Abstract:
A zoom lens with a high zoom ratio has, in the following order from the object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power, and a fourth lens unit having a positive refractive power, and attains zooming from the wide-angle end to the telephoto end by reducing the air gap between the first and second lens units, extending the air gap between the second and third lens units, and reducing the air gap between the third and fourth lens units.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a zoom lens with a high zoom ratio, which is suitable for a single-lens reflex camera, compact camera, video camera, and the like and, more particularly, to a zoom lens with a high zoom ratio, which includes a wide field angle of about 80° or more, and has a zoom ratio of about ×4 or more. 
     2. Related Background Art 
     Conventionally, many zoom lenses each of which includes a wide field angle of about 70° and has a zoom ratio of about ×3 have been proposed. Each of such zoom lenses normally has a negative first lens unit, a positive second lens unit, a negative third lens unit, and a positive fourth lens unit. Since the negative lens unit is arranged at a position closest to the object side, a wide field angle is realized. In addition, the four-unit arrangement assures a high degree of freedom in aberration correction and increases the zoom ratio. As an example of such zoom lenses, Japanese Patent Application Laid-Open No. 62-63909 is known. 
     The field angle, at the wide-angle end, of the zoom lens proposed by Japanese Patent Application Laid-Open No. 62-63909 is about 70°, and the zoom ratio is about ×3. However, in recent years, a zoom lens with a wider field angle and higher zoom ratio is required as a standard zoom lens for a single-lens reflex camera, and the zoom lens proposed by Japanese Patent Application Laid-Open No. 62-63909 cannot satisfy this requirement. 
     In order to satisfy the requirement associated with a wider field angle, Japanese Patent Application Laid-Open No. 5-173071 proposes a zoom lens including a wide field angle of 80° or more. However, the zoom ratio of this zoom lens is as small as ×2 or less, and this lens cannot satisfy the requirement associated with a higher zoom ratio. 
     On the other hand, in order to satisfy the requirement associated with a higher zoom ratio, Japanese Patent Application Laid-Open No. 5-313065 proposes a zoom lens having a zoom ratio exceeding ×4. However, this zoom lens has a field angle, at the wide-angle end, of about 70°, and cannot sufficiently satisfy the requirement associated with a wider field angle. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a compact zoom lens which has a field angle, at the wide-angle end, of 80° or more and a zoom ratio of ×4 or more, and also has good imaging performance. 
     In order to achieve the above object, according to the first aspect of the present invention, a zoom lens of the present invention comprises, in the following order from the object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power, and a fourth lens unit having a positive refractive power, and performs a zooming operation from the wide-angle end to the telephoto end by reducing an air gap between the first and second lens units, extending an air gap between the second and third lens units, and reducing an air gap between the third and fourth lens units. The zoom lens satisfies the following conditions: 
     
         -0.45&lt;f1/fT&lt;-0.15 
    
     
         0.2&lt;f4/fT&lt;0.35 
    
     
         -4.0&lt;B2T&lt;-1.6 
    
     where fT is the focal length of the zoom lens at the telephoto end, f1 is the focal length of the first lens unit, f4 is the focal length of the fourth lens unit, and B2T is the imaging magnification of the second lens unit at the telephoto end. 
     In the zoom lens having the negative first lens unit, the positive second lens unit, the negative third lens unit, and the positive fourth lens unit, at the wide-angle end, a synthesized principal point from the second lens unit to the fourth lens unit is located relatively near the image surface by decreasing the interval between the positive second lens unit and the negative third lens unit, and by increasing the interval between the negative third lens unit and the positive fourth lens unit, and at the telephoto end, the synthesized principal point from the second lens unit to the fourth lens unit is located relatively near the object by increasing the interval between the positive second lens unit and the negative third lens unit, and by decreasing the interval between the negative third lens unit and the positive fourth lens unit. With this arrangement, a large change in distance between the principal point of the negative first lens unit and the synthesized principal point from the second lens unit to the fourth lens unit can be assured, thus increasing the zoom ratio. 
     Furthermore, by changing the intervals between the second and third lens units and between the third and fourth lens units, the curvature of field can be satisfactorily corrected from the wide-angle end to the telephoto end. Even when the zoom ratio is increased, good imaging performance can be obtained. 
     In the above arrangement, the present invention provides conditional formulas (1) to (3) below so as to simultaneously achieve a high zoom ratio and a wide field angle of the zoom lens: 
     
         -0.45&lt;f1/fT&lt;-0.15                                          (1) 
    
     
         0.2&lt;f4/fT&lt;0.35                                             (2) 
    
     
         -4.0&lt;B2T&lt;-1.6                                              (3) 
    
     where 
     fT: the focal length, at the telephoto end, of the zoom lens 
     f1: the focal length of the first lens unit 
     f4: the focal length of the fourth lens unit 
     B2T: the imaging magnification of the second lens unit at the telephoto end 
     Conditional formula (1) defines an optimal range of the focal length of the first lens unit. When f1/fT is smaller than the lower limit of conditional formula (1), the negative refractive power of the first lens unit becomes small, and it is difficult to obtain a high zoom ratio. On the contrary, when f1/fT exceeds the upper limit of conditional formula (1), the negative refractive power of the first lens unit becomes large, and the negative distortion at the wide-angle end generated in the first lens unit becomes excessive. As a result, it becomes difficult to correct distortion especially when a wide field angle is to be realized. 
     Conditional formula (2) defines an optimal range of the focal length of the fourth lens unit. When f4/fT exceeds the upper limit of conditional formula (2), the positive refractive power of the fourth lens unit becomes small, and the back focus at the wide-angle end becomes small. As a result, the fourth lens unit interferes with a mirror in a zoom lens for a single-lens reflex camera. On the other hand, in a compact camera in which the limitations as to the back focus are not strict, the lens diameter of the fourth lens unit increases, thus disturbing a compact structure. On the contrary, when f4/fT is smaller than the lower limit of conditional formula (2), the positive refractive power of the fourth lens unit becomes excessive, and the arrangement of the fourth lens unit becomes complicated to achieve aberration correction. For this reason, the total length of the zoom lens increases, thus disturbing a compact structure. 
     Conditional formula (3) defines an optimal range of the imaging magnification of the second lens unit at the telephoto end. When B2T is smaller than the lower limit of conditional formula (3), the absolute value of the imaging magnification of the second lens unit becomes large, and various aberrations generated in the first lens unit are magnified. As a result, since the aberrations generated in the first lens group must be suppressed to be very small, the arrangement of the first lens unit is complicated and becomes large. For this reason, such small B2T is not preferable. On the contrary, when B2T exceeds the upper limit of conditional formula (3), the total length (the distance from a lens surface closest to the object side to a lens surface closest to the image side) of the zoom lens at the wide-angle end and the effective diameter of the first lens unit increase, thus disturbing a compact structure. 
     The present invention also provides conditional formulas (4) to (6) below as more preferable conditions: 
     
         -0.30&lt;f3/fT&lt;-0.15                                          (4) 
    
     
         2.8&lt;B2T/B2W&lt;6.0                                            (5) 
    
     
         -3.0&lt;Δe2/Δe3&lt;-0.9                              (6) 
    
     where 
     f3: the focal length of the third lens unit 
     B2W: the imaging magnification of the second lens unit at the wide-angle end 
     Δe2: the difference between intervals between the second and third lens units at the telephoto end and the wide-angle end of the zoom lens 
     Δe3: the difference between intervals between the third and fourth lens units at the telephoto end and the wide-angle end of the zoom lens 
     Conditional formula (4) defines a proper range of the focal length of the third lens unit. When f3/fT is smaller than the lower limit of conditional formula (4), the negative refractive power of the third lens unit becomes small, and a change in synthesized principal point position from the second lens unit to the fourth lens unit upon zooming becomes small. As a result, it is difficult to achieve a high zoom ratio. On the contrary, when f3/fT exceeds the upper limit of conditional formula (4), the negative refractive power of the third lens unit becomes large, and the total length of the zoom lens increases, thus disturbing a compact structure. 
     Conditional formula (5) defines an appropriate range of the ratio between the imaging magnifications of the second lens unit at the telephoto end and the wide-angle end. When the ratio exceeds the upper limit of conditional formula (5), a change in imaging magnification of the second lens unit becomes large, and changes in various aberrations upon zooming, in particular, changes in spherical aberration and coma, become large. As a result, it is difficult to correct these aberrations. On the contrary, when the ratio is smaller than the lower limit of conditional formula (5), a change in imaging magnification of the second lens unit becomes small, and it becomes difficult to achieve a high zoom ratio. 
     Conditional formula (6) defines an appropriate range of the ratio between a change in interval between the second and third lens units upon zooming and a change in interval between the third and fourth lens units upon zooming. When the ratio is smaller than the lower limit of conditional formula (6), the change in interval between the third and fourth lens units becomes relatively small, and it becomes difficult to correct a variation in curvature of field upon zooming. Therefore, such a small ratio is not preferable. When the ratio exceeds the upper limit of conditional formula (6), the change in interval between the second and third lens units becomes relatively small, and the effective diameter of the third lens unit at the telephoto end and the aperture size increase. For this reason, such a large ratio is not preferable, either. In order to decrease the aperture size, the upper limit value of conditional formula (6) is more preferably set to be -1.2. 
     Furthermore, in order to achieve both a compact zoom lens and satisfactory aberration correction, an aspherical surface is preferably arranged in the first lens unit. In this case, the aspherical surface preferably has an aspherical surface shape, so that the negative refractive power gradually decreases toward the peripheral portion. 
     Furthermore, in order to correct spherical aberration and distortion, which tend to be generated in the fourth lens unit, with good balance, an aspherical surface is preferably arranged in the fourth lens unit. In this case, the aspherical surface is preferably arranged on a boundary surface with the air, and preferably has an aspherical surface shape, so that the positive refractive power gradually decreases toward the peripheral portion. 
     According to the second aspect of the present invention, a zoom lens comprises, in the following order from the object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power, and a fourth lens unit having a positive refractive power, and performs a zooming operation from the wide-angle end to the telephoto end by reducing an air gap between the first and second lens units, extending an air gap between the second and third lens units, and reducing an air gap between the third and fourth lens units. The zoom lens satisfies the following conditions: 
     
         -0.45&lt;f1/fT&lt;-0.20 
    
     
         -3.0&lt;f3/fW&lt;-1.2 
    
     
         2.0&lt;f4/fW&lt;6.0 
    
     where fW is the focal length of the zoom lens at the wide-angle end, fT is the focal length of the zoom lens at the telephoto end, f1 is the focal length of the first lens unit, f3 is the focal length of the third lens unit, and f4 is the focal length of the fourth lens unit. 
     In the zoom lens having the negative first lens unit, the positive second lens unit, the negative third lens unit, and the positive fourth lens unit as in the present invention, at the wide-angle end, a synthesized principal point from the second lens unit to the fourth lens unit is located relatively near the image surface by decreasing the interval between the positive second lens unit and the negative third lens unit, and by increasing the interval between the negative third lens unit and the positive fourth lens unit, and at the telephoto end, the synthesized principal point from the second lens unit to the fourth lens unit is located relatively near the object by increasing the interval between the positive second lens unit and the negative third lens unit, and by decreasing the interval between the negative third lens unit and the positive fourth lens unit. With this arrangement, a large change in distance between the principal point of the negative first lens unit and the synthesized principal point from the second lens unit to the fourth lens unit can be assured, thus increasing the zoom ratio. Furthermore, by changing the intervals between the second and third lens units and between the third and fourth lens units, the curvature of field can be satisfactorily corrected from the wide-angle end to the telephoto end. Even when the zoom ratio is increased, good imaging performance can be obtained. 
     In the above arrangement, the present invention provides conditional formulas (7) to (9) below so as to simultaneously achieve a high zoom ratio and a wide field angle of the zoom lens: 
     
         -0.45&lt;f1/fT&lt;-0.20                                          (7) 
    
     
         -3.0&lt;f3/fW&lt;-1.2                                            (8) 
    
     
         2.0&lt;f4/fW&lt;6.0                                              (9) 
    
     where 
     fW: the focal length, at the wide-angle end, of the zoom lens 
     fT: the focal length, at the telephoto end, of the zoom lens 
     f1: the focal length of the first lens unit 
     f3: the focal length of the third lens unit 
     f4: the focal length of the fourth lens unit 
     Conditional formula (7) defines an optimal range of the focal length of the first lens unit. When f1/fT is smaller than the lower limit of conditional formula (7), the negative refractive power of the first lens unit becomes small, and it is difficult to obtain a high zoom ratio. On the contrary, when f1/fT exceeds the upper limit of conditional formula (7), the negative refractive power of the first lens unit becomes large, and the negative distortion at the wide-angle end generated in the first lens unit becomes excessive. As a result, it becomes difficult to correct distortion especially when a wide field angle is to be achieved. 
     Conditional formula (8) defines an optimal range of the focal length of the third lens unit. When f3/fW is smaller than the lower limit of conditional formula (8), the negative refractive power of the third lens unit becomes small, and a change in synthesized principal point position from the second lens unit to the fourth lens unit upon zooming becomes small. As a result, it becomes difficult to achieve a high zoom ratio. On the contrary, when f3/fW exceeds the upper limit of conditional formula (8), the negative refractive power of the third lens unit becomes large, and the total length (the distance from a lens surface closest to the object side to an image surface) of the zoom lens increases, thus disturbing a compact structure. 
     Conditional formula (9) defines an optimal range of the focal length of the fourth lens unit. When f4/fW exceeds the upper limit of conditional formula (9), the positive refractive power of the fourth lens unit becomes small, and the back focus at the wide-angle end decreases. As a result, the fourth lens unit interferes with a mirror in a zoom lens for a single-lens reflex camera. On the other hand, in a compact camera in which the limitations as to the back focus are not strict, the lens diameter of the fourth lens unit increases, thus disturbing a compact structure. On the contrary, when f4/fW is smaller than the lower limit of conditional formula (9), the positive refractive power of the fourth lens unit becomes excessive, and the arrangement of the fourth lens unit must be complicated to achieve aberration correction. For this reason, the total length of the zoom lens increases, thus disturbing a compact structure. 
     The present invention provides conditional formulas (10) to (14) below as more preferable conditions: 
     
         0.7&lt;f3/f1&lt;2.0                                              (10) 
    
     
         2.8&lt;B2T/B2W&lt;5.0                                            (11) 
    
     
         0.5&lt;f1-3W/fW&lt;5                                             (12) 
    
     
         1&lt;f1-3T/f1                                                 (13) 
    
     
         0.03&lt;T4/fT&lt;0.10                                            (14) 
    
     where 
     B2W: the imaging magnification of the second lens unit at the wide-angle end 
     B2T: the imaging magnification of the second lens unit at the telephoto end 
     f1-3W: the synthesized focal length of the first, second, and third lens units at the wide-angle end 
     f1-3T: the synthesized focal length of the first, second, and third lens units at the telephoto end 
     T4: the on-axis thickness from a lens surface closest to the object side to a lens surface closest to the image side in the fourth lens unit 
     Conditional formula (10) defines an appropriate range of the ratio between the focal lengths of the third and first lens units. When the ratio exceeds the upper limit of conditional formula (10), the refractive power of the first lens unit becomes relatively large, and it becomes difficult to correct various aberrations such as distortion at the wide-angle end. On the contrary, when the ratio is smaller than the lower limit of conditional formula (10), the refractive power of the first lens unit becomes relatively small, and it becomes difficult to achieve a high zoom ratio. 
     Conditional formula (11) defines an appropriate range of the ratio between the imaging magnifications of the second lens unit at the telephoto end and the wide-angle end. When the ratio exceeds the upper limit of conditional formula (11), a change in imaging magnification of the second lens unit becomes large, and changes in various aberrations, especially, changes in spherical aberration and coma, become large. As a result, it becomes difficult to correct such aberrations. On the contrary, when the ratio is smaller than the lower limit of conditional formula (11), a change in imaging magnification of the second lens unit becomes small, and it becomes difficult to achieve a high zoom ratio. 
     In the present invention, on-axis light rays which pass between the third and fourth lens units are weakly convergent rays at the wide-angle end, and are weakly divergent rays at the telephoto end. This arrangement is preferable to decrease the total length of the zoom lens and to assure a sufficient back focus at the wide-angle end at the same time. Conditional formulas (12) and (13) are preferred conditions for such an arrangement. 
     Conditional formula (12) defines an appropriate range of the synthesized focal length from the first lens unit to the third lens unit at the wide-angle end. When f1-3W/fW is smaller than the lower limit of conditional formula (12), on-axis light rays which pass between the third and fourth lens units become strongly convergent rays at the wide-angle end, and it becomes difficult to assure a sufficient back focus. On the contrary, when f1-3W/fW exceeds the upper limit of conditional formula (12), on-axis light rays which pass between the third and fourth lens units become substantially collimated rays at the wide-angle end. As a result, the total length of the zoom lens increases, thus disturbing a compact structure. 
     Conditional formula (13) defines an appropriate range of the synthesized focal length from the first lens unit to the third lens unit at the telephoto end. When f1-3T/f1 is smaller than the lower limit of conditional formula (13), on-axis light rays which pass between the third and fourth lens units become strongly divergent rays at the telephoto end, and the total length of the zoom lens increases, thus disturbing a compact structure. 
     Conditional formula (14) defines an appropriate range of the thickness of the fourth lens unit. When T4/fT is smaller than the lower limit of conditional formula (14), a sufficient central thickness of each of lenses constituting the fourth lens unit, and a sufficient thickness (edge thickness) of the outer peripheral portion of the lens cannot be assured. On the contrary, when T4/fT exceeds the upper limit of the conditional formula (14), the total thickness of the fourth lens unit increases, and such large T4/fT is not preferable since it results in an increase in size of the zoom lens and an insufficient back focus. In order to satisfactorily correct spherical aberration and chromatic aberration under conditional formula (14), the fourth lens unit is preferably constituted by a single negative lens and a single positive lens. In this case, in order to facilitate assembling/adjustment, the negative and positive lenses are preferably cemented to each other. Furthermore, the fourth lens unit preferably satisfies conditional formulas (15) and (16) below: 
     
         nN-nP&gt;0                                                    (15) 
    
     
         νP-νN&gt;10                                             (16) 
    
     where 
     nN: the refractive index of the negative lens constituting the fourth lens unit 
     nP: the refractive index of the positive lens constituting the fourth lens unit 
     νN: the Abbe&#39;s number of the negative lens constituting the fourth lens unit 
     νP: the Abbe&#39;s number of the positive lens constituting the fourth lens unit 
     Conditional formula (15) defines an appropriate range of the difference between the refractive indices of the negative and positive lenses constituting the fourth lens unit. When the difference is smaller than the lower limit of conditional formula (15), the spherical aberration generated in the fourth lens unit increases. For this reason, such a small difference is not preferable. 
     Conditional formula (16) defines an appropriate range of the difference between the Abbe&#39;s numbers of the negative and positive lenses constituting the fourth lens unit. When the difference is smaller than the lower limit of conditional formula (16), the chromatic aberration generated in the fourth lens unit increases. For this reason, such a small difference is not preferable. 
     Furthermore, in order to correct spherical aberration and distortion, which tend to be generated in the fourth lens unit, with a good balance, an aspherical surface is preferably arranged in the fourth lens unit. In this case, the aspherical surface is preferably arranged at a boundary surface with the air, and preferably has an aspherical surface shape, so that the positive refractive power gradually decreases toward the peripheral portion. 
     Note that an aspherical surface amount A(h) is defined by the following formula: 
     
         A(h)=X(h)-(h.sup.2 /r)/[1+(1-h.sup.2 /r.sup.2).sup. 1/2 ] 
    
     where h is the height from the optical axis, X(h) is the distance from the tangent plane of the vertex of the aspherical surface to the aspherical surface at the height h along the optical axis direction, and r is the paraxial radius of curvature of the aspherical surface. 
     In this case, the aspherical surface shape in the fourth lens unit preferably satisfies conditional formulas (17) and (18) below: 
     
         (nF-nR)·A(Y/3)&gt;0                                  (17) 
    
     
         A(Y/3)/A(Y/4)&gt;2                                            (18) 
    
     where Y is the maximum image height, nF is the refractive index, on the object side, of the aspherical surface, and nR is the refractive index, on the image side, of the aspherical surface. 
     When the aspherical surface shape falls outside the ranges of conditional formulas (17) and (18), it becomes difficult to correct spherical aberration and distortion with a good balance. 
     Furthermore, in order to achieve both a compact zoom lens and satisfactory aberration correction, an aspherical surface is preferably arranged in the first lens unit. In this case, the aspherical surface preferably has an aspherical surface shape, so that the negative refractive power gradually decreases toward the peripheral portion. 
     The above and other objects, features and advantages of the present invention are explained hereinafter and may be better understood by reference to the drawings and the descriptive matter which follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view showing the lens arrangement according to a first embodiment of the present invention; 
     FIG. 2 is a view showing the lens arrangement according to a second embodiment of the present invention; 
     FIG. 3 is a view showing the lens arrangement according to a third embodiment of the present invention; 
     FIG. 4 is a view showing the lens arrangement according to a fourth embodiment of the present invention; 
     FIG. 5 is a view showing the lens arrangement according to a fifth embodiment of the present invention; 
     FIG. 6 is a view showing the lens arrangement according to a sixth embodiment of the present invention; 
     FIG. 7 is a view showing the lens arrangement according to a seventh embodiment of the present invention; 
     FIG. 8 is a view showing the lens arrangement according to a eighth embodiment of the present invention; 
     FIG. 9 is a view showing the lens arrangement according to a ninth embodiment of the present invention; 
     FIG. 10 shows graphs of various aberrations at the wide-angle end according to the first embodiment of the present invention; 
     FIG. 11 shows graphs of various aberrations in an intermediate focal length state according to the first embodiment of the present invention; 
     FIG. 12 shows graphs of various aberrations at the telephoto end according to the first embodiment of the present invention; 
     FIG. 13 shows graphs of various aberrations at the wide-angle end according to the second embodiment of the present invention; 
     FIG. 14 shows graphs of various aberrations in an intermediate focal length state according to the second embodiment of the present invention; 
     FIG. 15 shows graphs of various aberrations at the telephoto end according to the second embodiment of the present invention; 
     FIG. 16 shows graphs of various aberrations at the wide-angle end according to the third embodiment of the present invention; 
     FIG. 17 shows graphs of various aberrations in an intermediate focal length state according to the third embodiment of the present invention; 
     FIG. 18 shows graphs of various aberrations at the telephoto end according to the third embodiment of the present invention; 
     FIG. 19 shows graphs of various aberrations at the wide-angle end according to the fourth embodiment of the present invention; 
     FIG. 20 shows graphs of various aberrations in an intermediate focal length state according to the fourth embodiment of the present invention; 
     FIG. 21 shows graphs of various aberrations at the telephoto end according to the fourth embodiment of the present invention; 
     FIG. 22 shows graphs of various aberrations at the wide-angle end according to the fifth embodiment of the present invention; 
     FIG. 23 shows graphs of various aberrations in an intermediate focal length state according to the fifth embodiment of the present invention; 
     FIG. 24 shows graphs of various aberrations at the telephoto end according to the fifth embodiment of the present invention; 
     FIG. 25 shows graphs of various aberrations at the wide-angle end according to the sixth embodiment of the present invention; 
     FIG. 26 shows graphs of various aberrations in an intermediate focal length state according to the sixth embodiment of the present invention; 
     FIG. 27 shows graphs of various aberrations at the telephoto end according to the sixth embodiment of the present invention; 
     FIG. 28 shows graphs of various aberrations at the wide-angle end according to the seventh embodiment of the present invention; 
     FIG. 29 shows graphs of various aberrations in an intermediate focal length state according to the seventh embodiment of the present invention; 
     FIG. 30 shows graphs of various aberrations at the telephoto end according to the seventh embodiment of the present invention; 
     FIG. 31 shows graphs of various aberrations at the wide-angle end according to the eighth embodiment of the present invention; 
     FIG. 32 shows graphs of various aberrations in an intermediate focal length state according to the eighth embodiment of the present invention; 
     FIG. 33 shows graphs of various aberrations at the telephoto end according to the eighth embodiment of the present invention; 
     FIG. 34 shows graphs of various aberrations at the wide-angle end according to the ninth embodiment of the present invention; 
     FIG. 35 shows graphs of various aberrations in an intermediate focal length state according to the ninth embodiment of the present invention; and 
     FIG. 36 shows graphs of various aberrations at the telephoto end according to the ninth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 to 9 respectively show the lens arrangements according to the first to ninth embodiments of the present invention. 
     In data tables of the respective embodiments, f is the focal length, F is the f-number, and 2ω is the field angle. Furthermore, numerals in the leftmost column represent the order of lens surfaces from the object side, r is the radius of curvature of each lens surface, d is the lens surface interval, and n and ν are respectively the refractive index and Abbe&#39;s number for the d-line (λ=587.6 nm). In addition, a surface with a mark * attached to the corresponding numeral in the leftmost column is an aspherical surface. The aspherical surface shape is expressed by: 
     
         X(h)=(h.sup.2 /r)/[1+(1-kh.sup.2 /r.sup.2).sup. 1/2 ]+C4h.sup.4 +C6h.sup.6 +C8h.sup.8 +C10h.sup.10 
    
     where h is the height from the optical axis in a direction perpendicular to the optical axis, X(h) is the distance from the tangent plane of the vertex of the aspherical surface to the aspherical surface at the height h along the optical axis direction, r is the paraxial radius of curvature, k is a coefficient of cone, and Cn is an n-th order aspherical surface coefficient. Note that the maximum image height is Y=21.6 in each embodiment. 
     [First Embodiment] 
     In the first embodiment, as shown in FIG. 1, a negative first lens unit G1 includes, in the following order from the object side, a biconcave negative lens having an aspherical surface on its image side, and a cemented lens of a biconvex positive lens and a biconcave negative lens. A positive second lens unit G2 includes, in the following order from the object side, a cemented lens of a negative meniscus lens having a convex surface facing the object side and a biconvex positive lens, a cemented lens of a biconvex positive lens and a biconcave negative lens, and a biconvex positive lens. A negative third lens unit G3 includes, in the following order from the object side, a cemented lens of a positive meniscus lens having a concave surface facing the object side and a biconcave negative lens, and a negative meniscus lens having a concave surface facing the object side. A positive fourth lens unit G4 includes, in the following order from the object side, a biconvex positive lens having an aspherical surface on its image side, and a cemented lens of a biconvex positive lens and a biconcave negative lens. A stop S is located between the second and third lens units G2 and G3, and moves integrally with the third lens unit G3 upon zooming. 
     
                       TABLE 1______________________________________Data Values of First Embodimentf = 24.70 to 117.00F = 3.63 to 5.742ω = 85.8 to 20.6°   r         d           ν n______________________________________ 1      -131.6912 2.0000      57.31                              1.67000 2*     28.0231   1.5000 3      41.1438   7.9000      25.36                              1.80518 4      -760.3533 2.0000      54.66                              1.72916 5      35.4254   D5 6      40.5115   1.3000      23.83                              1.84666 7      25.2255   6.5000      70.24                              1.48749 8      -65.2860  0.1000 9      32.9756   7.0000      70.24                              1.4874910      -45.4583  1.3000      33.27                              1.8061011      325.9241  0.100012      40.0380   5.0000      43.92                              1.6056213      -511.1512 D1314      (stop)    1.500015      -117.9745 3.0000      23.83                              1.8466616      -24.5271  1.1000      64.20                              1.5168017      37.5250   2.500018      -26.7507  1.1000      43.04                              1.8475019      -289.2668 D1920      90.2400   5.5000      58.44                              1.65160 21*    -30.4940  0.100022      54.2164   6.0000      70.45                              1.4874923      -51.8277  1.2000      25.46                              1.8051824      341.9931  BfSecond Surface Aspherical Surface Coefficientsk = 1.000          C4 = -0.1019 × 10.sup.-4C6 = -0.7017 × 10.sup.-8              C8 = 0.7760 × 10.sup.-11C10 = -0.1534 × 10.sup.-1321st Surface Aspherical Surface Coefficientsk = 1.000          C4 = 0.8640 × 10.sup.-5C6 = 0.2559 × 10.sup.-7              C8 = -0.5444 × 10.sup.-10C10 = -0.6038 × 10.sup.-13Change in Interval Upon Zoomingf        24.6998       48.9998 117.0017D5       32.4458       11.2472 1.0000D13      1.0000        9.7032  25.3695D19      13.8542       7.4402  1.0000Bf       38.1001       53.7971 96.0334Condition Corresponding Values    (1) f1/fT = -0.275    (2) f4/fT = 0.286    (3) B2T = -2.535    (4) f3/fT = -0.232    (5) B2T/B2W = 3.658    (6) Δe2/Δe3 = -1.896______________________________________ 
    
     [Second Embodiment] 
     In the second embodiment, as shown in FIG. 2, a negative first lens unit G1 includes, in the following order from the object side, a negative meniscus lens having a convex surface facing the object side, a negative lens having an aspherical surface on its object side and a concave surface facing the image side, and a positive meniscus lens having a convex surface facing the object side. A positive second lens unit G2 includes, in the following order from the object side, a positive lens having a convex surface facing the object side, a biconvex positive lens, and a cemented lens of a biconvex positive lens and a biconcave negative lens. A negative third lens unit G3 includes, in the following order from the object side, a cemented lens of a positive meniscus lens having a concave surface facing the object side and a biconcave negative lens, and a biconcave negative lens. A positive fourth lens unit G4 includes, in the following order from the object side, a cemented lens of a negative lens having an aspherical surface on its object side and a biconvex positive lens. A stop S is located between the second and third lens units G2 and G3, and moves integrally with the third lens unit G3 upon zooming. 
     The data values and the condition corresponding values of the second embodiment will be summarized below. 
     
                       TABLE 2______________________________________Data Values of Second Embodimentf = 24.73 to 101.91F = 3.61 to 5.742ω = 85.0 to 23.9°   r          d          ν n______________________________________ 1      134.0814   2.0000     46.53                              1.80411 2      26.8030    9.6000 3*     -408.8541  2.0000     70.45                              1.48749 4      45.0510    0.4000 5      37.6455    4.4000     23.01                              1.86074 6      70.4556    D6 7      79.5627    2.4000     70.45                              1.48749 8      -15685.1950              0.1000 9      72.0590    3.9000     70.45                              1.4874910      -72.0590   0.100011      26.6245    5.7000     70.45                              1.4874912      -68.6946   1.1000     23.01                              1.8607413      648.6916   D1314      (stop)     1.500015      -133.8865  2.9000     23.01                              1.8607416      -29.4116   1.0000     40.75                              1.5814417      70.3940    1.300018      -100.1752  1.1000     39.61                              1.8045419      100.1754   D19 20*    137.3857   1.2000     23.01                              1.8607421      55.6664    4.0000     57.03                              1.6228022      -55.6663   BfThird Surface Aspherical Surface Coefficientsk = 1.000          C4 = 0.2523 × 10.sup.-5C6 = 0.3865 × 10.sup.-8              C8 = -0.7973 × 10.sup.-11C10 = 0.1805 × 10.sup.-1320th Surface Aspherical Surface Coefficientsk = 1.000          C4 = -0.9256 × 10.sup.-5C6 = -0.5305 × 10.sup.-8              C8 = -0.1131 × 10.sup.-9C10 = 0.3622 × 10.sup.-12Change in Interval Upon Zoomingf        24.7270       49.0112 101.9078D6       56.6702       18.6000 2.0000D13      2.5000        7.4960  8.6983D19      16.2000       7.9000  2.0000Bf       38.0015       57.3333 107.5903Condition Corresponding Values  (7)  f1/fT = -0.383  (8)  f3/fW = -1.878  (9)  f4/fW = 3.088  (10) f3/f1 = 1.189  (11) B2T/B2W = 3.398  (12) f1 - 3W/fW = 2.028  (13) f1 - 3T/f1 = 6.240  (14) T4/fT = 0.051  (15) nN - nP = 0.23794  (16) νP - νN = 34.02  (17) (nF - nR) · A(Y/3) = 0.0226  (18) A(Y/3)/A(Y/4) = 3.254______________________________________ 
    
     [Third Embodiment] 
     In the third embodiment, as shown in FIG. 3, a negative first lens unit G1 includes, in the following order from the object side, a negative meniscus lens having a convex surface facing the object side, a biconcave negative lens having an aspherical surface on its object side, and a positive meniscus lens having a convex surface facing the object side. A positive second lens unit G2 includes, in the following order from the object side, a biconvex positive lens having an aspherical surface on its object side, and a cemented lens of a biconvex positive lens and a negative meniscus lens having a concave surface facing the object side. A negative third lens unit G3 includes, in the following order from the object side, a cemented lens of a positive meniscus lens having a concave surface facing the object side and a biconcave negative lens, and a biconcave negative lens. A positive fourth lens unit G4 includes, in the following order from the object side, a cemented lens of a negative lens having an aspherical surface on its object side and a biconvex positive lens. A stop S is located between the second and third lens units G2 and G3, and moves integrally with the third lens unit G3 upon zooming. 
     The data values and the condition corresponding values of the third embodiment will be summarized below. 
     
                       TABLE 3______________________________________Data Values of Third Embodimentf = 24.70 to 101.90F = 3.59 to 5.762ω = 85.1 to 23.9°   r         d           ν n______________________________________ 1      104.2235  2.0000      46.53                              1.80411 2      25.8606   10.1000 3*     -216.8961 2.0000      70.45                              1.48749 4      48.2166   0.1500 5      37.4402   4.3000      23.01                              1.86074 6      71.0656   D6 7*     35.1890   5.2000      70.45                              1.48749 8      -59.4696  0.1000 9      35.2772   5.5000      70.45                              1.4874910      -42.1373  1.1000      23.01                              1.8607411      -158.5682 D1112      (stop)    1.500013      -147.4506 2.8000      23.01                              1.8607414      -32.0581  1.0000      45.87                              1.5481415      49.9889   1.400016      -104.5431 1.1000      46.53                              1.8041117      104.5446  D17 18*    844.4847  1.2000      23.01                              1.8607419      54.0396   4.3000      46.79                              1.7668420      -54.0396  BfThird Surface Aspherical Surface Coefficientsk = 1.000          C4 = 0.2119 × 10.sup.-5C6 = 0.3738 × 10.sup.-8              C8 = -0.8468 × 10.sup.-11C10 = 0.1897 × 10.sup.-13Seventh Surface Aspherical Surface Coefficientsk = 1.000          C4 = -0.3464 × 10.sup.-5C6 = -0.2286 × 10.sup.-8              C8 = 0.6150 × 10.sup.-11C10 = -0.3735 × 10.sup.-1418th Surface Aspherical Surface Coefficientsk = 1.000          C4 = -0.7748 × 10.sup.-5C6 = -0.1290 × 10.sup.-8              C8 = -0.1497 × 10.sup.-9C10 = 0.4915 × 10.sup.-12Change in Interval Upon Zoomingf        24.7000       49.0001 101.9008D6       58.6530       19.0236 2.0000D11      2.5000        7.1476  7.8945D17      17.0970       8.6575  2.0000Bf       38.0934       57.4602 108.0300Condition Corresponding Values  (7)  f1/fT = -0.391  (8)  f3/fW = -1.781  (9)  f4/fW = 3.002  (10) f3/f1 = 1.104  (11) B2T/B2W = 3.392  (12) f1 - 3W/fW = 2.052  (13) f1 - 3T/f1 = 5.608  (14) T4/fT = 0.054  (15) nN - nP = 0.09390  (16) νP - νN = 23.78  (17) (nF - nR) · A(Y/3) = 0.0189  (18) A(Y/3)/A(Y/4) = 3.259______________________________________ 
    
     [Fourth Embodiment] 
     In the fourth embodiment, as shown in FIG. 4, a negative first lens unit G1 includes, in the following order from the object side, a negative meniscus lens having a convex surface facing the object side, a negative meniscus lens having an aspherical surface on its object side and a concave surface facing the image side, and a positive meniscus lens having a convex surface facing the object side. A positive second lens unit G2 includes, in the following order from the object side, a cemented lens of a negative meniscus lens having a convex surface facing the object side and a biconvex positive lens, a positive lens having a convex surface facing the object side, and a positive meniscus lens having a convex surface facing the object side. A negative third lens unit G3 includes, in the following order from the object side, a cemented lens of a positive meniscus lens having a concave surface facing the object side and a biconcave negative lens, and a biconcave negative lens. A positive fourth lens unit G4 includes, in the following order from the object side, a cemented lens of a negative lens having an aspherical surface on its object side and a biconvex positive lens. A stop S is located between the second and third lens units G2 and G3, and moves integrally with the third lens unit G3 upon zooming. 
     The data values and the condition corresponding values of the fourth embodiment will be summarized below. 
     
                       TABLE 4______________________________________Data Values of Fourth Embodimentf = 24.70 to 101.89F = 3.60 to 5.752ω = 85.2 to 23.7°   r          d          ν n______________________________________ 1      193.5896   2.0000     46.54                              1.81584 2      27.2849    7.9573 3*     155.4207   2.0000     70.45                              1.48749 4      32.5605    0.2038 5      30.8988    5.6593     23.83                              1.84666 6      54.0189    D6 7      34.5395    1.1000     23.83                              1.84666 8      22.5757    5.3891     70.45                              1.48749 9      -266.6545  0.100010      35.1228    3.7705     70.45                              1.4874911      -22979.9760              0.100012      40.6230    3.1585     70.45                              1.4874913      333.5510   D1314      (stop)     1.500015      -67.0372   2.5198     23.83                              1.8466616      -26.3749   1.0000     52.16                              1.5174217      115.6416   0.741118      -126.6914  1.1000     46.54                              1.8158419      72.5170    D19 20*    806.8021   1.2000     23.83                              1.84666 21*    41.8981    4.2707     46.54                              1.8158422      -75.7538   BfThird Surface Aspherical Surface Coefficientsk = 1.000          C4 = 0.3093 × 10.sup.-5C6 = 0.5745 × 10.sup.-8              C8 = -0.9632 × 10.sup.-11C10 = 0.1871 × 10.sup.-1320th Surface Aspherical Surface Coefficientsk = 1.000          C4 = -0.1008 × 10.sup.-4C6 = -0.1253 × 10.sup.-7              C8 = -0.1030 × 10.sup.-9C10 = 0.3724 × 10.sup.-12Change in Interval Upon Zoomingf        24.7046       49.0058 101.8905D6       58.2502       19.3312 2.0000D13      2.7899        8.1882  12.0878D19      17.1900       9.5718  2.0000Bf       37.9972       55.1959 98.7309Condition Corresponding Values  (7)  f1/fT = -0.378  (8)  f3/fW = -1.791  (9)  f4/fW = 3.658  (10) f3/f1 = 1.149  (11) B2T/B2W = 3.326  (12) f1 - 3W/fW = 1.730  (13) f1 - 3T/f1 = 28.09  (14) T4/fT = 0.054  (15) nN - nP = 0.03082  (16) νP - νN = 22.71  (17) (nF - nR) · A(Y/3) = 0.0249  (18) A(Y/3)/A(Y/4) = 3.289______________________________________ 
    
     [Fifth Embodiment] 
     In the fifth embodiment, as shown in FIG. 5, a negative first lens unit G1 includes, in the following order from the object side, a negative lens having an aspherical surface on its object side and a concave surface facing the image side, and a cemented lens of a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side. A positive second lens unit G2 includes, in the following order from the object side, a cemented lens of a negative meniscus lens having a convex surface facing the object side and a biconvex positive lens, a positive meniscus lens having a convex surface facing the object side, and a positive meniscus lens having a convex surface facing the object side. A negative third lens unit G3 includes, in the following order from the object side, a cemented lens of a positive meniscus lens having a concave surface facing the object side and a biconcave negative lens, and a biconcave negative lens. A positive fourth lens unit G4 includes, in the following order from the object side, a cemented lens of a negative lens having an aspherical surface on its object side and a biconvex positive lens. A stop S is located between the second and third lens units G2 and G3, and moves integrally with the third lens unit G3 upon zooming. 
     The data values and the condition corresponding values of the fifth embodiment will be summarized below. 
     
                       TABLE 5______________________________________Data Values of Fifth Embodimentf = 24.70 to 101.86F = 3.67 to 5.992ω = 85.3 to 23.8°   r         d           ν n______________________________________ 1*     -1605.4200             2.0000      42.97                              1.83500 2      32.9109   6.7004 3      143.9710  2.0000      70.45                              1.48749 4      29.5201   5.9264      23.83                              1.84666 5      53.8745   D5 6      45.1454   1.1000      23.83                              1.84666 7      25.5773   4.5801      70.45                              1.48749 8      -123.6291 0.1000 9      30.0545   3.7065      64.20                              1.5168010      328.0298  0.100011      34.6513   2.9698      59.44                              1.5831312      120.4928  D1213      (stop)    1.500014      -334.0987 2.9046      33.27                              1.8061015      -28.2351  1.0000      64.20                              1.5168016      43.1811   1.619117      -54.6920  1.1000      46.54                              1.8158418      136.8433  D18 19*    96.9585   1.2000      23.83                              1.8466620      45.1047   5.3598      70.45                              1.48749 21*    -39.2857  BfFirst Surface Aspherical Surface Coefficientsk = 1.000          C4 = 0.2175 × 10.sup.-5C6 = -0.6822 × 10.sup.-9              C8 = -0.2754 × 10.sup.-12C10 = 0.4061 × 10.sup.-1519th Surface Aspherical Surface Coefficientsk = 1.000          C4 = -0.1234 × 10.sup.-4C6 = -0.2421 × 10.sup.-7              C8 = 0.6472 × 10.sup.-10C10 = -0.3629 × 10.sup.-11Change in Interval Upon Zoomingf        24.6964       48.9891 101.8551D5       52.2024       16.9518 1.0000D12      1.0000        5.1699  9.0763D18      14.9309       7.5126  1.0000Bf       38.0891       56.5842 97.5573Condition Corresponding Values  (7)  f1/fT = -0.370  (8)  f3/fW = -1.611  (9)  f4/fW = 3.087  (10) f3/f1 = 1.057  (11) B2T/B2W = 3.281  (12) f1 - 3W/fW = 2.033  (13) f1 - 3T/f1 = 9.389  (14) T4/fT = 0.064  (15) nN = nP = 0.35917  (16) νP - νN = 46.62  (17) (nF - nR) · A(Y/3) = 0.0306  (18) A(Y/3)/A(Y/4) = 3.276______________________________________ 
    
     [Sixth Embodiment] 
     In the sixth embodiment, as shown in FIG. 6, a negative first lens unit G1 includes, in the following order from the object side, a negative meniscus lens having a convex surface facing the object side, and a cemented lens of a negative meniscus lens having an aspherical surface on its object side and a concave surface facing the image side and a positive meniscus lens having a convex surface facing the object side. A positive second lens unit G2 includes, in the following order from the object side, a cemented lens of a negative meniscus lens having a convex surface facing the object side and a biconvex positive lens, a positive lens having a convex surface facing the object side, and a positive meniscus lens having a convex surface facing the object side. A negative third lens unit G3 includes, in the following order from the object side, a cemented lens of a positive meniscus lens having a concave surface facing the object side and a negative lens having a concave surface facing the object side, and a biconcave negative lens. A positive fourth lens unit G4 includes, in the following order from the object side, a cemented lens of a negative lens having an aspherical surface on its object side and a biconvex positive lens. A stop S is located between the second and third lens units G2 and G3, and moves integrally with the third lens unit G3 upon zooming. 
     The data values and the condition corresponding values of the sixth embodiment will be summarized below. 
     
                       TABLE 6______________________________________Data Values of Sixth Embodimentf = 24.70 to 101.86F = 3.60 to 5.752ω = 85.2 to 23.8°   r         d           ν n______________________________________ 1      309.7833  2.0000      42.97                              1.83500 2      26.6425   6.7487 3*     71.7975   2.0000      70.45                              1.48749 4      27.5830   6.9066      23.83                              1.84666 5      48.3051   D5 6      29.5142   1.1000      23.83                              1.84666 7      20.0870   5.9407      70.45                              1.48749 8      -736.3842 0.1000 9      43.7188   3.3090      64.20                              1.5168010      745.4483  0.100011      32.9068   3.6236      70.45                              1.4874912      191.0314  D1213      (stop)    1.500014      -55.8199  3.0283      25.46                              1.8051815      -21.9569  1.0000      56.27                              1.5013716      447.9461  0.689617      -93.6497  1.1000      46.54                              1.8158418      62.4718   D18 19*    101.1392  1.2000      23.83                              1.8466620      29.7281   5.0317      47.50                              1.7880021      -110.1780 BfThird Surface Aspherical Surface Coefficientsk = 1.000          C4 = 0.4748 × 10.sup.-5C6 = 0.1037 × 10.sup.-7              C8 = -0.1861 × 10.sup.-10C10 = 0.3579 × 10.sup.-1319th Surface Aspherical Surface Coefficientsk = 1.000          C4 = -0.1022 × 10.sup.-4C6 = -0.1679 × 10.sup.-7              C8 = 0.1558 × 10.sup.-10C10 = -0.1542 × 10.sup.-12Change in Interval Upon Zoomingf        24.6961       48.9889 101.8571D5       54.1778       18.1640 2.0000D12      2.5000        7.3623  10.5888D18      14.9439       8.3828  2.0000Bf       38.0902       55.7969 100.0880Condition Corresponding Values  (7)  f1/fT = -0.374  (8)  f3/fW = -1.701  (9)  f4/fW = 3.023  (10) f3/f1 = 1.103  (11) B2T/B2W = 3.301  (12) f1 - 3W/fW = 2.144  (13) f1 - 3T/f1 = 7.349  (14) T4/fT = 0.061  (15) nN - nP = 0.05866  (16) νP - νN = 23.67  (17) (nF - nR) · A(Y/3) = 0.0252  (18) A(Y/3)/A(Y/4) = 3.269______________________________________ 
    
     [Seventh Embodiment] 
     In the seventh embodiment, as shown in FIG. 7, a negative first lens unit G1 includes, in the following order from the object side, a biconcave negative lens having an aspherical surface on its image side, and a cemented lens of a biconvex positive lens and a biconcave negative lens. A positive second lens unit G2 includes, in the following order from the object side, a cemented lens of a negative meniscus lens having a convex surface facing the object side and a biconvex positive lens, a cemented lens of a biconvex positive lens and a negative meniscus lens having a concave surface facing the object side, and a biconvex positive lens. A negative third lens unit G3 includes, in the following order from the object side, a cemented lens of a positive meniscus lens having a concave surface facing the object side and a biconcave negative lens, and a negative lens having a concave surface facing the object side. A positive fourth lens unit G4 includes, in the following order from the object side, a biconvex positive lens having an aspherical surface on its image side, and a negative meniscus lens having a concave surface facing the object side. A stop S is located between the second and third lens units G2 and G3, and moves integrally with the third lens unit G3 upon zooming. 
     The data values and the condition corresponding values of the seventh embodiment will be summarized below. 
     
                       TABLE 7______________________________________Data Values of Seventh Embodimentf = 24.70 to 117.00F = 3.81 to 5.832ω = 85.8 to 20.6°   r         d           ν n______________________________________ 1      -201.6716 1.7000      45.06                              1.74400 2*     26.9346   4.8095 3      50.6776   6.5000      25.36                              1.80518 4      -208.1603 1.5000      60.35                              1.62041 5      39.5855   D5 6      38.8378   1.0000      25.36                              1.80518 7      26.9488   5.4843      70.24                              1.48749 8      -319.9544 0.1000 9      41.0170   6.6185      70.24                              1.4874910      -37.0346  1.0000      36.54                              1.8306011      -133.8048 0.100012      42.6802   3.8492      60.35                              1.6204113      -375.5904 D1314      (stop)    1.500015      -107.5493 3.0270      27.64                              1.7552016      -25.6650  1.0000      54.62                              1.5145417      56.8089   1.663818      -60.2616  1.0000      45.06                              1.7440019      417.0931  D1920      50.0836   4.2300      70.45                              1.48749 21*    -35.4440  0.800022      -30.7404  1.0000      25.36                              1.8051823      -52.3046  BfSecond Surface Aspherical Surface Coefficientsk = 1.000          C4 = -0.8887 × 10.sup.-5C6 = -0.6719 × 10.sup.-8              C8 = 0.1400 × 10.sup.-11C10 = -0.1320 × 10.sup.-1321st Surface Aspherical Surface Coefficientsk = 1.000          C4 = 0.1593 × 10.sup.-4C6 = 0.1829 × 10.sup.-7              C8 = -0.1448 × 10.sup.-10C10 = 0.1429 × 10.sup.-12Change in Interval Upon Zoomingf        24.6998       48.9994 116.9981D5       47.9962       17.2434 0.8820D13      0.8807        8.3246  27.0244D19      19.6307       11.4171 0.9108Bf       37.9344       56.4139 93.5704Condition Corresponding Values  (7)  f1/fT = -0.276  (8)  f3/fW = -1.915  (9)  f4/fW = 3.157  (10) f3/f1 = 1.467  (11) B2T/B2W = 4.133  (12) f1 - 3W/fW = 2.134  (13) f1 - 3T/f1 = 14.81  (14) T4/fT = 0.052  (15) nN - nP = 0.31769  (16) νP - νN = 45.09  (17) (nF - nR) · A(Y/3) = 0.0221  (18) A(Y/3)/A(Y/4) = 3.239______________________________________ 
    
     [Eighth Embodiment] 
     In the eighth embodiment, as shown in FIG. 8, a negative first lens unit G1 includes, in the following order from the object side, a biconcave negative lens having an aspherical surface on its image side, and a cemented lens of a biconvex positive lens and a biconcave negative lens. A positive second lens unit G2 includes, in the following order from the object side, a cemented lens of a negative meniscus lens having a convex surface facing the object side and a positive lens, a cemented lens of a biconvex positive lens and a negative meniscus lens having a concave surface facing the object side, and a positive lens having a convex surface facing the object side. A negative third lens unit G3 includes, in the following order from the object side, a cemented lens of a positive meniscus lens having a concave surface facing the object side and a biconcave negative lens, and a biconcave negative lens. A positive fourth lens unit G4 includes, in the following order from the object side, a biconvex positive lens having an aspherical surface on its object side, and a negative meniscus lens having a concave surface facing the object side. A stop S is located between the second and third lens units G2 and G3, and moves integrally with the third lens unit G3 upon zooming. 
     The data values and the condition corresponding values of the eighth embodiment will be summarized below. 
     
                       TABLE 8______________________________________Data Values of Eighth Embodimentf = 24.70 to 117.00F = 3.64 to 5.712ω = 85.7 to 20.6°   r         d           ν n______________________________________ 1      -185.4736 1.7000      45.06                              1.74400 2*     29.0248   4.8095 3      52.7710   6.5000      25.36                              1.80518 4      -185.9420 1.5000      60.35                              1.62041 5      37.3660   D5 6      40.9787   1.0000      25.36                              1.80518 7      26.5733   5.4843      70.24                              1.48749 8      -946.8218 0.1000 9      43.5588   6.6185      70.24                              1.4874910      -37.4191  1.0000      36.54                              1.8306011      -102.2475 0.100012      37.0885   3.8492      60.35                              1.6204113      -2401.0895             D1314      (stop)    1.500015      -313.1685 3.0270      27.64                              1.7552016      -27.1198  1.0000      54.62                              1.5145417      55.5144   1.663818      -50.6068  1.0000      45.06                              1.7440019      209.4798  D19 20*    81.0024   5.0000      70.45                              1.4874921      -23.8966  1.335022      -20.6375  1.5000      25.36                              1.8051823      -32.4297  BfSecond Surface Aspherical Surface Coefficientsk = 1.000          C4 = -0.7932 × 10.sup.-5C6 = -0.7413 × 10.sup.-8              C8 = 0.9211 × 10.sup.-11C10 = -0.1430 × 10.sup.-1320th Surface Aspherical Surface Coefficientsk = 1.000          C4 = -0.1262 × 10.sup.-4C6 = -0.4082 × 10.sup.-9              C8 = -0.9722 × 10.sup.-10C10 = 0.2199 × 10.sup.-12Change in Interval Upon Zoomingf        24.6998       48.9996 116.9986D5       47.8760       17.1232 0.7618D13      0.4945        7.9384  26.6382D19      19.1580       10.9444 0.4381Bf       37.8726       56.3523 93.5090Condition Corresponding Values  (7)  f1/fT = -0.276  (8)  f3/fW = -1.915  (9)  f4/fW = 3.157  (10) f3/f1 = 1.467  (11) B2T/B2W = 4.133  (12) f1 - 3W/fW = 2.134  (13) f1 - 3T/f1 = 14.81  (14) T4/fT = 0.067  (15) nN - nP = 0.31769  (16) νP - νN = 45.09  (17) (nF - nR) · A(Y/3) = 0.0169  (18) A(Y/3)/A(Y/4) = 3.200______________________________________ 
    
     [Ninth Embodiment] 
     In the ninth embodiment, as shown in FIG. 9, a negative first lens unit G1 includes, in the following order from the object side, a biconcave negative lens having an aspherical surface on its image side, and a cemented lens of a biconvex positive lens and a biconcave negative lens. A positive second lens unit G2 includes, in the following order from the object side, a cemented lens of a negative meniscus lens having a convex surface facing the object side and a biconvex positive lens, a cemented lens of a biconvex positive lens and a negative meniscus lens having a concave surface facing the object side, and a biconvex positive lens. A negative third lens unit G3 includes, in the following order from the object side, a cemented lens of a positive meniscus lens having a concave surface facing the object side and a biconcave negative lens, and a biconcave negative lens. A positive fourth lens unit G4 includes, in the following order from the object side, a biconvex positive lens having an aspherical surface on its object side, and a negative meniscus lens having a concave surface facing the object side. A stop S is located between the second and third lens units G2 and G3, and moves integrally with the third lens unit G3 upon zooming. 
     The data values and the condition corresponding values of the ninth embodiment will be summarized below. 
     
                       TABLE 9______________________________________Data Values of Ninth Embodimentf = 24.70 to 116.99F = 3.53 to 5.6985.9 to 20.6°   r         d           ν n______________________________________ 1      -102.5666 2.0000      45.01                              1.74400 2*     27.7615   2.7000 3      47.1181   9.2000      25.46                              1.80518 4      -127.4792 2.0000      60.35                              1.62041 5      41.1160   D5 6      43.0100   1.3000      25.46                              1.80518 7      27.5706   6.0000      70.24                              1.48749 8      -125.6222 0.1000 9      48.6040   7.0000      70.24                              1.4874910      -34.6797  1.3000      36.54                              1.8306011      -104.3509 0.100012      41.6905   5.0000      60.35                              1.6204113      -378.6553 D1314      (stop)    1.500015      -310.6938 3.5000      27.64                              1.7552016      -25.7149  1.1000      54.62                              1.5145417      43.2109   1.800018      -44.4130  1.1000      45.06                              1.7440019      222.7680  D19 20*    76.1804   7.0000      70.45                              1.4874921      -22.9066  1.000022      -20.1997  1.5000      25.36                              1.8051823      -28.6184  BfSecond Surface Aspherical Surface Coefficientsk = 1.000          C4 = -0.1073 × 10.sup.-4C6 = -0.6607 × 10.sup.-8              C8 = 0.8487 × 10.sup.-11C10 = -0.1739 × 10.sup.-1320th Surface Aspherical Surface Coefficientsk = 1.000          C4 = -0.9966 × 10.sup.-5C6 = -0.2058 × 10.sup.-7              C8 = 0.1242 × 10.sup.-9C10 = -0.2184 × 10.sup.-12Change in Interval Upon Zoomingf        24.6997       48.9995 116.9947D5       47.8052       16.5638 1.0000D13      1.0000        9.0924  27.4128D19      20.9948       11.0192 1.0000Bf       38.0994       56.5808 95.4826Condition Corresponding Values  (7)  f1/fT = -0.269  (8)  f3/fW = -1.604  (9)  f4/fW = 2.494  (10) f3/f1 = 1.260  (11) B2T/B2W = 4.172  (12) f1 - 3W/fW = 3.001  (13) f1 - 3T/f1 = 6.221  (14) T4/fT = 0.081  (15) nN - nP = 0.31769  (16) νP - νN = 45.09  (17) (nF - nR) · A(Y/3) = 0.0141  (18) A(Y/3)/A(Y/4) = 3.239______________________________________ 
    
     FIGS. 10, 13, 16, 19, 22, 25, 28, 31, and 34 respectively show graphs of various aberrations at the wide-angle end of the first to ninth embodiments, FIGS. 11, 14, 17, 20, 23, 26, 29, 32, and 35 respectively show graphs of various aberrations in an intermediate focal length state of the first to ninth embodiments, and FIGS. 12, 15, 18, 21, 24, 27, 30, 33, and 36 respectively show graphs of various aberrations at the telephoto end of the first to ninth embodiments. In each of these graphs, H is the incident light height, Y is the image height, d is the d-line (λ=587.6 nm), and g is the g-line (λ=435.8 nm). In each graph showing astigmatism, a dotted curve represents the meridional image surface, and a solid curve represents the sagittal image surface. 
     As can be seen from these graphs, in each of the above embodiments, various aberrations are satisfactorily corrected, and good imaging performance can be obtained. 
     As described above, according to the present invention, a compact zoom lens which has a field angle, at the wide-angle end, of 80° or more, a zoom ratio of ×4 or more, and good imaging performance, can be provided. 
     An image can be deflected by moving one of the first to fourth lens units or a portion of one of these lens units in a direction perpendicular to the optical axis, and hence, the present invention can be applied to an image stabilizing optical system. Focusing is preferably attained by moving the first lens unit. Alternatively, focusing may be attained by moving the third or fourth lens unit.