JP2016191764A - Zoom lens and image capturing device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens that features reduced total lens length and a wider view angle and offers good optical performance with small field curvature and chromatic aberration, and to provide an image capturing device having the same.SOLUTION: A zoom lens comprises a negative first lens group and a positive second lens group in order from the object side, and is configured such that distance between the lens groups changes when zooming from the wide angle end to the telephoto end. The first lens group consists of a negative lens and a positive lens. A focal length f1p of the positive lens of the first lens group, a focal length fT of the entire system at the telephoto end, a refractive index N1p of the positive lens of the first lens group for the d-ray, and an Abbe number ν1p of the positive lens of the first lens group for the d-ray are appropriately set.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a zoom lens and an image pickup apparatus using the same, and is suitable for a video camera, a digital camera, and the like.

  2. Description of the Related Art In recent years, image pickup apparatuses such as video cameras and digital cameras that use solid-state image pickup devices have been reduced in size and functionality. For the optical system used therefor, a zoom lens having a small size, a wide angle and a high resolution is required.

  In order to meet such demands, various zoom lenses have been proposed in the past, and as disclosed in Patent Documents 1 and 2, the zoom lens can be downsized with a configuration in which a negative positive group precedes from the object side. Prior art that realizes is known.

  Patent Document 1 discloses a small zoom lens with a silver salt camera equivalent focal length of 29 mm and a zoom ratio of about 4.7 times, and Patent Document 2 discloses a small zoom lens with a silver salt camera equivalent focal length of 23 mm and a zoom ratio of about 4.0 times. Has been.

JP 2011-064933 JP JP 2012-053222 A

  In order to reduce the size and widen the zoom lens preceded by the negative positive group, it is mainly effective to shorten the focal length of the negative lens in the first lens group. However, simply shortening the focal length of the negative lens in one lens unit causes field curvature in the entire zoom range, and axial chromatic aberration is reduced, realizing a high-resolution zoom lens. Difficult to do.

  In order to correct the field curvature and axial chromatic aberration caused by shortening the focal length of the negative lens in one group, it is necessary to properly select the focal length and material of the positive lens in the first group. is there. In particular, in order to suppress the cancellation of chromatic aberration caused by shortening the focal length of the negative lens in the first group and the increase in Petzval sum in the negative direction, and to correct the above aberration, the positive lens in the first group has a low refractive index. It is effective to use a highly dispersive material and set the focal length appropriately.

  The embodiment of Patent Document 1 is small, and if it is attempted to widen the angle by shortening the focal length of the negative lens in the first group, it is difficult to correct the field curvature. Although the embodiment of Patent Document 2 can realize a small size and a wide angle, it cannot be said that sufficient chromatic aberration correction is realized at the telephoto end, and has a problem.

  Accordingly, an object of the present invention is to appropriately change the focal length and material of the positive lens used in the first lens group in the zoom lens configuration preceded by the negative positive group, thereby reducing the magnification while maintaining a small wide angle. It is an object of the present invention to provide a zoom lens having good optical performance in which field curvature and chromatic aberration are corrected over the entire area, and an imaging apparatus using the zoom lens.

In order to achieve the above object, the zoom lens of the present invention provides:
In order from the object side to the image side, in the zoom lens having a negative first lens group and a second lens group having a positive refractive power, and the distance between the lens groups changes during zooming from the wide-angle end to the telephoto end, The first lens group consists of a negative lens and a positive lens, the focal length of the positive lens of the first lens group is f1p, the focal length of the entire system at the telephoto end is fT, and the refractive index of the positive lens of the first lens group is The following conditional expression is satisfied, where N1p and the Abbe number of the positive lens in the first lens group are ν1p.

0.300 <f1p / ft <1.350 (1)
1.400 <N1p <1.800 (2)
5.0 <ν1p <22.5 (3)

  According to the present invention, in a zoom lens having a negative first lens group and a positive second lens group in order from the object side, the zoom lens is configured over the entire zooming range while achieving both a reduction in size and a wide angle. A zoom lens in which curvature of field and chromatic aberration are well corrected, and an imaging apparatus using the same are obtained.

Lens sectional view of Numerical Example 1 of the present invention Aberration diagram at the wide angle end according to Numerical Example 1 of the present invention. Aberration diagram at intermediate position of Numerical Example 1 of the present invention Aberration diagram at the telephoto end according to Numerical Example 1 of the present invention. Lens sectional view of Numerical Example 2 of the present invention Aberration diagram at the wide angle end according to Numerical Example 2 of the present invention. Aberration diagram at intermediate position of Numerical Example 2 of the present invention Aberration diagram at the telephoto end according to Numerical Example 2 of the present invention. Lens sectional view of Numerical Example 3 of the present invention Aberration diagram at the wide angle end according to Numerical Example 3 of the present invention. Aberration diagram at intermediate position of Numerical Example 3 of the present invention Aberration diagram at the telephoto end according to Numerical Example 3 of the present invention Lens sectional view of Numerical Example 4 of the present invention Aberration diagram at the wide angle end according to Numerical Example 4 of the present invention. Aberration diagram at intermediate position of Numerical Example 4 of the present invention Aberration diagram at the telephoto end according to Numerical Example 4 of the present invention. Lens sectional view of Numerical Example 5 of the present invention Aberration diagram at the wide-angle end according to Numerical Example 5 of the present invention Aberration diagram at intermediate position of Numerical Example 5 of the present invention Aberration diagram at the telephoto end according to Numerical Example 5 of the present invention. Lens sectional drawing of Numerical Example 6 of the present invention Aberration diagram at the wide angle end according to Numerical Example 6 of the present invention. Aberration diagram at intermediate position of Numerical Example 6 according to the present invention Aberration diagram at the telephoto end according to Numerical Example 6 of the present invention. Schematic diagram of imaging apparatus of the present invention

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to Embodiment 1 of the present invention. 2, 3 and 4 are aberration diagrams of the zoom lens of Example 1 at the wide-angle end, the intermediate zoom position, and the telephoto end (long focal length end), respectively. Example 1 is a zoom lens having a zoom ratio of 5.30 and an aperture ratio of about 3.00 to 7.10.

  FIG. 5 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to Embodiment 2 of the present invention. FIGS. 6, 7, and 8 are aberration diagrams of the zoom lens of Example 2 at the wide-angle end, the intermediate zoom position, and the telephoto end (long focal length end), respectively. Example 2 is a zoom lens having a zoom ratio of 6.57 and an aperture ratio of about 3.10 to 7.10.

  FIG. 9 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to Embodiment 3 of the present invention. 10, 11 and 12 are aberration diagrams of the zoom lens of Example 3 at the wide-angle end, the intermediate zoom position, and the telephoto end (long focal length end), respectively. The third embodiment is a zoom lens having a zoom ratio of 5.72 and an aperture ratio of about 3.10 to 7.10.

  FIG. 13 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to Embodiment 4 of the present invention. FIGS. 14, 15, and 16 are aberration diagrams of the zoom lens of Example 4 at the wide-angle end, the intermediate zoom position, and the telephoto end (long focal length end), respectively. Example 4 is a zoom lens having a zoom ratio of 5.72 and an aperture ratio of about 3.10 to 7.10.

  FIG. 17 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to Example 5 of the present invention. 18, 19 and 20 are aberration diagrams of the zoom lens of Example 5 at the wide-angle end, the intermediate zoom position, and the telephoto end (long focal length end), respectively. Example 5 is a zoom lens having a zoom ratio of 4.00 and an aperture ratio of about 3.10 to 6.22.

  FIG. 21 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to Example 6 of the present invention. 22, FIG. 23, and FIG. 24 are aberration diagrams of the zoom lens of Example 6 at the wide-angle end, the intermediate zoom position, and the telephoto end (long focal length end), respectively. Example 5 is a zoom lens having a zoom ratio of 6.19 and an aperture ratio of about 3.10 to 7.10.

  In the lens cross-sectional view, Li indicates the i-th lens group, and i indicates the order of the lens groups from the object side to the image side. SP is an F-number determining member (hereinafter referred to as “aperture stop”) that functions as an aperture stop that determines (limits) an open F-number (Fno) light beam. G is an optical block corresponding to an optical filter, a face plate, a crystal low-pass filter, an infrared cut filter, or the like. IP is an image plane, and when used as a photographing optical system of a video camera or a digital still camera, an imaging plane of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is placed. Further, when used as a photographing optical system for a silver salt film camera, a photosensitive surface corresponding to the film surface is provided.

  In the aberration diagrams, d and g represent the d-line and g-line, respectively, and ΔM and ΔS represent the meridional image surface and the sagittal image surface, respectively. On-axis and lateral chromatic aberration are represented by g-line.

  First, as a feature of the present invention, in order from the object side, there is a negative first lens unit L1, a positive second lens unit L2, and the first lens unit is composed of a negative lens L1n and a positive lens L1p. The lens preferably satisfies the following conditions.

0.300 <f1p / ft <1.350 (1)
1.400 <N1p <1.800 (2)
5.0 <ν1p <22.5 (3)
However, the focal length of the positive lens L1p of the first lens group is f1p, the refractive index of the d line is N1p, the Abbe number of the d line is ν1p, and the focal length of the entire system at the telephoto end is fT.

  In a zoom lens with two negative and positive lenses in the first lens unit L1, the Petzval sum increases in the negative direction when the focal length of the negative lens L1n in the first unit is shortened to reduce the size and wide angle. A field curvature in the over direction occurs over the entire magnification range. In order to suppress the increase in the Petzval sum in the negative direction and correct the field curvature, it is effective to lower the refractive index while increasing the refractive power of the positive lens L1p included in the first group.

  To correct axial chromatic aberration at the telephoto end when the focal length of the negative lens L1n in the first lens unit L1 is shortened, the positive lens L1p in the first lens unit should be made of a high dispersion material. Is effective.

  Conditional expression (1) defines the focal length of the positive lens L1p in the first lens group. If the upper limit is exceeded, the refractive power of the positive lens will be too weak, and therefore, there is a problem that axial chromatic aberration of the g-line occurs in the over direction at the telephoto end. When the lower limit is exceeded, the refractive power of the positive lens becomes too strong, and the problem is that field curvature occurs in the under direction over the entire zooming range.

  Conditional expression (2) defines the refractive index of the positive lens L1p in the first lens group. If the upper limit is exceeded, the problem is that field curvature occurs in the over direction over the entire zoom range. If the lower limit is exceeded, the refractive index of the positive lens will drop too much, and in order to obtain the desired focal length within the range of conditional expression (1), the curvature of the positive lens will be too tight, and the under direction will be at the wide-angle end. Another problem is that the lateral chromatic aberration of g line occurs.

  Conditional expression (3) defines the Abbe number of the positive lens L1p in the first lens group. When the upper limit is exceeded, the dispersion of the positive lens L1p becomes too small, and the refracting power of the positive lens L1p becomes too strong to cancel the chromatic aberration that occurs in the negative lens L1n in one group, and coma aberration at the telephoto end Is difficult to correct. When the lower limit is exceeded, it becomes a problem that lateral chromatic aberration of g line occurs in the over direction at the wide angle end.

  By satisfying the above conditions (1) to (3), a zoom lens having a good optical performance that corrects field curvature and chromatic aberration over the entire zoom range is achieved, which is a subject of the present invention, while being a small and wide angle. It becomes possible to do.

  Still more preferably, in order to increase the effect of the embodiment, it is preferable to set the ranges of conditional expressions (1) to (3) to the following ranges.

0.500 <f1p / ft <1.350 (1a)
1.500 <N1p <1.750 (2a)
5.0 <ν1p <22.0 (3a)
More preferably, the ranges of conditional expressions (1a) to (3a) are set to the following ranges.

0.800 <f1p / ft <1.200 (1b)
1.600 <N1p <1.740 (2b)
5.0 <ν1p <21.5 (3b)
Furthermore, it is preferable that the zoom lens of the present invention satisfies the following conditions.

1.200 <f1 / f2 <2.000 (4)
1.600 <| f1n / fw | <4.000 (5)
1.700 <N1n <2.500 (6)
5.0 <ν1n <50.0 (7)
However, the focal length of the first lens unit L1 is f1, the focal length of the second lens unit L2 is f2, the focal length of the entire system at the wide angle end is fw, the focal length of the negative lens L1n of the first lens unit is f1n, The refractive index for the d-line of the negative lens L1n of the first lens group is N1n, and the Abbe number for the d-line of the negative lens L1n of the first lens group is ν1n.

  Conditional expression (4) defines the relationship between the focal length of the first lens unit L1 and the focal length of the first lens unit L2. If the upper limit is exceeded, the focal length of the first lens unit L1 becomes too long with respect to the second lens unit L2, which causes a problem of under-field curvature in the entire zoom range. Further, since the bending action of the off-axis light beam of the first group becomes too weak at the wide angle end, the lens diameter of the first lens group is increased, and there is a problem in terms of miniaturization. If the lower limit is exceeded, the focal length of the first lens group will be too short, and there will be a problem that field curvature occurs in the over direction at the wide-angle end.

  Conditional expression (5) defines the relationship between the focal length of the negative lens L1n of the first lens unit and the focal length of the entire system at the wide angle end. If the upper limit is exceeded, the focal length of the negative lens L1n of the first lens group becomes too long, and the problem is that lateral chromatic aberration of g-line occurs in the under direction at the wide-angle end. If the lower limit is exceeded, the focal length of the negative lens L1n of the first lens group becomes too short, and the problem is that over-direction field curvature occurs over the entire zoom range.

  Conditional expression (6) defines the refractive index of the negative lens L1n of the first lens group. When the upper limit is exceeded, the problem is that field curvature occurs in the under direction over the entire zoom range. Exceeding the lower limit causes the refractive index of the negative lens L1n to decrease too much, so that the curvature becomes too tight when the focal length of the negative lens L1n is shortened, and coma aberration occurs at the telephoto end.

  Conditional expression (7) defines the Abbe number of the negative lens L1n in the first lens group. When the upper limit is exceeded, it becomes a problem that lateral chromatic aberration of g line occurs in the under direction at the wide-angle end. When the lower limit is exceeded, the negative lens becomes too dispersive, and the chromatic aberration that occurs in the first group cannot be canceled sufficiently, and the longitudinal chromatic aberration of the g-line occurs in the over direction at the telephoto end. .

  Examples of the material that satisfies the conditional expressions (2) and (3) include a resin material such as N-polyvinylcarbazole, and a resin mixture material obtained by dispersing inorganic nanoparticles such as ITO in the resin material.

Since the refractive index, dispersion, and shape of the material based on these resins change greatly with temperature change, it is necessary to have a zoom lens configuration that guarantees optical performance at the time of temperature change. In the present invention, after the second lens unit L2, a negative lens L2n using a resin or a resin mixture material that satisfies the following conditional expressions (8), (9), (10) is introduced, By canceling the change in optical characteristics when the temperature changes with the positive lens L1p in one lens group, the optical performance when the temperature changes is guaranteed.

0.250 <| f2n / f1p | <2.000 (8)
1.400 <N2n <1.800 (9)
5.0 <ν2n <30.0 (10)
However, the focal length of the negative lens L2n is f2n, the refractive index of the d-line is N2n, and the Abbe number is ν2n.

  Conditional expression (8) is an expression that predefines the ratio of the focal lengths of the negative lens L2n included in the first lens group after the positive lens L1p and the second lens group. When the upper limit is exceeded, the refractive power of the negative lens L2n becomes too strong for the positive lens L1p, and when the temperature changes, focus fluctuation occurs in the over direction, which becomes a problem. When the lower limit is exceeded, the refractive power of the negative lens L1n becomes too weak with respect to the positive lens L1p. In particular, fluctuations in the peripheral image plane in the under direction occur at the wide-angle end when the temperature changes.

  Conditional expression (9) defines the refractive index of the negative lens L2n. If the upper limit is exceeded, the refractive index of the negative lens L2n is too large, and the curvature of the negative lens L2n becomes too loose, which reduces the sensitivity of the wide-angle end focus to the surface of the negative lens L2n and causes a change in temperature. The focus variation of the positive lens L1p cannot be canceled sufficiently, and the focus variation occurs in the under direction at the wide angle end. If the lower limit is exceeded, the curvature of the negative lens L2n becomes too tight, which increases the sensitivity of the spherical aberration at the telephoto end to the surface of the negative lens L2n. The problem is that the spherical aberration fluctuation in the over direction becomes large at the end.

  Conditional expression (10) defines the Abbe number of the negative lens L2n. When the upper limit is exceeded, the dispersion of the negative lens L2n is too small, so the chromatic aberration variation of the positive lens L1p cannot be canceled sufficiently at the time of temperature change, and the chromatic aberration variation of magnification occurs in the over direction at the wide angle end. It becomes a problem. Exceeding the lower limit causes the dispersion of the negative lens L2n to be too large, and therefore, when the temperature changes, an over-direction g-line axial chromatic aberration variation occurs at the telephoto end.

  In Examples 2 to 6 of the present invention, in the second lens unit L2, in order to further correct the axial chromatic aberration generated in L2, a cemented lens including two lenses, a positive lens Lcep and a negative lens Lcen, is used. It is arranged. The positive lens Lcep and the negative lens Lcen of this cemented lens satisfy the following conditions.

20.0 <νcep-νcen <80.0 (11)
However, the Abbe number of the positive lens Lcep is νcen and the Abbe number of the negative lens Lcen is νcen.

Conditional expression (11) defines the Abbe number difference between the d-line of the positive lens Lcep and the negative lens Lcen of the cemented lens. If the upper limit is exceeded, the axial chromatic aberration of the g line on the over side at the telephoto end will increase. When the lower limit is exceeded, the Abbe number difference between the positive lens Lcep and the negative lens Lcen is too close. The problem is that correction of coma aberration occurs in the entire area.
More preferably, in order to increase the effect of the embodiment, it is preferable to set the ranges of conditional expressions (4) to (11) to the following ranges.

1.250 <f1 / f2 <2.000 (4a)
1.800 <| f1n / fw | <4.000 (5a)
1.750 <N1n <2.000 (6a)
20.0 <ν1n <50.0 (7a)
0.280 <| f2n / f1p | <1.500 (8a)
1.500 <N2n <1.750 (9a)
5.0 <ν2n <28.0 (10a)
30.0 <νcep-νcen <80.0 (11a)
Next, details of the configuration of the zoom lens of the present invention will be described.

  First, as a common item in each embodiment, the zoom lens of each embodiment has a lens so that the distance between the first lens unit L1 and the second lens unit L2 is narrowed at the telephoto end with respect to the wide angle end during zooming. The group is moving. Furthermore, the second lens unit L2 is located on the object side at the telephoto end compared to the wide-angle end. The first lens unit L1 moves along a locus convex toward the image side. The zooming action during zooming is realized mainly by the movement of the second lens unit L2. Correction of focus fluctuations associated with zooming is realized mainly by movement of the first lens group.

  The aperture stop SP is disposed closer to the object side than the second lens unit L2. By arranging the aperture stop SP in this way, the distance from the aperture stop SP to the first lens unit L1 can be reduced at the wide-angle end, so that the lens diameter of the first lens unit L1 can be reduced. it can.

  The first lens unit L1 includes a negative lens L1n having a concave surface facing the image side in order from the object side, and a positive lens L1p having a convex surface facing the object side, and achieves both a reduction in front lens diameter and chromatic aberration correction. . Furthermore, the negative lens L1n is made of a high refractive index material, and the positive lens L1p is made of a low refractive index material, so that when the first group is strengthened to reduce the size and widen the angle, the Petzval sum is prevented from increasing in the negative direction. The field curvature is corrected. In addition, the positive lens L1p is configured as a high dispersion material with a small Abbe number so as to take a sufficient difference from the Abbe number of the negative lens, and without increasing the refractive power, the axial chromatic aberration at the telephoto end and the wide angle end The lateral chromatic aberration is corrected.

As a material of the positive lens L1p satisfying the above characteristics, there is mainly a resin material such as N-polyvinylcarbazole. Alternatively, a resin mixture material in which inorganic nanoparticles such as ITO are dispersed in a resin material is applicable. Table 1 shows the dispersion characteristics of the resin material and inorganic nanoparticles used in the present invention. Table 2 shows materials and dispersion characteristics of the positive lens L1p used in this example. The dispersion characteristic N (λ) of the resin mixture material in which the nanoparticles are dispersed is calculated by the following equation derived from the Drude equation.
N (λ) = [1 + V {N nano (λ) 2 - 1} + (1-V) {N p (λ) 2 -1}] 1/2
Here, lambda is an arbitrary wavelength, N _nano the refractive index of the nanoparticles, N _p is the refractive index of the mixed resin material, V is a fraction of the total volume of the nanoparticles to the volume of the resin material.

  Further, by making the positive lens L1p an aspherical surface, the curvature of field and the astigmatism on the wide angle side are corrected well while achieving both a wide angle and a small size. The same effect can be obtained by providing an aspheric surface on the negative lens side.

  In each example, a negative lens L2n using a resin or a resin mixture material is introduced after the second lens group L2, and the change in optical characteristics at the time of temperature change with the positive lens L1p of the first lens group is cancelled. This guarantees the optical performance when the temperature changes.

  Next, features of each embodiment will be described.

  The first to third embodiments have a negative-positive-positive three-group configuration, and the correction of the focus variation due to the subject distance is performed by the first lens group L1 or the third lens group L3.

  The second lens unit L2 of Example 1 includes two lenses, a positive lens and a negative lens L2n. By taking a sufficient Abbe number difference between these positive and negative lenses, axial chromatic aberration in the entire zooming range is corrected without increasing the refractive power.

  The second lens unit L2 of Examples 2 and 3 is composed of one positive / negative cemented lens and two negative lenses L2n. By taking a sufficient Abbe number difference between the positive and negative lenses of the cemented lens, axial chromatic aberration in the entire zooming range is corrected without increasing the refractive power.

  The third lens unit L3 in Examples 1 to 3 includes one positive lens. When focusing is performed by the third lens unit L3, there is an advantage that quick focusing can be performed because the lens unit to be driven can be reduced in weight. Further, by using an aspherical surface for the positive lens of the third lens unit L3, the field curvature and astigmatism at the telephoto end are corrected well.

  The fourth embodiment has a four-group configuration that is positive, negative, positive, and positive. Correction of focus variation due to subject distance is performed by the first lens unit L1 or the third lens unit L3.

  The second lens unit L2 of Example 4 includes two lenses, that is, one positive / negative cemented lens and one negative lens L2n. By taking a sufficient Abbe number difference between the positive and negative lenses of the cemented lens, axial chromatic aberration in the entire zooming range is corrected without increasing the refractive power.

  The third lens unit L3 according to the fourth exemplary embodiment includes one positive lens. When focusing is performed by the third lens unit L3, there is an advantage that quick focusing can be performed because the lens unit to be driven can be reduced in weight. Further, by using an aspherical surface for the positive lens of the third lens unit L3, the field curvature and astigmatism at the telephoto end are corrected well.

  The fourth lens unit L4 according to the fourth exemplary embodiment includes one positive lens. By arranging the fourth lens group L4 in the vicinity of the solid-state image sensor, the fourth lens group L4 plays a role of suppressing the incident angle to the solid-state image sensor.

  The fifth embodiment has a negative and positive two-group configuration, and correction of the focus variation due to the subject distance is performed by the first lens group L1.

  The second lens unit L2 of Example 5 includes two lenses, that is, one positive / negative cemented lens and one negative lens L2n. By taking a sufficient Abbe number difference between the positive and negative lenses of the cemented lens, axial chromatic aberration in the entire zooming range is corrected without increasing the refractive power.

The sixth embodiment has a negative, positive, and negative four-group configuration, and correction of focus variation due to subject distance is performed by the first lens group L1, the third lens group L3, or the fourth lens group L4.
The second lens unit L2 of Example 6 includes one positive and negative cemented lens. By taking a sufficient Abbe number difference between the positive and negative lenses of the cemented lens, axial chromatic aberration in the entire zooming range is corrected without increasing the refractive power.

  In the third lens unit L3 of Example 6, the negative lens L2n is composed of only one lens, and during zooming, moves independently from the second lens unit L2, and at the telephoto end, by moving away from L2, The magnification is increased.

  The fourth lens unit L4 in Example 6 is composed of one positive lens. When focusing is performed by the fourth lens unit L4, there is an advantage that quick focusing can be performed because the lens unit to be driven can be reduced in weight. Further, by using an aspherical surface for the positive lens of the fourth lens unit L4, the field curvature and astigmatism at the telephoto end are corrected well.

  In each embodiment, camera shake correction can be performed by moving an arbitrary lens group in a direction perpendicular to the optical axis.

  Furthermore, the zoom lens proposed by the present invention can achieve higher performance in the entire zoom range by using it together with a system that corrects an electrical signal including distortion and lateral chromatic aberration by image processing.

  Next, numerical examples of the respective embodiments of the present invention will be shown. In each numerical example, i indicates the order of the surfaces from the object side, Ri is the radius of curvature of the lens surface, Di is the lens thickness and air spacing between the i-th surface and the i + 1-th surface, Ndi, νdi represents the refractive index and Abbe number for the d-line, respectively. The two surfaces closest to the image side are filter members such as a crystal low-pass filter and an infrared cut filter.

  The meanings of symbols used in each numerical example are as follows.

  In the numerical examples, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air spacing in order from the object side, and Ni and νi are the i-th lens in order from the object side. The refractive index and the Abbe number of the glass with respect to the d-line. Table 1 shows the relationship between the above-described conditional expressions and numerical examples.

  The aspheric shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, and A8 are the aspheric coefficients. When

It is expressed by the following formula. [E + X] means [× 10 + x], and [e-X] means [× 10-x]. An aspherical surface is indicated by adding * after the surface number.

[Numerical example 1]
Unit mm

Surface data surface number rd nd vd
1 -60.000 0.50 1.78590 44.2
2 8.267 1.40
3 * 11.122 2.00 1.69591 17.7
4 * 24.860 (d4)
5 (Aperture) ∞ -0.30
6 * 4.671 1.71 1.62263 58.2
7 * -13.687 0.30
8 * 5.814 1.00 1.63550 23.9
9 * 2.477 (d9)
10 * -115.726 1.65 1.53110 55.9
11 * -10.174 (d11)
12 ∞ 1.00 1.51633 64.1
13 ∞
Image plane ∞

Aspheric data 3rd surface
K = -1.17583e + 000 A 4 = -9.81933e-005 A 6 = -5.03160e-006 A 8 = -4.11267e-008 A10 = 9.16812e-010 A12 = 4.13756e-011
4th page
K = -9.54813e + 000 A 4 = -2.28315e-004 A 6 = -5.53779e-006 A 8 = -1.86540e-009 A10 = 3.43606e-010 A12 = 3.05805e-011
6th page
K = 1.54771e-001 A 4 = -4.04906e-004 A 6 = 3.70348e-005 A 8 = -1.10552e-005
7th page
K = -1.19407e + 001 A 4 = 1.77348e-003 A 6 = -2.01717e-004 A 8 = 3.83188e-006
8th page
K = -6.30272e + 000 A 4 = -2.22135e-003 A 6 = -1.21428e-004 A 8 = 1.30318e-005
9th page
K = -6.55071e-001 A 4 = -8.77728e-003 A 6 = 7.38091e-004 A 8 = -7.32192e-006

10th page
K = 5.05580e-004 A 4 = -7.59098e-005 A 6 = 6.04990e-007 A 8 = -2.65324e-008 A10 = -9.07371e-009
11th page
K = -2.61469e-001 A 4 = 7.97574e-005 A 6 = -1.61004e-006 A 8 = -1.04753e-007 A10 = -4.04619e-009

Various data Zoom ratio 5.30

Focal length 5.03 15.52 26.64
F number 3.00 5.60 7.10
Angle of view 30.83 14.02 7.49
Total lens length 37.82 32.16 38.95
BF 0.31 0.31 0.31
d 4 20.01 4.43 1.30
d 9 4.36 14.74 25.13
d11 3.88 3.42 2.95

Zoom lens group data group Start surface Focal length
1 1 -14.34
2 5 10.60
3 10 20.89

Single lens Data lens Start surface Focal length
1 1 -9.22
2 3 27.29
3 6 5.80
4 8 -7.69
5 10 20.89


[Numerical example 2]
Unit mm
Surface data surface number rd nd vd
1 -486.282 0.50 1.80 400 46.6
2 7.465 1.88
3 * 9.600 1.80 1.70433 15.5
4 * 15.285 (d4)
5 (Aperture) ∞ -0.30
6 * 6.644 2.20 1.76802 49.2
7 -11.318 1.00 1.92286 18.9
8 -18.442 0.28
9 * 6.258 1.00 1.63550 23.9
10 * 3.203 (d10)
11 * -23.272 1.65 1.53110 55.9
12 * -7.970 (d12)
13 ∞ 1.00 1.51633 64.1
14 ∞
Image plane ∞

Aspheric data 3rd surface
K = -6.90323e-001 A 4 = -1.29571e-004 A 6 = -1.45685e-006 A 8 = -2.37513e-008 A10 = 3.19287e-010 A12 = 7.14197e-011
4th page
K = -6.35894e + 000 A 4 = -1.24093e-004 A 6 = -3.08168e-006 A 8 = -3.89277e-008 A10 = 1.32092e-009 A12 = 5.44551e-011
6th page
K = -9.29547e-002 A 4 = -2.32813e-004 A 6 = -1.50225e-005 A 8 = -1.23132e-007
9th page
K = -1.85796e + 000 A 4 = -2.91853e-003 A 6 = 1.54609e-004 A 8 = -2.32766e-006
10th page
K = -1.49580e-001 A 4 = -5.34622e-003 A 6 = 1.98874e-004 A 8 = -1.85765e-005
11th page
K = -2.63208e + 001 A 4 = 1.28624e-005 A 6 = -8.33149e-005 A 8 = 7.87746e-006 A10 = -2.82986e-007
12th page
K = -2.38190e + 000 A 4 = 2.82219e-004 A 6 = -9.47334e-005 A 8 = 7.31629e-006 A10 = -2.28811e-007

Various data Zoom ratio 6.57

Focal length 4.76 17.31 31.25
F number 3.10 5.00 7.10
Angle of view 33.93 12.62 7.07
Image height 3.20 3.88 3.88
Total lens length 38.11 34.98 44.74
BF 0.31 0.31 0.31
d 4 18.82 3.28 0.63
d10 3.63 16.96 30.28
d12 4.35 3.43 2.52

Zoom lens group data group Start surface Focal length
1 1 -12.90
2 5 10.30
3 11 22.00

Single lens Data lens Start surface Focal length
1 1 -9.14
2 3 32.41
3 6 5.76
4 7 -34.04
5 9 -11.83
6 11 22.00


[Numeric Example 3]
Unit mm
Surface data surface number rd nd vd
1 -112.378 0.50 1.77250 49.6
2 7.316 1.65
3 * 11.400 2.30 1.63465 21.0
4 * 32.128 (d4)
5 (Aperture) ∞ -0.30
6 * 8.122 2.20 1.76802 49.2
7 -10.568 1.00 1.92286 18.9
8 -17.453 0.28
9 * 4.725 1.00 1.63550 23.9
10 * 2.899 (d10)
11 * 362.364 1.65 1.53110 55.9
12 * -12.054 (d12)
13 ∞ 1.00 1.51633 64.1
14 ∞
Image plane ∞

Aspheric data 3rd surface
K = -2.17475e-001 A 4 = -1.47189e-005 A 6 = -3.32394e-006 A 8 = 4.08635e-008 A10 = -1.44736e-010 A12 = 5.74362e-011
4th page
K = -7.21285e + 000 A 4 = -1.93352e-004 A 6 = -3.61926e-006 A 8 = -5.55168e-008 A10 = 3.89750e-009 A12 = -3.45233e-011
6th page
K = -2.65899e-001 A 4 = -3.48171e-004 A 6 = -1.54283e-005 A 8 = 2.51562e-007
9th page
K = -6.35458e-001 A 4 = -2.01758e-003 A 6 = 1.14562e-004 A 8 = -1.12410e-006
10th page
K = -3.81400e-001 A 4 = -3.96137e-003 A 6 = 1.20940e-004 A 8 = -1.15466e-005
11th page
K = -5.38312e + 005 A 4 = 2.19529e-004 A 6 = -8.76682e-006 A 8 = 1.03777e-006 A10 = -4.15660e-008
12th page
K = -2.30537e + 000 A 4 = 1.43604e-004 A 6 = 8.50550e-007 A 8 = 4.17761e-007 A10 = -2.84768e-008

Various data Zoom ratio 5.72

Focal length 4.80 15.81 27.46
F number 3.10 5.00 7.10
Angle of view 33.69 13.78 8.03
Total lens length 41.61 35.53 43.57
BF 0.30 0.30 0.30
d 4 21.19 3.85 0.63
d10 4.78 16.52 28.27
d12 4.05 3.57 3.09

Zoom lens group data group Start surface Focal length
1 1 -14.03
2 5 11.20
3 11 22.00

Single lens Data lens Start surface Focal length
1 1 -8.88
2 3 26.69
3 6 6.30
4 7 -31.20
5 9 -15.00
6 11 22.00


[Numeric Example 4]
Unit mm

Surface data surface number rd nd vd
1 -118.688 0.50 1.76802 49.2
2 7.378 1.83
3 * 12.078 2.30 1.63465 21.0
4 * 34.362 (d4)
5 (Aperture) ∞ -0.30
6 * 8.074 2.20 1.76802 49.2
7 -10.643 1.00 1.92286 18.9
8 -17.443 0.28
9 * 4.535 1.00 1.63550 23.9
10 * 2.785 (d10)
11 * 870.110 1.65 1.53110 55.9
12 * -12.149 (d12)
13 * -10.000 1.30 1.53110 55.9
14 * -9.000 1.83
15 ∞ 1.00 1.51633 64.1
16 ∞
Image plane ∞

Aspheric data 3rd surface
K = -2.63584e-001 A 4 = -1.96612e-005 A 6 = -3.39300e-006 A 8 = 3.68668e-008 A10 = -2.27820e-010 A12 = 5.43821e-011
4th page
K = -7.74434e + 000 A 4 = -1.94921e-004 A 6 = -3.72641e-006 A 8 = -5.95520e-008 A10 = 3.78729e-009 A12 = -3.19550e-011
6th page
K = -3.20963e-001 A 4 = -3.53660e-004 A 6 = -1.44675e-005 A 8 = 2.70872e-007
9th page
K = -6.40697e-001 A 4 = -2.02400e-003 A 6 = 1.03015e-004 A 8 = -8.42547e-007
10th page
K = -4.03813e-001 A 4 = -4.10570e-003 A 6 = 1.02588e-004 A 8 = -1.34699e-005
11th page
K = -8.13782e + 008 A 4 = 2.19221e-004 A 6 = -1.63224e-005 A 8 = 1.24883e-006 A10 = -5.22094e-008
12th page
K = -3.49561e + 000 A 4 = 1.70646e-004 A 6 = -2.08821e-005 A 8 = 9.33984e-007 A10 = -4.53327e-008
Side 13
K = 9.17902e-004 A 4 = 1.19517e-005 A 6 = -1.32441e-006 A 8 = -2.58300e-007 A10 = -2.80274e-009
14th page
K = -3.06575e-001 A 4 = 7.32257e-005 A 6 = 1.23938e-006 A 8 = 1.11112e-007 A10 = -5.72201e-009

Various data Zoom ratio 5.72

Focal length 4.82 15.88 27.59
F number 3.10 5.00 7.10
Angle of view 33.56 13.71 7.99
Total lens length 42.82 35.91 43.54
BF 0.31 0.31 0.31
d 4 21.69 3.83 0.52
d10 4.64 16.08 27.52
d12 1.59 1.09 0.59

Zoom lens group data group Start surface Focal length
1 1 -14.10
2 5 11.20
3 11 22.57
4 13 116.79

Single lens Data lens Start surface Focal length
1 1 -9.03
2 3 28.21
3 6 6.30
4 7 -31.83
5 9 -14.59
6 11 22.57
7 13 116.79


[Numerical example 5]
Unit mm
Surface data surface number rd nd vd
1 84.965 0.50 1.85000 40.0
2 7.179 1.82
3 * 11.200 2.30 1.63761 20.0
4 * 30.000 (d4)
5 (Aperture) ∞ -0.30
6 * 9.910 2.20 1.76802 49.2
7 -9.171 1.00 1.92286 18.9
8 -19.001 0.28
9 * 4.716 1.00 1.63550 23.9
10 * 3.631 (d10)
11 ∞ 1.00 1.51633 64.1
12 ∞
Image plane ∞

Aspheric data 3rd surface
K = -1.09578e + 000 A 4 = 7.23039e-006 A 6 = -5.59510e-006 A 8 = -1.12670e-008 A10 = 1.27868e-010 A12 = 1.19538e-010
4th page
K = -4.91141e + 000 A 4 = -1.86562e-004 A 6 = -7.85610e-006 A 8 = -3.66969e-008 A10 = 4.31517e-009 A12 = -2.28135e-012

6th page
K = -1.50683e + 000 A 4 = -6.41482e-004 A 6 = 1.00694e-005 A 8 = 2.14098e-007
9th page
K = -7.03877e-002 A 4 = 3.50322e-003 A 6 = 3.67687e-005 A 8 = 1.39010e-005
10th page
K = 7.55383e-001 A 4 = 1.86777e-003 A 6 = -1.12014e-007 A 8 = -5.61807e-006

Various data Zoom ratio 4.00

Focal length 5.11 12.78 20.46
F number 3.10 4.66 6.22
Angle of View 32.04 16.86 10.73
Total lens length 44.63 31.34 32.10
BF 0.30 0.30 0.30
d 4 24.32 5.59 0.91
d10 10.20 15.65 21.09

Zoom lens group data group Start surface Focal length
1 1 -15.00
2 5 10.64

Single lens Data lens Start surface Focal length
1 1 -9.25
2 3 26.76
3 6 6.53
4 7 -20.19
5 9 -38.70


[Numerical example 6]
Unit mm
Surface data surface number rd nd vd
1 -127.322 0.50 1.76802 49.2
2 7.808 1.64
3 * 12.100 2.30 1.64616 18.9
4 * 27.101 (d4)
5 (Aperture) ∞ -0.30
6 * 7.902 2.20 1.76802 49.2
7 -12.205 1.00 1.92286 18.9
8 -21.443 (d8)
9 * 4.964 1.00 1.63550 23.9
10 * 3.077 (d10)
11 * 673.531 1.65 1.53110 55.9
12 * -11.880 (d12)
13 ∞ 1.00 1.51633 64.1
14 ∞
Image plane ∞

Aspheric data 3rd surface
K = -5.26430e-001 A 4 = -4.33728e-005 A 6 = -3.22554e-006 A 8 = 3.04772e-008 A10 = -1.70073e-010 A12 = 4.86657e-011
4th page
K = -5.28246e + 000 A 4 = -1.88854e-004 A 6 = -3.75750e-006 A 8 = -4.49425e-008 A10 = 3.76478e-009 A12 = -2.89873e-011
6th page
K = -5.38088e-002 A 4 = -2.91492e-004 A 6 = -1.40193e-005 A 8 = 2.68564e-007
9th page
K = -4.99244e-001 A 4 = -1.80217e-003 A 6 = 8.64093e-005 A 8 = -8.56918e-007
10th page
K = -2.70870e-001 A 4 = -3.42817e-003 A 6 = 7.24391e-005 A 8 = -1.03078e-005
11th page
K = -8.88117e + 007 A 4 = -4.21347e-005 A 6 = 7.69641e-006 A 8 = 8.31846e-007 A10 = -9.53434e-009
12th page
K = -7.80254e-001 A 4 = 5.98058e-005 A 6 = 9.42622e-006 A 8 = 5.22266e-007 A10 = 3.08219e-009

Various data Zoom ratio 6.19

Focal length 4.85 16.90 30.00
F number 3.10 5.00 7.10
Angle of view 33.42 12.91 7.36
Total lens length 43.51 36.97 45.66
BF 0.30 0.30 0.30

d 4 22.57 3.98 0.63
d 8 0.17 0.40 0.62
d10 5.55 17.78 30.01
d12 3.92 3.52 3.11

Zoom lens group data group Start surface Focal length
1 1 -14.03
2 5 8.20
3 9 -16.04
4 11 22.00

Single lens Data lens Start surface Focal length
1 1 -9.56
2 3 31.91
3 6 6.56
4 7 -32.38
5 9 -16.04
6 11 22.00


Table 1 shows the dispersion characteristics of the resin material and inorganic nanoparticles used in the present invention. Table 2 shows materials and dispersion characteristics of the positive lens L1p used in the examples of the present invention. However, the resin material and the resin mixed material that can be used in the present invention are not limited to those in Table 2, and may be any material that satisfies the conditions.

Table 3 shows the relationship between the above-described conditional expressions and various numerical values in the numerical examples.

  Next, an embodiment of a digital camera (optical apparatus) using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG. In FIG. 25, 20 is a digital camera body, 21 is a photographing optical system constituted by the zoom lens of the above-described embodiment, 22 is an image sensor such as a CCD that receives a subject image by the photographing optical system 21, and 23 is an image sensor 22. A recording means 24 for recording the received subject image, and a viewfinder 24 for observing the subject image displayed on a display element (not shown).

  The display element is composed of a liquid crystal panel or the like, and a subject image formed on the image sensor 22 is displayed. Reference numeral 25 denotes a liquid crystal display panel having a function equivalent to that of the finder.

  Thus, by applying the zoom lens of the present invention to an optical apparatus such as a digital camera, an optical apparatus having a small size and high optical performance is realized.

Li i-th lens group, SP F number determining member, G optical block,
IP image plane

Claims (9)

In order from the object side to the image side, it has a negative first lens group, a second lens group of positive refractive power,
When zooming from the wide-angle end to the telephoto end, the zoom lens in which the distance between each lens group changes
The first lens group is composed of a negative lens and a positive lens in order from the object side to the image side, the focal length of the positive lens of the first lens group is f1p, the focal length of the entire system at the telephoto end is fT, and the first lens A zoom lens satisfying the following conditional expression, where N1p is the refractive index of the positive lens in the group and d is the Abbe number of the positive lens in the first lens group.
0.300 <f1p / ft <1.350
1.400 <N1p <1.800
5.0 <ν1p <22.5 2. The zoom lens according to claim 1, wherein when the focal length of the first lens group is f1, and the focal length of the second lens group is f2, the following is satisfied.
1.200 <| f1 / f2 | <2.000 3. The zoom lens according to claim 1, wherein when the focal length of the negative lens of the first lens group is f1n and the focal length of the entire system at the telephoto end is fw, the following is satisfied.
1.600 <| f1n / fw | <4.000 The following condition is satisfied, where N1n is the refractive index of the negative lens of the first lens group for the d-line and v1n is the Abbe number for the d-line. The zoom lens according to item.
1.700 <Nd1n <2.500
5.0 <νd1n <50.0 5. The zoom lens according to claim 1, wherein at least one negative lens satisfying the following condition is included after the second lens group. 6.
0.250 <| f2n / f1p | <2.000
1.400 <N2n <1.800
5.0 <ν2n <30.0
Where f2n is the focal length of the negative lens included after the second lens group.
N2n is the refractive index with respect to the d-line of the negative lens included after the second lens group
v2n is an Abbe number with respect to the d-line of the negative lens included after the second lens group.   6. The second lens group according to claim 1, wherein the second lens group includes a positive lens and a negative lens, and includes at least one cemented lens having a positive refractive power as a whole. The zoom lens according to item. 7. The zoom lens according to claim 6, wherein when the Abbe number of the positive lens of the cemented lens included in the second lens group is ν cep and the Abbe number of the negative lens is ν cen, the following condition is satisfied. .
20.0 <νdcep-νdcen <80.0   The zoom lens according to any one of claims 1 to 7, wherein the second lens group includes three or less lenses.   An imaging apparatus comprising the zoom lens according to any one of claims 1 to 8.