The vertical acceptance of the Photon Factory storage ring had been limited by a narrow vacuum chamber at an insertion device. To increase the acceptance, the vertical betatron function at the device was reduced. This modification resulted in an increase of the beam lifetime by a factor of 1.5 and enabled one to operate the ring continuously for 24 h without a beam injection. The effects of the optics modification on the beam lifetime, beam injection, betatron tune shifts produced by the insertion devices, and the brilliance of the synchrotron light are presented.