JP2011059598A - Variable power optical system and imaging apparatus including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable power optical system whose entire length is small as compared with image height and whose aberration is good. <P>SOLUTION: The variable power optical system includes, in order from an object side: a first lens group having negative refractive power; a second lens group having positive refractive power; a third lens group having negative refractive power; and a fourth lens group having positive refractive power. The second lens group includes at least: a positive lens; and a negative lens. The fourth lens group includes a positive lens. The variable power optical system satisfies 10&le;Vd4g&le;45, 2.2&le;¾&alpha;/f1¾+(&alpha;/f2)-0.026&times;Vd4g&le;5.0 and 10&le;Vdmax-Vdmin&le;80, wherein &alpha;=(FLw&times;FLt)<SP>1/2</SP>, FLw is a focal length at a wide angle end, FLt is a focal length at a telephoto end, f1 is a focal length of the first lens group, f2 is a focal length of the second lens group, Vd4g is an Abbe number of the positive lens in the fourth lens group for a d-line, Vdmax is an Abbe number of glass material having the lowest dispersion in the glass material of the second lens group, for the d-line, and Vdmin is an Abbe number of glass material having the highest dispersion in the glass material of the second lens group, for the d-line. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a variable magnification optical system in which aberration is favorably corrected while reducing the value of the total length as compared with 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 power optical system aiming at satisfying such a requirement, for example, there is a variable power optical system disclosed in Patent Document 1. Patent Document 1 relates to a variable magnification optical system for the purpose of correcting lateral chromatic aberration. If an attempt is made to achieve an ultra-compact variable magnification optical system, the refractive power of the second lens group becomes strong, and chromatic aberration of magnification at the telephoto end becomes a problem. In Patent Document 1, this problem is corrected by appropriately selecting the Abbe number of the fourth lens group.

International Publication WO2006 / 115107

  However, in the optical system disclosed in Patent Document 1, it is said that both the reduction of the value of the total length compared to the image height (shortening) and the correction of the aberrations are achieved. hard.

  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 value of the total length compared to the image height, and An object of the present invention is to provide an imaging apparatus having the same. The total length compared to the image height means (full length) / (image height).

In order to solve the above problems, the zoom optical system of the present invention has, 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 refractive power. A third lens group and a fourth lens group having a positive refractive power; the second lens group includes at least one positive lens and a negative lens; the fourth lens group includes a positive lens; The following conditional expressions (1), (2), and (3) are satisfied.
Conditional expression (1) 10 ≦ Vd4g ≦ 45
Conditional expression (2) 2.2 ≦ | α / f1 | + (α / f2) −0.026 × Vd4g ≦ 5.0
Conditional expression (3) 10 ≦ Vdmax−Vdmin ≦ 80
However,
α = (FLw × FLt) ^1/2
FLw is the focal length of the entire variable magnification optical system at the wide-angle end,
FLt is the focal length of the entire variable magnification optical system at the telephoto end,
f1 is the focal length of the first lens group,
f2 is the focal length of the second lens group,
Vd4g is the Abbe number with respect to the d-line of the positive lens in the fourth lens group,
Vdmax is the Abbe number for the d-line of the glass material having the lowest dispersion among the glass materials of the lenses of the second lens group,
Vdmin is the Abbe number for the d-line of the glass material having the highest dispersion among the glass materials of the lenses of the second lens group,
It is.

Moreover, it is preferable that the variable magnification optical system of the present invention satisfies the following conditional expression (4).
Conditional expression (4) 0.45 ≦ | f1 | / (FLw × FLt) ^1/2 ≦ 1.60
However,
f1 is the focal length of the first lens group,
FLw is the focal length of the entire variable magnification optical system at the wide-angle end,
FLt is the focal length of the entire variable magnification optical system at the telephoto end,
It is.

Moreover, it is preferable that the variable magnification optical system of the present invention satisfies the following conditional expression (5).
Conditional expression (5) 0.30 ≦ f2 / (FLw × FLt) ^1/2 ≦ 1.10.
However,
f2 is the focal length of the second lens group,
FLw is the focal length of the entire variable magnification optical system at the wide-angle end,
FLt is the focal length of the entire variable magnification optical system at the telephoto end,
It is.

In the zoom optical system according to the present invention, the second lens group includes, in order from the object side, a first lens element, a second lens element, and a third lens element having positive refractive power, and the first lens element. It is preferable that the lens element has a convex shape on the object side and satisfies the following conditional expression (6).
Conditional expression (6) -1.0 <(R2a-R2b) / (R2a + R2b) <1.0
However,
R2a is the radius of curvature of the object side surface of the second lens element,
R2b is the radius of curvature of the image side surface of the third lens element,
It is.

In the variable magnification optical system of the present invention, it is preferable that the positive lens of the fourth lens group has a concave shape on the object side and satisfies the following conditional expression (7).
Conditional Expression (7) 0 <(R4a−R4b) / (R4a + R4b) <1.0
However,
R4a is the radius of curvature of the object side surface of the positive lens of the fourth lens group,
R4b is the radius of curvature of the image side surface of the positive lens in the fourth lens group,
It is.

  The imaging apparatus of the present invention is characterized by having the variable magnification optical system and the imaging element of the present invention.

The image pickup apparatus of the present invention further includes a variable magnification optical system that forms an optical image of an object and an image pickup device, and the image pickup device electrically converts an optical image formed by the variable power optical system. The variable magnification optical system converts, 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. A lens group and a fourth lens group having a positive refractive power, the second lens group includes at least one positive lens and a negative lens, the fourth lens group includes a positive lens, and the following conditions: It is preferable that the expressions (1), (8) and (3) are satisfied.
Conditional expression (1) 10 ≦ Vd4g ≦ 45
Conditional Expression (8) −0.27 ≦ | IH / f1 | + (IH / f2) −0.05 × Vd4g ≦ 3.0
Conditional expression (3) 10 ≦ Vdmax−Vdmin ≦ 80
However,
IH is the image height of the image sensor,
f1 is the focal length of the first lens group,
f2 is the focal length of the second lens group,
Vd4g is the Abbe number with respect to the d-line of the positive lens in the fourth lens group,
Vdmax is the Abbe number for the d-line of the glass material having the lowest dispersion among the glass materials of the lenses of the second lens group,
Vdmin is the Abbe number for the d-line of the glass material having the highest dispersion among the glass materials of the lenses of the second lens group,
It is.

Moreover, it is preferable that the imaging device of this invention satisfies the following conditional expressions (9).
Conditional expression (9) 1.0 ≦ | f1 | /IH≦2.8
However,
f1 is the focal length of the first lens group,
IH is the image height of the image sensor,
It is.

Moreover, it is preferable that the imaging device of the present invention satisfies the following conditional expression (10).
Conditional expression (10) 0.2 ≦ | f2 | /IH≦1.8
However,
f2 is the focal length of the second lens group,
IH is the image height of the image sensor,
It is.

In the imaging apparatus of the present invention, the second lens group includes a first lens element, a second lens element, and a third lens element having a positive refractive power in order from the object side, and the first lens element is an object. It is preferable to have a convex shape on the side and satisfy the following conditional expression (6).
Conditional expression (6) -1.0 <(R2a-R2b) / (R2a + R2b) <1.0
However,
R2a is the radius of curvature of the object side surface of the second lens element,
R2b is the radius of curvature of the image side surface of the third lens element,
It is.

In the image pickup apparatus of the present invention, it is preferable that the positive lens of the fourth lens group of the variable magnification optical system has a concave shape on the object side and satisfies the following conditional expression (7).
Conditional Expression (7) 0 <(R4a−R4b) / (R4a + R4b) <1.0
However,
R4a is the radius of curvature of the object side surface of the positive lens of the fourth lens group,
R4b is the radius of curvature of the image side surface of the positive lens in the fourth lens group,
It is.

  According to the variable magnification optical system of the present invention, it is possible to provide a variable magnification optical system in which aberration is satisfactorily corrected while reducing the value of the total length compared to the image height, and an imaging apparatus having the variable magnification optical system. .

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. 7A is an aberration diagram for Example 4 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. 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. FIG. 10A is an aberration diagram for Example 5 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. 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 lens sectional view of Example 10 of the variable magnification optical system concerning the present invention. FIG. 11A is an aberration diagram for focusing at infinity according to example 10, where (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 70% image high coma aberration diagram of Example 10, where (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 11 of the variable magnification optical system concerning the present invention. FIG. 11A is an aberration diagram for focusing at infinity according to example 11, where (a) shows the state at the wide-angle end, (b) shows the middle, and (c) shows the state at the telephoto end. FIG. 14 is a 70% image high coma aberration diagram of Example 11, 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 front perspective view which shows the external appearance of the digital camera incorporating the variable magnification optical system of this invention. It is a back perspective view which shows the external appearance of the digital camera shown in FIG. FIG. 40 is a perspective view schematically showing the configuration of the digital camera shown in FIG. 39.

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 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, a third lens group having a negative refractive power, and a positive lens The second lens group includes at least one positive lens and a negative lens, the fourth lens group includes a positive lens, and the following conditional expressions (1) and (2) ), (3) is satisfied.
Conditional expression (1) 10 ≦ Vd4g ≦ 45
Conditional expression (2) 2.2 ≦ | α / f1 | + (α / f2) −0.026 × Vd4g ≦ 5.0
Conditional expression (3) 10 ≦ Vdmax−Vdmin ≦ 80
However,
α = (FLw × FLt) ^1/2
FLw is the focal length of the entire variable magnification optical system at the wide-angle end,
FLt is the focal length of the entire variable magnification optical system at the telephoto end,
f1 is the focal length of the first lens group,
f2 is the focal length of the second lens group,
Vd4g is the Abbe number for the d-line of the positive lens in the fourth lens group,
Vdmax is the Abbe number for the d-line of the glass material having the lowest dispersion among the glass materials of the lenses of the second lens group,
Vdmin is the Abbe number for the d-line of the glass material having the highest dispersion among the glass materials of the lenses of the second lens group,
It is.

  In order to achieve an optical system in which the total length is small compared to the image height and various aberrations are well corrected, each lens group must have its power increased and various aberrations corrected. Was necessary. For example, when the fourth lens group is composed of one positive lens, the positive lens is preferably composed of a low dispersion material in order to suppress the occurrence of chromatic aberration with a single lens. However, if the value of the total length relative to the image height is further reduced, the power required for the first lens group and the second lens group increases, and the power and various aberrations (monochromatic / chromatic aberration) in each group. ) The balance of correction cannot be maintained.

  Specifically, the power required in the first lens group increases, and the variation of monochromatic aberration (spherical aberration / coma aberration) during zooming increases. Therefore, in order to correct this, fluctuations in monochromatic aberration (spherical aberration / coma aberration) are mainly suppressed in the first lens group. However, along with this, the occurrence of chromatic aberration increases in the first lens group. In addition, the power required in the second lens group increases and chromatic aberration is greatly generated.

  Therefore, in the variable magnification optical system of the present embodiment, the fourth lens group satisfies the conditional expression (1) in order to correct these aberrations satisfactorily. Conditional expression (1) indicates the Abbe number of the positive lens in the fourth lens group. Conditional expression (2) shows the relationship between the Abbe number of the positive lens of the fourth lens group and the power of the first lens group and the second lens group. Conditional expression (3) indicates the difference between the lowest dispersion glass material and the highest dispersion glass material of the second lens group.

  By satisfying both conditional expressions (1) and (2), it is possible to achieve a variable magnification optical system in which the total length is small compared to the image height and various aberrations are corrected satisfactorily. In addition, by satisfying conditional expression (3), it is possible to achieve a variable magnification optical system in which various aberrations are corrected satisfactorily.

  If the lower limit of conditional expression (1) is not reached, a desired optical system cannot be achieved because there is no actual glass material. On the other hand, if the upper limit of conditional expression (1) is exceeded, it will be difficult to satisfactorily correct chromatic aberration of magnification at the telephoto end.

  If the lower limit of conditional expression (2) is not reached, the powers of the first lens group and the second lens group are insufficient, and the overall length cannot be shortened. On the other hand, if the upper limit value of conditional expression (2) is exceeded, the powers of the first lens group and the second lens group become too strong, and it becomes impossible to suppress fluctuations in spherical aberration and coma aberration during zooming.

  If the lower limit of conditional expression (3) is not reached, the chromatic aberration of the second lens group will be insufficiently corrected. If the upper limit value of conditional expression (3) is exceeded, mainly the chromatic aberration of the second lens group will be overcorrected.

  Thus, by satisfying the conditional expressions (1), (2), and (3) at the same time, a variable magnification optical system in which the total length value is small compared to the image height and various aberrations are well corrected is achieved. it can. Specifically, it is possible to achieve a variable magnification optical system in which spherical aberration, coma variation, and chromatic aberration are corrected particularly well.

Moreover, it is preferable that the following conditional expressions (1-1), (2-1), and (3-1) are satisfied instead of the conditional expressions (1), (2), and (3).
Conditional expression (1-1) 15 ≦ Vd4g ≦ 40
Conditional expression (2-1) 2.25 ≦ | α / f1 | + (α / f2) −0.026 × Vd4g ≦ 4.5
Conditional expression (3-1) 15 ≦ Vdmax−Vdmin ≦ 70

  When the conditional expressions (1-1), (2-1), and (3-1) are satisfied, a variable magnification optical system in which the total length is small compared to the image height and various aberrations are corrected more favorably. Can be achieved. Specifically, it is possible to achieve a variable power optical system in which spherical aberration, coma variation, and chromatic aberration are corrected more appropriately.

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

  Since the full length is fixed at the time of zooming, the strength of the lens frame can be easily secured. In addition, since the configuration of the lens frame can be simplified, the optical system can be reduced in size.

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

  Since the fourth lens group is fixed, the movable part can be made the minimum two lens groups. Thereby, since the lens frame structure can be simplified, the optical system can be downsized. Furthermore, aberration variation can be suppressed by arranging fixed groups on the object side and the image plane side of the two movable groups.

The variable magnification optical system of the present embodiment preferably satisfies the following conditional expression (4).
Conditional expression (4) 0.45 ≦ | f1 | / (FLw × FLt) ^1/2 ≦ 1.60
However,
f1 is the focal length of the first lens group,
FLw is the focal length of the entire variable magnification optical system at the wide-angle end,
FLt is the focal length of the entire variable magnification optical system at the telephoto end,
It is.

  Since the refractive power of the first lens group is strong, the virtual image point generated by the first lens group can be brought closer to the image plane side. As a result, the overall length of the optical system can be shortened. However, when the refractive power increases, it is generally difficult to correct aberrations. When the conditional expression (4) is satisfied, a variable magnification optical system in which the total length value is small compared to the image height and various aberrations are favorably corrected can be achieved. Specifically, it is possible to achieve a variable power optical system in which fluctuations in spherical aberration and coma particularly during zooming are corrected (suppressed).

  If the lower limit of conditional expression (4) is not reached, fluctuations in spherical aberration and coma during zooming cannot be suppressed. If the upper limit of conditional expression (4) is exceeded, it is difficult to bring the position of the virtual image generated by the first lens group closer to the image plane side, which is not desirable.

Moreover, it is preferable to satisfy the following conditional expression (4-1) instead of conditional expression (4).
Conditional expression (4-1) 0.50 ≦ | f1 | / (FLw × FLt) ^1/2 ≦ 1.04

  When the conditional expression (4-1) is satisfied, a variable magnification optical system in which the value of the total length compared to the image height is small and various aberrations are corrected better can be achieved. Specifically, it is possible to achieve a variable magnification optical system in which the variation of spherical aberration and coma aberration during the variable magnification is corrected (suppressed) better.

  In the variable magnification optical system of the present embodiment, it is preferable that the first lens group includes two or less lens elements.

In addition, the zoom optical system according to the present embodiment preferably satisfies the following conditional expression (5).
Conditional expression (5) 0.30 ≦ f2 / (FLw × FLt) ^1/2 ≦ 1.10.
However,
f2 is the focal length of the second lens group,
FLw is the focal length of the entire variable magnification optical system at the wide-angle end,
FLt is the focal length of the entire variable magnification optical system at the telephoto end,
It is.

  In general, since the refractive power of the second lens group is sufficiently strong, it is possible to reduce the amount of movement during zooming. As a result, the overall length of the optical system can be shortened. However, when the refractive power increases, it is generally difficult to correct aberrations. When the conditional expression (5) is satisfied, a variable magnification optical system in which the total length value is small compared to the image height and various aberrations are favorably corrected can be achieved. Specifically, it is possible to achieve a variable magnification optical system in which spherical aberration is corrected particularly well.

  If the lower limit of conditional expression (5) is not reached, the spherical aberration is deteriorated, which is not desirable. Exceeding the upper limit value of conditional expression (5) is undesirable because it increases the amount of movement during zooming.

Moreover, it is preferable to satisfy the following conditional expression (5-1) instead of conditional expression (5).
Conditional expression (5-1) 0.35 ≦ f2 / (FLw × FLt) ^1/2 ≦ 0.62

  When the conditional expression (5-1) is satisfied, a variable magnification optical system in which the value of the total length compared to the image height is small and various aberrations are corrected better can be achieved. Specifically, it is possible to achieve a variable magnification optical system in which spherical aberration is corrected more satisfactorily.

In the zoom optical system of the present embodiment, it is preferable that the second lens group has a first lens element (L21), a second lens element (L22), and a third lens element that have positive refractive power in order from the object side. (L23), the first lens element (L21) has a convex shape on the object side, and satisfies the following conditional expression (6).
Conditional expression (6) -1.0 <(R2a-R2b) / (R2a + R2b) <1.0
However,
R2a is the radius of curvature of the object side surface of the second lens element (L22),
R2b is the radius of curvature of the image side surface of the third lens element (L23),
It is.

  Conditional expression (6) indicates a shaping factor related to the second lens element (L22) and the third lens element (L23). In general, in a retrofocus type optical system, the main point position of the positive zoom group, which is the main zooming group, is brought closer to the object side, so that the total length can be shortened without physically buffering with the negative group. It becomes. When the conditional expression (6) is satisfied, a meniscus shape having a convex shape on the object side is obtained, so that the principal point of the second lens group can be brought closer to the object side. As a result, a variable magnification optical system in which various aberrations are favorably corrected can be achieved. Specifically, it is possible to achieve a variable power optical system in which fluctuations in spherical aberration and coma particularly during zooming are corrected well.

  If the lower limit of conditional expression (6) is not reached, fluctuations in spherical aberration and coma during zooming cannot be suppressed. If the upper limit of conditional expression (6) is exceeded, the principal point position of the second lens group cannot be brought closer to the object side. In addition, it becomes impossible to suppress fluctuations in spherical aberration and coma during zooming.

Moreover, it is preferable to satisfy the following conditional expression (6-1) instead of conditional expression (6).
Conditional expression (6-1) -0.8 <(R2a-R2b) / (R2a + R2b) <0.72

  When the conditional expression (6-1) is satisfied, a variable magnification optical system in which the value of the total length compared to the image height is small and various aberrations are corrected better can be achieved. Specifically, it is possible to achieve a variable magnification optical system in which the variation of spherical aberration and coma aberration at the time of variable magnification is corrected more satisfactorily.

  In the variable power optical system of the present embodiment, preferably, the second lens element (L22) and the third lens element (L23) have a positive refractive power and a negative refractive power, respectively.

  In the zoom optical system according to the present embodiment, it is preferable that the fourth lens group includes one lens element having positive refractive power.

In the zoom optical system of the present embodiment, it is preferable that the positive lens in the fourth lens group has a concave shape on the object side, and satisfies the following conditional expression (7).
Conditional Expression (7) 0 <(R4a−R4b) / (R4a + R4b) <1.0
However,
R4a is the radius of curvature of the object side surface of the positive lens in the fourth lens group,
R4b is the radius of curvature of the image side surface of the positive lens in the fourth lens group,
It is.

  Conditional expression (7) represents the shaping factor of the positive lens in the fourth lens group. When the conditional expression (7) is satisfied, the shape of the positive lens becomes a meniscus shape having a concave shape on the object side. As a result, a variable magnification optical system in which various aberrations are favorably corrected can be achieved. Specifically, it is possible to achieve a variable power optical system in which fluctuations in field curvature particularly during zooming are well corrected (suppressed). If the conditional expression (7) is not satisfied, it becomes impossible to suppress the fluctuation of the field curvature at the time of zooming.

Moreover, it is preferable to satisfy the following conditional expression (7-1) instead of conditional expression (7).
Conditional expression (7-1) 0.1 ≦ (R4a−R4b) / (R4a + R4b) <0.9

  If the conditional expression (7-1) is satisfied, a variable magnification optical system in which the value of the total length compared to the image height is small and various aberrations are corrected better can be achieved. Specifically, it is possible to achieve a variable power optical system in which fluctuations in curvature of field at the time of zooming are corrected (suppressed) more favorably.

  In addition, the imaging apparatus of the present embodiment is characterized by having the above-described variable magnification optical system and an imaging element.

In addition, the imaging apparatus according to the present embodiment preferably includes a variable magnification optical system that forms an optical image of an object and an image sensor, and the image sensor captures an optical image formed by the variable magnification optical system. The variable power optical system converts the image signal into an electrical image signal in order from the object side, the first lens group having negative refractive power, the second lens group having positive refractive power, and the third lens having negative refractive power. A lens group, and a fourth lens group having a positive refractive power; the second lens group includes at least one positive lens and a negative lens; the fourth lens group includes a positive lens; Satisfy (1), (8), (3).
Conditional expression (1) 10 ≦ Vd4g ≦ 45
Conditional Expression (8) −0.27 ≦ | IH / f1 | + (IH / f2) −0.05 × Vd4g ≦ 3.0
Conditional expression (3) 10 ≦ Vdmax−Vdmin ≦ 80
However,
IH is the image height of the image sensor,
f1 is the focal length of the first lens group,
f2 is the focal length of the second lens group,
Vd4g is the Abbe number for the d-line of the positive lens in the fourth lens group,
Vdmax is the Abbe number for the d-line of the glass material having the lowest dispersion among the glass materials of the lenses of the second lens group,
Vdmin is the Abbe number for the d-line of the glass material having the highest dispersion among the glass materials of the lenses of the second lens group,
It is.

  By satisfying both conditional expressions (1) and (8), it is possible to achieve a variable magnification optical system in which the total length is small compared to the image height and various aberrations are well corrected. In addition, by satisfying conditional expression (3), it is possible to achieve a variable magnification optical system in which various aberrations are corrected satisfactorily. Here, IH is the image height of the image sensor, but more specifically, IH is half of the diagonal length on the imaging surface 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 (1) and conditional expression (3) are as already described. The technical significance and operational effects of conditional expression (8) are the same as those of conditional expression (2).

  Thus, by satisfying the conditional expressions (1), (8), and (3) at the same time, it is possible to achieve a variable magnification optical system in which the total length is small compared to the image height and various aberrations are well corrected. . Specifically, it is possible to achieve a variable magnification optical system in which spherical aberration, coma variation, and chromatic aberration are corrected particularly well.

Further, it is preferable that the following conditional expressions (1-1), (8-1), and (3-1) are satisfied instead of the conditional expressions (1), (8), and (3).
Conditional expression (1-1) 15 ≦ Vd4g ≦ 40
Conditional expression (8-1) −0.25 ≦ | α / F1 | + (α / F2) −0.026 × Vd4g ≦ 2.5
Conditional expression (3-1) 15 ≦ Vdmax−Vdmin ≦ 70

  When the conditional expressions (1-1), (8-1), and (3-1) are satisfied, the variable magnification optical system in which the total length is small compared to the image height and various aberrations are corrected more favorably. Can be achieved. Specifically, it is possible to achieve a variable magnification optical system in which spherical aberration, coma variation, and chromatic aberration are corrected more appropriately, especially during variable magnification.

  The imaging apparatus of the present embodiment preferably has a variable power optical system in which the first lens group is fixed at the time of zooming from the wide-angle end to the telephoto end or when shooting from infinite shooting to close-up shooting. . The imaging apparatus of the present embodiment preferably has a variable power optical system in which the fourth lens group is fixed at the time of zooming from the wide-angle end to the telephoto end or when shooting from infinite shooting to close-up shooting. . The points for fixing the first lens group and the fourth lens group are as described above.

The imaging apparatus according to the present embodiment preferably satisfies the following conditional expression (9).
Conditional expression (9) 1.0 ≦ | f1 | /IH≦2.8
However,
f1 is the focal length of the first lens group,
IH is the image height of the image sensor,
It is.

  The technical significance and operational effects of conditional expression (9) are the same as in conditional expression (4). Note that IH is as described above.

Moreover, it is preferable to satisfy the following conditional expression (9-1) instead of conditional expression (9).
Conditional expression (9-1) 1.8 ≦ | f1 | /IH≦2.6

  In the imaging apparatus of this embodiment, it is preferable that the first lens group of the variable magnification optical system includes two or less lens elements.

The imaging apparatus according to the present embodiment preferably satisfies the following conditional expression (10).
Conditional expression (10) 0.2 ≦ | f2 | /IH≦1.8
However,
f2 is the focal length of the second lens group,
IH is the image height of the image sensor,
It is.

  The technical significance and operational effects of conditional expression (10) are the same as in conditional expression (5). Note that IH is as described above.

Moreover, it is preferable to satisfy the following conditional expression (10-1) instead of conditional expression (10).
Conditional expression (10-1) 1.0 ≦ | f2 | /IH≦1.5

In the imaging apparatus of the present embodiment, preferably, the second lens group of the variable magnification optical system includes a first lens element, a second lens element, and a third lens element having positive refractive power in order from the object side. The first lens element has a convex shape on the object side, and satisfies the following conditional expression (6).
Conditional expression (6) -1.0 <(R2a-R2b) / (R2a + R2b) <1.0
However,
R2a is the radius of curvature of the object side surface of the second lens element,
R2b is the radius of curvature of the image side surface of the third lens element,
It is.

  The technical significance and operational effects of conditional expression (6) are as already described.

  Moreover, it is preferable to satisfy conditional expression (6-1) instead of conditional expression (6).

  In the imaging apparatus of the present embodiment, it is preferable that the second lens element and the third lens element of the variable power optical system have a positive refractive power and a negative refractive power, respectively.

  In the imaging apparatus according to the present embodiment, it is preferable that the fourth lens group of the variable magnification optical system includes a single lens element having a positive refractive power.

In the imaging apparatus of the present embodiment, preferably, the positive lens of the fourth lens group of the variable magnification optical system has a concave shape on the object side, and satisfies the following conditional expression (7).
Conditional Expression (7) 0 <(R4a−R4b) / (R4a + R4b) <1.0
However,
R4a is the radius of curvature of the object side surface of the positive lens in the fourth lens group,
R4b is the radius of curvature of the image side surface of the positive lens in the fourth lens group,
It is.

  The technical significance and operational effects of conditional expression (7) are as already described.

  Moreover, it is preferable to satisfy conditional expression (7-1) instead of conditional expression (7).

Hereinafter, Examples 1 to 11 using the variable magnification optical system of the present embodiment will be described.
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. 17 is a cross-sectional view of the variable power optical system of Example 5, FIG. 21 is a cross-sectional view of the variable power optical system of Example 6, and FIG. 24 is a sectional view of the variable magnification optical system, FIG. 27 is a sectional view of the variable magnification optical system of Example 8, FIG. 30 is a sectional view of the variable magnification optical system of Example 9, and FIG. A sectional view of the optical system is shown in FIG. 33, and a sectional view of the variable magnification optical system of Example 11 is shown in FIG. 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 Examples 1 and 2, the image height (IH) is 2.9 mm, and the pixel pitch of the image sensor is 1.4 μm. In Example 3, the image height (IH) is 2.25 mm, and the pixel pitch of the image sensor is 1.1 μm. However, in the following embodiments, the image height and the pixel pitch are not limited to these. For example, the pixel pitch may be 2.00 μm, 1.75 μm, 1.40 μm, 1.1 μm, and the like.
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.

Example 1
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 about 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 first lens element having a positive refractive power, a second lens element, and a third lens element. The first lens element has a convex shape on the object side. . Specifically, in order from the object side, the biconvex positive lens L21 serving as the first lens element, the aperture stop S, the biconvex positive lens L22 serving as the second lens element, and the biconvex positive lens L22 are joined. It is composed of a biconcave negative lens L23, which is a three-lens element, and 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.

Example 2
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 about 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 first lens element having a positive refractive power, a second lens element, and a third lens element. The first lens element has a convex shape on the object side. . Specifically, in order from the object side, the biconvex positive lens L21 serving as the first lens element, the aperture stop S, the biconvex positive lens L22 serving as the second lens element, and the biconvex positive lens L22 are joined. It is composed of a biconcave negative lens L23, which is a three-lens element, and 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 negative meniscus lens L3 having a concave surface facing the object side may be a negative meniscus lens having a convex surface facing the object side or a biconcave negative lens.

  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.

Example 3
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 about 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 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. ing.

  The second lens group includes, in order from the object side, a first lens element having a positive refractive power, a second lens element, and a third lens element, and the first lens element has a convex shape on the object side. Specifically, in order from the object side, the biconvex positive lens L21 serving as the first lens element, the aperture stop S, the biconvex positive lens L22 serving as the second lens element, and the biconvex positive lens L22 are joined. It is composed of a biconcave negative lens L23, which is a three-lens element, and has a positive refractive power as a whole and has a main zooming action.

  The third lens group includes 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 includes one positive meniscus lens L7 having a convex surface facing 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.
When focusing from the object point at infinity to the closest object point, both the second lens G2 and the third lens group G3 may be moved.

Example 4
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 about 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 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. ing.

  The second lens group includes, in order from the object side, a first lens element having a positive refractive power, a second lens element, and a third lens element, and the first lens element has a convex shape on the object side. Specifically, in order from the object side, both the biconvex positive lens L21 as the first lens element, the aperture stop S, the biconvex positive lens L22 as the second lens element, and the biconvex positive lens L22 are joined together. The lens is composed of a concave negative lens L23 serving as a third lens element, and has a positive refractive power as a whole and has a main zooming action.

  The third lens group includes 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 includes one positive meniscus lens L7 having a convex surface facing 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.
When focusing from the object point at infinity to the closest object point, both the second lens G2 and the third lens group G3 may be moved.

Example 5
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 about 13.5 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 facing the object side in a state of being joined to the biconcave negative lens L11. Has negative refractive power.
If the positive meniscus lens L12 is an energy curable resin, the first lens group G1 can be processed thinly, and a sufficient amount of movement of the second lens group G2 at the time of zooming can be secured, so that good performance is maintained. However, the overall length can be shortened.

  The second lens group G2 includes, in order from the object side, a first lens element having a positive refractive power, a second lens element, and a third lens element. The first lens element has a convex shape on the object side. . Specifically, in order from the object side, the biconvex positive lens L21 serving as the first lens element, the aperture stop S, the biconvex positive lens L22 serving as the second lens element, and the biconvex positive lens L22 are joined. It is composed of a biconcave negative lens L23 that is one lens element, and has a positive refractive power as a whole.

  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, 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.

Example 6
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 about 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 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 the positive meniscus lens L12 is an energy curable resin, the first lens group G1 can be processed thinly, and a sufficient amount of movement of the second lens group G2 at the time of zooming can be secured, so that good performance is maintained. However, the overall length can be shortened.

  The second lens group G2 includes, in order from the object side, a first lens element having a positive refractive power, a second lens element, and a third lens element. The first lens element has a convex shape on the object side. . Specifically, in order from the object side, the biconvex positive lens L21 serving as the first lens element, the aperture stop S, the biconvex positive lens L22 serving as the second lens element, and the biconvex positive lens L22 are joined. It is composed of a biconcave negative lens L23, which is a three-lens element, and 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, 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.

Example 7
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 about 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 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 the positive meniscus lens L12 is an energy curable resin, the first lens group G1 can be processed thinly, and a sufficient amount of movement of the second lens group G2 at the time of zooming can be secured, so that good performance is maintained. However, the overall length can be shortened.

  The second lens group G2 includes, in order from the object side, a first lens element having a positive refractive power, a second lens element, and a third lens element. The first lens element has a convex shape on the object side. . Specifically, in order from the object side, the biconvex positive lens L21 serving as the first lens element, the aperture stop S, the biconvex positive lens L22 serving as the second lens element, and the biconvex positive lens L22 are joined. It is composed of a biconcave negative lens L23, which is a three-lens element, and 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 negative meniscus lens L3 having a convex surface facing the object side may be a negative meniscus lens having a concave surface facing the object side, or a biconcave negative lens.

  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.

Example 8
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 about 13.5 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 facing the object side in a state of being joined to the biconcave negative lens L11. Has negative refractive power.
If the positive meniscus lens L12 is an energy curable resin, the first lens group G1 can be processed thinly, and a sufficient amount of movement of the second lens group G2 at the time of zooming can be secured, so that good performance is maintained. However, the overall length can be shortened.

  The second lens group G2 includes, in order from the object side, a first lens element having a positive refractive power, a second lens element, and a third lens element. The first lens element has a convex shape on the object side. . Specifically, in order from the object side, the biconvex positive lens L21 serving as the first lens element, the aperture stop S, the biconvex positive lens L22 serving as the second lens element, and the biconvex positive lens L22 are joined. It is composed of a biconcave negative lens L23, which is a three-lens element, and 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 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.

Example 9
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 about 14 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 is composed of one biconcave negative lens L1.

  The second lens group G2 includes, in order from the object side, a first lens element having a positive refractive power, a second lens element, and a third lens element. The first lens element has a convex shape on the object side. . Specifically, in order from the object side, a biconvex positive lens L21 serving as a first lens element, a L22 of a biconcave negative lens serving as a second lens element in a state of being joined to the biconvex positive lens L21, It is composed of a biconvex positive lens L23 that is a third lens element, and 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 negative meniscus lens L3 having a convex surface facing the object side may be a negative meniscus lens having a concave surface facing the object side, or a biconcave negative lens.

  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.

Example 10
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 about 10 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 first lens element having a positive refractive power, a second lens element, and a third lens element. The first lens element has a convex shape on the object side. . Specifically, in order from the object side, the biconvex positive lens L21 serving as the first lens element, the aperture stop S, the biconvex positive lens L22 serving as the second lens element, and the biconvex positive lens L22 are joined. It is composed of a biconcave negative lens L23, which is a three-lens element, and 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.

Example 11
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 about 10 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 first lens element having a positive refractive power, a second lens element, and a third lens element. The first lens element has a convex shape on the object side. . Specifically, in order from the object side, the biconvex positive lens L21 serving as the first lens element, the aperture stop S, the biconvex positive lens L22 serving as the second lens element, and the biconvex positive lens L22 are joined. It is composed of a biconcave negative lens L23, which is a three-lens element, and 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 negative meniscus lens L3 having a concave surface facing the object side may be a negative meniscus lens having a convex surface facing the object side or a biconcave negative lens.

  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 11. 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. Example 10 corresponds to Numerical Example 10. Example 11 corresponds to Numerical Example 11.
In the 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 vd 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.

  BF represents the distance from the lens final surface to the paraxial image surface in terms of air, and the total lens length represents the distance from the lens front surface to the lens final surface plus BF. On the other hand, BF # represents the distance from the final lens surface to the image plane in terms of air, and the total lens length # represents the distance from the frontmost lens surface to the final lens surface plus BF #.

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 * 24.9824 0.4982 1.90270 31.00 2.680
2 * 2.6593 0.5867 2.159
3 * 3.7965 0.6883 2.10223 16.77 2.159
4 * 5.9430 D4 2.120
5 * 2.1596 0.9525 1.59201 67.02 1.435
6 * -48.6138 0.2000 1.322
7 (Aperture) ∞ 0.0000 (Variable)
8 * 6.5103 0.6801 1.85135 40.10 1.201
9 -7.3491 0.5708 1.82114 24.06 1.134
10 * 5.5872 D10 1.015
11 * -4.6844 0.4504 1.77377 47.17 1.212
12 * 100.7637 D12 1.437
13 * -13.7627 0.8839 1.90270 31.00 2.801
14 * -5.1236 0.2065 2.866
15 ∞ 0.3000 1.51633 64.14 2.928
16 ∞ 0.4000 2.946
Image plane ∞

Aspheric data 1st surface
K = -397.963, A4 = 6.59381e-03, A6 = -1.17236e-03, A8 = 5.02427e-05
Second side
K = 0.088, A4 = -6.56207e-03, A6 = 3.84046e-03, A8 = -7.40701e-04
Third side
K = -7.634, A4 = -3.69106e-03, A6 = 1.79132e-03, A8 = -1.86618e-04
4th page
K = -23.212, A4 = -5.62260e-03, A6 = 5.95203e-04, A8 = -6.89594e-05
5th page
K = -0.956, A4 = 2.77532e-03, A6 = 7.11842e-04, A8 = 9.68824e-05
6th page
K = 218.608, A4 = -1.28903e-02, A6 = 7.79247e-03, A8 = -1.56315e-03
8th page
K = 0.801, A4 = -2.76409e-03, A6 = 7.97038e-03, A8 = -2.01303e-03
10th page
K = -38.926, A4 = 6.44034e-02, A6 = -6.22281e-03, A8 = 1.13101e-02
11th page
K = -3.245, A4 = 4.36822e-03, A6 = -5.62552e-03, A8 = -2.76127e-03
12th page
K = -575054.125, A4 = 1.94775e-02, A6 = -8.94047e-03, A8 = 3.15805e-04
Side 13
K = -0.780, A4 = 4.95196e-03, A6 = -1.14942e-03, A8 = 9.43150e-05
14th page
K = -2.819, A4 = 1.17394e-02, A6 = -2.72948e-03, A8 = 1.79738e-04

Various data

Zoom ratio 2.849

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

Focal length 3.754 6.019 10.695
FNO. 3.200 4.367 5.200
Angle of view 2ω 82.905 51.227 29.493
Image height 2.900 2.900 2.900
BF # 0.804 0.804 0.804
Total lens length # 12.898 12.898 12.898
Object distance ∞ ∞ ∞ 100.00 500.00 800.00
D4 3.931 2.207 0.200 3.137 2.256 0.534
D10 1.026 0.876 1.749 0.968 0.895 1.511
D12 1.626 3.500 4.633 2.478 3.432 4.537
Diaphragm diameter 0.983 0.983 1.210
Entrance pupil position 3.137 2.642 1.790
Exit pupil position -6.729 -16.061 -45.914
Front principal point position 5.032 6.511 10.036
Rear principal point position -3.308 -5.634 -10.298

Lens Start surface Focal length
L11 1 -3.332
L12 3 8.164
L21 5 3.517
L22 8 4.149
L23 9 -3.790
L3 11 -5.774
L4 13 8.624

Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 -5.700 1.773 0.255 -0.878
G2 5 3.194 2.403 -0.286 -1.548
G3 11 -5.774 0.450 0.011 -0.242
G4 13 8.624 0.884 0.706 0.263

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 -0.454 -0.602 -0.969 -0.539 -0.604 -0.889
G3 1.555 1.867 2.066 1.705 1.859 2.055
G4 0.932 0.939 0.937 0.930 0.937 0.934

Numerical Example 4
Surface data Unit mm

Surface number rd nd vd Effective diameter Surface ∞ ∞
1 * 32.5181 0.4000 1.90270 31.00 2.662
2 * 2.6859 0.5841 2.171
3 * 3.9263 0.7023 2.10223 16.77 2.172
4 * 6.3251 D4 2.123
5 * 2.3656 0.8877 1.59201 67.02 1.442
6 * -19.9615 0.2000 1.349
7 (Aperture) ∞ 0.0000 (Variable)
8 * 5.6753 0.6799 1.85135 40.10 1.257
9 -8.0095 0.5194 1.82114 24.06 1.184
10 * 5.2122 D10 1.039
11 * -4.7550 0.4439 1.77377 47.17 1.186
12 * 241.8954 D12 1.373
13 * -17.7526 1.0020 1.58347 30.25 2.836
14 * -5.0153 0.2387 2.891
15 ∞ 0.3000 1.51633 64.14 2.940
16 ∞ 0.4000 2.952
Image plane ∞

Aspheric data 1st surface
K = -204.602, A4 = 6.38593e-03, A6 = -1.31082e-03, A8 = 6.42265e-05
Second side
K = 0.140, A4 = -4.48908e-03, A6 = 3.35561e-03, A8 = -7.34479e-04
Third side
K = -8.010, A4 = -3.58577e-03, A6 = 2.02086e-03, A8 = -1.85601e-04
4th page
K = -27.131, A4 = -5.26129e-03, A6 = 7.06800e-04, A8 = -5.83212e-05
5th page
K = -1.224, A4 = -2.34964e-04, A6 = 1.88499e-08, A8 = 3.10798e-04
6th page
K = -178.856, A4 = -8.86247e-03, A6 = 7.81377e-03, A8 = -1.53400e-03
8th page
K = 6.120, A4 = 6.42116e-03, A6 = 8.89900e-03, A8 = -2.09052e-03
10th page
K = -38.050, A4 = 7.18749e-02, A6 = -5.04696e-03, A8 = 1.13516e-02
11th page
K = -3.616, A4 = 4.31319e-03, A6 = -1.04263e-03, A8 = -3.53360e-03
12th page
K = -1640587.993, A4 = 1.96904e-02, A6 = -4.81382e-03, A8 = -6.24215e-04
Side 13
K = -5.864, A4 = 5.12076e-03, A6 = -1.13861e-03, A8 = 9.49549e-05
14th page
K = -2.353, A4 = 1.15022e-02, A6 = -2.74683e-03, A8 = 1.78418e-04

Various data

Zoom ratio 2.850

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

Focal length 3.754 6.038 10.699
FNO. 3.200 4.349 5.200
Angle of view 2ω 82.899 51.642 29.898
Image height 2.900 2.900 2.900
BF # 0.837 0.837 0.837
Total lens length # 12.898 12.898 12.898
Object distance ∞ ∞ ∞ 100.00 500.00 800.00
D4 3.975 2.194 0.200 3.198 2.281 0.556
D10 1.006 0.888 1.793 0.960 0.900 1.528
D12 1.661 3.560 4.649 2.484 3.461 4.557
Diaphragm diameter 1.033 1.033 1.255
Entrance pupil position 3.012 2.510 1.668
Exit pupil position -5.919 -11.530 -20.540
Front principal point position 4.693 5.589 7.011
Rear principal point position -3.312 -5.686 -10.305

Lens Start surface Focal length
L11 1 -3.264
L12 3 8.143
L21 5 3.626
L22 8 3.993
L23 9 -3.778
L3 11 -6.022
L4 13 11.643

Zoom lens group data Group Start surface Group focal length Group composition length Front principal point position Rear principal point position
G1 1 -5.552 1.686 0.169 -0.919
G2 5 3.194 2.287 -0.238 -1.451
G3 11 -6.022 0.444 0.005 -0.245
G4 13 11.643 1.002 0.857 0.242

Group magnification
Wide angle Medium telephoto Wide angle (closest) Medium (closest) Telephoto (closest)
G1 0.000 0.000 0.000 0.053 0.011 0.007
G2 -0.455 -0.610 -0.986 -0.537 -0.607 -0.898
G3 1.571 1.870 2.058 1.707 1.857 2.046
G4 0.945 0.953 0.949 0.945 0.951 0.948

Numerical Example 5
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 6
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
BF 1.525 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 7
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 8
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 9
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 10
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 11
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
BF # 1.082 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-mentioned Example 1 (Numerical Example 1) to Example 11 (Numerical Example 11) in the above-mentioned conditional expressions (1) to (10) are shown.

Values taken by the examples in each conditional expression Conditional expression (1) Conditional expression (2) Conditional expression (3) Conditional expression (4) Conditional expression (5)
Example 1 24.06 2.47 42.96 0.90 0.50
Example 2 24.06 2.46 42.96 0.92 0.50
Example 3 31.00 2.29 42.96 0.90 0.50
Example 4 30.25 2.34 42.96 0.88 0.50
Example 5 24.06 2.30 29.43 0.96 0.53
Example 6 20.88 2.55 29.43 0.91 0.50
Example 7 24.06 2.70 25.46 0.94 0.44
Example 8 24.06 2.29 29.43 0.98 0.53
Example 9 25.63 2.67 23.61 0.89 0.45
Example 10 16.77 2.69 64.77 0.88 0.50
Example 11 15.00 3.00 66.54 0.83 0.46

Conditional expression (6) Conditional expression (7) Conditional expression (8) Conditional expression (9) Conditional expression (10)
Example 1 0.08 0.48 0.21 1.98 1.10
Example 2 0.10 0.50 0.21 2.01 1.10
Example 3 0.08 0.46 -0.13 1.97 1.10
Example 4 0.04 0.56 -0.08 1.91 1.10
Example 5 0.42 0.23 -0.09 2.53 1.40
Example 6 0.43 0.29 0.13 2.41 1.32
Example 7 0.16 0.78 0.05 2.48 1.17
Example 8 0.42 0.30 -0.10 2.58 1.39
Example 9 0.31 0.31 -0.02 2.36 1.19
Example 10 -0.02 0.24 0.61 1.91 1.09
Example 11 -0.72 0.24 0.81 1.80 0.99

  The zoom lens according to the present invention as described above can be used in an imaging device such as a digital camera or a video camera that performs imaging by forming an object image formed by the zoom lens on an imaging element such as a CCD. Specific examples are shown below.

  39, 40 and 41 are conceptual views showing the configuration of a digital camera using the present invention. FIG. 39 is a front perspective view showing the appearance of the digital camera, and FIG. 40 is a rear perspective view of the digital camera. FIG. 41 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 also includes a zoom lens 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 disposed on the upper part of the digital camera is pressed, photographing is performed through a zoom lens 7, for example, a zoom lens 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 image sensor, through the zoom lens 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 manner, the zoom lens 7 has a high magnification ratio and is small, so that good performance can be ensured and the digital camera can be miniaturized.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group L11, L12, L21, L22, L23, L3, L31, L32, L4, L41, L42 Lens element Lc Optical axis S Aperture stop CG Cover glass IM Imaging surface E Eyeball of observer 1 Shooting aperture 2 Viewfinder aperture 3 Flash light emitting unit 4 Shutter button 5 LCD monitor 6 Information input unit 7 Zoom lens 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 (11)

In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens group having a positive refractive power. Prepared,
The second lens group includes at least one positive lens and negative lens;
The fourth lens group includes a positive lens;
A variable magnification optical system characterized by satisfying the following conditional expressions (1), (2), and (3):
Conditional expression (1) 10 ≦ Vd4g ≦ 45
Conditional expression (2) 2.2 ≦ | α / f1 | + (α / f2) −0.026 × Vd4g ≦ 5.0
Conditional expression (3) 10 ≦ Vdmax−Vdmin ≦ 80
However,
α = (FLw × FLt) ^1/2
FLw is the focal length of the entire variable magnification optical system at the wide-angle end,
FLt is the focal length of the entire variable magnification optical system at the telephoto end,
f1 is the focal length of the first lens group,
f2 is the focal length of the second lens group,
Vd4g is the Abbe number with respect to the d-line of the positive lens in the fourth lens group,
Vdmax is the Abbe number for the d-line of the glass material having the lowest dispersion among the glass materials of the lenses of the second lens group,
Vdmin is the Abbe number for the d-line of the glass material having the highest dispersion among the glass materials of the lenses of the second lens group,
It is. The zoom lens system according to claim 1, wherein the following conditional expression (4) is satisfied.
Conditional expression (4) 0.45 ≦ | f1 | / (FLw × FLt) ^1/2 ≦ 1.60
However,
f1 is the focal length of the first lens group,
FLw is the focal length of the entire variable magnification optical system at the wide-angle end,
FLt is the focal length of the entire variable magnification optical system at the telephoto end,
It is. The zoom lens system according to claim 1 or 2, wherein the following conditional expression (5) is satisfied.
Conditional expression (5) 0.30 ≦ f2 / (FLw × FLt) ^1/2 ≦ 1.10.
However,
f2 is the focal length of the second lens group,
FLw is the focal length of the entire variable magnification optical system at the wide-angle end,
FLt is the focal length of the entire variable magnification optical system at the telephoto end,
It is. The second lens group includes, in order from the object side, a first lens element having a positive refractive power, a second lens element, and a third lens element.
The first lens element has a convex shape on the object side,
The zoom lens system according to any one of claims 1 to 3, wherein the following conditional expression (6) is satisfied.
Conditional expression (6) -1.0 <(R2a-R2b) / (R2a + R2b) <1.0
However,
R2a is the radius of curvature of the object side surface of the second lens element,
R2b is the radius of curvature of the image side surface of the third lens element,
It is. The positive lens of the fourth lens group has a concave shape on the object side,
The zoom lens system according to any one of claims 1 to 4, wherein the following conditional expression (7) is satisfied.
Conditional Expression (7) 0 <(R4a−R4b) / (R4a + R4b) <1.0
However,
R4a is the radius of curvature of the object side surface of the positive lens of the fourth lens group,
R4b is the radius of curvature of the image side surface of the positive lens in the fourth lens group,
It is.   An imaging apparatus comprising the variable magnification optical system according to claim 1 and an imaging element. A variable magnification optical system that forms an optical image of an object and an image sensor;
The imaging element converts an optical image formed by the variable magnification optical system into an electrical image signal,
The variable magnification optical system 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, a third lens group having a negative refractive power, and a positive refractive power. A fourth lens group having
The second lens group includes at least one positive lens and negative lens;
The fourth lens group includes a positive lens;
The imaging apparatus according to claim 6, wherein the following conditional expressions (1), (8), and (3) are satisfied.
Conditional expression (1) 10 ≦ Vd4g ≦ 45
Conditional Expression (8) −0.27 ≦ | IH / f1 | + (IH / f2) −0.05 × Vd4g ≦ 3.0
Conditional expression (3) 10 ≦ Vdmax−Vdmin ≦ 80
However,
IH is the image height of the image sensor,
f1 is the focal length of the first lens group,
f2 is the focal length of the second lens group,
Vd4g is the Abbe number with respect to the d-line of the positive lens in the fourth lens group,
Vdmax is the Abbe number for the d-line of the glass material having the lowest dispersion among the glass materials of the lenses of the second lens group,
Vdmin is the Abbe number for the d-line of the glass material having the highest dispersion among the glass materials of the lenses of the second lens group,
It is. The imaging apparatus according to claim 6 or 7, wherein the following conditional expression (9) is satisfied.
Conditional expression (9) 1.0 ≦ | f1 | /IH≦2.8
However,
f1 is the focal length of the first lens group,
IH is the image height of the image sensor,
is there. The image pickup apparatus according to claim 6, wherein the following conditional expression (10) is satisfied.
Conditional expression (10) 0.2 ≦ | f2 | /IH≦1.8
However,
f2 is the focal length of the second lens group,
IH is the image height of the image sensor,
It is. The second lens group includes, in order from the object side, a first lens element having a positive refractive power, a second lens element, and a third lens element.
The first lens element has a convex shape on the object side,
The image pickup apparatus according to claim 6, wherein the following conditional expression (6) is satisfied.
Conditional expression (6) -1.0 <(R2a-R2b) / (R2a + R2b) <1.0
However,
R2a is the radius of curvature of the object side surface of the second lens element,
R2b is the radius of curvature of the image side surface of the third lens element,
It is. The positive lens of the fourth lens group has a concave shape on the object side,
The image pickup apparatus according to claim 6, wherein the following conditional expression (7) is satisfied.
Conditional Expression (7) 0 <(R4a−R4b) / (R4a + R4b) <1.0
However,
R4a is the radius of curvature of the object side surface of the positive lens of the fourth lens group,
R4b is the radius of curvature of the image side surface of the positive lens in the fourth lens group,
It is.

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