JP2006064904A - Optical system equipped with cemented lens and imaging apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical system capable of obtaining a zoom lens excellent in image forming performance with a small number of lenses and realizing the manufacture of a thin and high-performance digital camera or a video camera, and to provide an imaging apparatus using the same. <P>SOLUTION: In the optical system equipped with the cemented lens having a bonded surface on an optical axis, air contact surfaces being a light beam incident side and a light beam emitting side in the cemented lens G2 are aspherical, and at least one bonded surface of the cemented lens G2 satisfies a following condition. (1) 6.4<¾(r/R)¾, provided that r is the radius of curvature on the optical axis of the connecting surface and R is the maximum diameter of the connecting surface. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical system including a cemented lens and an image pickup apparatus using the optical system, and in particular, a zoom lens having a configuration suitable for a digital camera or a video camera while achieving a reduction in thickness by devising an optical system portion and the same. The present invention relates to an image pickup apparatus using the.

  In recent years, zoom lenses, particularly digital camera zoom lenses, are increasingly required to be thin. Compared to a silver salt camera, a digital camera with a small imaging device can generally be designed with a small lens, but the manufacturing error of lens parts and the mounting error of the lens barrel become relatively large, and the performance is reduced by eccentricity. Since it deteriorates, it tends to reduce the yield. In addition, in order to reduce the camera thickness, it is necessary to reduce the number of lenses constituting the zoom lens. In many cases, aberration is corrected by using aspheric surfaces with a small number of lenses.

  However, in such an optical system, the imaging performance is likely to deteriorate due to the relative decentration between the aspheric lenses due to manufacturing errors, so it is difficult to achieve both mass production with a high yield and thinning.

Examples of reducing the number of lenses by using many aspheric surfaces include Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, and the like. In any case, the decentration sensitivity of the second lens group is aspheric. Moreover, it cannot be said that the total thickness of each group is sufficiently thinned.
Japanese Patent Laid-Open No. 1-183616 JP-A-10-282416 JP-A-11-95102 JP-A-11-142734

  As described above, in the prior art, it has been difficult to achieve both a reduction in thickness while making sufficient aberration correction using aspheric surfaces and a reduction in yield due to manufacturing errors.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a zoom lens having a high imaging performance that is stable and compact from infinity to a short distance. By sufficiently correcting aberrations, astigmatism and lateral chromatic aberration, it is possible to reduce the thickness of the camera in the storage state compared to the conventional technology, and to provide an optical system suitable for digital cameras and video cameras. is there.

  In order to achieve the above object, an optical system including the first cemented lens of the present invention is an optical system including a cemented lens having a cemented surface on the optical axis, and the incident side of the light beam in the cemented lens. The air contact surface on the exit side is aspherical, and at least one cemented surface in the cemented lens satisfies the following conditions.

6.4 <| (r / R) | (1)
Here, r is the radius of curvature of the joint surface on the optical axis, and R is the maximum diameter of the joint surface.

  Hereinafter, the reason and action of the above configuration in the optical system including the first cemented lens of the present invention will be described.

  When the cemented lens is configured while adjusting the relative decentration of the aspherical surfaces before and after the cemented surface, the influence on the performance other than the adjusted portion can be reduced.

  When the radius of curvature of the joint surface on the optical axis becomes smaller than the lower limit value 6.4 of the conditional expression (1), the radius of curvature of the joint surface becomes smaller than the diameter of the joint surface. For this reason, relative decentration between the entrance surface and the exit surface of the lens at the time of cementing is likely to occur, and complex decentering aberrations due to the aspheric surfaces of the entrance surface and the exit surface are likely to occur.

  An optical system including the second cemented lens according to the present invention is characterized in that, in the first optical system, the cemented lens includes a plurality of cemented surfaces.

  Hereinafter, the reason and action of the above configuration in the optical system including the second cemented lens of the present invention will be described.

  In this case, the cemented lens is composed of a plurality of lenses. Therefore, it becomes easy to correct chromatic aberration, astigmatism, field curvature, and the like. In addition, since there are a plurality of bonding surfaces, it is possible to perform bonding that cancels the influence of relative eccentricity. The number of lenses constituting the cemented lens may be four or more, limited to three.

  The optical system including the third cemented lens according to the present invention is characterized in that the number of lenses constituting the cemented lens is three in the second optical system.

  The reason and action of the above configuration in the optical system including the third cemented lens of the present invention will be described below. In order to reduce the total length of the optical system while suppressing the influence of decentering, the cemented lens is 3 It is preferable to use a single lens.

An optical system including the fourth cemented lens of the present invention is the first to third optical systems, wherein the optical system is an imaging optical system, and the imaging optical system is
A positive lens group having positive refractive power including the cemented lens;
A negative lens group of negative refractive power located on the object side of the positive lens group with a variable interval at the time of zooming;
And an aperture stop disposed between the exit surface of the negative lens group and the exit surface of the positive lens group.

  Hereinafter, the reason and action of the above configuration in the optical system including the fourth cemented lens of the present invention will be described.

  By changing the distance between the positive lens group and the negative lens group, an imaging optical system having a zooming function can be obtained.

  At this time, since the aperture stop is in the vicinity or inside of the positive lens group, the diameter of the second lens group can be made smaller than the other lens groups, which is advantageous for increasing the refractive power.

  On the other hand, since the positive lens group has a small lens diameter, increasing the refractive power also increases the influence on the eccentricity of the lenses in the positive lens group. Therefore, if the cemented lens of the present invention is used, it is possible to correct aberrations favorably on the aspherical surface even when the refractive power is increased, and it is possible to reduce the influence of decentering between the lenses.

An optical system including a fifth cemented lens according to the present invention includes, in order from the object side to the image plane side, a first lens group having a negative refractive power, and the first lens group with a variable interval at the time of zooming. A second lens group having a positive refractive power located closer to the image plane side,
The second lens group is composed of three lenses,
The most image side lens and the object side lens of the second lens group are configured as a cemented lens joined on a surface on the optical axis,
The refractive index n ₂₃ for the d-line of the lens closest to the image plane and the refractive index n ₂₂ for the d-line of the object-side lens cemented with the lens satisfy the following conditions: is there.

0.31 <| n ₂₂ −n ₂₃ | (2)
The reason and action of the above configuration in the optical system including the fifth cemented lens of the present invention will be described below.

  If the second lens group is composed of three lenses, it is possible to easily balance the aberration correction and miniaturization in the second lens group.

  Furthermore, providing a cemented lens in the second lens group is advantageous for correcting chromatic aberration.

  On the other hand, if the curvature radius of the joint surface is too small, the influence of eccentricity during joining becomes large. Therefore, by appropriately securing the refractive index difference of the lenses to be joined so as to satisfy the conditional expression (2), the radius of curvature can be increased while securing the refractive power at the joint surface, and therefore the influence of eccentricity during joining. Can be reduced.

  An optical system including a sixth cemented lens according to the present invention is the fifth optical system, wherein the three lenses are a positive lens, a negative lens, and a positive lens in order from the object side, and the most optical surface side of the optical system. The cemented surface, which is the object side surface of the positive lens, is a refracting surface having a negative refractive power.

  Hereinafter, the reason and action of the above configuration in the optical system including the sixth cemented lens of the present invention will be described.

  By giving negative refractive power to the cemented surface between the negative lens and the positive lens, the principal point of the entire second lens group can be closer to the object side. Thereby, the distance between the principal points of the first lens unit having negative refracting power and the second lens unit having positive refracting power can be reduced at the telephoto end, which is advantageous for increasing the zoom ratio.

An optical system including a seventh cemented lens according to the present invention includes a first lens group having a negative refractive power in order from the object side to the image plane side, and the first lens group with a variable interval at the time of zooming. A second lens group having a positive refractive power located closer to the image plane side,
The second lens group is composed of three lenses,
The most image side lens and the object side lens of the second lens group are configured as a cemented lens joined on a surface on the optical axis,
An aperture stop is disposed between the exit surface of the first lens group and the entrance surface of the cemented lens,
The d-line reference Abbe number ν ₂₃ of the lens closest to the image plane and the d-line reference Abbe number ν _{22 of} the lens cemented with the lens satisfy the following conditions. .

40.3 <| ν ₂₂ −ν ₂₃ | (3)
Hereinafter, the reason and action of the above configuration in the optical system including the seventh cemented lens of the present invention will be described.

  If the second lens group is composed of three lenses, it is possible to easily balance the aberration correction and miniaturization in the second lens group.

  Furthermore, providing a cemented lens in the second lens group is advantageous for correcting chromatic aberration.

  Since this cemented lens is located on the image plane side close to the stop, satisfying the conditional expression (3) is advantageous in correcting axial chromatic aberration and lateral chromatic aberration.

  The optical system including the eighth cemented lens according to the present invention is characterized in that, in the fifth to seventh optical systems, the following conditional expression is satisfied.

−1.8 <f ₁ / f _w <−1.2 (4)
1.1 <f ₂ / f _w <1.5 (5)
1.7 < _ft / _fw <2.5 (6)
Where f ₁ is the focal length of the first lens group, f ₂ is the focal length of the second lens group, _fw is the focal length of the entire optical system at the wide angle end, and _ft is the entire optical system at the telephoto end. Is the focal length.

  Hereinafter, the reason and action of the above configuration in the optical system including the eighth cemented lens of the present invention will be described.

  Conditional expressions (4) and (5) define the appropriate refractive power of the first lens group and the second lens group at the wide-angle end focal length, and conditional expression (6) simultaneously defines the zoom ratio. It is.

  If the lower limit of -1.8 in conditional expression (4) and the upper limit of 1.5 in conditional expression (5) are exceeded, the refractive power of the lens group will be weakened, and the moving space required for zooming will increase, The overall length of the lens system increases.

  If the upper limit value -1.2 of conditional expression (4) and the lower limit value 1.1 of conditional expression (5) are exceeded, the number of lenses increases for aberration correction in each lens group, and the size is reduced when retracted. Becomes difficult.

  Conditional expression (6) defines a zoom ratio suitable from the viewpoint of user needs and miniaturization.

More preferably,
The lower limit value of conditional expression (4) may be set to -1.7.

  The upper limit value of conditional expression (4) may be −1.3.

  The lower limit value of conditional expression (5) may be 1.2.

  The upper limit value of conditional expression (5) may be set to 1.4.

  In the optical system including the ninth cemented lens according to the present invention, in the fifth to eighth optical systems, half or more of the air contact surfaces are aspheric surfaces, and the aspheric shape is expressed by the following formula (A). The conic coefficient K when approximated to 0 is 0 or less.

x = (y ² / r) / [1+ {1- (K + 1) (y / r) ² } ^1/2 ]
+ A ₄ y ⁴ + A ₆ y ⁶ + A ₈ y ⁸ + A ₁₀ y ¹⁰ (A)
In the aspherical shape, x is an optical axis with the light traveling direction being positive, y is a direction orthogonal to the optical axis, r is a paraxial radius of curvature, K is a conical coefficient, A ₄ , A ₆ , A ₈ and A ₁₀ are fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients, respectively.

  Hereinafter, the reason and action of the above configuration in the optical system including the ninth cemented lens according to the present invention will be described. When such a configuration satisfies such a condition, coma aberration / field curvature Can be corrected in a balanced manner.

An optical system including a tenth cemented lens according to the present invention is the fifth to ninth optical systems, wherein the first lens group is composed of two lenses of a negative lens and a positive lens in order from the object side. And
The second lens group is composed of three lenses of a positive lens, a negative lens, and a positive lens in order from the object side,
Further, a third lens group including one positive lens with a variable interval is provided on the image plane side of the second lens group, and the optical system is configured as a three-group zoom lens.

  In the following, the reason and action of the above configuration in the optical system including the tenth cemented lens of the present invention will be described. Such a configuration has a field angle at the wide-angle end, downsizing of the entire length when retracted, and aberrations. This is a preferable lens arrangement for ensuring balance.

An optical system having an eleventh cemented lens according to the present invention is the fifth to ninth optical systems, wherein the first lens group is composed of two lenses of a negative lens and a positive lens in order from the object side. And
The second lens group is composed of three lenses of a positive lens, a negative lens, and a positive lens in order from the object side,
The optical system is configured as a two-group zoom lens.

  Hereinafter, the reason and action of the above-described configuration in the optical system including the eleventh cemented lens of the present invention will be described. Such a configuration has a field angle at the wide-angle end, downsizing of the total length when retracted, and aberrations. This is a preferable lens arrangement for ensuring balance.

An optical system including the twelfth cemented lens of the present invention is the tenth to eleventh optical systems, wherein the first lens group is moved in order from the object side, and the image side curvature radius absolute value is the object side curvature radius absolute value. Consisting of two lenses: a smaller negative lens and a positive meniscus lens with a concave surface facing the image side,
In order from the object side, the second lens group includes, in order from the object side, a positive lens in which the absolute value of the object side curvature radius is smaller than the absolute value of the image side curvature radius, and a negative lens in which the absolute value of the image side curvature radius is smaller than the absolute value of the object side curvature radius. And the object side surface radius of curvature is composed of three positive lenses having a smaller image side surface radius of curvature absolute value.

  Hereinafter, the reason and action of the above configuration in the optical system including the twelfth cemented lens of the present invention will be described. Such a configuration corrects on-axis aberrations and off-axis aberrations in a balanced manner with a small number of lenses. Therefore, the lens configuration is advantageous. Further, by making the principal point of the second lens group closer to the first lens group, the focal length on the telephoto end side can be easily extended while being small.

  An optical system including the thirteenth cemented lens of the present invention is the twelfth optical system, wherein the distance on the optical axis between the negative lens and the positive lens in the first lens group is 1.4 mm or more and 1.6 mm. It is characterized by the following.

  Hereinafter, the reason and action of the above configuration in the optical system including the thirteenth cemented lens of the present invention will be described. This condition determines the size of the lens while making the principal point of the first lens group closer to the object side. This is a condition for making it moderately small.

  An optical system including the fourteenth cemented lens according to the present invention is characterized in that in the fifth to thirteenth optical systems, the three lenses of the second lens group are configured by a cemented triplet lens. is there.

  The reason and action of the above configuration in the optical system including the fourteenth cemented lens according to the present invention will be described below. This configuration corrects aberration, reduces the size of the second lens group, and reduces the influence of decentration. It is advantageous to perform.

  An optical system provided with the fifteenth cemented lens of the present invention is characterized in that, in the fourteenth optical system, the thickness of the cemented triplet lens on the optical axis is 6 mm or less.

  The reason and action of the above configuration in the optical system including the fifteenth cemented lens of the present invention will be described below. The cemented triplet lens arranged in the second lens group is advantageous for reducing the size of the lens system. Therefore, by setting the thickness of the cemented triplet lens of the second lens group to 6 mm or less, the thickness when retracted can be reduced.

  An optical system including the sixteenth cemented lens according to the present invention is characterized in that, in the fifteenth optical system, the thickness of the cemented triplet lens on the optical axis is 5.5 mm or less.

  Hereinafter, the reason and action of the above configuration in the optical system including the sixteenth cemented lens of the present invention will be described. By satisfying this condition, the thickness when retracted can be further reduced.

  An optical system including the seventeenth cemented lens according to the present invention is the fourteenth to sixteenth optical system, wherein an aperture stop is arranged immediately before the object side of the cemented triplet lens, The thickness ratio of the cemented triplet lens is 1.4 or more.

  The reason and action of the above configuration in the optical system including the seventeenth cemented lens of the present invention will be described below.

  With such a configuration, since each refracting surface of the cemented lens can be appropriately dispersed between those close to the aperture stop and those far from the aperture stop, it becomes easy to favorably correct aberrations occurring in the second lens group. In addition, by adjusting the distance between the surfaces appropriately, adjustment of the main point, facilitation of lens manufacture, and the like are facilitated.

  An eighteenth imaging device of the present invention includes an optical system including fifth to ninth cemented lenses, and further includes an electronic imaging element for converting an optical image obtained by the optical system into an electric signal. It is characterized by.

  The reason and action of the above configuration in the eighteenth imaging apparatus of the present invention will be described below.

  The optical system of the present invention is advantageous for a lens configuration that brings the emitted light beam close to vertical. Therefore, it can be applied to an imaging apparatus using an electronic imaging element.

  According to a nineteenth image pickup apparatus of the present invention, in the eighteenth image pickup apparatus, an incident angle of the chief ray at the maximum image height position at the wide angle end of the optical system is 15 ° or more and less than 30 °. It is a feature.

  The reason and action of the above-described configuration in the nineteenth image pickup apparatus of the present invention will be described below. This condition is a condition for balancing the influence on the oblique incidence characteristic of the electronic image pickup device with the small size. If the chief ray incident angle at the wide-angle end becomes smaller than the lower limit of 15 °, the optical system becomes larger. If the upper limit of 30 ° is exceeded, the angle of incidence on the electronic image sensor becomes small and color shading tends to occur.

  According to a twentieth image pickup device of the present invention, in the nineteenth image pickup device, an incident angle of the principal ray at the maximum image height position at the wide angle end of the optical system is 16 ° or more. Is.

  The reason and action of the above configuration in the twentieth imaging apparatus of the present invention will be described below. By satisfying this condition, it is advantageous for further downsizing.

  In the present invention, it goes without saying that a plurality of the above-described conditions of the invention may be satisfied simultaneously.

  According to the present invention, a zoom lens having excellent imaging performance can be obtained with a small number of sheets, and a thin and high-performance digital camera or video camera can be manufactured.

  Examples 1 to 7 of the zoom optical system provided with the cemented lens of the present invention will be described below. FIGS. 1 to 7 show lens cross-sectional views at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on an object point at infinity in Examples 1 to 7, respectively. In the drawing, the first lens group is indicated by G1, the aperture stop is indicated by S, the second lens group is indicated by G2, the third lens group is indicated by G3, a parallel plate such as a filter is indicated by P, and the image plane is indicated by I.

  As shown in FIG. 1, the zoom optical system according to the first exemplary embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves in a concave locus on the object side, and at the telephoto end is located closer to the image plane than the wide-angle end, The aperture stop S and the second lens group G2 move monotonously as a unit to the object side.

  In order from the object side, the first lens group G1 includes a negative meniscus lens having a convex surface facing the object side, and a positive meniscus lens having a convex surface facing the object side. The second lens group G2 includes a biconvex positive lens and both lenses. The aspherical surface is composed of a cemented lens composed of a concave negative lens and a biconvex positive lens. The aspherical surface is the surface of the negative meniscus lens of the first lens group G1 and the most cemented lens of the second lens group G2. It is used for the three surfaces of the object side surface and the most image surface side surface.

  As shown in FIG. 2, the zoom optical system according to the second exemplary embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves in a concave locus on the object side, and at the telephoto end is located closer to the image plane than the wide-angle end, The aperture stop S and the second lens group G2 move monotonously as a unit to the object side.

  In order from the object side, the first lens group G1 includes a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side. The second lens group G2 has a convex surface facing the object side. A positive meniscus lens, a negative meniscus lens having a convex surface facing the object side, and a biconvex positive lens. The aspherical surface is a surface on the image surface side of the negative meniscus lens in the first lens group G1, and The three lens cemented lenses of the second lens group G2 are used for the three surfaces of the most object side surface and the most image side surface.

  As shown in FIG. 3, the zoom optical system of Embodiment 3 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves in a concave locus on the object side, and at the telephoto end is located closer to the image plane than the wide-angle end, The aperture stop S and the second lens group G2 move monotonously as a unit to the object side.

  In order from the object side, the first lens group G1 includes a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side. The second lens group G2 has a convex surface facing the object side. A positive meniscus lens, a negative meniscus lens having a convex surface facing the object side, and a biconvex positive lens. The aspherical surface is a surface on the image surface side of the negative meniscus lens in the first lens group G1, and The three lens cemented lenses of the second lens group G2 are used for the three surfaces of the most object side surface and the most image side surface.

  As shown in FIG. 4, the zoom optical system according to the fourth exemplary embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves in a concave locus on the object side, and at the telephoto end is located closer to the object side than the wide-angle end, The aperture stop S and the second lens group G2 move monotonously to the object side.

  In order from the object side, the first lens group G1 includes a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side. The second lens group G2 has a convex surface facing the object side. A positive meniscus lens, a negative meniscus lens having a convex surface facing the object side, and a biconvex positive lens. The aspherical surface is a surface on the image surface side of the negative meniscus lens in the first lens group G1, and The three lens cemented lenses of the second lens group G2 are used for the three surfaces of the most object side surface and the most image side surface.

  As shown in FIG. 5, the zoom optical system according to the fifth exemplary embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves in a concave locus on the object side, and at the telephoto end is located closer to the image plane than the wide-angle end, The aperture stop S and the second lens group G2 move monotonously as a unit to the object side.

  In order from the object side, the first lens group G1 includes a negative meniscus lens having a convex surface facing the object side, and a positive meniscus lens having a convex surface facing the object side. The second lens group G2 includes a biconvex positive lens and both lenses. The aspherical surface is composed of a cemented lens composed of a concave negative lens and a biconvex positive lens. The aspherical surface is the surface of the negative meniscus lens of the first lens group G1 and the most cemented lens of the second lens group G2. It is used for the three surfaces of the object side surface and the most image surface side surface.

  As shown in FIG. 6, the zoom optical system according to the sixth embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, a second lens group G2 having a positive refractive power, a positive The first lens group G1 moves in a concave locus on the object side when zooming from the wide-angle end to the telephoto end, and the telephoto end. At the end, it is located closer to the object side than the wide-angle end, the aperture stop S and the second lens group G2 move monotonously and integrally to the object side, and the third lens group G3 moves along a concave locus on the object side, At the telephoto end, it is located closer to the object side than the wide-angle end.

  In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface directed toward the object side, and the second lens group G2 includes a positive meniscus lens having a convex surface directed toward the object side and an object. The third lens group G3 is composed of a single biconvex positive lens, and the aspherical surface is a biconcave of the first lens group G1. It is used for the three surfaces of the negative lens on the image surface side and the most object side surface and the most image surface side surface of the triplet cemented lens of the second lens group G2.

  As shown in FIG. 7, the zoom optical system according to the seventh embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, a second lens group G2 having a positive refractive power, The first lens group G1 moves to the object side during zooming from the wide-angle end to the telephoto end, and the aperture stop S and the second lens group. G2 integrally moves monotonically toward the object side, and the third lens group G3 moves along a locus of a concave shape on the object side, and is located closer to the object side than the wide-angle end at the telephoto end.

  In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface directed toward the object side, and the second lens group G2 includes a positive meniscus lens having a convex surface directed toward the object side and an object. The third lens group G3 is composed of a single biconvex positive lens, and the aspherical surface is a biconcave of the first lens group G1. It is used for the three surfaces of the negative lens on the image surface side and the most object side surface and the most image surface side surface of the triplet cemented lens of the second lens group G2.

The numerical data of each of the above embodiments are shown below. Symbols are the above, f is the total focal length, _FNO is the F number, ω is the half angle of view, WE is the wide angle end, ST is the intermediate state, TE telephoto end, r _1, r ₂ ... curvature radius of each lens surface, d _1, d ₂ ... the spacing between the lens surfaces, n _d1, n _d2 ... d-line refractive index of each lens, [nu _d1 , Ν _d2 ... Is the Abbe number of each lens. The aspherical shape is represented by the following formula, where x is an optical axis with the light traveling direction being positive, and y is a direction orthogonal to the optical axis.

x = (y ² / r) / [1+ {1- (K + 1) (y / r) ² } ^1/2 ]
_{^{A 4 y 4 + A 6 y}} 6 + A 8 y 8 + A 10 y 10 + A 12 y 12
Here, r is a paraxial radius of curvature, K is a conical coefficient, and A ₄ , A ₆ , A ₈ , and A ₁₀ are fourth, sixth, eighth, tenth, and twelfth aspheric coefficients, respectively.

  In the numerical data of the following examples, the value indicating the length is the length in mm.

Example 1
r ₁ = 73.835 d ₁ = 1.20 n _d1 = 1.80610 ν _d1 = 40.74
r ₂ = 3.773 (aspherical surface) d ₂ = 1.60
r ₃ = 6.842 d ₃ = 1.70 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 17.434 d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = -0.20
r ₆ = 4.407 (aspherical surface) d ₆ = 1.80 n _d3 = 1.74330 ν _d3 = 49.33
r ₇ = -200.000 d ₇ = 0.80 n _d4 = 1.80518 ν _d4 = 25.42
r ₈ = 5.242 d ₈ = 2.76 n _d5 = 1.48749 ν _d5 = 70.44
r ₉ = -26.974 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.30 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₁ = ∞ d ₁₁ = (variable)
r ₁₂ = ∞ (image plane)
Aspheric coefficient 2nd surface K = -3.269
A ₄ = 6.23206 × 10 ^-3
A ₆ = -3.63433 × 10 ^-4
A ₈ = 2.22372 × 10 ^-5
A ₁₀ = -6.62190 × 10 ^-7
6th page K = -3.180
A ₄ = 4.24973 × 10 ^-3
A ₆ = -1.98823 × 10 ^-4
A ₈ = 3.04193 × 10 ^-5
A ₁₀ = -2.69865 × 10 ^-6
Surface 9 K = 0.000
A ₄ = 4.93949 × 10 ^-3
A ₆ = -1.34150 × 10 ^-4
A ₈ = 1.74837 × 10 ^-4
A ₁₀ = -1.48151 × 10 ^-5
Zoom data (∞)
WE ST TE
f (mm) 5.900 8.200 11.500
F _NO 3.62 4.18 5.00
ω (°) 32.8 24.1 17.5
d ₄ 7.29 3.84 1.30
d ₉ 6.56 8.37 10.96
d ₁₁ 1.18 1.18 1.18.

Example 2
r ₁ = 31.097 d ₁ = 1.20 n _d1 = 1.80610 ν _d1 = 40.74
r ₂ = 3.332 (aspherical surface) d ₂ = 1.60
r ₃ = 6.133 d ₃ = 1.70 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 13.488 d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = -0.20
r ₆ = 4.379 (aspherical surface) d ₆ = 1.80 n _d3 = 1.74330 ν _d3 = 49.33
r ₇ = 50.000 d ₇ = 0.84 n _d4 = 1.80518 ν _d4 = 25.42
r ₈ = 4.563 d ₈ = 2.76 n _d5 = 1.48749 ν _d5 = 70.44
r ₉ = -15.315 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.30 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₁ = ∞ d ₁₁ = (variable)
r ₁₂ = ∞ (image plane)
Aspheric coefficient 2nd surface K = -3.146
A ₄ = 8.64879 × 10 ^-3
A ₆ = -5.82477 × 10 ^-4
A ₈ = 4.16275 × 10 ^-5
A ₁₀ = -1.37380 × 10 ^-6
6th page K = -3.878
A ₄ = 5.28562 × 10 ^-3
A ₆ = -3.13553 × 10 ^-4
A ₈ = 3.29362 × 10 ^-5
A ₁₀ = -2.13641 × 10 ^-6
Surface 9 K = 0.000
A ₄ = 4.42791 × 10 ^-3
A ₆ = -4.55843 × 10 ^-5
A ₈ = 1.14056 × 10 ^-4
A ₁₀ = -6.29055 × 10 ^-6
Zoom data (∞)
WE ST TE
f (mm) 5.920 8.200 11.500
F _NO 3.58 4.16 5.00
ω (°) 32.2 24.0 17.4
d ₄ 6.60 3.56 1.30
d ₉ 6.76 8.69 11.46
d ₁₁ 1.23 1.22 1.23.

Example 3
r ₁ = 27.175 d ₁ = 1.20 n _d1 = 1.80610 ν _d1 = 40.74
r ₂ = 3.327 (aspherical surface) d ₂ = 1.60
r ₃ = 6.087 d ₃ = 1.70 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 12.927 d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = -0.20
r ₆ = 4.355 (aspherical surface) d ₆ = 1.80 n _d3 = 1.74330 ν _d3 = 49.33
r ₇ = 50.000 d ₇ = 0.85 n _d4 = 1.84666 ν _d4 = 23.78
r ₈ = 5.063 d ₈ = 2.75 n _d5 = 1.51633 ν _d5 = 64.14
r ₉ = -20.026 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.30 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₁ = ∞ d ₁₁ = (variable)
r ₁₂ = ∞ (image plane)
Aspheric coefficient 2nd surface K = -3.202
A ₄ = 8.94481 × 10 ^-3
A ₆ = -6.15065 × 10 ^-4
A ₈ = 4.52314 × 10 ^-5
A ₁₀ = -1.53842 × 10 ^-6
6th surface K = -4.132
A ₄ = 5.81884 × 10 ^-3
A ₆ = -4.01777 × 10 ^-4
A ₈ = 5.33499 × 10 ^-5
A ₁₀ = -4.58420 × 10 ^-6
A ₁₂ = -1.00000 × 10 ^-7
Surface 9 K = 0.000
A ₄ = 4.74901 × 10 ^-3
A ₆ = -8.09534 × 10 ^-5
A ₈ = 1.32302 × 10 ^-4
A ₁₀ = -8.52519 × 10 ^-6
Zoom data (∞)
WE ST TE
f (mm) 5.920 8.200 11.500
F _NO 3.58 4.16 5.00
ω (°) 32.1 23.9 17.4
d ₄ 6.60 3.56 1.30
d ₉ 6.57 8.45 11.18
d ₁₁ 1.23 1.22 1.21.

Example 4
r ₁ = 76.650 d ₁ = 1.20 n _d1 = 1.80610 ν _d1 = 40.92
r ₂ = 3.276 (aspherical surface) d ₂ = 1.40
r ₃ = 6.251 d ₃ = 1.70 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 16.782 d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = -0.20
r ₆ = 4.384 (aspherical surface) d ₆ = 2.30 n _d3 = 1.69350 ν _d3 = 53.21
r ₇ = 300.000 d ₇ = 0.80 n _d4 = 1.84666 ν _d4 = 23.78
r ₈ = 6.297 d ₈ = 2.40 n _d5 = 1.48749 ν _d5 = 70.23
r ₉ = -13.015 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.30 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₁ = ∞ d ₁₁ = (variable)
r ₁₂ = ∞ (image plane)
Aspheric coefficient 2nd surface K = -1.130
A ₄ = 1.83732 × 10 ^-3
A ₆ = -2.30469 × 10 ^-5
A ₈ = 4.01044 × 10 ^-6
A ₁₀ = -1.91354 × 10 ^-7
6th surface K = -0.345
A ₄ = -5.98870 × 10 ^-5
A ₆ = 6.13929 × 10 ^-6
A ₈ = -2.96420 × 10 ^-6
A ₁₀ = 8.00000 × 10 ^-7
Surface 9 K = 0.000
A ₄ = 4.16180 × 10 ^-3
A ₆ = 9.37500 × 10 ^-5
A ₈ = 6.17499 × 10 ^-5
A ₁₀ = 1.48794 × 10 ^-7
Zoom data (∞)
WE ST TE
f (mm) 5.923 7.997 11.492
F _NO 3.61 4.16 5.09
ω (°) 32.7 24.8 17.5
d ₄ 6.09 3.53 1.30
d ₉ 7.10 8.99 12.17
d ₁₁ 1.22 1.21 1.18.

Example 5
r ₁ = 114.165 d ₁ = 1.00 n _d1 = 1.80610 ν _d1 = 40.92
r ₂ = 3.318 (aspherical surface) d ₂ = 1.40
r ₃ = 6.530 d ₃ = 1.70 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 20.319 d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = -0.20
r ₆ = 4.040 (aspherical surface) d ₆ = 2.30 n _d3 = 1.58313 ν _d3 = 59.38
r ₇ = -927.117 d ₇ = 0.80 n _d4 = 1.84666 ν _d4 = 23.78
r ₈ = 7.532 d ₈ = 2.40 n _d5 = 1.48749 ν _d5 = 70.23
r ₉ = -11.782 (aspherical surface) d ₉ = (variable)
r ₁₀ = ∞ d ₁₀ = 1.30 n _d6 = 1.51633 ν _d6 = 64.14
r ₁₁ = ∞ d ₁₁ = (variable)
r ₁₂ = ∞ (image plane)
Aspheric coefficient 2nd surface K = -0.497
A ₄ = -5.19094 × 10 ^-4
A ₆ = -8.99866 × 10 ^-5
A ₈ = 3.08269 × 10 ^-6
A ₁₀ = -4.03659 × 10 ^-10
6th surface K = -1.345
A ₄ = 1.68161 × 10 ^-3
A ₆ = 7.65859 × 10 ^-5
A ₈ = -9.37869 × 10 ^-6
A ₁₀ = 8.94817 × 10 ^-7
Surface 9 K = 0.000
A ₄ = 3.57902 × 10 ^-3
A ₆ = 3.92389 × 10 ^-4
A ₈ = 2.36601 × 10 ^-6
A ₁₀ = 2.89859 × 10 ^-8
Zoom data (∞)
WE ST TE
f (mm) 5.904 7.997 11.498
F _NO 3.58 4.11 5.00
ω (°) 30.5 23.0 16.2
d ₄ 6.46 3.68 1.30
d ₉ 7.51 9.43 12.66
d ₁₁ 1.20 1.19 1.16.

Example 6
r ₁ = -125.182 d ₁ = 1.00 n _d1 = 1.80610 ν _d1 = 40.92
r ₂ = 3.312 (aspherical surface) d ₂ = 1.40
r ₃ = 7.062 d ₃ = 1.70 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 36.331 d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = -0.20
r ₆ = 4.057 (aspherical surface) d ₆ = 2.30 n _d3 = 1.58313 ν _d3 = 59.38
r ₇ = 100.000 d ₇ = 0.80 n _d4 = 1.84666 ν _d4 = 23.78
r ₈ = 6.615 d ₈ = 2.40 n _d5 = 1.48749 ν _d5 = 70.23
r ₉ = -13.364 (aspherical surface) d ₉ = (variable)
r ₁₀ = 50.000 d ₁₀ = 1.20 n _d6 = 1.48749 ν _d6 = 70.23
r ₁₁ = -50.000 d ₁₁ = (variable)
r ₁₂ = ∞ d ₁₂ = 1.30 n _d7 = 1.51633 ν _d7 = 64.14
r ₁₃ = ∞ d ₁₃ = (variable)
r ₁₄ = ∞ (image plane)
Aspheric coefficient 2nd surface K = -0.332
A ₄ = -1.50043 × 10 ^-3
A ₆ = -1.60862 × 10 ^-4
A ₈ = 3.25971 × 10 ^-6
A ₁₀ = 6.05120 × 10 ^-10
6th surface K = -1.287
A ₄ = 1.60279 × 10 ^-3
A ₆ = 7.70238 × 10 ^-5
A ₈ = -8.90829 × 10 ^-6
A ₁₀ = 8.95272 × 10 ^-7
Surface 9 K = 0.000
A ₄ = 3.47544 × 10 ^-3
A ₆ = 4.02997 × 10 ^-4
A ₈ = 3.07449 × 10 ^-6
A ₁₀ = 2.96993 × 10 ^-8
Zoom data (∞)
WE ST TE
f (mm) 5.905 7.995 11.496
F _NO 3.46 4.01 4.92
ω (°) 31.2 23.6 16.6
d ₄ 6.30 3.66 1.30
d ₉ 6.45 8.89 12.18
d ₁₁ 0.80 0.80 0.80
d ₁₃ 1.32 1.03 1.36.

Example 7
r ₁ = -413.848 d ₁ = 1.00 n _d1 = 1.80610 ν _d1 = 40.92
r ₂ = 3.317 (aspherical surface) d ₂ = 1.48
r ₃ = 7.388 d ₃ = 1.70 n _d2 = 1.84666 ν _d2 = 23.78
r ₄ = 43.892 d ₄ = (variable)
r ₅ = ∞ (aperture) d ₅ = -0.20
r ₆ = 4.055 (aspherical surface) d ₆ = 2.19 n _d3 = 1.58313 ν _d3 = 59.38
r ₇ = 100.000 d ₇ = 1.13 n _d4 = 1.84666 ν _d4 = 23.78
r ₈ = 6.376 d ₈ = 2.43 n _d5 = 1.48749 ν _d5 = 70.23
r ₉ = -15.930 (aspherical surface) d ₉ = (variable)
r ₁₀ = 44.301 d ₁₀ = 1.20 n _d6 = 1.48749 ν _d6 = 70.23
r ₁₁ = -44.574 d ₁₁ = (variable)
r ₁₂ = ∞ d ₁₂ = 1.30 n _d7 = 1.51633 ν _d7 = 64.14
r ₁₃ = ∞ d ₁₃ = (variable)
r ₁₄ = ∞ (image plane)
Aspheric coefficient 2nd surface K = -0.341
A ₄ = -1.57613 × 10 ^-3
A ₆ = -1.57295 × 10 ^-4
A ₈ = 3.25595 × 10 ^-6
A ₁₀ = 6.64658 × 10 ^-10
6th surface K = -1.258
A ₄ = 1.50474 × 10 ^-3
A ₆ = 7.67463 × 10 ^-5
A ₈ = -8.90504 × 10 ^-6
A ₁₀ = 8.95276 × 10 ^-7
Surface 9 K = 0.000
A ₄ = 3.48874 × 10 ^-3
A ₆ = 4.00153 × 10 ^-4
A ₈ = 3.07420 × 10 ^-6
A ₁₀ = 2.96881 × 10 ^-8
Zoom data (∞)
WE ST TE
f (mm) 5.902 7.994 11.498
F _NO 3.53 4.24 5.00
ω (°) 30.2 22.9 16.3
d ₄ 6.20 4.05 1.00
d ₉ 3.46 8.69 8.12
d ₁₁ 3.68 0.78 5.04
d ₁₃ 1.16 1.23 1.23.

  Aberration diagrams at the time of focusing on an object point at infinity in Examples 1 to 7 are shown in FIGS. In these aberration diagrams, (a) shows the spherical aberration, astigmatism, distortion and lateral chromatic aberration at the wide-angle end, (b) the intermediate state, and (c) the telephoto end. In each aberration diagram, “FIY” represents the image height.

Values excluding the absolute value symbols in the conditional expressions (1) to (6) of Examples 1 to 7 are as follows. Example (1) (2) (3) (4) (5) (6)
1 -25.641 0.31769 45.02 -1.629 1.281 1.949
2 6.410 0.31769 45.02 -1.481 1.246 1.942
3 6.410 0.33033 40.36 -1.499 1.231 1.943
4 38.462 0.36589 46.45 -1.359 1.228 1.940
5 -118.861 0.36589 46.45 -1.402 1.281 1.947
6 12.821 0.36589 46.45 -1.391 1.338 1.947
7 12.821 0.36589 46.45 -1.453 1.386 1.948.

  An example of an electronic photographing apparatus, particularly a digital camera, a video camera, and an information processing apparatus, which forms an object image with the zoom optical system according to the present invention as described above and receives the image with an image sensor such as a CCD. It can be used for certain personal computers, telephones, especially mobile phones that are convenient to carry. The embodiment is illustrated below.

  FIGS. 15 to 17 are conceptual diagrams of structures in which the zoom optical system according to the present invention is incorporated in the photographing optical system 41 of a digital camera. 15 is a front perspective view showing the appearance of the digital camera 40, FIG. 16 is a rear front view thereof, and FIG. 17 is a schematic perspective plan view showing the configuration of the digital camera 40. However, FIGS. 15 and 17 show a state in which the photographing optical system 41 is not retracted. In this example, the digital camera 40 includes a photographing optical system 41 having a photographing optical path 42, a finder optical system 43 having a finder optical path 44, a shutter button 45, a flash 46, a liquid crystal display monitor 47, a focal length change button 61, When the photographing optical system 41 is retracted, including the setting change switch 62, the photographing optical system 41, the finder optical system 43, and the flash 46 are covered with the cover 60 by sliding the cover 60. Then, when the cover 60 is opened and the camera 40 is set to the photographing state, the photographing optical system 41 enters the non-collapsed state of FIG. 17, and when the shutter button 45 disposed on the upper part of the camera 40 is pressed, the photographing is performed in conjunction therewith. Photographing is performed through the optical system 41, for example, the zoom optical system of the first embodiment. An object image formed by the photographing optical system 41 is formed on the imaging surface of the CCD 49 through a low-pass filter and a cover glass that have been subjected to IR cut coating. The object image received by the CCD 49 is displayed as an electronic image on the liquid crystal display monitor 47 provided on the back of the camera via the processing means 51. Further, the processing means 51 is connected to a recording means 52 so that a photographed electronic image can be recorded. The recording means 52 may be provided separately from the processing means 51, or may be configured to perform recording / writing electronically using a floppy disk, memory card, MO, or the like. Further, it may be configured as a silver salt camera in which a silver salt film is arranged in place of the CCD 49.

  Further, a finder objective optical system 53 is disposed on the finder optical path 44. The finder objective optical system 53 includes a plurality of lens groups (three groups in the figure) and two prisms, and includes a zoom optical system whose focal length changes in conjunction with the zoom optical system of the photographing optical system 41. The object image formed by the finder objective optical system 53 is formed on the field frame 57 of the erecting prism 55 which is an image erecting member. Behind the erecting prism 55, an eyepiece optical system 59 for guiding the erect image to the observer eyeball E is disposed. A cover member 50 is disposed on the exit side of the eyepiece optical system 59.

  In the digital camera 40 configured in this manner, the photographing optical system 41 has a high performance and a small size and can be retracted, so that a high performance and a small size can be realized.

  Next, a personal computer which is an example of an information processing apparatus in which the zoom optical system according to the present invention is incorporated as an objective optical system is shown in FIGS. 18 is a front perspective view with the cover of the personal computer 300 opened, FIG. 19 is a sectional view of the photographing optical system 303 of the personal computer 300, and FIG. 20 is a side view of the state of FIG. As shown in FIGS. 18 to 20, the personal computer 300 includes a keyboard 301 for the writer to input information from the outside, information processing means and recording means not shown, and a monitor for displaying information to the operator. 302 and a photographing optical system 303 for photographing the operator himself and surrounding images. Here, the monitor 302 may be a transmissive liquid crystal display element that is illuminated from the back by a backlight (not shown), a reflective liquid crystal display element that reflects and displays light from the front, a CRT display, or the like. Further, in the drawing, the photographing optical system 303 is built in the upper right of the monitor 302. However, the imaging optical system 303 is not limited to the place, and may be anywhere around the monitor 302 or the keyboard 301.

  The photographing optical system 303 includes an objective lens 112 including a zoom optical system (abbreviated in the drawing) according to the present invention and an image sensor chip 162 that receives an image on a photographing optical path 304. These are built in the personal computer 300.

  Here, an optical low-pass filter F is additionally attached on the image sensor chip 162 to be integrally formed as an image pickup unit 160, and can be fitted and attached to the rear end of the lens frame 113 of the objective lens 112 with one touch. Therefore, the center alignment of the objective lens 112 and the image sensor chip 162 and the adjustment of the surface interval are unnecessary, and the assembly is simple. A cover glass 114 for protecting the objective lens 112 is disposed at the tip of the lens frame 113. The driving mechanism of the zoom optical system in the lens frame 113 is not shown.

  The object image received by the image sensor chip 162 is input to the processing means of the personal computer 300 via the terminal 166 and displayed on the monitor 302 as an electronic image. FIG. A rendered image 305 is shown. The image 305 can also be displayed on the personal computer of the communication partner from a remote location via the processing means, the Internet, or the telephone.

  Next, FIG. 21 shows a telephone which is an example of an information processing apparatus in which the zoom optical system according to the present invention is incorporated as a photographing optical system, particularly a portable telephone which is convenient to carry. 21A is a front view of the mobile phone 400, FIG. 21B is a side view, and FIG. 21C is a cross-sectional view of the photographing optical system 405. As shown in FIGS. 21A to 21C, the mobile phone 400 includes a microphone unit 401 that inputs an operator's voice as information, a speaker unit 402 that outputs the voice of the other party, and an operator who receives information. An input dial 403 for inputting information, a monitor 404 for displaying information such as a photographed image and a telephone number of the operator and the other party, a photographing optical system 405, an antenna 406 for transmitting and receiving communication radio waves, and an image And processing means (not shown) for processing information, communication information, input signals, and the like. Here, the monitor 404 is a liquid crystal display element. In the drawing, the arrangement positions of the respective components are not particularly limited to these. The photographing optical system 405 includes an objective lens 112 that is a zoom optical system (abbreviated in the drawing) according to the present invention disposed on a photographing optical path 407 and an image sensor chip 162 that receives an object image. These are built in the mobile phone 400.

  Here, an optical low-pass filter F is additionally attached on the image sensor chip 162 to be integrally formed as an image pickup unit 160, and can be fitted and attached to the rear end of the lens frame 113 of the objective lens 112 with one touch. Therefore, the center alignment of the objective lens 112 and the image sensor chip 162 and the adjustment of the surface interval are unnecessary, and the assembly is simple. A cover glass 114 for protecting the objective lens 112 is disposed at the tip of the lens frame 113. The driving mechanism of the zoom optical system in the lens frame 113 is not shown.

  The object image received by the imaging element chip 162 is input to the processing means (not shown) via the terminal 166 and displayed as an electronic image on the monitor 404, the monitor of the communication partner, or both. . Further, when transmitting an image to a communication partner, the processing means includes a signal processing function for converting information of an object image received by the image sensor chip 162 into a signal that can be transmitted.

  In each embodiment, if a filter such as a low-pass filter is omitted, the camera thickness when retracted can be made thinner.

FIG. 2 is a lens cross-sectional view of the zoom optical system according to the first exemplary embodiment at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on an object point at infinity. FIG. 3 is a lens cross-sectional view similar to FIG. 1 of the zoom optical system of Example 2. FIG. 6 is a lens cross-sectional view similar to FIG. 1 of the zoom optical system of Example 3. FIG. 6 is a lens cross-sectional view similar to FIG. 1 of a zoom optical system according to Example 4. FIG. 6 is a lens cross-sectional view similar to FIG. 1 of a zoom optical system according to Example 5. FIG. 9 is a lens cross-sectional view similar to FIG. 1 of a zoom optical system according to Example 6. FIG. 10 is a lens cross-sectional view similar to FIG. 1 illustrating a zoom optical system according to a seventh embodiment. FIG. 6 is an aberration diagram for Example 1 upon focusing on an object point at infinity. FIG. 6 is an aberration diagram for Example 2 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 3 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 4 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 5 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 6 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 7 upon focusing on an object point at infinity. It is a front perspective view which shows the external appearance of the digital camera incorporating the zoom optical system by this invention. FIG. 16 is a rear perspective view of the digital camera of FIG. 15. It is sectional drawing of the digital camera of FIG. It is the front perspective view which opened the cover of the personal computer incorporating the zoom optical system by this invention as an objective optical system. It is sectional drawing of the imaging optical system of a personal computer. It is a side view of the state of FIG. FIG. 3 is a front view (a), a side view (b), and a sectional view (c) of the photographing optical system of a mobile phone incorporating the zoom optical system according to the present invention as an objective optical system.

Explanation of symbols

G1 ... 1st lens group G2 ... 2nd lens group G3 ... 3rd lens group S ... Aperture stop P ... Parallel plate I ... Image plane E ... Observer eyeball F ... Optical low pass filter 40 ... Digital camera 41 ... Shooting optical system 42 ... Optical path for photographing 43 ... Viewfinder optical system 44 ... Optical path for viewfinder 45 ... Shutter button 46 ... Flash 47 ... Liquid crystal display monitor 49 ... CCD
DESCRIPTION OF SYMBOLS 50 ... Cover member 51 ... Processing means 52 ... Recording means 53 ... Finder objective optical system 55 ... Erect prism 57 ... Field frame 59 ... Eyepiece optical system 60 ... Cover 61 ... Focal length change button 62 ... Setting change switch 112 ... Objective Lens 113 ... Mirror frame 114 ... Cover glass 160 ... Imaging unit 162 ... Imaging element chip 166 ... Terminal 300 ... PC 301 ... Keyboard 302 ... Monitor 303 ... Shooting optical system 304 ... Shooting optical path 305 ... Image 400 ... Mobile phone 401 ... Microphone unit 402 ... Speaker unit 403 ... Input dial 404 ... Monitor 405 ... Shooting optical system 406 ... Antenna 407 ... Shooting optical path

Claims (20)

An optical system including a cemented lens having a cemented surface on an optical axis, wherein the air contact surfaces on the light incident side and the light exit side of the cemented lens are aspheric surfaces, and at least one in the cemented lens. An optical system comprising a cemented lens, wherein the cemented surface satisfies the following conditions:
6.4 <| (r / R) | (1)
Here, r is the radius of curvature of the joint surface on the optical axis, and R is the maximum diameter of the joint surface. The optical system including the cemented lens according to claim 1, wherein the cemented lens includes a plurality of cemented surfaces. 3. The optical system having a cemented lens according to claim 2, wherein the number of lenses constituting the cemented lens is three. The optical system is an imaging optical system, and the imaging optical system is:
A positive lens group having positive refractive power including the cemented lens;
A negative lens group of negative refractive power located on the object side of the positive lens group with a variable interval at the time of zooming;
4. The cemented lens according to claim 1, further comprising an aperture stop disposed between an exit surface of the negative lens group and an exit surface of the positive lens group. 5. Optical system. In order from the object side to the image plane side, a first lens group having a negative refractive power and a first lens group having a positive refractive power located on the image plane side with respect to the first lens group across a variable interval upon zooming. Two lens groups,
The second lens group is composed of three lenses,
The most image side lens and the object side lens of the second lens group are configured as a cemented lens joined on a surface on the optical axis,
The cemented lens, wherein the refractive index n ₂₃ for the d-line of the lens closest to the image plane and the refractive index n ₂₂ for the d-line of the object-side lens cemented with the lens satisfy the following conditions: An optical system with
0.31 <| n ₂₂ −n ₂₃ | (2) The three lenses are a positive lens, a negative lens, and a positive lens in order from the object side, and a cemented surface that is an object side surface of the positive lens closest to the image plane is a refractive surface having a negative refractive power. An optical system comprising the cemented lens according to claim 5. In order from the object side to the image plane side, a first lens group having a negative refractive power and a first lens group having a positive refractive power located on the image plane side with respect to the first lens group across a variable interval upon zooming. Two lens groups,
The second lens group is composed of three lenses,
The most image side lens and the object side lens of the second lens group are configured as a cemented lens joined on a surface on the optical axis,
An aperture stop is disposed between the exit surface of the first lens group and the entrance surface of the cemented lens,
A cemented lens, wherein an Abbe number ν ₂₃ based on the d-line of the lens closest to the image plane and an Abbe number ν ₂₂ based on the d-line of the lens cemented with the lens satisfy the following conditions: Provided optical system.
40.3 <| ν ₂₂ −ν ₂₃ | (3) The optical system comprising the cemented lens according to claim 5, wherein the following conditional expression is satisfied.
−1.8 <f ₁ / f _w <−1.2 (4)
1.1 <f ₂ / f _w <1.5 (5)
1.7 < _ft / _fw <2.5 (6)
Where f ₁ is the focal length of the first lens group, f ₂ is the focal length of the second lens group, _fw is the focal length of the entire optical system at the wide angle end, and _ft is the entire optical system at the telephoto end. Is the focal length. The half of the number of air contact surfaces is an aspherical surface, and the conic coefficient K when the aspherical surface shape is approximated by the following equation (A) is 0 or less: An optical system comprising the cemented lens according to claim 8.
x = (y ² / r) / [1+ {1- (K + 1) (y / r) ² } ^1/2 ]
+ A ₄ y ⁴ + A ₆ y ⁶ + A ₈ y ⁸ + A ₁₀ y ¹⁰ (A)
In the aspherical shape, x is an optical axis with the light traveling direction being positive, y is a direction orthogonal to the optical axis, r is a paraxial radius of curvature, K is a conical coefficient, A ₄ , A ₆ , A ₈ and A ₁₀ are fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients, respectively. The first lens group is composed of two lenses, a negative lens and a positive lens, in order from the object side,
The second lens group is composed of three lenses of a positive lens, a negative lens, and a positive lens in order from the object side,
6. The apparatus according to claim 5, further comprising a third lens group including one positive lens on the image plane side of the second lens group with a variable interval, and the optical system is configured as a three-group zoom lens. An optical system comprising the cemented lens according to claim 9. The first lens group is composed of two lenses, a negative lens and a positive lens, in order from the object side,
The second lens group is composed of three lenses of a positive lens, a negative lens, and a positive lens in order from the object side,
10. The optical system having a cemented lens according to claim 5, wherein the optical system is configured as a two-group zoom lens. The first lens group is composed of two lenses in order from the object side: a negative lens having an absolute value of the image side curvature radius smaller than the absolute value of the object side curvature radius, and a positive meniscus lens having a concave surface facing the image side. ,
In order from the object side, the second lens group includes, in order from the object side, a positive lens in which the absolute value of the object side curvature radius is smaller than the absolute value of the image side curvature radius, and a negative lens in which the absolute value of the image side curvature radius is smaller than the absolute value of the object side curvature radius. 12. An optical system comprising a cemented lens according to claim 10, wherein the optical system comprises a positive lens having an object side curvature radius smaller than an absolute value of the image side curvature radius. 13. The optical system having a cemented lens according to claim 12, wherein a distance on the optical axis between the negative lens and the positive lens in the first lens group is 1.4 mm or more and 1.6 mm or less. 14. The optical system having a cemented lens according to claim 5, wherein three lenses of the second lens group are configured by a cemented triplet lens. 15. The optical system with a cemented lens according to claim 14, wherein the thickness of the cemented triplet lens on the optical axis is 6 mm or less. 16. The optical system having a cemented lens according to claim 15, wherein the thickness of the cemented triplet lens on the optical axis is 5.5 mm or less. The brightness stop is disposed immediately before the object side of the first junction triplet lens, and the ratio of the thickness of the junction triplet lens to the maximum diameter of the brightness stop is 1.4 or more. An optical system comprising the cemented lens according to any one of 16. An optical system including the cemented lens according to any one of claims 5 to 9, and an electronic image sensor for converting an optical image obtained by the optical system into an electric signal. Imaging device. 19. The imaging apparatus according to claim 18, wherein an incident angle of the principal ray at the maximum image height position at the wide-angle end of the optical system is 15 ° or more and less than 30 °. 20. The imaging apparatus according to claim 19, wherein an incident angle of the principal ray at the maximum image height position at the wide-angle end of the optical system is 16 ° or more.

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