Zoom lens and image pickup apparatus using the same

A zoom lens comprising in order from an object side:

• a first lens unit having a negative refractive power;
• a second lens unit having a positive refractive power;
• a third lens unit having a negative refractive power;
• and
• a fourth lens unit having a positive refractive power, wherein
• at a time of zooming, distances between lens units vary, and
• a distance between the first lens unit and the second lens unit becomes smaller at a telephoto end than at a wide angle end, and a distance between the second lens unit and the third lens unit becomes longer at the telephoto end than at the wide angle end, and
• the third lens unit includes one negative lens, and
• the negative lens is a focusing lens, and
• the focusing lens moves toward the object side at a time of focusing to an object at a close distance, and
• the following conditional expressions (1), (2), (3), and (22) are satisfied:
• 0.4<|f1|/|f2|<1.2 (1)
• 0.3<L2/L1<0.95 (2)
• 0.6<Lt/Lw<1 (3)
• 0.1<(r3ff+r3fb)/(r3ff−r3fb)<10 (22)
• where,
• f1 denotes a focal length of the first lens unit,
• f2 denotes a focal length of the second lens unit,
• L1 denotes a thickness on an optical axis of the first lens unit,
• L2 denotes a thickness on an optical axis of the second lens unit,
• Lw denotes an overall length of the zoom lens at the wide angle end,
• Lt denotes an overall length of the zoom lens at the telephoto end,
• r3ff denotes a radius of curvature of an object-side surface of the focusing lens, and
• r3fb denotes a radius of curvature of an image-side surface of the focusing lens, and here
• the overall length is a distance from a lens surface nearest to object up to a paraxial image plane, and is a distance in a case in which no air conversion is carried out.