JP5713777B2 - Zoom lens and imaging apparatus having the same - Google Patents

Description

  The present invention relates to a zoom lens, and is suitable for an imaging apparatus such as a digital still camera, a video camera, a surveillance camera, and a TV camera.

  Recently, an imaging optical system used in an imaging apparatus using a solid-state imaging element is required to be a bright (large aperture ratio) zoom lens having a wide angle of view capable of photographing a wide range of a subject. As a zoom lens that can easily shoot a wide angle of view, a negative lead type zoom lens that is preceded by a lens unit having a negative refractive power (located closest to the object side) is known. As a negative lead type zoom lens, in order from the object side to the image side, three groups including 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 Zoom lenses are known (Patent Documents 1 and 2).

  Patent Document 1 discloses a zoom lens having a shooting half angle of view of 22 degrees at the wide-angle end, an F-number of about 1.0 at the wide-angle end, and an F-number of about 1.7 at the telephoto end. Patent Document 1 discloses a zoom lens with good telecentricity having a light beam incident angle (the maximum angle in the entire zoom range among the angles when the off-axis principal ray is incident on the image plane) of about 3.8 degrees. . Patent Document 2 discloses a zoom lens having a good telecentricity with a shooting half field angle at the wide-angle end of 29 degrees, an F-number of 3.0 at the wide-angle end, an F-number of 4.9 at the telephoto end, and a light incident angle of about 4.2 degrees. Disclosure.

JP-A-1-046717 JP 2004-318101 A

  In recent years, zoom lenses used in video cameras, digital cameras, and the like are strongly demanded to have a large aperture ratio, a wide angle of view, and a small incident angle of light. In the above-described three-group zoom lens, in order to increase the aperture ratio (F number: about 2.5), widen the angle of view (shooting angle of view: about 70 degrees), and reduce the light incident angle, each lens group is refracted. It is important to set the force and lens configuration appropriately. In particular, it is important to appropriately set the lens configuration of the second lens unit having a positive refractive power, the power (refractive power) of the third lens unit, the length of the back focus, and the like.

  If these elements are inappropriate, it becomes difficult to increase the aperture ratio, widen the angle of view, and reduce the light incident angle while maintaining high optical performance.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a zoom lens that has a large aperture ratio, a wide angle of view, a small incident angle of light, and high optical performance, and an imaging apparatus having the same.

The zoom lens according to the present invention 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 including an aperture stop, and a third lens group having a positive refractive power. In this zoom lens, the distance between adjacent lens groups changes during zooming, and the third lens group moves during focusing. The second lens group includes two or more positive lenses in order from the object side to the image side. And the third lens unit has a focal length of f3, the focal lengths of the entire system at the wide-angle end and the telephoto end are fw and ft, respectively, and the F-numbers at the wide-angle end and the telephoto end are Fnow, Fnot, the air equivalent distance from the final lens surface to the image plane at the telephoto end is BFt , the positive lens disposed closest to the object side of the second lens group, and the position adjacent to the image side of the positive lens Positive ren When the focal lengths of f are f21 and f22 respectively ,
0.20 <Fnow * fw / f3 <0.43
0.4 <BFt * Fnot / ft <0.9
2.0 <f21 / f22 <4.0
It satisfies the following conditional expression.

  According to the present invention, it is possible to obtain a zoom lens having a large aperture ratio, a wide angle of view, a small incident angle, and high optical performance.

Lens sectional view of Numerical Example 1 of the present invention (A), (B) Aberration diagrams at the wide-angle end and the telephoto end of Numerical Example 1 of the present invention. Lens sectional view of Numerical Example 2 of the present invention (A), (B) Aberration diagrams at the wide-angle end and at the telephoto end of Numerical Example 2 of the present invention. Lens sectional view of Numerical Example 3 of the present invention (A), (B) Aberration diagrams at the wide-angle end and the telephoto end of Numerical Example 3 of the present invention. Lens sectional view of Numerical Example 4 of the present invention (A), (B) Aberration diagrams at the wide-angle end and the telephoto end of Numerical Example 4 of the present invention. Lens sectional view of Numerical Example 5 of the present invention (A), (B) Aberration diagrams at the wide-angle end and at the telephoto end according to Numerical Example 5 of the present invention. Schematic diagram of main parts of an imaging apparatus of the present invention

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The zoom lens according to the present invention 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 including an aperture stop, and a third lens group having a positive refractive power. Has been. Each lens group moves during zooming. Specifically, during zooming from the wide-angle end to the telephoto end, the first, second, and third lens groups are narrowed while the distance between the first lens group and the second lens group is narrowed and the distance between the second lens group and the third lens group is widened. The third lens group moves. During focusing, the third lens group moves.

  FIG. 1 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to the first exemplary embodiment of the present invention. FIGS. 2A and 2B are aberration diagrams at the wide-angle end and the telephoto end (long focal length end), respectively, of the zoom lens according to the first exemplary embodiment. Example 1 is a zoom lens having a zoom ratio of 2.37 and an aperture ratio of about 1.80 to 3.30. FIG. 3 is a lens cross-sectional view at the wide-angle end of the zoom lens according to the second embodiment of the present invention. 4A and 4B are aberration diagrams of the zoom lens of Example 2 at the wide-angle end and the telephoto end, respectively. The second exemplary embodiment is a zoom lens having a zoom ratio of 2.37 and an aperture ratio of about 2.33 to 3.60.

  FIG. 5 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 3 of the present invention. 6A and 6B are aberration diagrams of the zoom lens of Example 3 at the wide-angle end and the telephoto end, respectively. The third embodiment is a zoom lens having a zoom ratio of 2.72 and an aperture ratio of about 2.06 to 3.60. FIG. 7 is a lens cross-sectional view at the wide-angle end of the zoom lens according to the fourth exemplary embodiment of the present invention. 8A and 8B are aberration diagrams of the zoom lens of Example 4 at the wide-angle end and the telephoto end, respectively. Example 4 is a zoom lens having a zoom ratio of 2.37 and an aperture ratio of about 1.40 to 2.71.

  FIG. 9 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Example 5 of the present invention. FIGS. 10A and 10B are aberration diagrams of the zoom lens of Example 5 at the wide-angle end and the telephoto end, respectively. The fifth embodiment is a zoom lens having a zoom ratio of 2.72 and an aperture ratio of about 2.06 to 3.60. FIG. 11 is a schematic diagram of a main part of a digital camera provided with the zoom lens of the present invention.

  The zoom lens of each embodiment is a photographic lens system used in an imaging apparatus. In the lens cross-sectional view, the left side is the subject side (front side) (object side), and the right side is the image side (rear side). In the lens cross-sectional view, L1 is a first lens group having negative refractive power (optical power = reciprocal of focal length), L2 is a second lens group having positive refractive power, and L3 is a third lens group having positive refractive power. It is.

  SP is an F number determining member (hereinafter also referred to as “aperture stop”) that functions as an aperture stop that determines (limits) an open F number (Fno) light beam. The aperture stop SP is disposed between the lenses of the second lens unit L2. G is an optical block corresponding to an optical filter, a face plate, a quartz low-pass filter, an infrared cut filter, or the like. IP is an image plane, and when used as a photographing optical system of a video camera or a digital still camera, an imaging plane of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is placed. Further, when used as a photographing optical system for a silver salt film camera, a photosensitive surface corresponding to the film surface is provided. The * mark attached to the lens surface indicates that the lens surface is aspherical.

  In the aberration diagrams, the solid line of spherical aberration is represented by d line, the two-dot chain line is represented by g line, the solid line of astigmatism is represented by meridional image surface ΔM, the broken line is represented by sagittal image surface ΔS, and the lateral chromatic aberration is represented by g line. Fno represents an F number, and ω represents a shooting half angle of view (degrees).

In the zoom lens of each embodiment, during zooming from the wide-angle end to the telephoto end zoom position, the first lens unit L1 substantially reciprocates along a locus convex toward the image side. Further, the second lens unit L2 moves to the object side. The third lens unit L3 moves monotonously on the image side or moves along a convex locus on the image side. At this time, zooming is performed such that the distance between the first lens unit L1 and the second lens unit L2 at the telephoto end is smaller than that at the wide-angle end, and the interval between the second lens unit L2 and the third lens unit L3 is increased. ing. That is, the interval between adjacent lens groups changes during zooming. The zoom lens of each embodiment performs main zooming by moving the second lens unit L2, and the image point associated with zooming by the reciprocating movement of the first lens unit L1 or the first and third lens units L1 and L3. The movement is corrected.

Securing the back focus of the required length with miniaturized wide angle of view and the front Tamayu Ko径With negative refractive power arrangement of refracting power proactive the first lens unit L1 as a negative refractive power doing. Further, the third lens unit L3 is set to have a positive refractive power so that the exit pupil is sufficiently away from the image plane, and the incident angle (light beam incident angle) of the light beam incident on the solid-state imaging device is relaxed. This reduces shading that occurs on the solid-state image sensor. The light ray incident angle represents the maximum angle in the entire zoom range among the angles at which the principal ray is incident on the image plane.

  Focusing from an infinitely distant object to a close object is performed by moving the third lens unit L3 to the object side. The F-number determining member SP is disposed between the lenses of the second lens unit L2 with respect to the optical axis direction. By arranging the aperture stop SP at such a position, the distance between the first lens unit L1 and the second lens unit L2 at the telephoto end is reduced, and the total lens length is shortened.

  In the three-group zoom lens of each embodiment, an attempt is made to achieve a wide-angle zoom lens having a large aperture (about F-number 2.0 at the wide-angle end) and a large shooting angle of view at the wide-angle end (more than 70 ° shooting angle of view). Then, as a side effect, the power (refractive power) of the lens near the aperture stop increases. As a result, it becomes difficult to maintain good imaging performance. In a zoom lens having a large aperture and a wide field angle, in order to obtain high optical performance over the entire object distance, it is important to appropriately perform the light incident condition and focusing on each lens group.

  In each embodiment, the power of the first and third lens units L1 and L3 is appropriately set to widen the angle of view, and the lens configuration in the second lens unit L2 near the aperture stop SP is appropriately set. , Achieving a large aperture. In addition, by appropriately defining the power of the third lens unit L3 and the air conversion distance (back focus) from the final lens to the image plane, fluctuations in aberrations when focusing with the third lens unit L3 are reduced. .

  In each embodiment, the second lens unit L2 includes two or more positive lenses and one or more negative lenses in order from the object side to the image side. Let the focal length of the third lens unit L3 be f3. The focal lengths of the entire system at the wide-angle end and the telephoto end are denoted by fw and ft, respectively. The F-numbers at the wide-angle end and the telephoto end are Fnow and Fnot, respectively. Let BFt be the air-converted distance from the final lens surface to the image plane at the telephoto end.

At this time,
0.20 <Fnow * fw / f3 <0.43 (1)
0.4 <BFt * Fnot / ft <0.9 (2)
The following conditional expression is satisfied .

  In each embodiment, by satisfying the conditional expressions (1) and (2) as described above, the incident angle to the image sensor (photosensitive surface) is reduced, and the half angle of view at the wide angle end is large and large. Achieving a caliber zoom lens.

Conditional expression (1) defines a power range of the third lens unit L3 that is preferable for focusing by the third lens unit L3. If the lower limit of conditional expression (1) is not reached, the power of the third lens unit L3 becomes small, and the amount of extension is excessively increased during focusing, which is not preferable. The Beyond the upper limit becomes too large power of the third lens unit L3, the first when's Mingu in the first lens unit L1 power of the second lens unit L2 is smaller, the second lens group L1, L2 Since the movement amount increases, it is not preferable.

  Conditional expression (2) defines the range of the air conversion distance (back focus) from the final lens surface to the image plane under the power of the third lens unit L3 defined in conditional expression (1). Exceeding the upper limit is not preferable because the back focus increases, the zoom lens increases, and the payout amount during focusing decreases from the distance from the second lens unit L2. If the value is below the lower limit, the back focus becomes small, and it is difficult to appropriately arrange an image sensor, a high frequency cut filter, and the like, which is not preferable.

More preferably, the numerical ranges of conditional expressions (1) and (2) are set as follows.
0.205 <Fnow * fw / f3 <0.430 (1a)
0.42 <BFt * Fnot / ft <0.90 (2 a )
As described above, according to each embodiment, the focal length of the third lens unit L3, the lens configuration of the second lens unit L2, the F number at the wide-angle end and the telephoto end, and the like are appropriately set, thereby reducing the size of the entire system. The zoom lens has a wide angle of view with various aberrations corrected well. In each embodiment, it is more preferable that one or more of the following conditions be satisfied.

The radius of curvature of the lens surface on the image side of the first first positive lens (the positive lens disposed closest to the object side) counted from the object side of the second lens unit L2 is R21b. Let R22a be the radius of curvature of the object-side lens surface of the second second positive lens (positive lens arranged at a position adjacent to the image side of the first positive lens). The focal lengths of the first positive lens and the second positive lens are f21 and f22, respectively. Let the focal length of the first lens unit L1 be f1. At this time,
−2.0 <(R22a + R21b) / (R22a−R21b) <0.0 (3)
2.0 <f21 / f22 <4.0 (4)
-1.6 <Fnow * fw / f1 <-0.5 (5)
It is preferable to satisfy one or more of the following conditional expressions.

  Conditional expression (3) relates to the shape of the air lens formed by the first positive lens and the second positive lens, and is for correcting coma aberration at the periphery of the screen that occurs when the aperture is increased. When the upper limit of conditional expression (3) is exceeded, the radius of curvature of the object-side lens surface of the second positive lens becomes close to the radius of curvature of the image-side lens surface of the first positive lens. Since it becomes difficult to perform power sharing appropriately, it is not preferable. If the lower limit is not reached, the radius of curvature of the image side lens surface of the first positive lens becomes larger than the radius of curvature of the object side lens surface of the second positive lens, and the coma aberration correcting effect by the air lens is reduced. Therefore, it is not preferable.

More preferably, the numerical range of conditional expression (3) is set as follows.
−1.8 <(R22a + R21b) / (R22a−R21b) <0.0 (3a)
Conditional expression (4) relates to the power ratio of the first and second first and second positive lenses counted from the object side constituting the second lens unit L2. Exceeding the upper limit of conditional expression (4) is not preferable because the power of the second positive lens becomes strong and it becomes difficult to correct coma at the periphery of the screen. On the other hand, if the value is below the lower limit, the power of the first positive lens becomes strong and it becomes difficult to correct coma aberration, which is not preferable.

If the configuration of the second lens unit L2 is composed of, for example, one positive lens and one negative lens, the power of the second lens unit L2 becomes stronger when the angle of view is widened and the aperture is increased. Will increase. In addition, when the number of positive lenses is one, the degree of freedom of the lens shape is small, so that it is difficult to correct spherical aberration and coma at the periphery of the screen.

  Therefore, in each embodiment, the second lens unit L2 is composed of two or more positive lenses and one or more negative lenses in order from the object side, thereby increasing the degree of freedom of the lens shape and appropriately sharing the power of the positive lens. ing. Specifically, by setting the shape of the first and second positive lenses so as to satisfy the conditional expression (3) and setting the power sharing of the positive lens so as to satisfy the conditional expression (4), the diameter of the lens can be increased. The coma and spherical aberration are corrected well when the angle of view is changed.

  Conditional expression (5) relates to the power of the first lens unit L1, and the power arrangement of the zoom lens specified in conditional expressions (1) and (2) is set more appropriately, making it easy to widen the angle of view and increase the aperture. It is for making.

Exceeding the upper limit of conditional expression (5) is not preferable because the power of the first lens unit L1 becomes too strong, and particularly distortion and lateral chromatic aberration increase. If the value is below the lower limit, the power of the first lens unit L1 becomes weak, and it is difficult to increase the angle of view, which is not preferable. More preferably, the numerical range of conditional expression (5) is set as follows.
−1.5 <Fnow * fw / f1 <−0.6 (5a)
In each embodiment, the third lens unit L3 may be composed of one positive lens or a cemented lens in which a positive lens and a negative lens are cemented. This makes it easy to reduce the size and weight of the focus lens group. If the focus lens group is lightweight, the time until focusing is generally shortened, which is advantageous when shooting a moving subject or a momentary scene.

  The aperture stop SP is disposed between the lenses of the second lens unit L2, and the combined refractive power of the lenses disposed on the image side of the aperture stop SP in the second lens unit L2 is positive. As a result, various aberrations generated from the second lens unit L2 are reduced.

  According to the present invention, the light incident angle to the image sensor is 18 ° or less with a large aperture of 2.4 or less at the F number at the wide angle end and 3.8 or less at the F number at the telephoto end. A zoom lens having a wide angle of view with a shooting half angle of view of 36 ° or more at the wide angle end is reduced. Hereinafter, the lens configuration of each example will be described.

Example 1
The lens configuration of Example 1 in FIG. 1 will be described. The first exemplary embodiment includes, in order from the object side to the image side, a first lens unit L1 having a negative refractive power, a second lens unit L2 having a positive refractive power, and a third lens unit L3 having a positive refractive power. . The aperture stop SP is included in the second lens unit L2. During zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves along a locus in which the image has a convex shape. The second lens unit L2 moves to the object side, and the third lens unit L3 moves to the image side.

  Focusing is performed by moving the third lens unit L3. The second lens unit L2 includes, in order from the object side to the image side, a positive lens, a positive lens, a positive lens, a negative lens, a negative lens, an aperture stop SP, and a cemented lens in which a positive lens and a negative lens are cemented. The lens configuration includes three positive lenses and two negative lenses in order from the object side. When the angle of view is increased, the focal length of the second lens unit L2 is shortened and the power of the lenses in the second lens unit L2 is increased. When the diameter is increased, the effective diameter of the lens in the vicinity of the aperture stop SP increases, and if the radius of curvature of the lens surface is small, generally the aberration at the periphery of the screen tends to increase dramatically. Therefore, it is preferable that the power of the lens near the aperture stop SP is as small as possible.

  In this embodiment, the power of each lens is reduced by using three positive lenses, the power sharing of each lens is appropriately performed, and the coma aberration accompanying the increase in the diameter is corrected by appropriately setting the lens shape. doing. In this embodiment, the aperture stop SP is disposed inside the second lens unit L2. As a result, the light beam diverged by the first lens unit L1 is converged by the positive lens on the object side of the second lens unit L2, is diverged by the negative lens and becomes substantially afocal, and is converged by the third lens unit L3 to be image plane. To form an image.

  Therefore, when the aperture stop SP is disposed between the first lens unit L1 and the second lens unit L2, the effective diameter of the aperture increases because the light speed diverged by the first lens unit L1 is incident. If the zoom lens has a large F number Fno, the increase in the effective aperture diameter is not affected so much. However, in the large-aperture zoom lens as in the present embodiment, the effective aperture diameter is large. This is not preferable because it leads to an increase in the size of the imaging device or the like. Therefore, by disposing the second lens unit L2 closer to the image side than the positive lens, the effective aperture diameter is reduced while the aperture is large, thereby reducing the size of the imaging apparatus.

In this embodiment, the wide-angle end F number Fno is 1.8, and the telephoto end F number Fno is 3.3. The light incident angle on the image plane is reduced by appropriately arranging the power of the third lens unit L3. Note that the negative distortion at the wide-angle end may be corrected by electronic image processing .

(Example 2)
The lens configuration of Example 2 in FIG. 3 will be described. The zoom type and focusing method of the zoom lens of the second embodiment are the same as those of the first embodiment. The lens configuration of the second lens unit L2 is the same as that of the first embodiment. The wide angle of view, the large aperture, the reduction of the light incident angle, and the like are the same as in the first embodiment.

(Example 3)
The lens configuration of Example 3 in FIG. 5 will be described. The third exemplary embodiment includes, in order from the object side to the image side, a first lens unit L1 having a negative refractive power, a second lens unit L2 having a positive refractive power, and a third lens unit L3 having a positive refractive power. . The aperture stop SP is disposed in the second lens unit L2. During zooming from the wide-angle end to the telephoto end, the first and third lens units L1 and L3 move along a locus that is convex toward the image side. The second lens unit L2 moves to the object side. Focusing is performed by moving the third lens unit L3.

  The wide angle of view, the large aperture, the reduction of the light incident angle, etc. are the same as in the first embodiment. The second lens unit L2 includes, in order from the object side to the image side, a positive lens, a positive lens, a negative lens, an aperture stop SP, and a positive lens. The lens configuration includes two positive lenses, one negative lens, and one positive lens from the object side. By reducing the number of lenses in the second lens unit L2, coma and spherical aberration are corrected by using aspherical surfaces for the positive and negative lenses, and various aberrations at the periphery of the screen are corrected well. Yes. In this embodiment, the thickness of the second lens unit L2 is reduced by reducing the number of lenses of the second lens unit L2.

Example 4
The lens configuration of Example 4 in FIG. 7 will be described. The zoom type and focusing method of the zoom lens of Example 4 are the same as those of Example 1. The wide angle of view, the large aperture, the reduction of the light incident angle, and the like are the same as in the first embodiment. The second lens unit L2 includes, in order from the object side to the image side, a positive lens, a positive lens, a positive lens, a negative lens, an aperture stop, and a cemented lens in which a positive lens and a negative lens are cemented. The configuration is three positive lenses, one negative lens, and a cemented lens. In this embodiment, the F-number at the wide angle end is as bright as 1.4.

(Example 5)
The lens configuration of Example 5 in FIG. 9 will be described. The zoom type and focusing method of the zoom lens of Example 5 are the same as those of Example 3. The wide angle of view, the large aperture, the reduction of the light incident angle, etc. are the same as in the first embodiment. The lens configuration of the second lens unit L2 is the same as that of the third embodiment. This embodiment achieves a wide angle of view with a large aperture and a shooting half angle of view of about 37 degrees at the wide angle end. In each embodiment, camera shake correction may be performed by moving an arbitrary lens group in a direction perpendicular to the optical axis to displace the imaging position.

Next, numerical examples of the respective embodiments of the present invention will be shown. In each numerical example, i indicates the order of the surfaces from the object side. In the numerical examples, ri is the radius of curvature of the i-th lens surface in order from the object side. di is the i-th lens thickness and air spacing in order from the object side. ndi and νdi are respectively the refractive index and Abbe number for the d-line of the i-th material in order from the object side. The aspherical shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, K is the conic constant, A4, A6, A8, A10, A12 , A14 Each as an aspheric coefficient

It is expressed by the following formula. [E + X] means [× 10 + x], and [e-X] means [× 10-x]. BF is the distance from the final surface (image side surface of the glass block G) to the paraxial image surface. The total lens length is obtained by adding the distance BF to the distance from the lens front surface to the final surface. An aspherical surface is indicated by adding * after the surface number. Table 1 shows the shooting half angle of view (degrees) at the wide-angle end, the F number at the wide-angle end and the telephoto end, and the light incident angle (degree) in each example. Table 2 shows the relationship between the above-described conditional expressions and numerical examples.

(Numerical example 1)
Unit mm
Surface data surface number rd nd νd Effective diameter
1 * 38.092 1.79 1.80400 46.6 27.30
2 * 12.182 7.00 22.01
3 -49.521 1.30 1.80400 46.6 21.78
4 1001.106 0.16 21.83
5 33.884 2.44 2.01960 21.5 21.94
6 96.924 (variable) 21.56
7 400.000 1.80 1.88300 40.8 17.54
8 -80.000 0.04 17.72
9 15.532 2.30 1.88300 40.8 17.98
10 29.784 0.16 17.54
11 * 14.934 3.30 1.59240 68.3 16.82
12 32.444 0.90 15.41
13 22.599 0.81 1.92286 18.9 14.31
14 10.453 2.93 12.80
15 43.072 1.05 1.80 100 35.0 12.51
16 21.584 1.96 12.12
17 (Aperture) ∞ 1.10 12.10
18 * 30.147 3.00 1.80400 46.6 12.08
19 -27.269 0.80 1.80610 33.3 11.76
20 -65.282 (variable) 11.67
21 21.412 3.30 1.48749 70.2 21.72
22 53.046 (variable) 21.51
23 ∞ 2.73 1.51633 64.1 36.07
24 ∞ 1.46 36.07
Image plane ∞

Aspheric data 1st surface
K = 0.00000e + 000 A 4 = -6.46526e-005 A 6 = 3.78456e-007 A 8 = -9.53194e-010
A10 = -1.63322e-012 A12 = 1.82150e-014 A14 = -3.87131e-017

Second side
K = -1.25737e + 000 A 4 = -1.49004e-005 A 6 = 2.03486e-007 A 8 = 4.28089e-009
A10 = -6.21944e-011 A12 = 4.54644e-013 A14 = -1.34923e-015

11th page
K = -4.06303e-001 A 4 = -1.25288e-005 A 6 = 1.30352e-008 A 8 = 1.93763e-011
A10 = -3.60096e-011 A12 = 6.19231e-013 A14 = -3.33094e-015

18th page
K = 6.35103e + 000 A 4 = -2.95961e-005 A 6 = -5.59963e-007 A 8 = 1.20780e-008
A10 = -1.58962e-010

Various data Zoom ratio 2.37

Focal length 14.20 23.82 33.60 18.94 28.74
F number 1.80 2.55 3.30 2.17 2.93
Angle of view 37.13 24.29 17.74 29.58 20.51
Image height 10.75 10.75 10.75 10.75 10.75
Total lens length 77.26 73.75 77.74 73.93 75.24
BF 1.46 1.46 1.46 1.46 1.46

d 6 20.81 7.03 0.76 12.35 3.40
d20 12.51 24.25 34.60 18.55 29.60
d22 3.61 2.13 2.04 2.70 1.91

Entrance pupil position 18.49 16.95 16.02 17.61 16.43
Exit pupil position -27.10 -48.90 -82.42 -36.83 -63.86
Front principal point position 25.63 29.50 36.16 27.18 32.52
Rear principal point position -12.74 -22.36 -32.14 -17.49 -27.28

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -25.32 12.69 0.90 -9.39
2 7 23.27 20.15 3.14 -15.24
3 21 71.22 3.30 -1.45 -3.60


Single lens Data lens Start surface Focal length
1 1 -22.98
2 3 -58.66
3 5 50.12
4 7 75.63
5 9 34.17
6 11 43.65
7 13 -21.77
8 15 -55.21
9 18 18.23
10 19 -58.65
11 21 71.22
12 23 0.00

(Numerical example 2)
Unit mm
Surface data surface number rd nd νd Effective diameter
1 * 43.797 1.79 1.80 400 46.6 26.88
2 * 12.368 7.00 21.57
3 -47.887 1.30 1.80 400 46.6 21.38
4 -1155.809 0.16 21.52
5 31.334 2.44 2.01960 21.5 21.70
6 77.808 (variable) 21.30
7 -661.553 1.50 1.65160 58.5 13.78
8 -55.322 0.04 14.04
9 19.722 2.30 1.69680 55.5 14.45
10 126.677 0.16 14.24
11 * 12.048 3.60 1.69680 55.5 13.72
12 24.080 0.90 12.21
13 28.778 0.81 1.80518 25.4 11.66
14 9.173 2.93 10.52
15 43.072 1.05 1.80610 33.3 10.47
16 21.584 1.96 10.30
17 (Aperture) ∞ 1.10 10.53
18 * 32.094 3.00 1.80 400 46.6 10.80
19 -18.410 0.80 1.80610 33.3 10.70
20 -60.132 (variable) 10.62
21 27.803 3.30 1.48749 70.2 21.07
22 97.657 (variable) 21.04
23 ∞ 2.73 1.51633 64.1 36.07
24 ∞ 1.48 36.07
Image plane ∞

Aspheric data 1st surface
K = 0.00000e + 000 A 4 = -4.73699e-005 A 6 = 3.14578e-007 A 8 = -8.99102e-010
A10 = -2.55306e-013 A12 = 5.05769e-015 A14 = -4.91644e-018

Second side
K = -1.01349e + 000 A 4 = -8.97969e-006 A 6 = 2.40896e-007 A 8 = 2.14985e-009
A10 = -1.20553e-011 A12 = -1.53484e-014 A14 = 9.20599e-017

11th page
K = -4.77208e-001 A 4 = 2.44578e-005 A 6 = 7.32471e-008 A 8 = 1.51705e-009
A10 = 1.23094e-011 A12 = -4.41484e-013 A14 = 3.12571e-015

18th page
K = 7.85377e + 000 A 4 = -3.20955e-005 A 6 = -9.64357e-008 A 8 = -4.15401e-009
A10 = 6.55633e-011

Various data Zoom ratio 2.37

Focal length 14.20 23.83 33.60 18.95 28.74
F number 2.33 2.97 3.60 2.65 3.29
Angle of view 37.13 24.28 17.74 29.56 20.51
Image height 10.75 10.75 10.75 10.75 10.75
Total lens length 77.14 73.70 77.78 73.84 75.24
BF 1.48 1.48 1.48 1.48 1.48

d 6 21.36 7.66 1.48 12.93 4.07
d20 11.27 23.01 33.36 17.31 28.36
d22 4.16 2.68 2.58 3.24 2.46

Entrance pupil position 18.33 16.95 16.15 17.54 16.50
Exit pupil position -25.73 -45.34 -73.50 -34.62 -58.19
Front principal point position 25.12 28.66 34.69 26.54 31.40
Rear principal point position -12.72 -22.35 -32.12 -17.48 -27.26

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -24.82 12.69 0.72 -9.58
2 7 23.13 20.15 2.39 -15.90
3 21 78.52 3.30 -0.87 -3.05


Single lens Data lens Start surface Focal length
1 1 -21.99
2 3 -62.17
3 5 50.12
4 7 92.56
5 9 33.23
6 11 30.82
7 13 -17.04
8 15 -54.87
9 18 14.95
10 19 -33.20
11 21 78.52
12 23 0.00

(Numerical Example 3)
Unit mm
Surface data surface number rd nd νd Effective diameter
1 * 31.796 1.79 1.80 400 46.6 29.42
2 * 9.830 8.30 22.81
3 -35.096 1.30 1.80400 46.6 22.81
4 -64.769 0.16 23.24
5 32.516 3.00 2.01960 21.5 23.46
6 71.814 (variable) 22.85
7 * 31.170 2.80 1.86400 40.6 16.62
8 * 85.586 0.05 16.19
9 11.242 6.00 1.59240 68.3 16.74
10 135.733 1.20 15.14
11 * 24.226 1.05 2.01960 21.5 13.13
12 * 10.498 4.41 11.49
13 (Aperture) ∞ 1.59 11.46
14 * 34.437 2.80 1.80400 46.6 11.43
15 270.327 (variable) 11.06
16 41.118 3.20 1.49700 81.5 20.86
17 681.715 (variable) 20.95
18 ∞ 2.73 1.51633 64.1 36.07
19 ∞ 1.21 36.07
Image plane ∞

Aspheric data 1st surface
K = 0.00000e + 000 A 4 = -1.28658e-004 A 6 = 1.32872e-006 A 8 = -1.01281e-008
A10 = 4.75459e-011 A12 = -1.23253e-013 A14 = 1.34569e-016

Second side
K = -7.62406e-001 A 4 = -1.13721e-004 A 6 = 2.10161e-006 A 8 = -1.36238e-008
A10 = 4.31973e-011 A12 = 1.65975e-014 A14 = -3.15666e-016
A 3 = 3.47969e-006 A 5 = -5.89859e-006

7th page
K = 0.00000e + 000 A 4 = 3.53516e-005 A 6 = 1.38152e-007 A 8 = 1.25903e-009

8th page
K = 0.00000e + 000 A 4 = 5.83141e-005 A 6 = 1.68920e-007 A 8 = 2.17542e-009

11th page
K = 0.00000e + 000 A 4 = 5.57155e-005 A 6 = 1.50883e-007 A 8 = -8.95593e-009

12th page
K = 1.06567e + 000 A 4 = 5.28623e-006 A 6 = 2.02951e-007 A 8 = -1.37196e-008
A 3 = -2.27696e-005

14th page
K = 0.00000e + 000 A 4 = -8.18854e-006 A 6 = -3.07774e-007 A 8 = 1.80660e-008
A10 = -1.75598e-010

Various data Zoom ratio 2.72

Focal length 12.36 23.10 33.60 17.58 28.53
F number 2.06 2.87 3.60 2.46 3.26
Angle of View 41.01 24.95 17.74 31.45 20.65
Image height 10.75 10.75 10.75 10.75 10.75
Total lens length 82.03 77.35 82.29 77.66 79.22
BF 1.21 1.21 1.21 1.21 1.21

d 6 26.35 9.76 2.79 16.02 5.67
d15 8.61 24.19 34.07 17.12 29.85
d17 5.47 1.80 3.83 2.92 2.10

Entrance pupil position 17.29 16.01 15.29 16.55 15.60
Exit pupil position -22.96 -45.32 -72.12 -33.14 -58.71
Front principal point 23.33 27.64 33.49 25.14 30.55
Rear principal point position -11.15 -21.89 -32.39 -16.37 -27.32

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -23.07 14.55 0.02 -12.29
2 7 23.04 19.90 -0.93 -16.38
3 16 87.90 3.20 -0.14 -2.27


Single lens Data lens Start surface Focal length
1 1 -18.37
2 3 -97.18
3 5 56.12
4 7 55.42
5 9 20.33
6 11 -18.90
7 14 48.83
8 16 87.90
9 18 0.00

(Numerical example 4)
Unit mm
Surface data surface number rd nd νd Effective diameter
1 * 411.705 1.79 1.80400 46.6 27.48
2 * 16.998 7.00 22.59
3 -54.572 1.30 1.80400 46.6 22.09
4 637.541 0.16 22.17
5 42.173 2.44 2.01960 21.5 22.31
6 170.229 (variable) 22.01
7 94.243 2.50 1.65 160 58.5 23.70
8 2462.574 0.04 23.97
9 21.635 4.50 1.69680 55.5 25.02
10 78.686 0.16 24.40
11 * 14.822 5.50 1.72916 54.7 22.48
12 61.287 0.90 20.81
13 54.610 0.81 1.80518 25.4 19.33
14 10.698 5.00 15.89
15 (Aperture) ∞ 1.10 15.57
16 * 27.248 4.00 1.80 400 46.6 15.11
17 -23.475 0.80 1.80610 33.3 14.46
18 10682.757 (variable) 13.77
19 28.314 3.00 1.48749 70.2 20.99
20 70.327 (variable) 20.93
21 ∞ 2.73 1.51633 64.1 36.07
22 ∞ 1.51 36.07
Image plane ∞

Aspheric data 1st surface
K = 0.00000e + 000 A 4 = -7.02211e-006 A 6 = 1.24864e-007 A 8 = -1.74666e-009
A10 = 9.65150e-012 A12 = -1.87220e-014 A14 = 8.54640e-018

Second side
K = -9.42934e-001 A 4 = 5.71875e-006 A 6 = 1.57767e-007 A 8 = 8.28848e-010
A10 = -4.39092e-011 A12 = 3.35921e-013 A14 = -5.91689e-016

11th page
K = -4.77208e-001 A 4 = 1.40167e-006 A 6 = 1.12170e-007 A 8 = -1.62654e-009
A10 = 1.68412e-011 A12 = -9.03498e-014 A14 = 1.88274e-016

16th page
K = 1.19088e + 000 A 4 = -1.96436e-005 A 6 = -8.60556e-008 A 8 = 1.34813e-009
A10 = -6.18519e-012

Various data Zoom ratio 2.37

Focal length 14.20 23.85 33.60 18.97 28.74
F number 1.40 2.05 2.71 1.72 2.39
Angle of view 37.13 24.27 17.74 29.53 20.51
Image height 10.75 10.75 10.75 10.75 10.75
Total lens length 79.63 76.32 80.53 76.37 77.94
BF 1.51 1.51 1.51 1.51 1.51

d 6 20.41 6.83 0.79 12.02 3.32
d18 10.06 21.80 32.16 16.10 27.15
d20 3.91 2.43 2.34 3.00 2.21

Entrance pupil position 18.17 17.08 16.46 17.54 16.74
Exit pupil position -23.44 -40.13 -61.92 -31.18 -50.35
Front principal point position 24.29 27.27 32.27 25.50 29.55
Rear principal point position -12.69 -22.33 -32.09 -17.46 -27.23

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -24.02 12.69 0.43 -9.91
2 7 22.91 25.32 3.03 -17.57
3 19 95.00 3.00 -1.33 -3.30


Single lens Data lens Start surface Focal length
1 1 -22.10
2 3 -62.47
3 5 54.46
4 7 150.33
5 9 41.48
6 11 25.54
7 13 -16.66
8 16 16.26
9 17 -29.06
10 19 95.00
11 21 0.00

(Numerical example 5)
Unit mm
Surface data surface number rd nd νd Effective diameter
1 * 31.621 1.79 1.80 400 46.6 28.34
2 * 9.861 8.30 22.12
3 -33.760 1.30 1.80400 46.6 22.04
4 -68.932 0.16 22.43
5 32.791 3.00 2.01960 21.5 22.59
6 75.983 (variable) 21.98
7 * 35.410 2.80 1.86400 40.6 16.80
8 * 84.338 0.05 16.43
9 11.609 6.00 1.59240 68.3 17.26
10 536.924 1.20 15.93
11 * 24.966 1.05 2.01960 21.5 13.69
12 * 11.428 4.41 12.12
13 (Aperture) ∞ 1.59 12.02
14 * 31.582 2.80 1.80400 46.6 11.92
15 129.053 (variable) 11.49
16 92.742 3.20 1.49700 81.5 20.16
17 -127.139 (variable) 20.47
18 ∞ 2.73 1.51633 64.1 36.07
19 ∞ 1.08 36.07
Image plane ∞

Aspheric data 1st surface
K = 0.00000e + 000 A 4 = -1.17723e-004 A 6 = 1.30724e-006 A 8 = -1.03830e-008
A10 = 4.81826e-011 A12 = -1.21430e-013 A14 = 1.28713e-016

Second side
K = -7.17671e-001 A 4 = -1.03685e-004 A 6 = 2.18514e-006 A 8 = -1.44776e-008
A10 = 3.82105e-011 A12 = 3.09270e-014 A14 = -2.97724e-016
A 3 = 3.47969e-006 A 5 = -5.89859e-006

7th page
K = 2.56441e + 000 A 4 = 3.10775e-005 A 6 = 6.72064e-008 A 8 = 1.09326e-009
A10 = -2.67539e-011 A12 = 7.60732e-014 A14 = -7.66065e-016

8th page
K = 6.32387e + 000 A 4 = 6.69255e-005 A 6 = 1.23190e-007 A 8 = 1.30193e-009
A10 = -2.32117e-011 A12 = -1.14906e-013 A14 = -4.46849e-016

11th page
K = 2.18150e + 000 A 4 = 5.84737e-005 A 6 = 3.59674e-007 A 8 = -1.38457e-008
A10 = -1.79369e-011 A12 = -1.50742e-012 A14 = -1.11107e-014

12th page
K = 1.26842e + 000 A 4 = 6.25151e-006 A 6 = 4.68781e-007 A 8 = -1.66033e-008
A10 = 5.49280e-010 A12 = -3.69030e-012 A14 = -4.12629e-013
A 3 = -2.27696e-005

14th page
K = -3.20384e + 000 A 4 = -1.46844e-005 A 6 = -2.49416e-007 A 8 = 1.75294e-008
A10 = -1.90957e-010

Various data Zoom ratio 2.72

Focal length 12.36 23.09 33.60 17.61 28.49
F number 2.06 2.86 3.60 2.46 3.25
Angle of View 41.01 24.96 17.74 31.40 20.67
Image height 10.75 10.75 10.75 10.75 10.75
Total lens length 82.93 78.13 83.23 78.37 80.09
BF 1.08 1.08 1.08 1.08 1.08

d 6 26.35 9.65 2.84 15.84 5.65
d15 8.61 24.19 34.07 17.12 29.85
d17 6.50 2.83 4.86 3.95 3.13

Entrance pupil position 16.98 15.65 14.91 16.21 15.23
Exit pupil position -23.88 -44.07 -66.70 -33.29 -55.49
Front principal point position 23.22 26.93 31.85 24.80 29.37
Rear principal point position -11.28 -22.01 -32.52 -16.53 -27.41

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -22.42 14.55 0.25 -11.97
2 7 22.96 19.90 -0.22 -15.70
3 16 108.42 3.20 0.91 -1.24


Single lens Data lens Start surface Focal length
1 1 -18.50
2 3 -83.67
3 5 54.66
4 7 68.82
5 9 19.95
6 11 -21.51
7 14 51.35
8 16 108.42
9 18 0.00

  Next, an embodiment of a digital still camera (image pickup apparatus) using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG. In FIG. 11, reference numeral 20 denotes a camera body, and 21 denotes a photographing optical system constituted by the zoom lens of the present invention. Reference numeral 22 denotes a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor that receives a subject image formed by the photographing optical system 21 and is built in the camera body. A memory 23 records information corresponding to the subject image photoelectrically converted by the image sensor 22. Reference numeral 24 is a finder for observing a subject image formed on the solid-state image sensor 22, which includes a liquid crystal display panel or the like. Thus, by applying the zoom lens of the present invention to an image pickup apparatus such as a digital still camera, a small image pickup apparatus having high optical performance is realized.

L1 First lens group L2 Second lens group L3 Third lens group SP Aperture stop

Claims (7)

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 including an aperture stop, and a third lens group having a positive refractive power, which are adjacent to each other during zooming A zoom lens in which the third lens group moves during focusing when the group interval changes, and the second lens group includes two or more positive lenses and one or more negative lenses in order from the object side to the image side. The third lens unit has a focal length of f3, the focal lengths of the entire system at the wide-angle end and the telephoto end are respectively fw and ft, and the F-numbers at the wide-angle end and the telephoto end are respectively Fnow and Fnot, and the final lens at the telephoto end. BFt is the air-converted distance from the surface to the image surface, and the focal lengths of the positive lens disposed closest to the object side of the second lens group and the positive lens disposed adjacent to the image side of the positive lens are respectively f21 , F22 ,
0.20 <Fnow * fw / f3 <0.43
0.4 <BFt * Fnot / ft <0.9
2.0 <f21 / f22 <4.0
A zoom lens satisfying the following conditional expression: The radius of curvature of the lens surface on the image side of the positive lens disposed closest to the object side in the second lens group is R21b, and the lens surface on the object side of the positive lens disposed at a position adjacent to the image side of the positive lens. When the curvature radius is R22a,
−2.0 <(R22a + R21b) / (R22a−R21b) <0.0
The zoom lens according to claim 1, wherein the following condition is satisfied. When the focal length of the first lens group is f1,
-1.6 <Fnow * fw / f1 <-0.5
The zoom lens according to claim 1 or 2, characterized by satisfying the following condition. The zoom lens according to any one of claims 1 to 3 , wherein the third lens group includes one positive lens or a cemented lens in which a positive lens and a negative lens are cemented. The aperture stop is disposed between the lenses of the second lens group, and the combined refractive power of the lenses disposed on the image side of the aperture stop in the second lens group is positive. 5. The zoom lens according to any one of 1 to 4 . During zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group is reduced, and the distance between the second lens group and the third lens group is increased. 2, the third lens group is moved, the third lens group, according to any one of claims 1 to 5, characterized in that moves toward the object side during focusing from infinity to a close object Zoom lens. A zoom lens according to any one of claims 1 to 6, the imaging apparatus characterized by having a photoelectric conversion element for receiving an image formed by the zoom lens.