I'm working on a particle which have C9 symmetry but only has 100 kDa MW. RELION works well before 3D classification. However, Auto3D_refine always gives a resolution at 4.326A exactly whatever dataset size I changed from 160k to 50k. More strangely, when I run PostProcess, the resolution reported is 4.326A as well, exactly same as before. However, when I viewed 3D models before and after PostProcess, resolution was improved obviously. After post process, I can see side chains clearly, and even pigment molecules in the protein. Resolution of the map is definitely higher than before post process, around 3.5-3.7A roughly as I estimated. I viewed FSC, in high resolution region, it is quite noise. Is this because RELION does not use C9 symmetry for FSC calculation?   

Any advice is greatly appreciated. 

Best regards

Dr. Pu Qian

The University of Sheffield