JP6703887B2 - Zoom lens and imaging device - Google Patents

Description

The present invention relates to a zoom lens capable of ensuring good optical performance even when a change in environmental temperature occurs, and an image pickup apparatus including the zoom lens.

A large number of zoom lenses that can be used in an image pickup apparatus provided with a solid-state image pickup device such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal Oxide Semiconductor) have been proposed (see, for example, Patent Documents 1 and 2). ).

JP, 2011-154390, A Japanese Patent No. 4542933

2. Description of the Related Art In recent years, surveillance cameras and security cameras for the purpose of deterring crime and recording highly reliable evidence at all times have rapidly become popular. Surveillance cameras, security cameras, and the like are required to be smaller because the installation space is often limited. Therefore, a zoom lens mounted on an image pickup apparatus such as a surveillance camera or a security camera is also required to be simple and compact.

In addition, surveillance cameras and security cameras are often installed outdoors where the temperature changes greatly. For this reason, zoom lenses mounted on surveillance cameras and security cameras are required to maintain good optical performance with little fluctuation in focus position even when a sudden change in environmental temperature occurs.

However, although the zoom lens described in Patent Document 1 can change the magnification by about 10 times, it has a large number of lenses and the total length of the optical system is long, so that the zoom lens is compact especially in high-magnification shooting. Lack.

On the other hand, the zoom lens described in Patent Document 2 achieves high zooming with a simple configuration, but chromatic aberration correction at the telephoto end is insufficient. In addition, although the manufacturing cost is reduced by using a resin lens, the resolution is remarkably reduced when the environmental temperature changes, especially at the telephoto end, because the resin lens used has too strong a bending force. There's a problem.

The present invention, in order to solve the above-mentioned problems of the conventional technique, has a simple and compact configuration, but suppresses the focus position variation even when a sudden change in the environmental temperature occurs, and is good. An object of the present invention is to provide a zoom lens capable of ensuring excellent optical performance. Further, it is another object of the present invention to provide a small-sized, high-performance image pickup device that can obtain a good image even if the environmental temperature changes.

In order to solve the problems described above and achieve the object, a zoom lens according to the present invention includes a first lens group having a positive refractive power and a second lens having a negative refractive power, which are arranged in order from the object side. From the wide-angle end by moving the second lens group along the optical axis and changing the interval on the optical axis of each of the lens groups. In the zoom lens for zooming to the telephoto end, the first lens group includes at least one positive lens formed of a glass material having anomalous dispersion, and the third lens group includes at least one positive lens formed of resin. It is characterized by including a negative lens and satisfying the following conditional expression.
(1) 0<|fn/fp|≦0.5
However, fn is a focal length of at least one negative lens formed of resin included in the third lens group, and fp is at least formed of a glass material having anomalous dispersion included in the first lens group. The focal length of one positive lens is shown.

According to the present invention, there is provided a zoom lens having a simple and compact structure, which can suppress fluctuations in a focus position even when a sudden change in environmental temperature occurs and can secure good optical performance. can do.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(2) 0<Δθg, F<0.06
However, Δθg,F represents the anomalous dispersion of at least one positive lens formed of a glass material having anomalous dispersion contained in the first lens group. For the anomalous dispersion Δθg,F, the vertical axis is the partial dispersion ratio θg,F, and the horizontal axis is the Abbe's number νd for the d-line, and the coordinates of C7 (νd=60.49, θg,F= 0.5436) and the coordinates of F2 (νd=36.26, θg, F=0.5828) when the standard line is the point on the standard line corresponding to νd of each glass material and that glass material. It is the deviation from θg and F. Further, the partial dispersion ratios θg, F are defined by θg, F=(ng-nF)/(nF-nC), and ng, nF, and nC represent the refractive indices for the g-line, the F-line, and the C-line, respectively.

According to the present invention, it is possible to effectively correct axial chromatic aberration and further improve optical performance.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(3) 1.5≦β2T/β3T≦15.0
However, β2T represents the magnification of the second lens group at the telephoto end, and β3T represents the magnification of the third lens group at the telephoto end.

According to the present invention, the optical performance can be improved while keeping the total length of the optical system short.

Further, in the zoom lens according to the present invention, in the above invention, a fourth lens group is provided on the image side of the third lens group, and the image associated with zooming is obtained by moving the fourth lens group along the optical axis. It is characterized in that the fluctuation of the surface position is corrected and the following conditional expression is satisfied.
(4) −70.0≦β3W/β4W≦−4.0
However, β3W represents the magnification of the third lens group at the wide-angle end, and β4W represents the magnification of the fourth lens group at the wide-angle end.

According to the present invention, the optical performance can be improved by keeping the overall length of the optical system short and suppressing the aberration variation when correcting the image plane position due to the magnification change.

Furthermore, the zoom lens according to the present invention is characterized in that, in the above invention, the following conditional expression is satisfied.
(5) -10.0<(f4/f3)/(f2/ft)≤-5.0
Here, f4 is the focal length of the fourth lens group, f3 is the focal length of the third lens group, f2 is the focal length of the second lens group, and ft is the focal length of the entire optical system at the telephoto end.

According to the present invention, the overall length of the optical system can be kept short, and the sensitivity of aberrations to the processing error of the third lens group can be reduced to suppress aberration fluctuations due to manufacturing variations.

An image pickup apparatus according to the present invention is characterized by including the zoom lens according to the above invention, and a solid-state image pickup element that converts an optical image formed by the zoom lens into an electrical signal.

According to the present invention, it is possible to provide a small-sized and high-performance image pickup device that can obtain a good image even when the environmental temperature changes.

ADVANTAGE OF THE INVENTION According to the present invention, it is possible to secure good optical performance by suppressing the focus position variation even when a sudden change in the environmental temperature occurs even though the configuration is simple and compact. It is possible to provide a zoom lens.

Further, according to the present invention, there is an effect that it is possible to provide a small-sized and high-performance imaging device that can obtain a good image even if the environmental temperature changes.

It is a graph for demonstrating the abnormal dispersion property regarding a g line and an F line. 3 is a cross-sectional view taken along the optical axis showing the configuration of the zoom lens according to Example 1. FIG. FIG. 6 is a diagram of various types of aberration of the zoom lens according to the first example. 6 is a cross-sectional view taken along the optical axis showing the configuration of a zoom lens according to Example 2. FIG. FIG. 9 is a diagram of various types of aberration of the zoom lens according to the second example. FIG. 6 is a sectional view taken along the optical axis showing the configuration of a zoom lens according to Example 3; FIG. 9 is a diagram of various types of aberration of the zoom lens according to the third example. FIG. 9 is a cross-sectional view taken along the optical axis showing the configuration of the zoom lens according to example 4; FIG. 9 is a diagram of various types of aberration of the zoom lens according to the fourth example. FIG. 9 is a cross-sectional view taken along the optical axis showing the configuration of the zoom lens according to example 5; FIG. 9 is a diagram of various types of aberration of the zoom lens according to the fifth example. FIG. 9 is a cross-sectional view taken along the optical axis showing the configuration of the zoom lens according to example 6; FIG. 16 is a diagram of various types of aberration of the zoom lens according to the sixth example. FIG. 9 is a cross-sectional view taken along the optical axis showing the configuration of the zoom lens according to example 7; FIG. 16 is a diagram of various types of aberration of the zoom lens according to the example 7; It is a figure which shows an example of the imaging device provided with the zoom lens concerning this invention.

Hereinafter, preferred embodiments of a zoom lens and an image pickup apparatus according to the present invention will be described in detail.

Imaging devices such as surveillance cameras and security cameras, which have become widespread in recent years, are often installed in an environment in which the temperature is narrow and changes greatly in temperature. According to the present invention, a simple and compact configuration, which is optimal for such an image pickup apparatus, suppresses the focus position variation even when the environmental temperature changes, and secures good optical performance. The objective is to provide a zoom lens capable of doing the above. Therefore, in order to achieve such an object, the present invention sets various conditions as described below.

A zoom lens according to the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side. And are equipped with. Then, the second lens group is moved along the optical axis to change the distance between the lens groups on the optical axis, thereby varying the magnification from the wide-angle end to the telephoto end.

In addition, the first lens group includes at least one positive lens formed of a glass material having anomalous dispersion, the third lens group includes at least one negative lens formed of resin, and the third lens group , Fn is a focal length of at least one negative lens made of resin, and fp is a focal length of at least one positive lens made of a glass material having anomalous dispersion contained in the first lens group. Then, it is preferable that the following conditional expression is satisfied.
(1) 0<|fn/fp|≦0.5

When a zoom lens having a long focal length and a large zoom ratio is to be constructed, the ray height in the optical system becomes high and its change is likely to be large, so that axial chromatic aberration is particularly likely to occur remarkably. Therefore, in the zoom lens according to the present invention, axial chromatic aberration correction is effectively performed by providing at least one positive lens formed of a glass material having anomalous dispersion in the first lens group having the largest aperture. be able to. This effect is remarkable especially in the telephoto end state.

However, since a glass material having anomalous dispersion has a high temperature dependency of a refractive index, when a positive lens made of a glass material having anomalous dispersion is arranged in the first lens group, it particularly passes through the first lens group. When the ambient temperature changes in the telephoto end state in which the maximum luminous flux is changed, the focal length of the positive lens changes greatly, and the focus position of the entire optical system tends to change. Note that this tendency becomes more remarkable when the environmental temperature changes rapidly.

Therefore, in the zoom lens according to the present invention, in the third lens group, at least one negative lens made of resin having a higher refractive index temperature dependency than the glass material is arranged. Then, the focal length of at least one positive lens formed of a glass material having anomalous dispersion included in the first lens group and at least one negative lens formed of resin included in the third lens group By appropriately setting the ratio to the focal length of the lens so as to satisfy the above conditional expression (1), it is possible to suppress fluctuations in the focusing position that occur when the environmental temperature changes and to ensure good optical performance. I chose

That is, in the zoom lens according to the present invention, fluctuations in the focal length of the positive lens formed of the glass material having anomalous dispersion in the first lens group when the environmental temperature changes are measured by the resin in the third lens group. It is possible to correct by changing the focal length of the negative lens formed in 1 above, suppress the focus position fluctuation, and ensure good optical performance.

The zoom lens according to the present invention satisfies the conditional expression (1) on the premise of the above configuration, so that the zoom lens has a simple and compact configuration, and even if a sudden change in environmental temperature occurs, It becomes possible to suppress the fluctuation of the focal position and secure good optical performance.

When the upper limit of conditional expression (1) is exceeded, the refractive power of the negative lens formed of resin in the third lens group becomes too weak, and the glass material having anomalous dispersion in the first lens group when the environmental temperature changes. It becomes impossible to suppress the variation of the in-focus position of the entire optical system due to the variation of the focal length of the positive lens formed in Step 2. Conditional expression (1) defines the absolute value of the ratio of the focal lengths of the two lenses, and therefore the numerical value cannot be 0 or less.

If the above conditional expression (1) satisfies the following range, a more preferable effect can be expected.
(1a) 0.3≦|fn/fp|≦0.5

In the zoom lens according to the present invention, it is preferable that the first lens group includes at least a negative lens, a positive lens, and a positive lens arranged in order from the object side. At least two positive lenses are required, but at least one made of a glass material having anomalous dispersion is sufficient. In the first lens group, it is preferable that the negative lens arranged closest to the object side and the positive lens arranged subsequently thereto be arranged close to each other or be cemented to each other. By doing so, axial chromatic aberration and lateral chromatic aberration can be favorably corrected. Further, by disposing the positive lens closest to the image side in the first lens group, it is possible to excellently correct astigmatism and distortion at the wide-angle end.

It is preferable that the second lens group is configured by arranging at least two negative lenses and one positive lens in this order from the object side. By doing so, it is possible to excellently correct field curvature and lateral chromatic aberration, especially at the wide-angle end.

It is preferable that the third lens group includes at least a positive lens and a negative lens arranged in order from the object side. By doing so, spherical aberration and field curvature can be corrected well. As described above, at least one negative lens made of resin is required.

In the zoom lens according to the present invention, a positive lens formed of a glass material having anomalous dispersion is arranged in the first lens group in order to correct axial chromatic aberration that is most concerned with ensuring optical performance. This is to do it. In order to carry out the axial chromatic aberration more effectively, it is necessary to properly set the anomalous dispersion of light in the short wavelength region of the glass material of the positive lens.

Before describing the anomalous dispersion, the partial dispersion ratio will be described first. The partial dispersion ratio is a value obtained by dividing the partial dispersion by the main dispersion. The main dispersion means a difference in refractive index between two reference wavelengths, and the partial dispersion means a difference in refractive index between other two wavelengths.

Here, each spectral line and its wavelength are set to g line (435.83 nm), F line (486.13 nm), d line (587.56 nm), C line (656.27 nm), and arbitrary characters x and y When corresponding to each spectrum line, the respective refractive indices for the x-ray and the y-ray are defined as nx and ny. For example, the refractive index for the d line is represented by nd, and the refractive index for the F line is represented as nF. Further, when the partial dispersion ratio for x-rays and y-rays is θx,y, θx,y=(nx−ny)/(nF−nC) is defined. For example, the partial dispersion ratio θg,F for the g-line and the F-line can be expressed as θg,F=(ng-nF)/(nF-nC).

Next, the anomalous dispersion will be described. In general optical materials, the partial dispersion ratio changes almost in the same tendency as the Abbe number changes, that is, when a graph is created with the Abbe number as the horizontal axis and the partial dispersion ratio as the vertical axis, Has the property of riding. At this time, what does not ride on the straight line is called anomalous dispersion.

Here, the anomalous dispersion of g-line and F-line will be described. FIG. 1 is a graph for explaining the anomalous dispersion of g-line and F-line. As shown in FIG. 1, first, on the XY coordinate plane, the Abbe number νd for the d line is taken as the x axis, and the partial dispersion ratio θg,F for the g line and the F line is taken as the Y axis. The coordinate planes with respect to the two reference glass materials C7 (νd=60.49, θg, F=0.5436) and F2 (νd=36.26, θg, F=0.5828) for the g-line and the F-line. The upper two points are defined, and the straight line connecting the two points is defined as “standard line gF regarding the g line and the F line”. In the present invention, the standard line gF is defined as “a straight line having a slope of −0.0016 and an intercept of 0.6415, “standard line gF: θg, F=0.6415-0.0016×νd”. As a result, the anomalous dispersion of the g-line and the F-line is calculated as follows: The deviation Δθg,F of θg,F from the standard line gF is the value of the anomalous dispersion for a given glass material (νd,θg,F). Can be defined. For example, when the Abbe number for a d-line of an arbitrary glass material is νd and the partial dispersion ratio θg,F for a g-line and an F-line, the anomalous dispersion Δθg,F for the g-line and F-line of the glass material is Δθg,F =?g,F-(0.6415-0.0016x?d). Δθg,F defined in this way represents anomalous dispersion of g-line and F-line.

In the zoom lens according to the present invention, the following conditional expression is satisfied when the anomalous dispersion of at least one positive lens formed of a glass material having anomalous dispersion included in the first lens group is Δθg,F. Preferably.
(2) 0<Δθg, F<0.06

By satisfying conditional expression (2), axial chromatic aberration correction (in particular, telephoto end state) can be more effectively performed, and optical performance can be further improved. In the zoom lens according to the present invention, when the anomalous dispersion of at least one positive lens formed of the glass material having anomalous dispersion included in the first lens group deviates from the range defined by the conditional expression (2), The effect of correcting axial chromatic aberration may be weakened.

It should be noted that if the conditional expression (2) satisfies the following range, a more preferable effect can be expected.
(2a) 0.02≦Δθg, F≦0.05

Further, in the zoom lens according to the present invention, when the magnification of the second lens group at the telephoto end is β2T and the magnification of the third lens group at the telephoto end is β3T, it is preferable to satisfy the following conditional expression.
(3) 1.5≦β2T/β3T≦15.0

Conditional expression (3) defines the ratio between the magnification of the second lens group at the telephoto end and the magnification of the third lens group at the telephoto end. By satisfying the conditional expression (3), it is possible to improve the optical performance while keeping the total length of the optical system short.

If the lower limit of conditional expression (3) is not reached, the magnification of the second lens group will be too small compared to the third lens group. As a result, the power of the second lens group becomes insufficient, and the amount of movement of the second lens group at the time of zooming increases, so that the overall length of the optical system is extended and it becomes difficult to downsize the entire optical system. On the other hand, if the upper limit of conditional expression (3) is exceeded, the magnification of the second lens group becomes too large compared to the third lens group, and the occurrence of various aberrations becomes noticeable. In order to solve this, it becomes necessary to add a further lens to the second lens group, which also makes it difficult to downsize the entire optical system.

In addition, if the conditional expression (3) satisfies the following range, a more preferable effect can be expected.
(3a) 2.0≦β2T/β3T≦13.0

Further, in the zoom lens according to the present invention, the fourth lens group is provided on the image side of the third lens group, and the fourth lens group is moved along the optical axis to correct the image plane position due to zooming. Good to do. Further, in the zoom lens according to the present invention, the magnification of the third lens group at the wide-angle end is β3W, and the fourth lens at the wide-angle end is the fourth lens, on the assumption that the fourth lens group is arranged on the image side of the third lens group. When the magnification of the group is β4W, it is preferable to satisfy the following conditional expression.
(4) −70.0≦β3W/β4W≦−4.0

Conditional expression (4) defines the ratio between the magnification of the third lens group at the wide-angle end and the magnification of the fourth lens group at the wide-angle end. By satisfying the conditional expression (4), the optical system overall length is kept short, and the aberration variation caused when correcting the image plane position due to the zooming in the fourth lens group is suppressed to improve the optical performance. Can be made

If the lower limit of conditional expression (4) is not reached, the magnification of the fourth lens group becomes too small as compared with the third lens group. As a result, the amount of movement of the fourth lens unit increases when the image plane position is corrected, so that the overall length of the optical system is extended, making it difficult to downsize the entire optical system. On the other hand, when the upper limit of conditional expression (4) is exceeded, the magnification of the fourth lens group becomes too large as compared with the third lens group, and the aberration fluctuation during correction of the image plane position by the fourth lens group becomes large. Therefore, it is not preferable.

In addition, if the conditional expression (4) satisfies the following range, a more preferable effect can be expected.
(4a) −60.0≦β3W/β4W≦−7.0

It is preferable that the fourth lens group includes at least one cemented lens including a positive lens and a negative lens. By doing so, it is possible to satisfactorily correct chromatic aberration that occurs when the fourth lens group corrects the image plane position due to zooming.

Further, in the zoom lens according to the present invention, the focal length of the fourth lens unit is f4, the focal length of the third lens unit is f3, the focal length of the second lens unit is f2, and the focal length of the entire optical system at the telephoto end. When ft is ft, it is preferable to satisfy the following conditional expression.
(5) -10.0<(f4/f3)/(f2/ft)≤-5.0

Conditional expression (5) is defined by (ratio between the focal length of the fourth lens group and the focal length of the third lens group) and (ratio between the focal length of the second lens group and the focal length of the entire optical system at the telephoto end. ) Is to define the relationship with. By satisfying the conditional expression (5), it is possible to keep the total length of the optical system short, reduce the aberration sensitivity to the processing error of the third lens group, and suppress the aberration fluctuation caused by the manufacturing variation. ..

If the lower limit of conditional expression (5) is not reached, the power of the third lens group in the entire optical system will be too strong, and the sensitivity of aberrations of the third lens group to processing errors will be too great. It becomes impossible to suppress variation in aberration due to variation. On the other hand, if the upper limit of conditional expression (5) is exceeded, the power of the second lens group in the entire optical system becomes too weak, and the amount of movement of the second lens group during zooming increases, thereby increasing the total length of the optical system. And it becomes difficult to downsize the entire optical system.

In addition, if the conditional expression (5) satisfies the following range, a more preferable effect can be expected.
(5a) −8.5≦(f4/f3)/(f2/ft)≦−5.5

Further, in the zoom lens according to the present invention, the fifth lens group may be arranged on the image side of the fourth lens group to correct astigmatism.

Further, in the zoom lens according to the present invention, the average value of the refractive index change with respect to the d-line per 1° C. temperature change in at least one positive lens formed of a glass material having anomalous dispersion contained in the first lens group. Is (dt/dT)p, and the average value of the refractive index change with respect to the d-line per 1° C. temperature change in at least one negative lens formed of resin included in the third lens group is (dt/dT)n. Then, it is preferable that the following conditional expression is satisfied.
^{(6) -8 × 10- 6 <} (dt / dT) p <-4 × 10- 6
^{(7) -150 × 10- 6 <} (dt / dT) n <-50 × 10- 6

By satisfying the conditional expressions (6) and (7), it is possible to further improve the effect of suppressing the focus position variation when the environmental temperature changes.

As described above, according to the present invention, by providing the above-described configuration, it is possible to suppress the focus position fluctuation even when a rapid change in the environmental temperature occurs even though the configuration is simple and compact. Thus, it is possible to realize a zoom lens capable of ensuring good optical performance.

The zoom lens according to the present invention having such characteristics is suitable not only for a small-sized image pickup apparatus installed in a narrow space, but also for a surveillance camera which is often installed outdoors in which the temperature changes greatly. It is suitable for imaging devices such as security cameras.

Another object of the present invention is to provide a small-sized, high-performance imaging device that can obtain a good image even if the environmental temperature changes. In order to achieve this object, an image pickup apparatus may be configured to include a zoom lens having the above configuration and a solid-state image pickup element that converts an optical image formed by this zoom lens into an electrical signal. By doing so, it is possible to realize a small-sized and high-performance imaging device that can obtain a good image even if the environmental temperature changes.

Embodiments of a zoom lens according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the examples below.

FIG. 2 is a sectional view taken along the optical axis showing the configuration of the zoom lens according to the first example. The figure shows the wide-angle end state of the optical system. This zoom lens includes, in order from the object side (not shown), a first lens group G ₁₁ having a positive refractive power, a second lens group G ₁₂ having a negative refractive power, and a third lens group having a positive refractive power. G ₁₃ , a fourth lens group G ₁₄ having a positive refractive power, and a fifth lens group G ₁₅ having a negative refractive power are arranged and configured. An aperture stop STOP that defines a predetermined aperture is arranged between the second lens group G ₁₂ and the third lens group G ₁₃ . IMG indicates the image plane.

The first lens group G ₁₁ is configured by arranging a negative lens L ₁₁₁ , a positive lens L _112, and a positive lens L _{113 in} order from the object side. The negative lens L ₁₁₁ and the positive lens L ₁₁₂ are cemented together. The positive lens L ₁₁₂ is made of a glass material having anomalous dispersion. In the positive lens L ₁₁₂ without a positive lens L ₁₁₃ may be formed of a glass material having anomalous dispersion.

The second lens group G ₁₂ is composed of a negative lens L ₁₂₁ , a negative lens L _122, and a positive lens L ₁₂₃ arranged in this order from the object side.

The third lens group G ₁₃ is configured by arranging a positive lens L ₁₃₁ and a negative lens L _{132 in this} order from the object side. Aspherical surfaces are formed on both surfaces of each of the positive lens L ₁₃₁ and the negative lens L ₁₃₂ . The negative lens L ₁₃₂ is made of resin.

The fourth lens group G ₁₄ is composed of a positive lens L ₁₄₁ and a negative lens L ₁₄₂ arranged in order from the object side. An aspherical surface is formed on the object side surface of the positive lens L ₁₄₁ . The positive lens L ₁₄₁ and the negative lens L ₁₄₂ are cemented together.

The fifth lens group G ₁₅ is composed of one negative lens L ₁₅₁ . Aspherical surfaces are formed on both surfaces of the negative lens L ₁₅₁ .

In this zoom lens, the first lens group G ₁₁ , the aperture stop STOP, the third lens group G ₁₃ , and the fifth lens group G ₁₅ are fixed to the image plane IMG, and the second lens group G ₁₂ is used as the optical axis. By moving from the object side to the image plane IMG side along the distance from the wide-angle end to the telephoto end so that the fourth lens group G ₁₄ forms a convex locus along the optical axis toward the object side. By moving it, the image plane position variation due to the magnification change is corrected.

Hereinafter, various numerical data regarding the zoom lens according to the example 1 will be shown.

(Surface data)
r ₁ =60.728
d ₁ =1.20 nd ₁ =1.92119 νd ₁ =24.0
r ₂ =34.316
d ₂ =7.55 nd ₂ =1.49700 νd ₂ =81.5
r ₃ =-211.257
d ₃ =0.10
r ₄ =30.354
d ₄ =4.45 nd ₃ =1.77250 νd ₃ =49.6
r ₅ = 88.992
d ₅ =D(5) (variable)
r ₆ = 79.636
_{d 6 = 0.70 nd 4 = 1.83481} νd 4 = 42.7
r ₇ =6.869
d ₇ =3.80
r ₈ =-24.317
_{d 8 = 0.50 nd 5 = 1.88100} νd 5 = 40.1
r ₉ =23.317
d ₉ =0.10
r ₁₀ = 14.599
d ₁₀ =2.25 nd ₆ =1.94594 νd ₆ =18.0
r ₁₁ =164.499
d ₁₁ =D(11) (variable)
r ₁₂ =∞ (aperture stop)
d ₁₂ =0.50
r ₁₃ = 10.897 (aspherical surface)
d ₁₃ =4.63 nd ₇ =1.58313 νd ₇ =59.5
r ₁₄ =-44.476 (aspherical surface)
d ₁₄ =0.24
r ₁₅ = 13.384 (aspherical surface)
d ₁₅ =2.75 nd ₈ =1.63980 νd ₈ =23.3
r ₁₆ =6.416 (aspherical surface)
d ₁₆ =D(16) (variable)
r ₁₇ =10.931 (aspherical surface)
d ₁₇ =4.20 nd ₉ =1.49710 νd ₉ =81.6
r ₁₈ =-9.700
d ₁₈ =0.60 nd ₁₀ =1.90366 νd ₁₀ =31.3
r ₁₉ =-13.847
d ₁₉ =D(19) (variable)
r ₂₀ =-11.755 (aspherical surface)
d ₂₀ =0.56 nd ₁₁ =1.58 250 νd ₁₁ =30.2
r ₂₁ =-14.809 (aspherical surface)
d ₂₁ =BF
r ₂₂ =∞ (image plane)

Cone coefficient (ε) and aspherical coefficient (A, B, C, D, E)
(Thirteenth surface)
ε=1.0000,
A=0, B=-7.2882×10 ^-5 , C=-4.3617×10 ^-7 ,
D=-2.0473×10 ^-8 , E=5.1896×10 ^-10
(14th surface)
ε=1.0000,
A=0, B=1.6098×10 ^-5 , C=-1.9490×10 ^-6 ,
D=5.4208×10 ^-8 , E=1.8539×10 ^-10
(15th surface)
ε=1.0000,
A=0, B=-2.2787×10 ^-4 , C=-3.9391×10 ^-6 ,
D=9.4991×10 ^-8 , E=4.7313×10 ^-10
(16th surface)
ε=1.0000,
A=0, B=-4.7306×10 ^-4 , C=-8.1671×10 ^-6 ,
D=-1.2150×10 ^-7 , E=2.5816×10 ^-9
(17th surface)
ε = 0.6794,
A=0, B=-8.1342×10 ^-5 , C=-1.3622×10 ^-6 ,
D = 1.0986 x 10 ^-8 , E = 1.7008 x 10 ^-10
(20th surface)
ε=1.0000,
A=0, B=2.8206×10 ^-3 , C=-1.3776×10 ^-5 ,
D=-1.1327×10 ^-6 , E=-4.3454×10 ^-8
(21st surface)
ε=1.0000,
A=0, B=2.8343×10 ^-3 , C=7.3832×10 ^-6 ,
D=-1.7557×10 ^-6 , E=-6.6363×10 ^-8

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 4.78 21.57 97.16
F number 1.66 2.97 4.00
Half angle of view (ω) 33.51 7.79 1.73
D(5) 0.77 20.67 30.89
D(11) 31.71 11.82 1.60
D(16) 7.95 3.81 11.18
D(19) 4.42 8.57 1.20
Back focus (BF) (air conversion length) 5.53 5.54 5.60

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 44.99 0.00
26 -7.81 30.12
3 13 25.65 0.00
4 17 15.23 -3.23
5 20 -104.89 0.00

(Numerical value regarding conditional expression (1))
fn (focal length of negative lens L ₁₃₂ formed of resin)=-22.76
fp (focal length of the positive lens L ₁₁₂ formed of a glass material having anomalous dispersion)=60.01
|fn/fp|=0.38

(Numerical value regarding conditional expression (2))
Δθg, F=0.028
Δθg,F: Anomalous dispersion of positive lens L ₁₁₂

(Numerical value regarding conditional expression (3))
β2T (magnification of the second lens group G ₁₂ at the telephoto end)=−7.56
β3T (magnification of the third lens group G ₁₃ at the telephoto end)=−0.62
β2T/β3T=12.18

(Numerical value regarding conditional expression (4))
β3W (magnification of third lens group G ₁₃ at wide-angle end)=-1.77
β4W (magnification of the fourth lens group G ₁₄ at the wide-angle end)=0.22
β3W/β4W=-7.95

(Numerical value regarding conditional expression (5))
(F4/f3)/(f2/ft)=-7.39

(Numerical value regarding conditional expression (6))
(Dt/dT)p=-7.7×10 ^-6
(Dt/dT)p: average value of change in refractive index with respect to d line per 1° C. temperature change in the positive lens L ₁₁₂

(Numerical value regarding conditional expression (7))
(Dt/dT) n=-77.1×10 ^-6
(Dt/dT)n: Average value of change in refractive index with respect to d line per 1° C. temperature change in the negative lens L ₁₃₂

FIG. 3 is a diagram of various types of aberration of the zoom lens according to the first example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the C line (656.27 nm), and the long broken line is the g line (435. The characteristics of the wavelength corresponding to (83 nm) are shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

FIG. 4 is a sectional view taken along the optical axis, showing the configuration of the zoom lens according to the second example. The figure shows the wide-angle end state of the optical system. This zoom lens includes, in order from the object side (not shown), a first lens group G ₂₁ having a positive refractive power, a second lens group G ₂₂ having a negative refractive power, and a third lens group having a positive refractive power. G ₂₃ , a fourth lens group G ₂₄ having a positive refractive power, and a fifth lens group G ₂₅ having a negative refractive power are arranged and configured. An aperture stop STOP that defines a predetermined aperture is arranged between the second lens group G ₂₂ and the third lens group G ₂₃ . IMG indicates the image plane.

The first lens group G ₂₁ includes a negative lens L ₂₁₁ , a positive lens L _212, and a positive lens L ₂₁₃ , which are arranged in this order from the object side. The negative lens L ₂₁₁ and the positive lens L ₂₁₂ are cemented together. The positive lens L ₂₁₂ is made of a glass material having anomalous dispersion. The positive lens L ₂₁₃ may be formed of a glass material having anomalous dispersion, instead of the positive lens L ₂₁₂ .

The second lens group G ₂₂ is configured by arranging a negative lens L ₂₂₁ , a negative lens L _222, and a positive lens L _{223 in} order from the object side.

The third lens group G ₂₃ is configured by arranging a positive lens L ₂₃₁ and a negative lens L _{232 in} order from the object side. Aspherical surfaces are formed on both surfaces of each of the positive lens L ₂₃₁ and the negative lens L ₂₃₂ . The negative lens L ₂₃₂ is made of resin.

The fourth lens group G ₂₄ is configured by arranging a positive lens L ₂₄₁ and a negative lens L _{242 in} order from the object side. An aspherical surface is formed on the object side surface of the positive lens L ₂₄₁ . The positive lens L ₂₄₁ and the negative lens L ₂₄₂ are cemented together.

The fifth lens group G ₂₅ is configured by arranging a positive lens L ₂₅₁ and a negative lens L _{252 in this} order from the object side. Aspherical surfaces are formed on both surfaces of the positive lens L ₂₅₁ .

In this zoom lens, the first lens group G ₂₁ , the aperture stop STOP, the third lens group G ₂₃ , and the fifth lens group G ₂₅ are fixed with respect to the image plane IMG, and the second lens group G ₂₂ is used as the optical axis. By moving from the object side to the image plane IMG side along the distance from the wide-angle end to the telephoto end so that the fourth lens group G ₂₄ forms a convex locus on the object side along the optical axis. By moving it, the image plane position variation due to the magnification change is corrected.

Hereinafter, various numerical data regarding the zoom lens according to the second embodiment will be shown.

(Surface data)
r ₁ =61.923
d ₁ =1.20 nd ₁ =1.92119 νd ₁ =24.0
r ₂ =34.741
d ₂ =7.21 nd ₂ =1.49700 νd ₂ =81.5
r ₃ =-205.016
d ₃ =0.10
r ₄ =30.544
d ₄ =4.53 nd ₃ =1.77250 νd ₃ =49.6
r ₅ =90.693
d ₅ =D(5) (variable)
r ₆ =121.759
_{d 6 = 0.70 nd 4 = 1.83481} νd 4 = 42.7
r ₇ =6.957
d ₇ =3.55
r ₈ =-24.613
_{d 8 = 0.50 nd 5 = 1.88100} νd 5 = 40.1
r ₉ =24.613
d ₉ =0.10
r ₁₀ = 14.525
d ₁₀ =2.24 nd ₆ =1.94594 νd ₆ =18.0
r ₁₁ =178.615
d ₁₁ =D(11) (variable)
r ₁₂ =∞ (aperture stop)
d ₁₂ =0.50
r ₁₃ = 10.903 (aspherical surface)
d ₁₃ =4.63 nd ₇ =1.58313 νd ₇ =59.5
r ₁₄ =-56.704 (aspherical surface)
d ₁₄ =1.55
r ₁₅ = 16.266 (non-spherical)
d ₁₅ =2.81 nd ₈ =1.63980 νd ₈ =23.3
r ₁₆ =6.955 (aspherical surface)
d ₁₆ =D(16) (variable)
r ₁₇ = 10.456 (aspherical surface)
d ₁₇ =4.20 nd ₉ =1.49710 νd ₉ =81.6
r ₁₈ = -9.577
d ₁₈ =0.60 nd ₁₀ =1.90366 νd ₁₀ =31.3
r ₁₉ =-13.542
d ₁₉ =D(19) (variable)
r ₂₀ =-19.484 (aspherical surface)
_{d 20 = 0.77 nd 11 = 1.58250} νd 11 = 30.2
r ₂₁ = -17.764 (aspherical surface)
d ₂₁ =0.10
r ₂₂ = -21.122
_{d 22 = 0.91 nd 12 = 1.49700} νd 12 = 81.6
r ₂₃ = -27.843
d ₂₃ =BF
r ₂₄ =∞ (image plane)

Cone coefficient (ε) and aspherical coefficient (A, B, C, D, E)
(Thirteenth surface)
ε=1.0000,
A=0, B=-7.6547×10 ^-5 , C=9.1977×10 ^-8 ,
D=-2.7566×10 ^-8 , E=7.1212×10 ^-10
(14th surface)
ε=1.0000,
A=0, B=1.5869×10 ^-5 , C=-2.0079×10 ^-6 ,
D=6.1456×10 ^-8 , E=1.5724×10 ^-10
(15th surface)
ε=1.0000,
A=0, B=-1.6988×10 ^-4 , C=-8.8562×10 ^-6 ,
D=3.2196×10 ^-7 , E=-3.2112×10 ^-9
(16th surface)
ε=1.0000,
A=0, B=-3.3427×10 ^-4 , C=-1.4652×10 ^-5 ,
D=4.4818×10 ^-7 , E=-8.2416×10 ^-9
(17th surface)
ε=0.5700,
A=0, B=-9.4508×10 ^-5 , C=-1.3288×10 ^-6 ,
D=5.0221×10 ^-8 , E=-1.0536×10 ^-9
(20th surface)
ε=1.0000,
A=0, B=8.0 058×10 ⁻⁴ , C=−2.0366×10 ⁻⁵ ,
D=-9.6966×10 ^-7 , E=1.9053×10 ^-8
(21st surface)
ε=1.0000,
A=0, B=8.0124×10 ^-4 , C=-1.0402×10 ^-5 ,
D=-2.5393×10 ^-6 , E=6.7357×10 ^-8

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 4.78 21.57 97.16
F number 1.63 2.97 4.07
Half angle of view (ω) 34.28 7.91 1.75
D(5) 0.87 20.91 31.01
D(11) 32.23 12.19 2.10
D(16) 8.22 3.88 11.37
D(19) 4.70 9.04 1.55
Back focus (BF) (air conversion length) 4.47 4.48 4.58

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 45.08 0.00
26-7.83 30.14
3 13 26.86 0.00
4 17 14.63 -3.15
5 20 -461.60 0.00

(Numerical value regarding conditional expression (1))
fn (focal length of negative lens L ₂₃₂ formed of resin)=-21.53
fp (focal length of positive lens L ₂₁₂ formed of a glass material having anomalous dispersion)=60.37
|fn/fp|=0.36

(Numerical value regarding conditional expression (2))
Δθg, F=0.028
Δθg, F: Anomalous dispersion of positive lens L ₂₁₂

(Numerical value regarding conditional expression (3))
β2T (magnification of the second lens group G ₂₂ at the telephoto end)=−7.16
β3T (magnification of third lens group G ₂₃ at telephoto end)=−0.76
β2T/β3T=9.47

(Numerical value regarding conditional expression (4))
β3W (magnification of third lens group G ₂₃ at wide-angle end)=−2.33
β4W (magnification of fourth lens group G ₂₄ at wide-angle end)=0.18
β3W/β4W=-13.26

(Numerical value regarding conditional expression (5))
(F4/f3)/(f2/ft)=-6.76

(Numerical value regarding conditional expression (6))
(Dt/dT)p=-7.7×10 ^-6
(Dt/dT)p: average value of change in refractive index with respect to d line per 1° C. temperature change in the positive lens L ₂₁₂

(Numerical value regarding conditional expression (7))
(Dt/dT) n=-77.1×10 ^-6
(Dt/dT)n: Average value of change in refractive index with respect to d line per 1° C. temperature change in the negative lens L ₂₃₂ .

FIG. 5 is a diagram of various types of aberration of the zoom lens according to the second example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the C line (656.27 nm), and the long broken line is the g line (435. The characteristics of the wavelength corresponding to (83 nm) are shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

FIG. 6 is a sectional view taken along the optical axis, showing the configuration of the zoom lens according to the third example. The figure shows the wide-angle end state of the optical system. This zoom lens includes a first lens group G ₃₁ having a positive refractive power, a second lens group G ₃₂ having a negative refractive power, and a third lens group having a positive refractive power in order from the object side (not shown). G ₃₃ , a fourth lens group G ₃₄ having a positive refractive power, and a fifth lens group G ₃₅ having a negative refractive power are arranged and configured. An aperture stop STOP that defines a predetermined aperture is arranged between the second lens group G ₃₂ and the third lens group G ₃₃ . IMG indicates the image plane.

The first lens group G ₃₁ includes, in order from the object side, a negative lens L ₃₁₁ , a positive lens L _312, and a positive lens L ₃₁₃ . The negative lens L ₃₁₁ and the positive lens L ₃₁₂ are cemented together. The positive lens _L312 is made of a glass material having anomalous dispersion. The positive lens L ₃₁₃ may be formed of a glass material having anomalous dispersion, instead of the positive lens L ₃₁₂ .

The second lens group G ₃₂ is configured by arranging a negative lens L ₃₂₁ , a negative lens L _322, and a positive lens L _{323 in this} order from the object side.

The third lens group G ₃₃ includes a positive lens L ₃₃₁ , a negative lens L _332, and a negative lens L ₃₃₃ , which are arranged in this order from the object side. Aspherical surfaces are formed on both surfaces of the positive lens L ₂₃₁ and the negative lens L ₃₃₃ , respectively. The negative lens L ₃₃₃ is made of resin.

The fourth lens group G ₃₄ is configured by arranging a positive lens L ₃₄₁ and a negative lens L _{342 in this} order from the object side. An aspherical surface is formed on the object side surface of the positive lens L ₃₄₁ . The positive lens L ₃₄₁ and the negative lens L ₃₄₂ are cemented.

The fifth lens group G ₃₅ is composed of one negative lens L ₃₅₁ . Aspherical surfaces are formed on both surfaces of the negative lens L ₃₅₁ .

In this zoom lens, the first lens group G ₃₁ , the aperture stop STOP, the third lens group G ₃₃ , and the fifth lens group G ₃₅ are fixed to the image plane IMG, and the second lens group G ₃₂ is used as the optical axis. By moving from the object side to the image plane IMG side along the distance from the wide-angle end to the telephoto end so that the fourth lens group G ₃₄ forms a convex locus along the optical axis toward the object side. By moving it, the image plane position variation due to the magnification change is corrected.

Hereinafter, various numerical data regarding the zoom lens according to the third embodiment will be shown.

(Surface data)
r ₁ =62.179
d ₁ =1.20 nd ₁ =1.92119 νd ₁ =24.0
r ₂ =34.784
d ₂ =7.23 nd ₂ =1.49700 νd ₂ =81.5
r ₃ = -200.911
d ₃ =0.10
r ₄ =30.750
d ₄ =4.50 nd ₃ =1.77250 νd ₃ =49.6
r ₅ = 93.033
d ₅ =D(5) (variable)
r ₆ =128.210
_{d 6 = 0.70 nd 4 = 1.83481} νd 4 = 42.7
r ₇ = 7.011
d ₇ =3.52
r ₈ =-24.714
_{d 8 = 0.50 nd 5 = 1.88100} νd 5 = 40.1
r ₉ =24.714
d ₉ =0.10
r ₁₀ = 14.562
d ₁₀ =2.22 nd ₆ =1.94594 νd ₆ =18.0
r ₁₁ =159.632
d ₁₁ =D(11) (variable)
r ₁₂ =∞ (aperture stop)
d ₁₂ =0.50
r ₁₃ = 11.417 (aspherical surface)
d ₁₃ =4.52 nd ₇ =1.58313 νd ₇ =59.5
r ₁₄ =-26.880 (aspherical surface)
d ₁₄ =0.27
r ₁₅ = -45.585
d ₁₅ =2.60 nd ₈ =1.56732 νd ₈ =42.8
r ₁₆ = 76.550
d ₁₆ =0.51
r ₁₇ =14.780 (aspherical surface)
d ₁₇ =2.72 nd ₉ =1.63980 νd ₉ =23.3
r ₁₈ =7.348 (aspherical surface)
d ₁₈ =D(18) (variable)
r ₁₉ = 10.455 (aspherical surface)
d ₁₉ =4.20 nd ₁₀ =1.49710 νd ₁₀ =81.6
r ₂₀ =-9.446
d ₂₀ =0.60 nd ₁₁ =1.90366 νd ₁₁ =31.3
r ₂₁ =-12.774
d ₂₁ =D(21) (variable)
r ₂₂ =-20.399 (aspherical surface)
_{d 22 = 0.62 nd 12 = 1.58250} νd 12 = 30.2
r ₂₃ = -26.802 (non-spherical)
d ₂₃ =BF
r ₂₄ =∞ (image plane)

Cone coefficient (ε) and aspherical coefficient (A, B, C, D, E)
(Thirteenth surface)
ε=1.0000,
A=0, B=-5.3133×10 ^-5 , C=-8.3180×10 ^-8 ,
D=-2.7430×10 ^-8 , E=9.5883×10 ^-10
(14th surface)
ε=1.0000,
A=0, B=5.4153×10 ^-5 , C=-2.3938×10 ^-6 ,
D=6.5454×10 ^-8 , E=2.2311×10 ^-10
(17th surface)
ε=1.0000,
A=0, B=-1.8540×10 ^-4 , C=-8.8191×10 ^-6 ,
D=3.1507×10 ^-7 , E=-3.3095×10 ^-9
(Eighteenth surface)
ε=1.0000,
A=0, B=-3.7781×10 ^-4 , C=-1.0695×10 ^-5 ,
D=2.5490×10 ^-7 , E=-3.0125×10 ^-9
(19th surface)
ε = 0.3813,
A=0, B=-1.1796×10 ^-4 , C=-4.2792×10 ^-7 ,
D=3.5956×10 ^-9 , E=-1.1661×10 ^-10
(22nd surface)
ε=1.0000,
A=0, B=9.6149×10 ^-4 , C=-5.3689×10 ^-5 ,
D=1.5473×10 ^-6 , E=-5.7574×10 ^-8
(23rd surface)
ε=1.0000,
A=0, B=9.3248×10 ^-4 , C=-4.5265×10 ^-5 ,
D = 3.9520 x 10 ^-7 , E = -2.6234 x 10 ^-8

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 4.78 21.57 97.16
F number 1.63 2.98 4.07
Half angle of view (ω) 34.23 7.90 1.75
D(5) 0.87 20.89 31.01
D(11) 32.23 12.22 2.10
D(18) 7.93 3.70 10.90
D(21) 4.47 8.70 1.50
Back focus (BF) (air conversion length) 5.96 5.99 6.06

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 45.03 0.00
26-7.82 30.14
3 13 26.67 0.00
4 19 14.02 -2.97
5 22 -152.00 0.00

(Numerical value regarding conditional expression (1))
fn (focal length of the negative lens L _333, which is formed of resin) = - 26.65
fp (focal length of positive lens L ₃₁₂ formed of glass material having anomalous dispersion)=60.27
|fn/fp|=0.44

(Numerical value regarding conditional expression (2))
Δθg, F=0.028
Δθg, F: Anomalous dispersion of positive lens L ₃₁₂

(Numerical value regarding conditional expression (3))
β2T (magnification of the second lens group G ₃₂ at the telephoto end) = -1.82
β3T (magnification of the third lens group G ₃₃ at the telephoto end)=-0.89
β2T/β3T=2.05

(Numerical value regarding conditional expression (4))
β3W (magnification of third lens group G ₃₃ at wide-angle end)=−3.46
β4W (magnification of fourth lens group G ₃₄ at wide-angle end)=0.12
β3W/β4W=-29.60

(Numerical value regarding conditional expression (5))
(F4/f3)/(f2/ft)=-6.08

(Numerical value regarding conditional expression (6))
(Dt/dT)p=-7.7×10 ^-6
(Dt / dT) p: an average value of the refractive index change with respect to the d-line per temperature change 1 ℃ in the positive lens L ₃₁₂

(Numerical value regarding conditional expression (7))
(Dt/dT) n=-77.1×10 ^-6
(Dt/dT)n: Average value of change in refractive index with respect to d-line per 1° C. temperature change in the negative lens L ₃₃₃

FIG. 7 is a diagram of various types of aberration of the zoom lens according to the third example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the C line (656.27 nm), and the long broken line is the g line (435. The characteristics of the wavelength corresponding to (83 nm) are shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

FIG. 8 is a sectional view taken along the optical axis to show the configuration of the zoom lens according to the fourth example. The figure shows the wide-angle end state of the optical system. This zoom lens includes, in order from the object side (not shown), a first lens group G ₄₁ having a positive refractive power, a second lens group G ₄₂ having a negative refractive power, and a third lens group having a positive refractive power. G ₄₃ , a fourth lens group G ₄₄ having a positive refractive power, and a fifth lens group G ₄₅ having a negative refractive power are arranged and configured. An aperture stop STOP that defines a predetermined aperture is arranged between the second lens group G ₄₂ and the third lens group G ₄₃ . IMG indicates the image plane.

The first lens group G ₄₁ includes, in order from the object side, a negative lens L ₄₁₁ , a positive lens L _412, and a positive lens L ₄₁₃ . The negative lens L ₄₁₁ and the positive lens L ₄₁₂ are cemented together. The positive lens L ₄₁₂ is made of a glass material having anomalous dispersion. The positive lens L ₄₁₃ may be formed of a glass material having anomalous dispersion instead of the positive lens L ₄₁₂ .

The second lens group G ₄₂ is configured by arranging a negative lens L ₄₂₁ , a negative lens L _422, and a positive lens L _{423 in} order from the object side.

The third lens group G ₄₃ is configured by sequentially arranging a positive lens L ₄₃₁ and a negative lens L ₄₃₂ from the object side. Aspherical surfaces are formed on both surfaces of the positive lens L ₄₃₁ and the negative lens L ₄₃₂ . The negative lens L ₄₃₂ is made of resin.

The fourth lens group G ₄₄ is configured by arranging a positive lens L ₄₄₁ and a negative lens L _{442 in} order from the object side. An aspherical surface is formed on the object side surface of the positive lens L ₄₄₁ . The positive lens L ₄₄₁ and the negative lens L ₄₄₂ are cemented together.

The fifth lens group G ₄₅ is composed of one negative lens L ₄₅₁ . Aspherical surfaces are formed on both surfaces of the negative lens L ₄₅₁ .

In this zoom lens, the first lens group G ₄₁ , the aperture stop STOP, the third lens group G ₄₃ , and the fifth lens group G ₄₅ are fixed to the image plane IMG, and the second lens group G ₄₂ is used as the optical axis. By moving from the object side to the image plane IMG side along the distance from the wide-angle end to the telephoto end so that the fourth lens group G ₄₄ forms a convex locus on the object side along the optical axis. By moving it, the image plane position variation due to the magnification change is corrected.

Hereinafter, various numerical data regarding the zoom lens according to the fourth embodiment will be shown.

(Surface data)
r ₁ =62.419
d ₁ =1.20 nd ₁ =1.92119 νd ₁ =24.0
r ₂ =35.097
d ₂ =8.24 nd ₂ =1.49700 νd ₂ =81.5
r ₃ =-201.717
d ₃ =0.10
r ₄ =30.753
d ₄ =4.65 nd ₃ =1.77250 νd ₃ =49.6
r ₅ = 90.253
d ₅ =D(5) (variable)
r ₆ =103.212
_{d 6 = 0.70 nd 4 = 1.83481} νd 4 = 42.7
r ₇ = 7.039
d ₇ =3.91
r ₈ =-23.945
_{d 8 = 0.50 nd 5 = 1.88100} νd 5 = 40.1
r ₉ =23.945
d ₉ =0.10
r ₁₀ = 14.855
d ₁₀ =2.31 nd ₆ =1.94594 νd ₆ =18.0
r ₁₁ =209.149
d ₁₁ =D(11) (variable)
r ₁₂ =∞ (aperture stop)
d ₁₂ =0.50
r ₁₃ = 11.096 (aspherical surface)
d ₁₃ =3.75 nd ₇ =1.58313 νd ₇ =59.5
r ₁₄ =-36.273 (aspherical surface)
d ₁₄ =0.22
r ₁₅ = 14.987 (aspherical surface)
d ₁₅ =3.04 nd ₈ =1.63980 νd ₈ =23.3
r ₁₆ =6.909 (aspherical surface)
d ₁₆ =D(16) (variable)
r ₁₇ =11.776 (aspherical surface)
d ₁₇ =2.97930 nd ₉ =1.49710 νd ₉ =81.6
r ₁₈ =-10.273
d ₁₈ =0.60000 nd ₁₀ =1.90366 νd ₁₀ =31.3
r ₁₉ =-15.070
d ₁₉ =D(19) (variable)
r ₂₀ =-13.130 (aspherical surface)
d ₂₀ =1.09 nd ₁₁ =1.58 250 νd ₁₁ =30.2
r ₂₁ = -15.887 (aspherical surface)
d ₂₁ =BF
r ₂₂ =∞ (image plane)

Cone coefficient (ε) and aspherical coefficient (A, B, C, D, E)
(Thirteenth surface)
ε=1.0000,
A=0, B=-5.93642×10 ^-5 , C=2.04251×10 ^-7 ,
D=-6.47178×10 ^-8 , E=1.14750×10 ^-9
(14th surface)
ε=1.0000,
A=0, B=6.11171×10 ^-5 , C=-2.70569×10 ^-6 ,
D = 6.87138 x 10 ^-8 , E = -1.675 46 x 10 ^-10
(15th surface)
ε=1.0000,
A=0, B=-1.87001×10 ^-4 , C=-5.17978×10 ^-6 ,
D=2.79733×10 ^-7 , E=-3.46826×10 ^-9
(16th surface)
ε=1.0000,
A=0, B=-4.06713×10 ^-4 , C=-7.50481×10 ^-6 ,
D=4.02649×10 ^-7 , E=-1.03946×10 ^-8
(17th surface)
ε = -0.0659,
A=0, B=-2.13228×10 ^-5 , C=1.43184×10 ^-7 ,
D=3.45741×10 ^-9 , E=3.53705×10 ^-10
(20th surface)
ε=1.0000,
A=0, B=2.26993×10 ^-3 , C=-4.21185×10 ^-5 ,
D=1.47892×10 ^-6 , E=-7.87719×10 ^-8
(21st surface)
ε=1.0000,
A=0, B=2.42234×10 ^-3 , C=-1.68550×10 ^-5 ,
D=4.51419×10 ^-8 , E=-5.42413×10 ^-8

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 4.78 21.00 92.80
F number 1.55 3.04 3.94
Half angle of view (ω) 33.23 7.91 1.79
D(5) 0.87 20.57 31.01
D(11) 32.23 12.53 2.10
D(16) 7.89 3.59 10.29
D(19) 4.23 8.53 1.83
Back focus (BF) (air conversion length) 5.97 5.97 6.06

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 45.43 0.00
2 6 -7.74 30.14
3 13 24.17 0.00
4 17 16.45 -2.40
5 20 -152.01 0.00

(Numerical value regarding conditional expression (1))
fn (focal length of negative lens L ₄₃₂ formed of resin)=-23.48
fp (focal length of positive lens L ₄₁₂ formed of glass material having anomalous dispersion)=60.85
|fn/fp|=0.39

(Numerical value regarding conditional expression (2))
Δθg, F=0.028
Δθg, F: Anomalous dispersion of positive lens L ₄₁₂

(Numerical value regarding conditional expression (3))
β2T (magnification of the second lens group G ₄₂ at the telephoto end)=−6.32
β3T (magnification of third lens group G ₄₃ at telephoto end)=−0.70
β2T/β3T=8.97

(Numerical value regarding conditional expression (4))
β3W (magnification of third lens group G ₄₃ at wide-angle end)=-1.39
β4W (magnification of fourth lens group G ₄₄ at wide-angle end)=0.29
β3W/β4W=-4.83

(Numerical value regarding conditional expression (5))
(F4/f3)/(f2/ft)=-8.16

(Numerical value regarding conditional expression (6))
(Dt/dT)p=-7.7×10 ^-6
(Dt/dT)p: Average value of change in refractive index for d line per 1° C. temperature change in the positive lens L ₄₁₂

(Numerical value regarding conditional expression (7))
(Dt/dT) n=-77.1×10 ^-6
(Dt/dT)n: Average value of change in refractive index with respect to d line per 1° C. temperature change in the negative lens L ₄₃₂ .

FIG. 9 is a diagram of various types of aberration of the zoom lens according to the fourth example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the C line (656.27 nm), and the long broken line is the g line (435. The characteristics of the wavelength corresponding to (83 nm) are shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

FIG. 10 is a sectional view taken along the optical axis showing the configuration of the zoom lens according to the fifth example. The figure shows the wide-angle end state of the optical system. This zoom lens comprises, in order from the object side (not shown), a first lens group G ₅₁ having a positive refractive power, a second lens group G ₅₂ having a negative refractive power, and a third lens group having a positive refractive power. G ₅₃ and a fourth lens group G ₅₄ having a positive refractive power are arranged and configured. An aperture stop STOP that defines a predetermined aperture is arranged between the second lens group G ₅₂ and the third lens group G ₅₃ . IMG indicates the image plane.

The first lens group G ₅₁ includes a negative lens L ₅₁₁ , a positive lens L _512, and a positive lens L ₅₁₃ , which are arranged in this order from the object side. The negative lens L ₅₁₁ and the positive lens L ₅₁₂ are cemented together. The positive lens L ₅₁₂ is made of a glass material having anomalous dispersion. The positive lens L ₅₁₃ may be formed of a glass material having anomalous dispersion, instead of the positive lens L ₅₁₂ .

The second lens group G ₅₂ includes a negative lens L ₅₂₁ , a negative lens L _522, and a positive lens L ₅₂₃ , which are arranged in this order from the object side.

The third lens group G ₅₃ is configured by arranging a positive lens L ₅₃₁ , a negative lens L _532, and a negative lens L _{533 in this} order from the object side. Aspherical surfaces are formed on both surfaces of each of the positive lens L ₅₃₁ and the negative lens L ₅₃₃ . The negative lens L ₅₃₃ is made of resin.

The fourth lens group G ₅₄ is configured by arranging a positive lens L ₅₄₁ and a negative lens L _{542 in this} order from the object side. An aspherical surface is formed on the object side surface of the positive lens L ₅₄₁ . The positive lens L ₅₄₁ and the negative lens L ₅₄₂ are cemented together.

In this zoom lens, while the first lens group G ₅₁ , the aperture stop STOP, and the third lens group G ₅₃ are fixed with respect to the image plane IMG, the second lens group G ₅₂ is imaged from the object side along the optical axis. The magnification is changed from the wide-angle end to the telephoto end by moving it to the surface IMG side, and the fourth lens group G ₅₄ is moved along the optical axis so as to form a convex locus on the object side, thereby changing the magnification. The accompanying image plane position variation is corrected.

Hereinafter, various numerical data regarding the zoom lens according to the fifth example will be shown.

(Surface data)
r ₁ =62.430
d ₁ =1.20 nd ₁ =1.92119 νd ₁ =24.0
r ₂ =35.016
d ₂ =7.64 nd ₂ =1.49700 νd ₂ =81.5
r ₃ = -208.168
d ₃ =0.10
r ₄ =30.928
d ₄ =4.78 nd ₃ =1.77250 νd ₃ =49.6
r ₅ =93.618
d ₅ =D(5) (variable)
r ₆ =129.259
_{d 6 = 0.70 nd 4 = 1.83481} νd 4 = 42.7
r ₇ =6.943
d ₇ =3.56
r ₈ =-23.543
_{d 8 = 0.50 nd 5 = 1.88100} νd 5 = 40.1
r ₉ =23.543
d ₉ =0.10
r ₁₀ =14.473
d ₁₀ =2.29 nd ₆ =1.94594 νd ₆ =18.0
r ₁₁ =397.728
d ₁₁ =D(11) (variable)
r ₁₂ =∞ (aperture stop)
d ₁₂ =0.50
r ₁₃ =12.185 (aspherical surface)
d ₁₃ =4.13 nd ₇ =1.58313 νd ₇ =59.5
r ₁₄ =-16.726 (aspherical surface)
d ₁₄ =0.20
r ₁₅ =-16.980
d ₁₅ =0.50 nd ₈ =1.56732 νd ₈ =42.8
r ₁₆ = -61.449
d ₁₆ =2.61
r ₁₇ =17.601 (aspherical surface)
d ₁₇ =2.28 nd ₉ =1.63980 νd ₉ =23.3
r ₁₈ =7.858 (aspherical surface)
d ₁₈ =D(18) (variable)
r ₁₉ = 10.435 (aspherical surface)
d ₁₉ =4.20 nd ₁₀ =1.49710 νd ₁₀ =81.6
r ₂₀ =-10.896
d ₂₀ =0.60 nd ₁₁ =1.90366 νd ₁₁ =31.3
r ₂₁ =-15.155
d ₂₁ =BF
r ₂₂ =∞ (image plane)

Cone coefficient (ε) and aspherical coefficient (A, B, C, D, E)
(Thirteenth surface)
ε=1.0000,
A = 0, B = -9.81167 x 10 ^-5 , C = 1.36111 x 10 ^-6 ,
D=2.65151×10 ^-8 , E=-2.39252×10 ^-10
(14th surface)
ε=1.0000,
A=0, B=-5.15992×10 ^-5 , C=7.59145×10 ^-6 ,
D=-1.11528×10 ^-7 , E=4.38240×10 ^-10
(17th surface)
ε=1.0000,
A=0, B=-2.71925×10 ⁻⁴ , C=2.05464×10 ⁻⁵ ,
D=-4.94101×10 ^-7 , E=1.30947×10 ^-9
(Eighteenth surface)
ε=1.0000,
A=0, B=-3.89055×10 ^-4 , C=2.09885×10 ^-5 ,
D=-5.97395×10 ^-7 , E=-5.34582×10 ^-10
(19th surface)
ε = 2.1868,
A=0, B=-2.70892×10 ^-4 , C=-3.11191×10 ^-6 ,
D=4.29915×10 ^-8 , E=-2.38122×10 ^-9

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 4.78 21.57 97.16
F number 1.63 2.88 4.11
Half angle of view (ω) 34.20 7.95 1.74
D(5) 0.87 21.24 31.01
D(11) 32.23 11.87 2.10
D(18) 9.95 5.38 12.94
Back focus (BF) (air conversion length) 10.61 15.22 7.75

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 45.31 0.00
26-7.82 30.14
3 13 28.16 0.00
4 19 15.00 -2.99

(Numerical value regarding conditional expression (1))
fn (focal length of negative lens L ₅₃₃ formed of resin)=-24.41
fp (focal length of positive lens L ₅₁₂ formed of glass material having anomalous dispersion)=60.95
│fn/fp│=0.40

(Numerical value regarding conditional expression (2))
Δθg, F=0.028
Δθg, F: Anomalous dispersion of positive lens L ₅₁₂

(Numerical value regarding conditional expression (3))
β2T (magnification of the second lens group G ₅₂ at the telephoto end)=−6.64
β3T (magnification of the third lens group G ₅₃ at the telephoto end) = -0.94
β2T/β3T=7.09

(Numerical value regarding conditional expression (4))
β3W (magnification of third lens group G ₅₃ at wide-angle end)=−2.74
β4W (magnification of fourth lens group G ₅₄ at wide-angle end)=0.15
β3W/β4W=-17.81

(Numerical value regarding conditional expression (5))
(F4/f3)/(f2/ft)=-6.62

(Numerical value regarding conditional expression (6))
(Dt/dT)p=-7.7×10 ^-6
(Dt/dT)p: Average value of change in refractive index for d line per 1° C. temperature change in positive lens L ₅₁₂

(Numerical value regarding conditional expression (7))
(Dt/dT) n=-77.1×10 ^-6
(Dt/dT)n: Average value of change in refractive index with respect to d line per 1° C. temperature change in the negative lens L ₅₃₃

FIG. 11 is a diagram of various types of aberration of the zoom lens according to the fifth example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the C line (656.27 nm), and the long broken line is the g line (435. The characteristics of the wavelength corresponding to (83 nm) are shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

FIG. 12 is a sectional view taken along the optical axis showing the configuration of the zoom lens according to the sixth example. The figure shows the wide-angle end state of the optical system. This zoom lens includes, in order from the object side (not shown), a first lens group G ₆₁ having a positive refractive power, a second lens group G ₆₂ having a negative refractive power, and a third lens group having a positive refractive power. G ₆₃ , a fourth lens group G ₆₄ having a positive refractive power, and a fifth lens group G ₆₅ having a negative refractive power are arranged and configured. An aperture stop STOP that defines a predetermined aperture is arranged between the second lens group G ₆₂ and the third lens group G ₆₃ . IMG indicates the image plane.

The first lens group G ₆₁ includes a negative lens L ₆₁₁ , a positive lens L _612, and a positive lens L ₆₁₃ , which are arranged in this order from the object side. The negative lens L ₆₁₁ and the positive lens L ₆₁₂ are cemented together. The positive lens L ₆₁₂ is made of a glass material having anomalous dispersion. The positive lens L ₆₁₃ , instead of the positive lens L ₆₁₂ , may be made of a glass material having anomalous dispersion.

The second lens group G ₆₂ includes, in order from the object side, a negative lens L ₆₂₁ , a negative lens L _622, and a positive lens L ₆₂₃ .

The third lens group G ₆₃ is configured by arranging a positive lens L ₆₃₁ and a negative lens L _{632 in this} order from the object side. Aspherical surfaces are formed on both surfaces of the positive lens L ₆₃₁ and the negative lens L ₆₃₂ . The negative lens L ₆₃₂ is made of resin.

The fourth lens group G ₆₄ is composed of a positive lens L ₆₄₁ and a negative lens L ₆₄₂ arranged in order from the object side. An aspherical surface is formed on the object side surface of the positive lens L ₆₄₁ . The positive lens L ₆₄₁ and the negative lens L ₆₄₂ are cemented together.

The fifth lens group G ₆₅ is composed of one negative lens L ₆₅₁ . Aspherical surfaces are formed on both surfaces of the negative lens L ₆₅₁ .

In this zoom lens, the first lens group G ₆₁ , the aperture stop STOP, the third lens group G ₆₃ , and the fifth lens group G ₆₅ are fixed to the image plane IMG, and the second lens group G ₆₂ is used as the optical axis. By moving from the object side to the image plane IMG side along the distance from the wide-angle end to the telephoto end so that the fourth lens group G ₆₄ forms a convex locus on the object side along the optical axis. By moving it, the image plane position variation due to the magnification change is corrected.

Hereinafter, various numerical data regarding the zoom lens according to the sixth embodiment will be shown.

(Surface data)
r ₁ =56.481
d ₁ =1.20 nd ₁ =1.92119 νd ₁ =24.0
r ₂ =33.513
d ₂ =7.55 nd ₂ =1.43875 νd ₂ =94.9
r ₃ =-166.397
d ₃ =0.10
r ₄ =30.238
d ₄ =4.44 nd ₃ =1.77250 νd ₃ =49.6
r ₅ =96.482
d ₅ =D(5) (variable)
r ₆ = 93.325
_{d 6 = 0.70 nd 4 = 1.83481} νd 4 = 42.7
r ₇ =6.857
d ₇ =3.49
r ₈ =-25.049
_{d 8 = 0.50 nd 5 = 1.88100} νd 5 = 40.1
r ₉ =25.049
d ₉ =0.10
r ₁₀ =14.263
d ₁₀ =2.25 nd ₆ =1.94594 νd ₆ =18.0
r ₁₁ =124.425
d ₁₁ =D(11) (variable)
r ₁₂ =∞ (aperture stop)
d ₁₂ =0.50
r ₁₃ = 11.807 (aspherical surface)
d ₁₃ =4.63 nd ₇ =1.58313 νd ₇ =59.5
r ₁₄ =-80.888 (aspherical surface)
d ₁₄ =1.37
r ₁₅ = 19.636 (aspherical surface)
d ₁₅ =4.29 nd ₈ =1.63980 νd ₈ =23.3
r ₁₆ =7.726 (aspherical surface)
d ₁₆ =D(16) (variable)
r ₁₇ = 10.018 (aspherical surface)
d ₁₇ =4.02 nd ₉ =1.49710 νd ₉ =81.6
r ₁₈ =-9.573
d ₁₈ =0.60 nd ₁₀ =1.90366 νd ₁₀ =31.3
r ₁₉ =-12.587
d ₁₉ =D(19) (variable)
r ₂₀ =-11.645 (aspherical surface)
d ₂₀ =0.95 nd ₁₁ =1.58 250 νd ₁₁ =30.2
r ₂₁ =-13.910 (aspherical surface)
d ₂₁ =BF
r ₂₂ =∞ (image plane)

Cone coefficient (ε) and aspherical coefficient (A, B, C, D, E)
(Thirteenth surface)
ε=1.0000,
A=0, B=-3.02604×10 ⁻⁵ , C=−5.21717×10 ⁻⁷ ,
D=3.03622×10 ^-8 , E=-9.48195×10 ^-11
(14th surface)
ε=1.0000,
A=0, B=-3.38412×10 ^-7 , C=-9.28499×10 ^-7 ,
D=6.73936×10 ^-8 , E=-5.50806×10 ^-10
(15th surface)
ε=1.0000,
A=0, B=-1.61662×10 ^-4 , C=-2.85697×10 ^-6 ,
D=1.30593×10 ^-8 , E=1.79297×10 ^-10
(16th surface)
ε=1.0000,
A=0, B=-2.54097×10 ^-4 , C=-3.60998×10 ^-6 ,
D = -3.376 24 x 10 ^-7 , E = 1.01019 x 10 ^-8
(17th surface)
ε = 0.6794,
A=0, B=-1.64256×10 ^-4 , C=-3.96041×10 ^-7 ,
D = -5.59713 x 10 ^-8 , E = 1.21454 x 10 ^-9
(20th surface)
ε=1.0000,
A=0, B=2.37777×10 ^-3 , C=-1.45455×10 ^-4 ,
D=1.06482×10 ^-5 , E=-3.46813×10 ^-7
(21st surface)
ε=1.0000,
A=0, B=2.56306×10 ^-3 , C=-1.59678×10 ^-4 ,
D=1.23918×10 ^-5 , E=-4.32288×10 ^-7

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 4.78 21.57 102.00
F number 1.65 2.93 4.16
Half angle of view (ω) 33.64 7.81 1.64
D(5) 0.77 20.70 30.89
D(11) 31.71 11.79 1.60
D(16) 8.05 3.99 11.68
D(19) 4.83 8.89 1.20
Back focus (BF) (air conversion length) 5.53 5.54 5.64

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 44.64 0.00
2 6 -7.86 30.12
3 13 29.45 0.00
4 17 13.38 -3.63
5 20 -145.25 0.00

(Numerical value regarding conditional expression (1))
fn (focal length of negative lens L _{632 made} of resin)=-23.17
fp (focal length of positive lens L ₆₁₂ formed of a glass material having anomalous dispersion)=64.32
|fn/fp|=0.36

(Numerical value regarding conditional expression (2))
Δθg, F=0.046
Δθg,F: Anomalous dispersion of positive lens L ₆₁₂

(Numerical value regarding conditional expression (3))
β2T (magnification of second lens group G ₆₂ at telephoto end) = -8.42
β3T (magnification of third lens group G ₆₃ at telephoto end)=−0.73
β2T/β3T=11.49

(Numerical value regarding conditional expression (4))
β3W (magnification of third lens group G ₆₃ at wide angle end)=−4.78
β4W (magnification of the fourth lens group G ₆₄ at the wide-angle end)=0.08
β3W/β4W=-57.79

(Numerical value regarding conditional expression (5))
(F4/f3)/(f2/ft)=-5.90

(Numerical value regarding conditional expression (6))
(Dt/dT)p=-7.9×10 ^-6
(Dt/dT)p: average value of change in refractive index with respect to d line per 1° C. temperature change in the positive lens L ₆₁₂

(Numerical value regarding conditional expression (7))
(Dt/dT) n=-77.1×10 ^-6
(Dt/dT)n: Average value of change in refractive index with respect to d line per 1° C. temperature change in the negative lens _L632

FIG. 13 is a diagram of various types of aberration of the zoom lens according to the sixth example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the C line (656.27 nm), and the long broken line is the g line (435. The characteristics of the wavelength corresponding to (83 nm) are shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

FIG. 14 is a sectional view taken along the optical axis to show the configuration of the zoom lens according to the seventh example. The figure shows the wide-angle end state of the optical system. This zoom lens comprises, in order from the object side, not shown, a first lens group G ₇₁ having a positive refractive power, a second lens group G ₇₂ having a negative refractive power, and a third lens group having a positive refractive power. G ₇₃ , a fourth lens group G ₇₄ having a positive refractive power, and a fifth lens group G ₇₅ having a positive refractive power are arranged. An aperture stop STOP that defines a predetermined aperture is arranged between the second lens group G ₇₂ and the third lens group G ₇₃ . IMG indicates the image plane.

The first lens group G ₇₁ is configured by arranging a negative lens L ₇₁₁ , a positive lens L _712, and a positive lens L _{713 in} order from the object side. The negative lens L ₇₁₁ and the positive lens L ₇₁₂ are arranged close to each other. The positive lens L ₇₁₂ is made of a glass material having anomalous dispersion. The positive lens L ₇₁₃ may be formed of a glass material having anomalous dispersion, instead of the positive lens L ₇₁₂ .

The second lens group G ₇₂ is configured by arranging a negative lens L ₇₂₁ , a negative lens L _722, and a positive lens L _{723 in} order from the object side.

The third lens group G ₇₃ is configured by arranging a positive lens L ₇₃₁ and a negative lens L _{732 in this} order from the object side. Aspherical surfaces are formed on both sides of each of the positive lens L ₇₃₁ and the negative lens L ₇₃₂ . The negative lens L ₇₃₂ is made of resin.

The fourth lens group G ₇₄ is configured by arranging a positive lens L ₇₄₁ and a negative lens L _{742 in} order from the object side. An aspherical surface is formed on the object side surface of the positive lens L ₇₄₁ . The positive lens L ₇₄₁ and the negative lens L ₇₄₂ are cemented.

The fifth lens group G ₇₅ is composed of one positive lens L ₇₅₁ . Aspherical surfaces are formed on both surfaces of the positive lens L ₇₅₁ .

In this zoom lens, the first lens group G ₇₁ , the aperture stop STOP, the third lens group G ₇₃ , and the fifth lens group G ₇₅ are fixed to the image plane IMG, and the second lens group G ₇₂ is used as the optical axis. By moving from the object side to the image plane IMG side along the distance from the wide-angle end to the telephoto end so that the fourth lens group G ₇₄ forms a convex locus on the object side along the optical axis. By moving it, the image plane position variation due to the magnification change is corrected.

Hereinafter, various numerical data relating to the zoom lens according to the example 7 will be shown.

(Surface data)
r ₁ =54.003
d ₁ =1.20 nd ₁ =1.92119 νd ₁ =24.0
r ₂ =32.260
d ₂ =0.38
r ₃ =32.276
d ₃ =7.47 nd ₂ =1.49700 νd ₂ =81.5
r ₄ = -351.840
d ₄ =0.10
r ₅ =31.942
d ₅ =4.61 nd ₃ =1.77250 νd ₃ =49.6
r ₆ = 98.728
d ₆ =D(6) (variable)
r ₇ = 45.833
d ₇ =0.70 nd ₄ =1.83481 νd ₄ =42.7
r ₈ =6.431
d ₈ =3.73
r ₉ =-24.117
_{d 9 = 0.50 nd 5 = 1.88100} νd 5 = 40.1
r ₁₀ =24.117
d ₁₀ =0.10
r ₁₁ = 13.677
d ₁₁ = 2.19 nd ₆ = 1.94594 νd ₆ =18.0
r ₁₂ =99.888
d ₁₂ =D(12) (variable)
r ₁₃ =∞ (aperture stop)
d ₁₃ =0.50
r ₁₄ =12.022 (aspherical surface)
d ₁₄ =3.64 nd ₇ =1.58313 νd ₇ =59.5
r ₁₅ = -29.324 (aspherical surface)
d ₁₅ =1.00
r ₁₆ =15.680 (aspherical surface)
d ₁₆ =2.89 nd ₈ =1.63980 νd ₈ =23.3
r ₁₇ =7.047 (aspherical surface)
d ₁₇ =D(17) (variable)
r ₁₈ =12.960 (aspherical surface)
d ₁₈ =3.02 nd ₉ =1.49710 νd ₉ =81.6
r ₁₉ =-9.367
d ₁₉ =0.60 nd ₁₀ =1.90366 νd ₁₀ =31.3
r ₂₀ =-13.474
d ₂₀ =D(20) (variable)
r ₂₁ =-12.078 (aspherical surface)
d ₂₁ =1.07 nd ₁₁ =1.58 250 νd ₁₁ =30.2
r ₂₂ =-12.219 (aspherical surface)
d ₂₂ =BF
r ₂₃ =∞ (image plane)

Cone coefficient (ε) and aspherical coefficient (A, B, C, D, E)
(14th surface)
ε=1.0000,
A=0, B=-6.32431×10 ^-5 , C=3.43592×10 ^-7 ,
D = -5.21405 x 10 ^-8 , E = 1.12665 x 10 ^-9
(15th surface)
ε=1.0000,
A=0, B=5.93565×10 ^-5 , C=-2.64176×10 ^-6 ,
D = 6.40413 x 10 ^-8 , E = 1.34951 x 10 ^-11
(16th surface)
ε=1.0000,
A=0, B=-2.30393×10 ^-4 , C=-6.78401×10 ^-6 ,
D=2.92316×10 ^-7 , E=-3.32360×10 ^-9
(17th surface)
ε=1.0000,
A=0, B=-4.95824×10 ^-4 , C=-8.25739×10 ^-6 ,
D=2.20262×10 ^-7 , E=-4.43098×10 ^-9
(Eighteenth surface)
ε = -0.0051,
A=0, B=-1.85684×10 ^-5 , C=-6.18413×10 ^-7 ,
D = -9.81420 x 10 ^-9 , E = 9.30689 x 10 ^-10
(21st surface)
ε=1.0000,
A=0, B=1.34460×10 ^-3 , C=-1.92059×10 ^-5 ,
D=1.25016×10 ^-6 , E=-7.06681×10 ^-8
(22nd surface)
ε=1.0000,
A = 0, B = 1.46781 x 10 ^-3 , C = -1.58258 x 10 ^-5 ,
D=1.17078×10 ^-6 , E=-7.57132×10 ^-8

(Various data)
Wide-angle end Intermediate focal position Telephoto end focal length 4.78 21.00 92.80
F number 1.53 3.00 3.94
Half angle of view (ω) 32.52 7.93 1.80
D(6) 0.87 20.57 31.01
D(12) 32.23 12.54 2.10
D(17) 7.94 3.40 10.59
D(20) 4.34 8.88 1.68
Back focus (BF) (air conversion length) 5.98 6.00 6.04

(Zoom lens group data)
Group Start surface Focal length Lens movement amount (+ on image plane IMG side)
1 1 45.49 0.00
27-7.79 30.14
3 14 24.35 0.00
4 18 16.60 -2.65
5 21 1000.04 0.00

(Numerical value regarding conditional expression (1))
fn (focal length of negative lens L ₇₃₂ formed of resin)=-23.02
fp (focal length of positive lens L ₇₁₂ formed of glass material having anomalous dispersion)=59.87
|fn/fp|=0.38

(Numerical value regarding conditional expression (2))
Δθg, F=0.028
Δθg, F: Anomalous dispersion of positive lens L ₇₁₂

(Numerical value regarding conditional expression (3))
β2T (magnification of the second lens group G ₇₂ at the telephoto end)=-6.39
β3T (magnification of third lens group G ₇₃ at telephoto end)=−0.71
β2T/β3T = 9.04

(Numerical value regarding conditional expression (4))
β3W (magnification of third lens group G ₇₃ at wide-angle end)=-1.46
β4W (magnification of fourth lens group G ₇₄ at wide-angle end)=0.28
β3W/β4W = -5.15

(Numerical value regarding conditional expression (5))
(F4/f3)/(f2/ft)=-8.13

(Numerical value regarding conditional expression (6))
(Dt/dT)p=-7.7×10 ^-6
(Dt/dT)p: Average value of change in refractive index with respect to d line per 1° C. temperature change in the positive lens L ₇₁₂

(Numerical value regarding conditional expression (7))
(Dt/dT) n=-77.1×10 ^-6
(Dt/dT)n: Average value of change in refractive index with respect to d-line per 1° C. temperature change in the negative lens _L732

FIG. 15 is a diagram of various types of aberration of the zoom lens according to the seventh example. In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (587.56 nm), the short broken line is the C line (656.27 nm), and the long broken line is the g line (435. The characteristics of the wavelength corresponding to (83 nm) are shown. In the astigmatism diagram, the vertical axis represents the half angle of view (indicated by ω in the figure), and shows the characteristic of the wavelength corresponding to the d line. In the astigmatism diagram, the solid line represents the sagittal plane (indicated by S in the figure) and the broken line represents the meridional plane (indicated by M in the figure). In the distortion diagram, the vertical axis represents the half angle of view (indicated by ω in the figure) and shows the characteristic of the wavelength corresponding to the d line.

In the numerical data in each of the above-mentioned embodiments, r ₁ , r ₂ ,... Are radii of curvature of the lens surface and the like, d ₁ , d ₂ ,. The intervals, nd ₁ , nd ₂ ,... Show the refractive index for the d line of the lens (587.56 nm), and vd ₁ , vd ₂ ,... Show the Abbe number for the d line of the lens. The unit of length is “mm” and the unit of angle is “°”.

In each of the aspherical shapes, the height in the direction perpendicular to the optical axis is H, the amount of displacement in the optical axis direction at the height H when the lens surface apex is the origin is X(H), and the paraxial radius of curvature is Where R is the conic coefficient, ε is the second-order, fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients, and A, B, C, D, and E are respectively, and when the traveling direction of light is positive, It is represented by the formula shown in.

As shown in each of the above embodiments, according to the present invention, by satisfying each of the above conditional expressions, it is possible to obtain a focus position change even if a sudden change in the environmental temperature occurs even though the structure is simple and compact. It is possible to realize a zoom lens capable of suppressing the above-mentioned problem and ensuring good optical performance. Further, by appropriately disposing a cemented lens or a lens having an aspherical surface, the aberration correction capability can be further improved.

A zoom lens having such characteristics is suitable not only for a small image pickup device installed in a narrow space but also for a surveillance camera, a security camera, etc. which are often installed outdoors where the temperature changes greatly. It is most suitable for imaging devices.

<Application example>
Next, an example in which the zoom lens according to the present invention is applied to an image pickup apparatus will be shown. FIG. 16 is a diagram showing an example of an image pickup apparatus including a zoom lens according to the present invention. As shown in FIG. 16, the image pickup apparatus 100 includes a zoom lens 10, a lens barrel 11, and a solid-state image pickup element 101. The zoom lens 10 is housed in the lens barrel 11, and a drive mechanism (not shown) drives the zoom lens 10 to perform zooming and correction of image plane position variation due to zooming. Although FIG. 16 shows the zoom lens 10 according to the seventh embodiment (see FIG. 14), the zoom lenses according to the first to sixth embodiments can be similarly mounted on the image pickup apparatus 100.

In the image pickup apparatus 100 including the zoom lens 10 and the solid-state image pickup element 101, the image plane IMG shown in FIG. 14 corresponds to the image pickup surface of the solid-state image pickup element 101. As the solid-state imaging device 101, for example, a photoelectric conversion device such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) sensor can be used.

In the imaging device 100, the light incident from the object side of the zoom lens 10 finally forms an image on the imaging surface of the solid-state imaging device 101. Then, the solid-state imaging device 101 photoelectrically converts the received light and outputs it as an electric signal. This output signal is arithmetically processed by a signal processing circuit (not shown) to generate a digital image corresponding to the object image. The digital image can be recorded in a recording medium such as an HDD (Hard Disk Device), a memory card, an optical disk, or a magnetic tape.

With the above configuration, it is possible to realize a small-sized and high-performance imaging device that can obtain a good image even when the environmental temperature changes.

INDUSTRIAL APPLICABILITY As described above, the zoom lens according to the present invention is useful for a small-sized image pickup device equipped with a solid-state image pickup device such as a CCD or a CMOS, and particularly suitable for an image pickup device installed outdoors where the temperature changes greatly. ing.

G ₁₁ , G ₂₁ , G ₃₁ , G ₄₁ , G ₅₁ , G ₆₁ , G ₇₁ First lens group G ₁₂ , G ₂₂ , G ₃₂ , G ₄₂ , G ₅₂ , G ₆₂ , G ₇₂ Second lens group G ₁₃ , G ₂₃ , G ₃₃ , G ₄₃ , G ₅₃ , G ₆₃ , G ₇₃ 3rd lens group G ₁₄ , G ₂₄ , G ₃₄ , G ₄₄ , G ₅₄ , G ₆₄ , G ₇₄ 4th lens group G ₁₅ , G ₂₅ , G ₃₅ , G ₄₅ , G ₆₅ , G ₇₅ Fifth lens group L ₁₁₁ , L ₁₂₁ , L ₁₂₂ , L ₁₃₂ , L ₁₄₂ , L ₁₅₁ , L ₂₁₁ , L ₂₂₁ , L ₂₂₂ , L ₂₃₂ , L ₂₄₂ , L ₂₅₂ , L ₃₁₁ , L ₃₂₁ , L ₃₂₂ , L ₃₃₂ , L ₃₃₃ , L ₃₄₂ , L ₃₅₁ , L ₄₁₁ , L ₄₂₁ , L ₄₂₂ , L ₄₃₂ , L ₄₄₂ , L ₄₅₁ , L ₅₁₁ , L ₅₂₁ , L ₅₂₂ , L ₅₃₂ , L ₅₃₃ , L ₅₄₂ , L ₆₁₁ , L ₆₂₁ , L ₆₂₂ , L ₆₃₂ , L ₆₄₂ , L ₆₅₁ , L ₇₁₁ , L ₇₂₁ , L ₇₂₂ , L ₇₃₂ , L ₇₄₂ negative lens L ₁₁₂ , L ₁₁₃ , L ₁₂₃ , L ₁₃₁ , L ₁₄₁ , L ₂₁₂ , L ₂₁₃ , L ₂₂₃ , L ₂₃₁ , L ₂₄₁ , L ₂₅₁ , L ₃₁₂ , L ₃₁₃ , L ₃₂₃ , L ₃₃₁ , L ₃₄₁ , L ₄₁₂ , L ₄₁₃ , L _423. , L ₄₃₁ , L ₄₄₁ , L ₅₁₂ , L ₅₁₃ , L ₅₂₃ , L ₅₃₁ , L ₅₄₁ , L ₆₁₂ , L ₆₁₃ , L ₆₂₃ , L ₆₃₁ , L ₆₄₁ , L ₇₁₂ , L ₇₁₃ , L ₇₂₃ , L ₇₃₁ , L. ₇₄₁ , L ₇₅₁ Positive lens STOP Aperture stop IMG Image plane 10 Zoom lens 11 Lens barrel 100 Imaging device 101 Solid-state imaging device

Claims (4)

A first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power, and a positive refracting power, which are arranged in order from the object side. A fourth lens group,
In a zoom lens that moves the second lens group along the optical axis to change the distance on the optical axis of each lens group to perform zooming from the wide-angle end to the telephoto end,
The first lens group includes at least one positive lens formed of a glass material having anomalous dispersion,
The third lens group includes at least one negative lens made of resin,
A zoom lens characterized by satisfying the following conditional expression.
(1) 0<|fn/fp|≦0.5
(2)'0.02<Δθg,F<0.06
(3) 2.0≦β2T/β3T≦15.0
(5) -10.0<(f4/f3)/(f2/ft)≤-5.0
However, fn is a focal length of at least one negative lens formed of resin included in the third lens group, and fp is at least formed of a glass material having anomalous dispersion included in the first lens group. The focal length of one positive lens is shown. Δθg,F represents the anomalous dispersion of at least one positive lens formed of a glass material having anomalous dispersion contained in the first lens group. For the anomalous dispersion Δθg,F, the vertical axis is the partial dispersion ratio θg,F, and the horizontal axis is the Abbe's number νd for the d-line, and the coordinates of C7 (νd=60.49, θg,F= 0.5436) and the coordinates of F2 (νd=36.26, θg, F=0.5828) when the standard line is the point on the standard line corresponding to νd of each glass material and that glass material. It is the deviation from θg and F. Further, the partial dispersion ratios θg, F are defined by θg, F=(ng-nF)/(nF-nC), and ng, nF, and nC represent the refractive indices for the g-line, the F-line, and the C-line, respectively. β2T is the magnification of the second lens group at the telephoto end, and β3T is the magnification of the third lens group at the telephoto end. f4 is the focal length of the fourth lens group, f3 is the focal length of the third lens group, f2 is the focal length of the second lens group, and ft is the focal length of the entire optical system at the telephoto end. A first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power, and a positive refracting power, which are arranged in order from the object side. A fourth lens group,
In a zoom lens that moves the second lens group along the optical axis to change the distance on the optical axis of each lens group to perform zooming from the wide-angle end to the telephoto end,
The first lens group includes at least one positive lens formed of a glass material having anomalous dispersion,
The third lens group includes at least one negative lens made of resin ,
By moving the fourth lens group along the optical axis, the fluctuation of the image plane position due to the zooming is corrected,
A zoom lens characterized by satisfying the following conditional expression.
(1) 0<|fn/fp|≦0.5
(2) 0<Δθg, F<0.06
(3) 2.0≦β2T/β3T≦15.0
(4) −70.0≦β3W/β4W≦−7.0
(5) -10.0<(f4/f3)/(f2/ft)≤-5.0
However, fn is a focal length of at least one negative lens formed of resin included in the third lens group, and fp is at least formed of a glass material having anomalous dispersion included in the first lens group. The focal length of one positive lens is shown. Δθg,F represents the anomalous dispersion of at least one positive lens formed of a glass material having anomalous dispersion contained in the first lens group. For the anomalous dispersion Δθg,F, the vertical axis is the partial dispersion ratio θg,F and the horizontal axis is the Abbe number νd for the d-line, and the coordinates of C7 (νd=60.49, θg,F= 0.5436) and the coordinates of F2 (νd=36.26, θg, F=0.5828) when the standard line is the point on the standard line corresponding to νd of each glass material and that glass material. It is the deviation from θg and F. Further, the partial dispersion ratios θg, F are defined by θg, F=(ng-nF)/(nF-nC), and ng, nF, and nC represent the refractive indices for the g-line, the F-line, and the C-line, respectively. β2T is the magnification of the second lens group at the telephoto end, and β3T is the magnification of the third lens group at the telephoto end. β3W represents the magnification of the third lens group at the wide-angle end, and β4W represents the magnification of the fourth lens group at the wide-angle end. f4 is the focal length of the fourth lens group, f3 is the focal length of the third lens group, f2 is the focal length of the second lens group, and ft is the focal length of the entire optical system at the telephoto end. A first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power, and a positive refracting power, which are arranged in order from the object side. A fourth lens group,
In a zoom lens that moves the second lens group along the optical axis to change the distance between the lens groups on the optical axis to perform zooming from the wide-angle end to the telephoto end,
The first lens group includes at least one positive lens formed of a glass material having anomalous dispersion,
The third lens group includes at least one negative lens made of resin,
A zoom lens characterized by satisfying the following conditional expression.
(1)′ 0<|fn/fp|≦0.44
(2) 0<Δθg, F<0.06
(3) 2.0≦β2T/β3T≦15.0
(5) -10.0<(f4/f3)/(f2/ft)≤-5.0
However, fn is a focal length of at least one negative lens formed of resin included in the third lens group, and fp is at least formed of a glass material having anomalous dispersion included in the first lens group. The focal length of one positive lens is shown. Δθg,F represents the anomalous dispersion of at least one positive lens formed of a glass material having anomalous dispersion contained in the first lens group. For the anomalous dispersion Δθg,F, the vertical axis is the partial dispersion ratio θg,F, and the horizontal axis is the Abbe number νd for the d-line, and the coordinates of C7 (νd=60.49, θg,F=the reference glass material). 0.5436) and the coordinates of F2 (νd=36.26, θg, F=0.5828) as the standard line, the point on the standard line corresponding to νd of each glass material and that glass material It is the deviation from θg and F. Further, the partial dispersion ratios θg, F are defined by θg, F=(ng-nF)/(nF-nC), and ng, nF, and nC represent the refractive indices for the g-line, the F-line, and the C-line, respectively. β2T is the magnification of the second lens group at the telephoto end, and β3T is the magnification of the third lens group at the telephoto end. f4 is the focal length of the fourth lens group, f3 is the focal length of the third lens group, f2 is the focal length of the second lens group, and ft is the focal length of the entire optical system at the telephoto end. An image pickup apparatus comprising: the zoom lens according to any one of claims 1 to 3; and a solid-state image pickup element that converts an optical image formed by the zoom lens into an electrical signal.

Images