Zoom lens

A zoom lens comprising:

• in succession from the object side,
• a first lens unit of positive refractive power;
• a second lens unit of negative refractive power;
• a third lens unit;
• and
• a fourth lens unit of positive refractive power,
• said second and third lens units being moved to effect zooming, said first lens unit comprising, in order from the object side, a front lens subunit fixed during focusing and a rear lens subunit movable toward the object side for focusing from an infinite object to a short distance object, said front lens subunit comprising a cemented lens comprising a first negative lens and a second positive lens cemented together, said rear lens subunit comprising a first positive lens and a second positive lens, said zoom lens satisfying the following conditions:
• f/11/f1<-10
• 0.85<f12/f1<1.1
• -1.77<(R2+R1)/(R2-R1)<-1.15
• 0.45<(R3+R2)/(R3-R2)<0.9
• -0.7<(R3+R1)/(R3-R1)<0.2
• where f1, f11, and f12 are the focal lengths of said first lens unit, said front lens subunit, and said rear lens subunit, respectively, and Ri is the radius of curvature of the ith lens surface as counted from the object side of said first lens unit.