[3dem] [External] RE: astigmatism in low mag mode?

[Morgan, David Gene]

Cindy,

Thanks.  I know how to fix it, but since I have fixed it several times in the past 6-8 weeks, and it keeps happening, I am trying to determine _why_ it is happening.  As a facility manager, I suspect one of my users is doing something to cause this, but it's hard to imagine what that might be since the images look so bad when you really examine them...

--
    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)
      https://urldefense.com/v3/__http://iubemcenter.indiana.edu__;!!Mih3wA!FuTDBZp4qLrtjErWoQycPmuYJdTOwBk-0x5U3zuXRdlbSignwk5iYEcsucCvvhFUYv1Yz62mD4ojfpQHNbaccRQ$ 
________________________________
From: Schwartz, Cindi (NIH/NIAID) [E] <cindi.schwartz at nih.gov>
Sent: Friday, April 19, 2024 10:35 AM
To: Morgan, David Gene <dagmorga at indiana.edu>; 3dem at ncmir.ucsd.edu <3dem at ncmir.ucsd.edu>
Subject: [External] RE: astigmatism in low mag mode?


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Hey David!



That happened to us. Put in a 200 mesh grid (either holey carbon or cross-grating), highest LM mode, then make it eucentric and in focus. Use a continuous imaging mode and live FFT (in SerialEM) and turn on diffraction stigmators. Then stigmate away. I don’t know how we lost our either. But it’s relatively easy to get it back once you know how.



Cheers,



Cindi L. Schwartz

(she/her/why?<https://urldefense.com/v3/__https://www.edi.nih.gov/blog/communities/what-are-gender-pronouns-why-do-they-matter__;!!Mih3wA!FuTDBZp4qLrtjErWoQycPmuYJdTOwBk-0x5U3zuXRdlbSignwk5iYEcsucCvvhFUYv1Yz62mD4ojfpQHHYdeT8E$ >)

Electron Microscopist

Rocky Mountain Labs/NIAID/NIH

903 South 4th Street

Hamilton, MT  59840

406-363-9228

Cindi.Schwartz at NIH.gov<mailto:Cindi.Schwartz at NIH.gov>



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From: 3dem <3dem-bounces at ncmir.ucsd.edu> On Behalf Of Morgan, David Gene
Sent: Thursday, April 18, 2024 5:30 PM
To: 3dem at ncmir.ucsd.edu
Subject: [EXTERNAL] [3dem] astigmatism in low mag mode?



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)
      https://urldefense.com/v3/__http://iubemcenter.indiana.edu__;!!Mih3wA!FuTDBZp4qLrtjErWoQycPmuYJdTOwBk-0x5U3zuXRdlbSignwk5iYEcsucCvvhFUYv1Yz62mD4ojfpQHNbaccRQ$ <https://urldefense.com/v3/__http://iubemcenter.indiana.edu__;!!Mih3wA!DoYeq0j6H_L51aPzU4dHuYcoyIRvBYbYNL5C3O_mZFq2lcAoGsdmlLe5_g1aarhF2Azk-Tidh2slunStQLpsF9U$>

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