What can be the reason(s) causing plummet of FSC curve?

3D Refinement
1

Hi, all

All my datasets met the same problem that the resolution numbers look good but the true resolution seem to be much lower.
I found that all of the unmasked FSC curves plummeting to 0.4-0.6 like the following pic. (~540,000 particles)
image
Other refined curves also dropped around same resolution range.
They all look like basin-shaped at the same resolution range.

I am wondering is this feature normal?
Is there anything can lead to this kind of FSC curve?
What can I do to improve it?

Beat,
Jessica

2

Hi Jessica

This is normal - the unmasked FSCs are lower resolution because they include a much larger contribution (background noise) from the solvent region.

Cheers
Oli

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3

It’s normal but it can still get better! (Try Class3D in Relion, referenced based classification in cryoSPARC, local refinement, etc.)

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4

Yes absolutely - particularly with 540k particles remaining, plenty of room for improvements! :slight_smile: Just wouldn’t worry about unmasked FSC being worse than masked, was what I meant

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