JP2005274663A - Zoom lens with synthetic resin lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a low-cost compact zoom optical system which meets high pixels and is suitable for being mounted in, especially, a small information terminal device. <P>SOLUTION: The zoom lens comprises, in order of object side, the first group 11 that is negative, the second group 12 that is positive, and the third group 13 that is positive. The first group 11 and the second group 12 move for zooming. The first group 11 is composed of: the first lens G1 which has an aspherical face and has a negative refracting power; and the second lens G2 which has a positive refracting power. The second group 12 is composed of: the third lens G3 made of glass, which has an spherical face, whose convex face faces in the direction of the object side near the optical axis, and which has a positive refracting power; the fourth lens G4 which has a negative refracting power and whose both sides are concave; and the fifth lens G5. The third group 13 is composed of only the sixth lens G6 which has a positive refracting power and whose both sides are convex. At least the first lens G1 or the sixth lens G6 is a synthetic resin lens. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a zoom lens having a synthetic resin lens (plastic lens) suitable for mounting on a small information terminal device such as a camera-equipped mobile phone or a PDA (Personal Digital Assistant).

  In recent years, with the spread of personal computers to ordinary homes and the like, digital still cameras (hereinafter simply referred to as digital cameras) capable of inputting image information such as photographed landscapes and human images to personal computers have rapidly spread. It's getting on. As mobile phones become more sophisticated, camera-equipped mobile phones equipped with a small imaging module are also rapidly spreading. In addition, small information terminal devices such as PDAs that are equipped with an imaging module have become widespread.

  In devices equipped with these imaging functions, imaging devices such as a charge coupled device (CCD) and a complementary metal oxide semiconductor (CMOS) are used. In recent years, these image sensors have been extremely reduced in size and increased in pixels, and accordingly, the main body of the image pickup apparatus and the lens mounted thereon are also required to have a compact configuration with high resolution performance. Yes. For example, camera-equipped mobile phones and the like that are compatible with megapixels of 1 million pixels or more have been put into practical use, and the demand for performance has been increasing.

  By the way, there are an optical zoom method and an electronic zoom method as a method for realizing a zoom function in an imaging device using an image sensor. In the optical zoom system, a zoom lens is mounted as a photographing lens, and the photographing magnification is optically changed. The electronic zoom method electronically changes the size of a subject image by trimming an image by signal processing. In general, the optical zoom method can obtain higher resolution performance than the electronic zoom method. Therefore, when zooming with high resolution performance, the optical zoom method is preferable.

Conventionally, as a relatively small zoom lens used for a digital camera or the like, for example, there is a lens described in Patent Document 1 below. Patent Document 1 describes a zoom lens of a two-group zoom system that is composed of five or six lenses as a whole.
JP 2003-270533 A

  In small information terminal devices such as camera-equipped mobile phones, conventionally, fixed-focus lenses are generally used in terms of cost and miniaturization, but with the recent increase in functionality and multifunction, There is a demand for a zoom function. Therefore, recently, some mobile phones with cameras using fixed focus lenses have realized a zoom function by adopting an electronic zoom method. However, in the case of the electronic zoom method, the resolution deteriorates as the image enlargement ratio increases, and it has become difficult to cope with the recent increase in the number of pixels of the image sensor.

  Therefore, it is conceivable that a camera-equipped mobile phone or the like is equipped with a zoom lens and adopts an optical zoom system. In this case, using a high-performance zoom lens developed for a conventional digital camera as it is is not practical in terms of cost and compactness. Although the zoom lens described in Patent Document 1 is also reduced in size with a relatively small number of lenses for a digital camera, it is further reduced in size when used in a small information terminal device. It is preferable that the cost is reduced. On the other hand, a low-cost and compact zoom lens composed of about three lenses has been developed in the past, but this makes it difficult to cope with an increase in the number of pixels.

  The present invention has been made in view of such problems, and an object of the present invention is to realize a low-cost and compact zoom optical system that is suitable for mounting in a small information terminal device, while corresponding to an increase in the number of pixels. Another object is to provide a zoom lens having a synthetic resin lens.

  A zoom lens having a synthetic resin lens according to the present invention includes, in order from the object side, a first group having a negative refractive power, a second group having a positive refractive power, and a third group having a positive refractive power. And the first group and the second group move on the optical axis during zooming. The first group includes, in order from the object side, a first lens having a negative refractive power having an aspheric surface and a second lens having a positive refractive power. The second group includes, in order from the object side, a third lens made of glass having a positive refractive power and an aspherical surface with a convex surface facing the object side in the vicinity of the paraxial axis, and a biconcave first lens having a negative refractive power. It consists of four lenses and a fifth lens. The third group includes only one biconvex sixth lens having positive refractive power. In addition, at least one of the first lens and the sixth lens is made of a synthetic resin lens. Furthermore, it is comprised so that the following conditional expressions may be satisfied.

4.0 <Tw / fw <5.5 (1)
1.1 <f2g / fw <1.6 (2)
Where fw is the focal length of the entire system at the wide-angle end, Tw is the conjugate distance (full length) at the wide-angle end, and f2g is the focal length of the second group.

In this zoom lens, the fifth lens is a lens made of synthetic resin having an aspherical surface, has a meniscus shape with a convex surface facing the object side in the vicinity of the paraxial axis, and is configured to satisfy the following conditional expression: Preferably it is.
| Fw / fg5 | <15 (2-2)
Here, fg5 indicates the focal length of the fifth lens.

This zoom lens is also preferably configured to satisfy the following conditional expression.
| F3 / ν3 + f4 / ν4 | / fw <0.06 (3)
0.4 <DG4 / fw <0.7 (4)
Where f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, ν3 is the Abbe number of the third lens, and ν4 is the Abbe number of the fourth lens. DG4 indicates the center thickness of the fourth lens.

  In this zoom lens, it is preferable that both the first lens and the third lens are aspheric on both surfaces, and the first lens is a lens made of synthetic resin. In this case, the sixth lens is preferably a synthetic resin lens.

  In the zoom lens according to the present invention, zooming is performed by moving the first group and the second group on the optical axis. Focus adjustment may be performed in the third group, but fixing the third group during zooming and focus adjustment is advantageous in terms of reducing the number of moving groups, and also provides mechanical strength and robustness. This is preferable because it is advantageous in terms of sex. When the third group is a fixed group, the focus adjustment can be performed, for example, by moving the first group alone or the first group and the second group to the front side during short-distance shooting.

  In this zoom lens, as a three-group six-lens configuration, for example, by increasing the number of lenses as compared with the zoom lens having the five-lens configuration described in Patent Document 1, a brighter performance can be obtained, and aberrations can be improved. It has been corrected. In addition, cost reduction is achieved by using a lens made of synthetic resin. In order to further shorten the overall length, an aspheric lens is used. In addition to these, particularly by satisfying conditional expressions (1) and (2) and appropriate power distribution, a compact optical system having a short overall length is realized. Furthermore, by appropriately adopting the above-described preferable conditions as necessary, it is further advantageous for correction of aberrations, and a high-performance zoom optical system corresponding to an increase in the number of pixels can be obtained.

  According to the zoom lens having the synthetic resin lens according to the present invention, the aspherical lens and the synthetic resin lens are appropriately used as the three-group / six-element configuration, and power distribution and the like are appropriate while satisfying each conditional expression. As a result, it is possible to realize a low-cost and compact zoom optical system that is suitable for mounting on a small information terminal device, while accommodating high pixels.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1A and 1B show a configuration example of a zoom lens according to an embodiment of the present invention. This configuration example corresponds to the lens configuration of a first numerical example (FIGS. 2A and 2B) described later. 1A shows the lens arrangement at the wide-angle end, and FIG. 1B shows the lens arrangement at the telephoto end.

  In FIG. 1 (A), the reference symbol Ri is attached so that the surface of the constituent element closest to the object side including the aperture stop St is first, and sequentially increases toward the image side (imaging side). The curvature radius of the i-th (i = 1 to 15) surface is shown. The symbol Di indicates the surface interval on the optical axis Z1 between the i-th surface and the i + 1-th surface.

  This zoom lens is particularly suitable for mounting on an imaging device using a small imaging device, for example, a small information terminal device such as a mobile phone with a camera. This zoom lens includes a first group 11 having a negative refractive power, a second group 12 having a positive refractive power, and a third group 13 having a positive refractive power along the optical axis Z1. Yes. On the object side of the second group 12, an aperture stop St is provided.

  An imaging element such as a CCD (not shown) is disposed on the imaging surface (imaging surface) Simg of the zoom lens. Various optical members may be arranged between the third lens group 13 as the final lens group and the imaging surface Simg depending on the configuration of the camera side on which the lens is mounted. In the illustrated configuration example, a cover glass GC for protecting the imaging surface Simg is disposed. In addition, an optical member such as an infrared cut filter or a low-pass filter may be disposed.

  This zoom lens is a two-group zoom system, and zooming is performed by moving the first group 11 and the second group 12 on the optical axis. As the first group 11 and the second group 12 are zoomed from the wide-angle end to the telephoto end, the first group 11 and the second group 12 move so as to draw a locus indicated by a solid line in FIGS. 1 (A) and 1 (B). The focus adjustment is performed in the third group 13, for example. However, the third group 13 may be a fixed group, and focus adjustment may be performed by, for example, extending the first group 11 alone or both the first group 11 and the second group 12 forward during close-up shooting. .

  The first group 11 includes a first lens G1 and a second lens G2. The first lens G1 is composed of an aspheric lens having at least one aspheric surface and has negative refractive power. When the first lens G1 is a double-sided aspherical surface, it is preferably composed of a synthetic resin lens. The first lens G1 has, for example, a biconcave shape in the vicinity of the paraxial. The second lens G2 has a positive refractive power. The second lens G2 is, for example, a positive meniscus spherical lens with a convex surface facing the object side.

  The second group 12 includes a third lens G3, a fourth lens G4, and a fifth lens G5. The third lens G3 is a glass aspheric lens having at least one aspheric surface. The third lens G3 has a positive refractive power, has a convex surface facing the object side in the vicinity of the paraxial axis, and has, for example, a biconvex shape. The image-side surface of the third lens G3 has, for example, a shape having a curvature with a sign different from that in the vicinity of the paraxial as it goes to the periphery, that is, a convex shape on the image side in the vicinity of the paraxial and a concave shape as it goes to the periphery. It is preferable. The fourth lens G4 is a biconcave spherical lens having negative refractive power.

  The fifth lens G5 is, for example, a synthetic resin lens having at least one aspheric surface. The fifth lens G5 has, for example, a meniscus shape with a convex surface facing the object side in the vicinity of the paraxial.

  The third group 13 includes only a sixth lens G6. The sixth lens G6 has a positive refractive power and is a biconvex spherical lens. The sixth lens G6 is preferably a synthetic resin lens.

This zoom lens is configured to satisfy the following conditional expressions (1) and (2). Where fw is the focal length of the entire system at the wide-angle end, Tw is the conjugate distance (full length) at the wide-angle end, and f2g is the focal length of the second group 12.
4.0 <Tw / fw <5.5 (1)
1.1 <f2g / fw <1.6 (2)

Regarding conditional expression (2), it is further preferable to be in the following numerical range.
1.1 <f2g / fw <1.3 (2A)

The zoom lens is preferably configured to satisfy at least one of the following conditional expressions with respect to the second group 12. Here, fg5 indicates the focal length of the fifth lens G5. f3 is the focal length of the third lens G3, f4 is the focal length of the fourth lens G4, ν3 is the Abbe number of the third lens G3, and ν4 is the Abbe number of the fourth lens G4. DG4 indicates the center thickness of the fourth lens G4.
| Fw / fg5 | <15 (2-2)
| F3 / ν3 + f4 / ν4 | / fw <0.06 (3)
0.4 <DG4 / fw <0.7 (4)
Regarding conditional expression (3), it is more preferable that the following numerical range be satisfied.
| F3 / ν3 + f4 / ν4 | / fw <0.03 (3A)

It is preferable that the zoom lens is further configured to satisfy the following conditional expression with respect to the second group 12 and the third group 13. f5 is the focal length of the fifth lens G5, f6 is the focal length of the sixth lens G6, ν5 is the Abbe number of the fifth lens G5, and ν6 is the Abbe number of the sixth lens G6.
65 <| ν3 / f3 + ν4 / f4 + ν5 / f5 + ν6 / f6 | × fw <75 (5)

  Next, operations and effects of the zoom lens configured as described above will be described.

  In this zoom lens, zooming is performed by moving the first group 11 and the second group 12 on the optical axis. Focus adjustment may be performed by the third group 13, but fixing the third group 13 during zooming and focus adjustment is advantageous in terms of reducing the number of moving groups, and mechanical strength. It is preferable because it is advantageous in terms of fastness. Further, it is preferable to move both the first group 11 and the second group 12 as the focus group because the movement amount of each group can be reduced. In this case, it is preferable to make the power of the first group 11 and the power of the second group 12 relatively stronger than the power of the third group 13 because the amount of movement during zooming and focusing can be reduced.

  In this zoom lens, the effective aperture of the first group 11 is made smaller by arranging the aperture stop St relatively on the front side, that is, on the front side of the third lens G3, compared to the case where it is arranged on the rear side. The entire lens is downsized.

  In this zoom lens, the number of lenses is increased as compared with the zoom lens having a five-lens configuration described in Patent Document 1 (Japanese Patent Laid-Open No. 2003-270533), for example. And aberrations are corrected well. In addition, cost reduction is achieved by using a lens made of synthetic resin. Synthetic resin lenses have a greater change in optical properties due to temperature than glass lenses. In particular, focus shift and image plane fluctuation due to temperature changes are problematic. In this zoom lens, at least one of the negative first lens G1 or the positive sixth lens G6 is a lens made of synthetic resin, but it is more positive than only one lens made of synthetic resin. It is preferable to use two negative lenses made of synthetic resin because temperature compensation is performed and the amount of focus movement can be reduced. By the way, in the case of a small photographic lens, recently, it has become possible to independently and freely control a plurality of moving groups by a small actuator using a piezo element as a moving mechanism. Therefore, even if there is a change in the optical characteristics due to temperature, for example, it is relatively easy to control the movement of the first group 11 and the second group 12 so as to correct the change. Even if you use a lot, it doesn't matter so much.

  Also, in this zoom lens, by using many aspheric lenses, the total length is shortened while correcting aberrations well. In addition to these, by satisfying each conditional expression and making power distribution appropriate, the overall length is shorter and more compact than the zoom lens described in Patent Document 1, and high performance corresponding to an increase in the number of pixels is achieved. A zoom optical system can be obtained.

  Conditional expression (1) relates to the total length of the lens system. If the lower limit of conditional expression (1) is exceeded and the total length is made too short, it will be difficult to maintain the performance particularly at the telephoto end. If the upper limit of conditional expression (1) is exceeded, the performance is improved, but the overall length becomes too long and the market competitiveness when actually commercialized is lost.

  Conditional expression (2) relates to the power of the second group 12 which is the rear movement group of the two zoom movement groups. It is preferable to satisfy the conditional expression (2) and make the power of the second group 12 relatively strong because the overall length can be easily shortened.

  Conditional expression (2-2) relates to the power of the fifth lens G5, which is the final lens in the second group 12. In particular, when the fifth lens G5 is a synthetic resin lens, the amount of focus movement and the amount of fluctuation of the image plane due to temperature change can be reduced by satisfying the conditional expression (2-2) and reducing the power relatively. Therefore, it is preferable.

  Conditional expression (3) relates to the achromatic condition of the positive third lens G3 and the negative fourth lens G4 in the second group 12. By selecting an appropriate glass material so as to satisfy the conditional expression (3), good achromaticity can be performed inside the second group 12.

  Conditional expression (4) defines an appropriate range of the center thickness of the fourth lens G4. By setting the center thickness to an appropriate value so as to satisfy the conditional expression (4), it is possible to reduce fluctuations in the image plane during zooming, and in particular, it is possible to maintain a favorable image plane position in the intermediate range. It is also advantageous for reducing the axial chromatic aberration. Further, if the center thickness becomes too thin beyond the lower limit of conditional expression (4), the front principal point position of the entire second group 12 including the fourth lens G4 moves backward, particularly in the first group at long focus. Since the space | interval between 11 and the 2nd group 12 will become enough, it is not preferable.

  Conditional expression (5) relates to the condition of the Abbe number of each lens in the second group 12 and the third group 13. By selecting an appropriate glass material so as to satisfy this condition, it is possible to satisfy good performance equivalent to that when a cemented lens is used with respect to chromatic aberration. Furthermore, it is advantageous for reducing the overall length.

  As described above, according to the present embodiment, a low-cost and compact size that is suitable for mounting on a small information terminal device while effectively using a synthetic resin lens and corresponding to an increase in the number of pixels. A zoom optical system can be realized.

  Next, specific numerical examples of the zoom lens according to the present embodiment will be described. Hereinafter, the first and second numerical examples (Examples 1 and 2) will be described together. FIGS. 2A and 2B show a first numerical example, and show specific lens data corresponding to the cross-sectional configuration of the zoom lens shown in FIGS. 1A and 1B. 3A and 3B show a second numerical example. The cross-sectional configuration of the zoom lens according to Example 2 is similar to that shown in FIGS. 2A and 3A show basic data portions of the lens data of the embodiment, and FIGS. 2B and 3B show the embodiment of the embodiment. The data part regarding an aspherical shape is shown among lens data.

  In the column of the surface number Si in each lens data of FIGS. 2A and 3A, the surface of the most object side component including the aperture stop St and the cover glass GC is shown for the zoom lens of each embodiment. First, the number of the i-th (i = 1 to 15) surface, which is added so as to increase sequentially toward the image side, is shown. In the column of the curvature radius Ri, the value of the curvature radius of the i-th surface from the object side is shown in correspondence with the symbol Ri attached in FIG. The column of the surface interval Di also indicates the interval on the optical axis between the i-th surface Si and the i + 1-th surface Si + 1 from the object side, corresponding to the reference numerals in FIG. The unit of the value of the curvature radius Ri and the surface interval Di is millimeter (mm). In the columns Ndj and νdj, the refractive index for the d-line (587.6 nm) and the Abbe number of the j-th (j = 1 to 7) optical element from the object side including the cover glass GC are shown.

  In each of the zoom lenses according to the embodiments, the first group 11 and the second group 12 move on the optical axis with zooming. Therefore, the front and back surface distances D4 and D11 of these groups are variable. ing. In the lens data of FIGS. 2A and 3A, the maximum value and the minimum value are described as the values of these variable surface distances D4 and D11.

  As shown in FIG. 2A, in the zoom lens according to Example 1, the first lens G1, the fifth lens G5, and the sixth lens G6 are lenses made of synthetic resin. As shown in FIG. 3A, in the zoom lens according to Example 2, the first lens G1 and the fifth lens G5 are lenses made of synthetic resin.

  In each lens data shown in FIGS. 2A and 3A, the symbol “*” attached to the left side of the surface number indicates that the lens surface is aspherical. In the zoom lenses of Examples 1 and 2, both surfaces S1 and S2 of the first lens G1, both surfaces S6 and S7 of the third lens G3, and both surfaces S10 and S11 of the fifth lens G5 are aspherical. In the basic lens data in FIGS. 2A and 3A, numerical values of the radius of curvature near the optical axis (near the paraxial axis) are shown as the radius of curvature of these aspheric surfaces.

In the numerical values of the respective aspherical data shown in FIG. 2B and FIG. 3B, the symbol “E” indicates that the subsequent numerical value is a “power index” with 10 as the base, A numerical value represented by an exponential function with a base of 10 is multiplied by a numerical value before “E”. For example, “1.0E-02” indicates “1.0 × 10 ⁻² ”.

In each aspheric surface data, the values of the coefficients A _i and KA in the aspheric surface expression represented by the following expression (A) are described. More specifically, Z is the length (mm) of a perpendicular line drawn from a point on the aspheric surface at a height h from the optical axis to the tangential plane (plane perpendicular to the optical axis) of the apex of the aspheric surface. Show.

Z = C · h ² / {1+ (1−KA · C ² · h ² ) ^1/2 } + ΣA _i · h ⁱ (A)
However,
Z: Depth of aspheric surface (mm)
h: Distance from the optical axis to the lens surface (height) (mm)
KA: eccentricity C: paraxial curvature = 1 / R
(R: paraxial radius of curvature)
A _i : i-th (i = 3 to 10) aspheric coefficient

As shown in FIG. 2B, in the zoom lens according to Example 1, both surfaces S1 and S2 of the first lens G1 have not only even-order terms but also odd-order terms as aspheric coefficients A _i. Also, both surfaces S6 and S7 of the third lens G3 and both surfaces S10 and S11 of the fifth lens G5 are configured using only even-order terms effectively. As shown in FIG. 3B, in the zoom lens according to Example 2, both surfaces S1 and S2 of the first lens G1 and both surfaces S10 and S11 of the fifth lens G5 are even-order as aspheric coefficients A _i. In addition to this term, odd-order terms are also used effectively, and both surfaces S6 and S7 of the third lens G3 are configured using only even-order terms effectively.

  FIG. 4 collectively shows values relating to the above-described conditional expressions for the respective examples. As shown in FIG. 4, the values of the respective examples are within the numerical ranges of the conditional expressions (1), (2), (2-2), and (3) to (5). In Example 1, the numerical range of the conditional expression (2A) is further satisfied.

  5A to 5C show spherical aberration, astigmatism, and distortion (distortion aberration) at the wide angle end in the zoom lens of Example 1. FIG. 6A to 6C show similar aberrations at the telephoto end. Each aberration diagram shows an aberration with a wavelength of 540 nm as a reference wavelength, while the spherical aberration diagram and the astigmatism diagram also show aberrations for wavelengths of 420 nm and 680 nm. In the astigmatism diagram, the solid line indicates the sagittal direction and the broken line indicates the tangential direction. FNO. Indicates an F value, and ω indicates a half angle of view.

  Similarly, various aberrations for Example 2 are shown in FIGS. 7A to 7C (wide-angle end) and FIGS. 8A to 8C (telephoto end).

  As can be seen from the numerical data and aberration diagrams, a compact and high-performance zoom optical system suitable for mounting on a small information terminal device can be realized in each embodiment.

  In addition, this invention is not limited to the said embodiment and each Example, A various deformation | transformation implementation is possible. For example, the radius of curvature, the surface interval, and the refractive index of each lens component are not limited to the values shown in the above numerical examples, and may take other values.

1 is a lens cross-sectional view illustrating a configuration example of a zoom lens according to an embodiment of the present invention and corresponding to Example 1. FIG. 6 is a diagram illustrating lens data of a zoom lens according to Example 1. FIG. 7 is a diagram illustrating lens data of a zoom lens according to Example 2. FIG. It is a figure which shows the value regarding the conditional expression which the zoom lens concerning each Example satisfy | fills. FIG. 6 is an aberration diagram illustrating spherical aberration, astigmatism, and distortion at the wide angle end of the zoom lens according to Example 1; FIG. 6 is an aberration diagram illustrating spherical aberration, astigmatism, and distortion at the telephoto end of the zoom lens according to Example 1; FIG. 6 is an aberration diagram illustrating spherical aberration, astigmatism, and distortion at the wide angle end of the zoom lens according to Example 2; FIG. 6 is an aberration diagram illustrating spherical aberration, astigmatism, and distortion at the telephoto end of the zoom lens according to Example 2;

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... 1st group, 12 ... 2nd group, 13 ... 3rd group, GC ... Cover glass, G1-G6 ... 1st lens-6th lens, Ri ... The curvature radius of the i-th lens surface from an object side, Di: a distance between the i-th lens surface and the (i + 1) -th lens surface from the object side, Simg: an imaging surface (imaging surface), Z1: an optical axis.

Claims (6)

In order from the object side, the zoom lens includes a first group having a negative refractive power, an aperture stop, a second group having a positive refractive power, and a third group having a positive refractive power. A group and the second group are configured to move on an optical axis;
The first group includes, in order from the object side, a first lens having a negative refractive power having an aspheric surface and a second lens having a positive refractive power,
The second group includes, in order from the object side, a third lens made of glass having a positive refractive power and an aspherical surface with a convex surface facing the object side in the vicinity of the paraxial axis, and a biconcave shape having a negative refractive power. Consists of a fourth lens and a fifth lens,
The third group is composed of only one biconvex sixth lens having positive refractive power,
At least one of the first lens and the sixth lens is a synthetic resin lens,
A zoom lens having a synthetic resin lens, characterized in that the following conditional expression is satisfied.
4.0 <Tw / fw <5.5 (1)
1.1 <f2g / fw <1.6 (2)
However,
fw: focal length of the entire system at the wide angle end Tw: conjugate distance (full length) at the wide angle end
f2g: focal length of the second group The fifth lens closest to the image side of the second group is a lens made of synthetic resin having an aspherical surface, and has a meniscus shape with a convex surface facing the object side in the vicinity of the paraxial axis;
The zoom lens having a synthetic resin lens according to claim 1, wherein the zoom lens is configured to satisfy the following conditional expression.
| Fw / fg5 | <15 (2-2)
However,
fg5: focal length of the fifth lens The zoom lens having a synthetic resin lens according to claim 1 or 2, further configured to satisfy the following conditional expression.
| F3 / ν3 + f4 / ν4 | / fw <0.06 (3)
However,
f3: focal length of the third lens f4: focal length of the fourth lens ν3: Abbe number of the third lens ν4: Abbe number of the fourth lens The zoom lens having the synthetic resin lens according to any one of claims 1 to 3, further configured to satisfy the following conditional expression.
0.4 <DG4 / fw <0.7 (4)
However,
DG4: Center thickness of the fourth lens The both sides of the first lens and the third lens are aspherical surfaces, and the first lens is a lens made of synthetic resin. A zoom lens with a synthetic resin lens. The zoom lens having a synthetic resin lens according to claim 5, wherein the sixth lens is a synthetic resin lens.

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