JP2007108398A - Zoom lens and imaging apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a zoom lens capable of satisfactorily correcting aberration including chromatic aberration all over the zoom area and having high optical performance. <P>SOLUTION: The zoom lens comprises a first lens group L1 having positive refractive power, a second lens group L2 having negative refractive power and a rear group having positive refractive power as a whole in order from an object side to an image side, and performs zooming by changing the spacing between the first lens group and the second lens group and the spacing between the second lens group and the rear group. The second lens group comprises three negative lenses and two positive lenses. When the Abbe number of the material of the positive lens having the highest positive refractive power in the second lens group and the partial dispersion ratio are respectively defined as νd, θgF, the zoom lens satisfies the conditions 30<νd, θgF<-1.79x10<SP>-3</SP>xνd+0.654. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a zoom lens and an image pickup apparatus having the same, and is suitable for an image pickup apparatus such as a digital camera, a video camera, and a silver salt film camera.

  In recent years, an image sensor used in an image pickup apparatus such as a digital camera has been increased in the number of pixels. Correspondingly, an imaging lens (imaging optical system) used in an imaging apparatus having an imaging element with a high pixel is required to be a zoom lens with high resolution and high zoom ratio.

  In order to be a high-resolution zoom lens, it is necessary that various aberrations relating to image performance in a single color (single wavelength) such as spherical aberration and coma are well corrected. In addition, it is necessary that the chromatic aberration be sufficiently corrected so that the image obtained when white illumination light is used does not have color blur.

  In addition, a zoom lens with a high zoom ratio is necessary for enlarging the photographing area.

  In general, in order to achieve a high zoom ratio, if the focal length at the zoom position at the telephoto end is made longer, a large amount of chromatic aberration of magnification occurs at the zoom position on the wide-angle side, and chromatic aberration of magnification at the zoom position on the telephoto side. In addition, a lot of longitudinal chromatic aberration occurs. For this reason, it is important to correct not only the temporary spectrum but also the secondary spectrum as chromatic aberration in order to obtain high-quality image performance.

  In general, in a photographic optical system, the shorter the total lens length (the distance from the first surface to the image surface, also referred to as the optical total length), the more chromatic aberrations such as axial chromatic aberration and lateral chromatic aberration occur, and the optical performance deteriorates.

  In particular, in a telephoto type (telephoto type) optical system, the chromatic aberration increases as the focal length increases, and the chromatic aberration increases as the total lens length decreases.

  As a method for reducing the occurrence of such chromatic aberration, an achromatic method using an abnormal partial dispersion material is generally well known.

  As a telephoto type zoom lens, a glass having anomalous dispersion is used in a zoom lens having a four-group configuration including positive, negative, positive, and positive refractive power lens groups in order from the object side to the image side. In this case, chromatic aberration is corrected (Patent Documents 1 and 2).

Further, in order from the object side to the embodiment, there is known a zoom lens in which chromatic aberration is corrected using a lens made of glass having anomalous dispersion, which is composed of a lens group having positive, negative, positive, negative, and positive refractive power. (Patent Documents 3 to 5).
JP 2000-32499 A JP-A-8-248317 JP 2001-350093 A Japanese Patent Laid-Open No. 2002-62478 JP 2001-194590 A

  In order to obtain a high-resolution image in a digital camera, a video camera, or the like, it is necessary to have a zoom lens that sufficiently corrects chromatic aberration that affects the color blur and the resolution of an image under illumination of white light.

  In particular, it is necessary to be a zoom lens in which lateral chromatic aberration is well corrected on the wide angle side.

  Glass having a large anomalous dispersion characteristic such as fluorite used for chromatic aberration correction generally has a low refractive index. Therefore, in order to correct a desired secondary spectrum using these glass materials in a zoom lens, it is necessary to appropriately set the lens configuration and lens material in each lens group.

  For example, in an optical system using low-dispersion glass with a large Abbe number such as fluorite, chromatic aberration does not change unless the refractive power of the lens surface is significantly changed. For this reason, a zoom lens with a high zoom ratio needs to have a lens configuration that can correct chromatic aberration and correct various aberrations such as spherical aberration, coma aberration, and astigmatism in a well-balanced manner in the entire zoom range.

  An object of the present invention is to provide a zoom lens having high optical performance and an image pickup apparatus having the same, which can satisfactorily correct chromatic aberration, in particular, various aberrations including a secondary spectrum of lateral chromatic aberration over the entire zoom range. To do.

The zoom lens of the present invention is
In order from the object side to the image side, the first lens group having a positive refractive power, a second lens group having a negative refractive power, and a rear group having a positive refractive power as a whole. In a zoom lens that performs zooming by changing the distance between the two lens groups and the distance between the second lens group and the rear group, the second lens group has three negative lenses and two positive lenses. When the Abbe number and partial dispersion ratio of the positive lens material having the most positive refractive power in the two lens groups are νd and θgF, respectively,
30 <νd
θgF <−1.79 × 10 ⁻³ · νd +0.654
It is characterized by satisfying the following conditions.

In order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, In the zoom lens in which each lens unit moves so that the air space between each lens unit changes during zooming from the wide-angle end to the telephoto end, i is set from the object side. The order when counting toward the image side is shown. When the air distance between the i-th lens group and the i + 1-th lens group at the wide-angle end and the telephoto end is Diw, Dit, and the focal length of the i-th lens group is fi,
D1w <D1t
D2w> D2t
D3w <D3t
D4w> D4t
1.5 <f3 / | f2 | <2.5
2 <| f4 / f2 | <3.5
2 <f5 / | f2 | <5
It is characterized by satisfying the following conditions.

  According to the present invention, it is possible to satisfactorily correct chromatic aberration, in particular, various aberrations including a secondary spectrum of lateral chromatic aberration over the entire zoom range, and a zoom lens having high optical performance and an imaging apparatus having the same can be obtained. .

  Hereinafter, the zoom lens of the present invention and an image pickup apparatus having the same will be described.

  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. FIGS. 2 and 3 are a wide-angle end and a telephoto end (long focal length end) of the zoom lens according to Embodiment 1, respectively. FIG.

  FIG. 4 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 2 of the present invention, and FIGS. 5 and 6 are aberration diagrams at the wide-angle end and telephoto end of the zoom lens according to Embodiment 2, respectively.

  FIG. 7 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 3 of the present invention, and FIGS. 8 and 9 are aberration diagrams at the wide-angle end and telephoto end of the zoom lens according to Embodiment 3, respectively.

  FIG. 10 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 4 of the present invention. FIGS. 11 and 12 are aberration diagrams at the wide-angle end and telephoto end of the zoom lens according to Embodiment 4, respectively.

  FIG. 13 is a schematic diagram of a main part of the imaging apparatus of the present invention.

  The zoom lens of the present invention is used in an imaging apparatus such as a digital camera, a video camera, a silver salt film camera, an optical apparatus such as a telescope, a binocular observation apparatus, a copying machine, and a projector.

  In the lens cross-sectional views shown in FIGS. 1, 4, 7, and 10, the left side is the front (object side, enlargement side), and the right side is the rear (image side, reduction side).

  i indicates the order when counted from the object side, and Li is the i-th lens group.

  The zoom lens according to each of the embodiments includes, in order from the object side to the image side, a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, and a plurality of lens units. It consists of the rear group LR. Then, zooming is performed by changing the interval between the first lens unit L1 and the second lens unit L2 and the interval between the second lens unit L2 and the rear unit LR.

  In each embodiment, the rear group LR includes a third lens unit L3 having a positive refractive power, a fourth lens unit L4 having a negative refractive power, and a fifth lens unit L5 having a positive refractive power.

  P2A and P2B are positive lenses. L4a and L4b are lens groups having negative refractive power.

  Reference numeral SP denotes an aperture stop, which is disposed in the third lens unit L3 in each embodiment.

  SSP is a flare-cut stop, which is disposed on the object side of the third lens unit L3 in each embodiment.

  IP is an image plane, and when used as a photographing optical system of a video camera or a digital still camera, a photosensitive surface corresponding to an imaging surface of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is placed.

  In the aberration diagrams, d, g, C, and F are d-line, g-line, C-line, and F-line, respectively. S · C is a sine condition. ΔdM and ΔdS are the d-line meridional image plane and sagittal image plane, and ΔgM and ΔgS are the g-line meridional image plane and sagittal image plane. fno is an F number, and ω is a half angle of view.

  In each embodiment, each lens group is moved as indicated by an arrow during zooming from the wide-angle end to the telephoto end.

  Specifically, during zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves to the object side, the second lens unit L2 moves to the image side, the third lens unit L3, the fourth lens unit L4, and the fifth lens. The group L5 moves to the object side while changing the air gap between the lens groups.

  In each embodiment, the wide-angle end and the telephoto end are zoom positions when the zoom lens unit is positioned at both ends of a range in which the zoom lens group can move on the optical axis.

  Next, features of each embodiment will be described.

  The second lens unit L2 has three negative lenses and two positive lenses. The Abbe number and partial dispersion ratio of the material of the positive lens P2A having the strongest positive refractive power in the second lens unit L2 are set to νd and θgF, respectively.

At this time,
30 <νd (1)
θgF <−1.79 × 10 ⁻³ · νd + 0.654 (2)
Is satisfied.

  Here, the Abbe number νd and the partial dispersion ratio θgF of the optical member are as follows.

Now, let the refractive indexes of the Fraunhofer lines for the g-line, F-line, d-line, and C-line be N _g , N _F , N _d and N _C , respectively. At this time, the Abbe number νd and the partial dispersion ratio θgF are νd = (N _d −1) / (N _F −N _C ).
It is represented by

  Conventionally, a zoom lens having a high zoom ratio including a wide-angle region has a four-group configuration including, in order from the object side, a lens group having positive, negative, positive, and positive refractive power, and positive, negative, positive, negative, and positive. A lens having a five-group structure consisting of lens units having a refractive power of 2 is known. The configuration of the second lens unit having a negative refractive power includes a negative meniscus lens having a strong concave surface on the image surface side, a negative lens having a concave shape on both lens surfaces, a positive lens, and a negative lens having a concave surface on the object side. There are many four-lens configurations. The positive lens in the second lens group uses a high refractive index material for correcting spherical aberration, coma aberration, and the like, and a highly dispersed material for correcting chromatic aberration. For this reason, when a glass material satisfying this condition is selected from glass materials that are currently in practical use, since only those having a large partial dispersion ratio θgF exist, the secondary spectrum of lateral chromatic aberration on the wide-angle side tends to increase.

  Therefore, in each embodiment, the second lens unit L2 is configured to include three negative lenses and two positive lenses. Among the positive lenses, the glass material of the positive lens P2A having a large refractive power is selected in a range that satisfies the conditional expressions (1) and (2).

  Satisfying the conditional expression (1) uses a glass material on the relatively low dispersion side compared to the prior art. For this reason, the chromatic aberration generated in the second lens unit L2 becomes large with only one positive lens. Therefore, by using at least one more positive lens P2B, achromaticity is performed and chromatic aberration generated in the second lens unit L2 is reduced.

  The second lens unit L2 includes, in order from the object side to the image side, a negative lens, negative lens, positive lens, negative lens, and positive lens having a concave surface on the image side and a meniscus shape.

  While satisfying the previous conditional expressions (1) and (2), the lens configuration of the second lens unit L2 is configured in this manner, thereby facilitating achromatization in the second lens unit L2.

The rear group LR has at least one lens unit having a positive refractive power that moves toward the object side during zooming from the wide-angle end to the telephoto end, and sets the partial dispersion ratio of the material of at least one positive lens in the lens group. When θgFa and the Abbe number are νda,
60 <νda (3)
−0.0015 × νda + 0.6425 <θgFa (4)
Is satisfied.

  An anomalous dispersion glass that satisfies the conditional expressions (3) and (4) is used in the lens unit having the positive refractive power of the rear lens group LR to reduce the secondary spectrum of magnification aberration that occurs mainly on the wide angle side. .

  The lens group having positive refractive power in the rear group LR described above is the fifth lens group L5, and the two positive lenses in the fifth lens group L5 are both conditional expressions (3) and (4). Is satisfied.

  The second lens unit L2 has at least one aspheric surface.

  At this time, the object-side surface of the most object-side meniscus negative lens in the second lens unit L2 has an aspherical shape in which positive refractive power increases from the lens center to the lens periphery. As a result, fluctuations in distortion due to zooming are kept small.

  When the focal lengths of the first lens group and the second lens group are f1 and f2, respectively, and the focal lengths of the entire system at the wide-angle end and the telephoto end are fw and ft, respectively.

Is satisfied.

  Conditional expression (5) defines the range of the focal length of the first lens unit L1 with respect to the focal length of the entire system at the wide-angle end. If the lower limit of conditional expression (5) is exceeded and the positive refractive power of the first lens unit L1 becomes too strong, it becomes difficult to ensure a back focus of a predetermined length. If the upper limit of conditional expression (5) is exceeded and the positive refractive power of the first lens unit L1 becomes too weak, the back focus becomes longer, but this is not good because the lens system becomes larger.

  Conditional expression (6) defines the range of the focal length of the second lens unit L2 with respect to the square root of the product of the focal length of the entire system at the wide angle end and the focal length of the entire system at the telephoto end. If the negative refractive power of the second lens unit L2 exceeds the lower limit of the conditional expression (6) and becomes too strong, it is advantageous for downsizing the lens system, but various aberrations that occur in the second lens unit L2 Becomes larger, and it becomes difficult to correct this in a balanced manner with other lens groups. If the upper limit of conditional expression (6) is exceeded and the negative refractive power of the second lens unit L2 becomes too weak, it is advantageous for aberration correction, but it is not good because the lens system becomes large.

  More preferably, the numerical ranges of conditional expressions (5) and (6) are set as follows.

  The order when i is counted from the object side to the image side is shown, and the focal length of the i-th lens group is fi.

At this time,
1.5 <f3 / | f2 | <2.5 (7)
2 <| f4 / f2 | <3.5 (8)
2 <f5 / | f2 | <5 (9)
Is satisfied.

  Conditional expression (7) defines the range of the focal length of the third lens unit L3 with respect to the absolute value of the focal length of the second lens unit L2. If the positive refractive power of the third lens unit L3 exceeds the lower limit value of the conditional expression (7) and becomes too strong, it is advantageous for downsizing the lens system, but various aberrations occurring in the third lens unit L3. Becomes larger, and it becomes difficult to correct this in a balanced manner with other lens groups. If the upper limit of conditional expression (7) is exceeded and the positive refractive power of the third lens unit L3 becomes too weak, it is advantageous for aberration correction, but it is not good because the lens system becomes large.

  Conditional expression (8) defines the range of the absolute value of the focal length of the fourth lens unit L4 with respect to the absolute value of the focal length of the second lens unit L2. When the lower limit of conditional expression (8) is exceeded and the negative refractive power of the fourth lens unit L4 becomes too strong, various aberrations that occur in the fourth lens unit L4 increase, and this is corrected in a balanced manner by other lens units. Difficult to do. If the negative refractive power of the fourth lens unit L4 becomes too weak beyond the upper limit of conditional expression (8), it is advantageous for aberration correction, but the amount of movement of each lens unit for obtaining a predetermined zoom ratio is large. It is not good because it becomes larger and the lens system becomes larger.

  Conditional expression (9) defines the range of the focal length of the fifth lens unit L5 relative to the absolute value of the focal length of the second lens unit L2. If the positive refractive power of the fifth lens unit L5 is too strong beyond the lower limit of conditional expression (9), it is advantageous for securing a long back focus, but various aberrations generated in the fifth lens unit L5 are large. Therefore, it becomes difficult to correct this with other lens groups in a balanced manner. If the upper limit of conditional expression (9) is exceeded and the positive refractive power of the fifth lens unit L5 becomes too weak, it is advantageous for aberration correction, but it is not good because the lens system becomes large.

  More preferably, the numerical ranges of the conditional expressions (7) to (9) are set as follows.

1.6 <f3 / | f2 | <2.0 (7a)
2.2 <| f4 / f2 | <3.0 (8a)
2.3 <f5 / | f2 | <4.0 (9a)
When the back focus at the wide angle end is SKw, and the focal length of the entire system at the wide angle end is fw,
1.8 <SKw / fw <2.9 (10)
Is satisfied.

  Conditional expression (10) defines the ratio of the back focus at the wide angle end to the focal length at the wide angle end. This means that a space for arranging members such as a quick return mirror, a low-pass filter, and an infrared cut filter is secured on the image plane side of the zoom lens. Exceeding the lower limit value of conditional expression (10) and the back focus at the wide-angle end being shortened are not good because the space for arranging the aforementioned members becomes too small. Further, if the back focus at the wide-angle end becomes too long beyond the upper limit value of conditional expression (10), the total lens length becomes long, which is not good.

  The back focus here is the length from the last lens surface (surface having refractive power) to the image plane in air, and is the length when a low-pass filter, an infrared cut filter, etc. are excluded. .

  More preferably, the numerical range of conditional expression (10) is set as follows.

1.9 <SKw / fw <2.5 (10a)
The order when i is counted from the object side to the image side is shown, and when the air space between the i-th lens group and the i + 1-th lens group at the wide-angle end and the telephoto end is Diw, Dit,
D1w <D1t
D2w> D2t
D3w <D3t
D4w> D4t
Is satisfied.

  In this way, by allocating the zooming to each lens group during zooming, it is possible to achieve a predetermined zoom ratio with a small amount of movement, and the entire lens system is made compact.

  The lens surface closest to the object side in the fifth lens unit L5 has an aspherical shape in which the positive refractive power decreases as it goes from the lens center to the lens periphery, and mainly corrects curvature of field. The third lens unit L3 uses an aspheric surface having a shape in which the positive refractive power decreases from the lens center to the lens periphery, thereby reducing variations in spherical aberration mainly due to zooming.

  Focusing from an infinite object to a close object is performed by moving the second lens unit L2 toward the object side in the optical axis direction. By using the so-called inner focus method in this way, the lens diameter of the first lens unit L1 can be reduced compared to the case where focusing is performed by the first lens unit L1, and further, the overall length of the lens can be easily reduced. .

  The fourth lens unit L4 is divided into a fourth lens unit L4a having a negative refractive power and a fourth lens unit L4b having a negative refractive power, and the fourth a lens unit L4a is moved so as to have a component substantially perpendicular to the optical axis. Thus, so-called vibration isolation is performed to prevent image blurring deterioration due to camera shake or the like.

  As described above, the zoom lens of each embodiment has a positive refractive power as a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power in order from the object side to the image side. It has the rear group LR that it has. By configuring the second lens unit L2 as described above, the entire system is compact, and high optical performance is obtained in which chromatic aberration is well corrected from the wide-angle end to the telephoto end.

  In particular, a zoom lens capable of excellent correction of chromatic aberration, in particular, the secondary spectrum of lateral chromatic aberration, without increasing the number of used glass or fluorite including anomalous dispersion characteristics including a wide-angle region has been obtained. .

  Numerical examples 1 to 4 of the present invention are shown below. In each numerical example, i indicates the order of the surfaces from the object side, ri is the radius of curvature of the i-th surface from the object side, di is the i-th and i + 1-th interval from the object side, ni and νi Are the refractive index and Abbe number for the d-line of the i-th optical member. f, fno, and 2ω represent the focal length, F number, and angle of view of the entire system when focusing on an object at infinity, respectively.

  Similarly, the refractive index of the material of the i-th lens Gi from the object side to the image side with respect to d, g, c, and f lines is also shown.

The aspherical 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 eccentricity, and b, c, d, and e are aspherical surfaces. As a coefficient
X = (1 / R) H ² / (1+ (1− (1 + k) (H / R) ² ) ^1/2 )
+ BH ⁴ + CH ⁶ + dH ⁸ + eH ¹⁰
It is expressed by the following formula.

For example, the display of “E-Z” means “10 ^−Z ”.

Table 1 shows the relationship between the above-described conditional expressions and numerical values in the numerical examples.

Numerical example 1
f = 17.5-53.4 fno = 1: 2.9 2ω = 75.9 ° -28.7 °
r 1 = 217.373 d 1 = 1.90 n 1 = 1.84666 ν 1 = 23.9
r 2 = 74.677 d 2 = 8.65 n 2 = 1.60311 ν2 = 60.6
r 3 = -799.538 d 3 = 0.15
r 4 = 48.982 d 4 = 7.03 n 3 = 1.71300 ν3 = 53.9
r 5 = 122.553 d 5 = variable
r 6 = 74.290 (aspherical surface) d 6 = 0.05 n 4 = 1.51640 ν4 = 52.2
r 7 = 59.996 d 7 = 1.20 n 5 = 1.80400 ν5 = 46.6
r 8 = 12.277 d 8 = 6.81
r 9 = -37.400 d 9 = 1.00 n 6 = 1.83481 ν6 = 42.7
r10 = 37.400 d10 = 0.15
r11 = 27.209 d11 = 4.93 n 7 = 1.83400 ν7 = 37.2
r12 = -36.493 d12 = 0.53
r13 = -25.912 d13 = 0.90 n 8 = 1.80400 ν8 = 46.6
r14 = 25.912 d14 = 3.60 n 9 = 1.80518 ν9 = 25.4
r15 = -225.909 d15 = variable
r16 = Flare cut aperture d16 = 0.00
r17 = 254.806 d17 = 3.50 n10 = 1.58913 ν10 = 61.1
r18 = -39.891 d18 = 1.00
r19 = Aperture stop d 19 = 2.32
r20 = 36.378 (aspherical surface) d20 = 8.54 n11 = 1.58313 ν11 = 59.4
r21 = -16.418 d21 = 2.50 n12 = 1.84666 ν12 = 23.9
r22 = -26.192 d22 = variable
r23 = -51.807 d23 = 2.61 n13 = 1.84666 ν13 = 23.9
r24 = -18.890 d24 = 0.80 n14 = 1.69680 ν14 = 55.5
r25 = 61.977 d25 = 5.05
r26 = -28.304 d26 = 1.20 n15 = 1.84666 ν15 = 23.9
r27 = -85.924 d27 = 1.98 n16 = 1.58913 ν16 = 61.1
r28 = -39.814 d28 = variable
r29 = 129.162 (aspherical surface) d29 = 0.08 n17 = 1.51640 ν17 = 52.2
r30 = 154.426 d30 = 1.32 n18 = 1.83400 ν18 = 37.2
r31 = 36.157 d31 = 6.47 n19 = 1.49700 ν19 = 81.5
r32 = -36.157 d32 = 0.15
r33 = 64.804 d33 = 8.20 n20 = 1.49700 ν20 = 81.5
r34 = -23.782 d34 = 1.70 n21 = 1.74950 ν21 = 35.3
r35 = -38.936

Focal length 17.50 28.70 53.44
Variable interval
d 5 3.30 16.65 32.55
d 15 17.20 9.08 2.26
d 22 2.20 6.49 10.69
d 28 9.72 5.44 1.23
kinF 35.29 39.38 47.67

Aspherical coefficient 6th surface B c de
1.457415e-05 -3.790177e-08 6.739559e-11 -1.117466e-13
20th surface B c de
-8.402971e-06 -1.432432e-08 9.773360e-11 -2.555962e-13
No. 29 B c de
-6.201996e-06 1.518167e-08 -5.562855e-11 1.910063e-13



Numerical example 2
f = 17.6-53.5 fno = 1: 2.9 2ω = 75.8 ° -28.7 °
r 1 = 223.608 d 1 = 2.00 n 1 = 1.84666 ν1 = 23.9
r 2 = 74.292 d 2 = 8.00 n 2 = 1.71300 ν2 = 53.9
r 3 = 753.184 d 3 = 0.15
r 4 = 56.699 d 4 = 6.85 n 3 = 1.71300 ν3 = 53.9
r 5 = 156.652 d 5 = variable
r 6 = 151.553 (aspherical surface) d 6 = 0.08 n 4 = 1.52421 ν4 = 51.4
r 7 = 75.460 d 7 = 1.20 n 5 = 1.80400 ν5 = 46.6
r 8 = 14.406 d 8 = 6.90
r 9 = -38.154 d 9 = 1.00 n 6 = 1.83481 ν6 = 42.7
r10 = 34.113 d10 = 0.15
r11 = 29.904 d11 = 6.18 n 7 = 1.85026 ν7 = 32.3
r12 = -34.673 d12 = 1.04
r13 = -20.470 d13 = 1.10 n 8 = 1.83481 ν8 = 42.7
r14 = 113.547 d14 = 2.76 n 9 = 1.76182 ν9 = 26.5
r15 = -44.975 d15 = variable
r16 = Flare cut aperture d16 = 0.00
r17 = 91.970 d17 = 4.00 n10 = 1.70154 ν10 = 41.2
r18 = -55.085 d18 = 1.00
r19 = Aperture stop d19 = 1.68
r20 = 49.212 d20 = 4.59 n11 = 1.62299 ν11 = 58.2
r21 = -30.911 d21 = 1.20 n12 = 1.84666 ν12 = 23.9
r22 = -243.465 d22 = 0.15
r23 = 139.830 d23 = 3.55 n13 = 1.58313 ν13 = 59.4
r24 = -45.129 (aspherical surface) d24 = variable
r25 = -55.323 d25 = 2.65 n14 = 1.84666 ν14 = 23.9
r26 = -19.675 d26 = 0.80 n15 = 1.71300 ν15 = 53.9
r27 = 55.427 d27 = 5.06
r28 = -18.369 d28 = 1.30 n16 = 1.84666 ν16 = 23.9
r29 = -31.472 d29 = 2.77 n17 = 1.56384 ν17 = 60.7
r30 = -20.827 d30 = variable
r31 = 178.749 (aspherical surface) d31 = 1.40 n18 = 1.83400 ν18 = 37.2
r32 = 51.188 d32 = 6.17 n19 = 1.49700 ν19 = 81.5
r33 = -33.030 d33 = 0.15
r34 = 64.597 d34 = 7.79 n20 = 1.43875 ν20 = 95.0
r35 = -23.981 d35 = 1.70 n21 = 1.74950 ν21 = 35.3
r36 = -40.355

Focal length 17.56 32.24 53.48
Variable interval
d 5 3.66 22.77 35.80
d 15 18.69 7.91 1.43
d 24 1.91 7.04 11.52
d 30 10.39 5.26 0.78
kinF 35.08 40.14 46.98

Aspherical coefficient 6th surface B c de
2.366100e-05 -7.419836e-08 2.614834e-10 -2.601540e-13
No. 24 B c de
5.394064e-06 1.270430e-08 -1.149192e-10 4.704737e-13
31st surface B c de
-2.882469e-06 7.626800e-09 -2.682456e-11 5.805594e-14



Numerical Example 3
f = 17.6-53.5 fno = 1: 2.9 2ω = 75.8 ° -28.7 °
r 1 = 224.523 d 1 = 2.00 n 1 = 1.84666 ν1 = 23.9
r 2 = 69.716 d 2 = 8.24 n 2 = 1.71300 ν2 = 53.9
r 3 = 727.700 d 3 = 0.15
r 4 = 54.571 d 4 = 7.04 n 3 = 1.71300 ν3 = 53.9
r 5 = 160.021 d 5 = variable
r 6 = 175.325 (aspherical surface) d 6 = 0.08 n 4 = 1.52421 ν4 = 51.4
r 7 = 74.902 d 7 = 1.20 n 5 = 1.77250 ν5 = 49.6
r 8 = 13.343 d 8 = 6.74
r 9 = -43.218 d 9 = 1.00 n 6 = 1.83481 ν6 = 42.7
r10 = 50.929 d10 = 0.15
r11 = 33.704 d11 = 4.47 n 7 = 1.83400 ν7 = 37.2
r12 = -58.516 d12 = 1.60
r13 = -19.122 d13 = 1.10 n 8 = 1.80400 ν8 = 46.6
r14 = 149.586 d14 = 2.69 n 9 = 1.84666 ν9 = 23.9
r15 = -40.439 d15 = variable
r16 = Flare cut aperture d16 = 0.00
r17 = 61.659 d17 = 4.00 n10 = 1.51633 ν10 = 64.1
r18 = -42.423 d18 = 1.00
r19 = Aperture stop d19 = 1.68
r20 = 48.836 (aspherical surface) d20 = 7.18 n11 = 1.58313 ν11 = 59.4
r21 = -18.938 d21 = 1.40 n12 = 1.84666 ν12 = 23.9
r22 = -28.812 d22 = variable
r23 = -46.118 d23 = 3.13 n13 = 1.84666 ν13 = 23.9
r24 = -17.935 d24 = 0.80 n14 = 1.71300 ν14 = 53.9
r25 = 68.666 d25 = 5.36
r26 = -26.651 d26 = 1.30 n15 = 1.84666 ν15 = 23.9
r27 = -90.221 d27 = 3.22 n16 = 1.48749 ν16 = 70.2
r28 = -27.740 d28 = variable
r29 = 67.879 (aspherical surface) d29 = 1.40 n17 = 1.83400 ν17 = 37.2
r30 = 33.134 d30 = 7.49 n18 = 1.49700 ν18 = 81.5
r31 = -34.462 d31 = 0.15
r32 = 93.341 d32 = 7.11 n19 = 1.49700 ν19 = 81.5
r33 = -25.633 d33 = 1.70 n20 = 1.74950 ν20 = 35.3
r34 = -49.869

Focal length 17.56 33.13 53.49
Variable interval
d 5 3.54 22.30 34.49
d 15 17.23 7.05 1.45
d 22 1.95 7.50 11.11
d 28 9.95 4.40 0.79
kinF 35.09 40.05 47.00

Aspherical coefficient 6th surface B c de
2.787928e-05 -8.535193e-08 2.858855e-10 -2.859387e-13
20th surface B c de
-1.196077e-05 -1.273960e-08 1.028722e-10 -3.649232e-13
No. 29 B c de
-2.809630e-06 1.303811e-08 -7.214413e-11 2.150567e-13


Numerical Example 4
f = 17.6-53.5 fno = 1: 2.9 2ω = 75.8 ° -28.7 °
r 1 = 223.998 d 1 = 2.00 n 1 = 1.84666 ν1 = 23.9
r 2 = 68.670 d 2 = 8.43 n 2 = 1.71300 ν2 = 53.9
r 3 = 842.660 d 3 = 0.15
r 4 = 54.455 d 4 = 7.10 n 3 = 1.71300 ν3 = 53.9
r 5 = 165.442 d 5 = variable
r 6 = 193.952 (aspherical surface) d 6 = 0.08 n 4 = 1.52421 ν4 = 51.4
r 7 = 79.212 d 7 = 1.20 n 5 = 1.77250 ν5 = 49.6
r 8 = 13.179 d 8 = 6.60
r 9 = -43.430 d 9 = 1.00 n 6 = 1.83481 ν6 = 42.7
r10 = 53.044 d10 = 0.15
r11 = 34.427 d11 = 4.40 n 7 = 1.83400 ν7 = 37.2
r12 = -57.174 d12 = 1.48
r13 = -19.452 d13 = 1.10 n 8 = 1.80400 ν8 = 46.6
r14 = 94.049 d14 = 2.73 n 9 = 1.84666 ν9 = 23.9
r15 = -43.384 d15 = variable
r16 = Flare cut aperture d16 = 0.00
r17 = 63.048 d17 = 4.00 n10 = 1.51633 ν10 = 64.1
r18 = -43.046 d18 = 1.00
r19 = Aperture stop d19 = 1.68
r20 = 46.885 (aspherical surface) d20 = 8.46 n11 = 1.58313 ν11 = 59.4
r21 = -18.432 d21 = 1.50 n12 = 1.84666 ν12 = 23.9
r22 = -27.966 d22 = variable
r23 = -47.631 d23 = 3.16 n13 = 1.84666 ν13 = 23.9
r24 = -18.114 d24 = 0.80 n14 = 1.71300 ν14 = 53.9
r25 = 62.441 d25 = 5.25
r26 = -27.320 d26 = 1.30 n15 = 1.84666 ν15 = 23.9
r27 = -104.690 d27 = 3.16 n16 = 1.48749 ν16 = 70.2
r28 = -29.617 d28 = variable
r29 = 66.348 (aspherical surface) d29 = 1.40 n17 = 1.83400 ν17 = 37.2
r30 = 34.187 d30 = 0.07
r31 = 33.653 d31 = 7.27 n18 = 1.49700 ν18 = 81.5
r32 = -35.005 d32 = 0.15
r33 = 98.702 d33 = 7.28 n19 = 1.49700 ν19 = 81.5
r34 = -25.109 d34 = 0.08
r35 = -25.085 d35 = 1.70 n20 = 1.74950 ν20 = 35.3
r36 = -46.868

Focal length 17.56 33.03 53.48
Variable interval
d 5 3.48 21.91 33.79
d 15 16.87 7.03 1.43
d 22 1.95 7.07 10.26
d 28 9.14 4.01 0.82
kinF 35.08 40.40 48.04

Aspherical coefficient 6th surface B c de
2.875922e-05 -8.692215e-08 2.658157e-10 -2.499509e-13
20th surface B c de
-1.210348e-05 -1.180873e-08 9.305176e-11 -3.053666e-13
No. 29 B c de
-3.670667e-06 1.219098e-08 -6.645631e-11 1.718782e-13




Numerical example 1
Refractive index
d g c F
G1 1.846660 1.893856 1.836554 1.871929
G2 1.603112 1.615409 1.600078 1.610024
G3 1.712995 1.729435 1.708974 1.722210
Resin 1.516400 1.528843 1.513427 1.523331
G4 1.804000 1.825699 1.798815 1.816080
G5 1.834807 1.859527 1.828974 1.848514
G6 1.834000 1.862781 1.827376 1.849819
G7 1.804000 1.825699 1.798815 1.816080
G8 1.805181 1.847285 1.796106 1.827775
G9 1.589130 1.601034 1.586188 1.595824
G10 1.583126 1.595279 1.580134 1.589954
G11 1.846660 1.893856 1.836554 1.871929
G12 1.846660 1.893856 1.836554 1.871929
G13 1.696797 1.712339 1.692974 1.705522
G14 1.846660 1.893856 1.836554 1.871929
G15 1.589130 1.601034 1.586188 1.595824
Resin 1.516400 1.528843 1.513427 1.523331
G16 1.834000 1.862781 1.827376 1.849819
G17 1.496999 1.504509 1.495138 1.501233
G18 1.496999 1.504509 1.495138 1.501233
G19 1.749500 1.776810 1.743260 1.764470

Numerical example 2
Refractive index
d g c F
G1 1.846660 1.893856 1.836554 1.871929
G2 1.712995 1.729435 1.708974 1.722210
G3 1.712995 1.729435 1.708974 1.722210
Resin 1.524210 1.537048 1.521150 1.531355
G4 1.804000 1.825699 1.798815 1.816080
G5 1.834807 1.859527 1.828974 1.848514
G6 1.850259 1.884505 1.842582 1.868918
G7 1.834807 1.859527 1.828974 1.848514
G8 1.761821 1.799923 1.753567 1.782296
G9 1.701536 1.723323 1.696503 1.713515
G10 1.622992 1.636296 1.619739 1.630450
G11 1.846660 1.893856 1.836554 1.871929
G12 1.583126 1.595279 1.580134 1.589954
G13 1.846660 1.893856 1.836554 1.871929
G14 1.712995 1.729435 1.708974 1.722210
G15 1.846660 1.893856 1.836554 1.871929
G16 1.563839 1.575316 1.561001 1.570295
G17 1.834000 1.862781 1.827376 1.849819
G18 1.496999 1.504509 1.495138 1.501233
G19 1.438750 1.444420 1.437334 1.441953
G20 1.749500 1.776810 1.743260 1.764470

Numerical Example 3
Refractive index
d g c F
G1 1.846660 1.893856 1.836554 1.871929
G2 1.712995 1.729435 1.708974 1.722210
G3 1.712995 1.729435 1.708974 1.722210
Resin 1.524210 1.537048 1.521150 1.531355
G4 1.772499 1.791972 1.767798 1.783374
G5 1.834807 1.859527 1.828974 1.848514
G6 1.834000 1.862781 1.827376 1.849819
G7 1.804000 1.825699 1.798815 1.816080
G8 1.846660 1.893856 1.836554 1.871929
G9 1.516330 1.526214 1.513855 1.521905
G10 1.583126 1.595279 1.580134 1.589954
G11 1.846660 1.893856 1.836554 1.871929
G12 1.846660 1.893856 1.836554 1.871929
G13 1.712995 1.729435 1.708974 1.722210
G14 1.846660 1.893856 1.836554 1.871929
G15 1.487490 1.495964 1.485344 1.492285
G16 1.834000 1.862781 1.827376 1.849819
G17 1.496999 1.504509 1.495138 1.501233
G18 1.496999 1.504509 1.495138 1.501233
G19 1.749500 1.776810 1.743260 1.764470


Numerical Example 4
Refractive index
d g c F
G1 1.846660 1.893856 1.836554 1.871929
G2 1.712995 1.729435 1.708974 1.722210
G3 1.712995 1.729435 1.708974 1.722210
Resin 1.524210 1.537048 1.521150 1.531355
G4 1.772499 1.791972 1.767798 1.783374
G5 1.834807 1.859527 1.828974 1.848514
G6 1.834000 1.862781 1.827376 1.849819
G7 1.804000 1.825699 1.798815 1.816080
G8 1.846660 1.893856 1.836554 1.871929
G9 1.516330 1.526214 1.513855 1.521905
G10 1.583126 1.595279 1.580134 1.589954
G11 1.846660 1.893856 1.836554 1.871929
G12 1.846660 1.893856 1.836554 1.871929
G13 1.712995 1.729435 1.708974 1.722210
G14 1.846660 1.893856 1.836554 1.871929
G15 1.487490 1.495964 1.485344 1.492285
G16 1.834000 1.862781 1.827376 1.849819
G17 1.496999 1.504509 1.495138 1.501233
G18 1.496999 1.504509 1.495138 1.501233
G19 1.749500 1.776810 1.743260 1.764470

  Next, the zoom lens shown in Examples 1 to 4 will be described using Example 13 in which the zoom lens is applied to an imaging apparatus.

  FIG. 13 is a schematic view of the main part of a single-lens reflex camera. In FIG. 13, reference numeral 10 denotes a photographing lens having the zoom lens 1 according to the first to fourth embodiments. The zoom lens 1 is held by a lens barrel 2 that is a holding member. Reference numeral 20 denotes a camera body, which includes a quick return mirror 3 that reflects the light beam from the photographing lens 10 upward, a focusing plate 4 that is disposed at an image forming position of the photographing lens 10, and an inverted image formed on the focusing plate 4. It is composed of a penta roof prism 5 for converting to an eyepiece, an eyepiece 6 for observing the erect image, and the like. Reference numeral 7 denotes a photosensitive surface, on which a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor, or a silver salt film is disposed. At the time of photographing, the quick return mirror 3 is retracted from the optical path, and an image is formed on the photosensitive surface 7 by the photographing lens 10.

  The benefits described in the first to fourth embodiments are effectively enjoyed in the imaging apparatus as disclosed in the present embodiment.

Lens cross-sectional view of the zoom lens of Example 1 Various aberration diagrams at the wide-angle end of the zoom lens of Example 1 Various aberration diagrams at the telephoto end of the zoom lens of Example 1 Lens sectional view of the zoom lens of Example 2 Various aberration diagrams at the wide-angle end of the zoom lens of Example 2 Various aberration diagrams at the telephoto end of the zoom lens of Example 2 Lens sectional view of the zoom lens of Example 3 Various aberration diagrams at the wide-angle end of the zoom lens of Example 3 Various aberration diagrams at the telephoto end of the zoom lens of Example 3 Lens sectional view of the zoom lens of Example 4 Various aberration diagrams at the wide-angle end of the zoom lens of Example 4 Various aberration diagrams at the telephoto end of the zoom lens of Example 4 Schematic diagram of main parts of an imaging apparatus of the present invention

Explanation of symbols

L1 1st lens group L2 2nd lens group L3 3rd lens group L4 4th lens group L5 5th lens group SSP Flare cut stop SP Aperture IP Image surface d d line g g line C C line FF line S / C sine Condition ΔdM d-line meridional image plane ΔdS d-line sagittal image plane

Claims (11)

In order from the object side to the image side, the lens unit includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a rear group having a positive refractive power as a whole. In a zoom lens that performs zooming by changing the distance between the lens groups and the distance between the second lens group and the rear group, the second lens group includes three negative lenses and two positive lenses. When the Abbe number and partial dispersion ratio of the positive lens material having the most positive refractive power in the lens group are νd and θgF,
30 <νd
θgF <−1.79 × 10 ⁻³ · νd +0.654
A zoom lens characterized by satisfying the following conditions:   2. The zoom according to claim 1, wherein the second lens group includes, in order from the object side to the image side, a negative lens, negative lens, positive lens, negative lens, and positive lens having a concave surface on the image side and a meniscus shape. lens. The rear group has at least one lens unit having a positive refractive power that moves toward the object side during zooming from the wide-angle end to the telephoto end, and a partial dispersion ratio of the material of at least one positive lens in the lens group Is θgFa and the Abbe number is νda,
−0.0015 × νda + 0.6425 <θgFa
60 <νda
The zoom lens according to claim 1 or 2, wherein the following condition is satisfied.   The zoom lens according to claim 1, wherein the second lens group has at least one aspheric surface. When the focal lengths of the first lens group and the second lens group are f1 and f2, respectively, and the focal lengths of the entire system at the wide-angle end and the telephoto end are fw and ft, respectively.
The zoom lens according to claim 1, wherein the following condition is satisfied. In order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a positive lens group In a zoom lens having a fifth lens unit having a refractive power and moving each lens unit so that the air spacing between the lens units changes during zooming from the wide-angle end to the telephoto end, i is an image from the object side. When the distance between the i-th lens group and the i + 1-th lens group at the wide-angle end and the telephoto end is Diw, Dit, and the focal length of the i-th lens group is fi,
D1w <D1t
D2w> D2t
D3w <D3t
D4w> D4t
1.5 <f3 / | f2 | <2.5
2 <| f4 / f2 | <3.5
2 <f5 / | f2 | <5
A zoom lens characterized by satisfying the following conditions:   The zoom lens according to claim 1, wherein focusing is performed by moving the second lens group in an optical axis direction.   8. The imaging position is changed by moving all or a part of the fourth lens group so as to have a component perpendicular to the optical axis. Zoom lens. When the back focus at the wide angle end is SKw and the focal length of the entire system at the wide angle end is fw,
1.8 <SKw / fw <2.9
The zoom lens according to claim 1, wherein the following condition is satisfied.   The zoom lens according to claim 1, wherein an image is formed on a solid-state image sensor.   An image pickup apparatus comprising: the zoom lens according to claim 1; and a solid-state image pickup device that receives an image formed by the zoom lens.