Hello, I have a very simple question about phenix.fobs_minus_fobs_map, and it's implementation in the GUI. I just want to make sure I am not skipping an important step in generating my isomorphous difference map. I'm trying to create an Fo-Fo map for two data sets at pretty different resolutions, using phases from a model. I truncated the higher-res data so the high resolution limit matches the lower-res data set. Are these 2 mtz files sufficient for input into phenix.fobs_minus_fobs_map, or do I need to use another utility to scale the two data sets together prior to calculating the map coefficients? I suppose another way to ask my question would be, does phenix.fobs_minus_fobs_map perform scaling of the two Fobs arrays before calculating the new map? Thanks for clarifying, Mike -- Michael C. Thompson Graduate Student Biochemistry & Molecular Biology Division Department of Chemistry & Biochemistry University of California, Los Angeles [email protected]