JP2009098200A - Three-unit zoom lens and imaging device with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-unit zoom lens which is advantageous in making the zoom lens small in size and have high performance, and capable of easily suppressing an influence on decentering between lenses. <P>SOLUTION: The zoom lens includes, in order from an object side: a negative first lens unit G1; a positive second lens unit G2, and a third lens group G3; wherein during zooming from the wide angle end to the telephoto end, a distance between the first lens unit G1 and the second lens unit G2 decreases and a distance between the second lens unit G2 and the third lens unit G3 changes. The first lens unit G2 is composed of one negative lens component including, in order from the object side, a negative lens having a concave surface directed toward the image side and a positive lens having a convex surface directed toward the object side. The second lens unit G2 includes at least one negative lens and a plurality of positive lenses, wherein at least three lenses among these lenses are cemented to adjacent lenses, the total number of lens components included in the second lens unit G2 is two or less. The third lens unit G3 is composed of one lens component composed of two or less lenses. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a small zoom lens and an imaging apparatus such as a compact digital camera using the same.

  Conventionally, digital cameras and video cameras have been required to have high image quality, high zoom ratio, and thin mirror frame.

  For example, Japanese Patent Application Laid-Open No. 2005-308953 discloses a three-group zoom lens including a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group. In this three-group zoom lens, the first lens group is composed of a cemented lens component of a biconcave negative lens and a positive lens in order from the object side, the second lens group is composed of two lenses, and the third lens group is composed of one sheet. It consists of a lens. Therefore, it is excellent in terms of downsizing.

JP 2005-308953 A

  However, this zoom lens has a small number of lenses in order to correct aberrations in the second lens group. Therefore, it is difficult to achieve a high zoom ratio while suppressing various aberrations such as chromatic aberration.

  SUMMARY OF THE INVENTION In view of such problems, the present invention has an object to provide a three-group zoom lens that is advantageous for downsizing and high performance, and that can easily suppress the influence of decentering between lenses, and an imaging apparatus including the same. is there.

In order to solve the above-described problems and achieve the object, the three-group zoom lens of the present invention includes:
From the object side,
A first lens group having negative refractive power,
A second lens group having positive refractive power,
A third lens group having refractive power,
A three-group zoom lens in which the distance between the first lens group and the second lens group is narrowed and the distance between the second lens group and the third lens group is changed upon zooming from the wide-angle end to the telephoto end is a basic configuration. Yes.

Thus, by making the lens unit having a negative refractive power the lens unit closest to the object side, it is advantageous for reducing the diameter of the lens and securing the angle of view at the wide angle end.
Then, zooming is performed by changing the distance between the first lens group having negative refractive power and the second lens group having positive refractive power. Then, the arrangement of the third lens group having a refractive power is advantageous for adjusting the exit pupil position and the like.

  In such a three-group zoom lens, by configuring each lens group as follows, it becomes easy to reduce the size, secure the optical performance, and reduce the influence on the eccentricity.

  When the lens component has only two lens bodies on the optical axis that are in contact with air, the object side surface and the image side surface, the first lens group includes a negative lens with a concave surface directed from the object side to the image side and the object side. And a lens component having a negative refracting power and having a positive lens with a convex surface facing the surface.

As described above, the first lens group is configured by one negative lens component, so that the thickness of the first lens group can be easily reduced. The negative lens component having a negative lens having a concave surface facing the image side and a positive lens is advantageous in reducing spherical aberration and chromatic aberration generated in the first lens group. The relative decentration between the lenses can be easily suppressed, and the influence on the off-axis aberration due to the decentration can be reduced.
The second lens group includes at least one negative lens and a plurality of positive lenses, and at least three of the lenses are joined to the adjacent lens, and the lens components included in the second lens group The total number is 2 or less.

By configuring in this way, the positive refractive power of the second lens group is shared by a plurality of positive lenses, and a negative lens is provided in the second lens group, which is advantageous for correction of spherical aberration and chromatic aberration.
In addition, at least three lenses are joined to the adjacent lens, and the second lens group is composed of two or less lens components, so that it is easy to secure the chromatic aberration correction function and to suppress the influence on the aberration due to the relative decentration of the lenses. Become.

The third lens group is composed of one lens component composed of two or less lenses. In order to give the second lens group a zooming function, it is preferable that the third lens group has a simple configuration advantageous for thinning as described above.
And, it is advantageous for reducing the thickness when the lens barrel is retracted by comprising four lens components as a whole.

  Furthermore, it is more preferable to satisfy any of the following configurations. The negative lens component in the first lens group preferably has an aspherical cemented surface. By making the cemented surface in the first lens group an aspherical surface, it is possible to mainly correct lateral chromatic aberration favorably.

  The negative lens component in the first lens group may have a spherical cemented surface. By making the cemented surface in the first lens group spherical, it can be manufactured at low cost.

Further, it is preferable that the first lens group satisfies the following conditions.
0.05 <D _G1 / f _w <0.8 (1)
However,
D _G1 is the thickness of the first lens unit on the optical axis,
f _w is the focal length at the wide-angle end of the three-group zoom lens,
It is.

Conditional expression (1) relates to a preferred thickness on the optical axis of the first lens group.
By making it not fall below the lower limit of conditional expression (1), it becomes easy to secure the refractive power of the positive lens, and it becomes easy to obtain good optical performance.
By making sure that the upper limit of conditional expression (1) is not exceeded, it is advantageous for reducing the thickness when retracted.

Further, it is preferable that the lens component closest to the object side in the second lens group is a cemented lens component that satisfies the following conditions.
0.5 <f _G2C1 / f _w <5.0 (2)
However,
f _G2C1 is the focal length of the most object-side lens component in the second lens group,
f _w is the focal length at the wide-angle end of the three-group zoom lens,
It is.

Conditional expression (2) relates to the refractive power of the second lens group.
By making sure that the lower limit of conditional expression (2) is not exceeded, it is advantageous in reducing aberrations in the second lens group.
By making sure that the upper limit of conditional expression (2) is not exceeded, the refractive power of the second lens group is secured, which is advantageous for securing the zooming function of the second lens group and shortening the overall length.

Moreover, it is preferable that the biconcave negative lens of the first lens group satisfies the following conditions.
nd _G1L1 > 1.75 (3)
However,
nd _G1L1 is the refractive index of the biconcave negative lens of the first lens group,
It is.

  When the conditional expression (3) is satisfied, the lens closest to the object side in the first lens group can have a sufficient negative refractive power with an appropriate curvature, which is preferable in terms of downsizing and aberration correction.

Moreover, it is preferable that the biconcave negative lens of the first lens group satisfies the following conditions.
νd _G1L1 > 60 (4)
However,
νd _G1L1 is the Abbe number of the biconcave negative lens in the first lens group,
It is.

  When the conditional expression (4) is satisfied, it is advantageous for the correction of chromatic aberration of the first lens group, which is preferable.

Moreover, it is preferable that the biconcave negative lens of the first lens group has a biconcave shape that satisfies the following conditions.
_−0.95 <(r _L11f + r _L11r ) / (r _L11f −r _L11r ) <0.95 (5)
However,
r _L11f is the paraxial radius of curvature of the object side surface of the biconcave negative lens in the first lens group,
r _L11r is the paraxial radius of curvature of the image side surface of the biconcave negative lens in the first lens group,
It is.

Conditional expression (5) relates to the biconcave negative lens closest to the object side in the first lens group of the three-group zoom lens.
By making sure that the lower limit of conditional expression (5) is not exceeded, the negative refractive power of the biconcave negative lens is prevented from concentrating on the object side surface, and the occurrence of off-axis aberrations can be easily suppressed.
By avoiding exceeding the upper limit of conditional expression (5), the curvature of the image side surface of the biconcave negative lens can be suppressed, and the positive lens in contact with the biconcave negative lens can be prevented from having an extreme meniscus shape. It becomes easy.

In addition, it is preferable that the positive lens in contact with the biconcave lens of the first lens group has a shape that satisfies the following conditions.
−40.0 <(r _L12f + r _L12r ) / (r _L12f −r _L12r ) <− 0.95 (6)
However,
r _L12f is the paraxial radius of curvature of the object side of the positive lens in the first lens group,
r _L12r is the paraxial radius of curvature of the image side of the positive lens in the first lens group,
It is.

Condition (6) relates to a positive lens in contact with the biconcave lens of the first lens group.
By making it not fall below the lower limit of the condition (6), the curvature of the concave surface of the image side surface can be moderately suppressed, and it becomes easy to mainly suppress the occurrence of off-axis aberrations.
By making so as not to exceed the upper limit of the condition (6), it is possible to easily suppress the curvature of the object side surface of the negative lens, and mainly to suppress the occurrence of axial aberration.

Further, when the total number of lenses of the three-group zoom lens is expressed as N, it is preferable that the following conditional expression is satisfied.
6 ≦ N ≦ 7 (7)
It is easy to balance aberration correction, miniaturization, high performance, and cost.
By making sure that the lower limit of conditional expression (7) is not exceeded, it becomes easy to improve the balance between aberration correction and high performance.
By making sure that the upper limit of conditional expression (7) is not exceeded, cost reduction and size reduction are facilitated.

In addition, it is preferable that the most object side lens surface in the second lens group is an aspherical surface.
By making the most object side surface of the second lens group an aspherical surface, it is advantageous to satisfactorily correct spherical aberration in all states from the wide-angle end to the telephoto end.

The second lens group preferably includes a lens component having a positive lens, a negative lens, and a positive lens in order from the object side.
This symmetrical refractive power arrangement of the lens components is advantageous for correcting spherical aberration and off-axis aberrations. The positive lens, the negative lens, and the positive lens are cemented in this order, so that the mutual decentration between the lenses can be reduced, the refractive power of the second lens group can be easily secured, and a high zoom ratio can be achieved. It will be advantageous.
Furthermore, it is preferable that the second lens group includes one lens component. This is advantageous for downsizing the second lens group.

Further, the second lens group may be composed of two lens components each having a cemented surface.
By configuring the second lens group to have two cemented lens components, chromatic aberration in each lens component can be suppressed. Since there are four lens surfaces in contact with air, it is advantageous for adjusting the principal point of the second lens group and reducing various aberrations.
Furthermore, it is preferable that each lens component of the second lens group is a doublet.
Since the total number of lenses in the second lens group is 4, it is advantageous for size reduction and cost reduction.

In zooming from the wide-angle end to the telephoto end, it is preferable that the second lens group moves while satisfying the following conditions.
0.5 <ΔG2 / f _w <3.0 (8)
However,
ΔG2 is the amount of change in position at the telephoto end with respect to the position at the wide-angle end of the second lens group,
The change to the object side is a positive sign.

Conditional expression (8) relates to the amount of movement of the second lens unit that provides a good balance between size and aberration.
By making sure that the lower limit of conditional expression (8) is not exceeded, it is easy to obtain a zooming function without increasing the refractive power of the second lens unit, and this is advantageous in reducing aberration fluctuations.
By not exceeding the upper limit of conditional expression (8), the amount of movement of the second lens group can be reduced appropriately, which is advantageous for reducing the overall length of the third group zoom lens.

  Further, when the third lens group is configured with a lens component having a positive refractive power, it is easy to make light rays incident on the image pickup device close to the vertical, and it is easy to suppress the influence of shading and the like.

On the other hand, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-351972, an image sensor is considered that reduces the influence of oblique incidence of light as the distance from the center increases.
Corresponding to such an image sensor, the third lens group may be composed of a lens component having a negative refractive power. The size of the third group zoom lens can be reduced with respect to the effective image pickup area of the image pickup device, which is advantageous for downsizing.

Further, focusing may be performed by moving the third lens group in the optical axis direction.
Since the third lens group is likely to be smaller than the first lens group and the second lens group, it is easy to reduce the burden of driving for focusing.

In addition, an imaging apparatus according to the present invention includes a third group zoom lens and an image sensor that is disposed on the image side of the third group zoom lens and converts an optical image formed by the third group zoom lens into an electrical signal. The third group zoom lens is any one of the third group zoom lenses described above.
It is possible to provide an image pickup apparatus including a three-group zoom lens that is small and has excellent optical performance.

Furthermore, it is preferable to have an image conversion unit that converts an electrical signal including distortion by the three-group zoom lens into an image signal in which distortion is corrected by image processing.
By electrically correcting the distortion, it is possible to reduce the aberration correction burden of the third group zoom lens itself, and it is easy to secure the negative refractive power of the first lens group, which is advantageous for a small and high zoom ratio.
The distortion correction amount may be changed for each color signal, and the chromatic aberration of magnification may be corrected by image processing.
It is more preferable to satisfy any one of the above-described configurations at the same time in terms of further miniaturization and higher performance.

  In addition, each conditional expression described above is configured in a state in which it is focused on the farthest distance when the three-group zoom lens has a focusing function.

Moreover, it is more preferable to limit the above conditional expressions as follows.
Regarding condition (1), the lower limit is preferably 0.1, and more preferably 0.2.
The upper limit value is preferably 0.6, and more preferably 0.5.
Regarding condition (2), the lower limit is preferably 0.8, more preferably 1.0.
The upper limit is preferably 4.0, and more preferably 3.0.
Regarding condition (3), the lower limit is preferably 1.80, more preferably 1.85.
The upper limit may be in the range where the glass material exists, but if it exceeds 20, the surface accuracy becomes severe, so it is preferable not to exceed 20.
Regarding condition (4), the lower limit is preferably set to 65, and more preferably 70.
If an upper limit value is also provided so as not to exceed 95, it is easy to reduce the influence on the secondary spectrum due to anomalous dispersion.
Regarding condition (5), the lower limit is preferably -0.5, more preferably -0.2.
It is preferable to set the upper limit value to 0.5, more preferably 0.2.
Regarding condition (6), the lower limit is preferably −30.0, more preferably −20.0.
The upper limit value is preferably -1.1, more preferably -1.2.
Regarding condition (8), the lower limit is preferably 1.0, more preferably 1.5.
The upper limit value is preferably 2.5, and more preferably 2.0.

  It is more preferable that each of the above-described inventions satisfies a plurality at the same time. For each conditional expression, only the upper limit value or lower limit value of the numerical range of the more limited conditional expression may be limited. Further, the above-described configurations may be arbitrarily combined.

  According to the present invention, it is easy to suppress aberration fluctuations even if the second lens group has a zooming load, and it is possible to provide a three-group zoom lens that is advantageous for downsizing and reducing relative decentration between lenses.

  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.

Each of the following examples achieves a zoom ratio of about 3 times, secures a wide angle half angle of view, and has good optical performance. Negative, positive, positive types (Examples 1-6, 11-11) 17, 22), or a negative, positive, negative type (Examples 7 to 10, 18 to 21) three-group zoom lens.
In the first to eleventh embodiments, the effective imaging area is rectangular and constant in the full zoom state.

The value corresponding to the conditional expression in each embodiment is a value in a state where an object point at infinity is in focus.
The total length is obtained by adding back focus to the distance on the optical axis from the entrance surface to the exit surface of the lens. The back focus is indicated by the air equivalent length.

As will be described later in each embodiment, the first lens unit moves to the image side after moving to the image side upon zooming from the wide-angle end to the telephoto end. The second lens group moves only to the object side. The third lens group varies as follows according to each embodiment.
In Examples 1 to 4, the third lens group moves only to the object side.
In Examples 5 and 6, the third lens unit moves only to the image side.
In Examples 7 and 8, the third lens group moves only to the object side.
In Examples 9 and 10, the third lens unit moves only to the image side.
In Example 11, the third lens unit moves only to the object side.

Focusing is performed by moving the third lens unit in the optical axis direction. In Examples 1 to 6, 11 in which the third lens unit has a positive refractive power, the focusing operation from a long distance object point to a short distance object point is performed. The three lens groups are moved to the object side.
In Examples 7 to 10 in which the third lens group has a negative refractive power, the focusing operation from the long distance object point to the short distance object point is performed by moving the third lens group to the image side.
As will be described later, the parallel plate is a low-pass filter and a CCD cover glass having an IR cut coat.

  Examples 1 to 11 of the zoom lens according to the present invention will be described below. FIGS. 1 to 11 show lens cross sections of the wide-angle end (a), the intermediate focal length 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 aperture stop is S, the second lens group is G2, the flare stop is FS, the third lens group is G3, and a wavelength region limiting coat that limits infrared light. The parallel flat plate constituting the applied low-pass filter is indicated by F, the parallel flat plate of the cover glass of the electronic image 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. Further, the cover glass C may have a low-pass filter action.

  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). Further, zoom data is values at the wide-angle end (WE), the intermediate focal length state (ST), and the telephoto end (TE).

  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 flare stop FS and a third lens group G3 having a positive refractive power are disposed.

  At the time of zooming from the wide angle end to the telephoto end, the first lens group G1 moves to the object side after moving to the image side. The second lens group G2 moves only to the object side. The third lens group G3 moves only to the object side.

  In order from the object side, the first lens group G1 includes a cemented lens which is formed by 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 cemented lens including a positive meniscus lens having a convex surface directed toward the object side, a negative meniscus lens having a convex surface directed toward the object side, and a positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 is composed of a biconvex positive lens.

  The aspheric surfaces are the object side surface of the biconcave negative lens of the first lens group G1, the image side surface of the positive meniscus lens having a convex surface facing the object side, and the object side closest to the object side of the second lens group G2. The object-side surface of the positive meniscus lens with the convex surface facing the surface, the image-side surface of the positive meniscus lens with the convex surface closest to the object side on the image side, and the object-side surface of the biconvex positive lens of the third lens group G3 It is used for 5 surfaces.

  As shown in FIG. 2, 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 flare stop FS and a third lens group G3 having a positive refractive power are disposed.

  At the time of zooming from the wide angle end to the telephoto end, the first lens group G1 moves to the object side after moving to the image side. The second lens group G2 moves only to the object side. The third lens group G3 moves only to the object side.

  In order from the object side, the first lens group G1 includes a cemented lens which is formed by 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 cemented lens including a positive meniscus lens having a convex surface directed toward the object side, a negative meniscus lens having a convex surface directed toward the object side, and a positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 is composed of a biconvex positive lens.

  The aspherical surface has both the double-concave negative lens of the first lens group G1, the image-side surface of the positive meniscus lens having a convex surface facing the object side, and the convex surface on the object side closest to the object side of the second lens group G2. The object-side surface of the positive meniscus lens directed to the surface, the image-side surface of the positive meniscus lens having the convex surface closest to the object side on the image side, and the object-side surface of the biconvex positive lens of the third lens group G3 Used on six sides.

  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 flare stop FS and a third lens group G3 having a positive refractive power are disposed.

  At the time of zooming from the wide angle end to the telephoto end, the first lens group G1 moves to the object side after moving to the image side. The second lens group G2 moves only to the object side. The third lens group G3 moves only to the object side.

  In order from the object side, the first lens group G1 includes a cemented lens which is formed by 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 cemented lens including a positive meniscus lens having a convex surface directed toward the object side, a negative meniscus lens having a convex surface directed toward the object side, and a positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 is composed of a cemented lens made up of a biconvex positive lens and a positive meniscus lens having a convex surface directed toward the image side.

  The aspheric surfaces are the object side surface of the biconcave negative lens of the first lens group G1, the image side surface of the positive meniscus lens having a convex surface facing the object side, and the object side closest to the object side of the second lens group G2. The object-side surface of the positive meniscus lens with the convex surface facing the surface, the image-side surface of the positive meniscus lens with the convex surface closest to the object side on the image side, and the object-side surface of the biconvex positive lens of the third lens group G3 It is used for 5 surfaces.

  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 flare stop FS and a third lens group G3 having a positive refractive power are disposed.

  At the time of zooming from the wide angle end to the telephoto end, the first lens group G1 moves to the object side after moving to the image side. The second lens group G2 moves only to the object side. The third lens group G3 moves only to the object side.

  In order from the object side, the first lens group G1 includes a cemented lens which is formed by 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 cemented lens including a positive meniscus lens having a convex surface directed toward the object side, a negative meniscus lens having a convex surface directed toward the object side, and a positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 is composed of a cemented lens made up of a biconvex positive lens and a positive meniscus lens having a convex surface directed toward the image side.

  The aspherical surface has both the double-concave negative lens of the first lens group G1, the image-side surface of the positive meniscus lens having a convex surface facing the object side, and the convex surface on the object side closest to the object side of the second lens group G2. The object-side surface of the positive meniscus lens directed to the surface, the image-side surface of the positive meniscus lens having the convex surface closest to the object side on the image side, and the object-side surface of the biconvex positive lens of the third lens group G3 Used on six sides.

  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.

  At the time of zooming from the wide angle end to the telephoto end, the first lens group G1 moves to the object side after moving to the image side. The second lens group G2 moves only to the object side. The third lens group G3 moves only to the image side.

  In order from the object side, the first lens group G1 includes a cemented lens which is formed by 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 cemented lens of a biconvex positive lens and a biconcave negative lens, and a cemented lens of a biconvex positive lens and a biconcave negative lens. The third lens group G3 is composed of a biconvex positive lens.

  The aspherical surfaces are the object-side surface of the biconcave negative lens of the first lens group G1, the image-side surface of the positive meniscus lens with the convex surface facing the object side, and the most object-side biconvex of the second lens group G2. It is used for five surfaces, that is, the object side surface of the positive lens, the image side surface of the biconcave negative lens closest to the object side, and the image side surface of the biconvex positive lens of the third lens group 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.

  At the time of zooming from the wide angle end to the telephoto end, the first lens group G1 moves to the object side after moving to the image side. The second lens group G2 moves only to the object side. The third lens group G3 moves only to the image side.

  In order from the object side, the first lens group G1 includes a cemented lens which is formed by 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 cemented lens of a biconvex positive lens and a biconcave negative lens, and a cemented lens of a biconvex positive lens and a biconcave negative lens. The third lens group G3 is composed of a biconvex positive lens.

  The aspherical surface includes both surfaces of a biconcave negative lens of the first lens group G1, an image side surface of a positive meniscus lens having a convex surface facing the object side, and a biconvex positive lens closest to the object side of the second lens group G2. It is used for five surfaces: the object side surface, the image side surface of the biconcave negative lens closest to the object side, and the image side surface of the biconvex positive lens of the third lens group 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 flare stop FS and a third lens group G3 having negative refractive power are arranged.

  At the time of zooming from the wide angle end to the telephoto end, the first lens group G1 moves to the object side after moving to the image side. The second lens group G2 moves only to the object side. The third lens group G3 moves only to the object side.

  In order from the object side, the first lens group G1 includes a cemented lens which is formed by 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 cemented lens including a positive meniscus lens having a convex surface directed toward the object side, a negative meniscus lens having a convex surface directed toward the object side, and a positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 is composed of a negative meniscus lens having a convex surface directed toward the image side.

  The aspheric surfaces are the object side surface of the biconcave negative lens of the first lens group G1, the image side surface of the positive meniscus lens having a convex surface facing the object side, and the object side closest to the object side of the second lens group G2. The object side surface of the positive meniscus lens with the convex surface facing the surface, the image side surface of the positive meniscus lens with the convex surface closest to the object side on the image side, and the negative surface with the convex surface facing the image side of the third lens group G3. It is used on five surfaces, the object side surface of the meniscus lens.

  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 flare stop FS and a third lens group G3 having negative refractive power are arranged.

  At the time of zooming from the wide angle end to the telephoto end, the first lens group G1 moves to the object side after moving to the image side. The second lens group G2 moves only to the object side. The third lens group G3 moves only to the object side.

  In order from the object side, the first lens group G1 includes a cemented lens which is formed by 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 cemented lens including a positive meniscus lens having a convex surface directed toward the object side, a negative meniscus lens having a convex surface directed toward the object side, and a positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 is composed of a negative meniscus lens having a convex surface directed toward the image side.

  The aspherical surface has both surfaces of the biconcave negative lens of the first lens group G1, the image side surface of the positive meniscus lens having a convex surface facing the object side, and the convex surface facing the object side closest to the object side of the second lens group G2. The object side surface of the positive meniscus lens, the image side surface of the positive meniscus lens with the convex surface facing the object side closest to the image side, and the object of the negative meniscus lens with the convex surface facing the image side of the third lens group G3 It is used on six sides with the side surface.

  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 negative refractive power is disposed.

  At the time of zooming from the wide angle end to the telephoto end, the first lens group G1 moves to the object side after moving to the image side. The second lens group G2 moves only to the object side. The third lens group G3 moves only to the image side.

  In order from the object side, the first lens group G1 includes a cemented lens which is formed by 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 cemented lens of a biconvex positive lens and a positive meniscus lens having a convex surface facing the image side, a negative meniscus lens having a convex surface facing the image side, and a negative meniscus lens having a convex surface facing the image side. The cemented lens. The third lens group G3 is composed of a biconcave negative lens.

  The aspherical surfaces are the object-side surface of the biconcave negative lens of the first lens group G1, the image-side surface of the positive meniscus lens with the convex surface facing the object side, and the most object-side biconvex of the second lens group G2. There are five surfaces: the object side surface of the positive lens, the image side surface of the positive meniscus lens having the convex surface closest to the image side on the object side, and the image side surface of the biconcave negative lens of the third lens group G3. Used.

  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, A third lens group G3 having a negative refractive power is disposed.

  At the time of zooming from the wide angle end to the telephoto end, the first lens group G1 moves to the object side after moving to the image side. The second lens group G2 moves only to the object side. The third lens group G3 moves only to the image side.

  In order from the object side, the first lens group G1 includes a cemented lens which is formed by 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 cemented lens of a biconvex positive lens and a positive meniscus lens having a convex surface facing the image side, a negative meniscus lens having a convex surface facing the image side, and a negative meniscus lens having a convex surface facing the image side. The cemented lens. The third lens group G3 is composed of a biconcave negative lens.

  The aspherical surface includes both surfaces of a biconcave negative lens of the first lens group G1, an image side surface of a positive meniscus lens having a convex surface facing the object side, and a biconvex positive lens closest to the object side of the second lens group G2. It is used for six surfaces: an object side surface, an image side surface of a positive meniscus lens having a convex surface closest to the image side on the object side, and an image side surface of the biconcave negative lens of the third lens group G3. .

  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, A flare stop FS and a third lens group G3 having a positive refractive power are disposed.

  At the time of zooming from the wide angle end to the telephoto end, the first lens group G1 moves to the object side after moving to the image side. The second lens group G2 moves only to the object side. The third lens group G3 moves only to the object side.

  In order from the object side, the first lens group G1 includes a cemented lens which is formed by 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 cemented lens including a positive meniscus lens having a convex surface directed toward the object side, a negative meniscus lens having a convex surface directed toward the object side, and a positive 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 object side.

  The aspherical surface has both the double-concave negative lens of the first lens group G1, the image-side surface of the positive meniscus lens having a convex surface facing the object side, and the convex surface on the object side closest to the object side of the second lens group G2. Of the positive meniscus lens directed toward the object side, the image side surface of the positive meniscus lens having the convex surface closest to the image side closest to the object side, and the positive meniscus lens having the convex surface directed toward the object side of the third lens group G3 It is used on 6 sides consisting of both sides.

Below, the numerical data of each said Example are shown. Symbols are the above, f is the focal length of the entire system, BF is the back focus, f1, f2... Are the focal lengths of the lens groups, IH is the image height, _FNO is the F number, ω is the half field angle, and WE is the wide angle. ST, intermediate focal length state, TE telephoto end, r1, r2..., Radius of curvature of each lens surface, d1, d2..., Spacing between lens surfaces, nd1, nd2. The ratio, νd1, νd2,... 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. BF (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 formula, where x is an optical axis with the light traveling direction being positive, and y is a direction orthogonal to the optical axis.

x = (y ² / r) / [1+ {1- (K + 1) (y / r) ² } ^1/2 ]
+ A ₄ y ⁴ + A ₆ y ⁶ + A ₈ y ⁸ + A ₁₀ y ¹⁰ + A ₁₂ y ¹²
Where r is the paraxial radius of curvature, K is the conic coefficient, and A ₄ , A ₆ , A ₈ , A ₁₀ , and A ₁₂ are the 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 νd
1 * -14.278 0.70 1.90366 31.32
2 11.423 2.19 1.94595 17.98
3 * 101.992 variable
4 (Brightness stop) ∞ -0.40
5 * 4.853 2.00 1.80610 40.73
6 6.262 0.70 1.84666 23.78
7 3.448 2.00 1.58313 59.38
8 * 7.042 0.74
9 (Flare aperture) ∞ Variable
10 * 14.000 1.40 1.49700 81.54
11 -20.483 Variable
12 ∞ 0.50 1.51633 64.14
13 ∞ 0.50
14 ∞ 0.50 1.51633 64.14
15 ∞ 0.42
Image surface (light receiving surface) ∞


Aspheric data first surface
k = 0.000, A4 = 7.74415e-05, A6 = 1.92625e-05, A8 = -6.74734e-07, A10 = 7.65589e-09
Third side
k = 0.000, A4 = 2.19531e-06, A6 = 2.08307e-05, A8 = -8.42305e-07, A10 = 1.11273e-08
5th page
k = -1.653, A4 = 1.64937e-03, A6 = 1.77730e-05, A8 = -5.69688e-07, A10 = 4.77908e-08
8th page
k = 0.709, A4 = 2.24931e-03, A6 = 1.47533e-04, A8 = -2.26007e-06, A10 = 8.19389e-07
10th page
k = 0.000, A4 = 9.99841e-05, A6 = 1.25435e-05, A8 = -1.26758e-06, A10 = 4.12786e-08

Scaling ratio 2.865
Group focal length
f1 = -14.36 f2 = 15.70 f3 = 16.96

Various data
WE ST TE
Image height 3.84 3.84 3.84
Focal length 7.51 13.50 21.51
FNO. 3.84 4.87 6.00
Angle of view 2ω 62.40 34.20 20.88
BF 9.77 14.47 21.92
Total length 39.66 37.53 38.96
d3 17.59 7.75 2.43
d9 2.97 5.98 5.27
d11 8.18 12.89 20.32

Numerical example 2
Unit mm

Surface data Surface number rd nd νd
1 * -14.202 0.70 1.90366 31.32
2 * 11.602 2.06 1.94595 17.98
3 * 100.000 variable
4 (Brightness stop) ∞ -0.40
5 * 4.895 2.00 1.80610 40.73
6 6.312 0.70 1.84666 23.78
7 3.493 2.00 1.58313 59.38
8 * 7.286 0.74
9 (Flare aperture) ∞ Variable
10 * 16.641 1.44 1.49700 81.54
11 -17.351 Variable
12 ∞ 0.50 1.51633 64.14
13 ∞ 0.50
14 ∞ 0.50 1.51633 64.14
15 ∞ 0.42
Image surface (light receiving surface) ∞

Aspheric data first surface
k = 0.000, A4 = 9.96784e-05, A6 = 1.88177e-05, A8 = -6.94583e-07, A10 = 8.21071e-09
Second side
k = 1.014, A4 = 3.62106e-04, A6 = -3.16045e-05, A8 = 8.37338e-07, A10 = -5.03458e-09
Third side
k = 0.000, A4 = 3.52517e-05, A6 = 1.98363e-05, A8 = -8.69684e-07, A10 = 1.24506e-08
5th page
k = -1.669, A4 = 1.63669e-03, A6 = 1.85525e-05, A8 = -5.86746e-07, A10 = 4.17552e-08
8th page
k = 0.817, A4 = 2.29412e-03, A6 = 1.47421e-04, A8 = 1.37442e-06, A10 = 2.88869e-07
10th page
k = 0.000, A4 = 1.55155e-04, A6 = 1.10296e-05, A8 = -1.02387e-06, A10 = 3.11979e-08

Scaling ratio 2.880
Group focal length
f1 = -14.25 f2 = 15.56 f3 = 17.34

Various data
WE ST TE
Image height 3.84 3.84 3.84
Focal length 7.51 13.42 21.62
FNO. 3.82 4.83 6.00
Angle of view 2ω 62.40 34.15 20.72
BF 9.84 14.53 22.17
Total length 39.66 37.19 39.13
d3 17.61 7.90 2.54
d9 2.97 5.53 5.19
d11 8.27 12.95 20.59

Numerical Example 3
Unit mm

Surface data Surface number rd nd νd
1 * -14.017 0.70 1.90366 31.32
2 11.214 2.45 1.94595 17.98
3 * 120.518 variable
4 (Brightness stop) ∞ -0.40
5 * 4.995 2.09 1.80610 40.73
6 9.180 0.91 1.84666 23.78
7 3.878 2.00 1.58313 59.38
8 * 7.393 0.74
9 (Flare aperture) ∞ Variable
10 * 14.000 1.40 1.49700 81.54
11 -24.036 1.00 1.94595 17.98
12 -23.330 Variable
13 ∞ 0.50 1.51633 64.14
14 ∞ 0.50
15 ∞ 0.50 1.51633 64.14
16 ∞ 0.42
Image surface (light receiving surface) ∞

Aspheric data first surface
k = 0.000, A4 = 6.93898e-05, A6 = 2.02050e-05, A8 = -7.16655e-07, A10 = 8.24537e-09
Third side
k = 0.000, A4 = -5.40678e-06, A6 = 2.18912e-05, A8 = -9.29715e-07, A10 = 1.29057e-08
5th page
k = -1.753, A4 = 1.61802e-03, A6 = 1.30324e-05, A8 = -5.37442e-07, A10 = 4.61596e-08
8th page
k = 1.235, A4 = 2.46506e-03, A6 = 1.74410e-04, A8 = -6.80292e-06, A10 = 1.62237e-06
10th page
k = 0.000, A4 = 1.52134e-04, A6 = 1.19379e-05, A8 = -1.21368e-06, A10 = 4.06969e-08

Scaling ratio 2.880
Group focal length
f1 = -14.44 f2 = 14.49 f3 = 17.77

Various image heights 3.84 3.84 3.84
Focal length 7.51 13.44 21.62
FNO. 3.82 4.88 6.00
Angle of view 2ω 62.39 34.47 20.79
BF 8.69 12.93 20.60
Total length 39.66 37.63 38.83
d3 17.12 7.62 2.09
d9 2.97 6.19 5.25
d12 7.11 11.35 19.02

Numerical Example 4
Unit mm

Surface data Surface number rd nd νd
1 * -14.496 0.70 1.90366 31.32
2 * 11.651 1.60 1.94595 17.98
3 * 120.518 variable
4 (Brightness stop) ∞ -0.40
5 * 5.011 2.00 1.80610 40.73
6 9.861 0.90 1.84666 23.78
7 3.994 2.00 1.58313 59.38
8 * 7.362 0.64
9 (Flare aperture) ∞ Variable
10 * 14.000 1.40 1.49700 81.54
11 -25.543 1.00 1.94595 17.98
12 -24.847 Variable
13 ∞ 0.50 1.51633 64.14
14 ∞ 0.50
15 ∞ 0.50 1.51633 64.14
16 ∞ 0.42
Image surface (light receiving surface) ∞

Aspheric data first surface
k = 0.000, A4 = 8.38894e-05, A6 = 2.14564e-05, A8 = -7.37668e-07, A10 = 8.01740e-09
Second side
k = 1.549, A4 = 3.21241e-04, A6 = -2.09401e-05, A8 = 4.65732e-07, A10 = -1.99254e-09
Third side
k = 0.000, A4 = 3.14284e-05, A6 = 2.28984e-05, A8 = -8.85930e-07, A10 = 1.09228e-08
5th page
k = -1.745, A4 = 1.62305e-03, A6 = 1.37282e-05, A8 = -4.14769e-07, A10 = 3.67154e-08
8th page
k = 1.277, A4 = 2.48100e-03, A6 = 1.74672e-04, A8 = -3.77235e-06, A10 = 1.25351e-06
10th page
k = 0.000, A4 = 1.59776e-04, A6 = 1.39303e-05, A8 = -1.32488e-06, A10 = 4.37187e-08

Scaling ratio 2.880
Group focal length
f1 = -14.92 f2 = 14.70 f3 = 18.20

Various data
WE ST TE
Image height 3.84 3.84 3.84
Focal length 7.51 13.50 21.62
FNO. 3.83 4.87 6.00
Angle of view 2ω 62.41 34.12 20.74
BF 8.70 12.92 20.17
Total length 39.66 36.64 37.64
d3 18.05 8.08 2.53
d9 3.07 5.81 5.10
d12 7.12 11.34 18.60

Numerical Example 5
Unit mm

Surface data Surface number rd nd νd
1 * -10.953 0.50 1.49700 81.54
2 15.249 1.15 1.84666 23.78
3 * 26.475 variable
4 (Brightness stop) ∞ -0.04
5 * 8.978 1.60 1.72916 54.68
6 -20.000 1.20 1.49700 81.54
7 * 74.759 0.10
8 7.513 1.75 1.83481 42.71
9 -9.872 1.74 1.76182 26.52
10 4.335 Variable
11 25.000 1.90 1.80610 40.92
12 * -12.236 variable
13 ∞ 0.40 1.54771 62.84
14 ∞ 0.50
15 ∞ 0.50 1.51633 64.14
16 ∞ 0.42
Image surface (light receiving surface) ∞

Aspheric data first surface
k = 0.000, A4 = 5.54348e-04, A6 = -8.86833e-06, A8 = 2.21670e-07, A10 = -2.53096e-09
Third side
k = 0.000, A4 = 1.83539e-04
5th page
k = 0.000, A4 = -1.39402e-04, A6 = 6.29470e-05, A8 = -1.20011e-05, A10 = 9.09887e-07
7th page
k = 0.000, A4 = 5.75303e-04, A6 = 6.03497e-05, A8 = -1.13984e-05, A10 = 9.36213e-07
12th page
k = 0.000, A4 = 5.72875e-04, A6 = -2.78681e-05, A8 = 8.49030e-07, A10 = -1.01158e-08

Scaling ratio 2.882
Group focal length
f1 = -18.18 f2 = 10.10 f3 = 10.43

Various data
WE ST TE
Image height 3.84 3.84 3.84
Focal length 6.80 13.73 19.60
FNO. 3.02 4.68 6.00
Angle of view 2ω 65.02 30.92 22.08
BF 4.05 3.26 2.91
Total length 27.80 27.39 29.69
d3 10.74 3.88 1.59
d10 3.12 10.34 15.30
d12 2.54 1.76 1.39

Numerical Example 6
Unit mm

Surface data Surface number rd nd νd
1 * -13.115 0.50 1.49700 81.54
2 * 13.089 1.15 1.84666 23.78
3 * 19.241 Variable
4 (Brightness stop) ∞ -0.04
5 * 8.477 1.60 1.72916 54.68
6 -12.993 1.20 1.49700 81.54
7 * 22.664 0.10
8 6.856 1.75 1.83481 42.71
9 -11.411 1.79 1.80518 25.42
10 4.409 Variable
11 25.000 1.90 1.80610 40.92
12 * -11.147 variable
13 ∞ 0.40 1.54771 62.84
14 ∞ 0.50
15 ∞ 0.50 1.51633 64.14
16 ∞ 0.42
Image surface (light receiving surface) ∞

Aspheric data first surface
k = 0.000, A4 = 1.92159e-04, A6 = 4.30887e-06, A8 = -1.22142e-07, A10 = 1.24604e-10
Second side
k = -0.594, A4 = 5.50339e-05, A6 = -2.06673e-05, A8 = 5.14911e-07
Third side
k = 0.000, A4 = -1.07581e-05
5th page
k = 0.000, A4 = -5.46476e-06, A6 = 4.75856e-05, A8 = -8.22022e-06, A10 = 5.24732e-07
7th page
k = 0.000, A4 = 9.79257e-04, A6 = 3.00855e-05, A8 = -2.56486e-06, A10 = 1.36875e-07
12th page
k = 0.000, A4 = 7.34585e-04, A6 = -2.93842e-05, A8 = 8.41145e-07, A10 = -9.79956e-09

Scaling ratio 2.882
Group focal length
f1 = -17.95 f2 = 9.86 f3 = 9.79

Various data
WE ST TE
Image height 3.84 3.84 3.84
Focal length 6.80 13.73 19.60
FNO. 3.02 4.68 6.00
Angle of view 2ω 64.01 30.35 21.67
BF 3.85 3.22 3.01
Total length 27.43 27.15 29.69
d3 10.54 3.85 1.59
d10 3.08 10.13 15.15
d12 2.35 1.72 1.49

Numerical Example 7
Unit mm

Surface data Surface number rd nd νd
1 * -17.195 0.70 1.90366 31.32
2 15.385 1.59 1.94595 17.98
3 * 100.000 variable
4 (Brightness stop) ∞ -0.40
5 * 4.270 2.05 1.80610 40.73
6 8.640 0.70 1.84666 23.78
7 3.448 2.05 1.58313 59.38
8 * 10.474 0.64
9 (Flare aperture) ∞ Variable
10 * -21.866 1.40 1.49700 81.54
11 -39.724 Variable
12 ∞ 0.50 1.51633 64.14
13 ∞ 0.50
14 ∞ 0.50 1.51633 64.14
15 ∞ 0.40
Image surface (light receiving surface) ∞

Aspheric data first surface
k = 0.000, A4 = -1.78784e-04, A6 = 2.76422e-05, A8 = -7.00116e-07, A10 = 3.93777e-09
Third side
k = 0.000, A4 = -2.24857e-04, A6 = 3.82950e-05, A8 = -1.19949e-06, A10 = 9.01148e-09
5th page
k = -1.167, A4 = 1.65148e-03, A6 = 4.20736e-05, A8 = 1.26868e-06, A10 = 2.41296e-08
8th page
k = 13.113, A4 = 4.46574e-03, A6 = 1.54812e-04, A8 = 7.84953e-05, A10 = 6.83402e-06
10th page
k = 0.000, A4 = 8.52136e-04, A6 = 2.46109e-05, A8 = -1.66769e-06, A10 = 5.32946e-07

Scaling ratio 2.878
Group focal length
f1 = -16.73 f2 = 9.23 f3 = -100.49

Various data
WE ST TE
Image height 3.84 3.84 3.84
Focal length 7.51 13.06 21.60
FNO. 3.51 4.47 6.00
Angle of view 2ω 63.13 34.31 20.45
BF 4.56 5.81 9.90
Total length 32.76 26.53 26.45
d3 16.39 7.20 2.45
d9 3.07 4.78 5.36
d11 3.00 4.25 8.34

Numerical Example 8
Unit mm

Surface data Surface number rd nd νd
1 * -17.308 0.70 1.90366 31.32
2 * 16.048 1.00 1.94595 17.98
3 * 100.000 variable
4 (Brightness stop) ∞ -0.40
5 * 4.271 2.05 1.80610 40.73
6 8.578 0.70 1.84666 23.78
7 3.448 2.02 1.58313 59.38
8 * 10.473 0.64
9 (Flare aperture) ∞ Variable
10 * -20.803 1.40 1.49700 81.54
11 -36.578 Variable
12 ∞ 0.50 1.51633 64.14
13 ∞ 0.50
14 ∞ 0.50 1.51633 64.14
15 ∞ 0.42
Image surface (light receiving surface) ∞

Aspheric data first surface
k = 0.000, A4 = -1.62082e-04, A6 = 2.91039e-05, A8 = -6.77478e-07, A10 = 2.77738e-09
Second side
k = -7.780, A4 = 1.48650e-04, A6 = 3.03155e-05, A8 = -5.73951e-08, A10 = -2.86094e-08
Third side
k = 0.000, A4 = -2.17097e-04, A6 = 4.05765e-05, A8 = -1.09478e-06, A10 = 5.48292e-09
5th page
k = -1.161, A4 = 1.65505e-03, A6 = 4.06561e-05, A8 = 1.08671e-06, A10 = 6.57786e-08
8th page
k = 13.238, A4 = 4.49522e-03, A6 = 1.09698e-04, A8 = 8.56693e-05, A10 = 6.16944e-06
10th page
k = 0.000, A4 = 8.44619e-04, A6 = 1.12866e-05, A8 = 3.76746e-07, A10 = 3.88770e-07

Scaling ratio 2.880
Group focal length
f1 = -16.83 f2 = 9.25 f3 = -100.00

Various data
WE ST TE
Image height 3.84 3.84 3.84
Focal length 7.51 13.50 21.62
FNO. 3.52 4.55 6.00
Angle of view 2ω 62.65 33.08 20.40
BF 4.58 5.90 9.90
Total length 32.50 26.00 26.04
d3 16.73 7.06 2.66
d9 3.07 4.92 5.36
d11 3.00 4.32 8.32

Numerical Example 9
Unit mm

Surface data Surface number rd nd νd
1 * -12.658 0.50 1.49700 81.54
2 10.548 1.15 1.84666 23.78
3 * 11.669 Variable
4 (Brightness stop) ∞ -0.04
5 * 16.216 1.60 1.72916 54.68
6 -20.000 1.20 1.49700 81.54
7 * -4.309 0.10
8 -8.799 1.75 1.83481 42.71
9 -9.613 0.50 1.76182 26.52
10 -24.033 variable
11 -63.929 1.90 1.80610 40.92
12 * 46.967 variable
13 ∞ 0.40 1.54771 62.84
14 ∞ 0.50
15 ∞ 0.50 1.51633 64.14
16 ∞ 0.40
Image surface (light receiving surface) ∞

Aspheric data first surface
k = 0.000, A4 = 1.23221e-04, A6 = -3.54661e-06, A8 = 1.03494e-07, A10 = -9.58241e-10
Third side
k = 0.000, A4 = -5.10764e-05
5th page
k = 0.000, A4 = -2.10331e-03, A6 = -1.14105e-04, A8 = -1.82025e-05, A10 = -2.69682e-06
7th page
k = 0.000, A4 = -6.08013e-04, A6 = -2.86534e-05, A8 = -2.29854e-05, A10 = 4.90151e-07
12th page
k = 0.000, A4 = 1.20316e-03, A6 = 7.08569e-06, A8 = -3.62446e-06, A10 = 2.66828e-07

Scaling ratio 2.882
Group focal length
f1 = -12.59 f2 = 9.26 f3 = -33.33

Various data
WE ST TE
Image height 3.84 3.84 3.84
Focal length 6.80 13.73 19.60
FNO. 3.99 5.14 6.00
Angle of view 2ω 68.09 29.86 20.79
BF 4.32 4.15 2.67
Total length 34.69 29.21 30.08
d3 14.68 4.75 1.59
d10 7.03 11.66 17.17
d12 2.83 2.66 1.18

Numerical Example 10
Unit mm

Surface data Surface number rd nd νd
1 * -12.124 0.50 1.49700 81.54
2 * 11.109 1.15 1.84666 23.78
3 * 12.230 Variable
4 (Brightness stop) ∞ -0.04
5 * 15.848 1.60 1.72916 54.68
6 -20.000 1.20 1.49700 81.54
7 * -4.305 0.10
8 -8.555 1.75 1.83481 42.71
9 -9.656 0.50 1.76182 26.52
10 -22.922 Variable
11 -63.929 1.90 1.80610 40.92
12 * 46.967 variable
13 ∞ 0.40 1.54771 62.84
14 ∞ 0.50
15 ∞ 0.50 1.51633 64.14
16 ∞ 0.40
Image surface (light receiving surface) ∞

Aspheric data first surface
k = 0.000, A4 = 9.13160e-05, A6 = 2.72628e-07, A8 = 9.17430e-08, A10 = -1.73728e-09
Second side
k = 1.207, A4 = 1.95029e-04, A6 = -4.09681e-06, A8 = -3.66823e-07, A10 = 7.83972e-09
Third side
k = 0.000, A4 = 6.57630e-05
5th page
k = 0.000, A4 = -2.05760e-03, A6 = -1.10415e-04, A8 = -1.71201e-05, A10 = -2.79258e-06
7th page
k = 0.000, A4 = -5.76651e-04, A6 = -2.39611e-05, A8 = -2.29215e-05, A10 = 4.40799e-07
12th page
k = 0.000, A4 = 1.21846e-03, A6 = -1.87774e-06, A8 = -2.39335e-06, A10 = 2.19720e-07

Scaling ratio 2.882
Group focal length
f1 = -12.55 f2 = 9.27 f3 = -33.33

Various data
WE ST TE
Image height 3.84 3.84 3.84
Focal length 6.80 13.73 19.60
FNO. 3.99 5.14 6.00
Angle of view 2ω 68.03 29.87 20.78
BF 4.31 4.12 2.67
Total length 34.69 29.24 30.14
d3 14.66 4.74 1.59
d10 7.06 11.74 17.23
d12 2.83 2.67 1.18

Numerical Example 11
Unit mm

Surface data Surface number rd nd νd
1 * -23.713 0.70 1.90366 31.32
2 * 18.969 1.54 1.63494 23.22
3 * 100.000 variable
4 (Brightness stop) ∞ -0.40
5 * 4.385 2.18 1.80610 40.73
6 5.648 0.73 1.84666 23.78
7 3.450 2.13 1.58313 59.38
8 * 8.777 0.64
9 (Flare aperture) ∞ Variable
10 * 9.572 1.40 1.49700 81.54
11 * 12.809 Variable
12 ∞ 0.50 1.51633 64.14
13 ∞ 0.50
14 ∞ 0.50 1.51633 64.14
15 ∞ 0.41
Image surface (light receiving surface) ∞

Aspheric data first surface
k = 0.000, A4 = 2.22078e-04, A6 = 8.37534e-06, A8 = -8.16149e-07, A10 = 1.31562e-08
Second side
k = 1.014, A4 = 2.39436e-03, A6 = 4.09562e-05, A8 = -2.46113e-06, A10 = -1.60636e-08
Third side
k = 0.000, A4 = -7.89414e-04, A6 = 2.06410e-05, A8 = -1.32623e-06, A10 = 3.81678e-08
5th page
k = -1.430, A4 = 1.80630e-03, A6 = 4.88714e-05, A8 = -1.54594e-06, A10 = 1.11460e-07
8th page
k = 6.388, A4 = 3.94460e-03, A6 = 5.66061e-04, A8 = -4.60055e-05, A10 = 1.75053e-05
10th page
k = 0.000, A4 = -9.15114e-06, A6 = 6.05375e-05, A8 = 1.79123e-05, A10 = -4.84755e-07
11th page
k = 0.000, A4 = -6.32528e-04, A6 = -9.76173e-06, A8 = 1.82808e-05, A10 = 2.04038e-07

Scaling ratio 2.880
Group focal length
f1 = -16.88 f2 = 9.90 f3 = 66.64

Various data
WE ST TE
Image height 3.50 3.50 3.50
Focal length 7.51 13.51 21.62
FNO. 3.53 4.60 6.00
Angle of view 2ω 56.28 30.30 18.63
BF 4.57 6.91 11.71
Total length 31.70 26.11 26.12
d3 15.14 5.98 1.49
d9 3.07 4.30 4.00
d11 3.00 5.35 10.14

  Examples 12 to 22 are examples in which the zoom lenses of Examples 1 to 11 are used, respectively, and are used in an imaging apparatus that electrically corrects distortion, and the shape of the effective imaging region changes during zooming. Therefore, it is different from the embodiment corresponding to the image height and the angle of view in the zoom state.

  In Examples 11 to 22, images are recorded and displayed after electrically correcting barrel distortion generated on the wide angle side.

  In the zoom lens of this embodiment, barrel distortion occurs at the wide-angle end on the rectangular photoelectric conversion surface. On the other hand, the occurrence of distortion is suppressed near the intermediate focal length state and at the telephoto end.

  In order to electrically correct the distortion, the effective imaging area has a barrel shape at the wide angle end and a rectangular shape at the intermediate focal length state or the telephoto end. Then, the effective imaging area set in advance is image-converted by image processing and converted into rectangular image information with reduced distortion.

The maximum image height IH _w at the wide-angle end is made smaller than the maximum image height IH _{s at} the intermediate focal length state and the maximum image height IH _t at the telephoto end.
In Examples 11 to 22, the length in the short side direction of the photoelectric conversion surface at the wide-angle end is the same as the length in the short side direction of the effective imaging region, and the distortion after image processing is about −3%. The effective imaging area is determined so as to remain. Of course, an image obtained by converting a smaller barrel-shaped area into a rectangular shape as an effective imaging area may be recorded and reproduced.

The zoom lens of Example 12 is the same as the zoom lens of Example 1.
The zoom lens of the thirteenth embodiment is the same as the zoom lens of the second embodiment.
The zoom lens of Example 14 is the same as the zoom lens of Example 3.
The zoom lens of Example 15 is the same as the zoom lens of Example 4.
The zoom lens of Example 16 is the same as the zoom lens of Example 5.
The zoom lens of Example 17 is the same as the zoom lens of Example 6.
The zoom lens of Example 18 is the same as the zoom lens of Example 7.
The zoom lens of Example 19 is the same as the zoom lens of Example 8.
The zoom lens of Example 20 is the same as the zoom lens of Example 9.
The zoom lens of Example 21 is the same as the zoom lens of Example 10.
The zoom lens of Example 22 is the same as the zoom lens of Example 11.

Data of the image height and the total angle of view in Example 12 are shown below.
Various data
WE ST TE
Image height 3.59 3.84 3.84
Focal length 7.51 13.50 21.51
FNO. 3.84 4.87 6.00
Angle of view 2ω 57.78 34.20 20.88

Data of image height and full angle of view in Example 13 are shown below.
Various data
WE ST TE
Image height 3.58 3.84 3.84
Focal length 7.51 13.42 21.62
FNO. 3.82 4.83 6.00
Angle of view 2ω 57.74 34.15 20.72

Data of the image height and the total angle of view in Example 14 are shown below.
Various data
WE ST TE
Image height 3.59 3.84 3.84
Focal length 7.51 13.44 21.62
FNO. 3.82 4.88 6.00
Angle of view 2ω 57.79 34.47 20.79

Data of the image height and the total angle of view in Example 15 are shown below.
Various data
WE ST TE
Image height 3.59 3.84 3.84
Focal length 7.51 13.50 21.62
FNO. 3.83 4.87 6.00
Angle of view 2ω 57.81 34.12 20.74

Data of image height and full angle of view in Example 16 are shown below.
Various data
WE ST TE
Image height 3.64 3.84 3.84
Focal length 6.80 13.73 19.60
FNO. 3.02 4.68 6.00
Angle of view 2ω 61.61 30.92 22.08

Data of image height and full angle of view in Example 17 are shown below.
Various data
WE ST TE
Image height 3.68 3.84 3.84
Focal length 6.80 13.73 19.60
FNO. 3.02 4.68 6.00
Angle of view 2ω 61.28 30.35 21.67

Data of image height and full angle of view in Example 18 are shown below.
Various data
WE ST TE
Image height 3.57 3.84 3.84
Focal length 7.51 13.06 21.60
FNO. 3.51 4.47 6.00
Angle of view 2ω 57.97 34.31 20.45

Data of image height and full angle of view in Example 19 are shown below.
Various data
WE ST TE
Image height 3.58 3.84 3.84
Focal length 7.51 13.50 21.62
FNO. 3.52 4.55 6.00
Angle of view 2ω 57.86 33.08 20.40

Data on the image height and the total angle of view in Example 20 are shown below.
Various data
WE ST TE
Image height 3.55 3.84 3.84
Focal length 6.80 13.73 19.60
FNO. 3.99 5.14 6.00
Angle of view 2ω 62.23 29.86 20.79

Data of image height and full angle of view in Example 21 are shown below.
Various data
WE ST TE
Image height 3.55 3.84 3.84
Focal length 6.80 13.73 19.60
FNO. 3.99 5.14 6.00
Angle of view 2ω 62.25 29.87 20.78

Data of image height and full angle of view in Example 22 are shown below.
Various data
WE ST TE
Image height 3.31 3.50 3.50
Focal length 7.51 13.51 21.62
FNO. 3.53 4.60 6.00
Angle of view 2ω 52.97 30.30 18.63

  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.

Next, the values of conditional expressions (1) to (8) in each example will be listed.
Values corresponding to conditional expressions in each example
Example 1 Example 2 Example 3 Example 4 Example 5 Example 6
(1) D _G1 / f _w 0.39 0.37 0.42 0.31 0.24 0.24
(2) f _G2C1 / f _w 1.17 1.18 1.16 1.16 1.60 1.44
(3) nd _G1L1 1.90366 1.90366 1.90366 1.90366--
(4) νd _G1L1---- 81.54 81.54
(5) (r _L11f + r _L11r ) / (r _L11f -r _L11r )
0.11 0.10 0.11 0.11 -0.16 0.00
(6) (r _L12f + r _L12r ) / (r _L12f -r _L12r )
-1.25 -1.26 -1.21 -1.21 -3.72 -5.26
(7) N 6 6 7 7 7 7
(8) ΔG2 / f _w 1.93 1.94 1.89 1.80 1.62 1.65

Example 7 Example 8 Example 9 Example 10 Example 11
(1) D _G1 / f _w 0.31 0.23 0.24 0.24 0.30
(2) f _G2C1 / f _w 0.97 0.97 2.62 2.57 0.98
(3) nd _G1L1 1.90366 1.90366--1.90366
(4) νd _{G1L1--81.54 81.54-}
(5) (r _L11f + r _L11r ) / (r _L11f -r _L11r )
0.06 0.04 0.09 0.04 0.11
(6) (r _L12f + r _L12r ) / (r _L12f -r _L12r )
-1.36 -1.38 -19.82 -20.81 -1.47
(7) N 6 6 7 7 6
(8) ΔG2 / f _w 1.02 1.01 1.25 1.25 1.07

Example 12 Example 13 Example 14 Example 15 Example 16 Example 17
(1) D _G1 / f _w 0.39 0.37 0.42 0.31 0.24 0.24
(2) f _G2C1 / f _w 1.17 1.18 1.16 1.16 1.60 1.44
(3) nd _G1L1 1.90366 1.90366 1.90366 1.90366--
(4) νd _G1L1---- 81.54 81.54
(5) (r _L11f + r _L11r ) / (r _L11f -r _L11r )
0.11 0.10 0.11 0.11 -0.16 0.00
(6) (r _L12f + r _L12r ) / (r _L12f -r _L12r )
-1.25 -1.26 -1.21 -1.21 -3.72 -5.26
(7) N 6 6 7 7 7 7
(8) ΔG2 / f _w 1.93 1.94 1.89 1.80 1.62 1.65


Example 18 Example 19 Example 20 Example 21 Example 22
(1) D _G1 / f _w 0.31 0.23 0.24 0.24 0.30
(2) f _G2C1 / f _w 0.97 0.97 2.62 2.57 0.98
(3) nd _G1L1 1.90366 1.90366--1.90366
(4) νd _{G1L1--81.54 81.54-}
(5) (r _L11f + r _L11r ) / (r _L11f -r _L11r )
0.06 0.04 0.09 0.04 0.11
(6) (r _L12f + r _L12r ) / (r _L12f -r _L12r )
-1.36 -1.38 -19.82 -20.81 -1.47
(7) N 6 6 7 7 6
(8) ΔG2 / f _w 1.02 1.01 1.25 1.25 1.07

(Correction of distortion)
By the way, when the zoom lens of the present invention is used, image distortion is digitally corrected electrically. 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 to be corrected toward the center of the circle 6 radius r ₁ ′ (ω) 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 subject half angle of view, and f is the focal length of the imaging optical system (in the present invention, the zoom lens).

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 a manufacturing error of an optical system or an electronic imaging element in an electronic imaging device included in 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 the actual number of images, but the effect of reducing the size is ensured even if the angle 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. When the cover 160 is opened and the camera 140 is set to the photographing state, the photographing optical system 141 is brought into the non-collapsed state of FIG. 26, and when the shutter button 145 disposed on the upper side of the camera 140 is pressed, the photographing is interlocked. 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. Miniaturization and wide angle can be realized.

(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 can be realized. In addition, fast focusing operation on the wide-angle side and the telephoto side is possible.

  As described above, the three-group zoom lens according to the present invention is advantageous for downsizing and high performance, and is suitable for a lens that can easily suppress the influence of decentration between lenses.

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 perspective 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.

Explanation of symbols

G1 ... 1st lens group G2 ... 2nd lens group G3 ... 3rd lens group S ... Brightness stop FS ... Flare stop F ... Low pass filter C ... Cover glass I ... Image surface 112 ... Operation part 113 ... Control part 114 ... Bus DESCRIPTION OF SYMBOLS 115 ... Bus 116 ... Imaging drive circuit 117 ... Temporary storage memory 118 ... Image processing part 119 ... Storage medium part 120 ... Display part 121 ... Setting information storage memory part 122 ... Bus 124 ... CDS / ADC part 140 ... Digital camera 141 ... Photographing Optical system 142 ... Optical path for photographing 143 ... Optical system for viewfinder 144 ... Optical path for viewfinder 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 (21)

From the object side,
A first lens group having negative refractive power,
A second lens group having positive refractive power,
A third lens group having refractive power,
During zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group is narrowed, and the distance between the second lens group and the third lens group is changed,
When the lens component has only two lens bodies on the optical axis in contact with air, the object side surface and the image side surface,
The first lens group includes, in order from the object side, a lens component having one negative refracting power having a negative lens having a concave surface facing the image side and a positive lens having a convex surface facing the object side,
The second lens group includes at least one negative lens and a plurality of positive lenses, and at least three of the lenses are joined to an adjacent lens,
The total number of lens components included in the second lens group is 2 or less;
The third group zoom lens according to claim 3, wherein the third lens group includes one lens component including two or less lenses.   The three-group zoom lens according to claim 1, wherein the negative lens component in the first lens group has an aspheric cemented surface.   2. The three-group zoom lens according to claim 1, wherein the negative lens component in the first lens group has a spherical cemented surface. The three-group zoom lens according to claim 1, wherein the first lens group satisfies the following condition.
0.05 <D _G1 / f _w <0.8 (1)
However,
D _G1 is the thickness of the first lens group on the optical axis,
_fw is the focal length at the wide-angle end of the three-group zoom lens,
It is. 2. The three-unit zoom lens according to claim 1, wherein a lens component closest to the object side in the second lens unit is a cemented lens component that satisfies the following condition.
0.5 <f _G2C1 / f _w <5.0 (2)
However,
f _G2C1 is the focal length of the lens component closest to the object in the second lens group,
_fw is the focal length at the wide-angle end of the three-group zoom lens,
It is. The three-group zoom lens according to claim 1, wherein the negative lens of the first lens group satisfies the following condition.
nd _G1L1 > 1.75 (3)
However,
nd _G1L1 is the refractive index of the negative lens of the first lens group,
It is. The three-group zoom lens according to claim 1, wherein the negative lens of the first lens group satisfies the following condition.
νd _G1L1 > 60 (4)
However,
νd _G1L1 is the Abbe number of the negative lens of the first lens group,
It is. 2. The three-group zoom lens according to claim 1, wherein the negative lens of the first lens group has a biconcave shape that satisfies the following conditions.
_−0.95 <(r _L11f + r _L11r ) / (r _L11f −r _L11r ) <0.95 (5)
However,
r _L11f is the paraxial radius of curvature of the object side surface of the biconcave negative lens in the first lens group;
r _L11r is the paraxial radius of curvature of the image side surface of the biconcave negative lens in the first lens group;
It is. The three-group zoom lens according to claim 1, wherein the positive lens of the first lens group has a shape that satisfies the following conditions.
−40.0 <(r _L12f + r _L12r ) / (r _L12f −r _L12r ) <− 0.95 (6)
However,
r _L12f is the paraxial radius of curvature of the object side surface of the positive lens in the first lens group,
r _L12r is a paraxial radius of curvature of the image side surface of the positive lens in the first lens group;
It is. 2. The three-group zoom lens according to claim 1, wherein when the total number of lenses of the three-group zoom lens is expressed as N, the following conditional expression is satisfied.
6 ≦ N ≦ 7 (7)   2. The three-group zoom lens according to claim 1, wherein a lens surface closest to the object side in the second lens group is an aspherical surface.   2. The three-group zoom lens according to claim 1, wherein the second lens group includes a lens component including a positive lens, a negative lens, and a positive lens in order from the object side.   The three-group zoom lens according to claim 12, wherein the second lens group includes one lens component.   2. The three-group zoom lens according to claim 1, wherein the second lens group includes two lens components each having a cemented surface.   The zoom lens according to claim 14, wherein each lens component of the second lens group is a doublet. 2. The three-unit zoom lens according to claim 1, wherein the second lens unit moves while satisfying the following condition when zooming from the wide-angle end to the telephoto end.
0.5 <ΔG2 / f _w <3.0 (8)
However,
ΔG2 is the amount of change in the position at the telephoto end with respect to the position at the wide-angle end of the second lens group, and the change toward the object side is a positive sign.   The third group zoom lens according to claim 1, wherein the third lens group has a positive refractive power.   The three-group zoom lens according to claim 1, wherein the third lens group has a negative refractive power.   2. The three-group zoom lens according to claim 1, wherein the third lens group moves in an optical axis direction to perform focusing. A three-group zoom lens;
An image pickup apparatus including an image pickup device that is disposed on an image side of the third group zoom lens and converts an optical image formed by the third group zoom lens into an electric signal,
An image pickup apparatus, wherein the third group zoom lens is the third group zoom lens according to at least one of claims 1 to 19. 21. The imaging apparatus according to claim 20, further comprising an image conversion unit that converts the electrical signal including distortion by the third group zoom lens into an image signal in which the distortion is corrected by image processing.

Images