Zoom lens system

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a zoom lens system which is suitable for use in a broadcasting television camera, a video camera, a digital still camera, and a silver-halide camera, and also to an image pickup apparatus including the zoom lens system.

2. Description of the Related Art

Conventionally, as a zoom lens system used for an image pickup apparatus such as a television camera, a silver halide film camera, a digital camera, and a video camera, there is proposed a zoom lens system including, in order from the object side, a first lens unit having positive refractive power and including a focus unit, a second lens unit having negative refractive power for magnification-varying, a third lens unit having positive or negative refractive power for correcting image plane variation due to the magnification-varying, and a fourth lens unit having positive refractive power for image formation.

Japanese Patent Application Laid-Open No. 2004-264458 discloses a zoom lens system in which the third lens unit has a positive refractive power. Japanese Patent Application Laid-Open No. H09-005628 discloses a zoom lens system in which the third lens unit has a negative refractive power.

Japanese Patent Application Laid-Open No. 2004-264458 discloses a technology for appropriately correcting longitudinal chromatic aberration in particular by defining a refractive index, an Abbe constant, a shape, or the like of the first lens.

Japanese Patent Application Laid-Open No. H09-005628 discloses a technology for realizing a zoom lens system with small spherical aberration and chromatic aberration in particular by defining a structure of positive and negative lenses in the first lens unit and an Abbe constant thereof.

However, there is a problem that if it is intended to correct longitudinal chromatic aberration due to an increase in a focal length at a telephoto end because of a higher magnification ratio or to correct further longitudinal chromatic aberration on the telephoto side in the already disclosed zoom lens system, it is difficult to correct the longitudinal chromatic aberration sufficiently by the conventional technology.

SUMMARY OF THE INVENTION

In view of the above, an object of the present invention is to provide a zoom lens system that is optimal for a high magnification zoom lens system for broadcasting in particular, and can appropriately correct secondary spectrum of longitudinal chromatic aberration on a telephoto side while achieving a small size and light weight, and to provide an image pickup apparatus including the zoom lens system.

In order to attain the above-mentioned object, according to the present invention, there is provided a zoom lens system, including, in order from an object side; a first lens unit having a positive refractive power, a second lens unit having a negative refractive power that moves for magnification-varying, a third lens unit having one of a positive refractive power and a negative refractive power that moves for magnification-varying, and a fourth lens unit having a positive refractive power, in which when an Abbe constant of a positive lens Lp having a smallest Abbe constant among lenses constituting the first lens unit is denoted by νp, a partial dispersion ratio thereof is denoted by θp, a refractive power thereof is denoted by φp, an average value of Abbe constants of positive lenses except the positive lens Lp is denoted by νap, an average value of partial dispersion ratios of negative lenses of the first lens unit is denoted by θan, a refractive power of the first lens unit is denoted by φ1, and a refractive power of an entire zoom lens system at a telephoto end is denoted by φtele, the following conditional expressions are satisfied:

−0.03<(θp−θan)/θan<0.15;
0.005<(1/νp−1/νap)/(φ1/φtele)<0.030; and
0.05<φp/φ1<0.4.

Further, preferably, when an average value of Abbe constants of the negative lenses among the lenses constituting the first lens unit is denoted by νan, and a sum of refractive powers of the negative lenses is denoted by φn, the following conditional expressions may be satisfied.

0.05<(1/νan−1/νap)/(φp/φ1)<0.5
−1.0<φn/φ1<−0.4

More preferably, the following conditional expressions may be satisfied.

−0.5<φp/φ1<−0.1
|νp−νan|<15

Further, when a refractive power of the second lens unit is denoted by φ2, the following conditional expression is satisfied.

−0.1<φp/φ2<−0.01

Here, when a refractive index for g-line is denoted by Ng, a refractive index for F-line is denoted by NF, a refractive index for d-line is denoted by Nd, and a refractive index for C-line is denoted by NC, an Abbe constant ν and a partial dispersion ratio θ satisfy the following expressions, respectively.

Abbe constant ν=(Nd−1)/(NF−NC)
Partial dispersion ratio θ=(Ng−NF)/(NF−NC)

Further objects or other features of the present invention become apparent from the following description of exemplary embodiments and the like described with reference to the attached drawings.

According to the present invention, it is possible to provide the zoom lens system having a high magnification of zoom ratio that can appropriately correct secondary spectrum of longitudinal chromatic aberration at the telephoto end while achieving a small size and light weight.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating dichroic achromatism and remaining secondary spectrum of a positive lens unit.

FIG. 2 is a schematic diagram of distribution of an Abbe constant ν and a partial dispersion ratio θ of optical materials.

FIG. 3 is a cross sectional view at a wide angle end and in focus at infinity according to Numerical Embodiment 1.

FIG. 4A is an aberration diagram at the wide angle end and in focus at 3.0 m according to Numerical Embodiment 1.

FIG. 4B is an aberration diagram at a telephoto end and in focus at 3.0 m according to Numerical Embodiment 1.

FIG. 5 is a cross sectional view at the wide angle end and in focus at infinity according to Numerical Embodiment 2.

FIG. 6A is an aberration diagram at the wide angle end and in focus at 3.0 m according to Numerical Embodiment 2.

FIG. 6B is an aberration diagram at the telephoto end and in focus at 3.0 m according to Numerical Embodiment 2.

FIG. 7 is a cross sectional view at the wide angle end and in focus at infinity according to Numerical Embodiment 3.

FIG. 8A is an aberration diagram at the wide angle end and in focus at 3.0 m according to Numerical Embodiment 3.

FIG. 8B is an aberration diagram at the telephoto end and in focus at 3.0 m according to Numerical Embodiment 3.

FIG. 9 is a cross sectional view at the wide angle end and in focus at infinity according to Numerical Embodiment 4.

FIG. 10A is an aberration diagram at the wide angle end and in focus at 13 m according to Numerical Embodiment 4.

FIG. 10B is an aberration diagram at the telephoto end and in focus at 13 m according to Numerical Embodiment 4.

FIG. 11 is a cross sectional view at the wide angle end and in focus at infinity according to Numerical Embodiment 5.

FIG. 12A is an aberration diagram at the wide angle end and in focus at 13 m according to Numerical Embodiment 5.

FIG. 12B is an aberration diagram at the telephoto end and in focus at 13 m according to Numerical Embodiment 5.

DESCRIPTION OF THE EMBODIMENTS

An outline of a zoom lens system according to the present invention is described below.

The zoom lens system of the present invention includes at least, in order from an object side, a first lens unit having a positive refractive power that does not move for magnification-varying, a second lens unit having a negative refractive power that moves for magnification-varying, a third lens unit having a positive or negative refractive power for correcting image plane variation due to magnification-varying, and a fourth lens unit having a positive refractive power that does not move for magnification-varying but moves for image formation.

The first lens unit includes, in order from the object side, a first sub lens unit that does not move for focusing, and a second sub lens unit having a positive refractive power that moves for focusing.

Conditional expressions in the present invention are described.

It is defined that an Abbe constant of a positive lens Lp having a smallest Abbe constant among lenses of the first lens unit is denoted by νp, a partial dispersion ratio thereof is denoted by θp, a refractive power thereof is denoted by φp, an average value of Abbe constants of positive lenses except the positive lens Lp is denoted by νap, an average value of partial dispersion ratios of negative lenses of the first lens unit is denoted by θan, a refractive power of the first lens unit is denoted by φ1, and a refractive power of the entire zoom lens system at the telephoto end is denoted by φtele. Then, it suffices that the following conditional expressions (1) to (3) be satisfied.

−0.03<(θp−θan)/θan<0.15 (1)
0.005<(1/νp−1/νap)/(φ1/φtele)<0.030 (2)
0.05<φp/φ1<0.4 (3)

Preferably, when an average value of Abbe constants of negative lenses among the lenses constituting the first lens unit is denoted by νan, and a sum of refractive powers of the negative lenses is denoted by φn, the following conditional expressions (4) and (5) may be satisfied.

0.05<(1/νan−1/νap)/(φp/φ1)<0.5 (4)
−1.0<φn/φ1<−0.4 (5)

More preferably, the following conditional expressions (6) and (7) may be satisfied.

−0.5<φp/φ1<−0.1 (6)
|νp−νan|<15 (7)

In addition, when a refractive power of the second lens unit is denoted by φ2, it suffices that the following conditional expression (8) be satisfied.

−0.1<φp/φ2<−0.01 (8)

Here, when a refractive index for g-line is denoted by Ng, a refractive index for F-line is denoted by NF, a refractive index for d-line is denoted by Nd, and a refractive index for C-line is denoted by NC, an Abbe constant ν and a partial dispersion ratio θ satisfy the following expressions (9) and (10), respectively.

ν=(Nd−1)/(NF−NC) (9)
θ=(Ng−NF)/(NF−NC) (10)

In each conditional expression, a structure of the zoom lens system, dispersion characteristic of lens material, and condition of refractive power are defined, to thereby define a condition for correcting secondary spectrum of longitudinal chromatic aberration at the telephoto end and for realizing good optical performance.

The conditional expressions (1) to (8) define the conditions for reducing a remaining secondary spectrum amount of longitudinal chromatic aberration in the first lens unit and for appropriately correcting the secondary spectrum of the longitudinal chromatic aberration at the telephoto end. An outline of the conditions is described with reference to FIGS. 1 and 2.

FIG. 1 illustrates a schematic diagram illustrating dichroic achromatism and remaining secondary spectrum of the positive lens unit.

FIG. 2 illustrates a schematic diagram of distribution of an Abbe constant ν and a partial dispersion ratio θ of existing optical materials.

As illustrated in FIG. 2, the existing optical material is distributed in the region having narrow partial dispersion ratio θ with respect to the Abbe constant ν, and there is a tendency that the partial dispersion ratio θ increases as the Abbe constant ν decreases.

A correction condition of chromatic aberration of a thin lens system which has a predetermined refractive power φ and is constituted of two lenses 1 and 2 having refractive powers φ1 and φ2 and Abbe constants ν1 and ν2, respectively, is expressed by the following equation.

ν1/ν1+φ2/ν2=0 (11)

Here, φ is expressed as follows.

φ=φ1+φ2 (12)

If the equation (11) is satisfied, an image formation position is identical between the C-line and the F-line.

In this case, the refractive powers φ1 and φ2 are expressed by the following equations by solving the equations (11) and (12).

φ1=φ×ν1/(ν1−ν2) (13)
φ2=−φ×ν2/(ν1−ν2) (14)

In FIG. 1, as to the achromatism for the positive lens unit, a material having a large Abbe constant ν1 is used for the positive lens 1, and a material having a small Abbe constant ν2 is used for the negative lens 2. Therefore, the positive lens 1 has a small partial dispersion ratio θ1, and the negative lens 2 has a large partial dispersion ratio θ2 as illustrated in FIG. 2. Thus, if the chromatic aberration is corrected at the F-line and the C-line, the image formation point at the g-line is shifted to the image side. This deviation amount defined as a secondary spectrum amount Δ is expressed by the following equation.

Δ=−(1/φ)×(θ1−θ2)/(ν1−ν2) (15)

Here, it is defined that the secondary spectrum amounts of the first sub lens unit, the second sub lens unit, and the lens units after the magnification-varying system are denoted by Δ1a, Δ1b, and ΔZ, respectively. Image formation zooming factors of the second sub lens unit and the lens units after the magnification-varying system are denoted by β1b and βZ, respectively. Then, the secondary spectrum amount Δ of the entire lens system is expressed by the following equation.

Δ=Δ1a×β1b²×βZ²+Δ1b×(1−β1b)×βZ²+ΔZ×(1−βZ) (16)

The secondary spectrum amount Δ becomes significant in the first sub lens unit and the second sub lens unit in which an axial marginal light beam passes through at a high position on the telephoto side. Therefore, the secondary spectrum amount Δ of the longitudinal chromatic aberration may be reduced on the telephoto side by suppressing the sum of the secondary spectrum amounts Δ1a and Δ1b of the longitudinal chromatic aberration generated in the first sub lens unit and the second sub lens unit.

The conditional expression (1) defines a relationship of partial dispersion ratios θ of positive and negative lenses for appropriately correcting the secondary spectrum of the longitudinal chromatic aberration at the telephoto end.

If the upper limit condition of the conditional expression (1) is not satisfied, the secondary spectrum of the longitudinal chromatic aberration at the telephoto end is corrected excessively, and it becomes difficult to maintain performance balance between the longitudinal chromatic aberration and lateral chromatic aberration in the entire zoom range. In addition, if the lower limit condition of the conditional expression (1) is not satisfied, it becomes difficult to suppress the secondary spectrum of the longitudinal chromatic aberrations at the telephoto end.

The conditional expression (2) defines a relationship between the Abbe constant ν of the positive lenses and the refractive power φtele at the telephoto end, in order to satisfy both achromatism for the C-line and the F-line and the correction of the secondary spectrum at the telephoto end.

If the upper limit condition of the conditional expression (2) is not satisfied, the secondary spectrum of the longitudinal chromatic aberration at the telephoto end is corrected excessively, and it becomes difficult to maintain performance balance between the longitudinal chromatic aberration and the lateral chromatic aberration in the entire zoom range. In addition, because the refractive power φtele increases and the focal length decreases, it becomes difficult to achieve high magnification ratio. If the lower limit condition of the conditional expression (2) is not satisfied, it becomes difficult to achieve both the achromatism for the C-line and the F-line and the correction of the secondary spectrum. In addition, in order to achieve the achromatism for the C-line and the F-line, the refractive power of each lens increases, and hence it is difficult to maintain good optical performance. In another case, the number of lenses increases, and hence it becomes difficult to achieve a small size and light weight. The expression (2) is more preferred to satisfy the following conditional expression.

0.009<(1/νp−1/νap)/(φ1/φtele)<0.025 (17)

The conditional expression (3) defines a ratio between the refractive power φp of the positive lens Lp and the refractive power φ1 of the first lens unit, in order to achieve both the achromatism for the C-line and the F-line and the correction of the secondary spectrum at the telephoto end. If the upper limit condition of the conditional expression (3) is not satisfied, it becomes difficult to achieve the achromatism for the C-line and the F-line. In order to achieve the achromatism, the refractive power of each lens increases, and hence it becomes difficult to maintain good optical performance. In another case, the number of lenses increases, and hence it becomes difficult to achieve a small size and light weight. In addition, if the lower limit condition of the conditional expression (3) is not satisfied, the correction effect of the secondary spectrum is decreased.

The conditional expression (4) defines a relationship between the refractive power φp, and the average value of Abbe constants of the positive lenses except the positive lens Lp and the average value of Abbe constants of the negative lenses, in order to achieve both the achromatism for the C-line and the F-line and the correction of the secondary spectrum at the telephoto end. If the upper limit condition of the conditional expression (4) is not satisfied, the secondary spectrum correction effect is decreased. If the lower limit condition of the conditional expression (4) is not satisfied, the achromatism for the C-line and the F-line becomes difficult to achieve. In order to achieve the achromatism for the C-line and the F-line, the refractive power of each lens increases, and hence it becomes difficult to maintain good optical performance. In another case, the number of lenses increases, and hence it becomes difficult to achieve a small size and light weight. The conditional expression (4) is more preferred to satisfy the following conditional expression.

0.07<(1/νan−1/νap)/(φp/φ1)<0.50 (18)

The conditional expression (5) defines a ratio between the sum φn of refractive powers of negative lenses of the first lens unit and the refractive power φ1, in order to realize the achromatism for the C-line and the F-line and good optical performance. If the upper limit condition of the conditional expression (5) is not satisfied, it becomes difficult to realize good optical performance. In another case, the number of lenses increases, and hence it becomes difficult to achieve a small size and light weight. In addition, if the lower limit condition of the conditional expression (5) is not satisfied, the achromatism for the C-line and the F-line becomes difficult to achieve.

The conditional expression (6) and the conditional expression (7) define a relationship among the refractive power φp, the Abbe constant νp of the positive lens Lp, the sum φn of refractive powers of negative lenses of the first lens unit, and the average value νan of Abbe constants of the negative lenses of the first lens unit, in order to achieve both the achromatism for the C-line and the F-line and the correction of the secondary spectrum, and to realize good optical performance. If the upper limit condition of the conditional expression (6) is not satisfied, the achromatism for the C-line and the F-line becomes difficult to achieve. If the lower limit condition of the conditional expression (6) is not satisfied, the secondary spectrum correction effect is decreased. In another case, the refractive power of the negative lens is increased, and hence it becomes difficult to realize good optical performance. In still another case, the number of lenses increases, and hence it becomes difficult to achieve a small size and light weight.

In the conditional expression (7), if the value of νp is larger than the value of an so that the upper limit condition is not satisfied, the secondary spectrum correction effect is decreased. In addition, if the value of νp is smaller than the value of an so that the upper limit condition is not satisfied, the achromatism for the C-line and the F-line becomes difficult to achieve. The conditional expression (7) is more preferred to satisfy the following condition.

|νp−νan|<8 (19)

The conditional expression (8) defines a ratio between the refractive power φ2 of the second lens unit and the refractive power φp, in order to achieve both the high magnification ratio and the correction of the secondary spectrum.

If the upper limit condition of the conditional expression (8) is not satisfied, it becomes difficult to achieve the high magnification ratio. In addition, the focal length at the telephoto end decreases, and hence the secondary spectrum at the telephoto end can be corrected by a known method. In addition, if the lower limit condition of the conditional expression (8) is not satisfied, the refractive power of the second lens unit increases, and hence it becomes difficult to maintain good optical performance over the entire zoom range. In another case, the number of lenses increases, and hence it becomes difficult to achieve a small size and light weight.

In addition, some of the conditional expressions (1) to (8) use the average value for defining. If a lens having an extremely small refractive power like a flat glass plate is included, the range of the conditional expression may be exceeded. Therefore, it is supposed that using any number of lenses having an extremely small refractive power is included in the present invention.

[First Embodiment]

FIG. 3 is a cross sectional view of lenses at a wide angle end and in focus at an object distance of infinity according to Numerical Embodiment 1 as a first embodiment of the present invention. FIGS. 4A and 4B illustrate aberration diagrams at the wide angle end and the telephoto end, respectively, in focus at an object distance of 3 m according to Numerical Embodiment 1. In the aberration diagrams, a solid line indicates an e-line, a chain double-dashed line indicates a g-line, a dashed dotted line indicates a C-line, and a dotted line indicates an F-line. In addition, aspheric coefficients are denoted by A3 to A12. When a displacement in the optical axis direction at a position of a height H from the optical axis with reference to a surface vertex is denoted by x, the aspheric coefficients are expressed by the following expression.

$X = \frac{(1 / R) H^{2}}{1 + \sqrt{1 - (1 + K) {(H / R)}^{2}}} + A 3 \cdot H^{3} + A 4 \cdot H^{4} + A 5 \cdot H^{5} + A 6 \cdot H^{6} + A 7 \cdot H^{7} + A 8 \cdot H^{8} + A 9 \cdot H^{9} + A 10 \cdot H^{10} + A 11 \cdot H^{11} + A 12 \cdot H^{12}$

In this expression, a paraxial curvature radius is denoted by R, and a conic constant is denoted by K.

In FIG. 3, a front lens unit F has a positive refractive power as the first lens unit and does not move in the optical axis direction for magnification-varying. The first lens unit F includes a first sub lens unit that is disposed closest to the object side and does not move in the optical axis direction for focusing, and a second sub lens unit that is disposed on an image side and moves in the optical axis direction for focusing. A variator V as the second lens unit has a negative refractive power for magnification-varying and performs the magnification-varying from the wide angle end to the telephoto end by monotonously moving to the image plane side on the optical axis. A compensator C as the third lens unit has a negative refractive power and moves along the optical axis in a non-linear manner in order to correct image plane variation due to the magnification-varying. The variator V and the compensator C constitute the magnification-varying system. The zoom lens system further includes an aperture stop SP, and a relay lens unit R as the fourth lens unit, which has a positive refractive power for image formation action and does not move in the optical axis direction for the magnification-varying. The zoom lens system further includes a color separating prism or an optical filter P, which is illustrated as a glass block in FIG. 3, and an imaging plane I.

Next, the first lens unit according to this embodiment is described. The first lens unit corresponds to first to twelfth surfaces, and includes the first sub lens unit having the first to the sixth surfaces and the second sub lens unit having the seventh to the twelfth surfaces. The first sub lens unit includes, in order from the object side, a negative lens, a positive lens, and a positive lens. The second sub lens unit includes three positive lenses.

The positive lens having the smallest Abbe constant in the first lens unit is constituted of the fifth surface and the sixth surface.

Table 1 shows correspondence values of the conditional expressions in this embodiment.

This embodiment has a feature that the expressions (1), (4), (6), and (8) are close to the lower limit, the expression (3) is close to the upper limit, and an absolute value in the expression (7) is small.

This numerical embodiment satisfies all the conditional expressions, and hence achieves high magnification zoom, a small size, and light weight while appropriately correcting the longitudinal chromatic aberration at the telephoto end.

Note that in the following tables for the numerical embodiments, “e+xxx” and “e−xxx” represent “×10^xxx” and “×10^−xxx”, respectively.

(Numerical Embodiment 1)

Unit mm

Surface data

TABLE 1

Effec-

tive

Surface

diam-

Number
r
D
nd
vd
θgF
eter

1
−194.100
2.20
1.84666
23.8
0.621
74.53

2
92.143
4.52

71.87

3
104.970
8.46
1.43875
95.0
0.534
73.35

4
−1944.773
0.50

73.39

5
1583.212
7.77
1.84666
23.8
0.621
73.42

6
−141.639
6.16

73.40

7
147.739
6.95
1.43387
95.1
0.537
69.85

8
−419.036
0.15

69.37

9
87.704
9.18
1.43387
95.1
0.537
64.64

10
−323.707
0.15

63.68

11
44.477
7.43
1.43875
95.0
0.534
54.27

12
119.258
(Variable)

53.26

13
380.874
1.00
2.00330
28.3
0.598
18.01

14
12.885
4.49

14.88

15
−17.048
4.67
1.92286
18.9
0.650
14.56

16
−10.670
0.75
1.88300
40.8
0.567
15.07

17
−1970.510
0.30

16.16

18
48.341
5.22
1.62588
35.7
0.589
17.06

19
−19.189
0.93

17.80

20
−14.733
0.75
1.88300
40.8
0.567
17.79

21
−19.912
(Variable)

18.66

22
−24.069
0.75
1.75500
52.3
0.548
19.00

23
49.851
2.91
1.84649
23.9
0.622
20.90

24
−285.870
(Variable)

21.60

25 (Stop)
0.000
1.63

24.87

26
171.561
4.79
1.67003
47.2
0.563
26.40

27
−33.421
0.20

27.10

28
64.284
3.10
1.48749
70.2
0.530
27.90

29
−300.791
0.15

27.80

30
70.545
6.14
1.50127
56.5
0.554
27.50

31
−30.027
1.20
1.88300
40.8
0.567
27.10

32
−1145.653
32.00

27.10

33
72.712
6.34
1.49700
81.5
0.538
25.34

34
−37.239
0.47

24.92

35
−72.757
1.40
1.83403
37.2
0.578
23.92

36
23.509
6.38
1.48749
70.2
0.530
23.05

37
−416.047
2.67

23.30

38
59.003
6.54
1.50127
56.5
0.554
24.70

39
−25.474
1.40
1.88300
40.8
0.567
24.85

40
−62.880
1.40

25.78

41
45.276
4.82
1.50127
56.5
0.554
26.53

42
−66.169
4.00

26.37

43
0.000
33.00
1.60859
46.4
0.566
40.00

44
0.000
13.20
1.51633
64.2
0.535
40.00

45
0.000

40.00

Aspherical surface data

Thirteenth surface

K = −5.09201e+003
A4 = 4.00985e−005
A6 = −1.53470e−008

A8 = −4.42023e−009
A10 = −7.20166e−012
A12 = 5.37473e−014

A3 = −1.61689e−006
A5 = −1.92698e−006
A7 = 2.21125e−008

A9 = 4.06509e−010
A11 = −1.17225e−012

Various data

Zoom ratio 16.50

Wide angle
Intermediate
Telephoto

Focal length
8.00
32.48
132.00

F-number
1.88
1.88
2.50

Angle of Field
34.51
9.61
2.39

Image height
5.50
5.50
5.50

Total lens length
257.74
257.74
257.74

BF
7.53
7.53
7.53

d12
0.38
29.97
42.18

d21
38.50
4.88
0.77

d24
5.26
9.28
1.19

d45
7.53
7.53
7.53

Entrance pupil position
44.42
153.01
441.88

Exit pupil position
150.48
150.48
150.48

Front principal point position
52.86
192.87
695.77

Rear principal point position
−0.47
−24.95
−124.47

Zoom lens unit data

Lens

First
Focal
structure
Front principal
Rear principal

Unit
surface
length
length
point position
point position

1
1
56.43
53.48
31.41
−0.57

2
13
−12.86
18.11
−1.00
−16.56

3
22
−37.90
3.66
−0.26
−2.27

4
25
79.32
130.83
104.19
−181.87

[Second Embodiment]

FIG. 5 is a cross sectional view of lenses at the wide angle end and in focus at an object distance of infinity according to Numerical Embodiment 2 as a second embodiment of the present invention. FIGS. 6A and 6B illustrate aberration diagrams at the wide angle end and the telephoto end, respectively, in focus at an object distance of 3 m according to Numerical Embodiment 2. In the aberration diagrams, a full line indicates an e-line, a chain double-dashed line indicates a g-line, a dashed dotted line indicates a C-line, and a dotted line indicates an F-line.

In FIG. 5, a front lens unit F has a positive refractive power as the first lens unit and does not move in the optical axis direction for magnification-varying. The first sub lens unit 1a is a partial lens system disposed closest to the object side in the first lens unit F and does not move in the optical axis direction for focusing. The second sub lens unit 1b is a positive partial lens system disposed on the image side in the first lens unit F and moves for focusing. A variator V as the second lens unit has a negative refractive power for magnification-varying and performs the magnification-varying from the wide angle end to the telephoto end by monotonously moving to the image plane side on the optical axis. A compensator C as the third lens unit has a negative refractive power and moves along the optical axis in a non-linear manner in order to correct image plane variation due to the magnification-varying. The variator V and the compensator C constitute the magnification-varying system. The zoom lens system further includes an aperture stop SP, and a relay lens unit R as the fourth lens unit, which has a positive refractive power for image formation action and does not move in the optical axis direction for the magnification-varying. The zoom lens system further includes a color separating prism or an optical filter P, which is illustrated as a glass block in FIG. 5, and an imaging plane I.

Next, the first lens unit according to this embodiment is described. The first lens unit corresponds to the first to the twelfth surfaces, and includes the first sub lens unit having the first to the sixth surfaces and the second sub lens unit having the seventh to the twelfth surfaces. The first sub lens unit includes, in order from the object side, a negative lens, a positive lens, and a positive lens. The second sub lens unit includes three positive lenses.

The positive lens having the smallest Abbe constant in the first lens unit is constituted of the seventh surface and the eighth surface.

Table 1 shows correspondence values of the conditional expressions in this embodiment.

This embodiment has a feature that the expressions (1), (2), (4), (5), (6), and (8) are close to the upper limit, and that an absolute value in the expression (7) is relatively large.

(Numerical Embodiment 2)

Unit mm

Surface data

TABLE 2

Effec-

tive

Surface

diam-

Number
r
d
nd
vd
θgF
eter

1
−867.472
2.20
1.84666
23.8
0.603
74.10

2
100.879
7.11

70.89

3
629.150
5.70
1.43875
95.0
0.534
70.91

4
−195.176
0.50

70.86

5
450.431
7.74
1.43387
95.1
0.537
69.81

6
−158.575
6.42

69.33

7
282.092
3.76
1.94087
17.4
0.678
67.32

8
452.483
0.15

66.55

9
80.792
10.91
1.43387
95.1
0.537
64.50

10
−186.781
0.15

63.75

11
46.937
7.46
1.59240
68.3
0.546
55.16

12
136.421
(Variable)

54.21

13
401.840
1.00
1.88300
40.8
0.567
18.80

14
12.026
4.81

15.13

15
−18.763
4.97
1.88221
23.8
0.604
14.71

16
−10.338
0.75
1.88300
40.8
0.567
15.00

17
99.549
0.30

16.31

18
41.317
5.28
1.72047
34.7
0.583
17.17

19
−20.294
0.88

17.90

20
−15.709
0.75
1.88300
40.8
0.567
17.88

21
−22.799
(Variable)

18.71

22
−24.069
0.75
1.75500
52.3
0.548
19.00

23
49.851
2.91
1.84649
23.9
0.622
20.90

24
−285.870
(Variable)

21.60

25 (Stop)
0.000
1.63

24.93

26
308.351
4.85
1.67003
47.2
0.563
26.40

27
−30.391
0.20

27.10

28
54.847
3.30
1.48749
70.2
0.530
27.90

29
−428.917
0.15

27.80

30
122.029
5.93
1.50127
56.5
0.554
27.50

31
−27.054
1.20
1.88300
40.8
0.567
27.10

32
−262.878
31.99

27.10

33
64.444
5.80
1.49700
81.5
0.538
26.50

34
41.047
0.47

26.18

35
−236.331
1.40
1.83403
37.2
0.578
24.83

36
21.345
7.00
1.48749
70.2
0.530
23.45

37
118.392
2.67

23.35

38
50.359
6.56
1.50127
56.5
0.554
23.56

39
−25.864
1.40
1.88300
40.8
0.567
23.27

40
−72.216
1.40

23.95

41
45.399
4.30
1.50127
56.5
0.554
24.60

42
−66.452
4.00

24.48

43
0.000
33.00
1.60859
46.4
0.566
40.00

44
0.000
13.20
1.51633
64.2
0.535
40.00

45
0.000

40.00

Aspherical surface data

Thirteenth surface

K = −5.09201e+003
A4 = 4.01004e−005
A6 = −1.57839e−008

A8 = −4.42907e−009
A10 = −7.28656e−012
A12 = 5.14099e−014

A3 = −1.57792e−006
A5 = −1.927506−006
A7 = 2.20666e−008

A9 = 4.050206−010
A11 = −1.18440e−012

Various data

Zoom ratio 16.50

Wide angle
Intermediate
Telephoto

Focal length
8.00
32.48
132.00

F-number
1.87
1.87
2.50

Angle of Field
34.51
9.61
2.39

Image height
5.50
5.50
5.50

Total lens length
256.94
256.94
256.94

BF
7.53
7.53
7.53

d12
0.41
30.00
42.21

d21
38.81
5.19
1.08

d24
5.26
9.28
1.19

d45
7.53
7.53
7.53

Entrance pupil position
45.67
154.26
443.13

Exit pupil position
175.27
175.27
175.27

Front principal point
54.05
193.03
679.00

position

Rear principal point
−0.47
−24.95
−124.47

position

Zoom lens unit data

Lens

First
Focal
structure
Front principal
Rear principal

Unit
surface
length
length
point position
point position

1
1
56.43
52.09
32.66
−0.17

2
13
−12.86
18.74
−0.63
−16.25

3
22
−37.90
3.66
−0.26
−2.27

4
25
71.22
130.45
90.24
−162.52

[Third Embodiment]

FIG. 7 is a cross sectional view of lenses at a wide angle end and in focus at an object distance of infinity according to Numerical Embodiment 3 as a third embodiment of the present invention. FIGS. 8A and 8B illustrate aberration diagrams at the wide angle end and the telephoto end, respectively, in focus at an object distance of 3 m according to Numerical Embodiment 3. In the aberration diagrams, a full line indicates an e-line, a chain double-dashed line indicates a g-line, a dashed dotted line indicates a C-line, and a dotted line indicates an F-line.

In FIG. 7, a front lens unit F has a positive refractive power as the first lens unit and does not move in the optical axis direction for magnification-varying. The first sub lens unit 1a is a partial lens system 1a disposed closest to the object side in the first lens unit F and does not move in the optical axis direction for focusing. The second sub lens unit 1b is a positive partial lens system disposed on the image side in the first lens unit F and moves in the optical axis direction for focusing. A variator V as the second lens unit has a negative refractive power for magnification-varying and performs the magnification-varying from the wide angle end to the telephoto end by monotonously moving to the image plane side on the optical axis. A compensator C as the third lens unit has a negative refractive power and moves along the optical axis in a non-linear manner in order to correct image plane variation due to the magnification-varying. The variator V and the compensator C constitute the magnification-varying system. The zoom lens system further includes an aperture stop SP, and a relay lens unit R as the fourth lens unit, which has a positive refractive power for image formation action and does not move in the optical axis direction for the magnification-varying. The zoom lens system further includes a color separating prism or an optical filter P, which is illustrated as a glass block in FIG. 7, and an imaging plane I.

Next, the first lens unit according to this embodiment is described. The first lens unit corresponds to the first to the thirteenth surfaces, and includes the first sub lens unit having the first to the seventh surfaces and the second sub lens unit having the eighth to the thirteenth surfaces. The first sub lens unit includes, in order from the object side, a negative lens, a negative lens, a positive lens, and a positive lens. The second sub lens unit includes three positive lenses.

The positive lens having the smallest Abbe constant in the first lens unit is constituted of the sixth surface and the seventh surface.

Table 1 shows correspondence values of the conditional expressions in this embodiment.

This embodiment has a feature that the expression (5) is close to the lower limit, the expression (2) is close to the upper limit, and an absolute value in the expression (7) is relatively large.

(Numerical Embodiment 3)

Unit mm

Surface data

TABLE 3

Effec-

tive

Surface

diam-

Number
r
d
nd
vd
θgF
eter

1
−311.357
2.20
1.84666
23.8
0.621
73.25

2
149.755
2.59

70.86

3
229.221
2.20
1.84666
23.8
0.621
70.76

4
85.557
12.56
1.43875
95.0
0.534
69.44

5
−176.215
0.50

69.45

6
215.031
4.91
1.94087
17.4
0.678
68.72

7
1349.482
6.76

68.35

8
153.860
5.20
1.43387
95.1
0.537
67.45

9
−3649.480
0.15

67.07

10
89.290
9.53
1.43387
95.1
0.537
64.32

11
−244.511
0.15

63.53

12
56.462
6.18
1.75500
52.3
0.548
56.43

13
148.903
(Variable)

55.53

14
362.476
1.00
1.88300
40.8
0.567
20.67

15
12.455
5.86

16.54

16
−23.132
4.67
1.92286
18.9
0.650
15.74

17
−12.814
0.75
1.88300
40.8
0.567
15.97

18
123.434
0.30

16.46

19
39.242
4.73
1.65412
39.7
0.574
17.23

20
−26.843
1.20

17.79

21
−16.671
0.75
1.88300
40.8
0.567
17.79

22
−22.506
(Variable)

18.51

23
−24.069
0.75
1.75500
52.3
0.548
19.00

24
49.851
2.91
1.84649
23.9
0.622
20.90

25
−285.870
(Variable)

21.60

26 (Stop)
0.000
1.63

24.92

27
164.927
4.71
1.67003
47.2
0.563
26.40

28
−34.600
0.20

27.10

29
59.197
3.63
1.48749
70.2
0.530
27.90

30
−163.584
0.15

27.80

31
75.454
5.89
1.50127
56.5
03554
27.50

32
−31.119
1.20
1.88300
40.8
0.567
27.10

33
1000.656
32.00

27.10

34
69.168
6.29
1.49700
81.5
0.538
27.10

35
−37.293
0.47

24.78

36
−66.586
1.40
1.83403
37.2
0.578
23.84

37
24.164
6.83
1.48749
70.2
0.530
23.04

38
−433.599
2.67

23.89

39
56.136
6.23
1.50127
56.5
0.554
25.40

40
−27.775
1.40
1.88300
40.8
0.567
25.52

41
−63.618
1.40

26.34

42
39.020
4.31
1.50127
56.5
0.554
26.96

43
−109.144
4.00

26.78

44
0.000
33.00
1.60859
46.4
0.566
40.00

45
0.000
13.20
1.51633
64.2
0.535
40.00

46
0.000

40.00

Aspherical surface data

Fourteenth surface

K = −5.09201e+003
A4 = 4.01061e−005
A6 = −1.55724e−008

A8 = −4.42447e−009
A10 = −7.21946e−012
A12 = 5.26878e−014

A3 = −1.42185e−006
A5 = −1.92628e−006
A7 = 2.21013e−008

A9 = 4.05526e−010
A11 = −1.17668e−012

Various data

Zoom ratio 16.50

Wide angle
Intermediate
Telephoto

Focal length
8.00
32.48
132.00

F-number
1.88
1.88
2.50

Angle of Field
34.51
9.61
2.39

Image height
5.50
5.50
5.50

Total lens length
259.62
259.62
259.62

BF
7.52
7.52
7.52

d13
0.84
30.43
42.64

d22
39.52
5.91
1.79

d25
5.26
9.28
1.19

d46
7.52
7.52
7.52

Entrance pupil position
45.50
154.09
442.96

Exit pupil position
150.55
150.55
150.55

Front principal point position
53.95
193.95
696.79

Rear principal point position
−0.48
−24.96
−124.48

Zoom lens unit data

Lens

First
Focal
structure
Front principal
Rear principal

Unit
surface
length
length
point position
point position

1
1
56.43
52.94
32.50
0.93

2
14
−12.86
19.26
0.04
−15.54

3
23
−37.90
3.66
−0.26
−2.27

4
26
79.29
130.61
104.13
−181.80

[Fourth Embodiment]

FIG. 9 is a cross sectional view of lenses at a wide angle end and in focus at an object distance of infinity according to Numerical Embodiment 4 as a fourth embodiment of the present invention. FIGS. 10A and 10B illustrate aberration diagrams at the wide angle end and the telephoto end, respectively, in focus at an object distance of 13 m according to Numerical Embodiment 4. In the aberration diagrams, a full line indicates an e-line, a chain double-dashed line indicates a g-line, a dashed dotted line indicates a C-line, and a dotted line indicates an F-line.

In FIG. 9, a front lens unit F has a positive refractive power as the first lens unit and does not move in the optical axis direction for magnification-varying. The first sub lens unit 1a is a partial lens system disposed closest to the object side in the first lens unit F and does not move in the optical axis direction for focusing. The second sub lens unit 1b is a positive partial lens system disposed on the image side in the first lens unit F and moves in the optical axis direction for focusing. A variator V as the second lens unit has a negative refractive power for magnification-varying and performs the magnification-varying from the wide angle end to the telephoto end by monotonously moving to the image plane side on the optical axis. A compensator C as the third lens unit has a positive refractive power and moves along the optical axis in a non-linear manner in order to correct image plane variation due to the magnification-varying. The variator V and the compensator C constitute the magnification-varying system. The zoom lens system further includes an aperture stop SP, and a relay lens unit R as the fourth lens unit, which has a positive refractive power for image formation action and does not move in the optical axis direction for the magnification-varying. The zoom lens system further includes a color separating prism or an optical filter P, which is illustrated as a glass block in FIG. 9, and an imaging plane I.

The positive lens having the smallest Abbe constant in the first lens unit is constituted of the fifth surface and the sixth surface.

Table 1 shows correspondence values of the conditional expressions in this embodiment.

This embodiment is has a feature that an absolute value in the expression (7) is relatively large.

(Numerical Embodiment 4)

Unit mm

Surface data

TABLE 4

Effec-

tive

Surface

diam-

Number
r
d
nd
vd
θgF
eter

1
4725.734
5.00
1.84666
23.78
0.621
196.37

2
324.378
2.60

196.00

3
323.333
20.44
1.43387
95.1
0.537
197.60

4
−2112.308
0.20

198.02

5
734.527
10.19
1.94087
17.4
0.678
199.80

6
1890.502
29.03

199.57

7
409.103
18.04
1.43387
95.1
0.537
200.62

8
−2472.439
0.20

200.15

9
282.514
20.04
1.43387
95.1
0.537
195.65

10
13642.084
1.20

194.54

11
190.949
17.88
1.45600
90.33
0.534
181.52

12
410.214
(Variable)

178.18

13
495.839
3.34
1.88300
40.76
0.567
45.95

14
37.949
10.14

38.90

15
−47.944
1.40
1.75500
52.32
0.548
39.00

16
50.036
7.67
1.92286
18.9
0.650
43.88

17
−2116.056
0.38

44.65

18
−761.237
2.16
1.88300
40.76
0.567
44.76

19
4430.620
(Variable)

45.62

20
138.223
12.76
1.62041
60.29
0.543
80.65

21
−253.485
0.20

81.18

22
90.526
11.19
1.62041
60.29
0.543
82.02

23
580.574
0.20

81.07

24
100.649
2.30
1.76182
26.52
0.614
77.95

25
44.960
22.90
1.45600
90.33
0.534
70.68

26
−296.393
0.20

69.57

27
198.352
3.99
1.62041
60.29
0.543
66.90

28
280.602
(Variable)

65.36

29 (Stop)
0.000
2.12

30.56

30
−203.113
1.40
1.81600
46.62
0.557
29.62

31
42.004
0.20

28.52

32
35.010
4.09
1.84666
23.78
0.621
28.63

33
83.312
2.97

27.90

34
−68.919
1.40
1.88300
40.76
0.567
27.77

35
−114.243
7.96

27.83

36
−98.967
1.80
1.75500
52.32
0.548
26.47

37
38.793
4.40
1.80515
25.5
0.616
26.58

38
195.671
2.33

26.57

39
−461.129
14.17
1.60311
60.64
0.541
26.75

40
−150.247
7.75

27.97

41
−529.595
5.80
1.48749
70.23
0.530
28.21

42
−35.141
1.08

28.32

43
−40.105
1.60
1.88300
40.76
0.567
27.68

44
64.179
8.30
1.48749
70.23
0.530
28.50

45
−37.278
0.19

29.63

46
93.189
9.55
1.48749
70.23
0.530
29.86

47
−30.530
1.60
1.88300
40.76
0.567
30.04

48
−67.705
0.15

31.09

Aspherical surface data

Thirteenth surface

K = −3.78345e+002
A4 = 1.00185e−006
A6 = 5.92298e−009

A8 = −1.07010e−010
A10 = −4.83189e−013
A12 = −1.13291e−016

A3 = −7.31081e−007
A5 = −7.24884e−008
A7 = 2.42636e−010

A9 = 1.02311e−011
A11 = 1.16099e−014

Twenty-first surfaces

K = −1.14405e+001
A4 = −4.12140e−008
A6 = −5.50294e−011

A8 = 4.13936e−013
A10 = −2.42495e−016
A12 = −2.69997e−020

A3 = 3.47432e−007
A5 = 1.56395e−009
A7 = −6.31482e−012

A9 = −2.45242e−015
A11 = 5.08235e−018

Twenty-seventh surfaces

K = −1.23649e+001
A4 = −1.53197e−007
A6 = −2.07023e−010

A8 = −6.20327e−014
A10 = 2.00618e−015
A12 = 6.46068e−019

A3 = 6.470446−007
A5 = 4.24165e−010
A7 = 9.58159e−012

A9 = −2.42361e−014
A11 = −6.09256e−017

Various data

Zoom ratio 99.20

Wide angle
Intermediate
Telephoto

Focal length
9.70
70.06
962.21

F-number
1.87
1.87
4.90

Angle of Field
29.55
4.49
0.33

Image height
5.50
5.50
5.50

Total lens length
637.61
637.61
637.61

BF
8.01
8.01
8.01

d12
3.55
133.55
181.41

d19
272.31
120.13
1.90

d28
3.00
25.18
95.54

d53
8.01
8.01
8.01

Entrance pupil position
142.45
824.48
12587.94

Exit pupil position
216.36
216.36
216.36

Front principal point position
152.60
918.10
17993.92

Rear principal point position
−1.69
−62.05
−954.20

Zoom lens unit data

Lens

First
Focal
structure
Front principal
Rear principal

Unit
surface
length
length
point position
point position

1
1
249.09
124.82
68.21
−23.49

2
13
−26.53
25.10
5.50
−11.90

3
20
66.65
53.75
8.86
−27.35

4
29
44.40
147.08
56.67
11.30

[Fifth Embodiment]

FIG. 11 is a cross sectional view of lenses at the wide angle end and in focus at an object distance of infinity according to Numerical Embodiment 5 as a fifth embodiment of the present invention. FIGS. 12A and 12B illustrate aberration diagrams at the wide angle end and the telephoto end, respectively, in focus at an object distance of 13 m according to Numerical Embodiment 5. In the aberration diagrams, a full line indicates an e-line, a chain double-dashed line indicates a g-line, a dashed dotted line indicates a C-line, and a dotted line indicates an F-line.

In FIG. 11, a front lens unit F has a positive refractive power as the first lens unit and does not move in the optical axis direction for magnification-varying. The first sub lens unit 1a is a partial lens system disposed closest to the object side in the first lens unit F and does not move in the optical axis direction for focusing. The second sub lens unit 1b is a positive partial lens system disposed on the image side in the first lens unit F and moves in the optical axis direction for focusing. A variator V as the second lens unit has a negative refractive power for magnification-varying and performs the magnification-varying from the wide angle end to the telephoto end by monotonously moving to the image plane side on the optical axis. A compensator C as the third lens unit has a positive refractive power and moves along the optical axis in a non-linear manner in order to correct image plane variation due to the magnification-varying. The variator V and the compensator C constitute the magnification-varying system. The zoom lens system further includes an aperture stop SP, and a relay lens unit R as the fourth lens unit, which has a positive refractive power for image formation action and does not move in the optical axis direction for the magnification-varying. The zoom lens system further includes a color separating prism or an optical filter P, which is illustrated as a glass block in FIG. 11, and an imaging plane I.

Next, the first lens unit according to this embodiment is described. The first lens unit corresponds to the first to the twelfth surfaces, and includes the first sub lens unit having the first to the sixth surfaces and the second lens unit having the seventh to the twelfth surfaces. The first sub lens unit includes, in order from the object side, a negative lens, a positive lens, and a positive lens. The second sub lens unit includes three positive lenses.

The positive lens having the smallest Abbe constant in the first lens unit is constituted of the seventh surface and the eighth surface.

Table 1 shows correspondence values of the conditional expressions in this embodiment.

This embodiment has a feature that the expression (2) is close to the lower limit.

(Numerical Embodiment 5)

Unit mm

Surface data

TABLE 5

Effec-

tive

Surface

diam-

Number
r
D
nd
vd
θgF
eter

1
5069.860
5.00
1.84666
23.8
0.621
196.37

2
325.039
1.04

196.03

3
323.625
18.17
1.43387
95.1
0.537
196.70

4
−20136.695
0.20

197.13

5
549.795
17.84
1.43387
95.1
0.537
199.32

6
−1834.743
29.25

199.60

7
908.328
8.94
1.89000
19.2
0.662
200.31

8
26618.242
0.20

199.96

9
272.533
21.92
1.43387
95.1
0.537
196.76

10
−6500.318
1.20

195.77

11
181.670
21.07
1.43875
95.0
0.534
181.87

12
410.887
(Variable)

177.37

13
461.347
3.34
2.00330
28.3
0.598
45.20

14
40.835
9.35

38.93

15
−52.153
1.40
1.75500
52.3
0.548
39.04

16
48.774
8.82
1.92286
18.9
0.650
43.69

17
−164.616
0.33

44.33

18
−138.701
2.16
1.88300
40.8
0.567
44.34

19
1238.715
(Variable)

45.69

20
138.192
13.17
1.62041
60.3
0.543
80.61

21
−252.800
0.20

81.18

22
89.967
11.02
1.62041
60.3
0.543
81.92

23
513.793
0.20

80.95

24
96.398
2.30
1.76182
26.5
0.614
77.76

25
44.323
22.87
1.45600
90.3
0.534
70.37

26
−370.054
0.20

69.16

27
191.012
3.77
1.62041
60.3
0.543
66.71

28
280.823
(Variable)

65.31

29 (Stop)
0.000
1.76

30.58

30
−187.087
1.40
1.81600
46.6
0.557
29.89

31
41.687
0.20

28.79

32
34.858
3.85
1.84666
23.8
0.621
28.92

33
85.072
2.97

28.30

34
−73.508
1.40
1.88300
40.8
0.567
28.17

35
−109.354
7.50

28.20

36
−100.422
1.80
1.75500
52.3
0.548
26.73

37
38.657
4.57
1.80515
25.5
0.616
26.76

38
217.099
3.46

26.72

39
−399.945
15.22
1.60311
60.6
0.541
26.92

40
−196.132
9.53

27.96

41
−323.604
5.96
1.48749
70.2
0.530
28.21

42
−35.395
1.08

28.36

43
−41.677
1.60
1.88300
40.8
0.567
27.72

44
54.289
7.91
1.48749
70.2
0.530
28.53

45
−36.537
0.19

29.49

46
63.012
9.36
1.48749
70.2
0.530
30.07

47
−30.460
1.60
1.88300
40.8
0.567
30.14

48
−81.116
0.15

31.16

Aspherical surface data

Thirteenth surface

K = −2.86360e+002
A4 = 8.09315e−007
A6 = 6.66192e−009

A8 = −1.07787e−010
A10 = −4.82801e−013
A12 = −1.14295e−016

A3 = −7.81633e−007
A5 = −7.85780e−008
A7 = 2.27202e−010

A9 = 1.02677e−011
A11 = 1.16076e−014

Twenty-first surfaces

K = −9.70854e+000
A4 = −3.22022e−008
A6 = −6.22721e−011

A8 = 4.19895e−013
A10 = −2.5031e−016
A12 = −2.67289e−020

A3 = 2.95358e−007
A5 = 7.05297e−010
A7 = −5.82704e−012

A9 = −2.39260e−015
A11 = 5.10953e−018

Twenty-seventh surfaces

K = −1.37826e+001
A4 = −8.24180e−008
A6 = −2.07164e−010

A8 = 6.02187e−014
A10 = 1.94385e−015
A12 = 6.46986e−019

A3 = 6.02837e−007
A5 = −1.15214e−009
A7 = 7.90811e−012

A9 = −2.42701e−014
A11 = −6.06147e−017

Various data

Zoom ratio 99.20

Wide angle
Intermediate
Telephoto

Focal length
9.70
70.06
962.21

F-number
1.87
1.87
4.90

Angle of Field
29.55
4.49
0.33

Image height
5.50
5.50
5.50

Total lens length
639.60
639.60
639.60

BF
7.98
7.98
7.98

d12
2.95
132.95
180.81

d19
272.29
120.12
1.89

d28
3.00
25.18
95.54

d53
7.98
7.98
7.98

Entrance pupil position
141.49
823.49
12581.27

Exit pupil position
188.72
188.72
188.72

Front principal point position
151.71
920.71
18666.05

Rear principal point position
−1.72
−62.08
−954.23

Zoom lens unit data

Lens

First
Focal
structure
Front principal
Rear principal

Unit
surface
length
length
point position
point position

1
1
249.09
124.84
67.25
−24.52

2
13
−26.53
25.40
5.08
−11.99

3
20
66.65
53.73
8.79
−27.33

4
29
42.91
149.41
56.58
11.16

An image pickup apparatus is constituted of the zoom lens system according to any one of the above-mentioned embodiments, and a camera that is coupled to the zoom lens system for photographing a subject whose image is formed by the zoom lens system. Thus, it is possible to realize the image pickup apparatus that can appropriately correct the secondary spectrum of the longitudinal chromatic aberration on the telephoto side and can realize a small size and light weight.

The exemplary embodiments of the present invention are described above, but needless to say, the present invention is not limited to those embodiments, and various modifications and changes can be made thereto without departing from the spirit of the present invention.

TABLE 6

Table 1 correspondence values of conditional

expressions in Numerical Embodiments 1 to 5

Number of

conditional
Numerical
Numerical
Numerical
Numerical
Numerical

expression
Embodiment 1
Embodiment 2
Embodiment 3
Embodiment 4
Embodiment 5

(1)
0.000
0.123
0.092
0.092
0.067

(2)
0.013
0.020
0.020
0.012
0.011

(3)
0.370
0.073
0.211
0.199
0.067

(4)
0.085
0.423
0.143
0.158
0.132

(5)
−0.775
−0.534
−0.829
−0.611
−0.613

(6)
−0.478
−0.136
−0.254
−0.325
−0.389

(7)
0.000
6.380
6.380
6.380
4.630

(8)
−0.084
−0.017
−0.048
−0.021
−0.025

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2010-260974, filed Nov. 24, 2010, which is hereby incorporated by reference herein in its entirety.

Number	Name	Date	Kind
5737128	Usui	Apr 1998	A
6940656	Oomura et al.	Sep 2005	B2
7982971	Nakamura	Jul 2011	B2
8223224	Sakamoto	Jul 2012	B2
8223440	Wakazono et al.	Jul 2012	B2
20040169934	Oomura et al.	Sep 2004	A1
20120224270	Sakamoto	Sep 2012	A1

Number	Date	Country
0752605	Jan 1997	EP
9005628	Jan 1997	JP
2004264458	Sep 2004	JP

Zoom lens system

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

CPC

International Classifications

Term Extension

Abstract

Description

Claims

Priority Claims (1)

US Referenced Citations (7)

Foreign Referenced Citations (3)

Non-Patent Literature Citations (2)

Related Publications (1)

Entry
Gross, H ED “Handbook of Optical Systems, Chromatic Aberrations”, Jan. 1, 2007, pp. 268-289 XP002619942. Cited in EP EESR in counterpart appln. No. 11009065.1, dated Feb. 21, 2012.
Extended European Search Report issued in counterpart application No. EP11009065.1, dated Feb. 21, 2012.