JP5501736B2 - Imaging optical system and electronic imaging apparatus having the same - Google Patents

Description

  The present invention relates to an imaging optical system and an electronic imaging apparatus having the same.

  In recent years, the thinning of compact cameras has progressed, and the optical system is also required to be thin in order to be housed in a thin camera casing. Here, in the compact camera, after use, the optical system is retracted and housed in the housing. For this reason, if a camera housing becomes thin, it is necessary to reduce a collapsible thickness in connection with it.

  In order to retract the optical system, the lens frame of the optical system is divided into a plurality of stages so that it can be expanded and contracted. At this time, when the retracted thickness is reduced, the length of each of the divided lens frames is also shortened, and the number of steps when retracting is increased. Further, since the entire lens frame is easily deformed by gravity when the optical system is extended for a long time, the optical system is likely to be decentered. Therefore, it is necessary to shorten the total length of the optical system in order to reduce the number of divisions while shortening the interval at which the lens frame is divided.

  In order to make the optical system thin, for example, as described in Examples 4, 6, and 7 of Patent Literature 1, it is preferable to form the first lens group with a single lens. However, in particular, when the overall length of the optical system is shortened, the power of the first lens group generally increases. For this reason, chromatic aberration such as axial chromatic aberration and chromatic aberration of magnification is greatly generated, resulting in deterioration of image quality. In order to suppress the occurrence of chromatic aberration, the first lens group requires at least two lenses (positive lens and negative lens). In this case, the first lens group is often composed of a cemented lens.

  As an optical system in which the first lens group is constituted by a cemented lens, for example, an optical system disclosed in Patent Document 2 is known. In this optical system, the first lens group is composed of a cemented lens of a positive lens and a negative lens in order from the object side.

Japanese Patent Laid-Open No. 11-258507 JP 2007-72117 A

  However, if the total length of the optical system is further shortened, the chromatic aberration cannot be corrected with the cemented lens as described above, and a large amount of chromatic aberration occurs particularly on the telephoto side. Further, the larger the zoom ratio, the longer the total length of the optical system at the telephoto end. For this reason, if the total length of the optical system having a large zoom ratio is shortened, the influence of chromatic aberration is further increased.

  In general, the partial dispersion ratio θgF of the low dispersion material is small, and the partial dispersion ratio θgF of the high dispersion material is large. For this reason, even if the chromatic aberration can be corrected between the two wavelengths of the C-line and the F-line, there is a problem that the residual chromatic aberration tends to increase at other wavelengths. This is called a secondary spectrum.

  The present invention has been made in view of the above, and an object of the present invention is to provide an imaging optical system capable of shortening the overall length of the optical system while suppressing chromatic aberration, and an electronic imaging apparatus having the same.

In order to solve the above-described problems and achieve the object, the imaging optical system of the present invention includes a plurality of lens groups, and the plurality of lens groups have a first refractive power in order from the object side. A lens group, a second lens group having negative refracting power, a third lens group having positive refracting power, and a final lens group, and a distance between adjacent lens groups upon zooming. The final lens group has a positive refractive power, the first lens group is composed of only one cemented lens component, and the cemented lens component includes one negative lens and two positive lenses. Are joined together,
The following conditional expression (1) is satisfied, the third lens group has only two single lenses, a positive lens and a negative lens, and the negative lens satisfies the following conditional expression (5): .
0.05 <ΔD12 / ((ΣD1 + ΣD2) × γ × tan ω) <0.19 (1)
2 <SF3 <10 (5)
here,
ΔD12 is represented by | D12T-D12W |
D12W is the distance between the first lens group and the second lens group at the wide-angle end,
D12T is the distance between the first lens group and the second lens group at the telephoto end.
ΣD1 is the thickness of the first lens group,
ΣD2 is the thickness of the second lens group,
γ is a zoom ratio from the wide-angle end to the telephoto end of the imaging optical system,
ω is the maximum angle of view,
SF3 is a shaping factor of the negative lens of the third lens group, and the shaping factor is a value defined by the following equation:
SF3 = (r31 + r32) / (r31-r32)
r31 is the radius of curvature of the object side surface of the negative lens of the third lens group;
r32 is the radius of curvature of the image side surface of the negative lens of the third lens group;
It is.

Moreover, according to the preferable aspect of this invention, it is preferable to satisfy the following conditional expressions (2).
-0.8 <ΔV2 / ΔV1 <0.8 (2)
here,
ΔV1 is represented by | V1W-V1T |
V1W is the position of the first lens group at the wide-angle end,
V1T is the position of the first lens group at the telephoto end,
ΔV2 is represented by | V2W-V2T |
V2W is the position of the second lens group at the wide-angle end,
V2T is the position of the second lens group at the telephoto end,
The sign is positive when each lens group is located on the object side at the telephoto end with respect to the position at the wide-angle end.

Moreover, according to the preferable aspect of this invention, it is preferable to satisfy the following conditional expressions (3).
-0.3 <ΔVL / fw <0.6 (3)
here,
ΔVL is represented by | VLW-VLT |
VLW is the position of the last lens group at the wide-angle end,
VLT is the position of the last lens group at the telephoto end,
fw is the focal length of the entire imaging optical system at the wide-angle end,
The sign is positive when the final lens group is located on the object side at the telephoto end with respect to the position at the wide-angle end.

  According to a preferred aspect of the present invention, it is preferable that at least one cemented surface of the cemented lens component is an aspheric surface.

  According to a preferred aspect of the present invention, it is preferable that the two positive lenses in the cemented lens component are arranged adjacent to each other, and the cemented surface of the two positive lenses is an aspherical surface.

Moreover, according to the preferable aspect of this invention, it is preferable to satisfy the following conditional expressions (4).
0.0005 <| (P0−Ph) / P0 | <0.3 (4)
here,
P0 is the power on the optical axis of the joint surface,
Ph is the local power at the beam height h of the joint surface,
The ray height h is the ray height at which the absolute value of the difference between the local power of the joint surface and the power on the optical axis is maximized.

According to a preferred aspect of the present invention, the final lens group consists of one positive lens,
It is preferable that the positive lens satisfies the following conditional expression (6).
-5 <SFL <0 (6)
here,
SFL is a shaping factor of the positive lens of the final lens group, and the shaping factor is a value defined by the following equation:
SFL = (rL1 + rL2) / (rL1-rL2))
rL1 is the radius of curvature of the object side surface of the positive lens in the last lens group,
rL2 is the radius of curvature of the image side surface of the positive lens in the last lens group,
It is.

According to a preferred aspect of the present invention, it is preferable that the cemented lens component satisfies the following conditional expression (7).
2 <f1T1 / f1 <15 (7)
here,
f1 is the focal length of the entire cemented lens component,
f1T1 is the focal length of the positive lens located on the object side, out of the two positive lenses included in the cemented lens component,
It is.

Moreover, according to the preferable aspect of this invention, it is preferable to satisfy the following conditional expressions (8).
0.60 <θgFT1 <0.80 (8)
here,
θgFT1 is the partial dispersion ratio (ngT1−nFT1) / (nFT1−nCT1) of the positive lens located on the object side of the two positive lenses included in the cemented lens component,
nCT1, nFT1, and ngT1 are refractive indexes of C-line, F-line, and g-line of the positive lens located on the object side,
It is.

  An electronic imaging apparatus according to the present invention includes the above-described imaging optical system and an electronic imaging element.

  According to the present invention, it is possible to provide an imaging optical system capable of shortening the entire length of the optical system while suppressing chromatic aberration, and to provide an electronic imaging apparatus having the same.

(A) of the zoom lens according to Example 1 of the present invention is a cross-sectional view along the optical axis showing an optical configuration at the time of focusing on an object point at infinity at the wide-angle end, (b) at the middle, and (c) at the telephoto end. is there. FIG. 2 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 1 is focused on an object point at infinity, where (a) is a wide angle end, (b) is an intermediate, and (c). Indicates the state at the telephoto end. (A) of the zoom lens according to Example 2 of the present invention is a cross-sectional view along the optical axis showing an optical configuration at the time of focusing on an object point at infinity at the wide-angle end, (b) at the middle, and (c) at the telephoto end. is there. FIG. 6 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 2 is focused on an object point at infinity, where (a) is a wide-angle end, (b) is a middle, and (c). Indicates the state at the telephoto end. (A) of the zoom lens according to Example 3 of the present invention is a cross-sectional view along the optical axis showing an optical configuration at the time of focusing on an object point at infinity at the wide-angle end, (b) at the middle, and (c) at the telephoto end. is there. FIG. 6 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 3 is focused on an object point at infinity, (a) is a wide-angle end, (b) is an intermediate, (c) Indicates the state at the telephoto end. (A) of the zoom lens according to Example 4 of the present invention is a cross-sectional view along the optical axis showing an optical configuration at the time of focusing on an object point at infinity at the wide-angle end, (b) at the middle, and (c) at the telephoto end. is there. FIG. 10 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 4 is focused on an object point at infinity, where (a) is a wide angle end, (b) is an intermediate, and (c). Indicates the state at the telephoto end. (A) of the zoom lens according to Example 5 of the present invention is a cross-sectional view along the optical axis showing the optical configuration at the time of focusing on an object point at infinity at the wide-angle end, (b) at the middle, and (c) at the telephoto end. is there. FIG. 10 is a diagram illustrating spherical aberration, astigmatism, distortion, and lateral chromatic aberration when the zoom lens according to Example 5 is focused on an object point at infinity, where (a) is a wide angle end, (b) is an intermediate, and (c). Indicates the state at the telephoto end. (A) of the zoom lens according to Example 6 of the present invention is a cross-sectional view along the optical axis showing an optical configuration at the time of focusing on an object point at infinity at the wide-angle end, (b) at the middle, and (c) at the telephoto end. is there. FIG. 8 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 6 is focused on an object point at infinity, where (a) is a wide angle end, (b) is an intermediate, and (c). Indicates the state at the telephoto end. (A) of the zoom lens according to Example 7 of the present invention is a cross-sectional view along the optical axis showing an optical configuration at the time of focusing on an object point at infinity at the wide-angle end, (b) at the middle, and (c) at the telephoto end. is there. FIG. 9 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 7 is focused on an object point at infinity, where (a) is a wide angle end, (b) is an intermediate, and (c). Indicates the state at the telephoto end. (A) of the zoom lens according to Example 8 of the present invention is a cross-sectional view along the optical axis showing an optical configuration at the time of focusing on an object point at infinity at the wide-angle end, (b) at the middle, and (c) at the telephoto end. is there. FIG. 10 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 8 is focused on an object point at infinity, where (a) is a wide angle end, (b) is an intermediate, and (c). Indicates the state at the telephoto end. (A) of the zoom lens according to Example 9 of the present invention is a cross-sectional view along the optical axis showing an optical configuration at the time of focusing on an object point at infinity at the wide-angle end, (b) at the middle, and (c) at the telephoto end. is there. FIG. 10 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 9 is focused on an object point at infinity, where (a) is a wide-angle end, (b) is an intermediate, and (c). Indicates the state at the telephoto end. It is a front perspective view which shows the external appearance of the digital camera 40 incorporating the zoom optical system by this invention. 2 is a rear perspective view of the digital camera 40. FIG. 2 is a cross-sectional view showing an optical configuration of a digital camera 40. 1 is a front perspective view of a state in which a cover of a personal computer 300 which is an example of an information processing apparatus in which a zoom optical system of the present invention is built as an objective optical system is opened. FIG. 2 is a cross-sectional view of a photographing optical system 303 of a personal computer 300. FIG. 2 is a side view of a personal computer 300. FIG. 1A and 1B are views showing a mobile phone as an example of an information processing apparatus in which the zoom optical system of the present invention is built in as a photographing optical system, where FIG. 1A is a front view of the mobile phone 400, FIG. FIG. 6 is a cross-sectional view of the photographing optical system 405.

  Embodiments in which the imaging optical system according to the present invention is applied to a zoom optical system will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Prior to the description of the examples, the effects of the imaging optical system of the present embodiment will be described. In the following description, the positions and intervals of the lens groups are in the optical axis direction. Further, the position of the lens group can be specified with reference to the image plane, for example.

The imaging optical system of the present embodiment includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a final lens group. The first lens group includes only one cemented lens component, and the cemented lens component is formed by cementing one negative lens and two positive lenses, and satisfies the following conditional expression (1) It is characterized by.
0.05 <ΔD12 / ((ΣD1 + ΣD2) × γ × tan ω) <0.19 (1)
here,
ΔD12 is represented by | D12T-D12W |
D12W is the distance between the first lens group and the second lens group at the wide-angle end,
D12T is the distance between the first lens group and the second lens group at the telephoto end,
ΣD1 is the thickness of the first lens group,
ΣD2 is the thickness of the second lens group,
γ is the zoom ratio from the wide-angle end to the telephoto end of the imaging optical system,
ω is the maximum angle of view,
It is.

  The first lens group greatly contributes to correction of chromatic aberration, particularly on the telephoto side. For this reason, if a cemented lens is disposed for the purpose of satisfactorily correcting chromatic aberration, the thickness of the first lens group tends to be thick. Therefore, in the present embodiment, the first lens group is made up of only one cemented lens component. In this cemented lens component, one negative lens and two positive lenses are cemented together. As described above, in the imaging optics of the present embodiment, the first lens group has the minimum configuration necessary to reduce the total length of the lens group while correcting chromatic aberration.

  In the second lens group, astigmatism and coma aberration can be favorably corrected when the distance between the negative lens and the positive lens in the second lens group is generally wider. However, if the distance between the negative lens and the positive lens in the second lens group is increased, the thickness of the second lens group is increased, and the total length of the optical system and the retracted thickness cannot be shortened.

  In an optical system with a large zoom ratio, the lens group responsible for zooming generally moves greatly from the wide-angle end to the telephoto end, so that the total length of the optical system tends to be long. Further, in an optical system having a large maximum angle of view ω, that is, an optical system having a wide angle of view at a wide angle, the focal length of the entire optical system becomes short. In such an optical system, the power of the first lens group is increased. Therefore, the curvature of the positive lens in the first lens group is increased. Here, in order to prevent the border of the positive lens from becoming too thin, the thickness of the medium is increased. Furthermore, if a plurality of positive lenses are arranged in the first lens group so that the curvature of the positive lens does not become too large, the thickness of the first lens group becomes thick. Therefore, it becomes impossible to shorten the total length of the optical system and the collapsed thickness.

  The imaging optical system of the present embodiment is characterized by satisfying conditional expression (1). Therefore, the fluctuation amount ΔD12 is smaller than ΣD1 and ΣD2. Further, even when the zoom ratio is large, the variation ΔD12 is small, and even when the maximum angle of view ω is large, the variation ΔD12 is small. This realizes an optical system in which the amount of variation ΔD12 is small and the total length of the optical system and the collapsed thickness are short while suppressing chromatic aberration satisfactorily.

  If the upper limit value of conditional expression (1) is exceeded, the fluctuation amount ΔD12 increases. In this case, the total length at the telephoto end cannot be shortened. Alternatively, ΣD1 + ΣD2 becomes smaller. As described above, the first lens group has the minimum configuration necessary for making the first lens group thinner while correcting chromatic aberration. That is, since ΣD1 cannot be reduced, ΣD2 is reduced. Then, since the distance between the lenses in the second lens group becomes narrow, astigmatism and coma cannot be corrected well. Such a problem becomes prominent when the fluctuation amount ΔD12 is kept small.

  If the lower limit of conditional expression (1) is not reached, the fluctuation amount ΔD12 becomes too small. For this reason, the zoom ratio becomes small. Also, ΣD1 + ΣD2 increases. For this reason, the collapsed thickness cannot be shortened.

Further, it is more preferable that the conditional expression (1 ′) is satisfied instead of the conditional expression (1).
0.1 <ΔD12 / ((ΣD1 + ΣD2) × γ × tan ω) <0.18 (1 ′)
When the conditional expression (1 ′) is satisfied, the retractable thickness can be reduced while further correcting astigmatism and coma.

  As described above, when the conditional expression (1) or the conditional expression (1 ′) is satisfied, the total length of the optical system and the retractable thickness can be shortened without deteriorating astigmatism and coma in addition to chromatic aberration. As a result, a thin camera capable of obtaining a high-quality image can be obtained.

Moreover, it is preferable that the imaging optical system of this embodiment satisfies the following conditional expression (2).
-0.8 <ΔV2 / ΔV1 <0.8 (2)
here,
ΔV1 is represented by | V1W-V1T |
V1W is the position of the first lens group at the wide-angle end,
V1T is the position of the first lens group at the telephoto end,
ΔV2 is represented by | V2W-V2T |
V2W is the position of the second lens group at the wide-angle end,
V2T is the position of the second lens group at the telephoto end,
The sign is positive when each lens group is located on the object side at the telephoto end with respect to the position at the wide-angle end.

  When the conditional expression (2) is satisfied, ΔV2 becomes smaller than ΔV1. At this time, the second lens group position does not change much between the wide-angle end and the telephoto end. For this reason, when the conditional expression (2) is satisfied, the total length of the optical system at the wide-angle end can be shortened.

  If the upper limit of conditional expression (2) is exceeded, the positions of the first lens group and the second lens group at the telephoto end are both closer to the object side than the position at the wide-angle end. Further, the amount by which the second lens group moves toward the object side increases. In this case, the distance between the first lens group and the second lens group does not change much between the wide-angle end and the telephoto end, so that the zoom ratio cannot be increased.

  Below the lower limit of conditional expression (2), the position of the second lens group at the telephoto end is closer to the image side than the position at the wide-angle end, and the amount by which the second lens group moves toward the image side is large. Become. In this case, since the negative power of the second lens group is reduced, the ray height of off-axis rays in the second lens group is increased. Therefore, off-axis aberrations such as coma become large.

Further, it is more preferable that the conditional expression (2 ′) is satisfied instead of the conditional expression (2).
-0.5 <ΔV2 / ΔV1 <0.5 (2 ')
When the conditional expression (2 ′) is satisfied, it is possible to further shorten the total length of the optical system at the wide-angle end while increasing the zoom ratio and suppressing the occurrence of coma and off-axis aberrations.

  As described above, when the conditional expression (2) or the conditional expression (2 ′) is satisfied, the total length of the optical system at the wide angle end is increased in addition to increasing the zoom ratio while keeping off-axis aberrations such as coma aberration small. Can be shortened. As a result, a thin camera capable of obtaining a high-quality image can be obtained.

Moreover, it is preferable that the imaging optical system of this embodiment satisfies the following conditional expression (3).
-0.3 <ΔVL / fw <0.6 (3)
here,
ΔVL is represented by | V2W-V2T |
VLW is the position of the last lens group at the wide-angle end,
VLT is the position of the last lens group at the telephoto end.
fw is the focal length of the entire imaging optical system at the wide-angle end,
The sign is positive when the last lens group is located on the object side at the telephoto end with respect to the position at the wide-angle end.

  When the conditional expression (3) is satisfied, the position of the final lens group does not change much at the wide-angle end and the telephoto end. Then, the variation in field curvature at the wide-angle end and the telephoto end is also reduced. Thereby, the fluctuation | variation of the field curvature by zooming can be suppressed small. As a result, the influence of the curvature of field is small at the wide-angle end and the telephoto end, and a high-quality image in focus can be obtained on the entire screen.

  If the upper limit value of conditional expression (3) is exceeded, the position of the final lens group at the telephoto end greatly moves toward the object side with respect to the wide-angle end, so that the variation in field curvature increases. If the lower limit value of conditional expression (3) is not reached, the position of the final lens group at the telephoto end moves greatly toward the image side with respect to the wide-angle end, and the variation in field curvature increases.

  In addition, elements such as an infrared cut filter, a low-pass filter, and an image sensor are disposed on the image side of the final lens group. Therefore, if the lower limit value of conditional expression (3) is not reached, there is a problem that the distance between the last lens group and these elements becomes narrow at the telephoto end, or a space for arranging these elements cannot be secured. . In particular, when the final lens group is a focus group, a space for moving the final lens group cannot be secured during the focusing operation, and there is a case where the final lens group cannot be focused.

It is more preferable that the conditional expression (3 ′) is satisfied instead of the conditional expression (3).
-0.2 <ΔVL / fw <0.4 (3 ′)
When the conditional expression (3 ′) is satisfied, it is possible to further suppress the influence of the field curvature at both the wide angle end and the telephoto end.

  As described above, if the conditional expression (3) or the conditional expression (3 ′) is satisfied, a thin camera that can suppress a change in field curvature due to zooming and obtain a high-quality image at both the wide-angle end and the telephoto end. Can be obtained.

  In the imaging optical system of this embodiment, it is preferable that at least one cemented surface of the cemented lens component is an aspheric surface.

  The off-axis light beam that forms an image at a high image height enters the first lens group at a position where the light beam height is high (a position away from the optical axis on the lens surface). Therefore, if the cemented surface of the cemented lens component is an aspherical surface, off-axis aberrations, particularly chromatic aberration of magnification, which is off-axis chromatic aberration, can be corrected well. Accordingly, it is possible to obtain a thin camera that can correct off-axis aberrations, particularly chromatic aberration of magnification, and obtain a high-quality image even around the image.

  In the imaging optical system of the present embodiment, it is preferable that the two positive lenses in the cemented lens component are arranged adjacent to each other, and the cemented surface of the two positive lenses is an aspherical surface.

  By arranging two positive lenses next to each other, chromatic aberration can be corrected by the difference in Abbe number of the two positive lenses. Further, when the cemented surface is an aspheric surface, particularly off-axis chromatic aberration, that is, chromatic aberration of magnification can be corrected well. Therefore, it is possible to obtain a thin camera that can correct chromatic aberration of magnification well and obtain a high-quality image even around the image.

Moreover, it is preferable that the imaging optical system of this embodiment satisfies the following conditional expression (4).
0.0005 <| (P0−Ph) / P0 | <0.3 (4)
here,
P0 is the power on the optical axis of the joint surface,
Ph is the local power at the beam height h of the joint surface,
The ray height h is the ray height at which the absolute value of the difference between the local power of the joint surface and the power on the optical axis is maximized.

  The first lens group has a relatively large amount of movement in the optical axis direction during zooming. In addition, the state of the light flux of each image height incident on the first lens group (incident angle, light beam diameter, etc.) also changes greatly with zooming. Therefore, when the shape of the cemented surface of the first lens group is an aspherical shape in which the local power changes extremely within the effective diameter, the aberration varies greatly from the wide-angle end to the telephoto end. End up. For this reason, it is difficult to satisfactorily correct aberrations at both the wide-angle end and the telephoto end.

  When the conditional expression (4) is satisfied, the joint surface has a shape in which the local power of the joint surface does not change extremely within the effective diameter. Therefore, it is possible to suppress aberration fluctuations due to zooming and correct aberrations well at both the wide-angle end and the telephoto end.

  If the upper limit value of conditional expression (4) is exceeded, the difference between the power on the optical axis of the cemented surface and the local power at the light beam height h becomes too large, so that the variation in aberration due to zooming is large. turn into. If the lower limit of conditional expression (4) is not reached, the difference between the power on the optical axis and the local power becomes too small even at the beam height h where the difference from the power on the optical axis is maximum. End up. For this reason, it becomes impossible to correct off-axis aberrations due to the aspherical surface, particularly chromatic aberration of magnification.

It is more preferable that conditional expression (4 ′) is satisfied instead of conditional expression (4).
0.001 <| (P0−Ph) / P0 | <0.2 (4 ′)
When the conditional expression (4 ′) is satisfied, the aberration can be corrected satisfactorily at both the wide-angle end and the telephoto end.

  As described above, when the conditional expression (4) or the conditional expression (4 ′) is satisfied, it is possible to suppress the occurrence of off-axis aberration and to suppress the fluctuation of aberration due to zooming. However, a thin camera that can obtain high-quality images can be obtained.

In the imaging optical system of the present embodiment, it is preferable that the third lens group has only two components, a positive component lens and a negative component lens, and the negative component lens satisfies the conditional expression (5). .
2 <SF3 <10 (5)
here,
SF3 is a shaping factor of the negative component lens of the third lens group, and the shaping factor is a value defined by the following equation:
SF3 = (r31 + r32) / (r31-r32)
r31 is the radius of curvature of the object side surface of the negative component lens of the third lens group;
r32 is the radius of curvature of the image side surface of the negative lens component of the third lens group;
It is.
It is more preferable that each of the positive component lens and the negative component lens is a single lens, and the third lens group is configured by only two single lenses of the positive lens and the negative lens.

  When the conditional expression (5) is satisfied, the negative power on the image side surface of the negative component lens increases. Then, the principal point of the negative component lens moves closer to the image side, and the positive component lens and the negative component lens of the third lens unit can be brought closer without changing the focal length of the third lens unit. Thus, since the thickness of the third lens group can be reduced, the overall length of the optical system can also be shortened. At the same time, since the principal point of the third lens group approaches the object side, the distance from the principal point of the second lens group is shortened. As a result, the overall length of the optical system can be further shortened.

  If the upper limit value of conditional expression (5) is exceeded, the negative power on the image side surface of the negative component lens becomes too strong. In this case, fluctuations in various aberrations such as astigmatism and distortion occurring on the image side surface of the negative component lens become large, which is not preferable in terms of aberration correction. If the lower limit value of conditional expression (5) is not reached, the distance between the positive component lens and the negative component lens of the third lens group is widened. In this case, since the thickness of the third lens group is increased, the entire length of the optical system is also increased.

Further, it is more preferable that the conditional expression (5 ′) is satisfied instead of the conditional expression (5).
3 <SF3 <7 (5 ')
When the conditional expression (5 ′) is satisfied, the thickness of the third lens group can be further reduced, and the total length of the optical system can be further reduced.
Further, instead of conditional expression (5), (5 ″) may be satisfied.
3 <SF3 <10 (5 '')

  As described above, when the conditional expression (5) or the conditional expression (5 ′) is satisfied, the thickness of the third lens unit and the total length of the optical system can be shortened while satisfactorily suppressing the fluctuation of aberration, and a high-quality image can be obtained. An obtained thin camera can be obtained.

In the imaging optical system of the present embodiment, it is preferable that the final lens group includes one positive lens, and the positive lens satisfies the conditional expression (6).
-5 <SFL <0 (6)
here,
SFL is the shaping factor of the positive lens in the final lens group, and the shaping factor is a value defined by the following equation:
SFL = (rL1 + rL2) / (rL1-rL2))
rL1 is the radius of curvature of the object side surface of the positive lens in the final lens group,
rL2 is the radius of curvature of the image side surface of the positive lens in the final lens group,
It is.

  When the conditional expression (6) is satisfied, the positive power on the object side of the positive lens becomes large, so that the principal point of the positive lens moves closer to the object side. Then, the distance between the principal point of the final lens group and the principal point of the adjacent lens group on the object side of the final lens group is shortened, so that the overall length of the optical system can be shortened.

  If the upper limit value of conditional expression (6) is exceeded, the positive power on the object side surface of the positive lens becomes too strong, and various aberrations such as astigmatism and coma occur. If the lower limit value of conditional expression (6) is not reached, the principal point of the positive lens is closer to the image side, so the distance between the principal point of the adjacent lens group on the object side is longer than the final lens group. As a result, the total length of the optical system becomes long.

Further, it is more preferable that the conditional expression (6 ′) is satisfied instead of the conditional expression (6).
-3 <SFL <-1 (6 ')
When the conditional expression (6 ′) is satisfied, the total length of the optical system can be further shortened.

  As described above, when conditional expression (6) or conditional expression (6 ′) is satisfied, the total length of the optical system can be shortened while satisfactorily suppressing aberrations, and a thin camera capable of obtaining high-quality images can be obtained.

In the imaging optical system of the present embodiment, it is preferable that the cemented lens component satisfies the conditional expression (7).
2 <f1T1 / f1 <15 (7)
here,
f1 is the focal length of the entire cemented lens component,
f1T1 is the focal length of the positive lens located on the object side, out of the two positive lenses included in the cemented lens component,
It is.

  In the imaging optical system according to the present embodiment, the first lens group includes only a cemented lens component. For this reason, primary chromatic aberration cannot be completely corrected only within the first lens group. However, if there are many primary chromatic aberrations, fluctuations in chromatic aberration due to zooming cannot be suppressed. Therefore, by reducing the power of the positive lens on the object side to such an extent that the conditional expression (7) is satisfied, the primary chromatic aberration is corrected as much as possible, and the correction of the secondary spectrum is also performed so that both aberrations can be corrected. be able to.

  When the conditional expression (7) is satisfied, the focal length of the positive lens on the object side becomes longer than the focal length of the cemented lens component. That is, since the power of the positive lens on the object side becomes weak, primary chromatic aberration can be corrected well. If the power of the positive lens on the object side is increased, the secondary spectrum can be easily corrected, but the primary chromatic aberration cannot be corrected.

  If the upper limit value of conditional expression (7) is exceeded, the power of the positive lens on the object side becomes too weak, and the secondary spectrum cannot be corrected well. If the lower limit of conditional expression (7) is not reached, the power of the positive lens on the object side becomes too strong, so that the primary chromatic aberration cannot be kept small in the first lens group.

More preferably, the imaging optical system of the present embodiment satisfies the conditional expression (7 ′).
3 <f1T1 / f1 <10 (7 ')
When the conditional expression (7 ′) is satisfied, the secondary spectrum and the primary chromatic aberration can be corrected satisfactorily.

  As described above, when the conditional expression (7) or the conditional expression (7 ′) is satisfied, the generation of the secondary spectrum can be suppressed while satisfactorily suppressing the primary chromatic aberration at the wide-angle end and the telephoto end. As a result, a thin camera capable of obtaining a high-quality image can be obtained.

Moreover, it is preferable that the imaging optical system of this embodiment satisfies the following conditional expression (8).
0.60 <θgFT1 <0.80 (8)
here,
θgFT1 is the partial dispersion ratio (ngT1−nFT1) / (nFT1−nCT1) of the positive lens located on the object side of the two positive lenses included in the cemented lens component,
nCT1, nFT1, and ngT1 are refractive indexes of the C-line, F-line, and g-line of the positive lens located on the object side,
It is.

  In general, in the correction of chromatic aberration, a high dispersion material is used for the negative lens. Here, since the partial dispersion ratio θgF of the high dispersion material is large, the partial dispersion ratio θgF of the negative lens is also large. Therefore, even if the chromatic aberration can be corrected between the two wavelengths of the C line and the F line, the residual chromatic aberration tends to be large at other wavelengths, so that a large secondary spectrum is generated. Therefore, even in the first lens group, the generation of the secondary spectrum becomes a problem.

  When the conditional expression (8) is satisfied, the positive lens located on the object side has a large partial dispersion ratio θgF1T. Then, the combined partial dispersion ratio θgF of the negative lens and the positive lens in the cemented lens component (in the first lens group) is substantially lower than the partial dispersion ratio θgF of the negative lens. Therefore, generation of a secondary spectrum can be suppressed.

  If the upper limit of conditional expression (8) is exceeded, the partial dispersion ratio θgF of the synthesis will be too low. Therefore, the difference from the partial dispersion ratio of the positive lens on the image side in the first lens group becomes small, and chromatic aberration at a short wavelength cannot be corrected well. If the lower limit of conditional expression (8) is not reached, the combined partial dispersion ratio θgF will not be so low, and the generation of the secondary spectrum will not be suppressed.

It is more preferable that the conditional expression (8 ′) is satisfied instead of the conditional expression (8).
0.62 <θgFT1 <0.75 (8 ')
When the conditional expression (8 ′) is satisfied, it is possible to further suppress the occurrence of chromatic aberration and a secondary spectrum at a short wavelength.

  As described above, when the conditional expression (8) is satisfied, a thin camera capable of satisfactorily correcting chromatic aberration at a short wavelength while suppressing generation of a secondary spectrum and obtaining a high-quality image. Can be obtained.

  In addition, an electronic imaging apparatus according to the present embodiment includes the above-described imaging optical system and an electronic imaging element. The imaging optical system described above can shorten the entire length of the optical system and the collapsed thickness without deteriorating chromatic aberration and the like. Therefore, when such an imaging optical system is used for an electronic imaging device, it is possible to obtain a thinned electronic imaging device while obtaining a high-quality image.

  By the way, when coma and astigmatism are corrected over a wide angle of view, strong barrel distortion occurs on the wide angle side. On the other hand, when the barrel distortion is corrected, coma and astigmatism at a large angle of view are deteriorated.

  Therefore, a method for realizing a wider angle of view by actively utilizing the occurrence of barrel distortion will be described below. When this method is used, the conditional expressions described so far are easily satisfied.

First, suppose that an object at infinity is imaged by an optical system without distortion. In this case, since the image formed has no distortion,
f = y / tan ω (15)
Is established.
here,
y is the height of the image point from the optical axis,
f is the focal length of the imaging system,
ω is an angle with respect to the optical axis in the object direction corresponding to the image point connected from the center on the imaging surface to the position y.

On the other hand, if the optical system has barrel distortion,
f> y / tan ω (16)
It becomes. That is, if f and y are constant values, ω is a large value.

  Therefore, it is preferable to use an optical system that intentionally has a large barrel distortion, particularly at a focal length near the wide-angle end, for the electronic imaging device. In this case, it is possible to achieve a wider angle of view of the optical system as much as it is not necessary to correct distortion.

  However, the image of the object is formed on the electronic image pickup device in a state having barrel-shaped distortion. Therefore, in the electronic imaging device, image data obtained by the electronic imaging element is processed by image processing. In this processing, the image data (image shape) is changed so as to correct the barrel distortion.

  In this way, the finally obtained image data is image data having a shape substantially similar to the object. Therefore, an object image may be output to a CRT or printer based on the image data.

  In the distortion diagrams in the following examples, the image height at the wide-angle end is smaller than the image height at the intermediate position and the telephoto end. In such a case, by performing the above-described image processing, distortion aberration is corrected, and a subject image having the same image height as the intermediate position or the telephoto end can be obtained. In the numerical data and aberration diagrams of the following examples, the image height at the wide-angle end differs between the numerical data and the aberration diagrams. This is because the image height of the aberration diagram represents the image height before the above image processing (image height formed by the optical system), while the image height of the numerical data performs the above image processing. This is because it represents the image height after.

  Embodiments of an imaging optical system and an electronic imaging device 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.

  Next, a zoom lens (imaging optical system) according to Example 1 of the invention will be described. FIGS. 1A and 1B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to the first embodiment of the present invention when focusing on an object point at infinity. FIG. 1A is a wide-angle end, and FIG. (C) is a sectional view at the telephoto end.

  FIG. 2 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when the zoom lens according to Example 1 is focused on an object point at infinity. a) shows the wide-angle end, (b) shows the intermediate focal length state, and (c) shows the state at the telephoto end. FIY represents the image height. The symbols in the aberration diagrams are the same in the examples described later.

  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 positive refractive power, a second lens group G2 having a negative refractive power, and an aperture stop S. And a third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power. In all the following examples, in the lens cross-sectional views, LPF is a low-pass filter, CG is a cover glass, and I is an image pickup surface of an electronic image pickup element.

  The first lens group G1 includes a cemented lens of a negative meniscus lens L1 having a convex surface facing the object side, a positive meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side. And has a positive refractive power as a whole.

  The second lens group G2 includes a negative meniscus lens L4 having a convex surface facing the object side, a biconcave negative lens L5, and a positive meniscus lens L6 having a convex surface facing the object side. Has refractive power.

  The third lens group G3 includes a positive biconvex lens L7 and a negative meniscus lens L8 having a convex surface directed toward the object side, and has a positive refracting power as a whole.

  The fourth lens group G4 includes a positive meniscus lens L9 having a convex surface directed toward the object side, and has a positive refracting power as a whole.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the object side, then moves to the image side, and the third lens group After moving to the object side, the fourth lens group G4 moves to the image side after moving to the object side.

  The aspherical surfaces include both surfaces of the positive meniscus lens L3 in the first lens group G1, both surfaces of the biconcave negative lens L5 in the second lens group G2, and both surfaces of the biconvex positive lens L7 in the third lens group G3. It is provided on eight surfaces including the image side surface of the negative meniscus lens L8 and the object side surface of the positive meniscus lens L9 in the fourth lens group G4.

  Next, a zoom lens (imaging optical system) according to Embodiment 2 of the present invention will be described. FIGS. 3A and 3B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to the second embodiment of the present invention when focusing on an object point at infinity, where FIG. 3A is a wide-angle end, and FIG. (C) is a sectional view at the telephoto end.

  FIG. 4 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when the zoom lens according to Example 2 is focused on an object point at infinity. a) shows the wide-angle end, (b) shows the intermediate focal length state, and (c) shows the state at the telephoto end.

  As shown in FIG. 3, the zoom lens of Example 2 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and an aperture stop S. And a third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes a cemented lens of a negative meniscus lens L1 having a convex surface facing the object side, a positive meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side. And has a positive refractive power as a whole.

  The second lens group G2 includes a negative meniscus lens L4 having a convex surface facing the object side, a biconcave negative lens L5, and a positive meniscus lens L6 having a convex surface facing the object side. Has refractive power.

  The third lens group G3 includes a biconvex positive lens L7 and a negative meniscus lens L8 having a convex surface directed toward the object side, and has a positive refractive power as a whole.

  The fourth lens group G4 includes a positive meniscus lens L9 having a convex surface directed toward the object side, and has a positive refracting power as a whole.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the object side, After moving to the object side, the fourth lens group moves to the image side.

  The aspherical surfaces include both surfaces of the positive meniscus lens L3 in the first lens group G1, both surfaces of the biconcave negative lens L5 in the second lens group G2, and both surfaces of the biconvex positive lens L7 in the third lens group G3. It is provided on eight surfaces including the image side surface of the negative meniscus lens L8 and the object side surface of the positive meniscus lens L9 in the fourth lens group G4.

  Next, a zoom lens (imaging optical system) according to Embodiment 3 of the present invention will be described. FIGS. 5A and 5B are cross-sectional views along the optical axis showing an optical configuration when focusing on an object point at infinity of a zoom lens according to Example 3 of the present invention, where FIG. 5A is a wide angle end, and FIG. 5B is an intermediate focal length state. (C) is a sectional view at the telephoto end.

  FIG. 6 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when the zoom lens according to Example 3 is focused on an object point at infinity. a) shows the wide-angle end, (b) shows the intermediate focal length state, and (c) shows the state at the telephoto end.

  As shown in FIG. 5, the zoom lens of Example 3 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and an aperture stop S. And a third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes a cemented lens of a negative meniscus lens L1 having a convex surface facing the object side, a positive meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side. And has a positive refractive power as a whole.

  The second lens group G2 includes a negative meniscus lens L4 having a convex surface facing the object side, a biconcave negative lens L5, and a positive meniscus lens L6 having a convex surface facing the object side. Has refractive power.

  The third lens group G3 includes a biconvex positive lens L7 and a negative meniscus lens L8 having a convex surface directed toward the object side, and has a positive refractive power as a whole.

  The fourth lens group G4 includes a positive meniscus lens L9 having a convex surface directed toward the object side, and has a positive refracting power as a whole.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the object side, then moves to the image side, and the third lens group G3 Moves to the object side, and the fourth lens group moves to the image side after moving to the object side.

  The aspherical surfaces include both surfaces of the positive meniscus lens L3 in the first lens group G1, both surfaces of the biconcave negative lens L5 in the second lens group G2, and both surfaces of the biconvex positive lens L7 in the third lens group G3. It is provided on eight surfaces including the image side surface of the negative meniscus lens L8 and the object side surface of the positive meniscus lens L9 in the fourth lens group G4.

  Next, a zoom lens (imaging optical system) according to Embodiment 4 of the present invention will be described. FIGS. 7A and 7B are cross-sectional views along the optical axis showing the optical configuration when focusing on an object point at infinity of a zoom lens according to Example 4 of the present invention, where FIG. 7A is a wide angle end, and FIG. 7B is an intermediate focal length state. (C) is a sectional view at the telephoto end.

  FIG. 8 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when the zoom lens according to Example 4 is focused on an object point at infinity. a) shows the wide-angle end, (b) shows the intermediate focal length state, and (c) shows the state at the telephoto end.

  As shown in FIG. 7, the zoom lens of Example 4 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and an aperture stop S. And a third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes a cemented lens of a negative meniscus lens L1 having a convex surface facing the object side, a positive meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side. And has a positive refractive power as a whole.

  The second lens group G2 includes a negative meniscus lens L4 having a convex surface facing the object side, a biconcave negative lens L5, and a positive meniscus lens L6 having a convex surface facing the object side. Has refractive power.

  The third lens group G3 includes a biconvex positive lens L7 and a negative meniscus lens L8 having a convex surface directed toward the object side, and has a positive refractive power as a whole.

  The fourth lens group G4 includes a positive meniscus lens L9 having a convex surface directed toward the object side, and has a positive refracting power as a whole.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. After moving to the object side, the fourth lens group moves to the image side.

  The aspherical surfaces include both surfaces of the positive meniscus lens L3 in the first lens group G1, both surfaces of the biconcave negative lens L5 in the second lens group G2, and both surfaces of the biconvex positive lens L7 in the third lens group G3. It is provided on eight surfaces including the image side surface of the negative meniscus lens L8 and the object side surface of the positive meniscus lens L9 in the fourth lens group G4.

  Next, a zoom lens (imaging optical system) according to Embodiment 5 of the present invention will be described. 9A and 9B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to Example 5 of the present invention when focusing on an object point at infinity, where FIG. 9A is a wide-angle end, and FIG. 9B is an intermediate focal length state. (C) is a sectional view at the telephoto end.

  FIG. 10 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when the zoom lens according to Example 5 is focused on an object point at infinity. a) shows the wide-angle end, (b) shows the intermediate focal length state, and (c) shows the state at the telephoto end.

  As shown in FIG. 9, the zoom lens of Example 5 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and an aperture stop S. And a third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes a cemented lens of a negative meniscus lens L1 having a convex surface facing the object side, a positive meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side. And has a positive refractive power as a whole.

  The second lens group G2 includes a negative meniscus lens L4 having a convex surface facing the object side, a biconcave negative lens L5, and a positive meniscus lens L6 having a convex surface facing the object side. Has refractive power.

  The third lens group G3 includes a biconvex positive lens L7 and a negative meniscus lens L8 having a convex surface directed toward the object side, and has a positive refractive power as a whole.

  The fourth lens group G4 includes a positive meniscus lens L9 having a convex surface directed toward the object side, and has a positive refracting power as a whole.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. After moving to the object side, the fourth lens group moves to the image side.

  The aspherical surfaces are the image-side surface of the negative meniscus lens L1 in the first lens group G1, both surfaces of the positive meniscus lens L3, both surfaces of the biconcave negative lens L5 in the second lens group G2, and the third lens group. It is provided on nine surfaces including both surfaces of the biconvex positive lens L7 in G3, the image side surface of the negative meniscus lens L8, and the object side surface of the positive meniscus lens L9 in the fourth lens group G4.

  Next, a zoom lens (imaging optical system) according to Embodiment 6 of the present invention will be described. 11A and 11B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to Example 6 of the present invention when focusing on an object point at infinity. FIG. 11A is a wide angle end, and FIG. 11B is an intermediate focal length state. (C) is a sectional view at the telephoto end.

  FIG. 12 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when the zoom lens according to Example 6 is focused on an object point at infinity. a) shows the wide-angle end, (b) shows the intermediate focal length state, and (c) shows the state at the telephoto end.

  As shown in FIG. 11, the zoom lens of Example 6 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and an aperture stop S. And a third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes a cemented lens of a negative meniscus lens L1 having a convex surface facing the object side, a positive meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side. And has a positive refractive power as a whole.

  The second lens group G2 includes a negative meniscus lens L4 having a convex surface facing the object side, a biconcave negative lens L5, and a positive meniscus lens L6 having a convex surface facing the object side. Has refractive power.

  The third lens group G3 includes a biconvex positive lens L7 and a negative meniscus lens L8 having a convex surface directed toward the object side, and has a positive refractive power as a whole.

  The fourth lens group G4 includes a positive meniscus lens L9 having a convex surface directed toward the object side, and has a positive refracting power as a whole.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. After moving to the object side, the fourth lens group moves to the image side.

  The aspheric surfaces are both surfaces of the positive meniscus lens L3 in the first lens group G1, both surfaces of the biconcave negative lens L5 in the second lens group G2, and both surfaces of the biconvex positive lens L7 in the third lens group G3. The image surface of the negative meniscus lens L8 and the object side surface of the positive meniscus lens L9 in the fourth lens group G4 are provided on eight surfaces.

  Next, a zoom lens (imaging optical system) according to Embodiment 7 of the present invention will be described. FIGS. 13A and 13B are cross-sectional views along the optical axis showing the optical configuration when focusing on an object point at infinity of a zoom lens according to Example 7 of the present invention. FIG. 13A is a wide-angle end, and FIG. 13B is an intermediate focal length state. (C) is a sectional view at the telephoto end.

  FIG. 14 is a diagram showing spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when the zoom lens according to Example 7 is focused on an object point at infinity. a) shows the wide-angle end, (b) shows the intermediate focal length state, and (c) shows the state at the telephoto end.

  As shown in FIG. 13, the zoom lens of Example 7 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and an aperture stop S. And a third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes a cemented lens of a negative meniscus lens L1 having a convex surface facing the object side, a positive meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side. And has a positive refractive power as a whole.

  The second lens group G2 includes a negative meniscus lens L4 having a convex surface facing the object side, a biconcave negative lens L5, and a positive meniscus lens L6 having a convex surface facing the object side. Has refractive power.

  The third lens group G3 includes a biconvex positive lens L7 and a negative meniscus lens L8 having a convex surface directed toward the object side, and has a positive refractive power as a whole.

  The fourth lens group G4 includes a positive meniscus lens L9 having a convex surface directed toward the object side, and has a positive refracting power as a whole.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. After moving to the object side, the fourth lens group moves to the image side.

  The aspheric surfaces are both surfaces of the positive meniscus lens L3 in the first lens group G1, both surfaces of the biconcave negative lens L5 in the second lens group G2, and both surfaces of the biconvex positive lens L7 in the third lens group G3. The image surface of the negative meniscus lens L8 and the object side surface of the positive meniscus lens L9 in the fourth lens group G4 are provided on eight surfaces.

  Next, a zoom lens (imaging optical system) according to Embodiment 8 of the present invention will be described. 15A and 15B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to Example 8 of the present invention when focusing on an object point at infinity, where FIG. 15A is a wide angle end, and FIG. 15B is an intermediate focal length state. (C) is a sectional view at the telephoto end.

  FIG. 16 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when the zoom lens according to Example 8 is focused on an object point at infinity. a) shows the wide-angle end, (b) shows the intermediate focal length state, and (c) shows the state at the telephoto end.

  As shown in FIG. 15, the zoom lens according to the eighth embodiment includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and an aperture stop S. And a third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes a cemented lens of a negative meniscus lens L1 having a convex surface facing the object side, a positive meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side. And has a positive refractive power as a whole.

  The second lens group G2 includes a negative meniscus lens L4 having a convex surface facing the object side, a biconcave negative lens L5, and a positive meniscus lens L6 having a convex surface facing the object side. Has refractive power.

  The third lens group G3 includes a biconvex positive lens L7 and a negative meniscus lens L8 having a convex surface directed toward the object side, and has a positive refractive power as a whole.

  The fourth lens group G4 includes a positive meniscus lens L9 having a convex surface directed toward the object side, and has a positive refracting power as a whole.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. After moving to the object side, the fourth lens group moves to the image side.

  The aspherical surfaces are the image-side surface of the negative meniscus lens L1 in the first lens group G1, both surfaces of the positive meniscus lens L3, both surfaces of the biconcave negative lens L5 in the second lens group G2, and the third lens group. It is provided on nine surfaces including both surfaces of the biconvex positive lens L7 in G3, the image side surface of the negative meniscus lens L8, and the object side surface of the positive meniscus lens L9 in the fourth lens group G4.

  Next, a zoom lens (imaging optical system) according to Embodiment 9 of the present invention will be described. FIGS. 17A and 17B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to Example 9 of the present invention when focusing on an object point at infinity, where FIG. 17A is a wide-angle end, and FIG. (C) is a sectional view at the telephoto end.

  FIG. 18 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when the zoom lens according to Example 9 is focused on an object point at infinity. a) shows the wide-angle end, (b) shows the intermediate focal length state, and (c) shows the state at the telephoto end.

  As shown in FIG. 17, the zoom lens of Example 9 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and an aperture stop S. And a third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes a cemented lens of a negative meniscus lens L1 having a convex surface facing the object side, a positive meniscus lens L2 having a convex surface facing the object side, and a positive meniscus lens L3 having a convex surface facing the object side. And has a positive refractive power as a whole.

  The second lens group G2 includes a negative meniscus lens L4 having a convex surface facing the object side, a biconcave negative lens L5, and a positive meniscus lens L6 having a convex surface facing the object side. Has refractive power.

  The third lens group G3 includes a biconvex positive lens L7 and a negative meniscus lens L8 having a convex surface directed toward the object side, and has a positive refractive power as a whole.

  The fourth lens group G4 includes a positive meniscus lens L9 having a convex surface directed toward the object side, and has a positive refracting power as a whole.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. After moving to the object side, the fourth lens group moves to the image side.

  The aspheric surfaces are both surfaces of the positive meniscus lens L3 in the first lens group G1, both surfaces of the biconcave negative lens L5 in the second lens group G2, and both surfaces of the biconvex positive lens L7 in the third lens group G3. The image surface of the negative meniscus lens L8 and the object side surface of the positive meniscus lens L9 in the fourth lens group G4 are provided on eight surfaces.

  Next, numerical data of optical members constituting the zoom lens of each of the above embodiments will be listed. In the numerical data of each embodiment, r1, r2,... Are the curvature radii of the lens surfaces, d1, d2,... Are the thickness or air spacing of each lens, and nd1, nd2,. Are the Abbe number of each lens, Fno. Is the F number, f is the focal length of the entire system, and D0 is the distance from the object to the first surface. * Indicates an aspherical surface.

The aspherical shape is expressed by the following equation when the optical axis direction is z, the direction orthogonal to the optical axis is y, the conical coefficient is K, and the aspherical coefficients are A4, A6, A8, and A10. .
z = (y ² / r) / [1+ {1− (1 + K) (y / r) ² } ^1/2 ]
+ A4y ⁴ + A6y ⁶ + A8y ⁸ + A10y ¹⁰
E represents a power of 10. The symbols of these specification values are common to the numerical data of the examples described later.

Numerical example 1
Unit mm

Surface data

Surface number rd nd νd ER
Object ∞ ∞
1 15.0983 0.8000 1.92286 18.90 8.226
2 10.8694 0.5500 1.63387 23.38 7.312
3 * 12.1434 3.3297 1.69350 53.21 7.214
4 * 3434.1874 Variable 6.500
5 294.9005 0.7500 1.88300 40.76 5.287
6 4.2780 2.3932 3.500
7 * -40.8657 0.6000 1.74320 49.34 3.589
8 * 11.3290 0.1000 3.568
9 8.1057 1.2896 1.94595 17.98 3.643
10 23.2715 Variable 3.550
11 (Aperture) ∞ -0.3000 2.073
12 * 3.8131 1.8486 1.45650 90.27 2.175
13 * -9.5580 0.1000 2.160
14 4.9226 1.1000 2.10225 16.80 2.091
15 * 3.2167 Variable 1.763
16 * 11.0842 1.5702 1.45650 90.27 4.282
17 1189.9791 Variable 4.267
18 ∞ 0.3000 1.51633 64.14 4.110
19 ∞ 0.5000 4.110
20 ∞ 0.5000 1.51633 64.14 4.088
21 ∞ 0.565 4.088
Image plane ∞

Aspheric data 3rd surface
K = 0.000, A4 = 1.17931e-05

4th page
K = 0.000, A4 = 1.69041e-05, A6 = 7.41794e-09, A8 = -1.12289e-09, A10 = 8.14927e-12

7th page
K = -210.654, A4 = -1.06726e-04, A6 = 3.07542e-06, A8 = 1.51089e-06, A10 = -7.45716e-08

8th page
K = -0.679, A4 = 1.09834e-06, A6 = 3.75292e-06, A8 = 9.07784e-08, A10 = -6.63271e-08

12th page
K = -0.206, A4 = -1.09869e-03, A6 = -3.35370e-05, A8 = -5.61745e-06, A10 = 2.26288e-06

13th page
K = -9.497, A4 = 3.72223e-04, A6 = -2.84469e-05, A8 = 1.40847e-06, A10 = 3.19085e-06

15th page
K = 0.081, A4 = -6.87102e-05, A6 = 8.18436e-05, A8 = 1.61531e-05, A10 = -3.60629e-06

16th page
K = 0.000, A4 = 6.82641e-05, A6 = 2.68204e-06, A8 = 4.24074e-08

Various data

Zoom ratio 9.919

Wide angle Medium telephoto

Focal length 4.830 14.650 47.910
FNO. 3.230 4.843 5.298
Angle of view 2ω 81.504 29.768 9.055
Image height 3.830 3.830 3.830
BF 4.392 8.027 4.866
Total lens length 34.253 41.031 46.727
Object distance ∞ ∞ ∞
d4 0.248 5.406 13.277
d10 10.022 3.888 0.500
d15 5.459 9.580 13.952
d17 2.800 6.343 3.500
Diaphragm diameter 2.073 2.073 2.073
Entrance pupil position 9.775 21.574 74.245
Exit pupil position -10.210 -20.298 -40.720
Front principal point position 13.007 28.647 71.802
Rear principal point position -4.266 -13.994 -47.572

Lens Start surface Focal length
L1 1 -46.249
L2 2 139.999
L3 3 17.565
L4 5 -4.922
L5 7 -11.877
L6 9 12.627
L7 12 6.241
L8 14 -12.722
L9 16 24.499
L10 18 ∞
L11 20 ∞


Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 25.150 4.680 -0.199 -2.913
G2 5 -4.646 5.133 0.541 -3.227
G3 11 8.094 2.749 -2.040 -2.827
G4 16 24.499 1.570 -0.010 -1.088

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.277 -0.399 -1.231
G3 -0.895 -2.325 -2.044
G4 0.776 0.628 0.757

Numerical example 2
Unit mm

Surface data

Surface number rd nd νd ER
Object ∞ ∞
1 16.0826 0.8000 1.92286 18.90 8.274
2 11.7359 0.4500 1.63387 23.38 7.420
3 * 12.5279 3.4125 1.69350 53.21 7.294
4 * 1275.3837 Variable 6.500
5 170.0064 0.7500 1.88300 40.76 5.344
6 4.4474 2.3602 3.600
7 * -39.8327 0.6000 1.74320 49.34 3.680
8 * 13.2170 0.1000 3.618
9 7.9913 1.2896 1.94595 17.98 3.679
10 19.5384 Variable 3.550
11 (Aperture) ∞ -0.3000 2.099
12 * 3.8738 1.8486 1.45650 90.27 2.191
13 * -12.4941 0.1000 2.165
14 4.7299 1.1000 2.10225 16.80 2.100
15 * 3.2121 Variable 1.763
16 * 11.0451 1.5702 1.45650 90.27 4.181
17 496.0788 Variable 4.400
18 ∞ 0.3000 1.51633 64.14 4.063
19 ∞ 0.5000 4.057
20 ∞ 0.5000 1.51633 64.14 4.043
21 ∞ 0.500 4.051
Image plane ∞

Aspheric data

Third side
K = 0.000, A4 = 7.94216e-06

4th page
K = 0.000, A4 = 1.44661e-05, A6 = 4.44758e-09, A8 = -8.01168e-10, A10 = 6.71467e-12

7th page
K = -210.654, A4 = 1.73814e-04, A6 = 3.07542e-06, A8 = 1.51089e-06, A10 = -7.45716e-08

8th page
K = -0.679, A4 = 3.64745e-04, A6 = 3.75292e-06, A8 = 9.07784e-08, A10 = -6.63271e-08

12th page
K = -0.206, A4 = -7.53379e-04, A6 = -3.35370e-05, A8 = -5.61745e-06, A10 = 2.26288e-06

13th page
K = -9.497, A4 = 3.72223e-04, A6 = -2.84469e-05, A8 = 1.40847e-06, A10 = 3.19085e-06

15th page
K = 0.081, A4 = 6.00090e-04, A6 = 8.18436e-05, A8 = 1.61531e-05, A10 = -3.60629e-06

16th page
K = 0.000, A4 = 6.59060e-05, A6 = 2.68204e-06, A8 = 4.24074e-08

Various data

Zoom ratio 9.908

Wide angle Medium telephoto

Focal length 4.836 14.651 47.915
FNO. 3.230 4.718 4.967
Angle of view 2ω 80.779 29.701 9.048
Image height 3.830 3.830 3.830
BF 4.333 8.686 4.993
Total lens length 35.395 41.202 46.730
Object distance ∞ ∞ ∞
d4 0.248 5.780 14.479
d10 11.068 4.119 0.500
d15 5.665 8.535 12.677
d17 2.800 7.159 3.500
Diaphragm diameter 2.099 2.099 2.099
Entrance pupil position 10.015 22.259 80.511
Exit pupil position -10.553 -17.087 -32.593
Front principal point position 13.280 28.581 67.343
Rear principal point position -4.330 -14.151 -47.450

Lens Start surface Focal length
L1 1 -51.611
L2 2 239.973
L3 3 18.224
L4 5 -5.183
L5 7 -13.289
L6 9 13.558
L7 12 6.715
L8 14 -14.646
L9 16 24.721
L10 18 ∞
L11 20 ∞


Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 26.692 4.662 -0.225 -2.923
G2 5 -4.980 5.100 0.539 -3.187
G3 11 8.431 2.749 -2.138 -2.903
G4 16 24.721 1.570 -0.025 -1.101

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.277 -0.399 -1.320
G3 -0.840 -2.276 -1.804
G4 0.780 0.604 0.753

Numerical Example 3
Unit mm

Surface data

Surface number rd nd νd ER
Object ∞ ∞
1 14.6386 0.8000 1.94595 17.98 8.126
2 10.6769 0.6000 1.63387 23.38 7.227
3 * 11.6730 3.1477 1.69350 53.21 7.152
4 * 1335.0365 Variable 6.500
5 748.5511 0.7500 1.88300 40.76 5.189
6 4.1942 2.3409 3.369
7 * -52.5094 0.6000 1.74320 49.34 3.535
8 * 11.3904 0.1000 3.536
9 8.7252 1.2896 1.94595 17.98 3.600
10 28.0148 Variable 3.550
11 (Aperture) ∞ -0.3000 2.086
12 * 3.7868 1.8486 1.45650 90.27 2.198
13 * -11.0791 0.1000 2.178
14 4.6374 1.1000 2.10225 16.80 2.109
15 * 3.1111 Variable 1.763
16 * 11.2112 1.5702 1.45650 90.27 4.397
17 1446.9138 Variable 4.400
18 ∞ 0.3000 1.51633 64.14 4.132
19 ∞ 0.5000 4.119
20 ∞ 0.5000 1.51633 64.14 4.085
21 ∞ 0.485 4.070
Image plane ∞

Aspheric data

Third side
K = 0.000, A4 = -4.93361e-05,

4th page
K = 0.000, A4 = 1.07866e-05, A6 = 8.96694e-08, A8 = -2.44681e-09, A10 = 2.50980e-11

7th page
K = -210.654, A4 = -1.12025e-04, A6 = 3.07542e-06, A8 = 1.51089e-06, A10 = -7.45716e-08

8th page
K = -0.679, A4 = -3.24954e-04, A6 = 3.75292e-06, A8 = 9.07784e-08, A10 = -6.63271e-08

12th page
K = -0.206, A4 = -8.95478e-04, A6 = -3.81951e-05, A8 = -5.61745e-06, A10 = 2.26288e-06

13th page
K = -9.497, A4 = 3.72223e-04, A6 = -2.84469e-05, A8 = 1.40847e-06, A10 = 3.19085e-06

15th page
K = 0.081, A4 = 4.33982e-04, A6 = 1.05672e-04, A8 = 1.75021e-05, A10 = -3.60629e-06

16th page
K = 0.000, A4 = 1.52982e-04, A6 = 2.68204e-06, A8 =, A10 = 4.24074e-08

Various data

Zoom ratio 9.908

Wide angle Medium telephoto

Focal length 4.836 14.650 47.910
FNO. 3.230 4.614 5.454
Angle of view 2ω 81.748 29.770 9.195
Image height 3.830 3.830 3.830
BF 4.313 7.294 4.977
Total lens length 34.049 40.652 46.767
Object distance ∞ ∞ ∞
d4 0.248 6.175 12.809
d10 10.016 4.197 0.500
d15 5.525 9.039 14.535
d17 2.800 5.741 3.500
Diaphragm diameter 2.086 2.086 2.086
Entrance pupil position 9.592 24.650 70.006
Exit pupil position -10.283 -18.495 -44.152
Front principal point position 12.826 30.978 71.194
Rear principal point position -4.350 -14.124 -47.461

Lens Start surface Focal length
L1 1 -46.246
L2 2 160.011
L3 3 16.964
L4 5 -4.779
L5 7 -12.544
L6 9 12.974
L7 12 6.433
L8 14 -13.785
L9 16 24.742
L10 18 ∞
L12 20 ∞


Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 24.623 4.548 -0.231 -2.861
G2 5 -4.616 5.080 0.488 -3.265
G3 11 8.068 2.749 -2.094 -2.850
G4 16 24.742 1.570 -0.008 -1.086

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.281 -0.440 -1.199
G3 -0.893 -2.043 -2.149
G4 0.782 0.661 0.755

Numerical Example 4
Unit mm

Surface data

Surface number rd nd νd ER
Object ∞ ∞
1 14.6144 0.8000 1.94595 17.98 8.026
2 10.8345 0.6000 1.63387 23.38 7.169
3 * 11.8699 2.9617 1.69350 53.21 7.036
4 * 1550.2690 Variable 6.500
5 407.1135 0.7500 1.88300 40.76 5.289
6 4.3022 2.3288 3.458
7 * -39.9420 0.6000 1.74320 49.34 3.601
8 * 11.8340 0.1000 3.591
9 8.7555 1.2896 1.94595 17.98 3.652
10 28.8153 Variable 3.550
11 (Aperture) ∞ -0.3000 2.096
12 * 3.8419 1.8486 1.45650 90.27 2.198
13 * -10.5663 0.1000 2.176
14 4.7517 1.1000 2.10225 16.80 2.102
15 * 3.1540 Variable 1.763
16 * 11.2385 1.5702 1.45650 90.27 4.387
17 1445.1029 Variable 4.400
18 ∞ 0.3000 1.51633 64.14 4.129
19 ∞ 0.5000 4.116
20 ∞ 0.5000 1.51633 64.14 4.083
21 ∞ 0.487 4.073
Image plane ∞

Aspheric data 3rd surface
K = 0.000, A4 = 1.79282e-04, A6 = -3.79928e-06

4th page
K = 0.000, A4 = 4.08669e-05, A6 = -8.29226e-07, A8 = 8.03112e-09, A10 = -3.08535e-11

7th page
K = -210.654, A4 = -2.25142e-04, A6 = 3.07542e-06, A8 = 1.51089e-06, A10 = -7.45716e-08

8th page
K = -0.679, A4 = -2.12917e-04, A6 = 3.75292e-06, A8 = 9.07784e-08, A10 = -6.63271e-08

12th page
K = -0.206, A4 = -1.16036e-03, A6 = -1.21065e-05, A8 = -5.61745e-06, A10 = 2.26288e-06

13th page
K = -9.497, A4 = 3.72223e-04, A6 = -2.84469e-05, A8 = 1.40847e-06, A10 = 3.19085e-06

15th page
K = 0.081, A4 = -3.51617e-05, A6 = 1.10331e-04, A8 = 1.07663e-05, A10 = -3.60629e-06

16th page
K = 0.000, A4 = 1.16671e-04, A6 = 2.68204e-06, A8 = 4.24074e-08

Various data

Zoom ratio 9.908

Wide angle Medium telephoto

Focal length 4.836 14.650 47.911
FNO. 3.230 4.540 5.519
Angle of view 2ω 81.822 29.697 9.168
Image height 3.830 3.830 3.830
BF 4.315 7.291 4.998
Total lens length 34.441 40.516 46.740
Object distance ∞ ∞ ∞
d4 0.248 6.218 12.481
d10 10.506 4.415 0.500
d15 5.624 8.843 15.012
d17 2.800 5.730 3.500
Diaphragm diameter 2.096 2.096 2.096
Entrance pupil position 9.611 24.985 66.290
Exit pupil position -10.468 -17.915 -47.752
Front principal point position 12.864 31.120 70.685
Rear principal point position -4.348 -14.116 -47.441

Lens Start surface Focal length
L1 1 -49.363
L2 2 159.990
L3 3 17.234
L4 5 -4.929
L5 7 -12.223
L6 9 12.893
L7 12 6.430
L8 14 -13.319
L9 16 24.803
L10 18 ∞
L11 20 ∞


Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 24.322 4.362 -0.220 -2.741
G2 5 -4.718 5.068 0.500 -3.243
G3 11 8.240 2.749 -2.116 -2.875
G4 16 24.803 1.570 -0.008 -1.086

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.293 -0.465 -1.215
G3 -0.868 -1.956 -2.148
G4 0.782 0.662 0.755

Numerical Example 5
Unit mm

Surface data

Surface number rd nd νd ER
Object ∞ ∞
1 14.5197 0.8000 1.94595 17.98 8.129
2 * 10.7359 0.6000 1.63387 23.38 7.236
3 * 11.7470 3.1914 1.69350 53.21 7.148
4 * 1829.6540 Variable 6.500
5 199.2213 0.7500 1.88300 40.76 4.966
6 3.8397 2.1487 3.093
7 * -45.5839 0.6000 1.74320 49.34 3.000
8 * 12.7740 0.1000 3.381
9 10.2362 1.2896 1.94595 17.98 3.437
10 58.3743 Variable 3.550
11 (Aperture) ∞ -0.3000 2.096
12 * 3.9456 1.8486 1.45650 90.27 2.185
13 * -9.6152 0.1000 2.159
14 5.1988 1.1000 2.10225 16.80 2.080
15 * 3.4694 Variable 1.763
16 * 11.0945 1.5702 1.45650 90.27 4.425
17 3386.5614 Variable 4.400
18 ∞ 0.3000 1.51633 64.14 4.159
19 ∞ 0.5000 4.159
20 ∞ 0.5000 1.51633 64.14 4.115
21 ∞ 0.406 4.115
Image plane ∞

Aspheric data

Second side
K = 0.000, A4 = 1.55845e-05, A6 = -5.66319e-08

Third side
K = 0.000, A4 = -2.59071e-05

4th page
K = 0.000, A4 = 5.54785e-06, A6 = 2.02921e-07, A8 = -2.00915e-09, A10 = 4.78740e-12

7th page
K = -210.654, A4 = -1.21601e-03, A6 = 3.07542e-06, A8 = 1.51089e-06, A10 = -7.45716e-08

8th page
K = -0.679, A4 = -1.54035e-03, A6 = 3.75292e-06, A8 = 9.07784e-08, A10 = -6.63271e-08

12th page
K = -0.206, A4 = -6.57693e-04, A6 = -2.03892e-05, A8 = -5.61745e-06, A10 = 2.26288e-06

13th page
K = -9.497, A4 = 3.72223e-04, A6 = -2.84469e-05, A8 = 1.40847e-06, A10 = 3.19085e-06

15th page
K = 0.081, A4 = 3.50082e-04, A6 = 1.15620e-04, A8 = 2.18755e-05, A10 = -3.60629e-06

16th page
K = 0.000, A4 = 8.89856e-05, A6 = 2.68204e-06, A8 = 4.24074e-08

Various data

Zoom ratio 9.907

Wide angle Medium telephoto

Focal length 4.836 14.652 47.915
FNO. 3.230 4.502 5.470
Angle of view 2ω 81.359 29.580 9.101
Image height 3.830 3.830 3.830
BF 4.233 7.478 4.306
Total lens length 34.036 40.617 46.750
Object distance ∞ ∞ ∞
d4 0.248 6.351 12.645
d10 9.773 4.011 0.500
d15 5.983 8.978 15.501
d17 2.800 5.824 2.885
Diaphragm diameter 2.096 2.096 2.096
Entrance pupil position 9.354 25.223 69.717
Exit pupil position -11.307 -18.615 -54.319
Front principal point position 12.685 31.648 78.470
Rear principal point position -4.431 -14.025 -47.522

Lens Start surface Focal length
L1 1 -48.540
L2 2 159.956
L3 3 17.036
L4 5 -4.442
L5 7 -13.367
L6 9 12.953
L7 12 6.402
L8 14 -14.196
L9 16 24.380
L10 18 ∞
L11 20 ∞


Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 24.157 4.591 -0.217 -2.874
G2 5 -4.535 4.888 0.366 -3.308
G3 11 8.119 2.749 -1.859 -2.737
G4 16 24.380 1.570 -0.004 -1.081

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.281 -0.452 -1.214
G3 -0.911 -2.067 -2.098
G4 0.782 0.649 0.779

Numerical Example 6
Unit mm

Surface data

Surface number rd nd νd ER
Object ∞ ∞
1 14.7078 0.8000 1.94595 17.98 8.085
2 10.6580 0.6000 1.63387 23.38 7.186
3 * 11.6497 3.0722 1.69350 53.21 7.120
4 * 1422.6400 Variable 6.500
5 297.4089 0.7500 1.88300 40.76 5.238
6 4.2117 2.4218 3.376
7 * -39.7619 0.6000 1.74320 49.34 3.547
8 * 11.6213 0.1000 3.548
9 8.7480 1.2896 1.94595 17.98 3.615
10 30.2959 Variable 3.550
11 (Aperture) ∞ -0.3000 2.080
12 * 3.8155 1.8486 1.45650 90.27 2.186
13 * -10.1210 0.1000 2.168
14 4.8004 1.1000 2.10225 16.80 2.099
15 * 3.1672 Variable 1.763
16 * 11.1381 1.5702 1.45650 90.27 4.397
17 3330.5764 Variable 4.400
18 ∞ 0.3000 1.51633 64.14 4.135
19 ∞ 0.5000 4.135
20 ∞ 0.5000 1.51633 64.14 4.102
21 ∞ 0.484 4.102
Image plane ∞

Aspheric data

Third side
K = 0.000, A4 = -5.99764e-05

4th page
K = 0.000, A4 = 8.84943e-06, A6 = 8.77088e-08, A8 = -1.97842e-09, A10 = 1.85258e-11

7th page
K = -210.654, A4 = -2.62609e-04, A6 = 3.07542e-06, A8 = 1.51089e-06, A10 = -7.45716e-08

8th page
K = -0.679, A4 = -2.42403e-04, A6 = 3.75292e-06, A8 = 9.07784e-08, A10 = -6.63271e-08

12th page
K = -0.206, A4 = -1.09091e-03, A6 = -1.87003e-05, A8 = -5.61745e-06, A10 = 2.26288e-06

13th page
K = -9.497, A4 = 3.72223e-04, A6 = -2.84469e-05, A8 = 1.40847e-06, A10 = 3.19085e-06

15th page
K = 0.081, A4 = 1.82908e-04, A6 = 2.30143e-05, A8 = 3.11600e-05, A10 = -3.60629e-06

16th page
K = 0.000, A4 = 1.28607e-04, A6 = 2.68204e-06, A8 = 4.24074e-08

Various data

Zoom ratio 9.901

Wide angle Medium telephoto

Focal length 4.839 14.650 47.910
FNO. 3.230 4.581 5.444
Angle of view 2ω 81.614 29.651 9.121
Image height 3.830 3.830 3.830
BF 4.545 7.361 4.490
Total lens length 33.991 40.734 46.731
Object distance ∞ ∞ ∞
d4 0.248 6.393 13.035
d10 9.916 4.155 0.500
d15 5.331 8.872 14.754
d17 3.084 5.776 2.978
Diaphragm diameter 2.080 2.080 2.080
Entrance pupil position 9.523 25.256 71.680
Exit pupil position -9.969 -18.166 -46.810
Front principal point position 12.749 31.498 74.845
Rear principal point position -4.406 -14.092 -47.426

Lens Start surface Focal length
L1 1 -45.266
L2 2 159.977
L3 3 16.922
L4 5 -4.844
L5 7 -12.040
L6 9 12.635
L7 12 6.333
L8 14 -13.057
L9 16 24.477
L10 18 ∞
L11 20 ∞


Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 24.818 4.472 -0.231 -2.816
G2 5 -4.657 5.161 0.491 -3.352
G3 11 8.137 2.749 -2.081 -2.850
G4 16 24.477 1.570 -0.004 -1.082

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.280 -0.445 -1.219
G3 -0.903 -2.024 -2.050
G4 0.770 0.655 0.772

Numerical Example 7
Unit mm

Surface data

Surface number rd nd νd ER
Object ∞ ∞
1 14.6642 0.8000 1.94595 17.98 8.137
2 10.6800 0.6000 1.63387 23.38 7.237
3 * 11.6770 3.1686 1.69350 53.21 7.143
4 * 1347.7185 Variable 6.500
5 362.1185 0.7500 1.88300 40.76 5.260
6 4.2272 2.4018 3.402
7 * -46.8839 0.6000 1.74320 49.34 3.571
8 * 11.4555 0.1000 3.571
9 8.7456 1.2896 1.94595 17.98 3.637
10 27.9802 Variable 3.550
11 (Aperture) ∞ -0.3000 2.094
12 * 3.7982 1.8486 1.45650 90.27 2.201
13 * -10.9452 0.1000 2.178
14 4.6824 1.1000 2.10225 16.80 2.108
15 * 3.1299 Variable 1.763
16 * 11.1339 1.5702 1.45650 90.27 4.376
17 1805.4685 Variable 4.400
18 ∞ 0.3000 1.51633 64.14 4.127
19 ∞ 0.5000 4.114
20 ∞ 0.5000 1.51633 64.14 4.082
21 ∞ 0.443 4.063
Image plane ∞

Aspheric data

Third side
K = 0.000, A4 = -3.45595e-05

4th page
K = 0.000, A4 = 1.25106e-05, A6 = 6.58008e-08, A8 = -2.08900e-09, A10 = 2.11407e-11

7th page
K = -210.654, A4 = -1.68311e-04, A6 = 3.07542e-06, A8 = 1.51089e-06, A10 = -7.45716e-08

8th page
K = -0.679, A4 = -2.88240e-04, A6 = 3.75292e-06, A8 = 9.07784e-08, A10 = -6.63271e-08

12th page
K = -0.206, A4 = -9.55038e-04, A6 = -3.13344e-05, A8 = -5.61745e-06, A10 = 2.26288e-06

13th page
K = -9.497, A4 = 3.72223e-04, A6 = -2.84469e-05, A8 = 1.40847e-06, A10 = 3.19085e-06

15th page
K = 0.081, A4 = 3.45391e-04, A6 = 9.75897e-05, A8 = 1.79381e-05, A10 = -3.60629e-06

16th page
K = 0.000, A4 = 1.29613e-04, A6 = 2.68204e-06, A8 = 4.24074e-08

Various data

Zoom ratio 9.910

Wide angle Medium telephoto

Focal length 4.834 14.650 47.910
FNO. 3.230 4.562 5.384
Angle of view 2ω 81.425 29.686 9.161
Image height 3.830 3.830 3.830
BF 4.270 7.392 4.965
Total lens length 34.315 40.778 46.760
Object distance ∞ ∞ ∞
d4 0.248 6.293 12.880
d10 10.128 4.229 0.500
d15 5.640 8.835 14.386
d17 2.800 5.791 3.500
Diaphragm diameter 2.094 2.094 2.094
Entrance pupil position 9.682 25.264 71.253
Exit pupil position -10.536 -18.016 -43.687
Front principal point position 12.938 31.466 71.984
Rear principal point position -4.392 -14.076 -47.472

Lens Start surface Focal length
L1 1 -46.050
L2 2 159.981
L3 3 16.969
L4 5 -4.849
L5 7 -12.333
L6 9 13.024
L7 12 6.430
L8 14 -13.627
L9 16 24.534
L10 18 ∞
L11 20 ∞


Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 24.685 4.569 -0.232 -2.874
G2 5 -4.628 5.141 0.510 -3.293
G3 11 8.120 2.749 -2.100 -2.858
G4 16 24.534 1.570 -0.007 -1.084

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.282 -0.446 -1.220
G3 -0.889 -2.034 -2.111
G4 0.782 0.654 0.753

Numerical Example 8
Unit mm

Surface data

Surface number rd nd νd ER
Object ∞ ∞
1 14.8030 0.8000 1.94595 17.98 8.144
2 * 10.8313 0.6000 1.63387 23.38 7.242
3 * 11.8660 3.1875 1.69350 53.21 7.162
4 * 1239.2277 Variable 6.500
5 301.4761 0.7500 1.88300 40.76 5.292
6 4.2629 2.4056 3.431
7 * -43.1844 0.6000 1.74320 49.34 3.587
8 * 11.7576 0.1000 3.572
9 8.7365 1.2896 1.94595 17.98 3.632
10 27.9064 Variable 3.550
11 (Aperture) ∞ -0.3000 2.077
12 * 3.7847 1.8486 1.45650 90.27 2.187
13 * -11.0006 0.1000 2.169
14 4.7151 1.1000 2.10225 16.80 2.103
15 * 3.1461 Variable 1.763
16 * 11.0533 1.5702 1.45650 90.27 4.363
17 1546.1884 Variable 4.400
18 ∞ 0.3000 1.51633 64.14 4.136
19 ∞ 0.5000 4.123
20 ∞ 0.5000 1.51633 64.14 4.089
21 ∞ 0.482 4.073
Image plane ∞

Aspheric data

Second side
K = 0.000, A4 = 9.85840e-06, A6 = 7.62206e-08, A8 = -5.17542e-11

Third side
K = 0.000, A4 = -3.06277e-05

4th page
K = 0.000, A4 = 5.57710e-06, A6 = 6.98142e-08, A8 = -1.39376e-09, A10 = 1.70036e-11

7th page
K = -210.654, A4 = -1.42552e-04, A6 = 3.07542e-06, A8 = 1.51089e-06, A10 = -7.45716e-08

8th page
K = -0.679, A4 = -1.86046e-04, A6 = 3.75292e-06, A8 = 9.07784e-08, A10 = -6.63271e-08

12th page
K = -0.206, A4 = -9.92630e-04, A6 = -2.90833e-05, A8 = -5.61745e-06, A10 = 2.26288e-06

13th page
K = -9.497, A4 = 3.72223e-04, A6 = -2.84469e-05, A8 = 1.40847e-06, A10 = 3.19085e-06

15th page
K = 0.081, A4 = 3.92713e-04, A6 = 8.37259e-05, A8 = 2.17878e-05, A10 = -3.60629e-06

16th page
K = 0.000, A4 = 1.23393e-04, A6 = 2.68204e-06, A8 = 4.24074e-08

Various data

Zoom ratio 9.911

Wide angle Medium telephoto

Focal length 4.834 14.650 47.910
FNO. 3.230 4.605 5.451
Angle of view 2ω 81.134 29.679 9.113
Image height 3.830 3.830 3.830
BF 4.277 7.315 4.438
Total lens length 34.275 40.691 46.715
Object distance ∞ ∞ ∞
d4 0.248 6.184 12.942
d10 10.155 4.159 0.500
d15 5.544 8.981 14.783
d17 2.800 5.734 2.928
Diaphragm diameter 2.077 2.077 2.077
Entrance pupil position 9.740 24.712 70.884
Exit pupil position -10.375 -18.515 -47.351
Front principal point position 12.979 31.053 74.472
Rear principal point position -4.385 -14.097 -47.428

Lens Start surface Focal length
L1 1 -47.308
L2 2 159.972
L3 3 17.257
L4 5 -4.903
L5 7 -12.377
L6 9 13.019
L7 12 6.420
L8 14 -13.563
L9 16 24.380
L10 18 ∞
L11 20 ∞


Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 24.888 4.587 -0.234 -2.887
G2 5 -4.692 5.145 0.507 -3.305
G3 11 8.129 2.749 -2.101 -2.860
G4 16 24.380 1.570 -0.008 -1.085

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.283 -0.442 -1.215
G3 -0.879 -2.033 -2.048
G4 0.780 0.655 0.773

Numerical Example 9
Unit mm

Surface data

Surface number rd nd νd ER
Object ∞ ∞
1 12.8240 0.8000 1.94595 17.98 8.066
2 10.6537 0.6000 1.63387 23.38 7.320
3 * 11.6481 3.2092 1.49700 81.54 7.177
4 * 53673.2484 Variable 6.500
5 50.4110 0.7500 1.88300 40.76 5.328
6 4.1301 2.7243 3.487
7 * -46.1397 0.6000 1.74320 49.34 3.407
8 * 17.6596 0.1000 3.628
9 10.9976 1.2896 1.94595 17.98 3.664
10 33.7377 Variable 3.550
11 (Aperture) ∞ -0.3000 2.133
12 * 3.8227 1.8486 1.45650 90.27 2.244
13 * -12.5034 0.1000 2.203
14 4.6982 1.1000 2.10225 16.80 2.117
15 * 3.2163 Variable 1.763
16 * 18.8194 1.5702 1.45650 90.27 4.059
17 48945.0859 Variable 4.400
18 ∞ 0.3000 1.51633 64.14 4.052
19 ∞ 0.5000 4.052
20 ∞ 0.5000 1.51633 64.14 4.050
21 ∞ 0.522 4.050
Image plane ∞

Aspheric data

Third side
K = 0.000, A4 = 2.85162e-06

4th page
K = 0.000, A4 = 3.28559e-05, A6 = 1.55273e-08, A8 = -9.84943e-10, A10 = 9.63167e-12

7th page
K = -210.654, A4 = -7.25729e-04, A6 = 3.07542e-06, A8 = 1.51089e-06, A10 = -7.45716e-08

8th page
K = -0.679, A4 = -8.43466e-04, A6 = 3.75292e-06, A8 = 9.07784e-08, A10 = -6.63271e-08

12th page
K = -0.206, A4 = -4.18286e-04, A6 = -4.22134e-05, A8 = -5.61745e-06, A10 = 2.26288e-06

13th page
K = -9.497, A4 = 3.72223e-04, A6 = -2.84469e-05, A8 = 1.40847e-06, A10 = 3.19085e-06

15th page
K = 0.081, A4 = 1.11391e-03, A6 = 1.24502e-04, A8 = 3.59501e-05, A10 = -3.60629e-06

16th page
K = 0.000, A4 = 3.97958e-04, A6 = 2.68204e-06, A8 = 4.24074e-08

Various data

Zoom ratio 9.896

Wide angle Medium telephoto

Focal length 4.841 14.647 47.906
FNO. 3.230 4.851 5.645
Angle of view 2ω 82.117 30.384 9.500
Image height 3.830 3.830 3.830
BF 4.198 7.271 5.169
Total lens length 35.302 40.979 48.915
Object distance ∞ ∞ ∞
d4 0.248 6.211 15.002
d10 11.162 4.287 0.500
d15 5.303 8.819 13.851
d17 2.800 5.721 3.500
Diaphragm diameter 2.133 2.133 2.133
Entrance pupil position 10.467 23.808 77.511
Exit pupil position -8.796 -14.310 -24.775
Front principal point position 13.505 28.514 48.775
Rear principal point position -4.471 -14.125 -47.264

Lens Start surface Focal length
L1 1 -81.076
L2 2 159.536
L3 3 23.441
L4 5 -5.134
L5 7 -17.116
L6 9 16.786
L7 12 6.649
L8 14 -15.145
L9 16 41.241
L10 18 ∞
L11 20 ∞


Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 29.280 4.609 -0.623 -3.520
G2 5 -5.129 5.464 0.462 -3.718
G3 11 8.174 2.749 -2.056 -2.841
G4 16 41.241 1.570 -0.000 -1.078

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.257 -0.367 -0.992
G3 -0.736 -1.707 -1.943
G4 0.872 0.798 0.849

Next, the values of the conditional expressions in each example are listed.

(1) ΔD12 / ((ΣD1 + ΣD2) × γ × tanω)
(2) ΔV2 / ΔV1
(3) ΔVL / fw
(4) | (P0−Ph) / P0 |
(5) SF3
(6) SFL
(7) f1T1 / f1
(8) θgFT1

Example Conditional expression
(1) (2) (3) (4) (5) (6) (7) (8)
1 0.155 -0.026 0.145 0.0153 4.771 -1.019 5.567 0.668
2 0.173 -0.251 0.145 0.0113 5.232 -1.046 8.990 0.668
3 0.152 0.015 0.145 0.0613 5.077 -1.016 6.499 0.668
4 0.151 0.007 0.145 0.1398 4.948 -1.016 6.578 0.668
5 0.154 0.026 0.018 0.0319 5.012 -1.007 6.622 0.668
6 0.155 -0.008 -0.022 0.0748 4.879 -1.007 6.446 0.668
7 0.153 -0.015 0.145 0.0423 5.032 -1.012 6.481 0.695
8 0.154 -0.023 0.027 0.0390 5.010 -1.014 6.428 0.722
9 0.170 -0.106 0.145 0.0033 5.341 -1.001 6.428 0.668

  The imaging optical system of the present invention as described above is a photographing apparatus for photographing an image of an object with an electronic image sensor such as a CCD or a CMOS, especially a digital camera, a video camera, a personal computer or an example of an information processing apparatus, a telephone. It can be used for portable terminals, especially mobile phones that are convenient to carry. The embodiment is illustrated below.

  FIGS. 19 to 21 are conceptual diagrams of structures in which the imaging optical system according to the present invention is incorporated in the photographing optical system 41 of a digital camera. 19 is a front perspective view showing the appearance of the digital camera 40, FIG. 20 is a rear perspective view thereof, and FIG. 21 is a cross-sectional view showing an optical configuration of the digital camera 40.

  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 45, a flash 46, a liquid crystal display monitor 47, and the like. Then, when the photographer presses the shutter 45 disposed on the upper part of the camera 40, photographing is performed through the photographing optical system 41, for example, the zoom lens 48 of the first embodiment in conjunction therewith.

  The object image formed by the photographing optical system 41 is formed on the image pickup surface of the CCD 49. 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 image processing means 51. Further, the image processing means 51 is provided with a memory or the like, and can record a captured electronic image. This memory may be provided separately from the image processing means 51, or may be configured to perform recording and writing electronically using a flexible disk, memory card, MO, or the like.

  Further, a finder objective optical system 53 is disposed on the finder optical path 44. The finder objective optical system 53 includes a cover lens 54, a first prism 10, an aperture stop 2, a second prism 20, and a focusing lens 66. An object image is formed on the imaging surface 67 by the finder objective optical system 53. This object image is formed on the field frame 57 of the Porro prism 55 which is an image erecting member. Behind the Porro prism 55, an eyepiece optical system 59 for guiding an erect image to the observer eyeball E is disposed.

  According to the digital camera 40 configured as described above, an electronic imaging device having a compact and thin zoom lens in which the number of components of the photographing optical system 41 is reduced can be realized. The present invention is not limited to the above-described retractable digital camera, but can also be applied to a folding digital camera that employs a bending optical system.

  Next, a personal computer which is an example of an information processing apparatus in which the imaging optical system of the present invention is incorporated as an objective optical system is shown in FIGS. 22 is a front perspective view of the personal computer 300 with the cover open, FIG. 23 is a sectional view of the photographing optical system 303 of the personal computer 300, and FIG. 24 is a side view of FIG. As shown in FIGS. 22 to 24, the personal computer 300 includes a keyboard 301, information processing means and recording means, a monitor 302, and a photographing optical system 303.

  Here, the keyboard 301 is for an operator to input information from the outside. The information processing means and recording means are not shown. The monitor 302 is for displaying information to the operator. The photographing optical system 303 is for photographing an image of the operator himself or a surrounding area. The monitor 302 may be a liquid crystal display element, a CRT display, or the like. Examples of the liquid crystal display element include a transmissive liquid crystal display element that illuminates from the back with a backlight (not shown), and a reflective liquid crystal display element that reflects and displays light from the front. Further, in the drawing, the photographing optical system 303 is built in the upper right of the monitor 302. However, the imaging optical system 303 is not limited to the place, and may be anywhere around the monitor 302 or the keyboard 301.

  The photographing optical system 303 includes, on the photographing optical path 304, the objective optical system 100 including, for example, the zoom lens according to the first embodiment, and the electronic imaging element chip 162 that receives an image. These are built in the personal computer 300.

A cover glass 102 for protecting the objective optical system 100 is disposed at the tip of the mirror frame.
The object image received by the electronic image sensor chip 162 is input to the processing means of the personal computer 300 via the terminal 166. Finally, the object image is displayed on the monitor 302 as an electronic image. FIG. 22 shows an image 305 taken by the operator as an example. The image 305 can also be displayed on a communication partner's personal computer from a remote location via the processing means. The Internet and telephone are used for image transmission to remote places.

  Next, FIG. 25 shows a telephone which is an example of an information processing apparatus in which the imaging optical system of the present invention is incorporated as a photographing optical system, particularly a portable telephone which is convenient to carry. 25A is a front view of the mobile phone 400, FIG. 25B is a side view, and FIG. 25C is a cross-sectional view of the photographing optical system 405. As shown in FIGS. 25A to 25C, the mobile phone 400 includes a microphone unit 401, a speaker unit 402, an input dial 403, a monitor 404, a photographing optical system 405, an antenna 406, and processing. Means.

  Here, the microphone unit 401 is for inputting an operator's voice as information. The speaker unit 402 is for outputting the voice of the other party. An input dial 403 is used by an operator to input information. The monitor 404 is for displaying information such as a photographed image of the operator himself or the other party, a telephone number, and the like. The antenna 406 is for transmitting and receiving communication radio waves. The processing means (not shown) is for processing image information, communication information, input signals, and the like.

  Here, the monitor 404 is a liquid crystal display element. In the drawing, the arrangement positions of the respective components are not particularly limited to these. The photographing optical system 405 includes the objective optical system 100 disposed on the photographing optical path 407 and an electronic image sensor chip 162 that receives an object image. As the objective optical system 100, for example, the zoom lens of Example 1 is used. These are built in the mobile phone 400.

A cover glass 102 for protecting the objective optical system 100 is disposed at the tip of the mirror frame.
The object image received by the electronic imaging element chip 162 is input to an image processing unit (not shown) via the terminal 166. Finally, the object image is displayed as an electronic image on the monitor 404, the monitor of the communication partner, or both. The processing means includes a signal processing function. When transmitting an image to a communication partner, this function converts information on the object image received by the electronic image sensor chip 162 into a signal that can be transmitted.

  The present invention can take various modifications without departing from the spirit of the present invention.

As described above, according to the present invention, the first lens unit includes only one lens component in which three lenses, one negative lens and two positive lenses, are cemented with each other. Thereby, the first lens group can be made thin while suppressing chromatic aberration occurring in the first lens group.
In addition, the amount of change in the distance between the first lens group and the second lens group from the wide-angle end to the telephoto end is smaller than the thickness of the lens groups of the first lens group and the second lens group. For this reason, it is possible to shorten the total length of the optical system at the telephoto end while satisfactorily correcting astigmatism and coma.
Further, the above-described fluctuation amount is small with respect to the zoom ratio. For this reason, even in a zoom optical system with a high zoom ratio, the total length of the optical system at the telephoto end can be shortened.
Further, the above-described fluctuation amount is small with respect to the maximum angle of view. For this reason, even in an optical system having a large maximum angle of view, the overall length of the optical system can be shortened.
As described above, according to the imaging optical system of the present invention, the total length of the optical system and the collapsed thickness can be shortened without deteriorating chromatic aberration.

  As described above, the present invention is useful for increasing the zoom ratio, reducing the thickness and improving the performance of the imaging optical system, and reducing the thickness of the electronic imaging apparatus.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group L1-L9 Each lens F, LPF Low pass filter C, CG Cover glass I Imaging surface E Eyeball of observer 40 Digital Camera 41 Shooting optical system 42 Shooting optical path 43 Viewfinder optical system 44 Viewfinder optical path 45 Shutter 46 Flash 47 LCD monitor 48 Zoom lens 49 CCD
DESCRIPTION OF SYMBOLS 50 Image pick-up surface 51 Processing means 53 Finder objective optical system 55 Porro prism 57 Field frame 59 Eyepiece optical system 66 Focusing lens 67 Imaging surface 100 Objective optical system 102 Cover glass 162 Electronic image pick-up element chip | tip 166 Terminal 300 Personal computer 301 Keyboard 302 Monitor 303 Imaging Optical System 304 Imaging Optical Path 305 Image 400 Mobile Phone 401 Microphone Unit 402 Speaker Unit 403 Input Dial 404 Monitor 405 Imaging Optical System 406 Antenna 407 Imaging Optical Path

Claims (11)

Including a plurality of lens groups,
The plurality of lens groups, in order from the object side,
A first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; and a final lens group.
During zooming, the distance between adjacent lens groups changes,
The final lens group has a positive refractive power;
The first lens group consists of only one cemented lens component,
The cemented lens component is composed of one negative lens and two positive lenses joined together,
The following conditional expression (1) is satisfied,
The third lens group has only two single lenses, a positive lens and a negative lens,
An imaging optical system in which the negative lens satisfies the following conditional expression (5).
0.05 <ΔD12 / ((ΣD1 + ΣD2) × γ × tan ω) <0.19 (1)
2 <SF3 <10 (5)
here,
ΔD12 is represented by | D12T-D12W |
D12W is the distance between the first lens group and the second lens group at the wide-angle end,
D12T is the distance between the first lens group and the second lens group at the telephoto end,
ΣD1 is the thickness of the first lens group,
ΣD2 is the thickness of the second lens group,
γ is a zoom ratio from the wide-angle end to the telephoto end of the imaging optical system,
ω is the maximum angle of view,
SF3 is a shaping factor of the negative lens of the third lens group, and the shaping factor is a value defined by the following equation:
SF3 = (r31 + r32) / (r31-r32)
r31 is the radius of curvature of the object side surface of the negative lens of the third lens group;
r32 is the radius of curvature of the image side surface of the negative lens of the third lens group;
It is. The imaging optical system according to claim 1, wherein the negative lens satisfies the following conditional expression (5 ″).
3 <SF3 <10 (5 '')
here,
SF3 is a shaping factor of the negative lens of the third lens group, and the shaping factor is a value defined by the following equation:
SF3 = (r31 + r32) / (r31-r32)
r31 is the radius of curvature of the object side surface of the negative lens of the third lens group;
r32 is the radius of curvature of the image side surface of the negative lens of the third lens group;
It is. The imaging optical system according to claim 1, wherein the following conditional expression (2) is satisfied.
-0.8 <ΔV2 / ΔV1 <0.8 (2)
here,
ΔV1 is represented by | V1W-V1T |
V1W is the position of the first lens group at the wide-angle end,
V1T is the position of the first lens group at the telephoto end,
ΔV2 is represented by | V2W-V2T |
V2W is the position of the second lens group at the wide-angle end,
V2T is the position of the second lens group at the telephoto end,
The sign is positive when each lens group is located on the object side at the telephoto end with respect to the position at the wide-angle end. The imaging optical system according to claim 1, wherein the following conditional expression (3) is satisfied.
-0.3 <ΔVL / fw <0.6 (3)
here,
ΔVL is represented by | VLW-VLT |
VLW is the position of the last lens group at the wide-angle end,
VLT is the position of the last lens group at the telephoto end,
fw is the focal length of the entire imaging optical system at the wide-angle end,
The sign is positive when the final lens group is located on the object side at the telephoto end with respect to the position at the wide-angle end.   5. The imaging optical system according to claim 1, wherein at least one of the cemented surfaces of the cemented lens component is an aspheric surface.   6. The imaging optical system according to claim 5, wherein two positive lenses in the cemented lens component are arranged adjacent to each other, and a cemented surface of the two positive lenses is an aspherical surface. The imaging optical system according to claim 6, wherein the following conditional expression (4) is satisfied.
0.0005 <| (P0−Ph) / P0 | <0.3 (4)
here,
P0 is the power on the optical axis of the joint surface,
Ph is the local power at the beam height h of the joint surface,
The ray height h is the ray height at which the absolute value of the difference between the local power of the joint surface and the power on the optical axis is maximized. The last lens group consists of one positive lens,
The imaging optical system according to claim 1, wherein the positive lens satisfies the following conditional expression (6).
-5 <SFL <0 (6)
here,
SFL is a shaping factor of the positive lens of the final lens group, and the shaping factor is a value defined by the following equation:
SFL = (rL1 + rL2) / (rL1-rL2))
rL1 is the radius of curvature of the object side surface of the positive lens in the last lens group,
rL2 is the radius of curvature of the image side surface of the positive lens in the last lens group,
It is. The imaging optical system according to any one of claims 1 to 8, wherein the cemented lens component satisfies the following conditional expression (7).
2 <f1T1 / f1 <15 (7)
here,
f1 is the focal length of the entire cemented lens component,
f1T1 is the focal length of the positive lens located on the object side, out of the two positive lenses included in the cemented lens component,
It is. The imaging optical system according to claim 1, wherein the following conditional expression (8) is satisfied.
0.60 <θgFT1 <0.80 (8)
here,
θgFT1 is the partial dispersion ratio (ngT1−nFT1) / (nFT1−nCT1) of the positive lens located on the object side of the two positive lenses included in the cemented lens component,
nCT1, nFT1, and ngT1 are refractive indexes of C-line, F-line, and g-line of the positive lens located on the object side,
It is.   An electronic imaging apparatus comprising the imaging optical system according to claim 1 and an electronic imaging device.

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