[3dem] K3 CDS mode issue

[Marcus FISLAGE]

Hi Daniel,

the stripes you have shown are familiar to me, if you made the gain reference at a different intensity than the actual images.
I.e. Your gain reference count was 8 e-/px/s and the beam intensity after your sample in thin/normal ice is around 8 e-/px/s you will not see them, but if you are then in thick ice and the intensity may only be 5 e/px/s, the stripes are obviously.
Our Gatan engineer told us that it is a scaling artefact error in Digital micrograph and that newer version would supposedly fix it. Therefore, you may want to check how old your DM version is, especially if you have an older K3.

Cheers
Marcus


______________________________________

Dr. Marcus Fislage

EM Manager

BECM
VIB-Center for Structural Biology
VUB (Vrije Universiteit Brussel)
Building P1T, room 0.01
Pleinlaan 2
1050 BRUSSELS

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From: 3dem <3dem-bounces at ncmir.ucsd.edu> on behalf of Daniel Toso <dtoso at berkeley.edu>
Sent: Friday, December 17, 2021 12:30 AM
To: 3dem at ncmir.ucsd.edu <3dem at ncmir.ucsd.edu>
Subject: [3dem] K3 CDS mode issue

Hello Everyone,

We have been having an issue with one of our older K3 cameras since last year. Namely, in CDS mode we are getting stripes in our images that do not get removed by gain correction and become worse as the dose goes further from 7.5 e-/pixel/sec., which will occur quite often in thicker ice. See attached image for an example.

We tried having Gatan (Ametek) fix the issue but they do not have a solution beyond buying a new sensor.

I was wondering if this is a widespread issue. Also, if there is any solution besides no longer imaging in CDS mode. We have heard that it is also seen at UCSF. Any advice would be appreciated.

Thanks very much!

Best regards,

Dan
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