JP2012088602A - Zoom lens and imaging apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens which effectively reduces flare light, has a wide angle of view and is compact as a whole.SOLUTION: In the zoom lens which has a first lens group L1 having positive refractive power, a second lens group L2 having negative refractive power, a third lens group L3 having positive refractive power, and a fourth lens group L4 having positive refractive power in order from an object side to an image side, and in which when the zoom lens zooms, the first group is immovable, and the second lens group, the third lens group and the fourth lens group move, a flare-cut diaphragm FC having a fixed aperture diameter is provided between the second lens group and the third lens group, and the flare-cut diaphragm moves when the zoom lens zooms.

Description

  The present invention relates to a zoom lens and an image pickup apparatus having the same, and is particularly suitable for a video camera, a silver salt photography camera, a digital camera, a TV camera, a surveillance camera, and the like.

  In recent years, a photographing optical system used in an image pickup apparatus such as a video camera or a digital still camera using a solid-state image pickup element is required to be a zoom lens having a wide angle of view and a high zoom ratio. As a zoom lens that meets these requirements, a four-group zoom lens that includes first to fourth lens units having positive, negative, positive, and positive refractive powers in order from the object side to the image side is known. Among them, the second lens group and the third lens group are moved to perform zooming, the fourth lens group is moved to correct image plane variation accompanying zooming, and the fourth lens group is focused. A rear focus type four-group zoom lens is known (Patent Documents 1 and 2).

JP 2006-47771 A JP 2009-128607 A

  In recent years, a photographing lens system (photographing optical system) used in an imaging apparatus is strongly desired to have a wide angle of view and a high zoom ratio (high magnification). In addition, as the number of pixels of the image sensor increases, it is desired to have higher optical performance. In order to obtain high optical performance, it is important to prevent light beams other than the effective angle of view, light beams reflected by the lens surface, and the like from entering the imaging surface and becoming flare light.

In general, a zoom lens having a wide angle of view and a high zoom ratio often generates flare light. For this reason, in order to cut flare light, a flare cut stop with a fixed aperture diameter is arranged in the optical path.
In the 4-group zoom lens composed of lens groups having positive, negative, positive, and positive refractive power in Patent Document 1, a flare-cut stop having a fixed aperture diameter is disposed on the object side of the aperture stop. However, there is no description of what kind of flare is to be cut by the flare-cut stop, and it is not always sufficient in terms of the wide angle of view at the wide angle end. In the four-group zoom lens disclosed in Patent Document 2, a flare-cut stop is disposed on the subject side and the image side of the second lens group, or inside the third lens group. By moving it together with the lens group, the entire system is reduced in size while achieving a wide angle of view. However, since the first lens unit moves during zooming, the total lens length tends to be longer at the telephoto end.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a zoom lens having a wide angle of view and a compact overall size and an image pickup apparatus having the same while effectively reducing flare light.

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 positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive lens having a positive refractive power. In the zoom lens configured by the fourth lens group, the first lens group does not move during zooming, and the second lens group, the third lens group, and the fourth lens group move.
A flare-cut stop having a fixed aperture diameter is provided between the second lens group and the third lens group, and the flare-cut stop moves during zooming.

  According to the present invention, it is possible to obtain a zoom lens having a wide angle of view and a compact size while effectively reducing flare light.

Lens cross-sectional view at the wide-angle end of the zoom lens of Example 1 Various aberration diagrams of the zoom lens of Example 1 Lens sectional view at the wide-angle end of the zoom lens according to Embodiment 2 Various aberration diagrams of the zoom lens of Example 2 Lens sectional view at the wide-angle end of the zoom lens according to Embodiment 3 Various aberration diagrams of the zoom lens of Example 3 Lens sectional view at the wide-angle end of the zoom lens according to Embodiment 4 Various aberration diagrams of the zoom lens of Example 4 Lens sectional view at the wide-angle end of the zoom lens according to Embodiment 5 Various aberration diagrams of the zoom lens of Example 5 Lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 6 Various aberration diagrams of the zoom lens of Example 6 Schematic diagram of main parts of an imaging apparatus of the present invention

  Embodiments of a zoom lens of the present invention and an image pickup apparatus having the same will be described below with reference to the 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 positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive lens having a positive refractive power. A fourth lens group is included. During zooming, the first lens group does not move, and the second lens group, the third lens group, and the fourth lens group move on the optical axis. A flare-cut stop having a fixed aperture diameter is provided between the second lens group and the third lens group, and the flare-cut stop moves during zooming.

  In the zoom lens of the present invention, a lens group having refractive power may be disposed on at least one of the object side of the first lens group or the image side of the fourth lens group. FIG. 1 is a lens cross-sectional view at the wide-angle end of the zoom lens according to the first exemplary embodiment of the present invention. 2A, 2B, and 2C are aberration diagrams at the wide-angle end (short focal length end), the intermediate zoom position, and the telephoto end (long focal length end) of the zoom lens according to the first exemplary embodiment of the present invention. It is. The zoom lens of Numerical Example 1 has a zoom ratio of 9.71 and a shooting field angle of 70.82 ° at the wide-angle end.

  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. FIGS. 4A, 4B, and 4C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to the second embodiment of the present invention. The zoom lens of Numerical Example 2 has a zoom ratio of 9.71 and a shooting field angle of 75.28 ° at the wide-angle end. 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, 6B, and 6C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 3 of the present invention. The zoom lens according to Numerical Example 3 has a zoom ratio of 13.68 and a shooting field angle of 70.78 ° at the wide-angle end.

  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. FIGS. 8A, 8B, and 8C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to the fourth exemplary embodiment of the present invention. The zoom lens according to Numerical Example 4 has a zoom ratio of 9.70 and a shooting field angle of 76.56 ° at the wide-angle end. 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, 10B, and 10C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Example 5 of the present invention. The zoom lens according to Numerical Example 5 has a zoom ratio of 11.71 and a shooting field angle of 75.3 ° at the wide-angle end.

  FIG. 11 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Example 6 of the present invention. FIGS. 12A, 12B, and 12C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to the sixth exemplary embodiment of the present invention. The zoom lens according to Numerical Example 6 has a zoom ratio of 9.71 and a shooting field angle of 75.26 ° at the wide-angle end. FIG. 13 is a schematic diagram of a main part of a video camera (imaging device) equipped with the zoom lens of the present invention.

  The zoom lenses of Numerical Examples 1 to 6 are photographic lens systems used in the imaging apparatus. In the lens cross-sectional view, the left side is the subject side (object side) and the right side is the image side. In the lens sectional view, L1 is a first lens group having a positive refractive power, L2 is a second lens group having a negative refractive power, L3 is a third lens group having a positive refractive power, and L4 is a fourth lens having a positive refractive power. It is a lens group. SP is an aperture stop (stop), which is located on the object side of the third lens unit L3, and is fixed during zooming. The aperture stop SP may be moved during zooming. FC is a flare-cut stop having a fixed (invariable) aperture diameter, and is located between the second lens unit L2 and the third lens unit L3, and moves independently of the other lens units during zooming.

  G is an optical block corresponding to an optical filter, a face plate, or the like. IP is an image plane. When used as a photographing optical system for a digital still camera or a video camera, the imaging plane of a solid-state imaging device such as a CCD sensor or a CMOS sensor corresponds to a film plane when a camera for a silver salt film is used. To do. In the aberration diagrams, spherical aberration is shown for d-line and g-line. In the astigmatism diagram, ΔM and ΔS are a meridional image surface and a sagittal image surface. Lateral chromatic aberration is represented by the g-line. Fno is an F number. ω is a half angle of view. In the following embodiments, the wide-angle end and the telephoto end refer to zoom positions when the variable power lens unit (second lens unit) is positioned at both ends of the range in which the mechanism can move on the optical axis.

  In each embodiment, as shown by an arrow during zooming from the wide-angle end to the telephoto end, the second lens unit L2 moves toward the image side, and the third lens unit L3 moves non-linearly toward the subject side. Is going. At this time, the third lens unit L3 moves in a curve so as to have an inflection point at a zoom position closer to the telephoto side in order to correct a change in curvature of field due to zooming. Further, by moving the fourth lens unit L4 to the object side, the image plane variation due to zooming is corrected. In addition, a rear focus type that performs focusing by moving the fourth lens unit L4 on the optical axis is employed. A solid curve 4a and a dotted curve 4b relating to the fourth lens unit L4 are movement trajectories for correcting image plane fluctuations accompanying zooming when focusing on an object at infinity and an object at close distance, respectively.

  Further, when focusing from an object at infinity to an object at a short distance at the telephoto end, the fourth lens unit L4 is moved forward as indicated by an arrow 4c. The first lens unit L1 is fixed in the optical axis direction for focusing, but may be moved as necessary for correcting aberrations. Further, at the time of photographing, the whole or a part of the third lens unit L3 is moved so as to have a component perpendicular to the optical axis, and the photographed image is moved in a direction perpendicular to the optical axis. . This corrects blurring of the captured image when the zoom lens vibrates.

  The zoom lens of each embodiment achieves a wide angle of view and a compact system. Here, in order to achieve a wide angle of view, a negative lead type in which the first lens unit has a negative power is advantageous. However, the negative lead type has a large drop in F number when the zoom ratio (magnification) is increased. That is, the F number increases. In particular, the drop in the F number becomes larger at the telephoto end. Therefore, it is difficult to achieve a high zoom ratio. On the other hand, in order from the object side to the image side, a four-unit zoom lens including lens units having positive, negative, positive, and positive refractive powers has a small F-number drop when the zoom ratio is increased.

  In the zoom lens of each embodiment, the second and fourth lens groups are moved during zooming, and the third lens group is also movable so that the entrance pupil on the wide angle side is closer to the front lens and the effective diameter of the front lens is increased. Widening the angle of view while suppressing it. Specifically, the third lens unit L3 is moved to the subject side at a zoom position closer to the wide angle side that determines the front lens effective diameter than the wide angle end. Further, by providing the third lens unit L3 with variable magnification, the variable magnification distribution of the second lens unit L2 is reduced, and the space from the front lens (first lens unit L1) to the stop SP is reduced, and the front lens The effective diameter of the ball is reduced. In addition, by adopting a flare-cut stop FC with a fixed (invariable) aperture diameter and moving independently of other lens units during zooming, unnecessary light is cut off especially at the zoom position on the wide-angle side, making the entire system compact. To improve performance and performance.

  At the zoom position on the wide-angle side, the lower ray of the intermediate image height passes outside the axial light beam between the second and third lens groups, which causes coma flare. For this reason, the underline flare is efficiently cut by disposing the flare cut stop FC on the subject side having a small axial beam diameter at the zoom position on the wide angle side. However, if the flare-cut stop FC is disposed too close to the subject at the zoom position on the wide-angle side, it is preferable for cutting unnecessary light, but the amount of light on the screen periphery decreases. For this reason, it is important to appropriately set the position of the flare cut stop FC in the optical axis direction. Specifically, if the axial light beam is cut by the flare-cut stop FC, the F-number falls, so the lower light beam of the intermediate image height and the lower light beam of the axial light beam intersect the flare-cut stop FC. Arranging in the vicinity may also secure the amount of light around the screen.

  In the zoom lens of each embodiment, in order to achieve a wide angle of view, it is preferable to shorten the focal length of the entire system. In order to shorten the focal length of the entire system, it is necessary to increase the power of the second lens group. At this time, a large amount of field curvature and coma with an intermediate image height occur at the zoom position on the wide angle side. In each embodiment, unnecessary light is cut by disposing a flare cut stop FC having a fixed (invariable) aperture diameter between the second lens unit L2 and the third lens unit L3. By moving the third lens unit L3 during zooming, a zoom lens having a wide angle of view is obtained while reducing the effective diameter of the front lens. In each embodiment, by configuring as described above, a compact zoom lens having a wide angle of view, a high zoom ratio, a small amount of flare light over the entire zoom range, and high optical performance can be obtained. In each embodiment, it is more preferable to satisfy one or more of the following conditions.

  The lateral magnifications at the wide-angle end and the telephoto end of the second lens unit L2 are β2w and β2t, respectively. The lateral magnifications at the wide-angle end and the telephoto end of the third lens unit L3 are β3w and β3t, respectively. Let fw be the focal length of the entire system at the wide-angle end. The focal lengths of the first lens unit L1 and the second lens unit L2 are f2. The movement amounts of the third lens unit L3 and the flare cut stop FC during zooming from the wide-angle end to the telephoto end are f3st and Sst, respectively.

Here, the amount of movement f3st of the third lens unit L3 accompanying zooming from the wide-angle end to the telephoto end is a difference in position of the third lens unit L3 with respect to the image plane at the wide-angle end and the telephoto end. However, the sign when the third lens unit L3 is located on the object side is negative at the telephoto end compared with the wide-angle end, and the sign when it is located on the image side is positive. The movement amount Sst of the flare cut stop FC is the same as that of the third lens unit L3. At this time,
2.0 <β2t / β2w <6.5 (1)
3.6 <β3t / β3w <10.0 (2)
-2.2 <f2 / fw <-1.8 (3)
11.0 <f1 / fw <14.0 (4)
1.2 <Sst / f3st <2.0 (5)
It is preferable to satisfy one or more of the following conditional expressions.

  Conditional expression (1) relates to the variable magnification sharing of the second lens unit L2. If the lower limit value of conditional expression (1) is not reached, the variable power sharing of the second lens unit L2 decreases. This facilitates correction of field curvature and lateral chromatic aberration on the wide angle side. However, in order to achieve a high zoom ratio, the variable magnification share of the third lens unit L3 increases, the amount of movement of the third lens unit L3 increases, and the overall lens length increases. On the other hand, if the upper limit value is exceeded, the variable magnification share of the second lens unit L2 increases, so the amount of movement of the second lens unit L2 during zooming increases, and the effective diameter of the front lens increases. In addition, since the power of the second lens unit L2 is increased, the variation in field curvature accompanying zooming is increased.

  Conditional expression (2) relates to variable magnification sharing of the third lens unit L3. If the lower limit value of the conditional expression (2) is not reached, the variable magnification share of the third lens unit L3 decreases, so that the amount of movement of the second lens unit L2 must be increased in order to achieve a high zoom ratio. As a result, the effective diameter of the front lens is increased. On the other hand, if the upper limit value of conditional expression (2) is exceeded, the variable magnification share of the third lens unit L3 increases, so that the distance between the stop SP and the third lens unit L3 is widened, and the overline flare is suppressed particularly at the wide-angle end. It becomes difficult. Further, it is necessary to secure a large amount of movement during zooming of the third lens unit L3. As a result, the total lens length increases, which is not good.

  Conditional expression (3) relates to the power of the second lens unit L2 and is intended to satisfactorily correct field curvature mainly in the entire zoom range. If the lower limit of conditional expression (3) is not reached, the power of the second lens unit L2 is weakened, so that the variation in field curvature due to zooming becomes small, which is preferable in terms of optical performance. However, since the amount of movement of the second lens unit L2 during zooming increases, the overall length of the lens increases. On the other hand, when the value exceeds the upper limit value, the power of the second lens unit L2 is increased, and the amount of movement of the second lens unit L2 during zooming is reduced, so the front lens effective diameter is reduced. However, it is not preferable because the fluctuation of the field curvature increases during zooming.

  Conditional expression (4) relates to the power distribution of the first lens unit L1 and is intended to satisfactorily correct spherical aberration and axial chromatic aberration mainly at the telephoto end. If the lower limit of conditional expression (4) is not reached, the power of the first lens unit L1 will increase, and it will be difficult to correct spherical aberration at the telephoto end. In addition, it becomes difficult to correct axial chromatic aberration at the telephoto end. On the other hand, if the value exceeds the upper limit, the power of the first lens unit L1 is weakened, and therefore the amount of movement of the second lens unit L2 during zooming is increased, and the effective diameter of the front lens is increased.

  Conditional expression (5) relates to the ratio of the amount of movement of the third lens unit L3 and the flare cut stop FC during zooming. If the lower limit value of conditional expression (5) is not reached, the amount of movement of the flare cut stop FC will decrease, making it difficult to sufficiently cut the underline flare at the zoom position on the wide-angle side, and the optical performance will deteriorate. Further, the movement amount of the third lens unit L3 becomes too large, the entire lens length becomes large, and the optical performance deteriorates due to the overline flare at the zoom position on the wide angle side. On the other hand, if the value exceeds the upper limit value, the amount of movement of the flare cut stop FC increases, so it becomes easy to reduce the effective diameter of the front lens and cut the underline flare, but it is difficult to secure the amount of light around the screen.

  The flare-cut stop FC with a fixed aperture is arranged on the subject side at the wide-angle zoom position, and is moved monotonically along the convex locus from the wide-angle end to the telephoto end on the image side or subject side (object side). Is good. The flare-cut stop FC is effective for cutting unnecessary light having an intermediate image height on the wide-angle side that causes deterioration of optical performance. However, the optical path difference between the intermediate image height and the peripheral image height disappears as zooming is performed. For this reason, it is preferable to move the flare cut stop FC to the image side simultaneously with zooming from the wide-angle end to the telephoto end in order to secure the amount of light around the screen.

  More preferably, the flare cut stop FC is moved independently of the second lens unit L2 and the third lens unit L3 during zooming. The second lens unit L2 and the third lens unit L3 are moved to the image side and the subject side, respectively, so as to contribute to multiplication during zooming. For this reason, the flare cut stop FC is preferably moved to the image side independently of the second lens unit L2 in order to secure the amount of light around the screen.

  In each embodiment, the front lens effective diameter is reduced by configuring each lens group as described above. The entire lens system is miniaturized, and high optical performance is obtained over the entire zoom range and the entire object distance despite the simple lens configuration.

  In each numerical example, it is more preferable to set the numerical ranges of the conditional expressions (1) to (5) as follows in terms of aberration correction.

2.2 <β2t / β2w <6.4 (1a)
3.7 <β3t / β3w <9.8 (2a)
−2.15 <f2 / fw <−1.85 (3a)
11.1 <f1 / fw <13.8 (4a)
1.25 <Sst / f3st <1.95 (5a)
More preferably, the numerical ranges of the conditional expressions (1a) to (5a) are set as follows.

2.4 <β2t / β2w <6.3 (1b)
3.8 <β3t / β3w <9.6 (2b)
-2.1 <f2 / fw <-1.9 (3b)
11.2 <f1 / fw <13.6 (4b)
1.3 <Sst / f3st <1.9 (5b)
In each numerical example, by configuring each lens group as described above, the front lens diameter is reduced, and the entire lens system is reduced in size. High optical performance is obtained over the entire object distance.

  Note that the zoom lens of each embodiment may correct distortion among various aberrations by electrical image processing. In particular, a photographing system such as a digital camera or a video camera preferably has a small distortion. For this reason, if the wide-angle side is set to an imaging range smaller than the maximum imaging range (effective image circle diameter) and distortion is corrected, further reduction of the effective diameter of the front lens becomes easy.

  Next, the lens configuration of each lens group will be described. Hereinafter, it is assumed that the lenses of each lens group are arranged in order from the object side to the image side. The first lens unit L1 includes a cemented lens in which a negative lens and a positive lens are cemented, and a meniscus positive lens having a convex object side surface. In the zoom lens of each embodiment, the positive refractive power of the first lens unit L1 is increased in order to reduce the size of the entire system. At this time, various aberrations that occur in the first lens unit L1, particularly spherical aberration, occur on the telephoto side. Therefore, the positive refractive power of the first lens unit L1 is shared by the cemented lens and the positive lens to reduce the occurrence of these aberrations.

  In the second lens unit L2, the absolute value of the refractive power is stronger on the image side than on the object side, the image side lens surface is a concave negative lens, the image side lens surface is a concave negative lens, and the object side surface. Is composed of a concave negative lens and a biconvex positive lens. In the zoom lens of each embodiment, the negative refractive power of the second lens unit L2 is increased in order to reduce the effective diameter of the first lens unit L1 while obtaining a wide angle of view at the wide angle end. At this time, various aberrations that occur in the second lens unit L2, particularly distortion and field curvature occur frequently on the wide angle side. In each embodiment, the negative refractive power of the second lens unit L2 is shared by three negative lenses to reduce the occurrence of field curvature. With such a lens configuration, the effective diameter of the front lens is reduced and high optical performance is obtained while widening the angle of view.

  By using a high dispersion material having an Abbe number smaller than 20 as the material of the positive lens, the refractive power of the lens necessary for achromatization is made as small as possible. As a result, the entire system is reduced in size while suppressing the occurrence of curvature of field and lateral chromatic aberration. The third lens unit L3 includes a positive lens having a convex lens surface on the object side, a negative lens having a concave lens surface on the image side, and a positive lens having a convex lens surface on the object side. In the zoom lens of each embodiment, the positive refractive power of the third lens unit L3 is strengthened in order to shorten the entire lens length at the wide-angle end and shorten the movement amount during zooming. At this time, various aberrations generated in the third lens unit L3, particularly axial chromatic aberration and coma aberration, are often generated. Therefore, the third lens unit L3 shares power with two positive lenses and one negative lens to reduce achromaticity and coma.

  The fourth lens unit L4 includes a cemented lens in which a positive lens and a negative lens are cemented. In each embodiment, the fourth lens unit L4 is configured with a small number of lenses to reduce the thickness and weight of the entire system.

  The numerical examples 1 to 6 corresponding to the first to sixth examples are shown below. In each numerical example, i indicates the order of the surfaces from the object side, ri is the i-th (i-th surface) radius of curvature, di is the distance from the (i + 1) -th surface, and ndi and νdi are d-lines, respectively. Represents the refractive index and Abbe number of the material of the i-th optical member with reference to. In Numerical Examples 1 to 6, the two surfaces closest to the image are planes corresponding to the optical block G. In the aspherical shape, the displacement in the optical axis direction at the position of the height H from the optical axis is defined as X with reference to the surface vertex. The traveling direction of light is positive, R is a paraxial radius of curvature, k is a conic constant, and A4, A6, and A8 are aspherical coefficients. At this time,

It is expressed by the following formula. * Means a surface having an aspherical shape. “E-x” means 10 ^−x . BF is a back focus. In each numerical example, the stop SP and the flare cut stop FC are shown as one group. Two surfaces (planes) closest to the image side are also shown as one group. Therefore, as a whole, it is shown as consisting of seven groups. Table 1 shows the relationship between the above-described conditional expressions and numerical values in the numerical examples.

Numerical example 1
Surface data surface number rd nd νd
1 47.935 1.50 1.84666 23.9
2 26.133 4.80 1.69680 55.5
3 151.789 0.18
4 30.365 2.47 1.77250 49.6
5 77.873 (variable)
6 102.431 0.70 1.88300 40.8
7 7.254 3.04
8 -77.650 0.60 1.80610 33.3
9 21.898 1.50
10 -18.408 0.60 1.80 400 46.6
11 -126.472 0.04
12 25.735 1.82 1.92286 18.9
13 -39.752 (variable)
14 flare cut aperture ∞ (variable)
15 (Aperture) ∞ (Variable)
16 * 9.840 3.17 1.58313 59.4
17 -94.650 2.63
18 25.958 0.60 1.80518 25.4
19 9.134 0.82
20 * 17.145 1.80 1.58313 59.4
21 -179.309 (variable)
22 16.142 3.33 1.51633 64.1
23 -14.756 1.00 1.84666 23.9
24 -27.062 (variable)
25 ∞ 2.38 1.54400 60.0
26 ∞ (variable)
Image plane ∞

Aspheric data 16th surface
K = -4.78345e-001 A 4 = -4.44470e-005 A 6 = -6.51597e-008 A 8 = -3.12161e-009

20th page
K = 4.10582e + 000 A 4 = -1.45777e-004 A 6 = -1.26609e-006

Various data Zoom ratio 9.71
Wide angle Medium Telephoto focal length 3.80 18.03 36.86
F number 1.85 2.99 3.40
Half angle of view 35.41 9.44 4.65
Total lens length 79.35 79.35 79.35
BF 9.14 14.61 16.62

d 5 0.92 18.06 24.17
d13 13.08 4.03 0.80
d14 12.47 4.38 1.50
d15 9.65 2.40 2.24
d21 3.50 5.28 3.43
d24 5.93 11.40 13.40
d26 1.68 1.68 1.68

Zoom lens group data group Start surface Focal length
1 1 43.80
2 6 -7.59
3 14 ∞
4 15 ∞
5 16 19.59
6 22 24.95
7 25 ∞

Numerical example 2
Surface data surface number rd nd νd
1 42.310 1.70 1.84666 23.9
2 26.392 5.85 1.65 160 58.5
3 114.346 0.18
4 29.827 2.84 1.75 500 52.3
5 68.096 (variable)
6 102.562 0.70 1.88300 40.8
7 7.242 2.88
8 -316.537 0.60 1.80610 33.3
9 21.171 1.59
10 -17.306 0.60 1.83481 42.7
11 1268.231 0.19
12 27.172 1.82 1.92286 18.9
13 -36.944 (variable)
14 flare cut aperture ∞ (variable)
15 (Aperture) ∞ (Variable)
16 * 10.425 3.03 1.58313 59.4
17 -72.303 2.50
18 29.525 0.60 1.80518 25.4
19 9.811 0.69
20 * 16.760 1.83 1.58313 59.4
21 -118.067 (variable)
22 18.141 3.36 1.51823 58.9
23 -12.620 1.00 1.84666 23.9
24 -21.570 (variable)
25 ∞ 2.38 1.54400 60.0
26 ∞ (variable)
Image plane ∞

Aspheric data 16th surface
K = -5.48220e-001 A 4 = -3.59009e-005 A 6 = -3.47083e-008 A 8 = -3.73321e-009

20th page
K = 3.81603e + 000 A 4 = -1.52466e-004 A 6 = -9.89056e-007

Various data Zoom ratio 9.71
Wide angle Medium telephoto focal length 3.50 16.58 34.00
F number 1.85 2.99 3.40
Half angle of view 37.64 10.26 5.04
Total lens length 82.17 82.17 82.17
BF 8.76 14.54 17.66

d 5 0.92 18.56 24.85
d13 13.40 4.11 0.80
d14 12.83 4.48 1.50
d15 10.00 2.40 2.24
d21 4.28 6.10 3.14
d24 5.54 11.33 14.45
d26 1.68 1.68 1.68

Zoom lens group data group Start surface Focal length
1 1 46.99
2 6 -7.15
3 14 ∞
4 15 ∞
5 16 19.13
6 22 24.47
7 25 ∞

Numerical example 3
Surface data surface number rd nd νd
1 43.831 1.50 1.84666 23.9
2 24.843 4.95 1.69680 55.5
3 123.760 0.18
4 29.043 2.59 1.72000 50.2
5 74.598 (variable)
6 119.287 0.70 1.88300 40.8
7 7.324 3.00
8 -76.430 0.60 1.80610 33.3
9 35.468 0.86
10 -33.821 0.60 1.77250 49.6
11 29.494 0.43
12 18.430 1.80 1.92286 18.9
13 -119.953 (variable)
14 flare cut aperture ∞ (variable)
15 (Aperture) ∞ (Variable)
16 * 10.720 3.66 1.58313 59.4
17 -84.606 2.54
18 21.814 0.60 1.84666 23.9
19 9.481 0.92
20 * 16.084 1.76 1.58313 59.4
21 344.283 (variable)
22 16.502 3.19 1.51742 52.4
23 -15.078 1.00 1.84666 23.9
24 -30.175 (variable)
25 ∞ 2.38 1.54400 60.0
26 ∞ (variable)
Image plane ∞

Aspheric data 16th surface
K = -3.72205e-001 A 4 = -5.19189e-005 A 6 = -1.94531e-007 A 8 = -1.37706e-009

20th page
K = 2.69227e + 000 A 4 = -1.05197e-004 A 6 = -4.26669e-007

Various data Zoom ratio 13.68
Wide angle Medium telephoto focal length 3.80 20.51 52.00
F number 1.85 2.99 3.40
Half angle of view 35.39 8.32 3.30
Total lens length 82.35 82.35 82.35
BF 9.81 15.66 16.47

d 5 0.92 19.79 26.51
d13 14.24 4.33 0.80
d14 13.65 4.69 1.50
d15 9.35 3.23 2.24
d21 3.50 3.77 3.94
d24 6.59 12.45 13.26
d26 1.68 1.68 1.68

Zoom lens group data group Start surface Focal length
1 1 43.86
2 6 -7.35
3 14 ∞
4 15 ∞
5 16 20.09
6 22 27.03
7 25 ∞

Numerical example 4
Surface data surface number rd nd νd
1 42.792 1.50 1.84666 23.9
2 25.170 5.05 1.69680 55.5
3 154.383 0.18
4 31.666 2.10 1.77250 49.6
5 66.931 (variable)
6 49.056 0.70 1.88300 40.8
7 7.183 3.02
8 51.578 0.60 1.80610 33.3
9 12.169 2.00
10 -29.366 0.60 1.80 400 46.6
11 49.709 0.17
12 17.312 1.85 1.92286 18.9
13 -130.408 (variable)
14 flare cut aperture ∞ (variable)
15 (Aperture) ∞ (Variable)
16 * 10.326 3.17 1.58313 59.4
17 -70.871 2.52
18 27.526 0.60 1.80518 25.4
19 9.496 0.73
20 * 16.776 1.89 1.58313 59.4
21 -78.312 (variable)
22 21.427 3.12 1.48749 70.2
23 -13.416 1.00 1.84666 23.9
24 -21.553 (variable)
25 ∞ 2.38 1.54400 60.0
26 ∞ (variable)
Image plane ∞

Aspheric data 16th surface
K = -5.42643e-001 A 4 = -3.52948e-005 A 6 = -1.38456e-007 A 8 = -3.21814e-009

20th page
K = 4.38239e + 000 A 4 = -1.63504e-004 A 6 = -1.34942e-006

Various data Zoom ratio 9.70
Wide angle Medium telephoto focal length 3.80 17.93 36.86
F number 1.85 2.99 3.40
Half angle of view 38.28 9.50 4.65
Total lens length 81.05 81.05 81.05
BF 8.75 14.97 18.07

d 5 0.92 18.19 24.35
d13 13.33 4.09 0.80
d14 12.39 4.36 1.50
d15 9.84 2.52 2.24
d21 5.00 6.10 3.27
d24 5.53 11.75 14.86
d26 1.68 1.68 1.68

Zoom lens group data group Start surface Focal length
1 1 45.02
2 6 -7.29
3 14 ∞
4 15 ∞
5 16 18.50
6 22 28.80
7 25 ∞

Numerical Example 5
Surface data surface number rd nd νd
1 47.001 1.70 1.84666 23.9
2 27.239 5.74 1.69680 55.5
3 129.829 0.18
4 30.509 2.82 1.75500 52.3
5 72.033 (variable)
6 104.169 0.70 1.88300 40.8
7 7.316 2.55
8 71.209 0.60 1.80610 33.3
9 17.933 1.74
10 -16.924 0.60 1.81600 46.6
11 188.776 0.20
12 24.496 1.79 1.92286 18.9
13 -45.604 (variable)
14 flare cut aperture ∞ (variable)
15 (Aperture) ∞ (Variable)
16 * 10.532 3.16 1.58313 59.4
17 -78.865 2.50
18 24.868 0.60 1.80518 25.4
19 9.676 0.70
20 * 16.278 1.70 1.58313 59.4
21 144.561 (variable)
22 18.493 3.62 1.51823 58.9
23 -11.396 1.00 1.84666 23.9
24 -19.242 (variable)
25 ∞ 2.38 1.54400 60.0
26 ∞ (variable)
Image plane ∞

Aspheric data 16th surface
K = -3.59174e-001 A 4 = -4.50990e-005 A 6 = -2.13965e-007 A 8 = -3.16289e-009

20th page
K = 3.45398e + 000 A 4 = -1.65946e-004 A 6 = -1.09432e-006

Various data Zoom ratio 11.71
Wide angle Medium Telephoto focal length 3.50 18.48 41.00
F number 1.85 2.99 3.40
Half angle of view 37.65 9.22 4.18
Total lens length 84.25 84.25 84.25
BF 9.51 15.74 18.40

d 5 0.92 19.48 26.10
d13 14.01 4.27 0.80
d14 13.47 4.65 1.50
d15 10.91 2.46 2.24
d21 3.53 5.74 3.30
d24 6.29 12.53 15.19
d26 1.68 1.68 1.68

Zoom lens group data group Start surface Focal length
1 1 46.57
2 6 -7.26
3 14 ∞
4 15 ∞
5 16 20.39
6 22 23.72
7 25 ∞

Numerical example 6
Surface data surface number rd nd νd
1 46.276 1.70 1.84666 23.9
2 27.213 5.89 1.65 160 58.5
3 147.917 0.18
4 30.702 2.89 1.75500 52.3
5 78.184 (variable)
6 109.837 0.70 1.88300 40.8
7 7.290 2.78
8 1210.145 0.60 1.80610 33.3
9 19.166 1.62
10 -20.985 0.60 1.83481 42.7
11 98.747 0.28
12 23.626 1.77 1.94595 18.0
13 -50.747 (variable)
14 flare cut aperture ∞ (variable)
15 (Aperture) ∞ (Variable)
16 * 10.057 3.23 1.58313 59.4
17 -92.512 2.50
18 26.777 0.60 1.80518 25.4
19 9.549 0.78
20 * 17.774 1.77 1.58313 59.4
21 -163.410 (variable)
22 16.685 3.53 1.51633 64.1
23 -12.040 1.00 1.84666 23.9
24 -20.828 (variable)
25 ∞ 2.38 1.54400 60.0
26 ∞ (variable)
Image plane ∞

Aspheric data 16th surface
K = -3.42706e-001 A 4 = -5.31259e-005 A 6 = -2.42409e-007 A 8 = -2.92697e-009

20th page
K = 3.06187e + 000 A 4 = -1.34517e-004 A 6 = -4.64413e-007 A 8 = 3.25377e-009

Various data Zoom ratio 9.71
Wide angle Medium telephoto focal length
F number 1.85 2.22 3.40
Half angle of view 37.63 27.85 5.04
Total lens length 82.43 82.43 82.43
BF 8.70 9.31 17.64

d 5 0.92 6.63 24.70
d13 13.01 6.50 0.80
d14 13.07 13.87 1.50
d15 10.00 6.46 2.24
d21 4.31 7.24 3.13
d24 5.49 6.09 14.42
d26 1.68 1.68 1.68

Zoom lens group data group Start surface Focal length
1 1 46.21
2 6 -7.11
3 14 ∞
4 15 ∞
5 16 19.60
6 22 23.21
7 25 ∞

  Next, an embodiment of a video camera using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG. In FIG. 13, reference numeral 10 denotes a video camera body, and 11 denotes a photographing optical system constituted by the zoom lens of the present invention. Reference numeral 12 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 11. Reference numeral 13 denotes a memory for storing information corresponding to the subject image photoelectrically converted by the image sensor 12, and reference numeral 14 denotes a finder for observing the subject image displayed by a display element (not shown). Thus, by applying the zoom lens of the present invention to an imaging apparatus such as a video camera, an imaging apparatus having a small size and high optical performance can be realized. The zoom lens of the present invention can be applied to a digital still camera as well.

  L1 ... first lens group, L2 ... second lens group, L3 ... third lens group, L4 ... fourth lens group, SP ... stop, FC ... flare cut stop IP ... imaging plane, G ... force plate of CCD, Glass block such as low-pass filter, spherical aberration ... solid line: d line, two-dot chain line: g line, astigmatism ... ΔS: d line sagittal image plane, ΔM: d line meridional image plane, distortion ... d line, lateral chromatic aberration ... Two-dot chain line: g line

Claims (9)

In order from the object side to the image side, the lens unit includes a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens group having a positive refractive power. In zooming, the first lens group is stationary during zooming, and the second lens group, the third lens group, and the fourth lens group move.
A zoom lens comprising a flare cut stop having a fixed aperture diameter between the second lens group and the third lens group, the flare cut stop moving during zooming. When the focal length of the entire system at the wide angle end is fw and the focal length of the second lens group is f2,
-2.2 <f2 / fw <-1.8
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the entire system at the wide-angle end is fw and the focal length of the first lens group is f1,
11.0 <f1 / fw <14.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.   The zoom according to any one of claims 1 to 3, wherein the flare-cut stop moves toward the image side or moves along a convex locus toward the object side during zooming from the wide-angle end to the telephoto end. lens.   5. The zoom lens according to claim 1, wherein the flare-cut stop moves independently of the second lens group and the third lens group during zooming. 6. When the amount of movement of the third lens group in zooming from the wide-angle end to the telephoto end is f3st and the amount of movement of the flare cut stop is Sst,
1.2 <Sst / f3st <2.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.   2. The whole or a part of the third lens group is moved so as to have a component in a direction perpendicular to the optical axis, and a photographed image is moved in a direction perpendicular to the optical axis. The zoom lens of any one of thru | or 6.   An image pickup apparatus comprising: the zoom lens according to claim 1; and an image pickup element that receives an image formed by the zoom lens.   9. The image pickup apparatus according to claim 8, wherein image processing is performed such that an effective image circle diameter on the wide angle side is smaller than an effective image circle diameter at the telephoto end.