US Patent 7889437 Zoom lens and image pickup apparatus having zoom lens

A zoom lens includes, in order from an object side to an image side, first through fourth lens units. The first lens unit has positive refractive power, and the second lens unit has negative refractive power. The third lens unit has positive refractive power, the third lens unit having at least one positive lens and a plurality of negative lenses that include, in order from the object side to the image side, a first positive lens, a first negative lens, and a second negative lens. The fourth lens unit has positive refractive power. The zoom lens performs zooming by changing the distance between the lens units. The first positive lens is a positive lens closest to the object side among the at least one positive lens. The first negative lens is a negative lens closest to the object side among the plurality of negative lenses.