JP2001059938A - Zoom lens with macro mode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens with a macro mode which is suitable to attain miniaturization and whose mechanism is simplified, even though the lens is provided with such the macro mode capable of focusing on a distance closer than a normal photographing range. SOLUTION: The zoom lens is constituted of a 1st group G11 having a positive focal length, a 2nd group G12 having a negative focal length, an open aperture S1, a 3rd group G13 having the positive focal length, a 4th group G14 having the positive focal lenght, and a parallel plate F1 made of various kinds of filters, and they are arranged on an optical axis from an object side in this order. As for a focusing operation of the zoom lens in the macro mode, the focusing operation is executed by moving the 4th group G14 in the same way as that at shot and long focal ends, and in this case, the 2nd group G12 is arranged closer to the image plane as compared with a position of the 2nd group G12 at the short focal end, and the 3rd group G13 is arranged so as to nearly align with the 3rd group 13 at the long focal end.

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 macro mode, and more particularly to a macro mode used as a zoom photographing lens used for a digital camera and a video camera, and further used as a zoom photographing lens used for a silver halide camera. And a zoom lens having the same.

[0002]

2. Description of the Related Art The market for digital cameras, which has been established due to the spread of personal computers (PCs), is becoming larger as infrastructure for printouts is being improved. Users' demands for digital cameras include high image quality, high magnification,
Weights such as miniaturization and power saving are significant, and it is necessary to develop digital cameras that meet these demands in the future. For this reason, a zoom lens has become the norm as a photographing lens, and it is required to achieve both high image quality, high zoom ratio, and miniaturization to support a light receiving element having more than 3 million pixels. Also, considering the usability of the user,
It is desirable to use a taking lens that can focus on a shorter distance. In this case, focusing at a short distance means that a high photographing magnification is secured and a smaller area can be photographed.

[0003] There are many types of zoom lenses for digital cameras.
In order from the object side, a first group having a positive focal length, a second group having a negative focal length, a third group having a positive focal length,
The zoom lens has a fourth lens unit having a positive focal length, and during zooming from the short focal length end to the long focal length end, the second lens unit moves monotonously from the object side to the image side due to zooming, and the third lens unit moves. There is a type that moves monotonously from the image side to the object side and performs focusing by moving the fourth unit. In this type, by providing an auxiliary zooming effect to the third lens group, the amount of movement of the second lens group during zooming can be reduced, and the distance from the first lens group to the aperture stop can be reduced. It is possible to reduce the diameter of one group of lenses. As this type of zoom lens, a "magnifying lens" described in JP-A-06-194572 and a "zoom lens" described in JP-A-10-062687 have been proposed.

[0004]

The above-mentioned Japanese Patent Application Laid-Open No. H06-1
In the “magnifying lens” described in Japanese Patent No. 94572,
At the short focal length end, focusing can be performed almost up to the front end of the lens. However, this is the third
This is because the distance between the group and the fourth group is sufficiently large when focusing to infinity, and the focusing movement amount can be easily secured. Therefore, if the size of the lens is reduced, especially the overall length is reduced, it is not always possible to secure a sufficient distance between the third and fourth units at the short focal length when focusing to infinity. The fact that focusing is performed by four groups does not always mean that focusing can be performed to the front end of the lens at the short focal length end.

Further, in the "zoom lens" described in Japanese Patent Application Laid-Open No. 10-062687, focusing to a short distance is performed by another method. That is, focusing in the normal photographing area is performed by moving the fourth group, and focusing to a shorter distance is performed by moving the second group in addition to the fourth group. But,
It is not preferable that there are a plurality of groups driven by a focus signal from a distance measuring unit or the like because the mechanism becomes complicated.

Accordingly, the present invention has been made in view of the above problems, and has a macro mode capable of focusing at a shorter distance than a normal photographing area, suitable for miniaturization, and having a simple mechanism. It is an object to provide a zoom lens having a mode.

[0007]

The above object is achieved by the following zoom lens having a macro mode according to the present invention. That is, the zoom lens having the macro mode according to claim 1 includes, in order from the object side, a first group having a positive focal length, a second group having a negative focal length, an aperture stop,
A third group having a positive focal length and a fourth group having a positive focal length
The second group, the third group, and the fourth group are movable, and the second group moves monotonously from the object side to the image side during zooming from the short focal length end to the long focal length end. The third lens group is a zoom lens that moves monotonously from the image side to the object side and performs focusing in a normal photographing area by moving the fourth lens group. The second lens group and the third lens group have a different positional relationship from that during zooming. And a macro mode in which focusing is performed at a shorter distance than the normal shooting area, and focusing in the macro mode is performed by moving the fourth group.

According to a second aspect of the present invention, there is provided a zoom lens having a macro mode, comprising, in order from the object side, a first lens unit having a positive focal length, a second lens unit having a negative focal length, an aperture stop, and a positive lens. A third group having a focal length of and a fourth group having a positive focal length. The second, third, and fourth groups are movable,
During zooming from the short focal end to the long focal end, the second unit moves monotonously from the object side to the image side, and the third unit moves first from the image side to the object side, and has a longer focal length than the intermediate focal length. In the area on the side, it moves closest to the object side, and then moves to the image side.
A zoom lens that is performed by moving a group, comprising a macro mode in which a second group and a third group are arranged in a different positional relationship from that during zooming, and focusing is performed at a shorter distance than a normal shooting area. Focusing is performed by moving the fourth group.

The zoom lens having a macro mode according to claim 3 is the zoom lens having the macro mode according to claim 1 or 2, wherein the position of the third lens unit in the macro mode is the third lens at the long focal length end. It is characterized by substantially matching the position of the group.

According to a fourth aspect of the present invention, there is provided a zoom lens having a macro mode according to any one of the first to third aspects, wherein the position of the second group in the macro mode is at the short focal length end. It is characterized by being closer to the image plane than the position of the second lens unit.

According to a fifth aspect of the present invention, there is provided a zoom lens having a macro mode according to any one of the first to fourth aspects, wherein the first unit is always fixed to an image plane. It is characterized by being.

A zoom lens having a macro mode according to claim 6 is the zoom lens having a macro mode according to any one of claims 1 to 5, wherein the aperture stop is always fixed to the image plane. It is characterized by the following.

According to a seventh aspect of the present invention, there is provided a zoom lens having a macro mode according to any one of the first to sixth aspects, wherein the third lens unit and the fourth lens unit when focused to infinity are used. The distance from the group is the shortest at the short focal length end.

The zoom lens having the macro mode according to claim 8 is the zoom lens having the macro mode according to any one of claims 1 to 7, wherein

[0015]

F _12T / f ₁ <−1.0 where f ₁ : focal length of the first lens unit f _12T : composite focal length of the first lens unit and the second lens unit at the long focal length end

It is characterized by satisfying the following.

Normally, in this type of zoom lens, focusing in the normal photographing area is performed by moving the fourth lens group. However, in order to achieve a reduction in the size of the lens system, particularly, a reduction in the overall length, the third lens group must be moved. Since it is necessary to reduce the distance from the fourth lens unit, the movement amount of the fourth lens unit is naturally limited, and it is difficult to extremely shorten the shortest photographing distance, for example, focus to the front end of the lens. Therefore, in the zoom lens having the macro mode according to the first aspect, by arranging the second group and the third group in a different positional relationship from that during zooming, the macro mode capable of focusing at a shorter distance than the normal shooting area. Is composed.

In this case, in the macro mode, it is necessary to perform focusing from the shortest photographing distance in the normal photographing area to a short distance (the shortest photographing distance in the macro mode). It is important that the fourth group is the same as the group that moves for focusing in the shooting area. Both the focusing in the normal shooting area and the focusing in the macro mode are performed by moving the fourth group, so that only one group driven by the focus signal from the distance measuring unit or the like is required, and The mechanism can be simplified.

Also, in the zoom lens according to the second aspect, similarly to the zoom lens according to the first aspect, the second lens is provided.
By arranging the third group and the third group in a different positional relationship from that during zooming, a macro mode capable of focusing at a shorter distance than the normal shooting area is configured, and both focusing in the normal shooting area and focusing in the macro mode are performed in the second mode. Since the movement is performed by the movement of the four groups, the same operation is achieved.

In zooming from the short focus end to the long focus end, in the case of the first aspect, the third lens unit moves monotonously from the image side to the object side. , The third group first moves from the image side to the object side, and approaches the object side most in the region on the long focal length side from the intermediate focal length,
Thereafter, the lens unit moves to the image side, so that the fourth unit at the time of focusing to infinity can be fixed at a fixed position. For example, adjustment of the second unit and the third unit when assembling a zoom lens Becomes easier.

When a zoom lens having a macro mode as described in claim 1 or 2 is constructed, the position of the third lens unit in the macro mode is the third lens position at the long focal length end.
It is desirable that the position substantially coincides with the position of the group (claim 3).

Normally, when focusing is performed by moving the fourth lens unit, the height of the off-axis ray passing through the third lens unit increases as the focusing is performed at a shorter distance. Easy to invite. On the other hand, if a sufficient amount of peripheral light is to be ensured, the size of the third lens unit will be increased. The third lens unit is closest to the aperture stop at the long focal length end. At this time, the vignetting of the peripheral light beam by the third lens unit is minimized. For this reason, by setting the position of the third unit in the macro mode near the aperture stop similarly to the long focal end, even when focusing is performed at a short distance by moving the fourth unit, vignetting of the peripheral light beam by the third unit is reduced. Minimizing the amount of peripheral light and increasing the size of the third lens group can be prevented.

When a zoom lens having a macro mode is constructed as in claims 1 to 3, the position of the second unit in the macro mode is closer to the image plane than the position of the second unit at the short focal length end. Is desirable (claim 4).

In the zoom lens having the above-described configuration, a large negative distortion is likely to occur at the short focal length end. When focusing is performed by moving the fourth lens unit, the closer the focusing is to a short distance, the better. Distortion increases. The reason that large negative distortion is likely to occur at the short focal length end is that the second group is closest to the first group,
This is because a strong negative power is generated far from the object side of the aperture stop. For this reason, even in the macro mode, when the second group is close to the first group, similarly large negative distortion is likely to occur. Therefore, by displacing the position of the second unit in the macro mode to some extent from the first unit, it is possible to suppress the negative distortion to a small value.

Thus, the second group in the macro mode,
By arranging the third unit as described above, the focal length in the macro mode is longer than the short focal length end of zooming and shorter than the long focal length end. In this state, by setting the focusing range in the macro mode from the shortest photographing distance in the normal photographing area to a shorter distance, there is no discontinuity in the achievable photographing magnification.

In order to realize a zoom lens having a macro mode according to the first to fourth aspects with a simpler mechanism, it is desirable that the first unit is always fixed to the image plane ( Claim 5).

Although the fact that the first lens unit is fixed during zooming and focusing is not particularly new, it is not necessary to move the first lens unit even when switching from the normal photographing area to the macro mode. In particular, fixing of the first group is desired. For this reason, since the largest and heaviest first group is always fixed to the image plane, it is not necessary to increase the number of actuators used for moving the group or increase the torque of the actuators. This is advantageous for power saving.

Further, in order to realize a zoom lens having a macro mode as described in the first to fifth aspects with a simpler mechanism, it is desirable that the aperture stop is always fixed to the image plane. (Claim 6).

In many cases, a shutter is provided at the position of the aperture stop, and the movement of the shutter undesirably complicates the mechanism. Further, the shutter generates vibration when driven, but if the shutter is moved, the vibration is likely to be transmitted to other parts of the lens unit, which may cause image blur. Therefore, the aperture stop is always fixed to the image plane, so that the mechanism is simplified and the occurrence of image blur due to the vibration of the shutter is suppressed.

Further, in order to further reduce the size of the zoom lens having the macro mode as described in claims 1 to 6,
It is desirable that the distance between the third lens unit and the fourth lens unit upon focusing to infinity be the shortest at the short focal length end.

In order to reduce the size of the lens system in a zoom lens having a macro mode, the third lens unit and the fourth lens unit must be used.
As described above, it is desirable that the distance from the group is small and the amount of movement of the fourth group for focusing is limited. In particular, when the distance between the third lens unit and the fourth lens unit when focusing to infinity is the shortest at the short focal length end, the effect of reducing the size of the lens system, particularly shortening the overall length, is great. When focusing to the same distance is considered, the shorter the focal length, the smaller the amount of movement of the focusing group (fourth group). Therefore, in terms of the amount of focusing movement, the short focal end is most advantageous for focusing to a short distance. It is. However, if the distance between the third lens unit and the fourth lens unit when focusing to infinity becomes the shortest at the short focal length end, the shortest focusing distance is reduced even at the short focal length end, which should be the most advantageous. Is very difficult.

In the zoom lens having the macro mode according to the first to seventh aspects, the following conditional expression is satisfied.

[0033]

## EQU2 ## f _12T / f ₁ <−1.0

By making the configuration satisfying the above, further downsizing can be achieved (claim 8).

Here, f _12T / f ₁ is the magnification of the second lens unit at the long focal end. In order to reduce the size of the lens system, it is necessary to increase the power of the first lens unit (shorten the focal length). Therefore, the magnification f _12T / f ₁ of the second lens unit at the long focal end is set to be smaller than −1. It is desirable to do. in this case,
At least at the long focal length end, the prior art (Japanese Unexamined Patent Application Publication No.
Japanese Patent No. 62687) cannot perform focusing by the second lens group.
It is necessary to bring the group close to the image plane, and the group interferes with the aperture stop. However, if the macro mode according to claim 8 is used, there is no obstacle.

[0036]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described. (First Embodiment) FIG. 1 is a cross-sectional view showing the configuration of a zoom lens according to a first embodiment of the present invention and the concept of group movement, and FIG. 2 is a sectional view of the zoom lens according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a configuration in a macro mode, FIG. 3 is an aberration curve diagram at a short focal length end and infinity of the zoom lens according to the first embodiment, and FIG. 4 is a zoom curve according to the first embodiment. FIG. 5 is an aberration curve diagram at the intermediate focal length of the lens at infinity, and FIG. 5 is an aberration curve diagram at the long focal end of the zoom lens according to the first embodiment at infinity.
FIG. 7 is an aberration curve diagram at the short focal length end of the zoom lens according to the first embodiment at a shooting distance of 0.3 m, and FIG. 7 is an intermediate focal length and shooting distance of the zoom lens according to the first embodiment at 0.3 m. FIG. 8 is an aberration curve diagram at 3 m, and FIG.
FIG. 9 is an aberration curve diagram at the long focal end of the zoom lens according to the first embodiment at a shooting distance of 0.3 m, and FIG. 9 is an aberration curve diagram at a macro mode of the zoom lens according to the first embodiment at a shooting distance of 0.3 m. FIG. 10 is an aberration curve diagram of the zoom lens according to the first embodiment in the macro mode at a shooting distance of 0.07 m. 3 to 10 show spherical aberration, astigmatism, distortion, and coma, respectively. The broken line in the figure showing the spherical aberration represents the sine condition, the solid line in the figure showing the astigmatism represents sagittal, and the broken line represents the meridional.

As shown in FIGS. 1 and 2, the zoom lens according to the first embodiment includes a first group G11 having a positive focal length and arranged on the optical axis in order from the object side; A parallel plane plate F1 including a second unit G12 having a negative focal length, an aperture stop S1, a third unit G13 having a positive focal length, a fourth unit G14 having a positive focal length, and various filters.
It is composed of

Here, the first group G11 comprises three lenses of first to third lenses, the second group G12 comprises three lenses of fourth to sixth lenses, and the third group G13 Is composed of three lenses, a seventh lens to a ninth lens, and a fourth group G14
Consists of three lenses, a tenth to a twelfth lens. The first group G11 and the aperture stop S1 are always fixed with respect to the image plane.

Then, as shown in the upper part of FIG.
Focusing at the short focal length end is performed by moving the fourth unit G14. Also, as shown in the lower part of FIG.
Focusing at the long focal length end is also performed by moving the fourth lens group G14, as in the case of the short focal length end.

In zooming from the short focal length end to the long focal length end, the second lens unit G12 moves from the object side to the image side as indicated by an arrow between the upper part and the lower part of FIG. The third group G13 monotonously moves from the image side to the object side.

Also, as shown in FIG. 2, in the macro mode in which focusing is performed at a shorter distance than the normal photographing area, the focusing at that time is performed in the same manner as in the case of the short focus end and the long focus end. This is performed by moving G14. Also, the second group G12 in this macro mode
Is the second group G at the short focal length end shown in the upper part of FIG.
It is arranged at a position closer to the image plane than position 12. Similarly, the third group G13 is disposed at a position substantially coincident with the position of the third group G13 at the long focal end shown in the lower part of FIG.

(Second Embodiment) FIG. 11 shows a second embodiment of the present invention.
FIG. 12 is a cross-sectional view showing the configuration of the zoom lens according to the second embodiment and the concept of group movement, FIG. 12 is a cross-sectional view showing the configuration of the zoom lens according to the second embodiment in macro mode, and FIG. FIG. 14 is an aberration curve diagram at the short focal length end, infinity of the zoom lens according to the second embodiment. FIG. 14 shows an intermediate focal length of the zoom lens according to the second embodiment;
15 is an aberration curve diagram at infinity, FIG. 15 is an aberration curve diagram at a long focal end of the zoom lens according to the second embodiment at infinity, and FIG. 16 is a diagram of the zoom lens according to the second embodiment. FIG. 17 is an aberration curve diagram at a short focal length end and a photographing distance of 0.3 m, FIG. 17 is an aberration curve diagram at an intermediate focal length and a photographing distance of 0.3 m of the zoom lens according to the second embodiment, and FIG. FIG. 19 is an aberration curve diagram of the zoom lens according to the second embodiment at the long focal end and a shooting distance of 0.3 m. FIG. FIG. 20 is a diagram illustrating aberration curves of the zoom lens according to the second embodiment in the macro mode at a shooting distance of 0.074 m. 13 to 20 show spherical aberration, astigmatism, distortion, and coma, respectively. The broken line in the figure showing the spherical aberration represents the sine condition, the solid line in the figure showing the astigmatism represents sagittal, and the broken line represents the meridional.

As shown in FIGS. 11 and 12, the zoom lens according to the second embodiment includes a first lens unit G21 having a positive focal length and arranged on the optical axis in order from the object side.
A second group G22 having a negative focal length, and an aperture stop S2.
, A third lens unit G23 having a positive focal length, a fourth lens unit G24 having a positive focal length, and a plane-parallel plate F2 including various filters.

Here, the first group G21 includes three lenses of first to third lenses, the second group G22 includes three lenses of fourth to sixth lenses, and a third group G23. Is composed of three lenses, a seventh lens to a ninth lens, and a fourth unit G24
Consists of two lenses, the tenth to eleventh lenses. The first group G21 and the aperture stop S2 are always fixed with respect to the image plane.

Then, as shown in the upper part of FIG. 11, focusing at the short focal length end is performed by the fourth unit G24.
This is done by moving. Also, as shown in the lower part of FIG. 11, focusing at the long focal length end is performed by moving the fourth lens group G24, as in the case of the short focal length end.

In zooming from the short focal length end to the long focal length end, the second unit G22 moves from the object side to the image side as indicated by the arrow between the upper and lower parts of FIG. The third group G23 moves from the image side to the object side first, unlike the case of the first embodiment, and moves to the most object side in the region on the longer focal length side than the intermediate focal length. It approaches and then moves to the image side.

Also, as shown in FIG. 12, in the macro mode in which focusing is performed at a shorter distance than the normal photographing area, focusing at that time is performed in the same manner as in the case of the short focus end and the long focus end. This is performed by moving G24. Also, the second group G2 in this macro mode
2 is a second lens at the short focal length end shown in the upper part of FIG.
It is arranged at a position closer to the image plane than the position of the group G22. Similarly, the third group G23 is arranged at a position substantially coincident with the position of the third group G23 at the long focal end shown in the lower part of FIG.

[0048]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific numerical data of a zoom lens according to an embodiment of the present invention will be described below. The meanings of the symbols in this embodiment are as follows.

[0049]

[Table 1] ｆ f: Focal length of the whole system F / No . : F-number ω: Half angle of view R: Curvature radius D: Surface spacing N _d : Refractive index ν _d : Abbe number K: Aspherical conical constant A ₄ : Fourth-order aspherical coefficient A ₆ : Sixth-order aspherical surface Coefficient A ₈ : 8th-order aspherical coefficient A ₁₀ : 10th-order aspherical coefficient ─────────────────────────────── ─────

However, the aspherical surface used here is defined by the following equation, where C is the reciprocal of the paraxial radius of curvature and H is the height from the optical axis.

[0051]

(Equation 3)

(First Example) Specific numerical data of the zoom lens according to the first embodiment is as follows.

[0053]

[Table 2]

In the above table, the surface marked with an asterisk (*) indicates that the surface is an aspheric surface, and the conical constant and the aspheric surface coefficient are as follows.

Aspherical surface; sixth surface

[0056]

K = 0.0 A ₄ = 8.68431 × 10 ⁻⁵ A ₆ = −1.444766 × 10 ⁻⁶ A ₈ = 2.09929 × 10 ⁻⁸ A ₁₀ = −1.58449 × 10 ^{− Ten}

Aspherical surface; twelfth surface

[0058]

K = −6.18832 A ₄ = 3.335200 × 10 ⁻⁵ A ₆ = −3.1800 × 10 ⁻⁶ A ₈ = 8.89782 × 10 ⁻⁸ A ₁₀ = −2.24716 × 10 ^-9

Aspheric surface; surface 23

[0060]

K = 0.0 A ₄ = 1.82984 × 10 ⁻⁴ A ₆ = −1.42913 × 10 ⁻⁶ A ₈ = 3.3456 × 10 ⁻⁸ A ₁₀ = −2.999026 × 10 ^{− Ten}

The variable interval in the normal photographing area is
It is as follows.

[0062]

[Table 3]

The variable interval in the macro mode is
It is as follows.

[0064]

[Table 4]

The numerical values of the conditional expressions are as follows.

[0066]

## EQU7 ## f _12T / f ₁ = −1.324

Second Example Specific numerical data of the zoom lens according to the second embodiment is as follows.

[0068]

[Table 5]

In the above table, the surface marked with an asterisk (*) indicates that the surface is an aspheric surface, and the conical constant and the aspheric surface coefficient are as follows.

Aspherical surface; sixth surface

[0071]

K = 0.0 A ₄ = 8.76330 × 10 ⁻⁵ A ₆ = −1.00557 × 10 ⁻⁶ A ₈ = 8.70046 × 10 ⁻⁹ A ₁₀ = −4.665380 × 10 ^{− 11}

Aspherical surface; thirteenth surface

[0073]

K = −4.777319 A ₄ = 1.290 × 10 ⁻⁴ A ₆ = −1.3660 × 10 ⁻⁷ A ₈ = −1.21202 × 10 ⁻⁷ A ₁₀ = 3.23950 × 10 ^-9

Aspherical surface; 23rd surface

[0075]

K = 3.43729 A ₄ = 2.77810 × 10 ⁻⁴ A ₆ = −1.81528 × 10 ⁻⁶ A ₈ = 3.16416 × 10 ⁻⁸ A ₁₀ = −4.87685 × 10 ^{− Ten}

The variable interval in the normal photographing area is
It is as follows.

[0077]

[Table 6]

The variable interval in the macro mode is
It is as follows.

[0079]

[Table 7]

The numerical values of the conditional expressions are as follows.

[0081]

F _12T / f ₁ = −1.073

As described above, the aberrations in the first and second embodiments are sufficiently corrected in both the normal photographing area and the macro mode, and can correspond to a light receiving element exceeding 3,000,000 pixels. It has become. That is, it is clear from the first and second examples that very good image performance can be secured by configuring a zoom lens having a macro mode as in the first and second embodiments. .

Further, in the first embodiment, at a photographing distance of 0.07 m (from the image plane) in the macro mode, about 0.3 mm is obtained.
A sufficient photographing magnification of 3 times can be obtained. Also, the second
In the embodiment of the present invention, a sufficient photographing magnification of about 0.3 times can be obtained at a photographing distance of 0.074 m (from the image plane) in the macro mode.

[0084]

As described in detail above, according to the zoom lens having the macro mode of the present invention, the following effects can be obtained. That is, according to the first aspect of the present invention, by arranging the second group and the third group in a different positional relationship from that during zooming, the second group and the third group have a macro mode in which focusing can be performed at a shorter distance than the normal shooting area. Since it is possible to provide a zoom lens that is small and has a macro mode with a simple mechanism, focusing can be performed at a short distance and the maximum photographing magnification is high. A digital camera can be realized without increasing costs.

According to the second aspect of the present invention, the second
By arranging the third lens group and the third lens group in a different positional relationship from that during zooming, the same effect as that of the first aspect can be obtained, and the third lens group can be zoomed from the short focal length end to the long focal length end. The first group moves from the image side to the object side, approaches the object side most in a region longer than the intermediate focal length, and then moves to the image side. The group can be fixed at a fixed position, and for example, adjustment of the second group and the third group at the time of assembling the zoom lens can be easily performed.

According to the third aspect of the present invention, the position of the third lens unit in the macro mode is changed to the third position at the long focal length end.
By making the position substantially coincide with the position of the group, it is possible to provide a zoom lens having a macro mode capable of securing a sufficient peripheral light amount even in the macro mode.

According to the fourth aspect of the present invention, the position of the second lens unit in the macro mode is changed to the second position at the short focal length end.
By bringing the zoom lens closer to the image plane than the position of the group, it is possible to provide a zoom lens having a macro mode with small distortion even in the macro mode, thereby realizing a digital camera having sufficient image performance even in the macro mode. be able to.

According to the fifth aspect of the present invention, the first
Since the group is always fixed with respect to the image plane, it is possible to provide a zoom lens having a macro mode that can be realized with a simpler mechanism. Thus, a power-saving digital camera can be realized.

Further, according to the invention of claim 6, it is possible to provide a zoom lens having a macro mode which can be realized by a simpler mechanism since the aperture stop is always fixed to the image plane. Therefore, it is possible to realize a low-cost and power-saving digital camera while enabling focusing to a short distance.

According to the seventh aspect of the present invention, the distance between the third lens unit and the fourth lens unit when focusing to infinity is made the shortest at the short focal length end, so that a macro suitable for further miniaturization. Since a zoom lens having a mode can be provided, a more compact digital camera can be realized while focusing on a short distance is possible.

According to the eighth aspect of the present invention,

[0092]

## _EQU12 ## f _12T / f ₁ <−1.0

By satisfying the above condition, it is possible to provide a zoom lens having a macro mode suitable for further miniaturization, so that a more compact digital camera can be provided while focusing on a short distance is possible. Can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a zoom lens according to a first embodiment of the present invention and a concept of group movement.

FIG. 2 is a cross-sectional view illustrating a configuration in a macro mode of the zoom lens according to the first embodiment of the present invention.

FIG. 3 is an aberration curve diagram at a short focal length end and at infinity of the zoom lens according to the first embodiment of the present invention.

FIG. 4 is an aberration curve diagram at an intermediate focal length and infinity of the zoom lens according to the first embodiment of the present invention.

FIG. 5 is an aberration curve diagram at a long focal end of the zoom lens at infinity according to the first embodiment of the present invention.

FIG. 6 is an aberration curve diagram at a short focal length end and a shooting distance of 0.3 m of the zoom lens according to the first embodiment of the present invention.

FIG. 7 is an aberration curve diagram at an intermediate focal length and a shooting distance of 0.3 m of the zoom lens according to the first embodiment of the present invention.

FIG. 8 is an aberration curve diagram at a long focal length end and a shooting distance of 0.3 m according to the first embodiment of the present invention.

FIG. 9 is an aberration curve diagram at a shooting distance of 0.3 m in a macro mode of the zoom lens according to the first embodiment of the present invention.

FIG. 10 is an aberration curve diagram of the zoom lens according to the first embodiment of the present invention in a macro mode at a shooting distance of 0.07 m.

FIG. 11 is a cross-sectional view illustrating a configuration of a zoom lens and a concept of group movement according to a second embodiment of the present invention.

FIG. 12 is a cross-sectional view illustrating a configuration of a zoom lens according to a second embodiment of the present invention in a macro mode.

FIG. 13 is an aberration curve diagram at a short focal length end and at infinity of a zoom lens according to a second embodiment of the present invention.

FIG. 14 is an aberration curve diagram at an intermediate focal length and infinity of a zoom lens according to a second embodiment of the present invention.

FIG. 15 is an aberration curve diagram at a long focal end, infinity, of a zoom lens according to a second embodiment of the present invention.

FIG. 16 is an aberration curve diagram at a short focal length end and a shooting distance of 0.3 m of the zoom lens according to the second embodiment of the present invention.

FIG. 17 is an aberration curve diagram at an intermediate focal length and a shooting distance of 0.3 m of the zoom lens according to the second embodiment of the present invention.

FIG. 18 is an aberration curve diagram at a long focal length end and a shooting distance of 0.3 m according to a second embodiment of the present invention.

FIG. 19 is an aberration curve diagram at a shooting distance of 0.3 m in the macro mode of the zoom lens according to the second embodiment of the present invention.

FIG. 20 is an aberration curve diagram at a shooting distance of 0.074 m in a macro mode of the zoom lens according to the second embodiment of the present invention.

[Explanation of symbols]

 G11 First group G12 Second group G13 Third group G14 Fourth group S1 Aperture stop F1 Parallel plane plate G21 First group G22 Second group G23 Third group G24 Fourth group S2 Aperture stop F2 Parallel plane plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H044 EF04 GA07 GA24 2H087 KA02 KA03 MA01 MA15 PA08 PA10 PA19 PA20 PB11 PB12 QA02 QA07 QA17 QA21 QA25 QA34 QA42 QA45 QA46 RA05 RA12 RA13 RA32 RA42 SA23 SA63 SA32 SA32 SA32 SA32 SA32 SA32 SA32 SA32 SA32 SA32 SA32 SA32 SA32 SA32 SA32 SA32 SA32 SA32 SA72 SA65 SB14 SB24 SB33 SB34

Claims (8)

[Claims] 1. A first lens unit having a positive focal length, a second lens unit having a negative focal length, an aperture stop, a third lens unit having a positive focal length, and a positive focal point in order from the object side. A fourth lens group having a distance, wherein the second lens group, the third lens group, and the fourth lens group are movable, and when zooming from the short focal length end to the long focal length end,
The second group moves monotonously from the object side to the image side, the third group moves monotonously from the image side to the object side, and also performs focusing in a normal shooting area by moving the fourth group. A lens, having a macro mode in which the second group and the third group are arranged in a different positional relationship from that during zooming, and focusing is performed at a shorter distance than a normal shooting area; A zoom lens having a macro mode, wherein the zoom lens is moved by moving the fourth group. 2. A first lens unit having a positive focal length, a second lens unit having a negative focal length, an aperture stop, a third lens unit having a positive focal length, and a positive focal point in order from the object side. A fourth lens group having a distance, wherein the second lens group, the third lens group, and the fourth lens group are movable, and when zooming from the short focal length end to the long focal length end,
The second group moves monotonously from the object side to the image side, and the third group moves first from the image side to the object side, and comes closest to the object side in a region longer on the focal length side than the intermediate focal length. A zoom lens that moves to the image side and performs focusing in a normal shooting area by moving the fourth group, wherein the second group and the third group are arranged in a different positional relationship from that during zooming. A zoom lens having a macro mode, wherein the zoom lens has a macro mode in which focusing is performed at a shorter distance than a normal shooting area, and focusing in the macro mode is performed by moving the fourth group. 3. The zoom lens having a macro mode according to claim 1, wherein a position of the third group in the macro mode substantially coincides with a position of the third group at a long focal end. Zoom lens with macro mode. 4. The zoom lens having a macro mode according to claim 1, wherein the position of the second group in the macro mode is closer to the image plane than the position of the second group at the short focal length end. A zoom lens having a macro mode. 5. The zoom lens having a macro mode according to claim 1, wherein the first group is always fixed to an image plane. lens. 6. A zoom lens having a macro mode according to claim 1, wherein said aperture stop is always fixed to an image plane. . 7. The zoom lens having a macro mode according to claim 1, wherein the third lens unit and the fourth lens unit when focusing to infinity are set.
A zoom lens having a macro mode, wherein an interval between the groups is shortest at a short focal length end. 8. The zoom lens having a macro mode according to claim 1, wherein the following conditional expression is satisfied. f _12T / f ₁ <−1.0 where f ₁ represents the focal length of the first lens unit, and f _12T represents the combined focal length of the first lens unit and the second lens unit at the long focal end.