[3dem] K3 optimal dose rate & F20 parallel illumination

[Israel Fernandez]

hi again,

We operate the Polara and the F20 in microprobe, with small C2 apertures
[50um for the F20, and 30um for the Polara, if i remember well...] and we
have the feeling is pretty close to parallel. Win Hagen reported in twitter
a under 2A reconstruction of apo-fe in microprobe AND FalconII in linear
mode...so...

On Thu, Feb 14, 2019, 18:56 Craig Yoshioka <yoshiokc at ohsu.edu> wrote:

> Oh, I have one comment about nP vs uP.  Yes, you can get a smaller
> parallel beam in nP -but- it is also way more sensitive to changes in beam
> size in nP.  As a result, we have been able to get below 3Å on an Arctica
> in microprobe, even when the beam size was not set to be perfectly
> parallel- it remains fairly close over a pretty large range.  This is a way
> more convenient configuration for a lot of use.
>
>
>
>
>
>
> On Feb 14, 2019, at 11:57 AM, Craig Yoshioka <yoshiokc at ohsu.edu> wrote:
>
> Hi Gary,
>
> We haven’t exhaustively tested yet, but we have been targeting around
> 15-20eps on the K3 and have been getting nice results.  This general range
> was based on the 400 -> 1500 read rate increase.
>
> At very high-magnifications 15eps is quite a high flux, so sometimes we
> will go below 10eps just so that we don’t have to push very high FPS (40+)
> with < 1 sec exposures.  We have seen some mild pattern noise occasionally
> creep into images when trying to save at high frame rates.  Not sure yet if
> this is just our K3, or if it also seen by others.  So far it doesn’t seem
> to be a problem in practice, but feedback from others if they have seen
> this would be appreciated.
>
> Cheers,
> -Craig
>
>
> On Feb 14, 2019, at 11:45 AM, Garry P Morgan <Garry.Morgan at Colorado.EDU>
> wrote:
>
> thanks everyone.
>
> On Feb 14, 2019, at 11:53 AM, Reyes, Francis <
> francis.reyes at thermofisher.com> wrote:
>
> Yes it is advisable to work in nanoprobe. At parallel illumination and a
> 50 um C2 you should have around a 1.8um illuminated area.
>
>
> Francis Reyes, Ph.D
> Engineer III, Field Applications
> Materials & Structural Analysis
>
> Thermo Fisher Scientific
> 5350 NE Dawson Creek Drive
> Hillsboro, OR 97124
> Phone - +1 (720) 322-6150 <+1%20(720)%20322-6150>
> francis.reyes at thermofisher.com
> thermofisher.com
>
> On Feb 14, 2019, at 12:36 PM, Garry P Morgan <Garry.Morgan at colorado.edu>
> wrote:
>
> CAUTION: This email originated from outside of the organization. Do not
> click links or open attachments unless you recognize the sender and know
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>
>
> Hello all,
>
> i’m looking for some info on the optimal dose rate for acquiring K3 movie
> stacks.  i would appreciate it if any of you could send me your optimum
> acquisition parameters for imaging cry-samples for SPA…ie, dose rate, best
> frame rate/number of frames, etc.
>
> i’m also trying to figure out how to setup my low dose so that we have
> parallel illumination for our record images (on an FEI Tecnai F20). the
> problem i see is that in microprobe the beam is spread much too wide to
> image/expose a single hole at a time at our record mag. is it advisable to
> work in nano probe to get a smaller beam that is parallel? any advice on
> this would be appreciated.
>
> thanks,
> Garry
>
>
>
> ________________________________
> Garry Morgan
> Director  —  Boulder EM Services —  Department of MCD Biology
> Campus Box 347  —  University of Colorado  —  Boulder, CO 80309
> phone:  303-492-8402
>
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