Abstract:
The invention relates to a zoom lens that enables an optical path to be easily bent by a reflecting optical element, has a wide-angle design and high optical performance as represented by a high zoom ratio of about 3.4, is extremely slimmed down in the depth direction, and costs less. The zoom lens comprises a positive first lens group G 1 , a negative second lens group G 2 , a positive third lens group G 3 , a positive fourth lens group G 4  and a negative fifth lens group G 5 . Upon zooming from the wide-angle end to the telephoto end, the first lens group G 1  remains substantially fixed with respect to an image plane I, and at least the second G 2  and the fourth lens group G 4  move. The first lens group G 1  includes a reflecting optical element for bending the optical path involved, and a portion of the first lens group G 1  on an object side with respect to the reflecting surface has negative refracting power. The zoom lens satisfies condition (1) with respect to the focal length of the fifth lens group G 5.

Description:
[0001]    This application claims benefits of Japanese Application No. 2006-260178 filed in Japan on Sep. 26, 2006, the contents of which are incorporated herein by this reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates generally to a zoom lens and an imaging system using the same, and more particularly to a zoom lens with the optical axis of its optical system bent and an imaging system incorporating the same. 
         [0003]    In recent years, digital cameras (electronic cameras) have received attention as the coming generation of cameras, an alternative to silver-halide 35 mm-film (135-format) cameras. Currently available digital cameras are broken down into some. categories in a wide range from the high-end type for commercial use to the portable low-end type. 
         [0004]    In view of the category of the portable low-end type in particular, the primary object of the present invention is to provide the technology for implementing easy-to-use, high-zoom-ratio, less costly video or digital cameras whose depth dimension is reduced while high image quality is ensured, and which have zoom ratios high enough to cover a wide focal length range from the wide-angle end to the telephoto end. 
         [0005]    The gravest bottleneck in diminishing the depth dimension of cameras is the thickness of an optical system, especially a zoom lens system from the surface located nearest to its object side to an imaging plane. The technology currently in vogue for slimming down camera bodies makes use of a so-called collapsible lens mount that allows the optical system to be taken out of the camera body for shooting and received therein for carrying around. 
         [0006]    However, the use of the collapsible lens mount is not preferable in view of ease of operation, because some time is taken for sending the zoom lens received at it ready for use. Making the lens group nearest to the object side movable is again not preferable for prevention of entrance of moisture and dust. More recent years have seen a camera version that takes no waiting time for sending it ready for use (for booting a zoom lens up); it works favorably for prevention of entrance of moisture and dust and is much more slimmed down in its depth direction by use of an optical system with an optical path (optical axis) bent by a reflecting optical member such as a mirror or a prism. In a typical camera of this version, the lens group nearest to the object side of the zoom lens is fixed in terms of position and the reflecting optical member is received in that lens group, so that the subsequent optical path is bent longitudinally or transversely with respect to a camera body, thereby reducing the depth-direction dimension as much as possible. 
         [0007]    For the time being, most video or digital cameras under the portable category to which the invention is directed would have a half angle of view of about 30° at the wide-angle end; however, wide-angle cameras having a greater taking range will come out anyway. 
         [0008]    For instance, Patent Publication 1 comes up with a typical wide-angle zoom lens relying upon a bent optical system. However, that zoom lens has a half angle of view of as large as about 37°, yet the zoom ratio remains at barely about 2.8. On the other hand, the zoom lens of Patent Publication 2 has a half angle of view of about 37° and a zoom ratio of about 3.7, yet its full length is still long. 
         [0009]    Patent Publication 1 
         [0010]    JP(A)2004-354871 
         [0011]    Patent Publication 2 
         [0012]    JP(A)2004-354869 
       SUMMARY OF THE INVENTION 
       [0013]    In consideration of such problems with the prior art as briefed above, the primary object of the invention is to provide a zoom lens that can instantaneously send a camera ready for use (with no waiting time for boosting the zoom lens up) as is not the case with a collapsible lens mount camera, and is preferable for prevention of entrance of moisture and dust. According to the invention, the optical path (optical axis) of the optical system can be easily bent by means of a reflecting optical member such as a prism so that a camera, when the zoom lens of the invention is applied to it, can be much more reduced in terms of depth-direction thickness. Further, that zoom lens is of a wide-angle arrangement that has high optical performance as represented by a zoom ratio of as high as about 3.4, is very thin in the depth direction, and costs less. 
         [0014]    According to the invention, the aforesaid object is accomplished by the provision of a zoom lens comprising, in order from its object side, a first lens group having positive power, a second lens group having negative power, a third lens group having positive power, a fourth lens group having positive power and a fifth lens group having negative power, characterized in that: 
         [0015]    upon zooming from the wide-angle end to the telephoto end of the zoom lens, said first lens group remains fixed with respect to an image plane, and at least said second lens group and said fourth lens group moves, 
         [0016]    said first lens group includes a reflecting optical element for bending an optical path and has negative refracting power on an object side with respect to a reflecting surface, and 
         [0017]    said zoom lens satisfies the following condition (1): 
         [0000]      1.5 &lt;|f   5   /f   w |&lt;2.7 . . .   (1) 
         [0000]    where f 5  is the focal length of the fifth lens group, and 
         [0018]    f w  is the focal length of the whole zoom lens system at the wide-angle end. 
         [0019]    The advantages of, and the requirements for, the aforesaid arrangement according to the invention are now explained. 
         [0020]    By allowing the zoom lens of the invention to have such arrangement as mentioned above, the optical path involved can be bent at the first lens group thereby slimming down the zoom lens in the depth direction, and by allowing the second and the fourth lens group to be movable, they can share the load of zooming so that the zoom lens can have a high zoom ratio. By allowing the fifth lens group to have negative power and enlarge light beams, the focal lengths of the first and the fourth lens group can be so curtailed that compactness is achievable. As the angle of view grows wide, it causes lens diameter to grow large, and distortion to become large. By locating negative refracting power on an object side with respect to a reflecting surface in the first lens group, however, the lens diameter can be diminished, and by locating negative power in the fifth lens group, distortion produced at the first lens group can be canceled out. Further, allowing the first lens group to remain fixed with respect to the image plane takes no time for sending the associated camera ready for use, and is preferable for prevention of moisture and dust as well. 
         [0021]    Condition (1) provides a proper definition of the power of the first lens group; as the upper limit of 2.7 is exceeded, it will cause the power of the fifth lens group to become weak, rendering compactness difficult, and as the lower limit of 1.5 is not reached, it will render correction of field curvature difficult. 
         [0022]    For the zoom lens arrangement of the invention, it is preferable to fix the third lens group during zooming. By allowing the third lens group to remain fixed during zooming, it is possible to locate an aperture stop near that to diminish lens diameter. 
         [0023]    Preferably, the fifth lens group at least comprises a cemented lens and a positive lens. If the power of the fifth lens group is strong enough to achieve compactness, there is then a worsening of the Petzval&#39;s sum; however, if the cemented lens and the positive lens are properly located, it is then possible to keep the image plane in a good condition. 
         [0024]    Preferably, the first lens group comprises, in order from its object side, a negative lens and a prism that is a reflecting optical element. If the negative lens is located nearest to the object side and the optical path is bent after that, it is then possible to make the associated camera thin. Further, the location of the negative lens in the first lens group enables the effective diameter to be smaller. Furthermore, the use of the prism as the reflecting optical element keeps the length of the optical path so short that the spacing between the first lens and the aperture stop can be curtailed. It is in turn possible to keep the entrance pupil shallow and achieve compactness. 
         [0025]    Preferably, the zoom lens of the invention satisfies the following condition (2). 
         [0000]      0.8 &lt;|f   2   /f   w |&lt;1.5 . . .   (2) 
         [0000]    Here f 2  is the focal length of the second lens group. 
         [0026]    Condition (2) provides a proper definition of the power of the second lens group. As the lower limit of 0.8 to that is not reached or the power of the second lens group grows strong, it may work for curtailing the whole length of the zoom lens because the amount of movement of the second lens group remains small; however, there will be some considerable astigmatism and distortion occurring, which render it difficult to correct the whole zoom lens system for aberrations. As the upper limit of 1.5 is exceeded, that will render it difficult to keep the whole length short. 
         [0027]    Preferably, the zoom lens of the invention satisfies the following condition (3). 
         [0000]      2.0 &lt;f   1   /f   w &lt;5.0 . . .   (3) 
         [0000]    Here f 1  is the focal length of the first lens group. 
         [0028]    Condition (3) provides a proper definition of the power of the first lens group. At greater than the upper limit of 0.5, the entrance pupil will grow deep, resulting in an increased lens diameter. At less than the lower limit of 2.0, correction of off-axis aberrations and chromatic aberrations will become difficult. 
         [0029]    Preferably, the zoom lens of the invention satisfies the following condition (4). 
         [0000]      1.0 &lt;|f   1L1   /f   w |&lt;3.0 . . .   (4) 
         [0000]    Here f 1L1  is the focal length of a system of the first lens group on an object side with respect to the reflecting surface therein. 
         [0030]    Condition (4) provides a proper definition of the power of the negative lens in the first lens group. To make the entrance pupil shallow thereby enabling the optical path to be physically bent, it is preferable to make the power of the negative lens in the first lens group strong. At greater than the upper limit of 3.0, the entrance pupil will remain deep, and an effort to make sure some angle of view will result in an increase in the diameter and size of the respective optical elements that form the first lens group, which will render it physically unfeasible to bend the optical path. At less than the lower limit of 1.0, the magnification that can be taken by the lens groups that follow the first lens group and move for zooming will be close to zero, offering such problems as an increase in the amount of their movement and a decreased zoom ratio. At the same time, it will be difficult to correct off-axis aberrations such as distortion and chromatic aberrations. 
         [0031]    For the first lens group, it is also preferable that the negative lens comprises an aspheric surface. The negative lens in the first lens group receives rim rays of some height upon zooming at the wide-angle end, producing very large off-axis aberrations. As the power of the negative lens grows strong to keep the entrance pupil shallow, some considerable aberrations are going to be produced; it is desired to make use of the aspheric surface to correct those aberrations. Further, the curvature of that surface is so relaxed that there is less deterioration caused by production errors, and a lot more contribution to a reduction of the depth dimension of the associated camera as well. 
         [0032]    It is noted that the invention also includes an imaging system using such a zoom lens as mentioned above. It is then preferable that a low-pass filter is interposed between the zoom lens and an imaging device. 
         [0033]    As can be seen from the explanations given above, the present invention can successfully provide a zoom lens that can instantaneously send a camera ready for use (with no waiting time for boosting the zoom lens up) as is not the case with a collapsible lens mount camera, and is preferable for prevention of entrance of moisture and dust. With the arrangement of the invention, the optical path (optical axis) of the optical system can be easily bent by means of a reflecting optical member such as a prism so that a camera, when the zoom lens of the invention is applied to it, can be much more reduced in terms of depth-direction thickness. Further, that zoom lens is of a wide-angle arrangement that has high optical performance as represented by a zoom ratio of as high as about 3.4, is very thin in the depth direction, and costs less. 
         [0034]    Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification. 
         [0035]    The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts that will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0036]      FIG. 1  is illustrative in optically taken-apart form of Example 1 of the inventive zoom lens at the wide-angle end (a), in an intermediate state (b) and at the telephoto end (c) upon focusing on an object point at infinity. 
           [0037]      FIG. 2  is illustrative in optically taken-apart form, as in  FIG. 1 , of Example 2 of the inventive zoom lens. 
           [0038]      FIG. 3  is illustrative in optically taken-apart form, as in  FIG. 1 , of Example 3 of the inventive zoom lens. 
           [0039]      FIG. 4  is illustrative in optically taken-apart form, as in  FIG. 1 , of Example 4 of the inventive zoom lens. 
           [0040]      FIG. 5  is illustrative in optically taken-apart form, as in  FIG. 1 , of Example 5 of the inventive zoom lens. 
           [0041]      FIG. 6  is indicative of aberrations of Example 1 at the wide-angle end (a), in the intermediate state (b), and at the telephoto end (c) upon focusing on an object point at infinity. 
           [0042]      FIG. 7  is indicative, as in  FIG. 6 , of aberrations of Example 2. 
           [0043]      FIG. 8  is indicative, as in  FIG. 6 , of aberrations of Example 3. 
           [0044]      FIG. 9  is indicative, as in  FIG. 6 , of aberrations of Example 4. 
           [0045]      FIG. 10  is indicative, as in  FIG. 6 , of aberrations of Example 5. 
           [0046]      FIG. 11  is a front perspective schematic illustrative of the appearance of a digital camera with the inventive zoom lens built therein. 
           [0047]      FIG. 12  is a rear perspective schematic of the digital camera of  FIG. 11 . 
           [0048]      FIG. 13  is a sectional schematic of the digital camera of  FIG. 11 . 
           [0049]      FIG. 14  is a block diagram of internal circuits in the main part of the digital camera. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0050]    The zoom lens of the invention is now explained with reference to Examples 1, 2, 3, 4 and 5.  FIGS. 1 ,  2 ,  3 ,  4  and  5  are illustrative in optically taken-apart form of Examples 1, 2, 3, 4 and 5 at the wide-angle ends, in intermediate states and at the telephoto ends, respectively, upon focusing on an infinite object point. Throughout  FIGS. 1 to 5 , G 1  stands for the first lens group, G 2  the second lens group, G 3  the third lens group, S an aperture stop, G 4  the fourth lens group, G 5  the fifth lens group, F an optical low-pass filter, G a cover glass for a CCD that is an electronic imaging device, and I the image plane of CCD. It is noted that an optical path bending prism as the reflecting optical member located in the first lens group G 1  is shown in the form of a plane-parallel plate P with taken-apart optical paths, and no reflecting surface is given. A near infrared sharp cut coating, for instance, could be applied directly onto the optical low-pass filter F, or there could be another infrared cut absorption filter separately located. Alternatively, the near infrared sharp cut coating could be applied onto the entrance surface of a transparent flat plate. 
       EXAMPLE 1  
       [0051]    As shown in  FIG. 1 , this example is directed to a zoom lens made up of, in order from its object side, the first lens group G 1  that has positive power and remains fixed during zooming, the second lens group G 2  that has negative power and moves toward the image side from the wide-angle end to the telephoto end in such a way as to be positioned on the image side at the telephoto end rather than at the wide-angle end upon zooming, the third lens group G 3  that has positive power and remains fixed during zooming, the aperture stop S that remains fixed during zooming, the fourth lens group G 4  that has positive power and moves toward the object side from the wide-angle end to the telephoto end in such a way as to be positioned on the object side at the telephoto end rather than at the wide-angle end upon zooming, and the fifth lens group G 5  that has negative power and remains fixed during zooming. A prism P located in the first lens group G 1  works bending (flexing) an optical path. 
         [0052]    In order from the object side of the zoom lens, the first lens group G 1  is made up of a negative meniscus lens convex on its object side, the prism P and a double-convex positive lens; the second lens group G 2  is made up of a negative meniscus lens convex on its object side and a cemented lens consisting of a double-concave negative lens and a double-convex positive lens; the third lens group G 3  is made up of one double-convex positive lens; the fourth lens group G 4  is made up of a cemented lens consisting of a double-convex positive lens and a negative meniscus lens concave on its object side; and the fifth lens group G 5  is made of a cemented lens consisting of a double-concave negative lens and a positive meniscus lens convex on its object side and a double-convex positive lens. 
         [0053]    Five aspheric surfaces are used: two at both surfaces of the double-convex positive lens in the first lens group G 1 , two at both surfaces of the double-convex positive lens in the third lens group G 3 , and one at the surface nearest to the object side of the cemented lens in the fourth lens group G 4 . 
       EXAMPLE 2  
       [0054]    As shown in  FIG. 2 , this example is directed to a zoom lens made up of, in order from its object side, the first lens group G 1  that has positive power and remains fixed during zooming, the second lens group G 2  that has negative power and moves toward the image side from the wide-angle end to the telephoto end in such a way as to be positioned on the image side at the telephoto end rather than at the wide-angle end upon zooming, the third lens group G 3  that has positive power and remains fixed during zooming, the aperture stop S that remains fixed during zooming, the fourth lens group G 4  that has positive power and moves toward the object side from the wide-angle end to the telephoto end in such a way as to be positioned on the object side at the telephoto end rather than at the wide-angle end upon zooming, and the fifth lens group G 5  that has negative power and remains fixed during zooming. A prism P located in the first lens group G 1  works bending (flexing) an optical path. 
         [0055]    In order from the object side of the zoom lens, the first lens group G 1  is made up of a double-concave negative lens, the prism P and a double-convex positive lens; the second lens group G 2  is made up of a negative meniscus lens convex on its object side and a cemented lens consisting of a double-concave negative lens and a double-convex positive lens; the third lens group G 3  is made up of one double-convex positive lens; the fourth lens group G 4  is made up of a cemented lens consisting of a double-convex positive lens and a negative meniscus lens concave on its object side; and the fifth lens group G 5  is made of a cemented lens consisting of a double-concave negative lens and a double-convex positive lens and a positive meniscus lens convex on its object side. 
         [0056]    Six aspheric surfaces are used: one at the image-side surface of the double-concave negative lens in the first lens group G 1 , two at both surfaces of the double-convex positive lens in the first lens group G 1 , two at both surfaces of the double-convex positive lens in the third lens group G 3 , and one at the surface nearest to the object side of the cemented lens in the fourth lens group G 4 . 
       EXAMPLE 3  
       [0057]    As shown in  FIG. 3 , this example is directed to a zoom lens made up of, in order from its object side, the first lens group G 1  that has positive power and remains fixed during zooming, the second lens group G 2  that has negative power and moves toward the image side from the wide-angle end to the telephoto end in such a way as to be positioned on the image side at the telephoto end rather than at the wide-angle end upon zooming, the third lens group G 3  that has positive power and remains fixed during zooming, the aperture stop S that remains fixed during zooming, the fourth lens group G 4  that has positive power and moves toward the object side from the wide-angle end to the telephoto end in such a way as to be positioned on the object side at the telephoto end rather than at the wide-angle end upon zooming, and the fifth lens group G 5  that has negative power and remains fixed during zooming. A prism P located in the first lens group G 1  works bending (flexing) an optical path. 
         [0058]    In order from the object side of the zoom lens, the first lens group G 1  is made up of a negative meniscus lens convex on its object side, the prism P and a double-convex positive lens; the second lens group G 2  is made up of a negative meniscus lens convex on its object side and a cemented lens consisting of a double-concave negative lens and a positive meniscus lens convex on its object side; the third lens group G 3  is made up of one double-convex positive lens; the fourth lens group G 4  is made up of a cemented lens consisting of a double-convex positive lens and a negative meniscus lens concave on its object side; and the fifth lens group G 5  is made of a cemented lens consisting of a double-concave negative lens and a positive meniscus lens convex on its object side and a double-convex positive lens. 
         [0059]    Five aspheric surfaces are used: two at both surfaces of the double-convex positive lens in the first lens group G 1 , two at both surfaces of the double-convex positive lens in the third lens group G 3 , and one at the surface nearest to the object side of the cemented lens in the fourth lens group G 4 . 
       EXAMPLE 4  
       [0060]    As shown in  FIG. 4 , this example is directed to a zoom lens made up of, in order from its object side, the first lens group G 1  that has positive power and remains fixed during zooming, the second lens group G 2  that has negative power and moves toward the image side from the wide-angle end to the telephoto end in such a way as to be positioned on the image side at the telephoto end rather than at the wide-angle end upon zooming, the third lens group G 3  that has positive power and remains fixed during zooming, the aperture stop S that remains fixed during zooming, the fourth lens group G 4  that has positive power and moves toward the object side from the wide-angle end to the telephoto end in such a way as to be positioned on the object side at the telephoto end rather than at the wide-angle end upon zooming, and the fifth lens group G 5  that has negative power and remains fixed during zooming. A prism P located in the first lens group G 1  works bending (flexing) an optical path. 
         [0061]    In order from the object side of the zoom lens, the first lens group G 1  is made up of a negative meniscus lens convex on its object side, the prism P and a double-convex positive lens; the second lens group G 2  is made up of a negative meniscus lens convex on its object side and a cemented lens consisting of a double-concave negative lens and a positive meniscus lens convex on its object side; the third lens group G 3  is made up of one double-convex positive lens; the fourth lens group G 4  is made up of a cemented lens consisting of a double-convex positive lens and a negative meniscus lens concave on its object side; and the fifth lens group G 5  is made of a cemented lens consisting of a double-concave negative lens and a positive meniscus lens convex on its object side and a double-convex positive lens. 
         [0062]    Five aspheric surfaces are used: two at both surfaces of the double-convex positive lens in the first lens group G 1 , two at both surfaces of the double-convex positive lens in the third lens group G 3 , and one at the surface nearest to the object side of the cemented lens in the fourth lens group G 4 . 
       EXAMPLE 5  
       [0063]    As shown in  FIG. 5 , this example is directed to a zoom lens made up of, in order from its object side, the first lens group G 1  that has positive power and remains fixed during zooming, the second lens group G 2  that has negative power and moves toward the image side from the wide-angle end to the telephoto end in such a way as to be positioned on the image side at the telephoto end rather than at the wide-angle end upon zooming, the third lens group G 3  that has positive power and remains fixed during zooming, the aperture stop S that remains fixed during zooming, the fourth lens group G 4  that has positive power and moves toward the object side from the wide-angle end to the telephoto end in such a way as to be positioned on the object side at the telephoto end rather than at the wide-angle end upon zooming, and the fifth lens group G 5  that has negative power and remains fixed during zooming. A prism P located in the first lens group G 1  works bending (flexing) an optical path. 
         [0064]    In order from the object side of the zoom lens, the first lens group G 1  is made up of a cemented lens of two negative meniscus lenses, each convex on its object side, the prism P and a double-convex positive lens; the second lens group G 2  is made up of a negative meniscus lens convex on its object side and a cemented lens consisting of a double-concave negative lens and a double-convex positive lens; the third lens group G 3  is made up of one double-convex positive lens; the fourth lens group G 4  is made up of a cemented lens consisting of a double-convex positive lens and a negative meniscus lens concave on its object side; and the fifth lens group G 5  is made of a cemented lens consisting of a double-concave negative lens and a positive meniscus lens convex on its object side and a positive meniscus lens convex on its object side. 
         [0065]    Six aspheric surfaces are used: one at the cementing surface of the cemented lens in the first lens group G 1 , two at both surfaces of the double-convex positive lens in the first lens group G 1 , two at both surfaces of the double-convex positive lens in the third lens group G 3 , and one at the surface nearest to the object side of the cemented lens in the fourth lens group G 4 . 
         [0066]    Numerical data about each of Examples 1, 2, 3, 4 and 5 are enumerated below. The symbols used hereinafter but not hereinbefore have the following meanings. 
         [0067]    f: focal length of the zoom lens system, 
         [0068]    F NO : F-number, 
         [0069]    2ω: full angle of view, 
         [0070]    WE: wide-angle end, 
         [0071]    ST: intermediate state, 
         [0072]    TE: telephoto end, 
         [0073]    r 1 , r 2  . . . : radius of curvature of each lens surface, 
         [0074]    d 1 , d 2  . . . : space between adjacent lens surfaces, 
         [0075]    n d1 , n d2  . . . : d-line refractive index of each lens, and 
         [0076]    V d1 , V d2  . . . : Abbe constant of each lens. 
         [0000]    Here let x be an optical axis provided that the direction of travel of light is positive and y be a direction orthogonal to the optical axis. Then, aspheric shape is given by 
         [0000]        x =( y   2   /r )/[1+{1−( K+ 1)( y/r ) 2 } 1/2   ]+A   4   y   4   +A   6   y   6   +A   8   y   8   +A   10   y   10    
         [0000]    where r is a paraxial radius of curvature, K is a conical coefficient, and A 4 , A 6 , A 8  and A 10  are the 4 th -, 6 th -, 8 th -, and 10 th -order aspheric coefficients, respectively. 
       EXAMPLE 1 
       [0077]      
         [0000]    
       
         
               
               
               
               
             
               
             
               
               
             
               
             
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 r 1  = 79.245 
                 d 1  = 0.80 
                 n d1  = 2.00069 
                 ν d1  = 25.46 
               
               
                 r 2  = 10.737 
                 d 2  = 1.85 
               
               
                 r 3  = ∞ 
                 d 3  = 8.40 
                 n d2  = 2.00330 
                 ν d2  = 28.27 
               
               
                 r 4  = ∞ 
                 d 4  = 0.30 
               
               
                 r 5  = 15.402 (Aspheric) 
                 d 5  = 2.67 
                 n d3  = 1.76802 
                 ν d3  = 49.24 
               
               
                 r 6  = −22.552 (Aspheric) 
                 d 6  = (Variable) 
               
               
                 r 7  = 40.183 
                 d 7  = 0.50 
                 n d4  = 1.88300 
                 ν d4  = 40.76 
               
               
                 r 8  = 7.191 
                 d 8  = 1.07 
               
               
                 r 9  = −14.386 
                 d 9  = 0.45 
                 n d5  = 1.88300 
                 ν d5  = 40.76 
               
               
                 r 10  = 8.265 
                 d 10  = 1.15 
                 n d6  = 1.92286 
                 ν d6  = 20.88 
               
               
                 r 11  = −8422.538 
                 d 11  = 
               
               
                   
                 (Variable) 
               
               
                 r 12  = 9.608 (Aspheric) 
                 d 12  = 1.54 
                 n d7  = 1.62299 
                 ν d7  = 58.12 
               
               
                 r 13  = −38.385 (Aspheric) 
                 d 13  = 1.00 
               
               
                 r 14  = ∞ (Stop) 
                 d 14  = 
               
               
                   
                 (Variable) 
               
               
                 r 15  = 8.672 (Aspheric) 
                 d 15  = 2.61 
                 n d8  = 1.62299 
                 ν d8  = 58.12 
               
               
                 r 16  = −6.739 
                 d 16  = 0.54 
                 n d9  = 1.92286 
                 ν d9  = 20.88 
               
               
                 r 17  = −11.899 
                 d 17  = 
               
               
                   
                 (Variable) 
               
               
                 r 18  = −44.226 
                 d 18  = 0.50 
                 n d10  = 2.00330 
                 ν d10  = 28.27 
               
               
                 r 19  = 4.235 
                 d 19  = 2.37 
                 n d11  = 1.51633 
                 ν d11  = 64.14 
               
               
                 r 20  = 9.498 
                 d 20  = 0.94 
               
               
                 r 21  = 10.761 
                 d 21  = 1.80 
                 n d12  = 1.84666 
                 ν d12  = 23.78 
               
               
                 r 22  = −602.041 
                 d 22  = 3.88 
               
               
                 r 23  = ∞ 
                 d 23  = 0.50 
                 n d13  = 1.51680 
                 ν d13  = 64.20 
               
               
                 r 24  = ∞ 
                 d 24  = 0.50 
               
               
                 r 25  = ∞ 
                 d 25  = 0.50 
                 n d14  = 1.51680 
                 ν d14  = 64.20 
               
               
                 r 26  = ∞ 
                 d 26  = 0.37 
               
               
                 r 27  = ∞ (Imaging plane) 
               
               
                   
               
             
          
           
               
                 Aspherical Coefficients 
               
               
                   
               
             
          
           
               
                   
                 5th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −8.79913 × 10 −5   
               
               
                   
                 A 6  = 4.89886 × 10 −7   
               
               
                   
                 A 8  = −3.64842 × 10 −8   
               
               
                   
                 A 10  = 2.72077 × 10 −10   
               
               
                   
                 6th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −3.45410 × 10 −5   
               
               
                   
                 A 6  = 6.14987 × 10 −7   
               
               
                   
                 A 8  = −4.14321 × 10 −8   
               
               
                   
                 A 10  = 4.54264 × 10 −10   
               
               
                   
                 12th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −3.66208 × 10 −4   
               
               
                   
                 A 6  = −5.90379 × 10 −5   
               
               
                   
                 A 8  = 9.30717 × 10 −6   
               
               
                   
                 A 10  = −5.73359 × 10 −7   
               
               
                   
                 13th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −1.89671 × 10 −4   
               
               
                   
                 A 6  = −5.64567 × 10 −5   
               
               
                   
                 A 8  = 9.30033 × 10 −6   
               
               
                   
                 A 10  = −5.93075 × 10 −7   
               
               
                   
                 15th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −3.48870 × 10 −4   
               
               
                   
                 A 6  = −1.61544 × 10 −5   
               
               
                   
                 A 8  = 2.48258 × 10 −6   
               
               
                   
                 A 10  = −1.23458 × 10 −7   
               
               
                   
                   
               
             
          
           
               
                 Zooming Data (∞) 
               
             
          
           
               
                   
                   
                 WE 
                 ST 
                 TE 
               
               
                   
                   
               
               
                   
                 f (mm) 
                 5.07 
                 9.40 
                 17.40 
               
               
                   
                 FNO 
                 3.60 
                 4.30 
                 5.10 
               
               
                   
                 2ω (°) 
                 80.86 
                 44.35 
                 24.24 
               
               
                   
                 d 6   
                 0.60 
                 6.76 
                 10.79 
               
               
                   
                 d 11   
                 10.69 
                 4.54 
                 0.50 
               
               
                   
                 d 14   
                 6.20 
                 4.32 
                 2.05 
               
               
                   
                 d 17   
                 1.51 
                 3.39 
                 5.66 
               
               
                   
                   
               
             
          
         
       
     
       EXAMPLE 2 
       [0078]      
         [0000]    
       
         
               
               
               
               
             
               
             
               
               
             
               
             
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 r 1  = −153.902 
                 d 1  = 0.80 
                 n d1  = 2.00170 
                 ν d1  = 20.60 
               
               
                 r 2  = 12.979 
                 d 2  = 1.91 
               
               
                 (Aspheric) 
               
               
                 r 3  = ∞ 
                 d 3  = 8.50 
                 n d2  = 1.90366 
                 ν d2  = 31.31 
               
               
                 r 4  = ∞ 
                 d 4  = 0.30 
               
               
                 r 5  = 10.604 
                 d 5  = 2.58 
                 n d3  = 1.80139 
                 ν d3  = 45.45 
               
               
                 (Aspheric) 
               
               
                 r 6  = −74.045 
                 d 6  = (Variable) 
               
               
                 (Aspheric) 
               
               
                 r 7  = 180.770 
                 d 7  = 0.50 
                 n d4  = 1.88300 
                 ν d4  = 40.76 
               
               
                 r 8  = 7.336 
                 d 8  = 1.28 
               
               
                 r 9  = −14.370 
                 d 9  = 0.45 
                 n d5  = 1.88300 
                 ν d5  = 40.76 
               
               
                 r 10  = 8.729 
                 d 10  = 1.15 
                 n d6  = 1.92286 
                 ν d6  = 20.88 
               
               
                 r 11  = −62.471 
                 d 11  = (Variable) 
               
               
                 r 12  = 8.946 
                 d 12  = 1.54 
                 n d7  = 1.67790 
                 ν d7  = 55.34 
               
               
                 (Aspheric) 
               
               
                 r 13  = −116.820 
                 d 13  = 1.00 
               
               
                 (Aspheric) 
               
               
                 r 14  = ∞ (Stop) 
                 d 14  = (Variable) 
               
               
                 r 15  = 9.447 
                 d 15  = 2.58 
                 n d8  = 1.62299 
                 ν d8  = 58.12 
               
               
                 (Aspheric) 
               
               
                 r 16  = −6.914 
                 d 16  = 0.54 
                 n d9  = 1.92286 
                 ν d9  = 20.88 
               
               
                 r 17  = −12.280 
                 d 17  = (Variable) 
               
               
                 r 18  = −20.311 
                 d 18  = 0.50 
                 n d10  = 2.00330 
                 ν d10  = 28.27 
               
               
                 r 19  = 5.042 
                 d 19  = 3.10 
                 n d11  = 1.51633 
                 ν d11  = 64.14 
               
               
                 r 20  = −23.168 
                 d 20  = 0.90 
               
               
                 r 21  = 11.413 
                 d 21  = 1.80 
                 n d12  = 1.84666 
                 ν d12  = 23.78 
               
               
                 r 22  = 14.325 
                 d22 = 3.32 
               
               
                 r 23  = ∞ 
                 d 23  = 0.50 
                 n d13  = 1.51680 
                 ν d13  = 64.20 
               
               
                 r 24  = ∞ 
                 d 24  = 0.50 
               
               
                 r 25  = ∞ 
                 d 25  = 0.50 
                 n d14  = 1.51680 
                 ν d14  = 64.20 
               
               
                 r 26  = ∞ 
                 d 26  = 0.37 
               
               
                 r27 = ∞(Imaging 
               
               
                 plane) 
               
               
                   
               
             
          
           
               
                 Aspherical Coefficients 
               
               
                   
               
             
          
           
               
                   
                 2nd surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −1.79166 × 10 −4   
               
               
                   
                 A 6  = −4.73057 × 10 −9   
               
               
                   
                 A 8  = −2.98332 × 10 −9   
               
               
                   
                 A 10  = 0 
               
               
                   
                 5th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −1.23552 × 10 −4   
               
               
                   
                 A 6  = −1.59616 × 10 −7   
               
               
                   
                 A 8  = −7.97986 × 10 −9   
               
               
                   
                 A 10  = −3.77581 × 10 −11   
               
               
                   
                 6th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = 5.80825 × 10 −5   
               
               
                   
                 A 6  = 3.64807 × 10 −8   
               
               
                   
                 A 8  = −1.36016 × 10 −8   
               
               
                   
                 A 10  = 1.80629 × 10 −10   
               
               
                   
                 12th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −1.30705 × 10 −4   
               
               
                   
                 A 6  = −1.84239 × 10 −5   
               
               
                   
                 A 8  = 5.36309 × 10 −6   
               
               
                   
                 A 10  = −3.20137 × 10 −7   
               
               
                   
                 13th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = 8.59092 × 10 −5   
               
               
                   
                 A 6  = −2.59294 × 10 −5   
               
               
                   
                 A 8  = 7.40107 × 10 −6   
               
               
                   
                 A 10  = −4.60471 × 10 −7   
               
               
                   
                 15th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −3.73446 × 10 −4   
               
               
                   
                 A 6  = 1.40361 × 10 −5   
               
               
                   
                 A 8  = −2.39746 × 10 −6   
               
               
                   
                 A 10  = 1.26173 × 10 −7   
               
               
                   
                   
               
             
          
           
               
                 Zooming Data (∞) 
               
             
          
           
               
                   
                   
                 WE 
                 ST 
                 TE 
               
               
                   
                   
               
               
                   
                 f (mm) 
                 5.07 
                 9.40 
                 17.40 
               
               
                   
                 F NO   
                 3.50 
                 4.20 
                 4.90 
               
               
                   
                 2ω (°) 
                 80.25 
                 43.90 
                 24.24 
               
               
                   
                 d 6   
                 0.60 
                 6.55 
                 10.64 
               
               
                   
                 d 11   
                 10.55 
                 4.60 
                 0.50 
               
               
                   
                 d 14   
                 5.97 
                 4.13 
                 2.05 
               
               
                   
                 d 17   
                 1.51 
                 3.36 
                 5.44 
               
               
                   
                   
               
             
          
         
       
     
       EXAMPLE 3 
       [0079]      
         [0000]    
       
         
               
               
               
               
             
               
             
               
               
             
               
             
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 r 1  = 94.193 
                 d 1  = 0.80 
                 n d1  = 2.00069 
                 ν d1  = 25.46 
               
               
                 r 2  = 10.777 
                 d 2  = 1.90 
               
               
                 r 3  = ∞ 
                 d 3  = 8.40 
                 n d2  = 2.00330 
                 ν d2  = 28.27 
               
               
                 r 4  = ∞ 
                 d 4  = 0.30 
               
               
                 r 5  = 15.253 
                 d 5  = 2.67 
                 n d3  = 1.76802 
                 ν d3  = 49.24 
               
               
                 (Aspheric) 
               
               
                 r 6  = −22.635 
                 d 6  = (Variable) 
               
               
                 (Aspheric) 
               
               
                 r 7  = 30.598 
                 d 7  = 0.50 
                 n d4  = 1.88300 
                 ν d4  = 40.76 
               
               
                 r 8  = 7.008 
                 d 8  = 1.08 
               
               
                 r 9  = −14.944 
                 d 9  = 0.45 
                 n d5  = 1.88300 
                 ν d5  = 40.76 
               
               
                 r 10  = 7.893 
                 d 10  = 1.12 
                 n d6  = 1.92286 
                 ν d6  = 20.88 
               
               
                 r 11  = 162.059 
                 d 11  = (Variable) 
               
               
                 r 12  = 9.600 
                 d 12  = 1.54 
                 n d7  = 1.62299 
                 ν d7  = 58.12 
               
               
                 (Aspheric) 
               
               
                 r 13  = −37.829 
                 d 13  = 1.00 
               
               
                 (Aspheric) 
               
               
                 r 14  = ∞ (Stop) 
                 d 14  = (Variable) 
               
               
                 r 15  = 8.474 
                 d 15  = 2.66 
                 n d8  = 1.62299 
                 ν d8  = 58.12 
               
               
                 (Aspheric) 
               
               
                 r 16  = −6.619 
                 d 16  = 0.54 
                 n d9  = 1.92286 
                 ν d9  = 20.88 
               
               
                 r 17  = −11.728 
                 d 17  = (Variable) 
               
               
                 r 18  = −29.689 
                 d 18  = 0.50 
                 n d10  = 2.00330 
                 ν d10  = 28.27 
               
               
                 r 19  = 4.379 
                 d 19  = 2.19 
                 n d11  = 1.51633 
                 ν d11  = 64.14 
               
               
                 r 20  = 10.038 
                 d 20  = 0.97 
               
               
                 r 21  = 12.327 
                 d 21  = 1.80 
                 n d12  = 1.84666 
                 ν d12  = 23.78 
               
               
                 r 22  = −68.566 
                 d 22  = 4.01 
               
               
                 r 23  = ∞ 
                 d 23  = 0.50 
                 n d13  = 1.51680 
                 ν d13  = 64.20 
               
               
                 r 24  = ∞ 
                 d 24  = 0.50 
               
               
                 r 25  = ∞ 
                 d 25  = 0.50 
                 n d14  = 1.51680 
                 ν d14  = 64.20 
               
               
                 r 26  = ∞ 
                 d 26  = 0.37 
               
               
                 r 27  = ∞(Imaging 
               
               
                 plane) 
               
               
                   
               
             
          
           
               
                 Aspherical Coefficients 
               
               
                   
               
             
          
           
               
                   
                 5th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −9.87397 × 10 −5   
               
               
                   
                 A 6  = 1.15328 × 10 −6   
               
               
                   
                 A 8  = −5.49135 × 10 −8   
               
               
                   
                 A 10  = 6.09563 × 10 −10   
               
               
                   
                 6th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −4.24242 × 10 −5   
               
               
                   
                 A 6  = 1.40352 × 10 −6   
               
               
                   
                 A 8  = −6.50420 × 10 −8   
               
               
                   
                 A 10  = 8.57412 × 10 −10   
               
               
                   
                 12th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −4.72028 × 10 −4   
               
               
                   
                 A 6  = −8.04768 × 10 −5   
               
               
                   
                 A 8  = 1.12791 × 10 −5   
               
               
                   
                 A 10  = −7.31468 × 10 −7   
               
               
                   
                 13th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −3.51794 × 10 −4   
               
               
                   
                 A 6  = −6.56639 × 10 −5   
               
               
                   
                 A 8  = 9.41874 × 10 −6   
               
               
                   
                 A 10  = −6.46097 × 10 −7   
               
               
                   
                 15th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −3.87575 × 10 −4   
               
               
                   
                 A 6  = −1.62934 × 10 −5   
               
               
                   
                 A 8  = 2.60691 × 10 −6   
               
               
                   
                 A 10  = −1.30886 × 10 −7   
               
               
                   
                   
               
             
          
           
               
                 Zooming Data (∞) 
               
             
          
           
               
                   
                   
                 WE 
                 ST 
                 TE 
               
               
                   
                   
               
               
                   
                 f (mm) 
                 5.07 
                 9.40 
                 17.40 
               
               
                   
                 F NO   
                 3.60 
                 4.30 
                 5.10 
               
               
                   
                 2ω (°) 
                 80.88 
                 44.45 
                 24.24 
               
               
                   
                 d 6   
                 0.60 
                 6.76 
                 10.79 
               
               
                   
                 d 11   
                 10.69 
                 4.53 
                 0.50 
               
               
                   
                 d 14   
                 6.15 
                 4.30 
                 2.05 
               
               
                   
                 d 17   
                 1.51 
                 3.36 
                 5.61 
               
               
                   
                   
               
             
          
         
       
     
       EXAMPLE 4 
       [0080]      
         [0000]    
       
         
               
               
               
               
             
               
             
               
               
             
               
             
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 r 1  = 61.265 
                 d 1  = 0.80 
                 n d1  = 2.00069 
                 ν d1  = 25.46 
               
               
                 r 2  = 10.388 
                 d 2  = 1.94 
               
               
                 r 3  = ∞ 
                 d 3  = 8.40 
                 n d2  = 1.90366 
                 ν d2  = 31.31 
               
               
                 r 4  = ∞ 
                 d 4  = 0.30 
               
               
                 r 5  = 16.191 (Aspheric) 
                 d 5  = 2.55 
                 n d3  = 1.82080 
                 ν d3  = 42.71 
               
               
                 r 6  = −23.992 (Aspheric) 
                 d 6  = (Variable) 
               
               
                 r 7  = 75.700 
                 d 7  = 0.50 
                 n d4  = 1.88300 
                 ν d4  = 40.76 
               
               
                 r 8  = 7.487 
                 d 8  = 1.13 
               
               
                 r 9  = −18.197 
                 d 9  = 0.45 
                 n d5  = 1.88300 
                 ν d5  = 40.76 
               
               
                 r 10  = 6.886 
                 d 10  = 1.22 
                 n d6  = 1.92286 
                 ν d6  = 20.88 
               
               
                 r 11  = 76.975 
                 d 11  = 
               
               
                   
                 (Variable) 
               
               
                 r 12  = 9.531 (Aspheric) 
                 d 12  = 1.53 
                 n d7  = 1.67790 
                 ν d7  = 55.34 
               
               
                 r 13  = −55.362 (Aspheric) 
                 d 13  = 1.00 
               
               
                 r 14  = ∞ (Stop) 
                 d 14  = 
               
               
                   
                 (Variable) 
               
               
                 r 15  = 8.917 (Aspheric) 
                 d 15  = 2.75 
                 n d8  = 1.62299 
                 ν d8  = 58.12 
               
               
                 r 16  = −6.211 
                 d 16  = 0.54 
                 n d9  = 1.92286 
                 ν d9  = 20.88 
               
               
                 r 17  = −11.293 
                 d 17  = 
               
               
                   
                 (Variable) 
               
               
                 r 18  = −22.013 
                 d 18  = 0.50 
                 n d10  = 2.00330 
                 ν d10  = 28.27 
               
               
                 r 19  = 4.213 
                 d 19  = 2.98 
                 n d11  = 1.64000 
                 ν d11  = 60.08 
               
               
                 r 20  = 11.057 
                 d 20  = 0.90 
               
               
                 r 21  = 12.761 
                 d 21  = 1.88 
                 n d12  = 1.84666 
                 ν d12  = 23.78 
               
               
                 r 22  = −47.501 
                 d 22  = 3.51 
               
               
                 r 23  = ∞ 
                 d 23  = 0.50 
                 n d13  = 1.51680 
                 ν d13  = 64.20 
               
               
                 r 24  = ∞ 
                 d 24  = 0.50 
               
               
                 r 25  = ∞ 
                 d 25  = 0.50 
                 n d14  = 1.51680 
                 ν d14  = 64.20 
               
               
                 r 26  = ∞ 
                 d 26  = 0.37 
               
               
                 r 27  = ∞ (Imaging plane) 
               
               
                   
               
             
          
           
               
                 Aspherical Coefficients 
               
               
                   
               
             
          
           
               
                   
                 5th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −8.96007 × 10 −5   
               
               
                   
                 A 6  = 9.20191 × 10 −8   
               
               
                   
                 A 8  = −9.46895 × 10 −9   
               
               
                   
                 A 10  = −3.43126 × 10 −10   
               
               
                   
                 6th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −4.66055 × 10 −5   
               
               
                   
                 A 6  = 3.45368 × 10 −7   
               
               
                   
                 A 8  = −2.10437 × 10 −8   
               
               
                   
                 A 10  = −4.70110 × 10 −11   
               
               
                   
                 12th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −2.50803 × 10 −4   
               
               
                   
                 A 6  = −3.40928 × 10 −5   
               
               
                   
                 A 8  = 6.25715 × 10 −6   
               
               
                   
                 A 10  = −4.27674 × 10 −7   
               
               
                   
                 13th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −1.00039 × 10 −4   
               
               
                   
                 A 6  = −2.55299 × 10 −5   
               
               
                   
                 A 8  = 5.64606 × 10 −6   
               
               
                   
                 A 10  = −4.33993 × 10 −7   
               
               
                   
                 15th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −3.48071 × 10 −4   
               
               
                   
                 A 6  = −4.87510 × 10 −6   
               
               
                   
                 A 8  = 1.54082 × 10 −6   
               
               
                   
                 A 10  = −9.89010 × 10 −8   
               
               
                   
                   
               
             
          
           
               
                 Zooming Data (∞) 
               
             
          
           
               
                   
                   
                 WE 
                 ST 
                 TE 
               
               
                   
                   
               
               
                   
                 f (mm) 
                 5.07 
                 9.40 
                 17.40 
               
               
                   
                 FNO 
                 3.60 
                 4.30 
                 5.00 
               
               
                   
                 2ω (°) 
                 80.56 
                 44.31 
                 24.24 
               
               
                   
                 d 6   
                 0.60 
                 6.46 
                 10.32 
               
               
                   
                 d 11   
                 10.22 
                 4.36 
                 0.50 
               
               
                   
                 d 14   
                 6.32 
                 4.36 
                 2.05 
               
               
                   
                 d 17   
                 1.51 
                 3.48 
                 5.78 
               
               
                   
                   
               
             
          
         
       
     
       EXAMPLE 5 
       [0081]      
         [0000]    
       
         
               
               
               
               
             
               
             
               
               
             
               
             
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 r 1  = 235.816 
                 d 1  = 0.80 
                 n d1  = 2.00069 
                 ν d1  = 25.46 
               
               
                 r 2  = 11.909 (Aspheric) 
                 d 2  = 0.10 
                 n d2  = 1.63494 
                 ν d2  = 23.22 
               
               
                 r 3  = 11.778 
                 d 3  = 1.84 
               
               
                 r 4  = ∞ 
                 d 4  = 8.40 
                 n d3  = 1.90366 
                 ν d3  = 31.31 
               
               
                 r 5  = ∞ 
                 d 5  = 0.30 
               
               
                 r 6  = 13.202 (Aspheric) 
                 d 6  = 2.61 
                 n d4  = 1.80139 
                 ν d4  = 45.45 
               
               
                 r 7  = −31.571 (Aspheric) 
                 d 7  = (Variable) 
               
               
                 r 8  = 262.366 
                 d 8  = 0.50 
                 n d5  = 1.88300 
                 ν d5  = 40.76 
               
               
                 r 9  = 7.420 
                 d 9  = 1.20 
               
               
                 r 10  = −14.068 
                 d 10  = 0.45 
                 n d6  = 1.88300 
                 ν d6  = 40.76 
               
               
                 r 11  = 8.001 
                 d 11  = 1.25 
                 n d7  = 1.92286 
                 ν d7  = 20.88 
               
               
                 r 12  = −83.756 
                 d 12  = 
               
               
                   
                 (Variable) 
               
               
                 r 13  = 9.090 (Aspheric) 
                 d 13  = 1.55 
                 n d8  = 1.67790 
                 ν d8  = 55.34 
               
               
                 r 14  = −82.610 (Aspheric) 
                 d 14  = 1.00 
               
               
                 r 15  = ∞ (Stop) 
                 d 15  = 
               
               
                   
                 (Variable) 
               
               
                 r 16  = 9.328 (Aspheric) 
                 d 16  = 2.65 
                 n d9  = 1.62299 
                 ν d9  = 58.12 
               
               
                 r 17  = −6.373 
                 d 17  = 0.54 
                 n d10  = 1.92286 
                 ν d10  = 20.88 
               
               
                 r 18  = −11.361 
                 d 18  = 
               
               
                   
                 (Variable) 
               
               
                 r 19  = −26.951 
                 d 19  = 0.50 
                 n d11  = 2.00330 
                 ν d11  = 28.27 
               
               
                 r 20  = 4.534 
                 d 20  = 3.37 
                 n d12  = 1.51633 
                 ν d12  = 64.14 
               
               
                 r 21  = 237.231 
                 d 21  = 0.93 
               
               
                 r 22  = 12.843 
                 d 22  = 1.79 
                 n d13  = 1.84666 
                 ν d13  = 23.78 
               
               
                 r 23  = 31.743 
                 d 23  = 3.19 
               
               
                 r 24  = ∞ 
                 d 24  = 0.50 
                 n d14  = 1.51680 
                 ν d14  = 64.20 
               
               
                 r 25  = ∞ 
                 d 25  = 0.50 
               
               
                 r 26  = ∞ 
                 d 26  = 0.50 
                 n d15  = 1.51680 
                 ν d15  = 64.20 
               
               
                 r 27  = ∞ 
                 d 27  = 0.37 
               
               
                 r 28  = ∞ (Imaging plane) 
               
               
                   
               
             
          
           
               
                 Aspherical Coefficients 
               
               
                   
               
             
          
           
               
                   
                 2nd surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −1.23512 × 10 −4   
               
               
                   
                 A 6  = −4.41841 × 10 −6   
               
               
                   
                 A 8  = 3.03797 × 10 −8   
               
               
                   
                 A 10  = 0 
               
               
                   
                 6th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −1.72818 × 10 −5   
               
               
                   
                 A 6  = −2.60801 × 10 −6   
               
               
                   
                 A 8  = 5.02193 × 10 −8   
               
               
                   
                 A 10  = −9.33953 × 10 −10   
               
               
                   
                 7th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = 7.80624 × 10 −5   
               
               
                   
                 A 6  = −2.76628 × 10 −6   
               
               
                   
                 A 8  = 5.81944 × 10 −8   
               
               
                   
                 A 10  = −9.20345 × 10 −10   
               
               
                   
                 13th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −9.93670 × 10 −5   
               
               
                   
                 A 6  = −7.03744 × 10 −5   
               
               
                   
                 A 8  = 1.45518 × 10 −5   
               
               
                   
                 A 10  = −8.56945 × 10 −7   
               
               
                   
                 14th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = 1.29919 × 10 −4   
               
               
                   
                 A 6  = −8.37340 × 10 −5   
               
               
                   
                 A 8  = 1.79486 × 10 −5   
               
               
                   
                 A 10  = −1.09991 × 10 −6   
               
               
                   
                 16th surface 
               
               
                   
                 K = 0.000 
               
               
                   
                 A 4  = −3.02414 × 10 −4   
               
               
                   
                 A 6  = −2.41845 × 10 −5   
               
               
                   
                 A 8  = 3.70554 × 10 −6   
               
               
                   
                 A 10  = −1.83040 × 10 −7   
               
               
                   
                   
               
             
          
           
               
                 Zooming Data (∞) 
               
             
          
           
               
                   
                   
                 WE 
                 ST 
                 TE 
               
               
                   
                   
               
               
                   
                 f (mm) 
                 5.07 
                 9.40 
                 17.40 
               
               
                   
                 FNO 
                 3.60 
                 4.20 
                 5.00 
               
               
                   
                 2ω (°) 
                 80.07 
                 43.89 
                 24.24 
               
               
                   
                 d 7   
                 0.60 
                 6.48 
                 10.46 
               
               
                   
                 d 12   
                 10.36 
                 4.48 
                 0.50 
               
               
                   
                 d 15   
                 6.08 
                 4.20 
                 2.05 
               
               
                   
                 d 18   
                 1.51 
                 3.39 
                 5.55 
               
               
                   
                   
               
             
          
         
       
     
         [0082]      FIGS. 6 ,  7 ,  8 ,  9  and  10  are aberration diagrams indicative of spherical aberration (SA), astigmatism (AS), distortion (DT) and chromatic aberration of magnification (CC) at the wide-angle ends (a), in intermediate states (b) and at the telephoto ends (c) of Examples 1, 2, 3, 4 and 5, respectively, upon focusing on an infinite object point. 
         [0083]    The values of conditions (1) to (4) in Examples 1, 2, 3, 4 and 5 are given below. 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Condition 
                   
               
             
          
           
               
                   
                   
                 (1) 
                 (2) 
                 (3) 
                 (4) 
               
               
                   
                   
               
             
          
           
               
                   
                 Ex. 1 
                 2.08 
                 1.21 
                 4.18 
                 2.44 
               
               
                   
                 Ex. 2 
                 2.03 
                 1.22 
                 3.9 
                 2.35 
               
               
                   
                 Ex. 3 
                 2.14 
                 1.22 
                 4.25 
                 2.41 
               
               
                   
                 Ex. 4 
                 2.39 
                 1.17 
                 3.96 
                 2.48 
               
               
                   
                 Ex. 5 
                 2.14 
                 1.18 
                 3.9 
                 2.47 
               
               
                   
                   
               
             
          
         
       
     
         [0084]    The zoom lens of the invention may have applications to imaging systems in which an object image formed through the image-formation optical system of the zoom lens is received at a CCD or silver-halide film for taking purposes, specifically a digital camera or digital terminal equipment such as a personal computer, a cellular phone or personal digital assistant (PDA), each having a camera incorporated in it, as embodied below. 
         [0085]      FIGS. 11 ,  12  and  13  are conceptual illustrations of a taking optical system  41  for digital cameras, in which the zoom les of the invention is incorporated.  FIG. 11  is a front perspective view of the appearance of a digital camera  40 , and  FIG. 12  is a rear perspective view of the same.  FIG. 13  is a sectional view of the construction of the digital camera  40 . In this embodiment, the digital camera  40  comprises a taking optical system  41  including a taking optical path  42 , a finder optical system  43  including a finder optical path  44 , a shutter  45 , a flash  46 , a liquid crystal monitor  47  and so on. As the shutter  45  mounted on the upper portion of the camera  40  is pressed down, it causes an image to be taken through the taking optical system  41 , for instance, the o zoom lens of Example 1. An object image formed by the taking optical system  41  is formed on the imaging plane of an imaging device  49  such as CCD or CMOS via a near infrared cut filter and an optical low-pass filter F. An object image received at the imaging device  49  such as CCD or CMOS is shown as an electronic image on the liquid crystal monitor (LCD)  47  via processing means  51 , which monitor is mounted on the back of the camera. This processing means  51  is connected with recording means (for instance, a memory)  52  in which the taken electronic image may be recorded. It is here noted that the recording means  52  may be provided separately from the processing means  51  or, alternatively, it may be constructed in such a way that images are electronically recorded and written therein by means of floppy discs, memory cards, MOs or the like. This camera could also be constructed in the form of a silver-halide camera using a silver-halide film in place of CCD  49 . 
         [0086]    Moreover, a finder objective optical system  53  is located on the finder optical path  44 . An object image formed by the finder objective optical system  53  is in turn formed on the field frame  57  of a Porro prism  55  that is an image-erecting member. In the rear of the Porro prism  55  there is an eyepiece optical system  59  located for guiding an erected image into the eyeball E of an observer. It is here noted that cover members  50  are provided on the entrance sides of the taking optical system  41  and finder objective optical system  53  as well as on the exit side of the eyepiece optical system  59 . 
         [0087]      FIG. 14  is a block diagram for the internal circuits of the main part of the aforesaid digital camera  40 . Reference is now made to  FIG. 14 . There is an imaging device  102  provided, in which color filters in a Bayer array are arranged on the front surface of photodiodes that define pixels. An imaging drive circuit  116  is activated in response to an order from a microcomputer (CPU)  113 . The imaging drive circuit  116  is built up of a CDS/AFC circuit comprising a CDS (correlated double sampling) for reducing a noise component and an AGC (automatic gain control) for stabilizing a signal level, and an A/D converter block for converting analog electric signals into digital electric signals. 
         [0088]    At the imaging device  102 , an object image formed via a zoom lens  101   a  and a focus lens  101   b  that form together a taking optical system is received at a photo-diode defined by each pixel. In the zoom lenses of Examples 1 to 5, it is noted that the fifth lens group G 5  of each zoom lens constitutes the focus lens  101   b ; however, other lens group may just as well be used as the focus lens  101   b . Then, photoelectric conversion is applied to the object image to produce the quantity of light to the CDS/AGC circuit  103  as the quantity of charges. The Bayer array here is a pixel array wherein lines each having R pixels and G (Gr) pixels alternately in the horizontal direction and lines each having G (Gr) pixels and B pixels alternately in the horizontal direction are lined up alternately in the vertical direction. It is noted that the imaging device  102  may operate in either a CMOS mode or a CCD mode. Although not illustrated, the imaging drive circuit  116  including a timing generator for driving the imaging device, CDS/AGC circuit  103  and A/D converter block  104  are each constructed of an AFE (analog front end circuit) IC device. 
         [0089]    Suppose here that the imaging device  102  can be driven in multiple modes at least involving a pixel addition read mode and a full pixel addition read mode. The pixel addition read mode is a drive mode adapted to read a plurality of adjacent pixels after the addition of their charges, while the full pixel addition read mode is a drive mode adapted to read all charges out of the effective pixels of the imaging device. 
         [0090]    The CDS (correlated double sampling)/AGC (auto gain control) circuit  103  applies waveform shaping to electric signals (analog image signals) read out of the imaging device  102  after reducing noises, etc., and further achieves high gain in such a way that the brightness of the image becomes the desired one. The A/D converter block  104  is adapted to convert the analog image signals pre-processed at the CDS/AGC circuit  103  into digital image signals (hereinafter called the image data). 
         [0091]    A bus  105  is a transfer path for transferring various data produced within the camera to the respective parts of the camera, and is connected to the A/D converter block  104 , SDRAM  106 , an image processor block  107 , a JPEG processor block  108 , a memory I/F  109 , an LCD driver  111  and a CPU  113 . The image data garnered at A/D converter block  104  is once stored in the SDRAM  104  via the bus  105 . The SDRAM  106  is adapted to temporarily store various data such as image data obtained at the A/D converter block  104 , and image data processed at the image processor block  107  and JPEG processor block  108 . 
         [0092]    At the image processor block  107 , the image data stored in the SDRAM  106  are read out to apply image processing to them. This image processor block  107  is constructed of a WB correction circuit  107   a , a synchronization circuit  107   b , a color transform/color reproduction circuit  107   c , a gamma transform circuit  107   d,  an edge extraction circuit  107   e , a noise reduction circuit  107   f  and an interpolation resizing circuit  107   b.    
         [0093]    The white balance (WB) correction circuit  107   a  multiplies R data and B data of the image data read out of the SDRAM  106  by white balance gain ordered from the CPU  113  to implement white balance correction. The synchronization circuit  107   b  generates from the image data produced out of the WB correction circuit  107   a  image data wherein three colors R, G and B constitute one pixel component. The color transform/color reproduction circuit  107   c  implements linear transform to multiply the image data produced out of the synchronization circuit  107   b  by a color matrix ordered from the CPU  113 , thereby correcting the image data for colors, and changing the tint of the image by calculation using a color saturation-hue coefficient. The gamma transform circuit  107   d  applies gamma transform (tone transform) processing to the image data produced out of the color transform/color reproduction circuit  107   c  so that the tone of the image data is corrected in such a way as to fit for displaying or printing. 
         [0094]    The edge extraction circuit  107   e  extracts the edge component of the image data using a BPF (band-pass filter) coefficient ordered from the CPU  113 . The noise reducing circuit  107   f  working as a block for extracting information about a flat portion and reducing noises applies filtering to the image data using a filter parameter ordered from the CPU  113 , thereby reducing noises in the image data. The interpolation resizing circuit  107   g  implements resizing for image data interpolation processing and for adjustment of output size as well. 
         [0095]    At such image processor block  107  as described above, the image data already subjected to image processing are again stored in the SDRAM  106 . 
         [0096]    The JPEG processor block  108  reads out of the SDRAM  106  the image data to which image processing has been applied to implement compression in the JPEG or other mode. The JPEG processor block  108  has also another function of reading the JPEG compressed image data to be recorded in the recording medium  110  and apply extension processing to them. The image data compressed at the JPEG processor block  108  are stored in the SDRAM  106 , and then recorded in the recording medium  110  via the memory I/F  109 . Not exclusively, the recording medium  110  comprises a memory card detachably attached to the camera body. 
         [0097]    The LDC driver  111  is to display an image on the LCD  112 . When the JPEG compressed image data recorded in the recording medium  110  are displayed, the JPEG compressed image data recorded in the recording medium  110  are read at the JPEG processor block  108 , and extension processing is then applied to them, after which they are once stored in the SDRAM  106 . The LCD driver  111  reads such image data out of the SDRAM  106  and converts them into image signals, which are then displayed on the LCD  112 . 
         [0098]    The CPU  113  working as a co-taking block and a noise reduction assessment block has centralized control over various sequences in the camera body. The CPU  113  is connected with an operating block  114  and a flash memory  115  having a camera program and focus lens position data loaded in it. The operating block  114  comprises a power button, a release button, various enter keys, etc. As the operating block  114  is operated by the user, it allows the CPU  113  to implement various sequences depending on the operation of the operating block  114 . The flash memory  115  is to store white balance gain, color matrix, and various parameters such as filter parameters. The CPU  113  reads from the flash memory  115  the parameters necessary for various sequences and issue orders to the respective processing blocks. A reference sensor  14  is to detect whether or not the focus lens  101   b  lies at a reference position. A temperature sensor  121  is to detect temperature and deliver the result of detection to the CPU  113 . 
         [0099]    The operating block  114  comprises buttons, switches, etc. for receiving various orders from the operator and delivering them to the CPU  113 . Although not illustrated, for instance, it comprises a release button for instructing when to start shooting, a focus mode switch button for selecting an AF (autofocus means) mode/MF (manual focus means):(modes), an MF drive button for selectively moving the focus lens  101   b  at the time of MF mode selection, a preset button for storing and instructing the position data about the focus lens  101   b , a preset value read button for reading and instructing the stored position data about the focus lens  101   b , an infinity button for instructing the focus lens  101   b  to move to a position corresponding to infinity depending on a zoom ratio, etc. 
         [0100]    The CPU  113  implements the camera program preloaded in the flash memory  115 , thereby controlling the overall operation of this electronic camera. For instance, it implements AF processing (contrast AF processing) or the like on the basis of the contrast of a subject image. 
         [0101]    A zoom motor  120  drives the zoom lens  101   a  via a zoom control block  118  comprising a drive circuit in response to an order from the CPU  113 , and a focus motor  119  drives the focus lens  101   b  via a focus control block  117  comprising a drive circuit in response to an order from the CPU  113 . It is here noted that the focus lens  101   b  is driven by the focus motor  110  in both the AF (autofocus) mode and the MF mode. 
         [0102]    The thus constructed digital camera  40  can be reduced in the overall size and thickness because the taking optical system  41  is a high-zoom-ratio, fast yet small-format arrangement with well corrected aberrations. 
         [0103]    In the embodiment of  FIG. 13 , a plane-parallel plate is located as the cover member  50 ; however, a powered lens may just as well be used.