Relion4.0 handedness definition in relion_tomo_import_tomograms

[logicvay2010]

Hey all,

I am kind of confused about the following definition: --hand: the handedness of the tilt geometry. The value of this parameter is either +1 or -1, and it describes whether the focus increases or decreases as a function of Z distance. It has to be determined experimentally. In our experiments, it has always been -1.

My question is, what is the exactly definition of the focus increases? For example, If the focus changed from -3um(at z=0) to -5um(at z=500). Does this means the focus decreased? And I should use -1 for my handedness?

Thanks, Hui