Patent ID: 9664884
Date: 2017-05-30
CPC Classifications: G02B

Claim:
1. A projection zoom lens consisting of, in order from the magnification side to the reduction side: a first lens group having a negative refractive power; a second lens group having a positive refractive power; a third lens group; a fourth lens group having a positive refractive power; a fifth lens group; and a sixth lens group having a positive refractive power; the distances among all adjacent lens groups changing when changing magnification; the distance between the first lens group and the second lens group being shorter at the telephoto end than at the wide angle end; the distance between the second lens group and the third lens group being longer at the telephoto end than at the wide angle end; the distance between the third lens group and the fourth lens group being shorter at the telephoto end than at the wide angle end; the distance between the fourth lens group and the fifth lens group being longer at the telephoto end than at the wide angle end; the distance between the fifth lens group and the sixth lens group being longer at the telephoto end than at the wide angle end; a lens having a concave surface toward the magnification side in the paraxial region and a negative refractive power in the paraxial region being provided most toward the magnification side in the first lens group; and the fifth lens group having at least one negative lens, wherein: the first lens group consists of, in order from the magnification side to the reduction side, a negative lens having a concave surface toward the magnification side, a lens having a convex surface toward the magnification side, a negative lens having a concave surface toward the reduction side, a biconcave lens, and a cemented lens formed by cementing a positive lens and a negative lens together.