JP2011033895A - Variable magnification optical system and image pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable magnification optical system that properly corrects aberration while the entire length is reduced relative to an image height. <P>SOLUTION: The variable optical system with a variable power ratio of 2.5 or more includes, in order from the object side, at least a first lens group of negative refractive power and a second lens group of positive refractive power, and satisfies the following conditional expressions (1) and (2): (1) 0.44≤¾fv¾/(fw×ft)<SP>1/2</SP>≤0.61 and (2) 0.5≤¾fv¾/(fw×ft)<SP>1/2</SP>≤1.05, wherein fv is the focal distance of the lens group having a variable power action, f1 is the focal distance of the first lens group, fw is the focal distance of the optical system at a wide angle end, and ft is the focal distance of the optical system at a telephoto end. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a variable magnification optical system in which aberrations are corrected satisfactorily while reducing the overall length relative to the image height, and an imaging apparatus having the same.

  In recent years, digital cameras including solid-state imaging devices such as CCD (Charge Coupled Device) and CMOS (Complementary Metal-Oxide Semiconductor) have become mainstream instead of silver salt film cameras. There are various types of digital cameras, from high-functional types for business use to compact popular types.

  Among them, the compact popular type digital camera has been reduced in size due to the user's desire to enjoy photographing easily. As a result, digital cameras that are easy to carry and have good storage in clothes and bag pockets have appeared.

  Therefore, a further reduction in size is required for the variable magnification optical system employed in such a digital camera. However, not only a small size but also a high optical performance (a good correction of aberration) has been demanded.

  As a variable magnification optical system satisfying such a requirement, there is a variable magnification optical system disclosed in Patent Document 1. Patent Document 1 is a small optical system having a zoom ratio of about 3.

Japanese Patent Laid-Open No. 2005-173312

  However, it is difficult to say that the optical system disclosed in Patent Document 1 achieves both a reduction in the overall length (shortening) as compared with the image height and a good optical performance.

  The present invention has been made in view of such problems of the prior art, and has a variable magnification optical system in which aberrations are favorably corrected while reducing the overall length compared to the image height, and the same. An object is to provide an imaging device. Note that reducing the total length compared to the image height means that the value of (optical total length) / (image height) is small.

In order to solve the above problems, a variable magnification optical system according to the present invention is a variable magnification optical system having a variable magnification ratio of 2.5 or more, and a first lens group having negative refractive power in order from the object side. And a second lens group having a positive refractive power, and satisfying the following conditional expressions (1) and (2):
0.44 ≦ | fv | / (fw · ft) ^1/2 ≦ 0.61 (1)
0.5 ≦ | f1 | / (fw · ft) ^1/2 ≦ 1.05 (2)
However,
fv is a focal length of a lens group having a main zooming effect,
f1 is the focal length of the first lens group,
fw is the focal length of the variable magnification optical system at the wide-angle end,
ft is the focal length of the variable magnification optical system at the telephoto end,
It is.

  In the variable magnification optical system of the present invention, in order from the object side, the first lens group, the second lens group, a third lens group having a negative refractive power, and a first lens having a positive refractive power. It is preferable that the lens unit is composed of four lens groups.

In the variable magnification optical system of the present invention, it is preferable that the second lens group has a meniscus shape having a convex shape on the object side as a whole, and satisfies the following conditional expression (3).
−0.6 ≦ (Ra2−Rb2) / (Ra2 + Rb2) ≦ 0.2 (3)
However,
Ra2 is the radius of curvature of the surface closest to the object side of the second lens group,
Rb2 is the radius of curvature of the surface closest to the image plane of the second lens group,
It is.

In the zoom optical system of the present invention, the lens group having the main zooming action includes at least one lens having a negative refractive power and a lens having a positive refractive power, and the following conditional expression: It is preferable to satisfy (4).
0.015 ≦ | 1 / Vmin−1 / Vmax | ≦ 0.03 (4)
However,
Vmax is the largest Abbe number among the Abbe numbers of the lenses included in the lens group having the main zooming effect,
Vmin is the smallest Abbe number among the Abbe numbers of the lenses included in the lens group having the main zooming action,
The Abbe number is represented by (nd-1) / (nF-nC),
nd, nC, and nF are the refractive indexes of the d-line, C-line, and F-line,
It is.

The image pickup apparatus of the present invention includes a zoom optical system having a zoom ratio of 2.5 or more and an electronic image sensor disposed on the most image side of the zoom optical system. In order from the side, the lens group includes at least a first lens group having a negative refractive power and a second lens group having a positive refractive power. The lens group having a main zooming function includes at least one convex lens and one concave lens. And satisfying the following conditional expression (4), conditional expression (5) and conditional expression (6).
0.015 ≦ | 1 / Vmin−1 / Vmax | ≦ 0.03 (4)
0.2 ≦ | fv | /IH≦1.5 (5)
1.0 ≦ | f1 | /IH≦2.7 (6)
However,
fv is a focal length of the lens group having the main zooming effect,
f1 is the focal length of the first lens group,
IH is the image height of the image sensor,
Vmax is the largest Abbe number among the Abbe numbers of the lenses included in the lens group having the main zooming effect,
Vmin is the smallest Abbe number among the Abbe numbers of the lenses included in the lens group having the main zooming action,
The Abbe number is represented by (nd-1) / (nF-nC),
nd, nC, and nF are the refractive indexes of the d-line, C-line, and F-line,
It is.

  In the image pickup apparatus of the present invention, the zoom optical system includes, in order from the object side, the first lens group, the second lens group, a third lens group having negative refractive power, and a positive It is preferable that the lens unit includes a fourth lens group having a refractive power.

In the imaging apparatus of the present invention, it is preferable that the second lens group has a meniscus shape having a convex shape on the object side in the entire group, and satisfies the following conditional expression (3).
−0.6 ≦ (Ra2−Rb2) / (Ra2 + Rb2) ≦ 0.2 (3)
However,
Ra2 is the radius of curvature of the surface closest to the object side of the second lens group,
Rb2 is the radius of curvature of the surface closest to the image plane of the second lens group,
It is.

  According to the variable magnification optical system of the present invention, there is provided a variable magnification optical system in which aberrations are favorably corrected while reducing the overall length as compared with the image height, and an imaging apparatus having the same. be able to.

It is a lens sectional view of Example 1 of the variable magnification optical system concerning the present invention. FIG. 4 is an aberration diagram for focusing at infinity according to Example 1, where (a) shows a state at the wide-angle end, (b) shows an intermediate state, and (c) shows a state at the telephoto end. FIG. 3A is a diagram of aberrations at close focus according to Example 1, where (a) shows a state at the wide-angle end, (b) shows an intermediate state, and (c) shows a state at the telephoto end. FIG. 4 is a coma aberration diagram of Example 1, wherein (a) shows a state at the wide-angle end, (b) shows an intermediate state, and (c) shows a state at the telephoto end. It is a lens sectional view of Example 2 of the variable magnification optical system concerning the present invention. FIG. 5A is an aberration diagram for focusing at infinity according to Example 2, where (a) illustrates a state at the wide-angle end, (b) illustrates an intermediate state, and (c) illustrates a state at the telephoto end. FIG. 6A is an aberration diagram for Example 2 when focusing on the close-up. (A) shows a state at the wide-angle end, (b) shows an intermediate state, and (c) shows a state at the telephoto end. FIG. 6 is a 70% image high coma aberration diagram of Example 2, wherein (a) shows a state at the wide angle end, (b) shows an intermediate state, and (c) shows a state at the telephoto end. FIG. 6 is a lens cross-sectional view of a third example of the variable magnification optical system according to the present invention. FIG. 4A is an aberration diagram for focusing at infinity according to Example 3, where (a) illustrates a state at the wide angle end, (b) illustrates an intermediate state, and (c) illustrates a state at the telephoto end. FIG. 6A is an aberration diagram for Example 3 with close focus; (a) shows the state at the wide-angle end, (b) shows the middle, and (c) shows the state at the telephoto end. FIG. 7 is a 70% image high coma aberration diagram of Example 3, wherein (a) shows a state at the wide-angle end, (b) shows an intermediate state, and (c) shows a state at the telephoto end. FIG. 9 is a lens cross-sectional view of a fourth example of the variable magnification optical system according to the present invention. FIG. 6A is an aberration diagram for focusing at infinity according to Example 4, wherein (a) shows the state at the wide-angle end, (b) shows the middle, and (c) shows the state at the telephoto end. FIG. 6 is a 70% image high coma aberration diagram of Example 4, wherein (a) shows the state at the wide-angle end, (b) shows the middle, and (c) shows the state at the telephoto end. FIG. 10 is a lens cross-sectional view of a fifth example of the variable magnification optical system according to the present invention. FIG. 6A is an aberration diagram for focusing at infinity according to Example 5, where (a) illustrates a state at the wide-angle end, (b) illustrates an intermediate state, and (c) illustrates a state at the telephoto end. 7 is a 70% image high coma aberration diagram of Example 5, wherein (a) shows a state at the wide-angle end, (b) shows an intermediate state, and (c) shows a state at the telephoto end. FIG. 10 is a lens cross-sectional view of Example 6 of the variable magnification optical system according to the present invention. FIG. 7A is an aberration diagram for focusing at infinity according to Example 6, wherein (a) illustrates a state at the wide angle end, (b) illustrates an intermediate state, and (c) illustrates a state at the telephoto end. 7 is a 70% image high coma aberration diagram of Example 6, wherein (a) shows the state at the wide-angle end, (b) shows the middle, and (c) shows the state at the telephoto end. It is a lens sectional view of Example 7 of the variable magnification optical system concerning the present invention. FIG. 10A is an aberration diagram at the infinite distance in Example 7, where (a) shows a state at the wide-angle end, (b) shows an intermediate state, and (c) shows a state at the telephoto end. FIG. 7 is a 70% image high coma aberration diagram of Example 7, wherein (a) shows the state at the wide-angle end, (b) shows the middle, and (c) shows the state at the telephoto end. It is a lens sectional view of Example 8 of the variable magnification optical system concerning the present invention. FIG. 9A is an aberration diagram at the infinite focus in Example 8, where (a) shows a state at the wide angle end, (b) shows an intermediate state, and (c) shows a state at the telephoto end. FIG. 9 is a 70% image high coma aberration diagram of Example 8, wherein (a) shows the state at the wide-angle end, (b) shows the middle, and (c) shows the state at the telephoto end. It is a lens sectional view of Example 9 of the variable magnification optical system concerning the present invention. FIG. 10A is an aberration diagram of Example 9 when focusing on infinity, where (a) shows the wide-angle end, (b) shows the middle, and (c) shows the state at the telephoto end. It is a 70% image high coma aberration diagram of Example 9, (a) shows the state at the wide-angle end, (b) the middle, and (c) shows the state at the telephoto end. It is a front perspective view which shows the external appearance of the digital camera incorporating the variable magnification optical system of this invention. FIG. 32 is a rear perspective view showing the appearance of the digital camera shown in FIG. 31. FIG. 32 is a perspective view schematically showing the configuration of the digital camera shown in FIG. 31.

Prior to the description of the examples, the effects of the variable magnification optical system of the present embodiment will be described.
The variable magnification optical system of the present embodiment is a variable magnification optical system having a variable magnification ratio of 2.5 or more, and has a first lens group having negative refractive power and a positive refractive power in order from the object side. And at least a second lens group, and satisfy the following conditional expressions (1) and (2).
0.44 ≦ | fv | / (fw · ft) ^1/2 ≦ 0.61 (1)
0.5 ≦ | f1 | / (fw · ft) ^1/2 ≦ 1.05 (2)
However,
fv is a focal length of a lens group having a main zooming effect,
f1 is the focal length of the first lens group,
fw is the focal length of the variable magnification optical system at the wide-angle end,
ft is the focal length of the variable magnification optical system at the telephoto end,
It is.

  By increasing the refractive power of the first lens group, the position of the image (virtual image) formed by the first lens group can be brought closer to the image plane side. In addition, since the refractive power of the lens group having the main zooming action is sufficiently strong, the amount of movement of the lens group during zooming can be reduced. However, when the refractive power of the first lens group and the refractive power of the lens group having the main zooming function are increased, it is generally difficult to correct various aberrations, particularly spherical aberration and coma fluctuation during zooming. Become.

  Therefore, it is preferable that the refractive powers of the first lens group and the main zooming group satisfy the conditional expressions (1) and (2). If these conditional expressions are satisfied, it is possible to realize an optical system having a short overall length and in which various aberrations, in particular, spherical aberration at the time of zooming and coma aberration fluctuations are well corrected.

If the lower limit of conditional expression (1) is not reached, fluctuations in spherical aberration and coma increase during zooming, which is not desirable. On the other hand, exceeding the upper limit value of conditional expression (1) is undesirable because it causes an increase in the amount of movement of the lens unit during zooming.
If the lower limit of conditional expression (2) is not reached, spherical aberration and coma increase at the time of zooming, which is not desirable. On the other hand, exceeding the upper limit value of conditional expression (2) is not desirable because it becomes difficult to bring the position of the image (virtual image) formed by the first lens group closer to the image plane side.

Further, it is preferable that the following conditional expressions (1 ′) and (2 ′) are satisfied instead of the conditional expressions (1) and (2), respectively.
0.44 ≦ | fv | / (fw · ft) ^1/2 ≦ 0.55 (1 ′)
0.7 ≦ | f1 | / (fw · ft) ^1/2 ≦ 1.02 (2 ′)

  If the conditional expressions (1 ′) and (2 ′) are satisfied, the aberration can be corrected well while the total length of the optical system is further reduced (shortened) compared to the image height.

  In the variable magnification optical system of the present embodiment, preferably, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens having a negative refractive power. The lens group includes a fourth lens group having a positive refractive power.

  In the zoom optical system of the present embodiment, preferably, the first lens group is fixed at the time of zooming from the wide-angle end to the telephoto end or at the time of shooting from infinite shooting to close-up shooting.

  If the first lens unit is fixed at the time of zooming, the entire length of the optical system is also fixed. By doing so, it is possible to easily secure the strength of the lens frame. As a result, the configuration of the lens frame can be simplified, and the optical system can be downsized.

  In the variable magnification optical system of the present embodiment, preferably, the first lens group includes two or less lens components.

  In order to realize a small optical system, it is preferable that the number of constituent members of each group be small. In order to reduce the size while favorably correcting aberrations, it is desirable that the first lens group is composed of at most two lenses.

  In the zoom optical system of the present embodiment, preferably, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens having a negative refractive power. The first lens group and the fourth lens group are composed of a lens group and a fourth lens group having a positive refractive power, and at the time of zooming from the wide-angle end to the telephoto end or shooting from infinite shooting to close-up shooting. Is fixed.

  By fixing the fourth lens group, the movable group is only the second lens group and the third lens group. In this case, the lens frame structure can be simplified, and thus the size can be reduced. Further, since the fixed group is disposed on the object side and the image plane side of the two movable groups, it is possible to reduce aberration fluctuations during zooming. As a result, it is possible to reduce the size of the optical system while maintaining good optical performance in all states (wide-angle end to telephoto end, infinite shooting to close-up shooting).

In the zoom optical system according to the present embodiment, it is preferable that the second lens group has a meniscus shape having a convex shape on the object side in the entire group, and satisfies the following conditional expression (3).
−0.6 ≦ (Ra2−Rb2) / (Ra2 + Rb2) ≦ 0.2 (3)
However,
Ra2 is the radius of curvature of the most object side surface of the second lens group,
Rb2 is the radius of curvature of the surface closest to the image plane of the second lens group,
It is.

  The second lens group preferably has a meniscus shape that is convex toward the object side in the entire group. By doing so, the principal point position can be located closer to the object side at the telephoto end. As a result, it becomes easy to perform a large zooming with a small amount of movement. Further, it is possible to shorten the overall length of the optical system and to satisfactorily correct various aberrations, in particular, variations in spherical aberration and coma during zooming.

  If the lower limit of conditional expression (3) is not reached, it is difficult to obtain a sufficient zoom ratio, which is not desirable. Exceeding the upper limit value of conditional expression (3) is not desirable because fluctuations in spherical aberration and coma increase during zooming.

Moreover, it is preferable that the following conditional expression (3 ′) is satisfied instead of conditional expression (3).
−0.45 ≦ (Ra2−Rb2) / (Ra2 + Rb2) ≦ 0.05 (3 ′)

  When the conditional expression (3 ′) is satisfied, the optical system can be more effectively downsized.

In the zoom optical system of the present embodiment, preferably, the lens group having a main zooming action includes at least one lens having a negative refractive power and a lens having a positive refractive power, and the following conditions are satisfied. Formula (4) is satisfied.
0.015 ≦ | 1 / Vmin−1 / Vmax | ≦ 0.03 (4)
However,
Vmax is the largest Abbe number among the Abbe numbers of the lenses included in the lens group having the main zooming effect,
Vmin is the smallest Abbe number among the Abbe numbers of the lenses included in the lens group having the main zooming action.
The Abbe number is represented by (nd-1) / (nF-nC),
nd, nC, and nF are the refractive indexes of the d-line, C-line, and F-line,
It is.

  The lens group having a main zooming function preferably includes at least one convex lens and one concave lens. In this way, the overall length of the optical system can be reduced, and various aberrations, particularly axial chromatic aberration can be favorably corrected from the wide-angle end to the telephoto end.

  If the lower limit of conditional expression (4) is not reached, aberration correction will be insufficient, which is not desirable. On the other hand, exceeding the upper limit value of conditional expression (4) is not desirable because axial chromatic aberration is overcorrected.

Moreover, it is preferable to satisfy the following conditional expression (4 ′) instead of conditional expression (4).
0.017 ≦ | 1 / Vmin−1 / Vmax | ≦ 0.028 (4 ′)

  When conditional expression (4 ') is satisfied, axial chromatic aberration can be corrected more satisfactorily. Therefore, the overall length of the optical system can be reduced while maintaining good performance.

In addition, the imaging apparatus of the present embodiment includes a zoom optical system having a zoom ratio of 2.5 or more and an electronic image sensor disposed on the most image side of the zoom optical system. In order, the first lens group having a negative refractive power and the second lens group having a positive refractive power include at least one or more convex lenses and concave lenses. The following conditional expression (4), conditional expression (5), and conditional expression (6) are satisfied.
0.015 ≦ | 1 / Vmin−1 / Vmax | ≦ 0.03 (4)
0.2 ≦ | fv | /IH≦1.5 (5)
1.0 ≦ | f1 | /IH≦2.7 (6)
However,
fv is a focal length of a lens group having a main zooming effect,
f1 is the focal length of the first lens group,
IH is the image height of the image sensor,
Vmax is the largest Abbe number among the Abbe numbers of the lenses included in the lens group having the main zooming effect,
Vmin is the smallest Abbe number among the Abbe numbers of the lenses included in the lens group having the main zooming action.
The Abbe number is represented by (nd-1) / (nF-nC),
nd, nC, and nF are the refractive indexes of the d-line, C-line, and F-line,
It is.

  When conditional expressions (4), (5) and (6) are satisfied, an optical system is realized in which the total length is short and various aberrations, in particular, spherical aberration, coma and axial chromatic aberration during zooming are well corrected. Is possible. In conditional expressions (5) and (6), IH is the image height of the image sensor, but more specifically, IH is half the diagonal length on the image plane of the image sensor. The height of the image formed on the image sensor (distance from the optical axis to the maximum image height) may be used as IH.

Conditional expression (4) is as described above.
If the lower limit of conditional expression (5) is not reached, fluctuations in spherical aberration and coma increase during zooming, which is not desirable. On the other hand, exceeding the upper limit of conditional expression (5) is not desirable because it causes an increase in the amount of movement of the lens unit during zooming.
If the lower limit of conditional expression (6) is not reached, spherical aberration and coma increase at the time of zooming, which is not desirable. On the other hand, exceeding the upper limit value of conditional expression (6) is not desirable because it becomes difficult to bring the position of the image (virtual image) formed by the first lens group closer to the image plane side.

Further, it is preferable that the following conditional expressions (4 ′), (5 ′) and (6 ′) are satisfied instead of the conditional expressions (4), (5) and (6).
0.017 ≦ | 1 / Vmin−1 / Vmax | ≦ 0.028 (4 ′)
0.8 ≦ | fv | /IH≦1.45 (5 ′)
1.8 ≦ | f1 | /IH≦2.65 (6 ′)

  When the conditional expressions (4 ′), (5 ′) and (6 ′) are satisfied, it is possible to correct aberrations satisfactorily while further reducing the overall length of the optical system as compared with the image height. it can.

  In the imaging apparatus of the present embodiment, the variable magnification optical system preferably includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a negative The lens unit includes a third lens group having a refractive power and a fourth lens group having a positive refractive power.

  In the imaging apparatus of the present embodiment, the first lens group is preferably fixed at the time of zooming from the wide angle end to the telephoto end or at the time of shooting from infinite shooting to close-up shooting.

  The function and effect of configuring the variable magnification optical system in this way are as described above.

  In the imaging apparatus according to the present embodiment, preferably, the first lens group includes two or less lens components.

  The effects of configuring the first lens group in this way are as described above.

  In the imaging apparatus according to the present embodiment, the variable magnification optical system preferably includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a negative The third lens group having a refractive power and the fourth lens group having a positive refractive power, the first lens at the time of zooming from the wide-angle end to the telephoto end or shooting from infinite shooting to close-up shooting The group and the fourth lens group are fixed.

  The function and effect of configuring the variable magnification optical system in this way are as described above.

In the imaging apparatus of this embodiment, it is preferable that the second lens group has a meniscus shape having a convex shape on the object side in the entire group, and satisfies the following conditional expression (3).
−0.6 ≦ (Ra2−Rb2) / (Ra2 + Rb2) ≦ 0.2 (3)
However,
Ra2 is the radius of curvature of the most object side surface of the second lens group,
Rb2 is the radius of curvature of the surface closest to the image plane of the second lens group,
It is.

Moreover, it is preferable that the following conditional expression (3 ′) is satisfied instead of conditional expression (3).
−0.45 ≦ (Ra2−Rb2) / (Ra2 + Rb2) ≦ 0.05 (3 ′)

  The operational effects and the conditional expressions (3) and (3 ') that constitute the second lens group in this way are as described above.

Examples 1 to 9 using the variable magnification optical system of the present embodiment will be described below.
FIG. 1 is a sectional view of the variable magnification optical system of Example 1, FIG. 5 is a sectional view of the variable magnification optical system of Example 2, FIG. 9 is a sectional view of the variable magnification optical system of Example 3, and FIG. 13 is a cross-sectional view of the variable power optical system 4, FIG. 16 is a cross-sectional view of the variable power optical system of Example 5, FIG. 19 is a cross-sectional view of the variable power optical system of Example 6, and FIG. FIG. 22 is a cross-sectional view of the variable power optical system, FIG. 25 is a cross-sectional view of the variable power optical system of Example 8, and FIG. 28 is a cross-sectional view of the variable power optical system of Example 9. In each figure, (a) shows the state at the wide-angle end, (b) shows the state at the middle, and (c) shows the state at the telephoto end.

In the following examples, Examples 1 to 7 have an image height of 2.9 mm and the pixel pitch of the image sensor is 1.4 μm, and Examples 8 and 9 have an image height of 2.25 mm and the pixel pitch of the image sensor. Although it is 1.4 μm, the pixel pitch may be 2.00 μm and 1.75 μm in any of the embodiments.
The aperture stop diameter at the telephoto end is larger than the aperture stop diameter at the wide angle end. Thereby, at the telephoto end, it is possible to prevent a decrease in performance due to the diffraction limit. However, if there is no practical problem, the aperture diameter may be constant.

The optical configuration of the variable magnification optical system of the present embodiment will be described with reference to FIG. The variable magnification optical system of this example has a total length of 13 mm.
The variable magnification optical system of the present embodiment has a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a negative refractive power in order from the object side on the optical axis Lc. It has a third lens group G3 and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, and has a negative refractive power as a whole. is doing.

  The second lens group G2 includes, in order from the object side, a biconvex positive lens L21, an aperture stop S, a biconvex positive lens L22, and a biconcave negative lens L23 joined to the biconvex positive lens L22. It has a positive refractive power as a whole and has a main zooming action.

  The third lens group G3 is composed of one biconcave negative lens L3. The biconcave negative lens L3 may be a negative meniscus lens having a convex surface facing the object side, or a negative meniscus lens having a concave surface facing the object side.

  The fourth lens group G4 is composed of one positive meniscus lens L4 having a convex surface directed toward the image side.

When zooming from the wide-angle end to the telephoto end, the positions of the first lens group G1 and the fourth lens group G4 are fixed, and the second lens group G2 and the third lens group G3 move to the object side.
At the time of focusing from the object point at infinity to the closest object point, both the second lens group G2 and the third lens group G3 may be moved.

The optical configuration of the variable magnification optical system of the present embodiment will be described with reference to FIG. The variable magnification optical system of this example has a total length of 13 mm.
The variable magnification optical system of the present embodiment includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power in order from the object side. And a fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, and has a negative refractive power as a whole. is doing.

  The second lens group G2 includes, in order from the object side, a biconvex positive lens L21, an aperture stop S, a biconvex positive lens L22, and a biconcave negative lens L23 joined to the biconvex positive lens L22. It has a positive refractive power as a whole and has a main zooming action.

  The third lens group G3 is composed of one negative meniscus lens L3 having a concave surface directed toward the object side.

  The fourth lens group G4 is composed of one positive meniscus lens L4 having a convex surface directed toward the image side.

When zooming from the wide-angle end to the telephoto end, the positions of the first lens group G1 and the fourth lens group G4 are fixed, and the second lens group G2 and the third lens group G3 move to the object side.
At the time of focusing from the object point at infinity to the closest object point, both the second lens group G2 and the third lens group G3 may be moved.
By moving both groups, it is possible to satisfactorily correct the variation in field curvature during focusing.

The optical configuration of the variable magnification optical system of the present embodiment will be described with reference to FIG. The variable magnification optical system of the present example has a total length of 13.5 mm.
The variable magnification optical system of the present embodiment includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power in order from the object side. And a fourth lens group G4 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a biconcave negative lens L11, and a positive meniscus lens L12 having a convex surface facing the object side in a state of being joined to the biconcave negative lens L11. Has negative refractive power.
If L12 is an energy curable resin, the first lens group G1 can be processed thinly, and the amount of movement of the second lens group G2 during zooming can be secured sufficiently, so that the overall length is shortened while maintaining good performance. Is possible.

  The second lens group G2 includes, in order from the object side, a biconvex positive lens L21, an aperture stop S, a biconvex positive lens L22, and a biconcave negative lens L23 joined to the biconvex positive lens L22. , Has a positive refractive power as a whole.

  The third lens group G3 is composed of one biconcave negative lens L3.

  The fourth lens group G4 is composed of one positive meniscus lens L4 having a convex surface directed toward the image side.

When zooming from the wide-angle end to the telephoto end, the positions of the first lens group G1 and the fourth lens group G4 are fixed, the second lens group G2 moves to the object side, and the third lens group G3 is in the middle. Move to the most object side in position.
At the time of focusing from the object point at infinity to the closest object point, both the second lens group G2 and the third lens group G3 may be moved.
By moving both groups, it is possible to satisfactorily correct the variation in field curvature during focusing.

The optical configuration of the variable magnification optical system of the present embodiment will be described with reference to FIG. The variable magnification optical system of this example has a total length of 13 mm.
The variable magnification optical system of the present embodiment includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power in order from the object side. And a fourth lens group G4 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a biconcave negative lens L11, and a positive meniscus lens L12 having a convex surface facing the object side in a state of being joined to the biconcave negative lens L11. Has negative refractive power.
If L12 is an energy curable resin, the first lens group G1 can be processed thinly, and the amount of movement of the second lens group G2 during zooming can be secured sufficiently, so that the overall length is shortened while maintaining good performance. Is possible.

  The second lens group G2 includes, in order from the object side, a biconvex positive lens L21, an aperture stop S, a biconvex positive lens L22, and a biconcave negative lens L23 joined to the biconvex positive lens L22. It has a positive refractive power as a whole and has a main zooming action.

  The third lens group G3 is composed of one biconcave negative lens L3.

  The fourth lens group G4 is composed of one positive meniscus lens L4 having a convex surface directed toward the image side.

When zooming from the wide-angle end to the telephoto end, the positions of the first lens group G1 and the fourth lens group G4 are fixed, the second lens group G2 moves to the object side, and the third lens group G3 is in the middle. Move to the most object side in position.
At the time of focusing from the object point at infinity to the closest object point, both the second lens group G2 and the third lens group G3 may be moved.
By moving both groups, it is possible to satisfactorily correct the variation in field curvature during focusing.

The optical configuration of the variable magnification optical system of the present embodiment will be described with reference to FIG. The variable magnification optical system of this example has a total length of 13 mm.
The variable magnification optical system of the present embodiment includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power in order from the object side. And a fourth lens group G4 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a biconcave negative lens L11, and a positive meniscus lens L12 having a convex surface facing the object side in a state of being joined to the biconcave negative lens L11. Has negative refractive power.
If L12 is an energy curable resin, the first lens group G1 can be processed thinly, and the amount of movement of the second lens group G2 during zooming can be secured sufficiently, so that the overall length is shortened while maintaining good performance. Is possible.

  The second lens group G2 includes, in order from the object side, a biconvex positive lens L21, an aperture stop S, a biconvex positive lens L22, and a biconcave negative lens L23 joined to the biconvex positive lens L22. It has a positive refractive power as a whole and has a main zooming action.

  The third lens group G3 is composed of one negative meniscus lens L3 having a convex surface directed toward the object side.

  The fourth lens group G4 is composed of one positive meniscus lens L4 having a convex surface directed toward the image side.

  When zooming from the wide-angle end to the telephoto end, the positions of the first lens group G1 and the fourth lens group G4 are fixed, and the second lens group G2 and the third lens group G3 move to the object side.

The optical configuration of the variable magnification optical system of the present embodiment will be described with reference to FIG. The variable magnification optical system of the present example has a total length of 13.5 mm.
The variable magnification optical system of the present embodiment includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power in order from the object side. And a fourth lens group G4 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a biconcave negative lens L11, and a positive meniscus lens L12 having a convex surface facing the object side in a state of being joined to the biconcave negative lens L11. Has negative refractive power.
If L12 is an energy curable resin, the first lens group G1 can be processed thinly, and the amount of movement of the second lens group G2 during zooming can be secured sufficiently, so that the overall length is shortened while maintaining good performance. Is possible.

  The second lens group G2 includes, in order from the object side, a biconvex positive lens L21, an aperture stop S, a biconvex positive lens L22, and a biconcave negative lens L23 joined to the biconvex positive lens L22. It has a positive refractive power as a whole and has a main zooming action.

  The third lens group G3 is composed of one biconcave negative lens L3.

  The fourth lens group G4 is composed of one positive meniscus lens L4 having a convex surface directed toward the image side.

  When zooming from the wide-angle end to the telephoto end, the position of the first lens group G1 is fixed, the second lens group G2 moves to the object side, and the third lens group G3 moves to the most object side at the intermediate position. The fourth lens group G4 moves to the image side.

The optical configuration of the variable magnification optical system of the present embodiment will be described with reference to FIG. The variable magnification optical system of the present embodiment has a total length of 14 mm.
The variable magnification optical system of the present embodiment includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power in order from the object side. And a fourth lens group G4 having a positive refractive power.

  The first lens group G1 is composed of one biconcave negative lens L1.

  The second lens group G2 includes, in order from the object side, a biconvex positive lens L21, a biconcave negative lens L22 joined to the biconvex positive lens L21, an aperture stop S, and a biconvex positive lens L23. It has a positive refractive power as a whole and has a main zooming effect.

  The third lens group G3 is composed of one negative meniscus lens L3 having a convex surface directed toward the object side.

  The fourth lens group G4 is composed of one positive meniscus lens L4 having a convex surface directed toward the image side.

  When zooming from the wide-angle end to the telephoto end, the positions of the first lens group G1 and the fourth lens group G4 are fixed, and the second lens group G2 and the third lens group G3 move to the object side.

The optical configuration of the variable magnification optical system of the present embodiment will be described with reference to FIG. The variable magnification optical system of this example has a total length of 10.1 mm.
The variable magnification optical system of the present embodiment has a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a negative refractive power in order from the object side on the optical axis Lc. It has a third lens group G3 and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes, in order from the object side, a biconcave negative lens L11 and a positive meniscus lens L12 having a convex surface directed toward the object side, and has a negative refractive power as a whole.

  The second lens group G2 includes, in order from the object side, a biconvex positive lens L21, an aperture stop S, a biconvex positive lens L22, and a biconcave negative lens L23 joined to the biconvex positive lens L22. It has a positive refractive power as a whole and has a main zooming action.

  The third lens group G3 is composed of one biconcave negative lens L3.

  The fourth lens group G4 is composed of one positive meniscus lens L4 having a convex surface directed toward the image side.

When zooming from the wide-angle end to the telephoto end, the positions of the first lens group G1 and the fourth lens group G4 are fixed, and the second lens group G2 and the third lens group G3 move to the object side.
At the time of focusing from the object point at infinity to the closest object point, both the second lens group G2 and the third lens group G3 may be moved.

The optical configuration of the variable magnification optical system of the present embodiment will be described with reference to FIG. The variable magnification optical system of this example has a total length of 10.1 mm.
The variable magnification optical system of the present embodiment has a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a negative refractive power in order from the object side on the optical axis Lc. It has a third lens group G3 and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, and has a negative refractive power as a whole. is doing.

  The second lens group G2 includes, in order from the object side, a biconvex positive lens L21, an aperture stop S, a biconvex positive lens L22, and a biconcave negative lens L23 joined to the biconvex positive lens L22. It has a positive refractive power as a whole and has a main zooming action.

  The third lens group G3 is composed of one negative meniscus lens L3 having a convex surface directed toward the object side.

  The fourth lens group G4 is composed of one positive meniscus lens L4 having a convex surface directed toward the image side.

When zooming from the wide-angle end to the telephoto end, the positions of the first lens group G1 and the fourth lens group G4 are fixed, and the second lens group G2 and the third lens group G3 move to the object side.
At the time of focusing from the object point at infinity to the closest object point, both the second lens group G2 and the third lens group G3 may be moved.

Next, numerical data of optical members constituting the variable magnification optical system are shown for each of Examples 1 to 9. Example 1 corresponds to Numerical Example 1. Example 2 corresponds to Numerical Example 2. Example 3 corresponds to Numerical Example 3. Example 4 corresponds to Numerical Example 4. Example 5 corresponds to Numerical Example 5. Example 6 corresponds to Numerical Example 6. Example 7 corresponds to Numerical Example 7. Example 8 corresponds to Numerical Example 8. Example 9 corresponds to Numerical Example 9.
In numerical data and drawings, r is the radius of curvature of each lens surface, d is the thickness or air spacing of each lens, nd is the refractive index of each lens at the d-line (587.56 nm), and νd is the d of each lens. The Abbe number at the line (587.56 nm), * (asterisk) represents an aspherical surface. The unit of length is mm.

The aspherical shape is expressed by the following equation (I) where z is the optical axis direction, y is the direction orthogonal to the optical axis, K is the conic coefficient, and A4, A6, A8, and A10 are the aspheric coefficients. expressed.
^{z = (y 2 / r)} / [1+ {1- (1 + K) / (y / r) 2} 1/2] + A4y 4 + A6y 6 + A8y 8 + A10y 10 ... (I)
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
Surface data Unit mm

Surface number rd nd vd Effective diameter Surface ∞ ∞
1 * 29.7496 0.5421 1.90270 31.00 2.690
2 * 2.6180 0.5723 2.165
3 * 3.5600 0.7172 2.10223 16.77 2.185
4 * 5.6420 D4 2.097
5 * 2.1763 0.9187 1.59201 67.02 1.427
6 * -44.5379 0.2000 1.318
7 (Aperture) ∞ 0.0000 (Variable)
8 * 5.9838 0.6894 1.85135 40.10 1.207
9 -6.5431 0.5215 1.82114 24.06 1.137
10 * 5.0933 D10 1.011
11 * -4.9399 0.4461 1.77377 47.17 1.198
12 * 53.6530 D12 1.427
13 * -14.4249 0.8801 1.82114 24.06 2.808
14 * -5.0670 0.2353 2.868
15 ∞ 0.3000 1.51633 64.14 2.929
16 ∞ 0.4000 2.947
Image plane ∞

Aspheric data 1st surface
K = -224.489, A4 = 6.10008e-03, A6 = -1.22957e-03, A8 = 5.75218e-05
Second side
K = 0.086, A4 = -6.58139e-03, A6 = 3.39688e-03, A8 = -7.32903e-04
Third side
K = -6.605, A4 = -3.67877e-03, A6 = 1.95938e-03, A8 = -8.93682e-05
4th page
K = -21.342, A4 = -4.83678e-03, A6 = 6.39538e-04, A8 = 5.70942e-05
5th page
K = -0.989, A4 = 2.50732e-03, A6 = 7.21049e-04, A8 = 3.61962e-04
6th page
K = -791.631, A4 = -1.12792e-02, A6 = 8.93540e-03, A8 = -1.87646e-03
8th page
K = 4.845, A4 = -9.49342e-04, A6 = 9.01956e-03, A8 = -2.80204e-03
10th page
K = -32.788, A4 = 6.96684e-02, A6 = -4.68501e-03, A8 = 9.73012e-03
11th page
K = -3.112, A4 = 3.30281e-03, A6 = -6.05974e-03, A8 = -4.24602e-03
12th page
K = -40363.004, A4 = 2.29435e-02, A6 = -1.24625e-02, A8 = 9.19254e-04
Side 13
K = -1.394, A4 = 4.97914e-03, A6 = -1.14929e-03, A8 = 9.38867e-05
14th page
K = -2.722, A4 = 1.16889e-02, A6 = -2.73333e-03, A8 = 1.79573e-04

Various data

Zoom ratio 2.850

Wide angle Medium telephoto Wide angle (closest) Medium (closest) Telephoto (closest)

Focal length 3.754 6.025 10.699
FNO. 3.200 4.369 5.200
Angle of view 2ω 82.828 51.090 29.527
Image height 2.900 2.900 2.900
BF 0.833 0.833 0.833
Total lens length 12.898 12.898 12.898

Object distance ∞ ∞ ∞ 100.00 500.00 800.00
D4 3.941 2.207 0.200 3.225 2.257 0.483
D10 1.025 0.863 1.714 0.969 0.883 1.519
D12 1.611 3.507 4.664 2.384 3.438 4.575

Diaphragm diameter 0.987 0.987 1.215
Entrance pupil position 3.159 2.655 1.791
Exit pupil position -6.368 -14.458 -35.576
Front principal point position 4.966 6.304 9.349
Rear principal point position -3.317 -5.641 -10.271

Lens Start surface Focal length
L11 1 -3.210
L12 3 7.413
L21 5 3.531
L22 8 3.767
L23 9 -3.419
L3 11 -5.827
L4 13 9.125

Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 -5.731 1.832 0.276 -0.873
G2 5 3.191 2.330 -0.304 -1.515
G3 11 -5.827 0.446 0.021 -0.230
G4 13 9.125 0.880 0.715 0.251

Group magnification
Wide angle Medium telephoto Wide angle (closest) Medium (closest) Telephoto (closest)
G1 0.000 0.000 0.000 0.054 0.011 0.007
G2 -0.453 -0.600 -0.964 -0.530 -0.602 -0.898
G3 1.553 1.868 2.075 1.689 1.859 2.063
G4 0.932 0.938 0.933 0.930 0.936 0.931

Numerical example 2
Surface data Unit mm

Surface number rd nd vd Effective diameter Surface ∞ ∞
1 * 31.1191 0.5500 1.85135 40.10 2.825
2 * 2.5330 0.5132 2.187
3 * 3.1051 0.8424 1.82114 24.06 2.203
4 * 5.5712 D4 2.110
5 * 2.0868 1.0720 1.59201 67.02 1.438
6 * -181.2845 0.2000 1.296
7 (Aperture) ∞ 0.0000 (Variable)
8 * 5.2934 0.6793 1.85135 40.10 1.161
9 -9.4008 0.4687 1.82114 24.06 1.086
10 * 4.3096 D10 0.980
11 * -4.5361 0.4000 1.77377 47.17 1.185
12 * -4863.2721 D12 1.405
13 * -15.0779 0.8960 1.82114 24.06 2.787
14 * -4.9623 0.2027 2.854
15 ∞ 0.3000 1.51633 64.14 2.920
16 ∞ 0.4000 2.953
Image plane ∞

Aspheric data 1st surface
K = 9.975, A4 = 5.45942e-03, A6 = -1.17913e-03, A8 = 6.14112e-05
Second side
K = 0.028, A4 = -5.92450e-03, A6 = 3.54360e-03, A8 = -7.18809e-04
Third side
K = -4.944, A4 = -2.93256e-03, A6 = 2.56724e-03, A8 = -1.52620e-04
4th page
K = -16.419, A4 = -5.87501e-03, A6 = 9.32666e-04, A8 = 4.10944e-05
5th page
K = -0.869, A4 = 3.97321e-03, A6 = 4.46620e-04, A8 = 3.23707e-04
6th page
K = -9645.985, A4 = -2.36383e-02, A6 = 1.14055e-02, A8 = -2.04346e-03
8th page
K = -2.017, A4 = -1.25319e-02, A6 = 1.04830e-02, A8 = -2.75134e-03
10th page
K = -37.283, A4 = 8.97816e-02, A6 = -2.64567e-02, A8 = 2.13844e-02
11th page
K = -3.217, A4 = 3.81585e-03, A6 = -1.49213e-02, A8 = 1.03508e-03
12th page
K = -14369395.106, A4 = 1.43170e-02, A6 = -1.10677e-02, A8 = 1.12467e-03
Side 13
K = -1.990, A4 = 5.00050e-03, A6 = -1.15848e-03, A8 = 9.16097e-05
14th page
K = -2.578, A4 = 1.16150e-02, A6 = -2.73641e-03, A8 = 1.80048e-04

Various data

Zoom ratio 2.850

Wide angle Medium telephoto Wide angle (closest) Medium (closest) Telephoto (closest)

Focal length 3.754 6.021 10.699
FNO. 3.200 4.384 5.200
Angle of view 2ω 82.691 50.978 29.424
Image height 2.900 2.900 2.900
BF 0.801 0.801 0.801
Total lens length 12.898 12.898 12.898
Object distance ∞ ∞ ∞ 100.00 500.00 800.00
D4 3.931 2.208 0.200 3.736 2.222 0.266
D10 0.964 0.788 1.612 0.981 0.811 1.598
D12 1.581 3.480 4.663 1.759 3.443 4.612
Diaphragm diameter 0.944 0.944 1.173
Entrance pupil position 3.288 2.795 1.956
Exit pupil position -6.289 -14.879 -41.689
Front principal point position 5.061 6.495 9.958
Rear principal point position -3.330 -5.679 -10.344

Lens Start surface Focal length
L11 1 -3.268
L12 3 7.403
L21 5 3.492
L22 8 4.064
L23 9 -3.544
L3 11 -5.868
L4 13 8.662

Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 -5.825 1.906 0.340 -0.873
G2 5 3.180 2.420 -0.387 -1.600
G3 11 -5.868 0.400 -0.000 -0.226
G4 13 8.662 0.896 0.705 0.232

Group magnification
Wide angle Medium telephoto Wide angle (closest) Medium (closest) Telephoto (closest)
G1 0.000 0.000 0.000 0.055 0.012 0.007
G2 -0.450 -0.596 -0.954 -0.486 -0.601 -0.948
G3 1.536 1.844 2.048 1.576 1.842 2.043
G4 0.932 0.941 0.940 0.926 0.939 0.938

Numerical Example 3
Surface data Unit mm

Surface number rd nd vd Effective diameter Surface ∞ ∞
1 * -20.7452 0.4261 1.76802 49.24 2.660
2 * 3.1798 0.5199 1.63387 23.38 2.348
3 * 11.5413 D3 2.338
4 * 2.5653 0.7836 1.69350 53.21 1.425
5 * -9.5581 0.1627 1.304
6 (Aperture) ∞ 0.1056 (Variable)
7 * 6.3829 0.6523 1.77377 47.17 1.173
8 -16.9084 0.3267 1.84666 23.78 1.048
9 * 2.6017 D9 0.900
10 * -1663.5639 0.3688 1.58913 61.14 1.798
11 * 9.0733 D11 1.796
12 * -6.3464 0.7403 1.82114 24.06 2.400
13 * -4.0025 2.2296 2.510
14 ∞ 0.3796 1.51633 64.14 2.909
15 ∞ 0.4000 2.942
Image plane ∞

Aspheric data 1st surface
K = -375.930, A4 = -1.15480e-02, A6 = 2.04009e-03, A8 = -2.03463e-04, A10 = 9.13064e-06
Second side
K = -4.767
Third side
K = 19.716, A4 = -8.39462e-03, A6 = 8.74090e-04, A8 = -3.16644e-05, A10 = -9.08607e-06
4th page
K = -5.335, A4 = 3.95944e-02, A6 = -2.26682e-04, A8 = 1.21738e-03, A10 = -2.20735e-05
5th page
K = -1.433, A4 = 5.93078e-02, A6 = -5.72481e-03, A8 = -1.00605e-05, A10 = -4.23420e-04
7th page
K = 0.827, A4 = 7.27634e-02, A6 = -2.04547e-02, A8 = 2.74787e-03, A10 = -2.76359e-03
9th page
K = 3.493, A4 = 2.51814e-02, A6 = -9.44244e-04, A8 = -9.17287e-03, A10 = -9.81182e-03
10th page
K = 0.000, A4 = 2.01378e-02, A6 = 2.42834e-03, A8 = -6.61110e-04, A10 = -3.37042e-05
11th page
K = 1.229, A4 = 2.32836e-02, A6 = 1.19434e-03, A8 = -5.32506e-05, A10 = -1.30308e-04
12th page
K = -0.983, A4 = 3.30959e-03, A6 = 1.23354e-04
Side 13
K = -1.651, A4 = -8.10707e-05, A6 = -7.42911e-05, A8 = 1.46926e-05

Various data

Zoom ratio 2.849

Wide angle Medium telephoto Wide angle (closest) Medium (closest) Telephoto (closest)

Focal length 4.521 7.640 12.880
FNO. 3.757 4.702 5.248
Angle of view 2ω 70.567 43.949 24.572
Image height 2.900 2.900 2.900
BF 2.880 2.880 2.880
Total lens length 13.374 13.371 13.371
Object distance ∞ ∞ ∞ 100.00 500.00 800.00
D3 4.604 2.224 0.151 3.959 2.507 0.265
D9 0.557 0.550 4.157 0.781 0.549 4.037
D11 1.247 3.631 2.097 1.665 3.348 2.102
Diaphragm diameter 0.900 1.000 1.250
Entrance pupil position 3.479 2.544 1.301
Exit pupil position -4.272 -11.074 -15.850
Front principal point position 5.143 6.001 5.324
Rear principal point position -4.121 -7.240 -12.480

Lens Start surface Focal length
L11 1 -3.562
L12 2 6.761
L21 4 2.996
L22 7 6.063
L23 8 -2.643
L3 10 -15.316
L4 12 11.553

Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 -7.332 0.946 0.301 -0.251
G2 4 4.054 2.031 -1.113 -1.816
G3 10 -15.316 0.369 0.231 -0.001
G4 12 11.553 3.349 0.963 -1.872

Group magnification
Wide angle Medium telephoto Wide angle (closest) Medium (closest) Telephoto (closest)
G1 0.000 0.000 0.000 0.068 0.014 0.009
G2 -0.578 -0.874 -1.579 -0.690 -0.842 -1.551
G3 1.329 1.485 1.385 1.356 1.466 1.385
G4 0.803 0.803 0.803 0.803 0.803 0.803

Numerical Example 4
Surface data Unit mm

Surface number rd nd vd Effective diameter Surface ∞ ∞
1 * -11.1356 0.4975 1.76802 49.24 2.436
2 * 4.3635 0.2782 1.68086 20.03 2.161
3 * 13.0403 D3 2.143
4 * 2.4354 1.1497 1.69350 53.21 1.500
5 * -10.2972 0.0965 1.338
6 (Aperture) ∞ 0.1122 (Variable)
7 * 6.9467 0.6344 1.76802 49.24 1.209
8 -10.0264 0.3871 1.84666 23.78 1.142
9 * 2.7369 D9 1.053
10 * -1593.9529 0.4096 1.58913 61.14 1.938
11 * 7.2355 D11 1.949
12 * -7.0449 1.0575 1.92286 20.88 2.686
13 * -3.9192 0.8750 2.866
14 ∞ 0.3796 1.51633 64.14 2.965
15 ∞ 0.4000 2.977
Image plane ∞

Aspheric data 1st surface
K = -43.263, A4 = -1.24712e-02, A6 = 1.73364e-03, A8 = -6.78483e-05
Second side
K = -13.143
Third side
K = 11.728, A4 = -8.61588e-03, A6 = 1.31833e-03, A8 = 3.44649e-05
4th page
K = -1.810, A4 = 1.47470e-02, A6 = 1.63827e-03, A8 = 1.52183e-04
5th page
K = 10.732, A4 = 1.76981e-02, A6 = -3.95829e-03, A8 = 3.18646e-04
7th page
K = -0.652, A4 = 6.62402e-03, A6 = -8.64488e-03, A8 = -8.05063e-04
9th page
K = 3.404, A4 = -4.48263e-03, A6 = -5.81944e-03, A8 = -5.86170e-03
10th page
K = 0.000, A4 = 6.85162e-03, A6 = 5.94218e-04
11th page
K = 1.002, A4 = 8.32696e-03, A6 = 6.31067e-04, A8 = -4.05088e-05
12th page
K = -4.931
Side 13
K = -3.651, A4 = -2.91002e-03, A6 = -8.23036e-05, A8 = -3.97711e-07

Various data

Zoom ratio 2.846

Wide angle Medium telephoto

Focal length 4.526 7.640 12.878
FNO. 3.590 5.050 5.131
Angle of view 2ω 72.782 43.815 24.659
Image height 2.900 2.900 2.900
BF1.525 1.525 1.525
Total lens length 12.867 12.873 12.875
Object distance ∞ ∞ ∞
D3 4.309 2.213 0.196
D9 1.296 1.055 4.311
D11 1.114 3.457 2.220
Diaphragm diameter 0.900 0.900 1.250
Entrance pupil position 3.292 2.510 1.389
Exit pupil position -7.123 -23.689 -42.013
Front principal point position 5.450 7.835 10.458
Rear principal point position -4.122 -7.242 -12.481

Lens Start surface Focal length
L11 1 -4.026
L12 2 9.508
L21 4 2.949
L22 7 5.431
L23 8 -2.505
L3 10 -12.225
L4 12 8.235

Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 -6.977 0.776 0.202 -0.239
G2 4 3.819 2.380 -1.106 -1.918
G3 10 -12.225 0.410 0.257 -0.001
G4 12 8.235 2.312 1.066 -0.532

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.579 -0.848 -1.536
G3 1.265 1.456 1.355
G4 0.886 0.887 0.887

Numerical Example 5
Surface data Unit mm

Surface number rd nd vd Effective diameter Surface ∞ ∞
1 * -5.6531 0.5000 1.58913 61.14 2.376
2 9.8000 0.2500 1.63494 23.22 2.159
3 * 16.8078 D3 2.137
4 * 2.9908 0.9110 1.85135 40.10 1.500
5 * -31.7144 0.1000 1.355
6 (Aperture) ∞ 0.1518 (Variable)
7 * 6.6515 0.7500 1.76802 49.24 1.268
8 -4.5000 0.4000 1.84666 23.78 1.185
9 * 4.8113 D9 1.058
10 44.8931 0.5000 1.81474 37.03 1.181
11 * 3.8464 D11 1.268
12 -32.1035 1.3000 1.82114 24.06 2.886
13 * -4.0000 0.4217 3.000
14 ∞ 0.3796 1.51633 64.14 2.961
15 ∞ 0.2900 2.957
Image plane ∞

Aspheric data 1st surface
K = -1.000, A4 = -3.19351e-03, A6 = 2.63420e-04, A8 = 1.16363e-05
Third side
K = -1.000, A4 = -2.77149e-03, A6 = 2.14794e-04, A8 = 5.18982e-05
4th page
K = -1.000, A4 = 1.88539e-03, A6 = 3.55638e-04
5th page
K = -1.000, A4 = 5.68662e-03, A6 = -7.24378e-04
7th page
K = 0.000, A4 = 1.78188e-02, A6 = -8.88828e-04
9th page
K = 11.588, A4 = 2.35797e-02, A6 = -1.00377e-04, A8 = 1.61425e-04
11th page
K = 0.000, A4 = -1.32598e-03, A6 = 2.94203e-04, A8 = -3.40185e-04
Side 13
K = -1.000, A4 = 5.47362e-03, A6 = -6.78501e-04, A8 = 2.75097e-05

Various data

Zoom ratio 2.821

Wide angle Medium telephoto

Focal length 4.570 7.640 12.890
FNO. 3.137 4.383 5.181
Angle of view 2ω 72.832 41.710 24.978
Image height 2.900 2.900 2.900
BF 0.962 0.962 0.962
Total lens length 12.871 12.871 12.871
Object distance ∞ ∞ ∞
D3 4.231 2.167 0.172
D9 0.758 0.721 1.542
D11 2.057 4.157 5.332
Diaphragm diameter 1.100 1.100 1.300
Entrance pupil position 3.165 2.343 1.167
Exit pupil position -17.126 44.144 18.147
Front principal point position 6.580 11.335 23.725
Rear principal point position -4.280 -7.350 -12.600

Lens Start surface Focal length
L11 1 -6.013
L12 2 36.513
L21 4 3.249
L22 7 3.600
L23 8 -2.693
L3 10 -5.192
L4 12 5.451

Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 -7.196 0.750 0.116 -0.345
G2 4 3.400 2.313 -0.522 -1.599
G3 10 -5.192 0.500 0.303 0.026
G4 12 5.451 2.101 0.799 -0.573

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.433 -0.588 -0.897
G3 1.742 2.147 2.373
G4 0.842 0.842 0.842

Numerical Example 6
Surface data Unit mm

Surface number rd nd vd Effective diameter Surface ∞ ∞
1 * -19.3192 0.4988 1.76802 49.24 2.583
2 * 3.7522 0.4683 1.63387 23.38 2.307
3 * 11.3663 D3 2.287
4 * 2.6413 0.8593 1.69350 53.21 1.473
5 * -9.2555 0.1569 1.381
6 (Aperture) ∞ 0.1202 (Variable)
7 * 6.3775 0.6959 1.76802 49.24 1.175
8 -17.7460 0.4046 1.84666 23.78 1.035
9 * 2.5760 D9 0.900
10 * -2150.7307 0.4011 1.58913 61.14 1.778
11 * 8.3413 D11 1.857
12 * -7.5498 0.9821 1.82114 24.06 2.555
13 * -4.0253 D13 2.724
14 ∞ 0.3796 1.51633 64.14 2.944
15 ∞ 0.4000 2.966
Image plane ∞

Aspheric data 1st surface
K = -55.536, A4 = -9.05980e-03, A6 = 1.14637e-03, A8 = -5.51750e-05
Second side
K = -5.943
Third side
K = 3.375, A4 = -8.51272e-03, A6 = 1.43185e-03, A8 = -6.70214e-05
4th page
K = -2.992, A4 = 1.71186e-02, A6 = -1.00737e-03, A8 = 4.64173e-04
5th page
K = -0.989, A4 = 8.39214e-03, A6 = -8.19252e-04, A8 = 2.03175e-04
7th page
K = 0.788, A4 = 5.33856e-03, A6 = -1.80989e-03, A8 = -4.20069e-04
9th page
K = 1.499, A4 = 6.20768e-03, A6 = -5.64490e-04, A8 = -1.23795e-04
10th page
K = 958794.047, A4 = 1.75804e-03, A6 = 1.99109e-03, A8 = -4.76253e-04
11th page
K = -0.095, A4 = 3.52958e-03, A6 = 1.43329e-03, A8 = -3.48716e-04
12th page
K = -0.216
Side 13
K = -0.637, A4 = 4.61435e-04, A6 = -1.26973e-04, A8 = -1.09864e-06

Various data

Zoom ratio 2.838

Wide angle Medium telephoto

Focal length 4.538 7.640 12.880
FNO. 3.339 4.651 5.209
Angle of view 2ω 72.624 42.356 24.646
Image height 2.900 2.900 2.900
BF 2.364 2.306 2.176
Total lens length 13.369 13.374 13.368
Object distance ∞ ∞ ∞
D3 4.526 2.251 0.195
D9 0.863 0.766 4.061
D11 1.028 3.465 2.347
D13 1.714 1.655 1.526
Diaphragm diameter 1.000 1.000 1.250
Entrance pupil position 3.512 2.608 1.385
Exit pupil position -5.255 -15.770 -27.703
Front principal point position 5.348 7.018 8.713
Rear principal point position -4.136 -7.241 -12.480

Lens Start surface Focal length
L11 1 -4.053
L12 2 8.631
L21 4 3.053
L22 7 6.186
L23 8 -2.633
L3 10 -14.103
L4 12 9.329

Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 -7.490 0.967 0.314 -0.247
G2 4 4.036 2.237 -1.225 -1.943
G3 10 -14.103 0.401 0.251 -0.001
G4 12 9.329 0.982 1.026 0.547

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.576 -0.854 -1.511
G3 1.306 1.472 1.379
G4 0.805 0.812 0.825
G5 1.000 1.000 1.000

Numerical Example 7
Surface data Unit mm

Surface number rd nd vd Effective diameter Surface ∞ ∞
1 * -20.6604 0.6681 1.69350 53.21 2.556
2 * 6.2554 D2 2.275
3 * 2.8735 1.2776 1.77377 47.17 1.550
4 -41.3684 0.5180 1.79491 25.63 1.357
5 * 10.6571 0.5000 1.208
6 (Aperture) ∞ 0.1965 (Variable)
7 * 7.5874 0.8263 1.76802 49.24 1.136
8 * -21.6754 D8 1.217
9 * 279.5342 0.3790 1.82114 24.06 1.225
10 * 3.4792 D10 1.229
11 * -7.1348 0.9360 1.79491 25.63 2.746
12 * -3.7927 1.3721 2.868
13 ∞ 0.4000 1.51633 64.14 2.972
14 ∞ 0.4000 2.983
Image plane ∞

Aspheric data 1st surface
K = -28.194, A4 = -9.53942e-03, A6 = 1.14164e-03, A8 = -5.01129e-05
Second side
K = -0.224, A4 = -9.75476e-03, A6 = 1.35826e-03, A8 = -4.78131e-05
Third side
K = 0.624, A4 = -1.58057e-03, A6 = -1.23052e-04, A8 = 7.62687e-06
5th page
K = 44.632, A4 = 5.76135e-04, A6 = 1.26800e-03, A8 = -7.09871e-05
7th page
K = -1.283, A4 = -2.54498e-02, A6 = -2.93083e-03, A8 = -1.21006e-03
8th page
K = 44.767, A4 = -2.16942e-02, A6 = -2.05558e-03, A8 = -1.25759e-05
9th page
K = -560206.977
10th page
K = -0.582, A4 = 7.46329e-03, A6 = 1.55863e-03, A8 = -8.04564e-04
11th page
K = -4.214
12th page
K = -0.006, A4 = 4.15000e-03, A6 = -2.49039e-05, A8 = -2.17406e-05, A10 = 2.21954e-06

Various data

Zoom ratio 2.816

Wide angle Medium telephoto

Focal length 4.574 7.639 12.879
FNO. 3.228 3.726 5.123
Angle of view 2ω 70.712 41.233 24.715
Image height 2.900 2.900 2.900
BF 2.036 2.036 2.036
Total lens length 13.864 13.864 13.864
Object distance ∞ ∞ ∞
D2 4.476 2.312 0.201
D8 0.611 0.650 1.363
D10 1.439 3.564 4.963
Diaphragm diameter 0.900 1.100 1.100
Entrance pupil position 3.777 3.155 2.278
Exit pupil position -5.287 -14.748 -40.735
Front principal point position 5.494 7.317 11.279
Rear principal point position -4.174 -7.239 -12.479

Lens Start surface Focal length
L1 1 -6.854
L21 3 3.517
L22 4 -10.614
L23 7 7.409
L3 9 -4.293
L4 11 9.062

Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 -6.854 0.668 0.300 -0.091
G2 3 3.459 3.318 0.621 -1.898
G3 9 -4.293 0.379 0.211 0.003
G4 11 9.062 2.708 0.990 -1.109

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.403 -0.539 -0.803
G3 1.987 2.482 2.808
G4 0.833 0.833 0.833

Numerical Example 8
Surface data Unit mm

Surface number rd nd vd Effective diameter Surface ∞ ∞
1 * -23.8081 0.4000 1.90270 31.00 1.764
2 * 2.2994 0.3419 1.467
3 * 2.8941 0.4964 2.10223 16.77 1.475
4 * 5.3026 D4 1.420
5 * 2.1625 0.8676 1.76802 49.24 1.201
6 * -6.2445 0.1994 1.091
7 (Aperture) ∞ 0.0000 (Variable)
8 * 6.5304 0.5563 1.49700 81.54 0.943
9 -11.0440 0.4000 2.10223 16.77 0.864
10 * 6.7381 D10 0.803
11 * -4.9986 0.4000 1.53071 55.67 0.915
12 * 6.1075 D12 1.016
13 * -4.3703 0.6790 2.10223 16.77 2.225
14 * -2.6586 0.3758 2.242
15 ∞ 0.3000 1.51633 64.14 2.270
16 ∞ 0.3500 2.276
Image plane ∞

Aspheric data 1st surface
K = -10.000, A4 = 4.48967e-03, A6 = -2.58325e-03, A8 = 2.70892e-04
Second side
K = 0.528, A4 = -1.10216e-02, A6 = 6.00177e-03, A8 = -3.60751e-03
Third side
K = -1.683, A4 = -1.62024e-02, A6 = 1.06888e-02, A8 = -2.57278e-03
4th page
K = -10.000, A4 = -1.24411e-02, A6 = 6.03283e-03, A8 = -1.54408e-03
5th page
K = -0.330, A4 = -6.66268e-03, A6 = -7.36472e-04, A8 = 2.13320e-03
6th page
K = 3.642, A4 = 2.02813e-02, A6 = 5.86325e-03, A8 = -1.69631e-03
8th page
K = -7.584, A4 = 6.35851e-02, A6 = 3.93734e-02, A8 = -1.23472e-02
10th page
K = -10.000, A4 = 5.93583e-02, A6 = 2.28767e-02, A8 = 3.08419e-02
11th page
K = -9.807, A4 = 2.12775e-02, A6 = -4.53840e-02, A8 = -2.43365e-03
12th page
K = -0.858, A4 = 5.63611e-02, A6 = -5.02019e-02, A8 = 8.82711e-03
Side 13
K = 1.905, A4 = 1.75077e-02, A6 = 1.42222e-03
14th page
K = 0.102, A4 = 2.50940e-02, A6 = -3.51630e-04, A8 = 3.23344e-04

Various data

Zoom ratio 2.800

Wide angle Medium telephoto

Focal length 2.912 4.629 8.154
FNO. 3.500 4.729 4.800
Angle of view 2ω 84.169 52.256 29.967
Image height 2.250 2.250 2.250
BF 0.924 0.924 0.924
Total lens length 9.998 9.998 9.998
Object distance ∞ ∞ ∞
D4 2.912 1.582 0.100
D10 0.297 0.260 1.135
D12 1.525 2.891 3.499
Diaphragm diameter 0.651 0.651 0.954
Entrance pupil position 2.300 1.927 1.315
Exit pupil position -7.694 -35.857 54.178
Front principal point position 4.231 5.973 10.717
Rear principal point position -2.532 -4.291 -7.820

Lens Start surface Focal length
L11 1 -2.306
L12 3 5.217
L21 5 2.190
L22 8 8.345
L23 9 -3.752
L3 11 -5.116
L4 13 5.098

Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 -4.287 1.238 0.105 -0.663
G2 5 2.446 2.023 -0.336 -1.340
G3 11 -5.116 0.400 0.116 -0.142
G4 13 5.098 0.679 0.683 0.415

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.482 -0.652 -1.079
G3 1.577 1.834 1.952
G4 0.894 0.903 0.903

Numerical Example 9
Surface data Unit mm

Surface number rd nd vd Effective diameter Surface ∞ ∞
1 * 10.1679 0.4000 1.77377 47.17 1.804
2 * 1.8406 0.3689 1.449
3 * 2.4091 0.5290 1.70000 15.00 1.449
4 * 3.3582 D4 1.400
5 * 2.0501 0.7343 1.76802 49.24 1.149
6 * -27.4479 0.1994 1.049
7 (Aperture) ∞ 0.0000 (Variable)
8 * 4.4431 0.5434 1.49700 81.54 0.931
9 -4.9922 0.4000 1.70000 15.00 0.888
10 * 27.3397 D10 0.846
11 * -2.0238 0.4000 1.53071 55.67 0.868
12 * -24.7934 D12 0.946
13 * -4.1717 0.8192 1.70000 15.00 2.139
14 * -2.5605 0.5342 2.223
15 ∞ 0.3000 1.51633 64.14 2.258
16 ∞ 0.3500 2.263
Image plane ∞

Aspheric data 1st surface
K = -2.968, A4 = 1.54293e-02, A6 = -8.65844e-03, A8 = 8.28284e-04
Second side
K = 0.002, A4 = 8.96390e-03, A6 = -1.08004e-03, A8 = -5.17338e-03
Third side
K = -0.982, A4 = -4.16429e-02, A6 = 1.42120e-03
4th page
K = -4.286, A4 = -4.16742e-02, A6 = -2.66315e-03, A8 = 1.91253e-03
5th page
K = -0.227, A4 = 1.02517e-03, A6 = 8.62020e-04, A8 = 2.01632e-03
6th page
K = -9.886, A4 = -7.92533e-03, A6 = 1.68283e-02, A8 = -4.56115e-03
8th page
K = -3.826, A4 = -2.05536e-02, A6 = 3.91404e-02, A8 = -1.54510e-02
10th page
K = -9.474, A4 = 4.13517e-02, A6 = 1.51235e-02, A8 = 2.94491e-02
11th page
K = -9.859, A4 = 6.25595e-02, A6 = -1.76258e-02, A8 = -5.16373e-02
12th page
K = -10.000, A4 = 2.13359e-01, A6 = -9.44745e-02, A8 = 9.69920e-04
Side 13
K = 2.062, A4 = 1.88493e-02, A6 = 1.42105e-03
14th page
K = 0.080, A4 = 2.24501e-02, A6 = -5.53882e-04, A8 = 3.18452e-04

Various data

Zoom ratio 2.795

Wide angle Medium telephoto

Focal length 2.917 4.633 8.154
FNO. 3.500 4.662 4.800
Angle of view 2ω 84.108 52.711 30.750
Image height 2.250 2.250 2.250
BF1.082 1.082 1.082
Total lens length 9.998 9.998 9.998
Object distance ∞ ∞ ∞
D4 2.873 1.548 0.100
D10 0.240 0.227 0.840
D12 1.408 2.746 3.581
Diaphragm diameter 0.665 0.665 0.937
Entrance pupil position 2.457 2.069 1.428
Exit pupil position -5.371 -11.293 -24.106
Front principal point position 4.062 4.966 6.940
Rear principal point position -2.533 -4.299 -7.825

Lens Start surface Focal length
L11 1 -2.967
L12 3 9.905
L21 5 2.511
L22 8 4.822
L23 9 -6.000
L3 11 -4.178
L4 13 7.831

Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 -4.046 1.298 0.414 -0.453
G2 5 2.234 1.877 0.026 -1.159
G3 11 -4.178 0.400 -0.023 -0.286
G4 13 7.831 0.819 1.032 0.633

Group magnification
Wide angle Medium telephoto
G1 0.000 0.000 0.000
G2 -0.433 -0.582 -0.935
G3 1.776 2.083 2.281
G4 0.938 0.945 0.945

  Next, the values taken by the above-described Example 1 (Numerical Example 1) to Example 9 (Numerical Example 9) in the above-described conditional expressions (1) to (8) are shown.

Example values for each conditional expression
Conditional expression (1) Conditional expression (2) Conditional expression (5) Conditional expression (6) Conditional expression (3) (8) Conditional expression (4) (7)
Example 1 0.50 0.90 1.10 1.98 -0.40 0.027
Example 2 0.50 0.92 1.10 2.01 -0.35 0.027
Example 3 0.53 0.96 1.40 2.53 -0.01 0.023
Example 4 0.50 0.91 1.32 2.41 -0.06 0.023
Example 5 0.44 0.94 1.17 2.48 -0.23 0.022
Example 6 0.53 0.98 1.39 2.58 0.01 0.023
Example 7 0.45 0.89 1.19 2.36 -1.30 0.019
Example 8 0.50 0.88 1.09 1.91 -0.51 0.047
Example 9 0.46 0.83 0.99 1.80 -0.86 0.054

  The variable power optical system according to the present invention as described above is used for a photographing apparatus, for example, a digital camera or a video camera, which performs photographing by forming an object image formed by the variable power optical system on an image pickup device such as a CCD. Can do. Specific examples are shown below.

  FIGS. 31, 32 and 33 are conceptual diagrams showing the configuration of a digital camera using the present invention. FIG. 31 is a front perspective view showing the appearance of the digital camera, and FIG. 32 is a rear perspective view of the digital camera. FIG. 33 is a perspective view schematically showing the configuration of the digital camera.

  The digital camera is provided with a photographing opening 1, a finder opening 2, and a flash light emitting unit 3 on the front surface. A shutter button 4 is provided at the top. A liquid crystal display monitor 5 and an information input unit 6 are provided on the back side. The digital camera includes a variable power optical system 7, processing means 8, recording means 9, and viewfinder optical system 10. Also, a cover member 12 is disposed in the finder opening 2 and the opening 11 provided on the back side of the digital camera on the exit side of the finder optical system 10. A cover member 13 is also disposed in the photographing opening 1.

  When the shutter button 4 arranged on the upper part of the digital camera is pressed, photographing is performed through the variable magnification optical system 7, for example, the variable magnification optical system as described in the first embodiment of the present invention in conjunction therewith. The object image is formed on the imaging surface of the CCD 7a, which is a solid-state imaging device, via the variable magnification optical system 7 and the cover glass CG. Image information of the object image formed on the imaging surface of the CCD 7a is recorded in the recording means 9 via the processing means 8. The recorded image information can be taken out by the processing means 8 and displayed as an electronic image on the liquid crystal display monitor 5 provided on the back of the camera.

The finder optical system 10 includes a finder objective optical system 10a, an erecting prism 10b, and an eyepiece optical system 10c. Light from the subject incident from the finder opening 2, the objective optical diameter 10a finder, led to the erecting prism 10b which is an image erecting member, forming a erect image an object image in a field frame 10b ₁ Then, the object image is guided to the observer's eye E by the eyepiece optical system 10c.

  In the digital camera configured in this way, since the variable magnification optical system 7 has a high magnification ratio and is small, it is possible to ensure good performance and to realize a reduction in the size of the digital camera.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group L1, L11, L12, L21, L22, L23, L3, L4 Lens element Lc Optical axis S Aperture stop CG Cover glass IM Imaging surface E Observer's eyeball 1 Shooting aperture 2 Viewfinder aperture 3 Flash light emitting unit 4 Shutter button 5 LCD monitor 6 Information input unit 7 Variable magnification optical system 7a CCD
8 Processing means 9 Recording means 10 Viewfinder optical system 10a Objective optical system for viewfinder 10b Erecting prism 10b ₁ Field frame 10c Eyepiece optical system 11 Aperture 12, 13 Cover member

Claims (7)

A zoom optical system having a zoom ratio of 2.5 or more,
In order from the object side, at least a first lens group having a negative refractive power and a second lens group having a positive refractive power are included.
A variable magnification optical system characterized by satisfying the following conditional expressions (1) and (2):
0.44 ≦ | fv | / (fw · ft) ^1/2 ≦ 0.61 (1)
0.5 ≦ | f1 | / (fw · ft) ^1/2 ≦ 1.05 (2)
However,
fv is a focal length of a lens group having a main zooming effect,
f1 is the focal length of the first lens group,
fw is the focal length of the variable magnification optical system at the wide-angle end,
ft is the focal length of the variable magnification optical system at the telephoto end,
It is.   The first lens group, the second lens group, a third lens group having a negative refractive power, and a fourth lens group having a positive refractive power in order from the object side. The zoom optical system according to claim 1. The second lens group has a meniscus shape having a convex shape on the object side in the entire group,
The zoom lens system according to claim 1 or 2, wherein the following conditional expression (3) is satisfied.
−0.6 ≦ (Ra2−Rb2) / (Ra2 + Rb2) ≦ 0.2 (3)
However,
Ra2 is the radius of curvature of the surface closest to the object side of the second lens group,
Rb2 is the radius of curvature of the surface closest to the image plane of the second lens group,
It is. The lens group having the main zooming action includes at least one lens having a negative refractive power and a lens having a positive refractive power,
The zoom lens system according to any one of claims 1 to 3, wherein the following conditional expression (4) is satisfied.
0.015 ≦ | 1 / Vmin−1 / Vmax | ≦ 0.03 (4)
However,
Vmax is the largest Abbe number among the Abbe numbers of the lenses included in the lens group having the main zooming effect,
Vmin is the smallest Abbe number among the Abbe numbers of the lenses included in the lens group having the main zooming action,
The Abbe number is represented by (nd-1) / (nF-nC),
nd, nC, and nF are the refractive indexes of the d-line, C-line, and F-line,
It is. A variable magnification optical system having a variable magnification ratio of 2.5 or more, and an electronic image sensor disposed on the most image side of the variable magnification optical system,
The zoom optical system includes at least a first lens group having a negative refractive power and a second lens group having a positive refractive power in order from the object side,
The lens group having a main zooming action has at least one convex lens and at least one concave lens,
An imaging apparatus that satisfies the following conditional expression (4), conditional expression (5), and conditional expression (6):
0.015 ≦ | 1 / Vmin−1 / Vmax | ≦ 0.03 (4)
0.2 ≦ | fv | /IH≦1.5 (5)
1.0 ≦ | f1 | /IH≦2.7 (6)
However,
fv is a focal length of the lens group having the main zooming effect,
f1 is the focal length of the first lens group,
IH is the image height of the image sensor,
Vmax is the largest Abbe number among the Abbe numbers of the lenses included in the lens group having the main zooming effect,
Vmin is the smallest Abbe number among the Abbe numbers of the lenses included in the lens group having the main zooming action,
The Abbe number is represented by (nd-1) / (nF-nC),
nd, nC, and nF are the refractive indexes of the d-line, C-line, and F-line,
It is.   The variable magnification optical system includes, in order from the object side, the first lens group, the second lens group, a third lens group having a negative refractive power, and a fourth lens group having a positive refractive power. The imaging apparatus according to claim 5, wherein the imaging apparatus is configured. The second lens group has a meniscus shape having a convex shape on the object side in the entire group,
The imaging apparatus according to claim 5 or 6, wherein the following conditional expression (3) is satisfied.
−0.6 ≦ (Ra2−Rb2) / (Ra2 + Rb2) ≦ 0.2 (3)
However,
Ra2 is the radius of curvature of the surface closest to the object side of the second lens group,
Rb2 is the radius of curvature of the surface closest to the image plane of the second lens group,
It is.

Images