JPH06102456A - Zoom lens with variable power range and super telephoto mode - Google Patents

Abstract

PURPOSE:To obtain the zoom lens with the variable power range and the super telephoto mode which can be widened in power variation range and provide super telephotography by utilizing lens groups as part of a rear focus type zoom lens. CONSTITUTION:Four lens groups which are a 1st group L1 with positive refracting power, a 2nd group L2 with negative refracting power, a 3rd group L3 with positive refracting power, and a 4th group L4 with positive refracting power are arranged in order from an object side. This zoom lens has 1st power variation wherein the power is varied by moving the 2nd group L2 along the optical axis and the 4th group L4 is moved to compensate image plane variation accompanying the power variation and also put the lens in focus and 2nd power variation wherein the power is varied by moving the 2nd group L2 along the optical axis after moving the 3rd group L3 by a specific quantity along the optical axis and the 4th group L4 is moved to compensate image plane variation accompanying the power variation and also put the lens in focus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens having a variable zoom range and a zoom lens having a super-telephoto range. In particular, in a rear focus type zoom lens, a predetermined lens group is appropriately moved on the optical axis. 1-magnification and 2nd
The variable magnification range (focal length range) can be selectively switched using two variable magnification operations for variable magnification for shooting, or the focal length at the telephoto end can be displaced to a longer position for super telephoto. The present invention relates to a zoom lens having a variable zoom range and a zoom lens having super telephoto, which are suitable for still cameras, video cameras, and the like.

[0002]

2. Description of the Related Art Conventionally, various methods for displacing a zoom lens in a zoom range have been proposed. For example, a so-called rear converter method or zoom for displacing the focal length range of the entire system by inserting a rear converter lens group or extender lens group having a positive or negative refractive power between the final lens surface of the zoom lens and the image surface. There has been proposed an afocal converter method in which an afocal converter lens group having an infinite focal length is attached in front of the lens to expand or reduce the focal length range of the entire system.

In addition to this, there is a method of simply changing the zoom ratio of the zoom lens to expand the zoom range. For example, there is a method of increasing the amount of movement of the lens group for zooming, increasing the refracting power of the lens group for zooming, or increasing the number of lens groups for zooming.

[0004]

Among the methods of displacing the zooming range of the zoom lens, the rear converter method can relatively reduce the tele ratio, but the rear converter lens group alone can improve various aberrations. Since it is necessary to make corrections, the lens structure inevitably becomes complicated and large.

On the other hand, the afocal converter method can relatively easily widen the angle of the zoom lens system and increase the distance to the telephoto side, but since the lens group is mounted in front of the lens, the lens group becomes large. Tend to come.

Further, both of the converter methods are not suitable for quick photographing and portability because a lens group for the converter must be always provided in addition to the main body of the zoom lens.

Further, in the method of changing the zoom ratio of the zoom lens, the total lens length becomes long, the amount of aberration generated over the entire zoom range becomes large, and it becomes difficult to satisfactorily correct the aberration fluctuation during zooming. There are problems such as doing.

A first object of the present invention is to provide a rear focus type zoom lens in which a lens unit other than the first unit on the object side is moved on the optical axis for focusing, and a predetermined lens unit is moved on the optical axis. The first variable and the second variable that perform the scaling, 2
By appropriately selecting one of the two zooming operations, a zoom lens with a variable zooming range that can switch the zooming range quickly and shoot while maintaining the overall lens length constant and maintaining good optical performance In offer.

A second object of the present invention is to further increase the focal length at the telephoto end by moving a predetermined lens group on the optical axis at the zoom position at the telephoto end using the rear focus type zoom lens described above. An object of the present invention is to provide a zoom lens having a super-telephoto that enables shooting at a super-telephoto with a focal length.

[0010]

The zoom lens having a variable magnification range according to the present invention comprises (1-a) a first group having a positive refractive power, a second group having a negative refractive power, and a positive refractive power in order from the object side. It has four lens groups, a third lens group having a power and a fourth lens group having a positive refractive power, and the second lens group is moved along the optical axis to perform zooming, and the image plane variation due to zooming is The fourth lens group is moved and corrected, and the fourth lens group is moved to perform focusing. First zooming and the third lens group are moved in the optical axis direction by a predetermined amount, and then the second lens group is moved in the optical axis direction. And the second zooming for performing focusing by moving the fourth lens group while correcting the image plane variation due to the zooming by moving the fourth lens group. I am trying.

(1-b) The first group having a positive refractive power, the second group having a negative refractive power, the third group having a positive refractive power, and the fourth group having a positive refractive power are arranged in this order from the object side. Has two lens groups, the second
The lens unit is moved to the image plane side to change the magnification from the wide-angle end to the telephoto end, and the image plane variation due to the magnification change is corrected by moving the fourth unit and moving the fourth unit. The first zooming is performed and the third lens group is moved in the object side direction by a predetermined amount, and then the second lens group is moved in the image plane side direction to perform zooming. The group is moved to correct and the fourth
A second variable power for performing focusing by moving the lens group, wherein the focal length at the wide-angle end of the second variable power is longer than the focal length at the wide-angle end of the first variable power.

The zoom lens having super-telephoto according to the present invention comprises (1-c) a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and It has four lens groups of the fourth group having a positive refractive power, and the second group is moved to the image plane side to perform the magnification change from the wide-angle end to the telephoto end, and the image plane variation due to the magnification change is The fourth lens group is moved and corrected, and the fourth lens group is moved to perform focusing, and the third lens group is moved to the object side by a predetermined amount at the first zooming position and the zoom position at the telephoto end of the first zooming group. The focus variation that occurs at this time is corrected by moving the fourth lens group, and the focal length of the entire system is displaced to the longer side to provide super telephoto.

[0013]

EXAMPLE 1 FIG. 1 is a schematic view of a principal part showing a paraxial refractive power arrangement of Example 1 of a zoom lens having a variable magnification range according to the present invention.

FIG. 1A shows the position on the optical axis of each lens unit in the first magnification change, where (A-W) is the wide-angle end,
(AT) indicates the telephoto end. FIG. 1B shows the position on the optical axis of each lens group at the second magnification,
(B-W) indicates the wide-angle end, and (BT) indicates the telephoto end. The second zooming of FIG. 1B is a zooming in a focal length range (variable range) including a longer focal length than the focal length range (variable range) of the first zooming of FIG. 1A. It's working.

In the figure, L1 is a first group having a positive refractive power, L2 is a second group having a negative refractive power, L3 is a third group having a positive refractive power, and L4.
Is the fourth group of positive refractive power. SP is an aperture stop,
It is arranged in front of the third unit L3. FL is an image plane (film surface).

In the first magnification change of FIG. 1A, the second lens unit L2 is moved to the image plane side as indicated by an arrow ZV at the time of magnification change from the wide-angle end to the telephoto end, and the image plane variation due to the magnification change is caused. 4th group L
4 is moved and corrected.

Further, a rear focus type in which focusing is performed by moving the fourth lens unit on the optical axis is adopted. The solid curve 4a and the dotted curve 4b of the fourth group shown in the same figure represent image plane fluctuations due to zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and a near object, respectively. The movement locus for correction is shown. The first and third groups are fixed during zooming and focusing.

In the present embodiment, the fourth lens unit is moved to correct the image plane variation due to zooming, and the fourth lens unit is moved to perform focusing. Curve 4 in the figure
As indicated by a and 4b, the zoom lens is moved so as to have a convex locus toward the object side during zooming from the wide-angle end to the telephoto end.
As a result, the space between the third group and the fourth group is effectively used, and the total lens length is effectively shortened.

In this embodiment, for example, when focusing from an object at infinity to a near object at the telephoto end, the fourth lens unit is moved forward as indicated by a straight line 4c in the figure.

Switching from the first variable magnification shown in FIG. 1A to the second variable magnification shown in FIG. 1B is performed as follows.

First, in FIG. 1A, the third lens unit L3 is moved toward the object side on the optical axis by a predetermined amount as shown by an arrow 3a and stopped. Then, the focus variation at this time is corrected by moving the fourth lens unit L4 on the optical axis as indicated by the arrow 4d. After that, zooming and focusing are performed in the same manner as the first zooming in FIG.

That is, the second lens unit L2 is moved to the image plane side as indicated by the arrow ZV to change the magnification from the wide-angle end to the telephoto end, and the image plane change caused by the magnification change is caused on the optical axis of the fourth lens unit L4. It is moved and corrected.

Further, the fourth lens unit L4 is moved along the optical axis in the same manner as the first variable power magnification shown in FIG. 1A to perform focusing.

In Numerical Embodiment 1 which will be described later, the focal length f = 1 to 6 for the first variable power and the focal length f = 1.49 for the second variable power.
At 8.92, switching is performed within this focal length range.

In this embodiment, the wide-angle end (AW) at the first magnification is changed.
Each element is set so that the focal length at the wide-angle end (BW) at the second magnification becomes longer than the focal length at.

In the present embodiment, the rear focus system as described above is employed to increase the effective lens diameter of the first lens group as compared with the case where the first lens group is extended and focused in such a zoom type. To prevent it.

By arranging the aperture stop immediately before the third lens unit, aberration fluctuations due to the movable lens unit are reduced, and by shortening the distance between the lens units in front of the aperture stop, the diameter of the front lens is reduced. Achieved easily.

By switching between the first variable magnification and the second variable magnification in the above-described lens structure, the focal length range can be displaced quickly and easily, and photography can be performed with the focal length range expanded.

In particular, in the present embodiment, the combined lateral magnification of the third and fourth groups when focusing on an object at infinity at the wide-angle end in the first magnification change is βS, and in the second magnification change When the combined lateral magnification of the third group and the fourth group when focusing on an object at infinity at the wide-angle end is βL, 1.1 <βL / βS <2.0 ... (1) βL × βS ≦ 1 (2) The condition is satisfied.

As a result, while keeping the total lens length constant,
The displacement in the focal length range is effectively performed.

In the zoom lens of this embodiment, the virtual image formed by the first group and the second group is converted into a real image by the third group and the fourth group, and the photosensitive surface FL is formed.
Is imaged.

In (A-W) of FIG. 1A, the third group and the fourth group
The composite lateral magnification βS of the group is set to be a reduction magnification rather than a unity magnification.
In (B-W) of (B), the combined lateral magnification β of the third group and the fourth group is β.
L is an enlargement ratio rather than a unity magnification.

Then, the lateral magnification ratio (βL / β
S) is set appropriately while keeping the total lens length constant,
Focal length range (variable range) while maintaining good optical performance
The displacement of

When the lower limit of conditional expression (1) is exceeded, the effect of switching the focal length range is reduced. On the other hand, if the upper limit of conditional expression (1) is exceeded, the effect of switching the focal length range will increase, but the amount of movement of the third and fourth groups will increase and the overall lens system will increase in size.

In the present embodiment, the fourth lens unit is moved on the optical axis at the time of focusing and image plane variation due to zooming. Conditional expression (2) is for appropriately setting the distance between the third group and the fourth group for the movement of the fourth group at this time so that the total lens length does not become too long.

If the conditional expression (2) is not satisfied, the distance between the third group and the fourth group in the second zooming becomes smaller than that in the first zooming, and the fourth group is zoomed and focused. It is not good because it becomes difficult to move on the optical axis.

FIG. 16 is a schematic view of a principal part showing a paraxial refractive power arrangement of Example 1 of the zoom lens having super telephoto of the present invention.

FIG. 16A shows the wide-angle end at the first magnification, and FIG.
FIG. 16B shows the position on the optical axis of each lens group at the telephoto end at the first magnification and FIG. FIG. 16 (C)
The focal length at the super-telephoto is longer than the focal length at the telephoto end in FIG.

In the figure, L1 is the first group having a positive refractive power, L2 is the second group having a negative refractive power, L3 is the third group having a positive refractive power, and L4.
Is the fourth group of positive refractive power. SP is an aperture stop,
It is arranged in front of the third unit L3. FL is an image plane (film surface).

At the time of zooming from the wide-angle end in FIG. 16A to the telephoto end in FIG. 16B, the second lens unit L2 is indicated by an arrow ZV.
Is moved to the image surface side, and the image surface variation due to zooming is corrected by moving the fourth lens unit L4.

Further, a rear focus type is adopted in which the fourth lens unit is moved on the optical axis for focusing. The solid curve 4a and the dotted curve 4b of the fourth group shown in the same figure represent image plane fluctuations due to zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and a near object, respectively. The movement locus for correction is shown. The first and third groups are fixed during zooming and focusing.

In this embodiment, the fourth lens group is moved to correct the image plane variation due to zooming, and the fourth lens group is moved to perform focusing. Curve 4 in the figure
As indicated by a and 4b, the zoom lens is moved so as to have a convex locus toward the object side during zooming from the wide-angle end to the telephoto end.
As a result, the space between the third group and the fourth group is effectively used, and the total lens length is effectively shortened.

In this embodiment, for example, when focusing from an object at infinity to a near object at the telephoto end in FIG. 16B, the fourth lens unit is moved forward as indicated by a straight line 4c in the figure. ing.

From the telephoto end of the first variable magnification shown in FIG.
Switching to 6 (C) to super-telephoto is performed as follows.

First, in FIG. 16B, the third lens unit L3 is moved toward the object side on the optical axis by a predetermined amount as shown by an arrow 3a and stopped. Then, the focus variation at this time is corrected by moving the fourth lens unit L4 on the optical axis as indicated by the arrow 4d.

In Numerical Example 3 described later, the focal length fT at the telephoto end (FIG. 16B) at the first magnification is fT = 7.62,
The focal length fTT of super-telephoto (FIG. 16C) is fTT = 1.
It is 1.42.

In this embodiment, each element is set in this way,
By switching each element quickly and easily, a focal length (fT) longer than the focal length (fT) at the telephoto end can be obtained.
T) is shooting at super telephoto.

In the present embodiment, in such a zoom type, the rear focus system as described above is adopted as compared with the case where the first lens unit is extended to perform focusing, thereby increasing the effective lens diameter of the first lens unit. To prevent it.

By arranging the aperture stop immediately before the third lens unit, the variation in aberration due to the movable lens unit is reduced, and by shortening the distance between the lens units in front of the aperture stop, the diameter of the front lens is reduced. Achieved easily.

In particular, in the present embodiment, the combined lateral magnification of the third group and the fourth group when focusing on an object at infinity at the telephoto end in the first variable magnification is βSS, and the combined lateral magnification in the super-telephoto is When the combined lateral magnification of the third group and the fourth group is βLL, −0.95 <βSS <−0.7 (3) −1.40 <βLL <−1.05・ ・ ・ ・ ・ ・ ・ ・ (4) is characterized by satisfying the following condition.

In the zoom lens of this embodiment, the virtual image formed by the first and second groups is converted into a real image by the third and fourth groups, and the photosensitive surface FL is obtained.
Is imaged.

At the telephoto end in FIG. 16B, the combined lateral magnification βSS of the third group and the fourth group is set to be a reduction magnification rather than the equal magnification, and FIG.
At super telephoto in (C), combined lateral magnification βLL of the third and fourth groups
Is a magnification factor rather than a unity magnification.

Then, the lateral magnification ratio (βLL / β
(SS) is set appropriately while maintaining good optical performance,
Shooting at super telephoto.

When the lower limit value of the conditional expression (3) or the upper limit value of the conditional expression (4) is exceeded, the effect of switching to super-telephoto (the effect of changing the focal length) becomes small. On the other hand, if the upper limit of conditional expression (3) or the lower limit of conditional expression (4) is exceeded, the effect of switching to super-telephoto will be large, but the amount of movement of the third and fourth groups will be large, and the entire lens system will become large. Is not good as it becomes larger.

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 the i-th lens order from the object side, respectively. The refractive index of glass and the Abbe number. The last two lens surfaces are glass blocks such as face plates.

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 to light, and R as a paraxial radius of curvature,
When K, B, C, D, and E are aspherical coefficients, respectively

[0057]

[Equation 1] It is expressed by

Zoom Lens with Variable Zoom Range Numerical Example 1 f = 1 to 6 fno = 1: 1.75 to 2.32 ω = 58.89 ° to 9.64 ° R 1 = 6.752 D 1 = 0.168 n 1 = 1.80518 ν 1 = 25.4 R 2 = 2.603 D 2 = 0.965 n 2 = 1.60311 ν 2 = 60.7 R 3 = -14.422 D 3 = 0.033 R 4 = 2.317 D 4 = 0.494 n 3 = 1.69350 ν 3 = 53.2 R 5 = 9.389 D 5 = Variable R 6 = 8.372 D 6 = 0.084 n 4 = 1.77250 ν 4 = 49.6 R 7 = 0.865 D 7 = 0.455 R 8 = -1.112 D 8 = 0.084 n 5 = 1.69680 ν 5 = 55.5 R 9 = 1.174 D 9 = 0.286 n 6 = 1.84666 ν 6 = 23.8 R10 = -24.482 D 10 = Variable R11 = (Aperture) D 11 = Variable * R12 = 2.682 D 12 = 0.505 n 7 = 1.58313 ν 7 = 59.4 R13 = -5.138 D 13 = Variable R14 = 2.875 D 14 = 0.160 n 8 = 1.84666 ν 8 = 23.8 R15 = 1.245 D 15 = 0.788 n 9 = 1.58313 ν 9 = 59.4 R16 = -3.531 D 16 = 0.792 R17 = ∞ D 17 = 0.893 n10 = 1.51633 ν10 = 64.2 R18 = ∞ 12th and 16th surfaces are aspherical surfaces 12th surface 16th surface R = 2.682 R = −3.531 K = 5.435 × 10 ⁻¹ K = 3.968 × 10 ⁻¹ B = −2 .753 × 10 ^-2 B ^{-2.950 × 10 -3 C = 6.370 ×} 10 -3 C = 3.418 × 10 -2 D = -5.687 × 10 -3 D = -6.239 × 10 -2 E = 1. 122 × 10 ⁻³ E = 2.937 × 10 ⁻² βL / βS = 1.487, βL × βS = 0.842 First scaling

[0059]

[Table 1] Second magnification

[0060]

[Table 2] Zoom lens with variable zoom range Numerical example 2 f = 1 to 6 fno = 1: 1.82 to 2.5 2 ω = 53.15 ° to 9.53 ° R 1 = 6.762 D 1 = 0.166 n 1 = 1.80518 ν 1 = 25.4 R 2 = 2.930 D 2 = 0.863 n 2 = 1.60311 ν 2 = 60.7 R 3 = -13.017 D 3 = 0.033 R 4 = 2.220 D 4 = 0.456 n 3 = 1.69350 ν 3 = 53.2 R 5 = 7.022 D 5 = Variable R 6 = 6.653 D 6 = 0.083 n 4 = 1.77250 ν 4 = 49.6 R 7 = 1.012 D 7 = 0.332 R 8 = -1.673 D 8 = 0.083 n 5 = 1.69680 ν 5 = 55.5 R 9 = 1.151 D 9 = 0.175 R10 = 1.487 D 10 = 0.283 n 6 = 1.84666 ν 6 = 23.8 R11 = 3.532 D 11 = Variable R12 = (Aperture) D 12 = Variable * R13 = 2.731 D 13 = 0.500 n 7 = 1.58313 ν 7 = 59.4 R14 = -4.251 D 14 = Variable R15 = 3.681 D 15 = 0.158 n 8 = 1.84666 ν 8 = 23.8 R16 = 1.514 D 16 = 0.609 n 9 = 1.58313 ν 9 = 59.4 * R17 = -3.470 D 17 = 0.783 R18 = ∞ D 18 = 0.883 n10 = 1.51633 ν10 = 64.2 R19 = ∞ The thirteenth surface and the seventeenth surface are aspherical surfaces The thirteenth surface Seventeenth surface R = 2.731 R = -3.470 K = 5.613 × 10 ⁻¹ K = 3.925 × 10 ⁻¹ B = -2.895 × 10 ^-2 B = 1.738 × 10 ⁻³ C = 7.081 × 10 ⁻³ C = 4.245 × 10 ⁻² D = −6.143 × 10 ⁻³ D = −6.738 × 10 ⁻² E = 1.236 × 10 ⁻³ E = 3.242 × 10 ⁻² βL / βS = 1.497, βL × βS = 0.867 First scaling

[0061]

[Table 3] Second magnification

[0062]

[Table 4] Numerical example 1 of f = 1 to 7.62 (11.42) fno = 1: 1.85 to 2.8 (4.2) 2ω = 55.4 ° to 7.8 ° (5.2 °) R 1 = 4.858 D 1 = 0.163 n 1 = 1.80518 ν 1 = 25.4 R 2 = 2.466 D 2 = 0.696 n 2 = 1.60311 ν 2 = 60.7 R 3 = -51.893 D 3 = 0.032 R 4 = 2.484 D 4 = 0.409 n 3 = 1.69350 ν 3 = 53.2 R 5 = 9.358 D 5 = Variable R 6 = 3.183 D 6 = 0.082 n 4 = 1.77250 ν 4 = 49.6 R 7 = 0.839 D 7 = 0.277 R 8 = -1.329 D 8 = 0.082 n 5 = 1.69680 ν 5 = 55.5 R 9 = 1.238 D 9 = 0.172 R10 = 1.570 D 10 = 0.278 n 6 = 1.84666 ν 6 = 23.8 R11 = 4.659 D 11 = Variable R12 = (Aperture) D 12 = Variable * R13 = 2.455 D 13 = 0.491 n 7 = 1.58313 ν 7 = 59.4 R14 = -10.249 D 14 = Variable R15 = 2.432 D 15 = 0.155 n 8 = 1.84666 ν 8 = 23.8 R16 = 1.233 D 16 = 0.639 n 9 = 1.58313 ν 9 = 59.4 * R17 = -6.059 D 17 = 0.770 R18 = ∞ D 18 = 0.868 n10 = 1.51633 ν10 = 64.2 R19 = ∞ The 13th and 17th surfaces are aspherical aspherical coefficients 13th surface 17th surface R = 2.455 R = 6.059 K = 6.873 × 10 ^{− 1} K = 9.244 x 10 ^-1 B = -2.742 x 10 ^-2 B = -6.670 x 10 ^-3 C = 8.092 x 10 ^-3 C = 5.002 x 10 ^-2 D = -6.197 x 10 ^-3 D = −7.593 × 10 ⁻² E = 1.441 × 10 ⁻³ E = 3.779 × 10 ⁻²

[0063]

[Table 5] Zoom lens with super-telephoto Numerical Example 2 f = 1 to 7.62 (11.50) fno = 1: 1.83 to 2.66 (4.0) 2 ω = 55.4 ° to 5.2 ° R 1 = 8.734 D 1 = 0.164 n 1 = 1.80518 ν 1 = 25.4 R 2 = 2.916 D 2 = 0.914 n 2 = 1.60311 ν 2 = 60.7 R 3 = -7.889 D 3 = 0.032 R 4 = 2.271 D 4 = 0.434 n 3 = 1.69350 ν 3 = 53.2 R 5 = 6.070 D 5 = Variable R 6 = 4.344 D 6 = 0.082 n 4 = 1.77250 ν 4 = 49.6 R 7 = 0.910 D 7 = 0.407 R 8 = -0.969 D 8 = 0.082 n 5 = 1.69680 ν 5 = 55.5 R 9 = 1.010 D 9 = 0.278 n 6 = 1.84666 ν 6 = 23.8 R10 = 18.066 D 10 = Variable R11 = (Aperture) D 11 = Variable * R12 = 2.399 D 12 = 0.492 n 7 = 1.58313 ν 7 = 59.4 R13 = -6.944 D 13 = 1.166 R14 = 2.921 D 14 = 0.155 n 8 = 1.84666 ν 8 = 23.8 R15 = 1.293 D 15 = 0.658 n 9 = 1.58313 ν 9 = 59.4 * R16 = -4.430 D 16 = 0.770 R17 = ∞ D 17 = 0.869 n10 = 1.51633 ν10 = 64.2 R18 = ∞ 12th surface and 16th surface are aspherical surfaces Aspherical coefficient 12th surface 16th surface R = 2.399 R = -4.430 K = 5.742 × 10 ⁻¹ K = 6.204 × 10 ^{− 1} B = −2.841 × 10 ⁻² B = −5.182 × 10 ⁻⁴ C = 6.722 × 10 ⁻³ C = 4.436 × 10 ⁻² D = −6.912 × 10 ⁻³ D = −7.574 × 10 ^{− 2} E = 1.449 × 10 ⁻³ E = 3.769 × 10 ⁻²

[0064]

[Table 6]

[0065]

According to the present invention, in a rear focus type zoom lens in which a lens unit other than the first lens unit on the object side is moved on the optical axis for focusing, a predetermined lens unit is moved on the optical axis to change the lens. By appropriately selecting the two zooming operations of the first zooming and the second zooming that perform zooming, the zooming range can be swiftly maintained while maintaining the overall lens length constant and maintaining good optical performance. It is possible to achieve a zoom lens with a variable magnification range that can be switched and photographed.

Further, by using the rear focus type zoom lens described above and moving a predetermined lens group on the optical axis at the zoom position at the telephoto end, photographing at a super telephoto with a focal length further longer than the focal length at the telephoto end. It is possible to achieve a zoom lens having a super telephoto that enables

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a paraxial refractive power arrangement of a zoom lens having a variable magnification range according to the present invention.

FIG. 2 is a lens cross-sectional view of a numerical example 1 of a zoom lens having a variable zoom range according to the present invention.

FIG. 3 is a lens sectional view of a numerical example 2 of a zoom lens having a variable magnification range according to the present invention.

FIG. 4 is an aberration diagram at the wide-angle end at the first magnification in Numerical Example 1 of the zoom lens having a variable magnification range according to the present invention.

FIG. 5 is an aberration diagram in the middle of the first magnification in Numerical Example 1 of the zoom lens having a variable magnification range according to the present invention.

FIG. 6 is an aberration diagram at the telephoto end of the first variable magnification example of the numerical example 1 of the zoom lens having a variable magnification range according to the present invention.

FIG. 7 is an aberration diagram at the wide-angle end at the second magnification in the numerical example 1 of the zoom lens having a variable magnification range according to the present invention.

FIG. 8 is an aberration diagram in the middle of the second magnification of the numerical example 1 of the zoom lens having a variable magnification range according to the present invention.

FIG. 9 is an aberration diagram at the telephoto end of the second variable power example of the numerical example 1 of the variable magnification range variable zoom lens of the present invention.

FIG. 10 is an aberration diagram at the wide-angle end at the first magnification in Numerical Example 2 of the zoom lens having a variable magnification range according to the present invention.

FIG. 11 is an aberration diagram in the middle of the first magnification in Numerical Example 2 of the zoom lens having a variable magnification range according to the present invention.

FIG. 12 is an aberration diagram at the telephoto end for the first variable magnification of Numerical Example 2 of the variable magnification range variable zoom lens of the present invention.

FIG. 13 is an aberration diagram at the wide-angle end at the second magnification of Numerical Example 2 of the zoom lens having a variable magnification range according to the present invention.

FIG. 14 is an aberration diagram in the middle of the second magnification of the numerical example 2 of the zoom lens having a variable magnification range according to the present invention.

FIG. 15 is an aberration diagram at the telephoto end for the second variable power according to the numerical example 2 of the zoom lens having a variable zoom range according to the present invention.

FIG. 16 is a schematic view of a main part of a paraxial refractive power arrangement of a zoom lens having super telephoto according to the present invention.

FIG. 17 is a lens cross-sectional view of a numerical example 1 of a zoom lens having super telephoto according to the present invention.

FIG. 18 is a lens sectional view of a numerical example 2 of a zoom lens having super telephoto according to the present invention.

FIG. 19 is an aberration diagram at a wide-angle end of a numerical example 1 of the zoom lens having super telephoto according to the present invention.

FIG. 20 is an intermediate aberration diagram of Numerical example 1 of the zoom lens having super telephoto according to the present invention.

FIG. 21 is an aberration diagram at a telephoto end of a numerical example 1 of the zoom lens having super-telephoto according to the present invention.

FIG. 22 is an aberration diagram of super telephoto of a numerical example 1 of the zoom lens having super telephoto of the present invention.

FIG. 23 is an aberration diagram at a wide-angle end of a numerical example 2 of the zoom lens having super telephoto according to the present invention.

FIG. 24 is an intermediate aberration diagram of Numerical example 2 of the zoom lens having super telephoto according to the present invention.

FIG. 25 is an aberration diagram at a telephoto end of a numerical example 2 of a zoom lens having super-telephoto according to the present invention.

FIG. 26 is an aberration diagram of super telephoto of a numerical example 2 of the zoom lens having super telephoto of the present invention.

[Explanation of symbols]

 L1 1st group L2 2nd group L3 3rd group L4 4th group SP Aperture d d line g g line ΔS Sagittal image surface ΔM Meridional image surface

Claims (5)

[Claims] 1. Four lens groups, in order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a fourth group having a positive refractive power. And moving the second lens unit on the optical axis to perform zooming, and to change the image plane due to zooming to the fourth
The first lens group is moved for correction while the fourth lens group is moved to perform focusing, and the third lens group is moved in the optical axis direction by a predetermined amount, and then the second lens group is moved in the optical axis direction. Second zooming is performed by moving the fourth lens group to correct the image plane variation due to the zooming by moving the fourth lens group.
A zoom lens having a variable zoom range characterized by having a variable power. 2. Four lens groups, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a fourth group having a positive refractive power, in order from the object side. And moving the second lens group toward the image plane side to perform zooming from the wide-angle end to the telephoto end, and moving the fourth lens group to correct the image plane variation due to zooming and First zooming for moving the group for focusing and moving the third group for a predetermined amount in the object side direction, and then for moving the second group in the image plane side for zooming. A second variable power for moving the fourth lens group to correct the image plane variation and for focusing by moving the fourth lens group, and the focal length at the wide-angle end of the second variable power is the first focal length. A zoom lens with a variable zoom range that is longer than the focal length of the zoom lens at the wide-angle end. 3. The combined lateral magnification of the third group and the fourth group when focusing on an object at infinity at the wide-angle end at the first magnification change is βS, and at the wide-angle end at the second magnification change to infinity. The combined lateral magnification of the third group and the fourth group when focusing on a distant object is β
The zoom lens having a variable magnification range according to claim 2, wherein the condition of 1.1 <βL / βS <2.0 βL × βS ≦ 1 when L is satisfied. 4. A four-lens group consisting of a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a fourth group having a positive refractive power in order from the object side. And moving the second lens group toward the image plane side to perform zooming from the wide-angle end to the telephoto end, and moving the fourth lens group to correct the image plane variation due to zooming and The first lens group is moved for focusing, and the third lens group is moved to the object side by a predetermined amount at the zoom position at the telephoto end of the first lens group, and the focus variation that occurs at this time is caused by the fourth lens group.
A zoom lens with super telephoto, characterized in that the focal length of the entire system is displaced toward the longer side to make it super telephoto. 5. The composite lateral magnification of the third group and the fourth group when focusing on an object at infinity at the telephoto end in the first magnification change is βSS, and the third group in the super-telephoto is The super-telephoto lens according to claim 4, wherein the condition of -0.95 <βSS <-0.7-1.40 <βLL <-1.05 is satisfied when the combined lateral magnification of the fourth group is βLL. Zoom lens with.