JPH04208912A - High magnifying power zoom lens - Google Patents

Abstract

PURPOSE:To offer a high performance zoom lens including a wide-angle and having a specific zoom variable power rate and an F-number by adopting an extremely simple lens configuration for a second lens group G2 having negative first and second lens components G21 and G22, and a positive third lens component G23, in order form an object side. CONSTITUTION:In a zoom lens composed of the four groups of the positive, the negative, the positive, and the positive, the lens group G2 has the negative first and second lens components G21 and G22 and the positive third lens component G23, in the order from the object side. When variable power from a wide- angle end to a telephoto end is carried out, the lens groups G1, G3, and G4 are individually moved to the object side and the following conditions are satisfied; (1)-3<=fG2.hG2R/fT<=-2(2)5<=fG3.hG3F/FT<=9(3)10.3<=fG4.hG3F/fT<=25, where, fT is the focal distance of all systems on the telephoto end, fG2, fG3, and fG4 are the focal distances of the lens groups G2, G3, and G4, and hG2R, hG3F, and hG4F are the height of the ray of light from an object point at infinite on an axis, from a position where the light passes the most image sides of the lens groups G2, G3, and G4, or the most peripheral edge of the surface of the object side, to an axis.

Description

[Detailed description of the invention]

[00011

[Industrial Application Field] The present invention includes a wide angle of view with a maximum angle of view exceeding 60°, has a relatively wide variable magnification range from so-called wide-angle to semi-telephoto, and has an aperture of approximately F2.8. This relates to zoom lenses. [0002] [Prior Art] In recent years, lenses with a zoom ratio of about 3x and one end of the zoom range on the wide-angle side have an F number of F3.5.
Various lenses have been proposed that are darker than the above. For example, JP-A-55-62419, JP-A-56-114920
No. 2, etc. are known. Also, in this type of zoom lens, the one that achieved a large aperture was the
Publication No. 19 is known. [0003]

[Problem to be solved by the invention] The above-mentioned Japanese Unexamined Patent Application Publication No. 1983-1989
The zoom lenses proposed in No. 419 and Japanese Unexamined Patent Publication No. 114920/1980 are both zoom lenses having four groups of positive, negative, positive, and positive, and are designed to have relatively high magnification. However, the aperture ratio is relatively small due to the shape of the second lens group and the refractive power arrangement of each group. Furthermore, since sufficient aberration correction has not been performed, the imaging performance is poor, and in particular, significant fluctuation forces due to zooming due to field curvature, astigmatism, and coma aberration remain. Furthermore, although the F-number is small and the lens is dark at maximum aperture, the correction of spherical aberration at the telephoto end was not sufficient. Furthermore, the overall size of the system was too large for its caliber and could not be called compact. Therefore, if the refractive power is arranged in this state and the aperture is increased, the degree of freedom in correcting aberrations will be further insufficient, and at the same time, each lens component will interfere with each other, making it difficult to realize the lens. [0004] Furthermore, Japanese Patent Publication No. 46-43019 is known as the only zoom lens of this type that achieves a large aperture ratio of approximately F2.8 with an F number at full aperture over the entire zoom range. However, even in this zoom lens, the correction of off-axis aberrations is insufficient, and in particular, the fluctuation of coma aberration due to zooming is large (and it is difficult to put it into practical use as it is. [0005] Therefore, the present invention solves the above problems,
The object of the present invention is to provide a high-performance zoom lens that includes a wide angle, has a zoom ratio of about 3 times, and has an F number of about F248. [0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a first lens group G1 having a positive refractive power and a first lens group G1 having a negative refractive power in order from the object side, as shown in FIG. a second lens group O2 having a positive refractive power; and a third lens group O2 having a positive refractive power.
a lens group G3 and a fourth lens group G4 having positive refractive power
The second lens group O2 has, in order from the object side:
A first lens component G21 is made of a single lens or a cemented lens and has a negative refractive power; a second lens component G22 is made of a single lens or a cemented lens and has a negative refractive power; and a second lens component G22 is made of a cemented lens and has a positive refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group G1, the third lens group G3, and the fourth lens group G4 each move toward the object side, and the following conditions are met. It is designed to satisfy the following. (1) −3≦fG2・hG2! I/f d ≦-2 (
2) 5≦fG+・hcu /ft≦9(3) 10
．． 3≦fG4・hG4p / ft≦25 However, fT:
Focal length of the entire system at the telephoto end, fG2: Focal length of the second lens group O2, fG3: Focal length of the third lens group G3, fG. : Focal length of the fourth lens group G4, hc2a
: Height of the ray from the position where the ray from the object point at infinity on the axis passes through the outermost edge of the image-side surface of the second lens group O2 to the optical axis at the telephoto end, hc3F: Infinity on the axis at the telephoto end The height of the ray of light from the far object point to the optical axis from the position where the ray of light passes through the outermost edge of the surface closest to the object of the third lens group G3, hcu: The height of the ray of light from the object point at infinity on the axis at the telephoto end This is the height of the light ray from the position passing through the outermost edge of the surface closest to the object side of the fourth lens group G4 to the optical axis. [00071 Based on the above basic configuration, it is more preferable that the second lens group O2 includes an aspheric surface that satisfies the following conditions. (4) 0.0008≦lAs-3/fw≦0.05
However, fw is the focal length of the entire system at the wide-angle end, and AS-3 is the difference in the optical axis direction between the aspherical surface and a reference spherical surface having a predetermined apex radius of curvature at the outermost periphery of the effective diameter. [0008]

[Function] In general, zoom lenses that have a positive, negative, positive, and positive 4-group configuration, especially standard zoom lenses with a variable magnification ratio of about 3x, have an open F number of F3.5 to F5.6 class zoom lenses. is the mainstream, and as in the present invention, open F
Very few lenses have been proposed with a number of around F2.8 over the entire zoom range. [0009] Generally, the second lens group O2 of this type of zoom lens plays a large role mainly in correcting off-axis aberrations at the wide-angle end. However, in order to increase the aperture of this zoom lens as it is, it imposes a large burden not only on off-axis aberrations on the wide-angle side, but also on axial aberrations on the telephoto side. In particular, it becomes more difficult to correct spherical aberration and lower coma on the telephoto side, and the burden of aberration correction on the second lens group increases. Therefore, among the degrees of freedom for correcting aberrations of the second lens group O2, if the contribution rate to spherical aberration and lower coma at the telephoto end is increased, distortion at the wide-angle side,
Correction of aberrations such as field curvature and astigmatism becomes insufficient. [00101] Therefore, in the present invention, in order to overcome this problem, we have discovered the optimal configuration of the second lens group G2 and its optimal refractive power arrangement. That is, in the present invention,
The second lens group O2 has, in order from the object side, a negative first lens component G21, a negative second lens component G22, and a positive third lens component G23 made of a cemented positive lens and a negative lens. Even with this lens configuration, the optimal refractive power arrangement effectively corrects off-axis aberrations such as astigmatism, field curvature, downward coma, and distortion at the wide-angle end, and further corrects spherical aberration and downward distortion at the telephoto end. This makes it possible to effectively correct coma aberration. [00111 Therefore, in order to make the second lens group O2 function well in correcting the above-mentioned aberrations and to obtain excellent imaging performance while configuring the entire lens system with a small number of lenses, only the second lens group O2 is required. Therefore, it is extremely important to arrange optimal refractive power in the third lens group G3 and the fourth lens group G4. In addition, in order to realize a large-diameter zoom lens, it is necessary to increase the height from the optical axis of the ray that determines the aperture f-number and the Rand ray (ray from an object point at infinity on the axis) that passes through the highest position of each lens group. It is necessary to make the height higher. The higher the height h, the more the light rays pass through the periphery of the lenses in each group, and therefore the optimum refractive power arrangement is required to be more advantageous in correcting aberrations. [0012] Therefore, in the present invention, optimal conditional expressions (1) to 1 regarding the height h of the Rand ray passing through the highest position in the second to fourth lens groups and the refractive power of the lens groups are
We found (3). In the following, conditional expressions (1) to (3
) will be explained. If the lower limit of conditional expression (1) is exceeded,
In a lens having a constant aperture ratio, the second lens group G
The negative focal length of O2 becomes significantly larger than the focal length of the entire system, and the amount of movement of the second lens group O2 during zooming becomes significantly large. Therefore, in order to obtain a desired variable power ratio, mechanical interference occurs, and the second lens group G2 becomes thicker, making it difficult to make the entire lens system more compact. On the other hand, when the upper limit is exceeded, the negative focal length of the second lens group O2 becomes significantly smaller than the focal length of the entire system. For this reason, especially due to the lack of freedom in correcting aberrations, spherical aberrations on the telephoto side cannot be sufficiently corrected, and fluctuations in spherical aberrations due to zooming also increase. Therefore, when attempting to correct this spherical aberration satisfactorily, the degree of freedom for correcting other aberrations is insufficient, and conversely it becomes difficult to correct lower coma aberration, astigmatism, and curvature of field. Furthermore, as the negative refractive power of the second lens group becomes stronger, the value of the Petzval sum becomes significantly negative, so that fluctuations in field curvature and astigmatism due to zooming become large. Therefore, in order to correct these aberration fluctuations, the number of lens components must be increased, resulting in an increase in the size of the lens system. Note that it is desirable to set the lower limit value of conditional expression (1) to -2, 5 and the upper limit value to -1, 5, and to configure so that the range is satisfied. This makes it possible to achieve a high-magnification zoom lens that is more compact, has better imaging performance, and has a wider angle of view. [00131 When the lower limit of conditional expression (2) is exceeded, the focal length of the third lens group G3 becomes significantly smaller than the focal length of the entire system, and the fluctuation of spherical aberration due to zooming becomes significantly large, especially on the telephoto side. It becomes difficult to correct spherical aberration. If spherical aberration is corrected in this state, the number of lenses constituting the third lens group G3 must be significantly increased, and as a result,
This is not preferable because it makes the lens group more complicated and larger. On the other hand, if the upper limit of conditional expression (2) is exceeded, the third lens group G
Since the focal length of G3 is significantly larger than the focal length of the entire system, it is advantageous in terms of correcting various aberrations, but it not only leads to an increase in the size (thickness) of the third lens group G3, but also increases the focal length due to zooming. The amount of movement of the third lens group G3 increases, and as a result,
This is undesirable as it increases the size of the entire system. Furthermore, conditional expression (2)
It is more desirable to set the lower limit value of 5.7 and the upper limit value 8.5, and to configure the structure so as to satisfy these ranges. This makes it possible to achieve a high-magnification zoom lens that is more compact, has better imaging performance, and has a wider angle of view. [0014] When the lower limit of conditional expression (3) is exceeded, the focal length of the fourth lens group G4 becomes significantly smaller than the focal length of the entire system. Particularly in the case of a fast zoom lens, the degree of freedom to correct each aberration is significantly reduced, and especially at the wide-angle end, variations in upper coma aberration, field curvature, and astigmatism due to 7 magnification changes become significant. The spherical aberration also worsens. Further, in order to correct aberrations in this state, the fourth lens group G4 becomes undesirably complicated and large. On the other hand, if the upper limit of conditional expression (3) is exceeded, the focal length of the entire system becomes 4th
The focal length of lens group G4 becomes significantly large. This not only leads to an increase in the size of the fourth lens group G4 and the diameter of the rear lens of this lens group, but also increases the size of the fourth lens group G4 for zooming.
This is not preferable because the amount of movement of the lens group G4 increases, resulting in an increase in the size of the entire system. Note that in order to obtain more compact size and better imaging performance, it is desirable to set the upper limit of conditional expression (3) to 20 and to configure the structure so that this range is satisfied. [0015] Now, while aiming for a large aperture ratio and compactness by using a small number of lenses in the second lens group,
In order to obtain better imaging performance in all zoom ranges, it is effective to provide an aspherical surface in the second lens group. This makes it possible to significantly improve the degree of freedom in correcting off-axis aberrations, particularly variations in field curvature, distortion, and lower coma due to zooming. [0016] In this case, it is more desirable to satisfy the following conditional expression (4). (4) 0.0008≦lAs|/fw≦0.05, where fw: focal length of the entire system at the wide-angle end, AS-3: reference having the aspherical surface at the outermost periphery of the effective diameter and a predetermined vertex radius of curvature This is the difference in the optical axis direction from the spherical surface. [00171 Conditional expression (4) is a condition regarding the effect of the aspheric surface in the second lens group. This aspherical surface particularly functions effectively to correct lower coma aberration at the wide-angle end, fluctuations in lower coma aberration due to zooming, and spherical aberration at the telephoto end. For this reason, conditional expression (4) defines the optimal shape of the aspheric surface in order to sufficiently obtain the correction effect. Conditional expression (
If the lower limit of 4) is exceeded, especially in the case of a large-diameter zoom lens, the effect of the aspheric surface will be significantly reduced, and the effect of correcting the fluctuation of lower coma aberration due to zooming and the lower coma aberration on the wide-angle side will be reduced. Furthermore, the effect of correcting spherical aberration on the telephoto side is significantly reduced, making it difficult to correct, and the effect of the aspheric surface is lost. On the other hand, when the upper limit of conditional expression (4) is exceeded, higher-order aberrations occur, resulting in significant fluctuations in comatic aberration due to fluctuations in the angle of view, and it becomes difficult to manufacture aspherical surfaces. In addition, in order to obtain an aspherical surface that is easy to manufacture and can reduce costs while effectively obtaining the effects of an aspherical surface, the upper limit of conditional expression (4) is set to 0.03.
It is more preferable to configure the structure so as to satisfy this range. [0018] Furthermore, in order to achieve more sufficient aberration correction, it is more desirable to satisfy the following conditional expression (5). (5) 1.7≦fGl/f−≦2.55, however, f
G+: Focal length of the 41521 group G1, fw: Focal length of the entire system at the wide-angle end. [00191 Conditional expression (5) defines the appropriate refractive power of the 41521 group G1. When the lower limit of conditional expression (5) is exceeded, it becomes difficult to correct fluctuations due to zooming, such as spherical aberration and lower coma aberration, especially on the telephoto side. For this reason, if an attempt is made to correct these aberration fluctuations, the number of lenses constituting the second lens component will increase, resulting in an undesirable increase in the size and cost of the lens system. On the other hand, if the upper limit of conditional expression (5) is exceeded, the refractive power of the 41521 group G1 becomes weaker,
The amount of movement of the 41521 group G1 during zooming increases. For this reason, on the telephoto side, the principal ray passes more through the lens periphery of the 41521 group G1, leading to an increase in the diameter of the front lens, leading to an increase in the size of the lens system. Furthermore, the lens barrel that holds the lens system becomes larger, and problems such as eccentricity make it difficult to design the lens barrel. [00201 In this way, if the conditional expression (5) is satisfied, the 41521 group G1 is cemented to a positive lens, as can be seen from FIG. It is possible to basically configure the lens with three lenses: a cemented positive lens consisting of a negative lens, and a positive lens. As described above, in the present invention, the second lens group includes, in order from the object side, a negative first lens component G21, a negative second lens component G22, and a positive third lens component made of a cemented positive lens and a negative lens. By having a configuration including lens component G23, it functions to satisfactorily correct off-axis aberrations such as astigmatism, field curvature, downward coma, and distortion at the wide-angle end,
At the telephoto end, it is now possible to significantly correct spherical aberration and downward coma. In order to maximize the effect of correcting these aberrations, the third lens component G23 of the cemented positive lens in the second lens group O2 is composed of, in order from the object side, a positive lens and a negative lens cemented to this. More preferably, the following conditional expressions (6) to (9) are satisfied. (6) 2.5≦fG2* / l fGz l
≦5.5 (7) O<QG2R/hc2i≦0
．． 15(8) 0.18 /FN T ≦D/
ft≦0.35/FN(9) 0.09≦n
2n n2p≦0.22 However, fG+++: 2nd
Third lens component G having positive refractive power in lens group O2
Focal length of 23, QO2+1: The radius of curvature of the surface closest to the object in the third lens component G23 having positive refractive power in the second lens group G2 is r, and the radius of curvature of the surface closest to the image is rs. When, QG2R= (rs +rx) / (r+-r
A), D: center thickness of the positive lens located on the object side of the third lens component G23 having positive refractive power in the second lens group O2, FNr: F when opened at the telephoto end
Number hc+*: Height (mm) of the ray from the position where the ray from the object point at infinity on the axis passes through the outermost edge of the image-side surface of the second lens group G2 to the optical axis at the telephoto end, n2ゎ142221 The third group with positive refractive power in O2
The d-line (587,6 nm) of the negative lens in lens component G23
), n2p: d-line (587, 6n
m) is the refractive index. [00211 Conditional expressions (6) to (9) are the second lens group O2
Cemented lens with positive refractive power (third lens component)
It stipulates various conditions regarding G23. As mentioned above, the configuration of the second lens group G2 is extremely important in order to fully exhibit the effects of the present invention, and in particular, the cemented lens G23 with positive refractive power is suitable for use with a bright zoom lens. They play an important role in making this a reality. [00221 Conditional expression (6) is a cemented lens (third lens component) with positive refractive power for the focal length of the second lens group O2
This shows the relationship between the optimum ratios of the focal lengths of G23. As described above, this cemented lens G23 greatly contributes particularly to correction of spherical aberration fluctuations due to zooming, correction of spherical aberration on the telephoto side, and correction of lower coma aberration. Therefore, it is necessary to arrange the optimal refractive power of the cemented positive lens G23 with respect to the second lens group O2. When the lower limit of conditional expression (6) is exceeded, the refractive power of the cemented positive lens G23 becomes strong, making it difficult to correct spherical aberration, especially on the telephoto side. As a result, the second
Since the refractive power of the negative lens components G21 and G22 in the lens group O2 also increases, the balance of off-axis aberration correction is also greatly disrupted, and fluctuations in distortion aberration and lower coma aberration, especially on the wide-angle side,
The variation in field curvature becomes significant. On the other hand, if the upper limit of conditional expression (6) is exceeded, the refractive power of the cemented positive lens G23 becomes weak, making it difficult to correct spherical aberration on the telephoto side.
Furthermore, the value of the Petzval sum also moves significantly in the negative direction,
Astigmatism also worsens. Furthermore, the balance of chromatic aberration correction in the second lens group is lost, and variations in lateral chromatic aberration and the like become significant. Further, in order to obtain a sufficient effect of aberration correction by the cemented positive lens G23, it is desirable that the lower limit of conditional expression (6) be 3.15, and the configuration be such that this range is satisfied. [0023] Condition (7) is a light ray that determines the open F-number behind the second lens group O2, which is necessary to realize a bright zoom lens, that is, the outermost edge of the second lens group O2 at the most image side. The height hG of the axial ray at infinity passing through
This is a condition indicating an optimal relationship between 2R and the shape of the cemented positive lens (third lens component) G23. The brighter the open F-number, the higher the height hc2* of the axial infinity ray passing through the outermost edge of the image side of the second lens group G2. Pass through the periphery. Therefore, the shape of the cemented positive lens G23 greatly contributes to the correction of spherical aberration on the telephoto side. Further, when the aperture is disposed closer to the image side than the second lens group, the shape of the cemented positive lens G23 relative to the aperture becomes important even at the wide-angle end. [0024] When the lower limit of conditional expression (7) is exceeded, the cemented positive lens G23 changes from a biconvex shape to a shape with a weaker convex surface facing the image side, resulting in field curvature at the wide-angle end and distortion due to zooming. Not only does it become difficult to correct fluctuations in lower coma aberration, but also fluctuations in spherical aberration due to zooming increase, making it difficult to realize a zoom lens with a large aperture and high magnification. On the other hand, the conditional expression (
When the upper limit of 7) is exceeded, the shape of the cemented positive lens G23, which is advantageous for correcting aberrations caused by off-axis rays, takes on a meniscus shape with the convex surface facing the object side, especially at the telephoto end. The degree of freedom in correcting spherical aberration decreases, making it difficult to correct this, which is undesirable. [0025] Conditional expression (8) is a condition that defines the optimal center thickness of the positive lens in the cemented positive lens (third lens component) G23. The center thickness of the positive lens in the cemented positive lens G23 plays an important role in correcting spherical aberration, especially on the telephoto side. Particularly when increasing the aperture, it is necessary to fully utilize the center thickness of this positive lens. If the lower limit of conditional expression (8) is exceeded, not only will it be difficult to correct spherical aberration on the telephoto side, but also the fluctuations in spherical aberration due to zooming will become significant, making it impossible to realize a zoom lens with a large aperture ratio. On the other hand, if the upper limit of conditional expression (8) is exceeded, although it is advantageous for correcting spherical aberration, the second lens group O2 becomes thicker, resulting in an increase in the size of the lens system. [00261 Conditional expression (9) indicates the optimum difference in refractive index between the positive lens and the negative lens that constitute the cemented positive lens (third lens component) G23. When the lower limit of conditional expression (9) is exceeded, it becomes difficult to correct spherical aberration, especially on the telephoto side, and the value of the Petzval sum takes a significantly negative value, resulting in worsening of astigmatism. On the other hand, if the upper limit of conditional expression (9) is exceeded, although it is advantageous for correcting spherical aberration, the Petzval sum takes a significantly large positive value, resulting in worsening of astigmatism. In addition, in order to fully obtain the effect of the optimum difference in refractive index between the positive lens and the negative lens that constitute the cemented positive lens G23G, the lower limit of conditional expression (9) should be set to 0.135. It is more desirable to set the upper limit to 0.2 and configure the structure to satisfy that range. [0027]

Embodiments Next, embodiments according to the present invention will be described. In each embodiment according to the present invention, the focal length f is 36 to 1.
It is a high-power zoom lens that is variable up to O2 and has a wide angle of view with an F number of up to 2.9. In each of the embodiments, for basic fishing, as shown in FIG. 31st/Shizu Group G3 with
and a fourth lens group G4 having positive refractive power.
, is there. When changing the magnification from the wide-angle end to the telephoto end,
-<T, first lens group G]- is linear (@-shaped) toward the object side, and the 21st lens group G] - The cis group O2 moves non-linearly (non-linearly) toward the image side (1st 31/lens group G3 and 4th Ly:, the -z group G4 moves non-linearly (non-linearly) toward the object side). Due to the movement of each 1/cis group due to zooming from the wide-angle end to the telephoto end, the first and second cis group C low and the second L/〉 lens group G
The air distance with 2 is -7 before power increase, the second lens ll'+'E
The air aperture between O2 and the 31st/lens group G3 is reduced 7, and the air gap between the 31st/lens group G3 and the fourth lens group G4 is reduced. [00283 Next, each $ example will be explained and explained. Example 1
In the zoom lens shown in Fig. 1, the positive first
1.・The cis group G1 has a negative smooth casing with its convex surface facing the object side (L-1) and a double convex 1E joined to this.
Izzens Gil and a positive meniscus with the convex surface facing the object side 1. The negative twelfth lens group G2 is composed of a negative lens (first lens component) G21 having a concave surface facing the image side, and a negative lens G21, which has a concave surface facing the image side, and a negative lens G2.・Shiz (second lens component) G2
Bonding pressure 12] consisting of 2 and a negative 1/〉・zu joined to the positive 1/〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉〉》
/Z (third lens component) G23, below LL. Then, ′, the positive 31st. - The cis group G3 consists of a biconvex positive lens G31, a biconvex positive I/lens, and a negative lens cemented to this with a convex surface facing the image side (G32). The positive 41st cis group G4 consists of a biconvex positive lens G41, a positive mascara lens G42 with its convex surface facing the object side, and a negative I/n lens G4.
43, and a positive mascara lens G44 with a convex surface facing the image side.
It is composed of. [0029] The aspherical surface in this example is the 21st.・The negative I/lens G (first lens component) 21 located closest to the object side of the lens group G2 is located on the image side surface (this lens component G), and the fourth lens
It is provided on the image side surface (final surface) of the positive lens G44 located closest to the image side of the cis group G4. In addition, opening 1] Aperture S
is arranged on the object side of the 31st/sys group G3. As shown in FIG. 5, the zoom 1/lens of Example L has basically the same configuration as the zoom 1/> lens of Example 1, but the negative lens in the 21st lens group O2 is The 217th lens component G of
22 is a junction) and becomes 7.°C. , 1 junction negative I/
The lens G22 consists of, in order from the object side, a positive meniscus lens with a convex surface facing the image side, and a first biconcave negative lens cemented to this. (・, i, second shi〉・
It is provided on the image side of the negative l/ns (first tons component) G21 located closest to the object side of the lens group G2, and the fourth
Lens group G4. It is provided on the object side of the positive lens G44 located closest to the image side. These aspherical surfaces are composed of a composite spherical surface (hybrid spherical surface) made of a spherical glass lens and a plastic material. In addition,
The aperture stop ':4 in this embodiment is arranged inside the third L/cis group G3. [0031] Zoom 1 of Example 3.・Figure 10
Examples in the 1st to 31st Nons as shown in
It has the same configuration as the zoom 1/〉・zu (-2, but
The configuration of the fourth lens group G..1 is different. That is, the fourth
The lens group G4 includes a biconvex positive lens G4], a biconvex positive lens G'42, and a negative! It consists of three lenses: / Lens G.13. The aspherical surface in this example is the negative lens (1') located closest to the object side of the 217th lens group.
11th. - lens component) is provided on the object side of G21, and the 41st. Negative 17 located closest to the image side of the cis group
GJ is installed on the object side of the lenses G43. Note that the aperture stop S in this embodiment is arranged on the object side of the third lens group G3. [0032] In each of the embodiments described above, a spherical surface is provided in the first lens group other than the second lens group. It functions effectively to compensate for variations in surface curvature due to magnification, changes in spherical convergence 7, etc. At this time, in order to effectively obtain the effect of an aspheric surface, Conditional expression (
It is desirable to configure the system so that it satisfies (74). Note that it goes without saying that an aspherical surface may be provided in the third lens group. Although it may be placed at any position as long as it is placed at the front end in the center, in order to function more effectively in the correction of off-axis aberrations and to obtain the effect of the present invention on the upper needle, it is necessary to place the aspheric surface 4- at the 21st position as much as possible. /On the object side in O2!/
It is desirable to arrange the lens surface.1. Also, in order to facilitate manufacturing and reduce the aspherical surface in this example, a composite of glass and plastic material There are five models using a spherical surface (Hybrid I7), but it goes without saying that it is also possible to construct an aspherical surface using only glass material.
The values of the specifications and condition-corresponding numerical values of the present invention (4-3 examples) are listed in order. However, the leftmost number represents the order from the object side, and l゛ is 1/ The radius of curvature of the cylindrical surface, d is the distance between 1.lens surfaces, 1] is the Atsube number (1) d), and n is the d-line (λ = 587.6 nm
), f is the focal length of the entire system, and FN is F
Amber and φ represent the aspherical surface I/the effective diameter of the lens. In addition, for the aspherical surface shown in the specification values, the distance along the optical axis direction from the tangent plane of the apex of the aspherical surface at the height y perpendicular to the optical axis is defined as X(lq), and The radius of curvature of the axis is r, the conic coefficient is C, and the n-th aspherical coefficient is C, l.
When, X (h) = (h°/r)/c++
(IKli' / r2)"2] +C2h2+C4h
4+C6h'-1-C8h' (expressed as -C10hlO'. Also, the conic coefficient 1 (and the 11th order aspherical coefficient (E-n at the left end in -2n indicates 10-mouth). [0035] rExample 1] r d ν nl 14
2.768 2.5O23,01,86074273
,4&(12,4070,01518603-280,
849,10 445,3759,0060,71,56384512
4, Seki 2 (mυ 6 418.949 2.0G52.3 1.7
48107 18.477 5.55 8 -51.766 2.0043.4 1.8
40429 76.133. 35 10 33.856 9.0O25,51,7
303811-15,7041,7035,71,90
265 so -41,34I Cat mouth υ13
126.681 4.00 65.8 1.464
5014-97.873, 2015
46.279 11.00 58.9 1.618
2316 -26.974 2.0O23,01
, 8607417-70,750 (catchable 18 59.247 6.5040.9 1.
7963119 -76.390. 1520
30.786 3.9056.0 1. Group 8
8321 66, Beguiled 3.35 22 -102.300 1.85 33.9 1
．． 8038423 29.128 4.30th -13! , 935 3.60 58.9 1.
5182326 -45.970 (B f)
f 36.0000 59.9999 102.0
002d5 3.4087 18.5718 31.
7962d12 20.1182 13.6283
7.5055d17 13.2124 7.0392
3.8684Bf 44.9643 53.73
09 59.9710 Paraxial radius of curvature based on the 7th surface (aspherical surface): r=18.477 Conic coefficient: k・1 Aspherical coefficient C2= 0. C4=-0, 1729E-05, C6=
-0,4735E-07, C8=0.3062E-0
9C10=-0,2365E-11 24th surface (aspherical surface) Standard paraxial radius of curvature: r=-124,935 Conic coefficient: k・I C2=0, C4=-0,9195E-05, C6=- 0
, 2412E-07, C8= 0.1272B-09C
10=-0,4185B-12fG2・hczi/
ft = -2,04fG3・hc3p / ft =
7.64fG<・hc4p/fton=12
．． 371 AS-S l / f w = 0.00
275...7th surface (φ=21°fG1/fw
=2.44 fG2a/l fG21 =4.25QG2R/
hczi =0.0714D/ f t =0.08
82...FN T =2.9n2e
n2p=0.172 [0036]

[Example 2] r d ν n 1 160.001 2.2O23,01,86
074277, 2541L, 50 70.0 1518
603-264.690. 10 4 46.775 g, 5060.1 1.6
20415 Hill 1.025 (mυ 6 829.431 L7G 52.3
L748107 22.000. 0355.9
1.497128 19.522 5.56 9 -68.286 2.5G35.5 L5
950710 -31.061 1.7045.
4 17966811 62, m , 35 12 34.730 9.0027.8 1.6
991113 -14.755 L, 7039
．． 8 18699414 -292.136 (
Circumference 16 94.290 4.3065.8 1.
4645016 -100. α)1 3.0017
46.323 10.30 58.9 L 8
2318 -27.173 2.0O23,01,
8607419-77,467 (iii mouth 20 57.255 6.0G40.9 L7
963121 -75.244. 15 22 30.552 3.9056.0 1.5
688323 88.801 3.35 24 -97.793 1.8533.9 L uncle■μ25 2B, 8 4.80 26 -80.760 . 0665.9 1.4
971227-70. αc 2.50 58.
9 15182328 -50.329 (B
f) f 35.9999 60.0000 102
．． 0008d5 4.0893 19.2524 32
．． 4768d14 18,1&(211,64&1
5.5205d19 15.9310 9.7578
6.6870bf 43.1230 5L889
7 5B, 1296 8th surface (aspherical surface) Standard paraxial radius of curvature: I'・19.522 Conic coefficient: k
・1 Aspheric coefficient C2-0, C4=-0, 4461K-05, C6=-0
,1156E-06,C82 0.6830 [Me09
C10 knee 0.4316E-11 26th surface (aspherical surface) Standard paraxial radius of curvature: r = -80,750 Conic coefficient 2k
・1 Aspheric coefficient C2-0, C4:・-0,9459E O5, C6 knee 0.3315E-07, C8= 0.1960E09
C], (To-0,6054E(2fG, ・1), Length n/fr 2=-2,08f0.3 ・113. Family /fT== 7.51-f, 41・ht; u/
b = 12.471 AS - S l / f w =
0.01040...8th surface (r, l):::
□:=・23゜L;+/f! =2.44 fG:a/l fr, = l =4.66QG2R
/ 1st, = a = 0.0641r) / fT = o,
0882 ・・・・・・ FtJr knee 2.9rEn
-rl! P = Q, 1.71 [0 (137N [Example] v tlJv Rev. 11, Iku, 457 2.50 Pox, 0 1-, Hit 0
742 73, (Y?A Xi, Uji.11
゜Maekaruyo 3 -189. μs3. 10 4 44.101 8. Frequency 60゜1-1゜62
0415 106.011 (Tsukasa Ryo DG103
．． 749 1. Group 49.5 1゜77279718
゜συ 6o group 8 -fi, 398:1. , S) 45.
4 1. 4t [36892,417, 10 48.765 9.00 2? , 8
1.699],,,111 -15.829 1
−． 5'l) 43.4 1°84a4212
-6Q, 654 group υ 13 83, field O4, 5064, 11 = 51, gap 014, -73゜^ thirst, pox 15 jurisdiction. 601 11-, (158,91,618,2
316・-29°8=49 2,0■ state. 01” 弼, 074] 7 ・-1 invitation. 715 (variable) 18 60.8! 'd 6゜oa a, 9
1. , 7963119 -91,396. 1
0 2O72,684) 5. (X)58.9 1.5
18 birds 21 -61.74'! 5 3.50η
-35,! 39:11. 2. ■ %, 7 1° rotation 523 1-05.287 (variable) f3
5゜Q%5 59.999f11.01.9998a
5 3.8115 15.897O26,6032 crest 12 19.5 birds 711° nod 6743◎head 2d17
Ka1.0 Eikyaku], S4 Ka34 16. Hino 17Bf
38°1196 47.7881) 56.3529
Paraxial radius of curvature based on the 6th surface (aspherical surface): r=103.
749 yen coefficient 2: 11 induction coefficient C2=O1C4=
011056E-05, C6= 0.1251E-
07, C8 knee 0.8668E (OC10= 0.2
457E-12 Paraxial radius of curvature based on the 22nd surface (aspherical surface): r・-35,691 Conic coefficient: 11 Dielectric surface coefficient C2
-0, C4=-0,4476E, -05, C6=0.1
070E -07, C8=-0,4857E-10Cl
0=0.1316E-12b・,・hhiR/fT”−・
-2,27fI;3・hc:+F/fT=6.64f
GbihGrp/b ””13.62 l AS-3
l/fw = 0.001.97 =-=--6th surface ((i-ri-=27.5) fGl/ f=+ =2
．． 22f(,:!n/l fGz l ””3.2
3QC:! R/hc! R-”'0.0137D/f
−. =0.0882...FN T=2.911
:・n' n・,,==Q, ]41 As can be seen from the values of the specifications of each example, each 1/lens can be made with as few 1/・nes cypress as possible. - configuration 25
Although it is J-1, it can be seen that it has achieved a high magnification zoom lens that is bright with an F number of about 2.8 and has a wide angle of view with a zoom ratio of 2.83. [00381 See FIGS. 2, 3, and 4] Wide-angle end (@ short focal length state) of the zoom lens of Example 1 of the present invention
. Various aberration diagrams are shown in intermediate focal length state 9 and telephoto end (longest focal length state). Figures 6, 7, and 8 are missing.1
The aberration diagram of the zoom lens according to Example 2 of the present invention at the wide-angle end (shortest focal length state) 9Q, the focal length state 9 and the telephoto end (shortest focal length state) 1'' is shown in I-. Figure 11 and Figure 12 respectively show the wide-angle end (@short focal length state), intermediate focal length state, and telephoto end (@long focal length state) of the zoom lens of Example 3 of the present invention.
In the it j, trowel, and steam aberration diagrams showing various aberration diagrams at
435, 8nni), and in each aberration diagram, astigmatism +: The dotted line is the meridional image surface, and the solid line is the spherical image surface (meridional image surface). image plane). In addition, FN in the various aberration diagrams
17 indicates the F number and Y indicates the image height. [0040] Comparison of each aberration diagram shows that in each example, the shiro aberration is very well corrected from the wide-angle end to the telephoto and far ends.
It can be seen that it has excellent imaging performance. Note that focusing in the embodiments of the present invention is performed using an inner focus method in which the second lens group and the third lens group move toward the object at a certain ratio, or a focusing method in which the second lens group and the third lens group move toward the object at a certain ratio. By employing a rear focusing system that moves toward the object, a zoom lens with high performance up to short distances can be realized. Further, it is preferable that the aperture stop is set closer to the image side than the second lens group and closer to the object side than the fourth lens group, and may be moved differently from each group for zooming. [00411 Furthermore, in each of the embodiments according to the present invention, a case was shown in which the negative first lens component G21 in the second lens group O2 was composed of a single lens, but this first lens component G21 was composed of a positive lens and a negative lens. Needless to say, it may be configured by joining with. [00421] [Effects of the Invention] As described above, according to the present invention, each lens group has a compact structure with as few lenses as possible, has a bright F number of about 2.8, and has a zoom ratio of about 3 times. It can be seen that a high-magnification zoom lens with excellent imaging performance from the wide-angle end to the telephoto end has been achieved.

[Brief explanation of the drawing]

FIG. 1 is a lens configuration diagram at a wide-angle end (minimum focal length state), an intermediate focal length state, and a telephoto end (minimum focal length state) in Example 1 of the present invention.

FIG. 2 is a diagram of various aberrations at the wide-angle end (shortest focal length state) in Example 1 of the present invention.

FIG. 3 is a diagram of various aberrations in an intermediate focal length state in Example 1 of the present invention.

FIG. 4 is a diagram of various aberrations at the telephoto end (longest focal length state) in Example 1 of the present invention.

FIG. 5 is a lens configuration diagram at a wide-angle end (minimum focal length state), an intermediate focal length state, and a telephoto end (minimum focal length state) in Example 2 of the present invention.

FIG. 6 is a diagram showing various aberrations at the wide-angle end (shortest focal length state) in Example 2 of the present invention.

FIG. 7 is a diagram of various aberrations in an intermediate focal length state in Example 2 of the present invention.

FIG. 8 is a diagram of various aberrations at the telephoto end (longest focal length state) in Example 2 of the present invention.

FIG. 9 is a lens configuration diagram at a wide-angle end (minimum focal length state), an intermediate focal length state, and a telephoto end (minimum focal length state) in Example 3 of the present invention.

FIG. 10 is a diagram of various aberrations at the wide-angle end (shortest focal length state) in Example 3 of the present invention.

FIG. 11 is a diagram of various aberrations in an intermediate focal length state in Example 3 of the present invention.

FIG. 12 is a diagram of various aberrations at the telephoto end (longest focal length state) in Example 3 of the present invention.

[Explanation of symbols of main parts IGI...41521 group O2
...Second lens group G3...Third lens group G4...
4th lens group [i￥12]

[Figure 4]

[Figure 7) [Figure 9] [Figure 111

Claims (2)

[Claims] Claim 1: In order from the object side, the first lens has a positive refractive power.
a lens group G1 and a second lens group G2 having negative refractive power
, a third lens group G3 having a positive refractive power, and a fourth lens group G4 having a positive refractive power, and the second lens group G2 includes, in order from the object side, a single lens or a cemented lens. A first lens component G21 having a negative refractive power, a second lens component G22 comprising a single lens or a cemented lens and having a negative refractive power, and a third lens component G23 comprising a cemented lens having a positive refractive power. and when changing the magnification from the wide-angle end to the telephoto end, the first lens group G1,
A high-power zoom lens characterized in that the third lens group G3 and the fourth lens group G4 each move toward the object side and satisfy the following conditions. (1) −3≦f_G_2・h_G_2_R/f_T≦−
2 (2) 5≦f_G_3・h_＿G_3_F/f_T≦
9 (3) 10.3≦f_G_4・h_G_4_F/f_
T≦25 However, f_T: Focal length of the entire system at the telephoto end, f_G_2: Focal length of the second lens group G2, f_G_
3: Focal length of the third lens group G3, f_G_4: Focal length of the fourth lens group G4, h_G_2_R: At the telephoto end, the ray from the object point at infinity on the axis is the most image-side surface of the second lens group G2. Height of the ray from the position where it passes through the peripheral edge to the optical axis, h_G_3_F: The height of the ray from the position where the ray from the object point at infinity on the axis passes through the outermost edge of the surface closest to the object of the third lens group G3 at the telephoto end. Height of the ray to the axis, h_G_4_F: Height of the ray from the position where the ray from the object point at infinity on the axis passes through the outermost edge of the surface closest to the object of the fourth lens group G4 to the optical axis at the telephoto end , is. 2. The high-power zoom lens according to claim 1,
A high-power zoom lens characterized in that the second lens group G2 includes an aspherical surface that satisfies the following conditions. (4) 0.
0008≦|AS−S|/fw≦0.05 However, fw:
Focal length of the entire system at the wide-angle end, AS-S: the difference in the optical axis direction between the aspherical surface and a reference spherical surface having a predetermined apex radius of curvature at the outermost periphery of the effective diameter.