Image stabilizing zoom lens

A zoom lens comprising, in the following order from an object side:

• a first lens unit that has a positive refractive power as a whole and that is fixed with respect to an image plane;
• a second lens unit that has a negative refractive power as a whole and that causes a variable power action when moved along an optical axis;
• an aperture stop that is fixed with respect to the image plane;
• a third lens unit that has a positive refractive power as a whole and that is fixed with respect to the optical axis direction when zooming and when focusing;
• a fourth lens unit that has a negative refractive power as a whole and that is fixed with respect to the image plane;
• and
• a fifth lens unit that has a positive refractive power as a whole and that is movable along the optical axis such that the image plane, which is displaced by a movement of the second lens unit along the optical axis and by a movement of the object, is maintained at a constant position from a reference plane,
• wherein the entire third lens unit is movable in a direction perpendicular to the optical axis in order to stabilize an image,
• the fifth lens unit is moved to the object side as the object point approaches, and
• the following conditional expressions (1) and (2) are satisfied
• 0.035<|βw·βt/Z|<0.075 (1)
• βw:
• magnification ratio of the second lens unit at the wide-angle end
• βt:
• magnification ratio of the second lens unit at the telephoto end
• Z:
• zoom ratio
• 0<(d45T−d45N)/(IM·Z)<0.04 (2)
• d45T:
• interval between the fourth lens unit and the fifth lens unit in a telephoto position
• d45N:
• interval between the fourth lens unit and the fifth lens unit when the second lens unit is in an equal magnification position
• IM:
• image size
• Z:
• zoom ratio.