JP2012194238A - Zoom optical system and imaging apparatus with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom optical system that has a large half field angle at a wide angle end and a large variable power ratio toward a telephoto end, and an imaging apparatus with the same.SOLUTION: The zooming optical system comprises, in order from an object side to an image side, a first lens group G1 of negative refractive power, a second lens group G2 of positive refractive power, and a third lens group G3 of positive refractive power. To zoom, at least the first and second lens groups G1 and g2 are moved. The interval between the first and second lens groups G1 and G2 is narrower at the telephoto end than that at the wide angle and. The lens groups are moved so as to increase the interval between the second and third lens groups G2 and G3. The first lens group G1 includes, in order from the object side to the image side, a negative meniscus lens L11 whose convex face is oriented toward an object side, and a negative lens L12. The zoom optical system has a half field angle of 90° or more at the wide angle end. The zoom optical system satisfies 2<ft/fw if its focal distance at the wide angle end is fw and its focal distance at the telephoto end is ft.

Description

  The present invention relates to a zoom optical system having a large zoom ratio and a wide angle of view. Furthermore, the present invention relates to an imaging apparatus provided with a zoom optical system.

  2. Description of the Related Art Conventionally, zoom lenses that change the magnification from a wide-angle lens to a telephoto side have been disclosed.

Japanese Patent No. 3315839 Japanese Patent No. 3709000 JP-A-8-171053 JP 2007-94371 A JP 2009-103790 A JP 2009-271165 A

  However, the zoom lenses disclosed in Patent Documents 1 to 6 have a small zoom ratio, and the function as a zoom lens is not sufficient.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a zoom optical system having a large half angle of view at the wide-angle end and a large zoom ratio to the telephoto end. . Furthermore, it aims at providing the imaging device provided with such a zoom optical system.

  In order to solve the above problems, a zoom optical system according to the present invention is as follows.

The zoom optical system includes, in order from the object side to the image side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. Zooming is performed by moving the first lens group and the second lens group, and the distance between the first lens group and the second lens group at the telephoto end is smaller than at the wide-angle end, and the first lens group at the telephoto end is smaller than at the wide-angle end. The first lens group includes, in order from the object side to the image side, a negative meniscus lens having a convex surface facing the object side, and a negative lens so that the distance between the second lens group and the third lens group is increased. It has a half angle of view of 90 ° or more at the wide-angle end, and satisfies the following conditional expression (1).
2 <ft / fw (1)
Here, fw is the focal length at the wide-angle end, and ft is the focal length at the telephoto end.

Moreover, the following conditional expression (2) is satisfied.
4 <d1 / fw (2)
Here, d1 is the amount of change in the distance between the first lens group and the second lens group.

Furthermore, the following conditional expression (3) is satisfied.
7 <d1 / fw (3)
Here, d1 is a change amount of the interval between the first lens group and the second lens group.

Moreover, the following conditional expression (4) is satisfied.
d2 / fw <-3 (4)
Here, d2 is the amount of change in the distance between the second lens group and the third lens group.

Furthermore, the following conditional expression (5) is satisfied.
d2 / fw <−5 (5)
Here, d2 is a change amount of the interval between the second lens group and the third lens group.

  Furthermore, the imaging apparatus includes the zoom optical system and an imaging element having an imaging surface that converts an optical image into an electrical signal.

  According to the present invention, it is possible to provide a zoom optical system having a large half field angle at the wide-angle end and a large zoom ratio to the telephoto end.

FIG. 3 is a cross-sectional view taken along the optical axis of the zoom lens according to the first exemplary embodiment. FIG. 6 is a cross-sectional view taken along the optical axis by developing the zoom lens of Example 2. FIG. 6 is a cross-sectional view taken along the optical axis by developing the zoom lens of Example 3. FIG. 6 is an aberration diagram of the zoom lens according to Example 1; FIG. 6 is an aberration diagram of the zoom lens according to Example 2; FIG. 6 is an aberration diagram of the zoom lens according to Example 3; It is sectional drawing of the imaging device which used the zoom lens of this embodiment as an interchangeable lens. It is a front perspective view which shows the external appearance of the digital camera of this embodiment. It is a back perspective view showing the appearance of the digital camera of this embodiment. It is a block diagram which shows the control structure of the digital camera of this embodiment.

  The zoom optical system of the present invention will be described below based on examples.

  FIG. 1 is a diagram illustrating a first example of the zoom optical system according to the embodiment.

The zoom optical system according to this embodiment includes, in order from the object side to the image side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a positive refractive power. G3, and zooming is performed by moving at least the first lens group G1 and the second lens group G2, and the distance between the first lens group G1 and the second lens group G2 at the telephoto end is smaller than at the wide-angle end. In addition, the first lens group G1 is convex on the object side in order from the object side to the image side so that the distance between the second lens group G2 and the third lens group G3 at the telephoto end becomes larger than at the wide angle end. And a negative meniscus lens L11 and a negative lens L12 having a half angle of view of 90 ° or more at the wide angle end and satisfying the following conditional expression (1).
2 <ft / fw (1)
However,
fw is the focal length at the wide-angle end,
ft is the focal length at the telephoto end,
It is.

  Conditional expression (1) defines a predetermined zoom ratio. If the lower limit of conditional expression (1) is not reached, the zoom ratio from the wide-angle end to the telephoto end will be small, and it will be difficult to capture a realistic image.

Moreover, it is preferable that the following conditional expression (2) is satisfied.
4 <d1 / fw (2)
Here, d1 is the amount of change in the distance between the first lens group G1 and the second lens group G2.

  Conditional expression (2) is the amount of change in the group interval between the strong negative first lens group G1 and the positive second lens group G2. If the lower limit of conditional expression (2) is not reached, the negative refractive power of the first lens group G1 becomes too strong and the aberration around the image increases, and at the same time, the spherical aberration generated in the second lens group G2 increases. It becomes impossible to correct with other lens groups.

Furthermore, it is preferable that the following conditional expression (3) is satisfied.
7 <d1 / fw (3)
Here, d1 is the amount of change in the distance between the first lens group and the second lens group.

  In particular, when the zoom ratio is 5 times or more, it is preferable to satisfy the conditional expression (3). If the lower limit of conditional expression (3) is not reached, the negative refractive power of the first lens group G1 becomes strong, and aberrations around the image appear at the same time, and spherical aberration generated in the second lens group G2 appears. It becomes difficult to correct with the lens group.

Moreover, it is preferable that the following conditional expression (4) is satisfied.
d2 / fw <-3 (4)
Here, d2 is the amount of change in the distance between the second lens group and the third lens group.

  Conditional expression (4) is a condition that defines the amount of change in the group interval between the second lens group G2 and the third lens group G3, and changes in the direction away from the wide-angle end to the telephoto end. If the upper limit of conditional expression (4) is exceeded, the refractive power of the second lens group G2 becomes too strong, and the spherical aberration occurring in the second lens group G2 cannot be corrected.

Furthermore, it is preferable that the following conditional expression (5) is satisfied.
d2 / fw <−5 (5)
Here, d2 is a change amount of the interval between the second lens group and the third lens group.

  In particular, when the zoom ratio is 5 times or more, it is preferable to satisfy the conditional expression (5). When the upper limit of conditional expression (5) is exceeded, the refractive power of the second lens group G2 becomes strong, and it becomes difficult to correct spherical aberration that occurs in the second lens group G2.

  Each embodiment shown below is a zoom lens that can be used for moving image shooting, as an interchangeable lens mounted on a camera body without a quick return mirror.

  The zoom optical system according to the first to third embodiments of the present invention will be described with reference to the drawings. 1 to 3 are sectional views taken along the optical axis of the zoom optical system according to the first to third embodiments of the present invention. In each figure, (a) shows the wide-angle end (WE), (b) shows the intermediate state (ST), and (c) shows the telephoto end (TE).

  FIG. 1 is a sectional view of the zoom optical system according to the first embodiment.

  As shown in the drawing, the zoom optical system of Example 1 includes, in order from the object side to the image side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a positive refractive power. G3. In the figure, S indicates an aperture stop, I indicates an image plane, and C indicates a cover glass.

  The first lens group G1 includes, in order from the object side to the image side, a negative meniscus lens L11 having a convex surface directed toward the object side, a negative meniscus lens L12 having a convex surface directed toward the object side, a biconcave negative lens L13, and a biconvex positive lens It consists of a cemented lens SU11 of the lens L14 and a biconcave negative lens L15.

  The second lens group G2 includes, in order from the object side to the image side, a biconvex positive lens L21, a cemented lens SU21 of a biconvex positive lens L22 and a biconcave negative lens L23, a biconcave negative lens L24, and a biconvex positive lens L25. The cemented lens SU22 and a biconvex positive lens L26. An aperture stop S is disposed between the object side cemented lens SU21 and the image side cemented lens SU22 of the second lens group G2.

  The third lens group G3 includes, in order from the object side to the image side, a biconcave negative lens L31, a biconvex positive lens L32, and a biconvex positive lens L33.

  The operation of the zoom optical system of Embodiment 1 will be described. In the zoom operation, the first lens group G1, the second lens group G2, and the third lens group G3 move independently. The aperture stop S moves together with the second lens group G2.

  When zooming from the wide-angle end to the telephoto end, each lens unit moves as follows.

  The first lens group G1 moves to the image side while narrowing the distance from the second lens group G2 from the wide-angle end to the intermediate state, and moves from the intermediate state to the telephoto end while reducing the distance from the second lens group G2 to the object side. Move to.

  The second lens group G2 moves toward the object side from the wide-angle end to the telephoto end while narrowing the distance from the first lens group G1 and widening the distance from the third lens group G3.

  The third lens group G3 moves to the image side while increasing the distance from the second lens group G2 from the wide-angle end to the intermediate state, and moves from the intermediate state to the telephoto end while increasing the distance from the second lens group G2 to the object side. Move to.

  FIG. 2 is a sectional view of the zoom optical system according to the second embodiment.

  As shown in the drawing, the zoom optical system according to Example 2 includes, in order from the object side to the image side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a positive refractive power. G3. In the figure, S indicates an aperture stop, I indicates an image plane, and C indicates a cover glass.

  The first lens group G1 includes, in order from the object side to the image side, a negative meniscus lens L11 having a convex surface directed toward the object side, a biconcave negative lens L12, a biconcave negative lens L13, and a positive meniscus having a convex surface directed toward the object side. And a cemented lens SU11 of the lens L14.

  The second lens group G2 includes, in order from the object side to the image side, a biconvex positive lens L21, a cemented lens SU21 of a biconvex positive lens L22 and a biconcave negative lens L23, a biconcave negative lens L24, and a biconvex positive lens L25. The cemented lens SU22 and a biconvex positive lens L26. An aperture stop S is disposed between the object side cemented lens SU21 and the image side cemented lens SU22 of the second lens group G2.

  The third lens group G3 includes, in order from the object side to the image side, a cemented lens SU31 of a biconcave negative lens L31 and a biconvex positive lens L32, a negative meniscus lens L33 having a convex surface directed toward the object side, and a biconvex positive lens L34. And a biconvex positive lens L34.

  The operation of the zoom optical system of Embodiment 2 will be described. In the zoom operation, the first lens group G1, the second lens group G2, and the third lens group G3 move independently. The aperture stop S moves together with the second lens group G2.

  When zooming from the wide-angle end to the telephoto end, each lens unit moves as follows.

  The first lens group G1 moves to the image side while narrowing the distance from the second lens group G2 from the wide-angle end to the intermediate state, and moves from the intermediate state to the telephoto end while reducing the distance from the second lens group G2 to the object side. Move to.

  The second lens group G2 moves toward the object side from the wide-angle end to the telephoto end while narrowing the distance from the first lens group G1 and widening the distance from the third lens group G3.

  The third lens group G3 moves to the image side while increasing the distance from the second lens group G2 from the wide-angle end to the intermediate state, and moves from the intermediate state to the telephoto end while increasing the distance from the second lens group G2 to the object side. Move to.

  As shown in the drawing, the zoom optical system according to the third embodiment includes, in order from the object side to the image side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a positive refractive power. G3. In the figure, S indicates an aperture stop, I indicates an image plane, and C indicates a cover glass.

  The first lens group G1 includes, in order from the object side to the image side, a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, a biconcave negative lens L13, and the object side. And a cemented lens SU11 of a positive meniscus lens L14 having a convex surface.

  The second lens group G2 includes, in order from the object side to the image side, a biconvex positive lens L21, a cemented lens SU21 of a biconvex positive lens L22 and a biconcave negative lens L23, and a negative meniscus lens L24 having a convex surface directed toward the object side. And a cemented lens SU22 of a biconvex positive lens L25, and a planoconvex positive lens L26 having a convex surface facing the object side. An aperture stop S is disposed between the object side cemented lens SU21 and the image side cemented lens SU22 of the second lens group G2.

  The third lens group G3 includes, in order from the object side to the image side, a negative meniscus lens L31 having a convex surface directed to the image side, a negative meniscus lens L32 having a convex surface directed to the image side, a biconvex positive lens L33, and an object side And a negative meniscus lens L34 having a convex surface facing the object side, a positive meniscus lens L35 having a convex surface facing the object side, and a positive meniscus lens L36 having a convex surface facing the object side.

  The operation of the zoom optical system of Embodiment 3 will be described. In the zoom operation, the third lens group G3 is fixed, and the first lens group G1 and the second lens group G2 move independently. The aperture stop S moves together with the second lens group G2.

  When zooming from the wide-angle end to the telephoto end, each lens unit moves as follows.

  The first lens group G1 moves to the image side while narrowing the distance from the second lens group G2 from the wide-angle end to the intermediate state, and moves from the intermediate state to the telephoto end while reducing the distance from the second lens group G2 to the object side. Move to.

  The second lens group G2 moves toward the object side from the wide-angle end to the telephoto end while narrowing the distance from the first lens group G1 and widening the distance from the third lens group G3.

  Various numerical data (surface data, zoom data, group focal length) of the first to third embodiments are shown below.

  The surface data includes, for each surface number, the radius of curvature r of each lens surface (optical surface), the surface interval d, the refractive index nd of each lens (optical medium) with respect to the d-line (587.6 nm), and each lens (optical medium). The Abbe number νd of the d line is shown. The unit of the radius of curvature r and the surface interval d is millimeters (mm). In the surface data, “∞” described in the radius of curvature indicates infinite.

The zoom data shows various zoom data at the wide-angle end (WE), intermediate (ST), and telephoto end (TE). As the zoom data, a focal length, an F number (Fno), an angle of view (2ω), an image height, a back focus (BF), a total length, and a variable surface interval d are shown. In the group small dot distance, focal lengths f1 to f3 in the first to third lens groups are shown.

Numerical example 1
Surface data surface number r d nd νd
Object plane ∞ ∞
1 74.68 3.00 1.8499 43.0
2 18.67 14.37
3 68.49 3.00 1.8498 43.0
4 31.81 6.92
5 -61.81 3.00 1.4875 70.4
6 21.07 11.00 1.7505 32.9
7 -213.53 0.21
8 -153.55 2.00 1.6943 49.4
9 58.88 d9 (variable)
10 46.05 3.00 1.7440 44.8
11 -53.62 0.20
12 19.91 3.84 1.6201 36.3
13 -24.21 1.50 1.7527 28.1
14 22.90 0.76
15 (Aperture) ∞ 9.99
16 -398.08 2.00 1.7522 30.6
17 22.39 5.50 1.4876 70.4
18 -39.43 2.65
19 32.63 5.00 1.7381 42.3
20 -181.22 d20 (variable)
21 -30.03 1.50 1.7460 28.0
22 32.75 1.40
23 74.88 5.50 1.6204 60.3
24 -37.14 0.20
25 34.14 4.50 1.6644 53.0
26 -134.27 d26 (variable)
27 ∞ 0.42 1.5168 64.2
28 ∞ 2.00
Image plane ∞

Zoom data
WE ST TE
f 7.629 11.091 19.848
Fno 2.933 3.260 4.000
ω 92.529 61.686 30.843
Statue height 12.029
fb (in air) 6.796 6.761 9.838
Total length (in air) 140.000 129.063 130.022

d9 35.486 17.875 0.1
d20 6.262 12.971 28.628
d26 6.796 6.761 9.838

Group focal length f1 -13.377
f2 28.900
f3 137.284

Numerical example 2
Surface data surface number r d nd νd
Object plane ∞ ∞
1 76.45 3.00 1.8499 43.0
2 19.11 18.54
3 -459.26 3.00 1.8498 43.0
4 75.59 4.29
5 -77.90 2.50 1.4875 70.4
6 22.51 7.23 1.7551 27.6
7 61.32 d7 (variable)
8 66.99 3.50 1.6829 34.0
9 -54.43 0.20
10 26.83 5.85 1.5931 39.5
11 -26.37 1.50 1.7530 29.8
12 35.65 1.43
13 (Aperture) ∞ 6.55
14 -590.33 2.00 1.7552 27.6
15 28.53 7.00 1.4875 70.4
16 -34.54 6.47
17 43.55 5.00 1.6139 43.4
18 -145.82 d18 (variable)
19 -70.32 2.00 1.7440 44.8
20 19.85 4.97 1.6567 54.1
21 -125.10 0.23
22 65.95 2.00 1.7523 30.6
23 25.76 8.96
24 72.09 5.50 1.4875 70.4
25 -71.79 0.20
26 40.08 5.50 1.4875 70.4
27 -211.23 d27 (variable)
28 ∞ 0.42 1.5168 64.2
29 ∞ 2.00
Image plane ∞

Zoom data
WE ST TE
f 7.7487 16.238 35.162
Fno 2.174 2.768 4.000
ω 92.529 41.124 18.506
Statue height 12.029
fb (in air) 9.812 9.204 11.299
Total length (in air) 169.768 144.765 159.398

d7 61.935 20.746 0.090
d18 0.421 16.607 51.900
d27 9.812 9.204 11.299

Group focal length f1 -14.517
f2 33.976
f3 100.860

Numerical Example 3
Surface data surface number r d nd νd
Object plane ∞ ∞
1 128.83 3.00 1.8499 43.0
2 32.21 12.96
3 419.13 3.00 1.8498 43.0
4 103.40 9.85
5 -45.39 1.00 1.4875 70.4
6 29.30 7.12 1.7552 27.6
7 54.89 d7 (variable)
8 42.44 7.21 1.5563 45.7
9 -100.84 0.10
10 38.12 11.02 1.4875 70.4
11 -34.90 1.00 1.7440 44.8
12 48.79 3.33
13 (Aperture) ∞ 0.32
14 164.54 1.00 1.7539 28.8
15 34.34 11.72 1.4875 70.4
16 -42.81 0.10
17 51.32 6.29 1.6534 35.1
18 ∞ d18 (variable)
19 -22.91 1.00 1.7475 37.4
20 -41.61 0.10
21 -267.94 12.51 1.4875 70.4
22 -33.15 0.10
23 50.82 7.42 1.4875 70.4
24 -79.31 0.10
25 27.56 1.00 1.7552 27.6
26 14.94 4.38
27 35.20 11.01 1.5335 65.9
28 131.93 0.10
29 18.78 4.23 1.4875 70.4
30 30.69 2.65
31 ∞ 0.42 1.5168 64.2
32 ∞ 3.00
Image plane ∞

Zoom data
WE ST TE
f 8.2159 12.4308 73.8851
Fno 2.737 1.746 4.070
ω 92.529 50.120 7.711
Statue height 12.029
fb (in air) 2.645 2.645 2.645
Total length (in air) 190.931 176.776 296.935

d7 64.970 39.972 0.100
d18 5.000 15.842 175.873

Group focal length f1 -18.837
f2 25.188
f3 53.339

  4 to 6 are graphs showing various aberrations at infinite object points at (a) wide angle end (WE), (b) intermediate (ST), and (c) telephoto end (TE) in Examples 1 to 3. FIG. is there.

  In these various aberration diagrams, SA represents spherical aberration, AS represents astigmatism, and DT represents distortion. The spherical aberration SA is shown for each wavelength of 587.6 nm (d line: broken line), 435.8 nm (g line: alternate long and short dash line), and 656.3 nm (C line: solid line). In the astigmatism AS, a solid line indicates a sagittal image plane and a broken line indicates a meridional image plane. FNO indicates the F number, and FIY indicates the maximum image height.

About the said Examples 1-3, the value of each conditional expression (1)-(3) is shown below.

Example 1 Example 2 Example 3
Conditional expression (1) 2.602 4.538 8.993
Conditional expression (2) 4.638 7.981 7.896
Conditional expression (3) -2.932 -6.643 -20.798

  FIG. 7 is a cross-sectional view of a single-lens mirrorless camera as an image pickup apparatus using the zoom lens of this embodiment and using a small CCD or CMOS as an image pickup device. In FIG. 7, reference numeral 1 denotes a single lens mirrorless camera, 2 denotes an imaging lens system disposed in the lens barrel, 3 denotes a lens barrel mounting portion that allows the imaging lens system 2 to be attached to and detached from the single lens mirrorless camera 1, and a screw A mount of type or bayonet type is used. In this example, a bayonet type mount is used. Reference numeral 4 denotes an image sensor surface, and 5 denotes a back monitor.

 As the imaging lens system 2 of the single-lens mirrorless camera 1 having such a configuration, for example, the zoom lens of the present embodiment shown in Examples 1 to 7 is used.

  8 and 9 are conceptual diagrams of the configuration of the imaging apparatus according to the present embodiment in which a zoom lens is incorporated in the photographing optical system 41. FIG. FIG. 8 is a front perspective view showing the appearance of a digital camera 40 as an image pickup apparatus, and FIG. 9 is a rear perspective view of the same.

  The digital camera 40 of this embodiment includes a photographing optical system 41 positioned on the photographing optical path 42, a shutter button 45, a liquid crystal display monitor 47, and the like. When the shutter button 45 disposed on the top of the digital camera 40 is pressed, In conjunction with this, photographing is performed through the photographing optical system 41, for example, the zoom lens of the first embodiment. An object image formed by the photographing optical system 41 is formed on an image sensor (photoelectric conversion surface) provided in the vicinity of the imaging surface. The object image received by the image sensor is displayed on the liquid crystal display monitor 47 provided on the back of the camera as an electronic image by the processing means. In addition, the photographed electronic image can be recorded in a recording unit.

  FIG. 10 is a block diagram showing an internal circuit of a main part of the digital camera 40 of the present embodiment. In the following description, the processing unit 51 described above is configured by, for example, the CDS / ADC unit 24, the temporary storage memory 17, the image processing unit 18, and the like, and the storage unit 52 is configured by a storage medium unit or the like.

  As shown in FIG. 10, the digital camera 40 is connected to the operation unit 12, the control unit 13 connected to the operation unit 12, and the control signal output port of the control unit 13 via buses 14 and 15. The imaging drive circuit 16, the temporary storage memory 17, the image processing unit 18, the storage medium unit 19, the display unit 20, and the setting information storage memory unit 21 are provided.

  The temporary storage memory 17, the image processing unit 18, the storage medium unit 19, the display unit 20, and the setting information storage memory unit 21 can mutually input and output data via the bus 22. In addition, a CCD 49 and a CDS / ADC unit 24 are connected to the imaging drive circuit 16.

  The operation unit 12 includes various input buttons and switches, and notifies the control unit of event information input from the outside (camera user) via these buttons. The control unit 13 is a central processing unit composed of, for example, a CPU, and has a built-in program memory (not shown) and controls the entire digital camera 40 according to a program stored in the program memory.

  The CCD 49 is an image pickup device that is driven and controlled by the image pickup drive circuit 16, converts the light amount of each pixel of the object image formed via the image pickup optical system 41 into an electric signal, and outputs the electric signal to the CDS / ADC unit 24.

The CDS / ADC unit 24 amplifies the electric signal input from the CCD 49, performs analog / digital conversion, and performs raw video data (Bayer data, hereinafter referred to as RAW data) obtained by performing the amplification and digital conversion. ) To the temporary memory 17.
The temporary storage memory 17 is a buffer made of, for example, SDRAM, and is a memory device that temporarily stores RAW data output from the CDS / ADC unit 24. The image processing unit 18 reads out the RAW data stored in the temporary storage memory 17 or the RAW data stored in the storage medium unit 19, and includes distortion correction based on the image quality parameter designated by the control unit 13. It is a circuit that performs various image processing electrically.

  The storage medium unit 19 is detachably mounted with a card-type or stick-type storage medium made of, for example, a flash memory, and the RAW data transferred from the temporary storage memory 17 and the image processing unit 18 to these flash memories. Image-processed image data is recorded and held.

  The display unit 20 includes a liquid crystal display monitor 47 and the like, and displays captured RAW data, image data, an operation menu, and the like. The setting information storage memory unit 21 includes a ROM unit that stores various image quality parameters in advance, and a RAM unit that stores image quality parameters read from the ROM unit by an input operation of the operation unit 12.

  By adopting the zoom lens of the present invention as the imaging optical system 41, the digital camera 40 configured in this way can be a small imaging device suitable for moving image imaging.

  Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and embodiments configured by appropriately combining the configurations of the respective embodiments also fall within the scope of the present invention. Is.

DESCRIPTION OF SYMBOLS 1 ... Lens interchangeable camera 2 ... Imaging lens system 3 ... Mount part 4 ... Image pick-up element surface 5 ... Back monitor 12 ... Operation part 13 ... Control part 14, 15 ... Bus 16 ... Imaging drive circuit 17 ... Temporary memory 18 ... Image Processing unit 19 ... Storage medium unit 20 ... Display unit 21 ... Setting information storage memory unit 22 ... Bus 24 ... CDS / ADC unit 40 ... Digital camera 41 ... Shooting optical system 42 ... Shooting optical path 45 ... Shutter button 47 ... Liquid crystal display monitor

Claims (6)

From the object side to the image side,
A first lens unit G1 having negative refractive power;
A second lens group G2 having a positive refractive power;
A third lens group G3 having a positive refractive power;
With
Zooming is performed by moving at least the first lens group and the second lens group,
The distance between the first lens group and the second lens group at the telephoto end is smaller than that at the wide-angle end, and
The distance between the second lens unit and the third lens unit at the telephoto end is larger than that at the wide-angle end.
The first lens group includes, in order from the object side to the image side, a negative meniscus lens having a convex surface directed toward the object side, and a negative lens, and has a half field angle of 90 ° or more at the wide angle end,
A zoom optical system satisfying the following conditional expression (1):
2 <ft / fw (1)
However,
fw is the focal length at the wide-angle end,
ft is the focal length at the telephoto end,
It is. The zoom optical system according to claim 1, wherein the following conditional expression (2) is satisfied.
4 <d1 / fw (2)
Here, d1 is the amount of change in the distance between the first lens group and the second lens group. The zoom optical system according to claim 1, wherein the following conditional expression (3) is satisfied.
7 <d1 / fw (3)
Here, d1 is a change amount of the interval between the first lens group and the second lens group. The zoom optical system according to claim 1, wherein the following conditional expression (4) is satisfied.
d2 / fw <-3 (4)
Here, d2 is the amount of change in the distance between the second lens group and the third lens group. The zoom optical system according to claim 1, wherein the following conditional expression (5) is satisfied.
d2 / fw <−5 (5)
Here, d2 is a change amount of the interval between the second lens group and the third lens group. The zoom optical system according to any one of claims 1 to 5,
An imaging device having an imaging surface for converting an optical image into an electrical signal;
An imaging apparatus comprising:

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