JPH10206718A - Zoom lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a zoom lens in which the effective diameter of a 1st lens group is made small and which has high variable power ratio and high close-up photographing magnification by adopting a double focus system where a rear focus system and a front focus system are concurrently used. SOLUTION: This zoom lens is constituted of the 1st lens group G1 having positive refractive power, a 2nd lens group G2 moving for the purpose of variable power and having negative refractive power, a 3rd lens group G3 moving for the purpose of the variable power and having the positive refractive power, a 4th lens group G4 having the negative refractive power and a 5th lens group G5 having the positive refractive power, which are arranged in order from an object side on an optical axis. At least one lens group out of the 3rd lens group G3 to the 5th lens group G5 is moved on the optical axis so as to correct an image point position, and the 1st lens group G1 is manually moved on the optical axis so as to perform manual focusing, then at least one lens group out of the 3rd lens group G3 to the 5th lens group G5 is automatically moved on the optical axis so as to perform automatic focusing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens, and more particularly to a zoom lens suitable for a camcorder using a solid-state imaging device, a small micro camera, and the like.

[0002]

2. Description of the Related Art Conventionally, there has been a demand for a small zoom lens having a high zoom ratio and high optical performance from a wide angle range to a telephoto range for a photographic camera or a video camera. For this reason, there have been provided five-group type zoom lenses arranged in the order of positive, negative, positive, negative, and positive from the object side.

In such a zoom lens, if the first lens group closest to the object side is moved on the optical axis to perform focus adjustment, that is, a front focus type, a second lens group is required to secure a peripheral light amount. A large effective diameter is required for one lens group, and there is a problem that the diameter of the first lens group is increased. For this reason, for example, Japanese Unexamined Patent Application Publication No.
As disclosed in JP-A-5967, JP-A-7-151972, JP-A-8-5913, etc., a rear focus type zoom lens has been proposed.

[0004]

However, in the case of the rear focus type, since there is a member that restricts the movement of the focus lens group such as another lens group, the movement for focus adjustment is restricted. The conventional rear focus type zoom lens has a low close-up shooting magnification. For example, in the zoom lens disclosed in the above-mentioned publication, the close-up photographing magnification is only about β = −0.1 due to the restriction of the movement range of the lens group for focus adjustment.

Further, in such a conventional zoom lens, the refractive power of the second lens group is increased in order to obtain a high zoom ratio, and in general, distortion at the wide-angle end due to zooming increases. ing. Furthermore, since the refracting power of the second lens group is much stronger than that of the first lens group, moving the first lens group to the object side on the optical axis and using it for front focusing requires a large lens effective diameter. There was a problem that it was difficult.

Japanese Patent Application Laid-Open No. 58-129404 discloses a five-lens group arranged in the order of positive, negative, positive, positive, and positive. The first lens group is manually moved to perform manual focus adjustment. There is disclosed a zoom lens in which a lens group is automatically moved to perform automatic focus adjustment. Since the objective of this zoom lens is to make it compact when stored, zooming is performed by the first lens group and the fourth lens group, and focus adjustment is performed by the first and fifth lens groups. ing. In the case of this zoom lens, since the first lens group is used for zooming, there is a problem that its effective diameter is large, the optical performance is not sufficient, the zoom ratio is small, and close-up shooting is performed. The problem is that the area is not very large.

As described above, in the rear focus type using any one of the third and subsequent lens units, not only the effective diameter of the first lens unit is reduced, but also the amount of movement at the time of focusing is small, and the entire unit is small. There is an advantage that can be made. However, since a member that restricts movement, such as another lens group, is nearby, the amount of movement for focus adjustment is restricted, and there is a disadvantage that the focusable range is narrow. On the other hand, in the case of the front focus type using the first lens group, the moving range is not limited and has a wide focus range from infinity to a short distance, but the effective diameter of the first lens group is increased in order to secure a peripheral light amount. However, there is a disadvantage that downsizing is difficult.

In view of the above advantages and disadvantages, the present invention employs a double focus system which uses both a rear focus system and a front focus system, and can reduce the effective diameter of the first lens unit and achieve a high zoom ratio. And to provide a zoom lens having a high close-up shooting magnification.

[0009]

In order to achieve the above object, a zoom lens according to the present invention comprises a first lens group having a positive refractive power and arranged in order from the object side on an optical axis;
A second lens group movable for zooming and having a negative refractive power; a third lens group movable for zooming and having a positive refractive power; a fourth lens group having a negative refractive power And a fifth lens group having a positive refractive power. Then, at least one of the third to fifth lens groups is moved on the optical axis to correct the image point position, and the first lens group is manually moved on the optical axis to perform manual focus adjustment. And at least one of the third to fifth lens groups is automatically moved on the optical axis to perform automatic focus adjustment.

As described above, when focus adjustment is performed by moving at least one lens group after the third lens group on the optical axis, the amount of peripheral light at the wide-angle end due to zooming increases, and the front lens group in the first lens group increases. It is possible to reduce a decrease in the amount of peripheral light due to focusing. For this reason, the present invention employs a double focus system in which the first lens group is manually moved and at least one lens group after the third lens group is automatically moved to perform focusing, and the close-up magnification is increased. At the same time, the effective diameter of the first lens group can be reduced. That is, in the present invention, the manual front focus and the automatic rear focus are combined to compensate for the drawbacks of both methods and to take advantage of the advantages.

In manual focusing, since the first lens group moves on the optical axis, there is an advantage that the focus can be adjusted with the same extension amount regardless of the magnification. Further, at the time of automatic focusing, at least one lens group after the third lens group different from the first lens group moves on the optical axis to perform focusing.
Both manual and automatic focus adjustment can be performed without mechanical interference with each other. For this reason, the effective diameter of the first lens group can be made smaller than that of a front focus only zoom lens, and the focusable range is wider than that of a rear focus only zoom lens. A high zoom lens can be realized.

In the zoom lens of the present invention, the magnification β2 carried by the second lens group in the entire zooming range, the magnification β3 carried by the third lens group in the entire zooming range, and the fourth lens group in the entire zooming range. Is satisfied by any of the zoom conditions within the entire zoom range.
It is preferable to set lens parameters so as to satisfy (3). These conditional expressions are conditional expressions that enable both front focus and rear focus at a high zoom ratio and increase the close-up shooting magnification.

[0013]

0.8 <(| β2 | / | β3 |) <1.2 (1) | β2 | <| β4 | (2) | β3 | <| β4 | (3)

If the lower limit of conditional expression (1) is not reached, the range over which the second lens group moves for zooming is widened, and if the zooming range is to be widened to a wider angle side, the first lens group and the second lens group are moved. There is a problem that the distance from the lens group becomes too small (the two interfere with each other), and the zooming range cannot be widened to the wide-angle side. Also, the front focus at the wide-angle end due to zooming is such that the first lens group moves to the image plane side on the optical axis when the imaging magnification decreases, that is, when focusing is performed in the infinity direction. If the distance between the two lens groups is small, the focus range of the first lens group is limited, which is not preferable. Further, if an attempt is made to obtain the same zoom ratio as a lens within the range of the conditional expression (1), there is a problem that the overall length becomes longer than this.

When the value exceeds the upper limit of the conditional expression (1), the range in which the second lens unit moves for zooming may be narrow. Easy. However, if the magnification of the second lens group is large, the height of the incident principal ray of the first lens group is far away from the optical axis.
It is necessary to increase the effective lens diameter of the first lens group in order to secure the light amount, which is not preferable. In addition, since the difference in magnification between the first lens group and the second lens group becomes large, there is a problem that fluctuation in aberration during front focus becomes large.

If conditional expressions (2) and (3) are not satisfied, the height of the off-axis emitted light beam is greatly deviated from the optical axis. It is necessary to increase the diameter, and there is a problem that the lenses subsequent to the third lens group are increased in diameter and size. In addition, the amount of movement of the third and subsequent lens units for focus adjustment increases, and it becomes difficult to perform efficient rear focus adjustment.

In the zoom lens according to the present invention, the combined focal length f1 of the first lens unit and the combined focal length f2 of the second lens unit are set to satisfy the following conditions regardless of the zoom state within the entire zoom range. It is desirable to set the lens parameters so as to satisfy the conditional expression (4). This conditional expression indicates a condition for performing focus adjustment, that is, front focus by the first lens group.

[0018]

## EQU2 ## 3.0 <(f1 / | f2 |) <4.0 (4)

If the lower limit of this conditional expression is exceeded, the amount of movement of the second lens unit for zooming increases, so that the second lens unit comes closer to the first lens unit when zooming to the wide-angle end. Therefore, at the time of zooming toward the wide-angle end, the distance between the first lens unit and the second lens unit becomes too narrow, and it becomes difficult to achieve high zooming over a wide-angle range, such as a problem of interference between the two. When the value exceeds the upper limit of this conditional expression, it is advantageous for a high zoom ratio. However, since the height of off-axis incident light rays is largely separated from the optical axis, the effective lens diameter of the first lens unit becomes large. There is a problem. In order to perform front focus in this state, it is necessary to further increase the lens effective diameter, and there is a problem that the first lens effective diameter becomes too large.

In order to enable front focus adjustment by the first lens group while maintaining a high zoom ratio, it is preferable to set lens parameters so as to satisfy the following conditional expression (5). This conditional expression (5) is a conditional expression that further limits the lower limit of conditional expression (4).

[0021]

3.5 <(f1 / | f2 |) <4.0 (5)

For the same reason as described above, when the value goes below the lower limit of conditional expression (5), it tends to be difficult to physically widen the wide-angle end toward the wide-angle range, but the full angle of view becomes large. 4
In order to provide a wide-angle range exceeding 5 degrees at the wide-angle end of the zoom lens, it is necessary to set a value that does not fall below a lower limit value of conditional expression (5).

It is more preferable that the zoom lens according to the present invention further satisfies the following conditional expression (6).

[0024]

1.0 <(| f2 | / | f4 |) <1.2 (6)

If the lower limit of conditional expression (6) is not reached, it is advantageous for a high zoom ratio, but the amount of movement of the lens unit for rear focusing increases, so that spherical aberration is positive on the telephoto side. And it becomes difficult to widen the variable power range to the telephoto side in view of aberration correction. Conversely, if the variable power range is widened to the wide angle side, there is a problem that it is necessary to increase the effective diameter of the first lens group in order to secure the amount of incident light.
On the other hand, when the value exceeds the upper limit of conditional expression (6), the distance between the first lens unit and the second lens unit on the wide-angle side becomes narrow, and it becomes difficult to widen the zoom range on the wide-angle side. In this case, the movement amount of the lens group for rear focus is small, but in order to enable close-up photographing by front focus, it is necessary to increase the lens effective diameter to secure the light amount, which is not preferable. .

In the zoom lens according to the present invention, automatic focus adjustment from the wide-angle end to the telephoto end is possible with at least one lens group after the third lens group, but at least one lens after the third lens group at the telephoto end. When both the automatic focus adjustment by one lens group and the manual focus adjustment by the first lens group are used, the close-up shooting magnification can be further increased. Of course, it is also possible to perform manual focus adjustment only by moving the first lens group in the entire zoom range. That is, by moving the two focus adjustment lens groups in the optical axis direction in an arbitrary combination, different conjugate lengths are obtained even at the same photographing magnification. As can be seen from the above, various focus adjustments can be made in accordance with the purpose of photographing, and photographing in a photographing area, which was normally difficult, can be easily performed.

In the zoom lens according to the present invention, the focus can be adjusted at infinity by moving the wide-angle end toward the long focal length during zooming, and the zoom lens can be used as a general photographing lens.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a zoom lens according to the present invention comprises five lens groups G1 to G5 arranged in order from an object. Are positive, negative, positive, negative, and positive as shown in the figure. First
The lens group includes a negative meniscus lens having a convex surface facing the object side and a cemented lens of a biconvex lens, and a positive meniscus lens having a convex surface facing the object side. Second
The lens group includes at least one negative lens, a cemented lens of a positive meniscus lens having a concave surface facing the object side, and a biconcave lens. The third lens group includes at least one positive lens, the fourth lens group includes at least one negative lens, and the fifth lens group includes at least one positive lens. It has a convex lens and a cemented lens of a negative meniscus lens having a concave surface facing the object side.

In this zoom lens, as the magnification is changed from the wide-angle end to the telephoto end, the second lens group moves on the optical axis from the object side to the image plane side, and the third lens group moves from the image plane side to the object side. Then, the fifth lens group is moved on the optical axis to correct the image plane position and the automatic focus adjustment is performed, and the first lens group is manually moved on the optical axis to adjust the front-side manual focus. Is performed. Here, since the fifth lens group performs the automatic focus adjustment together with the image plane position correction, the mechanism for movement can be simplified, and the lens group is used for automatic focusing. A large movable range can be secured. If such a large moving range can be secured, it becomes easy to perform focus adjustment during close-up shooting.

[0030]

[Embodiment 1] FIG. 2 shows the configuration of a zoom lens according to a first embodiment of the present invention. This zoom lens includes first to fifth lens groups G1 to G5 as shown. The first lens group G1 includes a cemented lens 11 having a negative meniscus lens 11a and a biconvex lens 11b with a convex surface facing the object side, and a positive meniscus lens with a convex surface facing the object side. The second lens group G2 includes a biconcave lens 21.
And a cemented lens 22 comprising a positive meniscus lens 22a having a concave surface facing the object side and a biconcave lens 22b. The third lens group G3 includes a cemented lens 31 having a biconvex lens 31a and a negative meniscus lens 31b having a concave surface facing the object side, and a biconvex lens 32. The fourth lens group G4 includes a cemented lens 41 having a positive meniscus lens 41a and a biconcave lens 41b with the concave surface facing the object side, and a biconcave lens 42. The fifth lens group G5 includes a biconvex lens 51 and a biconvex lens 52.
a and a negative meniscus lens 52 having a concave surface facing the object side
b, and a biconvex lens 53.

Table 1 shows lens data of the zoom lens according to the first embodiment. The zoom magnification of the zoom lens is β = −0.028 to −0.20, the F number is Fno = 2.8 to 4.0, and the angle of view is 2ω = 3.
8.6 ° to 0.9 °.

[0032]

Table 1 Lens surface Curvature radius Surface spacing Abbe number Refractive index (S) (r) (d) (ν) N 1) 88.388 1.2 25.35 1.80518 2) 27.791 5.0 60 .14 1.62041 3) -59.783 0.1 4) 30.396 3.0 60.14 1.62041 5) 360.668 (variable) 6) -54.002 1.0 57.53 1. 67025 7) 15.224 1.7 8) -32.820 1.8 25.35 1.80518 9) -8.685 1.0 57.53 1.67025 10) 14.926 (variable) 11) 38 .981 2.0 48.97 1.53172 12) -7.827 1.0 25.35 1.80518 13) -17.820 0.1 14) 13.183 1.5 82.52 1.49782 1 ) -37.249 (variable) 16) -19.600 1.5 27.61 1.755520 17) -5.567 1.0 57.03 1.6262280 18) 60.748 0.8 19) -15 .583 1.0 54.01 1.661720 20) 8.932 (variable) 21) 36.025 2.5 53.75 1.69350 22) -32.621 0.1 23) 18.037 4.5 82.52 1.49782 24) -11.551 1.0 25.35 1.80518 25) -44.948 0.1 26) 18.900 2.5 64.10 1.51680 27) -42.501 13.1

When performing zooming with this zoom lens, the wide-angle end position (POS.1) and the intermediate position (POS.1) are used.
2) and at the telephoto end position (POS.3), the relationship between the distance (d0) from the first lens surface to the object and the value of the variable surface spacing (d5, d10, d15, d20) is shown. It is shown in Table 2. This table also shows the magnification β at each position.

[0034]

[Table 2] POS. 1 POS. 2 POS. 3 (Wide-angle end) (Middle) (Telephoto end) Magnification β -0.028 -0.130 -0.200 d0 274.70 274.70 274.70 d5 3.30 15.06 16.50 d10 25.77 7.55 2.73 d15 6.62 13.08 16.46 d20 7.92 8.32 7.79

Table 3 shows an example of the value of the variable surface interval after the focus adjustment when the zooming operation is performed as described above.
In Table 3, POS. 4 is the wide-angle end (PO
S. 1) shows a case where double focus adjustment is performed by the first lens group and the fifth lens group in POS. 5 shows a case where manual focus adjustment is performed only by the first lens group at the wide-angle end (POS. 1). 6 shows a case in which automatic focus adjustment is performed by the fifth lens group at the telephoto end (POS. 3). 7 is at the telephoto end (PO
S. 3) shows a case where double focus adjustment is performed by the first lens group and the fifth lens group in 3).

[0036]

[Table 3] POS. 4 POS. 5 POS. 6 POS. 7 (Wide-angle end) (Wide-angle end) (Telephoto end) (Telephoto end) Magnification β -0.010 -0.016 -0.270 -0.500 d0 748.93 454.16 236.77 140.98 d51 .55 1.55 16.50 20.69 d10 25.77 25.77 2.73 2.73 d15 6.62 6.62 16.46 16.46 d20 7.98 7.92 3.70 3.70

Values corresponding to the above-mentioned conditional expressions (1) to (4) in the case of the zoom lens of the first embodiment, that is,
Table 4 shows the condition corresponding values.

[0038]

Table 4 β -0.028 -0.130 -0.200 | β2 | 0.41 0.96 1.16 | β3 | 0.48 0.94 1.22 | β4 | 2.02 2.18 1.98 f1 = 32.0 f2 = −8.3 | β2 | / | β3 | = 0.84 to 1.02 f1 / | f2 | = 3.86

In the zoom lens according to the first embodiment, the POS. 1, POS. 3, POS. 4, POS. FIGS. 3 to 6 show various aberrations respectively corresponding to FIG. In these aberration diagrams, d represents the d-line aberration, and g represents the g-line aberration. In the astigmatism, the solid line represents the sagittal image plane, and the broken line represents the meridional image plane.

[0040]

[Embodiment 2] FIG. 7 shows the configuration of a zoom lens according to a second embodiment of the present invention. This zoom lens is also constituted by first to fifth lens groups G1 to G5 as shown. The first lens group G1 includes a cemented lens of a negative meniscus lens having a convex surface facing the object side and a biconvex lens,
And a positive meniscus lens having a convex surface facing the object side.
The second lens group G2 includes a biconcave lens, and a cemented lens of a positive meniscus lens having a concave surface facing the object side and a biconcave lens. The third lens group G3 includes a cemented lens of a biconvex lens, a negative meniscus lens having a concave surface facing the object side, and a biconvex lens. The fourth lens group G4 includes two biconcave lenses.
The fifth lens group G5 includes a biconvex lens, a cemented lens of a biconvex lens, a negative meniscus lens having a concave surface facing the object side, and a biconvex lens.

Table 5 shows lens data of the zoom lens according to the second embodiment. The zoom magnification of the zoom lens is β = −0.028 to −0.20, the F number is Fno = 2.8, and the angle of view is 2ω = 38.6 ° to
1.0 °.

[0042]

Table 5 Lens surface Curvature radius Surface distance Abbe number Refractive index (S) (r) (d) (ν) N 1) 93.014 1.2 25.35 1.80518 2) 28.003 6.0 60 .64 1.60311 3) -62.805 0.1 4) 28.016 4.0 60.14 1.62041 5) 352.202 (variable) 6) -71.668 1.0 57.53 1. 67025 7) 16.952 2.0 8) -17.471 2.2 25.35 1.80518 9) -8.182 1.0 58.50 1.65160 10) 19.056 (variable) 11) 23 .896 3.6 48.97 1.53172 12) -9.079 1.2 25.35 1.80518 13) -17.328 0.1 14) 14.710 2.5 82.52 1.49782 1 ) -102.121 (variable) 16) -29.107 1.0 57.03 1.626280 17) 12.730 0.8 18) -21.783 1.0 54.01 1.661720 19) 16. 814 (variable) 20) 50.588 2.0 55.60 1.69680 21) -28.001 0.1 22) 27.289 4.0 82.52 1.49782 23) -9.618 1.0 25.35 1.80518 24) -26.971 0.1 25) 19.550 3.0 64.10 1.51680 26) -29.402 13.7

When performing zooming with this zoom lens, the wide-angle end position (POS.1) and the intermediate position (POS.1) are used.
2) and at the telephoto end position (POS. 3), the relationship between the distance (d0) from the lens first surface to the object and the value of the variable surface spacing (d5, d10, d15, d19) Are shown in Table 6. This table also shows the magnification β at each position.

[0044]

[Table 6] POS. 1 POS. 2 POS. 3 (Wide-angle end) (Middle) (Telephoto end) Magnification β -0.028 -0.130 -0.200 d0 273.14 273.14 273.14 d5 2.59 14.35 15.79 d10 24.75 6.53 1.17 d15 6.26 12.72 16.10 d19 7.40 7.73 7.22

Table 7 shows an example of the value of the variable surface interval after the focus adjustment when the zooming operation is performed as described above.
In Table 7, POS. 4 is the wide-angle end (PO
S. 1) shows a case where double focus adjustment is performed by the first lens group and the fifth lens group in POS. 5 shows a case where automatic focus adjustment is performed only by the fifth lens group at the wide-angle end (POS. 1). 6 shows a case in which automatic focus adjustment is performed by the fifth lens group at the telephoto end (POS. 3). 7 is at the telephoto end (PO
S. 3) shows a case where double focus adjustment is performed by the first lens group and the fifth lens group in 3).

[0046]

[Table 7] POS. 4 POS. 5 POS. 6 POS. 7 (Wide-angle end) (Wide-angle end) (Telephoto end) (Telephoto end) Magnification β -0.010 -0.015 -0.280 -0.500 d0 782.18 535.29 236.77 144.43 d5 1 .74 2.59 15.79 19.62 d10 24.75 24.75 1.71 1.71 d15 6.26 6.26 16.10 16.10 d19 7.54 7.55 2.68 2.68

Values corresponding to the above-mentioned conditional expressions (1) to (4) in the case of the zoom lens of the second embodiment, that is,
Table 8 shows the condition corresponding values.

[0048]

Table 8 β -0.028 -0.130 -0.200 | β2 | 0.41 0.96 1.15 | β3 | 0.48 0.95 1.22 | β4 | 2.02 2.18 1.98 f1 = 32.0 f2 = −8.3 | β2 | / | β3 | = 0.84 to 1.02 f1 / | f2 | = 3.86

In the zoom lens of the second embodiment, the POS. 1, POS. 3, POS. 4, POS. 8 to 11 show various aberrations respectively corresponding to FIG. In these aberration diagrams, d represents the d-line aberration, and g represents the g-line aberration. In the astigmatism, the solid line represents the sagittal image plane, and the broken line represents the meridional image plane.

[0050]

Embodiment 3 FIG. 12 shows the configuration of a zoom lens according to a third embodiment of the present invention. This zoom lens also includes first to fifth lens groups G1 to G5 as shown. The first lens group G1 includes a cemented lens of a negative meniscus lens having a convex surface facing the object side and a biconvex lens, and a positive meniscus lens having a convex surface facing the object side. The second lens group G2 includes a negative meniscus lens having a concave surface facing the object side, and a cemented lens of a positive meniscus lens having a concave surface facing the object side and a biconcave lens. The third lens group G3 includes a cemented lens of a biconvex lens, a negative meniscus lens having a concave surface facing the object side, and a biconvex lens. Fourth lens group G4
Is composed of a cemented lens of a positive meniscus lens and a biconcave lens with the concave surface facing the object side, and a biconcave lens. The fifth lens group G5 includes a biconvex lens, a cemented lens of a biconvex lens, a negative meniscus lens having a concave surface facing the object side, and a biconvex lens.

Table 9 shows lens data of the zoom lens according to the third example. The zoom magnification of this zoom lens is β = −0.028 to −0.17, the F number is Fno = 2.5 to 3.3, and the angle of view is 2ω = 4.
It is 7.4 ° to 5.5 °.

[0052]

[Table 9] Lens surface Curvature radius Surface distance Abbe number Refractive index (S) (r) (d) (ν) N 1) 57.597 1.2 25.35 1.80518 2) 23.164 6.5 60 .14 1.62041 3) -100.907 0.1 4) 25.708 3.8 60.14 1.62041 5) 134.852 (variable) 6) 300.000 1.0 57.53 1.67025 7) 9.186 3.0 8) -35.946 2.2 25.35 1.80518 9) -14.807 1.0 57.53 1.67025 10) 33.055 (variable) 11) 16. 719 2.2 48.97 1.53172 12) -19.826 1.0 25.35 1.80518 13) -35.747 0.1 14) 15.332 1.6 82.52 1.4978 15) -167.6696 (variable) 16) -13.006 1.8 27.61 1.755520 17) -7.843 1.0 57.03 1.626280 18) 23.841 0.819)- 18.514 1.0 54.01 1.661720 20) 22.948 (variable) 21) 80.948 3.0 53.75 1.69350 22) -18.463 0.1 23) 27.743 6. 0 82.52 1.49782 24) -9.854 1.0 25.35 1.80518 25) -31.419 0.1 26) 21.612 4.5 64.10 1.51680 27) -25. 879

When zooming is performed by the zoom lens, the wide-angle end position (POS.1) and the intermediate position (POS.1) are used.
2) and at the telephoto end position (POS. 3), the relationship between the distance (d0) from the lens first surface to the object and the value of each of the variable surface intervals (d5, d10, d15, d20). Are shown in Table 10. This table also shows the magnification β at each position.

[0054]

[Table 10] POS. 1 POS. 2 POS. 3 (Wide-angle end) (Middle) (Telephoto end) Magnification β -0.028 -0.120 -0.170 d0 213.38 213.38 213.38 d5 0.75 13.18 14.79 d10 25.42 7.82 3.68 d15 3.75 8.92 11.45 d20 5.81 4.93 4.93

Table 11 shows examples of values of the variable surface interval after the focus adjustment when the zooming operation is performed as described above. In Table 11, POS. 4 shows a case where double focus adjustment is performed by the first lens group and the fifth lens group at the wide angle end (POS. 1).
5 shows a case where manual focus adjustment is performed only by the first lens group at the wide-angle end (POS. 1). 6 shows a case in which automatic focus adjustment is performed by the fifth lens group at the telephoto end (POS. 3). Reference numeral 7 denotes a case where double focus adjustment is performed by the first lens unit and the fifth lens unit at the telephoto end (POS. 3).

[0056]

[Table 11] POS. 4 POS. 5 POS. 6 POS. 7 (Wide-angle end) (Wide-angle end) (Telephoto end) (Telephoto end) Magnification β -0.010 -0.026 -0.200 -0.320 d0 613.30 230.41 203.47 137.87 d50 .29 0.29 14.79 18.30 d10 25.42 25.42 3.68 3.68 d15 3.75 3.75 11.45 11.45 d19 6.03 5.81 3.34 3.34 3.34

The values corresponding to the above-mentioned conditional expressions (1) to (4) in the case of the zoom lens of the third embodiment, that is,
Table 12 shows the condition corresponding values.

[0058]

Table 12 β -0.028 -0.120 -0.170 | β2 | 0.39 0.87 1.04 | β3 | 0.48 0.89 1.08 | β4 | 1.19 1.10 1.09 f1 = 32.0 f2 = −8.8 | β2 | / | β3 | = 0.81 to 0.98 f1 / | f2 | = 3.64

In the zoom lens according to the third embodiment, the POS. 1, POS. 3, POS. 4, POS. FIGS. 13 to 16 show various aberrations respectively corresponding to FIG. In these aberration diagrams, d represents the d-line aberration, and g represents the g-line aberration. In the astigmatism, the solid line represents the sagittal image plane, and the broken line represents the meridional image plane.

[0060]

As described above, the zoom lens according to the present invention corrects the image point position by moving at least one of the third to fifth lens units on the optical axis.
Manual focus adjustment is performed by manually moving the first lens group on the optical axis, and automatic focus adjustment is performed by automatically moving at least one of the third to fifth lens groups on the optical axis. That is, since the combination of the manual front focus and the automatic rear focus is combined, the disadvantages of both types can be compensated for, the advantages can be utilized, and the effective diameter of the first lens group can be reduced,
In addition, a zoom lens having a high zoom ratio and a high close-up shooting magnification can be obtained.

In the zoom lens according to the present invention, the magnification β2 carried by the second lens group in the entire zooming range, the magnification β3 carried by the third lens group in the entire zooming range, and the fourth lens group in the full zooming range. Is satisfied by any of the above-mentioned conditional expressions (1) to
It is preferable to set the lens specifications so as to satisfy the condition (3), thereby enabling both front focus and rear focus at a high zoom ratio and increasing the close-up shooting magnification.

In the zoom lens system according to the present invention, the combined focal length f1 of the first lens unit and the combined focal length f2 of the second lens unit are set in the same manner as described above regardless of the zoom state within the entire zoom range. It is desirable to set the lens parameters so as to satisfy the conditional expression (4).
Focus adjustment can be performed by the first lens group in a high zooming state on the wide-angle range while the effective diameter of the lens group is suppressed.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a refractive power arrangement of each lens group of a zoom lens according to the present invention.

FIG. 2 is a cross-sectional view illustrating a lens configuration of a zoom lens according to a first example.

FIG. 3 illustrates a POS. 1
FIG. 9 is an aberration diagram showing various aberrations corresponding to.

FIG. 4 illustrates a POS. 3
FIG. 9 is an aberration diagram showing various aberrations corresponding to.

FIG. 5 illustrates a POS. 4
FIG. 9 is an aberration diagram showing various aberrations corresponding to.

FIG. 6 illustrates a POS. 7
FIG. 9 is an aberration diagram showing various aberrations corresponding to.

FIG. 7 is a sectional view illustrating a lens configuration of a zoom lens according to a second example.

FIG. 8 illustrates a POS. 1
FIG. 9 is an aberration diagram showing various aberrations corresponding to.

FIG. 9 illustrates a POS. 3
FIG. 9 is an aberration diagram showing various aberrations corresponding to.

FIG. 10 illustrates a POS.
4 is an aberration diagram illustrating various aberrations corresponding to FIG.

FIG. 11 illustrates a POS.
7 is an aberration diagram showing various aberrations corresponding to FIG.

FIG. 12 is a sectional view showing a lens configuration of a zoom lens according to Example 3.

FIG. 13 illustrates a POS.
FIG. 3 is an aberration diagram showing various aberrations corresponding to 1. FIG.

FIG. 14 illustrates a POS.
FIG. 7 is an aberration diagram showing various aberrations corresponding to No. 3;

FIG. 15 illustrates a POS.
4 is an aberration diagram illustrating various aberrations corresponding to FIG.

FIG. 16 illustrates a POS.
7 is an aberration diagram showing various aberrations corresponding to FIG.

[Explanation of symbols]

 G1 to G5 First to fifth lens groups

Claims (4)

[Claims] 1. A first lens group having a positive refractive power, a second lens group movable for zooming and having a negative refractive power, arranged in order from the object side on the optical axis, Third movable with positive refractive power
A lens group, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power, wherein at least one of the third to fifth lens groups is moved on the optical axis. The first lens group is manually moved on the optical axis to perform manual focus adjustment, and at least one of the third to fifth lens groups is automatically moved to the optical axis. A zoom lens that is moved upward to perform automatic focus adjustment. 2. A magnification β2 carried by the second lens group within the entire zoom range, a magnification β3 carried by the third lens group within the entire zoom range, and a magnification carried by the fourth lens group within the entire zoom range. β4 is the conditional expression: 0.8 <(| β2 | / | β3 |) <1.2 | β2 | <| β4 || β3 | <| β4 The zoom lens according to claim 1, wherein | 3. The combined focal length f1 of the first lens group.
And the combined focal length f2 of the second lens group satisfies the following conditional expression: 3.0 <(f1 / | f2 |) <4.0 for any zoom state within the entire zoom range. The zoom lens according to claim 1, wherein: 4. A lens group for correcting the image point position;
The zoom lens according to claim 1, wherein the lens groups that perform the automatic focus adjustment are the same lens group.