JP2001228395A - Rear focus type zoom lens and optical equipment using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rear focus type zoom lens provided with excellent performance all over the zoom area and all over the object distance and having a high variable power ratio, and optical equipment using the same. SOLUTION: This zoom lens is provided wit four lens groups, that is, a 1st group having positive refractive power, a 2nd group having negative refractive power, a 3rd group provided with a diaphragm and having positive refractive power and a 4th group having positive refractive power in order from an object side. In the case of variable power from a wide-angle end to a telephoto end, the 2nd group is moved to an image surface side and also the 4th group is moved so as to hold a locus projected to the object side, and focusing is performed by moving the 4th group. The 2nd group is constituted of a 21st negative meniscus lens whose convex surface faces to the object side, a 22nd negative lens whose both lens surfaces are concave and a combined lens obtained by bonding a 23rd positive lens whose both lens surfaces are convex and a 24th negative lens in order from the object side, and the 3rd group is constituted of one positive lens having an aspherical surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear focus type zoom lens and an optical apparatus using the same, and more particularly to a rear focus type zoom lens having a high zoom ratio suitably used for a video camera, a film camera, a broadcast camera, and the like. The present invention relates to a rear focus type zoom lens having a large aperture ratio and a relatively small number of constituent lenses, and an optical apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, a zoom lens used for an optical apparatus such as a video camera or a photographic camera employs a so-called rear focus type in which a lens group other than a first lens group on the object side is moved to perform focusing. Various proposals have been made. In general, a rear focus type zoom lens has a feature that a relatively small and lightweight lens group is moved to perform focusing, so that the driving force of the focus lens group is small, and quick focusing is possible.

[0003] For example, JP-A-62-24233,
JP-A-2-48621 and JP-A-4-433
In Japanese Patent Publication No. 11 and the like, the first positive refractive power in
The first and third lenses include four lens groups, a lens group, a second lens group having a negative refractive power for zooming, a third lens group having a positive refractive power, and a positive fourth lens group. Each lens group of the group is fixed, the second lens group is moved along the optical axis to perform zooming, and the fourth lens group is moved along the optical axis so as to correct the image plane position variation accompanying zooming. A rear focus zoom lens has been proposed which moves the fourth lens group along and moves the fourth lens group for focusing.

In Japanese Patent Application Laid-Open No. 63-29718,
The first lens unit has a positive refractive power and a negative lens, a negative lens, and a positive lens in order from the object side. A second group that controls the first group and a third group that has a positive refractive power and includes an aspheric surface.
A fourth lens unit having a positive refracting power with a slightly large air gap between the lens unit and the image surface to correct for image plane fluctuation due to zooming, and moving for focusing.
A zoom lens composed of a group is disclosed.

In Japanese Patent Application Laid-Open No. 5-72472, a first lens unit having a positive refractive power and a second lens unit for zooming with a negative refractive power are arranged in order from the object side. A zoom lens using an aspheric surface having a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power that moves on the optical axis to maintain the image plane position is disclosed. The second group includes a meniscus negative lens, a biconcave lens, and a positive lens, the third group includes a single lens having one or more aspheric surfaces, and the fourth group includes one or more aspheric surfaces. .

[0006]

In general, when a rear focus system is employed in a zoom lens, the entire lens system is reduced in size, and quick focusing becomes possible.
Further, features such as easy close-up photography can be obtained.

[0007] On the other hand, however, aberration fluctuation at the time of focusing becomes large, and it becomes very difficult to obtain high optical performance over the entire object distance from an object at infinity to an object at a short distance.

In particular, in a zoom lens having a large aperture ratio and a high zoom ratio, the mechanism is simplified, over the entire zoom range, and
It becomes very difficult to obtain high optical performance over the entire object distance.

For example, in the embodiment of the rear focus type zoom lens proposed in Japanese Patent Application Laid-Open No. Sho 62-24213, the second lens group having the function of zooming is arranged in the order from the object side to the object side. It is composed of a meniscus negative single lens with the convex surface facing the side, and a cemented lens in which a negative lens and a positive lens whose both lens surfaces are concave are joined. The laminated lens mainly corrects axial chromatic aberration, spherical aberration, and off-axis coma.

If the refractive power of the second lens group is increased in order to further reduce the size and increase the zoom ratio of the zoom type, the burden of aberration correction on the cemented lens surface of the second lens group becomes too large. It is difficult to achieve high performance in the entire zoom range.

Further, when the refractive power of the second lens group is increased, the curvature of each lens constituting the second lens group is reduced, and the amount of higher-order aberrations is increased. It becomes difficult to make corrections.

SUMMARY OF THE INVENTION The present invention provides a zoom lens having a short overall lens length and a simple configuration in which the entire lens system is reduced in size, has high optical performance despite a high zoom ratio, and has a reduced number of lenses. It is intended to provide an optical device using the same.

[0013]

According to a first aspect of the present invention, there is provided a zoom lens having a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power. And a fourth lens unit having a positive refractive power. In zooming from the wide-angle end to the telephoto end, the second unit is moved to the image plane side and the fourth unit is moved to the object side. The lens is moved so as to have a convex locus on the side, and the focusing is performed by moving the fourth lens group. The second lens group is sequentially moved from the object side to a negative meniscus shape having a convex surface facing the object side. The 21st lens, the negative 22nd lens with both lens surfaces concave, the positive 23rd lens with both lens surfaces convex, and the negative 2nd lens
The third lens unit is composed of a cemented lens in which four lenses are joined, and the third group is composed of one positive lens having an aspheric surface.

According to a second aspect of the present invention, in the first aspect, the radius of curvature of the image-side lens surface of the 22nd lens is R.
222, when the radius of curvature of the object-side lens surface of the 23rd lens is R231

[0015]

(Equation 3)

It is characterized by satisfying the following conditions.

According to a third aspect of the present invention, in the first or second aspect, the Abbe number of the material of the 23rd lens is ν23,
When the Abbe number of the material of the twenty-fourth lens is ν24, the following condition is satisfied: 15 <(ν24−ν23) <30 (2)

According to a fourth aspect of the present invention, in the first, second, or third aspect, the focal length of the second lens group is f2, and the radius of curvature of the cemented lens surface between the 23rd lens and the 24th lens is R234. And when

[0019]

(Equation 4)

It is characterized by satisfying the following conditions.

According to a fifth aspect of the present invention, there is provided an optical apparatus including the rear focus type zoom lens according to any one of the first to fourth aspects.

[0022]

FIG. 1 is a sectional view of an essential part of a rear focus type zoom lens according to a first embodiment of the present invention, and FIGS. 2, 3 and 4 show a wide angle end, a middle position and a telephoto end of the first embodiment. FIG. 7 is an aberration diagram at a zoom position.

FIG. 5 is a sectional view of a main part of a rear focus type zoom lens according to a second embodiment of the present invention, and FIGS.
9A is an aberration diagram at a zoom position at a wide-angle end, a middle position, and a telephoto end according to the second embodiment.

FIG. 9 is a sectional view of a principal part of a rear focus type zoom lens according to a third embodiment of the present invention, and FIGS.
FIG. 12 is an aberration diagram at a zoom position at a wide angle end, a middle position, and a telephoto end according to the third embodiment.

FIG. 13 is a sectional view of a principal part of a rear focus type zoom lens according to a fourth embodiment of the present invention, and FIGS.
5 and FIG. 16 are aberration diagrams of the fourth embodiment at zoom positions at the wide-angle end, the middle position, and the telephoto end.

FIG. 17 is a sectional view of a main portion of a rear focus type zoom lens according to a fifth embodiment of the present invention, and FIGS.
9 and 20 are aberration diagrams of the fifth embodiment at zoom positions at the wide-angle end, the middle position, and the telephoto end.

FIG. 21 is a sectional view of a main part of a rear focus type zoom lens according to a sixth embodiment of the present invention, and FIGS.
3 and FIG. 24 are aberration diagrams at the wide-angle end, a middle position, and a telephoto end according to the sixth embodiment.

FIG. 25 is a sectional view of a main part of a rear focus type zoom lens according to a seventh embodiment of the present invention, and FIGS.
7 and 28 are aberration diagrams of the seventh embodiment at zoom positions at the wide-angle end, the middle position, and the telephoto end.

In the figure, L1 is a first group having a positive refractive power, L2 is a second group having a negative refractive power, L3 is a third group having a positive refractive power, and L4 is a fourth group having a positive refractive power. . SP denotes an aperture stop, which is arranged in front of the third lens unit L3. G is a glass block such as a color separation prism, a face plate, and a filter. IP is an image plane on which an image sensor such as a CCD is arranged.

In this embodiment, when zooming from the wide-angle end to the telephoto end, the second lens unit is moved to the image plane side as indicated by an arrow, and the image plane fluctuation due to zooming is partly or entirely included in the fourth lens unit. In the present embodiment, all of them are corrected while moving along a convex locus toward the object side.

Also, a rear focus system is employed in which a part or the whole (all in the present embodiment) of the fourth group is moved on the optical axis to perform focusing. A solid line curve 4a and a dotted line curve 4b of the fourth lens group shown in the same figure show the image plane fluctuation caused by zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and an object at a short distance, respectively. The movement locus for correction is shown. The first and third units are fixed during zooming and focusing.

In the present embodiment, the fourth lens unit is moved to correct the image plane fluctuation caused by zooming, and the fourth lens unit is moved to perform focusing. In particular, curve 4 in FIG.
When zooming from the wide-angle end to the telephoto end, the lens is moved so as to have a convex trajectory toward the object side as shown in FIGS.
Thereby, the space between the third and fourth units is effectively used, and the overall length of the lens is effectively reduced.

In this embodiment, for example, when focusing from an object at infinity to an object at a short distance at the telephoto end, the fourth unit is moved forward as shown by a straight line 4c in FIG.

The most characteristic point of the present invention is that the second lens unit L2 is composed of three negative lenses and one positive lens having the above-mentioned lens shape, and four lenses of the third lens unit L3.
Is that an aspherical surface is used for one positive lens.

In a zoom lens having a high zoom ratio, in order to correct aberrations compactly and satisfactorily over the entire zoom range, the second lens group (hereinafter also referred to as a variator) mainly called a variator that performs a zooming action. It is important to minimize aberration fluctuations. However, in order to satisfy the specifications of a small-sized and high-magnification lens, it is necessary to set a strong negative refractive power to a variator that performs a magnification function, which is disadvantageous for aberration correction.

A conventional variator is disclosed, for example, in Japanese Patent Laid-Open No. 4-88.
The mainstream is a lens type having two groups and three lenses of a negative lens and a cemented lens of a negative lens and a positive lens as seen in the embodiment of Japanese Patent Publication No. 309. A variator of this type realizes a zoom lens with a high zoom ratio. If this is attempted, as the negative refractive power of the variator becomes stronger, the curvature of the cemented lens surface of the cemented lens of the negative lens and the positive lens in the variator becomes tight, and the occurrence of higher-order aberrations on this cemented lens surface will zoom. This causes the aberration fluctuation in the entire region to be large.

Therefore, in the zoom lens of the present invention,
By configuring the second lens unit L2, which greatly contributes to zooming, to the above-described lens configuration, the sharing of power of each lens is reduced, and the Petzval sum is reduced. As a result, even at a high zoom ratio, fluctuations in the image plane due to zooming are reduced. Further, the optical performance is improved by arranging an aspherical surface on the positive lens of the third lens group that receives the divergent light beam from the second lens group. In each embodiment, an aspheric surface is used for the lens surface on the object side of the third lens unit L3.

In each numerical example, the first lens unit includes a negative meniscus eleventh lens having a convex surface facing the object side, a positive lens having both lens surfaces convex, and a positive meniscus lens. I have. The fourth lens unit is composed of a negative lens having both lens surfaces concave, a positive lens having both lens surfaces convex, and a positive lens having both lens surfaces convex.

In this embodiment, by setting the lens configuration as described above, high optical performance is obtained over the entire zoom range and over the entire object distance.

The rear focus type zoom lens according to the present invention can be realized by satisfying the above-described configuration. To maintain the optical performance satisfactorily while maintaining a high zoom ratio, the following is required. It is desirable that at least one of the conditions is satisfied.

(A-1) When the radius of curvature of the lens surface on the image side of the 22nd lens is R222, and the radius of curvature of the lens surface on the object side of the 23rd lens is R231

[0042]

(Equation 5)

The following condition must be satisfied.

The variator (second lens group) is, in order from the object side, a negative lens, a negative lens, a cemented lens of a positive lens and a negative lens, and the second negative lens and the third positive lens, which were cemented lenses in the conventional type variator. An air layer was provided between the lenses to provide a gap lens function. By actively utilizing the gap lens and satisfying the conditional expression (1), the curvature of the facing lens surface of the second negative lens and the third positive lens of the variator, which was conventionally a cemented lens surface, is reduced. It is possible. By reducing the curvature of the lens surface, occurrence of higher-order spherical aberration and higher-order coma aberration is reduced.

If the lower limit of conditional expression (1) is exceeded, higher-order spherical aberration occurring in the gap lens itself will increase, making it difficult to correct aberrations. If it exceeds the upper limit of 0.5 and approaches 1, the effect of the gap lens effect will be lost. Fades.

(A-2) The Abbe number of the material of the 23rd lens is ν23, and the Abbe number of the material of the 24th lens is ν24.
The condition 15 <(ν24−ν23) <30 (2) is to be satisfied.

(A-3) The focal length of the second lens group is f
2. When the radius of curvature of the cemented lens surface of the 23rd lens and the 24th lens is R234

[0048]

(Equation 6)

The following condition must be satisfied. Since the curvature of the lens surface on the image surface side of the 22nd lens and the lens surface on the object side of the 23rd lens in the above-mentioned conditional expression (1) are reduced, chromatic aberration may be insufficiently corrected. Therefore, in order to correct the chromatic aberration of the variator in a well-balanced manner, a fourth lens is cemented behind the third lens of the variator, and by satisfying conditional expressions (2) and (3), chromatic aberration fluctuation is reduced over the entire zoom range. Hold down and good aberration correction are possible.

If the lower limit of conditional expression (2) is exceeded, chromatic aberration correction will be insufficient. If the upper limit is exceeded, the refractive index of existing glass materials will be low, and high-order spherical aberration and high-order coma aberration will occur.

If the lower limit of conditional expression (3) is surpassed, it is advantageous for chromatic aberration correction.
If the coma aberration is a problem, and if the lower limit is exceeded, chromatic aberration correction becomes insufficient, and chromatic aberration variation from the zoom wide-angle end to the telephoto end becomes difficult.

By satisfying the above conditions and suppressing the amount of high-order aberrations and aberration fluctuations in the variator as the second lens unit to a small extent, the third lens unit can be corrected with a single aspherical lens. .

Next, an embodiment of a video camera (optical apparatus) using the rear focus type zoom lens of the present invention as a photographic optical system will be described with reference to FIG.

In FIG. 29, 10 is a video camera body, 11 is a photographing optical system constituted by the zoom lens of the present invention, 12 is an image pickup device such as a CCD for receiving a subject image by the photographing optical system 11, and 13 is an image pickup device Reference numeral 12 denotes a recording unit for recording the received subject image, and reference numeral 14 denotes a finder for observing the subject image displayed on a display element (not shown). The display element includes a liquid crystal panel or the like, and displays a subject image formed on the image sensor 12.

As described above, by applying the zoom lens of the present invention to an optical device such as a video camera, an optical device having a small size and high optical performance is realized.

Hereinafter, numerical examples of the present invention will be described.

In each numerical example, Ri is the radius of curvature of the i-th surface in order from the object side, and Di is i-th surface in order from the object side.
The distance between the i-th surface and the (i + 1) -th surface, Ni and νi, are the refractive index and Abbe number of the glass of the i-th optical member in order from the object side.

The aspherical surface has an X axis in the optical axis direction, an H axis in a direction perpendicular to the optical axis, a positive traveling direction of light, R represents a paraxial radius of curvature, and each aspherical coefficient represents K, B, C, D. , E, F,

[0059]

(Equation 7)

This is represented by the following equation.

For example, the display of “eZ” is “1”.
0- ^Z ".

In the numerical examples, the last two lens surfaces are glass blocks such as a face plate and a filter. Table 1 shows the relationship between the above-described conditional expressions and various numerical values in the numerical examples.

Numerical Example 1 f = 5.90 to 57.80 fno = 1: 2.89 to 2.95 2ω = 60.6 ° to 6.4 ° r1 = 73.290 d1 = 1.30 n1 = 1.84666 ν1 = 23.9 r2 = 27.358 d2 = 5.00 n2 = 1.48749 ν2 = 70.2 r3 = -185.356 d3 = 0.20 r4 = 26.768 d4 = 3.10 n3 = 1.88300 ν3 = 40.8 r5 = 98.007 d5 = variable r6 = 51.122 d6 = 0.80 n4 = 1.88300 ν4 = 40.8 r7 = 6.964 d7 = 2.83 r8 = -31.195 d8 = 0.70 n5 = 1.88300 ν5 = 40.8 r9 = 36.000 d9 = 0.60 r10 = 14.590 d10 = 2.40 n6 = 1.84666 ν6 = 23.9 r11 = -37.403 d11 = 0.60 n7 = 1.77250 ν7 = 49.6 r12 = 64.852 d12 = variable r13 = (aperture) d13 = 2.20 * r14 = 50.190 d14 = 1.80 n8 = 1.58313 ν8 = 59.4 r15 = -29.216 d15 = variable r16 = -40.597 d16 = 0.70 n9 = 1.84666 ν9 = 23.8 r17 = 20.155 d17 = 2.80 n10 = 1.67790 ν10 = 54.9 * r18 =- 19.748 d18 = 0.50 r19 = 22.173 d19 = 1.60 n11 = 1.77250 ν11 = 49.6 r20 = -154.454 d20 = variable r21 = ∞ d21 = 3.17 n12 = 1.51680 ν12 = 64.9 r22 = ∞ Aspheric coefficient r14 surface r = 5.01902D + 01 k = -4.28770D + 01 B = -2.56450D-07 C = 1.20645D-07 D = 1.59659D-08 E = 1.63563D-09 F = -2.00233D-10 r18 surface r = -1.97484D + 01 k = 1.79416 D-01 B = 2.42450D-06 C = 1.88915D-07 D = -3.15899D-10 E = -1.16563D-10 F = 7.84552D- 13

[0064]

[Table 1]

Numerical Example 2 f = 5.91 to 57.84 fno = 1: 2.90 to 2.93 2ω = 60.4 ° to 6.4 ° r1 = 69.352 d1 = 1.30 n1 = 1.84666 ν1 = 23.9 r2 = 27.986 d2 = 5.10 n2 = 1.49700 ν2 = 81.5 r3 = -177.475 d3 = 0.20 r4 = 26.474 d4 = 3.15 n3 = 1.88300 ν3 = 40.8 r5 = 86.929 d5 = variable r6 = 46.955 d6 = 0.80 n4 = 1.88300 ν4 = 40.8 r7 = 6.790 d7 = 2.89 r8 = -34.381 d8 = 0.70 n5 = 1.88300 ν5 = 40.8 r9 = 51.533 d9 = 0.60 r10 = 12.882 d10 = 2.70 n6 = 1.84666 ν6 = 23.9 r11 = -36.547 d11 = 0.60 n7 = 1.83481 ν7 = 42.7 r12 = 29.002 d12 = variable r13 = (aperture) d13 = 2.20 * r14 = 39.181 d14 = 1.80 n8 = 1.58313 ν8 = 59.4 r15 = -32.638 d15 = variable r16 = -40.263 d16 = 0.70 n9 = 1.84666 ν9 = 23.9 r17 = 19.663 d17 = 2.80 n10 = 1.67790 ν10 = 54.9 * r18 =- 19.463 d18 = 0.50 r19 = 21.386 d19 = 1.85 n11 = 1.77250 ν11 = 49.6 r20 = -195.606 d20 = variable r21 = ∞ d21 = 3.17 n12 = 1.51680 ν12 = 64.2 r22 = ∞ Aspheric coefficient r14 surface r = 3.91813D + 01 k = -3.29956D + 01 B = 3.11655D-05 C = -2.69492D-07 D = -2.37202D-08 E = 3.10037D-09 F = -1.59613D-10 r18 surface r = -1.94634D + 01 k = 2.36307D-01 B = 7.95708D-06 C = 1.41805D-07 D = -7.93131D-09 E = 1.43526D-10 F = 3.95032D- 13

[0066]

[Table 2]

Numerical Example 3 f = 5.91 to 57.79 fno = 1: 2.90 to 3.01 2ω = 59.2 ° to 6.02 ° r1 = 68.270 d1 = 1.35 n1 = 1.84666 ν1 = 23.9 r2 = 27.077 d2 = 5.60 n2 = 1.48749 ν2 = 70.2 r3 = -127.735 d3 = 0.20 r4 = 25.006 d4 = 3.35 n3 = 1.83481 ν3 = 42.7 r5 = 84.576 d5 = variable r6 = 39.094 d6 = 0.80 n4 = 1.88300 ν4 = 40.8 r7 = 6.603 d7 = 2.92 r8 = -34.526 d8 = 0.70 n5 = 1.88300 ν5 = 40.8 r9 = 38.104 d9 = 0.60 r10 = 12.977 d10 = 2.70 n6 = 1.84666 ν6 = 23.9 r11 = -36.129 d11 = 0.60 n7 = 1.83481 ν7 = 42.7 r12 = 35.704 d12 = variable r13 = (aperture) d13 = 2.20 * r14 = 44.157 d14 = 1.80 n8 = 1.58313 ν8 = 59.4 r15 = -28.817 d15 = variable r16 = -37.417 d16 = 0.70 n9 = 1.84666 ν9 = 23.9 r17 = 18.709 d17 = 2.80 n10 = 1.67790 ν10 = 54.9 * r18 =- 20.373 d18 = 0.50 r19 = 20.715 d19 = 1.80 n11 = 1.77250 ν11 = 49.6 r20 = -92.038 d20 = variable r21 = ∞ d21 = 3.17 n12 = 1.51680 ν12 = 64.2 r22 = ∞ Aspheric coefficient r14 surface r = 4.41567D + 01 k = -3.79319D + 01 B = 1.28884D-05 C = -2.45252D-08 D = 3.55930D-08 E = 7.85890D-10 F = -2.43503D-10 r18 surface r = -2.03734D + 01 k =- 1.30631D-01 B = 3.41480D-06 C = 1.83231D-07 D = -2.36926D-09 E = -2.35948D-11 F = 3.24000D -13

[0068]

[Table 3]

Numerical Example 4 f = 6.00 to 58.83 fno = 1: 2.89 to 3.00 2ω = 58.2 ° to 6.4 ° r1 = 70.307 d1 = 1.30 n1 = 1.84666 ν1 = 23.9 r2 = 26.658 d2 = 5.10 n2 = 1.48749 ν2 = 70.2 r3 = -175.593 d3 = 0.20 r4 = 26.160 d4 = 3.15 n3 = 1.88300 ν3 = 40.8 r5 = 93.149 d5 = variable r6 = 30.946 d6 = 0.80 n4 = 1.88300 ν4 = 40.8 r7 = 6.518 d7 = 2.99 r8 = -36.767 d8 = 0.70 n5 = 1.88300 ν5 = 40.8 r9 = 38.324 d9 = 0.60 r10 = 12.527 d10 = 2.70 n6 = 1.84666 ν6 = 23.9 r11 = -65.030 d11 = 0.60 n7 = 1.83481 ν7 = 42.7 r12 = 29.726 d12 = variable r13 = (aperture) d13 = 2.20 * r14 = 42.592 d14 = 1.80 n8 = 1.58313 ν8 = 59.4 r15 = -24.975 d15 = variable r16 = -40.384 d16 = 0.70 n9 = 1.84666 ν9 = 23.9 r17 = 18.252 d17 = 2.80 n10 = 1.67790 ν10 = 54.9 * r18 =- 19.890 d18 = 0.50 r19 = 20.267 d19 = 1.80 n11 = 1.77250 ν11 = 49.6 r20 = -199.591 d20 = 5.00 r21 = ∞ d21 = 3.17 n12 = 1.51680 ν12 = 64.2 r22 = ∞ Aspheric coefficient r14 surface r = 4.25924D + 01 k = -3.51255D + 01 B = 1.27254D-05 C = -2.17513D-07 D = 2.57324D-08 E = 1.69969D-09 F = -2.13852D-10 r18 surface r = -1.98900D + 01 k =- 1.17923D-01 B = 1.39270D-07 C = 9.06409D-08 D = 2.70260D-09 E = -1.94211D-10 F = 1.65295D-12

[0070]

[Table 4]

Numerical Example 5 f = 6.01 to 59.01 fno = 1: 2.89 to 2.89 2ω = 59.8 ° to 6.4 ° r1 = 64.967 d1 = 1.30 n1 = 1.84666 ν1 = 23.9 r2 = 29.027 d2 = 5.15 n2 = 1.48749 ν2 = 70.2 r3 = -177.652 d3 = 0.20 r4 = 25.154 d4 = 3.05 n3 = 1.88481 ν3 = 42.7 r5 = 61.808 d5 = variable r6 = 34.762 d6 = 0.80 n4 = 1.88300 ν4 = 40.8 r7 = 6.432 d7 = 2.85 r8 = -27.224 d8 = 0.70 n5 = 1.88300 ν5 = 40.8 r9 = 41.608 d9 = 0.60 r10 = 13.918 d10 = 2.70 n6 = 1.84666 ν6 = 23.9 r11 = -28.983 d11 = 0.60 n7 = 1.83481 ν7 = 42.7 r12 = 53.374 d12 = variable r13 = (aperture) d13 = 2.20 * r14 = 36.600 d14 = 1.80 n8 = 1.58313 ν8 = 59.4 r15 = -28.083 d15 = variable r16 = -44.150 d16 = 0.70 n9 = 1.84666 ν9 = 23.9 r17 = 20.380 d17 = 2.80 n10 = 1.67790 ν10 = 54.9 r18 = -22.314 d18 = 0.50 r19 = 29.859 d19 = 1.95 n11 = 1.77250 ν11 = 49.6 r20 = -94.191 d20 = 5.00 r21 = ∞ d21 = 3.17 n12 = 1.51680 ν12 = 64.2 r22 = ∞ Aspheric coefficient r14 surface r = 3.66003D + 01 k = -2.21824D + 01 B = 1.91217D-05 C = -9.28714D-07 D = 3.22454D-08 E = 1.31625D-09 F = -8.90730D-1

[0072]

[Table 5]

Numerical Example 6 f = 6.01 to 59.00 fno = 1: 2.89 to 2.93 2ω = 59.2 ° to 6.4 ° r1 = 70.577 d1 = 1.30 n1 = 1.84666 ν1 = 23.9 r2 = 28.102 d2 = 5.25 n2 = 1.48749 ν2 = 70.2 r3 = -135.912 d3 = 0.20 r4 = 25.710 d4 = 3.20 n3 = 1.83481 ν3 = 42.7 r5 = 85.671 d5 = variable r6 = 48.172 d6 = 0.80 n4 = 1.88300 ν4 = 40.8 r7 = 6.784 d7 = 2.81 r8 = -34.302 d8 = 0.70 n5 = 1.88300 ν5 = 40.8 r9 = 41.261 d9 = 0.60 r10 = 13.312 d10 = 2.70 n6 = 1.84666 ν6 = 23.9 r11 = -35.939 d11 = 0.60 n7 = 1.83481 ν7 = 42.7 r12 = 36.888 d12 = variable r13 = (aperture) d13 = 2.20 * r14 = 41.177 d14 = 1.80 n8 = 1.58313 ν8 = 59.4 r15 = -29.537 d15 = variable r16 = -39.851 d16 = 0.70 n9 = 1.84666 ν9 = 23.9 r17 = 19.986 d17 = 2.80 n10 = 1.67790 ν10 = 54.9 * r18 =- 20.589 d18 = 0.50 r19 = 22.582 d19 = 1.95 n11 = 1.77250 ν11 = 49.6 r20 = -116.734 d20 = 5.00 r21 = ∞ d21 = 3.17 n12 = 1.51680 ν12 = 64.2 r22 = ∞ Aspheric coefficient r14 surface r = 4.11772D + 01 k = -3.06458D + 01 B = 1.49123D-05 C = -9.25985D-08 D = 1.59599D-08 E = 1.57343D-09 F = -1.66189D-10 r18 surface r = -2.05892D + 01 k =- 1.61879D-01 B = 2.46942D-07 C = 2.33996D-07 D = -6.83658D-09 E = 2.80776D-11 F = 1.30665D-12

[0074]

[Table 6]

Numerical Example 7 f = 6.03-59.02 fno = 1: 2.87-2.89 2ω = 59.0 ° -6.4 ° r1 = 62.095 d1 = 1.30 n1 = 1.84666 ν1 = 23.9 r2 = 28.268 d2 = 4.70 n2 = 1.48749 ν2 = 70.2 r3 = -228.219 d3 = 0.20 r4 = 25.507 d4 = 2.95 n3 = 1.83481 ν3 = 42.7 r5 = 67.193 d5 = variable r6 = 26.771 d6 = 0.80 n4 = 1.88300 ν4 = 40.8 r7 = 6.365 d7 = 3.15 r8 = -23.692 d8 = 0.70 n5 = 1.88300 ν5 = 40.8 r9 = 74.962 d9 = 0.60 r10 = 13.790 d10 = 2.50 n6 = 1.84666 ν6 = 23.9 r11 = -49.225 d11 = 0.60 n7 = 1.77250 ν7 = 49.6 r12 = 33.632 d12 = variable r13 = (aperture) d13 = 3.00 * r14 = 41.241 d14 = 2.00 n8 = 1.58313 ν8 = 59.4 r15 = -25.592 d15 = variable r16 = -29.471 d16 = 0.70 n9 = 1.84666 ν9 = 23.9 r17 = 25.818 d17 = 2.85 n10 = 1.67790 ν10 = 54.9 r18 = -17.943 d18 = 0.50 r19 = 28.075 d19 = 1.80 n11 = 1.77250 ν11 = 49.6 r20 = -137.571 d20 = 5.00 r21 = ∞ d21 = 3.17 n12 = 1.51680 ν12 = 64.2 r22 = ∞ Aspheric coefficient r14 surface r = 4.12412D + 01 k = -2.09653D + 01 B = -9.81742D-06 C = -2.33933D-07 D = 7.49268D-09 E = 2.16763D-09 F = -1.21645D-10

[0076]

[Table 7]

[0077]

[Table 8]

[0078]

According to the present invention, the entire lens system is reduced in size, has a high optical performance in spite of a high zoom ratio, and has a simple total lens length with a reduced number of lenses. A short zoom lens and an optical device using the same can be achieved.

In addition, according to the present invention, a rear focus having a high zoom ratio as high as 10 times, and having a high optical performance which is excellent in correcting aberrations over the entire zoom range with a small size and light weight. Type zoom lens can be achieved.

[Brief description of the drawings]

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

FIG. 2 is an aberration diagram at a wide-angle end according to Numerical Embodiment 1 of the present invention.

FIG. 3 is an intermediate aberration diagram of the numerical example 1 of the present invention.

FIG. 4 is an aberration diagram at a telephoto end in Numerical Embodiment 1 of the present invention.

FIG. 5 is a sectional view of a lens according to a numerical example 2 of the present invention.

FIG. 6 is an aberration diagram at a wide angle end according to Numerical Example 2 of the present invention.

FIG. 7 is an intermediate aberration diagram of the numerical example 2 of the present invention.

FIG. 8 is an aberration diagram at a telephoto end in Numerical Example 2 of the present invention.

FIG. 9 is a sectional view of a lens according to a numerical example 3 of the present invention.

FIG. 10 is an aberration diagram at a wide angle end according to Numerical Example 3 of the present invention.

FIG. 11 is an intermediate aberration diagram of the numerical example 3 of the present invention.

FIG. 12 is an aberration diagram at a telephoto end in Numerical Example 3 of the present invention.

FIG. 13 is a sectional view of a lens according to a numerical example 4 of the present invention.

FIG. 14 is an aberration diagram at a wide angle end according to Numerical Example 4 of the present invention.

FIG. 15 is an intermediate aberration diagram of the numerical example 4 of the present invention.

FIG. 16 is an aberration diagram at a telephoto end in Numerical Example 4 of the present invention.

FIG. 17 is a lens sectional view of a numerical example 5 of the present invention;

FIG. 18 is an aberration diagram at a wide angle end according to Numerical Example 5 of the present invention.

FIG. 19 is an intermediate aberration diagram of the numerical example 5 of the present invention.

FIG. 20 is an aberration diagram at a telephoto end in Numerical Example 5 of the present invention.

FIG. 21 is a sectional view of a lens according to a numerical example 6 of the present invention.

FIG. 22 is an aberration diagram at a wide angle end according to Numerical Example 6 of the present invention.

FIG. 23 is an intermediate aberration diagram of the numerical example 6 of the present invention.

FIG. 24 is an aberration diagram at a telephoto end in Numerical Example 6 of the present invention.

FIG. 25 is a sectional view of a lens according to a numerical example 7 of the present invention.

FIG. 26 is an aberration diagram at a wide angle end according to Numerical Example 7 of the present invention.

FIG. 27 is an intermediate aberration diagram of the numerical example 7 of the present invention.

FIG. 28 is an aberration diagram at a telephoto end in Numerical Example 7 of the present invention.

FIG. 29 is a schematic diagram of a main part of the optical apparatus of the present invention.

[Explanation of symbols]

 L1 First group L2 Second group L3 Third group L4 Fourth group SP Aperture G Glass block IP Image plane d d line g g line ΔM Meridional image plane ΔS Sagittal image plane

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H087 KA02 KA03 MA15 PA08 PA20 PB11 QA02 QA07 QA17 QA21 QA25 QA34 QA41 QA46 RA05 RA12 RA13 RA32 RA41 RA42 RA43 SA23 SA27 SA29 SA32 SA63 SA65 SA72 SA74 SB04 SB15 SB22 SB34

Claims (5)

[Claims] 1. Four lenses of a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power in order from the object side. When zooming from the wide-angle end to the telephoto end, the second unit is moved to the image plane side, and the fourth unit is moved to have a locus convex toward the object side. In focusing, the fourth unit is moved, and the second unit is sequentially moved from the object side to the negative second meniscus lens having a convex surface facing the object side, and both lens surfaces having a concave concave surface. 2
Two lenses, each composed of a cemented lens in which a positive twenty-third lens and a negative twenty-fourth lens whose both lens surfaces are convex are joined;
A rear focus type zoom lens, wherein the third group is constituted by a single positive lens having an aspheric surface. 2. When the radius of curvature of the lens surface on the image side of the 22nd lens is R222, and the radius of curvature of the lens surface on the object side of the 23rd lens is R231. 2. The rear focus type zoom lens according to claim 1, wherein the following condition is satisfied. 3. The Abbe number of the material of the 23rd lens is ν.
23. The rear focus type zoom lens according to claim 1, wherein a condition of 15 <(ν24−ν23) <30 is satisfied when an Abbe number of a material of the 24th lens is ν24. 4. When the focal length of the second lens group is f2 and the radius of curvature of the cemented lens surface between the 23rd lens and the 24th lens is R234. 4. The rear focus type zoom lens according to claim 1, wherein the following condition is satisfied. 5. An optical apparatus comprising the rear focus type zoom lens according to claim 1.