Abstract:
A zoom lens system has, from the object side to the image side, a first lens unit of positive power, a second lens unit of positive power and a third lens unit of negative power. Each lens unit has two lens elements. The air space between the first and second lens units and the air space between the second and third lens units are varied during a zooming operation. The zoom lens system fulfills the following condition: ##EQU1## Here, f1 is a focal length of the first lens unit and fW is a focal length of the entire lens system at the shortest focal length condition.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a high-magnification zoom lens system, and more specifically, to a high-magnification zoom lens system for use in a lens shutter camera. 
     2. Description of the Prior Art 
     Optical systems for use in lens shutter cameras are required to be compact and of high magnification. In recent years, high magnification is particularly required for such optical systems. 
     In order to realize a compacter lens system, in Japanese Laid-open Patent Application No. H3-127012, an arrangement is proposed having four lens elements grouped into two units with a zoom ratio of approximately 2 to 2.5×. In order to realize a higher magnification, three-unit zoom lens systems of positive, positive, negative configuration have been used since they are advantageous in performance correction and the amount of lens movement is small. 
     However, if a zoom ratio of 2.5 to 3× or higher is achieved in the two-unit, four-lens-element arrangement of Japanese Laid-open Patent Application No. H3-127012, it is difficult to secure a required performance, and the amount of lens movement is large. Consequently, it is impossible to realize a compact, high-magnification optical system. 
     In the above-mentioned three-unit zoom lens systems of positive, positive, negative configuration, because of the arrangement thereof, plus distortion is apt to be generated at a shorter focal length condition. Restraining this is one of the problems in designing such lens systems. Moreover, in positive first lens units of the three-unit lens systems of positive, positive, negative configuration, it is typical that the most object side lens element is convex to the object side. For this reason, more number of lens elements are required in order to correct the plus distortion generated at a shorter focal length condition. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a compact, low-cost, high-magnification zoom lens system with a zoom ratio of 2.5× or higher. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This and other objects and features of this invention will become clear from the following description, taken in conjunction with the preferred embodiments with reference to the accompanied drawings in which: 
     FIG. 1 is a cross-sectional view showing the lens arrangement of a first embodiment of the present invention; 
     FIG. 2 is a cross-sectional view showing the lens arrangement of a second embodiment of the present invention; 
     FIG. 3 is a cross-sectional view showing the lens arrangement of a third embodiment of the present invention; 
     FIG. 4 is a cross-sectional view showing the lens arrangement of a fourth embodiment of the present invention; 
     FIG. 5 is a cross-sectional view showing the lens arrangement of a fifth embodiment of the present invention; 
     FIG. 6 is a cross-sectional view showing the lens arrangement of a sixth embodiment of the present invention; 
     FIG. 7 is a cross-sectional view showing the lens arrangement of a seventh embodiment of the present invention; 
     FIG. 8 is a cross-sectional view showing the lens arrangement of an eighth embodiment of the present invention; 
     FIGS. 9A to 9I show aberration curves of the first embodiment of the present invention; 
     FIGS. 10A to 10I show aberration curves of the second embodiment of the present invention; 
     FIGS. 11A to 11I show aberration curves of the third embodiment of the present invention; 
     FIGS. 12A to 12I show aberration curves of the fourth embodiment of the present invention; 
     FIGS. 13A to 13I show aberration curves of the fifth embodiment of the present invention; 
     FIGS. 14A to 14I show aberration curves of the sixth embodiment of the present invention; 
     FIGS. 15A to 15I show aberration curves of the seventh embodiment of the present invention; and 
     FIGS. 16A to 16I show aberration curves of the eighth embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the present invention, in order to realize a compact, high-magnification zoom lens system, a three-unit arrangement of positive, positive, negative configuration is employed. Specifically, the following arrangement is employed since in order to realize a compact zoom lens system, it is required to minimize the number of lens elements in each lens unit, particularly, to minimize the number of lens elements of the positive first lens unit which has a relatively large outside lens diameter. 
     A first implementation of a high-magnification zoom lens system according to the present invention comprises from the object side a positive first lens unit, a positive second lens unit and a negative third lens unit. Zooming is performed by varying the distance between each lens unit. The positive first lens unit includes two lens elements. The positive second lens unit and the negative third lens unit include at least two lens elements, respectively. Moreover, the following condition (1) is fulfilled: ##EQU2## where f1 represents a focal length of the positive first lens unit, and fW represents a focal length of the entire lens system at the shortest focal length condition. 
     The condition (1) limits the power of the positive first lens unit. If the power of the positive first lens unit is strong, the power of the positive second lens unit must be weak relatively thereto. This is because if both the power of the positive first lens unit and the power of the positive second lens unit are strong, a sufficient performance correction and a sufficient back focal length are incompatible with each other. Specifically, if f1/fW exceeds the lower limit of the condition (1), the back focal length is short at the shortest focal length condition. Since it is necessary to increase the effective aperture of the positive first lens unit in order to secure a sufficient off-axial illumination at the shortest focal length condition, it is impossible to provide an optical system whose size along the diameter is small. 
     If the power of the positive first lens unit is weak, the movement amount of each lens unit should be large, and the aberration performance thereof is close to the aberration performance of two-unit lens systems of positive, negative configuration. Specifically, if f1/fW exceeds the upper limit of the condition (1), merits presented by the three-unit arrangement cannot be obtained. As a result, it is impossible to realize a high magnification. 
     Preferably, the lower limit of the above-described condition (1) is 3.0 as shown in the following condition (1&#39;): ##EQU3## 
     Further, by providing the following arrangements to the optical system fulfilling the condition (1), a compact, high-magnification zoom lens system can be realized: zooming from the shortest focal length condition to a longest focal length condition is performed by moving each lens unit so that the distance between the positive first lens unit and the positive second lens unit increases and that the distance between the positive second lens unit and the negative third lens unit decreases, and the following condition (2) is fulfilled: ##EQU4## where f2 represents a focal length of the positive second lens unit. 
     As described above, in optical systems of this type, in order to secure a sufficient illumination and a sufficient performance, it is important that the power of the positive first lens unit and the power of the positive second lens unit are appropriately balanced. Specifically, if f1/f2 exceeds the lower limit of the condition (2), the power of the positive first lens unit is relatively strong, so that it is difficult to secure a sufficient back focal length and a sufficient off-axial illumination at the shortest focal length condition. If f1/f2 exceeds the upper limit of the condition (2), the power of the positive first lens unit is relatively weak, so that the merit of the three-unit arrangement that the amount of lens movement is small is not obtained and the aberration performance thereof is close to the aberration performance of the two-unit arrangement. As a result, the object of the present invention cannot be achieved. 
     Further, by providing the following arrangement to the optical system fulfilling the condition (2), a compact, high-performance, high-magnification zoom lens system can be realized: from the object side, the positive first lens unit includes a negative lens element and a positive lens element, the positive second lens unit includes a negative lens element and a positive lens element and the negative third lens unit includes a positive lens element and a negative lens element, and at least one aspherical surface is provided in the positive second lens unit and the negative third lens unit. 
     With this arrangement where each lens unit includes two lens elements, the size and the cost can effectively be reduced. When the negative third lens unit is of positive, positive, negative lens element configuration, the problem of securing a sufficient back focal length at a shorter focal length condition is inevitably presented. In the present invention, this problem is solved by providing a retro-type arrangement (i.e. negative, positive lens element configuration) to the positive first and second lens units. 
     In order to secure an excellent performance with a minimum number of lens elements, at least one aspherical surface is provided in each of the positive second lens unit and the negative third lens unit. The aspherical surface of the positive second lens unit is used to correct spherical aberration, while the aspherical surface of the negative third lens unit is used to correct off-axial coma and distortion. That is, in order to secure a more excellent performance, it is preferable to arrange an aspherical surface in each of the positive second lens unit and the negative third lens unit. 
     Regarding the arrangement of the aspherical surfaces, by employing bi-aspherical lens elements as the negative lens element of the positive second lens unit and as the positive lens element of the negative third lens unit, a zoom lens system having a higher performance can be realized. While two or more lens elements are required to control principal aberrations such as spherical aberration, coma and distortion, by employing a bi-aspherical lens, the control can De performed with only one lens element, and furthermore, delicate control is possible. This largely contributes to the reduction of the size. 
     Moreover, if the movement loci of the positive first lens unit and the negative third lens unit are the same, the movements of both lens units can be generated by the same cam. This leads to a simple arrangement, thereby reducing the cost. 
     A second implementation of the high-magnification zoom lens system according to the present invention comprises from the object side a positive first lens unit, a positive second lens unit and a negative third lens unit. Zooming is performed by varying the distance between each lens unit. The most object side lens element of the positive first lens unit is a negative lens element whose object side surface has a stronger negative refractive power than an image side surface. With this arrangement, a compact, low-cost, high-magnification zoom lens system can be realized. 
     By employing a negative lens element strongly concave to the object side as the most object side negative lens element of the positive first lens unit, the plus distortion generated at a shorter focal length condition can be corrected. As a result, a high-magnification zoom lens system having an excellent performance is realized. 
     Further, by employing a negative meniscus lens element as the most object side negative lens element of the positive first lens unit in the second implementation of the high-magnification zoom lens system according to the present invention, a high-magnification zoom lens system having a more excellent performance can be realized. 
     If a bi-concave lens element is employed as the most object side lens element of the positive first lens unit, negative power increases in the positive first lens unit, so that it is impossible to correct spherical aberration within the positive first lens unit. This problem is solved by increasing the number of lens elements in the positive first lens unit; however, this contradicts the reduction in size and cost. In this implementation, by employing a negative meniscus lens element as the most object side lens element of the positive first lens unit, simultaneous correction of distortion and spherical aberration is enabled. 
     Further, by providing the following arrangements to the above-described arrangement where the most object side lens element of the positive first lens unit is a negative meniscus lens element, a high-magnification zoom lens system having a more excellent performance can be realized: the most object side lens element of the positive first lens element is concave to the object side, and the following condition (3) is fulfilled: ##EQU5## where r1 represents a radius of curvature of the most object side surface of the positive first lens unit. 
     If |r1|/f1 exceeds the lower limit of the condition (3), the luminous fluxes incident on the first surface are caused to spring up largely, so that it is difficult to secure a sufficient performance. If |r1|/f1 exceeds the upper limit of the condition (3), the effect of correcting distortion is diminished. 
     The condition (3) limits the configuration of the most object side surface of the positive first lens unit. In order to secure a more excellent performance, the curvature, i.e. the meniscus degree of the film side surface of a first lens element (the most object side lens element of the positive first lens unit) is an important factor. 
     For example, an arrangement fulfilling the following condition (4) is preferable in securing a higher optical performance: ##EQU6## where r2 represents a radius of curvature of the film side surface of the most object side lens element of the positive first lens unit. 
     If the lower limit of the condition (4) is exceeded, it is necessary to increase the number of lens elements in order to eliminate aberrations within the positive first lens unit. When the upper limit of the condition (4) is exceeded, the effect of correcting distortion by the first surface is decreased, so that it is difficult to realize an excellent performance. 
     Preferably, the lower limit of the above-described condition (4) is 2.5 as shown in the following condition (4&#39;): ##EQU7## 
     Moreover, the following conditions (5) and (6) are preferably fulfilled: ##EQU8## where fT represents a focal length of the entire lens system at the longest focal length condition, and D1 represents the total length of the positive first lens unit. 
     The condition (5) limits the power of the positive first lens unit. If the power of the positive first lens unit is strong, the power of the positive second lens unit must be weak relatively thereto. This is because if both the power of the positive first lens unit and the power of the positive second lens unit are strong, a sufficient performance correction and a sufficient back focal length are incompatible with each other. Specifically, if f1.fT/fW exceeds the lower limit of the condition (5), the back focal length at the shortest focal length condition is short. Since it is necessary to increase the effective aperture of the positive first lens unit in order to secure a sufficient off-axial illumination at the shortest focal length condition, it is impossible to realize a zoom lens system whose size along the diameter is small. 
     If the power of the positive first lens unit is weak, the movement amount of each lens unit should be large, and the aberration performance thereof is close to the aberration performance of the two-unit lens systems of positive, negative configuration. Specifically, if f1.fT/fW exceeds the upper limit of the condition (5), merits presented by the three-unit arrangement cannot be obtained. As a result, it is impossible to realize a high magnification. 
     If the upper value of the condition (6) is exceeded, the size of the positive first lens unit should be large, so that it is difficult to reduce the size. Moreover, since the focal length of the positive first lens unit is short, aberration correction is difficult. If the lower limit of the condition (6) is exceeded, the focal length of the positive first lens unit is long, so that the lens movement amount for zooming is large. Moreover, it is impossible to secure sufficient holding portions at the peripheries of the lens elements constituting the positive first lens unit. 
     Numerical data of first to eighth embodiments of the present invention are shown in Tables 1 to 8, respectively. In each table, ri (i=1,2,3, . . . ) represents a radius of curvature of an ith lens surface counted from the object side, di (i=1,2,3, . . . ) represents an ith axial distance counted from the object side, Ni (i=1,2,3, . . . ) and vi (i=1,2,3, . . . ) represent a refractive index and an Abbe number, to the d-line, of an ith lens element counted from the object side, respectively. f represents a focal length of the entire lens system. FNO represents a minimum f-number. 
     In each table, surfaces marked with asterisks are aspherical surfaces, which are defined by the following equation (7): ##EQU9## where X represents a displacement amount from a reference surface along the optical axis, Y represents a height in a direction perpendicular to the optical axis, C represents a paraxial curvature, ε represents a conic constant, and Ai represents an lth-order aspherical coefficient. 
     FIGS. 1 to 8 are cross-sectional views showing the lens arrangements of the first to eighth embodiments, respectively, at the shortest focal length condition (W). Arrows m1, m2 and m3 schematically show the movement loci of the first, second and third lens units Gr1, Gr2 and Gr3, respectively, from the shortest focal length condition (W) to the longest focal length condition (T). The numerical values next to m1, m2 and m3 are movement amounts of the lens units Gr1, Gr2 and Gr3. 
     The first embodiment comprises from the object side a positive first lens unit Gr1 including a negative meniscus lens element concave to the object side and a positive bi-convex lens element, a positive second lens unit Gr2 including a negative meniscus lens element concave to the image side, a positive meniscus lens element convex to the image side and an aperture stop A, and a negative third lens unit Gr3 including a positive meniscus lens element convex to the image side and a negative meniscus lens element concave to the object side. 
     In the first embodiment, the following surfaces are aspherical: the object side surface of the negative meniscus lens element and the object side surface of the positive lens element of the positive first lens unit Gr1; both side surfaces of the negative meniscus lens element of the positive second lens unit Gr2; and both side surfaces of the positive meniscus lens element of the negative third lens unit Gr3. 
     The second embodiment comprises from the object side a positive first lens unit Gr1 including a negative meniscus lens element concave to the object side and a positive bi-convex lens element, a positive second lens unit Gr2 including a negative meniscus lens element concave to the image side, a positive bi-convex lens element and an aperture stop A, and a negative third lens unit Gr3 including a positive meniscus lens element convex to the image side and a negative meniscus lens element concave to the object side. 
     In the second embodiment, the following surfaces are aspherical: both side surfaces of the negative meniscus lens element of the positive second lens unit Gr2; and both side surfaces of the positive meniscus lens element of the negative third lens unit Gr3. 
     The third embodiment comprises from the object side a positive first lens unit Gr1 including a negative meniscus lens element concave to the object side and a positive bi-convex lens element, a positive second lens unit Gr2 including a negative meniscus lens element concave to the image side, a positive bi-convex lens element and an aperture stop A, and a negative third lens unit Gr3 including a positive meniscus lens element convex to the image side and a negative meniscus lens element concave to the image side. 
     In the third embodiment, the following surfaces are aspherical: the object side surface of the positive lens element of the positive first lens unit Gr1; both side surfaces of the negative meniscus lens element of the positive second lens unit Gr2; and both side surfaces of the positive meniscus lens element of the negative third lens unit Gr3. 
     The fourth embodiment comprises from the object side a positive first lens unit Gr1 including a negative meniscus lens element concave to the object side and a positive meniscus lens element convex to the object side, a positive second lens unit Gr2 including a negative meniscus lens element concave to the image side, a positive bi-convex lens element and an aperture stop A, and a third lens unit Gr3 including a positive meniscus lens element convex to the image side and a negative meniscus lens element concave to the object side. 
     In the fourth embodiment, the following surfaces are aspherical: the object side surface of the positive meniscus lens element of the positive first lens unit Gr1; both side surfaces of the negative meniscus lens element of the positive second lens unit Gr2; and both side surfaces of the positive meniscus lens element of the negative third lens unit Gr3. 
     The fifth embodiment comprises from the object side a positive first lens unit Gr1 including a negative meniscus lens element concave to the object side and a positive bi-convex lens element, a positive second lens unit Gr2 including a positive meniscus lens element convex to the object side, a negative bi-concave lens element and an aperture stop A, and a negative third lens unit Gr3 including a positive meniscus lens element convex to the image side and a negative bi-concave lens element. 
     In the fifth embodiment, the following surfaces are aspherical: the object side surface of the positive lens element of the positive first lens unit Gr1; the object side surface of the positive meniscus lens element convex to the image side of the positive second lens unit Gr2; and both side surfaces of the positive meniscus lens element of the third lens unit Gr3. 
     The sixth embodiment comprises from the object side a positive first lens unit Gr1 including a negative meniscus lens element concave to the object side and a positive meniscus lens element convex to the image side, a positive second lens unit Gr2 including a negative meniscus lens element concave to the image side, a positive bi-convex lens element and an aperture stop A, and a negative third lens unit Gr3 including a positive meniscus lens element convex to the image side and two negative meniscus lens elements concave to the object side. 
     In the sixth embodiment, the following surfaces are aspherical: the object side surface of the positive meniscus lens element of the positive first lens unit Gr1; both side surfaces of the negative meniscus lens element of the positive second lens unit Gr2; and both side surfaces of the positive meniscus lens element of the negative third lens unit Gr3. 
     The seventh embodiment comprises from the object side a positive first lens unit Gr1 including a negative meniscus lens element concave to the object side and a positive meniscus lens element convex to the image side, a positive second lens unit Gr2 including a negative meniscus lens element concave to the image side, a positive bi-convex lens element and an aperture stop A, and a negative third lens unit Gr3 including a positive meniscus lens element convex to the image side and a negative meniscus lens element concave to the object side. 
     In the seventh embodiment, the following surfaces are aspherical: both side surfaces of the negative meniscus lens element of the positive second lens unit Gr2; and both side surfaces of the positive meniscus lens element of the negative third lens unit Gr3. 
     The eighth embodiment comprises from the object side a positive first lens unit Gr1 including a negative meniscus lens element concave to the object side and a positive meniscus lens element convex to the object side, a positive second lens unit Gr2 including a negative meniscus lens element concave to the image side, a positive meniscus lens element convex to the image side and an aperture stop A, and a negative third lens unit Gr3 including two negative meniscus lens elements concave to the object side. 
     In the eight embodiment, the following surfaces are aspherical: the object side surface of the negative meniscus lens element and the object side surface of the positive meniscus lens element of the positive first lens unit Gr1; both side surfaces of the negative meniscus lens element of the positive second lens unit Gr2; and both side surfaces of the object side negative meniscus lens element of the negative third lens unit Gr3. 
     FIGS. 9A to 9I through 16A to 16I show aberration curves of the first to eighth embodiments. In each figure, (W) shows aberration at the shortest focal length condition, (M) shows aberration at the middle focal length condition, and (T) shows aberration at the longest focal length condition. Solid line d represents aberrations to d-line. Broken line SC represents sine condition. Broken line DM and solid line DS represent astigmatism on the meridional and sagittal surfaces, respectively. 
     Table 9 shows values of f1/fW and f1/f2 of the conditions (1) and (2) for the first to eighth embodiments. Table 10 shows values of |r1|/f1 and (r1+r2)/(r1-r2) of the conditions (3) and (4) for the first to eighth embodiments. Table 11 shows values of f1.fT/fW and D1/f1 of the conditions (5) and (6) for the first to eighth embodiment. 
     In the above-described embodiments, it is preferable that the following conditions (8) to (10) are further fulfilled: ##EQU10## where ω represents a half angle of view of the entire lens system at the shortest focal length condition, and y&#39; represents a maximum image height. 
     The conditions (8) and (10) define an appropriate power of the first lens unit similarly to the conditions, (1) and (5). The condition (9) defines an appropriate shortest focal length condition (shortest focal length). 
     As is clear from the above-mentioned embodiments, according to the present invention, a compact, low-cost, high-magnification zoom lens system with a zoom ratio of 2.5× or higher is realized. Particularly, by providing a zoom ratio of 2.5 to 3× or higher and minimizing the number of lens elements and the lens diameter, a compact, low-cost zoom lens system having a high performance is realized. Specifically, by minimizing the number of lens elements of the positive first lens unit and providing a novel characteristic to the most object side lens element of the positive first lens unit, an excellent aberration performance is realized with a simple arrangement where the number of lens elements are minimized. The total length and the diameter of the front lens element are much smaller than those of conventional lens systems. Thus, the present invention satisfactorily achieve the object thereof. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically described. 
     
                       TABLE 1______________________________________(1st Embodiment)f = 39.3 to 55.0 to 102.1         FNO = 3.62 to 4.75 to 8.04Radius of  Axial      Refractive  AbbeCurvature  Distance   Index       Number______________________________________r1*   -24.637          d1      1.500                       N1    1.80741                                   ν1                                        31.59r2    -32.135          d2      0.500r3*   38.081          d3      2.000                       N2    1.51680                                   ν2                                        64.20r4    -177.382    d4    1.500 to 6.815 to 13.574r5*   22.727          d5      2.500                       N3    1.84506                                   ν3                                        23.66r6*   17.030          d6      4.276r7    -727.876          d7      4.900                       N4    1.52307                                   ν4                                        58.57r8    -14.259          d8      2.200r9    ∞ (Aperture stop)          d9      14.148 to 8.833 to 2.074r10*  -25.302           d10    2.758                       N5    1.58340                                   ν5                                        30.23r11   -20.895           d11    3.298r12   -13.697           d12    1.000                       N6    1.67790                                   ν6                                        55.38r13   -124.022Aspherical Coefficientsr1   :ε = 0.10000 × 10A4 = 0.22545 × 10.sup.-5A6 = 0.41368 × 10.sup.-7A8 = -0.95522 × 10.sup.-10A10 = -0.24177 × 10.sup.-12A12 = -0.17429 × 10.sup.-14r3   :ε =  0.10000 × 10A4 = 0.35042 × 10.sup.-5A6 =  0.26666 × 10.sup.-7A8 = -0.59025 × 10.sup.-9A10 = -0.25201 × 10.sup.-11A12 = 0.54898 × 10.sup.-13r5   :ε = 0.10000 × 10A4 = -0.12417 × 10.sup.-3A6 = -0.97074 × 10.sup.-6A8 = 0.12044 × 10.sup.-8A10 = 0.66132 × 10.sup. -10A12 = -0.15556 × 10.sup.-11r6   :ε = 0.10000 × 10A4 = -0.10076 × 10.sup.-3A6 = -0.14758 × 10.sup.-5A8 = 0.24553 × 10.sup.-7A10 = -0.21049 × 10.sup.-9A12 = -0.16260 × 10.sup.-11A14 = 0.65829 × 10.sup.-15A16 = 0.58947 × 10.sup.-16r10  :ε = 0.10000 × 10A3 = -0.42559 × 10.sup.-3A4 = 0.24350 × 10.sup.-3A5 = -0.41374 × 10.sup.-4A6 = 0.44517 × 10.sup.-5A7 = 0.73797 × 10.sup.-7A8 = -0.45062 × 10.sup.-7A9 = -0.42551 × 10.sup.-9A10 = 0.33908 × 10.sup.-9A11 = 0.79128 × 10.sup.-11A12 = -0.20278 × 10.sup.-11A13 = 0.60303 × 10.sup.-15A14 = 0.64064 × 10.sup.-15A15 = 0.10109 × 10.sup.-15A16 = 0.11619 × 10.sup.-16r11  :ε = 0.10000 × 10A3 = -0.40645 × 10.sup.-3A4 = 0.14149 × 10.sup.-3A5 = -0.12074 × 10.sup.-4A6 = -0.24598 × 10.sup.-6A7 = 0.39639 × 10.sup.-7A8 = 0.41323 × 10.sup.-7A9 = -0.66676 × 10.sup.-8A10 = 0.10617 × 10.sup.-9A11 = 0.30611 × 10.sup.-10A12 = -0.13930 × 10.sup.-11A13 = -0.15678 × 10.sup.-14______________________________________ 
    
     
                       TABLE 2______________________________________(2nd Embodiment)f = 39.3 to 55.0 to 116.4         FNO = 3.62 to 4.89 to 9.78Radius of  Axial      Refraction  AbbeCurvature  Distance   Index       Number______________________________________r1    -17.326          d1      1.500                       N1    1.83400                                   ν1                                        37.05r2    -30.899          d2      1.000r3    1052.587          d3      2.000                       N2    1.51680                                   ν2                                        64.20r4    -20.348    d4    1.500 to 6.178 to 12.686r5*   19.265          d5      2.500                       N3    1.84666                                   ν3                                        23.82r6*   16.277          d6      4.705r7    209.666          d7      4.900                       N4    1.51680                                   ν4                                        64.20r8    -16.618          d8      2.200r9    ∞ (Aperture stop)    d9    13.260 to 8.583 to 2.074r10*  -40.629           d10    2.500                       N5    1.58340                                   ν5                                        30.23r11*  -21.069           d11    3.125r12   -12.170           d12    1.000                       N6    1.80100                                   ν6                                        46.54r13   -112.448Aspherical Coefficientsr5   :ε = 0.10000 × 10A4 = -0.97544 × 10.sup.-4A6 = -0.10716 × 10.sup.-5A8 = 0.10311 × 10.sup.-8A10 = 0.66101 × 10.sup.-10A12 = -0.15569 × 10.sup.-11r6   :ε = 0.10000 × 10A4 = -0.89731 × 10.sup.-4A6 = -0.17068 × 10.sup.-5A8 = 0.23481 × 10.sup.-7A10 = -0.21301 × 10.sup.-9A12 = -0.16296 × 10.sup.-11A14 = 0.65829 × 10.sup.-15A16 = 0.58947 × 10.sup.-16r10  :ε = 0.10000 × 10A3 = -0.48875 × 10.sup.-3A4 = 0.24712 × 10.sup.-3A5 = -0.41550 × 10.sup.-4A6 = 0.45239 × 10.sup.-5A7 = 0.79939 × 10.sup.-7A8 = -0.44781 × 10.sup.-7A9 = -0.42511 × 10.sup.-9A10 = 0.33770 × 10.sup.-9A11 = 0.79128 × 10.sup.-11A12 = -0.20467 × 10.sup.-11A13 = 0.60303 × 10.sup.-15A14 = 0.64064 × 10.sup.-15A15 = 0.10109 × 10.sup.-15A16 = 0.11619 × 10.sup.-16r11  :ε = 0.10000 × 10A3 = -0.46929 × 10.sup.-3A4 = 0.13287 × 10.sup.-3A5 = -0.12024 × 10.sup.-4A6 = -0.26548 × 10.sup.-6A7 = 0.40398 × 10.sup.-7A8 = 0.41554 × 10.sup.-7A9 = -0.67388 × 10.sup.- 8A10 = 0.11910 × 10.sup.-9A11 = 0.30611 × 10.sup.-10A12 = -0.15480 × 10.sup.-11A13 = -0.15678 × 10.sup.-14______________________________________ 
    
     
                       TABLE 3______________________________________(3rd Embodiment)f = 39.1 to 55.0 to 131.0         FNO = 3.62 to 4.94 to 11.24Radius of  Axial      Refraction  AbbeCurvature  Distance   Index       Number______________________________________r1    -23.671          d1      1.500                       N1    1.80741                                   ν1                                        31.59r2    -34.019          d2      1.500r3*   68.124          d3      2.000                       N2    1.51823                                   ν2                                        58.96r4    -65.497    d4    1.500 to 5.730 to 12.128r5*   19.271          d5      2.500                       N3    1.84666                                   ν3                                        23.82r6*   15.460          d6      4.669r7    93.387          d7      4.900                       N4    1.51680                                   ν4                                        64.20r8    -15.313          d8      2.200r9    ∞ (Aperture stop)          d9      12.702 to 8.472 to 2.074r10*  -28.022           d10    2.397                       N5    1.58340                                   ν5                                        30.23r11*  -18.622           d11    3.186r12   -11.005           d12    1.000                       N6    1.77250                                   ν6                                        49.77r13   -65.989Aspherical Coefficientsr3   :ε = 0.10000 × 10A4 = 0.71213 × 10.sup.-5A6 = 0.99367 × 10.sup.-7A8 = -0.73631 × 10.sup.-9A10 = -0.35881 × 10.sup.-11A12 = 0.42528 × 10.sup.-13r5   :ε = 0.10000 × 10A4 = -0.10518 × 10.sup.-3A6 = -0.10874 × 10.sup.-5A8 = 0.87759 × 10.sup.-9A10 = 0.65258 × 10.sup.-10A12 = -0.15595 × 10.sup.-11r6   :ε = 0.10000 × 10A4 = -0.89939 × 10.sup.-4A6 = -0.16247 × 10.sup.-5A8 = 0.23947 × 10.sup.-7A10 = -0.21136 × 10.sup.-9A12 = -0.16251 × 10.sup.-11A14 = 0.65829 × 10.sup.-15A16 = 0.58947 × 10.sup.-16r10  :ε = 0.10000 × 10A3 = -0.51959 × 10.sup.-3A4 = 0.24968 × 10.sup.-3A5 = -0.40581 × 10.sup.-4A6 = 0.46041 × 10.sup.-5A7 = 0.84834 × 10.sup.-7A8 = -0.44497 × 10.sup.-7A9 = -0.42511 × 10.sup.-9A10 = 0.33876 × 10.sup.-9A11 = 0.79128 × 10.sup.-11A12 = -0.20503 × 10.sup.-11A13 = 0.60303 × 10.sup.-15A14 = 0.64064 × 10.sup.-15A15 = 0.10109 × 10.sup.-15A16 = 0.11619 × 10.sup.-16r11  :ε = 0.10000 × 10A3 = -0.52687 × 10.sup.-3A4 = 0.13356 × 10.sup.-3A5 = -0.12412 × 10.sup.-4A6 = -0.30313 × 10.sup.-6A7 = 0.38692 × 10.sup.-7A8 = 0.39750 × 10.sup.-7A9 = -0.63909 × 10.sup.-8A10 = 0.14162 × 10.sup.-9A11 = 0.30611 × 10.sup.-10A12 = -0.19509 × 10.sup.-11A13 = -0.15678 × 10.sup.-14______________________________________ 
    
     
                       TABLE 4______________________________________(4th Embodiment)f = 39.3 to 55.0 to 102.1         FNO = 3.62 to 4.97 to 9.02Radius of  Axial      Refraction  AbbeCurvature  Distance   Index       Number______________________________________r1    -28.310          d1      1.500                       N1    1.80741                                   ν1                                        31.59r2    -34.946          d2      1.500r3*   40.812          d3      2.000                       N2    1.51680                                   ν2                                        64.20r4    92.711    d4    1.500 to 7.505 to 14.647r5*   22.815          d5      2.500                       N3    1.84506                                   ν3                                        23.66r6*   18.596          d6      3.865r7    223.647          d7      4.900                       N4    1.51728                                   ν4                                        69.43r8    -14.626          d8      2.200r9    ∞ (Aperture stop)          d9      15.221 to 9.216 to 2.074r10*  -25.824           d10    2.733                       N5    1.58340                                   ν5                                        30.23r11*  -21.854            d11   4.371r12   -14.698           d12    1.000                       N6    1.67000                                   ν6                                        57.07r13   -116.707Aspherical Coefficientsr3   :ε = 0.10000 × 10A4 = 0.80817 × 10.sup.-5A6 = 0.47524 × 10.sup.-7A8 = -0.90286 × 10.sup.-10A10 = -0.35563 × 10.sup.-11A12 = 0.40562 × 10.sup.-14r5   :ε = 0.10000 × 10A4 = -0.12769 × 10.sup.-3A6 = -0.10537 × 10.sup.-5A8 = 0.18690 × 10.sup.-8A10 = 0.71924 × 10.sup.-10A12 = -0.15257 × 10.sup.-11r6   :ε = 0.10000 × 10A4 = -0.10173 × 10.sup.-3A6 = -0.14103 × 10.sup.-5A8 = 0.24573 × 10.sup.-7A10 = -0.21112 × 10.sup.-9A12 = -0.16323 × 10.sup.-11A14 = 0.65829 × 10.sup.-15A16 = 0.58947 × 10.sup.-16r10  :ε = 0.10000 × 10A3 = -0.46759 × 10.sup.-3A4 = 0.24869 × 10.sup.-3A5 = -0.41484 × 10.sup.-4A6 = 0.44842 × 10.sup.-5A7 = 0.75332 × 10.sup.-7A8 = -0.45065 × 10.sup.-7A9 = -0.42511 × 10.sup.-9A10 = 0.33778 × 10.sup.-9A11 = 0.79128 × 10.sup.-11A12 = -0.20491 × 10.sup.-11A13 = 0.60303 × 10.sup.-15A14 = 0.64064 × 10.sup.-15A15 = 0.10109 × 10.sup.-15A16 = 0.11619 × 10.sup.-16r11  :ε = 0.10000 × 10A3 = -0.41109 ×  10.sup.-3A4 = 0.14450 × 10.sup.-3A5 = -0.11422 × 10.sup.-4A6 = -0.24553 × 10.sup.-6A7 = 0.40954 × 10.sup.-7A8 = 0.42801 × 10.sup.-7A9 = -0.67605 × 10.sup.-8A10 = 0.11349 × 10.sup.-9A11 = 0.30611 × 10.sup.-10A12 = -0.14557 × 10.sup.-11A13 = -0.15678 × 10.sup.-14______________________________________ 
    
     
                       TABLE 5______________________________________(5th Embodiment)______________________________________f = 39.1 to 55.0 to 116.4 FNO = 3.62 to 4.95 to 10.06Radius of Axial        Refractive AbbeCurvature Distance     Index      Number______________________________________r1   -19.626           d1     1.500 N1   1.80750                                    ν1                                        35.43r2   -32.104           d2     1.000r3*  143.565           d3     2.000 N2   1.51680                                    ν2                                        64.20r4   -29.168     d4   1.500 to 5.212 to 10.311r5   28.367           d5     4.247 N3   1.54072                                    ν3                                        47.22r6   253.548           d6     0.845r7   -69.892           d7     3.168 N4   1.80500                                    ν4                                        40.97r8   121.833           d8     2.500r9   ∞ (Aperture stop)           d9     2.600r10* -135.135           d10    2.173 N5   1.58400                                    ν5                                        31.00r11  -82.950           d11    3.027r12  67.090           d12    4.932 N6   1.49310                                    ν6                                        83.58r13  -19.492      d13 10.886 to 7.174 to 2.074.r14* -35.497           d14    2.335 N7   1.58340                                    ν7                                        30.23r15* -23.461           d15    3.211r16  -12.629           d16    1.000 N8   1.77250                                    ν8                                        49.77r17  829.579______________________________________Aspherical Coefficients______________________________________r3:         ε = 0.10000 × 10       A4 = 0.18053 × 10.sup.-5       A6 = 0.37365 × 10.sup.-6       A8 = -0.12463 × 10.sup.-7       A10 = 0.18326 × 10.sup.-9       A12 = -0.96454 × 10.sup.-12r10:        ε = 0.10000 × 10       A4 = -0.38629 × 10.sup.-4       A6 = -0.65195 × 10.sup.-6       A8 = 0.98473 × 10.sup.-8       A10 = -0.62355 × 10.sup.-11       A12 = -0.14515 × 10.sup.-12r14:        ε = 0.10000 × 10       A3 = -0.49848 × 10.sup.-3       A4 = 0.24903 × 10.sup.-3       A5 = -0.41162 × 10.sup.-4       A6 = 0.54818 × 10.sup.-5       A7 = 0.81797 × 10.sup.-7       A8 = -0.51475 × 10.sup.-7       A9 = -0.42511 × 10.sup.-9       A10 = 0.35170 × 10.sup.-9       A11 = 0.79128 × 10.sup.-11       A12 = -0.18239 × 10.sup.-11       A13 = 0.60303 × 10.sup.-15       A14 = 0.64064 × 10.sup.-15       A15 = 0.10109 × 10.sup.-15       A16 = 0.11619 × 10.sup.-16r15:        ε = 0.10000 × 10       A3 = -0.49448 × 10.sup.-3       A4 = 0.13310 × 10.sup.-3       A5 = -0.12134 × 10.sup.-4       A6 = -0.74522 × 10.sup.-6       A7 = 0.39796 × 10.sup.- 7       A8 = 0.31759 × 10.sup.-7       A9 = -0.66232 × 10.sup.-8       A10 = 0.19651 × 10.sup.-9       A11 = 0.30611 × 10.sup.-10       A12 = -0.16945 × 10.sup.-11       A13 = -0.15678 × 10.sup.-14______________________________________ 
    
     
                       TABLE 6______________________________________(6th Embodiment)______________________________________f = 39.1 to 55.0 to 116.4 FNO = 3.62 to 4.95 to 10.07Radius of Axial        Refractive AbbeCurvature Distance     Index      Number______________________________________r1   -16.094           d1     1.500 N1   1.80750                                    ν1                                        35.43r2   -31.747           d2     1.000r3*  -324.726           d3     2.000 N2   1.51680                                    ν2                                        64.20r4   -17.540     d4   1.500 to 5.626 to 11.274r5*  18.400           d5     2.500 N3   1.84666                                    ν3                                        23.82r6*  16.017           d6     4.302r7   210.839           d7     4.900 N4   1.51680                                    ν4                                        64.20r8   -16.613           d8     2.200r9   ∞ (Aperture stop)           d9     11.848 to 7.722 to 2.074r10* -42.608           d10    2.700 N5   1.62060                                    ν5                                        38.26r11* -17.935           d11    2.302r12  -16.442           d12    1.500 N6   1.77250                                    ν6                                        49.77r13  -114.675           d13    3.700r14  -14.598           d14    1.800 N7   1.77250                                    ν7                                        49.77r15  -33.373______________________________________Aspherical Coefficients______________________________________r3:         ε = 0.10000 × 10       A4 = -0.55979 × 10.sup.-5       A6 = 0.59183 × 10.sup.-7       A8 = -0.12537 × 10.sup.-8       A10 = -0.20077 × 10.sup.-11       A12 = 0.92220 × 10.sup.-13r5:         ε = 0.10000 × 10       A4 = -0.98155 × 10.sup.-4       A6 = -0.10422 × 10.sup.-5       A8 = 0.10279 × 10.sup.-8       A10 = 0.65717 × 10.sup.-10       A12 = -0.15580 × 10.sup.-11r6:         ε = 0.10000 × 10       A4 = -0.88888 × 10.sup.-4       A6 = -0.17112 × 10.sup.-5       A8 = 0.23555 × 10.sup. -7       A10 = -0.21244 × 10.sup.-9       A12 = -0.16260 × 10.sup.-11       A14 = 0.65829 × 10.sup.-15       A15 = 0.10109 × 10.sup.-15       A16 = 0.58947 × 10.sup.-16r10:        ε = 0.10000 × 10       A3 = 0.90026 × 10.sup.-4       A4 = 0.56438 × 10.sup.-5       A5 = 0.23499 × 10.sup.-6       A6 = 0.17749 × 10.sup.-8       A7 = -0.11063 × 10.sup.-8       A8 = -0.18141 × 10.sup.-9       A10 = -0.20996 × 10.sup.-11       A12 = -0.16717 × 10.sup.-13r11:        ε = 0.10000 × 10       A3 = 0.53323 × 10.sup.-4       A4 = 0.34115 × 10.sup.-6       A5 = -0.20566 × 10.sup.-7       A6 = -0.45581 × 10.sup.-8       A7 = -0.42636 × 10.sup.-9       A8 = -0.23354 × 10.sup.-8       A9 = -0.38630 × 10.sup.-10       A10 = 0.71526 × 10.sup.-11       A12 = 0.27829 × 10.sup.-13______________________________________ 
    
     
                       TABLE 7______________________________________(7th Embodiment)______________________________________f = 39.1 to 55.0 to 116.4 FNO = 3.62 to 5.01 to 10.39Radius of Axial        Refractive AbbeCurvature Distance     Index      Number______________________________________r1   -17.326           d1     1.500 N1   1.83400                                    ν1                                        37.05r2   -32.356           d2     1.000r3   -84.420           d3     2.000 N2   1.51680                                    ν2                                        64.20r4   -18.390     d4   1.500 to 6.497 to 13.175r5*  19.799           d5     2.500 N3   1.84666                                    ν3                                        23.82r6*  17.489           d6     4.670r7   109.536           d7     4.900 N4   1.51728                                    ν4                                        69.43r8   -17.288           d8     2.200r9   ∞ (Aperture stop)     d9   13.749 to 8.752 to 2.074r10* -44.226           d10    2.500 N5   1.58340                                    ν5                                        30.23r11* -23.061           d11    3.960r12  -12.620           d12    1.000 N6   1.80100                                    ν6                                        46.54r13  -101.086______________________________________Aspherical Coefficients______________________________________r5:         ε = 0.10000 × 10       A4 = -0.96293 × 10.sup.-4       A6 = -0.10790 × 10.sup.-5       A8 = 0.66237 × 10.sup.-9       A10 = 0.62309 × 10.sup.-10       A12 = -0.15821 × 10.sup.-11r6:         ε = 0.10000 × 10       A4 = -0.85071 × 10.sup.-4       A6 = -0.17248 × 10.sup.-5       A8 = 0.23658 × 10.sup.-7       A10 = -0.21055 × 10.sup.-9       A12 = -0.16128 × 10.sup.-11       A14 = 0.65829 × 10.sup.-15       A16 = 0.58947 × 10.sup.-16r10:        ε = 0.10000 × 10       A3 = -0.48004 × 10.sup.-3       A4 = 0.24423 × 10.sup.-3       A5 = -0.41952 × 10.sup.-4       A6 = 0.44991 × 10.sup.-5       A7 = 0.78986 × 10.sup.-7       A8 = -0.44782 × 10.sup.-7       A9 = -0.42511 × 10.sup.-9       A10 = 0.33847 × 10.sup.-9       A11 = 0.79128 × 10.sup.-11       A12 = -0.20360 × 10.sup.-11       A13 = 0.60303 × 10.sup.-15       A14 = 0.64064 × 10.sup.-15       A15 = 0.10109 × 10.sup.-15       A16 = 0.11619 × 10.sup.-16r11:        ε = 0.10000 × 10       A3 = -0.44519 × 10.sup.-3       A4 = 0.13367 × 10.sup.-3       A5 = -0.11881 × 10.sup.-4       A6 = -0.25451 × 10.sup.-6       A7 = 0.40874 × 10.sup.-7       A8 = 0.42209 × 10.sup.-7       A9 = -0.68161 × 10.sup.-8       A10 =  0.11361 × 10.sup.-9       A11 = 0.30611 × 10.sup.-10       A12 = -0.14290 × 10.sup.-11       A13 = -0.15678 × 10.sup.-14______________________________________ 
    
     
                       TABLE 8______________________________________(8th Embodiment)______________________________________f = 39.3 to 55.0 to 102.1 FNO = 3.62 to 4.6 to 7.35Radius of Axial        Refractive AbbeCurvature Distance     Index      Number______________________________________r1*  -32.000           d1     1.500 N1   1.80741                                    ν1                                        31.59r2   -41.366           d2     0.500r3*  22.628           d3     2.000 N2   1.51728                                    ν2                                        69.43r4   126.263     d4   1.500 to 6.537 to 13.177r5*  19.795           d5     2.500 N3   1.84506                                    ν3                                        23.66r6*  14.388           d6     4.799r7   -503.890           d7     4.900 N4   1.52307                                    ν4                                        58.57r8   -13.707           d8     2.200r9   ∞ (Aperture stop)     d9   13.751 to 8.714 to 2.074r10* -20.339           d10    2.758 N5   1.58340                                    ν5                                        30.23r11* -21.454           d11    1.791r12  -15.248           d12    1.000 N6   1.61800                                    ν6                                        63.39r13  -797.932______________________________________Aspherical Coefficients______________________________________r1:         ε = 0.10000 × 10       A4 = 0.71231 × 10.sup.-7       A6 = 0.52195 × 10.sup.-7       A8 = -0.25359 × 10.sup.-9       A10 = -0.39813 × 10.sup.-12       A12 = 0.17476 × 10.sup.-14r3:         ε = 0.10000 × 10       A4 = 0.35042 × 10.sup.-5       A6 = 0.23103 × 10.sup.-7       A8 = -0.67780 × 10.sup.-9       A10 = -0.15550 × 10.sup.-11       A12 = 0.74233 × 10.sup.-13r5:         ε = 0.10000 × 10       A4 = -0.12239 × 10.sup.-3       A6 = -0.90107 × 10.sup.-6       A8 = 0.11554 × 10.sup.-8       A10 = 0.64400 × 10.sup.-10       A12 = -0.15674 × 10.sup.-11r6:         ε  = 0.10000 × 10       A4 = -0.10076 × 10.sup.-3       A6 = -0.14758 × 10.sup.-5       A8 = 0.24553 × 10.sup.-7       A10 = -0.20994 × 10.sup.-9       A12 = -0.16222 × 10.sup.-11       A14 = 0.65829 × 10.sup.-15       A15 = 0.58947 × 10.sup.-16r10:        ε = 0.10000 × 10       A3 = -0.42559 × 10.sup.-3       A4 = 0.24016 × 10.sup.-3       A5 = -0.41374 × 10.sup.-4       A6 = 0.44519 × 10.sup.-5       A7 = 0.73797 × 10.sup.-7       A8 = -0.44807 × 10.sup.-7       A9 = -0.42511 × 10.sup.-9       A10 = 0.34232 × 10.sup.-9       A11 = 0.79128 × 10.sup.-11       A12 = -0.19916 × 10.sup.-11       A13 = 0.60303 ×  10.sup.-15       A14 = 0.64064 × 10.sup.-15       A15 = 0.10109 × 10.sup.-15       A16 = 0.11619 × 10.sup.-16r11:        ε = 0.10000 × 10       A3 = -0.40645 × 10.sup.-3       A4 = 0.13873 × 10.sup.-3       A5 = -0.12074 × 10.sup.-4       A6 = -0.24438 × 10.sup.-6       A7 = 0.39639 × 10.sup.-7       A8 = 0.40410 × 10.sup.-7       A9 = -0.66676 × 10.sup.-8       A10 = 0.11883 × 10.sup.-9       A11 = 0.30611 × 10.sup.-10       A12 = -0.13772 × 10.sup.-11       A13 = -0.15678 × 10.sup.-14______________________________________ 
    
     
                       TABLE 9______________________________________             ##STR1##                  ##STR2##______________________________________1st embodiment     2.60   2.762nd embodiment     3.20   3.463rd embodiment     3.93   4.774th embodiment     10.2   10.35th embodiment     3.41   4.266th embodiment     3.65   4.087th embodiment     8.53   10.038th embodiment     1.82   1.88______________________________________ 
    
     
                       TABLE 10______________________________________            ##STR3##                 ##STR4##______________________________________1st embodiment    0.240  7.582nd embodiment    0.139  3.553rd embodiment    0.150  5.594th embodiment    0.085  9.525th embodiment    0.147  4.146th embodiment    0.113  3.067th embodiment    0.052  3.308th embodiment    0.448  7.81______________________________________ 
    
     
                       TABLE 11______________________________________            ##STR5##                   ##STR6##______________________________________1st embodiment    273      0.0392nd embodiment    384      0.0363rd embodiment    531      0.0334th embodiment    1071     0.0155th embodiment    409      0.0346th embodiment    438      0.0317th embodiment    1022     0.0148th embodiment    191      0.056______________________________________