JPH05224123A - Telephoto zoom lens - Google Patents

Abstract

PURPOSE:To provide a telephoto zoom lens for 35mm photograph. CONSTITUTION:Several conditions are satisfied in this zoom lens which is provided with a 1st lens group G1 having positive refracting power, a 2nd lens group G2 having negative refracting power, a 3rd lens group G3 having the negative refracting power, a 4th lens group G4 having the positive refracting power, and a 5th lens group G5 having the negative refracting power in order from an object side; and where the lens groups are moved so that space between the 1st lens group G1 and the 2nd lens group G2 may be increased, space between the 2nd lens group G2 and the 3rd lens group G3 may be changed to be linear or non-linear, and space between the 4th lens group G4 and the 5th lens group G5 may be decreased in the case of variable power from a wide angle end to a telephoto end.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a telephoto zoom lens for 35 mm photographs.

[0002]

2. Description of the Related Art In recent years, with the improvement in performance of zoom lenses,
Various zoom types have been proposed. In the field of these so-called telephoto areas, a 4-group afocal type has been conventionally used, but although the imaging performance is stable, the total length is long and the lens diameter is large, so both the size and weight are large. However, there is a disadvantage that it is disadvantageous in portability and operability.

In recent years, with the advance of lens barrel technology,
A zoom type proposal by moving three or more groups has also been made. However, it has been extremely difficult to achieve both excellent wide-angle, high zoom ratio, small size, and excellent imaging performance.

[0004]

SUMMARY OF THE INVENTION The present invention provides a zoom lens having a relatively short overall lens length and excellent image forming performance, and particularly to a zoom lens in the telephoto range for 35 mm photography.

[0005]

In order to achieve the above-mentioned object, according to the present invention, as shown in FIG. 1, a first lens group G1 having a positive refractive power and a negative refractive power are arranged in order from the object side. A second lens group G2 having a 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. However, during zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3 changes linearly or non-linearly. , A zoom lens in which the lens groups move so that the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the focal length of the first lens group G1 is f1, the focal length of the second lens group G2 is f2, The focal length of the third lens group G3 is f3, the focal length of the fourth lens group G4 is f4, and the fifth lens group is The focal length of the group G5 is f5, the focal length of the entire zoom lens at the wide-angle end is fw, the distance between the second lens group G2 and the third lens group G3 at the wide-angle end is DW2-3, and the entire zoom lens at the telephoto end. When the focal length is fT and the distance between the second lens group G2 and the third lens G3 at the telephoto end is DT2-3, 0.3 ≤ f1 / (fw · ft) ^1/2 ≤ 1.5 (1) 0.3 ≤ f2 / f3 ≤ 5 (2) 0.01 ≤ (DT2-3-DW2-3) / fw ≤ 0.6 (3) The conditions are satisfied.

[0006]

In general, the features of the zoom lens having a multi-lens structure will be described. (In the following description, since at least two movable groups are required to form a normal zoom lens, the term “multi-group” means a zoom lens including three or more groups.) First, the multi-group. In the zoom lens having the configuration, since the number of groups responsible for zooming increases, it is possible to achieve high magnification, and it is easy to equalize the aberration burden of each group, so that excellent imaging performance can be achieved. Further, there have been problems such as complication of the lens barrel structure due to an increase in the number of movable parts, but these are being overcome by the recent advances in lens barrel technology. If these examples are given, various telephoto zoom lenses of 3 or 4 groups have been proposed. However, there are still problems such as difficulty in downsizing and high magnification, and aberration variation during zooming due to zooming.

Secondly, a so-called telephoto type lens will be described. By arranging the positive lens group and the negative lens group at a distance from the object side in order, the total length (the length from the positive lens group to the image plane) can be made shorter than the focal length of the composite system. Such a lens type is called. The telephoto type lens is widely used for a telephoto lens for photography because of its advantage of shortening the overall length.

Thirdly, a conventional telephoto zoom lens such as a 4-group afocal type lens will be described. For example, if the fourth group afocal type (positive / negative positive / positive) is given, the negative second
Since the lens group has a relatively large refracting power and the entire length is invariable, the entire length at the wide-angle end must be long, and there is a limit to compactness. Also, the group responsible for zooming,
Since only the second lens group is used, there is a limit to increase the magnification and correct aberrations.

The present invention has been made on the basis of the technical foundations and background as described in the first to third aspects. That is, the zoom lens of the present invention achieves a shortening of the overall length by using a positive and negative telephoto type lens on the image side, and has a positive, negative, and negative three-group configuration on the object side, from the object side as a whole. In this order, a positive / negative negative positive / negative five-group configuration is adopted. Therefore, the multi-group configuration described above is used, including the telephoto type lens portion on the image side. As a result, it was possible to achieve a compact telephoto zoom lens that makes full use of the characteristics of the multi-group structure, has excellent imaging performance, and can be applied to higher magnification.

In other words, the total length of the zoom lens according to the present invention can be shortened (especially at the wide-angle end) by the positive, negative, negative, positive, and negative multi-group construction, and the number of groups is increased to include the freedom of movement. In addition, since there are many degrees of freedom for aberration correction, excellent imaging performance can be obtained even at high magnification.
In particular, like the present invention, a zoom lens of a type that has a short overall length at the wide-angle end and that extends during zooming to the telephoto end during zooming, compared to a conventional telephoto zoom lens such as a 4-group afocal type, It is possible to reduce the total length at the wide-angle end and the weight of the entire zoom lens.

Further, since the height of the light ray passing through each lens group at the wide-angle end is also small, the occurrence of aberration in each lens group is small, which is advantageous in correcting the aberration on the wide-angle side. Hereinafter, each conditional expression of the present invention will be described in detail. Conditional expression (1) defines an appropriate range for the focal length fW of the zoom lens at the wide-angle end, the focal length fT of the telephoto end, and the focal length f1 of the first lens group G1. Conditional expression (1)
If the value exceeds the upper limit of, the total length at the telephoto end becomes long, which is against the compactness, and it is not preferable because the peripheral light amount at the telephoto end becomes insufficient and the front lens diameter increases. The effect of the present invention can be more exerted by setting the upper limit to 1.0 or less. On the other hand, if the lower limit of conditional expression (1) is exceeded, the focal length f1 of the first lens group G1 becomes too small, and spherical aberration at the telephoto end tends to be undercorrected, resulting in a field curvature during zooming due to zooming. Fluctuations will be enormous. Further, the size of the imaging magnification at the telephoto end by the lens system of the second lens group G2 and thereafter becomes excessively large,
The axial chromatic aberration generated in the lens group G1 is magnified, and good image forming performance cannot be obtained. In order to obtain better imaging performance, it is preferable condition for the lower limit to 0.6 or more (2) is the focal length f2 of the second lens group G ₂
When a condition that defines an appropriate ratio relates to the focal length f3 of the third lens group G _3. If the upper limit of conditional expression (2) is exceeded,
The focal length f3 of the third lens group G3 becomes too short, the variation of coma aberration during zooming due to zooming becomes large, and the distortion at the telephoto end moves largely to the positive side. In addition, positive lower coma occurs at the wide-angle end, and spherical aberration at the telephoto end tends to be overcorrected on the positive side. Therefore, good imaging performance cannot be obtained. Incidentally, if the upper limit is set to 3 or less, better imaging performance can be obtained. If the lower limit of conditional expression (2) is exceeded, the focal length f2 of the second lens group G2 becomes too short, the fluctuation of coma aberration during zooming due to zooming becomes large, and the distortion at the telephoto end largely moves to the negative side. To do. Also, negative lower coma occurs at the wide-angle end, and spherical aberration at the telephoto end tends to be overcorrected. Therefore, good imaging performance cannot be obtained.

The conditional expression (3) defines an appropriate ratio with respect to the difference in the distance between the second lens group G2 and the third lens group G3 of the zoom lens at the wide-angle end and the telephoto end and the focal length fW at the wide-angle end. Is. If the upper limit of conditional expression (3) is exceeded, the total length at the telephoto end becomes too long, which not only causes an increase in the front lens diameter, but also causes the field curvature to move largely to the negative side at both the wide-angle end and the telephoto end. The spherical aberration at the end is uncorrected, which is not preferable. The upper limit is more preferably 0.3 or less. On the contrary, if the lower limit of conditional expression (3) is exceeded,
Since it is not possible to make a large change in the magnification of the third lens group G3, it becomes difficult not only to increase the magnification but to equalize the aberration burden of each group during zooming, but also to reduce the various aberrations during zooming due to zooming. Fluctuation increases. In particular, the curvature of field and coma change greatly, and the field curvature becomes excessive on the negative side at both the wide-angle end and the telephoto end. In addition, positive lower coma occurs at the wide-angle end, causing spherical aberration at the telephoto end. Is overcorrected, which is not preferable.

Further, in order to overcome aberration fluctuations and achieve good image forming performance, focal length states other than the both ends during zooming due to zooming (hereinafter referred to as intermediate focal length state).
The relative positional relationship of each lens group in is important.
Here, the movement locus of the third lens group G3 during zooming due to zooming will be discussed. Third lens group G
When 3 takes a non-linear locus which is convex toward the object side, considering the ray L from the on-axis object point emitted from the second lens group G2 in the intermediate focal length state, the ray L has the following property. First, when the ray L diverges, the spherical aberration can be moved to the negative side, and when the ray L converges, the spherical aberration and the field curvature can be moved to the positive side.

On the contrary, when the object has a concave non-linear trajectory, the ray L has the following properties. First, when the ray L diverges, the spherical aberration can be moved to the positive side, and when the ray L converges, the spherical aberration and the field curvature can be moved to the negative side. If the light ray L is substantially parallel to the optical axis,
The spherical aberration is almost constant regardless of the position of the third lens group G3, but the field curvature moves to the positive side when the third lens group G3 is moved to the object side, and to the image side when the third lens group G3 is moved to the image side. Move to the negative side. If such a property is used, the second lens group G2,
It is possible to remove aberration fluctuations that cannot be completely corrected by lens groups other than the third lens group G3. This is clear from the examples described later.

However, the second lens group G2 and the third lens group G
When the degree of freedom of aberration correction by lens groups other than 3 is sufficient, good imaging performance can be obtained even with a linear locus. In order to obtain even better performance, it is desirable to satisfy the following conditions in addition to the above-mentioned conditions. 0.5 <| f2-3 / fw <| 1 (4) 0.6 <f4 / | f5 | <1. 2 (5) 0.55 <f1 / | f2 | <1 (6) 0.8 <| f3 | / fW <2 (7) where, f1; focal length f2 of the first lens group G _1; second lens the focal length of the group G ₂ f3; third focal length of the lens unit G ₃ f2-3; combined focal length f4 at the wide angle end and the second lens group G ₂ and the third lens group G _3; fourth lens group G ₄ the focal length f5; focal length fW of the fifth lens group G _5; focal length condition of the entire zoom lens at the wide-angle end (4), the second lens group G2 and the third lens group G3
An appropriate ratio is determined for the combined focal length f2-3 at the wide-angle end and the focal length fW of the entire zoom lens at the wide-angle end. If the upper limit of conditional expression (4) is exceeded, fluctuations in coma aberration, field curvature, and astigmatism during zooming due to zooming become large, and for example, the fourth lens group G
It is difficult to secure sufficient back focus at the wide-angle end when the lens groups after 4 are considered to have the same configuration. vice versa,
When the lower limit of conditional expression (4) is exceeded, for example, the fourth lens group G
When the lens groups after the fourth lens group are the same, the total length at the wide-angle end becomes long, which is not only inconvenient, but also the lens diameter after the fourth lens group G4 becomes large, which is against compactness.

Conditional expression (5) defines an appropriate ratio for the focal length f4 of the fourth lens group G4 and the focal length f5 of the fifth lens group G5. If the upper limit of conditional expression (5) is exceeded, the focal length of the fifth lens group G5 becomes too short, the astigmatism at the wide-angle end becomes large, and the distortion aberration largely moves in the positive direction at the wide-angle end and the telephoto end. The Petzval sum is biased to the negative side, and a good aberration balance cannot be maintained during zooming due to zooming. On the other hand, if the lower limit of conditional expression (5) is exceeded, the focal length of the fourth lens group G4 becomes too short, and spherical aberration and coma will be large over the entire range during zooming. Further, when the fifth lens group G5 is the same, it becomes difficult to secure sufficient back focus.

Conditional expression (6) defines an appropriate ratio for the focal length f1 of the first lens group G1 and the focal length f2 of the second lens group G2. If the upper limit of conditional expression (6) is exceeded, the focal length of the second lens group G2 becomes too short,
For example, when the lens groups after the third lens group G3 have the same configuration, the total length at the wide-angle end becomes long, the lower coma at the wide-angle end becomes excessively large on the positive side, and the Petzval sum is biased on the negative side, which is inconvenient. is there. On the contrary, if the lower limit of conditional expression (6) is exceeded, the focal length of the second lens group G2 becomes too long, and the third lens group G2
When the lens groups after 3 are the same, it becomes difficult to secure sufficient back focus at the wide-angle end, and the fluctuation of the field curvature during zooming becomes large, which is inconvenient.

Conditional expression (7) defines an appropriate ratio for the focal length f3 of the third lens group G3 and the focal length fW at the wide-angle end. If the upper limit of conditional expression (7) is exceeded, the focal length of the third lens group G3 becomes too long,
If the fourth lens group G4 and the subsequent lens groups are the same, it is difficult to secure sufficient back focus at the wide-angle end, and the field curvature and coma aberration during zooming due to zooming become too large, which is inconvenient. Is. On the other hand, when the lower limit of conditional expression (7) is exceeded, the focal length of the second lens group G2 becomes too short. For example, when the fourth lens group G4 and subsequent lens groups have the same configuration, the total length at the wide-angle end is This is inconvenient because it becomes long and the lens diameter after the fourth lens group G4 becomes large.

Therefore, it is desirable to satisfy each of these conditional expressions. Further, in order to further improve the performance, it is desirable to satisfy the following conditions. 0.7 <TLT / fT <0.85 (8) −20 <βT3 / βW3 <10 (9) 0.7 <f2-3 / f5 <2.2 (10) However, TLT; full length at telephoto end fT Focal length at the telephoto end βT3; use magnification at the telephoto end of the third lens group G3 βW3; use magnification at the wide angle end of the third lens group G3 f2-3; wide angle between the second lens group G2 and the third lens group G3 Combined focal length f5 at end; focal length of fifth lens group G5 Conditional expression (8) defines an appropriate ratio with respect to the total length TLT and the focal length fT at the telephoto end. If the upper limit of conditional expression (8) is exceeded, the total length TLT at the telephoto end becomes long and the front lens diameter also becomes large, which is inconvenient. If the lower limit of conditional expression (8) is exceeded, the Petzval sum will be biased to the negative side, making it difficult to secure a sufficient back focus at the wide-angle end, which is inconvenient.

Conditional expression (9) defines an appropriate ratio between the use magnification βT3 at the wide-angle end and the use magnification βW3 at the telephoto end of the third lens group G3. If the range of conditional expression (9) is exceeded, fluctuations of various aberrations, especially fluctuations of field curvature become excessive, which is inconvenient. The conditional expression (10) is the combined focal length f2-3 of the second lens group G2 and the third lens group G3 at the wide-angle end.
And an appropriate ratio is set for the focal length f5 of the fifth lens group G5. For example, the second lens group G2,
When the lens groups other than the third lens group G3 and the fifth lens group G5 have the same structure, if the upper limit of conditional expression (10) is exceeded, the variation of coma aberration during zooming due to zooming becomes large, and overall There is a tendency toward coma, and it becomes difficult to secure sufficient back focus at the wide-angle end. On the other hand, if the lower limit of conditional expression (10) is exceeded, the total length at the wide-angle end becomes long, which is not only inconvenient, but also the space required for zooming by the fifth lens group G5 becomes difficult to obtain.

Further, the second lens group G2 and the third lens group G3
It is desirable that the following conditions be satisfied. Here, the shape factor q will be described first. Of the surfaces forming each lens group, the radius of curvature of the surface closest to the object is R
The shape factor q is as shown below, where a is the radius of curvature of the surface closest to the image side and is Rb. q = (Rb + Ra) / (Rb-Ra) In the following description, q2 and q3 are the second lens group G2 and
The shape factors when one lens or a cemented lens is used for each of the third lens groups G3 are shown. Here, when the refractive index and the Abbe number of the negative lens and the positive lens forming the second lens group G2 are N2−, N2 +, ν2−, and ν2 +, respectively, it is desirable to satisfy the following conditional expressions.

−0.3 <N2-−N2 + <0 (11) 5 <ν2-−ν2 + <20 (12) -1 <q2 <3 (13) When the upper limit of conditional expression (11) is exceeded, Petzval sum is obtained. Becomes excessive on the positive side, and it becomes difficult to correct the image plane. And the conditional expression (1
If the lower limit of 1) is exceeded, the Petzval sum will become too large on the negative side, making it difficult to correct field curvature.

If the upper limit of conditional expression (12) is exceeded, axial chromatic aberration will be undercorrected, making correction difficult. And the conditional expression
If the lower limit of (12) is exceeded, axial chromatic aberration will be overcorrected,
Good correction becomes difficult. If the range of conditional expression (13) is exceeded, spherical aberration will be overcorrected in the zooming area due to zooming, and the fluctuation of the field curvature during zooming due to zooming will be large, and good imaging performance will not be obtained.

Further, the Abbe numbers of the negative lens and the positive lens constituting the third lens group G3 are ν3− and ν3 +,
Refractive power of the cemented surface between the negative lens and the positive lens forming the third lens group G3, or the refractive power of the air gap (so-called air lens) between the negative lens and the positive lens forming the third lens group G3. When φ is φ, it is desirable to satisfy the following conditional expression.

0 <φ · f3 <2.0 (14) 5 <ν3 − −ν3 + <30 (15) −15 <q3 <0 (16) When the upper limit of conditional expression (14) is exceeded, the refractive power φ If it becomes too large, high-order aberrations will be generated and their fluctuations will be extremely large, and good imaging performance cannot be obtained. In particular, high-order spherical aberration at the telephoto end remarkably occurs on the positive side, and the fluctuation of the image plane becomes large, which is inconvenient. If the lower limit of conditional expression (14) is exceeded, not only the coma at the wide-angle end will be extremely large, but also the fluctuation of the image plane and the coma at the time of zooming due to zooming will be large, which is inconvenient.

If the upper limit of conditional expression (15) is exceeded, axial chromatic aberration will be undercorrected, making correction difficult. Conversely, conditional expression (15)
If the lower limit of is exceeded, the axial chromatic aberration is overcorrected, which makes correction difficult, which is not preferable. If the range of conditional expression (16) is exceeded, spherical aberration will be overcorrected in general, and the curvature of field will change greatly during zooming, which is undesirable because good imaging performance cannot be obtained.

The third lens group G3 and the fourth lens group G3 at the wide-angle end
It is desirable that the distance DW3-4 to the lens group G4 satisfies the following conditions. 0.2 <DW3-4 / fw <0.5 (17) For example, when the fifth lens group G5 has the same structure, if the upper limit of conditional expression (17) is exceeded, spherical aberration and coma will become extremely large. The correction becomes difficult. In addition, the fifth lens group G
This is inconvenient because the lens diameter of 5 becomes large and the total length becomes long. On the other hand, when the value goes below the lower limit, it becomes difficult to secure a space required for zooming, which is not suitable for high magnification. Further, at the wide-angle end, outward coma occurs, which makes it difficult to secure the back focus, which is inconvenient.

[0028]

EXAMPLES Each example according to the present invention will be described below. Example 1 FIG. 2 is a lens configuration diagram of Example 1,
A first lens group G including a cemented lens of a negative meniscus lens and a biconvex lens, and a positive lens in order from the object side.
₁ , a second lens group G ₂ of a cemented lens of a biconcave negative lens and a positive meniscus lens, a third lens group G ₃ of a cemented lens of a biconcave negative lens and a biconvex positive lens, and a negative meniscus A fourth lens group G ₄ including a lens, a biconvex lens, and a cemented lens including a biconvex lens and a negative meniscus lens,
The fifth lens group G _{5 is} composed of a cemented lens including a biconvex lens and a biconcave lens.

Table 1 below lists values of specifications of the first embodiment of the present invention. F in the specification table of the embodiment is the focal length,
F _NO is the F number and 2ω is the angle of view. The number at the left end represents the order from the object side, r is the radius of curvature of the lens surface, d is the lens surface spacing, refractive index n and Abbe number ν are values for the d line (λ = 587.6 nm).

[0030]

Table 1 Specifications of Example 1 f = 76.5 to 292 F _NO = 4.61 to 5.69 2ω = 33.04 to 8.1 ° (Variable spacing during zooming) F 76.5000 150.0000 292.0000 D0 ∞ ∞ ∞ d 5 1.7915 27.3961 62.8201 d 8 3.5488 19.7091 19.3674 d11 46.3521 15.6734 3.7959 d18 34.9130 23.8268 .6220 d21 38.3281 63.9327 99.3567 (Value corresponding to conditions) (1) f1 / (fw FT) ^1/2 = 0.8698 (2) f2 / f3 = 0.9935 (3) (DT2-3-DW2-3) / fW = 0.2068 (4) | f2-3 / fW | = 0 .91307 (5) f4 / | f5 | = 0.8219 (6) f1 / | f2 | = 0.93525 (7) | f3 | / fW = 1.882889 (8) TLT / fT = 0.79679 (9) ) ΒT3 / βW3 = -19.822 (10) f2-3 / f5 = 1.187732 (11) N2- -N2 + = -0.12456 (12) ν2--ν2 + = 13.699 (13) q2 =- 0.04017 (14) φ · f3 = 0.39175 (15) ν3-−ν3 + = 7.152 (16) q3 = 14.879 (17) DW2-3 / fw = 0.4563 FIGS. 3, 4 and 5 are graphs showing various aberrations at the wide-angle end, aberration graphs at the intermediate focal length state, and telephoto end of Example 1, respectively. The various aberration figures in a state are shown. As is clear from each aberration diagram, it is understood that various aberrations are satisfactorily corrected in this example.

In each aberration diagram, H is the incident height, FNO
Is the F number, Y is the image height, A is the incident angle of the chief ray, and d is d
The line (λ = 587.6 nm) and g are shown as the g line (λ = 435.6 nm). Example 2 FIG. 6 is a lens configuration diagram of Example 2,
From the object side, in order from the object side, a first lens group G ₁ consisting of a negative meniscus lens and a biconvex positive lens, a second lens group G ₂ of a cemented lens of a biconcave negative lens and a biconvex positive lens, and a biconcave negative lens. a third lens group G _3, biconvex lens, the fourth lens group G ₄ consisting of cemented lens of a double convex lens and a negative meniscus lens, a biconvex lens, and a fifth lens group G ₅ consisting of a biconcave lens ..

The second embodiment having the above-described structure is a lens applicable to the slightly short focus side, and has a simple lens structure such that the third lens group G3 is composed of one lens. Table 2 below lists values of specifications of Example 2 of the present invention. In the specification table of the embodiment, f is the focal length, F _NO is the F number, and 2ω
Represents the angle of view. The leftmost number represents the order from the object side, r is the radius of curvature of the lens surface, d is the lens surface interval,
The refractive index n and the Abbe number ν are values for the d line (λ = 587.6 nm).

[0033]

Table 2 Specifications of Example 2 f = 82 to 196 F _NO = 4.6 to 5.7 2ω = 29.66 to 12.16 ° (Variable interval during zooming) F 82.0000 135.0000 196.0000 D0 ∞ ∞ ∞ d 4 2.1562 23.7506 39.4991 d 7 4.1898 2.7190 8.8577 d 9 24.9438 14.6750 2.8315 d14 22.0952 12.2404 2.1968 d18 43.0664 64.6608 80.4093 (Value corresponding to condition) (1) f1 / (fw FT) ^1/2 = 0.87572 (2) f2 / f3 = 1.92046 (3) (DT2-3-DW2-3) /fW=0.0569 (4) | f2-3 / fW | = 0 .58 (5) f4 / | f5 | = 0.6544 (6) f1 / | f2 | = 0.765507 (7) | f3 | /fw=0.92146 (8) TLT / fT = 0.84164 (9) ) ΒT3 / βW3 = 7.62219 (10) f2-3 / f5 = 0.79665 (11) N2- -N2 + = -0.08517 (12) ν2- -ν2 + = 19.453 (13) q2 = 1. 87799 (16) q3 = -0.5227 (17) DW3-4 / fw = 0.2695 FIGS. 7, 8 and 9 6A and 6B are graphs showing various aberrations of Example 2 at the wide-angle end, at the intermediate focal length state, and at the telephoto end, respectively. As is clear from each aberration diagram, it is understood that various aberrations are satisfactorily corrected in this example.

In each aberration diagram, H is the incident height and FNO is
Is the F number, Y is the image height, A is the incident angle of the chief ray, and d is d
The line (λ = 587.6 nm) and g are shown as the g line (λ = 435.6 nm). Example 3 FIG. 10 is a lens configuration diagram of Example 3,
From the object side, in order from the object side, a first lens group G ₁ consisting of a negative meniscus lens and a biconvex positive lens, a second lens group G ₂ of a cemented lens of a biconcave negative lens and a biconvex positive lens, and a biconcave negative lens. And a third lens unit G _{3 of} No. 4, a biconvex positive lens, and a cemented lens of a biconvex positive lens and a negative meniscus lens.
It is composed of a lens group G ₄ and a fifth lens group G ₅ including a cemented lens of a positive lens having a strong convex surface on the image side and a biconcave lens.

The third embodiment has substantially the same configuration as the second embodiment described above, but the refractive power and shape of each group are different. Table 3 below lists values of specifications of the third embodiment of the present invention. In the specification table of the embodiment, f is the focal length, F _NO is the F number, and 2ω is the angle of view. The leftmost number represents the order from the object side, r is the radius of curvature of the lens surface, d is the lens surface spacing, refractive index n and Abbe number ν are d lines (λ = 587.6
nm).

[0036]

Table 3 Specifications of Example 3 f = 82 to 196 F _NO = 4.62 to 5.7 2ω = 29.24 to 12.08 ° (Variable interval during zooming) F 82.0000 135.0000 196.0000 D0 ∞ ∞ ∞ d 4 2.8064 24.7099 39.9550 d 7 2.9810 .5461 7.4257 d 9 24.5298 14.9373 2.7893 d14 23.3891 13.5130 3.5363 d17 40.6047 62.50817 77.7533 (Condition corresponding value) (1) f1 / ( fw ・ ft) ^1/2 = 0.85119
(2) f2 / f3 = 2.52866 (3) (DT2-3-DW2-3) /fw=0.0542 (4) | f2-3 / fw | = 0.56883 (5) f4 / | f5 | = 0.70795 (6) f1 / | f2 | = 0.60258 (7) | f3 | /fw=0.86366 (8) TLT / fT = 0.83091 (9) βT3 / βW3 = 8.141448 (10) ) F2-3 / f5 = 0.89343 (11) N2- -N2 + = -0.08765 (12) ν2- -ν2 + = 14.35 (13) q2 = 2.34549 (16) q3 = -0.62770 (17) DW3-4 / fw = 0.2852 FIGS. 11, 12, and 13 are graphs showing various aberrations at the wide-angle end, intermediate aberrations, and telephoto ends of Example 3, respectively. The various aberration figures are shown. As is clear from each aberration diagram, it is understood that various aberrations are satisfactorily corrected in this example.

In each aberration diagram, H is the incident height and FNO is
Is the F number, Y is the image height, A is the incident angle of the chief ray, and d is d
The line (λ = 587.6 nm) and g are shown as the g line (λ = 435.6 nm). Example 4 FIG. 14 is a lens configuration diagram of Example 4,
In order from the object side, a cemented lens of a negative meniscus lens having a convex surface facing the object side and a biconvex lens, a first lens group G ₁ composed of a positive lens, and a cemented lens of a biconcave negative lens and a positive meniscus lens The second lens group G ₂ and the third lens group G _{3 which} is a cemented lens of two negative meniscus lenses with the concave surface facing the object side, the negative meniscus lens, the biconvex positive lens, the biconvex positive lens and the object side. The fourth lens group G including a cemented lens with a negative meniscus lens having a concave surface
₄ and a fifth lens group G ₅ including a cemented lens including a biconvex positive lens and a biconcave negative lens.

The fourth embodiment having the above structure achieves excellent chromatic aberration correction. Example 4 of the present invention is shown in Table 4 below.
The values of the specifications of are listed. In the specification table of the embodiment, f is the focal length, F _NO is the F number, and 2ω is the angle of view. The number at the left end represents the order from the object side, r is the radius of curvature of the lens surface, d is the lens surface spacing, refractive index n and Abbe number ν are values for the d line (λ = 587.6 nm).

[0039]

Table 4 Specifications of Example 4 f = 102.5 to 292 F _NO = 4.62 to 5.69 2ω = 23.32 to 8.18 ° (Variable interval during zooming) F 102.5000 200.0000 292.0000 D0 ∞ ∞ ∞ d 5 7.8656 37.2463 58.5971 d 8 9.1243 17.6025 12.2821 d11 30.5065 8.5766 5.7116 d18 29.4990 13.5700 .4045 d21 38.7204 68.1010 89.4519 (1w1 / f1) FT) ^1/2 = 0.69363 (2) f2 / f3 = 0.95434 (3) (DT2-3 − DW2-3) / fW = 0.0308 (4) | f2-3 / fW | = 0 .82673 (5) f4 / | f5 | = 1.06853 (6) f1 / | f2 | = 0.71856 (7) | f3 | / fw = 1.70722 (8) TLT / fT = 0.73235 (9) ) ΒT3 / βW3 = -1.040 (10) f2-3 / f5 = 1.89152 (11) N2--N2 + =-0.04766 (12) ν2--ν2 + = 6.124 (13) q2 =- 0.87488 (14) φ · f3 = 0.049 (15) ν3-−ν3 + = 23.953 (16) q3 = 4.9623 (17) DW3-4 / fw = 0.28779 FIG. 15, FIG. 16 and FIG. 17 are aberration diagrams at the wide-angle end, aberration diagrams at the intermediate focal length state, and telephoto end, respectively, of the fourth embodiment. The various aberration figures in a state are shown. As is clear from each aberration diagram, it is understood that various aberrations are satisfactorily corrected in this example.

In each aberration diagram, H is the incident height and FNO is
Is the F number, Y is the image height, d is the d line (λ = 587.6 nm) and
g is shown as the g line (λ = 435.6 nm). Example 5 FIG. 18 is a lens configuration diagram of Example 5,
Negative meniscus ray with convex surface facing the object side in order from the object side
Lens with a biconvex lens, with a convex surface on the object side
First lens group G consisting of a positive meniscus lens directed toward
₁And biconcave negative lens, positive meniscus with convex surface facing the object side
Second lens group G composed of slens₂And a concave surface on the object side
3rd lens group G consisting of two negative meniscus lenses
₃And a negative meniscus lens with a concave surface facing the object side, the object
Positive meniscus lens with concave surface facing the side, biconvex positive lens,
The fourth lens consisting of a negative meniscus lens with a concave surface facing the object side
Lens group G_FourAnd a positive meniscus ray with a concave surface facing the object side.
5th lens group G consisting of a double-concave negative lens _FiveComposed of
is doing.

In the fifth embodiment, the lens group closest to the image side in the fourth lens group G4, the second lens group G2, the third lens group G3,
The fifth lens group G5 is characterized in that it is composed of a positive lens and a negative lens separately. Another feature is that the second lens group G2 linearly moves toward the object side and the third lens group G3 linearly moves toward the image side during zooming due to zooming from the wide-angle end to the telephoto end.

Table 5 below lists values of specifications of the fifth embodiment of the present invention. In the specification table of the embodiment, f is the focal length, F _NO is the F number, and 2ω is the angle of view. The leftmost number represents the order from the object side, r is the radius of curvature of the lens surface, and d
Is the lens surface distance, the refractive index n and the Abbe number ν are d lines (λ = 5
87.6 nm).

[0043]

Table 5 Specifications of Example 5 f = 102.5 to 292 F _NO = 4.56 to 6.00 2ω = 23.2 to 8.2 ° (Variable spacing during zooming) F 102.5004 200.0000 292.0000 D0 ∞ ∞ ∞ d 5 2.4471 29.8180 46.0605 d 9 20.5138 24.8355 27.4001 d13 25.7976 9.6483 3.0073 d21 27.7352 12.1918 .0258 d25 35.9784 64.7898 81.8871 (Condition corresponding value) (1) f1 / (f FT) ^1/2 = 0.6589 (2) f2 / f3 = 0.698 (3) (DT2-3-DW2-3) / fW = 0.06718 (4) | f2-3 / fW | = 0 .8252591 (5) f4 / | f5 | = 1.13998 (6) f1 / | f2 | = 0.7862 (7) | f3 | /fw=2.025854 (8) TLT / fT = 0.71226 (9) ) ΒT3 / βW3 = -0.7928 (10) f2-3 / f5 = 2.016194 (11) N2- -N2 + = -0.04766 (12) ν2- -ν2 + = 6.124 (14) φ ・ f3 = 1.802565 (15) ν3--ν3 + = 23.953 (17) DW3-4 / fw = 0.2705 19, 20, 21 show aberration diagrams at the wide angle end, respectively Example 5, an aberration diagram of aberrations in the intermediate focal length state, the aberration diagram of aberrations in the telephoto end state. As is clear from each aberration diagram, it is understood that various aberrations are satisfactorily corrected in this example.

In each aberration diagram, H is the incident height and FNO is
Is the F number, Y is the image height, A is the incident angle of the chief ray, and d is d
The line (λ = 587.6 nm) and g are shown as the g line (λ = 435.6 nm). In Examples 1 to 5, the moving ratio of the first lens group G1 to the fifth lens group G5 is 1. However, even when the moving ratio of the first lens group G1 and the fifth lens group G5 is not 1, the degree of freedom in design is increased and the design is facilitated, and therefore the requirements of the zoom lens of the present invention are not deviated.

[0045]

As described above, according to the present invention, the zoom lens as a whole can be composed of about 10 to 13 lenses, and a compact telephoto zoom lens having excellent image forming performance can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing the principle of the present invention.

2 is a lens configuration diagram of Example 1. FIG.

FIG. 3 is a diagram of various types of aberration at the wide-angle end of Example 1.

FIG. 4 is a diagram of various types of aberration in the intermediate focal length state of Example 1.

FIG. 5 is a diagram of various types of aberration at the telephoto end of the first example.

FIG. 6 is a lens configuration diagram of Example 2.

FIG. 7 is a diagram of various types of aberration at the wide-angle end of Example 2;

FIG. 8 is a diagram of various types of aberration in the intermediate focal length state of Example 2.

FIG. 9 is a diagram of various types of aberration at the telephoto end of the second embodiment.

FIG. 10 is a lens configuration diagram of Example 3.

FIG. 11 is a diagram of various types of aberration at the wide-angle end of Example 3.

FIG. 12 is a diagram of various types of aberration in the intermediate focal length state of Example 3.

FIG. 13 is a diagram of various types of aberration at the telephoto end of Example 3.

FIG. 14 is a lens configuration diagram of Example 4.

FIG. 15 is a diagram of various types of aberration at the wide-angle end of Example 4.

16 is a diagram of various types of aberration in the intermediate focal length state of Example 4. FIG.

FIG. 17 is a diagram of various types of aberration at the telephoto end of the fourth embodiment.

FIG. 18 is a lens configuration diagram of Example 5.

FIG. 19 is a diagram of various types of aberration at the wide-angle end of Example 5.

FIG. 20 is a diagram of various types of aberration in the intermediate focal length state of Example 5.

FIG. 21 is a diagram of various types of aberration at the telephoto end of the fifth embodiment.

[Explanation of sign]

 G1 ... First lens group G2 ... Second lens group G3 ... Third lens group G4 ... Fourth lens group G5 ... Fifth lens group S ...

Claims (1)

[Claims] 1. A first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from the object side.
It has a third lens group G3 having a negative refracting power, a fourth lens group G4 having a positive refracting power, and a fifth lens group G5 having a negative refracting power, and changes from the wide-angle end to the telephoto end. At the time of magnification, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 changes linearly or non-linearly, and the fourth lens group G4
In the zoom lens in which the lens groups move so that the distance between the fifth lens group G5 and the fifth lens group G5 decreases, the focal length of the first lens group G1 is f1, the focal length of the second lens group G2 is f2, and the third lens group is the third lens group. The focal length of the lens group G3 is f3, the focal length of the fourth lens group G4 is f4, the focal length of the fifth lens group G5 is f5, and the focal length of the entire zoom lens at the wide-angle end is fW, and the focal length of the zoom lens at the wide-angle end is f3. The distance between the second lens group G2 and the third lens group G3 is DW2-3, the focal length of the entire zoom lens at the telephoto end is fT, and the distance between the second lens group G2 and the third lens G3 at the telephoto end is When DT2-3 is set, 0.3 ≤ f1 / (fw · ft) ^1/2 ≤ 1.5 (1) 0.3 ≤ f2 / f3 ≤ 5 (2) 0.01 ≤ (DT2-3-DW2 -3) / fw ≤ 0.6 (3) Telephoto zoom lens to be considered.