US2016216496A1PendingUtilityA1
Variable power optical system, optical apparatus and manufacturing method for variable power optical system

Assignee: NIKON CORPPriority: Jul 29, 2013Filed: Jan 23, 2016Published: Jul 28, 2016
Est. expiryJul 29, 2033(~7 yrs left)· nominal 20-yr term from priority
Inventors:Atsushi Shibayama Kosuke Machida
G02B 15/22G02B 15/173G02B 15/1461G02B 15/1451G02B 13/009
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References
Claims
Abstract

Provided is a variable power optical system (ZL) used for an optical apparatus such as a camera ( 1 ). The variable power optical system (ZL) includes, in order from an object: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having negative refractive power; a fourth lens group having positive refractive power; and a fifth lens group. Upon zooming from a wide-angle end state to a telephoto end state, a distance between each of the lens groups changes, and upon focusing from an object at infinity to an object at a close distance, the third lens group moves in the optical axis direction.
Claims

exact text as granted — not AI-modified
1 . A variable power optical system comprising, in order from an object:
 a first lens group having positive refractive power;   a second lens group having negative refractive power;   a third lens group having negative refractive power;   a fourth lens group having positive refractive power; and   a fifth lens group,   upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group changing, a distance between the second lens group and the third lens group changing, a distance between the third lens group and the fourth lens group changing, and a distance between the fourth lens group and the fifth lens group changing,   upon focusing from an object at infinity to an object at a close distance, the third lens group moving in the optical axis direction, and   the following conditional expression being satisfied:
   1.10&lt; f 1/(− f 2)&lt;2.00
 
   
       where 
       f1: focal length of the first lens group 
       f2: focal length of the second lens group. 
     
     
         2 . The variable power optical system according to  claim 1 , wherein the fifth lens group has positive refractive power. 
     
     
         3 . The variable power optical system according to  claim 1 , wherein upon zooming from the wide-angle end state to the telephoto end state, the first lens group moves toward the object. 
     
     
         4 . The variable power optical system according to  claim 1 , wherein upon zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, and the distance between the third lens group and the fourth lens group decreases. 
     
     
         5 . The variable power optical system according to  claim 1 , wherein the following conditional expression is satisfied:
   0.990&lt;( A×B )/( C×D )&lt;1.013     where       A=f 3×(1−β3 w ) 2 ×(1+β3 w )×β bw   2 −Δ×β3 w   2  
       B=fbw ×(1−β bw )+Δ
       C=f 3×(1−β3 w ) 2 ×(1+β3 w )×β bw   2 −Δ×β3 w  
       D=fbw ×(1−β bw )+Δ/β bw  
     Δ= Y max/50
   
       βw: imaging magnification of the third lens group in the wide-angle end state 
       βbw: composite imaging magnification of the fourth and later lens groups in the wide-angle end state 
       Ymax: maximum image height 
       f3: focal length of the third lens group 
       fbw: composite focal length of the fourth and later lens groups in the wide-angle end state. 
     
     
         6 . The variable power optical system according to  claim 1 , wherein upon zooming from the wide-angle end state to the telephoto end state, the fourth lens group and the fifth lens group move toward the object. 
     
     
         7 . The variable power optical system according to  claim 1 , wherein upon zooming from the wide-angle end state to the telephoto end state, the distance between the second lens group and the third lens group increases, and the distance between the fourth lens group and the fifth lens group decreases. 
     
     
         8 . The variable power optical system according to  claim 1 , wherein
 the following conditional expression is satisfied:
   0.35&lt; f 3/ f 2&lt;0.90 
   
       where 
       f3: focal length of the third lens group. 
     
     
         9 . The variable power optical system according to  claim 1 , wherein
 the following conditional expression is satisfied:
   3.50&lt; f 1/ fw&lt; 5.50 
   
       where 
       fw: focal length of the variable power optical system in the wide-angle end state. 
     
     
         10 . The variable power optical system according to  claim 1 , wherein
 the following conditional expression is satisfied:
   0.72&lt; f 4/ f 5&lt;1.45 
   
       where 
       f4: focal length of the fourth lens group 
       f5: focal length of the fifth lens group. 
     
     
         11 . The variable power optical system according to  claim 1 , wherein
 the following conditional expression is satisfied:
   0.15&lt;( D 45 w−D 45 t )/ fw&lt; 0.40 
   
       where 
       D45w: distance between the fourth lens group and the fifth lens group in the wide-angle end state 
       D45t: distance between the fourth lens group and the fifth lens group in the telephoto end state 
       fw: focal length of the variable power optical system in the wide-angle end state. 
     
     
         12 . The variable power optical system according to  claim 1 , further comprising a sixth lens group having positive refractive power, wherein the fifth lens group has negative refractive power. 
     
     
         13 . An optical apparatus comprising the variable power optical system according to  claim 1 . 
     
     
         14 . A variable power optical system comprising, in order from an object:
 a first lens group having positive refractive power;   a second lens group having negative refractive power;   a third lens group having negative refractive power;   a fourth lens group having positive refractive power;   a fifth lens group having negative refractive power; and   a sixth lens group having positive refractive power,   upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group changing, a distance between the second lens group and the third lens group changing, a distance between the third lens group and the fourth lens group changing, a distance between the fourth lens group and the fifth lens group changing, and a distance between the fifth lens group and the sixth lens group changing,   upon focusing from an object at infinity to an object at a close distance, the third lens group moving in the optical axis direction, and   the following conditional expression being satisfied:
   −0.25&lt; ft/f 12 t&lt; 0.10
 
   
       where 
       ft: focal length of the variable power optical system in the telephoto end state 
       f12t: composite focal length of the first lens group and the second lens group in the telephoto end state. 
     
     
         15 . The variable power optical system according to  claim 14 , wherein upon zooming from the wide-angle end state to the telephoto end state, the first lens group moves toward the object. 
     
     
         16 . The variable power optical system according to  claim 14 , wherein upon zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, and the distance between the third lens group and the fourth lens group decreases. 
     
     
         17 . The variable power optical system according to  claim 14 , wherein upon zooming from the wide-angle end state to the telephoto end state, the fourth lens group and the sixth lens group move toward the object. 
     
     
         18 . The variable power optical system according to  claim 14 , wherein upon zooming from the wide-angle end state to the telephoto end state, the distance between the second lens group and the third lens group increases, the distance between the fourth lens group and the fifth lens group increases, and the distance between the fifth lens group and the sixth lens group decreases. 
     
     
         19 . The variable power optical system according to  claim 14 , wherein
 the following conditional expression is satisfied;
   2.00&lt; f 12 w/f 3&lt;5.00 
   
       where 
       f12w: composite focal length of the first lens group and the second lens group in the wide-angle end state 
       f3: focal length of the third lens group. 
     
     
         20 . The variable power optical system according to  claim 14 , wherein the third lens group is constituted only by one negative lens. 
     
     
         21 . The variable power optical system according to  claim 14 , wherein the surface closest to the object in the third lens group is aspherical. 
     
     
         22 . The variable power optical system according to  claim 14 , wherein
 the following conditional expression is satisfied:
   0.45&lt; f 1/ ft&lt; 0.90 
   
       where 
       f1: focal length of the first lens group. 
     
     
         23 . The variable power optical system according to  claim 14 , wherein
 the following conditional expression is satisfied:
   1.00&lt; f 4/ fw&lt; 1.70 
   
       where 
       fw: focal length of the variable power optical system in the wide-angle end state 
       f4: focal length of the fourth lens group. 
     
     
         24 . The variable power optical system according to  claim 14 , wherein
 the following conditional expression is satisfied:
   1.40&lt;(− f 5)/ fw&lt; 2.30
 
   
       where 
       fw: focal length of the variable power optical system in the wide-angle end state 
       f5: focal length of the fifth lens group. 
     
     
         25 . The variable power optical system according to  claim 14 , wherein
 the following conditional expression is satisfied:
   1.60&lt; f 6/ fw&lt; 2.60 
   
       where 
       fw: focal length of the variable power optical system in the wide-angle end state 
       f6: focal length of the sixth lens group. 
     
     
         26 . The variable power optical system according to  claim 14 , wherein at least a part of the fifth lens group is moved so as to have a component in a direction orthogonal to the optical axis. 
     
     
         27 . The variable power optical system according to  claim 14 , wherein upon zooming from the wide-angle end state to the telephoto end state, the fourth lens group and the sixth lens group move together. 
     
     
         28 . The variable power optical system according to  claim 14 , wherein
 the following conditional expression is satisfied:
   0.80&lt; f 5/ f 3&lt;1.30 
   
       where 
       f3: focal length of the third lens group 
       f5: focal length of the fifth lens group. 
     
     
         29 . The variable power optical system according to  claim 14 , wherein the fifth lens group is constituted by a cemented lens created by cementing a biconcave lens and a positive meniscus lens having a convex surface facing the object in order from the object. 
     
     
         30 . The variable power optical system according to  claim 14 , wherein the surface closest to the object in the fifth lens group is aspherical. 
     
     
         31 . An optical apparatus comprising the variable power optical system according to  claim 14 . 
     
     
         32 . A variable power optical system comprising, in order from an object:
 a first lens group having positive refractive power;   a second lens group having negative refractive power;   a third lens group having negative refractive power;   a fourth lens group having positive refractive power;   a fifth lens group having negative refractive power; and   a sixth lens group having positive refractive power,   upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group changing, a distance between the second lens group and the third lens group changing, a distance between the third lens group and the fourth lens group changing, a distance between the fourth lens group and the fifth lens group changing, and a distance between the fifth lens group and the sixth lens group changing,   upon focusing from an object at infinity to an object at a close distance, the third lens group moving in the optical axis direction,   at least a part of the fifth lens group moving so as to have a component in a direction orthogonal to the optical axis, and   the following conditional expression being satisfied:
   0.80&lt; f 5/ f 3&lt;1.30 
   
       where 
       f3: focal length of the third lens group 
       f5: focal length of the fifth lens group. 
     
     
         33 . An optical apparatus comprising the variable power optical system according to  claim 32 . 
     
     
         34 . A method for manufacturing a variable power optical system including, in order from an object:
 a first lens group having positive refractive power;   a second lens group having negative refractive power;   a third lens group having negative refractive power;   a fourth lens group having positive refractive power; and   a fifth lens group,   the method comprising:   disposing each lens group so that, upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group changes, a distance between the second lens group and the third lens group changes, a distance between the third lens group and the fourth lens group changes, and a distance between the fourth lens group and the fifth lens group changes;   disposing each lens group so that, upon focusing from an object at infinity to an object at a close distance, the third lens group moves in the optical axis direction; and   disposing each lens group so that the following conditional expression is satisfied:
   1.10&lt; f 1/(− f 2)&lt;2.00
 
   
       where 
       f1: focal length of the first lens group 
       f2: focal length of the second lens group. 
     
     
         35 . The method for manufacturing a variable power optical system according to  claim 34 , wherein the fifth lens group has positive refractive power. 
     
     
         36 . The method for manufacturing a variable power optical system according to  claim 34 , wherein the following conditional expression is satisfied:
   0.35&lt; f 3/ f 2&lt;0.90   
       where 
       f3: focal length of the third lens group. 
     
     
         37 . A method for manufacturing a variable power optical system including, in order from an object:
 a first lens group having positive refractive power;   a second lens group having negative refractive power;   a third lens group having negative refractive power;   a fourth lens group having positive refractive power;   a fifth lens group having negative refractive power; and   a sixth lens group having positive refractive power,   the method comprising:   disposing each lens group so that, upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group changes, a distance between the second lens group and the third lens group changes, a distance between the third lens group and the fourth lens group changes, a distance between the fourth lens group and the fifth lens group changes, and a distance between the fifth lens group and the sixth lens group changes;   disposing each lens group so that, upon focusing from an object at infinity to an object at a close distance, the third lens group moves in the optical direction; and   disposing each lens group so that the following conditional expression is satisfied:
   −0.25&lt; ft/f 12 t&lt; 0.10
 
   
       where 
       ft: focal length of the variable power optical system in the telephoto end state 
       f12t: composite focal length of the first lens group and the second lens group in the telephoto end state. 
     
     
         38 . The method for manufacturing a variable power optical system according to  claim 37 , wherein
 the following conditional expression is satisfied;
   2.00&lt; f 12 w/f 3&lt;5.00 
   
       where 
       f12w: composite focal length of the first lens group and the second lens group in the wide-angle end state 
       f3: focal length of the third lens group. 
     
     
         39 . The method for manufacturing a variable power optical system according to  claim 37 , wherein
 the following conditional expression is satisfied:
   0.45&lt; f 1/ ft&lt; 0.90 
   
       where 
       f1: focal length of the first lens group. 
     
     
         40 . The method for manufacturing a variable power optical system according to  claim 37 , wherein
 the following conditional expression is satisfied:
   0.80&lt; f 5/ f 3&lt;1.30 
   
       where 
       f3: focal length of the third lens group 
       f5: focal length of the fifth lens group. 
     
     
         41 . A method for manufacturing a variable power optical system including, in order from an object:
 a first lens group having positive refractive power;   a second lens group having negative refractive power;   a third lens group having negative refractive power;   a fourth lens group having positive refractive power;   a fifth lens group having negative refractive power; and   a sixth lens group having positive refractive power,   the method comprising:   disposing each lens group so that, upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group changes, a distance between the second lens group and the third lens group changes, a distance between the third lens group and the fourth lens group changes, a distance between the fourth lens group and the fifth lens group changes, and a distance between the fifth lens group and the sixth lens group changes;   disposing each lens group so that, upon focusing from an object at infinity to an object at a close distance, the third lens group moves in the optical axis direction;   disposing each lens group so that at least a part of the fifth lens group moves so as to have a component in a direction orthogonal to the optical axis; and   disposing each lens group so that the following conditional expression is satisfied:
   0.80&lt; f 5/ f 3&lt;1.30 
   
       where 
       f3: focal length of the third lens group 
       f5: focal length of the fifth lens group.
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