JP2013218254A - Zoom lens, imaging apparatus and information processing apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and thin zoom lens having high imaging performance and an optical system with a large diameter, and provide an imaging apparatus and an information processing apparatus which use the zoom lens.SOLUTION: A zoom lens includes, in an order from an 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. In changing magnification, the first lens group is fixed, the second lens group is moved, the third lens group is moved, and the fourth lens group is fixed. The first lens group has a negative lens, a reflection optical element, and a positive lens in this order from the object side. The second lens group has a diaphragm, a positive lens, a cemented lens having a negative refractive power, and a positive lens in this order from the object side. The cemented lens has a positive lens and a negative lens.

Description

  The present invention relates to a zoom lens, an imaging apparatus using the same, and an information processing apparatus.

  In compact cameras, the number of pixels is increasing as the pixel pitch of the image sensor is reduced. If an attempt is made to improve the performance of the optical system corresponding to the narrowing of the pixel pitch, the influence of the diffraction limit cannot be ignored. In other words, the size of the light spot is larger than the size of the pixel. In order to eliminate such a state, it is necessary to increase the diameter of the optical system, that is, to reduce the F number. In order to increase the diameter of the optical system, it is also required that the optical system has high imaging performance and is small and thin.

  As an optical system having a relatively large aperture, for example, Patent Literature 1 and Patent Literature 2 disclose a bending variable magnification optical system (zoom lens system) configured by four lens groups. The bending 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 lens power. 4th lens group which has the refractive power of this. An optical element (prism) that bends the optical path is disposed in the first lens group.

  Here, the F number of the optical system at the wide-angle end is about 3.0 for the optical system of Patent Document 1 and about 3.4 for the optical system of Patent Document 2.

JP 2009-216941 A JP 2010-152143 A

  However, the optical systems of Patent Document 1 and Patent Document 2 cannot be said to have sufficiently achieved an increase in the diameter of the optical system.

  The present invention has been made in view of such a problem, and has a high imaging performance, a compact and thin zoom lens with a large optical system, and an imaging apparatus using the zoom lens And it aims at providing an information processor.

In order to solve the above-described problems and achieve the object, the zoom lens of the present invention includes:
From the object side,
A first lens group having negative refractive power;
A second lens group having a positive refractive power;
A third lens group having negative refractive power;
A fourth lens group having a positive refractive power,
During zooming, the first lens group is fixed, the second lens group is moved, the third lens group is moved, and the fourth lens group is fixed,
The first lens group includes, in order from the object side, a negative lens, a reflective optical element, and a positive lens.
The second lens group includes, in order from the object side, a stop, a positive lens, a cemented lens having negative refractive power, and a positive lens.
The cemented lens has a positive lens and a negative lens.

  The image pickup apparatus of the present invention includes a zoom lens and an image pickup element having an image pickup surface.

  According to the present invention, it is possible to provide a zoom lens having a high imaging performance, a small size, and a thin optical system with a large optical system, and an imaging apparatus and an information processing apparatus using the zoom lens.

FIG. 3 is a cross-sectional view along an optical axis showing an optical configuration when focusing on an object point at infinity of a zoom lens according to Example 1 of the present invention, where (a) is a wide-angle end, (b) is an intermediate, and (c) is telephoto. It is sectional drawing in an end. FIG. 3 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when focusing on an object point at infinity of the zoom lens according to Example 1; (D) is the wide-angle end, (e) to (h) are the middle, and (i) to (l) are the telephoto end. FIG. 4 is a cross-sectional view along an optical axis showing an optical configuration when focusing on an object point at infinity of a zoom lens according to Example 2 of the present invention, where (a) is a wide angle end, (b) is an intermediate, and (c) is telephoto. It is sectional drawing in an end. FIG. 6 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when the zoom lens according to Example 2 is focused on an object point at infinity. (D) is the wide-angle end, (e) to (h) are the middle, and (i) to (l) are the telephoto end. FIG. 6 is a cross-sectional view along the optical axis showing the optical configuration of the zoom lens according to Example 3 of the present invention when focusing on an object point at infinity, where (a) is a wide angle end, (b) is an intermediate, and (c) is telephoto. It is sectional drawing in an end. FIG. 6 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when the zoom lens according to Example 3 is focused on an object point at infinity. (D) is the wide-angle end, (e) to (h) are the middle, and (i) to (l) are the telephoto end. FIG. 6 is a cross-sectional view along an optical axis showing an optical configuration of a zoom lens according to Example 4 of the present invention when focusing on an object point at infinity, where (a) is a wide angle end, (b) is an intermediate, and (c) is telephoto. It is sectional drawing in an end. FIG. 10 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when focusing on an object point at infinity of a zoom lens according to Example 4; (D) is the wide-angle end, (e) to (h) are the middle, and (i) to (l) are the telephoto end. FIG. 10 is a cross-sectional view along the optical axis showing an optical configuration of a zoom lens according to Example 5 of the present invention when focusing on an object point at infinity, where (a) is a wide angle end, (b) is an intermediate, and (c) is telephoto. It is sectional drawing in an end. FIG. 10 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when focusing on an object point at infinity of a zoom lens according to Example 5; (D) is the wide-angle end, (e) to (h) are the middle, and (i) to (l) are the telephoto end. FIG. 10 is a cross-sectional view along an optical axis showing an optical configuration of a zoom lens according to Example 6 of the present invention when focusing on an object point at infinity, where (a) is a wide angle end, (b) is an intermediate, and (c) is telephoto. It is sectional drawing in an end. FIG. 10 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when focusing on an object point at infinity of a zoom lens according to Example 6; (D) is the wide-angle end, (e) to (h) are the middle, and (i) to (l) are the telephoto end. FIG. 10 is a cross-sectional view along the optical axis showing an optical configuration of a zoom lens according to Example 7 of the present invention when focusing on an object point at infinity, where (a) is a wide angle end, (b) is a middle, and (c) is telephoto. It is sectional drawing in an end. FIG. 10 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when focusing on an object point at infinity of a zoom lens according to Example 7; (D) is the wide-angle end, (e) to (h) are the middle, and (i) to (l) are the telephoto end. It is a figure which shows a mode that an off-axis light ray passes an air lens, and angle (alpha) and (beta). It is a front perspective view which shows the external appearance of the digital camera 140 incorporating the zoom lens by this invention. 2 is a rear perspective view of the digital camera 140. FIG. 2 is a cross-sectional view showing an optical configuration of a digital camera 140. FIG. 1 is a front perspective view of a state in which a cover of a personal computer 300 that is an example of an information processing apparatus in which a zoom lens of the present invention is incorporated as an objective optical system is opened. FIG. 2 is a cross-sectional view of a photographing optical system 303 of a personal computer 300. FIG. 2 is a side view of a personal computer 300. FIG. 1A and 1B are diagrams showing a mobile phone as an example of an information processing apparatus in which a zoom lens according to the present invention is incorporated as a photographing optical system, where FIG. 3A is a front view of the mobile phone 400, FIG. 2 is a cross-sectional view of a photographing optical system 405. FIG. It is a block diagram which shows the structure of the process part of information processing apparatus. It is a block diagram which shows the structure of the process part of a mobile telephone.

  Hereinafter, embodiments and examples of a zoom lens, an imaging apparatus, and an information processing apparatus according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment and an Example. A lens having a positive paraxial focal length is defined as a positive lens, and a lens having a negative paraxial focal length is defined as a negative lens. In the following description, the optical system means a zoom lens.

  The zoom lens of this 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 power. And a fourth lens group having a refractive power of 1 at the time of zooming, the first lens group is fixed, the second lens group is moved, the third lens group is moved, and the fourth lens group is fixed. The first lens group includes, in order from the object side, a negative lens, a reflective optical element, and a positive lens. The second lens group includes, in order from the object side, a stop, a positive lens, and a negative lens. It has a cemented lens having a refractive power and a positive lens, and the cemented lens has a positive lens and a negative lens.

  In the zoom lens according to the present embodiment, the lens group has a negative leading configuration, that is, a configuration in which the refractive power of the first lens group is negative. At the time of zooming, the second lens group and the third lens group are moved, and the first lens group and the fourth lens group are fixed (stationary). Here, the second lens group and the third lens group are preferably moved in the same direction. For example, when both the second lens group and the third lens group are moved to the object side, the third lens group can be positioned in the space after the second lens group has moved. Thus, since one space can be shared by a plurality of lens groups, the overall length of the optical system can be shortened.

  The first lens group includes, in order from the object side, a negative lens, a reflective optical element, and a positive lens. With such a configuration, the entrance pupil position can be brought closer to the object side, so that the outer diameter of the first lens group can be reduced. As a result, it is possible to maintain both good imaging performance and make the optical system thinner. The reflective optical element is a prism or a mirror and is used to bend the optical path.

  The second lens group includes, in order from the object side, a stop (aperture stop), a positive lens, a cemented lens having a negative refractive power, and a positive lens. The cemented lens includes a positive lens and a negative lens. Has a lens.

  In the vicinity of the stop, spherical aberration and coma are likely to occur. Therefore, the second lens group located in the vicinity of the stop is configured as described above to suppress the occurrence of spherical aberration and coma. As a result, it is possible to increase the diameter of the optical system while maintaining good imaging performance.

  Further, since the diaphragm moves together with the second lens group at the time of zooming, the F number of the optical system varies with zooming. Since the third lens unit also moves during zooming, the third lens unit also affects the F number variation. Here, if the refractive power of the second lens group is large, the fluctuation of the F number mainly depends on the second lens group. Therefore, by increasing the refractive power of the second lens group, it is possible to reduce the influence on the F-number fluctuation due to the movement of the third lens group.

  In the zoom lens of the present embodiment, the second lens group is configured as described above, so that the refractive power of the second lens group can be increased while suppressing the occurrence of spherical aberration and coma. As a result, it is possible to reduce the variation in the composite focal length of the lens group on the image side (lens group after the second lens group) from the stop. It becomes possible to reduce the fluctuation of the number.

The zoom lens according to the present embodiment preferably satisfies the following conditional expression (1).
1.1 ≦ φ _1o / φ _2o ≦ 1.8 (1)
here,
φ _1o is half the effective aperture on the lens surface closest to the object side of the first lens group,
φ _2o is half the effective aperture of the lens surface closest to the object side of the second lens group,
It is.

  When the diameter of the optical system is increased, the diameter of the second lens group including the stop is increased, so that the thickness of the entire optical system is increased. If the optical system is widened to avoid this, the aperture diameter can be reduced with the same F number. However, on the other hand, since the first lens unit becomes larger as the angle of view becomes wider, the thickness of the entire optical system becomes thicker. Therefore, it is desirable to satisfy the conditional expression (1) in order to achieve both a large aperture and a small size of the optical system. In particular, it is desirable for the bending optical system to satisfy the conditional expression (1). The effective aperture means the maximum diameter of the light beam that passes through the lens surface.

  If the upper limit value of conditional expression (1) is exceeded, the thickness of the second lens group becomes thick. On the other hand, if the lower limit of conditional expression (1) is not reached, the thickness of the first lens group becomes thick. Therefore, in either case, the entire optical system becomes large.

In addition, it is preferable to satisfy the following conditional expression (1 ′) instead of conditional expression (1).
1.3 ≦ φ _1o / φ _2o ≦ 1.6 (1 ′)
Furthermore, it is better to satisfy the following conditional expression (1 ″) instead of conditional expression (1).
1.4 ≦ φ _1o / φ _2o ≦ 1.5 (1 ″)

In the zoom lens according to the present embodiment, it is preferable that the third lens group includes a positive lens and a negative lens and satisfies the following conditional expression (2).
0 ≦ n _3p −n _3n ≦ 0.20 (2)
here,
n _3p is the refractive index at the d-line of the positive lens in the third lens group,
n _3n is the refractive index at the d-line of the negative lens of the third lens group,
It is.

  The third lens group has a positive lens and a negative lens. Therefore, when the two lenses are arranged separately, an air lens La is formed between the two lenses, for example, as shown in FIG. In FIG. 15, the lens Lo on the object side is a positive lens, and the lens Li on the image side is a negative lens. Α and β are angles formed by the off-axis rays and the normal of the lens surface, respectively. Here, α is an angle on the image side lens surface of the lens Lo on the object side, and β is an angle on the object side of the lens Li on the image side. The object side lens Lo may be a negative lens, and the image side lens Li may be a positive lens.

  Here, if Δα and Δβ are the minute change amounts of α and β, and | Δα−Δβ | is the difference between the minute change amounts, | Δα−Δβ | is smaller as the difference between the refractive indexes of the two lenses is smaller. Therefore, if the difference in refractive index between the two lenses is made small, | Δα−Δβ | can be suppressed to a small value even if decentration occurs between the two lenses. As a result, it is possible to reduce a decrease in imaging performance of the optical system.

  In particular, in a large aperture optical system, since the depth of focus becomes shallow, if the eccentricity occurs, the imaging performance tends to deteriorate. Therefore, it is important how to reduce the sensitivity to the eccentricity error. By satisfying conditional expression (2), it is possible to reduce the sensitivity to the eccentricity error.

  If the upper limit value of conditional expression (2) is exceeded, the difference in refractive index between the positive lens and the negative lens becomes too large, and the sensitivity to decentration error increases. As a result, astigmatism and field curvature increase. On the other hand, if the lower limit value of conditional expression (2) is not reached, the Petzval sum becomes large, so that the field curvature becomes large. As a result, the imaging performance of the optical system is degraded.

Note that the following conditional expression (2 ′) may be satisfied instead of conditional expression (2).
0 ≦ n _3p −n _3n ≦ 0.15 (2 ′)
Furthermore, it is more preferable to satisfy the following conditional expression (2 ″) instead of conditional expression (2).
0 ≦ n _3p −n _3n ≦ 0.12 (2 ″)

In addition, it is preferable that the zoom lens according to the present embodiment satisfies the following conditional expression (3).
1.8 ≦ Δ _2G / φ _1o ≦ 2.6 (3)
here,
Δ _2G is the amount of movement of the second lens group when moving from the wide-angle end to the telephoto end,
φ _1o is half the effective aperture on the lens surface closest to the object side of the first lens group,
It is.

  As described above, the F number varies with zooming. If the F number fluctuates greatly, the F number at the telephoto end increases, and the resolution at the telephoto end decreases. Therefore, it is desirable to make the amount of movement of the second lens group appropriate, that is, satisfy the conditional expression (3).

  If the upper limit of conditional expression (3) is exceeded, the amount of movement of the second lens group becomes too large with respect to the effective aperture of the first lens group. In this case, since the fluctuation of the F number becomes large, a high resolving power cannot be obtained at the telephoto end. On the other hand, if the lower limit of conditional expression (3) is not reached, the amount of movement of the second lens group will be small, but the refractive power of the second lens group will be large, and the amount of spherical aberration and coma generated will increase. As a result, the imaging performance of the optical system is degraded.

It should be noted that the following conditional expression (3 ′) is preferably satisfied instead of conditional expression (3).
1.9 ≦ Δ _2G / φ _1o ≦ 2.4 (3 ′)
Furthermore, it is better to satisfy the following conditional expression (3 ″) instead of conditional expression (3).
2.0 ≦ Δ _2G / φ _1o ≦ 2.2 (3 ″)

In the zoom lens according to the present embodiment, it is preferable that the third lens group includes an object side lens and an image side lens, and satisfies the following conditional expression (4).
−0.4 ≦ (r _3oi −r _3io ) / (r _3oi + r _3io ) ≦ 0.4 (4)
here,
r _3oi is the paraxial radius of curvature of the image side surface of the lens on the object side of the third lens group,
r _3io is the paraxial radius of curvature of the object side surface of the lens on the image side of the third lens group,
It is.

  As described in the conditional expression (2), in order to reduce the sensitivity to the eccentricity error, it is preferable to reduce the difference | Δα−Δβ | Here, as the difference in paraxial radius of curvature between the object side lens and the image side lens is smaller, | Δα−Δβ | can be reduced. Therefore, if the difference between the paraxial radii of curvature of the two lenses is reduced, | Δα−Δβ | can be suppressed to a small value even if an eccentricity occurs between the two lenses. As a result, it is possible to reduce a decrease in imaging performance of the optical system.

  If the upper limit value of conditional expression (4) is exceeded or falls below the lower limit value, the difference between the paraxial radii of curvature of the two lens surfaces becomes too large, making it difficult to reduce the sensitivity to eccentricity errors. As a result, the imaging performance of the optical system is degraded.

It should be noted that the following conditional expression (4 ′) may be satisfied instead of conditional expression (4).
−0.3 ≦ (r _3oi −r _3io ) / (r _3oi + r _3io ) ≦ 0.3 (4 ′)
Furthermore, it is more preferable that the following conditional expression (4 ″) is satisfied instead of conditional expression (4).
−0.2 ≦ (r _3oi −r _3io ) / (r _3oi + r _3io ) ≦ 0.25 (4 ″)

In addition, it is preferable that the zoom lens according to the present embodiment satisfies the following conditional expression (5).
n _ave ≦ 1.75 (5)
here,
n _ave is an average value of refractive indexes obtained from all the lenses located on the image side of the first lens group,
It is.

  As described above, since the depth of focus is small in an optical system with a large aperture, it can be said that the sensitivity to manufacturing errors is high. Here, the manufacturing error is, for example, an error in the shape (curvature radius, swell) of the lens surface at the time of manufacturing. If an error occurs in the shape of the lens surface, the imaging performance is degraded. The degradation in imaging performance due to this error is greater as the refractive index of the lens is higher. Therefore, it is preferable that the conditional expression (5) is satisfied.

  By satisfying conditional expression (5), the overall refractive index of the lens located on the image side with respect to the stop is reduced. As a result, the number of lenses with low sensitivity to the shape error of the lens surface increases, so that it is possible to reduce the deterioration of the imaging performance of the optical system.

It should be noted that the following conditional expression (5 ′) should be satisfied instead of conditional expression (5).
n _ave ≦ 1.70 (5 ′)
Furthermore, it is more preferable to satisfy the following conditional expression (5 ″) instead of conditional expression (5).
n _ave ≦ 1.65 (5 ″)

The zoom lens according to the present embodiment preferably satisfies the following conditional expression (6).
0.7 ≦ Δ _3G / Δ _2G ≦ 1.2 (6)
here,
Δ _2G is the amount of movement of the second lens group when moving from the wide-angle end to the telephoto end,
Δ _3G is the amount of movement of the third lens group when moving from the wide-angle end to the telephoto end,
It is.

  By satisfying conditional expression (6), it is possible to reduce the fluctuation of the F number accompanying zooming.

  If the upper limit of conditional expression (6) is exceeded, the amount of movement of the third lens group at the time of zooming becomes too large. On the other hand, if the lower limit of conditional expression (6) is not reached, the amount of movement of the second lens group during zooming becomes too large. If the amount of movement of the second lens group or the third lens group becomes too large, the fluctuation of the composite focal length of the lens group on the image side with respect to the stop becomes large, so that the fluctuation of the F number becomes large.

It should be noted that the following conditional expression (6 ′) may be satisfied instead of conditional expression (6).
0.80 ≦ Δ _3G / Δ _2G ≦ 1.1 (6 ′)
Furthermore, it is more preferable that the following conditional expression (6 ″) is satisfied instead of conditional expression (6).
0.85 ≦ Δ _3G / Δ _2G ≦ 1.0 (6 ″)

The zoom lens according to the present embodiment preferably satisfies the following conditional expression (7).
−10 ≦ f _1i / f _1o ≦ −2 (7)
here,
f _1o is the focal length of the lens on the object side of the first lens group,
f _1i is the focal length of the image side lens of the first lens group,
It is.

  Conditional expression (7) is a preferable condition for achieving both the size of the first lens unit and aberration correction in a well-balanced manner while having a large aperture optical system.

  If the upper limit value of conditional expression (7) is exceeded, the focal length of the lens closest to the image side becomes too short, and the occurrence of chromatic aberration of magnification at the wide angle end becomes large. As a result, the resolution is lowered at the wide-angle end. On the other hand, if the lower limit of conditional expression (7) is not reached, the focal length of the lens closest to the image side becomes too long, and the first lens group becomes large.

It should be noted that the following conditional expression (7 ′) may be satisfied instead of conditional expression (7).
−8 ≦ f _1i / f _1o ≦ −4 (7 ′)
Furthermore, it is better to satisfy the following conditional expression (7 ″) instead of conditional expression (7).
−7 ≦ f _1i / f _1o ≦ −5 (7 ″)

The zoom lens according to the present embodiment preferably satisfies the following conditional expression (8).
−1.5 ≦ f ₁ / (f _w × f _t ) ^1/2 ≦ −0.7 (8)
here,
f ₁ is the focal length of the first lens group,
f _w is the focal length of the entire zoom lens system at the wide-angle end,
f _t is the focal length of the entire zoom lens system at the telephoto end,
It is.

  Conditional expression (8) is a preferable conditional expression for suppressing the occurrence of spherical aberration, coma aberration, and lateral chromatic aberration, although the optical system has a large aperture.

  When the upper limit value of conditional expression (8) is exceeded, the focal length of the first lens unit becomes too short (refractive power is too large) with respect to the zoom magnification. As a result, the height of light incident on the lens group on the image side with respect to the stop becomes high, so that spherical aberration and coma are likely to occur. It is also disadvantageous for thinning. Furthermore, the F number at the telephoto end becomes large. On the other hand, if the lower limit of conditional expression (8) is not reached, the focal length of the first lens group becomes too long (refractive power is too small) with respect to the zoom magnification. As a result, it becomes impossible to sufficiently correct coma and lateral chromatic aberration that occur in the lens group on the image side of the stop.

It should be noted that the following conditional expression (8 ′) should be satisfied instead of conditional expression (8).
−1.3 ≦ f ₁ / (f _w × f _t ) ^1/2 ≦ −0.9 (8 ′)
Further, it is more preferable that the following conditional expression (8 ″) is satisfied instead of conditional expression (8).
−1.2 ≦ f ₁ / (f _w × f _t ) ^1/2 ≦ −1.0 (8 ″)

The zoom lens according to the present embodiment preferably satisfies the following conditional expression (9).
0.5 ≦ f ₂ / (f _w × f _t ) ^1/2 ≦ 1.5 (9)
here,
f ₂ is the focal length of the second lens group,
f _w is the focal length of the entire zoom lens system at the wide-angle end,
f _t is the focal length of the entire zoom lens system at the telephoto end,
It is.

  Conditional expression (9) is a preferable conditional expression for suppressing the fluctuation of the F-number due to zooming and suppressing the occurrence of spherical aberration and coma.

  If the upper limit value of conditional expression (9) is exceeded, the focal length of the second lens group becomes too long (refractive power is too small) with respect to the zoom magnification. As a result, the amount of movement of the second lens group at the time of zooming increases, so that the F-number fluctuations accompanying zooming increase. Further, it becomes difficult to reduce the size of the optical system, and the F number at the telephoto end increases. On the other hand, if the lower limit value of conditional expression (9) is not reached, the focal length of the second lens group becomes too short (refractive power becomes large) with respect to the zoom magnification, so that spherical aberration and coma aberration occur.

It should be noted that the following conditional expression (9 ′) should be satisfied instead of conditional expression (9).
0.6 ≦ f ₂ / (f _w × f _t ) ^1/2 ≦ 1.4 (9 ′)
Furthermore, it is more preferable that the following conditional expression (9 ″) is satisfied instead of conditional expression (9).
0.7 ≦ f ₂ / (f _w × f _t ) ^1/2 ≦ 1.3 (9 ″)

In the zoom lens according to the present embodiment, it is preferable that the following conditional expression (10) is satisfied.
_{0.53 ≦ (Fno w × Fno t} ) 1/2 / (f w × f t) 1/2 ≦ 0.65 (10)
here,
Fno _w is, F-number of the zoom lens at the wide-angle end,
Fno _t is, F-number of the zoom lens at the telephoto end,
f _w is the focal length of the entire zoom lens system at the wide-angle end,
f _t is the focal length of the entire zoom lens system at the telephoto end,
It is.

  If the F-number variation due to zooming is large, the F-number at the telephoto end becomes large, resulting in a decrease in resolution at the telephoto end. Therefore, it is desirable to satisfy conditional expression (10).

  If the upper limit value of conditional expression (10) is exceeded, the F number at the telephoto end becomes too large, which causes a reduction in resolution at the telephoto end. On the other hand, if the lower limit of conditional expression (10) is not reached, the F number at the wide-angle end becomes too small, and the depth of focus becomes too shallow. As a result, as described in conditional expression (5), the resolving power is reduced due to manufacturing errors.

Note that the following conditional expression (10 ′) is preferably satisfied instead of conditional expression (10).
_{0.54 ≦ (Fno w × Fno t} ) 1/2 / (f w × f t) 1/2 ≦ 0.63 (10 ')
Furthermore, it is more preferable that the following conditional expression (10 ″) is satisfied instead of conditional expression (10).
0.55 ≦ (Fno _w × Fno _t ) ^1/2 / (f _w × f _t ) ^1/2 ≦ 0.62 (10 ″)

  In the zoom lens according to the present embodiment, it is preferable that the fourth lens group includes one resin lens.

  In the zoom lens according to the present embodiment, it is preferable that the diameter of the diaphragm is constant during zooming.

  Further, an imaging apparatus according to the present embodiment includes the zoom lens and an imaging element having an imaging surface.

  Note that the zoom lens may be composed of only four lens groups (first lens group to fourth lens group). Further, the first lens group may be composed of only one negative lens, one reflective optical element, and one positive lens in order from the object side. In addition, the second lens group may include only an aperture (aperture stop), one positive lens, one cemented lens, and one positive lens in order from the object side. Further, the third lens group may be composed of only one positive lens and one negative lens.

  Embodiments of the zoom lens according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  A zoom lens according to Example 1 of the present invention will be described. FIG. 1 is a cross-sectional view (lens cross-sectional view) along the optical axis showing the optical configuration of the zoom lens according to Example 1 of the present invention when focusing on an object point at infinity, (a) is a wide-angle end, and (b). Is an intermediate focal length state, and (c) is a sectional view at the telephoto end. In all the following examples, in the lens cross-sectional views, C represents a cover glass, and I represents an imaging surface of an imaging device.

  FIG. 2 is an aberration diagram of the zoom lens according to Example 1 when focusing on an object point at infinity, where “ω” is a half angle of view. The symbols in the aberration diagrams are the same in the examples described later.

  In these aberration diagrams, (a), (b), (c), and (d) are spherical aberration (SA), astigmatism (AS), distortion (DT), and magnification at the wide-angle end, respectively. Chromatic aberration (CC) is shown.

  Further, (e), (f), (g), and (h) are respectively spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) in the intermediate focal length state. Is shown.

  Further, (i), (j), (k), and (l) respectively indicate spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) at the telephoto end. ing.

  As shown in FIG. 1, the zoom lens of Example 1 includes, in order from the object side, a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power. And a third lens group G3 having a negative refractive power 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 L1 having a convex surface facing the object side, a reflective optical element L2, and a positive meniscus lens L3 having a convex surface facing the object side.

  The second lens group G2 includes, in order from the object side, a biconvex positive lens L4, a biconvex positive lens L5, a biconcave negative lens L6, and a biconvex positive lens L7. Here, the biconvex positive lens L5 and the biconcave negative lens L6 are cemented.

  The aperture stop S is located between the object side surface and the image side surface of the biconvex positive lens L4. Even if the aperture stop is in such a position, it is considered that the aperture stop is located closer to the object side than the second lens G2.

  The third lens group G3 includes a positive meniscus lens L8 having a convex surface directed toward the image side, and a biconcave negative lens L9.

  The fourth lens group G4 includes a biconvex positive lens L10.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed (stationary), the second lens group G2 moves to the object side, the third lens group G3 moves to the object side, The four lens group G4 is fixed (stationary).

  The aspheric surfaces are the image side surface of the negative meniscus lens L1, the both sides of the biconvex positive lens L4, the image side surface of the biconvex positive lens L7, the image side surface of the positive meniscus lens L8, and the object side surface of the biconcave negative lens L9. And a total of 8 surfaces including both surfaces of the biconvex positive lens L10.

  Next, a zoom lens according to embodiment 2 will be described. FIG. 3 is a cross-sectional view along the optical axis showing the optical configuration of the imaging optical system according to the second embodiment at the time of focusing on an object point at infinity, and FIG. 4 shows the imaging optical system according to the second embodiment at the time of focusing on an object point at infinity. FIG.

  As shown in FIG. 3, the zoom lens of Example 2 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power. And a third lens group G3 having a negative refractive power 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 L1 having a convex surface facing the object side, a reflective optical element L2, and a positive meniscus lens L3 having a convex surface facing the object side.

  The second lens group G2 includes, in order from the object side, a biconvex positive lens L4, a biconvex positive lens L5, a biconcave negative lens L6, and a biconvex positive lens L7. Here, the biconvex positive lens L5 and the biconcave negative lens L6 are cemented.

  The third lens group G3 includes a positive meniscus lens L8 having a convex surface directed toward the image side, and a biconcave negative lens L9.

  The fourth lens group G4 includes a biconvex positive lens L10.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed (stationary), the second lens group G2 moves to the object side, the third lens group G3 moves to the object side, The four lens group G4 is fixed (stationary).

  The aspherical surface includes the image side surface of the negative meniscus lens L1, both surfaces of the biconvex positive lens L4, both surfaces of the biconvex positive lens L7, the image side surface of the positive meniscus lens L8, and the object side surface of the biconcave negative lens L9. A total of nine surfaces including both surfaces of the biconvex positive lens L10 are provided.

  Next, a zoom lens according to embodiment 3 will be described. FIG. 5 is a cross-sectional view along the optical axis showing the optical configuration of the imaging optical system according to the third embodiment at the time of focusing on an object point at infinity. FIG. 6 shows the imaging optical system according to the third embodiment at the time of focusing on an object point at infinity. FIG.

  As shown in FIG. 5, the zoom lens of Example 3 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power. And a third lens group G3 having a negative refractive power 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 L1 having a convex surface facing the object side, a reflective optical element L2, and a positive meniscus lens L3 having a convex surface facing the object side.

  The second lens group G2, in order from the object side, includes a biconvex positive lens L4, a positive meniscus lens L5 having a convex surface facing the object side, a negative meniscus lens L6 having a convex surface facing the object side, and a biconvex positive lens L7. And is composed of. Here, the positive meniscus lens L5 and the negative meniscus lens L6 are cemented.

  The third lens group G3 includes a positive meniscus lens L8 having a convex surface directed toward the image side, and a biconcave negative lens L9.

  The fourth lens group G4 includes a biconvex positive lens L10.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed (stationary), the second lens group G2 moves to the object side, the third lens group G3 moves to the object side, The four lens group G4 is fixed (stationary).

  The aspherical surface includes the image side surface of the negative meniscus lens L1, both surfaces of the biconvex positive lens L4, both surfaces of the biconvex positive lens L7, the image side surface of the positive meniscus lens L8, and the object side surface of the biconcave negative lens L9. A total of nine surfaces including both surfaces of the biconvex positive lens L10 are provided.

  Next, a zoom lens according to embodiment 4 will be described. FIG. 7 is a cross-sectional view along the optical axis showing the optical configuration of the imaging optical system according to the fourth embodiment when focusing on an object point at infinity, and FIG. 8 is when focusing on an object point at infinity of the imaging optical system according to the fourth embodiment. FIG.

  As shown in FIG. 7, the zoom lens of Example 4 includes, in order from the object side, a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power. And a third lens group G3 having a negative refractive power 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 L1 having a convex surface facing the object side, a reflective optical element L2, and a positive meniscus lens L3 having a convex surface facing the object side.

  The second lens group G2, in order from the object side, includes a biconvex positive lens L4, a positive meniscus lens L5 having a convex surface facing the object side, a negative meniscus lens L6 having a convex surface facing the object side, and a biconvex positive lens L7. And is composed of. Here, the positive meniscus lens L5 and the negative meniscus lens L6 are cemented.

  The third lens group G3 includes a negative meniscus lens L8 having a convex surface directed toward the object side, and a positive meniscus lens L9 having a convex surface directed toward the object side.

  The fourth lens group G4 includes a biconvex positive lens L10.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed (stationary), the second lens group G2 moves to the object side, the third lens group G3 moves to the object side, The four lens group G4 is fixed (stationary).

  The aspherical surfaces include the image side surface of the negative meniscus lens L1, both surfaces of the biconvex positive lens L4, both surfaces of the biconvex positive lens L7, the image side surface of the negative meniscus lens L8, the object side surface of the positive meniscus lens L9, both A total of nine surfaces including both surfaces of the convex positive lens L10 are provided.

  Next, a zoom lens according to embodiment 5 will be described. FIG. 9 is a cross-sectional view along the optical axis showing the optical configuration of the imaging optical system according to the fifth embodiment at the time of focusing on an object point at infinity, and FIG. 10 shows the imaging optical system according to the fifth embodiment at the time of focusing on an object point at infinity. FIG.

  As shown in FIG. 9, the zoom lens of Example 5 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power. And a third lens group G3 having a negative refractive power 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 L1 having a convex surface facing the object side, a reflective optical element L2, and a positive meniscus lens L3 having a convex surface facing the object side.

  The second lens group G2, in order from the object side, includes a biconvex positive lens L4, a positive meniscus lens L5 having a convex surface facing the object side, a negative meniscus lens L6 having a convex surface facing the object side, and a biconvex positive lens L7. And is composed of. Here, the positive meniscus lens L5 and the negative meniscus lens L6 are cemented.

  The third lens group G3 includes a negative meniscus lens L8 having a convex surface directed toward the object side, and a positive meniscus lens L9 having a convex surface directed toward the object side.

  The fourth lens group G4 includes a biconvex positive lens L10.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed (stationary), the second lens group G2 moves to the object side, the third lens group G3 moves to the object side, The four lens group G4 is fixed (stationary).

  The aspherical surfaces include the image side surface of the negative meniscus lens L1, both surfaces of the biconvex positive lens L4, both surfaces of the biconvex positive lens L7, the image side surface of the negative meniscus lens L8, the object side surface of the positive meniscus lens L9, both A total of nine surfaces including both surfaces of the convex positive lens L10 are provided.

  Next, a zoom lens according to embodiment 6 will be described. FIG. 11 is a cross-sectional view along the optical axis showing the optical configuration of the imaging optical system according to the sixth embodiment when focusing on an object point at infinity, and FIG. FIG.

  As shown in FIG. 11, the zoom lens of Example 6 includes, in order from the object side, a first lens group G1 having a negative refractive power, an aperture stop S, and a second lens group G2 having a positive refractive power. And a third lens group G3 having a negative refractive power 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 L1, a reflective optical element L2, and a positive meniscus lens L3 having a convex surface facing the object side.

  The second lens group G2, in order from the object side, includes a biconvex positive lens L4, a positive meniscus lens L5 having a convex surface facing the object side, a negative meniscus lens L6 having a convex surface facing the object side, and a biconvex positive lens L7. And is composed of. Here, the positive meniscus lens L5 and the negative meniscus lens L6 are cemented.

  The third lens group G3 includes a positive meniscus lens L8 having a convex surface directed toward the image side, and a biconcave negative lens L9.

  The fourth lens group G4 includes a biconvex positive lens L10.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed (stationary), the second lens group G2 moves to the object side, the third lens group G3 moves to the object side, The four lens group G4 is fixed (stationary).

  The aspherical surfaces include both sides of the biconcave negative lens L1, both sides of the biconvex positive lens L4, both sides of the biconvex positive lens L7, both sides of the positive meniscus lens L8, both sides of the biconcave negative lens L9, and biconvex. A total of 12 surfaces including both surfaces of the positive lens L10 are provided.

  Next, a zoom lens according to embodiment 7 will be described. FIG. 13 is a cross-sectional view along the optical axis showing the optical configuration of the imaging optical system according to the seventh embodiment when focusing on an object point at infinity, and FIG. 14 is when focusing on an object point at infinity of the imaging optical system according to the seventh embodiment. FIG.

  As shown in FIG. 13, the zoom lens of Example 7 includes, in order from the object side, a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power. And a third lens group G3 having a negative refractive power 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 L1, a reflective optical element L2, and a positive meniscus lens L3 having a convex surface facing the object side.

  The second lens group G2, in order from the object side, includes a biconvex positive lens L4, a positive meniscus lens L5 having a convex surface facing the object side, a negative meniscus lens L6 having a convex surface facing the object side, and a biconvex positive lens L7. And is composed of. Here, the positive meniscus lens L5 and the negative meniscus lens L6 are cemented.

  The third lens group G3 includes a positive meniscus lens L8 having a convex surface directed toward the image side, and a biconcave negative lens L9.

  The fourth lens group G4 includes a biconvex positive lens L10.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed (stationary), the second lens group G2 moves to the object side, the third lens group G3 moves to the object side, The four lens group G4 is fixed (stationary).

  The aspherical surfaces include both sides of the biconcave negative lens L1, both sides of the biconvex positive lens L4, both sides of the biconvex positive lens L7, both sides of the positive meniscus lens L8, both sides of the biconcave negative lens L9, and biconvex. A total of 12 surfaces including both surfaces of the positive lens L10 are provided.

  Next, numerical data of optical members constituting the zoom lens of each of the above embodiments will be listed. In the numerical data of each embodiment, r1, r2,... Are the curvature radii of the lens surfaces, d1, d2,... Are the thickness or air spacing of each lens, and nd1, nd2,. Are the Abbe number of each lens, and * is an aspherical surface. WE is the wide-angle end, ST is the intermediate focal length state, TE is the telephoto end, the focal length is the focal length of the entire zoom lens system, FNO. Is the F number, ω is the half angle of view, fb is the back focus, f1, f2,... Are the focal lengths of the lens groups. The total length is obtained by adding back focus to the distance from the lens front surface to the lens final surface. The back focus represents the distance from the last lens surface to the paraxial image surface in terms of air.

Further, the aspherical shape is expressed by the following equation when the optical axis direction is z, the direction orthogonal to the optical axis is y, the conical coefficient is k, and the aspherical coefficients are A4, A6, A8, and A10. .
z = (y ² / r) / [1+ {1− (1 + k) (y / r) ² } ^1/2 ]
+ A4y ⁴ + A6y ⁶ + A8y ⁸ + A10y ¹⁰
In the aspheric coefficient, “e−n” (n is an integer) indicates “10 ⁻ⁿ ”. The symbols of these specification values are common to the numerical data of the examples described later.

Numerical example 1
Unit mm

Surface data Surface number rd nd νd
Object ∞ ∞
1 200.000 0.40 1.72903 54.04
2 * 3.273 1.18
3 ∞ 4.65 1.88300 40.80
4 ∞ 0.21
5 9.122 0.80 1.94595 17.98
6 14.157 Variable
7 (Aperture) ∞ -0.50
8 * 3.742 1.80 1.55332 71.68
9 * -16.985 0.32
10 10.438 1.27 1.49700 81.54
11 -5.421 0.40 1.91082 35.25
12 6.392 0.40
13 7.697 1.00 1.53367 55.82
14 * -5.586 variable
15 -19.471 1.00 1.53367 55.82
16 * -3.371 0.31
17 * -2.859 0.40 1.53367 55.82
18 7.386 Variable
19 * 9.352 0.83 1.63493 23.90
20 * -20.773 0.30
21 ∞ 0.30 1.51633 64.14
22 ∞ 0.70
Image plane ∞

Aspheric data 2nd surface
k = -0.274
A4 = -1.99537e-03, A6 = -2.58039e-05, A8 = -9.39645e-06
8th page
k = -2.228
A4 = 4.53625e-03, A6 = -8.13280e-05, A8 = 6.82728e-06
9th page
k = 4.423
A4 = 1.67943e-03, A6 = -7.88648e-05, A8 = -2.62814e-06
14th page
k = -4.001
A4 = 1.10666e-03, A6 = 1.80226e-04, A8 = 7.82646e-05
16th page
k = 0.000
A4 = 4.61411e-03, A6 = -1.41368e-04, A8 = -1.27075e-04
17th page
k = 0.000
A4 = 7.23481e-03, A6 = -3.46512e-04, A8 = -1.21948e-04
19th page
k = 0.000
A4 = -1.53947e-03, A6 = -2.06800e-05
20th page
k = 0.000
A4 = 5.00000e-04, A6 = -4.88652e-05

Zoom data
WE ST TE
Focal length 3.40 5.75 9.69
FNO. 2.40 3.44 4.65
Angle of view 2ω 69.28 42.20 25.47
fb (in air) 1.22 1.19 1.20
Total length (in air) 25.80 25.77 25.78

d6 7.11 4.11 0.76
d14 1.71 1.00 1.90
d18 1.30 5.01 7.46

Each group focal length
f1 = -6.59 f2 = 6.04 f3 = -8.33 f4 = 10.27

Numerical example 2
Unit mm

Surface data Surface number rd nd νd
Object ∞ ∞
1 200.000 0.40 1.73007 51.70
2 * 3.207 1.17
3 ∞ 4.65 1.88300 40.80
4 ∞ 0.22
5 9.212 0.80 1.94595 17.98
6 14.649 Variable
7 (Aperture) ∞ -0.50
8 * 3.398 1.85 1.55337 70.47
9 * -13.211 0.10
10 14.756 1.53 1.49737 81.45
11 -9.224 0.40 1.91070 34.62
12 3.150 0.22
13 * 3.356 1.06 1.53367 55.82
14 * -5.762 variable
15 -12.426 0.79 1.53367 55.82
16 * -4.493 0.43
17 * -3.051 0.40 1.53367 55.82
18 23.740 Variable
19 * 10.346 0.84 1.63493 23.90
20 * -14.948 0.30
21 ∞ 0.30 1.51633 64.14
22 ∞ 0.70
Image plane ∞

Aspheric data 2nd surface
k = -0.179
A4 = -2.62914e-03, A6 = -4.45919e-05, A8 = -1.63156e-05
8th page
k = -2.205
A4 = 4.87045e-03, A6 = -1.82169e-04
9th page
k = -3.559
A4 = 6.08844e-04, A6 = -1.12952e-04
13th page
k = 0.000
A4 = -4.24897e-03, A6 = -3.38158e-04
14th page
k = -5.000
A4 = -2.77515e-03, A6 = 1.10596e-04
16th page
k = 0.000
A4 = -7.19754e-03, A6 = -9.93372e-04
17th page
k = 0.000
A4 = -7.64145e-03, A6 = -9.48260e-04
19th page
k = 0.000
A4 = -1.18464e-03, A6 = 4.52097e-05
20th page
k = 0.000
A4 = 5.00000e-04, A6 = 1.00000e-04

Zoom data
WE ST TE
Focal length 3.45 5.81 9.82
FNO. 2.45 3.51 4.77
Angle of view 2ω 68.41 41.83 25.15
fb (in air) 1.20 1.17 1.20
Total length (in air) 25.60 25.57 25.59

d6 7.11 4.10 0.78
d14 1.64 1.01 2.03
d18 1.30 4.94 7.23

Each group focal length
f1 = -6.51 f2 = 5.96 f3 = -8.53 f4 = 9.76

Numerical Example 3
Unit mm

Surface data Surface number rd nd νd
Object ∞ ∞
1 200.000 0.40 1.72903 54.04
2 * 3.324 1.15
3 ∞ 4.70 1.88300 40.80
4 ∞ 0.19
5 8.808 0.80 1.94595 17.98
6 12.906 Variable
7 (Aperture) ∞ -0.50
8 * 4.399 1.43 1.62263 58.16
9 * -36.406 0.50
10 4.806 1.08 1.49700 81.54
11 26.975 0.40 2.00100 29.13
12 3.363 0.28
13 * 5.478 1.23 1.53367 55.82
14 * -8.143 variable
15 -68.013 0.95 1.53367 55.82
16 * -3.530 0.18
17 * -3.143 0.40 1.53367 55.82
18 7.849 Variable
19 * 8.435 1.15 1.63493 23.90
20 * -28.648 0.30
21 ∞ 0.30 1.51633 64.14
22 ∞ 0.70
Image plane ∞

Aspheric data 2nd surface
k = -0.357
A4 = -1.59618e-03, A6 = -1.37159e-06, A8 = -6.27652e-06
8th page
k = -2.072
A4 = 1.33346e-03, A6 = -4.70405e-05, A8 = -1.49100e-05, A10 = -8.27073e-08
9th page
k = -2.838
A4 = -7.25052e-04, A6 = -4.80920e-06, A8 = -1.63979e-05, A10 = 9.31676e-08
13th page
k = 0.000
A4 = -1.91909e-03, A6 = 2.09010e-04
14th page
k = -0.152
A4 = 1.25388e-04, A6 = 1.66254e-04
16th page
k = 0.000
A4 = 4.34496e-03, A6 = -9.93946e-04
17th page
k = 0.000
A4 = 5.26957e-03, A6 = -1.00616e-03
19th page
k = 0.000
A4 = -1.31603e-03, A6 = 1.00000e-04
20th page
k = 0.000
A4 = 5.00000e-04, A6 = 1.00000e-04

Zoom data
WE ST TE
Focal length 3.41 5.75 9.71
FNO. 2.41 3.41 4.61
Angle of view 2ω 69.79 42.34 25.43
fb (in air) 1.22 1.17 1.18
Total length (in air) 25.92 25.87 25.88

d6 7.22 4.09 0.75
d14 1.84 1.00 2.50
d18 1.30 5.27 7.11

Each group focal length
f1 = -6.50 f2 = 6.15 f3 = -11.23 f4 = 10.39

Numerical Example 4
Unit mm

Surface data Surface number rd nd νd
Object ∞ ∞
1 200.000 0.40 1.72903 54.04
2 * 3.375 1.22
3 ∞ 4.70 1.88300 40.80
4 ∞ 0.18
5 8.400 0.80 1.94595 17.98
6 11.572 Variable
7 (Aperture) ∞ -0.50
8 * 4.397 1.39 1.62263 58.16
9 * -31.947 0.50
10 4.473 1.01 1.49700 81.54
11 29.847 0.40 2.00100 29.13
12 3.310 0.29
13 * 5.543 1.17 1.53367 55.82
14 * -8.711 variable
15 58.308 1.16 1.53367 55.82
16 * 4.332 0.16
17 * 4.986 0.54 1.63493 23.90
18 6.609 Variable
19 * 8.950 0.90 1.53367 55.82
20 * -14.641 0.30
21 ∞ 0.30 1.51633 64.14
22 ∞ 0.70
Image plane ∞

Aspheric data 2nd surface
k = -0.432
A4 = -1.16535e-03, A6 = 3.93914e-05, A8 = -5.88806e-06
8th page
k = -1.875
A4 = 1.60384e-03, A6 = -6.53111e-06, A8 = -1.65869e-05, A10 = 1.25589e-06
9th page
k = 4.366
A4 = 1.95308e-04, A6 = -3.13082e-05, A8 = -1.26102e-05, A10 = 1.20565e-06
13th page
k = 0.000
A4 = -5.37169e-04, A6 = 2.51737e-05
14th page
k = -5.000
A4 = -4.01184e-05, A6 = 1.19704e-04
16th page
k = 0.000
A4 = 8.99287e-03, A6 = -1.28030e-03
17th page
k = 0.000
A4 = 6.93301e-03, A6 = -9.33535e-04
19th page
k = 0.000
A4 = -2.91744e-03, A6 = 1.00000e-04
20th page
k = 0.000
A4 = 9.08723e-05, A6 = -1.68958e-05

Zoom data
WE ST TE
Focal length 3.41 5.73 9.71
FNO. 2.42 3.41 4.60
Angle of view 2ω 69.88 42.50 25.42
fb (in air) 1.23 1.17 1.19
Total length (in air) 25.91 25.85 25.87

d6 7.21 4.09 0.75
d14 1.86 0.92 2.50
d18 1.27 5.33 7.09

Each group focal length
f1 = -6.41 f2 = 6.10 f3 = -12.34 f4 = 10.55

Numerical Example 5
Unit mm

Surface data Surface number rd nd νd
Object ∞ ∞
1 200.000 0.40 1.72271 55.03
2 * 3.178 1.23
3 ∞ 4.70 1.88300 40.80
4 ∞ 0.20
5 8.682 0.80 1.94595 17.98
6 12.664 Variable
7 (Aperture) ∞ -0.50
8 * 4.298 1.52 1.62851 59.17
9 * -23.894 0.50
10 4.358 1.06 1.49739 81.45
11 20.224 0.40 2.00130 26.74
12 3.074 0.30
13 * 5.260 1.25 1.53367 55.82
14 * -11.101 Variable
15 306.869 0.40 1.53367 55.82
16 * 3.817 0.21
17 * 4.974 0.78 1.63493 23.90
18 9.063 Variable
19 * 11.027 0.90 1.53367 55.82
20 * -14.936 0.30
21 ∞ 0.30 1.51633 64.14
22 ∞ 0.70
Image plane ∞

Aspheric data 2nd surface
k = -0.511
A4 = -1.22056e-03, A6 = 5.50708e-05, A8 = -8.77194e-06
8th page
k = -1.873
A4 = 1.62197e-03, A6 = 4.50251e-07, A8 = -1.60647e-05, A10 = 1.64748e-06
9th page
k = -5.000
A4 = 2.86438e-04, A6 = -1.87756e-05, A8 = -1.15812e-05, A10 = 1.57748e-06
13th page
k = 0.000
A4 = 5.61945e-04, A6 = 2.88440e-04
14th page
k = -5.000
A4 = 1.37995e-03, A6 = 4.52102e-04
16th page
k = 0.000
A4 = 8.47460e-03, A6 = -1.14980e-03
17th page
k = 0.000
A4 = 6.65787e-03, A6 = -7.04108e-04
19th page
k = 0.000
A4 = -4.18702e-03, A6 = 1.00000e-04
20th page
k = 0.000
A4 = -3.00000e-03, A6 = 4.99570e-05

Zoom data
WE ST TE
Focal length 3.42 5.71 9.73
FNO. 2.49 3.50 4.76
Angle of view 2ω 69.61 43.19 25.84
fb (in air) 1.21 1.16 1.18
Total length (in air) 25.71 25.65 25.68

d6 7.21 4.09 0.75
d14 1.86 0.93 2.50
d18 1.27 5.32 7.10

Each group focal length
f1 = -6.25 f2 = 5.99 f3 = -12.66 f4 = 12.03

Numerical Example 6
Unit mm

Surface data Surface number rd nd νd
Object ∞ ∞
1 * -293.426 0.40 1.74320 49.29
2 * 3.527 1.23
3 ∞ 4.70 1.88300 40.80
4 ∞ 0.19
5 8.850 0.80 1.94595 17.98
6 12.934 Variable
7 (Aperture) ∞ -0.50
8 * 3.942 1.46 1.49710 81.56
9 * -33.818 0.50
10 3.756 0.93 1.49700 81.54
11 6.927 0.40 2.00100 29.13
12 2.959 0.37
13 * 5.936 1.28 1.53367 55.82
14 * -12.536 variable
15 * -16.239 0.78 1.53367 55.82
16 * -3.786 0.32
17 * -3.172 0.40 1.53367 55.82
18 * 20.485 variable
19 * 8.440 0.90 1.53367 55.82
20 * -24.546 0.30
21 ∞ 0.30 1.51633 64.14
22 ∞ 0.70
Image plane ∞

Aspheric data first surface
k = 0.000
A4 = 8.00933e-04, A6 = -2.55067e-05
Second side
k = -0.352
A4 = -4.77492e-04, A6 = 5.75994e-05, A8 = -1.10487e-05
8th page
k = -2.270
A4 = 2.92448e-03, A6 = -2.02194e-04, A8 = 2.17785e-05, A10 = -1.32814e-06
9th page
k = 5.000
A4 = 2.68550e-04, A6 = -1.27727e-04, A8 = 2.38530e-05, A10 = -1.78412e-06
13th page
k = 0.000
A4 = 6.36307e-04, A6 = 4.47535e-04
14th page
k = -1.519
A4 = 2.04355e-03, A6 = 4.78766e-04
15th page
k = 0.000
A4 = 1.61081e-03, A6 = 3.75675e-04
16th page
k = 0.000
A4 = 4.68874e-03, A6 = 6.83603e-04
17th page
k = 0.000
A4 = 5.92913e-03, A6 = 9.28635e-04
18th page
k = 0.000
A4 = 1.24836e-03, A6 = 2.11112e-04, A8 = 2.84280e-05
19th page
k = 0.000
A4 = -1.72135e-04, A6 = -1.00000e-04, A8 = 5.71199e-05
20th page
k = 0.000
A4 = -1.40792e-04, A6 = 1.00000e-04, A8 = 6.54713e-05

Zoom data
WE ST TE
Focal length 3.43 5.78 9.78
FNO. 2.43 3.45 4.66
Angle of view 2ω 69.61 42.89 25.72
fb (in air) 1.21 1.18 1.19
Total length (in air) 25.91 25.88 25.89

d6 7.29 4.16 0.75
d14 2.05 0.90 2.29
d18 1.19 5.47 7.49

Each group focal length
f1 = -6.58 f2 = 6.21 f3 = -12.41 f4 = 11.88

Numerical Example 7
Unit mm

Surface data Surface number rd nd νd
Object ∞ ∞
1 * -149.587 0.40 1.74320 49.29
2 * 3.518 1.23
3 ∞ 4.70 1.91082 35.25
4 ∞ 0.50
5 9.528 1.10 1.94595 17.98
6 14.619 Variable
7 (Aperture) ∞ -0.30
8 * 4.199 1.47 1.49710 81.56
9 * -18.863 0.29
10 3.792 0.75 1.49700 81.54
11 5.339 0.40 1.84666 23.78
12 3.019 0.83
13 * 72.066 0.73 1.51633 64.06
14 * -7.065 variable
15 * -17.039 0.82 1.53071 55.69
16 * -4.356 0.28
17 * -4.131 0.40 1.53071 55.69
18 * 12.080 variable
19 * 15.748 1.04 1.53071 55.69
20 * -8.596 0.40
21 ∞ 0.30 1.51633 64.14
22 ∞ 0.70
Image plane ∞

Aspheric data first surface
k = 0.000
A4 = 7.27861e-04, A6 = -2.63700e-05
Second side
k = -0.195
A4 = -1.18954e-03, A6 = 6.42509e-05, A8 = -1.77626e-05
8th page
k = -5.000
A4 = 6.48812e-03, A6 = -4.82578e-04, A8 = 2.00255e-06, A10 = 2.42127e-06
9th page
k = -4.166
A4 = 3.28280e-04, A6 = 2.34135e-04, A8 = -8.13475e-05, A10 = 7.76079e-06
13th page
k = 0.000
A4 = 1.56489e-03, A6 = 6.93389e-04
14th page
k = -5.000
A4 = 7.84780e-04, A6 = 8.29918e-04
15th page
k = 0.000
A4 = -1.36831e-03, A6 = 1.03344e-03
16th page
k = 0.000
A4 = 1.25828e-03, A6 = 9.96955e-04
17th page
k = 0.000
A4 = 2.49605e-03, A6 = -1.45660e-06
18th page
k = 0.000
A4 = 5.31750e-04, A6 = -3.33403e-04, A8 = 8.25086e-05
19th page
k = 0.000
A4 = -1.04881e-03, A6 = -4.63631e-05, A8 = 3.84133e-05
20th page
k = 0.000
A4 = 5.00000e-04, A6 = 1.00000e-04, A8 = 3.04143e-05

Zoom data
WE ST TE
Focal length 3.35 5.66 9.55
FNO. 2.46 3.48 4.76
Angle of view 2ω 70.85 43.63 26.31
fb (in air) 1.31 1.26 1.30
Total length (in air) 27.11 27.06 27.10

d6 7.52 4.14 0.55
d14 2.14 0.98 2.18
d18 1.50 6.04 8.43

Each group focal length
f1 = -6.60 f2 = 6.39 f3 = -12.75 f4 = 10.64

Next, the values of conditional expressions (1) to (10) in each example will be listed.
Conditional Example Example 1 Example 2 Example 3
(1) φ _1o / φ _2o 1.44 1.42 1.45
(2) n _3p -n _3n 0.00 0.00 0.00
(3) Δ _2G / φ _1o 2.10 2.12 2.11
(4) (r _3oi -r _3io ) / (r _3oi + r _3io ) 0.08 0.19 0.06
(5) n _ave 1.60 1.60 1.62
(6) Δ _3G / Δ _2G 0.97 0.94 0.90
(7) f _1i / f _1o -5.51 -5.48 -5.77
(8) f ₁ / (f _w × f _t ) ^1/2 -1.15 -1.12 -1.13
(9) f ₂ / (f _w × f _t ) ^1/2 1.05 1.02 1.07
(10) (Fno _w × Fno _t ) ^1/2 / (f _w × f _t ) ^1/2 0.58 0.59 0.58

Conditional Example Example 4 Example 5 Example 6 Example 7
(1) φ _1o / φ _2o 1.46 1.44 1.47 1.47
(2) n _3p -n _3n 0.10 0.10 0.00 0.00
(3) Δ _2G / φ _1o 2.10 2.13 2.12 2.26
(4) (r _3oi -r _3io ) / (r _3oi + r _3io ) -0.07 -0.13 0.09 0.03
(5) n _ave 1.62 1.62 1.59 1.56
(6) Δ _3G / Δ _2G 0.90 0.90 0.96 0.99
(7) f _1i / f _1o -6.12 -5.95 -5.77 -5.67
(8) f ₁ / (f _w × f _t ) ^1/2 -1.11 -1.08 -1.14 -1.17
(9) f ₂ / (f _w × f _t ) ^1/2 1.06 1.04 1.07 1.13
(10) (Fno _w × Fno _t ) ^1/2 / (f _w × f _t ) ^1/2 0.58 0.60 0.58 0.61

(Information processing device)
Now, the zoom lens of the present invention as described above or an imaging device using the zoom lens can be mounted on an information processing apparatus such as a portable electronic device. Examples of such information processing apparatuses include, but are not limited to, digital cameras, PCs, and mobile phones as portable electronic devices. The information processing apparatus of the present invention is not limited to a portable electronic device.

  FIG. 23 shows a block diagram of such an information processing apparatus. The information processing apparatus 500 includes an input unit 501, a processing unit 502, an imaging device 503, an image processing unit 504, and a display unit 505. Further, as illustrated, the information processing apparatus preferably further includes a communication unit 506, a voice acquisition unit 507, an information recording unit 508, and the like.

  The input unit 501 operates the information processing apparatus 500. The processing unit 502 processes at least information from the input unit 501. The imaging device 503 acquires image information based on information from the processing unit 502. An image processing unit 504 processes image information acquired by the imaging device 503. A display unit 505 displays the processed image. Here, the imaging device 503 is equipped with the zoom lens of the present invention.

  Furthermore, the communication unit 506 is configured to be able to transmit (communicate) image information acquired by the imaging device 503. The sound acquisition unit 507 acquires sound information, and the information recording unit 509 records the acquired image information and sound information.

(Digital camera)
FIGS. 16 to 18 are conceptual diagrams of a configuration in which the zoom lens according to the present invention is incorporated in a photographing optical system 141 of a digital camera which is an information processing apparatus. 16 is a front perspective view showing the appearance of the digital camera 140, FIG. 17 is a rear perspective view thereof, and FIG. 18 is a cross-sectional view showing the configuration of the digital camera 140.

  In this example, the digital camera 140 includes a photographing optical system 141 having a photographing optical path 142, a finder optical system 143 having a finder optical path 144, a shutter button 145, a flash 146, a liquid crystal display monitor 147, and the like. When the shutter button 145 disposed at the upper part is pressed, photographing is performed through the photographing optical system 141, for example, the zoom lens of the first embodiment, in conjunction therewith. An object image formed by the photographing optical system 141 is formed on the imaging surface of the CCD 149 through the cover glass C, a near infrared cut filter, and an optical low-pass filter (not shown).

  The object image received by the CCD 149 is displayed as an electronic image on a liquid crystal display monitor 147 provided on the back of the camera via the processing means 151. Further, the processing means 151 is connected to a recording means 152 so that a photographed electronic image can be recorded. The recording unit 152 may be provided separately from the processing unit 151, or may be configured to perform recording / writing electronically using a flexible disk, a memory card, an MO, or the like. Further, instead of the CCD 149, a silver salt camera in which a silver salt film is arranged may be configured.

  In the digital camera 140, the shutter button 145 corresponds to the input unit 501 of the information processing device 500, the imaging optical system 141 and the CCD 149 correspond to the imaging device 503, the processing unit 151 corresponds to the image processing unit 504, and the liquid crystal display. A monitor 147 corresponds to the display unit 505. A CPU that controls the entire digital camera 140 corresponds to the processing unit 502. Further, the recording unit 152 corresponds to the information recording unit 508.

  Further, a finder objective optical system 153 is disposed on the finder optical path 144. The object image formed by the finder objective optical system 153 is formed on the field frame 157 of the Porro prism 155 that is an image erecting member. Behind this polyprism 155, an eyepiece optical system 159 for guiding an erect image to the observer eyeball E is disposed. Cover members 150 are disposed on the incident side of the photographing optical system 141 and the finder objective optical system 153 and on the exit side of the eyepiece optical system 159, respectively.

  Since the digital camera 140 configured in this manner is a zoom lens having a large aperture and a high optical performance, the photographing optical system 141 can realize an inexpensive digital camera with high performance and a very thin depth direction.

  In addition, in the example of FIG. 18, although a parallel plane board is arrange | positioned as the cover member 150, you may omit.

(computer)
Next, a personal computer which is an example of an information processing apparatus in which the zoom lens of the present invention is incorporated as an objective optical system is shown in FIGS. 19 is a front perspective view of the personal computer 300 with the cover open, FIG. 20 is a sectional view of the photographing optical system 303 of the personal computer 300, and FIG. 21 is a side view of FIG. As shown in FIGS. 19 to 21, the personal computer 300 includes a keyboard 301, information processing means and recording means, a monitor 302, and a photographing optical system 303.

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

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

  A cover glass 102 for protecting the objective optical system 100 is disposed at the tip of the mirror frame. The object image received by the electronic image sensor chip 162 is input to the processing means of the personal computer 300 via the terminal 166. Finally, the object image is displayed on the monitor 302 as an electronic image. FIG. 19 shows an image 305 taken by the operator as an example. The image 305 can also be displayed on a communication partner's personal computer from a remote location via the processing means. The Internet and telephone are used for image transmission to remote places.

  In the personal computer 300, the keyboard 301 corresponds to the input unit 501 of the information processing apparatus 500, the imaging optical system 303 including the objective optical system 100 and the electronic imaging chip 162 corresponds to the imaging apparatus 503, and the monitor 302 corresponds to the display unit 505. Correspond. A built-in CPU corresponds to the processing unit 502 and the image processing unit 504.

(mobile phone)
Next, FIG. 22 shows a telephone which is an example of an information processing apparatus in which the zoom lens of the present invention is incorporated as a photographing optical system, particularly a mobile telephone which is convenient to carry. 22A is a front view of the mobile phone 400, FIG. 22B is a side view, and FIG. 22C is a cross-sectional view of the photographing optical system 405. As shown in FIGS. 22A to 22C, the mobile phone 400 includes a microphone unit 401 that inputs an operator's voice as information, a speaker unit 402 that outputs a voice of a call partner, and an operator who receives information. A push button 403 for inputting information, a monitor 404 for displaying information such as a photographed image and a telephone number of the operator and the other party, a photographing optical system 405, an antenna 406 for transmitting and receiving communication radio waves, and an image And processing means (CPU 408 in FIG. 24) for processing information, communication information, input signals, and the like. Here, the monitor 404 is a liquid crystal display element. In the drawing, the arrangement positions of the respective components are not particularly limited to these.

  The photographing optical system 405 includes an objective lens 212 including a zoom lens (abbreviated in the drawing) according to the present invention disposed on a photographing optical path 407, and an image sensor chip 162 that receives an object image. These are built in the mobile phone 400. A cover glass C is disposed between the objective lens 212 and the electronic image sensor chip 162.

  Here, an optical low-pass filter (not shown) is additionally attached on the image pickup device chip 162 to be integrally formed as the image pickup unit 160 and is fitted into the rear end of the lens frame 213 of the objective lens 212 with one touch. Therefore, the centering of the objective lens 212 and the image sensor chip 162 and the adjustment of the surface interval are unnecessary, and the assembling is simplified. Further, a cover glass 214 for protecting the objective lens 212 is disposed at the tip (not shown) of the lens frame 213. The zoom lens driving mechanism in the lens frame 213 is not shown.

  The object image received by the imaging element chip 162 is input to the processing means via the terminal, and is displayed as an electronic image on the monitor 404, the monitor of the communication partner, or both. Further, when transmitting an image to a communication partner, the processing means includes a signal processing function for converting information of an object image received by the image sensor chip 162 into a signal that can be transmitted. Note that the imaging element chip 162 may have not only a function of receiving object light and converting it into image data, but also a function of performing simple image processing using the image data.

  In the mobile phone 400, the push button 403 corresponds to the input unit 501 of the information processing apparatus 500, the imaging optical system 405 and the imaging unit 160 correspond to the imaging apparatus 503, the imaging element chip 162 corresponds to the image processing unit 504, The monitor 404 corresponds to the display unit 505, the antenna 406 corresponds to the communication unit 506, and the microphone unit 401 corresponds to the sound acquisition unit 507. A CPU 408 that controls the mobile phone 400 corresponds to the processing unit 502, and a built-in memory 409 corresponds to the information recording unit 508. FIG. 24 shows a block diagram of the mobile phone 400.

  As described above, the zoom lens according to the present invention and the imaging apparatus using the zoom lens are useful in that the optical system has a large aperture while having high imaging performance and being small and thin.

G1 ... first lens group G2 ... second lens group G3 ... third lens group G4 ... fourth lens group S ... aperture stop C ... cover glass I ... image surface Lo ... object side lens Li of the third lens group ... first Lens La on the image side of the three lens groups ... Air lens 100 of the third lens group ... Objective optical system 102 ... Cover glass 140 ... Digital camera 141 ... Shooting optical system 142 ... Shooting optical path 143 ... Finder optical system 144 ... Finder path optical path 145 ... Shutter button 146 ... Flash 147 ... Liquid crystal display monitor 149 ... CCD
150: cover member 151 ... processing means 152 ... recording means 153 ... finder objective optical system 155 ... erecting prism 157 ... field frame 159 ... eyepiece optical system 160 ... imaging unit 162 ... imaging element chip 166 ... terminal 212 ... objective lens 213 Mirror frame 214 ... Cover glass 300 ... PC 301 ... Keyboard 302 ... Monitor 303 ... Shooting optical system 304 ... Shooting optical path 305 ... Image 400 ... Mobile phone 401 ... Microphone unit 402 ... Speaker unit 403 ... Push button 404 ... Monitor 405 ... Shooting Optical system 406 ... antenna 407 ... photographing optical path 408 ... CPU
409 ... Memory 500 ... Information processing device 501 ... Input unit 502 ... Processing unit 503 ... Imaging device 504 ... Image processing unit 505 ... Display unit 506 ... Communication unit 507 ... Audio acquisition unit 508 ... Information recording unit

Claims (18)

From the object side,
A first lens group having negative refractive power;
A second lens group having a positive refractive power;
A third lens group having negative refractive power;
A fourth lens group having a positive refractive power,
When zooming, the first lens group is fixed, the second lens group is moved, the third lens group is moved, and the fourth lens group is fixed,
The first lens group includes, in order from the object side, a negative lens, a reflective optical element, and a positive lens.
The second lens group includes, in order from the object side, a stop, a positive lens, a cemented lens having negative refractive power, and a positive lens.
The zoom lens, wherein the cemented lens includes a positive lens and a negative lens. The zoom lens according to claim 1, wherein the following conditional expression (1) is satisfied.
1.1 ≦ φ _1o / φ _2o ≦ 1.8 (1)
here,
φ _1o is half the effective aperture of the lens surface closest to the object side of the first lens group,
φ _2o is half the effective aperture of the lens surface closest to the object side of the second lens group,
It is. The zoom lens according to claim 1, wherein the third lens group includes a positive lens and a negative lens, and satisfies the following conditional expression (2).
0 ≦ n _3p −n _3n ≦ 0.20 (2)
here,
n _3p is the refractive index at the d-line of the positive lens of the third lens group,
n _3n is the refractive index at the d-line of the negative lens of the third lens group,
It is. The zoom lens according to any one of claims 1 to 3, wherein the following conditional expression (3) is satisfied.
1.8 ≦ Δ _2G / φ _1o ≦ 2.6 (3)
here,
Δ _2G is the amount of movement of the second lens group when moving from the wide-angle end to the telephoto end,
φ _1o is half the effective aperture of the lens surface closest to the object side of the first lens group,
It is. 5. The zoom lens according to claim 1, wherein the third lens group includes an object-side lens and an image-side lens, and satisfies the following conditional expression (4): 6. .
−0.4 ≦ (r _3oi −r _3io ) / (r _3oi + r _3io ) ≦ 0.4 (4)
here,
r _3oi is the paraxial radius of curvature of the image side surface of the lens on the object side of the third lens group,
r _3io is the paraxial radius of curvature of the object side surface of the image side lens of the third lens group,
It is. The zoom lens according to claim 1, wherein the following conditional expression (5) is satisfied.
n _ave ≦ 1.75 (5)
here,
n _ave is an average value of refractive indexes obtained from all the lenses located on the image side of the first lens group,
It is. The zoom lens according to claim 1, wherein the following conditional expression (6) is satisfied.
0.7 ≦ Δ _3G / Δ _2G ≦ 1.2 (6)
here,
Δ _2G is the amount of movement of the second lens group when moving from the wide-angle end to the telephoto end,
Δ _3G is the amount of movement of the third lens group when moving from the wide-angle end to the telephoto end,
It is. The zoom lens according to claim 1, wherein the following conditional expression (7) is satisfied.
−10 ≦ f _1i / f _1o ≦ −2 (7)
here,
f _1o is the focal length of the lens on the object side of the first lens group,
f _1i is the focal length of the image-side lens of the first lens group,
It is. The zoom lens according to claim 1, wherein the following conditional expression (8) is satisfied.
−1.5 ≦ f ₁ / (f _w × f _t ) ^1/2 ≦ −0.7 (8)
here,
f ₁ is the focal length of the first lens group,
_fw is the focal length of the entire zoom lens system at the wide-angle end,
f _t is the focal length of the entire zoom lens system at the telephoto end,
It is. The zoom lens according to any one of claims 1 to 9, wherein the following conditional expression (9) is satisfied.
0.5 ≦ f ₂ / (f _w × f _t ) ^1/2 ≦ 1.5 (9)
here,
f ₂ is the focal length of the second lens group,
_fw is the focal length of the entire zoom lens system at the wide-angle end,
f _t is the focal length of the entire zoom lens system at the telephoto end,
It is. The zoom lens according to any one of claims 1 to 9, wherein the following conditional expression (10) is satisfied.
_{0.53 ≦ (Fno w × Fno t} ) 1/2 / (f w × f t) 1/2 ≦ 0.65 (10)
here,
Fno _w is, F-number of the zoom lens at the wide angle end,
Fno _t is, F-number of the zoom lens at the telephoto end,
_fw is the focal length of the entire zoom lens system at the wide-angle end,
f _t is the focal length of the entire zoom lens system at the telephoto end,
It is.   The zoom lens according to any one of claims 1 to 11, wherein the fourth lens group includes one resin lens.   The zoom lens according to any one of claims 1 to 12, wherein a diameter of the diaphragm is constant during zooming. The zoom lens according to any one of claims 1 to 13,
An imaging device comprising an imaging device having an imaging surface. An input unit for operating the information processing apparatus;
At least a processing unit for processing information from the input unit;
An imaging device that acquires image information based on information from the processing unit;
An image processing unit for processing image information acquired by the imaging apparatus;
A display unit for displaying the processed image,
15. The information processing apparatus according to claim 14, wherein the imaging apparatus is the imaging apparatus according to claim 14. With a communication unit,
The information processing apparatus according to claim 15, wherein the image information acquired by the imaging apparatus can be transmitted (communication).   The information processing apparatus according to claim 15, further comprising an audio acquisition unit and an information recording unit.   The information processing apparatus according to claim 15, wherein the information processing apparatus is a portable electronic device.

Images