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Hi, Can anyone suggest some starting parameters for using sx3dvariability in Sphire/Sparx? I have about 68,000 particles, 1.16Å pixel size, 256x256 boxsize, and a resolution of 4.3Å. Should I bin the images, how many img_per_grp (default is 10 but example uses 100)... Thanks. Also, how long will this take if I only have 40 cores for the job? Best wishes, Reza Reza Khayat, PhD Assistant Professor City College of New York Department of Chemistry New York, NY 10031 ________________________________ From: Collaborative Computational Project in Electron cryo-Microscopy <[log in to unmask]> on behalf of Shawn Zheng <[log in to unmask]> Sent: Thursday, April 13, 2017 3:23 PM To: [log in to unmask] Subject: Re: [ccpem] Motion Correction of Low Dose Datasets Hi Joshua, The rule of thumb is to use a group number as small as possible to get reliable motion correction. When you see many times of message of repeating measurements on larger patch, this is a sign of unreliable motion correction. Someone else also suggested to use larger b factor. The default is 100. You can double it. Best Shawn On Thu, Apr 13, 2017 at 10:00 AM Joshua Lobo <[log in to unmask]<mailto:[log in to unmask]>> wrote: Hi CCPEM When performing motion-correction of low-dose data sets what would be the best method to optimize the group parameter ( to group frames in order to increase signal).Is there a rule of thumb based on dose accumulated or a particular metric used to track the effect of grouping on the actual signal . Any inputs or suggestions on how this is usually done would be really helpful Sincerely Joshua Lobo