WO2012173023A1 - Zoom lens and image pickup device - Google Patents

Abstract

Provided are a compact zoom lens able to achieve both increased compactness and a higher variable power and also satisfactorily correct aberrations, and an image pickup device using this lens. The zoom lens has a function able to form an object image on the imaging plane of a solid-state imaging element, and includes in order from the object side a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power. Zooming is performed by changing the intervals between lens groups, the fourth lens group includes in order from the object side a positive lens and a negative lens, an air interval is formed between the positive lens and the negative lens, and the fourth lens group satisfies a predetermined conditional expression.

Description

Zoom lens and imaging apparatus

The present invention relates to a zoom lens that includes a plurality of lens groups and performs zooming by changing the distance between the lens groups in the optical axis direction, and an imaging apparatus including the zoom lens.

In recent years, digital still cameras and video cameras using solid-state image sensors such as CCD (Charged Coupled Device) type image sensors or CMOS (Complementary Metal Oxide Semiconductor) type image sensors have become more compact and highly variable. There is an increasing demand for zoom lenses that achieve both magnifications.

As a zoom lens with a high zoom ratio, in general, a zoom lens having a four-group configuration (referred to as a positive / negative / positive / positive type) including a positive lens group, a negative lens group, a positive lens group, and a positive lens group in order from the object side is well known. For example, Patent Documents 1 and 2 disclose this type of four-group zoom lens.

On the other hand, as a zoom lens that achieves a high zoom ratio and optical performance by increasing the number of movable lenses compared to a positive, negative, positive, positive four-group zoom lens, the positive lens group, negative lens group, positive lens A zoom lens having a five-group configuration (referred to as a positive, negative, positive, and positive type) including a lens group, a negative lens group, and a positive lens group is known. For example, Patent Document 3 discloses a zoom lens having a five-group configuration of this type. Yes.

JP 2008-146016 A JP 2011-28238 JP JP 2009-282398

However, the zoom lens described in Patent Document 1 has a zoom ratio as small as 6 to 7, and a higher zoom ratio is desired. On the other hand, the zoom lens described in Patent Document 2 has a relatively large zoom ratio of 9 to 12 times. However, since the total length at the telephoto end is large, further compactness is desired. From these facts, it can be said that it is difficult to achieve both compactness and high zoom ratio in a positive / negative / positive type four-group zoom lens.

In the zoom lens described in Patent Document 3, although the zoom ratio is as high as 9 to 20 times, the total length at the telephoto end is also large, and the fourth lens group is a single lens. Since the lens or cemented lens is used and the ability to correct off-axis aberrations such as coma and curvature of field is not so large, it is difficult to further reduce the total length at the telephoto end while maintaining optical performance. It can be said that there is.

The present invention has been made in view of such problems, and a zoom lens in which various aberrations are favorably corrected while achieving both compactness and high zoom ratio, and an imaging apparatus using the same The purpose is to provide.

The zoom lens according to claim 1, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power; In a zoom lens that includes a fourth lens group having a negative refractive power and a fifth lens group having a positive refractive power, and performs zooming by changing the interval between the lens groups,
The fourth lens group includes, in order from the object side, a positive lens and a negative lens. The positive lens and the negative lens are spaced apart from each other, and satisfy the following conditional expression.
−0.30 <f4 / fT <−0.05 (1)
0.1 <Pair4 / P4 <1.5 (2)
However,
Pair 4: The refractive power P4 of the so-called air lens formed by the positive lens image side surface of the fourth lens group and the negative lens object side surface of the fourth lens group: the refractive power f4 of the fourth lens group: the first lens Focal length fT of the four lens groups: focal length of the entire system at the telephoto end Pair 4 is given by the following [Equation 1].

ただし、
　ｎ₄₁：前記第４レンズ群の正レンズのｄ線に対する屈折率
　ｎ₄₂：前記第４レンズ群の負レンズのｄ線に対する屈折率
　Ｒ₄₂：前記第４レンズ群の正レンズの像側面の曲率半径
　Ｒ₄₃：前記第４レンズ群の負レンズの物体側面の曲率半径
　Ｄ₄：前記第４レンズ群の正レンズと、前記第４レンズ群の負レンズの軸上の空気間隔　

However,
n ₄₁ : refractive index with respect to d-line of positive lens of the fourth lens group n ₄₂ : refractive index with respect to d-line of negative lens of the fourth lens group R ₄₂ : curvature of image side surface of positive lens of the fourth lens group Radius R ₄₃ : Radius of curvature of the object side surface of the negative lens of the fourth lens group D ₄ : Air spacing on the axis of the positive lens of the fourth lens group and the negative lens of the fourth lens group

The basic configuration of the present invention for obtaining a zoom lens having both a small size and a high zoom ratio, in which aberrations are well corrected, is a first lens group having a positive refractive power and a negative refractive power in order from the object side. A second lens group having positive refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power, and a fifth lens group having positive refractive power. With this configuration, there are two negative lens groups, so the refractive power configuration in the entire lens system becomes symmetrical, and various aberrations corrected by symmetrical shapes such as distortion, coma, and lateral chromatic aberration are corrected. It becomes possible to correct effectively.

Conditional expression (1) defines the ratio between the focal length of the fourth lens group and the focal length at the telephoto end. When the value of conditional expression (1) is less than the upper limit value, the fourth lens group has an appropriate negative refractive power. Therefore, compared to the conventional positive / negative / positive / positive type configuration, the fourth lens group causes a negative jump. Therefore, off-axis rays that pass through the first to third lens units on the object side further pass near the optical axis, thereby enabling downsizing. On the other hand, when the value of conditional expression (1) exceeds the lower limit value, it is possible to suppress the occurrence of off-axis aberrations due to excessive refractive power of the fourth lens group. Moreover, it is desirable to satisfy the following conditional expressions.
−0.20 <f4 / fT <−0.05 (1) ′

Conditional expression (2) defines the ratio between the refractive power of the air lens formed by the positive lens and the negative lens of the fourth lens group and the refractive power of the fourth lens group. When using two lenses in the fourth lens group in a positive / negative / positive / positive type lens configuration as in the present invention, a positive / negative or negative / positive cemented lens may be formed in consideration of the effects of manufacturing errors. However, in the thin and small zoom lenses that are required in recent years, the fourth lens group also has a large burden in correcting aberrations, and single lenses and cemented lenses have the ability to correct off-axis aberrations such as coma and field curvature. Is not so high that aberrations that cannot be corrected remain. Therefore, by making the value of conditional expression (2) exceed the lower limit value, the curvature of field and coma aberration can be corrected more effectively than using a cemented lens by the action of an air lens having negative refractive power. Can be done. On the other hand, by setting the value of conditional expression (2) below the upper limit, off-axis aberrations caused by the curvature of each lens of the fourth lens group forming the air lens can be suppressed.

According to a second aspect of the present invention, in the zoom lens according to the first aspect, the third lens group includes, in order from the object side, a positive 3p1 lens, a negative 3n lens, and a positive 3p2 lens. It satisfies the following conditional expression.
0.15 <n3n-n3p2 <0.50 (3)
30 <ν3p2-ν3n <60 (4)
However,
n3n: refractive index of the 3n lens n3p2: refractive index of the 3p2 lens ν3p2: Abbe number of the 3p2 lens ν3n: Abbe number of the 3n lens

According to the present invention, the third lens group includes, in order from the object side, a positive 3p1 lens, a negative 3n lens, and a positive 3p2 lens. By disposing the 3p1 lens having the positive refractive power closest to the object side, the light diverged by the negative power of the second lens group can be efficiently converged and the spherical aberration can be effectively corrected.

In addition, when a brighter zoom lens is demanded as the number of pixels of a solid-state image sensor increases, a spherical aberration generated by reducing the F-number is further reduced with a 3n lens having negative refractive power, positive refraction By arranging a 3p2 lens that has power, it is possible to effectively correct spherical aberration generated by reducing the F-number by combining a negative lens and a positive lens, and also to effectively correct chromatic aberration and coma aberration. I can do it.

Conditional expression (3) defines the difference in refractive index between the 3n lens and the 3p2 lens. When the value of conditional expression (3) exceeds the lower limit, a combination of a negative lens with a high refractive index and a positive lens with a low refractive index is combined, effectively correcting spherical aberration and coma that could not be corrected by the 3p1 lens. I can do it. On the other hand, when the value of conditional expression (3) is below the upper limit value, it can be made of a glass material that is easily available. It is more desirable to satisfy the following conditional expression.
0.20 <n3n-n3p2 <0.45 (3) ′

Further, conditional expression (4) defines the difference in Abbe number between the 3p2 lens and the 3n lens. When the value of conditional expression (4) exceeds the lower limit value, a combination of a negative lens having a large dispersion and a positive lens having a small dispersion can be obtained, and chromatic aberration can be effectively corrected. On the other hand, when the value of conditional expression (4) is below the upper limit value, it can be made of a glass material that is easily available. Moreover, it is desirable to satisfy the following conditional expressions.
40 <ν3p2-ν3n <55 (4) ′

In addition, it is desirable to join the 3n lens and the 3p2 lens because the 3n lens and the 3p2 lens have a large luminous flux passing through the lens and are easily affected by the optical performance due to the manufacturing error of the lens.

According to a third aspect of the present invention, in the zoom lens according to the first or second aspect, the second lens group includes, in order from the object side, a negative lens having a concave surface facing the image side and a concave surface facing the image side. And a positive lens having a convex surface facing the object side.

The second lens group includes, in order from the object side, a negative lens having a concave surface facing the image side, a negative lens having a concave surface facing the image side, and a positive lens having a convex surface facing the object side. By arranging two negative lenses with a concave surface facing the image side on the object side, light rays incident at a large angle from the first lens group having a large diameter are quickly relaxed, and field curvature and distortion are effectively corrected. I can do it. Further, by arranging a positive lens having a convex surface on the object side on the image side, it is possible to effectively correct lateral chromatic aberration at the wide-angle end and axial chromatic aberration at the telephoto end. In addition, since the air space between the negative lens and the positive lens is often extremely narrow, and is susceptible to the optical performance due to the manufacturing error of the lens, it is desirable to join them.

A zoom lens according to a fourth aspect of the invention is characterized in that, in the invention according to any one of the first to third aspects, the following conditional expression is satisfied.
_{0.2 <n 42 - n 41 <} 0.4 (5)

Conditional expression (5) defines the difference in refractive index between the positive lens and the negative lens in the fourth lens group. When the value of conditional expression (5) exceeds the lower limit, in the fourth lens group having negative refractive power, a combination of a low refractive index positive lens and a high refractive index negative lens results in an increase in Petzval sum. The curvature of field can be corrected by holding down. On the other hand, when the value of conditional expression (5) is below the upper limit value, it can be made of an easily obtainable glass material. Moreover, it is desirable to satisfy the following conditional expressions.
_{0.2 <n 42 - n 41 <} 0.3 (5) '

A zoom lens according to claim 5 is characterized in that, in the invention according to any one of claims 1 to 4, the following conditional expression is satisfied.
1.50 <f1 / (fW × fT) ^1/2 <2.50 (6)
−0.20 <f2 / (fW × fT) ^1/2 <−0.40 (7)
However,
f1: focal length of the first lens group f2: focal length of the second lens group fW: focal length of the entire system at the wide-angle end fT: focal length of the entire system at the telephoto end

Conditional expression (6) and conditional expression (7) respectively define the focal lengths of the first lens group and the second lens group and the ratio of the focal length intermediate between the wide-angle end and the telephoto end. When the value of conditional expression (6) falls below the upper limit value and the value of conditional expression (7) exceeds the lower limit value, the first lens group having a positive refractive power having a large role during zooming and the negative refractive power The refractive power of the second lens group having the above becomes stronger, so that both high zooming and thinning can be achieved. On the other hand, when the value of conditional expression (6) exceeds the lower limit value and the value of conditional expression (7) falls below the upper limit value, off-axis aberration is generated due to excessive refractive power of the first lens group and the second lens group. Can be suppressed.

A zoom lens according to a sixth aspect of the present invention is the zoom lens according to any one of the first to fifth aspects, wherein the first lens group includes, in order from the object side, a single negative lens and a single positive lens. It has a lens, The cemented surface of the cemented lens is convex on the object side, and satisfies the following conditional expression.
0.3 <n1N-n1P <0.6 (8)
However,
n1N: refractive index with respect to d-line of the negative lens in the cemented lens of the first lens group n1P: refractive index with respect to d-line of the positive lens in the cemented lens of the first lens group

The first lens group has a cemented lens composed of one negative lens and one positive lens in order from the object side. Further, conditional expression (8) defines the difference in refractive index between the negative lens and the positive lens of the cemented lens. When the cemented surface is convex on the object side and the value of conditional expression (8) exceeds the lower limit, the cemented surface becomes a divergent surface having negative refractive power, and the spherical aberration at the telephoto end is effectively corrected. I can do it. On the other hand, when the value of conditional expression (8) is less than the upper limit value, it can be made of an easily obtainable glass material.

In addition, by arranging a positive lens on the image side of the cemented lens, it is possible to share the refractive power due to the positive refractive surface of the cemented lens, so coma aberration due to excessive refractive power due to the positive refractive surface of the cemented lens, etc. Can be suppressed. Therefore, it is desirable to arrange a positive lens on the image side of the cemented lens.

A zoom lens according to a seventh aspect is characterized in that, in the invention according to any one of the first to sixth aspects, the following conditional expression is satisfied.
1.5 <(D1 + D2) / fW <3.0 (9)
However,
D1: Thickness on the optical axis of the first lens group D2: Thickness on the optical axis of the second lens group fW: Focal length of the entire system at the wide angle end

Conditional expression (9) defines the ratio of the sum of the thickness on the optical axis of the first lens group and the second lens group and the focal length at the wide angle end. In zoom lenses that are required to be smaller and thinner, each lens group is housed when not in use, and is generally thinner than when shooting. The air space between the lens groups can be reduced by storage, but the thickness of the lens group on the optical axis cannot be reduced by storage. Therefore, by setting the value of conditional expression (9) below the upper limit value, the thickness of the first lens group and the second lens group on the optical axis is reduced, and compactness during storage is possible. On the other hand, by making the value of conditional expression (9) exceed the lower limit value, it is possible to prevent the first lens group and the second lens group from being excessively thinned, and to secure the edge thickness necessary for the lens performance. Become.

A zoom lens according to an eighth aspect of the present invention is the zoom lens according to any one of the first to seventh aspects, wherein the fifth lens group does not move in the optical axis direction during zooming or focusing. .

The fifth lens group is the lens group closest to the solid-state image sensor. If the fifth lens group is moved during zooming or focusing, the distance from the solid-state image sensor will be reduced, and the final lens will be affected by dust and scratches. There is also a risk of receiving it. On the other hand, since the distance between the final lens and the solid-state imaging device is fixed by not moving the fifth lens group, it is possible to suppress the influence of dust and scratches. In addition, since the solid-state image sensor is in a sealed state, dust such as dust can be prevented from entering the solid-state image sensor.

A zoom lens according to a ninth aspect is the invention according to any one of the first to eighth aspects, wherein the fifth lens group is a single lens.

Since the fifth lens group is close to the image plane, the light beam passing through the lens is thin, and the amount of spherical aberration and coma generated is relatively small. Therefore, it is desirable to configure the fifth lens group with a single lens in order to achieve cost reduction and downsizing of the optical system.

The zoom lens according to claim 10 is characterized in that, in the invention according to any one of claims 1 to 9, the zoom lens performs focusing by moving the fourth lens group.

By focusing with the fourth lens group, it is possible to obtain a clear image up to a short distance object without causing an increase in the total optical length or an increase in the front lens diameter due to the extension.

A zoom lens according to an eleventh aspect is the invention according to any one of the first to tenth aspects, further comprising a lens having substantially no power. That is, even when a dummy lens having substantially no power is added to the configuration of claim 1, it is within the scope of application of the present invention.

An imaging apparatus according to an eleventh aspect includes the zoom lens according to any one of the first to tenth aspects.

According to the present invention, it is possible to provide a zoom lens in which various aberrations are favorably corrected and an image pickup apparatus using the same while achieving both compactness and high zoom ratio.

It is the perspective view (a) seen from the front upper side of the digital camera carrying the imaging device concerning this Embodiment, and the perspective view (b) seen from the back lower side. It is a block diagram of the imaging device which has the zoom lens concerning this Embodiment. 3 is a cross-sectional view of the zoom lens of Example 1. FIG. FIG. 4 is aberration diagrams (spherical aberration, astigmatism, distortion) of the zoom lens of Example 1, where (a) is an aberration diagram at the wide-angle end, (b) is an intermediate lens, and (c) is an aberration diagram at the telephoto end. 6 is a cross-sectional view of a zoom lens according to Example 2. FIG. FIG. 4A is an aberration diagram (spherical aberration, astigmatism, distortion) of the zoom lens of Example 2, wherein (a) is an aberration diagram at the wide-angle end, (b) is an intermediate lens, and (c) is an aberration diagram at the telephoto end. 6 is a cross-sectional view of a zoom lens of Example 3. FIG. FIG. 4A is an aberration diagram (spherical aberration, astigmatism, distortion) of the zoom lens of Example 3, (a) is an aberration diagram at the wide angle end, (b) is an intermediate lens, and (c) is an aberration diagram at the telephoto end. 6 is a cross-sectional view of a zoom lens according to Example 4. FIG. FIG. 7A is an aberration diagram of the zoom lens according to the fourth exemplary embodiment (spherical aberration, astigmatism, distortion), (a) is an aberration diagram at the wide-angle end, (b) is an intermediate lens, and (c) is an aberration diagram at the telephoto end. 6 is a cross-sectional view of a zoom lens according to Example 5. FIG. FIG. 6A is an aberration diagram (spherical aberration, astigmatism, distortion) of the zoom lens of Example 5; (a) is an aberration diagram at the wide angle end, (b) is an intermediate lens, and (c) is an aberration diagram at the telephoto end. 10 is a cross-sectional view of a zoom lens according to Example 6. FIG. FIG. 10A is an aberration diagram of the zoom lens according to the sixth exemplary embodiment (spherical aberration, astigmatism, distortion), (a) is an aberration diagram at the wide-angle end, (b) is an intermediate lens, and (c) is an aberration diagram at the telephoto end. 10 is a cross-sectional view of a zoom lens according to Example 7. FIG. FIG. 10A is an aberration diagram of the zoom lens according to the seventh exemplary embodiment (spherical aberration, astigmatism, distortion), (a) is an aberration diagram at the wide angle end, (b) is an intermediate lens, and (c) is an aberration diagram at the telephoto end.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1A and 1B are a perspective view as viewed from the front upper side and a perspective view as viewed from the lower back side of the digital camera equipped with the image pickup apparatus according to the present embodiment. FIG. It is a block diagram of an imaging device having a zoom lens according to the embodiment.

1A, a digital camera DC includes a retractable lens barrel 80 that includes a zoom lens 101 and retracts with respect to a camera body 81, a finder window 82, a release button 83, and a flash light emitting unit 84. , A strap attaching portion 87, a USB terminal 88, and a lens cover 89. When the lens cover 89 is opened, a switch (not shown) is turned on, and the lens barrel 80 is moved forward to enter a shooting state. On the other hand, when the lens cover 89 is closed after shooting is finished, the switch (not shown) is turned off. The lens barrel 80 is retracted. Since the configuration for retracting the lens barrel 80 is well known, the following details are not described.

Further, in FIG. 1B, the digital camera DC includes a finder eyepiece 91 and red and green display lamps that display AF and AE information to the photographer by light emission or blinking when the release button 83 is pressed. 92, a zoom button 93 for zooming up and down according to the operation of the photographer, a menu / set button 95 for various settings, a four-way switch 96 as a selection button, an image, other character information, and the like. A monitor LCD 112 to be displayed, a playback button 97 for playing back an image shot on the monitor LCD 112, a display button 98 for selecting display or deletion of an image displayed on the monitor LCD 112 or other character information, and a shot and recorded image Erasing button 99, tripod hole 71, and battery / card cover 72 that can be freely opened and closed. The photographer can display various menus on the monitor LCD 112 with the menu / set button 95, select with the selection button 96, and confirm the setting with the menu / set button 95. Inside the battery / card cover 72, a battery for supplying power to the digital camera DC and a card-type removable memory for recording captured images are loaded.

Furthermore, as shown in FIG. 2, the imaging apparatus 100 mounted on the digital camera DC includes a zoom lens 101, a solid-state imaging device 102 that is an APS format, an A / D conversion unit 103, a control unit 104, and an optical unit. System drive unit 105, timing generation unit 106, image sensor drive unit 107, image memory 108, image processing unit 109, image compression unit 110, image recording unit 111, monitor LCD 112, and FIG. The operation unit 113 including the above-described button group is configured.

The zoom lens 101 has a function of forming a subject image on the imaging surface of the solid-state imaging device 102. The zoom lens according to the present embodiment includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power; In a zoom lens that includes a fourth lens group having a negative refractive power and a fifth lens group having a positive refractive power, and performs zooming by changing the interval between the lens groups, the fourth lens group includes: The lens is composed of a positive lens and a negative lens in order from the object side. The positive lens and the negative lens are spaced apart from each other, and satisfy the following conditional expression.
−0.30 <f4 / fT <−0.05 (1)
0.1 <Pair4 / P4 <1.5 (2)
However,
Pair 4: Refracting power of a so-called air lens formed by the positive lens image side surface of the fourth lens group and the negative lens object side surface of the fourth lens group P4: refracting power of the fourth lens group f4: of the fourth lens group Focal length fT: Focal length of the entire system at the telephoto end Pair 4 is expressed by the following [Equation 1].

ただし、
　ｎ₄₁：第４レンズ群の正レンズのｄ線に対する屈折率
　ｎ₄₂：第４レンズ群の負レンズのｄ線に対する屈折率
　Ｒ₄₂：第４レンズ群の正レンズの像側面の曲率半径
　Ｒ₄₃：第４レンズ群の負レンズの物体側面の曲率半径
　Ｄ₄：第４レンズ群の正レンズと、前記第４レンズ群の負レンズの軸上の空気間隔

However,
n ₄₁ : refractive index with respect to d-line of positive lens of fourth lens group n ₄₂ : refractive index with respect to d-line of negative lens of fourth lens group R ₄₂ : radius of curvature of image side surface of positive lens of fourth lens group R ₄₃ : Curvature radius of object side surface of negative lens of fourth lens group D ₄ : Air spacing on axis of positive lens of fourth lens group and negative lens of fourth lens group

The solid-state image sensor 102 is an image sensor such as a CCD or CMOS, and includes an RGB color filter. The solid-state image sensor 102 photoelectrically converts incident light for each of R, G, and B and outputs an analog signal thereof. The A / D conversion unit 103 converts an analog signal into digital image data.

The control unit 104 controls each unit of the imaging apparatus 100. The control unit 104 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory), and various programs read out from the ROM and expanded in the RAM, and various types in cooperation with the CPU. Execute the process.

The optical system driving unit 105 controls driving of the zoom lens 101 in zooming, focusing, exposure, and the like under the control of the control unit 104. The timing generator 106 outputs a timing signal for analog signal output. The image sensor drive unit 107 performs scanning drive control of the solid-state image sensor 102.

The image memory 108 stores image data so as to be readable and writable. The image processing unit 109 performs various image processes on the image data. The image compression unit 110 compresses the captured image data using a compression method such as JPEG (Joint Photographic Experts Group). The image recording unit 111 records image data on a recording medium such as a memory card set in a slot (not shown).

The monitor LCD 112 is a color liquid crystal panel or the like, and displays image data after shooting, a through image before shooting, various operation screens, and the like. The operation unit 113 outputs information input by the user to the control unit 104 via the button group described above with reference to FIG.

Here, the operation of the imaging apparatus 100 will be described. In subject photographing, subject monitoring (through image display) and image photographing execution are performed. In monitoring, an image of the subject obtained through the zoom lens 101 is formed on the light receiving surface (imaging surface) of the solid-state image sensor 102. A solid-state imaging device 102 disposed behind the photographing optical axis of the zoom lens 101 is scanned and driven by a timing generation unit 106 and an imaging device driving unit 107, and serves as a photoelectric conversion output corresponding to an optical image formed at regular intervals. Output analog signal for one screen.

The analog signal is appropriately gain-adjusted for each primary color component of RGB, and then converted into digital data by the A / D conversion unit 103. The digital data is subjected to color process processing including pixel interpolation processing and γ correction processing by the image processing unit 109 to generate a luminance signal Y and color difference signals Cb, Cr (image data) as digital values, and the image memory. 108, the signal is periodically read out and the video signal is generated and output to the monitor LCD 112. Note that the control unit 104, which is a white balance adjusting unit, adjusts the white balance so that the signal intensity of the blue wavelength component in the image signal is smaller than the signal intensity of the other colors.

The monitor LCD 112 functions as an electronic viewfinder in monitoring and displays captured images in real time. In this state, zooming, focusing, exposure, and the like of the zoom lens 101 are performed by driving the optical system driving unit 105 based on an input through the operation unit 113 performed according to the operation of the release button 83 of the photographer. Is set.

In such a monitoring state, when the user operates the release button 83 at a timing at which still image shooting is desired, still image data is shot. In response to the operation of the release button 83, one frame of image data stored in the image memory 108 is read out and compressed by the image compression unit 110. The compressed image data is recorded in the removable memory by the image recording unit 111.

In addition, by turning off a power switch (not shown), the zoom lens 101 moves so that the mutual group interval becomes narrow, and performs a collapsing operation. At this time, it is preferable that the third lens group and the fifth lens group (or the fourth lens group) are retracted from the optical path because the entire length after retracting is shortened.

Note that the descriptions in the above embodiment and each example are examples of a suitable zoom lens and imaging apparatus according to the present invention, and the present invention is not limited thereto. The imaging apparatus can also be installed in a video camera.

(Example)
Next, examples suitable for the above-described embodiment will be described. However, the present invention is not limited to the following examples.
f: Focal length of the entire zoom lens system Fno: F number 2Y: Diagonal length of the imaging surface of the solid-state imaging device R: Radius of curvature D: Spacing on the axial surface Nd: Refractive index of lens material with respect to d-line νd: Abbe number of lens material

In each embodiment, the surface described with “*” after each surface number is a surface having an aspheric shape, and the shape of the aspheric surface has the vertex of the surface as the origin and the X axis in the optical axis direction. The height in the direction perpendicular to the optical axis is h and is expressed by the following “Equation 2”.

ただし、
Ａｉ：ｉ次の非球面係数
Ｒ　：曲率半径
Ｋ　：円錐定数

However,
Ai: i-order aspheric coefficient R: radius of curvature K: conic constant

Example 1
Table 1 shows lens data of Example 1. In the following (including the lens data in the table), a power of 10 (for example, 2.5 × 10 ⁻⁰² ) is expressed using E (for example, 2.5E-02). FIG. 3 is a cross-sectional view of the zoom lens according to the first exemplary embodiment at the wide angle end. In the drawing, Gr1 is a positive first lens group, and is composed of a negative first lens L1, a positive second lens L2 (L1 and L2 are cemented and the cemented surface is convex on the object side), and a third lens L3. Gr2 is a negative second lens group, a negative fourth lens L4 having a concave surface facing the image side, a negative fifth lens L5 having a concave surface facing the image side, and a positive lens having a convex surface facing the object side. The sixth lens L6 (L5 and L6 are cemented), Gr3 is a positive third lens group, and is a seventh lens (positive 3p1 lens) L7 and an eighth lens (negative 3n lens). ) L8, a ninth lens (positive 3p2 lens) L9 (L8, L9 are cemented), Gr4 is a negative fourth lens group, a positive tenth lens L10, a negative eleventh lens Consists of a lens L11, Gr5 is a positive fifth lens group, and is composed of a twelfth lens L12. , S is an aperture stop, I is showing an imaging plane. F1 and F2 are parallel flat plates assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state image sensor, and the like.

[Table 1]
Example 1

f = 4.46-16.75-63.61
Fno = 3.7-5.2-5.5
Zoom ratio = 14.25

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 38.749 0.90 2.00070 25.5 10.38
2 23.068 3.75 1.49700 81.6 10.08
3 -192.187 0.12 10.00
4 19.233 2.83 1.72920 54.7 9.70
5 56.392 d1 9.41
6 * 47.642 0.50 1.88200 37.2 4.32
7 * 5.186 2.41 3.33
8 -7.461 0.50 1.72920 54.7 3.01
9 11.705 1.25 1.94590 18.0 2.95
10 -44.804 d2 2.90
11 (Aperture) ∞ d3 1.86
12 * 4.592 1.39 1.55330 71.7 2.19
13 * -23.478 0.65 2.15
14 17.796 0.50 1.88300 40.8 2.06
15 3.528 2.41 1.49710 81.6 1.96
16 * -7.018 d4 2.00
17 -11.355 1.06 1.59270 35.5 2.19
18 -4.430 0.79 2.26
19 * -2.548 0.50 1.85 130 40.1 2.12
20 * -8.970 d5 2.38
21 * 32.555 2.66 1.61880 63.9 3.95
22 * -7.688 1.00 4.19
23 ∞ 0.30 1.51680 64.2 4.10
24 ∞ 0.50 4.09
25 ∞ 0.50 1.51680 64.2 4.06
26 ∞ 0.50 4.05

Aspheric coefficient

6th surface 19th surface K = 0.00000E + 00 K = 0.00000E + 00
A4 = -0.20794E-02 A4 = 0.13723E-01
A6 = 0.18305E-03 A6 = 0.15383E-02
A8 = -0.62827E-05 A8 = -0.28605E-03
A10 = 0.78352E-07 A10 = -0.15988E-04
A12 = 0.90523E-05

Surface 7 Surface 20 K = 0.00000E + 00 K = 0.00000E + 00
A4 = -0.24564E-02 A4 = 0.48200E-02
A6 = 0.89980E-04 A6 = 0.15189E-02
A8 = 0.98852E-05 A8 = -0.50982E-03
A10 = -0.38988E-06 A10 = 0.56169E-04
A12 = -0.21953E-05

Surface 12 Surface 21 K = 0.00000E + 00 K = 0.00000E + 00
A4 = -0.82139E-03 A4 = -0.24712E-03
A6 = -0.21836E-03 A6 = -0.20341E-03
A8 = 0.10212E-03 A8 = 0.17620E-04
A10 = -0.23399E-04 A10 = -0.52041E-06
A12 = 0.17517E-05 A12 = 0.64744E-08

Surface 13 Surface 22 K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.93910E-03 A4 = 0.53120E-02
A6 = -0.22937E-04 A6 = -0.80634E-03
A8 = 0.38098E-04 A8 = 0.52452E-04
A10 = -0.13873E-04 A10 = -0.16847E-05
A12 = 0.12349E-05 A12 = 0.24029E-07

16th face K = 0.00000E + 00
A4 = -0.20827E-04
A6 = -0.17706E-03
A8 = 0.63702E-04
A10 = -0.12513E-04
A12 = 0.89882E-06

Focal length at each position (wide angle, intermediate, telephoto), F number, between groups

F Fno angle of view 2Y d1 d2 d3 d4 d5
4.47 3.70 82.4 6.642 0.50 11.06 0.50 2.99 1.00
16.75 5.20 26.3 8.103 9.82 3.51 1.01 5.69 3.26
63.61 5.50 7.0 8.077 19.80 0.70 0.66 4.01 5.23

Lens group data

Lens group Start surface Focal length (mm)
1 1 31.15
2 6 -4.49
3 12 7.09
4 17 -7.20
5 21 10.31

FIG. 4 is an aberration diagram of Example 1 (spherical aberration, astigmatism, distortion). Here, FIG. 4A is an aberration diagram at the wide-angle end. FIG. 4B is an aberration diagram in the middle. FIG. 4C is an aberration diagram at the telephoto end. Here, in the spherical aberration diagram, g represents the amount of spherical aberration with respect to the g line and d represents the amount of spherical aberration with respect to the d line. In the astigmatism diagram, the solid line S represents the sagittal plane, and the dotted line M represents the meridional plane (the same applies hereinafter).

In the zoom lens of Example 1, when zooming from the wide angle end to the telephoto end, the first lens group Gr1, the second lens group Gr2, the aperture stop S, the third lens group Gr3, and the fourth lens group Gr4 are in the optical axis direction. Can be changed by changing the distance between each lens group. The fifth lens group Gr5 is fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the fourth lens L4, the seventh lens L7, the ninth lens L9, the eleventh lens L11, and the twelfth lens L12 are glass mold lenses, and the other lenses are polished lenses made of a glass material.

(Example 2)
Table 2 shows lens data of Example 2. FIG. 5 is a cross-sectional view at the wide-angle end of the zoom lens according to the second exemplary embodiment. In the drawing, Gr1 is a positive first lens group, and is composed of a negative first lens L1, a positive second lens L2 (L1 and L2 are cemented and the cemented surface is convex on the object side), and a third lens L3. Gr2 is a negative second lens group, a negative fourth lens L4 having a concave surface facing the image side, a negative fifth lens L5 having a concave surface facing the image side, and a positive lens having a convex surface facing the object side. The sixth lens L6 (L5 and L6 are cemented), Gr3 is a positive third lens group, and is a seventh lens (positive 3p1 lens) L7 and an eighth lens (negative 3n lens). ) L8, a ninth lens (positive 3p2 lens) L9 (L8, L9 are cemented), Gr4 is a negative fourth lens group, a positive tenth lens L10, a negative eleventh lens Consists of a lens L11, Gr5 is a positive fifth lens group, and is composed of a twelfth lens L12. , S is an aperture stop, I is showing an imaging plane. F1 and F2 are parallel flat plates assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state image sensor, and the like.

[Table 2]
Example 2

f = 6.2-16.75-63.61
Fno = 4.0-5.1-5.5
Zoom ratio = 10.26

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 36.486 0.70 2.00070 25.5 10.59
2 22.573 3.85 1.49700 81.6 10.18
3 -214.687 0.12 10.00
4 18.360 2.69 1.72920 54.7 9.66
5 43.652 d1 9.36
6 * 182.928 0.50 1.77250 49.6 3.91
7 5.811 2.44 3.17
8 -6.150 0.50 1.88300 40.8 2.78
9 30.834 1.20 1.94590 18.0 2.82
10 -13.730 d2 3.10
11 (Aperture) ∞ d3 1.75
12 * 4.064 1.37 1.62260 58.2 2.13
13 * -106.308 0.33 2.06
14 19.712 0.50 1.88300 40.8 2.01
15 2.960 2.76 1.49710 81.6 1.89
16 * -6.253 d4 2.00
17 -12.070 1.03 1.59270 35.5 2.20
18 -4.717 1.07 2.27
19 * -2.507 0.50 1.88200 37.2 2.14
20 * -8.537 d5 2.45
21 * -130 24.303 2.50 1.80 140 45.5 4.07
22 * -6.718 1.00 4.27
23 ∞ 0.30 1.51680 64.2 4.09
24 ∞ 0.50 4.07
25 ∞ 0.50 1.51680 64.2 4.03
26 ∞ 0.30 4.01

Aspheric coefficient

6th surface 19th surface K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.22472E-03 A4 = 0.98592E-02
A6 = 0.92212E-06 A6 = 0.17369E-02
A8 = -0.21856E-06 A8 = -0.13721E-03
A10 = 0.10070E-07 A10 = -0.28247E-04
A12 = 0.90538E-05

Surface 12 Surface 20 K = 0.00000E + 00 K = 0.00000E + 00
A4 = -0.93187E-03 A4 = 0.19692E-02
A6 = -0.12020E-03 A6 = 0.14338E-02
A8 = 0.42022E-04 A8 = -0.40705E-03
A10 = -0.17834E-04 A10 = 0.47233E-04
A12 = 0.17510E-05 A12 = -0.21963E-05

Surface 13 Surface 21 K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.92958E-03 A4 = -0.99304E-03
A6 = 0.53352E-04 A6 = 0.14587E-04
A8 = -0.39360E-04 A8 = 0.15118E-05
A10 = -0.54305E-05 A10 = 0.14160E-08
A12 = 0.12353E-05 A12 = -0.31027E-09

16th 22nd K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.41208E-04 A4 = 0.20372E-02
A6 = -0.21390E-03 A6 = -0.23088E-03
A8 = 0.85192E-04 A8 = 0.16034E-04
A10 = -0.16187E-04 A10 = -0.52641E-06
A12 = 0.90049E-06 A12 = 0.84343E-08

Focal length at each position (wide angle, intermediate, telephoto), F number, between groups

F Fno angle of view 2Y d1 d2 d3 d4 d5
6.20 4.00 64.4 7.367 1.59 7.36 0.99 3.45 1.41
16.75 5.10 26.3 8.015 10.44 3.29 1.29 4.52 3.65
63.61 5.50 7.0 7.962 20.36 0.22 0.80 2.62 5.95

Lens group data

Lens group Start surface Focal length (mm)
1 1 32.00
2 6 -4.89
3 12 7.04
4 17 -6.78
5 21 8.39

FIG. 6 is an aberration diagram of Example 2 (spherical aberration, astigmatism, distortion). Here, FIG. 6A is an aberration diagram at the wide-angle end. FIG. 6B is an aberration diagram in the middle. FIG. 6C is an aberration diagram at the telephoto end.

In the zoom lens of Example 2, when zooming from the wide-angle end to the telephoto end, the first lens group Gr1, the second lens group Gr2, the aperture stop S, the third lens group Gr3, and the fourth lens group Gr4 are in the optical axis direction. Can be changed by changing the distance between each lens group. The fifth lens group Gr5 is fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the fourth lens L4, the seventh lens L7, the ninth lens L9, the eleventh lens L11, and the twelfth lens L12 are glass mold lenses, and the other lenses are polished lenses made of a glass material.

(Example 3)
Table 3 shows lens data of Example 3. FIG. 7 is a cross-sectional view at the wide-angle end of the zoom lens according to the third exemplary embodiment. In the drawing, Gr1 is a positive first lens group, and is composed of a negative first lens L1, a positive second lens L2 (L1 and L2 are cemented and the cemented surface is convex on the object side), and a third lens L3. Gr2 is a negative second lens group, a negative fourth lens L4 having a concave surface facing the image side, a negative fifth lens L5 having a concave surface facing the image side, and a positive lens having a convex surface facing the object side. The sixth lens L6 (L5 and L6 are cemented), Gr3 is a positive third lens group, and is a seventh lens (positive 3p1 lens) L7 and an eighth lens (negative 3n lens). ) L8, a ninth lens (positive 3p2 lens) L9 (L8, L9 are cemented), Gr4 is a negative fourth lens group, a positive tenth lens L10, a negative eleventh lens Consists of a lens L11, Gr5 is a positive fifth lens group, and is composed of a twelfth lens L12. , S is an aperture stop, I is showing an imaging plane. F1 and F2 are parallel flat plates assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state image sensor, and the like.

[Table 3]
Example 3

f = 4.47-16.75-63.6
Fno = 3.7-5.1-5.5
Zoom ratio = 14.24

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 36.296 0.70 2.00070 25.5 10.36
2 22.089 3.63 1.49700 81.6 10.07
3 -301.240 0.12 10.00
4 18.668 2.86 1.72920 54.7 9.69
5 52.150 d1 9.38
6 * 48.009 0.50 1.77250 49.6 4.73
7 5.890 2.49 3.57
8 -6.541 0.50 1.88300 40.8 3.15
9 15.577 1.28 1.94590 18.0 3.12
10 -20.356 d2 3.10
11 (Aperture) ∞ d3 1.83
12 * 4.081 1.13 1.69350 53.2 2.22
13 * 17.369 0.23 2.09
14 14.689 0.50 1.91080 35.3 2.07
15 3.618 3.08 1.49710 81.6 1.96
16 * -6.324 d4 2.00
17 -16.170 1.06 1.59270 35.5 2.12
18 -4.910 0.96 2.17
19 * -2.515 0.50 1.85130 40.1 2.02
20 * -11.744 d5 2.26
21 * 25.082 2.77 1.53050 55.7 4.27
22 * -5.213 1.00 4.38
23 ∞ 0.30 1.51680 64.2 4.17
24 ∞ 0.50 4.15
25 ∞ 0.50 1.51680 64.2 4.11
26 ∞ 0.30 4.08

Aspheric coefficient

6th surface 19th surface K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.10994E-03 A4 = 0.16951E-01
A6 = 0.30694E-05 A6 = -0.39899E-03
A8 = -0.29828E-06 A8 = 0.15055E-03
A10 = 0.10957E-07 A10 = -0.38582E-04
A12 = 0.83937E-05

Surface 12 Surface 20 K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.60360E-03 A4 = 0.81166E-02
A6 = 0.11224E-03 A6 = -0.41875E-03
A8 = 0.28659E-04 A8 = -0.10620E-03
A10 = -0.84768E-05 A10 = 0.20099E-04
A12 = 0.14956E-05 A12 = -0.10919E-05

Surface 13 Surface 21 K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.28736E-02 A4 = -0.12094E-02
A6 = 0.25317E-03 A6 = 0.98659E-04
A8 = 0.16859E-04 A8 = -0.55443E-05
A10 = -0.11694E-04 A10 = 0.20532E-06
A12 = 0.27366E-05 A12 = -0.19720E-08

16th 22nd K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.60417E-03 A4 = 0.35216E-02
A6 = 0.54828E-04 A6 = -0.27674E-03
A8 = -0.93917E-05 A8 = 0.21535E-04
A10 = 0.48482E-05 A10 = -0.85591E-06
A12 = -0.31607E-06 A12 = 0.16839E-07

Focal length at each position (wide angle, intermediate, telephoto), F number, between groups

F Fno angle of view 2Y d1 d2 d3 d4 d5
4.47 3.70 82.4 6.642 0.30 12.01 0.00 2.51 1.01
16.75 5.10 26.3 8.157 9.52 3.73 1.15 4.53 3.88
63.60 5.50 7.0 8.107 19.03 0.00 1.18 3.34 6.13

Lens group data

Lens group Start surface Focal length (mm)
1 1 31.11
2 6 -4.76
3 12 6.98
4 17 -6.30
5 21 8.40

FIG. 8 is an aberration diagram of Example 3 (spherical aberration, astigmatism, distortion). Here, FIG. 8A is an aberration diagram at the wide-angle end. FIG. 8B is an aberration diagram in the middle. FIG. 8C is an aberration diagram at the telephoto end.

In the zoom lens of Example 3, the first lens group Gr1, the second lens group Gr2, the aperture stop S, the third lens group Gr3, and the fourth lens group Gr4 are arranged in the optical axis direction during zooming from the wide-angle end to the telephoto end. Can be changed by changing the distance between each lens group. The fifth lens group Gr5 is fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the fourth lens L4, the seventh lens L7, the ninth lens L9, and the eleventh lens L11 are glass mold lenses, the twelfth lens L12 is a plastic lens, and the other lenses are polished lenses made of a glass material.

Example 4
Table 4 shows lens data of Example 4. FIG. 9 is a cross-sectional view at the wide-angle end of the zoom lens according to the fourth exemplary embodiment. In the drawing, Gr1 is a positive first lens group, and is composed of a negative first lens L1, a positive second lens L2 (L1 and L2 are cemented and the cemented surface is convex on the object side), and a third lens L3. Gr2 is a negative second lens group, a negative fourth lens L4 having a concave surface facing the image side, a negative fifth lens L5 having a concave surface facing the image side, and a positive lens having a convex surface facing the object side. Gr3 is a positive third lens group, and includes a seventh lens (positive 3p1 lens) L7, an eighth lens (negative 3n lens) L8, and a ninth lens (positive 3p2). Lens) L9 (L8 and L9 are cemented), Gr4 is a negative fourth lens group, which is composed of a positive tenth lens L10 and a negative eleventh lens L11, and Gr5 is positive The fifth lens group is composed of a twelfth lens L12, S is an aperture stop, and I is an imaging surface. . F1 and F2 are parallel flat plates assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state image sensor, and the like.

[Table 4]
Example 4

f = 4.46-16.83-45.69
Fno = 3.7-5.1-6.08
Zoom ratio = 10.24

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 30.557 0.70 2.00070 25.5 10.46
2 19.535 3.79 1.49700 81.6 9.78
3 661.736 0.12 9.53
4 17.327 3.06 1.72920 54.7 8.82
5 47.230 d1 8.37
6 * 36.672 0.50 1.88300 40.8 4.63
7 6.821 2.08 3.67
8 -9.069 0.50 1.88300 40.8 3.35
9 7.432 0.30 3.13
10 8.678 1.39 1.94590 18.0 3.17
11 -626.938 d2 3.10
12 (Aperture) ∞ d3 1.85
13 * 4.010 1.29 1.72900 54.0 2.31
14 * 11.432 0.28 2.16
15 15.223 0.50 1.91080 35.3 2.14
16 3.876 1.91 1.49710 81.6 2.01
17 * -6.005 d4 2.00
18 42.463 1.09 1.63980 34.6 2.06
19 -6.756 0.57 2.06
20 * -3.258 0.50 1.85130 40.1 1.96
21 * 67.964 d5 2.06
22 * 111.311 2.87 1.49710 81.6 4.40
23 * -5.201 1.58 4.44
24 ∞ 0.30 1.51680 64.2 4.10
25 ∞ 0.50 4.07
26 ∞ 0.50 1.51680 64.2 4.02
27 ∞ 1.05 3.98

Aspheric coefficient

6th surface 20th surface K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.10283E-04 A4 = 0.17498E-01
A6 = 0.25137E-05 A6 = -0.25709E-02
A8 = -0.90226E-07 A8 = 0.30881E-03
A10 = 0.39120E-08 A10 = -0.13594E-04
A12 = -0.41775E-08

Surface 13 Surface 21 K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.51940E-03 A4 = 0.12609E-01
A6 = 0.13454E-04 A6 = -0.22292E-02
A8 = -0.17092E-04 A8 = 0.22894E-03
A10 = 0.20255E-05 A10 = -0.10931E-04
A12 = -0.30908E-06 A12 = 0.10329E-07

Surface 14 Surface 22 K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.30825E-02 A4 = 0.21680E-03
A6 = 0.50419E-05 A6 = 0.33643E-04
A8 = -0.27576E-04 A8 = -0.11423E-05
A10 = -0.28873E-05 A10 = 0.51484E-07
A12 = 0.20701E-07 A12 = -0.78113E-10

17th 23rd K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.77727E-03 A4 = 0.23096E-02
A6 = 0.26352E-03 A6 = -0.87254E-04
A8 = -0.34749E-04 A8 = 0.91883E-05
A10 = 0.14507E-04 A10 = -0.40487E-06
A12 = -0.32749E-06 A12 = 0.10259E-07

Focal length at each position (wide angle, intermediate, telephoto), F number, between groups

F Fno angle of view 2Y d1 d2 d3 d4 d5
4.46 3.70 82.4 6.633 0.33 12.25 0.00 2.07 1.00
16.83 5.10 26.1 7.913 9.12 4.21 1.33 3.78 4.79
45.69 6.08 9.8 7.717 14.66 0.50 1.79 4.86 7.43

Lens group data

Lens group Start surface Focal length (mm)
1 1 29.72
2 6 -4.54
3 13 6.77
4 18 -6.86
5 22 10.08

FIG. 10 is an aberration diagram of Example 4 (spherical aberration, astigmatism, distortion). Here, FIG. 10A is an aberration diagram at the wide-angle end. FIG. 10B is an aberration diagram in the middle. FIG. 10C is an aberration diagram at the telephoto end.

In the zoom lens of Example 4, the first lens group Gr1, the second lens group Gr2, the aperture stop S, the third lens group Gr3, and the fourth lens group Gr4 are arranged in the optical axis direction upon zooming from the wide-angle end to the telephoto end. Can be changed by changing the distance between each lens group. The fifth lens group Gr5 is fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the fourth lens L4, the seventh lens L7, the ninth lens L9, the eleventh lens L11, and the twelfth lens L12 are glass mold lenses, and the other lenses are polished lenses made of a glass material.

(Example 5)
Table 5 shows lens data of Example 5. FIG. 11 is a cross-sectional view at the wide-angle end of the zoom lens according to the fifth embodiment. In the drawing, Gr1 is a positive first lens group, and is composed of a negative first lens L1, a positive second lens L2 (L1 and L2 are cemented and the cemented surface is convex on the object side), and a third lens L3. Gr2 is a negative second lens group, a negative fourth lens L4 having a concave surface facing the image side, a negative fifth lens L5 having a concave surface facing the image side, and a positive lens having a convex surface facing the object side. Gr3 is a positive third lens group, and includes a seventh lens (positive 3p1 lens) L7, an eighth lens (negative 3n lens) L8, and a ninth lens (positive 3p2). Lens) L9 (L8 and L9 are cemented), Gr4 is a negative fourth lens group, which is composed of a positive tenth lens L10 and a negative eleventh lens L11, and Gr5 is positive The fifth lens group is composed of a twelfth lens L12, S is an aperture stop, and I is an imaging surface. . F1 and F2 are parallel flat plates assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state image sensor, and the like.

[Table 5]
Example 5

f = 4.34-16.27-61.86
Fno = 3.7-5.1-5.5
Zoom ratio = 14.25

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 40.914 0.70 1.90200 25.1 10.96
2 22.109 3.67 1.49700 81.6 10.07
3 -223.464 0.12 10.00
4 18.995 2.75 1.77250 49.6 9.72
5 50.282 d1 9.43
6 41.046 0.50 1.88300 40.8 4.78
7 5.191 2.33 3.57
8 * -16.224 0.50 1.85130 40.1 3.34
9 * 8.612 0.20 3.19
10 7.672 1.70 1.94590 18.0 3.25
11 51.298 d2 3.10
12 (Aperture) ∞ d3 1.65
13 * 5.200 1.21 1.80 140 45.5 2.06
14 * -48.265 0.22 2.04
15 -23.431 0.50 1.80610 33.3 2.00
16 4.500 1.95 1.49710 81.6 1.95
17 * -5.156 d4 2.00
18 16.852 1.24 1.59270 35.5 2.20
19 -6.316 0.39 2.18
20 * -7.272 0.50 1.85130 40.1 2.07
21 * 5.380 d5 2.15
22 * 44.975 2.50 1.49710 81.6 4.22
23 * -10.336 1.00 4.13
24 ∞ 0.30 1.51680 64.2 3.98
25 ∞ 0.50 3.96
26 ∞ 0.50 1.51680 64.2 3.95
27 ∞ 0.95 3.99

Aspheric coefficient

Surface 8 Surface 20 K = 0.00000E + 00 K = 0.00000E + 00
A4 = -0.26324E-02 A4 = -0.78448E-02
A6 = 0.16164E-03 A6 = 0.13756E-02
A8 = 0.61898E-06 A8 = -0.16895E-03
A10 = -0.28852E-06 A10 = 0.79765E-05
A12 = -0.41775E-08

Surface 9 Surface 21 K = 0.00000E + 00 K = 0.00000E + 00
A4 = -0.21608E-02 A4 = -0.78719E-02
A6 = 0.19453E-03 A6 = 0.14708E-02
A8 = 0.15386E-05 A8 = -0.18594E-03
A10 = -0.38846E-06 A10 = 0.97015E-05
A12 = 0.10329E-07

Surface 13 Surface 22 K = 0.00000E + 00 K = 0.00000E + 00
A4 = -0.58987E-03 A4 = 0.13668E-02
A6 = -0.75182E-04 A6 = 0.11470E-03
A8 = -0.20223E-04 A8 = -0.89183E-05
A10 = -0.50262E-05 A10 = 0.30217E-06
A12 = -0.30908E-06 A12 = -0.30985E-08

14th 23rd K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.18263E-03 A4 = 0.11363E-02
A6 = 0.46907E-04 A6 = 0.63828E-05
A8 = -0.96349E-04 A8 = 0.44685E-05
A10 = 0.53110E-06 A10 = -0.41337E-06
A12 = 0.20701E-07 A12 = 0.11047E-07

17th page
K = 0.00000E + 00
A4 = 0.19647E-02
A6 = -0.93669E-04
A8 = 0.52370E-04
A10 = -0.34576E-06
A12 = -0.32749E-06

Focal length at each position (wide angle, intermediate, telephoto), F number, between groups

F Fno angle of view 2Y d1 d2 d3 d4 d5
4.34 3.70 86.1 6.838 0.37 10.05 1.08 2.08 1.01
16.27 5.10 28.0 8.172 9.83 2.29 1.30 4.08 3.19
61.86 5.50 7.5 7.543 20.26 0.13 1.50 0.88 7.65

Lens group data

Lens group Start surface Focal length (mm)
1 1 31.25
2 6 -4.88
4 13 6.59
5 18 -7.88
6 22 17.17

FIG. 12 is an aberration diagram of Example 5 (spherical aberration, astigmatism, distortion). Here, FIG. 12A is an aberration diagram at the wide-angle end. FIG. 12B is an aberration diagram in the middle. FIG. 12C is an aberration diagram at the telephoto end.

In the zoom lens of Example 5, when zooming from the wide angle end to the telephoto end, the first lens group Gr1, the second lens group Gr2, the aperture stop S, the third lens group Gr3, and the fourth lens group Gr4 are in the optical axis direction. Can be changed by changing the distance between each lens group. The fifth lens group Gr5 is fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the fifth lens L5, the seventh lens L7, the ninth lens L9, the eleventh lens L11, and the twelfth lens L12 are glass mold lenses, and the other lenses are polished lenses made of a glass material.

(Example 6)
Table 6 shows lens data of Example 6. FIG. 13 is a cross-sectional view of the zoom lens of Example 6 at the wide-angle end. In the drawing, Gr1 is a positive first lens group, and is composed of a negative first lens L1, a positive second lens L2 (L1 and L2 are cemented and the cemented surface is convex on the object side), and a third lens L3. Gr2 is a negative second lens group, a negative fourth lens L4 having a concave surface facing the image side, a negative fifth lens L5 having a concave surface facing the image side, and a positive lens having a convex surface facing the object side. Gr3 is a positive third lens group, and includes a seventh lens (positive 3p1 lens) L7, an eighth lens (negative 3n lens) L8, and a ninth lens (positive 3p2). Lens) L9 (L8 and L9 are cemented), Gr4 is a negative fourth lens group, which is composed of a positive tenth lens L10 and a negative eleventh lens L11, and Gr5 is positive The fifth lens group is composed of a twelfth lens L12, S is an aperture stop, and I is an imaging surface. . F1 and F2 are parallel flat plates assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state image sensor, and the like.

[Table 6]
Example 6

f = 4.33-16.47-61.76
Fno = 3.7-5.1-5.5
Zoom ratio = 14.26

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 31.332 0.70 1.90200 25.1 10.63
2 19.771 3.81 1.49700 81.6 10.10
3 -4091.988 0.12 10.00
4 17.233 2.50 1.72920 54.7 9.63
5 38.818 d1 9.39
6 * 28.727 0.50 1.88300 40.8 4.70
7 4.400 2.50 3.44
8 -17.535 0.50 1.72920 54.7 3.29
9 10.580 0.20 3.18
10 7.368 1.16 1.94590 18.0 3.22
11 19.086 d2 3.10
12 (Aperture) ∞ d3 1.64
13 * 5.359 1.18 1.80610 40.7 2.10
14 * 45.234 0.38 2.07
15 -357.211 0.50 1.72820 28.3 2.04
16 4.500 1.84 1.49710 81.6 1.99
17 * -5.855 d4 2.00
18 33.953 1.23 1.59270 35.5 2.11
19 -6.200 0.39 2.10
20 * -6.432 0.52 1.85130 40.1 2.01
21 * 8.617 d5 2.08
22 * 322.772 2.50 1.49710 81.6 4.01
23 * -8.443 1.58 4.02
24 ∞ 0.30 1.51680 64.2 3.83
25 ∞ 0.50 3.81
26 ∞ 0.50 1.51680 64.2 3.80
27 ∞ 1.07 3.81

Aspheric coefficient

6th surface 20th surface K = 0.00000E + 00 K = 0.00000E + 00
A4 = -0.22606E-03 A4 = -0.18834E-02
A6 = -0.16555E-05 A6 = -0.19765E-06
A8 = 0.88506E-07 A8 = -0.55909E-05
A10 = -0.98969E-09 A10 = 0.33717E-06
A12 = -0.41775E-08

Surface 13 Surface 21 K = 0.00000E + 00 K = 0.00000E + 00
A4 = -0.42022E-03 A4 = -0.14757E-02
A6 = -0.11411E-03 A6 = 0.11871E-03
A8 = -0.21669E-04 A8 = -0.22239E-04
A10 = -0.60300E-06 A10 = 0.15308E-05
A12 = -0.30908E-06 A12 = 0.10329E-07

Surface 14 Surface 22 K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.32837E-03 A4 = 0.83105E-03
A6 = -0.13357E-03 A6 = 0.90945E-04
A8 = -0.47771E-04 A8 = -0.61041E-05
A10 = -0.50470E-06 A10 = 0.20852E-06
A12 = 0.20701E-07 A12 = -0.25996E-08

17th 23rd K = 0.00000E + 00 K = 0.00000E + 00
A4 = 0.18900E-02 A4 = 0.80088E-03
A6 = 0.26351E-04 A6 = -0.17016E-04
A8 = 0.21574E-04 A8 = 0.59899E-05
A10 = 0.22805E-05 A10 = -0.35204E-06
A12 = -0.32749E-06 A12 = 0.72979E-08

Focal length at each position (wide angle, intermediate, telephoto), F number, between groups

F Fno angle of view 2Y d1 d2 d3 d4 d5
4.33 3.70 84.1 6.625 0.49 10.07 0.87 1.79 1.00
16.47 5.10 26.7 7.690 8.96 1.79 1.99 3.49 4.82
61.76 5.50 7.2 7.318 19.44 0.17 1.33 0.40 8.82

Lens group data

Lens group Start surface Focal length (mm)
1 1 30.56
2 6 -4.74
3 13 6.65
4 18 -9.38
5 22 16.59

FIG. 14 is an aberration diagram of Example 6 (spherical aberration, astigmatism, distortion). Here, FIG. 14A is an aberration diagram at the wide-angle end. FIG. 14B is an aberration diagram in the middle. FIG. 14C is an aberration diagram at the telephoto end.

In the zoom lens of Example 6, the first lens group Gr1, the second lens group Gr2, the aperture stop S, the third lens group Gr3, and the fourth lens group Gr4 are arranged in the optical axis direction during zooming from the wide-angle end to the telephoto end. Can be changed by changing the distance between each lens group. The fifth lens group Gr5 is fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the fourth lens L4, the seventh lens L7, the ninth lens L9, the eleventh lens L11, and the twelfth lens L12 are glass mold lenses, and the other lenses are polished lenses made of a glass material.

(Example 7)
Table 7 shows lens data of Example 7. FIG. 15 is a cross-sectional view at the wide-angle end of the zoom lens according to the seventh embodiment. In the drawing, Gr1 is a positive first lens group, and is composed of a negative first lens L1, a positive second lens L2 (L1 and L2 are cemented and the cemented surface is convex on the object side), and a third lens L3. Gr2 is a negative second lens group, a negative fourth lens L4 having a concave surface facing the image side, a negative fifth lens L5 having a concave surface facing the image side, and a positive lens having a convex surface facing the object side. Gr3 is a positive third lens group, and includes a seventh lens (positive 3p1 lens) L7, an eighth lens (negative 3n lens) L8, and a ninth lens (positive 3p2). Lens) L9 (L7, L8, L9 are cemented), Gr4 is a negative fourth lens group, and is composed of a positive tenth lens L10 and a negative eleventh lens L11, and Gr5 is This is a positive fifth lens unit, and is composed of a twelfth lens L12. It is shown. F1 and F2 are parallel flat plates assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state image sensor, and the like.

[Table 7]
Example 7

f = 4.43-16.66-63.24
Fno = 3.7-5.1-5.5
Zoom ratio = 14.26

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 32.503 0.70 1.90200 25.1 10.63
2 20.274 3.65 1.49700 81.6 10.16
3 -979.192 0.12 10.00
4 17.891 2.44 1.72920 54.7 9.66
5 41.815 d1 9.44
6 * 21.895 0.50 1.80420 46.5 4.97
7 4.280 2.90 3.54
8 -14.526 0.50 1.72920 54.7 3.31
9 12.410 0.20 3.21
10 7.079 1.05 1.94590 18.0 3.23
11 13.994 d2 3.10
12 (Aperture) ∞ d3 1.67
13 * 6.629 1.08 1.80610 40.7 2.30
14 -56.698 0.93 1.69890 30.1 2.30
15 4.936 2.30 1.49700 81.6 2.28
16 -6.298 d4 2.35
17 30.784 1.51 1.60340 38.0 2.33
18 -4.833 0.39 2.30
19 * -4.560 0.50 1.88200 37.2 2.10
20 * 10.735 d5 2.19
21 * -72.783 2.50 1.49710 81.6 4.02
22 * -6.878 1.54 4.06
23 ∞ 0.30 1.51680 64.2 3.79
24 ∞ 0.50 3.77
25 ∞ 0.50 1.51680 64.2 3.73
26 ∞ 1.01 3.71

Aspheric coefficient

6th surface 20th surface K = 0.00000E + 00 K = 0.00000E + 00
A4 = -0.24367E-03 A4 = -0.11486E-02
A6 = -0.36029E-05 A6 = 0.14126E-03
A8 = 0.19967E-06 A8 = 0.63747E-04
A10 = -0.28421E-08 A10 = -0.91154E-05
A12 = -0.13486E-10

Surface 13 Surface 21 K = 0.00000E + 00 K = 0.00000E + 00
A4 = -0.10785E-02 A4 = 0.14809E-02
A6 = 0.29286E-04 A6 = 0.11358E-03
A8 = -0.19943E-04 A8 = -0.90329E-05
A10 = 0.35758E-05 A10 = 0.24506E-06
A12 = -0.24107E-06 A12 = -0.10828E-08

19th surface 22nd surface K = 0.00000E + 00 K = 0.00000E + 00
A4 = -0.30056E-02 A4 = 0.61883E-03
A6 = 0.72628E-04 A6 = 0.64936E-04
A8 = 0.10322E-03 A8 = 0.19637E-05
A10 = -0.14783E-04 A10 = -0.37579E-06
A12 = 0.57315E-11 A12 = 0.11229E-07

Focal length at each position (wide angle, intermediate, telephoto), F number, between groups

F Fno angle of view 2Y d1 d2 d3 d4 d5
4.44 3.70 82.7 6.855 0.32 10.12 1.17 2.22 0.99
16.66 5.10 26.4 7.267 10.15 2.95 2.20 3.00 5.66
63.24 5.50 7.1 7.107 19.96 1.28 0.22 1.00 7.02

Lens group data

Lens group Start surface Focal length (mm)
1 1 31.00
2 6 -4.77
3 13 6.88
4 17 -8.78
5 21 15.09

FIG. 16 is an aberration diagram of Example 7 (spherical aberration, astigmatism, distortion). Here, FIG. 16A is an aberration diagram at the wide-angle end. FIG. 16B is an aberration diagram in the middle. FIG. 16C is an aberration diagram at the telephoto end.

In the zoom lens of Example 7, the first lens group Gr1, the second lens group Gr2, the aperture stop S, the third lens group Gr3, and the fourth lens group Gr4 are arranged in the optical axis direction during zooming from the wide angle end to the telephoto end. Can be changed by changing the distance between each lens group. The fifth lens group Gr5 is fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the fourth lens L4, the seventh lens L7, the ninth lens L9, the eleventh lens L11, and the twelfth lens L12 are glass mold lenses, and the other lenses are polished lenses made of a glass material.

Table 8 summarizes the values of the conditional expressions described in the claims.

Recently, it has been found that by mixing inorganic fine particles in a plastic material, the temperature change of the plastic material can be reduced. More specifically, when fine particles are mixed with a transparent plastic material, light scattering occurs and the transmittance is lowered. Therefore, it has been difficult to use as an optical material. By making it smaller than the wavelength, it is possible to substantially prevent scattering. The refractive index of the plastic material decreases with increasing temperature, but the refractive index of inorganic particles increases with increasing temperature. Therefore, it is possible to make almost no change in the refractive index by using these temperature dependencies so as to cancel each other. Specifically, by dispersing inorganic particles having a maximum length of 20 nanometers or less in a plastic material as a base material, a plastic material with extremely low temperature dependence of the refractive index is obtained. For example, by dispersing fine particles of niobium oxide (Nb ₂ O ₅ ) in acrylic, the refractive index change due to temperature change can be reduced. In the present invention, by using a plastic material in which such inorganic particles are dispersed for the twelfth lens of Example 3, it is possible to further suppress the image point position fluctuation at the time of temperature change of the entire zoom lens system. Become.

In recent years, as a method for mounting a large number of image pickup devices at low cost, a reflow process (heating process) is performed on a substrate on which solder is previously potted while an IC chip or other electronic component and an optical element are placed on the substrate. A technique has been proposed in which an electronic component and an optical element are simultaneously mounted on a substrate by melting solder.

In order to perform mounting using such a reflow process, it is necessary to heat the optical element to about 200 to 260 degrees together with the electronic components. At such a high temperature, a lens using a thermoplastic resin is thermally deformed. However, there is a problem that the optical performance deteriorates due to discoloration. As one of the methods for solving such a problem, a technology has been proposed that uses a glass mold lens having excellent heat resistance and achieves both miniaturization and optical performance in a high temperature environment. Since the cost is higher than the lens used, there is a problem that it is difficult to meet the demand for cost reduction of the imaging device.

Therefore, by using an energy curable resin as the material of the zoom lens, the optical performance degradation when exposed to high temperatures is small compared to lenses using thermoplastic resins such as polycarbonate and polyolefin, It is effective for the reflow process, is easier to manufacture than a glass mold lens, is inexpensive, and can achieve both low cost and mass productivity of an imaging apparatus incorporating a zoom lens. The energy curable resin refers to both a thermosetting resin and an ultraviolet curable resin. You may form the plastic lens of this invention also using the above-mentioned energy curable resin.

The present invention is not limited to the embodiments described in the specification, and other embodiments and modifications are apparent to those skilled in the art from the embodiments and ideas described in the present specification. It is. For example, even when a dummy lens having substantially no power is further provided, it is within the scope of the present invention.

71 Tripod hole 72 Card cover 80 Lens barrel 81 Camera body 82 Viewfinder window 83 Release button 84 Flash light emitting part 87 Strap attaching part 88 USB terminal 89 Lens cover 91 Viewfinder eyepiece 92 Display lamp 93 Zoom button 95 Set button 96 Four directions Switch 96 Selection button 97 Playback button 98 Display button 99 Erase button 100 Imaging device 101 Zoom lens 102 Solid-state imaging device 103 Conversion unit 104 Control unit 105 Optical system driving unit 106 Timing generation unit 107 Imaging device driving unit 108 Image memory 109 Image processing unit 110 Image compression unit 111 Image recording unit 112 Monitor LCD
113 Operation unit DC Digital camera Gr1 to Gr5 Lens group L1 to L12 Lens S Aperture stop I Imaging surface F1, F2 Optical low-pass filter or IR cut filter

Claims (12)

In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a negative refractive power In a zoom lens that includes a group and a fifth lens group having a positive refractive power, and performs zooming by changing the interval between the lens groups,
The fourth lens group includes, in order from the object side, a positive lens and a negative lens. The positive lens and the negative lens are spaced apart from each other by air, and satisfy the following conditional expression.
−0.30 <f4 / fT <−0.05 (1)
0.1 <Pair4 / P4 <1.5 (2)
However,
Pair 4: The refractive power P4 of the so-called air lens formed by the positive lens image side surface of the fourth lens group and the negative lens object side surface of the fourth lens group: the refractive power f4 of the fourth lens group: the first lens Focal length fT of the four lens groups: focal length of the entire system at the telephoto end Pair 4 is given by the following [Equation 1].

However,
n ₄₁ : refractive index with respect to d-line of positive lens of the fourth lens group n ₄₂ : refractive index with respect to d-line of negative lens of the fourth lens group R ₄₂ : curvature of image side surface of positive lens of the fourth lens group Radius R ₄₃ : Radius of curvature of the object side surface of the negative lens of the fourth lens group D ₄ : Air spacing on the axis of the positive lens of the fourth lens group and the negative lens of the fourth lens group 2. The zoom lens according to claim 1, wherein the third lens group includes, in order from the object side, a positive 3p1 lens, a negative 3n lens, and a positive 3p2 lens, and satisfies the following conditional expression: .
0.15 <n3n-n3p2 <0.50 (3)
30 <ν3p2-ν3n <60 (4)
However,
n3n: refractive index of the 3n lens n3p2: refractive index of the 3p2 lens ν3p2: Abbe number of the 3p2 lens ν3n: Abbe number of the 3n lens The second lens group includes, in order from the object side, a negative lens having a concave surface facing the image side, a negative lens having a concave surface facing the image side, and a positive lens having a convex surface facing the object side. The zoom lens according to claim 1 or 2. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
_{0.2 <n 42 - n 41 <} 0.4 (5) The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
1.50 <f1 / (fW × fT) ^1/2 <2.50 (6)
−0.20 <f2 / (fW × fT) ^1/2 <−0.40 (7)
However,
f1: focal length of the first lens group f2: focal length of the second lens group fW: focal length of the entire system at the wide-angle end fT: focal length of the entire system at the telephoto end The first lens group includes, in order from the object side, a cemented lens including one negative lens and one positive lens. The cemented surface of the cemented lens is convex on the object side, and the following conditional expression is satisfied. The zoom lens according to claim 1, wherein the zoom lens is satisfied.
0.3 <n1N-n1P <0.6 (8)
However,
n1N: refractive index with respect to d-line of the negative lens in the cemented lens of the first lens group n1P: refractive index with respect to d-line of the positive lens in the cemented lens of the first lens group The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
1.5 <(D1 + D2) / fW <3.0 (9)
However,
D1: Thickness on the optical axis of the first lens group D2: Thickness on the optical axis of the second lens group fW: Focal length of the entire system at the wide angle end The zoom lens according to any one of claims 1 to 7, wherein the fifth lens group does not move in the optical axis direction at the time of zooming and focusing. The zoom lens according to claim 1, wherein the fifth lens group is a single lens. The zoom lens according to any one of claims 1 to 9, wherein the zoom lens performs focusing by moving the fourth lens group. The zoom lens according to any one of claims 1 to 10, further comprising a lens having substantially no power. An image pickup apparatus comprising the zoom lens according to any one of claims 1 to 11.

Images