Abstract:
A zoom lens system capable of correcting a secondary spectrum is disclosed. The zoom lens system includes a first lens unit with a positive optical power, a second lens unit with a negative optical power, an aperture stop, and a rear lens component including at least one lens unit in an order from an object side to an image side. In the zoom lens system, during zooming from a wide angle end to a telephoto end, an interval between the first lens unit and the second lens unit increases, and an interval between the second lens unit and the aperture stop decreases. Then, a material satisfying the following conditions: 
 
νd1n&lt;35 
 
θ gF 1 n &lt;−0.0027ν d 1 n +0.680 
 
is used for the negative lens in the first lens unit. Herein, νd 1 n represents an Abbe number, and θgF 1 n represents a partial dispersion ratio.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a zoom lens system, which is preferably used as an image taking optical system for a silver film camera, a digital still camera, a video camera and the like.  
         [0003]     2. Related Background Art  
         [0004]     Along with the enhancement in resolution of a digital still camera, i.e., an increase of the number of pixels in the digital still camera, there is a demand for correcting a monochromatic aberration and sufficiently correcting a chromatic aberration in a zoom lens as an image taking optical system for a solid-state image pickup element with a high resolution. In particular, when the focal length at a telephoto end of a zoom lens increases as a result of an increase in a zoom ratio or an imaging magnification, there is a demand for the reduction in a secondary spectrum, as well as the primary achromatism, regarding a chromatic aberration.  
         [0005]     Conventionally, in order to correct a secondary spectrum of an axial chromatic aberration (longitudinal chromatic aberration) at a telephoto end, a number of zoom lenses using anomalous dispersion (extraordinary dispersion) glass have been known. Furthermore, as a zoom lens configuration suitable for a high zoom ratio, there is a positive lead type in which a lens unit closest to an object side has a positive refractive power.  
         [0006]     For example, JP H06-43363 A and JP H03-58490 B (counterpart: U.S. Pat. No. 4,709,997) disclose an example using glass having anomalous dispersibility for a zoom lens in which three lens units having positive, negative, and positive refractive powers are arranged in this order from the object side.  
         [0007]     For example, JP 3097399 B, JP 2002-62748 A (counterpart: U.S. Pat. No. 6,594,087), JP H08-248317 A, and JP 2001-194590 A (counterpart: U.S. Pat. No. 6,404,561) disclose an example using glass having anomalous dispersibility for a zoom lens in which four lens units having positive, negative, positive, and positive refractive powers are arranged in this order from the object side.  
         [0008]     For example, JP 2001-350093 A (counterpart: U.S. Pat. No. 6,449,433) discloses an example using glass having anomalous dispersibility for a zoom lens in which five lens units having positive, negative, positive, negative, and positive refractive powers are arranged in this order from the object side.  
         [0009]     Any of the above-mentioned conventional examples use glass having an Abbe number exceeding 80 for a positive lens in a first lens unit having a positive refractive power. In general, low dispersion glass having an Abbe number exceeding 80 has anomalous dispersibility. The use of such glass for a positive lens in a first lens unit of a positive lead type is effective for reducing a secondary spectrum at a telephoto end.  
         [0010]     However, the above-mentioned documents disclose no example using a material having anomalous dispersibility for a negative lens in the first lens unit, which are focused on only the reduction in a secondary spectrum by use of the anomalous dispersion characteristics of a positive lens. In order to further reduce a secondary spectrum amount with such a configuration, it is considered to use a material having high anomalous dispersibility such as fluorite or to increase the number of positive lenses in the first lens unit. The former has a problem in terms of cost, and the latter has a problem in terms of enlargement.  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention has been made in view of the above-mentioned conventional examples, and has an object to realize a zoom lens system in which a secondary spectrum is corrected satisfactorily without increasing a cost.  
         [0012]     An illustrative zoom lens system of the present invention includes a first lens unit having a positive refractive power (optical power=inverse of focal length), a second lens unit having a negative refractive power, an aperture stop, and a rear lens component including at least one lens unit in this order from an object side to an image side, with an interval between the first lens unit and the second lens unit increasing and an interval between the second lens unit and the aperture stop decreasing during zooming from a wide angle end to a telephoto end, in which the following conditional formulas are satisfied: 
 
νd1n&lt;35 
 
θ gF 1 n &lt;−0.0027ν d 1 n+ 0.680 
 
 where an Abbe number of a material constituting at least one negative lens forming the first lens unit is νd1n, and a partial dispersion ratio is θgF1n.
 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a cross-sectional view of a zoom lens according to Embodiment 1 of the present invention;  
         [0014]      FIGS. 2A, 2B  and  2 C show various aberrations of the zoom lens according to Embodiment 1 of the present invention;  
         [0015]      FIG. 3  is a cross-sectional view of a zoom lens according to Embodiment 2 of the present invention;  
         [0016]      FIGS. 4A, 4B  and  4 C show various aberrations of the zoom lens according to Embodiment 2 of the present invention;  
         [0017]      FIG. 5  is a cross-sectional view of a zoom lens according to Embodiment 3 of the present invention;  
         [0018]      FIGS. 6A, 6B  and  6 C shows various aberrations of the zoom lens according to Embodiment 3 of the present invention;  
         [0019]      FIG. 7  is a cross-sectional view of a zoom lens according to Embodiment 4 of the present invention;  
         [0020]      FIGS. 8A, 8B  and  8 C show various aberrations of the zoom lens according to Embodiment 4 of the present invention;  
         [0021]      FIG. 9  is a cross-sectional view of a zoom lens according to Embodiment 5 of the present invention;  
         [0022]      FIGS. 10A, 10B  and  10 C show various aberrations of the zoom lens according to Embodiment 5 of the present invention;  
         [0023]      FIG. 11  is a cross-sectional view of a zoom lens according to Embodiment 6 of the present invention;  
         [0024]      FIG. 12A, 12B  and  12 C show various aberrations of the zoom lens according to Embodiment 6 of the present invention;  
         [0025]      FIG. 13  is a graph showing a relationship between an Abbe number νd and a partial dispersion ratio θgF;  
         [0026]      FIG. 14  is a schematic view showing main portions of a video camera; and  
         [0027]      FIG. 15  is a schematic view showing main portions of a digital still camera. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]     Hereinafter, a zoom lens system of the present invention will be described by way of an example with reference to the drawings. The zoom lens disclosed in the present example is an image taking optical system for an image pickup apparatus such as a digital still camera and a video camera for forming an object image on a solid-state image pickup element (photoelectric conversion element) such as a CCD sensor and a CMOS sensor.  
         [0029]      FIGS. 1, 3 ,  5 ,  7 ,  9 , and  11  are cross-sectional views at a wide angle end of the zoom lenses of Embodiments 1 to 6.  FIGS. 2A-2C ,  4 A- 4 C,  6 A- 6 C,  8 A- 8 C,  10 A- 10 C, and  12 A- 12 C respectively show aberrations of the zoom lenses of Embodiments 1 to 6.  FIGS. 2A, 4A ,  6 A,  8 A,  10 A, and  12 A respectively show a state of a wide angle end.  FIGS. 2B, 4B ,  6 B,  8 B,  10 B, and  12 B respectively show a state at an intermediate focal position.  FIGS. 2C, 4C ,  6 C,  8 C,  10 C, and  12 C respectively show a state at a telephoto end.  
         [0030]     In each lens cross-section, the left side corresponds to an object side (front side), and the right side corresponds to an image side (rear side). L 1  denotes a first lens unit having a negative refractive power (optical power=inverse of focal length). L 2  denotes a second lens unit having a positive refractive power. L 3  denotes a third lens unit having a positive power. L 4  denotes a fourth lens unit having a positive refractive power in Embodiments 1 to 4, and a negative refractive power in Embodiments 5 and 6. L 5  denotes a fifth lens unit having a positive refractive power in Embodiments 5 and 6. SP denotes an aperture stop, and FC denotes a flare-cut stop. G denotes a glass block provided in terms of design so as to correspond to a parallel plate present in an optical path such as an optical low-pass filter, an infrared-cut filter, or a cover glass. IP denotes an image plane on which a photosensitive surface of a solid-state image pickup element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor is positioned.  
         [0031]     The zoom lens in each embodiment includes a first lens unit L 1  having a positive refractive power, a second lens unit L 2  having a negative refractive power, an aperture stop, and a rear lens component including at least one lens unit in an order from the object side to the image side. The rear end component is composed of a third lens unit L 3  and a fourth lens unit L 4  in Embodiments 1 to 4, and is composed of a third lens unit L 3  to a fifth lens unit L 5  in Embodiments 5 and 6. In any embodiment, during zooming from a wide angle end to a telephoto end, the interval between the first lens unit L 1  and the second lens unit L 2  becomes large, and the interval between the second lens unit L 2  and the aperture stop SP becomes small.  
         [0032]     In the zoom lenses of Embodiments 1 to 3 shown in  FIGS. 1, 3 , and  5 , during zooming from a wide angle end to a telephoto end, the first lens unit L 1  moves to the object side so that the interval between the first lens unit L 1  and the second lens unit L 2  becomes large. The second lens unit L 2  moves to the image side so that the interval between the second lens unit L 2  and the aperture stop SP becomes small. The third lens unit L 3  moves to the object along the locus convex to the object side so that the interval between the second lens unit L 2  and the third lens unit L 3  becomes small. Thus, main change in magnification is performed. The variation in the image plane involved in magnification is compensated by moving the fourth lens unit L 4  along the locus convex to the object side.  
         [0033]     Thus, in the zoom lenses of Embodiments 1 to 3, the first lens unit L 1  moves during zooming, whereby the total length of the entire lens system at the wide angle end is shortened to realize miniaturization in the optical axis direction. Furthermore, the interval between the first lens unit L 1  and the aperture stop SP is shortened at the wide angle end, whereby the effective diameter of the first lens unit L 1  is suppressed from increasing to reduce the diameter of a front lens. Furthermore, during zooming from the wide angle end to the telephoto end, the third lens unit L 3  moves to the object side, and the moved locus of the third lens unit L 3  is set to enlarge the interval between the third lens unit L 3  and the fourth lens unit L 4 , whereby the third lens unit L 3  is partially allowed to change magnification. Because of this, the function of changing magnification by changing the interval between the first lens unit L 1  and the second lens unit L 2  is weakened, so that the interval between the first lens unit L 1  and the second lens unit L 2  at the telephoto end can be shortened. Consequently, there is a merit that the total length of the entire system at the telephoto end is shortened and the diameter of a front lens is reduced.  
         [0034]     In Embodiments 1 to 3, the aperture stop SP moves integrally with the third lens unit L 3  during zooming but may move separately. When they move integrally, the number of moving units can be reduced, which is likely to simplify the mechanical structure. On the other hand, in the case where the aperture stop SP by moving separately from the third lens unit L 3 , it is advantageous for reducing the diameter of a front lens by moving the aperture stop SP, in particular, along the locus convex to the object side.  
         [0035]     Embodiment 4 shown in  FIG. 7  is the same as Embodiments 1 to 3 in the configuration of four lens units (positive, negative, positive, and positive), except a movement path of each lens unit during zooming. In Embodiment 4, during zooming from the wide angle end to the telephoto end, the distance by which the first lens unit L 1  moves to the object side is long compared with Embodiments 1 to 3, and the second lens unit L 2  substantially reciprocates on an optical axis while drawing a locus convex to the image side. Furthermore, during zooming from the wide angle end to the telephoto end, the third lens unit L 3  moves monotonously to the object side.  
         [0036]     Embodiment 5 shown in  FIG. 9  is directed to the configuration of five lens units (positive, negative, positive, negative, and positive). During zooming from the wide angle end to the telephoto end, the first lens unit L 1  moves to the object side, the second lens unit L 2  moves to the image side, the third lens unit L 3  moves to the object side, the fourth lens unit L 4  moves to the image side, and the fifth lens unit L 5  moves to the object side. The zoom lens of Embodiment 5 is designed as an image taking optical system for a camera in which a solid-state image pickup element is prepared for each color of RGB (Red, Green, Blue). Thus, a color separation prism is placed at the back of the fifth lens unit L 5 , so that the glass block G is thicker than that of the other embodiments, as including an equivalent optical length of the color separation prism.  
         [0037]     Embodiment 6 shown in  FIG. 11  is the same as Embodiment 5 in the configuration of five lens units (positive, negative, positive, negative, and positive) except that the first lens unit L 1  and the third lens unit L 3  do not move during zooming.  
         [0038]     The present invention is not limited to the movement system of the above-mentioned embodiments, and also includes a configuration in which the first lens unit and the third lens unit are fixed during zooming in the zoom lens of four units (positive, negative, positive, and positive).  
         [0039]     Next, the configuration of the first lens unit L 1  that is most characteristic in the present invention will be described.  
         [0040]     In the zoom lens system of the present invention, a secondary spectrum on the telephoto side occurring in the first lens unit L 1  is reduced by using a material having high dispersibility and anomalous dispersibility for a negative lens in the first lens unit L 1 . That is, the first lens unit of each embodiment includes at least one negative lens, and the negative lens is made of a material satisfying the following conditional formulas: 
 
νd1n&lt;35   (1) 
 
θ gF 1 n &lt;−0.0027ν d 1 n+ 0.680   (2) 
 
 where νd1n represents an Abbe number of at least one negative lens in the first lens unit, and θgF1n represents a partial dispersion ratio of the negative lens. The Abbe number and the partial dispersion ratio θgF1n are defined by the following expressions: 
 
ν d =( Nd− 1)/( NF−NC ) 
 
θ gF =( Ng−NF )/( NF−NC ) 
 
 where NC, Nd, NF, and Ng represent refractive indexes at a C-line, a d-line, an F-line, and a g-line. 
 
         [0041]     According to the present invention, the primary achromatism and the correction of a secondary spectrum are both performed by allowing the first lens unit L 1  to have a negative lens composed of a material satisfying the conditional formulas (1) and (2) simultaneously.  
         [0042]     In each embodiment, the first lens unit L 1  is composed of three lenses (negative lens, positive lens, and positive lens) in an order from the object side to the image side, and the negative lens closest to the object side and the second positive lens are set to be cemented lenses. By adopting a material satisfying the conditional formulas (1) and (2) for the negative lens closest to the object side, each achromatism of an axial chromatic aberration and a chromatic aberration of magnification and the correction of a spherical aberration are both performed while keeping a high zoom ratio and using a minimum required number of lens units. As the material satisfying the conditional formulas (1) and (2), S-LAH79 (Nd=2.00330, νd=28.3, θgF=0.598) produced by OHARA Inc. was used.  
         [0043]      FIG. 13  is a graph showing a relationship between an Abbe number νd and a partial dispersion ratio θgF. In  FIG. 13 , A represents PBM2 (νd=36.26, θgF=0.5828) in OHARA Inc.; B represents NSL7 (νd=60.49, θgF=0.5436) in OHARA Inc.; C represents S-TIH53 (νd=23.8, θgF=0.621) in OHARA Inc.; and D represents S-TIM22 (νd=33.8, θgF=0.594) in OHARA Inc. When a line connecting A to B is a reference line  1 , regarding the distribution of optical glass, high dispersion glass with νd smaller than about 35 is likely to be on an upper side of the reference line  1 , low dispersion glass with νd of about 35 to 65 is likely to be on a lower side of the reference line  1 , and anomalous dispersion glass with νd of 60 or more is positioned on an upper side of the reference line  1 . However, in high dispersion glass with an Abbe number of smaller than 35, none of the glass is positioned on the lower side of the reference line  1  connecting A to B. When a line connecting C to D is a reference line  2  in high dispersion glass in  FIG. 13 , glass is positioned mostly in the vicinity of the reference line  2  at νd of 35 or less, and some glass is positioned on the lower side of the reference line  2 . In particular, S-LAH79 is positioned on a lower side of the reference line  2 , and hence has anomalous dispersibility as a high dispersion material. When a material having a small partial dispersion ratio in spite of high dispersion is used for the negative lens in the first lens unit L 1 , a secondary spectrum on the telephoto side can be reduced.  
         [0044]     If the negative lens using anomalous dispersion glass is allowed to have a refracting power to some degree in the configuration of the first lens unit L 1 , even if the positive lens in the first lens unit L 1  is not made of anomalous dispersion glass, a secondary spectrum can be reduced in a similar manner to that in the conventional configuration using anomalous dispersion glass only for the positive lens in the first lens unit L 1 . In this case, the positive lens in the first lens unit L 1  may not be made of anomalous dispersion glass having a low refracting power. Therefore, the curvature can be small with respect to a desired refracting power (radius of curvature can be large) to make the positive lens thin, which leads to the miniaturization of the first lens unit L 1 .  
         [0045]     Furthermore, when low dispersion glass (positioned on an upper side of the reference line  1  at νd of 60 or more in  FIG. 13 ) having anomalous dispersion characteristics is used for the conventional positive lens in the first lens unit L 1  as in the conventional example, it is needless to say that a secondary spectrum can be reduced further. Thus, by using glass having anomalous dispersibility for both the negative lens and the positive lens, the ability to correct a secondary spectrum can be enhanced compared with the conventional example. Consequently, the request performance of a secondary spectrum can be enhanced in accordance with an image pickup element with high resolution, and the focal length at the telephoto end is increased to enhance a zoom ratio.  
         [0046]     The negative lens and the positive lens constituting the cemented lenses in the first lens unit L 1  of Embodiment 2 are made of S-LAH79 and S-FPL51 produced by OHARA Inc. which are materials having anomalous dispersibility, whereby the correction force of a secondary spectrum is increased. The negative lens and the positive lens constituting the cemented lenses in the first lens unit L 1  of Embodiment 3 are made of NBFD15 produced by HOYA Co. Ltd. and S-FPL51 produced by OHARA Inc. The negative lens and the positive lens constituting the cemented lenses in the first lens unit L 1  of Embodiment 4 are made of S-LAH79 and S-LAL14 produced by OHARA Inc. The negative lens and the positive lens constituting the cemented lenses in the first lens unit L 1  of Embodiment 5 are made of S-LAH79 and S-FSL5 produced by OHARA Inc. The negative lens and the positive lens constituting the cemented lenses in the first lens unit L 1  of Embodiment 6 are made of S-LAH79 and S-FPL51 produced by OHARA Inc.  
         [0047]     Herein, the technical meaning of the above-mentioned conditional formulas (1) and (2) will be described.  
         [0048]     The conditional formula (1) defines an Abbe number of the negative lens in the first lens unit. When an Abbe number increases exceeding the upper limit of the conditional formula (1), dispersion becomes too small, which makes it difficult to correct a primary chromatic aberration occurring in the positive lens in the first lens unit L 1 . In order to perform primary achromatism without increasing the refracting power of the negative lens in the first lens unit L 1  to an extreme extent, it is preferable to use a high dispersion material having an Abbe number in the range of the conditional formula (1).  
         [0049]     The conditional formula (2) defines a partial dispersion ratio of the negative lens in the first lens unit L 1 . In  FIG. 13 , a line segment E satisfies θgF1n=−0.0027νd1n+0.68. The conditional formula (2) means to be positioned on a lower side of the line segment E in  FIG. 13 . The line segment E has the same slope as that of the reference line  2 , and the material satisfying the conditional formula (2) has anomalous dispersibility to some degree with respect to the material in the vicinity of the reference line  2 . A material having a partial dispersion ratio outside the range of the conditional formula (2) does not have anomalous dispersibility required for reducing a secondary spectrum.  
         [0050]     Next, other conditions which the zoom lens of each Embodiment satisfies will be described.  
         [0051]     When the focal length of the negative lens composed of a material satisfying the conditional formulas (1) and (2) in the first lens unit L 1  is F1n, the focal length of the first lens unit L 1  is f1, the focal length at the telephoto end of the entire system is ft, the focal length of the second lens unit L 2  is f2, the focal length at the wide angle end of the entire system is fw, the Abbe number of the positive lens whose Abbe number is largest in the first lens unit L 1  is νd1p, and the partial dispersion ratio is θgF1p, the following conditional formulas are satisfied. 
 
1.0 &lt;|f 1 n|/f 1&lt;3.0   (3) 
 
0.5 &lt;f 1 /ft&lt; 2.5   (4) 
 
0.3 &lt;|f 2|/( fw×ft )−½&lt;0.8   (5) 
 
−0.0024&lt;(θ gF 1 n−θgF 1 p )/(ν d 1 n−νd 1 p )   (6) 
 
         [0052]     The conditional formula (3) defines the focal length of the negative lens having high dispersion and anomalous dispersibility of the first lens unit L 1 . When the focal length of the negative lens having high dispersion and anomalous dispersibility becomes too long exceeding the upper limit, i.e., the refracting power of the negative lens becomes too weak, even when a high dispersion material is used, the primary chromatic aberration in the first lens unit L 1  cannot be corrected sufficiently. When the focal length of the negative lens becomes too short exceeding the lower limit, i.e., the refracting power of the negative lens becomes too strong, a Petzval sum becomes large on the negative side, which may cause the distortion of an image surface.  
         [0053]     The conditional formula (4) defines the focal length of the first lens unit L 1 . When the focal length of the first lens unit L 1  becomes too long exceeding the upper limit, i.e., the refracting power of the first lens unit L 1  becomes too weak, the total length of the entire system at the telephoto end becomes long, which is disadvantageous in terms of miniaturization. When the focal length of the first lens unit L 1  becomes too short exceeding the lower limit, i.e., the refracting power of the first lens unit L 1  becomes too strong, the occurrence of a spherical aberration becomes remarkable at the telephoto end.  
         [0054]     The conditional formula (5) defines the focal length of the second lens unit L 2 . When the focal length of the second lens unit L 2  becomes too long exceeding the upper limit, i.e., the refracting power of the second lens unit L 2  becomes too weak, the moving amount of the second lens unit L 2  for keeping a desired zoom ratio becomes large to enlarge the full length of the entire system at the wide angle end, which is disadvantageous in terms of miniaturization. When the focal length of the second lens unit L 2  becomes too short exceeding the lower limit, i.e., the refracting power of the second lens unit L 2  becomes too strong, a Petzval sum becomes large on the negative side, which may cause the distortion of an image surface.  
         [0055]     The conditional formula (6) defines the relationship of a partial dispersion ratio of the negative lens and the positive lens in the first lens unit L 1 . In the conditional formula (6), (θgF1n−θgF1p)/(νd1n−νd1p) represents a slope of a line segment connecting the corresponding points based on the Abbe number and the partial dispersion ratio of the negative lens and the positive lens in the first lens unit L 1  in  FIG. 13 . As the slope is smaller, a secondary spectrum is reduced more. When the slope becomes too large exceeding the lower limit, even if the material satisfying the conditional formulas (1) and (2) is used for the negative lens, it is difficult to reduce a secondary spectrum. Thus, it is preferable that the positive lens satisfies the conditional formula (6) under the condition that the negative lens satisfies the conditional formulas (1) and (2).  
         [0056]     Furthermore, it is preferable that the negative lens composed of a material satisfying the conditional formulas (1) and (2) of the first lens unit satisfies the following conditional formula: 
 
1.80&lt;N1n   (7) 
 
 where N1n is a refractive index of the negative lens. 
 
         [0057]     The conditional formula (7) defines the refractive index of the negative lens of the first lens unit L 1 . In the case where the refracting power of the negative lens in the first lens unit L 1  satisfies the conditional formula (3), when the refractive index becomes too small exceeding the lower limit of the conditional formula (7), a Petzval sum becomes large on the negative side, which may cause the distortion of an image surface.  
         [0058]     Furthermore, among the above-mentioned conditional formulas, the conditional formulas (2) and (7) are preferably set to be in the following ranges. 
 
θ gF 1 n &lt;−0.0027ν d 1 n+ 0.676   (2a) 
 
1.85&lt;N1n   (7a) 
 
         [0059]     The conditional formula (2a) is obtained by changing a constant term of the conditional formula (2), and further away from the reference line  2  in  FIG. 13 . The negative lens in the first lens unit L 1  is limited to a material having higher anomalous dispersibility for satisfying such a condition, so that the effect of reducing a secondary spectrum is enhanced.  
         [0060]     The conditional formula (7a) is obtained by further limiting the conditional formula (7) to a high refractive index side, which further reduces the distortion of an image surface to provide flat image surface characteristics.  
         [0061]     Next, numerical data of Numerical Embodiments 1 to 6 corresponding to Embodiments 1 to 6 will be shown. In the numerical embodiments, f denotes a focal length, Fno denotes an F-number, ω denotes a half angle of view, i denotes an order counted from the object side, Ri denotes a radius of curvature of the i-th plane, Di denotes an axial interval between the i-th surface and the (i+1)th surface and Ni, νi, θgFi denote a refractive index, an Abbe number, and a partial dispersion ratio based on a d-line of the i-th material, respectively. Regarding θgFi, only a lens forming the first lens unit will be shown.  
         [0062]     When the traveling direction of light is positive, x represents a displacement amount from a surface apex in an optical axis direction, h represents a height from an optical axis in a direction vertical to an optical axis, R represents a paraxial radius of curvature, k represents a conic constant, and B to E and A′ to D′ represent aspherical coefficients, respectively, the aspherical shape is represented by the following formula:  
       x   =           (     1   /   R     )     ⁢     h   2         1   +       {     1   -       (     1   +   k     )     ⁢       (     h   /   R     )     2         }           +     Bh   4     +     Ch   6     +     Dh   8     +     Eh   10     +       A   ′     ⁢     h   3       +       B   ′     ⁢     h   5       +       C   ′     ⁢     h   7       +       D   ′     ⁢     h   9             
 
         [0063]     Table 1 shows the relationship between the above-mentioned respective conditional formulas and the numerical embodiments.  
                                                                                                         (Numerical Embodiment 1)                   f = 6.74 to 64.80 Fno = 2.88 to 3.80 2ω = 52.9° to 5.9°                    R1 = 45.818   D1 = 1.30   N1 = 2.003300   ν1 = 28.3       R2 = 26.799   D2 = 4.30   N2 = 1.487490   ν2 = 70.2       R3 = 165.297   D3 = 0.20       R4 = 27.523   D4 = 3.70   N3 = 1.696797   ν3 = 55.5       R5 = 144.903   D5 = Variable       R6 = 40.613   D6 = 0.80   N4 = 1.834000   ν4 = 37.2       R7 = 7.384   D7 = 3.68       R8 = −30.183   D8 = 0.70   N5 = 1.772499   ν5 = 49.6       R9 = 23.730   D9 = 0.86       R10 = 15.820   D10 = 1.90   N6 = 1.922860   ν6 = 18.9       R11 = 69.378   D11 = Variable       R12 = Stop   D12 = 1.04       R13 = 9.532   D13 = 3.00   N7 = 1.583126   ν7 = 59.4       R14 = 284.452   D14 = 2.60       R15 = 15.350   D15 = 0.70   N8 = 1.846660   ν8 = 23.9       R16 = 8.422   D16 = 1.10       R17 = 48.546   D17 = 1.60   N9 = 1.487490   ν9 = 70.2       R18 = −39.980   D18 = 2.30       R19 = Flare-cut   D19 = Variable       R20 = 17.765   D20 = 2.70   N10 = 1.696797   ν10 = 55.5       R21 = −28.648   D21 = 0.70   N11 = 1.846660   ν11 = 23.9       R22 = −887.256   D22 = Variable       R23 = ∞   D23 = 2.60   N12 = 1.516330   ν12 = 64.1       R24 = ∞                        Focal Length                Variable Interval   6.74   26.63   64.80                       D5   0.92   17.65   26.63           D11   27.64   8.41   1.93           D19   1.45   0.27   6.14           D22   5.00   10.27   3.75                        Aspherical Coefficients       Thirteenth Surface                        k = 9.08580e−02                   B = −1.25669e−05   C = 2.05092e−05   D = 2.02174e−07           E = −3.51672e−10           A′ = −6.80016e−05   B′ = −6.92855e−05   C′ = −3.27871E−06           D′ = 0           θgF1 = 0.598   θgF2 = 0.530   θgF3 = 0.543                      
 
         [0064]    
       
         
               
             
               
               
               
               
             
               
               
             
               
               
               
               
               
             
               
             
               
               
               
               
             
           
               
                   
               
               
                   
               
               
                 (Numerical Embodiment 2) 
               
               
                   
               
             
             
               
                 f = 6.74 to 64.80 Fno = 2.88 to 3.80 2ω = 52.9° to 5.9° 
               
               
                   
               
             
          
           
               
                 R1 = 45.907 
                 D1 = 1.40 
                 N1 = 2.003300 
                 ν1 = 28.3 
               
               
                 R2 = 27.592 
                 D2 = 5.00 
                 N2 = 1.496999 
                 ν2 = 81.5 
               
               
                 R3 = 60726.963 
                 D3 = 0.20 
               
               
                 R4 = 27.979 
                 D4 = 3.90 
                 N3 = 1.696797 
                 ν3 = 55.5 
               
               
                 R5 = 147.199 
                 D5 = Variable 
               
               
                 R6 = 69.486 
                 D6 = 0.80 
                 N4 = 1.834000 
                 ν4 = 37.2 
               
               
                 R7 = 7.835 
                 D7 = 3.38 
               
               
                 R8 = −30.481 
                 D8 = 0.70 
                 N5 = 1.772499 
                 ν5 = 49.6 
               
               
                 R9 = 24.130 
                 D9 = 0.86 
               
               
                 R10 = 16.616 
                 D10 = 1.90 
                 N6 = 1.922860 
                 ν6 = 18.9 
               
               
                 R11 = 93.556 
                 D11 = Variable 
               
               
                 R12 = Stop 
                 D12 = 1.04 
               
               
                 R13 = 9.526 
                 D13 = 3.00 
                 N7 = 1.583126 
                 ν7 = 59.4 
               
               
                 R14 = 329.095 
                 D14 = 2.60 
               
               
                 R15 = 15.349 
                 D15 = 0.70 
                 N8 = 1.846660 
                 ν8 = 23.9 
               
               
                 R16 = 8.420 
                 D16 = 1.10 
               
               
                 R17 = 42.813 
                 D17 = 1.60 
                 N9 = 1.487490 
                 ν9 = 70.2 
               
               
                 R18 = −37.289 
                 D18 = 2.30 
               
               
                 R19 = Flare-cut 
                 D19 = Variable 
               
               
                 R20 = 15.846 
                 D20 = 2.70 
                 N10 = 1.696797 
                 ν10 = 55.5 
               
               
                 R21 = −32.767 
                 D21 = 0.70 
                 N11 = 1.846660 
                 ν11 = 23.9 
               
               
                 R22 = 128.024 
                 D22 = Variable 
               
               
                 R23 = ∞ 
                 D23 = 2.60 
                 N12 = 1.516330 
                 ν12 = 64.1 
               
               
                 R24 = ∞ 
               
               
                   
               
             
          
           
               
                   
                 Focal Length 
               
             
          
           
               
                   
                 Variable Interval 
                 6.74 
                 25.05 
                 64.80 
               
               
                   
                   
               
               
                   
                 D5 
                 0.92 
                 16.76 
                 25.32 
               
               
                   
                 D11 
                 28.66 
                 10.32 
                 4.26 
               
               
                   
                 D19 
                 3.03 
                 2.94 
                 9.91 
               
               
                   
                 D22 
                 5.00 
                 9.18 
                 1.56 
               
               
                   
                   
               
             
          
           
               
                 Aspherical Coefficients 
               
               
                 Thirteenth Surface 
               
               
                   
               
             
          
           
               
                   
                 k = 7.37802e−02 
                   
                   
               
               
                   
                 B = −2.21673e−06 
                 C = 1.96441e−05 
                 D = 2.46908e−07 
               
               
                   
                 E = −8.17943e−10 
               
               
                   
                 A′ = −8.95231e−05 
                 B′ = −6.71741e−05 
                 C′ = −3.38043E−06 
               
               
                   
                 D′ = 0 
               
               
                   
                 θgF1 = 0.598 
                 θgF2 = 0.538 
                 θgF3 = 0.543 
               
               
                   
                   
               
             
          
         
       
     
         [0065]    
       
         
               
             
               
               
               
               
             
               
               
             
               
               
               
               
               
             
               
             
               
               
               
               
             
           
               
                   
               
               
                   
               
               
                 (Numerical Embodiment 3) 
               
               
                   
               
             
             
               
                 f = 6.73 to 64.88 Fno = 2.88 to 3.80 2ω = 52.9° to 5.9° 
               
               
                   
               
             
          
           
               
                 R1 = 62.074 
                 D1 = 1.40 
                 N1 = 1.806100 
                 ν1 = 33.3 
               
               
                 R2 = 26.099 
                 D2 = 5.00 
                 N2 = 1.496999 
                 ν2 = 81.5 
               
               
                 R3 = 8344.037 
                 D3 = 0.20 
               
               
                 R4 = 28.137 
                 D4 = 3.90 
                 N3 = 1.696797 
                 ν3 = 55.5 
               
               
                 R5 = 166.588 
                 D5 = Variable 
               
               
                 R6 = 54.369 
                 D6 = 0.80 
                 N4 = 1.834000 
                 ν4 = 37.2 
               
               
                 R7 = 7.774 
                 D7 = 3.42 
               
               
                 R8 = −31.133 
                 D8 = 0.70 
                 N5 = 1.772499 
                 ν5 = 49.6 
               
               
                 R9 = 27.337 
                 D9 = 0.86 
               
               
                 R10 = 16.657 
                 D10 = 1.90 
                 N6 = 1.922860 
                 ν6 = 18.9 
               
               
                 R11 = 78.428 
                 D11 = Variable 
               
               
                 R12 = Stop 
                 D12 = 1.04 
               
               
                 R13 = 9.807 
                 D13 = 3.00 
                 N7 = 1.583126 
                 ν7 = 59.4 
               
               
                 R14 = 104.757 
                 D14 = 2.60 
               
               
                 R15 = 13.373 
                 D15 = 0.70 
                 N8 = 1.846660 
                 ν8 = 23.9 
               
               
                 R16 = 8.401 
                 D16 = 1.10 
               
               
                 R17 = 75.057 
                 D17 = 1.60 
                 N9 = 1.487490 
                 ν9 = 70.2 
               
               
                 R18 = −39.378 
                 D18 = 2.30 
               
               
                 R19 = Flare-cut 
                 D19 = Variable 
               
               
                 R20 = 17.525 
                 D20 = 2.70 
                 N10 = 1.696797 
                 ν10 = 55.5 
               
               
                 R21 = −23.817 
                 D21 = 0.70 
                 N11 = 1.846660 
                 ν11 = 23.9 
               
               
                 R22 = −1527.617 
                 D22 = Variable 
               
               
                 R23 = ∞ 
                 D23 = 2.60 
                 N12 = 1.516330 
                 ν12 = 64.1 
               
               
                 R24 = ∞ 
               
               
                   
               
             
          
           
               
                   
                 Focal Length 
               
             
          
           
               
                   
                 Variable Interval 
                 6.73 
                 26.76 
                 64.88 
               
               
                   
                   
               
               
                   
                 D5 
                 0.92 
                 18.84 
                 28.38 
               
               
                   
                 D11 
                 29.34 
                 8.92 
                 1.88 
               
               
                   
                 D19 
                 1.93 
                 0.61 
                 5.91 
               
               
                   
                 D22 
                 5.00 
                 10.41 
                 4.46 
               
               
                   
                   
               
             
          
           
               
                 Aspherical Coefficients 
               
               
                 Thirteenth Surface 
               
               
                   
               
             
          
           
               
                   
                 k = 2.31845e−01 
                   
                   
               
               
                   
                 B = 2.00369e−05 
                 C = 1.608537e−05 
                 D = 4.05874e−07 
               
               
                   
                 E = −3.07187e−09 
               
               
                   
                 A′ −6.48963e−05 
                 B′ = −4.81856e−05 
                 C′ = −3.57450E−06 
               
               
                   
                 D′ = 0 
               
               
                   
                 θgF1 = 0.588 
                 θgF2 = 0.538 
                 θgF3 = 0.543 
               
               
                   
                   
               
             
          
         
       
     
         [0066]    
       
         
               
             
               
               
               
               
             
               
               
             
               
               
               
               
               
             
               
             
               
               
               
               
             
               
               
             
               
             
               
               
               
               
             
               
               
             
               
             
               
               
               
               
             
               
               
             
               
               
               
               
             
           
               
                   
               
               
                   
               
               
                 (Numerical Embodiment 4) 
               
               
                   
               
             
             
               
                 f = 7.40 to 49.93 Fno = 2.45 to 3.60 2ω = 74.2° to 12.8° 
               
               
                   
               
             
          
           
               
                 R1 = 69.953 
                 D1 = 1.80 
                 N1 = 2.003300 
                 ν1 = 28.3 
               
               
                 R2 = 38.458 
                 D2 = 5.40 
                 N2 = 1.696797 
                 ν2 = 55.5 
               
               
                 R3 = 240.106 
                 D3 = 0.20 
               
               
                 R4 = 42.228 
                 D4 = 4.00 
                 N3 = 1.603112 
                 ν3 = 60.6 
               
               
                 R5 = 213.904 
                 D5 = Variable 
               
               
                 R6 = 65.018 
                 D6 = 1.10 
                 N4 = 1.772499 
                 ν4 = 49.6 
               
               
                 R7 = 9.570 
                 D7 = 4.51 
               
               
                 R8 = −92.182 
                 D8 = 0.90 
                 N5 = 1.712995 
                 ν5 = 53.9 
               
               
                 R9 = 20.596 
                 D9 = 1.41 
               
               
                 R10 = 34.712 
                 D10 = 3.30 
                 N6 = 1.846660 
                 ν6 = 23.9 
               
               
                 R11 = −24.754 
                 D11 = 0.42 
               
               
                 R12 = −16.223 
                 D12 = 0.80 
                 N7 = 1.882997 
                 ν7 = 40.8 
               
               
                 R13 = −52.307 
                 D13 = Variable 
               
               
                 R14 = Stop 
                 D14 = 0.80 
               
               
                 R15 = 10.752 
                 D15 = 4.00 
                 N8 = 1.743300 
                 ν8 = 49.3 
               
               
                 R16 = −1517.334 
                 D16 = 4.00 
                 N9 = 1.647689 
                 ν9 = 33.8 
               
               
                 R17 = 9.583 
                 D17 = 1.43 
               
               
                 R18 = 67.785 
                 D18 = 0.80 
                 N10 = 1.603420 
                 ν10 = 38.0 
               
               
                 R19 = 10.688 
                 D19 = 4.60 
                 N11 = 1.496999 
                 ν11 = 81.5 
               
               
                 R20 = −26.644 
                 D20 = 2.00 
               
               
                 R21 = 18.138 
                 D21 = 3.00 
                 N12 = 1.433870 
                 ν12 = 95.1 
               
               
                 R22 = −148.961 
                 D22 = Variable 
               
               
                 R23 = 23.486 
                 D23 = 2.80 
                 N13 = 1.772499 
                 ν13 = 49.6 
               
               
                 R24 = −61.733 
                 D24 = 0.90 
                 N14 = 1.846660 
                 ν14 = 23.9 
               
               
                 R25 = 160.586 
                 D25 = 2.00 
               
               
                 R26 = ∞ 
                 D26 = 2.40 
                 N15 = 1.516330 
                 ν15 = 64.1 
               
               
                 R27 = ∞ 
               
               
                   
               
             
          
           
               
                   
                 Focal Length 
               
             
          
           
               
                   
                 Variable Interval 
                 7.40 
                 24.23 
                 49.93 
               
               
                   
                   
               
               
                   
                 D5 
                 1.50 
                 22.11 
                 33.24 
               
               
                   
                 D13 
                 21.74 
                 7.07 
                 2.62 
               
               
                   
                 D22 
                 3.68 
                 18.43 
                 27.59 
               
               
                   
                   
               
             
          
           
               
                 Aspherical Coefficients 
               
               
                   
               
               
                 Tenth Surface 
               
             
          
           
               
                   
                 k = −5.22197e+00 
                   
                   
               
               
                   
                 B = 6.2067e−05 
                 C = −2.94467e−07 
                 D = −2.08546e−09 
               
               
                   
                 E = 1.581298e−10 
               
             
          
           
               
                   
                 A′ = 0 B′ = 0 C′ = 0 D′ = 0 
               
             
          
           
               
                 Eleventh surface 
               
             
          
           
               
                   
                 k = 1.69413e+00 
                   
                   
               
               
                   
                 B = −5.28431e−06 
                 C = −2.59025e−07 
                 D = −1.09156e−08 
               
               
                   
                 E = −2.01132e−12 
               
             
          
           
               
                   
                 A′ = 0 B′ = 0 C′ = 0 D′ = 0 
               
             
          
           
               
                 Fifteenth Surface 
               
             
          
           
               
                   
                 k = −4.58147e−01 
                   
                   
               
               
                   
                 B = −1.97178e−05 
                 C = 3.87206e−08 
                 D = 0.00000e+00 
               
               
                   
                 E = 0.00000e+00 
               
             
          
           
               
                   
                 A′ = 0 B′ = 0 C′ = 0 C′ = 0 D′ = 0 
               
             
          
           
               
                   
                 θgF1 = 0.598 
                 θgF2 = 0.543 
                 θgF3 = 0.542 
               
               
                   
                   
               
             
          
         
       
     
         [0067]    
       
         
               
             
               
               
               
               
             
               
               
             
               
               
               
               
               
             
               
             
               
               
               
               
             
               
               
             
               
               
               
               
             
           
               
                   
               
               
                   
               
               
                 (Numerical Embodiment 5) 
               
               
                   
               
             
             
               
                 f = 10.70 to 52.00 Fno = 2.47 to 3.60 2ω = 73.6° to 17.5° 
               
               
                   
               
             
          
           
               
                 R1 = 86.597 
                 D1 = 2.20 
                 N1 = 2.003300 
                 ν1 = 28.3 
               
               
                 R2 = 60.933 
                 D2 = 8.00 
                 N2 = 1.487490 
                 ν2 = 70.2 
               
               
                 R3 = 575.874 
                 D3 = 0.20 
               
               
                 R4 = 57.564 
                 D4 = 5.00 
                 N3 = 1.696797 
                 ν3 = 55.5 
               
               
                 R5 = 152.745 
                 D5 = Variable 
               
               
                 R6 = 69.553 
                 D6 = 1.50 
                 N4 = 1.743997 
                 ν4 = 44.8 
               
               
                 R7 = 12.681 
                 D7 = 7.70 
               
               
                 R8 = −87.086 
                 D8 = 1.20 
                 N5 = 1.712995 
                 ν5 = 53.9 
               
               
                 R9 = 31.485 
                 D9 = 0.20 
               
               
                 R10 = 19.959 
                 D10 = 4.80 
                 N6 = 1.805181 
                 ν6 = 25.4 
               
               
                 R11 = 205.190 
                 D11 = 0.70 
               
               
                 R12 = −189.317 
                 D12 = 1.05 
                 N7 = 1.603420 
                 ν7 = 38.0 
               
               
                 R13 = 46.681 
                 D13 = Variable 
               
               
                 R14 = Stop 
                 D14 = 1.40 
               
               
                 R15 = −25.412 
                 D15 = 0.70 
                 N8 = 1.800999 
                 ν8 = 35.0 
               
               
                 R16 = 21.168 
                 D16 = 3.80 
                 N9 = 1.693501 
                 ν9 = 53.2 
               
               
                 R17 = −21.644 
                 D17 = 0.12 
               
               
                 R18 = 40.587 
                 D18 = 3.20 
                 N10 = 1.719995 
                 ν10 = 50.2 
               
               
                 R19 = −49.292 
                 D19 = Variable 
               
               
                 R20 = −31.010 
                 D20 = 2.05 
                 N11 = 1.846660 
                 ν11 = 23.9 
               
               
                 R21 = −16.841 
                 D21 = 0.75 
                 N12 = 1.638539 
                 ν12 = 55.4 
               
               
                 R22 = −4955.327 
                 D22 = Variable 
               
               
                 R23 = −200.777 
                 D23 = 3.00 
                 N13 = 1.583126 
                 ν13 = 59.4 
               
               
                 R24 = −43.989 
                 D24 = 1.40 
               
               
                 R25 = −29.407 
                 D25 = 1.10 
                 N14 = 1.846660 
                 ν14 = 23.9 
               
               
                 R26 = −880.863 
                 D26 = 5.40 
                 N15 = 1.516330 
                 ν15 = 64.1 
               
               
                 R27 = −25.603 
                 D27 = 0.20 
               
               
                 R28 = 92.993 
                 D28 = 5.60 
                 N16 = 1.438750 
                 ν16 = 95.0 
               
               
                 R29 = −36.192 
                 D29 = 0.20 
               
               
                 R30 = 98.165 
                 D30 = 3.80 
                 N17 = 1.438750 
                 ν17 = 95.0 
               
               
                 R31 = −88.335 
                 D31 = 2.00 
               
               
                 R32 = ∞ 
                 D32 = 30.00 
                 N18 = 1.516330 
                 ν18 = 64.1 
               
               
                 R33 = ∞ 
               
               
                   
               
             
          
           
               
                   
                 Focal Length 
               
             
          
           
               
                   
                 Variable Interval 
                 10.70 
                 24.64 
                 52.00 
               
               
                   
                   
               
               
                   
                 D5 
                 1.30 
                 26.39 
                 44.92 
               
               
                   
                 D13 
                 31.71 
                 13.20 
                 3.63 
               
               
                   
                 D19 
                 2.41 
                 13.01 
                 24.00 
               
               
                   
                 D22 
                 23.75 
                 13.15 
                 2.16 
               
               
                   
                   
               
             
          
           
               
                 Aspherical Coefficients 
               
               
                 Twenty-third Surface 
               
               
                   
               
             
          
           
               
                   
                 k = 1.65286e+02 
                   
                   
               
               
                   
                 B = −1.15849e−05 
                 C = 7.11620e−09 
                 D = −6.41580e−11 
               
               
                   
                 E = 3.01107e−13 
               
             
          
           
               
                   
                 A′ = 0 B′ = 0 C′ = D = 0 
               
             
          
           
               
                   
                 θgF1 = 0.598 
                 θgF2 = 0.530 
                 θ= 0.543 
               
               
                   
                   
               
             
          
         
       
     
         [0068]    
       
         
               
             
               
               
               
               
             
               
               
             
               
               
               
               
               
             
               
             
               
               
               
               
             
               
               
             
               
             
               
               
               
               
             
               
               
             
               
               
               
               
             
           
               
                   
               
               
                   
               
               
                 (Numerical Embodiment 6) 
               
               
                   
               
             
             
               
                 f = 7.41 to 72.52 Fno = 2.88 to 3.58 2ω = 63.1° to 7.2° 
               
               
                   
               
             
          
           
               
                 R1 = 82.056 
                 D1 = 1.80 
                 N1 = 2.003300 
                 ν1 = 28.3 
               
               
                 R2 = 44.777 
                 D2 = 7.00 
                 N2 = 1.496999 
                 ν2 = 81.5 
               
               
                 R3 = −135.275 
                 D3 = 0.20 
               
               
                 R4 = 33.670 
                 D4 = 3.90 
                 N3 = 1.696797 
                 ν3 = 55.5 
               
               
                 R5 = 84.120 
                 D5 = Variable 
               
               
                 R6 = 66.631 
                 D6 = 1.00 
                 N4 = 1.834807 
                 ν4 = 42.7 
               
               
                 R7 = 9.527 
                 D7 = 5.70 
               
               
                 R8 = −29.340 
                 D8 = 0.85 
                 N5 = 1.693501 
                 ν5 = 53.2 
               
               
                 R9 = −2211.790 
                 D9 = 0.55 
               
               
                 R10 = 16.193 
                 D10 = 3.50 
                 N6 = 1.846660 
                 ν6 = 23.8 
               
               
                 R11 = −1439.057 
                 D11 = 0.75 
                 N7 = 1.834807 
                 ν7 = 42.7 
               
               
                 R12 = 22.440 
                 D12 = Variable 
               
               
                 R13 = Stop 
                 D13 = 2.30 
               
               
                 R14 = 84.265 
                 D14 = 2.20 
                 N8 = 1.696797 
                 ν8 = 55.5 
               
               
                 R15 = −57.073 
                 D15 = 0.80 
               
               
                 R16 = 51.890 
                 D16 = 2.90 
                 N9 = 1.603112 
                 ν9 = 60.6 
               
               
                 R17 = −18.152 
                 D17 = 0.60 
                 N10 = 1.846660 
                 ν10 = 23.8 
               
               
                 R18 = −38.609 
                 D18 = Variable 
               
               
                 R19 = −23.221 
                 D19 = 2.10 
                 N11 = 1.688931 
                 ν11 = 31.1 
               
               
                 R20 = −12.964 
                 D20 = 0.70 
                 N12 = 1.516330 
                 ν12 = 64.1 
               
               
                 R21 = 84.262 
                 D21 = Variable 
               
               
                 R22 = 36.632 
                 D22 = 3.00 
                 N13 = 1.696797 
                 ν13 = 55.5 
               
               
                 R23 = −37.800 
                 D23 = 0.20 
               
               
                 R24 = 17.310 
                 D24 = 3.20 
                 N14 = 1.487490 
                 ν14 = 70.2 
               
               
                 R25 = −46.830 
                 D25 = 0.70 
                 N15 = 1.761821 
                 ν15 = 26.5 
               
               
                 R26 = 21.385 
                 D26 = 1.00 
               
               
                 R27 = 143.259 
                 D27 = 1.80 
                 N16 = 1.583126 
                 ν16 = 59.4 
               
               
                 R28 = −60.970 
                 D28 = Variable 
               
               
                 R29 = ∞ 
                 D29 = 3.06 
                 N17 = 1.516330 
                 ν17 = 64.2 
               
               
                 R30 = ∞ 
               
               
                   
               
             
          
           
               
                   
                 Focal Length 
               
             
          
           
               
                   
                 Variable Interval 
                 7.41 
                 29.98 
                 72.52 
               
               
                   
                   
               
               
                   
                 D5 
                 1.00 
                 23.75 
                 34.45 
               
               
                   
                 D12 
                 35.25 
                 12.50 
                 1.80 
               
               
                   
                 D18 
                 2.87 
                 10.36 
                 7.33 
               
               
                   
                 D21 
                 13.25 
                 2.39 
                 6.64 
               
               
                   
                 D28 
                 5.00 
                 8.38 
                 7.16 
               
               
                   
                   
               
             
          
           
               
                 Aspherical Coefficients 
               
               
                   
               
               
                 Nineteenth Surface 
               
             
          
           
               
                   
                 k = −6.05759e−01 
                   
                   
               
               
                   
                 B = −1.24549e−05 
                 C = −2.17570e−07 
                 D = 5.45193e−09 
               
               
                   
                 E = 0.00000e+00 
               
             
          
           
               
                   
                 A′ = 0 B′ = 0 C′ = 0 D′ = 0 
               
             
          
           
               
                 Twenty-eighth Surface 
               
             
          
           
               
                   
                 k = −6.05759e−01 
                   
                   
               
               
                   
                 B = −2.71750e−01 
                 C = −1.89532e−07 
                 D = 3.70239e−09 
               
               
                   
                 E = 0.00000e+00 
               
             
          
           
               
                   
                 A′ = 0 B′ = 0 C′ = 0 D′ = 0 
               
             
          
           
               
                   
                 θgF1 = 0.598 
                 θgF2 = 0.538 
                 θgF3 = 0.543 
               
               
                   
                   
               
             
          
         
       
     
         [0069]    
       
         
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                   
               
               
                 Conditional 
                 Numerical Embodiment 
               
             
          
           
               
                 Formula 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
               
               
                   
               
             
          
           
               
                 (1) 
                 28.3 
                 28.3 
                 33.3 
                 28.3 
                 28.3 
                 28.3 
               
               
                 (2) Left side 
                 0.598 
                 0.598 
                 0.588 
                 0.598 
                 0.598 
                 0.598 
               
               
                 (2) Right side 
                 0.604 
                 0.604 
                 0.590 
                 0.604 
                 0.604 
                 0.604 
               
               
                 (3) 
                 1.498 
                 1.697 
                 1.236 
                 1.303 
                 2.122 
                 1.746 
               
               
                 (4) 
                 0.685 
                 0.652 
                 0.709 
                 1.347 
                 1.941 
                 0.795 
               
               
                 (5) 
                 0.466 
                 0.466 
                 0.490 
                 0.560 
                 0.662 
                 0.497 
               
               
                 (6) 
                 −0.0016 
                 −0.0011 
                 −0.0010 
                 −0.0017 
                 −0.0016 
                 −0.0011 
               
               
                 (7) 
                 2.0033 
                 2.0033 
                 1.8061 
                 2.0033 
                 2.0033 
                 2.0033 
               
               
                 (2a) Right side 
                 0.600 
                 0.600 
                 0.586 
                 0.600 
                 0.600 
                 0.600 
               
               
                   
               
             
          
         
       
     
         [0070]     Next, an example of an optical appliance using the zoom lenses of Embodiments 1 to 6 will be described with reference to  FIGS. 14 and 15 .  
         [0071]      FIG. 14  shows an example using the zoom lens system of the present invention for a video camera. In  FIG. 14 , reference numeral  10  denotes a camera body,  11  denotes an image taking optical system composed of any one of the zoom lenses of Examples 1 to 5,  12  denotes a solid-state image pickup element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor for receiving an object image formed by the image taking optical system  11 ,  13  denotes a memory for recording the object image received by the solid-state image pickup element  12 , and  14  denotes a finder for observing the object image. Examples of the finder  14  include an optical finder and a finder for observing an object image displayed on a display element such as a liquid crystal panel.  
         [0072]      FIG. 15  shows an example using the zoom lens system of the present invention for a digital still camera. In  FIG. 15 , reference numeral  20  denotes a camera body,  21  denotes an image taking optical system composed of any of the zoom lenses described in Examples 1 to 5,  22  denotes a solid-state image pickup element (photoelectric conversion element) such as a CCD sensor and a CMOS sensor for receiving an object image formed by the image taking optical system  21 ,  23  denotes a memory for recording information corresponding to the object image photoelectrically converted by the solid-state image pickup element  22 , and  24  denotes a finder for observing the object image formed on the solid-state image pickup element  22 , composed of a liquid crystal display panel.  
         [0073]     Thus, by applying the zoom lens system of the present invention to an image pickup apparatus such as a video camera and a digital still camera, a small image pickup apparatus having high optical performance can be realized.  
         [0074]     This application claims priority from Japanese Patent Application No. 2004-167215 filed Jun. 4, 2004, which is hereby incorporated by reference herein.