JP6545021B2 - Zoom lens and imaging device having the same - Google Patents

Description

  The present invention relates to a zoom lens and an imaging apparatus having the same, and is particularly suitable as an imaging optical system used for an imaging apparatus such as a still camera, a video camera, and a digital still camera.

  In recent years, as an imaging optical system used in an imaging apparatus using a solid-state imaging device, a zoom lens having a high zoom ratio and high optical performance over the entire zoom range is required although the entire system is compact. In particular, in the field of interchangeable lens camera systems, it is strongly required that the zoom lens system be a compact system when the camera is carried. It is generally known to use a lens barrel structure called a collapsing type as a technique for reducing the size of the entire system at the time of carrying.

  Here, the collapsing method is a method using a mechanism for reducing the size by shortening and extending the entire lens configuration at the time of carrying by extending and contracting a part of the lens barrel, and for improving the portability. When using this collapsing method, it is necessary to consider both the size at the time of use (during photographing) and the size at the time of the collapsed state.

  For example, it is necessary to reduce the thickness of the lens construction length in the retracted state by reducing the number of lenses constituting each lens group constituting the zoom lens and reducing the thickness of each lens group. In addition, when the overall lens length is too long at the time of use, the entire system becomes large and the imaging operation becomes inconvenient, and therefore it is demanded that the overall lens length be short at the time of use.

  Furthermore, the position of the focus lens in the optical system and the size of the focus lens greatly affect the size of the entire lens barrel. Therefore, as a focusing system, it is required that a focusing lens be compact, aberration fluctuation is small during focusing, high optical performance be obtained over the entire object distance range, and a focusing system suitable for a collapsing system, etc. .

  Conventionally, the first lens group of negative refractive power, the second lens group of positive refractive power, in order from the object side to the image side as a compact zoom lens having a relatively small zoom ratio and a relatively high zoom ratio, There is known a three-unit zoom lens composed of a third lens unit of negative refractive power (Patent Documents 1 and 2). Patent Documents 1 and 2 disclose a zoom lens in which all lens groups move during zooming, the distance between adjacent lens groups changes, and the third lens group closest to the image moves during focusing.

Unexamined-Japanese-Patent No. 2006-308929 JP, 2008-158121, A

  In the above-described three-unit zoom lens, it is relatively easy to achieve a high zoom ratio while achieving downsizing of the entire system. However, in order to obtain a zoom lens having such features, it is necessary to appropriately set the movement locus of each lens unit during zooming, the refractive power of each lens unit constituting the zoom lens, and the lens configuration of each lens unit. Is important. In particular, it is important to shorten the lens construction length of each lens group (the distance from the lens surface on the most object side of the lens group to the lens surface on the most image side) in order to miniaturize the entire system when collapsed. It will come.

  Besides, in order to use as a zoom lens for a lens interchangeable camera, it is important to have a back focus of an appropriate length. In addition, when used in an imaging apparatus in which an autofocus mechanism is mounted, it is also required that the autofocus operation be fast and easy.

  The zoom lens of Patent Document 1 has a too short back focus and is difficult to apply to a lens-interchangeable camera system. The zoom lens of Patent Document 2 has a tendency that the outer diameter of the focus lens is large as compared with the entire size, and the entire lens barrel becomes large.

  An object of the present invention is to provide a zoom lens in which the entire lens system is compact and has a high zoom ratio and high optical performance easily in the entire zoom range, and an image pickup apparatus having the same. Another object of the present invention is to provide a zoom lens having an appropriate length of back focus suitable for, for example, a lens-interchangeable camera system and capable of easily miniaturizing the entire system in the collapsed state, and an imaging device having the same.

The zoom lens according to the present invention includes a first lens unit of negative refractive power and a second lens unit of positive refractive power, which are disposed in order from the object side to the image side .
Or
It comprises the first lens group, the second lens group, and a third lens group of negative refractive power, which are disposed in order from the object side to the image side.
A zoom lens in which at least the first lens group and the second lens group move during zooming, and the distance between adjacent lens groups changes.
On the most image side of the zoom lens, a focusing lens of negative refractive power that moves during focusing is disposed,
The first lens group is composed of one negative lens and one positive lens ,
The focal length of the first lens group is f1, the back focus at the wide angle end is skw , and the distance from the lens surface of the lens group closest to the object to the lens surface closest to the image is the lens group length. Let Bd be the sum of the component lengths of the lens and Lw be the total lens length at the wide-angle end .
0.8 <| f1 | / skw <1.4
0.20 <Bd / Lw <0.27
It is characterized by satisfying the following conditional expression.

  According to the present invention, it is possible to obtain a zoom lens in which the entire lens system is compact, a high zoom ratio, and easily high optical performance in the entire zoom range.

Diagram of lens cross section and movement locus at the wide-angle end in Example 1 (A), (B), (C) Various aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end according to Example 1. Diagram of lens cross section and movement locus at the wide-angle end in Example 2 (A), (B), (C) Various aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end of Example 2. Diagram of lens cross section and movement locus at the wide-angle end in Example 3 (A), (B), (C) Various aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end of Example 3. Embodiments of the Digital Camera of the Present Invention

Hereinafter, the zoom lens of the present invention and an imaging device having the same will be described based on the drawings. The zoom lens according to the present invention is composed of, in order from the object side to the image side, a first lens unit of negative refractive power and a second lens unit of positive refractive power , or arranged in order from the object side to the image side. It comprises the first lens group, the second lens group, and the third lens group of negative refractive power. A focusing lens of negative refractive power is disposed closest to the image, and during zooming, the first lens group and the second lens group move, and the distance between adjacent lens groups changes. Here, the lens unit is a lens element that moves integrally during zooming, and it is sufficient if it has one or more lenses, and it is not necessary to necessarily have a plurality of lenses.

  FIG. 1 is a cross-sectional view of a zoom lens at a wide angle end (short focal length end) according to a first exemplary embodiment of the present invention. FIGS. 2A, 2B, and 2C are aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end (long focal length end) of the zoom lens according to the first embodiment of the present invention. The first embodiment is a zoom lens having a zoom ratio of 2.84 and an aperture ratio (F number) of 3.60 to 6.40.

  FIG. 3 is a lens sectional view of a zoom lens at the wide-angle end according to a second embodiment of the present invention. FIGS. 4A, 4B, and 4C are aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end of the zoom lens according to Embodiment 2 of the present invention. The second embodiment is a zoom lens having a zoom ratio of 2.86 and an aperture ratio of 3.60 to 6.40.

  FIG. 5 is a lens sectional view of a zoom lens at the wide-angle end according to a third embodiment of the present invention. FIGS. 6A, 6B, and 6C are aberration diagrams at the wide-angle end, the middle zoom position, and the telephoto end of the zoom lens according to Embodiment 3 of the present invention. The third embodiment is a zoom lens having a zoom ratio of 2.88 and an aperture ratio of 3.60 to 6.40. FIG. 7 is a schematic view of the essential portions of a digital camera (image pickup apparatus) having a zoom lens according to the present invention.

  The zoom lens of each embodiment is an imaging optical system used for an imaging device, and in the lens sectional view, the left side is the object side (front) and the right side is the image side (rear). The zoom lens of each embodiment may be used for an optical apparatus such as a projector. In this case, the left side is the screen and the right side is the projection image.

  In the lens sectional view, L0 is a zoom lens. Further, B1 is a first lens group of negative refractive power (optical power = reciprocal of focal length), and B2 is a second lens group of positive refractive power. FL is a focusing lens of negative refractive power located closest to the image side. SP is an F-number determining member (hereinafter also referred to as "aperture stop") that acts as an aperture stop that determines (limits) an open F-number (Fno) luminous flux.

  GS is an optical block corresponding to an optical filter, a face plate, a quartz low pass filter, an infrared cut filter, and the like. IP is an image plane, and when used as an imaging optical system of a video camera or a digital still camera, an imaging surface of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is placed.

  In FIGS. 1 and 3, the focusing lens FL is a lens group that moves independently (with a different locus) from the other lens groups during zooming, and corresponds to the third lens group B3. In FIG. 5, when the focus lens FL is in focus at infinity, it moves integrally (with the same locus) as the second lens unit B2 during zooming.

  Therefore, when focusing at infinity, it can be handled as a two-group zoom lens. When focusing is performed at a finite distance, the lens unit moves independently from the other lens units during zooming. Therefore, when focusing at a finite distance, it can be handled as a three-unit zoom lens. However, on the basis of focusing at infinity, in Embodiment 3, the focusing lens FL is treated as a part of the second lens unit B2 and treated as a two-unit zoom lens. In the lens cross-sectional view, the arrow indicates the movement locus of each lens unit during zooming from the wide angle end to the telephoto end.

  An arrow 3a relating to the third lens group B3 and an arrow 2a relating to the second lens group B2 indicate a movement locus during zooming from the wide-angle end to the telephoto end when focusing at infinity. The arrow 3b relating to the third lens group B3 and the arrow 2b relating to part of the second lens group B2 indicate a movement locus during zooming from the wide-angle end to the telephoto end when focusing at a short distance. An arrow 3c relating to the third lens group B3 and an arrow 2c relating to a part of the second lens group B2 indicate the movement direction during focusing from infinity to near distance.

  Among the aberration diagrams, in the spherical aberration diagram, d represents d-line (wavelength 587.6 nm) and g represents g-line (wavelength 435.8 nm). Fno is an F number. In the astigmatism diagram, ΔM is a meridional image plane of d-line, and ΔS is a sagittal image plane of d-line. Lateral chromatic aberration is represented by g-line. ω is a half angle of view (degree). In each of the following embodiments, the wide-angle end and the telephoto end refer to zoom positions when the magnification varying lens unit is located at both ends of the movable range on the optical axis.

  In the zoom lens according to the present invention, in order to secure a sufficient zoom ratio while having high optical performance, the first lens unit B1 having at least negative refractive power and the first lens unit having positive refractive power are sequentially arranged from the object side to the image side. It has a two-lens group B2. A focusing lens with negative refractive power is positioned closest to the image side. And, by optimizing the refractive power of each lens group and the movement locus at the time of zooming, etc., while having high optical performance, a back focus of an appropriate length is secured along with the downsizing of the entire system, and the collapsed state We are trying to miniaturize the entire system.

  Generally, in an optical system in which a lens unit of negative refractive power and a lens unit of positive refractive power are arranged in order from the object side to the image side, relatively high optical performance can be obtained with a small number of lenses. In addition, since the number of lenses is small, the entire system can be easily downsized in the retracted state, which is suitable for the retraction mechanism.

  In the zoom lens of the present invention, the lens closest to the image side has a relatively small effective lens diameter in the entire system. Therefore, by arranging the focus lens at or near the position here, the downsizing of the entire system is achieved while the downsizing of the focusing mechanism including the mechanical mechanism is achieved. However, when the entire system is miniaturized, the effective lens diameter of the lens closest to the image side tends to be large when the back focus is short. This is because the incident height at which the off-axis ray passes through the lens surface closest to the image becomes higher as the lens closest to the image side approaches the image pickup element.

  Therefore, it is important to be configured to obtain a back focus of a predetermined length while disposing the focus lens closest to the image. Furthermore, when applied as an imaging optical system for a lens-interchangeable imaging device, it is necessary to secure a back focus of an appropriate length for a connection mechanism of the imaging device and the lens barrel.

Therefore, in each embodiment, in order to ensure a back focus of an appropriate length while maintaining high optical performance, the following condition (1) is satisfied. That is, the first lens group B1 is composed of one negative lens and one positive lens, and the focal length of the first lens group B1 is f1 and the back focus at the wide angle end is skw. At this time,
0.8 <| f1 | / skw <1.4 (1)
To satisfy the following conditional expression.

  Next, the technical meaning of the above-mentioned conditional expression (1) is demonstrated. Condition (1) relates to the ratio of the back focus at the wide angle end to the absolute value of the focal length of the first lens unit B1. If the upper limit value of the conditional expression (1) is exceeded, it will be difficult to secure a back focus of a predetermined length. If the negative focal length of the first lens unit B1 becomes too short (if the absolute value of the negative focal length decreases) beyond the lower limit value of the conditional expression (1), the field curvature increases at the wide angle end, It is difficult to correct this aberration and it becomes difficult to obtain high optical performance.

  By adopting the above configuration, it is possible to easily obtain a zoom lens of high optical performance over the entire zoom range with a small size of the entire system and a high zoom ratio. In each embodiment, it is more preferable to satisfy at least one of the following conditional expressions.

When the second lens unit B2 does not include the focus lens, the focal length of the second lens unit B2 is f2, and when the second lens unit B2 includes the focus lens, the second lens unit excluding the focus lens The focal length of the optical system constituting B2 is f2. The distance from the lens surface closest to the object side to the lens surface closest to the image is referred to as the lens group length, the sum of lens lengths of all lens groups is Bd, and the total lens length at the wide angle end is Lw.

The focal length of the entire system (zoom lens) at the wide angle end is fw. The focal length of the entire system at the telephoto end is ft. The second lens group B2 has an aspheric lens including at least one aspheric lens surface, and the Abbe number of the material of the aspheric lens is B2v. The Abbe number dd of the material is Nd, NF, NC, and the refractive indices of the d-line, F-line, and C-line of the Fraunhofer line,
d d = (Nd-1) / (NF-NC)
Defined by

The total lens length is a distance obtained by adding the value of back focus in air conversion to the length from the first lens surface to the final lens surface. At this time, it is preferable to satisfy one or more of the following conditional expressions.
0.30 <f2 / skw <0.85 (2)
0.20 <Bd / Lw < 0.27 (3)
0.5 <f2 / fw <1.3 (4)
1.3 <| f1 | / fw <2.0 (5)
1.2 <| f1 | / f2 <1.8 (6)
0.1 <f2 / ft <0.5 (7)
0.3 <| f1 | / ft <0.7 (8)
B2 v> 60.0 (9)

  Next, technical meanings of the above-mentioned conditional expressions will be described. In the conditional expression (2), when the focal length of the second lens group B2 or the second lens group B2 includes the focus lens, the focal length f2 when the focus lens is removed from the second lens group B2 and On the back focus skw ratio. If the upper limit value of the conditional expression (2) is exceeded, it will be difficult to secure a back focus of a predetermined length. If the focal length of the second lens unit B2 becomes too short beyond the lower limit value of the conditional expression (2), spherical aberration increases at the telephoto end, and correction of this aberration becomes difficult, making it difficult to obtain high optical performance. Become.

  Condition (3) relates to the ratio of the sum of the thicknesses of the lens units to the total lens length at the wide-angle end. If the total of the thicknesses of the lens units becomes large beyond the upper limit value of the conditional expression (3), it becomes difficult to miniaturize the entire system at the time of retraction. If the total lens length at the wide-angle end is too long beyond the lower limit value of the conditional expression (3), the collapsing mechanism becomes large and it becomes difficult to miniaturize the whole system at the time of collapsing.

  Conditional expression (4) indicates that when the focal length of the second lens unit B2 or the second lens unit B2 includes the focus lens, the focal length when the focus lens is removed from the second lens unit B2 and the entire distance at the wide angle end. It relates to the ratio to the focal length of the system. If the focal length f2 becomes too long beyond the upper limit value of the conditional expression (4), the total lens length becomes long, and the entire system becomes large. If the focal length f2 becomes too short beyond the lower limit value of the conditional expression (4), coma due to an off-axis ray increases at the wide angle end, and it becomes difficult to correct this aberration.

  Condition (5) relates to the ratio of the focal length of the first lens unit B1 to the focal length of the entire system at the wide-angle end. If the negative focal length of the first lens unit B1 becomes too long (if the absolute value of the negative focal length becomes large) beyond the upper limit value of the conditional expression (5), the total lens length increases and the entire system becomes large Come on. If the negative focal length of the first lens unit B1 becomes too short beyond the lower limit value of the conditional expression (5), field curvature increases at the wide-angle end, and correction of this aberration becomes difficult.

  In the conditional expression (6), when the focal length of the first lens group B1 and the focal length of the second lens group B2 or the second lens group B2 includes the focusing lens, the focusing lens is excluded from the second lens group B2. It relates to the ratio to the focal length. If the negative focal length of the first lens unit B1 becomes too long beyond the upper limit value of the conditional expression (6), the total lens length increases, and the entire system becomes large. If the negative focal length of the first lens unit B1 becomes too short beyond the lower limit value of the conditional expression (6), field curvature increases at the wide angle end, and it becomes difficult to correct this aberration.

  Conditional expression (7) indicates that when the focal length of the second lens unit B2 or the second lens unit B2 includes the focus lens, the focal length and the entire distance at the telephoto end when the focus lens is removed from the second lens unit B2 It relates to the ratio to the focal length of the system. If the focal length f2 becomes too long beyond the upper limit value of the conditional expression (7), the total lens length becomes large. If the focal length f2 becomes too short beyond the lower limit value of the conditional expression (7), spherical aberration increases at the telephoto end, and this aberration correction becomes difficult.

  Condition (8) relates to the ratio of the negative focal length of the first lens unit B1 to the focal length of the entire system at the telephoto end. If the negative focal length of the first lens unit B1 becomes too long beyond the upper limit value of the conditional expression (8), the total lens length increases, and the entire system becomes large. If the negative focal length of the first lens unit B1 becomes too short beyond the lower limit value of the conditional expression (8), spherical aberration increases at the telephoto end, and it becomes difficult to correct this aberration.

  Condition (9) relates to the Abbe number of the material of the aspheric lens when the second lens group B2 has an aspheric lens including at least one aspheric lens surface. In the second lens unit B2, the incident height of the axial ray increases. For this reason, while the correction of the spherical aberration is favorably performed by disposing the aspheric lens in the second lens group B2, the correction of the axial chromatic aberration is favorably performed by using the low dispersion material.

In each embodiment, it is more preferable to set the numerical range of the conditional expressions (1) to (9) as follows.
0.8 <| f1 | / skw <1.2 (1a)
0.5 <f2 / skw <0.7 (2a)
0.24 <Bd / Lw <0.27 (3a)
0.8 <f2 / fw <1.2 (4a)
1.45 <| f1 | / fw <1.85 (5a)
1.30 <| f1 | / f2 <1.75 (6a)
0.30 <f2 / ft <0.45 (7a)
0.30 <| f1 | / ft <0.65 (8a)
B2 v> 65.0 (9a)

It is still more preferable to set the numerical range of the conditional expressions (1a) to (9a) as follows.
0.88 <| f1 | / skw <1.02 (1b)
0.59 <f2 / skw <0.64 (2b)
0.245 <Bd / Lw <0.270 (3b)
1.04 <f2 / fw <1.15 (4b)
1.58 <| f1 | / fw <1.80 (5b)
1.38 <| f1 | / f2 <1.72 (6b)
0.35 <f2 / ft <0.40 (7b)
0.50 <| f1 | / ft <0.64 (8b)
B2v> 70.0 (9b)

As described above, according to the present invention, it is possible to obtain a compact zoom lens in a retracted state while having a sufficient zoom ratio with high optical performance and securing a back focus of an appropriate length. The zoom lens according to the present invention includes a first lens unit B1 of negative refractive power and a second lens unit B2 of positive refractive power , which are disposed in order from the object side to the image side. The first lens unit B1 may be composed of a negative lens having an aspheric lens surface and a positive lens, which are disposed in order from the object side to the image side. By reducing the number of lenses constituting the first lens unit B1, downsizing of the entire system in the retracted state can be facilitated.

When the third lens group B3 of negative refractive power is disposed adjacent to the image side of the second lens group B2, the third lens group B3 is composed of one negative lens, and the third lens group B3 should move during focusing. By simplifying the lens configuration of the focus lens and reducing the weight, it becomes easy to miniaturize the entire system including the drive mechanism and the like. More preferably, the focus lens may have an aspheric surface. According to this, appropriate aberration correction becomes possible with a small number of lenses.

Preferably, a negative lens is disposed on the most image side of the second lens unit B2, and the negative lens is a focus lens that moves during focusing. At this time, it is preferable that the second lens unit B2 be composed of a positive lens, a negative lens, a positive lens, and a negative lens, which are disposed in order from the object side to the image side.

  When the zoom lens of the present invention is used in an image pickup apparatus having an image pickup element, it is preferable to have a correction means for correcting distortion by image processing. Further, in recent years, it is common to correct distortion by image processing, and the distortion can be easily downsized by assuming that the correction is performed by image processing.

  Next, an embodiment of a digital still camera (image pickup apparatus) using the zoom lens of the present invention as an image pickup optical system will be described with reference to FIG.

  In FIG. 7, reference numeral 20 denotes a camera body, and 21 denotes a photographing optical system constituted by any one of the zoom lenses described in the first to third embodiments. Reference numeral 22 denotes a solid-state imaging device such as a CCD sensor or a CMOS sensor which is built in the camera body and receives an object image formed by the photographing optical system 21. Reference numeral 23 denotes a memory for recording information corresponding to an object image photoelectrically converted by the solid-state image sensor 22. Reference numeral 24 denotes a finder for observing an object image formed on the solid-state image sensor 22 which is constituted by a display panel such as a liquid crystal display.

  Next, numerical data of the embodiment of the present invention will be shown. In each numerical data, i indicates the order of the surface from the object side, and ri is the radius of curvature of the lens surface. di is a lens thickness and an air gap between the i-th surface and the (i + 1) -th surface. ndi and νdi indicate the refractive index and the Abbe number for the d-line, respectively. * Indicates that it is an aspheric surface. The two surfaces closest to the image are glass materials such as a face plate. Further, k is an eccentricity, and A4, A6, A8, A10 and A12 are aspheric coefficients.

When the displacement in the direction of the optical axis at the position of height h from the optical axis is x with respect to the surface apex,
x = (h ² / R) / [1+ {1− (1 + k) (h / R) ² } ^1/2 ] + A4 · h ⁴ + A6 · h ⁶ + A8 · h ⁸ + A10 · h ¹⁰ + A12 · h ¹²
Is represented by Where R is a paraxial radius of curvature.

"E-z" means "10 ^-z". The back focus BF is indicated by an air equivalent distance from the lens surface closest to the image to the image plane. The total lens length is a value obtained by adding back focus to the distance from the first lens surface to the final lens surface. Regarding the angle of view, it is a numerical value of the half angle of view (ω) with respect to the image captureable angle of view in which the amount of distortion is taken into consideration. Further, the relationship between each of the conditional expressions described above and each numerical example is shown in Table 1.

Example 1
Unit mm

Surface data surface number rd nd d d
1 * 64.183 1.20 1.85400 40.4
2 * 11.554 4.54
3 16.570 3.00 1.92286 18.9
4 24.664 (variable)
5 * 16.597 5.00 1.55332 71.7
6 -8.412 0.70 1.83400 37.2
7 28.866 0.59
8 * 67.218 3.55 1.85400 40.4
9 *-10.941 1.00
10 (stop) ∞ (variable)
11 * 48.267 1.24 1.90270 31.0
12 * 18.711 (variable)
13 1. 1.70 1.54400 60.0
14 ∞ 2.16
Image plane ∞

Aspheric data first surface
K = 0.00000e + 000A 4 = -1.05153e-006 A 6 =-4.73154e-008 A 8 = 2.54857e-010
A10 = -3.41198e-013

Second side
K = -3.70989e-001 A 4 = 6.32035e-006 A 6 = 5.95802e-009 A 8 =-1.21623e-009
A10 = 7.13011e-012

Fifth side
K = 0.00000e + 000A 4 =-1.01038e-004 A 6 =-2.01236e-007 A 8 =-4.04295e-008
A10 = -1.84857e-010

Eighth side
K = 0.00000e + 000 A 4 = -1.99866e-005 A 6 = -1.48900e-006 A 8 = -1.64181e-009
A10 = 8.70316e-010 A12 = -3.88283e-011

9th surface
K = 0.00000e + 000 A 4 = 7.73803e-005 A 6 =-2.49 335e-006 A 8 =-9. 9634 4e-010
A10 = 8.83591e-010 A12 = −2.98086e-011

11th
K = 0.00000e + 000 A 4 = 1.72487e-004 A 6 =-9.64512e-006 A 8 = 1.96669e-007
A10 = -1.56792e-009

12th
K = 0.00000e + 000 A 4 = 1.21227e-004 A 6 = -8.38279e-006 A 8 = 1.90763e-007
A10 = -1.70992e-009

Various data zoom ratio 2.84

Focal length 15.50 36.00 44.00 18.78 29.00 23.00
F number 3.60 5.60 6.40 3.90 4.91 4.32
Half angle of view (degrees) 36.84 20.78 17.25 33.21 25.22 30.71
Image height 11.61 13.66 13.66 12.29 13.66 13.66
Lens total length 78.58 73.73 77.66 74.33 71.82 72.09
BF 27.26 45.50 52.65 30.08 39.33 33.93

d 4 27.51 4.80 1.69 20.48 8.97 14.51
d10 3.00 2.62 2.50 2.96 2.71 2.84
d12 24.00 42.24 49.39 26.82 36.07 30.67

Zoom lens group data group Start focal length
1 1-27.57
2 5 16.26
FL 11-34.54
G 13 ∞

Example 2
Unit mm

Surface data surface number rd nd d d
1 * 60.726 1.20 1.85400 40.4
2 * 10.717 4.51
3 15.943 3.25 1.92286 18.9
4 23.690 (variable)
5 * 13.120 5.00 1.49700 81.5
6 -9.722 0.70 1.83400 37.2
7 26.460 0.56
8 * 74.569 3.04 1.85400 40.4
9 * -11.010 1.00
10 (stop) ∞ (variable)
11 * 47.288 1.24 1.90270 31.0
12 * 20.154 (variable)
13 1. 1.70 1.54400 60.0
14 ∞ 2.11
Image plane ∞

Aspheric data first surface
K = 0.00000e + 000A 4 = -4.41749e-006 A 6 =-9.51907e-008 A 8 = 7.29913e-010
A10 = -1.36658e-012

Second side
K = -3.61359e-001 A 4 =-1.09661e-006 A 6 =-1.03900e-007 A 8 =-1.53136e-009
A10 = 1.31970e-011

Fifth side
K = 0.00000e + 000A 4 = -1. 17179e-004 A 6 =-4.798422-007 A 8 =-3.97525e-008
A10 = -8.87032e-010

Eighth side
K = 0.00000e + 000A 4 =-2.49727e-005 A 6 =-1.43040e-006 A 8 = 3.67276e-009
A10 = 1.04761e-009 A12 =-2.97419e-011

9th surface
K = 0.00000e + 000A 4 = 7.20239e-005 A 6 = -2.58400e-006 A 8 =-5.00389e-009
A10 = 9.20314e-010 A12 =-2.64927e-011

11th
K = 0.00000e + 000 A 4 = 1.66282e-004 A 6 = -9.22248e-006 A 8 = 1.87402e-007
A10 = -2.07551e-009

12th
K = 0.00000e + 000 A 4 = 1.17401e-004 A 6 = -7.82921e-006 A 8 = 1.82788e-007
A10 = -2.4082e-009

Various data zoom ratio 2.86

Focal length 15.39 36.00 44.00 18.71 29.00 23.00
F number 3.60 5.61 6.40 3.91 4.92 4.33
Half angle of view (degrees) 37.03 20.78 17.25 33.31 25.22 30.71
Image height 11.61 13.66 13.66 12.29 13.66 13.66
Lens total length 75.84 74.56 79.23 72.33 71.66 70.91
BF 27.21 46.62 54.16 30.09 39.95 34.19

d 4 25.14 4.83 2.08 18.71 8.46 13.32
d10 3.00 2.61 2.50 3.03 2.75 2.91
d12 24.00 43.41 50.95 26.88 36.74 30.98

Zoom lens group data group Start focal length
1 1-25.00
2 5 16.70
FL 11 -39.77
G 13 ∞

[Example 3]
Unit mm

Surface data surface number rd nd d d
1 * 72.006 1.20 1.85400 40.4
2 * 10.868 4.39
3 15.790 2.80 1.92286 18.9
4 23.492 (variable)
5 0.00 0.00
6 * 15.765 5.50 1.55332 71.7
7-7.137 0.70 1.70154 41.2
8 42.290 0.81
9 * -89.872 2.97 1.85400 40.4
10 * -11.813 1.00
11 (aperture) ∞ 3.00
12 * -84.487 1.24 1.84666 23.8
13 * 86.822 (variable)
14 ∞ 1.70 1.54400 60.0
15 ∞ 2.32
Image plane ∞

Aspheric data first surface
K = 0.00000e + 000A 4 = -3.66144e-007 A 6 =-1.40349e-008 A 8 = 1.39124e-011
A10 = 4.01649e-013

Second side
K = -2.34777e-001 A 4 =-8.77195e-006 A 6 = 3.81434e-008 A 8 =-2.55818e-009
A10 = 5.52324e-012

Sixth face
K = 0.00000e + 000A 4 = -5.73756e-005 A 6 = 5.59025e-007 A 8 =-1.23783e-008
A10 = 2.62373 e-010

9th surface
K = 0.00000e + 000 A 4 = -1.03927e-004 A 6 =-3.34313e-006 A 8 = 2.09617e-008
A10 = -3.42334e-009 A12 = 6.45846e-011

Face 10
K = 0.00000e + 000A 4 = -1.06913e-005 A 6 =-3.22164e-006 A 8 = 6. 80900e-009
A10 = -1.10819e-009 A12 = 1.68837e-011

12th
K = 0.00000e + 000A 4 = 4.37130e-004 A 6 =-12.21066e-005 A 8 = 1.93606e-007
A10 = 3.23073e-011

13th surface
K = 0.00000e + 000 A 4 = 4.16528e-004 A 6 =-9.44819e-006 A 8 = 1.25761e-007
A10 = 6.44978e-010

Various data zoom ratio 2.88

Focal length 15.27 36.00 44.00 18.80 29.00 23.00
F number 3.60 5.61 6.40 3.94 4.93 4.35
Half angle of view (degrees) 37.24 20.78 17.25 33.19 25.22 30.71
Image height 11.61 13.66 13.66 12.29 13.66 13.66
Lens total length 75.10 73.59 78.13 71.68 70.84 70.25
BF 27.42 46.25 53.52 30.62 39.89 34.44

d 4 24.08 3.73 1.00 17.45 7.35 12.20
d13 24.00 42.83 50.10 27.20 36.47 31.02

Zoom lens group data group Start focal length
1 1 -24.37
2 5 17.37
FL 12-50.41
G 14 ∞

B1 First lens unit B2 Second lens unit B3 Third lens unit FL Focus lens

Claims (13)

The first lens unit having negative refractive power and the second lens unit having positive refractive power, which are disposed in order from the object side to the image side .
Or
It comprises the first lens group, the second lens group, and a third lens group of negative refractive power, which are disposed in order from the object side to the image side.
A zoom lens in which at least the first lens group and the second lens group move during zooming, and the distance between adjacent lens groups changes.
On the most image side of the zoom lens, a focusing lens of negative refractive power that moves during focusing is disposed,
The first lens group is composed of one negative lens and one positive lens ,
The focal length of the first lens group is f1, the back focus at the wide angle end is skw , and the distance from the lens surface of the lens group closest to the object to the lens surface closest to the image is the lens group length. Let Bd be the sum of the component lengths of the lens and Lw be the total lens length at the wide-angle end .
0.8 <| f1 | / skw <1.4
0.20 <Bd / Lw <0.27
A zoom lens characterized by satisfying the following conditional expression. When the focus lens is not included in the second lens group, the focal length of the second lens group is f2, and when the focus lens is included in the second lens group, the second lens excluding the focus lens Assuming that the focal length of the optical system constituting the group is f2,
0.30 <f2 / skw <0.85
The zoom lens according to claim 1, which satisfies the following conditional expression. When the focus lens is not included in the second lens group, the focal length of the second lens group is f2, and when the focus lens is included in the second lens group, the second lens excluding the focus lens Assuming that the focal length of the optical system constituting the group is f2, and the focal length of the zoom lens at the wide angle end is fw,
0.5 <f2 / fw <1.3
The zoom lens according to claim 1 or 2 , wherein the following conditional expression is satisfied. Assuming that the focal length of the zoom lens at the wide angle end is fw,
1.3 <| f1 | / fw <2.0
The zoom lens according to any one of claims 1 to 3 , wherein the following conditional expression is satisfied. When the focus lens is not included in the second lens group, the focal length of the second lens group is f2, and when the focus lens is included in the second lens group, the second lens excluding the focus lens Assuming that the focal length of the optical system constituting the group is f2,
1.2 <| f1 | / f2 <1.8
The zoom lens according to any one of claims 1 to 4 , wherein the following conditional expression is satisfied. When the focus lens is not included in the second lens group, the focal length of the second lens group is f2, and when the focus lens is included in the second lens group, the second lens excluding the focus lens Assuming that the focal length of the optical system constituting the group is f2, and the focal length of the zoom lens at the telephoto end is ft,
0.1 <f2 / ft <0.5
The zoom lens according to any one of claims 1 to 5 , wherein the following conditional expression is satisfied. When the focal length of the zoom lens at the telephoto end is ft,
0.3 <| f1 | / ft <0.7
The zoom lens according to any one of claims 1 to 6 , wherein the following conditional expression is satisfied. The second lens group has an aspheric lens including an aspheric lens surface, and the Abbe number of the material of the aspheric lens is B2v.
B2v> 60.0
The zoom lens according to any one of claims 1 to 7 , wherein the following conditional expression is satisfied. The zoom lens according to any one of claims 1 to 8 , wherein the one negative lens has an aspheric lens surface. The second lens group according to any one of claims 1 to 9 , wherein the second lens group includes a positive lens, a negative lens, a positive lens, and a negative lens, which are disposed in order from the object side to the image side. Zoom lens. The zoom lens according to any one of claims 1 to 10 , wherein, when the zoom lens has the third lens group, the third lens group is configured of one negative lens. An image pickup apparatus comprising the zoom lens according to any one of claims 1 to 11 and an image pickup element for receiving an image formed by the zoom lens. 13. The image pickup apparatus according to claim 12 , further comprising a correction unit configured to correct distortion by image processing.