The thick full curve represents the standard radial average of the ratio of the continuum intensity power spectra at disk center in 2013 and 2007 data, the thick dashed curve the modified radial average. The thin curves indicate the modified radial average of MTF ratio for various defocus. The dashed line plots the relative phase default of 1.4π, the full line the relative phase default of 1.2π, and the dotted line the relative phase default of π.