I have an apoferritin dataset collected on one of our scopes which has substantial beam tilt (estimated at ~1.2mrad total). Correcting for this and trefoil/tetra etc improves resolution a lot - from 2.8 to 1.9 - but looking at the log for global CTF fitting, it seems that there is still rather a large residual after the correction is done (see attached).
I’m not sure exactly what this implies - does this mean there is some component that cannot be modeled? any suggestions appreciated. Also to me it looks like in the even terms there is a clear symmetrical pattern which is not being modeled…