JPH03293309A - Variable power lens - Google Patents

Abstract

PURPOSE:To obtain the variable power lens having a high variable power ratio and being compact by allowing a lens group of three groups having positive, negative and positive refracting power from an object side to have a prescribed characteristic. CONSTITUTION:The variable power lens is constituted of a first group I having positive refracting power, a second group II of negative refracting power, and a third group of positive refracting power in order from an object side. This first group I contains one piece of high dispersion negative lens d1 and at least one piece of positive lens d3, and second group II contains one piece of high dispersion positive lens d7 and at least one piece of negative lens d5, and also, they are constituted of lenses of three pieces or less in all. A third lens III has at least one piece of high dispersion negative lens d12 and one piece or two pieces of positive lens components d10 on the object side of this lens d12. A second group II and a third group III have as aspherical face, and move on an optical axis at the time of variable power. In such a way, the variable power lens which has a high variable power ratio and a large aperture ratio, and also, whose compaction, low cost and high performance of an aberration are attained can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable power lens, and particularly to a variable power lens with a large variable power ratio that can be applied to small cameras such as video cameras and electronic still cameras. In recent years, with the packaging of electronic components and improvements in the integration rate,
Camera bodies such as video cameras are becoming much more compact in terms of weight and volume. On the other hand, it is also remarkably low in price and cost. However, although the absolute values of the weight, volume, and cost of lenses relative to the entire camera are improving little by little, the relative values relative to the entire camera are increasing year by year. Under these circumstances, demands for downsizing and cost reduction are becoming stronger. On the other hand, lenses are equipped with higher functionality, such as a larger aperture ratio to compensate for the lack of illuminance caused by the miniaturization of image sensors, and higher aberration performance to accommodate higher pixel and resolution requirements. There is also the aspect that it is being sought after. Currently, especially in the field of video cameras, variable magnification lenses with a variable magnification ratio of about 6x are mainstream. Many zoom lenses having such a high zoom ratio and a large aperture ratio with an F number of approximately Fl and 6 have been proposed in the past, each consisting of four or five groups. However, most of them consist of about 13 to 15 pieces, so they can be made compact and
It can no longer be said that it can satisfy current demands such as cost reduction. In recent years, there has been a trend to reduce the number of lens components by using aspheric surfaces in order to satisfy such demands. For example, the zoom lens disclosed in Japanese Patent Application Laid-Open No. 57-27219 is not a 6x zoom lens, but it is a system consisting of three groups (positive, negative, positive), and the first group is an image point position correction group (compensator), and the second By moving the group on the optical axis as a variable magnification group (variator) and using one aspherical surface in each group, the F
It consists of 12 lenses that provide a 3x zoom lens. However, with this zoom lens, its zoom configuration, lens shape, arrangement, etc. cannot be said to be effective, and considering its specifications, it cannot be said that the number of lenses in the lens is small. Furthermore, it is impossible to extend this zoom lens to a high variable power of about 6x. The reason for this is that in addition to the above-mentioned inappropriate lens shape and arrangement, the lens also has the following drawbacks. In other words, since the third lens group is not moved during zooming, the first lens group necessarily needs to move as a compensator lens group. At that time, if you try to achieve a high zoom ratio of about 6x, you will end up with a zoom solution in which the first group moves considerably toward the object side at the wide end or middle range (intermediate focal length). Therefore, the diameter of the first group (front lens) is considerably larger than that of a zoom lens consisting of the fourth and fifth groups, and the zoom lens has the disadvantage that it is considerably heavier. On the other hand, Japanese Patent Laid-Open Nos. 61-110112 and 1987-107013 disclose four-group zoom lenses that have a considerably effective lens shape, arrangement, and arrangement of aspherical surfaces, and have significantly reduced the number of lenses. There are some that have been disclosed. In JP-A-61-110112, each group is simply constructed with a four-group system of positive, negative, negative, and positive, and by effectively using four aspherical surfaces, a 6x zoom is achieved with only eight elements in the entire system. are doing. However, although this zoom lens has an excellent structure, its aberration performance is quite poor, and it is considered difficult to satisfy current performance requirements. In addition, in Japanese Patent Application Laid-open No. 60-107013, there are four
A schematic diagram of a group consisting of eight sheets is shown. Since numerical data has not been disclosed, its performance and size cannot be determined, but the specs are F2.0 4x zoom, so it cannot meet the current demands for a high zoom ratio and large aperture ratio. Others: JP-A-63-304218, JP-A-64-4
No. 4907. In Japanese Patent Application Laid-Open No. 1-223408, etc., the second group is one sheet,
A zoom lens has been proposed that consists of a positive, negative, and positive three-group system with one or two lenses in the first group, and uses an aspherical surface to reduce the number of lenses. In these lens types, the second group, which plays the main role in variable power and moves largely on the optical axis during variable power, is composed of a single negative lens. Therefore, since chromatic aberration is not corrected within the second group, the chromatic aberration fluctuates greatly due to zooming, and performance cannot be guaranteed when applied to high zooming. In fact, these zoom lenses have a low variable power ratio of 2 to 3 times and a dark F number of around 2 to 4.This variation in chromatic aberration cannot be improved even by making extensive use of aspherical surfaces. Furthermore, given the current performance requirements (including chromatic aberration) with this type of lens, there is no hope of achieving a zoom ratio of at most 3x, and it is difficult to achieve a zoom ratio as high as 6x. is difficult. Furthermore, JP-A-64-91110 and JP-A-1-1856
No. 08 also proposes an innovative zoom lens. Japanese Patent Laid-Open No. 64-91110 proposes a zoom lens having substantially the same lens shape and configuration as the three-group zoom lens proposed by the applicant in Japanese Patent Laid-Open No. 64-88511. However, the part corresponding to the second group is separated into a negative group consisting of two negative lenses and a positive group consisting of one positive lens, and although the lens shape appears to be a three-group system, the actual configuration is There are four groups. And the number of constituent sheets is 8 to 1, which is the same as the 3rd group system.
It achieves 3x zoom while keeping it to a single image. Its magnification is the negative group (actually the second group) and the positive group (actually the third group) mentioned above.
This is done by moving each independently. However, the essential problem with this four-group zoom lens is that the chromatic aberration correction within each group is not completed in the independently moving second and third groups. This means that variations in chromatic aberration cannot be sufficiently suppressed due to variations in the relative positions of both groups due to magnification. This zoom lens suppresses fluctuations in chromatic aberration by devising a zoom solution while keeping the zoom ratio at 3x.
It is quite difficult to achieve double zoom. It can be said that JP-A No. 1-185608 reduces the number of lenses in the zoom lens proposed in JP-A-64-91110 by making extensive use of aspherical surfaces, while increasing the zoom lens to 6x zoom. In other words, JP-A-64-91110
In this issue, the second group is made up of one negative single lens, the third group is made up of one positive single lens, and the fourth group is also simplified. but,
Even in this case, the above-mentioned chromatic aberration fluctuation is large, so although considerable improvements have been made to the zoom solution, the residual chromatic aberration is still large and it is difficult to meet the current performance requirements. Furthermore, since the zoom solution places considerable emphasis on chromatic aberration correction, the amount of movement of the second and third groups, which are movable groups, has increased considerably, resulting in a longer overall length. In particular, the outer diameter of the front element, which has a large impact on weight, is considerably larger than that of conventional lenses with the same specs, so from the standpoint of compactness, I have to say that it has gotten worse. do not have. As described above, although the zoom lens proposed in Japanese Patent Application Laid-open No. 1-185608 has achieved the objective of reducing the number of lenses, it does not satisfy the current needs in terms of compactness and monochromatic aberration performance. Furthermore, like JP-A No. 1-185608, 4 of positive, negative, positive,
A zoom lens that can also suppress variations in chromatic aberration due to its group configuration is disclosed in Japanese Patent Laid-Open No. 2-39011. Three aspherical surfaces are used for this.
The double zoom consists of 8 images. cost, performance,
Although it is possible from a size perspective, the diameter of the front element cannot be said to be small, and there is no significant advantage over existing ones in terms of weight. In addition, there is a problem in that comatic aberration (Linnenfeller) in the sagittal direction, which is difficult to show in an aberration diagram, is very large, and performance deterioration in off-axis directions is large. On the other hand, in order to respond to compactness and reduction in the number of lenses, the applicant has
No. 520, etc., only 8 without using an aspheric surface.
We proposed a zoom lens with three positive and negative groups consisting of two lenses. Although these zoom lenses are very compact and have good performance, their magnification ratio is only about 2 to 3 times.
The required high zoom ratio has not been achieved. In addition, by moving each group in a positive, negative, and positive three-group system similar to these, zoom lenses were proposed for use in reflex cameras and compact cameras, with the aim of reducing the number of lenses and increasing zoom ratio. JP-A-54-30855, JP-A No. 54-8
No. 0143, Japanese Patent Application Laid-Open No. 2-39116, etc. The variable magnification ratio and the number of constituent sheets are, in order, 2.4 times/10 sheets, 3 times/11 sheets, and 3 times 712 sheets. As described above, the variable power ratio is insufficient, the third group and the second group in particular have not been sufficiently simplified, and cost reduction has not been achieved. As can be seen from the above conventional example, a zoom lens with a three-group system and a variable power ratio of 6x has not been realized. As a result, the magnification ratio is 6
In order to achieve doubling, it is considered a necessary condition to be composed of four or more groups. In other words, in a configuration with three or fewer groups, the maximum variable power ratio is considered to be around 3x. From the viewpoint of the number and size of components, it is clear that the 3-group system is more advantageous than the 4-group system. However, in order to correct aberrations, in a lens system composed of a spherical system,
If we consider aspherical surfaces as a slight improvement on spherical systems, we can indirectly prove through considerable trial and error that even in lens systems using aspherical surfaces, it is not possible to obtain an appropriate zoom solution and each lens configuration with a 3-group system. This has been proven and is semi-common sense. Even today, 3
This may be the reason why there is no 6x zoom lens in the group (Japanese Unexamined Patent Publication No. 57-27219).
issue. 63-304218, 84-44907, and JP-A-1-223408, etc.). However, it is clear from aberration theory that aspheric surfaces are not simply extensions of spherical systems, but that there are also lens systems that can be realized only by using aspheric surfaces. ing. Therefore, in view of this situation, the present invention provides a variable power lens that has a high zoom ratio and a large aperture ratio, and is compact, low cost, and has high aberration performance. By effectively using an aspheric surface in the three-group system, which is more advantageous for downsizing and reducing the number of lens elements, a bright variable magnification lens with a variable power ratio of about 6x and an FNO of about 1.6 can be created with a high The aim is to achieve this while maintaining performance. In order to achieve the above object, the variable magnification lens of the present invention includes a first group having positive refractive power in order from the object side. The second group has negative refractive power and the third group has positive refractive power.
The first group is configured to include one high dispersion negative lens and at least one positive lens;
The second group includes one high-dispersion positive lens and at least one negative lens, and is composed of three or less lenses in total, and the third group includes at least one high-dispersion negative lens and the high-dispersion negative lens. The dispersion negative lens is configured to include one or two positive lens components on the object side, and the second group and the third group have aspherical surfaces and move on the optical axis when changing magnification. There is. Generally, in order to make a zoom lens more compact, it is necessary to shorten the overall length and further reduce the amount of movement. In the present invention, in order to ensure compactness including the lens barrel configuration and sufficient back focus, a three-group system of positive and negative groups is used. Of the three groups mentioned above, magnification change is mainly achieved by increasing the refractive power of the central negative second group and moving it along the optical axis. Correspondingly, at least the positive third group is configured to be moved in order to suppress fluctuations in the image point position and further to achieve compactness. The reason for this is that the third group generally has a stronger refractive power than the first group, and therefore has the advantage of being able to correct fluctuations in the image point position with a small amount of movement. Therefore, it is a necessary condition for achieving a zoom ratio of approximately 6x in a three-group system that at least the third group moves along the optical axis together with the second group during zooming. Having a large number of movable lens groups is advantageous in terms of compactness and aberration correction, but it cannot be overlooked that it also increases costs due to the lens barrel configuration. If this cost difference is quite large and there is a restriction that you want to use two moving lens groups when changing magnification, then the first lens group can be fixed and the moving groups when changing magnification can be moved to the second and third groups. When changing the magnification from the telephoto end to the wide end, configuring the third group to draw a trajectory that moves toward the -object side and makes a U-turn on the way is the best way to make it more compact and correct aberrations. Highly desirable. In addition, especially when the first group is fixed, the third group can also be operated as a focusing lens in combination with TTL autofocus to define the relationship with the movement of the second group. Another advantage is that it eliminates the need for a cam ring. Conversely, if the third lens group is fixed during zooming, the first lens group will inevitably
The group will have a compensator-like role, but the zoom solution will be such that its movement is convex toward the object side or moves considerably toward the object side from the wide end to the middle range, and the surroundings at the middle range and wide end end up being distorted. The vignetting caused by the first group of light becomes large, and it becomes necessary to considerably increase the diameter of the first group (front lens) to ensure illuminance, resulting in a significant increase in weight, making it impossible to achieve compactness. Another advantage of having the third group as a movable group is that, assuming the above-mentioned TTL autofocus, the movement of the third group makes it possible to take extremely close-up shots. It will be done. Next, specific thickening will be explained. In order to have the main variable magnification function in the second group, the first and second groups
The diameter and angle of the light beam passing through the lens group vary greatly depending on the magnification. Therefore, variations in aberrations caused by zooming vary considerably depending on the suitability of the configurations of the first and second groups. Traditionally, the majority of lenses were constructed with three lenses each in the first and second groups, but in recent years, monochromatic aberrations can be corrected even with a simpler configuration by making extensive use of aspherical surfaces. It has become to. The above-mentioned Japanese Patent Application Publication No. 1-185608 falls under this category. However, as mentioned above, if the second group (or first group) is composed of a single element, chromatic aberration fluctuations will increase, and in order to suppress this, the zoom resolution will be limited, and you will have to accept a considerable increase in size. It won't happen. In order not to impair compactness, gJ1 group and
It is necessary to complete chromatic aberration correction for each group. That is, it is necessary to provide one negative high-dispersion lens in the positive first group and one positive high-dispersion lens in the negative second group, and to configure the configuration with three or less lenses in total. Next, the specific configuration of the third group will be described. The third group is the second
It plays the important role of refracting the divergent light beam after the group emission and finally forming an image. Furthermore, it is necessary to completely correct residual aberrations with this group, so lenses with a variable magnification ratio of 6x and an F number of about 1.6 are often constructed with 5 or 6 lenses. By using an aspheric surface, aberrations can be corrected even if this third group is more simply constructed with five or fewer lenses. However, the present invention requires the following configuration. That is, in order to complete the chromatic aberration correction in the third group, it is necessary to use at least one high dispersion negative lens. Since the third group has a strong positive refractive power, the amount of aberration generated is quite large. is preferably composed of a single lens with strong refractive power. This negative lens serves as the main element for correcting monochromatic aberrations such as spherical aberration, coma aberration, curvature of field, and distortion, as well as for correcting chromatic aberrations such as Hosochi chromatic aberration and lateral chromatic aberration. requires caution. Further, the third group needs to be configured to include one or two positive lens components on the object side of the at least one high dispersion negative lens. With this positive object side component, the second
By immediately refracting the diverging light beam after exiting the group, it is possible to suppress the enlargement of the third group and the occurrence of aberrations. However, if this object side component is composed of three or more positive lens components, the following problem will occur. First, the number of constituent sheets increases. Secondly, since the positive refractive power is concentrated on the object side, the light beam is considerably converged after exiting this object side component, making it impossible to obtain a sufficient back focus. Thirdly, in order to correct Hosso chromatic aberration, it becomes necessary to make the refractive power of the negative lens extremely large, resulting in excessive occurrence of higher-order aberrations. Now, in such a thick lens configuration, it is preferable that the following conditional expression (2) be satisfied. 0.20<φI/IφU I<O,sl...
...■Here, φI: composite refractive power of the first group φII: composite refractive power of the second group. The zoom lens proposed in the above-mentioned Japanese Patent Application Laid-Open No. 84-74519 has a similar configuration with a three-group system, but in comparison, in the present invention, the refractive power φI of the first group is weakened, and the refractive power φI of the first group is By making the second group stronger, it is possible to obtain a desired zoom solution in a 6x class variable power system. Conditional expression (2) indicates the balance of refractive power between the first group and the second group. It is necessary to satisfy this condition in order to mainly concentrate the variable magnification function in the second group and to regulate the movement of the other movable groups advantageously in terms of compactness and performance guarantee. When the lower limit of this conditional expression is exceeded, the degree of divergence of the divergent luminous flux after exiting the second group increases, the third group becomes more crowded, and the second and third groups
Since the amount of aberration generated in each group increases dramatically, it becomes difficult to realize each with a simple configuration, and the performance deteriorates significantly. On the other hand, when the upper limit is exceeded, the movement pattern of the third lens group changes, and in high variable power zoom, it begins to move considerably toward the object side at the wide end. As a result, the second
It becomes necessary to provide a considerably large air gap between the group and the group, which also impairs compactness. At the same time, there is also the problem that it is necessary to increase the outer diameter of the front lens. Further, it is preferable that conditional expression (2) be satisfied, that the third group has one high dispersion lens, and that the third group is composed of a total of five or less lenses. A simple lens that satisfies these conditions and is advantageous in terms of compactness and aberration correction is a negative meniscus lens whose first group is convex toward the object side and a positive lens whose strong surface faces the object side. One example is something that is made up of sheets. To put it more simply, it is desirable that the second group consists of two lenses: a negative lens with a strong refractive surface facing the image side, and a positive lens arranged with a (certain amount of) space between them. In this way, by making both groups each preceded by a negative lens, it is possible to quickly loosen the lens passing angle of the off-axis beam (reducing the angle with the optical axis) and suppress the occurrence of off-axis aberrations. At the same time, it is possible to prevent the outer diameter of the front lens from becoming too large. The arrangement shape of the lens up to this point was
This is similar to what was proposed in No. 4-74519. However, in the zoom solution considered here, the relative ratio of the refractive power of the second group to the first group has become stronger, and the variable power ratio has also increased, so the amount of aberration generated, especially in the second group, has increased. The number has increased dramatically and cannot be put to practical use as it is. Therefore, in the present invention, this problem is solved by using an aspherical surface in the second group. It goes without saying that using a plurality of aspherical surfaces in the second group, preferably also using an aspherical surface in the first group, is advantageous in terms of aberration correction, but at least one aspherical surface in the second group. By using a spherical surface, aberration fluctuations due to zooming can be suppressed to approximately the desired amount. Further, it is desirable that the first group is composed of two elements as described above, and that the following conditional expression (2) is satisfied. C2-C1〉22 ・・・・・・■ Here, C1: Atsbe number of the negative lens in the first group relative to the d-line C2: d of the positive second lens in the first group This is the Atsbe number for the line. Furthermore, it is desirable to configure the second group with two elements as described above and to satisfy the following conditional expression (■■). 0, 4<re/r7<1.0 ・・・・・・■shi, -shi4>1G ・・・・・・■where, r6: Image side surface of the negative lens in the second group Paraxial radius of curvature r7: Paraxial radius of curvature of the object side surface of the positive lens in the second group C3: Atsbe number of the negative lens in the second group with respect to the d line C: d of the positive lens in the second group This is the Atsbe number for the line. Conditional expression (■) defines the difference in dispersion between the two lens materials in each of the first group and the second group. The negative lens in the first group and the positive lens in the second group are lenses that use high dispersion materials to correct chromatic aberration in each group, and have refractive powers with opposite signs to the combined refractive power of each group. have However, since only one lens with the same sign as each group is assigned to each group, it is necessary to create a sufficient dispersion difference between both lenses. It becomes necessary to make it considerably stronger. As a result, this causes a large amount of monochromatic aberration, which is difficult to correct even if an aspherical surface is used. Conditional expression (2) indicates the balance between the opposing surfaces of both lenses in the second group, and from another perspective, it defines the shape of the air lens sandwiched between both lenses. This air lens has a particularly large effect on off-axis light on the wide-angle side and on-axis light on the telephoto side. If the value is below this lower limit, distortion and deterioration of image plane properties will become noticeable, especially at the wide end. Conversely, if the upper limit is exceeded, spherical aberration and coma aberration, especially at the telephoto end, deteriorate, making it difficult to obtain the desired performance even if an aspherical surface is used. In addition to satisfying the above conditional expressions (1) and (2), it is preferable to satisfy the following conditional expression (2). fw·φI>0.15...■Here, fw: Synthetic focal length of the entire system at the wide end. Conditional expression (2) defines the lower limit of the refractive power of the first group. In a three-group system (positive, negative, positive), the refractive power of the first group is a major factor in determining the size of the entire lens system. If the lower limit is below, the amount of movement of the second group and the outer diameter of the front lens will increase, so in order to achieve compactness, it is preferable to set the refractive power of the first group so as to satisfy this condition. Among the arrangements of the third group, the one that can achieve the purpose with a smaller number of elements is one that can be configured with, for example, one positive lens, one negative lens, and one or two positive lenses in order from the object side. 3 or 4 lenses in total, 2 positive lenses, 1 negative lens, and 1 positive lens in order from the object side, 2 positive lenses and 1 lens in order from the object side Examples include a total of three negative lenses. The third group having such a configuration has three or four elements, and therefore has a high potential for correcting aberrations and a high ability to secure back focus. The composition of this jIs group, especially in the former two, is similar to that of JP-A-64
This is similar to what was proposed in No.-74519. However, even with such a configuration, it is difficult to guarantee performance under desired lens specifications. In other words, with high specs such as a zoom ratio of 6x and an F number of 1.6, the aberrations remaining in the preceding first and second groups and the aberrations occurring in the third group cannot be corrected as is. . Specifically, spherical aberration, field curvature, etc. are significantly deteriorated. These problems are also exacerbated by the fact that the amount of movement of the third lens group is increased due to the increased variable power ratio compared to JP-A No. 64-74519. In order to effectively solve these problems, the present invention provides a third
By using at least one aspherical surface in the group, the third
The group's ability to correct aberrations, especially spherical aberration, has been greatly improved. This aspheric surface naturally has the ability to correct off-axis aberrations, but by increasing the ability and degree of freedom to control spherical aberrations, other surfaces can concentrate on correcting off-axis aberrations. Therefore, the effect in correcting aberrations is enormous. Note that if particular emphasis is placed on spherical aberration, it is advantageous to arrange the aspherical surface as close to the object side as possible, and to produce an appropriate effect on off-axis aberrations, it is advantageous to arrange the aspherical surface as close to the image side as possible. Since aberrations caused by positive lenses in the third group basically pose a problem, it is preferable to arrange at least one aspherical surface in the positive lens in the third group. Further, it is desirable that the aspheric surface has a shape such that the amount of deviation from the reference plane corresponding to the paraxial radius of curvature increases as the distance from the optical axis increases. However, if a plurality of aspherical surfaces are used in the third group, such a shape may not be achieved. The use of at least one aspherical surface in the third group is a necessary condition for achieving such a configuration of the third group. Next, the arrangement of the aperture will be explained. It is advantageous to arrange the aperture as close to the center of the lens as possible in order to correct aberrations. In the three-group system of the present invention, the space between the second and third groups corresponds to approximately the center of the lens, and it is optimal to arrange them at this position. Further, when changing the magnification, it may remain fixed or may be moved in order to pursue more compactness. Furthermore, in the three-group system of the present invention, the first group may be used for focusing, or the third group may be used for focusing. In extremely close-up photography, it is effective to move the third group or a part of the third group. Furthermore, the third group is also used as a focusing lens, and by dividing it into several small groups and subtly changing the relative positional relationship between them, it has a floating function that suppresses aberration fluctuations during focusing. It is also effective. Similarly, during zooming, it is also effective to slightly change the relative positional relationship of these small groups in order to more highly correct aberration fluctuations caused by zooming. Note that the aspheric surface of the first group is extremely effective when more accurate aberration correction is required, such as correction of spherical aberration at the telephoto end or subtle coma aberration. Further, the variable power lens of the present invention can also be applied to a varifocal lens. Examples of the variable magnification lens according to the present invention will be shown below. However, in each embodiment, r1 to r19 are the radius of curvature of the surface counted from the object side, d1 to d+s are the axial surface spacings counted from the object side, and N, to N0. h, ~v9 indicate the refractive index and Atsube number of each lens with respect to the d-line counted from the object side. Further, f indicates the focal length of the entire system, and FNO indicates the F number. In the examples, a surface with a radius of curvature marked with * indicates that it is an aspherical surface, and is defined by the following equation representing the shape of the aspherical surface. The amount of deviation from the reference plane in the optical axis direction, the paraxial radius of curvature, the height in the direction perpendicular to the optical axis, and the i-th order aspheric coefficient and conic constant. <Example 1> f=52.5-19.0-9.25 F No =
2.32 ~ 1.63 ~ 1.631 ``Ri艷dan-JJJro old'' 4 pieces! L Yuba 1r6 umbrella 8.599 6 3.000 rl+ -98,832 d eye 4.400 r+z 22.588 d+i 1.700 (Ls 5.000~ 8.396~5.582 16 tes, oo. No 1 .51680 64.20 r+7 (1) Performer 1: r6: ε=O,100OOX 10A,=-0
, 21902
17178
1222X 1O-3 As=0.81929X 10-' As=0.98703X 10-"<Example2> f=52.5-19.0-9.25 FNO=2.2
7-1.63-1.633 5.30O 2 1,71300 53,93 -403,794 rte14.087 8 2.900-17.581-28.8699 d+s 5.000-8.451-5 .752 rla 111 s, oo. 8 1.51680 ν9 64, 20 17 Valve L1 lC r6 : ε=O,100OOX 10 Aa;-0,19345X 10-" As knee 0.14283X 1O-7 A*;-0,45281X 10-' r+s : ε=O,100OOX 10 A,=-0,13108X 10 Aa=-0,13460x 10 As=0.25100X 10 rla : ε;0.100OOX 10A,=-
0,11599X 10 A6=0.25408X 1O-6 As: 0.12g45X 10-'<Example3> f = 52.5~19.0~9゜25 F xa
= 2.22~1.63~1.631 30.750 d+・4.60O 5 1,77250 49,77 −46,108 r5: r+ll: r+-: ε=O, 100OOX 10 A, ~0.11251X 1O-3 As=-0,32466X 10-' A*=-0,12421x 10-" ε=O,100OOX 10 A,=-0,14130X 10-' Aa=-0,43112X 10-' A@= -0.41377X 10-" ε=O, 100OOX 10 A, =-0,10531X 10-" Ae=0.21219x 1O-6 As"0.55010X 10-'<Example4> f=52.5~ 19.0~9.25 F true◇=2.
23 ~ 1.63 ~ 1.631 Tsuyoshi fLjuJro old' Milk Riken Eyusa 117 Ben U Mason 1shir7: ε=0.10000×10 A4=0.12378X 1O-3 Ae;0.92400X 1O -7 At=o, 14925X 10-' r+@: ε=0.10000X 10Aa=-0
, 18404 .89459X 10-” <Example 5> f=52.5~19.0~9.25 FNO=2.2
2~1.63~1.634 29.718~14.232~2.000r 77.170 6 3,700 7 80.775 8 1.400~16.88f3~29.1189 (Ls 5.000~ 8.055~5.511 r16 0d+e 5.000 Ns 1.51680 Vs
r17 c. Valve IJJJL re: ε=o, 1ooooox 10A, =-0
, 11066X10-' Aa=0.44095X 10-' [email protected] 10-' r,,: s =0.10000X 10A4=0.
41741X 10-4 64, 20 Ae=-0,20002x 1O-a A@=0.79117x 10-' r, 6: ε:o, 10000X10A, =0.
50386x 10" As=0.34063X 10-' As=-0.13662x 10-8 <Example 6> f=52.5~19.0~9.25 F no=2.
22~1.63~1.631'' (Vine Thief-1uJ Jitsu 1
Emperor Eyusa 16 8.475 6 3.700 r8* 92.584 d volume 1.400~16.808~29.005r Kan-ya 17.203 a+i 4.50O 5 1,77250 ν5 49.77 r11 68.860 l1 5.800 rag -30,119 dos 5.000~ 7.638~ 4.975 rHl 00 Valve J11 1 re: s =O, 100OOX 10A4=-
0,11191X 1O-3 As=0.51106X 10-'As"-0,22458X 1O-7 r+I: e =O,100OOX 10A4=
0.24628×10-' Aa: 0.35278X 1O-7 As=-0,15477x 10-" rag: ε=0.100OOX 10Aa=0
．． 93491x 10-' A6=0.24719X 10"As=-0,24013xlO-"<Example7> f=52.5~19.0~9.25 F No =
2.21-1.63 ~ 1.63 dishes"" eye i] and L side!
Milk limb vine 22m 1r+ 29.900 d21.400 rs 21.940 4 29.588~14.374~2.0006 3,700 7 67.547 9 8 9 1.400~16.815~28.9885 .200~
2.472-5.092 d lower, 500 re2-191.234 dos 1, 300 14 24.795 dos 5.000-7.728-5.108 rag 18 s, oo. N@ 1.51680 ν8 64, 20 r1 Fuben JLit only JL re: ε=o, 1oooooxi. Aa;-0,11201X 1O-3 As;-0,12401X 10-'As''-0,20029X10-' rth: ε=O, 100OOX 10A, = 0.46
016X 10-' Aa=0.15437x 1O-7 A@=0.44240X 10-' r+s: ε=o, 10000X10A, =0.
22600X 10-'Aa"0.10442X10-'As; 0.95730X 10"<Example8> f=52.5-19.0-9.25 FNo=2.2
1-1.63-1.635 1.20O 3 1,77250 49,77 6 8,453 6 3,700 65,493 8 1,400-16.791-28.9989 d+45.000-7.721- 5.095 re5 oO d, 6 5.000 N, 1.5168 Or,,
00 valve] Ju wound 1 rs : s :O, 100OOX 10A, =-
0,10906X 1O-3 Aa=-0,14505X 1 leaf 6 As=-0,18237x 1 leaf 7 r+I: 6 =0.100OOX 10A4=
0.39760x 10-' As=0.44990x 10-'As;0.67384X10-' 64.20 rIJ: ε20.10000×10A4=0.47
188X 10-"Aa; 0.13754X 10-' A, = -0,22440X1 leaf 9 <Example 9> f=52.5~19.0~9.25 FNO=2.4
2～1.63～1.831Supervisor IJLJLu口 Former LI
T! Volume 11 1d21.300 3 19.881 3 5.000 N21.71300 ν253.9
3 4 -687.649 4 25.463~11.793~2.000s 54.429 8 2.000~18.670~31.462rts Book 13.743 d+s 5,50O 5 1,67000 57,07 r+2 - 27.284 d+2 1,30O 6 1,80518 25,43 r+4 pieces 22.891 r17 o. Valve' u1 Yogi JL r6: ε=O, 100OOX 10Aa=-0,2
2871
-0, 19353 As"-0,37355X 10-"<Example10> f=52.5~19.0~9.25 FNO=2.2
4-1.63-1.63 Sarabe lso LJLIJ 吋罎 糺L! 22 balls 16 3.300 17 Valve JiL 1L r6: ε=0.10000x 10 A4=-0,30807X 10 Bow Ae=-0,16100X 10 A8=-0,55189X 10 r, @: ε:0. 10000×1OA4=-0,2
3193X10Ae=-0,10895X10A,=-0,26703x10r,4: ε:0.10000×10Aa=-0,1
3036x 10 As: 0.21448X 1O-7 As = 0.12126X 10-'<Example11> f = 52.5-23.0-9.25 F. =2.2
2 ~ 1.63 ~ 1.63 negative''(Modan,]U''ji(''
L vine 11 volumes 17 1.90O 4 1,84666 23,82 dos 5.000~ 8.573~ 5.480 rl 7 (X) Valve n section 1 re: t: :O, 100OOX 10Aa knee 0.10808X 10 -” Ae=o, 10462X 1O-7 As=J. 19798X 10-” r+l: ε=O, 1oooox 10A, =0
．． 33515X 10-' Aa=-0,10359X 1 leaf 7 A,=0.18918X 10-' r+z: g=o, 10000X10A4"0.
72402X 1O-4 Aa=-0,35959X 10-' A*=-0,19113X 10-"<Example12> f-52,4~16.0~9.25 FNO=2.1
6～1.63～1.6311(Adan-JuJ口υ[Mitsuuritsune Yuki1r2 20.315 6 7 13.913 7 2,500 3.400 Nii1.84666 shi4 23.82 9 9 rl -81,878 rl2 12.759 rl3 57.935 r+a-222,389 5,800~ 3.737~ 5.715 0.100 4.000 N6 0,700 3.200 N7 1.77250 1.80518 Shirosifu 49.77 25.43 15 9, 752 dos 5.000 Hm 1.51880 64.20 rl9 00 valve'yo111shira: ε:0.100OOX 10Aa"-0
, 14724X 1O-3 A6=0.39708x 10-6 10-6A, 40940X 10-' r17: ε=o, tooooox 10Aa"0
．． 66529x 1O-5 Aa: 0.47942X 10-" As=-0,12138X 10-"<Example13> f=52.5-19.0-9.25 F) 10 =
2.26~1.63~1.633 5.100 2 1.71300 53.93 ra -518,546 rs 18.256 r8 city 8.438 rv 12.788 ra 22.140 rg 00 r+s 17.606 27 .781~13.608~2.0001.100
N3 1.77250 ν. 2.100 3.000 N, 1.8466fli ν42
．． 900~17.073~28.6816, Zoo~
2.550~5.10649.77 23,82 rl2 -16.748 rl3 24.715 r+a 147.895 r+s -35,094 rl6 books 23.471 r+v 41.402 l8CxI ric. Valve first: ε:O, 1oooox 10A, =-0,
14744X 10-3 A, =-0,33281
VQfly 5.000~8.550~5.994d
ls s, ooo Me 1.516g (l
v. 1.80518 1.69100 ν6 ν) 25, 43 54.75 53.93 64, 20 A*=-0,39797X 10-' r+s: e"0°100OOX 10Aa knee 0.50770X 10-' Aa=0. 82764x 1O-7 A*knee 0.26199X 10-” <Example 14> f=52.5~19.0~9.25 FNO=2.2
1~1.83~1.631!41 11!
1ヱmu1r2 19.813 d21.400 T 55.633 7 1.90O 4 1,84666 C4 23.82 9 5.200~ 2.376~ 4.956 r11$-46,597 dth 6,700 rt2 98.701 12 6,30O 6 1,61800 White 63.39 rt: ε=0.10000X 10Aa=-0,
10644x 10-"As" 0.44401X 10-'As=-0,1
1411X 10-' r+I: t =0.10000x 10A4=
0.23136X 1O-4 Ae: 0.31636X 10-' A*=-0.57650X 10-" r, 4: ε=O, 100OOX 10A4=0.7
1539X 1O-6 Ae=-0,20593X 10-' As=-0,44352X 10-'<Example15> f=52.5-19.0-9.25 FNO=2.2
5~1.63~1.6331!141 1
JI vine L Yube 1rl 30.622 1 1.500 N, 1.84666shi 1 23.82 r, umbrella 21.854 3 r--326,475 4 r5 -as, 938 as re book 8.681 6 r7 14 .632 7 re 30.822 d@ rll 00 9 rllll umbrella 15.487 d+@ 5.300 N2 1゜71300 ν253.
9327.940~13.286~2.0001.10
0 Ns 1.77250 νg 49.7
72.100 3.000 N4 1.84666 νa 2
3.822.900~17.554~28.8406.
100~2.456~5.108 4.500 Ns 1.77250 νs
49.77 (La r+a umbrella 23.352 (La rt5-15.097 I5 r+s (1) d+5 rt7 (1) Valve 1 [L grandson 1 r3: t = O, 100OOX 10A4 = 0
．． 25437X 10-11 1.800 4.300 Nv 1.71300 Schiff5.
000~8.644~5.992 5.000 Ng 1.51680 ν. 53.93 64.20 Ae=-0,24898X 1O-9 A,=0.28161X 10-1"re: ε=O,100OOX 10A,=-0
, 19880X 1inch3 Ae=0.35981X 1O-6 As=-0,43102X 1O-7 r,ll: ε=0.10000×1OA,=-0.
14843X 10-' Aa=-0.17778X 1O-6 All=0.44457x 10-" r, 4: ε=O, 100OOX 10A, =-0,
1271ex 1O-3 A6=0.31969X 10-' As=0.50205x 10-9 <Example 16> f=52.5-20.0-9.25 Fxo=2.34-1.63-1. 631 Remains” So IJJ
JI old "A" mouth Σ number d+a 1.600 d+v 4, υ0υ 9 1, ri16δU ν9 64, iυ r18'') Valve] 1 [Grandchild 1 rs: ε=0.10000X10A, =-0.
19527X 1O-4 Ae=-0, 10374X10-' As: 0.11782X 10-" r7.: ε=0.100QOX 10Aa=-0,
21619X 10-' Aa knee 0.43525X 10-' As =-0,82218X 1 inch. r+s: g=o, 10000X10Aa"-0
, 11658X 10-" Ae=0.14494X 10-' As: 0.75439X 10-" FIGS. 1 to 16 are lens configuration diagrams corresponding to Examples 1 to 16, respectively, and the arrows in the figures (1), (2
) and (3) schematically show the movement of the first group (■), second group (It), and third group (m) from the telephoto end (T) to the wide end (w). There is an aperture (A) between the second group (II) and the third group (III).
) is provided. In addition, aberrations are corrected by inserting a flat plate (P) corresponding to a low-pass filter or a face plate at the end of the lens. In either embodiment, when changing the magnification from the telephoto end to the wide end, the second group moves toward the object side on the optical axis, and the third group moves toward the object side and then makes a U-turn on the way. Draw a trajectory. Further, in Examples 1 to 8, and 11 to 16, the first group does not move, and in Examples 9 and 10, the first group moves toward the object side and the image side, respectively. In Examples 1 to 11, the first group and the second group each had two sheets,
The third group consists of three lenses, a positive lens, a negative lens, and a positive lens from the object side, for a total of seven lenses. Of these, in Example 11, the third group consists of a front group with one positive lens, a negative lens, and a rear group of positive lenses from the object side, and the relative positions of the front and rear groups are slightly changed during zooming (arrow (4) )) This is an embodiment of a type with a floating function. In Examples 12 and 13, the first group and the second group each have two lenses, and the third group has four lenses: a positive lens from the object side, a positive lens, a negative lens with a strong refractive surface facing the image side, and a positive lens. Similarly, the third group is made up of four lenses from the object side: a positive lens, a biconcave negative lens, a positive lens, and a positive lens, for a total of eight lenses. In the fourteenth embodiment, the first group and the second group each have two lenses, and the third group has three lenses from the object side: a positive lens, a positive lens, and a negative lens, for a total of seven lenses. In Examples 1 to 14 described above, aspheric surfaces are used for the second group and the third group. Example 15 has a similar configuration to Example 1, but also includes an aspherical surface in the first group to improve performance. In Example 16, the first group has two sheets and the second group has three sheets. The third group consists of three lenses, for a total of eight lenses. Furthermore, aspherical surfaces are used for the second and third groups. The aspherical surface used in the present invention may be formed by directly pressing or reprocessing glass material, or may be formed by pasting together a thin aspherical resin layer. FIG. 32 is an aberration diagram corresponding to each of Examples 1 to 16, in which (a) shows the focal length at the telephoto end, and (b) shows the middle focal length. (C) shows aberrations at the focal length at the wide end. Also, the solid line (d) represents the aberration for the d-line, and the dotted line (
SC) represents the sine condition. Furthermore, the dotted line (DM) and the solid line (
DS) represents astigmatism on the meridional plane and the sagittal plane, respectively. As described above, since the above embodiment has a high zoom ratio of 6x and a large aperture ratio of Fl, 6, it is possible to use a simple three-group system with a small number of elements, only 7 to 8 elements in the entire system. In addition to achieving sufficient aberration performance, the overall length and outer diameter of the front lens are also quite compact, and the desired objective of the present invention is fully achieved. As explained above, according to the present invention, it is possible to realize a variable power lens that has a high variable power ratio and a large aperture ratio, and is compact, low cost, and has high performance in terms of aberrations. Can be done. In particular, by effectively using aspheric surfaces in the 3-group system, which is more advantageous for downsizing and reducing the number of lenses, a bright variable magnification lens with a variable power ratio of about 6x and FIIO of about 1.6 can be produced with high performance. This can be achieved while maintaining the

[Brief explanation of drawings]

Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6,
Figures 7, 8, 9, 10, 11, 12, 13, 14, 15, and 16
The figures are lens configuration diagrams corresponding to Examples 1 to 16 of the present invention, respectively. Figure 17, Figure 18, Figure 19, Figure 20,
5s21 figure, figure 22, figure 23, figure 24,
Fig. 25, Fig. 26, Fig. 27, Fig. 28, Fig. 29. FIG. 30, FIG. 31, and FIG. 32 are aberration diagrams corresponding to Examples 1 to 16 of the present invention, respectively. Fig. Fig. Fig. 3 Fig. Fig. Fig. 5 Fig. Fig. 7 Fig. Fig. Fig. Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16

Claims (1)

Scope of Claims: (1) Consisting of three groups in order from the object side: a first group having a positive refractive power, a second group having a negative refractive power, and a third group having a positive refractive power; The first group includes one high dispersion negative lens and at least one positive lens, and the second group includes one high dispersion positive lens and at least one negative lens, and the second group includes one high dispersion positive lens and at least one negative lens. The third group is composed of three or less lenses, and the third group is configured to include at least one high dispersion negative lens and one or two positive lens components on the object side of the high dispersion negative lens; A variable power lens characterized in that the group and the third group have aspherical surfaces and move on the optical axis during zooming. (2) The number of high dispersion negative lenses in the third group is one, and the third group is composed of a total of five or less lenses, and
The variable magnification lens according to claim 1, characterized in that the group and the second group satisfy the following conditions; 0.20<φ I /|φ II | <0.31, where φ I :th Combined refractive power of the first group φII: This is the combined refractive power of the second group. (3) A second lens unit characterized in that the first group is composed of two lenses: a negative meniscus lens convex toward the object side and a positive lens with a strong surface facing the object side, and satisfies the following conditions.
Variable power lens according to claims; ν_2−ν_1>22 where: ν_1: Abbe number of the negative meniscus lens with respect to the d-line ν_2: Abbe number of the positive lens with respect to the d-line. (4) The third group consists of one or two positive lenses, a negative lens, and one or two positive lenses in order from the object side, and the third group has three or four lenses in total. A variable power lens according to claim 3, characterized in that it is comprised of: (5) The variable magnification lens according to claim 4, characterized in that a diaphragm is disposed between the second group and the third group. (6) a negative lens in which the second group has a strong surface facing the image side;
The variable magnification lens according to claim 4, comprising a positive lens spaced apart from the negative lens, and satisfying the following condition: -0.4<r_6/r_7<
1.0 ν_3-ν_4>16 where, r_6: Paraxial radius of curvature of the image side surface of the negative lens in the second group r_7: Paraxial radius of curvature ν_3 of the object side surface of the positive lens in the second group : Abbe number of the negative lens in the second group for the d-line ν_4: Abbe number of the positive lens in the second group for the d-line. (7) The variable magnification lens according to claim 6, wherein the third group is composed of three lenses: a positive lens, a negative lens, and a positive lens in order from the object side. (8) The third group consists of, in order from the object side, a positive lens, a positive lens, a negative lens with a strong refractive surface facing the image side, and a positive lens.
The variable power lens according to claim 6, characterized in that it is composed of a single lens. (9) The variable magnification according to claim 6, wherein the third group is composed of four lenses: a positive lens, a biconcave negative lens, a positive lens, and a positive lens in order from the object side. lens. (10) When changing magnification, there are two groups that move: the second group and the third group. When changing magnification from the telephoto end to the wide end, the third group moves toward the object side and makes a U-turn midway. The variable magnification lens according to claim 2, characterized in that the variable magnification lens draws a trajectory that follows the curve. (11) The variable power lens according to claim 10, wherein the third group also serves as a focusing lens. (12) The third group is also used as a focusing lens, and has a floating function that divides the third group into several small groups and minutely changes their relative positions during focusing. A variable power lens according to claim 6. (13) The variable magnification lens according to claim 6, wherein the third group is divided into several small groups, and the relative positions of these groups are slightly varied during variable magnification. (14) The variable magnification lens according to claim 6, which satisfies the following conditions: fw·φ I >0.15, where fw is the combined focal length of the entire system at the wide end. (15) The variable magnification lens according to claim 3, wherein the third group is composed of a total of three lenses, two positive lenses and one negative lens in order from the object side. (16) The second group is composed of two lenses: a negative lens with a strong refractive surface facing the image side, and a positive lens arranged with a space from the negative lens. A variable power lens according to claim 15. (17) The variable power lens according to claim 3, wherein the first group has at least one aspherical surface. (18) The second group is composed of two lenses: a negative lens with a strong refractive surface facing the image side, and a positive lens arranged with a space from the negative lens. A variable power lens according to claim 17. (19) The variable power lens according to claim 18, wherein the third group is composed of three or four lenses.