JP2004334185A - Zoom lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a compact zoom lens through which excellent picture quality can be obtained irrespective of an object distance. <P>SOLUTION: The zoom lens comprises a 1st lens group L1 with positive refracting power, a 2nd lens group L2 with positive refracting power, a 3rd lens group with positive refracting power in this order from the object side to the image side, and in zooming, the gap between the 1st lens group L1 and the 2nd lens group L2 and the gap between the 2nd lens group L2 and the 3rd lens group L3 are varied; and the 2nd lens group L2 comprises a (2a)th lens group L2A with positive or negative refracting power and a (2b)th lens group L2B with positive refracting power in this order from the object side to the image side. In focusing on a short-distance body from an infinite-distance body at least one zooming position, at least the (2b)th lens group L2B is moved toward the object side so as to change the gap between the (2a)th lens group L2A and (2b)th lens group L2B. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a zoom lens, and is particularly suitable for a photographing optical system of a camera.

  2. Description of the Related Art In recent years, a compact and high-performance photographing optical system has been required as a photographing optical system for a camera.

  In particular, in the shooting optical system of a lens shutter camera, the development of peripheral mechanical mechanisms and electric circuits has made it possible to achieve miniaturization of the camera. The achievement of a zoom lens is desired.

  As a photographing optical system for a lens shutter camera, for example, Patent Documents 1 and 2 disclose a zoom lens composed of three lens groups having positive, positive, and negative refractive power in order from the object side. ing.

  Further, Patent Literatures 3 and 4 propose zoom lenses having a zoom ratio of about 3 to 4 and composed of four lens groups of negative, positive, positive, and negative refractive power in order from the object side.

  Further, Japanese Patent Application Laid-Open Nos. H11-163191, H11-107, and the like propose a focus method that suppresses fluctuation of aberration at a short distance.

In Patent Literature 7, four focusing lens units having positive, positive, positive, and negative refracting power from the object side are provided. As a focusing method other than the first lens unit, the second and third lens units are specifically described. A method of moving the lens unit integrally and a method of moving the fourth lens group have been proposed.
JP-A-8-262325 JP-A-9-120028 JP-A-9-15499 JP-A-10-31155 JP-A-4-338910 JP-A-8-220438 JP-A-3-249614

  However, when an attempt is made to realize a zoom lens with a higher zoom ratio and a smaller size, a change in optical performance during focusing tends to occur. It becomes difficult to achieve good optical performance over the entire zoom range while suppressing such changes in optical performance.

  The present invention provides a compact zoom lens while maintaining high image quality even at the time of close-up shooting by devising an appropriate zoom lens configuration and lens group arrangement, and devising a method of moving a lens group to be moved during focusing. It is.

  The zoom lens of the present invention includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a positive refractive power, and a third lens group having a negative refractive power. The distance between the first lens group and the second lens group and the distance between the second lens group and the third lens group are changed. The second lens group includes, in order from the object side to the image side, a second a lens group having a positive or negative refractive power and a second b lens group having a positive refractive power. Then, at the time of focusing from an object at infinity to a close object at at least one zoom position, at least the second lens group is moved to the object side so that the distance between the second lens group and the second lens group changes. It is characterized by:

  ADVANTAGE OF THE INVENTION According to this invention, the compact zoom lens which can maintain favorable optical performance even at the time of imaging | photography of a close-range object can be implement | achieved.

  Embodiments of the zoom lens system according to the present invention will be described with reference to the drawings. The zoom lens system disclosed in the present embodiment is particularly suitable as a photographing optical system for a compact camera, and has a zoom ratio of about 4.5 and can obtain good image quality even at the time of short-range photographing.

  1, 7, 13, 19, and 25 are cross-sectional views of zoom lens systems according to Numerical Examples 1 to 5, which will be described later. In these lens sectional views, L1 is a first lens group having a positive refractive power (optical power = reciprocal of the focal length), L2 is a second lens group having a positive refractive power as a whole, and L3 is a negative lens having a negative refractive power. This is the third lens group. The second lens unit L2 includes a second lens unit L2A having a positive or negative refractive power and a second lens unit L2B having a positive refractive power. SP is an aperture stop, and IP is an image plane on which a silver halide film or the like is arranged.

  2, 8, 14, 20, and 26 show various aberration diagrams when the zoom lens system of each numerical example focuses on an object at infinity.

  The refractive powers of the second-a lens units L2A in Numerical Examples 1 to 3 are negative, and the refractive powers of the second-a lens units L2A in Numerical Examples 4 and 5 are positive.

  The zoom lens system according to the present embodiment performs zooming by changing the distance between the first lens unit L1 and the second lens unit L2 and the distance between the second lens unit L2 and the third lens unit L3.

  In the zoom lens systems of Numerical Examples 1, 2, and 4, during zooming, the distance between the second-a lens unit L2A and the second-b lens unit L2B is also changed. That is, the zoom lens systems of Numerical Examples 1 and 2 are a four-unit zoom lens including a lens unit having positive, negative, positive, and negative refractive power in order from the object side to the image side. A four-unit zoom lens including four lens units having positive, positive, positive, and negative refractive power in order from the object side to the image side.

  In the zoom lens systems of Numerical Examples 3 and 5, the distance between the second-a lens unit L2A and the second-b lens unit L2B does not change during zooming. That is, the zoom lens systems of Numerical Examples 3 and 5 are three-unit zoom lenses including lens units having positive, positive, and negative refractive power in order from the object side to the image side.

  As in the zoom lens systems of Numerical Examples 1, 2, and 4, during zooming, the distance between the second-a lens unit L2A and the second-b lens unit L2B is changed so that spherical aberration and off-axis aberration are corrected in a well-balanced manner. Therefore, a higher quality zoom lens system can be expected over the entire zoom range.

  The zoom lens system according to the present embodiment focuses from an object at infinity to an object at a short distance by extending the second-a lens unit L2A and the second-b lens unit L2B toward the object side. In at least one zoom position in the zoom range, at least the second lens unit L2B is moved to the object side so that the air gap between the second lens unit L2A and the second lens unit L2B changes, and the object at infinity is moved. Focuses on objects at close range.

  This allows the second-b lens unit L2B to mainly perform the image plane position correction function at the time of focusing, and appropriately adjusts the relative position of the second-a lens unit L2A and the second-b lens unit L2B by changing the aberration due to a change in the object distance. Since it can be suppressed by setting, good image quality can be realized at all object distances.

  In particular, at the wide-angle end, when focusing from an object at infinity to an object at a short distance, the lens units are relatively moved on the optical axis such that the air gap between the second lens unit L2A and the second lens unit L2B is increased. Is preferable, whereby the 2a-th lens unit L2A comes closer to the first lens unit L1, so that off-axis rays are incident around the lens of the 2a-th lens unit L2A, and the field curvature is positively corrected. be able to.

  In particular, at the telephoto end, at the time of focusing from an object at infinity to an object at a short distance, at least the second lens unit L2B may be moved so that the air gap between the second lens unit L2A and the second lens unit L2B is reduced. desirable. This makes it possible to favorably correct positive spherical aberration that occurs when focusing on an object at a finite distance compared to when focusing on an object at infinity.

  As a method of moving the lens groups at the time of focusing, a method of separately driving only the focus lens group by an electric driving means (direct driving method) or a cam mechanism for moving each lens group at the time of zooming There is a method of driving a focus lens group using a zoom lens (a method using a zoom cam), and any of them can be applied to the zoom lens system of the present embodiment. FIG. 31 schematically shows the zoom locus and the focus movement of each lens group in the former method. FIG. 32 schematically shows a zoom locus in the latter method and a focus moving locus at each zoom position.

  In the method shown in FIG. 32, a focus cam for a certain zoom position is formed between an object position at infinity at a certain zoom position and an object position at infinity at the next zoom position, and this cam is used. Focuses from an object at infinity to a close object at the zoom position. At this time, as can be seen from FIG. 32, not only the second lens group L2A and the second lens group L2b, but also the first lens group L1 and the third lens group L3 are simultaneously moved on the optical axis. Adopting such a system in which a part of a driving cam for zooming is used for focus driving is advantageous in simplifying the mechanical mechanism.

  In the present embodiment, the first lens unit L1 includes a negative meniscus lens having a concave surface facing the object side and a convex shape having a stronger refractive power on the object side than the image side, disposed on the image side. It is composed of a positive lens having a surface. The first lens unit L1 having such a configuration efficiently corrects spherical aberration and distortion.

  The 2a-th lens unit L2A has a positive lens and a negative lens to suppress chromatic aberration fluctuation during zooming. Further, by using the positive lens and the negative lens as cemented lenses, a further color correction effect is obtained.

  The second lens unit L2B is a positive lens having a lens component having a negative refractive power (a negative lens or a negative cemented lens) on the object side and an aspherical surface on the image side in order to satisfactorily correct spherical aberration over the entire zoom range. Is placed. An aperture stop SP is arranged in the second lens unit L2B in order to reduce the size of the entire zoom lens system and to satisfactorily correct off-axis aberrations. It is desirable that the aperture stop SP is arranged at a position close to the center of the optical system in order to balance the diameter of the front lens and the diameter of the rear lens and obtain good optical performance.

  The third lens unit L3 includes a positive lens having an aspheric surface, and a negative lens having a concave surface having a stronger refractive power on the object side than the image side, which is disposed on the image side. I have. Thus, efficient off-axis aberration correction is performed with a small number of lenses.

  Further, desirable conditions of the zoom lens system according to the present embodiment will be described.

First, in order to achieve a small and high-quality optical system with a high zoom ratio, it is desirable to satisfy the following conditional expression at the wide-angle end.
0.3 <| F3 / Fw | <0.7 (1)
1.0 <β3w <2.0 (2)
Where Fw: focal length of the entire zoom lens system at the wide-angle end F3: focal length of the third lens unit L3 β3w: lateral magnification of the third lens unit L3 at the wide-angle end

  The conditional expressions (1) and (2) relate to the refractive power of the third lens unit L3 at the wide angle end.

  The negative refractive power of the third lens unit L3 is weakened beyond the upper limit of conditional expression (1), or the lateral magnification at the wide-angle end of the third lens unit L3 is exceeded beyond the upper limit of conditional expression (2). If it is too large, the zooming effect of the third lens unit L3 during zooming will be weak. For this reason, in order to obtain a desired zoom ratio, the amount of movement of each lens group during zooming must be increased, and as a result, the overall length of the lens becomes longer, which is not preferable.

  On the other hand, if either of the conditional expressions (1) and (2) is below the lower limit, the back focus becomes too short because the effect of the telephoto system as a whole becomes stronger. In addition, in order to secure a constant amount of peripheral light, the lens outer diameter of the third lens unit L3 is increased, and at the same time, curvature of field and astigmatism are generated.

In order to achieve good image quality even at the time of short-distance shooting while achieving downsizing of the lens system, it is desirable to satisfy the following conditional expressions.
0.03 <| F2b / F2a | <0.4 (3)
Where F2a: focal length of the 2a-th lens unit L2A F2b: focal length of the 2b-th lens unit L2B

  When the positive refractive power of the second lens subunit L2A becomes weaker than the upper limit of conditional expression (3), the negative refractive power of the third lens subunit L3 decreases to obtain a desired focal length at the wide angle end. It must be weakened, and at the same time as the zooming effect at the time of constant movement during zooming is weakened, the movement amount of the second lens subunit L2B at the time of focusing on an object at a finite distance becomes large. As a result, the lens system becomes large.

  On the other hand, when the value exceeds the lower limit, the positive refractive power of the second lens unit L2B becomes too strong, and high-order spherical aberration is generated largely. It becomes difficult to correct this, which is not good.

If the numerical range of conditional expression (3) is limited to the following range, the above-mentioned effects are more remarkable, and it is desirable.
0.03 <| F2b / F2a | <0.2 (3a)

  Further, on the assumption that the entire second lens unit L2 has a predetermined focal length, in order to reduce the amount of movement of the focus lens unit and downsize the lens system, the refractive power of the second-a lens unit L2A must be reduced. It is advantageous to increase the positive refractive power of the second-b lens unit L2B to a negative value, because the amount of movement for focusing at a certain finite distance can be reduced.

  In the present embodiment, a plastic lens having one aspherical surface is introduced into the third lens unit L3, but a plurality of plastic lenses may be introduced for further cost reduction.

  Further, in order to improve the optical performance, a further aspherical surface, a diffractive optical element, or a gradient lens may be introduced.

  Further, the lens group or a part of the lens group may be decentered so as to correct an image position displacement caused by camera shake or the like.

  Next, numerical data of Numerical Examples 1 to 5 are shown.

  In each numerical example, f indicates a focal length, Fno indicates an F number, and ω indicates a half angle of view. 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 Ni and νi are each It shows the refractive index and Abbe number of the material of the i-th optical member with respect to the d-line.

  When k is a conical constant, B, C, D, and E are aspherical coefficients, and the displacement in the optical axis direction at a height h from the optical axis is x with respect to the surface vertex, the aspherical shape is ,

Is displayed with. Here, R is a paraxial radius of curvature. Also, for example "e-Z" means ^{"10 -Z".}

  Table 1 shows the correspondence with the above-described conditional expressions in each numerical example.

  Table 2-1 shows a case in which the distance between the second-a lens unit L1A and the second-b lens unit L2B is not changed, and the direct drive method shown in FIG. The movement amount of the focus lens group (second lens group L2) is shown.

  In addition, Table 2-2 shows that, without changing the distance between the 2a-th lens unit L1A and the 2b-th lens unit L2B, focusing on an object at infinity using the zoom cam method shown in FIG. The movement amounts of the focus lens unit (second lens unit L2), the first lens unit L1, and the third lens unit L3 in the case are shown.

  Table 2-3 shows that the distance between the second-a lens unit L1A and the second-b lens unit L2B is changed to focus on an object at a distance of 80 cm from the state of focusing on an object at infinity by the direct drive method shown in FIG. The movement amounts of the lens units (the second-a lens unit L1A and the second-b lens unit L2B) are shown.

  Table 2-4 shows that the distance between the second-a lens unit L1A and the second-b lens unit L2B is changed to focus on an object at a distance of 80 cm from the state of focusing on an object at infinity using the zoom cam method shown in FIG. 3 shows the movement amounts of the focus lens groups (the 2a lens group L1A and the 2b lens group L2B), the first lens group L1, and the third lens group L3.

  Each of FIGS. 3, 9, 15, 21, and 27 was implemented by changing the distance between the second-a lens unit L1A and the second-b lens unit L2B and focusing on an object at a distance of 80 cm by the direct drive method shown in FIG. FIG. 4 shows various aberration diagrams of the example zoom lens system. In addition, in FIGS. 4, 10, 16, 22, and 28, the distance between the second-a lens unit L1A and the second-b lens unit L2B is changed to focus on an object at a distance of 80 cm using the zoom cam system shown in FIG. FIG. 3 shows various aberration diagrams of the zoom lens system of a numerical example.

  Further, as a comparative example, the direct drive method shown in FIG. 31 focuses on an object at a distance of 80 cm without changing the distance between the 2a-th lens unit L1A and the 2b-th lens unit L2B in FIGS. 5, 11, 17, 23, and 29. FIG. 3 shows various aberration diagrams of the zoom lens system according to each numerical example in a state where the zoom lens system is set. Similarly, as a comparative example, focusing on an object at a distance of 80 cm by using the zoom cam system shown in FIG. 32 without changing the distance between the second-a lens unit L1A and the second-b lens unit L2B in FIGS. 6, 12, 18, 24, and 30. FIG. 3 shows various aberration diagrams of the zoom lens system according to each numerical example in a state where the zoom lens system is in a state of being set.

  By moving at least the second lens subunit L2B to the object side so as to change the distance between the second lens subunit L2A and the second b lens subunit L2B and focusing from an object at infinity to an object at a short distance, It can be seen from the comparison of the aberration diagrams of the comparative example that the off-axis curvature of field is particularly well corrected and the spherical aberration is particularly well corrected at the telephoto end.

  Next, an embodiment of a compact camera of a lens shutter system using the zoom lens system of the present invention as a photographing optical system will be described with reference to FIG.

  33, reference numeral 10 denotes a compact camera main body, 11 denotes a photographing optical system constituted by the zoom lens system of the present invention, 12 denotes a strobe built in the camera main body, and 13 denotes a different optical axis from the photographing optical system 11. An external viewfinder system 14 is a shutter button.

  As described above, by applying the zoom lens of the present invention to an optical device such as a lens shutter camera, an optical device having a small size and high optical performance is realized.

FIG. 2 is a lens configuration diagram of a zoom lens system according to Numerical Example 1. FIG. 5 is an aberration diagram at a wide-angle end, an intermediate zoom position, and a telephoto end of the zoom lens system according to Numerical Example 1 in a state where an object at infinity is focused. Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 1 in a case where focusing is performed on an object at a distance of 80 cm while changing the distance between the 2a lens group and the 2b lens group (direct drive method) It is. Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 1 when focusing is performed on an object at a distance of 80 cm while changing the distance between the 2a lens group and the 2b lens group (using a zoom cam). It is. Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 1 when focusing is performed on an object at a distance of 80 cm without changing the distance between the second lens unit and the second lens unit (direct driving method). It is. (Comparative example) Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 1 when focusing is performed on an object at a distance of 80 cm without changing the distance between the second lens group and the second lens group (using a zoom cam). It is. (Comparative example) FIG. 9 is a lens configuration diagram of a zoom lens system according to Numerical Example 2. FIG. 10 is an aberration diagram at a wide-angle end, an intermediate zoom position, and a telephoto end of the zoom lens system according to Numerical Example 2 in a state where an object at infinity is focused. Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 2 when focusing is performed on an object at a distance of 80 cm while changing the distance between the 2a lens group and the 2b lens group (direct drive method) It is. Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 2 when focusing is performed on an object at a distance of 80 cm while changing the distance between the 2a lens group and the 2b lens group (using a zoom cam). It is. Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 2 when focusing is performed on an object at a distance of 80 cm without changing the distance between the second lens unit and the second lens unit (direct driving method). It is. (Comparative example) Aberration diagrams at the wide-angle end and at the telephoto end of the zoom lens system according to Numerical Example 2 when focusing is performed on an object at a distance of 80 cm without changing the distance between the second lens unit and the second lens unit (using a zoom cam). It is. (Comparative example) FIG. 13 is a lens configuration diagram of a zoom lens system according to Numerical Example 3. FIG. 13 is an aberration diagram at a wide-angle end, an intermediate zoom position, and a telephoto end of the zoom lens system according to Numerical Example 3 in a state where an object at infinity is focused. FIG. 14 is an aberration diagram at a wide-angle end of a zoom lens system according to Numerical Example 3 when focusing is performed on an object at a distance of 80 cm while changing the distance between the second lens group and the second b lens group (direct drive method). FIG. 13 is an aberration diagram at a wide-angle end of a zoom lens system according to Numerical Example 3 in a case where focusing is performed on an object at a distance of 80 cm while changing the distance between the second lens unit and the second lens unit (using a zoom cam). Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 3 when focusing is performed on an object at a distance of 80 cm without changing the distance between the 2a lens group and the 2b lens group (direct drive method) It is. (Comparative example) Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 3 when focusing is performed on an object at a distance of 80 cm without changing the distance between the second lens unit and the second lens unit (using a zoom cam). It is. (Comparative example) FIG. 14 is a lens configuration diagram of a zoom lens system according to Numerical Example 4. FIG. 12 is an aberration diagram at a wide-angle end, an intermediate zoom position, and a telephoto end of the zoom lens system according to Numerical Example 4 in a state where an object at infinity is focused. Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 4 when focusing is performed on an object at a distance of 80 cm while changing the distance between the 2a lens group and the 2b lens group (direct drive method) It is. Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 4 when focusing is performed on an object at a distance of 80 cm while changing the distance between the 2a lens group and the 2b lens group (using a zoom cam). It is. Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 4 when focusing is performed on an object at a distance of 80 cm without changing the distance between the second lens unit and the second lens unit (direct drive method) It is. (Comparative example) Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 4 when focusing is performed on an object at a distance of 80 cm without changing the distance between the second lens group and the second lens group (using a zoom cam). It is. (Comparative example) FIG. 15 is a lens configuration diagram of a zoom lens system according to Numerical Example 5. FIG. 14 is an aberration diagram at a wide-angle end, an intermediate zoom position, and a telephoto end of the zoom lens system according to Numerical Example 5 in a state where an object at infinity is focused. FIG. 14 is an aberration diagram at a telephoto end of a zoom lens system according to Numerical Example 5 in a case where focusing is performed on an object at a distance of 80 cm while changing the distance between the 2a lens group and the 2b lens group (direct drive method). Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 5 when focusing is performed on an object at a distance of 80 cm while changing the distance between the 2a lens group and the 2b lens group (using a zoom cam). It is. Aberration diagrams at the wide-angle end and the telephoto end of the zoom lens system according to Numerical Example 5 when focusing is performed on an object at a distance of 80 cm without changing the distance between the second lens unit and the second lens unit (direct drive method). It is. (Comparative example) Aberration diagrams at the wide-angle end and at the telephoto end of the zoom lens system according to Numerical Example 5 when focusing is performed on an object at a distance of 80 cm without changing the distance between the second lens unit and the second lens unit (using a zoom cam). It is. (Comparative example) FIG. 5 schematically shows a zoom locus and a focus movement in a method of directly moving the second-a lens group and the second-b lens group by an electric driving means (direct driving method). 4 schematically shows a zoom locus in a method of performing a focus movement of a focus lens group using a part of a zoom cam (a zoom cam utilizing method) and a focus movement locus at each zoom position. It is a schematic structure figure of a compact camera.

Explanation of reference numerals

L1 1st lens group L2 2nd lens group L3 3rd lens group L2A 2a lens group L2B 2b lens group SP Aperture stop IP Image plane dd line gg line S.L. C Curve satisfying the sine condition △ S Sagittal image plane △ M Meridional image plane

Claims (12)

  In order from the object side to the image side, the zoom lens includes a first lens group having a positive refractive power, a second lens group having a positive refractive power, and a third lens group having a negative refractive power. In a zoom lens in which the distance between the second lens group and the distance between the second lens group and the third lens group changes, the second lens group has positive or negative refractive power in order from the object side to the image side. A 2a lens group, and a 2b lens group having a positive refractive power. When focusing from an object at infinity to an object at a short distance at at least one zoom position, the 2a lens group and the 2b lens group A zoom lens, wherein the 2b-th lens unit moves toward the object side so as to change an interval.   The zoom lens according to claim 1, wherein the first lens group and the third lens group move toward the object side when focusing from an object at infinity to an object at a short distance.   3. The zoom lens according to claim 1, wherein at the time of focusing from an object at infinity to a close object at the wide-angle end, an interval between the second lens unit and the second lens unit increases. 4.   The zoom lens according to any one of claims 1 to 3, wherein at the time of focusing from an object at infinity to a close object at the telephoto end, an interval between the second lens group and the second lens group is reduced. When Fw is the focal length of the entire zoom lens system at the wide-angle end, F3 is the focal length of the third lens group, and β3w is the lateral magnification at the wide-angle end of the third lens group.
0.3 | F3 / Fw | <0.7
1.0 <β3w <2.0
The zoom lens according to any one of claims 1 to 4, wherein the following condition is satisfied. When F2a is the focal length of the 2a lens group and F2b is the focal length of the 2b lens group,
0.03 <| F2b / F2a | <0.4
The zoom lens according to any one of claims 1 to 5, wherein the following condition is satisfied.   7. The zoom lens according to claim 1, wherein a distance between the second lens group and the second lens group changes during zooming.   The first lens group includes, in order from the object side to the image side, a negative meniscus lens having a concave surface facing the object side, and a positive lens having a convex surface having a stronger refractive power on the object side than the image side. The zoom lens according to claim 1, further comprising an element.   9. The zoom lens according to claim 1, wherein the second lens group includes a positive lens and a negative lens.   10. The 2b lens group includes, in order from the object side to the image side, a lens component having a negative refractive power, an aperture stop, and a positive lens having an aspheric surface on the image side. 2. The zoom lens according to claim 1.   The third lens group includes, in order from the object side to the image side, a positive lens having an aspheric surface, and a negative lens having a concave surface having a stronger refractive power on the object side than the image side. The zoom lens according to any one of claims 1 to 10, wherein   A camera comprising: the zoom lens according to claim 1; and a finder system having a different optical axis from the zoom lens.

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