JP2018197774A - Zoom lens and imaging apparatus having the same - Google Patents

Abstract

To obtain a small-sized zoom lens capable of easily obtaining favorable optical characteristics over an entire zoom range with a high zoom ratio.SOLUTION: A zoom lens includes a first lens group of positive refractive power, a second lens group of negative refractive power, and a rear group having a plurality of lens groups that are arranged from an object side to an image side in order, and in which an interval of adjoining lens groups changes at a time of zooming. From among a plurality of lens groups included in the rear group, the lens group Ln of negative refractive power is arranged closest to an image, and each of a focal distance f1 of the first lens group, focal distance f2 of the second lens group, composite focal distance f12 of the first lens group and the second lens group at a wide angle end, and a focal distance frw of the rear group at a wide angle end are suitably set.SELECTED DRAWING: Figure 1

Description

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

In recent years, an image pickup apparatus using a solid-state image pickup element has been downsized, and an image pickup element used for the image pickup apparatus has been increased in the number of pixels.
An imaging optical system used in such an imaging apparatus is required to have high optical performance and to be small in size.

  As a zoom lens that satisfies these requirements, a positive lens unit including a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a rear group including a plurality of lens groups in order from the object side to the image side. A lead type zoom lens is known.

Patent Documents 1 and 2 are composed of first to fifth lens units having positive, negative, positive, positive, and negative refractive power in order from the object side to the image side, and each lens unit is moved to perform zooming. A zoom lens that performs focusing with a small fourth lens group is disclosed.
Patent Document 3 includes first to sixth lens groups having positive, negative, positive, negative, positive, and negative refractive powers in order from the object side to the image side, and performs zooming by moving each lens group. A zoom lens that performs focusing by moving the sixth lens group is disclosed.

JP, 2015-064491, A Japanese Unexamined Patent Publication No. 2015-066904 Japanese Patent Laid-Open No. 04-186212

  A positive lead type zoom lens is relatively easy to achieve a large aperture ratio, a wide angle of view, and a high zoom ratio while reducing the size of the entire system.

In the positive lead type zoom lens described above, a large zoom ratio is obtained by giving a strong negative refractive power to the second lens group. However, since the second lens group is disposed at a position where the off-axis chief ray is away from the optical axis at the wide-angle end, off-axis aberration tends to increase when a strong negative refractive power is applied to the second lens group. There is.
In such a positive lead type zoom lens, in order to obtain high optical performance in the entire zoom range, it is important to appropriately set the refractive power and lens configuration of each lens group.

  If this configuration is not appropriate, the entire system will become larger when the aperture ratio is increased, and fluctuations in various aberrations associated with zoom will increase. Therefore, high resolution will be obtained over the entire zoom range and the entire screen. Becomes very difficult.

  For example, when the aperture ratio is increased, the refractive power of each lens group is increased to shorten the overall length of the lens by shortening the distance between the lens groups, thereby achieving high resolution in the entire zoom range. It becomes difficult. Particularly when the F-number is small and the aperture ratio is bright, it is extremely difficult to satisfactorily correct various aberrations with a small number of lenses. Therefore, it is important to appropriately set the refractive power and lens configuration of each lens group constituting the zoom lens.

  The zoom lenses disclosed in Patent Documents 1 and 2 have a negative refracting power in the lens group closest to the image side and move the principal point to the object side, thereby reducing the overall size while shortening the back focus. ing. However, if the F-number is about 3.5 to 5.6 and if the aperture ratio is further increased, high-order aberrations such as spherical aberration are often generated, and it is difficult to correct these various aberrations. In Patent Documents 1 and 2, since the number of lenses constituting the image side lens unit is smaller than that of the aperture stop, the lens surface cannot be sufficiently disposed at a position where the off-axis principal ray is separated from the optical axis. There was a tendency for correction of surface curvature and the like to be difficult.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a small zoom lens that can easily obtain good optical characteristics over a whole zoom range with a high zoom ratio, and an imaging apparatus having the same.

The zoom lens of the present invention has a rear group including a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a plurality of lens groups, which are arranged in order from the object side to the image side. A zoom lens in which an interval between adjacent lens groups changes during zooming, and a lens group Ln having a negative refractive power is disposed closest to the image side among the plurality of lens groups included in the rear group.
The focal length of the first lens group is f1, the focal length of the second lens group is f2, the combined focal length of the first lens group and the second lens group at the wide-angle end is f12, and the rear group at the wide-angle end is When the focal length is frw,
−8.0 <f1 / f2 <−5.5
−1.08 <f12 / frw <−0.95
It satisfies the following conditional expression.

  According to the present invention, it is possible to obtain a small zoom lens that can easily obtain good optical characteristics over the entire zoom range with a high zoom ratio.

Lens cross-sectional view at the wide-angle end of the zoom lens of Example 1 Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 1. Lens sectional view at the wide-angle end of the zoom lens according to Embodiment 2 Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 2. Lens sectional view at the wide-angle end of the zoom lens according to Embodiment 3 Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 3 Lens sectional view at the wide-angle end of the zoom lens according to Embodiment 4 Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 4. 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 of the present invention has a rear group including a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a plurality of lens groups, which are arranged in order from the object side to the image side. The distance between adjacent lens units changes during zooming. Among the plurality of lens groups included in the rear group, the lens group Ln having a negative refractive power is disposed closest to the image side.

  FIG. 1 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to Embodiment 1 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 F number of 2.26 to 2.91.

  FIG. 3 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 2 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. Example 2 is a zoom lens having a zoom ratio of 2.37 and an F number of 2.24 to 2.91.

  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 exemplary embodiment is a zoom lens having a zoom ratio of 2.36 and an F number of 2.27 to 2.91.

  FIG. 7 is a lens cross-sectional view at the wide-angle end of the zoom lens according to a 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. The fourth exemplary embodiment is a zoom lens having a zoom ratio of 2.35 and an F number of 2.25 to 2.91. FIG. 9 is a schematic diagram of a main part of the imaging apparatus of the present invention.

The zoom lens of each embodiment is an imaging optical system used in imaging devices such as a video camera, a digital camera, a TV camera, a surveillance camera, and a silver salt film camera. In the lens cross-sectional view, the left side is the subject side (object side) (front), and the right side is the image side (rear). In the lens cross-sectional view, i indicates the order of the lens groups from the object side, and Li is the i-th lens group.
LR is a rear group including a plurality of lens groups. Ln is a lens unit having a negative refractive power arranged on the most image side among a plurality of lens groups included in the rear group LR.

  In the lens cross-sectional view, SP is an aperture stop, which is disposed on the object side of the third lens unit L3. IP is an image plane. When used as an imaging optical system for a video camera or a digital still camera, a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is on the image plane, and a silver salt film camera. Is provided with a photosensitive surface corresponding to the film surface.

  The arrows indicate the movement direction and movement locus of each lens group during zooming (magnification) from the wide-angle end to the telephoto end. The arrow related to the focus indicates the moving direction of the lens group when focusing from infinity to a short distance.

  Among spherical aberrations in the aberration diagrams, the solid line d-line is the d line (wavelength 587.6 nm), and the broken line g-line is the g line (wavelength 435.8 nm). In the astigmatism diagram, the broken line ΔM is the d-line meridional image plane, and the solid line ΔS is the d-line sagittal image plane. The lateral chromatic aberration g-line is the g-line with respect to the d-line. ω is a half angle of view (a value half of the shooting angle of view) (degrees), and Fno is an F number.

  In the lens cross-sectional views of Examples 1, 2, and 4, L1 is a first lens group having a positive refractive power, L2 is a second lens group having a negative refractive power, and LR is a rear group. The rear group LR includes a third lens unit L3 having a positive refractive power, a fourth lens unit L4 having a positive refractive power, and a fifth lens unit L5 having a negative refractive power which are arranged in order from the object side to the image side. . Examples 1, 2, and 4 are 5-group zoom lenses. In Examples 1, 2, and 4, the first lens unit L1 to the fifth lens unit L5 move during zooming.

  In the lens cross-sectional view of Example 3, L1 is a first lens group having a positive refractive power, L2 is a second lens group having a negative refractive power, and LR is a rear group. The rear group LR includes a third lens unit L3 having a positive refractive power, a fourth lens unit L4 having a negative refractive power, a fifth lens unit L5 having a positive refractive power, and a negative refraction arranged in order from the object side to the image side. The sixth lens unit L6 is composed of a force. Example 3 is a 6-group zoom lens. In Example 3, the first to sixth lens units L1 to L6 move during zooming.

  In each embodiment, the aperture stop SP moves integrally (with the same locus) with the third lens unit L3 during zooming, but may move independently (with a different locus). In each embodiment, the aperture diameter of the aperture stop SP may be constant during zooming or may be changed according to zooming. When the aperture diameter of the aperture stop SP is changed during zooming, off-axis marginal rays can be cut and coma flare can be reduced, so that better optical performance can be easily obtained.

  The zoom lens according to each embodiment includes a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, and a lens unit including a plurality of lens units, which are sequentially arranged from the object side to the image side. It is composed of LR. A lens group Ln having a negative refractive power is disposed on the most image side among the plurality of lens groups included in the rear group LR. By making the lens unit Ln closest to the image plane of the rear group LR have a negative refractive power, the principal point is moved to the object side, the back focus is shortened, and the whole is shortened.

  In order to reduce the amount of movement during zooming, the second lens unit L2 has a strong negative refractive power. In the second lens unit L2, the off-axis principal ray passes through a high position from the optical axis at the wide-angle end, and various aberrations such as field curvature and lateral chromatic aberration are likely to occur.

  Therefore, in each embodiment, the lens unit Ln having a negative refractive power is disposed on the most image side of the rear unit LR. Thereby, the on-axis marginal ray of the lens unit Ln is close to the optical axis, and the off-axis principal ray passes through a high position from the optical axis in the direction opposite to that of the second lens unit L2. Thereby, field curvature, lateral chromatic aberration, etc. are corrected satisfactorily.

In the zoom lens of the present invention, the focal length of the first lens unit L1 is f1, the focal length of the second lens unit L2 is f2, and the combined focal length of the first lens unit L1 and the second lens unit L2 at the wide angle end is f12. The combined focal length of the rear group LR at the wide angle end is defined as frw. At this time,
−8.0 <f1 / f2 <−5.5 (1)
-1.08 <f12 / frw <-0.95 (2)
The following conditional expression is satisfied.

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (1) defines the ratio between the focal length of the first lens unit L1 and the focal length of the second lens unit L2. The negative refractive power of the second lens unit L2 becomes stronger as the negative focal length of the second lens unit L2 is shorter (the absolute value of the negative focal length is smaller) than the focal length of the first lens unit L1. The amount of movement of the second lens unit L2 can be reduced during zooming. As a result, the entire system can be easily downsized. If the upper limit of conditional expression (1) is exceeded and the negative refractive power of the second lens unit L2 becomes weak, the amount of movement of the second lens unit L2 increases during zooming, making it difficult to reduce the size of the entire system.

  On the other hand, if the negative refractive power of the second lens unit L2 becomes stronger than the lower limit of the conditional expression (1), the amount of movement of the second lens unit L2 during zooming decreases, which is advantageous for downsizing of the entire system. . However, various aberrations are generated more than in the second lens unit L2, and correction of various aberrations becomes difficult. Further, since the positive refractive power of the first lens unit L1 is weakened, the amount of movement during zooming of the first lens unit L1 increases, which is not preferable. The numerical value range of conditional expression (1) is preferably set as follows.

−7.5 <f1 / f2 <−5.7 (1a)
More preferably, the numerical range of conditional expression (1a) should be as follows.
−7.0 <f1 / f2 <−5.9 (1b)

  Conditional expression (2) defines the ratio of the combined focal length of the first lens unit L1 and the second lens unit L2 at the wide angle end to the focal length of the rear group LR at the wide angle end.

  In the zoom lens of the present invention, the aperture stop SP is substantially disposed between the second lens group L2 and the rear group LR. Thus, conditional expression (2) is the ratio of the focal length of the object-side lens unit and the focal length of the image-side lens unit across the aperture stop SP. A wide-angle positive-lead type zoom lens has a front lens group having a negative refractive power on the object side of the aperture stop SP at the wide-angle end and a rear side of positive refractive power on the image side of the aperture stop SP. A so-called reverse telephoto refractive power arrangement is adopted, which is a lens configuration in which the lens group is arranged. By increasing the negative refractive power of the front lens group, it becomes easy to obtain a long back focus.

  In the zoom lens of the present invention, it is sufficient if there is a back focus of a predetermined length. Further, when the negative refractive power of the front lens group becomes strong and the balance of the refractive power with the rear lens group having a positive refractive power is lost, the optical performance is deteriorated. In particular, the Petzval sum increases, and many off-axis aberrations such as field curvature and distortion occur, making it difficult to correct these various aberrations. If the numerical value range of the conditional expression (2) is not satisfied, the refractive power balance between the front lens group and the rear lens group is lost, and many off-axis aberrations such as field curvature and distortion occur at the wide-angle end. Since correction is difficult, it is not preferable.

Preferably, the numerical range of conditional expression (2) should be as follows.
-1.06 <f12 / frw <-0.98 (2a)
More preferably, the numerical range of conditional expression (2a) should be as follows.
-1.04 <f12 / frw <-1.00 (2b)

  With the configuration as described above, the zoom lens according to the present invention can be obtained, but it is more preferable that at least one of the following conditions is satisfied, and according to this, even higher optical performance is achieved. Is easily obtained.

  The back focus at the wide angle end is skdw, and the focal length of the entire system at the wide angle end is fw. The lens group Ln has one negative lens and one positive lens, and the focal length of the lens group Ln is fn. Let ft be the focal length of the entire system at the telephoto end, and Lt be the length on the optical axis from the lens surface closest to the object side to the image plane at the telephoto end.

At this time, it is preferable to satisfy one or more of the following conditional expressions.
0.50 <skdw / fw <0.90 (3)
0.10 <f2 / fn <0.30 (4)
0.20 <ft / Lt <0.60 (5)

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (3) defines the ratio of the back focus to the focal length of the entire system at the wide angle end. The zoom lens of the present invention shortens the total lens length by appropriately setting the back focus at the wide angle end. When conditional expression (3) is a small value, it is advantageous for downsizing of the entire system.

  However, if the back focus is too short below the lower limit of conditional expression (3), the angle of incidence of the off-axis principal ray on the image plane becomes tight, and shading in which the peripheral part of the image becomes darker than the central part. Becomes notable, and this correction becomes difficult. On the other hand, if the back focus increases beyond the upper limit of conditional expression (3), the total lens length becomes longer, which is not preferable. The numerical value range of conditional expression (3) is preferable.

0.60 <skdw / fw <0.80 (3a)
More preferably, the numerical range of conditional expression (3a) should be as follows.
0.65 <skdw / fw <0.75 (3b)

  Conditional expression (4) defines the ratio between the focal length of the second lens unit L2 and the focal length of the lens unit Ln having the negative refractive power arranged closest to the image side in the rear unit LR.

  The zoom lens of the present invention increases the negative refractive power of the second lens unit L2, thereby reducing the amount of movement of the second lens unit L2 during zooming, thereby reducing the overall lens length. In particular, the off-axis aberration generated from the second lens unit L2 at the wide-angle end is corrected by the lens unit Ln arranged at a position where the axial marginal ray is low and the incident height of the off-axis principal ray is high.

  When the negative refractive power of the second lens unit L2 is increased below the lower limit of the conditional expression (4), the amount of movement during zooming of the second lens unit L2 is reduced, which is advantageous for downsizing the entire lens length. However, the negative refractive power of the lens unit Ln becomes weak and the balance of aberration correction is lost, which is not preferable.

On the other hand, if the upper limit of conditional expression (4) is exceeded and the negative refractive power of the second lens unit L2 becomes weak, the movement amount during zooming of the second lens unit L2 increases and the total lens length becomes longer. Absent. The numerical value range of conditional expression (4a) is preferable.
0.13 <f2 / fn <0.28 (4a)
More preferably, the numerical range of conditional expression (4a) should be as follows.
0.17 <f2 / fn <0.26 (4b)

  Conditional expression (5) defines the ratio between the focal length of the entire system at the telephoto end and the total lens length of the entire system. When the upper limit of conditional expression (5) is exceeded and the focal length of the entire system becomes longer than the total lens length at the telephoto end, the total lens length becomes shorter and the entire system becomes smaller. However, the absolute value of the refractive power of each lens group becomes very large, and various aberrations occur from each lens group, making it difficult to correct the various aberrations.

On the other hand, if the total lens length with respect to the focal length of the entire system at the telephoto end is less than the lower limit of the conditional expression (5), the entire system becomes undesirably large. Preferably, the numerical range of conditional expression (5) should be as follows.
0.25 <ft / Lt <0.55 (5a)
More preferably, the numerical range of conditional expression (5a) should be as follows.
0.30 <ft / Lt <0.50 (5b)

  Next, the lens configuration of each example will be described. First, a lens configuration common to each embodiment will be described. In each embodiment, the first lens unit L1 having a positive refractive power, the second lens unit L2 having a negative refractive power, an aperture stop SP, and a plurality of lens units arranged in order from the object side to the image side are positive as a whole. And a rear group LR of refracting power. When focusing from infinity to a short distance, the second lens unit moves to the object side. In addition, the lens unit Ln disposed on the most image side in the rear unit LR has a negative refractive power. Next, the lens configuration in each embodiment will be described.

[Example 1]
With reference to FIG. 1, the lens configuration of Example 1 of the present invention will be described. In Example 1, the rear group LR includes a third lens group L3, a fourth lens group L4, and a fifth lens group L5. In Example 1, the lens unit Ln having a negative refractive power arranged on the most image side of the rear group LR is the fifth lens unit L5. By making the most image side lens unit of the zoom lens of Example 1 have a negative refractive power, the principal point is moved to the object side, the back focus, which is the distance between the lens surface and the image surface, is shortened, and the entire system is moved. The size is reduced.

  The first lens unit L1 includes a cemented lens in which a negative meniscus lens having a convex surface facing the object side and a positive lens are cemented together, and a meniscus positive lens having a convex surface facing the object side. With this configuration, various aberrations such as coma and spherical aberration at the telephoto end are corrected well. The second lens unit L2 has an aspherical surface on the object side, a negative lens having negative refractive power on the image side, a negative lens having a concave shape on both sides, and a negative lens having a concave shape on both sides and a positive lens. It consists of a cemented lens, a positive lens, and a negative lens. With this configuration, it is possible to reduce aberration fluctuations in the entire zoom range and the entire object distance, and achieve good optical performance.

  The third lens unit L3 includes a cemented lens in which a negative lens having a convex surface facing the object side and a positive lens are cemented together, a positive lens having a convex shape on the object side, an aspherical shape on the image side, and a negative lens having a concave surface facing the image side, It consists of a negative lens with a concave surface facing the object side. By adopting a configuration in which the number of negative lenses is larger than that of the positive lenses, the amount of aberration that each negative lens corrects the aberration generated from the positive lens is shared.

  In addition, by sharing the refracting power of each negative lens, the radius of curvature and the refractive index are reduced to facilitate correction of aberrations. Further, the third lens unit L3 is disposed at a position where the on-axis marginal ray is separated from the optical axis in the entire zoom range. By configuring the third lens unit L3 in this way, high-order spherical aberration that occurs when the aperture ratio is increased is favorably corrected.

  The fourth lens unit L4 includes two positive lenses having convex surfaces on both sides, a negative lens having an aspherical shape on the image side and a concave surface on both sides, a negative lens having a concave shape on both sides and a positive lens having an aspheric surface on the image side. It consists of a cemented lens. The fifth lens unit L5 includes a cemented lens obtained by cementing a negative lens having a concave shape on both sides and a positive lens. With this configuration, the lateral chromatic aberration generated from the second lens unit L2 is corrected well.

  In zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves to the object side, and the second lens unit L2 moves to the image side, so that the distance between the first lens unit L1 and the second lens unit L2 is reached. Is spreading. Further, the third lens unit L3, the fourth lens unit L4, and the fifth lens unit L5 are moved to the object side.

[Example 2]
Hereinafter, the lens configuration of Example 2 of the present invention will be described with reference to FIG. In Example 2, the rear group LR includes a third lens group L3, a fourth lens group L4, and a fifth lens group L5. In Example 2, the lens unit Ln having a negative refractive power disposed on the most image side of the rear group LR is the fifth lens unit L5.

  The first lens unit L1 includes a cemented lens obtained by cementing a negative meniscus lens having a convex surface on the object side and a positive lens, and a meniscus positive lens having a convex surface facing the object side. The second lens unit L2 has an aspherical shape on the object side and a negative lens having negative refractive power on the image side, a negative lens having a concave shape on both sides, a cemented lens in which a negative lens having a concave shape on both sides and a positive lens are cemented, It is composed of a negative meniscus lens having a convex surface facing the image side. The third lens unit L3 is a cemented lens obtained by cementing a negative meniscus lens having a convex surface toward the object side and a positive lens, a positive lens, a negative lens having an aspheric shape on the image side, and a negative lens having a concave surface directed toward the object side. It is configured.

  The fourth lens unit L4 includes two positive lenses having convex surfaces on both sides, a negative lens having an aspheric shape on the image side, and a cemented lens in which a negative lens and a positive lens having an aspheric shape on the image side are cemented. The fifth lens unit L5 includes a negative lens having a concave surface on both sides and a meniscus positive lens having a convex surface on the object side.

[Example 3]
Hereinafter, with reference to FIG. 5, the lens configuration of Example 3 of the present invention will be described. In Example 3, the rear group LR includes a third lens group L3, a fourth lens group L4, a fifth lens group L5, and a sixth lens group L6. In Example 3, the lens unit Ln having a negative refractive power disposed on the most image side of the subsequent lens unit LR is the sixth lens unit L6.

  The first lens unit L1 includes a cemented lens obtained by cementing a negative meniscus lens having a convex surface on the object side and a positive lens, and a meniscus positive lens having a convex surface facing the object side. The second lens unit L2 has an aspherical shape on the object side, a negative lens having negative refractive power on the image side, a negative lens having a concave surface on both sides, a negative lens having a concave shape on both sides, and a cemented lens in which a positive lens is cemented A positive lens and a negative lens. The third lens unit L3 includes a cemented lens in which a negative lens having a convex surface facing the object side and a positive lens are cemented.

  The fourth lens unit L4 includes a positive lens having a convex shape on the object side, an aspheric shape on the image side, a negative lens having a concave surface facing the image side, and a negative lens having a concave surface facing the object side. The fifth lens unit L5 includes two positive lenses having convex surfaces on both sides, a negative lens having an aspherical shape on the image side and a concave surface on both sides, a negative lens having a concave shape on both sides and a positive lens having an aspheric surface on the image side. It consists of a cemented lens. The sixth lens unit L6 includes a cemented lens obtained by cementing a negative lens having a concave shape on both sides and a positive lens.

  In zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves to the object side, and the second lens unit L2 moves to the image side, so that the distance between the first lens unit L1 and the second lens unit L2 is reached. Is spreading. Further, the third lens unit L3, the fourth lens unit L4, the fifth lens unit L5, and the sixth lens unit L6 are moved to the object side.

[Example 4]
With reference to FIG. 7, the lens configuration of Example 4 of the present invention will be described. In Example 4, the rear group LR includes a third lens group L3, a fourth lens group L4, and a fifth lens group L5. In Example 4, the lens unit Ln having a negative refractive power disposed on the most image side of the rear group LR is the fifth lens unit L5.

  The first lens unit L1 includes a cemented lens in which a negative meniscus lens having a convex surface facing the object side and a positive lens are cemented together, and a meniscus positive lens having a convex surface facing the object side. The second lens unit L2 has an aspherical shape on the object side and a negative lens having negative refractive power on the image side, a negative lens having a concave shape on both sides, a cemented lens in which a negative lens having a concave shape on both sides and a positive lens are cemented, It consists of a positive lens and a negative lens. The third lens unit L3 includes a cemented lens in which a negative lens having a convex surface directed toward the object side and a positive lens are cemented, a positive lens having convex surfaces on both sides, a negative lens having an aspheric shape on the image side and a concave surface directed to the image side, an object It is composed of a negative lens with a concave surface on the side.

  The fourth lens unit L4 includes two positive lenses having convex surfaces on both sides, a negative lens having an aspherical shape on the image side and a concave surface on both sides, a negative lens having a concave surface on both sides and an aspherical positive lens on the image side. It consists of a cemented lens. The fifth lens unit L5 includes a cemented lens obtained by cementing a negative lens having a concave shape on both sides and a positive lens.

  In zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves to the object side, and the second lens unit L2 moves to the image side, so that the distance between the first lens unit L1 and the second lens unit L2 is reached. Is spreading. Further, the third lens unit L3, the fourth lens unit L4, and the fifth lens unit L5 are moved to the object side.

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

  In FIG. 9, reference numeral 10 denotes a camera body, and 11 denotes an imaging 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 imaging optical system 11 and is built in the camera body.

  Next, numerical data 1 to 4 corresponding to the first to fourth embodiments of the present invention will be shown. In each numerical data, i indicates the order of the optical surfaces from the object side. ri is the radius of curvature of the i-th optical surface (i-th surface), di is the distance between the i-th surface and the i + 1-th surface, and ndi and νdi are the refractions of the material of the i-th optical member with respect to the d-line, respectively. Indicates the rate and Abbe number.

BF is a back focus, and represents the distance from the final lens surface to the paraxial image surface as an air-converted length. The total lens length is a length obtained by adding the value of the back focus BF to the length from the first lens surface to the final lens surface. * Means an aspherical surface. K is the eccentricity. A4, A6, A8, A10, and A12 are aspherical coefficients. The aspherical shape is defined as x when the displacement in the optical axis direction at the position of the height h from the optical axis with respect to the surface vertex is x.
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
It is represented by

Where R is the paraxial radius of curvature. “E−x” means “10 ^−x ”. Table 1 shows the correspondence between the above-described conditional expressions and parameters in each numerical data.

[Numeric data 1]
Unit mm

Surface data surface number rd nd νd Effective diameter
1 124.697 1.87 1.85478 24.8 82.36
2 80.530 10.11 1.49700 81.5 77.17
3 507.325 1.00 75.88
4 54.737 9.35 1.59522 67.7 67.33
5 146.676 (variable) 65.77
6 * 103.102 2.00 1.55332 71.7 44.75
7 18.344 9.44 30.30
8 -90.538 2.00 1.58913 61.1 29.93
9 109.450 4.81 26.91
10 -48.582 2.00 1.58913 61.1 24.27
11 28.098 3.36 1.74950 35.3 22.04
12 9587.206 0.66 21.56
13 -1277.727 1.57 1.80518 25.4 21.09
14 -111.804 3.15 20.69
15 -22.285 2.00 1.64000 60.1 21.03
16 -32.405 (variable) 22.62
17 (Aperture) ∞ 0.34 24.63
18 24.842 1.76 1.85478 24.8 26.91
19 21.215 5.14 1.59522 67.7 26.15
20 230.293 0.89 26.01
21 47.086 2.95 1.49700 81.5 25.64
22 2698.974 0.38 25.29
23 93.245 1.58 1.76802 49.2 24.77
24 * 44.951 3.51 23.80
25 -49.748 1.30 1.72047 34.7 23.79
26 -77.463 (variable) 24.12
27 25.163 5.89 1.43875 94.9 24.59
28 -115.589 0.88 24.03
29 38.987 5.38 1.53775 74.7 24.46
30 -69.481 0.68 24.11
31 -119.370 1.87 1.76802 49.2 23.61
32 * 88.586 1.45 23.06
33 -349.038 1.25 1.85400 40.4 23.08
34 21.496 7.28 1.55332 71.7 23.76
35 * -36.665 (variable) 24.55
36 -38.155 2.00 1.53775 74.7 25.97
37 30.787 4.03 1.74950 35.3 29.90
38 135.812 30.16
Image plane ∞

Aspheric data 6th surface
K = 0.00000e + 000 A 4 = 3.54364e-006 A 6 = -2.28371e-009 A 8 = 6.59402e-012 A10 = -9.15886e-015 A12 = 1.08663e-017

24th page
K = 0.00000e + 000 A 4 = 1.22800e-005 A 6 = 1.87008e-008 A 8 = 3.34108e-011 A10 = 2.18542e-013 A12 = 1.02835e-016

32nd page
K = 0.00000e + 000 A 4 = 1.81324e-005 A 6 = 3.30095e-008 A 8 = -2.20578e-010 A10 = 2.43717e-012 A12 = -3.79206e-015

35th page
K = 0.00000e + 000 A 4 = 8.65896e-006 A 6 = -3.28848e-008 A 8 = 4.17946e-010 A10 = -1.87108e-012

Various data Zoom ratio 2.37
Wide angle Medium Telephoto focal length 28.68 44.13 67.90
F number 2.26 2.63 2.91
Half angle of view (degrees) 37.03 26.12 17.67
Image height 21.64 21.64 21.64
Total lens length 149.69 159.09 174.43
BF 20.57 29.09 35.45

d 5 3.29 14.93 30.53
d16 14.05 6.54 1.76
d26 5.63 2.53 0.94
d35 4.28 4.12 3.89

Entrance pupil position 49.14 71.90 116.87
Exit pupil position -38.15 -34.10 -32.15
Front principal point position 63.81 85.21 116.57
Rear principal point position -8.11 -15.03 -32.45

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 118.76 22.33 3.10 -11.37
2 6 -19.46 30.99 6.42 -17.94
3 17 52.42 17.83 -5.01 -16.47
4 27 38.12 24.68 2.91 -15.68
5 36 -78.13 6.03 0.85 -2.71

Single lens Data lens Start surface Focal length
1 1 -271.28
2 2 191.10
3 4 141.35
4 6 -40.67
5 8 -83.80
6 10 -29.93
7 11 37.59
8 13 152.08
9 15 -120.81
10 18 -218.95
11 19 38.90
12 21 96.39
13 23 -114.63
14 25 -196.85
15 27 47.71
16 29 47.26
17 31 -65.95
18 33 -23.67
19 34 25.63
20 36 -31.37
21 37 52.26

Focus wide angle infinity close (380mm)
d5 3.29 0.30
Middle infinity Close (380mm)
d5 14.93 11.09
Telephoto Infinity Close (380mm)
d5 30.53 24.87

[Numeric data 2]
Unit mm

Surface data surface number rd nd νd Effective diameter
1 143.049 1.87 1.84666 23.8 83.20
2 90.061 8.98 1.53775 74.7 78.33
3 557.138 1.00 76.90
4 52.706 9.19 1.53775 74.7 64.42
5 146.017 (variable) 62.78
6 * 113.662 2.00 1.55332 71.7 46.11
7 18.448 9.08 30.97
8 -273.341 2.00 1.49700 81.5 30.56
9 67.894 3.95 27.01
10 -42.972 1.50 1.58913 61.1 26.37
11 30.977 3.76 1.85026 32.3 24.04
12 -209.738 5.32 23.59
13 -21.903 1.99 1.65160 58.5 20.90
14 -30.020 (variable) 22.45
15 (Aperture) ∞ 0.13 24.43
16 27.366 1.76 1.80518 25.4 26.24
17 23.138 4.45 1.59522 67.7 25.72
18 180.113 1.00 25.64
19 38.469 3.40 1.49700 81.5 25.50
20 -3276.064 0.10 25.19
21 145.737 1.58 1.76802 49.2 24.93
22 * 47.296 3.38 24.07
23 -49.769 1.30 1.72047 34.7 24.07
24 -68.804 (variable) 24.43
25 27.611 6.48 1.49700 81.5 25.07
26 -76.156 0.30 24.42
27 46.024 5.18 1.59522 67.7 24.56
28 -72.611 0.10 24.13
29 -100.122 1.87 1.76802 49.2 23.94
30 * 68.373 1.62 23.28
31 -483.880 1.25 1.85400 40.4 23.30
32 25.844 5.41 1.55332 71.7 23.91
33 * -49.734 (variable) 24.37
34 -107.231 2.00 1.49700 81.5 25.50
35 57.595 6.24 26.94
36 45.335 4.10 1.84666 23.8 33.29
37 58.337 33.34
Image plane ∞

Aspheric data 6th surface
K = 0.00000e + 000 A 4 = 3.82952e-006 A 6 = -2.35841e-009 A 8 = 6.97910e-012 A10 = -9.84110e-015 A12 = 1.09151e-017

22nd page
K = 0.00000e + 000 A 4 = 9.77434e-006 A 6 = 6.57964e-009 A 8 = 5.16528e-011 A10 = -1.90305e-014 A12 = 4.15680e-017

30th page
K = 0.00000e + 000 A 4 = 1.51821e-005 A 6 = 4.17287e-008 A 8 = -2.60811e-010 A10 = 2.37380e-012 A12 = -3.34393e-015

Side 33
K = 0.00000e + 000 A 4 = 1.05428e-005 A 6 = -3.12520e-008 A 8 = 3.52963e-010 A10 = -1.68501e-012

Various data Zoom ratio 2.37
Wide angle Medium Telephoto focal length 28.62 44.08 67.90
F number 2.24 2.59 2.91
Half angle of view (degrees) 37.09 26.14 17.67
Image height 21.64 21.64 21.64
Total lens length 150.00 159.07 174.67
BF 19.60 29.31 38.59

d 5 3.60 15.28 29.97
d14 15.31 7.03 1.66
d24 6.79 3.62 1.99
d33 2.45 1.57 0.20

Entrance pupil position 48.84 70.81 110.16
Exit pupil position -45.71 -40.20 -37.10
Front principal point position 64.92 86.93 117.15
Rear principal point position -9.02 -14.77 -29.31

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 122.05 21.03 2.54 -11.12
2 6 -20.53 29.59 6.24 -17.33
3 15 56.45 17.09 -4.69 -15.83
4 25 39.23 22.21 0.60 -14.58
5 34 -116.86 12.34 0.90 -8.61

Single lens Data lens Start surface Focal length
1 1 -291.89
2 2 198.44
3 4 148.27
4 6 -40.10
5 8 -109.22
6 10 -30.33
7 11 31.97
8 13 -137.65
9 16 -228.35
10 17 44.14
11 19 76.53
12 21 -91.81
13 23 -257.02
14 25 41.64
15 27 48.11
16 29 -52.65
17 31 -28.70
18 32 31.54
19 34 -75.09
20 36 209.90

Focus wide angle infinity close (380mm)
d5 3.60 0.30
Middle infinity Close (380mm)
d5 15.28 11.08
Telephoto Infinity Close (380mm)
d5 29.97 23.99

[Numeric data 3]
Unit mm

Surface data surface number rd nd νd Effective diameter
1 124.546 1.87 1.85478 24.8 82.19
2 80.583 10.12 1.49700 81.5 77.05
3 514.812 1.00 75.97
4 54.741 9.36 1.59522 67.7 67.36
5 146.877 (variable) 65.80
6 * 103.673 2.00 1.55332 71.7 44.77
7 18.386 9.53 30.36
8 -90.747 2.00 1.58913 61.1 29.85
9 109.536 4.74 26.86
10 -48.497 2.00 1.58913 61.1 24.31
11 27.947 3.42 1.74950 35.3 22.09
12 8967.645 0.63 21.60
13 -1177.961 1.63 1.80518 25.4 21.16
14 -112.702 3.30 20.68
15 -22.282 2.00 1.64000 60.1 21.06
16 -32.358 (variable) 22.65
17 (Aperture) ∞ 0.23 24.69
18 24.839 1.76 1.85478 24.8 26.91
19 21.278 5.13 1.59522 67.7 26.16
20 231.318 (variable) 26.02
21 47.044 2.95 1.49700 81.5 25.64
22 2852.776 0.37 25.29
23 93.158 1.58 1.76802 49.2 24.77
24 * 44.973 3.48 23.79
25 -49.600 1.30 1.72047 34.7 23.79
26 -77.727 (variable) 24.12
27 25.167 5.89 1.43875 94.9 24.60
28 -115.700 0.88 24.04
29 39.024 5.36 1.53775 74.7 24.47
30 -69.619 0.66 24.12
31 -119.228 1.87 1.76802 49.2 23.63
32 * 88.545 1.45 23.08
33 -351.186 1.25 1.85400 40.4 23.10
34 21.414 7.31 1.55332 71.7 23.77
35 * -36.653 (variable) 24.57
36 -38.097 2.00 1.53775 74.7 26.02
37 30.705 4.14 1.74950 35.3 29.98
38 138.261 30.25
Image plane ∞

Aspheric data 6th surface
K = 0.00000e + 000 A 4 = 3.59424e-006 A 6 = -2.55909e-009 A 8 = 7.56618e-012 A10 = -1.08330e-014 A12 = 1.16769e-017

24th page
K = 0.00000e + 000 A 4 = 1.23703e-005 A 6 = 1.89202e-008 A 8 = 3.38639e-011 A10 = 2.29993e-013 A12 = 6.16266e-017

32nd page
K = 0.00000e + 000 A 4 = 1.79548e-005 A 6 = 3.26411e-008 A 8 = -2.25063e-010 A10 = 2.42921e-012 A12 = -3.90741e-015

35th page
K = 0.00000e + 000 A 4 = 8.45223e-006 A 6 = -3.15408e-008 A 8 = 4.00275e-010 A10 = -1.76868e-012

Various data Zoom ratio 2.36
Wide angle Medium Tele focal length 28.82 44.24 67.90
F number 2.27 2.63 2.91
Half angle of view (degrees) 36.90 26.06 17.67
Image height 21.64 21.64 21.64
Total lens length 150.08 159.44 174.76
BF 20.56 29.08 35.42

d 5 3.29 14.84 30.36
d16 13.96 6.53 1.80
d20 0.97 0.94 0.92
d26 5.71 2.64 1.10
d35 4.40 4.22 3.96

Entrance pupil position 49.29 71.97 116.91
Exit pupil position -38.36 -34.28 -32.37
Front principal point position 64.01 85.32 116.80
Rear principal point position -8.26 -15.15 -32.48

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 118.35 22.34 3.11 -11.37
2 6 -19.42 31.24 6.48 -18.02
3 17 49.24 7.12 -0.87 -5.19
4 21 -349.50 9.67 22.32 13.76
5 27 38.23 24.68 2.92 -15.67
6 36 -78.72 6.14 0.85 -2.77

Single lens Data lens Start surface Focal length
1 1 -272.42
2 2 190.75
3 4 141.26
4 6 -40.73
5 8 -83.93
6 10 -29.81
7 11 37.40
8 13 154.67
9 15 -121.20
10 18 -224.74
11 19 39.01
12 21 96.21
13 23 -114.84
14 25 -193.99
15 27 47.72
16 29 47.32
17 31 -65.90
18 33 -23.60
19 34 25.58
20 36 -31.30
21 37 51.81

Focus wide angle infinity close (380mm)
d5 3.29 0.30
Middle infinity Close (380mm)
d5 14.84 11.01
Telephoto Infinity Close (380mm)
d5 30.36 24.71

[Numeric data 4]
Unit mm

Surface data surface number rd nd νd Effective diameter
1 126.480 1.87 1.85478 24.8 81.94
2 85.129 9.35 1.49700 81.5 78.65
3 427.779 1.00 77.80
4 57.854 9.23 1.59522 67.7 69.49
5 137.663 (variable) 67.61
6 * 73.563 2.00 1.55332 71.7 43.39
7 17.746 11.39 29.97
8 -85.618 2.00 1.58913 61.1 26.18
9 90.833 3.83 23.41
10 -40.095 2.00 1.58913 61.1 21.74
11 30.396 2.76 1.74950 35.3 20.14
12 -1218.765 0.60 20.47
13 4748.952 1.45 1.80518 25.4 20.85
14 -128.777 2.69 21.16
15 -20.071 2.00 1.64000 60.1 21.20
16 -25.686 (variable) 22.90
17 (Aperture) ∞ 0.10 24.47
18 24.860 1.76 1.85478 24.8 26.72
19 21.180 5.11 1.59522 67.7 26.00
20 243.752 1.04 25.88
21 47.089 2.98 1.49700 81.5 25.55
22 -8114.666 0.38 25.23
23 92.532 1.58 1.76802 49.2 24.72
24 * 45.108 3.44 23.79
25 -50.563 1.30 1.72047 34.7 23.78
26 -75.627 (variable) 24.13
27 25.082 5.82 1.43875 94.9 24.57
28 -118.895 0.69 24.04
29 38.492 5.50 1.53775 74.7 24.39
30 -71.056 0.60 24.02
31 -118.399 1.87 1.76802 49.2 23.59
32 * 89.357 1.44 23.07
33 -366.885 1.25 1.85400 40.4 23.09
34 21.456 7.80 1.55332 71.7 23.77
35 * -36.369 (variable) 24.78
36 -40.925 2.00 1.53775 74.7 26.20
37 32.173 4.27 1.74950 35.3 29.83
38 137.272 30.21
Image plane ∞

Aspheric data 6th surface
K = 0.00000e + 000 A 4 = 3.22233e-006 A 6 = -1.79337e-009 A 8 = 7.50819e-012 A10 = -1.12107e-014 A12 = 1.47185e-017

24th page
K = 0.00000e + 000 A 4 = 1.23479e-005 A 6 = 1.93186e-008 A 8 = 3.32588e-011 A10 = 2.26724e-013 A12 = 1.41153e-016

32nd page
K = 0.00000e + 000 A 4 = 1.84053e-005 A 6 = 3.14491e-008 A 8 = -2.27450e-010 A10 = 2.44136e-012 A12 = -4.40951e-015

35th page
K = 0.00000e + 000 A 4 = 8.15654e-006 A 6 = -2.89246e-008 A 8 = 3.43569e-010 A10 = -1.49506e-012

Various data Zoom ratio 2.35
Wide angle Medium Tele focal length 28.84 44.14 67.90
F number 2.25 2.62 2.91
Half angle of view (degrees) 36.88 26.11 17.67
Image height 21.64 21.64 21.64
Total lens length 146.94 157.60 175.00
BF 20.75 28.77 34.64

d 5 3.87 16.60 34.15
d16 11.89 4.68 0.10
d26 5.24 1.96 0.10
d35 4.10 4.50 4.92

Entrance pupil position 48.58 72.24 119.94
Exit pupil position -38.86 -34.60 -32.57
Front principal point position 63.47 85.64 119.25
Rear principal point position -8.09 -15.36 -33.26

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 132.36 21.45 1.80 -12.03
2 6 -19.46 30.71 6.89 -17.92
3 17 50.53 17.70 -4.61 -16.09
4 27 38.05 24.96 3.18 -15.68
5 36 -82.75 6.27 0.97 -2.72

Single lens Data lens Start surface Focal length
1 1 -311.10
2 2 211.92
3 4 160.72
4 6 -42.81
5 8 -74.50
6 10 -29.04
7 11 39.61
8 13 155.73
9 15 -166.64
10 18 -214.70
11 19 38.64
12 21 94.21
13 23 -116.28
14 25 -216.45
15 27 47.80
16 29 47.26
17 31 -66.05
18 33 -23.70
19 34 25.62
20 36 -33.18
21 37 55.11

Focus wide angle infinity close (380mm)
d5 3.87 1.11
Middle infinity Close (380mm)
d5 16.60 13.10
Telephoto Infinity Close (380mm)
d5 34.15 29.08

L1 First lens group L2 Second lens group L3 Third lens group L4 Fourth lens group L5 Fifth lens group L6 Sixth lens group LR Rear group Ln Lens group on the most image side of rear group LR

Claims (9)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, and a rear group including a plurality of lens groups, which are arranged in order from the object side to the image side. A zoom lens with a variable interval,
Among the plurality of lens groups included in the rear group, a lens group Ln having a negative refractive power is disposed closest to the image side,
The focal length of the first lens group is f1, the focal length of the second lens group is f2, the combined focal length of the first lens group and the second lens group at the wide-angle end is f12, and the rear group at the wide-angle end is When the focal length is frw,
−8.0 <f1 / f2 <−5.5
−1.08 <f12 / frw <−0.95
A zoom lens satisfying the following conditional expression:   2. The zoom lens according to claim 1, wherein the second lens unit moves toward the object side during focusing from infinity to a short distance. When the back focus at the wide angle end is skdw and the focal length of the entire system at the wide angle end is fw,
0.50 <skdw / fw <0.90
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the lens group Ln is fn,
0.10 <f2 / fn <0.30
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.   The zoom lens according to any one of claims 1 to 4, wherein the lens group Ln includes one negative lens and one positive lens. When the focal length of the entire system at the telephoto end is ft and the length on the optical axis from the lens surface closest to the object side to the image plane at the telephoto end is Lt,
0.20 <ft / Lt <0.60
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.   The rear group includes a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power, which are arranged in order from the object side to the image side. The zoom lens according to any one of claims 1 to 6.   The rear group includes a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, a fifth lens group having a positive refractive power, and a negative refractive power, which are arranged in order from the object side to the image side. The zoom lens according to claim 1, comprising: a sixth lens group.   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.