Patent ID: 6449101
Filing Date: 2002-09-10
Classification: G02B

Abstract:
A projection zoom lens comprising:a first optical group comprising a first lens L1, a second lens L2, and a third lens L3, the first optical group having an effective focal length (EFL) of fI; a second optical group comprising a fourth lens L4 and a fifth lens L5, the second optical group having an EFL of fII; a third optical group comprising a sixth lens L6, a seventh lens L7, and an eighth lens L8, the third optical group having an EFL of fIII; a fourth optical group comprising a ninth lens L9, the fourth optical group having an EFL of fIV; and a fifth optical group comprising a tenth lens L10, an eleventh lens L11 that is a biconcave lens, a twelfth lens L12 that is a biconvex lens, and a thirteenth lens L13 that is a biconvex lens, the lenses L10 to L12 forming a triplet, the fifth optical group having an EFL of fV; wherein the first optical group to the fifth optical group are arrayed in order along an optic axis from an object side to an image side, and the optical groups satisfy the following conditions: âˆ’0.45f11/fV)V10+V12âˆ’2V11>44; 2N11âˆ’N10âˆ’N12>0.50; and0.5fN+fP)/(fP)<0.9; where the lenses L1 to L13 have focal lengths f1 to f13 respectively, Abbe numbers V1 to V13 respectively, and index of refractions values N1 to N13 respectively, and wherein fN is the effective focal length (EFL) of the first and the second optical groups, and fP is the EFL of the third, fourth and fifth optical groups.