.90 D36 = 0.20 R37 = -61.03 D37 = 2.20 N21 = 1.79013 ν21 = 44.2 R38 = 34.15 D38 = 5.94 N22 = 1.50349 ν22 = 56.4 R39 = -46.65 D39 = 1.10 R40 = 556.89 D40 = 4.36 N23 = 1.55099 ν23 = 45.8 R41 = -46.17 D41 = 2.20 N24 = 1.81265 ν24 = 25.4 R42 = -177.20 D42 = 0.20 R43 = -2240.85 D43 = 2.70 N25 = 1.51977 ν25 = 52.4 R44 = -64.85 D44 = 5.00 R45 = ∞ D45 = 50.00 N26 = 1.51825 ν26 = 64.2 R46 = ∞

[0061]

[Table 4] Aspherical shape Reference spherical surface R = 124.297 Aspherical surface coefficient A = B = C = E = 0 D = 5.99704 × 10 ⁻¹⁴ Third-order aberration coefficient at telephoto end Surface sharing value (Numerical example 4) Axial chromatic aberration Spherical aberration Face number Infinity Near infinity Near infinity 1 0.990 1.200 36.300 69.827 2 -3.192 -3.612 -1960.567 -2661.373 3 0.674 0.763 1544.973 2088.964 4 0.019 -0.003 0.018 -0.001 5 0.409 0.475 237.855 364.404 6 0.148 0.139 30.266 22.897 7 0.289 8347 7.323 31.451 0.235 0.235 125.596 115.001 9 0.129 0.176 -15.177 -23.649 10 0.329 0.336 262.290 256.185 11 -0.321 -0.321 -241.207 -241.207 12 -0.076 -0.076 2.940 2.940 13 -0.170 -0.170 -44.639 -44.639 14 -0.300 -0.300 -160.407 -160.407 15 -0.143 -0.143 1.602 1.602 16 1.260 1.260 131.823 131.823 17 -0.368 -0.368 -26.757 -26.757 18 0.096 0.096 58.123 58.123 19 0.016 0.016 -0.451 -0.451 20 0.296 0.296 47.621 47.621 21 -0.331 -0.331 -17.547 -17.547 22 0.103 0.103 7.740 7.740 23 0.119 0.119 12.091 12.091 24 -0.831 -0.831 -65.869 -65.869 25 0.493 0.493 49.542 49.542 26 0.007 0.007 -0.083 -0.083 27 0.039 0.039 4.135 4.135 28 0.000 0.000 0.000 0.000 29 -0.130 -0.130 -45.232 -45.232 30 0.111 0.111 0.286 0.286 31 -0.002 -0.002 0.000 0.000 32 -0.050 -0.050 -4.651 -4.651 33 0.037 0.037 -8.489 -8.489 34 0.103 0.103 14.155 14.155 35 -0.002 -0.002 -0.009 -0.009 36 0.056 0.056 36.830 36.830 37 -0.095 -0.095 -21.901 -21.901 38 -0.048 -0.048 -5.136 -5.136 39 0.047 0.047 8.852 8.852 40 -0.015 -0.015- 0.279 -0.279 41 -0.115 -0.115 -4.543 -4.543 42 0.068 0.068 1.513 1.513 43 -0.015 -0.015 -0.461 -0.461 44 0.049 0.049 10.579 10.579 45 -0.019 -0.019 -2.062 -2.062 46 0.006 0.006 0.731 0.731 Total -0.093 -0.068 7.720 2.547

[0062]

[Table 5] Next, features of each numerical example of the present invention will be described.

Numerical Embodiment 1 shown in FIG. 1 has a zoom ratio of more than 15 times, and R1 to R8 are the front lens group F (focus group F). Of these, R1-R4 are zooming,
It is a fixed focus group F11 that is fixed during focusing and has a negative power (refractive power) as a whole. R5-R
The focus moving group F12 has a positive power. R
1 to R8 function as the front lens group F having the function of connecting the object points to the variator V, and the whole front lens group F has a positive power.

R9 to R15 mainly contribute to zooming, and when zooming from wide to tele, the variator V monotonously moves to the image plane side and passes the imaging magnification of -1 (equal magnification) on the way. Is. R16 to R22 are compensators C, which mainly have an image point correcting action associated with zooming and also have a zooming action.
The compensator C has a positive power, and monotonously moves from the wide-angle end reference position to the object side during zooming from wide to tele. SP (R23) is a diaphragm.

R24 to R37 are a relay group R having an image forming action, and R38 to R39 are glass blocks equivalent to color separation prisms.

When the F number of the front lens group is defined as FN1 = f1 (fT / FNT) as an index for increasing the aperture, FN1 = 1.416 in this embodiment. In addition, the power distribution of the front lens group is f1 / fT as an index of downsizing.
Then, in this embodiment, it becomes 0.785.

For the large aperture and power sharing, the front lens group has one negative lens and one positive lens in the fixed focus group in order to correct spherical aberration and axial chromatic aberration.
Two positive lenses are used by the focus moving group to perform correction.

In general, it is preferable that the lens configuration of the front lens group F be as simple as possible and that the block thickness be small in order to reduce the size of the entire zoom system and to save power in the drive system. For this reason, it is desirable to reduce the number of lenses in the front lens group F as much as possible.

On the other hand, as described above, the F number FN1 of the front lens group becomes extremely bright, and the power distribution of the front lens is also strong, so that spherical aberration due to zooming, focusing, and axial chromatic aberration. It will be difficult to correct such problems.

Therefore, in this embodiment, a negative lens having a very high refractive index is used as the eleventh lens of the focus fixed group, and a positive lens having a very high Abbe number is used as the twelfth lens of the focus fixed group. This suppresses the occurrence of spherical aberration and axial chromatic aberration. At this time, the difference between the Abbe numbers of the materials of the focus fixing group is ΔνX = 59.7.

At this time, the assigned values of the fixed focus group and the focused movement group are the spherical aberration at the telephoto end (in the entire focus area) −0.853 ≦ S1 / S2 ≦ −0.783 Achromatic contribution EF / EM = −0. It is 979.

Numerical embodiment 2 shown in FIG. 2 has a zoom ratio of more than 14 times, and R1 to R10 are the front lens group F (focus group F). Of these, R1 to R6 are fixed during zooming and focusing, and are a fixed focus group F11 having a positive power (refractive power) as a whole.
7 to R10 have positive power in the focus movement group F12. The front lens group F having the function of connecting the object points to the variator V by R1 to R10 functions, and the front lens group F as a whole has a positive power.

R11 to R18 mainly contribute to zooming, and are a variator V that moves monotonically toward the image plane side when zooming from wide to tele, and passes an imaging magnification of -1 (one-time magnification) on the way. is there. R19 to R21 are compensators, and a compensator C that mainly has an image point correction action associated with zooming has negative power and moves from the wide-angle end reference position to the object side during zooming from wide to tele. It moves to the image side from the focal length, and exists on the image side of the wide-angle end reference position at the telephoto end.
SP (R22) is a diaphragm.

R23 to R39 are a relay group R having an image forming action, and R40 to R42 are glass blocks equivalent to color separation prisms.

Although the zoom ratio is as small as 14 times as compared with Numerical Embodiment 1, the angle of view 2ω = 62.9 ° at the wide-angle end is achieved.

In order to achieve this wide angle, it is necessary to satisfactorily correct various aberrations such as distortion and lateral chromatic aberration that are greatly affected by the angle of view. Also, the front lens F number is FN1 =
It is extremely bright with 1.110.

Therefore, in this embodiment, the fixed focus group is composed of one negative lens and two positive lenses. Moreover, by making the difference ΔνX between the Abbe numbers of the two negative lens materials and the positive lens material very large at 67.5, good chromatic aberration correction is achieved despite the wide angle. Also in the focus movement group, by making the refractive index of the material of the positive lens on the image side of the two positive lenses extremely high, it contributes to correction of chromatic aberration while satisfactorily correcting spherical aberration and distortion. The optical arrangement is as follows.

Numerical Embodiment 3 of FIG. 3 has substantially the same lens configuration as Numerical Embodiment 2 but achieves wider angle and higher zoom ratio by appropriate selection of power arrangement. Is 15 times.

At the same time, in order to achieve compactness, the power distribution of each lens group is strengthened and the movement amount of the variator V and the compensator C during zooming is reduced.

Therefore, the front lens F number and the front lens power share are FN1 = 1.054 and f1 / fT = 0.50, respectively.
It is a severe condition of 2. In addition, the retro ratio of the fixed focus group must be increased in order to widen the angle. Therefore, the power allocations of the fixed focus group and the focused movement group are | f11 / f1 | = 3.391, f12 / f, respectively.
1 = 0.875.

Therefore, in this embodiment, the focus fixed group is composed of one negative lens and one positive lens, and the focus moving group is composed of three positive lenses. The fixed focus group is composed of a negative lens having a relatively high refractive index and a very small Abbe number and a positive lens having a very large Abbe number, and ΔνX reaches 70. Therefore, not only spherical aberration and axial chromatic aberration but also distortion aberration due to widening of the angle, lateral chromatic aberration, etc. are well corrected. Further, since the focus moving group is composed of three positive lenses, fluctuations of various aberrations due to focus are particularly well suppressed. This is because by increasing the degree of freedom in the design of the focus movement group, (d) not only spherical aberration but also correction for fluctuations in other astigmatism, etc. can be afforded, so that the resolving power of optical performance is particularly improved. (E) Since the range of selection of lens element materials is widened, a positive lens with a very large Abbe number is adopted to improve the achromatism of the focus moving group to reduce the variation of chromatic aberration and reduce the color of the image. Effects such as reducing bleeding are derived.

In Numerical Embodiment 4 shown in FIG. 4, the angle of view at the wide-angle end is about 2ω = 42.9 °, but the zoom ratio is 44 times and the angle of view at the telephoto end is 2ω = 1.0 °. It is a high magnification zoom lens.

Since the focal length at the telephoto end is very long in this embodiment, the power sharing of the front lens group is f1 / fT = 0.3.
04 is a very severe condition. In addition to this, when the telephoto end focal length becomes long, it becomes difficult to correct spherical aberration and axial chromatic aberration.

Therefore, in the present embodiment, although the wide-angle zoom as in the numerical embodiment 3 is not used, first, the focus moving group is composed of three positive lenses, and the same effect as the numerical embodiment 3 is derived. ing. Next, in the compensator C, the R26 surface is provided with an aspherical surface, and particularly spherical aberration on the telephoto side is corrected. The achromatism is improved by arranging the positive lens element made of a material having a very large Abbe number not only in the fixed focus group but also in the fixed focus group. Aberration correction is performed by these methods so that high optical performance can be obtained even at the telephoto end of ultra-long focus.

At this time, the spherical aberration share of the focus fixed group and the focus moving group is −0.656 ≦ S1 / S2 ≦ −0.585.

Further, the achromatization is EF = −5.148 × 10 ⁻⁵ EM = 6.169 × 10 ^−5, which are small, and EF / EM = −0.834.

[0087]

As described above, according to the present invention, in the so-called four-group zoom lens, the refractive power and F number value of the front lens group are appropriately set, and the front lens group is focused and fixed. By dividing the lens into movable groups and satisfying the prescribed conditions of lens element arrangement, refractive power sharing, aberration sharing, and achromatic sharing, fluctuations in spherical aberration and chromatic aberration due to zooming and focusing can be reduced. F-number at the wide-angle end, which has high optical performance over the entire zoom range and the entire focus range, by reducing the astigmatism and the variation of off-axis aberrations such as curvature of field due to zooming in a well-balanced manner. A zoom lens having a high zoom ratio can be achieved with a large aperture ratio of about 6 and a zoom ratio of about 14 to 44.

[Brief description of drawings]

FIG. 1 is a lens cross-sectional view at a wide-angle end according to Numerical Example 1 of the present invention.

FIG. 2 is a lens cross-sectional view at a wide-angle end according to Numerical Example 2 of the present invention.

FIG. 3 is a lens cross-sectional view at a wide-angle end according to Numerical Example 3 of the present invention.

FIG. 4 is a lens cross-sectional view at a wide-angle end according to Numerical Example 4 of the present invention.

FIG. 5 shows a focal length f = 11.1.
28 aberration diagrams

FIG. 6 shows a focal length f = 43.
77 aberration diagram

FIG. 7: Focal length f = 16 of Numerical Embodiment 1 of the present invention
Aberration diagram of 9.22

FIG. 8 is a focal length f of the numerical example 2 of the present invention f = 9.0.
Aberration diagram

FIG. 9 shows a focal length f = 18.
0 aberration diagram

FIG. 10: Focal length f = 3 of Numerical Example 2 of the present invention
Aberration diagram of 6.0

FIG. 11 is a focal length f = 7 of Numerical Embodiment 2 of the present invention.
Aberration diagram of 2.0

FIG. 12 is a focal length f = 12 of Numerical Embodiment 2 of the present invention.
Aberration diagram of 6.0

FIG. 13 shows a focal length f = 8.
Aberration diagram of 5

FIG. 14 is a focal length f = 1 of the numerical value example 3 according to the present invention.
Aberration diagram of 7.0

FIG. 15 is a focal length f = 3 of Numerical Embodiment 3 of the present invention.
Aberration diagram of 4.0

FIG. 16 is a focal length f = 6 of Numerical Embodiment 3 of the present invention.
Aberration diagram of 8.0

FIG. 17: Focal length f = 12 of Numerical Example 3 of the present invention
Aberration diagram of 7.5

FIG. 18 is a focal length f = 1 of the numerical value example 4 of the present invention.
Aberration diagram of 4.0

FIG. 19 is a focal length f = 2 of Numerical Embodiment 4 of the present invention.
Aberration diagram of 7.29

FIG. 20 shows a focal length f = 9 according to Numerical Embodiment 4 of the present invention.
Aberration diagram of 7.69

FIG. 21 is a focal length f = 35 of Numerical Embodiment 4 of the present invention.
Aberration diagram of 9.24

FIG. 22 shows a focal length f = 61 of Numerical Embodiment 4 of the present invention.
Aberration diagram of 6.0

[Explanation of symbols]

 F First group (focus group) F11 Focus fixed group F12 Focus moving group V Second group (variator) C Third group (compensator) R Fourth group (relay group) G Glass block SP Aperture ee line g g line ΔS Sagittal image plane ΔM Meridional image plane

Claims (3)

[Claims] 1. A first lens unit having a positive refracting power in order from the object side, a second lens unit having a negative refracting power for zooming, a third lens unit for correcting an image plane variation due to zooming, and a fixed lens during zooming. Having the image forming action of
In the zoom lens having a group, the first group is composed of an eleventh group that is fixed during focusing and a twelfth group that moves toward the object side when focusing on an object at infinity from a close-up object. Has two independent lenses, at least one negative lens LN11 and at least one positive lens LN12,
The second group has at least two positive lenses, and the focal length and F number of the entire system at the telephoto end are fT and FN, respectively.
T, the focal length of the first lens group and the F number are f1 and FN, respectively.
1. The focal lengths of the 11th and 12th lens units are f11 and f, respectively.
12. When the difference in Abbe number between the materials of the negative lens LN11 and the positive lens LP12 is ΔνX 1.04 <FN1 <1.55 where FN1 = f1 /
(FT / FNT) A zoom lens characterized by satisfying a condition of 0.28 <f1 / fT <0.80 55 <ΔνX 3 <| f11 / f1 | 0.77 <f12 / f1 <1.10. 2. The sum of the third-order aberration coefficients of the spherical aberrations of the lens surfaces of the 11th and 12th lens groups at the telephoto end is S, respectively.
The zoom lens according to claim 1, wherein, when S1 and S2 are satisfied, a condition of S1 <0 <0 <S2−0.90 <S1 / S2 <−0.56 is satisfied in the entire focus range. 3. The focal length and the Abbe number of the material of the i-th lens of the 11th group are f11i and ν11i, respectively, and the focal length and the Abbe number of the material of the i-th lens of the 12th group are f12i, respectively. , Ν12i [Equation 1] The zoom lens according to claim 1, wherein the following condition is satisfied.