JP5455998B2 - Zoom lens and imaging apparatus having the same - Google Patents

Description

  The present invention relates to a zoom lens and an imaging apparatus having the same, and is suitable for a photographing optical system such as a single-lens reflex camera, a digital still camera, a digital video camera, a TV camera, and a surveillance camera.

  Imaging apparatuses such as single-lens reflex cameras and video cameras are required to be able to perform autofocus (automatic focusing) at high speed and with high accuracy. As a zoom lens that facilitates high-speed autofocus, a so-called rear focus type zoom lens that performs focusing by moving a small and light lens group other than the first lens group on the object side is known (Patent Document 1). . In Patent Document 1, in a six-group zoom lens including first to sixth lens groups having negative, positive, negative, positive, negative, and positive refractive power, focusing is performed by a small and lightweight fifth lens group.

  On the other hand, recent single-lens reflex cameras are required to have a moving image shooting function and to be able to autofocus during moving image shooting. As an autofocus method when shooting a moving image, a high-frequency detection method (TV-AF method) is often used in which an in-focus state of a shooting optical system is evaluated by detecting a high-frequency component in an imaging signal.

  In an imaging apparatus using the TV-AF method, a focus lens group is vibrated at high speed in the optical axis direction (hereinafter referred to as “wobbling”) to detect a deviation direction from an in-focus state. After wobbling, a signal component in a specific frequency band of the image area is detected from the output signal of the image sensor, and the optimum position of the focus lens group that is in focus is calculated.

  Thereafter, the focus lens group is moved to the optimum position, and focusing is completed. In order to drive the focus lens group by wobbling, it is necessary to reduce the size and weight of the focus lens group. Among the lens groups constituting the zoom lens, zoom lenses that are focused using some small and lightweight lens groups are known (Patent Documents 2 and 3).

  Patent Document 2 discloses a zoom lens in which focusing is performed by a third lens group in a zoom lens including first to fifth lens groups having positive, negative, negative, positive, and positive refractive powers. Patent Document 3 discloses a zoom lens in which focusing is performed by a third lens group in a five-group zoom lens including first to fifth lens groups having positive, negative, positive, positive, and positive refractive powers.

JP 2009-199092 A JP 2009-251117 A JP 2009-251114 A

  In order to improve the autofocus speed, it is preferable to use a small and light lens group with a small number of lenses as the focus lens group. In order to reduce the amount of movement during focusing, a lens group with strong refractive power is preferably used as the focus lens group. Normally, when the focus lens group is configured with a small number of lenses, if the power (refractive power) of the focus lens group is increased, the residual aberration of the focus lens group increases, and the aberration fluctuation accompanying focusing increases. For this reason, the power of the focus lens group cannot be increased so much.

  On the other hand, when the power of the focus lens group is weakened, the amount of movement of the focus lens group during focusing increases. As a result, the space for moving the focus lens group becomes large, and it is impossible to secure a sufficient space for the zooming lens group to move. As a result, it becomes difficult to reduce the size of the entire system while maintaining high academic performance. In Patent Document 2, a third lens group having a negative refractive power is used as a focus lens group, and in Patent Document 3, a third lens group having a positive refractive power is used as a focus lens group.

  In these zoom lenses, as the power of the focus lens group is increased in order to reduce the amount of movement of the focus lens group, the negative power of the second lens group is increased in Patent Document 2 and the positive power of the fourth lens group in Patent Document 3. The power of will be weakened. Therefore, in Patent Document 2, when the lens group obtained by combining the second lens group and the third lens group is a lens group having a negative refractive power, the principal point position is larger than that of the second lens group having a negative refractive power. It shifts to the image side. Further, in Patent Document 3, when a lens group obtained by combining the third lens group and the fourth lens group is a lens group having a positive refractive power, the principal point position is larger than that of the third lens group having a positive refractive power. It will shift to the object side.

  As a result, it becomes difficult to appropriately set the power of each lens group in order to correct aberration fluctuations during zooming, and it tends to be difficult to achieve high performance and downsizing of the focus lens group. In general, in a zoom lens, in order to obtain high optical performance over the entire object distance, it is necessary to appropriately configure the zoom type and the focus lens group and the lens groups before and after the zoom lens to obtain high optical performance over a wide range of object distances. It becomes important.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a zoom lens that has high optical performance over the entire object distance and that can perform focusing at high speed, and an imaging apparatus having the same.

The zoom lens according to the present invention includes a lens unit Ln having a negative refractive power composed of two or less lenses that move during focusing and zooming, and a lens having a positive refractive power disposed adjacent to the object side of the lens unit Ln. A zoom lens having a lens unit Lp1 and a lens unit Lp2 having a positive refractive power disposed adjacent to the image side of the lens unit Ln, and the lens unit Lp1 and the lens unit Lp2 move integrally during zooming Because
The distance from the most object-side lens surface of the entire system to the image plane at the wide-angle end is Tlw, the distance from the lens-side lens surface of the lens unit Ln to the image plane at the wide-angle end is Dnw, and the back focus is at the wide-angle end. bfw, the maximum movement amount during focusing of the lens unit Ln at the telephoto end (positive when moving from the object side to the image side during focusing from infinity to the close range) is Mfnt, from the wide angle end to the telephoto end When the amount of change in the interval between the lens unit Ln and the lens unit Lp1 during zooming (the direction in which the interval increases is positive) is Mnz,
0.2 <(Dnw−bfw) / (Tlw−bfw) <0.8
0.3 <-Mnz / Mfnt <1.0
It satisfies the following conditional expression.
In addition, the zoom lens of the present invention includes a lens unit Ln having a negative refractive power composed of two or less lenses that move during focusing and zooming, and a positive refracting lens disposed adjacent to the object side of the lens unit Ln. A zoom lens having a power lens group Lp1 and a positive refractive power lens group Lp2 disposed adjacent to the image side of the lens group Ln, and the lens group Lp1 and the lens group Lp2 move during zooming Because
The distance from the most object-side lens surface of the entire system to the image plane at the wide-angle end is Tlw, the distance from the lens-side lens surface of the lens unit Ln to the image plane at the wide-angle end is Dnw, and the back focus is at the wide-angle end. bfw, the maximum movement amount during focusing of the lens unit Ln at the telephoto end (positive when moving from the object side to the image side during focusing from infinity to the close range) is Mfnt, from the wide angle end to the telephoto end An amount of change in the distance between the lens unit Ln and the lens unit Lp1 during zooming (the direction in which the interval increases is positive) is Mnz,
The rear principal point position of the combined lens group of the lens group Lp1, the lens group Ln, and the lens group Lp2 at the wide angle end is okw, the rear principal point position of the lens group Lp2 is okp2, and the focal length of the lens group Lp2 Is fp2,
0.2 <(Dnw−bfw) / (Tlw−bfw) <0.8
0.3 <-Mnz / Mfnt <1.0
| (Okw−okp2) / fp2 | <0.3
It satisfies the following conditional expression.
In addition, the zoom lens according to the present invention includes a lens unit Lp having a positive refractive power composed of two or less lenses that move during focusing and zooming, and a negative refraction arranged adjacent to the object side of the lens unit Lp. A lens unit Ln1 having a force and a lens unit Ln2 having a negative refractive power arranged adjacent to the image side of the lens unit Lp, and the lens unit Ln1 and the lens unit Ln2 move together during zooming. A zoom lens that
The distance from the most object-side lens surface of the entire system to the image plane at the wide-angle end is Tlw, the distance from the most image-side lens surface of the lens unit Ln2 to the image plane at the wide-angle end is Dn2w, and the back focus is at the wide-angle end. bfw, the maximum amount of movement during focusing of the lens unit Lp at the telephoto end (positive when moving from the object side to the image side during focusing from infinity to the closest distance) Mfpt, from the wide-angle end to the telephoto end When the amount of change in the distance between the lens unit Lp and the lens unit Ln2 during zooming (the direction in which the interval narrows is positive) is Mpz,
0.2 <(Dn2w−bfw) / (Tlw−bfw) <0.8
0.3 <-Mpz / Mfpt <1.0
It satisfies the following conditional expression.
In addition, the zoom lens according to the present invention includes a lens unit Lp having a positive refractive power composed of two or less lenses that move during focusing and zooming, and a negative refraction arranged adjacent to the object side of the lens unit Lp. A zoom lens having a power lens group Ln1 and a negative refractive power lens group Ln2 disposed adjacent to the image side of the lens group Lp, and the lens group Ln1 and the lens group Ln2 move during zooming Because
The distance from the most object-side lens surface of the entire system to the image plane at the wide-angle end is Tlw, the distance from the most image-side lens surface of the lens unit Ln2 to the image plane at the wide-angle end is Dn2w, and the back focus is at the wide-angle end. bfw, the maximum amount of movement during focusing of the lens unit Lp at the telephoto end (positive when moving from the object side to the image side during focusing from infinity to the closest distance) Mfpt, from the wide-angle end to the telephoto end The amount of change in the distance between the lens unit Lp and the lens unit Ln2 during zooming (the direction in which the interval narrows is positive) is expressed as Mpz,
The front principal point position of the combined lens group of the lens group Ln1, the lens group Lp, and the lens group Ln2 at the wide angle end is o1w, the front principal point position of the lens group Ln1 is o1n1, and the focal length of the lens group Ln1 is fn1. And when
0.2 <(Dn2w−bfw) / (Tlw−bfw) <0.8
0.3 <-Mpz / Mfpt <1.0
| (O1w−o1n1) / fn1 | <0.3
It satisfies the following conditional expression.

0.2 <(Dnw−bfw) / (Tlw−bfw) <0.8
0.3 <-Mnz / Mfnt <1.0
It satisfies the following conditional expression.

  According to the present invention, it is possible to obtain a zoom lens having high optical performance over the entire object distance and capable of performing focusing at high speed.

1 is a lens cross-sectional view at a wide angle end of a zoom lens according to a first embodiment of the present invention. (A), (B), (C), (D) The zoom lens according to Numerical Example 1 of the present invention is in focus at the wide-angle end and the telephoto end when focusing on an object at infinity, and at an object distance of 420 mm. Aberration diagram at wide-angle end and telephoto end Lens cross-sectional view at the wide-angle end of the zoom lens according to the second exemplary embodiment of the present invention. (A), (B), (C), (D) The zoom lens of Numerical Example 2 according to the present invention is focused on an object at infinity at the wide angle end and at the telephoto end, and when the object distance is 300 mm. Aberration diagram at wide-angle end and telephoto end Lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 3 of the present invention. (A), (B), (C), (D) In the zoom lens of Numerical Example 3 according to the present invention, when focusing on an object at infinity, the wide-angle end and the telephoto end, when focusing on an object distance of 390 mm Aberration diagram at wide-angle end and telephoto end Lens cross-sectional view at the wide-angle end of the zoom lens according to the fourth exemplary embodiment of the present invention. (A), (B), (C), (D) In the zoom lens of Numerical Example 4 according to the present invention, when focusing on an object at infinity, the wide-angle end and the telephoto end, when focusing on an object distance of 420 mm Aberration diagram at wide-angle end and telephoto end Lens cross-sectional view at the wide-angle end of the zoom lens according to the fifth exemplary embodiment of the present invention (A), (B), (C), (D) In the zoom lens of Numerical Example 5 according to the present invention, when focusing on an object at infinity, the wide-angle end and the telephoto end, when focusing on an object distance of 420 mm Aberration diagram at wide-angle end and telephoto end Schematic diagram of main parts of an imaging apparatus of the present invention

  Embodiments of the zoom lens of the present invention and an image pickup apparatus having the same will be described below. The zoom lens according to the present invention includes a lens unit Ln having a negative refractive power, which includes two or less lenses that move during focusing and zooming. Further, the lens unit Ln includes a positive refractive power lens unit Lp1 disposed adjacent to the object side of the lens unit Ln, and a positive refractive power lens unit Lp2 disposed adjacent to the image side of the lens unit Ln. The lens unit Lp1 and the lens unit Lp2 move during zooming.

  In addition, the zoom lens according to the present invention includes a lens unit Lp having a positive refractive power, which includes two or less lenses that move during focusing and zooming. Further, the lens unit Lp includes a lens unit Ln1 having a negative refractive power disposed adjacent to the object side of the lens unit Lp, and a lens unit Ln2 having a negative refractive power disposed adjacent to the image side of the lens unit Lp. The lens unit Ln1 and the lens unit Ln2 move during zooming.

  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. 2A, 2 </ b> B, 2 </ b> C, and 2 </ b> D are respectively a wide-angle end, a telephoto end (long focal length end), and a close distance when the zoom lens of Numerical Example 1 is focused on an infinite object. It is an aberration diagram at the wide-angle end and the telephoto end when focusing on an object (shooting distance: 420 mm). (Shooting distance of 420 mm is when the numerical values of numerical examples described later are expressed in mm. The same applies hereinafter).

  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, 4 </ b> B, 4 </ b> C, and 4 </ b> D are respectively the wide-angle end, the telephoto end, and the close-up object (shooting distance 300 mm) when the zoom lens of Numerical Example 2 is focused on an infinite object. FIG. 6 is an aberration diagram at the wide-angle end and the telephoto end when in focus.

  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. FIGS. 6A, 6B, 6C, and 6D are respectively the wide-angle end, the telephoto end, and the close-up object (shooting distance 390 mm) when the zoom lens of Numerical Example 3 is focused on an infinite object. FIG. 6 is an aberration diagram at the wide-angle end and the telephoto end when in focus.

  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, 8B, 8C, and 8D are respectively the wide-angle end, the telephoto end, and the close-up object (shooting distance 420 mm) when the zoom lens of Numerical Example 4 is focused on an infinite object. FIG. 6 is an aberration diagram at the wide-angle end and the telephoto end when in focus.

  FIG. 9 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 5 of the present invention. FIGS. 10A, 10B, 10C, and 10D are respectively the wide-angle end, the telephoto end, and the close-up object (shooting distance: 420 mm) when the zoom lens of Numerical Example 5 is focused on an infinite object. FIG. 6 is an aberration diagram at the wide-angle end and the telephoto end when in focus. FIG. 11 is a schematic diagram of a main part of a single-lens reflex camera (imaging device) including the zoom lens of the present invention.

  The zoom lens of each embodiment is a photographing lens system (optical system) used in an imaging apparatus such as a video camera, a digital camera, or a silver salt film camera. In the lens cross-sectional view, the left side is the 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. SP is an aperture stop. IP is an image plane, and when used as a photographing optical system for a video camera or a digital still camera, on the imaging surface of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor, Corresponds to the film surface.

  The arrows indicate the movement trajectory of each lens unit during zooming from the wide-angle end to the telephoto end. The spherical aberration diagram shows d-line (solid line) and g-line (broken line). In the astigmatism diagram, the broken line is the meridional image plane ΔM at the d line, and the solid line is the sagittal image plane ΔS at the d line. Moreover, the figure which shows distortion has shown the distortion in d line | wire. The lateral chromatic aberration is shown for the g-line. Fno is the F number, and ω is the half angle of view. In the following embodiments, the wide-angle end and the telephoto end refer to zoom positions when the zoom lens unit is positioned at both ends of a range in which the mechanism can move on the optical axis.

  In a normal zoom lens, the power (refractive power) of a focus lens group that moves by focusing is increased as much as possible, and the moving range during focusing is reduced, thereby reducing the size of the entire system. First, the difference between the zoom lens of the present invention and the zoom lenses disclosed in Patent Documents 1 to 3 will be described.

  In a zoom lens having a small number of lenses in the focus lens group, if the power of the focus lens group is increased too much, the residual aberration of the focus lens group becomes large, so that the aberration fluctuation due to the change in the object distance becomes remarkably large. For this reason, if both the reduction in size and weight of the focus lens group and the reduction in aberration fluctuation due to the change in object distance are achieved, the amount of focus movement increases, and the space for the zooming lens group to move decreases. For example, in the 6-group zoom lens of Patent Document 1, focusing is performed with a small lens and a fifth lens group having a negative refractive power.

  In Patent Document 1, the fourth lens group and the sixth lens group have positive power. By forming a composite lens group with positive refractive power from the fourth lens group to the sixth lens group, the principal point position of the composite lens group with positive refractive power is desired even if the power of the focus lens group is increased. It can be placed at the position.

  In Patent Document 1, in the synthetic lens group of the fourth lens group to the sixth lens group, the fifth lens group which is the focus lens group has a strong negative power, and a large movement space is secured. For this reason, the power becomes weaker than the fourth lens group having a positive refractive power of the four-group zoom lens including the lens groups having negative, positive, negative, and positive refractive power. For this reason, there is a tendency that the power distribution of the retrofocus is broken.

  Furthermore, because the lens group with strong negative refractive power is arranged at a position where the incident height of the off-axis chief ray close to the image surface is high, the off-axis ray is greatly bounced up and the axis of the positive lens on the image side The incident height of the outer principal ray changes, and the off-axis aberration tends to change as the object distance changes.

  Further, in the zoom lens of Patent Document 2, if the power of the third lens group that is the focus lens group is increased to suppress the focus movement amount, the negative refractive power obtained by combining the second lens group and the third lens group is reduced. The front principal point position of the lens group moves to the third lens group side. That is, it is synonymous with widening the distance between the first lens group and the second lens group as a variator at the wide-angle end in the four-group zoom including the lens groups having positive, negative, positive, and positive refractive powers. This is extremely disadvantageous for widening the angle.

  In Patent Document 2, the third lens group, which is a focus lens group, is moved during zooming so that the distance is reduced toward the second lens group at the wide-angle end and toward the fourth lens group at the telephoto end. Has doubled effect. However, it is necessary to secure the distance between the second lens group and the third lens group by the amount of movement of the focus lens group. For this reason, the movement of the second lens group toward the fourth lens group is limited, and the zooming effect as a variator is greatly deviated as compared with the above-described four-group zoom lens.

  In the zoom lens of Patent Document 3, the positive power (refractive power) of the fourth lens group is distributed to the third lens group side which is the focus lens group. Then, the principal point positions of the third lens group and the fourth lens group move to the third lens group side, and it is difficult to ensure a long back focus at the wide angle end. Further, during zooming from the wide-angle end to the telephoto end, the third lens group is zoomed by moving to the second lens group side. For this reason, the fourth lens group cannot be moved closer to the second lens group by the amount of movement of the focus lens group of the third lens group, and the zooming effect is lost as compared with the above-described four-group zoom lens. .

  On the other hand, in one aspect (Examples 1, 2, 4, and 5) of the zoom lens of the present invention, it is as follows. A positive power composite lens group (Lp1, Ln, Lp2) in which a negative power focus lens group Ln is sandwiched between a positive power lens group Lp1 and a positive power lens group Lp2 is positioned away from the image plane. Arranged.

  According to this, even if the power of the lens unit Ln is increased, the principal point position of the composite lens unit having a positive refractive power is not significantly changed. Therefore, the focus movement amount of the focus lens unit Ln is reduced, and the entire system is It becomes easy to reduce the size and weight. In addition, the lens unit Ln is disposed at a position somewhat away from the image side to avoid the incidence of the off-axis principal ray at a high incident height. As a result, the change in the incident height of the off-axis principal ray at the lens group Lp1 and the lens group Lp2 on both sides of the lens group Ln due to focusing is reduced, and the fluctuation in off-axis aberration due to the change in object distance is reduced.

  In addition, the lens group Ln can easily form an afocal relationship with either the lens group Lp1 or the lens group Lp2 on both sides of the lens group Ln, thereby reducing the change in the incident height of the axial ray due to focusing. As a result, variations in axial aberrations such as spherical aberration and axial chromatic aberration due to changes in the object distance are reduced.

  In the zoom lens according to the present invention, the lens unit Ln moves relative to the lens unit Lp1 in a direction of narrowing during focusing from an object at infinity to an object at a close distance. During zooming from the wide-angle end to the telephoto end, the lens unit Ln moves so as to spread oppositely with respect to the lens unit Lp1. As a result, a zooming effect is obtained, and a burden on each zooming lens group due to a space for moving the focus lens group is compensated. Thereby, while having a small and light focus mechanism, it has good optical performance in the entire zoom range and the entire focus range, and the entire system can be easily downsized.

In another aspect (Example 3) of the present invention, the positive and negative refractive powers of the relationship among the lens group Ln, the lens group Lp1, and the lens group Lp2 are reversed. In other words, the positive power focus lens group Lp, the negative refractive power lens group Ln1 and the negative refractive power lens group Ln2 adjacent to both sides thereof are arranged to obtain the same effect as described above. In the third embodiment, the lens unit Lp is moved relative to the lens unit Ln2 in a direction of narrowing during focusing from an object at infinity to a close object. During zooming from the wide-angle end to the telephoto end, the lens unit Lp moves so as to expand with respect to the lens unit Ln2.

  Next, the best mode in the zoom lens of the present embodiment will be described. First, the features of the zoom lenses of Examples 1, 2, 4, and 5 will be described. The first, second, fourth, and fifth embodiments include a lens unit Ln having a negative refractive power that includes two or less lenses that move during focusing and zooming. Further, the lens unit Ln includes a positive refractive power lens unit Lp1 disposed adjacent to the object side of the lens unit Ln, and a positive refractive power lens unit Lp2 disposed adjacent to the image side of the lens unit Ln. The lens unit Lp1 and the lens unit Lp2 move during zooming.

The distance from the lens surface closest to the object side of the entire system at the wide angle end to the image plane is defined as Tlw. The distance from the lens surface closest to the image side of the lens unit Ln at the wide angle end to the image surface is defined as Dnw. Let bfw be the back focus at the wide-angle end. Let Mfnt be the maximum amount of movement (focusing from the object side to the image side) during focusing of the lens unit Ln at the telephoto end. Lens unit Ln during zooming from the wide-angle end to the telephoto end
The amount of change in the distance between the lens unit Lp1 and the lens group Lp1 (the direction in which the distance increases is positive) is Mnz.

At this time,
0.2 <(Dnw−bfw) / (Tlw−bfw) <0.8 (1)
0.3 <-Mnz / Mfnt <1.0 (2)
The following conditional expression is satisfied.

  A lens unit Ln having a negative refractive power for focusing is sandwiched between a lens unit Lp1 having a positive power and a lens unit Lp2 having a positive power. Thereby, even if the power of the lens group Ln is increased, the principal point position of the combined lens group of the lens group Lp1, the lens group Ln, and the lens group Lp2 can be arranged at a desired position. Then, the power of the focusing lens group is increased and the amount of movement during focusing is reduced.

  The lens group Ln is arranged at a position satisfying the conditional expression (1) so that the change in the incident height of the off-axis chief rays to the lens groups Lp1 and Lp2 on both sides due to focusing is reduced. Changes in off-axis aberration due to changes in object distance are reduced. When deviating from the lower limit value of conditional expression (1), a lens group having a negative power is disposed near the image plane that requires a positive power at the wide-angle end. For this reason, the power arrangement of the retrofocus is destroyed, and it becomes difficult to achieve a wide angle of view and downsizing of the entire system.

  In addition, since the incident height of the off-axis chief ray is large on the image side, the off-axis light beam is bounced up with a strong negative power, and the fluctuation of off-axis aberration with the change of the object distance becomes large. If the upper limit value of conditional expression (1) is deviated, the lens unit Ln becomes too close to the object side, and the incident height of the off-axis principal ray increases in the direction opposite to the image plane side, resulting in a change in the object distance. As a result, the fluctuation of off-axis aberration becomes large. When the lens unit Ln is moved not only by focusing but also by zooming because of the conditional expression (2), the space in which the lens unit Ln moves by focusing can be effectively used for zooming, and the entire system can be easily downsized. Become.

  If the upper limit of the conditional expression (2) is deviated, an unnecessarily large space is required for the focus movement amount at the telephoto end of the lens unit Ln, and the entire system becomes large. When deviating from the lower limit of the conditional expression (2), the zooming effect by the lens unit Ln is reduced. By satisfying the conditional expressions (1) and (2), the lens group Ln has a small lens configuration of two or less lenses, but the focus movement amount is small and the zooming effect in zooming is increased, and further focusing is performed. It is easy to reduce aberration fluctuations due to the above. More preferably, the numerical values of conditional expressions (1) and (2) are set as follows.

0.25 <(Dnw−bfw) / (Tlw−bfw) <0.6 (1a)
0.35 <-Mnz / Mfnt <0.95 (2a)
In Examples 1, 2, 4, and 5, it is more preferable to satisfy one or more of the following conditions. The focal lengths of the lens group Ln, the lens group Lp1, and the lens group Lp2 are fn, fp1, and fp2, respectively. The effective beam diameters on the object side and the image side of the lens unit Ln are ea_nf and ea_nr, respectively. The effective beam diameters on the image side of the lens group Lp1 and the object side of the lens group Lp2 are ea_p1r and ea_p2f, respectively.

  The rear principal point position of the combined lens group of the lens group Lp1, the lens group Ln, and the lens group Lp2 at the wide angle end is okw, the rear principal point position of the lens group Lp2 is okp2, and the focal length of the lens group Lp2 is fp2. The lateral magnifications of the lens unit Ln at the wide-angle end and the telephoto end are βnw and βnt, respectively. At this time, it is preferable to satisfy one or more of the following conditional expressions.

0.4 <−fp1 / fn <2.5 (3)
0.4 <−fp2 / fn <2.5 (4)
0.7 <ea_p1r / ea_nf <1.4 (5)
0.7 <ea_p2f / ea_nr <1.4 (6)
| (Okw−okp2) / fp2 | <0.3 (7)
| Βnw | <1.0 (8)
| Βnt | <1.0 (9)
Conditional expressions (3) and (4) are used to satisfactorily correct the aberrations occurring in the lens unit Ln and the aberration fluctuations accompanying the change in the object distance between the lens unit Lp1 and the lens unit Lp2.

  When deviating from the upper limit values of the conditional expressions (3) and (4), the powers of the lens unit Lp1 and the lens unit Lp2 are weakened, and aberrations occurring in the lens unit Ln and aberration variations accompanying changes in the object distance are excessive. As a result, the optical performance deteriorates. When deviating from the lower limit values of the conditional expressions (3) and (4), the power of the lens unit Ln is too weak, so that the amount of focus movement increases and the entire system becomes larger.

  Conditional expressions (5) and (6) relate to the effective beam diameters of the lens unit Ln, the lens unit Lp1, and the lens unit Lp2. Conditional expressions (5) and (6) define the effective diameter ratio between the lens unit Ln and the lens unit Lp1 and the lens unit Lp2, respectively. By making the values of conditional expressions (5) and (6) close to 1, the change in the incident height of the off-axis principal ray is reduced, and the off-axis aberrations such as field curvature and lateral chromatic aberration due to the change in the object distance are reduced. The fluctuation is reduced.

  When deviating from the upper limit values of the conditional expressions (5) and (6), the effective diameters of the lens group Lp1 and the lens group Lp2 are too large for the lens group Ln, respectively, and deviating from the lower limit value, the lens group Lp1, On the contrary, the effective diameter of the lens unit Lp2 is too small. In either case, since the change in the incident height of the off-axis chief ray on the lens unit Ln becomes large, the variation in off-axis aberration accompanying the change in the object distance becomes large.

  Conditional expression (7) indicates that the rear principal point position of the composite lens group at the wide-angle end made up of the lens group Lp1, the lens group Ln, and the lens group Lp2 is close to the rear principal point position of the lens group Lp2, thereby performing aberrations during zooming. This is to correct the above. If the upper limit of conditional expression (7) is exceeded and the rear principal point position okw deviates to the larger side, the power of the lens unit Lp1 is weak and the power of the lens unit Ln is too strong. It becomes.

  When the upper limit of conditional expression (7) is exceeded and the rear principal point position okw deviates to a smaller side, the principal point position of the composite lens unit having a positive refractive power is too far from the image side, and the retrofocus power The arrangement will collapse and the entire system will become larger.

  Conditional expression (8) relates to the lateral magnification at the wide-angle end of the lens unit Ln. By satisfying the conditional expression (8), the distance between the lens unit Lp1 and the lens unit Ln is made afocal, and variations in axial aberrations such as spherical aberration and axial chromatic aberration due to changes in the object distance are reduced. . When deviating from the conditional expression (8), the afocal between the lens units Lp1 and Ln is lost, and the variation of the axial aberration due to the change in the object distance increases.

  Conditional expression (9) is for setting the lateral magnification appropriately not only at the wide-angle end of the lens unit Ln but also at the telephoto end, as in conditional expression (8). By satisfying conditional expression (9), at the telephoto end as well as at the wide-angle end, the lens groups of the lens unit Lp1 and the lens unit Ln are brought close to afocal, and the variation of the axial aberration due to the change in the object distance is observed. It is small. More preferably, the numerical ranges of the conditional expressions (3) to (9) are set as follows.

0.7 <−fp1 / fn <2.0 (3a)
0.5 <−fp2 / fn <1.6 (4a)
0.83 <ea_p1r / ea_nf <1.2 (5a)
0.83 <ea_p2f / ea_nr <1.2 (6a)
| (Okw−okp2) / fp2 | <0.2 (7a)
| Βnw | <0.4 (8a)
| Βnt | <0.5 (9a)
In the first, second, fourth, and fifth embodiments, when the lens unit Lp1 and the lens unit Lp2 are moved together during zooming, the relative eccentricity of each lens unit can be suppressed, manufacturing errors can be reduced, and the mechanical structure can be simplified. Therefore, it is preferable.

  Next, features of the zoom lens according to Embodiment 3 will be described. The zoom lens according to the third exemplary embodiment includes the lens unit Lp having a positive refractive power, which includes two or less lenses that move during focusing and zooming. Further, the lens unit Lp includes a lens unit Ln1 having a negative refractive power disposed adjacent to the object side of the lens unit Lp, and a lens unit Ln2 having a negative refractive power disposed adjacent to the image side of the lens unit Lp. The lens unit Ln1 and the lens unit Ln2 move during zooming.

  Let Tlw be the distance from the lens surface closest to the object side of the entire system to the image plane at the wide-angle end. The distance from the lens surface closest to the image side of the lens unit Ln2 to the image surface at the wide angle end is defined as Dn2w. Let bfw be the back focus at the wide-angle end. Let Mfpt be the maximum amount of movement (focusing from the object side to the image side) during focusing of the lens unit Lp at the telephoto end. The amount of change in the distance between the lens unit Lp and the lens unit Ln2 during zooming from the wide-angle end to the telephoto end (the direction in which the interval narrows is positive) is defined as Mpz.

At this time,
0.2 <(Dn2w−bfw) / (Tlw−bfw) <0.8 (10)
0.3 <-Mpz / Mfpt <1.0 (11)
The following conditional expression is satisfied.

  A lens unit Lp having a positive refractive power for focusing is sandwiched between a lens unit Ln1 having a negative power and a lens unit Ln2 having a negative power. Thereby, even if the power of the lens group Lp is increased, the principal point position of the combined lens group of the lens group Ln1, the lens group Lp, and the lens group Ln2 can be arranged at a desired position. Then, the power of the focusing lens group is increased and the amount of movement during focusing is reduced.

  The lens group Lp is arranged at a position satisfying the conditional expression (10) so that the change in the incident height of the off-axis chief rays to the lens groups Ln1 and Ln2 on both sides due to focusing is reduced. The fluctuation of off-axis aberration due to the change of the object distance is reduced. When deviating from the lower limit value of conditional expression (10), a lens group having a strong negative power is arranged near the image plane that requires a strong positive power at the wide-angle end. For this reason, the power arrangement of the retrofocus is destroyed, and it becomes difficult to achieve a wide angle of view and downsizing of the entire system.

  In addition, since the incident height of the off-axis chief ray is large on the image side, the off-axis light beam is bounced up with a strong negative power, and the fluctuation of off-axis aberration with the change of the object distance becomes large. If the upper limit of conditional expression (10) is deviated, the lens unit Ln2 becomes too close to the object side, and the incident height of the off-axis principal ray increases in the direction opposite to the image plane side, resulting in a change in the object distance. The fluctuation of the off-axis aberration is increased.

  When the lens unit Lp moves not only in focusing but also in zooming because of the conditional expression (11), the space in which the lens unit Lp moves with focus can be used effectively for zooming, and the entire system can be easily downsized. Become. If the upper limit of conditional expression (11) is deviated, more space is required than is necessary for the amount of focus movement at the telephoto end of the lens unit Lp, and the entire system becomes larger. When deviating from the lower limit of the conditional expression (11), the zooming effect of the lens unit Lp is reduced.

  By satisfying the conditional expressions (10) and (11), the lens unit Lp has a small lens configuration of two or less lenses, but the focus movement amount is small and the zooming effect in zooming is large, and further focusing is performed. It is easy to reduce aberration fluctuations due to the above. More preferably, the numerical ranges of conditional expressions (10) and (11) are set as follows.

0.3 <(Dn2w−bfw) / (Tlw−bfw) <0.7 (10a)
0.35 <-Mpz / Mfpt <0.95 (11a)
More preferably, one or more of the following conditions should be satisfied. The focal lengths of the lens unit Lp, the lens unit Ln1, and the lens unit Ln2 are fp, fn1, and fn2, respectively. The effective beam diameters on the object side and the image side of the lens unit Lp are ea_pf and ea_pr, respectively. The effective beam diameters on the image side of the lens group Ln1 and on the object side of the lens group Ln2 are ea_n1r and ea_n2f, respectively.

  A front principal point position of the combined lens unit of the lens unit Ln1, the lens unit Lp, and the lens unit Ln2 at the wide angle end is defined as o1w. The front principal point position of the lens unit Ln1 is set to o1n1, and the focal length of the lens unit Ln1 is set to fn1. The lateral magnifications of the lens unit Ln2 at the wide-angle end and the telephoto end are βn2w and βn2t, respectively. At this time, it is preferable to satisfy one or more of the following conditional expressions.

0.3 <−fn1 / fp <2.5 (12)
0.3 <−fn2 / fp <2.5 (13)
0.7 <ea_n1r / ea_pf <1.4 (14)
0.7 <ea_n2f / ea_pr <1.4 (15)
| (O1w−o1n1) / fn1 | <0.3 (16)
| Βn2w | <1.0 (17)
| Βn2t | <1.0 (18)
Conditional expressions (12) and (13) are used to satisfactorily correct the aberrations occurring in the lens unit Lp and the aberration fluctuations accompanying changes in the object distance in the lens unit Ln1 and the lens unit Ln2.

  When deviating from the upper limit values of the conditional expressions (12) and (13), the powers of the lens unit Ln1 and the lens unit Ln2 are weakened, and each aberration generated in the lens unit Lp and aberration fluctuations accompanying changes in the object distance are excessive. As a result, the optical performance deteriorates. When deviating from the lower limit values of the conditional expressions (12) and (13), the power of the lens unit Lp is too weak, so that the amount of focus movement increases and the entire system becomes larger.

  Conditional expressions (14) and (15) relate to the effective beam diameters of the lens unit Lp, the lens unit Ln1, and the lens unit Ln2. Conditional expressions (14) and (15) define the effective diameter ratio between the lens unit Lp and the lens unit Ln1 and the lens unit Ln2, respectively. By making the values of conditional expressions (14) and (15) close to 1, the change in the incident height of the off-axis principal ray is reduced, and the off-axis aberrations such as field curvature and lateral chromatic aberration accompanying the change in the object distance are reduced. The fluctuation is reduced.

  When deviating from the upper limit values of the conditional expressions (14) and (15), the effective diameters of the lens group Ln1 and the lens group Ln2 are too large for the lens group Lp, respectively, and when deviating from the lower limit value, the lens group Ln1, On the contrary, the effective diameter of the lens unit Ln2 is too small. In either case, since the change in the incident height of the off-axis chief ray on the lens unit Lp becomes large, the variation in off-axis aberration accompanying the change in the object distance becomes large.

  Conditional expression (16) favorably corrects aberrations during zooming by bringing the front principal point position of the composite lens group at the wide-angle end of the lens group Ln1, lens group Lp, and lens group Ln2 closer to the front principal point position of the lens group Ln1. Is to do. If the upper limit value of conditional expression (16) deviates to the side where the front principal point position o1w becomes smaller, the power of the lens unit Ln2 is weak, and conversely, the power of the lens unit Lp is too strong. come.

  If the upper limit value of conditional expression (16) deviates to the side where the front principal point position o1w becomes larger, the principal point position of the composite lens unit having negative refractive power is too close to the image side, and the power arrangement of the retrofocus is destroyed. The whole system becomes larger.

  Conditional expression (17) relates to the lateral magnification at the wide angle end of the lens unit Ln2. By satisfying conditional expression (17), the distance between the lens unit Lp and the lens unit Ln2 is made afocal, and variations in axial aberrations such as spherical aberration and axial chromatic aberration due to changes in the object distance are reduced. . When deviating from the conditional expression (17), the afocal between the lens units Lp and Ln2 is lost, and the variation of the axial aberration due to the change of the object distance becomes large.

  Conditional expression (18) is for setting the lateral magnification appropriately not only at the wide-angle end of the lens unit Ln2 but also at the telephoto end, as in conditional expression (17). By satisfying conditional expression (18), at the telephoto end as well as at the wide angle end, the lens groups of the lens unit Lp and the lens unit Ln2 are brought close to afocal, and the variation of the axial aberration due to the change in the object distance is observed. It is small. More preferably, the numerical ranges of conditional expressions (10) to (18) are set as follows.

0.35 <-fn1 / fp <1.6 (12a)
0.6 <−fn2 / fp <2.0 (13a)
0.83 <ea_n1r / ea_pf <1.2 (14a)
0.83 <ea_n2f / ea_pr <1.2 (15a)
| (O1w−o1n1) / fn1 | <0.2 (16a)
| Βn2w | <0.4 (17a)
| Βnt | <0.4 (18a)
In the third embodiment, it is preferable to move the lens unit Ln1 and the lens unit Ln2 together during zooming because relative decentering of each lens unit can be suppressed, manufacturing errors can be reduced, and the mechanical structure can be simplified.

  As described above, according to each embodiment, it is possible to obtain a zoom lens that has a small and light focus mechanism and has good optical performance in the entire zoom range and the entire focus range, and the entire system is small and light. it can.

  Next, each example will be described. The first exemplary embodiment includes a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, a third lens unit L3 having a positive refractive power, a fourth lens unit L4 having a negative refractive power, and an aperture. It includes a fifth lens unit L5 having a positive refractive power including the stop SP and a sixth lens unit L6 having a positive refractive power. During zooming from the wide-angle end to the telephoto end, the first lens unit L1 and the third lens unit L3 to the sixth lens unit L6 move to the object side, and the second lens unit L2 draws a convex locus on the image side. A moving zoom lens.

  The first embodiment is a positive lead type six-group zoom lens having a zoom ratio of 7.02. During focusing from an infinitely distant object to a close object, the fourth lens unit L4 moves to the object side as indicated by an arrow Focus. The fourth lens group L4 corresponds to the lens group Ln, the third lens group L3 corresponds to the lens group Lp1, and the fifth lens group L5 corresponds to the lens group Lp2.

  In the first embodiment, the focusing lens group Ln has a single lens configuration and achieves a reduction in size and weight. The lens units Lp1 and Lp2 having positive refractive power are arranged adjacent to both sides of the lens unit Ln. As a result, even if the power of the lens unit Ln is increased, the principal point positions of the positive composite lens units of the lens unit Lp1, the lens unit Ln, and the lens unit Lp2 can be appropriately arranged during zooming. The miniaturization and high performance of the

  Specifically, the principal point of the composite lens unit having a positive refractive power is disposed at a position satisfying conditional expression (7). Further, the negative lens unit Ln is disposed at a position satisfying conditional expression (1) away from the image plane side. As a result, a sufficient positive power near the image plane can be obtained, and a wide angle of view and a reduction in the size of the entire system can be effectively achieved by forming a retrofocus type power arrangement well. In addition, the fluctuation of the incident height of the off-axis principal ray in the combined lens group of the lens unit Lp1, the lens unit Ln, and the lens unit Lp2 due to the change in the object distance is suppressed, and good optical performance is obtained in the entire focus range. Yes.

  Next, the lens unit Ln moves in a direction (object side) in which the distance from the lens unit Lp1 is narrowed during focusing. On the contrary, in zooming from the wide-angle end to the telephoto end, the lens unit Lp1 moves so as to widen the distance. And by satisfying conditional expression (2), the moving space for focusing is effectively used for zooming.

  Next, the relationship between the power of the lens group Ln, the lens group Lp1, and the lens group Lp2 satisfies the conditional expressions (3) and (4), and the lens group Lp1, the lens group Ln, and the lens group according to the change in the object distance. The fluctuation of the incident height of the axial ray within the Lp2 synthetic lens group is reduced. In addition, the lateral magnification in the lens unit Ln satisfies the conditional expressions (8) and (9), and the object between the lens unit Ln and the lens unit Lp1 is afocal at both the wide-angle end and the telephoto end. The variation of the incident height of the on-axis light beam due to the change in distance is further reduced.

  In addition, since the relationship between the effective diameters of the lens unit Ln, the lens unit Lp1, and the lens unit Lp2 satisfies (5) and (6), the variation in the incident height of the off-axis ray accompanying the change in the object distance is reduced. Yes. Further, the lens group Lp1 and the lens group Lp2 are integrally moved during zooming, and the mechanical configuration is simplified so that manufacturing errors in the combined lens group of the lens group Lp1, the lens group Ln, and the lens group Lp2 are reduced. Yes.

  In the second embodiment, in order from the object side to the image side, a first lens unit L1 having a negative refractive power, a second lens unit L2 having a positive refractive power, a third lens unit L3 having a negative refractive power, and an aperture stop SP are provided. A fourth lens unit L4 having a positive refractive power and a fifth lens unit L5 having a positive refractive power are included. During zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves along a locus that is convex toward the image side, and the second lens unit L2 to the fifth lens unit L5 are zoom lenses that move toward the object side. .

  Example 2 is a negative lead type 5-group zoom lens having a zoom ratio of 2.42. When focusing from an infinitely distant object to a close object, the third lens unit L3 moves to the object side as indicated by an arrow Focus. The third lens group L3 corresponds to the lens group Ln, the second lens group L2 corresponds to the lens group Lp1, and the fourth lens group L4 corresponds to the lens group Lp2. In the second embodiment, the focusing lens group Ln has a single lens configuration and achieves a reduction in size and weight. The optical functions of the lens group Ln, the lens group Lp1, and the lens group Lp2 are the same as those in the first embodiment.

  The third exemplary embodiment includes a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, a third lens unit L3 having a positive refractive power, a fourth lens unit L4 having a negative refractive power, and an aperture. It includes a fifth lens unit L5 having a positive refractive power including the stop SP and a sixth lens unit L6 having a positive refractive power. During zooming from the wide-angle end to the telephoto end, the first, third, fifth, and sixth lens groups L1, L3, L5, and L6 move to the object side, and the second and fourth lens groups L2 and L4 move to the image side. The zoom lens moves in a convex locus.

  Example 3 is a positive lead type six-group zoom lens with a zoom ratio of 7.05. The third lens unit L3 moves to the image side during focusing from an object at infinity to a close object. The third lens group L3 corresponds to the lens group Lp, the second lens group L2 corresponds to the lens group Ln1, and the fourth lens group L4 corresponds to the lens group Ln2.

  In the third embodiment, the focusing lens unit Lp has a single lens configuration and achieves a reduction in size and weight. Neighboring lens groups Ln1 and Ln2 are arranged adjacent to both sides of the lens group Lp. Accordingly, even when the power of the lens unit Lp is increased, the principal point positions of the negative composite lens units of the lens unit Ln1, the lens unit Lp, and the lens unit Ln2 can be appropriately arranged during zooming, The miniaturization and high performance of the

  Specifically, the principal point of the composite lens group having negative refractive power is arranged at a position satisfying conditional expression (16). Further, the lens unit Ln2 is disposed at a position satisfying conditional expression (10) away from the image plane side. As a result, a sufficient positive power near the image plane can be obtained, and a wide angle of view and a reduction in the size of the entire system can be effectively achieved by forming a retrofocus type power arrangement well. In addition, the fluctuation of the incident height of the off-axis principal ray in the combined lens group of the lens unit Ln1, the lens unit Lp, and the lens unit Ln2 due to the change of the object distance is suppressed, and good optical performance is obtained in the entire focus range. Yes.

  Next, the lens unit Lp moves in the direction of narrowing the interval with the lens unit Ln2 during focusing, and conversely, in zooming from the wide angle end to the telephoto end, it moves in the direction of increasing the interval with the lens unit Ln2. And by satisfying conditional expression (11), the moving space for focusing is effectively used for zooming. Next, the relationship between the powers of the lens unit Lp, the lens unit Ln1, and the lens unit Ln2 satisfies the conditional expressions (12) and (13), and the on-axis rays in the composite lens unit accompanying the change in the object distance. The fluctuation of the incident height is reduced.

  In addition, the lateral magnification in the lens unit Ln2 satisfies the conditional expressions (17) and (18), and the object between the lens unit Lp and the lens unit Ln2 is afocal at both the wide-angle end and the telephoto end. The variation of the incident height of the on-axis light beam due to the change in distance is further reduced. In addition, when the relationship between the effective diameters of the lens unit Lp, the lens unit Ln1, and the lens unit Ln2 satisfies (14) and (15), the variation in the incident height of the off-axis ray due to the change in the object distance is reduced. Yes.

  Further, the lens group Ln1 and the lens group Ln2 are moved during zooming, and the mechanical configuration is simplified so as to reduce manufacturing errors in the combined lens group of the lens group Ln1, the lens group Lp, and the lens group Ln2.

  In Example 4, in order from the object side to the image side, a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, a third lens unit L3 having a positive refractive power, and a negative refractive power. The fourth lens unit L4 and the fifth lens unit L5 having a positive refractive power including the aperture stop SP. During zooming from the wide-angle end to the telephoto end, the first lens unit L1 and the third lens unit L3 to the fifth lens unit L5 move to the object side, and the second lens unit L2 draws a convex locus on the image side. A moving zoom lens.

  Example 4 is a positive lead type 5-group zoom lens with a zoom ratio of 5.59. During focusing from an infinitely distant object to a close object, the fourth lens unit L4 moves to the object side as indicated by an arrow Focus. The fourth lens group L4 corresponds to the lens group Ln, the third lens group L3 corresponds to the lens group Lp1, and the fifth lens group L5 corresponds to the lens group Lp2. In the fourth embodiment, the negative lens group Ln for focusing has a single lens configuration and achieves a reduction in size and weight. The optical functions of the lens unit Ln and the positive lens units Lp1 and Lp2 are the same as those in the first embodiment.

  The fifth embodiment includes a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, a third lens unit L3 having a positive refractive power, a fourth lens unit L4 having a negative refractive power, and an aperture. It includes a fifth lens unit L5 having a positive refractive power including the stop SP and a sixth lens unit L6 having a positive refractive power. During zooming from the wide-angle end to the telephoto end, the first lens unit L1 and the third lens unit L3 to the sixth lens unit L6 move to the object side, and the second lens unit L2 draws a convex locus on the image side. A moving zoom lens. Example 5 is a positive lead type 6-group zoom lens with a zoom ratio of 6.45.

  During focusing from an object at infinity to a close object, the fourth lens unit L4 moves to the object side as indicated by an arrow Focus. The fourth lens group L4 corresponds to the lens group Ln, the third lens group L3 corresponds to the lens group Lp1, and the fifth lens group L5 corresponds to the lens group Lp2. In the fifth embodiment, the focusing lens group Ln has a two-lens configuration and achieves a reduction in size and weight. The optical functions of the lens unit Ln and the positive lens units Lp1 and Lp2 are the same as those in the first embodiment.

  As mentioned above, although the preferable Example of this invention was described, it cannot be overemphasized that this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary. In addition, the lens group referred to in each embodiment refers to a front surface of the optical system or a surface in which the distance from the lens adjacent to the front changes by zooming or focusing, and a lens adjacent to the rear surface or the rear of the optical system. To the surface where the interval of changes by zooming or focusing.

  The zoom lens of the present invention can be variously applied to, for example, an imaging device, an image projection device, and other optical devices.

  Next, an embodiment in which the zoom lens described in Embodiments 1 to 5 is applied to an imaging apparatus will be described with reference to FIG. The imaging apparatus of the present invention is an interchangeable lens apparatus including a zoom lens, and is detachably connected to the interchangeable lens apparatus via a camera mount unit, and receives an optical image formed by the zoom lens and converts it into an electrical image signal. And a camera body including an image pickup device.

  FIG. 11 is a schematic diagram of a main part of a single-lens reflex camera. In FIG. 11, reference numeral 10 denotes a photographing lens having the zoom lens 1 of the first to fifth embodiments. The zoom lens 1 is held by a lens barrel 2 that is a holding member. Reference numeral 20 denotes a camera body, which includes a quick return mirror 3 that reflects the light beam from the photographing lens 10 upward, and a focusing screen 4 that is disposed at an image forming position of the photographing lens 10. Further, it is constituted by a penta roof prism 5 for converting an inverted image formed on the focusing screen 4 into an erect image, an eyepiece 6 for observing the erect image, and the like.

  Reference numeral 7 denotes a photosensitive surface, on which a solid-state imaging device (photoelectric conversion device) or a silver salt film that receives an image formed by a zoom lens such as a CCD sensor or a CMOS sensor is arranged. At the time of photographing, the quick return mirror 3 is retracted from the optical path, and an image is formed on the photosensitive surface 7 by the photographing lens 10. The zoom lens of each embodiment can be similarly applied to a mirrorless single-lens reflex camera without a quick return mirror.

  Numerical examples 1 to 5 corresponding to the first to fifth examples are shown below. In each numerical example, i indicates the order of the surfaces from the object side. In numerical examples, ri is the radius of curvature of the i-th lens surface in order from the object side, di is the i-th lens thickness and air spacing in order from the object side, and ndi and νdi are the i-th lens in order from the object side. The refractive index and Abbe number of the material. BF is a back focus. The aspherical shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the light traveling direction is positive, r is the paraxial radius of curvature, and each aspheric coefficient is A4, A6, A8, A10, A12. When

Shall be given in In each aspheric coefficient, “e−x” means “10 ^−x ”. In addition to specifications such as focal length and F-number, the angle of view is the half angle of view of the entire system, the image height is the maximum image height that determines the half angle of view, and the total lens length is the distance from the first lens surface to the image surface. is there. The back focus BF indicates the length from the final lens surface to the image plane. Each lens group data represents the focal length, the length on the optical axis, the front principal point position, and the rear principal point position of each lens group. Further, the portion where the interval d between the optical surfaces is (variable) changes during zooming, and the surface interval corresponding to the focal length is shown in the separate table.

  Surface number 1 is a dummy surface used in the design. The dummy surface does not constitute a zoom lens. Table 1 shows the calculation results of the conditional expressions based on the lens data of Numerical Examples 1 to 5 described below.

(Numerical example 1)

Unit mm

Surface data surface number rd nd νd Effective diameter
1 ∞ 1.50 60.02
2 111.698 2.00 1.84666 23.9 52.66
3 55.370 7.65 1.49700 81.5 50.01
4 3384.032 0.15 49.68
5 53.774 6.23 1.66672 48.3 48.11
6 295.614 (variable) 47.31
7 152.605 1.45 1.91082 35.3 30.90
8 15.649 7.30 23.59
9 -48.289 1.20 1.77250 49.6 23.35
10 64.582 0.29 23.25
11 31.507 6.72 1.84666 23.8 23.64
12 -34.468 1.10 1.77250 49.6 23.08
13 145.612 (variable) 22.11
14 87.716 1.95 1.78472 25.7 14.57
15 -58.571 (variable) 14.57
16 -34.608 0.70 1.90366 31.3 14.18
17 579.002 (variable) 14.45
18 22.161 4.00 1.60311 60.6 16.08
19 -55.101 1.61 15.76
20 (Aperture) ∞ 3.30 14.77
21 30.440 4.91 1.60311 60.6 13.77
22 -17.452 0.75 1.84666 23.8 12.84
23 -494.346 3.07 12.52
24 -24.672 0.70 1.80000 29.8 11.77
25 13.389 2.54 1.84666 23.8 11.95
26 53.386 (variable) 12.01
27 * 94.305 3.99 1.68893 31.1 15.40
28 -27.400 16.47

Aspheric data 27th surface
K = 0.00000e + 000 A 4 = -2.62044e-005 A 6 = 2.02686e-009 A 8 = -4.13481e-011 A10 = -7.33645e-012 A12 = 7.19025e-014

Various data Zoom ratio 7.02

Wide angle Medium telephoto focal length 18.60 51.00 130.50
F number 3.48 4.84 5.88
Angle of view 36.29 14.99 5.98
Image height 13.66 13.66 13.66
Total lens length 140.52 160.20 190.00
BF 35.60 56.40 71.56

d 6 0.90 21.92 42.41
d13 26.18 6.70 1.50
d15 2.83 4.19 8.87
d17 7.09 5.73 1.05
d26 4.80 2.15 1.50

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 88.69 17.53 5.86 -5.78
2 7 -17.44 18.06 1.34 -11.69
3 14 45.02 1.95 0.66 -0.44
4 16 -36.12 0.70 0.02 -0.35
5 18 37.72 20.89 -21.54 -23.56
6 27 31.24 3.99 1.85 -0.54

(Numerical example 2)

Unit mm

Surface data surface number rd nd νd Effective diameter
1 ∞ 1.50 50.25
2 57.445 4.55 1.60311 60.6 41.82
3 219.037 0.50 39.96
4 36.443 1.45 1.83481 42.7 32.01
5 14.175 7.58 24.39
6 -619.065 1.20 1.77250 49.6 24.02
7 25.691 3.98 22.57
8 23.423 4.90 1.80518 25.4 22.94
9 200.752 1.10 1.80400 46.6 21.98
10 41.851 (variable) 21.04
11 -229.585 1.73 1.60311 60.6 13.06
12 -34.650 (variable) 13.21
13 -32.574 0.70 1.83400 37.2 13.12
14 -276.813 (variable) 13.34
15 28.173 3.13 1.63854 55.4 13.98
16 -53.605 1.04 13.99
17 (Aperture) ∞ 3.30 13.66
18 22.851 4.24 1.60311 60.6 13.49
19 -21.794 0.75 1.85026 32.3 12.87
20 -162.935 2.71 12.64
21 -40.305 0.70 1.74950 35.3 11.89
22 15.099 1.99 1.84666 23.8 11.81
23 25.535 (variable) 11.71
24 * 103.888 3.69 1.58313 59.4 14.34
25 -22.955 15.38

Aspheric data 24th surface
K = 0.00000e + 000 A 4 = -2.73707e-005 A 6 = -2.63537e-008 A 8 = 1.01748e-009 A10 = -1.40793e-011 A12 = -1.53554e-022

Various data Zoom ratio 2.42

Wide angle Medium Telephoto focal length 18.59 24.00 45.00
F number 3.59 4.06 5.95
Angle of view 36.31 29.65 16.89
Image height 13.66 13.66 13.66
Total lens length 118.97 117.26 127.42
BF 35.70 42.77 68.38

d10 23.35 15.60 2.10
d12 3.02 3.73 3.73
d14 1.88 1.16 1.17
d23 4.27 3.24 1.30

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -24.19 26.76 10.07 -10.77
2 11 67.44 1.73 1.26 0.19
3 13 -44.32 0.70 -0.05 -0.43
4 15 32.81 17.87 -13.46 -18.43
5 24 32.59 3.69 1.93 -0.43

(Numerical Example 3)

Unit mm

Surface data surface number rd nd νd Effective diameter
1 ∞ 1.50 59.50
2 136.714 1.90 1.84666 23.8 57.10
3 61.723 8.41 1.49700 81.5 54.57
4 -712.008 0.15 53.99
5 55.292 6.38 1.77250 49.6 51.49
6 218.242 (variable) 50.63
7 239.607 1.45 1.83481 42.7 30.66
8 14.432 7.38 22.80
9 -44.308 1.20 1.77250 49.6 22.69
10 71.255 0.15 22.79
11 30.488 5.77 1.84666 23.8 23.27
12 -48.245 1.10 1.83481 42.7 22.82
13 105.391 (variable) 22.15
14 114.988 2.94 1.83481 42.7 20.08
15 -38.856 (variable) 19.84
16 -42.545 0.70 1.80610 40.9 18.21
17 104.476 (variable) 17.74
18 20.554 3.70 1.53996 59.5 15.88
19 -92.362 1.18 15.50
20 (Aperture) ∞ 3.30 14.91
21 25.900 4.34 1.48749 70.2 14.11
22 -21.604 0.75 1.84666 23.8 13.39
23 -213.343 3.09 13.20
24 -46.278 0.70 1.76200 40.1 12.48
25 19.900 2.11 1.84666 23.8 12.47
26 52.323 (variable) 12.42
27 * 114.978 3.14 1.58313 59.4 15.12
28 -31.788 15.82

Aspheric data 27th surface
K = 0.00000e + 000 A 4 = -3.32763e-005 A 6 = 7.41615e-008 A 8 = -3.14564e-009 A10 = 4.14055e-011 A12 = -2.46577e-013

Various data Zoom ratio 7.05

Wide angle Medium Telephoto focal length 18.59 50.00 131.00
F number 3.51 4.71 5.88
Angle of view 36.31 15.28 5.95
Image height 13.66 13.66 13.66
Total lens length 138.97 159.44 187.88
BF 35.70 55.36 72.74

d 6 1.00 22.00 40.44
d13 7.85 6.05 1.52
d15 2.91 4.71 9.25
d17 23.69 7.04 1.05
d26 6.47 2.94 1.55

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 84.91 18.34 6.47 -5.44
2 7 -15.06 17.05 2.01 -10.00
3 14 35.09 2.94 1.21 -0.41
4 16 -37.43 0.70 0.11 -0.27
5 18 41.45 19.18 -15.02 -21.67
6 27 43.05 3.14 1.56 -0.43

(Numerical example 4)

Unit mm

Surface data surface number rd nd νd Effective diameter
1 ∞ 1.50 64.10
2 127.922 2.00 1.84666 23.8 56.80
3 76.612 6.62 1.49700 81.5 55.32
4 1483.135 0.15 54.89
5 66.859 5.86 1.60738 56.8 52.97
6 325.080 (variable) 52.19
7 79.300 1.45 1.91082 35.3 34.09
8 15.595 8.10 25.60
9 -84.291 1.20 1.83481 42.7 25.41
10 42.660 1.31 25.09
11 30.665 6.60 1.84666 23.8 25.97
12 -61.686 1.10 1.77250 49.6 25.43
13 413.544 (variable) 24.76
14 55.003 1.64 1.80518 25.4 14.39
15 1371.106 (variable) 14.24
16 -38.056 0.70 1.90366 31.3 13.97
17 -408.051 (variable) 14.24
18 23.610 3.66 1.60311 60.6 15.70
19 -91.277 1.17 15.49
20 (Aperture) ∞ 2.00 14.83
21 26.328 5.54 1.60311 60.6 14.37
22 -23.088 0.75 1.80000 29.8 13.27
23 -67.471 0.99 12.99
24 -65.002 0.70 1.74950 35.3 12.45
25 15.384 1.91 1.77250 49.6 11.97
26 22.891 1.68 11.65
27 335.732 3.52 1.66680 33.0 11.80
28 -9.868 0.80 1.72047 34.7 11.95
29 630.852 0.15 12.47
30 27.288 2.71 1.85400 40.4 12.79
31 * 110.032 12.83

Aspheric data 31st surface
K = 0.00000e + 000 A 4 = 2.99992e-005 A 6 = -4.29579e-008 A 8 = 2.42140e-009 A10 = -2.39016e-011 A12 = -6.58966e-014

Various data Zoom ratio 5.59

Wide angle Medium Telephoto focal length 18.60 50.00 103.95
F number 3.60 5.09 5.88
Angle of view 36.29 15.28 7.49
Image height 13.66 13.66 13.66
Total lens length 140.57 159.78 190.00
BF 35.64 56.33 67.17

d 6 0.90 24.00 48.93
d13 31.63 7.05 1.50
d15 3.12 4.63 7.52
d17 5.45 3.94 1.05

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 112.03 16.13 4.60 -6.23
2 7 -21.44 19.76 0.40 -15.24
3 14 71.13 1.64 -0.04 -0.95
4 16 -46.49 0.70 -0.04 -0.41
5 18 26.79 25.59 0.25 -17.82

(Numerical example 5)

Unit mm

Surface data surface number rd nd νd Effective diameter
1 ∞ 1.50 64.00
2 95.457 2.00 1.84666 23.8 55.24
3 58.651 7.76 1.49700 81.5 51.80
4 6401.039 0.15 51.35
5 52.248 6.39 1.60311 60.6 49.00
6 239.934 (variable) 48.07
7 165.361 1.45 1.91082 35.3 31.91
8 15.531 7.54 23.98
9 -49.402 1.20 1.77250 49.6 23.78
10 66.413 0.15 23.65
11 30.087 6.94 1.84666 23.8 24.00
12 -34.011 1.10 1.80 400 46.6 23.35
13 87.371 (variable) 22.18
14 100.574 1.83 1.80000 29.8 14.43
15 -68.699 (variable) 14.33
16 -34.220 0.70 1.90366 31.3 14.10
17 126.844 1.50 1.84666 23.8 14.46
18 -120.827 (variable) 14.73
19 22.762 3.93 1.51633 64.1 16.22
20 -47.446 0.83 15.96
21 (Aperture) ∞ 3.30 15.30
22 21.131 5.11 1.60311 60.6 14.32
23 -22.970 0.75 1.84666 23.8 13.16
24 34.807 3.44 12.56
25 -39.697 0.70 1.80000 29.8 12.16
26 11.148 3.12 1.84666 23.8 12.29
27 89.644 (variable) 12.35
28 * 52.726 3.53 1.68893 31.1 14.48
29 -45.855 15.19

Aspheric data 28th surface
K = 0.00000e + 000 A 4 = -3.62046e-005 A 6 = -6.64907e-009 A 8 = -8.20333e-010 A10 = 3.23308e-012 A12 = 1.82226e-014

Various data Zoom ratio 6.45

Wide angle Medium Telephoto focal length 18.60 50.00 120.00
F number 3.48 4.90 5.88
Angle of view 36.29 15.28 6.49
Image height 13.66 13.66 13.66
Total lens length 140.51 161.85 190.00
BF 35.60 57.97 73.10

d 6 0.90 19.59 38.16
d13 24.74 6.80 1.53
d15 3.31 4.95 9.74
d18 7.48 5.84 1.05
d27 3.56 1.79 1.50

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 84.52 17.79 5.05 -6.91
2 7 -15.67 18.38 2.05 -10.62
3 14 51.27 1.83 0.61 -0.42
4 16 -50.94 2.20 -0.41 -1.61
5 19 44.31 21.18 -20.88 -25.10
6 28 36.13 3.53 1.13 -0.99

SP: Aperture IP: Imaging surface L1 to L6: First lens group to sixth lens group Ln, Lp1, Lp2: Lens group that moves in focus, and lens groups Lp, Ln1, Ln2 adjacent to the object side and the image side : A lens group that moves with focus, and a lens group that is adjacent to the object and image sides
Focus: Moving direction of the lens group that moves by focusing

Claims (23)

A lens unit Ln having a negative refractive power composed of two or less lenses that move during focusing and zooming, a lens unit Lp1 having a positive refractive power disposed adjacent to the object side of the lens unit Ln, and the lens unit A zoom lens having a positive refractive power lens unit Lp2 disposed adjacent to the image side of Ln and in which the lens unit Lp1 and the lens unit Lp2 move integrally during zooming,
The distance from the most object-side lens surface of the entire system to the image plane at the wide-angle end is Tlw, the distance from the lens-side lens surface of the lens unit Ln to the image plane at the wide-angle end is Dnw, and the back focus is at the wide-angle end. bfw, the maximum movement amount during focusing of the lens unit Ln at the telephoto end (positive when moving from the object side to the image side during focusing from infinity to the close range) is Mfnt, from the wide angle end to the telephoto end When the amount of change in the interval between the lens unit Ln and the lens unit Lp1 during zooming (the direction in which the interval increases is positive) is Mnz,
0.2 <(Dnw−bfw) / (Tlw−bfw) <0.8
0.3 <-Mnz / Mfnt <1.0
A zoom lens satisfying the following conditional expression: When the focal lengths of the lens group Ln, the lens group Lp1, and the lens group Lp2 are fn, fp1, and fp2, respectively.
0.4 <−fp1 / fn <2.5
0.4 <−fp2 / fn <2.5
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the effective rays on the object side and the image side of the lens group Ln are ea_nf and ea_nr, respectively, and the effective rays on the image side of the lens group Lp1 and the object side of the lens group Lp2 are ea_p1r and ea_p2f, respectively.
0.7 <ea_p1r / ea_nf <1.4
0.7 <ea_p2f / ea_nr <1.4
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. The rear principal point position of the combined lens group of the lens group Lp1, the lens group Ln, and the lens group Lp2 at the wide angle end is okw, the rear principal point position of the lens group Lp2 is okp2, and the focal length of the lens group Lp2 Is fp2,
| (Okw−okp2) / fp2 | <0.3
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the lateral magnification of the lens unit Ln at the wide angle end is βnw,
| Βnw | <1.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the lateral magnification of the lens unit Ln at the telephoto end is βnt,
| Βnt | <1.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. A lens unit Ln having a negative refractive power composed of two or less lenses that move during focusing and zooming, a lens unit Lp1 having a positive refractive power disposed adjacent to the object side of the lens unit Ln, and the lens unit A zoom lens having a positive refractive power lens unit Lp2 arranged adjacent to the image side of Ln, and the lens unit Lp1 and the lens unit Lp2 move during zooming,
  The distance from the most object-side lens surface of the entire system to the image plane at the wide-angle end is Tlw, the distance from the lens-side lens surface of the lens unit Ln to the image plane at the wide-angle end is Dnw, and the back focus is at the wide-angle end. bfw, the maximum movement amount during focusing of the lens unit Ln at the telephoto end (positive when moving from the object side to the image side during focusing from infinity to the close range) is Mfnt, from the wide angle end to the telephoto end An amount of change in the distance between the lens unit Ln and the lens unit Lp1 during zooming (the direction in which the interval increases is positive) is Mnz,
  The rear principal point position of the combined lens group of the lens group Lp1, the lens group Ln, and the lens group Lp2 at the wide angle end is okw, the rear principal point position of the lens group Lp2 is okp2, and the focal length of the lens group Lp2 Is fp2,
  0.2 <(Dnw−bfw) / (Tlw−bfw) <0.8
  0.3 <-Mnz / Mfnt <1.0
  | (Okw−okp2) / fp2 | <0.3
A zoom lens satisfying the following conditional expression: When the focal lengths of the lens group Ln, the lens group Lp1, and the lens group Lp2 are fn, fp1, and fp2, respectively.
  0.4 <−fp1 / fn <2.5
  0.4 <−fp2 / fn <2.5
The zoom lens according to claim 7, wherein the following conditional expression is satisfied.   When the effective beam diameters on the object side and the image side of the lens group Ln are ea_nf and ea_nr, respectively, and the effective beam diameters on the image side of the lens group Lp1 and the object side of the lens group Lp2 are ea_p1r and ea_p2f, respectively.
  0.7 <ea_p1r / ea_nf <1.4
  0.7 <ea_p2f / ea_nr <1.4
The zoom lens according to claim 7, wherein the following conditional expression is satisfied.   When the lateral magnification of the lens unit Ln at the wide angle end is βnw,
  | Βnw | <1.0
The zoom lens according to claim 7, wherein the following conditional expression is satisfied. When the lateral magnification of the lens unit Ln at the telephoto end is βnt,
  | Βnt | <1.0
The zoom lens according to claim 7, wherein the following conditional expression is satisfied. A lens unit Lp having a positive refractive power made up of two or less lenses that move during focusing and zooming, a lens unit Ln1 having a negative refractive power disposed adjacent to the object side of the lens unit Lp, and the lens unit A zoom lens having a negative refractive power lens unit Ln2 disposed adjacent to the image side of Lp, and in which the lens unit Ln1 and the lens unit Ln2 move integrally during zooming,
The distance from the most object-side lens surface of the entire system to the image plane at the wide-angle end is Tlw, the distance from the most image-side lens surface of the lens unit Ln2 to the image plane at the wide-angle end is Dn2w, and the back focus is at the wide-angle end. bfw, the maximum amount of movement during focusing of the lens unit Lp at the telephoto end (positive when moving from the object side to the image side during focusing from infinity to the closest distance) Mfpt, from the wide-angle end to the telephoto end When the amount of change in the distance between the lens unit Lp and the lens unit Ln2 during zooming (the direction in which the interval narrows is positive) is Mpz,
0.2 <(Dn2w−bfw) / (Tlw−bfw) <0.8
0.3 <-Mpz / Mfpt <1.0
A zoom lens satisfying the following conditional expression: When the focal lengths of the lens group Lp, the lens group Ln1, and the lens group Ln2 are fp, fn1, and fn2, respectively.
0.3 <−fn1 / fp <2.5
0.3 <−fn2 / fp <2.5
The zoom lens according to claim 12 , wherein the following conditional expression is satisfied. When the effective beam diameters on the object side and the image side of the lens group Lp are ea_pf and ea_pr, respectively, and the effective beam diameters on the image side of the lens group Ln1 and the object side of the lens group Ln2 are ea_n1r and ea_n2f, respectively.
0.7 <ea_n1r / ea_pf <1.4
0.7 <ea_n2f / ea_pr <1.4
The zoom lens according to claim 12, wherein the following conditional expression is satisfied. The front principal point position of the combined lens group of the lens group Ln1, the lens group Lp, and the lens group Ln2 at the wide angle end is o1w, the front principal point position of the lens group Ln1 is o1n1, and the focal length of the lens group Ln1 is fn1. And when
| (O1w−o1n1) / fn1 | <0.3
The zoom lens according to claim 12, wherein the following conditional expression is satisfied. When the lateral magnification of the lens unit Ln2 at the wide angle end is βn2w,
| Βn2w | <1.0
The zoom lens according to claim 12, wherein the following conditional expression is satisfied. When the lateral magnification of the lens unit Ln2 at the telephoto end is βn2t,
| Βn2t | <1.0
The zoom lens according to claim 12, wherein the following conditional expression is satisfied. A lens unit Lp having a positive refractive power made up of two or less lenses that move during focusing and zooming, a lens unit Ln1 having a negative refractive power disposed adjacent to the object side of the lens unit Lp, and the lens unit A zoom lens having a negative refractive power lens unit Ln2 disposed adjacent to the image side of Lp, and moving the lens unit Ln1 and the lens unit Ln2 during zooming,
  The distance from the most object-side lens surface of the entire system to the image plane at the wide-angle end is Tlw, the distance from the most image-side lens surface of the lens unit Ln2 to the image plane at the wide-angle end is Dn2w, and the back focus is at the wide-angle end. bfw, the maximum amount of movement during focusing of the lens unit Lp at the telephoto end (positive when moving from the object side to the image side during focusing from infinity to the closest distance) Mfpt, from the wide-angle end to the telephoto end The amount of change in the distance between the lens unit Lp and the lens unit Ln2 during zooming (the direction in which the interval narrows is positive) is expressed as Mpz,
The front principal point position of the combined lens group of the lens group Ln1, the lens group Lp, and the lens group Ln2 at the wide angle end is o1w, the front principal point position of the lens group Ln1 is o1n1, and the focal length of the lens group Ln1 is fn1. And when
  0.2 <(Dn2w−bfw) / (Tlw−bfw) <0.8
  0.3 <-Mpz / Mfpt <1.0
  | (O1w−o1n1) / fn1 | <0.3
A zoom lens satisfying the following conditional expression: When the focal lengths of the lens group Lp, the lens group Ln1, and the lens group Ln2 are fp, fn1, and fn2, respectively.
  0.3 <−fn1 / fp <2.5
  0.3 <−fn2 / fp <2.5
The zoom lens according to claim 18, wherein the following conditional expression is satisfied.   When the effective beam diameters on the object side and the image side of the lens group Lp are ea_pf and ea_pr, respectively, and the effective beam diameters on the image side of the lens group Ln1 and the object side of the lens group Ln2 are ea_n1r and ea_n2f, respectively.
  0.7 <ea_n1r / ea_pf <1.4
  0.7 <ea_n2f / ea_pr <1.4
The zoom lens according to claim 18, wherein the following conditional expression is satisfied.   When the lateral magnification of the lens unit Ln2 at the wide angle end is βn2w,
  | Βn2w | <1.0
The zoom lens according to claim 18, wherein the following conditional expression is satisfied.   When the lateral magnification of the lens unit Ln2 at the telephoto end is βn2t,
  | Βn2t | <1.0
The zoom lens according to claim 18, wherein the following conditional expression is satisfied. An image pickup apparatus comprising the zoom lens according to any one of claims 1 to 22 .