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Zoom lens and image pickup apparatus










Image Number 2 for United States Patent #8098301.

Provided is a zoom lens including a first lens group, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power, wherein conditional expressions f12/fw>2.0, f2/fw<-2.0, -2.0.ltoreq.f12/f2.ltoreq.-0.5, and .nu.d21-.nu.d22>20 are satisfied, where f12 is a focal length of a single lens having a positive refractive power in the first lens group, f2 is a focal length of the second lens group, fw is a focal length of the total lens system at a wide angle end, .nu.d21 is an Abbe number of the lens having a negative refractive power in the second lens group for the d-line, and .nu.d22 is an Abbe number of the lens having a positive refractive power in the second lens group for the d-line.








 
 
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