CN211263931U - Lens and camera device - Google Patents

Abstract

The application relates to the technical field of zoom lenses and provides a lens and an image pickup device. The lens comprises a first lens group and a second lens group with positive focal power, and a third lens group with negative focal power, wherein the first lens group, the second lens group and the third lens group are arranged in sequence from the object side to the image side along an optical axis; when the lens zooms from infinity to a close position, the first lens group and the third lens group are fixed relative to an image plane, and the second lens group moves to the object side; the focal length of the lens and the focal length of the first lens group satisfy: f is not less than 1₁/F is less than or equal to 2, wherein F represents the focal length of the lens, and F₁The composite focal length of the first lens group is indicated. The entrance pupil is located closer to the object side and has a sizeCorrespondingly, under the condition that the field angles are the same, the intersection point of the principal ray and the lens is closer to the optical axis, various aberrations of the first lens group are reduced, various aberration factors can be eliminated only by small amount of correction, and the diameter of the first lens group and the size of each lens in the lens are reduced.

Description

Lens and camera device

Technical Field

The present disclosure relates to zoom lenses, and particularly to a lens and an image capturing apparatus.

Background

In the field of zoom lenses, an imaging lens with a field angle of 55 ° to 75 ° is generally called a full-frame standard portrait lens, and is suitable for taking a portrait at a distance of 1.5m to 2m, and the zoom range is generally 70mm to 135 mm. For this type of lenses, a Triplet (Triplet) configuration is generally used when the F-number (also called F-number, numerically equal to the reciprocal of the relative aperture, i.e. image distance/aperture implementation) is large, whereas a double gaussian configuration is generally used for large aperture standard lenses with F-numbers less than 2. In a double-gauss lens, opposite concave symmetrical structures are generally adopted on two sides of a diaphragm, and although the lens structure has the problems of large Petzval (Petzval) value and large field curvature of the lens, the spherical aberration and the position chromatic aberration can be effectively reduced, so that the requirements of the lens on high image quality are met while the lens aperture is improved.

In the traditional lens structure, because the double-gauss lens belongs to a symmetrical structure, the focusing lens is often a lens group comprising a plurality of lenses, larger power and energy consumption are needed during electric focusing, and the focusing speed is too slow and inaccurate.

SUMMERY OF THE UTILITY MODEL

The application aims to provide a lens, and aims to solve the technical problem that the number of lenses required to be moved is too large when the traditional lens is focused.

The present application is achieved by a lens barrel including a first lens group and a second lens group having positive refractive power, and a third lens group having negative refractive power, the first lens group, the second lens group, and the third lens group being arranged in order along an optical axis from an object side to an image side;

the first lens group and the third lens group are fixed with respect to an image plane and the second lens group moves to the object side upon zooming from infinity to close of the lens;

the focal length of the lens and the focal length of the first lens group satisfy:

1≤F₁/F≤2，

wherein F represents the focal length of the lens, and F₁Representing a combined focal length of the first lens group.

In one embodiment of the present application, the first lens group includes a first negative lens, a second positive lens, a third negative lens, a fourth positive lens, and a fifth positive lens arranged in this order from an object side to an image side along an optical axis, the first negative lens satisfying:

0.5≤(R₁₁+R₁₂)/(R₁₁-R₁₂)≤3，

wherein R is₁₁Represents a radius of curvature, R, of a surface of the first negative lens facing the object side₁₂And the curvature radius of the surface of the first negative lens, which is opposite to the image side, is shown.

In an embodiment of the present application, the lens further includes a diaphragm, and the diaphragm is coaxial with the lens and disposed between the fourth positive lens and the fifth positive lens.

In one embodiment of the present application, the fourth positive lens satisfies:

60≤ν_d4≤90，

wherein, v_d4Represents an abbe number of the fourth positive lens.

In one embodiment of the present application, the fifth positive lens satisfies:

1.8≤n_d≤2.0，

wherein n is_dRepresents a refractive index of the fifth positive lens.

In one embodiment of the present application, the second lens group includes an achromatic lens group and an eighth positive lens arranged in order from an object side to an image side along an optical axis, the achromatic lens group includes a sixth positive lens and a seventh negative lens closely attached, and the sixth positive lens and the seventh negative lens satisfy:

nd_j1≤nd_j2；vd_j1≥vd_j2，

therein, nd_j1And nd_j2Respectively represent refractive indexes, vd, of the sixth positive lens and the seventh negative lens_j1And vd_j2Respectively represent the secondAbbe numbers of the six positive lenses and the seventh negative lens.

In one embodiment of the present application, the eighth positive lens is an aspherical lens, and the eighth positive lens satisfies:

1.70≤n_d8≤1.90；40≤ν_d8≤70，

wherein n is_d8Denotes a refractive index, v, of the eighth positive lens_d8Represents an abbe number of the eighth positive lens.

In one embodiment of the present application, the third lens group satisfies:

-1.5≤F₃/F≤-0.7，

wherein, F₃Denotes a focal length of the third lens group.

In one embodiment of the present application, the lens satisfies:

0.3≤B_f/F≤0.7，

wherein, B_fRepresenting the distance between the lens surface of the lens closest to the image plane and the image plane.

Another object of the present application is to provide an image pickup apparatus including the lens barrel as described above.

The implementation of the lens of the application can at least achieve the following beneficial effects:

through setting up the focus of first lens group at the focus that is greater than or equal to the camera lens, and be less than or equal to the within range of the twice of the focus of camera lens, can optimize the field of view scope and the position of entrance pupil, concretely, the position of entrance pupil is more close to the object side and the size of entrance pupil reduces correspondingly, like this under the same circumstances of field angle, make the intersect distance optical axis of chief ray and lens closer, and then reduced the diameter of first lens group, the aberration such as chromatic aberration, spherical aberration, coma, phase transition, curvature of field and distortion of first lens group reduce along with it, only need a small amount of corrections can eliminate each aberration factor, the size of each lens in the camera lens has finally been reduced.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a lens according to an embodiment of the present application;

FIG. 2 is a graph of the trend of the lens of FIG. 1 in the longitudinal aberration when focused on an object far from the lens;

FIG. 3 is a graph of the trend of the curvature of field and distortion of the lens of FIG. 1 when focused on an object far from the lens;

FIG. 4 is a graph of the trend of the longitudinal aberration of the lens of FIG. 1 when focused at 0.35 meters;

FIG. 5 is a graph of the trend of the field curvature and distortion of the lens of FIG. 1 when focused at 0.35 meters;

fig. 6 is a schematic structural diagram of a lens provided in the second embodiment of the present application;

FIG. 7 is a trend graph of longitudinal aberration when the lens of FIG. 6 is focused on an object far from the lens;

FIG. 8 is a graph of the trend of the curvature of field and distortion of the lens of FIG. 6 when focused on an object far from the lens;

FIG. 9 is a graph of the trend of the longitudinal aberration when the lens of FIG. 6 is focused at 0.35 meters;

FIG. 10 is a graph of the trend of the field curvature and distortion of the lens of FIG. 6 when focused at 0.35 meters;

the F, d and C lines in FIGS. 2, 4, 7 and 9 represent spherical aberration at the F (486 nm wavelength), d (588 nm wavelength) and C (656 nm wavelength), respectively; the S-line in fig. 3, 5, 8 and 10 represents the value of the principal ray d at the sagittal image surface under the corresponding imaging condition, and the T-line represents the value of the principal ray d at the meridional image surface under the corresponding imaging condition.

Reference numerals referred to in the above figures are detailed below:

GR 1-first lens group; g₁₁-a first negative lens; g₁₂-a second positive lens; g₁₃-a third negative lens; g₁₄-a fourth positive lens; g₁₅-a fifth positive lens; GR 2-second lens group; g₂₁-an achromatic lens group; g_j1-a sixth positive lens; g_j2-a seventh negative lens; g₂₂-an eighth positive lens; GR 3-third lens group; g₃₁-a ninth negative lens; GL-parallel glass plates; IMG-image plane; SP-diaphragm.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly or indirectly secured to the other element. When an element is referred to as being "connected to" another element, it can be directly or indirectly connected to the other element. The terms "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positions based on the orientations or positions shown in the drawings, and are for convenience of description only and not to be construed as limiting the technical solution. The terms "first", "second" … … "ninth" are used merely for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features. The meaning of "plurality" is two or more unless specifically limited otherwise.

In order to explain the technical solutions of the present application, the following detailed descriptions are made with reference to specific drawings and examples.

Referring to fig. 1 and fig. 6, the present embodiment provides a lens assembly, including a first lens group GR1, a second lens group GR2, and a third lens group GR3, which have positive powers, wherein the first lens group GR1, the second lens group GR2, and the third lens group GR3 are sequentially disposed along an optical axis from an object side to an image side;

upon zooming from infinity to close, the first lens group GR1 and the third lens group GR3 are fixed with respect to the image plane IMG, and the second lens group GR2 is moved to the object side;

the focal length of the lens and the focal length of the first lens group GR1 satisfy the condition (1):

1≤F₁/F≤2，

wherein F represents the focal length of the lens, and F₁The combined focal length of the first lens group GR1 is indicated.

The implementation of the lens of the application can at least achieve the following beneficial effects:

through setting the focal length of first lens group GR1 at the focus that is greater than or equal to the camera lens, and be less than or equal to the focus of camera lens within the range of the twice of the camera lens, can optimize the field of view scope and the position of entrance pupil, it is specific, the position of entrance pupil is more close to the object side and the size of entrance pupil reduces correspondingly, like this under the same circumstances of field angle, make the point of intersection distance optical axis of chief ray and lens closer, and then reduced the diameter of first lens group GR1, the aberration such as chromatic aberration, spherical aberration, coma, phase transition, curvature of field and distortion of first lens group GR1 reduce along with it, only need a small amount of corrections can eliminate each aberration factor, finally reduced the size of each lens in the camera lens.

With the lens provided in this embodiment, when the ratio of the combined focal length of the first lens group GR1 to the focal length of the lens is lower than the lower limit of the condition (1), the focal length of the first lens group GR1 is too small, the focal power is too large, the lens aperture of the first lens group GR1 is increased, and various aberrations such as spherical aberration generated by the first lens group GR1 are corrected by the second lens group GR2 and the third lens group GR3, so that the structures of the second lens group GR2 and the third lens group GR3 are more complex, the lens elements are more, and finally the imaging quality is degraded and the lens structure is too complex and heavy;

when the ratio of the combined focal length of the first lens group GR1 to the focal length of the lens is higher than the upper limit of the condition (1), the total length of the lens is too long, the lens structure is too complex and heavy, which is not favorable for the miniaturization of the lens, and the portability is poor.

In a specific embodiment of the present embodiment, the first lens group GR1 has an F-number of 1.6 to 2.2 and a field angle of 55 to 75 degrees, can be used as a large-aperture single focus lens in an interchangeable lens apparatus, and can be applied to a camera device having an interchangeable lens, such as a camera, a video camera, a digital camera, and a broadcasting camera.

Referring to fig. 1 and 6, in an embodiment of the present application, the first lens group GR1 includes a first negative lens G disposed sequentially along an optical axis from an object side to an image side₁₁A second positive lens G₁₂A third negative lens G₁₃A fourth positive lens G₁₄And a fifth positive lens G₁₅First negative lens G₁₁Satisfies the condition (2):

0.5≤(R₁₁+R₁₂)/(R₁₁-R₁₂)≤3，

wherein R is₁₁Denotes a radius of curvature, R, of a surface of the first negative lens G11 facing the object side₁₂Denotes a first negative lens G₁₁The curvature radius of the surface opposite to the image side.

Essentially, condition (2) defines the first negative lens G₁₁The focal length range of (1), the first negative lens G satisfying the condition₁₁Has enough negative power to counteract the positive power of other lenses in the first lens group GR1, reducing chromatic aberration of the lenses; meanwhile, the positive focal power of the first lens group GR1 is not too small, and the lens does not need to be arranged very long, which is beneficial to the miniaturization of the lens.

If the first negative lens G₁₁The ratio of the sum of the radii of curvature of both surfaces to the difference between the radii of curvature of both surfaces is less than the lower limit of the condition (2), and the first negative lens G₁₁In this case, the positive power of the first lens group GR1 is too small, and the total length of the lens needs to be set longer, which is not favorable for miniaturization and portability of the lens;

if the first negative lens G₁₁The ratio of the sum of the radii of curvature of both faces to the difference between the radii of curvature of both faces being higher than the upper limit of the condition (2) results in the first negative lens G₁₁The negative focal power is too small, which means that the positive focal power of the first lens group GR1 is too high, and the refractive power difference of the light rays in each wavelength band is too large, so that the chromatic aberration of magnification is increased, and the imaging quality of the whole lens is affected.

Referring to fig. 1 and 6, in an embodiment of the present application, the lens further includes a stop SP, and the stop SP is coaxial with the lens and disposed on the fourth positive lens G₁₄And a fifth positive lens G₁₅In the meantime.

In one embodiment of the present application, the fourth positive lens G₁₄Satisfies the condition (3):

60≤ν_d4≤90，

wherein, v_d4Denotes a fourth positive lens G₁₄Abbe number of (2).

Condition (3) specifies the fourth positive lens G in the first lens group GR1₁₄Abbe number of (1), fourth positive lens G₁₄The dispersion coefficient of (b) determines the degree of correction of positional chromatic aberration and chromatic aberration of magnification of the first lens group GR1, and is an important factor affecting imaging performance. A fourth positive lens G₁₄The abbe number of (b) is limited to 60 to 90, so that the production cost of the lens can be reduced without affecting the performance of the lens.

Specifically, if the fourth positive lens G₁₄Is lower than the lower limit of conditional expression (3), the fourth positive lens G₁₄The capability of correcting the two chromatic aberrations is weak, which is not beneficial to correcting the chromatic aberration of the whole imaging lens; if the fourth positive lens G₁₄Has an Abbe number of 90 or more, is higher than the upper limit of conditional expression (3), and is extremely expensive because of having an Abbe number of more than 90, and therefore, the fourth positive lens G is produced using a material having an Abbe number of 90 or more₁₄The cost of the lens is increased and the correction performance is excessive.

It is to be understood that the abbe number as described in all the embodiments of the present application refers to the abbe number of the lens material with respect to the d-line (wavelength 587.56 nm), in particular v_d＝(n_d-1)/(n_F-n_C) Wherein n is_dIs the refractive index of the medium to light of 587.56nm, n_FIs the refractive index of the medium for light of 486.13nm, n_CIs the refractive index of the medium for 656.27nm light.

In one embodiment of the present application, the fifth positive lens G₁₅Satisfies the condition (4):

1.8≤n_d≤2.0，

wherein n is_dDenotes a fifth positive lens G₁₅Is used as a refractive index of (1).

Conditional expression (4) specifies the fifth positive lens G of the first lens group GR1₁₅The refractive index range of the material is selected. If the fifth positive lens G₁₅Is higher than the upper limit of the condition (4), the fifth positive lens G₁₅The focal power of the first lens group GR1 is too large, the magnification chromatic aberration moves to the positive direction, the correction capability of the first lens group GR1 on the magnification chromatic aberration is insufficient, and the imaging quality of the position far away from the imaging center is low; if the fifth positive lens G₁₅Is lower than the lower limit of the condition (4), the fifth positive lens G₁₅Too small, the distortion moves in the direction of barrel distortion, and the first lens group GR1 has insufficient correction capability for barrel distortion, which also results in poor image quality at a position away from the image center.

Referring to fig. 1 and 6, in one embodiment of the present application, the second lens group GR2 includes an achromatic lens group G disposed in order from an object side to an image side along an optical axis₂₁And an eighth positive lens G₂₂Achromatic lens group G₂₁Including a sixth closely fitted positive lens G_j1And a seventh negative lens G_j2Sixth positive lens G_j1And a seventh negative lens G_j2Satisfies the condition (5):

nd_j1≤nd_j2；vd_j1≥vd_j2，

therein, nd_j1And nd_j2Respectively, a sixth positive lens G_j1And a seventh negative lens G_j2Refractive index of (a), vd_j1And vd_j2Respectively, a sixth positive lens G_j1And a seventh negative lens G_j2Abbe number of (2).

Conditional expressions (5) respectively specify the achromatic lens groups G₂₁The sixth positive lens G in (1)_j1And a seventh negative lens G_j2The sixth positive lens G satisfying the condition (5) regarding the relationship between the refractive index and Abbe number of the material of (3)_j1And a seventh negative lens G_j2Achromatic lens group G of composition₂₁The chromatic aberration can be reduced, the spherical aberration can be reduced obviously, and the imaging quality of the lens can be improved obviously.

In one embodiment of the present application, the eighth positive lens G₂₂An aspherical lens is used, and an eighth positive lens G₂₂Satisfies the condition (6):

1.70≤n_d8≤1.90；40≤ν_d8≤70，

wherein n is_d8Denotes an eighth positive lens G₂₂Refractive index of (v)_d8Denotes an eighth positive lens G₂₂Abbe number of (2).

The conditional expressions (6) define eighth positive lenses G₂₂Refractive index and Abbe number of the eighth positive lens G₂₂Is lower than the lower limit of the over-condition (6) because of the eighth positive lens G₂₂Has too low refractive index and Abbe number, and an eighth positive lens G₂₂The requirement of the lens on the correction effect of the spherical aberration cannot be met, and the spherical aberration of the whole system cannot be balanced; if the eighth positive lens G₂₂When the refractive index and Abbe number of (G) are higher than the upper limit of the condition (6), the high refractive index glass is soft, and the eighth positive lens G₂₂The material of the lens is difficult to form, and the processing and manufacturing process of the lens are required to be too high, so that the production cost of the lens is too high.

In one embodiment of the present application, the third lens group GR3 satisfies condition (7):

-1.5≤F₃/F≤-0.7，

wherein, F₃Denotes a focal length of the third lens group GR 3.

The condition (7) specifies the incident angle of light rays of the third lens group GR3, and the negative lens satisfying the condition (7) is used to form the third lens group GR3, which enables the imaging quality of the lens barrel to be optimized. If the ratio of the focal length of the third lens group GR3 to the focal length of the lens is higher than the upper limit specified in condition (7), the focal power of the third lens group GR3 becomes too large, and as a result, the third lens group GR3 generates too large negative spherical aberration, and the negative spherical aberration of the lens becomes too large to be corrected; on the other hand, if the ratio of the focal length of the third lens group GR3 to the focal length of the lens is lower than the lower limit specified in condition (7), the focal power of the negative lens becomes too small, so that negative spherical aberration becomes too small, and the positive spherical aberration becomes excessive. Both of the above conditions affect the imaging quality of the lens.

Referring to fig. 1 and fig. 6, as a specific solution of the present embodiment, the third lens group GR3 includes a ninth negative lens G₃₁Ninth negative lens G₃₁The condition (7) is satisfied.

In one embodiment of the present application, the lens satisfies condition (8):

0.3≤B_f/F≤0.7，

wherein, B_fRepresenting the distance between the lens surface of the lens closest to the image plane IMG and the image plane IMG.

The conditional expression (8) specifies the ratio of the distance between the lens surface of the lens closest to the image plane IMG and the image plane IMG to the focal length of the lens, the lens conforming to the conditional expression (8) has excellent optical performance, and the ratio of the rear intercept of the lens to the focal length of the lens is moderate, so that the lens is suitable for cameras with interchangeable imaging lenses, such as micro single cameras.

Specifically, if the ratio of the distance between the lens surface of the lens closest to the image plane IMG and the image plane IMG to the focal length of the lens is below the lower limit specified by condition (8), the back intercept becomes too short with respect to the focal length of the lens, so that it becomes difficult to obtain a lens suitable for use in a micro-single camera; if the ratio of the distance between the lens surface closest to the image plane IMG and the focal length of the lens is higher than the upper limit specified by the condition (8), the back intercept becomes relatively too long with respect to the focal length of the lens, and strong curvature of field exists, so that it is difficult to correct distortion, which affects the final imaging quality of the lens.

Another object of the present application is to provide an image pickup apparatus including the lens barrel in the foregoing embodiment.

The technical effects of the lens provided by the present application are described in several specific embodiments as follows:

example one

Referring to fig. 1, in the present embodiment, a lens includes a first lens group GR1 and a second lens group GR2 having positive power, which are disposed in order from an object side to an image side along an optical axis, and a third lens group GR3 having negative power, and the first lens group GR1 includes a first negative lens G disposed in order from the object side to the image side along the optical axis₁₁The first stepTwo positive lens G₁₂A third negative lens G₁₃A fourth positive lens G₁₄And a fifth positive lens G₁₅The second lens group GR2 includes a sixth positive lens G disposed in order from the object side to the image side along the optical axis_j1The seventh negative lens G_j2And an eighth positive lens G₂₂Sixth positive lens G_j1And a seventh negative lens G_j2Closely attached, eighth positive lens G₂₂The third lens group GR3 includes a ninth negative lens G which is an aspherical lens₃₁. The lens barrel provided by the embodiment has the second lens group GR2 moving along the optical axis during focusing, and the first lens group GR1 and the third lens group GR3 fixed relative to the image plane.

Referring to fig. 1, in the present embodiment, optionally, a parallel glass plate GL is disposed between the negative lens of the third lens group GR3 and the image plane IMG, and a filter layer is disposed on a surface of the parallel glass plate GL for protecting the color sensor disposed on the image plane IMG.

Hereinafter, each numerical value data regarding the imaging lens of the present embodiment is shown.

The following table shows basic data of the lens:

aspherical surface data of the lens barrel of example one (eighth positive lens G)₂₂Surface parameters) were as follows:

fig. 2 to 5 show imaging parameters of the lens provided in this embodiment when focusing on an object far from the lens and when focusing in a near field, where fig. 2 is a graph illustrating a variation trend of longitudinal aberration when focusing on an object far from the lens; fig. 3 is a graph of the variation trend of curvature of field and distortion when the lens provided by the embodiment focuses on an object far away from the lens; fig. 4 is a trend chart of the longitudinal aberration when the lens provided by the present embodiment is focused at 0.35 meters; fig. 5 is a graph of the variation trend of curvature of field and distortion when the lens provided by the present embodiment is focused at 0.35 meters. It can be seen that the lens provided by the embodiment can effectively eliminate longitudinal aberration, curvature of field and distortion at each imaging distance, has small chromatic aberration, and especially has excellent near-field portrait photographing effect.

Example two

Referring to fig. 6, the present embodiment is a parallel scheme of the first embodiment, and the actual configuration of the lens is the same as that of the lens in the first embodiment, but the difference is the specific parameter setting of the lens, specifically, the numerical data of the lens provided in the present embodiment are as follows.

Basic data of the lens provided in the present embodiment are as follows

Aspherical surface data of the lens barrel of example two (eighth positive lens G)₂₂Surface parameters) were as follows:

fig. 7 to 10 show imaging parameters of the lens provided in this embodiment when focusing on an object far from the lens and when focusing in a near field, where fig. 7 is a graph illustrating a variation trend of longitudinal aberration when focusing on an object far from the lens; fig. 8 is a graph showing the variation trend of curvature of field and distortion when the lens provided by the present embodiment is focused on an object far from the lens; fig. 9 is a trend graph of the longitudinal aberration when the lens provided by the present embodiment is focused at 0.35 meters; fig. 10 is a graph of the variation trend of curvature of field and distortion when the lens provided by the present embodiment is focused at 0.35 meters. It can be seen that the lens provided by the embodiment can effectively eliminate longitudinal aberration, curvature of field and distortion at each imaging distance, has small chromatic aberration, and especially has excellent near-field portrait photographing effect.

The lenses provided in the first and second embodiments both satisfy the above conditions, and the following table specifically refers to:

it should be noted that the specific parameters in the above table are merely exemplary, and the parameters of each lens are not limited to the values shown in the above numerical embodiments, and other values may be adopted, and similar or identical technical effects may be achieved.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (10)

1. A lens barrel includes a first lens group and a second lens group having positive power, and a third lens group having negative power, the first lens group, the second lens group, and the third lens group being arranged in order along an optical axis from an object side to an image side;

the first lens group and the third lens group are fixed with respect to an image plane and the second lens group moves to the object side upon zooming from infinity to close of the lens;

the focal length of the lens and the focal length of the first lens group satisfy:

1≤F₁/F≤2，

wherein F represents the focal length of the lens, and F₁Representing a combined focal length of the first lens group.

2. The lens barrel according to claim 1, wherein the first lens group includes a first negative lens, a second positive lens, a third negative lens, a fourth positive lens, and a fifth positive lens arranged in this order from the object side to the image side along the optical axis, the first negative lens satisfying:

0.5≤(R₁₁+R₁₂)/(R₁₁-R₁₂)≤3，

wherein R is₁₁Represents a radius of curvature, R, of a surface of the first negative lens facing the object side₁₂And the curvature radius of the surface of the first negative lens, which is opposite to the image side, is shown.

3. The lens barrel according to claim 2, further comprising a diaphragm coaxial with the lens and disposed between the fourth positive lens and the fifth positive lens.

4. The lens barrel as recited in claim 2, wherein the fourth positive lens satisfies:

60≤ν_d4≤90，

wherein, v_d4Represents an abbe number of the fourth positive lens.

5. The lens barrel as recited in claim 2, wherein the fifth positive lens satisfies:

1.8≤n_d≤2.0，

wherein n is_dRepresents a refractive index of the fifth positive lens.

6. The lens barrel according to claim 1, wherein the second lens group includes an achromatic lens group and an eighth positive lens in order from the object side to the image side along the optical axis, the achromatic lens group includes a sixth positive lens and a seventh negative lens which are closely attached, and the sixth positive lens and the seventh negative lens satisfy:

nd_j1≤nd_j2；vd_j1≥vd_j2，

therein, nd_j1And nd_j2Respectively represent refractive indexes, vd, of the sixth positive lens and the seventh negative lens_j1And vd_j2Abbe numbers of the sixth positive lens and the seventh negative lens are respectively expressed.

7. The lens barrel as claimed in claim 6, wherein the eighth positive lens is an aspherical lens, and the eighth positive lens satisfies:

1.70≤n_d8≤1.90；40≤ν_d8≤70，

wherein n is_d8Denotes a refractive index, v, of the eighth positive lens_d8Represents an abbe number of the eighth positive lens.

8. The lens barrel according to claim 1, wherein the third lens group satisfies:

-1.5≤F₃/F≤-0.7，

wherein, F₃Denotes a focal length of the third lens group.

9. A lens barrel as claimed in any one of claims 1 to 8, wherein the lens barrel satisfies:

0.3≤B_f/F≤0.7，

wherein, B_fRepresenting the distance between the lens surface of the lens closest to the image plane and the image plane.

10. An image pickup apparatus comprising the lens barrel according to any one of claims 1 to 9.

Images