Patent ID: 7880975

Claim:
A zoom lens comprising: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; and a fourth lens group having either the positive refractive power or the negative refractive power, the first through the fourth lens group being arranged in that order from an object side toward an image side, wherein, in the zoom lens, intervals between the lens groups are changed upon zooming, and wherein, when a focal length of an entire system at a wide angle end is fW, a focal length of the entire system at a telephoto end is fT, a focal length of the first lens group is f 1 , a focal length of the second lens group is f 2 , a distance between a position to which the first lens group moves upon zooming, the position being closest to the object side, and a position of the first lens group at the wide angle end is m 1 , and a difference between a largest distance between the first lens group and the second lens group upon zooming and a distance between the first and second lens groups at the wide angle end is X 1 , a condition represented by: 1.3 <f 1/√{square root over (( fW×fT ))}<2.0, 0.2 <|f 2|/√{square root over (( fW×fT ))}<0.4, and 0.3 <m 1 /X 1<0.75 is satisfied.