JP4669294B2 - A zoom lens and an image pickup apparatus having the same - Google Patents

Description

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

Recently, a video camera using a solid-state imaging device, a digital still camera or the like, with the sophistication of the imaging apparatus (camera), the zoom lens of a large aperture ratio is obtained which encompasses a wide photographic angle in the optical system used therefor ing.

More of this type of camera, between the lens rearmost portion and an image pickup element, for positioning the various optical members such as a low-pass filter and a color correction filter, the optical system used therein, a relatively back focus long lens system There is required. In addition, if a camera using an image sensor for color images, in order to avoid color shading, is desired good telecentricity on the image side in the optical system used therein.

Conventionally, it consists of two lens groups of negative refractive power first lens group and positive refractive power second lens group, and performs zooming by changing both the lens interval, the 2-group zoom lens of a so-called short zoom type various proposals have been made. These short zoom type of optical system performs zooming by moving the second lens unit having a positive refractive power, varies with zooming by moving the first lens unit having a negative refractive power It is performed to compensate for image position. In the lens arrangement consisting of the two lens groups, the zoom ratio is about 2 times.

While having more than twice the zoom ratio, to put together the entire lens into a compact shape, arranged third lens unit having a negative or positive refractive power on the image side of the two-unit zoom lens, aiming a high zoom ratio and a so-called three-unit zoom lens has also been proposed (e.g. Patent documents 1 and 2).

Also has a long back focus as three-group zoom lens, and is also known zoom lens system satisfying the telecentric characteristic (for example, Patent Documents 3 and 4).

Further, negative, positive, in the three-unit zoom lens composed of lens unit having positive refractive power, upon zooming the first lens unit having a negative refractive power, and fixed, and the positive refractive second lens unit having a positive refractive power third moving the lens group zoom lens that performs zooming force is known (e.g. Patent Document 5).

Further, negative, positive, in the three-unit zoom lens composed of lens unit having positive refractive power, a second lens group positive lens, a positive lens, and a negative lens, zoom lens constituted of a positive lens is known ( Patent Document 6-13).

Further, negative, positive, the positive refractive power of the lens three-unit zoom lens composed of a group, the zoom lens of a zoom ratio of 3 or more high zoom ratio is known (e.g. Patent Document 14-23).
Kokoku 7-3507 Patent Publication No. Kokoku 6-40170 Patent Publication No. JP-A-63-135913 JP JP-7-261083 discloses JP-3-288113 discloses JP-9-258103 discloses JP-11-52246 discloses JP 11-174322 discloses JP 11-174322 discloses JP 11-194274 discloses Patent No. 3466385 JP 2002-23053 JP JP 2002-196240 JP JP-4-217219 discloses JP 10-039214 discloses Patent flat 10-213745 JP JP 11-119101 discloses JP 11-174322 discloses JP 2001-42218 JP Patent 2002-3655545 No. JP 2002-267930 JP JP 2003-156686 JP Patent No. 2895843

35mm film zoom lens that is designed for photographs, for use in imaging apparatus using a solid-state imaging device, the back focus is too long, and because poor telecentricity, the image pickup apparatus using a solid state imaging device it is difficult to use as it is.

On the other hand, a high zoom ratio of compact zoom lens of the camera in order to achieve both (Kobaika), to reduce the distance between the lens units at the time of non-shooting to different intervals between the photographing state, the projection amount of the lens from the camera body the less the so-called retractable zoom lens is widely used.

In general, the number of lenses in each lens unit constituting the zoom lens is large, it may increase the length on the optical axis of each lens unit, also the total lens length becomes long and the amount of movement is large in the zooming and focusing of the lens units Therefore, the desired collapsed length no longer be achieved, to use the retractable zoom lens becomes difficult.

This tendency becomes more remarkable as the zoom ratio of the zoom lens becomes large.

The present invention, number of lens elements is relatively small, and at a desired angle at the wide angle end, and an object thereof is to provide a image pickup apparatus having a zoom lens and it was realized the desired zoom ratio.

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 and n1a,
1.7 <Δ2X / √ | f1 · f2 | <2.3
0.5 <D23w / fw <1.2
1.88 <n1a
It is characterized by satisfying the following condition.

In addition, 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, 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 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 condition.

In addition, 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, 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 and n2b,
1.7 <Δ2X / √ | f1 · f2 | <2.3
0.5 <D23w / fw <1.2
1.85 <n2b
It is characterized by satisfying the following condition.

In addition, 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, 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 condition.

According to the present invention, number of lens elements is relatively small, a wide field angle and a high zoom ratio zoom lens is obtained.

Hereinafter, a description will be given of an embodiment of an image pickup apparatus having a zoom lens and its invention.

Figure 1 is a lens cross sectional view at the wide-angle end (short focal length end) of the zoom lens of Embodiment 1 of the present invention, FIGS. 2, 3, 4, respectively, at the wide angle end of the zoom lens according to the first embodiment, an intermediate zoom position , and the telephoto end (long focal length end). Example 1 has a zoom ratio of 4.6, an aperture ratio from 2.6 to 6.0 approximately zoom lens.

Figure 5 is a lens cross sectional view at the wide-angle end of the zoom lens of Embodiment 2 of the present invention, FIGS. 6, 7, 8, respectively, at the wide angle end of Embodiment 2 zoom lens, an intermediate zoom position, the telephoto end it is. Example 2 has a zoom ratio of 5.4, an aperture ratio from 2.7 to 7.0 approximately zoom lens.

Figure 9 is a lens cross sectional view at the wide-angle end of the zoom lens of Embodiment 3 of the present invention, FIGS. 10, 11 and 12 respectively, at the wide angle end the zoom lens according to the third embodiment, the intermediate zoom position, the telephoto end it is. Example 3 has a zoom ratio of 5.9 and an aperture ratio of 2.5 to 6.9 about the zoom lens.

Figure 13 is a lens cross sectional view at the wide-angle end of the zoom lens of Embodiment 4 of the present invention, FIGS. 14, 15 and 16 respectively, at the wide angle end of the zoom lens according to the fourth embodiment, an intermediate zoom position, the telephoto end it is. Example 4 has a zoom ratio of 4.6 and an aperture ratio 2.5 to 6.0 about the zoom lens.

Figure 17 is a lens cross section at a wide angle end according to Embodiment 5 of the zoom lens of the present invention, FIGS. 18, 19, 20, respectively, at the wide angle end Example 5 of the zoom lens, an intermediate zoom position, the telephoto end it is. Example 5 has a zoom ratio of 4.6 and an aperture ratio 2.5 to 6.0 about the zoom lens.

Figure 21 is a digital still camera (image pickup apparatus) main part schematic diagram including the zoom lens of the present invention.

The zoom lens of each embodiment is a photographing lens system used in an image pickup apparatus, the lens sectional view, the left side is the object side (front side), the right side is the image side (rear).

1, 5, 9, 13, in the lens sectional view of FIG. 17, L1 denotes a first lens unit having a negative refractive power (optical power = reciprocal of focal length), L2 is a positive refractive power first second lens group, L3 denotes a third lens unit having positive refractive power, SP denotes an aperture stop, which is disposed on the object side of the second lens unit L2.

G denotes an optical block corresponding to an optical filter, a faceplate, a crystal low-pass filter, an infrared cut filter, or the like. IP denotes an image plane, when used as a photographic optical system of a video camera or a digital still camera is sensitive surface corresponding to the imaging surface of the solid-state imaging element such as a CCD sensor or a CMOS sensor (photoelectric conversion element) is placed.

In the aberration diagrams, d, g d-line and the g-line, .DELTA.M, [Delta] S denote a meridional image plane and a sagittal image plane, the magnification chromatic aberration is represented by the g-line.

Incidentally, the wide-angle end and the telephoto end in the following embodiments mean zoom positions when the zoom lens group (second lens unit L2) is located at both ends in the mechanism on the optical axis on the movable range.

In the zoom lens of each embodiment, during zooming from the wide-angle end to the telephoto end, the first lens unit L1 is substantially reciprocally moved with a locus convex toward the image side, the second lens unit L2 is moved toward the object side, and the third lens unit L3 moves to the image side.

The zoom lens of each embodiment performs main magnification by the movement of the second lens unit L2, the image associated with zooming by moving toward the image side direction of the reciprocating movement and the third lens unit L3 in the first lens unit L1 movement is corrected for.

Next, detailed characteristics of the lens configuration.

The first lens unit L1 includes, in order from the object side to the image side, composed of two lenses of a negative lens G11 having a meniscus shape with a convex surface facing the object side, a positive meniscus lens having a convex surface directed toward the object side G12 doing.

The first lens unit L1, has a role of pupil imaging to SP central aperture off-axis principal ray, off-axis aberrations for refraction of the off-axis principal ray is large, particularly in the wide-angle side, particularly non easy astigmatism and distortion aberration occurs.

Therefore, in each embodiment, as with ordinary wide-angle lens, and the lens configuration of a negative lens and a positive lens that increases the lens diameter on the most object side is suppressed.

Then, by an aspheric shape which negative refractive power becomes weaker lens surface on the image side of the negative lens G11 at the lens periphery, while correcting astigmatism and distortion aberration in good balance, a small number of lenses to say two in constitute a first lens group L1, thereby achieving a compactness of the entire lens.

The respective lenses constituting the first lens unit L1, a lens shape close to a concentric spherical surface aperture stop SP and the optical axis in order to suppress the occurrence of off-axis aberration caused by refraction of off-axis principal ray is centered point of intersection It is set to.

The second lens unit L2 includes, in order from the object side to the image side, a positive lens of plane-convex shape on the object side G21, a positive lens G22 and the both lens surfaces of both lens surfaces is a convex shape and a negative lens G23 concave bonding the cemented lens, and a positive lens G24.

The second lens unit L2, arranged between the positive lens G21 positive lens G22 on the object side, a first lens unit L1 to reduce the angle of refraction of the off-axis principal ray emitted, such as off-axis aberrations are not generated lens It has a shape.

The positive lens G21 is a height higher lens through the most axial ray are mainly spherical aberration, lenses involved in correction of coma. Therefore, in each example, place the positive lens G21 and the positive lens G22, the spherical aberration by gradually refracting a light beam, it is well correct coma aberration.

Then, the surface on the image side of the negative lens G23 constructed by cementing the positive lens G22, by a concave shape, to cancel the aberration generated a positive lens G21 at the positive lens G22.

The third lens unit L3, the surface of at least one object side and a positive lens G31 having a convex shape. In each embodiment, it consists of a single positive lens.

The third lens unit L3, shares the increase of the refractive power of each lens due to the size of the imaging device, first, by reducing the refractive power of the composed short zoom system in the second lens group L1, L2 We have achieved good optical performance suppressing generation of aberration in each lens constituting especially the first lens unit L1. Also it has been achieved by particularly to have a role of a field lens with telecentric imaging of the imaging apparatus necessary for the image side in the third lens unit L3 which uses a solid-state image pickup element or the like.

Here, sk back focus', the focal length of the third lens unit L3 f3, if the imaging magnification of the third lens unit L3 and .beta.3,
sk '= f3 (1-β3)
It is made up of the relationship.

However,
0 <β3 <1.0
It is.

Here, will be when moving the third lens unit L3 during zooming to the telephoto end from the wide-angle end to the image side back focus sk 'decreases, the imaging magnification β3 of the third lens unit L3 at the telephoto side zoom region in increases. Then, eventually it will be shared zooming by the third lens unit L3, the moving amount of the second lens unit L2 is reduced, which contributes to the miniaturization of the lens system in order to save space therefor.

When the shooting to a close object from infinity using the zoom lens of each embodiment, although the first lens unit L1 can be obtained good performance by moving toward the object side, more preferably It is it is better to perform the third lens unit L3 is moved to the object side focus.

This most first lens unit L1 disposed on the object side occurs when moving in focusing, increase in the front lens diameter, the load of the actuator due to lens weight moves the heaviest first lens unit L1 This is because it is possible to prevent an increase. Also, by not moving the first lens unit L1 for focusing, and simply cooperate it can be moved during zooming from the first lens unit L1 and the second lens group L2 by a cam or the like, the mechanical structure the simplification and accuracy improvement can be achieved.

When performing the focusing by the third lens unit L3, by moving the third lens unit L3 on the image side during zooming from the wide-angle end to the telephoto end, the third lens group with a large telephoto end the focusing movement amount since the position of L3 can be disposed on the image side than the wide angle end, it is possible to minimize the moving amount of the sum of the third lens unit L3 which is required in zooming and focusing, a compact lens system reduction is facilitated.

As described above, by the lens configuration of each lens group to achieve both the desired refractive power arrangement and the aberration correction, while maintaining excellent optical performance, compactness of the entire lens system, a high zoom ratio, and collapsed It has achieved a shortening of the length.

In the zoom lens of each embodiment, in order to obtain a good optical performance, or to achieve entire lens system compact is so as to satisfy at least one or more of the following conditions. Thus, to obtain the effect corresponding to the conditional expressions.

Movement amount Δ2X of the second lens unit L2 during zooming from the wide-angle end to the telephoto end (the sign of the movement amount Δ2X is in the movement toward the object side positive and negative vice versa), the second lens group at the wide-angle end L2 and D23W the distance between the third lens unit L4, the first lens unit L1, the second lens unit L2, the focal length of the third lens unit L3 sequentially f1, f2, f3, the focal length of the entire system at the wide-angle end the fw, and the wide-angle end of the second lens group L2, .beta.2w each imaging magnification at the telephoto end,? 2t, and the wide-angle end of the third lens unit L3,? 3w each imaging magnification at the telephoto end, [beta] 3t, the n1a an average value of the refractive index of the material of the lenses constituting the first lens unit L1, the second lens unit L2 includes a negative lens, when the n2b a material having a refractive index of the negative lens,

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)
It satisfies the following condition.

If below the lower limit of condition (1) is moving amount Δ2X of the second lens unit L2 during zooming is reduced, the first lens unit L1 power becomes loose of the second lens group L2, to ensure a predetermined zoom ratio the amount of movement of each lens group is increased, the entire system compact it becomes difficult to.

Further, if the upper limit value of conditional expression (1), since the first lens unit L1 and the second power of the lens unit L2 becomes too strong, the amount of movement of each lens unit for securing a predetermined zoom ratio decreases there is advantageous for downsizing of the entire system, but the astigmatism, the correction of various aberrations such as coma becomes difficult by the first lens unit L1 power of the second lens unit L2 increases.

If the interval D23W beyond the upper limit of condition (2) becomes large, compact entire system for While focusing on a close object becomes easy to increase the total lens length at the wide-angle end when focusing by the third lens unit L3 it becomes difficult.

If the interval D23W beyond the lower limit of condition (2) is reduced, to perform the focusing on the close object only by the third lens unit L3 becomes difficult at the wide-angle end, for example, further to the first lens unit L1 of focusing will be moved, mechanical structure is complicated, also, not good effective diameter of the first lens group by the movement of the first lens unit L1 comes increased.

If the lower limit of condition (3), zooming share of the second lens unit L2 becomes insufficient, it becomes difficult to realize a zoom ratio greater than 4, and a large amount of movement of the third lens unit L3 during zooming now, it is not good because the entire length come to expand.

Also, since the conditional expression (3) magnification sharing exceeds the upper limit second lens unit L2 is too large, increasing the number of lenses constituting the second lens unit L2, aberrations in the second lens unit L2 must to the load distribution is not preferable total length of the second lens unit L2 is long.

If the lower limit of Condition (4), the predetermined song lens surface since it is necessary to increase the power of each lens constituting the first lens unit L1 for obtaining a zoom ratios, especially the image-side lens surface the radius of curvature is small, it lens molding becomes difficult, also loosely curvature lenses in the first lens unit L1 is increased in order to obtain the predetermined zoom ratio, the entire system comes in size undesirable since.

Further, if the lower limit value of conditional expression (5), of the entire system because it must increase the number of lenses of the second lens unit L2, or the thickness of the negative lens increases in order to obtain the predetermined zoom ratio compact becomes difficult.

If the condition second power of the lens group L2 exceeds the upper limit of the condition (6) is weakened, the amount of movement of the second lens unit L2 increases in order to ensure a predetermined zoom ratio, which is disadvantageous for downsizing.

Further, the entire system compact without must not increase the number of lenses in order to correct the astigmatism if power increases in the third lens unit L3 exceeds the upper limit becomes difficult.

If the condition second lens unit L2 of power beyond the lower limit of the expression (6) becomes strong, astigmatism, compact the whole system must take into increasing the number of the second lens unit L2 to correct coma reduction becomes difficult.

If the upper limit value of conditional expression (7), the exit pupil distance becomes close from the image plane is not preferable because the telecentricity is poor.

Further, when the third power of the lens unit L3 than the lower limit of the conditional expression (7) becomes strong, but telecentricity becomes better and astigmatism increases, it becomes difficult to correct this.

Aberration correction, and more preferably for miniaturization of the entire lens system, may be set as follows the numerical range of the conditional expressions described above.

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)
It is to satisfy the following condition.

Each embodiment by setting each element as described above, in particular, suitable for photographic system using a solid-number of lens elements is at least compact, particularly suitable for collapsible zoom ratio is 4 a zoom lens having excellent optical performance approximately six times can be achieved.

Further, by introducing effectively non-spherical during the first lens unit L1 according to the embodiments, off-axis by particularly appropriately set the refractive power of the first lens unit L1 and the second lens unit L2 aberrations effectively performed especially correction of spherical aberration when the astigmatism, distortion, and a large aperture ratio.

The above in each embodiment, instead of moving the three lens groups during zooming, two lens groups so that the distance between the lens units are changed (e.g., the first and second lens group,
Or the first and can be applied to the third lens group or the second zoom type moving the third lens group).

Also, there is no change in the effect obtained by also present invention by adding a small lens group refractive power on the image side of the object side or / and the third lens unit L3 in the first lens unit L1.

Next, numerical examples of the present invention. In each numerical example, i denotes an order of a surface from the object side, the radius of curvature of Ri lens surface, Di is the distance between the i-th surface and the (i + 1) th surface, Ni
, .Nu.i the refractive index relative to the d line, respectively, the Abbe number.

The two surfaces nearest to the image side are a glass material such as a face plate.

The non-spherical shape, the amount of displacement of the traveling direction of light is positive, x from the surface vertex in the optical axis direction, h
The direction perpendicular to the optical axis of the height from the optical axis, R a paraxial curvature radius, k a conic constant, when the aspherical coefficients B to E,
^{x = (h 2 / R)} / [1+ {1- (1 + k) (h / R) 2} 1/2]
^{+ Bh 4 + Ch 6 + Dh} 8 + Eh 10
Made are represented by formula.

The "e-0X" means "× ^{10 -x".} f represents the focal length, Fno represents the F-number, omega denotes a half angle of view. The Table 1 shows the relationship between the numerical examples and the conditional expressions described above.

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


Aspherical coefficients
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


Aspherical coefficients
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


Aspherical coefficients
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


Aspherical coefficients
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 = diaphragm 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

Aspherical coefficients
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

The embodiment of a digital still camera (image pickup apparatus) using the zoom lens of the present invention as a photographic optical system will be described with reference to FIG. 21.

In Figure 21, 20 denotes a camera body, 21 is a photographing optical system constituted by the zoom lens of the present invention, 22 is incorporated in the camera body, CCD sensor or a CMOS sensor for receiving an object image formed by the imaging optical system 21 the solid-state imaging device and the like (photoelectric conversion element), 23 a memory for recording information corresponding to the object image photoelectrically converted by the imaging device 22, 24 includes a liquid crystal display panel or the like, is formed on the solid-state imaging device 22 and a finder for observing the subject image.

By applying the zoom lens of the present invention to an image pickup apparatus such as digital still cameras, and realize an imaging apparatus having a small size and high optical performance.

Optical sectional view of a zoom lens of Embodiment 1 Aberration diagram at the wide angle end of the zoom lens of Embodiment 1 Aberration diagrams at the intermediate zoom position of the zoom lens of Example 1 Aberration diagram in a telephoto end of the zoom lens of Embodiment 1 Optical sectional view of a zoom lens of Embodiment 2 Aberration diagram at the wide angle end of the zoom lens of Embodiment 2 Aberration diagrams at the intermediate zoom position of the zoom lens of Example 2 Aberration diagram in a telephoto end of the zoom lens of Embodiment 2 Optical sectional view of a zoom lens of Example 3 Aberration diagram at the wide angle end of the zoom lens in Example 3 Aberration diagrams at the intermediate zoom position of the zoom lens of Example 3 Aberration diagram in a telephoto end of the zoom lens in Example 3 Optical sectional view of a zoom lens of Example 4 Aberration diagram at the wide angle end of the zoom lens in Example 4 Aberration diagrams at the intermediate zoom position of the zoom lens of Example 4 Aberration diagram in a telephoto end of the zoom lens in Example 4 Optical sectional view of a zoom lens of Example 5 Aberration diagram at the wide angle end of the zoom lens in Example 5 Aberration diagrams at the intermediate zoom position of the zoom lens of Example 5 Aberration diagram in a telephoto end of the zoom lens in Example 5 Main part schematic diagram of an image pickup apparatus of the present invention

DESCRIPTION OF SYMBOLS

L1 first lens group L2 second lens unit L3 third lens group SP diaphragm IP image plane G glass block d d line g g-ray ΔS sagittal image plane ΔM meridional image plane

Claims (17)

1. 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
   Zoom lens satisfies the following condition.
2. 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 length, each f1, f2, the mean 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
   Zoom lens satisfies the following condition.
3. 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
   Zoom lens satisfies the following condition.
4. 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 the focal length of each 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
   Zoom lens satisfies the following condition.
5. When the n1a the average value of the refractive index of the material of the lenses constituting the first lens group,
   1.88 <n1a
   The zoom lens according to claim 3 or 4, characterized by satisfying the following condition.
6. The second lens group of each imaging magnification at the wide angle end and the telephoto end .beta.2w,? 2t, the third lens group each β3w the imaging magnification at the wide angle end and the telephoto end, when the [beta] 3t,
   3.8 <(β2t · β3w) / (β2w · β3t) <5.2
   The zoom lens according to any one of claims 1 to 5, characterized by satisfying the following condition.
7. During zooming from the wide-angle end to the telephoto end, the first lens unit moves with a locus convex toward the image side, the second lens unit moves toward the object side, the third lens unit moves toward the image side the zoom lens according to any one of claims 1 to 6, characterized in that.
8. Wherein the first lens group and a negative lens and a positive lens, at least one surface the zoom lens according to any one of claims 1 to 7, characterized in that an aspheric shape of the negative lens.
9. 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 any one of claims 1 to 8, characterized in that a shape.
10. The second lens group includes, in order from the object side to the image side, a positive lens, a positive lens, a negative lens, a zoom lens according to any one of claims 1 to 9, characterized in that a positive lens.
11. The second lens group includes, in order from the object side to the image side, a positive lens surface on the object side convex positive lens, both lens surfaces concave negative lens of both lens surfaces is convex, and a positive lens the zoom lens according to any one of claims 1 to 10, characterized in that.
12. When the focal length of the third lens group and f3,
    1.9 <f3 / f2 <2.5
    The zoom lens according to any one of claims 1 to 11, characterized by satisfying the following condition.
13. When the focal length of the third lens group f3, the focal length of the entire system at the wide angle end and fw,
    5.2 <f3 / fw <6.4
    The zoom lens according to any one of claims 1 to 12, characterized by satisfying the following condition.
14. The third lens group zoom lens according to any one of claims 1 to 13, characterized in that consists of a single positive lens.
15. The zoom lens according to any one of claims 1 to 14, wherein the performing the focusing on the close range object the third lens group is moved toward the object side from infinity.
16. The zoom lens according to any one of claims 1 to 15 and forming an image on a solid-state image device.
17. 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.

Images