Patent ID: 7525737

Claim:
A zoom lens comprising, from an object side to an image side: a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; a third lens unit having a positive refractive power; and a fourth lens unit having a positive refractive power, wherein the position of the first lens unit at the telephoto end is closer to the object side than the position of the first lens unit at the wide angle end, the lens units move in such a way that the distance between the first lens unit and the second lens unit at the telephoto end is larger than the distance between the first lens unit and the second lens unit at the wide angle end, the distance between the second lens unit and the third lens unit at the telephoto end is smaller than the distance between the second lens unit and the third lens unit at the wide angle end, and the distance between the third lens unit and the fourth lens unit at the telephoto end is larger than the distance between the third lens unit and the fourth lens unit at the wide angle end, the first lens unit includes two or less lenses including a positive lens, and the second lens unit includes, from the object side to the image side, a negative lens, a compound lens including two optical members having refractive powers of opposite signs, and a positive lens.