Zoom lens and image pickup apparatus having the same

A zoom lens comprising:

• a first lens group of positive refracting power;
• a second lens group of negative refracting power;
• a third lens group of positive refracting power;
• and
• a fourth lens group of positive refracting power,
• wherein said first to fourth lens groups are provided in this order from an object side to an image side,
• wherein, during zooming from a wide-angle end to a telephoto end, at least said first lens group moves,
• wherein said third lens group includes, in an order from the object side to the image side, a first lens sub-group of positive refracting power and a second lens sub-group of negative refracting power,
• wherein said second lens sub-group of said third lens group is comprised of a single negative lens,
• wherein said first lens sub-group of said third lens group is moved to keep a perpendicular component relative to an optical axis to correct image blur to be produced when said zoom lens vibrates, and
• wherein, when a focal length of said first lens group is denoted by f1 and a the focal length of the whole system at the wide-angle end is denoted by fw, a conditional expression
• 10.0<f1/fw<20.0
• is satisfied.