| 摘要 |
PROBLEM TO BE SOLVED: To suppress enlargement in size of a device in a projection zoom lens, and attain a wide-angle, a long back focus and an excellent correction of various aberrations.SOLUTION: A projection zoom lens includes: a first lens group G1 that is arranged on a most enlargement side, remains stationary upon zooming, and has a negative refractive power; and more than two movement lens groups that move as causing an interval among the movement lens groups to be mutually changed upon zooming. One of the movement lens groups is arranged adjacent to a first lens group G1. Let a refractive index for the d-line of an i-th negative lens in the first lens group be Ndn(i), a focal length of the i-th negative lens in the first lens group be fn(i), and a maximum effective image circle diameter on a contraction side be Im&phgr;, the projection zoom lens satisfies a conditional expression (1). |
