Dear CCP4bb members, I have two questions about imosflm integration and scaling process (my data is 3A resolution and 0.5 degree mosaicity):
1. I have warnings after integration saying the twist variance is too large (from -0.26 to 0.33, which is larger than 0.5), suggesting that cell parameters may be wrong, and reindex to the right space group may be needed. After I read the imosflm tutorials from internet, the tutorials says "For weak images the tilt and twist may not be well defined, and might refine to large values (greater than one degree). In such cases these parameters should be fixed. It is not generally recommended to fix any other detector parameters." Does this mean if I see twist variance greater than "1" then I need to fix both "tilt' and "twist" value before integration in imosflm? In my case the variance is greater than 0.5 but less than 1, do I still need to fix both "tilt" and "twist" value? 2. I am not sure if iMosflm can be set to output the scale of specific space group. For example, in my data set even though the integration is done at P321 space group, after click "quick symm" or "quick scale" it seems the program automatically choose what it thinks the most likely space group P6222, not P321, I know in HKL2000 there is an option to choose specific group and scale it, how to do this in iMosflm? I'd like to scale the data to P321 and some subgroups in P3 but not P6222. Thanks for any inputs.
