[3dem] fc4i defect

[tnakane.protein at osaka-u.ac.jp]

Hi,

> Our institute recently installed a brand new Titan krios with Facon4i.
> But, we are having an issue in the detector as there are two consecutive lines of defect in the detector.
> When we acquire and motioncorr micrographs, we have a thick black line as attached.
> This line sometimes disappears when we use specific programs such as CryoSparc but not working Relion.
> The TF manufacturer claims that the detector is within their spec.
> I would like to request any advice regarding this issue.

Please make sure pixels on these defective lines have 0s in the gain reference.
RELION tries to conceal defects by randomly picking values from a good pixel nearby.

That being said, information on defective pixels is lost and cannot be recovered.
Defect correction only conceals, not fixes, the problem.
In my experience, one can throw away all particles on a defective line and the resolution does not change much.

Best regards,

Takanori Nakane