[3dem] astigmatism in low mag mode?

[Morgan, David Gene]

Hi,

Has anyone else encountered terrible astigmatism in low mag mode on a TFS microscope?  We have run into this multiple times in the last several months on our Talos Arctica, and I am trying to understand what is causing it and how we can prevent it.

While looking at this problem, I also realized that I have no idea what lenses are changed when the focus in low mag mode is changed.  I grabbed several screen shots of the "system tab" in the TFS UI, looking for changes in the lenses and deflectors reported there.  Nothing seems to change, even though the images clearly change and the microscope reports defocus changes that seem to make sense...

Any thoughts would be appreciated.  Thanks in advance.

--
    politics is more difficult than physics.
                                             A. Einstein

            David Gene Morgan
        Electron Microscopy Center
             047E Simon Hall
             IU Bloomington
          812 856 1457 (office)
          812 856 3221 (3200)
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