JPH09211319A - Macro lens - Google Patents

Abstract

(57) Abstract: To obtain a macro lens capable of obtaining good optical performance over a wide range from an object at infinity to a near object. A first-a group having a positive refractive power in order from the object side,
It has four lens groups of a positive refractive power 1b group, a negative refractive power second group, a positive refractive power third group, and a fourth lens group, and the 1b group has a concave surface on the image side. A negative meniscus-shaped first 1b1 lens and a positive first 1b2 lens, which are used for focusing from an infinite object to a short-distance object by moving at least the second group toward the image plane side. The combined focal length f1 of the group 1b and the focal length f1b of the group 1b, and the refracting power φ of the lens surface on the image side of the lens 1b1 are set appropriately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a macro lens suitable for a camera having an autofocus function, such as a photographic camera, a video camera, and an electronic still camera. A high-performance medium-telephoto macro lens with an angle of view of about 14 degrees and an F-number of about 3.5, which has excellent aberration correction when focusing on a wide range of objects up to a shooting magnification of 1.0x). Is.

[0002]

2. Description of the Related Art Conventionally, photographic cameras and video cameras,
There is a so-called macro lens or micro lens (hereinafter referred to as "macro lens") as a photographing lens mainly for photographing a short-distance object in an electronic still camera or the like.

Of these, many macro lenses for 35 mm single-lens reflex cameras are constructed so as to be capable of photographing in a wide range of object distances from an infinite object to a short-distance object having a photographing magnification of about 1x or 0.5x. .

The macro lens is designed so as to obtain a high optical performance especially for a short-distance object as compared with other photographing lenses such as a general standard lens and a telephoto lens. In addition, the macro lens is often used not only for a short-distance object but also for a wide range of objects from a short-distance object to an infinite object.

Generally, when trying to expand the object distance range (shooting magnification range) in a macro lens, aberration fluctuations associated with focusing increase. For example, when the photographing magnification becomes high, the spherical aberration is insufficiently corrected, and a lot of outward coma occurs.

On the other hand, JP-A-55-140810
In the publication, the first lens group is composed of three lens groups of positive, negative, and positive refractive powers in order from the object side, that is, a first lens group, a second lens group, and a third lens group. A macro lens has been proposed in which the second group is moved toward the object side toward the image plane side, and thereby the aberration variation due to focusing is corrected well.

Further, in Japanese Patent Application No. 4-124480, a 1a group having a positive refracting power, a 1b group having a positive refracting power, in order from the object side,
It is composed of a second group of negative refracting power and a third group of positive refracting power, and when focusing from an object at infinity to a short-distance object, the second group is moved to the image side and the 1a group is at the object side. There has been proposed a macro lens having a configuration in which it is moved so as to draw a convex arc.

[0008]

Since the macro lens is capable of photographing in a wide range of object distances, the focusing lens has a large amount of extension (movement amount) as compared with a general photographing lens. Further, as the focal length of the entire system becomes longer, the amount of extension of the focusing lens tends to increase in proportion thereto and the lens weight of the focusing lens group tends to increase.

Taking a taking lens (macro lens) of the entire extension type as the focus type as an example, the same F
When focusing on an object with the same shooting magnification with a shooting lens with a focal length of 100 mm and a focal length of 200 mm, a shooting lens with a focal length of 200 mm has a focal length of 10 mm.
The extension amount is twice as much as that of a 0 mm taking lens, and the lens weight is also considerably increased.

In recent years, in an autofocus type camera which has been actively developed, such an increase in the focus extension amount and the lens weight has become a very serious problem in realizing high speed autofocus.

Further, when the photographing magnification range of the macro lens is expanded, particularly when the photographing magnification is expanded to a high magnification, the variation of aberration increases with the change of the photographing magnification, and it becomes very difficult to satisfactorily correct this.

As described above, in the macro lens, it is a major problem to correct various aberrations while reducing the lens weight of the focusing lens group and reducing the lens extension amount.

According to the present invention, mainly by appropriately setting the lens configuration and the allocation of the refractive power, a wide range of object distances from an object at infinity to a near object, especially a photographing magnification of around 1.0 times. For the purpose of providing a medium-telephoto macro lens having a high optical performance of about F number 3.5, which is particularly suitable for an autofocus camera, in which aberration variation during focusing is favorably corrected. To do.

[0014]

A macro lens according to the present invention comprises, in order from the object side, a 1a group having a positive refracting power, a 1b group having a positive refracting power, a second group having a negative refracting power, and a positive refracting power. Third of power
Group, and four lens groups of the fourth group, the 1b group has a meniscus negative 1b1 lens having a concave surface facing the image side and a positive 1b2 lens, and At the time of focusing on a short-distance object, at least the second group is moved to the image plane side, the combined focal length of the first group a and the first group b is f1, the focal length of the first group b is f1b, and the first group is f1b.
When the refractive power of the lens surface of the b1 lens on the image plane side is φ, 1.4 <| φ | · f1 <2.6 (1) 2 <f1b / f1 <15 (2) Characterized by satisfaction.

[0015]

1 to 11 are lens cross-sectional views of Numerical Embodiments 1 to 11 of the present invention, respectively. 12 to 55
[Fig. 3] is an aberration diagram of each of Numerical Examples 1 to 11 of the present invention.
In the aberration diagrams, an object at infinity and photographing magnifications 0.1x, 0.5x, 1.0x are shown for each numerical example.

In the sectional view of the lens, L1a is a first lens group having a positive refractive power, L1b is a first lens group having a positive refractive power, L2 is a second lens group having a negative refractive power, and L3 is a third lens group having a positive refractive power. Group, L4
Is a fourth group of positive or negative refractive power, SP is a diaphragm,
It is arranged between the group L2 and the third group L3.

In each of the embodiments, the 1b-th group is constructed to have a meniscus-shaped negative 1b1 lens with a concave surface facing the image side and a positive 1b2 lens. When focusing from an object at infinity to a near object, the second lens unit L2 is moved to the image plane side as indicated by an arrow. Third
The group L3 is moved to the object side as necessary, but may be fixed.

As described above, in the present embodiment, the lens configuration is specified, and the refractive power of the lens surface on the image side of the first group b, the first group, and the first b1 lens is expressed by the conditional expression (1),
The setting is made as shown in (2), thereby reducing the fluctuation of aberration due to the change of the photographing magnification, and making it possible to perform good aberration correction on a wide range of objects from an object at infinity to an object at a short distance. In particular, good aberration correction is possible for a wide range of objects from an object at infinity to an object at a short distance with a magnification of 1.0.

Next, the features of aberration correction of the macro lens of the present invention will be described. The macro lens according to the present invention focuses on a wide range of object distances, and the variation of various aberrations associated with focusing at this time will be described using the paraxial refractive power arrangement of FIG.

FIG. 56 shows the first lens unit L1a having positive refractive power among the four lens units constituting the macro lens of the present invention.
The first lens unit L1b having a positive refractive power and the second lens unit L2 having a negative refractive power
FIG. 3 is an explanatory diagram showing an optical path state when light rays pass through this lens system by extracting the three lens groups.

FIG. 56 (A) shows a state in which an object at infinity is focused, and FIG. 56 (B) shows a state in which the second lens unit L2 is moved to the image plane side as shown by an arrow to focus on a near object. Shows. As described above, since the macro lens has a wide object distance photographing range, various aberrations are likely to occur during focusing. In particular, the basic spherical aberration tends to be significantly undercorrected. This will be described with reference to the on-axis light flux passage diagram of FIG.

First, in the in-focus state of an object at infinity shown in FIG. 56A, it is assumed that the spherical aberration as a combined system from the first lens unit L1a lens unit to the second lens unit L2 is in a good correction state. The canceling state inside the first group L1a and the first group L1a
Negative spherical aberration is generated in the positive refractive power compound lens system of the b-group L1b, and it is corrected in a well-balanced manner by canceling it out by the positive spherical aberration generated in the second lens-group of negative refractive power.

However, in the in-focus state for the short-distance object shown in FIG. 56B, the height of incidence of the axial light flux into the second lens unit becomes low because the second lens unit L2 moves to the image plane side. Therefore,
The amount of positive spherical aberration generated from the second lens unit L2 decreases.

As a result, the first group L1a to the second group L2
The spherical aberration tends to be significantly undercorrected in the synthetic system. Therefore, in order to prevent the spherical aberration from being significantly undercorrected during focusing in the macro lens having such a lens configuration, as the subject distance becomes closer, the spherical aberration of the second group becomes closer to the negative direction. In order to cancel the displacement, it is necessary to configure the combined system of the first-a group and the first-b group so that the spherical aberration is displaced in the positive direction.

Therefore, in the present invention, the meniscus-shaped negative lens (the first lens group 1b having the concave surface facing the image side of the first lens group in order from the object side).
One lens) and a positive lens (first b2 lens) are included, whereby spherical aberration is largely displaced in the positive direction.

That is, the incident height of the axial ray on the 1b-th lens group is higher than that in the infinity in-focus state shown in FIG.
Paying attention to the fact that the short-distance focused state of (B) is higher,
By utilizing this, the spherical aberration is largely displaced in the positive direction mainly on the image-side lens surface of the meniscus-shaped negative lens arranged therein. The subsequent positive lens is used especially for maintaining the first-b group as a whole with a positive refracting power. When this positive lens is removed, the contribution of the positive refracting power of the 1a group increases, and it becomes difficult to correct various aberrations in the 1a group at the same time, and at the same time, the negative surface of the meniscus-shaped negative lens on the image side. The curvature of the lens surface becomes loose, and the effect of displacement of spherical aberration in the positive direction is weakened. Further, when the meniscus-shaped negative lens and the positive lens are cemented, the effect of displacing the spherical aberration in the positive direction is weakened, so that they are separated.

The macro lens of the present invention, by adopting the lens configuration as described above, favorably corrects aberration fluctuations during focusing, particularly spherical aberration fluctuations.

Next, the technical meaning of the above conditional expression will be described. Conditional expression (1) relates to the refracting power of the image-side lens surface of the negative meniscus 1b1 lens with the concave surface facing the image surface side in the 1b-th group, and mainly relates to the entire system when focusing on a short-distance object. This is a condition for suppressing the fluctuation of various aberrations, especially the displacement of the spherical aberration in the negative direction, effectively displacing it in the positive direction on this lens surface to suppress the fluctuation of the aberration of the entire system.

If the diverging action of the lens surface is increased beyond the upper limit of conditional expression (1), spherical aberration is greatly displaced in the positive direction during focusing on a near object, and focusing on a near object is achieved. It is not good because it is overcorrected in the state. Further, when the divergence action of the lens surface becomes weaker than the lower limit of conditional expression (1), the amount of displacement of the spherical aberration in the positive direction becomes small at the time of focusing on an object at a short distance. In the in-focus state, the correction is insufficient, which is not good.

In the present invention, the conditional expression (1) is more preferably 1.8 <| φ | · f1 <2.1 (φ <0) (1a).

Next, the conditional expression (2) relates to the focal length in the 1b-th group, and in the combined system of the 1a-th group and the 1b-th group (first group), the refractive power sharing with the 1a-th group is made appropriate, This is a condition for satisfactorily suppressing fluctuations in various aberrations during focusing.
When the positive refractive power of the 1b-th group is weakened beyond the upper limit of the conditional expression (2), as a result, the share of the positive refractive power of the 1a-th group increases, and spherical aberration and coma in the 1a-th group increase. However, it becomes difficult to correct various aberrations such as astigmatism and field curvature. Especially when focusing on a short-distance object, the fluctuation of the spherical aberration generated in the 1a group is largely displaced in the negative direction by the action of the positive refractive power essentially possessed by the 1a group, and is removed by the subsequent 1b group. It's not good because I can't run out.

If the distribution of the positive refractive power of the 1b-th group is weakened below the lower limit of the conditional expression (2), aberrations in the 1a-th group will be easily corrected, but various aberrations will occur in the 1b-th group. Is unbalanced, and the amount of displacement of spherical aberration in the positive direction during focusing is small in the entire 1b-th group, and correction is insufficient in the in-focus state with a short-distance object, which is not preferable.

According to the present invention, in the lens structure as described above, the refractive power of each lens group is set as in conditional expressions (1) and (2). Aberration variation is reduced for a wide range of objects up to a distance object, and good optical performance is obtained.

In the present invention, it is preferable to satisfy at least one of the following conditions in order to further reduce the aberration variation during focusing and obtain good optical performance over the entire object distance.

First, the focal length of the first group a is preferably (A1) 1.05 <f1a / f1 <1.74 (3) when the focal length of the first group a is f1a. . More preferably, 1.10 <f1a / f1 <1.45 (3a).

(A2) In the first group a, a positive lens whose lens surfaces are convex in order from the object side, a meniscus negative lens whose concave surface faces the object side, and a meniscus positive lens whose convex surface faces the object side. With the configuration having, it is possible to favorably correct variations in various aberrations during focusing, particularly variations in high-order flare of spherical aberration of color.

(A3) The first-a group includes a positive lens in order from the object side, a positive lens having convex lens surfaces on both sides, a meniscus negative lens having a concave surface facing the object side, and a meniscus shape having a convex surface facing the object side. With a positive lens of
This is preferable because it is possible to satisfactorily correct variations in various aberrations including spherical aberration.

(A4) In addition to the lens configuration described above, the first-a group includes, in order from the object side, a negative meniscus lens having a convex surface facing the object side, a positive lens, and a meniscus shape having a convex surface facing the object side. Even if the configuration has a positive lens, the variation of various aberrations can be corrected relatively favorably.

It is also possible to employ so-called floating in which the second lens group is moved during focusing and the other lens groups are moved at different speeds with respect to the second lens group.

That is, (A5) it is preferable to move the third lens unit when focusing from an object at infinity to a near object. In particular, it is preferable to move the third group to the object side.

(A6) It is preferable to move the fourth lens unit when focusing from an object at infinity to a near object. In particular, it is preferable that the fourth lens unit has a positive refractive power and is moved with a convex locus on the image plane side when focusing from an object at infinity to a near object.

(A7) It is preferable to move the first group b when focusing from an object at infinity to a near object.
It is particularly preferable to move the 1b-th group toward the image plane side.

In the present invention, the floating effect can be obtained by moving any of these lens groups, and the fluctuation of the image plane at the intermediate photographing distance can be corrected more favorably.

Especially when focusing on (A5),
When the third lens group is moved to the object side in the opposite direction to the second lens group, (A8) By setting the lens weight and the movement amount to be substantially equal to each other, the lens weights are canceled out by the upward photographing and the downward photographing, and stable. It is preferable because the lens driving speed can be obtained.

(A9) The second lens group has a negative lens having a concave surface facing the image side in order from the object side, and a cemented lens in which a negative lens L2n having a concave lens surface and a positive lens are cemented together. Is good.

Of these, a negative lens L2, both lens surfaces of which are concave
When the refractive index and Abbe number of the material of n are N2n and ν2n, respectively

[0047]

[Equation 1] Good to be. According to this, it is possible to excellently correct the residual chromatic aberration, especially the axial chromatic aberration of the combined system of the 1a-th group and the 1-b-th group.

(A10) When the focal length of the second lens unit is f2 and the focal length of the entire system when focused on an object at infinity of the entire system is f: 0.15 <| f2 | / f <0. 45 (f2 <0) (5) is good.

If the upper limit of conditional expression (5) is exceeded and the negative refracting power of the second lens unit weakens, it becomes easy to correct aberrations, but this is not preferable because the amount of movement of the second lens unit during focusing increases. On the contrary, when the negative refracting power is increased beyond the lower limit, various aberrations generated in the second lens group become large, and at the same time, the first lens group and the first lens group
The positive refracting power of the combined system of the b group is also strengthened, various aberrations generated are increased, and various aberrations of the entire lens system are deteriorated, which is not good.

(A11) The third lens group preferably has a positive lens having a convex surface directed toward the object side and a cemented lens having a positive lens L3p having a convex surface directed toward the object side and a negative lens cemented together. Especially when the refractive index and Abbe number of the material of the positive lens L3p of the cemented lens are N3p and ν3p

[0051]

[Equation 2] Good to be. This is preferable because chromatic aberration, particularly axial chromatic aberration, can be corrected well.

(A12) It is preferable that the fourth lens unit has a meniscus negative lens having a convex surface directed toward the image side and a positive lens having a convex surface directed toward the object side. Alternatively, the fourth
It is preferable that the group includes a positive lens, a meniscus negative lens having a convex surface directed toward the image side, and a positive lens having a convex surface directed toward the object side. This is effective for correcting off-axis aberrations, especially coma and astigmatism.

(A13) The diaphragm may be integral with the second group or integral with the third group, but fixedly arranged between the second group and the third group because a relatively simple mechanism can be constructed. .

Next, numerical examples of the present invention will be shown. In the numerical examples, ri is the radius of curvature of the i-th lens surface in order from the object side, di is the i-th lens thickness and air spacing in order from the object side, and ni and νi are the i-th lens in order from the object side. Are the refractive index and Abbe number of the glass. In addition, the relationship between each conditional expression described above and various numerical values in the numerical examples is shown in [Table-
1].

The aspherical shape has an X axis in the optical axis direction, an H axis in the direction perpendicular to the optical axis, a light traveling direction is positive, R is a paraxial radius of curvature, and A, B, C, D, and E are aspherical shapes, respectively. When using spherical coefficient

[0056]

(Equation 3) It is represented by the following expression.

[0057]

[Outside 1]

[0058]

[Outside 2]

[0059]

[Outside 3]

[0060]

[Outside 4]

[0061]

[Outside 5]

[0062]

[Outside 6]

[0063]

[Outside 7]

[0064]

[Outside 8]

[0065]

[Outside 9]

[0066]

[Outside 10]

[0067]

[Outside 11]

[0068]

[Table 1]

[0069]

As described above, according to the present invention, by appropriately setting the configuration of the entire lens system, in particular, the configuration of the focusing lens group, infinity objects to short-distance objects, in particular, photographing magnification Satisfactorily corrects aberration fluctuations when focusing on a wide range of object distances up to about 1.0 times, especially with high optical performance of F number about 3.5, which is suitable for autofocus cameras. It is possible to achieve a medium-telephoto macro lens that the user has.

[Brief description of drawings]

FIG. 1 is a sectional view of a lens according to a numerical example 1 of the present invention.

FIG. 2 is a sectional view of a lens according to a numerical example 2 of the present invention.

FIG. 3 is a sectional view of a lens according to a numerical example 3 of the present invention.

FIG. 4 is a lens cross-sectional view of Numerical Example 4 of the present invention.

FIG. 5 is a lens cross-sectional view of Numerical Example 5 of the present invention.

FIG. 6 is a lens cross-sectional view of Numerical Example 6 of the present invention.

FIG. 7 is a lens cross-sectional view of Numerical Example 7 of the present invention.

FIG. 8 is a lens cross-sectional view of Numerical Example 8 of the present invention.

FIG. 9 is a lens cross-sectional view of Numerical Example 9 of the present invention.

FIG. 10 is a lens cross-sectional view of Numerical Example 10 of the present invention.

FIG. 11 is a lens cross-sectional view of Numerical Example 11 of the present invention.

FIG. 12 is an aberration diagram of an object at infinity according to Numerical Example 1 of the present invention.

FIG. 13 is an aberration diagram at a shooting magnification of 0.1 × according to Numerical Example 1 of the present invention.

FIG. 14 is an aberration diagram of Numerical Example 1 of the present invention at a photographing magnification of 0.5 ×.

FIG. 15 is an aberration diagram at a shooting magnification of 1.0 × according to Numerical Example 1 of the present invention.

FIG. 16 is an aberration diagram of an object at infinity according to Numerical Example 2 of the present invention.

FIG. 17 is an aberration diagram at a shooting magnification of 0.1 × according to Numerical Example 2 of the present invention.

FIG. 18 is an aberration diagram of Numerical example 2 of the present invention at a photographing magnification of 0.5 ×.

FIG. 19 is an aberration diagram at a shooting magnification of 1.0 × according to Numerical Example 2 of the present invention.

FIG. 20 is an aberration diagram of an object at infinity according to Numerical Example 3 of the present invention.

FIG. 21 is an aberration diagram of Numerical example 3 of the present invention at a photographing magnification of 0.1 ×.

FIG. 22 is an aberration diagram of Numerical example 3 of the present invention at a photographing magnification of 0.5 ×.

FIG. 23 is an aberration diagram of Numerical example 3 of the present invention when the photographing magnification is 1.0 ×.

FIG. 24 is an aberration diagram of an object at infinity according to Numerical Example 4 of the present invention.

FIG. 25 is an aberration diagram of Numerical example 4 of the present invention at a photographing magnification of 0.1 ×.

FIG. 26 is an aberration diagram of Numerical example 4 of the present invention at a photographing magnification of 0.5 ×.

FIG. 27 is an aberration diagram of Numerical example 4 of the present invention at a photographing magnification of 1.0 ×.

FIG. 28 is an aberration diagram of an object at infinity according to Numerical Example 5 of the present invention.

FIG. 29 is an aberration diagram at a shooting magnification of 0.1 × according to Numerical Example 5 of the present invention.

FIG. 30 is an aberration diagram of Numerical example 5 of the present invention at a photographing magnification of 0.5 ×.

FIG. 31 is an aberration diagram of Numerical example 5 of the present invention when the photographing magnification is 1.0 ×.

FIG. 32 is an aberration diagram of an infinite object according to Numerical Example 6 of the present invention.

FIG. 33 is an aberration diagram of Numerical example 6 of the present invention at a photographing magnification of 0.1 ×.

FIG. 34 is an aberration diagram at a shooting magnification of 0.5 × according to Numerical Example 6 of the present invention.

FIG. 35 is an aberration diagram at a shooting magnification of 1.0 × according to Numerical Example 6 of the present invention.

FIG. 36 is an aberration diagram of an object at infinity according to Numerical Example 7 of the present invention.

FIG. 37 is an aberration diagram at a shooting magnification of 0.1 × according to Numerical Example 7 of the present invention.

FIG. 38 is an aberration diagram at a shooting magnification of 0.5 × according to Numerical Example 7 of the present invention.

FIG. 39 is an aberration diagram at a shooting magnification of 1.0 × according to Numerical Example 7 of the present invention.

FIG. 40 is an aberration diagram of an object at infinity according to Numerical Example 8 of the present invention.

FIG. 41 is an aberration diagram of Numerical example 8 of the present invention at a photographing magnification of 0.1 ×.

FIG. 42 is an aberration diagram of Numerical example 8 of the present invention at a photographing magnification of 0.5 ×.

FIG. 43 is an aberration diagram of Numerical Example 8 of the present invention when the photographing magnification is 1.0 ×.

FIG. 44 is an aberration diagram of an object at infinity according to Numerical Example 9 of the present invention.

FIG. 45 is an aberration diagram of Numerical example 9 of the present invention at a photographing magnification of 0.1 ×.

FIG. 46 is an aberration diagram of Numerical Example 9 of the present invention at a photographing magnification of 0.5 ×.

FIG. 47 is an aberration diagram of Numerical example 9 of the present invention at a photographing magnification of 1.0 ×.

FIG. 48 is an aberration diagram of an object at infinity according to Numerical Example 10 of the present invention.

FIG. 49 is a photographing magnification of 0.1 × according to Numerical Example 10 of the present invention.
Aberration diagram when

FIG. 50 is a photographing magnification of 0.5 × according to Numerical Example 10 of the present invention.
Aberration diagram when

FIG. 51 is a photographing magnification of 1.0x according to Numerical Example 10 of the present invention.
Aberration diagram when

52 is an aberration diagram of an infinite object according to Numerical Example 11 of the present invention. FIG.

FIG. 53 is a photographing magnification of 0.1 × according to Numerical Example 11 of the present invention.
Aberration diagram when

FIG. 54 is a photographing magnification of 0.5 × according to Numerical Example 11 of the present invention.
Aberration diagram when

FIG. 55 is a photographing magnification of 1.0x according to Numerical Example 11 of the present invention.
Aberration diagram when

FIG. 56 is an explanatory diagram of the paraxial refractive power arrangement of the macro lens of the present invention.

[Explanation of symbols]

 L1a 1a group L1b 1b group L2 2nd group L3 3rd group L4 4th group d d line g g line S.I. C Sine condition ΔM Meridional image plane ΔS Sagittal image plane

Claims (15)

[Claims] 1. A 1a group having a positive refractive power in order from the object side,
It has four lens groups of a positive refractive power 1b group, a negative refractive power second group, a positive refractive power third group, and a fourth lens group, and the 1b group has a concave surface on the image side. A negative meniscus-shaped first 1b1 lens and a positive first 1b2 lens, at least the second group is moved to the image plane side when focusing from an object at infinity to a near object, and F1 is the combined focal length of the first lens group and the first group b, and f1 is the focal length of the first group b.
b, the refractive power of the lens surface on the image side of the first b1 lens is φ
The macro lens is characterized by satisfying the following condition: 1.4 <| φ | · f1 <2.6 2 <f1b / f1 <15. 2. The macro lens according to claim 1, wherein the condition of 1.05 <f1a / f1 <1.74 is satisfied when the focal length of the first group a is f1a. 3. The first lens group includes a positive lens whose both lens surfaces are convex surfaces, and a negative meniscus lens whose concave surface faces the object side.
The macro lens according to claim 2, further comprising a meniscus-shaped positive lens having a convex surface directed toward the object side. 4. The macro lens according to claim 2, wherein the third lens group is moved during focusing from an object at infinity to a near object. 5. The macro lens according to claim 4, wherein the third lens unit is moved toward the object side when focusing from an object at infinity to a near object. 6. The macro lens according to claim 2, wherein the fourth lens unit is moved during focusing from an object at infinity to a near object. 7. The fourth lens unit has a positive refracting power, and is moved with a convex locus on the image plane side when focusing from an object at infinity to a near object. The macro lens according to claim 6. 8. The macro lens according to claim 2, wherein the first group b is moved when focusing from an object at infinity to a near object. 9. The macro lens according to claim 8, wherein the first group b is moved toward the image plane when focusing from an object at infinity to a near object. 10. The second lens unit has a negative lens whose concave surface faces the image side in this order from the object side, and a negative lens L whose both lens surfaces are concave.
The macro lens according to claim 1, further comprising a cemented lens in which 2n and a positive lens are cemented. 11. The third lens group includes a positive lens having a convex surface directed toward the object side in order from the object side, and a cemented lens in which a positive lens L3p having a convex surface directed toward the object side and a negative lens are cemented together. The macro lens according to claim 1 or 2, wherein. 12. The fourth lens group includes a meniscus negative lens whose concave surface faces the object side in order from the object side, and a positive lens whose convex surface faces the object side. Or 2 macro lenses. 13. The fourth group includes, in order from the object side, a positive lens, a meniscus negative lens having a concave surface facing the object side, and
The macro lens according to claim 1, further comprising a positive lens having a convex surface directed toward the object side. 14. The first lens group comprises, in order from the object side, a positive lens, a positive lens having convex lens surfaces on both sides, a meniscus negative lens having a concave surface facing the object side, and a meniscus lens having a convex surface facing the object side. The macro lens according to claim 3, further comprising a positive lens. 15. The first group aa includes a meniscus negative lens having a convex surface directed toward the object side from the object side, a positive lens, and a meniscus positive lens having a convex surface directed toward the object side. The macro lens according to claim 2, which is characterized in that.