[3dem] magnification question

[Wim Hagen]

Hi,

In the old days with film cameras, when the screen went up, the indicated magnification changed to reflect the magnification at the film camera plane. Any digital camera mounted below that plane would thus get a post-magnification, typically 1.4x for Philips/FEI/TFS instruments. Without film cameras (Glacios, Arctica, Krios) this behaviours has at some point been removed from the software. As stated by others, magnification is the worst thing to use as a parameter, we should just stick to calibrated physical pixel size of the detector. 

Wim Hagen
EMBL Heidelberg

> On 24. Jun 2020, at 15:58, Morgan, David Gene <dagmorga at indiana.edu> wrote:
> 
> Hi,
> 
>     Several people have reported what Zongli said about the mag changing when the screen is inserted.  This does _not_ happen with our Artica and I think that it does not happen with most/all Glacios/Artica/Krios TEM's.  Either ThermoFisher has deliberately turned off this behavior, or it is another bug in recent release of the software.
> 
> -- 
>     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!TzwMv-MtKkWs08XTyYwqbbyZpUvaqYJ5DNlXONXt6nyhBlBJOPIylv_2GPuPWZgdCQ$  <https://urldefense.com/v3/__http://iubemcenter.indiana.edu__;!!Mih3wA!SjlQ155eJJt7G-lOVflOWQRvfeqzYhZqcJOIHQMJ1pyb1REIo0KAIgpLgeJ2RxUStg$>
> From: Michael Elbaum <michael.elbaum at weizmann.ac.il <mailto:michael.elbaum at weizmann.ac.il>>
> Sent: Wednesday, June 24, 2020 3:20 AM
> To: Zongli Li; Morgan, David Gene
> Cc: 3dem at ncmir.ucsd.edu <mailto:3dem at ncmir.ucsd.edu>
> Subject: [External] Re: [3dem] magnification question
>  
> This message was sent from a non-IU address. Please exercise caution when clicking links or opening attachments from external sources.
> 
> Just a heads-up then... I was shocked to see that the magnification written into a file name by the Talos software depends on the size of the monitor attached. Maybe this is STEM-specific? It's very misleading. Altogether magnification is a slippery concept though. The pixel sampling is much less ambiguous: what length in the specimen does a pixel in the recorded file represent? Multiply by the number of pixels for the field of view. It's the same image whether you view on your phone or projected onto the wall.
> 
> Michael
> From: 3dem <3dem-bounces at ncmir.ucsd.edu> on behalf of Zongli Li <zongli.li at gmail.com>
> Sent: Tuesday, June 23, 2020 11:38:26 PM
> To: Morgan, David Gene
> Cc: 3dem at ncmir.ucsd.edu
> Subject: Re: [3dem] magnification question
>  
> Hi David Gene,
> 
> The magnifications reported by a Talos Arctica user interface should be " mag on the viewing screen" if the viewing screen is inserted, and will change to " mag on the CCD" when viewing screen is extracted. But as Sacha pointed out, what matters is really the calibrated mag on the whatever camera you have used for calibration and data collection, and this mag will not show up in the user interface, but stored in the magnification table in Gatan GMS if you are using Gatan CCD/K2/K3 camera.
> 
> Best,
> 
> Zongli
> 
> On Tue, Jun 23, 2020 at 1:50 PM Morgan, David Gene <dagmorga at indiana.edu <mailto:dagmorga at indiana.edu>> wrote:
> Hi,
> 
>     Does anyone happen to know whether the magnifications reported by a Talos Artica are supposed to be "mag on the viewing screen" or "mag at the film plane"?  We clearly have a serious issue with the calibrated magnifications on our microscope, but I just recalibrated it and got more or less the same lousy magnifications.  I'm trying to understand our issues, and knowing what the microscope thinks it is reporting would be helpful.  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!TzwMv-MtKkWs08XTyYwqbbyZpUvaqYJ5DNlXONXt6nyhBlBJOPIylv_2GPuPWZgdCQ$  <https://urldefense.com/v3/__http://iubemcenter.indiana.edu__;!!Mih3wA!Q1NuuXpLaELUTGJgvoiPm1e0cHpDssbesoFay-9J7tLFPfHrCncsLjz01d4djDLt9Q$>_______________________________________________
> 3dem mailing list
> 3dem at ncmir.ucsd.edu <mailto:3dem at ncmir.ucsd.edu>
> https://mail.ncmir.ucsd.edu/mailman/listinfo/3dem <https://mail.ncmir.ucsd.edu/mailman/listinfo/3dem>
> _______________________________________________
> 3dem mailing list
> 3dem at ncmir.ucsd.edu
> https://mail.ncmir.ucsd.edu/mailman/listinfo/3dem

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.ncmir.ucsd.edu/pipermail/3dem/attachments/20200624/be71e8f4/attachment-0001.html>