JP2012103416A - Zoom lens and imaging apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens capable of achieving a wide angle and a high variable power ratio of about 4, easily maintaining a good photographic image quality, and being advantageous in reducing the size and cost of a camera.SOLUTION: In a zoom lens including, in order from an object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, the first lens group includes a first lens having a negative refractive power and a second lens having a positive refractive power, and satisfies the following conditional expressions: (1) n≤1.70, (2) n≤1.70, and (3) |ν-ν|≥31, where nis a refractive index for the d line of the first lens having a negative refractive power in the first lens group, νis an Abbe number of the first lens having a negative refractive power in the first lens group, nis a refractive index for the d line of the second lens having a positive refractive power in the first lens group, and νis an Abbe number of the second lens having a positive refractive power in the first lens group.

Description

  The present invention relates to a zoom lens and an imaging apparatus using the same, and particularly suitable for a compact digital camera.

  In recent years, digital cameras that shoot a subject using a solid-state imaging device such as a CCD or CMOS instead of a silver salt film camera have become mainstream. Furthermore, it has come to have a number of categories in a wide range from high-functional types for business use to compact popular types. In the present invention, attention is focused on a category of a compact popular type.

  Users of such popular digital cameras have a desire to enjoy shooting in a wide range of scenes anytime and anywhere. For this reason, a digital camera of a type that is easy to carry in a small product, particularly a pocket of clothes or a bag, and that is easy to carry, is thin. Therefore, there is a demand for further downsizing of the taking lens system.

  In addition, a wide angle of view characteristic is required for the imaging region. Therefore, there is a need for an inexpensive zoom lens that has a high zoom ratio and a wide-angle range in which the diagonal angle of view exceeds 70 ° and can provide bright and high optical performance with a zoom ratio exceeding 3 times. It has been.

  As a prior art that constitutes a relatively wide-angle and bright zoom lens, there are a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a positive refractive power, and a fourth lens group from the object side. The following types of techniques are disclosed.

JP 2009-163222 A

  The optical system described in Patent Document 1 has a compact configuration as a whole while obtaining a high zoom ratio of about 4 times at a wide angle. Therefore, the refractive power of each lens constituting the zoom lens is increased, and in particular, the refractive power of the negative first lens in the first lens group having a negative refractive power is increased. Therefore, the optical system is configured using a glass material having a high refractive index.

  Since the glass material having a high refractive index has a large color dispersion (that is, a small Abbe number), aberration (chromatic aberration) occurs in the negative first lens. In order to suppress this aberration, the second lens requires a lens having a larger dispersion, and it has been difficult to sufficiently reduce chromatic aberration.

  In Patent Document 1, both the first lens and the second lens are made of a glass material having a high refractive index. For this reason, when an aspheric surface is used for the second lens, performance deterioration due to eccentricity error increases. Therefore, a spherical lens is used. When a spherical lens is used, the object distance is infinite and the image plane fluctuates greatly at close distance. Therefore, a lens group for aberration adjustment in the rear group, for example, the fourth lens group in Patent Document 1, is required. Become. Therefore, the entire zoom lens cannot be made compact.

  Further, when the negative first lens described above has a high refractive index, the decentration error related to the arrangement with the positive second lens arranged on the image plane side thereafter leads to a large decrease in the zoom lens performance. Therefore, in order to suppress the performance degradation due to eccentricity, it is necessary to widen the air gap between the negative first lens and the positive second lens to some extent. This hinders the entire zoom lens from being made compact.

  The present invention has been made in view of such problems, and an object of the present invention is to easily maintain a good image quality of a captured image while obtaining a high zoom ratio of about 4 times at a wide angle, and to reduce the size of the camera. It is another object of the present invention to provide a zoom lens advantageous for cost reduction and an imaging apparatus using the same.

In order to solve the above-described problems and achieve the object, the zoom lens of the present invention includes:
In order from the object side, a zoom lens having a first lens unit having a negative refractive power and a second lens group having a positive refractive power, the first lens group includes a first lens having a negative refractive power and a second lens having a positive refractive power. And satisfy the following conditional expressions (1), (2), and (3).
n _1n ≦ 1.70 (1)
n _1p ≦ 1.70 (2)
| Ν _1n −ν _1p | ≧ 31 (3)
However,
n _1n is the refractive index of the d-line of the first lens having negative refractive power in the first lens group,
ν _1n is the Abbe number of the first lens having negative refractive power in the first lens group,
n _1p is the refractive index of the d-line of the second lens having positive refractive power in the first lens group,
ν _1p is the Abbe number of the second lens having positive refractive power in the first lens group.

Hereinafter, the reason and effect | action which took such a structure are demonstrated.
In the present invention, a retrofocus type having a first lens group having a negative refractive power and a second lens group having a positive refractive power in order from the object side is employed. By configuring such an optical system, it is possible to configure a zoom optical system that ensures a certain degree of back focus while having a wide angle.

  Further, by satisfying conditional expressions (1) and (2), the refractive indexes of the negative first lens and the positive second lens can be suppressed. For this reason, the influence of the eccentricity generated between the first lens and the second lens is reduced. Therefore, manufacture becomes easy and it has a compact configuration.

Furthermore, since the influence of decentering is reduced, an optical design in which the negative first lens and the positive second lens are brought close to each other becomes possible. For this reason, the freedom degree of a compact optical system design increases.
Further, by satisfying conditional expression (3), chromatic dispersion generated in the first lens group can be corrected satisfactorily. For this reason, the aberration correction function in the rear group can be reduced or eliminated. As a result, a compact optical system can be configured.

In addition, it is preferable that the zoom lens of the present invention satisfies the following conditional expression (4).
Σd _1G /(ytan(2ω))≦0.3 (4)
However,
Σd _1G is the total length of the first lens group,
y is the maximum image height at the image plane in the zoom lens;
ω is a half field angle at the wide-angle end of the zoom lens.

  Conditional expression (4) defines the total length of the first lens group. This is normalized by the maximum image height of the image plane in the zoom lens, and further divided by the tangent of the zoom lens angle of view.

  If the upper limit of conditional expression (4) is exceeded, the total length of the first lens group becomes large or the angle of view at the wide-angle end of the zoom lens becomes small. The system cannot be configured.

The zoom lens according to the present invention preferably satisfies the following conditional expressions (5) and (6).
d _1nw / d _1nc ≧ 3.0 (5)
f _w /y≦1.4 (6)

However,
d 1 _nw is the lens thickness at the position where the outermost principal ray at the wide-angle end of the first lens having negative refractive power in the first lens group passes,
d 1 _nC is the lens thickness on the optical axis of the first lens having negative refractive power in the first lens group,
_fw is a focal length at the wide-angle end of the zoom lens.

Conditional expression (5) defines an appropriate range of the deviation ratio of the first lens having negative refractive power in the first lens group.
If the lower limit of conditional expression (5) is not reached, sufficient refractive power cannot be obtained with the negative first lens, and it becomes difficult to construct a zoom lens with a high zoom ratio.

  Conditional expression (6) is obtained by normalizing the focal length at the wide-angle end of the zoom lens by the maximum image height on the imaging surface of the zoom lens. If the upper limit of conditional expression (6) is exceeded, Since the focal length is increased and the total length of the optical system is increased, it is not preferable for a compact configuration.

In the zoom lens of the present invention, it is preferable that at least one of the first lens having the negative refractive power and the second lens having the positive refractive power in the first lens group is a resin lens.
Low cost by replacing at least one of the first lens with negative refracting power and the second lens with positive refracting power, which is conventionally made of a glass lens, with a resin lens in the first negative focus type lens group. Can be configured.

  In the zoom lens of the present invention, at least one lens surface of the first lens unit having the negative refracting power and the second lens unit having the positive refracting power is aspherical, and the aspherical surface is the center of the lens. It is preferable that the shape monotonously increases or decreases monotonously in the optical axis direction from the position where the outermost principal ray passes.

  Astigmatism can be corrected satisfactorily by employing an aspherical surface for at least one of the first lens having negative refractive power and the second lens having positive refractive power in the first lens group.

  The aspherical surface is formed such that the shape monotonously increases or decreases monotonously in the optical axis direction from the lens center to the position where the outermost principal ray passes, so that the first lens having negative refractive power and the positive refraction are obtained. The influence of the eccentricity generated by the second lens of force can be reduced. As a result, a compact design in which the distance between both lenses is made close is possible.

The zoom lens according to the present invention preferably satisfies the following conditional expressions (7) and (8).
d ₁₂ / | r _1nf | ≦ 0.2 (7)
d ₁₂ / | r _1pr | ≦ 0.2 (8)
However,
d ₁₂ is an air gap between the negative first lens and a positive second lens in the first lens group,
r _1nf is a radius of curvature of the negative first lens in the first lens group on the object side surface;
r _1pr is a radius of curvature at the image side surface of the positive second lens in the first lens group,
It is.

Conditional expression (7) is obtained by normalizing the air space between the negative first lens and the positive second lens in the first lens group by the radius of curvature at the object side surface of the negative first lens. .
Conditional expression (8) is obtained by normalizing the air gap between the negative first lens in the first lens group and the positive second lens by the radius of curvature at the image side surface of the positive second lens. .

Conditional expressions (7) and (8) mainly define the air gap between the negative first lens and the positive second lens.
Condition (7), the air gap d ₁₂ between the negative first lens and a positive second lens becomes large beyond the upper limit value of (8). This makes it difficult to make the optical system compact.

  Alternatively, when the upper limit value of conditional expressions (7) and (8) is exceeded, the radius of curvature on the object side surface of the negative first lens and the radius of curvature on the image side surface of the positive second lens become small, and negative first Astigmatism and lateral chromatic aberration that occur in one lens and the positive second lens increase, making it difficult to correct aberrations.

The zoom lens according to the present invention preferably satisfies the following conditional expressions (9) and (10).
d _t /y≦8.5 (9)
f _t / f _w ≧ 3.0 (10)
However,
_dt is the total length at the telephoto end of the zoom lens
f _t is the focal length, the zoom lens telephoto end.

  Conditional expression (9) is obtained by normalizing the entire length of the zoom lens at the telephoto end with the maximum image height of the image forming surface of the zoom lens. Conditional expression (9) mainly defines the total length of the zoom lens at the telephoto end.

If the upper limit of conditional expression (9) is exceeded, the total length of the zoom lens at the telephoto end becomes long, and a compact configuration cannot be taken.
Conditional expression (10) defines the zoom ratio. Conditional expression (9) is satisfied, and conditions for ensuring a high zoom ratio while taking a compact configuration are defined.

The zoom lens according to the present invention preferably satisfies the following conditional expressions (11) and (10).
d _w /y≦8.1 (11)
f _t / f _w ≧ 3.0 (10)
However,
_dw is the total length at the wide-angle end of the zoom lens.

  Conditional expression (11) is obtained by normalizing the entire length of the zoom lens at the wide-angle end with the maximum image height of the image forming surface of the zoom lens. Conditional expression (11) mainly defines the total length of the zoom lens at the wide angle end.

  If the upper limit of conditional expression (11) is exceeded, the entire length of the zoom lens at the wide-angle end becomes long, and a compact configuration cannot be taken.

In the zoom lens of the present invention, it is preferable that all the lenses constituting the zoom lens are composed of lenses having a refractive index of 1.7 or less.
In the zoom lens of the present invention, when a lens having a refractive index larger than 1.7 is used, the glass type of the lens is limited. This increases the price of the lens, making it difficult to provide an inexpensive zoom lens.

  In addition, lens processing becomes difficult and aberration correction becomes difficult. Furthermore, anomalous dispersion or the like occurs, making it difficult to correct aberrations.

Moreover, it is preferable that the zoom lens according to the present invention satisfies the following conditional expression (12).
Σd _2G /(ytan(2ω))≦0.35 (12)
However,
Σd _2G is the total length of the second lens group, and y is the maximum image height on the image plane of the zoom lens.

  Conditional expression (12) defines the total length of the second lens group. Conditional expression (12) is normalized by the maximum image height of the image forming plane in the zoom lens and further divided by the tangent of the zoom lens field angle.

  When the upper limit value of conditional expression (12) is exceeded, the total length of the second lens group becomes large, or the angle of view at the wide-angle end of the zoom lens becomes small. This makes it impossible to construct a compact optical system with a high angle of view, which is the object of the present invention.

Moreover, it is preferable that the zoom lens of the present invention satisfies the following conditional expression.
| F _air | / | f _1G | ≧ 15 (13)
However,
f _air is a focal length of an air lens formed between the first lens and the second lens,
f _1G is a focal length of the first lens group.

  Conditional expression (13) is obtained by normalizing the focal length of the air lens with the focal length of the first lens unit. If the lower limit value of conditional expression (13) is not reached, the focal length of the air lens becomes smaller (shorter), so that the radius of curvature of the lens surface formed by the air lens becomes smaller. Thereby, the deterioration of the performance due to the eccentricity of the negative first lens and the positive second lens becomes large. In the air lens, the chromatic aberration generated in the first lens group is corrected. However, the correction amount is kept small and the whole is made compact.

Moreover, it is preferable that the zoom lens according to the present invention satisfies the following conditional expression (14).
d _t /(ytan(2ω))≦1.7 (14)
Conditional expression (14) is obtained by normalizing the total length of the zoom lens at the telephoto end by the maximum image height of the imaging surface of the zoom lens and further dividing by the tangent of the zoom lens field angle.
If the upper limit of conditional expression (14) is exceeded, the entire length of the zoom lens becomes longer with respect to the angle of view, making it difficult to adopt a compact configuration.

Moreover, it is preferable that the zoom lens of the present invention satisfies the following conditional expression.
d _w / (ytan (2ω)) ≦ 1.7 (15)
Conditional expression (15) is obtained by normalizing the total length of the zoom lens at the wide-angle end by the maximum image height of the image formation surface of the zoom lens and dividing the tangent of the zoom lens angle of view.
If the upper limit of conditional expression (15) is exceeded, the entire length of the zoom lens becomes longer with respect to the angle of view, making it difficult to adopt a compact configuration.

Further, the present invention is a zoom lens having, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, and the first lens group includes: It is preferable that the first lens having a negative refractive power and the second lens having a positive refractive power are satisfied and the following conditional expression is satisfied.
n _1n ≦ 1.70 (1)
n _1p ≦ 1.70 (2)
| Ν _1n −ν _1p | ≧ 31 (3)
However,
n _1n is the refractive index of the first lens of d-line having negative refractive power in the first lens group,
ν _1n is the Abbe number of the first lens having negative refractive power in the first lens group,
n _1p is the refractive index of the second lens of the d-line with positive refractive power in the first lens group,
ν _1p is the Abbe number of the second lens having positive refractive power in the first lens group,
It is.

  In the present invention, a retrofocus type configuration having, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third group having a positive refractive power. By configuring such an optical system, it is possible to configure a zoom optical system that ensures a certain degree of back focus while having a wide angle.

  Thereby, when the third lens group is added, the refractive power that the first lens group bears is smaller than in the configuration of only the second group. For this reason, it is possible to reduce deterioration of field curvature and astigmatism due to decentration occurring in the first lens group.

Moreover, it is preferable that the zoom lens of the present invention satisfies the following conditional expression.
d _w3i tan (2ω) / y ≧ 5 (16)
However,
_dw3i is an air space between the image side surface and the image forming surface of the third lens group at the wide angle end.

  Conditional expression (16) defines the air space between the image side surface and the image forming surface of the second lens group. Conditional expression (16) is obtained by normalizing with the maximum image height of the image forming surface in the zoom lens and further multiplying the tangent of the zoom lens angle of view.

If the lower limit value of conditional expression (16) is not reached, the air space between the image side surface and the image forming surface of the third lens group cannot be secured, and it becomes difficult to insert an optical component such as a filter.
In addition, as the air distance between the third lens group and the imaging surface approaches, the angle at which the ambient light transmitted through the lens is obliquely incident on the imaging surface is increased, which impedes detection of the amount of light.

The imaging device of the present invention is
The zoom lens described above;
The image pickup device is provided on an image side of the zoom lens and converts an optical image formed by the zoom lens into an electric signal.
As a result, it is possible to obtain an imaging device having a wide angle, a small size, a high zoom ratio, low cost and good image quality.

Moreover, it becomes a more preferable structure by changing a conditional expression as follows.
n _1n ≦ 1.55 (1) ′
n _1n ≦ 1.54 (1) ″
n _1p ≦ 1.65 (2) ′
n _1p ≦ 1.64 (2) ″
| Ν _1n −ν _1p | ≧ 31.79 (3) ′
Σd _1G /(ytan(2ω))≦0.13 (4) ′
Σd _1G /(ytan(2ω))≦0.08 (4) ″
d _1nw / d _1nc ≧ 3.2 (5) ′
d _1nw / d _1nc ≧ 3.3 (5) ″
f _w /y≦1.35 (6) ′
f _w /y≦1.28 (6) ″
d ₁₂ / | r _1nf | ≦ 0.12 (7) ′
d ₁₂ / | r _1nf | ≦ 0.09 (7) ″
d ₁₂ / | r _1pr | ≦ 0.12 (8) ′
d ₁₂ / | r _1pr | ≦ 0.11 (8) ″
d _t /y≦8.45 (9) ′
d _t /y≦8.44 (9) ″
f _t / f _w ≧ 3.8 (10) ′
d _w /y≦8.01 (11) ′
d _w /y≦7.19 (11) ″
Σd _2G /(ytan(2ω))≦0.32 (12) ′
Σd _2G /(ytan(2ω))≦0.12 (12) ″
Σd _2G /(ytan(2ω))≦0.07 (12) ′ ″
| F _air | / | f _1G | ≧ 17 (13) ′
| F _air | / | f _1G | ≧ 40 (13) ″
d _t /(ytan(2ω))≦1.13 (14) ′
d _t /(ytan(2ω))≦0.65 (14) ″
d _w /(ytan(2ω))≦0.95 (15) ′
d _w /(ytan(2ω))≦0.56 (15) ″
d _w3i tan (2ω) / y ≧ 10 (16) ′
d _w3i tan (2ω) / y ≧ 17 (16) ″

Only the upper limit value or only the lower limit value of each conditional expression may be used as the new upper limit value and lower limit value.

  As is apparent from the above description, according to the present invention, it is easy to maintain a good image quality of a captured image while obtaining a high zoom ratio of about 4 times at a wide angle, which is advantageous for downsizing and cost reduction of the camera. Zoom lenses and devices can be provided.

FIG. 2 is a lens cross-sectional view at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on an object point at infinity according to the first exemplary embodiment of the zoom lens of the present invention. It is the same figure as FIG. 1 of Example 2 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 3 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 4 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 5 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 6 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 7 of the zoom lens of this invention. It is a figure similar to FIG. 1 of Example 8 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 9 of the zoom lens of this invention. It is a figure similar to FIG. 1 of Example 10 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 11 of the zoom lens of this invention. FIG. 6 is an aberration diagram for Example 1 upon focusing on an object point at infinity. FIG. 6 is an aberration diagram for Example 2 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 3 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 4 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 5 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 6 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 7 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 8 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 9 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 10 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 11 upon focusing on an object point at infinity. It is a figure explaining correction | amendment of a distortion aberration. It is a front perspective view which shows the external appearance of the digital camera incorporating the zoom lens by this invention. It is a rear view of the digital camera. It is sectional drawing of the said digital camera. It is a block diagram of the internal circuit of the main part of the digital camera.

  Embodiments of a zoom lens and an imaging apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Examples 1 to 11 of the zoom lens according to the present invention will be described below. FIGS. 1 to 11 show lens cross-sectional views of the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on an object point at infinity in Examples 1 to 11, respectively. 1 to 11, the first lens group is G1, the second lens group is G2, the brightness (aperture) stop is S, the third lens group is G3, the filter is F, and an electronic image sensor (CCD, C-MOS). The parallel plate of the cover glass of the sensor is indicated by C and the image plane is indicated by I. In addition, you may give the multilayer film for a wavelength range restriction | limiting to the surface of the cover glass C. FIG. In addition, the cover glass C may have a low-pass filter function in which a wavelength range limiting coat that limits infrared light is applied.
The parallel plate F may not have the function of a low bass filter.

The numerical data is data in a state where the subject is focused on an object at infinity. The unit of length of each numerical value is mm, and the unit of angle is ° (degree). Focusing from a long distance object to a short distance object is performed by moving the first lens group, the third lens group, or all the lens groups in the optical axis direction.
Further, zoom data is values at the wide-angle end (W), the intermediate focal length state (S), and the telephoto end (T).

  As shown in FIG. 1, the zoom lens of Example 1 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power, A third lens group G3 having a positive refractive power is disposed.

During zooming from the wide-angle end to the telephoto end
The first lens group G1 moves to the image side, then reverses, and moves to the object side.
The second lens group G2 moves to the object side.
The third lens group G3 moves to the image side.

In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface directed toward the object side.
The second lens group G2 includes a biconvex positive lens and a cemented lens of a biconvex positive lens and a biconcave negative lens.
The third lens group G3 is composed of a positive meniscus lens having a convex surface directed toward the image side.

  The aspherical surfaces include both surfaces of a biconcave negative lens of the first lens group G1, both surfaces of a positive meniscus lens having a convex surface facing the object side, both surfaces of a biconvex positive lens of the second lens group G2, and a third lens group. It is used for seven surfaces, that is, the image side surface of a positive meniscus lens having a convex surface facing the image side of G3.

  As shown in FIG. 1, the zoom lens of Example 2 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power, A third lens group G3 having a positive refractive power is disposed.

During zooming from the wide-angle end to the telephoto end,
The first lens group G1 moves to the image side, then reverses, and moves to the object side.
The second lens group G2 moves to the object side.
The third lens group G3 moves to the image side.

In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface directed toward the object side.
The second lens group G2 includes a biconvex positive lens and a negative meniscus lens having a convex surface directed toward the object side.
The third lens group G3 is composed of a positive meniscus lens having a convex surface directed toward the image side.

  The aspherical surfaces are both surfaces of a biconcave negative lens in the first lens group G1, both surfaces of a positive meniscus lens having a convex surface facing the object side, both surfaces of a biconvex positive lens in the second lens group G2, and a convex surface on the object side. Are used for eight surfaces, that is, the image side surface of the negative meniscus lens facing the image side and the image side surface of the positive meniscus lens having the convex surface facing the image side of the third lens group G3.

  As shown in FIG. 3, the zoom lens of Example 3 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power, A third lens group G3 having a positive refractive power is disposed.

During zooming from the wide-angle end to the telephoto end,
The first lens group G1 moves to the image side, then reverses, and moves to the object side.
The second lens group G2 moves to the object side.
The third lens group G3 moves to the image side.

In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface directed toward the object side.
The second lens group G2 includes a biconvex positive lens and a negative meniscus lens having a convex surface directed toward the object side.
The third lens group G3 is composed of a positive meniscus lens having a convex surface directed toward the image side.

  The aspherical surfaces are both surfaces of a biconcave negative lens in the first lens group G1, both surfaces of a positive meniscus lens having a convex surface facing the object side, both surfaces of a biconvex positive lens in the second lens group G2, and a convex surface on the object side. Are used for eight surfaces, that is, the image side surface of the negative meniscus lens facing the image side and the image side surface of the positive meniscus lens having the convex surface facing the image side of the third lens group G3.

  As shown in FIG. 4, the zoom lens of Example 4 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power, A third lens group G3 having a positive refractive power is disposed.

During zooming from the wide-angle end to the telephoto end,
The first lens group G1 moves to the image side, then reverses, and moves to the object side.
The second lens group G2 moves to the object side.
The third lens group G3 moves to the image side.

In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface directed toward the object side.
The second lens group G2 includes a biconvex positive lens and a cemented lens of a biconvex positive lens and a biconcave negative lens.
The third lens group G3 is composed of a positive meniscus lens having a convex surface directed toward the image side.

  The aspherical surfaces include both surfaces of a biconcave negative lens of the first lens group G1, both surfaces of a positive meniscus lens having a convex surface facing the object side, both surfaces of a biconvex positive lens of the second lens group G2, and a third lens group. It is used for seven surfaces, that is, the image side surface of a positive meniscus lens having a convex surface facing the image side of G3.

  As shown in FIG. 5, the zoom lens of Example 5 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, a second lens group G2 having a positive refractive power, A third lens group G3 having a positive refractive power is disposed.

During zooming from the wide-angle end to the telephoto end,
The first lens group G1 moves to the image side, then reverses, and moves to the object side.
The second lens group G2 moves to the object side.
The third lens group G3 moves to the image side.

In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface directed toward the object side.
The second lens group G2 includes a biconvex positive lens and a cemented lens of a biconvex positive lens and a biconcave negative lens.
The third lens group G3 is composed of a positive meniscus lens having a convex surface directed toward the image side.

  The aspherical surfaces include both surfaces of a biconcave negative lens of the first lens group G1, both surfaces of a positive meniscus lens having a convex surface facing the object side, both surfaces of a biconvex positive lens of the second lens group G2, and a third lens group. It is used for seven surfaces, that is, the image side surface of a positive meniscus lens having a convex surface facing the image side of G3.

  As shown in FIG. 6, the zoom lens of Example 6 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, a second lens group G2 having a positive refractive power, A third lens group G3 having a positive refractive power is disposed.

During zooming from the wide-angle end to the telephoto end,
The first lens group G1 moves to the image side, then reverses, and moves to the object side.
The second lens group G2 moves to the object side.
The third lens group G3 moves to the image side.

In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface directed toward the object side.
The second lens group G2 includes a biconvex positive lens and a cemented lens of a biconvex positive lens and a biconcave negative lens.
The third lens group G3 is composed of a positive meniscus lens having a convex surface directed toward the image side.

  The aspherical surfaces include both surfaces of a biconcave negative lens of the first lens group G1, both surfaces of a positive meniscus lens having a convex surface facing the object side, both surfaces of a biconvex positive lens of the second lens group G2, and a third lens group. It is used for seven surfaces, that is, the image side surface of a positive meniscus lens having a convex surface facing the image side of G3.

  As shown in FIG. 7, the zoom lens of Example 7 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, a second lens group G2 having a positive refractive power, A third lens group G3 having a positive refractive power is disposed.

During zooming from the wide-angle end to the telephoto end,
The first lens group G1 moves to the image side, then reverses, and moves to the object side.
The second lens group G2 moves to the object side.
The third lens group G3 moves to the image side.

In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface directed toward the object side.
The second lens group G2 includes a biconvex positive lens and a cemented lens of a biconvex positive lens and a biconcave negative lens.
The third lens group G3 is composed of a positive meniscus lens having a convex surface directed toward the image side.

  The aspherical surfaces include both surfaces of a biconcave negative lens of the first lens group G1, both surfaces of a positive meniscus lens having a convex surface facing the object side, both surfaces of a biconvex positive lens of the second lens group G2, and a third lens group. It is used for seven surfaces, that is, the image side surface of a positive meniscus lens having a convex surface facing the image side of G3.

  As shown in FIG. 8, the zoom lens of Example 8 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power, A third lens group G3 having a positive refractive power is disposed.

During zooming from the wide-angle end to the telephoto end,
The first lens group G1 moves to the image side, then reverses, and moves to the object side.
The second lens group G2 moves to the object side.
The third lens group G3 moves to the image side.

In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface directed toward the object side.
The second lens group G2 includes a biconvex positive lens and a cemented lens of a biconvex positive lens and a biconcave negative lens.
The third lens group G3 is composed of a positive meniscus lens having a convex surface directed toward the image side.

  The aspherical surfaces include both surfaces of a biconcave negative lens of the first lens group G1, both surfaces of a positive meniscus lens having a convex surface facing the object side, both surfaces of a biconvex positive lens of the second lens group G2, and a third lens group. It is used for seven surfaces, that is, the image side surface of a positive meniscus lens having a convex surface facing the image side of G3.

  As shown in FIG. 9, the zoom lens of Example 9 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, a second lens group G2 having a positive refractive power, A third lens group G3 having a positive refractive power is disposed.

During zooming from the wide-angle end to the telephoto end,
The first lens group G1 moves to the image side, then reverses, and moves to the object side.
The second lens group G2 moves to the object side.
The third lens group G3 moves to the image side.

In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface directed toward the object side.
The second lens group G2 includes a biconvex positive lens and a cemented lens of a biconvex positive lens and a biconcave negative lens.
The third lens group G3 is composed of a positive meniscus lens having a convex surface directed toward the image side.

  The aspherical surfaces include both surfaces of a biconcave negative lens of the first lens group G1, both surfaces of a positive meniscus lens having a convex surface facing the object side, both surfaces of a biconvex positive lens of the second lens group G2, and a third lens group. It is used for seven surfaces, that is, the image side surface of a positive meniscus lens having a convex surface facing the image side of G3.

  As shown in FIG. 10, the zoom lens of Example 10 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power. It is arranged.

During zooming from the wide-angle end to the telephoto end,
The first lens group G1 moves to the image side, then reverses, and moves to the object side.
The second lens group G2 moves to the object side.

In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface directed toward the object side.
The second lens group G2 includes a biconvex positive lens and a cemented lens of a negative meniscus lens having a convex surface facing the image side and a biconcave negative lens.

  The aspherical surfaces are both surfaces of a biconcave negative lens in the first lens group G1, both surfaces of a positive meniscus lens having a convex surface facing the object side, both surfaces of a biconvex positive lens in the second lens group G2, and a convex surface on the image side. Are used for eight surfaces, that is, the object side surface of the negative meniscus lens and the image side surface of the biconcave negative lens.

  As shown in FIG. 11, the zoom lens of Example 11 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power. It is arranged.

During zooming from the wide-angle end to the telephoto end,
The first lens group G1 moves to the image side, then reverses, and moves to the object side.
The second lens group G2 moves to the object side.

In order from the object side, the first lens group G1 includes a biconcave negative lens and a positive meniscus lens having a convex surface directed toward the object side.
The second lens group G2 includes a biconvex positive lens and a cemented lens of a negative meniscus lens having a convex surface facing the image side and a biconcave negative lens.

  The aspherical surfaces are both surfaces of a biconcave negative lens in the first lens group G1, both surfaces of a positive meniscus lens having a convex surface facing the object side, both surfaces of a biconvex positive lens in the second lens group G2, and a convex surface on the image side. Are used for eight surfaces, that is, the object side surface of the negative meniscus lens and the image side surface of the biconcave negative lens.

Below, the numerical data of each said Example are shown. Symbols are the above, fb is the back focus, f1, f2... Are the focal lengths of the lens groups, _FNO is the F number, ω is the half angle of view, r is the radius of curvature of each lens surface, and d is the distance between the lens surfaces. Nd is the refractive index of the d-line (λ = 587.6 nm) of each lens, and νd is the Abbe number of each lens. The total lens length described later is obtained by adding back focus to the distance from the lens front surface to the lens final surface. fb (back focus) represents the distance from the last lens surface to the paraxial image plane in terms of air.

  The aspherical shape is represented by the following expression, where z is an optical axis with the light traveling direction being positive, and y is a direction orthogonal to the optical axis.

Z = (Y ² / r) / [1+ {1− (1 + K) · (Y / r) ² } ^1/2 ]
+ A4 × Y ⁴ + A6 × Y ⁶ + A8 × Y ⁸ + A10 × Y ¹⁰
Here, r is a paraxial radius of curvature, K is a conical coefficient, and A4, A6, A8, A10, and A12 are fourth, sixth, eighth, tenth, and twelfth aspheric coefficients, respectively. In the aspheric coefficient, “E−n” (n is an integer) indicates “10 ⁻ⁿ ”.

Numerical example 1
Unit: mm

Surface data surface number rd nd υd
Object ∞ ∞
1 * -16.345 0.93 1.53071 55.69
2 * 5.151 1.33
3 * 7.164 1.44 1.63493 23.90
4 * 12.958 Variable
5 (Aperture) ∞ 0.74
6 * 4.125 1.35 1.58313 59.46
7 * -12.794 0.10
8 7.081 1.21 1.58313 59.38
9 -14.510 0.40 1.64769 33.79
10 2.942 Variable
11 -37.664 1.53 1.53071 55.69
12 * -7.566 variable
13 ∞ 0.30 1.51633 64.14
14 ∞ 0.50
15 ∞ 0.50 1.51633 64.14
16 ∞ 0.40
Image plane (imaging plane) ∞

Aspheric data first surface
k = 0.000
A4 = 1.36010e-03, A6 = -4.61920e-05, A8 = 7.50200e-07, A10 = -4.88790e-09
Second side
k = -0.026
A4 = 3.82340e-04, A6 = 5.79610e-05, A8 = -3.99820e-06
Third side
k = 0.000
A4 = -1.19550e-03
4th page
k = 0.000
A4 = -1.15110e-03, A6 = -2.54540e-05, A8 = 1.45560e-06, A10 = -2.09940e-08
6th page
k = 0.000
A4 = -1.57890e-03, A6 = -5.29490e-05, A8 = 5.58160e-08, A10 = -1.28580e-07,
A12 = 5.30060e-08
7th page
k = 0.000
A4 = 9.35380e-04, A6 = -4.66310e-05, A8 = 6.28670e-06
12th page
k = 0.000
A4 = 7.07160e-04, A6 = -1.32700e-05, A8 = 3.95410e-07, A10 = -3.96690e-09

Zoom data
Wide angle Medium Telephoto focal length 4.90 9.34 18.76
FNO. 2.95 4.17 6.64
Angle of view 2ω 85.55 44.71 22.82
fb (in air) 5.23 4.70 4.72
Total length (in air) 27.58 26.23 32.40

d4 10.85 4.56 0.75
d10 2.47 7.94 17.90
d12 3.78 3.28 3.26

Group focal length
f1 = -10.96 f2 = 8.65 f3 = 17.53

Numerical example 2
Unit: mm

Surface data surface number rd nd υd
Object ∞ ∞
1 * -17.690 0.97 1.53110 55.91
2 * 4.548 1.53
3 * 7.200 1.40 1.63493 23.90
4 * 14.000 variable
5 (Aperture) ∞ 0.70
6 * 3.485 1.58 1.52542 55.78
7 * -8.823 0.10
8 13.204 1.30 1.63493 23.90
9 * 3.229 Variable
10 -30.863 1.60 1.53110 55.91
11 * -7.430 variable
12 ∞ 0.30 1.51633 64.14
13 ∞ 0.30
14 ∞ 0.50 1.51633 64.14
15 ∞ 0.37
Image plane (imaging plane) ∞

Aspheric data first surface
k = 0.000
A4 = 8.43297e-04, A6 = -1.63292e-05, A8 = 1.04209e-07
Second side
k = -0.884
A4 = 5.69444e-04, A6 = 7.10052e-05, A8 = -7.41429e-07
Third side
k = 0.000
A4 = -1.24294e-03
4th page
k = 0.000
A4 = -1.11565e-03, A6 = -2.47496e-05, A8 = 9.40826e-07, A10 = -3.84417e-08
6th page
k = -0.127
A4 = -1.22185e-03, A6 = -9.42415e-05, A8 = 5.18279e-06
7th page
k = 0.000
A4 = 3.56516e-03, A6 = -3.76966e-04, A8 = 3.79448e-05
9th page
k = 0.000
A4 = -9.21985e-05, A6 = 7.33874e-04
11th page
k = 0.000
A4 = 8.45238e-04, A6 = -1.29767e-05, A8 = 1.82787e-07, A10 = 1.96786e-09

Zoom data
Wide angle Medium telephoto focal length 4.57 8.73 17.59
FNO. 2.95 4.19 6.62
Angle of view 2ω 89.27 47.59 24.18
fb (in air) 5.29 4.40 4.25
Total length (in air) 27.80 26.48 32.03

d4 10.82 4.65 0.75
d9 2.50 8.24 17.85
d11 4.09 3.20 3.05

Group focal length
f1 = -10.30 f2 = 8.59 f3 = 18.00

Numerical Example 3
Unit: mm

Surface data surface number rd nd υd
Object ∞ ∞
1 * -18.212 0.96 1.53110 55.91
2 * 5.012 1.28
3 * 7.195 1.36 1.63493 23.90
4 * 14.000 variable
5 (Aperture) ∞ 0.70
6 * 3.846 1.47 1.58313 59.38
7 * -13.220 0.10
8 9.170 1.32 1.63493 23.90
9 * 2.992 variable
10 -40.000 1.60 1.53110 55.91
11 * -7.654 variable
12 ∞ 0.30 1.51633 64.14
13 ∞ 0.30
14 ∞ 0.50 1.51633 64.14
15 ∞ 0.37
Image plane (imaging plane) ∞

Aspheric data first surface
k = 0.000
A4 = 7.02354e-04, A6 = -1.54766e-05, A8 = 1.24503e-07
Second side
k = -0.687
A4 = 3.90910e-04, A6 = 3.69947e-05, A8 = -1.06912e-06
Third side
k = 0.000
A4 = -1.17271e-03
4th page
k = 0.000
A4 = -1.15180e-03, A6 = 2.07735e-06, A8 = -2.39987e-07, A10 = 5.32718e-09
6th page
k = -0.038
A4 = -1.63619e-03, A6 = -5.38827e-05, A8 = -7.46946e-06
7th page
k = 0.000
A4 = 1.33473e-03, A6 = -1.20950e-04, A8 = 5.48702e-06
9th page
k = 0.000
A4 = 1.84642e-04, A6 = 2.15165e-04
11th page
k = 0.000
A4 = 6.95014e-04, A6 = -1.58986e-05, A8 = 4.76348e-07, A10 = -5.00332e-09

Zoom data
Wide angle Medium Telephoto focal length 4.88 9.31 18.74
FNO. 2.95 4.22 6.66
Angle of view 2ω 85.58 45.24 23.10
fb (in air) 5.47 4.43 4.23
Total length (in air) 27.96 26.60 31.94

d4 11.28 4.91 0.76
d9 2.41 8.46 18.16
d11 4.27 3.24 3.03

Group focal length
f1 = -11.49 f2 = 8.94 f3 = 17.52

Numerical Example 4
Unit: mm

Surface data surface number rd nd υd
Object ∞ ∞
1 * -17.515 0.70 1.53071 55.69
2 * 4.849 1.00
3 * 6.696 1.80 1.63493 23.90
4 * 14.000 variable
5 (Aperture) ∞ 0.74
6 * 4.371 1.38 1.58313 59.46
7 * -11.511 0.10
8 7.711 1.25 1.58313 59.38
9 -11.568 0.40 1.64769 33.79
10 3.150 Variable
11 -63.056 1.63 1.53071 55.69
12 * -8.183 variable
13 ∞ 0.30 1.51633 64.14
14 ∞ 0.50
15 ∞ 0.50 1.51633 64.14
16 ∞ 0.37
Image plane (imaging plane) ∞

Aspheric data first surface
k = 0.000
A4 = 1.39425e-03, A6 = -6.09420e-05, A8 = 1.34243e-06, A10 = -1.29957e-08
Second side
k = -0.374
A4 = 7.11209e-04, A6 = 3.55068e-05, A8 = -2.54955e-06
Third side
k = 0.000
A4 = -1.12190e-03
4th page
k = 0.000
A4 = -9.95014e-04, A6 = -2.76050e-05, A8 = 1.47640e-06, A10 = -2.09230e-08
6th page
k = 0.370
A4 = -2.39300e-03, A6 = 5.30081e-06, A8 = -2.82042e-05
7th page
k = 0.000
A4 = 3.79008e-04, A6 = 5.93252e-05, A8 = -2.51578e-05
12th page
k = 0.000
A4 = 6.34942e-04, A6 = -1.39741e-05, A8 = 4.07374e-07, A10 = -4.92068e-09

Zoom data
Wide angle Medium Telephoto focal length 5.18 9.88 19.88
FNO. 2.96 4.19 6.70
Angle of view 2ω 82.42 42.42 21.58
fb (in air) 5.37 4.86 4.65
Total length (in air) 27.36 26.13 32.53

d4 10.62 4.27 0.50
d10 2.37 7.99 18.38
d12 3.97 3.47 3.25

Group focal length
f1 = -11.67 f2 = 8.82 f3 = 17.54

Numerical Example 5
Unit: mm

Surface data surface number rd nd υd
Object ∞ ∞
1 * -23.721 0.20 1.53071 55.69
2 * 4.902 1.45
3 * 7.725 1.60 1.63493 23.90
4 * 14.000 variable
5 (Aperture) ∞ 0.74
6 * 4.387 1.43 1.58313 59.46
7 * -11.644 0.10
8 7.644 1.21 1.58313 59.38
9 -15.930 0.40 1.64769 33.79
10 3.154 Variable
11 -96.588 1.78 1.53071 55.69
12 * -8.442 variable
13 ∞ 0.30 1.51633 64.14
14 ∞ 0.50
15 ∞ 0.50 1.51633 64.14
16 ∞ 0.37
Image plane (imaging plane) ∞

Aspheric data first surface
k = 0.000
A4 = 1.28899e-03, A6 = -6.37925e-05, A8 = 1.51529e-06, A10 = -1.52648e-08
Second side
k = -0.527
A4 = 9.71350e-04, A6 = 3.37846e-05, A8 = -2.05316e-06
Third side
k = 0.000
A4 = -9.12718e-04
4th page
k = 0.000
A4 = -9.95014e-04, A6 = -2.76050e-05, A8 = 1.47640e-06, A10 = -2.09230e-08
6th page
k = 0.370
A4 = -2.31889e-03, A6 = -8.42149e-06, A8 = -2.36917e-05
7th page
k = 0.000
A4 = 4.36788e-04, A6 = 4.73162e-05, A8 = -2.08166e-05
12th page
k = 0.000
A4 = 6.34942e-04, A6 = -1.39741e-05, A8 = 4.07374e-07, A10 = -4.92068e-09

Zoom data
Wide angle Medium Telephoto focal length 5.01 9.57 19.25
FNO. 2.95 4.19 6.69
Angle of view 2ω 84.07 43.72 22.19
fb (in air) 5.31 4.74 4.65
Total length (in air) 27.22 26.08 32.53

d4 10.62 4.32 0.50
d10 2.37 8.10 18.46
d12 3.92 3.34 3.25

Group focal length
f1 = -11.30 f2 = 8.85 f3 = 17.31

Numerical Example 6
Unit: mm

Surface data surface number rd nd υd
Object ∞ ∞
1 * -26.034 0.10 1.53071 55.69
2 * 4.860 1.50
3 * 7.865 1.60 1.63493 23.90
4 * 14.000 variable
5 (Aperture) ∞ 0.74
6 * 4.429 1.48 1.58313 59.46
7 * -11.550 0.10
8 7.628 1.20 1.58313 59.38
9 -17.498 0.40 1.64769 33.79
10 3.174 Variable
11 -94.557 1.79 1.53071 55.69
12 * -8.432 variable
13 ∞ 0.30 1.51633 64.14
14 ∞ 0.50
15 ∞ 0.50 1.51633 64.14
16 ∞ 0.37
Image plane (imaging plane) ∞

Aspheric data first surface
k = 0.000
A4 = 1.30625e-03, A6 = -6.92556e-05, A8 = 1.71259e-06, A10 = -1.77917e-08
Second side
k = -0.572
A4 = 1.11928e-03, A6 = 3.06525e-05, A8 = -2.03600e-06
Third side
k = 0.000
A4 = -8.49690e-04
4th page
k = 0.000
A4 = -9.95014e-04, A6 = -2.76050e-05, A8 = 1.47640e-06, A10 = -2.09230e-08
6th page
k = 0.370
A4 = -2.29302e-03, A6 = -1.20091e-05, A8 = -2.23007e-05
7th page
k = 0.000
A4 = 4.16200e-04, A6 = 4.10538e-05, A8 = -1.97552e-05
12th page
k = 0.000
A4 = 6.34942e-04, A6 = -1.39741e-05, A8 = 4.07374e-07, A10 = -4.92068e-09

Zoom data
Wide angle Medium Telephoto focal length 4.99 9.52 19.16
FNO. 2.95 4.19 6.68
Angle of view 2ω 84.35 43.92 22.30
fb (in air) 5.31 4.75 4.65
Total length (in air) 27.22 26.08 32.53

d4 10.63 4.33 0.51
d10 2.37 8.09 18.46
d12 3.91 3.35 3.25

Group focal length
f1 = -11.25 f2 = 8.85 f3 = 17.32

Numerical Example 7
Unit: mm

Surface data surface number rd nd υd
Object ∞ ∞
1 * -20.430 0.91 1.49700 81.54
2 * 5.580 1.60
3 * 9.604 1.32 1.63493 23.90
4 * 14.000 variable
5 (Aperture) ∞ 0.74
6 * 4.213 1.34 1.58313 59.46
7 * -12.201 0.10
8 7.099 1.21 1.58313 59.38
9 -16.655 0.40 1.64769 33.79
10 2.973 Variable
11 -54.836 1.54 1.53071 55.69
12 * -8.059 variable
13 ∞ 0.30 1.51633 64.14
14 ∞ 0.50
15 ∞ 0.50 1.51633 64.14
16 ∞ 0.37
Image plane (imaging plane) ∞

Aspheric data first surface
k = 0.000
A4 = 1.88172e-03, A6 = -8.26946e-05, A8 = 1.66830e-06, A10 = -1.39650e-08
Second side
k = 0.020
A4 = 2.22905e-03, A6 = 4.46761e-05, A8 = -4.28166e-06
Third side
k = 0.000
A4 = -3.40638e-04
4th page
k = 0.000
A4 = -9.95014e-04, A6 = -2.76050e-05, A8 = 1.47640e-06, A10 = -2.09230e-08
6th page
k = 0.370
A4 = -2.53287e-03, A6 = 3.51677e-05, A8 = -3.96905e-05
7th page
k = 0.000
A4 = 4.12045e-04, A6 = 1.00950e-04, A8 = -3.59184e-05
12th page
k = 0.000
A4 = 6.34942e-04, A6 = -1.39741e-05, A8 = 4.07374e-07, A10 = -4.92068e-09

Zoom data
Wide angle Medium telephoto focal length 4.86 9.27 18.61
FNO. 2.96 4.16 6.65
Angle of view 2ω 86.06 45.11 23.06
fb (in air) 5.26 4.90 4.72
Total length (in air) 27.62 26.15 32.40

d4 10.84 4.43 0.72
d10 2.37 7.67 17.80
d12 3.84 3.47 3.25

Group focal length
f1 = -10.97 f2 = 8.66 f3 = 17.60

Numerical Example 8
Unit: mm

Surface data surface number rd nd υd
Object ∞ ∞
1 * -13.629 0.91 1.43875 94.93
2 * 6.447 1.60
3 * 11.163 1.16 1.63493 23.90
4 * 14.000 variable
5 (Aperture) ∞ 0.74
6 * 4.261 1.34 1.58313 59.46
7 * -13.881 0.10
8 6.367 1.20 1.58313 59.38
9 -43.376 0.40 1.64769 33.79
10 2.895 Variable
11 -43.005 1.57 1.53071 55.69
12 * -7.771 variable
13 ∞ 0.30 1.51633 64.14
14 ∞ 0.50
15 ∞ 0.50 1.51633 64.14
16 ∞ 0.37
Image plane (imaging plane) ∞

Aspheric data first surface
k = 0.000
A4 = 2.19840e-03, A6 = -8.43252e-05, A8 = 1.56476e-06, A10 = -1.20001e-08
Second side
k = 0.405
A4 = 2.25368e-03, A6 = 5.48189e-05, A8 = -4.31752e-06
Third side
k = 0.000
A4 = -4.43614e-04
4th page
k = 0.000
A4 = -9.95014e-04, A6 = -2.76050e-05, A8 = 1.47640e-06, A10 = -2.09230e-08
6th page
k = 0.370
A4 = -2.52997e-03, A6 = 8.77165e-05, A8 = -5.70302e-05
7th page
k = 0.000
A4 = 1.29034e-04, A6 = 1.38889e-04, A8 = -5.35032e-05
12th page
k = 0.000
A4 = 6.34942e-04, A6 = -1.39741e-05, A8 = 4.07374e-07, A10 = -4.92068e-09

Zoom data
Wide angle Medium telephoto focal length 4.98 9.50 19.11
FNO. 2.97 4.18 6.70
Angle of view 2ω 84.73 44.28 22.67
fb (in air) 5.30 4.94 4.64
Total length (in air) 27.53 26.06 32.32

d4 10.84 4.41 0.72
d10 2.37 7.69 17.94
d12 3.90 3.55 3.25


Group focal length
f1 = -11.22 f2 = 8.69 f3 = 17.60

Numerical Example 9
Unit: mm

Surface data surface number rd nd υd
Object ∞ ∞
1 * -19.931 0.91 1.58313 59.38
2 * 5.486 1.42
3 * 7.599 1.46 1.63493 23.90
4 * 14.000 variable
5 (Aperture) ∞ 0.74
6 * 4.211 1.34 1.58313 59.46
7 * -11.573 0.10
9 7.504 1.22 1.58313 59.38
9 -11.387 0.40 1.64769 33.79
10 3.028 Variable
11 -88.831 1.56 1.53071 55.69
12 * -8.355 variable
13 ∞ 0.30 1.51633 64.14
14 ∞ 0.50
15 ∞ 0.50 1.51633 64.14
16 ∞ 0.37
Image plane (imaging plane) ∞

Aspheric data first surface
k = 0.000
A4 = 1.71115e-03, A6 = -6.65600e-05, A8 = 1.28944e-06, A10 = -1.06921e-08
Second side
k = -0.001
A4 = 1.30967e-03, A6 = 3.98471e-05, A8 = -3.33999e-06
Third side
k = 0.000
A4 = -8.55262e-04
4th page
k = 0.000
A4 = -9.95014e-04, A6 = -2.76050e-05, A8 = 1.47640e-06, A10 = -2.09230e-08
6th page
k = 0.370
A4 = -2.42427e-03, A6 = -1.70165e-05, A8 = -2.34177e-05
7th page
k = 0.000
A4 = 6.37360e-04, A6 = 4.81909e-05, A8 = -1.85450e-05
12th page
k = 0.000
A4 = 6.34942e-04, A6 = -1.39741e-05, A8 = 4.07374e-07, A10 = -4.92068e-09

Zoom data
Wide angle Medium Telephoto focal length 4.76 9.08 18.23
FNO. 2.91 4.09 6.54
Angle of view 2ω 86.99 45.92 23.42
fb (in air) 5.19 4.88 4.72
Total length (in air) 27.55 26.08 32.39

d4 10.84 4.42 0.72
d10 2.37 7.63 17.80
d12 3.77 3.45 3.25

Group focal length
f1 = -10.81 f2 = 8.66 f3 = 17.26

Numerical Example 10
Unit: mm

Surface data surface number rd nd υd
Object ∞ ∞
1 * -38.547 0.91 1.53071 55.69
2 * 3.422 1.50
3 * 6.240 1.70 1.63493 23.90
4 * 14.000 variable
5 (Aperture) ∞ 0.00
6 * 3.373 1.69 1.49700 81.54
7 * -10.068 0.10
8 * -10.093 1.00 1.68893 31.07
9 -15.326 0.80 1.68893 31.07
10 * 29.986 variable
11 ∞ 0.30 1.51633 64.14
12 ∞ 0.50
13 ∞ 0.50 1.51633 64.14
14 ∞ 0.37
Image plane (imaging plane) ∞

Aspheric data first surface
k = 0.000
A4 = -3.49485e-04, A6 = 2.80163e-05, A8 = -8.56328e-07, A10 = 1.08692e-08
Second side
k = -0.347
A4 = -2.13783e-03, A6 = 6.24157e-05, A8 = -7.24182e-06
Third side
k = 0.000
A4 = -1.00000e-03
4th page
k = 0.000
A4 = -6.82668e-04, A6 = -8.68917e-05, A8 = 1.15687e-05, A10 = -5.14153e-07
6th page
k = -0.474
A4 = 1.26305e-03, A6 = -7.10318e-05, A8 = 8.29015e-06
7th page
k = 0.000
A4 = 2.85991e-03, A6 = 2.04558e-04, A8 = -4.03691e-05
8th page
k = 0.000
A4 = 3.93695e-03, A6 = 4.07276e-04, A8 = -5.51515e-05
10th page
k = 0.000
A4 = 6.87412e-03, A6 = 4.78596e-04, A8 = 7.71144e-05

Zoom data
Wide angle Medium telephoto focal length 5.06 9.66 19.43
FNO. 3.27 4.34 6.64
Angle of view 2ω 83.82 44.48 22.39
fb (in air) 10.09 14.04 22.43
Total length (in air) 30.73 26.73 30.72

d4 12.95 5.00 0.60
d10 8.69 12.64 21.03


Group focal length
f1 = -9.92 f2 = 8.52

Numerical Example 11
Unit: mm

Surface data surface number rd nd υd
Object ∞ ∞
1 * -39.579 0.10 1.53071 55.69
2 * 3.414 1.50
3 * 6.244 1.78 1.63493 23.90
4 * 14.000 variable
5 (Aperture) ∞ 0.00
6 * 3.382 1.72 1.49700 81.54
7 * -10.093 0.10
8 * -9.747 1.00 1.68893 31.07
9 -15.326 0.80 1.68893 31.07
10 * 35.352 variable
11 ∞ 0.30 1.51633 64.14
12 ∞ 0.50
13 ∞ 0.50 1.51633 64.14
14 ∞ 0.37
Image plane (imaging plane) ∞

Aspheric data first surface
k = 0.000
A4 = -2.44295e-04, A6 = 2.15075e-05, A8 = -8.11541e-07, A10 = 1.34394e-08
Second side
k = -0.373
A4 = -1.65892e-03, A6 = 2.11303e-05, A8 = -6.30975e-06
Third side
k = 0.000
A4 = -1.00000e-03
4th page
k = 0.000
A4 = -8.15805e-04, A6 = -6.33765e-05, A8 = 1.00141e-05, A10 = -4.42234e-07
6th page
k = -0.474
A4 = 1.26124e-03, A6 = -6.39958e-05, A8 = 8.12203e-06
7th page
k = 0.000
A4 = 2.89920e-03, A6 = 2.12036e-04, A8 = -4.21957e-05
8th page
k = 0.000
A4 = 3.99596e-03, A6 = 4.04408e-04, A8 = -5.52953e-05
10th page
k = 0.000
A4 = 6.79577e-03, A6 = 4.57237e-04, A8 = 7.73831e-05

Zoom data
Wide angle Medium telephoto focal length 5.06 9.66 19.43
FNO. 3.26 4.33 6.62
Angle of view 2ω 83.22 44.39 22.38
fb (in air) 10.06 14.00 22.35
Total length (in air) 30.07 26.02 29.96

d4 13.01 5.02 0.60
d10 8.67 12.60 20.96

Group focal length
f1 = -9.96 f2 = 8.52

  Aberration diagrams at the time of focusing on an object point at infinity in Examples 1 to 11 are shown in FIGS. In these aberration diagrams, (a) is the wide-angle end, (b) is the intermediate focal length state, (c) is the spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration at the telephoto end. (CC) is shown. In each figure, “ω” indicates a half angle of view.

The values corresponding to conditional expressions are listed below.
(1) n _1n
(2) n _1p
(3) | ν _1n −ν _1p |
(4) Σd _1G / (ytan (2ω))
(5) d _1nw / d _1nc
(6) _fw / y
(7) d ₁₂ / | r _1nf |
(8) d ₁₂ / | r _1pr |
(9) d _t / y
(10) f _t / f _w
(11) _dw / y
(12) Σd _2G / (ytan (2ω))
(13) | f _air | / | f _1G |
(14) d _t / (ytan (2ω))
(15) d _w / (ytan (2ω))
(16) d _w3i tan (2ω) / y

Conditional Example 1 Example 2 Example 3
(1) 1.53 1.53 1.53
(2) 1.63 1.63 1.63
(3) 31.79 32.01 32.01
(4) 0.07 0.01 0.07
(5) 3.31 3.44 3.39
(6) 1.27 1.19 1.27
(7) 0.08 0.09 0.07
(8) 0.10 0.11 0.09
(9) 8.49 8.41 8.39
(10) 3.84 3.85 3.84
(11) 7.25 7.31 7.35
(12) 0.06 0.01 0.06
(13) 40.32 7.56 15.14
(14) 0.65 0.11 0.65
(15) 0.56 0.09 0.57
(16) 17.77 107.79 18.44


Example 4 Example 5 Example 6 Example 7
(1) 1.53 1.53 1.53 1.50
(2) 1.63 1.63 1.63 1.63
(3) 31.79 31.79 31.79 57.64
(4) 0.12 0.09 0.08 0.07
(5) 4.08 11.31 21.66 3.41
(6) 1.35 1.31 1.30 1.26
(7) 0.06 0.06 0.06 0.08
(8) 0.07 0.10 0.11 0.11
(9) 8.54 8.54 8.54 8.49
(10) 3.84 3.84 3.84 3.84
(11) 7.20 7.16 7.16 7.26
(12) 0.11 0.09 0.08 0.05
(13) 20.19 6.72 5.82 6.74
(14) 1.14 0.89 0.85 0.57
(15) 0.96 0.74 0.71 0.49
(16) 10.50 13.32 13.97 20.21


Example 8 Example 9 Example 10 Example 11
(1) 1.44 1.58 1.53 1.53
(2) 1.63 1.63 1.63 1.63
(3) 71.03 35.48 31.79 31.79
(4) 0.09 0.05 0.12 0.11
(5) 3.43 3.26 3.92 27.59
(6) 1.30 1.24 1.32 1.32
(7) 0.12 0.07 0.04 0.04
(8) 0.11 0.10 0.11 0.11
(9) 8.49 8.49 8.07 7.87
(10) 3.84 3.84 3.84 3.84
(11) 7.24 7.24 8.07 7.90
(12) 0.07 0.04 0.10 0.11
(13) 17.89 9.13 3.40 3.34
(14) 0.78 0.44 0.87 0.94
(15) 0.67 0.37 0.87 0.94
(16) 14.97 26.28 --- ---

  Further, in order to cut unnecessary light such as ghosts and flares, a flare stop other than the brightness stop may be arranged. The first lens group may be disposed at any position on the object side, between the first and second lens groups, between the second and third lens groups, the second, between the image planes, and between the third and image planes. The frame member may be configured to cut flare rays, or another member may be configured. Also, it may be printed directly on the optical system, painted, or bonded with a seal. The shape may be any shape such as a circle, an ellipse, a rectangle, a polygon, or a range surrounded by a function curve. Further, not only harmful light beams but also light beams such as coma flare around the screen may be cut.

  Each lens may be provided with an anti-reflection coating to reduce ghosts and flares. A multi-coat is desirable because it can effectively reduce ghost and flare. Infrared cut coating may be applied to the lens surface, cover glass, or the like.

  In order to prevent the occurrence of ghost and flare, it is common practice to apply an antireflection coating to the air contact surface of the lens. On the other hand, the refractive index of the adhesive is sufficiently higher than the refractive index of air on the cemented surface of the cemented lens. For this reason, the reflectance is often the same as or lower than that of a single-layer coating, and it is rare to apply a coating. However, if an anti-reflection coating is also applied to the joint surface, ghosts and flares can be further reduced, and still better images can be obtained.

  In recent years, high refractive index glass materials have become widespread and have been used extensively in camera optical systems due to their high aberration correction effects. However, when high refractive index glass materials are used as cemented lenses, reflection on the cemented surface is ignored. It becomes impossible. In such a case, it is particularly effective to provide an antireflection coating on the joint surface.

  Effective use of the bonding surface coat is disclosed in JP-A-2-27301, JP-A-2001-324676, JP-A-2005-92115, USP7116482, and the like. These documents particularly describe the cemented lens surface coating in the first group of the positive leading zoom lens, and the cemented lens surface in the first lens group having the positive refractive power of the present invention is also disclosed in these documents. You just have to do it. The coating material used is relatively high refractive index Ta2O5, TiO2, Nb2O5, ZrO2, HfO2, CeO2, SnO2, In2O3, ZnO, Y2O3, etc., depending on the refractive index of the base lens and the refractive index of the adhesive A coating material such as MgF2, SiO2, or Al2O3 having a relatively low refractive index may be appropriately selected and set to a film thickness that satisfies the phase condition.

As a matter of course, the coating on the bonding surface may be a multi-coat as in the coating on the air contact surface of the lens.
By appropriately combining two or more layers of coating materials and film thicknesses, it becomes possible to further reduce the reflectance and control the spectral characteristics and angular characteristics of the reflectance.
Needless to say, it is effective to coat the cemented surfaces other than the first lens group based on the same concept.

(Correction of distortion)
By the way, when the zoom lens of the present invention is used, image distortion is digitally corrected electrically. For this reason, the image height IH near the wide-angle end is reduced, and the effective image pickup area near the wide-angle end is shaped like a barrel.
The basic concept for digitally correcting image distortion will be described below.

  For example, as shown in FIG. 23, the magnification on the circumference (image height) of the radius R inscribed in the long side of the effective imaging surface around the intersection of the optical axis and the imaging surface is fixed. The standard for correction. Then, correction is performed by moving each point on the circumference (image height) of any other radius r (ω) in a substantially radial direction and concentrically so as to have the radius r ′ (ω). To do.

For example, in FIG. 23, a point P ₁ on the circumference of an arbitrary radius r ₁ (ω) located inside the circle of radius R is a radius r ₁ ′ (ω) circle to be corrected toward the center of the circle. Move to point P ₂ on the circumference. A point Q ₁ on the circumference of an arbitrary radius r ₂ (ω) located outside the circle of radius R is a radius r ₂ ′ (ω) circumference to be corrected in a direction away from the center of the circle. It is moved to the point Q ₂ of the above.

Here, r ′ (ω) can be expressed as follows.
r ′ (ω) = α · f · tan ω (0 ≦ α ≦ 1)
However,
ω is the half angle of view of the subject,
f is the focal length of the imaging optical system (in the present invention, the zoom lens),
α is 0 or more and 1 or less.

Here, if the ideal image height corresponding to the circle (image height) of the radius R is Y,
α = R / Y = R / (f · tan ω)
It becomes.

  The optical system is ideally rotationally symmetric with respect to the optical axis, that is, distortion is also generated rotationally symmetric with respect to the optical axis. Therefore, as described above, when the optically generated distortion aberration is electrically corrected, the radius inscribed in the long side of the effective imaging surface around the intersection of the optical axis and the imaging surface on the reproduced image. The magnification on the circumference of the circle of R (image height) is fixed, and the other points on the circumference of the circle (image height) of radius r (ω) are moved in a substantially radial direction to obtain a radius r ′ ( If correction can be performed by moving the concentric circles so that ω), it is considered advantageous in terms of data amount and calculation amount.

  However, the optical image is no longer a continuous amount (due to sampling) when captured by the electronic image sensor. Therefore, strictly speaking, the circle with the radius R drawn on the optical image is not an accurate circle unless the pixels on the electronic image sensor are arranged radially.

  That is, in the shape correction of the image data represented for each discrete coordinate point, there is no circle that can fix the magnification. Therefore, it is preferable to use a method of determining the coordinates (Xi ′, Yj ′) of the movement destination for each pixel (Xi, Yj). When two or more points (Xi, Yj) have moved to the coordinates (Xi ′, Yj ′), the average value of the values possessed by each pixel is taken. If there is no moving point, interpolation may be performed using the values of the coordinates (Xi ′, Yj ′) of some surrounding pixels.

  Such a method is particularly distorted with respect to the optical axis due to manufacturing errors of an optical system and an electronic imaging device in an electronic imaging apparatus having a zoom lens, and the circle with the radius R drawn on the optical image is It is effective for correction when it becomes asymmetric. Further, it is effective for correction when a geometric distortion or the like occurs when a signal is reproduced as an image in an image sensor or various output devices.

  In the electronic imaging apparatus of the present invention, in order to calculate the correction amount r ′ (ω) −r (ω), r (ω), that is, the relationship between the half field angle and the image height, or the real image height r and the ideal image height. The relationship between r ′ / α may be recorded on a recording medium built in the electronic imaging apparatus.

  Note that the radius R preferably satisfies the following conditional expression so that the image after distortion correction does not have an extremely short amount of light at both ends in the short side direction.

0 ≦ R ≦ 0.6Ls
However, Ls is the length of the short side of the effective imaging surface.

Preferably, the radius R satisfies the following conditional expression.
0.3Ls≤R≤0.6Ls
Furthermore, it is most advantageous to make the radius R coincide with the radius of the inscribed circle in the short side direction of the substantially effective imaging surface. In the case of correction in which the magnification is fixed in the vicinity of the radius R = 0, that is, in the vicinity of the axis, there is a slight disadvantage in terms of image quality, but the effect of reducing the size is secured even if the angle of view is widened. it can.

The focal length section that needs to be corrected is divided into several focal zones. And approximately near the telephoto end in the divided focal zone,
r ′ (ω) = α · f · tan ω
You may correct | amend with the same correction amount as the case where the correction result which satisfies is obtained.

  However, in that case, some barrel distortion remains at the wide-angle end in the divided focal zone. Further, if the number of divided zones is increased, it becomes unnecessary to store extraneous data necessary for correction on the recording medium, which is not preferable. Therefore, one or several coefficients related to each focal length in the divided focal zone are calculated in advance. This coefficient may be determined on the basis of simulation or actual measurement.

And approximately near the telephoto end in the divided zone,
r ′ (ω) = α · f · tan ω
It is also possible to calculate a correction amount when a correction result satisfying the above is obtained, and uniformly multiply the correction amount for each focal distance to obtain a final correction amount.

By the way, if there is no distortion in the image obtained by imaging an object at infinity,
f = y / tan ω
Is established.
Where y is the height of the image point from the optical axis (image height), f is the focal length of the imaging system (in the present invention, the zoom lens), and ω is the image point connected from the center on the imaging surface to the y position. It is an angle (subject half field angle) with respect to the optical axis in the corresponding object direction.

If the imaging system has barrel distortion,
f> y / tan ω
It becomes. That is, if the focal length f of the imaging system and the image height y are constant, the value of ω increases.

(Digital camera)
24 to 26 are conceptual diagrams of the configuration of the digital camera according to the present invention in which the zoom lens as described above is incorporated in the photographing optical system 141. FIG. 24 is a front perspective view showing the external appearance of the digital camera 140, FIG. 25 is a rear front view thereof, and FIG. 26 is a schematic cross-sectional view showing the configuration of the digital camera 140. However, in FIGS. 24 and 26, the photographing optical system 141 is not retracted. In this example, the digital camera 140 includes a photographing optical system 141 having a photographing optical path 142, a finder optical system 143 having a finder optical path 144, a shutter button 145, a flash 146, a liquid crystal display monitor 147, a focal length change button 161, When the photographic optical system 141 is retracted, including the setting change switch 162, the photographic optical system 141, the finder optical system 143, and the flash 146 are covered with the cover 160 by sliding the cover 160. Then, when the cover 160 is opened and the camera 140 is set to the shooting state, the shooting optical system 141 is in the non-collapsed state of FIG. Photographing is performed through the optical system 141, for example, the zoom lens of the first embodiment. An object image formed by the photographic optical system 141 is formed on the imaging surface of the CCD 149 through a low-pass filter F and a cover glass C that are provided with a wavelength band limiting coat. The object image received by the CCD 149 is displayed as an electronic image on a liquid crystal display monitor 147 provided on the back of the camera via the processing means 151. Further, the processing means 151 is connected to a recording means 152 so that a photographed electronic image can be recorded. The recording unit 152 may be provided separately from the processing unit 151, or may be configured to perform recording / writing electronically using a flexible disk, a memory card, an MO, or the like. Further, instead of the CCD 149, a silver salt camera in which a silver salt film is arranged may be configured.

  Further, a finder objective optical system 153 is disposed on the finder optical path 144. The finder objective optical system 153 includes a plurality of lens groups (three groups in the figure) and two prisms, and includes a zoom optical system whose focal length changes in conjunction with the zoom lens of the photographing optical system 141. The object image formed by the finder objective optical system 153 is formed on the field frame 157 of the erecting prism 155 that is an image erecting member. Behind the erecting prism 155, an eyepiece optical system 159 that guides the erect image to the observer eyeball E is disposed. A cover member 150 is disposed on the exit side of the eyepiece optical system 159.

  The digital camera 140 configured in this way has the imaging optical system 141 according to the present invention, which is extremely thin when retracted, and has high zooming performance and extremely stable imaging performance in the entire zooming range. A small size and wide angle of view can be realized.

The zoom lens may be configured to be separable from the camera body that holds the image sensor, and the zoom lens may be configured as an interchangeable lens.
Recently, in addition to single-lens reflex cameras equipped with a quick return mirror in the camera body, interchangeable lens cameras that eliminate the quick return mirror are gaining popularity. Is reasonably short, it is preferably used as an interchangeable lens for a camera without such a quick return mirror.

(Internal circuit configuration)
FIG. 27 is a block diagram showing the internal circuitry of the main part of the digital camera 140. In the following description, the processing means includes, for example, the CDS / ADC unit 124, the temporary storage memory 117, the image processing unit 118, and the like, and the storage means includes, for example, the storage medium unit 119.

  As shown in FIG. 27, the digital camera 140 is connected to the operation unit 112, the control unit 113 connected to the operation unit 112, and the control signal output port of the control unit 113 via buses 114 and 115. An imaging drive circuit 116, a temporary storage memory 117, an image processing unit 118, a storage medium unit 119, a display unit 120, and a setting information storage memory unit 121 are provided.

  The temporary storage memory 117, the image processing unit 118, the storage medium unit 119, the display unit 120, and the setting information storage memory unit 121 are configured so that data can be input or output with each other via the bus 122. In addition, a CCD 149 and a CDS / ADC unit 124 are connected to the imaging drive circuit 116.

  The operation unit 112 includes various input buttons and switches, and is a circuit that notifies the control unit of event information input from the outside (camera user) via these input buttons and switches.

  The control unit 113 is a central processing unit composed of, for example, a CPU and the like. The control unit 113 includes a program memory (not shown) and is input from the camera user via the operation unit 112 according to a program stored in the program memory. This is a circuit that controls the entire digital camera 140 in response to an instruction command.

  The CCD 149 receives an object image formed through the photographing optical system 141 according to the present invention. The CCD 149 is an image pickup element that is driven and controlled by the image pickup drive circuit 116, converts the light amount of each pixel of the object image into an electrical signal, and outputs the electric signal to the CDS / ADC unit 124.

  The CDS / ADC unit 124 amplifies the electric signal input from the CCD 149 and performs analog / digital conversion, and temporarily stores the raw video data (Bayer data, hereinafter referred to as RAW data) that has just been subjected to the amplification and digital conversion. This is a circuit for outputting to the storage memory 117.

  The temporary storage memory 117 is a buffer made of, for example, SDRAM or the like, and is a memory device that temporarily stores the RAW data output from the CDS / ADC unit 124. The image processing unit 118 reads out the RAW data stored in the temporary storage memory 117 or the RAW data stored in the storage medium unit 119, and performs various corrections including distortion correction based on the image quality parameter designated from the control unit 113. It is a circuit that performs image processing electrically.

  The recording medium unit 119 detachably mounts a card-type or stick-type recording medium made of, for example, a flash memory, and RAW data transferred from the temporary storage memory 117 to the card-type or stick-type flash memory. This is a control circuit of an apparatus for recording and holding image data processed by the image processing unit 118.

  The display unit 120 includes a liquid crystal display monitor, and is a circuit that displays an image, an operation menu, and the like on the liquid crystal display monitor. The setting information storage memory unit 121 stores a ROM unit in which various image quality parameters are stored in advance, and an image quality parameter selected by an input operation of the operation unit 112 among the image quality parameters read from the ROM unit. RAM section is provided. The setting information storage memory unit 121 is a circuit that controls input and output to these memories.

  In the digital camera 140 configured in this way, the imaging optical system 141 has a sufficiently wide angle range and a compact configuration according to the present invention, and the imaging performance is extremely stable at a high zoom ratio and in a full zoom ratio range. Therefore, high performance, downsizing, and wide angle of view can be realized. In addition, fast focusing operation on the wide-angle side and the telephoto side is possible.

  As described above, the zoom lens according to the present invention is useful as a zoom lens that is advantageous in wide angle, high zoom ratio, size reduction, and cost reduction.

G1 ... 1st lens group G2 ... 2nd lens group G3 ... 3rd lens group S ... Brightness stop F ... Low pass filter C ... Cover glass I ... Image surface 112 ... Operation part 113 ... Control part 114 ... Bus 115 ... Bus 116 Image pickup drive circuit 117 ... Temporary storage memory 118 ... Image processing unit 119 ... Storage medium unit 120 ... Display unit 121 ... Setting information storage memory unit 122 ... Bus 124 ... CDS / ADC unit 140 ... Digital camera 141 ... Shooting optical system 142 ... Imaging optical path 143 finder optical system 144 finder optical path 145 shutter button 146 flash 147 liquid crystal display monitor 149 CCD
150: cover member 151 ... processing means 152 ... recording means 153 ... finder objective optical system 155 ... erecting prism 157 ... field frame 159 ... eyepiece optical system 160 ... cover 161 ... focal length change button 162 ... setting change switch

Claims (16)

In order from the object side, in a zoom lens having a first lens group having a negative refractive power and a second lens group having a positive refractive power,
The zoom lens according to claim 1, wherein the first lens group includes a first lens having a negative refractive power and a second lens having a positive refractive power, and satisfies the following conditional expression.
n _1n ≦ 1.70 (1)
n _1p ≦ 1.70 (2)
| Ν _1n −ν _1p | ≧ 31 (3)
However,
n _1n is the refractive index of the d-line of the first lens having negative refractive power in the first lens group,
ν _1n is the Abbe number of the first lens having negative refractive power in the first lens group,
n _1p is the refractive index of the d-line of the second lens having positive refractive power in the first lens group,
ν _1p is the Abbe number of the second lens having positive refractive power in the first lens group,
It is. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
Σd _1G /(ytan(2ω))≦0.3 (4)
However,
Σd _1G is the total length of the first lens group,
y is the maximum image height at the image plane in the zoom lens;
ω is the half angle of view at the wide-angle end of the zoom lens,
It is. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
d _1nw / d _1nc ≧ 3.0 (5)
f _w /y≦1.4 (6)
However,
d 1 _nw is the lens thickness at the position where the outermost principal ray at the wide-angle end of the first lens unit having the negative refractive power _passes in the first lens group,
d 1 _nC is the lens thickness on the optical axis of the first lens having negative refractive power in the first lens group,
_fw is the focal length at the wide-angle end of the zoom lens,
It is.   4. The zoom according to claim 1, wherein at least one of the first lens having a negative refractive power and the second lens having a positive refractive power in the first lens group is made of a resin lens. 5. lens.   Of the first lens having negative refractive power and the second lens having positive refractive power in the first lens group, at least one lens surface is an aspherical surface, and the outermost principal ray passes through the aspherical surface from the lens center. 4. The zoom lens according to claim 1, wherein the shape monotonously increases or decreases monotonously in the optical axis direction toward the position. 5. The zoom lens according to claim 4, wherein the following conditional expression is satisfied.
d ₁₂ / | r _1nf | ≦ 0.2 (7)
d ₁₂ / | r _1pr | ≦ 0.2 (8)
However,
d ₁₂ is an air gap between the negative first lens and a positive second lens in the first lens group,
r _1nf is a radius of curvature of the negative first lens in the first lens group on the object side surface;
r _1pr is a radius of curvature at the image side surface of the positive second lens in the first lens group,
It is. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
d _t /y≦8.5 (9)
f _t / f _w ≧ 3.0 (10)
However,
_dt is the total length at the telephoto end of the zoom lens,
f _t is the focal length of the zoom lens telephoto end,
It is. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
d _w /y≦8.1 (11)
f _t / f _w ≧ 3.0 (10)
However,
_dw is the total length at the wide-angle end of the zoom lens,
It is.   The zoom lens according to any one of claims 1 to 8, wherein all the lenses constituting the zoom lens are composed of lenses having a refractive index of 1.7 or less. The zoom lens according to claim 9, wherein the following conditional expression is satisfied.
Σd _2G /(ytan(2ω))≦0.35 (12)
However,
Σd _2G is the total length of the second lens group,
y is the maximum image height at the imaging plane of the zoom lens,
It is. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
| F _air | / | f _1G | ≧ 15 (13)
However,
f _air is a focal length of an air lens formed between the first lens and the second lens,
f _1G is the focal length of the first lens group,
It is. The zoom lens according to any one of claims 1 to 11, wherein the following conditional expression is satisfied.
d _t /(ytan(2ω))≦1.7 (14) The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
d _w / (ytan (2ω)) ≦ 1.7 (15) In order from the object side, in a zoom lens having a first lens group with negative refractive power, a second lens group with positive refractive power, and a third lens group with positive refractive power,
The zoom lens according to claim 1, wherein the first lens group includes a first lens having a negative refractive power and a second lens having a positive refractive power, and satisfies the following conditional expression.
n _1n ≦ 1.70 (1)
n _1p ≦ 1.70 (2)
| Ν _1n −ν _1p | ≧ 31 (3)
However,
n _1n is the refractive index of the first lens of d-line having negative refractive power in the first lens group,
ν _1n is the Abbe number of the first lens having negative refractive power in the first lens group,
n _1p is the refractive index of the second lens of the d-line with positive refractive power in the first lens group,
ν _1p is the Abbe number of the second lens having positive refractive power in the first lens group,
It is. The zoom lens according to claim 14, wherein the following conditional expression is satisfied.
d _w3i tan (2ω) / y ≧ 5 (16)
However,
d _w3i is the air space between the image side surface and the image forming surface of the third lens group at the wide angle end;
It is. The zoom lens according to any one of claims 1 to 15,
An image pickup apparatus, comprising: an image pickup element that is disposed on an image side of the zoom lens and converts an optical image formed by the zoom lens into an electric signal.

Images