See the Tiny Tim User's Guide for a description of the output products. For ACS and WFC3, PSFs are calculated for both undistorted (tiny2 output) and distorted (tiny3) images. Only the tiny3 distorted image is sampled at the detector resolution. This product corresponds to the images supplied by the pipeline as "_flt" files. For the other instruments, the distortion is much less and has not been considered in Tiny Tim.