Patent ID: 8654449

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, the first lens unit including a plurality of negative lenses; a second lens unit having a positive refractive power; a third lens unit having a positive refractive power; and a fourth lens unit, wherein the first lens unit do not move for zooming, while the second lens unit, the third lens unit, the fourth 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 D2, D3, and D4 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.