Patent ID: 9069157
Filing Date: 2015-06-30
Classification: G02B

Abstract:
1. A projection zoom lens comprising: a first lens group disposed on a most magnification side and having a positive power, the lens group being fixed at a time of zooming; a final lens group disposed on a most reduction side and having a negative power, the lens group being fixed at the time of zooming; and a plurality of lens groups disposed between the first and final lens groups and moved at the time of zooming along an optical axis in association with each other for the zooming and correction of image plane shift arising from the zooming, wherein: the final lens group comprises a lens having a positive power on the most reduction side; the plurality of lens groups moved at the time of zooming comprises a second lens group having a negative power, a third lens group having a positive power, and a fourth lens group having a positive power arranged in this order from the magnification side; the second and third lens groups are moved from the magnification side to the reduction side when zooming is performed from the wide angle end to the telephoto end, and the fourth lens group is moved once to the magnification side and then to the reduction side when zooming is performed from the wide angle end to the telephoto end; and a distance on an optical axis between the third lens group and the fourth lens group at the wide angle end is larger than a distance on an optical axis between the second lens group and the third lens group at the wide angle end.