Zoom lens and image pickup apparatus including the same

A zoom lens comprising, in order from the object side to the image side:

• a first lens unit having positive refractive power;
• a second lens unit having negative refractive power;
• a third lens unit having positive refractive power;
• and
• a fourth lens unit having positive refractive power;
• wherein the third lens unit includes, in order from the object side to the image side
• a 3a'th lens sub-unit having negative refractive power, and
• a 3b'th lens sub-unit having positive refractive power;
• and wherein the second lens unit and the fourth lens unit move on the optical axis during zooming;
• and wherein the 3b'th lens sub-unit moves in a direction perpendicular to the optical axis, thereby displacing an image in the direction perpendicular to the optical axis;
• and wherein the 3a'th lens sub-unit includes
• a negative lens element G3an both of whose major surfaces are spherical surfaces, and
• a positive lens element, both of whose both major surfaces are spherical surfaces;
• and wherein the 3a'th lens sub-unit includes
• a positive lens element G3bp having an aspherical lens surface, and
• a negative lens element;
• and wherein, when assuming that the indices of the materials of the negative lens element G3an and the positive lens element G3bp are NG3an and NG3bp respectively, a condition of
• 0.25≦NG3an−NG3bp
• is satisfied;
• and wherein the first lens unit includes, in order from the object side to the image side
• a negative lens element G11,
• a positive lens element G12,
• a positive lens element G13, and
• a positive lens element G14;
• and wherein when assuming that the Abbe numbers of the materials of the positive lens element G12, positive lens element G13, and positive lens element G 14 are vdG12, vdG13, and vdG14, the conditions
• 60.1<vdG12<75.1
• 60.1<vdG13<75.1
• 49.1<vdG14<60.1
• are satisfied.