JP4906439B2 - Zoom lens and electronic imaging apparatus using the same - Google Patents

Description

  The present invention relates to a zoom lens. The present invention also relates to an electronic imaging apparatus using the same. In particular, the present invention relates to an electronic imaging device such as a video camera or a digital camera that has been downsized.

  In recent years, digital cameras that shoot subjects using electronic image pickup devices such as CCDs and CMOSs instead of silver salt film cameras have become mainstream. Furthermore, it has come to have a number of categories in a wide range from high-functional types for business use to compact popular types. Users of popular digital cameras have a desire to enjoy shooting in various scenes anytime and anywhere. For this reason, a digital camera of a small size, in particular, a type in which the size in the thickness direction is thin, which can be easily carried in a pocket of a clothes or a bag, is easy to carry.

  On the other hand, a zoom ratio of a compact type digital camera is generally about 3 times, but a camera with a higher zoom ratio than the conventional one is required. As a zoom lens that can maintain a relatively high zoom ratio, the first lens unit having positive refractive power, the second lens group having negative refractive power, the third lens group having positive refractive power, and the fourth lens having positive refractive power are arranged from the object side. A type of zoom lens having a lens group is known.

  On the other hand, among the camera sizes, the size in the thickness direction is mainly determined by the size of the lens barrel, so it is effective to make the lens barrel thinner in order to achieve a thinner camera. .

  Recently, a so-called collapsible lens barrel is generally used in which the lens barrel protrudes from the camera body and is housed in the camera body when being carried. Therefore, there is a need for a zoom lens that takes into account the reduction in thickness of the lens barrel when retracted. In the following prior art, the second lens group is composed of two lenses, a negative lens and a positive lens, so that the thickness direction of the second lens group is reduced.

JP 2004-258240 A JP 2004-199000 A JP 2001-133687 A JP 11-119100 A

  However, the above-described conventional techniques have the following problems. The zoom lens described in Example 4 of Japanese Patent Application Laid-Open No. 2004-258240 has a total of five lenses in the first lens group and the second lens group in the first lens group. In this case, if the angle of view on the wide angle side is to be ensured, the diameter of the lens closest to the object side in the first lens group cannot be reduced, which is disadvantageous for downsizing the lens barrel in the radial direction. Moreover, even if the retracting method is adopted, it is disadvantageous for reducing the thickness in the optical axis direction.

  In the zoom lens described in Japanese Patent Laid-Open No. 2004-199000, the total number of lenses in the first lens group and the second lens group is three, Japanese Patent Laid-Open Nos. 11-119100 and 2001-133687. Describes a zoom lens in which the total number of lenses in the first lens group and the second lens group is four. However, it is difficult to suppress the influence of fluctuations in aberrations in the first and second lens groups. Is not tripled.

  The present invention has been made in view of such problems, and its object is to provide a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refraction. An object of the present invention is to provide a zoom lens having a powerful fourth lens group, which can be reduced in size and easily ensured aberration performance by devising the first lens group and the second lens group.

It is another object of the present invention to provide an electronic imaging device that is easy to miniaturize by including such a zoom lens.
It is another object of the present invention to provide a zoom lens and an electronic image pickup apparatus that can be easily reduced in size, secured aberration performance, and secured a zoom ratio by devising each lens group of the zoom lens.

  In order to solve the above problems, a first zoom lens of the present invention includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a positive refractive power. And a fourth lens group having positive refracting power, and when changing magnification from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group, the second lens group and the third lens The first lens group is composed of two lenses, a positive lens and a negative lens, and the second lens group is a negative lens in order from the object side. These lenses are composed of two positive lenses, and satisfy the following conditional expressions (1) and (2).

1.78 <n _d2n <2.10 (1)
35.0 <ν _d2n <50.0 (2)
However,
n _d2n is the refractive index of the negative lens in the second lens group with respect to the d-line,
ν _d2n is the Abbe number of the negative lens in the second lens group,
It is.

Hereinafter, to explain why the effect of taking the above-described structure in the first zoom lens. In the present invention, in order from the object side, there are a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power. A configuration is adopted in which zooming is performed by changing the interval.

  By adopting such a configuration, it is possible to efficiently share the zooming burden for each group, and while preventing aberration fluctuations during zooming from being reduced, the zoom lens prevents an increase in the amount of movement of each group. Leads to a more compact design.

  By configuring the second lens group in order from the object side, the negative lens and the positive lens, the thickness direction of the group can be reduced and the size in the outer diameter direction can also be reduced. The first lens group is composed of two lenses, a positive lens and a negative lens, and the second lens group is composed of two lenses, a negative lens and a positive lens in order from the object side. Thereby, the thickness direction of the group can be reduced, and the size in the outer diameter direction can be reduced.

  In the first lens group and the second lens group, the incident height of off-axis rays from the optical axis tends to be high, so that when the necessary amount of lens edge is secured, the axial thickness tends to increase. There is. In addition, as the number of lenses in the first lens group and the second lens group increases, the height of off-axis rays passing through these lens groups becomes higher, and the on-axis thickness for securing the edge is required to be thicker. Become. Naturally, the axial thickness increases as the number of lenses in the first lens group and the second lens group increases.

  From this point of view, the first lens group and the second lens group are each composed of a small number of two lenses, thereby reducing the size in the radial direction and the thickness on the optical axis of these lens groups, and the collapsed state. This is advantageous for downsizing the lens barrel.

  Further, the first lens group is constituted by one positive lens and one negative lens, which is advantageous for correcting chromatic aberration with a small number of lenses. As a result, even if the change in the distance between the first lens group and the second lens group is increased to ensure a zoom ratio, deterioration of chromatic aberration can be easily suppressed.

  Further, the second lens group in which the thickness direction of the lens group is particularly large in the related art is configured by two lenses of a negative lens and a positive lens in order from the object side. In many cases, the second lens group has a large negative power because it is a lens group that tends to have a large variable load.

  If the second lens group is composed of only two lenses, a negative lens and a positive lens, the single negative lens in the second lens group bears a large negative power. On the other hand, in order to ensure high optical performance in the entire zoom range, it is effective to suppress the occurrence of aberrations in this group as small as possible. Therefore, in order to suppress the aberration generated in the negative lens to be small, conditional expressions (1) and (2) are satisfied for the negative lens of the second lens group. This defines the refractive index and the Abbe number for the d-line of the negative lens of the second lens group.

  Conditional expression (1) is a conditional expression relating to the balance between cost and aberration correction function. By making it not exceed the upper limit of conditional expression (1), it becomes easy to suppress the cost of the material to be used and the manufacturing cost. If the upper limit is exceeded, the material used becomes expensive and difficult to process.

  By ensuring that the lower limit of conditional expression (1) is not exceeded, it is easy to ensure negative refractive power even if the curvature of the lens surface is reduced. As a result, it is possible to suppress the barrel distortion at the wide-angle end from becoming too large, reduce coma due to the negative lens itself, etc., the occurrence of coma at the wide-angle end and the telephoto end, and the aberration during zooming It becomes easier to suppress fluctuations.

Conditional expression (2) is a conditional expression related to chromatic aberration correction, in particular, off-axis magnification chromatic aberration correction.
It is preferable not to exceed the upper limit, to ensure the refractive index of the material to be used and to facilitate aberration correction.

  Exceeding the upper limit of conditional expression (2) is advantageous in correcting chromatic aberration, but the refractive index tends to be small with existing lens materials.

  It is preferable not to fall below the lower limit of conditional expression (2) to reduce chromatic dispersion and to easily suppress chromatic aberration.

The following is more preferable.
1.79 <n _d2n <2.00 (1 ′)
37.0 <ν _d2n <45.0 (2 ′)
It is more preferable that the following is satisfied.
1.80 <n _d2n <1.95 (1 ″)
40.0 <ν _d2n <47.0 (2 ″)
Thereby, the above-described effects can be further achieved. Note that these conditional expressions may specify only the upper limit value or the lower limit value of a more limited conditional expression. The same applies to each numerical conditional expression described below.

In the present invention, a negative lens is disposed in each of the first lens group and the second lens group, thereby making it easy to suppress the occurrence of spherical aberration and the like due to the composition system of the first and second lens groups at the wide angle end. .
In addition, since the spherical aberration in the first lens group can be suppressed even when the second lens group is separated from the first lens group, it is easy to secure the respective powers of the first and second lens groups, and the distance between them. Even if the change is increased, it is easy to suppress the variation of the spherical aberration, which is advantageous for increasing the zoom ratio.

  Furthermore, in the first zoom lens, the focal length of the negative lens of the first lens group and the focal length of the negative lens of the second lens group are the following conditions (A) and (B): , (C) is preferably satisfied.

_{0.6 <| f 1n | / f} t <5.0 (A)
0.08 <| f _2n | / _ft <0.35 (B)
5.0 <| f _1n | / | f _2n | <25.0 (C)
However,
f _1n is the focal length of the negative lens in the first lens group,
f _2n is the focal length of the negative lens in the second lens group,
f _t is the focal length of the entire zoom lens system at the telephoto end,
It is.

  These conditional expressions (A), (B), and (C) are the effects of aberration correction by negative power while maintaining an appropriate balance for the power of the negative lens in the first lens group and the negative lens in the second lens group. It is a condition for ensuring.

  By making the focal length of the negative lens of the first lens group not exceed the upper limit of the conditional expression (A), it is advantageous for correcting lateral chromatic aberration and spherical aberration in the first lens group.

  By making it not fall below the lower limit of the conditional expression (A), it becomes easy to secure the power of the first lens group, and it becomes easy to secure the zooming function in the second lens group.

By making the focal length of the negative lens of the second lens group not to exceed the upper limit of the conditional expression (B), it becomes easy to secure the negative power of the second lens group, which is advantageous for downsizing and high zoom ratio. It becomes.
By making it not fall below the lower limit of conditional expression (B), it becomes easy to suppress the occurrence of various aberrations in the second lens group.

  By making sure that the upper limit of conditional expression (C) is not exceeded, it becomes easy to suppress variations in chromatic aberration and spherical aberration during zooming.

  By making sure that the lower limit of conditional expression (C) is not exceeded, it becomes easy to reduce the change amount of the variable interval with respect to the zoom amount.

  If these conditions (A), (B), and (C) are satisfied at the same time, it is advantageous to perform aberration, downsizing, and high zoom ratio.

For each conditional expression, the following is more preferable.
_{0.8 <| f 1n | / f} t <4.0 (A ')
0.10 <| f _2n | / _ft <0.30 (B ′)
6.0 <| f _1n | / | f _2n | <21.0 (C ′)
It is more preferable that the following is satisfied.
_{1.0 <| f 1n | / f} t <3.0 (A '')
0.12 <| f _2n | / _ft <0.25 (B ″)
7.0 <| f _1n | / | f _2n | <18.0 (C ″)
As a result, the above-described effects can be further achieved.

  In the third zoom lens, in the first to second zoom lenses, it is preferable that the two lenses in the first lens group satisfy the following conditional expression.

1.4 <| f _1n | / f _1p <4.5 (D)
However,
f _1p is the focal length of the positive lens in the first lens group,
f _1n is the focal length of the negative lens in the first lens group,
It is.

  By securing the power of the negative lens so as not to exceed the upper limit of the conditional expression (D), it is advantageous for correcting chromatic aberration and the like generated in the positive lens.

  By making sure that the lower limit of conditional expression (D) is not exceeded, it is possible to prevent the power of the negative lens from becoming too strong and to ensure the positive power of the first lens group having the two-lens configuration. Moreover, it becomes easy to suppress the influence on the aberration due to the relative decentration of both lenses.

The following is more preferable.
1.6 <| f _1n | / f _1p <4.0 (D ′)
It is more preferable that the following is satisfied.
1.8 <| f _1n | / f _1p <3.5 (D ″)
As a result, the above-described effects can be further achieved.

  In order to obtain a good optical performance efficiently while realizing a compact size, it is more preferable to add various ideas in addition to the above in the present invention. Details will be described below.

  In the first zoom lens to the fourth zoom lens, in order to more effectively correct the aberration in the second lens group, a positive lens in the second lens group is replaced with a meniscus convex toward the object side. It is preferable to use a shape to suppress the incident angle of the off-axis light beam. At this time, it is preferable that the shape of the positive lens of the second lens group satisfies the following conditional expression (3).

−5.0 <SF _2p <−1.0 (3)
However,
SF _2p = (R _2pf + R _2pr ) / (R _2pf −R _2pr )
R _2pf is the paraxial radius of curvature of the object side surface of the positive lens in the second lens group,
R _2pr is the paraxial radius of curvature of the image side surface of the positive lens in the second lens group,
It is.

  The reason and action of the fourth zoom lens having the above configuration will be described. By ensuring the curvature of the object side surface of this lens so as not to exceed the upper limit of conditional expression (3), it is advantageous for correcting astigmatism at the wide-angle end and spherical aberration at the telephoto end.

  By avoiding falling below the lower limit of conditional expression (3) and suppressing the curvature of the lens surface from becoming too large, it is easy to suppress the occurrence of off-axis high-order aberrations. Specifically, it is preferable for reducing off-axis field curvature and lateral chromatic aberration.

The following is more preferable.
−3.8 <SF _2p <−1.4 (3 ′)
It is more preferable that the following is satisfied.
−2.6 <SF _2p <−1.8 (3 ″)
Thereby, the above-described effects can be further achieved.

  In the first to fourth zoom lenses, it is preferable that the fifth zoom lens satisfies the following conditional expression (4) for the power of the second lens group.

0.12 <| f ₂ / f _t | <0.60 (4)
However,
f ₂ is the focal length of the second lens group,
f _t is the focal length of the entire zoom lens system at the telephoto end,
It is.

  The reason and effect | action which took the said structure in the 5th zoom lens are demonstrated. By ensuring that the upper limit of conditional expression (4) is not exceeded, the power of the second lens group is secured, and it becomes easier to obtain a zoom ratio with respect to the amount of change in the distance between the first and second lens groups, and the lens barrel becomes compact. Is advantageous.

  It is preferable to suppress the aberration by suppressing the power of the second lens group so as not to fall below the lower limit of the conditional expression (4).

The following is more preferable.
0.18 <| f ₂ / f _t | <0.49 (4 ′)
It is more preferable that the following is satisfied.
0.24 <| f ₂ / f _t | <0.38 (4 ″)
Thereby, the above-described effects can be further achieved.

The sixth zoom lens is a positive lens of the second lens group so that aberration correction can be performed sufficiently even when the second lens group is composed of two lenses in the first to fifth zoom lenses. It is preferable that conditional expressions (5) and (6) are satisfied.
1.88 <n _d2p <2.20 (5)
13.0 <ν _d2p <30.0 (6)
However,
n _d2p is the refractive index of the positive lens in the second lens group with respect to the d-line,
ν _d2p is the Abbe number of the positive lens in the second lens group,
It is.

In a sixth zoom lens now explained taking the above construction. Conditional expressions (5) and (6) define the refractive index and the Abbe number for the d-line of the positive lens in the second lens group.

  In many cases, the second lens group has a large negative power because it is a lens group that tends to have a large variable load. Therefore, in order to correct the aberration due to the negative lens of the second lens group with one positive lens, it is effective to set the refractive index and dispersion of this lens appropriately.

  Conditional expression (5) is a conditional expression related to the correction and cost of curvature of field and coma. By making it not exceed the upper limit of conditional expression (5), it becomes easy to suppress the cost and manufacturing cost of the material used. If the upper limit is exceeded, the material used becomes expensive and difficult to process.

  By making sure that the lower limit of conditional expression (5) is not exceeded, it is easy to ensure the refractive power even if the curvature of the lens surface is reduced. As a result, curvature of field at the wide-angle end can be suppressed, coma and the like due to the positive lens itself can be reduced, and coma and the like at the wide-angle end and the telephoto end can be easily suppressed, and aberration variation at the time of zooming can be easily suppressed.

  Conditional expression (6) is a conditional expression related to chromatic aberration correction, in particular, off-axis chromatic aberration correction. In order to satisfactorily correct chromatic aberration generated by the negative lens of the second lens group within this group, it is preferable that the positive lens has an appropriate dispersion.

  By avoiding exceeding the upper limit of conditional expression (6), it is preferable to ensure dispersion of the positive lens and cancel chromatic aberration generated by the negative lens in the second lens group, thereby reducing color blur in the captured image.

  By avoiding falling below the lower limit of conditional expression (6), it is preferable to suppress the dispersion on the short wavelength side from being excessively large, and to reduce color bleeding due to the secondary spectrum.

Each conditional expression is more preferably as follows.
1.90 <n _d2p <2.16 (5 ′)
15.0 <ν _d2p <25.0 (6 ′)

More preferably, it is as follows.
1.92 <n _d2p <2.11 (5 ″)
17.0 <ν _d2p <21.0 (6 ″)
As a result, the above-described effects can be further achieved.

  In the present invention, the second lens group is composed of only a negative lens and a positive lens, but the negative lens of the second lens group bears a large negative power. In order to ensure high optical performance in the entire zoom range, it is preferable to suppress the aberration generated in the negative lens as small as possible.

  Therefore, it is preferable that the seventh zoom lens has a large power as a biconcave lens in the first to sixth zoom lenses. Furthermore, it is preferable that the shape satisfies the following conditional expression (7).

0.35 <SF _2n <1.00 (7)
However,
SF _2n = (R _2nf + R _2nr ) / (R _2nf −R _2nr )
R _2nf is the paraxial radius of curvature of the object side surface of the negative lens in the second lens group,
R _2nr is the paraxial radius of curvature of the image side surface of the negative lens in the second lens group,
It is.

  The reason and effect | action which took the said structure in the 7th zoom lens are demonstrated. By suppressing the curvature of the image side surface of the negative lens so as not to exceed the upper limit of conditional expression (7), it becomes easy to suppress the occurrence of curvature of field at the wide angle end. Moreover, it becomes easy to suppress the thickness of the second lens group on the axis. Further, it is easy to suppress the thickness of the second lens group in the optical axis direction and to secure the angle of view.

  By suppressing the negative curvature of the object side surface of the negative lens so as not to fall below the lower limit of conditional expression (7), it becomes easy to suppress various off-axis aberrations at the wide angle end.

The following is more preferable.
0.45 <SF _2n <0.85 (7 ′)
It is more preferable that the following is satisfied.
0.55 <SF _2n <0.70 (7 ″)
Thereby, the above-described effects can be further exhibited.

  In order to suppress the occurrence of aberrations and obtain good optical performance, it is preferable to arrange an aspherical surface on at least one lens surface of the negative lens of the second lens group. Further, both the object side surface and the image side surface of the negative lens may be aspherical.

  In those cases, it is preferable that the eighth zoom lens satisfies the following conditional expression (8) in the first to seventh zoom lenses.

0.030 <(| asp _2nf | + | asp _2nr |) / f _w <0.320 (8)
However,
asp _2nf is the amount of aspherical deviation on the object-side lens surface of the negative lens in the second lens group,
asp _2nr is the amount of aspherical deviation on the image side lens surface of the negative lens in the second lens group,
f _w is the focal length of the entire zoom lens system at the wide-angle end,
It is.

  The amount of aspherical deviation is the maximum incidence of light at the wide-angle end of the lens surface when a spherical surface having the same apex as the apex of the lens surface and having a paraxial radius of curvature of the lens surface as the reference radius is used as the reference spherical surface. The distance from the reference spherical surface to the lens surface when measured in a direction parallel to the optical axis at a high position. When the image side direction is a positive sign and the lens surface is spherical or flat, the aspherical deviation amount is zero.

  The reason and action of the above configuration in the eighth zoom lens will be described. By avoiding exceeding the upper limit of the conditional expression (8) and preventing the sum of the absolute values of the aspherical deviations from becoming too large, the eccentricity between the surfaces of the aspherical lens due to manufacturing errors occurs. It becomes easy to suppress deterioration of optical performance.

  It is preferable not to fall below the lower limit of conditional expression (8) so as to ensure the sum of absolute values of the aspherical deviation amount and to ensure the aberration correction effect by the aspherical surface.

The following is more preferable.
0.040 <(| asp _2nf | + | asp _2nr |) / f _w <0.250 (8 ′)
It is more preferable that the following is satisfied.
0.050 <(| asp _2nf | + | asp _2nr |) / f _w <0.180 (8 ″)
Thereby, the above-described effects can be further achieved.

  Further, in the ninth zoom lens, in the eighth zoom lens, it is preferable that an aspheric surface of the negative lens in the second lens group is an aspheric surface whose refractive power increases as the distance from the optical axis increases.

  The reason and action of the ninth zoom lens having the above configuration will be described. In addition, that refractive power becomes large means that negative refractive power becomes small or positive refractive power becomes large. With this configuration, distortion and coma at the wide-angle end can be easily suppressed.

  Further, the tenth zoom lens is the ninth zoom lens, and the negative lens in the second lens group is a biconcave lens. The refractive power increases as the object side surface and the image side surface of the biconcave lens both move away from the optical axis. It is preferable to use an aspherical surface with a large.

  The reason and operation of the tenth zoom lens will be described. This is advantageous for both reducing the thickness of the second lens group on the axis or in the peripheral portion and reducing the various aberrations of the second lens group.

  The eleventh zoom lens has a configuration in which, in the first to tenth zoom lenses, the first lens group includes two lenses of a negative lens and a positive lens in order from the object side.

  By disposing the negative lens and the positive lens in this order from the object side, it becomes easy to suppress variations in various aberrations due to zooming while providing a function for correcting chromatic aberration.

  In the twelfth zoom lens, the negative lens and the positive lens of the first lens group may be cemented with each other in the eleventh zoom lens. When a cemented lens is used, it is possible to effectively perform axial chromatic aberration correction that tends to be a problem when the telephoto end is made long-focused by increasing the zoom ratio.

  In addition, it is possible to suppress the deterioration of the optical performance due to the relative eccentricity of the lens due to the assembly error, which contributes to the improvement of the yield and the cost reduction.

  Further, the thirteenth zoom lens may be configured by an independent single lens in which the negative lens and the positive lens of the first lens group are not cemented with each other in the eleventh zoom lens.

  In this way, there are four refracting surfaces in the first lens group, the degree of freedom in design is increased, and distortion at the wide-angle end and coma at the telephoto end can be corrected more effectively. It becomes.

  In the fourteenth zoom lens, in the thirteenth zoom lens, it is preferable that a distance between the negative lens and the positive lens in the first lens group satisfies the following conditional expression (9).

0.0 ≦ L _1np / L ₁ <0.20 (9)
However,
L _1np is the axial distance between the negative lens and the positive lens in the first lens group,
L ₁ is the total thickness on the axis of the first lens group,
It is.

  The reason and action of the above configuration in the fourteenth zoom lens will be described. By making sure that the upper limit of conditional expression (9) is not exceeded, the height of the off-axis light beam that passes through the lens closest to the object side is suppressed, the effective diameter of this lens is reduced, and the radial direction of the entire zoom lens is reduced. This is advantageous for downsizing. Also, it is practically impossible to exceed the lower limit of conditional expression (9).

The following is more preferable.
0.0 ≦ L _1np / L ₁ <0.15 (9 ′)
It is more preferable that the following is satisfied.
0.0 ≦ L _1np / L ₁ <0.10 (9 ″)
Thereby, the above-described effects can be further achieved.

  In the fifteenth zoom lens, in the first to fourteenth zoom lenses, it is preferable that the configuration of the third lens group includes three or less lenses in order to reduce the thickness of the lens barrel.

  The sixteenth zoom lens may be configured such that, in the fifteenth zoom lens, the third lens group is composed of two lenses, a positive lens and a negative lens, in this order from the object side.

  By configuring with the minimum number of lenses for correcting various aberrations such as chromatic aberration occurring in the third lens group, the lens barrel can be made thinner. In addition, with such a lens arrangement, the front principal point can be positioned closer to the object, making it easy to ensure a zoom ratio and to reduce the amount of group movement. It will be advantageous.

  The seventeenth zoom lens has a configuration in which the third lens group is composed of a positive lens, a positive lens, and a negative lens in order from the object side in order to ensure higher optical performance in the fifteenth zoom lens. It is good.

By adopting such a lens arrangement, the positive power of the third lens group can be shared mainly by the two positive lenses, which is advantageous for correcting spherical aberration and coma.
Furthermore, it is preferable that the negative lens of the third lens group is cemented with an adjacent positive lens on the object side.

  The eighteenth zoom lens can correct axial chromatic aberration more effectively by joining the positive lens and the negative lens in the seventeenth zoom lens.

  Also, by dispersing the power of the positive lens between the two lenses and using the positive lens and the negative lens as a cemented lens, it is possible to prevent deterioration in optical performance due to the relative decentration of the lenses in the assembly process. Lead to improvement and cost reduction.

  In addition, the arrangement of one or more aspheric surfaces in the third lens group is effective in correcting spherical aberration and coma.

  Furthermore, it is more preferable that the positive lens closest to the object side in the third lens group is a double-sided aspheric surface.

  If an aspherical surface is placed on multiple lenses, the optical performance deterioration due to the relative decentration of the lens tends to be large, but by making both sides of one lens aspherical in this way, the optical performance deterioration due to the lens relative decentration can be kept small. However, it is possible to correct spherical aberration and coma aberration better.

  In particular, when the third lens group is configured by two lenses, it is possible to secure a degree of freedom in design, which is preferable in terms of both miniaturization and ensuring of optical performance.

  In the nineteenth zoom lens, it is preferable that the first lens group satisfies the following conditional expression (10) in terms of a balance between compactness and optical performance in the first to eighteenth zoom lenses.

_{0.50 <f 1 / f t <} 2.00 ··· (10)
However,
f ₁ is the focal length of the first lens group,
f _t is the focal length of the entire zoom lens system at the telephoto end,
It is.

  The reason and action of the nineteenth zoom lens will be described. By ensuring the power of the first lens group so as not to exceed the upper limit of conditional expression (10), it is easy to suppress the overall length of the entire zoom lens system, which is advantageous for downsizing the lens barrel.

  By making sure that the lower limit of conditional expression (10) is not exceeded, the power of the first lens group is suppressed, the occurrence of spherical aberration and coma at the telephoto end is suppressed, and good optical performance is easily secured.

The following is more preferable.
_{0.75 <f 1 / f t <} 1.80 ··· (10 ')
It is more preferable that the following is satisfied.
_{0.95 <f 1 / f t <} 1.60 ··· (10 '')
Thereby, the above-described effects can be further achieved.

  In the twentieth zoom lens, it is preferable that the power of the third lens group satisfies the following conditional expression (11) in the first to nineteenth zoom lenses.

_{0.16 <f 3 / f t <} 0.80 ··· (11)
However,
f ₃ is the focal length of the third lens group,
f _t is the focal length of the entire zoom lens system at the telephoto end,
It is.

  The reason and action of the twentieth zoom lens having the above configuration will be described. From the viewpoint of miniaturization, it is preferable to ensure that the power of the third lens group is secured so as not to exceed the upper limit of conditional expression (11), and to ensure a variable magnification burden in the third lens group.

  It is preferable that the power of the third lens group is moderately suppressed so as not to fall below the lower limit of conditional expression (11), and the occurrence of aberrations in the third lens group is suppressed.

The following is more preferable.
0.23 <f ₃ / _ft <0.60 (11 ′)
It is more preferable that the following is satisfied.
0.30 <f ₃ / _ft <0.40 (11 ″)
Thereby, the above-described effects can be further achieved.

  In the twenty-first zoom lens, the power of the fourth lens group in the first to twentieth zoom lenses satisfies the following conditional expression (12) in terms of ensuring telecentricity and correcting field curvature. It is preferable to do so.

_{0.24 <f 4 / f t <} 0.80 ··· (12)
However,
f ₄ is the focal length of the fourth lens group,
f _t is the focal length of the entire zoom lens system at the telephoto end,
It is.

The reason and action of the above configuration in the twenty-first zoom lens will be described. By ensuring the power of the fourth lens group so as not to exceed the upper limit of conditional expression (12), it is possible to secure telecentricity toward the image side and suppress overcorrection of field curvature.
Insufficient correction of curvature of field can be suppressed by appropriately suppressing the power of the fourth lens group so as not to fall below the lower limit of conditional expression (12).

The following is more preferable.
_{0.36 <f 4 / f t <} 0.70 ··· (12 ')
It is more preferable that the following is satisfied.
_{0.48 <f 4 / f t <} 0.62 ··· (12 '')
As a result, the above-described effects can be further achieved.

  The fourth lens group may be formed of a plastic material. The main role of the fourth lens group is to arrange the exit pupil position at an appropriate position so that light is efficiently incident on an electronic image sensor such as a CCD or CMOS. For such a role, if the power is set within the range of the conditional expression (12), a relatively large power is not required, and a material having a low refractive index such as a plastic lens is used. It is also possible to configure.

  If a plastic lens is used for the fourth lens group, the cost can be reduced and a cheaper zoom lens can be provided.

  Further, in order to achieve a high zoom ratio while maintaining the performance, it is more effective to efficiently give a zooming action to each lens group and to correct aberrations well over the entire zoom range.

  Therefore, in the 22nd zoom lens, in the 1st to 21st zoom lenses, at the time of zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group is widened, The first lens group, the second lens group, the third lens group, and the fourth lens group move so that the distance between the third lens group is narrowed and the distance between the third lens group and the fourth lens group is widened, Further, it is more preferable that the zoom lens has an aperture stop that moves in the optical axis direction together with the third lens group upon zooming.

  The reason and action of the twenty-second zoom lens will be described. By moving each lens group in this manner, it becomes possible to effectively give a zooming action to each lens group, and it is advantageous to achieve high performance even when the zoom ratio is increased.

  In addition, by moving the aperture stop together with the third lens group, it is possible to effectively correct the lateral chromatic aberration and distortion, and not only can be effective in terms of performance, but also the entrance pupil position and exit pupil position can be adjusted appropriately. It becomes possible to control.

  That is, the light beam height of the off-axis light beam at the wide-angle end and the light beam height of the off-axis light beam at the telephoto end can be balanced, and the outer diameter of the first lens group and the outer diameter of the fourth lens group are balanced and compact. It becomes possible to do. In particular, reducing the outer diameter of the first lens group at the wide-angle end effectively leads to a compact size in the lens thickness direction. In addition, since it becomes possible to control the fluctuation of the exit pupil position at the time of zooming, the incident angle of the light beam incident on the image pickup device (for example, CCD, CMOS, etc.) is kept within an appropriate range and the screen It is possible to prevent occurrence of brightness shading at corners, which is suitable for an electronic imaging apparatus.

Furthermore, in order to improve the overall length, aberration balance, and the like, the following configuration may be employed.
In the twenty-third zoom lens, in the twenty-second zoom lens, in zooming from the wide-angle end to the telephoto end, the first lens group is preferably moved so that it is closer to the object side at the telephoto end than at the wide-angle end. At that time, it may be moved only to the object side, or may be moved along a locus convex toward the image side.
Further, the second lens group may be moved only to the image side, or may be moved along a locus convex toward the image side.

The third lens group is preferably moved only to the object side.
Further, the fourth lens group may be moved only to the object side, or may be moved only to the image side. Alternatively, it may be moved along a locus convex toward the object side or convex toward the image side.
The aperture stop and the shutter unit are preferably arranged between the second lens group and the third lens group, and moved together with the third lens group during zooming.

  The entrance pupil can be positioned close to the object side, and the exit pupil can be easily moved away from the image plane. In addition, since the off-axis light beam height is low, the shutter unit does not need to be enlarged, and the dead space when moving the aperture stop and the shutter unit can be reduced.

  In addition, the 24th zoom lens is preferably the 1st to 23rd zoom lens, and the zoom lens of each of the above inventions is preferably a four-group zoom lens.

  Limiting the number of lens groups to four is preferable for downsizing.

  The 25th zoom lens preferably satisfies the following conditional expression (13) in the 1st to 24th zoom lenses.

3.8 < _ft / _fw <10.0 ... (13)
However,
f _w is the focal length of the entire zoom lens at the wide-angle end,
f _t is the focal length of the entire zoom lens at the telephoto end,
It is.

  The reason and action of the above configuration in the 25th zoom lens will be described. By avoiding exceeding the upper limit of conditional expression (13), it is easy to suppress the amount of movement of the lens group, and it is easy to suppress the total length.

  By making sure that the lower limit of conditional expression (13) is not exceeded, it is possible to perform shooting while changing the shooting angle of view while taking advantage of the size and cost of the present invention.

The following is more preferable.
4.3 <f _t / f _w <7.0 (13 ′)
It is more preferable that the following is satisfied.
4.7 < _ft / _fw <5.0 (13 '')
Thereby, the above-described effects can be further achieved.

In addition, the zoom lens of each of the above-described inventions is easy to ensure telecentricity. Therefore, in the electronic imaging apparatus of the present invention, the above-described zoom lens and an electronic imaging element (CCD, CMOS, etc.) that converts an optical image formed by the zoom lens into an electrical signal may be disposed on the image side of the zoom lens. Is possible.
It is more preferable that a plurality of the above-mentioned inventions are arbitrarily satisfied at the same time.

As is apparent from the above description, the present invention is configured with the first lens group and the second lens group by devising the first lens group having a positive refractive power and the second lens group having a negative refractive power. Even if the number of lenses is small and compact, a zoom lens that can easily maintain optical performance can be provided.
In addition, by providing such a zoom lens, it is possible to provide an electronic imaging device that can be easily miniaturized.

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

  Examples 1 to 9 of the zoom lens according to the present invention will be described below. FIGS. 1 to 9 show lens cross sections of the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on an object point at infinity in Examples 1 to 9, respectively. 1 to 9, the first lens group is G1, the second lens group is G2, the aperture stop is S, the third lens group is G3, the fourth lens group is G4, and a wavelength region limiting coat that limits infrared light. The parallel flat plate constituting the low-pass filter subjected to is indicated by F, the parallel flat plate of the cover glass of the electronic image sensor is indicated by C, and the image plane is indicated by I. In addition, you may give the multilayer film for a wavelength range restriction | limiting to the surface of the cover glass C. FIG. Further, the cover glass C may have a low-pass filter action.

  As shown in FIG. 1, the zoom lens of Example 1 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, an aperture stop S, A third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power are disposed.

  During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the image side, the third lens group G3 moves to the object side, and the fourth lens The group G4 once moves to the object side, then moves in the reverse direction and moves to the image side.

  In order from the object side, the first lens group G1 includes a first negative meniscus lens having a convex surface directed toward the object side and a second biconvex positive lens. The second lens group G2 includes a third biconcave negative lens and a fourth positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 includes a fifth biconvex positive lens and a sixth negative meniscus lens having a convex surface directed toward the object side. The fourth lens group G4 is composed of a seventh biconvex positive lens.

  The aspherical surfaces are used on five surfaces including both surfaces of the third biconcave negative lens, both surfaces of the fifth biconvex positive lens, and the object side surface of the seventh biconvex positive lens.

  As shown in FIG. 2, the zoom lens according to the second embodiment includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, an aperture stop S, A third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power are disposed.

  At the time of zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 once moves to the image side, and then the moving direction reverses and moves to the object side. The lens group G3 moves to the object side, and the fourth lens group G4 once moves to the object side, and then the moving direction is reversed and moves to the image side.

  In order from the object side, the first lens group G1 includes a first negative meniscus lens having a convex surface directed toward the object side and a second biconvex positive lens. The first negative meniscus lens and the second biconvex positive lens are cemented. The second lens group G2 includes a third biconcave negative lens and a fourth positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 includes a fifth biconvex positive lens, a sixth biconvex positive lens, and a seventh biconcave negative lens. The sixth biconvex positive lens and the seventh biconcave negative lens are cemented. The fourth lens group G4 is composed of an eighth biconvex positive lens.

  The aspherical surfaces are used for five surfaces including both surfaces of the third biconcave negative lens, both surfaces of the fifth biconvex positive lens, and the object side surface of the eighth biconvex positive lens.

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

  During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the image side, the third lens group G3 moves to the object side, and the fourth lens Group G4 moves to the object side.

  In order from the object side, the first lens group G1 includes a first negative meniscus lens having a convex surface directed toward the object side and a second biconvex positive lens. The second lens group G2 includes a third biconcave negative lens and a fourth positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 includes a fifth biconvex positive lens, a sixth biconvex positive lens, and a seventh biconcave negative lens. The sixth biconvex positive lens and the seventh biconcave negative lens are cemented. The fourth lens group G4 is composed of an eighth biconvex positive lens.

  The aspherical surfaces are used for five surfaces including both surfaces of the third biconcave negative lens, both surfaces of the fifth biconvex positive lens, and the object side surface of the eighth biconvex positive lens.

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

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the image side, then moves to the object side, and the third lens group G3 moves to the object side. The fourth lens group G4 once moves to the object side and then moves to the image side.

  In order from the object side, the first lens group G1 includes a first negative meniscus lens having a convex surface directed toward the object side and a second biconvex positive lens. The second lens group G2 includes a third biconcave negative lens and a fourth positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 includes a fifth biconvex positive lens, a sixth biconvex positive lens, and a seventh biconcave negative lens. The sixth biconvex positive lens and the seventh biconcave negative lens are cemented. The fourth lens group G4 is composed of an eighth biconvex positive lens.

  The aspherical surfaces are used for five surfaces including both surfaces of the third biconcave negative lens, both surfaces of the fifth biconvex positive lens, and the object side surface of the eighth biconvex positive lens.

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

  During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the image side, the third lens group G3 moves to the object side, and the fourth lens The group G4 once moves to the object side and then moves to the image side.

  In order from the object side, the first lens group G1 includes a first negative meniscus lens having a convex surface directed toward the object side and a second biconvex positive lens. The second lens group G2 includes a third biconcave negative lens and a fourth positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 includes a fifth biconvex positive lens, a sixth positive meniscus lens having a convex surface directed toward the object side, and a seventh negative meniscus lens having a convex surface directed toward the object side. The sixth positive meniscus lens and the seventh negative meniscus lens are cemented. The fourth lens group G4 is composed of an eighth biconvex positive lens.

  The aspherical surface includes the image-side surface of the second biconvex positive lens, both surfaces of the third biconcave negative lens, both surfaces of the fifth biconvex positive lens, and the object side surface of the eighth biconvex positive lens. Used on six sides.

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

  During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the image side, the third lens group G3 moves to the object side, and the fourth lens The group G4 once moves to the object side and then moves to the image side.

  In order from the object side, the first lens group G1 includes a first negative meniscus lens having a convex surface directed toward the object side and a second biconvex positive lens. The second lens group G2 includes a third biconcave negative lens and a fourth positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 includes a fifth biconvex positive lens, a sixth positive meniscus lens having a convex surface directed toward the object side, and a seventh negative meniscus lens having a convex surface directed toward the object side. The sixth positive meniscus lens and the seventh negative meniscus lens are cemented. The fourth lens group G4 is composed of an eighth biconvex positive lens.

  The aspherical surface includes the image-side surface of the second biconvex positive lens, both surfaces of the third biconcave negative lens, both surfaces of the fifth biconvex positive lens, and the object side surface of the eighth biconvex positive lens. Used on six sides.

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

  During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the image side, the third lens group G3 moves to the object side, and the fourth lens The group G4 once moves to the object side and then moves to the image side.

  In order from the object side, the first lens group G1 includes a first negative meniscus lens having a convex surface directed toward the object side and a second biconvex positive lens. The second lens group G2 includes a third biconcave negative lens and a fourth positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 includes a fifth biconvex positive lens, a sixth positive meniscus lens having a convex surface directed toward the object side, and a seventh negative meniscus lens having a convex surface directed toward the object side. The sixth positive meniscus lens and the seventh negative meniscus lens are cemented. The fourth lens group G4 is composed of an eighth biconvex positive lens.

  The aspherical surface includes the image-side surface of the second biconvex positive lens, both surfaces of the third biconcave negative lens, both surfaces of the fifth biconvex positive lens, and the object side surface of the eighth biconvex positive lens. Used on six sides.

  As shown in FIG. 8, the zoom lens according to the eighth embodiment includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, an aperture stop S, A third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power are disposed.

  During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the image side, the third lens group G3 moves to the object side, and the fourth lens The group G4 once moves to the object side and then moves to the image side.

  In order from the object side, the first lens group G1 includes a first negative meniscus lens having a convex surface directed toward the object side and a second biconvex positive lens. The second lens group G2 includes a third biconcave negative lens and a fourth positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 includes a fifth biconvex positive lens, a sixth positive meniscus lens having a convex surface directed toward the object side, and a seventh negative meniscus lens having a convex surface directed toward the object side. The sixth positive meniscus lens and the seventh negative meniscus lens are cemented. The fourth lens group G4 is composed of an eighth biconvex positive lens.

  The aspherical surface includes the image-side surface of the second biconvex positive lens, both surfaces of the third biconcave negative lens, both surfaces of the fifth biconvex positive lens, and the object side surface of the eighth biconvex positive lens. Used on six sides.

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

  During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the object side, the second lens group G2 moves to the image side, the third lens group G3 moves to the object side, and the fourth lens The group G4 once moves to the object side and then moves to the image side.

  In order from the object side, the first lens group G1 includes a first negative meniscus lens having a convex surface directed toward the object side and a second biconvex positive lens. The second lens group G2 includes a third biconcave negative lens and a fourth positive meniscus lens having a convex surface directed toward the object side. The third lens group G3 includes a fifth biconvex positive lens, a sixth positive meniscus lens having a convex surface directed toward the object side, and a seventh negative meniscus lens having a convex surface directed toward the object side. The sixth positive meniscus lens and the seventh negative meniscus lens are cemented. The fourth lens group G4 is composed of an eighth biconvex positive lens.

  The aspherical surface includes the image-side surface of the second biconvex positive lens, both surfaces of the third biconcave negative lens, both surfaces of the fifth biconvex positive lens, and the object side surface of the eighth biconvex positive lens. Used on six sides.

Below, the numerical data of each said Example are shown. Symbols are the above, f is the focal length of the entire system, _FNO is the F number, ω is the half field angle, WE is the wide angle end, ST is the intermediate state, TE is the telephoto end, r ₁ , r ₂ . radius of curvature, d _1, d ₂ ... the spacing between the lens surfaces, n _d1, n _d2 ... d-line refractive index of each lens, ν _d1, ν _d2 ... is the Abbe number of each lens. The aspherical shape is represented by the following formula, where x is an optical axis with the light traveling direction being positive, and y is a direction orthogonal to the optical axis.

x = (y ² / r) / [1+ {1- (K + 1) (y / r) ² } ^1/2 ]
+ A ₄ y ⁴ + A ₆ y ⁶ + A ₈ y ⁸ + A ₁₀ y ¹⁰ + A ₁₂ y ¹²
Where r is the paraxial radius of curvature, K is the conic coefficient, and A ₄ , A ₆ , A ₈ , A ₁₀ , and A ₁₂ are the fourth, sixth, eighth, tenth, and twelfth aspheric coefficients, respectively. . In the aspheric coefficient, “e−n” (n is an integer) indicates “10 ⁻ⁿ ”.

Example 1

r ₁ = 21.447 d ₁ = 0.80 n _d1 = 1.92286 ν _d1 = 18.90
r ₂ = 16.568 d ₂ = 0.33
r ₃ = 19.065 d ₃ = 3.00 n _d2 = 1.72916 ν _d2 = 54.68
r ₄ = -635.214 d ₄ = (variable)
r ₅ = -27.371 (aspherical surface) d ₅ = 1.00 n _d3 = 1.88300 ν _d3 = 40.76
r ₆ = 5.547 (aspheric surface) d ₆ = 1.71
r ₇ = 10.368 d ₇ = 2.16 n _d4 = 1.92286 ν _d4 = 18.90
r ₈ = 32.087 d ₈ = (variable)
r ₉ = ∞ (aperture) d ₉ = 0.10
r ₁₀ = 4.015 (aspherical surface) d ₁₀ = 2.14 n _d5 = 1.58313 ν _d5 = 59.38
r ₁₁ = -20.737 (aspherical surface) d ₁₁ = 0.07
r ₁₂ = 6.067 d ₁₂ = 1.07 n _d6 = 1.92286 ν _d6 = 20.88
r ₁₃ = 3.042 d ₁₃ = (variable)
r ₁₄ = 13.673 (aspherical surface) d ₁₄ = 2.68 n _d7 = 1.52542 ν _d7 = 55.78
r ₁₅ = -65.892 d ₁₅ = (variable)
r ₁₆ = ∞ d ₁₆ = 0.50 n _d8 = 1.54771 ν _d8 = 62.84
r ₁₇ = ∞ d ₁₇ = 0.50
r ₁₈ = ∞ d ₁₈ = 0.50 n _d9 = 1.51633 ν _d9 = 64.14
r ₁₉ = ∞ d ₁₉ = 0.50
r ₂₀ = ∞ (imaging surface)

Aspheric coefficient Fifth surface R = -27.371
K = 0.065
A ₄ = 2.93685e-04
A ₆ = -1.29521e-05
A ₈ = 2.63539e-07
A ₁₀ = -7.77717e-10

6th surface R = 5.547
K = -0.216
A ₄ = -2.74527e-04
A ₆ = 5.81879e-06
A ₈ = -2.46028e-06
A ₁₀ = 7.68048e-08

Tenth face R = 4.015
K = -0.052
A ₄ = -1.29073e-03
A ₆ = -6.12402e-06
A ₈ = 1.86699e-06

11th surface R = -20.737
K = 0.000
A ₄ = 7.99142e-04
A ₆ = 6.56260e-05
A ₈ = 4.48582e-06

Face 14 R = 13.673
K = -0.880
A ₄ = 3.32538e-05
A ₆ = 3.03636e-05
A ₈ = -2.12591e-06
A ₁₀ = 6.32654e-08

Zoom data (∞)
WE ST TE
f (mm) 6.60 14.49 31.76
F _NO 4.47 5.71 5.99
2ω (°) 62.67 29.43 13.60
d ₄ 1.18 7.61 17.27
d ₈ 12.07 5.03 0.55
d ₁₃ 4.74 8.30 9.73
d ₁₅ 3.31 4.30 3.77

Example 2

r ₁ = 22.824 d ₁ = 0.80 n _d1 = 1.84666 ν _d1 = 23.78
r ₂ = 14.601 d ₂ = 2.82 n _d2 = 1.72916 ν _d2 = 54.68
r ₃ = 414.790 d ₃ = (variable)
r ₄ = -19.623 (aspherical surface) d ₄ = 0.90 n _d3 = 1.80495 ν _d3 = 40.90
r ₅ = 5.406 (aspheric surface) d ₅ = 1.71
r ₆ = 8.975 d ₆ = 2.07 n _d4 = 1.92286 ν _d4 = 18.90
r ₇ = 20.246 d ₇ = (variable)
r ₈ = ∞ (aperture) d ₈ = 0.10
r ₉ = 5.364 (aspherical surface) d ₉ = 2.57 n _d5 = 1.58313 ν _d5 = 59.38
r ₁₀ = -16.396 (aspherical surface) d ₁₀ = 0.10
r ₁₁ = 8.877 d ₁₁ = 2.16 n _d6 = 1.72916 ν _d6 = 54.68
r ₁₂ = -5.099 d ₁₂ = 0.40 n _d7 = 1.80100 ν _d7 = 34.97
r ₁₃ = 4.240 d ₁₃ = (variable)
r ₁₄ = 11.188 (aspherical surface) d ₁₄ = 2.14 n _d8 = 1.52542 ν _d8 = 55.78
r ₁₅ = -171.452 d ₁₅ = (variable)
r ₁₆ = ∞ d ₁₆ = 0.50 n _d9 = 1.54771 ν _d9 = 62.84
r ₁₇ = ∞ d ₁₇ = 0.50
r ₁₈ = ∞ d ₁₈ = 0.50 n _d10 = 1.51633 ν _d10 = 64.14
r ₁₉ = ∞ d ₁₉ = 0.50
r ₂₀ = ∞ (imaging surface)

Aspheric coefficient 4th surface R = -19.623
K = 0.089
A ₄ = 8.04207e-04
A ₆ = -2.03534e-05
A ₈ = 2.82387e-07
A ₁₀ = -1.69194e-09

5th surface R = 5.406
K = -0.329
A ₄ = 4.28184e-04
A ₆ = 2.10097e-05
A ₈ = -1.65174e-06
A ₁₀ = 1.28854e-08

9th surface R = 5.364
K = -0.166
A ₄ = -2.03573e-04
A ₆ = 4.18417e-05
A ₈ = 3.69979e-06

Tenth face R = -16.396
K = 0.000
A ₄ = 9.35195e-04
A ₆ = 6.75272e-05
A ₈ = 5.30410e-06

Face 14 R = 11.188
K = -1.490
A ₄ = 5.63156e-05
A ₆ = 1.24846e-05
A ₈ = -1.04700e-06
A ₁₀ = 3.12395e-08

Zoom data (∞)
WE ST TE
f (mm) 6.61 14.38 31.74
F _NO 3.60 4.46 6.02
2ω (°) 62.90 29.44 13.45
d ₃ 1.26 7.82 13.73
d ₇ 12.51 5.36 1.54
d ₁₃ 4.42 6.52 14.10
d ₁₅ 2.69 4.42 3.00

Example 3

r ₁ = 23.457 d ₁ = 0.80 n _d1 = 1.84666 ν _d1 = 23.78
r ₂ = 14.154 d ₂ = 0.40
r ₃ = 15.271 d ₃ = 3.00 n _d2 = 1.77250 ν _d2 = 49.60
r ₄ = -215.758 d ₄ = (variable)
r ₅ = -23.097 (aspherical surface) d ₅ = 1.00 n _d3 = 1.80495 ν _d3 = 40.90
r ₆ = 5.348 (aspherical surface) d ₆ = 1.40
r ₇ = 8.580 d ₇ = 2.00 n _d4 = 1.92286 ν _d4 = 18.90
r ₈ = 18.871 d ₈ = (variable)
r ₉ = ∞ (aperture) d ₉ = 0.10
r ₁₀ = 5.766 (aspherical surface) d ₁₀ = 2.45 n _d5 = 1.58313 ν _d5 = 59.38
r ₁₁ = -10.882 (aspherical surface) d ₁₁ = 0.10
r ₁₂ = 15.328 d ₁₂ = 1.44 n _d6 = 1.69680 ν _d6 = 55.53
r ₁₃ = -15.328 d ₁₃ = 1.22 n _d7 = 1.68893 ν _d7 = 31.07
r ₁₄ = 4.089 d ₁₄ = (variable)
r ₁₅ = 14.324 (aspheric surface) d ₁₅ = 2.60 n _d8 = 1.52542 ν _d8 = 55.78
r ₁₆ = -27.378 d ₁₆ = (variable)
r ₁₇ = ∞ d ₁₇ = 0.50 n _d9 = 1.54771 ν _d9 = 62.84
r ₁₈ = ∞ d ₁₈ = 0.50
r ₁₉ = ∞ d ₁₉ = 0.50 n _d10 = 1.51633 ν _d10 = 64.14
r ₂₀ = ∞ d ₂₀ = 0.45
r ₂₁ = ∞ (imaging surface)

Aspheric coefficient Fifth surface R = -23.097
K = 0.089
A ₄ = 1.80967e-04
A ₆ = -1.62280e-07
A ₈ = 3.96691e-08
A ₁₀ = -7.98836e-10

6th surface R = 5.348
K = -0.296
A ₄ = -1.84110e-04
A ₆ = 1.36361e-07
A ₈ = 1.68053e-07
A ₁₀ = -1.07186e-09

Tenth face R = 5.766
K = -1.073
A ₄ = -9.79726e-05
A ₆ = 1.50579e-06

11th surface R = -10.882
K = 7.693
A ₄ = 1.32858e-03
A ₆ = 3.01907e-05
A ₈ = 2.16650e-08
A ₁₀ = 6.54410e-11

15th surface R = 14.324
K = -0.001
A ₄ = 4.02883e-05
A ₆ = 5.91976e-06
A ₈ = -1.61602e-07
A ₁₀ = 2.12392e-09

Zoom data (∞)
WE ST TE
f (mm) 6.62 14.37 32.09
F _NO 3.83 5.11 6.00
2ω (°) 62.68 29.65 13.53
d ₄ 0.88 5.76 12.75
d ₈ 13.63 6.80 1.53
d ₁₄ 4.27 9.62 13.30
d ₁₆ 3.19 3.12 2.96

Example 4

r ₁ = 18.613 d ₁ = 0.83 n _d1 = 2.00170 ν _d1 = 20.64
r ₂ = 14.132 d ₂ = 0.32
r ₃ = 15.458 d ₃ = 3.00 n _d2 = 1.72916 ν _d2 = 54.68
r ₄ = -7762.115 d ₄ = (variable)
r ₅ = -19.900 (aspherical surface) d ₅ = 1.00 n _d3 = 1.80495 ν _d3 = 40.90
r ₆ = 4.735 (aspherical surface) d ₆ = 1.32
r ₇ = 7.926 d ₇ = 2.25 n _d4 = 2.00170 ν _d4 = 20.64
r ₈ = 18.204 d ₈ = (variable)
r ₉ = ∞ (aperture) d ₉ = 0.10
r ₁₀ = 5.243 (aspheric surface) d ₁₀ = 2.14 n _d5 = 1.58313 ν _d5 = 59.38
r ₁₁ = -14.423 (aspherical surface) d ₁₁ = 0.10
r ₁₂ = 13.297 d ₁₂ = 1.41 n _d6 = 1.69680 ν _d6 = 55.53
r ₁₃ = -13.297 d ₁₃ = 0.84 n _d7 = 1.68893 ν _d7 = 31.07
r ₁₄ = 4.302 d ₁₄ = (variable)
r ₁₅ = 12.620 (aspheric surface) d ₁₅ = 2.32 n _d8 = 1.52542 ν _d8 = 55.78
r ₁₆ = -41.640 d ₁₆ = (variable)
r ₁₇ = ∞ d ₁₇ = 0.50 n _d9 = 1.54771 ν _d9 = 62.84
r ₁₈ = ∞ d ₁₈ = 0.50
r ₁₉ = ∞ d ₁₉ = 0.50 n _d10 = 1.51633 ν _d10 = 64.14
r ₂₀ = ∞ d ₂₀ = 0.50
r ₂₁ = ∞ (imaging surface)


Aspheric coefficient Fifth surface R = -19.900
K = 0.089
A ₄ = 7.68359e-04
A ₆ = -2.74885e-05
A ₈ = 5.05160e-07
A ₁₀ = -3.51817e-09

6th surface R = 4.735
K = -0.296
A ₄ = 2.06227e-04
A ₆ = 1.05145e-05
A ₈ = -3.20724e-06
A ₁₀ = 5.51277e-08

Tenth face R = 5.243
K = -0.166
A ₄ = -3.57087e-04
A ₆ = 6.29255e-05
A ₈ = -2.02800e-07
A ₁₀ = 1.01728e-06

11th surface R = -14.423
K = 0.000
A ₄ = 1.07710e-03
A ₆ = 7.69622e-05
A ₈ = 3.07399e-06
A ₁₀ = 1.50112e-06

15th surface R = 12.620
K = -1.490
A ₄ = 5.63156e-05
A ₆ = 3.25061e-06
A ₈ = -1.24032e-07
A ₁₀ = 2.58656e-09

Zoom data (∞)
WE ST TE
f (mm) 6.62 14.41 31.64
F _NO 3.82 4.77 6.00
2ω (°) 62.97 29.10 13.54
d ₄ 1.12 7.18 12.54
d ₈ 12.66 6.25 1.55
d ₁₄ 5.19 8.85 14.31
d ₁₆ 3.01 3.57 3.17

Example 5

r ₁ = 84.159 d ₁ = 0.80 n _d1 = 2.00170 ν _d1 = 20.64
r ₂ = 34.486 d ₂ = 0.10
r ₃ = 22.651 d ₃ = 2.64 n _d2 = 1.76802 ν _d2 = 49.24
r ₄ = -68.862 (aspherical surface) d ₄ = (variable)
r ₅ = -22.850 (aspherical surface) d ₅ = 0.87 n _d3 = 1.88300 ν _d3 = 40.76
r ₆ = 5.672 (aspherical surface) d ₆ = 1.94
r ₇ = 11.112 d ₇ = 2.21 n _d4 = 1.94595 ν _d4 = 17.98
r ₈ = 35.757 d ₈ = (variable)
r ₉ = ∞ (aperture) d ₉ = 0.10
r ₁₀ = 4.712 (aspherical surface) d ₁₀ = 2.61 n _d5 = 1.58913 ν _d5 = 61.14
r ₁₁ = -14.330 (aspherical surface) d ₁₁ = 0.10
r ₁₂ = 7.122 d ₁₂ = 1.40 n _d6 = 1.73400 ν _d6 = 51.47
r ₁₃ = 38.362 d ₁₃ = 0.80 n _d7 = 2.00069 ν _d7 = 25.46
r ₁₄ = 3.667 d ₁₄ = (variable)
r ₁₅ = 14.436 (aspherical surface) d ₁₅ = 2.07 n _d8 = 1.74330 ν _d8 = 49.33
r ₁₆ = -91.806 d ₁₆ = (variable)
r ₁₇ = ∞ d ₁₇ = 0.40 n _d9 = 1.54771 ν _d9 = 62.84
r ₁₈ = ∞ d ₁₈ = 0.50
r ₁₉ = ∞ d ₁₉ = 0.50 n _d10 = 1.51633 ν _d10 = 64.14
r ₂₀ = ∞ d ₂₀ = 0.35
r ₂₁ = ∞ (imaging surface)

Aspheric coefficient 4th surface R = -68.862
K = 0.000
A ₄ = 1.40060e-05
A ₆ = 4.74804e-08
A ₈ = -1.12302e-09
A ₁₀ = 6.63012e-12

5th surface R = -22.850
K = 0.005
A ₄ = 4.03460e-04
A ₆ = -7.22829e-06
A ₈ = 6.48822e-08
A ₁₀ = -8.73779e-11

6th surface R = 5.672
K = -0.125
A ₄ = -1.79384e-04
A ₆ = 1.31075e-05
A ₈ = -1.16124e-06
A ₁₀ = 8.98567e-09

Tenth face R = 4.712
K = -0.084
A ₄ = -3.51732e-04
A ₆ = 2.84641e-05
A ₈ = 5.84562e-06
A ₁₀ = 4.88769e-07

11th surface R = -14.330
K = 0.000
A ₄ = 1.77733e-03
A ₆ = 5.54637e-05
A ₈ = 1.61880e-05
A ₁₀ = 5.93748e-07

15th surface R = 14.436
K = 0.000
A ₄ = -4.85530e-05
A ₆ = 2.21564e-05
A ₈ = -1.01006e-06
A ₁₀ = 1.88543e-08

Zoom data (∞)
WE ST TE
f (mm) 5.06 12.01 24.25
F _NO 3.39 4.97 5.05
2ω (°) 79.96 35.52 17.47
d ₄ 0.65 4.60 15.76
d ₈ 12.81 4.53 1.33
d ₁₄ 2.79 8.13 8.51
d ₁₆ 2.64 3.14 2.93

Example 6

r ₁ = 62.175 d ₁ = 0.80 n _d1 = 2.00170 ν _d1 = 20.64
r ₂ = 30.238 d ₂ = 0.10
r ₃ = 22.683 d ₃ = 2.74 n _d2 = 1.76802 ν _d2 = 49.24
r ₄ = -70.003 (aspherical surface) d ₄ = (variable)
r ₅ = -21.636 (aspherical surface) d ₅ = 0.87 n _d3 = 1.83481 ν _d3 = 42.71
r ₆ = 5.619 (aspherical surface) d ₆ = 2.02
r ₇ = 11.015 d ₇ = 2.12 n _d4 = 1.94595 ν _d4 = 17.98
r ₈ = 28.744 d ₈ = (variable)
r ₉ = ∞ (aperture) d ₉ = 0.10
r ₁₀ = 4.673 (aspherical surface) d ₁₀ = 2.61 n _d5 = 1.58913 ν _d5 = 61.14
r ₁₁ = -14.486 (aspherical surface) d ₁₁ = 0.10
r ₁₂ = 6.566 d ₁₂ = 1.30 n _d6 = 1.67790 ν _d6 = 50.72
r ₁₃ = 28.591 d ₁₃ = 0.80 n _d7 = 2.00069 ν _d7 = 25.46
r ₁₄ = 3.627 d ₁₄ = (variable)
r ₁₅ = 13.996 (aspherical surface) d ₁₅ = 2.07 n _d8 = 1.74330 ν _d8 = 49.33
r ₁₆ = -127.391 d ₁₆ = (variable)
r ₁₇ = ∞ d ₁₇ = 0.40 n _d9 = 1.54771 ν _d9 = 62.84
r ₁₈ = ∞ d ₁₈ = 0.50
r ₁₉ = ∞ d ₁₉ = 0.50 n _d10 = 1.51633 ν _d10 = 64.14
r ₂₀ = ∞ d ₂₀ = 0.35
r ₂₁ = ∞ (imaging surface)

Aspheric coefficient 4th surface R = -70.003
K = 0.000
A ₄ = 1.20840e-05
A ₆ = 7.76197e-08
A ₈ = -1.68487e-09
A ₁₀ = 1.05563e-11

5th surface R = -21.636
K = 0.004
A ₄ = 4.00902e-04
A ₆ = -7.46870e-06
A ₈ = 7.98424e-08
A ₁₀ = -2.55494e-10

6th surface R = 5.619
K = -0.119
A ₄ = -1.83831e-04
A ₆ = 1.27460e-05
A ₈ = -1.17445e-06
A ₁₀ = 9.45337e-09

Tenth face R = 4.673
K = -0.080
A ₄ = -3.64410e-04
A ₆ = 3.88128e-05
A ₈ = 3.87823e-06
A ₁₀ = 7.28414e-07

11th surface R = -14.486
K = 0.000
A ₄ = 1.77598e-03
A ₆ = 8.31238e-05
A ₈ = 9.04999e-06
A ₁₀ = 1.61068e-06

15th surface R = 13.996
K = 0.000
A ₄ = -4.62486e-05
A ₆ = 2.50668e-05
A ₈ = -1.31854e-06
A ₁₀ = 2.85912e-08

Zoom data (∞)
WE ST TE
f (mm) 5.06 12.03 24.30
F _NO 3.38 4.95 5.05
2ω (°) 80.22 35.50 17.42
d ₄ 0.67 4.59 15.71
d ₈ 12.79 4.54 1.39
d ₁₄ 2.79 8.12 8.57
d ₁₆ 2.63 3.11 2.92

Example 7

r ₁ = 94.096 d ₁ = 0.80 n _d1 = 2.00170 ν _d1 = 20.64
r ₂ = 36.640 d ₂ = 0.10
r ₃ = 23.265 d ₃ = 2.68 n _d2 = 1.76802 ν _d2 = 49.24
r ₄ = -65.988 (aspherical surface) d ₄ = (variable)
r ₅ = -20.758 (aspherical surface) d ₅ = 0.87 n _d3 = 1.88300 ν _d3 = 40.76
r ₆ = 5.946 (aspherical surface) d ₆ = 2.00
r ₇ = 13.375 d ₇ = 1.88 n _d4 = 2.10227 ν _d4 = 17.10
r ₈ = 42.000 d ₈ = (variable)
r ₉ = ∞ (aperture) d ₉ = 0.10
r ₁₀ = 4.646 (aspherical surface) d ₁₀ = 2.61 n _d5 = 1.58913 ν _d5 = 61.14
r ₁₁ = -14.474 (aspherical surface) d ₁₁ = 0.10
r ₁₂ = 6.683 d ₁₂ = 1.31 n _d6 = 1.67790 ν _d6 = 50.72
r ₁₃ = 34.534 d ₁₃ = 0.80 n _d7 = 2.00069 ν _d7 = 25.46
r ₁₄ = 3.633 d ₁₄ = (variable)
r ₁₅ = 14.262 (aspherical surface) d ₁₅ = 2.07 n _d8 = 1.74330 ν _d8 = 49.33
r ₁₆ = -68.293 d ₁₆ = (variable)
r ₁₇ = ∞ d ₁₇ = 0.40 n _d9 = 1.54771 ν _d9 = 62.84
r ₁₈ = ∞ d ₁₈ = 0.50
r ₁₉ = ∞ d ₁₉ = 0.50 n _d10 = 1.51633 ν _d10 = 64.14
r ₂₀ = ∞ d ₂₀ 0.40
r ₂₁ = ∞ (imaging surface)

Aspheric coefficient 4th surface R = -65.988
K = 0.000
A ₄ = 1.39994e-05
A ₆ = 4.31110e-08
A ₈ = -9.73594e-10
A ₁₀ = 5.44916e-12

5th surface R = -20.758
K = 0.005
A ₄ = 3.78537e-04
A ₆ = -5.56165e-06
A ₈ = 2.61919e-08
A ₁₀ = 2.68069e-10

6th surface R = 5.946
K = -0.124
A ₄ = -2.24793e-04
A ₆ = 1.51367e-05
A ₈ = -1.22207e-06
A ₁₀ = 1.37423e-08

Tenth face R = 4.646
K = -0.078
A ₄ = -3.99703e-04
A ₆ = 3.77334e-05
A ₈ = 3.98996e-06
A ₁₀ = 7.39900e-07

11th surface R = -14.474
K = 0.000
A ₄ = 1.73950e-03
A ₆ = 8.20306e-05
A ₈ = 9.91441e-06
A ₁₀ = 1.46222e-06

15th surface R = 14.262
K = 0.000
A ₄ = -6.90526e-05
A ₆ = 2.21932e-05
A ₈ = -9.10533e-07
A ₁₀ = 1.48759e-08

Zoom data (∞)
WE ST TE
f (mm) 5.06 11.93 24.27
F _NO 3.40 4.98 5.05
2ω (°) 80.76 35.88 17.48
d ₄ 0.67 4.54 15.84
d ₈ 12.77 4.58 1.31
d ₁₄ 2.83 8.28 8.63
d ₁₆ 2.62 3.08 2.92

Example 8

r ₁ = 58.074 d ₁ = 0.80 n _d1 = 2.00170 ν _d1 = 20.64
r ₂ = 29.126 d ₂ = 0.10
r ₃ = 22.139 d ₃ = 2.59 n _d2 = 1.76802 ν _d2 = 49.24
r ₄ = -78.668 (aspherical surface) d ₄ = (variable)
r ₅ = -25.718 (aspherical surface) d ₅ = 0.87 n _d3 = 1.88300 ν _d3 = 40.76
r ₆ = 5.522 (aspherical surface) d ₆ = 1.79
r ₇ = 10.009 d ₇ = 2.14 n _d4 = 1.94595 ν _d4 = 17.98
r ₈ = 26.958 d ₈ = (variable)
r ₉ = ∞ (aperture) d ₉ = 1.56
r ₁₀ = 5.426 (aspherical surface) d ₁₀ = 2.61 n _d5 = 1.58913 ν _d5 = 61.14
r ₁₁ = -11.325 (aspherical surface) d ₁₁ = 0.10
r ₁₂ = 6.525 d ₁₂ = 1.54 n _d6 = 1.69680 ν _d6 = 55.53
r ₁₃ = 23.505 d ₁₃ = 0.80 n _d7 = 2.00069 ν _d7 = 25.46
r ₁₄ = 3.652 d ₁₄ = (variable)
r ₁₅ = 14.723 (aspherical surface) d ₁₅ = 2.07 n _d8 = 1.74330 ν _d8 = 49.33
r ₁₆ = -65.589 d ₁₆ = (variable)
r ₁₇ = ∞ d ₁₇ = 0.40 n _d9 = 1.54771 ν _d9 = 62.84
r ₁₈ = ∞ d ₁₈ = 0.50
r ₁₉ = ∞ d ₁₉ = 0.50 n _d10 = 1.51633 ν _d10 = 64.14
r ₂₀ = ∞ d ₂₀ = 0.35
r ₂₁ = ∞ (imaging surface)

Aspheric coefficient 4th surface R = -78.668
K = 0.000
A ₄ = 1.24220e-05
A ₆ = 2.39631e-08
A ₈ = -6.58210e-10
A ₁₀ = 3.80349e-12

5th surface R = -25.718
K = 0.004
A ₄ = 4.03510e-04
A ₆ = -1.13800e-05
A ₈ = 1.76519e-07
A ₁₀ = -9.01353e-10

6th surface R = 5.522
K = -0.098
A ₄ = -1.95478e-04
A ₆ = 1.65430e-05
A ₈ = -2.04581e-06
A ₁₀ = 3.13050e-08

Tenth face R = 5.426
K = -0.062
A ₄ = -7.09426e-04
A ₆ = 1.45894e-05
A ₈ = -1.51869e-06
A ₁₀ = 3.20154e-07

11th surface R = -11.325
K = 0.000
A ₄ = 7.97676e-04
A ₆ = 3.43174e-05
A ₈ = -2.71403e-06
A ₁₀ = 4.90147e-07

15th surface R = 14.723
K = 0.000
A ₄ = -3.54230e-05
A ₆ = 1.63624e-05
A ₈ = -6.04370e-07
A ₁₀ = 9.12960e-09

Zoom data (∞)
WE ST TE
f (mm) 5.06 11.98 24.27
F _NO 3.16 4.67 5.05
2ω (°) 80.53 35.52 17.46
d ₄ 0.64 4.47 15.72
d ₈ 11.04 3.51 1.29
d ₁₄ 2.77 8.06 8.79
d ₁₆ 2.60 3.16 2.95

Example 9

r ₁ = 99.053 d ₁ = 0.80 n _d1 = 2.00170 ν _d1 = 20.64
r ₂ = 36.640 d ₂ = 0.10
r ₃ = 23.602 d ₃ = 2.72 n _d2 = 1.76802 ν _d2 = 49.24
r ₄ = -61.570 (aspherical surface) d ₄ = (variable)
r ₅ = -18.955 (aspherical surface) d ₅ = 0.84 n _d3 = 1.81600 ν _d3 = 46.62
r ₆ = 6.082 (aspherical surface) d ₆ = 2.15
r ₇ = 15.037 d ₇ = 1.72 n _d4 = 2.10227 ν _d4 = 17.10
r ₈ = 42.000 d ₈ = (variable)
r ₉ = ∞ (aperture) d ₉ = 0.10
r ₁₀ = 4.594 (aspherical surface) d ₁₀ = 2.61 n _d5 = 1.58913 ν _d5 = 61.14
r ₁₁ = -14.782 (aspherical surface) d ₁₁ = 0.10
r ₁₂ = 7.013 d ₁₂ = 1.29 n _d6 = 1.67790 ν _d6 = 50.72
r ₁₃ = 35.080 d ₁₃ = 0.80 n _d7 = 2.00069 ν _d7 = 25.46
r ₁₄ = 3.735 d ₁₄ = (variable)
r ₁₅ = 14.317 (aspherical surface) d ₁₅ = 2.07 n _d8 = 1.74330 ν _d8 = 49.33
r ₁₆ = -56.567 d ₁₆ = (variable)
r ₁₇ = ∞ d ₁₇ = 0.40 n _d9 = 1.54771 ν _d9 = 62.84
r ₁₈ = ∞ d ₁₈ = 0.50
r ₁₉ = ∞ d ₁₉ = 0.50 n _d10 = 1.51633 ν _d10 = 64.14
r ₂₀ = ∞ d ₂₀ = 0.37
r ₂₁ = ∞ (imaging surface)


Aspheric coefficient 4th surface R = -61.570
K = 0.000
A ₄ = 1.41315e-05
A ₆ = 4.18374e-08
A ₈ = -9.02777e-10
A ₁₀ = 4.86502e-12

5th surface R = -18.955
K = 0.005
A ₄ = 4.04887e-04
A ₆ = -6.53532e-06
A ₈ = 6.53892e-08
A ₁₀ = -1.64331e-10

6th surface R = 6.082
K = -0.124
A ₄ = -1.71542e-04
A ₆ = 1.45171e-05
A ₈ = -1.17570e-06
A ₁₀ = 1.72357e-08

Tenth face R = 4.594
K = -0.078
A ₄ = -3.30111e-04
A ₆ = 4.86037e-05
A ₈ = 3.10752e-06
A ₁₀ = 9.98370e-07

11th surface R = -14.782
K = 0.000
A ₄ = 1.89564e-03
A ₆ = 1.06499e-04
A ₈ = 6.77189e-06
A ₁₀ = 2.31800e-06

15th surface R = 14.317
K = 0.000
A ₄ = -7.77744e-05
A ₆ = 1.98878e-05
A ₈ = -7.24814e-07
A ₁₀ = 9.65808e-09

Zoom data (∞)
WE ST TE
f (mm) 5.06 11.89 24.27
F _NO 3.37 4.92 4.99
2ω (°) 81.17 35.94 17.43
d ₄ 0.67 4.57 15.91
d ₈ 12.76 4.53 1.15
d ₁₄ 2.81 8.30 8.66
d ₁₆ 2.67 3.09 2.96

  Aberration diagrams at the time of focusing on an object point at infinity in Examples 1 to 9 are shown in FIGS. In these aberration diagrams, (a) is a wide-angle end, (b) is an intermediate state, and (c) is spherical aberration, astigmatism, distortion, and lateral chromatic aberration at a telephoto end. In each figure, “FIY” indicates the maximum image height.

Next, the value of each conditional expression in each embodiment will be listed.
(Value of conditional expression)

Example 1 Example 2 Example 3 Example 4 Example 5
(1) n _d2n 1.88300 1.80495 1.80495 1.80495 1.88300
(2) ν _d2n 40.76 40.9 40.9 40.9 40.76
_{(A) | f 1n | /} f t 2.697 1.579 1.367 2.042 2.425
(B) | f _2n | / f _t 0.162 0.163 0.166 0.148 0.209
(C) | f _1n | / | f _2n | 16.63 9.67 8.26 13.84 11.59
(D) | f _1n | / f _1p 3.368 2.421 2.363 3.053 2.616
(3) SF _2p -1.955 -2.593 -2.667 -2.542 -1.902
(4) | f ₂ / f _t | 0.273 0.266 0.270 0.255 0.351
(5) n _d2p 1.92286 1.92286 1.92286 2.0017 1.94595
(6) ν _d2p 18.90 18.90 18.90 20.64 17.98
(7) SF _2n 0.663 0.568 0.624 0.616 0.602
(8) (| asp _2nf | + | asp _2nr |) / f _w
0.054 0.059 0.057 0.090 0.131
(9) L _1np / L _{1 0.079-0.095} 0.077 0.028
(10) f ₁ / f _t 1.161 1.145 1.010 1.021 1.492
(11) f ₃ / _ft 0.326 0.314 0.333 0.328 0.381
(12) f ₄ / _ft 0.586 0.539 0.490 0.502 0.594
(13) f _t / f _w 4.810 4.800 4.847 4.781 4.791


Example 6 Example 7 Example 8 Example 9
(1) n _d2n 1.83481 1.88300 1.88300 1.81600
(2) ν _d2n 42.71 40.76 40.76 46.62
_{(A) | f 1n | /} f t 2.449 2.486 2.438 2.407
_{(B) | f 2n | /} f t 0.217 0.212 0.209 0.229
(C) | f _1n | / | f _2n | 11.30 11.70 11.64 10.51
(D) | f _1n | / f _1p 2.634 2.658 2.600 2.594
(3) SF _2p -2.243 -1.935 -2.181 -2.115
(4) | f ₂ / f _t | 0.348 0.353 0.349 0.357
(5) n _d2p 1.94595 2.10226 1.94595 2.10226
(6) ν _d2p 17.98 17.10 17.98 17.1
(7) SF _2n 0.588 0.555 0.646 0.5142
(8) (| asp _2nf | + | asp _2nr |) / f _w
0.150 0.124 0.108 0.1180
(9) L _1np / L ₁ 0.027 0.028 0.029 0.028
(10) f ₁ / f _t 1.495 1.489 1.523 1.4984
(11) f ₃ / _ft 0.379 0.384 0.375 0.3870
(12) f ₄ / _ft 0.599 0.563 0.574 0.5459
(12) f _t / f _w 4.800 4.794 4.793 4.7947

  Next, effects of the above embodiments will be described. In each embodiment, a zoom lens optical system having a high zoom ratio of about 5 times is realized in consideration of facilitating thinning of the camera. In addition, a zoom lens optical system is realized in which the image quality of the photographed image is maintained well and is suitable for an electronic image pickup device such as a CCD or CMOS, and the number of constituent lenses is reduced. As a result, it is possible to satisfy the user's desire to expand the photographing area more than before without impairing the portability of the camera.

In the present invention and each embodiment, if the shutter unit that moves integrally with the aperture stop is provided, the shutter unit does not increase in size, and the dead space when the aperture stop and the shutter unit are moved. Is small.
Further, in order to cut unnecessary light such as ghosts and flares, a flare stop other than the brightness stop may be arranged.

The flare stop is disposed on the object side of the first lens group, between the first and second lens groups, between the second and third lens groups, between the third and fourth lens groups, and between the fourth lens group and the image plane. May be.
The frame member may be configured to cut flare rays, or another member may be configured. Also, it may be printed directly on the optical system, painted, or bonded with a seal. The shape may be any shape such as a circle, an ellipse, a rectangle, a polygon, or a range surrounded by a function curve. Further, not only harmful light beams but also light beams such as coma flare around the screen may be cut.

  Each lens may be provided with an anti-reflection coating to reduce ghosts and flares. A multi-coat is desirable because it can effectively reduce ghost and flare. Infrared cut coating may be applied to the lens surface, cover glass, or the like.

  Further, it is desirable to perform focusing for adjusting the focus by moving the fourth lens group. When focusing is performed with the fourth lens group, the load on the motor is small because the lens weight is light. Furthermore, the total length does not change during focusing, and the drive motor can be arranged inside the lens frame, which is advantageous for making the lens frame compact. Although focusing by moving the fourth lens group is desirable as described above, focusing may be performed by the first, second and third lens groups. Further, focusing may be performed by moving a plurality of lens groups. Further, focusing may be performed by extending the entire zoom lens system, or focusing may be performed by extending or retracting a part of the lenses.

  Further, the brightness (shading) at the periphery of the image may be reduced by shifting the CCD microlens. For example, the design of the CCD microlens may be changed according to the incident angle of the light beam at each image height. Further, the amount of decrease in the peripheral portion of the image may be corrected by image processing.

Alternatively, the distortion may be intentionally generated by the optical system, and the distortion may be corrected by electrically performing image processing after shooting.
If distortion and magnification are corrected individually for each color image of RGB, the chromatic aberration of magnification can be electrically corrected simultaneously.

  19 to 21 are conceptual diagrams of the configuration of a digital camera according to the present invention in which the zoom lens as described above is incorporated in the photographing optical system 141. FIG. 19 is a front perspective view showing the external appearance of the digital camera 140, FIG. 20 is a rear front view thereof, and FIG. 21 is a schematic sectional view showing the configuration of the digital camera 140. However, in FIGS. 19 and 21, the photographing optical system 141 is not retracted. In this example, the digital camera 140 includes a photographing optical system 141 having a photographing optical path 142, a finder optical system 143 having a finder optical path 144, a shutter button 145, a flash 146, a liquid crystal display monitor 147, a focal length change button 161, When the photographic optical system 141 is retracted, including the setting change switch 162, the photographic optical system 141, the finder optical system 143, and the flash 146 are covered with the cover 160 by sliding the cover 160. When the cover 160 is opened and the camera 140 is set to the photographing state, the photographing optical system 141 is brought into the non-collapsed state of FIG. Photographing is performed through the optical system 141, for example, the zoom lens of the first embodiment. An object image formed by the photographic optical system 141 is formed on the imaging surface of the CCD 149 through a low-pass filter F and a cover glass C that are provided with a wavelength band limiting coat. The object image received by the CCD 149 is displayed as an electronic image on a liquid crystal display monitor 147 provided on the back of the camera via the processing means 151. Further, the processing means 151 is connected to a recording means 152 so that a photographed electronic image can be recorded. The recording unit 152 may be provided separately from the processing unit 151, or may be configured to perform recording / writing electronically using a flexible disk, a memory card, an MO, or the like. Further, instead of the CCD 149, a silver salt camera in which a silver salt film is arranged may be configured.

  Further, a finder objective optical system 153 is disposed on the finder optical path 144. The finder objective optical system 153 includes a plurality of lens groups (three groups in the figure) and two prisms, and includes a zoom optical system whose focal length changes in conjunction with the zoom lens of the photographing optical system 141. The object image formed by the finder objective optical system 153 is formed on the field frame 157 of the erecting prism 155 that is an image erecting member. Behind the erecting prism 155, an eyepiece optical system 159 that guides the erect image to the observer eyeball E is disposed. A cover member 150 is disposed on the exit side of the eyepiece optical system 159.

  The digital camera 140 configured as described above has a high performance because the photographing optical system 141 is extremely thin when retracted, and has a high zoom ratio and a very stable imaging performance in the entire zoom range.・ Compact and wide angle can be realized.

  According to the present invention, it is possible to realize a zoom lens optical system having a high zoom ratio of about 5 times, which is designed so that the camera can be easily thinned. Of course, the image quality of the captured image is maintained well, and it is useful for an electronic image sensor such as a CCD or CMOS.

FIG. 2 is a lens cross-sectional view at the wide-angle end (a), the intermediate state (b), and the telephoto end (c) when focusing on an object point at infinity according to the first exemplary embodiment of the zoom lens of the present invention. It is the same figure as FIG. 1 of Example 2 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 3 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 4 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 5 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 6 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 7 of the zoom lens of this invention. It is a figure similar to FIG. 1 of Example 8 of the zoom lens of this invention. It is the same figure as FIG. 1 of Example 9 of the zoom lens of this invention. FIG. 6 is an aberration diagram for Example 1 upon focusing on an object point at infinity. FIG. 6 is an aberration diagram for Example 2 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 3 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 4 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 5 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 6 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 7 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 8 upon focusing on an object point at infinity. FIG. 10 is an aberration diagram for Example 9 upon focusing on an object point at infinity. It is a front perspective view which shows the external appearance of the digital camera by this invention. FIG. 20 is a rear perspective view of the digital camera of FIG. 19. It is sectional drawing of the digital camera of FIG.

Explanation of symbols

G1 ... 1st lens group G2 ... 2nd lens group G3 ... 3rd lens group G4 ... 4th lens group S ... Aperture stop F ... Low pass filter C ... Cover glass I ... Image surface 140 ... Digital camera 141 ... Shooting optical system 142 Optical path for photographing 143 Optical system for viewfinder 144 Optical path for viewfinder 145 Shutter button 146 Flash 147 Liquid crystal display monitor 149 CCD
150: cover member 151 ... processing means 152 ... recording means 153 ... finder objective optical system 155 ... erecting prism 157 ... field frame 159 ... eyepiece optical system 160 ... cover 161 ... focal length change button 162 ... setting change switch

Claims (26)

From the object side,
A first lens unit having positive refractive power;
A second lens unit having negative refractive power;
A third lens unit having positive refractive power;
A fourth lens group having positive refractive power and a,
During zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases , the distance between the second lens group and the third lens group decreases , and the third lens group decreases . The first lens group, the second lens group, the third lens group, and the fourth lens group move so that an interval between the lens group and the fourth lens group is widened.
An aperture stop that moves in the optical axis direction together with the third lens group at the time of zooming ;
The first lens group consists of two lenses, a positive lens and a negative lens,
The second lens group is composed of two lenses, a negative lens and a positive lens in order from the object side.
The negative lens of the second lens group is a biconcave lens;
A zoom lens satisfying the following conditional expression:
1.78 <n _d2n <2.10 (1)
35.0 <ν _d2n <50.0 (2)
0.35 <SF _2n <0.70 (7) ′
However,
n _d2n is the refractive index of the negative lens in the second lens group with respect to the d-line,
ν _d2n is the Abbe number of the negative lens in the second lens group,
SF _2n = (R _2nf + R _2nr ) / (R _2nf −R _2nr )
R _2nf is the paraxial radius of curvature of the object side surface of the negative lens in the second lens group,
R _2nr is the paraxial radius of curvature of the image side surface of the negative lens in the second lens group,
It is. The zoom lens according to claim 1, wherein the following condition is satisfied.
_{0.6 <| f 1n | / f} t <5.0 (A)
0.08 <| f _2n | / _ft <0.35 (B)
5.0 <| f _1n | / | f _2n | <25.0 (C)
However,
f _1n is the focal length of the negative lens in the first lens group,
f _2n is the focal length of the negative lens in the second lens group,
f _t is the focal length of the entire zoom lens system at the telephoto end,
It is. The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
1.4 <| f _1n | / f _1p <4.5 (D)
However,
f _1p is the focal length of the positive lens in the first lens group,
f _1n is the focal length of the negative lens in the first lens group,
It is. 4. The zoom lens according to claim 1, wherein the positive lens of the second lens group is a meniscus lens convex toward the object side that satisfies the following conditional expression. 5.
−5.0 <SF _2p <−1.0 (3)
However,
SF _2p = (R _2pf + R _2pr ) / (R _2pf −R _2pr )
R _2pf is the paraxial radius of curvature of the object side surface of the positive lens in the second lens group,
R _2pr is a paraxial radius of curvature of the image side surface of the positive lens in the second lens group,
It is. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.12 <| f ₂ / f _t | <0.60 (4)
However,
f ₂ is the focal length of the second lens group,
_ft is the focal length of the entire zoom lens system at the telephoto end,
It is. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
1.88 <n _d2p <2.20 (5)
13.0 <ν _d2p <30.0 (6)
However,
n _d2p is the refractive index of the positive lens in the second lens group with respect to the d-line,
ν _d2p is the Abbe number of the positive lens in the second lens group,
It is. Wherein at least one lens surface of the negative lens in the second lens group are aspherical zoom lens according to any one of 請 Motomeko 1-6 you and satisfies the following condition .
0.030 <(| asp _2nf | + | asp _2nr |) / f _w <0.320 (8)
However,
asp _2nf is the amount of aspherical deviation on the object-side lens surface of the negative lens in the second lens group,
asp _2nr is the amount of aspherical deviation on the image side lens surface of the negative lens in the second lens group,
f _w is the focal length of the entire zoom lens system at the wide-angle end,
It is.   The zoom lens according to claim 7, wherein an aspheric surface of the negative lens in the second lens group is an aspheric surface whose refractive power increases as the distance from the optical axis increases.   7. The zoom lens according to claim 6, wherein the object side surface and the image side surface of the biconcave lens in the second lens group are both aspherical surfaces whose refractive power increases as they move away from the optical axis.   The zoom lens according to claim 1, wherein the first lens group includes two lenses of the negative lens and the positive lens in order from the object side.   The zoom lens according to claim 10, wherein the negative lens and the positive lens in the first lens group are cemented.   The zoom lens according to claim 10, wherein each of the negative lens and the positive lens in the first lens group is a single lens. The zoom lens according to claim 12, wherein an on-axis distance between the negative lens and the positive lens in the first lens group satisfies the following conditional expression.
0.0 ≦ L _1np / L ₁ <0.2 (9)
However,
L _1np is the axial distance between the negative lens and the positive lens in the first lens group,
L ₁ is the total thickness on the axis of the first lens group,
It is.   The zoom lens according to claim 1, wherein the third lens group includes three or less lenses.   The zoom lens according to claim 14, wherein the third lens group includes two lenses of a positive lens and a negative lens in order from the object side.   The zoom lens according to claim 14, wherein the third lens group includes three lenses of a positive lens, a positive lens, and a negative lens in order from the object side.   The zoom lens according to claim 16, wherein the negative lens of the third lens group is cemented with the positive lens on an adjacent object side. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
_{0.50 <f 1 / f t <} 2.00 ··· (10)
However,
f ₁ is the focal length of the first lens group,
_ft is the focal length of the entire zoom lens system at the telephoto end,
It is. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
_{0.16 <f 3 / f t <} 0.80 ··· (11)
However,
f ₃ is the focal length of the third lens group,
_ft is the focal length of the entire zoom lens system at the telephoto end,
It is. The zoom lens according to at least any one of 請 Motomeko 1-19 you and satisfies the following conditional expression.
_{0.24 <f 4 / f t <} 0.80 ··· (12)
However,
f ₄ is the focal length of the fourth lens group,
_ft is the focal length of the entire zoom lens system at the telephoto end,
It is. When zooming from the wide-angle end to the telephoto end,
The first lens group moves so as to be closer to the object side at the telephoto end than at the wide angle end,
The second lens group moves;
The third lens group moves only to the object side,
The fourth group moves,
2. The aperture stop is located between the second lens group and the third lens group, and moves in the optical axis direction integrally with the third lens group at the time of zooming. 21. The zoom lens according to at least one of 20. The zoom lens according to any one of claims 1 to 21, wherein the zoom lens is a four-group zoom lens. The zoom lens according to any one of claims 1 to 22, wherein the following conditional expression is satisfied.
3.8 <f _t / F _w <10.0 ... (13)
However,
f _w Is the focal length of the entire zoom lens at the wide-angle end,
f _t Is the focal length of the entire zoom lens at the telephoto end,
It is. The zoom lens according to at least one of claims 1 to 23;
An electronic image pickup device, comprising: an electronic image pickup device that is disposed on an image side of the zoom lens and converts an optical image formed by the zoom lens into an electric signal. From the object side,
A first lens unit having positive refractive power;
A second lens unit having negative refractive power;
A third lens unit having positive refractive power;
A fourth lens unit having a positive refractive power,
During zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the third lens group decreases. The first lens group, the second lens group, the third lens group, and the fourth lens group move so that an interval between the lens group and the fourth lens group is widened.
An aperture stop that moves in the optical axis direction together with the third lens group at the time of zooming ;
The first lens group consists of two lenses, a positive lens and a negative lens,
The negative lens and the positive lens in the first lens group are each a single lens,
The second lens group is composed of two lenses, a negative lens and a positive lens in order from the object side.
A zoom lens satisfying the following conditional expression:
1.78 <n _d2n <2.10 (1)
35.0 <ν _d2n <50.0 (2)
However,
n _d2n is the refractive index of the negative lens in the second lens group with respect to the d-line,
ν _d2n is the Abbe number of the negative lens in the second lens group,
It is. From the object side,
A first lens unit having positive refractive power;
A second lens unit having negative refractive power;
A third lens unit having positive refractive power;
A fourth lens unit having a positive refractive power,
During zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the third lens group decreases. The first lens group, the second lens group, the third lens group, and the fourth lens group move so that an interval between the lens group and the fourth lens group is widened.
An aperture stop that moves in the optical axis direction together with the third lens group at the time of zooming ;
The first lens group consists of two lenses, a positive lens and a negative lens,
The second lens group is composed of two lenses, a negative lens and a positive lens in order from the object side.
The third lens group is composed of two lenses, a positive lens and a negative lens, in order from the object side.
A zoom lens satisfying the following conditional expression:
1.78 <n _d2n <2.10 (1)
35.0 <ν _d2n <50.0 (2)
However,
n _d2n is the refractive index of the negative lens in the second lens group with respect to the d-line,
ν _d2n is the Abbe number of the negative lens in the second lens group,
It is.

Images