Patent Publication Number: US-2023161141-A1

Title: Zoom optical system, optical apparatus and method for manufacturing the zoom optical system

Description:
TECHNICAL FIELD 
     The present invention relates to a zoom optical system, an optical apparatus using the zoom optical system, and a method for manufacturing the zoom optical system. 
     TECHNICAL BACKGROUND 
     Conventionally, a zoom optical system suitable for a photographic camera, an electronic still camera, a video camera, and the like has been proposed (for example, see Patent literature 1). The conventional zoom optical system has a problem that an angle of view is narrow in a wide angle end state and a variation of aberration is large upon zooming. 
     PRIOR ARTS LIST 
     Patent Document 
     
         
         Patent literature 1: Japanese Laid-Open Patent Publication No. 2015-166834 (A) 
       
    
     SUMMARY OF THE INVENTION 
     A zoom optical system (zoom lens) according to the present invention consists of a first lens group having negative refractive power, a second lens group having positive refractive power, and a rear lens group which are disposed in order from an object. In the zoom optical system, the rear lens group comprises a last lens group and an F lens group in order from a side closest to an image, lens groups forming the first lens group, the second lens group, and the rear lens group are configured in such a manner that, upon zooming, the respective lens groups move and a distance between the lens groups adjacent to each other changes, at least a part of the F lens group is configured to move upon focusing, and a following conditional expression is satisfied. 
       −0.220&lt; f 1/ fE&lt; 0.280
 
     where f1: a focal length of the first lens group, and 
     fE: a focal length of the last lens group. 
     An optical apparatus according to the present invention is configured such that the zoom optical system is mounted. 
     A method for manufacturing a zoom optical system according to the present invention is a method for manufacturing a zoom optical system consisting of a first lens group having negative refractive power, a second lens group having positive refractive power, and a rear lens group, which are disposed in order from an object, the method comprising disposing the first lens group, the second lens group, and the rear lens group in a barrel such that the rear lens group includes a last lens group and an F lens group in order from a side closest to an image, lens groups forming the first lens group, the second lens group, and the rear lens group are configured in such a manner that, upon zooming, the respective lens groups move and a distance between the lens groups adjacent to each other changes, at least apart of the F lens group is configured to move upon focusing, and a following conditional expression is satisfied. 
       −0.220&lt; f 1/ fE&lt; 0.280
 
     where f1: a focal length of the first lens group, and 
     fE: a focal length of the last lens group. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a cross-sectional view illustrating a lens configuration of a zoom lens according to Example 1 of the present embodiment; 
         FIGS.  2 A,  2 B, and  2 C  are various aberration graphs of the zoom lens according to Example 1 in a wide angle end state, an intermediate focal length state, and a telephoto end state, respectively; 
         FIG.  3    is a cross-sectional view illustrating a lens configuration of a zoom lens according to Example 2 of the present embodiment; 
         FIGS.  4 A,  4 B, and  4 C  are various aberration graphs of the zoom lens according to Example 2 in a wide angle end state, an intermediate focal length state, and a telephoto end state, respectively; 
         FIG.  5    is a cross-sectional view illustrating a lens configuration of a zoom lens according to Example 3 of the present embodiment; 
         FIGS.  6 A,  6 B, and  6 C  are various aberration graphs of the zoom lens according to Example 3 in a wide angle end state, an intermediate focal length state, and a telephoto end state, respectively; 
         FIG.  7    is a cross-sectional view illustrating a lens configuration of a zoom lens according to Example 4 of the present embodiment; 
         FIGS.  8 A,  8 B, and  8 C  are various aberration graphs of the zoom lens according to Example 4 in a wide angle end state, an intermediate focal length state, and a telephoto end state, respectively; 
         FIG.  9    is a cross-sectional view illustrating a lens configuration of a zoom lens according to Example 5 of the present embodiment; 
         FIGS.  10 A,  10 B, and  10 C  are various aberration graphs of the zoom lens according to Example 5 in a wide angle end state, an intermediate focal length state, and a telephoto end state, respectively; 
         FIG.  11    is a cross-sectional view illustrating a lens configuration of a zoom lens according to Example 6 of the present embodiment; 
         FIGS.  12 A,  12 B, and  12 C  are various aberration graphs of the zoom lens according to Example 6 in a wide angle end state, an intermediate focal length state, and a telephoto end state, respectively; 
         FIG.  13    is a schematic view illustrating a configuration of a camera including the zoom lens according to the present embodiment; and 
         FIG.  14    is a flowchart illustrating a method for manufacturing the zoom lens according to the present embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Embodiments will be described below with reference to the drawings. As an example of a zoom lens (zoom optical system) ZL according to the present embodiment, as illustrated in  FIG.  1   , a zoom lens ZL(1) consists of a first lens group G 1  having negative refractive power, a second lens group G 2  having positive refractive power, and a rear lens group GR which are disposed in order from an object. The rear lens group comprises a last lens group GE and an F lens group GF in order from a side closest to an image, lens groups forming the first lens group G 1 , the second lens group G 2 , and the rear lens group GR are configured in such a manner that, upon zooming, the respective lens groups move and a distance between the lens groups adjacent to each other changes, and at least a part of the F lens group GF is configured to move upon focusing, thereby performing focusing. The zoom lens ZL according to the present embodiment satisfies a following conditional expression (1) under such a configuration. 
       −0.220&lt; f 1/ fE&lt; 0.280  (1)
 
     where f1: a focal length of the first lens group G 1 , and 
     fE: a focal length of the last lens group GE. 
     The zoom lens ZL according to the present embodiment may be a zoom lens ZL(2) illustrated in  FIG.  3   , zoom lens ZL(3) illustrated in  FIG.  5   , a zoom lens ZL(4) illustrated in  FIG.  7   , a zoom lens ZL(5) illustrated in  FIG.  9   , or a zoom lens ZL(6) illustrated in  FIG.  11   . 
     The conditional expression (1) defines a ratio between the focal length f1 of the first lens group G 1  and the focal length fE of the last lens group GE. When the zoom lens ZL having the above-described configuration satisfies the conditional expression (1), a zoom lens (zoom optical system) can be achieved to have higher optical performance with a wide angle of view in the wide angle end state and reduction in variation of aberration upon zooming. 
     In the zoom lens ZL, even when the zoom lens has a value below a lower limit value of the conditional expression (1) (this means that the lower limit value is a negative value and the absolute value becomes larger) or a value exceeding an upper limit value (this means that the upper limit value is a positive value and the value becomes larger), it is difficult to obtain desired optical performance. This will be described in detail below. 
     Since the first lens group G 1  has the negative refractive power, when the last lens group GE has positive refractive power, the value of the formula “f1/fE” forming the conditional expression (1) becomes negative. When the value of the formula “f1/fE” is smaller than the lower limit value “−0.220” of the conditional expression (1) (when the absolute value is larger), the focal length of the first lens group G 1  needs to be made large, a diameter of the lens on the object side in the first lens group G 1  may become too large, and the whole length of the zoom lens ZL may become too long. Alternatively, the focal length of the last lens group GE needs to be made small, a coma aberration may be deteriorated, and the whole length of the zoom lens ZL may become too long. 
     To guarantee the effects of the conditional expression (1), the lower limit value is preferably set to be −0.210, and further preferably to be −0.200, −0.190, and −0.188. 
     On the other hand, when the last lens group GE has negative refractive power, the value of the formula “f1/fE” forming the conditional expression (1) becomes positive. Even when the value of the formula “f1/fE” is larger than the upper limit value “0.280” of the conditional expression (1), the focal length of the first lens group G 1  needs to be made large, a diameter of the lens on the object side in the first lens group G 1  may become too large, and the whole length of the zoom lens ZL may become too long. Alternatively, the focal length of the last lens group GE needs to be made small, a coma aberration may be deteriorated, and the whole length of the zoom lens ZL may become too long. 
     To guarantee the effects of the conditional expression (1), the upper limit value is preferably set to be 0.279, and further preferably to be 0.278, 0.250, and 0.200. 
     The zoom lens ZL according to the present embodiment preferably satisfies a following conditional expression (2). 
       −0.500&lt; f 1/ fF&lt; 0.700  (2)
 
     where fF: a focal length of the F lens group GF. 
     Since the first lens group G 1  has the negative refractive power, when the F lens group GF (a lens group having lenses that move upon focusing; a lens group adjacent to the object side of the last lens group GE.) has positive refractive power, the value of the formula “f1/fF” forming the conditional expression (2) becomes negative. When the value of the formula “f1/fF” is smaller than the lower limit value “−0.500” of the conditional expression (2) (when the absolute value is larger), the focal length of the first lens group G 1  needs to be made large, a diameter of the lens on the object side in the first lens group G 1  may become too large, and the whole length of the zoom lens ZL may become too long. Alternatively, the focal length of the focusing lens group GF needs to be made small, and a coma aberration may be deteriorated. 
     To guarantee the effects of the conditional expression (2), the lower limit value is preferably set to be −0.495, and further preferably to be −0.490, −0.485, −0.250, and 0.000. 
     On the other hand, when the focusing lens group GF has negative refractive power, the value of the formula “f1/fF” forming the conditional expression (2) becomes positive. Even when the value of the formula “f1/fF” is larger than the upper limit value “0.700” of the conditional expression (2), the focal length of the first lens group G 1  needs to be made large, a diameter of the lens on the object side in the first lens group G 1  may become too large, and the whole length of the zoom lens ZL may become too long. Alternatively, the focal length of the F lens group GF needs to be made small, and a coma aberration may be deteriorated. 
     To guarantee the effects of the conditional expression (2), the upper limit value is preferably set to be 0.650, and further preferably to be 0.630, 0.625, and 0.621. 
     The zoom lens ZL according to the present embodiment preferably satisfies a following conditional expression (3). 
       −1.500&lt; f 2/ fF&lt; 0.950  (3)
 
     where f2: a focal length of the second lens group G 2 . 
     Since the second lens group G 2  has the positive refractive power, when the F lens group GF has negative refractive power, the value of the formula “f2/fF” forming the conditional expression (3) becomes negative. When the value of the formula “f2/fF” is smaller than the lower limit value “−1.500” of the conditional expression (3) (when the absolute value is larger), the focal length of the second lens group G 2  needs to be made large, and a spherical aberration may be deteriorated. Alternatively, the focal length of the F lens group GF needs to be made small, and a coma aberration may be deteriorated. 
     To guarantee the effects of the conditional expression (3), the lower limit value is preferably set to be −1.400, and further preferably to be −1.350, −1.305, and −1.300. 
     On the other hand, when the F lens group GF has positive refractive power, the value of the formula “f2/fF” forming the conditional expression (3) becomes positive. Even when the value of the formula “f2/fF” is larger than the upper limit value “0.950” of the conditional expression (3), the focal length of the second lens group G 2  needs to be made large, and a spherical aberration may be deteriorated. Alternatively, the focal length of the F lens group GF needs to be made small, and a coma aberration may be deteriorated. 
     To guarantee the effects of the conditional expression (3), the upper limit value is preferably set to be 0.900, and further preferably to be 0.800, 0.730, 0.400, and 0.000. 
     The zoom lens ZL according to the present embodiment preferably satisfies a following conditional expression (4). 
       0.400&lt;− f 1/ f 2&lt;1.200  (4)
 
     The conditional expression (4) defines a condition relating to the ratio between the focal length of the first lens group G 1  and the focal length of the second lens group G 2 . Since the first lens group G 1  has the negative refractive power, the conditional expression (4) is set to a positive value as a minus value. When the value of the formula “−f1/f2” forming the conditional expression (4) is smaller than the lower limit value “0.400” of the conditional expression (4), the focal length of the first lens group G 1  needs to be made small, a spherical aberration may be deteriorated when the zoom lens is in a telephoto end state, and a coma aberration may be deteriorated when the zoom lens is in a wide angle end state. Alternatively, the focal length of the second lens group G 2  needs to be made large, a spherical aberration may be deteriorated. 
     To guarantee the effects of the conditional expression (4), the lower limit value is preferably set to be 0.420, and further preferably to be 0.440, 0.460, and 0.470. 
     On the other hand, When the value of the formula “−f1/f2” forming the conditional expression (4) is larger than the upper limit value “1.200” of the conditional expression (4), the focal length of the first lens group G 1  needs to be made large, a diameter of the lens on the object side in the first lens group G 1  may become too large, and the whole length of the zoom lens ZL may become too long. Alternatively, the focal length of the second lens group G 2  needs to be made small, a spherical aberration may be deteriorated. 
     To guarantee the effects of the conditional expression (4), the upper limit value is preferably set to be 1.150, and further preferably to be 1.120, 1.100, and 1.070. 
     In the zoom lens ZL according to the present embodiment, a lens forming the first lens group G 1  on a side closest to the object preferably has an aspherical surface. Thus, optical performance can be improved more accurately. 
     In the zoom lens ZL according to the present embodiment, a distance between the first lens group G 1  and the second lens group G 2  is preferably reduced upon zooming of at least a part of the lenses from a wide angle end state to a telephoto end state. Thus, desired optical performance is easily obtained. 
     In the zoom lens ZL according to the present embodiment, the second lens group G 2  and the last lens group GE preferably have a same movement path upon zooming of at least a part of the lenses from the wide angle end state to the telephoto end state. Thus, desired optical performance can be easily obtained, and the second lens group G 2  and the last lens group GE can be integrally moved for zooming, and therefore, a configuration of the movement control apparatus is simplified, which is preferable. 
     In the zoom lens ZL according to the present embodiment, a following conditional expression (5) is preferably satisfied. 
       1.000&lt; Bfw/fw&lt; 2.000  (5)
 
     where Bfw: back focus of the entire zoom lens in a wide angle end state, and 
     Fw: a focal length of the entire zoom lens in a wide angle end state. 
     The conditional expression (5) defines a condition relating to a ratio between the back focus and the focal length of the entire zoom lens in the wide angle end state. When the conditional expression (5) is satisfied, it is possible to achieve a small size and excellently correct various aberrations such as coma aberration, distortion, curvature of field, and spherical aberration while a wide angle of view is secured. 
     To guarantee the effects of the conditional expression (5), the upper limit value is preferably set to be 1.900, and further preferably to be 1.805, 1.700, and 1.650. 
     To guarantee the effects of the conditional expression (5), the lower limit value is preferably set to be 1.100, and further preferably to be 1.200, 1.300, and 1.400. 
     In the zoom lens ZL according to the present embodiment, a following conditional expression (6) is preferably satisfied. 
       0.100&lt;− f 1/ f 2 Rw&lt; 1.600  (6)
 
     where f2Rw: a composite focal length of the second lens group G 2  and the rear lens group GR in a wide angle end state. 
     The conditional expression (6) defines a condition relating to a ratio between the focal length of the first lens group G 1  and the composite focal length of the second lens group G 2  and the rear lens group GR. When the conditional expression (6) is satisfied, various aberrations including a coma aberration in the wide angle end state can be effectively corrected while a wide angle of view is secured, and fluctuation of various aberrations including a spherical aberration upon zooming can be prevented. 
     When the value of the zoom lens exceeds the upper limit value of the conditional expression (6), composite refractive power of the lens group behind the first lens group G 1  becomes strong in the wide angle end state, and various aberrations including a coma aberration in the wide angle end state is difficult to be effectively corrected. 
     When the value of the zoom lens falls below the lower limit value of the conditional expression (6), refractive power of the first lens group G 1  becomes strong, fluctuation of various aberrations including a spherical aberration is difficult to be prevented upon zooming from the wide angle end state to the telephoto end state. 
     To guarantee the effects of the conditional expression (6), the upper limit value is preferably set to be 1.400, and further preferably to be 1.200, 1.100, 1.000, and 0.900. 
     To guarantee the effects of the conditional expression (6), the lower limit value is preferably set to be 0.200, and further preferably to be 0.300, 0.400, and 0.500. 
     In the zoom lens ZL according to the present embodiment, a following conditional expression (7) is preferably satisfied. 
       −0.500&lt; f 1 /fFEw &lt;1.000  (7)
 
     where fFEw: a composite focal length of the F lens group GF and the last lens group GE in a wide angle end state. 
     The conditional expression (7) defines a condition relating to a ratio between the focal length of the first lens group G 1  and the composite focal length of the F lens group GF and the last lens group GE. When the conditional expression (7) is satisfied, various aberrations such as a coma aberration can be excellently corrected while a wide angle of view is secured. Further, preferably, the whole length of the zoom lens ZL does not become too long. 
     To guarantee the effects of the conditional expression (7), the upper limit value is preferably set to be 0.900, and further preferably to be 0.850, 0.800, and 0.750. 
     To guarantee the effects of the conditional expression (7), the lower limit value is preferably set to be −0.350, and further preferably to be −0.200, −0.100, and 0.000. 
     In the zoom lens ZL according to the present embodiment, a following conditional expression (8) is preferably satisfied. 
       −1.000&lt;− f 1/ fRw&lt; 0.600  (8)
 
     where fRw: a focal length of the rear lens group GR in a wide angle end state. 
     The conditional expression (8) defines a condition relating to a ratio between the focal length of the first lens group G 1  and the focal length of the rear lens group GR. When the conditional expression (8) is satisfied, various aberrations such as coma aberration, distortion, and curvature of field can be excellently corrected while a wide angle of view is secured, and fluctuation of various aberrations including a spherical aberration upon zooming can be prevented. 
     To guarantee the effects of the conditional expression (8), the upper limit value is preferably set to be 0.500, and further preferably to be 0.450, 0.420, and 0.400. 
     To guarantee the effects of the conditional expression (8), the lower limit value is preferably set to be −0.900, and further preferably to be −0.800, −0.720, −0.300, and 0.000. 
     In the zoom lens ZL according to the present embodiment, a following conditional expression (9) is preferably satisfied. 
       40.00°&lt;ω w&lt; 80.00°  (9)
 
     where ωw: a half angle of view in a wide angle end state. 
     The conditional expression (9) is a condition that defines an optimum value of the angle of view in the wide angle end state. When the conditional expression (9) is satisfied, various aberrations such as coma aberration, distortion, and curvature of field can be excellently corrected while a wide angle of view is secured. 
     To guarantee the effects of the conditional expression (9), the upper limit value is preferably set to be 75.00°, and further preferably to be 70.00°, 65.00°, and 62.00°. 
     To guarantee the effects of the conditional expression (9), the lower limit value is preferably set to be 43.50°, and further preferably to be 46.00°, 48.00°, 50.00°, 52.00°, and 54.00°. 
     In the zoom lens ZL according to the present embodiment, the rear lens group GR preferably includes a third lens group G 3  having positive refractive power, on a side closest to the object. Thus, optical performance can be improved more accurately. 
     According to the zoom lens ZL of the present embodiment having the above-described configuration, it is possible to achieve higher optical performance with a wide angle of view in the wide angle end state and reduction in variation of aberration upon zooming. 
     The optical apparatus of the present embodiment includes the zoom lens ZL having the above-described configuration. As a specific example, a camera (optical apparatus) including the zoom lens ZL will be described with reference to  FIG.  13   . As illustrated in  FIG.  13   , such a camera  1  is a digital camera including a zoom lens ZL as a photographing lens  2  according to the embodiment. In the camera  1 , light from an object (subject; not illustrated) is collected by the photographing lens  2 , and reaches an image sensor  3 . Thus, the image sensor  3  takes an image using the light from the subject, and the image is recorded in a memory (not illustrated) as a subject image. In this way, a photographer can capture an image of the subject with the camera  1 . The camera may be a mirrorless camera or a single-lens reflex camera having a quick return mirror. Although not illustrated, the camera  1  further includes an auxiliary light emitting unit that emits auxiliary light when a subject is dark, a function button used for setting various conditions of the digital camera and the like. 
     Herein, a compact type camera is illustrated as an example in which the camera  1  and the zoom lens ZL are integrally formed. However, the optical apparatus may also be a single-lens reflex camera in which a lens barrel including the zoom lens ZL and a camera body are detachable. 
     According to the camera  1  of the present embodiment having the configuration described above, the above-described zoom lens ZL serving as the photographing lens is mounted, and thus a camera with higher optical performance can be achieved in which an angle of view is wide in the wide angle end state and variation of aberration is reduced upon zooming. 
     Subsequently, a method for manufacturing the above-described zoom lens ZL will be described with reference to  FIG.  14   . First, a first lens group G 1  having negative refractive power, a second lens group G 2  having positive refractive power, and a rear lens group GR are disposed within a lens barrel in order from an object (step ST1). The first lens group G 1 , the second lens group G 2 , and the rear lens group GR are configured in such a manner that, upon zooming, the respective lens groups moves and a distance between the lens groups adjacent to each other changes (step ST2). Further, at least a part of F lens group GF is configured to move upon focusing (step ST3). Then, the respective lenses are disposed within a lens barrel to satisfy the conditional expression (1) described above (step ST4). 
     According to the manufacturing method of the present embodiment as described above, it is possible to manufacture the zoom lens ZL having good optical performance with a wide angle of view in the wide angle end state and reduction in variation of aberration upon zooming. 
     EXAMPLE 
     Zoom lenses ZL according to Examples of the present embodiment will be described with reference to the drawings.  FIGS.  1 ,  3 ,  5 ,  7 ,  9 , and  11    are cross-sectional views illustrating configurations of zoom lenses ZL {ZL(1) to ZL(6)} according to Examples 1 to 6, respectively. Each of the cross-sectional views illustrates positions of respective lens groups in a wide angle end state (W). In these drawings, arrows illustrated in the middle part indicate moving directions of the respective lens groups upon zooming (zooming operation) from the wide angle end state to the telephoto end state. In addition, an F lens group GF indicated as a focus by an arrow represents a lens group used entirely or partially for focusing, and an arrow indicates a moving direction of the F lens group GF at this time. Note that since the F lens group GF is entirely or partially used for focusing in this way, the F lens group GF is also referred to as a focusing lens group GF. 
     In these drawings, each of the lens groups is represented by a combination of a symbol G and a number, and each of the lenses is represented by a combination of a symbol L and a number. In this case, in order to prevent complications due to an increase in the types and numbers of symbols and numbers, the lens groups are represented using combinations of symbols and numbers independently for each Example. For this reason, although the combination of the same symbol and number is used for every Example, this indicates a configuration for every Example and does not means the same configuration. 
     Tables 1 to 6 are shown below, but are tables indicating data of Examples 1 to 6. 
     In “Lens Data” in tables, a surface number represents an order of an optical surface from the object side in a traveling direction of a light beam, R represents a radius of curvature of each optical surface (a surface where the center of curvature is located on the image side is a positive value), D represents a surface distance which is a distance between each optical surface and the next optical surface on the optical axis, vd represents Abbe number of the material of the optical member based on the d-line, and nd represents a refractive index of a material of an optical member with respect to the d-line (wavelength 587.6 nm). Furthermore, the surface number represents the order of the lens surface from the object side in the traveling direction of the light beam. The radius of curvature “a)” represents a plane or an aperture, and (stop S) represents the aperture stop S. The refractive index of air “nd=1.00000” is omitted. When the lens surface is an aspherical surface, the surface number is added with a mark * and the column of radius of curvature R indicates a paraxial radius of curvature. 
     In “Aspherical Surface Data” in tables, the shape of the aspherical surface indicated in “Lens Data” is represented by the following formula (a). X(y) represents a distance (zag amount) between the tangent plane at the vertex of the aspherical surface and a position on the aspherical surface at a height y in the optical axis direction, R represents a radius of curvature (paraxial radius of curvature) of a reference spherical surface, κ represents a conical coefficient, and Ai represents an i-th aspherical coefficient. “E-n” represents “×10 −n ”, for example, is 1.234E−05=1.234×10 −5 . A secondary aspherical coefficient A2 is 0, and thus is omitted. 
         X ( y )=( y   2   /R )/{1+(1−κ× y   2   /R   2 ) 1/2   }+A 4× y   4   +A 6× y   6   +A 8× y   8   +A 10× y   10   +A 12× y   12   (a)
 
     “General Data” in tables shows the data of the zoom lens, where f represents a focal length of the entire zoom lens, FNo represents an F number, ω represents a half angle of view (unit: °), and Y represents an image height at a wide angle end (wide), a middle position (middle), and a telephoto end (tele). 
     “Variable Distance Data” in tables indicates a distance to the next lens surface in the surface number denoted by symbols D1, D2, D3, and D4 as a distance to the next lens surface in the Table showing “Lens Data”. Bf represents a distance (back focus) from a lens last surface to an image surface I on the optical axis upon focusing on infinity. A whole length is a whole length of the zoom lens, and represents is a distance obtained by adding Bf to a distance the lens forefront surface to the lens last surface on the optical axis. The variable distance data indicate values at a wide angle end (wide), a middle position (middle), and a telephoto end (tele). 
     A Table of “Lens Group Data” indicates focal lengths of respective lens groups. In Table, f1 to f5 indicate focal lengths of first to fifth lens groups. 
     “Conditional Expression Corresponding Value” in tables indicates values corresponding to the conditional expressions (1) to (9) described above. 
     In all the data values, “mm” is generally used below as the unit of the focal length f, the radius of curvature R, the surface distance D, other lengths and the like, unless otherwise specified, but another unit can be used without being limited to the unit “mm” because an equivalent optical performance is acquired even when the optical system is proportionally expanded or reduced. 
     The description on the tables is common for all Examples, hence a duplicate description in respective Examples below will not be presented. 
     Example 1 
     Example 1 will be described with reference to  FIGS.  1  and  2    and Table 1.  FIG.  1    is a diagram illustrating a lens configuration of the zoom lens ZL(1) according to Example 1 of the present embodiment. The zoom lens ZL(1) includes a first lens group G 1  having negative refractive power, a second lens group G 2  having positive refractive power, a third lens group G 3  having positive refractive power, a fourth lens group G 4  having negative refractive power, and a fifth lens group G 5  having negative refractive power which are disposed in order from an object. A symbol (+) or (−) attached to each of the lens groups shows refractive power of each of the lens groups (the same applies to the following Examples). In this example, the third lens group G 3 , the fourth lens group G 4 , and the fifth lens group G 5  form a rear lens group GR. In the rear lens group GR, in order from a side closest to an image, the fifth lens group G 5  forms a last lens group GE, the fourth lens group G 4  forms an F lens group GF, and the fourth lens group G 4  (F lens group GF) forms a focusing lens group. 
     An aperture stop S, for determining brightness, is disposed on an image side of the second lens group G 2 . The aperture stop S is disposed independently of the second lens group G 2 , but moves in an optical axis direction together the second lens group G 2 . On an image side of the fifth lens group G 5 , an image surface I of a solid-state image sensor such as a CCD is located. 
     Upon zooming, the first to fifth lens groups G 1  to G 5  move in optical axis directions as indicated by arrows in  FIG.  1   , respectively. Distances between the respective lens groups caused by the movement, that is, distances to the next lens surface D1, D2, D3, and D4 shown in “Lens Data” of Table 1 are variable, and values of the distances are shown in a column of “Variable Distance Data”. 
     The first lens group G 1  consists of a negative meniscus lens L11 having a concave surface facing the image side, a negative meniscus lens L12 having a concave surface facing the image side, a biconcave negative lens L13, and a positive meniscus lens L14 having a concave surface facing the image side, which are disposed in order from an object. An image-side surface of the negative meniscus lens L11 and an image-side surface of the negative meniscus lens L12 are aspherical surfaces, respectively. 
     The second lens group G 2  consists of a positive meniscus lens L21 having a concave surface facing the image side and a cemented lens of a negative meniscus lens L22 having a concave surface facing the image side and a positive meniscus lens L23 having a concave surface facing the image side, which are disposed in order from an object. 
     The third lens group G 3  consists of a cemented lens of a negative meniscus lens L31 having a concave surface facing the image side and a positive meniscus lens L32 having a concave surface facing the image side, a biconvex positive lens L33, and a biconvex positive lens L34, which are disposed in order from an object. An image-side surface of the positive meniscus lens L32 is an aspherical surface. 
     The fourth lens group G 4  consists of a negative meniscus lens L41 having a concave surface facing an image side. The fifth lens group G 5  consists of a positive meniscus lens L51 having a convex surface facing an image side and a biconcave negative lens L52. The fourth lens group G 4 , the fifth lens group G 5 , and the third lens group G 3  are combined to form a rear lens group GR. An object-side surface of the negative lens L52 is an aspherical surface. 
     In the zoom lens ZL(1), focusing from infinity (long-distance object) to a short-distance object is performed when the fourth lens group G 4  is moved in a direction of the image surface. 
     As indicated by arrows in  FIG.  1   , the zoom lens ZL(1) according to Example 1 has a configuration in which the first lens group G 1  is moved toward the image side and the second to fifth lens groups G 2  to G 5  are moved toward the object side upon zooming from the wide angle end state to the telephoto end state. The aperture stop S moves integrally with the second lens group G 2  upon zooming. Upon zooming from the wide angle end state to the telephoto end state in this way, a distance between the first lens group G 1  and the second lens group G 2  is reduced. In addition, the second lens group G 2  and the fifth lens group G 5  have the same movement path upon zooming. 
     The following Table 1 lists values of data of the optical system according to Example 1. 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
             
            
               
                 [Lens Data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
               
               
                 Number 
                 R 
                 D 
                 νd 
                 nd 
               
               
                   
               
               
                 1 
                 190.7535 
                 3.000 
                 53.32 
                 1.69370 
               
               
                 *2 
                 18.8098 
                 9.500 
               
               
                 3 
                 51.5630 
                 2.900 
                 53.32 
                 1.69370 
               
               
                 *4 
                 22.7020 
                 9.700 
               
               
                 5 
                 −71.0651 
                 1.900 
                 82.57 
                 1.49782 
               
               
                 6 
                 44.4835 
                 0.100 
               
               
                 7 
                 32.6080 
                 4.500 
                 35.73 
                 1.90265 
               
               
                 8 
                 296.5863 
                 D1 
               
               
                 9 
                 63.0604 
                 2.000 
                 67.00 
                 1.59349 
               
               
                 10 
                 499.8755 
                 0.100 
               
               
                 11 
                 24.0057 
                 1.200 
                 40.66 
                 1.88300 
               
               
                 12 
                 13.3470 
                 4.500 
                 56.00 
                 1.56883 
               
               
                 13 
                 333.9818 
                 2.500 
               
            
           
           
               
               
               
               
               
            
               
                 14 
                 ∞ 
                 D2 
                 (Aperture Stop S) 
                   
               
            
           
           
               
               
               
               
               
            
               
                 15 
                 36.3784 
                 1.100 
                 46.59 
                 1.81600 
               
               
                 16 
                 14.0097 
                 4.710 
                 64.08 
                 1.51612 
               
               
                 *17 
                 61.0448 
                 0.200 
               
               
                 18 
                 27.9719 
                 3.150 
                 82.57 
                 1.49782 
               
               
                 19 
                 −75.3921 
                 0.250 
               
               
                 20 
                 91.9654 
                 3.050 
                 82.57 
                 1.49782 
               
               
                 21 
                 −29.3923 
                 D3 
               
               
                 22 
                 72.0930 
                 1.000 
                 45.31 
                 1.79500 
               
               
                 23 
                 20.9929 
                 D4 
               
               
                 24 
                 −538.2301 
                 4.800 
                 82.57 
                 1.49782 
               
               
                 25 
                 −20.1257 
                 0.100 
               
               
                 *26 
                 −38.9341 
                 1.400 
                 46.75 
                 1.76546 
               
               
                 27 
                 154.8320 
                 Bf 
               
               
                   
               
            
           
           
               
            
               
                 [Aspherical Surface Data] 
               
            
           
           
               
               
               
               
            
               
                 Aspherical Surface 
                 κ 
                 A4 
                 A6 
               
               
                   
               
               
                 2nd Surface 
                 −1.00000 
                 −1.33157E−05 
                 −3.07345E−08 
               
               
                 4th Surface 
                 −1.00000 
                  3.67009E−05 
                  1.37031E−07 
               
               
                 17th Surface 
                 0.00000 
                  1.75905E−05 
                 −6.64635E−08 
               
               
                 26th Surface 
                 −1.00000 
                 −2.67902E−05 
                 −3.34364E−08 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 Aspherical Surface 
                 A8 
                 A10 
                 A12 
               
               
                   
               
               
                 2nd Surface 
                  6.91260E−11 
                 −3.76684E−14 
                 — 
               
               
                 4th Surface 
                 −5.20756E−10 
                  3.14884E−12 
                 −5.61530E−15 
               
               
                 17th Surface 
                  2.26551E−10 
                 −4.40763E−12 
                 — 
               
               
                 26th Surface 
                 −1.13765E−10 
                 −1.88017E−13 
                 — 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 [General Data] 
               
               
                   
                   
               
               
                   
                 f = 14.420~20.000~29.101 
               
               
                   
                 FNO = 4.00~4.00~4.00 
               
               
                   
                 ω = 57.68°~46.85°~35.27° 
               
               
                   
                 Y = 21.70~21.70~21.70 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Variable Distance Data] 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 wide 
                 middle 
                 tele 
               
               
                   
                   
               
               
                   
                 D1 
                 28.616 
                 12.942 
                 2.214 
               
               
                   
                 D2 
                 7.483 
                 6.371 
                 3.521 
               
               
                   
                 D3 
                 1.579 
                 2.261 
                 2.007 
               
               
                   
                 D4 
                 5.766 
                 6.196 
                 9.300 
               
               
                   
                 Bf 
                 21.360 
                 26.809 
                 36.297 
               
               
                   
                 Entire Length 
                 126.464 
                 116.239 
                 114.999 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Lens Group Data] 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 f1 
                 −23.297 
               
               
                   
                 f2 
                 48.882 
               
               
                   
                 f3 
                 26.663 
               
               
                   
                 f4 
                 −37.580 
               
               
                   
                 f5 
                 −1392.883 
               
               
                   
                   
               
            
           
           
               
               
            
               
                   
                 [Conditional Expression Corresponding Value] 
               
               
                   
                   
               
               
                   
                 Conditional Expression(1) f1/fE = 0.017 
               
               
                   
                 Conditional Expression(2) f1/fF = 0.620 
               
               
                   
                 Conditional Expression(3) f2/fF = −1.301 
               
               
                   
                 Conditional Expression(4) −f1/f2 = 0.477 
               
               
                   
                 Conditional Expression(5) Bfw/fw = 1.481 
               
               
                   
                 Conditional Expression(6) −f1/f2Rw = 0.742 
               
               
                   
                 Conditional Expression(7) f1/fFEw = 0.643 
               
               
                   
                 Conditional Expression(8) −f1/fRw = 0.353 
               
               
                   
                 Conditional Expression(9) ωw = 57.68° 
               
               
                   
                   
               
            
           
         
       
     
     As shown in Table of “Conditional Expression Corresponding Value” described above, the zoom lens ZL(1) according to Example 1 illustrated in  FIG.  1    satisfies the conditional expressions (1) to (9) described above. 
       FIGS.  2 A,  2 B, and  2 C  are various aberration graphs (a spherical aberration graph, an astigmatism graph, a distortion graph, a coma aberration graph, and a chromatic aberration-of-magnification graph) of the zoom lens ZL(1) according to Example 1 in a wide angle end state, an intermediate focal length state, and a telephoto end state upon focusing on infinity. As can be seen from the various aberration graphs, the zoom lens ZL(1) according to Example 1 corrects various aberrations well from the wide angle end state to the telephoto end state, and has excellent imaging performance. Note that the distortion can be corrected by image processing after imaging, and optical correction is not required. 
     In  FIGS.  2 A,  2 B, and  2 C , FNO represents an F number, and ω represents a half angle of view (unit: °). Symbols d, g, C, and F represent aberrations on a d-line (wavelength 587.6 nm), a g-line (wavelength 435.8 nm), a C-line (wavelength 656.3 nm), and an F-line (wavelength 486.1 nm), respectively. In the spherical aberration graph, the astigmatism graph, and the coma aberration graph, a solid line indicates a sagittal image surface aberration, and a broken line indicates a meridional image surface aberration. A duplicate description will not be described below as in all aberration graphs of the following Examples. 
     Example 2 
     Example 2 will be described with reference to  FIGS.  3  and  4    and Table 2.  FIG.  3    is a diagram illustrating a lens configuration of the zoom lens ZL(2) according to Example 2 of the present embodiment. The zoom lens ZL(2) includes a first lens group G 1  having negative refractive power, a second lens group G 2  having positive refractive power, a third lens group G 3  having positive refractive power, a fourth lens group G 4  having negative refractive power, and a fifth lens group G 5  having positive refractive power which are disposed in order from an object. In this example, the third lens group G 3 , the fourth lens group G 4 , and the fifth lens group G 5  form a rear lens group GR. In the rear lens group GR, in order from a side closest to an image, the fifth lens group G 5  forms a last lens group GE, the fourth lens group G 4  forms an F lens group GF, and the fourth lens group G 4  (F lens group GF) forms a focusing lens group. 
     An aperture stop S, for determining brightness, is disposed on an image side of the second lens group G 2 . The aperture stop S is disposed independently of the second lens group G 2 , but moves in an optical axis direction together the second lens group G 2 . On an image side of the fifth lens group G 5 , an image surface I is located. 
     Upon zooming, the first to fifth lens groups G 1  to G 5  move in optical axis directions as indicated by arrows in  FIG.  3   , respectively. Distances between the respective lens groups caused by the movement, that is, distances to the next lens surface D1, D2, D3, and D4 shown in “Lens Data” of Table 2 are variable, and values of the distances are shown in a column of “Variable Distance Data”. 
     The first lens group G 1  consists of a negative meniscus lens L11 having a concave surface facing the image side, a negative meniscus lens L12 having a concave surface facing the image side, a biconcave negative lens L13, and a positive meniscus lens L14 having a concave surface facing the image side, which are disposed in order from an object. An image-side surface of the negative meniscus lens L11 and an image-side surface of the negative meniscus lens L12 are aspherical surfaces, respectively. 
     The second lens group G 2  consists of a biconvex positive lens L21 and a cemented lens of a negative meniscus lens L22 having a concave surface facing the image side and a biconvex positive lens L23, which are disposed in order from an object. 
     The third lens group G 3  consists of a cemented lens of a negative meniscus lens L31 having a concave surface facing the image side and a biconvex positive lens L32, a biconvex positive lens L33, and a biconvex positive lens L34, which are disposed in order from an object. An image-side surface of the biconvex positive lens L33 is an aspherical surface. 
     The fourth lens group G 4  consists of a negative meniscus lens L41 having a concave surface facing an image side. The fifth lens group G 5  consists of a positive meniscus lens L51 having a convex surface facing an image side. The fourth lens group G 4 , the fifth lens group G 5 , and the third lens group G 3  are combined to form a rear lens group GR. An image-side surface of the positive meniscus lens L51 is an aspherical surface. 
     In the zoom lens ZL(2), focusing from infinity (long-distance object) to a short-distance object is performed when the fourth lens group G 4  is moved in a direction of the image surface. 
     As indicated by arrows in  FIG.  3   , the zoom lens ZL(2) according to Example 2 has a configuration in which the first lens group G 1  is moved toward the image side and the second to fifth lens groups G 2  to G 5  are moved toward the object side upon zooming from the wide angle end state to the telephoto end state. The aperture stop S moves integrally with the second lens group G 2  upon zooming. Upon zooming from the wide angle end state to the telephoto end state in this way, a distance between the first lens group G 1  and the second lens group G 2  is reduced. In addition, the second lens group G 2  and the fifth lens group G 5  have the same movement path upon zooming. 
     The following Table 2 lists values of data of the optical system according to Example 2. 
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
             
            
               
                 [Lens Data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
               
               
                 Number 
                 R 
                 D 
                 νd 
                 nd 
               
               
                   
               
               
                 1 
                 105.12050 
                 3.000 
                 53.31 
                 1.69370 
               
               
                 *2 
                 14.14270 
                 7.068 
               
               
                 3 
                 35.00310 
                 2.955 
                 46.77 
                 1.76546 
               
               
                 *4 
                 23.32410 
                 7.971 
               
               
                 5 
                 −137.48910 
                 1.847 
                 46.50 
                 1.80420 
               
               
                 6 
                 56.85210 
                 0.100 
               
               
                 7 
                 33.72800 
                 5.000 
                 29.13 
                 2.00100 
               
               
                 8 
                 203.45350 
                 D1 
               
               
                 9 
                 54.10780 
                 3.000 
                 54.24 
                 1.53768 
               
               
                 10 
                 −96.44030 
                 0.100 
               
               
                 11 
                 32.33530 
                 1.500 
                 44.85 
                 1.74397 
               
               
                 12 
                 13.11780 
                 4.000 
                 58.10 
                 1.51225 
               
               
                 13 
                 −480.99880 
                 2.000 
               
            
           
           
               
               
               
               
               
            
               
                 14 
                 ∞ 
                 D2 
                 (Aperture Stop S) 
                   
               
            
           
           
               
               
               
               
               
            
               
                 15 
                 38.43600 
                 2.000 
                 40.66 
                 1.88300 
               
               
                 16 
                 15.38660 
                 3.500 
                 68.87 
                 1.49003 
               
               
                 17 
                 −200.15130 
                 0.000 
               
               
                 18 
                 52.69560 
                 3.000 
                 71.68 
                 1.55332 
               
               
                 *19 
                 −98.99660 
                 0.000 
               
               
                 20 
                 165.51060 
                 3.000 
                 82.57 
                 1.49782 
               
               
                 21 
                 −36.89330 
                 D3 
               
               
                 22 
                 620.18560 
                 1.500 
                 40.66 
                 1.88300 
               
               
                 23 
                 30.80350 
                 D4 
               
               
                 24 
                 −108.17020 
                 3.000 
                 70.35 
                 1.48743 
               
               
                 *25 
                 −36.57970 
                 Bf 
               
               
                   
               
            
           
           
               
            
               
                 [Aspherical Surface Data] 
               
            
           
           
               
               
               
               
            
               
                 Aspherical Surface 
                 κ 
                 A4 
                 A6 
               
               
                   
               
               
                 2nd Surface 
                 −1.00000 
                 −1.19107E−05 
                 1.69580E−08 
               
               
                 4th Surface 
                 −1.00000 
                  3.86364E−05 
                 4.04048E−08 
               
               
                 19th Surface 
                 0.00000 
                 −1.57314E−05 
                 −5.85331E−08  
               
               
                 25th Surface 
                 −1.00000 
                  2.59736E−05 
                 1.09567E−08 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 Aspherical Surface 
                 A8 
                 A10 
                 A12 
               
               
                   
               
               
                 2nd Surface 
                 −1.21696E−10 
                  2.63314E−13 
                 — 
               
               
                 4th Surface 
                  4.14632E−11 
                  1.08673E−12 
                 −3.50920E−15 
               
               
                 19th Surface 
                 −1.51543E−10 
                 −1.90250E−12 
                 — 
               
               
                 25th Surface 
                  4.63419E−10 
                 −1.35618E−12 
                 — 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 [General Data] 
               
               
                   
                   
               
               
                   
                 f = 14.430~20.010~29.110 
               
               
                   
                 FNO = 4.10~4.10~4.10 
               
               
                   
                 ω = 57.34°~47.36°~35.31° 
               
               
                   
                 Y = 21.70~21.70~21.70 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Variable Distance Data] 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 wide 
                 middle 
                 tele 
               
               
                   
                   
               
               
                   
                 D1 
                 28.929 
                 13.211 
                 1.599 
               
               
                   
                 D2 
                 12.659 
                 11.234 
                 8.667 
               
               
                   
                 D3 
                 2.011 
                 3.965 
                 6.046 
               
               
                   
                 D4 
                 3.914 
                 3.385 
                 3.871 
               
               
                   
                 Bf 
                 25.978 
                 31.499 
                 40.270 
               
               
                   
                 Entire Length 
                 128.032 
                 117.835 
                 114.994 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Lens Group Data] 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 f1 
                 −20.907 
               
               
                   
                 f2 
                 45.126 
               
               
                   
                 f3 
                 31.818 
               
               
                   
                 f4 
                 −36.752 
               
               
                   
                 f5 
                 111.855 
               
               
                   
                   
               
            
           
           
               
               
            
               
                   
                 [Conditional Expression Corresponding Value] 
               
               
                   
                   
               
               
                   
                 Conditional Expression(1) f1/fE = −0.187 
               
               
                   
                 Conditional Expression(2) f1/fF = 0.569 
               
               
                   
                 Conditional Expression(3) f2/fF = −1.228 
               
               
                   
                 Conditional Expression(4) −f1/f2 = 0.463 
               
               
                   
                 Conditional Expression(5) Bfw/fw = 1.800 
               
               
                   
                 Conditional Expression(6) −f1/f2Rw = 0.624 
               
               
                   
                 Conditional Expression(7) f1/fFEw = 0.347 
               
               
                   
                 Conditional Expression(8) −f1/fRw = 0.328 
               
               
                   
                 Conditional Expression(9) ωw = 57.34° 
               
               
                   
                   
               
            
           
         
       
     
     As shown in Table of “Conditional Expression Corresponding Value” described above, the zoom lens ZL(2) according to Example 2 illustrated in  FIG.  3    satisfies the conditional expressions (1) to (9) described above. 
       FIGS.  4 A,  4 B, and  4 C  are various aberration graphs (a spherical aberration graph, an astigmatism graph, a distortion graph, a coma aberration graph, and a chromatic aberration-of-magnification graph) of the zoom lens ZL(2) according to Example 2 in a wide angle end state, an intermediate focal length state, and a telephoto end state upon focusing on infinity. As can be seen from the various aberration graphs, the zoom lens ZL(2) according to Example 2 corrects various aberrations well from the wide angle end state to the telephoto end state, and has excellent imaging performance. 
     Example 3 
     Example 3 will be described with reference to  FIGS.  5  and  6    and Table 3.  FIG.  5    is a diagram illustrating a lens configuration of the zoom lens ZL(3) according to Example 3 of the present embodiment. The zoom lens ZL(3) includes a first lens group G 1  having negative refractive power, a second lens group G 2  having positive refractive power, a third lens group G 3  having positive refractive power, a fourth lens group G 4  having negative refractive power, and a fifth lens group G 5  having positive refractive power which are disposed in order from an object. In this example, the third lens group G 3 , the fourth lens group G 4 , and the fifth lens group G 5  form a rear lens group GR. In the rear lens group GR, in order from a side closest to an image, the fifth lens group G 5  forms a last lens group GE, the fourth lens group G 4  forms an F lens group GF, and the fourth lens group G 4  (F lens group GF) forms a focusing lens group. 
     An aperture stop S, for determining brightness, is disposed on an image side of the second lens group G 2 . The aperture stop S is disposed independently of the second lens group G 2 , but moves in an optical axis direction together the second lens group G 2 . On an image side of the fifth lens group G 5 , an image surface I is located. 
     Upon zooming, the first to fifth lens groups G 1  to G 5  move in optical axis directions as indicated by arrows in  FIG.  5   , respectively. Distances between the respective lens groups caused by the movement, that is, distances to the next lens surface D1, D2, D3, and D4 shown in “Lens Data” of Table 3 are variable, and values of the distances are shown in a column of “Variable Distance Data”. 
     The first lens group G 1  consists of a negative meniscus lens L11 having a concave surface facing the image side, a negative meniscus lens L12 having a concave surface facing the image side, a biconcave negative lens L13, and a biconvex positive lens L14, which are disposed in order from an object. An image-side surface of the negative meniscus lens L11 and an image-side surface of the negative meniscus lens L12 are aspherical surfaces, respectively. 
     The second lens group G 2  consists of a biconvex positive lens L21 and a cemented lens of a negative meniscus lens L22 having a concave surface facing the image side and a positive meniscus lens L23 having a concave surface facing the image side, which are disposed in order from an object. 
     The third lens group G 3  consists of a positive meniscus lens L31 having a concave surface facing the image side and a cemented lens of a negative meniscus lens L32 having a concave surface facing the image side and a biconvex positive lens L33, which are disposed in order from an object. An image-side surface of the biconvex positive lens L33 is an aspherical surface. 
     The fourth lens group G 4  consists of a biconcave negative lens L41. The fifth lens group G 5  consists of a cemented lens of a negative meniscus lens L51 having a concave surface facing an image side and a biconvex positive lens L52. The fourth lens group G 4 , the fifth lens group G 5 , and the third lens group G 3  are combined to form a rear lens group GR. An image-side surface of the biconvex positive lens L52 is an aspherical surface. 
     In the zoom lens ZL(3), focusing from infinity (long-distance object) to a short-distance object is performed when the fourth lens group G 4  is moved in a direction of the image surface. 
     As indicated by arrows in  FIG.  5   , the zoom lens ZL(3) according to Example 3 has a configuration in which the first lens group G 1  is moved toward the image side and the second to fifth lens groups G 2  to G 5  are moved toward the object side upon zooming from the wide angle end state to the telephoto end state. The aperture stop S moves integrally with the second lens group G 2  upon zooming. Upon zooming from the wide angle end state to the telephoto end state in this way, a distance between the first lens group G 1  and the second lens group G 2  is reduced. In addition, the second lens group G 2  and the fifth lens group G 5  have the same movement path upon zooming. 
     The following Table 3 lists values of data of the optical system according to Example 3. 
     
       
         
           
               
             
               
                 TABLE 3 
               
               
                   
               
             
            
               
                 [Lens Data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
               
               
                 Number 
                 R 
                 D 
                 νd 
                 nd 
               
               
                   
               
               
                 1 
                 152.68820 
                 3.000 
                 53.31 
                 1.69370 
               
               
                 *2 
                 15.55620 
                 8.357 
               
               
                 3 
                 38.53240 
                 2.955 
                 46.77 
                 1.76546 
               
               
                 *4 
                 26.42970 
                 8.354 
               
               
                 5 
                 −57.53130 
                 1.847 
                 46.50 
                 1.80420 
               
               
                 6 
                 93.52020 
                 0.100 
               
               
                 7 
                 49.33710 
                 5.000 
                 29.13 
                 2.00100 
               
               
                 8 
                 −175.05800 
                 D1 
               
               
                 9 
                 39.75280 
                 3.000 
                 82.57 
                 1.49782 
               
               
                 10 
                 −1718.80820 
                 0.100 
               
               
                 11 
                 25.06030 
                 1.500 
                 44.85 
                 1.74397 
               
               
                 12 
                 14.25220 
                 3.000 
                 62.67 
                 1.50163 
               
               
                 13 
                 133.78880 
                 2.000 
               
            
           
           
               
               
               
               
               
            
               
                 14 
                 ∞ 
                 D2 
                 (Aperture Stop S) 
                   
               
            
           
           
               
               
               
               
               
            
               
                 15 
                 27.62150 
                 2.000 
                 70.40 
                 1.48749 
               
               
                 16 
                 40.08290 
                 3.000 
               
               
                 17 
                 36.81870 
                 1.500 
                 44.85 
                 1.74397 
               
               
                 18 
                 12.66940 
                 3.500 
                 71.68 
                 1.55332 
               
               
                 *19 
                 −55.55510 
                 D3 
               
               
                 20 
                 −115.52620 
                 2.000 
                 40.66 
                 1.88300 
               
               
                 21 
                 172.71080 
                 D4 
               
               
                 22 
                 74.31210 
                 2.000 
                 45.57 
                 1.73496 
               
               
                 23 
                 17.17290 
                 7.000 
                 63.88 
                 1.51680 
               
               
                 *24 
                 −60.86760 
                 Bf 
               
               
                   
               
            
           
           
               
            
               
                 [Aspherical Surface Data] 
               
            
           
           
               
               
               
               
            
               
                 Aspherical Surface 
                 κ 
                 A4 
                 A6 
               
               
                   
               
               
                 2nd Surface 
                 −1.00000 
                 −3.02541E−06 
                 −3.52943E−08 
               
               
                 4th Surface 
                 −1.00000 
                  2.29497E−05 
                  6.39122E−08 
               
               
                 19th Surface 
                 0.00000 
                 −6.57962E−07 
                 −7.31304E−08 
               
               
                 24th Surface 
                 −1.00000 
                  1.46455E−05 
                  1.65839E−09 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 Aspherical Surface 
                 A8 
                 A10 
                 A12 
               
               
                   
               
               
                 2nd Surface 
                 3.90600E−11 
                 −7.28685E−15 
                 — 
               
               
                 4th Surface 
                 −4.07253E−11  
                  9.08597E−14 
                 6.7713E−16 
               
               
                 19th Surface 
                 5.86633E−10 
                 −9.34166E−12 
                 — 
               
               
                 24th Surface 
                 1.35320E−10 
                 −1.34392E−12 
                 — 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 [General Data] 
               
               
                   
                   
               
               
                   
                 f = 14.425~20.003~29.112 
               
               
                   
                 FNO = 4.10~4.10~4.10 
               
               
                   
                 ω = 57.87°~47.98°~35.78° 
               
               
                   
                 Y = 21.70~21.70~21.70 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Variable Distance Data] 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 wide 
                 middle 
                 tele 
               
               
                   
                   
               
               
                   
                 D1 
                 31.558 
                 16.828 
                 3.888 
               
               
                   
                 D2 
                 8.342 
                 3.928 
                 2.244 
               
               
                   
                 D3 
                 2.000 
                 2.000 
                 6.130 
               
               
                   
                 D4 
                 3.537 
                 7.950 
                 5.504 
               
               
                   
                 Bf 
                 22.847 
                 28.545 
                 37.016 
               
               
                   
                 Entire Length 
                 128.497 
                 119.464 
                 114.996 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Lens Group Data] 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 f1 
                 −22.803 
               
               
                   
                 f2 
                 44.561 
               
               
                   
                 f3 
                 49.665 
               
               
                   
                 f4 
                 −78.141 
               
               
                   
                 f5 
                 171.534 
               
               
                   
                   
               
            
           
           
               
               
            
               
                   
                 [Conditional Expression Corresponding Value] 
               
               
                   
                   
               
               
                   
                 Conditional Expression(1) f1/fE = −0.133 
               
               
                   
                 Conditional Expression(2) f1/fF = 0.292 
               
               
                   
                 Conditional Expression(3) f2/fF = −0.570 
               
               
                   
                 Conditional Expression(4) −f1/f2 = 0.512 
               
               
                   
                 Conditional Expression(5) Bfw/fw = 1.584 
               
               
                   
                 Conditional Expression(6) −f1/f2Rw = 0.682 
               
               
                   
                 Conditional Expression(7) f1/fFEw = 0.142 
               
               
                   
                 Conditional Expression(8) −f1/fRw = 0.310 
               
               
                   
                 Conditional Expression(9) ωw = 57.87° 
               
               
                   
                   
               
            
           
         
       
     
     As shown in Table of “Conditional Expression Corresponding Value” described above, the zoom lens ZL(3) according to Example 3 illustrated in  FIG.  5    satisfies the conditional expressions (1) to (9) described above. 
       FIGS.  6 A,  6 B, and  6 C  are various aberration graphs (a spherical aberration graph, an astigmatism graph, a distortion graph, a coma aberration graph, and a chromatic aberration-of-magnification graph) of the zoom lens ZL(3) according to Example 3 in a wide angle end state, an intermediate focal length state, and a telephoto end state upon focusing on infinity. As can be seen from the various aberration graphs, the zoom lens ZL(3) according to Example 3 corrects various aberrations well from the wide angle end state to the telephoto end state, and has excellent imaging performance. 
     Example 4 
     Example 4 will be described with reference to  FIGS.  7  and  8    and Table 4.  FIG.  7    is a diagram illustrating a lens configuration of the zoom lens ZL(4) according to Example 4 of the present embodiment. The zoom lens ZL(4) includes a first lens group G 1  having negative refractive power, a second lens group G 2  having positive refractive power, a third lens group G 3  having negative refractive power, and a fourth lens group G 4  having negative refractive power which are disposed in order from an object. In this example, the third lens group G 3  and the fourth lens group G 4  form a rear lens group GR. In the rear lens group GR, in order from a side closest to an image, the fourth lens group G 4  forms a last lens group GE, the third lens group G 3  forms an F lens group GF, and the third lens group G 3  (F lens group GF) forms a focusing lens group. 
     An aperture stop S is disposed inside the second lens group G 2 , and moves in an optical axis direction together the second lens group G 2 . On an image side of the fourth lens group G 4 , an image surface I is located. 
     Upon zooming, the first to fourth lens groups G 1  to G 4  move in optical axis directions as indicated by arrows in  FIG.  7   , respectively. Distances between the respective lens groups caused by the movement, that is, distances to the next lens surface D1, D2, and D3 shown in “Lens Data” of Table 4 are variable, and values of the distances are shown in a column of “Variable Distance Data”. 
     The first lens group G 1  consists of a negative meniscus lens L11 having a concave surface facing the image side, a negative meniscus lens L12 having a concave surface facing the image side, a biconcave negative lens L13, and a biconvex positive lens L14 which are disposed in order from an object. An image-side surface of the negative meniscus lens L11 and an image-side surface of the negative meniscus lens L12 are aspherical surfaces, respectively. 
     The second lens group G 2  consists of a positive meniscus lens L21 having a concave surface facing the image side, a cemented lens of a negative meniscus lens L22 having a concave surface facing the image side and a positive meniscus lens L23 having a concave surface facing the image side, and a biconvex positive lens L24 which are disposed in order from an object. 
     The third lens group G 3  consists of a negative meniscus lens L31 having a convex surface facing the image side. An image-side surface of the negative meniscus lens L31 is an aspherical surface. The third lens group G 3  forms a focusing lens group GF. 
     The fourth lens group G 4  consists of a biconvex positive lens L41 and a biconcave negative lens L42. The fourth lens group G 4  and the third lens group G 3  form a rear lens group GR. An object-side surface of the negative lens L42 is an aspherical surface. 
     In the zoom lens ZL(4), focusing from infinity (long-distance object) to a short-distance object is performed when the third lens group G 3  forming the focusing lens group GF is moved in a direction of the image surface. 
     As indicated by arrows in  FIG.  7   , the zoom lens ZL(4) according to Example 4 has a configuration in which the first lens group G 1  is moved toward the image side and the second to fourth lens groups G 2  to G 4  are moved toward the object side upon zooming from the wide angle end state to the telephoto end state. The aperture stop S moves integrally with the second lens group G 2  upon zooming. Upon zooming from the wide angle end state to the telephoto end state in this way, a distance between the first lens group G 1  and the second lens group G 2  is reduced. In addition, the second lens group G 2  and the fourth lens group G 4  have the same movement path upon zooming. 
     The following Table 4 lists values of data of the optical system according to Example 4. 
     
       
         
           
               
             
               
                 TABLE 4 
               
               
                   
               
             
            
               
                 [Lens Data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
               
               
                 Number 
                 R 
                 D 
                 νd 
                 nd 
               
               
                   
               
               
                 1 
                 143.42360 
                 1.847 
                 47.27 
                 1.77377 
               
               
                 *2 
                 19.73580 
                 7.301 
               
               
                 3 
                 40.25320 
                 2.955 
                 46.76 
                 1.76546 
               
               
                 *4 
                 22.69740 
                 9.439 
               
               
                 5 
                 −87.02160 
                 1.847 
                 40.66 
                 1.88300 
               
               
                 6 
                 64.64980 
                 0.100 
               
               
                 7 
                 37.85550 
                 6.000 
                 25.26 
                 1.90200 
               
               
                 8 
                 −193.93520 
                 D1 
               
               
                 9 
                 33.00090 
                 2.493 
                 36.96 
                 1.74776 
               
               
                 10 
                 116.22960 
                 0.100 
               
               
                 11 
                 28.47880 
                 2.025 
                 37.18 
                 1.83400 
               
               
                 12 
                 11.76190 
                 4.000 
                 82.57 
                 1.49782 
               
               
                 13 
                 194.58320 
                 2.000 
               
            
           
           
               
               
               
               
               
            
               
                 14 
                 ∞ 
                 5.968 
                 (Aperture Stop S) 
                   
               
            
           
           
               
               
               
               
               
            
               
                 15 
                 23.38410 
                 6.000 
                 82.57 
                 1.49782 
               
               
                 16 
                 −25.16850 
                 D2 
               
               
                 17 
                 −32.91040 
                 2.000 
                 47.26 
                 1.77377 
               
               
                 *18 
                 −479.55090 
                 D3 
               
               
                 19 
                 37.69510 
                 4.500 
                 82.57 
                 1.49782 
               
               
                 20 
                 −58.87610 
                 2.500 
               
               
                 *21 
                 −31.51450 
                 2.000 
                 40.17 
                 1.85135 
               
               
                 22 
                 610.49000 
                 Bf 
               
               
                   
               
            
           
           
               
            
               
                 [Aspherical Surface Data] 
               
            
           
           
               
               
               
               
            
               
                 Aspherical Surface 
                 κ 
                 A4 
                 A6 
               
               
                   
               
               
                 2nd Surface 
                 −1.33200 
                 −9.41293E−06 
                 −3.20026E−08 
               
               
                 4th Surface 
                 −7.50410 
                  1.06031E−04 
                 −2.03530E−07 
               
               
                 18th Surface 
                 0.00000 
                 −2.83335E−05 
                 −8.65856E−08 
               
               
                 21st Surface 
                 3.36500 
                 −6.30534E−05 
                 −2.78346E−07 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Aspherical Surface 
                 A8 
                 A10 
               
               
                   
                   
               
               
                   
                 2nd Surface 
                 8.15624E−11 
                 −5.06181E−14 
               
               
                   
                 4th Surface 
                 1.08502E−09 
                 −1.13123E−12 
               
               
                   
                 18th Surface 
                 −9.10000E−12  
                 −3.69900E−13 
               
               
                   
                 21st Surface 
                 5.71867E−10 
                 −1.54341E−11 
               
               
                   
                   
               
            
           
           
               
               
            
               
                   
                 [General Data] 
               
               
                   
                   
               
               
                   
                 f = 14.420~20.000~29.101 
               
               
                   
                 FNO = 4.10~4.10~4.10 
               
               
                   
                 ω = 57.95°~47.98°~35.90° 
               
               
                   
                 Y = 21.70~21.70~21.70 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Variable Distance Data] 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 wide 
                 middle 
                 tele 
               
               
                   
                   
               
               
                   
                 D1 
                 29.236 
                 15.205 
                 3.623 
               
               
                   
                 D2 
                 1.593 
                 2.038 
                 2.786 
               
               
                   
                 D3 
                 3.886 
                 3.441 
                 2.693 
               
               
                   
                 Bf 
                 21.267 
                 27.363 
                 36.916 
               
               
                   
                 Entire Length 
                 119.057 
                 111.123 
                 109.096 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Lens Group Data] 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 f1 
                 −23.718 
               
               
                   
                 f2 
                 22.703 
               
               
                   
                 f3 
                 −45.756 
               
               
                   
                 f4 
                 −224.939 
               
               
                   
                   
               
            
           
           
               
               
            
               
                   
                 [Conditional Expression Corresponding Value] 
               
               
                   
                   
               
               
                   
                 Conditional Expression(1) f1/fE = 0.105 
               
               
                   
                 Conditional Expression(2) f1/fF = 0.518 
               
               
                   
                 Conditional Expression(3) f2/fF = −0.496 
               
               
                   
                 Conditional Expression(4) −f1/f2 = 1.045 
               
               
                   
                 Conditional Expression(5) Bfw/fw = 1.475 
               
               
                   
                 Conditional Expression(6) −f1/f2Rw = 0.823 
               
               
                   
                 Conditional Expression(7) f1/fFEw = 0.703 
               
               
                   
                 Conditional Expression(8) −f1/fRw = −0.703 
               
               
                   
                 Conditional Expression(9) ωw = 57.95° 
               
               
                   
                   
               
            
           
         
       
     
     As shown in Table of “Conditional Expression Corresponding Value” described above, the zoom lens ZL(4) according to Example 4 illustrated in  FIG.  7    satisfies the conditional expressions (1) to (9) described above. 
       FIGS.  8 A,  8 B, and  8 C  are various aberration graphs (a spherical aberration graph, an astigmatism graph, a distortion graph, a coma aberration graph, and a chromatic aberration-of-magnification graph) of the zoom lens ZL(4) according to Example 4 in a wide angle end state, an intermediate focal length state, and a telephoto end state upon focusing on infinity. As can be seen from the various aberration graphs, the zoom lens ZL(4) according to Example 4 corrects various aberrations well from the wide angle end state to the telephoto end state, and has excellent imaging performance. 
     Example 5 
     Example 5 will be described with reference to  FIGS.  9  and  10    and Table 5.  FIG.  9    is a diagram illustrating a lens configuration of the zoom lens ZL(5) according to Example 5 of the present embodiment. The zoom lens ZL(5) includes a first lens group G 1  having negative refractive power, a second lens group G 2  having positive refractive power, a third lens group G 3  having positive refractive power, and a fourth lens group G 4  having negative refractive power which are disposed in order from an object. In this example, the third lens group G 3  and the fourth lens group G 4  form a rear lens group GR. In the rear lens group GR, in order from a side closest to an image, the fourth lens group G 4  forms a last lens group GE, the third lens group G 3  forms an F lens group GF, and the third lens group G 3  (F lens group GF) forms a focusing lens group. 
     An aperture stop S is disposed on an image side of the second lens group G 2 , and moves in an optical axis direction together the third lens group G 3 . On an image side of the fourth lens group G 4 , an image surface I is located. 
     Upon zooming, the first to fourth lens groups G 1  to G 4  move in optical axis directions as indicated by arrows in  FIG.  9   , respectively. Distances between the respective lens groups caused by the movement, that is, distances to the next lens surface D1, D2, and D3 shown in “Lens Data” of Table 5 are variable, and values of the distances are shown in a column of “Variable Distance Data”. 
     The first lens group G 1  consists of a negative meniscus lens L11 having a concave surface facing the image side, a negative meniscus lens L12 having a concave surface facing the image side, a biconcave negative lens L13, and a biconvex positive lens L14 which are disposed in order from an object. An image-side surface of the negative meniscus lens L11 and an image-side surface of the negative meniscus lens L12 are aspherical surfaces, respectively. 
     The second lens group G 2  consists of a positive meniscus lens L21 having a concave surface facing the image side and a cemented lens of a negative meniscus lens L22 having a concave surface facing the image side and a positive meniscus lens L23 having a concave surface facing the image side which are disposed in order from an object. 
     The third lens group G 3  consists of a biconvex positive lens L31 and a negative meniscus lens L32 having a convex surface facing the image side. An image-side surface of the negative meniscus lens L32 is an aspherical surface. 
     The fourth lens group G 4  consists of a cemented lens of a biconcave negative lens L41 and a biconvex positive lens L42. The fourth lens group G 4  and the third lens group G 3  form a rear lens group GR. An image-side surface of the biconvex positive lens L42 is an aspherical surface. 
     In the zoom lens ZL(5), focusing from infinity (long-distance object) to a short-distance object is performed when the third lens group G 3  is moved in a direction of the object surface. 
     As indicated by arrows in  FIG.  9   , the zoom lens ZL(5) according to Example 5 has a configuration in which the first lens group G 1  is moved toward the image side and the second to fourth lens groups G 2  to G 4  are moved toward the object side upon zooming from the wide angle end state to the telephoto end state. The aperture stop S moves integrally with the second lens group G 2  upon zooming. Upon zooming from the wide angle end state to the telephoto end state in this way, a distance between the first lens group G 1  and the second lens group G 2  is reduced. In addition, the second lens group G 2  and the fourth lens group G 4  have the same movement path upon zooming. 
     The following Table 5 lists values of data of the optical system according to Example 5. 
     
       
         
           
               
             
               
                 TABLE 5 
               
               
                   
               
             
            
               
                 [Lens Data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
               
               
                 Number 
                 R 
                 D 
                 νd 
                 nd 
               
               
                   
               
               
                 1 
                 93.21240 
                 1.847 
                 53.30 
                 1.69370 
               
               
                 *2 
                 13.52240 
                 5.931 
               
               
                 3 
                 29.89960 
                 2.955 
                 46.76 
                 1.76546 
               
               
                 *4 
                 20.20150 
                 9.371 
               
               
                 5 
                 −56.70350 
                 1.847 
                 44.85 
                 1.74397 
               
               
                 6 
                 78.54540 
                 0.100 
               
               
                 7 
                 38.64210 
                 8.000 
                 30.65 
                 1.69256 
               
               
                 8 
                 −69.11270 
                 D1 
               
               
                 9 
                 20.04870 
                 3.000 
                 82.57 
                 1.49782 
               
               
                 10 
                 72.62870 
                 0.100 
               
               
                 11 
                 27.61350 
                 1.500 
                 44.85 
                 1.74397 
               
               
                 12 
                 10.84710 
                 5.500 
                 55.25 
                 1.52004 
               
               
                 13 
                 593.20040 
                 2.000 
               
            
           
           
               
               
               
               
               
            
               
                 14 
                 ∞ 
                 D2 
                 (Aperture Stop S) 
                   
               
            
           
           
               
               
               
               
               
            
               
                 15 
                 25.23910 
                 6.000 
                 82.57 
                 1.49782 
               
               
                 16 
                 −20.00280 
                 0.100 
               
               
                 17 
                 −35.40880 
                 2.000 
                 40.17 
                 1.85135 
               
               
                 *18 
                 −716.06180 
                 D3 
               
               
                 19 
                 −69.18060 
                 2.000 
                 44.91 
                 1.74319 
               
               
                 20 
                 16.99120 
                 9.000 
                 63.88 
                 1.51680 
               
               
                 *21 
                 −50.41600 
                 Bf 
               
               
                   
               
            
           
           
               
            
               
                 [Aspherical Surface Data] 
               
            
           
           
               
               
               
               
            
               
                 Aspherical Surface 
                 κ 
                 A4 
                 A6 
               
               
                   
               
               
                 2nd Surface 
                 −1.00000 
                 1.38355E−06 
                 2.07620E−08 
               
               
                 4th Surface 
                 −1.00000 
                 3.59847E−05 
                 2.08880E−08 
               
               
                 18th Surface 
                 −1.00000 
                 2.70717E−05 
                 3.79198E−08 
               
               
                 21st Surface 
                 −1.00000 
                 1.19458E−05 
                 6.17241E−08 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 Aspherical Surface 
                 A8 
                 A10 
                 A12 
               
               
                   
               
               
                 2nd Surface 
                 −1.89816E−10 
                 5.02341E−13 
                 — 
               
               
                 4th Surface 
                  4.46280E−10 
                 −1.00580E−12  
                 1.42060E−17 
               
               
                 18th Surface 
                  3.60945E−10 
                 1.44176E−12 
                 — 
               
               
                 21st Surface 
                 −3.96485E−10 
                 3.16643E−13 
                 — 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 [General Data] 
               
               
                   
                   
               
               
                   
                 f = 14.420~20.000~29.100 
               
               
                   
                 FNO = 4.10~4.10~4.10 
               
               
                   
                 ω = 58.12°~48.25°~36.38° 
               
               
                   
                 Y = 21.70~21.70~21.70 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Variable Distance Data] 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 wide 
                 middle 
                 tele 
               
               
                   
                   
               
               
                   
                 D1 
                 27.410 
                 13.108 
                 1.500 
               
               
                   
                 D2 
                 7.612 
                 6.891 
                 5.627 
               
               
                   
                 D3 
                 4.000 
                 4.721 
                 5.985 
               
               
                   
                 Bf 
                 21.168 
                 28.042 
                 38.588 
               
               
                   
                 Entire Length 
                 121.440 
                 114.013 
                 112.952 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Lens Group Data] 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 f1 
                 −22.394 
               
               
                   
                 f2 
                 41.067 
               
               
                   
                 f3 
                 46.152 
               
               
                   
                 f4 
                 −80.774 
               
               
                   
                   
               
            
           
           
               
               
            
               
                   
                 [Conditional Expression Corresponding Value] 
               
               
                   
                   
               
               
                   
                 Conditional Expression(1) f1/fE = 0.277 
               
               
                   
                 Conditional Expression(2) f1/fF = −0.485 
               
               
                   
                 Conditional Expression(3) f2/fF = 0.890 
               
               
                   
                 Conditional Expression(4) −f1/f2 = 0.545 
               
               
                   
                 Conditional Expression(5) Bfw/fw = 1.468 
               
               
                   
                 Conditional Expression(6) −f1/f2Rw = 0.708 
               
               
                   
                 Conditional Expression(7) f1/fFEw = −0.233 
               
               
                   
                 Conditional Expression(8) −f1/fRw = 0.233 
               
               
                   
                 Conditional Expression(9) ωw = 58.12° 
               
               
                   
                   
               
            
           
         
       
     
     As shown in Table of “Conditional Expression Corresponding Value” described above, the zoom lens ZL(5) according to Example 5 illustrated in  FIG.  9    satisfies the conditional expressions (1) to (9) described above. 
       FIGS.  10 A,  10 B, and  10 C  are various aberration graphs (a spherical aberration graph, an astigmatism graph, a distortion graph, a coma aberration graph, and a chromatic aberration-of-magnification graph) of the zoom lens ZL(5) according to Example 5 in a wide angle end state, an intermediate focal length state, and a telephoto end state upon focusing on infinity. As can be seen from the various aberration graphs, the zoom lens ZL(5) according to Example 5 corrects various aberrations well from the wide angle end state to the telephoto end state, and has excellent imaging performance. 
     Example 6 
     Example 6 will be described with reference to  FIGS.  11  and  12    and Table 6.  FIG.  11    is a diagram illustrating a lens configuration of the zoom lens ZL(6) according to Example 6 of the present embodiment. The zoom lens ZL(6) includes a first lens group G 1  having negative refractive power, a second lens group G 2  having positive refractive power, a third lens group G 3  having positive refractive power, and a fourth lens group G 4  having negative refractive power which are disposed in order from an object. In this example, the third lens group G 3  and the fourth lens group G 4  form a rear lens group GR. In the rear lens group GR, in order from a side closest to an image, the fourth lens group G 4  forms a last lens group GE, the third lens group G 3  forms an F lens group GF, and a lens L35 on a side closest to the image of the third lens group G 3  (F lens group GF) forms a focusing lens group. 
     An aperture stop S, for determining brightness, is disposed on an image side of the second lens group G 2 . The aperture stop S is disposed independently of the second lens group G 2 , but moves in an optical axis direction together the second lens group G 2 . On an image side of the fourth lens group G 4 , an image surface I is located. 
     Upon zooming, the first to fourth lens groups G 1  to G 4  move in optical axis directions as indicated by arrows in  FIG.  11   , respectively. Distances between the respective lens groups caused by the movement, that is, distances to the next lens surface D1, D2, and D3 shown in “Lens Data” of Table 6 are variable, and values of the distances are shown in a column of “Variable Distance Data”. 
     The first lens group G 1  consists of a negative meniscus lens L11 having a concave surface facing the image side, a negative meniscus lens L12 having a concave surface facing the image side, a biconcave negative lens L13, and a positive meniscus lens L14 having a concave surface facing the image side which are disposed in order from an object. An image-side surface of the negative meniscus lens L11 and an image-side surface of the negative meniscus lens L12 are aspherical surfaces, respectively. 
     The second lens group G 2  consists of a biconvex positive lens L21 and a cemented lens of a negative meniscus lens L22 having a concave surface facing the image side and a positive meniscus lens L23 having a concave surface facing the image side which are disposed in order from an object. 
     The third lens group G 3  consists of a cemented lens of a negative meniscus lens L31 having a concave surface facing the image side and a positive meniscus lens L32 having a concave surface facing the image side, a biconvex positive lens L33, a biconvex positive lens L34, and a negative meniscus lens L35 having a concave surface facing the image side which are disposed in order from an object. An image-side surface of the positive meniscus lens L32 is an aspherical surface. 
     The fourth lens group G 4  consists of a positive meniscus lens L41 having a convex surface facing the image side and a biconcave negative lens L42. The fourth lens group G 4  and the third lens group G 3  are combined to form a rear lens group GR. An object-side surface of the negative lens L42 is an aspherical surface. 
     In the zoom lens ZL(6), focusing from infinity (long-distance object) to a short-distance object is performed when the lens L35 on a side closest to the image of the third lens group G 3  is moved in a direction of the image surface. 
     As indicated by arrows in  FIG.  11   , the zoom lens ZL(6) according to Example 6 has a configuration in which the first lens group G 1  is moved toward the image side and the second to fourth lens groups G 2  to G 4  are moved toward the object side upon zooming from the wide angle end state to the telephoto end state. The aperture stop S moves integrally with the second lens group G 2  upon zooming. Upon zooming from the wide angle end state to the telephoto end state in this way, a distance between the first lens group G 1  and the second lens group G 2  is reduced. In addition, the second lens group G 2  and the fourth lens group G 4  have the same movement path upon zooming. 
     The following Table 6 lists values of data of the optical system according to Example 6. 
     
       
         
           
               
             
               
                 TABLE 6 
               
               
                   
               
             
            
               
                 [Lens Data] 
               
            
           
           
               
               
               
               
               
            
               
                 Surface 
                   
                   
                   
                   
               
               
                 Number 
                 R 
                 D 
                 νd 
                 nd 
               
               
                   
               
               
                 1 
                 59.8522 
                 3.000 
                 53.32 
                 1.69370 
               
               
                 *2 
                 20.0478 
                 9.500 
               
               
                 3 
                 114.7269 
                 2.900 
                 53.32 
                 1.69370 
               
               
                 *4 
                 22.1986 
                 11.955 
               
               
                 5 
                 −224.8102 
                 1.900 
                 82.57 
                 1.49782 
               
               
                 6 
                 31.3956 
                 0.665 
               
               
                 7 
                 29.3038 
                 4.500 
                 35.73 
                 1.90265 
               
               
                 8 
                 98.7168 
                 D1 
               
               
                 9 
                 331.6158 
                 2.000 
                 67.00 
                 1.59349 
               
               
                 10 
                 −82.5907 
                 1.205 
               
               
                 11 
                 22.2836 
                 1.200 
                 40.66 
                 1.88300 
               
               
                 12 
                 12.6519 
                 4.500 
                 56.00 
                 1.56883 
               
               
                 13 
                 163.3779 
                 2.500 
               
            
           
           
               
               
               
               
               
            
               
                 14 
                 ∞ 
                 D2 
                 (Aperture Stop S) 
                   
               
            
           
           
               
               
               
               
               
            
               
                 15 
                 27.8092 
                 1.100 
                 46.59 
                 1.81600 
               
               
                 16 
                 12.6205 
                 4.710 
                 64.08 
                 1.51612 
               
               
                 *17 
                 59.9800 
                 0.200 
               
               
                 18 
                 34.7740 
                 3.150 
                 82.57 
                 1.49782 
               
               
                 19 
                 −41.7717 
                 0.250 
               
               
                 20 
                 76.1603 
                 3.050 
                 82.57 
                 1.49782 
               
               
                 21 
                 −41.4669 
                 1.115 
               
               
                 22 
                 158.9131 
                 1.000 
                 45.31 
                 1.79500 
               
               
                 23 
                 25.4250 
                 D3 
               
               
                 24 
                 −179.2003 
                 3.000 
                 82.57 
                 1.49782 
               
               
                 25 
                 −29.1129 
                 1.000 
               
               
                 *26 
                 −44.2756 
                 1.400 
                 46.75 
                 1.76546 
               
               
                 27 
                 333.0581 
                 Bf 
               
               
                   
               
            
           
           
               
            
               
                 [Aspherical Surface Data] 
               
            
           
           
               
               
               
               
            
               
                 Aspherical Surface 
                 κ 
                 A4 
                 A6 
               
               
                   
               
               
                 2nd Surface 
                 −1.00000 
                 −5.37297E−06 
                 −2.45009E−08 
               
               
                 4th Surface 
                 −1.00000 
                  3.94361E−05 
                  1.22579E−07 
               
               
                 17th Surface 
                 0.00000 
                 −4.54651E−07 
                 −1.25750E−07 
               
               
                 26th Surface 
                 −1.00000 
                 −2.29913E−05 
                 −3.91709E−08 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 Aspherical Surface 
                 A8 
                 A10 
                 A12 
               
               
                   
               
               
                 2nd Surface 
                  3.23042E−11 
                 −4.78483E−15 
                 — 
               
               
                 4th Surface 
                 −5.49173E−10 
                  3.15773E−12 
                 −5.51800E−15 
               
               
                 17th Surface 
                  2.28790E−10 
                 −9.64769E−12 
                 — 
               
               
                 26th Surface 
                 −5.02820E−11 
                 −2.37742E−13 
                 — 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 [General Data] 
               
               
                   
                   
               
               
                   
                 f = 14.430~20.010~29.110 
               
               
                   
                 FNO = 4.00~4.00~4.00 
               
               
                   
                 ω = 57.66°~46.96°~35.32° 
               
               
                   
                 Y = 21.07~21.70~21.70 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Variable Distance Data] 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 wide 
                 middle 
                 tele 
               
               
                   
                   
               
               
                   
                 D1 
                 25.911 
                 12.633 
                 2.346 
               
               
                   
                 D2 
                 8.768 
                 6.786 
                 4.521 
               
               
                   
                 D3 
                 3.925 
                 5.907 
                 8.171 
               
               
                   
                 Bf 
                 21.438 
                 27.017 
                 36.366 
               
               
                   
                 Entire Length 
                 125.841 
                 118.142 
                 117.203 
               
               
                   
                   
               
            
           
           
               
            
               
                 [Lens Group Data] 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 f1 
                 −22.037 
               
               
                   
                 f2 
                 47.094 
               
               
                   
                 f3 
                 54.811 
               
               
                   
                 f4 
                 −199.936 
               
               
                   
                   
               
            
           
           
               
               
            
               
                   
                 [Conditional Expression Corresponding Value] 
               
               
                   
                   
               
               
                   
                 Conditional Expression(1) f1/fE = 0.110 
               
               
                   
                 Conditional Expression(2) f1/fF = −0.402 
               
               
                   
                 Conditional Expression(3) f2/fF = 0.859 
               
               
                   
                 Conditional Expression(4) −f1/f2 = 0.468 
               
               
                   
                 Conditional Expression(5) Bfw/fw = 1.486 
               
               
                   
                 Conditional Expression(6) −f1/f2Rw = 0.739 
               
               
                   
                 Conditional Expression(7) f1/fFEw = −0.331 
               
               
                   
                 Conditional Expression(8) −f1/fRw = 0.331 
               
               
                   
                 Conditional Expression(9) ωw = 57.66° 
               
               
                   
                   
               
            
           
         
       
     
     As shown in Table of “Conditional Expression Corresponding Value” described above, the zoom lens ZL(6) according to Example 6 illustrated in  FIG.  11    satisfies the conditional expressions (1) to (9) described above. 
       FIGS.  12 A,  12 B, and  12 C  are various aberration graphs (a spherical aberration graph, an astigmatism graph, a distortion graph, a coma aberration graph, and a chromatic aberration-of-magnification graph) of the zoom lens ZL(6) according to Example 6 in a wide angle end state, an intermediate focal length state, and a telephoto end state upon focusing on infinity. As can be seen from the various aberration graphs, the zoom lens ZL(6) according to Example 6 corrects various aberrations well from the wide angle end state to the telephoto end state, and has excellent imaging performance. 
     Each of Examples described above indicates one specific example of the present invention, and the present invention is not limited to these Examples. 
     The following contents can be appropriately employed within the range without impairing the optical performance of the zoom lens according to the present embodiment. 
     The configuration with the five groups or four groups are described as an example of the configuration of the zoom lens according to the present embodiments, but the present invention is not limited thereto. The present invention can be applied to a configuration of a zoom lens with other number of groups (for example, six groups or the like). More specifically, a configuration may be used in which a lens or a lens group is added to the zoom lens of the present embodiments on a side closest to an object or on a side closest to the image surface. The lens group is a portion including at least one lens separated from another lens with an air distance that varies upon zooming. 
     The zoom lens of the embodiments may be a focusing lens group in which the single or plurality of lens groups or part of lens groups are moved in the optical axis direction to perform focusing from the infinity distant object to the short-distance object. The focusing lens group can also be applied to autofocus, and can also be suitable for driving a motor for autofocus (using an ultrasonic motor or the like). 
     The zoom lens of the embodiments may be a vibration proof lens group in which the lens groups or part of lens groups are moved to have a component in a direction perpendicular to the optical axis or rotated (swing) in an in-plane direction including the optical axis to correct image blur caused by camera shake. At least a part of lenses in the lens group between the first lens group and the focusing lens group is preferably a vibration proof lens (vibration proof lens group). 
     The lens surface may be formed to have a spherical surface or a planer surface, or may be formed to have an aspherical shape. When the lens surface is a spherical surface or a planer surface, lens processing and assembly adjustment are facilitated and deterioration in optical performance due to errors in processing and assembly adjustment can be prevented, which is preferable. In this case, there is little deterioration in rendering performance even when the image surface deviates, which is preferable. 
     When the lens surface is an aspherical surface, the aspherical surface may be any one of aspherical surfaces formed by grinding, a glass-molded aspherical surface formed by molding a glass into an aspherical shape, and a composite type aspherical surface formed of a resin on a glass surface in an aspherical shape. Further, the lens surface may be a diffractive surface. The lens may be a gradient index lens (GRIN lens) or a plastic lens. 
     The aperture stop is preferably disposed in the neighborhood of the second lens group or in the second lens group, but a lens frame may serve as the aperture stop instead of the member serving as the aperture stop. 
     Each of the lens surfaces may be provided with an antireflection film having high transmittance in a wide wavelength range to reduce flare and ghost and achieve optical performance with high contrast. 
     EXPLANATION OF NUMERALS AND CHARACTERS 
     
         
         G 1 : first lens group 
         G 2 : second lens group 
         G 3 : third lens group 
         G 4 : fourth lens group 
         G 5 : fifth lens group 
         S: aperture stop 
         GR: rear lens group 
         GE: last lens group 
         GF: F lens group