Patent ID: 9019619
Filing Date: 2015-04-28
Classification: G02B

Abstract:
1. A zoom lens comprising: a front group having a plurality of lens units; an aperture stop; and a rear group having a plurality of lens units in this order from a magnification conjugate side to a reduction conjugate side, wherein the front group includes a lens unit having a negative refractive power and configured not to move for zooming, and a front variable power lens unit including one or more lens units moving during zooming in the order from the magnification conjugate side to the reduction conjugate side, the rear group includes a rear variable power lens unit having one or more lens units moving during zooming and a lens unit having a positive refractive power and configured not to move for zooming in this order from the magnification conjugate side to the reduction conjugate side, the aperture stop moves along a locus different from all other lens units of the zoom lens during zooming, the front group includes an auxiliary stop having a constant aperture diameter moving during zooming, and a conditional expression, is satisfied, where Xw and Xt are the length from a focal point position of the front group to the aperture stop at the wide angle end and the telephoto end and βwb and βtb are the imaging magnifications of the rear group at the wide angle end and the telephoto end, respectively.