Patent ID: 8400720

Claim:
A zoom lens, comprising in order from a magnification conjugate side to a reduction conjugate 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 positive refractive power; a fourth lens unit having a negative refractive power; a fifth lens unit having a negative refractive power; and a sixth lens unit having a positive refractive power, wherein the first lens unit and the sixth lens unit do not move for zooming, while the second lens unit, the third lens unit, the fourth lens unit and the fifth lens unit move to the magnification conjugate side during zooming from a wide-angle end to a telephoto end, wherein each of the second lens unit and the third lens unit is composed of a single positive lens, and wherein the following conditional expressions are satisfied: 0.8 <D 3/ D 4<1.2; 1.2 <D 3/ D 2<2.0; and 0.2 <D 4 /L< 0.4, where D 2 , D 3 and D 4 represent movement amounts of the second lens unit, the third lens unit and the fourth lens unit during zooming from the wide-angle end to the telephoto end, respectively, and L represents a lens length.