Hi Matt, That is normal Chimera behavior. If you open a large volume file it shows just one plane and there is a slider in the volume dialog to flip through planes. This is to allow fast initial display. If you want to display all planes press the "All" button below the Planes slider. The volume size at which only a single plane is shown is controlled by the volume dialog setting under "data display options" called "show plane when data larger than X voxels". I think the default is 256 million voxels (grid points). You can change that and save the default volume dialog settings (menu entry at bottom of Features menu). With a 4 Gvoxel map (2000x2000x1000) Chimera is going to of course subsample the data, i.e. volume step size is going to be greater than 1 if you try to show the full data. Tom