JP2007078801A - Zoom lens and electronic imaging apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens which can be made very thin in a depth direction when being stored (collapsed) and is capable of very and stably improving the imaging performance throughout a variable magnification range. <P>SOLUTION: The zoom lens comprises, in order from an object side; a first lens group G1 which has a negative refracting power and comprises two lens components of a negative lens component L11 and a positive lens component L12; and a second lens group G2 which has a positive refracting power and comprises one lens component having a plurality of lens elements L21 and L22 joined, and a relative space between the lens groups is changed for variable magnification or focusing. The negative lens component L11 of the lens group G1 has an image-side surface formed into an aspherical surface of which the diverging action is enhanced as going farther from an optical axis. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a zoom lens whose depth becomes extremely thin when housed and an electronic imaging apparatus including the same.

  In recent years, digital cameras (electronic cameras) have attracted attention as next-generation cameras that can replace 35 mm film (commonly known as Leica version) cameras. Furthermore, it has come to have a number of categories in a wide range from a high-function type for business use to a portable popular type. In the present invention, focusing on the category of portable popular type, it is aimed to provide a technology for realizing a video camera and a digital camera with a small depth while ensuring a high image quality.

  The greatest bottleneck in reducing the depth direction of the camera is the thickness from the most object-side surface to the imaging surface of the optical system, particularly the zoom lens system. Recently, it has become the mainstream to adopt a so-called collapsible lens barrel that protrudes the optical system from the camera body during shooting and stores the optical system in the camera body when carried. However, the thickness when the optical system is retracted varies greatly depending on the lens type and filter used. In particular, to set high specifications such as the zoom ratio and F value, the so-called positive leading zoom lens, in which the lens unit closest to the object side has positive refractive power, has a large thickness and dead space for each lens element. However, the thickness is not very thin (see Patent Document 1).

The negative leading type zoom lens having 2 to 3 groups is particularly advantageous in this respect, but it is also retractable when the number of elements in the group is large, the thickness of the element is large, or the most object side lens is a positive lens. (See Patent Document 2 or 3). Patent Document 4 and the like are examples of what is currently known and is suitable for electronic imaging devices and has good imaging performance including zoom ratio, angle of view, F number, etc., and the possibility of making the collapsible thickness the smallest. There is a thing of description. When the entrance pupil position of the first group is made shallower, the diameter becomes smaller, and as a result, the first group itself can be made thinner. For that purpose, the magnification of the second group must be increased, that is, the refractive power must be increased. First, the imaging performance must be sacrificed, or the number of constituent elements must be increased to reduce the depth.
Japanese Patent Laid-Open No. 11-258507 Japanese Patent Laid-Open No. 11-52246 JP-A-11-142734 JP 9-33810 A

  The present invention provides a zoom lens in which the thickness in the depth direction can be extremely reduced when the lens is retracted (when retracted), and the imaging performance can be extremely stably increased in the entire zoom range. The purpose is that.

  In order to achieve the above object, a zoom lens according to the present invention comprises, in order from the object side, a lens group A having negative refractive power and two lens components, a negative lens component and a positive lens component, and a positive refraction. In a zoom lens that includes a lens group B composed of a single lens component having a force and a plurality of lens elements joined, and the relative distance between the lens groups changes during zooming or focusing, The lens component is formed of an aspherical surface whose diverging action becomes stronger as the image-side surface moves away from the optical axis. However, the lens component is a lens component in which only the lens surface on the most object side and the lens surface on the most image side of the lens component are in contact with air and there is no air gap between them. Unit.

  In addition, the zoom lens according to the present invention includes, in order from the object side, a lens group A including two lens components having a negative refractive power and a negative lens component and a positive lens component, and a plurality of positive refractive powers. In a zoom lens that includes a lens group B composed of one positive lens component to which lens elements are joined, and whose relative distance changes during zooming or focusing, all optical elements constituting the lens group A Of the refracting surfaces, the number of aspheric surfaces is 50% or less. However, the lens component is a lens component in which only the lens surface on the most object side and the lens surface on the most image side of the lens component are in contact with air and there is no air gap between them. Unit.

  In addition, the zoom lens according to the present invention includes, in order from the object side, a lens group A including two lens components having a negative refractive power and a negative lens component and a positive lens component, and a plurality of positive refractive powers. In a zoom lens including a lens group B composed of one positive lens component to which lens elements are cemented, and the relative interval of each lens group changes upon zooming or focusing, the positive lens component of the lens group A has a refractive index. 1. A zoom lens including a positive lens made of a medium of 87 or more. However, the lens component is a lens component in which only the lens surface on the most object side and the lens surface on the most image side of the lens component are in contact with air and there is no air gap between them. Unit.

  According to the present invention, the imaging performance is extremely stable and high in the entire zooming range even if the total number of lenses is reduced to reduce the thickness in the depth direction when the lens is retracted (when retracted). Zoom lenses and electronic imaging devices can be provided.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings, and the operational effects of the present invention will be described prior to that.
The zoom lens according to the present invention includes, in order from the object side, a lens group A having two refractive index components, a negative lens component and a positive lens component, and a positive lens adjacent to the image side of the lens group A. The zoom lens includes a lens unit B including a single lens component having a refracting power and a plurality of lens elements cemented, and the relative interval of each lens unit is basically a zoom lens that changes by zooming or focusing. . In the present invention, the diverging action of the at least one negative lens component of the lens group A becomes stronger as the image side surface moves away from the optical axis. That is, it is preferable that the aspherical surface has a gentle (large) curvature radius.

  That is, the lens group B is composed of one lens component, and at least the image side surface of the negative lens component of the lens group A is composed of an aspheric surface whose radius of curvature becomes gentler as the distance from the optical axis increases. For example, it is easy to make the depth when retracted extremely thin while ensuring high imaging performance. Here, if the reason for introducing an aspherical surface in which the radius of curvature becomes gentler as the image side surface of the negative lens component of the lens group A is further away from the optical axis is further described, aberration correction is performed slightly on the object side in the center of the lens group A. By providing a high-performance surface, it is possible to correct on-axis and off-axis aberrations, astigmatism, coma aberration, and distortion aberration in a balanced manner. This makes it possible to reduce the number of aspheric surfaces or to increase the ease of manufacturing other aspheric surfaces, which is advantageous in terms of cost and productivity. Furthermore, by using an aspherical surface in which the image surface side of the negative lens component of the lens group A is a concave surface, and the curvature radius becomes gentler as the surface is away from the optical axis, the paraxial power of this surface can be increased. This is preferable because points are arranged on the object side to facilitate the zoom configuration (the amount of movement of the group can be reduced).

  Alternatively, it is preferable that the number of aspheric surfaces among all the optical refractive surfaces constituting the lens group A is 50% or less. In order to achieve the object, it is desirable to introduce an aspherical surface into the lens group A. However, even if the number of surfaces is increased to a certain extent, the cost increases and the productivity is lowered, resulting in no overall effect. It is only necessary to apply an aspherical surface to the number of surfaces that is 50% or less of all the optically refracting surfaces constituting the lens group A. In particular, as described above, it is preferable that the image side surface of the negative lens is aspherical, and further, the other surface of the lens group A is formed of a spherical surface, thereby improving the imaging performance and reducing the cost and productivity. A configuration that is not disadvantageous can be adopted.

  Alternatively, the positive lens component of the lens group A preferably includes a positive lens made of a medium having a refractive index of 1.87 or more. The Petzval sum (1 / Σf · n) tends to increase toward the positive side as the total length of the optical system is shortened and the collapsible thickness is decreased. In order to correct this, the refractive index is added to the positive lens component in the lens group A. It is better to use at least one positive lens having a medium of at least 1.87 or more.

Or it is preferable to satisfy the following conditions.
0.8 <ΣT / fw <2.5 (1)
Where ΣT is the sum of the distances on the optical axis from the most object-side surface to the most image-side surface of all lens groups, and fw is the focal length of the entire system at the wide-angle end.
According to this configuration, field curvature and astigmatism can be corrected relatively easily and satisfactorily, and can be thinned when retracted. If the upper limit is exceeded, even if the number of lens components is saved and the imaging performance is improved, the thickness cannot be reduced. Below the lower limit, even if the number of lenses is increased, the correction force due to the difference in the passing light height of the light flux at the entrance exit surface of each group is weakened, and field curvature or astigmatism tends to occur.

Moreover, it is better if the following conditions are satisfied.
1.0 <ΣT / fw <2.2 (1-1)

Furthermore, it is best to satisfy the following conditions.
1.4 <ΣT / fw <1.9 (1-2)

Or it is preferable to satisfy the following conditions.
0.4 <fR / | fA | <1.2 (2)
Here, fA is the focal length of the lens group A, and fR is the combined focal length at the wide-angle end of all the lens groups arranged on the image side of the lens group A. In order to shorten the total length, it is effective to shorten the combined focal length at the wide-angle end of all the lens units arranged on the image side from the lens unit A. It tends to bend from the imaging position to the object side. If the upper limit is exceeded, the total length tends to be longer.

Moreover, it is better if the following conditions are satisfied.
0.6 <fR / | fA | <1.0 (2-1)

Furthermore, it is best to satisfy the following conditions.
0.7 <fR / | fA | <0.9 (2-2)

Or it is preferable to satisfy the following conditions.
1.20 <| βRT | <2.30 (3)
However, βRT is a combined magnification of all the lens units disposed on the image side from the lens unit A when the telephoto end infinity object point is focused. In order to ensure a high zoom ratio while keeping the total length short, it is better to increase the combined magnification (negative value) of all the lens units arranged on the image side from the lens unit A. If the lower limit value is not reached, the total length at the wide-angle end becomes longer, and if the upper limit value is exceeded, each aberration tends to be deteriorated mainly with respect to spherical aberration, axial chromatic aberration and the like.

Moreover, it is better if the following conditions are satisfied.
1.30 <| β2T | <1.90 (3-1)

Furthermore, it is best to satisfy the following conditions.
1.20 <| β2T | <1.85 (3-2)
1.40 <| β2T | <1.75 (3-3)

Alternatively, it is preferable that the following conditions are satisfied with respect to the movement of the lens unit during zooming.
0.17 <(D12W−D12T) / (fw · γ ² ) <0.45 (4)
Where D12W and D12T are the air spacing on the optical axis between the lens group A at the wide-angle end and the telephoto end and the lens group adjacent to the image side, respectively, and γ is the entire system at the telephoto end when focusing on an object point at infinity. The focal length to wide-angle end ratio (so-called zoom ratio), fw is the focal length of the entire system at the wide-angle end. Aberration correction is advantageous when the upper limit is exceeded, but the off-axis ray height in the lens group A becomes high at the wide-angle end, and the diameter of the lens group A tends to enlarge, which increases the thickness of each lens component. Contrary. If it is below the lower limit, it is advantageous for thinning, but the combined power of the lens group A and the lens group disposed on the image side must be increased in power, coupled with the small number of components. There are problems such as difficulty in correcting each aberration and increased sensitivity to decentration.

The following conditions should be satisfied.
0.19 <(D12W−D12T) / (fw · γ ² ) <0.30 (4-1)

Furthermore, it is best to satisfy the following conditions.
0.21 <(D12W−D12T) / (fw · γ ² ) <0.27 (4-2)

Or it is preferable to satisfy the following conditions.
0.06 <d11 / fw <0.53 (5)
Here, fw is the focal length of the entire system at the wide-angle end, and d11 is the air space on the optical axis between the negative lens component and the positive lens component of the negative lens group A. If the upper limit value is exceeded, the retractable thickness tends to be thick, and if the lower limit value is not reached, the correction force due to the difference in the passing light height of the light beam on the exit surface of the group becomes weak and astigmatism tends to deteriorate.

Moreover, it is better if the following conditions are satisfied.
0.10 <d11 / fw <0.40 (5-1)

In addition, it is best if the following conditions are met.
0.20 <d11 / fw <0.35 (5-2)

In the present invention, the lens group A has a positive lens, further has a negative lens on the object side, and the refractive index and Abbe number of the medium constituting each of the positive lens and the negative lens are n1p, ν1p, When n1n and ν1n,
0.08 <n1p-n1n <0.35 (6)
5 <ν1n−ν1p <25 (7)
Good to be satisfied. Considering aberrations other than curvature of field for the negative lens, it is better to keep the refractive index as high as possible, but it is better not to make it higher than the positive lens. If the lower limit value of condition (6) is not reached, the spherical aberration at the telephoto end and the coma aberration at the wide angle end will exceed the upper limit value, and the curvature of field tends to deteriorate. Condition (7) stipulates the difference in Abbe number between the negative lens and the positive lens, but if either of the upper and lower limits is exceeded, the lateral chromatic aberration at the wide-angle end, the longitudinal chromatic aberration at the telephoto end, and the chromatic aberration of the spherical aberration are likely to deteriorate. .

Moreover, it is better if the following conditions are satisfied.
0.12 <n1p-n1n <0.33 (6-1)
10 <ν1n−ν1p <24 (7-1)

In addition, it is best if the following conditions are met.
0.18 <n1p-n1n <0.27 (6-2)
14 <ν1n−ν1p <22 (7-2)

Or it is preferable to satisfy the following conditions.
0.66 <(R23 + R21) / (R23−R21) <1.5 (8)
R21 and R23 are radii of curvature on the optical axis of the most object-side surface and the most image-side surface of the lens group B, respectively. Each lens element of the lens group B tends to have a high relative eccentricity sensitivity. Therefore, when a plurality of lens elements are joined to each other, it is easy to obtain high eccentricity adjustment accuracy. In general, when two or more lens elements are joined, the degree of freedom of aberration correction is reduced, and it tends to be difficult to bring all aberrations to a satisfactory level. Therefore, the shape factor of the cemented lens is preferably set as in the condition (8). If the upper limit is exceeded, correction of spherical aberration tends to be difficult, and if the lower limit is not reached, correction of coma and astigmatism tends to be difficult.

Moreover, it is better if the following conditions are satisfied.
0.69 <(R23 + R21) / (R23−R21) <1.2 (8-1)

Furthermore, it is best to satisfy the following conditions.
0.72 <(R23 + R21) / (R23−R21) <1.0 (8-2)

Or it is preferable to satisfy the following conditions.
ν2p> 65 (9)
Here, ν2p is the Abbe number (d-line reference) of the medium constituting the positive lens included in the lens group B. If the value is below the lower limit, each aberration tends to be deteriorated with a focus on chromatic aberration.

Moreover, it is better if the following conditions are satisfied.
ν2p> 70 (9-1)

Furthermore, it is best to satisfy the following conditions.
ν2p> 80 (9-2)

Alternatively, it is preferable that the lens group B includes a cemented lens of a positive lens and a negative lens and satisfies the following conditions.
−1.5 <fw / R22 <−0.50 (10)
Here, R22 is the radius of curvature of the cemented surface of the lens group B on the optical axis. If the upper limit value is exceeded, axial chromatic aberration tends to be undercorrected, and if the lower limit value is not reached, chromatic aberration of spherical aberration tends to occur.

Moreover, it is better if the following conditions are satisfied.
−1.0 <fw / R22 <−0.75 (10-1)

Furthermore, it is best to satisfy the following conditions.
−0.94 <fw / R22 <−0.82 (10-2)

Further, an electronic image pickup apparatus of the present invention includes the zoom lens and an electronic image pickup element disposed on the image side of the zoom lens.
In addition, another electronic imaging device according to the present invention has a positive refractive power and a lens group A having two negative lens components, a negative lens component and a positive lens component, in order from the object side. A zoom lens that includes a lens group B composed of a single lens component in which a plurality of lens elements are joined, and the relative distance between the lens groups is changed by zooming or focusing, and is disposed on the image side of the zoom lens. An image that can be output as image data whose shape has been changed by processing image data obtained by capturing an image formed through the zoom lens with the electronic image sensor. An electronic imaging device including a processing unit. In this way, the optical system portion can be made smaller or thinner by positively producing barrel-shaped distortion aberration and correcting it by image processing. In the case of having barrel distortion, information having a wider angle of view than the ideal imaging state is also taken in. Therefore, if the barrel distortion is positively generated and the distortion is corrected by image processing, the design with a narrower angle of view becomes possible, and the lens can be made thinner.

In the present invention, it is preferable that the following condition is satisfied when the zoom lens is focused on any object distance of 50 times or more of fw.
0.75 <y * ₀₈ / (fw · tan _ω08w ) <0.96 (11)
However, if the distance from the center of the electronic image sensor to the farthest point corresponding to the point farthest from the center of the image after distortion correction is y * ₁₀ , y * ₀₈ = 0.8y * ₁₀ , _ω08w is This is an angle formed by a light beam corresponding to an image point connected at a position y * ₀₈ away from the center on the imaging surface at the wide-angle end and the optical axis in the object point direction. When an image is formed on the electronic image pickup device intentionally having a large barrel distortion at a focal length near the wide-angle end of the zoom lens, the effective diameter of the lens group A, which tends to have the largest diameter, is small. As a result, the thickness can be reduced.

  Further, when the lens group A is composed of only two lens components, a negative lens component and a positive lens component, the distance between the two lens components must be a certain value or more for correcting distortion. However, by allowing the amount of distortion, this distance is not so necessary, and this also contributes to the reduction in thickness. It is also advantageous for correcting astigmatism. Then, the barrel-distorted image is photoelectrically converted into image data by the image sensor, and finally subjected to processing corresponding to a shape change in the signal processing system of the electronic imaging device, so that the When the image data output from the electronic imaging device is reproduced on some display device, the distortion is corrected and an image substantially similar to the subject shape is obtained.

If there is no distortion in the image obtained by imaging an infinite object,
f = y * / tan ω = y / tan ω
Is established. Where y * is the height of the image point from the optical axis, y is the height of the ideal image point (image point when the optical system has no distortion) from the optical axis, f is the focal length of the imaging system, ω is an angle formed with the optical axis in the direction of the object point corresponding to the image point connected to a position y * away from the center on the imaging surface. If the imaging system has barrel distortion,
f> y * / tan ω
It becomes. That is, if f and y are constant, ω is a large value.

  That is, the condition (11) defines the degree of barrel distortion at the zoom wide-angle end. If the upper limit is exceeded, it is difficult to reduce the size and thickness. Below the lower limit, when image distortion due to distortion of the optical system is corrected by image processing, the enlargement ratio in the radial direction of the peripheral portion of the angle of view becomes too high, and the sharpness deterioration of the peripheral portion of the image becomes conspicuous. In this way, the purpose of introducing distortion correction intentionally in an optical system and correcting the distortion by electrically processing the image after imaging with an electronic image sensor is to reduce the size of the optical system or increase the angle (distortion). (The vertical angle of view is more than 38 °).

Moreover, it is better if the following conditions are satisfied.
0.80 <y * ₀₈ / (fw · tan _ω08w ) <0.95 (11-1)

Furthermore, it is best to satisfy the following conditions.
0.85 <y * ₀₈ / (fw · tan _ω08w ) <0.94 (11-2)

It is preferable that the following condition is satisfied when the zoom lens is focused on any object distance of 50 times or more of fw.
0.50 <(dy * / dy) _{y * 08} / (dy * / dy) _{y * 00} <0.90 (12)
However, (dy * / dy) _{y * 08} represents the differential amount dy * / dy at y * ₀₈ , and (dy * / dy) y * ₀₀ represents the differential amount dy * / dy on the paraxial axis. The actual image height y * is a function of the ideal image height y, but in local y where the differential value dy * / dy is larger than a certain level, the local magnification at the time of distortion correction increases. Thus, it becomes difficult to obtain a predetermined resolving power at that portion. Below the lower limit, the local enlargement ratio at the time of distortion correction becomes too large, and it becomes difficult to obtain a predetermined resolving power at that portion. When the upper limit is exceeded, it becomes difficult to achieve the object of the present invention.

Moreover, it is better if the following conditions are satisfied.
0.60 <(dy * / dy) _{y * 08} / (dy * / dy) _{y * 00} <0.87 (12-1)

Furthermore, it is best to satisfy the following conditions.
0.70 <(dy * / dy) _{y * 08} / (dy * / dy) _{y * 00} <0.84 (12-2)

Furthermore, the following conditions should be satisfied.
2.55 <(Dw + Dt) / (2 · ΣDt) <4.0 (13)
Where Dw and Dt are distances from the top of the lens surface of the lens unit A closest to the object side to the image plane at the wide-angle end and the telephoto end, respectively, and ΣDt is the second from the top of the lens surface of the lens unit A closest to the object side at the telephoto end. This is the distance to the top of the lens surface closest to the image side of the lens group. When the upper limit is exceeded, the total length at the wide-angle end or the telephoto end becomes long, and the retractable barrel tends to be complicated and enlarged. Below the lower limit, the thickness of the lens increases, and the retractable lens barrel tends to be complicated and enlarged.

Moreover, it is better if the following conditions are satisfied.
2.60 <(Dw + Dt) / (2 · ΣDt) <4.0 (13-1)

Furthermore, it is best to satisfy the following conditions.
2.70 <(Dw + Dt) / (2 · ΣDt) <3.2 (13-2)

Or, even if the following conditions are satisfied, the retractable thickness is good.
0.8 <ΣDt / fw <3.3 (14)
However, ΣDt is the distance from the most object side lens surface top of the lens group A to the most image side lens surface top of the lens group B at the telephoto end. If the upper limit is exceeded, the thickness when retracted is still insufficient. Below the lower limit, it becomes difficult to form a lens component having a predetermined refractive power.

Moreover, it is better if the following conditions are satisfied.
1.2 <ΣDT / fw <2.8 (14-1)

Furthermore, it is best to satisfy the following conditions.
1.5 <ΣDT / fw <2.2 (14-2)

Moreover, it is preferable that the image forming ability of each zoom lens satisfies the following conditions.
1.0 <y * ₁₀ / a <3.0 (15)
However, y * ₁₀ corresponds to the farthest point from the center of the image after distortion correction, the distance from the center to the farthest point in the electronic image sensor, the unit is mm, and a is the long side direction of the electronic image sensor The unit of pixel distance is μm.

Moreover, it is better if the following conditions are satisfied.
1.1 <y * ₁₀ / a <2.5 (15-1)

Furthermore, it is best to satisfy the following conditions.
1.2 <y * ₁₀ / a <2.2 (15-2)

In order to reduce the thickness of the optical low-pass filter as much as possible, the following conditions should be satisfied.
Fw ≧ 1.1a (μm) (16)
Where Fw is the open F value at the wide-angle end, a is the distance between pixels in the long side direction of the electronic image sensor, and the unit is μm.
If this condition is satisfied, aliasing distortion can be tolerated without an optical low-pass filter.

Moreover, it is better if the following conditions are satisfied.
Fw ≧ 1.2a (μm) (16-1)

Furthermore, it is best to satisfy the following conditions.
Fw ≧ 1.3a (μm) (16-2)
This utilizes the fact that when the pixel size is reduced to some extent, the component above the Nyquist frequency disappears due to the influence of diffraction. If the conditions are not satisfied, an optical low-pass filter is necessary. Therefore, in order to ensure image quality, it is better that the aperture stop is only open and not narrowed down. Then, it becomes possible to reduce the size and thickness by the amount that can eliminate the narrowing mechanism.

In the present invention, it is preferable that all the lens groups closer to the image side than the lens group A are composed of only one lens component. For example, the group configuration on the image side of the lens group A is “only one positive group” “two positive and negative groups” “two positive and negative groups” “three positive and positive groups” “positive and positive three groups” Each lens group is composed of one lens component (one lens component has only two lens surfaces in contact with air), that is, one single lens or one cemented lens. By doing so, it is possible to make the depth when retracted extremely thin.
Furthermore, in the present invention, the object of the present invention can be achieved more effectively by simultaneously satisfying two or more of the above-described constituent requirements or conditional expressions.

  In the above, each constituent requirement or conditional expression may be individually limited to the configurations described in claims 1 to 3 or additional items (1) to (22) described later. Furthermore, the same effect is exhibited even if each conditional expression is limited only to the lower limit value or the upper limit value of the limited conditional expression.

Embodiments of the present invention will be described below with reference to the drawings.
First Embodiment FIG. 1 is a sectional view along the optical axis showing the optical configuration of a first embodiment of the zoom lens according to the present invention, where (a) is a wide angle end, (b) is an intermediate end, and (c) is a telephoto end. Each state is shown. FIG. 2 is a diagram showing spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification at the wide-angle end, intermediate point, and telephoto end when the zoom lens shown in FIG. 1 is focused at infinity.

The zoom lens according to the first example includes, in order from the object side, a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power. FL is a plane parallel plate such as an optical low-pass filter or an infrared light absorption filter, CG is a cover glass, and I is an image pickup surface of an image pickup device such as a CCD or CMOS. The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a concave surface facing the image side, and a positive meniscus lens L12 having a convex surface facing the object side with an air gap. The negative meniscus lens L11 has an aspheric surface on the image side.
The second lens group G2 includes, in order from the object side, a cemented lens of a positive first lens L21 having an aspheric surface on the object side surface and a negative second lens L22 having an aspheric surface on the image side surface. The positive first lens L21 is a biconvex positive lens, and the negative second lens L22 is a meniscus lens having a convex surface facing the image side in the vicinity of the optical axis.

  Further, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, the second lens group G2 moves to the object side, the interval decreases, and the first lens group G1 again A zoom system is adopted in which the distance from the second lens group G2 is further reduced by moving toward the object side. That is, the first lens group G1 moves along a locus convex toward the image side, and the second lens group G2 always moves toward the object side. The aperture stop S is provided on the object side surface of the first lens L21 of the second lens group G2, and moves together with the second lens group G2.

Next, numerical data of optical members constituting the zoom lens of the first embodiment are shown. In this data, R is the radius of curvature on the optical axis of each surface of the optical member, D is the spacing between the surfaces, Nd is the refractive index at the d-line of each optical member, Vd is the Abbe number of each optical member, FNO. Represents the F number. The aspheric coefficient is expressed by the following equation when the optical axis direction is z, the direction orthogonal to the optical axis direction is y, the cone coefficient is k, and the aspheric coefficients are A4, A6, A8, A10. The
z = (y ² / R) / [1+ {1- (1 + k) (y / R) ² } ^1/2 ] + A4y ⁴ + A6y ⁶
+ A8y ⁸ + A10y ¹⁰ …
For example, an aspheric coefficient A4 = 8.08242e-04 can be displayed as A4 = 8.08242 × 10 ^−4, but in this data, the aspheric coefficient is displayed in the former expression format.
These symbols and expression formats are also commonly used in numerical data of each embodiment described later.
Numerical data 1
Wide-angle end Medium Telephoto end focal length (mm) 6.226 12.175 17.996
F number 3.31 4.48 6.64
Image height (mm) 4.00 4.00 4.00

Surface number R D Nd Vd
1 250.068 1.00 1.80610 40.92
2 4.556 (Aspherical) 1.33
3 7.527 2.33 2.00069 25.46
4 15.845 D4
5 ∞ (Aperture) -0.53
6 4.395 (Aspherical) 4.00 1.49700 81.61
7 -7.297 1.49 1.68893 31.08
8 -32.808 (Aspherical) D8
9 ∞ 0.50 1.51633 64.14
10 ∞ 0.50
11 ∞ 0.50 1.51633 64.14
12 ∞
13 ∞ (image plane)

Aspheric coefficient surface number R k
2 4.556 -1.136
A4 A6 A8 A10
8.08242e-04 1.04700e-05 -5.12099e-07 1.19042e-08
Surface number R k
6 4.395 -0.225
A4 A6 A8 A10
3.84983e-07 6.98188e-05 -8.04616e-06 5.30603e-07
Surface number R k
8 -32.808 0.000
A4 A6 A8 A10
1.87726e-03 1.60277e-04 -5.65876e-05 1.51576e-06

Zoom data focal length 6.226 12.175 17.996
FNO. 3.31 4.48 6.64
D4 12.62 4.37 1.58
D8 9.00 13.88 18.72

Second Embodiment FIG. 3 is a cross-sectional view along the optical axis showing the optical configuration of a second embodiment of the zoom lens according to the present invention, where (a) is a wide-angle end, (b) is an intermediate end, and (c) is a telephoto end. Each state is shown. FIG. 4 is a diagram showing spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification at the wide-angle end, intermediate point, and telephoto end when the zoom lens shown in FIG. 3 is focused at infinity.

The zoom lens according to the second example 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. FL is a plane parallel plate such as an optical low-pass filter or an infrared light absorption filter, CG is a cover glass, and I is an image pickup surface of an image pickup device such as a CCD or CMOS. The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a concave surface facing the image side, and a positive meniscus lens L12 having a convex surface facing the object side with an air gap. The negative meniscus lens L11 has an aspheric surface on the image side.
The second lens group G2 includes, in order from the object side, a cemented lens of a positive first lens L21 having an aspheric surface on the object side surface and a negative second lens L22 having an aspheric surface on the image side surface. The positive first lens L21 is a biconvex positive lens, and the negative second lens L22 is a meniscus lens having a convex surface facing the image side in the vicinity of the optical axis.

  Further, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, the second lens group G2 moves to the object side, the interval decreases, and the first lens group G1 again A zoom system is adopted in which the distance from the second lens group G2 is further reduced by moving toward the object side. That is, the first lens group G1 moves along a locus convex toward the image side, and the second lens group G2 always moves toward the object side. The aperture stop S is provided on the object side surface of the first lens L21 of the second lens group G2, and moves together with the second lens group G2.

Next, numerical data of optical members constituting the zoom lens of the second embodiment are shown.
Numerical data 2
Wide-angle end Medium Telephoto end focal length (mm) 5.620 9.998 16.279
F number 3.38 4.32 5.69
Image height (mm) 4.00 4.00 4.00

Surface number R D Nd Vd
1 922.031 1.05 1.80610 40.92
2 4.095 (Aspherical surface) 1.17
3 6.921 1.70 2.00069 25.46
4 17.300 D4
5 ∞ (Aperture) -0.50
6 3.828 (Aspherical surface) 3.19 1.49700 81.61
7 -6.086 1.67 1.68893 31.07
8 -50.863 (Aspherical surface) 7.83
9 ∞ 0.76 1.54771 62.84
10 ∞ 0.50
11 ∞ 0.50 1.51633 64.14
12 ∞
13 ∞ (image plane)

Aspheric coefficient surface number R k
2 4.095 -1.024
A4 A6 A8 A10
8.79240e-04 1.70698e-06 2.25859e-09 1.19042e-08
Surface number R k
6 3.828 -0.033
A4 A6 A8 A10
-8.00844e-05 2.50122e-06 6.74718e-06 -7.28132e-07
Surface number R k
8 -50.863 0.000
A4 A6 A8 A10
3.04106e-03 3.34496e-04 -2.45110e-05 8.04457e-06

Zoom data focal length 5.620 9.998 16.279
FNO. 3.38 4.32 5.69
D4 12.68 5.20 1.50

Third Embodiment FIG. 5 is a cross-sectional view along the optical axis showing the optical configuration of a third embodiment of the zoom lens according to the present invention, where (a) is the wide-angle end, (b) is the middle, and (c) is the telephoto end. Each state is shown. FIG. 6 is a diagram showing spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification at the wide-angle end, intermediate point, and telephoto end when the zoom lens shown in FIG. 5 is focused at infinity.

The zoom lens according to the third example includes, in order from the object side, a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power. FL is a plane parallel plate such as an optical low-pass filter or an infrared light absorption filter, CG is a cover glass, and I is an image pickup surface of an image pickup device such as a CCD or CMOS. The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a concave surface facing the image side, and a positive meniscus lens L12 having a convex surface facing the object side with an air gap. The negative meniscus lens L11 has an aspheric surface on the image side.
The second lens group G2 includes, in order from the object side, a cemented lens of a positive first lens L21 having an aspheric surface on the object side surface and a negative second lens L22 having an aspheric surface on the image side surface. The positive first lens L21 is a biconvex positive lens, and the negative second lens L22 is a meniscus lens having a convex surface facing the image side in the vicinity of the optical axis.

  Further, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, the second lens group G2 moves to the object side, the interval decreases, and the first lens group G1 again A zoom system is adopted in which the distance from the second lens group G2 is further reduced by moving toward the object side. That is, the first lens group G1 moves along a locus convex toward the image side, and the second lens group G2 always moves toward the object side. The aperture stop S is provided on the object side surface of the first lens L21 of the second lens group G2, and moves together with the second lens group G2.

Next, numerical data of optical members constituting the zoom lens of the third example are shown.
Numerical data 3
Wide-angle end Medium Telephoto end focal length (mm) 5.909 11.818 17.110
F number 3.35 4.57 5.67
Image height (mm) 4.00 4.00 4.00

Surface number R D Nd Vd
1 67.974 1.00 1.74320 49.34
2 4.359 (Aspherical surface) 1.59
3 6.938 1.83 2.00330 28.27
4 11.039 D4
5 ∞ (Aperture) -0.50
6 4.141 (Aspherical) 3.59 1.49700 81.61
7 -7.008 1.53 1.68893 31.08
8 -35.323 (Aspherical) D8
9 ∞ 0.50 1.51633 64.14
10 ∞ 0.50
11 ∞ 0.50 1.51633 64.14
12 ∞
13 ∞ (image plane)

Aspheric coefficient surface number R k
2 4.369 -0.835
A4 A6 A8
6.72372e-04 -8.32895e-06 1.03527e-07
Surface number R k
6 4.141 -0.825
A4 A6 A8 A10
1.18328e-03 1.04436e-04 -8.41120e-06 8.39173e-07
Surface number R k
8 -35.323 0.000
A4 A6 A8 A10
2.25904e-03 2.54243e-04 -2.28439e-05 4.60983e-06

Zoom data focal length 5.909 11.818 17.110
FNO. 3.35 4.57 5.67
D4 12.46 4.10 1.51
D8 8.40 13.10 17.38

Fourth Embodiment FIG. 7 is a cross-sectional view along the optical axis showing the optical configuration of a fourth embodiment of the zoom lens according to the present invention, where (a) is the wide-angle end, (b) is the middle, and (c) is the telephoto end. Each state is shown. FIG. 8 is a diagram showing spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification at the wide-angle end, intermediate point, and telephoto end when the zoom lens shown in FIG. 7 is focused at infinity.

The zoom lens according to the fourth example 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. FL is a plane parallel plate such as an optical low-pass filter or an infrared light absorption filter, CG is a cover glass, and I is an image pickup surface of an image pickup device such as a CCD or CMOS. The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a concave surface facing the image side, and a positive meniscus lens L12 having a convex surface facing the object side with an air gap. The negative meniscus lens L11 has an aspheric surface on the image side.
The second lens group G2 includes, in order from the object side, a cemented lens of a positive first lens L21 having an aspheric surface on the object side surface and a negative second lens L22 having an aspheric surface on the image side surface. The positive first lens L21 is a biconvex positive lens, and the negative second lens L22 is a meniscus lens having a convex surface facing the image side in the vicinity of the optical axis.

  Further, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, the second lens group G2 moves to the object side, the interval decreases, and the first lens group G1 again A zoom system is adopted in which the distance from the second lens group G2 is further reduced by moving toward the object side. That is, the first lens group G1 moves along a locus convex toward the image side, and the second lens group G2 always moves toward the object side. The aperture stop S is provided on the object side surface of the first lens L21 of the second lens group G2, and moves together with the second lens group G2.

Next, numerical data of optical members constituting the zoom lens of the fourth example are shown.
Numerical data 4
Wide-angle end Medium Telephoto end focal length (mm) 5.358 10.585 15.669
F number 3.33 4.53 5.70
Image height (mm) 4.00 4.00 4.00

Surface number R D Nd Vd
1 42.910 1.05 1.74320 49.34
2 3.901 (Aspherical surface) 1.80
3 6.598 1.74 2.00330 28.27
4 10.102 D4
5 ∞ (Aperture) -0.50
6 4.005 (Aspherical) 4.00 1.49700 81.61
7 -6.224 1.20 1.68893 31.07
8 -26.605 (Aspherical surface) 7.78
9 ∞ 0.76 1.57441 62.84
10 ∞ 0.50
12 ∞ 0.50 1.51633 64.14
13 ∞ (image plane)

Aspheric coefficient surface number R k
2 3.901 -0.868
A4 A6 A8
9.04885e-04 1.06270e-05 2.60847e-07
Surface number R k
6 4.005 -0.136
A4 A6 A8 A10
-6.47187e-05 -4.94017e-07 5.38159e-06 -5.22063e-07
Surface number R k
8 -26.605 0.000
A4 A6 A8 A10
2.69143e-03 1.32771e-04 -2.74676e-05 -8.19770e-07

Zoom data focal length 5.358 10.585 15.669
FNO. 3.33 4.53 5.70
D4 11.78 4.07 1.50

Fifth Embodiment FIG. 9 is a sectional view along the optical axis showing the optical configuration of the third embodiment of the zoom lens according to the present invention, where (a) is the wide-angle end, (b) is the middle, and (c) is the telephoto end. Each state is shown. FIG. 10 is a diagram showing spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification at the wide-angle end, intermediate point, and telephoto end when the zoom lens shown in FIG. 9 is focused at infinity.

The zoom lens of the fifth example 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. FL is a plane parallel plate such as an optical low-pass filter or an infrared light absorption filter, CG is a cover glass, and I is an image pickup surface of an image pickup device such as a CCD or CMOS. The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a concave surface facing the image side, and a positive meniscus lens L12 having a convex surface facing the object side with an air gap. The negative meniscus lens L11 has an aspheric surface on the image side.
The second lens group G2 includes, in order from the object side, a cemented lens of a positive first lens L21 having an aspheric surface on the object side surface and a negative second lens L22 having an aspheric surface on the image side surface. The positive first lens L21 is a biconvex positive lens, and the negative second lens L22 is a meniscus lens having a convex surface facing the image side in the vicinity of the optical axis.

  Further, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, the second lens group G2 moves to the object side, the interval decreases, and the first lens group G1 again A zoom system is adopted in which the distance from the second lens group G2 is further reduced by moving toward the object side. That is, the first lens group G1 moves along a locus convex toward the image side, and the second lens group G2 always moves toward the object side. The aperture stop S is provided on the object side surface of the first lens L21 of the second lens group G2, and moves together with the second lens group G2.

Next, numerical data of optical members constituting the zoom lens of the fifth example are shown.
Numerical data 5
Wide-angle end Medium Telephoto end focal length (mm) 5.885 11.521 17.041
F number 3.30 4.48 5.65
Image height (mm) 3.79 3.79 3.79

Surface number R D Nd Vd
1 280.308 1.16 1.80610 40.92
2 4.306 (Aspherical) 1.27
3 7.232 2.09 2.00069 25.46
4 15.661 D4
5 ∞ (Aperture) -0.50
6 4.129 (Aspherical surface) 3.80 1.49700 81.61
7 -6.751 1.44 1.68893 31.08
8 -33.079 (Aspherical) D8
9 ∞ 0.50 1.51633 64.14
10 ∞ 0.50
11 ∞ 0.50 1.51633 64.14
12 ∞
13 ∞ (image plane)

Aspheric coefficient surface number R k
2 4.306 -1.148
A4 A6 A8 A10
9.34434e-04 1.43105e-05 -9.06925e-07 2.34642e-08
Surface number R k
6 4.129 -0.227
A4 A6 A8 A10
-1.66242e-05 9.99900e-05 -1.35791e-05 1.00549e-06
Surface number R k
8 -33.079 0.000
A4 A6 A8 A10
2.25782e-03 2.26033e-04 -1.07638e-05 2.82873e-06

Zoom data focal length 5.885 11.521 17.041
FNO. 3.30 4.48 5.65
D4 12.05 4.17 1.50
D8 8.39 13.02 17.60

Sixth Embodiment FIG. 11 is a cross-sectional view along the optical axis showing the optical configuration of a sixth embodiment of the zoom lens according to the present invention, where (a) is the wide-angle end, (b) is the middle, and (c) is the telephoto end. Each state is shown. FIG. 12 is a diagram showing spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification at the wide-angle end, intermediate point, and telephoto end when the zoom lens shown in FIG. 11 is focused at infinity.

The zoom lens according to the sixth example 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. FL is a plane parallel plate such as an optical low-pass filter or an infrared light absorption filter, CG is a cover glass, and I is an image pickup surface of an image pickup device such as a CCD or CMOS. The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a concave surface facing the image side, and a positive meniscus lens L12 having a convex surface facing the object side with an air gap. The negative meniscus lens L11 has an aspheric surface on the image side.
The second lens group G2 includes, in order from the object side, a cemented lens of a positive first lens L21 having an aspheric surface on the object side surface and a negative second lens L22 having an aspheric surface on the image side surface. The positive first lens L21 is a biconvex positive lens, and the negative second lens L22 is a meniscus lens having a convex surface facing the image side in the vicinity of the optical axis.

  Further, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, the second lens group G2 moves to the object side, the interval decreases, and the first lens group G1 again A zoom system is adopted in which the distance from the second lens group G2 is further reduced by moving toward the object side. That is, the first lens group G1 moves along a locus convex toward the image side, and the second lens group G2 always moves toward the object side. The aperture stop S is provided on the object side surface of the first lens L21 of the second lens group G2, and moves together with the second lens group G2.

Next, numerical data of optical members constituting the zoom lens of the sixth example are shown.
Numerical data 6
Wide-angle end Medium Telephoto end focal length (mm) 5.910 11.870 17.268
F number 3.26 4.53 5.68
Image height (mm) 4.00 4.00 4.00

Surface number R D Nd Vd
1 289.049 1.24 1.74320 49.34
2 4.272 (Aspherical) 1.35
3 6.530 1.67 2.00330 28.27
4 10.551 D4
5 ∞ (Aperture) -0.50
6 4.042 (Aspherical) 3.55 1.49700 81.61
7 -6.969 1.11 1.58393 30.21
8 -75.231 (Aspherical) 8.36
9 ∞ 0.76 1.54771 62.84
10 ∞ 0.50
11 ∞ 0.50 1.51633 64.14
12 ∞
13 ∞ (image plane)

Aspheric coefficient surface number R k
2 4.272 -0.801
A4 A6 A8 A10
7.68306e-04 -8.82529e-06 2.19613e-06 -6.85302e-08
Surface number R k
6 4.042 0.047
A4 A6 A8 A10 A12
-5.30379e-04 2.18540e-04 -7.99714e-05 1.27635e-05 -7.63108e-07
Surface number R k
8 -76.231 0.000
A4 A6 A8 A10 A12
3.00085e-03 4.82212e-04 -1.36755e-04 3.92413e-05 -3.28147e-06

Zoom data focal length 5.910 11.870 17.268
FNO. 3.26 4.53 5.68
D4 11.08 3.78 1.51

《注1》歪曲収差補正前における計算値である。
《注2》各実施例ともに広角端近傍では歪曲収差を画像処理にて補正することを前提としているため、補正後の半画角を掲載している。なお、補正の際にはｙ*10×0.6対応の半画角が補正前後でほぼ不変となるようにしている。 Next, the values of the conditional expressions in each example are shown in the following table.

<< Note 1 >> Calculated values before distortion correction.
<< Note 2 >> Since each embodiment assumes that distortion is corrected by image processing near the wide-angle end, the corrected half angle of view is shown. In the correction, the half angle of view corresponding to y * 10 × 0.6 is substantially unchanged before and after the correction.

  The zoom lens of the present invention as described above forms an object image, and the image is received by an image pickup device such as a CCD, and can be used for a photographing apparatus, particularly a digital camera or a video camera. The embodiment is illustrated below.

  FIG. 13 to FIG. 15 are conceptual diagrams of structures in which the zoom optical system according to the present invention is incorporated in the photographing optical system 41 of a digital camera. 13 is a front perspective view showing the external appearance of the digital camera 40, FIG. 14 is a rear front view thereof, and FIG. 15 is a schematic perspective plan view showing the configuration of the digital camera 40. However, FIGS. 13 and 15 show a state in which the photographing optical system 41 is not retracted. In this example, the digital camera 40 includes a photographing optical system 41 having a photographing optical path 42, a finder optical system 43 having a finder optical path 44, a shutter button 45, a flash 46, a liquid crystal display monitor 47, a focal length change button 61, When the photographing optical system 41 is retracted, including the setting change switch 62, the photographing optical system 41, the finder optical system 43, and the flash 46 are covered with the cover 60 by sliding the cover 60. Then, when the cover 60 is opened and the camera 40 is set to the photographing state, the photographing optical system 41 enters the non-collapsed state of FIG. 15, and when the shutter button 45 disposed on the upper side of the camera 40 is pressed, the photographing is performed in conjunction therewith. Photographing is performed through the optical system 41, for example, the zoom lens of the first embodiment. An object image formed by the photographing optical system 41 is formed on the imaging surface of the CCD 49 via a low-pass filter LF having an IR cut coat and a cover glass CG. The object image received by the CCD 49 is displayed as an electronic image on the liquid crystal display monitor 47 provided on the back of the camera via the processing means 51. Further, the processing means 51 is connected to a recording means 52 so that a photographed electronic image can be recorded. The recording unit 52 may be provided separately from the processing unit 51, or may be configured to perform recording and writing electronically using a floppy (registered trademark) disk, a memory card, an MO, or the like. Further, it may be configured as a silver salt camera in which a silver salt film is arranged in place of the CCD 49.

Further, a finder objective optical system 53 is disposed on the finder optical path 44. The finder objective optical system 53 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 41. The object image formed by the finder objective optical system 53 is formed on the field frame 57 of the erecting prism 55 that is an image erecting member. Behind the erecting prism 55, an eyepiece optical system 59 for guiding the erect image to the observer eyeball E is disposed. A cover member 50 is disposed on the exit side of the eyepiece optical system 59.
The digital camera 40 configured as described above can achieve high performance and downsizing since the photographing optical system 41 has high performance and is small and can be retracted.

FIG. 16 is a block diagram showing the internal circuitry of the main part of the digital camera 40. In the following description, the processing unit 51 includes, for example, the CDS / ADC unit 24, the temporary storage memory 17, the image processing unit 18, and the like, and the recording unit 52 includes, for example, the storage medium unit 19 and the like.
As shown in FIG. 16, the digital camera 40 includes an operation unit 12, a control unit 13 connected to the operation unit 12, and an imaging drive circuit connected to control signal output ports of the control unit 13 via buses 14 and 15. 16, a temporary storage memory 17, an image processing unit 18, a storage medium unit 19, a display unit 20, and a setting information storage memory unit 21.

  The temporary storage memory 17, the image processing unit 18, the storage medium unit 19, the display unit 20, and the setting information storage memory unit 21 are configured to be able to input or output data with each other via the bus 22 The imaging drive circuit 16 is connected with a CCD 49 and a CDS / ADC unit 24.

  The operation unit 12 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 13 is a central processing unit composed of, for example, a CPU, and has a built-in program memory (not shown). The control unit 13 is input by a camera user via the operation unit 12 according to a program stored in the program memory. This circuit controls the entire digital camera 40 in response to the instruction command.

  The CCD 49 receives the object image formed through the photographing optical system 41 incorporating the zoom optical system of the present invention. The CCD 49 is an image pickup element that is driven and controlled by the image pickup drive circuit 16 and converts the light amount of each pixel of the object image into an electric signal and outputs the electric signal to the CDS / ADC unit 24.

  The CDS / ADC unit 24 amplifies the electrical signal input from the CCD 49 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. It is a circuit that outputs to the memory 17.

  The temporary storage memory 17 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 24. The image processing unit 18 reads out the RAW data stored in the temporary storage memory 17 or the RAW data stored in the storage medium unit 19, and performs various corrections including distortion correction based on the image quality parameter designated by the control unit 13. It is a circuit that performs image processing electrically.

  The recording medium unit 19 detachably mounts a card-type or stick-type recording medium made of, for example, a flash memory, and the RAW data transferred from the temporary storage memory 17 to the card-type or stick-type flash memory. It is a control circuit of an apparatus that records and holds image data processed by the image processing unit 18.

  The display unit 20 includes a liquid crystal display monitor 47 and is a circuit that displays an image, an operation menu, and the like on the liquid crystal display monitor 47. The setting information storage memory unit 21 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 12 among the image quality parameters read from the ROM unit. RAM section is provided. The setting information storage memory unit 21 is a circuit for controlling input / output to / from these memories.

As described above, the zoom lens of the present invention and the electronic image pickup apparatus having the same have the following features.
(1) In order from the object side, a lens group A composed of two lens components having negative refractive power and a negative lens component and a positive lens component, and a plurality of lens elements having positive refractive power are joined. In a zoom lens that includes a lens group B composed of one lens component, and the relative distance between the lens groups changes upon zooming or focusing, the negative lens component of the lens group A is such that the image-side surface is away from the optical axis. A zoom lens comprising an aspheric surface whose divergence increases as the distance from the lens increases. However, the lens component is a lens component in which only the lens surface on the most object side and the lens surface on the most image side of the lens component are in contact with air and there is no air gap between them. Unit.

(2) In order from the object side, a lens group A composed of two lens components having negative refractive power and a negative lens component and a positive lens component, and a plurality of lens elements having positive refractive power are joined. In a zoom lens that includes a lens group B composed of one positive lens component, and the relative spacing of each lens group changes upon zooming or focusing, an aspherical surface among all the optical refractive surfaces constituting the lens group A A zoom lens, wherein the number of surfaces is 50% or less. However, the lens component is a lens component in which only the lens surface on the most object side and the lens surface on the most image side of the lens component are in contact with air and there is no air gap between them. Unit.

(3) In order from the object side, a plurality of lens elements having a positive refractive power and a lens group A composed of two lens components having a negative refractive power and a negative lens component and a positive lens component are joined. In a zoom lens that includes a lens group B composed of one positive lens component, and the relative distance between the lens groups changes upon zooming or focusing, the positive lens component of the lens group A is a medium having a refractive index of 1.87 or more. Zoom lens including positive lens consisting of However, the lens component is a lens component in which only the lens surface on the most object side and the lens surface on the most image side of the lens component are in contact with air and there is no air gap between them. Unit.

(4) In order from the object side, a plurality of lens elements having a positive refractive power and a lens group A including two lens components having a negative refractive power and a negative lens component and a positive lens component are joined. A zoom lens that includes a lens group B composed of one positive lens component, and in which the relative distance between the lens groups changes upon zooming or focusing, and satisfies the following conditions.
0.8 <ΣT / fw <2.5
Where ΣT is the sum of the distances on the optical axis from the most object-side surface to the most image-side surface of all lens groups, and fw is the focal length of the entire system at the wide-angle end. In the lens component, only the lens surface on the most object side and the lens surface on the most image side of the lens component are in contact with air and there is no air space between them, and a single lens or a cemented lens is taken as one unit.

(5) In order from the object side, a lens group A composed of two lens components having negative refractive power and a negative lens component and a positive lens component, and a plurality of lens elements having positive refractive power are joined. A zoom lens that includes a lens group B composed of one positive lens component, and in which the relative distance between the lens groups changes upon zooming or focusing, and satisfies the following conditions.
0.4 <fR / | fA | <1.2
Here, fA is the focal length of the lens group A, and fR is the combined focal length at the wide angle end of all the lens groups arranged on the image side of the lens group A.

(6) In order from the object side, a lens group A composed of two lens components having negative refractive power and a negative lens component and a positive lens component, and a plurality of lens elements having positive refractive power are joined. A zoom lens that includes a lens group B composed of one positive lens component, and in which the relative distance between the lens groups changes upon zooming or focusing, and satisfies the following conditions.
1.20 <| βRT | <2.30
However, βRT is a combined magnification of all the lens units arranged on the image side of the lens unit A when the telephoto end infinity object point is focused.

(7) In order from the object side, a lens group A composed of two lens components having a negative refractive power and a negative lens component and a positive lens component, and a plurality of lens elements having a positive refractive power are joined. A zoom lens that includes a lens group B composed of one positive lens component, and in which the relative distance between the lens groups changes upon zooming or focusing, and satisfies the following conditions.
0.17 <(D12W−D12T) / (fw · γ ² ) <0.45
However, D12W and D12T are the air intervals on the optical axis between the lens group A at the wide-angle end and the telephoto end and the lens group adjacent to the image side. γ is the ratio of the focal length of the entire system at the telephoto end when focusing on an object point at infinity to the wide-angle end, and fw is the focal length of the entire system at the wide-angle end.

(8) In order from the object side, a plurality of lens elements having a positive refractive power and a lens unit A including two lens components having a negative refractive power and a negative lens component and a positive lens component are joined. A zoom lens that includes a lens group B composed of one positive lens component, and in which the relative distance between the lens groups changes upon zooming or focusing, and satisfies the following conditions.
0.06 <d11 / fw <0.53
Here, fw is the focal length of the entire system at the wide-angle end, and d11 is the air space on the optical axis between the negative lens component and the positive lens component of the lens group A.

(9) In order from the object side, a lens group A composed of two lens components having negative refractive power and a negative lens component and a positive lens component, and a plurality of lens elements having positive refractive power are joined. In a zoom lens including a lens group B composed of one positive lens component, and the relative interval of each lens group changes during zooming or focusing, the lens group A includes a positive lens and a negative lens on the object side. Any of the above (1) to (8) satisfying the following conditions when the refractive index and Abbe number of the medium constituting each of the positive lens and the negative lens are n1p, ν1p, n1n, ν1n Zoom lens described in 1.
0.08 <n1p-n1n <0.35
5 <ν1n−ν1p <25

(10) In order from the object side, a lens group A including two lens components having a negative refractive power and a negative lens component and a positive lens component, and a plurality of lens elements having a positive refractive power are joined. A zoom lens that includes a lens group B composed of one positive lens component, and in which the relative distance between the lens groups changes upon zooming or focusing, and satisfies the following conditions.
0.66 <(R23 + R21) / (R23−R21) <1.5
R21 and R23 are radii of curvature on the optical axis of the most object-side surface and the most image-side surface of the lens group B, respectively.

(11) In order from the object side, a lens group A composed of two lens components having a negative refractive power and a negative lens component and a positive lens component, and a plurality of lens elements having a positive refractive power are joined. A zoom lens that includes a lens group B composed of one positive lens component, and in which the relative distance between the lens groups changes upon zooming or focusing, and satisfies the following conditions.
ν2p> 65
Here, ν2p is the Abbe number (d-line reference) of the medium constituting the positive lens included in the lens group B.

(12) In order from the object side, a lens group A composed of two lens components having negative refractive power and a negative lens component and a positive lens component, and a plurality of lens elements having positive refractive power are joined. In a zoom lens that includes a lens group B composed of one positive lens component, and the relative spacing of each lens group changes during zooming or focusing, the lens group B is composed of a cemented lens of a positive lens and a negative lens, A zoom lens that satisfies the following conditions.
−1.5 <fw / R22 <−0.50
Here, R22 is the radius of curvature of the cemented surface of the lens group B on the optical axis.

 (13) The zoom lens according to any one of (1) to (12), wherein the lens group B includes a cemented lens of a positive lens and a negative lens.

(14) The zoom lens according to any one of (1) to (13), including only the lens group A and the lens group B.

(15) The zoom lens according to (14), which satisfies the following condition.
2.55 <(Dw + Dt) / (2 · ΣDt) <4.0
Where Dw and Dt are the distance from the top of the lens surface of the lens unit A closest to the image surface to the image plane at the wide-angle end and the telephoto end, respectively, and ΣDt is the lens unit from the top of the lens surface of the lens unit A at the telephoto end of the lens unit B is the distance to the top of the lens surface closest to the image side.

(16) The zoom lens according to any one of (13) to (15), which satisfies the following condition.
0.8 <ΣDt / fw <3.3
However, ΣDt is the distance from the most object side lens surface top of the lens group A to the most image side lens surface top of the lens group B at the telephoto end.

(17) An electronic image pickup apparatus comprising: the zoom lens according to any one of (1) to (16) above; and an electronic image pickup element arranged on the image side of the zoom lens.

(18) In order from the object side, a lens group A composed of two lens components having negative refractive power and a negative lens component and a positive lens component, and a plurality of lens elements having positive refractive power are joined. A zoom lens including a lens group B composed of one positive lens component, the relative interval of each lens group changing at the time of zooming or focusing, an electronic image sensor disposed on the image side of the zoom lens, and the zoom An electronic imaging apparatus including an image processing unit capable of processing image data obtained by imaging an image formed through a lens by the electronic imaging element and outputting the processed image data as image data having a changed shape. However, the lens component is a lens component in which only the lens surface on the most object side and the lens surface on the most image side of the lens component are in contact with air and there is no air gap between them. Unit.

(19) The electronic imaging apparatus according to (18), wherein the following condition is satisfied when the zoom lens is focused on any object distance equal to or greater than 50 times fw.
0.75 <y * ₀₈ / (fw · tan _ω08w ) <0.96
However, y * ₁₀ corresponds to the point farthest from the center of the image after distortion correction, and if the distance from the center to the farthest point in the electronic image sensor is y * ₁₀ , y * ₀₈ = 0.8y * ₁₀ , Ω _08w is an angle formed by a light beam corresponding to an image point connected to a position y * ₀₈ away from the center on the imaging surface at the wide-angle end and an optical axis in the object direction, and fw is a focal length of the entire system at the wide-angle end. It is.

(20) The electronic imaging apparatus according to (18) or (19), wherein the following condition is satisfied when the zoom lens is focused on any object distance equal to or greater than 50 times fw.
0.50 <(dy * / dy) y * ₀₈ / (dy * / dy) y * ₀₀ <0.90
However, (dy * / dy) y * ₀₈ represents the differential amount dy * / dy at y * ₀₈ , and (dy * / dy) y * ₀₀ represents the differential amount dy * / dy at the paraxial axis.

(21) The electronic imaging device according to any one of (18) to (20), which satisfies the following condition.
1.0 <y * ₁₀ / a <3.0
However, y * ₁₀ is the distance from the point farthest from the center of the image after distortion correction to the point farthest from the center of the electronic image sensor, the unit is mm, and a is a pixel in the long side direction of the electronic image sensor The unit of distance is μm.

(22) The zoom lens according to any one of (16) to (21), which satisfies the following condition.
Fw ≧ 1.1a (μm)
Where Fw is the open F value at the wide-angle end, a is the distance between the pixels in the long side direction of the electronic image sensor, and the unit is μm.

1 is a cross-sectional view along the optical axis showing the lens configuration of a first embodiment of a zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. The spherical aberration, the curvature of field, the distortion aberration, and the chromatic aberration of magnification in the first example are shown, (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. FIG. 5 is a cross-sectional view along the optical axis showing the lens configuration of a second embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. Spherical aberration, field curvature, distortion, and lateral chromatic aberration in the second example are shown, (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. FIG. 6 is a cross-sectional view along the optical axis showing the lens configuration of a third embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. The spherical aberration, field curvature, distortion, and lateral chromatic aberration in the third example are shown, (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. FIG. 6 is a cross-sectional view along the optical axis showing the lens configuration of a fourth embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. The spherical aberration, field curvature, distortion, and lateral chromatic aberration in the fourth example are shown, (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. FIG. 7 is a cross-sectional view along the optical axis showing the lens configuration of a fifth embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. Spherical aberration, curvature of field, distortion, and lateral chromatic aberration in the fifth example are shown, (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. FIG. 6 is a cross-sectional view along the optical axis showing the lens configuration of a sixth embodiment of the zoom lens according to the present invention, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the telephoto end. The spherical aberration, field curvature, distortion, and lateral chromatic aberration in the sixth example are shown, (a) shows the wide-angle end, (b) the middle, and (c) the telephoto end. It is a front perspective view which shows an example of the external appearance of the retractable digital camera incorporating the zoom optical system by this invention. FIG. 14 is a rear front view of the digital camera shown in FIG. 13. FIG. 14 is a schematic perspective plan view showing the configuration of the digital camera shown in FIG. 13. FIG. 14 is a configuration block diagram of an internal circuit of a main part of the digital camera shown in FIG. 13.

Explanation of symbols

G1 first lens group
G2 second lens group
S Aperture
LPF optical low-pass filter
CG cover glass
I Imaging surface of the electronic image sensor
L11, L12 The first and second lenses of the first lens group
L22, L22 First lens and second lens of second lens group 12 Operation unit 13 Control unit 14, 15, 22 Bus 16 Imaging drive circuit 17 Temporary storage memory 18 Image processing unit 19 Storage medium unit 20 Display unit 21 Setting information storage Memory unit 24 CDS / ADC unit 40 Digital camera 41 Imaging optical system 42 Optical path for imaging 43 Monitor 44 Optical path for viewfinder 45 Shutter button 45 Flash 47 LCD monitor 49 CCD
51 processing means 50 cover member 52 recording means 53 finder objective optical system 55 erecting prism 57 field frame 59 eyepiece optical system 60 cover 61 focal length change button

Claims (3)

  In order from the object side, a lens group A composed of two lens components having a negative refractive power and a negative lens component and a positive lens component, and a single lens in which a plurality of lens elements having a positive refractive power are joined. In a zoom lens that includes a lens group B composed of components, and the relative distance between the lens groups changes during zooming or focusing, the negative lens component of the lens group A diverges as the image-side surface moves away from the optical axis. A zoom lens characterized by comprising an aspheric surface with enhanced action. However, the lens component is a lens component in which only the lens surface on the most object side and the lens surface on the most image side of the lens component are in contact with air and there is no air gap between them. Unit.   In order from the object side, a lens group A composed of two lens components having a negative refractive power and a negative lens component and a positive lens component, and one positive lens in which a plurality of lens elements having a positive refractive power are joined. In a zoom lens that includes a lens group B composed of lens components, and the relative distance between the lens groups changes upon zooming or focusing, a surface that is an aspherical surface among all the optical refractive surfaces that constitute the lens group A A zoom lens characterized in that the number is 50% or less. However, the lens component is a lens component in which only the lens surface on the most object side and the lens surface on the most image side of the lens component are in contact with air and there is no air gap between them. Unit.   In order from the object side, a lens group A composed of two lens components having a negative refractive power and a negative lens component and a positive lens component, and one positive lens in which a plurality of lens elements having a positive refractive power are joined. In a zoom lens that includes a lens group B composed of lens components, and the relative distance between the lens groups changes upon zooming or focusing, the positive lens component of the lens group A is a positive lens made of a medium having a refractive index of 1.87 or more. Zoom lens including lens. However, the lens component is a lens component in which only the lens surface on the most object side and the lens surface on the most image side of the lens component are in contact with air and there is no air gap between them. Unit.

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