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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi Tommi<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">There is an option in low dose to take a defocus series. Make sure that that is not activated. It is designed to take an exposure at a certain defocus from
where you set it in focus mode. That would me my best guess. Good luck.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Bob<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> 3dem [mailto:3dem-bounces@ncmir.ucsd.edu]
<b>On Behalf Of </b>Tommi White<br>
<b>Sent:</b> Monday, April 27, 2015 5:53 PM<br>
<b>To:</b> 3dem@ncmir.ucsd.edu<br>
<b>Subject:</b> [3dem] Low Dose Focus/Exposure<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Dear 3DEM.<br>
<br>
Perhaps the community can assist with this issue we are struggling with. In Low Dose on our Tecnai F30, the Low Dose focus image has a different defocus value (using FFT) versus Low Dose Exposure.
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I have been checking this on a relatively flat cross-grating (not cryo) specimen. I set LD exposure to be zero defocus (with focus knob), but when I switch over to LD focus (~ 3 micron away on tilt axis) the image is defocused (~ -2 micron).
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I believe there is some 200 kV procedure alignment that must not be set properly - but am not quite sure which one...any suggestions on what to tweak to get this exposure/focus area reflecting the same defocus?<o:p></o:p></p>
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<p class="MsoNormal">Thanks for any suggestions...<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Tommi<o:p></o:p></p>
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<p class="MsoNormal">Tommi A. White, Ph.D.<o:p></o:p></p>
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<p class="MsoNormal">Associate Director, Electron Microscopy Core Facility<o:p></o:p></p>
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<p class="MsoNormal">Assistant Professor of Biochemistry<o:p></o:p></p>
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<p class="MsoNormal">University of Missouri<o:p></o:p></p>
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<p class="MsoNormal">W125 Veterinary Medicine<o:p></o:p></p>
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<p class="MsoNormal">Columbia, MO 65211<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">573-882-8304<br>
<a href="http://emc.missouri.edu">http://emc.missouri.edu</a><o:p></o:p></p>
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