Patent ID: 8922699

Claim:
A zoom lens, comprising: a first lens group having a positive refracting power and fixed in a direction of an optical axis; a second lens group having a negative refracting power and movable in the direction of the optical axis to carry out a zooming action; a third lens group having a positive refracting power and fixed in the direction of the optical axis; a fourth lens group having a negative refracting power and movable in the direction of the optical axis to correct a variation of an image forming position and correct a change of the image forming position caused by a change of an object distance; and a fifth lens group fixed in the direction of the optical axis; the first, second, third, fourth and fifth lenses being disposed in order from the object side to the image side; the zoom lens satisfying the following expression (1) and (2) 0.5 <f 1/( fw·ft ) 1/2 <1.8 (1) −0.4 <f 3 /f 5<0.4 (2) where f 1 is a focal length of the first lens group; fw a focal length of the entire lens system in a wide angle end state; ft a focal length of the entire lens system in a telephoto end state; f 3 a focal length of the third lens group; and f 5 a focal length of the fifth lens group.