JP2000056222A - Variable focal distance lens system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wide angle zoom lens miniaturized and suitable for magnification ratio increase by making a length along with an optical axis from a 2nd lens group to a 4th lens group and a focal distance in the state of wide angle end satisfy specified conditions. SOLUTION: This system has 1st and 4th lens groups G1 and G4 having positive refracting power and 2nd, 3rd and 5th lens groups G2, G3 and G5 having negative refracting power. A variable gap is formed between the respective lens groups, each variable gap is increased/decreased in the case of changing a lens position state from wide angle end state to telescopic end state, all the lens groups are moved to the side of an object, the 2nd lens group G2 and 4th lens group G4 are integrally moved, and an aperture stop is arranged between the 2nd lens group G2 and 4th lens group G4. Then, a length ΣD24 along with the optical axis from the lens face of the 2nd lens group G2 on the most object side to the lens face of the 4th lens group G4 on the most image side and a focal distance fw in the wide angle state satisfy the condition of 0.5<ΣD24/fw<0.7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable focal length lens system, and more particularly to a variable focal length lens system which is compact and has high optical performance even when the zoom ratio exceeds 3.5.

[0002]

2. Description of the Related Art In recent years, a zoom lens is generally used as a photographing lens system used in a still camera, a video camera, and the like, and a so-called high zoom ratio zoom lens having a zoom ratio exceeding 3 times is mainly used. It has become. As the zoom ratio increases, a multi-unit zoom lens composed of three or more movable lens groups is often used for these high zoom ratio zoom lenses.

For example, a positive / negative two-group type (constituting a positive lens group and a negative lens group in order from the object side and changing the focal length by changing the distance between the lens groups) is a lens group constituting a lens system. When the zoom ratio increases, the variation in off-axis aberration that occurs when the lens position changes from the wide-angle end state to the telephoto end state cannot be corrected satisfactorily, resulting in good optical performance. I can't get it.

Therefore, if a multi-unit zoom lens having three or more lens units is employed, the degree of freedom in selecting the zoom trajectory of each lens unit constituting the lens system is increased. Variations in off-axis aberrations that occur when the lens position changes can be corrected well, and the zoom ratio can be increased. In particular, in the case of an integrated camera in which the imaging optical system and the camera body are integrated, portability is emphasized, and miniaturization and weight reduction are required. Various proposals have been made.

[0005] As a high zoom ratio zoom lens suitable for miniaturization and weight reduction, specifically, a positive / negative three-group type (consisting of two positive lens groups and one negative lens group in order from the object side). ), And a positive-negative positive-negative four-group configuration type (in order from the object side, a positive lens group, a negative lens group, a positive lens group, and a negative lens group).

[0006]

However, when the zoom ratio is increased to more than 3.5 times using the conventional positive / negative three-group configuration type, the lateral position of the negative lens group arranged closest to the image side is reduced. Magnification is very large at the telephoto end, and the fluctuation of the image plane position that occurs when the negative lens group is displaced by a small amount in the optical axis direction becomes very large, so that good optical performance cannot be obtained. There was a problem.

In addition, in the case of the four-group positive / negative / positive / negative type, the movable lens group has four groups, so that a high zoom ratio can be obtained. Remarkably, it was difficult to manufacture at low cost. An object of the present invention is to solve the above problems and to provide a small-sized and wide-angle zoom lens suitable for a high zoom ratio.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned object, and includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power,
Third lens group having negative refractive power, fourth lens group having positive refractive power
A lens group, a fifth lens group having a negative refractive power, wherein a first variable distance is formed between the first lens group and the second lens group, and the second lens group and the third lens group And a second variable interval is formed between the third lens group and the fourth lens group.
A third variable interval is formed between the lens group and the fourth lens group, and a fourth variable interval is formed between the fourth lens group and the fifth lens group. The lens position changes from the wide-angle end state to the telephoto end state. At this time, the first variable interval increases, the second variable interval increases, the third variable interval decreases, and the fourth variable interval decreases, so that all the lens groups move toward the object side. Moving, the second lens group and the fourth lens group move integrally, and an aperture stop is arranged between the second lens group and the fourth lens group. An object of the present invention is to solve the problem by configuring a variable focal length lens system that satisfies Expression (1). (1) 0.5 <ΔD24 / fw <0.7 where ΔD24 is the length along the optical axis from the lens surface closest to the object in the second lens unit to the lens surface closest to the image in the fourth lens unit. .

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A variable focal length lens system according to the present invention comprises, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a negative refractive power. And a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power.
When the lens position changes from the wide-angle end state where the focal length of the entire lens system is the shortest to the telephoto end state where the focal length of the entire lens system is the longest, a lens is formed between the first lens group and the second lens group. The first variable interval increases, the second variable interval formed between the second lens group and the third lens group decreases, and the first variable interval is formed between the third lens group and the fourth lens group. All the lens groups are moved to the object side so that the third variable interval increases and the fourth variable interval formed between the fourth lens group and the fifth lens group decreases, as shown below. By achieving the function of each lens unit, a variable focal length lens system having a small size and a high zoom ratio is achieved.

The taking lens system for a lens-integrated camera in which the taking lens system is attached to the camera body as in the present invention has no restriction on the back focus. Therefore, in the present invention, the fifth lens group is given a negative refractive power, so that a telephoto type refractive power arrangement in which the negative lens group is arranged closest to the image side of the lens system is used. The overall length of the lens has been shortened to improve portability.

In the present invention, the aperture stop is disposed closer to the object side than the fifth lens unit, and the lens position is changed from a wide-angle end state (a state where the focal length is shortest) to a telephoto end state (a state where the focal length is longest). When the state changes, the distance between the aperture stop and the fifth lens group is reduced, and the fifth lens group is moved to the object side. At this time, by narrowing the distance between the aperture stop and the fifth lens group, the off-axis light beam passing through the negative lens group moves away from the optical axis in the wide-angle end state and approaches the optical axis in the telephoto end state. Further, by moving the fifth lens group toward the object side, the lateral magnification of the fifth lens group increases in the telephoto end state compared to the wide-angle end state, and the focal length changes. By the above two effects, in the present invention, the fluctuation of off-axis aberration generated due to the change of the lens position state is corrected well, and a high zoom ratio is realized.

However, if the back focus in the wide-angle end state is too long, the fluctuation of off-axis aberration due to a change in the angle of view cannot be satisfactorily corrected. Conversely, if the back focus is too short, the image plane of the fifth lens unit will be closer to the image plane. The dust shadow adhering to the surface is recorded on the film together with the subject image. Therefore, it is desirable that the back focus in the wide-angle end state be an appropriate value.

Further, in the present invention, in order to reduce the total length of the lens in the telephoto end state, a positive refractive power is given to the first lens group disposed closest to the object side of the lens system, and the telephoto end state and the wide-angle end state are provided. The first variable interval is widened as compared with. Conversely, in the wide-angle end state, the first variable interval is narrower than in the telephoto end state, and the first lens group is arranged closer to the image plane than in the telephoto end state, so that the axis passing through the first lens group is reduced. The external light flux is brought close to the optical axis to suppress negative curvature of field generated in the first lens group.

Further, in order to secure a sufficient back focus in the wide-angle end state and to satisfactorily correct the positive distortion, the third variable interval is widened. When the lens position state changes from the wide-angle end state to the telephoto end state, the third variable interval is narrowed to reduce the diverging effect of the second lens unit and the third lens unit, thereby shortening the overall lens length. In general, a lens-integrated camera uses a lens barrel structure in which a plurality of partial lens barrels are connected in a nested manner.In order to improve the portability of the camera, the thickness of the lens barrel is thinnest when carried. Is stored in the main body.

Therefore, the thickness of the camera body is reduced,
To improve portability, it is desirable to reduce the lens thickness of the taking lens system, and more specifically, it is desirable to configure the lens system with a small number of lenses. By the way, in order to realize a high zoom ratio, it is important to satisfactorily correct the fluctuation of the on-axis aberration and the fluctuation of the off-axis aberration generated according to the change of the lens position state. In order to properly correct the fluctuation of the axial aberration, it is necessary to satisfactorily correct the axial aberration generated for each lens group. Placement is important.

The lens group arranged near the aperture stop causes less off-axis aberration since the off-axis light beam passes near the optical axis, and is suitable for correcting axial aberration. Conversely, a lens group far from the aperture stop is more likely to generate off-axis aberration than on-axis aberration since the off-axis light beam passes away from the optical axis, and is suitable for correcting on-axis aberration. In the present invention, an aperture stop is arranged between the second lens group and the fourth lens group. At this time, the off-axis light flux passing through the second to fourth lens groups regardless of the lens position state passes near the optical axis.
The second to fourth lens groups mainly correct the axial aberration. Further, when the lens position changes from the wide-angle end state to the telephoto end state, the off-axis light beam passing through the first lens group approaches the optical axis, and the off-axis light beam passing through the fifth lens group approaches the optical axis. Therefore, the first lens group and the fifth lens group satisfactorily correct the fluctuation of off-axis aberration generated according to the change of the lens position. Therefore, by arranging the aperture stop in this way, it is possible to achieve both high zoom ratio and high performance.

Further, in the present invention, by integrally moving the second lens unit and the fourth lens unit, the performance deterioration due to mutual eccentricity, which tends to occur in the conventional positive / negative / positive / negative four-unit configuration type, is alleviated. To ensure stable optical performance. In the present invention, the following conditional expression (1) is satisfied.
It is desirable to satisfy Conditional expression (1) is a conditional expression that defines the thickness of the second to fourth lens units.

When the value of the conditional expression (1) exceeds the upper limit value, an off-axis light beam passing through the second lens unit or the fourth lens unit in the wide-angle end state is too far from the optical axis, and is generated at the periphery of the screen. Coma cannot be satisfactorily corrected. Conversely, when the value is below the lower limit, the refractive power of each of the lens units constituting the second lens unit and the fourth lens unit is increased, and the correction of the axial aberration generated in each lens unit becomes insufficient. Regardless of the state, it becomes difficult to maintain high optical performance.

Next, in the present invention, in order to obtain better optical performance while reducing the size of the lens system, it is desirable to satisfy at least one of the following conditional expressions (2) and (3). . (2) 0.3 <Da / f1 <0.5 (3) 1.0 <Db / | f5 | <1.3 where Da: from the most object side lens surface of the first lens unit in the telephoto end state Length along the optical axis up to the aperture stop f1: Focal length of the first lens group Db: Length along the optical axis from the aperture stop in the wide-angle end state to the most image-side lens surface of the fifth lens group f5 : Focal length of the fifth lens group Conditional expression (2) is a conditional expression for miniaturizing the lens system.

When the value of the conditional expression (2) exceeds the upper limit value, the off-axis light beam passing through the first lens unit at the telephoto end state is separated from the optical axis, and a large amount of coma aberration occurs at the periphery of the screen. Resulting in. Conversely, when the value is below the lower limit, the overall length of the lens in the telephoto end state increases. Conditional expression (3) is a condition for obtaining high optical performance in the wide-angle end state while miniaturizing the lens system.

If the value of the conditional expression (3) exceeds the upper limit, the off-axis light beam passing through the fifth lens unit is separated from the optical axis, which causes an increase in the lens diameter. vice versa,
When the value is below the lower limit, the difference in height between the on-axis light beam and the off-axis light beam passing through the fifth lens group is small, and the fluctuation of off-axis aberration due to the change in the angle of view cannot be satisfactorily corrected. By the way, as a short-distance focusing method of the variable focal length lens system, an FF (front focus) method, an IF (inner focus) method, and an RF (rear focus) method are known.

In the present invention, the off-axis light beam passing through the first lens unit and the fifth lens unit is separated from the optical axis in order to satisfactorily correct off-axis aberrations. In this case, the amount of work of the drive system increases, and the size of the drive system increases. Therefore, using these groups for focusing is not suitable for reducing the size of the camera body. In contrast,
Since the third lens group is disposed near the aperture stop, the lens diameter is small, and the work amount of the drive system and the size thereof are small, so that the third lens group is suitable for the focusing group. In this case, since the off-axis light beam passes near the optical axis, there is also an advantage that fluctuation of off-axis aberration generated at the time of short-distance focusing is small. Therefore, in the present invention, it is desirable to move the third lens group when focusing on a short distance.

Then, in the present invention, the third
In order to reduce the amount of movement of the lens unit for short-distance focusing and achieve further miniaturization, it is desirable that the following conditional expressions (4) and (5) are simultaneously satisfied. (4) β3t ** 2 <0.33 (5) β3w ** 2 <0.3 where β3t: lateral magnification of the third lens group in the telephoto end state β3w: of the third lens group in the wide-angle end state When the value of the conditional expression (4) exceeds the upper limit value, the amount of movement of the third lens group for focusing on a short distance becomes large.
If the value of the conditional expression (5) exceeds the upper limit value, particularly in the wide-angle end state, the amount of movement required for short-distance focusing of the third lens unit increases.

Next, in the present invention, it is desirable to satisfy the following conditional expression (6) in order to reduce the total length of the lens in the telephoto end state. (6) β3t <0 When the lateral magnification of the third lens unit is negative, the first lens unit and the second lens unit
When the lateral power of the third lens group is positive, the composite refractive power of the first lens group and the second lens group is negative. In order to reduce the overall length of the lens in the telephoto end state, it is desirable that the combined refractive power of the first lens group and the second lens group is positive. Therefore,
If the value of conditional expression (6) exceeds the upper limit, the overall length of the lens in the telephoto end state increases.

Next, in the present invention, it is desirable to satisfy the following conditional expression (7) in order to reduce the size of the lens system and achieve higher performance. (7) 0.008 <ΔD2 / ｛(fw · ft) ** 0.5
Z｝ <0.02 ΔD2: The size of the second variable interval in the wide-angle end state is D2w,
When the magnitude of the second variable interval in the telephoto end state is D2t, the quantity defined by the following equation is ΔD2 = D2t−D2w fw: focal length in the wide-angle end state ft: focal length Z in the telephoto end state The zoom ratio Z = ft / fw defined by the following expression: Conditional expression (7) is a conditional expression that defines the amount of change in the second variable interval. The miniaturization cannot be achieved. Conversely, when the value falls below the lower limit, the amount of change in the lateral magnification of the fifth lens unit in the wide-angle end state and the telephoto end state becomes extremely large, and the fluctuation of off-axis aberration due to the change in the lens position state is favorably corrected. It is not possible to achieve higher performance.

In the present invention, as described above, it is desirable to move the third lens group at the time of short-distance focusing, but it is preferable to move the fifth lens group or to integrate the second to fourth lens groups. It is also possible to perform short-distance focusing by moving to. In addition, by shifting the entire lens group or a part of the lens group constituting the lens system in a direction substantially perpendicular to the optical axis,
It is also possible to shift the image. In particular, the camera functions as a so-called anti-shake optical system by combining a detection system for detecting camera shake, a drive system for shifting the lens group, and a control system for calculating a drive amount given to the drive system in accordance with an output from the detection system. It is also possible.

Furthermore, it is naturally possible to reduce the weight and cost by introducing a plastic material, or to reduce the number of lens components or increase the zoom ratio by introducing an aspheric surface. .

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments according to the present invention will be described below. FIG. 1 shows the refractive power distribution in each embodiment of the present invention. This refractive power distribution is common to all the embodiments. In order from the object side, a first lens group G having a positive refractive power
1, a second lens group G having a negative refractive power, a third lens group G3 having a negative refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power. During zooming to the end state, the air gap between the first lens group G1 and the second lens group G2 increases, and the second lens group G2 and the third
The air gap with the lens group G3 decreases, and the third lens group G3
All the lens units move so that the air gap between the fourth lens group G4 and the fourth lens group G4 decreases, and the air gap between the fourth lens group G4 and the fifth lens group G5 decreases.

In each embodiment, the aspheric surface is represented by the following equation. x = cy ** 2 / ｛1+ (1-κc ** 2 · y ** 2) ** 0.
5｝ + C4y ** 4 + C6y ** 6 + ... y is the height from the optical axis, x is the amount of sag, c is the curvature, κ
Is a conical constant, and C4, C6,... Are aspherical coefficients.

[0030]

FIG. 2 shows the structure of a lens according to a first embodiment of the present invention. In the first embodiment, the first lens group G1 is composed of a cemented positive lens L1 composed of a biconvex lens and a meniscus-shaped negative lens having a concave surface facing the object side, in order from the object side. G2 is composed of a biconcave lens L21 and a biconvex lens L22, the third lens group G3 is composed of a negative meniscus lens L3 having a concave surface facing the object side, and the fourth lens group G4 is composed of a biconvex lens and an object. The fifth lens group G5 includes a cemented positive lens L41 composed of a meniscus negative lens with a concave surface facing the image side, and a meniscus positive lens L42 with a convex surface facing the image side. It comprises a meniscus-shaped positive lens L51 having a concave surface and a meniscus-shaped negative lens L52 having a concave surface facing the object side.

When the lens position changes from the wide-angle end state to the telephoto end state, the second lens unit and the fourth lens unit move integrally, and the aperture stop S moves to the third lens unit G3. , And is moved between the lens unit and the fourth lens unit G4. Further, the third lens group G3 moves to the object side when focusing on a short distance. Table 1 below shows values of specifications of the first embodiment of the present invention. In the specifications of the embodiment, f is the focal length, FNO is the F number, 2ω is the angle of view, and the refractive index is a value for the d-line (λ = 587.6 nm).

[0032]

[Table 1] The fifteenth and sixteenth surfaces are aspherical surfaces, and the respective coefficients are as follows. [Stage 15] κ = 1.0000 C4 = + 2.3514 × 10 **-4 C6 = + 1.1554 × 10 **-6 C8 = + 2.8070 × 10 **-9 C10 = 0 [Sixteenth surface] κ = 1.0000 C4 = +7.1525 x 10 **-5 C6 = -7.9405 x 10 **-7 C8 = +1.8901 x 10 **-8 C10 = -1.07995 x 10 **-10 [Variable interval table] f 25.7500 48.0000 96.9989 D3 1.2000 6.4554 13.9055 D7 1.5479 2.5348 4.1739 D9 3.6260 2.6391 1.0000 D15 10.0377 4.6360 1.2762 Bf 8.0491 24.6999 51.7936 [Focusing travel amount Δ2 of second lens group (photography magnification -1 / 40x from ∞)] f 25.7500 48.0000 96.9989 Δ3 0.6570 0.4655 0.3788 [Conditions] Expression-corresponding value] f1 = 74.0520 f5 = -19.5248 β3t = −0.4142 β3w = −0.2904 (1) ｆD24 / fw = 0.597 (2) Da / f1 = 0.368 (3) Db / | f5 | = 1. 121 (4) β3t ** 2 = 0.172 (5) β3w ** 2 = 0.084 (6) β3t = −0.414 (7) ΔD2 / ｛(fw · ft) ** 0.5 · ｝ = 0.014 FIGS. 3 to 8 show various aberration diagrams of the first embodiment of the present invention. FIGS. 3 to 5 show a state of focusing on infinity, and FIGS. FIGS. 3 and 6 show various aberration diagrams in a distance in-focus state (photographing magnification -1/40), and FIGS. 3 and 6 show a wide-angle end state (f = 25.75), and FIGS. 4 and 7 show an intermediate focus. FIGS. 5 and 8 show various aberration diagrams in the telephoto end state (f = 97.0) in the distance state (f = 48.0).

In each of the aberration diagrams of FIGS. 3 to 8, the solid line in the spherical aberration diagram indicates the spherical aberration, the dotted line indicates the sine condition, y indicates the image height, and the solid line in the astigmatism diagram indicates the sagittal. An image plane and a broken line indicate a meridional image plane, and d indicates an aberration with respect to the d-line. The coma aberration diagram shows the coma aberration at the image height y = 0, 4.3, 8.6, 12.04, 17.2, A indicates the angle of view, and H indicates the object height.

From each aberration diagram, it is clear that the present embodiment has excellent correction of various aberrations and excellent imaging performance.

[0035]

FIG. 9 shows the structure of a lens according to a second embodiment of the present invention. In the second embodiment, the first lens group G1 is composed of a cemented positive lens L1 composed of a biconvex lens and a meniscus-shaped negative lens having a concave surface facing the object side in order from the object side. G2 is composed of a biconcave lens L21 and a biconvex lens L22, the third lens group G3 is composed of a negative meniscus lens L3 having a concave surface facing the object side, and the fourth lens group G4 is composed of a biconvex lens and an object. The fifth lens group G5 includes a cemented positive lens L41 composed of a meniscus negative lens with a concave surface facing the image side, and a meniscus positive lens L42 with a convex surface facing the image side. It comprises a meniscus-shaped positive lens L51 having a concave surface and a meniscus-shaped negative lens L52 having a concave surface facing the object side.

When the lens position changes from the wide-angle end state to the telephoto end state, the second lens group and the fourth lens group move integrally, and the aperture stop S moves to the third lens group G3. , And is moved between the lens unit and the fourth lens unit G4. Further, the third lens group G3 moves to the object side when focusing on a short distance. Table 2 below shows values of specifications of the second embodiment of the present invention. In the specifications of the embodiment, f is the focal length, FNO is the F number, 2ω is the angle of view, and the refractive index is a value for the d-line (λ = 587.6 nm).

[0037]

[Table 2] The fifteenth and sixteenth surfaces are aspherical surfaces, and the respective coefficients are as follows. [Stage 15] κ = 1.0000 C4 = + 2.2018 × 10 ** − 4 C6 = + 1.5666 × 10 ** − 6 C8 = −5.7457 × 10 ** − 9 C10 = 0 [Sixteenth surface] κ = 1.0000 C4 = + 6.1316 × 10 **-5 C6 = -7.2005 × 10 **-7 C8 = + 2.0267 × 10 **-8 C10 = -1.4196 × 10 **-10 [Variable interval table] f 25.7500 48.0000 96.9995 D3 1.2000 5.4965 10.3224 D7 1.3937 2.4403 3.9000 D9 3.5062 2.4598 1.0000 D15 10.1318 4.7577 1.2504 Bf 8.0491 24.6999 51.7936 [The focusing movement amount Δ3 of the third lens group (from ∞ to the magnification of -1/40)] f 25.7500 48.0000 96.9995 Δ3 0.6734 0.4817 0.3585 [Conditions] Expression-corresponding value] f1 = 65.0612 f5 = -19.5463 β3t = −0.5508 β3w = −0.4018 (1) ｆD24 / fw = 0.600 (2) Da / f1 = 0.372 (3) Db / | f5 | = 1. 137 (4) β3t ** 2 = 0.303 (5) β3w ** 2 = 0.161 (6) β3t = −0.551 (7) ΔD2 / ｛(fw · ft) ** 0. · Z} = 0.013 Figure 10 to Figure 15 show various aberration diagrams of a second embodiment of the present invention, FIG. 10 through FIG. 12 infinity in-focus state, the first
FIG. 3 to FIG. 15 show a short-distance in-focus state (photographing magnification -４).
FIGS. 10 and 13 show a wide-angle end state (f = 25.75), FIGS. 11 and 14 show an intermediate focal length state (f = 48.0), and FIGS. First
2 and 15 show various aberration diagrams in the telephoto end state (f = 97.0).

In each of the aberration diagrams in FIGS. 10 to 15, the solid line in the spherical aberration diagram indicates the spherical aberration, the dotted line indicates the sine condition, y indicates the image height, and the solid line in the astigmatism diagram indicates the sagittal. An image plane and a broken line indicate a meridional image plane, and d indicates an aberration with respect to the d-line. The coma diagram is
A coma aberration at an image height y = 0, 4.3, 8.6, 12.04, 17.2 is shown, A indicates an angle of view, and H indicates an object height.

From each aberration diagram, it is clear that this embodiment has excellent correction of various aberrations and excellent imaging performance.

[0040]

Third Embodiment FIG. 16 shows the structure of a lens according to a third embodiment of the present invention. In the third embodiment, in order from the object side, the first lens group G1 includes a cemented positive lens L1 including a biconvex lens and a meniscus-shaped negative lens having a concave surface facing the object side, and the second lens group. G2 is composed of a biconcave lens L21 and a biconvex lens L22, the third lens group G3 is composed of a negative meniscus lens L3 having a concave surface facing the object side, and the fourth lens group G4 is composed of a biconvex lens and an object. A cemented positive lens L41 composed of a meniscus negative lens with a concave surface facing the side, and a biconvex lens L42
The fifth lens group G5 includes a meniscus-shaped positive lens L51 having a concave surface facing the object side and a meniscus-shaped negative lens L52 having a concave surface facing the object side.

When the lens position changes from the wide-angle end state to the telephoto end state, the second lens group and the fourth lens group move integrally, and the aperture stop S moves to the third lens group G3. , And is moved between the lens unit and the fourth lens unit G4. Further, the third lens group G3 moves to the object side when focusing on a short distance. Table 3 below shows values of specifications of the third embodiment of the present invention. In the specifications of the embodiment, f is the focal length, FNO is the F number, 2ω is the angle of view, and the refractive index is a value for the d-line (λ = 587.6 nm).

[0042]

[Table 3] The fifteenth and sixteenth surfaces are aspherical surfaces, and the respective coefficients are as follows. [Stage 15] κ = 1.0000 C4 = + 1.6930 × 10 ** − 4 C6 = + 1.7164 × 10 ** − 6 C8 = −2.2228 × 10 ** − 8 C10 = 0 [Sixteenth surface] κ = 1.0000 C4 = + 6.4088 × 10 **-5 C6 = -2.7213 × 10 **-7 C8 = + 1.4552 × 10 **-8 C10 = -4.3685 × 10 **-11 [Variable interval table] f 25.7500 48.0000 97.0002 D3 1.2000 7.7530 15.5626 D7 1.5150 2.5103 3.9000 D9 3.3850 2.3897 1.0000 D15 11.3761 5.5357 1.3002 Bf 6.7915 22.6285 50.1375 [Focusing movement amount Δ3 of the third lens group (from ∞ to magnification -1/40)] f 25.7500 48.0000 97.0002 Δ3 0.7607 0.5897 0.5239 [Conditions] Expression-corresponding value] f1 = 66.80441 f5 = -19.90200 β3t = −0.3604 β3w = −0.1916 (1) ΣD24 / fw = 0.588 (2) Da / f1 = 0.436 (3) Db / | f5 | = 1. 195 (4) β3t ** 2 = 0.130 (5) β3w ** 2 = 0.037 (6) β3t = −0.360 (7) ΔD2 / ｛(fw · ft) ** 0.5 · FIG. 17 to FIG. 22 show various aberration diagrams of the third embodiment of the present invention. FIG. 17 to FIG.
FIG. 0 to FIG. 22 show a short-distance in-focus state (photographing magnification -−１).
FIGS. 17 and 20 show the aberration diagrams at the wide-angle end state (f = 25.75), FIGS. 18 and 21 show the intermediate focal length state (f = 48.0), respectively. First
9 and 22 show various aberration diagrams in the telephoto end state (f = 97.0).

In each of the aberration diagrams in FIGS. 17 to 22, the solid line in the spherical aberration diagram indicates the spherical aberration, the dotted line indicates the sine condition, y indicates the image height, and the solid line in the astigmatism diagram indicates the sagittal An image plane and a broken line indicate a meridional image plane, and d indicates an aberration with respect to the d-line. The coma diagram is
A coma aberration at an image height y = 0, 4.3, 8.6, 12.04, 17.2 is shown, A indicates an angle of view, and H indicates an object height.

From each aberration diagram, it is clear that this embodiment has excellent correction of various aberrations and excellent imaging performance.

[0045]

Fourth Embodiment FIG. 23 shows the structure of a lens according to a fourth embodiment of the present invention. In the fourth embodiment, in order from the object side, the first lens group G1 is composed of a cemented positive lens L1 composed of a biconvex lens and a meniscus-shaped negative lens having a concave surface facing the object side, and the second lens group G2 Is composed of a biconcave lens L21 and a biconvex lens L22, the third lens group G3 is composed of a meniscus-shaped negative lens L3 having a concave surface facing the object side, and the fourth lens group G4 is composed of a biconvex lens and the object side The fifth lens group G5 includes a cemented positive lens L41 composed of a meniscus-shaped negative lens with a concave surface facing the lens, and a meniscus-shaped positive lens L42 with a convex surface facing the image side. And a meniscus-shaped negative lens L52 having a concave surface facing the object side.

When the lens position changes from the wide-angle end state to the telephoto end state, the second lens group and the fourth lens group move integrally, and the aperture stop S moves to the third lens group G3. , And is moved between the lens unit and the fourth lens unit G4. Further, the third lens group G3 moves to the object side when focusing on a short distance. Table 4 below shows data values of the fourth embodiment of the present invention. In the specifications of the embodiment, f is the focal length, FNO is the F number, 2ω is the angle of view, and the refractive index is a value for the d-line (λ = 587.6 nm).

[0047]

[Table 4] The fifteenth and sixteenth surfaces are aspherical surfaces, and the respective coefficients are as follows. [Stage 15] κ = 1.0000 C4 = + 1.8115 × 10 ** − 4 C6 = + 1.1583 × 10 ** − 6 C8 = −4.3346 × 10 ** − 9 C10 = 0 [Sixteenth surface] κ = 1.0000 C4 = + 5.1858 × 10 **-5 C6 = + 6.3539 × 10 **-8 C8 = + 2.3417 × 10 **-9 C10 = + 2.3927 × 10 **-11 [Variable interval table] f 25.7499 47.9995 96.9981 D3 1.2000 7.5020 15.6220 D7 1.4339 2.4213 3.9000 D9 3.4661 2.4787 1.0000 D15 11.1817 5.3353 1.2500 Bf 6.8777 23.0039 50.0773 [Focusing movement amount Δ3 of the third lens group (from 倍率 to magnification -1/40)] f 25.7499 47.9995 96.9981 Δ3 0.7081 0.5327 0.4674 [Conditions] Expression-corresponding value] f1 = 68.5028 f5 = -20.1016 β3t = −0.3487 β3w = −0.1931 (1) ｆD24 / fw = 0.594 (2) Da / f1 = 0.423 (3) Db / | f5 | = 1. 188 (4) β3t ** 2 = 0.122 (5) β3w ** 2 = 0.037 (6) β3t = −0.349 (7) ΔD2 / ｛(fw · ft) ** 0.5 · } = 0.013 Figure 24 to Figure 29 are graphs showing various aberrations of the fourth embodiment of the present invention, FIG. 24 through FIG. 26 infinity in-focus state, the second
FIG. 7 to FIG. 29 show a short-distance in-focus condition (photographing magnification -−１).
FIGS. 17 and 20 show the aberration diagrams at the wide-angle end state (f = 25.75), FIGS. 18 and 21 show the intermediate focal length state (f = 48.0), respectively. First
9 and 22 show various aberration diagrams in the telephoto end state (f = 97.0).

24 to 29, the solid line in the spherical aberration diagram indicates the spherical aberration, the dotted line indicates the sine condition, y indicates the image height, and the solid line in the astigmatism diagram indicates the sagittal. An image plane and a broken line indicate a meridional image plane, and d indicates an aberration with respect to the d-line. The coma diagram is
A coma aberration at an image height y = 0, 4.3, 8.6, 12.04, 17.2 is shown, A indicates an angle of view, and H indicates an object height.

From each aberration diagram, it is clear that this embodiment has excellent correction of various aberrations and excellent imaging performance.

[0050]

Fifth Embodiment FIG. 30 shows the structure of a lens according to a fifth embodiment of the present invention. In the fifth embodiment, in order from the object side, the first lens group G1 includes a cemented positive lens L1 including a biconvex lens and a meniscus-shaped negative lens having a concave surface facing the object side, and the second lens group G2. Is composed of a biconcave lens L21 and a meniscus-shaped positive lens L22 having a convex surface facing the object side, the third lens group G3 is composed of a biconcave lens L3, and the fourth lens group G4 is composed of a biconvex lens and the object side. The fifth lens unit G5 includes a cemented positive lens L41 composed of a concave meniscus negative lens and a biconvex lens L42. The fifth lens group G5 includes a meniscus positive lens L51 concave on the object side and an object side. And a meniscus-shaped negative lens L52 having a concave surface facing the lens.

When the lens position changes from the wide-angle end state to the telephoto end state, the second lens unit and the fourth lens unit move integrally, and the aperture stop S moves to the third lens unit G3. , And is moved between the lens unit and the fourth lens unit G4. Further, the third lens group G3 moves to the object side when focusing on a short distance. Table 5 below shows data values of the fifth embodiment of the present invention. In the specifications of the embodiment, f is the focal length, FNO is the F number, 2ω is the angle of view, and the refractive index is a value for the d-line (λ = 587.6 nm).

[0052]

[Table 5] The fifteenth and sixteenth surfaces are aspherical surfaces, and the respective coefficients are as follows. [Stage 15] κ = 1.0000 C4 = + 1.6672 × 10 **-4 C6 = + 8.0731 × 10 **-7 C8 = + 3.4735 × 10 **-9 C10 = 0 [Sixteenth surface] κ = 1.0000 C4 = + 2.8813 × 10 **-5 C6 = + 3.9311 × 10 **-8 C8 = + 1.3102 × 10 **-9 C10 = -6.7084 × 10 **-12 [Variable interval table] f 25.7499 47.9998 96.9981 D3 1.0000 8.1470 16.0488 D7 1.4980 2.2872 3.7000 D9 3.2018 2.4128 1.0000 D15 11.8229 5.3998 1.2500 Bf 6.2300 22.5576 49.6503 [Focusing movement amount Δ3 of the third lens group (from 倍率 to magnification × 1/40)] f 25.7499 47.9998 96.9981 Δ3 0.5370 0.4069 0.3327 [Conditions] Expression corresponding value] f1 = 71.9909 f5 = −21.4299 β3t = −0.3304 β3w = −0.22011 (1) ΣD24 / fw = 0.586 (2) Da / f1 = 0.388 (3) Db / | f5 | = 1. 184 (4) β3t ** 2 = 0.109 (5) β3w ** 2 = 0.040 (6) β3t = −0.330 (7) ΔD2 / ｛(fw · ft) ** 0.5 · } = 0.012 FIG. 31 through FIG. 26 shows the various aberrations of the fifth embodiment of the present invention, FIG. 31 through FIG. 33 infinity in-focus state, the third
FIG. 4 to FIG. 36 show a short-distance in-focus state (photographing magnification -−１).
FIG. 31 and FIG. 34 show the wide-angle end state (f = 25.75), FIG. 32 and FIG. 35 show the intermediate focal length state (f = 48.0), respectively. Third
3 and 36 show various aberration diagrams in the telephoto end state (f = 97.0).

31 to 36, the solid line in the spherical aberration diagram indicates spherical aberration, the dotted line indicates sine condition, y indicates image height, and the solid line in astigmatism diagram indicates sagittal. An image plane and a broken line indicate a meridional image plane, and d indicates an aberration with respect to the d-line. The coma diagram is
A coma aberration at an image height y = 0, 4.3, 8.6, 12.04, 17.2 is shown, A indicates an angle of view, and H indicates an object height.

From each aberration diagram, it is clear that this embodiment has excellent correction of various aberrations and excellent imaging performance.

[0055]

Sixth Embodiment FIG. 37 is a diagram showing the configuration of a lens according to a sixth embodiment of the present invention. In the sixth embodiment, in order from the object side, the first lens group G1 is composed of a cemented positive lens L1 composed of a biconvex lens and a meniscus-shaped negative lens whose concave surface faces the object side, and the second lens group G2 Is composed of a biconcave lens L21 and a meniscus-shaped positive lens L22 having a convex surface facing the object side, the third lens group G3 is composed of a biconcave lens L3, and the fourth lens group G4 is composed of a biconvex lens and the object side. The fifth lens unit G5 includes a cemented positive lens L41 composed of a concave meniscus negative lens and a biconvex lens L42. The fifth lens group G5 includes a meniscus positive lens L51 concave on the object side and an object side. And a meniscus-shaped negative lens L52 having a concave surface facing the lens.

When the lens position changes from the wide-angle end state to the telephoto end state, the second lens unit and the fourth lens unit move integrally, and the aperture stop S moves to the third lens unit G3. , And is moved between the lens unit and the fourth lens unit G4. Further, the third lens group G3 moves to the object side when focusing on a short distance. Table 6 below shows values of specifications of the sixth embodiment of the present invention. In the specifications of the embodiment, f is the focal length, FNO is the F number, 2ω is the angle of view, and the refractive index is a value for the d-line (λ = 587.6 nm). The fifteenth and sixteenth surfaces are aspherical surfaces, and the respective coefficients are as follows. [Stage 15] κ = -1.77771 C4 = + 1.6672 × 10 **-4 C6 = + 8.0731 × 10 **-7 C8 = + 3.4735 × 10 **-9 C10 = 0 [Sixteenth] κ =- 0.3626 C4 = +4.0334 x 10 **-5 C6 = +2.8306 x 10 **-7 C8 = -2.3569 x 10 **-9 C10 = +5.3286 x 10 **-11 [Variable interval table] f 25.7497 47.9991 96.9968 D3 1.0000 8.7806 16.7567 D7 1.5678 2.1497 3.6000 D9 3.0322 2.4503 1.0000 D15 11.4161 5.1625 1.2500 Bf 6.2998 22.2997 48.7913 [Focusing movement amount Δ3 of the third lens group (from ∞-photographing magnification -1 / 40x)] f 25.7497 47.9991 96.9968 Δ3 0.5909 0.4596 0.3800 [Values corresponding to conditional expressions] f1 = 71.8760 f5 = -20.1652 β3t = -0.3128 β3w = -0.1736 (1) ΣD24 / fw = 0.596 (2) Da / f1 = 0.396 (3) Db / | f5 | = 1.246 (4) β3t ** 2 = 0.098 (5) β3w ** 2 = 0.030 (6) β3t = -0.313 (7) ΔD2 / ｛(fw · ft) ** 0.5 · Z = 0.011 FIG. 38 through FIG. 43 shows the various aberrations of the sixth embodiment of the present invention, FIG. 38 through FIG. 40 infinity in-focus condition, the fourth
FIGS. 1 to 43 show a short-distance focusing state (photographing magnification -−１).
FIGS. 38 and 41 show a wide-angle end state (f = 25.75), FIGS. 39 and 42 show an intermediate focal length state (f = 48.0), and FIGS. 4th
FIG. 0 and FIG. 43 show various aberration diagrams in the telephoto end state (f = 97.0).

38 to 43, the solid line in the spherical aberration diagram indicates spherical aberration, the dotted line indicates sine condition, y indicates image height, and the solid line in astigmatism diagram indicates sagittal. An image plane and a broken line indicate a meridional image plane, and d indicates an aberration with respect to the d-line. The coma diagram is
A coma aberration at an image height y = 0, 4.3, 8.6, 12.04, 17.2 is shown, A indicates an angle of view, and H indicates an object height.

From the aberration diagrams, it is clear that the present embodiment has excellent correction of various aberrations and excellent imaging performance.

[0059]

According to the present invention, it is possible to realize a zoom lens having a small number of lenses and capable of increasing the zoom ratio.

[Brief description of the drawings]

FIG. 1 is a diagram showing a refractive power arrangement of a zoom lens according to the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a zoom lens according to a first embodiment.

FIG. 3 is an aberration diagram of the first embodiment in a wide-angle end state (focused on infinity).

FIG. 4 is an aberration diagram of the first embodiment in an intermediate focal length state (focused on infinity).

FIG. 5 is an aberration diagram of the first embodiment in a telephoto end state (focused on infinity).

FIG. 6 is an aberration diagram of the first embodiment in a wide-angle end state (focused on a short distance).

FIG. 7 is an aberration diagram of the first embodiment in an intermediate focal length state (short-distance in-focus state).

FIG. 8 is an aberration diagram of the first embodiment in a telephoto end state (short-distance in-focus state).

FIG. 9 is a sectional view showing a configuration of a zoom lens according to a second embodiment.

FIG. 10 is an aberration diagram of the second embodiment in a wide-angle end state (focused on infinity).

FIG. 11 is an aberration diagram of the second embodiment in an intermediate focal length state (focused on infinity).

FIG. 12 is an aberration diagram of the second embodiment in a telephoto end state (focused on infinity).

FIG. 13 is an aberration diagram of the second embodiment in a wide-angle end state (short-distance in-focus state).

FIG. 14 is an aberration diagram of the second embodiment in an intermediate focal length state (short-distance in-focus state)

FIG. 15 is an aberration diagram of the second embodiment in a telephoto end state (short-distance in-focus state).

FIG. 16 is a sectional view showing the configuration of a zoom lens according to a third embodiment.

FIG. 17 is an aberration diagram of the third embodiment in a wide-angle end state (focused on infinity).

FIG. 18 is an aberration diagram of the third embodiment in an intermediate focal length state (focused on infinity).

FIG. 19 is an aberration diagram of the third embodiment in a telephoto end state (focused on infinity).

FIG. 20 is an aberration diagram of the third embodiment in a wide-angle end state (focused on a short distance).

FIG. 21 is an aberration diagram of the third embodiment in an intermediate focal length state (short-distance in-focus state).

FIG. 22 is an aberration diagram of the third embodiment in a telephoto end state (short-distance in-focus state).

FIG. 23 is a sectional view showing the configuration of a zoom lens according to a fourth embodiment.

FIG. 24 is an aberration diagram of a fourth embodiment in a wide-angle end state (focused on infinity).

FIG. 25 is an aberration diagram of the fourth embodiment in an intermediate focal length state (focused on infinity).

FIG. 26 is an aberration diagram of the fourth embodiment in a telephoto end state (focused on infinity).

FIG. 27 is an aberration diagram of the fourth embodiment in a wide-angle end state (focused on a short distance).

FIG. 28 is an aberration diagram of the fourth embodiment in an intermediate focal length state (short-distance in-focus state);

FIG. 29 is an aberration diagram in a telephoto end state of the fourth embodiment (short-distance in-focus state)

FIG. 30 is a sectional view showing the configuration of a zoom lens according to a fifth embodiment.

FIG. 31 is an aberration diagram of a fifth embodiment in a wide-angle end state (focused on infinity).

FIG. 32 is an aberration diagram of the fifth embodiment in an intermediate focal length state (focused on infinity).

FIG. 33 is an aberration diagram at a telephoto end in a fifth embodiment (focused on infinity);

FIG. 34 is an aberration diagram of the fifth embodiment in a wide-angle end state (focused on a short distance).

FIG. 35 is an aberrational diagram of the fifth embodiment in an intermediate focal length state (short-distance in-focus state)

FIG. 36 is an aberration diagram of the fifth embodiment in a telephoto end state (short-distance in-focus state);

FIG. 37 is a sectional view showing the configuration of a zoom lens according to a sixth embodiment.

FIG. 38 is an aberration diagram of the sixth embodiment in a wide-angle end state (focused on infinity).

FIG. 39 is an aberration diagram at an intermediate focal length in a sixth embodiment (focused on infinity);

FIG. 40 is an aberration diagram at a telephoto end in the sixth embodiment (focused on infinity);

FIG. 41 is an aberration diagram of the sixth embodiment in a wide-angle end state (focused on a short distance).

FIG. 42 is an aberration diagram of the sixth embodiment in an intermediate focal length state (short-distance in-focus state);

FIG. 43 is an aberration diagram at a telephoto end of the sixth embodiment (focused on a short distance);

Claims (6)

[Claims] A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, a fourth lens group having a positive refractive power, and A fifth lens group having negative refracting power, wherein a first variable interval is formed between the first lens group and the second lens group, and a fifth lens group is formed between the second lens group and the third lens group. A second variable interval is formed between the third lens group and the fourth lens group, and a third variable interval is formed between the third lens group and the fourth lens group.
A fourth variable interval is formed between the lens group and the fifth lens group, and when the lens position changes from the wide-angle end state to the telephoto end state, the first variable interval increases and the second variable interval increases. All the lens groups move toward the object side so that the distance increases, the third variable distance decreases, and the fourth variable distance decreases, and the second lens group and the fourth lens group Are moved integrally, an aperture stop is arranged between the second lens group and the fourth lens group, and the following conditional expression (1) is satisfied: . (1) 0.5 <ΔD24 / fw <0.7 where ΔD24 is the length along the optical axis from the lens surface closest to the object in the second lens unit to the lens surface closest to the image in the fourth lens unit. . 2. The variable focal length lens system according to claim 1, wherein at least one of the following conditional expressions (2) and (3) is satisfied. (2) 0.3 <Da / f1 <0.5 (3) 1.0 <Db / | f5 | <1.3 where Da: from the most object side lens surface of the first lens unit in the telephoto end state Length along the optical axis up to the aperture stop f1: Focal length of the first lens unit Db: Length along the optical axis from the aperture stop in the wide-angle end state to the lens surface closest to the image of the fifth lens unit f5 : Focal length of the fifth lens group 3. The variable focal length lens system according to claim 1, wherein said third lens group moves in the direction of the optical axis during short-distance focusing, and satisfies the following conditional expression (4). And a variable focal length lens system. (4) β3t ** 2 <0.33 (in the formulas and hereinafter, the notation of a ** b represents a raised to the power of b.) Where β3t is the third lens group in the telephoto end state. Horizontal magnification 4. The variable focal length lens system according to claim 3, wherein the following conditional expression (5) is satisfied. (5) β3w ** 2 <0.3, where β3w: lateral magnification of the third lens unit in the wide-angle end state 5. The variable focal length lens system according to claim 4, wherein the following conditional expression (6) is satisfied. (6) β3t <0 6. The variable focal length lens system according to claim 1, wherein the following conditional expression (7) is satisfied. (7) 0.008 <ΔD2 / ｛(fw · ft) ** 0.5
Z｝ <0.02 where ΔD2 is D2w, the size of the second variable interval in the wide-angle end state.
When the magnitude of the second variable interval in the telephoto end state is D2t, the quantity defined by the following equation is ΔD2 = D2t−D2w fw: focal length in the wide-angle end state ft: focal length Z in the telephoto end state : Zoom ratio defined by the following equation: Z = ft / fw