JP4669294B2

JP4669294B2 - Zoom lens and imaging apparatus having the same

Info

Publication number: JP4669294B2
Application number: JP2005022561A
Authority: JP
Inventors: 大介伊藤
Original assignee: キヤノン株式会社
Priority date: 2005-01-31
Filing date: 2005-01-31
Publication date: 2011-04-13
Anticipated expiration: 2025-01-31
Also published as: JP2006208890A

Description

The present invention relates to a zoom lens, for example, a zoom lens suitable for a photographing optical system such as a digital still camera.

Recently, with the enhancement of functions of image pickup apparatuses (cameras) such as video cameras and digital still cameras using solid-state image pickup devices, a zoom lens having a large aperture ratio including a wide shooting angle of view is required for an optical system used therefor. ing.

Furthermore, in this type of camera, various optical members such as a low-pass filter and a color correction filter are arranged between the rearmost lens part and the image sensor, so that the optical system used therefor has a lens system with a relatively long back focus. Is required. In addition, in the case of a camera using a color image pickup device, in order to avoid color shading, an optical system having good image side telecentric characteristics is desired to be used.

2. Description of the Related Art Conventionally, there is a so-called short zoom type two-group zoom lens that includes two lens groups, a first lens unit having a negative refractive power and a second lens group having a positive refractive power, and performs zooming by changing the distance between the two lenses. Various proposals have been made. In these short zoom type optical systems, zooming is performed by moving the second lens group having a positive refractive power, and fluctuations are caused by zooming by moving the first lens group having a negative refractive power. Image position compensation is performed. In the lens configuration including these two lens groups, the zoom ratio is about twice.

In order to bring the entire lens into a compact shape while having a zoom ratio of 2 times or more, a third lens group having a negative or positive refractive power is arranged on the image side of the second group zoom lens to increase the zoom ratio. A so-called three-group zoom lens has also been proposed (for example, Patent Documents 1 and 2).

A three-group zoom lens system having a long back focus and satisfying telecentric characteristics is also known as a three-group zoom lens (for example, Patent Documents 3 and 4).

Further, in a three-group zoom lens composed of lens groups having negative, positive, and positive refractive powers, the first lens group having negative refractive power is fixed during zooming, and the second lens group having positive refractive power and positive refractive power. A three-group zoom lens that performs zooming by moving the third lens group of force is known (for example, Patent Document 5).

In addition, in a three-group zoom lens composed of negative, positive, and positive refractive power lens groups, a three-group zoom lens is known in which the second lens group is composed of a positive lens, a positive lens, a negative lens, and a positive lens ( For example, Patent Documents 6 to 13).

In addition, a zoom lens having a high zoom ratio with a zoom ratio of 3 or more is known (for example, Patent Documents 14 to 23).
Japanese Patent Publication No. 7-3507 Japanese Patent Publication No. 6-40170 JP-A 63-135913 Japanese Patent Laid-Open No. 7-261083 JP-A-3-288113 JP-A-9-258103 JP 11-52246 A JP-A-11-174322 JP-A-11-174322 Japanese Patent Application Laid-Open No. 11-194274 Japanese Patent No. 3466385 JP 2002-23053 A JP 2002-196240 A JP-A-4-217219 Japanese Patent Laid-Open No. 10-039214 Japanese Patent No. 10-213745 JP-A-11-119101 JP-A-11-174322 JP 2001-42218 A Japanese Patent No. 2002-3655545 JP 2002-267930 A JP2003-156686A Japanese Patent No. 2895843

A three-group zoom lens designed for 35 mm film photography has an excessively long back focus and poor telecentric characteristics for use in an imaging device using a solid-state imaging device. It is difficult to use as it is.

On the other hand, in order to achieve both compactness of the camera and high zoom ratio (higher magnification) of the zoom lens, the distance between the lens groups is reduced to a different distance from the shooting state during non-shooting, and the amount of lens protrusion from the camera body A so-called collapsible zoom lens with a reduced number of lenses is widely used.

In general, if the number of lenses in each lens group constituting the zoom lens is large, the length of each lens group on the optical axis becomes long, and if the amount of movement of each lens group in zooming and focusing is large, the total lens length becomes long. Therefore, the desired retractable length cannot be achieved, and it becomes difficult to use the retractable zoom lens.

This tendency becomes more prominent as the zoom ratio of the zoom lens increases.

An object of the present invention is to provide a zoom lens that has a relatively small number of constituent lenses, has a desired angle of view at the wide-angle end, and realizes a desired zoom ratio, and an imaging apparatus having the same.

The zoom lens of the present invention includes, in order from the object side to the image side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having positive refractive power, hand during zooming in the zoom lens the distance of each lens group is changed, the wide-angle end from Δ2X the amount of movement of the second lens group during zooming to the telephoto end, the distance between the third lens group and the second lens group at the wide-angle end d23w, the first lens group and the focal length of the second lens group respectively f1, f2, the focal length of the entire system at the wide angle end fw, the average of the refractive index of the material of the lenses constituting the first lens group When the value is n1a ,
1.7 <Δ2X / √ | f1 · f2 | <2.3
0.5 <D23w / fw <1.2
1.88 <n1a
It is characterized by satisfying the following conditions.

In addition, the zoom lens of the present invention includes, in order from the object side to the image side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. in the zoom lens hand spacing of each lens group is changed upon zooming, the first lens group consists of two lenses, Deruta2X the amount of movement of the second lens group during zooming to the telephoto end from the wide angle end, the first each one lens group is a focal length of the second lens group f1, f2, when an average value of the refractive index of the material of the lenses constituting the first lens group and n1a,
1.7 <Δ2X / √ | f1 · f2 | <2.3
1.88 <n1a
It is characterized by satisfying the following conditions.

In addition, the zoom lens of the present invention includes, in order from the object side to the image side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. in the zoom lens hand spacing of each lens group is changed upon zooming, Deruta2X the amount of movement of the second lens group during zooming from the wide-angle end to the telephoto end, and the second lens group at the wide-angle end and the third lens group D23w spacing, the first lens group and the focal length of the second lens group respectively f1, f2, the focal length of the entire system at the wide angle end fw, the material of the negative lens constituting the second lens group When the refractive index is n2b ,
1.7 <Δ2X / √ | f1 · f2 | <2.3
0.5 <D23w / fw <1.2
1.85 <n2b
It is characterized by satisfying the following conditions.

In addition, the zoom lens of the present invention includes, in order from the object side to the image side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. in the zoom lens hand spacing of each lens group is changed upon zooming, the first lens group consists of two lenses, Deruta2X the amount of movement of the second lens group during zooming to the telephoto end from the wide angle end, the first each one lens group is a focal length of the second lens group f1, f2, when the refractive index of the material of the negative lens constituting the second lens group and n2b,
1.7 <Δ2X / √ | f1 · f2 | <2.3
1.85 <n2b
It is characterized by satisfying the following conditions.

According to the present invention, a zoom lens having a relatively small number of constituent lenses, a wide angle of view, and a high zoom ratio can be obtained.

Embodiments of the zoom lens of the present invention and an image pickup apparatus having the same will be described below.

FIG. 1 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to Embodiment 1 of the present invention, and FIGS. 2, 3 and 4 are zoom positions at the wide-angle end and intermediate position of the zoom lens according to Embodiment 1, respectively. FIG. 6 is an aberration diagram at the telephoto end (long focal length end). The first embodiment is a zoom lens having a zoom ratio of about 4.6 and an aperture ratio of about 2.6 to 6.0.

FIG. 5 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 2 of the present invention. FIGS. 6, 7, and 8 are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively. It is. The second embodiment is a zoom lens having a zoom ratio of 5.4 and an aperture ratio of about 2.7 to 7.0.

9 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 3 of the present invention. FIGS. 10, 11 and 12 are aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end of the zoom lens according to Embodiment 3, respectively. It is. The third exemplary embodiment is a zoom lens having a zoom ratio of 5.9 and an aperture ratio of about 2.5 to 6.9.

FIG. 13 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 4 of the present invention, and FIGS. 14, 15, and 16 are aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end, respectively. It is. Example 4 is a zoom lens having a zoom ratio of 4.6 and an aperture ratio of about 2.5 to 6.0.

FIG. 17 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 5 of the present invention. FIGS. 18, 19, and 20 are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively. It is. The fifth embodiment is a zoom lens having a zoom ratio of 4.6 and an aperture ratio of about 2.5 to 6.0.

FIG. 21 is a schematic diagram of a main part of a digital still camera (imaging device) including the zoom lens of the present invention.

The zoom lens of each embodiment is a photographic lens system used in an imaging apparatus. In the lens cross-sectional view, the left side is the object side (front) and the right side is the image side (rear).

In the lens cross-sectional views of FIGS. 1, 5, 9, 13, and 17, L1 is a first lens unit having a negative refractive power (optical power = reciprocal of focal length), and L2 is a positive refractive power. Two lens units, L3 is a third lens unit having a positive refractive power, SP is an aperture stop, and is disposed on the object side of the second lens unit L2.

G is an optical block corresponding to an optical filter, a face plate, a quartz low-pass filter, an infrared cut filter, or the like. IP is an image plane, and when used as a photographing optical system of a video camera or a digital still camera, a photosensitive surface corresponding to an imaging surface of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is placed.

In the aberration diagrams, d and g are d-line and g-line, ΔM and ΔS are meridional image surface, sagittal image surface, and lateral chromatic aberration are represented by g-line.

In each of the following embodiments, the wide-angle end and the telephoto end refer to zoom positions when the zoom lens unit (second lens unit L2) is positioned at both ends of the range in which it can move on the optical axis due to the mechanism.

In the zoom lens of each embodiment, during zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves substantially reciprocally along a locus convex to the image side, the second lens unit L2 moves to the object side, The three lens unit L3 moves to the image side.

The zoom lens of each embodiment performs main zooming by movement of the second lens unit L2, and an image accompanying zooming by reciprocating movement of the first lens unit L1 and movement in the image side direction by the third lens unit L3. The movement is corrected.

Next, specific features of the lens configuration will be described.

The first lens unit L1 includes, in order from the object side to the image side, a meniscus negative lens G11 having a convex surface facing the object side and a meniscus positive lens G12 having a convex surface facing the object side. is doing.

The first lens unit L1 has a role of forming an off-axis chief ray at the center of the aperture stop SP and forms a pupil image. Especially on the wide-angle side, the off-axis chief ray has a large amount of refraction, and various off-axis aberrations, particularly non- Point aberration and distortion are likely to occur.

Therefore, in each embodiment, as with a normal wide-angle lens, a lens configuration of a negative lens and a positive lens that can suppress an increase in the lens diameter closest to the object side is adopted.

Then, by making the lens surface on the image side of the negative lens G11 an aspherical shape in which the negative refractive power is weakened around the lens, astigmatism and distortion are corrected in a well-balanced manner and the number of lenses as small as two is reduced. The first lens unit L1 is configured to make the entire lens compact.

Each lens constituting the first lens unit L1 has a lens shape close to a concentric sphere centered on the point where the aperture stop SP intersects the optical axis in order to suppress the occurrence of off-axis aberration caused by refraction of the off-axis principal ray. It is said.

In order from the object side to the image side, the second lens unit L2 includes a positive lens G21 having a convex surface on the object side, a positive lens G22 having a convex shape on both lens surfaces, and a negative lens G23 having a concave shape on both lens surfaces. It is composed of a cemented cemented lens and a positive lens G24.

The second lens unit L2 includes a positive lens G21 and a positive lens G22 disposed on the object side, reduces the refraction angle of the off-axis principal ray emitted from the first lens unit L1, and does not cause off-axis aberrations. It has a shape.

Further, the positive lens G21 is a lens having the highest height of the on-axis light beam, and is a lens mainly involved in correction of spherical aberration and coma aberration. Therefore, in each embodiment, the positive lens G21 and the positive lens G22 are arranged, and the spherical aberration and the coma are corrected well by gradually refracting the light beam.

And the aberration which generate | occur | produced with the positive lens G21 and the positive lens G22 is canceled by making the image side surface of the negative lens G23 cemented with the positive lens G22 into a concave shape.

The third lens unit L3 includes at least one positive lens G31 having a convex object-side surface. Each embodiment consists of a single positive lens.

The third lens group L3 shares the increase in the refractive power of each lens group accompanying the downsizing of the image sensor, and reduces the refractive power of the short zoom system composed of the first and second lens groups L1 and L2. In particular, good optical performance is achieved by suppressing the occurrence of aberration in each lens constituting the first lens unit L1. Further, telecentric imaging on the image side necessary for a photographing apparatus using a solid-state imaging device or the like is achieved by making the third lens unit L3 serve as a field lens.

Here, when the back focus is sk ′, the focal length of the third lens unit L3 is f3, and the imaging magnification of the third lens unit L3 is β3,
sk ′ = f3 (1-β3)
The relationship is established.

However,
0 <β3 <1.0
It is.

Here, when the third lens unit L3 is moved to the image side during zooming from the wide-angle end to the telephoto end, the back focus sk ′ is decreased, and the imaging magnification β3 of the third lens unit L3 is a zoom region on the telephoto side. Increase with. Then, as a result, the third lens unit L3 shares the variable magnification, and the amount of movement of the second lens unit L2 is reduced, and the space for this can be saved, contributing to the miniaturization of the lens system.

When shooting from an object at infinity to an object at a short distance using the zoom lens of each embodiment, it is possible to obtain good performance by moving the first lens unit L1 to the object side, but it is more desirable. It is better to focus by moving the third lens unit L3 to the object side.

This occurs when the first lens unit L1 arranged closest to the object side is moved by focusing. The increase of the front lens diameter and the load of the actuator by moving the first lens unit L1 having the heaviest lens weight are caused. This is because an increase can be prevented. In addition, by not moving the first lens unit L1 for focusing, the first lens unit L1 and the second lens unit L2 can be simply moved together by a cam or the like during zooming, and the mechanical structure is improved. Simplification and improved accuracy can be achieved.

When focusing is performed by the third lens unit L3, the third lens unit at the telephoto end having a large focusing movement amount is obtained by moving the third lens unit L3 to the image side during zooming from the wide-angle end to the telephoto end. Since the position of L3 can be arranged on the image side compared to the wide-angle end, the total amount of movement of the third lens unit L3 required for zooming and focusing can be minimized, and the lens system is compact. It becomes easy.

As described above, by making each lens group a lens configuration that achieves both desired refractive power arrangement and aberration correction, the entire lens system can be made compact, a high zoom ratio, and retracted while maintaining good optical performance. The length has been shortened.

In the zoom lens of each embodiment, in order to obtain good optical performance or to reduce the size of the entire lens system, at least one of the following conditions is satisfied. As a result, an effect equivalent to each conditional expression is obtained.

The amount of movement of the second lens unit L2 during zooming from the wide-angle end to the telephoto end is Δ2X (the sign of the amount of movement Δ2X is positive for movement toward the object side, and vice versa), and the second lens unit at the wide-angle end The distance between L2 and the third lens unit L4 is D23W, the focal lengths of the first lens unit L1, the second lens unit L2, and the third lens unit L3 are sequentially f1, f2, and f3, and the focal length of the entire system at the wide angle end. , The imaging magnifications at the wide-angle end and the telephoto end of the second lens unit L2 are β2w and β2t, respectively, and the imaging magnifications at the wide-angle end and the telephoto end of the third lens unit L3 are β3w, β3t, When the average value of the refractive index of the lens material constituting one lens group L1 is n1a, the second lens group L2 has a negative lens, and the material refractive index of the negative lens is n2b,

0.5 < D23w / fw < 1.2 (2)
3.8 <(β2t · β3 w ) / (β2 w · β3t)> 5.2 (3)
1.88 <n1a (4)
1.85 <n2b (5)
1.9 <f3 / f2 <2.5 (6)
5.2 <f3 / fw <6.4 (7)
Is satisfied.

When the movement amount Δ2X of the second lens unit L2 during zooming becomes smaller than the lower limit of the conditional expression (1), the power of the first lens unit L1 and the second lens unit L2 becomes loose, and a predetermined zoom ratio is secured. In addition, the amount of movement of each lens group increases, making it difficult to make the entire system compact.

When the upper limit value of conditional expression (1) is exceeded, the power of the first lens unit L1 and the second lens unit L2 becomes strong, and the amount of movement of each lens unit to ensure a predetermined zoom ratio decreases. Although advantageous for downsizing the entire system, correction of various aberrations such as astigmatism and coma becomes difficult due to the strong power of the first lens unit L1 and the second lens unit L2.

If the distance D23W increases beyond the upper limit of conditional expression (2), focusing on the closest object at the wide-angle end when focusing with the third lens unit L3 becomes easy, but the overall length of the lens becomes compact because the total lens length increases. Becomes difficult.

If the distance D23W is reduced beyond the lower limit of conditional expression (2), it is difficult to focus on the closest object at the wide-angle end with only the third lens unit L3. For example, the first lens unit L1 is used for focusing. This is not good because the mechanical structure becomes complicated, and the effective diameter of the first lens unit increases due to the movement of the first lens unit L1.

If the lower limit of conditional expression (3) is exceeded, the variable magnification sharing of the second lens unit L2 will be insufficient, making it difficult to achieve a zoom ratio exceeding 4, and the amount of movement of the third lens unit L3 during zooming will be large. It is not good because the total length is enlarged.

If the upper limit of conditional expression (3) is exceeded, the variable magnification share of the second lens unit L2 becomes too large. Therefore, the number of lenses constituting the second lens unit L2 is increased, and aberrations in the second lens unit L2 are increased. This is not desirable because the entire length of the second lens unit L2 becomes long.

If the lower limit value of conditional expression (4) is exceeded, the power of each lens constituting the first lens unit L1 for obtaining a predetermined zoom ratio must be increased, so the curvature of the lens surface, particularly the lens surface on the image side. In order to obtain a predetermined zoom ratio by reducing the curvature, the number of lenses in the first lens unit L1 increases, and the entire system becomes larger. Therefore, it is not preferable.

If the lower limit of conditional expression (5) is exceeded, the number of lenses constituting the second lens unit L2 must be increased or the thickness of the negative lens must be increased in order to obtain a predetermined zoom ratio. It becomes difficult to make compact.

If the power of the second lens unit L2 becomes weaker than the upper limit of the conditional expression (6), the movement amount of the second lens unit L2 increases to secure a predetermined zoom ratio, which is disadvantageous for downsizing.

If the power of the third lens unit L3 is increased beyond the upper limit, the number of lenses must be increased in order to correct astigmatism, making it difficult to make the entire system compact.

When the power of the second lens unit L2 increases beyond the lower limit of conditional expression (6), the number of the second lens unit L2 must be increased in order to correct astigmatism and coma, and the entire system is compact. It becomes difficult.

Exceeding the upper limit of conditional expression (7) is not preferable because the exit pupil distance becomes closer to the image plane and the telecentricity becomes worse.

Further, when the power of the third lens unit L3 is increased beyond the lower limit of the conditional expression (7), the telecentricity is improved, but the astigmatism is increased, and it is difficult to correct this.

In order to correct aberrations and to reduce the size of the entire lens system, the numerical ranges of the conditional expressions described above are preferably set as follows.

0.6 <D23 w /fw<1.1 (2a)
3.9 <(β2 t · β3 w ) / (β2 w · β3 t ) <5.1 (3a)
1.90 <n1a (4a)
1.90 <n2b (5a)
2.0 <f3 / f2 <2.4 (6a)
5.3 <f3 / f w <6.35 ···· (7a)
To satisfy the following conditions.

In each embodiment, by setting each element as described above, it is particularly suitable for an imaging system using a solid-state imaging device, is compact with a small number of constituent lenses, and particularly suitable for a retractable type, with a zoom ratio of 4 to 4 A zoom lens having an excellent optical performance of about 6 times can be achieved.

Further, according to each embodiment, by effectively introducing an aspheric surface into the first lens unit L1, in particular, by appropriately setting the refractive powers of the first lens unit L1 and the second lens unit L2, off-axis. Various aberrations, particularly astigmatism, distortion, and spherical aberration when the aperture ratio is increased can be effectively corrected.

In each of the above embodiments, instead of moving the three lens groups during zooming, the two lens groups (for example, the first and second lens groups,
Alternatively, the present invention can also be applied to a zoom type in which the first and third lens groups or the second and third lens groups) are moved.

Further, even if a lens unit having a small refractive power is added to the object side of the first lens unit L1 and / or the image side of the third lens unit L3, the effect obtained by the present invention remains unchanged.

Next, numerical examples of the present invention will be shown. In each numerical example, i indicates the order of the surfaces from the object side, Ri is the radius of curvature of the lens surface, Di is the distance between the i-th surface and the (i + 1) -th surface, Ni
, Νi respectively indicate the refractive index and Abbe number with respect to the d-line.

The two surfaces closest to the image side are glass materials such as face plates.

The aspherical shape is such that the light traveling direction is positive, x is the amount of displacement from the surface vertex in the optical axis direction, h
Is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial radius of curvature, k is the conic constant, and B to E are aspherical coefficients,
x = (h ² / R) / [1+ {1− (1 + k) (h / R) ² } ^1/2 ]
+ Bh ⁴ + Ch ⁶ + Dh ⁸ + Eh ¹⁰
It is expressed by the following formula.

“E-0X” means “× 10 ^−x ”. f represents a focal length, Fno represents an F number, and ω represents a half angle of view. Table 1 shows the relationship between the above-described conditional expressions and numerical examples.

Numerical example 1

f = 4.69-21.60 Fno = 2.56-5.97 2ω = 65.5 ° -15.9 °

R 1 = 28.278 D 1 = 1.80 N 1 = 1.882997 ν 1 = 40.8
R 2 = 5.123 D 2 = 2.84
R 3 = 9.485 D 3 = 1.75 N 2 = 1.922860 ν 2 = 18.9
R 4 = 16.168 D 4 = Variable
R 5 = Aperture D 5 = 0.40
R 6 = 13.007 D 6 = 1.50 N 3 = 1.693501 ν 3 = 53.2
R 7 = 690.521 D 7 = 0.10
R 8 = 6.185 D 8 = 2.25 N 4 = 1.696797 ν 4 = 55.5
R 9 = -18.336 D 9 = 1.60 N 5 = 1.901355 ν 5 = 31.6
R10 = 5.092 D10 = 0.81
R11 = 23.853 D11 = 1.30 N 6 = 1.719995 ν 6 = 50.2
R12 = -17.457 D12 = variable
R13 = 18.330 D13 = 1.60 N 7 = 1.487490 ν 7 = 70.2
R14 = -36.938 D14 = variable
R15 = ∞ D15 = 1.00 N 8 = 1.516330 ν 8 = 64.1
R16 = ∞

Focal length 4.69 12.90 21.60
Variable interval
D 4 20.33 5.16 1.80
D12 4.02 15.03 26.52
D14 4.33 4.08 3.36

Aspheric coefficient
R2 k = -1.57269e + 00 B = 9.31352e-04 C = -9.32116e-07 D = 1.10249e-08
E = 3.97985e-10
R8 k = -1.77870e-01 B = 5.38565e-05 C = 2.46566e-06

Numerical example 2

f = 4.50〜24.35 Fno = 2.74〜7.00 2ω = 67.7 ° 〜14.1 °

R 1 = 28.104 D 1 = 1.80 N 1 = 1.882997 ν1 = 40.8
R 2 = 5.326 D 2 = 2.67
R 3 = 9.520 D 3 = 1.75 N 2 = 1.922860 ν 2 = 18.9
R 4 = 16.301 D 4 = Variable
R 5 = Aperture D 5 = 0.20
R 6 = 10.497 D 6 = 1.50 N 3 = 1.620411 ν 3 = 60.3
R 7 = 91.154 D 7 = 0.10
R 8 = 6.413 D 8 = 2.05 N 4 = 1.788001 ν 4 = 47.4
R 9 = -27.354 D 9 = 1.50 N 5 = 2.003300 ν 5 = 28.3
R10 = 5.137 D10 = 0.50
R11 = 24.649 D11 = 1.20 N 6 = 1.834000 ν 6 = 37.2
R12 = -22.165 D12 = variable
R13 = 15.118 D13 = 1.60 N 7 = 1.516330 ν 7 = 64.1
R14 = -112.010 D14 = variable
R15 = ∞ D15 = 1.00 N 8 = 1.516330 ν 8 = 64.1
R16 = ∞

Focal length 4.50 14.14 24.35
Variable interval
D 4 23.38 5.25 1.80
D12 3.95 16.12 28.69
D14 4.25 3.96 3.25

Aspheric coefficient
R2 k = -1.31424e + 00 B = 6.16883e-04 C = 3.16840e-06 D = 1.01182e-08
E = -3.58477e-10
R8 k = -2.76663e + 00 B = 1.25488e-03 C = -1.10959e-05 D = 3.02464e-07

Numerical Example 3

f = 4.29-25.30 Fno = 2.50-6.90 2ω = 70.2 ° -13.6 °

R 1 = 33.847 D 1 = 1.80 N 1 = 1.882997 ν 1 = 40.8
R 2 = 5.319 D 2 = 2.49
R 3 = 9.526 D 3 = 1.75 N 2 = 1.922860 ν 2 = 18.9
R 4 = 16.478 D 4 = Variable
R 5 = Aperture D 5 = 0.20
R 6 = 10.394 D 6 = 1.45 N 3 = 1.639999 ν 3 = 60.1
R 7 = 62.083 D 7 = 0.10
R 8 = 6.334 D 8 = 2.10 N 4 = 1.772499 ν 4 = 49.6
R 9 = -51.827 D 9 = 1.55 N 5 = 2.003300 ν 5 = 28.3
R10 = 5.096 D10 = 0.55
R11 = 22.577 D11 = 1.20 N 6 = 1.834000 ν 6 = 37.2
R12 = -21.511 D12 = variable
R13 = 12.440 D13 = 1.60 N 7 = 1.516330 ν 7 = 64.1
R14 = 110.419 D14 = variable
R15 = ∞ D15 = 1.00 N 8 = 1.516330 ν 8 = 64.1
R16 = ∞

Focal length 4.29 14.31 25.30
Variable interval
D 4 22.31 4.94 1.78
D12 3.54 16.87 30.62
D14 4.16 3.50 2.42

Aspheric coefficient
R1 k = 1.66792e + 01 B = 3.29890e-05 C = -3.75031e-06 D = 7.54949e-08
E = -8.64945e-10
R2 k = -1.28756e + 00 B = 6.38450e-04 C = 5.28748e-06 D = -1.07260e-07
E = 7.71211e-10
R8 k = -3.00310e + 00 B = 1.38557e-03 C = -1.77869e-05 D = 5.11304e-07

Numerical Example 4

f = 4.69〜21.60 Fno = 2.52〜5.97 2ω = 65.5 ° 〜15.9 °

R 1 = 27.781 D 1 = 1.80 N 1 = 1.882997 ν 1 = 40.8
R 2 = 5.112 D 2 = 2.87
R 3 = 9.459 D 3 = 1.75 N 2 = 1.922860 ν 2 = 18.9
R 4 = 16.081 D 4 = variable
R 5 = Aperture D 5 = 0.40
R 6 = 12.693 D 6 = 1.50 N 3 = 1.693501 ν 3 = 53.2
R 7 = 748.560 D 7 = 0.10
R 8 = 6.188 D 8 = 2.25 N 4 = 1.696797 ν 4 = 55.5
R 9 = -17.856 D 9 = 1.60 N 5 = 1.901355 ν 5 = 31.6
R10 = 5.062 D10 = 0.90
R11 = 24.749 D11 = 1.30 N 6 = 1.719995 ν 6 = 50.2
R12 = -17.554 D12 = variable
R13 = 20.052 D13 = 1.60 N 7 = 1.487490 ν 7 = 70.2
R14 = -32.668 D14 = variable
R15 = ∞ D15 = 1.00 N 8 = 1.516330 ν 8 = 64.1
R16 = ∞

Focal length 4.69 17.55 21.60
Variable interval
D 4 19.84 5.11 1.80
D12 3.00 14.28 26.27
D14 4.99 4.58 3.48

Aspheric coefficient
R2 k = -1.55604e + 00 B = 9.15097e-04 C = -5.65375e-08 D = 7.02344e-09
E = 2.63734e-10
R8 k = -2.86351e-01 B = 1.03856e-04 C = 4.26746e-06

Numerical Example 5

f = 4.69-21.60 Fno = 2.58-5.97 2ω = 65.5 ° -15.9 °

R 1 = 28.388 D 1 = 1.80 N 1 = 1.882997 ν 1 = 40.8
R 2 = 5.087 D 2 = 2.90
R 3 = 9.529 D 3 = 1.75 N 2 = 1.922860 ν 2 = 18.9
R 4 = 16.168 D 4 = Variable
R 5 = Aperture D 5 = 0.10
R 6 = 13.199 D 6 = 1.50 N 3 = 1.693501 ν 3 = 53.2
R 7 = 554.461 D 7 = 0.10
R 8 = 6.184 D 8 = 2.25 N 4 = 1.696797 ν 4 = 55.5
R 9 = -18.358 D 9 = 1.60 N 5 = 1.901355 ν 5 = 31.6
R10 = 5.115 D10 = 0.81
R11 = 22.733 D11 = 1.30 N 6 = 1.719995 ν 6 = 50.2
R12 = -16.955 D12 = variable
R13 = 16.884 D13 = 1.60 N 7 = 1.487490 ν 7 = 70.2
R14 = -49.680 D14 = variable
R15 = ∞ D15 = 1.00 N 8 = 1.516330 ν 8 = 64.1
R16 = ∞

Focal length 4.69 12.98 21.60
Variable interval
D 4 20.79 5.40 1.96
D12 5.06 15.84 26.79
D14 3.58 3.27 2.80

Aspheric coefficient
R2 k = -1.49618e + 00 B = 8.75196e-04 C = -3.59972e-07 D = 1.41022e-08
E = 3.46972e-10
R8 k = -4.33552e-01 B = 1.86343e-04 C = 5.39556e-06

Next, an embodiment of a digital still camera (imaging device) using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG.

In FIG. 21, reference numeral 20 denotes a camera body, 21 denotes a photographing optical system constituted by the zoom lens of the present invention, 22 denotes a CCD sensor or CMOS sensor incorporated in the camera body and receiving a subject image formed by the photographing optical system 21. A solid-state image pickup device (photoelectric conversion device) such as 23, a memory 23 for recording information corresponding to the subject image photoelectrically converted by the image pickup device 22, and a liquid crystal display panel 24 are formed on the solid-state image pickup device 22. This is a viewfinder for observing the subject image.

Thus, by applying the zoom lens of the present invention to an image pickup apparatus such as a digital still camera, a small image pickup apparatus having high optical performance is realized.

Optical cross-sectional view of the zoom lens of Example 1 Aberration diagram at the wide-angle end of the zoom lens of Example 1 Aberration diagram at the middle zoom position of the zoom lens of Example 1 Aberration diagram at the telephoto end of the zoom lens of Example 1 Optical sectional view of the zoom lens of Example 2 Aberration diagram at the wide-angle end of the zoom lens of Example 2 Aberration diagram at the intermediate zoom position of the zoom lens of Example 2 Aberration diagram at the telephoto end of the zoom lens of Example 2 Optical sectional view of the zoom lens of Example 3 Aberration diagram at the wide-angle end of the zoom lens of Example 3 Aberration diagram at the intermediate zoom position of the zoom lens of Example 3 Aberration diagram at the telephoto end of the zoom lens of Example 3 Optical sectional view of the zoom lens of Example 4 Aberration diagram at the wide-angle end of the zoom lens of Example 4 Aberration diagram at the intermediate zoom position of the zoom lens of Example 4 Aberration diagram at the telephoto end of the zoom lens of Example 4 Optical sectional view of the zoom lens of Example 5 Aberration diagram at the wide-angle end of the zoom lens in Example 5 Aberration diagram at the intermediate zoom position of the zoom lens of Example 5 Aberration diagram at the telephoto end of the zoom lens of Example 5 Schematic diagram of main parts of an imaging apparatus of the present invention

Explanation of symbols

L1 First lens group L2 Second lens group L3 Third lens group SP Aperture IP Image plane G Glass block d d line g g line ΔS Sagittal image plane ΔM Meridional image plane

Claims

In order from the object side to the image side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power and a positive third lens group refractive power, hand spacing of each lens group changes upon zooming in the zoom lens, Deruta2X the movement amount of the second lens group in zooming from the wide-angle end to the telephoto end, d23w the distance between the third lens group and the second lens group at the wide-angle end, the first lens group when the focal length of each of the f1 of the second lens group, f2, the focal length of the entire system at the wide angle end fw, the average value of the refractive index of the material of the lenses constituting the first lens group and n1a and,
1.7 <Δ2X / √ | f1 · f2 | <2.3
0.5 <D23w / fw <1.2
1.88 <n1a
A zoom lens that satisfies the following conditions:
In order from the object side to the image side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power and a positive third lens group refractive power, hand spacing of each lens group changes upon zooming in the zoom lens, the first lens group consists of two lenses, from the wide-angle end Δ2X the amount of movement of the second lens group during zooming to the telephoto end, the first lens group of the second lens group When the focal lengths are f1 and f2, respectively, and the average value of the refractive index of the materials of the lenses constituting the first lens group is n1a ,
1.7 <Δ2X / √ | f1 · f2 | <2.3
1.88 <n1a
A zoom lens that satisfies the following conditions:
In order from the object side to the image side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power and a positive third lens group refractive power, hand spacing of each lens group changes upon zooming in the zoom lens, Deruta2X the movement amount of the second lens group in zooming from the wide-angle end to the telephoto end, d23w the distance between the third lens group and the second lens group at the wide-angle end, the first lens group when the focal length of each of the f1 of the second lens group, f2, the focal length of the entire system at the wide angle end fw, the refractive index of the material of the negative lens constituting the second lens group and n2b and,
1.7 <Δ2X / √ | f1 · f2 | <2.3
0.5 <D23w / fw <1.2
1.85 <n2b
A zoom lens that satisfies the following conditions:
In order from the object side to the image side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power and a positive third lens group refractive power, hand spacing of each lens group changes upon zooming in the zoom lens, the first lens group consists of two lenses, from the wide-angle end Δ2X the amount of movement of the second lens group during zooming to the telephoto end, the first lens group of the second lens group When the focal lengths are f1 and f2, respectively, and the refractive index of the material of the negative lens constituting the second lens group is n2b ,
1.7 <Δ2X / √ | f1 · f2 | <2.3
1.85 <n2b
A zoom lens that satisfies the following conditions:
When the average value of the refractive index of the material of the lens constituting the first lens group is n1a,
1.88 <n1a
The zoom lens according to claim 3, wherein the following condition is satisfied.
When the imaging magnifications at the wide-angle end and the telephoto end of the second lens group are β2w and β2t, respectively, and the imaging magnifications at the wide-angle end and the telephoto end of the third lens group are β3w and β3t, respectively.
3.8 <(β2t · β3w) / (β2w · β3t) <5.2
The zoom lens according to claim 1 , wherein the following condition is satisfied.
During zooming from the wide-angle end to the telephoto end, the first lens group moves along a convex locus toward the image side, the second lens group moves toward the object side, and the third lens group moves toward the image side. The zoom lens according to claim 1 , wherein the zoom lens is a zoom lens.
The zoom lens according to any one of claims 1 to 7, wherein the first lens group includes a negative lens and a positive lens, and at least one surface of the negative lens has an aspherical shape.
Wherein the first lens group, a negative lens on the image side surface is concave outcomes Nisukasu shape comprises a positive lens on the object side surface is convex outcomes Nisukasu shape, the image side surface of the negative lens is aspherical The zoom lens according to claim 1 , wherein the zoom lens has a shape.
10. The zoom lens according to claim 1, wherein the second lens group includes a positive lens, a positive lens, a negative lens, and a positive lens in order from the object side to the image side.
The second lens group includes, in order from the object side to the image side, a positive lens having a convex surface on the object side, a positive lens having a convex shape on both lens surfaces, a negative lens having a concave shape on both lens surfaces, and a positive lens. The zoom lens according to claim 1 , wherein the zoom lens is a zoom lens.
When the focal length of the third lens group is f3,
1.9 <f3 / f2 <2.5
The zoom lens according to claim 1 , wherein the following condition is satisfied.
When the focal length of the third lens group is f3 and the focal length of the entire system at the wide angle end is fw ,
5.2 <f3 / fw <6.4
The zoom lens according to claim 1 , wherein the following condition is satisfied.
The zoom lens according to any one of claims 1 to 13, wherein the third lens group includes a single positive lens.
The zoom lens according to claim 1, wherein the third lens group is moved toward the object side to perform focusing from an object at infinity to an object at a short distance.
The zoom lens according to claim 1 , wherein an image is formed on a solid-state image sensor.
A zoom lens according to any one of claims 1 to 16, an imaging apparatus characterized by having a solid-state imaging device for receiving an image formed by the zoom lens.