JP7583572B2 - Zoom lens, and imaging device and imaging system having the same - Google Patents

Description

The present invention relates to a zoom lens, which is particularly suitable as an imaging optical system for use in imaging devices and imaging systems such as digital still cameras, video cameras, surveillance cameras, and broadcast cameras.

2. Description of the Related Art Imaging optical systems used in imaging devices such as surveillance cameras, digital cameras, and video cameras are required to have high optical performance capable of keeping up with the trend toward higher definition imaging elements.
Furthermore, in recent years, with the rapid expansion of the surveillance market, various demands have been made on the imaging optical systems for surveillance cameras.

Among such demands, for example, there is a growing demand for greater freedom in surveillance by enabling wide-area shooting with a single unit while achieving a high zoom ratio, as well as a demand for lightweight cameras for easier installation.
In addition, from the viewpoint of improving image quality, as the transition to 4K and 8K image quality is accelerating, there is also a demand for imaging optical systems with high optical performance capable of handling such high-definition imaging elements.

And, as disclosed in Patent Documents 1 and 2, for example, a positive-lead zoom lens in which the first lens group has positive refractive power is known as an imaging optical system with a high zoom ratio.

JP 2013-50519 A JP 2000-105336 A

Patent Document 1 discloses an example in which the refractive power of each lens group is positive, negative, positive, and positive, and the zoom ratio is about 30. In addition, the example shows a small-sized zoom lens having a high zoom ratio, but the optical performance is insufficient to support 4K and 8K image quality.
Furthermore, Patent Document 2 discloses an embodiment in which the refractive powers of the lens groups are positive, negative, positive, negative, positive, and the zoom ratio is about 40. Although the embodiment shows a zoom lens having a high zoom ratio and high optical performance, the overall lens length is too long.

That is, while the zoom lenses disclosed in Japanese Patent Application Laid-Open No. 2003-233693 and Japanese Patent Application Laid-Open No. 2003-233695 achieve a high zoom ratio, they are insufficient in terms of both achieving compactness and improved optical performance.
SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a zoom lens that is compact, has a high zoom ratio, and yet has high optical performance over the entire zoom range.

A zoom lens according to the present invention comprises, arranged in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear group including one or more lens groups, wherein the distance between adjacent lens groups changes during zooming, and the first lens group includes a positive lens made of a resin material, a first negative lens made of a resin material , and a second negative lens arranged closest to the object side , and the positive lens and the first negative lens are each spaced apart from their adjacent lenses, and when the refractive index and Abbe number of the positive lens for the d line are Ndp and νdp, the refractive index and Abbe number of the first negative lens for the d line are Ndn and νdn, and the refractive index of the second negative lens for the d line is Nd1 ,
Ndp<1.70
νdp<30.0
Ndn<1.70
νdn<30.0
Nd1>1.70
The present invention is characterized in that it satisfies the following conditions.

The present invention provides a zoom lens that is compact, has a high zoom ratio, and has high optical performance across the entire zoom range.

FIG. 2 is a lens cross-sectional view of the zoom lens according to the first embodiment at the wide-angle end. 5A to 5C are diagrams showing various aberrations of the zoom lens according to Example 1 at the wide-angle end, the intermediate zoom position, and the telephoto end. FIG. 11 is a lens sectional view of a zoom lens according to a second embodiment at a wide-angle end. 6A to 6C are diagrams showing various aberrations at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Example 2. FIG. 11 is a lens sectional view of a zoom lens according to a third embodiment at a wide-angle end. 11A to 11C are diagrams showing various aberrations at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Example 3. 1 is a diagram showing an example of an imaging apparatus having a zoom lens according to an embodiment of the present invention.

The zoom lens according to this embodiment will be described in detail below with reference to the accompanying drawings. Note that the drawings shown below may be drawn at a scale different from the actual scale in order to facilitate understanding of this embodiment.

The zoom lens according to this embodiment has the following features in order to have high optical performance over the entire zoom range while being small in size and having a high zoom ratio.
Specifically, the zoom lens according to this embodiment comprises, arranged in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a subsequent group (rear group) including one or more lens groups, and the spacing between each lens group changes when changing magnification from the wide-angle end to the telephoto end.

The first lens group includes at least one lens Pp (positive lens) having positive refractive power, and at least one lens Pn (first negative lens) having negative refractive power.
Each of the lenses Pp and Pn is made of a resin material, particularly plastic, and is spaced apart from the adjacent lenses.

Moreover, in the zoom lens according to this embodiment, the following conditional expressions (1), (2), (3) and (4) are satisfied.
Ndp<1.70...(1)
νdp<30.0...(2)
Ndn<1.70...(3)
νdn<30.0...(4)
Here, Ndp and νdp are the refractive index and Abbe number of the lens Pp for the d line, respectively. Also, Ndn and νdn are the refractive index and Abbe number of the lens Pn for the d line, respectively.

The zoom lens according to this embodiment has, in order from the object side to the image side, a lens group having positive refractive power, a lens group having negative refractive power, a lens group having positive refractive power, and a subsequent group, and is configured so that the spacing between each lens group changes when the magnification is changed.
This makes it possible to reduce the overall lens length and improve optical performance while maintaining a high zoom ratio.

Furthermore, by using a lens Pp formed from plastic that satisfies conditional expressions (1) and (2) in the first lens group, color differences such as axial chromatic aberration and spherical aberration can be well corrected on the telephoto side.
Furthermore, by positioning the lens Pp at a distance from adjacent lenses so that both sides of the lens Pp are in contact with air, both sides of the lens Pp can be made aspheric, thereby reducing spherical aberration on the telephoto side and astigmatism on the wide-angle side.

Furthermore, by using a lens Pn made of plastic that satisfies conditional expressions (3) and (4) in the first lens group, it is possible to correct the temperature defocus caused by the lens Pp.
Furthermore, by using a high dispersion material for the negative lens in the first lens group, primary chromatic aberration can be corrected satisfactorily.
Furthermore, by positioning the lens Pn at a distance from adjacent lenses so that both sides of the lens Pn are in contact with air, both sides of the lens Pn can be made aspheric, thereby reducing spherical aberration on the telephoto side and astigmatism on the wide-angle side.

In the zoom lenses according to the examples of this embodiment, the various elements are appropriately set so as to satisfy the above conditional expressions (1) to (4).
This makes it possible to obtain a zoom lens that is compact, has a high zoom ratio, and has high optical performance over the entire zoom range.

In the zoom lens according to this embodiment, it is preferable to set the numerical ranges of the conditional expressions (1) to (4) as shown in the following conditional expressions (1a) to (4a).
1.55<Ndp<1.69 (1a)
νdp<29.0...(2a)
1.55<Ndn<1.69 (3a)
νdn<29.0...(4a)

In the zoom lens according to this embodiment, it is more preferable to set the numerical ranges of the conditional expressions (1) to (4) as shown in the following conditional expressions (1b) to (4b).
1.60<Ndp<1.69 (1b)
νdp<27.0...(2b)
1.60<Ndn<1.69...(3b)
νdn<27.0...(4b)

It is preferable that the zoom lens according to this embodiment satisfies at least one of the following conditional expressions (5) to (9).
0.50<LDt/ft<1.00 (5)
-10.0<f1/f2<-4.0...(6)
5.0<fp/f1<100.0...(7)
-100.0<fn/f1<0.0...(8)
Nd1>1.70...(9)
Here, LDt is the total optical length (total lens length) of the zoom lens at the telephoto end, ft is the focal length of the zoom lens at the telephoto end, f1 is the focal length of the first lens group, and f2 is the focal length of the second lens group. Note that the total optical length here is defined as the value obtained by adding the back focus value in air equivalent to the distance from the first lens surface to the final lens surface.
Furthermore, fp is the focal length of the lens Pp, fn is the focal length of the lens Pn, and Nd1 is the refractive index for the d-line of the negative lens Gn1 (second negative lens) arranged closest to the object in the first lens group.

Conditional expression (5) defines the ratio between the total optical length at the telephoto end of the zoom lens and the focal length at the telephoto end.
If the upper limit of condition (5) is exceeded, the overall length of the zoom lens becomes too long, which is undesirable.
On the other hand, if the lower limit of conditional expression (5) is not reached, it becomes difficult to correct spherical aberration and axial chromatic aberration at the telephoto end, which is undesirable.

Condition (6) defines the ratio of the focal length of the first lens group to the focal length of the second lens group.
If the upper limit of condition (6) is exceeded, large spherical aberration and coma will occur in the first lens group, which is undesirable.
On the other hand, if the lower limit of condition (6) is not reached, the fluctuations in aberrations such as field curvature and spherical aberration caused by zooming become large, which is undesirable.

Condition (7) defines the ratio between the focal length of the lens Pp and the focal length of the first lens group.
If the upper limit of condition (7) is exceeded, the power (refractive power) of the lens Pp becomes too weak, making it difficult to correct color differences such as axial chromatic aberration and spherical aberration on the telephoto side, which is undesirable.
On the other hand, if the lower limit of conditional expression (7) is not reached, the power of the lens Pp becomes too strong, and the focus deviation of the lens Pp when the temperature changes becomes too large, which is not preferable.

Condition (8) defines the ratio between the focal length of the lens Pn and the focal length of the first lens group.
If the upper limit value of conditional expression (8) is exceeded, the power of the lens Pn becomes too weak, making it difficult to correct color differences such as axial chromatic aberration and spherical aberration on the telephoto side, which is undesirable.
On the other hand, if the lower limit of conditional expression (8) is not reached, the power of the lens Pn becomes too strong, and the focus deviation of the lens Pn when the temperature changes becomes too large, which is not preferable.

Conditional expression (9) defines the refractive index for the d-line of the negative lens Gn1 that is disposed closest to the object side in the first lens group.
If the lower limit of condition (9) is exceeded, the refractive index of the negative lens Gn1 for the d-line becomes too small, so that the radius of curvature of the negative lens Gn1 becomes small, and it becomes difficult to ensure the edge thickness when cemented with a positive lens, which is not preferable.

In the zoom lens according to this embodiment, it is preferable to set the numerical ranges of the conditional expressions (5) to (9) as shown in the following conditional expressions (5a) to (9a).
0.60<LDt/ft<1.00...(5a)
-10.0<f1/f2<-6.0...(6a)
8.0<fp/f1<80.0...(7a)
-80.0<fn/f1<-5.0...(8a)
Nd1>1.75...(9a)

Furthermore, in the zoom lens according to this embodiment, it is more preferable to set the numerical ranges of the conditional expressions (5) to (9) as shown in the following conditional expressions (5b) to (9b).
0.70<LDt/ft<1.00...(5b)
-8.0<f1/f2<-6.0...(6b)
10.0<fp/f1<60.0...(7b)
-60.0<fn/f1<-7.0...(8b)
Nd1>1.80...(9b)

In the zoom lens according to this embodiment, it is preferable to place the aperture stop on the image side of the second lens group.
By locating the aperture stop on the image side of the second lens group, which has a strong negative power because it becomes the main magnification group, it is possible to suppress an increase in the effective diameter of the lens group located on the image side of the second lens group, and it is possible to achieve a reduction in the size and weight of the entire system.

It is also preferable that the aperture stop be fixed relative to the image plane during zooming from the wide-angle end to the telephoto end.
If the aperture stop moves in the optical axis direction during magnification change, this leads to a complicated mechanism and an increase in the diameter of the lens unit, which is not preferable.

It is preferable that at least one surface of each of the lenses Pn and Pp is aspheric.
This makes it possible to satisfactorily correct coma aberration on the telephoto side and astigmatism on the wide-angle side.

It is also preferable that at least the second lens group and the lens group disposed closest to the image side move when changing magnification from the wide-angle end to the telephoto end.
This makes it possible to efficiently obtain a desired zoom ratio in the second lens group, while at the same time making it possible to correct fluctuations in curvature of field and lateral chromatic aberration that accompany zooming in the lens group disposed closest to the image side.

It is also preferable that at least three lens groups move when changing magnification from the wide-angle end to the telephoto end.
This makes it possible to reduce the size of the entire system and achieve a high zoom ratio while suppressing fluctuations in various aberrations during zooming.

It is preferable that the lens group disposed closest to the image side has at least one lens having negative refractive power and at least one lens having positive refractive power.
This makes it possible to reduce the field curvature and astigmatism on the telephoto side.

In the zoom lens according to each example of this embodiment, by configuring each element as described above, it is possible to achieve high optical performance over the entire zoom range while being small in size and having a high zoom ratio.
Moreover, by arbitrarily combining a plurality of the above conditional expressions, the effect of this embodiment can be further improved.

The zoom lens according to each example of this embodiment is an imaging optical system used in imaging devices such as digital still cameras, video cameras, silver halide film cameras, and television cameras.
1, 3 and 5 are lens sectional views at the wide-angle end of zoom lenses according to Examples 1, 2 and 3, respectively, with the left and right sides being the object side and the image side, respectively.

As shown in FIG. 1, the zoom lens of Example 1 includes a first lens unit L1 having positive refractive power, a second lens unit L2 having negative refractive power, a third lens unit L3 having positive refractive power, and a fourth lens unit L4 having positive refractive power.
As shown in FIG. 3, the zoom lens of Example 2 includes a first lens unit L1 having positive refractive power, a second lens unit L2 having negative refractive power, a third lens unit L3 having positive refractive power, and a fourth lens unit L4 having positive refractive power.
As shown in FIG. 5, the zoom lens of Example 3 includes a first lens group L1 having positive refractive power, a second lens group L2 having negative refractive power, a third lens group L3 having positive refractive power, a fourth lens group L4 having negative refractive power, and a fifth lens group L5 having positive refractive power.

In addition, in Figures 1, 3, and 5, I is an image plane, and when a zoom lens is used as an imaging optical system of a digital still camera or a video camera, the image plane I corresponds to a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor.
On the other hand, when a zoom lens is used as the imaging optical system of a silver halide film camera, the image plane I corresponds to the film plane.

The arrows in FIGS. 1, 3 and 5 indicate the movement locus of each lens group during zooming.
1, 3 and 5, SP denotes an aperture stop, and the opening diameter of the aperture stop SP can be constant or can be changed during zooming.
By changing the diameter of the aperture stop SP, it is possible to cut off the underline coma flare caused by off-axis light beams that occurs significantly at the telephoto end, thereby obtaining better optical performance.

Moreover, focusing is performed by moving at least one lens group along the optical axis.
Of the movement loci of the focus group depicted in Figures 1, 3, and 5, the curves drawn with solid lines indicate movement loci for correcting image plane fluctuations that occur when zooming from the wide-angle end to the telephoto end when focusing on an object at infinity.
The curved dotted line indicates the movement locus for correcting the image plane fluctuation that occurs with zooming from the wide-angle end to the telephoto end when focusing on a close-up object.

In the zoom lenses according to the examples of this embodiment, focusing is not limited to being performed by one lens group, but may be performed by moving multiple lens groups along the optical axis.

2A, 2B, and 2C are diagrams showing various aberrations of the zoom lens according to Example 1 at the wide-angle end, at the intermediate zoom position, and at the telephoto end, respectively.
4A, 4B, and 4C show diagrams of various aberrations of the zoom lens according to Example 2 at the wide-angle end, at the intermediate zoom position, and at the telephoto end, respectively.
6A, 6B, and 6C are diagrams showing various aberrations of the zoom lens according to Example 3 at the wide-angle end, at the intermediate zoom position, and at the telephoto end, respectively.

In the spherical aberration diagram, Fno indicates the F-number, the solid line indicates the d-line (wavelength 587.56 nm), the two-dot chain line indicates the g-line (wavelength 435.84 nm), the one-dot chain line indicates the C-line (wavelength 656.27 nm), and the dashed line indicates the F-line (wavelength 486.13 nm).
In the astigmatism diagram, the solid line indicates the sagittal image surface at the d-line, and the broken line indicates the meridional image surface at the d-line.
Distortion is shown for the d-line, and the lateral chromatic aberration diagram shows aberrations for the g-line, C-line, and F-line relative to the d-line.
In the diagrams showing astigmatism, distortion, and lateral chromatic aberration, ω indicates the imaging half angle of view.

Next, an example of an image pickup apparatus using the zoom lens according to this embodiment as an image pickup optical system will be described with reference to FIG.
As shown in FIG. 7, a surveillance camera body 10, which is an imaging device, is provided with an imaging optical system 11 constituted by a zoom lens according to any one of the first to third embodiments.

The surveillance camera body 10 also incorporates a solid-state image sensor (photoelectric conversion element) 12 such as a CCD sensor or a CMOS sensor that receives a subject image formed by the imaging optical system 11 .
The surveillance camera body 10 also has a memory 13 that records information corresponding to the subject image photoelectrically converted by the solid-state imaging element 12, and a network cable 14 for transferring the subject image photoelectrically converted by the solid-state imaging element 12.

The imaging device in which the zoom lens according to this embodiment is used is not limited to a surveillance camera, and the zoom lens according to this embodiment can also be used in video cameras, digital cameras, etc.

Moreover, an imaging device in which the zoom lens according to this embodiment is used may further be provided with a circuit that electrically corrects at least one of distortion and lateral chromatic aberration.
By providing such a circuit and making it possible to allow for distortion and other aberrations of the zoom lens, the number of lenses in the entire zoom lens can be reduced, facilitating miniaturization.
Furthermore, by electrically correcting lateral chromatic aberration, color bleeding in a photographed image can be reduced, making it easy to improve resolution.

The zoom lens according to this embodiment is not limited to the above, and various modifications and variations are possible within the scope of the gist.

Next, Numerical Examples 1 to 3 corresponding to Examples 1 to 3 of this embodiment, respectively, are shown.
In each numerical example, i indicates the order of the optical surface from the object side, ri indicates the radius of curvature of the i-th optical surface (i-th surface), and di indicates the distance between the i-th surface and the (i+1)-th surface.
In each numerical example, Ndi and νdi respectively indicate the refractive index and Abbe number of the material of the optical member between the ith surface and the (i+1)th surface with respect to the d-line.
In each numerical example, BF (back focus) is the distance from the final lens surface excluding the filter to the paraxial image surface expressed as an air-equivalent length, and * indicates an aspheric surface.

The Abbe number of the optical material used in each example is given by the following formula (10).
νd=(Nd-1)/(NF-NC)...(10)
Here, NF, Nd and NC are the refractive indices of the optical material for the F line (486.1 nm), d line (587.6 nm) and C line (656.3 nm) of the Fraunhofer lines, respectively.

のように表される。 In addition, when k is the eccentricity, R is the paraxial radius of curvature, A4, A6, A8, A10, and A12 are aspheric coefficients, and X is the displacement in the optical axis direction at a position of height h from the optical axis based on the surface vertex, the aspheric shape is expressed as follows:

It can be expressed as follows.

The correspondence between each numerical example and the above conditional expressions is shown in Table 1 below.

[Numerical Example 1]
Unit: mm

Surface data surface number i ri di Ndi νdi
1 84.491 1.72 2.00069 25.5
2 50.394 3.27 1.43700 95.1
3 127.406 0.17
4* 69.658 1.53 1.68040 18.1
5* 83.000 0.17
6 47.925 4.07 1.43700 95.1
7 344.542 0.17
8* 41.594 1.41 1.61550 25.9
9* 40.152 0.17
10 35.680 4.83 1.49700 81.5
11 382.652 (variable)
12 310.076 0.63 2.05090 26.9
13 8.802 3.21
14 -37.587 0.60 1.49700 81.5
15 25.877 1.73
16 -18.932 0.60 1.88300 40.8
17 186.825 0.17
18 31.722 2.41 1.92286 18.9
19 -26.151 (variable)
20(Aperture) ∞ 1.74
21* 11.862 3.85 1.49710 81.6
22* -44.603 4.07
23 12.199 1.00 1.98030 21.5
24 8.752 2.00
25∞0.00
26 ∞ (variable)
27* 14.713 4.50 1.49700 81.5
28 -13.952 1.00 1.84666 23.8
29 -22.422 9.98
Image plane ∞

Aspheric data No. 4
K = 3.30573e+000 A 4= 1.93630e-006 A 6= 1.34714e-009

Page 5
K = 4.16190e+000 A 4= 1.68642e-006 A 6= 2.13323e-009

Side 8
K = 6.01790e-001 A 4= 1.63013e-006 A 6=-2.79068e-009

Page 9
K = 8.78573e-001 A 4= 2.94925e-006 A 6=-3.34975e-009

Page 21
K =-8.48568e-001 A 4=-1.71826e-006 A 6= 1.31810e-007 A 8=-2.05967e-009
A16=-3.21341e-016

Page 22
K = 2.77052e+000 A 4= 2.95084e-005 A 6= 3.58121e-008 A 8=-2.41959e-009
A16=-3.75217e-016

Page 27
K =-1.62263e+000 A 4= 4.36938e-005 A 6= 8.37393e-008 A 8=-1.29534e-009
A16 = 1.30626e-015

Various data zoom ratio 30.00

Focal length 4.67 39.38 140.18
F-number 2.06 4.06 4.64
Half angle of view 35.23 4.79 1.35
Image height 3.30 3.30 3.30
Lens length 109.92 109.92 109.92
BF 9.98 19.47 7.36

d11 0.78 30.70 38.17
d19 42.58 7.72 1.74
d26 11.57 7.03 17.64
d29 9.98 19.47 7.36

Zoom lens data group Starting surface Focal length
1 1 54.22
2 12 -8.12
3 20 27.53
4 27 22.24

[Numerical Example 2]
Unit: mm

Surface data surface number i ri di Ndi νdi
1 92.541 1.72 2.00069 25.5
2 53.143 4.92 1.43700 95.1
3 -1119.107 0.17
4 67.412 1.50 1.68040 18.1
5 79.584 0.17
6 54.219 3.22 1.49700 81.5
7 249.244 0.17
8 37.281 1.36 1.61550 25.9
9 35.190 0.17
10 36.543 3.64 1.49700 81.5
11 126.428 (variable)
12 463.521 0.63 2.05090 26.9
13 10.617 2.06
14 100.408 0.60 1.49700 81.5
15 10.460 2.92
16 -17.991 0.60 1.88300 40.8
17 146.854 0.17
18 27.503 2.32 1.92286 18.9
19 -31.262 (variable)
20(Aperture) ∞ 1.74
21* 11.487 3.76 1.49710 81.6
22* -39.852 3.48
23 12.725 1.00 1.99168 23.7
24 8.833 2.00
25∞0.00
26 ∞ (variable)
27* 15.320 4.50 1.49700 81.5
28 -13.431 1.00 1.84666 23.8
29 -21.176 9.98
Image plane ∞

Aspheric data No. 21
K =-8.83782e-001 A 4= 2.20713e-006 A 6= 3.69395e-008 A 8= 1.21143e-009
A16=-3.21341e-016

Page 22
K = 9.49884e-001 A 4= 3.41000e-005 A 6=-4.56168e-008 A 8= 6.38958e-010
A16=-3.75217e-016

Page 27
K =-6.15364e-001 A 4= 2.24939e-006 A 6= 8.66479e-008 A 8=-1.68035e-009
A16 = 1.30626e-015

Various data zoom ratio 30.00

Focal length 4.82 40.93 144.62
F-number 2.06 4.06 4.64
Half angle of view 34.39 4.61 1.31
Image height 3.30 3.30 3.30
Lens total length 109.99 109.99 109.99
BF 9.98 20.01 7.30

d11 0.96 31.53 39.17
d19 42.46 7.46 1.73
d26 12.76 7.16 17.96
d29 9.98 20.01 7.30

Zoom lens data group Starting surface Focal length
1 1 55.50
2 12 -8.15
3 20 27.44
4 27 22.30

[Numerical Example 3]
Unit: mm

Surface data surface number i ri di Ndi νdi
1 100.399 1.72 2.00069 25.5
2 75.156 4.15 1.43700 95.1
3 -216.152 0.17
4* 113.850 1.40 1.61550 25.9
5* 76.815 0.17
6 55.723 2.93 1.43700 95.1
7 711.813 0.17
8 54.487 1.21 1.68040 18.1
9 55.407 0.17
10 30.741 3.19 1.43700 95.1
11 99.866 (variable)
12 781.146 0.63 2.05090 26.9
13 12.319 2.31
14 -36.827 0.60 1.49700 81.5
15 10.790 2.34
16 -23.714 0.60 1.85481 56.8
17 380.297 0.40
18 27.460 2.45 1.92286 18.9
19 -52.691 (variable)
20(Aperture) ∞ 0.60
21* 12.843 3.04 1.43700 95.1
22* -29.621 (variable)
23 12.539 1.00 1.90674 18.0
24 9.778 2.00
25∞0.00
26 ∞ (variable)
27* 13.466 3.32 1.49700 81.5
28 -13.089 1.00 1.84666 23.8
29 -20.433 10.00
Image plane ∞

Aspheric data No. 4
K = 1.01403e+001 A 4=-4.49071e-007 A 6= 1.69846e-008 A 8=-6.66244e-011
A10= 6.96333e-014

Page 5
K =-4.15353e-001 A 4= 7.59074e-007 A 6= 1.92592e-008 A 8=-7.41996e-011
A10= 7.97459e-014

Page 21
K =-7.24678e-001 A 4=-2.01832e-005 A 6= 1.83547e-007 A 8=-3.92900e-010
A16=-3.21341e-016

Page 22
K =-6.70695e+000 A 4=-6.15844e-007 A 6= 2.19064e-007 A 8=-9.28580e-010 A16=-3.75217e-016

Page 27
K =-1.35089e+000 A 4= 1.57910e-005 A 6= 3.81085e-007 A 8=-7.25708e-009
A16 = 1.30626e-015

Various data zoom ratio 21.00

Focal length 5.00 45.24 105.00
F-number 2.06 4.06 4.64
Half angle of view 33.42 4.17 1.80
Image height 3.30 3.30 3.30
Lens total length 100.00 100.00 100.00
BF 10.00 20.99 10.22

d11 0.99 29.48 36.61
d19 35.62 1.95 0.50
d22 5.08 8.10 6.27
d26 12.76 3.92 10.85
d29 10.00 20.99 10.22

Zoom lens data group Starting surface Focal length
1 1 52.91
2 12 -8.00
3 20 20.96
4 23 -59.16
5 27 19.94

[Imaging system]
Moreover, an imaging system (surveillance camera system) may be configured that includes the zoom lens of each embodiment and a control unit that controls the zoom lens.
In this case, the control unit can control the zoom lens so that each lens group moves as described above during zooming and focusing.

In this case, the control unit does not need to be configured integrally with the zoom lens, and the control unit may be configured separately from the zoom lens.
For example, a configuration may be adopted in which a control unit (control device) disposed remotely from a drive unit that drives each lens of a zoom lens includes a transmission unit that sends a control signal (command) for controlling the zoom lens.
Such a control unit allows the zoom lens to be remotely controlled.

In addition, a configuration may be adopted in which an operation unit such as a controller or buttons for remotely operating the zoom lens is provided in the control unit, so that the zoom lens is controlled in response to a user's input to the operation unit.
For example, the operation unit may be provided with a zoom-in button and a zoom-out button, and a signal may be sent from the control unit to the zoom lens drive unit so that when the user presses the zoom-in button, the magnification of the zoom lens increases, and when the user presses the zoom-out button, the magnification of the zoom lens decreases.

The imaging system may also have a display unit such as a liquid crystal panel that displays information (movement state) related to the zoom of the zoom lens.
The information relating to the zoom of the zoom lens is, for example, the zoom magnification (zoom state) and the amount of movement (movement state) of each lens group.
In this case, the user can remotely operate the zoom lens via the operation unit while viewing information related to the zoom of the zoom lens displayed on the display unit.
In this case, the display unit and the operation unit may be integrated by using, for example, a touch panel.

L1: first lens group L2: second lens group L3: third lens group L4: fourth lens group (rear group)
L5 Fifth lens group (rear group)

Claims (21)

the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, and a rear group including one or more lens groups, arranged in this order from the object side to the image side;
When zooming, the spacing between adjacent lens groups changes.
the first lens group includes a positive lens made of a resin material, a first negative lens made of a resin material , and a second negative lens disposed closest to the object side ;
the positive lens and the first negative lens are each spaced apart from an adjacent lens;
When the refractive index and Abbe number of the positive lens for the d line are Ndp and νdp, the refractive index and Abbe number of the first negative lens for the d line are Ndn and νdn, and the refractive index of the second negative lens for the d line is Nd1 ,
Ndp<1.70
νdp<30.0
Ndn<1.70
νdn<30.0
Nd1>1.70
A zoom lens that satisfies the following conditions. When the total optical length and focal length of the zoom lens at the telephoto end are LDt and ft, respectively,
0.50<LDt/ft<1.00
2. The zoom lens according to claim 1, which satisfies the following condition: When the focal lengths of the first lens group and the second lens group are f1 and f2, respectively,
-10.0<f1/f2<-4.0
3. The zoom lens according to claim 1, wherein the following condition is satisfied: When the focal lengths of the first lens group and the positive lens are f1 and fp, respectively,
5.0<fp/f1<100.0
4. The zoom lens according to claim 1, wherein the following condition is satisfied: When the focal lengths of the first lens group and the first negative lens are f1 and fn, respectively,
-100.0<fn/f1<0.0
5. The zoom lens according to claim 1, which satisfies the following condition: The zoom lens according to any one of claims 1 to 5, characterized in that it has an aperture stop arranged on the image side of the second lens group. The zoom lens according to claim 6, characterized in that the aperture diaphragm is fixed relative to the image plane when changing magnification from the wide-angle end to the telephoto end. The zoom lens according to any one of claims 1 to 7, characterized in that at least one surface of each of the positive lens and the first negative lens is aspheric. The zoom lens according to any one of claims 1 to 8, characterized in that, when changing magnification from the wide-angle end to the telephoto end, the second lens group and the lens group arranged closest to the image side move. The zoom lens according to any one of claims 1 to 9, characterized in that the lens group arranged closest to the image side includes at least one negative lens and at least one positive lens. 11. The zoom lens according to claim 1, wherein at least three lens groups move when changing magnification from the wide-angle end to the telephoto end. 12. The zoom lens according to claim 1, wherein the rear group is a fourth lens group having a positive refractive power. 12. The zoom lens according to claim 1, wherein the rear group comprises, in order from the object side to the image side, a fourth lens group having a negative refractive power and a fifth lens group having a positive refractive power. the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, and a rear group including one or more lens groups, arranged in this order from the object side to the image side;
When zooming, the spacing between adjacent lens groups changes.
the first lens group includes a positive lens made of a resin material and a first negative lens made of a resin material,
the positive lens and the first negative lens are each spaced apart from an adjacent lens;
The refractive index and Abbe number of the positive lens for the d line are Ndp and νdp, the refractive index and Abbe number of the first negative lens for the d line are Ndn and νdn, the focal length of the first lens group is f1, and the focal length of the positive lens is fp.
Ndp<1.70
νdp<30.0
Ndn<1.70
νdn<30.0
5.0<fp/f1<100.0
A zoom lens that satisfies the following conditions. the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, and a rear group including one or more lens groups, arranged in this order from the object side to the image side;
During magnification change, at least three lens groups move and the spacing between adjacent lens groups changes;
the first lens group includes a positive lens made of a resin material and a first negative lens made of a resin material,
the positive lens and the first negative lens are each spaced apart from an adjacent lens;
When the refractive index and Abbe number of the positive lens for the d line are Ndp and νdp, respectively, and the refractive index and Abbe number of the first negative lens for the d line are Ndn and νdn, respectively,
Ndp<1.70
νdp<30.0
Ndn<1.70
νdn<30.0
A zoom lens that satisfies the following conditions. the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, and a rear group including one or more lens groups, arranged in this order from the object side to the image side;
When zooming, the spacing between adjacent lens groups changes.
the first lens group includes a positive lens made of a resin material and a first negative lens made of a resin material,
the positive lens and the first negative lens are each spaced apart from an adjacent lens;
the rear group includes, in order from the object side to the image side, a fourth lens group having a negative refractive power and a fifth lens group having a positive refractive power;
When the refractive index and Abbe number of the positive lens for the d line are Ndp and νdp, respectively, and the refractive index and Abbe number of the first negative lens for the d line are Ndn and νdn, respectively,
Ndp<1.70
νdp<30.0
Ndn<1.70
νdn<30.0
A zoom lens that satisfies the following conditions. 17. An imaging apparatus comprising: the zoom lens according to claim 1; and an imaging element that receives an image formed by the zoom lens. 17. An imaging system comprising: a zoom lens according to claim 1; and a control unit that controls the zoom lens during zooming. 20. The imaging system according to claim 18 , wherein the control unit is configured as a separate unit from the zoom lens, and includes a transmission unit that transmits a control signal for controlling the zoom lens. 20. The imaging system according to claim 18 , wherein the control unit is configured as a separate unit from the zoom lens, and has an operation unit for operating the zoom lens. 21. The imaging system according to claim 18, further comprising a display unit that displays information related to the zoom of the zoom lens.

Images