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<div class="elementToProof"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);">Hi,</span></div>
<div class="elementToProof"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);"><br>
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<div class="elementToProof"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);">I have a stupid question about the MRC files output by our Falcon 3 camera. I just acquired a
set of movies in counting mode where the total dose should be on the order of 25 electrons/ A^2, spread over 22 frames. My pixel size is just under 1 A, so my images should have on the order of 20 - 25 electrons per pixel. At least the average over all the
pixels after summing or motion correction should be close to that...</span></div>
<div class="elementToProof"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);"><br>
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<div class="elementToProof"><span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);">When I examine the MRC files output by EPU, I find the following min/max/mean for an example acquisition:</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);">file with fractions (22 frames): min = 0, max = -1, mean = -2 (obviously bogus values)</span></li><li style="font-size: 12pt; font-family: Calibri, Helvetica, sans-serif; color: rgb(0, 0, 0);">
<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);">fractions after recalculating min/mix/mean: min = -23, max = 549, mean = 108.27</span></li><li style="font-size: 12pt; font-family: Calibri, Helvetica, sans-serif; color: rgb(0, 0, 0);">
<span style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);">summed image (non-motion corrected single frame output by EPU): min = 1239, max = 3809, mean = 2382<br>
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<div class="elementToProof" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);">
My stupid question: How do these numbers relate to what should be the counted number of electrons that hit the specimen?
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I suspect that I am seeing some stupid effect of an "average counts per electron" in these images, but I had previously (and I suppose foolishly) assumed that in counted mode images, one count would mean one electron...<br>
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Thanks for any input you can offer, and Happy New Year.<br>
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-- </div>
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politics is more difficult than physics.</div>
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A. Einstein</div>
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David Gene Morgan<br>
Electron Microscopy Center<br>
047E Simon Hall<br>
IU Bloomington<br>
812 856 1457 (office)<br>
812 856 3221 (3200)<br>
<a href="https://urldefense.com/v3/__http://iubemcenter.indiana.edu__;!!Mih3wA!E-FcoZUZdcr3llQ_tQ7nra_aC45SHHOofl5vsdk4RilKOYWBacUzdW1K8BzGLp3U7LbXIfTjwt3E1eA8hKRTl-Y$">http://iubemcenter.indiana.edu</a></div>
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