[phenixbb] lower limits on grid spacing/binning

Hey Everyone, I have been told by several crystallographers that the general rule of thumb for grid spacing when generating a map is one third the resolution (eg If your crystal structure has a resolution of 1.2 A, your grid spacing should be 0.4). Is there a mathematical reason why this ratio should be maintained or is this simply a holdover from slower computers with lower memory? More importantly for my application, is there a lower limit on how fine the grid spacing can be? In other words, is there a lower limit at which one is oversampling the data for a particular resolution? Any information and/or references would be greatly appreciated. Sincerely, Terry -- P. Therese Lang Post Doc Alber Lab, UC Berkeley